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THE 


ANATOMY 


OF    THE 


HUmAM    BODY. 


BY   J.   CRUVEILHIER, 

n07X8S0B   OF  ANATOMY    TO   THE    FACULTY   OF    MEDICINE   OF   PARIS,    PHYSICIAN    TO    THE   HOSPITAL   Of 
8ALPETBIEBE,   AND  PRESIDENT   OF  THE   ANATOMICAL   SOCIETY  OF  PARIS. 


THE  FIRST  AMERICAN,   FROM  THP  USJ"  .^ARIS  EDITION. 


Edited  by 


GRANVILLE    SHARP    PATTISON,    M.D., 

VK07ESSOR   OF   ANATOMY    IN    THE    UNIVEItSITY    OF    NEW-YORK,    MEMBER    OF   THE    MEDIC0-CHIRUR0IC4I 

SOCIETY   OF    LONDON,   OF   THE   WARNF.RIAN    SOCIETY   OF    NATURAL    HISTORY    OF    EDINBURGH,   OF 

THE   SOCIETE    MEDICALS    D'EMULATION,    AND   SOCIETE    PHILOMATIQUE    OF    PARIS. 


THIRD      EDITION. 

NEW-YORK: 

HARPER  &  BROTHERS,  PUBLISHERS 

329   &    331    PEARL    STREET, 
FRANKLIN   SQUARE. 


1853. 
1\ 


Entered,  according  to  Act  of  Congress,  in  the  year  1844,  by 

Harper  &  Brothers, 
In  the  Clerk's  Office  of  the  Southern  District  of  New-TC  ork 


»  . 


EDITOR'S  PREFACE. 


Numerous  and  excellent  as  the  works  on  Anatomy  are  which  have 
lately  been  reprinted  in  this  country,  still  they  are,  all  of  them,  so  de- 
cidedly inferior  to  the  "  Svstem  op  Anatomy  by  Cruveilhier,"  that 
the  editor  feels  it  unnecessary  to  offer  any  apology  for  having  under- 
taken its  republication.  Occupying,  however,  as  he  does  the  Chair  of 
Anatomy  in  the  Metropolitan  University  of  the  United  States,  the  pro- 
fession may  perhaps  think  that  it  would  have  been  more  becoming  of 
him  to  have  published  a  System  of  Anatomy  of  his  own,  rather  than  to 
have  undertaken  the  humble  office  of  editing  the  work  of  a  European 
anatomist. 

The  reasons  which  have  influenced  him  in  the  course  he  has  pur- 
sued are  the  following : 

The  science  of  Anatomy,  viewed  abstractly,  and  without  reference 
to  its  connexion  with  Physiology,  Pathology,  and  the  Practice  of  Med- 
icine and  Surgery,  is  to  the  student  just  commencing  a  very  dry  and 
uninteresting  study.  Yet  in  this  way  it  is  generally  taught  in  the 
schools,  each  system  being  demonstrated  separately,  without  refer- 
ence to  the  others,  or  to  the  Physiological  and  Pathological  facts  which 
its  demonstrations  tend  to  illustrate.  The  course  followed  by  the 
editor,  as  a  teacher  of  Anatomy,  as  his  numerous  students  are  aware,  is 
very  difierent.  His  great  object  has  always  been  to  endeavour  to  give 
interest  to  every  lesson,  by  making  it  not  a  mere  lecture  on  Anatomy, 
but  a  discourse  illustrating  Physiological  and  Pathological  science,  and 
elucidating  the  principles  which  should  guide  the  practitioner  in  the 
practice  of  his  profession. 

For  the  editor  to  have  prepared  a  mere  system  of  Anatomy  would 
have  been,  in  fact,  merely  to  have  undertaken  the  work  of  a  compiler ; 
originality  was  out  of  the  question,  and  no  industry  nor  effort  could 
have  enabled  him  to  have  produced,  on  this  plan,  a  better  work  tha^ 
the  systems  of  Wilson,  Quain,  or  the  numerous  other  systematic  trea- 
tises on  Anatomy  which  have  already  been  published.  The  editor 
having  been  a  teacher  of  Anatomy  for  more  than  thirty  years,  from 
his  experience  is  fully  aware  of  the  vast  importance  to  the  successful 
performance  of  his  duties  as  an  anatomical  professor,  of  his  being  en- 
abled to  interest  his  pupils  and  to  fix  and  enchain  their  attention,  that  he 
is  very  unwilling  to  do  anything  which  could  have  the  effect  of  taking 
from  the  intoi'(>Ht  or  diminishing  the  freshness  of  his  lectures.     To  pub- 


13430 


IV  EDITOR  8    PREFACE. 

lish  a  system  of  Anatomy  on  the  same  plan  as  that  adopted  in  his  lec- 
tures, he  would,  of  necessity,  require  to  imbody  in  it  the  same  Phys- 
iological, Pathological,  and  practical  views  with  which  they  are  illus- 
trated ;  and  to  have  done  so>  he  cannot  doubt  but  that  the  interest  of 
his  lectures  would  have  been  diminished,  and  that  he  would  in  future 
have  found  it  much  more  difficult  to  fix  the  attention  of  his  pupils. 
This  consideration  has  decided  him  never  to  publish,  so  long  as  he  is 
engaged  in  the  duties  of  teaching,  an  original  work  on  Anatomy. 

The  system  of  Anatomy  of  Cruveilhier  has  recommended  itself  to 
the  editor  for  publication  :  First,  on  account  of  its  decided  superiority 
to  any  other  work  on  Anatomy  which  has  ever  been  published  ;  and, 
secondly,  from  its  being  prepared,  in  some  measure,  in  accordance 
with  the  plan  which  he  follows  in  his  lectures,  many  of  its  details  be- 
ing illustrated  by  Physiological  and  Pathological  references. 

In  republishing  the  work,  the  editor  has  so  restricted  himself  in  the 
performance  of  liis  task  that  he  feels  it  can  neither  add  to  nor  take 
from  his  reputation.  He  has  merely  furnished  to  the  members  of  the 
profession  in  the  United  States  The  System  of  Anatomy  op  Cru- 
veilhier. Several  reasons  have  influenced  him  in  being  sparing  in 
the  introduction  of  notes  or  additional  matter.  First.  The  work  is  in 
itself  so  perfect  as  not  to  require  them.  Secondly.  It  is  very  volumi- 
nous, and  to  have  increased  its  size  would  have  been  to  have  diminish- 
ed its  value.  Thirdly.  The  editor  has  ever  thought  that  an  inde- 
pendent mind  will  shrink  from  mixing  up  and  incorporating  his 
thoughts  with  those  of  another.  If  a  man  wishes  to  obtain  reputation 
as  an  author,  let  him  publish  an  original  work,  and  not  attempt  to  gain 
popularity  by  illustrating  and  enlarging  the  labours  of  another. 

Since  the  English  edition  of  Cruveilhier  has  been  published  in  Lon- 
don, the  first  and  second  volumes  of  a  second  edition  of  the  work  have 
been  published  by  the  author  in  Paris.  The  editor  has  carefully  com- 
pared the  second  edition  with  the  fi»st,  so  far  as  it  has  been  published, 
and  has  incorporated  in  the  American  edition  whatever  he  thought 
could  increase  its  value.  He  has,  however,  only  followed  the  second 
edition  when  he  thought  that  the  changes  introduced  were  improve- 
ments. In  many  instances,  with  the  view  of  keeping  down  the  size  o^ 
the  book,  he  has  condensed  into  a  few  short  paragraphs  the  substance 
of  several  pages.  In  the  department  of  Myology  the  author  has  in 
his  second  edition  made  very  numerous  alterations  from  the  first.  As 
these,  in  the  opinion  of  the  editor,  have  rather  diminished  than  in- 
creased the  value  of  the  work,  he  has  only  in  a  very  few  instances  adopt- 
ed them.  The  student,  he  feels  satisfied,  will  find  the  description  of  the 
muscles  sufficiently  minute.  The  subdivisions  introduced,  and  the 
minutiae  which  are  added  to  their  descriptions  in  the  second  edition. 


EDITOR  :>    l'Rt:rACF 


would  tend  rather  to  embarrass  than  to  piuiuure  their  improvement; 
he  has,  therefore,  very  generally  preferred  to  follow  the  first  edition 
in  the  description  of  the  muscles. 

In  the  original  work  there  are  no  engravings  ;  this  is  a  great  desidera- 
tum, which  has  been  removed  in  the  English  edition  by  the  introduc- 
tion of  numerous  woodcuts,  selected  with  care  from  the  best  anatomi- 
cal engravings,  and  marked  with  letters  of  reference.  This  greatly 
enhances  the  value  of  the  work.  The  translation,  which  is  an  excel- 
lent one,  was  made  by  Dr.  Madden. 

Systems  of  Anatomy  generally  offer  little  interest  except  to  the 
anatomical  student.  This  cannot  be  said  of  the  system  of  Anatomy  of 
Cruveilhier.  It  imbodies  a  fund  of  information,  in  connexion  with 
Physiology  and  Pathology,  which  will,  in  the  opinion  of  the  editor,  pro- 
cure for  it  a  place  in  the  library  of  every  physician  and  surgeon  who 
feels  any  interest  in  his  profession.  If  the  members  of  the  profession 
only  procure  the  book  and  peruse  it,  he  cannot  doubt  but  that  the 
cause  of  Anatomical  science  will  be  greatly  promoted  in  the  United 
States ;  and  should  this  be  the  case,  the  editor  will  be  amply  repaid  for 
any  trouble  he  may  have  had  in  undertaking  the  republication  of  Cru- 
veilhier. 

University  of  New-York,  Sept.  Ist,  l^A^. 


k 


AUTHOR'S   PREFACE. 

The  study  of  man  offers  three  very  different  objects  for  contemplation ;  viz.,  his  or- 
ganization, his  vital  functions,  and  his  moral  and  intellectual  faculties. 

The  organization  or  structure  of  man  is  the  object  of  anatomy,  a  science  which  in- 
vestigates every  distinguishable  material  condition  of  the  different  parts  that  enter  into 
the  construction  of  his  frame.  Anatomy  is  a  science  of  observation,  and  is,  in  this  re- 
spect, susceptible  of  mathematical  precision  and  physical  certainty. 

The  vital  functions  of  man  are  the  objects  of  physiology,  which  reveals  to  us  the  ac- 
tions of  organs,  with  whose  structure  anatomy  has  previously  made  us  acquainted.  The 
science  of  physiology  inquires  into  the  various  motions  that  occur  within  the  human 
body,  just  as  anatomy  investigates  the  form  of  its  component  parts.  All  that  we  know, 
in  fact,  concerning  material  objects,  may  be  resolved  into  a  knowledge  of  their  motions 
and  their  forms. 

As  a  moral  and  intellectual  being,  man  is  the  object  of  the  science  of  psychology, 
which  contemplates  him  in  the  exercise  of  thought  and  volition,  analyzes  the  operations 
of  his  mind  and  will,  and  classifies  them  according  to  their  supremacy. 

A  perfect  acquaintance  with  man  necessarily  presupposes  a  combination  of  all  that  is 
taught  by  these  three  sciences  ;  and  it  is  because  his  anatomy,  his  physiology,  and  his 
moral  and  intellectual  endowments  have  not  been  studied  by  the  same  class  of  philoso- 
phers, that  in  the  sciences  relating  to  himself  so  much  yet  remains  to  be  desired. 

Anatomy — the  immediate  object  of  this  work — constitutes  the  foundation  of  medicine. 
In  order  to  discover  the  precise  seat  of  a  defect  in  some  complicated  machine,  and  the 
means  to  be  adopted  for  the  reparation  of  its  disordered  mechanism,  it  is  necessary  to 
be  acquainted  with  the  relative  importance,  and  the  particular  action  of  all  its  constitu- 
ent parts.  "  The  human  body,"  says  Bacon,  "  may  be  compared,  from  its  complex  and 
delicate  organization,  to  a  musical  instrument  of  the  most  perfect  construction,  but  ex- 
ceedingly liable  to  derangement."  And  the  whole  science  of  medicine  is  therefore  re- 
duced to  a  knowledge  of  the  means  by  which  that  harmonious  instrument,  the  human 
frame,  may  be  so  tuned  and  touched  as  to  yield  correct  and  pleasing  sounds. 

But  since  anatomy  forms,  as  it  were,  the  vestibule  of  medical  science,  it  is  of  im- 
portance that  he  who  is  entering  upon  its  pursuit  should  fully  understand  the  path  he  is 
about  to  tread ;  it  is  necessary,  therefore,  to  assign,  on  the  one  hand,  the  rank  which 
medicine  holds  as  a  natural  science,  and,  on  the  other,  the  position  of  anatomy  among 
the  various  sciences  relating  to  medicine. 

The  term  science,  according  to  the  admirable  definition  of  the  Roman  orator,  signifies 
certain  knowledge,  deduced  from  certain  principles — cognitio  certa  ex  principiis  certis  ex- 
orta.  Sciences  are  divided  into  the  metaphysical,  the  mathematical,  and  the  natural ;  but 
since  the  two  former  are  not  connected  with  our  present  subject,  we  shall  direct  atten- 
tion to  the  natural  sciences  only. 

The  object  of  the  natural  sciences,  or  of  physics,  taken  in  its  widest  signification,  is  a 
knowledge  of  the  materials  of  which  the  universe  is  composed,  and  of  the  laws  by  which 
they  are  governed.  They  are  subdivided  into  the  physical,  and  the  physiological  or  zoo- 
logical. 

The  physical  sciences  take  into  consideration  all  the  phenomena  presented  by  inor- 
ganic bodies;  they  comprise,  1.  Astronomy,  which  studies  the  heavenly  bodies  as  they 
revolve  in  space,  and  estimates,  by  the  aid  of  numbers,  the  laws  by  which  their  move- 
ments are  governed ;  2.  Physics,  properly  so  called,  or  the  study  of  the  properties  of 
matter  in  general ;  in  aid  of  which,  experiments  are  performed  in  order  to  exhibit  phe- 
nomena in  every  possible  light,  and  calculation  is  employed  to  render  fruitful  the  results 
of  experiment ;  3.  Geology,  or  that  science  which  studies  the  surface  of  the  globe,  and 
the  successive  strata  which  are  met  with  in  its  interior ;  which  goes  back  far  beyond  all 
historical  traditions,  brings  to  light,  as  it  were,  the  very  depths  of  the  earth,  and  traces, 
with  a  sure  hand,  the  history  of  the  globe,  and  the  various  revolutions  it  has  undergone  ; 
4.  Chemistry,  which  consists  in  the  study  of  the  reciprocal  actions  of  bodies,  when  re- 
duced to  their  atomic  condition. 

The  zoological  or  physiological  sciences  embrace  all  the  phenomena  presented  by  living 
bodies.  The  science  of  botany  examines  into  the  structure  and  functions  of  plants ;  but 
zoology,  properly  so  called,  investigates  the  organization  and  the  life  of  animals.  The 
examination  into  structure  or  organization  constitutes  anatomy.  Physiology  embraces 
the  study  of  functions  or  of  life. 

The  facts  presented  to  us  in  the  zoological  are  of  a  totally  different  character  from 
those  comprised  in  the  physical  sciences,  Inorganic  bodies,  in  fact,  are  governed  by 
constant  and  immutable  laws,  acting  in  perfect  harmony  with  each  other ;  but  living 
bodies  are  subject  not  only  to  physical,  but  also  to  vital  laws,  the  latter  of  which  are 
constantly  struggling  against  the  former.  This  struggle  constitutes  life ;  death  is  the 
triumph  of  the  physical  over  the  vital  laws.  In  consequence,  however,  of  this  continual 
strife,  derangements  of  structure  and  disordered  functions  very  often  occur ;  and  these 
become  more  frequent  and  more  complicated,  in  proportion  as  the  organization  is  more 
highly  developed,  and  the  animal  more  elevated  in  the  scale  of  creation. 

A  knowledge  of  these  derangements  and  of  the  proper  means  for  restoring  both  or 


vui  author's  preface. 

ganization  and  life  to  a  healthy  condition,  constitutes  the  science  of  medicine ;  and  the 
station  which  I  have  just  assigned  to  this  most  important  branch  of  zoological  science 
will  prove,  better  than  any  arguments,  that  the  study  of  the  physiological  or  healthy 
state  of  organization  and  of  life  should  precede  that  of  their  pathological  or  diseased 
conditions  ;  and  that  anatomy  forms  the  first  link  in  the  chain  of  medical  science. 

Each  science  has  its  own  methods  of  investigation,  and  its  peculiar  elements  of  cer- 
tainty. Metaphysics  and  moral  philosophy  have  a  metaphysical  and  moral  certainty. 
The  mathematical  sciences  set  out  from  a  small  number  of  self-evident  propositions  or 
axioms  founded  upon  the  nature  of  things,  proceed  gradually  from  the  known  to  the  un- 
known, and  trust  to  problems  already  demonstrated  as  to  so  many  axioms,  by  means  of 
which,  as  steps,  they  again  ascend  towards  new  truths.  The  natural  sciences,  again, 
are  founded  upon  observation,  and  observation  is  merely  the  evidence  of  our  senses ; 
hence  arises  the  necessity  of  exercising  them,  in  order  to  increase  their  acuteness  and 
their  activity.  Facts,  therefore,  constitute  the  elements  of  the  natural  sciences  ;  and 
then  reasoning  follows,  founded  upon  those  facts  and  upon  analogy.  It  would  be  absurd 
to  study  the  natural  sciences  after  the  same  method  as  metaphysics. 

It  may  readily  be  understood,  that  as  the  purely  physical  sciences  are  based  upon  con- 
stant phenomena,  mathematics  are  directly  applicable  to  them,  and  hence  they  are  termed 
physico-mathematical  sciences;  but  in  the  zoological  sciences,  effects  are  continually 
varying,  according  to  their  causes.  Any  attempts,  therefore,  to  apply  the  art  of  numbers 
to  the  elements  of  medicine,  would  be  to  imitate  the  philosopher,  Condorcet,  who  enter- 
tained the  whimsical  notion  of  subjecting  moral  probabilities  to  the  test  of  mathematical 
precision ;  who  was  anxious  to  substitute  a-\-b  for  either  oral  or  written  legal  testimony ; 
who  admitted  half  proofs  and  fractional  proofs,  and  then  reduced  them  to  equations,  by 
means  of  which  he  supposed  he  could  arrive  at  arithmetical  decisions,  regarding  the 
lives,  the  fortunes,  and  the  characters  of  his  fellow-men. 

It  must,  however,  be  reluctantly  confessed,  that  we  can  acquire  a  knowledge  only  of 
the  surfaces  of  a  body ;  and  that  to  say  we  are  acquainted  with  its  texture,  is  to  state, 
in  other  words,  that  we  have  a  knowledge  of  the  smallest  surfaces  comprised  within  its 
general  surface.  Sight,  touch,  &c.,  the  only  means  of  investigation  by  which  we  can 
appreciate  the  qualities  of  matter  in  general,  can  recognise  nothing  but  surfaces,  appear- 
ances, and  relative  properties.  Absolute  properties  they  are  unable  to  detect.  With  our 
organization,  we  shall  never  know  of  what  material  objects  essentially  consist,  but  only 
what  they  are  in  relation  to  ourselves. 

This  work  being  essentially  of  an  elementary  nature,  and  in  some  measure  adapted 
for  the  lecture-room,  I  have  endeavoured  to  confine  myself  within  narrow  limits,  and 
strictly  to  avoid  all  considerations  which  are  not  inunediately  connected  with  the  anato- 
my of  organs.  At  the  same  time  I  have  not  forgotten  that  this  work  was  intended  for 
the  student  of  medicine,  and  not  for  the  naturalist ;  I  have,  therefore,  been  induced,  in 
the  following  pages,  if  not  expressly  to  indicate,  at  least  to  direct  attention  to  the  more 
immediate  applications  of  anatomy  to  physiology,  surgery,  and  medicine. 

The  objects  which  I  have  constantly  had  in  view  have  been  to  exhibit  the  actual  state 
of  the  science  of  anatomy ;  to  present  its  numerous  facts  in  their  most  natural  order  ; 
to  describe  each  fact  clearly,  precisely,  and  methodically ;  to  adopt  such  a  method  as 
would  form  an  easy  guide  to  the  student,  and  not  involve  him  in  confusion  ;  and,  lastly, 
to  give  to  each  detail  its  peculiar  value,  by  invariably  directing  particular  attention  to 
the  more  important  points,  instead  of  confounding  them  with  matters  of  less  consequence, 
in  an  indigested  and  monotonous  enumeration  of  facts. 

The  following  is  the  order  in  which  the  principal  divisions  of  the  subject  have  been 
treated. 

The  first  division  comprises  Osteology,  Arthrology  or  Syndesmology,  and  Odontology. 

1.  Osteology,  which,  notwithstanding  the  great  number  of  works  on  the  subject,  seema 
always  to  offer  some  new  facts  to  those  who  study  it  with  zeal,  has  been  treated  with 
the  attention  it  deserves,  as  forming  the  basis  of  anatomical  knowledge.  An  account 
of  the  development  of  the  osseous  system  has  appeared  to  me  necessary  for  the  comple- 
tion of  its  history.  I  have  therefore  considered  the  following  points  in  connexion  with 
the  development  of  each  bone  :  the  number  of  ossific  points ;  the  time  of  appearance  of 
the  primitive  and  complementary  ossific  points  ;  the  periods  at  which  the  several  points 
unite,  and  the  changes  occurring  in  the  bone  subsequently  to  its  growth.  By  adopting 
this  method,  the  most  complicated  ossifications  are  reduced  to  a  few  propositions  easily 
retained  in  the  memory. 

The  inconvenience  arising  from  including  in  a  description  of  the  bones  all  the  attach- 
ments of  the  muscles,  and  nearly  the  whole  anatomy  of  the  part,  is  so  totally  at  variance 
with  a  methodical  arrangement  of  facts,  that  it  is  unnecessary  to  offer  an  apology  for  the 
changes  made  in  this  respect.  Occasionally,  however,  I  have  mentioned  those  muscu- 
lar attachments  which  might  serve  to  characterize  the  osseous  surfaces  on  which  they 
are  situated. 

2.  Under  the  title  of  Syndesmology,  or  Arthrology,  are  united  all  the  articulations  of 
the  human  body.  Assummg  as  the  only  basis  of  classification  the  form  of  the  articula- 
ted surfaces,  which  is  always  in  aocordanoc  with  the  means  of  union  and  tlic  movements 
of  tlie  joint.  I  have  bnen  iu'liieofl  tn  mo  lify  thi-  division.'^  nsuallv  adopted.    Tlic  runilt'Li- 


AUTHOR  S   PREFACE.  IX 

throsis,  or  comyloid  arliculaium,  and  the  articulation  by  mutiial  reception,  form  quite  as 
natural  genera  as  the  enarthrosis  and  the  arthrodia.  It  will,  perhaps,  be  found  that  the 
characters  of  the  different  kinds  of  articulation,  and  in  particular  those  of  the  anpxlar 
ginglymus,  which  I  have  called  the  trochlear  articulation,  and  those  of  the  lateral  gingly- 
mus,  or  the  trochoid  articulation  of  the  ancients,  are  more  clearly  defined  than  in  other 
anatomical  works. 

The  mechanism,  t.  e.,  the  movements  of  a  joint,  is  so  intimately  connected  with  its 
anatomy,  that  it  was  impossible  to  pass  it  over  in  silence  ;  on  the  other  hand,  it  was 
sometimes  difficult  to  determine  the  limit  which  ought  to  distinguish  an  anatomical  from 
a  physiological  treatise.  I  have  endeavoured  to  avoid  both  extremes,  by  confining  my- 
self strictly  to  the  mechanism  of  each  joint  in  particular,  referring  to  works  on  physiol- 
ogy for  the  principal  movements  of  locomotion,  and  of  animal  statics,  such  as  waUiing, 
running,  standing,  &c. 

3.  Odontology,  or  the  description  of  the  teeth,  concludes  the  first  division.  I  have  ta- 
ken care  to  point  out  that  this  juxtaposition  of  the  bones  and  the  teeth  was  founded  upon 
their  common  indestructibility,  and  not  upon  the  identity  of  their  nature  ;  the  bones  be- 
ing organs  composed  of  living  tissues,  while  the  hard  portion  of  the  teeth,  on  the  other 
hand,  is  but  the  solidified  product  of  secretion.* 

The  second  division  includes  Myology,  Aponeurology,  and  Splanchnology. 

1.  In  treating  of  Myology,  I  have  preferred  the  topographical  to  the  physiological  ar- 
rangement of  the  muscles,  for  this  reason  only,  that  it  admits  of  all  of  them  being  studied 
upon  the  same  subject.  To  unite,  as  far  as  was  practicable,  the  undoubted  advantages 
possessed  by  both  methods,  I  have  given,  at  the  conclusion  of  myology,  a  general  sketch 
of  the  muscles,  arranged  according  to  their  physiological  relations ;  and  by  grouping 
them,  not  after  their  order  of  super-imposition,  but  according  to  their  several  actions,  I 
have  arranged  them  around  the  articulations  to  which  they  may  belong,  and  have  point- 
ed out  the  extensors,  the  flexors,  &c. 

A  muscle  being  known  when  its  attachments  are  ascertained,  I  have  thought  it  advi- 
sable to  commence  the  description  of  each  by  a  brief  announcement  of  its  origin  and  in- 
sertion, as  a  sort  of  definition  or  summary.  The  particular  details  concerning  its  mode 
of  insertion,  whether  it  be  aponeurotic  or  fleshy,  and  concerning  the  direction  of  its  fibres, 
complete  the  description  of  each  muscle  considered  by  itself ;  the  history  of  which  is 
concluded  by  an  examination  of  its  relations  to  neighbouring  parts,  and  of  its  uses.  The 
individual  or  combined  action  of  the  muscles,  for  the  production  of  simple  movements, 
follows  so  naturally  after  their  description,  and  presupposes  so  correct  and  positive  a 
knowledge  of  their  anatomy,  that  it  can  be  treated  of  with  propriety  only  in  a  work  on 
anatomy.  The  compound  movements  necessary  for  the  consecutive  or  simultaneous 
action  of  a  great  number  of  muscles  come  within  the  province  of  physiology. 

2.  The  aponeuroses,  those  important  appendages  of  the  muscular  system,  are  separ- 
ately noticed,  in  connexion  with  the  muscles  to  which  they  belong ;  but  I  have  also  de- 
scribed them  together  under  the  head  of  Aponeurology.  This  combination  of  analogous 
parts  possesses  the  twofold  advantage  of  simplifying  the  science,  by  enabling  one  part 
to  elucidate  the  structure  of  another,  and  of  permitting  us  to  discover  the  general  laws 
according  to  which  these  structures  are  disposed. 

3.  With  some  modification,  I  have  adopted  that  old  division  of  anatomy,  which  treats 
of  the  viscera  and  organs,  and  which  is  known  by  the  name  of  Splanchnology. 

The  brain  and  the  organs  of  the  senses,  which  were  included  in  this  division  in  all 
anatomical  works  preceding  those  of  Soemmering  and  Bichat,  have  been  removed  from 
it,  and  described  with  the  other  portions  of  the  nervous  system.  The  description  of  the 
heart,  in  like  manner,  will  be  found  with  that  of  the  other  organs  of  circulation.  In 
short,  the  old  classification  of  the  viscera,  according  to  their  locality,  that  is,  into  those 
of  the  head,  the  neck,  the  chest,  &c.,  has  been  replaced  by  a  more  physiological  arrange- 
ment. Splanchnology  will  therefore  comprehend  a  description  of  the  organs  of  digestion 
and  their  appendages,  of  the  organs  of  respiration  (among  which  is  included  the  larynx, 
or  the  organ  of  voice),  and,  lastly,  the  genito-urinary  organs. 

To  the  inquiry  why  I  have  departed  from  the  usual  custom  of  placing  splanchnology 
at  the  end  of  anatomy,  I  reply  that,  in  order  to  study,  with  advantage,  the  vessels  and 
the  nerves,  it  is  necessary  to  have  a  previous  acquaintance  with  the  organs  to  which 
they  are  distributed. 

The  importance  of  the  parts  described  in  this  division,  and  the  practical  results  which 
flow  from  even  the  most  superficial  knowledge  of  their  forms,  connexions,  and  intimate 
structure,  are  at  once  my  reason  and  excuse  for  extending,  to  so  great  a  length,  this 
portion  of  the  work ;  and,  moreover,  it  is  necessary  to  state,  that  there  are  many  medi- 
cal practitioners  who  learn  anatomy  only  from  elementary  works. 

The  third  and  the  last  division  treats  of  the  organs  of  circulation,  viz.,  the  heart,  arter- 
ies, veins,  and  lymphatics  ;  and  of  the  sensory  apparatus,  viz.,  the  organs  of  the  senses, 
the  brain,  and  the  nerves. 

1 .  No  part  of  anatomy,  perhaps,  has  been  better  known  than  the  arteries,  since  the 
appearance  of  Haller's  admirable  works ;  I  could  neither  have  followed  a  better  guide 
nor  a  more  perfect  model. 

*   See  n.ilr.  n.   1S3. 

u 


X  author's  peeface. 

2.  The  study  of  the  vei?is  has  acquired  an  unexpected  degree  of  importance,  in  conse- 
quence of  the  works  of  various  physicians  on  phlebitis  ;  and  our  knowledge  of  them  has 
been  mucli  extended  by  the  researches  of  M.  Dupuytren  into  the  veins  of  the  spine,  and 
the  excellent  plates  of  this  order  of  vessels  published  by  M.  Breschet. 

3.  The  study  of  the  lymphatics  has  been  almost  abandoned  since  the  very  remarkable 
publications  of  Mascagni :  I  have  endeavoured  to  ascertain  what  credit  was  to  be  given 
to  the  assertions  of  some  modern  writers  concerning  the  frequent  communication  be- 
tween the  veins  and  the  lyniphatics. 

4.  The  work  of  Soemmering  on  the  organs  of  the  senses  constitutes,  perhaps,  the  high- 
est title  to  fame  possessed  by  that  great  anatomist ;  and  it  might  even  be  said  that  he 
has  left  nothing  for  his  successors  to  accomplish,  did  not  the  constant  study  of  a  science 
of  observation  unceasingly  proclaim  this  important  truth,  that  it  is  in  the  power  of  no 
man  to  declare,  beyond  this  limit  thou  shalt  not  pass. 

The  brain  and  the  nerves,  to  which  so  many  able  and  laborious  inquirers  have  lately 
directed  their  attention,  have  been  my  favourite  objects  of  investigation  ;  on  account  of 
their  importance,  and  perhaps,  also,  from  the  difficulties  attending  their  study.  Not  sat- 
isfied with  simply  tracing  the  nerves  to  the  various  organs  in  the  body,  I  have  studied 
them  in  the  interior  of  those  organs,  and  have  endeavoured  to  ascertain  the  precise 
branches  that  are  distributed  to  each  particular  part. 

I  may  add,  that,  in  order  to  facilitate  the  dissection  of  the  nervous  system,  and,  indeed, 
of  all  the  other  parts  of  the  body,  I  have  presented,  whenever  it  was  necessary,  a  short 
account  of  the  best  method  of  preparation. 

With  regard  to  the  general  spirit  of  this  work,  I  have  been  anxious  to  render  it  clas- 
sical ;  and  have  avoided,  most  scrupulously,  that  species  of  induction  and  analogical  rea- 
soning, which,  in  a  great  measure,  constitutes  philosophical  anatomy.  To  this  kind  of 
anatomy  I  have  never  even  introduced  any  allusions,  except  when  its  general  ideas  and 
views  (almost  always  ingenious,  but  usually  bold  and  speculative)  might  elucidate  our 
own  subjects. 

All  the  descriptions  have  been  made  from  actual  dissections.  It  was  only  after  hav- 
ing completed  from  nature  the  account  of  each  organ  that  I  consulted  writers,  whose 
imposing  authority  could  then  no  longer  confine  my  thoughts,  but  always  excited  me  to 
renewed  investigations  wherever  any  discrepancy  existed. 

Anatomy  being,  as  already  stated,  the  basis  of  medical  science,  we  should  greatly 
misapprehend  its  nature  did  we  not  consider  it  the  chief  of  the  accessory  sciences  of 
medicine. 

Without  it,  the  physiologist  rears  his  structure  upon  sand  ;  for  physiology  is  nothing 
more  than  the  interpretation  of  anatomy.  It  is  anatomy  that  guides  the  eye  and  the 
hand  of  the  surgeon  ;  that  inspires  him  with  that  ready  confidence,  which  leads  him  to 
search  among  structures,  whose  lesion  would  be  dangerous  or  mortal,  for  some  vessel 
that  must  be  tied,  or  for  a  tumour  which  must  be  extirpated.  Nor  is  it  less  indispensa- 
ble to  the  physician,  to  whom  it  reveals  the  seat  of  diseases,  and  the  changes  of  form, 
size,  relation,  and  texture,  which  the  affected  organs  have  undergone. 

Anatomy  is,  moreover,  the  science  which,  of  all  others,  excites  the  greatest  curiosity. 
If  the  mineralogist  and  the  botanist  are  so  eager,  the  one  to  determine  the  nature  of  a 
stone,  the  other  to  ascertain  the  characters  of  a  flower  ;  if  the  love  of  their  particular 
science  induces  them  to  undertake  the  most  dangerous  voyages,  in  order  to  enrich  it 
with  a  new  species,  what  ought  to  be  our  ardour  in  pursuing  the  study  of  man,  that 
masterpiece  of  creation,  whose  structure,  possessed  of  both  delicacy  and  strength,  ex- 
hibits so  much  harmony  as  a  whole,  and  displays  so  much  perfection  in  its  parts  ! 

And  while  contemplating  this  marvellous  organization,  in  which  all  has  been  provided 
and  prearranged  with  such  intelligence  and  wisdom,  that  no  single  fibre  can  acquire  the 
slightest  addition,  or  undergo  the  least  diminution  of  power,  without  the  equilibrium  be- 
ing destroyed  and  disorder  being  induced — what  anatomist  is  there  who  would  not  feel 
tempted  to  exclaim,  with  Galen,  that  a  work  on  anatomy  is  the  most  beautiful  hymn 
which  man  can  chant  in  honour  of  his  Creator  !* 

May  this  work  inspire  among  students  an  ever-increasing  ardour  for  the  study  of  the 
organization  of  man,  which,  even  if  it  were  not  the  most  eminently  useful,  would  still 
be  the  most  interesting,  and  the  most  beautiful  of  all  the  sciences.  And  what  more 
powerful  motive  for  emulation  can  present  itself  to  a  generous  mind,  than  the  idea, 
"that  every  acquisition  of  knowledge  is  a  conquest  achieved  for  the  relief  of  suffering 
humanity  !"  Let  it  never  be  forgotten  that,  without  anatomy,  there  is  no  physiology,  no 
surgery,  no  medicine  ;  that,  in  a  word,  all  the  medical  sciences  are  grafted  upon  anato- 
my as  upon  a  stock ;  and  that  the  deeper  its  roots  descend,  the  more  vigorous  will  be 
its  branches,  and  the  more  abundantly  laden  with  flowers  and  with  fruit. 

I  must  here  express  my  acknowledgments  to  M.  Chassaignac,  the  anatomical  assist- 
ant to  the  Faculty,  who  has  distinguished  himself  in  several  concours,  and  who  has  as- 
sisted me  with  the  greatest  zeal  in  the  execution  of  this  work. 

*  "  Sacrum  sermonem  quem  ego  Conditoris  nostri  verum  hyranum  compono,  existimoque  in  hoc  veram  esse 
pietatem,  non  si  tauroruni  hecatombas  ei  sacrificaverim.  et  casias,  aliaque  sexcenta  odoramenta  ac  unguenta 
suffumigaverim,  sod  si  noverini  ipse  primus,  deiude  ct  aliis  exposuerim  quffinam  sit  ipsius  sapicntia.quce  virtus. 
ciUii!  bomtas."— (Galen, De  usu  part.,  lib  iii.) 


CONTENTS. 


INTRODUCTION. 
Object  and  Division  of  Anatomy. — General  View  of  the  Human  Frame. — Apparatus  of  Sensation— of  lo- 
comotion—of  Nutrition— of  Reproduction. — General  Plan  of  tlie  Worli Page  1 

APPARATUS  OF  LOCOMOTION. 
OSTEOLOGY. 
Of  the  Bones  in  Oeneral. 
The  Bones— Importance  of  their  Study.— General  View  of  the  Skeleton. — Number  of  the  Bones.— Method 
of  Description.— Nomenclature.— Situation  in  general.— Direction.— Size,  Weight,  and  Density  of  Bones. 
— Figure. — Distinction  into  long,  broad,  and  flat  Bones. — Regions  of  Bones. — Eminences  and  Cavities. — 
Internal  Conformation. — Texture. — Development,  or  Osteogeny.— Nutrition 5 

The  Vertebral  Column. 

General  Characters  of  the  Vertebrse. — Characters  peculiar  to  the  Vertebrse  of  each  Region. — Characters 

proper  to  certain  Vertebrae. — Vertebree  of  the  Sacro-coccygeal  Region. — The  Vertebral  Column  in  general. 

— Development 18 

The  Scull. 

Composed  of  the  Cranium  and  Face. — Cranial  Bones — Occipital — Frontal — Sphenoid — CEthmoid — Parietal 

— Temporal. — The  Cranium  in  general. — Development. — Bones  of  the  Face— Superior  Maxillary. — Palate. 

— Malar. — Nasal. — Lachrymal — Inferior  turbinated. — Vomer— Inferior  Maxillary. — The  Face  in  general. 

— Cavities. — Development 33 

The  Thorax,  or  Chest. 

The  Sternum.— Ribs.— Costal  Cartilages.— The  Thorax  in  general.— Development 64 

The  Superior,  or  Thoracic  Extremities. 
The  Shoulder.— Clavicle.— Scapula.— The  Shoulder  in  general.— Development.— Humerus.— Ulna.— Radius. 
—The  Hand— The  Carpus  and  Carpal  Bones.— The  Metacarpus  and  Metacarpal  Bones.— The  Fingers.— 
General  Development  of  the  Superior  Extremities 73 

The  Inferior,  or  .Abdominal  Extremities. 

The  Haunch.— Os  Coxse.— The  Pelvis.— Development.— Femur.— Patella.— Tibia.— Fibula.— The  Foot.— 
The  Tarsus  and  Tarsal  Bones. — The  Metatarsus  and  Metatarsal  Bones.— The  Toes. — Development  of  the 
Lower  ExUemities. — Comparison  of  the  Upper  and  Lower  Extremities. — Os  Hyoides    .        .       .        .87 

The  .Articulations,  or  Arthrology. 

General  Observations. — Articular  Cartilages. — Ligaments. — Synovial  Membranes. — Classification  of  the 

Joints,— Diarthroses. — Synarthroses. — Amphiarthroses,  or  Symphyses Ill 

.Articulations  of  the  Vertebral  Column. 
Articulations  of  the  Vertebra  with  each  other. — Those  peculiar  to  certain  Vertebra;. — Sacro-vertebral.  Sa- 
cro-coccygeal, and  Coccygeal  Articulations. — Articulations  of  the  Cranium— of  the  Face — of  the  Tho- 
rax        115 

Articulations  of  the  Superior  or  Thoracic  Extremities. 
Articulations  of  the  Shoulder. — Scapulo-humeral. — Humero-cubital. — Radio-cubital. — Radio-carpal. — Of 
the  Carpus  and  Metacarpus. — Of  the  Fingers 135 

Articulations  of  the  Inferior  or  Abdominal  Extremities. 

Articulations  of  the  Pelvis.— Coxo-femoral. — Knee-joint.— Peroneo-tibial. — Ankle-joint.— Of  the  Tarsus.— 

Tarso-metatarsal. — Of  the  Toes 154 

ODONTOLOGY. 
Circumstances  in  which  the  Teeth  differ  from  Bones. — Number. — Position.— External  Conformation.— Gen- 
eral Characters. — Classification— Incisor — Canine— Molar.— Structure. — Development .       .       .       .177 

MYOLOGY. 
The  Muscles  in  general. — Nomenclature. — Number. — Volume  and  Substance. — Figure. — Dissection. — Rela- 
tions.— Attachments. — Structure. — Uses. — Preparation. — Order  of  Description       .  .       .       .190 

Muscles  of  the  Posterior  Region  of  the  TVunk. 
The  Trapezius.— Latissimus  Dorsi  and  Teres  Major.— Rhomboideus. — Levator  Anguli  Scapula.- Serrati  , 

Postici. — Splenius. — Posterior  Spinal  Muscles. — Complexus. — Inter-spinales  Colli. — Recti  Capitis  Postici,  | 

Major  et  Minor. — Obliqui  Capitis,  Major  et  Minor. — General  View  and  Action  of  the  Posterior  Spinal 
Muscles 198 

Muscles  of  the  Anterior  Abdominal  Region. 
The  Obliquus  Externus  Abdominis. — Obliquuslntemus  and  Cremaster. — Transversalis  Abdominis. — Rectus 
Abdominis.— Pyramidalis 208 

Diaphragmatic  Region 212 

Lumbar  Region. 

The  Psoas  and  lUacus. — Psoas  Parvus. — Ciuadratus  Lumborum        .       . 214       ^ 

Lateral  Vertebral  Region. 
Tholnter-transversales  and  Rectus  Capitis  Lateralis.— Scaleni .217 


# 


XU  CONTENTS. 

Deep  Anterior  Cervical,  or  Prevertebral,  Region. 
The  Recti  Capitis  Antici,  Major  et  Minor.— Longus  Colli.— Action  of  these  Muscles        .       .       .  Page  318 

Thoracic  Region. 
The  Pectoralis  Major.— Pectoralis  Minor.— Sub-clavius.—Serratus  Magnus. — Intercostalei.— Supra-costales. 
— Infra-costales. — Triangularis  Sterni 220 

Superficial  Anterior  Cervical  Region. 

The  Platysma  Myoides. — Sterno-cleido-itiastoideus 234 

Muscles  of  the  Infra-hyoid  Region. 
The  Sterno-hyoideus. — Scapulo-  or  Omo-hyoideus. — Sterno-thyroideus. — Thyrohyoideus      .        .        .  5^ 

Muscles  of  the  Supra-hyoid  Region. 

The  Digastricus  — Stylo-hyoideus. — Mylo-hyoideus. — Genio-hyoideus.— Their  Action      ....  228 

Muscles  of  the  Cranial  Region. 

Occipito-frontalis. — Auricular  Muscles 230 

Muscles  of  the  Palpebral  Region. 
Orbicularis  Palpebrarum. — Superciliaris. — Levator  Palpebrae  Superioris    ....  .       .  231 

JVasal  Region. 
The  Pjramidalis  Nasi.— Levator  Labii  Superioris  Alaeque  Nasi.— TransTersalis,  or  Triangularis  Nasi^— De 
pressor  Alie  Nasi. — N^so-labialis 233 

Muscles  of  the  Labial  Region. 
The  Orbicularis  Oris. — Buccinator. — Levator  Labii  Superioris. — Caninus. — Zygontatici,  Major  et  Minor. 
Triangularis. — Quadratus  Menti. — Levator  Labii  Superioris. — Movements  of  the  Lips  and  those  of  the 
Face 234 

Muscles  of  the  Temporo-maxillary  Region. 

The  Masseter  and  Temporalis 339 

The  Pterygo-maxillary  Region. 

The  Pterygoideiu  Intemus. — The  Pterygoideus  Kxternus 240 

Muscles  of  the  Shoulder. 
The  Deltoideus. — Supraspinatus. — Infra-spinatug  and  Teres  Minor. — Sub-scapularis      ....  341 

Muscles  of  the  Arm. 

The  Biceps. — Brachialis  Anticus. — Coraco-brachialis. — ^Triceps  Extensor  Cubiti 244 

Muscles  of  the  Forearm 349 

Muscles  of  the  Hand. 
The  Abductor  Brevis  Pollicis. — Opponens  Pollicis. — Flexor  Brevis  Pollicis. — Adductor  PoIIicis. — Palmaris 
Brevis. — Abductor  Digit!  Minimi. — Flexor  Brevis  Digiti  Minimi. — Opponens  Digiti  Minimi. — ^The  Interos- 
seous Muscles,  Dorsal  and  Palmar 260 

Muscles  of  the  Pelvis. 

The  GIutsBi  Maximus,  Medius,  et  Minimus. — Pyriformis. — Obturator  Intemus. — Gemelli,  Superior  et  Inferior. 

^^iuadratus  Femoris. — Obturator  Extern  us. — Action  of  these  Muscles 364 

Muscles  of  the  Thigh. 
The  Biceps  Cruris. — Semi-tendinosus. — Semi-membranosus. — Tensor  Vagina  Femoris. — Sartorius. — Triceps 
Extensor  Cruris. — Gracilis. — Adductor  Muscles  of  the  Thigh 369 

Muscles  of  the  Leg. 
The  Tibialis  Anticus. — The  Extensor  Communis  Digitorum. — Extensor  Proprius  Pollicis. — Peronei  Longus 
et  Brevis. — Gastrocnemius,  Plantaris  and  Solaris. — Popliteus. — Tibialis  Posticus. — Flexor  Longus  Pol- 
licis        377 

Muscles  of  the  Fbot. 
The  Extensor  Brevis  Digitorum. — Abductor  Pollicis  Pedis. — Flexor  Brevis  Pollicis  Pedis. — Adductor  Pollicis 
Pedis. — Transveisus  Pollicis  Pedis. — Abductor  Digiti  Minimi.— Flexor  Brevis  Digiti  Minimi. — Flexor  Bre- 
vis Digitorum. — Flexor  Accessorius. — Lumbricales. — Interossei 386 

APONEUROLOGY. 

Geaeral  Observations  on  the  Aponeuroses. — Structure. — Uses 294 

Particular  Aponeuroses. 
Superficial  Fascia. — Aponeuroses  of  the  Cranium — of  the  Face — of  the  Neck — of  the  Thorax — of  the  Abdo- 
men—of  the  Pelvis — of  the  Thigh,  Leg,  and  Foot — of  the  Shoulder,  Arm,  Forearm,  and  Hand   .        .  397 

SPLANCHNOLOGY. 

General  Observations  on  the  Viscera.— External  Conformation.-     tructure.— Development.— Functions.— 
Dissection 330 

Tbk  Qsgans  of  Digestion  and  theik  Aitendages. 

Alimentary  or  Digestive  Canal. 
General  Observations. — Division. — Mouth  and  its  Appendages. — Lips.— Cheeks. — Hard  and  soft  Palate. — 
Tonsils. — Tongue. — Salivary  Glands. — Buccal  Mucous  Membrane. — Pharynx. — CEsophagus. — Stomach. — 
Small  Intestine. — Large  Intestine. — Muscles  of  the  Perineum. — Development  of  the  Intestinal  Canal  .  333 

Appendages  of  the  Alimentary  Canal. 
Tlie  Liver  and  its  Excretory  Apparatus.— The  Pancreas. — ^The  Spleen 384 

The  Organs  of  Respiration 
General  Observations.— The  Lungs  and  Pleura;.— The  Trachea  and  Bronchi.— Development  of  the  Lungs. 
—The  Larynx— its  Structure,  Development,  and  Functions.— The  Thyroid  Gland        ....  409 


CONTENTS.  XUl 

The  Genito-Urinaey  Organs. 

Tlie  Urinary  Organs. 
DiTiskw.— The  Kidneys  and  Ureters.— The  Bladder.— The  Supra-renal  Capsnles    .       .       .         Page  435 

The  Generative  Organs. 
The  Oenerative  Organs  of  the  Male. 
The  Testicles  and  their  Coverings.— The  Epididymis,  the  Vasa  Deferentia,  and  Vealcalsi  Seminallte.— The 
Penis.— The  Urethra.— The  Prostate  and  Cowper's  Glands 446 

The  Generative  Organs  of  the  Female. 
The  Ovaries.- The  FalloiMan  Tubes.— The  Uterus.— The  Vagina.— The  Urethra.— The  Vulva     .       .  461 

The  Mammte. 
Number.— Situation. — Size.— Form. — Structure.— Development 473 

The  Peritoneum. 
The  Sub-ombiUcal  Portion. — The  Supra-umbilical  Portion.— General  Description  and  Structure    .        .  479 

ANGEIOLOGY. 

Definition  and  Objects  of  Angeiology 479 

The  Heart. 
General  Description. — External  and  Internal  Conformation. — Structure. — Development.— Functions. — The 
Pericardium         . 479 

The  Arteries. 
Definition. — Nomenclature. — Origin. — Varieties. — Course. — Anastomoses. — Form  and  Relations. — Termina- 
tion.— Structure. — Preparation 496 

Description  of  the  Arteries. 

The  Pulmonary  Artery. 

Preparation. — Description. — Relations. — Size. — Development 499 

The  Aorta. 
Preparation.-Definition.— Situation. — Direction.— Size. — Division  into  the  Arch  of  the  Aorta,  the  Thoracic 

Aorta,  and  the  Abdominal  Aorta 501 

Collateral  Branches  of  the  Aorta. 
Ehiumeration  and  Classification. — Arteries  arising  from  the  Aorta  at  its  Origin,  viz.,  the  Coronary  or  Car- 
diac.^Arteries  arising  from  the  Thoracic  Aorta,  viz.,  the  Bronchial,  the  (Esophageal,  the  Intercostal.— 
Arteries  arising  from  the  Abdominal  Aorta,  viz.,  the  Lumbar,  the  Inferior  Phrenic,  the  CcBliac  Axis,  in- 
cluding the  Coronary  of  the  Stomach,  the  Hepatic,  and  the  Splenic,  the  Superior  Mesenteric,  the  Inferior 
Mesenteric,  the  Spermatic,  the  Renal,  and  the  Supra-renal  or  Capsular        .       .       .       .       .       .503 

Arteries  arising  from  the  Arch  of  the  Aorta. 
Enumeration  and  Varieties. — The  Common  Carotids. — ^The  External  Carotid — the  Superior  Thyroid — the 
Facial — the  Lingual — the  Occipital — the  Posterior  Auricular — the  Parotid — the  ascending  Pharyngeal — 
the  Temporal — the  Internal  Maxillary. — ^The  Internal  Carotid— the  Ophthalmic — the  Cerebral  Branches 
of  the  Internal  Carotid. — Summary  of  the  Distribution  of  the  Common  Carotids. — Artery  of  the  Upper 
Extremity.— The  Brachio-cephalic. — The  Right  and  Left  Sub-clavians— the  Vertebral  and  its  Cerebral 
Branches,  with  Remarks  on  the  Arteries  of  the  Brain,  Cerebellum,  and  Medulla — the  Inferior  Thyroid — 
the  Supra-scapular — the  Posterior  Scapular — the  Internal  Mammary — the  deep  Cervical — the  Superior 
Litercostal. — ^The  Axillary — the  Acromio-thoracic — the  Long  Thoracic — the  Sub-scapular — the  Posterior 
Circumflex— the  Anterior  Circumflex. — ^The  Brachial  and  its  Collateral  Branches. — The  Radial,  its  Col- 
lateral Branches,  and  the  deep  Palmar  Arch. — The  Ulnar,  its  Collateral  Branches,  and  the  Superficial 
Palmar  Arch. — General  Remarks  on  the  Arteries  of  the  Upper  Extremity 513 

Arteries  arising  from  the  Termination  of  the  Aorta. 
Enumeration. — The  Middle  Sacral.— The  Common  Iliacs. — The  Internal  Iliac,  or  Hypogastric — ^the  Umbil- 
ical— the  Vesical — the  middle  Haemorrhoidal — the  Uterine — the  Vaginal — the  Obturator — the  Ilio-lurabar 
—the  Lateral  Sacral — the  Glutsal — the  Sciatic — the  Internal  Pudic. — Summary  of  the  Distribution  of 
the  Internal  Iliac. — Artery  of  the  Lower  Extremity. — The  External  Iliac — the  Epigastric— the  Circumflex 
Iliac. — The  Femoral — the  Superficial  Epigastric — the  External  Pudic — the  Muscular — the  deep  Femoral, 
its  Circumflex  and  Perforating  Branches. — The  Popliteal,  and  its  Collateral  Branches. — The  Anterior 
Tibial  and  the  Dorsal  Artery  of  the  Foot. — The  Tibio-peronenl — Peroneal — Posterior  Tibial,  and  the  In- 
ternal and  External  Plantar. — Comparison  between  the  Arteries  of  the  Upper  and  Lower  Extremities  .  552 

The  Veins. 
Definition.— The  Venous  System. — Origin  of  the  Veins.— Course. — Anastomoses  and  Plexuses. — Varieties. 
— Termiaation. — Valves. — Structure. — Preparation. — Method  of  Description 573 

Description  op  the  Veins. 

The  Pulmonary  Veins 

Preparation.— Description.— Relations.— Size.— Peculiarities 577 

The  Veins  of  the  Heart. 
The  Great  Coronaiy  or  Cardiac  Vein.— The  Small  Cardiac  Veins 577 

The  Superior,  or  Descending  Vena  Cava  and  its  Branches, 
The  Superior  Vena  Cava. — The  Brachio-cephalic  Veins — the  Inferior  Thyroid — the  Internal  Mammary — 
the  Superior  Phrenic,  the  Thymic,  Pericardiac,  and  Mediastinal— the  Vertebral. — ^The  Jugular  Veins,  viz., 
the  External — the  Anterior — and  the  Internal. — The  Encephalic  Veins,  and  the  Sinuses  of  the  Diuu 
Mater,  viz.,  the  Lateral — the  Superior  Longitudinal — the  Straight — the  Superior  and  Inferior  Petrosal — 
the  Cavernous — the  Coronary — and  the  Anterior  and  Posterior  Occipital  Sinuses — the  Conflux  of  the 
Sinuses.— The  Branches  of  Origin  of  the  Jugular  Veins— the  Facial— tlie  Temporo-maxiilarv- the  Pos- 


k 


XIT  CONTENTS. 

terior  Auricular— the  Occipital— the  Lingual— the  Pharyngeal— the  Superior  and  Midcile  ThsToid— the 
Veins  of  the  Dipioe. — Summary  of  the  Distribution  of  the  Veins  of  the  Head. — The  deep  Veins  of  the 
Upper  Extremity — the  Palmar,  Radial,  Ulnar,  Brachial,  and  Axillary — the  Sub-clavian. — The  Superficial 
Veins  of  the  Upper  Extremity — in  the  Hand — in  the  Forearm — at  the  Elbow— €uid  in  the  Arm. — General 
Remarks  on  these  Superficial  Veins Page  578 

The  Inferior,  or  Ascending  Vena  Cava  and  its  Branches. 
The  Inferior  Vena  Cava — the  Lumbar  or  Vertebro-lumbar  Veins — the  Renal — the  Middle  Supra-renal — the 
Spermatic  and  Ovarian — the  Inferior  Phrenic. — The  Portal  System  of  Veins — the  Branches  of  Origin  of 
tlie  Vena  Porta— the  Vena  Portae  —  the  Hepatic  Veins.  —  The  Common  liiacs  —  the  Internal  Iliac  —  the 
Hemorrhoidal  Veins  and  Plexuses — the  Pelvic  Veins  and  Plexuses  in  the  Male  and  in  the  Female. — ^The 
deep  Veins  of  the  Lower  Extremity — the  Plantar,  Posterior  Tibial,  Peroneal,  Dorsal,  Anterior  Tibial,  and 
Popliteal — the  Femoral — the  External  Iliac. — The  Superficial  Veins  of  the  Lower  Extremity — the  Inter- 
nal Saphenous — the  External  Saphenous 596 

The  Veins  of  the  Spine. 
General  Remarks. — The  Superficial  Veins  of  the  Spine. — The  Anterior  Superficial  Spinal  Veins,  viz.,  the 
Greater  Azygos — the  Lesser  Azygos — the  Left  Superior  Vertebro-costals — the  Right  Vertebro-costals — 
the  Vertebro-lumbar — the  Ilio-lurabar,  and  Middle  and  Lateral  Sacral — the  Anterior  Superficial  Spinal 
Veins  in  the  Neck. — The  Posterior  Superficial  Spinal  Veins. — The  deep  Spinal  or  Intra-spinal  Veins — 
the  Anterior  Longitudinal,  and  the  Transverse  Veins  or  Plexuses,  and  the  Veins  of  the  Vertebrte  —  the 
Posterior  and  the  Posterior  and  Lateral  Transverse  Veins  or  Plexuses — the  Medullary  Veins. — General 
Remarks  on  the  Veins  of  the  Spine 605 

The  Lymphatic  System. 
Definition,  History,  and  general  View  of  the  Lymphatic  System.  —  Origin.  —  Course. — Termination  and 
Structure  of  the  Lymphatic  Vessels. — The  Lymphatic  Glands. — Preparation  of  the  Lymphatic  Vessels 
and  Glands 611 

Description  of  the  Lymphatic  System. 

The  Thoracic  Duct — the  Right  Thoracic  Duct. — The  Lymphatic  System  of  the  Lower  Extremity — of  t  e 
Pelvic  and  Lumbar  Regions — of  the  Liver — of  the  Stomach,  Spleen,  and  Pancreas— of  the  Intestines — of 
the  Thorax  —  of  the  Head  —  of  the  Cervical  Regions  —  of  the  Upper  Extremity  and  Upper  Part  of  the 
Trunk 620 

NEUROLOGY. 
The  Organs  of  the  Senses. 
The  Skin — its  External  Characters,  Structure,  and  Appendages. — The  Tongue  considered  as  the  Orgaa  of 
Taste. — The  Organ  of  Smell — the  Nose— the  Pituitary  Membrane. — The  Organ  of  Sight — the  Eyebrows 
—  the  Eyelids  —  the  Muscles  of  the  Orbit  —  the  Lachrymal  Apparatus  —  the  Globe  of  the  Eye,  its  Mem- 
branes and  Humours — the  Vessels  and  Nerves  of  the  Eye. — The  Organ  of  Hearing — the  External  Ear — 
the  Middle  Ear  or  Tympanum — the  Internal  Ear  or  Labyrinth — the  Nerves  and  Vessels  of  the  Ear    .  62fl 

The  Cerebro-spinal  Axis. 

General  Observations 681 

The  Membranes  of  the  Cerebro-spinal  Axis. 
General  Remarks. — The  Dura  Mater — the  Cranial  Portion,  its  Structure  and  Uses— the  Spinal  Portion. — 
The  Arachnoid — its  Cranial  Portion — its  Spinal  Portion — the  Sub-arachnoid  Fluid — their  Uses. — The  Pia 
Mater — its  External  Cerebral  Portion 682 

The  Spinal  Cord,  and  the  Medulla  Oblongata. 
General  View  of  the  Cord — its  Limits  and  Situation — the  Ligamentum  Denticulatum. — Size  of  the  Spinal 
Cord  —  Form,  Directions,  and  Relations  —  the  Cord  in  its  Proper  Membrane  —  the  Proper  Membrane,  or 
Neurilemma  of  the  Cord — the  Cord  deprived  of  its  Proper  Membrane. — Internal  Structure  of  the  Cord — 
Sections — Examination  by  means  of  Water,  and  when  hardened  in  Alcohol — the  Cavities  or  Ventricles 
of  the  Cord. — ^The  Medulla  Oblongata — Situation — External  Conformation — Anterior  Surface,  the  Ante- 
rior Pyramids  and  the  Olivary  Bodies — the  Posterior  Surface — the  Lateral  Surfaces — the  Internal  Struc- 
ture— Sections — Examination  by  Dissection,  and  under  Water. — Development  of  the  Spinal  Cord.— De- 
velopment of  the  Medulla  Oblongata. — Comparative  Anatomy  of  the  Spinal  Cord. — Comparative  Anatomy 
of  the  Medulla  Oblongata 693 

The  Isthmus  of  the  Encephalon. 

General  Description  and  Division. — The  Pons  Varolii  and  Middle  Peduncles  of  the  Cerebellum — the  Pedun- 
cles of  the  Cerebrum — the  Superior  Peduncles  of  the  Cerebellum  and  the  Valve  of  Vieussens — the  Cor- 
pora Quadrigemina. — Internal  Structure  of  the  Isthmus,  viz.,  of  its  Inferior,  Middle,  and  Superior  Strata. 
— Sections. — Development. — Comparative  Anatomy 710 

The  Cerebellum. 

General  Description. — External  Characters  and  Conformation — Furrows,  Lobules,  Lamins,  and  Lamellte. 
— Internal  Conformation — the  Fourth  Ventricle,  its  Fibrous  Layers,  its  Inferior  Orifice,  and  its  Choroid 
Plexus. — Sections  of  the  Cerebellum,  Vertical  and  Horizontal. — Examination  by  Means  of  Water,  and  of 
the  hardened  Cerebellum. — General  Viev%  nf  the  Organ. — Development. — Comparative  Anatomy      .  715 

The  Cerebrum,  or  Brain  Proper. 

Definition — Situation — Size  and  Weight — General  Form. — The  Superior  or  Convex  Surtice. — 1  ne  Inferior 
Surface  or  Base — its  Median  Region,  containing  the  Inter-peduncular  Space,  the  Corpora  Albicantia,  the 
Optic  Tracts  and  Commissure,  the  Tuber  Cinereum,  Infundibuluni,  and  Pituitary  Body,  the  Anterior  Part 
of  the  Floor  of  the  Third  Ventricle,  the  reflected  Part  of  the  Corpus  Callosum,  the  Anterior  Part  of  the 
Longitudinal  Fissure,  the  Posterior  Part  of  the  Longitudinal  Fissure,  the  Posterior  Extremity  of  the  Corpus 
Callosum  and  Median  Portion  of  the  Transverse  Fissiu-e,  and  the  Transverse  Fissure. — The  Lateral  Re- 
gions, including  the  Fissiu-e  of  Sylvius  and  the  Lobes  of  the  Brain. — The  Convolutions  and  Anfractuosi- 
ties  of  the  Brain,  upon  its  Inner  Surface,  its  Base,  and  its  Convex  Surface — Uses  of  the  Convolutions  and 
Anfractuosities. — The  Internal  Structure  of  the  Brain — Examination  by  Sections — Horizontal  Sections 
showing  the  Corpus  Callosum,  the  Septum  Luciduni,  the  Fornix  and  Corpus  Fimbriatum,  the  Velum  In- 
terpositum,  the  Middle  or  Third  Ventricle,  the  Aqueduct  of  Sylvius,  the  Pineal  Gland,  the  Lateral  Ven- 
tricle?, their  Superior  and  Inferior  Portions,  the  Choroid  Plexus,  and  the  Lining  Membrane  and  the  Fluid 
of  the  Ventriclus — Mrdlan  Vertical  Section — Transverse  Vertical  Sections — Section  of  Willis. — General 


CONTENTS.  XV 

Remirks  on  this  Method  of  examining  the  Brain.— Methods  of  Varolius,  Vienssens,  and  Gall.— Gall  and 
Spurzheim's  Views  on  the  Structure  of  the  Brain. — General  Idea  of  the  Brain.— Development. — Compar- 
ative Anatomy ...  Page  725 

The  Nerves,  ob  the  Peripheral  Portion  of  the  Nervous  System. 
General  Remarks. — History  and  Classification. — Origin,  or  Central  Extremity. — Different  Kinds. — Course, 
Plexuses,  and  Anastomoses. — Direction,  Relations,  and  Mode  of  Division. — Termination. — Nervous  Gan- 
glia, and  the  great  Sympathetic  System.— Conne.\ions  of  the  Ganglia  with  each  other,  and  with  the  Spi- 
nal Nerves.— Structure  of  Nerves.— Structure  of  Ganglia.— Preparation  of  Nerves        .        .        .        .759 

Description  of  the  Nerves. 

General  Remarks.— Division  into  Spinal,  Cranial,  and  Sympathetic  Nerves 769 

TVke  Spinal  JVerves. 
Enumeration  and  Classification. — ^The  Central  Extremities,  or  Origins  of  the  Spinal  Nerves — Apparent  Ori- 
gins— Deep  or  real  Origins. — The  Posterior  Branches  of  the  Spinal  Nerves — Common  Characters — the 
Posterior  Branches  of  the  Cervical  Nerves,  their  Common  and  Proper  Characters — the  Posterior  Branches 
of  the  Dorsal,  Lumbar,  and  Sacral  Nerves. — The  Anterior  Branches  of  the  Spinal  Nerves — their  General 
Arrangement 770 

The  interior  Branches  of  the  Cervical  JVerves. 
Dissection. — Anterior  Branch  of  the  First,  Second,  Third,  and  Fourth  Cervical  Nerves. — The  Cervical 
Plexus— its  Anterior  Branch,  the  Superficial  Cervical— its  Ascending  Branches,  the  great  Auricular  and 
the  External  or  Lesser  Occipital— its  Superficial  Descending  Branches,  the  Supra-clavicular— its  deep  De 
scending  Branches,  the  Nerve  to  the  Descendens  Noni  and  the  Phrenic — its  deep  Posterior  Branches. — 
The  Anterior  Branches  of  the  Fifth,  Sixth,  Seventh,  and  Eighth  Cervical,  and  First  Dorsal  Nerves. — The 
Brachial  Plexus — its  Collateral  Branches  above  the  Clavicle — its  Muscular  Branches,  Posterior  Thoracic, 
Supra-scapular — opposite  to  the  Clavicle  the  Thoracic,  below  the  Clavicle  the  Circumflex — its  Terminal 
Branches,  the  Internal  Cutaneous  and  its  Accessory,  the  Musculo-cutaneous,  the  Median,  the  Ulnar,  the 
Musculo-spiral  or  Radial. — Summary  of  the  Distribution  of  the  Branches  of  the  Brachial  Plexus        .  776 

The  interior  Branches  of  the  Dorsal  JVerves,  or  the  Intercostal  JVerves. 

Dissection. — Enumeration. — Common  Characters. — Characters  proper  to  each 794 

The  interior  Branches  of  the  Lumbar  JVerves. 

Enumeration.— The  Lumbar  Plexus.— Collateral  Branches,  Abdominal  and  Inguinal.— Terminal  Branches 
— the  Obturator  Nerve— the  Crural  Nerve  and  its  Branches,  viz.,  the  Musculo-cutaneous— the  Accessory 
of  the  Internal  Saphenous— the  Branch  to  the  Sheath  of  the  Vessels— the  Muscular  Branches— the  Inter- 
nal Saphenous 796 

The  Anterior  Branches  of  the  Sacral  M'erves. 

Dissection. — Enumeration. — The  Sacral  Plexus. — Collateral  Branches,  viz.,  the  Visceral  Nerves — the  Mus- 
cular Nerves  — the  Inferior  Hemorrhoidal  —  the  Internal  Pudic  and  its  Branches  — the  Superior  Gluteal 
Nerve— the  Inferior  Gluteal,  or  Lesser  Sciatic  Nerve — the  Nerves  for  the  Pyramidalis,  (iuadratus  Fe- 
moris,  and  Gemelli. — Terminal  Branch  of  the  Sacral  Plexus,  or  the  great  Sciatic  Nerve. — The  External 
Popliteal  and  its  Branches — the  Peroneal,  Saphenous,  Cutaneous,  and  Muscular  Branches — the  Musculo- 
cutaneous— the  Anterior  Tibial. — The  Internal  Popliteal  and  its  Branches — the  Tibial  or  External  Saphe- 
nous— Muscular  and  Articular  Branches — the  Internal  Plantar — the  External  Plantar. — Summary  of  the 
Nerves  of  the  Lower  Extremity. — Comparison  of  the  Nerves  of  the  Upper  with  those  of  the  Lower  Ex- 
tremity          804 

T%e  Cranial  JVerves. 

Definition  and  Classification. — ^The  Central  Extremities  of  the  Cranial  Nerves,  viz.,  of  the  Olfactory— of 

the  Optic — of  the  Common  Motor  Oculi — of  the  Pathetic — of  the  Trigeminal — of  the  External  Motor  Oculi 

— of  the  Portio  Dura  and  Portio  Mollis  of  the  Seventh — of  the  Glosso-pharyngeal,  Pneumogastric,  and 

Spinal  Accessory  Divisions  of  the  Eighth — and  of  the  Ninth  Nerves 816 

Distribution  of  the  Cranial  JVerves. 
The  First  Pair,  or  Olfactory  Nerves. — ^The  Second,  or  Optic  Nerves. — The  Third,  or  Common  Mdlor  Nerves. 
— The  Fourth,  or  Pathetic  Nerves. — The  Fifth,  or  Trigeminal  Nerves — the  Ophthalmic  Division  of  the 
Fifth,  and  its  Lachrymal,  Frontal,  and  Nasal  Branches — the  Ophthalmic  Ganglion — the  Superior  Maxil- 
lary Division  of  the  Fifth,  and  its  Orbital  Branch — the  Spheno-palatine  Ganglion,  and  its  Palatine,  Spheno- 
palatine, and  Vidian  Branches — the  Posterior  and  Anterior  Dental,  and  the  Terminal  Branches  of  the  Su- 
perior Maxillary  Nerve — the  Inferior  Maxillary  Division  of  the  Fifth — its  Collateral  Branches,  viz.,  the 
deep  Temporal,  the  Masseteric,  Buccal,  and  Internal  Pterygoid,  and  Auriculo-temporal — its  Terminal 
Branches,  viz.,  the  Lingual  and  Inferior  Dental — the  Otic  Ganglion. — The  Sixth  Pair,  or  External  Motor 
Nerves. — The  Seventh  Pair — the  Portio  Dura,  or  the  Facial  Nerve — its  Collateral  Branches — its  Terminal 
Branches,  viz.,  the  Temporo-facial  and  Cervico-facial — the  Portio  Mollis,  or  Auditory  Nerve. — The  Eighth 
Pair — its  First  Portion,  or  the  Glosso-pharyngeal'  Nerve — its  Second  Portion,  or  the  Pneumogastric  Nerve, 
divided  into  a  Cranial,  Cervical,  Thoracic,  and  Abdominal  Part— its  Third  Portion,  or  the  Spinal  Acces- 
sory Nerve.— The  Ninth  Pair,  or  the  Hypoglossal  Nerves.— General  View  of  the  Cranial  Nerves       .  824 

The  Sympathetic  System  of  JVerves. 
€eneral  Remarks.— The  Cervical  Portion  of  the  Sympathetic. — The  Superior  Cervical  Ganglion — its  Supe- 
rior Branch,  Carotid  Plexus,  and  Cavernous  Plexus — its  Anterior,  External,  Inferior,  and  Internal  Branch- 
es.—The  Middle  Cervical  Ganglion.  — The  Inferior  Cervical  Ganglion.  — The  Vertebral  Plexus.  — The 
Cardiac  Nerves ;  Right,  Superior,  Middle,  and  Inferior  ;  Left.— The  Cardiac  Ganglion  and  Plexuses.— The 
Thoracic  Portion  of  the  Sympathetic- The  External  and  Internal  Branches.— The  Splanchnic  Nerves, 
Great  and  Small.— The  Visceral  Ganglia  and  Plexuses  in  the  Abdomen,  viz.,  the  Solar  Plexus  and  Semi- 
lunar Ganglia.— The  Diaphragmatic  and  Supra-renal,  the  Coeliac,  the  Superior  Mesenteric,  the  Inferior 
Mesenteric,  and  the  Renal,  Spermatic,  and  Ovarian  Plexuses.— The  Lumbar  Portion  of  the  Sympathetic. 
—The  Communicating,  External,  and  Internal  Branches.— The  Lumbar  Splanchnic  Nerves  and  Visceral 
Plexuses  in  the  Pelvis.  —  The  Sacral  Portion  of  the  Sympathetic.  —  General  View  of  the  Sympathetic 
System 854 


DESCRIPTIVE  ANATOMY. 


INTRODUCTION. 

Object  and  Division  of  Anatomy. — General  View  of  the  Human  Frame. — Apparatus  of  Sen- 
sation— of  Locomotion — of  Nutrition — of  Reproduction. — General  Plan  of  the  Work. 

Considered  in  its  most  extended  signification,  Anatomy*  is  the  science  which  has  for 
its  object  the  structure  of  Uving  beings. 

Living  beings  are  divided  into  two  great  classes,  vegetables  and  animals ;  there  is, 
therefore,  a  vegetable  anatomy  and  an  animal  anatomy.  When  anatomy  embraces,  in  one 
general  view,  the  whole  series  of  animals,  comparing  the  same  organs  as  they  exist  in 
^he  different  species,  it  receives  the  name  of  zoological,  or  comparative  anatomy. 

Zoological  anatomy  is  denominated  philosophical  or  transcendental,  when  from  the  com- 
bination and  comparison  of  particular  facts  it  deduces  general  results,  and  laws  of  orga- 
nization. 

When  anatomy  is  confined  to  the  examination  of  one  species  only,  it  receives  the 
name  of  special ;  such  as  the  anatomy  of  man,  the  anatomy  of  the  horse,  &c.  Physio- 
logical anatomy  considers  the  organs  in  their  healthy  state.  Pathological  anatomy  regards 
them  as  altered  by  disease. 

\Vhen  physiological  anatomy  is  confined  to  the  examination  of  the  external  conforma- 
tion of  organs,  that  is  to  say,  of  aU  their  qualities  which  may  be  ascertained  without  di- 
vision of  their  substance,  it  is  called  descriptive  anatomy.  If,  on  the  contrary,  it  pene- 
trates into  the  interior  of  organs,  in  order  to  determine  their  constituent  or  elementary 
parts,  it  receives  the  name  general  anatomy,  or  of  the  anatomy  of  textures. 

Descriptive  anatomy  informs  us  of  the  names  of  organs  {anatomical  nomenclature), 
their  number,  situation,  direction,  size,  colour,  weight,  consistence,  figure,  and  relations  ; 
it  traces,  in  fact,  the  topography  of  the  hmnan  body.  In  more  than  one  respect,  it  is  to 
medicine  what  geography  is  to  history.  The  anatomy  used  by  painters  and  sculptors  may 
be  regarded  as  one  of  its  dependances,  and  may  be  defined  to  be  the  knowledge  of  the 
external  surface  of  the  body,  in  the  different  attitudes  of  repose,  and  in  its  various  move- 
ments. On  this  subject  it  may  be  observed,  that  the  precise  determination  of  the  ex- 
ternal eminences  and  depressions  may  afford  most  important  indications  regarding  the 
situation  and  state  of  deeply-seated  parts,  and  is  therefore  worthy  the  attention  of  the 
physician. 

Descriptive  anatomy,  in  the  sense  here  meant,  has  arrived  at  a  high  degree  of  perfec- 
tion. It  is  to  this  branch  that  reference  is  made  by  those  who  affirm  that  nothing  now 
remains  to  be  done  in  anatomy.  But  although  descriptive  anatomy  may  be  all  that  the 
surgeon  requires  to  enable  him  to  comprehend  the  lesions  which  most  commonly  fall 
under  his  notice,  and  to  perform  operations,  it  will  by  no  means  suffice  for  the  physician 
or  the  physiologist.  For  their  purposes,  anatomical  investigations  must  not  be  confined 
to  the  surface,  but  penetrate  into,  and  analyze  the  substance  of  organs.  Now  such  is 
the  object  of  general  or  textural  anatomy.  By  its  means  the  different  organs  are  re- 
solved into  their  component  tissues  :  these  tissues,  again,  are  reduced  to  their  simple 
elements,  which  are  then  studied  by  themselves,  independently  of  the  organs  which  they 
form ;  and  subsequently,  by  considering  the  elementary  constituents  as  combined  in  va- 
rious proportions,  the  organization  of  even  the  most  comphcated  and  dissimilar  parts  is 
made  manifest. 

There  is  one  species  of  anatomy  which  has  of  late  been  cultivated  with  the  greatest 
success.     I  mean  the  anatomy  of  the  fatus. 

The  anatomy  of  the  fatus,  or  the  anatomy  of  the  body  at  different  periods  of  life,  naiMcd 
the  anatomy  of  evolution,  has  for  its  object  the  study  of  the  development  of  organs,  their 
successive  modifications,  and  sometimes  even  the  metamorphoses  which  they  undergo, 
from  the  time  of  their  first  appearance  until  they  arrive  at  perfection. 

Lastly,  there  is  a  species  of  anatomy  to  which  the  term  of  "  applied  anatomy'''  may  be 
given,  because  it  comprehends  all  the  practical  applications  of  the  science  to  medicine 

*  The  word  Anatomy  is  derived  from  the  Greek  [ava,  up,  and  rtuvai,  I  cut).  It  is,  in  fact,  by  means  of 
dissection  principally  that  we  are  enabled  to  separate  and  study  the  different  organs.  But  injections,  desicca- 
tion, the  action  of  alcohol,  concentrated  acids,  &c.,  are  also  means  employed  by  the  anatomist 

A 


2  INTRODUCTION. 

and  surgery.  With  this  view,  the  body  is  divided  into  regions  or  departments,  and  each 
region  into  successive  layers.  The  relation  of  the  different  layers  is  pointed  out,  and 
in  each  layer  the  parts  Avhich  compose  it.  In  a  word,  the  constant  object  is  the  solution 
of  the  following  question  :  A  region,  or  any  part  of  the  surface  of  the  body  being  given, 
to  determine  the  subjacent  parts  which  correspond  to  it  at  different  depths,  and  their 
order  of  superposition.  This  has  generally  been  denominated  the  anatomy  of  regions, 
topographical  or  surgical  anatomy,  because  it  has  hitherto  been  studied  only  with  refer- 
ence to  its  uses  in  surgery.  It  may  easily  be  shown,  however,  that  with  the  exception  of 
the  limbs  or  extremities,  the  anatomical  knowledge  of  which  has  few  applications  to 
medicine,  properly  so  called,  the  study  of  regions  is  no  less  important  to  the  physician 
than  to  the  surgeon.  To  give  it,  therefore,  a  name  corresponding  with  its  use,  it  should 
be  called  medico-chirurgical  topographical  anatomy. 

Such  are  the  different  aspects  under  which  anatomy  may  be  regarded.  The  following 
work  is  essentially  devoted  to  descriptive  anatomy.* 

General  View  of  the  Human  Body. 

Before  entering  on  a  detailed  description  of  the  munerous  organs  which  enter  into  the 
composition  of  the  human  body,  it  is  advisable  to  present  a  rapid  sketch  of  the  whole. 
Such  general  views,  instead  of  embarrassing  the  mind,  at  once  enlighten  and  satisfy  it, 
by  exhibiting  the  objects  of  its  research  in  their  true  relations,  and  showing  the  end  to 
be  attained. 

There  is  one  general  covering,  which,  like  a  garment,  envelops  the  whole  body,  and 
is  moulded,  at  it  were,  round  all  its  parts.  This  covering  is  the  skin,  of  which  the  nails 
and  hair  are  dependances.  The  skin  presents  a  certain  number  of  apertures,  by  means 
of  which  a  communication  is  established  between  the  exterior  and  the  interior  of  the  body. 
These  apertures,  however,  are  not  formed  by  a  mere  perforation  or  breach  of  continuity 
in  the  skin ;  on  the  contrary,  this  membrane  passes  inward  at  the  circumference  of 
these  openings,  and  having  undergone  certain  important  modifications  in  its  structure, 
forms  the  mucous  membranes,  a  kind  of  internal  tegument,  which  may  be  considered  as 
a  prolongation  of  the  external  envelope.  We  might,  therefore,  strictly  speaking,  regard 
the  human  body  as  essentially  composed  of  a  skin  folded  back  upon  itself  This  idea  is, 
indeed,  realized  in  some  of  the  inferior  animals,  which  consist  of  a  mere  tube  or  canal. 
In  proportion,  however,  as  we  ascend  in  the  scale,  we  find  the  layers  which  separate 
these  two  teguments  become  more  and  more  increased  in  thickness,  and  cavities  are  at 
length  formed  between  them.  Nevertheless,  however  widely  these  membranes  may  be 
separated  from  each  other,  and  however  different  they  may  be  in  external  aspect,  there 
are  abundant  analogies  to  establish  unequivocally  their  common  origin. 

Under  the  skin  there  is  a  layer  of  adipose  cellular  tissue,  which  gently  elevates  it,  fiUa 
up  the  depressions,  and  contributes  to  impart  that  roundness  of  form  which  character- 
izes all  animals,  and  particularly  the  human  species.  In  some  parts,  there  are  muscles 
inserted  into  the  skin,  which  are  intended  for  its  movement ;  these  are  the  cutaneoua 
muscles.  In  man  they  are  very  inconsiderable,  and  are  confined  to  the  neck  and  face, 
where  they  play  an  important  part  in  giving  expression  to  the  physiognomy ;  but  in  the 
larger  animals  they  line  the  whole  skin,  and  in  certain  classes,  of  very  simple  organiza- 
tion, they  constitute  the  entire  locomotive  apparatus. 

The  superficial  veins  and  lymphatics  traverse  the  subcutaneous  cellular  tissue  :  tlie 
latter,  at  various  parts  of  their  course,  pass  through  enlargements  denominated  lymphatic 
ganglions,  or  lymphatic  glands,  which  are  grouped  together  in  certain  regions. 

Below  the  cellular  tissue  are  the  muscles,  red,  fleshy  bundles,  arranged  in  many  layers. 

In  the  centre  of  all  these  structures  are  placed  the  bones,  inflexible  columns,  v/hich 
serve  for  a  support  to  all  that  surrounds  them.  The  vessels  and  the  nerves  are  in  the 
immediate  neighbourhood  of  the  bones,  and,  consequently,  removed  as  much  as  possible 
from  external  injury.  Lastly,  around  the  muscles  and  under  the  subcutaneous  adipose 
tissue  are  certain  strong  membranes,  which  bind  the  parts  together,  and  which,  by  pro 
longations  detached  from  their  internal  surface,  separate  and  retain  in  their  situation 
the  different  muscular  layers,  frequently  each  particular  muscle :  these  envelopes  are 
the  aponeuroses. 

Such  is  the  general  structure  of  the  limbs  or  extremities. 

If  next  we  examine  the  trunk,  we  find  in  its  parietes  a  similar  structure,  but  more  in 
ternally  are  cavities  lined  by  thin  transparent  membranes,  named  serous,  on  account  of 
a  liquid  or  serosity  with  which  they  are  moistened.  In  these  cavities  are  situated  or- 
gans of  a  complex  structure,  called  viscera,  of  which  we  shall  give  a  rapid  enumeration 
m  an  order  conformable  to  the  offices  they  perform  in  the  animal  economy. 

The  hmnan  body,  as  well  as  that  of  other  organized  beings,  is  composed  of  certain 
parts,  denominated  organs  {bpyavov,  an  instrument),  which  differ  from  each  other  in 

*  Descriptive  anatomy  ought,  in  strictness,  to  be  confined  to  the  consideration  of  the  external  characters  ol 
organs,  or  what  is  understood  by  the  term  external  conformation  ;  nevertheless,  in  order  to  present  a  complete 
view  of  each  organ,  after  having  described  its  exterior,  we  shall  give  a  short  account  of  its  texture  and  deveJ- 
onment. 


GENERAL    VIEV^'6'p¥kte'  HUMAN    BODY.  3 

their  structure  and  use,  but  are  all  combined,  for  the  double  purpose  of  the  preservation 
of  the  individual,  and  the  continuance  of  the  species. 

To  accomplish  these  purposes,  the  organs  are  distributed  in  a  certain  number  of 
groups  or  series,  each  of  which  has  a  definite  end  to  fulfil.  This  end  is  denominated  a 
function :  the  series  of  organs  receives  the  name  of  an  apparatus.  Of  those  necessary 
for  the  preservation  of  the  individual,  some  are  designed  to  place  him  in  relation  with 
external  objects,  and  these  constitute  the  apparatus  of  relation :  the  others  are  destined 
to  repair  the  loss  which  the  parts  of  the  body  are  constantly  suffering  ;  they  form  the 
apparatus  of  nutrition. 

The  apparatus  of  relation  may  be  subdivided  into  two  classes  :  1.  The  apparaius  of 
sensation.     2.  The  apparatus  of  motion. 

Apparatus  of  Sensation. — The  apparatus  of  sensation  consists,  1.  Of  the  organs  of 
sense ;  2.  Of  the  nerves ;  3.  Of  the  brain  and  spinal  cord. 

The  organs  of  the  senses  are,  1.  The  skin,  which  possesses  sensibility,  the  exercise 
of  which  constitutes  tact.  The  skin  being  placed  under  the  direction  of  the  will,  and 
rendered  mobile  in  consequence  of  the  peculiar  mechanism  of  the  human  hand,  is  called 
the  organ  of  touch.  2.  The  organ  of  taste,  the  seat  of  which  is  in  the  cavity  of  the 
mouth,  that  is,  at  the  entrance  of  the  digestive  canal.  3.  The  organ  of  smell,  placed  in 
the  nasal  fossee,  the  commencement  of  the  respiratory  passages,  by  which  we  are  en- 
abled to  recognise  the  odorous  emanations  of  bodies.  4.  The  organ  of  hearing,  con- 
structed in  accordance  with  the  principles  of  acoustics,  and  placed  in  relation  with  the 
vibrations  of  the  air.  5.  TTie  organ  of  sight,  which  bears  relation  to  the  hght,  and  ex- 
hibits a  construction  in  harmony  with  the  most  important  laws  of  dioptrics. 

The  organs  of  sense  receive  impressions  from  without.  Four  of  them  occupy  the 
face,  and  are,  therefore,  placed  in  the  vicinity  of  the  brain,  to  which  they  transmit  im- 
pressions with  great  rapidity  and  precision  ;  and  that  organ  seems,  in  its  turn,  to  extend 
into  them,  so  to  speak,  by  means  of  the  nerves.  Indeed,  the  impressions  received  by 
the  external  organs  would  be  arrested  in  them,  were  it  not  for  certain  conductors  of 
such  impressions  :  these  conductors  are  the  nerves — white,  fasciculated  cords,  one  ex- 
tremity of  which  passes  into  the  organs,  while  the  other  is  connected  to  the  spinal  mar- 
row and  the  brain,  which  are  the  central  parts  of  the  nervous  system,  the  nerves  con- 
stituting the  peripheral  part. 

Apparatus  of  Locomotion. — The  apparatus  of  locomotion  consists,  1.  Of  an  active  or 
contractile  portion,  the  muscles.  These  are  terminated  by  tendons,  organs  of  a  pearly 
white  colour,  which  direct  upon  a  single  point  the  action  of  many  forces  ;  2.  Of  a  pas- 
sive portion,  the  bones,  true  levers,  which  constitute  the  framework  of  the  body,  and  tlie 
extremities  of  which,  by  their  mutual  contact,  form  the  articulations :  in  the  latter  we 
perceive  (a)  the  cartilages,  compressible,  elastic  substances,  which  deaden  the  violence 
of  shocks,  and  render  the  contact  uniform  ;  (jb)  an  unctuous  liquid,  the  synovia,  secreted 
by  membranes  denominated  synovial :  this  liquid  performs  the  office  of  the  grease  em- 
ployed in  the  wheel- work  of  machinery ;  (c)  bands  or  ligaments,  which  maintain  the  con- 
nexion of  the  bones. 

Such  is  the  apparatus  designed  to  establish  the  relation  between  man  and  external 
objects. 

Apparatus  of  Nutrition. — The  apparatus  which  performs  in  the  human  body  the  im- 
portant office  of  nutrition  consists  of  the  following  parts  : 

A.  The  digestive  apparatus,  which  consists  essentially  of  a  continuous  tube  or  canal, 
denominated  the  alimentary  canal.  This  canal  has  not  the  same  form  and  structure 
throughout  the  whole  extent :  on  the  contrary,  it  is  composed  of  a  series  of  vei7  dissim- 
ilar organs,  all,  however,  contributing  to  the  formation  of  one  common  passage.  These 
organs  are,  1.  The  mouth;  2.  The  pharynx;  3.  The  msophagus,  or  gullet;  4.  The  stom- 
ach ;  5.  The  intestines ;  which  are  farther  subdivided  into  the  small  intestines,  consisting 
of  the  duodenum,  jejunum,  and  ileum,  and  the  large  intestines,  comprising  the  cacum,  colon, 
and  rectum. 

To  this  long  tube,  the  greater  part  of  which  is  contained  in  the  abdomen,  where  it 
forms  numerous  reduplications,  are  annexed,  1.  The  liver,  a  glandular  organ,  whose 
office  it  is  to  secrete  the  bile,  and  which  occupies  the  superior  and  right  portion  of  the 
abdomen ;  2.  The  spleen,  whose  functions  are  involved  in  great  obscurity,  but  which 
may,  perhaps,  be  termed  an  appendix  to  the  liver,  on  the  left  side  ;  3.  The  pancreas,  which 
pours  a  fluid  into  the  duodemmi,  by  an  orifice  common  to  it  and  the  biliary  duct. 

B.  On  the  internal  surface  of  the  digestive  canal,  and  particularly  that  portion  of  it 
which  bears  the  name  of  the  small  intestine,  certain  vessels  open  by  numerous  orifices 
or  mouths,*  and  carry  otfthe  nutritive  fluids  prepared  by  the  process  of  digestion  :  these 
are  the  chyliferous  or  absorbent  vessels,  which  are  also  called  lacteal  vessels,  on  account  of 
the  white,  milky  aspect  presented  by  their  contents  while  absorption  is  going  on.  The 
absorbent  appai'atus  consists,  also,  of  another  set  of  vessels  denominated  lymphatics,  be- 
cause they  contain  a  colourless  liquid  named  lymph,  which  they  collect  from  a,H  parts  ol 

*  (This  must  not  be  understood  literally.     See  account  of  the  lacteals,  infni.l 


4  INTRODUCTION. 

the  body.  All  the  absorbent  vessels,  of  whatever  order  they  may  be,  traverse  at  differ^ 
ent  parts  of  their  course  certain  grayish  bodies,  called  lymphatic  gangUmis  or  glands,  and 
finally  terminate  in  the  venous  system. 

C.  The  venous  system  arises  from  all  parts  of  the  body :  it  takes  up,  on  the  one  hand, 
all  those  matters  which,  having  been  employed  a  sufficient  time  as  part  of  the  body,  must 
be  eliminated  from  it ;  and,  on  the  other  hand,  all  those  substances  which  are  carried  into 
the  system,  to  contribute  to  its  reparation  :  it  is  composed  of  vessels  denominated  veins 
which  at  various  distances  are  provided  with  valves,  and  at  last  unite  in  forming  two 
large  veins  called  vena  cavce,  of  which  one,  the  superior,  receives  the  blood  from  the  upper 
part  of  the  body ;  the  other,  the  inferior,  brings  back  that  which  has  circulated  in  the 
lower  portion. 

These  two  venae  cavae  terminate  in  the  central  organ  of  the  circalation,  the  heart,  a 
hollow  muscle,  containing  four  contractile  cavities  :  two  on  the  right  side,  the  right  au- 
ricle and  ventricle,  and  two  on  the  left,  the  left  auricle  and  ventricle. 

D.  Next  to  these  in  order  of  function  is  the  respiratory  apparatus,  composed  of  two 
spongy  sacs,  placed  on  each  side  of  the  heart,  and  occupying  almost  the  whole  of  the 
chest :  these  are  the  lungs.  They  receive  the  air  from  a  common  tube,  the  trachea, 
which  is  surmounted  by  a  vibratile  organ,  the  larynx,  which  opens  externally  by  the  nose 
and  mouth,  and  constitutes  the  organ  of  voice. 

E.  From  that  cavity  of  the  heart  which  is  called  the  left  ventricle,  arises  a  large  ves- 
sel, the  aorta :  this  forms  the  principal  and  primitive  trunk  of  the  whole  class  of  vessels 
named  arteries,  whose  office  it  is  to  convey  red  blood  to  all  parts  of  the  body,  to  main- 
tain their  heat  and  life. 

F.  There  still  remains  one  other  portion  of  the  nutritive  system,  the  urinary  appara- 
tus, consisting  of,  1.  The  kidneys,  organs  which  secrete  the  urine :  2.  The  ureters,  by 
means  of  which  the  urine,  as  soon  as  secreted,  passes  off  into  a  spacious  receptacle,  the 
bladder,  from  whence  it  is  at  intervals  expelled  along  a  passage  which  has  received  the 
name  of  urethra. 

Apparatus  of  Reproduction. — ^The  apparatus  above  mentioned  is  destined  for  individual 
preservation :  the  organs  which  secure  the  continuance  of  the  species  constitute  the 
generative  or  reproductive  apparatus.     They  differ  in  the  male  and  in  the  female. 

In  the  male  they  are,  1 .  The  testicles,  which  prepare  the  spermatic  or  fecundating  fluid , 
2.  The  vasa  deferentia,  tubes  which  transmit  this  fluid  from  the  testicle  where  it  is  se- 
creted to  the  vesiculse  seminales  ;  3.  The  vesicula.  seminales,  or  receptacles  of  semen  ; 
4.  The  cjaculatory  ducts,  through  which  the  semmal  fluid  passes  into  the  urethra ;  5.  The 
prostate  and  Cowpefs  glands,  glandular  appendages  of  the  organs  for  the  transmission 
of  the  semen ;  6.  The  penis,  by  means  of  which  the  fecundating  fluid  is  conveyed  into 
the  interior  of  the  genital  organs  of  the  female. 

The  generative  apparatus  in  the  female  is  composed  of  the  following  organs  :  1.  The 
ovaries,  the  function  of  which  is  to  produce,  or  keep  in  readiness,  the  ovulum  or  germ ; 
2.  The  uterine  tubes,  which  transmit  the  germ,  when  fecundated,  to  the  uterus ;  3.  The 
uterus  or  womb,  in  which  the  product  of  conception  remains  and  is  developed  during  the 
period  of  gestation ;  4.  The  vagina,  a  canal  which  permits  the  passage  of  the  foetus  at  its 
final  expulsion ;  5.  As  appertaining  to  the  system  should  be  mentioned  the  mammary 
glands,  which  secrete  the  milk  destined  for  the  nourishment  of  the  new-bom  infant. 

Genkral  Plan  of  the  Work. 

There  are  two  methods  by  which  the  numerous  facts  that  come  within  the  range  of 
anatomy  may  be  explained.  The  different  organs  may  be  studied  in  their  order  of  super- 
position, or  in  the  topographic  order,  a  capite  ad  calcem ;  in  this  way  the  most  dissimilar 
parts  are  brought  together,  while  others  are  separated  which  have  the  greatest  analogy ; 
or  they  may  be  considered  in  a  physiological  order,  i.  e.,  an  order  founded  upon  the  same 
grounds  as  serve  for  the  classification  of  functions.  This  is  clearly  the  most  rational, 
because  it  has  the  incontestable  advantage  of  preparing  for  the  study  of  the  functions  by 
that  of  the  organs.  It  may  be  easily  seen,  however,  that  this  physiological  arrangement 
should  be  modified  according  to  the  relative  difficulty  in  the  study  of  the  different  parts 
of  the  body  ;  for  the  great  aim  in  a  work  of  instruction  should  be  to  conduct  the  mind,  by 
degrees,  from  simple  and  easy  objects  to  those  which  are  more  complicated.  It  is  for 
this  reason  that  the  consideration  of  the  nervous  system,  which,  in  strict  accordance 
with  physiological  arrangement,  should  be  placed  near  to  that  of  the  locomotive  appara- 
tus, is  deferred.  The  object  proposed  has  been  to  adopt  an  arrangement  which  would, 
as  far  as  possible,  reconcile  both  these  views,  and,  at  the  same  time,  be  compatible  with 
the  greatest  economy  of  subjects  for  dissection ;  and  this  appears  to  be  secured  by  the 
method  generally  adopted,  at  least  with  a  few  slight  modifications. 

The  following  table  presents  a  view  of  the  general  plan  of  this  work : 

f  1 .  Of  the  bones— Osteology. 

,     •  .         , ,  ^  1  2.  Of  the  articulations — SyndeHHology. 

1.  Apparatus  of  locomotion S  3.  Of  the  muscles-Myology. 

14.  Of  the  aponeuroses — Aponeurolog  . 


GENERAL    OBSERVATIONS. 

B.  Apparatus  of  digestion,  apparams  of  respiration,      )  Splanchnoloffv 
genito-urinary  apparatus         ....)' 

f  Heart  T 

3.  Apparatus  of  the  circulation      ....     'S  Veins'*^     [  >Angeiology. 

I  Lymphatics  J 

f  Organs  of  the  senses'! 

4,  Apparatus  of  sensation  and  innervation     .       ,     <  jj^^^  ""'^         '        '  >  Neurology. 

LNerves      .        .        .J 


APPARATUS   OF  LOCOMOTION. 

OSTEOLOGY. 

OF    THE    BONES    IN    GENER.4.L. 

The  Bones  —  Importance  of  their  Study. — General  View  of  the  Skeleton. — Number  of  the 
Bones. — Method  of  Description. — Nomenclature. — Situation  in  general. — Direction. — Size, 
Weight,  and  Density  of  Bones. — Figure. — Distinction  into  Long,  Broad,  and  Flat  Banes. 
— Regions  of  Bones. — Eminences  and  Cavities. — Internal  Cofiformation. — Texture. — De- 
velopment of  Osteogeny. — Nutrition. 

The  bones  are  parts  of  a  stony  hardness,  but  yet  organized  and  living.  They  serve 
as  a  support  to  all  other  parts  of  the  body,  are  a  means  of  protection  to  many,  and  aiford 
points  of  attachment  to  the  muscles,  in  the  midst  of  which  they  are  situated.  All  the 
hard  parts  of  the  body,  however,  are  not  bones.  The  fundamental  character  of  a  bone 
consists  in  its  being  at  once  hard  and  organized.  As  the  bones  receive  vessels  for  the 
purpose  of  nutrition  at  every  part  of  their  surface,  they  are  surrounded  on  all  sides  by  a 
membrane  which  is  fibrous  and  vascular,  named  the  Periosteum  (nepl,  around ;  dareov, 
a  bone). 

According  to  this  definition,  the  teeth,  horns,  nails,  and,  in  articulated  animals,  the  ex- 
terior skeleton,  are  not  to  be  considered  as  bones,  but  merely  ossiform  concretions.  We 
may  add,  that  true  bones  belong  exclusively  to  vertebrated  animals. 

The  study  of  the  bones  constitutes  Osteology,  which  may  be  regarded  as  the  basis  of 
anatomy,  for  without  a  knowledge  of  the  bones  it  is  impossible  to  become  acquainted 
with  the  muscular  insertions,  or  the  exact  relations  between  the  muscles,  nerves,  vis- 
cera, and,  above  all,  the  vessels,  for  which  the  bones  afford  the  anatomist  invariable 
points  of  reference.  Osteology  has,  therefore,  ever  since  the  time  of  the  Alexandrian 
school,  formed  the  commencement  of  the  study  of  anatomy. 

In  the  present  day,  the  transcendental  anatomists  have  particularly  engaged  in  the 
study  of  the  osseous  system,  doubtless  on  account  of  the  facility  with  which  it  may  be 
investigated ;  and  from  their  labours,  though  in  many  respects  speculative,  a  more  ac- 
curate knowledge  has  been  obtained  of  some  of  the  nicer  points  of  osteology,  which  had 
scarce  attracted  notice  from  the  older  anatomists. 

Lastly,  from  the  admirable  researches  of  Cuvier  respecting  fossil  animals,  osteology 
has  become  one  of  the  most  important  bases  of  comparative  anatomy  and  geology.  By 
the  study  of  bones  the  anatomist  has  been  enabled  to  determine  genera  and  species,  no 
longer  existing  on  the  face  of  the  globe,  and  to  give,  as  it  were,  new  life  to  these  old  and 
disjointed  relics  of  the  antediluvian  animal  kingdom.  Thus  the  fossil  bones,  deposited 
in  an  invariable  order  of  superposition  in  the  crust  of  the  earth,  have  been  transformed 
into  monuments  more  authentic  than  historical  records. 

General  View  of  the  Skeleton. — ^The  bones  form  a  system  or  whole,  of  which  the  different 
parts  are  contiguous,  and  united  to  each  other.  The  only  exception  to  this  rule  is  the 
OS  hyoides,  and  yet  the  ligaments  by  which  it  is  connected  with  the  rest  of  the  system 
are  evidently  the  representatives  of  the  osseous  pieces,  which  in  the  lower  animals  con- 
nect this  bone  with  the  temporal. 

The  assemblage  of  the  bones  constitutes  the  skeleton.  It  is  called  a  natural  skeleton 
when  its  different  parts  are  connected  by  their  own  ligaments  ;  an  artificial  skeleton,  on 
the  other  hand,  is  one  of  which  the  bones  are  joined  together  by  artificial  connexions, 
such  as  metallic  wires,  &c. 

The  result  of  this  union  is  a  symmetrical  and  regular  structure,  essentially  composed 
of  a  central  column,  denominated  the  vertebral  column  or  spine,  which  terminates  superi- 
orly in  a  considerable  enlargement,  the  cranium,  and  inferiorly  in  certain  immovably 
united  vertebrae,  which  constitute  the  sacrum  and  coccyx.  To  this  column  the  following 
appendages  are  attached  :  1.  In  front  of  and  below  the  cranium,  a  complicated  osseous 
structure,  the  face,  divided  into  two  maxillce,  the  superior  and  inferior.  2.  On  each  side 
twelve  bony  arches,  flexible,  elastic,  and  curved — the  ribs,  which  are  united  in  front  to 
another  column,  the  sternum.  These  parts,  taken  together,  form  the  thorax.  3.  Four 
prolongations,  called  limbs  or  extremities :  two  superior,  or  thoracic,  as  they  are  termed, 
because  they  correspond  with  the  chest  or  thorax  ;  and  two  inferior  or  pelvic,  so  named 


g  6  OSTEOLOGY. 

on  account  of  their  connexion  with  the  basin  or  pelvis,  but  better  uamed^  abdominal  a 
tremities.  The  thoracic  and  abdominal  extremities  are  evidently  modifications  of  the 
same  fundamental  type,  and  are  essentially  composed  of  the  same  number  of  analogous 
parts,  viz.  :  1.  An  osseous  girdle,  the  superior  constituted  by  the  bones  of  the  shoulder, 
the  inferior  by  the  pelvis.  2.  A  part  Avhich  may  be  in  some  measure  regarded  as  the 
body  of  the  limb,  viz.,  the  humerus,  in  the  thoracic  extremity,  the  femur  in  the  abdominal. 

3.  A  manubrium  or  handle,  to  use  an  expression  of  Galen,  above  the  forearm,  below 
the  leg.  4.  Lastly,  digitated  appendages  which  form  the  extremities,  properly  so  called, 
viz.,  the  hand  and  the /oof. 

Number  of  the  Bones. — Authors  do  not  agree  respecting  the  number  of  the  bones. 
Some,  for  instance,  describe  the  sphenoid  and  the  occipital  as  forming  only  one  bone, 
while  most  anatomists  consider  them  two  distinct  bones.  Some  admit  three  pieces  in 
the  sternum,  which  they  describe  separately.  Many,  after  the  example  of  the  older 
writers,  divide  the  haunch  into  three  distinct  bones — ^the  pubes,  the  ischium,  and  the 
ileum :  others  recognise  five  pelvic  or  sacral  vertebrae ;  three  or  five  parts  of  the  os 
hyoides  ;  and,  lastly,  the  ossa  sesamoidea  and  the  ossa  wormiana-  are  omitted  by  some, 
but  by  others  are  reckoned  in  the  enumeration  of  the  bones. 

The  ideas  of  certain  modem  authors  with  respect  to  the  development  of  the  bones,  in- 
stead of  dispelling  the  uncertainty  which  attaches  to  the  enumeration  of  the  parts  of  the 
skeleton,  have  tended  not  a  little  to  increase  the  confusion,  because  many  of  them  have 
made  no  distinction  between  bones,  properly  so  called,  and  pieces  of  ossification.  All 
doubt,  however,  in  this  respect  will  cease,  provided  we  consider  as  distinct  bones  only 
those  portions  of  the  skeleton  which  are  separable  at  the  time  of  complete  development. 

The  time  at  which  the  osseous  system  arrives  at  its  perfect  development  is  between 
the  twenty-fifth  and  thirtieth  year. 

According  to  these  views,  we  may  count  in  the  human  body  198  bones,  viz. : 

Vertebral  column,  including  the  sacrum  and  coccyx    ....  26 

Cranium 8 

Face 14 

Os  hyoides 1 

Thorax  (ribs,  sternum) 25 

Superior  extremities,  each  32,  viz.,  shoulder,  arm,  forearm,  and  hand  64 

Inferior  extremities,  each  30,  viz.,  pelvis,  thigh,  leg,  and  foot  .  60 

198 
This  enumeration  does  not  include  the  ossa  wormiana,  nor  the  ossa  sesamoidea,  among 
which  we  include  the  patella. 

Of  these  198  bones,  34  only  are  single  :  all  the  others  are  in  pairs,  which  reduces  the 
number  to  be  studied  to  116. 

Before  proceeding  to  examine  each  piece  of  the  skeleton  in  particular,  we  shall  state 
the  method  we  intend  to  pursue  in  the  description.  The  chief  points  embraced  by  de- 
tailed descriptions  of  a  bone  are,  1.  Its  name;  2.  Its  general  situation;  3.  Its  direction ; 

4.  Its  bulk  and  weight ;  5.  Its  figure ;  6.  Its  regions ;  7.  Its  relations ;  8.  Its  internal 
conformation  ;  9.  Its  intimate  texture  ;  10.  Its  development. 

Nomenclature. — Osteological  nomenclature  has  many  imperfections.  Persuaded  of 
the  importance  of  a  suitable  choice  of  language  in  the  study  of  all  the  sciences,  some 
anatomists  have  endeavoured  to  introduce  reforms,  but  with  little  success,  the  old  de- 
nominations being  still  for  the  most  part  retained.  From  these  modern  systems  of  no- 
menclature we  shall  adopt  only  such  terms  as  Eire  strikingly  appropriate,  or  such  as  have 
already  been  sanctioned  by  usage.  We  may  here  observe  that  the  denominations  of 
bones  have  been  derived,  1.  From  their  situation  ;  as  the  frontal,  which  is  so  called  be- 
cause it  is  situated  in  the  forehead :  2.  From  a  resemblance,  usually  very  obscure,  to  some 
well-known  object,  as  the  bones  named  tibia,  scaphoid,  malleus,  incus,  stapes ;  or  to  some 
geometrical  figure,  as  the  cuboid :  3.  From  their  size  ;  as  the  os  magnum  of  the  carpus, 
and  the  small  bones  or  ossicula  of  the  ear  :  4.  From  some  circumstance  of  their  external 
conformation  ;  as  the  cribriform  or  ethmoid  bone,  the  unciform  or  hooked  bone  :  5.  From 
the  name  of  the  author  who  first  most  carefully  described  them ;  as  the  ossicles  of  Ber 
tin,  of  Morgagni — swings  of  Jngrassias,  &c. 

General  Situation  of  Bones. — The  situation  of  a  bone  is  determined  by  comparing  the 
place  which  it  occupies  with  that  occupied  by  other  bones  of  the  skeleton.  In  order  to 
make  this  comparison,  the  skeleton  is  supposed  to  be  surrounded  by  certain  planes, 
which  are  thus  denominated :  1 .  A7i  anterior  plane,  passing  before  the  forehead,  the 
breast,  and  the  feet ;  2.  A  posterior  plane,  passing  behind  the  occiput  and  the  heels  ;  3.  A 
superior  plane,  placed  horizontally  above  the  head  ;  4.  An  inferior  plane,  which  passes  be- 
low the  soles  of  the  feet ;  5  and  6.  The  two  lateral  planes,  which  complete  the  sort  of 
case  or  parallelepiped  with  which  we  suppose  the  skeleton  to  be  surrounded.  Lastly, 
the  skeleton  being  symmetrical,  i.  e.,  exactly  divisible  into  two  similar  halves,  we  admit 
a  seventh  imaginary  plane,  the  median  or  antero-posterior,  separating  these  two  halves. 
By  the  term  median  line  is  understood  an  imaginary  line  traced  so  as  to  mark  exteriorly 
the  division  of  all  the  symmetrical  bone"  of  the  skeleton  into  two  similar  halves. 


GENEEAL   OBSERVATIONS.  7 

These  points  being  understood,  nothing  is  more  easy  than  to  determine  the  position 
of  a  bone.  If  it  approach  nearer  to  the  anterior  plane  than  others  with  which  it  is  com- 
pared, it  is  said  to  be  anterior  to  them ;  if  it  be  nearer  the  posterior  plane,  it  is  said  to  be 
posterior  to  them.  Let  us  take,  for  example,  the  malar  or  cheek  bones.  With  respect 
to  the  whole  face,  they  are  placed  at  the  anterior,  superior,  and  in  some  degree  the  lateral 
part;  relatively  to  the  neighbouring  bones,  they  are  situated,  1.  Below  the  frontal;  2. 
Above  and  a  little  external  to  the  maxillary ;  3.  Before  the  great  wings  of  the  sphenoid 
and  the  zygomatic  process  of  the  temporal. 

Direction  of  Bones. — The  direction  of  a  bone  is  absolute  or  relative.  The  absolute  di- 
rection is  expressed  by  the  terms  straight,  curved,  angular,  or  twisted ;  in  a  word,  it  is  the 
direction  of  a  bone  considered  by  itself,  or  independently  of  its  situation  in  the  skeleton. 
The  long  bones  are  never  quite  straight :  sometimes  they  present  a  shght  degree  of  cur- 
vature, as  the  femur ;  sometimes  their  extremities  are  curved  in  opposite  directions, 
like  the  letter  S,  as  the  clavicle :  sometimes,  again,  they  are  twisted  upon  their  own 
axes,  as  the  humerus,  the  fibula,  &c. 

The  relative  direction  is  determined  by  reference  to  .the  planes  which  circumscribe 
the  skeleton.  Viewed  in  this  manner,  a  bone  is  vertical,  horizontal,  or  oblique.  It  is 
needless  to  enter  into  any  explanation  of  the  terms  vertical  and  horizontal ;  but  with  re- 
gard to  the  oblique  direction,  it  may  be  stated  that  this  is  determined  by  the  respective 
situations  of  its  two  extremities.  For  example,  a  bone  is  oblique  when  one  extremity 
approximates  the  superior,  the  median,  and  the  posterior  planes,  while  the  other  ap- 
proaches nearer  to  the  inferior,  lateral,  and  anterior  planes  ;  such  a  bone  is  said  to  be 
obhque  from  above  downward,  from  within  outward,  and  from  behind  forward.  It  is  easy 
to  see  that  in  this  way  the  situation  of  a  bone  relatively  to  the  different  planes  may  be 
determined  with  the  greatest  exactness.  It  should  be  observed,  that  in  describing  the 
direction  of  a  bone,  we  should  always  set  out  from  the  same  point.  Thus,  if  the  direc- 
tion of  a  bone  from  above  downward  is  spoken  of  in  determining  its  obhquity  from  be- 
fore backward,  and  from  vrithin  outward,  we  should  always  commence  with  the  supe 
rior  extremity. 
\^  Size,  Weight,  and  Density  of  Bones. — The  size  of  a  bone  may  be  measured  by  the  ex- 
/*  tent  of  its  three  dimensions  ;  but  as  an  exact  estimate  is  not  in  general  required,  it  is 
sufficient  to  indicate  the  voliftne  of  each  bone  relatively  to  others,  whence  has  arisen 
the  division  of  bones  into  great,  middle-sized,  and  small ;  a  distinction,  however,  altogeth- 
er vague  and  futile,  since  from  the  largest  to  the  smallest  bones  there  is  so  regular  a 
gradation  that  the  limits  assigned  must  be  quite  arbitrary. 

The  weight,  or  the  mass  of  the  skeleton  compared  with  the  rest  of  the  body,  the  weight 
of  each  bone,  and  the  comparative  weight  of  different  bones,  are  points  of  little  inter- 
est ;  such,  however,  is  not  the  case  with  the  specific  weight  or  density  of  bones. 

In  respect  of  density,  viz.,  the  number  of  molecules  in  a  given  volume,  the  bones  are 
the  heaviest  of  all  organs.  The  truth  of  this  assertion  is  by  no  means  contradicted  by 
the  lightness  of  certain  bones,  which  is  only  apparent,  and  which  is  caused  by  vacant 
spaces  or  cells  in  their  substance.  This  density  varies  in  different  kinds  of  bones,  in 
bones  of  the  same  kind,  and  even  in  different  parts  of  the  same  bone.  Thus,  in  the  long 
bones,  the  greatest  density  is  in  the  middle  :  the  extremities  of  the  long  bones  and  the 
short  bones  have  a  much  lower  density.  The  broad  or  flat  bones  hold  a  middle  place 
between  the  shaft  of  long  bones  and  the  short  bones.  Of  these  broad  bones,  those  of  the 
cranium  are  heavier  than  those  of  the  pelvis.  Age  has  a  remarkable  influence  upon  the 
specific  weight  of  bones.  It  has  been  said  that  the  bones  of  the  aged  are  specificcdly 
more  heavy  than  those  of  the  adult,  just  as  the  bones  of  the  adult  are  specifically  heavi- 
er than  those  of  the  infant ;  and  this  assertion  appears  the  more  probable,  from  it  being 
generally  admitted,  as  a  law  of  organization,  that  the  phosphate  of  lime  increases  in 
bones  with  the  progress  of  age  ;  and  it  is  well  known  that  the  weight  of  bones  depends, 
in  part,  on  the  presence  of  this  calcareous  phosphate.  But  on  this  point,  as  on  many 
others,  experience  has  refuted  these  preconceived  opinions.  Thus,  it  is  certain  that  the 
specific,  as  well  as  the  absolute  weight  of  bones,  is  much  less  considerable  in  the  old 
person  than  in  the  adult ;  and  this  difference  depends  upon  the  loss  of  substance  which 
the  bones  undergo,  in  common  with  all  other  tissues,  during  the  progress  of  age  :  thus, 
in  aged  subjects,  the  walls  of  the  cylinder  of  the  long  bones  are  remarkably  diminished 
in  thickness,  while  the  medullary  cavity  is  proportionally  increased.  We  rnay  even  af- 
firm, with  Chaussier,  that  the  medullary  cavity  of  the  shaft  of  long  bones  has  a  greater 
diameter,  in  proportion  as  the  individual  is  advanced  in  age.  In  like  manner,  the  cells 
of  the  spongy  tissue  become  much  larger,  and  their  w-alls  acquire  an  extreme  tenuity. 
It  may,  nevertheless,  be  contended,  that  the  weight  of  the  osseous  fibre,  or,  rather,  of 
the  osseous  molecules  of  the  old  people,  is  gieater,  comparatively,  than  that  of  the  same 
parts  in  the  adult ;  and  this  presumption  is  ahnost  converted  into  certainty  by  chemical 
iinalysis,  which  shows  an  excess  of  phosphate  of  lime  in  the  bones  of  the  aged :  to  re- 
move all  doubts  upon  this  point,  it  would  he  necessary  to  grind  an  adult  bone  and  an  old 
one,  and  to  weigh  in  the  balance  an  equal  bulk  of  each  powder.  In  this  way  the  contra- 
dictory statements  of  certain  authors  might  be  reconciled. 


-K 


8  OSTEOLOGY. 

The  increasing  fragility  of  bones,  and  the  consequent  frequency  of  fractures  in  old  age, 
are  CEisily  explained,  since  along  with  the  accumulation  of  phosphate  of  lime,  which  di- 
minishes the  elasticity  while  it  increases  the  brittleness,  there  occurs  a  diminution  of 
bulk,  and,  consequently,  there  is  less  resistance.  It  is  with  respect  to  the  quantity  of 
calcareous  phosphate  alone  that  the  osseous  system  can  be  said  to  preponderate  in  old  age. 

Shape  of  Bones. — The  shape  of  a  bone  is  determined,  1.  By  comparison  either  with 
different  known  objects,  or  with  geometrical  figures :  thus  the  frontal  bone  has  been 
compared  to  the  scallop-shells  of  pilgrims,  the  sphenoid  to  a  bat  with  extended  wings, 
&c.  It  may  be  readily  conceived  that,  notwithstanding  its  want  of  exactness,  this  meth- 
od of  comparison,  so  familiar  to  the  ancients,  cannot  be  altogether  proscribed.  The 
comparison  of  bones  whose  forms  are  so  irregular  with  the  regular  solid  figures  of  which 
geometry  treats  is  no  less  inaccurate  than  the  preceding ;  nevertheless,  we  shall  con- 
tinue, like  other  anatomists,  to  speak  of  the  short  bones  as  cuboidal,  the  shafts  of  long 
bones  as  being  prismatic  and  triangular,  the  lower  maxdlaj  parabolic,  &c.  We  shall 
speak  of  spheres,  of  cones,  of  ovoids,  of  cylinders,  &c. 

2.  The  symmetry  or  want  of  synmietry  of  bones  is  a  fundamental  point  in  the  deter- 
mination of  their  figure  :  thus,  some  bones  are  divisible  into  two  halves  exactly  resem- 
bling each  other ;  these  are  the  syimnetrical  or  azygos  bones,  also  called  median,  be- 
cause they  always  occupy  the  middle  line.  The  others  can  not  be  divided  into  two  sim- 
ilar parts  :  these  are  the  asymmetrical  bones,  called  also  lateral  or  corresponding,  because 
they  are  always  in  pairs,  and  situated  on  opposite  sides  of  the  median  line. 

3.  The  figure  of  a  bone  comprehends,  also,  the  proportion  which  its  three  dimensions 
bear  to  each  other.  When  the  three  dimensions,  length,  breadth,  and  thickness,  are 
nearly  equal,  the  bone  is  said  to  be  short ;  when  the  length  and  breadth  are  almost  the 
same,  and  both  greater  than  the  thickness,  the  bone  is  called  broad  or  fiat.  Lastly,  the 
predominance  of  one  dimension  over  the  two  others  constitutes  the  character  of  long 
bones.  The  distinction  here  drawn,  however,  is  not  altogether  exact,  because  there  are 
certain  mixed  bones  which  partake  at  the  seime  time  of  the  character  of  the  long  and  the 
broad  bones. 

Some  general  observations  upon  the  three  great  classes  will  not  be  out  of  place  here, 
as  they  will  be  applicable  in  the  description  of  the  individual  bones. 

Ge?ieral  Characters  of  Long,  Flat,  and  Short  Bones. 

Of  Long  Bones. — The  long  bones  are  situated  in  the  extremities,  in  the  centre  of  which 
they  form  a  set  of  pillars  or  levers  placed  upon  each  other.  The  bones  of  the  abdominal 
extremities  are  generally  longer  and  larger  than  those  of  the  thoracic.  The  longest 
bones  are  in  the  upper  part  of  the  limbs  ;  it  may  be  said,  indeed,  that  the  length  of  bones 
is  in  the  direct  ratio  of  their  proximity  to  the  trunk.  The  diameter  of  the  long  bones  is 
smallest  in  their  middle.  From  this  part,  as  from  a  centre,  they  gradually  increase  in 
volume,  and  at  their  extremities  are  much  enlarged,  so  as  to  present  a  diameter  doubld 
or  treble  that  of  the  shaft.  Every  long  bone,  therefore,  presents  a  biconical  form,  i.  e., 
is  shaped  like  two  cones  united  by  their  summits. 

A  long  bone  consists  of  a  shaft  and  extremities.  The  shaft  of  the  long  bones  is  almost 
always  prismatic  and  triangular  ;  so  much  so,  that  in  this  respect  the  bones  seem  to  be 
an  exception  to  the  general  rule  of  organized  bodies,  which  have  usually  a  rounded  form, 
and  to  approach  nearer  that  of  the  mineral  kingdom,  the  characteristic  shape  of  which 
is  angular. 

The  extremities  of  long  bones  are  enlarged,  that  they  may  serve,  1.  For  articula- 
tions ;  2.  For  the  insertion  of  ligaments  and  muscles  ;  3.  For  the  reflection  of  tendons, 
the  direction  of  which  they  alter.  Each  extremity  presents  a  smooth  articular  surface, 
covered  with  cartilage  in  the  fresh  state,  and  not  perforated  by  any  foramina,  and  a 
non-articular  portion,  rough,  pierced  with  apertures,  and  covered  with  eminences  and 
depressions. 

Of  Broad  or  Flat  Bones. — These  bones,  intended  to  form  the  parietes  of  cavities,  are 
more  or  less  curved,  and  present  for  consideration  a  circumference  and  two  surfaces  ; 
the  internal  concave,  the  external  convex.  No  single  broad  bone  constitutes  a  cavity  ; 
there  are  always  a  certain  number  united  for  this  purpose.  Some  broad  bones  are  alter- 
nately concave  and  convex  on  the  same  surface,  as  the  haunch  bones.  In  flat  or  broad 
bones  there  is  no  accurate  correspondence  between  the  inequalities,  ridges,  or  depres- 
sions of  the  two  surfaces.  Thus,  the  iliac  portion  of  the  haunch  bones,  instead  of  pre 
senting  a  convexity  on  the  inner  surface,  to  correspond  with  the  external  iliac  fossa,  is 
hoUowed  out  into  another  depression,  the  internal  iliac  fossa.  In  like  manner,  in  the 
cranium  certain  impressions  and  eminences  exist  on  the  internal  surface,  whUe  the  ex- 
ternal is  uniformly  convex,  and  almost  smooth.  The  parietal,  and  even  the  occipital 
protuberances,  would  be  twice  or  three  times  more  prominent  if  the  interior  concavity 
were  faithfully  represented  by  a  corresponding  external  prominence,  and  if  this  concav- 
ity were  not  in  a  great  measure  hollowed  out  from  the  substance  of  the  bone. 

The  circumference  of  broad  bones  being  intended  either  for  articulations  or  for  inser- 
tions, is  for  this  purpose  greatly  thickened.     Thus  the  parietal  bones,  which  are  very 


GENERAL    OBSERVAT[ONS.  9 

thin  at  their  centre,  become  considerably  thicker  at  the  circumterence.  The  broad 
bones  present  at  their  circumference  sometimes  a  simple  enlargement,  when  it  is  in- 
tended for  muscular  insertions  only ;  for  example,  the  haunch  bones  :  sometimes  indent- 
ations of  various  kinds,  and  sinuosities,  when  it  is  to  serve  the  purpose  of  articulation ; 
for  instance,  the  bones  of  the  cranium. 

Of  Short  Bones. — These  are  principally  met  with  in  the  vertebral  column,  the  carpus, 
and  the  tarsus  ;  in  fact,  wherever  great  solidity  is  required  in  connexion  with  slight  mo- 
bility :  several  of  them  are  always  grouped  together ;  their  form  is  extremely  irregular, 
but  generally  cuboid  ;  they  have  also  numerous  facettes  for  articulation.  The  non-artic- 
ular portion  is  rough,  for  the  insertion  of  ligaments  and  tendons. 

Regions  of  Bones. — There  are  so  many  objects  to  be  considered  on  the  surface  of  a 
bone,  that  it  is  necessary,  in  order  to  prevent  the  omission  of  any  essential  detail  in 
the  description,  to  divide  the  surface  into  a  certain  number  of  parts  or  regions,  which 
should  be  successively  examined.  These  different  parts  or  regions  have  been  denom- 
inated faces,  borders,  and  angles.  Thus,  in  the  prismatic  and  triangular  shafts  of  long 
bones,  there  are  three  faces  and  three  borders  to  be  considered  ;  in  the  flat  bones,  two  faces 
and  a  circumference,  which  is  again  subdivided  into  borders  and  angles  formed  by  the  meet- 
ing of  these  borders.  There  are  six  faces  in  the  short  bones.  These  faces  and  borders  are 
named  sometimes,  from  their  situation,  superior,  inferior,  anterior,  posterior,  &c. ;  some- 
times from  the  parts  which  they  contribute  to  form,  such  as  the  orbital  and  palatine  fa- 
ces of  the  superior  maxillary  bone  ;  sometimes  from  their  relations  to  other  parts,  as 
the  cerebral  and  cutaneous  face  of  the  bones  of  the  cranium,  the  frontal,  occipital,  and  tem- 
poral borders  of  the  parietal  bones.  When  the  borders  give  insertion  to  a  great  number 
of  muscles,  it  has  been  deemed  advisable  to  divide  these  into  three  parts  or  parallel 
lines  :  the  middle  is  then  called  the  interstice,  and  the  two  lateral  are  named  lips,  the  in- 
ternal and  external  lip ;  the  superior  border  of  the  haunch  bone,  and  the  linea  aspera  of 
the  femur,  are  examples. 

Eminences  and  Cavities  of  Bones. — ^The  bones  present  certain  eminences  and  cavities, 
of  which  it  is  proper  to  take  a  general  survey  in  this  place. 

Eminences  of  Bones. — The  osseous  eminences  or  processes  were  divided  by  the  an- 
cients into  two  great  classes,  apophyses  and  epiphyses,  distinguished  by  the  difference 
of  their  mode  of  development.  According  to  their  view,  some  of  these  eminences  arise 
from  the  body  of  the  bone,  appearing  to  be  nothing  more  than  prolongations  or  vege- 
tations of  its  substance :  these  they  called  apophyses ;  others,  on  the  contrary,  are 
formed  by  separate  osseous  centres  or  nuclei,  which  make  their  appearance  at  various 
times  during  the  process  of  the  development  of  bone  :  to  these  they  gave  the  name  of 
epiphyses.  This  distinction,  however,  founded  upon  incomplete  observation,  has  been 
totally  rejected,  since  the  researches  of  M.  Serres  on  Osteogeny  have  rendered  it  evi- 
dent that  almost  aU  the  osseous  eminences  are  developed  from  isolated  nodules ;  so 
that  an  eminence,  which  at  one  time  is  an  epiphysis,  becomes  afterward  an  apophysis. 
If,  therefore,  the  majority  of  eminences  are  formed  from  separate  osseous  points,  the  dif- 
ference between  them  can  apply  only  to  the  relative  periods  at  which  they  become  uni- 
ted to  the  body  of  the  bone. 

A  far  more  important  distinction  is  that  by  which  the  eminences  are  divided  into 
articular  and  non-articular. 

The  articular  eminences  have  received  different  names.  1.  They  are  called  dentic- 
ulations  when  they  form  angular  eminences  resembling  the  teeth  of  a  saw ;  these  are 
best  seen  in  the  bones  of  the  cranium.  This  kind  of  eminence  is  employed  only  in  im- 
movable articulations. 

The  others  belong  to  joints  which  admit  of  motion,  and  have  received  the  folloMing 
names  :  1.  They  are  called  heads  when  they  represent  a  portion  of  a  sphere  supported 
by  a  more  contracted  portion,  to  which  the  name  of  neck  is  given  ;  for  example,  the  head 
and  neck  of  the  femur.  2.  The  term  condyle  is  applied  to  them  when  they  resemble  an 
elongated  head,  or  a  portion  of  an  ovoid  cut  parallel  to  its  greatest  diameter  ;  for  exsim- 
ple,  the  condyles  of  the  inferior  maxilla. 

The  non-articular  eminences  are,  for  the  most  part,  designed  for  muscular  insertions. 
Their  appellations  are  in  general  derived  from  their  shape.    Thus,  they  are  denominated, 

1 .  Prominences.  When  they  are  but  slightly  elevated,  smooth,  and  almost  equally  ex- 
tended in  all  directions  ;  as  the  parietal  and  frontal  eminences. 

2.  Mamillary  Processes.  When  they  resemble  papillas ;  for  instance,  the  mamillary 
processes  of  the  internal  surface  of  the  bones  of  the  cranium. 

3.  Tuberosities.  When  they  are  of  a  larger  size,  round,  but  uneven ;  for  example,  the 
occipital  protuberance,  the  bicipital  tuberosity  (or  tubercle)  of  the  radius. 

4.  Spines  or  Spinous  Processes.  When,  from  their  acuminated,  but  generaUy  rugged 
form,  they  bear  some  resemblance  to  a  thorn ;  as  the  spine  of  the  tibia,  the  spinous  pro- 
cesses of  the  vertebrae. 

5.  Lines.  When  their  length  greatly  exceeds  their  breadth  ;  as  the  semicircular  lines 
of  the  occipital  bone.  When  these  lines  are  more  prominent,  and  covered  with  asper- 
ities, they  receive  the  name  of  linear  asperae ;  as  the  hnea  aspera  of  the  femur. 

B 


10  OSTEOLOGY. 

6.  Crests.  When  they  are  elevated,  and  have  a  sharp  edge ;  as  the  external  and  inter 
nal  crest  of  the  occipital  bone,  the  crest  of  the  tibia.  One  of  these  eminences  has  been 
denominated  the  crista  galli,  because  it  bears  some  resemblance  to  the  comb  of  a  cock. 

7.  The  term  apophyses  (or  processes)  has  been  retained  for  those  eminences  which  are 
of  a  certain  size,  and  appear  to  form,  as  it  were,  a  little  bone  superadded  to  that  from 
which  they  spring ;  they  are  distinguished,  for  the  most  part,  by  epithets  derived  from 
their  shape.  Thus,  the  clinoid  processes  of  the  sphenoid  are  so  called  from  their  supposed 
resemblance  to  the  supporters  of  a  bed  {kMvjj,  a  bed  ;  ehhc,  shape).  Pterygoid  processes 
are  those  wliich  are  like  wings  (Trrcptf,  a  wing).  Mastoid,  such  as  resemble  a  nipple 
(fiaardc,  manrmia).  Zygomatic,  such  as  have  the  form  of  a  yoke  {Cvyoc,  a  yoke).  Styloid, 
such  as  are  like  a  style.  Coronoid,  such  as  are  shaped  like  one  of  the  angular  projec- 
tirns  of  a  diadem.*  Odontoid,  such  as  resemble  a  tooth  ;  as  the  odontoid  process  of  the 
second  cervical  vertebra.  Coracoid,  such  as  have  the  form  of  a  raven's  beak  («dpaf,  a 
raven) ;  as  the  coracoid  process  of  the  scapula.  Malleoli,  euch  as  are  like  a  hammer 
(malleus,  a  hammer). 

Some  processes  have  received  names,  1 .  From  the  parts  they  contribute  to  form — 
orbitar  processes,  malar  processes,  olecranon  {uTiivrj,  the  elbow  ;  Kpdvov,  head) :  2.  From 
their  direction  ;  as  the  ascending  process  of  the  superior  maxilla :  3.  From  their  uses  ; 
as  the  trochanters  (jpoxau,  to  turn),  because  they  serve  for  the  insertion  of  muscles, 
which  rotate  the  leg  on  its  own  axis. 

No  part  of  the  language  of  osteology,  perhaps,  is  more  faulty  than  the  nomenclature  of 
the  eminences.  Thus,  how  unlike  is  the  spine  of  the  scapula  to  the  spinous  processes 
of  the  vertebrae,  or  the  styloid  process  of  the  temporal  to  the  diminutive  projection  call- 
ed styloid  of  the  radius !  Many  eminences  which  perform  analogous  offices  have  re- 
ceived different  names  :  thus,  the  eminences  of  the  humerus,  which  give  attachment  to 
its  rotating  muscles,  are  called  the  great  and  small  tuberosities  ;  while  the  correspond- 
ing parts  of  the  femur  have  been  denominated  trochanters.  While,  therefore,  we  retain 
the  names  consecrated  by  usage,  we  shall  be  careful  to  point  out  the  more  rational  terms 
substituted  by  modern  anatomists,  and  particularly  by  Chaussier. 

The  size  of  the  eminences  of  insertion  is  in  general  proportional  to  the  number  and 
strength  of  the  muscles  and  ligaments  which  are  attached  to  them.  To  be  convinced 
of  this  fact,  it  is  only  necessary  to  compare  the  male  and  female  skeleton,  or  that  of  a 
man  of  sedentary  habits  and  that  of  a  person  devoted  to  athletic  exercises.  This  re- 
markable correspondence  between  the  size  of  osseous  eminences  and  the  strength  of  the 
muscles  which  are  inserted  into  them,  has  given  rise  to  the  opinion  that  these  eminences 
are  formed  by  muscular  traction.  It  is  easy  to  refute  this  notion,  and  without  entering 
into  details  which  belong  to  general  anatomy,  we  shall  prove,  by  facts,  that  the  osseous 
projections  enter  into  the  primordial  plan  of  organization,  so  much  so,  that  they  would 
have  doubtless  existed,  even  though  the  muscles  had  never  exercised  any  traction  upon 
the  bones.  I  have  twee  had  occasion  to  dissect  the  thoracic  extremities  of  individuals, 
who,  in  consequence  of  convulsions  during  their  earliest  infancy,  had  suffered  complete 
paralysis  of  these  parts.  The  limb  affected  had  scarcely  the  proportions  of  that  of  a 
child  of  eight  or  nine  years,  while  the  opposite  hmb  was  perfectly  developed.  Never- 
theless, in  this  atrophied  limb,  the  smallest  as  well  as  the  largest  projections  were  per- 
fectly marked.  Moreover,  very  powerful  muscles  are  often  inserted  into  cavities,  as, 
for  instance,  the  pterygoid  cavity  of  the  sphenoid. 

Cavities  of  Bones. — Besides  the  great  cavities  of  the  skeleton,  cavities  in  the  formation 
of  which  many  bones  concur,  and  which  are  destined  to  lodge  and  defend  the  organs 
most  important  to  Ufe,  there  are  a  great  number  of  smaller  excavations  formed  in  the 
substance  of  the  bone  itself. 

These  cavities,  like  the  eminences,  are  divided  into  two  great  classes,  articular  and 
non-articular.  The  articular  cavities  have  received  different  names.  1.  The  term  cotyloid 
designates  the  articular  cavity  in  the  haunch  bone,  because  it  is  deep  and  round,  like  a 
vessel  known  by  the  ancients  under  the  name  of  kotvIt].  2.  The  name  glenoid  (from 
y7ir)vr])  is  applied  to  many  articular  cavities,  which  are  more  shallow ;  for  example,  the 
glenoid  cavity  of  the  scapula,  the  glenoid  cavity  of  the  temporal  bone.  3.  The  term  al- 
veoli has  been  assigned  to  the  cells  or  sockets  in  which  the  roots  of  the  teeth  are  lodged. 
It  is  not  correct,  however,  to  consider  as  an  articulation  the  union  of  the  teeth  with  the 
jaws,  because,  as  we  shall  afterward  show,  the  teeth  are  not  true  bones. 

The  non-articular  cavities  are  to  be  considered  with  reference  both  to  their  figure  and 
their  uses.  From  their  figure,  they  have  received  the  following  denominations  :  1.  Fossa, 
or  pits,  are  cavities  largely  excavated,  wider  at  the  margin  than  at  the  bottom ;  e.  g.,  the 
parietal  fossaj.  2.  Sinuses  are  cavities  with  a  narrow  entrance  ;  as  the  sphenoidal  sinus, 
maxillary  sinus,  &c.  3.  The  term  cells  is  applied  when  the  cavities  are  small,  but  nu- 
merous, and  communicating  with  each  other ;  as  the  ethmoidal  cells,  &c.  4.  Channels 
{gutters)  are  cavities  which  resemble  an  open  semi-cyhndrical  canal ;  as  the  channels  for 
the  longitudinal  and  lateral  sinuses  of  the  scull.    5,  These  take  the  name  of  grooves 

*  [Also  from  Kopiivt],  a  wow — like  a  crow's  beak.] 


GENERAL   OBSERVATIONS.  11 

(coulisses)  when  they  are  lined  by  a  thin  layer  of  cartilage,  for  the  passage  of  tendons  ; 
as  the  bicipital  groove  of  the  humerus.  The  terra  pulley  or  trochlea  is  applied  to  grooves 
which  have  their  two  borders  also  covered  with  cartilage.  6.  Furrows  are  superficial 
impressions,  long,  but  very  narrow,  and  intended  for  the  lodgment  of  vessels  or  nerves, 
as  the  furrows  for  the  middle  meningeal  artery.  7.  When  more  deeply  excavated  than 
the  last,  and  angular  at  the  bottom,  they  are  named  by  the  Frencli  anatomists  Rainures. 
8.  A  notch  {incisura)  is  a  cavity  cut  in  the  edge  of  a  bone.* 

The  cavities  wliich  we  have  described  exist  only  on  one  surface  of  a  bone  ;  those  which 
perforate  its  substance  are  usually  denominated  foramina  or  holes. 

1.  When  a  foramen  has  an  irregular,  and,  as  it  were,  lacerated  orifice,  it  is  named  a 
foramen  lacerum.  2.  When  its  orifice  is  very  small  and  irregular,  it  is  called  hiatus ; 
when  the  opening  is  long,  narrow,  and  resembling  a  crack  or  slit,  it  is  denominated  a 
fissure ;  as  the  sphenoidal  fissure,  the  glenoid  fissure,  &c.  3.  If  the  perforation  runs 
some  way  through  the  substance  of  a  bone,  it  is  called  a  conduit  or  canal ;  as  the  Vidian 
canal,  carotid  canal,  &c. 

There  are  some  canals  which  lodge  the  vessels  intended  for  the  nourishment  of  the 
bone :  these  are  called  nutritious  canals.     They  are  divided  into  three  kinds. 

The  first,  which  belong  exclusively  to  the  shafts  of  long  bones,  and  to  some  broad  bones, 
penetrate  the  substance  of  the  bone  very  obUquely.  These  are  the  nutritious  canals  prop- 
erly  so  called.  Anatomists  carefully  point  out  their  situation,  size,  and  direction,  in  de- 
scribing each  bone. 

The  second  kind  are  seen  on  the  extremities  of  long  bones,  on  the  borders,  or  adjoin- 
ing the  borders,  of  broad  bones.  Cansds  of  this  kind  are  generally  near  the  articular  sur- 
faces. Their  number  is  always  considerable.  Bichat  has  counted  140  on  the  lower  end 
of  the  thigh  bone,  twenty  upon  a  vertebra,  and  fifty  upon  the  os  calcis. 

The  third  kind  of  nutritious  canals  are  exceedingly  small,  and  might  be  denominated 
the  capillary  canals  of  bones.  They  are  found  in  great  numbers  on  the  surfaces  of  all 
bones.  They  may  be  easily  seen  by  the  aid  of  a  good  magnifying  glass  ;  their  presence 
is  also  indicated  by  the  drops  of  blood  which  appear  upon  the  surface  of  a  bone  on  tear- 
ing off  the  periosteum  ;  for  example,  on  the  internal  surface  of  the  cranium,  after  sep- 
arating the  dura  mater.  The  diameter  of  these  little  canals  has  been  calculated  to  be 
about  the  l-20th  of  a  line. 

The  farther  progress  of  the  above-mentioned  canals  is  as  follows  :  those  of  the  first 
kind,  which  belong  to  the  long  bones,  soon  divide  into  two  secondary  canals,  one  ascend- 
ing, the  other  descending,  and  communicating  with  the  central  or  medullary  cavity. 
Tliose  which  are  situated  in  the  broad  bones  form  winding  passages,  which  run  for  a 
considerable  distance  in  the  substance  of  the  bone. 

The  canals  of  the  second  kind  sometimes  pass  completely  through  the  bone  (as  in  the 
bodies  of  the  vertebrae),  and  they  communicate  with  the  spongy  tissue.  The  canals  of 
the  third  kind  terminate  at  a  greater  or  less  depth,  in  the  compact  substance  of  the  long 
bones,  and  in  the  spongy  tissue  of  the  short  bones.  Such  are  the  forms  and  general  ar- 
rangement of  all  the  cavities  which  exist  on  the  surface  of  the  bone  ;  the  following  are 
their  uses  :  1.  They  serve  for  the  reception  and  protection  of  certain  organs  ;  ex.,  the 
occipital  fossa;,  which  receive  a  portion  of  the  cerebellum.  2.  For  insertion  or  surfaces 
of  attachment,  as  those  on  which  muscular  fibres  are  implanted,  as  the  temporal  and 
pterygoid  foss£e.  3.  For  the  transmission  of  certain  organs,  such  as  vessels  and  nerves 
which  have  to  pass  into  or  out  of  an  osseous  cavity ;  such  are  the  fissures,  canals,  fora- 
mina, &.C.  4.  For  increasing  the  extent  of  surface  ;  as  the  sinuses  and  cells  connected 
with  the  organ  of  smelling,  the  surface  of  which  they  greatly  enlarge  by  their  numerous 
anfractuosities.t  5.  For  the  easy  passage  of  tendons,  and  sometimes  for  their  reflec- 
tion, so  that  the  original  direction  of  the  force  is  changed.  To  this  class  belong  the  bi- 
cipital groove  of  the  humerus,  that  for  the  tendon  of  the  obturator  intemus,  &c.  They 
are  generally  converted  into  canals  by  means  of  fibrous  tissue,  which  lines  and  com- 
pletes them.  6.  For  the  nutrition  of  bones,  such  being  the  use  of  the  three  orders  of 
nutritious  canals  already  described.  We  must  mention,  along  with  these  osseous  cavi- 
ties, other  markings  or  impressions  seen  on  the  surface  of  many  bones  ;  for  example, 
the  shallow  depressions  in  the  lower  jaw  bone  for  the  sub-lingual  and  sub-maxillary 
glands,  the  impressions  named  digital  on  the  internal  surface  of  the  cranium. 

As  the  eminences  of  bones  have  been  attributed  to  the  mechanical  effect  of  muscular 
traction,  so  the  various  impressions  and  VEiscular  furrows  upon  the  internal  surface  of 
the  cranium  have  been  considered  to  be  the  result  of  pressure  and  pulsation ;  but  it 
would  be  more  correct  to  limit  ourselves  to  the  simple  statement,  that  the  impressions 
and  eminences  on  the  inside  of  the  cranial  bones  exactly  correspond  with  the  elevations 
and  depressions  on  the  surface  of  the  brain,  and  also  that  the  osseous  furrows  for  the 
middle  meningeal  artery  correctly  represent  the  ramifications  of  that  vessel. 

*  [There  is  great  latitude  amo!ig  anatomical  writers  in  the  use  of  these  terms.] 

t  [Whatever  other  purpose  tliey  may  serve,  such  cells  and  sinuses  are,  in  most  instances,  to  be  regard- 
ed as  a  provision  for  increasing  the  bulk  and  strength  of  bones  without  a  corresponding  augmentation  ol 
weight.T 


\ 


12  OSTEOLOGY. 

We  may  here  point  out  certain  rules  to  be  followed  in  describing  the  external  confor- 
mation of  bones.  1 .  In  describing  the  surface  of  a  bone,  it  should  be  so  divided  that  the 
description  may  comprehend  but  few  objects  at  a  time.  Thus,  a  broad  bone  is  to  be  di- 
vided into  two  surfaces,  into  angles  and  borders,  which  are  to  be  successively  studied. 
2.  The  bone  being  thus  subdivided  into  regions,  each  of  these  is  then  examined,  care 
being  taken  regularly  to  proceed  from  one  part  to  its  opposite,  i.  e.,  to  pass  from  the  su- 
perior to  the  inferior  surface,  and  from  the  anterior  to  the  posterior.  This  is  the  only 
method  which,  in  a  long  description,  will  guard  against  omissions  and  avoid  tiresome 
repetitions.  3.  It  is  also  of  great  importance,  in  considering  the  objects  presented  by 
each  region  or  surface,  to  follow  an  invariable  and  regularly  progressive  order.  Thus, 
after  exposing  the  objects  placed  in  front,  the  examination  should  be  continued  uninter- 
ruptedly from  this  point  backward.  4.  In  the  symmetrical  bones,  it  is  advisable  to  de- 
scribe, first,  the  objects  situated  in  the  median  line,  and  afterward  those  placed  lateraDy. 

Internal  Conformation  of  Bones. — The  tissue  of  bones,  like  that  of  most  other  organs, 
presents  the  appearance  of  fibres,  whose  properties  are  throughout  identical,  but  which, 
by  certain  differences  in  their  mode  of  arrangement,  give  rise  to  two  forms  or  modifica- 
tions of  structure.  To  one  of  these  the  name  of  compact  substance  has  been  given  ;  to 
the  other,  that  of  sjioncry  or  cancellated  substance.  A  subordinate  modification  of  the  lat- 
ter has  long  been  described  under  the  name  of  reticular  tissue. 

The  spongy  or  cellular  substance  has  the  appearance  of  cells  and  areola?,  of  an  irregu- 
lar shape  and  variable  size,  all  of  which  communicate  with  each  other,  and  their  walls 
are  partly  fibrous,  partly  lamellar.  The  compact  substance  seems  to  consist  of  fibres 
strongly  compressed,  so  as  to  form  a  close,  firm  tissue.  It  is  both  fibrous  and  areolar. 
By  means  of  careful  inspection,  softening  the  bone  in  nitric  acid,  and  studying  its  devel- 
opment, it  has  been  clearly  proved  that  it  is  fibrous,  and  that  in  long  bones  the  fibres  are 
arranged  longitudinally,  v.hile  in  broad  bones  they  seem  to  diverge  like  rays  from  the 
centre  to  every  part  of  the  circumference  ;  and  that  in  the  short  bones  they  are  disposed 
irregularly,  so  as  to  form  a  superficial  layer  or  crust.  The  researches  of  Malpighi  have 
conclusively  shown  that  it  is  also  areolar  or  spongy.  By  examining  a  bone  softened  by 
nitric  acid,  or  studying  it  in  the  fcetal  state,  it  may  be  seen  that,  in  fkct,  the  compact  tis- 
sue is  nothing  more  than  an  areolar  substance,  the  meshes  of  which  are  extremely  close 
and  much  elongated.  Accidental  ossifications,  and  the  diseases  of  bone  which  so  fre- 
quently exhibit  the  compact  tissue  converted  into  spongy,  and  the  spongy  changed  into 
compact,  complete  the  demonstration.* 

In  strictness,  therefore,  but  one  form  of  osseous  tissue  can  be  admitted,  namely,  the 
areolar,  which  presents  itself  under  two  aspects,  sometimes  being  close,  compact,  and 
fasciculated ;  sometimes  spongy  and  cellular.  Having  thus  become  acquainted  with  these 
two  forms  of  osseous  tissue,  their  general  arrangement  in  the  different  kinds  of  bones  is 
next  to  be  examined. 

Internal  Structure  of  Long  Bones. — A  vertical  section  of  a  long  bone  presents,  in  the 
body  or  shaft,  a  cylindrical  cavity,  which,  in  the  fresh  state,  is  filled  with  a  soft,  fatty 
substance,  named  the  marrow.  This  cavity,  or  medullary  canal,  is  of  greatest  diameter 
at  the  middle  of  the  shaft ;  and,  as  it  recedes  from  this  point,  it  is  narrowed  and  inter- 
sected at  various  parts  by  lamellae  detached  from  the  sides,  and  forming  a  sort  of  incom- 
plete partitions.  Sometimes,  however,  there  is  a  complete  partition  ;  thus,  I  have  seen 
the  cylinder  of  a  femur  divided  into  two  distinct  halves  by  a  horizontal  partition  situa- 
ted precisely  in  the  middle  of  the  bone.  The  medullary  canal  is  not  regularly  cylindri- 
cal, nor  does  it  correspond  in  figure  with  the  external  surface  of  the  bone.  It  commu- 
nicates with  the  exterior  by  means  of  the  nutritious  canals,  which  sometimes  run,  for  a 
considerable  distance  in  the  substance  of  the  bone,  parallel  to  the  medullary  cavity,  with 
which  they  communicate  by  numerous  apertures,  and  transmit  the  vessels  as  far  as  the 
extremities  of  the  bone.  Some  have  supposed  that  the  cavity  existed  only  in  order  to 
receive  the  man-ow,  while,  on  the  other  hand,  it  has  been  maintained  that  the  marrow 
existed  only  to  fill  up  the  cavity.  Whatever  be  the  uses  of  the  marrow,  it  is  certain 
that  the  existence  of  a  cavity  in  the  centre  of  long  bones  is  an  advantageous  provision 
for  strength  ;  for  it  is  proved  in  physics,  that,  of  two  cylinders,  composed  of  the  same 
material  in  equal  quantity,  the  one  which  is  hollow,  and  whose  diameters  are,  conse- 
quently, greater,  will  offer  greater  resistance  than  that  which  is  solid.  By  the  contri 
vance,  therefore,  of  the  medullary  canal,  there  is  an  increase  of  strength  without  aug- 

*  [The  description  in  the  text  applies  to  the  more  obvious  structure  of  bone  ;  but,  when  examined  with  the 
microscope,  the  osseous  substance,  both  compact  and  spongy,  is  seen  to  consist  of  exceedingly  fine  lamell» 
laid  on  one  another.  In  the  compact  external  crust  of  bones,  these  lamellae  run  parallel  with  the  surface  ; 
they  also  surround,  concentrically,  the  small  cavities  of  the  compact  substance  aad  the  cells  of  the  spongy 
texture,  the  parietes  of  which  they  form.  They  are  not  to  be  confounded  with  the  coarser  layers  and  plates 
described  in  the  compact  substance  by  Gagliardi,  Monro,  and  others  of  the  older  writers.  Along  with  the  la- 
mellce  there  are  minute,  opaque,  white  bodies,  with  extremely  fine  lines  irregularly  branching  out  from  thera. 
These  bodies,  which  can  be  seen  only  with  the  aid  of  the  microscope,  are  named  the  osseous  corpuscules ; 
they  obviously  contain  ralcareous  matter,  and  are,  probably,  minute  ramified  cavities  lined  with  earthy  salts. 
The  earthy  matter  of  bone,  however,  is  not  confined  to  the  corpuscules,  for  the  intermediate  substance  is 
»lfx)  impregnated  with  it.  For  a  representation  of  the  minute  structure  of  bone,  see  Mullefs  Physiology, 
translated  by  Baly,  pkte  1.] 


GENERAL    OBSERVATIONS.  13 

mentation  of  weight.  There  is  another  advantage  in  this  arrangement,  viz.,  the  in- 
crease of  volume  without  corresponding  increase  of  weight ;  for,  since  the  bones  are 
intended  to  give  insertion  to  numerous  muscles,  it  is  necessary  that  their  surfaces 
should  not  be  reduced  to  too  small  dimensions  ;  but  this  must  have  been  the  result  had 
the  walls  of  the  hollow  cylinder  been  compressed  so  as  to  form  a  solid  rod.  The  mar- 
row consists  of  two  distinct  parts  :  1.  The  medullary  membrane,  which  lines  the  walls 
of  the  canal.     2.  The  fatty  tissue,  properly  so  called,  or  the  medullary  hquid. 

The  membrane,  highly  vascular,  serves  to  nourish  the  internal  layers  of  the  bone  :  it 
possesses  great  sensibility  and  a  high  degree  of  vitality.  The  fatty  tissue,  on  the  con- 
trary, is  altogether  insensible.  If  a  probe  be  introduced  into  the  centre  of  the  meduUa 
of  a  long  bone  in  a  living  animal,  no  sign  of  pain  is  evinced  so  long  as  the  instrument  does 
not  touch  the  walls  of  the  cavity ;  but  whenever  the  walls  are  rubbed  or  scratched,  the  pain 
becomes  excessive,  and  is  manifested  by  piercing  cries  and  violent  struggles. 

The  proportion  between  the  thickness  of  the  walls  of  the  cylinder  and  the  diameter  ot 
the  medullary  canal  varies  not  only  in  different  individuals,  but  in  the  same  person  at  dif- 
ferent periods  of  life.  In  the  aged,  the  thickness  of  the  walls  is  proportionally  much  less 
than  in  the  adult :  this  is  one  cause  of  the  great  fragility  of  the  bones  in  old  age.  Some- 
times in  the  adult  the  walls  are  so  thin,  that  the  bone  breaks  by  the  slightest  force  :  in 
such  cases,  there  is  in  some  sort  hypertrophy  of  the  medulla  and  atrophy  of  the  bone. 
It  is  in  such  cases  that  fractures  occur  from  the  simple  effect  of  muscular  contraction, 
or  even  from  moving  in  bed. 

It  is  in  the  central  canal  of  long  bones  that  those  very  deUcate  osseous  filaments  are 
observed,  which,  interlacing  with  each  other,  and  forming  large  meshes,  give  rise  to  that 
variety  of  spongy  tissue  wliich  has  received  the  name  of  reticular,  and  which  appears  in- 
tended to  give  support  to  the  medulla.  The  compact  tissue  diminishes,  and  the  cells 
increase  in  number,  the  greater  the  distance  from  the  centre  of  the  bone,  so  that  the  ex- 
tremities are  entirely  composed  of  spongy  substance  covered  by  a  thin  layer  of  compact 
tissue.  It  appears  that  the  compact  tissue  which  fonns  the  shafts  of  the  bones  divides 
and  subdivides  into  lamellae,  in  order  to  form  the  cells  of  the  extremities.  It  is  easy  to 
perceive  the  advantage  of  a  spongy  structure  in  the  usually  voluminous  extremities  of  the 
long  bones  :  they  could  not  have  been  compact  without  a  great  increase  of  weight,  while 
the  additional  strength  thus  acquired  would  have  been  redundant,  and  altogether  useless. 

The  cells  of  the  spongy  substance  are  filled  by  an  adipose  tissue,  similar  to  that  which 
exists  in  the  bodies  of  long  bones :  from  its  greater  fluidity,  it  has  been  denominated 
meiullary  juice. 

Internal  Structure  of  Broad  Bones. — If  the  surface  of  a  broad  bone  be  scraped,  or  if  the 
bone  be  sawn  across  perpendicularly  or  obliquely,  it  will  be  found  to  consist  of  two  lamellcB 
or  tables,  separated  by  a  greater  or  less  thickness  of  spongy  tissue.  Hence  the  two  plates 
are  insulated,  and  one  may  be  fissured  or  broken  without  injury  to  the  other.  The  thick- 
ness of  the  compact  laminae  and  of  the  spongy  tissue  is  not  uniform  throughout  the  whole 
extent  of  a  broad  bone.  At  the  centre,  for  example,  there  is  scarcely  any  spongy  tissue, 
and  hence  the  transparency  of  the  bone  at  this  part.  Towards  the  circumference,  on 
the  contrary,  the  spongy  tissue  forms  a  very  thick  layer. 

In  the  bones  which  form  the  vault  of  the  cranium,  the  spongy  substance  takes  the 
name  of  diplo'e  {6in?.6og,  double),  because  it  occupies  the  interval  between  the  two  tables. 

From  what  has  been  said  regarding  the  internal  structure  of  broad  bones,  it  is  evident 
that  their  distinctive  character  depends  as  much  upon  their  internal  as  their  external 
conformation,  and  therefore  the  ribs,  which,  according  to  their  external  characters,  seem 
rather  to  belong  to  the  long  bones,  have  been  classed  among  the  broad,  because  they 
exhibit  in  their  internal  structure  the  characters  of  the  latter  kind  of  bones. 

Internal  Structure  of  Short  Bones. — The  extremity  of  a  long  bone,  if  separated  from  the 
shaft,  would  represent  a  short  bone,  both  in  its  external  and  internal  conformation  ;  for 
a  short  bone  is  a  spongy  mass,  covered  by  a  thin  layer  of  compact  tissue.  To  their  spongy 
structure  the  short  bones,  as  well  as  the  extremities  of  the  long,  owe  their  specific  lightness. 

It  should  be  observed,  that  what  has  been  said  concerning  the  internal  structure  of 
bones  applies,  in  strictness,  only  to  those  of  the  adult,  because  the  younger  the  subject,  the 
less  are  the  cells  of  the  spongy  tissue  developed.  And,  in  like  manner,  as  the  walls  of  the 
cylinder  of  long  bones  diminish  in  thickness,  and  the  medullary  cavity  increases  in  diam- 
eter in  the  aged,  so  by  the  progress  of  age  the  walls  of  the  cells  become  extremely  thin, 
and  the  cells  themselves  very  large.  In  some  cases  of  disease,  for  example,  after  white 
swelling  of  the  ankle-joint,  I  have  observed  true  medullary  canals  in  the  cuboid  bone 
and  calcaneum  ;  and  I  have  remarked  in  one  case  of  cancer  of  the  breast,  that  the  ribs 
adjoining  the  tumour  were  hollowed  out  by  a  sort  of  medullary  canal.  It  is  to  this  dimi- 
nution of  the  osseous  substance,  this  kind  of  atrophy  of  the  bone,  that  I  am  disposed  to 
attribute  the  fragility  so  often  observed  in  the  whole  osseous  system  in  cancerous  diseases. 

Chemical  Composition  of  Bones. — The  bony  tissue  consists  essentially  of  two  distinct 
elements,  one  inorganic,  the  other  organized.  When  a  bone  is  subjected  to  the  action 
of  dUute  nitric  acid,  the  salts  are  removed ;  it  becomes  flexible  and  elastic  like  cartilage, 
and  though  retaining  its  original  bulk  and  form,  it  is  found  to  have  lost  a  great  part  of 


T^  OSTEOLOGY. 

its  weight.  By  this  process  its  saline  ingredients  have  been  dissolved,  and  nothing  re- 
mains but  its  organic  constituents,  which,  being  subjected  to  boiling,  present  all  the 
characters  of  gelatine. 

On  the  other  hand,  if  a  bone  be  calcined,  the  whole  of  its  organic  matter  is  destroyed, 
giving  out  during  the  process  the  odour  of  burned  horn.  A  substance  remains  which 
preserves  exactly  the  shape  and  size  of  the  original  bone,  but  at  the  same  time  is  very 
light,  porous,  and  so  friable  that  it  crumbles  to  powder  under  the  slightest  pressure.  If 
the  calcination  be  complete,  the  bone  is  rendered  perfectly  white,  but  it  is  black  when 
the  burning  has  not  been  carried  sufficiently  far ;  it  m^y  even  be  vitrified  by  a  more  in- 
tense heat  applied  for  a  longer  time.  Prolonged  exposure  to  the  action  of  air  and  moist- 
ure in  like  manner  remove  the  organized  substance,  and  leave  only  a  calcareous  residue. 
The  two  elements  of  bone  do  not  bear  the  same  proportion  at  different  ages.  Certain 
diseases  greatly  affect  the  predominance  of  one  or  the  other,  producing  almost  the  ssune 
effects  as  chemical  agents. 

To  the  inorganic  matter  the  bones  owe  their  hardness  and  durability ;  to  the  organized 
substance  they  are  indebted  for  their  vitality  and  the  slight  degree  of  flexibility  and  elas- 
ticity which  they  possess. 

The  following  are  the  results  furnished  by  the  cKemical  analysis  of  M.  Berzelius : 

1.  Okganized  Part  \  ^  Animal  matter  reduced  to  gelatine  by  boiling     .  32-17 
12.  Insoluble  animal  matter rlS 

{Phosphate  of  lime 51'04 
Carbonate  of  lime       .......  ll'SO 
Fluate  of  lime             2'0 
Phosphate  of  magnesia                ri6 
Soda  and  chloride  of  sodium 1"20 

The  bones  are  furnished  with  vessels :  by  one  set  arterial  blood  is  transmitted,  by 
another  venous  blood  is  returned. 

1.  The  arteries  are  of  three  orders,  corresponding  with  the  osseous  canals,  which  have 
been  described  in  speaking  of  the  cavities  of  bones. 

First  Order,  or  Arteries  of  the  Medullary  Canal  of  Long  Bones. — In  each  medullary  canal 
there  is  at  least  one  principal  artery  which  enters  by  the  nutritious  canal  and  divides 
almost  immediately  into  two  branches,  one  ascending,  the  other  descending.  These 
subdivide  into  an  infinite  number  of  small  branches,  the  interlacements  of  which  form 
that  vascular  network  called  the  medullary  membrane.  With  this  network  the  vessels 
of  the  second  order  freely  anastomose  after  their  entrance  at  the  extremities  of  the  bone. 
In  consequence  of  this  important  communication,  the  vessels,  notwithstanding  the  great 
difference  in  the  manner  of  their  entering  the  bone,  can  reciprocally  supply  each  other 
with  blood.  In  illustration  of  this,  Bichat  relates  a  singular  case,  in  which  the  nutritious 
foramen  of  a  tibia  was  completely  obliterated,  and  yet  the  nutrition  of  the  bone  was  un- 
impaired. The  medullary  artery  gives  off  the  twigs  for  those  layers  of  compact  tissue 
which  form  the  parietes  of  the  medullary  cavity. 

The  arteries  of  the  second  order,  destined  for  the  spongy  tissue,  enter  the  bones  by  the 
nutritious  foramina  of  the  second  order ;  but  their  number  by  no  means  corresponds  with 
that  of  the  foramina,  which  are  for  the  most  part  destined  for  the  transmission  of  veins. 
These  arteries  communicate  hoth  with  the  medullary  artery  already  mentioned  and  vdth 
the  arteries  of  the  periosteum. 

The  arteries  of  the  third  order,  or  the  periosteal  arteries,  are  exceedingly  numerous.  This 
class  comprehends  the  innumerable  httle  arteries  which,  after  ramifying  in  the  perioste- 
um, enter  the  bone  by  the  minute  canals  of  the  third  order.  These  small  vessels,  spe- 
cially distributed  to  the  exterior  layers  of  compact  substance,  anastomose  with  the  two 
preceding  orders  of  vessels. 

2.  The  veins  of  bones  follow  the  course  of  the  arteries.  But  there  are  peculiar  venous 
canals  in  the  interior  of  the  broad  and  the  short  bones,  and  in  the  spongy  extremities  of 
the  long  bones.  These  canals  were  first  described  by  M.  Dupuytren  in  the  cranial  bones, 
where  they  are  very  obvious  :  they  are  perforated  with  lateral  openings,  by  which  they 
receive  blood  from  the  adjoining  parts ;  their  parietes  are  formed  by  a  very  thin  plate  of 
compact  tissue,  and  they  are  lined  by  a  prolongation  of  the  internal  membrane  of  the 
veins.  We  shall  afterward  see  that  there  is  a  complete  analogy  between  these  venous 
canals  and  the  sinuses  of  the  dura  mater,  the  only  difference  being  in  the  nature  of  their 
parietes,  which  are  fibrous  in  the  sinuses,  but  bony  in  the  canals  in  question.  I  have 
remarked,  that  in  the  foetus  and  new-bom  infants,  the  cells  of  the  spongy  tissue,  which 
subsequently  contain  adipose  matter,  are  filled  with  venous  blood. 

Lymphatic  vessels  have  not  yet  been  actually  demonstrated  in  the  bony  tissue  ;  but  it 
is  probable  that  they  really  exist  there ;  at  least,  the  process  of  nutrition  in  bones,  and 
certain  morbid  phenomena  which  they  present,  lead  to  the  beUef  of  their  existence. 

The  cellular  tissue  also  enters  into  the  composition  of  the  bones  :  it  contributes  to  form 
their  fibrous  structure. 

Nerves  can  be  demonstrated  in  connexion  with  most  of  the  bones  of  the  skeleton. 
But  it  is  necessary  to  distinguish  those  nerves  which  merely  pass  through  the  bones 
from  those  which  are  distributed  on  their  substance. 


DEVELOPMENT    OF    BONES.  J|^ 

Development  of  Bones,  or  Osteogeny. 

From  the  time  of  their  first  appearance  in  the  foetus,  to  the  period  of  their  complete 
development,  the  bones  pass  through  a  series  of  changes,  which  constitute  one  of  the 
most  important  circumstances  in  their  history.  The  investigation  of  these  changes,  or 
of  the  successive  periods  of  development,  is  the  object  o{  osteogeny. 

The  development  of  the  bones,  considered  generally,  presents  three  phases  or  periods, 
designated  by  the  name  mucous,  cartilaginous,  and  osseous  stage. 

1.  The  mucous  stage.  The  mucous  condition,  the  cellular  of  some  authors,  has  not 
been  well  defined.  Some  apply  the  term  to  that  period  of  formation  in  which  the  bonea 
and  the  other  organs  of  the  body  form  but  one  homogeneous  mass  of  a  mucous  aspect 
others  use  the  term  to  signify  a  more  advanced  stage,  in  which  the  bones,  acquiring  a 
greater  consistence  than  the  surrounding  parts,  begin  to  show  their  development  through 
these  more  transparent  tissues.  In  the  latter  sense,  the  mucous  stage  is  obviously  no- 
thing but  the  commencement  of  the  cartilaginous,  and  therefore  the  first  acceptation  is 
the  only  one  to  be  retained. 

2.  The  cartilaginous  stage  succeeds  the  mucous,  though  the  time  of  the  transition  from 
the  one  to  the  other  has  not  been  precisely  ascertained.  Several  anatomists  are  of  opin- 
ion, with  Mr.  Howship,  that  the  cartilaginous  state  does  not  necessarily  intervene  be- 
tween the  mucous  and  osseous  conditions  ;  that  its  occurrence  is  only  satisfactorily  de- 
monstrated in  such  bones  as  are  late  in  ossifying,  and  that  it  constitutes  a  sort  of  provis- 
ional condition,  in  which  the  cartilage  is  employed  to  perform  the  office  of  bone.  Bui 
when  we  take  into  consideration,  in  the  first  place,  the  rapid  transition  from  the  cartila- 
ginous to  the  osseous  stage  in  certain  bones,  and,  secondly,  the  translucency  of  newly- 
formed  cartilage  when  of  inconsiderable  thickness,  as  in  the  cranium,  where  the  carti- 
lage is  scarcely  to  be  distinguished  from  the  two  membranes  between  which  it  is  placed, 
we  can  conceive  that  the  cartilaginous  stage  may  easily  have  been  overlooked.  On  the 
other  hand,  the  constant  result  of  my  observations  proves  that,  in  the  natural  process  of 
ossification,  every  bone  passes  through  the  state  of  cartilage. 

When  the  different  pieces  of  the  skeleton  assume  the  cartilaginous  condition,  the 
change  occurs  throughout  their  whole  substance  at  once.  The  notion  of  central  points 
of  cartilaginification,  corresponding  with  the  points  of  ossification,  is  purely  hypotheti- 
cal :  a  bone  becomes  cartilaginous  in  all  parts  simultaneously,  and  never  by  insulated 
points.     The  cartilage  has  the  same  figure  as  the  future  bone. 

Bones  which  are  to  be  permanently  united  by  intermediate  cartilage,  are  formed  from 
m  ;.  imitive  piece  of  cartilage,  as  those  of  the  cranium  and  face  :  those,  on  the  other 
haau,  which  are  connected  together  only  by  ligaments,  are  distinct  and  separable  while 
in  the  cartilaginous  -state. 

3.  The  osseous  stage.  The  cartilaginous  condition  of  the  skeleton  is  completed  by 
the  end  of  the  second  month  ;*  but  ossification  conunences  in  several  places  long  before 
this  period.  The  first  point  of  ossification  appears  after  the  fourth  week  in  the  clavicle  ; 
the  second,  in  the  lower  jaw.  From  the  thirty-fifth  to  the  fortieth  day  points  of  ossifica- 
tion appear  sometimes  successively,  in  other  cases  simultaneously,  in  the  thigh-bone, 
the  humerus,  the  tibia,  and  upper  jaw-bone.  From  the  fortieth  to  the  fifty-fifth  day, 
points  of  ossification  appear  at  short  intervals  in  the  annular  portion  of  the  uppermost 
vertebrse,  in  the  bodies  of  the  dorsal  vertebrae,  in  the  ribs,  the  tabular  bones  of  the  scull, 
the  fibula,  the  scapula,  the  ilium,  the  nasal,  palatine,  and  metacarpal  bones,  the  phalan- 
ges of  the  fingers  and  toes,  the  metatarsus,  &c.  Once  commenced,  the  ossification  pro- 
ceeds with  more  or  less  rapidity  in  the  different  bones  during  the  remainder  of  intra- 
uterine hfe. 

In  the  child  at  birth,  the  shafts  of  the  long,  as  well  as  the  broad  bones,  are  far  advan- 
ced in  development.  As  to  the  short  bones,  the  vertebrae  are  scarcely  less  early  in  their 
evolution  than  the  long  and  broad  bones  ;  the  calcaneum,  cuboid,  and  sometimes  the  as- 
tragalus, have  points  of  ossification,  but  only  commencing.  The  extremities  of  the  long 
bones,  with  a  single  exception,  the  lower  end  of  the  femur,  are  as  yet  without  ossifying 
points.  The  remaining  short  bones  and  extremities  of  long  bones  ossify  subsequently. 
Of  the  tarsal  bones,  the  scaphoid  is  the  last  to  ossify ;  the  pisiform  is  the  latest  among 
the  carpal  bones ;  the  patella  is  ossified  at  the  age  of  three  years. 

In  regard  to  the  process  of  ossification,  a  question  of  the  highest  interest  presents  it- 
self, viz..  Is  the  successive  appearance  of  the  centres  of  ossification  governed  by  any  general  law? 

The  order  of  commencement  of  the  points  of  ossification  is  in  no  way  dependant  on 
the  size  of  the  bones.  It  is  true  that  the  smaller  bones,  excepting  the  ossicles  of  the 
ear,  are  later  in  appearing ;  but,  at  the  same  time,  it  is  not  the  largest  bones  that  are  the 
earliest ;  thus,  the  bones  of  the  pelvis  appear  long  after  the  clavicle. 

*  [The  relative  time  of  ossification  of  the  different  bones,  or,  at  least,  the  order  in  which  it  commences  in 
them,  is  easily  determined  ;  but  owing  to  the  uncertainty  respecting  the  age  of  the  embryo  in  its  early  stages, 
the  absolute  time  of  foetal  life  at  which  each  bone  begins  to  ossify  is  very  uncertain,  and,  accordingly,  the 
statements  of  many  anatomists  differ  from  that  given  in  the  text :  thus  the  seventh  week  is  assigned  by  some 
as  the  period  when  ossification  commences  in  the  clavicle.     The  age  fixed  by  the  author  appears  too  early.] 


16  OSTEOLOGY. 

Proximity  to  the  heart  or  great  vessels  has  no  effect  on  the  precocity  of  development. 
Though  the  ribs  vt'hich  are  near  the  heart  ossify  speedily,  the  breast-bone,  on  the  other 
hand,  which  is  still  nearer,  is  one  of  the  bones  latest  in  ossifying.  Again,  the  anterior 
and  inferior  angle  of  the  parietal,  which  is  close  to  the  anterior  branch  of  the  middle 
meningeal  artery,  is  the  part  of  the  bone  which  last  ossifies.  The  femoral  artery  lies  on 
the  confines  of  the  os  pubis  and  ilium,  which  at  that  part  long  remain  cartilaginous. 

The  true  law  which  governs  the  order  of  appearance  of  the  points  of  ossification  is 
this,  viz.,  that  the  period  of  formation  is  earlier  or  later  in  the  several  bones  according 
to  the  period  at  which  they  are  required  to  fulfil  their  oflice  in  the  economy.  Thus,  the 
jaws  being  required  to  act  immediately  after  birth,  are  ossified  before  the  other  bones  of 
the  head.  In  the  same  way,  the  ribs,  destined  for  a  function  which  must  commence 
from  the  moment  of  birth,  are  for  this  purpose  completely  ossified :  the  vertebrae  and 
bones  of  the  cranium  appear  early,  because  of  their  use  as  protecting  the  spinal  cord  and 
brain  ;  and  it  is  thus  that  the  pretended  correspondence  between  the  rapidity  of  ossifica- 
tion and  proximity  to  the  nervous  centres  is  explained. 

Although  several  of  the  bones  are  completed  solely  by  an  extension  of  the  primitive 
nuclei  of  ossification,  the  greater  number  acquire,  in  addition  to  these  principal  or  es- 
sential pieces,  complementary  points  of  ossification  named  epiphyses.  Thus,  while  in 
the  frontal  the  two  original  points  of  ossification  suffice  by  their  extension  for  the-  com- 
pletion of  the  bone,  the  vertebrse,  on  the  other  hand,  have  three  primary  osseous  nuclei, 
one  for  the  body,  and  two  for  the  laminae  and  processes ;  and  five  complementary  pieces 
of  ossification,  namely,  two  for  the  body,  and  one  each  for  the  tips  of  the  spinous  and 
transverse  processes. 

The  transition  from  the  state  of  cartilage  to  bone  is  attended  with  the  following  phenom- 
ena :  the  cartilage  becomes  more  dense  ;  its  colour  is  at  first  a  dull  white,  but  subse- 
quently changes  to  deep  yellow ;  small  irregular  cavities  are  formed  in  its  substance ; 
red  vessels  show  themselves  ;  a  bony  point  appears  in  the  midst  of  these  vessels,  and 
this  bony  nucleus  is  spongy  and  penetrated  with  blood.  The  ossification  spreads  by  lit- 
tle and  little,  always  preceded  by  a  great  development  of  vessels ;  so  that,  in  attentively 
examining  an  ossifying  cartilage,  we  find  first  an  osseous  point,  then  a  red  zone,  next 
an  opaque  layer  of  cartilage  which  is  permeated  by  canals,  and,  lastly,  the  remaining  car- 
tilage traversed  only  by  a  few  vascular  canals  which  run  towards  the  point  of  ossifica- 
tion. Moreover,  it  is  always  at  some  aepth  within  the  substance  of  the  cartilage  that 
the  first  osseous  points  appear,  and  never  at  the  surface.  It  is  only  in  cases  of  accident- 
al or  diseased  ossification,  as  in  the  cartilages  of  the  ribs,  that  it  occasionally  begins  at 
the  surface.  It  is  unnecessary  to  pursue  farther  the  immediate  process  of  ossification  • 
nor  need  we  here  discuss  the  purely  speculative  question,  whether  the  bone  is  really  a 
new  part  essentially  distinct  from  the  cartilage,  which  is  absorbed  and  gives  place  to  it, 
or  merely  a  deposite  of  earthy  phosphate  in  a  cartilaginous  tissue. 

In  admitting  that  ossification  is  always  preceded  and  accompanied  by  a  great  devel- 
opment of  vessels,  a  fact  proved  incontestably  by  Haller  and  Bichat,  I  must,  neverthe- 
less, decidedly  dissent  from  the  opinion  that  the  appearance  of  blood  in  a  cartilage  is  a 
constant  indication  of  approaching  ossification;  for  several  cartilages  have  naturally 
bloodvessels,  as  may  be  seen  in  the  cartilages  of  the  ribs  and  larynx. 

Tlie  study  of  the  development  of  the  bones  does  not  consist  merely  in  determining  the 
number  and  time  of  appearance  of  their  points  of  ossification :  it  comprehends,  also,  the 
ulterior  changes  which  take  place  in  the  osseous  system,  viz.,  the  union  of  the  primitive 
points  of  ossification,  and  the  appearance  and  junction  of  the  complementary  points  of  ossifica- 
tion. It  is  to  be  remarked,  that  the  order  of  development  and  union  of  the  points  of  os- 
sification does  not  always  correspond  with  that  in  which  they  originally  appear ;  nay,  it 
is  often  the  reverse.  Thus,  the  lower  epiphysis  of  the  femur  is  the  earliest  in  appearing, 
and  it  is  the  last  in  joining ;  while,  on  the  other  hand,  the  upper  end  of  the  radius  is  one 
of  the  latest  of  the  epiphyses  in  appearing,  but  is  joined  to  the  bone  before  all,  or  nearly 
all,  the  rest.  The  junction  of  the  pieces  of  ossification  is  not  complete  till  about  the  age 
of  twenty-five  years,  at  which  time  the  lower  epiphysis  of  the  femur  unites  with  the  body 
of  the  bone. 

General  Mode  of  Ossification  of  Eminences  and  Cavities. — M.  Serres,  in  a  very  remarka- 
ble work,  has  given,  under  the  title  of  General  Laws  of  Osteogeny,  the  results  of  his  ob- 
servations concerning  the  development  of  azygos  or  median  bones,  and  of  eminences 
and  cavities  ;  and  with  a  rapid  notice  of  these,  we  shall  conclude  what  is  to  be  said  on 
the  points  of  ossification. 

1.  By  the  law  of  symmetry,  which,  according  to  M.  Serres,  governs  the  development 
of  all  bones  situated  on  the  median  line,  every  such  bone  is  originally  double,  that  is, 
composed  of  two  separate  halves,  which,  advancing  to  meet  each  other,  are  at  last  join- 
ed. Thus  there  are  originally  two  osseous  halves  of  the  spinal  column,  and  two  demi- 
sterna.  The  basilar  portion  of  the  occipital,  the  body  of  the  sphenoid,  the  cribriform 
plate  of  the  ethmoid,  the  vomer,  and  the  spinous  processes  of  the  vertebrae,  have,  ac- 
cording to  this  view,  originally  been  double.  But  this  law  has  many  exceptions.  Thus, 
although  some  of  the  pieces  of  the  sternum  are  conunonly  formed  from  two  lateral 


DEVELOPMENT   OF   BONES.  iT 

points,  the  first  and  the  last  are  always,  or  almost  always,  developed  from  a  single  point 
in  their  middle.  The  bodies  of  the  vertebrae  are  most  commonly  formed  from  a  single 
primitive  nucleus  :  the  same  is  the  case  with  the  basilar  portion  of  the  occipital,  the  per- 
pendicular plate  of  the  ethmoid,  the  vomer,  and  the  spinous  processes  of  the  vertebrae. 
Instances  of  incomplete  division  of  bones  on  the  median  Une  must  not  be  adduced  in 
proof  of  the  existence  of  two  primitive  points  of  ossification. 

2.  Every  eminence,  according  to  M.  Serres,  is  developed  by  a  special  point  of  ossifi- 
cation. This  is  true  generally :  but  how  many  eminences  are  formed  merely  by  the  ex- 
tension of  ossification  from  the  piece  which  supports  them !  Where,  it  may  be  asked,  is 
the  special  point  of  ossification  for  the  articular  processes  of  the  vertebrae,  the  coronoid 
process  of  the  ulna,  the  external  and  internal  protuberances  of  the  occipital,  &c.  1  There 
are  even  double  eminences  developed  from  a  single  point,  £is  the  condyles  of  the  femur. 

SPEvery  cavity  is  formed  by  the  union  of  at  least  two  pieces  of  ossification ;  so  that, 
when  a  bone  furnished  with  a  cavity  consists  of  several  pieces,  the  place  of  junction  of 
these  pieces  is  at  the  cavity.  Thus,  the  three  pieces  of  the  os  innominatum  meet  together 
at  the  cotyloid  cavity.  The  same  law,  according  to  M.  Serres,  regulates  the  formation 
of  the  foramina  and  osseous  canals  of  every  kind,  as  the  medullary  cavity  of  the  long 
bones,  all  the  canals  for  vessels  and  nerves,  as  the  carotid,  vidian,  &c. :  according  to 
the  same  law,  all  the  foramina  in  the  bones  of  the  scuU  are  formed  originally  of  two 
halves.     But  the  facts  are  opposed  to  this  doctrine  when  applied  so  universally. 

Progress  of  Ossification  in  the  three  Kinds  of  Bones. — 1.  In  the  loTig  hones.  Ossifica- 
tion commences  in  their  middle  part.  A  small  cylinder  of  bone  appears,  narrow  in  the 
middle,  expanded  at  the  ends,  tubular  within,  perforated  already  with  the  nutritious  fo- 
ramen, which  is  very  obvious,  and  receives  very  large  vessels.  This  Uttle  cylinder  grows 
gradually  thicker  and  longer,  extending  towards  the  extremities  of  the  bone,  which  it 
reaches  about  the  time  of  birth  ;  while  at  this  period  the  ossification  is  so  far  advanced 
in  the  body  of  the  long  bones,  their  extremities  are  not  yet  osseous.  It  is  only  at  later 
periods,  varying  in  different  bones,  that  an  osseous  nucleus  appears  in  the  cartilaginous 
extremities,  increasing  and  encroaching  upon  the  portion  of  cartilage  which  separates  it 
from  the  bony  shaft,  until  that  cartilaginous  partition,  gradually  becoming  thinner,  is  at 
last  itself  invaded  by  the  ossification.  All  the  long  bones  have  two  essential  or  princi- 
pal epiphyses,  to  which  complementary  epiphyses  are  sometimes  added.  The  phalan- 
ges* are  an  exception ;  they  have  only  one.  It  is  this  process  which  is  named  junction 
of  the  epiphyses.  The  time  of  its  completion  is  not  confined  to  any  very  definite  limits, 
but  it  is  over  by  twenty  or  twenty-five  years. 

Throughout  the  whole  time  of  development  the  growth  in  length  takes  place,  chiefly 
by  ossification  of  the  intermediate  cartilage,  which  separates  the  epiphyses  from  the 
shaft,  but  partly,  also,  by  longitudinal  expansion  of  the  ossified  shaft  itself  The  former 
mode  of  increase  has  been  satisfactorily  established  by  Hunter ;  the  latter  is  proved  by 
the  following  experiment  of  Duhamel :  Three  needles  being  fixed  in  the  shaft  of  a  long 
bone  of  a  bird,  at  measured  distances,  it  is  found  that  after  a  certain  time  they  become 
farther  separated,  which  proves  that  the  osseous  cylinder  has  undergone  an  elongation. 

2.  In  the  broad  bones.  1.  Among  the  broad  bones,  those  which  are  symmetrical  often 
conmience  by  two  points  placed  one  on  each  side  of  the  median  line.  2.  The  asymmet- 
rical bones  are  developed  sometimes  from  a  single  point  of  ossification,  as  the  parietal ; 
sometimes  by  several,  as  the  temporal. 

One  of  the  most  remarkable  circumstances  in  the  development  of  broad  bones  is  the 
sort  of  radiation  by  which  the  deposition  of  calcareous  phosphate  extends,  which  spreads 
from  the  centre  where  the  first  osseous  point  was  deposited,  and  advances  by  divergent 
rays  to  all  points  of  the  circumference,  forming  bony  striae  separated  by  intervals,  which 
are  soon  filled  up  by  new  osseous  rays.  As  these  rays  are  of  unequal  length,  and  are 
separated  at  the  circumference  by  intervals  of  greater  or  less  extent,  it  follows  that  a 
broad  bone  in  the  process  of  ossification  must  have  at  its  circumference  a  scalloped  or 
jagged  border,  like  the  toothed  edge  of  a  comb.  It  is  this  form  of  ossification  which 
gives  rise  to  the  serratures  of  the  sutures. 

The  broad  bones  are  proportionally  much  thinner  in  the  early  periods  of  ossification 
than  subsequently,  because  at  first  the  spongy  texture  is  scarcely  developed.  At  the 
time  of  birth,  the  primary  pieces  of  ossification  not  having  united  except  in  very  few 
places,  and  the  ossification  which  spreads  from  the  centre  of  the  bones  not  having  yet 
reached  the  limits  of  their  circumference,  it  follows  that  the  constituent  parts  of  bones, 
and  the  edges  of  different  bones  which  are  destined  in  the  end  to  meet  together,  are  at 
this  period  separated  by  cartilaginous,  and,  in  some  measure,  membranous  intervals, 
which  in  the  cranium  constitute  the  fontanelles.  After  birth,  ossification  spreads  more 
and  more  in  the  broad  bones  ;  at  the  same  time  they  increase  in  hardness  and  thickness, 
appearing  as  if  to  separate  into  two  plates  or  tables,  the  interval  between  which  be- 
comes filled  with  spongy  tissue. 

The  epiphysary  or  complementary  points  of  ossification  of  some  of  the  broad  bones 

*  [Also  the  clavicle,  the  metatarsal,  and  usually  the  metacarpal  bones.] 

c 


1 8  OSTEOLOGY. 

represent,  in  a  certain  degree,  the  epiphyses  of  the  long  bones.  They  occupy  the  cu- 
cumference,  and  are  thence  named  marginal  epiphyses.  Thus,  in  the  cartilaginous  bor- 
der of  the  haunch-bone,  which  represents  the  crest  of  the  ilium,  a  point  of  ossification 
commences,  and  extending  along  its  whole  length,  forms  a  marginal  epiphysis,  which 
subsequently  joins  the  rest  of  the  bone,  and  in  this  respect  is  perfectly  analogous  to  the 
epiphyses  at  the  extremities  of  the  long  bones.  The  epiphyses,  then,  are  not  an  exclu- 
sive attribute  of  the  long  bones,  as  Bichat  maintained.  They  are  found,  also,  in  some  of 
the  short  bones.  But  it  would  be  indulging  in  a  false  analogy  to  class  the  Wormian 
bones,  formed  during  the  development  of  the  cranium,  with  the  epiphyses  of  the  long 
and  the  broad  bones  ;  for  they  have  peculiarities  which  are  never  found  in  true  epiphy- 
ses. Thus,  1.  They  are  not  joined  by  osseous  union,  as  is  the  case  with  epiphyses,  but 
always  by  suture.  2.  There  is  no  constancy  in  their  time  of  appearance,  nor  in  ^eir 
figure,  which  is  irregular,  nor  in  their  size,  which  is,  in  general,  greater  the  earlierlftey 
have  appeared,  because  they  have  then  had  longer  time  to  extend  themselves  before 
meeting  the  neighbouring  bones. 

From  what  has  been  said,  we  conclude  that  the  broad  bones  have  a  twofold  mode  of 
mcrease  in  breadth,  namely,  the  successive  addition  of  bony  substance  to  their  borders, 
and  the  formation  of  marginal  epiphyses.  In  every  broad  bone  which  is  formed  from 
several  pieces,  and  which  has  on  its  surface  a  part  for  articulation,  this  last  becomes 
the  centre  in  which  the  different  pieces  meet,  and  are  ultimately  joined  when  the  ossi 
fication  is  completed. 

3.  In  the  short  bones.  These  are  the  latest  in  being  ossified ;  a  great  number  of  them 
are  still  cartilaginous  at  birth.  The  short  bones  are  not  destitute  of  epiphyses,  as  is 
proved  by  the  ossification  of  the  vertebrae  and  calcaneum.  Their  ossification,  in  fine, 
presents  the  same  phases,  and  follows  the  same  progress,  as  that  of  the  extremities  of 
the  long  bones,  which  they  resemble  in  so  many  respects. 

Changes  which  take  place  in  Bones  after  Maturity. 

To  obtain  a  complete  notion  of  the  development  of  the  bones,  we  must  not  rest  satis- 
fied with  ascertaining  the  number  of  points  of  ossification,  their  successive  appearance, 
and  their  mode  of  junction  ;  we  must  also  study  the  changes  which  they  undergo  after 
they  have  attained  their  full  growth. 

The  increase  of  the  bones  in  height  teraiinates  when  their  several  pieces  have  become 
united :  the  time  when  this  is  accomplished  varies  from  the  age  of  twenty  to  thirty 
years ;  but  they  continue  to  increase  in  thickness  for  a  considerable  time  longer.  In 
proof  of  this,  we  need  only  compare  the  bones  of  a  young  man  with  those  of  an  adult  of 
forty.  In  old  age  the  bones  still  undergo  important  changes  :  the  medullary  canal  of  the 
long  bones  augments  in  width,  and  the  tliickness  of  its  parietes  diminishes  in  proportion ; 
and  something  similar  takes  place  in  the  broad  and  the  short  bones. 

Another  important  fact  to  be  here  mentioned  is,  that  the  relative  proportion  of  calca- 
reous phosphate  and  animal  matter  undergoes  continual  changes  in  the  course  of  life. 
Thus,  by  an  analysis  of  Dr.  I.  Davy,  it  was  shown  that  the  proportion  of  calcareious  phos- 
phate was  a  fifth  less  in  a  child  of  fifteen  years  than  in  the  adult.  The  same  chemist 
found  that  the  proportion  of  phosphate  of  lime  in  an  adult  occipital  was  to  that  in  an 
occipital  bone  of  an  aged  person  as  sixty-four  to  sixty-nine. 

JSTutrition  of  Bones. 

The  fact  of  the  nutrition  of  bones,  and  the  process  of  composition  and  decomposition 
in  which  it  consists,  appear  to  me  to  be  demonstrated  by  the  experiment  with  madder. 
If  an  animal  is  fed  for  some  time  with  food  impregnated  with  thfe  juice  of  madder,  its 
bones  soon  become  coloured  red,  as  may  be  ascertained  by  ampirfttfang  a  limb  ;  but,  by 
suspending  the  use  of  that  substance  for  some  time,  the  bones  recover  their  natural  col- 
our. In  this  experiment,  there  is  no  doubt  that  the  calcareous  phosphate  is  the  vehicle 
of  the  colouring  matter,  for  the  bones  are  the  only  parts  that  become  coloured  ;  aU  that 
is  cartilaginous  remains  free  from  colour.  We  may  infer  from  this  that  a  twofold  move- 
ment continually  goes  on  in  bones,  by  which  new  molecules  are  first  deposited  and  then 
removed,  after  they  have  for  a  longer  or  shorter  period  formed  part  of  these  organs.* 

The  administration  of  madder,  moreover,  demonstrates  a  fact,  which  was  proved  by 
Duhamel  du  Monceau  in  a  very  curious  set  of  experiments,  namely,  that  the  growth  of 
bones  takes  place  by  the  successive  deposition  of  new  layers,  formed  by  the  undermost 
or  contiguous  layers  of  the  periosteum.  Thus,  let  a  pigeon  be  fed  with  food  impregnated 
with  madder,  suspend  the  use  of  the  madder  for  a  time,  then  renew  it ;  after  this,  the 
bones,  when  cut  through,  exhibit  a  red  layer  next  their  surface,  then  a  white  layer,  then 
a  red  layer  again. 

Thus  the  bones  grow  in  two  ways,  namely,  by  the  interstitial  mode  of  groAvth,  or  by 
intussusception,  which  they  have  in  common  with  the  other  tissues ;  and,  secondly,  by 
juxtaposition. 

*  A  somewhat  subtle  objection  would  be  the  following :  May  not  the  colouring  matter  be  deposited  and 
again  carried  off  without  the  particles  of  phosphate  of  lime  being  necessarily  subject  to  the  same  vicissitudes  ! 


THE    VERTEBRAL    COLUMN. 


19 


THE  VERTEBRAL  COLUMN. 

Gene-al  Characters  of  the  Vertehra. — Characters  peculiar  to  the  Vertehra  of  each  Region. 
— Characters  proper  to  certain  Vertcbree. — Vertebrae  of  the  Sacro-Coccygeal  Regvm. — Tht 
Vertebral  Column  in  general. — Development. 

The  vertebral  column  (from  the  Latin  word  vertere,  to  turn,  because  ^'  *• 

the  body  turns  round  this  as  an  axis),  spine,  or  rachis,  is  that  long,  flex-  c  _;  <i 
ible,  hollow,  bony  stem,  the  principal  lever  of  the  body,  which  affords 
support  to  almost  the  entire  skeleton,  and,  at  the  same  time,  shields 
and  protects  the  spinal  marrow.  It  is  situated  at  the  posterior  and 
median  portion  of  the  trunk,  extending  from  the  cranium  to  the  pelvis, 
where  it  terminates  in  two  osseous  pieces,  tiie  sacrum  and  coccyx, 
which  may,  in  fact,  be  regarded  as  a  continuation  of  the  column.  The 
sacrum  and  the  coccyx  have  been  separated  from  the  vertebral  column 
merely  on  account  of  the  osseous  junction  of  the  vertebrae  of  which 
they  are  composed.*  It  is  articulated  with  the  base  of  the  cranium 
at  the  part  where  the  posterior  joins  the  two  anterior  thirds  of  this 
cavity  :  it  corresponds  with  the  posterior  portion  of  the  pelvis,  an  ar- 
rangement most  favorable  for  maintaining  the  erect  position. 

The  vertebral  column  is  situated  behind  the  alimentary  canal  in 
man,  above  it  in  the  lower  animals.  In  front  are  suspended  the  or- 
gans of  respiration  and  circulation,  to  which  it  affords  protection,  and 
which  constantly  tend  to  incline  it  forward  :  to  its  sides  are  attached 
the  ribs  and  the  extremities,  the  thoracic  having  an  indirect  and 
movable,  the  abdominal  a  fixed  connexion. 

From  the  limits  here  assigned  to  the  vertebral  column,  it  follows 
that  this  part  of  the  skeleton  extends  the  whole  length  of  the  trunk, 
forming  the  entire  osseous  support  of  the  neck  and  loins,  the  poste- 
rior column  of  the  thorax,  and  even  the  posterior  wall  of  the  pelvis. 
Hence  it  is  divided  into  four  regions,  viz.,  a  cervical,  a  dorsd  or  tho- 
racic, an  abdominal,  and  a  pelvic  or  sacro-coccygeal  region. 

The  vertebral  column  (fig.  1)  is  composed  of  twenty-six  bones 
piled  above  each  other :  the  last  two  have  received  the  names  of 
sacrum  and  coccyx,  and  the  others,  which  constitute  the  vertebred  col-- 
umn,  properly  so  called  (a  d),  are  denominated  vertebra :  they  have 
also  been  called  true  vertcbree,  as  distinguished  from  the  false  vertc- 
bree, which,  by  their  osseous  union,  form  the  sacrum  {d  e)  and  coccyx 
(c/).  The  sacrum  is  composed  of  five  of  these  false  vertebrae,  and 
the  coccyx  of  four,  in  a  rudimentary  state.  The  description  of  these 
latter  bones  will  be  deferred,  in  the  mean  time.  The  first  seven  true 
vertebrae  form  the  cervical  region  (a  b) ;  the  twelve  which  succeed 
constitute  the  dorsal  {b  c) ;  and  the  last  five  the  lumbar  region  (c  d). 

There  are  occasionally,  but  very  rarely,  some  variations  in  the 
number  of  vertebrae.  In  a  few  cases  only  six  cervical  vertebrae  have 
been  found  ;  and  Morgagni,  who  first  observed  this  anomaly,  consid- 
ers it  to  be  a  predisposing  cause  of  apoplexy,  on  account  of  the  ac- 
companying shortness  of  the  neck,  and  consequent  approximation 
of  the  heart  and  brain.  There  are  sometimes  thirteen  dorsal  ver- 
tebrae :  sometimes  the  fifth  lumbar  is  united  to  the  first  sacral,  and 
there  are  then  only  four  lumbar  vertebra?.  In  other  cases,  the  first 
sacral  vertebra  is  distinct  from  the  rest,  and  the  lumbar  portion  of  the 
column  then  consists  of  six. 

The  vertebrae  present  general  characters,  which  distinguish  them         / 1^'*^ 
from  all  other  bones :  they  have  also  characters  peculiar  to  each  particular  region ;  and 
in  each  group  or  region  certain  vertebrae  have  individual  distinctive  characters. 

General  Characters  of  the  Vertcbree. 
Every  vertebra  {figs.  2,  3,  4,  5,  6,  7)  is  essentially  asymmet- 
rical ring,  a  segment  of  the  cylinder  which  protects  the  spinal 
marrow,  and  is,  consequently,  perforated  by  a  foramen,  denom- 
inated the  vertebral  or  rachidian  foramen  {I,  fig.  2).  As  it  con- 
curs also  to  form  part  of  a  supporting  column,  it  presents  a  kind 
of  enlargement  or  solid  cylinder,  of  which  the  posterior  fifth 
has  been  removed.  I'his  enlargement  is  the  body  of  the  ver- 
tebra (2).  Each  vertebra  gives  attachment  to  numerous  mus- 
cles, by  very  marked  eminences  for  insertion — the  spinous  (3) 
and  transverse  processes  (4  4).     It  is  articulated  with  the  other 

*  The  same  is  true  of  anchylosis,  as  of  certain  differences  of  form  and  development,  viz.,  that  ihev  lead  t* 
die  establishment  of  varieties,  but  cannot  form  the  ground  of  total  separation. 


Fig.  2. 


20 


OSTEOLOGY. 


vertebrae  by  four  articular  processes  (5  5),  two  superior  and  two  injeriar.  Lastly,  it  pre- 
sents two  superior  and  two  inferior  notches  {7,  Jigs.  4,  5),  which  unite  to  form  the  inter- 
vertebral foramiTia,  through  which  the  vessels  and  nerves  are  transmitted. 

Fig.  3.  A.   The  body  of  the  vertebra  (2)  occupies  the  anterior  portion  of 

/    ,^,    5  the  vertebral  ring,  and  presents /owr  surfaces.     The  superior  and 

"*  ■'"'  inferior  surfaces  are  connected  with  the  contiguous  vertebra,  and 

are  slightly  hollowed  for  the  reception  of  the  intervertebral  sub- 
stance. This  double  excavation  is  the  vestige  of  the  deep  bicon- 
ical  cavity,  so  remarkable  in  the  vertebrae  of  fishes.  The  ante- 
rior  surface  is  convex  transversely,  and  presents  a  horizontal 
^"*'  groove  (2,  Jigs.  4  and  5),  which  is  deeper  laterally  than  in  the  me- 
dian line,  and  in  cases  of  abnormal  curvature  is  greater  on  one  side  than  on  the  other.  This 
groove  is  the  rudiment  of  that  circular  constriction  which  exists  in  the  vertebrae  of  reptUes 
and  fishes,  and  in  the  cervical  vertebrae  of  birds  :  it  has  the  double  advantage  of  economy, 
both  as  to  the  weight  and  the  bulk  of  the  bone.  The  posterior  surface  is  concave,  and 
forms  part  of  the  vertebral  canal.  It  is  pierced  by  numerous  foramina  of  considerable  size, 
which  are  the  orifices  of  venous  canals  hollowed  out  in  the  substance  of  the  vertebra. 
Smaller  foramina  of  the  same  nature  exist  also  on  the  anterior  surface. 

B.  The  vertebral  foramen  {I,  fig.  2)  exhibits  certain  variations  in  form  and  dimensions 
in  the  different  regions  of  the  spine  ;  but  in  nearly  all  the  vertebrae  it  approaches  more 
or  less  to  the  triangular  form.  The  differences  which  it  presents  in  the  extent  of  its 
diameters  bear  reference  partly  to  the  size  of  the  spinal  marrow,  and  partly  to  the  ex- 
tent of  motion  in  each  region. 

C.  The  spinous  process  {3,  figs.  2,  3,  4,  5)  is  that  eminence  of  considerable  size  which 
arises  in  form  of  a  spine  from  the  posterior  part  of  the  vertebral  arch.  It  forms  a  lever 
for  the  extensor  muscles  of  the  trunk,  and  accordingly  varies  in  length,  shape,  and  di- 
rection, in  the  different  regions.  It  bifurcates,  as  it  were,  at  its  base,  and  passes  into  the 
two  lamina  (6  b,  fig.  2),  which  constitute  the  lateral  and  posterior  portions  of  the  arch. 

D.  The  articular  processes  (5  5)  arise  from  the  lateral  portions  of  the  arch  near  its  junc- 
tion with  the  body  of  the  vertebra :  their  direction  is  in  general  vertical,  i.  e.,  perpendicu- 
lar to  the  direction  of  the  articulating  surfaces  of  the  body,  which  are  horizontal.  They 
are  four  in  number,  two  superior  or  ascending,  and  two  inferior  or  descending ;  they  are 
placed  symmetrically  on  each  side  of  the  median  line,  and  are  covered  with  cartilage  in 
the  fresh  state,  to  form  a  movable  joint  with  the  articular  processes  of  the  adjacent 
vertebrae  ;  they  project  beyond  the  level  of  the  bodies  of  the  vertebrae,  so  that  their  artic- 
ulations correspond  with  the  intervertebrtd  substances.  Hence  the  vertebral  column 
presents  two  successive  series  of  articulations  :  one  constituted  in  front,  by  the  union  of 
the  bodies  ;  the  other  behind,  by  the  articular  processes. 

E.  The  transverse  processes  (4  4)  are  lateral  prolongations,  which  arise  from  each  side 
of  the  vertebral  ring,  pass  horizontally  outward,  and  vary  in  length  and  size  in  the  dif- 
ferent regions. 

F.  In  front  of  the  articular  and  transverse  processes,  immediately  behind  and  at  the 
side  of  the  body  of  the  vertebra,  are  four  notches  cut  in  the  lateral  parts  of  the  ring  (7, 
figs.  4  and  5) :  the  inferior  are  generally  deeper  than  the  superior,  but  their  depth  varies 
considerably  in  the  different  regions.  The  part  of  the  vertebral  ring  between  the  upper 
and  lower  notches  is  reduced  to  a  sort  of  pedicle ;  it  is  the  weakest  part  of  the  vertebra, 
and,  consequently,  it  is  the  principal  seat  of  torsion  in  curvatures  of  the  spine.  The  con- 
stituent parts  of  a  vertebra  are,  therefore,  1.  In  the  median  line,  the  body,  the  foramen,  the 
spinous  process,  and  the  lamina ;  2.  On  each  side,  the  articular  and  transverse  processes,  the 
notch,  and  the  pedicle. 

Characters  peculiar  to  the  Vertebra  of  each  Region. 

^^s-  4.  The  characters  distinctive  of  the  vertebrae  of  each  region 

of  the  spine  are  most  marked  in  those  placed  in  the  middle 
of  the  respective  region,  for  at  its  extremes  the  vertebrae 
acquire  intermediate  or  mixed  characters  belonging  to  the 
two  regions  near  the  confines  of  which  they  are  situated.  It 
may  be  remarked,  that  the  vertebrae  of  each  region  may  be 
at  once  recognised  by  Fig.  5. 

one  single  distinctive 
character :  thus,  the  cer- 
vical vertebrae  are  al- 
ways known  by  a  fora- 
men in  the  base  of  the 
transverse  processes  (a, 
fig.  2) ;  the  dorsal  vertebrae  by  facettes  hollowed  out 
on  the  sides  of  the  bodies  (6  6,  fig.  4) ;  and  the  lum- 
bar {fig  5)  by  the  absence  of  the  two  preceding 
•Tnarks."  The  characters  just  mentioned  might,  then,  suffice  as  mere  distinctive  marks,  bu* 


THE    VERTEBRAL,   COLUMN. 


M 


they  woiild  not  answer  the  purposes  of  exact  anatomical  description.  Indeed,  a  vertebra 
is  cervical,  dorsal,  or  lumbar,  rather  in  virtue  of  its  entire  form  and  structure  than  by 
reason  of  any  single  circumstance  pertaining  to  it. 

We  shaU  examine  in  regular  order  each  part  of  a  vertebra,  as  it  exists  in  the  different 
regions. 

Bodies  of  the  Vertebrae  in  different  Regions.  \: 

The  first  distinctive  character  is  their  size.  This  progressively  increases  from  the  cer- 
vical to  the  lumbar  region  (a,  6,  c,  d,fig.  1) :  taking  the  size  of  the  bodies  of  the  lumbiir 
vertebrae  as  unity,  that  of  the  dorsal  would  be  two  thirds,  and  that  of  the  cervical  one  half 

The  second  distinctive  character  is  the  proportion  of  the  diameters.  In  all  vertebrae  the 
transverse  diameter  is  the  greatest,  and  the  vertical  the  smallest.  In  the  lumbar  verte- 
brae the  height  or  vertical  diameter  is  twelve  lines  (one  inch),  in  the  dorsal  nine  lines 
(three  quarters  of-^  inch),  and  in  the  cervical  six  lines  (half  an  inch).  In  the  cervical 
and  lumbar  regions,  the  vertical  diameter  of  the  body  is  less  behind  than  before,  which 
inequality  gives  rise  to  the  anterior  convexity  of  these  regions.  In  the  dorsal  region,  on 
the  other  hand,  the  vertical  diameter  is  shortest  anteriorly.  In  the  lumbar  region,  the 
transverse  diameter  does  not  exceed  the  vertical  and  the  antero-posterior  by  more  than 
one  third  at  most.  In  the  dorsal  region  no  one  diameter  is  strikingly  predominant ;  but 
in  the  cervical  the  transverse  is  almost  double  that  of  the  antero-posterior  and  the  ver- 
tical diameters. 

The  third  distinctive  character  is  formed  by  the  lateral  ridges  of  the  bodies  of  the  cervi- 
cal vertebra.  From  the  two  sides  of  tlip  superior  surface  of  the  bodies  of  the  cervical 
vertebrae  arise  two  small  ridges  {fig.  2,  on  each  side  of  2),  which  are  received  into 
corresponding  depressions  on  the  inferior  surface  of  the  vertebra  above.  This  mutual 
fitting-in  of  the  bodies  of  the  cervical  vertebrae  compensates  for  the  less  secure  connex- 
ion of  their  articular  processes,  and  which  insecurity  is,  moreover,  of  less  importance, 
from  the  bodies  being  united  by  disks  of  intervertebral  substance. 

The  fourth  distinctive  character  consists  in  the  two  demi-facettes  on  each  side  of  the 
bodies  of  the  dorsal  vertebra.  (6  6,  fig.  4).  These  demi-facettes,  when  united  with  the  cor- 
responding parts  of  the  neighbouring  vertebrae,  form  angular  excavations,  in  which  the 
posterior  extremities  of  the  ribs  are  received.  This  character  belongs  exclusively  to  the 
dorsal  vertebrae. 

The  fifth  distinctive  character  is  the  excavation  of  the  superior  and  inferior  surfaces  of 
the  bodies,  which  is  less  in  the  dorsal  region  than  in  the  cervical  or  lumbar.  From  this  dis- 
position it  results,  that  a  lenticular  space  of  a  much  greater  size  intervenes  between 
every  two  of  the  lumbar  and  cervical  vertebrae  than  between  the  dorsal :  the  mobility  is 
consequently  much  increased,  from  the  greater  size  of  the  intervertebral  substance. 

The  specific  characters,  then,  of  the  bodies  of  the  vertebrae  in  the  different  regions  are 
the  following :  1.  Lateral  ridges  on  the  superior  surface  of  the  cervical  vertebra.  2.  Lateral 
facettes  on  the  dorsal  vertebra.  3.  TTie  absence  of  these  two  characters,  and  the  preponder- 
ance of  size  in  the  lumbar  vertebra.  If  the  body  of  a  vertebra  be  presented  for  our  inspec- 
tion, we  can  at  once  determine  from  these  characters  the  region  to  which  it  belongs. 

The  Vertebral  Foramen  and  the  Jfotches  in  the  different  Regions  of  the  Spine. 

The  vertebral  foramen  and  the  notches  present  certain  marked  distinctions  in  the  ver- 
tebrae of  the  three  regions,  by  which  they  may  be  recognised  by  a  practised  eye. 

1.  In  the  cervical  region,  the  transverse  diameter  of  the  foramen  {I,  fig.  2)  considera 
bly  exceeds  the  antero-posterior.  2.  In  the  dorsal  region,  the  two  diameters  are  almost 
equal,  but  there  is  this  much  which  is  remarkable,  that  a  very  considerable  depression 
exists  on  the  posterior  surface  of  the  body  of  the  bone.  3.  In  the  lumbar  region,  the 
transverse  diameter  is  the  greater,  but  the  difference  is  much  less  remarkable  than  in  the 
cervical.  The  following  is  a  comparative  table  of  the  diameters  in  the  three  regions  • 
Transverse  diameter.  Antero-posterior  diameter. 


In  the  neck,  6  lines 
back,  6  lines, 
loins,  8  lines. 


In  the  neck,  1 1  lines, 
back,  7  lines, 
loins,  10  lines. 

It  may  be  remarked  here,  that  these  differences  correspond  with  the  extent  of  motion 
in  each  region.  In  the  lumbar  region,  which  is  more  movable  than  the  dorsal,  the  fora- 
men is  larger ;  and  in  the  cervical  region,  where  the  lateral  motions  are  more  extended 
than  in  the  loins,  the  transverse  diameter  is  still  greater,  in  the  proportion  of  eleven  to 
ten.  It  must  be  observed,  however,  that  the  diameters  of  the  foramen  bear  reference 
not  only  to  the  mobility  of  the  part,  but  also  to  the  size  of  the  spinal  marrow. 

The  notches  present  also  certain  differences  in  the  different  regions ;  thus,  in  the  dor- 
sal and  lumbar  regions  (7,figs.  4  and  5),  the  inferior  are  much  deeper  than  the  superior ; 
in  the  cervical  region  they  are  of  almost  equal  depth  {fig.  3).  It  may  also  be  remarked, 
that  the  depth  of  the  notches,  and,  consequently,  the  size  of  the  intervertebral  foramina. 


82  OSTEOLOGY. 

are  generally  proportional,  not  only  to  the  size  of  the  spinal  ganglions,  but  also  to  tlie 
capacity  of  the  venous  canals,  which  establish  a  communication  between  the  external 
and  internal  veins  of  the  spine.  It  is  then  possible,  when  only  the  vertebral  foramen 
and  the  notches  are  seen,  to  determine  the  region  to  which  the  bone  belongs. 

The  Spinous  Processes  and  Lamincs  in  the  different  Regions. 

1.  In  the  cervical  region,  the  spinous  processes  are  prismatic  and  triangular  {3,  figs.  2, 
3),  grooved  inferiorly  for  the  reception  of  the  spinous  process  of  the  vertebra  below  du- 
ring the  movements  of  extension,  and  bifurcated  at  their  summit,  for  the  purpose  of 
muscular  insertion.  Their  direction  is  horizontal,  and,  consequently,  favourable  to 
extension. 

2.  In  the  dorsal  region  (3,  fig.  4)  they  are  prismatic  and  triangular,  with  a  tubercle  at 
their  summit ;  their  direction  is  extremely  obhque,  approaching  to  the  vertical.  This 
direction,  together  with  their  great  length,  causes  them  to  descen^tfonsiderably  below 
the  inferior  surface  of  the  body  of  the  vertebra.  Hence  a  sort  of  injBncation,  and  to  such 
a  degree  that  a  very  slight  movement  of  extension  causes  them  to  touch  each  other. 

3.  In  the  lumbar  region  the  spinous  processes  (3,  fig.  5)  are  broad,  thick,  and  quadrilat- 
eral, presenting  on  their  sides  a  large  surface  for  muscular  insertion ;  their  posterior 
border  is  thick,  tuberculated,  and  triangular.  Their  direction,  being  horizontal,  presents 
no  obstacle  to  extension. 

The  two  laminae  {b  b,  fig.  2),  which  form  the  posterior  arch  of  the  vertebra,  are  con- 
tinuous with  the  base  of  the  spinous  process.  Their  length  is  directly  proportionate  to 
the  dimensions  of  the  part  of  the  canal  to  which  they  correspond,  and  their  thickness  is 
in  proportion  to  the  size  of  the  spinous  process'. 

1.  In  the  cervical  region  the  laminae  are  thin,  very  long,  and  so  inclined  that  when  the 
head  is  erect,  i.  e.,  in  a  position  intermediate  between  flexion  and  extension,  the  inferior 
edge  of  the  superior  laminae  passes  beyond  the  superior  border  of  the  vertebra  below,  so 
that  there  is  a  true  imbrication  of  these  laminae,  not  less  marked  than  that  which  we 
have  observed  of  the  spinous  processes  in  the  dorsal  region.  There  has  been,  conse- 
quently, no  case  recorded  of  the  entrance  of  any  penetrating  instrument  into  the  spinal 
canal,  in  the  situation  of  the  undermost  five  cervical  vertebrae  ;  which  fact  is  the  more 
easily  conceivable  when  we  reflect  that  the  least  impression  upon  the  back  of  the  neck 
excites,  instinctively,  an  extension  of  the  head,  and  thus  increases  the  imbrication  of 
the  laminae.  2.  In  the  dorsal  region  the  thickness  of  the  laminae  is  greater  than  in  the 
neck,  but  still  inferior  to  that  in  the  loins  ;  they  are  comparatively  much  shorter  than  in 
the  cervical  region,  and,  instead  of  forming  an  elongated  rectangle,  they  represent  a 
square — nay,  their  vertical  dimension  almost  exceeds  the  transverse.  3.  In  the  lumbar 
region  they  are  characterized  by  great  thickness,  by  diminution  of  the  transverse,  and 
marked  increase  of  tlie  vertical  diameter.  In  general,  it  may  be  stated  that  the  height 
of  the  lamina  corresponds  with  the  thickness  of  the  body  of  the  vertebra  to  which  it  be- 
longs ;  hence  they  are  so  narrow  in  the  cervical  region. 

To  sum  up,  then,  the  characters  of  the  spinous  processes  and  the  laminae : 

1.  Cervical  Region. — Processes  prismatic  and  triangular,  grooved  inferiorly,  bifurcated 
with  two  tubercles  at  their  summit,  horizontal,  short,  and  continuous,  with  long,  narrow,  and 
thin  lamina,,  inclined  so  as  to  become  imbricated.  2.  Dorsal  Region. — Spinous  processes 
prismatic  and  triangular,  long,  oblique,  and  tuberculated  at  their  summit,  with  short  vertical 
laminae.  3.  Lumbar  Region. — Spinous  processes  quadrilateral,  strong,  and  horizontal,  with 
very  sJiort,  thick,  and  vertical  lamina.  It  is  possible,  then,  from  the  spinous  process  and 
its  laminae  alone,  to  determine  the  region  of  any  vertebra. 

The  Articular  Processes  in  the  different  Regions. 

In  the  cervical  region  (5  5,  figs.  2  and  3)  the  articular  processes  form  small  columns, 
and  are  so  directed  that  their  articular  siu'face  makes,  with  the  horizon,  an  angle  of 
about  45°  ;  the  superior  look  upward  and  backward,  the  inferior  downward  and  forward. 
It  is  important  to  remark  this  direction,  because  it  permits  the  movements  of  flexion, 
extension,  and  lateral  inclination :  it  is  owing  to  the  same  circumstance,  also,  that  lux- 
ations of  the  cervical  vertebrae  may  occur  without  fracture  of  their  articular  processes. 
It  should  be  also  observed  that  the  articular  surfaces  of  the  right  and  left  sides  are  in 
the  same  plane. 

2.  In  the  dorsal  region  (5  5,  fig.  4)  the  articular  processes  are  simple  laminae,  the  di 
rection  of  which  is  vertical  and  the  surface  plane.  The  superior  look  backward  and  out- 
ward, the  inferior  forward  and  inward.  The  articular  facette  of  the  right  side  is  not  on 
the  same  plane  as  that  of  the  left. 

I  should  observe  that,  in  certain  cases,  the  dorsal  articular  processes  are  found,  as  it 
were,  locked  together,  the  extremity  of  the  superior  process  being  received  into  a  deep 
notch  on  the  surface  of  the  inferior  process  of  the  vertebra  above. 

3.  In  the  lumbar  region  (5  5,  fig.  5)  the  articular  processes  are  very  strong,  with  curved 


THE    VERTEBRAL   COLUMN.  23 

surfaces.  The  superior  concave  look  backward  and  inward,  the  inferior  convex  forward 
and  outward.  They  both  represent  two  segments  of  a  cyhnder,  one  of  which  complete- 
ly surrounds  the  other,  or,  rather,  the  inferior  resemble  half  hinges,  which  are  received 
into  the  half  rings  formed  by  the  superior  processes.  It  should  be  observed  here,  that 
the  superior  articular  processes  are  prolonged  by  certain  tubercles,  to  which  the  name 
of  ajpophysary  may  be  correctly  appUed,  and  which  serve  for  the  insertion  of  muscles. 
To  sum  up,  then,  what  has  been  said :  The  cervical  articular  processes  are  small  columns, 
cut  with  plane  faces,  at  an  inclijiation  of  45°,  those  of  both  sides  on  the  same  plane ;  the  dor- 
sal are  thin  lamina,  plane  and  vertical,  but  not  in  the  same  plane ;  the  lunibar  strong,  vertical, 
and  tuicrculated  lamincz,  with  a  curved  articular  surface.  The  region  of  any  given  verte- 
bra may  be  easily  recognised  from  its  articular  processes  alone. 

The  Transverse  Processes  in  the  different  Regions  of  the  Spine. 

No  part  of  the  vertebrae  presents  more  decided  variations  in  the  different  regions  than 
the  transverse  processes. 

1.  In  the  cervical  region  (4  i,Jigs.  2  and  3)  they  are  grooved  superiorly  for  the  lodg- 
ment of  the  anterior  branches  of  the  cervical  nerves  ;  their  base  is  perforated  {a,  fig.  2) 
for  the  passage  of  the  vertebral  artery ;  they  have  two  borders,  an  anterior  and  posterior, 
to  which  the  inter-transversal  muscles  are  attached ;  their  free  extremity  is  bifurcated 
for  the  attachment  of  muscles.  It  should  be  added,  that  these  transverse  processes,  be- 
ing on  the  same  plane  with  the  bodies  of  the  vertebrae,  double  their  transverse  diameter 
in  front,  and  enable  them  to  afford  support  to  a  great  number  of  parts. 

2.  In  the  dorsal  region  (4,  fig.  4)  they  are  large  and  horizontal,  much  stronger  than  in 
the  other  regions,  and  twice  or  three  times  the  size  of  the  spinous  processes ;  they  are 
much  incUned  backward,  and  the  anterior  surface  of  their  extremity  has  a  depression 
for  articulation  with  the  tubercle  of  the  ribs.  Some  anatomists  have  attached  great  im- 
portance to  the  direction  of  the  articular  facettes,  making  it  the  basis  of  their  notions  of 
the  mechanism  of  respiration.  The  important  modifications  which  the  transverse  pro- 
cesses of  the  dorsal  vertebrae  present  are  evidently  connected  vdth  the  nature  of  their 
functions,  which  are  not  only  that  of  affording  points  of  insertion  to  muscles,  but  also  of 
supporting  the  ribs  with  which  they  are  articulated. 

3.  In  the  lumbar  region,  the  transverse  processes  (4,  fig.  5)  are  thin,  narrow  laminae, 
flattened  from  before  backward.  They  are  situated  in  a  plane  anterior  to  that  which  the 
transverse  processes  of  the  dorsal  vertebrae  occupy,  and  almost  correspond  with  that  of 
the  ribs,  with  which,  also,  they  have  numerous  other  analogies  :  hence  the  name  costi- 
form  processes  given  them  by  some  anatomists.*  The  characteristics,  then,  of  the  three 
kinds  of  transverse  process  are,  in  the  cervical  region,  a  grooved  projection  with  a  foramen 
at  the  base  ;  in  the  dorsal  region,  a  strong  process  inclined  backward,  tuberculated,  and  artic- 
ular at  the  extremity  ;  in  the  lumbar  region,  a  small,  thin,  blunted  projection.  It  is,  therefore, 
extremely  easy  to  determine  the  situation  of  a  vertebra  by  the  transverse  process. 

The  truth  of  what  we  formerly  remarked  will  be  now  evident,  viz.,  that  a  vertebra  is 
distinguished  as  cervical,  dorsal,  or  lumbar,  by  the  form  of  all  its  constituent  parts.  Uni- 
form in  their  fundamental  type,  these  bones  present,  in  each  region,  and  in  each  part, 
certain  differences  adapted  to  their  respective  uses. 

Characters  proper  to  certain  Vertebras. 

We  have  now  noticed,  1 .  The  general  characteristics  of  the  vertebrae,  by  means  of 
which  they  may  be  recognised  from  all  other  bones ;  2.  The  peculiar  distinguishing 
chraracters  of  the  vertebrae  in  each  region.  We  have  now  to  examine  in  each  region 
those  vertebrae  which  are  distinct  from  all  the  others  of  that  part  of  the  spine.  The 
place  of  each  vertebra  might,  strictly  speaking,  be  determined  by  comparing  it  with  all 
the  other  vertebrae  of  the  same  region :  in  this  way,  those  who  are  accustomed  to  artic- 
ulate skeletons  acquire  surprising  readiness.  But  a  few  vertebrae  only  possess  suffi- 
ciently characteristic  peculiarities  to  determine  their  situations  without  comparison  with 
the  others.  It  is  only  in  the  vertebrae  at  the  extremity  of  each  region,  and  which,  on 
account  of  their  position,  have  a  mixed  character,  that  such  distinctive'and  individual 
attributes  can  be  observed. 

The  first,  second,  and  seventh  cervical  vertebrae,  the  first,  eleventh,  and  twelfth  dor- 
sal, and  the  fifth  lumbar,  require  special  description. 

First  Cervical  Vertebra,  or  Atlas  (jig.  6). 
In  the  first  vertebra,  or  atlas,  the  place  of  the  body  is  supplied  by  an  arch  (a  g),  flattened 

*  The  description  which  we  have  given  of  the  transverse  processes  is  in  accordance  with  that  usually  foniLd 
m  works  on  human  anatomy.  Several  modern  anatomists,  however,  do  not  admit  of  the  arrangement  which 
we  have  adopted.  From  the  existence  of  cervical  and  lumbar  ribs  in  the  skeletons  of  many  vertebrated  ani- 
mals, they  maintain  that  in  man  the  anterior  half  of  the  cervical  transverse  processes,  and  the  thin  plates  of  the 
lumbar  transverse  processes,  represent  the  ribs  of  the  dorsal  region  ;  while  the  parts  truly  analogous  to  the 
dorsal  transverse  processes  are,  1.  In  the  cervical  region,  the  posterior  half  of  the  transverse  process ;  2.  lo 
the  lumbar  region,  those  projections  which  we  have  called  apophysary  tubercles. 


^  .      -  OSTEOLOGY. 

j^    g  from  before  backward,  the  wtaerior  arch  of  the  first  verU' 

a    '  Irra.     Its  convexity,  turned  forward,  is  marked  by  a  tu- 

bercle (a),  the  anterior  tubercle  of  the  atlas.  Its  concav- 
ity, looking  backward,  presents  an  oval  facette,  slightly 
hollowed  for  articulation  with  the  odontoid  process  of 
the  second  vertebra.  The  superior  and  inferior  borders 
afford  attachment  to  ligaments. 

The  foramen  of  the  first  vertebra  is  much  larger  than 
that  of  all  the  others.     The  antero-posterior  diameter, 
^  which  in  the  neck  and  back  is  six  lines,  and  in  the  loins 

eight,  is  here  fourteen ;  the  transverse  diameter,  eleven  lines  in  the  neck,  seven  in  the 
back,  and  ten  in  the  loins,  is  here  thirteen.  This  remarkable  extent  of  aU  the  diameters 
is  not  simply  owing  to  the  size  of  the  spinal  marrow  at  this  point,  for  the  anterior  por- 
tion of  the  foramen  (/,  ^, /)  gives  lodgment  to  the  odontoid  process  of  the  second  verte- 
bra, so  that  the  antero-posterior  diameter  of  the  part  which  contains  the  spinal  cord  does 
not  greatly  exceed  that  of  the  foramen  in  the  succeeding  vertebrae.  The  transverse  di- 
ameter alone  is  more  considerable,  whence  the  possibility  of  lateral  displacements  or 
incomplete  luxations  of  the  first  upon  the  second  vertebra  without  any  marked  com- 
pression of  the  cord. 

The  notches  (A  h)  are  situated  on  the  posterior  arch  at  its  junction  with  the  lateral 
masses.  They  are  posterior  to  the  articular  processes,  while  in  aU  the  other  vertebrae 
they  are  anterior.  The  superior  are  very  deep,  often  converted  into  foramina  by  a 
bridge  of  bone,  and  seem  to  be  continuous  with  the  foramen  in  the  base  of  the  trans- 
verse process,  by  means  of  a  horizontal  groove  which  winds  round  behind  the  articular 
process.  This  groove  is  sometimes  almost  converted  into  a  complete  canal.  From  the 
union  of  these  parts,  viz.,  the  notch,  groove,  and  foramen,  a  twisted  canal  results,  verti- 
cal at  first,  and  afterward  horizontal,  along  which  the  vertebral  artery  runs  in  its  pas- 
sage into  the  cranium.  Through  the  superior  notch,  which  almost  forms  by  itself  the 
.first  intervertebral  foramen,  the  vertebral  artery  and  vein  and  the  first  cervical  nerve 
pass.  The  inferior  notches  present  nothing  remarkable,  excepting  that  they  are  sufi5- 
ciently  deep  to  form,  by  themselves,  the  intervertebral  foramina  between  the  first  and 
second  vertebrae. 

There  is  no  spinous  process :  its  place  is  supplied  by  a  posterior  tubercle  (i)  for  muscu- 
lar insertion,  analogous  to  the  anterior  tubercle,  or,  more  correctly,  resembling  a  spinous 
process  truncated.  Sometimes,  instead  of  a  tubercle,  there  are  only  some  inequalities. 
The  posterior  arch  (A,  i,  h),  which  forms  more  than  half  the  circumference  of  the  verte- 
bra, consists  of  two  strong  and  long  plates. 

The  articular  processes  or  columns,  which  we  have  remarked  throughout  the  whole  cer- 
vical region,  are  very  large  in  the  atlas,  and  bear  the  name  of  lateral  masses.  This  struc- 
ture is  connected  with  the  use  of  the  bone,  which  is  to  support  the  occipital  condyles, 
and,  consequently,  the  weight  of  the  head. 

Of  the  four  articular  processes,  the  superior  (J  b)  are  concave,  slanting  inward,  oval, 
and  obliquely  directed  from  behind  forward,  and  from  without  inward.  Their  form  ex- 
actly corresponds  with  the  convexity  of  the  occipital  condyles  (7  7,  fig.  10),  which  they 
receive,  and  for  this  purpose  their  external  borders  and  posterior  extremities  are  con- 
siderably elevated.  Within  and  below  the  articular  surface  are  certain  inequalities 
(//,  fig.  6),  which  give  attachment  to  the  transverse  ligament.  The  inferior  articular 
processes  are  circular  and  plain ;  they  look  downward  and  a  little  inward. 

The  transverse  processes  (c  c)  are  very  large  and  triangular :  they  have  only  one  tuber- 
cle, into  which  are  inserted  the  principal  rotatory  muscles  of  the  head :  they  are  per- 
forated by  a  foramen  (e)  at  the  base,  but  are  not  grooved  on  their  surface. 

The  characteristics,  then,  of  the  atlas  are,  a7i  annular  form  ;  great  lateral  dimensions, 
so  that  it  surmounts  the  vertebral  column  like  a  capital ;  a  very  large  vertebral  foramen ;  no 
body,  nor  spinous  process  ;  large  lateral  masses,  supporting  very  strong  transverse  processes, 
which  are  not  grooved,  and  have  only  one  tubercle. 

Second  Vertebra,  ^xis,  or  Vertebra  Dentata  {Jig.  7,  side  view). 
The  body  is  surmounted  by  an  eminence  {g,  a,  I,  fig.  7),  "Which,  in  the  connected  skel- 
pig_  7_  eton,  corresponds  with  the  anterior  arch  of  the  atlas.     This  em- 

inence has  received  the  name  odontoid  process,  or  processus  den- 
tatus,  from  its  tooth-like  form.  It  constitutes  a  species  of  cylin- 
drical pivot,  about  half  an  inch  in  length,  round  which  the  head 
turns ;  and  hence  the  name  axis  given  to  the  entire  vertebra. 
It  is  attached  to  the  body  of  the  bone  by  a  broad  basis,  is  then 
constricted,  and  terminates  superiorly  in  an  enlargement  called 
the  head,  which  is  rough  at  its  summit  (a),  and  gives  attachment 
[^i  to  the  odontoid  ligaments.  The  contracted  portion  (l)  is  called 
the  neck ;  it  is  the  weakest  part  of  the  process,  and  is,  conse- 
quently, the  invEiriable  seat  of  its  fractures.    This  circular  cob- 


THE    VERTEBRAL   COLUMN.  25 

striction  of  the  inferior  part  of  the  odontoid  process  contributes  to  maintain  it  in  the 
semi-osseous,  semi-ligamentous  ring  in  which  it  turns.  Two  articular  facettes  are  seen 
on  this  process  :  one  in  front  {g),  corresponding  with  the  anterior  arch  of  the  atlas  ;  the 
other  behind  (at  /),  for  the  transverse  Ugament. 

The  body  (c)  of  the  axis  presents  anteriorly  a  triangular  vertical  ridge,  which  separ- 
ates two  lateral  depressions  for  the  attachment  of  muscles.  The  posterior  surface  cor- 
responds with  the  vertebral  canal.  The  greatest  diameter  of  the  inferior  surface  is  the 
antero-posterior  :  it  is  obliquely  sloped  downward  and  forward,  and  slightly  concave,  for 
the  reception  of  the  body  of  the  third  cervical  vertebra.  This  mutual  reception  of  the 
two  bones  does  not  take  place  between  any  of  the  succeeding  vertebrae. 

The  foramen  is  shaped  like  the  figure  of  a  heart  on  playing  cards  :  its  antero-posterior 
diameter  is  eight  lines,  which  is  two  lines  more  than  in  the  other  cervical  vertebrae,  and 
its  transverse  diameter  is  the  same.  This  great  size  of  the  foramen  of  the  second  ver- 
tebra corresponds  with  the  extent  of  the  movements  between  it  and  the  atlas. 

There  is  no  superior  notch,  the  inferior  notch  of  the  atlas  forming  by  itself  the  inter- 
vertebral foramen.     The  inferior  notch  presents  nothing  peculiar. 

The  spinous  process  {k,  m),  though  of  great  length,  is  even  more  remarkable  for  its 
breadth  and  thickness,  presenting,  as  it  were,  in  an  exeiggerated  degree,  the  characters 
of  the  cervical  spinous  processes :  its  form  is  prismatic  and  triangular ;  it  is  grooved 
inferiorly,  and  terminates  by  two  tubercles  for  the  attachment  of  powerful  muscles.  The 
spinous  process  is  for  the  axis  that  which  the  transverse  process  is  for  the  atlas,  both 
giving  insertion  to  powerful  muscles,  which  move  the  head  upon  the  vertebral  column. 

The  lamina,  which  correspond,  as  usual,  with  the  size  of  the  spinous  process,  are  re- 
markably strong. 

The  superior  articular  processes  {d)  are  placed  on  each  side  of  the  body.  Their  facettes 
are  broad,  flat,  and  almost  horizontal,  being  slightly  inclined  outward.  This  direction 
permits  the  atlanto-axoidean  articulation  to  be  the  centre  of  all  the  rotatory  movements 
of  the  head. 

The  inferior  articular  processes  (e)  resemble  those  of  the  other  cervical  vertebrae. 

The  transverse  processes  («)  are  small,  with  only  one  tubercle,  triangular,  bent  down- 
ward, and  perforated  at  the  base  by  a  foramen  (/),  or,  rather,  a  bent  canal,  which  is  hol- 
lowed out  on  each  side  of  the  body  of  the  bone ;  and  is  verticed  in  the  first  part  of  its 
course,  then  horizontal.  This  canal,  and  that  which  we  have  described  upon  the  atlas, 
mark  the  winding  course  of  the  vertebral  artery  before  it  enters  the  cranium. 

The  specific  characteristics,  then,  of  the  second  vertebra  are,  the  odontoid  process,  the 
great  size  of  the  spinous  process  and  the  lamince,  the  large  size  and  horizontal  direction  of 
the  superior  articular  processes,  which  are  placed  on  each  side  of  the  body,  and  the  shortness 
of  the  transverse  processes,  which  are  triangular,  and  have  one  tubercle. 

Seventh  Cervical  Vertebra,  or  Vertebra  Prominens  (6,  fig.  1). 

The  body  has  the  ordinary  characters  observed  in  the  cervical  vertebrae,  but  in  size  it 
resembles  that  of  the  dorsal  vertebrae,  and  frequently  presents  laterally  a  small  impres- 
sion for  articulation  with  the  head  of  the  first  rib.  The  spinous  process  bears  the  greatest 
resemblance  to  those  of  the  dorsal  vertebrae  :  it  is  pyramidal,  terminates  in  a  single  tu- 
bercle, and  is  of  great  length,  projecting  considerably  beyond  the  level  of  the  other  cervi- 
cal vertebras ;  hence  its  name  of  vertebra  prominens.  The  articular  processes  are  almost 
vertical,  and  are  not  supported  by  small  columns.  The  transverse  process,  although  groov- 
ed and  perforated  at  the  beise,  as  in  all  the  other  cervical  vertebra,  closely  approaches 
to  the  characters  of  the  dorsal.  The  posterior  border  of  the  groove,  or  posterior  root  of 
the  process,  is  thick,  tub-^rcular,  and  exactly  similar  to  a  dorsal  transverse  process,  while 
the  anterior  is  thin  and  idimentary,  excepting  in  cases  where  it  is  separated  from  the 
body  of  the  bone,  and  fonns  a  supernumerary  rib.  *  The  foramen  in  the  base  of  the  trans- 
verse process  is  very  rarely  absent,  but  is  most  commonly  small :  in  one  case  only  I  have 
found  it  double.    It  is  never  traversed  by  the  vertebral  artery. 

First  Dorsal  Vertebra. 

This  vertebra  resembles  the  cervical,  in  having  its  body  surmounted  laterally  by  two 
hook-like  processes  or  ridges,  but,  in  all  other  respects,  it  is  strictly  analogous  to  the 
other  dorsal  vertebrae.  It  should  be  also  observed,  that  the  body  presents  an  entire 
facette  for  the  first  rib,  and  a  third  or  fourth  part  of  another  for  the  second. 

Eleventh  and  Twelfth  Dorsal  Vertebrce. 

The  eleventh  dorsal  vertebra  presents  on  each  side  of  the  body  an  entire  facette  for  the 
eleventh  rib.  Its  body  is  very  large,  and  the  place  of  the  transverse  process  is  supplied 
by  a  tubercle. 

The  twelfth  dorsal  vertebra  (c,  fig:  1)  resembles  the  lumbar  in  its  body,  which  is  scarcely 

*  This  circumstance  is  one  of  the  facts  appealed  to  with  most  success  by  those  who  make  the  distinction  of 
transverse  and  costiform  processes. 

D 


go  OSTEOLOGY. 

smaller  than  that  of  the  lumbar  vertebrae,  and  of  which  the  transverse  diameter  begins 
to  predominate.  The  spinous  process  is  horizontal,  strong,  and  quadrilateral.  The 
transverse  processes  are  represented  by  tubercles,  which,  like  those  of  the  preceding 
bone,  are  evidently  continued  in  the  lumbar  region  by  those  tubercles  which  we  have 
denominated  apophysary.  Lastly,  the  body  presents  entire  articular  facettes.  It  ia 
distinguished  from  the  eleventh  dorsal  vertebra  by  the  curved  surface  of  the  inferior 
articular  processes. 

Fifth  Lumbar  Vertebra. 

The  inferior  surface  of  the  body  slopes  very  obliquely  dowTiward  and  forward.  The 
transverse  processes  vary  in  size,  but  are  generally  much  larger  than  those  of  the  other 
lumbar  vertebrae ;  the  inferior  articular  processes,  which  are  farther  separated  fix)m  each 
other,  have  a  flat  surface,  and  look  directly  forward. 

These  are  the  only  vertebrae  which  in  each  region  present  peculiarities.  Excepting 
the  first  and  second  cervical,  which  have  many  characters  quite  foreign  to  the  vertebrae 
of  the  region  to  which  they  belong,  it  might  be  said  of  those  peculiar  vertebrae  which 
have  been  specially  described,  that  their  peculiarities  are  comprehended  in  the  general 
statement  that  those  vertebrae  which  are  placed  at  the  limits  of  any  two  regions  possess 
characters  belonging  to  both  regions. 

Vertebra  of  the  Sacro-coccygeal  Region. 

AU  the  vertebrae  of  this  region,  nine  in  number,  are  in  the  adult  state  united  into  two 
bones  :  the  five  superior  form  the  sacrum,  the  four  inferior  the  coccyx. 

The  Sacrum  (rf,  e^figs.  1  and  8). 

The  scxrum  has  received  its  name  from  the  alleged  practice  of  the  ancients  of  ofFering 
this  part  of  the  victim  in  sacrifice.  It  occupies  the  posterior  and  median  part  of  the 
pelvis,  behind  the  point  where  this  cavity  articulates  with  the  thigh  bone,  an  arrange- 
ment advantageous  for  the  erect  position.  It  is  inserted,  like  a  wedge,  between  the  two 
haunch  bones.  Above,  it  corresponds  with  the  true  vertebral  column ;  below,  with  the 
coccyx.  It  is  directed  obliquely  backward  and  downward  ;  hence  the  column  represent- 
ed by  the  sacrum  forms  an  obtuse  angle  with  the  lumbar  column,  the  projection  of  which  is 
anterior.  This  angle  is  denominated  the  promontory,  or  the  sacro-vertebral  angle  {d,  fig.  1 ) : 
it  is  an  important  object  of  study,  both  with  reference  to  the  mechanism  of  standing,  and 
in  the  practice  of  midwifery.*  The  sacrum  is  curved  upon  itself,  from  behind  forward, 
so  as  to  present  an  anterior  concavity.  It  is  the  largest  of  all  the  bones  of  the  vertebral 
column ;  hence  the  name  of  great  vertebra  applied  to  it  by  Hippocrates.  It  is  proportion- 
ally more  developed  in  man  than  in  any  other  mammiferous  animal,  which  is  connected 
with  the  erect  bipedal  attitude  and  the  sitting  attitude  which  belong  to  him  in  a  special 
manner,  t  The  form  of  the  sacrum  is  that  of  a  quadrangular  pyramid  with  a  truncated 
apex,  the  base  looking  upward.  It  is  symmetrical,  like  all  the  median  bones,  and  pre- 
sents for  consideration  an  anterior,  a  posterior,  and  two  lateral  surfaces,  a  base,  and  a  summit. 
The  anterior,  pelvic,  or  rectal  surface  {fig.  8)  forms  part  of  the  cavity  of  the  pelvis.  Its 
Pig_  8.  concavity  varies  much  in  different  individuals,  and  in  the  two  sex- 

es :  but  on  this  latter  point  there  is  great  diversity  of  opinion  among 
anatomists.  Some  believe  that  it  is  greater  in  the  female,  whence, 
it  is  said,  results  the  advantage  of  a  larger  capacity  of  the  pelvis, 
and,  consequently,  an  increased  facility  for  the  passage  of  the  head 
of  the  fcetus  during  parturition.  Others,  on  the  contrary,  contend 
that  the  male  sacrum  is  more  curved,  and  that  of  the  female  al- 
most straight ;  and  they  argue  that,  had  the  opposite  been  the  case, 
the  coccyx,  which  forms  a  continuation  of  the  curve  of  the  sacrum, 
would  have  been  directed  forward,  and  thus  diminished  the  ante- 
ro-posterior  diameter  of  the  outlet  of  the  pelvis ;  whereas,  with  a 
slight  curve  of  the  sacrum,  the  coccyx  has  no  tendency  to  project, 
but  is  easily  bent  backward  during  labour.  J 

In  order  to  determine  the  validity  of  these  opposing  statements, 
I  have  compared  a  great  number  of  sacra  from  both  sexes,  but  I 
could  never  detect  any  difference  sufficiently  marked  or  constant  to  be  considered  as 
characteristic  of  the  sex. 

*  The  sacro-vertebral  angle  is  most  remarkable  in  man,  because  he  alone  is  destined  for  the  erect  posture. 
By  this  angle  the  impetus  of  movement  transmitted  from  the  vertebral  column  to  the  sacrum  is  in  part  de- 
stroyed.   In  midwifery  it  explains  the  rarity  of  median  positions  of  the  vertei 

t  Birds,  -which,  like  man,  are  biped,  are  also  remarkable  for  the  size  of  their  sacrum. 

t  A  very  great  curvature  of  the  sacrum  diminishes  not  only  the  antero-posterior  diameter  of  the  inferior, 
but  also  that  of  the  superior  aperture  of  the  pelvis  ;  and  it  thus  opposes  the  ascent  of  the  uterus  from  the  true 
into  the  false  pelvis.  Accouclieurs  cannot  too  carefully  study  the  varieties  presented  by  the  curvature  of  this 
bone.  The  sacrum  is  often  affected  by  a  species  of  rickets,  vrhen  the  other  bones  of  the  pelvis  are  free  from 
deformity ;  and  this  fact  may  be  easily  explained  by  a  reference  to  the  uses  of  this  bone  in  suf  Dorting  the 
whole  weight  of  the  trunk. 


THE    VEETEBRAL   COLUMN.  27 

The  anterior  concavity  of  the  sacrum  is  interrupted  by  four  transverse  projections  (1 
1  1  l,Jig.  8),  which  correspond  vi^ith  the  points  of  union  of  the  sacral  vertebrae,  and  are 
analogous  to  the  intervertebral  prominences.  The  first  is  sometimes  so  prominent,  that 
it  might  be  mistaken  for  the  sacro-vertebral  angle  in  an  examination  per  vaginam. 

On  each  side  of  the  median  line  are  the  anterior  sacral  foramina  (2  2  2),  four  in  number, 
the  two  superior  much  greater  than  the  two  inferior.  They  give  passage  to  the  anteri- 
or branches  of  the  sacral  nerves,  to  the  sacral  veins,  and  some  small  arteries.  External 
to  these  are  grooves  for  the  nerves,  and  the  attachment  of  the  pyramidalis  muscle.  The 
anterior  surface  of  the  sacrum  is  contiguous  to  the  rectum,  which  follows  its  curvature. 
Posterior,  spinal,  or  cutaneous  surface.  Its  convexity  is  exactly  proportioned  to  the  an- 
terior concavity.  1.  In  the  median  line  it  presents  the  sacral  ridge,  formed  by  a  continu- 
ation of  the  spinous  processes  of  the  vertebral  column.  This  is  often  entire  in  its  whole 
length,  but  sometimes  interrupted :  it  bifurcates  inferiorly,  and  fonns  the  borders  of  the 
groove  which  terminates  the  sacral  canal.  The  sacral  ridge  is  rarely  found  cleft  through- 
out its  whole  length. 

2.  On  each  side  of  the  median  line  are  two  shallow  grooves,  named  the  sacral  grooves  : 
they  are  continuations  of  the  vertebral  grooves  ;  they  are  pierced  by  four  posterior  saeral 
foramina,  smaller  than  the  anterior  foramina,  and  differing  less  from  each  other  in  di£un- 
eter.  These  afford  passage  to  the  posterior  branches  of  the  sacral  nerves,  to  some  veins 
and  arteries.  They  are  bordered  by  two  ranges  of  unequal  projections  :  the  first  row, 
placed  interior  to  the  foramina,  represent  the  articular  processes  united  together ;  the 
second,  external  to  the  foramina,  are  more  marked,  and  correspond  with  the  transverse 
processes  also  united. 

The  lateral  surfaces  {d,  e,fig.  1)  are  triangular,  broad  above,  narrow  below,  where  they 
constitute  mere  borders.  They  slope  obliquely  from  before  backward  and  from  without 
inward,  so  that  the  sacrum  is  wedged  between  the  haunch  bones  in  an  antero-posterior 
as  well  as  in  a  vertical  direction.  In  front  is  a  demi-oval  or  crescentic  surface  (7,  fig. 
8),  compared  from  its  shape  to  the  human  ear,  and  hence  denominated  auricular  surface. 
In  the  fresh  state  it  is  covered  with  cartilage,  and  articulates  with  the  os  innominatum. 
Behind  it  is  a  very  rugged  surface  with  irregular  depressions,  giving  attachment  to  the 
posterior  sacro-ihac  hgaments.  The  sinuous  border  which  terminates  each  lateral  sur- 
face inferiorly  gives  attaclunent  to  the  sacro-sciatic  ligaments. 

The  hose  presents,  1.  In  the  middle  an  oval  facette  (3,^^.  8),  in  all  respects  similar  to 
the  body  of  a  lumbar  vertebra,  with  the  last  of  which  bones  it  is  articulated.  Behind 
this  is  a  triangular  aperture  resembling  the  foramen  of  other  vertebrae,  and  completed 
posteriorly  by  two  lamince,  which  unite,  and  form  a  spinous  process,*  the  commencement 
of  the  sacral  ridge.  2.  On  each  side  two  triangular  surfaces  (4  4),  smooth,  looking  for- 
ward and  upward,  and  constituting  part  of  the  greater  or  false  pelvis.  They  are  separ- 
ated from  the  anterior  surface  of  the  sacrum  by  a  blunt  edge,  which  forms,  as  we  shall 
afterward  see,  a  portion  of  the  superior  aperture  of  the  pelvis.  Behind  the  oval  surface 
of  the  body  are  notches,  which  complete  the  last  intervertebral  foramina ;  and  behind  these 
notches  are  the  articular  processes  (5  5),  which  resemble  the  superior  articular  processes 
of  the  fifth  lumbar  vertebra,  and  receive  the  inferior  processes  of  that  bone. 

The  apex  (6)  is  truncated,  and  presents  a  transverse  elliptical  surface,  which  articu- 
lates with  the  base  of  the  coccyx.  Behind  it  is  the  termination  of  the  sacral  groove, 
bounded  by  two  small  apophyses,  intended  to  unite  with  two  similar  projections  of  the 
coccjrx.     These  are  the  sthoII  cornua  of  the  sacrum. 

The  sacral  canal.  The  termination  of  the  vertebral  canal  is  prismatic  and  triangular, 
wide  superiorly,  contracted  and  flattened  inferiorly,  where  it  degenerates  into  ar  groove, 
which  is  converted  into  a  canal  by  ligaments.  This  canal  lodges  the  sacral  nerves,  and 
communicates  both  with  the  anterior  and  posterior  sacral  foramina. 

The  Coccyx  (8,  9,  jig.  8). 

This  consists  of  four,  rarely  of  five,  pieces  of  bone  :  they  are  flattened  from  before 
backward,  and  diminish  successively  in  size  from  the  first  to  the  last :  they  are  common- 
ly united  together,  rarely  separate,  the  largest  corresponding  with  the  apex  of  the  sa 
crum ;  the  smallest  is  a  mere  nodule  of  bone,  generally  unattached.  The  wh«le  knot- 
ted-like  bone,  thus  constituted,  has  a  triangular  shape,  and  follows  the  direction  of  the 
lower  part  of  the  sacrum.  It  may  be  regarded  as  the  rudiment  of  the  tails  of  the  lower 
animals.  In  some  cases  I  have  seen  it  form  a  right  angle,  or  even  an  acute  angle  with 
the  sacrum. 

1 .  The  posterior,  spinal,  or  cutaneous  surface,  is  rough,  for  the  insertion  of  the  aponeuro- 
sis of  the  gluteus  maximus. 

2.  The  anterior  surface  resembles  the  same  part  of  the  sacrum  in  miniature,  and,  like 
it,  is  in  immediate  proximity  to  the  rectum. 

3.  The  borders  are  narrow,  sinuous,  and  tubercular,  and  give  attachment  to  the  sacro* 
sciatic  ligaments. 

*  I  have  seen  this  spinous  process  completely  bifurcated. 


W8  '='■*■       OSTEOLOGY. 

4.  The  base  is  often  united  by  bone  to  the  sacrum,  even  in  young  subjects ;  it  pre- 
sents an  elliptical  articular  surface,  exactly  corresponding  with  that  on  the  lower  end  of 
the  sacrun  .  Behind  are  two  processes  directed  upward  (cornua  of  the  cocc3rx,  8  8,  fig. 
8),  which  are  sometimes  continuous  with  the  small  cornua  of  the  sacrum.  ExternaUy 
are  two  notches,  which  are  converted  into  foramina  by  means  of  ligaments,  and  afford 
passage  to  the  fifth  pair  of  sacral  nerves. 

5.  The  apex  (9),  which  is  sometimes  enlarged  and  sometimes  bifurcated,  gives  attach 
ment  to  the  levator  ani  muscle.  It  is  not  uncommon  to  find  the  last  pieces  of  the  coc- 
cyx deviating  from  the  median  line. 

Of  the  Vertebral  Column  in  general. 

Having  already  described  the  situation  of  the  vertebral  column,  we  shall  now  consid- 
er its  dimensions  as  an  entire  piece  of  the  skeleton. 

Dimensions  of  the  Vertebral  Column. 

1.  The  length  or  height  of  the  vertebral  column  does  not  correspond  with  the  length  ol 
the  spinal  marrow,  which  does  not  extend  below  the  first  lumbar  vertebra.  It  varies  at 
different  ages  :  most  commonly  it  increases  up  to  the  twenty-fifth  year,  but  occasionally 
its  growth  is  completed  before  this  period.  In  the  adult  it  remains  unaltered,  but  in  old 
age  it  becomes  shortened  by  the  incurvation  of  the  trunk  forward,  and  the  yielding  of 
the  bodies  of  the  vertebrsB  and  the  intervertebral  substances.  This  latter  cause  is  also 
productive  of  a  very  appreciable  shortening  of  the  trunk,  sometimes  to  the  extent  of  half 
an  inch,  after  long  walking  or  standing. 

When  measured  along  its  curvatures,  the  length  of  the  column  is  generally  two  feet 
four  inches  ;  in  vertical  height  it  is  two  feet  two  inches.  These  dimensions  are  not  ex- 
actly proportional  to  the  height  of  the  individual,  which  depends  principally  upon  the 
length  of  the  lower  extremities.  In  this  respect  I  have  never  found  any  marked  differ- 
ence between  tall  and  short  persons.  In  an  adult  of  medium  stature,  the  cervical  por- 
tion measures  five  inches  and  a  half,  the  dorsal  nine  inches  and  a  half,  the  lumbar  six 
inches  and  a  half,  and  the  sacro-coccygeal  six  inches  and  a  half 

It  may  be  easily  conceived  that,  in  cases  of  abnormal  curvature,  the  vertical  height 
must  present  considerable  differences,  while  the  actual  length  of  the  column  may  remain 
almost  constant.  In  the  skeleton  of  a  female  affected  with  rickets,  a  vertical  line, 
stretched  from  the  tubercle  of  the  atlas  to  the  base  of  the  sacrum,  measured  one  foot, 
six  inches,  and  six  lines  ;  while  a  line  which  followed  the  inflections  of  the  column,  meas- 
ured two  feet  eighteen  lines — giving  a  difference  of  seven  inches.  Hence  the  possibil- 
ity of  a  rapid  and  considerable  increase  in  length  in  those  patients  who  are  submitted  to 
continued  extension. 

2.  Antero-posterior  dimensions.  The  antero-posterior  diameter,  at  the  sacro-vertebral 
angle  and  in  the  lumbar  region,  is  three  inches ;  in  the  dorsal  region,  two  inches,  four 
lines  ;  in  the  middle  of  the  cervical  region,  one  inch,  six  lines. 

3.  Trmisverse  dimensions.  The  transverse  diameter  is  eighteen  lines  in  the  lumbar 
region,  thirteen  in  the  middle  of  the  dorsal,  and  twenty-two  in  the  cervical.  It  should, 
however,  be  remarked,  that  the  transverse  processes  are  included  in  this  measurement 
of  the  cervical  region,  but  not  in  the  others. 

Direction. 

The  general  direction  of  the  spinal  column  is  vertical,  but  it  presents  certain  alternate 
curvatures.  There  are  four  antero-posterior  curvatures,  viz.,  in  front,  a  convexity  in  the 
neck  (a,  b,fig.  1),  a  concavity  in  the  dorsal  region  (b,  c),  a  convexity  in  the  loins  (c,  d), 
and  a  concavity  in  the  sacro-coccygeal  region  {d,  e,  /).  Behind,  the  opposite  curvatures 
are  observed.  The  degree  of  each  curvature  is  always  proportioned  to  that  of  the  oth- 
ers ;  thus,  if  there  be  a  remarkable  projection  in  the  cervical  region,  there  is  a  corre- 
sponding degree  of  concavity  in  the  dorsal,  and  a  proportional  convexity  in  the  lumbar 
regions.  So  great,  indeed,  is  the  mutual  dependance  of  these  curvatures,  that  the  slight- 
est modification  of  one  produces  corresponding  alterations  in  all  the  others. 

There  are  many  individual  varieties  of  these  curvatures  ;  their  effect  appears  to  be 
that  of  augmenting  the  power  of  resistance  in  the  vertical  direction,  or,  at  least,  of  di- 
minishing the  effect  of  vertical  pressure.  It  may  be  physically  demonstrated,  that  of  two 
similar  rods  made  of  the  same  materifils,  that  which  presents  alternate  curves  will  sup- 
port a  greater  amount  of  pressure  in  the  vertical  direction  than  that  which  is  straight, 
on  account  of  the  decomposition  of  forces  which  occurs  at  each  curvature.* 

In  addition  to  these  antero-posterior  curvatures,  there  is  at  the  level  of  the  third, 

*  Some  physiologists  have  even  gone  so  far  as  to  express  by  figures  what  the  difference  of  resistance  of  a 
'ecto-lineal  vertebral  column  would  be,  as  compared  to  one  formed  with  curves  like  the  spine,  and  have  made 
It  as  1  ;  16.  It  has  also  been  asserted,  that  the  curvatures  of  the  spinal  column  were  the  result  of  muscular 
action.  This  is  certainly  not  the  fact.  These  curves  are  too  fixed  and  too  important  to  be  made  to  dopend 
on  an  agent  so  variable  as  that  of  muscular  contraction.  They  are  produced  by  the  general  law  which  regu- 
lates the  organization  of  the  body. 


THE    VEETEBRAL  COLUMN.  29- 

fourth,  and  fifth  dorsal  vertebrae  a  lateral  inclination,  the  concavity  of  which  is  on  the  lefl 
side.  This  being  the  exact  situation  in  which  the  aorta,  the  principal  artery  of  the  body, 
makes  a  curve  downward,  the  older  anatomists  have  ascribed  the  concavity  of  which 
we  speak  to  the  curvature  of  this  vessel.  Bichat  imagined  it  to  be  owing  to  the  ahnost 
universal  habit  of  employing  the  right  hand,  in  which  action  the  upper  part  of  the  trunk 
is  inclined  to  the  left,  so  as  to  afford  a  point  of  support,  and,  as  it  were,  a  counterbalance 
to  the  action  of  the  right  arm,  which  inclination,  by  frequent  repetition,  becomes  perma- 
nent. According  to  this  hypothesis,  left-handed  individuals  should  present  a  curvature 
in  the  opposite  direction,  and  Beclard  has  shown  that  such  is  in  reality  the  case.  I  may 
add,  that  I  have  always  found  the  deviation  greatest  in  those  who  used  their  right  arm 
in  the  most  laborious  employments.  Of  late  years  it  has  been  supposed  that  the  lateral 
curvature  depended  upon  the  position  of  the  foetus  in  utero ;  had  this  been  the  case,  it 
should  exist  at  birth,  which,  as  I  can  affirm,  'it  never  does.  Notwithstanding  the  likeU- 
hood  of  Bichat's  opinion,  yet,  if  we  consider  that  in  every  case  in  which  an  artery  is  im- 
mediately contiguous  to  a  bone,  that  bone  presents  a  corresponding  depression,  it  may 
be  questioned  whether  the  opinion  of  the  older  anatoinists  has  not  more  foundation  than 
is  generally  admitted.*  However  slight  this  lateral  incurvation  may  be,  it  always  pro- 
duces a  correspondent  one  in  the  lumbar  region,  though  in  the  majority  of  cases  this  is 
scarcely  perceptible.  ^ 

The  history  of  abnormal  curvatures  or  deviations  belongs  to  pathological  anatomy.  I 
shall  only  observe,  that  they  are  all  due  to  the  following  causes  :  1.  The  wasting  of  the 
vertebrae  by  caries  or  softening.  2.  Want  of  equilibrium  between  the  strength  of  the 
vertebral  column  and  the  weight  of  the  body,  either  alone  or  when  loaded  with  burdens. 
3.  Muscular  traction.  4.  The  frequent  repetition  of  any  attitude»in  which  the  column 
is  curved. 

Figure  and  Aspects. 

Viewed  in  front,  the  vertebral  column  represents  two  pyramids  united  by  their  bases. 
The  inferior  pyramid  is  constituted  by  the  sacrum  and  coccyx: ;  the  superior  pyramid  is 
the  true  spine ;  its  base  rests  on  the  former,  and  its  summit  is  surmounted  by  the  atlas. 

The  contraction  which  exists  at  the  fourth  and  fifth  dorsal  vertebra;  has  led  to  the 
subdivision  of  this  superior  pyramid  into  two  others,  united  by  their  summits.  Other 
subdivisions  have  been  instituted,  which  we  shall  not  point  out,  since  they  are  useless. 
What  it  is  important  to  know  is,  that  the  vertebral  column  increases  progressively  in  size 
from  above  downward,  which  satisfactorily  proves  that  man  was  formed  for  the  erect  posi- 
tion. There  are  partial  enlargements  in  different  parts,  as,  for  instance,  in  the  first  two 
cervical  vertebrae,  in  the  seventh  cervical,  and  last  dorsal,  &c. 

Upon  the  whole,  it  may  be  said  that  the  vertebral  column  presents  in  front  the  appear- 
ance of  a  knotted  cylinder ;  behind,  that  of  a  triangular  pyramid,  bristled  with  eminences 
and  perforated  with  holes.  How  irregular  does  the  spine  appear  when  cursorily  exam- 
ined !  Yet,  when  viewed  as  a  whole,  and  when  we  examine  its  figure  and  processes  in 
reference  to  its  uses,  we  are  lost  in  admiration  in  perceiving  that  there  is  not  the  small- 
est tubercle,  nor  the  most  minute  hole,  nor  the  most  trifling  circumstance  in  its  configu- 
ration, which  is  not  of  great  importance  in'  securing  the  perfection  of  the  entire  colunm. 

The  vertebral  column  presents  for  coilsideration  an  anterior,  a  posterior,  and  two  lat- 
eral surfaces,  a  base,  and  a  summit. 

Anterior  Surface. — Here  are  observed,  1.  The  curvatures  already  described ;  2.  The 
range  of  bodies  of  the  vertebrae,  having  the  form  of  small  columns  piled  on  each  other 
and  separated  in  the  fresh  state  by  certain  prominent  disks  of  a  white  colour  and  fibrous 
structure.  3.  A  range  of  transverse  grooves  on  the  bodies  of  the  vertebrae,  which  are 
deeper  in  the  aged  than  in  the  young  subject.  This  surface  presents  in  its  transverse 
diameters  those  variations  which  we  have  already  noticed.  The  parts  placed  in  front 
of  the  vertebral  column  are,  1.  Immediately  on  its  anterior  surface  a  ligamentous  layer, 
which  completely  invests  it,  with  the  anterior  recti  muscles  of  the  head,  the  longi  colli, 
the  crura  of  the  diaphragm,  and  the  psoae  muscles.  2.  At  a  greater  distance  the  aliment- 
ary canal,  which  rests  on  the  spine  at  its  commencement  and  termination,  and  is  attach- 
ed to  it  by  membranous  connexions,  even  where  it  advances  forward  to  form  its  numer- 
ous convolutions.  3.  The  organs  of  circulation,  viz.,  the  heart,  the  aorta,  in  almost  its 
whole  extent,  the  carotid,  vertebral,  and  common  iliac  arteries,  the  venae  cavae,  the  ju- 
gular and  common  iliac  veins,  the  vena  azygos,  and  the  thoracic  duct.  From  this  posi- 
tion of  parts  arises  the  possibility  of  effectually  compressing  the  arteries  against  the  ver- 
tebral column,  a  method  which  has  been  successfully  adopted  with  the  carotid  arteries 
and  abdominal  aorta.  It  also  explains  the  marked  pulsations  in  the  abdominal  region 
frequently  observed  in  emaciated  subjects,  and  often  giving  rise  to  an  erroneous  suspi- 

*  This  opinion  seems  to  be  still  farther  corroborated  by  a  case  lately  reported  to  the  Academy  of  Medicine 
by  Doctor  Gery,  of  complete  inversion  of  the  viscera,  where  the  aorta  was  placed  on  the  right  side  of  the  ver- 
tebral column,  and  where  the  concavity,  or,  rather,  lateral  depression,  was  situated  on  tlie  right  side.  The 
facts  of  the  case  are  satisfactorily  established  by  M.  Bonamy,  who  examined  the  subject.  Positive  proof  was 
obtained  that  this  individual  was  not  left-handed. 


b 


30  OSTEOLOGY. 

cion  of  aneurism.  4.  The  trachea  and  the  lungs.  5.  The  great  sympathetic  nerves  are 
connected  with  it  in  its  entire  extent,  and  the  ganglionic  enlargements  of  which  corre- 
spond in  number  to  the  number  of  its  different  pieces. 

Posterior  Surface. — This  presents,  1.  In  the  median  line,  the  row  of  spinous  processes, 
the  whole  of  which  constitute  a  vertical  crest  or  ridge  denominated  spine,  and  hence  the 
names  spinal  column  and  rachis  {(iaxk,  spine).  This  ridge  is  far  from  being  regular,  but 
its  irregularities  are  all  perfectly  adapted  for  the  fulfilment  of  the  movements  of  the  dif- 
ferent regions.  It  commences  with  the  tubercle  of  the  first  vertebra,  is  suddenly  en- 
larged at  the  second,  diminishes  again  at  the  third,  fourth,  and  fifth  cervical  vertebrae, 
and  projects  anew  at  the  sixth,  and  more  remarkably  at  the  seventh ;  thence  named 
vertebra  prominens.  Below  this  point  the  processes  become  oblique,  prismatic,  trian- 
gular, and  with  one  tubercle :  their  obliquity  increases,  but  they  become  more  slender 
from  the  first  to  the  tenth :  in  the  tenth,  eleventh,  and  twelfth  dorsal,  they  become  hor- 
izontal, shorter,  and  stronger ;  and  they  are  broad,  square,  rectangular,  and  horizontal 
in  the  lumbar  region.  Lastly,  the  ridge  gradually  sinks  down  in  the  sacro-coccygeal  re- 
gion, when  it  ends  by  dividing  into  two  smaller  ridges,  leaving  between  them  a  furrow, 
which  is  continued  along  the  coccyx.  We  cannot  fail  to  perceive  the  importance  of  the 
most  trifling  circumstance  in  the  conformation  of  the  spinal  ridge,  whether  examined  in 
reference  to  physiology  or  pathology.  1st.  In  reference  to  physiology.  This  ridge  must 
be  viewed  as  the  lever  of  those  powers  which  produce  extension.  We  know  that  the 
movements  of  extension  are  greatest  in  the  cervical  portion,  that  they  scarcely  exist  in 
the  dorsal,  and  are  again  considerable  in  the  lumbar.  The  interval  between  the  spinous 
processes  measures  the  extent  of  motion.  The  three  enlargements  above  referred  to, 
viz.,  that  of  the  second  cervical  vertebra,  that  of  the  seventh  cervical  and  first  dorsal, 
and  that  of  the  twelfth  dorsal  and  first  lumbar,  explain  these  movements.  The  first  is 
for  the  articulation  of  the  particular  movements  of  the  head,  the  second  for  the  move- 
ments of  the  neck,  and  the  third  for  the  insertion  of  the  extensor  muscles  of  the  loins. 
2d.  In  reference  to  pathology.  The  spinal  ridge  being  the  only  part  of  the  vertebral 
column  which  we  can  see  or  feel  in  the  living  subject,  it  is  clearly  of  the  greatest  im- 
portance to  study  the  shghtest  differences  which  it  presents,  because  it  is  thus  alone 
that  we  are  able  to  judge  of  the  extent  of  deviation  in  the  column ;  and  yet  the  indica- 
tions it  affords  are  not  absolutely  certain,  because  the  pedicles  of  the  vertebrae  being 
susceptible  of  torsion,  a  curvature  may  exist  in  the  bodies  of  the  vertebrae  without  any 
corresponding  alteration  of  the  spinous  processes. 

2.  On  each  side  of  this  median  ridge  are  two  grooves,  broad  and  shallow  in  the  cervi- 
cjil,  broad  and  deep  in  the  upper  part  of  the  dorsal  region,  contracted  at  the  lower  part  of 
the  back,  enlarged  again  in  the  loins  and  at  the  base  of  the  sacrum,  contracted,  and  final- 
ly obliterated,  at  the  lower  part  of  this  bone.  These  grooves  are  filled  by  a  muscular 
mass,  which,  in  robust  individuals,  projects  beyond  the  spine,  while  in  those  who  are 
emaciated  the  ridge  forms  the  most  prominent  part. 

Lateral  Surfaces. — ^These  present,  1.  In  front,  the  sides  of  the  bodies  of  the  vertebrae 
and  their  transverse  grooves,  which  are  deeper  at  the  sides  than  in  front,  also  deeper  in 
the  loins  than  in  the  neck  and  back ;  2.  In  the  dorsal  region,  facettes  for  the  costo-ver- 
tebral  articulations  ;  3.  Still  more  posteriorly,  the  intervertebral  foramina,  equal  in  number 
to  that  of  the  vertebrae.  The  largest  of  these  foramina  is  the  one  situated  between  the 
fourth  and  fifth  lumbar  vertebrae  :  from  this  point  they  gradually  diminish  in  size  to  the 
upper  part  of  the  back :  in  the  cervical  region,  again,  they  are  somewhat  larger ;  and  in 
the  sacro-coccygeal  they  are  double,  with  an  anterior  and  a  posterior  opening,*  in  con- 
sequence of  the  later2il  conjunction  of  the  false  vertebrae  of  the  sacrum.  In  general, 
their  dimensions  are  in  proportion  to  the  size  of  the  veins  which  communicate  between 
the  intra  and  the  extra  vertebral  venous  system.  Between  these  foramina  are  the 
transverse  processes,  which  contribute  to  form  the  sides  of  the  posterior  grooves,  and, 
between  the  transverse  processes,  the  articulating  processes  are  visible. 

The  base  and  the  summit  of  the  vertebral  column  have  been  already  considered,  in  the 
special  description  of  the  atlas  and  the  fifth  lumbar  vertebra. 

Vertebral  Canal. — ^This  canal,  into  which  the  intervertebral  foramina  open,  follows  all 
the  curves  of  the  spinal  column,  but  does  not  altogether  correspond  in  shape  with  its 
external  figure.  It  may  be  even  said  that  its  dimensions,  at  different  heights,  bear  an 
inverse  proportion  to  those  of  the  column ;  thus,  while  the  canal  is  most  capacious  in 
the  neck,  the  column,  on  the  other  hand,  is  largest  in  the  loins.  It  has  been  said  that 
the  widest  portions  of  the  canal  correspond  with  the  enlargements  of  the  spinal  cord : 
but  this  is  not  correct.  The  capacity  of  the  canal  is  proportioned  to  the  mobility  of  the 
respective  portion  of  the  column,  so  that,  in  the  most  extensive  movements,  the  spinal 
marrow  is  effectually  guarded  from  compression :  thus  it  is  largest  in  the  neck  and  loins, 
and  smallest  in  the  back  and  sacrum,  t 

*  [The  foramina  which  lead  from  the  sacred  canal  are  single  at  their  internal  orifices,  though,  for  the  rea- 
son given  in  the  text,  they  open  externally  by  two  orifices.  It  is  the  internal  orifice  which  answers  to  the 
intervertebral  foramen  of  the  other  vertebrae.] 

t  In  the  Philos.  Trans.,  1822,  Mr.  Earl  has  published  a  paper  to  establish  this  fact  from  observatioa  in 
comparative  anatomy. 


THE    VERTEBRAL   COLUMN.  31 

The  canal  is  almost  equally  well  protected  in  front  and  behind :  anterloily  by  the 
bodies  of  the  vertebrae,  posteriorly  by  the  spinous  processes,  which,  as  it  were,  ward  off 
mischief  from  the  spinal  canal.  Laterally  it  is  defended  by  the  articular  and  transverse 
processes.  Behind,  on  each  side  of  the  median  ridge,  it  is  protected  by  the  laminae,  the 
intervals  of  which  are  filled  up  by  what  are  named  the  yellow  ligaments.  Any  loss  of  se- 
curity occasioned  by  the  existence  of  these  yellow  ligaments  is  compensated  by  the  fol- 
•lowing  circmnstances  :  1.  The  ligaments  are  very  short,  so  that  the  edges  of  the  laminte 
are  almost  contiguous.  2.  In  the  neck,  where  the  intervals  are  greatest,  the  laminae 
are  so  inclined,  that  the  inferior  border  of  the  one  above  overlaps  the  superior  border  of 
the  one  below.  3.  In  the  loins,  where  the  intervals  are  nearly  as  great,  the  laminae  are 
small,  and  their  place  is  in  a  great  measure  occupied  by  the  lateral  masses  and  the  pedi- 
cles, which  are  proportionally  increased  in  development.  It  is  impossible  for  an  instru- 
ment to  penetrate  into  the  canal  in  the  lumbar  region,  excepting  between  the  spinous 
processes.  The  same  difficulty  exists  in  the  cervical  region  during  extension,  on  ac- 
count of  the  imbrication  of  the  laminae.  During  forcible  flexion,  however,  an  instrument 
may  enter  between  them,  when  directed  from  below  upward. 

Internal  Structure  of  the  Vertebrce. 

Excepting  the  thin  external  layer  of  compact  tissue,  the  bodies  of  the  vertebrae  arc 
almost  entirely  composed  of  open,  spongy  texture.  The  different  processes,  on  the 
other  hand,  have  a  considerable  quantity  of  compact  tissue ;  but,  in  all  places  where  they 
undergo  any  enlargement,  they  are  cellular.  The  laminae  are  formed  almost  exclusively 
of  compact  tissue.  This  abundance  of  the  spongy  tissue  explains  the  fact  of  the  weight 
of  the  spinal  column  being  so  inconsiderable  in  proportion  to  its  size. 

The  venous  canals  are  larger  in  the  vertebrae  than  in  any  other  bones.  They  are,  for  the 
most  part,  arranged  within  the  body  of  the  bone  in  the  following  manner :  A  single  canal, 
directed  horizontally,  and  from  behind  forward,  conunences  at  the  posterior  surface  of 
the  body  of  the  vertebra ;  at  the  distance  of  a  few  lines  from  its  commencement,  it  divides 
into  two,  three,  or  four  canals,  which  diverge  from  each  other,  and  terminate  partly  upon 
the  anterior  surface  of  the  bone,  partly  in  the  cells  in  its  interior ;  all  these  canals  are 
lined  by  a  thin  layer  of  compact  tissue,  and  perforated  by  foramina. 

Development. 

The  development  of  the  vertebral  column  comprises,  1.  That  of  the  vertebrae  in  gen 
eral ;  2.  That  of  certain  vertebrae  which  differ  from  the  rest ;  and,  3.  That  of  the  column 
considered  as  a  whole. 

Development  of  the  Vertehrcz  in  general. — Each  vertebra  is  developed  at  first  from  three 
points  of  ossification,*  viz.,  one  median  for  the  body,  and  two  lateral  for  the  rest  of  the 
vertebral  ring.  To  these  primitive  points  are  added,  at  different  periods,  five  secondary 
or  epiphysary  points,  viz.,  one  for  the  summit  of  each  transverse  process,  one  for  the 
siunmit  of  the  spinous  process,  and  two  for  the  body,  the  one  on  the  superior  surface, 
the  other  on  the  inferior  surface,  where  they  form  two  very  thin  plates,  so  that  at  one 
time  the  body  of  every  vertebra  of  the  spine  is,  in  fact,  a  triple  disk.  Lastly,  there  is  a 
complementary  point  for  each  apophysary  tubercle  of  the  lumbar  vertebrae,  which  gives 
to  this  class  of  vertebrae  seven  secondary  points  of  ossification. 

The  first  osseous  points  generally  appear  in  the  laminae  ;  they  precede,  by  some  days, 
the  deposition  of  bone  in  the  bodies.  This  law,  however,  as  Beclard  has  remarked,  is 
by  no  means  general. 

The  first  ossific  points  are  visible  from  the  fortieth  to  the  fiftieth  day ;  that  in  the  body 
occupies  the  centre  of  the  cartilage,  under  the  form  of  an  osseous  granule,  which  ex- 
tends horizontally,  so  as  to  present  a  lenticular  aspect.  The  points  of  ossification  of  the 
laminae  appear  in  the  situation  of  the  future  transverse  and  articular  processes. 

The  complementary  osseous  points  are  not  formed  until  the  fifteenth  or  eighteenth 
year.  Sometimes,  however,  as  Bichat  has  observed,  the  point  for  the  summit  of  the 
spinous  process  is  included  among  the  primitive  nuclei,  and  in  such  cases  it  is  situated 
at  the  place  where  that  process  becomes  continuous  with  the  laminae. 

The  lateral  osseous  points  are  always  united  together  before  joining  the  body  of  the 
bone  :  this  union  commences  about  a  year  after  birth ;  they  are  not  united  with  that  oi 
the  body  until  about  four  years  and  a  half  The  lateral  points  are  so  joined  to  the  cen- 
tral one  that  they  form  the  sides  of  the  body,  and  in  the  cervical  region,  from  their  more 
rapid  increase,  they  constitute  of  themselves  fully  two  fifths  of  the  body  of  the  vertebra. 
It  is,  then,  on  the  body  of  the  vertebra,  or  on  what  is  essentially  the  articular  part  of  the 
bone,  that  the  three  primitive  points  are  united  together.  The  epiphysary  points  of  the 
transverse  and  spinous  processes  are  joined  to  the  rest  from  the  twentieth  to  the  twen- 
ty-fifth year ;  the  union  of  the  epiphysary  laminae  of  the  bodies  is  not  completed  imtil 
from  the  twenty-fifth  to  the  thirtieth  year. 

*  Some  anatomists  admit  two  primitive  points  for  the  body  of  the  vertebra.  It  would  •xceed  our  limitf  to 
give  an  account  of  the  discussions  to  which  this  question  of  osteogeny  has  given  rise. 


I 


88t  OSTEOLOGY. 

Development  of  particular  Vertebra. — Those  vertebrae  which  present  great  differences 
of  form  present  striking  differences,  also,  in  their  mode  of  development ;  such  are  the 
atlas,  axis,  seventh  cervical  vertebra,  first  lumbjir,  and  those  which  constitute  the  sa- 
crum and  coccyx. 

Adas. — Modern  anatomists  admit  five  or  six  points  of  ossification  for  this  bone  ;  one 
or  two  for  the  anterior  arch,  two  for  the  lateral  masses,  and  two  for  the  posterior  arch. 
I  have  never  observed  more  than  two  lateral  points,  the  same  point  belonging  at  once 
to  the  lateral  masses,  and  half  of  the  arch  on  each  side.  They  appear  in  the  following 
order :  those  for  the  posterior  arch  make  their  appearance  from  the  fortieth  to  the  fiftieth 
day ;  those  for  the  anterior  arch  not  until  during  the  first  year  after  birth.  The  two 
osseous  points  of  the  posterior  arch  unite  together,  those  of  the  anterior  arch  do  the 
same,  and  then  the  anterior  is  united  to  the  posterior  arch. 

Axis. — There  are  often  two  osseous  points  for  the  body  of  this  bone,  and  always  two 
lateral  ones  for  the  odontoid  process  :  it  has,  therefore,  in  all,  five  or  six  points,  viz., 
two  for  the  laminae  or  posterior  arch,  one  or  two  for  the  body,  and  two  for  the  odontoid 
process.  Meckel  and  Nesbit  admit  one  other  nucleus  between  the  odontoid  process  and 
the  body,  which  appears  in  the  course  of  the  first  year  after  birth.  The  points  in  the 
laminae  appear  from  the  fortieth  to  the  fiftieth  day ;  those  in  the  body  during  the  sixth 
month  ;  and  those  in  the  odontoid  process,  a  short  time  after.  At  birth  the  body  of  the 
axis  is  proportionally  more  developed  than  that  of  the  other  vertebrae.  The  union  of  its 
several  parts  takes  place  in  the  following  order :  the  two  laminae  are  joined  together 
shortly  after  birth ;  the  two  points  of  the  odontoid  process  remain  distinct  during  the 
whole  of  the  first  year ;  the  body  and  the  odontoid  process  are  united  in  the  course  of 
the  third  year  ;  and  the  laminae  and  the  body  during  the  fourth  or  fifth  year. 

Seventh  Cervical  Vertebra. — Independently  of  the  osseous  points  common  to  all  the 
vertebra;,  this  bone  has  two  others  situated  on  each  side  of  the  body  in  the  cartilage 
which  forms  the  anterior  half  of  the  transverse  process.  The  existence  of  this  point, 
which  was  described  by  Hunauld,  but  which  does  not  appear  to  me  to  be  constant, 
establishes  an  analogy  between  the  transverse  processes  of  the  cervical  vertebrae  and 
the  ribs  ;  it  represents  in  a  rudimentary  state  the  permanent  cervical  ribs  of  some  ani- 
mals ;  and  explains  an  anomaly  which  is  not  very  uncommon  in  the  human  subject,  viz., 
the  existence  of  a  supernumerary  cervical  rib. 

First  Luvibar  Vertebra. — Its  transverse  process  is  sometimes  developed  by  a  point  which 
remains  separate  from  the  body  of  the  bone,  and  forms  a  supernmnerary  lumbar  rib. 

Development  of  the  Sacrum  and  Coccyx. — The  first  three  sacral  vertebrae  each  present 
five  primitive  points,  viz.,  one  for  the  body,  two  for  the  laminae,  and  two  for  the  anterior 
portion  of  the  lateral  masses.     The  last  two  sacral  vertebrae  have  only  three  points. 

Each  of  the  coccygeal  vertebrae  is  developed  from  one  point  only,  but  it  is  not  uncom- 
mon to  see  the  first  two  formed  by  two  lateral  points,  which  subsequently  unite  in  the 
median  line  :  there  are,  therefore,  twenty-one  primitive  points  in  the  sacrum,  and  four 
in  the  coccyx.  Subsequently  two  epiphysary  laminae  are  formed  for  the  body  of  each 
sacral  vertebra,  making  ten  new  complementary  osseous  points.  At  a  still  later  period 
two  laminae  are  developed,  one  on  each  side  of  the  sacrum,  corresponding  with  the  au- 
ricular surface,  so  that  the  whole  number  of  osseous  points  in  the  sacrum  is  thirty-three. 

Ossification  proceeds  more  slowly  in  the  sacral  and  coccygeal  vertebrae  than  in  the 
others  :  it  commences  in  the  body,  the  first  points  appearing  from  the  second  to  the  third 
month  in  the  first  three  sacral  vertebrae,  from  the  fifth  to  the  sixth  month  in  the  fourth 
and  fifth  vertebrae ;  the  laminae  begin  to  ossify  in  the  interval  between  the  sixth  and 
ninth  month  :  the  first  vertebra  of  the  coccyx  usually  begins  to  ossify  during  the  first 
year  after  birth  ;  the  second,  from  the  fifth  to  the  tenth ;  the  third,  from  the  tenth  to  the 
fifteenth  ;  and  the  fourth,  from  the  fifteenth  to  the  twentieth  year. 

The  union  of  the  osseous  points  takes  place  at  different  times  ;  the  osseous  pieces  of 
each  vertebra  are  first  joined  together,  and  subsequently  the  vertebrae  themselves. 

1.  Union  of  the  Osseous  Nuclei  of  each  Vertebra. — The  osseous  points  of  the  laminae  are 
first  united  ;  these  then  join  with  the  anterior  lateral  nuclei  of  the  first  three  vertebrae : 
at  a  much  later  period  the  lateral  masses  become  connected  with  the  body. 

The  union  of  the  lateral  masses  with  the  body  takes  place  much  earlier  in  the  fourth 
and  fifth  sacral  vertebrae  than  in  the  three  others,  though  these  latter  first  showed  osse- 
ous points.  After  the  union  of  the  lateral  masses,  the  sacrum  is  composed  of  five  pieces, 
which  remain  separate  until  the  fifteenth  year. 

2.  Union  of  the  Sacral  Vertebra,  with  one  another. — This  process  commences  between 
the  fifteenth  and  eighteenth  year,  at  which  time  the  epiphysary  laminae  of  the  bodies  of 
the  sacral  vertebra;  are  developed.  At  the  age  of  twenty-five  the  epiphysary  laminae  of 
the  iliac  surface  of  the  sacrum  are  developed.  The  union  commences  with  the  lower 
vertebrae,  and  proceeds  upward.  The  first  is  not  completely  joined  to  the  others  until 
from  the  twenty-fifth  to  the  thirtieth  year. 

The  union  of  the  body  of  each  vertebra  with  its  epiphysary  laminae  proceeds  from  the 
circumference  to  the  centre,  so  that,  in  a  vertical  section  of  a  sacrum,  which  is  com- 
pletely ossified  externally,  we  often  find  an  intermediate  lamina  of  cartilage.    I  have 


THE    SCULL.  33 

Observed  this  cartilage  between  the  first  and  second  sacral  vertebrae  in  subjects  of  a 
yery  advanced  age. 

The  union  of  the  pieces  of  the  coccyx  takes  place  sooner  than  those  of  the  sacrum. 
It  commences  with  the  first  two  pieces  ;  the  third  and  fourth  then  follow ;  and,  in  the 
last  place,  the  second  and  third  are  united.  Towards  the  fortieth  or  fiftieth,  or  some- 
times the  sixtieth  year,  the  coccyx  becomes  united  to  the  sacrum.  This  junction  is 
later  in  the  female  than  in  the  male  ;  sometimes  it  never  takes  place. 

Development  of  the  Spine  in  general. — Up  to  the  end  of  the  first  month  of  conception, 
the  length  of  the  spine  is  commensurate  with  that  of  the  body,  the  extremities  as  yet 
only  existing  under  the  form  of  small  tubercles.  This  disproportion  between  the  spine 
and  members  is  gradually  effaced  by  the  elongation  of  the  limbs,  so  that  at  birth  the 
vertebral  column  does  not  constitute  more  than  three  fifths  of  the  height  of  the  subject. 
In  the  adult  it  forms  only  two  fifths.  / 

All  the  parts  which  concur  in  forming  the  canal  for  the  defence  of  the  spinal  cord  are 
developed  prior  to  those  which  are  specially  devoted  to  locomotion,  as  is  shown  in  the 
development  of  the  laminae,  as  compared  with  that  of  the  body  and  processes.  The  os- 
sification of  the  laminae  proceeds  in  regular  succession  from  above  downward,  from  the 
neck  to  the  sacro-coccygeal  region.  The  ossification  of  the  bodies  takes  a  different 
course,  commencing  in  the  dorsal  region  as  a  centre,  and  proceeding  to  either  extremity 
of  the  column.  The  ossification  of  the  bodies  of  the  vertebrae  commences  in  the  centre 
of  the  bone,  and  accordingly,  if  the  spine  of  a  foetus  be  dried,  the  cartilages  shrink,  and 
the  series  of  osseous  nodules,  which  represent  the  bodies  of  the  vertebrae,  look  like 
grains  of  Indian  corn  strung  together. 

In  the  first  periods  of  its  development,  the  spinal  column  presents  the  following  re- 
markable differences  from  its  subsequent  condition.  It  is  completely  devoid  of  curva- 
ture, and  instead  of  resembling  in  shape  a  pyramid  with  the  base  below,  it  is  precisely 
the  reverse,  the  base  of  the  pyramid  being  uppermost.  As  the  child  grows  up,  the  spine 
gradually  acquires  those  characters  which  it  presents  in  the  adult.  In  the  old  subject  it 
is  always  more  or  less  bent  forward.  It  is  not  uncommon  to  meet  with  several  dorsal 
or  lumber  vertebrae  more  or  less  completely  united  by  a  layer  of  bone,  which  forms  a 
sort  of  sheath  or  clasp.    To  this  I  have  apphed  the  name  of  Emchylosis  by  invagination. 


THE  SCULL. 

Composed  of  the  Cranium  and  Face. — Cranial  Bones. — Occipital. — Frontal. — Sphenoid.— 
Ethmoid. — Pafielal. — Temporal. — The    Cranium  in  general. — Development. — Bones  of 
the  Face. — Superior  Maxillary. — Palate. — Malar. — Nasal. — Lachrymal. — Inferior  Tui 
binated. — Vomer. — Inferior  Maxillary. — The  Face  in  general. — Cavities. — Development 

The  scull  is  the  most  complicated  portion  of  the  skeleton.  It  has  been  more  minute- 
ly investigated  than  any  other  part,  probably  on  account  of  the  difficulty  of  the  study.  It 
is  composed  of  two  distinct  portions  :  one,  the  cranium,  designed  to  enclose  and  protect 
the  brain ;  the  other,  the  face,  which  affords  lodgment  to  almost  all  the  organs  of  the 
senses,  and,  at  the  same  time,  is  employed  in  the  function  of  mastication. 

The  Cranium. 

The  cranium  {Kpdvog,  a  helmet)  is  a  round  osseous  case,  composed  of  eight  bones, 
that  is,  of  eight  pieces,  distinct  and  separable  after  the  complete  development  of  the 
skeleton.  Four  of  these  are  single,  and  placed  on  the  median  line,  viz.  (counting  from 
behind  forward),  the  occipital,  the  sphenoid,  the  ethmoid,  and  the  frontal ;  the  remaining 
four  are  in  pairs,  and  are  situated  laterally,  viz.,  the  two  parietal  and  the  two  temporal. 
To  these  must  be  added  the  two  small  supernumerary  bones  denominated  ossa  wormiana, 
or  triquctra. 

The  Occipital  Bone  (Jigs,  9  and  10). 

The  occipital  bone  occupies  the  posterior,  inferior,  and  middle  portion  of  the  cranium, 
a  great  part  of  the  base  of  which  it  constitutes.*  Below  it  is  articulated  with  the  ver- 
tebral column  ;  in  front  with  the  sphenoid  ;  and  it  is,  as  it  were,  wedged  in  between  the 
parietal  and  temporal  bones  of  the  right  and  left  sides.  It  is  broad  and  symmetrical ; 
in  shape,  an  irregular  segment  of  a  spheroid,  notched  round  the  circumference.  It  has 
an  anterior  and  a  posterior  surface,  and  a  circumference  having  four  borders  and  four  angles. 

The  posterior  or  cutaneous  surface  {fig.  9)  is  convex,  and  presents  the  inferior  orifice  of 
the  occipital  foramen  (1,  fig.  9 ;  d,  fig.  21),  (foramen  magnum),  the  largest  of  all  the  fora- 
mina in  the  skeleton,  excepting  the  sub-pubic,  or  obturator  foramen  of  the  os  innomina- 

*  It  is  the  OS  prora:  of  Fabricius  of  Aquapendente,  who,  following  out  the  same  metaphor,  has  given  tb« 
name  of  os  puppis  to  the  frontal,  and  os  carinoe  to  the  sphenoid. 

E 


H. 


OSTEOLOGY. 


turn.     It  gives  passage  to  the  spinal  marrow  with  its  envelopes,  the  spinal  accessory 


Fig.  9. 


nerves,  and  vertebral  arteries.  In  front  of  the  foramen  is  the 
inferior  surface  of  the  basUar  process  (2,  fig.  9 ;  n,  fig.  21), 
which  forms  the  bony  roof  of  the  pharynx ;  it  is  placed  hor- 
izontally, is  rough,  and  has  a  ridge  in  the  median  line,  more 
or  less  prominent  in  different  subjects.  Behind  the  foramen, 
and  in  the  median  line,  is  the  external  occipital  ridge  {perpe-ndic' 
ular  spine)  (3  4,^^.  9;  c  a,  fig.  21),  extending  from  the  poste- 
rior edge  of  the  foramen  to  the  external  occipital  protuberance. 
This  projection  is  wanting  in  some  individuals,  and  in  others 
its  place  is  occupied  by  a  depression.  On  each  side  of  the 
ridge  are  unequal  surfaces,  bounded  above  by  a  line,  with  the 
concavity  looking  downward.  Thus,  the  siiperior  semicirctdar 
line  (5  5,  fig.  9  ;  a  b,fig.  21)  commences  at  the  occipital  protu- 
berance (4,  fig.  9 ;  a,  fig.  20),  and  proceeds  horizontally  out 
ward.  The  irregular  surface  included  between  this  line  and 
the  foramen  is  again  divided  by  a  line  whose  concavity  is  directed  upward  (6  6,  fig.  9), 
and  which  is  called  the  inferior  semicircular  line.  These  lines  and  these  inequalities 
are  destined  to  receive  the  insertion  of  a  great  number  of  muscles. 

On  each  side  of  the  occipital  foramen,  and  towards  the  fore  part,  are  the  condyles  (7  7, 
fig.  9 ;  e,fig.  21),  two  articular  eminences,  convex,  elliptical,  directed  from  behind  for- 
ward, and  from  without  inward,  their  surfaces  looking  downward,  and  somewhat  out- 
ward. They  articulate  with  the  atlas.  Behind  these  are  two  fossae  :  the  posterior  con- 
dyloid,  which  are  often  perforated  by  an  aperture  ;  the  posterior  cmidyloii  foramen  (8,  figs. 
9  and  21),  giving  passage  to  a  vein.  In  front,  and  external  to  the  condyles,  are  the  an- 
terior condyloid  fosscz  and  foramina  (9  9,  fig.  9) ;  the  latter  are  really  flexuous  canals, 
through  which  the  hypoglossal  nerves  pass  out  of  the  scull.  External  to  the  condyles 
is  a  rough  surface,  the  jugular  surface  {i,fig.  21),  which  gives  attachment  to  the  recti 
laterales  muscles  of  the  head. 

The  anterior  internal  or  encephalic  surface  {fig.  10),  in  common  with  all  the  other  bones 


Fig.  10. 


of  the  cranium,  is  lined  by  the  dura  mater.  It  presents,  1. 
The  internal  orifice  of  the  occipital  foramen  {I,  fig-  10),  which 
is  larger  than  the  external.  2.  Before  the  foramen  the  ba- 
silar groove  (2),  sloping  gently  from  above  downward  and 
backward :  the  sides-  of  the  groove  are  marked  by  other 
very  small  grooves,  which  concur  in  forming  the  inferior 
petrosal  groove.  3.  On  each  side  of  the  occipital  foramen, 
and  towards  the  fore  part,  is  a  projection  (3  3)  which  corre- 
sponds with  the  condyle,  and  particularly  with  the  anterior 
condyloid  canal.  4.  A  little  more  external  and  posterior  is 
a  small  portion  of  a  groove  (4),  which  contributes  to  form 
the  termination  of  the  lateral  sinus.  5.  Behind  the  foramen 
are  the  four  occipital  fossce,  two  superior  or  cerebral  (5  5),  and 
two  inferior  or  cerebellar  (6  6),  separated  frohi  each  other  by 
a  crucial  ridge.  The  vertical  branch  of  this  ridge  {g  a)  joins 
the  termination  of  the  sagittal  groove  above ;  below  it  is 
formed  by  the  internal  occipital  crest  (7).  The  horizontal 
branches  (_g  b)  correspond  with  the  grooves  for  the  lateral 
sinuses  of  the  dura  mater.  The  internal  occipital  protuberance  (g)  is  situated  at  the  conflu- 
ence of  the  four  branches.  The  right  and  left  lateral  grooves  are  rarely  of  the  sEime 
size  and  depth ;  the  right  is  generally  the  larger,  and  forms  by  itself  the  continuation  of 
the  sagittal  or  longitudinal  groove. 

The  circumference  presents  four  borders  and  four  angles.  The  superior  or  parietal  bor- 
ders (a  b,  a  b),  which  are  remarkable  for  the  length  of  their  indentations,  articulate  with 
the  posterior  borders  of  the  parietal  bones  forming  the  lamdoidal  suture. 

The  inferior  or  temporal  borders  (b  c,  b  c)  are  divided  into  two  equal  portions  by  the  jugu^ 
lar  eminence  {d),  which  articulates  with  the  temporal  bone.  This  eminence,  in  most  sub- 
jects small,  in  some  instances  is  largely  developed,  so  as  to  form  a  true  jugular  process. 
I  have  seen  this  process  articulated  to  the  transverse  process  of  the  atlas.  The  part 
(J  d)  above  this  eminence  is  slightly  denticulated,  and  united  to  the  mastoid  portion  ot 
the  temporal  bone  ;  the  part  {d  c)  below  is  thick,  sinuous,  but  without  indentations,  and 
articulates,  by  juxtaposition,  with  the  petrous  portion  of  the  temporal.  In  front  of  the 
jugular  eminence  is  a  deep  notch,  sometimes  divided  into  two  parts  by  a  process  of 
bone,  which  contributes  to  form  the  foramen  lacerum  posterius. 

The  superior  angle  (a)  is  acute,  and  is  received  into  the  retreating  angle  formed  by 
the  posterior  borders  of  the  parietal  bones.  Its  place  is  sometimes  supplied  by  a  Wor- 
mian bone.  In  the  young  subject,  the  posterior  fontanelle  is  placed  here.  The  inferior 
angle  (c)  is  truncated,  and  very  thick ;  it  forms  the  basilar  process,  which  presents  a  rough 
articular  surface  for  union  with  the  body  of  the  sphenoid.    The  connexion  is  estabUshed 


FRONTAL    BONE.  35 

by  means  of  a  cartilage,  which  becomes  ossified  at  a  very  early  period,  so  that  many 
anatomists  describe  the  sphenoid  and  occipital  as  one  bone.* 

The  lateral  angles  {b  b)  are  very  obtuse,  and  are  received  into  the  retiring  angle  formed 
by  the  union  of  the  parietal  with  the  temporal  bone.  At  these  angles  the  latcreU  and  pos- 
terior fmitanelles  are  situated. 

Connexions. — The  occipital  articulates  with  six  bones ;  the  two  parietal,  the  two  tem- 
poral, the  sphenoid,  and  the  atlas. 

Structure. — The  part  of  this  bone  which  forms  the  occipital  fossae  consists  almost  ex- 
clusively of  compact  tissue.  It  is  here  extremely  thin,  especially  at  the  inferior  fossse. 
In  the  rest  of  its  extent  there  is  spongy  tissue  between  the  two  tables.  The  external 
table  is  much  thicker  and  less  brittle  than  the  internal,  which  is  named  vitreous,  on  ac- 
count of  its  fragility.  The  spongy  tissue  is  very  abundant  in  the  condyles  and  in  the  ba- 
silar process. 

Development. — The  occipital  bone  is  developed  from  four  points  :  one  for  the  squamous 
portion,  that  is,  the  part  of  the  bone  behind  the  foramen  magnum ;  one  for  each  lateral 
condyloid  portion  of  the  occipital,  and  one  for  the  anterior  or  basilar  portion.  These 
four  parts  are  considered  by  some  anatomists  as  so  many  distinct  bones,  which  they  de- 
scribe under  the  names  of  posterior  or  superior  occipital,  lateral  occipitals,  and  anterior 
occipital  or  basilar  bone.  The  first  point  of  ossification  appears  in  the  squamous  or  back 
part  of  the  bone,  under  the  form  of  a  small  oblong  plate,  placed  transversely  in  the  situ 
ation  of  the  protuberances.  I  have  never  seen  this  piece  formed  by  two  lateral  points. 
The  part  of  the  bone  of  which  we  are  speaking  is  always  visible  towards  the  middle  of 
the  second  month.  The  condyloid  portions  make  their  appearance  next,  and,  lastly,  the 
basilar  portion,  which  I  have  never  seen  developed  from  two  lateral  points.  In  a  foetus 
of  two  months  and  a  half,  the  ossified  part  of  this  process  presented  the  appearance  of  a 
linear  streak,  situated  exactly  in  the  median  line,  and  directed  from  before  backward. 
The  four  points  of  ossification  are  finally  united  at  the  foramen  magnum. 

Anatomists,  however,  are  not  at  all  agreed  respecting  the  number  of  points  of  ossifi- 
cation. Meckel  admits  eight  for  the  posterior  part  of  the  bone,  two  for  the  condyles,  and 
one  for  the  basilar  process.  Beclard,  on  the  other  hand,  admits  only  four  in  the  poste- 
rior part  of  the  bone.  His  opinion  is  founded  upon  the  existence  of  four  fissures  or  di- 
visions at  the  circumference  of  this  portion ;  viz.,  one  at  the  superior  angle,  which 
sometimes  gives  to  the  posterior  fontanelle  the  lozenge  shape  of  the  anterior ;  one  be- 
low, which  is  nothing  more  than  a  slight  notch  in  the  back  of  the  foramen  magnum ; 
and  two  on  each  side,  corresponding  to  the  posterior  lateral  fontanelles.  The  opinion 
of  Meckel  is  perhaps  grounded  upon  certain  abnormal  cases,  in  which  this  part  of  the 
bone  is  divided  into  a  considerable  number  of  pieces,  resembhng  so  many  Wormian 
bones  united  by  suture. 

The  Frontal  or  Coronal  Bone  {jigs.  11  and  12). 

The  frontal  bone  is  situated  at  the  anterior  part  of  the  scull,  and  above  the  face.  It 
is  symmetrical,  and  represents  a  considerable  segment  of  a  hollow  sphere.  From  its 
shape  it  has  been  compared  to  a  shell.  The  superior  three  fourths  are  curved,  placed 
vertically,  but  more  or  less  inclined  from  above  downward  and  forward ;  the  inferior 
fourth  is  flat  and  horizontal.  It  has  an  anterior,  a  posterior,  and  an  inferior  surface,  and 
three  borders. 

The  anterior  cutaneous  or  frontal  surface  is  smooth  and  convex ;  there  is  a  suture  in 
the  median  line  in  young  subjects,  which  in  the  adult  is  ^ig.  11. 

obhterated,  leaving  scarcely  any  trace  of  its  existence,  ex- 
cepting at  its  termination  below.  At  this  spot  there  is  a 
prominence  named  nasal  eminence  or  glabella  (or  middle 
frontal  eminence)  {I,  fig.  11). 

On  the  sides  of  the  median  line,  proceeding  from  above 
downward,  we  observe  two  smooth  surfaces ;  then  the 
frontal  eminences  (2  2),  two  projections  which  are  most 
strongly  developed  in  young  subjects ;  and  below  these,  on 
each  side  of  the  glabella,  the  superciliary  ridge,  an  arched 
elevation  which  forms  the  margin  of  the  orbit,  and  is  more 
prominent  towards  the  nose  than  externally.  Quite  at  the  outside  of'the  anterior  sur- 
face of  the  frontal,  there  is  a  small,  depressed,  triangular  surface  (4),  which  looks  directly 
outward,  and  is  separated  from  the  frontal  eminence  by  a  sort  of  crest,  running  upward 
and  backward  (5) :  it  forms  the  anterior  part  of  the  temporal  fossa. 

The  anterior  surface  of  the  frontal  bone  is  separated  from  the  skin  by  the  frontal,  or- 
bicular, and  corrugator  supercilii  muscles,  and  the  anterior  portion  of  the  cranial  apo- 
neurosis. 

The  inferior  or  orbito-ethmoidal  surface  {fig.  12)  presents  in  the  middle  a  large  rectan- 

*  A  reference  to  comparative  anatomy  would  seem  to  justify  this  view,  for  in  some  inferior  animals  the 
basilar  process  and  the  sphenoid  are  but  one  piece. 


OSTEOLOGY. 

'.W*!V't'^  ■  gular  notch  (6),  which  extends  the  whole  length  of  this 
surface  from  before  backward.  This  notch,  which  is 
named  ethmoidal,  because  it  receives  the  ethmoid  bone, 
has,  1.  In  front,  and  in  the  median  line,  a  prolongation, 
denominated  the  nasal  spine  (7) :  this  spine  is  rough  in 
front,  for  articulation  with  the  proper  nasal  bones :  be- 
hind it  is  marked  by  two  grooves,  separated  by  a  verti- 
cal ridge  ;  the  ridge  joins  the  perpendicular  lamella  of  the 
ethmoid,  and  the  two  grooves  form  part  of  the  vault  of 
the  nasal  fossae.  2.  Farther  back,  and  on  each  side,  is 
the  large  opening  of  the  frontal  sinuses.  3.  The  two 
borders  of  the  notch  are  marked  with  {b  d,  b  d)  incom- 
plete cells,  which  join  with  those  of  the  ethmoid.  4.  On 
the  same  borders  there  are  two,  or  sometimes  three 
^''a  small  grooves,  which  contribute  to  form  the  anterior  and 

posterior  internal  orhitary  canals. 

On  each  side  of  the  notch  is  the  orbital  plate  (9  9),  triangular  and  concave,  especially 
towards  the  external  margin,  where  there  is  an  excavation  for  the  lachrymal  gland  {fos- 
sa glandula  lachrymalis).  At  the  internal  margin  there  is  a  small  depression  for  the  at- 
tachment of  the  cartilaginous  pulley,  in  which  the  tendon  of  the  superior  oblique  muscle 
of  the  eye  is  reflected. 

The  posterior  or  cerebral  surface  is  concave,  and  marked  by  eminences  and  depressions 
corresponding  to  the  sulci  and  convolutions  of  the  brain,  and  by  furrows  for  arterial 
branches.  In  the  median  line  is  a  longitudinal  groove,  the  sides  of  which  unite  below, 
and  form  the  frontal  ridge,  which  terminates  in  a  foramen  called  foramen  cacum.  The 
ridge  is  sometimes  absent,  and  occasionally  the  place  of  the  foramen  is  occupied  by  a 
notch,  completed  by  the  ethmoid,  as  already  described.  On  each  side  of  the  median  line 
are  the  frontal  fossce,  which  are  deeper  than  the  corresponding  eminences  on  the  outside 
seem  to  indicate  :  below  are  the  orbital  prominences,  which  look  directly  upward,  and  form 
a  retiring  angle*  with  the  frontal  fossae  ;  they  are  covered  with  acuminated  eminences, 
which  are  received  into  the  anfractuosities  of  the  brain. 

The  superior  or  parietal  border  {b  a  b)  is  semicircular,  denticulated,  and  cut  obliquely  at 
the  expense  of  its  internal  plate  above,  and  of  its  external  below,  and  at  the  sides.  In 
the  middle,  it  forms  a  very  obtuse  angle  (a),  which  is  received  into  the  retiring  angle 
formed  by  the  parietal  bones.  In  young  subjects  this  angle  is  wanting ;  in  its  situation 
the  anterior  angle  of  the  anterior  fontanelle  is  placed. 

The  inferior  or  sphenoidal  border  {b  b  b)  is  very  short,  thin,  and  straight,  interrupted  by 
the  ethmoidal  notch,  and  adapted  to  the  smaller  wings  of  the  sphenoid.  It  terminates 
externally  at  its  junction  with  the  superior  border,  by  two  triangular  surfaces  slightly  in- 
dented, which  articulate  with  the  greater  wings  of  the  sphenoid. 

The  anterior  or  orUto-nasal  border  (c  c,  fig.  11)  presents  in  the  centre  the  nasal  notch  {d  d), 
articulated  in  the  middle  with  the  nasal  bones,  and  at  the  sides  with  the  ascending  pro- 
cesses of  the  superior  maxillae.  At  the  bottom  of  this  notch  is  the  anterior  surface  of 
the  nasal  spine.  On  each  side  we  observe  the  orbital  arch  (c  d),  more  sharp  and  thin  to- 
wards its  outer  end.  At  the  junction  of  the  internal  with  the  two  external  thirds  of  this 
arch  is  situated  a  foramen  (c),  or,  more  frequently,  a  notch  converted  into  a  foramen  by 
a  ligament ;  it  is  called  the  superciliary  or  supra-orbital  foramen,  and  gives  passage  to  the 
frontal  vessels  and  nerves.  At  the  bottom  of  this  notch  there  are  generally  one  or  more 
vascular  openings,  which  lead  into  the  diploe,  and  are  the  terminations  of  venous  canals, 
which  run  for  a  considerable  way  within  the  bone.  The  orbital  arch  terminates  on  each 
side  by  a  process  ;  the  inner  one,  internal  angular  process  (d),  is  broad  and  thin,  and  artic- 
ulates with  the  OS  unguis  ;  the  external  (c)  is  thick,  and  unites  with  the  malar  bone. 

Connexions. — The  frontal  is  articulated  with  twelve  bones  :  the  two  parietal,  the 
sphenoid,  the  ethmoid,  the  two  nasal  and  two  malar  bones,  the  ossa  unguis,  and  the 
two  superior  maxillary. 

Internal  Structure. — The  vertical  portion  and  external  orbital  processes  are  very  thick ; 
the  horizontal  part  is  very  thin,  and  hence  the  facility  with  which  instruments  can  pen- 
etrate the  cranium  through  the  roof  of  the  orbit.  It  contains  large  c&xiiies,  frontal  sinu- 
ses (a,  figs.  23  and  24),  which  open  in  the  ethmoidal  notch,  and  add  greatly  to  the  thick- 
ness of  the  bone  at  its  lower  part.  They  are  separated  by  a  septum,  which  is  often  bent 
to  one  side,  and  is  generally  imperfect.  The  capacity  of  these  sinuses  is  very  variable  ; 
they  often  extend  throughout  the  whole  of  the  orbital  plates,  almost  to  the  edge  of  the 
sphenoid.  The  study  of  these  sinuses,  which  are  connected  with  the  organ  of  smelling, 
is  of  great  importance  in  determining  the  facial  angle. 

Development. — The  frontal  bone  is  developed  from  two  lateral  points  of  ossification, 
which  appear  about  the  middle  of  the  second  month,  and  conunence  in  the  orbital  arches. 
At  this  time  the  edges  are  in  approximation  below,  but  above  are  separated  by  an  angular 

*  This  retiring  angle  measures  pretty  exactly  the  facial  angle. 


SPHENOID   BONE. 


3f 


interval,  which  forms  the  anterior  angle  of  the  anterior  fontanelle.  The  two  pieces  are 
united  by  suture  during  the  first  year ;  it  is  gradually  effaced  afterward,  being  longest 
visible  at  its  inferior  termination,  though  it  is  uncommon  to  find  it  permanent  through 
life.  Independently  of  these  general  changes  which  the  bone  undergoes  in  the  course 
of  its  development,  there  are  also  certain  peculiar  alterations  in  which  the  sinuses  are 
concerned.  These  cavities  make  their  appearance  during  the  first  year,  and  gradually 
increase  in  size,  not  only  up  to  the  period  of  manhood,  but  even  to  old  age. 

The  Sphenoid  Bone  {figs.  13  and  14). 

This  bone  has  received  its  name  from  the  Greek  word  a^rjv  [S.  wedge,)  because  it  is 
inserted  like  a  wedge  between  the  other  bones.     It  is  situated  at  the  anterior  and  mid- 
dle part  of  the  base  of  the  cranium  {fig.  23).     Almost  ^    j3 
all  anatomists  agree  in  considering  it  as  a  separate 
bone  ;  but  Soemmering  and  Meckel  describe  it  as  united 
with  the  occipital,  under  the  name  of  basilar  or  spheno- 
occipital bone.    It  is  a  single  and  symmetrical  bone,  con- 
sisting of  a  bodi/  or  central  part,  from  which  spring,  on 
each  side,  two  horizontal  portions,  the  greater  and  less- 
er wings  of  the  sphenoid ;  and  below  two  vertical  col- 
umns, the  pterygoid  processes.    It  has  been  compared  to 
a  bat  with  extended  wings.     We  shaU  consider  it  as 
divided  into  a  body  and  lateral  parts. 

The  body,  or  central  part,  is  of  a  cubical  form,  and  therefore  presents  six  surfaces. 

Superior  or  cerebral  surface  {of  a  d,fig.  13).  Proceeding  from  before  backward,  we 
observe,  1.  A  smooth  plane  surface  (a),  slightly  depressed  on  each  side,  over  which  the 
olfactory  nerves  pass.  2.  A  transverse  groove,  optic  groove  {b),  on  which  the  commis- 
sure of  the  optic  nerves  rests,  and  which  is  continuous  on  each  side  with  the  optic  fora- 
men (1  1).*  3.  A  deep  quadrilateral  fossa  (c),  in  which  the  pituitary  gland  is  lodged, 
called  the  sella  turcica,  supra-sphe7ioidal,  or  pituitary  fossa.  4.  On  the  sides  of  this  fossa, 
two  grooves,  named  cavernous  or  carotid  grooves,  because  they  correspond  to  the  carotid 
arteries  and  cavernous  sinuses.  Anteriorly  the  cavernous  groove  gives  attachment  to 
the  ligament  of  Zinn,  a  tendon  which  gives  origin  to  three  muscles  of  the  eye.  Near  its 
anterior  termination,  and  between  it  and  the  pituitary  fossa,  is  the  middle  clinoid  process,^ 
generally  nothing  more  than  a  simple  tubercle,  but  sometimes  sufficiently  developed  to 
unite  either  with  the  anterior  or  with  the  posterior  clinoid  processes,  the  former  case 
being  the  more  common.  5.  Behind  the  pituitary  fossa  we  observe  a  quadrilateral  plate 
{d),  directed  obliquely  from  above  downward  and  backward ;  its  anterior  surface 
forms  part  of  the  fossa,  its  posterior  surface  is  continuous  with  the  basilar  groove,  its 
lateral  edges  are  notched  for  the  fourth  and  sixth  pair  of  nerves,  and  the  superior  border, 
which  separates  the  basilar  groove  and  the  pituitary  fossa,  presents,  at  each  extremity, 
an  angular  process  (e),  the  posterior  clinoid  (from  kIivt],  a  bed,  from  a  supposed  resem- 
blance of  the  anterior  and  posterior  clinoid  processes  to  the  four  corners  of  a  bed). 
6.  From  the  lateral  and  anterior  parts  of  the  body  of  the  sphenoid  arise  two  triangular  pro- 
cesses (n  0,  n  o),  flattened  above  and  below,  extremely  thin  and  fragile,  and  directed 
transversely :  these  are  denominated  the  orbital  or  lesser  wings  of  the  sphenoid  {alee  mi- 
nores),  or  the  wings  of  Ingrassius,  from  the  anatomist  who  first  gave  a  good  description 
of  them.  The  superior  surface  of  these  processes  is  flat,  and  corresponds  to  the  ante- 
rior lobes  of  the  brain  ;  the  inferior  surface  forms  part  of  the  roof  of  the  orbits  ;  the  ante- 
rior edge  is  bevelled  below,  and  rests  upon  the  posterior  border  of  the  frontal  and  the  eth- 
moid ;  the  posterior  edge  is  thin  and  sharp  externally,  thicker  internally,  and  divides  the 
anterior  and  middle  fossae  of  the  base  of  the  cranium ;  the  summit  (o)  is  pointed,  and 
hence  the  processes  are  sometimes  called  ensiform  or  xiphoid ;  the  base  presents  the  in- 
ternal orifice  of  the  optic  canal  or  foramen  (1),  which  is  directed  outward  and  forward, 
and  gives  passage  to  the  optic  nerve  and  the  ophthalmic  artery.  The  base  of  the  lesser 
wing  terminates  behind  in  a  projecting  angle  (w),  which  forms  the  anterior  clinoid  process ; 
and  beneath  this  is  a  deep  notch,  sometimes  a  foramen,  for  the  carotid  artery.  Occasion- 
sdly  the  anterior  are  united  to  the  posterior  clinoid  processes  by  a  long  bridge  of  bone. 

AH  the  part  of  the  sphenoid  in  front  of  the  sella  turcica,  including  the  smaller  wings, 
forms  the  anterior  sphenoid  of  some  modern  anatomists.  In  this  portion  of  the  bone  the  an- 
terior fossae  of  the  base  of  the  cranium  are  situated.  The  remaining  portion  of  the  bone, 
placed  inferior  to  the  former,  constitutes  the  posterior  sphenoid,  and  in  this  the  middle 
fossae  are  situated.  The  separation  of  these  two  parts,  which  is  but  temporary  in  man, 
existing  only  during  the  early  months  of  foetal  Hfe,  is  permanent  in  quadrupeds. 

The  inferior  or  guttural  surface  of  the  body  {fig.  14)  presents,  in  the  median  hne,  a 
ridge  or  crest,  called  the  beak  of  the  sphenoid  or  rostrum  {g) ;  it  is  more  prominent  anteri- 
orly than  posteriorly,  is  received  into  a  groove  of  the  vomer,  and  is  continuous  with  the 

*  [The  groove  is  formed  on  an  eminence  named  the  olivary  process.^  •     j        i, 

f  When  the  middle  clinoid  processes  are  united  with  the  posterior,  they  are  then  also  joined  to  the  anterior. 


OSTEOLOGY 

'  %nterior  ridge  of  the  body  of  the  bone.  On  each 
side  is  a  deep  furrow  concealed  by  a  lamella  (on  each 
side  of  g),  under  which  the  edges  of  the  vomer  are 
insinuated.  At  the  bottom  of  this  furrow  is  seen 
the  orifice  of  a  temporary  canal,  which  exists  only  in 
young  subjects,  and  which,  passing  obliquely  through 
the  sides  of  the  bone,  opens  in  the  sphenoidal  fissure. 
This  canal  is  the  trace  of  the  still  incomplete  union 
of  the  anterior  and  posterior  sphenoid ;  it  disappears 
as  soon  as  the  sinuses  within  the  bone  are  developed. 
More  externally,  and  on  the  same  surface,  is  situated 
a  small  groove  running  from  before  backward,  which 
lorms  part  of  the  ptery go-palatine  canal,  along  which  an  artery  of  the  same  name  passes. 
Still  more  externally  are  the  pterygoid  processes  (6  m  h)  {Trrepv^,  ala),  two  large  projections 
directed  perpendicularly  downward.  In  front  their  surface  is  broad  above,  where  it  forms 
part  of  the  pterygo-m2ixilIary  fossa,  and  rough  below,  for  articulation  with  the  palate  bone. 
Behind  is  a  deep  fossa,  into  which  the  internal  pterygoid  muscle  is  inserted  :  it  is  named 
the  pterygoid  fossa,  and  is  formed  by  two  laminae,  named  the  external  and  internal  ptery- 
goid plates,  of  which  the  external  (b)  is  the  broader,  and  the  internal  (m)  the  longer.  At 
the  upper  part  of  the  internal  plate  is  an  elliptical  depression  called  the  scaphoid  fossa, 
which  gives  attachment  to  the  circumflexus  palati  muscle.  The  internal  surface  of  the 
pterygoid  process  contributes  to  form  the  external  wall,  and  posterior  opening  of  the  na- 
sal fossa  {h  i,  fig.  25).  The  outer  surface  of  the  external  plate  is  broad,  forms  part  of 
the  zygomatic  fossa,  and  gives  attachment  to  the  external  pterygoid  muscle.  Tlie  base 
of  the  pterygoid  process  is  pierced  from  before  backward  by  the  vidian  or  pterygoid  canal 
(6  6,  Jig.  14) ;  its  summit  is  deeply  bifurcated,  to  receive  the  tuberosity  of  the  palate  bone. 
The  internal  branch  of  this  bifurcation  (internal  pterygoid  plate)  is  very  delicate,  and  is 
curved  into  a  hook-like  process  (s)  {hamular  process),  round  which  is  reflected  the  tendon 
of  the  circumflexus  or  tensor  palati  muscle. 

The  anterior  or  ethmoidal  surface  of  the  body  of  the  sphenoid  presents,  1.  Above  and 
in  the  median  line,  a  small  horizontal  projecting  angle  {f,figs.  13  and  14),  which  artic- 
ulates with  the  posterior  border  of  the  cribriform  plate  of  the  ethmoid.  2.  Below  this,  a 
vertical  ridge  {f  g,fig.  14),  continuous  with  the  septum  of  the  sphenoidal  sinuses,  and 
articulating  with  the  perpendicular  lamella  of  the  ethmoid.  3.  On  each  side  the  open- 
ings of  the  sphenoidal  sinuses  (7  7).  These  are  two  in  number ;  they  are  separated 
from  each  other  by  a  septum,  which  inclines  sometimes  to  the  right  side,  sometimes  to 
the  left,  and  are  subdivided  into  a  number  of  irregular  cells.  They  are  wanting  in  the 
young  subject,  but  acquire  a  great  size  in  the  adult,  occupying  the  whole  body  of  the 
sphenoid,  and  extending  into  the  base  of  the  lesser  wings,  and  even  occasionally  into  the 
substance  of  the  palate  bone.  External  to  the  irregular  orifice  of  the  sphenoidal  sinuses 
is  a  rough  surface,  which  articulates  above  with  the  lateral  masses  of  the  ethmoid,  and 
below  with  the  palate  bone.  The  orifice  of  the  sinus  is  in  a  great  measure  closed  by  a 
lamina  of  very  variable  shape,  curved  upon  itself,  and  designated  sphenoidal  turbinated,  or 
triangular  hone  {cornu  sphenoidale,  ossiculum  Bertini)  {t  t,  and  fgs.  15  and  16,  c  c).  This 
plate,  which  remains  separate  for  some  time,  appears  as  if  it  arose  from  the  upper  part 
of  the  palate  bone,  and  formed  the  anterior  and  part  of  the  inferior  wall  of  the  sinus.  It 
is  not  unusual  to  find  it  united  either  to  the  palate  bone  or  to  the  ethmoid. 

The  posterior  or  occipital  surface  {u,fig.  13)  is  quadrilateral,  rugged,  and  irregular ;  it 
articulates  with  a  corresponding  surface  on  the  basilar  process  of  the  occipital  bone,  by 
means  of  a  cartilage,  which  is  very  early  ossified.  On  the  posterior  aspect  of  the  bone  is 
situated  the  posterior  orifice  of  the  vidian  canal. 

The  lateral  surfaces  of  the  body  of  the  sphenoid  pass  into  the  base  of  the  great  icings, 
which  we  shall  next  describe. 

Great  or  temporal  wings  {y  z).  This  portion  of  the  bone  consists  of  two  large  triangu- 
lar prolongations,  on  which  there  are  three  surfaces  :  a  superior,  an  anterior,  and  an  in- 
ferior ;  two  borders,  an  external  and  an  internal ;  and  two  extremities,  an  anterior  and  a 
posterior. 

Superior  or  cerebral  surface  (y  2  z).  This  surface,  which  forms  part  of  the  middle  fossa 
of  the  base  of  the  cranium,  is  concave,  quadrilateral,  and  marked  by  cerebral  impressions 
and  vascular  furrows.  Towards  its  inner  part,  and  proceeding  from  before  backward, 
we  observe,  1.  The  superior  maxillary  forameii  (3),  or  foramen  rotundum,  directed  obliquely 
forward  and  outward,  which  gives  passage  to  the  superior  maxillary  nerve.  2.  The  in- 
ferior maxillary  foramen,  or  foramen  ovale  (4),  which  perforates  the  bone  directly  from 
above  downward,  and  transmits  the  inferior  maxillary  nerve.  3.  The  foramen  spinosum, 
or  spheno-spinosum  (5),  which  is  the  smallest  of  the  whole,  and  gives  passage  to  the  mid- 
dle meningeal  artery. 

External  or  temporo-zygomatic  surface.  This  surface  is  divided  into  two  parts  by  a 
transverse  ridge ;  the  superior  or  temporal  {l,Jig- 14)  forms  part  of  the  fossa  of  the  same 
name,  and  gives  attachment  to  the  temporal  muscle  ;  the  inferior  (p)  fonns  the  upper 


SPHENOID   BONE.  ^ 

part  of  the  zygomatic  fossa,  and  gives  attachment  to  the  external  pterygoid  muscle.    On 
this  last  part  we  perceive  the  inferior  orifices  of  the  oval  and  spinous  foramina. 

Anterior  or  Orbital  Surface. — This  surface  {w  w)  is  four-sided  and  smooth,  and  forms  the 
greater  part  of  the  external  wall  of  the  orbit.  Its  superior  border  unites  with  the  frontal 
bone  ;  the  inferior  forms  part  of  the  spheno-maxillary  fissure.  The  internal  border  con- 
tributes to  form  the  sphenoidal  fissure,  and  has  a  small  tubercle  near  its  inner  termina- 
tion.    The  external  joins  the  malar  bone. 

Internal  Border. — This  border  is  convex,  and  commences  in  front  by  a  triangular  and 
very  rough  surface  (y  y,fig.  13),  which  articulates  with  a  corresponding  surface  on  the 
frontal  bone  ;  it  then  forms  part  of  the  sphenoidal  fissure  (2),  and  finally  bends  outward 
to  join  the  petrous  portion  of  the  temporal  bone  :  in  this  place  it  is  grooved  for  the  lodg- 
ment of  the  cartilaginous  portion  of  the  Eustachian  tube.  The  sphenoidal  fissure,  or 
foramen  lacerum  superius  (2  2,  figs.  13  and  14),  partly  formed  in  the  way  we  have  described, 
is  completed  by  the  lesser  wing  of  the  sphenoid.  Wide  at  its  internal  extremity,  it  be- 
comes narrow  at  its  outer  end,  where  it  is  closed  by  the  frontal  bone  at  o.  It  gives  pas- 
sage to  the  third,  fourth,  the  ophthalmic  branch  of  the  fifth,  and  the  sixth  pair  of  nerves, 
to  the  ophthalmic  vein,  and  to  a  prolongation  of  the  dura  mater.  At  the  internal  extremity 
of  the  fissure  there  is  a  furrow,  which  is  occasionally  converted  into  a  foramen  for  the  pas- 
sage of  a  recurrent  branch  of  the  ophthalmic  artery,  which  goes  to  the  dura  mater. 

The  external  border  is  concave,  bevelled  on  the  outside  superiorly,  and  on  the  inside 
inferiorly,  for  articulation  with  the  temporal  bone. 

The  anterior  extremity  is  very  thin  (behind  y,  fig.  13),  and  bevelled  on  the  inner  side  for 
articulation  with  the  anterior  and  inferior  angle  of  the  parietal. 

The  posterior  extremity  presents  a  vertical  process  (z),  the  spine  or  spinous  process  of 
the  sphenoid,  which  is  received  into  the  angle  formed  by  the  union  of  the  squamous  and 
petrous  portions  of  the  temporal  bone,  and  gives  attachment  to  the  internal  lateral  liga- 
ment of  the  inferior  maxilla,  and  the  external  or  anterior  muscle  of  the  maUeus. 

Connexions. — The  sphenoid  articulates  with  all  the  bones  of  the  cranium,  and  with 
the  palatine,  vomer,  and  malar  bones  of  the  face. 

Structure. — The  most  remarkable  circumstance  in  the  structure  of  the  sphenoid  is  the 
presence  of  the  sinuses,  which  convert  the  body  of  the  bone  into  two  or  more  cells  (5, 
fig.  22).  The  compact  tissue  prevails  in  the  lesser  and  the  greater  wings,  and  in  the 
pterygoid  processes,  the  thick  part  only  of  these  containing  spongy  substance. 

Development. — In  the  foetus,  as  we  have  already  mentioned,  the  sphenoid  is  divided 
into  two  quite  distinct  parts:  1.  An  anterior  sphenoid,  consisting  of  the  lesser  wings 
and  the  portion  of  the  body  which  supports  them  ;  and,  2.  A  posterior  sphenoid,  formed 
of  the  great  wings  and  the  part  of  the  body  which  corresponds  to  the  sella  turcica. 

1.  The  anterior  sphenoid  is  developed  from  four  points  of  ossification;  two  for  the 
body,  and  two  for  the  alae  minores.* 

2.  The  posterior  sphenoid  is  also  developed  from  four  points ;  two  for  the  body,  and 
two  for  the  great  wings. 

Besides  these  eight  points,  there  are  two  others  on  each  side ;  one  for  the  internal 
plate  of  the  pterygoid  process,  and  one  for  the  sphenoidal  turbinated  bone  ;  so  that  the 
whole  number  of  centres  of  ossification  of  the  sphenoid  is  twelve. 

The  osseous  points  of  the  great  wings  are  the  first  to  appear ;  they  are  visible  from 
the  fortieth  to  the  forty-fifth  day ;  a  short  time  afterward,  those  of  the  lesser  wings, 
which  are  situated  on  the  outside  of  the  optic  foramen.  At  the  end  of  the  second  month 
the  osseous  points  of  the  body  of  the  posterior  sphenoid  are  distinct ;  at  the  end  of  the 
third  month,  those  of  the  body  of  the  anterior  sphenoid,  and  the  internal  pterygoid  plates  : 
the  sphenoidal  turbinated  bones  begin  to  ossify,  according  to  Beclard,  in  the  seventh 
month  of  intra-uterine  life  ;  according  to  Bertin,  in  the  second  year  after  birth. 

The  two  points  of  the  body  of  the  posterior  sphenoid  are  united  from  the  third  to  the 
fourth  month ;  the  great  wings  are  joined  to  the  body  in  the  course  of  five  or  six  months 
after  birth.  The  two  points  of  the  body  of  the  anterior  sphenoid  are  joined  to  those  of 
the  small  wings  about  the  third  or  fourth  month  ;  they  then  unite  together  in  the  me- 
dian plane  from  about  the  eighth  to  the  ninth  month.  The  union  of  ttie  internal  ptery- 
goid plates  takes  place  during  the  sixth  month,  t  The  anterior  and  posterior  sphenoid 
are  united  from  the  eighth  to  the  ninth  month.  The  sphenoidal  turbinated  bones  are 
not  joined  to  the  body  of  the  bone  until  from  the  fifteenth  to  the  eighteenth  year.  The  other 
changes  which  the  sphenoid  afterward  undergoes  are  connected  with  the  development  of 
the  sinuses.  It  is  united  with  the  occipital  bone  from  the  eighteenth  to  the  twenty-fifth  year. 

*  According  to  Albinns,  the  anttnor  spheaoid  is  formed  exclusively  by  the  union  of  tho  osseous  points  of 
the  lesser  wings  in  the  median  line.  B6clard  observes,  that  the  process  takes  place  sometimes  as  descnbed 
by  Albinus,  but  that  occasionally  there  is  a  median  point ;  and  that  at  other  times  there  are  two  points  for  each 
of  the  smaller  wings,  the  internal  of  wliich  forms  the  base  of  the  process,  and  the  inner  half  of  the  optic  fora- 
men; and  the  external  forms,  the  remainder  of  the  wing.  These  are  the  two  points  which  I  conceive  to  form 
the  body  of  the  anterior  sphenoid.  The  very  numerous  osseous  points  which  some  anatomists  have  described 
are  nothing  more  than  irregular  grains,  which  have  been  mistaken  for  constant  centres  of  ossification. 

t  In  the  lower  animals  the  two  sphenoid  bones  remain  separate  during  the  whole  ot  life.  The  inner  plate 
of  the  pterygoid  process  is  also  a  distinct  bone. 


40  OSTEOLOGY. 

The  Ethmoid  Bone  (figs.  15  and  16). 

The  ethmoid  is  so  named  from  the  Greek  word  r/Ofibc,  a  sieve,  because  it  is  perfoj-ated 
with  a  number  of  foramina ;  it  is  placed  in  the  anterior  and  middle  part  of  the  base  of 
the  cranium,  but  belongs  rather  to  the  face  and  nasal  fossse.  It  is  included  between  the 
median  notch  of  the  orbital  part  of  the  frontal  and  the  sphenoid.  It  is  a  symmetrical 
bone  of  a  cuboidal  figure,  consisting  of  three  parts— a  middle  part  or  cribrifmm  plate,  and 
two  lateral  masses. 

Cribriform  Plate. — This  is  a  lamina  situated  on  the  median  line,  horizon- 
tal, quadrilateral,  and  pierced  with  numerous  foramina.  It  has  two  surfa- 
ces, and  two  borders.  On  the  superior  surface  («  a,  fig.  15)  we  observe  in 
the  middle  a  vertical  triangular  process,  the  crista  galli  (i  and  n,  fig.  22) ; 
the  summit  of  this  eminence  gives  attachment  to  the  fabc  cerebri ;  the  an- 
terior border  terminates  in  front  in  two  small  processes  {alee)  (/),  which 
articulate  with  the  frontal  bone,  and  often  complete  the  foramen  caecum ; 
the  posterior  border  is  very  oblique,  and  is  continued  to  the  posterior  edge 
of  the  cribriform  plate  by  a  marked  thickening.  There  are  many  varia- 
tions in  the  size  and  direction  of  this  process  :  it  is  frequently  deflected  to 
one  side.*  On  each  side  is  the  ethmoidal  groove  (a),  deeper  and  narrower  in  front  than 
behind ;  it  is  pierced  throughout  its  whole  extent  with  numerous  foramina,  which  have 
been  very  accurately  described  by  Scarpa,  and  which  form  two  rows  ;  the  internal,  sit- 
uated along  the  base  of  the  crista  galli,  being  the  largest.  They  all  transmit  filaments 
of  the  olfactory  nerves ;  they  are  funnel-shaped,  and  are  the  orifices  of  canals,  which 
subdivide  in  traversing  the  cribriform  plate,  and  terminate  in  grooves,  either  upon  the 
turbinated  bones  or  the  perpendicular  plate  of  the  ethmoid.  Among  these  openings  is 
one  which  has  the  form  of  a  longitudinal  fissure  by  the  side  of  the  crista  galli,  and  trans- 
mits the  ethmoidal  or  nasal  branch  of  the  ophthalmic  nerve. 

The  inferior  surface  of  the  cribriform  plate  (fig.  16)  forms  part  of  the  roof  of  the  nasal 

Fig.  16.        fossa; ;  it  presents  on  the  median  line  a  vertical  plate  {g  g,fig.  16),  which 

'  y'        passes  from  before  backward,  and  divides  it  into  two  equal  parts.     This 

is  the  perpendicular  plate  of  the  ethmoid,  continuous  with  the  base  of  the 

crista  gaUi,  quadrilateral,  often  deflected  to  one  side,  and  forms  part  of  the 

septum  narium  (1,  2,  3,  ^,fig.  22) :  in  front,  it  articulates  with  the  nasal 

spine  of  the  frontal  bone,  and  with  the  proper  bones  of  the  nose  ;  behind, 

with  the  anterior  crest  of  the  sphenoid  ;  below,  with  the  vomer,  and  the 

cartilage  of  the  septum ;  and  above  it  is  united  to  the  cribriform  plate, 

along  the  line  of  the  crista  galli,  which  appears  to  grow  out  of  it.     The 

anterior  border  of  the  cribriform  plate  articulates  with  the  frontal.     The 

posterior  is  usually  notched  for  the  reception  of  the  spine,  or  process  (/, 

figs.  13  and  14),  which  surmounts  the  median  ridge  of  the  sphenoid. 

The  lateral  masses  are  cuboid  in  figure,  and  formed  of  large  irregular  cells,  which  to- 
gether are  named  the  labyrinth.  They  have  six  surfaces  :  in  the  superior  surface  we  ob- 
serve several  imperfect  cells  {d  d,fig.  15),  which,  in  the  united  state,  are  completed,  and, 
as  it  were,  roofed  in  by  those  we  have  already  described  as  existing  on  each  side  of  the 
ethmoidal  notch  of  the  frontal.  We  find,  also,  two  or  three  grooves,  which  join  with 
similar  grooves  in  the  frontal  bone,  and  form  the  internal  orbitary  canals.  On  the  infe- 
rior surface  we  perceive  thin,  irregularly-twisted  laminae,  which  narrow  the  opening  of 
the  maxillary  sinuses.  The  most  considerable  of  these  has  received  the  name  of  unci- 
form or  great  process  of  the  ethmoid  :  it  is  a  curved  plate  which  arises  from  the  inferior 
surface  of  the  transverse  septa,  which  close  the  anterior  ethmoidal  cells,  and  is  placed 
between  the  anterior  extremity  of  the  middle  turbinated  bone  and  the  os  planum  or  la- 
mina papyracea,  to  be  afterward  described ;  it  sometimes  articulates  with  the  inferior 
turbinated  bone.  The  anterior  surface  presents  half  cells,  which  are  covered  by  the  os 
unguis  and  the  ascending  process  of  the  maxillary  bone.  On  the  posterior  surface  we  see 
the  posterior  extremities  of  the  superior  and  middle  turbinated  bones,  and  of  the  superior 
and  middle  meatus,  and  a  convex,  uneven  surface,  which  corresponds  with  the  posterior 
ethmoidal  cells.  This  surface  articulates  with  the  sphenoid  above,  and  with  the  palate 
bone  below.  The  external  surface  is  formed  by  a  smooth,  quadrilateral  plate  {e,fig.  15), 
placed  vertically  and  very  thin,  to  which  the  ancients  gave  the  name  of  lamina  papyracea 
or  os  planum.  It  has  an  elongated,  rectangular  form,  is  slightly  curved  upon  itself,  and 
constitutes  a  great  part  of  the  internal  wall  of  the  orbit.  The  superior  border  articu- 
lates with  the  frontal,  and  assists  in  forming  the  orifice  of  the  internal  orbital  canals  : 
the  inferior  articulates  with  the  maxiUary  and  palate  bones,  the  anterior  with  the  os  un- 
guis, and  the  posterior  with  the  sphenoid  and  palate  bones. 

The  internal  surface  of  the  lateral  masses  constitutes  the  greatest  part  of  the  external 
wall  of  the  nasal  fossae  :  on  it  we  observe,  in  front,  a  rough,  quadrilateral  surface,  marked 

*  Morgagni  mentions  the  case  of  an  asthmatic  subject,  in  whom  the  crista  galli  was  so  obliquely  placed, 
that  the  ethmoidal  groove  on  one  side  was  very  much  contracted,  and  considerably  enlarged  on  the  othet 
There  was  a  much  greater  number  of  foramina  on  one  side  than  on  the  other. 


PARIETAL   BONES.  41 

by  grooves  and  canals,  which  lodge  the  ramifications  of  the  olfactory  nerve  ;  behind,  two 
thin  plates,  twisted  upon  themselves  like  certain  shells  :  they  are  the  turbinated  or  spongy 
bones  of  the  ethmoid,  or  concha  of  the  ethmoid.  The  superior  {b,  fig.  35)  is  the  smaller, 
and  is  sometimes  named  concha  of  Morgagni ;  Bertin  has  seen  it  double.  The  inferior 
{cfig.  37)  is  larger,  and  forms  the  middle  concha ;  it  articulates  by  its  posterior  extremity 
with  the  palate  bone,  and  its  superior  border  is  continuous  with  a  transverse  septum, 
which  stretches  across  to  the  lower  edge  of  the  os  planum,  and  partially  closes  the  mid- 
«lle  or  frontal  cells.  The  superior  and  middle  turbinated  bones  are  separated  by  a  hori- 
zontal groove  called  the  superior  meaius  of  the  nasal  fossae  (between  b  and  c,  fig.  37),  at 
the  superior  part  pf  which  appears  an  opening  of  communication  with  the  posterior  eth- 
moidal cells.  Below  the  middle  turbinated  bone  is  a  similar  groove  (between  c  and  d, 
fig.  37)  running  from  before  backward,  and  forming  part  of  the  middle  meatus  of  the  nose. 
Anteriorly  it  leads  into  a  cell,  the  lower  part  of  which  is  broad  and  the  upper  narrow, 
whence  it  has  received  the  name  of  infundibulum.  This  cell  communicates  directly 
with  the  frontal  sinuses,  and,  by  a  small  aperture,  with  the  anterior  ethmoidal  cells. 

Internal  Structure. — ^The  ethmoid  is  composed  of  extremely  thin  and  fragile  plates,  ar- 
ranged in  more  or  less  irregular  cells,  having  a  hexahedral,  pentahedral,  or  tetrahedral 
shape.  They  are  disposed  in  distinct  series,  which  have  no  communication  with  each 
other.  The  anterior  cells  are  the  largest  and  most  numerous  ;  they  open  into  the  mid- 
dle meatus  by  the  infundibulum ;  the  posterior'open  into  the  superior  meatus.  There 
is  a  little  spongy  substance  in  the  crista  galli,  which  is  even  sometimes  hollowed  into  a 
small  sinus  which  communicates  with  the  frontal  sinuses.  There  is  also  spongy  sub- 
stance in  the  turbinated  bones,  and  here,  by  a  remarkable  exception,  it  occupies  the 
surface.  The  specific  lightness  of  the  ethmoid  is  such  that  it  floats  in  water,  and  its  ex- 
treme brittleness  is  readily  explained  by  its  spongy  structure. 

Connexions. — The  ethmoid  is  connected  with  thirteen  bones :  the  frontal,  the  sphe- 
noid, the  ossa  unguis,  the  superior  maxillary,  the  inferior  turbinated,  the  nasal,  the  pal- 
ate bones,  and  the  vomer. 

Development. — The  ossification  of  the  ethmoid  does  not  conmience  until  the  fifth 
month.  It  begins  in  the  lateral  masses,  and  more  particularly  in  the  os  planum ;  shortly 
afterward  the  spongy  bones  make  their  appearance.  The  middle  portion  is  not  ossified 
until  after  birth.  The  crista  galli  and  the  contiguous  part  of  the  perpendicular  plate,  and 
the  cribriform  plate,  become  bony  between  the  sixth  month  and  the  first  year.  At  the 
end  of  the  first  year,  the  cribriform  plate  is  united  to  the  lateral  masses.  In  the  foetus, 
at  the  full  time,  the  lateral  masses  are  so  little  developed,  that  their  internal  and  exter- 
nal walls  are  almost  contiguous.  The  cells  are  completely  formed  about  the  fourth  or 
fifth  year. 

The  Parietal  Bones  {figs.  17  and  18). 

The  parietal  bones  are  so  called  because  they  form  the  greatest  part  of  the  s'aes  oi 
the  head.     They  are  two  in  number,  the  right  and  the 
left  ;  but  sometimes  in  the  adult  they  are  united  so  as 
to  form  only  one  bone.     They  occupy  the  summit  and 
sides  of  the  head.     In  shape  they  are  quadrilateral,  and 
much  thicker  above  than  below,  so  that  a  force  applied  u^,^ 
to  the  crown  of  the  head  often  causes  a  fracture  of  the  \i~^ 
lower  parts  of  these  bones.    The  parietal  bones  have  J' 
two  faces,  four  borders,  and  four  angles.  ^^^ 

The  external  or  cutaneous  surface  (fig.  17)  is  convex  '- 
and  smooth,  with  a  projection  in  the  centre,  the  parietal 
protuberance  (j),  which  is  more  prominent  in  the  child 
than  in  the  adult,  and  corresponds  with  the  point  where 
the  breadth  of  the  cranium  is  greatest.  Below  this 
there  is  a  semicircular  line  (g),  with  the  concavity  looking  downward,  which  forms  the 
superior  boundary  of  the  temporal  fossas,  and  gives  attachment  to  the  temporal  aponeu- 
rosis ;  the  rest  of  the  surface  below  this  curved  line  gives  attachment  to  the  fibres  of  the 
temporal  muscle.  The  rest  of  this  surface  is  covered  only  by  the  cranial  aponeurosis 
and  the  skin. 

The  internal  or  encephalic  surface  {fig.  18)  is  concave,  and  marked  with  mammillary 
projections  and  digital  impressions  ;  it  is  traversed  by  ramified  ^ooves,  resembling  the 
veins  of  a  leaf  {ff,  fig.  18),  which  converge  partly  to  the  anterior  inferior,  and  partly  to 
the  posterior  inferior  angle  of  the  bone,  and  correspond  to  the  branches  of  the  menin- 
geal artery.  The  parietal  fossa,  a  concavity  corresponding  to  the  prominence  of  the  same 
name,  is  situated  in  the  middle  of  this  surface. 

The  superior  or  sagittal  border  (  a  b,fig.  17  and  18)  is  the  longest :  it  is  thick  and  den- 
ticiUated,  and,  by  its  union  with  the  opposite  bone,  forms  the  sagittal  suture.  On  its  in- 
ternal surface  there  is  a  furrow  along  its  whole  extent,  which,  with  that  in  the  oppo- 
site bone,  forms  the  groove  for  the  longitudinal  sinus.     Near  this  border  is  sometimes 

F 


OSTEOLOGY. 


found  a  foramen  (c)  {foramen  parietalc),  of  very  varia- 
ble dimensions,  which  opens  into  the  posterior  part  of 
the  groove,  and  transmits  a  vein  which  is  sometimes 
very  large.  We  may  farther  state,  that  along  this  sur- 
face the  impressions  made  by  the  pacchionian  glands 
are  to  be  observed.  They  are  more  remarkable  in  the 
old  than  young  subject. 

The  inferior  or  temporal  border  {d  e)  is  the  shortest : 
it  is  concave,  thin,  and  very  obliquely  cut  on  the  out- 
side, so  as  to  resemble  a  scale  with,  radiated  furrows  ; 
hence  its  name  {margo  squamosus) :  it  articulates  with 
the  squamous  portion  of  the  temporal  bone. 

The  anterior  or  frontal  border  {b  e)  is  less  thick  and 
less  deeply  indented  than  the  occipital  edge  :  it  is  bev- 
elled externally  above,  and  internally  below,  so  as  to  articulate  with  the  frontal  bone, 
which  presents  a  precisely  opposite  arrangement. 

The  posterior  or  occipital  border  (a  d)  is  very  deeply  indented,  and  articulates  with  the 
superior  border  of  the  occipital  by  the  lambdoid  suture.  Of  the  four  angles,  the  two  supe- 
rior are  right  angles ;  of  the  inferior,  the  anterior  or  sphenoidal  (e)  is  acute,  and  rendered 
very  thin  by  the  sloping  of  the  anterior  and  inferior  edges  of  the  bone.  Inside  this  angle 
is  situated  the  principal  furrow,  or  sometimes  canal,  which  lodges  the  middle  meningeal 
artery  and  veins  :  surgeons,  therefore,  recommend  this  angle  to  be  avoided  in  perfonning 
the  operation  of  trepanning.  The  posterior  or  mastoid  angle  (d)  is,  as  it  were,  truncated, 
and  is  received  mto  the  retreating  angle  formed  by  the  union  of  the  mastoid  and  squa- 
mous portions  of  the  temporal  bone.  Internally,  it  is  grooved  for  the  reception  of  part 
of  the  lateral  sinus  (e,  fig.  22). 

Connexions. — Tlie  parietal  is  articulated  with  five  bones  :  the  frontal,  the  occipital,  the 
temporal,  the  sphenoid,  and  the  opposite  parietal  Above,  it  is  separated  from  the  skin 
by  the  cranial  aponeurosis  only,  and  consequently  it  exposes  a  large  extent  of  surface 
to  the  action  of  external  agents  :  hence  fractures  of  this  bone  are  very  common,  and 
they  are,  more  frequently  than  other  fractures,  accompanied  by  effusions  of  blood,  on 
account  of  the  connexion  with  the  middle  meningeal  artery  and  vein. 

The  internal  structure  is  quite  similar  to  that  of  the  frontal.  In  that  bone  we  find 
venous  canals  traversing  long  tracts  in  the  substance  of  the  diploe. 

Development. — The  parietal  bone  is  developed  from  one  point  of  ossification  alone, 
which  appears  in  the  situation  of  the  protuberance.  Its  firet  traces  are  observed  about 
the  forty-fifth  day.  The  angles  are  the  last  parts  of  the  bone  which  are  developed :  their 
absence  gives  rise  to  the  fontanelles  of  the  cranium. 

The  Temporal  Bones  [jigs.  19  and  20). 

The  temporal  bones  are  so  called  from  being  situated  in  the  locality  of  the  temples. 

They  are  two  in  number,  and  occupy  part  of  the  sides  and  base  of  the  cranium,  below 

the  parietal  bones,  above  the  inferior  maxillary,  in  front  of  the  occipital,  and  behind  the 

sphenoid.    The  temporal  bone  contains  the  complicated  apparatus  of  the  organ  of  hearing. 

Its  figure  is  veiy  irregular,  and  therefore,  in  order  to  facilitate  the  description,  we  shall 

consider  it  as  divided  into  three  parts,  the  squamous,  the  mastoid,  and  the  petrous  portions. 

Squamous  portion. — The  squamous  portion  has  the  form  of  a  semicircular  scale  (a  b  c, 

Jigs.  19  and  20),  bearing  a  considerable  resemblance  to 

one  of  the  valves  of  certain  shell-fish :  it  occupies  the 

anterior  and  superior  part  of  the  bone.     It  is  by  far  the 

thinnest  part  of  the  cranium ;  and  hence  the  common 

but  well-founded  notion  of  the  danger  of  blows  upon 

the  temple,  although  this  danger  is  much  lessened  by 

the  presence  of  the  zygomatic  arch  and  the  temporal 

^^  muscle. 

The  external  surface  (/,  fig.  19)  forms  part  of  the 
temporal  fossa :  it  is  smooth,  convex,  and  marked  by 
vascular  furrows.  At  its  lower  portion  is  situated  the 
zygomatic  process  (m  n)  {^evyvvu,  I  join),  so  called  be- 
cause it  unites  the  sides  of  the  cranium  to  the  face  :  it 
is  also  named  a-iisa  capitis,  and  is  one  of  the  longest 
processes  of  the  skeleton.  At  its  origin  it  is  broad  and  directed  outward  ;  it  then  grad- 
ually diminishes  in  size,  and  bends  so  as  to  turn  horizontally  forward  and  a  little  out- 
ward :  it  is  flattened  from  without  inward.  The  external  surface  is  convex,  and  may 
be  easily  traced  under  the  skin  ;  the  internal  surface  is  concave  ;  the  superior  border, 
which  gives  attachment  to  the  aponeurosis  of  the  temporal  muscle,  convex  and  thin ; 
the  inferior,  which  gives  origin  to  the  meisseter  muscle,  concave,  thick,  and  much  shorter ; 
and  the  extremity  (m)  is  cut  from  below  upward  and  forward,  and  denticulated  for  attach 
ment  Avith  a  corresponding  surface  on  the  malar  bone.     The  base  of  this  process  is 


TEMPORAL    BONES.  43 

grooved  above,  and  serves  as  a  julley  for  the  reflection  of  piart  of  the  temporal  muscle. 
Posteriorly,  it  separates  into  two  portions  or  roots :  the  inferior  (o)  of  these  is  the  larger ; 
it  is  transverse,  covered  with  cartilage,  and  bounds  the  glenoid  cavity  in  front,  serving 
also  to  increase  the  articular  surface  in  the  joint  of  the  lower  jaw.  The  superior  (?i)  is 
longitudinal  or  antero-posterior  in  its  direction  :  it  also  is  bifurcated,  one  branch  directed 
upward,  and  forming  part  of  the  temporal  semicircular  line,  the  other  passing  between 
the  auditory  meatus  and  the  glenoid  cavity.  At  the  point  of  junction  of  the  two  roots 
there  is  a  tubercle,  which  gives  insertion  to  the  external  lateraUigament  of  the  lower  jaw. 
Between  the  two  roots  we  observe  the  glenoid  cavity  (behind  flitaivided  into  two  portions  ; 
the  anterior  of  which  is  articular,  smoothjand  in  the  fresh  state  covered  with  cartilage  ; 
the  posterior  (s)  does  not  enter  into  the  fOTfflation  of  the  joint.  The  parts  are  separated 
by  a  fissure,  called  glenoidal  fissure,  or  fissure  of  Glasserius  (before  s),  which  transmits  the 
corda  tyrapani  nerve,*  the  laxator  %mpani  or  external  muscle  of  the  malleus,  the  inter- 
nal auditory  vessels,  and  lodges  the  processus  gracilis  of  the  malleus  {process  of  Raw). 

The  internal  surface  of  the  squamous  portion  (g,  fig.  20)  presents  a  concavity  propor- 
tionally greater  than  the  convexity  on  the  outside :  it  is 
marked  by  the  ordinary  inequalities,  and  is  generally  trav- 
ersed, towards  the  upper  part,  by  a  horizontal  vascular  fur- 
row, running  from  before  backward. 

The  circumference  (a  h  c)  forms  about  three  fourths  of  a  cir- 
cle ;  it  is  very  obliquely  cut  internally  in  its  two  posterior 
thirds,  which  unite  with  the  parietal ;  the  anterior  third  is 
thicker,  and  bevelled  externally :  it  unites  with  the  sphenoid. 

Mastoid  Portion  (c  e  d,figs.  19  and  20). — ^The  mastoid  por- 
tion is  very  prominent  in  adults,  but  only  slightly  developed 
in  young  subjects  :  it  occupies  the  posterior  and  inferior 
part  of  the  bone. 

The  external  surface  {fig.  19)  is  convex  and  rough,  ter- 
minating below  and  in  front  in  a  nipple-shaped  process,  the 
mastoid  process  (e).  Inside  of  this  is  a  deep  gi'oove  called  digastric  (fossa  digastrica), 
because  it  gives  origin  to  the  muscle  of  that  name.  Behind  the  mastoid  process  we  observe 
the  mastoid  foramen,  an  opening  which  transmits  the  mastoid  artery  and  vein,  but  which 
is  subject  to  numerous  varieties  in  its  size  and  position.  Above  the  process  is  a  rough 
surface,  for  muscular  attachments  of  the  splenius  and  sterno-cleido  mastoideus  muscles. 

The  internal  surface  is  concave,  and  forms  part  of  the  lateral  and  posterior  fossae  of  the 
cranium  ;  we  observe  on  this  surface  a  deep  and  broad  semi-cylindrical  groove  {h  i,  fig. 
20),  which  lodges  the  greater  portion  of  the  lateral  sinus.  At  the  bottom  of  this  gi'oove 
the  mastoid  foramen  opens  by  one  or  more  apertures.  There  is  generally  a  considerable 
difTerence  in  size  between  the  grooves  on  the  right  and  left  side  of  the  head. 

The  circumference,  very  thick  and  indented,  unites  in  front  with  the  circumference  of 
the  squamous  portion,  forming  a  retiring  angle  (c),  which  is  occupied  by  the  posterior 
inferior  angle  of  the  parietal  bone,  and  then  curves  round  in  a  semicircle  to  join  the 
occipital  bone  by  means  of  a  thick,  uneven  edge. 

Petrous  Portion ;  Rocher  or  Pyramid  {ci  dv,  fig.  20)  Petrous  Process. — This  part  of  the 
bone  is  placed  between  the  squamous  and  mastoid  portion,  resembling  a  pyramid,  pro- 
jecting forward  and  inward  into  the  cavity  of  the  cranium.  Its  name  sufficiently  indi- 
cates the  extreme  hardness  of  its  osseous  structure  :  a  circumstance  very  important  in 
relation  to  its  functions  (for  this  part  of  the  bone  serves  as  the  receptacle  of  the  vibratory 
apparatus  of  the  ear),  and  at  the  same  time  is  calculated  to  explain  the  frequency  of  frac- 
tures in  this  situation.  It  has  the  form  of  a  truncated  pyramid  with  three  faces,  separated 
by  three  borders. 

The  inferior  surface,  which  is  seen  at  the  base  of  the  cranium,  is  very  irregular,  and 
presents  the  following  objects,  in  an  order  from  without  inward:  1.  A  long,  slender 
process  (k),  generally  from  twelve  to  fifteen  lines,  sometimes  two  inches  in  length. 
This  process,  which  hcis  been  denominated  styloid,  is,  in  man,  usually  continuous  with 
the  rest  of  the  bone,  but  occasionally  it  is  articulated  by  a  movable  joint,  as  in  the  lower 
animals,  where  it  is  always  separate,  and  is  known  by  the  name  of  styloid  hone. 

2.  Behind  this  process,  between  it  and  the  mastoid,  is  a  sort  of  fossa,  at  the  bottom 
of  which  we  find,  besides  one  or  two  accessory  foramina,  the  stylo-mastoid  foramen  (y,  fig- 
21),  which  forms  the  inferior  aperture  of  a  canal  improperly  called  the  aqueduct  of  Folio- 
pius,i  which  transmits  the  facial  nerve.  3.  Inside  of  the  styloid  process  and  the  stylo- 
mastoid foramen  is  a  triangular  surface  called  the  jugular,  which  joins  with  a  correspond- 
ing part  of  the  occipital  bone.  4.  A  little  within  and  behind  the  styloid  process  is  a  deep 
depression,  which  forms  part  of  the  jugular  fossa,  and  lodges  the  enlarged  commence- 
ment or  sinus  of  the  jugular  vein.  5.  The  inferior  orifice  of  the  carotid  canal  (»,  fig.  21), 
Which  is  directed  at  first  vertically,  then  horizontally,  nmning  forward  and  inward,  and 

*  [The  corda  tympani,  according  to  the  author,  passes  through  a  special  orifice  by  the  side  of  the  glenoid 
fissure.     See  description  of  the  ear,  in/rd.] 
i  [Fallopius  knew  that  this  canal  transmitted  a  nerve;  he  named  it  aqueduct  merely  on  account  of  its  direction.] 


44  OSTEOLOGY. 

again  vertically  at  its  termination  in  the  cavity  of  the  cranium.  6.  A  rough  surface, 
which  gives  attachment  to  the  levator  palati  muscle.  Lastly,  in  front  of  the  styloid 
process  is  an  osseous  lamma,  in  the  form  of  a  vertical  crest  {s,fig.  19),  a  continuation  of 
the  plate  which  forms  both  the  inferior  portion  of  the  auditory  canal,  and  the  posterior 
portion  of  the  glenoid  cavity,  which  it  completes.  This  crest,  which  has  been  described 
by  authors  under  the  name  of  vaginal  process,  because  it  surrounds  the  styloid  process 
without  adhering  to  it,  extends  inward  to  form  part  of  the  carotid  canal,  and  outward  to 
the  mastoid  process. 

The  other  two  surfaces^  the  petrous  portion,  of  which  one  is  superior  and  the  other 
posterior,  are  in  the  interior  of  the  cranium. 

The  superior  surface,  which  looks  forward,  has  a  furrow  running  from  before  backward 
and  from  below  upward,  terminating  about  llie  middle  of  the  surface  in  a  small  iiTcgular 
opening,  the  hiatus  Fallopii,  which  communicates  "^jith  the  aqueduct  of  Fallopiu^.  The 
furrow  and  the  hiatus  contain  the  superior  or  cranial  filament  of  the  vidian  nerve,  and  a 
small  artery. 

The  posterior  surface  shows  a  canal  directed  obliquely  from  within  outward  and  for- 
ward. This  is  the  internal  auditory  meatus  {I,  fig.  20) ;  it  is  shorter  than  the  external, 
and  is  terminated  by  a  lamina  divided  into  two  parts  by  a  transverse  ridge  ;  in  the  supe- 
rior of  these  parts  there  is  a  single  orifice,  the  commencemnet  of  the  aqueduct  of  Fallopius, 
which  receives  the  facial  nerve  ;  the  inferior  is  perforated  by  numerous  openings,  through 
which  the  fibres  of  the  auditory  nerve  pass ;  it  is  the  cribriform  plate  of  the  auditory 
nerve.  Behind  the  internal  auditory  meatus  is  a  small  opening,  which  is  the  orifice  of 
a  canal  named  aqueductus  vestibuli. 

These  surfaces  of  the  petrous  process  are  separated  by  three  borders. 

On  the  superior  border  (m  v)  we  observe  a  furrow  for  the  superior  petrosal  sinus  ;  cdso 
a  projection  which  corresponds  with  the  superior  semicircular  canal  of  the  internal  ear, 
and  which  is  most  prominent  in  the  young  subject ;  inside  of  this  projection,  a  cavity, 
the  depth  of  which  is  in  the  inverse  ratio  of  the  age,  and  is  gradually  obliterated  in  the 
adult,  and  near  the  summit  a  depression,  on  which  the  fifth  or  trifacial  nerve  rests. 

The  anterior  or  sphenoidal  border,  in  the  external  half  of  its  extent,  is  connected  with 
the  squamous  portion  of  the  bone  ;  at  first  by  a  suture  which  often  remains  perfect  even 
in  adult  life,  and  subsequently  in  a  great  measure  disappears,  but  is  never  completely 
obliterated.  The  internal  half  is  free,  and  forms,  by  its  union  with  the  squamous  portion, 
a  retiring  angle,  at  the  apex  of  which  are  the  openings  of  two  canals,  placed  parallel, 
like  the  barrels  of  a  double-barrelled  gun,  and  separated  by  a  small  osseous  lamina.  The 
superior  canal,  much  the  smaller,  contains  the  internal  muscle  of  the  malleus ;  the  in- 
ferior canal  forms  the  osseous  portion  of  the  Eustachian  tube.  They  both  communicate 
with  the  cavity  of  the  tympanum ;  the  bony  lamella,  which  separates  them,  is  called  the 
cochleariform  process. 

The  inferior,  posterior,  or  occipital  border,  rough,  but  without  indentations,  is  united  to 
the  occipital  bone  by  juxtaposition.  It  has  a  deep  notch,  which  forms  part  of  ihe  fora- 
men lacerum  posterius.  This  notch,  which  is  continuous  with  the  jugular  fossa,  already 
described,  is  frequently  divided  into  two  portions  by  a  tongue  of  bone,  one  being  anterior, 
the  other  posterior.  Immediately  in  front  of  the  notch  is  a  small  triangular  opening, 
the  inferior  orifice  of  the  aqueduct  of  the  cochlea. 

On  the  base  (fig.  19),  which  is  not  distinct  from  the  rest  of  the  bone,  the  only  part  to 
be  noticed  is  the  external  auditory  meatus  {y),  which  is  situated  behind  the  glenoid  cavity. 
It  is  rough  infeiiorly  for  the  insertion  of  the  cartilage  of  the  ear ;  and  the  canal,  which 
is  more  contracted  in  the  middle  than  at  either  extremity,  takes  a  curved  direction,  the 
concavity  looking  downward  and  forward :  it  is  chiefly  formed  by  a  curved  plate,  named 
the  auditory  process,  which  constitutes  the  posterior  half  of  the  glenoid  cavity. 

The  summit  of  the  pars  petrosa  (»,  fig.  20)  is  very  irregular  and  truncated :  it  presents 
the  superior  orifice  of  a  carotid  canal,,  and  forms  part  of  the  foramen  lacerum  anterius. 

Connexions. — The  temporal  articulates  with  five  bones,  viz.,  three  of  the  cranium,  the 
parietal,  occipital,  and  sphenoid ;  and  two  of  the  face,  the  malar  and  the  inferior  maxil- 
lary ;  we  might  add,  also,  the  os  hyoides,  which  is  attached  by  a  ligament  to  the  styloid 
process. 

Internal  Structure. — The  squamous  portion  is  compact  throughout,  excepting  towards 
the  circumference,  where  traces  of  diploe  may  be  seen.  The  petrous  portion  is  still 
more  compact  and  hard,  resembling  in  density  the  teeth,  or  certain  ivory-like  exostoses. 
The  mastoid  portion  is  hollowed  out  into  large  cells,  and  is  very  liable  to  be  affected  by 
caries.  In  the  description  of  the  orga7i  of  hearing  we  shall  notice  the  cavities  which  ex- 
ist in  the  petrous  portion ;  the  nervous  and  vascular  canals  will  be  described  with  the 
nerves  and  vessels  which  traverse  them.  (For  the  aqueduct  of  Fallopius,  see  the  de- 
scription of  the  Facial  Nerve.) 

Development. — The  temporal  bone  is  developed  from  five  points  of  ossification :  the 
squamous,  petrous,  and  mastoid  portions,  the  auditory  canal,  and  the  styloid  process, 
being  each  distinct.  The  first  osseous  point  which  appears  is  situated  in  the  squamous 
portion,  and  is  visible  towards  the  end  of  the  second  month.    Immediately  afterward 


THE    CRANIUM    IN    GENERAL..  45 

tho  petrous  portion  exhibits  a  bony  nucleus,  stretching  from  its  base  towards  its  apex. 
The  third  point  in  order  is  that  of  the  circle  of  the  tympanum,  a  kind  of  ring  channelled 
all  round  for  the  membrana  tympani.  This  circle,  at  first  almost  horizontal,  becomes 
gradually  more  and  more  oblique  ;  it  is  incomplete  above,  and  the  two  extremities  which 
are  applied  to  the  squamous  portion  cross  each  other  instead  of  uniting.  In  many  ani- 
mals the  ring  of  the  tympanum  constitutes  a  distinct  bone,  named  the  lym-panic  heme. 
The  fourth  point  of  ossification  appears  in  the  mastoid  portion  during  the  fifth  month. 
The  last  which  becomes  visible  is  that  of  the  styloid  process :  it  also  remains  distinct 
throughout  life  in  the  lower  animals,  and  is  called,  the  styloid  lone.  It  is  not  uncommon 
to  find  it  in  the  same  condition  in  the  human  subj'ect. 

The  development  of  these  five  pieces  does  not  advance  with  equal  rapidity.  The 
petrous  portion  is  most  quickly  completed.  The  mastoid,  squamous,  and  petrous  por- 
tions become  united  during  the  first  year.  The  styloid  process  is  attached  to  the  rest 
of  the  bone  at  the  age  of  two  or  three  years  ;  at  birth,  the  glenoid  cavity  is  almost  flat, 
on  account  of  the  absence  of  the  auditory  canal,  and  the  slight  development  of  the  trans- 
verse root  of  the  zygomatic  process.  The  ulterior  changes  which  take  place  in  the 
temporal  bone  depend  on  the  completion  of  the  auditory  canal  and  glenoid  cavity,  the 
increasing  size  of  the  mastoid  process,  and  the  obliteration  of  the  projections  and  filling 
up  of  the  hollows  on  the  surface  of  the  petrous  portion. 

It  is  worthy  of  remark,  that  traces  of  the  union  of  the  base  of  the  petrous  portion 
with  the  squamous  and  mastoid  portions,  are  visible  in  individuals  of  the  most  advan- 
ced age. 

The  Cranium  in  general. 

The  different  bones  which  we  have  described  unite  in  forming  the  cranium,  an  osse- 
ous cavity  which  encloses  the  brain,  the  cerebellum,  and  the  annular  protuberance.  It 
is  situated  above  the  face,  is  the  most  elevated  portion  of  the  skeleton,  and  forms  a  con- 
tinuation of  the  vertebral  column.  "The  form  of  the  cranium  is  that  of  an  ovoid,  flatten- 
ed below  and  at  the  sides,  and  with  the  large  extremity  turned  backward.  It  is  never 
perfectly  synametrical ;  but  a  very  great  deviation  has  always  appeared  to  me  coincident 
with  disease  of  the  brain.  From  attentive  examination  of  a  great  number  of  sculls  of 
idiots  and  maniacs,  I  have  observed  that  in  these  subjects  there  is  a  remarkable  differ- 
ence between  the  two  sides. 

The  dimensions  of  the  cranium  have  been  very  accurately  determined  by  Bichat.  The 
antero-posterior  diameter,  measured  from  the  foramen  caecum  to  the  occipital  protuber- 
ance, is  about  five  inches  ;*  the  transverse  diameter,  measured  between  the  base  of  the 
petrous  portions  of  the  temporal  bones,  is  four  inches  and  a  half ;  the  vertical  diameter, 
extending  from  the  anterior  edge  of  the  foramen  magnum  to  the  middle  of  the  sagittal 
suture,  is  rather  less  than  the  transverse.  In  front,  and  behind  the  spot  where  the 
height  and  breadth  of  the  cranium  are  measured,  i.  e.,  in  front  and  behind  the  bases  of 
the  petrous  bones,  the  diameters  progressively  diminish.  Hence  it  follows,  that  the 
point  where  the  cranium  has  the  greatest  capacity  is  the  junction  of  the  two  anterior 
thirds  with  the  posterior  third  ;  that  is  to  say,  at  the  place  of  meeting,  or,  if  I  may  use 
the  expression,  at  the  confluence  of  the  brain,  cerebellum,  and  spinal  marrow. 

The  cranium,  however,  presents  many  varieties,  both  in  regard  to  its  dimensions  and 
shape.  The  varieties  of  form  of  the  scull  in  different  individuals  appear  generally  to  de- 
pend upon  the  preponderance  of  one  diameter  over  another ;  and  it  may  be  remarked, 
that  in  these  cases,  where  one  diameter  is  much  increased,  the  others  are  almost  in- 
variably diminished  in  the  same  proportion,  so  that  the  absolute  difference  in  size  is  by 
no  means  considerable. 

There  are  also  variations  in  size  and  figure  peculiar  to  the  crania  of  different  nations, 
as  has  been  shown  by  the  researches  of  Blumenbach  and  Scemmerring.  In  the  white, 
or  Caucasian  race,  the  cranium  is  decidedly  much  larger  than  in  the  others,  more  es- 
pecially than  in  the  negro.  Among  certain  tribes,  the  configuration  of  the  cranium  is 
determined  by  the  permanent  or  frequently-repeated  compressions  to  which  the  sculls 
of  infants  are  subjected.  It  varies  also  according  to  age  and  sex,  being  proportionally 
larger  in  the  foetus  than  in  the  adult,  and  in  the  male  than  in  the  female.  It  should  be 
remarked  that  all  these  varieties  are  exclusively  confined  to  the  vault  of  the  cavity. 
Since  the  cranium  is  exactly  moulded  upon  the  brain,  great  interest  has  been  attached 
to  the  exact  appreciation  of  its  dimensions,  and  hence  the  different  measurements  which 
have  been  adopted  for  this  purpose.  The  oldest  is  the  one  proposed  by  Camper,  under 
the  name  of  the  facial  angle.  This  angle  is  intended  to  measure  the  relative  proportions 
of  the  cranium  and  face.  It  is  taken  by  drawing  one  line  from  the  middle  incisors  of 
the  upper  jaw  along  the  front  of  the  forehead,  and  another  from  the  same  point  to  the 
auditory  meatus.  The  angle  included  between  these  lines  is  in  the  European  from  80" 
-0  SS*,  in  the  Mongolian  race  75°,  and  in  the  negro,  70°.  This  anatomical  fact  had  not 
escaped  the  attention  of  the  ancients.    We  observe  that  in  the  statues  of  their  heroes 

*  [An  old  Paris  inch  is  =1.065765  inch  English  ] 


40'-  OSTEOLOGY. 

and  gods  they  have  even  exaggerated  the  facial  angle,  which  is  generally  90°,  and  even 
more  in  the  case  of  Jupiter  Tonans. 

The  facial  angle  gives  no  information  respecting  the  capacity  of  the  posterior  regions 
of  the  cranium,  and,  consequently,  Daubenton  had  this  specially  in  view  in  his  mode  of 
measurement,  which  bears  the  name  of  the  occipital  angle  of  Daubenton.  This,  however, 
like  the  preceding,  and,  in  fact,  all  linear  measurements  applied  to  the  determination  of 
the  capacity  of  the  scull,  is  necessarily  inexact.  The  variable  thickness  of  the  walls  of 
the  cavity,  the  greater  or  less  development  of  the  sinuses,  and  the  projection  of  the  al- 
veoh,  or  their  obliteration  after  loss  of  the  teeth,  are  all  important  elements  in  the  esti- 
mate, which  have  been  entirely  neglected ;  and,  moreover,  the  facial  and  the  occipital 
angle  can  only  express  the  dimensions  in  one  direction.  The  capacity  of  a  cavity,  hke 
the  volume  of  a  solid,  can  only  be  determined  by  an  estimate  of  its  three  dimensions. 
Hence,  measures  of  surface,  and  measurements  taken  in  the  interior  of  the  cranium, 
must  be  employed  for  this  purpose.  Tliis  is  the  object  proposed  by  Cuvier,  in  comparing 
the  area  of  the  cranium  and  the  area  of  the  face,  cut  vertically  from  before  backward. 

A  section  of  the  cranium  represents  an  oval,  with  the  broad  end  backward  :  a  section 
of  the  face  is  triangular.  In  the  European,  the  area  of  the  cranium  equals  four  times 
that  of  the  face,  without  the  lower  jaw  ;  in  the  negro,  the  area  of  the  face  is  increased 
one  fifth.  The  most  general  result  which  can  be  deduced  from  a  comparison  of  the  cra- 
nimn  and  face  in  man  and  in  mammaUa,  is  that  they  are  developed  in  an  inverse  ratio. 
One  appears  to  augment  at  the  expense  of  the  other. 

Division  of  the  Cranium,  and  Description  of  its  different  Regions. 
The  cranium,  considered  as  one  piece,  presents  an  external  surface,  and  an  internal,  or 
encephalic  surface.  Many  of  the  objects  seen  on  these  surfaces  have  been  already  de- 
scribed with  the  particular  bones  to  which  they  belong ;  these  we  shall  merely  point 
out :  others,  which  result  from  the  union  of  the  bones  in  one  conunon  whole,  will  be  ex- 
amined more  in  detail. 

External  Surface  of  the  Cranium. 
The  external  surface  of  the  cranium  offers  for  consideration  a  superior  region  or 
vault,  an  inferior,  and  two  lateral  regions. 

The  superior  region  or  vault  is  bounded  by  a  circular  line,  passing  from  the  middle, 
frontal,  or  nasal  protuberance  {glabella),  along  the  temporal  fossa,  to  the  external  occipi- 
tal protuberance.  It  is  principally  covered  by  the  occipito-frontalis  muscle,  and  presents 
in  the  median  line,  1,  the  trace  of  the  union  of  the  two  primitive  halves  of  the  frontal 
bone  ;  2,  the  bi-parietal  or  sagittal  suture  (sagitta,  an  arroic),  which  forms  a  right  angle, 
in  front,  with  the  fronto-parietal  or  coronal  suture,  and  terminates  behind  at  the  superior 
angle  of  the  occipito-parietal  or  lambdoidal  suture  (from  the  Greek  letter  lambda). 

On  each  side  we  observe  three  eminences,  more  or  less  prominent  in  different  indi- 
viduals, and  always  most  marked  in  the  young.  These  are  the  frontal,  the  parietal,  and 
the  superior  occipital  protuberances.  Between  the  frontal  and  parietal  protuberances, 
the  coronal  suture  is  situated ;  and  between  the  parietal  and  the  occipital,  we  find  the 
lambdoid  suture.  Besides  these,  there  are  a  great  number  of  smaller  projections,  which 
Gall  has  also  denominated  protuberances,  and  to  which  much  importance  is  attached  in 
his  system. 

The  inferior  region  or  base  of  the  cranium  {fig.  21)  is  flattened  and  very  irregular.    It  is 
p-    21  bounded,  behind,  by  the  external  occipital  protuberance 

(a)  and  superior  semicircular  line  {a  b) ;  in  front,  by 
the  glabella,  or  nasal  eminence ;  laterally,  by  a  line 
passing  over  the  mastoid  and  external  orbital  process- 
es. I  shall  content  myself  by  describing  in  this  place 
the  posterior  half  of  the  base  of  the  cranium ;  the 
other  half  wiU  be  included  in  the  description  of  the 
face,  with  the  bones  of  which  it  concurs  in  forming 
the  orbital,  nasal,  and  zygomatic  fossaj.  The  ptery- 
goid processes  below,  and  the  posterior  edge  of  the 
sphenoid  above,  define  the  limits  of  these  two  portions. 
The  posterior  half  of  the  base  of  the  cranium  pre- 
sents, in  the  median  line,  and  in  an  order  from  behind 
forward,  the  external  occipital  protuberance  {a),  the 
external  occipital  crest  {a  c),  the  foramen  magnum 
(d),  and  condyles  (c),  the  basilar  process  («)>  ^^^  the 
transverse  suture,  which  results  from  the  articulation 
of  the  body  of  the  sphenoid  with  the  truncated  inferior 
angle  of  the  occipital  bone,  the  spheno-occipital  suture. 
On  each  side  we  observe  the  inferior  occipital  pro- 
tuberances, presenting  certain  variations  in  size  in 
different  subjects,  to  which  Gall  has  attached  great 
importance  in  his  craniological  system.     These  pro 


THE  CRANIUM  IN  GENERAL.  47 

tuberances  are  bounded  above  by  the  superior  semicircular  line  of  the  occipital  bone  (J); 
they  are  crossed  in  the  middle  by  the  inferior  semicircular  Une  {g),  which  is  separated 
from  the  preceding  by  muscular  impressions.  Between  the  inferior  semicircular  line 
and  the  occipital  foramen  are  also  a  number  of  inequalities  for  the  attachment  of  mus- 
cular fibres.  Still  more  anteriorly  is  the  posterior  condyloid  fossa,  and  occasionally  the 
posterior  condyloid  foramen  {g).  Outside  the  condyles  are  the  jugular  surface  (t),  the 
eminence  of  the  same  name,  and  the  petro-occipital  suture,  running  obliquely  from  behind 
forward  and  inward  (i  k),  without  any  indentations,  or  even  complete  juxtaposition  of 
the  bones,  and  terminating  behind  in  a  large  irregular  opening  (before  i),  the  foramen 
lacerum  postcrius,  which  is  divided  into  two  parts  by  a  tongue  of  bone  :  the  anterior  is 
the  smaller,  and  transmits  the  eighth  pair  of  nerves  ;  the  posterior  is  larger,  and  is  call- 
ed the  jugular  fossa,  from  its  receiving  the  enlarged  commencement  {sinus  or  diverticu- 
lum) of  the  jugular  vein.  The  petro-occipital  suture  terminates  in  front  in  another  irreg- 
ularly triangular  opening,  the  foramen  lacerum.  anterius  (k),  which  is  closed  by  cartilage, 
and  forms,  in  fact,  a  fontanelle  between  the  edges  of  the  occipital,  temporal,  and  sphe- 
noid bones.  In  front  of  the  petro-occipital  suture  is  the  inferior  surface  of  the  petrous 
bone,  with  its  numerous  asperities  ;  then,  still  proceeding  from  behind  forward,  we  find 
the  mastoid  process  (Z),  the  digastric  groove  (m),  the  stylo-mastoid  foramen  (7),  the  sty- 
loid and  vaginal  processes,  the  inferior  orifice  of  the  carotid  canal  (»),  and  the  petro-sphe- 
noidal  suture,  at  the  external  termination  of  which  the  osseous  portion  of  the  Eustachian 
tube  opens  by  an  orifice  directed  obliquely  for\vard  and  downward. 

Thus  all  the  sutures  of  the  posterior  half  of  the  base  of  the  cranium  meet  in  the  fora- 
men lacerum  anterius.  From  its  internal  angle,  the  spheno-occipital  suture  stretches 
across  to  the  same  part  of  the  opposite  foramen.  The  petro-sphenoidal  suture  sets  out 
from  the  external  angle,  and  becomes  continuous  with  the  fissure  of  Glasserius  ;  and 
the  petro-occipital  suture  extends  from  the  posterior  angle  to  the  occipito-mastoid  suture, 
which  it  joins  at  an  obtuse  angle  :  all  these  sutures  are  formed  by  juxtaposition,  and  not 
by  mutual  reception,  as  those  of  the  roof  of  the  scull. 

The  lateral  regions  of  the  cranium  are  bounded,  behind,  by  the  lambdoid  suture  ;  in  front, 
by  the  external  orbital  process  ;  and  above,  by  the  temporal  ridge.  This  region,  more  or 
less  rounded  in  different  subjects,  is,  nevertheless,  the  flattest  part  of  the  vault  of  the 
scull.  Proceeding  from  behind  forward,  we  observe,  1,  the  mastoid  region,  comprehend- 
ing the  mastoid  foramen  (9,  Jig.  21),  the  external  auditory  meatus,  the  glenoid  cavity, 
and  the  transverse  root  of  the  zygomatic  process  ;  2,  the  temporal  region  or  fos&a,  con- 
cave in  front,  convex  behind,  bounded  below  by  the  zygomatic  arch,  which  projects  con- 
siderably from  the  head,  more  especially  in  carnivorous  animals,  and  by  a  ridge  which 
separates  it  from  the  zygomatic  fossa.  The  temporal  fossa  is  traversed  by  numerous 
sutures,  arranged  in  the  following  manner  :  The  fronto-parietal  or  coronal  suture  (c  b.  Jig. 
22)  descends  vertically ;  from  its  inferior  extremity  two  others  proceed,  one  in  front,  the 
sphe no-frontal,  the  other  behind,  the  sphcno-parietal.  Each  of  these  soon  divides  into  two 
branches.  From  the  spheno-parietal  the  spheno-temporal  descends,  and  terminates  in 
the  fissure  of  Glasserius  ;  the  temporo-parietal  (b  i  d)  passes  horizontally,  and  becomes 
continuous  with  the  lambdoidal  suture  {df).  The  spheno-temporal  and  temporo-parie- 
tal sutures  are,  each,  part  of  the  squamous  suturk.  From  the  spheno-frontal  suture  the 
two  following  proceed  :  the  fronto-jugal,*  running  horizontally,  and  the  spheno-jugal, 
which  passes  downward ;  the  denominations  of  these  sutures  indicate  at  once  the  bones 
by  which  they  are  formed.  The  explanation  which  we  have  given  appears  the  most 
Ukely  to  facilitate  the  recollection  of  these  numerous  sutures,  by  connecting  them  with 
each  other.    The  following  table  exliibits  a  summary  of  all  that  has  been  stated : 

I^Spheno-frontaJ  {  gpheno-jugal. 

All  these  sutures  are  remarkable,  from  the  circumstance  that  the  bones  which  enter 
into  their  formation  are  cut  obliquely  like  scales,  and  for  the  most  part  the  edge  of  the 
bone  above  is  overlapped  by  the  edge  of  the  bone  below,  so  that  each  inferior  scale,  like 
the  abutment  of  an  arch,  prevents  the  superior  one  which  corresponds  to  it  from  being 
forced  outward.     (Vide  Mechanism  of  the  Cranium.     Sy\desmology.) 

Internal  Surface  of  the  Cranium. 

In  order  to  examine  the  internal  surface  of  the  cranium,  it  is  necessary  to  make  two 
sections,  one  horizontally  from  the  occipital  protuberance  to  the  glabella  {Jig.  23),  the 
other  vertically  along  the  median  line  from  before  backward  {Jig.  22). 

In  the  median  line,  proceeding  from  before  backward,  we  observe  the  frontal  crest  or  ridge, 
and  the  longitudinal  groove,  stretching  from  the  frontal  crest,  along  the  roof  of  the  scull  to 
the  internal  occipital  protuberance.  In  this  groove,  which  is  of  no  great  depth,  we  find  aline 
which  indicates  the  place  of  union  of  the  two  pieces  of  the  frontal  hone  during  the  earJy 

♦  Tho  malar  bone  is  often  called  the  jvigal  bone,  and  hence  the  names  of  fronto-jugal  and  spheno-jugaL 


OSTEOLOGY. 


Fig.  23. 


Fig.  22.  periods  of  life,  and  the  internal  surface  of  the 

sagittal  suture.  It  receives  the  superior  longi- 
tudinal sinus  in  its  entire  extent,  and  contains 
the  internal  orifices  of  the  parietal  foramina. 

On  each  side  are  the  frontal  fossae,  correspond- 
ing to  the  protuberances  of  the  same  name, 
and  the  internal  surface  of  the  fronto-parietal 
(coronal)  suture  {be, Jig.  22);  the  encephalic 
surface  of  the  parietal  bone  (^i  dfc),  and  the 
parietal  fossa;  the  lambdoid  suture  {df),  and 
the  superior  occipital  fossa.  We  may  remark 
that  the  fossce  are  deeper  than  would  "seem  to 
be  indicated  by  the  external  prominences,  be 
cause  they  are  partly  formed  at  the  expense  of 
the  bone  itself;  and  that  the  sutures  are  less 
deeply  denticulated  on  their  internal  than  on  their  external  aspect. 

Lastly,  the  whole  internal  surface  of  the  vault  of  the  cranium,  but  especially  that  of 
the  parietal  bones,  is  traversed  by  ramified  grooves  (i  i),  partly  for  veins,  partly  for  ar- 
teries ;  the  venous  grooves,  which  are  not  perceptible  in  all  subjects,  but  which  are  very 
large  in  some,  are  distinguished  from  the  arterial,  as  M.  Breschet  has  pointed  out,  by 
their  being  perforated  by  numerous  foramina. 

The  base  of  the  cranium  {fig.  23),  presents  three  series  of  fossae,  or  three  regions,  ar- 
ranged, as  it  were,  in  steps  upon  an  inclined  plane,  from  before  backward,  and  from  above 
downward.     They  are  described  as  the  anterior,  middle,  and  posterior  regions. 

Anteriw  or  cthmoido-frontal  region.  In  this  region  we  observe,  in  the  middle,  the  eth- 
moidal fossa,  in  which  is  the  foramen  caecum ;  tl^e 
crista  gaUi  (a) ;  the  ethmoidal  grooves,  and  the  for- 
amina with  which  they  are  perforated  ;  the  ethmoi 
dal  fissure,  for  the  ethmoidal  or  nasal  branch  of  the 
ophthalmic  nerve  ;  the  ethmoido-frontal  sutures,  run- 
ning from  before  backward  ;  the  orifices  of  the  inter- 
nal orbitary  foramina ;  and  the  trace  of  the  ethnw-sphe- 
noidal  suture,  running  transversely.  Behind  the  eth- 
moidal fossa,  the  surface  of  the  sphenoid  is  slightly 
impressed  by  the  passage  forward  of  the  olfactory 
nerves. 

Laterally,  we  see  the  orbital  plates  {b),  remarkable 
for  the  prominence  of  their  mammillary  projections, 
and  traversed  by  small  grooves  for  the  ramifications 
of  the  middle  meningeal  artery ;  and  the  fronto-sfhe- 
Twidal  sutures  (before  c),  which  mark  the  union  of  the 
lesser  wings  of  the  sphenoid  (c),  with  the  orbital  por- 
tion of  the  frontal  bone  {b).  The  orbital  plates  sup- 
port the  anterior  lobes  of  the  brain. 

The  middle  region  exhibits  in  the  centre  a  fossa,  in 
which  we  observe  the  depression  for  the  olfactory 
nerves,  the  optic  groove,  and  olivary  process  (before 
d) ;  the  pituitary  fossa  (d),  deeply  excavated  behind  ;  the  quadrilateral  plate  (behind  d) ; 
the  cavernous  grooves  ;  and  the  anterior  and  posterior  clinoid  processes.  On  the  sides 
we  find  very  deep  fossae,  which  correspond  with  the  middle  lobes  of  the  brain,  called 
middle  lateral  fossa  of  the  base  of  the  cranium;  they  are  broad  externally,  narrow  inter- 
nally, and  are  bounded  in  front  by  the  posterior  edge  of  the  lesser  wings  of  the  sphenoid  (c), 
and  behind  by  the  superior  border  of  the  petrous  portion  of  the  temporal  bone  (/«)•  They 
are  formed  by  the  superior  surface  of  the  petrous  portion,  the  internal  surface  of  the  squa- 
mous portion  of  the  temporal,  and  the  superior  surface  of  the  great  wings  of  the  sphe- 
noid. They  present,  successively  from  before  backward,  the  sphenoidal  fissure  (or  for- 
amen lacerum  orbitale) ;  the  foramen  rotundum,  or  superior  maxillary '(2) ;  the  foramen 
ovale  (3) ;  the  foramen  spinosum  (4) ;  the  internal  orifices  of  the  foramen  lacerum  an- 
terius  and  carotid  canal  (before  5),  and  the  hiatus  Fallopii.  We  see  here,  also,  the  union 
of  the  sphenoid  with  the  squamous  and  petrous  portions  of  the  temporal  bone,  forming 
the  sphcno-tcmporal  {i  and  c)  and  pctro-sphe?ioidal  sutures.  This  fossa  is  traversed  from  be- 
hind forward  and  outward  by  a  groove  {i  4),  which  commences  at  the  foramen  spinosum, 
passes  along  the  external  border  of  the  sphenoid,  or,  rather,  is  hollowed  out  from  the 
spheno-temporal  suture,  and  divides  into  two  branches ;  the  anterior,  the  larger,  pro- 
ceeds to  the  anterior  inferior  angle  of  the  parietal  bone,  with  the  anterior  ramified  groove 
m  which  it  becomes  continuous  ;  the  posterior  is  directed  horizontally  backward  to  the 
posterior  inferior  angle  of  the  parietal  bone.  In  some  cases,  the  portion  of  the  groove 
which  extends  from  the  foramen  spinosum  to  the  summit  of  the  lesser  wing  of  the  sphe- 
noid, almost  equals  in  diameter  the  lateral  grooves,  and  it  is  then  almost  always  pierced 
by  foramina :  it  contains  the  middle  meningeal  artery,  and  a  large  vein 


THE  CEANIUM  IN  GENERAL.  49 

Posterior  region  of  the  base  of  the  cranium.  This  region  presents  in  the  middle  the  ba- 
silar groove  (k) ;  the  spheno-occipital  suture,  the  foramen  magnum  (m),  the  anterior  con- 
dyloid foramina  (8)  {Ji,fig.  22),  the  internal  occipital  ridge,  and  protuberance  {o,fig.  21). 
Laterally,  the  inferior  oceipital  fossa,  the  deepest  in  the  scull,  which  are  formed  by  the 
posterior  surface  of  the  petrous  portion  of  the  temporal  bone,  almost  the  whole  of  the  en- 
cephalic surface  of  the  occipital  bone,  and  the  posterior  inferior  angle  of  the  parietal. 
We  find  here  the  foramen  lacerum  posterius  (7),  the  suture  which  unites  the  temporal  to 
the  occipital  bone,  and  along  the  petro-occipital  suture,  a  smedl  groove  named  inferior  pe- 
trosal (on  each  side  of  A:), 

The  inferior  occipital  fossa  is  bounded  above  by  a  broad  and  deep  groove  (n),  intend- 
ed to  lodge  the  lateral  sinus,  and  called  the  lateral  groove.  It  commences  at  the  internal 
occipital  protuberance  (o),  and  proceeds  horizontedly  outward  to  the  base  of  the  petrous 
portion,  where  it  is  again  enlarged,  and  passes  roimd,  extending  downward  and  inward 
along  the  occipital  fossa,  until  it  arrives  at  the  occipito-meistoid  suture  (r),  where  it  rises 
and  terminates  in  the  foramen  lacerum  posterius.  The  inferior  occipital  fossa  is  divi- 
ded into  two  parts  by  this  groove  :  an  anterior,  formed  by  the  posterior  face  of  the  pars 
petrosa,  and  a  posterior,  formed  by  the  occipital  bone.  In  this  groove,  the  mastoid  fora- 
men, the  posterior  condyloid  foramen,  when  it  exists,  and  the  superior  and  inferior  petrosal 
grooves  open. 

The  dimensions  of  the  lateral  grooves  are  extremely  variable ;  inost  commonly  the 
left  is  smaller  and  shallower  than  the  right,  especially  in  its  horizontal  portion. 

Of  the  eminences  and  depressions  on  the  internal  surface  of  the  cranium,  the  most 
deeply  marked  are  those  situated  upon  the  base.  This  is  more  especially  the  case  with 
regard  to  the  orbital  plates  and  the  middle  and  lateral  fossae.  Since  the  publication  of 
the  works  of  Gall  and  Spurzheim,  anatomists  have  re-adopted  the  opinion  of  the  an- 
cients, who  regarded  these  eminences  and  depressions  as  corresponding  respectively 
with  the  anfractuosities  and  the  convolutions  of  the  brain :  the  cranium,  in  fact,  is  mould- 
ed upon  the  brain ;  to  be  convinced  of  which,  it  is  only  necessary  to  repeat  the  following 
experiment,  which  I  have  often  made  for  this  purpose.  Remove  the  brain  from  the 
cavity  of  the  cranium,  and  supply  its  place  by  plaster  of  Paris  ;  when  dry,  this  substance 
will  present  a  faithful  model  of  the  convolutions  and  anfractuosities  of  the  brain.  In 
cases  of  chronic  hydrocephalus,  where  the  inequalities  of  the  brain  are  effaced  by  the 
accumulation  of  fluid,  the  internal  surface  of  the  cranium  shows  scarcely  any  vestiges 
of  eminences  and  depressions.  The  osseous  tissue,  notwithstanding  its  hardness,  is 
easily  moidded  around  organs,  and  yields  with  facility  to  the  compression  which  soft 
parts  exercise  upon  it.  It  is  very  uncommon  to  open  the  cranium  of  a  subject,  some- 
what advanced  in  years,  without  observing  in  some  points  a  more  or  less  considerable 
absorption  of  the  parietes  of  the  scull,  occasioned  either  by  clusters  of  certain  smaU 
white  bodies,  called  glandulae  Pacchioni,  or  by  dilated  veins. 

One  anatomical  fact  worthy  of  notice  is  the  want  of  any  configuration  of  the  external 
surface  conformable  in  its  details  with  that  of  the  internal  surface :  compare,  for  in- 
stance, the  roof  of  the  orbit  with  the  cranial  surface  of  the  orbital  plate  of  the  frontal 
bone.  This  difference  is  due  to  the  circumstance  that  the  digital  impressions  encroach 
on  the  diploe,  and  are,  in  part,  excavated  from  the  space  otherwise  occupied  by  it.  The 
two  compact  laminag  which  form  the  bones  of  the  cranium  are  in  some  measure  inde- 
pendent of  each  other ;  the  internal  one  belongs,  so  to  speak,  to  the  brain ;  the  exter- 
nal to  the  locomotive  system.  The  diploe  is  the  limit  of  these  two  laminae.  This  ana- 
tomical fact  is  at  variance  with  the  doctrine  of  Gall  respecting  the  protuberances ;  it  proves 
that  the  cerebral  convolutions  are  not  faithfully  represented  by  external  prominences. 

In  order  to  complete  the  anatomical  history  of  the  cranium,  it  yet  remains  to  consider, 
1.  Its  general  development;  2.  The  connexion  of  its  several  parts.  (For  this  latter 
subject,  see  Syndesmology.) 

As  to  the  analogies  which  have  been  so  ingeniously  established  between  the  cranium 
and  the  vertebral  column,  a  detailed  analysis  of  them  would  be  out  of  place  in  an  ele- 
mentarv  work  like  the  present. 

Development  of  the  Cranium. 

The  cranium  is  remarkable  for  the  early  period  at  which  its  development  commences. 
As  soon  as  ihe  embryo  is  sufficiently  advanced  in  growth  to  exhibit  any  distinction  oi 
parts,  the  head,  under  the  form  of  an  ovoid  vesicle,  greatly  exceeds  the  magnitude  of 
the  whole  body  With  regard  to  the  order  in  which  the  different  parts  are  ossified,  we 
may  remark,  that  the  bones  of  the  roof  precede  those  of  the  base,  in  like  manner  as  in 
the  vertebrae  the  laminae  are  ossified  before  the  bodies.  In  both  cases  the  evolution  is 
most  prompt  in  those  parts  which  are  especially  destined  to  protect  import£uit  organs. 

Cranial  Bones  at  Birth. 
The  bones  of  the  roof  of  the  scull  appear  before  those  of  the  base,  but  at  birth  ossifi- 
cation is  less  advanced  in  the  roof  than  in  the  base  ;  accordingly,  in  a  foetus  at  the  full 
time,  the  bones  of  the  base  form  a  solid  whole,  and  are  immovable,  while  those  of  the 

G 


W  OSTEOLGOY. 

roof  are  separated  by  membranous  intervals,  which  permit  of  pretty  extensive  move- 
ments, so  that  at  this  period  the  roof  of  the  cranium  yields,  in  a  great  degree,  to  pressure. 
At  birth,  there  is  nothing  resembling  the  mode  of  union  called  suture.  Nevertheless, 
each  bone  presents  denticulations  like  the  teeth  of  a  comb  round  the  circumference. 
The  existence  of  these  indentations  before  the  period  when  the  bones  come  into  con- 
tact, proves  that  they  are  not  the  result  of  any  mechanical  action  produced  by  their 
meeting;  the  only  influence  of  this  kind  to  which  they  are  subjected  during  their  forma 
tion,  is  the  deviation  of  opposing  denticulations.  The  frontal  suture  is  the  first  developed. 
Another  peculiarity  of  this  stage  of  development  is  the  existence  of  those  membra- 
nous intervals  denominated  fontanelles.  They  are  produced  in  the  following  manner : 
the  process  of  ossification  commences  in  the  centre  of  the  bone,  and  advances  from  that 
point  to  the  circumference,  the  most  distant  parts  of  the  bone  being,  of  course,  the  last 
to  be  ossified.  These  points,  in  broad  or  flat  bones,  are  the  angles,  and,  consequently, 
at  the  place  where  several  angles  of  diflferent  bones  ultimately  unite,  there  must  exist 
an  unossified  space  at  this  time  :  these  spaces  are  the  fontanelles.  They  have  all  been 
pointed  out  in  the  description  of  the  cranial  bones  ;  they  are  of  especial  importance  to 
the  accoucheur,  on  account  of  the  indications  which  they  furnish  for  determining  the 
position  of  the  child.  All  traces  of  the  fontanelles  are  completely  obliterated  at  the  age 
of  four  years. 

The  Wormian  Bones. 

The  Wormian  bones  should  be  regarded  as  supplementary  points  or  centres,  developed 
when  the  general  ossification  proceeds  somewhat  slowly ;  and  we  therefore  consider  it 
proper  to  include  a  description  of  them  in  the  account  of  the  development  of  the  cranium. 

The  Wormian  bones,  so  called  because  the  first  description  of  them  has  been  assigned 
to  Wormius,  a  physician  in  Copenhagen,  are  also  denominated  exacted  bones,  ossa  trique- 
tra,  or  complimentary  bones  of  the  scull.  They  are  extremely  variable,  both  in  situation, 
number,  and  size  ;  but  they  are  most  common  in  the  lambdoid  suture,  i.  e.,  in  the  most 
rugged  of  all  the  sutures,  the  asperities  of  which  they  tend  to  increase.  This  fact 
should  not  be  overlooked  in  examining  fractures  of  the  cranium.  The  most  remarkable 
of  all  the  Wormian  bones  is  the  one  which  sometimes  supplies  the  place  of  the  superior 
angle  of  the  occipital,  and  which  Blasius  has  called  the  triangular  bone  ;  it  is  the  epactal 
bone  properly  so  called.  It  is  not  uncommon  to  find  a  Wormian  bone  in  the  sagittal  su- 
ture, and  this  may  be  compared  to  the  inter-parietal  bone  of  some  animals.  Bertin  has 
described  a  quadrangular  bone  occupying  the  situation  of  the  anterior  fontanelle,  and 
resembling  it  in  figure  :  I  have  myself  met  with  such  a  fonnation.  The  anterior  inferior 
angle  of  the  parietal  is  sometimes  formed  by  a  Wormian  bone ;  I  have  seen  one  in  the 
squamous  suture. 

In  some  sculls  the  whole  of  the  occipital  bone  above  the  occipital  protuberance  is 
formed  by  these  bones.  Generally  both  tables  of  the  bone  enter  into  the  formation  of 
the  Wormian  bones  ;  but  there  are  instances  in  which  they  are  confined  to  the  external, 
and  others  to  the  internal  table. 

The  Wormian  bones  are  not  always  visible  in  the  interior  of  the  cranium :  in  some 
cases  they  are,  as  it  were,  incrusted  in  the  substance  of  the  bone,  at  the  circumference 
of  which  they  are  observed. 

Their  mode  of  development  resembles  that  of  the  broad  bones,  i.  c.,  it  proceeds  by  ra- 
diation from  the  centre  to  the  circumference.  According  to  Beclard,  they  are  not  devel- 
oped until  five  or  six  months  after  birth  :  at  their  junction  with  the  surrounding  bones 
they  form  sutures,  which  are  the  first  to  become  effaced  in  after  life. 

From  all  that  has  been  said  regarding  this  class  of  bones  (which  are  in  a  manner  acci- 
dental, for  they  are  neither  constant  in  number  nor  in  their  existence),  it  is  evident  that 
they  can  be  only  considered  as  supplementary  points  of  ossification,  and  not  as  performing 
an  important  office  in  contributing  to  the  solidity  of  the  cranium,  as  the  name  cles  de 
voiUe,  given  to  them  by  some  anatomists,  would  seem  to  indicate. 

Progress  of  Development  in  the  Adult  and  the  Aged. 

The  cartilaginous  lamina  which  separates  the  bones  at  first,  gradually  becomes  ossi- 
fied. The  sutures  become  so  serrated  that  it  is  almost  impossible  to  separate  the  bones 
without  breaking  some  of  their  teeth.  At  the  same  time  that  the  bones  increase  in 
breadth,  they  augment  in  thickness ;  the  diploe,  which  at  first  did  not  exist,  is  developed 
between  the  two  plates.  In  the  adult,  several  bones  already  begin  to  join  by  osseous 
union ;  of  this  we  have  an  example  in  the  sphenoid  and  occipital,  which  at  an  early  pe- 
riod form  one  bone. 

In  the  aged,  the  traces  of  the  sutures  are  in  a  great  measure  effaced,  so  that  in  cer- 
tain cases  the  whole  scull  would  seem  to  be  composed  of  one  entire  piece.  The  con- 
tinuity of  some  bones  is  occasionally  such,  that  the  venous  canals  of  the  one  communi- 
cate and  open  directly  into  those  of  the  other.  It  is  not  uncommon  to  find  the  bones  of 
an  old  subject  thin  and  translucent  like  horn,  in  a  greater  or  less  extent.  This  diminu- 
tion of  thickness,  added  to  the  increasing  fragility  of  the  osseous  tissue,  affords  an  ex- 


SUPERIOR  MAXILLARY    BONES.  51 

planation  of  the  ease  with  which  the  sculls  of  old  people  may  be  broken :  and  the  con- 
tinuity of  the  bones  explains  the  possibility  of  the  fracture  being  much  extended. 

The  greatest  variety  exists  as  to  the  thickness  and  density  of  the  bones  of  the  scull  in 
old  age,  Generally  they  are  as  brittle  as  glass,  but  in  some  instances  they  are  so  soft 
and  spongy  that,  although  easily  depressed,  they  can  scarcely  be  fractured  by  the  blow 
of  a  hammer.  I  have  frequently,  in  old  people,  seen  the  teeth  of  the  parietal  and  lamb- 
doidal  sutures  soft,  placed  in  juxtaposition,  and  merely  joined  by  a  soft  fibrous  sub- 
stance, which  admitted  of  their  being  separated  without  difficulty.  The  lambdoidal  su- 
ture is  the  one  which  the  most  frequently  presents  this  disposition,  and  in  all  the  in- 
stances of  this  kind  which  I  have  met  with,  the  superior  borders  of  the  occipital  overlap 
the  corresponding  borders  of  the  parietal. 

The  F^ce. 

The  face  is  tnat  very  complicated  osseous  structure,  which  is  situated  at  the  anterior 
and  inferior  part  of  the  head,  and  is  hollowed  out  into  deep  cavities  for  the  reception  of 
the  organs  of  sight,  smell,  and  taste,  and  for  the  apparatus  of  mastication. 

The  face  is  divided  into  two  portions,  the  upper  and  the  lower  jaw.  The  lower  jaw  is 
formed  by  one  bone  only ;  the  upper  jaw  consists  of  thirteen  bones.  But,  although  this 
circumstance  tends  to  establish  a  great  difference  between  the  two,  yet  it  must  be  re- 
marked, that  all  the  parts  of  the  upper  jaw  are  so  immovably  united,  that  in  appearance 
they  form  only  one  bone  ;  and,  moreover,  that  it  is  essentially  formed  by  one  fundamental 
piece,  the  superior  maxillary  bone,  to  which  all  the  others  are  attached  as  accessory  parts. 

Of  the  fourteen  bones  which  constitute  the  face,  two  only  are  median  or  single  :  viz., 
the  vomer,  and  the  inferior  maxilla.  All  the  others  are  double,  and  form  six  pairs,  viz., 
the  superior  maxillary,  the  malar,  palate,  and  proper  nasal  bones,  the  ossa  unguis,  and 
the  inferior  turbinated  bones. 

The  Superior  Maxillary  Bones  {figs.  24  and  25,  with  the  Palate  Bones). 

They  are  two  in  number,  united,  to  a  certain  extent,  in  the  median  line,  and  form  al- 
most the  whole  of  the  upper  jaw.  Their  figure  is  very  irregular :  they  belong  to  the 
class  of  short  bones.  They  have  three  surfaces,  an  external,  an  internal,  and  a  superi- 
or ;  and  three  borders,  an  anterior,  a  posterior,  and  an  inferior. 

External  or  Facial  Surface  {fig.  24). — Proceeding  from  before  backward,  we  observe  a 
small  fossa  in  which  the  myrtiform  muscle  {depressor  labii  supe- 
rioris  et  alee  nasi)  is  inserted,  and  which  is  bounded  externally 
by  the  ridge  which  forms  the  alveolus  of  the  canine  tooth ;  a 
deeper  fossa,  named  fossa  canina,  or  infra  orhitalis,  surmounted 
by  the  orifice  of  the  infra  orbitary  canal  (o) ;  and,  more  posteri- 
orly, a  vertical  ridge,  which  separates  the  fossa  canina  from  the 
maxillary  tuberosity  (m).  This  protuberance,  which  is  most 
prominent  before  the  appearance  of  the  wisdom  tooth,  is  trav- 
ersed by  small  canals,  the  posterior  and  superior  dental,  which 
transmit  vessels  and  nerves  of  the  same  name.  From  the  an- 
terior part  of  this  region,  a  long  vertical  process  arises,  the  as- 
cending or  nasal  process  {a  b)  of  the  superior  maxilla.  It  is  of  a  pyramidal  shape,  and  flat- 
tened. Its  external  surface  is  smooth,  and  presents  the  openings  of  certain  vascular  ca- 
nals which  communicate  with  the  interior  of  the  nasal  fossae,  and  some  inequalities  for 
the  insertion  of  the  common  elevator  of  the  upper  lip  and  ala  of  the  nose.  On  the  inter- 
nal surface  {fig.  25)  we  observe,  in  succession  from  above  downward,  a  rough  surface, 
which  assists  in  closing  the  anterior  cells  of  the  ethmoid  ;  a  horizontal  ridge,  to  which 
the  middle  turbinated  bone  is  attached  ;  a  concave  surface,  which  forms  part  of  the  mid- 
dle meatus  of  the  nose  ;  and  another  horizontal  ridge  for  articulation  with  the  inferior 
turbinated  bone  :  like  the  external,  this  surface  also  is  perforated  by  foramina,  and  mark- 
ed by  arterial  furrows.  Its  anteriw  edge  {a  b,figs.  24,  25)  thin,  and  bevelled  internally,  i& 
applied  to  the  nasal  bone.  The  posterior  edge  is  thick,  and  marked  by  the  lachrymo-nasal 
g'oove,  which  forms  part  of  the  lachrymal  groove  above,  and  of  the  nasal  duct  below.  It 
has  two  edges  or  lips  :  the  internal,  which  is  very  thin,  articulates  with  the  os  unguis 
and  the  inferior  turbinated  bone  ;  the  external,  which  is  rounded,  gives  attachment  to 
the  straight  tendon  and  some  fibres  of  the  orbicularis  palpebrarum  muscle.  The  direc- 
tion of  the  lachrymo-nasal  groove  is  slightly  curved  ;  the  convexity  being  internal  and 
in  front,  the  concavity  external  and  behind.  The  summit  of  the  nasal  process  is  trun- 
cated and  serrated  for  articulation  with  the  nasal  notch  of  the  frontal  bone. 

Superior  or  Orbital  Surface  {c,fig.  24). — This  is  the  smallest  of  the  three  surfaces.  It 
forms  almost  the  entire  floor  of  the  orbit :  it  is  triangular,  and  slightly  oblique  from  within 
outward,  and  from  above  downward,  and  presents  a  groove  behind,  which  is  continuous 
with  the  infra-orbitary  canal.  This  last-named  passage,  at  first  a  mere  channel,  after- 
ward a  complete  canal,  passes  from  behind  forward  and  inward,  bends  down  and  opens 
at  the  upper  part  of  the  canine  fossa.  Before  its  termination,  it  gives  off  a  small  canal, 
the  anterior  and  superior  dental,  which  runs  in  the  anterior  wall  of  the  maxiUary  sinus, 


53  OSTEOLOGY. 

and  transmits  the  vessels  and  nerves  which  are  distributed  to  the  incisor  and  canine 
teeth.  Sometimes  this  branch  of  the  canal  opens  into  the  maxillary  sinus.  In  many 
subjects  I  have  seen  it  curve  backward,  and  conduct  a  communicating  branch  between 
the  infra-orbitary  and  palatine  nerves  as  far  as  the  maxillary  tuberosity.  The  orbiial 
surface  is  bounded  by  an  external  edge,  which  forms  part  of  the  spheno-maxillary  fissure  ; 
by  an  internal  edge,  which  articulates  with  the  os  unguis,  the  os  planum  of  the  ethmoid,  and 
the  palate  bone  ;  and  by  an  anterior  edge,  which  forms  part  of  the  rim  of  the  orbit.  At 
the  external  termination  of  this  edge  is  a  very  irregular  eminence,  appearing  as  if  part  of 
the  bone  had  been  broken  off:  this  is  the  malar  process,  which  corresponds  with  the  sum- 
mit of  the  maxillary  sinus,  and  is  articulated  with  the  malar  bone.  At  the  internal  ex- 
tremity of  the  orbital  edge,  we  find  the  ascending  process  already  described. 

Internal  or  Naso-palatine  Surface  {Jig.  25). — This  surface  is  divided  into  two  unequal 
parts  by  a  horizontal  square  plate,  which  intersects  it  at  right 
angles.  This  plate  is  the  palatine  process  {t),  the  superior  surface 
of  which,  smooth  and  hollow,  is  broader  posteriorly  than  anteri- 
orly, and  forms  part  of  the  floor  of  the  nasal  fossae  :  its  inferior 
surface  is  rough,  and  forms  part  of  the  roof  of  the  palate  :  its 
internal  border  (t)  is  very  thick  in  front,  and  articulates  with 
the  corresponding  edge  of  the  opposite  bone.  This  border  is 
surmounted  by  a  crest,  which  contributes  to  form  the  furrow 
into  which  the  vomer  is  received,  and  which  presents,  at  the 
junction  of  its  anterior  with  the  two  posterior  thirds,  a  groove 
(r)  running  obliquely  upward  and  backward.  This  groove,  when 
united  with  a  similar  one  on  the  opposite  bone,  forms  the  anterior  palatine  or  incisive  ca- 
nal, which  is  single  below  and  double  above.  The  anterior  edge  of  the  palatine  process 
is  very  narrow,  and  forms  part  of  the  anterior  opening  of  the  nasal  fossae  :  the  posterior 
edge,  bevelled  at  the  expense  of  the  superior  table,  supports  the  horizontal  portion  of  the 
palate  bone. 

That  part  (to)  of  the  internal  surface  of  the  maxillary  bone  which  is  situated  below 
the  palatine  process,  is  of  no  great  extent :  it  forms  part  of  the  arch  of  the  palate.  A 
furrow  more  or  less  deep,  and  bounded  by  projecting  edges,  runs  along  the  external  bor- 
der of  the  palatine  process,  and  protects  the  posterior  palatine  vessels  and  nerves.  The 
raucous  membrane  of  the  palate  covers  this  region  of  the  bone.  The  part  of  the  inter- 
nal surface  (n)  of  the  superior  maxillary  bone  which  is  above  the  palatine  process,  be- 
longs to  the  nasal  fossa :  it  is  covered  by  the  pituitary  membrane.  We  observe  here 
from  before  backward,  1,  the  internal  surface  (c)  of  the  ascending  process  (a) ;  2,  below 
the  inferior  ridge,  a  smooth  surface  which  forms  part  of  the  inferior  meatus  of  the  nose  ; 
3,  the  inferior  orifice  (behind  c)  of  the  lachrymo-nasal  groove,  sometimes  converted  into 
a  complete  canal  by  a  bridge  of  bone  ;  4,  the  opening  of  the  maxillary  sinus  (s),  which 
appears  wide  in  a  detached  bone,  but  in  its  natural  connexion  is  contracted  by  prolonga- 
tions of  the  palate  bone,  the  ethmoid,  the  inferior  turbinated  bone,  and  the  os  unguis,  all 
of  which  are  articulated  with  the  circumference  of  this  opening  ;  it  is  still  farther  dimin- 
ished when  the  bones  are  covered  by  their  pituitary  membrane.  At  its  lower  part,  this 
orifice  presents  a  fissure  in  which  a  lamina  belonging  to  the  palate  bone  is  received  :  this 
method  of  articulation  has  received  the  name  of  Schindylesis.  At  the  upper  part  are 
small  cells,  which  unite  with  the  ethmoid  ;  behind  the  orifice  is  a  rough  surface,  which 
articulates  with  the  palate  bone  ;  and,  lastly,  a  groove,  which  forms  part  of  the  posterior 
palatine  canal. 

The  orifice  which  we  have  just  described  leads  into  the  interior  of  a  cavity  denom- 
inated maxillary  sinus,  or  antrum  of  Highmore,  although  it  had  been  before  very  accurate- 
ly described  by  Vesalius.  It  is  hollowed  out  from  the  substance  of  the  maxillary  bone, 
and  has  the  form  of  a  pyramid,  the  base  of  which  corresponds  with  the  internal  surface 
of  the  bone  ;  the  summit  with  the  malar  process  ;  the  superior  wall  with  the  floor  of  the 
ojbit ;  the  anterior  wall  with  the  fossa  carina,  and  the  posterior  with  the  maxillary  tuber- 
osity. These  two  last-mentioned  walls  are  traversed  by  linear  projections  or  ridges, 
which  correspond  with  the  anterior  and  posterior  dental  canals.  There  is  also  one  ridge 
upon  the  superior  wall :  it  indicates  the  passage  of  the  infra-orbitary  canal.  The  ex- 
treme tenuity  of  this  superior  or  orbitary  wall  is  an  anatomical  fact  of  great  importance, 
because  it  explains  the  influence  which  tumours  developed  in  the  sinus  exert  upon  the 
organs  contained  in  the  cavity  of  the  orbit.  The  septum  between  the  sinus  and  the  bot- 
tom of  the  alveoli  is  also  so  thin,  that  an  instrument  can  easily  penetrate  into  the  sinus 
in  this  situation.     This  remark  applies  particularly  to  the  alveolus  of  the  canine  tooth. 

The  anterior  harder  {g  a,  figs.  24  and  25)  of  the  superior  maxilla  presents,  below,  a  ver- 
tical portion  (g-  d),  surmounted  by  a  small  eminence  called  the  nasal  spine  (a) :  it  is  then 
hollowed  out  into  a  deep  notch  (a  h),  to  form  half  the  anterior  orifice  of  the  nasal  fossae ; 
and,  lastly,  becomes  continuous  with  the  anterior  edge  (h  a)  of  the  ascending  process. 
The  posterior  harder  is  vertical  and  very  thick  :  it  articulates  below  with  the  pterygoid 
process,  through  the  medium  of  the  palate-bone  :  above,  it  forms  part  of  the  pteiygo- 
maxillary  fissure.  • 


PALATE   BONES.  53 

The  inferior  or  alveolar  border  {g  k)  is  the  thickest  and  strongest  part,  being,  in  some 
respects,  the  base  of  the  bone.  It  is  hollowed  into  conical  cavities  separated  by  thin 
septa.  These  cavities  are  the  alveoli  or  sockets  of  the  teeth  :  they  are  proportioned  in 
dimensions  to  the  size  of  the  fangs  vi^hich  they  are  intended  to  lodge,  and  in  like  man- 
ner are  subdivided  into  two,  three,  or  four  secondary  cavities.  The  bottom  of  these  al- 
veoU  is  in  apposition  with  the  maxillary  sinus,  into  which  they  occasionally  open.  This 
border  presents,  especiaUy  in  front,  flutings  or  projections  which  correspond  with  the 
alveoli,  and  depressions  which  mark  the  inter-alveolar  septa. 

In  young  subjects  we  may  observe,  chiefly  behind  the  incisor  teeth,  some  very  remark- 
able foramina,  to  which  much  importance  has  been  attached  as  connected  with  the  phe- 
nomena of  dentition. 

Internal  Structure. — This  bone  is  remarkably  light  for  its  size,  on  account  of  the  larg« 
cavity  which  it  encloses.  It  is  more  compact  than  most  of  the  short  bones,  and  has  spongy 
tissue  only  in  the  alveolar  border,  the  maxillary  tuberosity,  and  the  malar  eminence. 

Connexions. — The  superior  maxilla  is  articulated  with  two  bones  of  the  cranium,  the 
frontal  and  the  ethmoid,  and  with  all  the  bones  of  the  face.  It  lodges  eight  of  the  teeth 
of  the  upper  jaw. 

Development. — Anatomists  are  not  at  all  agreed  respecting  the  number  and  arrange- 
ment of  the  osseous  points  which  concur  in  forming  the  superior  maxilla. 

In  the  maxillary  bone  of  the  fcetus,  and  sometimes  even  in  that  of  the  adult,  there  are, 
as  I  can  attest  from  observation,  two  very  remarkable  fissures,  which  would  seem  to  in- 
dicate the  primitive  separation  of  the  bone  into  three  pieces. 

1.  The  first  fissure,  which  may  be  called  the  incisive  fissure,  is  visible  on  each  side  of 
the  arch  of  the  palate.  It  commences  at  the  septum,  which  divides  the  alveoli  of  the 
canine  tooth  and  lateral  incisor,  is  continued  backward  to  the  anterior  palatine  canal, 
and  is  prolonged  above  on  the  internal  surface  of  the  ascending  process.  This  fissure 
is  apparent  only  on  the  internal  surface  of  the  superior  maxilla  :  it  either  does  not  exist 
at  all  upon  the  external  surface,  or  is  so  early  obliterated  that  it  can  scarcely  ever  be 
met  with.  The  portion  of  the  maxilla  circumscribed  by  this  fissure  sustains  the  incisor 
teeth,  and  represents  the  incisor  or  inter-maxillary  bone  of  the  lower  animals.  In  hare- 
lip, the  solution  of  continuity  is  in  the  situation  of  this  fissure.  It  is  therefore  probable 
that  this  anterior  portion  of  the  maxillary  bone  is  developed  from  a  special  point.  Bertin 
asserts  this,  and  Meckel  and  Beclard  admit  it.  I  have  not  been  able  to  observe  such 
independent  development  at  any  period  of  foetal  life  at  which  I  have  examined  the  max- 
illary bone. 

2.  A  second  and  equally  constant  fissure  is  visible  in  the  situation  of  the  infra-orbital 
canal,  and  is  prolonged  from  the  edge  of  the  orbit  in  the  form  of  a  small  suture  to  the 
anterior  orifice  of  this  canal :  it  may  be  called  the  orbital  fissure.  This  fissure,  like  the 
preceding,  has  always  seemed  to  me  incomplete,  and  not  occasioned  by  the  separation 
of  a  distinct  piece. 

The  superior  maxillary  bone  is  one  of  the  earliest  in  making  its  appearance.  Ossifi- 
cation commences  in  it  from  the  thirtieth  to  the  thirty-fifth  day,  in  the  situation  of  the 
alveolar  arch. 

At  birth  the  superior  maxilla  has  little  height,  but  a  considerable  extent  from  before 
backward.  At  this  period  it  is  chiefly  formed  by  the  alveolar  border,  which  is  almost  con- 
tiguous to  the  floor  of  the  orbit.  The  maxillary  sinus  is  already  very  apparent.  In  the 
adult,  the  vertical  dimensions  increase  by  enlargement  of  the  sinus.  In  the  aged,  the  al- 
veolar process  becomes  flattened,  and  diminished  in  height. 

The  Palate  Bones  (Jigs.  24,  25,  26,  and  27). 

The  palate  bones  are  situated  at  the  posterior  part  of  the  nasal  fossae  and  the  palatine 
arch ;  they  are  two  in  number,  sjrmmetrical,  and  each        pig.  26.  Fig.  ar. 

composed  of  two  thin  quadrilateral  laminae,  one  of  which 
is  horizontal,  the  other  vertical,  and  which  are  joined  to- 
gether at  right  angles. 

The  horizcmtal  plate  {b  c,  figs.  26  and  27),  the  only  one 
known  to  the  ancients,  and  named  by  them  the  as  quad- 
ratum,  presents  a  superior  surface  (jif),  smooth  and  con- 


tinuous with  the  floor  of  the  nasal  fossae,  of  which  it  forms 
the  broadest  part :  an  inferior  surface  {b  c),  which  com- 
pletes the  arch  of  the  palate  :  it  is  rough,  slightly  concave 
in  front,  and  presents  behind  and  to  the  outside  a  trans- 
verse ridge  for  the  insertion  of  the  tensor  palati  muscle  ; 
and  in  front  of  this  ridge  is  the  inferior  orifice  of  the  pos- 
terior palatine  canal.     The  anterior  edge  of  this  plate  is  cut  obliquely,  so  as  to  rest  upon 
the  posterior  edge  of  the  palatine  process  of  the  superior  maxillary.     The  posterior  edge 
is  concave,  and  very  thin ;  it  gives  attachment  to  the  velum  palati.     The  internal  edge 
is  sunnounted  by  a  crest,  which  forms  one  of  the  sides  of  the  vomer,  and  terminates  be 
aind  by  a  sharp  process  (d),  which,  when  united  to  the  corresponding  part  of  the  opposite 


M  OSTEOLOGY. 

bone,  constitutes  the  posterior  nasal  spine,  which  gives  attachment  to  the  levator  muscle 
of  the  uvula  (azygos  uvulae).    The  external  edge  is  united  to  the  vertical  portion  of  the  bone. 

The  vertical  portion,  or  lamina  (a  b),  is  slightly  inclined  inward,  quadrilateral,  longer, 
broader,  and  thinner  than  the  preceding.  On  it  we  observe,  1.  An  internal  surface  (mf 
and  2,  fig.  25),  which  contributes  to  form  the  external  wall  of  the  nasal  fossae,  and  which 
presents  from  above  downward  a  horizontal  ridge  for  articulation  with  the  middle  tur- 
binated bone  ;  a  groove  belonging  to  the  middle  meatus ;  another  ridge  for  articulation 
with  the  inferior  turbinated  bone  (e  and  2,  fig.  25) ;  and  another  groove  which  makes 
part  of  the  inferior  meatus  (e/and  l,fig.  25).  2.  An  external  surface  (s  b,fig.  26,  and  p 
b,  fig.  27),  very  irregular,  which  contributes  to  form  the  bottom  of  the  zygomatic  fossa 
above,  and  which  is  rough  in  front  for  union  with  the  superior  maxillary.  This  surface 
is  traversed  by  a  vertical  groove,  which,  by  itself,  forms  £dmost  the  entire  extent  of  the 
posterior  palatine  canal  {g  g,  fig.  26).  3.  An  anterior  or  maxillary  border  {i,  fig.  27),  very 
thin  and  irregular,  which  advances  so  far  forward  as  to  contract  the  entrance  into  the 
maxillary  sinus,  and  presents  a  tongue  of  bone,  which  is  received  into  the  fissure  already 
described  as  existing  at  this  orifice.  4.  A  posterior  or  pterygoid  border  {I,  fig.  26),  which 
is  applied  to  the  inner  plate  of  the  pterygoid  process.  There  is  below,  at  the  angle  form- 
ed by  its  union  with  the  posterior  edge  of  the  horizontal  portion,  a  very  considerable  pro- 
cess for  the  size  of  the  bone  :  this  has  been  called  palatine  process,  or  tuberosity  of  the  os 
palati  (3,  fig.  25  ;  lb,  fig.  26),  but  is  better  named  pterygoid  or  pyramidal  process :  its  base 
is  continuous  with  the  test  of  the  bone,  and  from  this  point  passes  downward,  and  is,  as 
it  were,  enclosed  in  the  bifurcation  of  the  pterygoid  process  of  the  sphenoid.  Its  upper 
surface  is  traversed  by  three  grooves,  the  middle  of  which  forms  part  of  the  pterygoid 
fossa,  and  the  lateral  ones  are  rough,  and  receive  the  simimits  of  the  two  pterygoid  plates. 
Below,  the  pyreunidal  process  exhibits  the  orifices  of  the  accessory  ducts  of  the  posterior 
palatine  canal.  Externally  it  presents  a  rough  surface,  which  articulates  above  with  the 
tuberosity  of  the  superior  maxilla,  and  which  is  free  in  the  rest  of  its  extent,  and  forms 
part  of  the  zygomatic  fossa.  The  middle  of  this  process  is  grooved  in  a  vertical  direc- 
tion, for  the  posterior  palatine  canal.  5.  The  inferior  border  of  the  vertical  portion  is 
continuous  with  the  external  edge  of  the  horizontal  plate.  6.  The  superior  or  sphenmdal 
border  is  connected  with  the  sphenoid  in  almost  the  whole  of  its  extent.  It  presents  a 
deep  notch,  forming  three  fourths  or  sometimes  the  entire  spheno-palatine  foramen  {G,fig. 
25  ;  0,  figs.  26,  27 ;  n,  fig.  37),  which  corresponds  with  the  spheno-palatine  ganglion,  and 
gives  passage  to  the  vessels  and  nerves  of  the  same  name.  This  border  is  surmounted 
by  two  processes,  an  anterior  or  orbital  (4,  fig.  25  ;  a,  figs.  26,  27),  and  a  posterior  or  sphe- 
noidal {5,  fig.  25  ;  m,figs.  26,  27).  The  sphenoidal  process  is  the  broader,  particularly  at 
its  base,  but  is  not  so  elevated  as  the  anterior :  it  presents  three  facettes — an  internal, 
which  forms  part  of  the  nasal  fossa ;  an  external,  which  is  visible  in  the  zygomatic  fossa ; 
and  a  superior,  which  articulates  with  the  sphenoid,  and  presents  a  groove,  which  con- 
tributes to  form  the  ptcrygo-palatine  canal. 

The  orbital  process,  inclined  outward,  and  supported  by  a  constricted  portion  or  neck,  has 
five  facettes.  Three  of  these  are  articular,  viz.,  the  internal  {n,fig.  27),  which  is  concave,  and 
unites  with  the  ethmoid,  covering  and  completing  its  cells ;  the  anterior  {p,  fig.  27),  which 
joins  the  maxillary  bone  ;  and  the  posterior  (q,  fig.  26),  which  is  united  to  the  sphenoid  by 
certain  asperities  surrounding  a  cell,  which  exists  in  the  substance  of  the  process,  and  com- 
municates with  the  sphenoidal  sinus.  The  other  tico  are  non-articular,  viz.,  the  superior  (r, 
fig.  26),  which  forms  the  deepest  part  of  the  floor  of  the  orbit,  and  the  external  (s,  fig.  26), 
which  forms  part  of  the  zygomatic  fossa,  and  is  separated  from  the  preceding  by  ,a  small 
edge,  which  constitutes  a  portion  of  the  spheno-maxillary  fissure. 

Internal  Structure. — The  palate  bone  is  compact  throughout,  excepting  in  the  palatine 
process,  where  it  is  thick  and  cellular. 

Connexions. — The  palate  bone  articulates  with  its  fellow  on  the  opposite  side,  with  the 
maxillary,  the  sphenoid,  the  ethmoid,  the  inferior  turbinated  bone,  and  the  vomer. 

Development. — This  bone  is  developed  from  a  single  point  of  ossification,  which  ap- 
pears from  the  fortieth  to  the  fiftieth  day,  at  the  point  of  union  of  the  vertical  and  hori- 
zontal portions,  and  the  pyramidal  process.  During  its  development,  the  bone  appears 
as  it  were  crushed  down,  so  that  the  vertical  portion  is  shorter  than  the  horizontal,  and 
there  is  a  marked  predominance  in  the  antero-posterior  diameter.  This  disposition  is 
in  accordance  with  the  shortness  of  the  vertical  diameter  of  the  superior  maxilla. 


^s-^-  The  Malar  Bones  {fig.  28). 


The  malar  hones,  called  also  cheek,  jugal,  or  zygomatic  bones,  are 
situated  in  the  superior  and  lateral  part  of  the  face  :  their  form  is 
that  of  a  very  irregular  four-sided  figure.  They  have  thn  e  sur- 
faces, an  anterior,  a  posterior,  and  a  superior ;  four  borders,  and 
four  angles. 

The  anterior  or  cutaneous  surface  (a)  looks  outward,  is  convex 
and  smooth,  and  presents  the  openings  of  several  foramina  {h). 


NASAL  BONES.  55 

named  malar,  which  are  intended  for  nerves  and  vessels.  This  surface  gives  attach- 
ment below  to  the  zygomaticus  major  muscle.  It  forms  the  most  prominent  part  of  the 
cheek,  and  is  covered  only  by  the  skin  and  orbicularis  palpebrarum  muscle  :  it  is,  conse- 
quently, much  exposed  to  injury. 

The  superior  or  orbital  surface  (jb)  is  supported  by  a  thick  curved  process,  the  orbital  pro- 
cess, which  arises  from  the  bone  almost  at  a  right  angle.  This  surface  is  concave,  and 
of  small  extent :  it  forms  part  of  the  orbit,  exhibits  the  internal  openings  of  one  or  more 
malar  foramina,  and  terminates  behind  by  a  rough,  serrated  edge,  which  articulates 
above  with  the  frontal  and  sphenoid  bone,  and  below  with  the  superior  maxillary.  The 
same  maxiUary  edge  presents  in  the  middle  a  retiring,  smooth  angle,  which  constitutes 
the  anterior  extremity  of  the  spheno  maxillary  fissure. 

The  posterior  or  temporal  surface  is  concave,  and  presents  a  smooth  surface  Ijehind,  which 
contributes  to  form  the  temporal  fossa,  and  on  which  one  or  more  malar  foramina  open ; 
and  a  rough  surface  in  front,  which  unites  with  the  malar  process  of  the  superior  maxilla. 

Of  the /our  borders,  two  are  superior ;  of  these,  the  anterior  or  orbital  {d  e)  is  semi-lunar, 
rounded  and  blunt,  and  forms  the  external  third  of  the  base  of  the  orbit ;  the  posterior 
or  temporal  {e  f)  is  thin,  and  curved  like  the  letter  S,  and  bounds  the  temporal  fossa  in 
front.  Of  the  two  inferior  borders,  the  anterior  or  maxillary  (d  g)  is  very  rough  and 
articulates  with  the  maxillary  bone  ;  the  posterior  or  masseteric  (gf)  is  horizontal,  thick, 
and  tubercular,  and  gives  attachment  to  the  masseter  muscle. 

Of  the/oMr  angles,  the  superior  ox  frontal  (e),  which  is  much  elongated,  and  vertical,  is 
the  tliickest  part  of  the  bone,  and  articulates  with  the  external  angular  process  of  the 
frontal  bone  :  the  posterior  or  zygomatic  (/),  broader  and  thinner  than  the  preceding,  is 
serrated,  and  slants  downward  and  backward,  for  articulation  with  the  zygomatic  process 
of  the  temporal  bone,  which  rests  upon  it.  The  internal  or  orbital  angle  {d)  looks  in- 
ward and  forward,  is  very  acute,  and  articulates  with  the  superior  maxillary  near  the 
infra-orbitary  canal.  The  inferior  or  malar  angle  {g)  looks  downward,  is  obtuse,  and 
unites  with  the  outer  part  of  the  malar  or  jugal  process  of  the  superior  maxillary. 

Internal  Structure. — Tlie  malar  bone  is  almost  entirely  compact,  possessing  spongy 
tissue  only  in  the  anterior  and  inferior  edge,  and  in  the  part  where  the  orbital  portion  is 
given  off.  It  is  constantly  traversed  by  a  canal  called  zygomatic.  This  passeige  is  gen- 
erally simple,  but  sometimes  double  or  even  multiple,  and  opens  by  at  least  three  orifices. 
The  superior  or  orbital  orifice  is  visible  on  the  surface  of  the  same  name  ;  the  next  or 
external  zygomatic  foramen  is  on  the  cutaneous  surface  of  the  bone  ;  and  the  third  or 
internal  zygomatic  on  the  inner  surface  of  the  vertical  portion. 

Connexions. — The  malar  bone  is  articulated  with  the  superior  maxillary,  the  frontal, 
the  sphenoid,  and  the  temporal. 

Development. — It  is  developed  from  one  point  of  ossification,  which  appears  about  the 
fiftieth  day  of  fcetal  life.  The  ulterior  changes  which  it  undergoes  do  not  require  par- 
ticular notice. 

The  Masai  Bones  {fgs.  29,  30). 

The  nasal  bones  are  two  in  number,  asymmetrical,  and  very  small  in  the  human  sub- 
Fig.  29.  Fig.  30.  ject ;  they  are  closely  contiguous  to  each  other,  sometimes  united  into 
one  piece  superiorly.  They  are  situated  at  the  upper  and  middle  part 
of  the  face,  and  form,  as  their  name  indicates,  the  osseous  part  of  the 
nose,  of  which  they  constitute  the  root.  They  are  directed  obliquely 
downward  and  forward,  but  with  various  degrees  of  inclination  in  dif- 
ferent subjects ;  and  hence  the  varieties  in  the  shape  and  prominence 
of  the  middle  or  bridge  of  the  nose.  Their  figure  is  rectangular  and 
oblong  ;  they  are  thick  and  narrow  above,  broad  and  thin  below ;  and 
have  two  surfaces,  an  anterior  and  a  posterior,  and  four  edges. 
The  anterior  or  cutaneous  surface  {fig.  29)  is  covered  only  by  the  skin  and  pyramidalis 
nasi  muscle,  and  hence  the  ease  with  which  these  bones  are  fractured :  it  is  concave 
above,  flat  or  even  convex  below :  the  orifice  of  a  vascular  canal  is  always  very  distinctly 
seen,  which  is  variable  in  its  situation,  sometimes  single,  but  often  accompanied  by 
others  of  smaller  size. 

The  posterior  or  pituitary  surface  (fig.  30)  is  concave,  and  forms  the  anterior  part  of  the 
roof  of  the  nostrils :  it  is  marked  by  vascular  and  nervous  furrows,  and  in  the  fresh  state 
is  covered  by  the  pituitary  membrane. 

Of  the  four  edges,  the  superior  (a,  figs.  29,  30),  short,  thick,  and  serrated,  articulates 
with  the  nasal  notch  of  the  frontal  bone.  The  inferior  (d),  very  thin,  and  more  elonga- 
ted, has  a  slight  notch  in  the  centre  for  the  passage  of  a  nervous  filament,  and  forms 
part  of  the  anterior  orifice  of  the  nasal  fossae  :  it  unites  with  the  lateral  cartilage  of  the 
nose.  The  internal  (b)  edge  is  thick  above,  and  bevelled,  so  that,  when  approximated  to 
the  other  bone,  the  two  constitute  a  fiirrow,  in  which  the  nasal  spine  of  the  frontal  and 
the  perpendicular  lamella  of  the  ethmoid  bone  are  received.  The  external  (c)  edge  is  some- 
what longer  than  the  internal,  is  slightly  bevelled  on  the  outer  table,  and  indented  for 
articulation  with  the  ascending  process  of  the  superior  maxilla,  which  rests  upon  it. 


66  .  OSTEOLOGY. 

Connexions. — The  two  bones  are  articulated  together :  they  unite  also  with  the  frontal, 
the  ethmoid,  and  the  superior  maxiUa,  and  likewise  with  the  lateral  cartilages  cf  the 
nose  :  they  afford  passage  to  the  vessels  which  establish  a  communication  between  the 
skin  of  the  nose,  and  the  mucous  membrane  of  the  nasal  fossae. 

Internal  Structure. — The  nasal  bones  are  thick  and  cellular  in  their  upper  parts,  thin 
dnd  entirely  compact  in  their  lower,  and  are  traversed  by  nervous  and  vascular  grooves. 

Development. — The  nasal  bone  is  developed  from  one  single  osseous  point,  which  ap- 
pears before  the  end  of  the  second  month. 

Ossa  Unguis^  or  Lachrymal  Bones  {figs.  31,  32). 

These  are  the  smallest  bones  of  the  face :  they  are  thin,  like  paper,  and  have  the  trans 
Fig.  31.  Fig  32.  parence,  tenuity,  and  even  the  shape  of  a  nail,  from  which  circum- 
stance one  of  their  names  has  been  derived.  They  are  situated  at 
the  internal  and  anterior  part  of  the  orbit :  their  figure  is  irregularly 
.  quadrilateral :  they  are  two  in  number,  and,  therefore,  asymmetri- 
If  '7r  cal.  They  have  two  surfaces  and  four  edges. 
'  j,i#^  The  external  or  orbital  surface  {fig.  32)  is  divided  into  two  unequal 
parts  by  a  vertical  ridge  (a  b),  which  terminates  below  in  a  sort  of 
'^  hook.  The  portion  anterior  to  the  ridge  is  narrow,  and  marked  by 
a  porous  groove  (c),  which,  when  joined  to  the  channel  on  the  ascending  process  of  the 
superior  maxilla,  forms  the  lachrymal  groove  (hence  the  name  of  lachrymal  bone).*  The 
portion  {d)  of  the  os  unguis,  which  is  posterior  to  the  ridge,  completes  the  inner  wall  of 
the  orbit. 

The  internal  or  ethmoidal  surface  {fig.  31)  presents  a  furrow  (a'  b),  which  corresponds 
to  the  external  ridge ;  the  portion  {c')  in  front  of  the  furrow  forms  part  of  the  middle 
meatus  ;  behind  is  a  rough  surface  {d'),  which  covers  the  anterior  cells  of  the  ethmoid. 

Of  the  four  borders,  the  supcrior{a  a)  is  rough,  and  articulates  with  the  internal  angu- 
lar process  of  the  frontal  bone  ;  the  inferior  {b  h')  articulates  with  the  inferior  turbinated 
bone  by  a  small  tongue  which  passes  backward,  and  which  contributes  to  form  the  nasal 
canal,  and  with  the  internal  edge  of  the  orbital  surface  of  the  superior  maxillary.  The 
anterior  edge  {e  e')  unites  with  the  ascending  process  of  the  maxillary  bone ;  and  the 
■posterior  edge  {f  f),  slightly  denticulated,  joins  the  orbital  portion  or  lamina  papyracea 
,^mhe  ethmoid. 

^^ Connexions. — The  os  unguis  articulates  with  the  frontal,  the  ethmoid,  the  superior 
maxillary,  and  the  inferior  turbinated  bone  :  they  assist  in  the  formation  of  the  lachrymal 
sac,  the  nasal  canal,  and  the  internal  wall  of  the  orbit. 

Structure. — The  os  unguis  consists  of  a  very  thin  layer  of  compact  tissue,  and  is  the 
inost  brittle  of  all  the  bones.     It  is  of  importance  to  note  its  tenuity  and  fragility,  be- 
, Hji^aase  it  is  concerned  in  the  operation  for  fistula  lachrymalis. 

Development. — The  os  unguis  is  ossified  at  the  commencement  of  the  third  month,  from 
one  single  point. 

The  Inferior  Turbinated  or  Inferior  Spongy  Bones  (figs.  33,  34,  and  d, 

fig-  37). 

The  inferior  turbinated  bones,  so  called  on  account  of  their  curved  figure,  are  situated 

Figs  33  34.  ^^  *^^  lower  part  of  the  external  wall  of  the  nasal  fossae  {d, 

'    '  fig.  35),  below  the  ethmoid,  whence  the  name  sub-ethmoidal 

turbinated  bones.    They  are  two  in  number,  asymmetrical,  and 

their  greatest  diameter  is  directed  from  before  backward. 

They  have  two  surfaces,  two  edges,  and  two  extremities. 

The  internal  surface  {fig.  34,  and  d,fig.  37)  is  convex,  and 
looks  towards  the  nose,  which  it  sometimes  touches  when 
that  part  deviates  from  the  straight  direction ;  the  external  sur- 
face {fig.  33)  is  concave,  and  forms  part  of  the  middle  meatus. 
Both  are  rough,  and,  as  it  were,  spongy,  which  has  given  rise 
to  the  assertion  that  these  bones  form  an  exception  to  the  general  rule  of  the  spongy 
tissue  being  in  the  interior  of  bones :  this  appearance,  however,  is  owing  to  the  multi- 
plicity of  canals  intended  for  nerves,  and  more  particularly  for  the  veins  which  expand 
over  the  bone.     The  superior  or  articular  edge  {abed,  figs.  33,  34)  is  very  irregular,  and 
presents  from  before  backward,  1.  A  thin  edge  {a  b),  which  articulates  with  the  ascend- 
ing process  df  the  superior  maxilla.     2.  A  small  eminence  bearing  the  name  of  nasal  or 
lachrymal  process  (5),  which  articulates  by  its  apex  with  the  os  unguis,  and  by  its  two 
edges  with  the  two  lips  of  the  ascending  process  of  the  superior  maxillary,  to  complete  the 
nasal  canal.     3.  A  curved  pkte,  called  auricular  process  (e,  fig.  33)  by  Bertin,  who  com- 
pared it  to  the  ear  of  a  dog  :  this  plate  is  directed  downward,  and  applied  partially  upon 
the  orifice  of  the  maxillary  sinus,  which  it  assists  in  closing.     4.  Behind  this  process 

*  The  existence  of  lachryma)  bones  is  subordinate  to  that  of  the  lachrymal  secretion.     The;r  are  not  met 
with  in  those  animals  -which  bve  in  the  water,  and  which  have  neither  lachrymal  glands  nor  ptjssages. 


VOMER. INFERIOR    MAXILLA.  57 

we  find  a  thin  edge  (c  d,  figs.  33,  34),  which  articulates  with  a  small  ridge  on  the  palate 
bone.  5.  Between  the  auricular  and  the  lachrymal  processes  are  small  prominences 
which  unite  with  tlie  ethmoid. 

The  inferior  or  free  border  (a  d)  is  convex,  and  thicker  in  the  middle  than  at  its  ex 
tremities  :  it  is  separated  from  the  floor  of  the  nostrils  by  an  interval  (m  o,  fig.  37)  of  un- 
certain extent,  a  circumstance  to  be  remembered  during  the  introduction  of  instruments 
into  the  nasal  fossae. 

The  anterior  extremity  (a)  is  a  little  less  pointed  than  the  posterior  {d),  which  distin- 
guishes the  bone  of  the  right  from  that  of  the  left  side. 

Connexions. — The  inferior  turbinated  bones  articulate  with  the  superior  maxillary,  the 
palate  bones,  the  ethmoid,  and  the  ossa  unguis  :  they  have  important  relations  with  the 
inferior  orifice  of  the  nasal  canal,  which  they  defend  from  the  contact  of  foreign  bodies. 

Structure. — ^Their  external  spongy  appearance  depends  upon  the  multitude  of  canals 
with  which  their  surface  is  furrowed,  but  they  are  almost  exclusively  formed  of  compact 
tissue. 

Development. — Their  ossification  commences  about  the  fifth  mftith  of  foetal  life,  by  a 
point  situated  in  the  centre. 

The  Vomer  {jig.  35,  and  10,  fig.  22). 

The  vomer  is  so  called  from  its  supposed  resemblance  to  a  ploughshare.  It  is  situated 
in  the  median  plane,  and  forms  the  posterior  part  of  the  sep-  jVe'.  35. 

tmn  of  the  nostrils.  It  is  thin,  flat,  and  quadrilateral,  and 
has  two  surfaces  and  four  edges.  The  surfaces  are  placed 
laterally  (as  at  a,  fig.  35),  and  are  generally  plane,  but  they 
are  often  bent  to  one  side  or  the  other,  and  are  then  convex 
and  concave  in  opposite  directions  :  they  are  always  smooth, 
and  covered  by  the  pituitary  membrane,  and  present  small 
vascular  and  nervous  furrows.  The  superior  or  sphenoidal  border  {Jb,  fig.  35,  and  3,  fig. 
22)  is  the  shortest  and  thickest :  it  is  marked  by  a  deep  groove,  which  receives  the  in- 
ferior crest  of  the  sphenoid  ;  the  two  lips  of  the  groove  are  bent  outward,  and  received 
into  furrows  on  the  inferior  surface  of  the  same  bone,  and  thus  complete  a  small  chan- 
nel for  the  passage  of  vessels  and  nervous  filaments.  The  inferior  or  maxillary  (c)  bor- 
der is  the  longest,  and  is  received  into  the  furrow  which  is  formed  by  the  union  of  the 
two  palate  bones  behind  and  of  the  two  superior  maxiUary  in  front :  it  sometimes  termi- 
nates by  a  more  or  less  prominent  process  behind  the  anterior  nasal  spine.  The  anterior 
or  ethmoidal  border  {d,  fig.  35,  and  3  4,  fig.  22)  presents  the  continuation  of  the  groove  on 
the  superior  edge,  and  receives  the  inferior  bcujder  of  the  perpendicular  plate  of  the  eth- 
moid. There  is  no  groove  where  it  is  attach"  to  the  cartilaginous  septum.  The  pos- 
terior or  guttural  edge  {e,fig.  35,  and  t,  10,  fig.  22)  is  free  :  it  is  thin  and  sharp,  and  in- 
clines downward  and  forward  :  it  separates  the  posterior  openings  of  the  nasal  fossae. 

Connexions. — The  vomer  is  articulated  with  the  sphenoid,  the  ethmoid,  the  superior 
maxillary,  the  palate  bones,  and  the  cartilage  of  the  septum. 

Internal  Structure. — ^The  vomer  is  composed  of  two  very  thin  compact  laminae,  which 
are  distinct  above,  but  united  below.  Some  anatomists  have  called  these  plates  alee  of 
the  vomer. 

Development. — It  is  developed  from  one  point  of  ossification,  which  is  situated  at  the 
lower  part  of  the  bone,  and  appears  before  the  end  of  the  second  month.  It  then  pre- 
sents the  form  of  a  deep  groove,  embracing  the  cartilage  just  as,  at  a  future  period,  it 
embraces  the  sphenoidal  crest.  At  birth  the  vomer  is  still  only  a  groove ;  afterward 
this  condition  is  confined  to  the  sphenoidal  and  ethmoidal  edges  of  the  bone.  It  is  not 
uninteresting  to  note  the  peculiar  and  uncommon  manner  in  which  the  ossification  pro- 
ceeds from  the  surface  to  the  interior  of  the  cartilage. 

Inferior  Maxilla  {fig.  36). 

While,  as  w^  have  before  observed,  a  considerable  nimiber  of  bones  to  enter  into  the 
formation  of  the  upper  jaw,  the  lower  jaw  consists  of  one  pig.  36, 

bone  only.  The  inferior  maxilla  occupies  the  lower  part  of 
the  face.  From  the  number  and  importance  of  the  practi- 
cal points  connected  with  this  bone,  too  much  attention 
cannot  be  bestowed  on  the  study  of  its  form  and  connex- 
ions. It  has  the  shape  of  a  parabolic  curve,  the  two  ex- 
tremities of  which,  called  rami,  form  a  right  angle  with  the 
middle  portion  or  body. 

Of  the  body  or  middle  portion  (a). — The  body  represents  a 
curved  plate,  convex  in  front  and  concave  behind.  It  of- 
fers to  our  notice  an  anterior  and  a  posterior  surface,  and  a 
superior  and  inferior  border.  The  anterior  surface  has  in 
the  middle  a  vertical  line,  called  symphysis  menti  (c  d) ;  it 

H 


9i  OSTEOLOGY. 

marks  the  place  of  union  of  the  two  pieces  of  \jfhich  this  bone  is  composed  in  young 
subjects,  and  which,  in  a  great  number  of  animals,  remain  distinct  through  life.* 

The  mode  in  which  the  two  halves  of  the  body  of  the  inferior  maxilla  are  united, 
forming  an  arch  instead  of  an  angle,  as  in  other  animals,  constitutes  one  of  the  distinc 
live  characters  of  the  human  species  ;  and  the  vertical  direction  of  the  symphysis,  com- 
pared Avith  its  very  oblique  inclination  downward  and  backward,  or  almost  horizontal 
position  in  the  lower  animals,  is  a  no  less  characteristic  mark  of  man,  who  alone  can  be 
said  to  possess  a  chin.\ 

In  front  the  symphysis  terminates  by  a  triangular  eminence  called  mental  'process  (d). 
Behind,  it  presents  below  four  small  tubercles,  two  superior  and  two  inferior,  known  by 
the  collective  appellation  of  genial  processes  {yivcLov,  the  chin),  and  give  attachment  to 
the  genio-hyoid  and  genio-glossal  muscles. 

On  each  side  of  the  symphysis,  we  observe  on  the  anterior  or  cutaneous  surface  of  the 
body  of  the  inferior  maxilla,  1.  A  small  depression  for  the  attachment  of  muscles,  named 
mental  fossa  (e  c).  2.  A  line,  which  commences  at  the  mental  process,  passes  obliquely 
upward,  and  becomes'  continuous  with  the  anterior  edge  of  the  ramus  of  the  jaw :  it  is 
named  the  external  oblique,  or  external  maxillary  line  (c/),  and  is  also  intended  for  muscu- 
lar insertions.  3.  Above  this  line,  the  mental  foramen  (_g),  the  orifice  of  the  inferior  dental 
canal,  which  transmits  the  mental  vessels  and  nerves.  4.  The  anterior  surface  of  the 
alveolar  arch  (c  h),  marked  by  a  series  of  projections  corresponding  to  the  alveoli,  and 
separated  by  vertical  depressions,  which  point  out  the  situation  of  the  inter-alveolar  sep- 
ta. 5.  Below  the  external  oblique  line,  a  smooth  surface  (a),  separated  from  the  skin  by 
the  platysma  myoides  muscle. 

The  posterior  or  lingual  surface  is  in  some  measure  moulded  upon  the  tongue  :  it  pre- 
sents, 1.  The  mylo-hjoidcan  line  (k)  (jivXog,  dens  molaris),  called  also  internal  oblique  or  in- 
ternal tnaxillary,  which  commences  at  the  genial  processes,  and  passes  upward  and  back- 
ward, becoming  more  prominent  opposite  the  last  molar  tooth.  2.  Below  this  line,  a 
broad  but  superficial  depression,  which  lodges  the  sub-maxillary  gland.  3.  Above  the 
oblique  line,  and  near  the  symphysis,  a  fossa,  which  lodges  the  sub-lingual  gland,  and  a 
sracfoth  surface  covered  by  the  mucous  membrane  of  the  mouth  and  gums. 

These  two  lines,  the  external  and  internal  oblique,  divide  the  body  of  the  inferior  max- 
illa into  two  parts,  a  superior  or  alveolar,  and  an  inferior  or  basilar.  The  first  named 
constitutes  almost  the  entire  body  of  the  bone  in  the  foetus  and  the  infant ;  in  the  adult  it 
forms  only  two  thirds  of  the  depth  of  the  bone,  the  other  third  being  the  basilar  portion :  last- 
ly, in  the  aged,  the  alveolar  portion  almost  entirely  disappears,  and  the  basilar  only  is  left. 

The  superior  or  alveolar  border  describes  a  smaller  curve  than  the  corresponding  alveo- 
lar edge  of  the  superior  maxilla ;  so  that,  in  a  regular  conformation  of  the  parts,  the  in- 
ferior incisor  teeth  are  overlapped  by  thgl,  superior.  This  border  is  less  tliick  in  front 
than  behind,  where  it  projects  inward :  it  is  pierced  by  a  series  of  sockets  or  alveoli,  re- 
sembling those  of  the  superior  maxilla,  and,  like  them,  variable  according  to  the  kind  of 
teeth  which  they  are  intended  to  receive. 

The  inferior  border  or  base  of  the  jaw  {d  m)  is  the  thickest  part  of  the  bone  ;  it  forms 
part  of  a  larger  curve  than  the  superior  border,  so  that  the  jaw  projects  forward  in  some 
measure  at  the  lower  part :  this  projection  varies  much  in  different  subjects. 

Rami  of  the  iyiferior  maxilla  {b  b). — These  are  quadrilateral,  and  present,  1.  An  external 
surface  (A)  covered  by  the  masseter  muscle,  which  is  inserted  into  it,  especially  below, 
where  we  may  observe  depressions  and  ridges,  and  where  the  bone  itself  is  more  or 
less  bent  outward ;  in  front  of  these  ridges  is  a  slight  mark,  which  corresponds  with  the 
situation  of  the  facial  artery.  2.  An  internal  or  pterygoid  surface,  also  rough,  for  the  at- 
tachment of  the  internal  pterygoid  muscle,  and  on  which  is  observed  the  superior  orifice 
(I)  of  the  inferior  dental  canal,  which  is  wide,  and  has  a  sort  of  spine,  to  which  the  in- 
ternal lateral  ligament  of  the  temporo-maxillary  articulation  is  attached :  a  small  groove 
passes  from  this  orifice  in  the  same  direction  as  the  canal,  and  bears  the  name  of  mylo- 
hyoidean  furrow,  because  it  lodges  the  nerve  of  that  name.  3.  A  posterior  or  parotid  edge, 
which  is  round,  and  gives  attachment  below  to  the  stylo-maxillary  ligament :  it  is  era- 
braced  by  the  parotid  gland.  4.  An  anterior  edge  (r),  marked  by  a  groovi^  which  is  the 
continuation  of  the  alveolar  border ;  the  anterior  and  posterior  lips  of  this  groove  being 
formed  by  the  external  and  internal  oblique  lines.  5.  A  superior  edge,  very  thin,  and  hol- 
lowed out  into  gi  deep  notch,  called  sigmoid  notch  (n  o),  on  account  of  its  shape,  giving 
peissage  to  nerves  and  vessels.  6.  An  inferior  edge,  which  is  nothing  more  than  a  con- 
tinuation of  the  inferior  border  of  the  body  of  the  bone. 

The  angle  which  the  rami  form  with  the  body  of  the  bone  is  named  the  angle  of  the 
jaw  (m).    It  is  a  right  angle  in  the  adult,  but  very  obtuse  in  the  infant,  as  also  in  the 

*  In  serpents  these  pieces  form  a  movable  joint ;  and  as  a  similar  arrangement  obtains  between  the  two 
halves  of  the  upper  jaw,  these  reptiles  are  enabled  to  swallow  an  object  much  larger  than  their  head,  or  even 
than  their  body. 

t  It  is  interesting  to  remark  the  difference  in  the  dissection  of  the  symphysis  in  the  Caucasian  and  Ethi- 
opian varieties  of  the  human  family.  In  the  former  it  is  placed  nearly  vertically,  slightly  oblique  from  above 
to  below,  and  from  behind  to  before.  In  the  latter  it  is  oblique  from  before  to  behind,  and  in  this  respect  re- 
sembles the  conformation  in  the  inferior  animals,  more  especially  in  the  Simiie. 


INFEBIOE   MAXILLA.  ^ 

«iaruivora  and  some  of  the  rodentia^  this  disposition  enabling  its  muscles  to  act  with 
'  greater  power. 

The  rami  of  the  inferior  maxilla  are  terminated  above  by  two  processes :  the  anterior; 
called  the  coronoid  process  (n) ;  the  posterior,  named  the  condyle  (p). 

The  coronoid  process  is  triangular,  and  inclined  forward ;  broad  at  its  base,  and  pointed 
at  its  summit ;  it  gives  attachment  to  the  temporal  muscle.  The  size  of  this  process  in 
the  different  species  of  animals  bears  an  exact  and  constant  proportion,  both  to  the  depth 
and  extent  of  the  temporal  fossa,  and  to  the  strength  and  curvature  of  the  zygomatic  arch. 

The  condyle  articulates  with  the  glenoid  cavity  of  the  temporal  bone  ;  it  is  an  oblong 
eminence,  the  greatest  dizuneter  of  which  is  directed  sUghtly  inward  and  backward.  It 
is  supported  by  a  contracted  portion,  called  the  neck  of  the  condyle  {^cervix)  (o).  This  neck 
is  turned  inward  in  such  a  manner  that  the  condyle,  which  it  supports,  does  not  project 
beyond  the  external  plane  of  the  ramus  of  the  jaw ;  it  is  also  pr§tty  deeply  excavated 
internally,  to  afford  attachment  to  the  external  pterygoid  muscle.  The  neck  of  the  con- 
dyle is  the  weakest  part  of  the  inferior  maxilla. 

Connexions. — The  inferior  maxilla  articidates  with  the  temporal  bone,  and  lodges  the 
lower  range  of  teeth. 

Structure. — The  external  surface  of  the  inferior  maxUla  is  composed  of  compact  tis- 
sue ;  the  interior  of  the  bone  assumes  the  form  of  diploe,  and  is  traversed  for  a  great 
part  of  its  extent  by  the  dental  or  inferior  maxillary  canal,  which  transmits  the  vessels 
and  nerves  that  are  distributed  upon  the  teeth  of  this  jaw.  This  canal  commences  at 
the  middle  of  the  ramus,  by  a  groove  covered  with  a  fibrous  lamina,  the  only  use  of 
which,  as  it  appears  to  me,  is  to  protect  the  vessels  and  nerves,  and  to  separate  them 
from  the  internal  pterygoid  muscle.  From  this  point  it  proceeds  forward  and  inward  be- 
low the  mylo-hyoidean  line,  the  curvature  of  which  it  follows  ;  it  gradually  becomes  con- 
tracted in  diameter ;  and  in  the  situation  of  the  second  smaU  molar  or  bicuspid  tooth,  it 
divides  into  two  canals,  the  larger  of  which  is  very  short,  and  opens  upon  the  external 
surface  of  the  body  of  the  bone  at  the  mental  foramen  already  described  ;  the  other,  very 
minute,  pursues  the  original  track,  and  is  lost  near  the  middle  incisor  tooth.  In  its  pas- 
sage the  inferior  dental  canal  communicates  with  the  alveoli,  by  one,  and  sometimes  two 
foramina,  through  which  the  vessels  and  nerves  of  the  teeth  are  transmitted.  The  sit- 
uation of  the  dental  canal  varies  much  in  different  periods  of  life.  In  the  new-bom  in- 
fant, before  the  appearance  of  the  teeth,  it  occupies  the  lowest  portion  of  the  jaw ;  after 
the  second  dentition,  it  corresponds  pretty  nearly  with  the  mylo-hyoidean  line  ;  and  after 
loss  of  the  teeth,  it  runs  along  the  alveolar  border.  In  the  inferior  maxilla  of  the  old 
subject,  the  anterior  orifice  of  the  dental  canal,  or  the  mental  foramen,  is  close  to  the  su- 
perior border  of  the  bone.  The  dimensions  of  the  dental  canal  are  no  less  remarkable 
for  their  variations ;  it  is  very  large  in  the  foetus,  and  in  the  child  before  the  appearance 
of  the  second  set  of  teeth ;  it  diminishes  during  adult  age,  and  is  much  contracted  in  the 
old  subject. 

Development. — The  inferior  maxilla  is  developed  by  two  points  of  ossification,  one  for 
each  lateral  half  Antenrieth  admits,  in  addition,  three  complementary  points ;  one  for 
the  condyle,  one  for  the  coronoid  process,  and  one  for  the  angle  ;  but  I  have  never  ob- 
served them.  The  case  is  different,  however,  with  a  point  of  ossification  described  and 
figured  by  Spix,  which  forms  the  inner  side  of  the  alveolar  border,  or,  rather,  of  the  den- 
tal canal.  In  a  foetus  of  about  fifty  or  sixty  days,  I  have  seen  a  kind  of  bony  spiculum, 
which  passed  along  the  internal  surface  of  the  body  and  ramus  of  the  bone  ;  on  the  one 
half  of  the  maxillary  bone  this  spiculum  was  entirely  free  ;  but  that  of  the  other  side  ad- 
hered by  the  internal  third  of  its  length.  The  spine  which  surmounts  the  dental  canal 
is  nothing  more  than  the  extremity  of  this  bony  spiculum.  It  follows,  therefore,  that  the 
inferior  maxilla  is  developed  from  four  points  of  ossification. 

The  inferior  maxilla  takes  precedence  of  all  the  bones  of  the  head  in  its  development, 
and,  indeed,  of  all  the  bones  of  the  skeleton,  excepting  the  clavicle.  The  inferior  edge 
of  the  body  of  the  bone  appears  as  early  as  the  thirtieth  or  thirty-fifth  day ;  this  extends 
backward  to  form  the  ramus,  and  in  front  to  form  the  portion  which  supports  the  incisor 
teeth ;  it  is  probable  that  the  osseous  point  of  the  dental  caned,  mentioned  above,  appears 
at  the  same  time.  From  the  fiftieth  to  the  sixtieth  day,  each  half  of  the  bone  appears 
already  marked  by  a  groove  common  to  the  dental  canal  and  the  alveoli.  At  a  later 
period,  the  groove  becomes  very  considerable,  and  is  divided  into  alveoli  by  septa,  which 
at  first  are  incomplete,  but  afterward  become  perfect ;  the  alveoli  and  their  septa  occupy 
at  this  time  the  entire  depth  of  the  bone. 

The  point  of  ossification  described  by  Spix  is  united  to  the  rest  of  the  bone  from  the 
fiftieth  to  the  sixtieth  day.  (Spix  aflirms  that  it  remains  separate  until  the  fourth 
month.)  The  two  halves  of  the  maxilla  are  joined  together  during  the  first  year  after 
birth.  The  traces  of  this  union  exist  for  some  time,  but  are  afterward  effaced ;  in  the 
lower  animals  the  suture  remains  throughout  life. 

The  changes  which  the  inferior  maxilla  undergoes  after  birth,  relate,  1-  To  the  angle 
which  the  ramus  forms  with  the  body  of  the  bone,  which  is  very  obtuse  at  birth,  and  be- 
oomes  a  right  angle  after  devetopment  is  completed.    2.  To  the  alterations  effected  in 


60  OSTEOLOGY. 

the  booy  of  the  bone,  by  the  first  and  second  dentitions,  the  loss  of  teeth  in  liie  aged, 
and  the  subsequent  absorption  and  disappearance  of  the  alveoli. 

The  Face  in  general. 

The  fourteen  bones  which  we  have  described,  united  to  each  other,  and  joined  to  the 
bones  of  the  cranium,  form  a  piece  of  bony  sculpture,  symmetrical,  extremely  complica- 
ted, destined  to  lodge  the  organs  of  smell,  sight,  and  taste,  and  to  be  the  instrument  of 
mastication.  This  bony  sculpture  forms  the  face,  which  is  situated  below  the  cranium, 
above  the  neck,  and  in  front  of  the  vertebral  column,  from  which  it  is  separated  by  the 
pharynx,  and  is  bounded  on  each  side  by  the  zygomatic  arches. 

Dimensions  of  the  Face. 

In  order  to  form  a  just  idea  of  the  dimensions  of  the  face,  it  is  necessary  to  examine 
a  scull  cut  vertically  from  before  backward  (as  in  fig.  22).  We  then  perceive  that  the 
face  is  comprised  within  a  triangular  space,  which  is  bounded  above  by  an  irregular  line 
that  separates  it  from  the  cranium  ;  in  front  by  the  face,  properly  so  called  ;  and  below, 
by  a  line  passing  below  the  symphysis  menti.  If  a  line  be  drawn  above  the  inferior 
maxilla,  and  under  the  arch  of  the  palate,  when  prolonged  backward,  it  will  be  in  the 
plane  of  the  foramen  magnum ;  for  the  cranium  having  much  less  depth  in  front  than 
behind,  a  horizontal  line,  which  touches  the  cranium  behind,  is  separated  from  it  in  front 
by  the  entire  height  of  the  upper  jaw. 

The  vertical  diameter,  which  extends  from  the  frontal  protuberance  to  the  chin,  is  the 
longest  of  all  the  diameters  of  the  face.  It  gradually  diminishes  from  before  backward. 
The  transverse  diameter  is  of  considerable  extent  in  the  situation  of  the  cheeks,  but  di- 
minishes above  and  below  this  point.  The  antero-posterior  diameter  stretches  above  from 
the  nasal  spine  to  the  basilar  process  ;  below  it  is  greatly  contracted  ;  and  at  the  level 
of  the  chin  only  measures  the  thickness  of  the  symphysis. 

With  regard  to  the  dimensions  of  the  face  as  a  whole,  we  shall  only  refer  to  what  has 
been  already  stated  concerning  the  inverse  proportion  of  the  area  of  the  cranium,  and 
that  of  the  face,  in  different  species  of  animals.* 

The  face  represents  a  triangular  pyramid,  and  offers  for  consideration  three  surfaces 
or  regions  :  an  anterior,  a  superior,  and  an  inferior. 

Anterior  or  Facial  Region. 

The  numerous  anatomical  differences  which  this  region  presents  form  distinctive 
characters,  not  only  of  different  nations,  but  also  of  different  individuals. 

It  is  bounded  above  by  the  forehead,  below  by  the  base  of  the  inferior  maxilla,  and 
laterally  by  a  line  which  passes  along  the  external  angular  process,  the  malar  bone,  and 
the  ridge  which  separates  the  canine  fossa  from  the  tuberosity  of  the  maxilla.  In  this 
region  we  observe,  in  the  median  line,  the  nasal  eminence  ;  a  transverse  suture,  formed 
by  the  union  of  the  proper  nasal  bones  with  the  os  frontis,  the  fronto-nasal  suture ;  below 
this  suture,  the  nose,  a  pyramidal  eminence,  narrow  above  or  at  its  root,  broad  below  or 
at  its  base,  and  formed  by  two  bones,  which  are  united  together  by  juxtaposition  in  the 
median  hne,  and  externally  to  the  ascending  process  of  the  superior  maxilla.  Below 
this  eminence  is  the  anterior  orifice  of  the  nasal  fossa,  which  has  the  form  of  a  heart  on 
playing  cards,  and  presents  at  the  bottom  the  anterior  nasal  spine,  and  below  this  a  ver- 
tical suture,  the  maxillary,  the  interval  which  separates  the  middle  incisor  teeth,  the 
opening  of  the  mouth,  and  the  symphysis  menti.  On  each  side,  we  find  the  opening  or 
base  of  the  orbit,  directed  obliquely  outward,  of  an  irregular  square  form,  and  presenting 
above  the  supra-orlitary  foramen ;  below,  the  infra-orhitary  foramen ;  on  the  outside,  the 
fronto-jugal  suture ;  and,  on  the  inside,  the  fronto-maxillary  suture.  Below  the  opening 
of  the  orbit  is  the  canine  fossa,  then  the  alveoli  and  teeth  of  the  two  jaws,  the  extemsd 
oblique  line,  the  mental  foramen,  and  the  base  of  the  inferior  maxilla. 

Superior  or  Cranial  Region. 
This  region  is  so  united  with  the  inferior  surface  of  the  cranium,  that  the  scull  and 
the  superior  maxilla  form  only  one  piece,  and  cannot  be  removed  from  each  other.  It 
presents,  in  the  median  line,  counting  from  behind  forward,  the  articulation  of  the  vomer 
with  the  sphenoid,  in  which  articulation  there  is  a  mutual  reception  of  parts,  the  sphe- 
noidal crest  being  received  between  the  laminae  of  the  vomer,  and  these,  in  their  turn, 
being  lodged  in  corresponding  fissures  in  the  sphenoid ;  the  articulation  of  the  vomer 
with  the  posterior  edge  of  the  perpendicular  plate  of  the  ethmoid ;  the  articulation  of 
this  perpendicular  plate  with  the  nasal  spine  of  the  frontal  bone  ;  and  the  articulation  of 
this  spine  with  the  proper  bones  of  the  nose.  On  each  side,  proceeding  from  within  out- 
ward, we  observe,  1.  The  roof  of  the  nasal  fossae,  formed  behind  by  the  inferior  surface 
of  the  body  of  the  sphenoid ;  in  the  middle  by  tlie  cribriform  plate  of  the  ethmoid  ;  and 
in  front  by  the  pusterior  surface  of  the  nasal  bones.     2.  More  externally,  the  base  of  the 

'  Vide  of  the  cranium  in  general ;  of  the  facial  angle  of  Camper ;  the  occipital  angle  of  Danbenton,  and  the 
measurement  of  Cuvier,  p.  45 


THE    FACE   IN    GENERAL.  01 

pterygoid  processes,  the  articulation  of  the  palate  bone  with  the  sphenom,  the  pterygo- 
palatine canal,  and  the  spheno-palatine  foramen.  3.  The  articulation  of  the  lateral  mass- 
es of  the  ethmoid  with  the  sphenoid  behind,  and  with  the  frontal  bone  in  front.  4.  The 
articulation  of  the  internal  angular  process  of  the  frontal  bone  with  the  os  unguis.  5.  The 
articulation  of  the  nasal  notch  of  the  frontal  bone  with  the  ascending  process  of  the  su- 
perior maxilla,  and  the  proper  bones  of  the  nose.  6.  More  externally  still,  the  roof  of  the 
orbit,  bounded  externally  by  the  articulation  of  the  frontal  with  the  malar  bone  and  the 
sphenoid,  and  by  the  sphenoidal  fissure.  7.  The  anterior  surface  of  the  great  wing  of 
^  the  sphenoid,  which  forms  the  largest  portion  of  the  external  wall  of  the  orbit ;  8.  Out- 
side the  orbit,  the  zygomatic  arch. 

Inferior  or  Guttural  Region. 

This  region  forms  part  of  the  pharynx  and  cavity  of  the  mouth.  It  presents  from  be- 
hind forward,  1.  A  vertical  portion;  2.  A  horizontal  portion  ;  and,  3.  Another  vertical 
portion. 

The  vertical  portion  {fig.  21)  exhibits  in  the  median  line  the  posterior  edge  of  the  sep- 
tum narium,  formed  by  the  vomer ;  the  posterior  extremity  of  the  articulation  of  the  vo- 
mer with  the  sphenoid  (o,  fig.  21) ;  and  the  posterior  nasal  spine.  On  each  side,  the  pos- 
terior opening  of  the  nasal  fossa  {k  o,  y),  which  is  quadrilateral,  longer  in  its  vertical  than 
in  its  transverse  diameter,  and  formed  internally  by  the  vomer,  externally  by  the  ptery- 
goid process  (r),  above  by  the  sphenoid  united  with  the  palate  bone,  and  below  by  the 
ualate  bone.  More  externally  is  the  pterygoid  fossa  (r),  formed  by  the  sphenoid,  and  a 
small  part  of  the  palate  bone.  Still  more  externally,  we  find  a  deep  fossa,  or,  rather,  a 
large  space  bounded  internally  by  the  external  plate  of  the  pterygoid  process  and  th#  tu- 
berosity of  the  maxillary  bone,  and  externally  by  the  ramus  of  the  inferior  maxilla ;  it  is 
known  by  the  name  of  the  zygomatic  fossa. 

The  horizontal  portion  is  the  aixh  of  the  palate  {i  x  y,  fig.  21).  It  is  of  a  parabolic  form, 
extremely  rough,  and,  in  the  fresh  state,  covered  by  the  palatine  mucous  membrane.  It 
is  constituted  by  the  palatine  processes  of  the  maxillary  bones  (x),  and  by  the  horizontal 
portions  of  the  palate  bones  (y),  and  presents,  in  consequence,  a  crucial  suture,  at  the  cen- 
tral point  of  which  the  vomer  is  attached :  hence  the  piece  of  anatomical  nicety  which 
consisted  in  Eisking  at  what  part  of  the  skeleton  it  is  possible  to  touch  five  bones  at  once 
with  the  point  of  a  needle.  The  arch  of  the  palate  is  pierced  by  several  foramina ;  we 
find  here  the  inferior  opening  of  the  anterior  palatine  canal  (1),  which  is  single  below,  but 
double  above,  so  as  to  open  into  each  nostril  separately  ;  the  posterior  palatine  canals  (2), 
which  open  at  the  posterior  and  external  part  of  the  arch  of  the  palate  ;  and  a  groove, 
which  runs  along  the  external  edge  of  the  arch,  and  lodges  the  posterior  palatine  vessels 
and  ner\'es  at  their  exit  from  their  canals. 

The  third  portion  is  also  vertical :  it  presents,  1.  In  the  median  line,  the  suture  of  the 
two  superior  maxillary  bones,  the  interval  between  the  middle  incisor  teeth  of  each  jaw, 
the  symphysis  menti,  and  the  genial  processes.  2.  On  each  side,  the  posterior  surface 
of  the  alveolar  border  of  the  upper  jaw,  and  the  two  rows  of  teeth  which  lie  across  each , 
other  like  the  blades  of  scissors  in  the  middle,  but  meet  posteriorly.  3.  The  posterior 
surface  of  the  inferior  maxilla,  the  internal  oblique  line,  the  sub-lingual  and  sub-maxillary 
fossae,  and,  lastly,  the  base  of  the  inferior  maxilla. 

Zygomatic  or  Lateral  Regions. 

These  regions  are  bounded  above  and  on  the  outside  by  the  zygomatic  arch ;  above 
and  on  the  inside  by  the  transverse  ridge  which  separates  the  temporal  from  the  zygo- 
matic fossa.  They  present  first  a  plane  surface,  formed  by  the  ramus  of  the  inferior 
maxilla  ;  when  this  part  is  removed,  we  observe  the  zygomatic  fossa,  the  superior  wall  of 
which  is  formed  by  the  inferior  surface  of  the  great  wing  of  the  sphenoid,  the  anterior 
by  the  maxillary  tuberosity,  the  internal  by  the  outer  plate  of  the  pterygoid  process,  and 
the  external  by  the  ramus  of  the  inferior  maxilla.  The  posterior  and  inferior  walls  are 
wanting. 

At  the  bottom  of  this  fossa,  between  the  maxiUary  bone  and  the  anterior  surface  of 
the  pterygoid  process,  is  a  large  vertical  fissure,  named  by  Bichat  the  pterygo-maxillary 
fissure ;  this  opening  leads  into  a  sort  of  fossa,  denominated  by  the  older  anatomists  bot- 
tom of  the  zygomatic  fossa,  and  by  Bichat  spheno-maxillary  fossa,  which  it  is  important  to 
study  carefully,  because  five  foramina  or  canals  open  into  it,  viz.,  three  behind  ;  thefora' 
men  rotundum,  the  vidian  or  pterygoid,  and  the  ptery go-palatine  canals  :  a  fourth  on  the  in- 
side, the  spheno-palatine ;  and  a  fifth  below,  the  superior  orifice  o{the posterior  palatine  canal. 

Lastly,  the  spheno-maxillary  fossa  presents,  at  the  union  of  its  superior  with  its  ante- 
rior wall,  the  spheno-maxillary  fissure  [fig.  21,  before  3),  which,  on  the  one  hand,  makes 
an  acute  angle  with  the  sphenoidal  fissure  (or  foramen  lacerum  orbitale),  and,  on  the 
other,  a  right  angle  with  the  pterygo-maxillary  fissure.  The  spheno-maxillary  fissure, 
which  is  traversed  solely  by  some  nerves  and  vessels,  is  formed  internally  by  the  max- 
illary and  palate  bones,  externally  by  the  sphenoid,  and  at  its  anterior  extremity,  which 
is  very  broad,  it  is  completed  by  the  malar  bone. 


62  OSTEOLOGY. 

■'  Cavities  of  the  Face.  ---i.  >*»..:•,. 

TTie  study  of  those  bones  which  we  have  been  engaged  in  examining  has  made  us  ac- 
quainted with  the  existence  of  a  great  number  of  cavities,  which  considerably  augment 
the  size  of  the  face,  and  multiply  its  internal  surfaces,  without  proportionally  increasing 
the  weight. 

All  the  cavities  of  the  face  may  be  reduced  to  three  principal :  viz.,  1.  The  orbital  cav- 
ities ;  2.  The  nasal  fossae,  of  which  ail  the  sinuses  are  dependances ;  and,  3.  The  buc- 
cal cavitv,  or  mouth. 

The  Orbits. 

These  cavities,  two  in  number,  have  the  form  of  quadrangular  pyramids,  the  axes  of 
which,  prolonged  backward,  would  intersect  each  other  in  the  situation  of  the  sella  tur- 
cica. It  shoidd,  at  the  same  time,  be  remarked,  that  the  internal  wall  of  the  orbit  does 
not  participate  in  this  obliquity,  but  is  directed  straight  from  before  backward.  We  have 
to  consider  in  each  orbit,  a  superior,  an  inferior,  an  external,  and  an  internal  wall ;  four 
angles  which  correspond  to  the  intersection  of  these  surfaces  ;  a  base  and  an  apex. 

The  superior  wall,  or  roof  of  the  orbit,  formed  by  the  frontal  bone  in  front,  and  by  the 
orbital  or  lesser  wing  of  the  sphenoid  behind,  is  concave,  and  presents  from  before  back- 
ward, 1 .  Towards  the  outside,  the  lachrymal  fossa.  2.  On  the  inside,  the  slight  depres- 
sion in  which  the  pulley  for  the  superior  oblique  muscle  is  attached.  3.  The  suture  be- 
tween the  lesser  wing  of  the  sphenoid  and  the  orbital  plate  of  the  frontal.bone.  4.  The 
foramen  opticum. 

The  inferior  wall,  or  floor,  forms  a  plane  inclined  outward  and  downward,  and  pre- 
senll  from  before  backward,  1.  The  infra-orbital  canal.  2.  A  suture  which  marks  the 
union  of  the  malar  bone  with  the  superior  maxilla.  3.  The  orbital  surface  of  the  superior 
maxilla.  4.  A  suture  which  marks  the  union  of  the  superior  maxilla  with  the  palate  bone. 
5.  The  orbital  facette  of  the  palate  bone. 

The  external  wall,  formed  by  the  sphenoid  and  the  malar  bone,  presents  an  almost  ver- 
tical suture,  which  indicates  internally  the  spheno-jugal  suture. 

The  internal  wall,  formed  by  the  os  unguis,  the  ethmoid,  and  the  sphenoid,  presents 
two  vertical  sutures  :  in  front,  that  which  unites  the  os  unguis  to  the  ethmoid,  and  be- 
hind, that  which  unites  the  ethmoid  to  the  sphenoid.  In  front  of  these  sutures  is  the 
lachrymal  groove,  formed  by  the  union  of  the  os  unguis  and  the  ascending  process  of  the 
superior  maxilla ;  at  the  lower  part  of  this  groove  we  find  the  wide  and  very  oblique  ori- 
fice of  the  nasal  canal  or  duct,  which  opens  into  the  middle  meatus  of  the  nose,  and  es- 
tablishes a  direct  communication  between  the  orbital  and  nasal  cavities. 

Of  the  four  angles,  two  are  superior  and  two  infetior.  Of  the  two  superior,  one  is  in- 
ternal, the  other  external.  The  external  superior  angle  presents  the  sphenoidal  fissure 
behind,  and  the  inner  aspect  of  the  spheno-frontal  and  fronto-jugal  sutures. 

The  internal  superior  angle  presents  the  suture  of  union  of  the  frontal  bone  with  the 
ethmoid  behind,  and  with  the  os  unguis  in  front.  The  orifices  of  the  two  internal  orbital 
foramina  are  seen  in  the  situation  of  this  suture. 

Of  the  two  inferior  angles,  the  external  presents  the  spheno-maxillary  fissure,  a  portion 
of  the  malar  bone,  and  the  opening  of  the  jugal  canal.  The  internul  presents  an  uninter- 
rupted horizontal  suture,  which  unites  in  front  the  maxillary  bone  to  the  os  unguis ; 
more  posteriorly,  the  maxillary  bone,  and  then  the  palate  bone,  to  the  ethmoid.  The 
base  of  the  orbit  is  cut  obhquely  from  within  outward,  and  from  before  backward  ;  its  ver- 
tical diameter  is,  for  the  most  part,  quite  perpendicular  to  the  horizon,  but  is  sometimes 
rendered  slightly  oblique  by  the  projection  of  the  frontal  sinuses.  At  the  apex  of  the  or 
bit  is  the  union  of  the  sphenoidal,  the  spheno-maxillary,  and  pterygo-maxillary  fissures. 

The  Nasal  Fossa. 

These  fossae  are  two  in  number,  separated  from  each  other  by  a  vertical  septum  di- 
rected from  before  backward ;  they  are  situated  in  the  middle  of  the  face,  and  are  pro- 
longed into  the  interior  of  several  of  the  bones  of  the  face  and  cranium  by  means  of  the 
cavities  called  sinuses.  To  describe  their  situation  more  exactly,  we  may  say  that  they 
are  placed  below  the  anterior  and  middle  part  of  the  base  of  the  cranium,  above  the  cav- 
ity of  the  mouth,  between  the  orbits,  and  the  canine  and  zygomatic  fossae  of  each  side. 
In  order  to  have  an  exact  idea,  either  of  the  dimensions  or  the  shape  of  the  nasal  fossae, 
it  is  necessary  to  have  recourse  to  horizontal  and  vertical  sections,  of  which  the  latter 
should  be  made  both  from  before  backward  and  from  side  to  side. 

With  regard  to  their  dimensions,  the  nasal  fossae  (see  figs.  22  and  37)  present,  1.  A 
vertical  diameter,  larger  in  the  middle  than  before  or  behind.  2.  A  transverse  diameter 
much  shorter  than  the  other  two,  and  gradually  contracted*  from  the  lower  to  the  upper 
part,  on  account  of  the  obliquity  of  the  external  wall.  3.  An  antero-posterior  diameter, 
which  measures  the  whole  of  the  interval  between  the  anterior  and  posterior  openings 
of  the  nares. 

*  This  pro^essivo  contraction  of  the  nasal  fosss  from  below  upward,  and  the  obliquity  of  the  externa! 
wall,  ought  to  be  remembered  during  the  introduction  of  instruments  into  the  nose. 


THE    FACE    IN    GENERAL.  ^ 

■  The  nasal  fossae  have  a  horizontal  direction,  but  are  nevertheless  slightly  inclined 
backward  and  downward  ;  this  is  caused  by  the  sloping  of  the  inferior  wall  and  the  ob- 
liquity of  the  body  of  the  sphenoid,  which  fonns  part  of  the  superior  wall.  They  are 
irregular  cavities,  and  have  four  walls ;  a  superior,  an  inferior,  an  internal,  and  an  ex- 
ternal ;  and  two  orifices,  an  anterior  and  a  posterior. 

The  superior  wall  or  roof  of  the  nasal  fosses  presents  a  concavity  looking  downward :  it 
o  :  :rraefl  1  In  front  by  the  proper  bones  of  the  nose,  and  in  a  small  degree  by  the  na- 
sal spine  of  tne  frontal  bone.  2.  In  the  middle,  by  the  cribriform  plate  of  the  ethmoid. 
3.  Behind,  by  the  body  of  the  sphenoid.  In  this  wall  are  two  transverse  sutures,  name- 
ly :  before,  the  suture  which  indicates  the  union  of  the  nasal  and  frontal  bones,  and  be- 
hind, that  which  marks  the  union  of  the  ethmoid  and  sphenoid.  At  the  back  part  of  this 
wall  the  opening  of  the  sphenoidal  sinus  is  seen. 

The  inferior  wall  or  floor,  much  broader  but  shorter  than  the  superior,  presents  a  trans- 
verse concavity ;  it  is  directed  from  before  backward,  and  slightly  from  above  downward, 
which  arrangement  concurs  in  determining  the  obliquity  of  the  nasal  fossae.  It  is  form- 
ed, in  front  by  the  superior  maxilla ;  behind,  by  the  palate  bone  ;  a  transverse  suture 
marks  the  union  of  these  bones.  Near  its  anterior  extremity,  and  at  the  side  of  the  me- 
dian line,  the  floor  of  the  nasal  fossa?  shows  the  superior  orifice  of  each  branch  of  the  an- 
terior palatine  canal  {g,  fig.  22,  and  o,  fig.  37). 

The  internal  wall  (see  fig.  22)  formed  by  the  septum  is  generally  flat,  but  sometimes 
concave  or  convex,  according  as  it  is  bent  to  one  or  the  other  side.* 
We  find  here  the  suture  which  indicates  the  union  of  the  vomer  with  the  perpendicu- 
'  lar  plate  of  the  ethmoid  (3  4,  fig.  22) ;  the  septum  in  the  skeleton  is  deeply  notched  in 
front,  and  this  notch  (14  8),  which  is  formed  above  by  the  perpendicular  plate  of  the  eth- 
moid, and  below  by  the  vomer,  is  occupied  in  the  fresh  state  by  a  cartilage,  called  the 
cartilage  of  the  septum. 

The  external  wall  {fig.  37),  remarkable  for  its  anfractuosities,  is  formed  by  the  ethmoid 
(,6  c),  the  OS  unguis,  the  palate  bone  (m  y),  the  superior  maxillary  p^    37_ 

(*  ic  o),  and  the  inferior  turbinated  bone  (d).  It  presents  from 
above  downward,  1.  The  superior  turbinated  bone,  superior  concha, 
or  concha  of  Morgagni  (i),  in  front  of  which  is  a  rough  square  sur- 
face. 2.  The  superior  meatus  (between  b  and  c),  at  the  back  part 
of  which  we  find  the  spheno-palatine  foramen  (n),  and  the  open- 
ing of  the  posterior  ethmoidal  cells.  3.  Below  the  superior  mea- 
tus, the  middle  turbinated  bone,  or  middle  concha  (c).  4.  Below,  the 
middle  meatus  (between  c  and  d),  at  the  back  of  which  is  the  open- 
ing of  the  maxillary  sinus  already  described  {s-ee  maxillary  bone, 
Jig.  25) ;  and  in  front,  the  infundibulum  (s,  fig.  37),  which  leads 
into  the  anterior  ethmoidal  cells.  5.  The  inferior  turbinated  bone, 
or  inferior  concha  (d).  6.  The  inferior  meatus  (m  o),  in  which  we 
find  the  inferior  orifice  of  the  nasal  canal. 

The  anterior  and  posterior  openings  of  the  nasal  fossae  have  been  described  with  the 
anterior  and  inferior  regions  of  the  face. 

General  DevelopTnent  of  the  Face. 

The  development  of  the  face  is  not  effected  solely  by  an  equable  increase  of  its  dimen- 
sions ;  for  certain  regions  are  at  one  period  of  life  predominant,  at  another  period  rela- 
tively smaller,  which  circumstances  give  rise  to  very  characteristic  differences  of  form 
at  different  ages. 

State  of  the  interior  Region  of  the  Face  at  different  Periods  of  Life. 

In  the  Foetus. — The  upper  part  of  the  face  shows  a  remarkable  predominance,  depend- 
ant upon  the  early  development  of  the  frontal  bone  and  the  great  capacity  of  the  orbits. 

The  middle  portion,  or  the  superior  maxilla,  on  the  contrary,  is  very  much  contracted 
by  the  absence  of  the  maxillary  sinus  and  canine  fossa ;  the  vertical  dimensions  of  the 
superior  maxilla  and  of  the  palate  bone  are  so  small,  that  the  edge  of  the  orbit  and  the 
alveolar  border  are  almost  contiguous.  We  should  mention  here  that  the  prominence 
of  the  alveolar  border,  which  still  encloses  all  the  germs  of  the  teeth,  is  the  principal 
cause  of  the  absence  of  the  canine  fossa.  Lastly,  the  inferior  maxilla  is  contracted  in 
its  vertical  diameter,  like  the  superior,  and,  like  it,  presents  a  decided  prominence  in 
front,  by  reason  of  its  enclosing  the  germs  of  the  teeth  in  the  alveoli.  The  inclusion  of 
the  dental  germs  also,  by  causing  the  alveolar  border  to  project,  produces  a  degree  of 
obliquity  downward  and  backward  of  the  symphysis  ;  to  these  causes  of  the  small  extent 
of  the  vertical  dimension  of  the  face,  we  must  add  also  the  inconsiderable  height  of  the 
ethmoid  at  this  period. 

*  Sometimes  the  deviation  of  the  septum  is  so  considerable  that  the  internal  touches  the  external  wall,  and, 
consequently,  there  is  great  difficulty  in  th«  passage  of  the  air.  This  circumstance  has  given  nse  ir  some 
cases  to  a  suspicion  of  the  existence  of  polypus. 


i 


64  OSTEOLOGV. 

The  transverse  dimensions  of  the  face  are  very  considerable  at  the  level  of  the  orbits , 
at  the  lower  part  of  the  face,  on  the  contrary,  they  are  proportionally  much  less  than  in 
the  adult. 

The  characteristics,  then,  of  the  face  of  the  foetus  are,  1.  The  smallness  of  its  verti- 
cal dimension.     2.  The  predominance  in  size  of  its  upper  over  its  lower  part. 

In  the  adult,  the  development  of  the  maxillary  sinus,  the  widening  and  vertical  exten- 
sion of  the  alveolar  arches,  give  to  the  face  the  expression  which  characterizes  it  at  that 
period  of  life. 

In  the  aged,  the  loss  of  the  teeth,  and  the  disappearance  of  the  alveolar  edge,  partly 
restore  to  the  face  the  expression  which  it  had  in  tlie  foetus  ;  but  the  elongation  and  prom- 
iuence  of  the  chin,  which,  from  the  diminution  of  the  vertical  diameter,  approaches  the 
nose,  and  the  symphysis  of  which  is  now  oblique  from  behind  forward  and  downward, 
impress  upon  it  a  peculiar  character.  The  obliquity  of  the  cliin,  just  mentioned,  is  pre- 
cisely the  reverse  of  that  which  exists  in  the  foetus. 

State  of  the  Lateral  Regions  in  different  jjges. 
These  regions  undergo  the  fewest  changes  of  all ;  for  if,  on  the  one  hand,  the  devel- 
opment of  the  maxillary  sinus  tends  to  increase  the  prominence  of  the  maxillary  tuber- 
osity in  the  adult,  on  the  other,  the  inclusion  of  the  dental  germs  in  the  superior  max- 
illa, during  foetal  life,  compensates  for  the  want  of  the  sinus. 

State  of  the  Posterior  Region  of  the  Face  at  different  ^ges. 

In  the  guttural  portion,  this  region  presents,  in  the  foetus  and  the  infant,  the  foUowmg 
circumstances  :  the  posterior  borders  of  the  rami  of  the  jaw  are  very  oblique,  instead  oi 
being  almost  vertical,  as  in  the  adult ;  the  pterygoid  processes,  and  the  posterior  nasal 
openings,  are  also  directed  very  obliquely  downward  and  forward,  instead  of  vertically, 
on  account  of  the  absence  as  yet  of  the  maxillary  sinus,  which,  during  its  development, 
carries  them  backward.  From  the  obliquity  of  the  posterior  border  of  the  ramus  of  the 
jaw,  it  follows  that  the  articular  surface  of  the  condyle  which  surmounts  it  looks  back 
ward  instead  of  upward. 

In  the  horizontal  or  palatine  portion,  the  inferior  region  of  the  face  has  proportionally 
less  extent  from  before  backward  than  in  the  adult,  on  account  of  the  obliquity  of  the 
pterygoid  process,  and  the  slight  development  of  the  maxillary  sinus.  We  perceive, 
then,  how  great  an  influence  the  varying  conditions  of  these  sinuses  exercise  over  the 
whole  configuration  of  the  face,  at  the  different  periods  of  life. 

It  may  be  easily  conceived  that  the  cavities  of  the  face  must  undergo  important  chan 
ges  during  these  alterations  in  the  shape  of  the  face  which  we  have  been  describing. 
The  most  remarkable  is  the  tardy  development  of  the  nasal  fossae  compared  with  that 
of  the  orbits.  It  may  even  be  said  that  they  proceed  in  an  inverse  ratio.  The  orbital 
cavity,  intended  to  receive  the  globe  of  the  eye,  which  is  already  highly  developed  at  the 
time  of  birth,  is  of  great  capacity.  This  magnitude  it  owes  entirely  to  the  rapid  growth 
of  the  frontal  and  sphenoid  bones  ;  because  the  malar  bone  and  the  superior  maxilla  con- 
tribute but  little  towards  it,  and  the  height  of  the  ethmoid  is  so  small,  that  the  vertical 
diameter  of  the  orbit,  which  depends  upon  that  of  the  ethmoid,  is  less  considerable  than 
its  transverse  diameter.  The  nasal  fossas,  which  are  very  small  in  the  foetus,  gradually 
acquire  an  increased  extent  of  surface,  by  the  growth  in  height  of  the  ethmoid,  the  pal- 
ate bone,  the  superior  maxillary,  and  the  vomer,  and  by  the  augmented  size  of  the  turbi- 
nated bones  ;  and  their  surface  is  still  farther  extended  by  the  enlargement  of  the  max- 
illary, sphenoidal,  and  frontal  sinuses,  and  the  ethmoidal  cells.  The  development  of 
the  frontal  sinus,  it  may  be  observed,  is  owing  chiefly  to  the  separation  of  the  two  tables 
of  the  bone,  the  anterior  of  which  is  almost  always  thrown  forward,  the  posterior  remain- 
ing stationary.  There  are,  however,  some  examples  on  record,  in  which  it  was  evident 
that  the  sinus  was  formed  almost  exclusively  by  the  retrocession  of  the  posterior  table. 


THE  THORAX,  OR  CHEST. 

The  Sternum. — Ribs. — Costal  Cartilages. — The  Thorax  in  general. — Development. 

The  thorax  {■&upa^,  the  chest)  is  a  sort  of  bony  cage  intended  to  contain  and  protect 
the  principal  organs  of  respiration  and  circulation.  The  parts  which  enter  into  its  com- 
position are  twelve  dorsal  vertebrae  behind,  the  sternum  in  front,  and  twelve  flexible 
bones  named  ribs,  on  each  side.  We  have  already  described  the  dorsal  vertebrae,  and 
have  now,  therefore,  only  to  notice  the  sternum  and  the  ribs. 

The  Sternum  (a  b  c,fig.  38). 
The  sternmn,  so  named  from  the  Greek  word  arepvov,  the  breast,  is  a  kind  of  flat- 
tened, symmetrical,  bony  column,  which  occupies  the  anterior  and  middle  part  of  the 
thorax.    It  is  situated  between  the  ribs,  which  support  it  like  props.    The  clavicles, 


6S 

and  through  them  the  upper  extremities,  rest  upon  its  upper  part  as  a  basis,  during  their 
movements.  The  sternum  is  not  immovably  fixed  in  its  place;  it  is  raised  and  de- 
pressed, as  we  shall  point  out  in  describing  the  mechanism  of  the  thorax. 

The  length  of  the  sternum,  which  is  proportionally  smaller  in  the  female  than  in  the 
male,  varies  from  5^  to  7i  inches.  At  its  upper  part  its  breadth  is  from  IHo  2  inches ; 
it  then  becomes  contracted,  then  again  expands,  and  terminates  below  in  a  very  nar- 
row extremity.  Its  thickness  above  is  about  6  lines  ;  at  its  lower  part  it  is  much  thin- 
ner, never  exceeding  3  hues. 

With  regard  to  figure,  the  sternum  was  compared  by  the  ancients  to  the  sword  of  a 
gladiator,  and  from  this  have  arisen  the  denominations  given  to  its  various  parts.  The 
upper  part  {a),  which  is  broadest,  has  been  called  the  handle  (manubrium) ;  the  middle 
part  (J),  the  body  {mucro) ;  and  the  lower  extremity  (c),  the  poini ;  xipJioid  appendix  {pro- 
cessus cnsiformis).  This  division  of  the  bone  into  three  parts  has  been  retained  by  some 
modern  anatomists,  who  describe  the  three  pieces  of  the  sternum  separately  as  so  many 
distinct  bones.  We  shall  adhere  to  it  only,  however,  in  speaking  of  the  development  of 
the  bone. 

The  sternum  presents  two  surfaces,  two  borders,  and  two  extremities. 

1.  The  anterior  or  cutaneous  surface  is  shghly  convex,  and  forms  an  oblique  plane  down- 
ward and  forward ;  it  presents  three  or  four  projecting  transverse  lines,  which  are  tra- 
ces of  the  union  of  the  original  pieces  of  the  bone,  and  divide  it  into  surfaces  of  unequal 
size.  The  line  which  marks  the  union  of  the  first  two  pieces  of  the  bone  is  the  most 
remarkable ;  it  causes  a  projection  of  variable  size  in  different  individuals,  which  has 
been  sometimes  mistaken  for  a  fracture  or  exostosis.  At  the  lower  part  of  this  surface, 
we  find  in  some  subjects  a  foramen  which  perforates  the  bone  :  sometimes,  in  place  ot 
this  foramen,  there  is  a  considerable  aperture,  to  which  much  importance  has  been 
attached,  as  affording  a  proof  of  the  primitive  separation  of  the  bone  in  the  median  hne. 
The  existence  of  this  opening  explains  how  purulent  matter,  deposited  behind  the  ster- 
num, may  in  certain  cases  make  its  way  outward  without  any  absorption  of  the  bone. 
The  anterior  surface  of  the  sternum  is  covered  by  the  skin,  and  an  interlacement  of 
very  numerous  aponeurotic  fibres. 

2.  The  posterior,  mediastinal,  or  cardiac  surface  (a  b  c),  is  slightly  concave  from  above 
downward,  and  presents,  in  young  subjects,  lines  (e  e)  corresponding  to  those  which 
occupy  the  anterior ;  but  all  which,  excepting  the  one  between  the  first  and  second  pieces 
of  the  bone,  are  effaced  at  a  more  advanced  age.  This  surface  is  in  relation  with  many 
organs  contained  in  the  chest,  and  especially  the  heart,  in  front  of  which  the  sternum 
forms  a  kind  of  shield.*    At  the  lower  part  of  this  surface  are  several  nutritious  foramina. 

3.  The  borders,  very  thick  and  sinuous,  present  seven  articular  cavities  {d  d,  &c.),  sep- 
arated from  each  other  by  semilunar  notclies,  which  are  longer  above  than  below,  where 
the  facettes  closely  approach  one  another.  The  uppermost  of  these  seven  cavities  is 
shallow,  triangular,  and  at  an  early  age  becomes  ingrained  with  the  cartilage  of  the  first 
rib ;  those  which  follow  are  d^Sfttu  angular,  and  situated  at  the  extremities  of  each  of 
the  lines  (e  e)  above  mentionfd:^J^ey  are  all  intended  to  articulate  with  the  cartilages 
of  the  first  seven  ribs.  WhenjgiSmined  in  a  dried  specimen,  they  appear  more  angiSar 
and  deeper  in  proportion  to  the^buth  of  the  subject. 

4.  The  superior  or  clavicular  extremity  is  the  broadest  and  thickest  part  of  the  whole 
bone,  presenting  a  notch,  transversely  concave,  which  bears  the  name  of  fourchette  (/) 
of  the  sternum  (or  semilunar  notch) ;  on  each  side  {g  g)  is  an  oblong  articular  surface, 
concave  from  without  inward,  convex  from  before  backward,  articulated  with  the  clav- 
icle, and  surrounded  with  inequalities  for  the  insertion  of  muscles  and  ligaments.  It 
frequently  happens  that  the  two  clavicular  facettes  are  not  at  the  same  height ;  a  fact 
which  was  noticed  by  Morgagni,  and  which  I  have  attributed  to  the  unequal  wearing  of 
the  two  articular  surfaces. 

5.  The  inferior  or  abdomj^nal  extremity  is  formed  by  the  xiphoid  appendix  (c)  {^i^o^,  a 
sword),  called  also  xiphoid'^  ensiform  cartilage,  because  it  often  remains  cartilaginous  to 
Hdult  age.  In  length,  shape,  and  direction,  it  presents  numerous  varieties ;  it  is  fre- 
quently bifid,  sometimes  pierced  by  a  foramen,  and  is  accasionally  bent  forward,  or  to 
one  side,  and,  in  certain  cases,  much  depressed :  its  summit  gives  attachment  to  an  ap- 
oneurotic structure,  called  the  linea  alba ;  behind,  it  indirectly  corresponds  with  the 
stomach,  which  rests  upon  it  when  the  body  is  placed  in  a  prone  position.! 

*  This  use  of  the  bone  is  eiemplified  in  many  animals  which  are  provided  with  a  sternum,  though  they 
hav«  no  ribs  ;  for  example,  the  frog. 

This  bone  has  attracted  much  of  the  attention  of  the  modem  transcendentalists.  By  them  it  is  regarded  as 
a  vertebral  column  anterior  to  the  intestinal  canal  in  man,  and  inferior  to  it  in  the  lower  animals.  Many  of 
them  have  conceived  that  they  have  found  in  it  a  cervical,  a  dorsal,  and  a  lumbar  regfion,  &c.,  &c. 

M.  Cruveilhier,  in  the  opinion  of  the  editor,  with  much  propriety,  in  the  first  edition  of  his  work,  took  no 
notice  of  the  idle  and  fanciful  speculations  of  the  transcendentalists,  either  in  reference  to  the  sternum,  or  to 
the  analogy  which  exists  between  the  bones  of  the  cranium  and  the  vertebrae.  Although  he  lias,  in  the  sec- 
ond edition,  introduced  some  notices  in  reference  to  the  analogy  which  these  gentlemen  have  attempted  to 
establish  between  the  cranium  and  the  vertebral  column,  believing  that  they  only  increase  the  size  of  the 
book  without  adding  to  its  value,  we  have  excluded  them. — Ed. 

t  In  front  this  appendix  is  sub-cutaneous,  and  the  skin  which  covers  it  is  so  sensible  that  the  slightest  con- 

I 


66  OSTEOLOGY. 

Connexions. — The  sternum  articulates  with  sixteen  bones,  viz.,  fourteen  ribs  through 
the  medium  of  their  cartilages,  and  the  two  clavicles. 

Structure. — It  consists  of  two  very  thin  compact  laminae,  with  an  intervening  spongy 
substance,  the  cells  of  which  are  very  large,  and  have  very  delicate  parietes  ;  it  is  one 
of  the  most  spongy  bones  of  the  body,  and  to  this  circumstance  the  frequency  of  its  dis- 
eases is  doubtless  attributable. 

Development. — The  sternum  is  one  of  the  slowest  bones  in  its  ossification ;  up  tc  the 
sixth  month  of  fcEtal  life,  the  broad  cartilage  of  which  it  is  composed  exhibits  no  bony 
points.  It  is  also,  of  aU  the  bones,  the  one  in  which  the  phenomena  of  ossification  pro- 
ceed with  least  regularity.  For  the  sake  of  simplicity,  we  shall  study  in  succession  the 
development  of  the  three  parts  which  we  have  indicated,  under  the  names  of  manubrium, 
body,  and  xiphoid  appendix. 

1.  Ossification  of  the  Manubrium. — This  part  of  the  bone  sometimes  presents  a  single 
nucleus,  rounded,  and  transversely  oblong ;  sometimes  it  presents  two  nuclei,  and,  in  this 
case,  they  may  be  either  placed  one  above  the  other,  or  side  by  side.  In  the  former 
case,  the  uppermost  nucleus  is  the  larger ;  in  the  latter,  both  may  be  symmetrical  and 
of  equal  size,  or,  what  is  far  more  common,  they  may  be  of  unequal  magnitude.  Lastly, 
the  manubrium  occasionally  presents  more  than  two  osseous  points.  Albinus  found  three 
in  one  subject  and  four  in  another. 

It  should  be  remarked,  that  in  the  case  of  plurality  of  osseous  points,  the  largest  are 
generally  situated  above  :  the  exceptions  to  this  rule  are  very  rare.  The  osseous  points 
make  their  appearance  from  the  fifth  to  the  sixth  month  of  foetal  life. 

2.  Of  the  Body. — The  osseous  nuclei  which  enter  into  the  composition  of  the  body  of 
the  sternum  have  generally  a  rounded  form  when  they  are  single,  and  are  situated  in  the 
median  line ;  when  they  exist  in  pairs,  or  are  placed  laterally,  they  are  more  elongated, 
but  smaller,  and  appear  to  represent  only  the  half  of  one  of  the  single  nodules.  These 
different  osseous  points  are  always  so  arranged  as  to  be  situated  between  two  costo- 
sternal  articulations,  so  that  a  portion  of  the  sternum  is  developed  in  each  of  the  inter- 
vals comprised  between  two  ribs.  The  last  piece  is  the  only  exception,  being  common 
to  the  articulation  of  the  sixth  and  seventh  ribs. 

If  there  be  more  osseous  points  than  one  in  an  intercostal  space,  these,  as  Albinus  has 
remarked,  are  invariably  placed  laterally,  not  one  above  the  other. 

There  are,  therefore,  four  primitive  pieces  in  the  body  of  the  sternum,  and  each  of 
these  is  sometimes  formed  by  one  point  of  ossification ;  at  other  times,  by  two  lateral 
points. 

The  following  is  the  order  in  which  the  ossification  of  the  body  of  the  sternum  pro- 
ceeds :  the  two  upper  pieces  first  appear  from  the  fifth  to  the  sixth  month  of  foetal  life ; 
the  third  is  visible  at  the  sixth  month  ;  the  fourth  most  conunonly  makes  its  appearance 
after  birth,  but  sometimes  towards  the  end  of  gestation. 

In  the  ossification  of  the  body  of  the  sternum,  we  more  frequently  find  examples  of 
two  symmetrical  nodules  placed  on  opposite  sides  of  the  median  line,  than  in  the  develop- 
ment of  the  manubrium,  f^*^ 

Union  of  the  Points  of  Ossification  of  the  Body. — In  cqjteidering  the  union  of  the  differ- 
ent parts  which  compose  the  body  of  the  sternum,  it  i?|i|Mpssary  to  make  a  distinction 
between  the  lateral  conjunction,  that  is,  the  union  of  the  osseous  points  which  are  situated 
on  each  side  of  the  median  line,  and  the  vertical  conjunction,  or  the  union  of  the  pieces  of 
the  sternum  properly  so  called.  The  lateral  conjunction,  or  the  union  of  those  osseous 
germs  which  form  a  pair  in  the  same  interval,  always  precedes  the  vertical  conjunction. 
The  vertical  conjunction,  oj  the  union  of  the  pieces  of  the  body  of  the  sternum  together, 
commences  with  the  two  inferior  portions.  After  this  union,  the  body  of  the  bone  con- 
sists only  of  three  parts.  The  second  piece  then  unites  with  the  lower ;  the  sternal 
foramen  is  found  sometimes  at  the  junction  of  these  last-mentioned  parts,  sometimes  at 
the  place  where  the  two  lateral  points  of  the  fourth  and  of  the  third  portion  of  the  body 
are  united.  The  first  piece  of  the  body  is  not  united  to  the  two  others  until  from  the 
twentieth  to  the  twenty-fifth  year. 

It  should  be  observed,  that  the  union  of  the  divisions  of  the  body  of  the  sternum  takes 
place  precisely  in  the  inverse  order  of  their  appearance.  In  fact,  the  appearance  of  the 
osseous  points  proceeds  from  above  downward,  their  union  from  below  upward  ;  a  fact 
which  verifies  an  assertion  formerly  made,  viz.,  that  the  order  of  development  of  osseous 
points  is  not  always  correlative  to  the  order  of  conjunction. 

3.  Ossification  of  the  Appendix. — This  is  generally  accomplished  by  one  nodule  :  some- 

tusion  produces,  even  in  the  most  powerful  men,  syncope.*  This  fact  may  explain  the  importance  which  has 
been«ttached  to  the  configuration  of  this  process,  and  to  the  names  "pit  of  the  stomach,"  "  scrobiculus  cordis," 
"  pracordittm,"  which  have  been  given  to  the  region  which  corresponds  to  it.  Much  has  been  said  of  the  dis- 
placement of  the  Kiphoid  appendix,  and  of  the  accidents  to  which  this  has  given  place  ;  but,  in  reality,  these 
displacements  hare  never  been  observed,  and  the  accidents  which  have  been  attributed  to  them  have  most  cer- 
tainly depended  on&n  injury  inflicted  on  the  parts  situated  behind  it. 

*  We  do  not  believe  that  the  skin  situated  over  this  appendix  is  more  sensible  than  the  skin  elsewhere. 
The  syncope  which  follows  a  blow  here  is,  in  our  opinion,  produced  by  the  impression  it  produces  on  the  in» 
temal  organs. — Ed. 


THE   RIBS. 


6¥' 


tunes  there  are  two,  and  then  they  are  rarely  symmetrical.  The  process  commences  in 
the  upper  part  of  the  cartilage,  and  very  rarely  extends  through  the  whole.  The  time 
of  appearance  of  the  osseous  point  is  extremely  variable ;  sometimes  it  is  visible  to- 
wards the  third  or  fourth  year ;  sometimes  not  until  the  twelfth,  or  even  the  eigh- 
teenth year. 

In  adult  age,  the  sternum  is  composed  of  the  three  parts  the  development  of  which  I 
have  just  noticed,  and  which  the  ancients  considered  and  described  as  distinct  bones. 
From  the  fortieth  to  the  fiftieth  year,  and  sometimes  later,  the  appendix  becomes  united 
to  the  body,  which  very  rarely  joins  the  manubrium ;  when  such  is  the  case,  the  union 
is  more  apparent  than  real ;  for  if  the  bone  be  cut  verticdly,  the  articulation  is  apparent, 
under  a  very  thin  layer  of  osseous  matter. 

From  what  has  been  said  of  the  numerous  varieties  of  ossification,  it  will  be  evident 
that  it  is  impossible  to  assign  to  this  bone  a  limited  number  of  osseous  points.  To  those 
which  have  been  noticed  I  would  add  two  others,  described  by  Beclard  under  the  name 
of  supra-sternal  points,  which  I  have  seen  once  only  in  the  sternum  of  an  adult,  in  the 
form  of  pisiform  nodules,  placed  on  each  side  of  the  semilunar  notch  of  the  stemiun. 

The  Ribs  (1  to  12,  Jig.  38). 

The  ribs  (^costce,  from  custodes,  as  if,  according  to  the  explanation  of  Monro,  they  were 
the  guardians  of  the  organs  of  the  chest)  ^^^^  3g 

are  osseous  arches  stretched  from  the  ver- 
tebral column  to  the  sternum.  Their  pos- 
terior four  fifths  consist  of  bone  ;  the  ante- 
rior fifth  is  cartilaginous.  The  osseous 
portion  is  the  rib,  properly  so  called ;  the 
cartilaginous  portion  is  named  the  costal 
cartilage. 

The  ribs  are  24  in  number,  12  (1  to  12) 
on  each  side.  Sometimes  there  are  26, 
thirteen  being  on  each  side,  and  then  these 
supernumerary  ribs  are  formed  either  from 
a  part  of  the  transverse  process  of  the  sev- 
enth cervical  vertebra,  or  of  the  transverse 
process  of  the  first  lumbar,  which  affords  an 
evident  proof  of  the  analogy  existing  be- 
tween these  parts.  Sometimes,  but  more 
rarely,  there  are  only  22  ribs,  an  anomaly 
pointed  out  by  Galen.  In  this  case,  we 
sometimes  find  two  adjacent  ribs  united 
throughout  their  entire  length,  sometimes 
the  first  rib  in  a  rudimentary  state,  being 
properly  formed  posteriorly,  but  having  its 
anterior  extremity  lost  in  the>substance  of 
the  scaleni  muscles,  or  united  to  the  second 
rib,  and  through  it  joined  to  the  sternum.* 

The  ribs  are  divided  into  two  classes : 
1.  Those  which  extend  from  the  vertebrae 
to  the  sternum,  the  true  ribs,  sternal  or  ver- 
tebrosternal ribs  (1  to  7).  2.  Those  which 
do  not  reach  the  sternum,  the  false,  aster- 
nal, or  vertebral  ribs  (8  to  12).  The  last  two 
false  ribs  (11  12)  are  called  floating,  because  their  anterior  extremity  is  movable  in  the 
fleshy  parietes  of  the  abdomen.  The  ribs  are  designated  numerically  ;5rs^,  second,  &c., 
counting  from  above  downward.  It  should,  however,  be  observed,  that  in  many  surgi- 
cal works,  the  ribs  are  counted  from  below  upward,  which  is  the  easiest  method  on  the 
living  subject. 

The  ribs  have  certain  general  characters  which  distinguish  them  from  all  other  bones 
and  certain  proper  characters,  by  which  one  is  known  from  another. 

General  Characters  of  the  Ribs. 
The  ribs  resemble  flattened  bony  arches  of  about  six  lines  in  breadth,  and  one  in  thick- 
ness, and  of  lengths  varying  according  to  their  situation.  The  first  rib  is  almost  hori- 
lontal,  and  the  others  in  succession  slope  gradually  more  obliquely  from  behind  forward, 
and  from  above  downward,  their  anterior  extremities  being  on  a  much  lower  plane  than 
the  posterior.  Considered  with  regard  to  their  axes,  i.  e.,  their  absolute  direction,  the 
ribs  represent  portions  of  a  circle  which  successively  increase  to  the  eighth,  and  dimin- 

*  la  a  subject  prepared  for  my  lectures,  the  transverse  processes  of  the  second,  third,  and  fourth  lumbar 
vertebrae  were  elongated,  so  as  to  form  supernumerary  ribs,  while  the  transverse  process  of  the  first  was  un- 
changed. 


09},  OSTEOLOGY. 

ish  again  to  the  twelfth ;  their  curvature  is  not  regular,  the  posterior  part  representing 
the  segment  of  a  much  smaller  circle  than  the  anterior.  They  are  generally  tvnsted  upon 
themselves,  so  that  their  two  extremities  cannot  rest  at  once  upon  the  same  horizontal 
plane.  The  point  where  this  torsion  exists  is  marked  on  the  convex  surface  by  an  ob- 
lique projecting  line,  called  the  angle  (Ji)  of  the  rib ;  but  it  is  not  correct  to  consider  the 
angle  of  the  rib  as  resulting  from  this  torsion ;  it  appears  to  me  simply  intended  for  mus- 
cular insertions. 
The  ribs  have  a  body  and  two  extremities.  The  posterior  or  vertebral  extremity  is 
Fig.  39.  thicker  than  the  rest  of  the  bone,  whence  it  has  received 

the  name  of  head  (i)  {capitulum  casta),  and  presents  two  half 
surfaces  (c  c,  fig.  39),  of  which  the  upper  is  smaller  than  the 
lower,  separated  by  a  horizontal  ridge.  These  two  facettes 
articulate  with  corresponding  surfaces  on  the  bodies  of  the 
dorsal  vertebrae  {d  rf,  fig.  39).  The  head  is  supported  by  a 
constricted  portion,  the  neck  (k,  fig.  38),  which  is  flattened 
from  before  backward,  and  is  the  weakest  part  of  the  bone. 
It  presents  behind  some  inequalities  which  correspond  to  the 
_  transverse  process  of  the  dorsal-  vertebra  below.    Externally 

to  the  neck  is  an  eminence  known  as  the  tubercle  \l  I)  of  the  rib  ;  it  is  divided  into  two 
parts,  which  are  united  at  an  angle,  viz.,  an  internal  and  inferior  portion  {I),  smooth  and 
convex,  which  articulates  with  the  transverse  process  of  the  vertebra  below  the  particu- 
lar rib  examined ;  and  an  external  rough  portion  (Z),  which  gives  attachment  to  liga- 
ments.    The  tubercle  is  in  general  most  prominent  in  the  upper  ribs. 

That  part  of  the  rib  which  is  included  between  the  head  and  the  tubercle  {neck,  cervix) 
is  directed  from  within  outward,  and  slightly  from  above  downward,  so  as  to  reach  the 
summit  of  the  transverse  process  of  the  vertebra  below.  Beyond  the  tubercle,  the  rib 
still  follows  the  same  direction  for  not  more  than  fifteen  lines ;  it  is  then  bent  decidedly 
forward.  The  situation  of  this  curve,  which  corresponds  with  the  torsion  of  the  edges 
above  mentioned,  is  at  the  angle  of  the  rib.  The  interval  which  separates  the  tuberosity 
from  the  angle  is  the  thickest  and  strongest  part  of  the  rib. 

The  rest  of  the  rib  which  is  before  the  angle  becomes  broader  and  thinner,  and  is  di- 
rected forward,  so  that,  as  Haller  expresses  it,  the  line  which  it  describes  represents  in 
some  measure  the  tangent  of  the  posterior  curve.  The  anterior  extremity  (m)  has  a 
hollowed  oval  facette  for  receiving  the  cartilage.  Besides  the  objects  we  have  already 
described,  we  observe,  near  the  anterior  extremity  of  the  rib,  an  oblique  line,  analogous 
to  that  which  forms  the  angle,  but  much  less  marked.  This  line  may  be  considered  as 
forming  the  anterior  angle  of  the  ribs,  and,  like  the  posterior,  it  is  intended  for  muscular 
insertions. 

From  what  has  been  said,  we  perceive  that  the  ribs  present,  1.  A  posterior  extremity 
or  head,  supported  by  a  neck ;  S.  An  anterior  extremity  united  to  the  costal  cartilage ;  3.  A 
body,  having  an  external,  or  cutaneous  surface,  which  is  convex ;  and  an  internal,  or  pul- 
monary surface,  which  is  smooth  and  concave ;  a  superior  edge,  which  is  curved,  thick, 
and  rounded  ;  and  an  inferior  edge,  which  has  a  greater  dujprature  than  the  superior,  is 
thin  and  sharp,  and  marked  by  a  groove  or  furrow  on  the  inner  surface,  called  the  groove 
of  the  ribs  {e,  fig.  39),  which  receives  and  protects  the  intercostal  vessels  and  nerves. 
Lastly,  the  ribs  have  a  double  curvature,  one  of  the  surfaces,  another  of  the  edges ;  this 
last  is  the  curvature  of  torsion. 

Connexions. — The  ribs  are  articulated,  behind,  with  the  dorsal  vertebrae ;  in  front,  with 
the  costal  cartilages. 

Structure. — The  external  aspect  of  a  rib  resembles  a  long  bone ;  but  the  internal  con- 
formation is  analogous  to  that  of  flat  bones.  The  compact  and  spongy  substances  are 
so  distributed  that  these  bones  enjoy  a  certain  degree  of  flexibility,  with  great  power  of 
resistance.  In  young  subjects,  the  compact  substance  is  in  excess ;  in  the  aged,  and  in 
certain  diseases,  the  opposite  is  the  case ;  hence  the  extreme  fragility  of  these  bones, 
which  are  then  broken  by  the  least  effort. 

Development  of  the  Ribs. — The  ribs  are  among  the  earliest  developed  of  the  bones,  the 
'ossification  of  their  bodies  commencing  from  the  fortieth  to  the  fiftieth  day  after  concep- 
tion. They  are  developed  by  three  osseous  points  :  one  primitive,  and  two  epiphysary. 
The  primitive  point  by  itself  forms  the  body  of  the  bone.  Of  the  two  epiphysary  points, 
one  is  intended  to  form  the  hccid  of  the  rib,  the  other  the  tubercle.  They  appear  from 
the  sixteenth  to  the  twentieth  year,  and  they  unite  with  the  rest  of  the  bone  about  the 
twenty-fifth  year.  These  epiphysary  points  do  not  exist  in  the  two  lower  ribs,  which, 
consequently,  have  only  one  point  of  ossification. 

Special  Characters  of  different  Ribs. 
The  differential  characters  of  the  ribs  have  reference,  first,  to  the  length,  which  increas- 
es gradually  from  the  first  to  the  seventh,  and  diminishes  again  to  the  twelfth  ;  secondly, 
to  the  curvature,  the  four  upper  ribs  being  parts  of  much  smaller  circles  than  the  rest, 
and  thus  forming  the  summit  of  the  cone  of  the  chest,  while  the  lower  ribs  constitute  its 


COST'XL    CAST ILAGES.  18^ 

ISase ;  and,  lastly,  to  certain  peculiarities  of  conformation  in  the  first,  second,  third,  elev 
enth,  and  twelfth  ribs,  which  require  special  description. 

The  first  rib  {\,fig.  38,  and^.  40)  is  the  shortest,  and  proportionally  the  broadest  of 
all  the  ribs,  thus  forming  an  imperfect  hd  to  the  bony  case  which  p-    ^q 

constitutes  the  thorax.  Its  edges  are  curved,  but  its  surfaces 
are  flat.  The  curve  which  it  describes  forms  part  of  the  circum- 
ference of  a  much  smaller  circle  than  any  of  the  other  ribs.   The 

posterior  extremity  has  a  small  head  with  a  single  convex  facette  r^M  ^^^k 

(a,  fig.  40),  supported  by  a  long,  thin,  and  cylindrical  neck  (b). 
The  tubercle  (c)  is  very  prominent ;  it  occupies  the  external  bor- 
der, and  gives  an  angular  appearance  to  this  rib.  The  anterior 
extremity  {d)  is  broader  than  that  of  any  other  rib.  Of  the  two  surfaces,  one  is  directed 
upward  and  slightly  outward,  the  other  downward  and  a  little  inward.  The  superioi 
surface  {fi^.  40)  has  two  depressions  separated  by  a  tuberosity  (e).  The  anterior  corre- 
sponds to  the  subclavian  vein  ;  the  posterior  to  the  artery  of  the  same  name.  The  tu- 
berosity which  separates  them  gives  attachment  to  the  anterior  scalenus  muscle.  The 
internal  edge  (a  e  d)  is  concave  ;  the  external  (a  c  d)  is  convex,  and  has  no  groove.  The 
first  rib  has  neither  a  curvature  of  torsion,  nor  an  angle  ;  so  that  the  whole  of  it  can  rest 
upon  the  same  horizontal  plane.  The  superior  surface  presents,  also,  near  its  anterior 
-extremity,  a  depression,  which  appears  to  result  from  pressure  by  the  clavicle,  which  I 
have  seen,  in  some  cases,  immediately  articulated  with  this  bone. 

The  second  rib  (2,  fig-  38)  preser\'es  many  of  the  characters  of  the  preceding,  but  dif- 
fers essentially  in  its  length,  which  is  at  least  double  ;  it  belongs  to  a  much  larger  circle  : 
it  has  no  curvature  of  torsion,  and  can  rest  upon  the  same  plane  with  its  two  ends ;  the 
angle  is  scarcely  visible.  The  external  surface  is  directed  upward ;  it  presents  in  the 
middle  a  very  rough  eminence  for  the  attachment  of  the  serratus  magnus  muscle.  The 
internal  surface  looks  obliquely  downward ;  near  the  tubercle  it  has  a  very  smtill  groove. 

The  third  rib  (3,  fig.  38)  differs  from  the  second  by  its  great  length,  by  the  presence 
of  the  angle,  and  by  a  curvature  of  torsion  sufficient  to  prevent  the  two  ends  from  rest- 
ing at  once  upon  the  same  horizontal  plane. 

The  eleventh  and  twelfth  ribs  (11  l^,fig-  38)  differ  from  all  the  others  by  the  following 
characters:  1.  They  form  segments  of  much  larger  circles  than  any  of  the  others;  2. 
Their  heads  have  only  one  articular  facette,  and  this  is  flattened ;  3.  They  have  no 
neck,  properly  so  called  ;  4.  They  have  no  tubercle  :  5.  They  have  no  groove  ;  6.  They 
have  a  very  thin  and  pointed  anterior  extremity.  These  two  ribs  differ  from  each  other 
only  in  length,  the  twelfth  being  the  shorter. 

The  Costal  Cartilages  (T  to  \1\jig.  38). 
The  flexibility  and  elasticity  of  the  ribs  is  partly  owing  to  their  structure,  but  more 
'  especially  to  the  costal  cartilages  which  prolong  them  in  front.  There  are  twelve  cos- 
tal cartilages,  distinguished  niunerically  as  first,  second,  third,  &c. ;  they  are  separated 
from  each  other  by  intervals,  which  are  very  considerable  at  the  upper  part  of  the  tho- 
rax, but  gradually  diminish  as  we  proceed  downward :  it  is  not  very  uncommon  to  meet 
with  thirteen  cartilages  on  one  side ;  at  other  times  there  are  only  eleven.  We  some- 
times find  two  cartilages  which  are  joined  together,  and  articulated  with  the  sides  of 
the  sternum ;  when  there  are  thirteen  cartilages,  the  supernumerary  one  generally  exists 
between  the  third  and  fourth  ribs  ;  it  is  thin,  and,  as  it  were,  rudimentary ;  it  does  not 
form  the  continuation  of  any  rib,  and  terminates  insensibly  in  the  muscles.  The  first 
seven  cartilages  (1  to  7)  articulate  immediately  with  the  sternum ;  and  hence  the  name 
of  sternal  given  to  the  ribs  with  which  they  are  connected.  Of  the  other  five  cartilages, 
the  last  two  (11  12)  have  no  connexion  with  those  that  precede  them;  and,  from  this 
circumstance,  the  navae  floating  has  been  given  to  the  last  two  ribs. 

General  Characters  of  the  Costal  Cartilages. 
All  the  costal  cartilages  are  flattened  like  the  ribs,  and  precisely  resemble,  in  breadth 
and  thickness,  the  bones  to  which  they  are  attached.  The  external  end  is  received  into 
a  cavity  hollowed  out  in  the  anterior  extremity  of  the  rib  :  their  internal  or  sternal  ex- 
tremity, which  is  much  narrower  than  the  external,  is  angular,  and  articulates  with  the 
corresponding  angular  facettes  of  the  sternum.  Their  anterior  or  cutaneous  surfaces 
are  slightly  convex,  and  covered  by  the  muscles  of  the  anterior  region  of  the  trunk,  to 
many  of  which  they  give  attachment.  Their  posterior  or  mediastinal  surfaces  are 
slightly  concave.  Their  superior  and  inferior  edges  bound  the  intercostal  spaces,  and 
give  attachment  to  the  muscles  of  the  same  name.  They  are  altogether  distinct  from 
articular  cartilages,  and  have  a  peculiar  tendency  to  ossify,  this  process  taking  place 
partly  on  the  surface,  and  partly  from  within  outward. 

Differential  Characters  of  the  Costal  Cartilages. 
The  costal  cartilages  increase  in  length  from  the  first  to  the  seventh,  and  sometimes 
to  the  eighth,  which  in  this  case  articulates  with  the  sternum ;  they  diminish  in  length 


70  OSTEOLOGY. 

from  the  seventh  to  the  twelfth.  This  difference  depends  on  the  circumstance  that  the 
osseous  parts  of  the  upper  ribs  terminate  anteriorly  in  a  line  directed  obhquely  from 
above  downward,  and  from  within  outward,  and  that  the  sternum  is  only  about  half  the 
length  of  the  lateral  wall  of  the  thorax,  so  that  only  the  first  four  or  five  cartilages  could 
join  this  bone,  did  not  the  others  bend  upward,  so  as  to  reach  its  sides  or  join  the  lower 
edge  of  the  cartilage  above  ;  the  first  three  cartilages  alone,  therefore,  follow  the  same 
direction  as  the  bony  rib.  The  first  cartilage  differs  from  all  the  others  by  its  shortness, 
its  thickness  and  breadth,  and  its  tendency  to  ossify ;  it  is  ahnost  always  bony  in  the 
■  adult ;  it  is  often  continuous  with  the  sternum,  but  is  sometimes  only  contiguous,  in 
which  case  its  articulation  to  this  bone  presents  a  great  difference  as  respects  motion. 
The  second  and  third  costal  cartilages  cannot  be  distinguished  from  each  other,  but  they 
differ  from  the  rest  in  being  joined  at  right  angles  with  the  sternum,  in  not  being  bent, 
and  in  being  as  broad  at  their  sternal  as  at  their  costal  extremities.  The  fourth  carti- 
lage becomes  bent  upward,  after  having  followed  the  direction  of  the  rib  for  a  little  way. 
The  length  and  curvature  of  the  cartilages  of  the  fifth,  sixth,  and  seventh  ribs  progres- 
sively increase  :  the  seventh  is  at  least  three  inches  long,  whUe  the  fifth  is  not  more 
than  thirteen  or  fourteen  hues ;  their  inner  ends  become  successively  narrowed,  so  as 
to  correspond  with  the  diminishing  cavities  on  the  edges  of  the  sternum ;  the  borders 
of  the  fifth,  sixth,  seventh,  and  eighth  costal  cartilages  articulate  together,  and  present, 
for  this  purpose,  articular  facettes,  supported  by  eminences.  The  cartilages  of  the 
eighth,  ninth,  and  tenth  ribs  gradually  diminish  in  length ;  externally  they  have  the  same 
breadth  as  the  rib,  and  decrease  as  they  pass  inward,  so  as  to  terminate  by  a  pointed 
extremity,  which  is  applied  to  the  lower  edge  of  the  rib  above.  The  cartilages  of  the 
eleventh  and  twelfth  ribs  are  extremely  short,  especiaUy  that  of  the  twelfth,  which  is 
only  a  few  lines  in  length ;  their  internal  free  extremity  loses  itself,  so  to  speak,  in  the 
substance  of  the  abdominal  parietes,  so  that  they  are  altogether  unconnected  with  the 
other  cartilages. 

The  Thorax  in  genekal. 

The  sternum,  the  ribs,  and  the  whole  dorsal  region  of  the  vertebral  column,  form  the 
framework  of  a  large  visceral  cavity,  the  thorax,  intended  to  contain  and  protect  the 
chief  organs  of  respiration  and  circulation.  It  occupies  the  upper  part  of  the  trunk,  be- 
tween the  thoracic  extremities ;  its  boundaries  are  very  well  defined  above,  but  below 
there  is  not  any  line  of  demarcation  in  the  skeleton  between  the  cavities  of  the  thorax 
and  abdomen ;  or,  rather,  the  bony  thorax  is  common  to  the  thoracic  and  abdominal  vis- 
cera. We  shall  see  afterward,  that  these  two  cavities  are  separated  from  each  other 
by  a  movable  and  muscular  septum  called  the  diaphragm. 

With  regard  to  capacity,  the  thorax  holds  a  middle  place  between  the  cavity  of  the 
cranium  and  that  of  the  abdomen.  In  each  individual,  the  capacity  of  the  thor2ix  is  ex- 
actly proportional  to  the  volume  of  the  lungs  ;  and  as,  in  general,  voluminous  lungs  co- 
exist with  a  highly-developed  muscular  apparatus,  it  follows  that  the  size  of  the  thorax 
is  no  equivocal  sign  of  a  vigorous  constitution.  The  thorax  differs  much  from  the  ab- 
dominal cavity  in  regard  to  its  extensibility,  being  only  capable  of  very  Umited  alternate 
movements  of  dilatation  and  contraction.  In  the  structure  of  the  thorax,  we  find  the 
twofold  condition  of  solidity  and  mobility  in  so  perfect  a  degree,,  that  the  framework  of 
which  it  is  composed  is  equally  fitted  to  serve  as  a  protecting  structure  and  a  respira- 
tory apparatus.  This  limited  dilatabihty  contrasts,  on  the  one  hand,  with  the  almost  in- 
definite extensibility  of  the  abdominal  cavity,  and,  on  the  other,  with  the  absolute  want 
of  extensibility  in  the  cranium. 

We  should  form  a  very  incorrect  idea  of  the  dimensions  and  shape  of  the  thorax,  if 
we  were  to  judge  of  them  by  its  external  aspect  while  still  covered  by  the  soft  parts, 
and  surrounded  by  that  species  of  girdle  which  is  formed  by  the  shoulder  round  its  upper 
part ;  for  we  should  then  conclude  it  to  be  a  truncated  cone,  with  the  base  above.  On 
the  contrary,  when  the  surrounding  parts  are  removed,  the  thorax  represents  a  cone, 
the  base  of  which  is  in  precisely  the  opposite  direction,  that  is,  below.  The  height  of 
Ihe  thorax  cannot  be  measured  with  exactness,  because  it  varies  according  to  the  de- 
pression or  elevation  of  the  muscular  septum,  which  intervenes  between  the  thoracic 
and  the  abdominal  cavities.  We  can  only  say,  that  the  bony  framework  should  be  di- 
vided into  two  parts,  a  superior  or  supra-diaphragmatic,  which  belongs  to  the  chest,  prop- 
erly so  called,  and  contains  the  lungs  and  heart ;  and  an  inferior,  which  forms  part  of 
the  cavity  of  the  abdomen,  and  contains  the  liver,  the  spleen,  the  kidneys,  the  stomach, 
the  duodenum,  and  part  of  the  colon.  It  should  be  also  remarked,  that  the  supra  and 
sub-diaphragmatic  portions  of  the  thorax  constantly  vary  in  their  respective  proportions ; 
and  that  these  variations  of  height  principally  take  place  at  the  sides,  the  middle  remain- 
ing always  nearly  the  same.  The  transverse  diameters  increase  rapidly  from  the  upper 
to  the  lower  part  of  the  thorax.  The  same  is  true  of  the  antero-posterior  diameters,  and 
these  also  sensibly  increase  opposite  the  concavity  of  the  dorsal  region  of  the  spine. 
The  antero-posterior  diameters  are  much  greater  laterally  than  in  the  median  line, 
where  they  are  diminished  by  the  considerable  projection  of  the  bodies  of  the  dorsal  ver- 


THE  THORAX   IN  GENERAL.  71 

tebrae.  This  shortness  of  the  antero-posterior  diameters  between  the  sternum  and  the 
vertebral  column  is  in  proportion  to  the  small  size  of  the  heart,  which  is  situated  in 
this  region,  as  compared  with  that  of  the  lungs,  which  occupy  the  sides. 

Antero-posterior  Flattening. — The  cone  represented  by  the  thorax  is  flattened  from  be- 
fore backward.  This  flattening  appears  to  be  connected  with  the  existence  of  the  clav- 
icle, for  we  meet  with  it  in  all  animals  provided  with  this  bone,  while  in  those  in  which 
it  does  not  exist  the  flattening  is  lateral,  i.  e.,  from  one  side  to  the  other. 

The  shape  of  the  thorax  is  subject  to  many  varieties,  as  respects  different  individuals, 
age,  sex,  &c.  Of  the  individual  varieties,  some  are  compatible  with  health,  others  are 
pathological,  and  constitute  malformations,  the  history  of  which  belongs  to  the  subject 
of  diseases  of  the  chest.  Sometimes  they  are  congenital ;  at  other  times  they  are  the 
result  of  accidental  circumstances  which  have  modified  the  primitive  conformation. 

In  some  subjects  the  lateral  exceeds  the  antero-posterior  flattening,  and  the  sternum 
is  prominent,  as  we  habitually  see  it  in  the  thorax  of  phthisical  patients. 

Many  individual  varieties  of  conformation  of  the  thorax  are  the  effect  of  frequently 
repeated,  or  permanent  compressions  exercised  on  the  bony  cavity.  I  have  seen  infants 
in  whom  the  thorax  was  perfectly  well  formed  at  birth,  but  had  been  deformed  and  flat- 
tened on  the  sides  by  pressure  from  the  hands  of  the  nurse.  If  there  be,  in  fact,  a  time 
when  the  slightest  external  pressure  may  be  productive  of  permanent  deformity,  it  is 
during  the  first  years  of  life.  The  effects  of  a  strong  and  permanent  constriction  are 
also  manifest  in  a  very  evident  manner,  in  the  alterations  of  the  form  of  the  thorax  con- 
sequent upon  the  use  of  stays.  This  species  of  constriction  affects  principally  the  lower 
part  of  the  chest ;  so  that  the  fifth,  sixth,  seventh,  eighth,  ninth,  and  tenth  ribs  are  press- 
ed forward  and  inward,  because  the  length  and  flexibility  of  their  cartilages  allow  them 
to  yield  readily ;  and  all  the  viscera  which  correspond  to  this  species  of  girdle  undergo 
very  marked  alterations  in  their  direction,  and  even  in  their  figure  and  position.  Thus 
the  liver,  the  spleen,  and  the  stomach  are  forced  upward  and  compress  the  lungs,  which, 
in  their  turn,  are  pushed  to  the  upper  part  of  the  chest,  and  have  a  tendency  to  pass  con- 
siderably beyond  the  level  of  the  first  rib  ;  2.  The  stomach  becomes  more  oblique ;  3. 
The  transverse  arch  of  the  colon  is  often  forced  downward  ;  the  pregnant  uterus  acquires 
an  oblique  direction.  In  an  old  female,  whose  thorax  was  so  contracted  below  as  to 
present  the  appearance  of  a  barrel,  and  bore  witness  to  the  use  of  a  very  tight  corset, 
the  cartilage  of  the  seventh  rib,  on  the  right  side,  was  in  contact  with  that  of  the  oppo- 
site rib  ;  the  xiphoid  appendix  was  strongly  depressed,  and  pushed  behind  the  cartilages 
of  the  seventh  and  eighth  ribs,  which  touched  each  otlier.  Some  varieties  of  conforma- 
tion depend  upon  deviations  of  the  vertebral  column  ;  they  evidently  belong  to  patholo- 
gic2il  anatomy,  and  need  not  occupy  our  attention.  In  the  female,  the  chest  resembles 
a  cone,  with  a  larger  base,  but  of  less  height  than  in  the  male. 

There  are  certain  varieties  at  different  ages,  which  will  be  noticed  in  the  history  of 
the  general  development  of  the  thorax. 

As  the  thorax  does  not  form  a  regular  cone,  when  we  speak  of  its  axis  being  directed 
obhquely  from  above  downward,  and  from  behind  forward,  we  only  refer  to  its  anterior 
wall,  the  posterior  and  latereil  being  altogether  devoid  of  this  obliquity. 

We  shall  now  consider  in  detail  the  external  and  the  internal  surface  of  the  thorax ; 
the  inferior  circumference  or  base,  and  the  superior  circumference  or  summit,  resulting 
from  its  conical  form. 

External  Surface  of  the  Thorax. 

On  this  surface  we  find  an  anterior,  a  posterior,  and  two  lateral  regions. 

The  anterior  or  sternal  region,  much  wider  below  than  above,  forms  a  plane  inclined 
from  above  downward,  and  from  behind  forward,  and  more  or  less  projecting  according 
to  the  general  conformation  of  the  thorax.  It  presents,  1.  In  the  middle,  the  cutaneous 
surface  of  the  sternum;  2.  On  the  sides,  the  series  of  articulations  of  the  cartilages  of 
the  ribs  with  the  sternum ;  3.  The  costal  cartilages,  those  being  the  longest  which  ap- 
pertain to  the  lower  ribs  ;  4.  Between  the  cartilages,  certain  intervals  named  intercostal 
spaces ;  5.  Externally  to  the  cartilages,  an  oblique  line  running  from  above  downward, 
and  from  within  outward,  and  marking  the  series  of  articulations  of  the  costal  cartilages 
with  the  ribs  ;  6.  Still  more  externally,  another  oblique  line,  wliich  has  not  been  pointed 
out,  and  which  is  formed  by  the  anterior  angles  of  the  ribs  ;  it  corresponds  in  obhquity 
with  the  chondro-stemal  Hne,  and  forms  the  boundary  of  the  anterior  region. 

The  posterior  or  vertebral  region  presents,  in  the  median  line,  the  series  of  dorsal  spi- 
nous processes  ;  on  the  sides,  1.  The  vertebral  grooves  ;  2.  The  series  of  dorsal  trans- 
verse processes ;  3.  Their  articulation  with  the  tubercles  of  the  ribs  ;  4.  A  series  of 
surfaces,  of  which  the  lower  are  the  largest,  and  which  are  comprised  between  the  angle 
and  the  tubercle  of  each  rib  ;  5.  Lastly,  an  oblique  line,  running  from  above  downward, 
and  from  within  outward,  formed  by  the  posterior  angles  of  the  ribs. 

The  lateral  or  costal  regions  resemble  a  sort  of  curved  grate,  more  convex  behind  than 
in  front,  and  showing  the  series  of  ribs  and  intercostal  spaces  in  the  same  manner  as 
the  anterior  and  posterior  regions.     They  increase  in  width  from  above  downward,  and 


72  OSTEOLOGY, 

form  a  sort  of  inclined  plane,  with  a  curved  surface,  and  obliquely  directed  from  above 
downvi^ard,  and  from  within  outward.  The  first  two  intercostal  spaces  are  both  the 
broadest  and  the  shortest ;  the  third  and  fourth  are  broader  in  front  than  behind ;  the 
following  are  of  almost  uniform  width  through  their  whole  extent :  on  the  whole,  tue 
breadth  of  the  spaces  diminishes  from  above  downward,  or,  as  Bertin  remarks,  tlie  edge? 
of  the  lower  ribs  are  almost  in  contact.  The  last  two  intercostal  spaces  form  the  onlj 
exception,  for  they  are  nine  lines  in  width,  while  those  in  the  middle  of  the  chest  are 
only  about  four.  It  should,  moreover,  be  remarked,  that  the  intercostal  spaces  are 
broader  in  front  than  behind ;  a  fact  which  may  be  easily  shown  by  comparing  the  dis-  . 
tance  which  separates  the  anterior  extremities  of  the  first  and  second  ribs  with  that 
which  intervenes  between  their  posterior  terminations.  The  length  of  the  intercostal 
spaces  increases  from  the  first  to  the  sixth ;  it  then  diminishes  to  the  last  two,  where  it 
is  very  small. 

Internal  Surface  of  the  Thorax. 

This  surface,  like  the  external,  is  divided  into  four  regions.  The  anterior  region  ex- 
actly resembles  the  anterior  region  of  the  external  surface,  with  this  difference  only, 
that  it  is  concave  instead  of  being  convex. 

•  The  -posterior  region  presents,  1.  In  the  median  line,  the  dorsal  portion  of  the  spinal 
coliuntm,  which,  like  an  incomplete  septum,  forms  a  projection  in  the  interior  of  the  tho- 
racic cavity,  and  divides  it  into  two  equal  parts ;  2.  On  the  sides,  two  deep  grooves, 
which  are  contracted  above,  but  gradually  enlarge  towards  the  lower  part.  These 
grooves,  which  lodge  the  posterior  convex  portions  of  the  lungs,  exist  only  in  the  human 
subject ;  they  allow  part  of  the  weight  of  the  body  to  be  throwTi  backward — an  arrange- 
ment which  is  very  advantageous  for  preserving  the  equilibrium  in  standing,  and  is  a 
proof  that  man  is  destined  to  the  erect  posture. 

The  lateral  regions  form  an  inclined  plane  on  the  inside,  resembling  that  which  exists 
on  the  outside,  only  they  are  concave  instead  of  being  convex. 

Superior  and  Inferior  Circumferences. 

The  superior  circumference  or  summit  is  narrow  in  comparison  with  the  inferior,  and 
slopes  obliquely  from  above  downward  and  forward ;  it  is  wider  transversely  than  in 
the  antero-posterior  direction,  and  resembles  the  shape  of  a  heart  on  playing  cards.  The 
circumference  of  this  opening  is  formed,  in  front,  by  the  upper  end  of  the  sternum ;  be- 
hind, by  the  first  dorsal  vertebra ;  on  the  sides,  by  the  first  ribs  and  their  cartilages. 
This  opening,  which  is  contracted  in  its  dimensions  by  the  clavicles,  gives  passage  to 
the  following  organs :  the  trachea,  the  oesophagus,  the  thoracic  duct,  the  large  arteries 
and  veins  of  the  head,  neck,  and  thoracic  extremities,  the  apex  of  the  lungs,  and  several 
muscles  of  the  neck. 

The  inferior  circumference  or  hase  is  very  wide,  at  least  four  times  larger  than  the  pre- 
ceding, and,  like  it,  broader  transversely  than  from  before  backward.  It  presents,  1.  In 
front,  a  wide  notch,  the  borders  of  which  are  formed  by  the  cartilages  of  the  seventh, 
eighth,  ninth,  and  tenth  ribs,  but  are  incomplete  between  the  tenth  and  eleventh,  as  also 
between  the  eleventh  and  twelfth ;  at  the  apex  of  this  notch  is  the  ensiform  cartilage. 
2.  Behind,  we  find  on  each  side  of  the  vertebral  column  a  notch  of  much  smaller  dinien- 
sions  than  that  in  front ;  it  is  caused  by  the  great  obliquity  of  the  twelfth  rib,  which 
forms  an  acute  angle  with  the  spine.  The  inferior  circumference  of  the  thorax  is  con- 
nected with  muscles  by  numerous  attachments. 

The  great  mobility  enjoyed  by  the  lower  aperture  of  the  thorax,  which,  as  we  have  seen, 
is  subjected  to  alternate  movements  of  dilatation  and  contraction,  contrasts  remarkably 
with  the  almost  absolute  immutability  of  the  superior  aperture.  The  lower  opening  pre- 
sents certain  varieties  in  dimension  which  are  observed  chiefly  during  inspiration,  or  are 
occasioned  by  accidental  causes  of  dilatation,  such  as  pregnancy  or  the  accumulation  of 
fluids  in  the  abdominal  cavity.  This  variability  of  its  dimensions  has  reference  to  the 
compressibility  and  dilatability  of  the  abdominal  viscera.  Such  an  alteration  at  the  upper 
opening  would  have  caused  serious  inconvenience  by  compressing  the  trachea  and  the 
vessels. 

General  Development  of  the  Thorax. 

The  shape  and  dimensions  of  the  thorax  vary  considerably  at  different  periods  of  Ufe ; 
it  is  of  great  importance  to  be  well  acquainted  with  these,  because  they  bear  constant 
relation  to  changes  in  the  organs  contained  within  the  cavity. 

One  of  the  most  remarkable  characteristics  of  the  fcetal  thorax  is  the  predominance  of 
the  antero-posterior  over  the  transverse  diameter  ;  at  this  age  we  find  the  sternum  very 
far  separated  from  the  spine,  and  forming  a  considerable  projection  in  front.  This  ar- 
rangement coincides  with  the  largely-developed  state  of  the  heart,  and  an  organ  denom- 
inated the  thymus  gland,  which  are  both  situated  in  the  middle  of  the  thorax ;  and  also 
with  the  small  size  of  the  lungs,  which  are  situated  laterally.  Another  marked  feature 
in  the  chest  of  the  foetus  is  the  absence,  or,  at  least,  the  slight  depth,  of  those  grooves 
which  we  have  described  as  peculiar  to  man,  and  intended  to  lodge  the  posterior  edge  of 


THE    LIMBS.  73 

the  lungs.  The  absence  of  these  pulmonary  grooves  produces,  as  a  necessary  conse- 
quence, a  want  of  those  external  projections  on  the  back  of  the  thorax,  which  we  find  in 
the  adult  corresponding  with  the  grooves  on  the  interior.  These  two  characteristics, 
viz.,  the  predominance  of  the  antero-posterior  diameter,  and  the  absence  of  the  grooves, 
both  depend  on  the  same  cause,  viz.,  the  shght  degree  of  curvature  of  the  ribs  in  the  foetus. 

At  a  more  advanced  period  the  curvatures  increase,  the  posterior  grooves  are  gradu- 
ally developed,  the  antero-posterior  diameter  is  diminished,  and  the  transverse  propor- 
tionally increased,  so  that  there  is  less  difference  in  the  absolute  capacity  of  the  thorax 
than  would  at  first  sight  appear,  for  the  differences  we  have  noticed  are  in  a  great  measure 
referrible  to  the  comparative  predominance  of  one  or  other  diameter.  We  should  also 
remark,  that  in  the  foetus,  the  vertical  diameter,  particularly  at  the  sides,  is  much  shorter^ 
on  account  of  the  unexpanded  state  of  the  lungs,  and  the  elevation  of  the  diaphragm  by 
the  abdomind  viscera. 

The  two  circumferences  likewise  present  remarkable  differences.  In  the  foetus,  the 
superior  opening  has  a  greater  extent  from  before  backward  than  transversely,  which  is 
precisely  the  opposite  of  what  is  observed  in  the  adult.  The  inferior  aperture  is  ex- 
tremely wide  in  every  direction ;  and  this  accords  with  the  large  size  of  many  of  the 
abdominal  viscera  at  this  age,  and  particularly  of  the  Uver. 

At  birth  there  is  a  sudden  enlargement  of  the  chest,  because  the  access  of  air  increases 
the  lungs  to  a  double  or  threefold  extent,  which,  up  to  this  period,  were  much  contract- 
ed. At  puberty,  the  thorax  participates  in  the  great  development  which  the  respiratory 
apparatus  undergoes.  It  is  at  this  time,  eiIso,  that  malformations  of  this  cavity  most  fre- 
quently become  obvious.  In  adult  age,  the  thorax  still  grows,  but  in  an  sdmost  insen- 
sible manner. 

In  the  aged,  the  different  pieces  of  the  sternum  become  united  by  osseous  union :  the 
cartilages  are  ossified ;  the  thorax  has  a  tendency,  in  some  degree,  to  form  only  one 
piece,  which  does  not  permit  the  different  parts  to  move  upon  one  another. 


THE  LIMBS. 

The  vertebral  column  alone,  in  many  animals,  is  the  organ  of  locomotion,  and  the  jaws 
the  organ  of  prehension  ;  but  all  animals  so  constituted  either  live  in  water  or  crawl  on 
the  earth.  The  vertebral  column,  however,  in  man,  and  in  those  animals  which  live  in 
the  air,  is  not  constructed  in  such  a  way  as  to  allow  of  the  performance  of  a  complete 
locomotion,  and  thence  the  necessity  of  limbs,  which  are  only  connected  to  the  trunk  by 
their  superior  extremities,  and  which,  along  the  rest  of  their  length,  are  completely  iso- 
lated from  the  body.  They  are  also  denominated  extremities,  because  they  are  the  parts 
which  are  most  distant  from  the  centre  of  the  body.  They  are  four  in  number :  two  supe- 
rior, or  thoracic,  so  called  because  they  are  directly  connected  with  the  thorax ;  and  two  in- 
ferior, or  abdominal,  because  they  are  continuous  with  the  abdominal  cavity.  These  last 
are  intended  to  support  the  weight  of  the  body  like  two  pillars,  and  to  transport  it  from 
place  to  place  :  the  thoracic  hmbs  are  intended  to  seize  objects  or  to  repel  them.  The 
extremities  present  in  their  structure  certain  general  circumstances  which  are  essen- 
tially characteristic.    We  shaU  particularly  notice  the  following : 

1.  As  regards  their  form.  The  bones  of  the  extremities  differ  in  many  respects  both 
from  those  of  the  trunk  and  those  of  the  head.  They  generally  have  the  appearance  of 
cylindrical  and  elongated  levers,  superimposed  so  as  to  form  a  column,  the  parts  of 
which  are  movable  upon  each  other. 

2.  The  continuity  of  the  extremities  with  the  trunk  is  established  by  means  of  osseous 
zones  or  girdles,  viz.,  the  shoulder  for  the  thoracic  limbs,  the  pelvis  for  the  abdominal. 

3.  The  bones  of  the  extremities  diminish  in  size  and  length  from  the  proximal  to  the 
distal,  or  free  end. 

4.  The  nimiber  of  the  bones  in  the  limbs  augments  as  we  proceed  towards  their  free 
extremity. 

5.  As  a  necessary  consequence  of  the  augmented  number  of  bones,  and  of  their  pro- 
gressively diminished  size,  the  articulations  become  more  numerous  and  smaller  towards 
the  distal  end  of  the  limb. 

The  thoracic  and  abdominal  extremities  being  constructed  upon  the  same  fundamental 
type,  we  should  never  forget,  in  describing  them,  that  they  have  numerous  analogies, 
while,  at  the  same  time,  we  notice  the  differences  in  each  which  are  connected  with  its 
peculiar  ofiice. 

THE  SUPERIOR  OR  THORACIC  EXTREMITIES. 

The  Shoulder. — Clavicle. — Scapula. — The  Shoulder  in  general. — Development. — Humerm. 

— Ulna. — Radius. — The  Hand. — The  Carpus  and  Carpal  Bones. — The  Metacarpus  an4 

Metacarpal  Bones. — The  Fingers. — General  Development  of  the  Superior  Extremities. 

;,  The  thoracic  extremities  arQ  divided  into  four  parts,  which,  proceeding  from  the  central 

Dwards  the  distal  end,  are,  1.  The  shoulder ;  2.  The  arm  ;  3.  The  fore-ann ;  4.  The  hand 

K 


'i4  OSTEOLOGY. 

■;„*?r":t  The  Shoulder.  ^mfiX-     •  ^^  .,»  ..J  ;..' 

The  shoulder,  situated  at  the  posterior  and  lateral  part  of  the  chest,  is  composed  of 
two  bones,  which  form  by  their  union  a  sort  of  angular  lever  with  a  horizontal  and  a  ver- 
<ical  arm.    The  horizontal  arm  is  represented  by  the  clavicle ;  the  vertical,  by  the  scapula. 

The  Clavicle  {fig.  41). 

The  clavicle  performs  so  important  an  office  in  the  mechanism  of  the  thoracic  extrem- 
Fig.M.  ity,  that,  upon  its  presence  in  a  certain  number  of  an- 

imals, and  its  absence  in  others,  the  extremely  im- 
portant distinction  between  claviculated  and  non-cla- 
viculated  animals  has  been  founded. 

The  clavicle,  so  called  from  its  supposed  resem- 
blance  to  a  key,  occupies  the  superior  and  anterior  part  of  the  thorax,  and  forms  the  an- 
terior portion  of  the  shoulder.  It  is  placed  horizontally  between  the  sternum,  which  is 
its  fulcrum,  and  the  scapula,  the  movements  of  which  it  follows.  Its  length  varies  in 
different  individuals,  and  more  particularly  in  the  different  sexes ;  in  the  female  it  is 
generally  longer  than  in  the  male.  It  is  a  long  bone,  and  forms  one  of  a  pair,  and  is 
consequently  asymmetrical ;  its  inner  end  (,e,fig.  41),  which  is  the  larger,  is  rounded ; 
its  outer  end  (d)  is  flattened  from  above  downward,  and  it  enlarges  progressively  from 
without  inward  like  a  cone.  Its  direction  should  be  carefully  studied.  Proceeding 
from  its  outer  end,  which  is  very  thin,  we  find  it  describing  a  curve  with  the  concavity 
forward  (d  a) ;  it  then  changes  its  direction,  and  describes  a  much  larger  curve  with  the 
concavity  looking  backward  {a  c).  The  clavicle,  therefore,  has  two  alternate  curvatures, 
resembling  an  italic  S,  an  arrangement  which  has  the  advantage  of  giving  strength  to 
the  bone,  since  each  curve  becomes  the  seat  of  a  decomposition  of  forces,  which  greatly 
diminishes  the  violence  of  shocks  directed  against  it  from  without  inward. 

The  clavicle  may  be  divided  into  a  body  and  extremities. 

The  body  (a)  presents  two  surfaces,  one  superior  and  one  inferior ;  and  two  borders, 
an  anterior  and  a  posterior. 

The  superior  surface  (a)  of  the  body  is  placed  almost  immediately  under  the  skin,  and 
offers  an  extensive  and  ill-protected  surface  to  the  action  of  foreign  bodies  ;  this  is  one 
of  the  causes  of  the  great  frequency  of  fractures  of  this  bone.  This  surface  is  covered 
by  the  skin,  the  platysma  myoides  muscle,  and  numerous  filaments  of  the  cervical  plexus 
of  nerves.*  Hence,  direct  blows  upon  the  clavicle  are  accompanied  with  severe  pain, 
on  account  of  the  compression  of  the  nerves  of  this  plexus.  We  find  on  this  surface, 
near  its  inner  end,  a  tubercle  for  the  insertion  of  the  sterno-mastoid  muscle  ;  it  has  also 
some  inequalities  for  muscular  attachments  on  the  outside. 

The  inferior  surface,  broad  externally,  and  narrow  internally,  like  the  preceding,  is 
marked  by  a  groove,  running  longitudinally,  and  lodges  the  subclavian  muscle.  Near  the 
inner  extremity  of  this  surface  there  is  sometimes  a  facette,  which  articulates  with  the 
first  rib,  and,  on  its  inferior  surface,  inequalities  for  the  insertion  of  the  costo-clavicular 
ligament.  Near  the  outer  end  there  is  a  very  rough  tuberosity,  and  an  irregular  hne, 
directed  obliquely  from  within  outward  and  from  behind  forward  :  they  are  both  intended 
for  the  insertion  of  strong  ligaments  which  unite  the  clavicle  and  the  scapula,  the  coraco- 
clavicular  ligaments.  The  internal  third  of  this  surface  corresponds  to  the  first  rib, 
which  it  embraces  and  crosses  at  a  very  acute  angle.  The  middle  third  corresponds  to 
the  first  intercostal  space,  from  which  it  is  separated  by  the  brachial  plexus  and  the  ax- 
illary vessels  ;  the  external  third  is  in  relation  to  the  coracoid  process  and  the  articula- 
tion of  the  shoulder  with  the  arm. 

The  anterior  border  (b),  which  is  thin  externally,  becomes  expanded  into  a  surface  to- 
wards the  inner  end ;  its  external  third  is  concave,  the  two  internal  thirds  are  convex. 
This  convexity  dlows  the  clavicle  to  resist,  like  an  arch,  any  violence  applied  directly 
from  before  backward.  The  external  third  of  this  border,  where  it  gives  insertion  to 
the  deltoid  muscle,  is  rough,  but  the  two  internal  thirds  are  less  uneven. 

The  posterior  border  (c)  is  concave  in  its  four  inner  fifths,  and  convex  and  rough  in  its 
external  fifth,  for  the  insertion  of  the  Trapezius  muscle.  Its  relations  are  very  impor- 
tant ;  the  subclavian  vein  runs  along  it,  and  it  also  corresponds  to  the  subclavian  artery 
and  the  brachial  plexus.  From  this  it  may  be  conceived  how  dangerous  fractures  of 
the  clavicle  might  become,  if  the  sharp  end  of  the  fragments  should  penetrate  among 
the  nerves  or  the  vessels ;  it  may  also  be  imagined  how  depression  of  the  clavicle,  by 
compressing  the  vessels  which  are  distributed  to  the  upper  extremity,  may  suspend  the 
circulation  there  ;  and,  lastly,  we  can  understand  how  it  is  easy  to  apply  a  hgature  to 
the  subclavian  artery,  by  cutting  along  the  middle  of  the  clavicle.  There  still  remains 
one  important  relation  to  be  noticed,  viz.,  the  propinquity  of  the  apex  of  the  lungs,  from 
which  circumstance  it  becomes  possible  to  ascertain  the  sonorousness  of  this  portion  of 
the  lungs  by  percussion  on  the  clavicle. 

Extremities. — The  external  or  acromial  end  (d)  of  the  clavicle  is  thin,  and  flattened  from 
*  It  is  uot  uncommon  to  find  the  body  of  the  clavicle  itself  traversed  by  a  nerve  of  the  cervical  plexus. 


THE   SCAPULA. 

ire  downward ;  it  presents  a  very  narrow  elliptical  facette,  whicli  looks  downward 
and  outward,  and  articulates  with  a  corresponding  surface  on  the  scapula.  This  is  the 
weakest  part  of  the  bone  ;  it  lies  almost  immediately  below  the  skin,  and  is  much  expo- 
sed to  external  violence,  by  which  it  is  sometimes  broken. 

The  internal  or  sternal  end  (e),  on  the  contrary,  is  the  thickest  and  strongest  part  of 
the  bone,  and  might  with  propriety  be  named  the  head  of  the  clavicle ;  it"  articulates 
-  with  the  sternum,  projecting  beyond  the  concave  articular  surface  of  that  bone  in  all  di- 
Tections,  a  circumstance  which  renders  displacement  much  more  difficult. 

There  are  many  varieties  both  of  size  and  direction  in  the  body  and  ends  of  the  clav- 
icle. By  inspection  of  the  inner  or  outer  ends  of  the  clavicle,  even  in  the  living  body, 
we  may  judge  at  once  whether  the  individual  has  been  engaged  in  a  laborious  manual 
employment.  I  have  been  able,  from  the  simple  circumstance  of  a  marked  preponder- 
ance of  size  in  the  inner  end  of  the  left  clavicle,  to  declare  a  priori,  and  correctly,  that 
the  individual  on  whom  I  observed  it  was  left-handed.  In  some  clavicles  the  inner  half 
resembles  a  quadrangular  pyramid.  In  the  female  the  clavicle  is  much  more  slender, 
and  the  curvatures  are  less  pronounced,  than  in  the  male  :  the  strength  and  degree  of 
curvature  of  this  bone  are  proportionate  to  the  laborious  and  continued  exercise  of  the 
upper  extremity.  It  may,  therefore,  be  easily  conceived  how  much  importance  should 
be  attached  in  forensic  medicine  to  the  characters  of  a  bone,  the  examination  of  which 
would  of  itself  be  sufficient  to  determine  whether  the  body  to  which  it  belonged  were 
male  or  female,  and  whether  the  person  had  been  engaged  in  a  laborious  manual  occu- 
"'pation,  or  the  contrary. 

'     Cannexions. — The  clavicle  articulates  with  three  bones,  the  sternum,  the  scapula,  and 
often  with  the  first  rib. 

Internal  Structure. — With  regard  to  its  structure,  the  clavicle  appears  to  hold  a  middle 
place  between  the  long  bones  and  the  ribs ;  like  the  first,  in  fact,  it  possesses  a  medul- 
lary canal ;  but  it  approaches  the  structure  of  the  ribs  in  the  contracted  dimensions  of 
this  canal,  and  the  spongy  nature  of  its  ends.  In  examining  many  clavicles  belonging 
to  the  collections  of  the  Faculty  of  Medicine,  I  was  never  able  to  meet  with  one  that  had 
traces  of  a  medullary  canal  extending  throughout  its  entire  length. 

Development. — The  clavicle  makes  its  appearance  at  a  very  early  period,  about  the 
thirtieth  or  thirty-fifth  day ;  its  dimensions,  compared  with  those  of  the  other  bones  of 
the  thoracic  extremities,  present  considerable  variations  at  different  ages.  In  the  sec- 
ond month  of  foetal  life,  the  clavicle  has  already  acquired  nearly  three  lines  in  length ;  at 
this  time  it  is  at  least  four  times  the  length  of  the  humerus  and  femur.  After  the  com- 
mencement of  the  third  month  it  is  not  more  than  half  as  long  again  as  these  bones. 
At  the  end  of  the  third  month  it  is  still  longer  than  the  humerus,  which  does  not  exceed 
it  until  the  fourth  month.  Lastly,  in  the  foetus  at  the  full  period  the  humerus  does  not 
exceed  the  clavicle  in  length  by  more  than  a  fourth,  while  in  the  adult  it  becomes  twice 
as  long. 

The  clavicle  has  only  one  primitive  osseous  point ;  from  the  age  of  fifteen  to  twenty- 
eight  years,  a  complementary  or  epiphysary  point  is  developed,  under  the  form  of  a  very 
thin  plate,  at  the  anterior  part  of  the  sternal  end. 

The  Scapula  {Jig.  42). 

The  scapula,  or  shoulder  blade,  forms  in  man  the  back  part  of  the  shoulder ;  in  a  great 
number  of  animals  it  constitutes  the  entire  shoulder.    Placed  pig.  42. 

like  a  sort  of  shield  upon  the  back  part  of  the  thorax,  for  which 
it  serves  as  a  means  of  protection  against  extern2d  violence,  this 
bone  corresponds  with  the  lateral  part  of  the  spine,  which  it  ap- 
proaches or  quits  according  to  the  different  movements  of  the 
upper  extremity,  to  which  it  affords  a  movable  point  of  attach- 
ment. 

The  scapula  is  proportionally  larger  in  man  than  in  the  lower 
animals.  It  is  an  asjonmetrical  bone,  broad,  thin,  and  triangu- 
lar, presenting  two  surfaces,  three  borders,  and  three  angles. 

The  anterior  or  costal  surface  is  moulded,  as  it  were,  upon 
the  thorax  ;  it  is  concave  ;  the  concavity  being  named  the  sub- 
scapular fossa,  is  occupied  by  the  sub-scapular  muscle.  In  this 
we  observe  ridges  directed  obliquely  from  above  downward,  and 
from  without  inward,  which  receive  the  insertion  of  those  apo- 
neurotic layers  which  divide  the  substance  of  the  muscle.*  In 
a  well-formed  subject,  this  surface  should  be  exactly  fitted  to 
the  surface  of  the  thorax ;  but  when  the  chest  is  contracted,  as 
m  phthisical  patients,  the  scapula  does  not  participate  in  an  equal  degree  in  this  alter- 

*  The  direction  of  these  ridges  is  not  parallel  with  that  of  the  back  part  of  the  ribs,  but  crosses  them  at  an 
angle  ;  proving,  in  opposition  to  the  opinion  of  some  of  the  older  anatomists,  that  the  ridgres,  and  t^e  depres- 
sions which  separate  them,  are  not  the  result  of  pressure  exercised  bj;  the  ribs  on  the  antenor  surtace  of  tM 
scapula. 


5^  OSTEOLOGY. 

ation,  and  there  is,  consequently,  a  disproportion  and  change  of  relative  position,  to  such 
a  degree  that  the  scapulae  fonn  a  projection  behind,  and  are  in  some  measure  detached 
from  the  ribs  like  wings  :  hence  the  expression  of  scapula  data,  applied  to  the  external 
aspect  of  the  shoulder-blades  in  phthisical  persons. 

The  posterior  or  superficial  surface  {fig.  42)  is  divided  into  two  distinct  parts  by  a  tri- 
angular eminence  named  the  spine  of  the  scapula  (a).  This  spine,  situated  at  the  junc- 
tion of  the  upper  with  the  three  lower  fourths  of  the  bone,  arises  from  the  posterior  sur- 
face by  a  thick  edge,  which  traverses  the  entire  breadth  of  the  scapula ;  the  spine  is 
then  directed  horizontally  backward,  outward,  and  a  little  upward,  and  presents  for  our 
notice  an  upper  and  a  lower  surface,  which  form  part  of  the  supra-spinous  and  the  infra- 
spinous  fossae  ;  an  external  border  (c),  short,  concave,  thick,  and  smooth ;  and  a  posterior 
border  (a),  very  thick  and  sinuous,  which  has  at  its  inner  end  a  triangular  smooth  sur- 
face {d),  over  which  the  trapezius  muscle  glides.  This  border  is  placed  almost  imme- 
diately under  the  skin,  and  may  be  easily  traced  in  the  living  subject,  even  in  very  cor- 
pulent individuals.  It  gives  attachment  below  to  the  deltoid  muscle,  and  above  to  the 
trapezius,  which  is  inserted  into  nearly  the  whole  of  its  thickness. 

Instead  of  uniting  so  as  to  form  an  angle,  the  external  and  the  posterior  borders  of 
the  spine  are  continued  into  a  process  named  acromion  (c),  (from  aKpoQ,  the  summit,  and 
u^of ),  because  this  process  forms  the  highest  point  of  the  shoulder.  The  acromion  then 
forms  a  continuation  of  the  spine,  which  appears  to  be  its  root.  At  the  place  where  the 
spine  is  continuous  with  the  acromion,  there  is  a  contraction,  a  sort  of  pedicle,  above 
which  the  acromion  enlarges,  and  becomes  curved  into  a  triangular  arch  presenting  an 
anterior  and  a  posterior  surface,  a  superior  and  an  inferior  edge,  a  base  and  a  smiunit. 
The  posterior  surface  of  the  acromion  is  convex  and  rough,  and  is  separated  from  the 
skin  by  fibrous  tissue  and  a  synovial  bursa.  It  gives  attachment  to  the  trapezius  mus- 
cle, and  to  acromio-clavicular  Ugament.  The  anterior  surface  is  concave  and  smooth,  and 
corresponds  to  the  shoulder-joint.  The  upper  edge  has  a  facette,  which  articulates  with 
a  corresponding  surface  on  the  clavicle  ;  the  lower  edge  is  convex  and  rough ;  the  sutrv- 
mit  forms  the  highest  point  of  the  shoulder;  the  base  is  continuous  with  the  spine  ;  the 
narrowness  of  this  base  or  pedicle  of  the  acromion  explains  the  possibility  of  fractures 
at  this  point. 

The  whole  of  the  posterior  surface  of  the  scapula,  above  the  scapular  spine,  forms  the 
supra-spinmis  fossa  (/),  which  is  narrow  at  it  its  outer  part,  and  a  little  enlarged  and 
shallower  at  the  inner,  and  is  filled  by  the  supra-spinatus  muscle.  All  that  is  below  the 
spine  forms  the  infra-spinous  fossa  {g),  which  is  occupied  by  the  infra-spinatus  muscle. 
Towards  the  outer  part,  this  fossa  presents  a  vertical  ridge,  which  marks  off  a  narrow 
surface,  elongated  from  above  downward,  and  itself  divided  by  an  obUque  ridge  into  two 
smaller  surfaces,  the  superior  (A)  of  which  gives  attacliment  to  the  teres  minor  muscle, 
and  the  inferior  (i)  to  the  teres  major. 

Of  the  three  borders  or  costa  of  the  scapula,  the  internal,  which  is  also  called  the  base, 
posterior  costa,  vertebral  or  spinal  border  (k  d  I),  is  the  longest  of  the  three  in  the  human 
subject ;  in  the  lower  animals  it  is  the  shortest.  It  is  thin,  slopes  from  without  inward 
in  the  upper  fourth  of  its  extent,  and  from  within  outward  in  the  three  inferior  fourths, 
which  gives  it  an  angular  form.    The  spine  of  the  scapula  meets  the  base  at  this  angle  {d). 

The  superior  or  cervical  border,  or  superior  costa  (k  r),  the  shortest  and  thinnest ;  we 
observe  on  it  a  notch  (r)  of  variable  size,  which  is  converted  into  a  foramen  by  means  of 
a  ligament,  and  gives  passage  to  the  supra-scapular  nerve ;  rarely  to  the  vessels  of  that 
name. 

The  external  or  axillary  border,  or  inferior  costa  {s  I),  is  the  thickest  part  of  the  scap- 
ula. It  is  separated  from  the  thorax  by  an  interval,  the  extent  of  which  determines  the 
depth  of  the  cavity  of  the  axiUa.  Its  thickness  increases  from  the  lower  to  the  upper  part, 
where  it  terminates  in  the  glenoid  cavity.  There  is  a  depression  (s)  from  which  the 
long  head  of  the  triceps  muscle  arises. 

Angles. — Two  of  the  three  angles  of  the  scapula  are  intended  for  the  attaclmient  of 
the  principal  muscles  belonging  to  this  bone ;  the  third  enters  into  the  formation  of  the 
shoulder-joint.  , 

The  internal  angle  {k)  is  that  which  approaches  most  to  a  right  angle.  In  robust  subjects 
it  presents  a  marked  impression  for  the  insertion  of  the  levator  anguli  scapulae  muscle. 

The  inferior  angle  (JL)  is  very  acute,  and  is  marked  internally  by  inequalities  for  the  at- 
tachment of  the  serratus  magnus.  This  angle  is  only  covered  by  the  skin  and  the  latis- 
simus  dorsi  muscle,  and  is,  consequently,  more  liable  than  the  other  two  to  fracture  from 
external  violence. 

The  external  or  glenoid  angle  (m)  is  the  thickest  part  of  the  scapula ;  it  is  hollowed  into 
an  oval  cavity,  the  long  diameter  of  which  is  vertical,  and  the  small  end  of  the  oval  up- 
permost. This  cavity,  called  the  glenoid  cavity  (m)  of  the  scapula,  belongs  to  the  shoul- 
der-joint ;  it  is  supported  by  a  contracted  portion  (?0  called  tlie  neck  of  the  scapula,  and 
is  surmounted  by  a  strong  process  (o)  named  coracoul,  from  a  fancied  resemblance  to  the 
bill  of  a  raven.  This  process  is  directed  outward  ami  forward  like  a  finger  in  a  state  of 
semiflexion ;  its  lower  surface,  which  looks  oiitwanl,  lo  confmve  and  smooth,'  and  is 


THE  SHOULDER  IN  GENERAL.  77 

curved  to  correspond  with  the  head  of  the  humerus ;  its  upper  surface  is  convex  and 
rough,  and  articulates  with  the  clavicle.  Its  summit  is  rough,  and  affords  attachment 
to  muscles.  The  coraco-acromial  ligament  is  attached  to  its  posterior  border,  the  fecto- 
ralis  minor  muscle  and  the  anterior  fibres  of  the  coraco-clavicular  ligaments  to  its  ante- 
rior, while  the  short  head  of  the  biceps  and  the  coraco-brachialis  muscles  united  arise 
from  its  summit. 

Connexions. — The  scapula  is  articulated  with  the  clavicle  and  the  humerus. 

Internal  Structure. — There  is  very  little  spongy  substance  in  the  composition  of  the 
scapula,  as  may  be  well  observed  in  the  supra  and  infra  spinous  fossae,  where  we  can 
scarcely  make  use  of  a  file,  without  breaking  through  the  very  thin  lamina  of  compact  tis- 
sue of  which  the  bone  is  composed  at  these  points.  The  spongy  tissue  occupies  the  ax- 
illary border,  the  spine,  the  articular  angle,  the  acromion,  and  the  coracoid  process. 

Devclopimnt. — The  scapula  is  developed  from  six  points  :  one  primitive  for  the  body 
of  the  bone,  and  five  epiphysary  or  complementary,  viz.,  one  for  the  coracoid  process, 
two  for  the  acromion,  one  for  the  posterior  border,  and  one  for  the  inferior  angle. 

The  osseous  point  of  the  body  appears  towards  the  end  of  the  second  month  of  utero- 
gestation,  in  the  infra-spinous  fossa,  under  the  form  of  an  irregularly  quadrilateral  plate 
of  bone,  on  the  surface  of  which  we  cannot  perceive  any  vestige  of  the  scapular  spine. 
It  is  not  until  the  third  month  that  this  process  becomes  apparent ;  and  at  that  period 
the  ossification  has  made  so  little  progress  towards  the  upper  part  of  the  bone,  that  the 
spine,  which  subsequently  is  situated  below  the  upper  fourth  of  the  scapula,  is  then  suffi- 
ciently elevated  to  project  beyond  the  upper  part  of  that  bone.  The  spine  is  never  devel- 
oped from  a  separate  point,  but  sprouts,  as  it  were,  from  the  posterior  surface  of  the  bone. 

The  osseous  point  of  the  coracoid  process  appears  sometimes  at  birth,  but  generally 
during  the  first  year. 

The  osseous  germ  of  the  base  of  the  acromion  process,  which  has  a  rounded  form,  is 
developed  before  the  fifteenth  year.  That  of  the  summit  of  the  acromion  does  not  be- 
come visible  until  from  the  fifteenth  to  the  sixteenth  year ;  that  is  the  time  at  which  the 
coracoid  process  is  united  to  the  body  of  the  bone.  It  is  very  variable  in  its  shape,  be- 
ing sometimes  like  a  narrow  band,  sometimes  forming,  by  itself,  the  greatest  part  of  the 
process. 

The  osseous  point  of  the  inferior  angle  of  the  scapula  is  developed  during  the  course 
of  the  fifteenth  year. 

The  osseous  point  of  the  vertebral  border  extends  along  the  whole  posterior  costa  as 
a  long  marginal  epiphysis,  analogous  to  that  which  we  shall  afterward  describe  as  exist- 
ing on  the  haunch  bone.     It  is  not  formed  till  the  seventeenth  or  eighteenth  year. 

The  union  of  these  different  osseous  points  does  not  commence  until  the  fifteenth 
year,  at  which  time  the  coracoid  process  becomes  joined  to  the  body  of  the  bone.  The 
other  points  unite  at  various  periods,  which  have  not  yet  been  determined  with  much 
exactness.  The  osseous  point  of  the  vertebral  border  remains  the  longest  separate  of 
all.  The  union  of  all  these  points  is  not  completed  until  the  time  when  the  growth  of 
the  body  is  terminated. 

The  Shoulder  in  general. 

Considered  as  forming  only  one  piece,  the  shoulder  represents  a  bony  girdle  intended 
to  serve  as  a  fulcrum  to  the  upper  extremities.  This  girdle  is  incomplete  in  front  oppo- 
site the  sternum,  and  behind  in  the  region  of  the  vertebral  column.  From  this  it  follows, 
that  the  two  shoulders  are  independent  in  their  motions,  while  the  pelvis,  which  forms  an 
analogous  structure  for  the  lower  extremities,  is  a  continuous  whole,  the  different  parts 
of  which  cannot  move  upon  each  other.  The  shoulders  are  fixed  upon  the  upper  part  of 
the  thorax,  and  so  greatly  increase  its  apparent  dimensions,  that  the  chest,  when  they 
are  attached,  resembles  a  cone  with  the  base  upward,  while  in  its  true  shape  it  is  a  cone 
with  the  base  below.  The  shoulder  is  moulded  exactly  upon  the  thorax  in  front  and  be- 
hind ;  on  the  outside  it  is  separated  from  it  by  an  interval  which  forms  the  apex  of  the 
axilla. 

The  circumstance  which  principally  determines  the  transverse  breadth  of  the  shoul- 
ders in  the  female  is  the  length  of  the  clavicle ;  in  the  male,  it  is  the  breadth  of  the 
scapula.  The  length  of  the  clavicle  and  the  width  of  the  chest  in  front  and  at  the  upper 
part,  in  the  female,  are  evidently  connected  with  the  large  size  of  the  mammae  ;  and  the 
greater  development  of  the  scapulae  in  the  male  evidently  corresponds  with  his  greater 
muscular  power. 

General  Development  of  the  Shoulder. 
The  development  of  the  shoulder  is  remarkable  for  its  precocity.  For,  on  the  one 
hand,  the  considerable  length,  the  well-defined  form,  and  the  double  curvature  of  the 
fcetal  claAdcle,  at  a  time  when  all  the  long  bones  are  still  straight,  prove  the  rapidity  with 
which  this  part  of  the  skeleton  is  developed.  On  the  other  hand,  the  size  of  the  scapula, 
which  is  already  considerable,  and  the  very  advanced  state  of  ossification  of  the  part  that 
sustains  the  glenoid  cavity,  which  enables  it  very  soon  to  afford  a  sufficient  resistance  to 


OSTEOLOGY. 


the  movements  of  the  humerus,  equally  concur  in  demonstrating  the  same  fact.  This 
rapid  development  cannot  be  attributed  to  the  near  vicinity  of  the  heart  and  great  vessels, 
because  the  sternum  and  the  cervical  vertebrae,  which  are  still  more  closely  approximated 
to  the  centre  of  the  circulation,  are  proportionally  much  slower  in  their  ossification. 

The  Arm. 
The  Humerus  {Jig.  43). 
The  humerus,  or  bone  of  the  arm,  is  situated  between  the  shoulder  and  the  forearm,  at 
-^  ^         the  side  of  the  thorax.     It  is  the  longest  and  the  strongest  of  all  the 
/*'■     ■        bones  of  the  upper  extremity.    It  is  proportionally  shorter  in  individuals 
"'^^  ^       of  the  Caucasian  or  white  races  than  in  the  Ethiopian,  which  in  them, 
^t   in  this  respect,  presents  some  analogy  to  the  ape  tribes.     Its  direction 
is  vertical,  that  is,  parallel  to  the  axis  of  the  trunk,  but  with  some  de- 
gree of  obhquity  downward  and  inward.    This  obliquity  is  much  great- 
er in  the  femur,  the  bone  of  the  lower  extremity  which  corresponds 
with  the  humerus.     The  distance  between  the  humeri  is  much  greater 
in  man  than  in  quadrupeds,  corresponding  with  the  different  shape  of 
the  thorax,  which,  as  we  have  before  observed,  is  flattened  from  before 
backward  in  the  human  subject,  and  laterally  in  quadrupeds.     The  hu- 
merus is  not,  like  the  femur,  curved  as  regards  its  axis,  but  it  presents 
a  very  marked  curvature  of  torsion,  which  gives  rise  to  a  remarkable 
groove,  that  lodges  the  deep  artery  and  the  radial  nerve,  as  they  turn 
round  the  bone  in  a  part  of  their  course. 

The  humerus  is  a  long,  asymmetrical  bone,  presenting  for  examina- 
tion a  body  (a)  and  two  extremities  {b  c) ;  the  upper  of  these  is  rounded, 
and  is  called  the  head  (b). 

The  lower  half  of  the  body  of  the  humerus  is  prismatic  and  triangular ; 
the  upper  is  cylindrical.  It  has  three  surfaces,  an  external,  an  internal, 
and  a  posterior ;  and  three  edges,  an  external,  an  internal,  and  an  anterior. 
The  external  surface  {d  e)  presents,  1.  A  remarkable  muscular  impres- 
sion, shaped  like  the  letter  V,  with  the  point  turned  downward ;  this  is 
the  deltoid  impression  {d),  and  is  generally  situated  below  the  upper  third 
of  the  bone,  but  sometimes  at  the  middle  ;  2.  The  groove  of  torsion  (/), 
directed  obliquely  downward  and  forward,  the  depth  of  which  is  always 
proportional  to  the  prominence  of  the  deltoid  impression,  immediately 
below  which  it  is  placed.  Below  the  groove,  the  external  surface  (c) 
looks  forward,  and  is  slightly  concave,  to  allow  of  the  origin  of  the 
I  {     brachialis  inter nus  muscle. 

The  internal  surface  (a)  is  an  oblique  plane,  looking  forward  and  in- 
ward ;  the  brachial  artery  runs  along  it,  and  therefore  it  is  of  impor- 
tance to  he  well  acquainted  with  the  obliquity  of  the  surface,  in  order  that,  when  it  is 
necessary  to  compress  the  vessel,  force  may  be  applied  in  the  proper  direction.  Its  up- 
per part,  which  looks  forward,  is  broader  than  the  lower,  which  is  turned  inward.  On 
this  surface  we  observe,  1.  The  bicipital  groove  (g),  which  will  be  particularly  noticed  af- 
terward ;  2.  The  principal  nutritious  foramen  {v)  of  the  humerus,  which  passes  down- 
ward into  the  interior  ;*  3.  An  obscurely-marked  impression  for  the  coraco-brachialis 
muscle. 

The  posterior  surface  is  smooth,  round,  and  much  broader  below  than  above ;  it  is  cov- 
ered by  the  triceps. 

Of  the  three  edges,  the  anterior  (h  i)  is  a  rough  ridge,  round  and  blunt  below,  bifurcated 
above,  so  as  to  form  the  two  borders  of  the  bicipital  groove  (g),  which  is  one  of  the  lar- 
gest and  deepest  of  all  the  tendinous  grooves  in  the  body,  and  lodges  the  tendon  of  the 
long  head  of  the  biceps.  The  two  borders  of  this  groove,  the  external  (h)  and  the  inter- 
nal {k),  are  very  prominent  and  rough,  and  afford  attachment  to  powerful  muscles  ;  the 
former  to  the  peetoralis  major,  and  the  latter  to  the  latissimus  dorsi  and  teres  major.  It 
should  be  remarked,  that  the  anterior  branch  of  the  V  represented  by  the  deltoid  impres- 
sion is  blended  with  the  anterior  edge  of  the  bicipital  groove,  and  greatly  increases  its 
prominence. 

The  other  two  edges  of  the  humerus,  viz.,  the  external  {d  I)  and  the  internal  (v  r),  are 
olunt,  and  scarcely  distinguishable  in  their  upper  two  thirds,  but  sharp  and  prominent  at 
iheir  lower  parts,  especially  the  external  edge,  which  curves  forward  and  gives  attach- 
ment to  a  great  number  of  muscleig.  This  edge  is  also  interrupted  in  its  course  by  the 
groove  of  torsion. 

The  lower  or  cubital  extremity  (c)  of  the  humerus  is  flattened  from  before  backward, 
with  a  transverse  diameter  four  times  longer  than  the  antero-posterior.  It  presents  a 
series  of  eminences  and  depressions  arranged  in  the  same  transverse  line,  viz.,  counting 

*  There  are  some  varieties  in  the  situation  of  the  nutritious  foramen.  I  have  seen  it  on  the  external,  or 
even  posterior  surface  of  the  bone. 


THE    ULNA.  7g^ 

Irom  without  inward,  1.  An  exteriml  tuberosity  (I),  called  eptcondyle  by  Chaussier,  which 
forms  a  continuation  of  the  outer  border,  and  gives  insertion  to  almost  all  the  muscles 
on  the  back  of  the  forearm ;  2.  The  small  head  (m)  of  the  humerus  {humeral  condyle  of 
Chaussier),  a  rounded  eminence,  bent  forward  and  oblong  from  before  backward.  The 
small  head  articulates  with  the  radius,  and  is  surmounted  in  front  by  a  superficial  de- 
pression, intended  to  receive  the  rim  of  the  shallow,  cup-like  cavity  on  the  top  of  the 
radius ;  3.  An  articular  furrow  (n),  extending  obliquely  from  behind  forward,  and  from 
without  inward,  and  separating  the  small  head  from  4.  The  trochlea  (c),  or  articulur  pulley 
of  the  humerus,  which  is  also  directed  from  behind  forward,  and  from  without  inward,  ia 
excavated  like  the  groove  of  a  pulley  in  its  long  diameter,  and  the  inner  border  of  which 
descends  much  lower  than  the  outer.  This  trochlea  articulates  with  a  corresponding 
surface  on  the  ulna,  and  is  surmounted  in  front  by  a  small  cavity  named  coronoid  (o),  and 
behind  by  a  much  larger  depression,  the  olecranoid  cavity.  These  two  cavities,  the  ante- 
rior of  which  receives  the  coronoid  process  of  the  ulna  during  flexion  of  the  forearm,  and 
the  posterior,  the  olecranon,  during  its  extension,  are  only  separated  from  each  other  by 
a  very  thin,  translucent  lamina  of  bone,  which  is  sometimes  perforated,  so  that  they 
communicate  with  each  other ;  5.  The  internal  tuberosity  or  epitrochlea  (r),*  which  is  bent 
inward,  is  much  more  prominent  than  the  external,  forming  a  projection  which  can  be 
easily  felt  under  the  skin,  and  gives  attachment  to  almost  all  the  muscles  situated  on 
the  anterior  aspect  of  the  forearm. 

The  superior  or  scapular  extremity  of  the  humerus,  much  larger  than  the  inferior,  pre- 
sents, 1.  The  head  (i),  a  sphenoidzil  eminence,  forming  about  one  third  of  a  sphere.  It 
articulates  with  the  glenoid  cavity  of  the  scapula,  and  is  bounded  in  the  two  upper  thirds 
of  its  circumference  by  a  circular  furrow.  The  constriction  resulting  from  this  furrow 
has  been  improperly  called  the  anatomical  neck  of  the  humerus  (*).  The  only  part  which 
could  possibly  be  considered  as  the  neck,  is  a  portion  of  the  bone  which  projects  on  the 
inner  side,  and  appears  to  support  the  head.  It  is  of  importance  not  to  confound  the 
circular  constriction,  which  we  have  mentioned  as  being  called  the  anatomical  neck, 
with  what  is  denominated  the  surgical  neck  (at  k),  which  is  nothing  more  than  that  slight- 
ly contracted  portion  of  the  bone  which  supports  the  whole  of  its  upper  extremity.  The 
presence  of  the  anatomical  neck  of  the  humerus,  and  the  inclination  of  the  articular  sur- 
face, cause  the  axis  of  this  surface  to  form  an  obtuse  angle  with  the  axis  of  the  rest  of 
the  bone.  2.  Two  other  eminences,  named  greater  {t)  and  lesser  (u)  tuberosities  {trochiter 
and  trochin  of  Chaussier),  and  which  might  be  called  the  great  and  small  trochanters  of  the 
humerus :  they  are  separated  by  the  bicipital  groove.  The  smaller,  which  is  in  front, 
gives  attachment  to  the  sub-scapular  muscle ;  the  larger,  which  is  external,  presents 
three  surfaces,  each  of  which  gives  attachment  to  a  muscle,  viz.,  to  the  supra  spinatus, 
infra  spinatus,  and  teres  minor. 

Connexions. — The  humerus  articulates  with  the  scapula,  the  radius,  and  the  ulna. 

Internal  Structure. — The  two  extremities  of  the  humerus  are  cellular ;  the  middle  is 
compact.     It  has  a  very  large  medullary  canal. 

Development. — The  humerus  is  developed  from  seven  points  ;  one  for  the  body,  two 
for  the  upper  end,  and  four  for  the  lower. 

The  first  osseous  point  appears  in  the  middle  of  the  bone  from  the  thirtieth  to  the  for- 
tieth day,  in  form  of  a  small  solid  cylinder,  which  progressively  extends  towards  both 
extremities.  At  birth,  and  during  the  course  of  the  first  year,  the  extremities  are  still 
cartilaginous.  The  ossific  point  of  the  head  of  the  humerus  appears  at  the  commence- 
ment of  the  second  year  ;  and  that  of  the  great  tuberosity  from  the  twenty-fourth  to  the 
thirtieth  month.  It  has  not,  in  my  opinion,  been  proved  that  there  is  any  special  point  for 
the  lesser  tuberosity.  The  ossification  of  the  lower  end  of  the  bone  commences  after  that 
of  the  upper.  At  two  years  and  a  half,  an  osseous  point  is  developed,  corresponding  to 
the  small  head  or  condyle  of  the  humerus ;  at  seven  years,  another  nodule  appears  in  the 
epitrochlea ;  at  twelve  years,  a  third  point,  which  forms  the  inner  edge  of  the  trochlea ; 
and,  lastly,  at  sixteen  years,  a  fourth  point  for  the  epicondyle. 

The  two  points  of  ossification  of  the  upper  end  of  the  bone  unite  from  the  eighth  to 
the  ninth  year.  The  four  points  of  the  lower  end  are  joined  together  in  the  following 
order :  in  the  twelfth  year,  the  two  points  of  the  trochlea ;  in  the  sixteenth  year,  the  troch- 
lea, the  epicondyle,  and  the  small  head.  The  two  extremities  are  united  to  the  shaft 
from  the  eighteenth  to  the  twentieth  year.  The  union  of  the  lower  end  always  precedes 
that  of  the  upper  by  one  year,  although  the  latter  first  becomes  ossified. 

The  Forearm. 

The  Ulna  (jig.  44-). 
The  ulna,  or  cubitus,  so  called  because  it  forms  the  elbow,  is  situated  between  the  hu- 
merus and  the  carpus,  on  the  inner  side  of  the  radius,  with  which  it  articulates  above 
and  below,  but  from  which  it  is  separated  in  the  middle.     It  is  the  longer  and  the  lar- 
ger of  the  bones  of  the  forearm.     When  the  whole  limb  is  in  the  vertical  position,  this 

*  Epitrochlea,  from  M,  upon,  and  rpox'^'O)  apuHey.   Epicondyle,  from  ini,  upon,  and  KivSv^oi,  an  eminence. 


OSTEOLOGY. 


Fig  44. 


H 


bone  slants  a  little  from  above  downward  and  outward.  It  is  a  long  and 
asymmetrical  bone,  much  larger  above  than  below,  prismatic,  triangular,  and 
slightly  twisted  upon  itself:  it  is  divided  into  a  shaft  and  extremities. 

The  body  or  shaft  (o)  of  the  bone  is  larger  above  than  below,  is  slightly  curv- 
ed forward,  and  has  three  surfaces  and  three  edges. 

The  anterior  surface  (a)  is  broad  above,  and  becomes  gradually  narrower  to- 
wards the  lower  part.  On  it  we  observe  the  nutritious  foramen  (above  a), 
which  penetrates  from  below  upward,  i.  e.,  in  precisely  the  opposite  direction 
of  the  nutritious  canal  in  the  humerus.  This  surface  is  slightly  grooved,  and 
gives  origin  to  the  flexor  profundus  muscle. 

The  posterior  surface  {d)  is  slightly  convex,  and  is  divided  longitudinally  by 
a  prominent  vertical  line  into  two  portions,  the  inner  of  which  is  the  broader. 
A  second  oblique  line  placed  at  the  upper  part  forms  a  triangular  space  occu- 
pied by  the  anconeus  muscle.  The  internal  surface  is  very  broad  above,  and 
much  smaller  at  its  lowef  end,  which  is  immediately  subcutaneous.  It  is 
smooth  throughout  its  whole  extent.  Of  the  three  edges,  the  external  (e)  is 
the  sharpest,  especially  in  the  middle  ;  it  commences  above,  below  a  small  ar- 
ticular surface,  the  lesser  sigmoid  cavity,  and  is  effaced  at  the  lower  part  of  the 
bone.  It  gives  attachment  to  the  interosseous  ligament,  a  sort  of  fibrous  mem- 
brane stretched  between  the  radius  and  ulna.  The  anterior  edge  {n  fm)  is  blunt, 
and  is  intended  for  muscular  insertions  ;  towards  its  lower  part  it  bends  slight- 
ly forward,  becomes  rough,  and  terminates  in  front  of  a  pointed  eminence 
called  the  styloid  process  (m) :  it  commences  above  by  a  very  marked  projec- 
tion (w)  on  the  inside  of  an  eminence  named  the  coronoid  process  of  the  ulna. 
The  posterior  edge  commences  below  the  olecranon  by  a  bifurcated  extremity ; 
it  terminates  insensibly  towards  the  lower  fourth  of  the  bone  ;  this  edge  may  be  felt  be- 
neath the  skin  throughout  its  whole  extent. 

The  superior  or  humeral  extremity  (J)  of  the  ulna  presents  a  considerable  enlargement ; 
it  is  hollowed  in  front  into  a  hook-hke  cavity,  which  articulates  with  the  trochlea  of  the 
humerus,  to  the  shape  of  which  it  is  adapted.  This  cavity,  which  forms  almost  half  the 
circumference  of  a  circle,  is  called  the  great  sigmoid  cavity  (fi  g  h)  of  the  ulna,  because  it 
has  been  compared  to  the  letter  sigma  of  the  Greek  alphabet.  It  has  a  vertical  branch, 
which  forms  the  olecranon  process  (6),  and  a  horizontal  one  named  the  coronoid  process  (/«). 
There  is  a  sort  of  constriction  at  the  place  (g)  where  these  two  branches  meet ;  this  is 
the  weakest  point  of  the  upper  end  of  the  ulna,  and  is,  consequently,  the  almost  invariable 
seat  of  fractures  of  the  olecranon.  The  olecranon  (i),  so  named  from  uMvrj,  the  elbow, 
and  Kpuvov,  the  head,  because  it  constitutes  the  most  prominent  part,  or  head  of  the  elbow, 
presents,  1.  A  posterior  surface,  smooth  above,  and  rough  and  irregular  below,  where  it 
gives  insertion  to  the  triceps  ;  2.  An  anterior  or  articular  surface,  concave,  divided  by  a 
vertical  ridge  into  two  lateral  parts  of  unequal  magnitude  ;  this  is  articulated  to  the  troch- 
lear surface  of  the  humerus  ;  3.  Two  borders,  more  or  less  rough  in  different  subjects, 
which  afford  attachments  to  the  triceps  muscle  ;  4.  A  base,  with  the  constriction  we  have 
before  described  ;  5.  The  summit,  having  the  form  of  a  curved  beak,  which  is  received  into 
the  olecranal  cavity  of  the  humerus  during  extension  of  the  forearm. 

The  horizontal  branch  of  the  sigmoid  cavity,  or  the  coronoid  process  Qi),  presents,  1.  A 
rough  inferior  surface  (i),  on  which  the  brachiahs  anticus  muscle  is  inserted  ;  2.  A  supe- 
rior surface  divided  into  two  unequal  parts  by  a  ridge,  which  is  a  continuation  of  that 
which  divides  the  articular  surface  of  the  olecranon ;  3.  An  internal  rough  edge  (n),  bent 
inward,  and  giving  insertion  to  the  internal  lateral  ligament  of  the  elbow-joint ;  4.  An 
external  edge  marked  by  a  smaU  cavity,  which  is  oblong  from  before  backward,  and 
slightly  concave  in  the  same  direction,  and  is  called  the  lesser  sigmoid  cavity  (Jc)  of  the 
ulna,  to  which  the  head  of  the  radius  is  articulated  ;  below  this  small  cavity  is  a  rough, 
triangular,  and  deeply  excavated  surface,  to  which  the  supinator  brevis  muscle  is  attach- 
ed ;  5.  An  anterior  sinuous  edge,  with  a  projection  or  beak,  which  is  received  into  the 
coronoid  cavity  of  the  humerus  during  flexion  of  the  forearm. 

The  lower  extremity  of  the  ulna  presents  a  small  rounded  enlargement  (c),  which  has 
been  called  the  head  of  the  ulna.  We  observe  on  the  outside  an  articular  facette  (Z),  con- 
-vex,  and  elongated  from  before  backward,  which  is  received  into  a  corresponding  con- 
cave surface  on  the  lower  extremity  of  the  radius.  On  the  inner  side  of  this  head  a 
vertical  cylindrical  process  arises,  called  styloid  process  of  the  ulna  (m),  the  point  of  which 
gives  attachment  to  the  internal  lateral  ligament  of  the  wrist-joint.  The  head  of  the 
ulna  presents  below  a  smooth  surface,  which  articulates  with  the  cuneiform  bone,  a 
movable  fibro-cartilage  being  interposed ;  it  is  separated  from  the  styloid  process  behind 
by  a  groove  for  the  passage  of  a  tendon,  and  on  the  inside  by  a  sUght,  irregular  depres- 
sion, to  which  the  triangular  fibro-cartilage  is  attached. 

Connexions. — The  ulna  articulates  with  the  humerus,  the  radius,  and  the  cuneiform 
bone. 

Internal  Structure. — The  shaft  of  the  ulna  is  compact ;  the  two  extremities  are  cellu- 
lar, especially  the  upper,  the  olecranon  process  of  which  resembles  a  short  bone,  both 


THE    RADIUS.  81 

in  form  and  stmctuvo.     Sometimes,  even,  as  Rosenmullcr  has  observed,  this  process 
constitutes  really  a  short  bone,  entirely  separated  from  the  ulna. 

Development. — The  ulna  is  developed  from  three  points ;  one  for  the  shaft,  and  one  for 
each  extremity.  The  osseous  point  of  the  body  appears  first  from  the  thirty-fifth  to  the 
fortieth  day,  or  a  little  later  than  that  of  the  humeiiis.  At  birth,  the  extremities  are 
entirely  cartilaginous  ;  they  do  not  begin  to  ossify  untQ  the  sixth  year,  the  lower  one 
having  the  priority.  The  coronoid  process  is  formed  by  extension  of  the  ossific  point 
of  the  shaft.  The  nodule  of  the  olecranon  appears  about  the  seventh  or  eighth  year. 
The  upper  extremity  is  united  to  the  shaft  from  the  fifteenth  to  the  sixteenth  year ;  the 
lower,  from  the  eighteenth  to  the  twentieth  year. 

The  Radius  {fig.  45). 

The  raiius,  so  named  because  it  has  been  compared  to  the  spoke  of  a  wheel,  is  situa- 
ted between  the  hiunerus  and  the  carpus,  on  the  outside  of  the  ulna,  to  which     ^^    ^j 
it  is  contiguous  above  and  below,  and  from  which  it  is  separated  in  the  mid-  '  „| 

die  by  the  interosseous  space.  It  is  somewhat  smaller  and  shorter  than  the 
ulna,  and  has  a  vertical  direction.  It  is  a  long  and  asyiiunetrical  bone,  pris- 
matic and  triangular  in  its  shape  ;  its  lower  end  is  the  larger,  and  its  shaft  is 
slightly  curved  ;  it  consists  of  a  shaft  and  extremities. 

The  shaft  (o),  smaller  above  than  below,  presents  a  slight  curvature  with 
the  concavity  looking  inward :  this  circumstance  increases  the  distance  be- 
tween the  radius  and  ulna,  i.  e.,  the  interosseous  space.  It  has  three  surfa- 
ces, an  anterior,  a  posterior,  and  an  external,  and  three  edges.  The  anterior 
surface  (o),  narrow  above  and  broad  below,  presents  (above  o)  the  orifice  of 
the  nutritious  canal,  which,  like  that  of  the  ulna,  runs  upward,  or  in  an  oppo- 
site direction  to  that  of  the  humerus.  It  is  somewhat  grooved,  and  gives  at- 
tachment to  the  flexor  longus  pollicis,  and  below  to  the  pronator  quadratus  mus- 
cles. The  posterior  surface,  also  slightly  hollowed,  gives  attachment  to  sev- 
eral of  the  deep-seated  muscles  on  the  back  of  the  forearm.  The  external 
surface,  convex  and  rounded,  is  of  equal  breadth  in  almost  its  whole  extent, 
and  presents  near  the  middle  a  rough  surface  for  the  insertion  of  the  prona- 
tor teres. 

Of  the  three  edges,  one  is  anterior,  the  other  posterior,  and  the  third  inter- 
nal :  the  anterior  edge  (t  r  s)  is  blunt  superiorly ;  it  commences  below  a  marked 
projection,  named  the  bicipit£d  tuberosity,  or  tubercle  of  the  radius  {t) ;  from 
this  point  it  passes  obliquely  outward,  and  terminates  below,  in  front  of  an- 
other eminence  c£dled  the  styloid  process  (s)  of  the  radius.  The  posterior  edge,  less 
prominent  than  the  anterior,  forms  a  scarcely  perceptible  demarcation  between  the  two 
surfaces  which  it  separates ;  it  is  pretty  well  marked  in  the  middle  of  the  bone,  but 
hardly  distinguishable  above  and  below.  The  internal  edge  {t  g)  is  sharp,  and  has  the 
appearance  of  a  ridge ;  it  commences  below  the  bicipital  tuberosity,  and  extends  to  a 
small  articular  cavity  (^),  on  the  inner  side  of  the  lower  end  of  the  bone.  This  edge 
gives  attachment  to  the  interosseous  ligament  in  its  whole  extent. 

The  superior  or  humeral  extremity  (m),  called  also  the  head  of  the  radius,  expands  in 
form  of  a  shallow  but  regularly-shaped  cup,  the  cavity  corresponding  with  the  small  head 
of  the  humerus,  which  it  partially  receives.  It  is  bounded  by  a  circular  border  with  a  ver- 
tical articular  surface  (»),  varying  in  breadth  in  different  points,  being  nearly  three  lines 
broad  on  the  inside,  where  it  is  in  contact  with  the  lesser  sigmoid  cavity  of  the  ulna.  The 
head  of  the  radius  is  supported  by  a  constricted  portion,  or  neck  {w),  of  a  cylindrical 
form,  and  five  or  six  lines  in  length,  which  is  obhquely  directed  from  above  downward, 
and  from  without  inward.  At  the  junction  of  the  neck  and  body  of  the  radius,  on  the 
inside,  we  see  a  very  marked  process,  called  bicipital  tuberosity  (t).  Its  posterior  half  is 
rough,  where  it  gives  attachment  to  the  tendon  of  the  biceps ;  the  anterior  is  smooth, 
and  the  tendon  of  the  biceps  glides  over  it  before  reaching  its  point  of  insertion. 

The  inferior  or  carpal  extremity  {x),  which  is  the  largest  part  of  the  radius,  is  irregu- 
larly quadrilateral.  Its  lower  surface  is  articular,  smooth,  concave,  irregularly  triangu- 
lar, and  divided  by  a  small  antero-posterior  ridge  into  two  parts  :  an  internal,  which  ar- 
ticulates with  the  semilunar  bone  of  the  Avrist,  and  an  external,  which  articulates  with 
the  scaphoid.  In  the  outside  of  this  surface  we  observe  a  pyramidal,  triangular  pro- 
cess, slightly  bent  outward ;  this  is  the  styloid  process  (s)  of  the  radius,  shorter  and  much 
thicker  than  the  styloid  process  of  the  ulna,  and,  like  it,  giving  attachment  to  one  of  the 
lateral  ligaments  of  the  wrist-joint.  The  circumference  of  this  end  of  the  bone  exhibits 
in  front  some  inequcdities,  to  which  the  anterior  ligament  of  the  wrist  is  attached ;  Se- 
hind  and  on  th«  outside,  it  is  marked  by  the  following  tendinous  grooves,  viz.,  proceed- 
ing from  without  inward,  1.  An  oblique  groove  on  the  external  surface  of  the  styloid  pro- 
cess, which  shows  the  trace  of  a  longitudinal  division  marking  out  two  secondary  fur- 
rows. 2.  A  groove  bounded  by  projecting  edges,  and  subdivided  into  two  secondary 
ones  by  a  longitudinal  ridge,  less  elevated  than  the  lateral  border.  3.  A  somewhat  deep- 
Li 


6s  OSTEOLOGY. 

er  groove,  also  divided  into  two  secondary  furrows  of  unequal  dimensions  by  a  ver3f 
prominent  line.* 

On  the  inside  (g-),  the  lower  end  of  the  radius  is  slightly  excavated,  to  articulate  witii 
the  carpal  extremity  of  the  ulna. 

Connexion. — ^The  radius  articulates  with  the  humerus,  the  ulna,  the  scaphoid,  and 
semilunar  bones. 

Internal  Structure. — The  two  extremities  of  the  radius  are  cellular,  and  are  covered  by 
a  very  brittle  layer  of  compact  tissue  :  this  is  more  remarkably  the  case  at  the  lowei 
part  of  the  bone,  where  fractures  most  usually  occur.  The  shaft  is  almost  entirely  form- 
ed of  compact  tissue,  and  has  a  very  narrow  medullary  canal. 

Development. — The  radius  is  developed  from  three  points,  one  for  the  body,  and  oi  «j 
for  each  extremity.  The  osseous  point  of  the  body  appears  some  days  before  that  of 
the  ulna :  the  lower  extremity  is  developed  about  the  second  year ;  the  upper,  at  nine 
years.  The  upper  extremity,  which  is  last  in  beginning  to  ossify,  becomes  united  to  the 
body  of  the  bone  about  the  twelfth  year,  while  the  lower  extremity  is  not  joined  until 
from  the  eighteenth  to  the  twentieth  year. 

The  Hand  {fig.  46). 

The  hand  is  the  last  part  of  the  upper  extremity.    Accustomed  as  we  are  to  admire 
jvo-  46.  the  beautiful  and  perfect  organization  of  the  different  parts 

of  the  animal  body,  we  are  impressed  with  the  most  profound 
admiration  when  examining  the  mechanism  of  the  hand. 
The  organ  of  touch  and  prehension,  perfoiining  functions  the 
most  opposite ;  those  demanding  great  force,  and  those  re- 
quiring the  greatest  delicacy.  To  enable  it  to  fulfil  at  the 
same  time  functions  so  different,  great  solidity  and  great  mo- 
bility were  essential ;  and  to  secure  these  conditions,  it  was 
necessary  that  it  should  be  formed  of  a  great  number  of 
bones.  It  is  composed  of  twenty-seven  bones,  exclusive  of 
the  sesamoid  bones.  The  hand  exists  only  in  man  and  in 
the  ape  ;  and  its  importance  is  so  great,  that  it  has  been  con- 
sidered by  naturalists  as  establishing  a  fundamental  charac- 
ter of  the  species.  Man  alone  constitutes  the  class  of  bima- 
na ;  the  apes  form  the  class  quadrumana :  but  in  the  hand 
of  the  ape,  compared  with  that  of  man,  we  find  great  infe- 
riority. Let  us,  then,  study  with  the  attention  it  merits  this 
chef-d'auvre  of  mechanism,  which  some  of  the  philosophers 
of  antiquity  regarded  as  the  distinctive  character  of  man, 
and  even  as  the  source  of  his  intellectual  superiority. 
"Fae  hand,  considered  as  part  of  the  skeleton,  is  composed  of  five  series  of  small  col- 
umns. Each  series  consists  of  four  pieces,  excepting  the  outer  one,  which  has  three 
only.  The  five  series  of  colmnns  converge  so  as  to  unite  with  a  bony  mass,  composed 
of  eight  bones  (a  to  i)  articulated  together,  and  forming  by  their  junction  the  base  of  the 
hand  or  the  wrist.  This  bony  mass  is  called  the  carpus.  The  five  columns  {k  k),  next 
the  carpus,  have  received  the  name  of  metacarpal  bones ;  by  their  union  they  form  the 
metacarpus,  which  corresponds  with  the  palm  of  the  hand :  lastly,  the  columns  which 
succeed  to  the  metacarpus  form  appendages  which  are  entirely  isolated  and  independent 
of  each  other ;  these  are  the  fingers,  which  are  distinguished  by  numerical  names  of 
first,  second,  third,  fourth,  and  fifth,  counting  from  without  inward,  the  hand  being  su- 
pine, and  the  palm  turned  forward ;  they  are  also  known  by  the  following  appellations  : 
thumb,  index  or  indicator,  middle,  ring,  and  auricular  or  little  finger.  Each  finger  is  composed 
of  three  small  bones,  called  phalanges  {I  m  n),  distinguished  also  successively,  from  above 
downward,  by  the  numerical  names  of  first,  second,  and  third.  The  third  bears  also  the 
name  of  ungual,  because  it  supports  the  nail ;  the  thumb  has  only  two  phalanges  {I  n) ; 
it  is  also  distinguished  from  the  other  fingers,  by  being  on  a  plane  anterior  to  them. 

The  form  of  the  hand  leads  us  to  consider  separately  a  dorsal,  convex  surface,  the 
haah  of  the  hand  ;  an  anterior  or  palmar  surface,  the  palm  {fig.  46) ;  an  external  or  radial 
edge  {a  n),  formed  by  the  thumb  ;  an  internal  or  ulnar  edge  (c  n),  formed  by  the  little 
finger  ;  a  superior,  carpal,  or  anti-brachial  extremity ;  and  an  inferior  or  digital  extrem  • 
ity,  composed  by  the  ends  of  the  fingers,  which,  from  their  unequal  length,  form  a  curve 
wifcli  the  convexity  downward. 

The  natural  attitude  of  the  hand  is  that  of  pronation,  i.  e.,  the  attitude  in  which  it  is 
placed  when  the  bones  of  the  forearm,  instead  of  being  parallel  as  in  supination,  are 
crossed  in.  puch  a  manner  that  the  lower  part  of  the  radius  is  in  front  of  the  ulna.    The 

*  In.the  descriptiqa  of  the  muscles,  we  shall  point  out  the  tendon  which  occupies  each  of  there  primitive 
and  secondary  grooves.  All  enumerations  of  this  kind,  the  advantages  of  which  we  do  not  dispute,  when  the 
bones  and  muscles  are  already  known,  will  find  a  place  in  the  table  at  the  end  of  the  part  devoted  to  myology. 
We  have  noticed  liere  the  muscular  insertions,  because,  instead  of  burdening  the  memory,  they  are  useful  in 
fixing  the  attention  uppn  tie  objects  described. 


THE    CARPUS.  83 

hand  is  in  this  position  when  laying  hold  of  anything,  or  exercising  ihe  sense  of  touch 
It  is  only  for  the  convenience  of  description  that  we  shall  suppose  the  hand  to  be  in  the 
state  of  supination,  and  the  palm  turned  forward.    We  shall  be  obliged  to  return  to  pro- 
nation, when  we  draw  a  parallel  between  the  hand  and  the  foot. 
The  axis  of  the  hand  is  ahnost  the  same  as  that  of  the  fore2irm. 

The  Carpus  {a  to  f,  Jig.  46.) 

The  carpus  (from  Kapirdc,  wrist,  Kup-KSLv,  to  lay  hold  of)  constitutes  the  bony  structure 
of  the  wrist ;  it  is  of  an  oblong  form,  and  almost  elliptical  transversely.  The  anterior 
surface  {fig.  46)  is  concave,  and  forms  a  deep  groove,  in  which  the  tendons  of  the  flexor 
muscles  are  lodged.  The  posterior  surface  is  convex,  and  in  contact  with  the  extensor 
tendons.  They  are  both  traversed  by  waved  lines,  which  indicate  the  numerous  artic- 
ulations of  the  component  bones.  The  upper  border  is  convex,  and  articulates  with  the 
radius  and  ulna ;  the  lower  is  irregular  and  sinuous,  and  articulates  with  the  metacarpal 
hones. 

At  each  of  the  two  extremities  of  the  ellipse  represented  by  the  carpus,  we  observe 
two  eminences,  which  form  a  projection  on  the  anterior  aspect,  and  contribute  to  aug- 
ment the  depth  of  the  groove  which  it  forms.  The  two  which  occupy  the  outer  edge  of 
the  wrist  are  much  smaller  than  those  which  are  situated  on  its  inner  border. 

The  structure  of  the  carpus  is  remarkable  in  this  respect ;  that  in  proportion  to  its 
size,  it  presents  in  a  given  space  a  much  greater  number  of  bones  than  any  other  part 
of  the  skeleton.  It  consists,  in  fact,  of  eight  bones,  and  is  scarcely  one  inch  in  height, 
and  two  inches  and  a  half  in  breadth.  These  eight  bones  are  arranged  in  two  series,  or 
rows  ;  an  upper  proximal  or  anti-hrachial  {ah  c  d),  and  a  lotcer  distal  or  metacarpal  {e  i  g  f). 
Each  of  these  ranges  is  composed  of  four  bones  ;  counting  from  the  external  or  radial 
edge  towards  the  internal  or  ulnar,  they  are,  in  the  first  row,  the  scaphoid  {a),  the  semi- 
lunar (i),  the  cuneiform  (c),  (or  pyramidal),  and  the  pisiform  {d) ;  in  the  second  row,  tra- 
pezium (e),  the  trapezoid  {i),  the  os  magnum  (g),  and  the  unciforme  (/). 

I  shall  not  occupy  time  in  describing  successively  the  six  surfaces  on  each  of  these 
bones.  By  simply  explaining  the  law  which  regulates  their  configuration,  I  shall  have 
the  double  advantage  of  avoiding  prolixity,  and  of  enabhng  the  student  to  understand 
more  correctly  both  their  forms  and  relations. 

Bones  of  the  first  or  Anti-brachial  Range. 

What  I  have  just  said  of  these  bones  does  not  apply  to  the  pisiform,  which  is  distin- 
guished from  all  the  others  by  particular  characters,  and  merits  a  special  notice.  With 
regard  to  the  rest,*  viz.,  the  scaphoid  {a),  the  semilunar  {h),  and  the  cuneiform  (c),  it  may 
be  remarked,  1.  That  they  articulate  by  their  upper  surfaces  with  the  forearm,  forming 
a  sort  of  interrupted  condyle,  i.  e.,  one  consisting  of  several  pieces,  which  is  received 
into  the  cavity  formed  by  the  lower  end  of  the  radius  and  ulna.  Each  of  the  bones  con- 
tributes to  form  this  condyle,  by  means  of  a  convex  surface  ;  consequently,  the  superior 
surface  of  the  bones  of  the  first  rank  is  articular  and  convex.  2.  They  articulate  by  their 
lower  surfaces  with  the  bones  of  the  second  rank,  which  on  the  inside  oppose  to  them  a 
large  head  formed  by  the  os  magnum  and  unciform,  and  on  the  outside  a  shallow  con- 
cavity, which  corresponds  to  the  trapezium  and  the  trapezoid.  In  accordance  with  this, 
the  lower  surface  of  the  first  row  presents  on  the  one  hand  a  concavity,  which  receives 
the  head,  and  on  the  other  a  convexity,  which  corresponds  to  the  cavity. 

Three  surfaces,  belonging  to  the  scaphoid,  the  semilunar,  and  the  cuneiform,  unite  to 
form  the  cavity,  which  receives  the  head  belonging  to  the  second  row.  There  is,  there- 
fore, a  broken  cavity,  i.  e.,  one  formed  of  several  pieces.  The  scaphoid  being  the  largest 
of  the  bones  of  the  first  row,  and  corresponding  by  itself  to  the  most  convex  part  of  the 
head  of  the  second  row,  is  more  deeply  excavated  than  the  two  other  bones  ;  this  has 
given  it  the  form  of  a  boat,  whence  the  name  of  scaphoid  (<7«a0^,  a  boat).  The  semilu- 
nar, which  corresponds  to  the  summit  of  the  head,  presents  from  before  backward  a  con- 
cavity, which  has  given  it  its  name  ;  the  cuneiform,  on  the  contrary,  corresponds  to  the 
least  convex  part  of  the  articular  head,  and  has  an  almost  plane  surface.  » 

One  bone  only,  the  scaphoid,  answers  to  the  concavity  formed  by  the  trapezium  and 
trapezoides,  and  it  accordingly  presents  a  convex  surface  at  the  point  of  union.  There- 
fore the  lower  surfaces  of  the  bones  of  the  first  row  are  concave,  and  the  lower  surface  of  the 
scaphoid  is  partly  concave  and  partly  convex. 

3.  The  bones  of  the  first  row  of  the  carpus  unite  with  each  other  by  plane  surfaces ; 
those  of  the  scaphoid  and  semilunar,  which  join,  are  very  small ;  the  contiguous  surfa- 
ces of  the  semilunar  and  the  cuneiform  are  much  larger. 

The  semilunar  and  the  cuneiform,  which  occupy  the  middle  of  the  row,  articulate  not 
only  with  each  other,  but  also  with  the  scaphoid  and  the  pisiform ;  and  each,  therefore,  has 
two  lateral  surfaces,  so  that  the  two  middle  bones  of  the  row  have  four  artitular  facettes. 

*  It  is  neces.sary,  in  order  to  follow  this  description,  and  obtain  from  it  all  the  advantage  wkich  it  can  afford, 
to  study  at  the  same  time  an  articulated  carpus,  especially  one  in  which  the  joints  are  exposed  behind,  soma 
ligaments  remaining  in  front. 


"^ 


OSTEOLOGY. 


The  scaphoid,  which  is  the  outer  bone  of  the  first  row,  articulates  internally  witn  th(6 
semilunar,  but  externally  it  has  a  projecting  process,  which  may  be  easily  felt  under  the 
skin,  and  which  increases  the  depth  of  the  anterior  groove  of  the  carpus.  This  eminence 
constitutes  the  external  superior  process  of  the  carpus.  4.  The  bones  of  the  first  row 
forming  part  of  the  concavity  in  front,  and  of  the  convexity  behind,  have  their  anterior 
surfaces  much  smaller  than  their  posterior  ;  both  are  rough,  and  serve  for  the  insertion 
of  ligaments. 

The  pisiform  (d)  is  not  in  the  same  rank,  and  has  only  one  articular  surface,  which 
unites  with  the  corresponding  surface  on  the  cuneiform.  The  whole  of  the  rest  of  its 
surface  is  intended  for  the  insertion  of  ligaments  and  tendons.  Its  name  is  derived  from 
its  irregularly  rounded  form.  It  is  placed  on  a  plane  anterior  to  that  of  the  other  bones  of 
the  first  row,  and  forms  the  internal  superior  process,  which  is  the  most  prominent  and 
the  most  superficial  of  aU  the  processes  of  the  carpus.  The  pisiform  receives  above  the 
insertion  of  the  flexor  carpi  ulnari^  and  below  allows  of  the  origin  of  the  abductor  minimi 
digiti.     It  might  with  propriety  be  considered  as  a  sesamoid  bone. 

Bones  of  the  Second  or  Metacarpal  Row. 

The  bones  of  the  second  row  are  much  larger  than  those  of  the  first ;  they  form,  in 
fact,  the  support  of  the  metacarpus.  In  the  first  row,  the  outer  bone,  namely,  the  sca- 
phoid, is  the  larger ;  in  the  second,  the  two  inner  bones,  viz.,  the  os  magnum  (g)  and 
unciform  (f). 

Superior  Surfaces. — We  have  already  stated,  that  the  surface  of  the  second  row,  which 
articulates  with  the  first,  presents  a  head  and  a  cavity.  The  head  is  formed  almost  en- 
tirely by  a  spheroidal  eminence,  named  head  of  the  os  magnum ;  this  is  supported  by  a 
(Constricted  portion,  or  neck,  below  which  is  the  body,  the  largest  part  of  the  bone  ;  this 
head  of  the  os  magnum  is  truncated  at  its  inner  part,  and  appears  to  be  completed  by  a 
portion  of  the  os  unciforme.  The  concavity  presented  by  the  bones  of  the  second  row 
is  constituted  by  two  bones,  the  trapezium  (c),  situated  on  the  outside  of  the  carpus,  and 
the  trapezoid  (i),  placed  between  the  trapezium  and  os  magnum. 

The  inferior  surfaces  correspond  to  the  bones  of  the  metacarpus.  Taken  together, 
these  surfaces  form  a  sinuous  and  angular  line,  which  by  itself  would  seem  to  prove  the 
impossibility  of  dislocation  of  the  metacarpus.  The  trapezium  supports  the  first  meta- 
carpal bone  ;  the  trapezoid  the  second  ;  the  os  magnum  the  third  ;  and  the  os  unciforme 
the  fourth  and  fifth  metacarpal  bones. 

The  posterior  surfaces  of  the  bones  of  the  second  row  form  part  of  the  convexity  of  the 
carpus  ;  the  anterior  surfaces  are  narrower,  and  correspond  with  its  concavity.  There 
is  a  process  on  the  anterior  aspect  at  each  extremity  of  the  second  row ;  the  internal  be- 
longs to  the  unciform  bone,  and  resembles  a  hook,  the  concavity  of  which  looks  outward, 
and  corresponds  with  the  flexor  tendons ;  the  external  belongs  to  the  trapezium,  and 
forms  a  much  less  prominent  hook  than  that  of  the  unciform ;  on  its  inside  there  is  a 
deep  oblique  groove  for  the  passage  of  the  tendon  of  the  flexor  carpi  radialis,  and  it  forms 
the  external  inferior  process  of  the  carpus. 

Lateral  Surfaces. — The  bones  of  the  second  row  are  joined  together  by  broad  plane 
surfaces,  partly  articular  and  partly  non-articular.  The  two  middle  bones,  viz.,  the  tra- 
pezoid and  the  os  magnum,  have  each  two  lateral  articular  surfaces,  inasmuch  as  they 
are  articulated  with  each  other,  and  since  the  os  magnum  is  united  to  the  unciform,  and 
the  trapezoid  to  the  trapezium.  The  extreme  bones  of  this  row  have  only  one  side  ar- 
ticular. Each  of  the  middle  bones,  therefore,  has  four  articular  surfaces,  a  superior,  an  in- 
ferior, and  two  lateral ;  each  of  the  extreme  bones  a  superior,  an  inferior,  and  one  lateral 

Development  of  the  Carpal  Bones. 
All  the  bones  of  the  carpus,  without  exception,  are  developed  from  single  points.  The 
ossific  points  appear  very  slowly ;  all  the  bones  are  cartilaginous  at  birth.  Towards  the 
end  of  the  first  year,  the  cartilages  of  the  os  magnum  and  the  unciform  show  a  bony 
point  in  the  centre.  The  osseous  point  of  the  cuneiform  appears  from  the  third  to  the 
fourth  year ;  those  of  the  trapezium  and  semilunar,  from  the  fourth  to  the  fifth ;  and 
those  of  the  scaphoid  and  the  trapezoid,  from  the  eighth  to  the  ninth  year.  The  pisiform 
does  not  become  ossified  until  from  the  twelfth  to  the  fifteenth  year ;  in  fact,  it  is  the 
latest  to  ossify  of  all  the  bones  of  the  skeleton. 

The  Metacarpus  (k  k\  Jig.  46). 

The  five  bony  columns  which  rest  upon  the  carpus  form  the  metacarpus ;  they  are  long 
bones  placed  parallel  to  each  other,  and  constructed  on  the  same  model,  with  very  slight 
differences.  Together  they  form  a  sort  of  square  grating,  the  intervals  of  which  are 
larger,  on  account  of  the  disproportion  existing  between  the  size  of  the  middle  part  and 
the  ends  of  these  bones.  These  intervals  are  denominated  interosseous  spaces,  and  are 
occupied  by  muscles. 

The  metacarpal  bones  are  five  in  number,  distinguished  by  the  names  of  first,  second, 
&c.     They  are  not  perfectly  uniform,  either  in  situation,  length,  or  shape.     The  meta- 


GENERAL  CHARACTERS  OF  THE  METACARPAL  BONES.        86 

carpal  bone  of  the  thumb,  for  instance,  is  situated  upon  a  plane  anterior  to  that  which 
the  others  occupy  ;  instead  of  being  parallel,  it  is  directed  obliquely  outward  and  do\vn- 
ward,  and  hence  the  interosseous  space  between  it  and  the  second  metacarpal  bone  is 
triangular. 

This  arrangement  is  connected  with  the  movement  of  opposition,  which  is  the  char- 
acteristic feature  of  the  hand.  The  metacarpus  presents  a  palmar  or  anterior  surface. 
concave  transversely,  and  slightly  so  from  above  downward,  which  corresponds  with  the 
falm.  of  the  hand ;  a  dorsal  convex  surface,  the  hack  of  the  hand ;  an  external  or  radial  edo-e, 
which  is  short,  obliquely  directed  outward  and  downward,  and  corresponds  to  the  thumb ; 
an  ulnar  edge,  short  and  straight,  which  corresponds  with  the  little  finger ;  a  superior'or 
carpal  extremity,  which  presents  a  very  sinuous  articular  line,  to  fit  the  opposite  surface  of 
the  carpus  ;  and  an  inferior  or  digital  extremity,  formed  by  five  heads,  or,  rather,  condyles, 
flattened  on  the  sides,  and  intended  to  articulate  with  the  corresponding  fingers :  this 
lower  d^tremity  forms  a  broken  articular  line  ;  it  is  curved,  with  the  convexity  doAvn- 
ward,  and  the  first  metacarpal  bone  does  not  appear  to  belong  to  it. 

General  Characters  of  the  Metacarpal  Bones. 

The  metacarpal  bones  belong  to  the  class  of  long  bones,  having  the  same  form  and 
structure  ;  each  consists  of  a  hody  and  two  extremities. 

The  hody  is  prismatic  and  triangular,  and  slightly  curved,  so  as  to  present  a  concavity 
on  the  palmar,  and  a  convexity  on  the  dorsal  aspect.  Of  the  three  surfaces  of  the  body, 
two  are  lateral,  and  correspond  to  the  interosseous  spaces  ;  the  third  is  on  the  back  of 
the  hand,  and  is  covered  by  the  tendons  of  the  extensor  muscles.  Of  the  edges,  two  are 
lateral ;  the  third  is  anterior,  and  corresponds  with  the  palm  of  the  hand. 

The  upper  or  carpal  extremity  is  large,  and  has  five  surfaces,  an  anterior  and  a  poste- 
rior, for  ligamentous  insertions,  and  three  articular ;  of  the  three  articular  surfaces,  one 
is  at  the  end  of  the  bone,  and  unites  with  a  corresponding  surface  on  a  carpal  bone  ;  the 
two  others  occupy  the  sides  of  the  extremity,  and  unite  with  corresponding  surfaces  of 
the  adjoining  metacarpal  bones.  In  some  metacarpal  bones,  the  lateral  facettes  are 
double  on  each  side.  It  is  necessary  to  distinguish  such  of  these  lateral  facettes  as  are 
intended  to  unite  with  bones  of  the  carpus,  between  which  one  of  the  metacarpal  bones 
is,  as  it  were,  wedged,  from  those  which  are  exclusively  intended  for  the  articulation  of 
the  metacarpal  bones  with  each  other. 

The  lower  or  digital  extremity  resembles  a  head  flattened  on  the  sides,  or  a  condyle  ob- 
long from  before  backward,  with  an  articular  surface  of  greater  extent  on  the  palmar 
than  on  the  dorsal  aspect,  i.  c,  admitting  of  greater  flexion  than  extension ;  it  is  marked 
both  internally  and  externally  by  a  depression,  behind  which  is  a  rough  projection  for 
the  attachment  of  lateral  hgaments. 

Are  there  any  peculiar  characters  by  which  the  different  metacarpal  bones  may  be 
distinguished  1     This  question  we  shall  now  examine. 

Differential  Characters  of  the  Metacarpal  Bones. 

The  first  metacarpal  bone  (t)  is  distinguished  from  the  others  by  the  following  char- 
acters :  it  is  the  shortest  and  the  largest ;  its  body  is  flattened  in  front  and  behind 
like  the  phalanges ;  so  that  at  times  it  has  been  looked  upon  as  one  of  those  bones. 
We  shall  regard  it  as  belonging  to  the  metacarpus,  because  it  is  not  only  united  to  the 
other  metacarpal  bones  by  the  interosseous  muscles,  but  its  inferior  or  digital  extremity 
also  has  an  exact  resemblance.  At  the  same  time,  we  must  acknowledge  that  there  is 
a  circumstance  in  its  development  which  tends  to  establish  its  analogy  with  the  pha- 
fanges.  The  carpal  extremity  of  the  first  metacarpal  bone  has  a  particular  form ;  it  is 
concave  from  before  backward,  and  convex  transversely,  for  articulation  with  the  cor- 
responding surface  on  the  trapezium.  The  characteristic  marks,  then,  by  which  the  first 
metacarpal  bone  may  be  recognised,  are,  its  shortness,  its  greater  size,  the  antero-postenor 
flattening  of  the  hody,  the  upper  articular  surface  concave  and  convex  in  opposite  directions. 
and  the  absence  of  lateral  articular  facettes. 

There  are  many  distinguishing  characters  of  the  second,  third,  and  fourth  metacarpal 
bones.  I  shall  content  myself  with  saying,  that  the  second  and  third  are  known  by 
their  greater  length,  for  they  exceed  the  fourth  by  the  whole  of  their  lower  extremity ; 
they  are  also  about  a  third  larger,  and  heavier. 

The  third  metacarpal  bone  is  distinguished  from  the  second  by  its  greater  size,  and, 
accordingly,  it  gives  attachment  to  one  of  the  most  powerful  muscles  of  the  hand,  the 
adductor  pollicis  ;  it  is  also  known  by  having  two  lateral  facettes  on  its  upper  extremity, 
while  the  second  has  only  one. 

The  fifth  metacarpal  bone  (k)  is  the  shortest  of  all,  excepting  the  first,  from  which  it 
is  distinguished  by  its  smaller  size.  It  differs  from  the  fourth,  which  it  most  resembles, 
1.  By  its  shortness.  2.  By  the  presence  of  an  articular  facette  only  on  one  side  of  its 
carpal  extremity.  3.  By  the  existence  of  a  very  projecting  eminence  on  its  inner  side, 
for  the  insertion  of  the  extensor  carpi  ulnaris  muscle. 


m 


OSTEOLOGY. 


Connexions. — The  metacarpal  bones  articulate  with  each  other,  with  the  bones  of  the 
carpus,  and  with  the  first  phalanges  of  the  corresponding  fingers. 

Internal  Structure. — They  have  the  same  structure  as  other  long  bones :  their  extrem- 
ities are  cellular,  and  the  shafts  compact,  with  a  small  medullary  canal. 

Development. — Each  metacarpal  bone  is  developed  from  two  points ;  one  for  the  body 
and  superior  extremity,  and  one  for  the  lower  or  distal  extremity.  The  first  metacarpal 
bone,  which  in  many  respects  resembles  the  phalanges,  is  similar  also  in  its  mode  of 
development.  One  of  its  two  points  appears  in  the  shaft ;  the  other  in  the  upper  or 
carpal  extremity,  which  is  the  reverse  of  what  takes  place  in  the  other  bones  of  the 
same  denomination,  and  is  analogous  to  that  of  the  phjdanges.  The  ossific  point  of  the 
body  of  the  metacarpal  bone  appears  from  the  fortieth  to  the  fiftieth  day  of  fcetal  life. 
At  birth  the  body  is  almost  completely  ossified,  but  the  extremities  are  still  cartilaginous. 
The  bony  points  of  the  lower  ends  of  the  last  four  metacarpal  bones,  and  of  the  upper 
end  of  the  first,  do  not  make  their  appearance  until  the  third  or  fourth  year.  In  general, 
the  upper  ends  of  the  last  four  bones,  and  the  lower  end  of  the  first,  are  ossified  by  an 
extension  of  the  shaft  ;  but  I  have  occasionally  seen  separate  germs  for  each  of  these, 
so  that  every  metacarpal  bone  had  three  osseous  nodules.  The  union  of  the  lower  ex- 
tremities with  the  bodies  of  the  four  metacarpal  bones  does  not  take  place  until  the 
eighteenth  or  twentieth  year ;  and  the  same  is  the  case  with  the  ossific  point  of  the  up- 
per end  of  the  first  metacarpal  bone.  In  those  cases  where  the  lower  end  of  the  first 
metacarpal,  and  the  upper  ends  of  the  others,  are  formed  from  special  points,  their  union 
takes  place  at  a  much  earlier  period. 

The  Fingers  {I  m  n,  and  I'  n'yjig.  46). 

The  fingers  are  the  essential  organs  of  prehension,  and  for  this  purpose  have  a  length 
thickness,  and  mobility  that  are  very  remarkable,  when  we  compare  them  with  the  toes, 
which  represent  them  in  the  lower  extremity.  Each  finger  forms  a  pyramid,  composed 
of  three  columns  placed  upon  each  other  ;  the  base  of  the  pyramid  corresponds  to  the 
metacarpus,  and  there  are  two  enlargements  or  knots  at  the  places  where  the  columns 
(named  phalanges)  unite  together.  The  three  columns  which  compose  each  finger  suc- 
cessively decrease  in  size,  and  are  known  by  the  numerical  appellations  of  first,  second, 
and  third.  The  first,  which  articulates  with  the  metacarpus,  is  also  called  the  metacarpal 
phalanx  (Z  I') ;  the  second,  the  middle  phalanx  (m) ;  and  the  third,  which  supports  the  nail, 
the  ungual  phalanx  {n  n').  The  thumb  alone  has  only  two  phalanges,  an  ixngual  and  a 
metacarpal.  Chaussier  has  named  the  phalanges  phalange,  phalangine,  and  phalangette, 
counting  from  the  base  to  the  ends  of  the  fingers.  These  denominations  he  has  found 
very  serviceable  in  the  methodical  designation  of  the  muscles  of  the  fingers. 

The  First  Phalanx  {I  I'). 

The  first  phalanx  belongs  to  the  class  of  long  bones,  and  presents  to  our  notice,  1.  A 
body  resembling  a  half  cylinder,  cut  along  its  axis,  and  slightly  curved  upon  itself,  so  as 
to  present  a  concavity  in  front ;  the  dorsal  surface  is  cylindrical,  and  covered  by  the 
tendons  of  the  extensor  muscles  ;  the  anterior  surface  is  slightly  channelled  for  the  par- 
tial lodgment  of  the  tendons  of  the  flexor  muscles  ;  its  edges  are  sharp,  and  give  attach 
ment  to  a  tendinous  sheath,  which  converts  the  channel  above  mentioned  into  an  osteo- 
fibrous  canal  for  the  flexor  tendons  of  the  fingers.  2.  An  upper  or  mxtacarpal  end,  trans 
versely  oblong,  and  presenting  a  small  glenoid  cavity  for  the  head  of  the  corresponding 
metacarpal  bone.     3.  A  lower  end,  forming  an  articular  pulley. 

Such  are  the  general  characters  of  the  first  phalanx,  but  they  are  modified  in  each 
finger.  Thus,  the  phalanx  of  the  middle  finger  is  the  longest ;  those  of  the  index  and 
ring  finger  come  next.  The  first  phalanx  of  the  thiunb  is  the  largest  in  proportion  to  its 
length ;  the  first  phalanx  of  the  little  finger  is  the  most  slender ;  it  is  also  the  shortest, 
excepting  that  of  the  thumb. 

The  Second  Phalanx  (m). 

The  second  phalanx  differs  from  the  first  by  its  smaller  size  and  the  shape  of  its  up 
per  end,  which  forms  two  concave  articular  facettes,  separated  from  each  other  by  a 
projecting  line,  which  runs  from  before  backward ;  these  are  fitted  to  the  trochlea  on  the 
lower  end  of  the  first  phalanx.  The  edges  of  this  phalanx  are  thick  and  rough  above, 
where  they  give  insertion  to  the  tendon  of  the  superficial  flexor  of  the  fingers. 

The  thumb  has  no  second  phalanx. 

The  Third  Phalanx  (n  «'). 
This  bone,  to  which  so  much  importance  has  been  attached  in  natural  history,*  sup- 
ports the  horny  part  with  which  the  ends  of  the  digits  in  animals  are  armed,  and  the 
nails  in  man.    It  is  shaped  thus :  the  upper  end  is  transversely  oblong,  exactly  resem* 

*  See  the  interesting  memoir  of  M.  Dum6ril,  entitled  Dissertation  sur  la  demiire  Phalange  dans  Us  Mam 
ndfe.res  ;  the  ungual  phalanx  presenting  different  forms,  suited  to  the  difterent  instincts  of  the  animal.  Thi» 
is  BO  remarkable,  that,  from  its  examination,  the  family  to  which  the  animal  belonged  may  be  ascertained. 


THE   PELVIS.  gP 

bling  the  upper  end  of  the  second  phalanx ;  from  this  part  it  contracts  like  a  cone  ;  sifter- 
ward  it  becomes  much  enlarged  and  flattened  from  before  backward,  and  ends  with  the 
shape  of  a  horse-shoe,  rough  in  front,  where  it  supports  the  pulp  of  the  finger,  smooth 
behind,  and  indented  on  the  edges.  The  ungual  phalanx  of  the  thumb  is  much  larger 
than  that  of  the  other  fingers  ;  that  of  the  middle  one  is  the  next  in  size ;  those  of  the 
index  and  ring  finger  are  almost  equal,  and  that  of  the  little  finger  is  the  smallest.  It  is 
very  difficult  to  distinguish  the  phalanges  of  the  right  from  those  of  the  left  hand. 

Development  of  the  Phalanges. 
The  phalanges  are  developed  from  two  points :  one  for  the  body  and  lower  end,  and 
one  for  the  upper  end.  This  mode  of  development  is  common  to  the  first,  second,  and 
third  phalanges.  The  osseous  point  of  the  body  appears  successively  in  the  first,  sec- 
ond, and  third  phalanges,  from  the  fortieth  to  the  fiftieth  day.  The  order  of  succession 
is  not  subjected  to  any  certain  rules.  Bony  points  are  found  at  the  same  time  in  the 
ungual  and  metacarpal  phalanges,  and  prior  to  those  of  the  middle  phalanges.  The  os- 
sific  points  of  the  upper  ends  of  the  phalanges  appear  successively  in  the  first,  second, 
and  third  phalanges  some  time  after  birth,  from  the  third  to  the  seventh  year.  The 
epiphysary  point  of  the  third  phalanx  is  generally  developed  before  that  of  the  second. 
The  epiphyses  do  not  join  the  bodies  of  the  bones  until  from  the  eighteenth  to  the  twen- 
tieth year. 

General  Development  of  the  Superior  Extremity. 

The  thoracic  limb  in  the  foetus  and  the  infant  is  remarkable  for  its  dimensions,  which 
are  proportionally  much  greater  than  in  the  adult.  This  early  development  and  size  are 
particularly  evident  when  compared  with  the  slow  development  of  the  lower  limb  ;  the 
resulting  disproportion  is  in  an  inverse  ratio  of  the  age,  that  is,  it  is  greatest  in  early  life. 
The  thoracic  limb  of  the  foetus  differs  from  that  of  the  adult  in  many  other  respects  be- 
sides dimensions.  Thus,  the  two  extremities  of  the  humerus  are  proportionally  much 
larger,  and  altogether  cartilaginous,  though  the  difference  does  not  appear  to  me  so  great 
as  has  been  imagined.  The  lower  end  of  the  bone  is  especially  remarkable  for  the  size 
of  the  small  head,  which  forms  a  very  marked  protuberance  in  front,  and  projects  con- 
siderably beyond  the  pulley  or  trochlea.  In  the  forearm,  the  upper  end  of  the  radius  is 
situated  much  farther  forward  than  in  the  adult,  which  agrees  with  the  position  of  the 
small  head  of  the  humerus.  This  circumstance  merits  careful  notice,  because  it  is  one 
of  the  predisposing  causes  of  dislocation  of  the  head  of  the  radius  forward,  the  ligament 
which  keeps  it  back  being  scarcely  able  to  overcome  its  tendency  in  that  direction.  For 
the  same  reason,  displacements  of  the  head  of  the  radius  are  much  more  frequent  in  the 
infant  than  in  the  adult. 

The  carpus,  almost  completely  unossified  at  birth,  is  composed  of  the  same  number 
of  cartilages  as  there  are  bones  afterward.  The  metacarpus,  on  the  contrary,  is  ossified 
long  before  birth,  but  this  rapid  development,  common  to  the  whole  thoracic  extremity, 
is  most  remarkable  in  the  phalanges. 

Bichat  appears  to  me  to  have  greatly  exaggerated  the  changes  which  take  place  in 
these  bones  during  the  progress  of  age.  I  am  certain  that  the  torsion  of  the  humerus, 
and  the  curvatures  of  the  radius  and  ulna,  and  also  the  interosseous  space,  exist  equally 
in  the  new-born  infant  as  in  the  adult,  and  in  almost  the  same  proportions. 


THE  INFERIOR  OR  ABDOMINAL  EXTREMITIES. 

The  Haunch. — Os  Coxce. — The  Pelvis. — Development. — Femur. — Patella. — Tibia. — Fibula. 
— The  Foot. — The  Tarsus  and  Tarsal  Bones. — The  Metatarsus  and  Metatarsal  Bones. — 
The  Toes. — Development  of  the  Lower  Extremities. — Comparison  of  the  Upper  and  Lower 
Extremities. — Os  Hyoides. 

The  inferior  or  abdominal  extremity  is  divided,  like  the  superior,  into  four  parts,  viz., 
the  haunch,  the  thigh,  the  leg,  and  the  foot. 

Of  the  Pelvis. 
We  have  seen  bony  arches  growing  out  from  the  sides  of  the  dorsal  portion  of  the  ver- 
tebral column,  to  form  the  thorax.  In  the  same  way  there  grows  out  from  the  sacral 
portion  of  the  column  two  large  bones,  which  form  the  walls  of  the  pelvic  cavity.  These 
are  the  ossa  innominata  or  haunch  bones.  The  pelvis  forms  an  appendix  to  the  abdominal 
cavity,  and  lodges  and  protects  a  number  of  important  organs,  viz.,  a  portion  of  the  or- 
gans of  digestion  and  of  the  urinary  apparatus,  and  the  whole  of  the  internal  organs  of 
generation,  together  with  important  vessels  and  nerves.  The  pelvis  transmits  to  the 
inferior  extremities  the  weight  it  receives  from  the  vertebral  column.  It  is  formed  by 
four  bones,  two  of  which  placed  behind  on  the  median  line,  the  sacrum  and  the  coccyx, 
we  have  already  described ;  the  two  placed  on  the  sides,  and  extending  forward  to  be 
united  on  the  median  line  before,  the  ossa  innominata,  we  shall  now  examine. 


88 


OSTEOLOGY. 


The  Os  Coxce,  or  Os  Innominatum  {figs.  47  and  48). 
The  haunch  hone,  called  also  os  coxce,  from  coxa,  the  haunch,  occupies  the  lateral  and 
anterior  parts  of  the  pelvis.  It  is  the  largest  of  all  the  broad  bones  of  the  skeleton.  It 
is  asymmetrical,  very  irregular  in  its  figure,  and  twisted  upon  itself,  so  that  it  appears  to 
be  composed  of  two  portions  ;  one  superior,  triangular,  shaped  like  a  wing,  and  flattened 
from  without  inward ;  the  other  inferior,  and  flattened  from  before  backward.  These 
two  parts  are  united  by  a  contracted  portion.  On  this  bone  we  have  for  consideration 
an  external  or  femoral  surface,  which  corresponds  with  the  thigh,  an  internal  or  pehic 
surface,  and  a  circumference. 

On  the  femoral  surface  (fig.  47)  we  observe  the  following  parts  :  On  the  contracted 
Fig.  47.  portion,  which  unites  the  upper  and  the  lower 

half  of  the  os  coxae,  is  the  cotyloid  cavity  {a.  Jigs. 
47,  48)  (from  Korvlrj,  a  cup),  or  acetabulum, 
which  receives  the  head  of  the  femur.  This  is 
of  a  hemispherical  shape,  and  is  the  deepest  of 
\v  all  the  articular  cavities ;  it  looks  obliquely 
downward,  outward,  and  a  little  forward,  and 
has  a  considerable  depression  (b,  fig.  47)  at  the 
bottom,  on  its  inner  aspect.  The  margin  (c)  of 
this  cavity  is  sharp  and  sinuous,  and  presents 
three  notches,  or,  rather,  one  notch  and  two  slight 
depressions,  one  of  which  is  superior,  and  the 
other  inferior,  and  somewhat  external.  The 
notch  (d)  is  situated  below  and  on  the  inside  ;  it 
is  very  deep,  and  converted  into  a  foramen  by  a 
ligament,  and  gives  passage  to  the  vessels  which 
penetrate  into  the  cotyloid  cavity.  Above  and 
below  the  acetabulum  are  two  horizontal 
grooves  ;  the  upper  one  is  superficial,  and  gives  attachment  to  a  fibrous  expansion,  one 
of  the  origins  of  the  rectus  femoris ;  the  lower  is  deeper,  and  gives  passage  to  the  tendon 
of  the  obturator  externus.  Above  the  cotyloid  cavity,  the  os  coxse  presents  a  broad  tri- 
angular surface,  improperly  called  external  iliac  fossa  (c).  On  it  we  observe,  proceeding 
from  behind  forward,  1.  A  convexity :  2.  A  concavity,  occupying  about  two  thirds  of  the 
fossa,  and  on  which  the  principal  nutritious  foramina  are  situated  :  3.  A  second  convex- 
ity :  4.  A  slight  concavity. 

The  external  iliac  fossa  is  traversed  by  two  curved  lines  for  muscular  insertions  ;  one 
posterior,  called  the  superior  semicircular  line  (/) ;  the  other  anterior,  and  much  more 
extensive,  the  inferior  semicircular  line  (g).  All  the  whole  surface  behind  the  former 
gives  attachment  to  the  gluteus  maximus  :  the  portion  comprised  between  the  two  lines 
gives  attachment  to  the  gluteus  medius. 

Below  the  acetabulum  we  observe  proceeding  from  without  inward,  1.  The  obturator 
foramen  (h,  figs.  47  and  48),  improperly  so  called  ;  it  is  placed  more  internally  than  the 
acetabulum,  and  has  an  oval  form  in  the  male  (hence  its  name,  foramen  ovale) :  in  the 
female  it  is  smaller,  and  triangular.  Its  longest  diameter  is  vertical,  and  it  slopes  a  lit- 
tle downward  and  outward.  At  its  upper  part  is  the  obturator  groove  {i,fig.  48),  directed 
obliquely  from  behind  forward  and  inward.  It  gives  passage  to  vessels  and  nerves,  and 
has  two  lips :  an  anterior,  which  is  continuous  with  the  outer  half  of  the  circumference 
of  the  foramen  ;  and  a  posterior,  which  is  continuous  with  the  internal  half;  for  the  two 
halves  of  the  circumference  of  the  obturator  foramen,  instead  of  being  united  in  front, 
pass  in  different  directions,  the  internal  backward,  and  the  external  forward,  leaving  be- 
tween them  an  interval  which  constitutes  the  groove.  2.  On  the  inside  of  the  obturator 
foramen  is  a  square  surface  (k,  figs.  47  and  48),  broader  above  than  below,  oblong  in  a 
vertical  direction,  and  rough  for  the  insertion  of  several  muscles  of  the  thigh.  This  is 
continuous  below  with  another  surface  (/,  fig.  47),  broader  inferiorly  than  above,  which 
extends  obliquely  downward  and  outward,  then  curves  upward,  and  terminates  below 
the  cotyloid  cavity.  This  surface,  which  bounds  the  obturator  foramen  below,  is  intend- 
ed for  muscular  insertions. 

The  internal  or  pelvic  surface  (fig.  48)  of  the  os  coxse  is  concave.  It  is  divided  into 
two  parts  :  a  superior,  w^hich  looks  upward,  and  an  inferior,  which  looks  backward,  by  a 
prominent  horizontal  ridge  (m  n  o,  fig.  48),  which  forms  the  lower  boundary  of  the  in- 
ternal iliac  fossa.  Above  this  ridge,  which  we  shall  afterward  see  forms  the  greatest 
part  of  the  inlet  of  the  pelvis,  we  find,  proceeding  from  behind  forward,  1.  A  very  prom- 
inent and  rough  tuberosity  (r),  intended  for  several  ligamentous  attachments.  2.  An  ir- 
regular eirticuiar  surface,  broader  above  than  below,  and  called  the  auricular  surface  (s) 
of  the  OS  coxae,  from  a  supposed  resemblance  to  the  concha  of  the  ear ;  it  looks  down- 
ward and  inward,  and  articulates  with  a  corresponding  surface  on  the  sacrum.  3.  More 
anteriorly,  and  on  a  higher  plane,  a  deep  and  regular  excavation,  correctly  denominated 
tne  internal  iliac  fossa  (t).     This  fossa,  which  is  broad  and  smooth,  is  occupied  by  the 


THE   PELVIS.  89 

iliacus  muscle.    At  its  lower  part  there  is  a  nutritious  foramen,  which  does  not  corre- 
spond with  that  on  the  outside  of  the  bone. 

Below  the  horizontal  ridge,  which  divides  the  internal  surface  of  the  os  coxa;  into  two 
halves,  we  observe,  proceeding  from  without  inward,  and  from  behind  forward,  l.-A 
smooth  quadrilateral  surface,  broader  above  than  below,  slightly  concave,  and  sloping 
from  above  downward,  inward,  and  forward  :  the  front  of  this  surface  corresponds  to  the 
depression  at  the  bottom  of  the  cotyloid  cavity.  2.  Behind  this  surface,  a  large  notch, 
which  will  be  noticed  when  describing  the  circumference  of  the  bone.  3.  In  front,  the 
inner  opening  of  the  obturator  foramen,  at  the  upper  part  of  which  is  the  commence- 
ment of  the  groove  already  described.  4.  Inside  the  foramen,  a  quadrilateral  surface, 
narrower  below  than  above,  where  it  forms  a  plane,  sloping  downward  and  backward, 
which  corresponds  to  the  bladder.     5.  Below  the  same  foramen,  a  smooth  surface. 

The  circumference  of  the  os  coxae  is  very  irregular,  and  consists  of  a  series  of  alter- 
nate projections  and  notches.  We  shall  describe  four  borders  in  this  circumference ;  a 
superior,  an  inferior,  an  anterior,  and  a  posterior. 

The  superior  border  or  crest  of  the  ilium  {u  v,  figs.  47  and  48)  is  curved  like  the  italic 
letter  iS ;  it  is  directed  from  before  backward,  is  rough,  thick,  and  convex ;  we  shall  de- 
scribe it  as  having  two  lips  and  an  interstice,  that  Ave  may  be  able  to  point  out  with 
precision  the  numerous  muscular  insertions  of  which  it  is  the  seat.  It  is  not  equally 
thick  in  its  whole  extent ;  the  anterior  extremity  is  thick,  it  is  then  contracted  a  little ; 
about  two  inches  behind  this  extremity  it  is  considerably  enlarged ;  and  still  more  pos- 
teriorly there  is  a  second  enlargement  even  greater  than  the  former.  The  inferior  bar- 
ber (w  X  y,  fig.  47),  which  looks  inward,  is  the  shortest ;  it  commences  at  the  most  slo- 
ping part  of  the  os  coxae  by  a  large  rough  tuberosity,  called  tuberosity  of  the  ischium  (w  x), 
which  gives  attachment  to  almost  all  the  muscles  on  the  back  of  the  thigh  ;  the  weight 
of  the  body  rests  upon  it  in  the  sitting  posture.  Proceeding  from  this  tuberosity  towards 
the  inner  part  of  the  os  coxa3  (x  y),  tlie  lower  border  becomes  flexuous,  irregular,  and 
shghtly  twisted  upon  itself;  it  passes  obliquely  inward  and  upward,  and  contributes  to 
form  the  pubic  arch  (z  y  x,  fig.  48).  Above  this  oblique  portion  the  border  presents  a 
vertical  elliptic  surface,  which  unites  with  the  corresponding  surface  on  the  opposite 
bone,  and  forms  the  symphysis  pubis  (y  y",  figs.  47,  48).  The  lower  border  of  tlie  os  coxae 
consists,  therefore,  of  two  portions  ;  an  oblique,  which  forms  part  of  the  arch,  and  a  ver- 
tical, which  forms  part  of  the  symphysis. 

The  anterior  border  (u  y',  figs.  47,  48)  commences  at  the  anterior  extremity  of  the  crest 
of  the  ilium  by  an  eminence  for  muscular  insertion,  which  can  be  always  easily  felt  un- 
der the  skin  ;  it  is  the  anterior  superior  spinous  process  of  the  ilium  (m).  Below  is  a  notch 
(m  u'),  which  separates  this  process  from  another  eminence  for  the  insertion  of  the  rec- 
tus femoris  ;  it  is  caUed  anterior  inferior  spinous  process  of  the  ilium  {u').  Below  this  last 
process  is  a  notch  or  angular  groove  {uf  n),  over  which  the  iliac  muscle  glides :  on  this 
situation  the  anterior  border  changes  its  direction,  and,  from  being  vertical,  becomes 
horizontal.  The  horizontal  portion  of  the  anterior  border  presents  then  a  smooth  con- 
cave surface  inclined  forward,  and  shaped  like  a  triangle,  with  the  base  outward.  This 
triangular  surface,  which  is  covered  by  the  pectineus  muscle,  presents,  1.  An  anterior 
edge  (*,  fig.  48),  continuous  with  the  anterior  lip  of  the  obturator  foramen.  2.  A  poste- 
rior sharp  edge,  called  crest  of  the  pubes  (**,  figs.  47  and  48),  a  continuation  of  the  hori- 
zontal ridge,  which  we  have  described  as  forming  the  lower  boundary  of  the  internal 
iliac  fossa.  3.  A  base,  presenting  the  cmincntia  ileo-pectinea  {n  n),  which  corresponds  to 
the  femoral  artery,  and  upon  which  this  vessel  should  be  compressed,  care  being  taken 
to  direct  the  force  obliquely  downward  and  backward,  that  is,  perpendicularly  to  the  sur- 
face of  the  bone.  4.  The  summit  of  the  triangle  has  a  sharp  eminence,  which,  in  ema 
ciated  subjects,  forms  a  marked  projection  under  the  skin.  This  eminence,  called  spine 
of  the  pubes  (o),  gives  attachment  to  the  rectus  abdominis,  and  must  be  distinguished 
from  the  angle  of  the  pubes  (y'),  which  is  a  right  angle  formed  by  the  meeting  of  the  an- 
terior and  inferior  borders. 

The  posterior  border  (v  w,  fig.  48)  of  the  os  coxaj  commences  at  the  posterior  extremi- 
ty of  the  crest  of  the  ilium  by  a  sharp  eminence,  named  posterior  and  superior  spinous 
process  of  the  ilium  {v,  figs.  47,  48) ;  below  is  a  notch,  which  separates  it  from  another 
eminence,  the  posterior  inferior  spinous  process  of  the  ilium  {v').  Below  this  is  a  very 
large  notch,  the  sciatic  notch  of  the  coxa  (v  z,  fig.  47),  which  contributes  to  form  the  great 
sciatic  notch,  which  we  shall  notice  in  the  general  description  of  the  pelvis.  This  notch 
is  terminated  below  by  a  sharp  ridge,  called  the  sciatic  spine  (z) ;  as  this  spine  some- 
times projects  inward,  can  it,  as  some  have  imagined,  press  upon  the  foetal  head  when 
it  is  clearing  the  lower  outlet  of  the  pelvis  ]  Between  this  spine  and  the  tuberosity  of 
the  ischium  (r  w  )  is  a  small  but  well-marked  groove,  over  which  the  tendon  of  the  ob- 
turator internus  passes. 

Internal  Structure. — Like  all  broad  bones,  the  haunch  bone  is  composed  of  spongy  sub- 
stance contained  between  two  laminae  of  compact  tissue  ;  at  the  bottom  of  the  acetabu- 
lum, and  in  the  double  concavity  of  the  iliac  fossae,  it  is  thin  and  semi-transparent ;  it 
is  thick  at  the  circumference,  the  crest  of  the  ilium,  the  upper  and  back  part  of  the  ace» 

M 


dP  OSTEOLOGY. 

tabulum,  the  articular  portion  of  the  pubes,  and  more  particularly  at  the  tuberosity  of 
the  ischium. 

Cminr.xions. — The  OS  coxae  unites  with  its  fellow  of  the  opposite  side,  with  the  sa- 
crum, and  with  the  femiir. 

Development. — The  os  coxae  is  developed  from  three  primitive,  and  five  secondary 
points  of  ossification.  The  three  primitive  points  remain  distinct  until  a  very  advanced 
period,  and  therefore  botli  ancient  and  modern  anatomists  have  incorrectly  described 
them  as  separate  bones,  under  the  names  of  ilium,  ischium,  and  pubes.  The  ilium  (1, 
/iff.  48)  comprehends  the  upper  part  of  the  acetabulum,  and  the  broad,  curved,  and  trian- 
gular surface  above  it.  The  pubes  (2)  comprises,  1.  The  inner  part  of  the  acetabulimi. 
2.  The  horizontal,  prismatic,  and  triangular  column  that  bounds  the  obturator  foramen 
above,  and  which  is  called  the  body  of  the  pubes  (/).  3.  The  vertical  descending  branch, 
flattened  in  front  and  behind,  which  bounds  the  same  foramen  on  the  inside,  and  is  call- 
ed the  descending  ramus  of  the  pubes  (k,  jigs.  47,  48). 

The  ischium  (3,  fig.  48)  comprises,  1.  The  lower  part  of  the  acetabulum.  2.  A  verti- 
cal column,  very  thick,  prismatic,  and  triangular,  which  forms  the  tuberosity  below,  and 
bounds  the  obturator  foramen  on  the  outside  :  this  is  the  body  of  the  ischium  (/,  figs.  47 
and  48).  3.  An  ascending  branch,  sloping  inward,  flattened  in  front  and  behind,  which 
bounds  the  foramen  below  and  on  the  inside,  and  joins  the  descending  ramus  of  the 
pubes  ;  this  is  the  ascending  ramus  of  the  ischium  (e,  fig.  48).  The  limits  of  these  three 
pieces  are  marked  before  complete  development  by  three  cartilaginous  hnes,  united  like 
the  letter  Y,  at  the  bottom  of  the  cotyloid  cavity  (see  fig.  48),  which  is  the  place  where 
the  three  primitive  osseous  points  meet ;  and  this  fact  has  contributed,  in  no  small  de- 
gree, to  establish  that  law  of  osteogeny  which  we  noticed  in  our  general  remarks,  viz., 
that  when  an  articular  cavity  exists  upon  the  surface  of  a  bone  which  is  developed  from 
several  points,  these  points  always  unite  in  that  cavity. 

The  following  are  the  complementary  points  :  1.  One  at  the  bottom  of  the  acetabulum, 
pointed  out  by  M.  Serres,*  and  shaped  like  the  letter  Y ;  2.  The  marginal  epiphysis, 
which  occupies  and  forms  the  entire  length  of  the  crest  of  the  ilium  ;  3.  The  epiphysis 
of  the  tuberosity  of  the  ischium,  which  stretches  along  the  ascending  ramus ;  4  and  5. 
Two  epiphyses,  which  do  not  seem  constant ;  one  occupies  the  anterior  and  inferior  spi- 
nous process  of  the  ilium ;  the  other,  still  more  rare,  occupies  the  angle  of  the  pubes. 

The  ossification  of  the  os  coxae  commences  first  in  the  ilium,  in  the  ischium  next,  and 
in  the  pubes  last.  The  osseous  germ  of  the  ilium  appears  on  the  fiftieth  day,  that  of  the 
iscliium  at  the  end  of  the  third  month,  and  that  of  the  pubes  at  the  end  of  the  fifth  month. 
At  birth,  the  ossification  of  the  os  coxae  is  not  far  advanced  ;  the  acetabulum  is  in  a  great 
measure  cartilaginous.  The  ascending  ramus  of  the  ischium,  the  descending  ramus  of 
the  pubes,  and  the  entire  circumference  of  the  ilium,  are  also  cartilaginous.  These  three 
pieces  are  imited  together  from  the  thirteenth  to  the  fifteenth  year.  At  the  same  time, 
the  secondary  points  of  ossification  appear,  and  successively  unite  with  the  primitive. 
This  union  is  completed  from  the  tenth  to  the  twentieth  year ;  the  epiphysis  of  the  crest 
of  the  ilium  alone  remains  separate  until  the  age  of  twenty-two,  twenty-four,  or  even 
twenty-five  years. 

The  Pelvis  in  general. 

The  sacrum,  the  coccyx,  and  the  haunch  bones  having  now  been  described,  we  are 
enabled  to  study  the  bony  cavity  which  they  concur  in  forming.  It  is  called  the  pelvis 
(fig.  48),  and  forms  for  the  lower  extremities  an  osseous  girdle,  analogous  to  that  which 
the  shoulders  form  for  the  upper  extremities.  The  pelvis  or  basin,  so  named  because  it 
has  been  compared  to  a  vase,  is  a  large,  irregular,  bony  cavity,  open  above  and  below, 
which  supports  the  vertebral  column  behind,  and  is  itself  supported  by  the  thigh  bones 
on  the  sides  and  in  front.  In  an  adult  of  ordinary  stature,  tlie  pelvis  divides  the  body 
into  two  equal  parts.  In  the  foetus  the  part  of  the  body  above  the  pelvis  is  much  longer 
than  that  below ;  in  adults  of  large  stature,  on  the  other  hand,  the  part  below  is  consid- 
erably longer  than  that  above. 

The  pelvis  is  symmetrical,  but  of  a  very  irregular  figure  ;  we  may  say,  upon  the  whole, 
that  it  forms  a  truncated  cone,  presenting,  1.  An  upper  part  or  great  pelvis,  oval  trans- 
versely, much  expanded  on  each  side,  and  notched  in  front ;  2.  A  sort  of  contracted  canal, 
below  this  upper  part,  which  is  called  the  little  pelvis.  When  the  pelvis  is  examined  in 
the  skeleton,  it  has  not  the  horizontal  position  which  it  presents  when  resting  on  the 
tuberosities  of  the  ischium  and  the  extremity  of  the  coccyx.  It  is  inclined  with  regard 
to  the  axis  of  the  body.  The  obliquity  of  the  pelvis  is  not  the  same  throughout,  and  we 
have  therefore  to  consider  two  axes,  one  for  the  great  and  one  for  the  little  pelvis.  The 
axis  of  the  great  pelvis  is  directed  obliquely  downward  and  backward,  and  is  represented 
by  a  line  passing  from  the  umbilicus  towards  the  lower  part  of  the  curvature  of  the  sa- 
crum ;  the  axis  of  the  little  pelvis,  on  the  contrary,  is  directed  downward  and  forward, 

*  This  point  of  ossification  has  been  regarded  as  the  vestige  of  a  bone  peculiar  to  marsupial  animals,  and 
named  marsupial  bone ;  but  this  view  is  incorrect,  for,  according  to  Cuvier,  this  fourth  piece  is  found  in  mar- 
supials themselves  at  the  bottom  of  the  cotyloid  cavity,  whereas  the  marsupial  bone  is  a  superadded  portion 
of  the  skeleton,  which  supports  the  pouch  in  these  animals. 


THE   PELVIS    IN    GENERAL.  9t 

and  is  represented  by  a  line  passing  from  the  upper  part  of  the  curvatuie  of  the  sacrum 
through  the  centre  of  the  lower  opening  or  outlet  of  the  pelvis.  From  the  direction  of 
these  two  axes,  it  follows  that  the  line  of  direction  of  the  pelvis  is  a  curve  with  the  con- 
cavity forward,  and  which  is  pretty  correctly  represented  by  the  curvature  of  the  ante- 
rior surface  of  the  sacrum.  This  sort  of  incurvation  of  the  pelvis  is  an  anatomical  fact 
of  the  greatest  consequence,  not  only  on  account  of  the  important  office  which  this  part 
of  the  skeleton  performs  in  the  mechanism  of  standing,  but  also  because,  without  an  ac- 
quaintance with  it,  it  is  impossible  to  understand  the  mechanism  of  natural  labour,  the 
curved  canal  of  the  pelvis  being  the  path  which  the  infant  has  to  traverse  in  passing  out 
of  the  cavity. 

The  obliquity  of  the  pelvis  varies  at  different  ages  and  in  different  individuals :  it  is 
pretty  exactly  measured  by  the  prominence  of  the  sacro-vertebral  angle. 

In  the  infant  the  pelvis  deviates  greatly  from  the  horizontal  direction  ;  its  upper  aper- 
ture looks  almost  directly  forward  :  in  the  adult  it  looks  much  more  upward  ;  and  in  the 
aged  it  again  looks  forward,  as  in  the  infant,  but  from  a  very  different  cause.  In  the 
foetus  the  superior  aperture  is  turned  forward,  even  when  the  body  is  upright :  at  this 
age  the  obliquity  of  the  pelvis  is  inherent  in  its  form ;  but  in  the  aged  the  pelvis  looks 
forward,  because  the  trunk  is  curved  in  the  same  direction,  and  tends  towards  a  hori- 
zontal position  as  in  quadrupeds.  Thus  in  the  foetus  the  pelvis  has  an  obliquity  which 
depends  on  form  ;  in  the  aged  the  obliquity  depends  upon  attitude. 

The  human  pelvis  is  much  larger  than  that  of  any  other  animal ;  and  this  larger  size 
is  connected  with  the  important  office  it  performs  in  maintaining  the  erect  posture  of 
the  trunk. 

There  is  no  part  of  the  skeleton  the  form  and  dimensions  of  which  so  readily  discrim- 
inate the  sex  of  the  individual ;  in  the  male  the  height  predominates  ;  in  the  female  the 
breadth.  By  comparing  the  distance  between  the  crests  and  the  anterior  and  the  pos- 
terior spinous  processes  of  the  ilia,  and  between  the  obturator  foramina,  in  the  two  sex- 
es, we  find  that  the  transverse  dimensions  are  much  greater  in  the  female  ;  the  same  is 
observed  in  the  antero-posterior  dimensions,  which  may  be  easily  proved  by  measuring 
the  distance  between  the  symphysis  pubis  and  the  sacro-vertebral  angle,  and  the  dis- 
tance between  each  obturator  foramen  and  the  sacro-iliac  symphysis  on  the  opposite 
side.  We  shoidd  add  that,  in  the  female,  1.  The  iliac  fossae  are  larger,  and  turned  more 
outward  than  in  the  male  ;  hence  the  prominence  of  the  hips.  2.  The  crest  of  the  ilium 
is  not  so  much  twisted  in  form  of  the  italic  S.  3.  The  interval  between  the  symphysis 
pubis  and  the  acetabulum  is  greater ;  this  is  partly  the  cause  of  the  great  prominence  of 
the  trochanters,  and  the  separation  of  the  femora,  which  gives  the  female  a  peculiar  gait 
in  walking.  4.  The  superior  strait  or  brim  is  wider  in  every  direction.  5.  The  tuber- 
osities of  the  ischia  are  more  separated,  and  the  symphysis  pubis  is  not  so  deep.  6.  The 
obturator  foramen  is  triangular.  7.  The  arch  of  the  pubis  is  rounded,  wider,  and  more 
curved,  while  in  the  male  it  is  triangular  and  narrower.  8.  The  inner  edges  of  the  ascend- 
ing rami  of  the  ischia  are  prominent,  and  look  less  directly  downward  than  in  the  male. 
Such  are  the  differences  of  the  pelvis  as  regards  sex ;  we  see  that,  for  the  most  part, 
they  may  be  comprehended  in  the  following  proposition : 

The  female  pelvis  exceeds  the  male  in  its  horizontal  diameters ;  the  male  pelvis  exceeds  the 
femxde  in  its  vertical  diameters. 

Regions  of  the  Pelvis. 

Under  this  title  we  shall  examine  in  succession  the  external  and  internal  surface  of 
the  pelvis,  the  upper  circumference  or  base,  and  the  lower  circumference  or  summit. 

The  external  surface  of  the  pelvis  must  be  examined  in  front,  behind,  and  on  the  sides. 

Anterior  Region. — 1.  In  the  median  line  we  observe  the  symphysis  pubis  (y  y,Jig.  48), 
varying  from  fifteen  to  eighteen  or  twenty  pig.  49. 

lines  in  length,  always  longer  in  the  male, 
and  resembling  a  vertical  column.  It  is  ob- 
liquely directed  downward  and  backward, 
which  direction  is  peculiar  to  man;  in  all 
other  animals,  as  Cuvier  has  remarked,  it  is 
placed  horizontally.  2.  On  each  side  we  find 
the  descending  ramus  of  the  pubes  (k),  which 
is  irregularly  quadrilateral,  and  gives  attach- 
ment to  several  muscles.  3.  Outside  the  pu- 
bic column  there  is,  on  each  side,  the  obtu- 
rator foramen  (A). 

Posterior  Region. — On  this  we  observe,  1, 
the  ridge  of  the  sacnim  in  the  median  line  ; 
2,  and  on  each  side  the  sacral  grooves  into 
which  the  posterior  sacral  foramina  open  ;  they  are  much  deepened  above,  because  the 
back  part  of  the  ilium  projects  behind  the  sacrum :  we  find  here,  also,  two  ranges  of 
eminences,  corresponding  to  the  articular  and  transverse  processes,  and  likewise  the 
back  of  the  sacro-iliac  articulation. 


«g  OSTEOLOGY. 

Each  lateral  region  is  formed  by  the  external  iliac  fossa,  the  acetabulum,  and  a  con- 
siderable portion  of  the  body  of  the  ischium  below  this  cavity. 

The  internal  surface  of  the  pelvis  is  divided  into  two  parts  :  an  upper,  which  is  much 
expanded,  and  constitutes  the  great  or  false  pelvis ;  and  a  lower,  more  contracted,  named 
the  small  or  true  pelvis.  These  two  portions  of  the  same  cavity  are  separated  by  a  cir- 
cular prominence,  formed  in  a  great  measure  by  the  horizontal  ridge  (m  n  o),  which  we 
have  described  as  constituting  the  lower  boundary  of  the  internal  iliac  fossae.  The 
whole  space  circumscribed  by  this  line  has  been  named  the  brim,  superior  orifice,  or  supe- 
rior strait  of  the  pelvis. 

The  great  pelvis  presents,  1.  In  front,  an  extensive  notch  (m  y'  u) ;  2.  Behind,  the  sacro- 
vertehral  angle  ox  promontory  of  the  sacrum  (below  d) ;  3.  And  on  the  sides,  the  internal  iliac 
fossae  (1  and  t),  which  form  an  inclined  plane  on  each  side,  fitted  to  direct  the  weight 
of  the  viscera  which  rest  upon  them,  inward  and  forward. 

The  small  pelvis  is  a  cavity,  the  apertures  of  which  are  contracted,  and  therefore  na- 
med straits,  and  the  middle  portion  is  expanded,  and  called  excavation. 

We  shall,  therefore,  examine  separately  its  superior  opening  or  upper  strait,  its  infe- 
rior opening  or  lower  strait,  and  its  middle  portion  or  excavation. 

The  superior  strait  or  brim  is  irregularly  circular,  and  has  been  compared  to  an  oval, 
an  ellipse,  or  a  curvilinear  triangle  ;  but  none  of  these  descriptions  can  give  any  correct 
idea  of  its  shape.  The  circumference,  commencing  behind,  at  the  articulation  between 
the  sacrum  and  the  fifth  lumbar  vertebra,  is  formed  by  the  projection  of  the  anterior 
edge  {g  d)  of  the  base  of  the  sacrum,  by  the  horizontal  ridge  (m  n),'on  the  inner  surface 
of  the  iliac  bones,  by  the  pectineal  line  (w  o),  and  terminates  in  the  spine  of  the  pubes  (o). 
The  superior  strait  has  four  diameters,  an  antero-posterior,  a  transverse,  and  two  oblique. 
The  antero-posterior  or  sacro-pubic  diameter  (d  y)  is  generally  four  inches  in  length  ;  the 
transverse  (m  m),  which  is  the  longest,  is  five  inches  ;  and  the  two  oblique  {n  g),  which 
are  measured  from  the  eminentia  ilio-pectinea  on  one  side,  to  the  sacro-iliac  symphysis 
on  the  other,  are  four  inches  and  a  half  These  measures  are  taken  from  a  well-form- 
ed female  pelvis,  and  it  is  chiefly  in  the  female  that  they  are  important,  on  account  of 
their  reference  to  the  process  of  parturition.  In  the  male,  all  the  diameters  of  the  upper 
strait  are  smaller. 

The  inferior  or  perineal  strait,  inferior  orifice  or  outlet  of  the  small  pelvis,  presents  three 
deep  notches  separated  by  three  eminences,  so  that  when  the  pelvis  is  placed  upon  a 
horizontal  plane,  it  appears  to  rest,  as  it  were,  upon  three  feet.  Of  these  notches,  one  is 
anterior,  viz.,  the  arch  of  the  pubes  {x  y  x);  the  others  are  lateral,  and  somewhat  poste- 
rior ;  they  are  the  ischiatic  notches  («'  z,  fig.  47).  The  arch  of  the  pubes  is  angular  in  the 
male,  but  rounded  in  the  female,  forming  a  true  arch,  which  receives  the  occipital  bone 
of  the  foetus  in  the  great  majority  of  labours  ;  it  is  formed  on  each  side  by  the  ascend- 
ing ramus  of  the  ischium,  the  edge  of  which  is  somewhat  everted,  so  that  the  head  of 
the  foetus  when  passing  under  the  arch  glides  over  a  sort  of  inclined  plane,  instead  of 
being  in  contact  with  the  edge  of  the  bone.  The  transverse  diameter  of  the  pubic  arch 
near  the  upper  part  has  been  calculated  at  one  inch  ;  that  of  the  lower  part  {x  x,  fig.  48), 
at  three  inches.  The  two  lateral  notches  are  formed  behind  by  the  sacrum  and  the 
cocc)rx ;  in  front,  by  the  sciatic  notch  of  the  os  innominatum  ;  they  are  therefore  called 
also  the  sacro-sciatic  notches.  They  are  very  deep,  and  reach  almost  to  the  superior 
strait  of  the  small  pelvis.  Of  the  three  emineiwes  which  separate  the  notches,  the  poste- 
rior is  formed  by  the  coccyx,  and  the  two  anterior  by  the  tuberosities  of  the  ischia,  which 
are  situated  on  a  lower  plane  than  the  first ;  from  this  peculiar  arrangement,  the  whole 
weight  of  the  body,  in  the  sitting  posture,  rests  upon  the  tuberosities  of  the  ischia,  and 
not  at  all  upon  the  point  of  the  coccyx.  The  diameters  of  the  lower  aperture  of  the 
pelvis  are,  in  reference  to  parturition,  of  equal  importance  with  those  of  the  upper,  and 
have  been  accurately  determined.  The  antero-posterior  diameter,  or  cocci-pubic,  so  called 
because  it  extends  from  the  symphysis  pubis  to  the  point  of  the  coccyx,  is  four  inches, 
but  may  be  increased  to  four  inches  and  a  half  by  depression  of  the  coccyx.  The  trans- 
verse or  bisciatic  diameter,  which  stretches  between  the  tuberosities  of  the  ischia,  is  four 
inches,  which  is  invariable  ;  and,  lastly,  the  two  oblique  diameters,  which  extend  from  the 
middle  of  the  sacro-sciatic  ligament  on  one  side  to  the  tuberosity  of  the  ischium  on  the 
other,  are  also  four  inches  each.  These  dimensions,  which  are  taken  from  a  well-formed 
female  pelvis,  are  greater  than  in  the  male. 

Excavation. — The  excavation  or  cavity  of  the  true  pelvis  is  formed,  1 .  Behind,  by  the 
sacrum  and  coccyx,  the  concavity  of  which  varies  in  different  individuals,  but  is  gener- 
ally shallower  in  the  female  than  in  the  male.  The  height  of  these  two  bones  is  four 
inches  and  a  half;  the  greatest  depth  of  their  concavity  from  ten  to  twelve  lines.  2.  In 
front,  by  the  symphysis  and  back  part  of  the  pubes,  forming  a  plane  inclined  downward 
and  backward  ;  outside  the  pubes  is  the  inner  opening  of  the  obturator  foramen.  3.  On 
the  sides,  the  excavation  is  formed  by  two  smooth  planes  inclined  downward  and  in- 
ward ;  they  are  about  three  inches  and  a  half  in  height,  and  are  bounded  behind  by  the 
sciatic  notch. 

It  is  of  great  consequence  to  notice  these  two  inclined  planes,  because  they  perform 


THE    FEMUR.  ffj 

an  importcint  part  in  the  mechanism  of  parturition.  The  diameters  of  the  excavation 
being  of  little  value  in  an  anatomical  point  of  view,  the  student  is  referred  to  works  on 
midwifery  for  an  account  of  them. 

The  superior  circumference  or  base  of  the  pelvis  looks  forward,  and  is  formed  behind  by 
the  sacro- vertebral  angle  ;  on  each  side  by  the  upper  border  of  the  ilium,  and  in  front  by 
the  anterior  border  of  the  same  bone.  It  presents,  1 .  In  front,  a  vast  notch  {u  u,  fig.  48), 
in  which  we  observe  in  the  median  line  the  upper  part  of  the  symphysis  pubis  («')  ;  on 
each  side,  proceeding  from  within  outward,  the  spine  of  the  pubes  (o),  the  pectineal  sur- 
face (o  n),  the  ilio-pectineal  eminence  («  w),  and  the  angular  groove  for  the  psoas  and 
iliacus  muscles  (n  u").  In  all  this  extent  the  notch  is  horizontal,  but  beyond  the  groove 
it  slants  obliquely  upward  and  outward,  to  the  anterior  superior  spinous  process  of  the 
ilium  (u),  where  it  terminates.  2.  Behind,  the  great  circumference  of  the  pelvis  presents 
the  sacro-vertebral  angle,  and  on  each  side  a  small  notch  between  the  vertebral  column 
and  the  back  of  the  crest  of  the  ilium.  3.  Laterally,  we  observe  the  crest  of  the  ilium 
(m  v),  bent  much  more  outward  in  the  female  than  in  the  male. 

The  dimensions  of  the  upper  circmnference  of  the  pelvis,  measured  in  a  well-formea 
female,  are  the  following :  1.  Between  the  anterior  superior  spines  of  the  ilia,  from  eight 
to  nine  inches.  2.  From  the  middle  of  the  crest  of  one  ilium  to  that  of  the  other,  from 
nine  to  ten  inches. 

The  inferior  circumference  of  the  pelvis  forms  the  lower  strait,  which  has  been  already 
described. 

General  Development  of  the  Pelvis. 

The  pelvis  in  the  first  periods  of  life  participates  in  the  slow  development  of  the  lower 
extremities.  Its  dimensions,  especially  in  the  foetus  and  in  infancy,  are  so  small,  that 
it  is  unable  to  receive  into  its  cavity  many  of  the  organs  which  are  afterward  contained 
in  it ;  this  is  one  of  the  principal  causes  of  the  prominence  of  the  abdomen  of  the  foetus. 
The  smaller  capacity  of  the  pelvis  results  also  from  the  absence  of  the  iliac  fossae,  for 
these  bones  are  neither  twisted  nor  excavated,  but  straight  and  flat.  Nevertheless,  the 
upper  or  iliac  portion  of  the  pelvis  is  proportionally  more  developed  than  the  lower  or 
cotyloid,  doubtless  because  this  latter  part  belongs  especially  to  the  lower  extremities, 
and  also  serves  as  a  protection  to  the  genital  organs,  both  of  which  are  in  a  rudimentary 
state  in  the  foetus.  If  we  examine  in  detail  the  differences  in  size,  considered  only 
with  reference  to  the  various  diameters,  we  shall  find  that  the  transverse  are  very  small, 
because  in  front  the  cotyloid  cavities  are  scarcely  developed,  and  all  the  pubic  region  is 
contracted ;  and  behind,  the  iliac  bones  are  more  closely  approximated  to  each  other,  on 
account  of  the  small  size  of  the  sacrum.  The  antero-posterior  diameters  appear  longer, 
on  account  of  the  shortness  of  the  transverse.  But  the  most  characteristic  feature  of 
the  pelvis  in  the  early  periods  of  life  is  its  much  greater  inclination  than  in  the  adult. 
In  the  latter,  indeed,  a  horizontal  line  drawn  from  the  upper  part  of  the  symphysis  pubis 
would  fall  only  a  few  lines  below  the  base  of  the  sacrum,  while  in  the  foetus  a  similar 
horizontal  hue  would  fall  nearer  the  lower  than  the  upper  part  of  the  sacrum.  This,  as 
well  as  the  small  capacity  of  the  pelvis,  is  the  cause  of  the  forward  position  of  the  blad- 
der, bringing  the  whole  of  its  anterior  surface  to  correspond  with  the  parietes  of  the  ab- 
domen, and,  consequently,  rendering  it  more  easily  accessible  to  instruments  introduced 
above  the  pubes. 

We  have  already  remarked,  that  the  obliquity  of  the  pelvis  in  the  aged  is  not  of  the 
same  kind  as  that  in  the  foetus ;  and  we  should  add  here,  that  there  is  no  change  in  the 
relative  position  of  the  bladder,  which,  as  in  the  adult,  corresponds  to  the  back  of  the  os 
pubis. 

The  Thigh. 

The  Femur  {fgs.  49  and  50). 

The  femur,  or  thigh  bone,  situated  between  the  pelvis  and  the  leg,  is  the  longest  and 
largest  bone  of  the  skeleton.  It  is  proportionally  larger  in  man  than  in  any  other  ani- 
mal ;  this  is  connected  with  the  ofiice  which  it  performs,  of  supporting,  by  itself  alone, 
the  weight  of  the  body  in  standing,  and  transmitting  it  to  the  leg.  It  is  obliquely  di- 
rected downward  and  inward.  This  obliquity  is  greater  in  the  female  than  in  the  male, 
on  account  of  the  greater  distance  between  the  acetabula.  Too  great  an  obliquity  is  in- 
jurious both  in  standing  and  walking,  and  constitutes  a  well-known  deformity. 

The  femur  describes  a  curve  in  front  and  behind,  the  convexity  of  which  looks  for- 
ward, and  leaves  a  sort  of  excavation  behind,  which  is  occupied  by  the  numerous  pow- 
erful muscles  which  bend  the  leg  upon  the  thigh.  This  curvature,  of  which  the  siun- 
mit  is  in  the  middle  of  the  bone,  explains  why  fractures  generally  occur  here.  It  is 
generally  very  great  in  subjects  affected  with  rickets.  Independently  of  tliis  antero- 
posterior curvature,  the  femur  is  slightly  twisted  upon  itself  This  curvature  of  torsion 
seems  to  me  to  be  connected  with  the  course  of  the  femoral  artery,  which  passes  round 
the  shaft  of  the  bone  from  one  surface  to  the  other.  Lastly,  at  its  upper  part  it  presents 
an  angular  curve,  which  we  shall  notice  presently. 


94 


OSTEOLOGY. 


Like  all  other  long  bones,  the  femur  is  divided  into  a  body  and  extremities. 

Of  the  Body. — ^The  body  or  shaft  is  prismatic  and  triangular,  with  three  surfaces  and 
three  edges. 

The  anterior  surface  (a,  fig.  50)  is  rounded,  and  has  a  cylindrical  aspect ;  it  is  broader 
below  than  above. 

The  internal  surface  {h,  fig.  49)  is  flat,  it  becomes  much  wider  below,  and  then  looks 
backward.  The  femoral  artery  corresponds  to  this  surface,  and  may  be  compressed 
upon  it  towards  the  middle  third  of  the  thigh. 

The  external  surface  (c)  is  much  narrower  than  the  internal,  and  is  slightly  excavated 
throughout  its  extent. 

Of  the  three  edges,  the  internal  and  the  external  are  rounded,  and  scarcely  distinguish- 


Fig.  49. 


Fig.  50. 


able  from  the  surfaces  which  they  separate. 
The  posterior  edge  {e  df),  on  the  contrary, 
is  very  rough  and  prominent,  and  has,  there- 
fore, been  called  the  linca  aspera :  it  is  di- 
vided into  tico  lips  and  an  interspace,  for  the 
sake  of  facilitating  the  description  of  the 
numerous  muscles  to  which  it  gives  attach- 
ment. It  is  more  rough  above  than  below, 
and  is  bifurcated  at  both  ends.  Of  the  two 
branches  of  the  upper  bifurcation,  the  exter- 
nal (e),  extremely  rough,  is  occasionally  sur- 
mounted by  a  considerable  eminence,  and 
prolonged  to  the  large  process  called  great 
trochanter.  The  internal  branch  is  less  pro- 
jecting, and  terminates  on  the  inside  in  a 
smaller  eminence  called  lesser  trochanter. 
The  outer  branch  (/)  of  the  lower  bifurca- 
tion runs  towards  the  outside  of  the  lower 
extremity  of  the  femur,  and  terminates  in 
an  eminence,  below  which  is  a  small  de- 
pression, to  which  the  external  head  of 
the  gastrocnemius  is  attached.  The  in- 
ner branch  (g)  is  nearly  effaced  at  the  part 
where  the  femoral  artery  passes  over  it : 
below  this  it  appears  again,  and,  like  the 
outer  branch,  terminates  in  a  well-marked 
prominence,  to  which  the  adductor  magnus 
is  attached,  and,  below  it,  the  inner  head 
of  the  gastrocnemius.  The  triangular  in- 
terval, included  between  the  two  branches 
of  the  bifurcation,  corresponds  to  the  popli- 
teal artery  and  vein.  The  nutritious  fora- 
men (Ji)  is  situated  in  the  linea  aspera ;  it  passes  from  below  upward. 

The  superior  extremity  of  the  femur  forms  an  obtuse  angle  with  the  body,  and  presents 
a  head,  a  neck,  and  two  unequal  eminences,  named  trochanters,  the  greater  and  lesser. 

The  head  (i,  figs.  49  and  50)  is  the  most  regularly  spheroidal  of  all  the  eminences  in 
the  skeleton,  and  forms  nearly  two  thirds  of  a  sphere.  In  the  middle  of  it  we  observe  a 
rough  depression  (k)  of  variable  dimensions,  which  gives  attachment  to  the  round  Uga- 
ment.  The  neck  (/),  so  called  because  it  supports  the  head  of  the  bone,  is  obliquely  di- 
rected upward  and  inward ;  it  forms  an  obtuse  angle  with  the  body  of  the  femur  {angle 
of  the  femur),  retiring  on  the  inside  and  projecting  on  the  outside,  the  degree  of  which 
varies  in  different  individuals,  at  different  ages,  and  in  the  two  sexes.  In  fact,  it  is 
sometimes  a  very  obtuse  and  sometimes  a  right  angle  :  this  last  is  most  common  in  the 
female,  and  is  one  of  the  causes  of  the  prominence  in  her  of  the  great  trochanter.  The 
neck,  which  varies  in  length  in  different  subjects,  is  flattened  in  fi-ont  and  behind,  so 
that  its  verticed  diameter  is  double  the  antero-posterior ;  hence  it  has  more  power  in 
resisting  force  applied  from  above  downward  than  from  before  backward,  which  is  a 
great  advantage,  since  the  causes  which  would  produce  fractures  are  almost  always  ap- 
plied in  the  former  direction.  The  anterior  surface  of  the  neck  is  much  shorter  than 
the  posterior,  which  is  also  slightly  concave.  The  upper  edge  is  very  short,  and  pre- 
sents a  great  many  nutritious  foramina ;  the  lower  edge  is  about  double  the  length  of 
the  upper.  The  base  of  the  neck  is  marked  by  a  number  of  nutritious  foramina ;  it  is 
bounded  in  front  by  some  inequaUties ;  behind  by  the  great  trochanter  above,  and  the 
lesser  trochanter  below ;  and  in  the  interval  between  these  two,  by  a  projecting  ridge, 
which  unites  them,  and  which  is  called  the  inter-trochanteric  line.  Behind,  at  the  root 
of  the  great  trochanter,  there  is  a  deep  pit,  which  weakens  the  neck  of  the  bone  in  this 
situation,  fiom  which  circumstance  fractures  most  generally  occur  at  that  point. 
The  great  trochanter  (m)  is  situated  a  little  behind,  at  the  outer  and  upper  part  of  the 


THE  FEMUR, THE  PATELLA.  TO 

lemur.  It  is  on  a  lower  level  than  the  head,  and  nearly  in  the  same  axis  as  the  shaft, 
which  it  prolongs  upward.  It  is  of  considerable  size,  and  forms  a  very  marked  promi- 
nence under  the  skin.  It  should  be  carefully  studied  in  its  relations,  1.  With  the  crest 
of  the  ilium,  beyond  which  it  projects  on  the  outside  ;  2.  With  the  external  condyle  of 
the  femur ;  3.  With  the  external  malleolus,  because  these  relations  constantly  serve  as 
a  guide,  both  in  the  diagnosis,  and  the  reduction  of  dislocations  of  the  femur,  and  of  frac- 
tures of  the  neck  or  shaft  of  that  bone.  The  great  trochanter,  which  is  intended  solely 
for  muscular  insertions,  is  of  a  quadrilateral  figure,  flattened  from  without  inward,  and 
presents,  1.  An  external  surface,  which  is  convex,  and  terminates  below  in  a  projecting 
ridge  for  the  vastus  externus,  and  is  traversed  by  an  oblique  line  running  downward  and 
backward,  to  which  the  gluteus  medius  is  attached  ;  2.  An  internal  surface,  on  which  we 
find  a  depression  called  digital,  or  trochanteric  cavity,  where  the  tendon  of  the  obturator 
externus  is  inserted ;  3.  A  superior  border,  to  which  the  gluteus  minimus,  the  pyramidalis, 
and  obturator  internus  are  inserted  ;  4.  An  anterior  border,  which  is  often  surmounted  by 
a  large  tubercle,  gives  attachment  to  the  vastus  externus ;  and,  5.  A  posterior  border,  which 
gives  attachment  to  the  quadratus  femoris. 

The  lesser  trochanter  (n)  is  situated  on  the  inside,  behind,  and  below  the  base  of  the 
neck  of  the  femur  ;  it  is  a  sort  of  conoid  tubercle,  and  gives  attachment  to  the  common 
tendon  of  the  psoas  and  iliacus  muscles. 

The  lower  end  of  the  shaft  of  the  femur  is  of  considerable  size  ;  it  is  broad,  transverse- 
ly flattened  in  front  and  behind,  and  divided  into  two  convex  articular  processes,  called 
internal  (r)  and  external  (*)  condyles  of  the  femur.  The  external  condyle  is  in  the  same 
line  as  the  shaft  of  the  femur.  The  internal  condyle  projects  on  the  inside  of  the  axis 
of  the  bone,  and  below  the  external  condyle,  so  that  when  both  condyles  rest  on  the 
same  horizontal  plane,  the  femur  is  directed  obliquely  downward  and  inward.  The  two 
condyles  are  separated  behind  by  a  deep  notch,  called  inter-condyloid  notch  (o,  fig.  49) ;  in 
front  their  union  forms  a  sort  of  pulley,  the  femoral  trochlea  {t,  fig.  50),  on  which  the  pa- 
tella rests.  That  portion  of  the  trochlea  which  belongs  to  the  external  condyle  is  larger, 
more  prominent,  and  higher  than  that  which  belongs  to  the  internal.  Each  condyle  has 
three  surfaces  :  1.  The  lower  surface,  articular,  convex,  and  rounder  behind  than  in  front, 
is  in  contact  with  the  tibia  and  the  patella ;  the  lower  surface  of  the  internal  condyle  is 
more  prominent  behind  than  that  of  the  external.  2.  The  internal  surface  of  the  external 
condyle,  and  the  external  surface  of  the  internal  condyle,  are  deeply  excavated,  and  give 
insertion  to  the  crucial  ligaments.  3.  The  internal  surface  of  the  internal  condyle  and  the 
external  surface  of  the  external  condyle  present  two  enlargements,  called  tuberosities  of 
the  femur. 

The  internal  tuberosity  (v)  is  the  larger,  and  has  behind  a  depression  situated  above  the 
tubercle  for  the  adductor  magnus,  already  described.  The  external  tuberosity  {w)  is  less 
prominent,  and  presents  two  depressions  separated  by  a  tubercle,  which  may  be  easily 
felt  under  the  skin  in  emaciated  subjects.  The  inferior  groove  is  distinctly  marked,  and 
gives  origin  to  the  tendon  of  the  popliteus  muscle. 

Connexions. — The  femur  articulates  with  the  innominatum,  which  transmits  to  it  the 
weight  of  the  body,  and  with  the  tibia  upon  which  it  rests,  and  is  in  contact  with  the 
patella. 

Internal  Structure. — Like  all  long  bones,  the  femur  is  compact  in  its  shaft  and  spongy 
at  the  extremities  ;  its  medullary  canal  is  the  type  of  canals  of  that  kind. 

Development. — The  femur  is  developed  from  five  points :  of  these,  three  are  primitive, 
viz.,  one  for  the  shaft,  and  one  for  each  extremity ;  two  are  epiphysary,  one  being  for  each 
trochanter.  A  bony  point  first  appears  in  the  shaft,  from  the  thirtieth  to  the  fortieth  day ; 
the  osseous  germ  of  the  lower  extremity  is  visible  in  the  centre  of  the  cartilage,  during 
the  last  fifteen  days  of  foetal  life.  The  constancy  of  the  appearance  of  this  point  is  of 
great  importance  in  forensic  medicine,  because  its  existence  proves  at  once  that  the 
foetus  has  reached  the  full  term.  The  third  point  is  seen  in  the  head  of  the  femur,  at  the 
end  of  the  first  year  after  birth.  The  neck  has  no  separate  osseous  centre ;  it  is  formed 
by  an  extension  of  the  shaft.  The  nodule  of  the  great  trochanter  is  developed  from  three 
to  four  years  after  birth ;  that  of  the  lesser  trochanter,  from  the  thirteenth  to  the  four- 
teenth year. 

The  order  of  union  of  these  parts  does  not  coincide  with  that  of  their  appearance ;  it 
commences  after  puberty,  and  does  not  terminate  until  after  the  growth  of  the  body  is 
completed.  The  lesser  trochanter,  the  great  trochanter,  and  the  head,  are  successively 
attached  to  the  bone  about  the  eighteenth  year.  The  lower  extremity,  which  appeared 
first,  does  not  join  the  shaft  until  the  twentieth  year.  In  old  age  the  spongy  tissue  is 
frequently  so  delicate,  that  the  interior  of  the  neck  becomes  filled  with  an  adipose  tissae 
Uke  the  body  of  the  long  bones.  This  explains  the  frequency  of  fractures  in  this  situa- 
tion in  advanced  age. 

The  Patella  {jig.  51). 
The  patella  or  rotula,  so  named  from  its  rounded  shape,  resembhng  a  wheel,  is,  both 
from  its  size,  and  the  functions  which  it  performs,  the  most  important  of  those  bones 


96  OSTEOLOGY. 

which  have  been  called  sesamoid  (from  aijadfiT]),  on  account  of  their  resemblance  to  the 
sesamum  seed,  and  which  are  found  in  the  neighbourhood  of  various  articulations  that 
are  subjected  to  much  pressure.  It  is  situated  in  front  of  the  knee,  and  is  movable 
when  the  leg  is  extended ;  but  fixed  and  very  prominent  when  the  leg  is  flexed  upon  the 
thigh.  Its  mobility  allows  it  to  escape  the  injurious  effect  of  external  blows,  to  which 
it  would  be  subject  were  it  united  to  the  tibia  like  the  olecranon  process  to  the  ulna. 
It  is  the  most  variable  of  all  the  bones,  both  in  its  absolute  size,  and  in  the  proportion  of 
its  different  dimensions.  It  is  flattened  in  front  and  behind,  and  presents  an  interior  and 
a  posterior  surface,  and  a  circumference. 

The  anterior  or  subcutaneous  surface  {i,fig.  51)  is  convex,  and  covered  by  a  very  thick 
layer  of  fibrous  tissue,  intimately  adherent  to  the  bone. 

The  -posterior  ox  femoral  surface  (2,  fig.' 51)  corresponds  exactly  to  the  pulley  on  the 
lower  extremity  of  the  femur.  We  observe  on  it,  1.  An  articular  ridge  (x)  sloping  down- 
ward and  inward,  and  corresponding  to  the  groove  of  the  trochlea,  which  presents  the 
same  obliquity.  2.  On  each  side  of  this  ridge,  a  concave  articular  surface,  which  is  mould- 
ed upon  the  corresponding  condyle  of  the  femur ;  and  as  the  external  condyle  of  the 
femur  is  the  larger,  the  external  articular  surface  (y)  of  the  patella  is  much  greater  than 
the  internal.  From  this  inequality,  it  is  easy  at  once  to  distinguish  the  right  from  the 
left  patella. 

The  circumference  of  the  patella  resembles  a  curvilinear  triangle  ;  its  thick  base,  di- 
rected upward,  gives  attachment  to  the  tendon  of  the  rectus  femoris  and  to  the  tendons 
of  the  extensor  muscles  of  the  leg ;  and  its  apex  (z),  turned  downward,  and  somewhat 
pointed,  gives  attachment  to  the  ligamentum  patellae.  Its  sides  are  thin,  and  give  at- 
tachment to  some  aponeurotic  fibres  ;  so  that,  excepting  its  posterior  surface,  wliich  is 
articular,  the  whole  patella  is  enveloped  in  fibrous  tissue  ;  a  circumstance  which  is  in  ac- 
cordance with  its  peculiar  mode  of  development,  and  has  an  important  influence  over  its 
reunion  when  fractured. 

Internal  Structure. — Tlie  patella  is  entirely  composed  of  spongy  tissue,  covered  in 
front  by  a  thin  layer  of  compact  substance,  which  renders  it  very  liable  to  fracture,  and 
which  forms  a  very  remarkable  exception  to  the  generality  of  short  bones,  in  presenting 
well-marked  parallel  verticcd  fibres.  Between  these  fibres  are  numerous  vascular  open- 
ings. 

Development. — The  patella  is  developed  from  one  point  only.  In  a  few  rare  cases,  as 
Rudolphi  has  observed,  there  are  several  points.  The  ossification  of  the  patella  com- 
mences about  the  age  of  two  years  and  a  half 

The  Leg. 

The  Tibia  (fig.  52). 

The  tibia,  the  larger  of  the  two  bones  of  the  leg,  is  situated  between  the  femur,  which 
rests  upon  its  upper  end,  and  the  foot  on  which  it  is  supported.  Next  to  the  femur,  it 
is  the  largest  and  longest  bone  of  the  skeleton.  Its  upper  extremity  is  expanded  ;  the 
shaft  is  narrower,  and  of  a  triangular  prismatic  form.  The  lower  extremity  is  also  ex- 
panded, but  to  a  much  less  degree  than  the  upper.  The  smallest  part  of  the  tibia  does 
not  exactly  correspond  with  the  middle  of  the  shaft  as  in  the  femur,  but  at  the  junction 
of  the  lower  with  the  two  upper  thirds  ;  and  in  this  place  fractures,  produced  by  centre- 
coup,  are  most  frequent.  The  direction  of  the  tibia  is  vertical,  contrasting  thus  with  the 
femur,  which,  as  we  have  seen,  slants  obliquely  downward  and  inward.  In  individuals 
whose  thigh  bones  are  very  oblique,  the  tibife  have  a  direction  downward  and  outward. 
In  a  well-formed  skeleton,  the  two  tibiae  are  parallel. 

With  regard  to  its  axis,  the  tibia  presents  a  double  inflection,  so  that  the  upper  end  is 
turned  outward  and  the  lower  slightly  inward.  When  this  last  inclination  is  excessive, 
it  gives  rise  to  bowed  legs.  Lastly,  it  is  slightly  twisted  at  its  lower  part.*  Like  all 
long  bones,  it  is  divided  into  a  body  and  extremities. 

The  body  or  shaft  has  the  figure  of  a  triangular  prism ;  and  this  form,  which  is  observ- 
ed in  ahnost  all  long  bones,  is  in  none  so  marked  as  in  the  tibia.  We  have,  therefore, 
to  consider  three  surfaces  and  three  edges. 

The  internal  surface  (a,  fig.  53)  is  covered  at  the  upper  part  by  the  internal  lateral  lig- 
ament, and  by  an  aponeurotic  expansion  (called  patte  d^oie,f  or  goose'' s  foot) :  in  the  rest 
of  its  extent  it  is  immediately  under  the  skin.  This  superficial  situation  of  the  internal 
surface  partly  explains  the  facility  with  which  this  bone  may  be  broken  by  direct  violence, 
and  also  the  frequency  of  caries,  exostoses,  and  necrosis.  It  is  broad  above,  and  grad- 
ually diminishes  towards  the  lower  part.  Its  three  superior  fourths  look  inward  and 
fo'^ward  ;  its  lower  fourth  looks  directly  inward. 

The  external  surface  {b)  presents  in  a  great  part  of  its  extent,  but  especially  above,  a 
longitudinal  excavation,  the  depth  of  which  corresponds  to  the  size  of  the  tibialis  an- 

*  The  absence  of  an  antero-posterior  curvature  and  the  lateral  curves  in  opposite  directions,  together  with 
its  slight  torsion,  explains  the  great  solidity  of  this  bone. 

t  [This  patte  d'oie  consists  of  the  expansion  formed  by  the  tendons  of  the  sartorius,  gracilis,  and  semitendi- 
nogus  muscles.] 


THE  TIBIA. 


97 


ticus,  to  which  it  gii'es  attachment.    Inferiorly,  the  external  surface      Fig.5i.     Fig.sz. 

of  the  tibia  turns  forward  (d),  and  this  deviation  corresponds  with  the 

altered  direction  of  several  tendons,  which  are  placed  at  first  on  the 

outside  of  the  bone,  and  afterward  pass  in  front  of  it.     There  is,  in 

fact,  a  constant  reciprocity  between  alterations  in  the  direction  of 

bones,  and  changes  in  the  course  of  neighbouring  tendons. 

The  posterior  surface  is  also  broad  above,  and  progressively  dimin- 
ishes downward.  On  it  we  oh- 1  ve  near  the  upper  part,  I.  An  irreg- 
ular line,  running  obliquely  downward  and  inward ;  to  this  line  many 
of  the  deep-seated  muscles  on  the  back  of  the  leg  are  attached.  2. 
Above  this  line  a  triangular  surface  covered  by  the  popliteus  muscle, 
which  separates  it  from  the  popliteal  artery.  3.  Below  the  same 
line,  the  orifice  of  the  nutritious  canal,  which  runs  downward.  Into 
this  nutritious  canal,  which  is,  perhaps,  the  largest  of  any  in  the  long 
bones,  I  have  seen  a  nervous  twig  enter,  accompanying  the  nutri- 
tious artery.  4.  From  the  oblique  line  to  the  lower  end  of  the  tibia, 
the  posterior  surface  of  this  bone  is  smooth,  of  almost  uniform  di- 
ameter, and  divided  throughout  its  length  by  a  more  or  less  marked 
vertical  line. 

The  anterior  edge  (c  c)  is  placed  immediately  under  the  skin,  beneath 
which  it  may  be  readily  felt  ;*  its  lower  fourth  is  round  and  blunt,  the 
upper  three  fourths  are  sharp,  and  hence  it  has  been  called  the  crest  of 
the  tibia.  Its  upper  part  inchnes  somewhat  outward,  its  lower  part  in- 
ward. 

The  external  edge  (g  k)  gives  attachment  to  the  interosseous  liga- 
ment ;  it  is  bifurcated  below,  and  thus  forms  the  two  boundaries  of  an 
articular  cavity,  which  we  shall  notice  in  describing  the  lower  end  of  the  tibia.     The  «j- 
ternal  border  {f  I),  much  less  sharp  than  the  others,  affords  insertion  to  several  muscles. 

The  upper  or  femoral  extremity  (/  g)  of  the  tibia  is  at  least  double  tlie  size  of  the  lower, 
and  is  larger  in  a  transverse  direction  than  from  before  backward ;  on  it  we  observe 
two  concave  articular  surfaces,  of  an  oval  shape,  with  their  long  diameter  directed  from 
behind  forward.  They  have  been  improperly  denominated  condyles;  a  more  correct 
name  would  be  glenoid  cavities  of  the  tibia.  These  surfaces,  which  articulate  with  the  con- 
dyles of  the  femur,  are  not  perfectly  alike  ;  the  internal  is  longer,  narrower,  and  deeper 
than  the  external.  They  are  separated  by  a  pyramidal  eminence  surmounted  by  two 
sharp  tubercles.  This  eminence,  which  is  called  the  spine  of  the  tibia  (e),  is  nearer  the 
posterior  than  the  anterior  part  of  the  bone.  In  front  and  behind  this  spine  are  two 
rough  depressions,  which  give  attachment  to  the  crucial  ligaments.  The  glenoid  cavi- 
ties are  supported  by  two  considerable  enlargements,  called  tuberosities  of  the  tibia. 

The  internal  tuberosity  (/),  larger  than  the  external,  presents  behind  a  horizontal 
groove,  into  which  one  of  the  divisions  of  the  tendon  of  the  semi-membranosus  is  in- 
serted. The  external  tuberosity  (g),  smaller,  but  more  prominent  behind  than  the  internal, 
presents  at  its  back  part  a  small,  almost  circular  facette,  which  articulates  with  a  corre- 
sponding surface  on  the  fibula.  The  two  tuberosities  of  the  tibia  are  separated  behind  by  a 
considerable  excavation.  In  front  they  are  separated  by  a  triangular  surface,  pierced  by 
vascular  foramina,  and  terminating  below  in  an  eminence,  called  anterior  tuberosity  of  the 
tibia  (A).  This  tuberosity,  below  which  the  crest  of  the  bone  commences,  is  rough  and 
prominent  below,  where  it  gives  attachment  to  the  tendon  of  the  extensor  muscles  of 
the  leg,  ligamentum  patellcB,i  and  smooth  above,  where  it  is  separated  from  the  same  ten- 
don by  a  synovial  bursa.  A  projecting  line  runs  outward  from  this  tuberosity,  and  ter- 
minates above  in  a  tubercle,  which  is  very  prominent  in  some  individuals,  and  may  be 
easily  felt  under  the  skin.     It  gives  origin  to  part  of  the  tibialis  anticus. 

The  lower  or  tarsal  extremity  (Z  k)  of  the  tibia  is  almost  square,  having,  like  the  upper, 
its  greatest  diameter  transversely.  We  observe  on  it  a  quadrilateral  articular  cavity  (i), 
transversely  oblong,  broader  on  the  outside  than  on  the  inside,  and  divided  by  an  antero- 
posterior ridge,  into  two  unequal  parts.  It  articulates  wth  the  astragalus.  The  circum- 
ference of  this  extremity  presents,  1.  In  front,  a  convex  surface  (rf),  with  some  inequalities 
for  the  insertion  of  ligaments  ;  it  is  in  contact  with  the  extensor  tendons  of  the  toes.  2. 
Behind,  an  almost  plane  surface,  having  a  shallow  depression,  which  is  hardly  visible  in 
some  subjects,  forthe  tendon  of  the  long  flexor  of  the  great  toe,  and  which  must  not  be  con- 
founded with  an  oblique  groove,  situated  on  the  inner  side,  and  which  will  be  described 
with  the  internal  malleolus.  3.  On  the  outside,  a  triangular  cavity  (k),  broad  and  smooth 
below,  narrow  and  rough  in  its  two  upper  thirds,  which  articulates  with  the  fibula.    4.  On 


*  The  superficial  sitnation  of  the  antenor  edge  of  the  tibia  renders  it  a  good  guide  to  surgeons  in  the  diagiuv 
sis  and  coaptation  of  fractures  of  the  leg.  It  also  greatly  exposes  the  bone  to  injury  from  external  violence. 
It  is  not  uncommon  to  find  it  broken,  or,  as  it  were,  notched,  by  a  gun-shot. 

t  t  have  seen  this  tuberosity  so  large  that  several  practitioners,  not  familiar  in  such  anatomical  variettM, 
believed  it  to  be  an  exostosis,  and  had  placed  the  patient,  a  lad  of  14  years  of  age,  under  a  course  of  mercozial 
frictions. 

N 


90  OSTEOLOGY. 

the  inside,  a  thick  quadrilateral  process,  flattened  on  the  outside  and  the  inside,  and  call- 
ed the  internal  malleolus  (I).  This  eminence,  which  bends  inward,  forms  a  marked  prom- 
inence at  the  lower  and  inner  part  of  the  tibia.  When  the  posterior  surface  of  the  tibia 
is  laid  upon  a  horizontal  plane,  the  two  tuberosities  of  the  upper  end  of  the  bone  rest 
upon  that  plane,  while  the  internal  malleolus  advances  considerably  forward  ;  it  is  there- 
fore upon  a  plane  anterior  to  that  of  the  internal  tuberosity  of  the  tibia :  this  depends 
upon  the  torsion  of  the  lower  part  of  the  bone.  The  internal  surface  (l)  of  the  malleolus 
is  convex,  and  is  placed  immediately  under  the  skin  :  its  external  surface  forms  part  of 
the  inferior  articular  cavity  of  the  tibia.  Its  anterior  edge  is  rough,  and  gives  attachment 
to  ligamentous  fibres ;  its  posterior  edge,  which  is  thicker  than  the  anterior,  presents  a 
groove  running  obliquely  downward  and  inward,  and  sometimes  double,  along  which  the 
tendons  of  the  tibialis  posticus  and  flexor  longus  digitorum  pass.  The  base  of  the  mal- 
leolus, very  thick,  is  united  to  the  shaft  of  the  bone.  The  summit,  which  is  truncated 
and  slightly  notched,  gives  attachment  to  the  internal  lateral  ligament  of  the  ankle-joint. 

Connexions. — The  tibia  articulates  with  the  femur,  the  astragalus,  and  the  fibula ;  it 
articulates  also  with  the  patella,  but  indirectly  by  means  of  the  ligamentum  patellae. 

Internal  Structure. — The  shaft  consists  of  compact  tissue,  and  has  a  large  medullary 
canal.  The  two  extremities  are  spongy,  and  are  pierced  by  a  great  number  of  vascular 
foramina. 

Development;. — The  tibia  is  developed  from  three  points  ;  one  for  the  body,  and  two  for 
the  extremities.  Sometimes  there  are  four.  Beclard  once  saw  the  internal  malleolus 
developed  firom  a  separate  point.  The  ossific  point  of  the  shaft  is  the  first  to  make  its 
appearance  ;  it  commences  between  the  thirty-fifth  and  fortieth  day,  almost  at  the  same 
time  as  that  of  the  body  of  the  femur ;  sometimes  it  is  even  earlier,  as  in  one  case  ob- 
served by  myself  The  bony  germ  of  the  upper  extremity  makes  its  appearance  gen- 
erally towards  the  end  of  the  first  year  after  birth.  I  have  never  seen  it  before  birth. 
The  ossification  of  the  lower  extremity  commences  during  the  second  year.  The  inter- 
nal malleolus  is  formed  by  a  prolongation  of  this  extremity.  The  union  of  all  the  parts 
of  the  bone  is  not  finished  until  the  period  of  complete  development  of  the  body,  that  is, 
from  the  eighteenth  to  the  twenty-fifth  year ;  it  always  commences  with  the  lower  ex- 
tremity, which  is  the  last  to  become  bony.  It  is  of  importance  to  remark,  that  the  su- 
perior epiphysis  of  the  tibia  does  not  form  the  whole  of  the  upper  end  of  the  bone,  but 
only  a  sort  of  horizontal  plate  which  supports  the  articular  cavities  ;  and  the  same  is 
true  of  almost  all  articular  extremities.  It  should  also  be  observed,  that  the  anterior  tu- 
berosity of  the  tibia  is  formed  by  a  vertical  prolongation  of  the  plate  which  forms  the  su- 
perior epiphysis.  It  would  oppear,  that  in  some  subjects  this  anterior  tuberosity  has  a 
distinct  centre  of  development. 

The  Fibula  (fig.  53). 

The  fibula  or  perone  (from  irepovri)  is  so  named  because,  according  to  Sabatier,  it  has 
been  compared  to  a  sort  of  clasp  or  brace  in  use  among  the  ancients. 

In  order  to  understand  the  description  of  this  bone,  it  is  necessary  to  place  it  exactly 
in  the  position  which  it  occupies  in  the  skeleton.*  It  is  situated  on  the  outside  of  the 
tibia  below,  on  the  outside  and  to  the  back  of  the  same  bone  above.  It  is  as  long  as  the 
tibia,  but  is  extremely  slender ;  it  is>  indeed,  the  most  slender  of  all  the  long  bones,  and 
may  be  at  once  recognised  by  this  character.  Its  direction  is  vertical,  with  a  slight  in- 
chnation  outward  at  its  lower  part.  It  is  the  most  twisted  on  itself  of  all  the  long  bones, 
and  is  a  remarkable  exemplification  of  that  law  of  osteology,  viz.,  that  the  torsion  of 
bones  is  always  connected  with  the  changes  of  direction  of  tendons,  or  vessels.  It  is  divided 
into  a  body  and  two  extremities. 

The  body  has  the  form  of  a  triangular  prism.  In  order  rightly  to  comprehend  its 
shape,  it  is  necessary  to  be  aware  that  the  muscles  which  are  placed  on  its  external 
surface  above  turn  round  to  the  posterior  aspect  below,  from  which  it  is  easy  to  under- 
stand how  the  four  upper  fifths  of  the  external  surface  look  outward,  and  the  lower  fifth 
backward. 

The  external  surface  (n)  is  marked  by  a  deep  groove  which  runs  along  it,  and  gives  at- 
tachment to  the  peroneus  longus,  and  pcroneus  brevis.  The  lower  part,  which  is  turned  back- 
ward, is  smooth.  The  internal  surface  is  divided  into  two  unequal  parts  by  a  longitudi- 
nal ridge,  to  which  the  interosseous  ligament  is  attached.  The  portion  of  the  surface  in 
front  of  the  ridge  is  narrower  than  the  other,  being  in  some  subjects  not  more  than  two 
lines  in  breadth ;  it  gives  attachment  to  the  muscles  on  the  fore  part  of  the  leg :  the  por- 
tion beliind  the  ridge  is  larger,  and  gives  attaclunent  to  the  tibialis  posticus.  This  sur- 
face becomes  anterior  at  its  lower  part  (o). 

*  We  have  hitherto  deemed  it  unnecessary  to  indicate  the  position  in  which  each  bone  should  be  studied, 
Decause  a  glance  at  an  articulated  skeleton  would  suffice  to  enable  the  student  at  once  to  place  the  bones 
aright.  The  fibula,  however,  forms  an  exception,  on  account  of  its  remarkable  torsion.  In  order,  then,  to 
8t:5y  this  bone  conectly,  it  is  necessary  to  place  the  flattened  end  (u  »)  downward,  taking  care  that  the  artic- 
ular surface  on  that  part  be  turned  inward,  and  that  the  thin  edge  (u)  of  the  eminence  which  forms  this  Jow- 
"r  end  should  look  forward. 


v  >^^'  • 


THE    FOOT. 


99 


The  posterior  surface  of  the  fibula  is  narrow  above,  and  expanded  below,  where  it 
looks  inward,  and  terminates  by  a  rough  part,  to  which  ligaments  that  unite  it  to  the  tibia 
are  attached.  The  whole  of  this  surface  gives  attachment  to  muscles.  We  observe  on 
it  the  principal  nutritious  canal,  which  passes  obliquely  downward.  This  canal  is  some- 
times placed  on  the  internal  surface  of  the  bone. 

The  three  edges  participate  in  the  deviations  of  the  surfaces.  Thus,  the  miter  edge  (r) 
becomes  posterior  below  ;  the  anterior  edge  (s)  becomes  external,  and  is  bifurcated ;  the 
internal  edge  becomes  anterior,  and  after  being  thus  changed,  forms  the  continuation  of 
the  ridge  for  the  interosseous  ligament,  which  we  noticed  upon  the  inner  surface. 

All  the  edges  give  attachment  to  muscles  and  aponeurotic  processes,  and  are  remark- 
able for  their  prominence. 

The  superior  extremity  or  head  (t)  of  the  fibula  presents  an  articular  facette  (near  t\ 
slightly  concave,  which  unites  with  a  corresponding  surface  on  the  tibia :  on  the  outside 
are  some  irregular  impressions  for  the  insertion  of  the  biceps  muscle,  and  the  externa! 
lateral  Ugament  of  the  knee.  At  the  back  part  of  this  head  we  observe  the  styloid  pro* 
cess  of  the  fibula  (below  t)  for  the  tendon  of  the  biceps. 

The  lower  extremity  or  external  malleolus  (w  v)  passes  much  below  the  inferior  articu- 
lar surface  of  the  tibia ;  it  is  longer  and  thicker  than  the  internal  malleolus.  It  is  flat- 
tened on  the  outside  and  the  inside,  and  presents,  1.  An  external  surface  (uv),  convex 
and  sub-cutaneous.  2.  An  inlerTial  surface,  which  articulates  with  the  astragalus  hy 
means  of  a  facette,  which  completes  on  the  outside  the  sort  of  mortise  fgrjneci  by  tha 
union  of  the  lower  ends  of  the  tibia  and  fibula ;  below  and  behind  this  ^urfeioc  is  a,  deep, 
rough  excavation,  which  gives  attachment  to  a  ligament.  .3.^Aji  aut^erion  ^ige  (u)  for  the 
insertion  of  a  Ugament.  4.  A  posterior  edge  (c),  thicker,  ■jrarlied  by  a  superficial -groovG 
for  the  passage  of  the  tendons  of  the  peronei  muscles.  t&.  A  summit,  which  gives  airaclj 
ment  to  one  of  the  external  lateral  ligaments  of  the  ankle-jciu*^. 

Connexions. — The  fibula  forms  the  outer  part  of  rh*?  le?,  and  a^liculr.tes  with  the  tibia 
and  the  astragalus.  '     -  >    ^ 

Internal  Structure. — The  shaft  is  compact,  and  has  a  very  small  medullary  canal,  and 
the  extremities  are  spongy. 

Development. — The  fibiSa  is  developed  from  three  points  :  one  for  the  body,  and  one  for 
each  extremity.  The  osseous  point  of  the  body  appears  a  little  after  that  of  the  shaft  of 
the  tibia,  from  the  fortieth  to  the  fiftieth  day.  At  birth,  the  two  extremities  are  still  car- 
tilaginous. An  osseous  point  appears  in  the  lower  end  during  the  second  year ;  that  of 
the  upper  end  about  the  fifth.  The  extremities  are  united  to  the  shaft  of  the  bone  when 
the  development  is  completed,  viz.,  from  twenty  to  twenty-five  years  :  the  lower  end  is 
the  first  to  become  joined. 

The  Foot  {figs.  54,  55,  and  56). 

The  foot  is  the  part  of  the  lower  extremity  which  is  analogous  to  the  hand  in  the  up 
per.  They  are  both  but  varieties  of  the  same  type  of  organization,  with  certain  differ- 
ences which  have  reference  to  their  respective  uses.  In  the  foot,  for  example,  which  is 
intended  to  support  the  body,  the  conditions  necessary  for  solidity  are  principally  mani- 
fest, while  the  hand  is  chiefly  remarkable  for  the  mobility  of  its  parts. 

The  foot  is  composed  of  twenty-six  bones,  which,  by  their  imion,  form  three  distinct 
parts,  viz.,  1.  The  tarsus  (c  if,  fig.  54),  a  bony 
mass,  consisting  of  seven  pieces  closely  articu- 
lated ;  2.  The  metatarsus,  composed  of  five  sep- 
arate columns  {m  m",  figs.  54  and  55) ;  and,  3. 
The  toes,  formed  each  of  three  columns  (n  o  r), 
excepting  the  first,  or  most  internal,  which  has 
only  two  {71"  r"). 

The  size  of  the  foot  varies  in  different  indi- 
viduals. It  exceeds  the  hand  in  thickness  and 
length,  but  is  not  so  broad.  Its  direction  is 
horizontal  from  before  backward,  and  it  forms 
a  right  angle  with  the  leg,  differing  much  in 
this  respect  from  the  hand,  which  is  in  the 
same  line  as  the  forearm.  It  is  flattened  from 
above  downward,  is  hollow  below  {fig.  56),  nar- 
row behind,  where  it  is  of  considerable  height, 
and  thinner  and  broader  in  front,  at  which  part 
jilso  it  is  digitated.  It  presents,  1 .  A  superior 
or  dorsal  surface,  which  is  convex,  dorsum  pedis, 
( fig.  54) ;  2.  An  inferior  or  plantar  surface,  which 
is  concave  transversely,  and  likewise  in  the  an- 
tero-posterior  direction,  sole  of  the  foot  {fig.  55) ; 

3.  An  internal  or  tibial  edge  {fig.  56),  which  is  

very  thick,  and  corresponds  to  the  great  toe  ;  4.  An  external  or  fibular  edge,  which  corre- 


100  OSTEOLOGY. 

sponds  to  the  little  toe  ;  5.  A  ■posterior  extremity  or  heel ;  6.  An  anterxar  or  digital  exttemity. 
We  shall  describe  in  succession  the  tarsus,  the  metatarsus,  and  the  '.oes. 

The  Tarsus  {figs.  54,  55,  and  56). 
The  tarsus  is  an  analogous  structure  to  the  carpus,  but  differs  from  it  in  forming  the 
Pig^  56.  posterior  half  of  the  foot,  while  the  carpus 

only  constitutes  about  a  sixth  of  the  hand. 
Its  antero-posterior  diameter  surpasses  by 
more  than  double  its  transverse,  precisely 
the  opposite  of  what  obtains  in  the  carpus. 
It  resembles  a  vaulted  arch,  the  convexity 
of  which  (c  a  j,  fig.  56)  looks  upward,  and 
which  is  excavated  below  {d  i)  both  trans- 
versely and  from  before  backward.  The 
weight  of  the  leg  falls  upon  the  smnmit  of  this  arch.  This  form  of  the  foot  is  not  de- 
signed merely  for  securing  the  advantages  derived  from  the  mechanism  of  arches,  but  is 
especially  intended  to  afford  a  protecting  excavation  for  the  organs  which  could  not  with 
impunity  be  compressed  in  standing  and  progression.  The  posterior  and  free  extremity 
of  the  tarsus  is  narrow,  and  progressively  enlarges  forward. 

The  tarsus  is  composed  of  seven  bones,  disposed  in  two  rows.  The/r«^  or  tibial  raw 
iS  formed  b/'twp  bones  only,  the  os  calcis  (c)  and  the  astragalus  (a) ;  the  second  or  meta- 
tarsal row  cenoists  Qffiv& bones,  viz.,  the  scaphoid  (g),  the  cuboid  (/),  and  the  three  cune- 
iform bones  (i  j  I).  The  bo|ies.  of  the  first  row,  instead  of  being  placed  in  the  same  trans- 
verse line,  like  those  of  the,  flust,  row  of  the  carpus,  rest  one  upon  the  other.  The  astrag- 
iilus'is  the  oniy  JJipne /)f  the  tarsus  which  enters  into  the  formation  of  the  ankle-joint. 

' ' '  ■  "  "'■'^o  .Fiiist  ,cri  'J!iJ)ial  Row  of  the  Tarsus. 
"  "  ■  ♦  The  Astragalus  [a). 
The  astragalus  is  placed  below  the  tibia,  above  the  os  calcis,  on  the  inside  of  the  mal- 
leolar extremity  of  the  fibula,  and  behind  the  scaphoid ;  it  is  irregularly  cuboid  in  its  fig- 
ure, is  the  second  largest  bone  of  the  tarsus,  and  heis  six  surfaces :  1.  The  superior  oi 
tibial  surface  (a,  fig.  54)  is  articular,  and  shaped  like  a  trochlea  or  pulley,  which  fits  ex- 
actly to  the  lower  surface  of  the  tibia.  In  front  and  behind  the  trochlea  are  inequalities 
for  the  attachment  of  ligaments.  2.  The  inferior  or  calcaneal  surface  (a,  fig.  55)  presents 
two  facettes,  separated  by  a  very  deep  furrow,  running  obliquely  backward  and  inward, 
and  broadest  in  front,  which  gives  insertion  to  a  ligament.  The  facette  behind  the 
groove  is  the  larger ;  it  is  concave  and  oblong  in  the  same  direction  as  the  groove.  The 
facette  in  front  is  flat,  and  often  divided  into  two  smaller  surfaces.  Both  articulate  with 
the  OS  calcis.  3.  The  internal  lateral  surface  {fig.  56)  is  articular  for  a  considerable  por- 
tion of  its  upper  part,  and  corresponds  to  the  internal  malleolus  ;  below,  there  is  a  rough 
depression,  which  gives  attachment  to  the  internal  lateral  ligament  of  the  ankle-joint. 
4.  The  exterTud  lateral  surface  is  triangular,  like  the  corresponding  surface  of  the  external 
malleolus,  with  which  it  articulates.  It  should  be  remarked,  that  both  the  lateral  articu- 
lar surfaces  of  the  astragalus  are  continuous  with  the  trochlea  or  upper  surface,  without 
mterruption.  5.  The  anterior  or  scaphoid  surface  is  convex,  and  has  been  called  the  head 
of  the  astragalus ;  it  is  articular,  and  continuous,  below,  with  the  anterior  facette  of  the 
lower  surface  of  the  bone  already  described.  This  head  is  supported  by  a  contracted 
portion,  or  neck  (i,  fig.  54  and  56),  to  which  ligaments  are  attached.  6.  The  posterior 
surface  is  very  small ;  it  consists  simply  of  a  groove,  slanting  downward  and  inward, 
along  which  the  tendon  of  the  flexor  longus  poUicis  pedis  glides. 

The  Os  Calcis  (c). 

The  OS  calcis,  or  calcaneum,  situated  below  the  astragalus,  and  at  the  lower  and  back 
part  of  the  foot,  is  the  largest  bone  of  the  tarsus.  Its  form  is  irregularly  cuboid,  with 
the  greatest  diameter  from  before  backward ;  it  is  flattened  transversely.  Its  size  and 
its  length  have  reference  to  the  double  ofl5ce  which  it  serves,  of  transmitting  the  weight 
of  the  body  to  the  ground,  and  of  acting  as  a  lever  for  the  extensor  muscles  of  the  foot. 
I  should  remark,  that  its  large  posterior  extremity  forms  the  heel  (d,  figs.  55,  56),  the 
horizontal  direction  of  which,  in  man,  is  one  of  the  most  advantageous  arrangements  for 
the  vertical  position  of  the  body. 

The  OS  calcis  has  six  surfaces  :  1.  The  superior  surface  {fig.  54)  presents,  in  front,  two, 
or  often  three,  articular  facettes,  which  correspond  with  those  on  the  lower  surface  ol 
the  astragalus.  The  posterior  facette  is  the  larger,  convex,  and  separated  from  the  an 
terior  by  a  groove,  which  is  shallower  than  the  corresponding  one  of  the  astragalus,  but 
follows  the  same  direction  backward  and  inward.  The  whole  of  the  non-articular  por- 
tion of  this  surface  projects  behind  the  astragalus  ;  it  is  flattened  on  the  sides,  and  slight- 
ly concave  from  before  backward.  Its  length  varies  in  different  individuals,  and  is  tho 
cause  of  the  varieties  in  the  projection  of  the  heel.     2.  Tlie  lower  oi  plantar  surface  {fig 


THE    CUBOID    AND    SCAPHOID  BONES.  101 

55)  is  rather  an  edge  than  a  true  surface ;  it  is  directed  obliquely  upward  and  forward. 
We  observe  here,  at  the  back  part,  two  tuberosities,  the  internal  of  which  is  much  larger 
than  the  external ;  both  serve  as  places  of  insertion  for  muscles,  but  their  principal  use 
is  to  support  the  weight  of  the  body  behind,  and  they  essentially  constitute  the  heel  (d. 
Jig.  56)  in  the  human  subject.  3.  The  external  surface  is  superficial,  which  accounts  for 
the  frequency  of  injuries  of  this  bone  on  its  outside,  and  explains,  also,  the  ])ossibility  of 
reaching  it  with  surgical  instruments.  It  is  convex,  and  narrow  in  front,  where  it  pre- 
sents two  superficial  grooves  separated  by  a  tubercle  (s,  figs.  54  and  55).  These  grooves 
afford  a  passage  to  the  tendons  of  the  peroneus  longus  and  brevis.  On  the  anterior  and 
superior  part  of  this  surface  we  find,  also,'tinother  tubercle,  which  is  a  guide  to  the  sur- 
geon in  the  partial  amputation  of  the  foot  recommended  by  Chopart.  4.  The  internal  sur- 
face {fig.  56)  is  deeply  grooved  for  the  passage  of  several  tendons,  and  also  for  the 
nerves  and  vessels  which  are  distributed  to  the  sole  of  the  foot.  It  presents,  in  front 
and  above,  a  projecting  eminence,  like  a  blunt  hook,  in  a  shallow  groove,  below  which 
the  tendon  of  the  flexor  longus  pollicis  pedis  glides.  This  eminence  has  been  called 
the  small  process  of  the  os  calcis  (e,  fig.  56),  also  sustentaculum  tali,  because  the  anterior 
and  internal  articular  surface,  which  supports  the  astragalus,  is  on  its  upper  part.  5. 
The  anterior  or  cuboid  surface  is  the  smallest.  It  is  concave  from  above  downward,  and 
articulates  with  the  cuboid.  It  is  surmounted  on  the  inside  by  a  short  projection,  direct- 
ed horizontally  forward,*  above  which  the  third  articular  surface  for  the  astragalus  is 
situated  when  it  exists.  The  whole  portion  of  the  os  calcis  which  supports  the  anterior 
or  cuboid  surface  bears  the  name  of  great  process  of  the  os  calcis  {t,figs.  54  and  55).  6. 
The  posterior  surface  is  shaped  like  a  triangle,  with  the  base  downward  ;  its  lower  part 
is  rough  and  irregular,  and  gives  attachment  to  the  tendo  Achillis,  the  upper  part,  over 
which  the  same  tendon  glides,  being  smooth  and  polished  like  ivory. 

Second  Row  of  the  Tarsus. 
The  bones  of  the  second  row  are  five  in  number :  on  the  outside  it  is  formed  by  the 
cuboid  alone,  but  on  the  inside  it  is  subdivided  into  two  secondary  rows  ;  a  posterior, 
formed  by  the  scaphoid  ;  and  an  anterior,  composed  of  the  three  cuneiform  bones.  This 
subdivision  of  the  inner  portion  of  the  tarsus,  by  multiplying  the  articulations,  has  the 
effect  of  diminishing  the  violence  of  shocks,  or  of  pressure  upon  the  foot,  especially  on 
the  inner  side,  to  which  they  are  principally  applied. 

The  Cuboid  Bone  [ffigs.  54  and  55). 
Tho  cuboid,  which  ranks  £is  the  third  bone  of  the  tarsus  in  point  of  size,  is  situated  at  the 
outside  of  the  foot,  and  appears  like-a  continuation  of  the  great  process  of  the  os  calcis.  It 
is  more  regularly  cuboid  than  any  of  the  other  tarsal  bones,  and  has  six  surfaces  :  1.  The 
upper  or  dorsal  surface  {fig.  54)  is  covered  by  the  extensor  brevis  digitorum  pedis,  and 
looks  somewhat  outward.  2.  The  lower  or  plantar  surface  {fig.  55)  presents  on  its  fore  part 
a  deep  groove  (/),  running  obliquely  inward  and  forward,  for  the  tendon  of  the  peroneous 
longus.  Behind  this  groove,  the  posterior  lip  of  which  is  very  prominent,  are  impres- 
sions for  the  ligament  which  connects  the  cuboid  and  the  os  calcis.  3.  The  posterior  or 
calcaneal  surface  is  sinuous,  directed  obliquely  inward  and  backward,  and  adapted  to  the 
OS  calcis  in  such  a  way  that  there  is  a  mutual  reception  of  the  surfaces  of  the  two  bones. 
At  the  inside  of  this  surface,  we  observe  a  process  which  is  directed  inward  and  back- 
ward, and  strengthens  the  union  with  the  os  calcis.  It  occasionally  becomes  an  obstacle 
to  the  disarticulation  of  the  foot,  after  Chopart's  method.  4.  The  anterior  or  metatarsal 
surface  looks  obhquely  inward  and  forward  ;  it  articulates  with  the  fourth  and  fifth  meta 
tarsal  bones.  5.  The  internal  surface  articulates  with  the  third  cuneiform  bone,  and  fre- 
quently also  with  the  scaphoid ;  it  presents,  besides,  some  impressions  for  the  insertiop. 
of  ligaments.  6.  The  external  surface  is  rather  an  edge;  its  extent  from  before  back- 
ward scarcely  equals  half  the  length  of  the  internal  surface.  We  observe  on  it  the  com- 
mencement of  the  groove  for  the  tendon  of  the  peroneus  longus. 

The  Scaphoid  {g,Jigs.  54,  55,  and  56). 
The  scaphoid  or  navicular  hone,  so  named  from  its  supposed  resemblance  to  a  boat,  is 
situated  on  the  inner  side  of  the  tarsus ;  it  is  flattened  from  before  backward,  and  is 
thicker  above  than  below,  irregularly  elliptical,  with  the  long  diameter  placed  transverse- 
ly. It  has  two  surfaces  and  a  circumference  :  1.  The  posterior  surface  is  concave,  and 
receives,  thougn  incompletely,  the  head  of  the  astragalus.  2.  The  anterior  surface  pre- 
sents three  articular  facettes,  which  correspond  to  the  three  cuneiform  bones.  3.  The 
circumference  is  convex  above,  inclined  inward,  and  rough  for  ligamentous  insertions.  It 
is  much  smaller  below,  where  also  it  gives  attachment  to  ligaments.  On  the  i?iside  it 
presents,  at  its  lower  part,  a  large  process,  process  of  the  scaphoid  (at  g),  which  may  be 
easily  felt  under  the  skin,  and  serves  as  a  guide  in  performing  Chopart's  amputation. 
This  process  gives  attachment  to  the  tendon  of  the  tibialis  posticus.     It  is  frequently 

*  This  small  prolongation,  which  might  be  called  imaZi  anterior  process  of  the  os  calcis,  in  contradistinction 
to  the  one  on  the  internal  surface  already  mentioned,  merits  notice  in  the  performance  of  Chopart's  operation. 


102  OSTEOLOGY. 

very  large,  and  may,  and,  indeed,  has  been  mistaken  for  an  exostosis  of  the  bone.  On 
the  outside  the  circumference  is  irregular,  gives  attachment  to  some  hgamentous  fibres, 
and  often  presents  a  small  surface  which  articulates  with  the  cuboid :  this  surface  is 
continuous  with  the  facettes  for  the  three  cuneiform  bones. 

The  Three  Cuneiform  Bones. 
These  bones,  so  named  from  their  shape,  are  three  in  number:  they  are  called ^rsf, 
second,  and  third,  counting  from  the  inside  of  the  foot.     Tliey  are  also  distinguished  by 
their  size,  into  the  great,  middle-sized,  and  small.* 

The  First  Cuneiform  Bone  (t,  figs.  54,  55,  and  56). 
The  first  or  internal  cuneiform  bone  is  the  largest.  It  is  placed  on  the  inside  of  the 
others,  in  front  of  the  scaphoid,  and  behind  the  first  metatarsal  bone.  It  is  shaped  like 
a  wedge  with  the  base  below,  which  is  precisely  contrary  to  what  obtains  with  the  other 
two.  We  observe  oa  it,  1.  An  internal  surface  {fig.  56),  which  is  subcutaneous,  and 
forms  part  of  the  inner  edge  of  the  foot.  2.  An  external  surface,  which  presents  an  an- 
gular articular  facette  for  union  with  the  second  cuneiform  bone  behind,  and  the  second 
metatarsal  bone  before ;  the  non-articular  portion  of  the  external  surface  of  the  first 
cuneiform  bone  is  rough,  and  gives  attachment  to  ligaments.  3.  A  posterior  surface, 
which  is  concave,  and  articulates  with  the  most  internal  and  largest  facette  on  the  an- 
terior surface  of  the  scaphoid.  4.  An  anterior  or  metatarsal  surface,  which  is  plane,  or, 
rather,  shghtly  convex,  of  a  semilunar  form,  the  convexity  being  to  the  inside,  and  the 
greatest  diameter  vertical ;  it  is  broad  below  and  narrow  above,  and  articulates  with 
,  the  first  metatarsal  bone.  5.  An  inferior  surface  {fig.  55),  which  forms  the  base  of  the 
wedge  ;  it  is  rough,  with  a  tubercle  behind  for  the  attachment  of  the  tibialis  anticus.  6. 
An  upper  part  {fig.  54),  which  forms  the  point  of  the  wedge ;  it  is  an  angular  border, 
running  forward  and  upward,  and  thicker  in  front  than  behind,  where  it  contributes  to 
form  the  convexity  of  the  foot. 

The  Second  or  Middle  Cuneiform  Bone  {j,fig.  54,  55,  and  56). 
The  second  coneiform  bone  is  the  smallest  of  the  three  :  it  ^  placed  between  the  two 
others,  and  corresponds  to  the  scaphoid  behind,  and  the  second  metatarsal  bone  in  front. 
The  wedge  wliich  it  represents  has  the  base  turned  upward  ;  its  length  from  behind  for- 
ward is  very  inconsiderable.  It  presents,  1.  An  internal  surface,  which  is  triangular,  and 
articulates  with  the  first  cuneiform  bone  :  2.  An  external  surface,  which  articulates  with 
the  third  or  external  cuneiform  bone  :  3.  A  posterior  or  scaphoid  surface,  which  is  concave, 
and  articulates  with  the  middle  facette  on  the  anterior  surface  of  the  scaphoid :  4.  An 
anterior  or  metatarsal  surface,  which  is  triangular,  and  nan'ower  than  the  posterior ;  it 
articulates  with  the  second  metatarsal  bone  :  5.  A  superior  surface  {fig.  54),  or  lase  of 
the  wedge,  which  is  irregularly  square,  and  rough  for  the  attachment  of  ligamentous 
fibres :  6.  An  apex  {fig.  55),  which  is  very  thin,  and  gives  attachment  to  some  hgaments. 

The  Third  or  External  Cuneiform  Bone  {I,  figs.  64  and  55). 

This  bone,  which  is  the  third  as  regards  position,  and  the  second  in  point  of  size,  has, 
like  the  preceding,  the  form  of  a  wedge  with  the  base  turned  upward.  Its  internal  sur- 
face articulates  behind  with  a  corresponding  surface  on  the  preceding  bone,  and  in  front 
with  the  second  metatarsal.  This  last  portion  completes  the  kind  of  recess  or  mortise 
into  which  the  head  of  the  second  metatarsal  bone  is  received ;  its  inner  side  being 
formed  by  the  first  cuneiform  bone,  and  the  bottom  by  the  second.  The  external  surface 
articulates  with  the  cuboid :  the  posterior  surface  is  continuous  with  the  two  lateral  ones, 
and  articulates  with  the  most  external  of  the  three  facettes  on  the  scaphoid  :  the  ante- 
rior surface  is  triangular,  and  articulates  with  the  end  of  the  third  metatarsal  bone  :  the 
base  {fig.  54)  is  rough,  and  forms  part  of  the  convexity  of  the  foot :  the  apex  {fig.  55)  is 
more  obtuse  than  the  same  part  of  the  second  cuneiform  bone,  and  passes  considerably 
below  it. 

Structure  of  the  Banes  of  the  Tarsus. — The  bones  of  the  tarsus  present  the  structure 
common  to  all  short  bones,  viz.,  a  mass  of  spongy  tissue  surrounded  by  a  layer  of  com- 
pact substance.  I  have  remarked,  that  in  some  cases  of  white  swelling  of  the  ankle- 
joint,  the  OS  calcis  contained  in  its  interior  a  cavity  analogous  to  the  medullary  canal  of 
long  bones.     This  cavity,  however,  must  be  looked  upon  as  Edtogether  abnormal. 

Development  of  the  Tarsal  Bones. — ^With  the  exception  of  the  os  calcis,  which  has  two 
osseous  germs,  all  the  bones  of  the  tarsus  are  developed  from  single  points.  The  os 
calcis  first  becomes  ossified.  A  bony  nodule  appears  in  the  centre  of  its  cartilage,  about 
the  middle  of  the  sixth  month  of  foetal  life,  according  to  most  osteogonists  ;  in  the  fifth, 
or  even  the  fourth  month,  according  to  others.  It  is  placed  much  nearer  the  anterior 
than  the  posterior  extremity  of  the  future  bone.  Another  osseous  germ  is  formed  in  the 
posterior  extremity  of  the  os  calcis,  from  the  eighth  to  the  tenth  year,  and  is  much 
thicker  at  its  lower  than  at  its  upper  part.     The  astragalus  is  developed  from  one  point, 

*  Also,  by  position,  into  internal,  middle,  and  external. 


THE   METATARSUS.  103 

which  appeara  from  the  fifth  to  the  sixth  month  of  intra-uterine  life.  According  to  Bfe- 
clard,  the  cuboid  is  not  ossified  until  some  months  after  birth  ;  I  have  observed  the  pro- 
cess to  be  already  commenced  in  a  foetus  at  the  full  term.  Meckel  says  that  it  begins 
after  the  eighth  month  of  foetal  life.  Blumenbach,  on  the  contrary,  makes  the  time  of 
its  ossification  a  year  and  a  half,  or  two  years  after  birth ;  and  Albinus,  who  has  been 
followed  in  this  respect  by  the  generality  of  anatomists,  affirms  that  in  the  foetus  at  the 
full  period,  all  the  bones  of  the  tarsus,  excepting  the  os  calcis  and  the  astragalus,  still  re- 
main cartilaginous. 

The  cuneiform  bones  are  developed  in  the  following  order :  The  first  is  ossified  to 
wards  the  end  of  the  first  year ;  the  second  and  the  third  appear  almost  simultaneously 
about  the  fourth  year ;  the  os  calcis  being  the  only  bone  of  the  tarsus  which  has  more 
than  one  point  of  ossification,  is  also  the  only  bone  in  which  we  have  to  examine  the  or 
der  of  union.    The  two  points  which  form  it  are  not  united  until  the  fifteenth  year. 

The  Metatarsus  {m  m'^figs.  54,  55,  and  56). 

The  metatarsus  forms  the  second  portion  of  the  foot.  Like  the  metacarpus,  its  anal 
ogous  part  in  the  hand,  it  consists  of  five  long  bones,  parallel  to  each  other,  forming  a 
sort  of  quadrilateral  grating,  the  intervals  of  which,  called  interosseous  spaces,  are  in- 
creased by  the  disproportion  between  the  ends  and  the  shafts  of  the  bones.  The  meta- 
tarsus presents,  1.  An  inferior  or  plantar  surface  {fig.  55),  with  a  marked  transverse  con- 
cavity ;  2.  A  superior  or  dorsal  surface  {fig.  54),  which  is  convex^  and  answers  to  the 
back  of  the  foot ;  3.  An  internal  or  tibial  edge  (m',  fig.  56),  which  is  very  thick,  and  cor- 
responds to  the  great  toe  ;  4.  An  external  or  fibular  edge,  which  is  thin,  and  corresponds 
to  the  little  toe  ;  5.  A  posterior  or  tarsal  extremity,  which  presents  a  waved  articular  line ; 
6.  An  anterior  or  digital  extremity,  presenting  five  heads  flattened  on  the  sides,  which  as- 
sist in  forming  five  separate  articulations.  The  bones  of  the  metatarsus  have  certain 
characters  which  distinguish  them  from  all  others,  besides  some  peculiar  marks  by  which 
they  may  be  known  from  each  other,  and  from  the  metacarpal  bones,  with  which  they 
have  many  analogies. 

General  Characters  of  the  Metatarsal  Bones. 
The  metatarsal  bones  belong  to  the  class  of  long  bones,  both  in  shape  and  structure. 
Each  consists  of  a  body  and  two  extremities.  The  body  is  prismatic  and  triangular,  and 
sUghtly  curved,  with  the  concavity  below.  Two  of  its  surfaces  are  lateral,  and  corre- 
spond to  the  interosseous  spaces ;  the  third,  so  narrow  that  it  resembles  an  edge,  is  on 
the  dorsum  of  the  foot.  Two  of  the  edges  are  lateral ;  the  third  is  below,  on  the  plantar 
aspect  of  the  foot. 

The  posterior  or  tarsal  extremity  is  much  expanded,  and  presents  five  surfaces,  two  of 
which  are  non-articular,  and  three  articular.  Of  the  two  non-articular  surfaces,  one  is  su- 
perior, and  the  other  inferior ;  both  give  attachment  to  ligaments.  Of  the  three  articu- 
lar surfaces,  one  is  posterior,  that  is,  on  the  extremity  of  the  bone ;  in  general  it  is  tri- 
angular, and  articulates  with  a  corresponding  surface  on  one  of  the  tarsal  bones.  The 
other  two  are  lateral,  partly  articular,  and  partly  non-articular.  The  articular  surfaces 
are  small,  and  often  consist  of  more  than  one  ;  they  join  the  contiguous  metatarsal  bones. 
The  tarsal  extremity  is  wedge-shaped ;  the  upper  or  dorsal  surface  being  very  broad, 
represents  the  base  of  the  wedge ;  the  lower  surface,  being  narrow,  forms  the  point. 

The  anterior  or  digital  extremity  presents  a  head  or  condyle,  flattened  on  the  sides,  and 
oblong  from  above  downward ;  the  articular  surface  extends  much  farther  on  the  lower 
aspect,  or  in  the  direction  of  flexion,  than  on  the  upper,  or  the  direction  of  extension. 
On  the  inside  and  outside  of  the  condyle  there  is  a  depression,  and  a  projection  behind 
it  for  the  lateral  ligament  of  the  joint. 

Characters  of  the  different  Metatarsal  Bones. 

The  first  or  metatarsal  bone  of  the  great  toe  (m',  figs.  54,  55,  56)  is  remarkable  for  its 
great  size.  It  is  the  only  one  which,  in  this  respect,  resembles  the  tarsus  ;  its  body  is 
shaped  like  a  triangular  prism ;  its  digital  extremity  is  marked  on  the  plantar  aspect  by 
a  double  furrow  for  two  sesamoid  bones  (*,  fig.  56).  (Vide  Articulation  of  the  Foot.)  Its 
tarsaL  extremity  presents  a  semilunar  concave  surface,  with  its  greatest  diameter  verti- 
cal, which  articulates  with  the  internal  cuneiform  bone.  There  is  no  articular  surface 
on  the  circumference  of  the  first  metatarsal  bone.  In  this  point  it  resembles  the  first 
metacarpal  bone,  and  by  this  and  its  great  size  it  is  distinguished  from  all  the  others. 

The  fifth  metatarsal  bone  (m,  fig.  54,  55)  is  the  shortest  after  the  first ;  it  has  only  one 
lateral  articular  face  on  its  tarsal  extremity.  On  the  opposite  side  of  this  extremity, 
viz.,  on  the  outside,  we  observe  a  large  process,  process  of  the  fifth  inetatarsal  bone,  shaped 
like  a  triangular  pyramid,  and  directed  obliquely  backward  and  outward,  into  which  the 
peroneus  brevis  is  inserted.  This  process  may  be  easily  felt  under  the  skin,  and  serves 
as  a  guide  in  the  partial  amputation  of  the  foot  at  the  tarso-metatarsal  articulation. 
Another  charact^iristic  of  the  fifth  metatarsal  bone  is  the  great  obliquity  outward  and 
backward  of  the  %rticular  face  on  its  posterior  extremity. 


104  OSTEOLOGY. 

The  second,  third,  and  fourth  metatarsal  bones  are  distinguished  from  each  other  by 
the  following  characters. 

The  second  is  the  longest,  and  also  the  largest  after  the  first ;  it  articulates  with  the 
three  cuneiform  bones  by  its  posterior  extremity,  which  is  dovetailed  with  them.  The 
third  and  the  fourth  metatarsal  bones  are  of  almost  equal  length ;  their  apparent  difference 
in  an  articulated  foot  depends  chiefly  on  the  fact  that  the  articulation  of  the  fourth  with 
the  cuboid  is  on  a  plane  posterior  to  that  of  the  third  with  the  external  cuneiform  bone. 
Lastly,  they  may  be  known  from  each  other  by  the  presence  of  two  surfaces,  on  the  in- 
side of  the  posterior  extremity  of  the  fourth  metatarsal ;  one  being  for  the  external  cu- 
neiform bone,  and  the  other  for  the  third  metatarsal  bone. 

Development. — The  metatarsal  bones  are  developed  from  two  points  ;  one  for  the  body, 
and  one  for  the  anterior  or  digital  extremity.  The  first  metatarsal  bone  is  the  only  ex- 
ception to  this  rule,  for  its  epiphysary  point  is  situated  at  the  posterior  extremity.*  The 
osseous  point  of  the  body  appears  first  during  the  third  month,  according  to  the  majority 
of  authors,  but  about  the  forty-fifth  day,  according  to  the  observations  of  Blumenbach  and 
Beclard.  It  is  completely  developed  in  the  foetus  at  the  full  period.  The  epiphysary 
point  makes  its  appearance  during  the  second  year.  The  union  of  these  parts  does  not 
take  place  until  the  eighteenth  or  nineteenth  year,  and  is  not  simultaneous  in  all  the 
bones  of  the  metatarsus.  The  epiphysis  of  the  first  metatarsal  bone  is  the  first  to  unite 
with  the  body.  An  interval  of  a  year  sometimes  intervenes  between  the  union  of  this 
epiphysis  and  those  of  the  other  four  metatarsal  bones. 

The  Toes  [n  o  r,  n  r,  Jigs.  54,  55). 

The  resemblance  between  the  phalanges  of  the  fingers  and  those  of  the  toes  is  so  com- 
plete, that  we  cannot  do  better  than  refer  to  the  description  already  given  of  the  former 
for  details  respecting  the  latter.  At  the  same  time,  it  should  be  remarked,  that  the  pha- 
langes of  the  toes  appear,  as  it  were,  atrophied,  or  stinted  in  growth,  when  compared 
with  those  of  the  fingers,  excepting  the  great  toe,  which,  in  all  its  parts,  preserves  the 
large  dimensions  of  the  inner  side  of  the  foot. 

The  first  or  metatarsal  phalanx  {n  to  n')  resembles  closely  the  metacarpal  phalanx  of 
the  fingers.  The  middle  phalanx  (o)  is  remarkably  small  and  short ;  it  would  almost  ap- 
pear to  consist  of  the  extremities  alone,  the  body  being  absent.  At  first  sight  it  might 
be  t£iken  for  a  pisiform  bone,  or,  rather,  for  one  of  the  pieces  of  the  coccyx  ;  but  the 
presence  of  anterior  and  posterior  articular  faces  is  sufficient  to  mark  the  distinction. 

The  ungual  phalanges  (r  r')  of  the  toes  resemble  in  form,  but  are  much  smaller  than 
the  corresponding  parts  of  the  fingers.  This  remark,  however,  only  applies  to  the  last 
four,  for  the  ungual  phalanx  of  the  great  toe  is  in  size  at  least  double  that  of  the  thumb. 
I  cannot  conclude  this  description  without  remarking,  that  the  articular  surface  of  the 
posterior  extremity  of  the  metatarsal  phalanges,  as  well  as  of  the  anterior  extremity  of 
the  metatarsal  bones,  is  prolonged  farther  upward  than  the  corresponding  surfaces  on 
the  metacarpal  bones  and  phalanges  of  the  fingers  ;  this  arrangement  allows  a  greater 
extension  of  the  toes,  and  is  an  important  element  in  the  mechanism  of  progression. 

Development. — The  first,  second,  and  third  phalanges  are  developed  from  two  points 
of  ossification  ;  one  for  the  body,  and  one  for  the  metatarsal  extremity.  The  epiphysary 
points  of  the  second  and  third  phalanges  are  so  small,  that  their  existence  has  been 
doubted  by  many  anatomists.  The  osseous  points  of  the  bodies  of  the  first  phalanges 
are  much  later  in  appearing  than  those  of  the  metatarsal  bones,  not  being  visible,  in 
general,  until  from  the  second  to  the  fourth  month ;  the  first  phalanx  of  the  great  toe  is 
an  exception,  its  ossification  concmiencihg  from  the  fiftieth  to  the  sixtieth  day.  The 
epiphysary  point  of  the  first  phalanges  does  not  appear  until  the  fourth  year.  The  bodies 
of  the  second  phalanges  are  ossified  almost  at  the  same  time  as  those  of  the  first ;  the 
epiphysary  point  of  their  posterior  extremity  is  not  visible  until  from  the  sixth  to  the  sev- 
enth year.  The  bodies  of  the  third  phalanges  are  ossified  before  those  of  the  second  and 
the  first ;  an  osseous  point  appears  in  them  about  the  forty-fifth  day,  excepting  in  the  lit- 
tle toe,  where  it  is  much  later.  The  ungual  phalanx  of  the  great  toe  is  remarkable  as  be- 
ing ossified  before  all  the  other  phalanges  of  the  toes.  It  is  developed  from  a  point  which 
does  not  occupy  the  centre,  but  the  summit  of  the  phalanx.  The  epiphysary  point  of  the 
posterior  extremity  appears  about  the  fifth  year  in  the  great  toe,  and  about  the  sixth  year 
in  the  othei  four.  The  epiphysary  points  of  the  phalanges  are  not  united  to  the  bodies 
until  the  age  of  seventeen  or  eighteen  years. 

General  Development  of  the  Inferior  Extremity. 
The  most  characteristic  feature  of  the  lower  extremity  in  the  foetus  is  the  comparative 
Sateness  of  its  development,  which  is  most  remarkable  at  the  early  periods.    We  have 

*  This  exception  corresponds  entirely  with  that  observed  in  the  hand,  and  renders  the  analogy  between  the 
metatarsal  bone  of  the  great  toe  and  the  metacarpal  of  the  thumb  extremely  close  ;  for  the  same  reason,  both 
of  these  bones  resemble  tke  first  phalanges  of  the  fingers.  I  may  add,  that,  in  some  subjects,  it  has  appeared 
to  me  that  there  was  a  very  thin  epiphysary  point  at  the  digital  extremity  of  this  bone,  which  soon  united  tn 
the  body 


COMPARISON    Oi'    THE    EXTREMITIES.  106 

already  stated  the  periods  at  which  each  point  of  ossification  appears  in  the  diiferent 
bones,  and  the  times  at  which  they  are  united,  and  it  now  only  remains  for  us  to  point 
out  some  peculiarities  of  development  which  have  not  been  included  in  the  description 
of  the  bones. 

From  the  observations  of  Bichat,  it  is  generally  admitted  that  the  neck  of  the  femur 
in  the  foetus  and  the  newly-born  infant  is  proportionally  shorter  than  in  the  adult,  and 
forms  ahnost  a  right  angle  with  the  shaft  of  the  bone  ;  that  the  body  of  the  femur  is  al- 
most straight ;  and  that  its  extremities  are  proportionally  much  larger  than  they  become 
subsequently.  As  we  before  observed  with  regard  to  the  upper  extremities,  all  these 
assertions  are  at  variance  with  the  results  of  our  observations.  The  same  reflections 
apply  equally  to  the  bones  of  the  leg,  the  torsion  of  which  we  believe  to  exist  to  the  same 
degree  in  the  foetus  and  in  the  new-bom  infant  as  in  the  adult. 

After  birth,  the  development  of  the  lower  limbs  proceeds  more  rapidly  than  that  of  the 
upper,  and  the  final  proportions  are  not  attained  until  the  age  of  puberty.  In  the  aged, 
the  phalanges  of  the  toes  are  often  anchylosed ;  but  this  union,  like  the  dislocations  of 
the  toes,  and  some  deformities  of  the  tarsus  and  metatarsus,  are  the  results  of  pressure 
upon  the  foot  occasioned  by  tight  shoes,  and  the  more  or  less  complete  immobility  in 
which  the  parts  are  maintained.* 

Comparison  of  the  Superior  and  Inferior  Extremities. 

We  have  hitherto  omitted  the  applications  of  that  species  of  comparative  anatomy  by 
which  different  organs  of  the  same  animal  are  compared  with  one  another.  Those  anal- 
ogies which  exist  between  the  various  parts  that  compose  the  trunk  could  not,  with  pro- 
priety, be  included  in  a  work  on  descriptive  anatomy.  But  we  do  not  deem  it  proper  to 
apply  the  same  rule  to  the  parallel  between  the  upper  and  lower  extremities  ;  for  that  is 
founded  on  such  numerous  and  striking  points  of  analogy,  and  has  become  so  much  a 
subject  of  instruction,  that  we  should  consider  it  a  serious  omission  did  we  here  neglect 
giving  a  brief  notice  of  it. 

The  upper  and  the  lower  extremities  are  evidently  constructed  after  the  same  type, 
but  present  certain  modifications  corresponding  to  the  difference  of  their  functions.  I 
should  remark  in  this  place,  that  some  of  these  analogies  are  very  manifest  and  satis- 
factory, and  greatly  facilitate  the  remembrance  of  important  anatomical  details  ;  while 
others  are  far-fetched,  and  wholly  destitute  of  useful  application :  these  will  be  passed 
over  with  a  simple  notice.  We  shall  now  compare  in  succession  the  shoulder  and  the 
haunch,  the  humerus  and  the  femur,  the  forearm  and  the  leg,  the  hand  and  the  foot. 

Comparison  of  the  Shoulder  and  the  Pelvis. 
Before  the  time  of  Vicq-d'Azyr,  anatomists  were  in  the  habit  of  considermg  the  clavi- 
cle and  the  scapula  among  the  bones  of  the  upper  extremity,  but  regarded  the  os  innom- 
inatum  or  haunch  as  belonging  to  the  trunk ;  and  yet  the  most  simple  reflection  is  suf- 
ficient to  establish  the  analogy  between  the  shoulder  and  the  haunch.  In  order  the 
more  readily  to  appreciate  the  points  of  resemblance  and  difference  between  these  parts, 
it  is  advisable  to  follow  the  method  adopted  by  Vicq-d'Azyr,  of  studying  the  shoulder 
reversed ;  or,  what  is  the  same  thing,  to  compare  the  aspect  of  the  shoulder  which  cor- 
responds to  the  head,  with  that  of  the  pelvis  which  answers  to  the  coccyx ;  remember- 
ing, at  the  same  time,  that,  for  a  long  period  after  birth,  the  haimch  bone  is  formed  of 
three  distinct  pieces,  the  ilium,  the  ischium,  and  the  pubes. 

1.  The  shoulders  form  an  osseous  girdle,  intended  to  form  a  point  of  support  for  the 
upper  extremities,  in  the  same  manner  as  the  haunch  does  for  the  lower  extremities. 
The  girdle  formed  by  the  shoulders  is  interrupted  in  front  in  the  situation  of  the  sternum, 
and  behind,  opposite  the  vertebral  column ;  hence  there  are  two  shoulders,  while  the 
haunch  bones  constitute  one  united  whole.  The  shoulder,  therefore,  and,  consequently, 
the  arm  of  one  side,  are  completely  independent  of  those  of  the  other,  but  the  two  lower 
extremities  have  a  sohd  bond  of  union. 

2.  The  second  point  of  difference  relates  to  the  comparative  dimensions  of  the  pelvis 
and  the  shoulder.  The  great  size  of  the  pelvis,  the  thickness  of  its  edges,  the  depth  of 
its  notches,  and  the  prominence  of  its  eminences,  contrast  strongly  with  the  slender 
construction  of  the  shoulder,  and  the  thin  edges  of  the  scapula,  and  are  in  harmony  with 
the  uses  of  the  lower  extremities. 

3.  The  broad  portion  of  the  scapula  is  analogous  to  the  iliac  portion  of  the  os  innom- 
inatum  ;  the  internal  iliac  fossa  is  analogous  to  the  subscapular  fossa. 

4.  The  supra  and  infra-spinous  fossae  correspond  to  the  external  iliac  fossa ;  but  the 
iliimi  has  no  part  analogous  to  the  spine  of  the  scapula. 

5.  The  axillary  border  of  the  scapula  answers  to  the  anterior  edge  of  the  os  innomi- 
natum.    The  spinal  border  is  analogous  to  the  crest  of  the  ilium.     The  superior  border 

*  On  thi»  subject  the  reader  may  consult  a  very  curious  memoir,  by  Camper,  on  the  inconveniences  arising 
from  tight  shoes,  to  which  he  attributes,  1.  The  shortening  of  the  second  toe  ;  2.  The  partial  luxation  of  some 
of  the  tarsal  bones.  To  this  vie  may  add  the  luxation,  outward,  of  the  first  phalanx  of  the  great  toe  ;  and  the 
luxation,  inward,  of  the  first  phalanx  of  the  second,  and  sometimes  of  the  third  toe. 

o 


106  OSTEOLOGY. 

of  the  scapula  corresponds  to  the  posterior  border  of  the  os  innominatuin ;  and  the  cora^ 
coid  notch  on  this  border,  with  the  coracoid  hgament  which  converts  it  into  a  foramen, 
are  analogous  to  the  sciatic  notch,  and  the  sacro-sciatic  ligaments. 

6.  The  glenoid  cavity  is  evidently  analogous  to  the  acetabulum ;  according  to  Vicq- 
d'Azyr,  the  coracoid  and  the  acromion  processes  are  represented  by  the  tuberosity  of 
the  ischium  and  the  pubes,  with  this  remarkable  difference  only,  that  the  two  processes 
of  the  shoulder  are  separated  from  each  other  by  the  large  acromio-coracoid  notch,  while 
in  the  pelvis  the  iscliium  and  the  pubes  are  united,  and,  instead  of  including  a  notch, 
form  the  circumference  of  a  foramen,  the  obturator.  This  analogy  is  not  universally 
admitted ;  for  the  ischium,  being  intended  to  sustain  the  weight  of  the  body  when  sit- 
ting, bears  no  resemblance  in  this  respect  to  the  shoulder.  One  of  the  most  striking 
analogies  between  the  shoulder  and  the  pelvis  is  that  of  the  clavicle  and  the  horizontiS 
portion  of  the  pubes  ;  with  this  difference,  that  the  clavicle  is  articulated  with  the  scap- 
ula, while  the  pubes  is  united  by  bone  to  the  ilium.  Without  forcing  an  analogy,  we 
may  trace  a  similitude  between  the  symphysis  pubis,  and  the  union  of  the  clavicles  by 
means  of  the  interclavicular  ligament. 

Comparison  of  the  Arm  Bone  and  the  Thigh. 

In  order  to  make  the  parallel  exact,  we  must  remember  the  relative  situation  of  the&o 
two  bones,  and  compare  the  right  femur  with  the  left  humerus  ;  and  the  side  of  flexion, 
that  is,  the  posterior  aspect  of  the  first,  with  the  side  of  flexion,  or  the  anterior  aspect  of 
the  second.  This  being  determined,  we  must  place  the  linea  aspera  of  the  femur  in  front, 
and  the  himierus  in  its  natural  position.  The  humerus  is  much  smaller  than  the  femur, 
being  about  a  third  shorter,  and  only  half  the  weight  and  bulk.  The  humerus  is  placed 
vertically,  and  almost  parallel  to  the  axis  of  the  trunk ;  in  this  it  contrasts  with  the 
marked  obliquity  of  the  thigh  bones,  which  touch  each  other  at  their  lower  ends.  The 
humeri  are  separated  from  each  other  by  a  greater  distance  than  the  femora  ;  this  differ- 
ence depends  on  the  conformation  of  the  human  thorax,  which  is  flattened  in  front  and 
behind,  while  in  quadrupeds  it  is  flattened  on  the  sides,  and  permits  the  approximation 
of  the  humeri,  which  serve  as  pillars  of  support  to  the  fore  part  of  the  trunk. 

The  humerus  is  not  curved  like  the  femur,  but,  on  the  other  hand,  it  is  much  more 
twisted,  and  presents  an  oblique  groove,  which  does  not  exist  in  the  femur.  We  shall 
compare  in  succession  the  shafts  and  the  extremities  of  these  bones. 

1.  Comparison  of  the  Shafts. — -The  posterior  surface  of  the  humerus  exactly  corresponds 
to  the  anterior  surface  of  the  femur,  being,  like  it,  smooth  and  rounded.  The  external 
surface  resembles  the  external  plane  of  the  femur,  with  some  differences  ;  the  impres- 
sion for  the  gluteus  maximus  is  evidently  analogous  to  the  deltoid  impression.  The  in- 
ternal surface  is  in  contact  with  the  brachial  artery,  as  is  the  internal  surface  of  the 
femur  with  the  femoral  artery.  The  anterior  edge  is  a  sort  of  linea  aspera,  analogous 
to  that  of  the  femur,  and,  like  it,  terminating  by  a  bifurcation  at  its  upper  part. 

2.  Comparison  of  the  Loicer  Ends  of  the  Bones. — Although  the  differences  between 
these  parts  are  very  marked,  we  can  yet  detect,  in  the  one  bone,  traces  of  all  the  more 
important  points  of  structure  observed  in  the  other.  Thus,  the  internal  and  external 
tuberosities  of  the  humerus  evidently  resemble  those  of  the  femur,  and  they  are  both 
intended  for  the  insertion  of  muscles  and  ligaments.  The  trochlea  of  the  humerus  re- 
sembles that  of  the  femur,  with  this  difference,  that,  in  the  femur,  the  two  borders  of 
the  pulley  diverge  from  each  other  behind,  while  in  the  humerus  they  are  parallel  through- 
out. In  front  and  behind  the  femoral  trochlea,  we  find  depressions,  wliich  are  manifestly 
analogous  to  the  coronoid  and  olecranal  fossae  of  the  humeral  trochlea.  Lastly,  without 
admitting  any  fundamental  difference,  we  may  explain  the  existence  of  the  small  head 
of  the  humerus,  for  which  there  is  no  representative  in  the  femur,  by  a  reference  to  the 
fact,  that  both  bones  of  the  forearm  unite  with  the  humerus,  while  only  one  bone  of  the 
leg  articulates  with  the  femur. 

Comparison  of  the  Upper  Ends. — As  in  the  femur,  we  find  in  the  humerus  a  segment 
of  a  spheroid,  or  a  head,  supported  by  a  neck,  of  which,  however,  there  is  only  a  trace  ; 
and  two  tuberosities,  which  are  analogous  to  the  trochanters,  and,  like  them,  give  at- 
tachment to  the  rotator  muscles  of  the  Umb.  In  the  humerus,  however,  the  two  pro- 
cesses are  much  more  closely  approximated,  being  only  separated  by  the  bicipital  groove. 
Lastly,  the  great  tuberosity  of  the  humerus  causes  the  prominence  of  the  shoulder,  in 
the  same  manner  as  the  great  trochanter  causes  the  prominence  of  the  hip. 

Comparison  of  the  Leg  and  Forearm. 

The  forearm  is  that  portion  of  the  upper  extremity  which  is  represented  by  the  leg  in 
the  lower.  Each  is  composed  of  two  bones  ;  but  while  the  leg  is  essentially  constitu- 
ted by  the  tibia,  which  alone  enters  into  the  formation  of  the  knee-joint,  and  the  greater 
part  of  the  ankle-joint,  both  the  radius  and  the  ulna  contribute,  almost  in  an  equal  degree, 
to  that  of  the  forearm ;  and  although  the  ulna  forms  the  greater  part  of  the  elbow-joint, 
the  radius,  by  a  sort  of  compensation,  is  the  chief  bone  of  the  wrist-joint. 

Although  the  general  analogy  between  the  forearm  and  leg  is  sufficiently  striking,  it  js 


COMPARISON    OP   THE    EXTREMITIES.  107 

not  so  easy  to  trace  the  corresponding  parts  in  detail.    Anatomists  are  much  at  variance 
on  this  subject,  particularly  as  to  which  bone  of  the  forearm  corresponds  to  the  tibia. 

Vicq-d'Azyr,  from  a  consideration  of  the  elbow  and  the  knee  joints,  came  to  the  con- 
clusion that  the  ulna  is  analogous  to  the  tibia,  and  the  radius  to  the  fibula.  M.  de  Blain- 
Tille,  on  the  contrary,  reflecting  on  the  relations  between  the  leg  and  foot,  and  the  fore 
arm  and  hand,  and  considering  that  the  tibia  is  placed  on  the  same  line  with  the  great  toe, 
and  the  radius  with  the  thumb,  and  also  that  in  the  forearm  the  radius  constitutes  the 
chief  part  of  the  wrist-joint,  and  that  in  the  leg  the  tibia  is  most  concerned  in  the  ankle- 
joint,  is  of  opinion  that  the  tibia  and  the  radius  are  analogous  parts. 

We  shall  adopt  what  is  true  in  either  opinion,  and  reject  what  appears  to  us  too  un 
conditionally  stated  or  incorrect ;  and,  therefore,  considering,  1.  That  neither  of  the  bones 
of  the  leg  resembles,  by  itself,  one  of  the  bones  of  the  foreann ;  2.  That  each  bone  of  the 
leg  has  some  characters,  both  of  the  ulna  and  of  the  radius  ;  3.  That  the  natural  position 
of  the  forearm  being  that  of  pronation,  and  that  the  leg  being  in  a  state  of  constant  pro- 
nation, it  is  incorrect  to  compare  the  forearm  when  supinated  with  the  leg  when  in  the 
opposite  position ;  4.  That  comparative  anatomy  has  shown,  in  ruminating  animals,  the 
upper  extremity  of  the  ulna  to  be  blended  with  the  radius,  and  a  slender  process  on  the 
external  aspect  of  the  forearm  resembUng  the  fibula,  we  are  inclined  to  believe  that  the 
upper  end  of  the  tibia  is  represented  by  the  upper  lialf  of  the  ulna,  and  the  lower  half  of 
the  tibia  by  the  lower  half  of  the  radius  ;  while  the  fibula  is  represented  by  the  upper  part 
of  the  radius  and  the  lower  part  of  the  ulna.  If  we  enter  into  details,  we  shaU  see  how 
plausible  this  comparison  is  in  reality. 

Comparison  of  the  Upper  Half  of  the  Ulna  and  the  Upper  Half  of  the  Tibia. 

The  horizontal  portion  of  the  great  sigmoid  cavity  of  the  ulna  is  represented  by  the 
upper  end  of  the  tibia,  and  the  crest  which  separates  the  two  surfaces  of  the  cavity  is 
analogous  to  the  spine  of  the  tibia.  The  patella  and  the  olecranon  are  constructed  after 
the  same  type ;  the  mobility  of  the  first,  and  the  fixture  of  the  last,  are  not  essential  dif- 
ferences. The  body  of  the  ulna  is  prismatic  and  triangular,  like  that  of  the  tibia ;  its  in- 
ternal surface  is  superficial  and  almost  subcutaneous,  like  the  anterior  surface  of  the 
tibia ;  its  posterior  edge  (crest  of  the  ulna)  is  prominent,  and  represents  the  crest  of  the 
tibia ;  it  is  equally  superficial,  and  serves  as  a  guide  in  the  diagnosis  and  coaptation  of 
fractures.  As  in  the  tibia,  the  crest  of  the  ulna  is  continuous  with  a  triangular  tuberosity, 
which  may  be  called  the  posterior  tuberosity  of  the  ulna,  and  is  analogous  to  the  anterior 
tuberosity  of  the  tibia. 

Comparison  of  the  Lower  Part  of  the  Radius  and  the  Lower  Part  of  the  Tibia. 

The  quadrangular  lower  end  of  the  radius  corresponds  to  the  equally  quadrangulai 
lower  extremity  of  the  tibia.  The  inferior  articular  surface  of  both  is  divided  into  two 
parts,  by  an  antero-posterior  ridge.  The  ulnar  side  of  the  lower  end  of  the  radius  is 
hollowed  into  an  articular  cavity,  in  the  same  way  as  the  fibular  side  of  the  lower  end 
of  the  tibia.  The  styloid  process  of  the  radius  answers  to  the  internal  malleolus  of  the 
tibia.    Both  extremities  exhibit  furrows  for  the  passage  of  tendons. 

Comparison  of  the  Hand  and  Foot. 
The  back  of  the  foot  corresponds  with  the  back  of  the  hand,  the  sole  with  the  palm,  the 
tibial  edge  of  the  one  with  the  radial  edge  of  the  other ;  the  fibular  and  the  ulnar  borders 
are  analogous  ;  the  tarsal  extremity  of  the  foot  corresponds  with  the  carpal  extremity  of 
the  hand,  and  each  has  a  digital  extremity.  But  amid  these  features  of  resemblance, 
which  are  sufficient  to  establish  the  old  adage,  pes  altera  manus,  we  find  also  great  dif- 
ferences. Thus  the  foot  exceeds  the  hand  both  in  size  and  weight,  being  longer  and 
thicker,  though  it  is  narrower :  this  excess  of  volume  does  not  affect  the  toes,  which  are 
mcomparably  smaller  than  the  fingers  ;  nor  the  metatarsus,  but  is  confined  to  the  tarsus, 
of  which  the  carpus  seems  little  more  than  a  vestige.  A  second  characteristic  differ- 
ence is  the  absence  of  the  power  of  opposition  in  the  great  toe.  As  far  as  regards  func- 
tion, indeed,  it  may  be  truly  said,  that  the  want  of  this  power  constitutes  a  foot,  and  the 
Eossession  of  it  a  hand.  A  third  difference  results  from  the  mode  of  articulation  of  the 
jg  with  the  foot,  for  the  leg  does  not  articulate  with  the  posterior  extremity  of  the  tar- 
sus, but  Avith  its  upper  surface,  so  that  a  part  of  the  tarsus  projects  behind  the  joint,  and 
the  axis  of  the  foot  forms  a  right  angle  with  that  of  the  leg.  These  remarks  will  suffice 
to  show  the  general  differences  between  the  hand  and  the  foot. 

Comparison  of  the  Bones  of  the  Carpus  and  Tarsus. 
While  the  carpus  scarcely  forms  the  eighth  part  of  the  hand,  the  tarsus  constitutes 
half  the  foot.  Its  antero-posterior  diameter,  which  is  five  or  six  inches,  is  three  times 
greater  than  the  transverse  diameter,  precisely  contrary  to  what  is  the  case  in  the  hand. 
The  tarsus  resembles  a  vault,  concave  below,  both  in  the  antero-posterior  and  transverse 
directions,  and  receives  the  leg  upon  its  summit.  The  carpus  is  nothing  more  than  a 
groove  for  tendons.  It  is  manifest  that  the  carpus  is  only  the  rudiment  of  the  tarsus, 
which  is  not  surprising,  if  we  consider  that  the  former  is  truly  the  fundamental  part  of 


lOS  OSTEOLOGY. 

the  foot,  and  the  basis  of  support  to  the  whole  body.  We  shall  examine  in  detail  the 
analogies  and  the  differences  of  these  two  constituent  parts  of  the  foot  and  the  hand. 
They  differ  in  the  following  respects  :  1.  There  are  eight  bones  in  the  carpus  :  there  are 
only  seven  in  the  tarsus.  2.  Each  of  the  two  rows  of  the  carpus  is  composed  of  four 
bones  :  the  first  row  of  the  tarsus  consists  of  two  bones,  and  the  second  of  five  ;  3.  The 
bones  of  the  first  row  of  the  tarsus  are  placed  one  above  the  other,  not  arranged  side  by 
side  as  in  the  first  row  of  the  carpus.  4.  One  tarsal  bone  only  enters  into  the  formation 
of  the  ankle-joint,  while  three  of  the  carpal  bones  are  concerned  in  the  wrist-joint :  last- 
ly, the  second  row  of  the  tarsus  is  subdivided  into  two  secondary  rows  on  the  inside,  a 
posterior,  formed  by  the  scaphoid,  and  an  interior,  formed  by  the  three  cuneiform  bones. 
We  shall  now  compare  the  bones  of  these  two  regions,  and  for  the  want  of  their  re- 
semblance in  shape,  we  shall  have  recourse  to  that  of  their  mode  of  connexion — a  meth- 
od which  is,  perhaps,  more  constant  and  important  than  that  which  is  founded  upon  a 
character  so  variable  as  figure. 

Comparison  of  the  Metatarsal  Row  of  the  Tarsus  with  the  Metacarpal  Row  of  the  Carpus. 

The  metatarsal  and  the  metacarpal  rows  are  evidently  more  analogous  to  each  other 
than  the  first  rows  of  each  region,  and  have,  therefore,  been  chosen  for  the  purpose  of 
establishing  the  parallel. 

1.  The  cuboid  is  manifestly  analogous  to  the  os  unciforme  ;  their  relative  positions 
are  the  same  ;  their  forms  are,  in  a  great  measure,  similar ;  and  while  the  cuboid  is  at- 
tached to  the  last  two  metatarsal  bones,  the  os  unciforme  articulates  with  the  last  two 
metacarpal.  This  analogy  being  admitted,  we  shall  find  in  the  three  cuneiform  bones 
the  representatives  of  the  three  other  bones  of  the  second  row  of  the  carpus,  viz.,  the 
trapezium,  the  trapezoid,  and  the  os  magnum. 

2.  We  must  admit  here  that  the  analogies  now  become  much  less  evident.  Never- 
theless, the  third  cuneiform  bone,  which,  from  being  in  contact  with  the  cuboid,  should 
represent  the  os  magnum,  which  is  contiguous  to  the  os  unciforme,  does  so  far  agree, 
that  it  articulates  with  the  third  metatarsal  bone,  as  the  os  magnum  does  with  the  third 
metacarpal ;  and,  what  is  sufficiently  remarkable,  the  third  cuneiform  has  a  slight  con- 
nexion with  the  second  metatarsal,  as  the  os  magnum  has  with  the  second  metacarpal. 
Although,  therefore,  we  do  not  find  in  the  third  cuneiform  bone  anything  approaching 
to  the  size  of  the  os  magnum,  or  resembling  the  remarkable  head  of  that  bone,  we  should 
not,  on  that  account,  hastily  conclude  that  they  have  no  analogy.  We  shall  explain  af- 
terward how  this  fact  should  be  interpreted :  we  only  wish  it  to  be  admitted  in  this 
place,  that  the  base  or  metacarpal  portion  of  the  os  magnum  is  represented  by  the  third 
cuneiform  bone. 

3.  The  second  cuneiform  bone,  which  corresponds  to  the  trapezoid,  supports  the  sec- 
ond metatarsal,  as  the  trapezoid  supports  the  second  metacarpal. 

4.  The  first  cuneiform  bone,  which  supports  the  first  metatarsal,  corresponds  to  the 
trapezium,  which  supports  the  first  bone  of  the  metacarpus.  All  these  analogies,  it  must 
be  confessed,  are  very  imperfect,  and  founded  rather  upon  the  connexions  than  the  forms 
of  the  different  bones.  In  fact,  what  resemblance  is  there  between  the  three  large  cu- 
neiform bones  all  cut  into  facette-like  wedges,  and  all  so  like  each  other  in  shape,  and 
the  bones  of  the  carpus,  to  which  we  have  compared  them  1  Above  all,  what  compari- 
son can  be  established  between  the  third  cuneiform,  which  exactly  resembles  a  wedge, 
and  the  os  magnum,  which  has  a  rounded  head  1  There  is  nothing  in  the  metatarsal 
range  of  the  tarsus  which  represents  the  rounded  head  which  belongs  to  the  metacarpal 
row  of  the  carpus  ;  but  the  following  considerations,  which  did  not  escape  the  notice  of 
Vicq-d'Azyr,  will  serve  to  solve  the  difficulty. 

1.  It  is  an  observation  which  apphes  with  sufficient  generality  to  the  whole  skeleton, 
that  when  two  bones  move  upon  each  other,  one  being  provided  with  a  head,  and  the 
other  with  a  cavity,  the  head  moves  upon  the  cavity,  not  the  cavity  on  the  head.  Thus, 
the  femur  moves  upon  the  os  innominatum ;  the  humerus  upon  the  scapula.  2.  The  hand, 
in  the  performance  of  its  functions,  almost  always  moves  upon  the  forearm.  In  the  move- 
ments of  the  hand,  the  metacarpal  row  of  the  carpus  moves  upon  the  first  row,  and 
therefore  the  metacarpal  row  presents  the  head.  On  the  contrary,  in  the  movements  of 
the  bones  of  the  tarsus  during  progression,  the  bones  of  the  first  row  always  move  upon 
those  of  the  second  or  metatarsal  row ;  and  consequently,  instead  of  finding  a  rounded 
head  in  the  second  row,  we  meet  with  it  in  the  first. 

Proceeding  thus  by  the  method  of  exclusion,  it  now  only  remains  for  us  to  establish 
the  analogy  between  the  bones  of  the  first  row  of  the  carpus  on  the  one  hand,  and  the 
scaphoid,  the  os  calcis,  and  astragalus  on  the  other.  The  analogies  here  are  very  equiv 
ocal,  and  are  not  agreed  upon  among  anatomists. 

Comparison  of  the  First  Row  of  the  Tarsus  with  the  First  Rmo  of  the  Carpus. 

As  there  are  only  three  bones  in  the  posterior  row  of  Uie  tarsus  which  correspond  to 
the  antibrachial  or  superior  row  of  the  carpus,  it  might  be  supposed,  d  priori,  that  one  of 
these  would  correspond  to  two  of  the  bones  of  the  first  row  of  the  carpus.    A  verv  slight 


COMPARISON    OP    THE   EXTREMITIES.  109 

examination  of  the  tarsus  and  the  carpus  in  a  quadruped  will  show  at  once  that  the 
pisiform  bone  is  represented  by  that  part  of  the  os  calcis  which  projects  behind  the  as- 
tragalus. The  OS  calcis  is  the  only  bone  of  the  tarsus  which  is  developed  from  two 
points  ;  and  this  establishes  a  strong  presumption  in  favour  of  the  opinion  that  it  repre- 
sents two  bones.  If  we  admit  the  analogy  of  the  back  part  of  the  os  calcis  with  the  pi- 
siform bone,  the  anterior  portion  of  this  bone  would  represent  the  cuneiform  or  pyram- 
idal bone  of  the  carpus ;  and  as  this  last  articulates  with  the  os  unciforme,  so  the  an- 
terior portion  of  the  os  calcis  unites  with  its  representative,  the  cuboid.  The  os  calcis, 
then,  may  be  considered  as  representing  the  cuneiform  and  the  pisiform  bones  blended 
together,  and  much  augmented  in  size. 

It  remains,  then,  to  establish  the  analogy  between  the  scaphoid  and  semilunar  bones  of 
the  hand,  and  the  astragalus  and  scaphoid  of  the  foot. 

The  scaphoid  of  the  hand  resembles  the  scaphoid  of  the  foot,  both  in  form  and  con- 
nexions. The  similarity  of  shape  has  led  to  the  identity  of  name  ;  and,  with  regard  to 
connexions,  we  find  that  the  scaphoid  of  the  foot  is  attached  to  the  three  cuneiform 
bones,  and  that  of  the  hand  to  the  trapezium,  the  trapezoid,  and  the  os  magnum,  which 
represent  the  three  cuneiform  bones  ;  and,  lastly,  we  observe  that  the  scaphoid  bone  of 
the  foot  is  placed  on  the  same  side  as  the  great  toe,  and  that  the  scaphoid  bone  of  the 
hand  is  placed  on  the  same  side  as  the  thumb.  There  is,  however,  one  remarkable  dif- 
ference between  them,  viz.,  that  the  scaphoid  bone  of  the  hand  articulates  with  the  fore- 
arm, while  that  of  the  foot  has  no  connexion  with  the  leg. 

"We  have  now  only  to  discover  in  the  tarsus  the  representative  of  the  semilunar  bone. 
All  the  rest  of  the  bones  being  now  excluded,  we  can  only  conclude,  with  Vicq-d'Azyr, 
that  the  astragalus  is  its  counterpart,  with  the  mere  addition  of  a  rounded  head. 

Comparison  of  the  Metacarpus  and  the  Metatarsus. 

Five  small  long  bones,  arranged  parallel  to  eacli  other,  form  both  the  metacarpus  and 
the  metatarsus.  In  both  there  are  four  interosseous  spaces :  these  are  larger  in  the 
hand  than  in  the  foot,  because  there  is  a  greater  disproportion  between  tlie  bulk  of  the 
extremities  and  shafts  of  the  metacarpal  than  of  the  metatarsal  bones  :  the  metacarpus, 
from  being  shorter,  appears  broader  than  the  metatarsus.  The  most  distinguishing  char- 
acter of  the  metacarpus  is  the  fact,  that  the  metacarpal  bone  of  the  thumb  is  the  short- 
est of  the  whole,  and  is  situated  on  a  plane  anterior  to  the  others,  and  that  its  direction 
is  oblique,  aU  which  circumstances  bear  reference  to  the  movement  of  opposition,  which 
is  peculiar  to  the  hand.  The  characteristic  mark  of  the  inetatarsus  is  the  size  of  the 
first  metatarsal  bone,  which  greatly  exceeds  that  of  all  the  others.  The  great  size  of 
the  tarsus  is  continued  in  this  bone  and  the  great  toe,  on  account  of  the  important  part 
they  perform  in  the  mechanism  of  standing.  There  is  so  great  a  resemblance  between 
the  other  metacarpal  and  metatarsal  bones,  that  some  attention  is  necessary  in  order  to 
distinguish  between  them.  1.  The  metatarsal  bones  gradually  diminish  in  size  from 
their  tarsal  to  their  digited  extremities  ;  the  metacarpal  bones,  on  the  contrary,  are  most 
expanded  at  their  digital  ends.  The  metacarpal  are  shorter  and  thicker ;  the  metatar- 
sal longer  and  more  slender.  The  shaft  of  the  metacarpal  bones  is  pretty  regularly  pris- 
matic and  triangular  ;  that  of  the  metatarsal,  on  the  contrary,  is  compressed  or  flatten- 
ed on  the  sides.  2.  There  are  no  well-marked  differences  between  the  carpal  extremi- 
ties of  the  metacarpal  bones  and  the  tarsal  extremities  of  the  metatarsal ;  but  the  lat- 
ter are  larger  than  the  former,  which  agrees  with  the  greater  dimensions  of  the  tarsus. 
3.  The  tarsal  extremities  are  more  regularly  cuneiform  than  the  corresponding  ends  of 
the  metacarpal  bones. 

The  most  characteristic  differences,  however,  of  these  two  series  of  bones  are  found 
in  the  digital  extremities,  which  are  incomparably  larger  in  the  metacarpus  than  in  the 
metatarsus,  the  fingers  being  the  chief  part  of  the  hand,  while  the  tarsus  is  the  principal 
portion  of  the  foot.  We  should  also  remark,  that  the  convex  articular  surfaces  of  the 
digital  ends  of  the  metatarsal  bones  are  prolonged  farther  on  the  dorsal  aspect  than  the 
corresponding  surfaces  of  the  metacarpal  bones. 

Comparison  of  the  Phalanges  of  the  Fingers  and  Toes. 

The  fingers,  being  the  essential  organs  of  prehension  and  the  fundamental  part  of  the 
hand,  greatly  exceed  the  toes  both  in  length  and  thickness,  and  the  latter  may  be  looked 
upon  as  representing  in  rudhnent  the  former,  being  precisely  analogous  in  structure. 

The  phalanges  of  the  toes  may,  therefore,  be  regarded  as  phalanges  of  the  fingers  in 
a  state  of  atrophy ;  but  the  great  toe  forms  a  remarkable  exception  to  this  rule,  for  its 
phalanges  are  much  larger  in  proportion  to  the  other  toes  than  the  phalanges  of  the 
thumb  are  to  the  other  fingers.  This  magnitude  of  the  great  toe  corresponds  to  the  size 
of  its  metatarsal  bone,  and  accords  with  its  destination,  as  constituting  the  principal  sup- 
■^rt  for  the  weight  of  the  body  in  front.  The  first  phalanx  of  the  toes  exactly  resembles 
the  first  phalanx  of  the  fingers  in  all  things  but  volume.  The  middle  phalanx  of  the  toes 
can  scarcely  be  recognised,  from  its  diminutive  size  :  it  may  be  said  to  want  the  shaft  al- 
together, the  extremities  being  in  contact.     As  we  have  already^remarked,  it  might  at 


110  OSTEOLOGY. 

first  sight  be  confounded  with  a  pisiform,  or  a  sesamoid  bone,  or  still  more  readily  with 
a  piece  of  the  coccyx. 

Comparison  of  the  Upper  and  Lower  Extremities  with  regard  to  Development. 

The  development  of  the  lower  extremities  is  proportionally  less  rapid  than  that  of  the 
upper.  The  clavicle  and  the  scapula  are  ossified  before  the  os  innominatum.  The  os- 
sification of  the  skeleton  commences  in  the  clavicle  ;  in  this  bone,  the  osseous  nodule  is 
visible  from  the  twenty-fifth  to  the  thirtieth  day ;  it  appears  in  the  scapula  about  the  for- 
tieth day.  The  osseous  point  of  the  ilium  is  visible  about  the  forty-fifth  day,  that  of  the 
ischium  in  the  third  month,  and  that  of  the  pubes  in  the  fifth  month.  The  scapula  is 
completely  ossified  at  the  age  of  twenty  years  ;  the  marginal  process  of  the  crest  of  the 
ilium  is  scarcely  united  until  the  twenty-fifth  year.  The  bony  centres  of  the  shafts  of 
the  femur  and  humerus  are  almost  simultaneous  in  their  appearance.  The  germ  of  the 
lower  end  of  the  femur  always  exists  at  birth ;  that  of  the  lower  end  of  the  humerus  does 
not  appear  until  the  end  of  the  first  year ;  but  this  latter  unites  with  the  bone  at  eighteen 
years,  while  the  former  is  still  separate  at  twenty  years.  The  tibia  is  ossified  a  little  be- 
fore the  bones  of  the  forearm,  the  fibula  a  little  after  them.  The  ossification  of  the  leg 
and  the  forearm  is  completed  almost  about  the  same  time.  The  ossification  of  the  bones 
of  the  tarsus  precedes  that  of  the  carpus  by  a  considerable  period.  Thus,  at  from  foui 
and  a  half  to  five  months  of  foetal  life,  a  bony  point  is  visible  in  the  os  calcis,  and  some 
days  after  in  the  astragalus  ;  the  os  magnum  and  os  cuneiforme  (which,  however,  ar« 
not  the  representatives  of  the  preceding)  do  not  show  ossific  points  until  a  year  after 
birth.  The  pisiform  bone  is  not  ossified  until  the  twelfth  year ;  while  the  latest  of  the 
tarsal  bones,  the  scaphoid,  is  converted  into  bone  at  the  fifth  year.  Nevertheless,  the 
epiphysary  point  of  the  os  calcis  (which  we  have  shown  to  be  analogous  to  the  pisiform 
bone)  does  not  become  visible  until  the  tenth  year ;  this  fact  strengthens  the  analogy 
between  the  pisiform  bone  and  the  epiphysary  lamina  of  the  os  calcis. 

The  metatarsal  bones  are  developed  in  exactly  the  same  manner  as  the  metacarpal, 
only  at  a  somewhat  later  period.  The  union  of  the  epiphyses  takes  place  a  little  earlier 
in  the  metatarsus  than  in  the  metacarpus.  The  toes  are  ossified  at  a  later  period  than 
the  fingers ;  especicdly  the  ungual  and  the  second  phalanges,  which  are  much  later  than 
those  of  the  fingers. 

It  is,  no  doubt,  impossible  to  state  the  precise  reason  for  these  differences ;  but  it  is 
sufficient  to  find  a  positive  relation  between  the  rate  of  development  of  these  parts,  and 
the  offices  they  are  intended  to  fulfil. 

The  Os  Hyoides,  or  the  Hyoid  Apparatus*  (fig.  57). 

The  OS  hyoides  has  a  parabolic  form,  resembling  the  upsilon  of  the  Greeks,  whence  its 
name.     It  is  the  only  bone  which  is  detached  from  the  rest  or 
Fig.  57.  ^   the  skeleton  ;  it  is  connected  only  by  ligaments  and  muscles,  and 

is  situated  between  the  base  of  the  tongue  and  the  larynx.  It  is 
larger  in  the  male  than  in  the  female.  It  is  placed  almost  hori- 
zontally, the  concavity  of  its  curve  looking  backward,  and  the 
convexity  forward. 

This  bone  is  divided  into  five  parts ;  viz.,  a  body  or  middle 
part  (a),  ani  four  cornua,  two  large  (J)  and  two  small  (c).  This 
multiplicity  of  parts,  which  is  much  greater  in  some  animals,  es- 
pecially fishes,  justifies  the  name  of  "  hyoid  apparatus,"  which 
we  have  adopted.! 

The  body  of  the  os  hyoides  (a)  is  quadrilateral,  elongated,  and  curved,  with  the  cavity 
behind.  Its  anterior  surface  looks  upward,  and  presents  a  crucial  projection,  the  vestige 
of  a  process  which  in  many  animals  is  prolonged  into  the  substance  of  the  tongue.  This 
projection  gives  attachment  to  several  muscles,  the  insertions  of  which  are  marked  by 
transverse  lines,  interrupted  by  tubercles.  The  posterior  surface,  more  or  less  excavated 
in  different  individucds,  is  sometimes  connected  with  a  yellow  ceUular  tissue,  which  sep- 
arates it  from  the  epiglottis,  and  is  sometimes  covered  by  a  synovial  membrane.  Its  ex- 
cavation, which  is  never  very  great  in  man,  is  the  vestige  of  the  enormous  cavity  which 
exists  in  the  hyoid  of  the  Howler  monkey.  The  lower  edge  gives  attachment  to  the  thy- 
ro-hyoid  muscle  only.  The  upper  edge  gives  insertion  to  a  yeUow  membrane,  a  sort  ol 
ligament  which  stretches  into  the  tongue  ;  and  also  to  the  yeUow  thyro-hyoid  ligament, 
which  has  been  incorrectly  stated  to  be  inserted  into  the  lower  edge  of  the  bone.  The 
extremities  of  the  body  of  the  os  hyoides  are  covered  by  cartilage  for  articulation  with 
the  great  cornua. 

The  great  cornua  or  rami  {b)  are  much  longer  than  the  body,  and  flattened  above  and 
below,  while  the  body  is  compressed  from  before  backward.  They  are  expanded  at  the 
place  where  they  articulate  with  the  body,  pass  backward,  and,  after  being  contracted 

*  I  have  introduced  the  description  of  the  os  hyoides  into  this  place,  because,  although  chiefly  belonging  to 
the  tongue,  it  gives  attachment  to  several  muscles,  and,  therefore,  should  be  previously  knovfn  to  the  student 
t  Vide  M   QeofFroy  Saint-Hilaire,  on  the  anterior  bones  of  the  chest. — {Philos.  Anat.,  vol.  i.,  p.  139.) 


THE   ARTICULAR  CARTILAGES.  HI 

and  flattened,  terminate  in  a  rounded  tubercle,  which  is  sometimes  surmounted  by  an 
epiphysis.  ♦ 

The  little  comua  (c)  are  called  also  styloid  cornua,  because  they  are  connected  with  the 
styloid  process  by  means  of  a  ligament.  They  are  two  pisiform  nodules  at  the  point  of 
junction  of  the  great  comua  with  the  body  of  the  hyoid  {ossa  pisiformia  lingualia  of 
Soemmering).  They  surmount  the  upper  edge  of  the  bone,  and  are  directed  upward  and 
outward ;  their  length  is  very  variable.  In  the  lower  animals,  the  prolongations  which 
correspond  to  these  httle  cornua  are  much  longer  than  the  great  cornua  in  man.  They 
articulate  by  their  lower  end  with  the  body  and  the  great  cornua.  Their  upper  part  gives 
attachment  to  a  ligament,  which  unites  it  with  the  styloid  process.  This  ligament 
which  is  sometimes  ossified  in  man,  is  always  a  bony  connexion  in  the  lower  animals.* 

Internal  Structure. — The  hyoid  bone  is  composed  chiefly  of  compact  tissue  ;  but  there 
is  a  small  quantity  of  spongy  tissue  in  the  thick  parts  of  the  body  and  the  great  cornua. 

Development. — The  os  hyoides  is  developed  from  five  points  ;  one  for  the  body,  two  for 
the  great  comua,  and  two  for  the  little  cornua..  Some  anatomists  admit  two  points  for 
the  body,  and  make  the  whole  number  six. 

The  ossification  of  the  great  cornua  precedes  that  of  the  body,  which  becomes  bony 
soon  afl;er  birth  ;  the  little  cornua  are  not  ossified  until  some  months  afl;er.  All  the  pie- 
ces are  at  first  separated  by  considerable  portions  of  cartilage,  afterward  by  a  very  thin 
layer,  which  sometimes  remains  during  life,  and  gives  the  different  parts  of  the  bone  a 
great  degree  of  mobility. 


THE  ARTICULATIONS,  OR  ARTHROLOGY. 

General  Observations. — Articular  Cartilages. — Ligaments. — Synovial  Membranes. — Classi- 
fication of  the  Joints. — Diarthroses. — Synarthroses. — Amphiarthroses,  or  Symphyses. 

The  bones  are  united  together  by  the  joiTits  or  articulations.  The  study  of  these  parts 
is  the  object  of  syndesmology,  or,  more  properly,  of  arthrology  {apdpov,  a  joint).  In  exam- 
ining each  joint,  it  is  necessary  to  consider,  1.  The  contiguous  surfaces  of  the  bones,  or 
the  articular  surfaces ;  2.  The  uniting  medium,  or  the  ligaments ;  3.  The  means  or  condi- 
tions which  facilitate  the  motion  of  the  parts,  the  syiwvial  membranes  ;  and,  4.  The  move- 
ments of  which  the  joint  is  capable,  t 

It  is  impossible  to  insist  too  much  upon  the  importance  of  a  careful  study  of  the  artic- 
ulations. There  is  no  part  of  anatomy  a  thorough  knowledge  of  which  is  more  indis- 
pensable both  to  the  physiologist  and  the  surgeon  ;  without  it  the  former  cannot  form  a 
correct  idea  of  the  animal  mechanism,  nor  can  the  latter  appreciate  the  nature  of  those 
numerous  injuries  and  diseases  of  which  the  articulations  are  the  seat. 

Before  describing  the  forms  and  the  motions  of  the  different  joints,  it  is  necessary  to 
give  a  general  idea  of  the  articular  cartilages,  the  synovial  membranes,  the  hgaments, 
&c. ;  in  short,  of  all  the  means  which  contribute  to  secure  the  solidity  and  mobility  of 
the  articulations. 

The  Articular  Cartilages. 

It  has  been  observed,t  that  when  two  osseous  surfaces  in  immediate  contact  rub  upon 
each  other,  they  are  gradually  absorbed  in  such  a  manner  as  to  render  the  movements 
between  them  diflicult  and  painful.  In  order  to  avoid  these  injurious  effects  in  the  joints, 
the  contiguous  surfaces  of  the  bones  are  covered  by  a  layer  of  cartilage  (the  incrusting 
or  articular  cartilage),  a  substance  which  unites  in  itself  the  qualities  of  solidity,  pliability, 
and  elasticity  in  a  high  degree,  yielding  when  compressed,  and  returning  to  its  former 
state  when  the  pressure  is  removed.  These  articular  cartilages  exist  in  all  the  mova- 
ble joints.  The  extent  of  surface  which  they  cover  is  generally  proportioned  to  the  ex- 
tent of  motion  in  the  joints.  Their  thickness  is  generally  greatest  when  the  bones 
which  they  cover  are  most  movable,'  and  most  subjected  to  pressure.  An  articular  car- 
tilage is  not  of  uniform  thickness  throughout.  Thus,  on  convex  surfaces,  the  cartilagi- 
nous layer  is  thicker  in  the  centre  than  at  the  circumference  ;  and,  on  the  other  hand,  the 
cartilages  of  articular  cavities  are  thickest  at  the  circumference.  The  most  perfect  co- 
aptation results  from  this  arrangement.  It  should  also  be  remarked,  that  the  most  vio- 
lent shocks  are  applied  to  the  centre  of  the  heads  of  the  bones,  and  to  the  circumference 
of  the  cavities. 

The  articular  cartilages  present,  1.  A  free  surface,  perfectly  smooth  and  polished,  which 
is  in  the  interior  of  the  articulation ;  2.  An  adherent  surface,  which  is  so  closely  attached 

*  In  the  lower  animals,  the  styloid  process  is  detached  from  the  cranium,  and  forms  one  of  the  hyoid  chain 
of  bones,  which  is  composed,  1.  Of  the  five  pieces  of  the  os  hyoides  ;  2.  Of  the  bones  which  supply  the  place 
of  the  styloid  ligaments  ;  3.  Of  the  styloid  processes,  or,  rather,  bones  :  nine  pieces  in  all. 

t  Three  of  these,  viz.,  the  configuration  of  the  articular  surfaces,  the  ligaments,  and  the  niovements  of  the 
joint,  are  essentially  related  to  each  other;  so  that  we  may  deduce,  <i  priori,  the  means  of  union,  and  the 
movements  of  any  joint,  from  the  shape  of  the  articular  surfaces,  and  vice  verscL. 

%  Absorption  of  the  cartilages  is  a  frequent  disease  of  the  joints,  and  obliges  the  individuals  affected  by  h 
to  maintain  constant  rest 


112  ARTHROLOOy. 

to  the  tissue  of  the  bone,  that  it  is  impossible  to  separate  it  excepting  in  cases  of  disease. 
In  some  cases  of  white  swelling,  I  have  been  able  to  remove  the  articular  cartilages  with 
great  facility,  and  in  these  it  appeared  that  the  adherent  surface  of  the  cartilage  was 
very  irregular,  and  that  the  fibres  of  the  bone  were  implanted  in  it  by  innumerable  small 
prolongations. 

Tliere  is  another  kind  of  cartilage  existing  in  certain  joints,  in  the  form  of  thin  plates, 
having  both  surfaces  free,  and  being  interposed  between  two  articulating  bones.  These 
are  generally  found  in  such  joints  as  are  exposed  to  the  most  violent  shocks,  and  sub- 
jected to  the  most  frequent  movements  ;  they  are  known  by  the  name  of  inter-articular 
cartilages.  Their  use  is  to  adjust  the  contact  of  the  surfaces  on  the  bones,  to  moderate 
the  intensity  of  the  shocks  to  which  they  may  be  submitted,  to  increase  in  some  cases 
the  depth  of  the  articular  cavities,  and  to  impart  solidity  to  the  joints.  They  are  almost 
always  bi-concave,  from  which  circumstance  the  name  of  meniscus  is  sometimes  applied 
to  them  (from  iirjvrj,  lund) ;  they  are  thick  at  the  circimiference,  and  very  thin  in  the  cen- 
tre, which  is  sometimes  perforated. 

These  two  kinds  of  cartilage  are  found  only  in  those  joints  the  surfaces  of  which  are 
simply  in  contact. 

The  articulations  of  continuous  surfaces  are  provided  with  cartilages  very  different 
from  the  above,  and  which  should  be  looked  upon  as  non-ossified  portions  of  the  original 
cartilage  of  ossification.  The  progress  of  ossification  always  encroaches  upon  them, 
while  the  regular  articular  cartilages  are  never  affected  in  this  way.  It  will  be  seer 
afterward  that  the  articular  cartilages  are  inorganic,  like  the  enamel  of  the  teeth,  anc 
the  horny  tissues,  which  are  worn  away  by  attrition,  and  are  not  susceptible  of  any  le 
sions,  excepting  such  as  arise  from  mechanical  injury  or  chemical  action.* 

The  Articular  Ligaments.^ 

The  ligaments  constitute  a  very  important  division  of  the  fibrous  tissue,  which  is  met 
with  in  all  parts  where  great  resistance  and  great  flexibility  are  required,  and  in  no  part 
of  the  body  are  these  requisites  more  necessary  than  in  the  joints.  They  consist  of 
bundles  of  flexible  and  inextensible  fibres  of  a  pearly- white  lustre,  sometimes  parallel 
and  sometimes  interlaced.  Sometimes  tliey  are  placed  between  the  osseous  surfaces^ 
and  are  then  named  interosseous ;  sometimes,  on  the  contrary,  they  occupy  the  circum- 
ference of  the  surfaces,  and  are  then  called  peripheral  or  capsular.  The  peripheral  liga- 
ments present  two  surfaces :  a  deep  surface,  lined  by  the  synovial  membrane,  which  is 
intimately  united  to  it,  and  which  is  so  delicate  that  were  it  not  from  its  development  in 
disease,  its  existence  here  might  be  doubted ;  and  a  superficial,  which  is  in  contact  with 
the  muscles,  tendons,  nerves,  vessels,  and  cellular  tissue,  in  a  word,  to  all  the  structures 
which  surround  the  articulations ;  and  also  tico  extremities,  which  are  attached  to  the 
bones,  at  a  greater  or  less  distance  from  the  cartilage.  The  adhesion  of  these  parts  is 
so  intimate,  that  it  is  easier  to  break  either  the  ligament  or  the  bone  than  to  separate 
them  at  the  precise  place  of  their  union. 

The  ligaments  may  be  classed  under  two  very  distinct  heads  :  1.  The  fasciculated,  or 
those  which  exist  in  bundles ;  and,  2.  The  membranous  or  capsular.  The  ligaments, 
properly  so  called,  belong  to  the  first  class  ;  the  fibrous  capsules  belong  to  the  second. 
We  may  admit  a  third  form,  which  consists  of  scattered  fibres,  too  far  separated  to 
form  fasciculated  ligaments,  and  too  few  in  number  to  constitute  articular  capsules.  We 
should  include,  also,  in  the  class  of  articular  ligaments,  two  very  remarkable  modifica- 
tions of  the  fibrous  tissue:  1.  The  articular  borders;  these  are  circlets  of  fibres  which 
sunnountthe  margins  of  articular  cavities,  belonging  to  that  class  of  joints  denominated 
enarthroses  ;  they  augment  the  depth  of  the  cavities,  and  act  as  a  kind  of  pad  to  break 
the  force  of  impulsion  of  the  articular  head  against  the  brim  of  the  cavity,  and  prevent 
this  edge  from  breaking.  2.  The  yellow  or  elastic  ligaments,  which  are  characterized  by 
their  yellow  colour,  extensibility,  and  elasticity ;  hence  the  name  of  yellow  elastic  tissue 
has  been  given  to  them,  on  account  of  their  colour  and  chief  property. 

The  Synovial  Membranes^  or  Capsules. 
In  every  part  of  the  body  where  fibres  move,  they  are  surrounded  by  cellular  tissue, 
which  secretes  a  lubricating  fluid  to  facilitate  their  motions  ;  and,  where  surfaces  move 
upon  each  other,  they  are  covered  by  a  membrane  which  exudes  a  fluid,  varying  in  its 
nature  according  as  the  motions  are  confined  to  simple  gliding,  or  are  accompanied  by  a 
certain  amount  of  friction.  In  the  first  case,  the  membranes  secrete  a  watery  or  serous 
fluid,  and  are,  consequently,  denominated  serous  membranes ;  in  the  second,  the  liquid  is 
of  an  unctuous  nature,  resembling  white  of  egg ;  it  is  called  synovia  (avv,  with,  and  u6v, 
an  egg),  and  the  membrane  synovial  membrane.     All  the  movable  articulations  are  pra 

*  [Though  the  articular  cartilages  may  be  non-vascular,  it  is  scarcely  correct  to  say  that  they  are  unor- 
ganized.] 

t  The  word  ligament,  ovvlea/ios  of  the  Greeks,  copula  or  vinculum  of  the  Latins,  is  applied,  in  anatomy,  to 
any  structure  which  serves  to  unite  different  parts  to  each  other.  In  this  sense  we  speak  of  the  broad  and  the 
round  ligaments  of  the  uterus,  the  ligaments  of  the  bladder  and  of  the  liver.  Taken  in  its  most  limited  aeamtt 
this  name  applies  exclusively  to  the  articular  ligaments. 


CLASSIFICATION    OF   THE    JOINTS.  113 

Tided  with  a  synovial  membrane  or  capsule,  by  means  of  which  the  parts  are  constantly 
lubricated  with  a  viscid,  unctuous  fluid,  that  favours  the  exact  adaptation  of  the  articular 
surfaces,  obviates  the  effects  of  friction,  and  maintains  them  in  contact.  This  is  the 
cause  of  the  noise  or  cracking  which  results  from  the  sudden  separation  of  the  articulai 
surfaces. 

The  synovial  capsules,  which  have  been  well  described  by  Monro,  are  thin,  transparent 
membranes,  forming  shut  sacs,  which  cover  the  heads  of  the  bones  without  admitting 
them  into  the  interior  of  the  cavity.  In  fact,  it  is  their  external  surface  which  adheres 
more  or  less  intimately  to  the  ligaments  and  other  parts  which  surround  the  joint,  while 
their  internal  surfaces  are  in  contact  with  each  other,  and  are  constantly  lubricated  by 
the  synovia.  It  is  a  question  among  anatomists  whether  the  synovial  membrane  covers 
also  the  articular  cartilages.  It  can  only  be  traced  by  the  knife  as  far  as  the  circumfer- 
ence of  these  cartilages,  and  if  it  exists  on  them,  which  analogy  would  lead  us  to  be- 
lieve, it  is  so  completely  modified  as  not  to  be  recognisable.  Without  admitting  or  de- 
nying the  fact,  for  the  sake  of  facility  in  description,  we  shall  assume  the  continuity  of 
this  membrane  over  the  cartilages.  In  many  joints  the  synovial  membrane  is  raised 
from  the  surface  of  the  parts  by  a  subjacent  cushion  of  fat,  which  projects  into  the  joint, 
and  which  Clopton  Havers  imagined  to  be  a  gland  for  secreting  the  s)Tiovia.  I  believe 
that  this,  which  may  be  called  synovial  fatty  tissue,  is  only  intended  to  fill  up  the  spaces 
which  would  otherwise  be  formed  in  many  articulations  during  the  performance  of  cer- 
tain movements.  The  synovial  fringes,  described  by  the  same  author  as  the  excretory 
ducts  of  these  glands,  are  nothing  more  than  folds  of  the  membrane. 

Classification  of  the  Joints. 

The  multiphcity  of  the  articulations,  and  the  analogies  and  differences  which  they 
present,  have  induced  anatomists  to  arrange  them  in  a  determinate  number  of  groups, 
having  well-marked  characteristics.  The  shape  of  the  articulating  surfaces  in  each 
joint,  the  arrangement  of  the  uniting  media,  and  the  variety  and  extent  of  motions,  being 
necessarily  correlative,  either  of  these  three  circumstances  may  be  taken  as  the  basis  of 
classification.  Most  of  the  older  anatomists,  attending  specially  to  the  means  of  union, 
divided  the  articulations  into  four  classes  :  1 .  Synchondroses  {avv,  with,  and  x6v6po(,  a  car- 
tilage), when  the  bones  are  united  by  means  of  cartilage  ;  2.  Syneuroses  {avv,  with,  and 
vtvpov,  a  nerve,  the  synonyme  of  ligament  among  the  ancients),  when  the  connexion  is 
established  by  ligaments ;  3.  Syssarcoses  {avv,  with,  and  aup^,  flesh  or  muscle),  those 
joints  in  which  muscles  form  the  uniting  medium ;  4.  Meningoscs  {fi^viy^,  a  membrane), 
when  membranes  serve  as  ligaments,  as  in  the  bones  of  the  cranium  in  infants.  This 
classification  can  only  be  regarded  as  a  rough  sketch. 

Bichat,  fixing  his  attention  entirely  upon  the  movements,  has  divided  the  movable 
joints  according  to  the  variety  of  motions  of  which  they  are  capable.  There  are  four 
kinds  of  motion  :  1 .  Gliding ;  2.  The  movement  of  opposition,  when  a  bone  is  alternately 
moved  in  opposite  directions,  as  in  flexion  and  extension  ;  3.  The  movement  of  circum- 
duction, when  the  bone  which  is  in  motion  describes  a.  cone,  the  apex  of  which  is  at  the 
joint,  and  the  base  is  traced  by  the  opposite  end  of  the  bone  ;*  4.  The  movement  ofrotor 
tion,  in  which  a  bone  rolls  on  its  axis  without  changing  its  place. 

Proceeding  on  this  classification  of  the  movements,  Bichat  arranged  the  articulations 
in  two  great  classes,  the  movable  and  the  immovable.  The  latter  he  divided  accord- 
ing to  the  nature  of  the  articular  surfaces,  the  former  according  to  the  number  of  mo- 
tions, in  the  following  order  :  1st  class,  those  joints  which  are  capable  of  every  kind  of 
motion,  viz.,  gliding,  opposition,  rotation,  and  circumduction ;  2d  class,  those  joints  which 
are  capable  of  all  the  motions,  excepting  rotation  ;  3d  class,  those  joints  which  are  only 
capable  of  opposition,  or  alternate  motions  in  the  same  plane ;  ith  class,  those  joints 
which  admit  only  of  rotation  ;  5th  class,  those  joints  which  are  only  capable  of  a  gliding 
motion.     We  should  observe  that  gliding  occurs  in  all  the  preceding  forms  of  articulation. 

This  classification,  which  is  almost  exclusively  founded  upon  a  consideration  of  the 
movements,  is  eminently  physiological.  For  this  reason  we  shall  reject  it,  because,  in 
the  study  of  anatomy,  the  consideration  of  functions  is  of  secondary  importance,  com- 
pared to  that  of  structure.  The  motions  of  a  joint  are  also  evidently  the  consequence 
of  the  shape  of  its  articular  surfaces. 

The  classification  now  genercilly  adopted  is  that  of  Galen,  with  some  modifications. 
Taking  the  presence  or  absence  of  mobility  as  the  primary  ground  of  division,  the  artic- 
ulations are  divided  into  the  movable  or  diarthroses,  and  the  immovable  or  synarthroses. 
To  these  two  great  divisions  Winslow  has  added  a  third,  under  the  name  of  mixed  artic- 
ulations, or  amphiarthroses  {uji^u,  both),  because  they  partake  of  the  characters  of  both,, 
viz.,  mobility,  and  continuity  of  surfaces. + 

For  the  determination  of  the  secondary  divisions,  regard  h£is  been  had  both  to  tha 
shape  of  the  articular  surfaces,  and  to  the  movements  of  which  the  joint  is  capable. 

*  All  the  joints  which  possess  the  four  movements  of  opposition  necessarily  possess  those  of  etrcumcvuctton; 
t  This  kind  of  articulation  was  known  to  Galen,  and  named  by  him  neuter,  or  doubtful  articulation 

P 


1 14  ARTHROLOGY. 

Thus,  the  diarthroses  hare  been  subdivided  iiito,  1.  Enarthroses,  when  the  head  of  one 
bone  is  received  into  the  cavity  of  another ;  2.  Arthrodia,  when  the  articular  surfaces  are 
plane,  or  nearly  so ;  3.  Ginglymus,  when  the  joint  is  only  capable  of  opposition,  that  is, 
of  alternate  movements  in  opposite  directions  in  the  same  plane.  This  latter  class  is 
again  subdivided  into  (a)  angular  ginglymus  or  hinge-joints,  when  the  movements  are  an- 
gular, as  in  flexion  or  extension :  the  angular  ginglymus  is  said  to  be  perfect,  when  these 
movements  alone  are  possible,  as  in  the  elbow ;  and  imperfect,  when  a  slight  degree  of 
later2d  motion  may  take  place,  as  in  the  knee  :  (Jb)  lateral  ginglymus  (or  diarthrosis  tro- 
choides),  when  rotation  is  the  only  possible  movement.  It  also  is  subdivided  into  simple^ 
when  the  bones  touch  only  by  one  point ;  and  double,  when  they  have  two  points  of  contact. 

The  synarthroses,  or  immovable  joints,  have  been  divided,  according  to  the  nature  ot 
their  articular  surfaces,  into,  1.  Suture,  when  they  are  furnished  with  teeth,  by  means  ol 
which  they  are  locked  together,  as  in  the  squamous  suture ;  2.  Harmonia,  when  the  sur- 
faces are  nearly  smooth,  and  are  merely  in  juxtaposition ;  3.  Gomphosis,  when  one  part 
is  implanted  in  another,  as  the  teeth  in  the  alveoli ;  4.  Schindylesis,  when  a  plate  of  one 
bone  is  received  into  a  groove  of  another :  in  this  way  the  osseous  projection  of  the  an- 
terior edge  of  the  palate  bone  is  attached  to  the  opening  of  the  maxillary  sinus.* 

There  are  many  advantages  in  the  abov&  classification,  but  many  imperfections  also. 
I  would  characterize,  as  especially  objectionable,  the  class  arthrodia,  which  comprises 
the  most  dissimilar  articulations,  as  the  shoulder-joint,  the  articulations  of  the  lower 
jaw,  of  the  wrist,  of  the  bones  of  the  carpus,  and  of  those  of  the  tarsus.  We  should  als9 
notice,  as  another  cause  of  imperfection,  the  want  of  imity  in  the  basis  of  the  classifi- 
cation, which  is  sometimes  founded  upon  the  shape  of  the  surfaces,  sometimes  on  the 
motions. 

By  adopting  the  shape  of  the  articular  surfaces  alone  as  a  basis,  we  shall  find  the  ar- 
rangement of  the  ligaments  and  the  motions  to  be  in  some  measure  dependant  upon  this. 
On  this  principle,  we  shall  divide  all  the  joints  into  three  classes :  1.  The  diarthroses 
{diapdpovj),  or  those  which  are  formed  by  bones  the  surfaces  of  which  are  contiguous, 
but  free ;  2.  Synarthroses  {avv,  with),  or  all  the  joints  whose  surfaces  are  continuous ; 
3.  Amphiarthroses,  or  symphyses  (an<pu,  both),  or  those  joints  whose  surfaces  are  partly 
contiguous,  and  partly  continuous  by  means  of  fibrous  tissue. 

I.  Diarthroses. 

Characters. — Contiguous  or  free  articular  surfaces,  shaped  so  as  to  fit  exactly  upon 
each  other,  and  each  provided,  1.  With  an  incrusting  layer  of  cartilage  ;  2.  With  syno- 
vial membranes ;  3.  With  peripheral  ligaments ;  joints  always  movable.  This  class  is 
divided  into  six  subdivisions  : 

1.  Enarthrosis. 

Characters. — A  head,  or  portion  of  a  sphere,  more  or  less  completely  received  into  a 
cavity.     Examples  :  hip  and  shoulder  joints  (fig.  76,  and^«.  69  and  70). 

Ligaments. — A  fibrous  capsule. 

Motions. — In  every  direction ;  viz.,  flexion,  extension,  abduction,  adduction,  circumr 
duetion,  and  rotation. 

2.  Articulation  by  mutual  Reception. 

Characters. — Articular  surfaces,  concave  in  one  direction,  convex  in  the  direction  per- 
pendicular to  the  first,  and  so  fitted  as  to  embrace  each  other  reciprocally.  Example ; 
articulation  of  the  trapezium  with  the  first  metacarpal  bone  {m,fig.  75).  J 

Ligaments. — Two  or  four  ligaments,  or,  rather,  an  orbicular  or  capsular  ligament. 

Motions. — In  all  directions,  like  the  enarthroses,  excepting  rotation. 

3.  Articulation  by  Condyles,  or  Condylarthrosis. 

Characters. — An  elongated  head,  or  condyle,  received  into  an  elliptical  cavity.  Ex- 
amples :  articulation  of  the  forearm  and  hand  {fig.  75),  of  the  lower  jaw  and  the  temporal 
bone  {fig.  65). 

Ligaments. — Two  or  four  ligaments. 

Motions. — In  four  directions ;  viz.,  flexion,  extension,  abduction,  and  circumduction, 
but  no  rotation.  There  are  always  two  principal  movements  in  these  joints,  and,  con- 
sequently, two  which  are  limited. 

4.   Trochlear  Articulation,  or  Ginglymus. 
Characters. — A  mutual  reception  of  the  articular  surfaces.     The  pulley  or  trochlea 
belongs  to  this  mode  of  articulation.     Examples  :  the  elbow  {figs.  71  and  72),  the  knee 
{fig.  78),  the  joints  of  the  phalanges  {figs.  73  and  74). 

*  [The  rostrum  of  the  sphenoid,  and  the  descending  plate  of  the  ethmoid,  are  united  in  this  manner  to  the 
vomer,  and  afford,  perhaps,  a  better  example.] 

+  The  particle  Ita  always  signifies  separation. 

i  The  cervical  vrrtebrae  of  the  swan  present  a  beautiful  specimen  of  this  kind  of  articulation.  This  girei 
to  the  movements  of  the  neck  of  these  birds  that  elegance  and  grace  for  which  they  are  so  remarkable. 


ARTICULATIONS  OF  THE  VERTEBRAL  COLUMN.  Il6 

Ligaments. — ^Two  lateral  ligaments  generally  placed  nearer  the  side  of  flexion  than 
that  of  extension.  Sometimes  there  are  likewise  anterior  and  posterior  ligaments,  but 
they  are  always  weak,  and  are  often  replaced  by  tendons. 

Motions. — Two  motions  in  opposite  directions. 

5.   Trochoid  Articulations.* 

Characters. — An  axis  received  into  a  ring,  which  is  partly  osseous  and  partly  fibrous. 
Examples  :  articulation  of  the  atlas  and  axis  (c,  fig.  64),  of  the  radium  and  ulna  {figs.  71 
and  72). 

Ligaments. — ^An  annular  hgament. 

Motions. — Rotation. 

6.  Arthrodia. 

Characters. — Articular  surfaces,  plane,  or  nearly  so.t  Examples:  articulations  of  the 
carpal  and  tarsal  bones  {figs.  75  and  84),  and  of  the  articular  processes  of  the  vertebrae  {g,figs. 
61  and  63). 

Ligaments. — Fibres  placed  irregularly  round  the  joint. 

Motions. — Gliding. 

II.  Synarthroses. 

Characters. — Articular  surfaces  armed  with  teeth  or  other  inequalities,  which  are  mu 
tually  dovetailed,  and  from  which  the  name  of  suture  is  derived.  Examples  :  articular 
tions  of  the  bones  of  the  cranium  {figs.  21,  22,  and  23). 

Means  of  Union. — Remnant  of  the  cartilage  of  ossification,  which  is  gradually  en- 
croached on  during  the  progress  of  age.J 

There  are  no  incrusting  cartUages,  synovial  membranes,  ligaments,  nor  motions. 

Monro  enumerates  seven  kinds  of  sutures,  and  these  might  still  be  multiplied,  if  we 
regarded  all  the  varieties  presented  by  the  articular  surfaces.  Three  kinds  may  be  ad- 
mitted with  propriety:  1.  Indented  sutures;  2.  Squamous  sutures;  and,  3.  Harmonic  sv^ 
tares ;  the  distinctions  depending  upon  the  articular  surfaces  being  provided  with  teeth, 
or  overlapping  like  scales,  or  being  simply  rough  and  in  juxtaposition.  These  even  are 
only  unimportant  varieties.  Monro  added  the  schindylesis,  or  ploughshare  articulation 
of  Keil.  We  shall  content  ourselves  with  simply  mentioning  it ;  and  we  also  omit  the 
division  gomphosis  {yofK^oQ,  a  nail),  which  is  appropriated  to  the  mode  of  implantation  of 
the  teeth ;  because  the  teeth  are  not  bones,  and  are  lodged  in  the  jaw,  not  articulated 
with  it. 

III.  ^mphiarthroses,  or  Symphyses. 

Characters. — Flat,  or  nearly  flat,  articular  surfaces,  which  are  partly  in  contact,  and 
are  partly  continuous,  by  means  of  fibrous  tissue.  Examples  :  articulation  of  the  bodies 
of  the  vertebra  {b,  fig.  58),  symphysis  pubis  {e,  fig.  77),  sacro-iliac  symphysis  {b,  fig.  76). 

Means  of  Union. — Interosseous  and  peripheral  ligaments. 

Motion. — Very  slight,  gliding ;  an  arthrodia  is  a  necessary  element  of  an  amphiarthro- 
»is.    Thus,  in  the  symphysis  pubis  the  bones  are  partly  in  contact,  partly  continuous. 


ARTICULATIONS  OF  THE  VERTEBRAL  COLUMN. 

Articulations  of  the  Vertebrae  with  each  other. — Those  peculiar  to  certain  Vertebra:. — Sacro- 
vertebral,  Sacro-coccygeal,  and  Coccygeal  Articulations. — Articulations  of  the  Cranium — 
Of  the  Face — Of  the  Thorax. 

The  articulations  of  the  vertebral  column  {figs.  58,  59,  and  60)  are  divided  into  the 
extrinsic  and  the  intrinsic.  The  first  comprise  the  articulations  of  the  vertebral  column 
with  the  head,  the  ribs,  and  the  ossa  innominata.  The  intrinsic  comprise  the  articula- 
tions of  the  vertebrae  with  each  other.  These  last  are  also  divided  into  those  which  are 
common  to  all  the  vertebrae,  and  those  which  are  peculiar  to  some.  We  shall  describe 
each  in  succession. 

Articulations  of  the  Vertebrcs  with  each  other. 
Mode  of  Preparation. — Remove  completely  all  the  soft  parts  which  surround  the  ver- 
tebral column ;  saw  ofl!"  vertic2illy  all  that  part  of  the  head  which  is  in  front  of  the  column, 
and  separate  the  bodies  of  the  vertebra  from  the  posterior  arches  by  dividing  the  pedi- 
cles.    When  the  section  reaches  the  axis,  carry  the  instrument  behind  the  superior  ar- 

*  The  trochoid  (rpfx<u,  to  turn),  or  pivot-joint,  corresponds  to  the  simple  or  double  lateral  ginglymu*  of' 
modem  anatomists,  or  the  rotatory  diarthrosis  of  the  ancients. 

t  These  articular  surfaces  are  very  variable  in  the  arthrodial  articulations.  Sometimes  they  are  angular, 
sometimes  spheroidal.     As  respects  the  ligaments,  they  are  sometimes  loose,  sometimes  firm. 

t  Some  anatomists  have  rejected  this  kind  of  articulation,  adopting  the  opinion  of  Columbus,  who  affirms 
that  there  can  be  no  joint  whe'e  there  is  no  motion. 


116 


ARTHROLOGY. 


licular  processes  of  this  vertebra,  and  of  the  atlas,  and  behind  the  condyles  of  the  occipi- 
tal cone  :  remove  the  spinal  marrow^  and  its  membranes.  In  this  way  the  vertebral  col- 
umn will  be  divided  into  two  parts  :  an  anterior,  formed  by  the  series  of  the  bodies  of  the 
vertebra;,  on  which  we  find  the  anterior  and  posterior  common  ligaments,  and  the  interver- 
tebral substances ;  and  a  posterior,  formed  by  the  series  of  laminae,  and  the  articular  and 
sj)inous  processes.  The  intervertebral  substances  require  a  special  preparation,  which 
consists  in  making  vertical  and  horizontal  sections  of  a  portion  of  the  column,  or  which 
may  be  more  simply  effected  by  maceration  in  diluted  nitric  acid,  which  allows  the 
bodies  of  the  vertebra;  to  be  removed  without  injuring  the  intervertebral  substance. 
The  vertebrae  are  united,  1 .  By  their  bodies  ;  2.  By  their  articular  processes  ;  3.  By  their 
laminae ;  and,  4.  By  their  spinous  processes. 

Articulation  of  the  Bodies  of  the  Vertebra. 
The  bodies  of  the  vertebrae  are  united  together  by  amphiarthrosis.    The  arthrodial  por- 
tion, or  the  contiguous  surface,  is  represented  by  the  articular  processes. 

The  articular  surfaces  are  the  upper  and  under  surfaces  of  the  body  of  each  vertebra. 
It  follows,  from  the  concavity  of  these  surfaces,  that,  instead  of  fitting  each  other  exact- 
ly, they  leave  considerable  lenticular  spaces  between  them ;  these  appear  to  berfhe  ves- 
tiges of  the  biconical  cavity  between  the  vertebrae  of  fishes.  The  depth  of  these  spaces 
is  not  the  same  throughout  the  entire  column  ;  it  exactly  measures  the  thickness  of  the 
intervertebral  substance.  By  measurement,  I  have  afecertained  that  the  height  of  the  in- 
tervertebral substance  in  the  loins  is  one  half  of  that  of  the  bodies  of  the  vertebra,  in  the 
back  one  third,  and  in  the  neck  a  little  more  than  the  half  From  the  size  of  the  bodies 
of  the  vertebra,  it  follows  that  the  interval  between  the  bodies  is  largest  in  the  lumbar  re- 
gion. The  articular  surfaces  of  the  bodies  of  the  vertebra  are  covered  by  a  very  thin 
layer  of  cartilage  intermediate  between  the  bones  and  the  fibrous  tissues. 

The  means  of  union  are  of  two  kinds,  as  in  all  the  amphiarthroses  :  1.  They  surround 
the  joint ;  2.  They  proceed  from  one  articular  surface  to  the  other  :  in  one  word,  some 
are  peripheral,  and  the  others  interosseous. 

1.  Peripheral  Ligaments. — The  most  general  idea  which  can  be  formed  of  these  liga- 
ments is  that  of  a  fibrous  sheath,  surrounding  the  column  formed  by  the  bodies  of  the 
vertebrae,  and  uniting  in  one  whole  the  different  pieces  of  which  it  is  composed.  The 
part  of  the  sheath  which  covers  the  anterior  aspect  of  the  bones  is  called  the  anterior 
common  ligament  of  the  vertebra ;  and  that  which  covers  the  posterior  surface  is  called 
the  posterior  common  ligament  of  the  vertebra. 

The  anterior  common  vertebral  ligament  (a,  figs.  58,  60)  presents  the  appearance  of  a 
Fig.  58.  white  pearly-looking  membrane  stretched  from  the  axis  to  the 

upper  part  of  the  sacrum.  This  ligament,  which  is  thicker  in  the 
dorsal  region  than  in  the  neck  or  the  loins,  is  composed  of  three 
very  distinct  parts :  a  thick  one  in  the  middle,  and  two  lateral, 
which  are  separated  from  it  by  a  series  of  openings  that  give  pas- 
sage to  some  vessels  (see  fig.  58).  Its  anterior  surface  is  in  con- 
tact with  the  organs  of  the  neck,  the  thorax,  and  the  abdomen, 
and  united  with  them  by  very  loose  cellular  tissue.  The  tendons 
of  the  longi  colli  and  anterior  recti  muscles,  and  the  pillars  of  the 
diaphragm,  mix  their  fibres  with  this  ligament.  The  psoae  mus- 
cles correspond  to  its  lateral  portions  below.  Its  posterior  surface 
adheres  more  closely  to  the  intervertebral  substances,  and  to  the 
projecting  rims  of  the  bodies  of  the  vertebrae,  than  to  the  trans- 
verse grooves  of  the  bodies.  This  ligament  is  composed  of  sev- 
eral planes  of  fibres,  of  which  the  most  superficial  are  the  longest. 
The  deepest  pass  from  one  vertebra  to  the  next,  and  are  lost  on 
the  periosteum.    The  superficial  stretch  over  four  or  five  vertebrae. 

Posterior  common  vertebral  ligament  (a,  fig.  59).     This  is  thicker  than  the  anterior,  but 


(Fig.  59.) 


has  the  same  white  pearly  appearance.  It  commences  at  the  oc- 
cipital bone,  and  terminates  at  the  sacrum.  It  resembles  a  fibrous 
band,  which  expands  at  the  intervertebral  substances,  and  is  con- 
tracted over  the  bodies  of  the  vertebrae  ;  hence  it  has  a  regular  fes- 
tooned appearance.  Its  posterior  surface  is  united  to  the  dura  mater 
at  its  upper  part,  but  is  separated  from  it  by  a  dehcate  cellular  tis- 
sue throughout  the  rest  of  its  extent.  Its  anterior  surface  adheres 
intimately  to  the  intervertebral  substances  ;  it  is  separated  from 
the  middle  of  the  bodies  of  the  vertebra  by  the  veins,  which  pass 
from  the  interior  of  the  bone  into  the  vertebral  venous  sinuses 
which  run  along  the  edges  of  the  ligament.  Like  the  anterior  com- 
mon vertebral  ligament,  it  is  composed  of  several  planes  of  fibres, 
the  posterior  of  which  are  the  longest.  It  is  formed  of  more  com- 
pact tissue  than  the  anterior. 
2.  The  intervertebral  substance  or  interosseous  hgament  {b,  figs.  58, 


ARTICULATIONS    OP   THE   VERTEBRAL   COLUMN.  117 

59,  60,  and  68)  consists  of  a  kind  of  disc,  which  fills  up  the  lenticular  space  between  the 
bodies  of  the  vertebrae,  and  might,  with  propriety,  be  called  mtervertehrd.  disc. 

Each  disc  has  the  form  of  a  double  convex  lens,  and  is  so  closely  united  by  its  upper 
and  under  surfaces  to  the  corresponding  vertebra;,  that  it  is  easier  to  break  the  bones  than 
to  destroy  this  connexion.  Its  circumference  adheres  to  the  anterior  and  posterior  com- 
mon ligaments,  and  contributes  to  form  the  intervertebral  foramina.  In  the  dorsal  region 
it  also  forms  part  of  the  angular  facette  which  articulates  with  the  ribs.  The  thickness 
of  the  intervertebral  substance  is  not  the  same  in  all  the  regions  of  the  spinal  column,  be- 
ing greatest  at  the  lower  parts.  The  proportion  between  the  thickness  of  the  discs  and 
the  bodies  of  the  vertebrae  is  exactly  measured  by  that  of  the  intervertebral  space,  and  is 
not  the  same  in  all  the  regions.  In  the  lumbar  region  the  thickness  of  the  disc  is  half 
that  of  the  corresponding  vertebrae  ;  in  the  dorsal  region  it  is  a  third  ;  and  in  the  cervi- 
cal region  it  is  a  little  more  than  a  half* 

The  intervertebral  substance  is  not  equally  thick  throughout.  From  its  lenticular  form, 
it  must  be  thicker  at  the  centre  than  at  the  circumference  ;  in  the  neck  and  in  the  loins 
it  is  thicker  in  front  than  behind  ;  in  the  back  the  opposite  prevails,  and  by  this  inequality 
the  discs  concur  in  producing  the  alternate  curves  of  the  vertebral  column.  Abnormal 
curvatures  are  in  a  great  measure  caused  by  unequal  thickness  of  these  dies,  and  I  have 
often  had  opportunities  to  convince  myself  that  compression  of  this  substance  on  the  side 
towards  which  the  inclination  takes  place  is  the  most  common  origin  of  the  deformity. 
The  thickness  of  the  discs  varies  in  different  circumstances.  Thus,  after  prolonged 
standing  in  the  erect  posture,  the  height  of  the  body  becomes  diminished  from  eight  to 
ten  lines,  which  is  owing  to  compression  of  the  intervertebral  substances. 

Each  disc  is  composed  of  concentric  layers  (figs.  60  and  68)  closely  pressed  together 
at  the  circumference,  but  more  separate  towards  the  centre,  where  we  find  a  soft  spongy 
substance,  moistened  by  a  viscid  fluid  resembling  synovia.  This  soft  substance  is  nearer 
the  posterior  than  the  anterior  aspect  of  the  body  of  the  vertebra ;  it  escapes,  and  forms, 
as  it  were,  a  hernia,  when  the  parts  are  cut  either  horizontally  or  vertically.  It  varies 
much  at  different  ages.  It  is  moist,  soft,  spongy,  and  white  in  the  infant  and  in  youth, 
which  accords  with  the  suppleness  of  the  vertebral  column  at  that  period  of  life.  Where 
this  substance  is  situated,  we  may  inflate  an  irregular  cellular  cavity  in  it,  which  may  be 
regarded  as  the  rudiment  of  the  large  synovial  cavity  which  these  parts  exhibit  in  fishes. 
M.  Pailloux  believes  that  this  cavity  is  lined  by  a  synovial  membrane.  In  old  age  it  be- 
comes dry,  friable,  and  yellowish,  or  brown.  Monro  attributes  the  elasticity  of  the  ver- 
tebral column  to  the  displacement  of  this  soft  central  substance  in  the  different  move- 
ments ;  for,  according  to  his  theory,  the  movements  of  the  bodies  of  the  vertebrae  take 
place  upon  it  as  upon  a  movable  pivot  or  a  Uquid  fulcrum. 

The  intervertebral  substance  is  called  a  cartilaginous  ligament  by  Vesalius ;  by  others, 
a  cartilage  ;  and  by  Bichat,  a  Jibro-cartilage  ;  but  they  evidently  belong  to  the  fibrous  tis- 
sues. This  may  be  shown  by  macerating  a  portion  of  the  spinal  column  for  some  days, 
or  even  by  rubbing  the  surface  with  a  rough  cloth.  It  will  then  appear  that  this  pretend- 
ed fibro-cartilage  is  nothing  more  than  a  series  of  concentric  fibrous  layers,  strongly  com- 
pressed together ;  that  each  layer  is  formed  of  parallel  fibres,  directed  very  obliquely 
from  the  lower  surface  of  the  vertebra  above  to  the  upper  surface  of  the  vertebra  below, 
and  regularly  crossing  with  the  fibres  of  the  next  layer  {¥,  fig.  58).  This  regular  cross- 
ing, which  we  shall  meet  with  in  other  parts,  is  evidently  very  conducive  to  solidity. 

Union  of  the  Articular  Processes. 

These  articulations  are  arthrodice. 

Articular  Surfaces. — The  corresponding  surfaces  are  covered  by  a  thin  layer  of  cartilage. 
The  means  of  union  consist  of  some  irregular  ligamentous  fibres  {d  d,  fig.  60),  which  sur- 
round the  outside  of  the  joint,  and  are  more  numerous  in  the  dorsal  and  cervical  regions 
than  in  the  loins,  the  internal  side  of  the  articulation  being  occupied  by  the  yellow  liga- 
ment. These  articulations  are  provided  with  synovial  membranes  of  greater  extent  in 
the  cervical  than  in  the  other  regions. 

Union  of  the  LamincB.  ^_  60. 

The  spaces  between  the  vertebral  laminae  are  occupied  by  ligaments  of 
a  particular  description,  which  are  called  yellow  ligaments,  ligamenta  suh- 
flava,  on  account  of  their  colour.  They  are  composed  of  two  halves  uni- 
ted at  an  angle  like  the  laminae  (c  c,fig.  60).  Their  lower  edge  is  implanted 
upon  the  upper  edge  of  the  laminae  below,  and  their  upper  edge  is  attached 
to  the  anterior  surf£ice  of  the  corresponding  laminae.  From  this  it  fol- 
lows, that  the  height  of  the  ligamenta  subflava  is  much  greater  than  would 
be  necessary  to  reach  from  one  lamina  to  another ;  it  is  almost  equal 
to  that  ol  the  corresponding  vertebral  lamina. 

Their  length  is  measured  by  that  of  the  laminae,  and  is,  consequently, 

*  A  curious  preparation  may  be  made  by  taking  away  all  the  bodies  of  the  vertebrae  in  a 
spine  softeced  by  nitric  acid.  A  column  then  remains,  formed  by  the  series  of  discs,  which 
may  be  compared  with  a  column  formed  by  the  bodies  of  the  vertebra;. 


118  ARTHROLOGY. 

greater  in  the  neck  than  in  the  back  and  loins.  They  are  of  greater  thickness  in  the 
loins  than  in  the  back  and  the  neck,  and  the  thickest  part  corresponds  to  the  base  of  the 
spinous  process.  There  are  also  some  re-enforcing  bundles,  which  constitute  a  sort  of 
median  yeUow  ligament.  Their  anterior  surface  is  separated  from  the  dura  mater  by  cel- 
lular tissue,  and  by  veins.  It  is  remarkable  for  its  smooth  and  polished  appearance. 
Their  posterior  surfaces  are  in  contact  with  the  vertebral  laminae,  which  cover  them  al- 
most completely,  except  in  the  cervical  region,  where  they  may  be  seen  between  the  lam- 
inae, when  the  head  is  slightly  inclined  forward ;  this  circumstance  renders  it  possible 
lor  a  penetrating  instrument  to  enter  between  the  cervical  laminae,  while  it  is  almost 
impossible  in  the  dorsal  and  lumbar  regions. 

Structure. — These  ligaments  are  composed  of  parallel  vertical  fibres  very  closely  ar- 
ranged. They  are  extensible,  and,  when  stretched,  immediately  recover  themselves,  and 
are  therefore  very  elastic.  They  are  as  strong  as  ordinary  ligaments.  Their  extensi- 
bility is  brought  into  action  during  flexion  of  the  vertebral  column,  and  their  elasticity 
during  extension.  They  have  great  effect  in  maintaining  the  erect  posture,  which  would 
otherwise  have  required  a  constant  expenditure  of  muscular  power. 

Union  of  the  Spinous  Processes. 

The  spinous  processes  are  united  by  the  supra-spinous  and  the  inter-spinous  ligaments. 
The  supra-spinous  ligament  {d  d,  figs.  58  and  59)  is  a  fibrous  cord,  which  extends  from  the 
seventh  cervical  vertebra  to  the  sacrum,  along  the  summit  of  the  spinous  processes  of 
the  dorsal  and  lumbar  vertebrae.  This  ligament  can  be  only  distinguished  from  the 
aponeurotic  fibres,  which  are  inserted  into  the  spinous  processes,  by  the  longitudinal  di- 
rection of  its  fibres.  It  is  larger  in  the  lumbar  than  in  the  dorsal  region.  It  is  expand- 
ed, and  becomes  even  sometimes  cartilaginous  in  the  interval  between  the  processes. 
It  is  inextensible.  I  regard  a  fibrous  cord  which  extends  from  the  seventh  cervical  ver- 
tebra to  the  external  occipital  protuberance  as  a  continuation  of  the  supra-spinous  liga- 
ment ;  it  appears  to  be  the  vestige  of  the  posterior  cervical  ligament  of  quadrupeds,  and  is 
of  considerable  size  in  some  subjects  ;  from  its  anterior  surface,  prolongations  a\^  given 
off  to  the  spinous  processes  of  all  the  cervical  vertebrae,  excepting  the  first.* 

The  inter-spinous  ligaments  (e  e,  Jig.  58)  do  not  exist  in  the  neck,  where  their  place  is 
suppUed  by  small  muscles  ;  they  are  very  thin  in  the  back,  where  each  has  the  form  of  a 
triangle  with  the  base  looking  backward.  They  are  thick  and  quadrilateral  in  the  loins. 
Their  upper  and  lower  edges  are  attached  to  the  corresponding  spinous  processes.  Their 
surfaces  are  in  contact  with  the  muscles  of  the  vertebral  grooves.  M.  Mayer  speaks  of 
synovial  capsules,  which  he  has  met  with  between  the  lumbar  spinous  processes,  and 
especially  between  the  third  and  the  fourth  in  this  region ;  these  membranes  are  by  no 
means  constant. 

Articulations  peculiar  to  certain  Vertebra  (Jigs.  61  to  64). 

Although  the  articulations  of  the  atlas  and  of  the  axis,  with  the  occipital  bone,  do  not 
properly  belong  to  the  articulations  of  the  vertebral  column,  yet  the  connexion  between 
these  articulations  and  that  of  the  atlas  with  the  axis  is  so  intimate,  that  it  is  impossi- 
ble to  separate  them.  We  shall  describe  these  three  articulations  in  succession ;  first 
noticing  the  articulation  of  the  atlas  with  the  occipital  bone  {occipito-atlantoid  articulation). 

Occipito-atlantoid  Articulation. 

Preparation. — Remove  the  part  of  the  scull  which  is  in  front  of  the  vertebral  column, 
taking  care  to  leave  the  basilar  process.  The  muscles  which  surround  the  joint,  being 
closely  applied  to  the  ligaments,  should  be  very  carefully  detached. 

The  atlas  unites  with  the  occipital  bone,  1 .  By  its  anterior  arch ;  2.  By  its  posterior 
arch ;  3.  By  the  base  of  its  transverse  processes ;  4.  By  its  two  articular  surfaces. 
1.  The  anterior  arch  of  the  atlas  is  united  to  the  circumference  of  the  foramen  mag- 
„.    g.  num  by  two  anterior  occipito-atlantal  ligaments.     One 

*^'     ■  of  these,  the  superficial  (a,  figs.  61  and  64),  is  a  very 

strong  cylindrical  cord  situated  in  the  median  line, 
where  it  forms  a  very  marked  projection,  and  stretches 
from  the  basilar  process  of  the  occipital  bone  to  the  an- 
terior tubercle  of  the  atlas.  The  other  (i,  fig-  61), 
which  is  deep-seated,  is  pretty  thick,  consists  of  several 
layers,  and  extends  from  the  upper  edge  of  the  anterior 
arch  of  the  atlas  to  the  occipital  bone. 

2.  Most  anatomists  admit  the  existence  of  a  liga 
ment  stretching  from  the  posterior  part  of  the  foramen 
magnum  to  the  upper  edge  of  the  posterior  arch  of  the 
atlas,  the  posterior  occipito-atlantal  ligament  (b,  figs.  62 

*  This  ligament  is  the  result  of  the  intersection  of  the  aponeuroses,  of  the  trapezius,  splenius,  &c.  I  shall 
»fer  more  particularly  to  this  point  in  myology,  when  on  the  subject  of  the  posterior  cervical  apoueiirosis 


ARTICULATIONS  OF   THE   VERTEBRAL   COLUMN. 


119 


and  64).    But  it  can  scarcely  be  distinguished,  con-  Fig.  62. 

sisting  only  of  a  {ew  ligamentous  fibres  among  the 
fat  of  this  region. 

3.  Lateral  Occipito-atlantal  Ligaments  (c,  jig.  61). 
— A  fibrous  cord  passes  from  the  base  of  the  trans- 
verse process  of  the  atlas  to  the  jugular  process  of 
the  occipital  bone.  In  connexion  with  a  similar  bun- 
dle from  the  pars  petrosa,  it  forms  a  very  remark- 
able fibrous  canal,  which  gives  passage  to  the  in- 
ternal jugular  vein,  the  internal  carotid  artery,  the 
hypoglossal,  pneumogastric,  glosso-pharyngeal,  and 
accessory  nerves. 

4.  The  union  of  the  condyles  of  the  occipital  bone  with  the  superior  articular  surfaces 
of  the  atlas  is  a  double  candy  laid  articulation.  The  articular  surfaces  of  the  occipital  bone 
are  the  two  condyles,  convex,  oblong,  looking  downward  and  outward,  and  directed  for- 
ward and  inward,  so  that  their  axes,  if  prolonged,  would  meet  in  front  of  the  basilar 
process.  The  articular  surfaces  of  the  atlas  are  concave  and  oblong,  and  look  upward 
and  a  little  inward,  so  as  to  fit  exactly  upon  the  convexity  of  the  condyles.  Both  are 
covered  by  a  thin  layer  of  cartilage.  The  ligaments  are  vertical  fibres  which  surround  the 
joint,  but  are  most  numerous  in  front  and  on  the  outside,  for  they  scarcely  exist  on  the 
mside  and  behind.  There  is  also  a  very  loose  synovial  membrane  which  passes  beyond 
^he  articular  surfaces  on  all  sides,  but  especially  to  the  outside. 

Atlanto-axoid  Articulation. 

Preparation. — After  having  studied  the  superficial  ligaments,  remove  the  laminae  of  the 
axis,  the  posterior  arch  of  the  atlas,  and  the  back  part  of  the  foramen  magnum.  Detach 
with  care  that  portion  of  the  dura  mater  which  corresponds  to  the  first  two  vertebrae  and 
the  foramen  magnum,  and  turn  it  upward.  Lastly,  in  order  to  obtain  a  good  view  of  the 
articulation  of  the  odontoid  process  with  the  atlas,  disarticulate  the  occipital  bone. 

This  articulation  is  formed  between,  1.  The  odontoid  process  of  the  axis,  and  the  an- 
terior arch  of  the  atlas  ;  2.  Between  the  superior  articulating  processes  of  the  axis  and 
the  inferior  articulating  processes  of  the  atlas  ;  3.  In  addition,  the  anterior  and  posterior 
arches  of  the  atlas  are  united  to  the  Jixis  by  two  hgaments — the  anterior  and  the  poste- 
rior atlanto-axoid  ligaments. 

The  anterior  atlanto-axoid  ligament  {b,figs.  61  and  64)  is  a  thick  vertical  bundle  com- 
posed of  several  layers,  which  extends  from  the  tubercle  and  the  lower  edge  of  the  an- 
terior arch  of  the  atlas  in  front  of  the  base  of  the  odontoid  process  of  the  body  of  the  axis. 
It  is  continuous  below  with  the  anterior  common  ligament. 

The  posterior  atlanto-axoid  ligament  (c,figs.  62  and  64)  is  a  very  loose  and  thin  mem- 
brane, extending  from  the  posterior  arch  of  the  atlas  to  the  upper  edge  of  the  laminae  of 
the  axis ;  it  is  a  little  thicker  in  the  median  hue  than  at  the  sides,  and  represents  the 
ligamenta  subflava  in  a  rudimentary  state. 

Articulation  of  the  Odontoid  Process  with  the  Atlas. — This  is  aywof  joint,  the  odontoid  pro- 
cess being  received  into  a  ring  formed  in  front  by  the  anterior  arch  of  the  atlas,  on  the 
sides  by  the  lateral  masses  of  the  same  bone,  and  behind  by  the  transverse  ligament. 
We  have,  therefore,  to  consider,  1.  The  articulation  of  the  anterior  arch  of  the  atlas  with 
the  odontoid  process  (atlanto-odontoid  articulation) ;  2.  The  articulation  of  this  same  pro- 
cess with  the  transverse  ligament  (syndesmo-odontoid  articulation). 

1.  Atlanto-odontoid  Articulation  (e,  fig.  64). — The  articular  surfaces  are  an  oval  and 
slightly  concave  facette  on  the  posterior  surface  of  the  anterior  arch  of  the  atlas  (1); 
and  a  slightly  convex,  vertically  oblong  facette,  on  the  fore  part  of  the  odontoid  process 
(2).  Both  surfaces  are  incrusted  with  cartilage,  and  there  is  also  a  very  loose  synovial 
membrane  with  subjacent  adipose  tissue.  The  joint  is  strengthened  by  some  hgament- 
ous  fibres,  arranged  in  the  form  of  a  capsule. 

2.  Syndesmo-odontoid  Articulation. — ^This  joint  is  formed  by  means  of  the  transverse  or 


Fig.  63. 


annular  ligament  (/,  figs.  63  and  64),  a  very  thick  and 
compact  bundle  of  fibres,  flattened  before  and  behind, 
and  stretched  transversely  between  the  lateral  masses 
of  the  atlas,  passing  behind  the  odontoid  process,  and 
closely  embracing  it  like  a  half  ring.  The  anterior  sur- 
face of  this  hgament  is  concave,  and  polished  like  car- 
tilage ;  it  is  in  contact  with  the  posterior  surface  of 
the  odontoid  process  (2,  fig.  64),  which  is  covered  with 
cartilage,  and  is  almost  always  furrowed  transversely, 
i.  e.,  in  the  direction  of  its  movements.  There  is  a  very 
loose  synovial  membrane  in  this  joint,  which  is  prolonged  on  the  sides  of  the  odontoid 
process,  as  far  as  the  odontoid  ligaments.  The  posterior  surface  is  covered  by  the  pos- 
terior occipito-axoid  ligaments*  (o,  fig  64 ;  see  figs.  63  and  64).     From  its  upper  edge  a 

*  If  the  student  is  only  provided  with  one  preparation  for  the  examination  of  all  these  joints,  it  is  necessary 
«o  study  these  ligament*  before  dividing  them,  in  order  to  expose  the  transverse  lig-aiuenls. 


120  ARTHROLOGY. 

fibrous  band  is  detached,  which  is  fixed  to  the  occipital  bone,  in  front  of  the  occipito-ax- 
oid  ligament,  by  a  narrow  extremity.  Another  fibrous  band  (see  jigs.  63  and  64),  of 
greater  length  than  breadth,  proceeds  from  its  lower  edge,  and  is  attached  to  the  postenor 
surface  of  the  axis  ;  hence  the  name  crucial  has  been  given  to  the  annular  ligament  by 
some  authors.  The  extremities  are  inserted  into  two  tubercles  on  the  inside  of  the 
lateral  masses  of  the  atlas. 

There  is  a  very  remarkable  circumstance  connected  with  this  ligament,  viz.,  that  its 
lower  circumference  belongs  to  a  smaller  circle  than  its  iipper,  so  that  the  odontoid  process 
is  very  firmly  retained  in  the  ring  which  this  ligament  contributes  to  form,  and  this  ar- 
rangement accords  with  a  sort  of  constriction  at  the  base  of  the  odontoid  process. 

Union  of  the  Articular  Processes  of  the  Atla^  and  the  Axis. 
This  is  a  double  arthrodia.  The  articular  stirfaces  of  the  atlas  are  plane,  circular,  and 
horizontal,  but  looking  slightly  inward  ;  those  of  the  axis  are  also  plane  and  horizontal, 
looking  slightly  outward,  and  of  greater  extent  than  the  preceding.  They  are  retained 
in  their  place  by  a  fibrous  capsule  ig,figs.  61  and  63),  which  is  very  strong,  especially  in 
front,  and  sufficiently  loose  to  permit  the  extensive  motions  which  take  place  at  this 
joint :  it  is  formed  of  vertical  and  parallel  fibres.  The  synovial  ca-psule  is  very  loose,  and 
projects  beyond  the  surfaces  of  the  bones  in  every  direction,  but  particularly  in  front.  It 
almost  always  communicates  with  the  synovial  membrane  of  the  joint  between  the 
transverse  ligament  and  the  odontoid  process. 

Union  of  the  Occipital  Bone  and  the  Axis. 

Although  the  occipital  bone  and  the  axis  are  nowhere  contiguous,  and  are  not,  there- 
fore, articulated,  yet  they  are  united  very  firmly  by  means  of  strong  ligaments,  extending 
from  the  occipital  bone  to  the  body  of  the  axis,  and  also  to  the  odontoid  process. 

Preparation. — Remove  with  care  that  portion  of  the  dura  mater  which  corresponds  to 
the  first  two  vertebrae ;  the  occipito-axoid  ligaments  lie  under  it.  Then  detach  the 
transverse  ligaments,  remove  the  anterior  arch  and  lateral  masses  of  the  atlas,  so  that 
nothing  remains  excepting  the  occipital  bone  and  the  axis. 

1.  The  occipito-axoid  ligaments  are  three  in  number,  a  middle  and  two  lateral.     The 
Ftg.  64.  middle  occipito-axoid  ligament  (o,  fig.  64)  is  thick,  and  forms 

at  its  upper  part  a  single  band,  the  fibres  of  which  are  sep- 
arated below  into  three  very  distinct  layers.  The  most 
posterior  of  these  is  continuous  with  the  posterior  common 
ligament ;  the  second  is  attached  to  the  posterior  surface 
of  the  body  of  the  axis ;  and  the  deepest,  which  is  very 
thin,  and  shaped  like  a  tongue  pointed  above,  is  that  which 
we  described  with  the  transverse  ligament.  The  lateral 
occipito-axoid  ligaments  (r,  fig.  64)  arise  from  the  sides  of 
the  basilar  groove  by  a  broad  extremity,  and  are  attached 
to  the  posterior  surface  of  the  axis  by  a  pointed  end.   They 

correspond  in  front  with  the  odontoid  and  transverse  ligaments,  and  behind  with  the 

dura  mater. 

2.  The  odontoid  ligaments  are  three  in  number,  a  middle  and  two  lateral.  The  middle 
(I,  fig.  64)  consists  of  ligamentous  fibres,  which  extend  from  the  apex  of  the  odontoid 
process  to  the  fore  part  of  the  foramen  magnum,  between  the  condyles  ;  the  two  lateral 
(I,  fig.  63)  are  two  bundles  of  fibres,  very  strong,  short,  and  cylindrical,  which  stretch 
between  the  sides  of  the  apex  of  the  odontoid  process,  and  two  small  fossae  on  the  inside 
of  the  condyles  ;  their  direction  is  horizontal,  so  that  they  represent  the  horizontal  limbs 
of  the  letter  T,  of  which  the  odontoid  process  forms  the  vertical  portion  ;  they  are  almost 
always  united  by  a  bundle,  which  passes  above  the  odontoid  process  without  adhering  to 
it,  so  that,  at  first  sight,  they  might  be  declared  to  be  one  and  the  same  ligament. 

Sacro'Vertebral,  Sacro-coccygeal,  and  Coccygeal  Articulations. 

Sacro-vertebral  Articulation. — This  resembles  in  every  point  the  articulations  of  the 
other  vertebra;.  We  shall  only  remark,  1 .  The  great  thickness  of  the  intervertebral  sub- 
stance, particularly  in  front,  a  vertical  section  of  it  resembling  a  hatchet  with  the  broad 
part  turned  forward ;  2.  The  sacro-vertebral  ligament  {a,  fig.  76),  which  is  proper  to  this 
articulation,  a  very  short,  thick,  and  strong  bundle  stretched  obliquely  from  the  trans- 
verse process  of  the  fifth  lumbar  vertebra  to  the  base  of  the  sacrum,  where  it  crosses 
with  some  ligamentous  fibres  of  the  sacro-iliac  articulation. 

Sacro-coccygeal  Articulation. — This  is  an  amphiarthrosis,  or  symphysis,  analogous  in 
every  repect  to  that  of  the  bodies  of  the  vertebrae  ;  a  fibrous  disc  resembling  the  inter- 
vertebral substances,  but  of  a  more  loose  texture,  unites  the  corresponding  articular  sur- 
faces. In  some  subjects  the  coccjrx  is  very  movable,  and  there  is  a  synovial  capsule  in 
the  centre  of  the  disc.  The  other  means  of  union  are,  1.  The  anterior  sacro-coccygeal  lig- 
ament {a  fig.  77),  composed  of  parallel  fibres  extending  from  the  anterior  surface  of  the 
sacrum  to  the  anterior  surface  of  the  coccyx,  and  often  divided  into  two  lateral  bundles  ; 


MECHANISM   OF   THE   VERTEBRAL   COLUMN.  121 

2.  The  posterior  sacro-coccygeal  ligament,  which  is  fixed  above  to  the  edges  of  the  notch 
which  terminates  the  sacral  canal,  and  is  prolonged  upon  the  posterior  surface  of  the 
coccyx.  This  ligament,  which  completes  the  sacral  canal,  gives  attachment  to  the  glu- 
taei  maximi  muscles  by  its  posterior  surface.  It  is  composed  of  several  layers,  the  most 
superficial  of  which  reach  the  apex  of  the  coccyx,  while  the  deepest  extend  only  to  the 
first  piece  of  that  bone. 

The  coccygeal  articulations  are  also  amphiarthroses,  which  become  synarthroses  during 
the  progress  of  life.     The  articulation  of  the  first  with  the  second  piece  is  the  only  one 
.  which  remains  to  an  advanced  age.     It  is  sometimes  extremely  movable.* 

Mechanism  of  the  Vertebral  Column. 
The  vertebral  column  being  at  once  an  enclosing  and  protecting  cylinder  for  the  spi- 
nal marrow,  a  column  for  transmitting  the  weight  of  the  trunk  and  the  upper  extremi- 
ties to  the  legs,  and  an  organ  of  locomotion,  its  anatomical  structure  must  be  examined 
in  reference  to  these  three  uses. 

The  Vertebral  Column  considered  as  the  Protecting  Cylinder  of  the  Spinal  Cord. 
The  vertebral  column  performs  the  office  of  a  protecting  cylinder,  by  virtue  of  its  so- 
lidity, ensured  by  the  bodies  of  the  vertebrae  in  front,  by  the  projection  of  the  spinous 
processes  behind,  which  ward  off,  so  to  speak,  all  external  objects,  and  by  the  promi- 
nence of  the  transverse  processes  at  the  sides.  By  means  of  these  arrangements,  the 
spinal  cord  is  inaccessible,  excepting  by  a  sharp  instrument,  which  might  penetrate  ei- 
ther in  front  through  the  intervertebral  substances,  or  on  the  sides  through  the  interver- 
tebral foramina,  or,  lastly,  behind  through  the  intervals  between  the  spinous  processes, 
and  between  the  laminae.  Another  condition  of  solidity,  in  so  far  as  this  can  be  obtain- 
ed with  mobility,  is  provided  by  the  number  of  pieces  of  which  the  vertebral  column  is 
formed.  For,  in  all  cases  where  the  column  is  subjected  to  shocks,  each  articulation 
becomes  the  seat  of  a  decomposition  of  the  force ;  a  part  is  employed  in  producing  a 
slight  displacement  of  the  articular  surfaces,  and  is  therefore  entirely  lost,  as  far  as  re- 
gards the  transmission  of  the  shock.  If,  on  the  contrary,  the  vertebral  column  had  been 
formed  of  one  single  piece,  the  transmission  of  shocks  would  have  been  unbroken,  and 
thus  the  frequent  cause  of  concussion  and  fracture.  Lastly,  the  breadth  of  the  articular 
surfaces  by  which  the  bodies  are  united,  the  strength  and  pliability  of  the  intervertebral 
substances,  the  vertical  direction  of  the  articular  processes,  contrasted  with  the  horizon- 
tal direction  of  the  articular  surfaces  of  the  body,  and  the  species  of  dovetailing  which 
results  from  it,  are  also  most  favourable  conditions  for  the  protection  of  the  spinal  mar- 
row. Indeed,  I  do  not  see  how,  in  our  system  of  organization,  the  protection  to  the  spi- 
nal cord  could  be  increased. 

•  The  Vertebral  Column  considered  as  an  Organ  for  transmitting  the  Weight  of  the  Trunk 
The  anatomical  arrangements  adapted  to  this  purpose  are  the  following : 

1.  The  progressive  increase  in  size  of  the  vertebral  column,  from  the  apex  to  the  base. 
This  disposition  is  particularly  observable  in  the  first  two  pieces  of  the  sacrum,  which 
are  proportionally  much  larger  in  man  than  in  the  lower  animals. 

2.  The  articulation  of  the  vertebral  column  with  the  posterior  part  of  the  pelvis,  by 
which  the  centre  of  gravity  of  the  trunk  is  carried  backward,  and  the  maintenance  of 
the  equilibrium  is  aided,  by  counterbalancing  the  weight  of  the  thoracic  and  abdominal 
viscera,  which,  instead  of  uniformly  surrounding  the  column,  are  all  placed  in  front. 

3.  The  alternate  inflections  of  the  vertebral  column,  which  allow  more  extensive  os- 
cillations of  the  centre  of  gravity  of  the  column  than  would  have  been  practicable  held 
its  direction  been  altogether  rectilinear,  and  which  also  augment  its  power  of  resistance 
in  the  vertical  direction. 

4.  The  length  of  the  spinous  processes,  which  thus  afford  a  more  favourable,  because 
a  longer  lever  to  the  extensor  muscles,  which  maintain  the  column  erect.  The  absence 
of  these  processes  in  infancy  is  one  of  the  causes  of  the  difficulty  of  standing  at  that  period. 

5.  The  existence  of  the  soft  matter  in  the  centre  of  the  intervertebral  discs,  which 
prevents  compression  of  the  column  by  affording  a  liquid,  and  therefore  almost  incom- 
pressible point  d'appui,  as  Monro  has  remarked  ;  the  truth  of  this  may  be  proved  by  sub- 
mitting a  portion  to  powerful  compression.  We  have  before  remarked  that  this  soft 
matter  is  not  placed  in  the  centre,  between  the  bodies  of  the  vertebra,  but  nearer  to  the 
posterior  border,  and,  consequently,  it  occupies  the  centre  of  their  movements.  It  di- 
minishes the  violence  of  shocks,  changes  its  position  as  we  change  our  attitudes,  and  fills 
up  the  vacancies  resulting  from  the  approach  of  the  bodies  on  one  side,  and  their  separa- 
tion on  the  other.  It  is  generally  believed,  it  is  true,  that  the  diminution  of  height  which 
follows  upon  prolonged  standing  or  walking  is  the  result  of  mechanical  compression  of 
the  intervertebral  discs,  and  an  absolute  diminution  of  their  thickness ;  but  it  appears 

*  I  have  met  with  an  instance  in  which  this  joint  was  very  movable  :  there  was  a  synovial  membrane  ana 
a  fibrous  capsule.  The  extent  of  the  motion  was  so  great,  that  the  two  pieces  could  be  made  to  form  a,  ngut 
angle  with  the  cavity  looking  backward. 

Q 


122  ARTHROLOGY. 

more  conformable  to  the  laws  of  physics  to  admit  that  the  diminution  in  the  height  of 
the  vertebral  column  depends  upon  the  increase  of  the  curvatures,  unless  we  admit  Mon- 
ro's hypothesis  of  the  absorption  of  part  of  the  hquid  contained  within  the  discs. 

6.  The  presence  of  the  yellow  ligaments,  which,  by  their  elasticity,  continually  oppose 
the  causes  which  tend  to  bend  the  body  forward,  and  which  are  for  each  of  the  vertebrae 
what  the  posterior  cervical  ligament  is  for  the  head. 

7.  The  existence  of  the  vertebral  canal,  which  has  the  same  advantage  as  the  cylinder 
of  long  bones,  of  increasing  the  strength  without  increasing  the  weight. 

8.  The  mode  of  articulation  of  the  vertebral  column  with  the  head,  which  is  doubly  ad- 
vantageous, both  as  regards  the  place  occupied  by  the  articular  surfaces,  and  their  di- 
rection:  1.  The  articular  surfaces  correspond  to  the  point  of  junction  of  the  posterior 
with  the  two  anterior  thirds  of  the  head.  The  posterior  third  of  the  head  contains  a 
large  portion  of  the  encephalic  mass,  while  the  two  anterior  thirds  are  chiefly  formed  by 
the  face,  which,  in  comparison  to  its  size,  is  of  little  weight.  From  this  it  follows,  that 
the  weight  of  the  posterior  third  almost  counterbalances  that  of  the  two  anterior  thirds 
of  the  head.  2.  The  almost  horizontal  direction  of  the  condyles  in  the  human  subject 
permits  the  head  to  rest  upon  the  summit  of  the  vertebral  column,  without  having  a 
necessary  tendency,  or  at  least  a  very  slight  one,  to  incline  forward,  as  invariably  takes 
place  in  animeds  whose  occipital  condyles  are  vertical,  and  situated  entirely  on  the  back 
of  the  head.  Yet,  notwithstanding  these  advantageous  conditions  of  the  atlantal  artic- 
ulation, the  part  in  front  of  the  condyles  is  somewhat  heavier  than  that  behind  ;  and  this 
difference,  though  slight,  is  sufficient  to  cause  flexion  of  the  head,  when  left  to  itself, 
either  during  sleep  or  after  death.  Indeed,  in  spite  of  all  the  arrangements  above  re- 
ferred to,  considerable  efforts  are  required  to  maintain  the  biped  position ;  and  to  secure 
this,  we  have  the  vertebral  grooves  filled  up  with  powerful  muscles.  In  the  human  sub- 
ject, the  muscles  which  occupy  the  cervical  portion  of  the  column,  and  which  are  des- 
tined to  support  the  head,  are  not  nearly  so  strong  as  the  corresponding  muscles  in  the 
quadruped,  while  those  of  the  loins  are  proportionally  much  stronger.  Standing  in  the 
erect  position  is,  therefore,  very  far  from  being  a  state  of  rest,  and  requires  a  constant 
muscular  effort  to  sustain  it. 

The  Vertebral  Column  considered  as  an  Organ  of  Locomotion. 

The  vertebrae  perform  upon  each  other  certain  oscillatory  or  balancing  movements  in 
all  directions,  by  means  of  the  pliability  of  the  intervertebral  substances  ;*  but  they  are 
so  obscure,  that  their  existence  can  scarcely  be  recognised,  or  their  character  examined 
on  a  small  portion  of  the  column.  In  order  to  understand  them,  the  entire  spine  must 
be  examined. 

Movements  of  the  entire  Column. — These  are,  1.  Flexion,  or  the  movement  forward.  2. 
Extension.  3.  Lateral  inclination.  4.  Circumduction,  in  which  the  column  describes  a 
cone,  of  which  the  apex  is  below,  and  the  base  above.  5.  Rotation  on  its  axis,  or  tor- 
sion of  the  vertebral  column. 

In  the  analysis  of  the  motions  of  the  column,  it  is  necessary  to  distinguish  carefully 
between  the  actual  and  the  apparent  motions ;  the  first  are  much  less  extensive  than 
would  be  imagined  at  first  sight,  the  greater  part  of  the  apparent  movements  taking  place 
at  the  articulations  of  the  pelvis  with  the  thighs.  In  these  movements  of  the  whole,  the 
column  represents  a  lever  of  the  third  order,  an  elastic  arch  in  which  the  resistance  is  at 
the  upper  extremity,  the  fulcrum  at  the  lower  end,  and  the  power  applied  in  the  middle. 
Each  vertebra,  on  the  contrary,  represents  a  lever  of  the  first  order,  in  which  the  pow- 
er and  the  resistance  are  at  the  anterior  and  posterior  extremities  of  the  bone,  and  the 
fulcrum  in  the  middle. 

1.  In  the  movement  of  flexion,  which  is  the  most  extensive  of  all,  the  anterior  common 
ligament  is  relaxed ;  the  anterior  part  of  the  intervertebral  substances  is  compressed  ; 
the  soft  central  portion  is  pushed  backward  ;  the  posterior  fibres  of  the  discs  are  shght- 
ly  stretched,  as  are  also  the  posterior  common  ligament,  the  supra-spinous,  inter-spi- 
nous,  and  yellow  ligaments.  The  inferior  articular  processes  of  each  vertebra  move  up- 
ward upon  the  superior  articular  processes  of  the  vertebra  below.  The  laminae  are  sep- 
arated, so  that  the  rachidian  canal,  especially  in  the  cervical  region,  becomes  accessible 
to  penetrating  instruments. 

2.  In  extension,  the  anterior  common  ligament  and  the  anterior  fibres  of  the  intei  ver- 
tebral discs  are  stretched  ;  the  posterior  fibres  of  the  disc  are  relaxed  ;  the  soft  central 
matter  is  pushed  forward ;  the  yellow,  supra-spinous,  and  inter-spinous  ligaments  are 
relaxed.  The  lower  articular  processes  glide  downward  upon  the  superior  articular  pro. 
cesses  of  the  vertebra  below.  This  motion  is  not  extensive  ;  it  is  limited  by  the  ante- 
rior common  ligament,  and  the  meeting  of  the  spinous  processes. 

3.  In  the  movements  of  lateral  inclination,  the  discs  are  compressed  on  the  side  to 
which  the  inclination  takes  place,  and  the  central  pulp  is  forced  to  the  other  side.  These 
motions  are  limited,  not  only  by  the  meeting  of  the  transverse  processes,  but  even  be 

*  Tbns  the  uniting  media  of  the  vertebrse  serve  also  as  means  of  Icomotion. 


MECHANISM   OF  THE  VERTEBRAL  COLUMN.  "HSl 

fore  these  touch,  by  the  resistance  of  the  intervertebral  substances,  and  of  the  lateral 
bundles  of  the  anterior  common  ligament. 

4.  Circumduction. — This  motion,  the  centre  of  which  is  in  the  lumbar  region,  appears 
at  first  sight  very  extensive,  because  a  portion  of  the  movement  at  the  hip-joint  is  gen- 
erally ascribed  to  it.  In  reahty,  it  is  very  limited,  and  results  from  a  succession  of  the 
preceding  motions. 

5.  The  movement  of  rotation  is  effected  by  the  twisting  of  the  intervertebral  sub- 
stances. Although  the  motion  of  each  disc  is  very  slight,  yet  the  simultaneous  twisting 
of  them  all  produces  a  general  movement,  by  which  the  anterior  surface  of  the  column 
is  turned  slightly  to  the  sides.  It  is,  however,  upon  the  whole,  very  limited  ;  and  al- 
though in  the  erect  posture  the  trunk  of  the  body  can  describe  a  semicircle,  the  greater 
part  of  this  motion  takes  place  at  the  hip-joint. 

All  the  regions  of  the  vertebral  column  do  not  equally  participate  in  these  general  mo- 
tions. They  are  most  extensive  in  the  cervical  region,  where  we  observe,  1.  Flexion, 
which  may  be  carried  so  far  as  to  make  the  chin  touch  the  upper  part  of  the  sternum ; 
2.  Extension,  so  that  the  neck  may  be  turned  backward  ;  3.  Lateral  inclination,  until  the 
head  nearly  touches  the  shoulder ;  4.  Rotation,  which  is  greater  here  than  in  any  of  the 
other  regions,  notwithstanding  the  presence  of  the  lateral  hook-like  processes  or  ridges.* 
Tliese  motions  may  be  to  such  an  extent  as  to  cause  luxation,  which  can  only  take  place, 
without  fracture,  in  the  cervical  region,  on  accoimt  of  the  ahnost  horizontal  direction  of 
the  articular  processes. 

The  general  movements  are  most  limited  in  the  dorsal  region.  1.  Flexion  is  rendered 
impossible  by  the  presence  of  the  sternum.  The  presence  of  this  bone  in  the  different 
species  of  animals  attests  the  immobility  of  the  dorsal  portion  of  the  column,  in  the  same 
manner  as  its  absence  is  an  indication  of  its  mobility.  2.  Extension  is  prevented  by  the 
meeting  of  the  spinous  processes,  which  are  longer  and  more  closely  imbricated  in  this 
than  in  any  other  of  the  regions.  3.  Lateral  movements  are  rendered  impossible  by  the 
ribs,  which  would  be  forced  against  each  other  if  this  motion  took  place.  4.  As  aU  the 
preceding  motions  are  the  elements  of  circumduction,  it  may  be  easily  conceived  that 
this  can  scarcely  take  place.  5.  The  same  obstacles  oppose  the  movement  of  rotation, 
which  is  also  prevented  by  the  position  of  the  articular  processes,  which  are  directed  ver- 
tically, and  whose  surfaces  on  the  right  and  left  sides  are  not  upon  the  same  plane.  The 
thinness  of  the  intervertebral  substances  in  the  dorsal  region  accords  with  all  these 
arrangements  in  limiting  mobility. 

What  has  been  said  regarding  the  immobility  of  the  dorsal  region  applies  only  to  the 
upper  part  of  this  region.  The  dispositions  at  the  lower  part  are  more  favourable  to  mo- 
bihty.  We  know  that  the  last  two  dorsal  vertebrae  are  remarkable  for  the  shortness  of 
their  spinous  and  transverse  processes ;  and  that  the  ribs  with  which  they  articulate  are 
very  movable,  and  could  not  oppose  the  motions  of  the  vertebras  in  any  degree. 

The  lumbar  region  participates  much  more  in  the  general  motions  than  the  dorsal. 
The  articular  processes  in  this  region  are  much  more  advantageously  adapted  for  rota- 
tion than  in  either  the  dorsal  or  cervical,  for  the  lower  pair  of  each  vertebra  forms  a  solid 
cylinder,  which  is  received  into  the  hollow  surface  of  the  superior  articulating  processes 
of  the  vertebra  below.  This  arrangement  permits  a  motion  resembhng  that  of  the  hinges 
of  a  door. 

It  should  be  remarked,  that  in  all  the  regions  the  lower  articular  processes  of  each 
vertebra  are  placed  behind  the  superior  articular  processes  of  the  succeeding  vertebra, 
ftnd  form  a  sort  of  imbrication.  Each  vertebra,  then,  is  retained  in  its  place  by  a  species 
of  dovetailing,  so  that  it  cannot  be  dislocated  forward  without  breaking  the  superior  ar- 
ticular processes  of  the  vertebra  below,  nor  backward,  without  breaking  the  inferior  ar- 
ticular processes  of  the  vertebra  above.  This  remark  does  not  apply  rigorously  to  the 
cervical  region,  the  articular  processes  of  which  are  oblique,  and  can  permit  dislocation 
■without  fracture. 

Mechanism  of  the  Articulations  of  the  Vertebral  Column  and  the  Head. 
The  movements  of  the  head  upon  the  vertebral  column  are  shared  between  two  artic- 
ulations :  viz.,  1.  The  occipito-atlantal,  to  which  edl  the  motions  of  flexion,  extension, 
lateral  inclination,  and  circumduction  belong ;  2.  The  atlanto-axoid,  which  only  performs 
one  movement,  viz.,  rotation. 

Mechanism  of  the  Occipito-atlantal  Articulation. 
The  movements  of  flexion  and  extension  of  the  head  upon  the  atlas  are  very  limited ; 
when  the  head  is  decidedly  bent  or  inclined,  the  effect  is  produced  by  motion  of  the 
whole  cervical  region.  It  is  possible  to  distinguish  flexion  at  the  occipito-atlantal  artic- 
ulation from  that  which  is  produced  by  the  entire  cervical  region.  In  the  first  case,  the 
chin  approaches  the  vertebral  column,  and  the  skin  on  the  upper  part  of  the  neck  is 

*  We  should  form  an  incorrect  notion  of  the  obstacle  resulting  from  the  lateral  ridges  on  the  bodies  of  tne 
Tcrtebrse,  in  the  pcrfiinnanre  of  rotation,  if  we  were  to  study  them  only  on  the  disarticulated  skeleton.  In  the 
recent  subject  they  scarcely  (ouch  the  vertebra  above,  on  account  of  the  intervertebral  disc. 


124  ARTHROLOGY.  '''''^' 

wrinkled  transversely ;  in  the  latter,  the  spine  bends  at  the  same  time  as  the  head,  con- 
sequently the  interval  between  it  and  the  chin  remains  the  same,  and  there  are  no  trans- 
verse viTinkles  of  the  skin. 

During  flexion  the  condyles  glide  backward  ;  the  odontoid,  the  occipito-axoid,  and  the 
posterior  ligaments  are  stretched,  but  in  extension  the  gliding  takes  place  in  an  oppo- 
site direction. 

The  occipito-atlantal  articulation  is  deprived  of  the  power  of  rotation  by  the  direction 
of  the  condyles,  which  mutually  obstruct  this  movement.  In  birds,  which  have  only  one 
condyle,  the  articulation  of  the  head  admits  of  very  extensive  rotation.  In  the  human 
subject  there  is  a  slight  movement  of  rotation  at  this  joint,  when  the  head  is  previously 
ioclined  upon  one  of  the  condyles,  which  then  serves  as  a  pivot. 

Mechanism  of  the  Atlanto-axoid  Articulation. 

In  the  movements  of  this  articulation,  we  should  regard  the  atlas  and  the  head  as 
forming  only  one  piece.  There  are  no  movements  either  of  flexion  or  extension.  The 
inclusion  of  the  odontoid  process  in  the  syndesmo-atlantal  ring  prevents  even  the  slight- 
est motion  of  the  atlas,  either  forward  or  backward  ;  for  in  the  forward  motion,  or  flex- 
ion, the  atlas  is  fixed  by  the  transverse  ligament,  which  presses  upon  the  odontoid  pro- 
cess ;  and  in  the  backward  motion,  or  extension,  the  atlas  is  fixed  by  its  own  anterior 
arch,  which  is  brought  in  contact  with  the  same  obstacle.  There  is,  moreover,  no  lat- 
eral inclination  at  this  joint,  for  this  is  prevented  by  the  odontoid  ligaments.  Rotation 
is,  therefore,  the  only  movement  which  remains.  In  this  motion,  in  which  the  head  de- 
scribes the  arc  of  a  large  circle  upon  the  vertebral  column,  the  syndesmo-atlantal  ring 
turns  upon  the  axis  as  a  wheel  upon  its  axle.  Of  the  two  plane  surfaces  of  this  joint, 
one  glides  forward,  and  the  other  backward  ;  one  of  the  odontoid  ligaments  is  stretched, 
and  the  other  relaxed.  These  ligaments,  it  should  be  observed,  limit  the  extent  of  rota- 
tion, which  explains  the  necessity  for  their  great  strength ;  but,  great  as  this  is,  their 
resistance  is  occasionally  insufficient,  and  the  odontoid  process  breaking  one  of  them, 
slips  below  the  transverse  ligament,  and  occasions  death  by  compressing  the  spinal  cord, 
Luxation,  therefore,  of  this  articulation  is  to  be  dreaded,  not  merely  for  the  same  rea- 
sons as  other  dislocations,  but  as  being  a  cause  of  compression  of  the  spinal  marrow. 

The  entire  movement  by  which  the  face  is  turned  to  either  side  should  not  be  attrib- 
uted to  this  articulation  alone,  for  it  extends  to  the  fourth  of  a  circle  on  each  side,  and 
such  a  degree  of  motion  would  dislocate  the  articular  surfaces  of  the  atlas  and  the  axis. 

Articulations  of  the  Cranium. 

All  the  bones  of  the  cranium  are  united  together  by  synarthroses.  We  have  here  to 
examine,  as  in  all  other  articulations,  1.  The  articular  surfaces ;  2.  The  means  of  union. 
As  the  bones  of  the  cranium  form  a  complete  cavity,  closed  in  every  direction,  they  unite 
by  their  entire  circumferences  or  by  their  edges  ;  and  as  the  solidity  of  joints  is  in  a  di- 
rect ratio  to  the  extent  of  the  articular  surfaces,  the  bones  of  the  cranium,  which  are 
only  in  contact  by  their  edges,  would  have  been  very  slightly  connected,  had  it  not  been 
for  the  following  provisions  :  1.  The  cranial  bones  are  generally  thicker  at  the  circum- 
ference than  in  the  centre  ;  2.  They  are  almost  all  provided  with  marginal  denticulations 
that  multiply  three  or  four  fold  the  points  of  contact;  3.  The  edges,  instead  of  being  cut 
perpendicularly,  are  bevelled  so  as  to  overlap  each  other,  and  thereby  present  much  more 
extensive  corresponding  surfaces  ;  4.  We  should  observe,  also,  the  number  of  projecting 
and  retreating  angles  that  are  formed  by  these  bones  ;  and,  5.  The  sinuous  arrangement 
of  their  edges,  all  of  which  arrangements  are  most  favourable  to  the  increase  of  solidity. 

We  should  remark,  however,  that  these  different  modes  of  ensuring  solidity  are  not 
employed  indiscriminately  over  the  whole  scull.  In  the  vault  of  the  cranium,  for  exam- 
ple, firmness  is  attained  by  the  mutual  adaptation  of  the  serrated  margins  of  the  bones 
at  the  upper  and  at  the  back  parts,  and  by  their  overlapping  at  the  sides ;  in  the  base,  on 
the  contrary,  the  sohdity  chiefly  depends  upon  the  breadth  of  the  contiguous  surfaces, 
and  upon  the  reception  of  projecting  into  corresponding  retreating  angles.  Examples  of 
this  double  arrangement  may  be  seen  in  the  articulation  of  the  occipital  and  sphenoid 
bones,  which  is  accomplished  by  means  of  broad  surfaces,  and  in  the  articulation  of  the 
projecting  angle  formed  by  the  petrous  portion  of  the  temporal  bone  with  the  retreating 
angle  formed  by  the  occipital  bone  behind  and  the  sphenoid  in  front. 

This  description  will  suffice  to  give  a  general  idea  of  the  mode  of  union  between  the 
bones  of  the  cranium.  It  would  evidently  exceed  the  limits  of  this  work  to  dilate  upon 
the  form  of  each  of  the  sutures,  and  to  follow  Monro  in  distinguishing  fourteen  or  fifteen 
different  kinds.  Nevertheless,  we  do  not  think  a  few  words  regarding  the  principal 
forms  of  the  indentations  will  be  out  of  place.  We  would  therefore  observe,  that  the 
tooth-like  projections  are  sometimes  four  or  five  lines  in  length,  and  are  themselves  in- 
dented on  their  edges,  secondary  denticulations  being  thus  formed.  They  are  generally 
straight,  but  are  sometimes  alternately  bent  towards  the  external  and  the  internal  sur- 
face. Some  of  the  teeth  are,  as  it  were,  pediculated,  and  are  enclosed  between  the  others, 
thus  holding  a  middle  place  between  the  Wormian  bones  and  the  ordinarj'  denticulations 


MECHANISM   OF   THE  CRANIUM.  125 

We  should  remark  that  the  name  suture,  piopurly  speaking,  belongs  more  especially 
to  those  sutures  in  which  the  bones  are  dovetailed ;  that  those  sutures,  the  uniting  sur- 
faces of  which  are  broad  and  oblique,  are  generally  called  squamous ;  and  that  the  sutu 
ra  harmonia  are  those  in  which  the  indentations  are  scarcely  perceptible.  We  must 
also  observe,  1.  With  regard  to  the  sutures,  that  their  indentations  are  much  deeper  on 
the  external  than  on  the  internal  surface  of  the  bones  of  the  cranium ;  2.  With  regard  to 
those  sutures  which  are  bevelled,  that  they  often  present  alternate  oblique  sections,  hav- 
ing opposite  directions,  so  that  of  two  bones,  the  one  that  overlaps  the  other  at  one  part 
of  the  suture  is,  at  another  part,  itself  overlapped :  of  this  we  have  an  example  in  the 
fronto-parietal  suture. 

Means  of  Union  of  the  Bones  of  the  Cranium. 
We  have  remarked,  in  speaking  of  the  development  of  the  bones,  that  those  which 
are  subsequently  united  by  immovable  articulations  are  formed  in  a  piece  of  cartilage 
that  is  common  to  them  all.  Portions  of  this  cartilage,  not  yet  encroached  upon  by  os- 
sification, serve  as  the  uniting  media.  It  is  evident,  therefore,  that  these  cartilages  of 
the  sutures  are  broader  when  the  amount  of  ossification  is  less,  viz.,  in  the  earher  periods 
of  life.  The  pericranium,  on  tlie  outside,  and  the  dura  mater,  on  the  inside,  although 
they  adhere  more  firmly  to  the  bones  along  the  lines  of  the  sutures,  cannot  to  any  con- 
siderable extent  contribute  to  strengthen  the  union  of  the  bones  of  the  cranium. 

Mechanism  of  the  Cranium. 

While  the  vertebral  column  performs  four  offices,  1.  A  cylinder  or  canal  of  protection ; 
3.  A  column  of  support ;  3.  The  central  lever  of  locomotion ;  and,  4.  An  organ  movable 
on  itself  in  its  different  parts,  the  cranium  only  performs  two  :  1.  An  organ  of  locomotion ; 
2.  An  organ  of  protection.  As  an  organ  of  locomotion  we  have  already  fully  studied  it, 
when  examining  the  movements  of  the  vertebral  column,  and,  consequently,  it  only  re- 
mains for  us  to  examine  its  mechanism  as  protecting  the  nervous  mass  which  it  encloses. 

The  cranium  is  nothing  more  than  a  bony  envelope  added  to  the  fibrous  one  which  en- 
closes the  brain,  and  is  exactly  moulded,  on  its  inner  surface,  to  the  external  surface  of 
the  organ  it  encloses.  Before  its  complete  ossification,  the  cranium  may  experience  an 
enlargement  or  diminution  in  size  in  proportion  as  the  organ  it  contains  is  enlarged  or 
diminished  in  volume  ;  but  so  soon  as  its  ossification  has  been  completed,  its  capacity  is 
independent  of  the  volume  of  the  brain.  If  that  organ  is  atrophied,  the  vacancy  is  fiUed 
up  by  serous  fluid ;  if  hypertrophied,  a  fatal  pressure  is  the  consequence.  The  state- 
ments which  have  been  made  by  some,  that  the  capacity  of  the  interior  of  the  cranium 
increases  in  men  of  genius,  and  that  the  head  of  Napoleon  increased  wonderfully  in  size 
during  the  progress  of  his  reign,  we  consider  as  mere  vagaries  of  the  imagination.  As 
the  cranium  encloses  the  brain,  it  is  evident  that  any  motion  between  the  bones  which 
form  this  case  would  be  attended  with  fatal  consequences.  They  are,  therefore,  im- 
movably articulated  to  each  other.  It  might  be  supposed  that  this  solidity  could  have 
been  better  secured,  had  the  brain-case  been  formed  of  one  instead  of  a  number  of  bones. 
But,  independently  of  the  other  important  objects  obtained  by  its  being  made  up  of  a 
number  of  separate  pieces,  its  power  to  resist  fractures  is  increased  by  this  arrangement, 
seeing  that  forces  applied  to  it,  in  being  transmitted  through  its  different  articulations, 
are  weakened,  and  operate  much  less  violently  than  they  would  have  done  without  this 
arrangement. 

What  has  been  said  above  of  the  immobility  of  the  bones  of  the  cranium  is  not  equally 
true  at  all  periods  of  life.  During  foetal  existence,  and  the  first  few  years  after  birth,  the 
intervals  between  the  bones  of  the  cranium  are  occupied  by  a  flexible,  cartilaginous  sub- 
stance, which  permits  those  of  the  roof  to  move  pretty  extensively  upon  each  other. 
Since,  therefore,  the  conditions  of  solidity  are  not  the  same  at  this  period  as  in  the  adult, 
we  must  examine  the  mechanism  of  the  cranium  both  in  the  foetus  and  in  the  adult. 

1.  In  the  foetus,  the  conditions  of  solidity  must  be  studied  both  in  the  roof  and  in  the 
base  of  the  cranium. 

In  the  roof  of  the  cranium,  the  incomplete  ossification  allows  the  bones  to  move  upon 
each  other,  and  in  this  respect  the  encephalon  is  imperfectly  protected.  But,  on  the 
other  hand,  the  presence  of  these  cartilaginous  intervals  diminishes  the  momentum  of  a 
violent  force  applied  to  the  cranium,  and  thus  prevents,  in  some  degree,  both  fractures 
of  the  cranium  and  concussions  of  the  brain.  The  mobility  of  the  bones  is  principally 
displayed  at  birth,  in  their  overlapping,  when  the  head  of  the  foetus  is  passing  through 
the  pelvis.  The  base  of  the  cranium  is  incompressible  at  the  same  period,  and  the  bones 
are  immovable,  because  ossification  has  so  far  advanced  that  they  are  only  separated  by 
very  thin  layers  of  cartilage.  Tliis  arrangement  is  well  adapted  for  the  protection  of  the 
most  important  parts  of  the  encephalon,  which  are  in  the  vicinity  of  the  base  of  the  cranium. 

2.  In  the  adult,  the  roof  and  the  base  of  the  cranium  form  one  piece.  The  roof  being 
most  exposed  to  violence,  we  shall  examine  the  mechanism  of  resistance  in  the  cranium 
to  blows  directed  vertically  upon  the  top  of  the  head ;  and  it  will  be  easy  to  apply  what 
is  said  in  explanation  of  the  effects  of  a  force  so  directed,  to  cases  in  which  violence  is 
applied  in  other  directions. 


tm 


ARTHROLOGY. 


The  effects  which  may  be  presumed  to  follow  a  violent  blow  on  the  top  of  the  scull, 
are,  1.  Concussion  of  its  bony  parietes,  succeeded  by  their  elastic  reaction ;  2.  Disjunc- 
tion of  the  pieces  entering  into  the  formation  of  the  scull ;  and,  3.  Fracture  of  those 
pieces.    We  shall  examine  the  method  in  which  these  results  may  be  produced. 

1.  Concussion  and  Compression  of  the  Cranium  without  Fracture. — The  cranium  may  be 
looked  upon  as  a  hollow  sphere,  endowed  with  a  certain  degree  of  elasticity,  depending 
partly  upon  the  osseous  tissue  itself,  and  partly  upon  the  cartilaginous  laminae  which 
separate  the  bones  ;  and  it  cannot,  therefore,  be  doubted  that,  from  pressure,  or  violent 
blows  on  the  top  of  the  head,  the  scuU  may  undergo  a  flattening,  and  then  recover  its 
original  condition,  like  a  hollow  baU  of  ivory  when  struck  vertically.  The  truth  of  this 
explanation  may  be  shown  at  once  by  projecting  a  scull  against  a  resisting  surface,  when 
it  wiU  be  found  to  rebound  like  an  elastic  ball.  However  sUght  this  flattening  may  be, 
and  the  recovery  which  follows  it,  the  known  laws  of  physics  will  not  aUow  us  to  deny 
its  possibility. 

2.  Tendency  to  Disjunction  of  the  Bones  of  the  Cranium. — This  separation  has  never  been 
observed  as  the  consequence  of  external  blows.  The  following  is  the  manner  in  which 
displacement  is  prevented  in  cases  of  blows  on  the  top  of  the  head.  It  is  evident  that 
violence  applied  in  this  direction  would  have  a  tendency  to  depress  the  upper  edge  of 
the  parietal  bones  ;  but  this  cannot  take  place  without  forcing  the  lower  edge  outward ; 
and  as,  from  the  peculiar  formation  of  the  squamous  suture,  the  parietal  bones  are  over- 
lapped by  the  temporal  and  the  sphenoid,  this  edge  cannot  be  driven  outward  without 
giving  the  temporal  bones  such  a  motion  as  will  tighten  the  articulations  of  the  base  of 
the  cranium.  All  these  articulations  are  remarkable  in  this  respect,  that  the  projecting 
angles  of  some  of  the  bones  are  received  into  the  retiring  angles  of  others.  This  is  ex- 
emplified in  the  articulation  of  the  petrous  portion  of  the  temporal  bone  with  the  sphenoid 
and  the  occipital  bone,  and  in  the  basilar  process  of  the  occipital  bone  with  the  two  tem- 
porals and  the  sphenoid.  The  residt  of  all  these  arrangements  is,  that  blows  upon  the 
top  of  the  head,  instead  of  separating  the  bones  of  the  cranium,  tend  to  render  their  union 
still  closer. 

3.  Another  effect  of  blows  on  the  top  of  the  head  may  be  fracture  of  the  cranial  bones ; 
and  it  will  be  impossible  to  comprehend  the  nature  of  many  of  these  fractures,  without 
a  knowledge  of  the  following  points  of  structure  :  1 .  The  cranium  is  of  unequal  thickness 
in  different  parts.  This  circumstance  explains  how  a  round  body,  striking  the  cranium 
in  a  spot  of  sufficient  strength  to  resist  the  impulse,  may  cause  a  fracture  of  a  more  or 
less  distant  part,  where  the  parietes  are  thinner,  and  consequently  weaker.  It  may  be 
conceived  that  this  kind  of  fracture  may  take  place  either  in  the  bone  struck,  or  in  other 
bones,  and  that  it  may  affect  the  internal  table  only,  the  external  remaining  uninjured. 
2.  The  cranium  is  so  constructed,  that  a  shock  impressed  upon  the  top  is  concentrated  at 
the  base,  being  propagated  on  the  sides  to  the  temporal  bones  and  their  petrous  portions, 
as  well  as  to  the  great  wings  of  the  sphenoid  and  the  body  of  that  bone ;  behind,  by  the 
occipital  bone  to  the  basilar  process  and  the  body  of  the  sphenoid ;  and  in  front,  by  the 
fiontal  bone  and  the  roof  of  the  orbits,  to  the  smaller  wings  and  body  of  the  sphenoid. 
It  will  thus  be  seen  how  blows  upon  various  parts  of  the  scull  may  concentrate  their  ef- 
fects upon  the  base  of  the  cranium ;  and  this  explains  the  production  of  fractures  at  the 
base,  in  consequence  of  violence  inflicted  on  the  roof  of  the  scull.  3.  Most  of  the  cranial 
bones  are  bent  and  angular.  This  disposition,  which  is  observed  at  the  union  of  the  or- 
bital and  frontal  portions  of  the  frontal  bone,  and  at  the  junction  of  the  squamous  and 
petrous  portions  of  the  temporal  bone,  explains  how  these  bones  may  be  broken  by  the 
transmission  of  shocks  from  the  roof  For  we  may  conceive,  when  violence  is  applied 
to  a  bone  which  is  bent  at  an  angle,  that  this  angle  will  be  the  seat  of  a  decomposition 
of  the  force,  one  portion  of  which  is  transmitted  to  the  part  of  the  bone  below  the  angle, 
while  the  remaining  portion  acts  against  the  angle  itself  in  the  original  direction,  and 
may  thus  determine  a  fracture  of  that  part  of  the  bone. 

Although  the  roof  of  the  cranium  is  most  exposed  to  injury,  yet  some  parts  of  the  base 
may  be  reached  by  penetrating  weapons,  as  the  roof  of  the  orbits  and  the  cribriform  plate 
of  the  ethmoid.    It  should  be  remarked,  also,  that  these  are  the  thinnest  parts  of  the  scull. 

Articulations  of  the  Face. 

The  articulations  of  the  face  comprise  those  of  the  upper  and  of  the  lower  jaw. 
Articulations  of  the  Bones  of  the  Superior  Maxilla  with  each  other,  and  with  the  Cranium. 

All  these  articulations  are  sutures,  but  they  have  not  such  large  indentations  as  the 
bones  of  the  cranium ;  almost  all  are  united  by  harmonia  or  juxtaposition.  At  the  same 
time,  it  should  be  remarked  that  a  true  dovetailing  exists  in  these  articulations,  as  may 
be  seen  in  the  junction  of  the  superior  maxillary  bones  (the  fundamental  articulation  of 
the  face),  which  is  effected  by  means  of  thick  furrowed  surfaces,  mutually  and  firmly 
adapted  to  each  other. 

No  suture  in  the  whole  scull  is  stronger  than  that  between  the  malar  and  the  maxil- 
lary bones ;  indented  sutures  are  most  common  on  the  sides  of  the  face.    The  manner 


ARTICULATIONS    OF   THE    FACE.  127 

in  which  the  vertical  portion  of  the  palate  bone  is  received  into  the  furrow  in  the  open- 
ing of  the  maxillary  sinus,  afFords  an  illustration  of  the  suture  by  reception.  There  are 
some  well-marked  indentations  in  the  articulations  of  the  bones  of  the  face  with  those 
of  the  cranium  ;  as  in  the  articulation  of  the  nasal  bones  ;  of  the  ascending  processes  of 
the  superior  maxillae  ;  and  of  the  malar  bones  with  the  frontal ;  in  that  of  the  sphenoid 
with  the  malar  bones  ;  and  of  the  latter  with  the  zygomatic  processes  of  the  temporal 
bones.  Simple  juxtaposition  is  met  with  in  the  junction  of  the  ethmoid  with  the  roof  of 
the  orbit ;  of  the  palate  bone  with  the  pterygoid  processes  ;  and  of  the  vomer  with  the  eth- 
moid ;  but  there  is  a  mutual  reception  in  the  articulation  of  the  vomer  with  the  sphenoid. 
With  regard  to  the  means  of  union,  in  addition  to  the  firm  union  resulting  from  the 
configuration  of  the  articular  surfaces,  there  is  also  a  thin  layer  of  cartilage,  continuous 
with  that  which  formed  the  matrix  of  the  bones,  and  which  is  itself  afterward  obhterated 
during  the  progress  of  ossification. 

Mechanism  of  the  Articulations  of  the  Upper  Jaw. 

As  the  mechanism  of  the  face  is  adapted  both  to  resist  force  applied  from  below  through 
the  medium  of  the  lower  jaw,  and  also  the  effects  of  external  violence,  it  is  necessary  to 
analyze  the  conditions  of  solidity  resulting  from  the  configuration  of  the  upper  jaw ;  and 
in  order  to  appreciate  these  correctly,  we  must  analyze  the  framework  of  the  face. 

The  upper  jaw,  considered  as  a  whole,  forms  inferiorly  a  sort  of  parabola,  circumscri 
bed  by  the  alveolar  border,  which  is  the  strongest  part  of  the  bone,  and  receives  the  di- 
rect impulse  of  the  lower  jaw ;  it  curves  backward,  and  forms  the  roof  of  the  palate, 
which  gradually  diminishes  in  thickness  ;  and,  not  receiving  the  impulse  of  the  lower  jaw 
directly,  its  construction  is  not  so  solid  as  the  alveolar  border.  The  upper  jaw  becomes 
broader  and  flattened  above,  and  separates  into  different  parts  or  prolongations,  which, 
after  enclosing  certain  openings,  unite  with  the  cranium  by  means  of  several  processes, 
that  form,  as  it  were,  so  many  columns  for  resisting  any  impulses  transmitted  from  below. 

These  columns  are,  1.  The  fronto-nasal,  constituted  on  each  side  by  the  ascending  pro- 
cess of  the  superior  maxillary  bone.  These  columns,  which  correspond  to  the  canine 
teeth,  are  remarkably  strong  in  carnivorous  tribes  ;  and  to  their  great  size  may  be  attrib- 
uted the  lateral  position  of  the  orbits  in  these  animals.  The  interval  between  these 
columns  is  occupied  above  by  the  nasal  bones  ;  but  an  opening  is  left  between  them,  be- 
low, shaped  like  a  heart  on  playing  cards.  The  whole  of  that  portion  of  the  alveolar 
edge  situated  beneath  this  opening  is  weaker ;  but  it  should  be  remarked,  that  it  corre- 
sponds to  the  incisor  teeth,  which,  being  adapted  for  cutting,  divide  instead  of  bruising 
or  tearing  the  food,  and  are,  consequently,  not  subject  to  such  powerful  efforts  as  the 
canine  and  molar  teeth. 

2.  The  second  pair  of  columns  is  formed  by  the  malar  eminences,  which  are  contin- 
uous with  the  alveolar  border,  by  the  vertical  ridge  separating  the  canine  from  the  zygo- 
matic fossa.  These  columns,  which  correspond  to  the  second  great  molar  teeth,  may 
be  called  the  zygomato-jugal,  because  they  are  subdivided  into  two  other  secondary  col- 
umns, the  vertical,  malar,  or  jugal,  and  the  horizontal  or  zygomatic.  The  jugal  columns 
are  much  stronger  than  the  fronto-nasal,  and  are  continuous  with  the  external  orbital 
processes  of  the  frontal  bone,  and  with  the  anterior  thick  and  indented  edges  of  the 
great  wings  of  the  sphenoid :  the  second,  or  horizontal,  articulate  with  the  zygomatic 
processes  of  the  temporal  bones,  and  with  them  constitute  the  zygomatic  arches.  From 
this  arrangement,  it  may  be  understood  how  effectually  the  bevelling  of  the  end  of  the 
zygomatic  process  that  rests  upon  the  malar  bone  is  adapted  for  resisting  impulses  com- 
municated from  below.  The  zygomatic  arches,  also,  form  props  that  oppose  all  trans- 
verse displacements.  The  mode  of.  articulation  of  the  zygomatic  processes  with  the 
malar  bones  is  such,  that  the  zygomatic  arches,  although  horizontal,  are  well  C8dculated 
to  resist  any  force  from  below.  In  carnivora,  where  there  are  no  jugal  columns,  the 
zygomatic  arches  are  enormously  large. 

The  fourth  pair  of  columns  are  the  pterygoid,,  intended  to  support  the  face  in  the  antero- 
posterior direction,  being  articulated  with  the  maxillary  bones  through  the  medium  of 
the  palate  bor.es ;  these  also  oppose  any  displacement  upward,  and,  moreover,  serve  to 
support  the  back  part  of  the  alveolar  border. 

There  are,  therefore,  four  pairs  of  columns,  vi».,  Vae  fronto-nasal,  the  jugal,  the  zygo- 
matic arches,  and  the  pterygoid  columns.  They  are  almost  entirely  composed  of  compact 
tissue.  The  principal  columns  are  situated  immediately  above  the  first  great  molares, 
where  the  jugal,  zygomatic,  and  pterygoid  columns  are  concentred,  and  where  the  most 
violent  impulses  are  received.  The  fronto-nasal  columns  correspond  to  the  canine  teeth ; 
their  strength  is  proportioned  to  that  of  these  teeth,  and  hence,  in  carnivorous  animals, 
the  ascending  processes  of  the  superior  maxillae  are  very  large  and  thick.  The  fronto- 
nasal and  jugal  columns  are  near  each  other  below,  and  only  leave  a  small  space  be- 
tween them,  which  is  occupied  by  the  two  small  molares  ;  but  they  are  separated  to  a 
considerable  distance  above,  and  enclose  the  orbital  fossae. 

In  this  manner  the  deep  fossae  in  the  face  are  formed  without  being  prejudicial  to  its 
strength.     Even  the  maxillary  sinus  does  not  much  diminish  the  solidity  of  the  face. 


128  ARTHROLOGY. 

because  it  is  situated  in  the  interval  between  the  columns,  and  because  only  a  small 
portion  of  it  corresponds  to  the  alveolar  border. 

These  details  wiU  suffice  to  show  that  the  upper  jaw  has  been  framed  to  resist  ex- 
ternal impulses,  but  especially  forces  communicated  from  below  by  the  lower  jaw  ;  that 
the  alveolar  border,  being  intended  to  receive  the  impulse  directly,  is  most  strongly  con- 
structed ;  that  the  whole  force  applied  to  the  upper  jaw  is  transmitted  by  the  fronto-nasal 
columns  to  the  internal  orbital  processes,  by  the  malar  columns,  partly  to  the  external 
orbital  processes,  and  partly  to  tlie  zygomatic  arches,  and  by  the  palate  bone  to  the  ptery- 
goid columns  of  the  sphenaid  ;  that  the  vomer  transmits  little  or  nothing  either  to  the 
ethmoid  or  the  sphenoid ;  and  that  the  cranium,  on  its  part,  opposes  very  imyielding 
structures  to  the  sustaining  pillars  of  the  face.  To  forces  directed  from  before  back- 
ward, the  zygomatic  arches  and  the  pterygoid  processes  offer  great  resistance  ;  against 
lateral  violence  each  malar  bone  resists  like  an  arch,  and  transmits  the  impulse  it  has 
received  to  the  superior  maxillary  bone,  the  frontal  and  the  sphenoid.  \  The  greatest 
part  of  the  impulses  communicated  to  the  face  are  then  ultimately  tranbtiitted  to  the 
cranium ;  and  were  it  not  for  the  multiplicity  of  its  constituent  parts,  and  the  great  num- 
ber of  articulations  which  absort)  part  of  the  force,  the  brain  contained  within  it  would 
be  frequently  exposed  to  dangerous  violence.  The  upper  jaw  is  concerned  in  the  pro- 
cess of  mastication  merely  as  a  means  of  support ;  for  though  it  may  be  raised  when  the 
mouth  is  opened,  and  depressed  when  the  mouth  is  shut,  these  movements  belong  to 
the  entire  head,  and  result  from  the  action  of  its  extensor  muscles,  which  thus  become 
powerful  auxiliaries  of  mastication  in  the  carnivorous  animals. 

Temporo-maxillary  Articulation  (figs.  65,  66,  and  67). 
This  joint,  the  centre  of  all  the  movements  of  the  lower  jaw,  is  a  double  condyloid  ar- 
ticulation. The  articular  surfaces  are,  1.  The  two  condyles  of  the  lower  jaw,  transverse- 
ly oblong,  and  directed  somewhat  obliquely  inward  and  backward,  so  that  their  axis,  if 
prolonged,  would  intersect  behind  :  2.  The  glenoid  cavity  of  each  temporal  bone,  and  the 
transverse  root  of  its  zygomatic  process.  These  surfaces  are  covered  with  cartilage. 
The  glenoid  cavity  is  remarkable  both  for  its  depth  and  its  capacity.  Its  depth  is  in- 
creased by  several  eminences  on  its  borders :  viz.,  on  the  inside,  by  the  spine  of  the 
sphenoid  ;  and  behind,  by  the  styloid  and  the  vaginal  processes,  the  latter  of  which  is 
nothing  more  than  the  anterior  lamina  of  the  auditory  meatus.  The  capacity  of  the 
glenoid  cavity  is  no  less  remarkable,  being  double  or  triple  that  which  would  be  neces- 
sary to  receive  the  condyle  ;  moreover,  the  whole  of  this  cavity  is  not  articular,  the  part 
situated  behind  the  glenoidal  fissure  being  extraneous  to  the  joint.  This  disproportion 
between  thp  cavity  and  the  condyle  is  only  observed  in  man  and  in  ruminantia :  in  ro- 
dentia  and  carnivora,  the  one  is  exactly  proportioned  to  the  other.  The  portion  of  the 
glenoid  cavity  posterior  to  the  fissure  affords  an  example  of  those  supplementary  cavities 
that,  in  certain  circumstances,  increase  or  replace  the  principal  cavity.  All  that  part  of 
the  glenoid  cavity  situated  anteriorly  to  the  fissure  belongs  to  the  joint,  and  is,  there- 
fore, covered  with  cartilage.* 

The  transverse  root  of  the  zygoma,  convex  from  before  backward,  and  concave  trans- 
versely, is  also  articular,  and  covered  by  a  cartilage,  which  is  a  continuation  of  that  lining 
the  glenoid  cavity.  This  articulation  presents  the  only  example  in  the  body  of  two  con- 
vex surfaces  moving  upon  each  other. 

The  means  by  which  motion  is  facilitated  and  union  maintained  in  this  articulation 
are  an  inter-articular  cartilage,  an  external  lateral  ligament,  and  two  synovial  mem- 
branes ;  the  internal  lateral  ligament  of  some  authors,  and  the  stylo-maxillary  ligament, 
do  not  belong  to  this  joint. 

1.  Inter-articular  Cartilage  {a,  fig.  65). — This  cartilage  is  interposed  between  the  artic- 
Pig,  65.  ular  surfaces  ;  it  is  thick  at  the  circumference,  and  some- 

times perforated  at  the  centre,  and  resembles  a  bi-con- 
cave  lens,  with  this  peculiarity,  that  its  upper  surface 
is  alternately  convex  and  concave,  to  correspond  with 
the  glenoid  cavity  and  the  transverse  root  of  the  zygoma ; 
while  the  lower  surface  is  concave,  and  adapted  to  the 
condyle.  Its  circumference  is  free,  excepting  on  the  out- 
side, whfere  it  adheres  to  the  external  lateral  ligament, 
and  on  the  inside,  where  it  gives  attachment  to  some 
fibres  of  the  external  pterygoid  muscle.  This  circum- 
stance is  of  great  importance  in  regard  to  the  mechanism 
of  the  joint.  The  existence  of  an  inter-articular  cartilage  in  a  joint  which  is  subjected 
to  such  considerable  pressure,  and  is  so  often  put  in  motion,  agrees  with  the  general 
law  already  pointed  out.     (Vide  The  Akticulations  in  general). 

*  The  study  of  the  condyle  and  the  glenoid  cavity  is  of  very  great  importance  in  comparative  anatomy  ;  for 
by  the  characters  which  they  present,  we  may  easily  recognise  the  head  of  one  of  the  rodentia,  carnivora,  or 
ruminantia.  1.  In  carnivora,  the  condyles  are  transversely  oblong,  the  long  axes  of  both  being  in  the  same 
line  ;  they  are  received  into  very  deep  cavities.  2.  In  rodentia,  on  the  contrary,  the  long  ditinietiy  of  the  con- 
dyles is  directed  from  before  backward.  3.  In  ruminantia,  the  glenoid  cavity  is  flat,  as  well  as  the  head  of 
the  condyle,  while  the  transverse  root  of  the  zygoma  is  scarcely  discernible. 


ARTICULATIONS   OF    THE    FACE. 


129 


Fig.  66. 


2.  External  Lateral  Ligament  (J,  fig.  66). — This  ligament  extends  from  the  tubercle  sit- 
uated at  the  junction  of  the  two  roots  of  the  zygoma  to 
the  outside  of  the  neck  of  the  condyle  :  it  is  directed 
obliquely  downward  and  backward,  and  forms  a  thick 
band  covering  the  whole  of  the  outside  of  the  articu- 
lation :  it  is  in  contact  with  the  skin  externally,  and  in- 
ternally with  the  two  synovial  capsules,  and  the  inter- 
articular  cartilage. 

Anatomists  have  described,  under  the  name  of  the 
internal  lateral  or  spheno-maxillary  ligament  (c,  fig.  67), 
an  aponeurotic  band,  which,  neither  as  regards  its  po- 
sition or  its  use,  can  be  considered  as  properly  belong- 
ing to  the  joint ;  it  is  extended  from  the  spinous  process  of  the  sphenoid  to  the  spine  sit- 
uated on  the  inside  of  the  orifice  of  the  inferior  dent2il  canal.  It  is  a  very  thin  band, 
which  covers  the  inferior  dental  vessels  and  nerves,  and  pig^  67. 

separates  them  from  the  pterygoid  muscles.  Since  the  band 
just  described  has  no  effect  in  giving  strength  to  the  joint, 

it  may  be  wondered  that  there  is  only  one  ligament  for  the  ^g^^  TMHilllBUmK 

articulation  ;  but  it  should  be  observed  that,  as  the  lower  ^*  VrnWiillilfri 

jaw  is  articulated  in  the  same  manner  at  both  its  extrem- 
ities, the  external  lateral  ligament  of  the  one  exactly  per- 
forms the  functions  of  an  internal  lateral  ligament  to  the 
other. 

The  stylo-maxillary  ligament  (d,  figs.  65,  66,  and  67)  ap- 
pears to  me  to  hold  the  same  place  as  the  preceding ;  it  is  a  fibrous  band  extending  from 
the  styloid  process  to  the  angle  of  the  inferior  maxUla.  It  has  no  relation  to  the  union  of 
the  articular  surfaces.  Its  use  appears  to  be  that  of  giving  attachment  to  the  stylo- 
glossus muscle.    Meckel  calls  it  the  stylo-mylo-hyoid  ligament. 

3.  There  are  two  synovial  capsules  in  this  joint,  one  on  the  upper  and  the  other  on 
the  lower  surface  of  the  inter-articular  cartilage  (see  fig.  65).  Sometimes  they  commu- 
nicate by  an  opening  in  the  cartilage  ;  the  superior  is  looser  than  the  inferior ;  and  thus 
the  articular  cartilage  is  more  closely  united  to  the  condyle  of  the  lower  jaw  than  to  the 
glenoid  cavity. 

These  two  synovial  capsules  are  in  contact  on  the  outside  with  the  external  lateral 
ligament,  and  elsewhere  with  a  thin  layer  of  fibrous  tissue. 

Mechanism  of  the  Temporo-maxillary  Articulation. 

In  considering  the  action  of  this  joint,  the  lower  maxilla  may  be  regarded  as  a  ham- 
mer which  strikes  against  the  anvil  represented  by  the  upper  jaw ;  it  is  a  double  angu- 
lar lever,  the  axis  of  its  motion  being  represented  by  a  horizontal  line  that  would  pass 
through  the  middle  of  the  rami.  This  articulation,  which  belongs  to  the  class  of  condy- 
loid joints,  has  been  ranged  among  the  angular  ginglymi,  on  account  of  the  great  extent 
of  its  movements  in  two  opposite  directions,  during  its  elevation  and  its  depression ;  but 
it  differs  from  them  in  being  so  constructed  as  to  admit  of  slight  lateral  movements.  It 
can  also  be  moved  forward  and  backward. 

1.  Depression. — In  this  movement  each  condyle  rolls  forward  in  its  glenoid  cavity,  and 
then  passes  upon  the  transverse  root  of  the  zygoma,  with  a  sudden  jerk,  which  may  be 
easily  felt  by  placing  the  finger  on  the  condyle  while  the  mouth  is  being  opened ;  at  the 
same  time  the  angle  of  the  jaw  is  moved  backward.  The  condyle  carries  with  it  the 
inter-articular  cartilage  ;  for  the  union  of  these  two  parts  is  of  such  a  nature  that,  even 
in  dislocation  of  the  jaw,  they  are  never  separated.  This  depends  not  only  upon  the 
comparative  tightness  of  the  lower  synovial  capsule,  but  also  on  the  mode  of  insertion 
of  the  external  pterygoid  muscle,  which,  being  attached  both  to  the  neck  of  the  condyle 
and  the  inter-articular  cartilage,  acts  simultaneously  upon  them.  The  other  parts  of  the 
joint  are  affected  in  the  following  manner  :  During  depression  of  the  lower  jaw,  the  ex- 
ternal lateral  ligament  is  stretched  ;  the  upper  synovial  capsule  is  distended  behind,  but 
readily  yields  on  account  of  its  laxity.  The  spheno-maxillary  band,  or  internal  lateral 
ligament,  which  is  inserted  at  an  almost  equal  distance  from  the  condyle,  which  is  car- 
ried forward,  and  from  the  angle  of  the  jaw,  which  is  carried  backward,  remains  unal- 
tered, being  neither  stretched  ner  relaxed. 

When  the  depression  is  carried  too  far,  either  from  the  effect  of  a  blow  upon  the  bone, 
or  during  a  convulsive  yawn,  the  condyle  is  dislocated  into  the  zygomatic  fossa;,  tearing 
the  superior  synovial  capsule,  and  carrying  with  it  the  inter-articular  cartilage.*  Thi^ 
mode  of  displacement  is  impossible  in  the  infant ;  for,  from  the  obliquity  of  the  ascend- 
ing ramus  of  tlie  jaw,  the  upper  part  of  the  condyle  looks  backward,  and,  in  order  to  be 


*  This  luxalion-would  be  much  more  common  were  it  not  for  the  inter-articular  cartilage,  which,  by  al- 
ways iiiri.mpji.  ying  the  condyle,  presents  a  smooth  surface,  oTer  which  the  latter  may  glide  in  returning^  into 

R 


130  ARTHROLOGY. 

luxated  forward,  would  have  to  traverse  a  much  larger  space  than  it  does  even  when 
the  mouth  is  opened  to  the  greatest  possible  extent. 

2.  In  elevation,  the  condyle  rolls  backward,  upon  the  transverse  process,  into  the  gle- 
noid cavity.  The  external  lateral  ligament  is  relaxed.  The  obstacles  to  too  great  an 
elevation  are,  1.  The  meeting  of  the  dental  arches.  2.  The  presence  of  the  vaginal 
process  and  the  anterior  wall  of  the  auditory  meatus  ;  and  it  is  very  probable  that  the 
extensive  movements  of  the  jaw  in  the  old  subject,  when  the  teeth  are  lost,  are  permit- 
ted by  the  size  of  the  glenoid  cavities.  Without  that  portion  of  the  glenoid  cavity  which 
is  behind  the  fissure  of  Glasserus,  the  toothless  alveolar  edges  of  the  aged  could  never 
be  brought  in  contact. 

The  forward  motion  is  not,  like  the  preceding,  the  motion  of  a  lever  in  which  the  jaw 
turns  upon  its  axis  ;  it  is  a  horizontal  movement,  in  which  the  condyle  is  brought  under 
the  transverse  root  of  the  zygoma.  A  preliminary  and  indispensable  condition  to  this 
movement  is  a  slight  depression  of  the  whole  of  the  lower  maxilla.  In  this  movement 
all  the  ligaments  are  stretched ;  if  it  were  carried  too  far,  the  coronoid  process  would 
strike  against  the  bone  in  the  zygomatic  fossa,  and  this  circumstance  would  prevent  the 
possibility  of  luxation  of  the  condyle. 

The  backward  motion  requires  no  special  remark. 

The  lateral  movements  differ  from  the  preceding  in  the  mechanism  by  which  they  are 
effected.  In  the  first  place,  the  whole  bone  does  not  move  from  its  place.  One  of  the 
condyles  alone  escapes  from  its  socket,  while  the  other  remains  in  the  glenoid  cavity. 
The  bone,  therefore,  turns  upon  one  of  the  condyles  as  on  a  pivot. 

The  external  lateral  ligament  of  that  articulation  in  which  the  condyle  moves  is  much 
stretched. 

The  lateral  motions  would  have  been  much  more  extensive  had  not  the  two  condyles 
mutually  obstructed  each  other  in  all  movements  but  that  of  depression,  by  reason  of 
their  opposite  directions.  This  may  be  shown  by  sawing  a  maxilla  through  the  middle, 
and  moving  each  of  the  halves.  Moreover,  the  styloid  and  vaginal  processes,  and  the 
spine  of  the  sphenoid,  prevent  displacement  inward. 

Articulations  of  the  Thorax. 

The  articulations  of  the  thorax  comprehend,  1.  The  costo-verteDral  articulations ;  2. 
The  chondro-sternal ;  3.  The  articulations  of  the  cartilages  of  the  ribs  with  each  other ; 
4.  The  junction  of  the  cartilages  and  the  ribs. 

The  Costo-vcrtebral  Articulations  {figs.  58  to  60,  and  68). 

Preparation. — Saw  the  ribs  across  at  their  posterior  angles.  Remove  with  care  the 
pleura  and  the  subjacent  cellular  tissue  in  front,  and  the  muscles  of  the  vertebral  grooves 
behind.  After  having  studied  the  superficial  ligaments,  expose,  1.  The  costo-transverse 
interosseous  ligament  by  a  horizontal  section  of  the  rib,  and  the  transverse  process  to 
which  it  is  attached ;  2.  The  costo-vertebral  interosseous  ligament  by  a  similar  horizon- 
tal section,  including  one  vertebra  and  one  rib,  and  passing  above  the  angular  part  of  the 
joint.  This  last  ligament  may  be  also  exposed  by  a  vertical  section  of  the  rib  and  the 
two  vertebrae  with  which  it  is  connected.  The  costo-vertebral  articulations  have  some 
characters  which  are  common  to  them  all,  and  others  that  are  peculiar  to  a  few. 

General  Characters  of  the  Costo-vertebral  Articulations. 

Articular  Surfaces. — In  this  joint,  the  head  of  the  rib  is  applied  to  the  angular  surface 
formed  by  the  two  half  facettes  (//,  fig.  58)  upon  the  sides  of  the  bodies  of  the  dorsal 
vertebraj,  so  that  each  rib  is  articulated  with  two  vertebrae  {costo-vertebral  articulation, 
properly  so  called) ;  and,  in  addition,  the  tubercle  of  the  rib  is  applied  to  the  facette  {g,figs. 
58,  60,  and  68)  on  the  fore  part  of  the  transverse  process  {costo-transverse  articulation). 

With  regard  to  the  costo-vertebral  articulation,  it  is  to  be  remarked,  1 .  That  it  affords 
an  example  of  a  projecting  angular  facette  received  into  a  retreating  angular  facette, 
which  has  giver,  rise  to  the  mistaken  notion  that  this  joint  is  an  angular  ginglymus  ;  and, 
2.  That  in  each  articulation  the  lower  hcdf  facette  is  twice  as  large  as  the  upper. 

The  surfaces  of  the  costo-transverse  articulation  are,  a  convex  facette  belonging  to  the 
tubercle  of  the  rib,  and  a  concave  one  belonging  to  the  tranverse  process.  Sabatier  af- 
firms that  the  articular  surfaces  of  the  transverse  processes  look  forward  and  upward  in 
the  upper  vertebrae,  and  forward  and  downward  in  the  lower,  and  directly  forward  in 
those  which  occupy  the  middle  of  the  column.  This  arrangement  has  been  referred  to 
in  explanation  of  the  mechanism  of  the  dilatation  of  the  thorax,  by  depression  of  the  low- 
er, and  elevation  of  the  upper  ribs  ;  but  this  explanation  is  unfounded. 

In  addition  to  the  costo-vertebral  and  costo-tran verse  articulations,  the  neck  of  the  rib 
{c,fig.  68),  without  being  in  immediate  contact  with  the  tranverse  process,  is,  in  some 
degree,  united  with  it  by  symphysis. 

Means  of  Union. — These  joints  are  examples  both  of  symphysis  and  arthrodia.  Some 
of  the  ligaments  are  external  to  the  articulation,  the  remainder  are  interosseous. 

The  ligaments  external  to  the  articulation  are,  the  anterior  costo-vertebral  or  stellate  lig- 


ARTICULATIONS   OF    THE    THORAX.  131 

ament,  the  superior  and  the  inferior  ligsiments,  the  posterior  costo-transverse,  and  the 
superior  costo-transverse. 

1.  The  anterior  costo-vertebral,  or  stellate  ligament  {I,  fig.  58),  arises  from  the  two  verte- 
brae with  which  the  rib  is  connected,  and  from  the  corresponding  intervertebral  substance. 
From  these  points  its  fibres  converge,  and  are  inserted  in  front  of  the  extremity  of  the  rib. 

2  and  3.  Besides  the  stellate  ligament  there  are  two  small  ligamentous  bundles,  a  su- 
perior and  an  inferior,  which  extend  from  each  of  the  vertebrae,  concurring  to  form  the 
articulation,  to  the  extremity  of  the  rib. 

4.  The  posterior  costo-transverse  ligament  {m,fig.  59  :  transverse  ligament  of  Boyer,  poste- 
rior costo-transverse  ligament  of  Bichat)  is  a  fibrous  band  stretched  from  the  apex  of  the 
transverse  process,  in  an  oblique  direction,  to  the  non-articular  portion  of  the  tubercle  of 
the  rib. 

5.  The  superior  costo-transverse  ligament  (n,  figs.  58,  59  :  costo-transverse  of  Boyer,  infe- 
rior costo-transverse  of  Bichat)  consists  of  a  band,  which  arises  from  the  lower  edge  of 
each  transverse  process,  passes  obhquely,  and  is  inserted,  not  into  the  rib,  which  articu- 
lates with  that  process,  but  into  the  upper  edge  of  the  neck  of  the  rib  below.  At  the 
place  of  this  insertion,  we  always  find  a  crest  or  spine.  This  ligament  is  sometimes  di- 
vided into  two  or  three  bundles  ;  it  forms  the  continuation  of  a  thin  aponeurosis,  which 
covers  the  external  intercostal  muscle,  and  completes  the  externjd  wall  of  the  opening 
through  which  the  posterior  branches  of  the  intercostal  vessels  and  nerves  are  transmit- 
ted. This  ligament  is  interposed  between  the  anterior  and  posterior  branches  of  these 
vessels  and  nerves. 

The  interosseous  ligaments  are  two  in  number.  1.  A  costo-vertebral  interosseous  ;  2. 
A  costo-transverse  interosseous. 

1.  The  costo-vertebral  interosseous  ligamervt  (o,fig.  58)  is  a  small  bundle  of  fibres,  very 
short  and  very  thin,  extending  horizontally  from  the  projecting  angle  on  the  head  of  the 
rib  to  the  retreating  angle  of  the  vertebral  facette,  where  it  is  continuous  with  the  inter- 
vertebral substance. 

2.  The  costo-transverse  interosseous  ligament  (a,  fig.  68)  is  formed  by  some  ligamentous 
bundles  intermixed  with  reddish  adipose  tissue,  which  stretch  jYg-.  68. 
from  the  anterior  surface  of  the  transverse  process  to  the  pos- 
terior surface  of  the  neck  of  the  rib.  An  idea  of  the  strength 
of  this  ligament  may  be  formed  by  attempting  to  separate  the 
rib  from  the  transverse  process,  after  the  anterior  costo-ver- 
tebral and  the  posterior  costo-transverse  ligaments  have  been 
divided. 

There  are  three  synovial  capsules  in  the  articulations  of  the 
ribs  with  the  vertebrae  :  one  between  the  tuberosity  and  the 
transverse  process,  and  two  small  ones  for  the  two  surfaces  which  are  separated  by  the 
costo-vertebral  interosseous  ligament. 

Characters  peculiar  to  certain  Costo-vertebral  Articulations. 

The  articulations  of  the  first,  eleventh,  and  twelfth  ribs  alone  present  peculiarities. 

1.  Costo-vertebral  Articulation  of  the  First  Rib. — The  rounded  head  of  the  first  rib  is  re- 
ceived into  a  cavity  on  the  side  of  the  body  of  the  first  dorsal  vertebra ;  the  articulation 
is,  therefore,  a  species  of  enarthrosis ;  there  is  neither  a  costo-vertebral  interosseous  lig- 
ament, nor  a  superior  costo-transverse  ligament ;  the  synovial  membrane  is  much  looser 
than  in  the  corresponding  articulations. 

2.  The  costo-vertebral  articulations  of  the  eleventh  and  twelfth  ribs  present  the  same  char- 
acters as  the  preceding  in  this  respect,  that  the  articular  cavity  for  the  head  of  the  bone 
is  situated  upon  one  vertebra  alone.  The  head  of  the  rib  is  flattened,  or  very  slightly 
convex,  and  there  is  no  interosseous  costo-vertebral  ligament.  The  superior  costo-trans- 
verse ligament  is  much  broader  and  stronger  than  in  the  other  articulations.  As  the 
eleventh  and  twelfth  ribs  have  no  tuberosities,  and  the  transverse  processes  of  the  cor- 
responding vertebrse  are  but  little  developed,*  it  follows  that  there  is  no  costo-transverse 
articulation  ;  but  yet  there  is  a  costo-transverse  interosseous  ligament.  All  these  liga- 
ments are  much  more  loose  than  in  the  other  articulations. 

Tlie  Chondro-sternal  Articulations  (Jig.  69). 

There  are  §even  in  number  on  each  side,  formed  by  the  internal  angular  end  of  the 
cartilages,  which  are  received  into  the  angular  cavities  on  the  side  of  the  sternum.  The 
means  of  union  are,  1.  A  radiated  or  anterior  chondro-sternal  ligament  {a,  fig.  69),  which  is 
tolerably  strong  :  it  crosses  in  the  median  line  with  the  corresponding  ligament  of  the 
opposite  side,  and  is  blended  both  with  the  periosteum  and  the  aponeurotic  insertions  of 
the  greater  pectoral  muscles,  in  the  thick  fibrous  layer  which  covers  the  sternum ;  2. 
Two  small  ligaments,  a  superior  and  an  inferior ;  3.  A  radiated  or  posterior  chondro-sternal 
ligament,  much  weaker  than  the  anterior.     The  existence  of  a  synovial  membrane  is 

*  Sometimes,  however,  the  transverse  process  of  the  eleventh  dorsal  vertebra  is  enlarged,  and  articulated 
to  the  eleventh  rib. 


132  ARTHEOLOGY. 

merely  inferred  from  analogy,  for  it  cannot  be  demonstrated.     {Vide  Articulations  in 

GBNERAL.) 

The  first,  second,  sixth,  and  seventh  chondro-stemal  articulations  present  some  pe- 
culiarities. 1.  The  cartilage  of  the  first  rib  is  sometimes  continuous  with  the  sternum, 
and  is  sometimes  articulated  like  the  cartilages  of  the  other  ribs.  I  found  in  one  sub- 
ject the  first  rib  excessively  movable,  because  its  cartilage,  instead  of  being  continuous 
with  the  sternum,  had  its  upper  edge  applied  to  the  side  of  that  bone  to  which  it  was 
united  by  ligaments,  and  was  ultimately  articulated  by  a  narrow  extremity  immediately 
above  the  second  rib.  2.  The  second  cartilage  (ft)  is  much  more  angular  at  its  inner  ex- 
tremity than  any  of  the  others ;  it  is  received  into  the  retreating  angle  formed  by  the 
union  of  the  first  two  pieces  of  the  sternum.  Sometimes  there  is  an  interosseous  liga- 
ment in  this  joint,  running  from  the  angle  of  the  cartilage  to  the  bottom  of  the  cavity, 
and  there  are  then  two  synovial  capsules  :  in  other  cases  there  is  only  one  (c),  but  it  is 
always  more  marked  than  in  the  other  joints.  3.  The  articulations  of  the  sixth  and  sev- 
enth cartilages,  besides  the  anterior  ligaments,  have  also  a  chondro-xiphoid  ligament  more 
or  less  strong,  which  crosses  with  the  ligament  of  the  opposite  side  in  front  of  the  ensi- 
form  cartilage  and  the  lower  end  of  the  sternum.  Sometimes  this  ligament  only  exists 
for  the  seventh  cartilage  ;  it  is  intended  not  only  to  strengthen  the  chondro-stemal  ar- 
ticulations, but  also  to  maintain  the  xiphoid  appendix  in  its  place. 

The  Chondro-costal  Articulations. 

The  cartilages  are  immovably  united  to  the  ribs  ;  the  anterior  extremity  of  the  rib  is 
hollowed  to  receive  the  external  end  of  the  cartilage  :  there  is  no  ligament.  The  perios- 
teum is  the  only  bond  of  union  between  the  costal  cartilage  and  the  rib,  as  in  the  articu- 
lations of  the  cranial  bones. 

The  Artiadations  of  the  Costal  Cartilages. 

The  first,  second,  third,  fourth,  and  fifth  costal  cartilages  do  not  articulate  together, 
unless  the  aponeurotic  laminae,  sometimes  very  strong,  which  form  the  continuation  of 
the  external  intercostal  muscles,  and  occupy  the  whole  length  of  the  cartilages,  be  con- 
sidered as  uniting  media. 

The  sixth,  seventh,  and  eighth  cartilages,  frequently  the  fifth,  and  sometimes  the  ninth, 
present  true  articulations.  Some  cartilaginous  processes  arise  from  the  neighbouring 
edges,  and  come  in  contact  with  each  other  :  there  are  sometimes  two  articular  facettes 
between  the  sixth  and  the  seventh  cartilages.  The  means  of  union  are  some  vertical 
fibres  united  in  bundles  so  as  to  form  two  ligaments,  the  one  anterior  and  thicker,  the 
other  posterior  and  thinner.  There  is  a  much  more  distinct  synovial  membrane  than  in 
the  chondro-stemal  articulations.  The  seventh,  eighth,  and  tenth  cartilages  have  not 
always  articular  facettes,  but  are  simply  united  by  vertical  ligaments. 

Mechanism  of  the  Thorax. 
As  the  thorax  performs  the  double  oflice  of  protecting  the  organs  which  it  encloses,  and 
el  assisting  by  its  movements  in  the  function  of  respiration,  we  must  consider  its  mecha- 
nism with  reference  to  both  these  ends. 

Mechanism  of  the  Thorax  for  the  Protection  of  the  contained  Organs. 

1.  The  following  is  the  mechanism  by  which  the  thorax  is  enabled  to  resist  pressure 
or  violent  blows  directed  from  before  backward.  The  sternum  is  supported  by  the  four- 
teen ribs,  which,  like  buttresses,  oppose  their  united  strength  to  any  causes  of  displace- 
ment or  fracture  ;  it  is  therefore  very  rare  to  find  the  sternum  driven  backward,  and  all 
the  ribs  broken,  however  great  the  violence  may  have  been.  The  elasticity  of  the  car- 
tilages and  of  the  ribs,  and  the  number  of  articulations  which  exist  in  the  thorax,  are  all 
circumstances  most  favourable  to  strength,  because  they  diminish  the  intensity  of  exter- 
nal blows  by  neutralizing  a  certain  amount  of  impulse  :  yet  I  have  met  with  one  case  in 
which  all  the  sternal  ribs  were  broken  by  a  fall,  as  completely  as  if  the  anterior  wall  of 
the  thorax  had  been  divided  for  an  anatomical  preparation.  I  should  remark,  also,  that 
the  flexibility  of  the  ribs  and  their  cartilages  permits  great  depression  of  the  sternum 
without  fracture  ;  and  this  explains  the  possibility  of  contusion,  and  even  rapture  of  the 
heart,  lungs,  or  great  vessels,  without  fracture  of  the  bones  of  the  thorax.  The  degree 
of  resistance  of  the  anterior  wall  of  the  thorax  may  be  also  considerably  varied  by  the 
state  of  relaxation  or  contraction  of  the  muscles,  which  should  be  considered  as  active 
and  contractile  supports  to  the  arch,  of  which  the  stemum  forms  the  key-stone. 

2.  In  the  case  of  lateral  pressure  or  blows,  the  thorax  resists,  like  an  arch,  the  vault 
of  which  is  represented  by  the  convexity  of  the  twelve  ribs,  and  its  pillars  by  the  ster- 
num in  front  and  the  vertebrae  behind.  External  violence  cannot  act  upon  the  whole 
side  of  the  chest  at  once,  as  it  does  upon  the  front,  and  therefore  the  ribs  ofltr  a  more 
partial  resistance  laterally,  and  are  accordingly  much  more  easily  broken  by  direct  blows 
In  this  case,  also,  as  in  the  former,  when  the  elevator  muscles  of  the  ribs  are  in  action, 
the  resistance  is  considerably  increased  ;  and  individuals  have  been  then  able  to  beai 


ARTICULATIONS   OF   THE    RIBS.  133 

giiorttious  •WTei^ts,  which  would,  in  all  probability,  have  fractured  the  ribs,  had  the  raus> 
cles  been  relaxed. 

What  has  been  said  above  of  the  manner  in  which  the  ribs  withstand  violence  is  not 
however,  applicable  to  the  false  ribs,  which,  having  no  fixed  point  on  the  stemui.l  are 
depressed  into  the  abdominal  cavity. 

Mechanism  of  the  Thorax  with  reference  to  Mobility. 

The  thorax  is  not  equally  movable  throughout.  The  middle  portion,  which  corresponds 
to  the  heart,  and  which  is  formed  by  the  sternum  and  vertebral  column,  has  a  very  limit- 
ed degree  of  mobility,  vvhile  the  sides  which  correspond  to  the  lungs  are  endowed  with 
the  power  of  extensive  motion. 

The  movements  of  the  thorax  consist  of  alternate  dilatations  and  contractions,  from 
which  its  mechanism  has  been  compared  to  that  of  a  pair  of  bellows.  They  result  from 
the  motions  which  take  place  at  the  costo-vertebral  and  chondro-sternal  articulations, 
and  at  the  articulations  of  the  cartilages  with  each  other.  We  cannot  explain  the  move- 
ments of  each  rib,  and  of  the  entire  thorcix,  without  first  analyzing  the  motions  at  each 
of  the  above  joints. 

Movements  of  the  Costo-vertebral  Articulations. 

These  articulations  permit  only  very  limited  gliding  motions.  In  these  movements, 
each  rib  represents  a  lever,  which  moves  upon  the  fulcrum  afforded  by  the  vertebral  col- 
umn. It  may  describe  the  movements,  1.  Of  elevation;  2.  Of  depression  ;  3.  It  may  be 
carried  inward ;  4.  It  may  be  carried  outward ;  5.  It  may  perform  a  revolving  motion 
around  the  cord  of  the  arc  which  it  represents.  These  different  movements,  which  are 
very  obscure  in  the  immediate  neighbourhood  of  the  joint,  are  more  evident  the  gieater 
the  distance  is  from  the  posterior  end  of  the  rib.  The  means  of  union  between  the  ribs 
and  vertebrae  are  so  strong,  that  luxation  of  the  ribs  is  impossible  ;  and  the  causes  which 
would  tend  to  produce  it  would  break  the  neck  of  the  rib. 

Each  rib  is  capable  of  performing  all  these  motions ;  but,  as  they  vary  in  degree  in  the 
different  ribs,  we  must  examine  them  comparatively  in  the  series  of  costo-vertebral  ar- 
ticulations. The  eleventh  and  the  twelfth  ribs  possess  the  most  extensive  power  of 
motion.  They  owe  this,  1.  To  the  circumstance  of  their  being  scarcely  at  aU  united  to 
the  very  small  transverse  processes  ;  2.  To  the  loose  state  of  their  ligaments  ;  and,  3. 
To  the  almost  perfect  flatness  of  their  articulated  surfaces.  The  extent  of  their  move- 
ments inward  and  outward  should  also  be  noticed.  We  shall  find  these  movements 
but  less  pronounced,  in  the  eighth,  ninth,  and  tenth  ribs,  they  scarcely  exist  in  the  first 
seven  ribs. 

The  shape  of  the  head  of  the  first  rib  is  undoubtedly  favourable  to  mobility,  and  has 
suggested  the  idea  that  it  is  the  most  movable  of  all  the  ribs ;  but  the  articulation  of 
its  tubercle  with  the  transverse  process  of  the  first  dorsal  vertebra,  and  the  tightness 
of  its  ligaments,  suflSiciently  explain  why  this  opinion  is  erroneous. 

The  movements  which  take  place  in  the  second,  third,  fourth,  filth,  sixth,  and  seventh 
costo-vertebral  articulations  do  not  differ  sufficiently  to  require  any  special  mention. 

Movements  of  the  Chondro-sternal  Articulations. 

In  these  articulations  there  is  even  less  gUding  than  in  the  preceding.  The  anterior 
extremity  of  the  first  rib,  or,  rather,  of  the  cartilage  which  forms  its  continuation,  is  the 
least  movable  of  all ;  more  commonly,  it  is  completely  fixed  on  account  of  its  continu- 
ity with  the  sternum,  a  circumstance  which  neutralizes  the  favourable  conditions  for 
mobility  presented  by  its  posterior  extremity.  The  eleventh  and  twelfth  ribs,  whose 
anterior  extremities  are  connected  only  to  soft  parts,  are  the  most  movable.  The  mo- 
bility of  the  ribs  in  front  decreases  from  the  lower  to  the  upper  part  of  the  thorax ;  to 
this  rule  the  second  rib  is  an  exception,  chiefly  on  account  of  tlie  two  synovial  mem- 
branes at  its  chondro-sternal  articulation,  which  permit  of  greater  motion.  This,  how- 
ever, is  variable,  depending  as  it  does  on  the  absence  or  presence  of  an  articulation  be- 
tween the  first  and  second  bones  of  the  sternum,  and  upon  the  more  or  less  variable 
mode  in  which  these  two  pieces  are  articulated. 

Movements  of  the  Cartilages  upon  each  other. 

The  movements  of  this  kind  are  restricted  to  the  sixth,  seventh,  eighth,  ninth,  and 
tenth  ribs,  the  cartilages  of  which  alone  are  articulated  to  each  other.  They  are  simple, 
gliding  motions,  and  this  gliding  is  proportionate  to  the  looseness  of  the  ligaments. 
Hence  it  follows,  that  the  ribs  wliich  I  have  just  mentioned  are  always  moved  simul- 
taneously as  they  gUde  slightly  upon  each  other ;  whereas  the  superior  ribs  are  inde- 
pendent in  their  movements.  This  independence,  however,  is  not  as  great  as  it  might 
appear  at  first  sight,  on  account  of  the  interosseous  aponeuroses,  the  interosseous  mus- 
cles, and  the  superior  transverso-costal  ligament,  which  is  very  narrow  above,  and  forms 
below  large  and  shining  aponeurotic  laminae. 

It  results,  from  the  facts  above  stated,  that  the  most  movable  ribs  are  the  twelfth 
and  the  eleventh,  which  may  be  moved  upward  and  downward,  and,  at  the  same  time, 


134  ARTHROLOGY. 

enjoy,  in  the  highest  degree,  the  movements  of  projection  inward  and  outward ;  that 
the  first  rib  is  the  least  movable  of  all ;  that  the  superior  ribs  may  be  moved  isolatedly ; 
that  the  inferior  ribs  are  moved  all  together. 

Movements  of  the  entire  Rib. 

Since  we  now  know  all  the  elements  of  which  the  movement  of  the  ribs  is  composed, 
we  shall  easily  comprehend  the  play  of  each  of  those  bones  isolatedly,  and  the  play  of 
the  whole  thorax. 

The  movements  of  the  entire  rib  are  composed,  1.  Of  those  which  take  place  at  the 
sternal  and  vertebral  articulations  ;  and,  2.  Of  those  which  result  from  its  own  flexibility 
and  elasticity.  We  shall  endeavour  to  reduce  the  subject  to  its  most  simple  elements. 
Let  us  suppose,  then,  that  the  ribs  are  straight,  inflexible  levers  :  from  their  oblique  po- 
sition in  reference  to  the  vertical  axis  of  the  spinal  column,  their  elevation  will  increase 
the  width  of  the  intercostal  spaces ;  for  it  is  a  law  of  physics,  that  lines  which  are  ob- 
lique with  regard  to  another  line,  and  parallel  to  each  other,  become  farther  separated 
when  they  are  placed  perpendicularly  to  that  line.  Hence  it  follows,  that  the  contact  or 
the  overlapping  of  the  ribs  is  impossible  during  the  movement  upward  of  these  bones.  A 
second  effect  of  the  elevation  of  this  oblique  lever  is  the  advancement  of  the  anterior 
extremity  of  the  rib,  which  movement  increases  proportionately  to  the  length  of  the  le- 
ver ;  hence  results  an  increase  of  the  antero-posterior  diameter  of  the  thorax.  But  as 
the  ribs  are  curved  levers,  and  not  rectilinear,  in  assuming  the  horizontal  position,  their 
concavity  must  come  to  be  directed  perpendicularly  to  the  median  plane  formed  by  the 
mediastinum.  It  may  be  shown,  geometrically,  that  the  concavity  of  an  arc  which  falls 
perpendicularly  upon  a  plane,  includes  a  greater  space  than  when  it  falls  obliquely.  From 
the  elevation  of  the  ribs  results,  therefore,  an  increase  of  the  transverse  diameter  of  the 
thorax.* 

The  arcs  of  the  ribs,  however,  have  not  all  the  same  curvature :  each  rib  has  its  own 
peculiar  perimeter,  and  it  may  be  proved  that  the  more  curved  the  rib,  the  greater  is  the 
projection  outward  which  it  forms  when  elevated.  Lastly,  as  in  some  ribs  the  upper 
border  forms  the  segment  of  a  smaller  circle  than  the  lower,  the  movement  of  projection 
outward  is  proportionally  greater  in  these  than  in  the  other  ribs.  This  assertion  may 
be  experimentally  proved  by  imitating  the  movements  of  elevation  and  depression  on 
the  second  rib.  I-  The  greater  the  disproportion  between  the  curvature  of  the  superior 
and  that  of  the  inferior  border,  the  more  marked  will  be  the  projection  gjitward.  This 
is  the  reason  why  the  elevation  of  the  second  and  third  ribs,  when  they  are  bent  at  once, 
both  by  their  faces  and  their  borders,  produce  such  a  remarkable  increase  of  the  thoracic 
capacity. 

If  the  ribs  and  their  cartilages  were  inflexit)le  levers,  the  movements  of  elevation 
would  be  much  restrained ;  but,  by  a  mechanism,  of  which  we  find  no  instance  elsewhere, 
the  flexibility  of  these  levers  introduces  into  the  problem  a  power  which  is  most  impor- 
tant and  very  variable,  so  that  their  movements  are  much  more  marked  than  would  arise 
from  the  mobility  of  the  articular  surfaces.  These  movements  cannot  be  determined  by 
calculation.  Now  this  flexibility,  whence  results  a  movement  of  torsion  in  the  rib,  or 
of  rotation  round  an  axis,  represented  by  the  cord  of  the  arc  which  the  rib  forms,  is  in  a 
direct  ratio  to  the  length  of  the  ribs  and  their  cartilages,  and  the  flexibility  of  either. 
Indeed,  the  movements  of  the  ribs  are  much  more  considerable  in  children  and  women 
than  in  old  men ;  and  the  deficiency  of  mechanical  power  in  regard  to  breathing,  which 
corresponds  to  the  smallness  of  the  power  of  locomotion  in  old  men,  explains  the  sever- 
ity which  characterizes  asthma  and  all  the  diseases  of  the  lungs  at  this  age. 

We  shall  now  examine  the  movements  of  the  thorax  in  genercil. 

Movements  of  the  Thorax  in  general. 

The  general  movements  of  the  thorax,  which  result  from  those  partial  motions  we 
have  been  engaged  in  considering,  are,  1.  A  movement  of  dilatation,  corresponding  with 
the  act  of  inspiration ;  2.  A  movement  of  contraction,  corresponding  with  that  of  expi- 
ration. 

1 .  The  dilatation  of  the  thorax  is  caused  by  the  elevation  of  the  ribs.  By  this  move- 
ment, the  anterior  extremity  of  each  rib  is  carried  forward,  and  the  antero-posterior  di- 
ameter of  the  thorax  is  thus  increased  ;  the  most  eccentric  portion  of  the  rib  is  carried 
outward,  and  the  transverse  diameter  of  the  thorax  is  thereby  augmented.  There  is  a 
sort  of  antagonism  between  the  upper  and  lower  part  of  the  thorax,  with  regard  to  the 
direction  in  which  the  increase  of  its  capacity  is  effected :  in  the  upper  part  the  trans- 
verse diameter  is  most  augmented  ;  in  the  lower,  the  antero-posterior  diameter. 

The  most  movable  point  in  the  superior  ribs  is  at  the  centre  of  the  curvature  ;  the 
most  movable  point  of  the  inferior  ribs  is  at  the  junction  of  the  ribs  and  the  cartilages 
But  the  columns  to  which  the  extremities  of  the  ribs  are  attached  are  not  equ£iUy  mo- 

*  BoreUi,  t.  ii.,  p.  177. 

t  From  measurements  taken  by  Haller,  it  appears  that  the  second  rib  is  the  most  elevated  during  inspira- 
tion ;  and  if  this  may  be  doubted,  it  cannot  be  denied  that  its  eccentric  movement  is  greater  than  that  of  ant 
»f  the  other  ribs. 


ARTICULATIONS   OF   THE   SHOULDER.  135 

vable  :  if  the  posterior  extremity  is  fixed,  the  anterior  extremity  may  be  moved  from  its 
place.  This  circimistance  does  not  oppose  the  transverse  enlargement  being  produced 
by  the  elevation  of  the  arcs  of  the  ribs,  though  it  introduces  a  new  condition  into  the 
problem,  to  wit,  the  elevation  of  the  anterior  column  or  the  sternum.  So  long  as  the 
movement  of  elevation  of  the  ribs  is  limited  to  the  costo-vertebrcd  articulations  and  a 
slight  flexibility  of  the  ribs  and  their  cartilages,  the  sternum  scarcely  participates  in  the 
motion  ;  but  when  the  elevation  is  carried  beyond  a  certain  point,  when  all  the  powers 
of  inspiration  are  in  activity,  when  there  is  an  integral  movement  of  the  thorax,  which 
has  not  been  sufficiently  distinguished  from  the  partijd  movement,  then  the  sternum  is 
carried  upward  with  the  ribs,  then  the  first  two  ribs,  which  we  have  represented  as  the 
essential  props  of  the  sternum,  are  themselves  elevated,  and  this  elevation  must  be  the 
Scune  as  that  of  all  the  other  ribs,  and  must,  therefore,  be  proportionately  more  consider- 
able. Does  the  sternum  perform  an  angular  motion  during  its  elevation,  as  Haller  ima- 
gined 1  On  placing  the  thorax  between  two  parallel  planes,  and  on  executing  a  forci- 
ble movement  of  inspiration,  we  feel  at  the  inferior  portion  a  pressure,  which  seems  to 
indicate,  in  this  inferior  portion,  a  movement  of  projection  forward.  The  lever  formed 
by  the  inferior  ribs  being  longer,  it  seems,  indeed,  as  though  there  ought  to  be  an  angular 
motion ;  but  it  will  be  observed  that  there  is  no  pression  tending  to  diminish  the  curve 
which  is  described  by  the  ribs  ;  that  therefore  the  two  halves  of  the  arc  which  the  curves 
represent  do  not  recede  from  each  other,  and  that  the  powers  of  elevation  simply  draw 
all  the  anterior  extremities  of  the  ribs  upward  ;  indeed,  the  sternum  is  simply  elevated 
near  the  cervic£d  region,  retaining;  its  primitive  direction,  as  Borelli  had  previously  well 
pointed  out ;  considering  the  flexibility  of  the  cartilages,  the  angular  motion  is  almost 
impossible. 

The  enlargement  of  the  thorax  is  effected  by  the  elevation  of  the  ribs,  and  takes  place 
either  transversely  forward  or  backward.  The  enlargement  of  the  thorax  in  a  vertical 
direction  is  produced  by  a  totally  different  mechanism,  the  contraction  of  the  diaphragm, 
of  which  we  shall  speak  hereafter. 

2.  Let  us  now  speak  of  the  contraction  of  the  thortix.  This  contraction  is  effected  by 
the  depression  of  the  ribs.  In  the  first  stage,  the  contraction  is  passive,  because  it  re- 
sults from  the  elasticity  of  the  cartilages,  which,  on  account  of  the  relaxing  of  the  eleva- 
tor muscles,  cease  to  be  maintained  in  a  state  of  torsion,  and  therefore  react  and  restore 
the  rib  to  its  primitive  position,  so  that  the  rib  and  cartilage,  according  to  the  ingenious 
remark  of  Haller,  are  alternately  the  cause  of  their  respective  movements.  It  ought  to 
be  remarked,  that  the  movement  of  depression  is  much  more  limited  than  the  movement 
of  elevation  ;  and  I  may  justly  regard  the  superior  transverso-costal  hgament  as  being 
destined  to  impose  particular  limits  to  that  depression,  during  which  the  intercostal 
spaces  are  narrowed.  We  may  regard  as  a  powerful  auxiliary  of  the  depression  and  the 
contraction  of  the  thorax  the  movement  of  projection  inward,  especially  in  the  last  five 
ribs,  which  are  in  certain  respects  depending  upon  each  other.  This  movement  of  pro- 
jection inward  is  opposed  to  the  transverse  dilatation  or  the  movement  of  projection  out- 
ward, which  takes  place  especially  at  the  superior  portion,  as  has  been  seen  above,  and 
as  is  shown  every  day  by  the  use  of  the  corsets.  Afterward  we  shall  see  that  the  great 
inspiratory  powers,  or  powers  of  elevation,  occupy  the  superior  portion  of  the  thorax,  as 
the  great  expiratory  powers  occupy  the  inferior  portion.  To  the  integral  elevation  of 
the  thorax,  in  the  most  considerable  degree  of  contraction,  corresponds  an  integral  de- 
pression, and  this  depression  of  the  ribs  is  directly  produced  by  muscles  which  bear  the 
name  of  expiratory  muscles. 


ARTICULATIONS  OF  THE  SUPERIOR  OR  THORACIC  EXTREMITIES. 

Articvlaiions  of  the  Shoulder. — Scapulo-humeral, — ■Humero-cuhital. — Radio-cubital. — Radio- 
carpal.— Of  the  Carpus  and  Metacarpus. — Of  the  Fingers. 

Articulations  of  the  Shoulder. 
The  two  bones  of  the  shoulder  are  articulated  together ;  the  clavicle  is  also  united 
with  the  sternum  and  the  first  rib.   There  are,  therefore,  two  orders  of  articulations :  1 
The  intrinsic  articulations  of  the  shoulder,  viz.,  the  acromio-  and  coraco-clavicular  artic- 
ulations ;  2.  The  extrinsic,  or  the  sterno-  and  costo-clavicular. 

The  Acromio-  and  Coraco-clavicular  Articulations. 

The  clavicle  is  articulated,  1.  With  the  acromion  by  its  external  extremity,  the  acro- 
mio-clavicular  articulation ;  2.  With  the  coracoid  process  by  its  lower  surface,  the  coraco- 
clavicular  articulation. 

Preparation. — Remove  the  skin,  the  cellular  tissue,  and  the  muscles  which  surround 
the  joints ;  separate  the  acromion  from  the  spine  of  the  scapula  ;  remove,  in  succession, 
the  different  layers  of  the  superior  acromio-clavicular  ligament,  so  as  to  be  able  to  judge 
of  its  thickness.  Make  a  vertical  section  of  the  acromio-clavicular  articulation,  so  as  to 
be  able  to  observe  the  thickness  of  the  ligaments  and  articular  cartilages. 


136  ARTHROLOGY. 

Aeromio-clavicular  Articulation  {fig-  69). 

Articular  Surfaces. — ^The  clavicle  and  the  acromion  process  oppose  to  each  other  a 
plane,  elliptical  surface,  with  its  greatest  diameter  directed  from  before  backward.  The 
articular  surface  of  the  clavicle  looks  somewhat  obliquely  downward  and  outward,  the 
acromial  facette  looks  obliquely  upward  and  inward.  The  extent  of  these  surfaces  va- 
ries greatly  in  individued  cases,  dependant  on  the  degree  of  exercise  to  which  the  joint 
is  subjected.* 

Means  of  Union  and  Promsion  for  facilitating  Motion. — These  are,  1.  An  intcr-articidar 
cartilage,  first  pointed  out  by  Weitbrecht ;  it  is  by  no  means  constant,  and,  when  it  does 
exist,  occupies  only  the  upper  half  of  the  articulation.  2.  An  orbicular  fibrous  capsule  {d, 
fig.  69),  which  is  very  thick  above  and  behind,  and  very  thin  below.  It  is  composed  of 
distinct  bundles,  which  are  much  longer  behind  than  in  front,  and  are  strengthened  by 
some  fibres  belonging  to  the  aponeurosis  of  the  trapezius  muscle  ;  it  is  not  only  attached 
to  the  upper  edge  of  the  articular  surface,  but  also  to  some  inequalities  upon  the  upper 
surface  of  the  acromion.  It  is  composed  of  several  layers,  the  deepest  being  the  shortest. 
3.  A  synovial  membrane,  of  a  very  simple  construction,  supported  below  by  adipose  tissue. 

Coraco-clavicular  Articulation  {fig.  69). 
There  can  be  no  doubt  concerning  the  existence  of  an  articulation,  where  two  surfaces 
are  contiguous,  and  capable  of  a  gliding  motion  on  each  other  ;  one  of  them,  the  coracoid, 

being  almost  always  covered  with  carti- 
lage and  a  synovial  membrane  ;  and  the 
other,  the  clavicular,  presenting  some- 
times a  considerable  process  for  this  ar- 
ticulation. 

The  means  of  union  are  two  ligaments, 
or,  rather,  two  distinct  ligamentous  bun- 
dles, a  posterior  and  an  anterior  :  they 
are  called  coraco-clavicular. 

1.  The  posterior  ligament,  named  also 
the  conoid  or  radiated  (c,  fig.  69),  is  trian- 
gular, and  directed  vertically ;  it  com- 
mences by  a  narrow  extremity,  at  the 
base  of  the  coracoid  process,  and  is  inserted  into  a  series  of  tubercles  on  the  posterior 
edge  of  the  clavicle,  near  its  outer  extremity. 

2.  The  anterior  ligament  (/)  {trapezoid  ligament  of  Boyer)  arises  from  the  internal  edge 
of  the  coracoid  process,  and  from  the  whole  extent  of  the  rough  projection  on  the  base 
of  this  process  ;  from  this  it  proceeds  very  obliquely  to  the  ridge  on  the  lower  surface, 
near  the  external  end  of  the  clavicle. 

The  two  coraco-clavicular  ligaments  are  continuous,  and  can  only  be  distinguished  by 
the  direction  of  their  fibres. 

We  might  with  propriety  range  among  the  means  of  union  of  this  joint  an  aponeurotic 
lamina,  to  which  much  importance  has  been  attached  in  surgical  anatomy,  and  which  is 
known  by  the  name  of  the  costo-clavicular  aponeurosis,  or  costo-coracoid  ligament.  It 
may  be  easily  felt  under  the  pectoralis  major  in  emaciated  individuals  :  it  extends  from 
the  inner  edge  of  the  coracoid  process  to  the  lower  surface  of  the  clavicle,  and  converts 
the  groove  for  the  subclavius  muscle  into  a  canal. 

Mechanism  of  the  Acromio-  and  Coraco-clavicular  Articulations. 
The  acromio-  and  coraco-clavicular  articulations  perform  well-marked  gliding  move- 
ments ;  and,  in  addition,  the  scapula  rotates  forward  and  backward  upon  the  clavicle  to  a 
considerable  extent.  In  order  to  have  a  correct  idea  of  these  motions  and  their  mecha- 
nism, it  is  necessary  to  procure  a  shoulder  with  the  ligaments  still  attached,  and  to  ro- 
tate the  scapula  backward  and  forward.  It  will  be  then  seen  that  the  scapula  turns  round 
an  imaginary  axis  passing  through  its  middle.  The  looseness  of  the  posterior  half  of  the 
orbicular  and  of  the  coraco-clavicular  ligaments  permits  this  rotatory  motion ;  of  the  two 
coraco-clavicular  ligaments,  one  limits  the  rotation  forward,  while  the  other,  which,  as 
we  have  observed,  runs  in  an  opposite  direction,  hmits  the  rotation  backward.  Although 
these  motions  are  pretty  extensive,  they  never  give  rise  to  dislocation,  which  can  only 
be  produced  by  falls  on  the  top  of  the  shoulder,  the  coraco-clavicular  ligaments  being 
lacerated  if  the  luxation  be  complete.  Incomplete  luxations  may,  however,  take  place 
without  laceration  of  these  ligaments. 

The  Sterno-clavicular  Articulation  {fig.  69). 

The  articulation  of  the  inner  end  of  the  clavicle  is  composed  of  the  sterna-clavicular 
and  the  costo-clavicular  articulations. 

Preparation. — Saw  through  the  clavicles  vertically  at  their  middle,  and  also  the  first 
ribs  at  corresponding  points  ;  and  meet  these  two  sections  by  a  horizontal  division  of  the 

*  In  indiyiduals  who  have  excrciscil  the  upper  extremities  very  much,  these  surfaces  are  uneven,  and 
unequally  incrusted  '"•th  np^lv-fonned  cartilage. 


ARTICULATIONS    OF    THE   SHOULDER.  1^7 

Sternum.  In  order  to  see  the  interior  of  the  sterno-clavicular  joint,  open  the  fibrous  cap- 
sule along  the  edge  of  the  sternum  above,  or,  rather,  make  a  horizontal  cut,  which  will 
divide  it  into  two  parts,  an  upper  and  an  under. 

In  order  to  examine  the  costo-clavicular  articulation,  open  the  synovial  membrane  be- 
hind. 

The  sterno-clavicular  articulation  belongs  to  those  which  are  formed  by  rmitual  reception. 

Articular  Surfaces. — The  articular  surface  of  the  sternum  is  transversely  oblong  con- 
cave in  the  same  direction,  and  convex  from  before  backward ;  it  looks  obliquely  upward 
and  outward,  and  is  situated  on  the  side  of  the  notch  on  the  upper  part  of  the  sternum. 

1.  The  articular  surface  of  the  clavicle  is  oblong  from  before  backward,  slightly  concave 
in  the  same  direction,  and  convex  transversely.  From  the  respective  configuration  of 
these  surfaces  a  mutual  jointing  results,  and  the  short  diameter  of  the  one  corresponds  to 
the  long  diameter  of  the  other ;  so  that  the  end  of  the  clavicle  overlaps  the  surface  of  the 
sternum  in  front  and  behind,  and  the  surface  of  the  sternum  projects  beyond  that  of  the 
clavicle  on  the  inside  and  the  outside.* 

2.  There  is  an  inter-articular  lamina  of  cartilage  (i.  Jig.  69)  between  the  articular  sur- 
faces, which  is  moulded  upon  them,  and  is  very  tliick,  especially  at  the  edges.  It  is 
sometimes  perforated  in  the  centre.  +  It  is  so  closely  united  by  its  circumference  to  the 
orbicular  Hgament  that  it  is  impossible  to  separate  them :  it  adheres  below  to  the  carti- 
lage of  the  first  rib,  and  above  and  behind  to  the  clavicle. 

Means  of  Union. — These  are,  1.  The  orbicular  ligament  {I,  fig.  69).  This  name  may  be 
given  to  the  fibrous  capsule  which  surrounds  the  joint  in  all  directions.  The  fibres  which 
compose  it  have  been  regarded  as  forming  two  distinct  bundles,  known  by  the  name  of 
anterior  and  posterior  ligaments  ;  but  it  is  impossible  to  distinguish  between  them.  Fi- 
bres proceed  from  all  parts  of  the  circumference  of  the  articular  surface  of  the  clavicle, 
obliquely  downward  and  inward,  to  the  circumference  of  the  articular  surface  of  the  ster- 
num. The  capsule  is  not  of  equal  thickness  throughout ;  it  is  thinner,  and  somewhat 
looser,  in  front  than  behind,  which  may  partly  account  for  the  more  frequent  luxations 
of  the  clavicle  forward  than  backward. 

2.  The  inter-clavicular  ligament  (wi,  Jig.  69),  consisting  of  a  very  distinct  bundle  stretch 
ing  horizontally  above  the  fourchette  of  the  sternum,  from  the  upper  part  of  the  innei 
end  of  one  clavicle  to  the  inner  end  of  the  other.     This  ligament,  which  is  much  nearer 
the  posterior  than  the  anterior  part  of  the  joint,  establishes  a  sort  of  continuity  between 
the  clavicles.     It  is  the  only  direct  means  of  union  between  the  two  shoulders. 

3.  There  are  two  synovial  capsules  in  this  joint.  That  which  is  between  the  sternum 
and  the  inter-articular  cartilage  is  more  loose  than  that  between  the  cartilage  and  the 
clavicle. 

The  Costo-clavicular  Articulation  {Jig.  69). 
The  articulation  between  the  clavicle  and  the  cartilage  of  the  first  rib  is  an  arthrodia. 
It  is  formed  between  an  articular  surface,  which  almost  always  exists  on  the  lower  sur- 
face of  the  clavicle,  and  a  corresponding  facette  on  the  upper  surface  of  the  inner  end 
of  the  first  rib,  at  its  junction  with  the  cartilage.  There  is,  in  this  articulation,  a  syno- 
vial membrane,  which  is  loose,  especially  behind.  There  is  only  one  ligament,  the  cos- 
to-clavicular {g,  Jig.  66),  a  thick,  strong  bundle  of  fibres,  quite  distinct  from  the  tendon  of 
the  subclavius  muscle,  which  is  placed  in  front  of  it.  It  is  fixed  to  the  inner  part  of  the 
first  costal  cartilage,  and  is  directed  very  obliquely  upward  and  outward,  to  be  inserted 
into  the  under  surface  of  the  clavicle,  to  the  inner  side  of  the  articular  facette. 

Mechanism  of  the  Sterno-clavicular  Articulation. 

This  articulation  is  the  movable  centre  of  the  motions  of  the  shoulder  and  of  the 
whole  upper  extremity ;  and  hence  the  utility  of  an  inter-articular  cartilage,  to  obviate 
tte  effects  of  blows  or  pressure  :  hence,  also,  the  wearing  away  of  this  cartilage,  the  de- 
formity and  wasting  of  the  articular  surfaces,  the  depression  of  the  right  sternal  facette, 
and,  lastly,  the  difference  in  the  size  of  the  sternal  extremities  of  the  right  and  left 
clavicles. 

This  articuation,  like  all  those  effected  by  mutual  reception,  admits  of  motions  in 
every  direction  :  viz.,  upward,  downward,  forward,  backward ;  and  of  circumduction, 
resulting  from  the  preceding,  but  not  of  rotation. 

1.  Movement  of  Elevation. — In  this  the  sternal  facette  of  the  clavicle  glides  downward 
upon  the  corresponding  surface  of  the  sternum ;  the  inter-clavicular  ligament  is  relaxed ; 
the  cartilage  of  the  first  rib  comes  in  contact  with  the  inner  extremity  of  the  clavicle, 
limits  the  degree  of  elevation,  and  prevents  displacement. 

2.  Movement  of  Depression. — In  this  the  sternal  end  of  the  clavicle  glides  in  the  oppo 
site  direction  ;  the  articular  surfaces  of  the  costo-clavicular  articulation  press  strongly 

*  Bichat  considers  that  this  arrangement  of  the  articular  surfaces  predisposes  to  luxation  ;  it  appears  to  ma 
to  have  a  precisely  opposite  effect,  as  it  permits  tho  surfaces  to  move  upon  each  other  to  a  considerable  extent 
without  being  separated.  i,-  i,   i, 

t  In  a  great  number  of  cases  this  ligament  is  found  partially  wasted  by  the  continued  pressure  to  which  the 
joint  is  subjected. 

s 


138 


ARTHBOLOGY. 


against  each  other,  and  limit  the  extent  of  this  movement.  It  should  be  remarked,  that 
in  this  movement  the  subclavian  artery  is  compressed  betvi^een  the  clavicle  and  the  first 
rib,  sometimes  so  completely  as  to  arrest  the  circulation  in  the  limb. 

3.  In  the  movement  of  the  shoulder  backward,  the  inner  end  of  the  clavicle  glides  for- 
ward upon  the  surface  of  the  sternum ;  the  anterior  part  of  the  orbicular  capsule  is 
stretched ;  and  if  the  movement  is  carried  beyond  a  certain  point,  the  capsule  is  torn, 
and  the  clavicle  dislocated  forward. 

4.  In  the  foricard  movement  of  the  shoulder,  the  inner  end  of  the  clavicle  glides  back- 
ward. The  anterior  part  of  the  orbicular  ligament  is  relaxed,  and  the  posterior  part 
stretched  ;  as,  also,  the  inter-clavicular  ligament,  which,  as  we  have  seen,  is  nearer  the 
back  than  the  front  of  the  joint.  In  this  motion  luxation  may  take  place  backward.  It 
may  be  remarked  that,  of  all  the  movements  of  the  shoulder,  the  one  described,  in  which 
the  clavicle  is  likely  to  be  dislocated  backward,  is  the  most  uncommon. 

The  movement  of  circumduction  is  more  extensive  forward  and  upward  than  backward. 
The  motions  at  the  sterno-clavicular  articulation  are  very  circumscribed  in  themselves  , 
but  when  transmitted  by  the  lever  of  the  clavicle,  they  become  very  considerable  at  the 
apex  of  the  shoulder. 

Mechanism  of  the  Costo-clavicular  Articulation. 

This  articulation,  which  may  be  regarded  as  a  dependance  of  the  sterno-clavicular, 
admits  of  very  limited  motions,  subordinate  to  those  of  the  joint  last  described. 

The  Scapulo-humeeal  Articulation  {figs.  69  and  70). 
Preparation. — Separate  the  upper  extremity  from  the  trunk,  either  by  disarticulating 
the  clavicle  at  its  sternal  end,  or  by  dividing  it  through  the  middle  ;  2.  Detach  the  del- 
toid from  its  origin  ;  3.  Detach  the  supra  and  infra  spinati  muscles,  the  teres  minor  and 
subscapularis,  proceeding  from  the  scapula  to  the  humerus  ;  4.  Observe  the  adhesion  of 
the  tendons  of  these  muscles  to  the  capsular  ligament ;  5.  Divide  the  capsule  trans- 
versely, after  having  studied  its  external  aspect. 

The  scapulo-humeral  articulation  belongs  to  the  class  of  enarthroses. 
Articular  Surfaces. — These  are  the  glenoid  cavity  of  the  scapula,  slightly  concave,  of 
an  oval  form,  with  the  large  end  downward,  and  looking  directly  outward  ;  and  the  head 
of  the  humerus,  consisting  of  about  a  third  of  a  sphere,  and  presenting  a  surface  three  or 
four  times  more  extensive  than  the  glenoid  cavity.  The  axis  of  the  head  of  the  hume- 
rus forms  a  very  obtuse  angle  with  that  of  the  shaft  of  the  bone.* 

These  two  surfaces  are  covered  by  a  layer  of  cartilage,  which,  on  the  head  of  the  hu- 
merus, is  thicker  at  the  centre  than  at  the  circumference  ;  while  the  reverse  obtains  in 
the  glenoid  cavity. 

Glenoid  Ligament  (a,  fig.  70). — This  is  a  fibrous  circle,  which  surrounds  the  margin  of 
Fig.  70.  the  glenoid  cavity,  and  appears  to  be  formed  by  the  bifur- 

cation of  the  tendon  of  the  long  head  of  the  biceps  ;  but  it 
is  also  partly  composed  of  fibres  proper  to  itself,  which 
stretch  along  the  margin,  arising  from  one  point  and  ter- 
minating in  another.  Notwithstanding  this  addition,  the 
head  of  the  humerus  is  still  too  large  to  be  received  into 
the  cavity,  so  that  a  portion  of  it  is  always  in  contact  with 
the  capsular  ligament ;  an  inconvenience  that  is  obviated, 
in  some  measure,  by  the  existence  of  a  supplementary 
cavity,  as  we  shall  presently  see.  The  scapulo-humeral  ar- 
ticulation is  therefore  one  formed  by  juxtaposition,  and  not 
by  reception ;  from  which  arrangement  it  has  lately  been 
classed  among  the  arthrodial  articulations. 

Means  of  Union. — Like  all  enarthroses,  there  is  here  a  fibrous  capsule,  or  capsular  lig- 
ament (r,  figs.  69  and  70),  a  sac  with  two  openings,  which  extends  from  the  margin  of 
the  glenoid  cavity  to  the  anatomical  neck  of  the  humerus,  t  This  capsule  is  remarkable 
for  its  laxity.  In  fact,  it  is  so  capacious  that  it  could  lodge  a  head  twice  as  large  as  that 
of  the  humerus,  and  is  so  long  that  it  will  allow  the  articular  surfaces  to  be  separated 
for  more  than  an  inch  ;  the  only  example  of  so  great  a  separation  without  laceration  of 
the  ligament.t 

There  is  this  peculiarity  in  the  fibrous  capsule  of  the  shoulder-joint,  that  it  is  incom- 
plete in  one  part,  its  place  being  there  supplied  by  the  tendons  of  the  surrounding  mus- 
cles. In  no  joints,  in  fact,  have  the  muscles  and  tendons  more  effect  in  strengthening 
the  articulation  :  they  are,  in  a  manner,  identified  with  it.  There  are  a  great  many  varie- 
.ies  in  this  respect.   The  fibrous  capsule  is  so  much  stronger,  as  it  is  less  adherent  to  the 

*  Such  is  the  shortness  of  the  neck  of  the  humerus,  that  its  head,  which  looks  upward  and  inward,  would 
6e  almost  entirely  included  between  the  prolonged  planes  of  the  body  of  the  humerus. 

t  It  should  be  remarked,  however,  that  the  fibrous  capsule  does  not  terminate  directly  at  the  anatomical 
neck  of  the  humerus,  but  is  prolonged  a  little  downward,  and  becomes  blended  with  the  insertions  of  the  ten- 
dons of  the  supra  and  infra  spinati  and  subscapularis. 

i  In  paralysis  of  the  deltoid,  the  head  of  the  humerus  is  so  far  separated  from  the  glenoid  cavity  thai  two 
fingers  may  be  inserted  betweeu  the  articular  surfaces. 


AKTICULATtONS    OF    THE   SHOULDER.  189 

surrounding  tendons.  The  following  are  the  relations  of  the  capsule :  1.  Below,  in  the 
variable  space  between  the  subscapularis  and  teres  minor,  it  corresponds  to  the  cellular 
tissue  of  the  axilla,  or,  rather,  to  the  thin  edges  of  the  muscles  just  mentioned :  the  head 
of  the  humerus  may,  therefore,  be  easily  felt  by  the  fingers  introduced  deeply  into  the 
axilla.  2.  Above  and  on  the  outside,  it  is  in  contact  with  the  tendon  of  the  supra-spi- 
natus,  from  which  it  is  difficult  to  separate  it,  and  is  also  in  relation,  though  not  immedi- 
ately, with  the  arch  formed  by  the  acromion  and  clavicle  with  the  deltoid  muscle.  3.  In 
front,  it  corresponds  to  the  subscapular  muscle,  from  which  it  may  be  easily  separated. 
4.  Behind,  it  corresponds  to  the  tendons  of  the  supra  and  infra  spinatus,  which  are  more 
or  less  adherent  to  it,  and  the  teres  minor,  which  does  not  adhere  to  it.  As  to  its  struc- 
ture, it  is  composed  of  fibres  stretched  irregularly  from  the  neck  of  the  humerus  to  the 
circumference  of  the  glenoid  cavity.  Its  thickness  is  not  great,  nor  is  it  equal  through- 
out, being  most  considerable  below  and  in  front ;  but  the  capsule  is  strengthened  above 
by  a  considerable  bundle  of  fibres  (s,  fig.  69),  called  the  coracoid  ligament,  coraco-humeral 
ligament,  or  accessory  ligament  of  the  fibrous  capsule,  which  arises  from  the  anterior  edge 
of  the  coracoid  process,  and  spreads  out  on  the  capsule.  This  capsule  always  presents 
an  opening  or  an  interruption  above  and  before,*  on  a  level  with  the  superior  border  of 
the  subscapularis,  which  covers  the  opening  in  part ;  or,  rather,  between  this  border 
and  the  coracoid  process.  This  opening  is  of  an  oval  form ;  its  greatest  diameter  is 
horizontal ;  its  large  extremity  is  turned  outward,  and  its  small  extremity  inward.  The 
circumference  of  this  opening,  which  is  large  enough  to  admit  the  point  of  the  index  fin- , 
ger,  is  perfectly  smooth,  thick,  and  looks  like  mother-of-pearl,  especially  in  its  inferior 
half.  This  opening  is  traversed  by  a  considerable  prolongation  of  the  synovial  mem- 
brane, which  reaches  the  basis  of  the  coracoid  process,  and  then  extends  between  the 
tendon  of  the  subscapularis  and  the  cavity  which  bears  the  same  name.  This  cone- 
shaped  prolongation  is  variable  with  respect  to  its  extent,  and  appears  to  have  no  other 
object  except  to  facilitate  the  gliding  of  the  tendon  of  the  subscapularis  under  the  cora- 
coid arch  and  against  the  border  of  the  glenoid  cavity.  By  distending  the  articular  cap- 
sule in  several  subjects,  Mr.  Bonamy  has  demonstrated  this  disposition  to  my  perfect 
satisfaction.  I  have  been  able  to  see  that  the  synovial  prolongation  is  sometimes  divi- 
ded into  several  cells  by  incomplete  walls,  by  which  this  distended  prolongation  acquires 
a  crimpled  aspect.  Sometimes  several  of  these  cells  are  totally  distinct  from  the  syno- 
vial membrane. 

Inter-articular  Ligament. — This  name  may,  with  propriety,  be  applied  to  the  tendon  (t, 
fig.  70)  of  the  long  head  of  the  biceps,  which,  arising  from  the  upper  part  of  the  glenoid 
cavity,  turns  like  a  cord  over  the  head  of  the  humerus,  and  passes  along  the  bicipital 
groove.  It  acts  by  keeping  the  head  of  the  humerus  applied  to  the  glenoid  cavity,  and 
forms  a  sort  of  arch  that  supports  the  bone  when  it  is  forced  upward.  In  two  subjects, 
I  found  this  tendon  terminating  by  a  strong  adhesion  in  the  bicipital  groove,  and  thus 
justifying  the  name  of  inter-articular  ligament,  which  I  have  applied  to  it :  the  tendon 
for  the  long  head  of  the  biceps  took  its  origin  from  the  same  groove.  I  consider  this 
division  of  the  tendon  to  have  been  accidental,  for  the  bicipital  groove  was  depressed, 
and  the  inter-articular  ligament  flattened,  and,  as  it  were,  lacerated. 

The  synovial  capsule  is  the  simplest  of  all  in  regard  to  its  disposition.  It  lines  the 
fibrous  capsule  and  the  tendons  which  replace  it,  and  is  reflected,  on  one  side,  on  the 
neck  of  the  humerus,  and,  on  the  other,  upon  the  border  of  the  glenoid  cavity,  to  be  lost 
upon  the  circumference  of  the  articular  cartilages.  It  is  remarkable,  inasmuch  as,  1.  It 
forms  a  fold  round  the  tendon  of  the  biceps,  which  is  prolonged  into  the  bicipital  groove, 
and  terminates  below  by  a  cul-de-sac  or  circular  fold,  which  prevents  the  effusion  of  the 
synovia ;  2.  It  is  open  in  one  or  two  points,+  and  presents  two  prolongations  communi- 
cating with  the  synovial  bursse  of  the  subscapularis  and  infra-spinatus. 

Supplementary  Cavity. — ^We  may  regard  as  a  dependance  of  the  scapulo-humeral  artic- 
ulation the  vaulted  arch  formed  by  the  coracoid  and  acromion  processes,  and  the  liga- 
ment which  unites  them.  In  shape  it  corresponds  to  the  head  of  the  humerus,  and  is  so 
constructed  that  the  coracoid  process  prevents  displacement  inward  ;  the  acromion  pre- 
vents it  upward  and  outward ;  and  the  ligament  between  them  opposes  dislocation  di- 
rectly upward.  This  provision  evidently  compensates  for  the  incomplete  reception  of 
the  head  of  the  humerus  in  the  glenoid  cavity.  A  circumstance  which  proves  the  use 
fulness  of  this  vault,  and  the  frequent  contacts  which  it  must  have  with  the  humerus,  is 
the  presence  of  a  synovial  capsule,  situated  between  the  coraco-acromion  vault  on  one 

*  I  have  seen  this  opening  divided  into  two  unequal  portions  by  a  fibrous  bundle,  strong,  looking  like  mother- 
of-pearl,  and  resemliling  a  little  tendon.  Often  1  have  met  a  second  interruption  of  the  fibrous  capsule  on  a 
level  with  the  concave  border  of  the  acromion  process,  which  concave  border  acts  as  a  real  retum-puHey  for 
the  infra-spinatus  muscle,  and  is  analogous  to  the  return-pulley  presented  by  the  basis  of  the  coracoid  process 
to  the  subscapularis  muscle.  When  the  capsule  is  perforated  at  this  point,  the  synovial  membrane  gives  oflf  a 
prolongation,  which  serves  as  a  gliding  capsule  for  the  tendon  of  the  infra-spinatus. 

t  [Although  the  synovial  capsule  of  the  shoulder-joint  is  thus  occasionally  prolonged  into  the  bursoe  mucosal 
connected  with  the  tendons  of  these  muscles,  it  must  not,  therefore,  be  supposed  that  it  is  an  exception  to  the 
general  rule  that  membranes  of  this  nature  always  form  shut  sacs  ;  in  such  cases,  the  three  structures  consti- 
tute one  coiitiiiuuus  cavity.] 


140  -        "  •    .  ARTHROLOGY. 

side,  and,  on  the  other,  the  tendon  of  the  infra-spinatus  and  the  great  trochanter  of  the 
humerus.  The  study  of  the  coraco-acromion  vault  cannot,  therefore,  be  separated  from 
the  study  of  the  scapulo-humeral  articulation,  either  under  an  anatomical  and  physiolo- 
gical or  surgical  point  of  view. 

The  Coraco-acromial  Ligament. 
This  ligament  (m,  figs.  69  and  70)  forms  part  of  the  vault  we  have  described :  it  is  a 
triangular  bundle  of  radiating  fibres,  which  extends  from  the  apex  of  the  acromion  to  the 
A^hole  length  of  the  posterior  edge  of  the  coracoid  process.  Its  external  edge  becomes 
Ainner,  and  is  continued  into  an  aponeurotic  lamina  below  the  deltoid  muscle,  and  sep- 
arating that  muscle  from  the  joint.  Its  anterior  and  its  posterior  bundles  are  very  thick, 
folded  upon  each  other,  and  look  like  mother-of-pearl ;  its  middle  bundles  are  much  less 
thick.  It  is  lined  below  by  a  synovial  membrane,  and  is  separated  from  the  clavicle  by 
fatty  tissue.* 

Mechanism  of  the  Scapulo-humeral  Articulation. 

The  scapulo-humeral  articulation  admits  of  the  most  extensive  movements  of  any 
joint  in  the  body :  it  is  capable  of  every  kind  of  motion,  viz.,  forward  and  backward,  and 
also  those  of  adduction,  abduction,  circumduction,  and  rotation. 

Forward  and  Backward  Motions. — In  these  the  head  of  the  humerus  rolls  upon  the  gle- 
noid cavity,  and  moves  round  the  axis  of  the  neck  of  the  humerus,  while  the  lower  extrem- 
ity of  the  bone  describes  the  arc  of  a  circle,  of  which  the  centre  is  at  the  joint,  the  radius 
being  represented  by  the  humerus.!  The  forward  movement  is  very  extensive,  and  may 
be  carried  so  far  that  the  humerus  may  take  a  vertical  direction  exactly  opposite  to  the 
natural  one.  The  motion  backward  is  produced  by  the  same  mechanism  ;  the  head  of 
the  humerus  turns  upon  its  axis.  This  movement  is  limited  by  the  contact  of  the  head 
of  the  humerus  with  the  coracoid  process,  without  which  dislocation  forward  would  be 
very  easily  produced.  It  should  be  remarked  that,  in  any  considerable  movement  of  the 
humerus  forward,  the  scapula  is  also  moved,  performing  that  sort  of  rotation  which  we 
spoke  of  when  considering  the  mechanism  of  the  shoulder.  And  this  combination  of  the 
movement  forward  of  the  arm  and  the  movement  of  rotation  of  the  shoulder  renders 
every  kind  of  displacement  extremely  difficult  in  exercising  the  movements  of  the  arm 
forward. 

The  movement  outward,  or  abduction,  is  the  most  remarkable.  It  belongs  exclusively 
to  animals  possessed  of  a  clavicle.  In  it  the  head  of  the  humerus  does  not  turn  upon  an 
axis  ;  it  glides  downward  upon  the  glenoid  cavity,  and  presses  upon  the  lower  part  of 
the  capsule.  The  shape  of  the  glenoid  cavity,  which  has  its  long  diameter  vertical,  and 
its  broad  part  below,  is  advantageous  as  regards  this  motion.  When  abduction  is  car- 
ried so  far  that  the  humerus  forms  a  right  angle  with  the  axis  of  the  trunk,  a  great  part 
of  the  head  of  the  bone  is  below  the  glenoid  cavity.  If,  while  in  this  condition,  the  arm 
be  moved  forward  or  backward,  the  great  tuberosity  of  the  humerus  rubs  against  the 
coraco-acromial  arch,  and  forms  with  it  a  sort  of  supplementary  articulation,  lubricated 
by  the  bursa  situated  between  the  coraco-acromion  vault  and  this  great  trochanter.^ 
The  movement  of  abduction  may  be  carried  so  far  as  to  allow  the  arm  to  touch  the  head 
without  dislocation ;  for  the  capsular  ligament  is  sufficiently  loose,  especially  below,  to 
receive  almost  the  whole  head  of  the  bone  without  being  torn.  It  should  be  remarked, 
that  during  abduction  the  scapula  is  fixed,  which  explains  the  frequency  of  luxations  of 
the  humerus  downward. 

Adduction  is  limited  by  the  arm  meeting  with  the  thorax.  When  it  is  combined  with 
the  forward  motion,  the  upper  and  back  part  of  the  capsule,  and  the  muscles  which  cover 
it,  are  considerably  stretched.  The  scapula  does  not  participate  in  this  movement,  du- 
ring which  luxation  can  be  occasioned  only  by  a  very  strong  impulse  on  the  arm  upward 
and  backward. 

Circumduction  is  nothing  more  than  the  transition  of  the  humerus  from  one  to  another 
of  these  motions.  The  cone  which  it  describes  is  much  more  extensive  in  front  than 
behind,  a  circumstance  tending  greatly  to  facilitate  the  prehension  of  external  objects, 
which  is  the  chief  purpose  of  the  upper  extremities.  This  predominance  of  the  forward 
motions  has  been  already  noticed  in  the  sterno-clavicular  articulation,  and  will  be  found 
also  in  many  others. 

*  [This  is  the  ligamentum  proprium  anterius  of  authors  ;  but  the  author  has  taken  no  notice  of  another  liga- 
ment proper  to  the  scapula,  viz.,  the  ligamentvm  proprium  posterius,  a  thin  band  of  fibres  stretched  across  the 
notch  at  the  base  of  the  coracoid  process,  which  it  thus  converts  into  a  foramen.  The  supra-scapular  nerve 
generally  passes  below,  and  the  artery  above  it.] 

t  It  is  through  this  ingenious  and  simple  mechanism,  of  which  we  shall  soon  see  another  example  in  the 
articulation  of  the  femur  with  the  os  innominatnm,  that  the  movement  forward  of  the  humerus  maybe  carried 
far  enough  to  describe  a  demi-circle,  without  the  bone  being  displaced. 

X  If  theory  has  led  us  to  believe  that  the  coraco-acromion  vault  contributed  to  luxation,  by  offering  a  point 
of  support  to  the  lever  represented  by  the  humerus  abducted  from  the  body,  a  more  careful  observation,  on  the 
contrary,  has  demonstrated  that  this  supporting  of  the  humerus  was  impossible,  as  the  anterior  border  of  the 
coraco-acromion  ligament  is  alone  pressing  against  the  humerus  in  the  forcible  abduction,  and  luxation  is  al- 
ways produced  in  a  middle  abduction  of  the  urni. 


ARTICULATIONS    OF    THE    ELBOW. 


141 


Fig.n. 


Fig.  72. 


Rotation. — In  this  movement  the  humerus  does  not  turn  upon  its  own,  but  upon  an 
imaginary  axis,  directed  from  the  head  of  the  humerus  to  the  epi-trochlea,  parallel  to  the 
bone.  The  manner  in  which  the  rotatory  muscles  embrace  the  head  of  the  humerus  is 
highly  favourable  to  this  motion,  by  compensating  for  the  shortness  of  the  neck,  which 
serves  as  a  lever  for  the  rotatory  movements. 

The  Humero-cubital  Articulation,  or  Elbow-joint  {figs.  71  and  72). 

Preparation. — 1.  Remove  carefully  the  brachialis  anticus  muscle  ;  2.  Detach  the  ten- 
don of  the  triceps  from  above  downward,  without  opening  the  synovial  capsule  ;  3.  Re- 
move the  muscles  which  are  attached  to  the  internal  and  external  tuberosities,  keeping 
in  mind  that  the  lateral  ligaments  are  intimately  connected  with  the  tendons  of  these 
muscles.     This  articulation  belongs  to  the  class  of  trochlear  joints  (angular  ginglymi). 

Articular  Surfaces. — On  the  humerus  we  find,  1.  An  almost  perfect  trochlea  or  puUey 
presenting  two  edges,  of  which  the  internal  is  the  more 
prominent,  so  that,  when  the  end  of  the  bone  rests  upon 
a  horizontal  plane,  its  shaft  is  directed  very  obliquely 
from  above  downward  and  inward ;  2.  The  small  head, 
or  articidar  condyle,  separated  from  the  trochlea  by  a 
furrow,  which  is  also  articular  ;  3.  Two  cavities,  a  pos- 
terior, which  is  very  deep,  and  is  intended  to  receive 
the  olecranon  process,  and  an  anterior,  which  is  shal- 
lower, and  receives  the  coronoid. 

The  articular  surfaces  of  the  forearm  are,  1.  The 
greater  sigmoid  cavity  of  the  ulna,  which  exactly  em- 
braces the  trochlea  ;*  2.  The  glenoid  cavity  of  the  ra- 
dius, which  receives  the  small  head  of  the  humerus. 

The  means  of  union  consist  of  four  ligaments,  two 
lateral,  an  anterior,  and  a  posterior.  1.  The  external 
lateral  ligament  (a,  Jigs.  71,  72)  is  blended  with  the  ten- 
don of  the  supinator  brevis  ;  it  is  of  a  triangular  form, 
and  stretches  from  the  external  tuberosity  of  the  hu- 
merus to  the  annular  ligament,  with  which  it  becomes 
continuous,  and  which  seems  to  be  in  part  formed  by 
it.  Some  fibres  of  this  ligament  are  also  inserted  into 
the  outer  part  of  the  sigmoid  cavity  of  the  ulna.  This 
connexion  of  the  lateral  with  the  annular  ligament  is 
of  great  importance  with  reference  to  the  production 
of  luxations  of  the  upper  end  of  the  radius,  t 

2.  The  internal  lateral  ligaments  are  two  in  number ; 
one  internal,  properly  so  called,  or  humero-cormioidian ; 
the  other  internal  and  posterior,  humero-olecranian. 

The  former,  or  humero-coronoidian,  which  is  partly 
confounded  with  the  aponeurotic  tendon  of  the  superficial  flexor  muscle  of  the  fingers, 
is  a  thick,  rounded  bundle,  which  arises  below  the  internal  tuberosity  of  the  humerus, 
and  is  inserted  into  the  whole  internal  side  of  the  coracoid  process,  and  more  especially 
in  its  tubercle. 

The  second,  or  humero-olecranian,  which  might  be  described  as  a  posterior  ligament 
of  the  articulation,  is  thin  and  radiating ;  it  arises  from  the  posterior  portion  of  the  epi- 
trochlea,  and  irradiates  to  be  inserted  into  the  whole  extent  of  the  internal  border  of  the 
olecranon ;  the  inferior  bundles  are  the  strongest,  and  come  in  part  from  the  humero- 
coronoidian  ligament.  The  superior  bundles  are  thin  and  slender,  and  reach  beyond  the 
olecranon,  in  order  to  expand  over  the  synovial  membrane. 

3.  The  anterior  ligament  (c)  is  a  very  thin  layer,  in  which,  however,  three  orders  of 
fibres  can  be  recognised.  The  first,  directed  vertically,  fonn  a  bundle  which  extends 
from  the  upper  part  of  the  coronoid  cavity  to  the  lower  part  of  the  coronoid  process  ;  the 
second  are  transverse,  and  intersect  the  first  at  right  angles  ;  and,  lastly,  the  third  are 
obliquely  directed  downward  and  outward  to  the  annular  ligament,  t  We  shall  see, 
hereafter,  that  the  brachialis  anticus  renders  an  anterior  resisting  ligament  entirely  use- 
less ;  moreover,  the  most  inferior  and  deepest  fibres  of  this  muscle  are  directly  inserted 
in  this  anterior  hgament. 

*  Tbere  is  here,  indeed,  a  hinge  :  it  is  the  most  remarkable  example  of  a  hin?e  in  the  system  ;  it  is  the 
most  perfect  angular  ginglymoid.  The  two  articular  surfaces  present  a  sinuous  surface,  wliich  is  alternately 
concave  and  convex,  a  sort  of  catching  which  is  seen  nowhere  else. 

t  These  relations  between  the  annular  ligament  and  the  external  lateral  ligament  are  so  intimate  that  these 
two  ligaments  are  seldom  torn  independently  of  each  other  ;  hence  the  consecutive  dislocation  "f  the  radius 
.pon  the  cubitus  in  the  luxations  of  the  elbow  ;  hence,  also,  the  luxations  of  the  radius  upon  the  humerus, 
the  ulna  remaining  in  its  place.  (See  an  example  of  the  luxation  backward  of  the  radius  upon  the  humerus, 
the  ulna  remaining  in  its  place,  Anat.  Pathol.,  with  plates,  8th  number.) 

t  It  should  be  remarked,  that  none  of  these  ligaments  of  the  elbow-joint  are  attached  directly  to  the  radius, 
but  that  the  fibres  which  are- directed  towards  this  bone  join  the  annular  ligament.  This  arrangement  allows 
the  radius  to  rotate  with  perfect  freedom  within  its  ring,  which  would  have  been  impossible  had  the  fibr>^ 
been  directly  inserted  into  the  bone. 


142  ARTHROLOGY. 

4.  The  posterior  ligament  {d,fig.  72).  The  place  of  the  posterior  Hgament  is  occupied 
by  the  olecranon  and  the  tendon  of  the  triceps.  There  are  some  fibres,  however,  which 
sxtend  from  the  external  to  the  internal  tuberosity  of  the  humerus,  which  are  in  relation 
with  the  synovial  membrane  in  front,  and  the  tendon  of  the  triceps  behind.  The  princi- 
pal posterior  ligamentous  fibres  are  those  which  seem  to  arise  from  the  humero-olecra- 
nian  hgament. 

The  synovial  membrane  covers  the  posterior  surface  of  the  anterior  ligament ;  from 
this  it  is  reflected  upon  the  coronoid  cavity,  covers  the  olecranon  cavity  behind,  and  is 
prolonged  a  little  between  the  tendon  of  the  triceps  and  the  back  of  the  humerus.  In 
this  place  it  is  widest  and  most  loose.  Below,  it  forms  a  prolongation,  which  extends 
into  the  radio-cubital  articulation,  covering  the  whole  inner  surface  of  the  annular  liga- 
ment, and  forming  a  circular  cul-de-sac  below  it,  which  prevents  the  effusion  of  the  sy- 
novia.* There  is  some  synovial  adipose  tissue  round  the  points  of  reflection,  and  also 
at  the  margin  of  the  coronoid  and  olecranon  cavities. 

Mechanism  of  the  Humero-cuhital  Articulation. 
Extension  and  flexion,  the  only  motions  performed  by  this  joint,  are  executed  by  it  with 
remarkable  precision  and  rapidity.  The  precision  of  these  movements  depends,  1 .  Upon 
the  exact  fitting  of  the  articular  surfaces  ;  2.  Upon  the  great  extent  of  the  transverse  di- 
ameter, round  which  the  movements  of  flexion  and  extension  are  performed  as  round  an 
axis ;  3.  Upon  the  shortness  of  the  antero-posterior  diameter  of  the  inferior  extremity  of 
the  humerus,  and,  consequently,  on  the  smallness  of  the  circle  to  which  the  curve  of  the 
humeral  trochlea  belongs. 

1.  Flexion. — In  this  motion,  which  is  very  extensive,  the  radius  and  ulna  move  as  a  sin- 
gle bone  from  behind  forward,  on  the  small  head  and  trochlea  of  the  humerus.  It  should 
be  observed  that,  in  this  movement,  the  obliquity  of  the  trochlea  from  behind  forward,  and 
from  without  inward,  throws  the  forearm,  when  bent,  in  front  of  the  thorax,  and  the  hand 
in  front  of  the  mouth.  This  motion  is  limited  by  the  meeting  of  the  coronoid  process 
with  the  coronoid  cavity.  When  this  motion  is  carried  to  the  greatest  extent,  the  upper 
end  of  the  olecranon  descends  to  the  level  of  the  lowest  part  of  the  trochlea,  and  is,  con- 
sequently, below  the  line  which  passes  through  the  two  tuberosities,  or  condyles,  of  the 
humerus.  In  this  motion,  the  back  part  of  the  trochlea  and  the  olecranal  fossa  are  cov- 
ered only  by  the  tendon  of  the  triceps,  so  that  instruments  can  readily  enter  the  joint  at 
this  place.  The  flexion  of  the  elbow,  which  constitutes  a  fundamental  movement  in  pre- 
hension of  bodies,  may  be  carried  as  far  as  possible,  even  so  far  as  to  cause  the  forearm 
to  meet  the  arm,  without  any  risk  of  luxation,  as  any  sort  of  dislocation  here  is  impossi 
ble,  however  extensive  this  movement  may  be. 

2.  Extension. — In  this  movement,  the  radius  and  ulna  roll  backward  upon  the  humerus. 
This  motion  can  only  be  carried  so  far  that  the  forearm  and  the  arm  form  a  right  line, 
for  then  the  upper  part  of  the  olecranon  comes  in  contact  with  the  bottom  of  the  olecra 
nal  fossa.  The  anterior  ligament  and  the  anterior  and  middle  bundles  of  the  internal  lat- 
eral hgament  are  put  on  the  stretch,  and  thus  concur  in  limiting  the  movement  of  exten- 
sion, which  is  already  limited  by  the  olecranon  coming  in  contact  with  the  bottom  of  the 
olecranon  cavity.  There  is  no  appreciable  lateral  motion  of  this  joint,  the  exact  fitting 
of  the  articular  surfaces  effectually  preventing  it.+ 

The  Radio-cubital  Articulations  {figs.  71  to  75). 
In  these  articulations,  the  radius  and  the  ulna  are  united,  1.  By  their  upper  ends  {supe- 
rior radio-cubital  articulation) ;  2.  By  their  lower  ends  {inferior  radio-cubital  articulation) ; 
3.  By  the  interosseous  ligament  through  a  great  part  of  their  extent. 

Superior  Radio-cubital  Articulation. 

Preparation. — Remove  with  care  the  anconeus  and  the  supinator  brevis,  and  separate 
the  forearm  from  the  arm. 

The  articular  surfaces  are  the  edge  of  the  head  of  the  radius,  which  is  of  unequal  height 
in  different  parts,  and  the  lesser  sigmoid  cavity  of  the  ulna,  which  is  oblong  from  before 
backward,  broader  in  the  middle  than  at  the  ends,  and  which  forms  the  bony  portion  of 
the  osteo-fibrous  ring  in  which  the  head  of  the  radius  rolls. 

The  means  of  union  consist  of  the  annular  ligament  of  the  radius  {e,  figs.  71  and  72) 

*  [According  to  the  common  opinion,  the  articular  surfaces  of  the  radius  and  ulna  are,  of  course,  also  cov- 
ered by  the  synovial  membrane.] 

t  A  glance  at  the  articulation  of  the  elbow,  surrounded  by  its  ligaments,  is  sufficient  to  convince  us  of  the 
facility  with  which  the  dislocation  of  the  humerus  forward  takes  place,  favoured  as  it  is  by  the  smallness  of 
the  antero-posterior  diameter  of  the  articulation,  and  by  the  deficiency  in  the  resistance  of  the  anterior  liga- 
ment. This  dislocation  is,  next  to  that  of  the  humerus,  the  most  frequent,  notwithstanding  the  resistance  of 
the  brachialis  anticus,  which,  being  an  active  ligament,  supports  the  anterior  portion  of  the  articulation,  with 
which  it  is  so  closely  identified,  that,  in  this  dislocation,  it  is  always  torn,  at  least  incompletely.  This  dislo- 
cation forward  is,  moreover,  favoured  in  the  movement  of  extension  by  the  point  of  the  olecranon  meeting  the 
bottom  of  the  olecranon  cavity  of  the  humerus.  In  a  fall  upon  the  wrist,  the  forearm  being  extended,  the  hu- 
merus becomes  a  lever  of  the  first  kind,  whose  point  of  support  is  represented  by  the- olecranon  cavity  of  the 
humerus  strongly  pressed  against  by  the  point  of  the  olecranon  ;  the  lever  of  power  is  represented  by  the  whole 
length  of  the  humerus  ;  the  lever  of  resistance,  by  the  short  portion  of  the  humerus  below  the  olecranon  cavity 


RADIO-CUBITAL    ARTICULATIONS.  143 

This  ligament  is  a  band  forming  three  fourths  of  a  ring,  which  is  completed  by  the  lesser 
sigmoid  cavity  of  the  ulna  ;  it  is  attached,  by  its  two  ends,  to  the  fore  and  back  part  of 
this  cavity.  Its  internal  surface,  which  is  smooth  and  shining  like  mother-of-pearl,  is  in 
contact  with  the  articular  border  of  the  head  of  the  radius.  The  external  lateral  ligament 
is  attached  to  its  outer  surface,  and  evidently  becomes  continuous  with  its  posterior  half. 
This  arrangement  has  doubtless  given  rise  to  the  assertion,  that  the  external  lateral  lig- 
ament is  attached  to  the  ulna.  Those  fibres  of  the  anterior  ligament  which  are  directed 
obliquely  downward  and  outward  are  also  inserted  into  the  annular  ligament.  All  these 
ligamentous  attachments  retain  the  annular  ligament  in  its  proper  position ;  when  they 
are  divided,  it  is  manifestly  retracted  towards  the  neck  of  the  radius,  and  exposes  the  ar- 
ticular edge  of  the  bone.  The  breadth  of  the  annular  ligament  is  from  three  to  four  lines, 
and  its  upper  circumference  is  wider  than  the  lower,  which  construction  tends  to  main- 
tain the  head  of  the  radius  in  its  situation  more  accurately.  With  regard  to  its  structure, 
I  would  observe,  that  it  is  much  thicker  behind,  where  it  receives  the  insertion  of  the  ex- 
ternal lateral  ligament,  than  in  front,  where  it  may  be  much  more  easily  ruptured  ;  and 
I  am  persuaded  that,  in  luxation  of  the  elbow,  it  is  not  the  external  lateral  ligament 
which  is  most  commonly  torn,  but  rather  the  anterior  portion  of  the  annular. 

The  synovial  capsule  is  a  sort  of  diverticulum  from  that  of  the  elbow-joint,  which  is 
prolonged  upon  the  inner  surface  of  the  annular  ligament,  and  is  reflected  upward  from 
its  lower  margin,  so  as  to  form  a  sort  of  cul-de-sac  below  it. 

Inferior  Radio-cubital  Articulation. 

Preparation. — 1.  Remove  the  muscles  on  both  aspects  of  the  forearm.  2.  Separate  the 
hand  from  the  forearm  so  as  to  expose  the  lower  surface  of  the  triangular  ligament,  or 
fibro-cartilage.  3.  In  order  to  examine  the  interior  of  the  joint,  saw  through  the  middle 
of  the  forearm ;  divide  the  anterior  and  posterior  ligaments  ;  separate  the  two  bones  of 
the  forearm  ;  cut  through  the  triangular  ligament  at  its  insertion  into  the  ulna. 

The  articular  surfaces  are  a  small  sigmoid  cavity  on  the  radius,  analogous  to  that  which 
we  have  described  at  the  upper  end  of  the  ulna,  and  the  external  two  thirds  of  the  cir- 
cumference of  the  head  of  the  ulna.  This  articulation,  therefore,  is  precisely  the  re- 
verse of  the  upper,  since  in  this  the  ulna  furnishes  tl\e  head,  and  the  radius  the  sigmoid 
cavity,  while  a  precisely  opposite  arrangement  obtains  in  the  upper  joint. 

The  means  of  union  are,  1.  Some  fibres  stretched  in  front  and  behind  the  joint,  and  call- 
ed anterior  (/,  Jigs.  71  and  75)  and  posterior  (ff,  Jigs.  72  and  74)  ligaments.  They  form  a 
very  imperfect  annular  ligament.  They  extend  from  the  anterior  and  posterior  margins 
of  the  sigmoid  cavity  of  the  radius  to  the  anterior  and  posterior  surfaces  of  the  little  head 
of  the  ulna,  in  the  neighbourhood  of  its  styloid  process. 

2.  The  triangular  ligament,  or,  rather,  cartilage*  {i,Jigs.  7i  and  73).  This  is  a  triangu- 
lar lamina  of  cartilage,  the  apex  of  which  is  fixed  into  the  angle  formed  by  the  head  and 
styloid  process  of  the  ulna,  and  its  base  into  the  lower  edge  of  the  sigmoid  cavity  of  the 
radius.  It  is  thin  at  the  base  and  the  centre,  and  thick  at  the  apex  and  the  circumfer- 
ence. It  concurs  in  maintaining  the  union  of  the  radius  and  ulna,  and  performs  the  office 
of  those  inter-articular  cartilages  which  we  have  noticed  as  peculiar  to  such  joints  as  are 
most  exposed  to  shocks  and  friction  ;  and,  above  all,  it  restores  the  level  of  the  inferior 
radio-cubital  surface  by  filling  up  the  vacancy  caused  by  the  projection  of  the  radius  be- 
low the  ulna. 

There  is  a  separate  synovial  membrane  for  this  joint  (see  above,  i.  Jig.  75),  (often  called 
membrana  sacciformis).  It  covers  the  upper  surface  of  the  triangular  ligament,  and  the 
sort  of  incomplete  ring  which  circumscribes  the  head  of  the  ulna.  It  forms  very  loose 
folds  at  the  places  of  reflection,  which  admit  of  very  extensive  rotation.  This  synovial 
membrane  is  common  to  the  articulation  of  the  ulna  with  the  radius,  and  to  the  articula- 
tion of  the  ulna  with  the  inter-articular  cartilage  ;  it  is  entirely  independent  of  the  syno- 
\ial  membrane  of  the  wrist-joint. 

Middle  Radio-cubital  Articulation,  or  Interosseous  Ligament. 
The  interosseous  ligament  {I,  figs.  71,  72),  improperly  so  called,  is  an  aponeurosis  which 
occupies  the  interval  between  the  radius  and  ulna,  and  which  appears  to  serve  princi- 
pally for  the  insertion  of  muscles.  It  is  broader  in  the  middle  than  at  the  ends,  and  does 
not  reach  the  extremities  of  the  interosseous  space,  for  there  is  an  interval  above  and 
below,  which  serves  the  purpose  of  giving  passage  to  nerves  and  vessels,  and  also  per- 
mits more  free  motion  between  the  two  bones.  The  fibres  which  compose  it  are  direct- 
ed obhquely  downward  and  inward,  i.  e.,  from  the  radius  to  the  ulna.  We  generally  ob- 
serve on  its  anterior  aspect  several  bundles  running  downward  and  outward ;  the  supe- 

*  This  is  the  only  example  in  the  system  of  an  inter-articulary  cartilage  serving  as  a  means  of  union  be- 
tween the  bones.  Can  its  principal  use  be  to  prevent  the  dislocation  of  the  ulna  in  the  movements  of  rotation  1 
The  following  experiment  will  show  that  this  cartilage  does  not  oppose  the  forcible  movements  of  pronation 
and  supination :  Saw  the  bones  of  the  forearm  at  their  middle  line,  separate  the  forearm  from  the  wrist,  ro- 
tate with  the  utmost  force  the  radius  upon  the  ulna,  and  it  will  be  sedn  that,  during  these  movements,  the  in- 
ter-articular cartilage  remains  unstrained  in  all  its  points.  This  cartilage  is  attached  to  the  groove  of  the  sty 
loid  process  of  the  ulna  by  fibrous  tissue  ;  what  it  called  the  summit  of  the  triangular  cartilage  is,  therefore 
Dothing  else  than  a  very  short  and  strong  little  ligament,  by  which  the  cartilage  is  attached  to  the  ulna. 


144  ARTHEOLOGY. 

rior  and  the  strongest  of  these  is  called  the  round  ligament,  or  the  ligamentous  cord  of 
Weitbrecht  (m,  Jig.  71).  It  extends  obliquely  downward  and  outward,  from  the  outside 
of  the  coronoid  process  of  the  ulna  to  the  lower  part  of  the  bicipital  tuberosity  of  the  ra- 
dius. Its  direction  is,  therefore,  precisely  the  inverse  of  that  of  the  fibres  of  the  inter- 
osseous ligament. 

Mechanism  of  the  Radio-cubital  Articulations. 
These  articulations,  like  all  trochlear  joints,  only  admit  of  one  kind  of  motion,  viz., 
rotation,  which  is  here  called  by  a  peculiar  name.     Rotation  forward  is  denominated 
■pronation. ;  rotation  backward  is  called  sjipination.     We  must  examine  these  in  both  the 
upper  and  the  lower  radio-cubital  articulations. 

Mechanism  of  the  Superior  Radio-cubital  Articulations. 

Pronation. — In  this  movement,  the  inner  part  of  the  head  of  the  radius  rolls  backward 
upon  the  lesser  sigmoid  cavity  of  the  ulna,  and  may  be  carried  so  far  that  the  radius  may 
describe  half  a  circle  upon  its  axis.  Notwithstanding  the  obstacles  to  displacement  re- 
sulting from  the  strength  of  the  back  part  of  the  annular  ligaments,  and  the  presence  of 
the  two  little  hooks,  one  in  front  and  the  other  behind  the  lesser  sigmoid  cavity  of  the 
ulna,  and,  lastly,  notwithstanding  the  advantage  produced  by  the  reception  of  the  small 
head  of  the  humerus  in  the  cup-like  cavity  of  the  upper  end  of  the  radius,  in  violent  pro- 
nation the  head  of  the  radius  is  frequently  luxated  backward.  Perhaps  no  dislocation  is 
more  common  in  infancy  than  the  incomplete  luxation  backward  of  the  upper  end  of  the 
radius,  on  account  of  the  greater  looseness  of  the  annular  ligament,  and  the  less  com- 
plete reception  of  the  small  head  of  the  humerus  in  the  cupula  of  the  radius.  The  cause 
occasioning  this  displacement  is  forced  pronation,  so  frequent  when  infants  are  held  by 
the  hand,  in  attempting  to  save  them  from  falling. 

In  supination,  the  head  of  the  radius  turns  upon  its  axis  in  a  different  direction,  i.  e., 
its  inner  part  ghdes  forward  upon  the  lesser  sigmoid  cavity  of  the  ulna.  If  it  be  carried 
too  far,  dislocation  forward  may  be  the  consequence.* 

Mechanism  of  the  Inferior  Radio-cubital  Articulations. 

The  movements  of  pronation  and  supination,  at  the  lower  radio-cubital  articulation, 
are  produced  by  a  mechanism  which  is  precisely  the  inverse  of  the  former  ;  for  the  ra- 
dius, instead  of  rotating  upon  its  own  axis,  turns  round  the  head  of  the  ulna  by  a  move- 
ment of  circumduction.  This  difference  results  partly  from  the  curvature  of  the  radius, 
and  partly  from  the  great  transverse  diameter  of  its  lower  end,  which  forms  the  radius 
of  the  arc  of  the  circle  which  it  describes  round  the  ulna.  In  pronation,  the  little  sig- 
moid cavity  roUs  forward  on  the  articular  edge  of  the  head  of  the  ulna ;  in  supination,  it 
glides  in  the  opposite  direction,  that  is,  backward.  We  see,  then,  that  in  the  lower  ar- 
ticulation, a  concave  surface  moves  upon  a  convex,  while  the  contrary  takes  place  at 
the  upper.  • 

Does  the  inter-articular  cartilage  limit  these  motions,  as  it  has  been  asserted  1  The 
experiment  which  I  have  indicated  above  shows  that  this  cartilage  is  in  the  same  con- 
ditions in  regard  to  the  articular  surfaces,  both  in  pronation  and  supination,  and  that  the 
small  ligament  which  attaches  it  to  the  groove  of  the  styloid  process  of  the  ulna,  expe- 
riences neither  tension  nor  relaxation.  The  anterior  and  posterior  ligaments  alone  are 
able  to  limit  the  movements  of  rotation  by  their  resistance  ;  but,  in  forcible  pronation, 
these  may  be  broken,  and  the  head  of  the  ulna  dislocated  backward  ;  in  forcible  supina- 
tion, it  may  be  dislocated  forward.  It  should  be  remarked  that,  in  cases  of  luxation  of 
the  ulna,  the  head  of  this  bone  does  not  lacerate  the  capsule,  but  the  capsule  is  torn  upon 
it ;  for,  as  we  shall  afterward  see,  the  ulna  is  immovable  at  the  cubito-carpal  joint,  and 
takes  no  share  in  the  partial  motions  of  the  forearm. 

Mechanism  of  the  Radio-cubital  Articulations,  considered  with  reference  to  the  Bodies  of  the 

two  Bones. 
In  the  movement  of  pronation,  the  radius  crosses  the  ulna  at  an  acute  angle,  so  that 
its  lower  part  is  carried  in  front  of  the  ulna,  while  the  upper  remains  on  the  outside. 
The  movement  of  supination  consists  in  the  return  of  the  radius  to  its  state  of  parallel- 
ism with  the  ulna.  In  pronation,  the  interosseous  ligament  is  relaxed  ;  in  supination,  it 
is  stretched  :  its  absence  at  the  upper  part  of  the  forearm,  where  its  place  is  supphed  by 
the  ligament  of  Weitbrecht,  allows  more  extensive  rotatory  movements,  t 

*  This  displacement  is  very  uncommon,  on  account  of  the  hook-like  projection  at  the  anterior  extremity  of 
the  sigmoid  cavity,  and  doubtless,  also,  because  forcible  supination  is  very  rjjre.  Professor  Dng^es  informs  me 
that  he  has  seen  an  instance  of  this  dislocation  of  the  radius,  and  proved  its  existence  by  inspection  after 
death.  I  have  myself  recMitly  met  with  a  case  of  an  incomplete  dislocation  forward  in  a  child  ;  a  slight  pres- 
sure from  before  backward  upon  the  superior  extremity  of  the  radius  was  sufficient  to  reduce  the  dislocation, 
which  took  place  on  a  sudden,  while  the  child  was  being  dressed. 

t  If  the  interosseous  ligament,  the  fibres  of  which  pass  downward  from  the  radius  to  the  ulna,  had  besn 
prolonged  to  the  upper  part  of  the  interosseous  space,  it  would  have  much  impeded  the  motions  of  supination, 
l)y  limiting  the  movements  of  the  bicipital  tuberosity,  into  which  one  of  the  supinator  muscles  of  the  forearm, 
viz.,  the  biceps,  is  inserted  ;  but  the  round  ligament  being  inserted  below  the  bicipital  tuberosity,  and  passing 
dojwQward  from  the  ulna  to  the  radius,  can  have  no  effect  in  limiting  the  extent  of  rotation 


RADIO-CARPAL    ARTICULATION.  145 

The  existence  of  the  interosseous  space  is  an  indispensable  condition  for  the  peiform- 
ance  of  pronation  and  supination ;  and,  therefore,  every  curative  plan  for  the  treatment 
of  fractures  of  the  forearm  which  does  not  provide  for  the  preservation  of  this  space 
should  at  once  be  rejected. 

In  the  explanation  we  have  given  of  the  mechanism  of  the  radio-cubital  articulations 
the  ulna  has  been  considered  as  an  immovable  axis,  round  which  the  radius  executes 
below  certain  movements  of  circumduction ;  but  many  authors  have  maintained  the 
opinion  that  the  ulna  also  takes  part  in  these  motions.  Without  discussing  the  different 
theories  which  have  been  successively  proposed  on  this  subject,  we  shall  mention  an 
experiment  which  is  at  once  decisive  of  the  question.  If  all  the  articulations  of  the  arm 
be  exposed  from  the  shoulder  to  the  hand,  and  the  humerus  be  immovably  fixed  in  a 
vice,  it  will  be  seen  that,  when  the  forearm  is  pronated  or  supinated,  the  radius  moves 
upon  the  ulna,  which  remains  altogether  imdisturbed ;  and,  also,  that  any  lateral  motion 
of  the  ulna  is  absolutely  impossible,  from  its  perfect  jointing  with  the  humerus  at  the 
elbow.  When  the  humerus  is  not  completely  fixed,  it  also  rotates  in  conjunction  with 
the  bones  of  the  forearm. 

Lastly,  it  should  be  observed  that,  when  the  radius  is  rotated  during  semiflexion  of 
the  forearm,  the  motion  is  accompanied  by  slight  degrees  of  flexion  and  extension  at  the 
elbow-joint. 

Radio-carpal  Articulation  {figs.  73  to  75). 

Preparation. — Divide  the  fibrous  sheaths  of  the  flexor  and  extensor  tendons,  and  care- 
fully remove  those  tendons  ;  bearing  in  mind  the  fact  that  the  fibrous  sheaths  closely  ad- 
here to  the  ligaments,  or,  rather,  are  identified  with  them,  and  may  be  considered  as  an 
appurtenance  of  the  ligamentous  apparatus  of  the  joint. 

This  articulation  belongs  to  the  class  of  condylarthroses. 

The  articular  surfaces  (fig.  73)  are  those  of  the  scaphoid,  the  semilunar,  and  the  cunei- 
form, which  together  form  a  condyle,  oblong  transversely,  and  covered  by  articular  car- 
tilages, which  are  prolonged  farther  on  the  posterior  than  on  the  anterior  aspect  of  the 
bones,  and  the  transversely  oblong  concave,  articular  surface,  formed  by  the  lower  ends 
of  the  radius  and  ulna.  The  radius,  which  forms  by  itself  two  thirds  of  the  surface,  cor- 
responds to  the  scaphoid  and  semilunar,  and  presents  an  antero-posterior  ridge,  and  a 
slight  contraction  from  before  backward,  opposite  the  interval  between  these  two  bones. 
The  ulna  corresponds  to  the  cuneiform  bone,  with  the  intervention  of  an  inter-articular 
cartilage,  viz.,  the  triangular  cartilage  already  described,  which  performs  the  part  both  of 
a  hgament  and  an  inter-articular  cartilage.  The  concave  surface  presented  by  the  lower 
part  of  the  forearm  is  completed  at  the  sides  by  the  styloid  processes  of  the  radius  and  ulna. 

Means  of  Union. — There  are  for  this  joint  an  external  lateral  hgament,  an  internal  lat- 
eral, two  anterior,  and  one  posterior  hgament. 

The  external  lateral  ligament  {a,  figs.  73,  74,  75)  stretches  from  the  summit,  and  forms 
the  neighbouring  parts  of  the  styloid  process  of  the  radius  to  the  outer  part  of  the  scapho- 
id, where  it  is  inserted  by  a  broad  attachment  immediately  on  the  outside  of  the  radial  ar- 
ticular surface  of  that  bone.  This  ligament,  which  is  not  very  thick,  is  continuous  with 
the  anterior  and  the  posterior  ligament,  without  any  line  of  demarcation  being  perceived. 

The  internal  lateral  ligament.  It  is  uncovered  immediately  after  the  tendinous  sheath 
of  the  extensor  carpi  ulnaris  has  been  divided.  It  is  lined  by  the  synovial  membrane  of 
this  sheath.  It  is  a  cylindrical  chord,  commencing  at  the  styloid  process,  of  which  it 
seems  to  be  a  continuation,  and  dividing  inferiorly  into  two  fasciculi,  one  of  which  is  at- 
tached to  the  pisiform,  the  other,  which  is  more  considerable,  to  the  posterior  surface  of 
the  cuneiform  bone.  This  chord  first  appears  very  thick  ;  but,  on  dividing  it,  it  is  seen 
perforated  by  a  cavity  communicating  inferiorly  with  the  radio-carpal  articulation,  and  its 
superior  extremity  is  not  attached  to  the  summit  of  the  styloid  process  of  the  ulna,  but  to 
the  middle  point  of  this  process,  in  the  form  of  a  demi-capsule.  The  summit  of  this  pro- 
cess is  articular,  and  surrounded  with  a  thick  layer  of  cartilage  ;  it  is  farther  contained 
in  the  synovial  membrane  of  the  wrist,  and  is  in  direct  relation  with  the  cuneiform  bone. 
The  styloid  process  of  the  ulna  is  therefore  the  only  portion  of  this  bone  which  enters  di- 
rectly into  the  wrist-joint. 

The  anterior  ligaments  are  two  in  number,  one  radial,  the  other  ulnar. 

The  radio-carpal  hgament  forms  a  broad  layer  resembling  mother-of-pearl,  which  ap- 
pears as  soon  as  the  flexor  tendons  have  been  removed.  It  is  composed  of  bundles,  which 
are  often  separated  by  adipose  cellular  tissue  and  vessels,  so  that  I  considered  it  neces- 
sary, in  the  former  edition  of  this  work,  to  describe  three  anterior  radial  bundles,  an  ex- 
ternal, a  middle,  and  an  internal ;  I  have  abandoned  this  distinction,  because  it  does  not 
appear  of  any  use.  This  ligament  arises  from  the  whole  breadth  of  the  anterior  border  of 
the  inferior  extremity  of  the  radius  around  the  articular  surface  ;  it  also  arises  from  the 
anterior  border  of  the  styloid  process  of  this  bone.  Hence  its  fibres  stretch  from  above 
downward,  and  from  without  inward,  approximating  to  a  horizontal  position,  in  proportion 
as  they  are  more  elevated.  The  most  external  fibres  go  to  the  os  unciforme  and  the  os 
magnum ;  those  which  come  next  are  inserted  into  the  scaphoid  bone  ;  others,  again,  into 

T 


146  ARTHEOLOGY. 

the  cuneiform  and  the  pisiform  bones.  The  most  elevated  fibres,  which  ire  the  most  in- 
ternal, seem  to  be  continuous  with  the  anterior  ligament  of  the  inferior  "adio-cubital  ar- 
ticulation. The  most  external  bundles  of  this  ligament  are  tl  e  thickest.  This  ligament 
is  composed  of  several  layers  of  fibres,  the  most  superficial  cf  which  are  the  longest. 

The  ulnar-carpal  ligament  has  probably  been  conjfounded  by  authors  with  the  internal 
lateral  Ugament ;  or  perhaps  it  may  have  escaped  their  notice  altogether,  on  account  of 
its  being  deeply  seated.  This  ligament  arises,  by  a  narrow  extremity,  from  the  groove 
which  separates  the  styloid  process  from  the  little  head  of  the  ulna,  in  front  of  the  small 
ligament  which  forms  the  summit  of  the  inter-articular  cartilage  ;  thence  it  goes  down- 
ward and  outward,  passes  under  a  few  fibres  of  the  anterior  radio-carpal  ligament,  and  ■ 
lost  by  irradiating.  The  horizontal  superior  fibres  describe  a  curve  beneath  the  head  o- 
the  idna,  and  are  inserted  into  the  anterior  border  of  the  radius,  where  they  are  confound- 
ed with  the  fibres  of  the  radio-carpal  ligament ;  the  inferior  fibres  descend  almost  verti- 
cally downward,  externally  to  the  pisiform  bone,  and  terminate  in  the  os  cuneiforme. 

The  posterior  ligament  cannot  possibly  be  separated  from  the  fibrous  sheath  of  the  ex- 
tensor and  radial  tendons,  with  which  it  is  continuous.  There  is  but  one  posterior  liga- 
ment ;  it  is  much  weaker  and  narrower  than  the  anterior  radio-carpal  ligament,  and 
stretches  obhquely  from  the  posterior  border  of  the  radius  to  the  posterior  faces  of  the 
cuneiform  and  the  semilunar  bones.  The  bundle  which  goes  to  the  cuneiform  is  the 
stronger.  This  ligament  covers  about  the  third  portion  of  the  joint,  while  the  radio-car- 
pal ligament  covers  the  whole  of  the  anterior  surface.  It  should  be  observed,  that  there 
is  a  marked  predominance  of  the  anterior  over  the  posterior  ligaments,  both  in  the  artic- 
ulation of  the  hand  with  the  forearm,  and  in  the  articulations  of  the  carpus. 

With  regard  to  the  anterior  and  posterior  ligaments  of  the  radio-carpal  articulation,  I 
shall  make  an  observation  which  may  be  of  some  interest :  it  is,  that  all  these  ligaments, 
with  the  exception  of  the  cubito-carpal,  come  from  the  radius,  and  closely  unite  the  inferior 
extremity  of  that  bone  to  the  first  range  of  the  carpus,  and,  consequently,  to  the  hand. 

The  synovial  membrane  (see  Jig.  73)  is  loose  behind,  where  it  is  only  partially  covered 
by  the  ligaments  we  have  described  ;  throughout  the  whole  of  the  remaining  circumfer- 
ence of  the  joint  it  is  strengthened  by  scattered  ligamentous  fibres,  which  some  anato- 
mists have  described  as  a  capsular  ligament.  This  synovial  membrane  sometimes  com- 
municates with  that  of  the  lower  radio-cubital  articulation,  by  an  opening  at  the  place  o 
union  of  the  triangular  cartilage  with  the  lower  edge  of  the  sigmoid  cavity  of  the  radius. 
It  also  sometimes  communicates  with  the  general  synovial  membrane  of  the  carpus,  by 
the  interosseous  spaces  which  separate  the  bones  of  the  first  carpal  row. 

Besides  the  means  of  union  which  we  have  described,  the  flexor  tendons  in  front,  and  the 
extensor  tendons  behind,  should  be  noticed,  as  serving  to  increase  the  strength  of  the  joint. 

Mechanism  of  the  Radio-carpal  Articulation. 

This  articulation  belongs  to  the  condyloid  class,  and  has,  therefore,  four  motions,  viz., 
flexion,  extension,  abduction,  and  adduction,  and  by  passing  from  one  of  these  to  the 
other,  it  can  perform  circumduction. 

1.  Flexion. — In  this  motion,  the  condyle  formed  by  the  first  row  of  the  carpus  glides 
Ibackward  upon  the  lower  end  of  the  forearm.  The  posterior  ligaments  and  the  exten- 
:Sor  tendons  are  put  on  the  stretch.  When  the  movement  of  flexion  is  carried  too  far, 
luxation  may  take  place  by  laceration  of  the  posterior  ligament,  and  then  the  lower  end 
of  the  two  bones  of  the  forearm  pass  in  front  of  the  articular  surface  of  the  bones  of  the 
first  row  of  the  carpus.  The  possibility  of  dislocation  of  this  joint  has  been  doubted  ; 
but  I  have  seen  two  instances  of  this  kind  of  dislocation,  which  were  incontestable. 

2.  In  extension,  the  condyle  formed  by  the  carpus  roUs  forward  upon  the  lower  end  of 
the  forearm ;  and  as  the  articular  surface  of  the  carpus  reaches  farther  on  the  back  than 
in  .front,  it  follows  that  extension  may  be  carried  farther  than  flexion:  it  is  limited  by 
the  strong  anterior  ligaments,  and  also  by  the  lateral  ligaments,  which,  as  is  generally 
observed,  are  attached  nearer  to  the  side-  of  flexion  than  to  that  of  extension. 

It  should  also  be  remarked,  that  extension  is  the  easiest  motion  of  the  hand  upon  the 
forearm :  this  may  be  readily  understood  from  the  great  power  which  the  hand  possess- 
es when  it  forms  a  right  angle  behind  with  the  forearm.* 

3.  In  abduction,  the  condyle  formed  by  the  carpus  rolls  in  the  direction  of  its  length, 
t.  c,  transversely  and  from  without  inward,  while  the  radial  edge  of  the  hand  is  inchned 
towards  the  radial  edge  of  the  forearm  :  this  motion  is  limited  by  the  mutual  meeting  of 
the  styloid  process  of  the  radius,  and  the  external  process  of  the  scaphoid. 

4.  In  adduction,  the  ulnar  edge  of  the  hand  is  bent  towards  the  ulnar  edge  of  the  fore- 
;  arm ;  the  motion  is  limited  by  the  meeting  of  the  summit  of  the  styloid  process  of  the 

ulna  and  the  cuneiform  bone,  and  also  by  the  tension  of  the  external  lateral  ligamsnt. 
It  may  be  easily  conceived,  that  in  the  lateral  movements,  which  are  performed  in 

*  We  should  observe  that  it  is  almost  impossible  to  separate  the  mechanism  of  the  carpal  articulations 
irom  that  of  the  radio-carpal  joint ;  the  latter  is  noticed  here  by  itself  only  in  order  to  conform  with  the  ana 
toicical  divisions. 


ARTICULATIONS  OF  THE  CARPUS.  147 

the  direction  of  the  long  diameter  of  the  articular  surfaces,  dislocation  must  be  very  dif 
ficult,  and  that,  when  it  does  occur,  it  must  be  incomplete. 

The  movement  of  circumduction  is  nothing  more  than  a  succession  of  the  different  m» 
tions  which  have  been  already  pointed  out.  The  hand  describes  a  cone,  of  greater  ex 
tent  behind,  that  is,  in  the  direction  of  extension,  than  in  front,  or  in  the  direction  o» 
flexion.     It  is  also  still  more  restricted  in  adduction  and  abduction. 

Articulations  of  the  Carpus  (figs.  73  to  75). 
These  articulations  comprise,  1.  The  articulations  of  the  bones  of  each  row  together 
and,  2.  The  articulations  of  the  two  rows. 

Articulations  of  the  Bones  of  each  Row. 

Preparation. — 1.  Remove  the  extensor  and  the  flexor  tendons  ;  2.  Separate  the  hand 
from  the  forearm,  then  the  first  row  from  the  second,  and,  lastly,  the  bones  of  both  rows 
from  each  other,  examining  their  means  of  union  before  completing  the  separation. 

Articular  Surfaces. — The  articulations  of  the  bones  of  each  row  are  amphi-arthroses, 
and,  consequently,  present  one  part  continuous  and  another  contiguous.  The  bones  of 
the  first  row  correspond  to  each  other  by  oblique  surfaces,  those  of  the  second  row  by 
vertical  and  more  extensive  surfaces. 

Means  of  Union. — Two  classes  of  ligaments  belong  to  these  joints  :  the  one  is  extend- 
ed between  the  corresponding  surfaces,  the  interosseous  ligaments;  the  other  set  are 
peripheral,  and  are  divided  into  palmar  and  dorsal. 

The  palmar  and  dorsal  ligaments  are  fibrous  bundles,  stretched  transversely  or  oblique- 
ly from  each  of  the  bones  of  the  carpus  to  those  which  are  contiguous  to  it.  The  dorsal 
are  much  thinner  than  the  palmar. 

The  interosseous  ligaments  are  not  disposed  in  an  exactly  similar  manner  in  the  two 
rows,  and  we  shall,  therefore,  examine  them  separate-  ^    73 

ly.  1 .  The  interosseous  Ugaments  of  the  first  row  (e  e, 
fig.  73)  occupy  only  the  upper  part  of  the  corresponding  u 
facettes  ;  they  are  nothing  more  than  small  fibrous  bun-  \' 
dies,  one  extending  from  the  scaphoid  (1)  to  the  semi- 
lunar (2) ;  the  other  from  the  semilunar  to  the  cunei- 
form (3) ;  they  are  sometimes  partially  interrupted,  and 
present  openings,  which  establish  a  communication  be- 
tween the  general  synovial  membrane  of  the  carpus 
and  that  of  the  radio-carpal  articulation.  These  inter- 
osseous ligaments  are  reddish,  scarcely  fascicidated, 
very  loose,  so  as  to  admit  of  pretty  extensive  gliding 
motions.  2.  The  interosseous  ligaments  {d  d  d)  of  the 
second  row  are  much  thicker  than  those  of  the  first ; 
the  whole  non-articular  portion  of  the  corresponding 
facettes  gives  insertion  to  these  Ugaments,  which  are 
very  compact,  and  of  a  much  more  dry  and  close  tex- 
ture than  the  reddish  tissue  connecting  together  the  bones  of  the  fii-st  row.  It  follows, 
therefore,  that  the  bones  of  the  second  row  are  more  firmly  united  than  those  of  the  first, 
whose  interosseous  ligaments  are  loose,  and  permit  a  certain  degree  of  mobility.  The 
articulation  of  the  pisiform  bone  with  the  cuneiform  merits  a  special  description. 

Articulation  of  the  Pisiform  and  Cuneiform  Bodies. 

For  this  articulation,  the  pisiform  bone  presents  a  single  articular  surface,  which 
unites  with  the  auterior  facette  of  the  cuneiform  bone.  There  are  four  ligaments  in 
this  little  joint,  which  is  nothing  else  but  a  loose  arthrodia  :  1.  Two  inferior  {e,fig.  75), 
which  are  very  strong,  viz.,  an  external,  stretched  obliquely  from  the  pisiform  to  the 
hook-like  process  of  the  unciform  bone  ;  and  an  internal,  vertical,  which  is  inserted  into 
the  upper  end  of  the  fifth  metacarpal  bone.  These  two  ligaments  appear  partly  to  re- 
sult from  the  bifurcation  of  the  tendon  of  the  flexor  carpi  ulnaris,  this  tendon  being  in 
the  place  of  the  superior  ligament,  which  is  wanting.  The  internal  lateral  ligament  of 
the  radio-carpal  articulation  may  also  be  considered  as  entering  into  the  structure  of  the 
superior  ligament.  2.  An  anterior  and  a  posterior  ligament,  thin  and  radiating,  which 
strengthen  the  synovial  capsule  in  front  and  behind. 

The  synovial  capsule  is,  most  commonly,  a  small  isolated  pouch  ;  and  sometimes  it  is 
a  prolongation  of  the  radio-carpal  synovial  membrane.  This  capsule  is  ver>'  loose,  and 
the  ligaments  are  not  very  tight ;  hence  the  great  mobility  of  the  articulation. 

Articulation  of  the  two  Rows  of  Carpus  together. 

The  articulation  of  the  two  rows  of  the  carpus  together  presents  an  enarthrosis  in  the 
middle,  and  an  arthrodia  on  each  side. 

The  articular  surfaces  consist  of  a  head  or  spherical  eminence  received  into  a  cavity, 
constituting  the  enarthrosis,  and  of  plane  surfaces  on  the  inside  and  the  outside,  whick 
form  a  double  arthrodia.     The  head  is  formed  by  the  os  magnum  (6<fig  ^^^  ^"^  ^■he  su- 


148  ARTHROLOGY. 

perior  process  of  the  os  unciforme  (7) :  the  cavity  is  constituted  by  tne  inferior  surfaces 
of  the  scaphoid  (1),  the  semilunar  (2),  and  the  cuneiform  (3)  bones.  This  cavity,  which 
is  deeply  notched  in  front  and  behind,  is  completed  in  these  situations  by  two  ligaments, 
an  anterior  and  a  posterior,  which  might  be  called  glenoid  ligaments,  considering  their  po- 
sition on  the  edge  of  a  cavity,  and  their  use  in  increasing  its  depth. 

The  posterior  glenoid  ligament  is  composed  of  transverse  fibres,  which  are  inserted  into 
the  first  row,  closing  up  the  posterior  notch. 

The  anterior  glenoid  ligament,  much  stronger  than  the  other,  belongs  to  the  second 
row ;  it  is  confounded  with  the  anterior  ligaments  of  the  articulation,  between  the  two 
rows,  and  extends  transversely  from  the  os  unciforme  to  the  trapezium,  passing  in  front 
of  the  neck  and  the  head  of  the  os  magnum.  Besides  these  ligaments,  we  also  find,  1 
An  anterior  ligament  (i,  fig.  75),  which  is  very  thick,  and  stretches  from  the  anterior  sur- 
face of  the  OS  magnum,  by  diverging  rays,  to  those  three  bones  of  the  first  row  that  form 
the  enarthrodial  cavity,  in  which  the  head  of  the  os  magnum  is  received,  viz.,  the  sca- 
phoid, the  semilunar,  and  the  cuneiform.  2.  A  posterior  ligament  (i,  fig.  74),  which  con- 
sists merely  of  some  fibres  extending  obliquely  from  the  bones  of  the  first  row  to  those 
of  the  second. 

On  the  inside  and  the  outside  of  this  carpal  enarthrosis  we  find  an  arthrodia.  On  the 
tnside  is  the  articulation  of  the  cuneiform  (3,  fig.  73)  with  the  unciform  (7)  bone,  consti- 
tuted by  plane  surfaces,  and  strengthened  by  a  very  thin  posterior  ligament,  an  anterior 
ligament,  much  thicker  than  the  preceding,  and  an  internal  lateral  ligament  (c).  On  the 
outside  is  the  articulation  of  the  scaphoid  with  the  trapezium  and  the  trapezoid.  The  ar- 
ticular surface  of  the  scaphoid  (1)  is  a  sort  of  head  or  elongated  convexity,  and  those  of 
the  trapezium  (4)  and  the  trapezoid  (5)  are  two  facettes,  that  unite  in  forming  a  concavity, 
into  which  the  convexity  of  the  scaphoid  is  received.  This  small  articulation  is  strength- 
ened by  two  anterior  ligaments,  both  of  which  proceed  from  the  scaphoid,  and  are  connected 
one  to  the  trapezium,  and  the  other  to  the  trapezoid  ;  and  two  posterior,  arranged  in  a  sim- 
ilar manner  with  the  preceding,  but  much  thinner. 

A  single  synovial  capsule  (see  fig.  73),  very  loose,  especially  behind,  covers  the  corre- 
sponding articular  surfaces  of  the  two  rows.  But  it  is  also  provided  with  small  culs-de- 
sac,  which  penetrate  into  the  intervals  between  the  bones  of  each  row,  there  being  tliree 
below  and  two  above. 

Mechanism  of  the  Carpus. 

The  mechanism  of  the  carpus  must  be  considered  as  providing  both  for  strength  and 
mobility.  The  conditions  favourable  to  strength  are,  1.  The  number  of  bones  in  the  car- 
pus ;  2.  The  reciprocal  dovetailing  of  the  two  rows,  the  anti-brachial  row  joining  in  this 
fashion  the  metacarpal,  and  vice  versa ;  3.  The  numerous  ligaments  connecting  the  bones 
of  each  row  together.  The  carpus,  therefore,  has  power  to  resist  the  most  violent  shocks, 
chiefly  on  account  of  the  expenditure  offeree  at  each  of  its  numerous  articulations.  With 
regard  to  mobility,  the  movements  between  the  bones  of  each  row  must  be  distinguished 
from  those  which  take  place  between  the  two  rows.  1.  The  partial  movement  between 
the  component  bones  of  each  row  is  scarcely  appreciable,  and  requires  no  consideration. 
2.  The  mobility  of  the  two  rows  upon  each  other  is,  however,  more  marked.  The  enar- 
throdial articulation  of  the  head  of  the  Os  magnum  can  only  perform  forward  and  backward 
motions,  for  the  arthrodial  joints  on  each  side  prevent  any  lateral  movements. 

Mechanism  of  the  Carpal  Enarthrosis. — The  movement  of  extension  is  very  limited,  on  ac- 
count of  the  resistance  of  the  anterior  ligaments.  The  movement  of  flexion,  on  the  con- 
trary, is  much  more  considerable  :  it  may  be  carried  sufficiently  far  to  cause  luxation  of 
the  head  of  the  os  magnum  backward.  The  slight  structure  and  the  looseness  of  the  pos- 
terior hgaments,  and  also  the  looseness  of  the  synovial  membrane  behind,  explain  the  fa- 
cility which  this  articulation  enjoys  in  the  movements  of  flexion.  It  is  of  importance  to 
remark,  that  the  carpal  enarthrosis  performs  a  more  active  part  in  the  flexion  of  the  hand 
than  even  the  radio-carpal  articulation  ;  a  circumstance  of  the  highest  interest  in  relation 
to  the  mechanism  of  the  carpus. 

Metacaep.vl  Articulations. 
The  metacarpal  bones  are  united  at  their  extremities,  but  separated  along  their  shafts. 
We  shall  examine  the  articulations,  1.  Of  their  carpal ;  and,  2.  Of  their  digital  extremities. 

1.  Articulations  of  the  Carpal  Ends  of  the  Metacarpal  Bones. 

These  are  symphyses  or  amphi-arthroses.  The  articular  surfaces  {see fig.  73)  occupy  the 
sides  of  the  carpal  ends  of  the  metacarpal  bones,  and  are  partly  contiguous  and  partly  con- 
tinuous. The  contiguous  portion  consists  of  a  facette  covered  with  cartilage,  and  is,  in 
fact,  an  extension  of  the  surface  that  articulates  with  the  carpus.  The  part  intended  to 
become  continuous  is  rough. 

The  means  of  union  are  the  interosseous,  the  dorsal,  and  the  palmar  ligaments.  The  inter- 
osseous ligaments  (//,  fig.  73)  are  short,  close,  and  very  strong  bundles  of  fibres,  interposed 
between  the  rough  portions  of  the  lateral  facettes  of  two  neighbouring  metacarpal  bones. 
They  constitute  the  principal  means  of  uniting  these  bones,  as  may  be  seen  by  attemptinfl 


METACARPAL    ARTICULATIONS. 


149 


Fig  74. 


to  separate  them  after  dividing  the  dorsal  and  pahnai 
ligaments. 

The  dorsal  {I,  fig.  74)  and  palmar  ligaments  (m,  fig.  75) 
consist  of  fibrous  bundles,  stretched  transversely  from 
one  metacarpal  bone  to  another.  The  palmar  ligaments 
are  much  larger  than  the  dorsal. 

2.  Articulation  of  the  Digital  Ends  of  the  Metacarpal 

Bones. 
Although  the  digital  extremities  of  the  metacarpal 
bones  are  not,  prop- 
erly speaking,  artic- 
ulated together,  yet 
as  they  are  contigu- 
ous, and  move  upon 
each  other,their  sur- 
faces are  covered 
by  a  synovial  mem- 
brane, which  facil- 
itates their  move- 
ments ;  moreover,  a 
palmar  ligament  (n. 
Jigs.  74,  75)  is  stret- 
ched transversely 
in  front  of  these  ex- 
tremities, and  unites  them  loosely  together.  This  lig- 
ament (called  also  transverse)  is  common  to  the  last 
four  metacarpal  bones,  but  it  does  not  reach  the  met- 
acarpal bone  of  the  thumb.  It  may  be  considered  as 
formed  by  the  union  of  all  the  anterior  ligaments  ot 
the  metacarpo-phalangal  articulations,  and  as  being 
destined  to  render  these  ligaments  continuous.  In 
order  to  expose  this  ligament,  and  to  study  with  atten- 
tion its  connexions  with  the  anterior  ligaments  of  the 
metacarpo-phalangal  articulation,  it  is  sufficient  to 
open  the  fibrous  sheaths  of  the  flexor  tendons  of  the  fingers,  and  to  remove  the  smalllura- 
bricales  muscles,  together  with  the  nerves  and  vessels  of  the  fingers. 

We  may  consider  the  interosseous  palmar  aponeurOsity  as  representing,  in  respect  to 
the  shafts  of  the  metacarpal  bones,  the  aponeurosis  called  the  interosseous  ligament  in 
the  forearm.  Strictly  speaking,  the  thickened  inferior  border  of  the  dorsal  interosseous 
aponeurosis,  which  is  continuous  with  the  tendons  of  the  extensor  muscles,  might  be  con- 
sidered as  a  dorsal  transverse  ligament,  much  weaker  than  the  preceding. 

The  interosseous  muscles,  as  we  shall  afterward  see,  complete  the  means  of  union  of 
the  metacarpal  bones. 

Carpo-metacarpal  Articulations. 
The  articular  surfaces  are  the  inferior  facettes  on  the  bones  of  the  second  row  of  the 
carpus,  and  the  facettes  on  the  upper  ends  of  the  metacarpal  bones.  We  may  consider 
all  the  carpo-metacarpal  articulations  as  forming  only  one  joint  with  a  broken  surface. 
The  articulation  of  the  trapezium  with  the  metacarpal  bone  of  the  thumb,  and  that  of  the 
fifth  metacarpal  bone  with  the  os  unciforme,  require  each  a  special  description. 

Articulations  of  the  Second,  Third,  and  Fourth  Metacarpal  Bones  with  the  Carpus. 

Articular  Surfaces  {see  fig.  73). — ^The  articulation  of  the  second,  third,  and  fourth  met- 
acarpal bones  with  the  carpus  presents  a  sinuous  line,  which  might,  perhaps,  be  sub- 
jected to  certain  rules  of  disarticulation,  if  this  disarticulation  seemed  to  be  of  the  least 
use.  It  constitutes  a  tight  arthrodia,  with  an  angular  surface.  Proceeding  from  within 
outward,  the  fourth  and  third  metacarpal  bones  form  a  regular  curve,  with  the  concavity 
looking  upward ;  but  the  second,  which  unites  by  three  facettes  with  the  trapezium,  the 
trapezoid,  and  os  magnum,  presents  an  angular  surface.  The  second  metacarpal  bone 
is  jointed,  by  its  transversely  concave  surface,  Avith  a  facette  on  the  trapezoid,  which  is 
concave,  but  in  the  opposite  direction,  and  by  two  lateral  facettes,  with  the  os  magnum 
and  the  trapezium,  so  that  it  enters,  as  it  were,  into  the  carpus  by  two  angular  projec- 
tions, which  are  received  into  the  intervals  between  the  three  bones  with  which  it  is 
articulated.  From  this  it  follows,  that  the  carpo-metacarpal  articulations  present  not 
only  concave  and  convex  surfaces,  favourable  to  mobility,  but  also  angular  surfaces  thai 
evince  the  immobility  of  these  joints. 

Means  of  Union.  —  Some  ligaments,  distinguished  as  dorsal  and  palmar,  both  very 
strong,  short,  and  compact,  retain  the  articular  surfaces  as  immovably  in  contact  as  if 
the  joints  we-e  symphyses. 


150  ARTHEOLOGY. 

The  dorsal  ligaments  are  much  stronger  than  the  palmar,  and  are  composed  of  several 
layers,  the  deepest  being  the  shortest.  There  are  three  dorsal  ligaments  for  the  second 
metacarpal  bone  :  a  median  (o,  fig.  74),  stretched  to  it  from  the  trapezoid  bone  ;  an  exter- 
nal (p),  which  comes  from  the  trapezium,  and  covers  the  insertion  of  the  extensor  carpi 
radialis  longior ;  and  an  internal,  arising  from  the  os  magnum :  the  first  of  these  is  ver- 
tical, tlie  last  two  are  oblique.  There  are  two  dorsal  ligaments  in  the  articulation  of  the 
third  metacarpal  bone  :  a  vertical,  which  comes  from  the  os  magnum  ;  and  an  oblique  (r), 
from  the  OS  unciforme. 

In  the  articulation  of  the  fourth  metacarpal  bone  there  is  one  dorsal  ligament,  longer 
and  looser  than  the  preceding. 

The  palmar  ligainents  are  much  less  marked  than  the  preceding ;  contrasting  thus  with 
the  palmar  ligaments  of  the  carpus.  There  is  none  for  the  second  metacarpal  bone  ;  the 
tendon  of  the  flexor  carpi  radialis  appears  to  supply  the  place  of  this  ligament.  There 
are  three  ligaments  for  the  third  metacarpal  bone  :  an  external,  which  comes  from  the 
trapezium ;  a  middle,  proceeding  from  the  os  magnum ;  and  an  internal,  from  the  os  unci 
forme.  Lastly,  for  the  articulation  of  the  fourth  metacarpal  bone,  there  is  one  palmar 
ligament  from  the  os  unciforme. 

The  synovial  membrane  (see  fig.  ""rQ)  of  the  carpo-metacarpal  articulations  is  a  continu 
ation  of  the  synovial  membrane  of  the  carpus,  and  is  prolonged  between  the  upper  ends 
of  the  metacarpal  bones  ;  and,  as  the  synovial  membrane  of  the  carpus  communicates 
also  with  the  radio-carpal  joint,  it  can  be  conceived  what  ravages  may  be  produced  by 
inflammation  attacking  any  one  of  these  parts.  I  must  here  point  out  an  interosseous,  or 
lateral  ligament  (I,  fig.  73),  which  arises  from  the  os  magnum,  and  slightly,  also,  from 
the  OS  unciforme,  and  is  attached  to  the  inner  side  of  the  third  metacarpal  bone.  It  al- 
most completely  isolates  the  articulations  of  the  last  two  metacarpal  bones.  This  liga- 
ment being  attached  to  the  third  metacarpal  bone,  which  is  already  provided  with  very 
strong  ligaments,  increases  in  a  remarkable  manner  the  strength  of  the  joint. 

Carpo-metacarpal  Articulation  of  the  Thumb.- — This  joint  {m,fig.  73),  which  is  very  dis- 
tinct and  completely  separated  from  all  the  others,  is  remarkable,  also,  for  the  arrange- 
ment of  the  articular  surfaces.  There  is  a  mutual  jointing  between  the  trapezium,  which 
is  concave  transversely,  and  convex  from  behind  forward ;  and  the  first  metacarpal  bone, 
which  is  concave  and  convex  in  precisely  opposite  directions.  It  is  the  type  of  all  ar- 
ticulations by  mutual  reception. 

The  m£ans  of  union  consist  of  a  capsular  ligament  {s,  figs.  74  and  75),  imperfect  on  the 
outside,  where  its  place  is  occupied  occasionally  by  the  tendon  of  the  abductor  longus 
pollicis  (extensor  ossis  metacarpi  poUicis) :  it  is  much  thicker  behind  than  in  front,  and 
is  sufficiently  loose  to  permit  extensive  motions  in  all  directions.  There  is  a  separate 
synovial  membrane  for  this  joint,  which  is  remarkable  in  respect  of  its  relations  :  viz.,  1. 
Behind,  with  the  extensor  muscles  of  the  thumb ;  2.  On  the  outside,  with  the  expanded 
tendon  of  the  abductor  pollicis  ;  3.  On  the  inside,  with  the  interosseous  muscles  and  the 
radial  artery,  where  that  vessel  penetrates  into  the  palm  of  the  hand,  to  form  the  deep 
palmar  arch  ;  and,  4.  In  front,  with  the  muscles  of  the  baU  of  the  thumb. 

Carpo-metacarpal  Articulation  of  the  fifth  Metacarpal  Bone  {see  fig-  73). — The  articulation 
of  the  fifth  metacarpal  bone  with  the  os  unciforme  is,  in  many  respects,  analogous  to  the 
preceding ;  for  there  is  here,  also,  a  sort  of  mutual  reception  between  their  correspond- 
ing articular  surfaces.  There  is,  also,  a  kind  of  capsular  ligament  {t,  fig.  74),  very  strong 
in  front  and  thin  behind,  and  incomplete  on  the  outside,  on  account  of  the  presence  of 
the  fourth  metacarpal  bone  :  it  is  rather  loose,  and  maintains  the  relation  of  the  articular 
surfaces.  The  tendon  of  the  extensor  carpi  ulnaris  strengthens  this  joint  behind,  in  the 
same  manner  as  the  tendon  of  the  long  abductor  of  the  thumb  strengthens  the  articula- 
tion of  the  trapezium  and  the  first  metacarpal  bone. 

The  synovial  membrane  of  this  joint  belongs  also  to  the  fourth  metacarpal  bone.  The 
fourth  and  fifth  metacarpal  bones  may,  indeed,  be  strictly  considered  as  forming  only  one 
joint,  and  the  lateral  interosseous  ligament  as  completing  the  capsular  ligament.  On 
the  other  hand,  the  second  and  third  metacarpal  bones  form  a  very  distinct  articulation 
with  the  OS  magnum,  the  trapezoid,  and  a  small  facette  upon  the  trapezium ;  lastly,  there 
is  another  joint  peculiar  to  the  first  metacarpal  bone  and  the  trapezium.  There  are  thus 
three  distinct  joints  (see  fig.  73)  in  the  carpo-metacarpal  articulation,  in  one  of  which 
the  articular  surfaces  are  simple,  while  in  the  two  others  they  are  broken. 

Mechanism  of  the  Carpo-metacarpal  Articulations. 

The  mechanism  of  the  carpo-metacarpal  articulations  should  be  studied,  both  as  re- 
gards strength  and  mobility. 

I.  With  regard  to  strength,  the  metacarpal  bones  mutually  support  each  other,  and  resist 
in  common  the  action  of  external  agents  :  they  can  only  be  broken,  therefore,  by  violence 
suflicient  to  fracture  several  at  the  same  time.  In  order  that  any  one  should  be  broken 
alone,  the  violence  must  be  applied  directly  to  it.  In  this  manner  I  have  seen  the  third 
metacarpal  bone  fractured  by  the  stick  of  a  rocket. 

The  great  strength  of  the  metacarpus  depends  not  only  on  the  simultaneous  resistance 


ARTICULATIONS    OP   THE    FINGERS.  '1^1 

ot  its  component  parts,  but  also  on  the  intervening  articulations,  each  of  which  becomes 
the  seat  of  a  certain  expenditure  of  force  ;  for  part  of  this  being  employed  in  moving  the 
articular  surfaces  upon  each  other,  is  necessarUy  lost  as  far  as  its  direct  transmission  is 
concerned. 

With  regard  to  mobility,  these  articulations,  which  might  be  called  tight  angular  arthro- 
dias,  are  only  possessed  of  slight  gUding  motions,  on  account  of  the  angular  disposition 
of  the  articular  facettes,  the  sinuosity  of  the  common  articular  line,  and  the  strength  and 
shortness  of  both  the  external  and  the  interosseous  ligaments.  At  the  same  time  the 
mobility  of  all  the  metacarpal  bones  is  not  equal.  Thus,  the  articulation  of  the  trape- 
zium with  the  first  metacarpal  bone  holds  the  first  rank  ;  it  is  in  some  degree  different 
from  the  others  in  this  respect  as  well  as  in  position,  and  merits  particular  description. 
The  articulation  of  the  fifth  metacarpal  bone  holds  the  second  place,  and  that  of  the 
fourth  the  third.  The  articulations  of  the  second  and  third  metacarpal  bones  are  as  im- 
movable as  symphyses. 

Mechanism  of  the  Articulation  of  the  Trapezium  and  the  first  Metacarpal  Bone. — From  the 
mutual  reception  of  the  articular  surfaces,  this  articulation  permits  four  motions,  viz.,  flex- 
ion, extension,  abduction,  and  adduction,  and,  as  a  consequence  of  these,  circumduction. 

Flexion  is  not  performed  directly,  but  obliquely  inward  and  forward.  This  obhque  mo- 
tion produces  the  inovement  of  opposition,  which  characterizes  the  hand  ;  it  is  very  exten- 
sive, and,  when  carried  too  far,  may  produce  luxation  backward  with  the  greater  facility, 
because  the  capsular  hgament  is  very  thin  in  that  direction.  Extension  may  be  carried 
so  far  that  the  first  metacarpal  bone  may  form  a  right  angle  with  the  radius.  It  is  con- 
ceivable that  luxation  forward  might  be  produced  by  this  motion  ;  but  there  are  very  few 
causes  that  would  tend  to  increase  extension  to  such  a  degree,  and,  moreover,  the  ante- 
rior part  of  the  capsular  ligament  is  extremely  strong,  so  that  no  example  of  this  luxa- 
tion has  ever  been  recorded. 

Abduction  is  very  extensive  ;  when  carried  beyond  a  certain  point,  it  may  give  rise  to 
dislocation  inward,  for  the  trapezium,  being  situated  on  a  plane  anterior  to  the  root  of  the 
metacarpus,  the  neighbouring  metacarpal  bones  offer  no  obstacle  to  such  a  displacement. 

Lastly,  direct  adduction  is  limited  by  the  meeting  with  the  second  metacarpal  bone. 

Mechanism  of  the  Articulation  of  the  fifth  Metacarpal  Bone  with  the  Cuneiform. — This  ar- 
ticulation in  some  degree  resembles  the  preceding,  and,  like  the  last,  it  would  be  liable 
to  dislocation,  were  it  not  for  its  intimate  connexions  with  the  other  metacarpal  bones, 
so  that  the  same  cause  that  would  tend  to  displace  the  fifth  metacarpal  bone  would  also 
tend  to  displace  the  fourth. 

Articulations  of  the  Fingers  (.figs.  74  and  75). 

These  comprise,  1.  The  articulations  of  the  fingers  with  the  metacarpal  bones.  2.  The 
articulations  of  the  phalanges  together. 

Metacarpo-phalangal  Articulations. 

These  belong  to  the  class  of  condyloid  articulations. 

The  articular  surfaces  in  each  are  formed  by  the  head  of  the  metacarpal  bone,  flattened 
from  side  to  side,  increasing  in  breadth  from  the  dorsal  to  the  palmar  aspect,  and  pro- 
longed much  farther  in  the  latter  direction,  where  it  presents  the  trace  of  a  division  into 
two  condyles ;  and  by  the  shallow  glenoid  cavity  of  the  first  phalanx,  which  is  trans- 
versely oblong,  and,  consequently,  has  its  long  diameter  at  right  angles  to  tliat  of  the  head 
of  the  metacarpal  bone,  which  is  oblong  from  before  backward.  We  see,  then,  that  an 
articular  head,  elongated  from  before  backward,  is  adapted  to  a  transversely  oblong  cav- 
ity. This  arrangement  favours  the  movements  of  flexion  and  extension,  as  well  as  the 
lateral  motions,  which  are  as  extensive  as  they  would  have  been  had  all  the  diameters 
of  the  articular  surfaces  been  equal  to  those  which  are  actually  the  longest. 

It  is  on  account  of  the  lateral  flattening  of  the  heads  of  the  metacarpal  bones  that,  in 
amputations  at  these  joints,  surgeons  make  choice  of  lateral,  in  preference  to  antero- 
posterior flaps. 

Means  of  Union. — On  account  of  the  disproportion  just  noticed  as  existing  between 
the  articular  surfaces  of  this  joint,  the  glenoid  cavity  of  the  first  phalanx  not  being  equal 
to  more  than  one  half  of  the  articular  surface  on  the  metacarpal  bone,  this  cavity  is  pro- 
vided with  a  ligament  called  the  anterior  ligament  {u,f.g.  75),  which  was  confounded  by 
the  older  anatomists  with  the  fibrous  sheaths  of  the  flexor  tendons.  This  ligament  I 
have  called  the  glenoid  ligament,  and  its  use  is  to  complete  the  cavity  of  reception  ol 
the  metacarpal  condyle.  It  is  situated  on  the  palmer  aspect  of  the  joint,  and  is  grooved 
anteriorly,  to  correspond  with  the  flexor  tendons.  It  is  concave,  forming,  so  to  say,  a 
demi-capsule  behind,  to  correspond  with  the  metacarpal  condyle.  By  its  edges  it  is  con- 
tinuous not  only  with  the  transverse  metacarpal  ligament,  which  is  one  ol'  its  appurte- 
nances, but  also  with  the  sheath  of  the  flexor  tendons,  and  with  the  lateral  ligaments  of 
the  joint.  By  its  superior  border  this  ligament  is  continuous  with  the  palmar  interos- 
seous aponeurosis,  and  with  the  digital  bands  of  the  palmar  aponeurosis.  By  its  lower 
edge  it  is  finnly  fixed  to  the  anterior  part  of  the  margin  of  the  first  phalangal  articular 


152  ARTHROLOGY. 

surface ;  its  upper  edge  is  loosely  connected  by  some  ligamentous  fibres  to  the  contract 
ed  neck  which  supports  the  head  of  the  metacarpus,  and  is  accurately  adapted  to  that 
neck.  The  anterior  or  capsular  ligament  is  very  thick,  unyielding,  formed  of  fibres  that 
cross  each  other,  and  look  like  mother-of-pearl,  and  is  as  compact  as  cartilage.  Several 
times  I  have  found  a  sesamoid  bone  in  the  substance  of  the  anterior  ligament  of  the  in- 
dex and  the  middle  finger.  The  whole  tendinous  sheath  of  the  tendons  of  the  flexor 
muscles  may  be  considered  as  making  part  of  this  anterior  ligament,  and  we  ought  not 
to  overlook  these  tendons  in  estimating  the  solidity  of  the  joint  with  regard  to  flexion. 
This  joint  has  two  lateral  ligaments,  which  are  extremely  unyielding,  an  internal  and  an 
external ;  they  are  inserted  into  a  marked  tubercle  existing  posteriorly  on  each  side  of 
the  lower  extremities  of  the  metacarpal  bones,  and  into  a  very  remarkable  depression 
below  and  before  this  tubercle ;  hence  these  ligaments  extend  very  obliquely  from  be- 
hind forward  and  from  above  downward,  in  the  shape  of  a  strong  and  flat  band,  looking 
like  mother-of-pearl,  which  continually  expands  and  irradiates,  and  finally  terminates,  1 . 
In  a  tubercle  existing  anteriorly,  and  on  each  side  of  the  margin  of  the  upper  end  of  the 
first  phalangal  bone.     2.  By  its  superior  fibres  into  the  borders  of  the  anterior  ligament. 

These  lateral  ligaments  extend,  therefore,  obUquely  from  the  posterior  tubercle  of  the 
lower  end  of  the  metacarpus  to  the  anterior  tubercle  of  the  upper  end  of  the  first  phalan- 
gal bone ;  they  are  stretched  by  flexion,  which  cannot  be  extended  beyond  the  right 
angle  without  the  ligaments  being  torn  ;  and  they  are  relaxed  by  extension,  except  that 
portion  of  these  ligaments  which  goes  to  the  anterior  ligament,  and  which  limits  the  ex- 
tension by  its  resistance.  It  may  be  interesting  to  remark,  that  the  external  lateral  lig- 
ament is  much  stronger  than  the  internal ;  the  former  of  these  ligaments  is  inserted  not 
only  into  the  tubercle,  but  also  into  the  whole  extent  of  the  subjacent  depression. 

There  is  no  dorsal  ligament  properly  so  called  ;  its  place  is  evidently  supplied  by  the 
corresponding  extensor  tendon  (lo,  fig.  74).  This  extensor  tendon,  after  having  reach- 
ed the  level  of  the  joint,  becomes  nan-ow,  and  contracts,  as  it  were,  upon  itself,  in  order 
to  form  a  thick  and  extremely  compact  cord.  From  each  edge  of  this  ligament  an  apo- 
neurotic expansion  arises,  which  is  inserted  into  the  sides  of  the  joint. 

The  synodal  capsule  is  extremely  loose,  especially  on  the  aspect  of  extension  ;  it  does 
not  adhere  to  the  tendon,  but  is  folded  upon  itself  during  extension,  and  is  stretched  du- 
ring flexion :  it  lines  the  inner  surface  of  the  lateral  ligaments,  and  is  reflected  upon  the 
articular  cartilages. 

Metacarpal-phalangal  Articulation  of  the  Thumb. — Two  sesamoid  bones  (x,  figs.  73  and 
75)  are  annexed  to  this  articulation  in  front,  and  are  constantly  found  in  the  glenoid  lig- 
ament ;  they  aflJbrd  insertion  to  the  lateral  ligaments  and  to  aU  the  short  muscles  of  the 
thmnb. 

If  we  examine  these  articulations  in  connexion,  we  shall  find  that  they  are  disposed 
in  a  curved  line,  with  the  convexity  looking  downward.  This  curvature  is  slightly  in- 
terrupted at  the  articulation  of  the  fourth  metacarpal  bone,  which  is  not  on  a  level  with 
those  of  the  index  and  the  middle  fingers. 

Mechanism  of  the  Metacarpo-phalangal  Articulations. 

We  shall  take  as  an  example  the  metacarpo-phalangal  articulation  of  the  middle  fin- 
ger. From  the  arrangement  of  the  articular  surfaces,  it  is  evident  that  this  articulation 
can  execute  movements  in  four  principal  directions,  and,  consequently,  those  of  circum- 
duction also.  From  a  simple  inspection  of  the  surfaces,  it  might  be  inferred  that  the 
movement  of  flexion  must  be  very  extensive,  while  that  of  extension  (or  flexion  back- 
ward) and  the  lateral  motions  of  abduction  and  adduction  are  exceedingly  limited.  The 
arrangement  of  the  ligaments  amply  confirms  these  suppositions.  It  should  be  noticed, 
as  a  rare  exception,  that  in  the  movements  executed  by  this  joint,  it  is  not  the  head  that 
moves  upon  the  cavity,  but  the  cavity  that  moves  upon  the  head. 

In  flexion,  the  first  phalanx  glides  forward  upon  the  head  of  the  corresponding  metacar- 
pal bone  ;  the  extensor  tendon  and  the  back  of  the  synovial  capsule  are  stretched  by  the 
projecting  head  of  this  bone  :  the  posterior  fibres  of  the  lateral  ligaments  are  also  stretch- 
ed ;  they  limit  the  movement  of  flexion,  allowing  it  only  to  proceed  so  far  that  the  pha- 
lanx forms  a  right  angle  with  the  metacarpal  bone.  Lastly,  flexion  can  be  carried  some- 
what farther  by  the  thumb,  the  ring,  and  the  little  fingers,  than  by  the  others.  In  ex- 
tension, the  phalanx  glides  backward  upon  the  head  of  the  metacarpal  bone  supporting  it : 
this  head  corresponds  almost  entirely  with  the  anterior  ligament,  which,  as  we  have  seen, 
is  disposed  in  the  shape  of  a  fibrous  demi-capsule.  The  posterior  fibres  of  the  lateral 
ligaments  are  relaxed,  and  the  anterior  stretched.  The  motion  is  evidently  limited  by 
the  anterior  or  capsular  ligament,  and  by  the  anterior  fibres  of  the  lateral  ligaments, 
which  are  inserted  into  this  anterior  ligament.  I  may  remark,  that  the  upper  border  of 
this  anterior  ligament  forms  a  sort  of  ring  or  collar,  which  surrounds  ahnost  entirely  the 
neck  of  the  corresponding  metacarpal  bone,  without  adhering  to  it. 

According  to  the  relative  size  of  this  ring,  and  the  comparative  looseness  of  the  glenoid 
ligament,  will  the  movement  of  extension  be  more  or  loss  considerable.  In  all  persons 
\t  may  be  carried  so  far  as  to  form  *n  obtuse  angle  behind  ;  in  some,  until  a  right  anglo 


ARTICULATIONS   OF    THE   FINGERS.  153 

is  formed  ;  and  in  a  few,  even  so  far  as  to  produce  an  incomplete  luxation,  reducible  by 
the  sliglitest  muscular  effort.  If  extension  be  carried  beyond  these  limits  (for  which, 
however,  considerable  violence  is  necessary),  the  head  of  the  metacarpal  bone  will  escape 
from  the  kind  of  collar  formed  by  the  superior  border  of  the  capsular  ligament  and  the 
anterior  fibres  of  the  lateral  ligaments,  sometimes  by  extensively  lacerating  it,  but  at 
others  only  by  stretching  it  very  much ;  in  both  cases  the  first  phalanx  is  dislocated  back- 
ward, or  the  metacarpal  bone  forward.  When  the  collar  is  not  torn,  reduction  is  al- 
most impossible,  because  the  glenoid  hgament  is  always  interposed  between  the  articular 
surfaces.  It  should  be  remarked,  that  the  metacarpo-phalangal  articulation  of  the  thumb 
is  the  only  one  which  is  not  capable  of  flexion  backward.  This  is  probably  owing  to 
the  want  of  looseness  in  its  aaterior  or  capsular  ligament.  In  this  joint,  the  movement 
of  extension  does  not  go  beyond  the  straight  line  ;  in  this  respect  it  resembles  the  ar- 
ticulations which  the  phalanges  form  with  each  other.* 

Adduction  and  abduction  consist  of  simple  latered  glidings,  limited  by  the  meeting  of 
the  other  fingers. 

Articulations  of  the  Phalanges  of  the  Fingers. 

These  are  pulley-like  joints,  or  perfect  angular  ginglymi.  There  are  two  articulations 
of  this  kind  in  each  finger,  but  only  one  in  the  thumb. 

Articular  Surfaces. — The  lower  end  of  the  first  phalanx,  flattened  from  before  back- 
ward, presents  a  trochlea,  broader  on  the  pahnar  than  on  the  dorsal  aspect,  and  prolonged 
much  farther  in  front  than  behind.  The  trochlea  of  the  phalanx  resembles  the  lower 
end  of  the  femur,  with  tjiis  difference,  that  its  two  condyles  are  not  separated  from  each 
other.  The  upper  end  of  the  second  phalanx,  also  flattened  from  before  backward,  pre- 
sents two  small  glenoid  cavities,  separated  by  an  antero-posterior  ridge.  The  ridge  cor- 
responds to  the  groove  of  the  pulley,  and  the  glenoid  cavities  to  the  two  condyles. 

Means  of  Union. — 1.  An  anterior  ligament  {,y,fig.  74),  grooved  anteriorly,  to  serve  the 
tendon  as  a  sheath,  and  exactly  resembling  what  exists  in  the  metacarpo-phalangal  ar- 
ticulations, and  performing  the  same  office  of  deepening  the  glenoid  cavity,  which  by  it- 
self only  imperfectly  receives  the  pulley  of  the  first  phalanx.  2.  Two  lateral  ligaments, 
an  internal  {z)  and  an  external  {z'),  arranged  precisely  in  the  same  manner  as  the  lateral 
ligEiments  of  the  metacarpo-phalangal  articulations.  They  are  attached  to  tubercles 
situated  behind  the  lateral  depressions,  on  the  lower  end  of  the  first  phalanx,  and  pass 
obliquely  forward,  to  be  inserted  both  into  the  glenoid  ligament  and  the  second  phalanx. 
There  is  no  posterior  ligament,  its  place  being  supplied  by  the  extensor  tendon.  This 
tendon  is  disposed  in  a  peculiar  manner  :  it  gives  off  constantly  a  prolongation  (w)  from 
its  anterior  aspect,  which  is  inserted  into  the  upper  end  of  the  second  phalanx,  so  that 
this  bone  presents  a  somewhat  similar  arrangement  behind,  as  it  does  in  front,  with  the 
flexor  tendon.     This  prolongation  has  a  cartilaginous  aspect. 

The  synovial  capsule  is  precisely  similar  to  that  of  the  metacarpo-phalangal  joints. 
The  foregoing  description  applies  equally  well  to  the  articulation  of  the  second  with  the 
third  phalanx.  There  is  often  a  sesamoid  bone  in  the  substance  of  the  glenoid  ligament 
of  the  two  phalangal  joints  of  the  thumb. 

Mechanism  of  the  Phalanges. 
The  fingers  are  essentially  the  organs  of  prehension  and  of  touch.  In  the  mechanism 
of  touch,  the  fingers  are  moved  over  the  surfaces  of  bodies,  and  are  moulded  upon  even 
their  slightest  inequalities,  sometimes  acting  together,  sometimes  separately,  seizing  and 
moving  between  them,  as  between  the  blades  of  sentient  forceps,  even  the  most  delicate 
objects.  For  the  performance  of  this  function,  great  mobility  must  be  conjoined  with 
great  precision  of  movement.  On  the  other  hand,  for  the  purpose  of  seizing  bodies,  of 
retaining,  repulsing,  or  breaking  them,  as  well  as  of  acting  as  the  means  of  attack  and 
defence,  considerable  power  is  required  ;  all  which  qualities  are  united  in  the  mechanism 
of  the  hand.  Observe  the  number  of  the  fingers  and  their  complete  isolation,  so  that 
they  can  act  either  together  or  separately,  and  even  in  opposite  directions.  Notice  the 
number  of  the  phalanges,  their  successive  decrease  in  size,  and  the  facility  with  which 
they  can  be  separated  or  made  to  approach  each  other,  so  as  to  be  apphed  around  spher- 
ical bodies.  Note,  also,  the  inequality  of  the  fingers  in  length  and  power,  enabling  each 
to  act  a  determinate  part  in  prehension ;  and,  above  all,  remark  the  shortness  of  the  thumb, 
which  only  reaches  the  base  of  the  first  phalanx  of  the  index  finger  ;  but  which,  placed 
as  it  is  upon  a  plane  anterior  to  the  rest,  and  endowed  with  a  greater  degree  of  mobili- 
ty, can  be  opposed  to  all  the  fingers  together,  to  each  finger  separately,  and  to  every  pha- 
lanx of  each,  thus  constituting  the  principal  blade  of  the  sentient  forceps  represented  by 
the  hand  ;  for,  being  more  strongly  constructed,  and  provided  with  more  powerful  mus- 
cles than  the  other  fingers,  it  in  some  degree  counterbalances  them  all. 

*  This  is,  I  believe,  the  anatomical  reason  why  a  reduction  of  the  dislocations  forward  of  the  n^tacarpo- 
phalan^l  articulations  of  the  thumb  and  the  other  fingers  is  difficult,  and  sometimes  impossible  The  most 
skilful  practitioners  have  sometimes  failed  in  this  reduction,  and  especially  in  dislocations  of  the  thumb;  ^n- 
grene  and  death  have  often  taken  place  in  consequence  of  the  violent  attempts  at  reduction.  I  am  certain  that 
the  vertical  section  of  the  anterior  ligament  wotfld  obviate  the  difficultj'  at  once. 

u 


-'IM  ARTHROLOGY. 

.;'  ...  ^.rxbT^aXw^  Meckanism  of  the  Phtdangal  Articulations. 
f^i  From  the  shape  of  the  articular  surfaces,  which  form  a  miniatiire  representation  o£ 
*the  knee,  it  is  evident  that  the  only  motions  of  which  these  joints  are  capable  are  flex- 
ion and  extension.  The  flexion  of  the  second  upon  the  first  phalanx  is  as  extensive  as 
it  could  possibly  be,  for  it  is  only  limited  by  the  meeting  of  the  anterior  surfaces  of  these 
bones.  The  amount  oi flexion  of  the  third  phalanx  upon  the  second  is  less  considerable. 
The  extension  of  the  second  phalanx  upon  the  first,  and  that  of  the  third  upon  the  second, 
are  limited,  as  in  the  metacarpo-phalangal  joints,  by  the  anterior  glenoid  and  the  lateral 
ligaments.  This  motion  of  the  phalanges  is  extremely  slight ;  I  have  never  seen  them 
carried  farther  back  than  to  form  a  straight  line. 

From  what  has  been  observed,  it  follows  that,  as  regards  its  movements,  each  finger 
'represents  a  shortened  or  miniature  limb  ;  that,  at  its  articulation  with  the  metacarpus, 
it  is  capable  of  motions  in  every  direction,  and  also  of  circumduction  ;  that,  from  the 
joints  between  the  phalanges,  it  is  endowed  with  the  power  of  strong,  extensive,  and 
accurate  flexion  ;  and  that,  from  the  double  bending  of  the  second  upon  the  first,  and  the 
third  upon  the  second  phalanges,  the  fingers  represent  a  true  hook  for  seizing  and  cling 
ing  to  external  objects. 


ARTICULATIONS  OF  THE  INFERIOR  OR  ABDOMINAL  EXTREMITIES. 

Articulations  of  the  Pelvis. — Coxo-femoral. — Knee-joint. — Peroneo-tibial. — Ankle-joint.— 
Of  the  Tarsus. — Tarso-metatarsal. — Of  the  Toes. 

Articulations  of  the  Pelvis  {figs.  76,  77). 
The  articulations  of  the  pelvis  are,  1.  The  sacro-iliac  symphysis  ;  2.  The  symphysis 
pubis ;  and,  3.  The  sacro-coccygeal  articulation.    The  last  has  been  already  described  with 
the  other  articulations  of  the  vertebral  column. 

Sacro-iliac  Symphysis. 
Preparation. — 1.  Detach  the  pelvis  from  the  rest  of  the  trunk  ;  2.  Saw  through  the  hor- 
izontal ramus  and  arch  of  the  pubes  at  the  distance  of  about  eighteen  lines  on  each  side 
of  the  symphysis  ;  3.  Dislocate  the  os  innominatum  of  one  side  ;  4.  Dissect  the  anterior 
ligaments  of  the  sacro-iliac  symphysis  upon  the  other  ;  5.  Then  make  a  horizontal  section 
of  that  articulation,  dividing  it  into  an  upper  and  a  lower  half 
The  sacro-iliac  articulation  belongs  to  the  class  of  symphyses  or  amphi-arthroses. 
The  articular  surfaces  are  formed  on  the  sacrum  and  os  innominatum,  and  are  partly 
contiguous  and  partly  continuous.     The  contiguous  surfaces  of  these  two  boneS  are  an- 
terior to  the  others,  and  are  shaped  like  an  ear,  with  the  convex  edge  turned  forward  ; 
hence  they  are  called  the  auricular  surfaces.     The  parts  which  are  rendered  continuous 
by  means  of  ligamentous  fibres  consist  of  the  entire  space  comprised  between  the  auric- 
ular portion  and  the  posterior  border  of  the  os  innominatum,  and  of  all  the  lateral  sur- 
face of  the  sacrum  not  occupied  by  the  auricular  facette.     The  continuous  portions  are 
both  marked  with  very  rugged  eminences  and  depressions.    These  articular  surfaces  are 
also  remarkable  from  being  sinuous  and  alternately  concave  and  convex,  and  from  their 
presenting  a  well-marked  obliquity  in  two  directions,  viz.,  from  above  downward,  and  from 
before  backward  and  inward,  so  that  the  sacrum  is,  as  it  were,  wedged  between  the  ossa 
innominata  both  in  a  vertical  and  an  antero-posterior  direction. 
Means  of  Union. — The  auricular  surfaces  are  covered  with  cartilage,  which  is  thicker 
Fig.  76.  upon  the  sacrum  than  on  the  os  innominatum, 

and  is  remarkable  for  the  roughness  of  its 
surface,  which  contrasts  with  the  smooth  ap- 
pearance of  other  articular  cartilages.  There 
is  a  distinct  synovial  membrane  in  this  joint 
in  the  infant  and  pregnant  female,  but  it  can 
scarcely  be  detected  in  the  adult  and  the 
aged.  The  ligaments  are,  1.  An  anterior  sa- 
cro-iliac ligament  (b,  figs.  76,  77),  a  very  thin 
layer  which  passes  in  front  of  this  articula- 
tion, and  composed  of  fibres  stretched  trans- 
versely from  the  sacrum  to  the  ilium.  2.  A 
superior  sacro-iliac  ligament  ii,fig-  52),  a  very 
thick  bundle,  extending  transversely  from 
the  base  of  the  sacrum  to  the  contiguous 
portion  of  the  ilium.  3.  An  interosseous  lig- 
_^  ament,  which    forms  the  strongest  bond  of 

onion  in  this  joint,  composed  of  a  great  number  of  ligamentous  fibres,  stretched  horizon- 
tally from  the  ilium  to  the  sacrum,  crossing  each  other,  and  filling  up  almost  the  whole  of 
the  deep  excavation  comprised  between  the  two  bones ;  these  fibres  leave  small  inter- 


ARTlCUL'A*'nroN^'^bF  *rHE   PELVIS.  155 

vals  between  them,  which  are  occupied  by  fat,  and  traversed  by  numerous  small  veins. 
One  of  these  bundles  merits  a  special  description  :  it  consists  of  a  long  and  strong  band 
extending  almost  vertically  from  the  posterior  superior  spinous  process  of  the  ilium  to  a 
thick  tubercle  on  the  third  sacral  vertebra  ;  it  may  be  caUed  the  posterior  vertical  sacra-iliac 
ligament.  4.  The  ilia-lumbar  ligament  {c,figs.  76,  77)  maybe  considered  as  belonging  to 
this  joint ;  it  extends  from  the  summit  of  the  transverse  process  of  the  fifth  lumbar  ver- 
tebra to  the  thickest  part  of  the  crest  of  the  ilium,  that  is,  to  the  enlargement  situated 
about  two  inches  in  front  of  the  posterior  superior  iliac  spine.  It  is  a  thick  and  very 
strong  triangular  bundle. 

Symphysis  Pubis. 

Preparatian. — This  requires  no  special  direction  :  only,  in  order  to  become  acquainted 
with  the  respective  extent  of  the  contiguous  and  continuous  portions,  it  is  necessary  to 
make  two  sections,  a  horizontal  section,  and  also  a  vertical  one  from  before  backward. 

The  articular  surfaces  {e,fig.  77)  are  oval,  having  their  longest  diameters  directed  ver- 
tically ;  they  are  flat,  and  obliquely  cut  from  behind  forward  and  outward.  Tliey  are, 
therefore,  separated  by  a  triangular  interval,  the  base  of  which  is  directed  forward,  and 
the  apex  backward.  We  should  observe,  concerning  this  articulation,  that  there  are  many 
varieties  in  the  respective  extent  of  the  contiguous  and  continuous  portions  of  the  artic- 
ular surfaces.  Sometimes  they  are  almost  wholly  continuous  ;  at  other  times,  on  the 
contrary,  they  are  nearly  altogether  contiguous.  I  have  observed  this  latter  disposition 
in  a  very  remarkable  degree  in  the  symphysis  of  a  young  woman  who  died  in  the  sixth 
month  of  pregnancy. 

The  means  ofuruon  are  the  following  :  1.  Aii  anterior  pubic  ligament  {d,fig.  76),  a  very 
thin  fibrous  layer,  the  posterior  portion  of  which  is  blended  with  the  interosseous  liga- 
,  ment :  it  is  composed  of  fibres  extending  from  the  spine  of  each  os  pubis  obliquely  to  the 
anterior  surface  of  the  opposite  pubic  bone  ;  those  from  the  left  side  pass  in  front  of  those 
from  the  right.  2.  A  posterior  pubic  ligament,  extremely  thin,  and  covering  the  prominence 
formed  by  the  ossa  pubis  behind,  at  the  place  of  their  articulation.  This  prominence, 
which  is  very  marked  in  old  subjects,  seems  to  be  produced  by  a  jutting  out  of  the  poste- 
rior table  of  the  bone  backward,  apparently  caused  by  the  pressure  of  one  articular  sur- 
face upon  the  other  ;  these  surfaces  being,  as  we  have  described,  in  contact  behind,  but 
separate  in  front.  In  a  female  who  died  of  peritonitis  soon  after  delivery,  I  found  this 
posterior  prominence  of  the  pubes  fonning  a  sort  of  spine  of  some  lines  in  diameter  from 
before  backward.  3.  A  superior  pubic  ligament  {e,fig.  76),  very  thick,  and  continuous  on 
each  side,  with  a  fibrous  cord,  that  covers  the  upper  edge  of  the  os  pubis,  and  effaces  its 
irregularities.  4.  An  inferior  pubic  or  triangular  ligament  (/,  fig.  76),  which  is  exceed- 
ingly strong  ;  it  forms  a  continuation  of  the  anterior  and  interosseous  ligaments,  and  is 
composed  of  interlacing  fibres  :  this  ligament  renders  the  angle  formed  by  the  ossa  pubis 
obtuse,  and  gives  to  the  arch  of  the  pubes  that  regular  curve  presented  by  it  to  the  head 
of  the  foetus  during  labour.  5.  An  interosseous  ligament  (e,  fig.  77),  which  occupies  the 
whole  non-contiguous  portion  of  the  articular  surfaces,  and  varies  greatly  in  thickness  in 
different  individuals.  This  hgament  forms  the  principal  means  of  union  between  the 
bones  of  the  pubes  ;  it  fills  up  the  vacant  space  of  a  line  and  a  half  to  two  lines,  which 
exists  between  the  articular  surfaces,  and  is  composed  of  fibres,  which  cross  each  other 
like  those  of  the  intervertebral  substances.* 

Of  the  Sub-pubic  or  Obturator  Membrane,  and  the  Sacro-sciatic  Ligament. 
We  place  the  description  of  the  obturator  and  sacro-sciatic  ligaments  next  to  that  of 
the  articulations  of  the  pelvis,  simply  remarking  that  they  can  scarcely  be  considered 
true  ligaments,  but  rather  aponeuroses,  which  serve  to  complete  the  parietes  of  the  pel- 
vis, without  contributing  anything  to  the  strength  of  the  pelvic  articijations.  In  trying 
to  account  for  the  great  obturator  foramen  and  the  great  sciatic  notch,  I  have  asked  my- 
self the  question  whether  these  great  openings,  independently  of  their  transmitting  ves- 
sels, nerves,  and  muscles,  did  not  result  from  that  law  of  osteology,  by  means  of  which 
the  bones,  the  levers  of  the  muscular  power,  are  formed  with  the  least  possible  weight 
and  volume.  How  much  heavier  would  the  pelvis  have  been,  if  the  obturator  foramen 
and  the  great  sciatic  notch  had  been  filled  with  osseous  tissue.  It  would  have  been  use- 
less, for  the  strength  of  the  pelvis  would  not  have  been  increased  in  any  way  by  such  an 
arrangement.  Perhaps  these  strong  but  flexible  membranes  are  also  useful  during  the 
progress  of  labour,  by  diminishing  the  pressure  of  the  soft  parts  of  the  mother  between 
the  head  of  the  child  and  the  bones  of  the  pelvis. 

*  From  analogy,  we  may  infer  aa  identical  disjjosition  in  the  pubic  and  vertebral  symphysis.  Thus  it  will  be 
seen  that  the  articular  surfaces  in  these  two  articulations  are  not  fitted  to  each  other.  In  the  syniphyis  pubis, 
however,  we  discover  an  additional  degree  of  mobility  ;  the  articular  surfaces  are  contiguous  to  a  greater  ex- 
tent, and  the  synovial  membrane  is  so  perfect  that  no  anatomist  has  yet  doubted  it.  The  symphysis  pubis 
might,  therefore,  be  regarded  as  the  transition  between  the  movable  aiticulations  and  the  rai.ved  or  symphy- 
ses. The  obliquity  in  an  inverse  direction  of  the  articular  surfiices  is  the  cause  why  the  syraphysis  pubis  is 
much  larger  in  front  than  behind  ;  hence,  in  symphyseotomy  or  a  section  of  the  symphysis,  the  knife  must  be  ap- 
plied to  the  anterior  portion  of  the  symphysis,  so  tjiat  the  articulation  may  be  entered  into  with  more  safety. 
It  is  clear  that  a  trocar  could  not  be  thrust  into  the  bladder  through  the  symphysis,  on  accojnt  of  Us  bemj  too 
narrow  behind  to  admit  of  its  passage. 


166  ARTHROLOGY. 

Sub-pubic  or  Obturator  Membrane  {g,  figs.  76,  77). — This  membrane  closes  the  obtura- 
tor (sub-pubic)  foramen,  excepting  at  its  upper  part,  where  we  find  a  notch,  by  which  the 
groove  for  the  obturator  vessels  and  nerves  is  converted  into  a  canal.  The  external 
half  of  its  circumference  is  attached  to  the  corresponding  margin  of  the  obturator  fora- 
men, and  the  internal  half  to  the  posterior  surface  of  the  ascending  ramus  of  the  ischi- 
um ;  its  two  surfaces  give  attachment  to  the  obturator  muscles.  The  obturator  mem- 
brane is  composed  of  aponeurotic  bundles,  which  look  like  mother-of-pearl,  and  are  in- 
terlaced in  every  direction.  An  interesting  point  of  its  structure  is  its  being  formed  of 
several  layers  of  fibres,  and  small  bristle-shaped  collections  of  fibres  arising  constantly 
from  the  internal  half  of  the  margin  of  the  obturator  foramen,  which  expand  upon  the 
anterior  surface  of  the  membrane,  and  afterward  intermingle  with  the  periosteum. 
There  is  also  to  be  found  a  very  strong  parcel  arising  from  a  sort  of  spine  upon  the  mar- 
gin of  the  obturator  foramen,  immediately  above  the  level  of  the  great  cotylo  d  notch. 

Sacro-sciatic  Ligaments. — These  are  divided  into  the  great  and  the  S7nah .  ^'e  apply 
the  term  ligaments  to  them  rather  on  account  of  their  fasciculated  shape  than  fron»  their 
use,  which  scarcely  has  reference  to  the  union  of  the  bones  of  the  pelvis. 

The  great  sacro-sciatic  ligament  {I,  figs.  76,  77)  arises  from  a  ridge  situated  on  the  in- 
ternal hp  of  the  tuberosity  of  the  ischium,  and  also  from  the  ascending  ramus  of  the 
same  bone,  by  a  curved  margin  of  considerable  extent,  having  its  concavity  directed  up- 
ward, which,  with  the  inner  surface  of  the  tuberosity  of  the  bone,  forms  a  groove  for  the 
protection  of  the  internal  pubic  vessels  and  nerves.  The  most  superficial  fibres  of  this 
ligament  are  partly  continuous  with  the  common  tendon  of  the  biceps  and  the  semi-ten- 
dinosus.  Immediately  after  its  origin,  from  its  fibres  being  collected  together,  it  be- 
comes very  narrow  and  thick,  and  is  directed  upward  and  inward  ;  it  then  expands  con- 
siderably, and  is  inserted  into  the  edges  of  the  sacrum  and  coccyx,  and  more  slightly 
into  the  posterior  part  of  the  crest  of  the  ilium,  as  far  as  the  posterior  and  superior  spi- 
nous process  of  this  bone.  Its  upper  edge,  or,  rather,  its  external,  is  vertical,  and  is 
continuous  with  the  aponeurosis,  extending  over  the  pyriformis  muscle.  Its  internal 
edge,  which  forms  a  curve,  and  which  is  almost  horizontal,  makes  part  of  the  inferior 
circumference  of  the  small  pelvis  ;  it  fines  the  small  sacro-sciatic  ligament,  to  which  it 
adheres  at  its  insertion  into  the  coccyx,  and  from  which  it  is  separated  externally  by  a 
triangular  space,  where  it  is  in  relation  with  the  internal  obturator  muscle  ;  it  is  covered 
by  the  gluteus  maximus,  to  which  it  furnishes  a  great  number  of  aponeurotic  insertions. 
This  disposition  increases  the  thickness  of  this  ligament  considerably,  and  gives  to  its 
posterior  surface  the  rugged,  rough,  and,  as  it  were,  lacerated  aspect,  which  is  a  char- 
acteristic of  that  surface.  The  great  sacro-sciatic  ligament  is  composed  of  bundles,  sev- 
eral of  which,  on  a  level  with  the  narrowest  portion  of  this  ligament,  are  interlaced  in 
the  shape  of  the  letter  X.  Several  of  these  ligaments,  which  are  external  at  their  sci- 
atic insertion,  become  internal  at  their  insertion  into  the  coccyx,  and  vice  versa.  The 
great  sacro-sciatic  ligament  and  the  posterior  and  superior  sacro-iliac  ligaments  consti- 
tute a  fibrous  plane  in  the  shape  of  bundles,  arising  from  the  superior  posterior  spinous 
process  of  the  ilium,  and  extending  in  various  directions. 

fVg..  77,  The  small  sacro-sciatic  ligament  {m,figs.  76,  77),  placed  in 

front  of  the  preceding,  and  extremely  thin,  arises  from  the 
summit  of  the  spine  of  the  ischiimi,  passes  inward,  and, 
becoming  thinner,  is  lost  upon  the  anterior  surface  of  the 
great  sacro-sciatic  ligament.  The  two  sacro-sciatic  liga- 
ments divide  the  great  sacro-sciatic  notch  into  two  distinct 
foramina  :  the  upper  (n,  fig.  77)  is  very  large,  and  shaped 
like  a  triangle  with  the  angles  rounded  off,  and  is  in  a  great 
measure  filled  up  by  the  coccygeus  and  pyriformis  muscles ; 
it  gives  passage  also  to  the  great  and  small  sciatic  nerves, 
to  the  ischiatic  vessels,  and  to  the  gluteal  and  internal  pu- 
dic  vessels  and  nerves,  and  to  a  large  quantity  of  cellular 
tissue.  That  form  of  hernia  which  is  called  sciatic  takes 
place  through  this  foramen.  The  lower  {o,fig.  77)  is  much 
smaller ;  it  is  situated  between  the  spine  and  tuberosity  of 
the  ischium,  and  gives  passage  to  the  obturator  intemus 
muscle,  and  to  the  internal  pudic  vessels  and  nerves. 

Mechanism  of  the  Pelvis. 

The  mechanism  of  the  pelvis  should  be  regarded  in  four  distinct  points  of  view :  1. 
As  affording  protection  to  the  contained  viscera ;  2.  In  relation  to  the  part  which  it  per- 
forms in  the  mechanism  of  standing  and  progression  ;  3.  In  connexion  with  the  phenom 
ena  of  part  mtion ;  and,  4.  In  reference  to  the  motions  which  take  place  at  its  articula 
tions  with  other  bones,  and  those  between  its  own  component  parts. 

I.  Mechanism  of  the  Pelvis  considered  as  a  Protecting  Structure. — The  following  are  the 
conditions  in  the  structure  of  the  pelvis,  having  reference  to  its  ofiice  as  a  protector  of 
the  contained  viscera  :  1.  Behind ;  the  presence  of  the  sacrum,  which  is  itself  pi-otected. 


ARTICULATIONS    OP    THE    PELVIS.  ISV 

as  well  as  the  nerves  that  pass  through  it,  by  the  great  prominence  of  the  posterior  iliao 
tuberosities,  which  project  considerably  beyond  it ;  2.  On  the  sides,  by  the  crest  of  the 
ilium,  and  the  prominence  of  the  trochanters,  which  so  often  preserve  the  pelvis  from  ex- 
ternal violence.  With  regard  to  the  large  notch  in  front,  which  leaves  the  viscera  situ- 
ated on  a  level  with  it,  unprotected,  it  may  be  remarked,  that  the  viscera  contained  in  the 
small  pelvis,  being  liable  to  considerable  changes  of  volume,  require  to  leave  the  osseous 
and  unyielding  space  which  contains  them  when  empty,  in  order  that  they  may  extend 
into  a  cavity  the  walls  of  which  are  soft,  and  may  be  dilated  almost  indefinitely ;  3.  In 
front  the  means  of  protection  are  much  less  efficacious,  in  consequence  of  the  vast  notch 
which  is  situated  in  this  region. 

The  partial  absence  of  the  bony  parietes  in  front  has  reference  to  the  great  variation? 
in  size  which  the  viscera  of  the  pelvis  can  undergo,  and  which  would  have  been  incom- 
patible with  the  existence  of  an  osseous  cincture,  incapable  of  dilatation.  The  absence 
of  bony  walls  in  the  situation  of  the  three  great  notches,  presented  by  the  outlet  of  the 
pelvis,  is  also  unfavourable  to  its  solidity ;  but  it  has  many  other  important  uses,  partic- 
ularly in  the  mechanism  of  labour.  The  pelvis,  especially  at  its  upper  part,  where  it  is 
most  exposed  to  injury,  is  enabled  to  resist  external  violence  by  virtue  of  its  vaulted  con 
struction.  Part  of  the  impulse,  also,  is  lost  in  producing  the  slight  degree  of  gliding  mo 
tion  permitted  at  the  symphysis  pubis.  "Where,  however,  the  power  of  resistance  pos- 
sessed by  the  pelvis  is  overcome,  it  will  be  seen  at  once  that  the  parts  most  liable  to 
fracture  are  the  ascending  rami  of  the  ischia  at  their  junction  with  the  descending  rami 
of  the  ossa  pubis. 

2.  Mechanism  of  the  Pelvis  with  regard  to  Standing  and  Progression. — The  part  perform- 
ed by  the  pelvis  in  standing  is  connected  with  the  transmission  of  the  weight  of  tlie  trunk 
to  the  lower  extremities  ;  this  is  efFi>cted  by  means  of  "the  sacrum,  which  rests  upon  the 
ossa  innominata.  We  should  add,  that  a  small  portion  of  the  weight  is  directly  trans- 
mitted to  the  femurs  by  the  iliac  bones,  which  support  the  viscera  of  the  abdomen. 

TQbe  following  arrangements  should  be  noted,  as  being  concerned  in  the  transmission  of 
the  weight  by  means  of  the  sacrum :  1.  The  great  size  of  that  bone,  affording  evidence 
of  the  destination  of  man  for  the  erect  posture.  2.  The  obtuse  angle  at  which  the  sacrum 
unites  with  the  vertebral  column,  peculiar  to  the  human  species,  and  which  becomes  the 
seat  of  a  decomposition  of  the  force  transmitted  by  the  spine.  Part  of  the  momentum 
acting  in  the  direction  of  the  axis  of  the  column  has  no  other  effect  than  that  of  increas- 
ing the  sacro- vertebral  angle,  at  the  expense  of  the  flexibility  of  the  inter-articular  car- 
tilage ;  the  rest  is  transmitted  to  the  sacrum,  and  then  to  the  lower  extremities.  3.  The 
double  wedge  shape  of  the  sacrum  itself.  In  order  to  understand  the  advantage  arising 
from  this  form,  it  is  necessary  to  remark,  first,  that  the  weight  of  the  trunk  is  transmit- 
ted in  the  axis  of  the  upper  half  of  the  sacrum,  and,  consequently,  in  the  direction  of  a 
line  sloping  downward  and  backward  ;  from  this  it  follows,  that  the  sacrum  must  have 
a  tendency  to  be  displaced  either  downward  or  backward,  but  the  displacement  downr 
ward  is  prevented  by  the  position  of  the  ossa  innominata,  which  are  nearer  to  each  other 
below  than  above.  The  displacement  backward  is  obviated  by  the  oblique  direction  of 
the  articular  surfaces  of  the  same  bones  backward  and  inward,  while  the  obliquity  of  the 
sacrum  itself  is  in  the  opposite  direction,  for  it  is  broader  in  front  than  behind.*  4.  The 
distance  intervening  between  the  sacro-iliac  and  the  coxo-femoral  articulations.  The 
articulation  of  the  vertebral  column  with  the  pelvis  being  situated  at  the  back  part  of  that 
cavity,  while  those  of  the  femurs  are  situated  towards  the  front  and  the  side,  the  distance 
between  them  increases  the  space  in  which  the  centre  of  gravity  can  oscillate,  without 
being  carried  so  far  forward  as  to  pass  beyond  the  perpendicular  let  fall  from  the  coxo- 
femoral  articulation  to  the  base  of  support.  In  man  alone  is  found  a  large  pelvian  basis 
of  support,  and  thus  the  erect  posture  has  been  rendered  possible  in  him,  without  an  ex- 
cessive extension  in  front. 

In  quadrupeds,  the  antero-posterior  diameter  of  the  bones  of  the  ilium  is  rather  short, 
and  their  haunch  bones  are  elongated  behind,  and  placed  in  almost  the  same  plane  as 
the  vertebral  column.  The  foetus  and  new-born  infant  somewhat  resemble  the  lower 
animals  in  this  respect,  and,  therefore,  in  the  human  subject  there  is  a  great  tendency 
to  assume  the  attitude  of  a  quadruped  during  the  first  year  of  existence. 

The  weight  received  by  the  sacrum  and  transmitted  to  the  haunch  bones  is  divided, 
sometimes  equally  and  sometimes  unequally,  between  the  sacro-iliac  symphyses.  One 
portion  of  the  impulse  calls  into  action  the  mobility  of  the  symphyses,  and  the  remainder 
is  transmitted  to  the  cotyloid  cavities.  It  should  be  remarked,  that  this  transmission  is 
effected  along  the  triangular  prismatic  columns,  which  form  the  sides  of  the  inlet  of  the 
pelvis,  and  are  the  thickest  and  strongest  parts  of  that  structure.     At  the  foot  oi  these 

*  Without  admitting-  that  the  influences  to  which  the  sacrum  is  subjected  have  a  tendency  to  force  it  back- 
ward as  well  as  downward,  it  is  impossible  to  explain  either  the  use  of  its  being-  shaped  like  a  wedge,  with 
the  base  turned  forward,  or  of  that  powerful  apparatus  of  posterior  ligaments  which  can  oidy  resist  its  disloca- 
tion backward.  The  idea  that  these  forces  tend  to  press  it  forward  is  manifestly  at  variance  with  the  naturt 
of  the  uniting  media  ;  for  the  sacro-iliac  symphyses  are  only  maintained  in  front  by  a  very  thin  ligamentous 
layer,  and  the  breadth  of  the  space  between  the  iliac  bones  is  also  greater  in  front  than  behind;  ciicumstaa- 
ces  that  ■\\ould  evidently  facilitate  displacement  forward. 


ARTHROLOGY. 

columns,  which  form  cmres,  we  find,  dug,  as  it  were,  into  their  substances,  the  cotyloid 
cavities,  to  which  the  weight  of  the  trunk  is  transmitted.  During  the  sitting  posture,  the 
weight  of  the  body  is  transmitted  to  the  tuberosities  of  the  ischia,  which,  from  their  great 
size,  are  well  fitted  to  support  it.  As  these  processes  are  a  little  anterior  to  the  cotyloid 
cavities,  and,  therefore,  situated  in  a  plane  very  near  the  front  of  the  pelvis,  the  centre 
of  gravity  of  the  trunk  has  a  tendency  to  fall  behind  the  basis  of  support  represented  by 
them ;  and,  therefore,  it  is  easy  to  push  an  individual  backward  when  in  the  sitting  pos- 
ture, inasmuch  as  in  front  the  basis  for  the  support  of  the  pelvis  is  increased  by  the  length 
of  tlie  femurs  and  the  length  of  the  foot  while  man  is  seated  on  a  chair,  and  the  whole 
length  of  the  abdominal  extremity  while  he  is  seated  on  a  horizontal  plane.  The  mode 
in  which  the  pelvis  resists  violence  appUed  to  the  tuberosities  of  the  ischia  in  falls,  is  some- 
what connected  with  its  mechanism  as  adapted  to  the  sitting  posture.  The  shock  is,  in 
these  cases,  transmitted  directly  upward  in  the  dh-ection  of  the  acetabula,  the  lower  hem- 
ispheres of  which  offer  resistance  like  two  arches  :  from  the  acetabula  the  impulse  is 
communicated  backward,  by  the  thick  columns  extending  from  behind  these  cavities,  to 
the  sacro-iliac  symphyses  ;  and  forward,  to  the  symphysis  pubis  ;  so  that  falls  upon  the 
tuberosities  are  dmost  always  accompanied  with  painful  concussion  both  of  the  sacro- 
iliac and  pubic  symphyses. 

In  order  to  complete  our  account  of  the  mechanism  of  the  pelvis  in  standing,  we  must 
examine  its  mode  of  resistance  in  falls  upon  the  knees  or  soles  of  the  feet.  In  this  case, 
the  shock  is  communicated  from  below  upward  to  the  upper  halves  of  the  cotyloid  cavi- 
ties, wliich  are  supported  by  the  prismatic  columns  already  described.  The  anterior 
part  of  each  acetabulum  presents  a  large  notch,  and  is  altogether  unconcerned  in  the 
transmission  of  these  shocks  ;  so,  also,  is  the  very  thin  lamina  constituting  the  bottom  or 
inner  wall  of  the  cavity,  which  can  only  suffer  compression  in  falls  upon  the  great  tro- 
chanter. The  great  difference  existing  between  a  fall  upon  the  knees  and  the  tuberosi- 
ties of  the  ischia,  and  the  fall  upon  the  points  of  the  feet,  with  regard  to  a  commotion  of 
the  brain  and  the  spinal  marrow,  may  be  easily  conceived.  While  standing  on  one  4»ot 
the  weight  of  the  trunk  is  transmitted  to  the  femur  by  the  sacro-iliac  symphyses,  and  by 
the  curve-shaped  column  of  the  side  which  bears  upon  the  ground.  In  this  position  a 
fall  readily  takes  place,  on  account  of  the  facihty  with  which  the  centre  of  gravity  passes 
the  basis  of  support. 

During  progression,  the  pelvis  affords  to  each  thigh  alternately  a  solid  fulcrum,  and  re- 
ceives itself  a  fixed  point  of  support  from  the  femur  of  that  leg  which  rests  upon  the 
ground.  While  onp  side  of  the  pelvis  is  thus  supported  upon  one  of  the  thigh  bones,  the 
other  side  is  projected  forward.  These  alternate  movements  of  projection  of  either  side 
of  the  pelvis  take  place  at  the  coxo-femoral  articulation  of  the  extremity  which  rests 
upon  the  ground.  The  alternate  movements  of  projection  increase  in  proportion  to  the 
breadth  of  the  pelvis.  It  is  for  this  reason  that  women,  in  walking,  move  the  hips  more 
than  men.  The  remark  of  a  witty  author,  that  "  running  is  the  only  thing  which  women 
are  unable  to  do  gracefully,"  is  an  allusion  to  this  rather  awkward  motion  of  the  pelvis. 
We  may  form  a  correct  idea  of  the  share  which  the  pelvis  takes  in  the  act  of  walking  by 
studying  the  mode  of  progression  of  persons  with  wooden  legs.  In  these  unfortunate 
beings  the  lateral  inclinations  of  the  pelvis  are  sufficient  for  progression  by  transporting 
the  centre  of  gravity  alternately  to  the  two  inflexible  columns  substituted  for  the  lower 
extremities. 

3.  Mechanism  of  the  Pelvis  with  regard  to  Parturition.  —  The  art  of  midwifery  depends, 
in  a  great  measure,  upon  the  study  of  the  pelvis  ;  it  is  impossible  to  form  a  true  concep- 
tion of  the  mechanism  of  natural  labour  without  being  acquainted  with  the  axes  of  the 
pelvis,  its  dimensions  as  compared  with  the  size  of  the  foetus,  the  sacro- vertebral  angle, 
the  inclined  planes  of  the  true  pelvis,  the  diameters  of  the  brim  and  the  outlet,  and  the 
malformations  to  which  it  is  liable.  Any  lengthened  details  upon  these  points  would  be 
out  of  place  here.  I  shall  only  remark,  I.  That  the  existence  of  the  arch  of  the  pubes 
is  pecidiar  to  the  human  species ;  and,  2.  That  the  sciatic  notches  and  the  obturator 
foramina  are  not  only  useful  from  economizing  weight,  but  also  because,  corresponding 
as  they  do  to  the  oblique  diameters  of  the  head  of  the  foetus  during  parturition,  they  ren- 
der less  painful  the  pressure  attendant  upon  that  process ;  3.  That  the  pyramidales,  the 
mtemal  obturators,  and  the  psoae  and  iliaci  muscles  perform,  so  to  speak,  the  office  of  mat- 
tresses in  the  pelvic  cavity ;  4.  That  parturition,  consisting  in  the  expulsion  of  the  foetus 
along  the  line  of  the  pelvis,  natural  parturition,  provided  the  expulsive  power  exists  in 
its  normal  conditions,  depends  partly  on  a  true  conformation  of  the  pelvis,  and  partly  on 
a  true  conformation  and  position  of  the  foetus ;  5.  That  a  general  idea  of  all  the  defects 
which  may  occur  in  the  conformation  of  the  pelvis  may  be  expressed  by  stating,  that 
this  cavity  is  liable  to  all  the  malformations  which  may  result  from  a  pressure  upon  its 
whole  brim  or  only  a  part  of  it,  from  above  downward,  from  below  upward,  from  before 
backward,  or  from  side  to  side. 

4.  Mechanism  of  the  Pelvis  with  regard  to  its  own  Movements. — The  intrinsic  movements 
of  the  pelvis  are  very  obscure,  being  confined  to  mere  gliding  or  swinging  motions,  the 
production  of  which  destroys  part  of  the  momentum  from  any  external  violence.     By 


COXO-FEMOEAL   AETICULATION.  159i 

some  admirable  contrivance,  the  mobility  of  the  intrinsic  articulations  of  the  pelvis  is 
considerably  increased  during  the  latter  periods  of  pregnancy,  so  that  the  coccyx  may  be 
pressed  backward,  causing  an  increase  of  five  or  six  lines  in  the  antero-posterior  diam- 
eter of  the  outlet ;  wliile  the  symphysis  pubis*  becomes  susceptible  of  a  slight  separa- 
tion, which  increases  (in  a  very  slight  degree,  it  is  true,  but  sufficiently  to  merit  notice) 
the  dimensions  of  the  brim  of  this  cavity.  This  mobiUty,  which  is  especially  remarkable 
in  a  narrow  pelvis,  favours  the  process  of  labour  in  a  singular  degree.  The  natural  mobil- 
ity of  the  symphysis  pubis  has  suggested  the  operation  of  symphyseotomy,  by  which  the 
diameters  of  the  pelvis,  however,  are  but  little  increased,  unless  the  severing  of  the 
bones  of  the  pubes  should  be  carried  far  enough  to  result  in  a  separation  of  the  sacro- 
iliac symphysis.  A  relaxation  taking  place  in  the  symphysis  of  the  pelvis  may  give  rise 
to  strange  errors  in  diagnosis. 

The  extrinsic  movements  of  the  pelvis  are  those  of  flexion,  extension,  lateral  inclina- 
tion, and  rotation :  these  motions,  which  are  all  very  hmited,  have  been  indicated  in 
describing  the  mechanism  of  the  vertebral  column.  The  motions  of  the  pelvis  upon  the 
thighs  are  very  considerable  :  they  will  be  examined  with  the  mechanism  of  the  hip-joint. 

CoxO-FEMOEAL  ARTICULATION  {fig.  76). 

Preparation. — Remove  with  care  all  the  muscles  that  surround  the  joint,  preserving 
the  reflected  tendon  of  the  rectus  femoris.  The  psoas  and  iliacus  muscles,  the  synovial 
capsule  of  which  so  often  communicates  with  the  articular  synovial  membrane,  must  be 
removed  with  particular  care.  After  the  fibrous  capsule  has  been  studied  upon  its  exter- 
nal surface,  a  circular  division  should  be  made  round  its  middle  portion,  for  the  purpose 
of  uncovering  the  deep-situated  parts.  This  articulation  is  the  type  of  the  order  enar- 
throsis,  being  a  true  ball  and  socket  joint. 

The  articular  surfaces  are  the  globular  head  of  the  femur,  and  the  cotyloid  cavity  of  the 
OS  innominatum.  There  is  a  striking  difference  between  this  joint  and  that  of  the  shoul- 
der, as  far  as  regards  the  size  of  the  articular  head  and  the  depth  of  the  articular  cavity. 
While  the  head  of  the  humerus  and  the  glenoid  cavity  are  simply  in  juxtaposition  with- 
out any  reception  of  the  former  into  the  latter,  so  that  the  scapulo-humeral  articulation 
has  for  a  long  time  been,  and  is  now  considered  as  an  arthrodia,  there  is  a  deep  and  com- 
plete fitting  of  the  head  of  the  femur  into  the  cotyloid  cavity,  which  we  have  pronoun- 
ced to  be  the  deepest  articular  cavity  of  the  body.  Both  of  the  surfaces  above  named 
are  covered  with  cartilage,  with  the  exception  of  two  depressions,  one  of  which  is  situa- 
ted on  the  head  of  the  femur,  the  other  at  the  bottom  of  the  cotyloid  cavity  :  the  latter 
is  filled  with  a  reddish  adipose  tissue,  improperly  called  the  cotyloid  gland.  It  is  analo- 
gous to  the  adipose  tissue  found  in  the  neighbourhood  of  all  the  joints ;  its  use  is  not 
well  known.  I  have  often  asked  myself  the  question,  Why  should  there  be  this  poste- 
rior cotyloid  cavity !  On  submitting  the  joint  to  an  antero-posterior  vertical  section, 
shghtly  encroaching  on  the  margin  of  the  posterior  cotyloid  cavity,  it  will  be  seen  that 
the  object  of  this  cavity  is  to  protect  the  round  ligament  in  all  the  possible  positions  of 
the  head  of  the  femur  ;  and  that,  without  this  cavity,  the  round  ligament  could  not  have 
existed  \vithout  its  being  compressed  between  the  articular  surfaces.  Now,  as  the  intra- 
articular vessels  enter  this  cavity,  and  go  to  the  head  of  the  femur  along  the  round  lig- 
ament, it  is  not  impossible  but  that  the  exclusive  use  of  this  posterior  cotyloid  cavity 
should  be  to  protect  the  vessels  destined  to  the  head  of  the  femur,  and  that  the  round 
hgament  itself  should  have  no  other  use  than  to  support  these  vessels,  and  to  transmit 
them  to  the  head  of  the  femur.  The  cotyloid  adipose  tissue  does  not  seem  to  have  any 
other  object,  except  to  fill  the  empty  space  of  this  posterior  cavity. 

It  appears  to  me  that  the  round  ligament  of  the  coxo-femoral  articulation  of  the  poste- 
rior cotyloid  cavity  serves  the  same  purpose  as  the  space  between  the  condyles  of  the 
lower  end  of  the  femur  and  the  crucial  ligaments  of  the  knee-joint. 

Means  of  Union. — The  cotyloid  ligament  {n,  fig.  76).  This  band,  improperly  called  co- 
tyloid ligament,  is  attached  to  the  margin  of  the  acetabulum,  which  it,  as  it  were,  com- 
pletes ;  it  augments  the  depth  of  the  cavity,  and  renders  smooth  its  sinuous  and  notched 
circumference.  It  is  of  greater  size  at  the  notches  than  in  any  other  part :  by  its  means 
the  irregularities  of  the  edge  of  the  acetabulum  are  effaced,  and  the  deep-  notch  in  front 
and  below  is  converted  into  a  foramen  for  the  passage  of  vessels  to  the  fatty  tissue,  the 
inter-artiailar  ligament,  and  the  head  of  the  femur. 

The  cotyloid  band  is  much  thicker  above  and  behind  than  below  and  in  front,  and  it 
is  precisely  against  the  first  two  points  that  the  head  of  the  femur  constantly  presses. 
It  is  also  remarkable,  in  this  respect,  that  the  diameter  of  its  free  borders  is  smaller  than 
that  by  which  it  is  attached ;  and  this  circumstance  assists,  in  some  degree,  in  retaining 
the  head  of  the  femur  in  the  cotyloid  cavity,  t    It  consists  of  fibres  which  arise  succes- 

*  In  a  female  seventy-nine  years  of  age,  the  mother  of  nineteen  children,  I  found  the  symphysis  pubis  ex- 
tremely movable  :  the  two  articular  surfaces  of  the  pubes  were  contiguous ;  the  interosseous  ligament  had 
disappeared  ;  and  a  very  thick,  fibrous  capsule,  of  recent  formation,  surrounded  the  articular  surfaces  in  front, 
above  and  below,  being  inserted  at  some  distance  from  them.    It  was  a  symphysis  changed  to  a  loose  arthrodia. 

t  I  have  never  seen  this  disposition  better  exhibited  than  in  a  subject  in  which  the  cotyloid  band  was  OSM- 
fied  in  its  whole  extent,  except  at  the  place  on  a  level  with  the  anterior  and  inferior  notch.    The  head  of  thfl 


160  ARTHROLOGY. 

sively  from  all  points  of  the  circumference  of  the  acetabulum,  and  interlace  at  very  acute 
angles.  This  interlacement  is  especially  visible  in  the  situation  of  tlie  great  anterior 
notch,  where  the  fibres  may  be  seen  arising  from  each  side  of  the  notch,  and  passing 
across  each  other. 

The  orUcular  ligament,  or  Jibrous  capsule  (p,  Jig.  76).  This  represents  a  fibrous  sac, 
having  two  openings,  by  one  of  which  it  embraces  the  acetabulum,  outside  the  cotyloid 
ligament,  while  the  other  surrounds  the  neck  of  the  femur.  The  femoral  insertion  of 
the  capsular  ligament  requires  to  be  carefully  studied,  for  the  purpose  of  explaining  the 
difference  between  fractures  within,  and  fractures  beyond,  the  capsule.  This  insertion 
is  so  arranged,  that  at  the  upper  part  and  in  front  of  the  joint  it  corresponds  with  the 
base  of  the  neck  of  the  femur,  while  beneath  and  behind  it  is  situated  at  the  junction  of 
the  external  wich  the  two  internal  thirds  of  the  neck.  The  insertion  of  the  capsule  in 
front  takes  place  not  only  at  the  base  of  the  neck  of  the  femur,  but  also  internally  to  this 
base,  to  the  extent  of  several  lines,  as  may  be  ascertained  by  an  incision  being  made 
along  this  insertion  in  the  direction  of  the  axis  of  the  neck.  The  length  of  tlie  orbicular 
ligament  is  exactly  equal  to  the  distance  between  its  insertions,  excepting  at  the  inner 
part,  where  it  is  much  more  loose.  Hence  the  extent  of  the  motion  of  abduction,  which 
is  so  remarkable  in  some  jugglers,  that  they  are  able  to  separate  their  legs  until  they 
form  right  angles  with  the  body,  without  producing  dislocation. 

The  thickness  of  this  ligament  is  not  equal  throughout :  it  is  greatest  above  and  on 
the  outside,  where  the  reflected  tendon  of  the  rectus  muscle  is  situated ;  it  is  yet  very 
considerable  in  front  and  above  ;  it  is  less  thick  behind,  and  still  thinner  on  the  inside. 
In  some  subjects  the  thickness  of  the  superior  part  of  the  capsule  is  to  that  of  the  inferi- 
or as  five  to  one.  In  front,  the  capsule  is  strengthened  by  a  bundle  of  fibres  stretched 
Dbliquely,  like  a  sling,  from  the  anterior  inferior  spinous  process  of  the  ilium  to  the  inside 
of  the  base  of  the  neck  of  the  femur.  It  is  called  by  Bertin  the  anterior  and  superior  lig- 
ament (r,  fig.  76).  This  band,  which  serves  as  a  re-enforcement  to  the  capsule,  lies  un- 
der that  portion  of  the  iliacus  muscle  which  arises  from  the  anterior  spinous  process  of 
the  ilium,  and  follows  the  direction  of  this  muscle ;  it  is  composed  of  pardlel  fibres,  and 
closely  adheres  to  the  capsule,  without  adhering  in  the  least  to  the  muscle.  Within  this 
bundle  the  capsule  is  often  imperfect,  and  permits  a  communication  between  the  synovial 
membrane  of  the  joint  and  the  bursa  of  the  psoas  and  iliacus  muscles.  This  last  syno- 
vial membrane  may  be  considered  as  a  prolongation  of  the  articular  synovial  membrane  ; 
this  prolongation  is  analogous  to  the  one  which  we  have  described  at  the  scapulo-hume- 
ral  articulation  for  the  subscapularis  muscle.  In  one  subject  that  I  dissected,  the  com- 
municating orifice  was  so  large,  that  the  common  tendon  of  these  muscles  was  in  imme- 
diate contact  with  a  considerable  portion  of  the  head  ofthe  femur ;  the  tendon  itself  be- 
ing split  into  several  bands,  some  of  which  had  been  lacerated,  and,  as  it  were,  worn 
away  by  friction. 

The  external  surface  of  the  capsular  ligament  is  in  relation  with  the  psoas  and  iliacus 
muscles  in  front,  being  separated  from  them  by  a  bursa  at  the  upper  part,  in  those  cases 
where  the  fibrous  capsule  is  not  interrupted,  and  giving  insertion  to  many  of  their  fibres 
below.  On  the  inside,  it  is  in  relation  with  the  obturator  externus  and  the  pectineus  ; 
on  the  outside,  with  the  gluteus  minimus  ;  behind,  with  the  quadratus  femoris,  the  ge- 
melli,  the  pyi-iformis,  and  the  obturator  intemus.  Several  of  these  muscles  send  fortify- 
ing bundles  of  fibres  to  the  capsule.  I  may  point  out  an  aponeurotic  expansion  coming 
from  the  gluteus  minimus,  which  establishes  a  close  connexion  between  this  muscle  and 
the  capsule ;  a  second  expansion,  furnished  by  the  pyriformis  and  the  gemelli ;  and  a  third, 
which  is  furnished  to  the  capsule  by  the  tendon  of  the  vastus  externus.  The  internal 
surface  is  lined  by  the  synovial  membrane. 

The  orbicular  ligament  ofthe  hip-joint  differs  from  the  generality  of  such  structures 
in  being  of  a  dull  white  instead  of  a  pearly  white  colour,  and  in  being  composed  of  ir- 
regularly interlaced  fibres,  except  the  superficial  fibres,  which  are  disposed  in  parallel 
lines.  I  have  also  observed  a  very  remarkable  fact,  apparently  overlooked  by  anatomists, 
viz.,  that  it  is  extremely  thin  at  its  inferior  orifice,  but  especially  behind ;  and  that  near 
this  insertion  it  is  strengthened  by  some  circular  fibres  which  embrace  the  neck  of  the 
bone  like  a  collar,  but  without  adhering  to  it ;  and  that  in  its  different  movements  this 
sort  of  collar  rolls  round  the  neck,  but  is  retained  in  its  place  by  small  bundles  of  fibres, 
reflected  from  the  capsule  upon  the  neck  of  the  bone,  which  raise  the  synovial  mem- 
brane from  the  surface. 

The  intcr-articular,  which  is  improperly  called  round  ligament  (t,  fig.  76).  This  ligament 
arises,  under  the  form  of  a  fibrous  band,  folded  backward  upon  itself,  from  the  depression 
on  the  head  of  the  femur,  which  depression  is  not  entirely  filled  by  it.  It  is  twisted 
around  this  head,  and  is  divided  into  three  bands,  one  of  which,  after  having  again  been 
subdivided,  traverses  the  adipose  tissue  and  is  fixed  into  the  bottom  of  the  cotyloid  cav- 
ity, while  the  two  others  are  attached  to  the  two  edges  ofthe  cotyloid  notch,  below  the 
cotyloid  band,  by  which  this  insertion,  with  which  it  is  often  continuous,  is  concealed. 

femur  wis  mechanically  and  solidly  retained  in  the  acetabulum,  whose  bottom,  being  partly  worn  out  ani] 
pressed  inward,  fonned  a  prominence  in  the  interior  face  of  the  pelvis. 


COXO-FEMORAL   ARTICULATION.  161 

In  one  case  a  prolongation  of  this  ligament  traversed  the  cotyloid  notch,  and  was  at- 
tached to  the  part  nearest  the  capsule.  The  thickness  and  the  strength  of  this  inter-ar 
ticular  ligament  are  extremely  variable :  sometimes  it  is  extremely  strong,  sometimes  very 
weak ;  sometimes  it  adheres  to  one  edge  only  of  the  notch ;  sometimes  it  consists  mere- 
ly of  a  few  ligamentous  fibres,  contained  within  the  substance  of  the  reflected  synovial 
membrane  ;  sometimes  in  its  place  is  found  a  fold  of  that  membrane,  which  may  be  torn 
by  the  slightest  force ;  and,  lastly,  it  is  not  uncommon  to  find  that  it  is  altogether  wanting. 
The  synovial  membrane  lines  the  whole  internal  surface  of  the  capsular  ligament  the 
two  non-adhering  surfaces  of  the  cotyloid  ligament,  and  that  part  of  the  neck  of  the  fe- 
mur contained  within  the  joint ;  it  embraces  the  round  ligament,  and  sends  off  a  pro- 
longation from  it  to  a  quantity  of  fatty  matter  at  the  bottom  of  the  acetabulum;*  an  ar- 
rangement which  led  the  older  anatomists  to  believe  that  the  round  ligament  was  in- 
serted into  the  bottom  of  the  cotyloid  cavity. 

Mechanism,  of  the  Coxo-femoral  Articulation. 

Like  all  enarthroses,  the  coxo-femoral  articulation  can  execute  movements  of  flexion, 
extension,  abduction,  adduction,  circumduction,  and  rotation. 

1.  Inflexion,  the  head  of  the  femur  roUs  in  the  cotyloid  cavity  around  an  imaginary 
axis  corresponding  with  that  of  the  neck  of  the  bone,  while  the  lower  end  of  the  femur 
is  carried  from  behind  forward,  and  describes  the  segment  of  a  circle,  whose  radius  is 
represented  by  the  shaft  of  the  bone.  In  the  mechanism  of  this  movement,  the  neck  of 
the  femur  has  the  effect  of  substituting  a  rotatory  motion  of  the  head  of  that  bone  upon 
a  fixed  point,  without  changing  the  relation  of  the  head  with  the  acetabulum,  and,  con- 
sequently, without  any  tendency  to  displacement,  for  a  very  extensive  movement  back- 
ward and  forward,  which  would  otherwise  have  been  necessary,  and  in  which  the  sur- 
faces would  have  been  liable  to  separation  from  each  other.  We  can,  indeed,  scarcely 
believe  that  luxation  would  be  possible  during  this  motion,  although  it  can  be  carried  so 
far  that  the  front  of  the  thigh  and  the  fore  part  of  the  abdomen  may  be  brought  in  contact 

2.  Extension  is  effected  by  the  same  mechanism,  the  head  and  the  neck  of  the  femur 
rolling  upon  themselves  from  behind  forward,  while  large  arcs  of  a  circle,  from  before 
backward,  are  described  by  the  body  of  the  bone  ;  but  such  is  the  obliquity  of  the  acetab- 
ulum, which  looks  both  forward,  outward,  and  downward,  that  when  the  femur  is  in  the 
vertical  direction,  the  head  projects  and  carries  forward  the  fibrous  capsule.  The  anterior 
re-enforcing  bundle  is  stretched.  The  psoas  and  iliacus  muscles  perform  the  office  of  an 
active  ligament.  Luxations  of  the  femur  forward  are  not  common,  for  the  movement  of 
extension  is  limited  by  the  meeting  of  the  edge  of  the  acetabulum  and  the  back  part  of  the 
neck  of  the  femur ;  and  the  ligament  and  muscles  above  named  also  tend  to  counteract  it. 

3  and  4.  The  mechanism  of  adduction  and  abduction  is  altogether  different  from  that 
of  the  preceding  movements,  where  the  articulation  forms  the  centre  of  a  circle  descri- 
bed by  the  femur,  the  radius  of  which  is  measured  by  a  line  stretched  from  the  head  of 
the  bone  to  the  space  between  the  condyles.  In  abduction,  the  head  of  the  femur  presses 
against  the  inner  part  of  the  capsular  ligament ;  and,  on  account  of  the  looseness  of  this 
ligament,  the  obliquity  of  the  acetabulum,  and  the  arrangement  of  the  inter-articular  lig- 
ament, this  movement  may  be  carried  very  far  without  displacement,  and  is  only  limited 
by  the  meeting  of  the  upper  edge  of  the  neck  of  the  femur  with  the  rim  of  the  cotyloid 
cavity.  But  this  very  niceting  may  itself  become  the  cause  of  luxation,  and  then  the 
edge  of  the  cotyloid  cavity  may  be  regarded  as  the  fulcrum  of  a  lever  of  the  first  order 
with  unequal  arms,  the  whole  length  of  the  femur  being  the  arm,  to  which  the  power  is 
applied,  and  the  neck  of  the  bone,  that  by  which  the  resistance  acts. 

In  adduction,  the  femur  moves  in  precisely  the  opposite  direction  :  this  motion  is  lim- 
ited by  the  mutual  contact  of  the  two  thighs,  but,  by  means  of  slight  flexion,  it  may  be 
carried  so  far  as  to  throw  one  over  the  other.  The  great  depth  of  the  upper  and  exter- 
nal part  of  the  cotyloid  cavity,  and  the  strength  of  the  capsular  ligament  in  the  same  di- 
rections, would  seem  to  oppose  all  displacement.  But  it  should  be  observed,  that  falls 
upon  the  knees  almost  always  happen  during  adduction  of  the  thighs,  for  this  is  an  in- 
stinctive movement  of  preservation.  However  slight  the  adduction  may  be,  the  inter- 
articular  ligament  is  of  necessity  stretched ;  and  from  this  it  follows,  as  my  colleague, 
M.  Gerdy,  has  ingeniously  remarked,  that  the  head  of  the  femur  is  detached  from  the 
bottom  of  the  cavity  by  a  kind  of  rolling  of  the  round  ligament  upon  it,  and  comes  to 
press  against  the  fibrous  capsule.  The  rupture  of  the  inter-articular  ligament  is  not  al- 
ways necessary  in  luxation.  I  have  seen  several  instances  of  a  so-called  incomplete  lux- 
ation inward,  without  this  hgament  being  torn. 

5.  Circumduction  consists  in  the  transition  from  one  of  these  motions  to  another.   The 

*  The  synovial  membrane  is  often  seen,  being  interposed  and  descending-  between  the  adipose  substance 
and  the  posterior  cotyloid  cavity.  I  may  also  point  out  semilunar  folds,  which  are  often  formed  by  tne  syno 
rial  membrane  round  the  neck  of  the  femur.  These  folds  are  supported  by  some  detached  fibres  of  the  cap- 
Bule,  so  that  the  neck,  on  a  level  with  those  fibres,  is  lined  with  synovial  membrane  only  in  the  neighbour 
hood  of  the  head  of  the  femur.  The  synovial  folds  appear  to  me  destined  to  conduct  vessels  to  the  margin  of 
the  head  of  the  femur.  Round  the  head  of  the  femur,  at  its  point  of  union  with  the  neck,  are  constants 
found  very  small  adipose  bundles.  v     •  -  •    • 

X 


162  '  "'  '    ■   ARTHROLOGY. 

femur  circumscribes  a  cone,  of  which  the  apex  is  in  the  joint,  while  the  base  is  described 
by  the  lower  end  of  that  bone.  The  axis  of  the  cone  is  represented  by  aline  drawn 
from  the  head  of  the  femur  to  the  interval  between  the  condyles  ;  and  the  length  of  the 
femur  accounts  for  movements  which  are  scarcely  felt  at  the  coxo-femoral  articulation, 
being  so  considerable  at  the  lower  end  of  the  bone. 

6.  Independently  of  the  movements  above  described,  the  coxo-femoral  articulation  per- 
forms motions  of  rotation,  arising  by  no  means  from  its  enarthrodial  shape,  but  from  the 
presence  of  the  neck  of  the  femur.  Generally  no  movement  appears  to  require  a  greater 
expenditure  of  power  on  the  part  of  nature  than  the  rotatory  movements,  and  these  move- 
ments are  not  always  regulated  by  the  same  mechanism.  We  have  already  seen  an  ex- 
ample of  this  movement  in  the  atlo-axoidian  articulation,  where  a  cylinder  forme  1  by  tho 
odontoid  process  rolls  in  the  partly  osseous  and  partly  fibrous  ring  of  the  atlas,  as  an  axle 
tree  in  a  wheel.  Here  the  arrangement  is  quite  different ;  the  rotatory  movement  is  ob 
tained  simply  by  the  lever  being  bent  like  an  elbow  in  such  a  manner  as  to  make  the  rota 
tory  movements  of  the  femur  upon  its  axis  result  from  the  movements  forward  or  backward 
of  the  bent  portion.  This  movement  should  be  studied  both  at  the  upper  and  at  the  lower 
part  of  the  femur.  At  the  upper  part  it  is  a  motion  of  horizontal  displacement,  the  radi- 
us being  represented  by  the  head  and  neck  of  the  bone  ;  at  the  lower  part  it  is  a  rotatory 
motion  of  the  femur,  not  precisely  upon  itself,  but  upon  an  imaginary  axis  placed  on  the 
inside  of,  and  parallel  to,  the  shaft.  It  follows  that  there  can  be  no  rotation  in  cases  of 
fracture  of  the  neck  of  the  bone,  and  this  is  one  of  the  diagnostic  signs  of  that  accident 
Lastly,  it  may  be  observed  that  rotation  is  perfonned  from  without  inward,  or  from  within 
outward :  the  latter  is  the  more  extensive  and  more  natural  movement ;  it  is  produced  by 
a  great  number  of  muscles,  and,  therefore,  during  repose,  the  point  of  the  foot  is  slightly 
inclined  outward. 

The  Knee-joint  (Jigs.  78  to  81). 
Preparation. — 1.  Make  a  crucied  incision  in  front  of  the  knee  and  dissect  back  the  flaps. 

2.  Detach  the  aponeurosis  of  the  thigh,  preserving  the  fibrous  band,  which  forms  the  con- 
tinuation of  the  tensor  vagina  femoris,  and  which  forms,  as  it  were,  a  superficial  ligament. 

3.  Remove  the  aponeurosis  of  the  triceps  on  the  sides  of  the  patella,  taking  care  to  avoid 
opening  the  synovial  capsule.  4.  Remove  the  tendon  of  the  biceps,  and  turn  downward 
the  tendons  of  the  sartorius,  gracilis,  and  semitendinosus.  5.  Remove  the  popliteal  ves- 
sels and  nerves  behind,  and  also  the  gastrocnemii.  6.  After  having  studied  the  ligaments 
situated  around  the  synovial  capsule,  isolate  the  latter  as  much  as  possible  by  dissecting 
off  the  lateral  ligaments,  and  the  ligamentum  patellae.  7.  Open  the  synovial  capsule 
above  the  palate.  8.  Make  a  horizontal  section  of  the  femur  immediately  above  the  con- 
dyles, and  a  vertical  section  from  before  backward  between  the  condyles  These  two 
sections  are  intended  to  expose  the  crucial  ligaments. 

The  articulation  of  the  knee  belongs  to  the  class  of  angular  ginglymi ;  it  is  the  largest 
and  most  complicated  joint  in  the  human  body  ;  it  is,  perhaps,  the  most  important,  both 
in  regard  to  the  part  which  it  plays  in  the  mechanism  of  the  animal  economy,  and  the  fre- 
quency and  the  gravity  of  the  maladies  which  it  is  liable  to. 

Articular  Surfaces. — The  lower  end  of  the  femur  and  the  upper  end  of  the  tibia  are  the 
essential  constituents  of  this  joint,  which  is  completed  in  front  by  the  patella.  The  ar- 
ticular surface  of  the  femur  is  formed  in  front  by  the  trochlea,  and  behind  by  the  two 
condyles,  separated  by  the  intercondyloid  fossa  ;  the  articular  surface  of  the  tibia  con- 
sists of  the  glenoid  cavities,  separated  by  the  spine  of  the  til)ia,  in  front  of  and  behind 
which  are  some  irregular  projections.  The  patella  presents  two  concave  surfaces,  sep- 
arated from  each  other  by  a  vertical  ridge  corresponding  to  the  groove  of  the  trochlea. 
These  surfaces  are  aU  covered  with  a  thick  layer  of  cartilage.  It  should  be  remarked, 
with  regard  to  the  knee-joint,  1.  That  the  articular  surfaces  are  rather  placed  in  juxta- 
position than  jointed  together  ;  2.  That  the  articulation  is  in  some  measure  double,  since 
two  very  distinct  condyles  correspond  to  two  equally  distinct  cavities.  These  two  con- 
dyles being  turned  in  opposite  directions,  viz.,  the  external  backward  and  outward,  the 
internal  backward  and  inward,  they  are  opposed  to  each  other  ;  like  the  articulation  oi 
the  two  condyles  of  the  occipital  bone  with  the  atlas,  which  are  opposed  both  to  the  lat- 
eral and  the  rotatory  motions,  and,  in  regard  to  these  motions,  constitutes  an  angulai 
ginglymus,  so  in  the  case  in  the  knee,  its  two  condyles  constituting,  as  it  were,  a  double 
condylian  articulation,  transformed  into  an  angular  ginglymus. 

Inter-articular  Cartilages. — Like  all  joints  that  are  exposed  to  much  pressure,  the  knee 
is  provided  with  inter-articular  cartilages.  They  are  two  in  number,  and  are  named, 
from  their  figure,  semilunar  or  falciform  cartilages  (a,  b,  fig.  78).  Their  upper  surfaces, 
corresponding  to  the  convexity  of  the  condyles,  are  concave  ;  their  external  circumfer- 
ence is  very  thick,  and  the  internal  sharp  and  thin  :  they  therefore  assist  in  deepening 
the  concave  surfaces  of  the  tibia.  The  section  of  tlicse  cartilages  forms  an  elongated 
isoscele  triangle,  with  its  base  outward.  The  external  inter-articular  cartilage  (a)  gov 
ers  almost  the  whole  of  the  external  glenoid  cavity  of  the  tibia,  fonning  nearly  a  com- 
plete circle ;  while  the  internal  cartilage  (4),  which  is,  indeed,  semilunar,  leaves  a  great 


ARTICULATIONS   OP    THE    KNEE-JOINT. 


'-.H^'UnMt* . 


1^.78. 


part  of  the  corresponding  cavity  uncovered.*  In  this  respect 
the  inter-articular  cartilages  of  the  knee  differ  from  all  others 
of  the  S2uiie  kind,  for  they  do  not  establish  a  complete  separ- 
ation of  the  articular  surfaces,  between  which  they  are  placed. 
« hese  falciform  cartilages  are  inserted  into  the  tibia  by  means 
of  ligaments,  which  deserve  a  particular  description. 

Ligaments  of  the  External  Semilunar  Cartilage. — These  are 
two  :  the  one  anterior,  and  the  other  posterior  ;  both  of  them 
are  very  strong.  The  anterior  is  inserted  in  front  of  the  spine 
of  the  tibia,  outside  of  the  anterior  crucial  ligament,  into  a 
deep  depression  situated  near  the  external  glenoid  cavity  of 
the  tibia.  This  anterior  ligament  of  the  external  semilunar 
cartilage  sends  off  a  bundle  which  intermingles  with  the  ante- 
rior crucial  ligament.  The  posterior  is  inserted  into  the  spine 
of  the  tibia,  in  the  unequally-divided  interval  situated  between 
the  two  prominences  of  the  spine.  The  posterior  ligament 
sends  off  a  considerable  bundle  of  fibres  to  be  inserted  into  the 
posterior  crucial  ligament.  The  circular  form  of  the  external 
semilunar  cartilage  is  owing  to  the  insertions  of  the  two  an- 
teiior  and  posterior  ligaments  being  separated  from  each  other 
only  by  a  few  lines. 

Ligaments  of  the  Internal  Semilunar  Cartilage. — These  are  much  weaker  than  the  foi- 
mer.  The  anterior  is  inserted  a  good  deal  before  its  fellow,  the  anterior  ligament  of 
the  external  semilunar  cartilage,  and  the  posterior  is  inserted  a  good  deal  behind  the 
corresponding  ligament  of  the  externed  semilunar  cartilage  ;  hence  the  semilunar  shape 
of  the  internal  semilunar  cartilage,  which  does  not  send  off  any  fibrous  prolongation  to 
the  anterior  or  posterior  crucial  ligaments.  The  ligaments  of  the  inter-articular  cartila- 
ges being  inserted  into  the  tibia,  these  cartilages  follow  the  tibia  throughout  its  course 
Means  of  Union  of  the  Knee-joint  are  two  lateral  hgaments,  a  posterior  and  an  anterior, 
two  crucial  ligaments,  and  a  synovial  capsule. 
1.  Lateral  Ligaments. — The  external  lateral  ligament  {a,  figs.  79  and  80)  appears  as  a 


rounded  cord ;  it  is  inserted  into  the  exter- 
nal tuberosity  of  the  femur,  at  the  point  of 
union  of  the  five  anterior  sixths  with  the  first 
posterior,  on  the  prolongation  of  the  line  of 
the  fibula  ;  the  precise  point  of  this  insertion 
is  a  small  eminence  surmounting  a  depression 
which  is  destined  to  the  tendon  of  the  popli- 
teus  muscle,  and  is  situated  in  front  of  an-  al 
other  depression  destined  to  the  external  ge-  A 
meUus  ;  thence  this  ligament  descends,  in  a  '^ 
vertical  line,  to  be  inserted  into  the  external 
face  of  the  head  of  the  fibula.  This  ligament 
has  the  appearance  of  a  tendon ;  it  extends 
along  the  anterior  border  of  the  tendon  of  the 
biceps,  with  which  it  may  be  readily  con- 
founded. 

We  should  have  but  an  incomplete  idea  of 
the  means  of  union  which  the  knee-joint  pos- 
sesses on  the  outside,  if  we  did  not  add  to  the 
number  of  its  ligaments  the  tendon  of  the  bi- 
ceps, which  unites  in  some  sort  its  inferior 
insertions  with  those  of  the  external  lateral 
ligament,  and  the  small  band  of  the  fascia 
lata  inserted  into  the  anterior  tubercle  of  the 
tibia,  and  sending  to  the  external  edge  of  the 
rotula  an  expansion,  which  unites  with  the 
tendon  of  the  vastus  externus. 

The  internal  lateral  ligament  (J  c,  figs.  79 
and  80),  which  is  much  longer  than  the  exter- 
nal, has  the  shape  of  a  broad,  thin,  pearly- 
coloured  band,  arising  from  the  posterior  part 


Fig.  79. 


Fig.  80. 


*  On  asking-  myself  the  question  why  there  should  be 
this  difference  between  the  two  semilunar  cartilages,  I 
have  come  to  the  conclusion  that  the  external  condyle  of 
the  femur,  pressing  much  more  upon  the  tiliia  than  the 
internal,  on  account  of  the  external  following  the  axis 

of  the  femur,  while  the  internal  is  turned  away  from  it  ,  t.      »»■     l  f         ♦ 

to  the  inside,  the  externa!  inter-articular  cartilage  had  to  protect  a  greater  portion  of  the  articular  «unace  ol 
thti  tibia 


164  ARTHROLOGY. 

of  the  internal  tuberosity  of  the  femur,  on  a  level  with  the  external  lateral  ligament,  im- 
mediately below  the  tubercle  into  which  the  third  adductor  muscle  is  inserted ;  it  is 
turned  downward,  and  a  little  outward  ;  it  widens  in  its  course,  and  is  inserted,  by  a 
broad  surface,  into  the  internal  border  and  the  anterior  surface  of  the  tibia  :  at  this  in- 
sertion, which  is  at  least  an  inch  wide,  it  is  covered  by  the  tendons  of  the  sartorius^ 
gracilis,  and  semitendinosus  muscles,  which  glide  over  this  ligament  by  means  of  an  in 
tervening  synovial  bursa. 

Its  deep  surface  is  applied  to  the  anterior  or  reflected  tendon  of  the  semi-membrano 
sus,  to  the  internal  semilunar  cartilage,  to  which  it  intimately  adheres,  and  to  the  inter 
nal  inferior  articular  vessels,  which  are  protected  by  it. 

When  the  layers  of  this  ligament  are  removed  in  succession,  it  will  be  seen  that  the 
deepest  fibres  are  attached  to  the  superior  part  of  the  internal  tuberosity  of  the  tibia, 
and  adhere  to  the  synovial  membrane.  The  lateral  ligaments  are  situated  much  nearer 
to  the  flexing  or  the  back  part,  than  to  the  extending  or  the  fore  part  of  the  joint,  so 
that  they  are  stretched  during  extension,  and  assist  in  limiting  that  motion,  but  are  re- 
laxed during  flexion,  to  the  performance  of  which  they  offer  no  obstacle. 

The  posterior  ligament,  or  ligament  of  Winslow  (c,  figs.  79  and  81),  is  much  complicated, 
and  is  composed,  1.  Of  a  fibrous  capsule  for  each  condyle  ;  2.  Of  a  median  posterior  hg- 
ament,  the  only  one  which  has  been  described  by  authors. 

1.  Fibrous  Capsule  of  the  Cmidyles. — Each  condyle  is  enveloped  with  a  fibrous  husk  , 
that  of  the  external  condyle  is  covered  by  the  external  origin  of  the  gemellus,  and  thai 
of  the  internal  condyle  by  the  internal.  The  fibrous  capsule  of  the  internal  condyle  is 
completed  by  the  internal  origin  of  the  gemellus  turning  around  the  highest  and  most  in- 
ternal portion  of  this  condyle.  The  semi-membranosus  muscle  sends  a  fibrous  expansion 
from  above  downward  to  this  same  internal  capsule  ;  the  external  head  of  the  gemellus 
is  still  much  more  than  the  internal  identified  wath  the  corresponding  fibrous  capsule, 
which  furnishes  a  great  number  of  insertions  to  that  muscle.  When  there  is  a  sesa- 
moid bone  in  the  external  gemellus,  it  is  found  in  the  substance  of  the  external  capsule. 

2.  The  Median  Posterior  Ligament. — It  is  composed  of  several  sets  of  fibres  :  1.  Some 
pass  obliquely  upward  and  outward,  being  formed  by  a  considerable  expansion  of  the 
semi-membranosus ;  2.  Others  proceed  from  the  tendons  of  the  popliteus  and  the  ge- 
melli ;  and,  lastly,  3.  Some  fibrous  bundles,  partly  vertical  and  partly  oblique,  arise  from 
above  the  condyles  of  the  femur,  and  are  attached  to  the  tibia.  Frotn  this  collection  of 
fibres  running  in  different  directions,  there  results  an  irregularly-interwoven  ligament, 
perforated  by  foramina  that  transmit  the  ramifications  of  tlie  middle  articular  artery ; 
several  of  the  most  deeply-seated  ligamentous  bundles  are  inserted  into  the  edges  of 
the  inter-articular  cartilages. 

3.  Anterior  Ligament,  or  Ligamentum  Patellm  {d,figs.  80  and  81). — This  name  is  given 
to  that  portion  of  the  tendon  of  the  extensor  muscles  which  ex- 
tends from  the  patella  to  the  tibia.  This  ligament  has  the  thape 
of  a  very  broad,  thick,  almost  triangular  band.  Its  fibres  arise 
by  a  broad  insertion,  of  from  five  to  six  lines,  from  the  apex  of 
the  patella  and  from  the  anterior  surface  of  this  bone  ;  they  are 
parallel,  pearly-white,  and  become  nearer  to  each  other  as  they 
approach  the  most  prominent  and  lower  portion  of  the  anterior 
tuberosity  of  the  tibia,  to  which  tuberosity  they  are  attached.  It 
should  be  remarked,  tliat  this  ligament  is  by  no  means  inserted 
into  the  rugged  projections  which  are  found  on  the  back  part  of 
the  apex  of  the  patella.  Behind  this  ligament  is  a  considerable 
mass  of  adipose  tissue  {e,fig.  81),  which  separates  the  hgament 
from  the  articular  synovial  capsule  ,  a  synovial  bursa  if,  fig.  81) 
separates  it  from  the  anterior  portion  of  the  tuberosity  over 
which  it  glides.  This  synovial  bursa  sometimes  communicates 
with  the  articular  synovial  capsule,  and  sometimes  is  totally  dis- 
tinct from  it.* 

Crucial  or  Interosseous  Ligaments. — In  the  interior  of  the  knee- 

*  I  should  remark  that  this  bursa  extends  partly  over  the  ligament,  which  it  covers  from  side  to  side,  ana 
partly  over  the  anterior  tuberosity  of  the  tibia,  vfhich  is  at  this  point  completely  deprived  of  inter-articular  car. 
tilage  ,  so  that  the  facility  with  which  the  synovial  membrane  of  the  tibia  is  removed  contrasts  with  the  diffi- 
culty which  is  experienced  in  dissecting  the  synovial  membrane  which  covers  the  inter-articular  cartilages, 
provided  it  exists  there.  The  ligamentum  patella;  forms  only  a  part  of  the  anterior  ligament  of  the  knee-joint , 
this  anterior  ligament  is  completed  by  the  rotula  and  by  the  united  tendons  of  the  rectus  femoris,  the  vastus 
mtemus  and  extemus,  of  which  united  tendons  the  ligamentum  patellae  is  evidently  a  continuation.  We  see 
here  a  very  remarkable  application  of  this  law,  by  mea>is  of  which  the  articular  ligaments  are  fortified  by  ten 
dons,  and  sometimes  completely  replaced  by  ftem  ;  and  I  have  taken  care  to  observe  that  it  is  generally  the 
trochlear  joints  which  exhibit  examples  of  this  replacing  of  ligaments  by  tendons  in  regard  to  extension,  be- 
cause, in  the  movement  of  extension,  a  ligament,  being  a  purely  passive  means  of  union,  was  not  sufficient. 
What  would  take  place  if  an  ordinary  ligament  were  to  be  substituted  for  the  tendon  of  the  extensor  muscles  t 
In  the  first  place,  this  ligament  would  have  to  be  extremely  long  to  permit  flexion  ;  but  in  case  it  should  be 
long  enough  for  flexion,  what  would  become  of  it  in  the  movement  of  extension  ?  Unless  it  were  endowed 
witn  the  extensibility  and  the  elasticity  of  the  yellow  ligaments,  it  would  become  folded,  and  would  thrust 
itself  between  the  articular  surfaces.   It  is  for  this  reason  that  a  ligament  was  required  which  might  be  short 


ARTICULATIONS    OF    THE    KNEE-JOINT.  Ifffe 

joint  there  are  two  interosseous  ligaments  {g  i,fig-  78),  so  arranged  as  to  admit  of  the 
most  extensive  flexion,  but  to  limit  the  movement  of  extension.  They  are  called  cniciaU 
because  they  cross  each  other  like  the  letter  X.  They  are  situated  in  the  deep  inter- 
condyloid  fossa,  whose  sole  destination  appears  to  be  that  of  protecting  them.  The  an- 
terior {g,Jigs.  78  and  81)  arises  from  the  external  condyle,  and  passes  to  the  fore  part  of 
the  spine  of  the  tibia.  The  •posterior  (t,  fig.  78)  arises  from  the  internal  condyle,  and  is 
fixed  to  the  back  part  of  the  spine.  Both  are  continuous,  by  a  distinct  bundle,  with  the 
external  inter-articular  cartilage ;  never  with  the  internal.  The  names  anterior  and 
posterior  have  been  given  these  ligaments,  from  their  inferior  insertion  ;  for  superiorly 
they  arise  on  the  same  level.  Here  follows  a  more  minute  description  of  their  inser- 
tions above  and  below,  and  of  their  direction. 

The  anterior  crucial  ligament  arises,  as  a  little  band  flattened  from  side  to  side,  from 
the  semilunar  depression,  which  is  concave  superiorly,  and  is  situated  on  the  internal  or 
median  surface  of  the  external  condyle  ;  thence  it  extends  from  above  downward,  from 
without  inward,  and  from  behind  forward,  flattens  from  before  backward,  and  is  inserted 
in  front  of  the  spine  of  the  tibia,  upon  which  spine  it  encroaches  a  little  by  means  of  some 
insertions  which  it  takes  between  the  two  articular  projections  constituting  the  spine. 
From  the  external  edge  of  this  ligament  a  few  fibres  are  given  off,  which  extend  into  the 
external  part  of  the  semilunar  cartilage. 

The  posterior  crucial  ligament  arises  from  the  external  or  median  surface  of  the  inter- 
nal condyle  in  a  semilunar  depression,  entirely  similar  to  the  one  which  is  destined  to  the 
anterior  crucial  ligament ;  like  the  latter,  it  presents  a  threefold  obliquity  from  above  down- 
ward, from  before  backward,  and  from  within  outward ;  it  sends  a  considerable  expan- 
sion to  the  external  inter-articular  cartilage,  and  is  inserted  back  of  the  spine  of  the  tibia. 
Thence  it  follows  that  the  crucial  ligaments  present  a  double  crossing :  1.  A  crossing 
in  an  antero-posterior  direction,  and  this  alone  has  been  observed  with  attention  ;  2.  A 
crossing  in  a  transverse  direction  ;  when  the  tibia  is  rotated  from  within  outward,  the 
crossing  of  these  two  ligaments  increases  to  such  an  extent  that  these  two  ligaments, 
strongly  pressed  against  each  other,  limit  the  motion  ;  in  the  movement  of  rotation  from 
without  inward,  on  the  contrary,  as  the  crossing  diminishes,  they  become  relaxed  and 
parallel ;  both  are  stretched  during  extension,  and  relaxed  during  flexion ;  there  is  an 
exception  for  the  most  anterior  fibres  of  the  anterior  crucial  ligament,  which  are  relaxed 
in  the  middle  state  of  extension,  and  stretched  during  flexion  ;  but  when  the  extension 
is  considerable,  the  anterior  crucial  ligament  is  also  stretched  in  its  anterior  fibres,  which, 
being  pressed  by  the  condyles,  describe  a  curve  anteriorly  concave. 

The  synovial  capsule  of  this  joint  is  the  largest  and  the  most  complicated  of  all  that  ex- 
ist in  the  body.  In  tracing  it  from  the  upper  edge  of  the  patella,  we  find,  behind  the  ten- 
don of  the  extensor  muscles,  a  large  cul-de-sac  {s,fig.  81),  sometimes  replaced  by  a  dis- 
tinct synovial  capsule,  interposed  between  that  tendon  and  the  surface  of  the  femur.  In 
many  subjects,  this  bursa  communicates  with  the  synovial  capsule  of  the  knee-joint  by 
a  more  or  less  considerable  opening,  and  in  such  cases  a  circular  constriction  forms  the 
only  trace  of  separation.  On  each  side  of  the  patella  the  synovial  membrane  extends 
beneath  the  two  vasti,  and  is  sometimes  elevated  from  one  and  a  half  to  two  inches 
above  the  articular  surfaces  ;  the  prolongation  under  the  vastus  externus  is  much  more 
considerable  than  that  under  the  vastus  internus.  The  existence  of  these  two  prolonga- 
tions affords  an  explanation  of  the  sweUings  observed  at  the  sides  of  the  knee  in  dropsy 
of  this  joint ;  and  the  greater  extent  of  the  external  prolongation  explains,  also,  the  great- 
er size  of  the  prominence  on  the  outside.  In  the  inter-condyloid  notch  the  synovial  mem- 
brane envelops  the  crucial  ligaments  ;  then  it  is  reflected  upon  the  posterior  ligament, 
the  lateral  ligaments,  the  semilunar  cartilages,  the  articular  surfaces  of  the  tibia,  and, 
lastly,  the  back  of  the  ligamentum  pateUae  ;  it  next  sends  off  a  prolongation,  containing 
a  few  ligamentous  fibres,  and  extending  from  the  lower  border  of  the  patella  to  the  front 
of  the  inter-condyloid  notch.     This  fold  has  been  incorrectly  termed  the  adipose  ligament 

ened  or  elongated  as  might  be  necessary,  a  tendon  being  the  continuation  of  a  muscle,  that  is,  of  an  organ  at 
once  capable  of  extension,  contraction,  and  endowed  with  elasticity.  Besides  this,  a  bone  was  required  that 
might  complete  the  articulation  on  the  outside,  that  might  fill  the  large  space  which,  during  the  movement 
of  flexion,  would  have  remained  empty  between  the  articular  surfaces,  and  might  glide  without  injury  ovor 
osseous  surfaces,  and  facilitate,  at  the  same  time,  standing  upon  the  knees.  This  threefold  object  has  been 
attained  by  the  patella,  a  sesamoid  bone,  which  is  developed  in  the  substance  of  the  tendon  of  the  extensor 
muscle  of  the  leg,  viz.,  of  the  triceps  femoris,  whose  parallelism,  at  its  insertion  into  the  rotula,  is  destroyed 
by  this  bone. 

Independently  of  the  anterior  ligament,  the  knee-joint  exhibits  a  large  aponeurotic  surface,  formed  by  the 
femoral  aponeurosis,  by  an  aponeurotic  expansion  of  the. fascia  lata,  and  by  another  aponeurotic  expansion  fur- 
nished by  the  tendons  of  the  sartorius,  gracilis,  and  semi-tendinosus  muscles  ;  to  this  latter  expansion  is  joined 
a  fibrous  lamina,  given  off  by  the  tendon  of  the  vastus  externus  and  internus,  which  is  attached  to  the  libia. 
This  large  anterior  aponeurotic  surface  exhibits,  on  a  level  with  the  tendon  of  the  triceps,  a  saltier-shaped  in- 
terlacing, which  closely  adheres  to  this  tendon,  and  seems  destined  to  serve  it  as  a  bridle  ;  on  a  level  with  the 
patella  it  exhibits  a  thin  layer,  which  is  sometimes  interrupt- 3,  and,  so  to  say,  lacerated,  in  consequence  of 
the  sub-cutaneous  synovial  capsule  being  present ;  and  on  a  level  with  the  ligamentum  patelte  it  exhibits 
fibres  running  obliquely  from  above  downward  and  from  without  inward. 

Finally,  I  shall  point  out  as  appendages  of  the  anterior  ligament  two  proper  ligaments  of  the  patella,  one  m 
temal,  the  other  external,  extending  from  the  edges  of  the  patella  to  the  posterior  part  of  each  tuberosity 
these  ligaments  are  broad  and  thin,  and  strongly  adliere  to  the  synovial  capsule. 


166  ARTHROLOGY. 

(ligamentum  mucosum,  t,figs.  78  and  81).  After  having  furnished  this  fold,  the  syno- 
vial membrane  lines  the  posterior  surface  of  the  patella,  and  becomes  continuous  with 
the  cul-de-sac  behind  the  extensor  tendon.  Sometimes  the  prolongation,  known  as  the 
adipose  ligament,  does  not  exist ;  at  other  times  there  is  more  than  one.  I  have  seen 
a  fold  of  the  same  nature  extending  from  that  part  of  the  synovial  membrane  which  lines 
the  extensor  tendon  to  the  surface  of  the  femur  above  the  trochlea.  No  other  synovial 
membrane  in  the  body  is  provided  with  so  large  a  number  of  villous  prolongations,  which, 
in  some  subjects,  may  be  said  to  give  it  a  shaggy  appearance  ;  they  are  especially  met 
with  around  the  patella*  and  the  semilunar  cartilages.  To  these  prolongations  Clopton 
Havers  has  given  the  name  of  synovial  fringes.  Some  deep  fibres  of  the  triceps  cruris 
have  been  regarded  as  a  special  tensor  muscle  of  the  synovial  capsule.  (Vide  Trice fs 
Cruris,  Myology.) 

Sub-synovial  Adipose  Tissue. — From  the  abundance  of  this  tissue  in  the  knee-joint,  its 
disposition  requires  some  special  notice.  It  is  chiefly  met  with  behind  the  ligamentum 
patellae  {_e,fig.  81),  where  it  forms  a  very  thick  layer,  filling  up  the  interval  between  the 
patella  and  the  synovial  membrane.  This  adipose  mass,  which  raises  the  ligamentum 
patellae  in  the  extension  of  the  knee,  and  which,  during  flexion,  fills  the  empty  space 
which  the  movement  of  flexion  produces  between  the  condyles  of  the  femur  and  the  tibia, 
is  situated  to  the  outside  of  the  joint,  between  the  ligamentum  patellae  and  the  synovial 
capsule,  which  is  raised  by  the  mtiss.  This  mass,  on  being  examined  on  the  side  which 
is  contiguous  to  the  joint,  exhibits  several  prolongations,  which  are  somewhat  similar  to 
the  fatty  appendages  of  the  epiploon.  These  appendages  are  all  lined  by  a  fold  of  the 
synovial  capsule  ;  one  of  these  appendages,  supported  by  a  fibrous  bundle,  is  attached 
to  the  inter-condyloid  space,  under  the  name  of  ligamentum  mucosum  patellas,  which  hg- 
ament  is  sometimes  multiple,  and  has  no  other  object  except  to  draw  to  it  the  fatty  mat- 
ter between  the  tibia  and  the  femur  during  flexion  of  the  knee,  and  to  keep  that  matter 
in  its  place  during  the  movement  of  extension.  A  large  quantity  of  fatty  matter  is  also 
found  behind  the  tendon  of  the  triceps  above  the  condyles,  where  that  matter  fills  the  in- 
terval between  this  tendon  and  the  corresponding  part  of  the  femur.  Bundles  of  fatty 
matter  are,  lastly,  foimd  all  around  the  condyles,  as  well  as  in  the  inter-condyloid  notch, 
and  around  the  insertions  of  the  crucial  ligaments.  This  fat,  which  may  be  observed 
even  in  individuals  in  a  state  of  marasmus,  except  that,  under  those  circumstances,  it  is 
more  serous  and  infiltrated,  is  nowhere  more  evidently  than  in  the  knee-joint,  destined  to 
fill  the  intervals  produced  between  the  articular  surfaces  by  certain  attitudes. 

Mechanism  of  the  Femoro-tibial  Articulation. 

1 .  With  regard  to  Strength. — The  strength  of  articulations  is  generally  in  direct  pro- 
portion to  the  extent  of  the  articular  surfaces,  and  there  is  no  joint  more  advantageously 
constructed  in  this  respect  than  the  one  we  have  been  examining.  The  reception  of  the 
spine  of  the  tibia  into  the  inter-condyloid  fossa  also  tends  greatly  to  increase  the  strength 
of  the  joint,  although  it  forms  but  an  imperfect  kind  of  dovetailing.  A  third  and  last  con- 
dition conducive  to  strength  is,  the  multiplicity  of  the  ligaments,  and  of  the  tendons,  sup- 
plying, in  some  respects,  the  deficiencies  in  the  fitting. 

2.  With  regard  to  Mobility. — The  knee,  being  a  hinge-joint,  has  two  principal  move- 
ments, in  opposite  directions,  \iz.,  flexion  and  extension;  but,  as  the  mutual  reception  of 
the  surfaces  is  very  imperfect,  it  is  also  capable  of  some  slight  rotatory  motions. 

In  flexion,  the  surfaces  of  the  tibia,  defended  by  their  inter-articular  cartilages,  glide 
backward  upon  the  condyles  of  the  femur ;  and,  from  the  great  extent  of  the  articular 
surfaces  of  the  last  bone  in  that  direction,  the  movement  can  be  carried  so  far  as  to  per- 
mit the  leg  and  thigh  to  touch.  In  this  movement,  the  lateral,  the  posterior,  and  the  cru- 
cial ligaments  are  relaxed,  except  the  anterior  fibres  of  the  crucial  ligament,  which  are 
stretched  ;  the  ligamentum  patellae  is  stretched ;  the  patella  is  firmly  applied  to  the  front 
of  the  joint,  and  can  neither  be  moved  to  the  right  nor  to  the  left,  as  may  be  done  during 
extension.  In  the  position  of  flexion,  the  patella  fills  up,  as  it  were,  the  great  hiatus  then 
existing  at  the  front  of  the  joint  between  the  femur  and  the  tibia.  Luxation  is  impossible 
during  this  movement,  which  is  only  limited  by  the  mutual  contact  of  the  leg  and  the  thigh. 

In  extension,  the  tibia  and  the  inter-articular  cartilages  glide  in  the  opposite  direc- 
tion. The  movement  is  arrested  when  the  leg  is  in  the  same  line  as  the  thigh,  and 
whatever  muscular  feffort  be  then  made,  the  leg  never  will  pass  that  limit,  excepting 
trom  malformation  of  the  parts.  A  greater  amount  of  extension  is  rendered  impossible, 
both  by  the  shape  of  the  articular  surfaces,  and  by  the  stretching  of  all  the  ligaments,  ex- 
cepting that  of  the  patella,  which  is  completely  relaxed,  and  permits  of  a  great  mobility 
of  that  bone  in  all  directions.  One  circumstance  in  the  shape  of  the  articular  surfaces, 
which  appears  to  be  opposed  to  any  extension  beyond  the  straight  line,  is  the  small  extent 
of  the  trochlea  in  front ;  for,  could  such  extension  take  place,  the  glenoid  cavities  of  the 
tibia  would  then  be  applied  to  a  portion  of  the  trochlea,  much  smaller  than  themselves. 
The  crucial  ligaments  are  especially  intended  to  limit  the  movement  of  extension,  as  the 

*  [Two  slight  folds  of  the  membrane  formed  at  the  sides  of  the  patella  have  been  particularly  described 
inder  the  very  inappropriate  name  of  the  alar  ligaments.^ 


PERONEO-TIBIAL    ARTICULATIONS.  J67 

following  experiment  will  at  once  demonstrate.  Divide  all  the  external  ligaments  of 
the  joint ;  the  crucial  ligaments  will  then  alone  remain ;  then  endeavour  to  extend  the 
leg  beyond  the  ordinary  limits  ;  this  wiU  be  found  impossible  until  these  ligaments  are 
divided.  That  both  the  crucial  hgaments  oppose  the  extension  of  the  limb  beyond  a  cer- 
tain limit,  is  proven  by  dividing  these  ligaments  separately.  So  long  as  one  remains,  no 
matter  which,  the  extension  is  limited.  An  analogous  experiment,  in  which  all  the  hga- 
ments of  the  joint  (even  including  the  crucial)  are  divided,  excepting  the  lateral,  proves 
that  these  are  not  only  opposed  to  lateral  movements,  but  also  limit  extension  with  much 
force ;  this  they  are  enabled  to  do  from  being  situated  nearer  to  the  back  than  to  the 
front  of  the  joint.  Complete  luxation  can  only  be  effected  after  laceration  of  all  the  hga- 
ments which  hmit  extension.  An  interesting  remark,  which  has  been  suggested  to  me 
by'M.  Martin,  is,  that  the  crucial  hgaments  are  not  only  destined  to  limit  the  movement 
of  extension,  but  also — and  this  is,  perhaps,  their  principal  object — to  prevent  the  articu- 
lar surfaces  from  leaving  each  other  in  the  anterior  posterior  direction  during  a  forcible 
extension.  Thus,  the  anterior  crucial  ligament  will  prevent,  in  a  movement  of  exten- 
sion, both  the  displacement  of  the  tibia  backward,  and  that  of  the  femur  forward,  and  the 
posterior  crucial  ligament  will  prevent  both  the  displacement  of  the  tibia  forward,  and 
that  of  the  femur  backward.  It  is  also  important  to  remark,  that  while  standing  upon  the 
feet,  the  ham-strings  being  stretched,  these  extensor  muscles  of  the  leg,  which  are  situa- 
ted upon  the  thigh,  the  rectus  femoris,  and  the  vastus  externus  and  intemus,  are  entirely 
inactive,  as  is  prgved  both  by  the  extreme  mobility  of  the  patella  and  the  relaxed  state  of 
these  muscles  in  a  standing  position,  and  by  the  absence  of  all  sensation  of  lassitude  in 
these  muscles  after  the  vertical  position  upon  the  feet  has  been  continued  for  a  long 
time.  The  extension  of  the  knee,  therefore,  takes  place  without  any  co-operation  on 
the  part  of  the  muscles,  simply  through  the  articular  surfaces  being  juxtaposed  in  all 
their  breadth,  and  by  the  tension  of  the  lateral  and  crucial  ligaments,  which  keeps  the 
articular  surfaces  mechanically  upon  each  other.* 

In  all  these  motions  the  patella  is  fixed ;  it  is  the  femoral  trochlea  which  glides  upward 
or  downward  upon  the  posterior  surface  of  that  bone.  This  almost  invariable  position 
of  the  patella  depends  on  the  inextensibility  of  its  ligament.  The  existence  of  the  patella 
has  no  effect  in  limiting  the  movements  of  extension  ;  its  only  uses,  as  far  as  the  joint 
is  concerned,  are  to  protect  it  in  front,  and  to  prevent  painful  pressure  in  the  kneeling 
posture.  Its  other  and  chief  uses  are  connected  with  the  functions  of  the  triceps  ex- 
tensor muscle,  in  the  tendon  of  which  it  is  developed ;  it  removes  the  axis  of  the  muscle 
from  the  parallel  direction  of  the  lever  which  it  is  destined  to  move.  It  is  movable  and 
depressed  during  extension  of  the  leg,  but  during  flexion  it  becomes  prominent  and  fixed,  t 

Rotation. — When  the  leg  is  semi-flexed  upon  the  thigh,  it  can  be  very  slightly  rotated 
mward  and  outward.  These  movements  are  performed,  not  upon  the  external,  but  upon 
the  internal  condyle  as  a  pivot,  so  that  the  external  part  of  the  head  of  the  tibia  glides 
forward  during  rotation  inward,  and  backward  during  rotation  outward.  The  difference 
in  the  part  performed  by  the  two  condyles  in  the  movement  of  rotation  does  not  depend 
upon  any  peculiarity  of  structure  in  the  joint,  but  exclusively  upon  the  arrangement  of 
the  acting  forces,  as  we  shall  see  when  treating  of  the  muscles.  Rotation  inward  is  limited 
by  the  mutual  contact  of  the  crucial  ligaments,  whose  decussation  is  increased  during  this 
movement.  Rotation  outward  is  more  extensive,  because  in  this  movement  the  liga- 
ments are  uncrossed,  and  become  parallel.  We  shall  see  hereafter  that  the  biceps  is  the 
agent  of  rotation  outward,  and  the  popliteus  of  rotation  inward. 

Peeoneo-tibial  Articulations  {figs.  79  and  80). 

Preparation. — 1.  Remove  carefully  the  muscles  of  the  anterior  and  posterior  regions 
of  the  leg,  which  will  expose  the  interosseous  ligament,  and  the  anterior  and  posterior 
ligaments  of  these  joints.  2.  In  order  to  see  the  interior  of  the  articulations,  saw  through 
the  two  bones  in  the  middle,  and  then  separate  them.   3.  To  gain  an  idea  of  the  interosseous 

*  M.  Robert,  one  of  our  most  distinguished  young  surgeons,  has  observed  a  fact  which  sustains  these  ideas, 
■which  had  already  been  demonstrated  by  the  artificial  legs  of  M.  Martin.  An  individual  in  whom  the  patella 
was  fractured,  had  recovered  with  a  distance  of  about  ten  centimeters.  The  movement  of  extension  by  mus- 
cular contraction  was  impossible  ;  but  when  the  limb  was  extended,  it  maintained  itself  in  that  position  with 
the  same  force  as  the  limb  upon  the  healthy  side.  The  patient  had  succeeded,  by  a  sort  of  artifice,  in  exe- 
cuting spontaneously  the  movement  of  extension  ;  he  brought  the  trunk  and  the  pelvis  forcibly  forward  :  the 
femur  followed  the  pelvis,  and  extension  being  once  effected,  this  inferior  limb,  being  very  strong  and  immo- 
vable, assisted  in  the  standing  position  just  as  much  as  the  healthy  limb. 

t  It  is  during  flexion  of  the  leg,  and,  consequently,  when  the  patella  is  most  immovable,  that  this  bone 
may  be  displaced  in  consequence  of  some  external  violence,  and  in  this  case,  the  displacement  always  takes 
place  to  the  outside.  However,  one  should  suppose  that  the  external  condyle  of  the  femur,  being  much  more 
prominent  than  the  internal,  would  be  opposed  to  the  luxation  outward,  and  favour  the  luxation  inward,  "ut 
we  may  remark,  that  the  patella,  when  displaced  inward,  cannot  remain  in  this  position,  in  which  nothing 
maintains  it,  and  from  which  the  oblique  direction  of  the  triceps  tends,  on  the  contrary,  to  bring  it  back  to  its 
natural  place  ;  whereas,  when  the  patella  is  displaced  outward,  the  prominence  of  the  extorual  condyle  op- 
Tjoses  the  reduction  of  the  patella,  which  can  only  be  effected  by  artificial  means.  It  should  be  remarked,  that 
ttie  obliquity  downward  and  inward  of  the  femoral  trochlea  gives  a  tendency  to  the  patella  of  being  continuaUj 
drawn  outward  by  the  tendon  of  the  extensor  muscles,  which  is  slightly  oblique  in  the  same  direction  as  the 
trochlea.  This  is  so  true,  that  in  white  swellings  of  the  knee-joiut,  the  spontaneous  displacement  of  the  pa- 
tella always  takes  place  outward. 


168  ARTHROLOGY. 

ligament  of  the  inferior  articulation,  saw  perpendicularly  through  the  lower  endc  of  thp 
bones  of  the  leg,  so  as  to  divide  them  into  an  anterior  and  a  posterior  portion. 

The  tibia  and  the  fibula,  which  are  contiguous  at  their  extremities,  are  separated  iVoir 
each  other  along  their  shafts,  the  interval  being  occupied  by  an  aponeurosis,  improperly 
called  the  interosseous  ligament.  We  have,  then,  a  superior  and  an  inferior  peroneo-tibiai 
articulation,  and  an  interosseous  ligament  or  aponeurosis. 

1.  Superior  Peroneo-tibial  Articulation. 

Tliis  articulation  is  an  arthrodia.  The  articular  facette  of  the  tibia,  looking  downward 
and  outward,  is  situated  behind  its  external  tuberosity.  I'he  facette  of  the  fibula  looks 
upward  and  inward  ;  it  occupies  the  inner  part  of  the  upper  end  of  the  bone.  The  means 
of  union  are  two  ligaments  :  an  anterior  {g,  Jig.  80)  and  p.  posterior  {d,  Jig.  79).  They 
are  composed  of  parallel  fibres,  directed  obliquely  downward  and  outward  from  the  exter- 
nal condyle  of  the  tibia  to  the  heaji  of  the  fibula.  There  is  generally  a  distinct  synovial 
membrane  for  this  joint,  but  sometimes  it  is  a  prolongation  from  the  capsule  of  the  knee. 
This  communication  frequently  existing  between  the  synovial  capsule  of  the  knee  and 
the  peroneo-tibial  articulation,  should  condemn,  in  an  amputation  of  the  leg,  the  practice 
of  extirpating  the  superior  extremity  of  the  fibula.  The  formidable  accidents  which 
might  be  consequent  upon  such  an  extirpation  may  readily  be  conceived,  and  should  for- 
bid the  operation,  although  it  has  been  accomplished  without  any  accident.  Its  only  ob- 
ject is  to  prevent  the  fibula  from  pressing  upon  the  soft  parts. 

2.  Inferior  Peroneo-tibial  Articulation. 

This  articulation  is  an  amphi-arthrosis,  that  is,  it  is  formed  between  surfaces  that  are 
partly  contiguous  and  partly  continuous.  The  former  consists  of  two  articular  facettes, 
narrow  from  above  downward,  and  oblong  from  before  backward  ;  of  these,  one  is  con- 
vex, and  situated  upon  the  internal  surface  of  the  lower  end  of  the  fibula  above  the  mal- 
leolus ;  the  other  is  concave,  and  continuous  with  the  inferior  or  tarsal  articular  surface 
of  the  tibia.  They  are  both  covered  with  cartilage.  The  continuous  surfaces  are  rough, 
and  much  more  extensive  ;  they  are  triangular  in  shape,  having  their  bases  directed  down- 
ward :  the  one  situated  upon  the  fibula  is  convex,  that  upon  the  tibia  is  slightly  concave. 

The  means  of  union  are,  two  ligaments  external  to  the  joint,  and  an  interosseous  liga- 
ment connecting  the  two  triangular  surfaces  just  mentioned.  Of  the  two  external  liga- 
ments, one  is  anterior  (i.  Jig.  80)  and  the  other  posterior  {e,  Jig.  79).  They  are  both  very 
strong,  and  composed  of  thick,  shining,  parallel  fibres,  which  pass  obliquely  downward 
and  outward  from  the  tibia  to  the  fibula.  They  are  almost  always  divided  into  two  dis- 
tinct bundles.  They  are  both  remarkable  from  descending  beyond  the  articular  surfa- 
ces, so  that  they  increase  the  depth  of  the  cavity  for  the  reception  of  the  astragalus. 
The  sijnovial  membrane  of  this  articulation  is  a  prolongation  from  that  of  the  ankle-joint 
The  interosseous  ligament  consists  of  fibrous  bundles,  mixed  with  adipose  tissue,  which 
unite  the  two  triangular  surfaces  so  firmly  that  the  fibula  is  sometimes  fractured  in  at- 
tempting to  rupture  the  ligaments. 

3.  Interosseous  Aponeurosis. 
The  name  of  interosseous  ligament  is  given  to  an  aponeurotic  septum  {b,figs.  79  and 
80)  placed  between  the  muscles  of  the  anterior  and  those  of  the  posterior  aspect  of  the 
leg ;  it  should  rather  be  regarded  as  serving  to  multiply  the  points  of  insertion  for  fibres 
of  those  muscles,  than  as  a  means  of  union  between  the  bones  of  the  leg.  It  is  narrow- 
er below  than  above,  and  is  composed  of  fibres  running  obliquely  downward  and  outward 
from  the  outer  edge  of  the  tibia  to  the  longitudinal  crest  on  the  inner  surface  of  the 
fibula.  As  in  the  interosseous  ligament  of  the  forearm,  we  find  some  other  fibres  cross- 
ing the  former  at  an  acute  angle.  The  septum  thus  formed  is  interrupted  above  and  be- 
low for  the  passage  of  the  tibial  vessels  ;  the  peroneal  artery  and  veins  traverse  the  low- 
er opening  ;  the  anterior  tibial  artery  and  veins  pass  through  the  upper. 

Mechanism  of  the  Peroneo-tibial  Articulations. 
The  fibula  is  only  capable  of  almost  imperceptible  gliding  movements  upon  the  tibia. 
This  arrangement  is  directly  connected  with  the  mechanism  of  the  ankle-joint. 

Ankle,  or  Tibio-taksal  Joint  (Jigs.  79  and  80).* 
Preparation. — Cut  and  turn  back  the  tendons  that  are  reflected  round  the  joint,  and 
remove  tl\e  sheaths  of  those  tendons  by  which  most  of  the  ligaments  are  covered.  The 
peroneo-calcanean  ligament  is  seen  after  the  tendons  of  the  peroneal  muscles  have  been 
removed ;  the  synovial  membrane  of  these  tendons  only  covers  it.  The  peroneo-astra- 
galian  ligament  is  the  most  difficult  to  uncover,  on  account  of  its  being  deeply  seated, 
and  separated  from  the  sheath  of  the  muscles  of  the  posterior  region  by  a  large  quantity 
of  adipose  tissue.  The  internal  lateral  ligament  is  seen  immediately  beneath  the  sheaths 
of  the  tibialis  posticus,  the  common  flexor  tendon  of  the  toes,  and  the  proper  flexor  of  the 

*  We  should  remark  th&t,  in  order  to  study  this  as  well  as  all  the  other  articulations  efficiently,  it  is  a  great 
ijvantage  to  be  provided  with  two  joints,  of  which  one  is  opened,  while  the  other  has  its  ligaments  untouched 


ARTICULATIONS    OF    THE    ANKLE-JOINT.  169 

great  toe.  In  order  to  see  the  deep  layer  of  this  ligament,  the  superficial  laj  ers  must 
be  removed  one  after  the  other. 

The  tibio-tarsal  articulation  belongs  to  the  class  of  angular  ginglymt. 

Articular  Surfaces. — Both  bones  of  the  leg  participate  in  this  joint,  their  1  >wer  extrem- 
ities being  united  to  form  a  transversely  oblong  socket,  of  which  the  tibia  constitutes  by 
far  the  greater  part.  On  this  articular  surface  there  is  an  antero-posterior  ridge,  corre- 
sponding to  the  groove  of  the  trochlea  on  the  astragalus,  and  separating  two  shallow  cav- 
ities. The  socket  is  bounded  by  the  malleoli  on  each  side.  The  internal  or  tibial  mal- 
leolus corresponds  to  the  internal  lateral  articular  surface  of  the  astragalus  ;  and  the  ex- 
ternal or  fibular  malleolus,  to  the  external  lateral  facette  of  the  same  bone.  The  tibio- 
peroneal  cavity  is  completed  forward  and  backward  by  the  lower  part  of  the  anterior  and 
posterior  peroneo-tibial  ligaments.  The  superior  articular  surface  of  the  astragalus  is 
a  trochlea  ;  it  is  oblong  from  before  backward,  thus  contrasting  with  the  cavity  on  the 
lower  extremity  of  the  leg,*  which  is  transversely  oblong.  This  trochlea  presents  a 
shallow  depression,  running  from  before  backward,  and  having  an  external  and  an  internal 
edge,  the  external  being  the  more  elevated  of  the  two.  The  pulley  of  the  astragalus  is 
continuous  with  its  lateral  articular  surfaces,  of  which  the  external  is  by  far  the  larger. 

The  means  of  union  are  three  external  lateral  ligaments,  two  internal  lateral  ligaments, 
an  anterior  {r,Jig.  80)  and  a  posterior  {s,fig.  79)  ligament,  and  a  synovial  capsule. 

The  external  lateral  or.  peroneo-tarsal  ligaments  are  three  in  number;  they  all  proceed 
from  the  fibula,  either  to  the  astragalus  or  the  os  calcis. 

1.  The  external  lateral  ligament,  properly  so  called  (ligamentum  fibulae  medium  vel  per- 
pendiculare,  m,.figs.  79  and  80),  is  situated  beneath  the  sheath  of  the  peroneus  longus 
and  brevis.  It  arises  from  the  summit  of  the  external  malleolus,  is  directed  downward 
and  shghtly  backward,  to  be  attached  to  the  outside  of  the  os  calcis.  It  is  rounded,  and 
composed  of  parallel  fibres. 

2.  The  anterior  external  lateral  ligament  (ligamentum  fibulae  anterius,  n,  fig.  80)  arises 
from  the  anterior  edge  of  the  externed  malleolus,  and  proceeding  downward  and  forward, 
is  fixed  to  the  astragalus  in  front  of  its  external  malleolar  facette.  It  is  very  short,  and 
broader  below  than  above :  it  forms  one  of  the  two  anterior  hgaments  described  by  Bi- 
chat  in  this  joint. 

3.  The  posterior  lateral  ligament  (ligamentum  fibulae  posterius,  o,fig.  79)  is  very  deeply 
seated  behind ;  it  extends  from  the  excavation  on  the  inside  and  behind  the  external 
malleolus  to  the  posterior  border  of  the  astragalus,  immediately  above  the  pulley  of  this 
bone.  It  is  directed  almost  horizontally,  or  in  a  slight  degree  obliquely  downward  and 
inward,  and  is  almost  parallel  to  the  posterior  ligament  of  the  lower  peroneo-tibial  ar- 
ticulation. It  is  composed  of  very  distinct  parallel  fibres,  which  are  arranged  in  several 
layers,  the  deepest  of  which  are  attached  to  the  astragalus  behind  the  facette  of  the  ex- 
ternal malleolus.  The  posterior  peroneo-astraglagean  ligament  is  very  strong.  Bichat 
calls  it  the  posterior  ligament  of  the  joint. 

The  interTwl  lateral  ligament  is  much  stronger  than  the  three  external  ligaments  taken 
together.  It  is  composed  of  two  very  distinct  layers  :  1.  A  superficial  layer,  consistiiig  of 
fibres  stretched  from  the  apex  and  the  anterior  and  posterior  borders  of  the  internal  mal- 
leolus to  the  OS  calcis,  and  the  upper  edge  of  the  lower  calcaneo-scaphoid  ligament,  which 
it  maintains  in  a  state  of  constant  tension.  The  fibres  are  long  and  slightly  divergent, 
but  still  sufficiently  so  to  have  given  origin  to  its  name  of  the  deltoid  ligament  {p,figs.  79 
and  80).  The  fibres  which  are  most  anterior  pass  directly  forward  to  the  neck  of  the 
astragalus,  and  to  the  scaphoid  ;  they  form  a  very  thin  layer,  which  has  been  improper- 
ly called  the  anterior  ligament  of  the  ankle-joint.  2.  Below  the  above  is  a  deep  layer  of 
much  greater  extent,  composed  of  sliort  and  strong  bundles,  passing  downward  and  out- 
ward from  the  sununit  and  sides  of  the  internal  malleolus,  to  the  inner  surface  of  the  as- 
tragalus, below  the  articular  facette.  + 

Synovial  Capsule. — The  external  surface  of  this  membrane  is  brought  into  view  in 
front  and  behind  by  removing  the  tendons  and  their  sheaths  ;  and  if  the  external  and  in- 
ternal lateral  ligaments  be  divided,  it  will  be  seen  to  extend  into  the  inferior  peroneo- 
tibial articulation.  It  will  also  be  observed  that  it  is  tense  at  the  sides,  but  very  loose 
behind,  and  more  particularly  so  in  front.  A  great  quantity  of  adipose  tissue  covers  its 
external  surface  in  these  situations. 

Mechanism  of  the  Ankle-joint. 
This  articulation  not  only  constitutes  the  point  at  which  the  weight  of  the  body  is 

*  Hence,  the  longest  diameter  of  the  astraglagean  cavity  is  from  before  backwaril ;  the  longest  diametei 
of  the  tibio-peroneal  cavity  is  transversely.  The  extent  of  the  movements  of  flexion  and  extension  ol  '"« '9°' 
depends  upon  the  disproportion  between  the  antero-posterior  diameter  of  the  pulley  of  the  astragalus  ana  me 
socket  of  the  leg.  ,  „„„._„„, 

t  [The  author  has  omitted,  perhaps  intentionally,  to  give  a  special  description  of  the  anterior  anu  posienor 
ligaments  of  the  ankle-joint,  already  alluded  to  by  him.  The  former  extends  from  the  anterior  margin  oi  tne 
articular  surface  of  the  tibia  to  the  corresponding  border  of  the  astragalus,  a  id  is  called  the  wno-iarsai  itg- 
ament ;  it  is  very  thin,  and  covered  by  the  tendons  of  the  extensor  muscles.  The  posterior  can  scarcely  De 
said  to  exist  as  a  distinct  ligament.] 


15» 


ARTHROLOGY. 


transmitted  to  the  foot,  but  also  performs  a  very  active  part  in  the  movements  of  pro- 
gression ;  it  is  therefore  so  constructed  as  to  unite  great  strength  with  the  capability  of 
tolerably  extensive  motion. 

With  regard  to  strength,  the  following  arrangements  should  be  noticed  as  especially  ad- 
vantageous :  1.  The  leg  being  articulated  with  the  foot  at  a  right  angle,  transmits  the 
weight  of  the  body  directly  to  it,  and  this  transmission  being  effected  in  the  perpendicular 
direction,  i.  c,  in  a  direction  in  which  the  articular  surfaces  mutually  oppose  each  other, 
has  no  tendency  either  to  produce  fatigue  or  to  rupture  the  ligaments.  The  perpendic- 
ular position  of  the  leg  upon  the  foot  during  standing  is  worthy  of  notice,  because  of  it- 
self it  proves  that  man  was  intended  for  the  erect  posture,  since  in  this  attitude  alone 
does  the  entire  inferior  surface  of  the  foot  rest  upon  the  ground.  It  should  be  also  re- 
marked, that  there  is  no  other  articulation,  excepting  that  of  the  head  upon  the  verte- 
bral column,  in  which  the  parts  united  are  habitually  perpendicular  to  each  other.  2. 
The  dovetailing  effected  at  this  joint,  by  the  reception  of  the  astragalus  into  the  socket, 
formed  by  the  bones  of  the  leg,  is  also  highly  conducive  to  its  strength.  This  dovetail- 
ing results  both  from  the  pulley-like  surface  of  the  astragalus,  and  from  the  angular  form 
of  the  tibio-fibular  socket ;  and  it  should  be  observed,  that  this  latter  condition  is,  as  it 
were,  peculiar  to  the  ankle-joint,  for  in  no  other  do  we  meet  with  such  abrupt  angles. 

With  regard  to  mobility,  the  tibio-tarsal  articulation  admits  of  flexion  and  extension. 
There  is  no  lateral  motion,  the  movements  of  the  foot  in  this  direction  being  almost  ex- 
clusively performed  at  the  tarsal  joints. 

Inflexion,  the  astragalus  gUdes  backward  upon  the  tibia  and  fibula,  and  the  back  part 
of  the  pulley  projects  behind.  Luxation,  from  an  excess  of  this  movement,  is  almost 
impossible,  for  it  is  limited  by  the  meeting  of  the  neck  of  the  astragalus  and  the  anterior 
edge  of  the  tibio-fibular  sockets.  In  this  movement,  the  posterior  extern2d  lateral  liga- 
ment, and  the  middle  and  posterior  fibres  of  the  internal  lateral  ligament,  are  put  upon 
the  stretch. 

In  extension,  on  the  contrary,  the  trochlea  of  the  astragalus  glides  forward  upon  the 
corresponding  surface  ;  the  synovial  membrane  is  borne  upward  in  front ;  the  anterior 
external  lateral  ligament,  and  the  anterior  and  middle  fibres  of  the  internal  lateral  liga- 
ment, are  stretched.     Luxation  is  possible  during  this  motion,  but  is  very  rare. 

Lateral  Movements. — Although  the  shape  of  the  joint  is  opposed  to  movements  of  this 
kind,  yet  it  cannot  be  doubted  that  the  elasticity  of  the  fibula,  by  allowing  the  external 
malleolus  to  yield  a  little,  may  permit  them  in  a  slight  degree.  Nevertheless,  the  fibula 
must  be  fractured,  if  any  force,  exerted  by  the  astragalus  against  the  external  malleolus, 
be  carried  so  far  as  to  thrust  it  much  outward. 

Articulations  of  the  Tarsus  {figs.  80,  82,  83,  84). 

The  intrinsic  articulations  of  the  tarsus  comprise,  L  The  articulations  of  the  compo-- 
nent  bones  of  each  row.     2.  The  articulation  of  the  tv/o  rows  together. 

Preparation. — 1.  Remove  the  tendons  situated  upon  the  dor- 
sum of  the  foot,  and  also  the  extensor  brevis  digitorum  mus- 
cle. 2.  Remove  all  the  muscles  of  the  plantar  region.  3.  Rub 
off,  by  means  of  a  rough  cloth,  the  adipose  tissue  covering  the 
ligaments  (a  subject  much  infiltrated  with  serum  is  best  adapted 
for  this  purpose).  4.  In  order  to  gain  a  clear  comprehension  of 
the  articulation  of  the  two  rows  together,  remove  the  astrag- 
alus from  the  sort  of  box  in  which  it  is  contained,  by  divi- 
ding the  interosseous  ligament  which  unites  it  to  the  os  calcis. 
5.  For  the  examination  of  the  interosseous  ligaments,  it  is  ne- 
cessary to  separate  the  bones  by  laceration  or  section  of  those 
ligaments  ;  the  resistance  experienced  in  doing  this,  and  the 
portions  of  the  ligaments  remaining  attached  to  the  bones,  will 
give  a  good  idea  of  their  strength  and  situation.  6.  In  order 
to  obtain  a  correct  notion  of  all  the  ligaments  together,  it  is 
necessary,  while  studying  each,  at  the  same  time  to  examine 
a  foot  in  which  all  the  joints  have  been  opened  above,  while 
the  bones  are  still  retained  in  their  situations  by  means  of  the 
plantar  ligaments. 

Articulation  of  the  Component  Bones  of  the  First  Row,  or  Articula- 
tion of  the  Astragalus  with  the  Os  Calcis. 

This  is  a  double  arthrodia,  in  which  each  of  the  bones  pre- 
sents two  articular  facettes,  separated  by  a  furrow  deeper  on 
the  outer  than  on  the  inner  side.  Tlie  posterior  surface  of  the 
astragalus  (1,  fig.  84)  is  concave,  that  of  tlie  os  calcis  (2)  is 
convex ;  in  front  (1)  the  opposite  obtains,  so  that  there  is  a  mu- 
tual reception  of  parts.  The  means  of  union,  properly  speak 
ing,  consist  only  of  an  extremely  strong  interosseous  ligament  (a, 


Fig.SZ. 


ARTICULATIONS   OF   THE   TARSUS. 


171 


/Jg'.  84)  formed  by  ligamentous  bundles,  of  which  some  are  vertical,  and  others  oblique  , 
they  are  mixed  with  fat,  and  occupy  the  considerable  interval  formed  by  the  grooves  of 
the  two  bones,  and  which  is  larger  towards  the  outer  end.  To  form  a  complete  idea  of 
this  ligament,  it  is  necessary  to  make  a  vertical  section  from  before  backward,  through 
the  middle  of  the  astragalus  and  os  calcis  (as  in^^.  84).  A  loose  synovial  membrane 
lines  the  posterior  articulation,  which  is  strengthened  on  the  inside  by  the  fibrous  sheaths 
of  the  tendons  of  the  tibialis  posticus,  the  flexor  longus  digitorum,  and  the  flexor  longus 
poUicis.  There  are  also  about  this  joint  two  very  small  fibrous  bundles,  one  of  which 
is  posterior  {t,  fig.  80  ;  a,  fig.  83),  and  the  other  external  {Jb,  fig.  83) :  some  anatomists 
have  described  them  by  the  names  of  posterior  and  external  ligaments.  The  anterior  por- 
tion of  this  articulation  is  often  double,  from  the  division  of  the  anterior  articular  sur- 
faces into  two  smaller  facettes  :  it  forms  part  of  the  astragalo-scaphoid  articulation,  with 
which  it  will  be  described. 

Articulations  of  the  Component  Bones  of  the  Second  Row. 

All  these  joints  are  very  compact,  for  the  five  bones  which  constitute  this  row  act  as 
one  only  in  the  movements  perfonned  by  the  foot  at  its  tarsal  pig,  93. 

articulations.  They  present  for  the  most  part  angular  facettes  ; 
they  have  also  interosseous  ligaments,  and  are  true  symphyses 
or  amphiarthroses. 

Articulations  of  the  Cuneiform  Bones  with  each  other. 

Articular  Surfaces. — The  corresponding  surfaces  of  the  first 
and  second  cuneiform  bones  present  contiguous  as  well  as  con- 
tinuous portions.  The  contiguous  portions  are  square,  and  sit- 
uated at  the  upper  and  back  part  of  each  surface.  The  con- 
tinuous portions  are  placed  in  front  of  the  preceding.  The 
corresponding  articular  surfaces  of  the  second  and  third  cunei- 
form bones  are  smooth  and  contiguous  behind,  but  rough  and 
irregular  in  front. 

Means  of  Union. — 1.  By  dorsal  ligaments  {c  c,  fig.  83).  This 
name  is  given  to  some  very  compact  fibrous  bands  stretching 
transversely  from  one  bone  to  the  other.  By  their  upper  sur- 
faces, on  which  the  longest  fibres  may  be  seen,  they  are  in  re- 
lation with  the  extensor  brevis  digitorum  and  with  the  tendons 
of  the  other  extensor  muscles.  Their  lower  surfaces,  the 
fibres  of  which  are  shorter,  correspond  to  the  articulations,  and 
to  the  periosteum  of  the  cuneiform  bones,  with  which  they  in- 
terlace. 2.  By  plantar  ligaments.  This  name  may  be  given 
to  some  of  the  fibres  of  the  interosseous  ligaments.  3.  By  in- 
terosseous ligaments.  These,  which  are  very  strong,  consti- 
tute the  principal  means  of  union  of  these  joints,  and  occupy 
all  the  rough  portions  of  the  corresponding  facettes.  They 
so  closely  unite  the  bones,  that,  even  when  the  dorsal  liga- 
ments are  removed,  it  is  not  easy  to  open  the  joints. 

The  synovial  membrane  is  merely  a  portion  of  the  general  sjrnovial  membrane  of  the 
tarsus. 

Articulations  of  the  Scaphoid  vnth  the  Cuneiform  Bones. 

Articular  Surfaces. — The  scaphoid  presents  the  only  example  in  the  body  of  a  single 
articular  surface  being  divided  into  three  facettes  by  well-marked  ridges.  Each  of  these 
facettes  is  triangular,  and  corresponds  to  a  surface  of  the  same  form  on  one  of  the  cunei- 
form bones.  The  base  of  the  triangular  facette  for  the  first  cuneiform  bone  is  below ; 
the  bases  of  the  other  two  are  above  (3,  fig.  80). 

Means  of  Union. — 1 .  Dorsal  ligaments.  There  are  two  for  the  first  cuneiform  bone,  a 
superior  (d,  fig.  83),  and  an  internal  (c,  figs.  83  and  84) ;  and  only  one  for  each  of  the  oth- 
ers (//,  fig.  83).  The  dorsal  ligaments  of  the  first  cuneiform  bone  pass  directly  back- 
ward ;  those  of  the  other  two  are  stretched  obliquely  for^vard  and  outward.  2.  Plantar 
ligaments.  A  very  strong  plantar  ligament  (a,  fig.  82)  extends  from  the  tubercle  of  the 
scaphoid  to  the  corresponding  tubercle  of  the  first  cuneiform  bone  ;  it  is  blended  with  the 
tendon  of  the  tibialis  posticus,  which  furnishes  a  considerable  expansion  that  crosses  the 
direction  of  the  tendon  of  the  peroneus  longus,  and  extends  to  the  third  cuneiform,  and 
the  corresponding  metatarsal  bone  ;  it  may  be  considered  as  an  inferior  ligament  of  the 
tarsus.  The  name  of  plantar  ligaments  can  scarcely  be  given  to  some  irregular  fibres 
{h,fig.  82)  passing  from  the  lower  surface  of  the  scaphoid  to  the  second  and  third  cunei- 
form bones. 

A  synovial  membrane,  common  to  the  three  articulations,  is  continuous  with  that  of  the 
three  cuneiform  bones. 


)J|S  ARTHROLOGY. 

Articulation  of  the  Third  Cuneiform  Bone  with  the  Cuboid. 
This  articulation  resembles  in  every  respect  those  of  the  cuneiform  bones.  The  means 
of  union  are  a  dorsal  ligament  {g,  fig.  83),  consisting  of  a  very  strong  transverse  bundle  ; 
an  interosseous  ligament,  which  occupies  the  entire  non-articular  portion  of  the  correspond- 
ing surfaces  ;  and  an  ill-defined  plantar  ligament,  consisting  of  some  irregular  transverse 
fibres.  The  synovial  membrane  communicates  with  that  of  the  cuneo-scaphoid  articulations. 

Articulation  of  the  Scaphoid  with  the  Cuboid. 

The  scaphoid  and  the  cuboid  often  unite  by  a  small  facette.  The  means  of  union  are 
an  oblique  dorsal  ligament  {i,  fig.  83),  a  very  strong  interosseous  ligament,  occupying  the 
whole  of  the  corresponding  surfaces  of  the  bones,  excepting  the  small  portions  which 
are  contiguous  ;  and  a  very  thick  transverse  plantar  ligament,  extending  somewhat  ob- 
liquely from  the  tuberosity  of  the  scaphoid  to  the  cuboid.  These  ligaments  exist  even 
when  there  are  no  articular  facettes. 

Articulation  between  the  two  Rows  of  the  Tarsal  Bones. 
The  articulation  between  the  two  rows  consists  of  the  articulation  of  the  astragalus 
with  the  scaphoid  and  os  calcis,  the  articulation  of  the  os  calcis  with  the  cuboid,  and, 
lastly,  the  union  of  the  os  calcis  to  the  scaphoid  by  means  of  several  ligaments. 

1 .  Articulation  of  the  Astragalus  with  the  Scaphoid. 

The  articular  surface  on  the  head  of  the  astragalus  {.I,  fig.  84),  elongated  from  without 
jPt^.  84.  inward,  and  from  above  down- 

ward, is  larger  than  the  glenoid 
cavity  of  the  scaphoid  (3),  and  pro- 
jects considerably  below  it,  where 
it  articulates  with  the  anterior  fa- 
cette, or  the  two  anterior  semi- 
facettes  of  the  os  calcis.  The 
cavity  of  reception  is  completed 
by  a  ligament  called  the  inferior 
calcaneo-scaphoid  {b),  which  occu- 
pies the  triangular  interval  be- 
tween the  small  tuberosity  of  the 
os  calcis  and  the  scaphoid,  and 
y  forms  by  itself  the  inner  side  of 

the  cavity  of  reception.  In  order  to  obtain  a  good  view  of  this  ligament,  it  is  advisable 
to  remove  the  astragalus  by  cutting  and  tearing  the  interosseous  ligament  that  unites  it 
to  the  OS  calcis  ;  it  will  then  be  seen  that  the  ligament  we  are  describing  is  very  strong 
and  triangular,  and  that  it  covers  not  only  the  lower,  but  the  inner  part  also  of  the  head 
of  the  astragalus.  It  is  often  divided  into  two  parts  :  one  being  external,  narrow,  and 
shaped  like  a  band ;  the  other  internal,  much  broader  and  thicker,  in  relation  below  with 
the  sesamoid  bone  of  the  tendon  of  the  tibialis  posticus,  and  presenting  a  cartilaginous 
thickening  at  the  corresponding  point. 

Another  ligament,  called  the  superior  calcaneo-scaphoid  {I,  fig.  83),  must  also  be  regard 
ed  as  contributing  to  wedge  in  the  astragalus  ;  it  extends  from  the  inside  of  the  anterior 
extremity  of  the  os  calcis  to  the  outside  of  the  scaphoid.  It  is  situated  upon  the  dorsum 
of  the  foot,  in  the  deep  hollow  occupied  by  fat,  on  the  outer  side  of  the  astragalus. 
These  two  ligaments  (the  inferior  and  superior  calcaneo-scaphoid)  constitute  the  means 
of  union  between  the  os  calcis  and  the  scaphoid.  These  bones  are  in  no  part  contigu- 
ous ;  but  occasionally  we  find  the  os  calcis  continued  into  the  scaphoid,  through  the  me 
dium  of  an  osseous  lamina,  which  replaces  the  lower  calcaneo-scaphoid  ligament.* 

The  OS  calcis  being  very  securely  articulated  with  the  astragalus,  and  at  the  same 
time  very  firmly  connected  with  the  scaphoid,  it  follows  that  the  articulation  between  the 
scaphoid  and  astragalus  possesses  great  strength,  although  the  ligaments  directly  uniting 
them  are  by  no  means  powerful ;  just  as  the  atlas,  which  is  but  slightly  connected  with 
the  occipital  bone  by  means  of  its  own  ligaments,  is  very  firmly  fixed  by  the  ligaments 
stretching  from  the  occipital  bone  to  the  axis.  Nevertheless,  the  absence  of  any  very 
strong  and  direct  means  of  union  between  these  bones  renders  it  possible  for  the  astrag- 
alus to  be  forced  by  externeil  violence  out  of  the  sort  of  osseo-fibrous  socket  in  which 
it  is  placed. 

The  superior  astragalo-scaphoid  ligament  {s,fig.  80 ;  m,figs.  83  and  84)  is  the  only  one 
proper  to  this  joint ;  it  is  semicircular  in  form,  and  extends  somewhat  obliquely  forward 
and  outward,  from  the  neck  of  the  astragalus  to  the  margin  of  the  facette  on  the  sca- 
phoid. It  is  thin  in  texture,  and  consists  of  parallel  fibres ;  it  is  covered  by  the  ex 
tensor  brevis  digitorum  above,  and  is  lined  below  by  the  synovial  membrane  of  the  articu- 
lation between  the  scaphoid  and  the  astragalus. 

*  I  have  represented  a  case  of  this  nature  (vide  Anat.  Pathol,  avec  Planches,  liv.  ii.,  pi.   v.). 


ARTICULATIONS    OF    THE    TARSUS.  l73 

2.   Calcaneo-cuhoid  Arliculahon. 

This  articulation  is  upon  the  same  line  as  the  astragalo-scaphoid  ;  an  anatomical  fact 
which  has  suggested  the  ingenious  idea  of  a  partial  amputation  of  the  foot  between  the 
two  rows.  It  belongs  to  the  class  we  have  designated  articulations  by  mutual  reception, 
and  of  which  we  have  found  examples  in  the  sterno-clavicular  joint,  and  the  carpo-meta- 
carpal  articulation  of  the  thumb. 

Articular  Surfaces  (2,  fig.  80). — The  facette  of  the  os  calcis  is  concave  from  above 
downward,  while  the  surface  of  the  cuboid  is  concave  transversely,  that  is,  in  a  direc- 
tion at  right  angles  to  that  of  the  former.  At  the  lower  part  of  the  facette  of  the  os  cal- 
cis there  is  a  horizontal  projection,  which  sometimes  stops  the  knife  during  the  disartic- 
ulation of  the  two  rows. 

The  means  of  union  consist  of  three  ligaments  :  an  inferior  or  plantar,  an  internal,  and 
a  superior.  The  inferior  -plantar,  or  calcatieo-cuboid  ligament  (ligamentum  longum  plantae, 
c  d,figs.  82  and  84),  is  the  strongest  of  all  the  tarsal  ligaments,  forming  a  broad  band  of 
pearly- white  fibres,  directed  from  before  backward.  These  fibres  constitute  a  very  thick 
bundle,  and  extend  from  all  the  under  surface  of  the  os  calcis,  excepting  the  posterior 
tuberosities,  to  the  posterior  margin  of  the  groove  of  the  cuboid.  If  the  fibres  of  this 
ligament  be  removed  layer  by  layer,  we  soon  arrive  at  a  more  deeply-seated  ligament, 
separated  from  the  first  by  some  fatty  tissue  :  it  extends  obliquely  inward,  from  a  tuber- 
osity at  the  forepart  of  the  under  surface  of  the  os  calcis,  to  all  that  portion  of  the  infe- 
rior surface  of  the  cuboid,  situated  behind  its  groove.  There  are,  therefore,  two  inferior 
calcaneo-cuboid  ligaments  :  a  deep  (c)  and  a  superficial  {d). 

The  internal  calcaneo-cuhoid  ligament  {n,  fig.  83)  is  short,  narrow,  quadrilateral,  and 
very  strong  ;  it  is  placed  at  the  side  of  the  superior  calcaneo-scaphoid  ligament,  in  the 
deep  excavation  between  the  astragalus  and  the  os  calcis.  These  two  ligaments  are 
separated  in  front,  but  blended  together  behind,  so  as  to  resemble  the  letter  Y.  They 
may  be  considered  as  in  some  measure  forming  the  key  of  the  articulation  of  the  two 
rows  of  tarsal  bones  ;  for,  during  disarticulation,  the  articular  surfaces  are  easily  separ- 
ated as  soon  as  they  are  divided. 

The  superior  calcaneo-cuboid  ligament  (o,  fig  83)  is  only  a  very  thin,  small  band  of  fibres, 
extending  directly  forward,  from  the  os  calcis  to  the  cuboid. 

Mechanism  of  the  Tarsal  Articulations. 

We  should  examine  the  mechanism  of  the  tarsal  articulations  both  as  regards  their 
strength  and  their  mobility. 

With  regard  to  Strength.  —  The  tarsus  forms  the  fiindamental  part  of  the  foot ;  one 
might,  in  fact,  consider  the  metatarsus  and  the  toes  as  superadded  structures,  for,  even 
when  they  are  removed,  the  foot  fulfils  its  office  as  a  basis  of  support  very  efficiently. 
Surgeons  avail  themselves  of  this  fact  in  performing  partial  amputations  of  the  foot  at 
the  tarsal  and  tarso-metatarsal  articulations. 

The  construction  of  the  tarsus  is,  in  every  respect,  adapted  to  ensure  strength ;  the 
number  of  its  pieces,  the  breadth  of  the  articular  surfaces,  the  strength  of  the  interosse- 
ous ligaments,  and  even  the  mobility  of  its  component  bones,  all  conduce  to  this  end. 
Suppose,  for  example,  that  a  single  bone  had  occupied  the  place  of  the  seven  bones  in 
the  tarsus,  how  liable  would  this  long  and  cancellated  lever  have  been  to  fractures  from 
the  violent  shocks  to  which  it  is  constantly  exposed,  or  from  the  influence  of  muscular 
contraction  1  The  tarsus  is  narrow  behind,  but  enlarged  before,  so  as  to  increase  the 
transverse  extent  of  the  supporting  base  in  that  direction  ;  it  is  articulated  with  the  leg 
at  a  right  angle,  and,  therefore,  receives  directly  the  weight  of  the  body,  and  as  directly 
transmits  it  to  the  ground.  In  order  to  provide  the  arm  of  a  lever  for  the  power  which 
raises  the  weight  of  the  body,  it  pirojects  behind  the  leg ;  indeed,  the  fitness  of  an  indi- 
vidual for  running  and  leaping  may  be,  in  some  degree,  calculated  from  the  length  of  his 
heel,  or,  what  is  the  same  thing,  from  the  prominence  of  the  tendo  Achilles.  In  stand- 
ing upon  the  sole  of  the  foot,  the  weight  of  the  body  is  transmitted  by  the  tibia  to  the 
astragalus,  and  from  thence  to  the  os  calcis.  Part  of  the  momentum  is  lost  at  the  artic- 
ulation between  these  bones,  and  it  is  easy  to  comprehend  why  they  are  super-imposed, 
and  not  arranged  in  mere  juxtaposition.  But  the  astragalus  is  not  placed  horizontally 
above  the  os  calcis,  for  it  inclines  inward,  downward,  and  forward ;  and  from  this  cir- 
cumstance, even  in  standing  upon  the  soles  of  the  feet,  the  weight  of  the  body  is  distrib- 
uted between  the  os  calcis  and  the  anterior  range  of  the  tarsus,  which  is  itself  subdivi- 
ded into  two  rows,  but  only  on  the  inside,  because  it  is  there  chiefly  that  the  weight  of 
the  body  is  transmitted  by  the  astragalus.  In  one  attitude,  this  weight  is  communicated 
by  the  astralagus  exclusively  to  the  front  row,  viz.,  in  standing  upon  the  point  of  the 
foot ;  and  it  is  then  that  the  division  of  the  tarsus  into  several  bones  is  especially  useful 
in  preventing  the  injurious  effects  of  shocks  transmitted  from  belOw.  There  is  an  im- 
.nense  difference,  also,  as  regards  their  effects  on  the  system,  between  falls  upon  the 
heels  and  those  upon  the  points  of  the  feet. 

The  mechanism  of  the  tarsal  articulations  with  respect  to  mobility  should  be  first  studi 
ed  in  the  two  ranges  separately,  and  afterward  in  the  articulation  of  the  two  rows  to- 
gether. 


tT4  ARTHROLOGY. 

1.  The  bones  of  the  first  range,  viz.,  the  astragalus  and  the  os  calcis,  glide  upon  each 
other  from  before  backward  and  from  side  to  side.  The  lateral  glidings  assist  in  the 
torsion  of  the  foot,  which,  however,  is  chiefly  performed  at  the  articulation  between  the 
two  rows.  The  antero-posterior  glidings  take  place  under  the  following  circumstances : 
when  the  weight  of  the  body  presses  upon  the  upper  part  of  the  astragalus  this  bone  slips 
a  little  forward,  and  the  foot  has  a  tendency  to  become  elongated,  or  flattened  from  above 
downward,  as  Camper  has  remarked.  "WTien  the  pressure  ceases,  the  astragalus  returns 
to  its  original  position.  The  truth  of  the  assertion,  that  the  foot  is  an  elastic  arch,  is 
chiefly  established  by  reference  to  the  nature  of  the  astragalo-calcanian  joint. 

2.  The  bones  of  the  second  row  are  capable  of  such  very  slight  gliding  movements, 
that  they  may  be  considered  as  forming  but  a  siilgle  piece.  However,  the  articulation 
between  the  scaphoid  and  the  cuneiform  bones  is  somewhat  more  movable  than  those 
of  the  cuneiform  bones  with  each  other-and  with  the  cuboid. 

3.  The  chief  movements  of  the  tarsus  take  place  between  the  two  rows,  and  the  ar- 
ticular surfaces  are  there  very  favourable  to  mobility ;  for  there  is  in  one  part  a  head  re- 
ceived into  a  cavity  (at  the  astragalo-scaphoid  articulation),  and  in  another  a  mutual  re- 
ception (at  the  calcaneo-cuboid  articulation).  These  movements  consist  of  a  sort  of  tor- 
sion or  rotation,  by  means  of  which  the  sole  of  the  foot  is  carried  either  inward  or  out- 
ward. Assisted  by  slight  lateral  motions  of  the  astragalo-calcanian  joint,  they  consti- 
tute what  is  called  adduction  and  abduction  of  the  foot.  They  are  generally  attributed  to 
the  ankle-joint ;  but,  as  we  have  seen,  that  articulation  is  limited  to  flexion  and  exten- 
sion ;  the  sprains,  therefore,  which  result  from  too  extensive  movements,  either  outward 
or  inward,  take  place  at  the  articulation  of  the  two  tarsal  ranges,  and  not  at  the  ankle- 
joint.  When  the  movement  of  torsion  is  carried  too  far,  the  external  malleolus  is  forced 
somewhat  outward ;  slight  gliding  motions  occur  at  the  tibio-fibular  articulations  ;  the 
elasticity  of  the  fibula  is  called  into  play ;  and,  if  the  violence  be  immoderate,  the  fibula 
is  fractured. 

Tarso-mktatarbal  Articulations  {Jigs.  82  to  84). 

,  In  the  formation  of  these  joints,  the  wedge-shaped  tarsal  extremity  of  each  metatarsal 
bone  is  opposed  to  one  of  the  bones  of  the  tarsus,  the  corresponding  surfaces  being  plane 
and  triangular.  The  first  metatarsal  bone  articulates  with  the  first  cuneiform ;  the  sec- 
ond metatarsal  with  the  second,  and  shghtly  with  the  first  and  the  third  cuneiform  bones ; 
the  third  metatarsal  with  the  third  cuneiform ;  the  fourth  and  fifth  metatarsal  with  the 
cuboid.  From  this  there  results  an  angular  articular  line,  commencing  on  the  outside,  at 
the  projection  formed  by  the  tuberosity  of  the  fifth  metatarsal  bone.  This  line  is  directed 
obliquely  forward  and  inward  ;  it  forms  an  angle  at  the  third,  and  again  more  particularly 
at  the  second  metatarsal  bone,  because  the  third  cuneiform  bone  projects,  and  is  wedged 
in  between  the  second  and  fourth  metatarsal  bones,  while  the  second  metatarsal  bone 
projects  into  the  tarsus  between  the  first  and  the  third  cuneiform  bones.  The  articular 
surfaces  are  held  together  by  dorsal,  plantar,  and  interosseous  ligaments.  We  shall  now 
study  each  of  these  articulations  separately. 

Articulation  of  the  First  Metatarsal  Bone  with  the  Tarsus. — ^There  are  two  semilunar 
facettes  in  this  articulation,  one  belonging  to  the  first  metatarsal,  the  other  to  the  first 
cuneiform  bone  ;  the  long  diameter  of  these  surfaces  is  directed  vertically.  The  strength 
of  the  joint  is  maintained  by  a  very  strong  plantar  {ffigs.  82  and  84),  and  a  thinner  dor- 
sal {p,fig-  83,  and  e,fig.  84)  ligament.  Both  these  consist  of  bands  directed  from  before 
backward.  There  is  a  distinct  synovial  membrane  for  this  joint.  We  may  include 
among  the  ligaments  of  this  articulation  the  aponeurotic  expansion  given  off  by  the  pe- 
roneus  longus  to  the  first  cuneiform  bone,  and  also  that  derived  from  the  tibialis  anticus, 
and  attached  to  the  first  metatarsal  bone. 

The  articulation  of  the  second  metatarsal  hone  with  the  tarsus  is  effected  by  the  reception 
of  the  posterior  extremity  of  that  bone  within  the  recess  formed  by  the  three  cuneiform 
bones.  We  met  with  a  similar  arrangement,  though  less  perfectly  developed,  in  the 
carpo-metacarpal  articulation  of  the  second  metacarpal  bone.  It  is  the  strongest  of  all 
the  joints  of  this  kind,  and  is  provided  with,  1.  Three  dorsal  ligaments,  as  in  the  corre- 
sponding articulation  in  the  hand ;  one  median  (r,  fig.  83),  broad,  and  constantly  divided 
into  two  bands,  which  proceed  from  the  second  cuneiform  bone ;  a  very  strong  internal 
ligament,  extending  from  the  first  cuneiform  bone,  the  third  being  external,  thin,  and  at- 
tached to  the  third  cuneiform  bone.  2.  With  two  plantar  ligaments,  one  of  which  {g,  fig. 
82)  is  very  strong,  extends  obliquely  from  the  first  cuneiform  to  the  second  metatarsal 
bone,  and  is  prolonged  upward,  so  as  to  become  interosseous ;  the  other  is  very  small, 
and  proceeds  from  the  sharp  edge  of  the  second  cuneiform  to  the  second  metatarsal  bone. 
3.  With  an  interosseous  or  lateral  ligament,  extending  from  the  external  lateral  surface  of 
the  first  cimeiform  bone  to  the  internal  lateral  surface  of  the  second  metatarsal  bone. 

The  articulation  of  the  third  metatarsal  hone  with  the  tarsus  is  maintained  by  a  dorsal  liga- 
ment {s,  fig.  82)  from  the  third  cuneiform  bone.  There  is  no  plantar  ligament,  properly 
so  called,  unless  an  oblique  bundle  of  fibres  from  the  first  cuneiform  bone  be  considered 
as  such ;  but  the  fibrous  layer,  which,  after  forming  the  sheath  of  the  tendon  of  the  pe- 


ARTICULATIONS    OP    THE    METATARSUS.  ITII 

roneus  longus,  is  prolonged  to  the  third  metatarsal  bone,  appears  to  me  to  act  as  a  plantar 
ligament.  There  is  also  an  external  lateral  or  interosseous  ligament,  which  separates  the 
articulations  of  the  third  and  fourth  metatarsal  bones. 

The  fourth  and  fifth  metatarsal  bones  together  present  a  slightly  concave  surface,  which 
articulates  with  the  convex  surface  of  the  cuboid.  The  means  of  union  consist  of  a 
dorsal  ligament  (t,  fig.  83)  for  the  fourth,  and  an  oblique  ligament  (u),  running  outward  and 
forward,  for  the  fifth  metatarsal  bone :  they  are  both  loose,  but  especially  the  latter. 
There  is  no  plantar  hgament,  excepting  the  sheath  of  the  tendon  of  the  peroneus  longus, 
and  a  very  strong  tendinous  expansion  of  the  tibialis  posticus.  The  tendon  of  the  pe- 
roneus brevis  acts  as  an  external  lateral  ligament ;  and,  besides  this  tendon,  there  ex- 
ists a  very  strong  fibrous  band,  derived  from  the  external  plantar  aponeurosis,  which 
extends  from  the  os  caleis  to  the  process  of  the  fifth  metatarsal  bone  ;  and,  moreover, 
an  expansion  of  the  tendon  of  the  peroneus  longus,  given  off  as  it  passes  over  the  cuboid. 
The  articulation  of  the  fifth  metatarsal  bone  is  very  loose.  There  is  a  very  strong  in- 
terossemis  ligament,  stretched  from  the  external  lateral  facette  of  the  third  cuneiform 
bone  to  the  internal  lateral  facette  of  the  fourth,  and  the  external  lateral  facette  of  the 
third  metatarsal  bones.  This  ligament  is  analogous  to  one  that  separates  the  articula- 
tion of  the  fourth  and  fifth  metacarpal  bones  from  the  other  carpo-metacarpal  articula- 
tions, and  it  fulfils  a  similar  purpose  here  ;  so  that  there  are  three  distinct  articulations 
between  the  tarsus  and  the  metatarsus,  and,  therefore,  three  separate  synovial  mem- 
branes ;  one  for  the  fourth  and  fifth  metatarsal  bones,  one  for  the  second  and  third,  and 
another  for  the  first. 

Articulations  of  the  Tarsal  Extremities  of  the  Metatarsal  Bones. — These  are  true  amphi- 
arthroses.  The  corresponding  surfaces  are  partly  contiguous  and  partly  continuous.  The 
contiguous  part  is  nearer  to  the  tarsus ;  it  is  flat,  and  presents  on  each  bone  two  small 
secondary  facettes.  Contrary  to  what  obtains  in  the  metacarpus,  the  continuous  por- 
tions are  larger  than  the  articular  surfaces.  There  are  interosseous,  dorsal,  and  plantar 
ligaments.  The  interosseous  consist  of  very  strong,  short,  and  compact  bundles  of  fibres, 
which  extend  between  the  rough  surfaces  of  two  neighbouring  metatarsal  bones.  The 
dorsal  {b,  fig.  83)  and  plantar  {i,  fig.  82)  pass  transversely  from  one  metatarsal  bone  to 
another,  the  plantar  being  much  the  larger. 

Articulations  of  the  Digital  Extremities  of  the  Metatarsal  Bones. — ^Although  the  digital 
ends  of  these  bones  do  not  articulate  together,  yet,  as  they  are  in  contact  and  move  upon 
each  other,  a  synovial  membrane  covers  the  continuous  surfaces  and  facilitates  their 
movements  ;  a  ligament,  also,  the  transverse  ligament  of  the  metatarsus  (x,  figs.  82  and 
83),  is  stretched  transversely  in  front,  and  unites  them  loosely  together.  This  ligament 
is  conamon  to  the  five  metatarsal  bones  ;  it  is  formed  by  the  junction  of  all  the  anterior 
ligaments  of  the  metatarso-phalangal  articulations,  by  means  of  small  bundles  passing 
from  one  to  another.     It  is  exposed  by  opening  the  sheaths  of  the  flexor  tendons. 

Mechanism  of  the  Metatarsal  Articulations. 

With  regard  to  Strength. — 1.  The  five  component  bones  of  the  metatarsus  are  so  strong- 
ly united  that  it  is  very  uncommon  for  one  of  them  to  be  broken  by  itself;  the  metatar- 
sus, therefore,  can  be  only  fractured  by  violence  sufficient  to  crush  it.  2.  The  slight 
■  mobility  of  the  bones  also  concurs  in  increasing  the  strength  of  this  part  of  the  foot,  by 
permitting  it  to  yield  slightly  to  external  impulse.  3.  The  metatarsus  is  not  uniformly 
strong  throughout ;  the  first  of  its  bones  is  the  strongest,  and  upon  it  a  great  portion  of 
the  weight  of  the  body  rests  during  standing. 

The  mobility  possessed  by  the  tarsal  and  the  digital  extremities  of  the  metatarsal 
bones  requires  to  be  separately  noticed. 

1.  In  the  tarsal  extremities,  the  a'ngular  arrangement,  the  mutual  wedging  of  the  tar- 
sus and  the  metatarsus,  as  well  as  the  strength  and  shortness  of  the  external  and  inter- 
osseous ligaments,  admit  of  only  very  obscure  gliding  movements ;  a  proof  of  which  ex- 
ists in  the  fact,  that  no  example  of  the  luxation  of  these  bones  upon  the  tarsus  has,  per- 
haps, ever  been  recorded.  2.  Obscure,  however,  as  these  movements  may  be,  they  give 
rise  to  considerable  motions  in  the  digital  ends  of  the  bones,  where  the  mobility  is  fa- 
voured by  the  looseness  of  the  transverse  metatarsal  ligament,  and  the  presence  of  a  sy- 
novial membrane  between  the  heads  of  the  bones.  The  first  metatarsal  bone  is  not 
more  movable  than  the  others,  contrasting  remarkably  in  this  respect  with  the  first  met 
acarpal  bone. 

Articulations  op  the  Toes  {figs.  82  to  84). 
Metatarso-phalangal  Articulations. 
These  articulations  belong  to  the  class  condyloid,  and  offer  a  nearly  perfect  similarity 
to  the  metacarpo-phalangal  joints. 

Articular  Surfaces. — The  head  of  each  metatarsal  bone  is  flattened  on  the  sides,  and 
elongated  from  above  downward,  so  that  it  forms  a  condyle.  Each  i)halanx  presents  3 
shallow  cavity,  the  greatest  diameter  of  which,  contrary  to  that  of  the  metatarsal  surface 
is  transverse. 


J 76  ARTHROLOGY. 

Means  of  Union. — 1.  There  is  an  inferior  or  glenoid  ligament  (I,  Jig.  82),  situated  on  the 
plantar  aspect  of  the  joint ;  it  is  very  thick,  of  the  density  of  cartilage,  and  consists  of 
interlacing  fibres  :  its  edges  are  continuous,  partly  with  the  sheath  of  the  flexor  tendons, 
partly  with  the  transverse  metatarsal  ligament,  but  especially  with  the  lateral  ligaments 
of  the  joint.  It  is  grooved  below  for  the  flexor  tendons,  concave  above,  to  correspond 
with  the  convexity  of  the  head  of  the  metatarsal  bone,  and  completes  the  cavity  in  which 
that  head  is  received.  Its  anterior  edge  is  very  firmly  fixed  to  the  plantar  border  of  the 
cavity  of  the  phalanx,  of  which  it  seems  a  continuation ;  its  posterior  edge  is  free,  or, 
rather,  is  loosely  connected  by  some  ligamentous  fibres  to  the  inequalities  behind  the 
head  of  the  metatarsal  bone,  upon  the  contracted  neck  of  which  it  is  moulded  very  ex- 
actly, so  that,  while  protecting  the  lower  part  of  the  joint,  it  serves  also  to  increase  the 
extent  of  the  surfaces  included  in  the  articulation.  2.  There  are  two  very  strong  lateral 
ligaments  (y,  figs.  82  and  83),  an  internal  and  an  external,  inserted,  not  into  the  depres- 
sions on  each  side  of  the  head  of  the  metatarsal  bone,  but  into  tubercles  situated  behind 
them ;  from  this  origin  they  proceed  very  obliquely  forward  and  downward,  like  flat 
bands,  spreading  out  as  they  advance,  and  terminating  partly  in  the  inferior  ligament, 
and  partly  on  the  sides  of  the  phalanx.  There  is  no  dorsal  ligament,  properly  so  called, 
but  the  corresponding  extensor  tendon  evidently  occupies  its  place.  It  is  not  uncommon 
to  observe  a  prolongation  from  the  anterior  surface  of  this  tendon  united  to  the  metatar- 
sal end  of  the  first  phalanx. 

Synovial  Capsule. — ^Under  the  extensor  tendon  we  find  a  very  loose  synovial  capsule ; 
it  covers  the  internal  surface  of  the  ligaments  as  well  as  the  articular  cartilages. 

The  metatarso-phalangal  articulation  of  the  first  metatarsal  bone  presents  some  peculiar- 
ities which  merit  special  description.  1.  The  articular  surfaces  are  much  larger  than  in 
the  other  similar  joints.  2.  The  head  of  the  first  metatarsal  bone  presents  two  pulleys 
on  its  plantar  aspect,  separated  from  each  other  by  a  prominent  ridge  directed  from  be- 
fore backward.  This  construction  is  connected  with  the  presence  of  two  sesamoid  bones 
{g,  fig.  84),  developed  in  the  substance  of  the  inferior  ligament,  which  is  three  or  four 
times  thicker  than  in  the  other  joints.  The  lateral  ligaments  are  almost  exclusively 
fixed  into  these  sesamoid  bones.  This  joint  has  also  a  sort  of  fibrous  ring  surmounting 
the  border  of  the  glenoid  cavity  of  the  phalanx. 

Articulations  of  the  Phalanges  of  the  Toes. 

These  are  perfect  angular  ginglymi.  Each  toe  has  two  such  joints,  with  the  excep- 
tion of  the  great  toe,  which  has  only  one. 

Articular  Surfaces. — The  anterior  extremity  of  the  first  phalanx,  flattened  from  above 
downward,  presents  a  trochlea,  which  is  broader,  and  prolonged  farther  on  the  plantar 
than  on  the  dorsal  surface.  On  the  second  phalanx  there  are  two  small  glenoid  cavities 
separated  by  a  ridge,  the  cavities  corresponding  to  the  sm£dl  condyles,  and  the  ridge  to 
the  groove  of  the  trochlea  just  described. 

Ligaments. — 1.  As  the  articular  pulley  of  the  first  phalanx  projects  considerably  below 
the  second,  it  is  covered  in  this  direction  by  an  inferior  or  glenoid  ligament  (m,  fig.  82), 
exactly  resembling  those  of  the  metatarso-phalangal  joints,  and  perfoming  the  same 
functions.  2.  The  two  lateral  ligaments  (y,  figs.  82  and  83)  are  fixed  precisely  like  the 
corresponding  ligaments  of  the  metatarso-phalangal  joints,  viz.,  into  the  tubercle  above 
the  lateral  hollow  on  the  anterior  extremity  of  the  first  phalanx ;  and  they  extend  ob- 
liquely forward  to  the  glenoid  ligament  and  the  second  phalanx.  3.  There  is  no  superior 
ligament,  its  place  being  supplied  by  the  extensor  tendon.  This  tendon  is  arranged  in  a 
particular  manner,  for  it  frequently  sends  off  a  prolongation  (z,  fig.  83)  from  its  anterior 
surface,  which  is  attached  to  the  upper  end  of  the  second  phalanx.  4.  The  synovial  cap- 
sule is  arranged  as  in  the  metatarso-phalangal  articulations.  There  is  often  a  sesamoid 
bone  in  the  inferior  ligament  of  the  phalangal  articulation  of  the  great  toe. 

Mechanism  of  the  Metatarso-phalangal  Articulations. 
Like  all  condyloid  joints,  these  admit  of  movements  in  four  principal  directions,  and, 
therefore,  are  also  capable  of  circumduction.  Extension  or  flexion  backward  can  be  car- 
ried much  farther  than  in  any  other  similar  joints.  The  lateral  movements  of  abduction 
and  adduction  are  very  hmited.  Let  us  examine  what  takes  place  during  each  of  these 
movements,  in  which  the  glenoid  cavity  of  the  first  phalanx  glides  upon  the  head  of  the 
corresponding  metatarsal  bone.  Inflexion,  the  first  phalanx  glides  downward  upon  the 
head  of  the  metatarsal  bone  ;  the  extensor  tendon  and  the  upper  part  of  the  synovial 
capsule  are  stretched  by  the  projecting  head  ;  the  upper  fibres  of  the  laterad  ligaments 
are  also  stretched ;  these  fibres  then  limit  the  motion,  which,  nevertheless,  may  be  car- 
ried so  far  that  the  phalanx  may  make  a  right  angle  with  the  metatarsal  bones.  In 
extension,  the  phalanx  glides  upward  upon  the  head  of  the  corresponding  metatarsal 
bone ;  the  superior  fibres  of  the  lateral  ligaments  are  relaxed,  while  the  inferior  are 
stretched :  these  latter  and  the  inferior  ligament  evidently  limit  the  motion.  In  all  sub- 
jects it  maybe  carried  so  far  as  to  make  an  obtuse  angle  behind  ;  in  some  so  as  even  to 
form  a  right  angle.  The  movements  of  abduction  and  adduction  are  limited  by  the  meet- 
ing of  the  toes. 


ODONTOLOGY.  177 

Mechanism  of  the  Phdangal  Articulations. 
As  the  mechanism  of  these  joints  is  in  every  respect  identical  with  that  of  the  fingers, 
we  shall  refer  to  what  has  been  said  upon  that  subject,  merely  remarking  that,  eithei 
from  original  construction,  or  from  the  continued  confinement  of  the  toes  in  tight  shoes, 
their  movements,  which  consist  exclusively  of  flexion  and  extension,  are  much  more 
limited  than  those  of  the  fingers. 

Note  on  Artkrology. — [It  has  been  considered  advisable  to  include  in  a  single  note  the  following  observation* 
on  the  general  anatomy  of  the  several  tissues  that  enter  into  the  construction  of  the  articulations : 

Cartilages  (p.  111). — The  substance  of  the  articular  cartilages,  in  many  joints,  appears  to  be  arr'mged  in 
masses  placed  side  by  side,  and  perpendicularly  to  the  surface  of  the  bone  ;  and  hence  the  fibrous  character 
presented  by  them  alter  slight  maceration:  nevertheless,  they  are  composed  of  pure  cartilage,  unmixed  with 
fibrous  tissue.  When  viewed  under  the  microscope,  cartilage  is  found  to  consist  of  a  transparent  substance, 
in  which  are  imbedded  numerous  corpuscles,  either  placed  singly  or  aggregated  in  groups.  The  interme- 
diate substance  is  homogeneous  in  youth,  but  becomes  more  or  less  laminated  as  age  advances.  The  corpuscles, 
which  are,  in  fact,  metamorphosed  primitive  cells,  are  of  irregular  forms,  contain  nuclei  and  nucleoli,  and  are 
somewhat  flattened  near  the  surface  of  the  cartilage.  Occasionally,  several  are  seen  occupying  a  distinct 
cavity  in  the  intermediate  substance.  Their  average  size  is  tsVs*^  °^  '"^  '"'^'^  '"  length,  by^ iAj-jth  in 
breadth.  Neither  nerves,  bloodvessels,  nor  lymphatics  are  found  in  the  articular  cartilages,  which,  al- 
though non-vascular,  can  scarcely  be  considered  unorganized.  Cartilage  contains  66  per  cent,  of  water ;  its 
principal  solid  constituent  is  an  animal  matter,  resolved  by  boiling  into  a  peculiar  variety  of  gelatin,  called 
chondrin ;  it  also  contains  salts  of  soda,  lime,  magnesia,  and  potash. 

The  inter-articular  cartilages  having  free  surfaces  (as  those  of  the  knee-joint),  are  composed  of  true  carti- 
lage interwoven  with  fibrous  tissue,  which  particularly  abounds  at  their  attached  margins.  The  inter-verte- 
bral substances,  and  all  other  interosseous  cartilages,  have  a  similar  structure,  but  contain  a  greater  propor- 
tion of  fibrous  tissue.  From  the  two  anatomical  elements  of  which  these  structures  consist,  they  are  called 
ftbro-cartilages. 

The  articular  borders  surrounding  the  glenoid  and  cotyloid  cavities,  generally  described  with  the  ligaments, 
are  also  composed  of  fibro-cartilaginous  tissue. 

Ligaments  (p.  112). — The  articular  ligaments  consist  entirelyof  fibrous  tissue,  the  obvious  component  fibres 
of  which  are  divisible  into  parallel  microscopic  filaments,  exactly  similar  to  those  of  cellular  tissue  (see  note 
on  Aponeurologt,  infra).  They  are  supplied  with  but  very  few  vessels  and  nerves  ;  they  contain  62  per 
cent,  of  water,  the  remainder  being  almost  entirely  converted  into  gelatin  by  boiling. 

The  yellow  elastic  tissue,  of  which  the  ligamenta  subflava  are  composed,  differs  in  minute,  as  well  as  in  ob- 
vious characters,  from  the  white  fibrous  tissue  of  ordinary  ligaments,  it  consists  chiefly  of  peculiar  filaments, 
intermixed  with  a  few  of  those  of  cellular  tissue.  The  proper  elastic  filaments,  examined  with  the  micro- 
scope, are  yellowish  and  transparent,  have  a  bright  aspect  and  dark  outline  (very  unlike  the  delicate  appesir- 
ance  of  the  cellular  filaments),  and  are  usually  curved  or  bent  at  their  torn  extremities.  The  peculiar  char- 
acter of  dividing  and  uniting  again,  often  assigned  to  them,  is  thought  to  be  rather  apparent  than  real,  and  to 
depend  on  an  imperfect  separation  of  the  larger  into  their  component  filaments.  The  elastic  is  more  vascular 
than  the  fibrous  tissue.  It  contains  less  water  (only  29  per  cent.),  and  yields  much  less  gelatin  when  boiled  ; 
the  insoluble  residua  somewhat  resembles  coagulated  albumen. 

Synovial  Membranes  (p.  112). — The  basis  of  an  articular  synovial  membrane  is  cellular  tissue,  which  be- 
comes more  and  more  condensed  towards  the  free  surface  of  the  membrane.  The  smoothness  of  this  surface  is 
due  to  a  covering  of  flattened  scales  (metamorphosed  primitive  cells)  lying  upon  it,  and  constituting  what  is 
termed  an  epithelium.  The  recent  discovery  of  this  epithelium  upon  the  surface  of  the  articular  cartilages  is 
suflScient  to  establish  the  continuity  of  the  synovial  membrane  over  them;  a  fact  which,  though  doubted  by 
many,  is  assumed  by  M.  Cruveilhier  upon  ansilogical  grounds.  No  nerves  have  been  traced  into  these  mem- 
branes, and  the  vessels  existing  in  the  sub-synovial  tissue  cease  at  the  margin  of  the  cartilage.  The  synovia 
secreted  by  these  membranes  is  an  aqueous  solution  of  albumen  and  saline  matters.  It  contains  more  albu- 
men than  the  fluid  of  serous  cavities,  the  lining  membranes  of  which  (as  we  shall  hereafter  notice)  have  a 
similar  structure  to  those  just  described. 

Besides  the  articular  synovial  membranes,  two  other  kinds  are  usually  mentioned,  viz.,  the  bursal,  including 
the  various  bursae,  erroneously  called  bursae  mucosae  ;  and  the  vaginal,  examples  of  which  are  met  with  in  th« 
sheaths  of  tendons.     These  two  forms  will  be  again  referred  to  in  the  note  on  Aponeurology,  infra. 

Adipose  Tissue. — The  constant  occurrence,  especially  in  the  larger  articulations,  of  masses  of  fat  beneath 
the  synovial  membranes,  affords  an  opportunity  of  jdluding  in  this  place  to  the  minute  anatomy  of  the  adipose 
tissue  generally.  It  may  be  briefly  stated  to  consist  of  an  aggregation  of  distinct  spherical  or  oval  vesicles, 
containing  the  adipose  substance,  and  having  numerous  vessels  ramifying  on  their  transparent  and  homoge 
neous  parietes.  They  are  held  together  by  the  branches  of  those  vessels,  and  by  cellular  tissue.  In  man,  the 
adipose  substance  is  liquid  during  life,  but  separates,  when  obtained  in  any  quantity,  into  an  oily  fluid  caUed 
•la'ine,  and  a  solid  residue,  consisting  of  two  fatty  substances,  stearine  and  margarine.] 


ODONTOLOGY. 


Circumstances  in  which  the  Teeth  differ  from  Bones. — Number. — Position. — Exterrud  Confot 
mation.  — General  Characters.  — Classification — Incisor — Canine — Molar. — Structure. — 
Development. 

The  teeth,  the  immediate  instruments  of  mastication,  are  those  ossiform  concretions 
which  surmount  the  edges,  and  are  implanted  in  the  substance  of  both  jaws.  The  teeth 
are  not  bones,  though,  from  possessing  an  apparent  analogy  to  them,  they  have  long 
been  considered  as  such.     They  differ  from  bones  in  many  respects. 

1.  With  regard  to  position.  The  teeth  are  naked  and  visible  at  the  surface,  while  the 
bones,  and  tliis  is  one  of  their  most  important  characters,  are  covered  by  periosteum. 

2.  In  anatomical  characters.  The  teeth  consist  of  a  bulb  or  thick  papilla,  surrounded 
by  a  calcareous  envelope,  composed  of  two  substances,  the  enamel  and  the  ivory.  This 
calcareous  envelope  is  not  traversed  by  vessels,  nor  can  any  trace  of  cellular  tissue  be 
discovered  in  it. 

3.  In  regard  to  their  mode  of  development.  In  the  teeth,  the  formation  of  the  hard  or 
ossiform  matter  takes  place  by  successive  depositions,  from  the  circumference  to  the  cen- 

Z 


178  ODONTOLOGY. 

Ire ;  while  bones  are  developed  in  a  precisely  opposite  direction.  No  nutritive  changes 
are  carried  on  in  the  teeth  as  in  bones.  Moreover,  the  teeth  are  renewed  by  means  of 
the  second  dentition ;  but  there  is  no  analogous  phenomenon  in  the  development  of  bone. 

4.  In  physiological  relations.  The  teeth  do  not  participate  in  the  diseases  of  bone, 
being  susceptible  only  of  chemical  and  physical  alterations ;  nor  is  the  period  of  their 
existence,  like  that  of  the  bones,  of  equal  duration  with  the  life  of  the  individual. 

5.  In  regard  to  chemical  composition.  They  contain  a  much  larger  proportion  of  saline 
matters,  and  the  enamel  is  entirely  destitute  of  gelatine. 

All  these  circumstances  prove  that  the  teeth  are  not  bones.  We  shall  now  show  that 
they  belong  to  the  epidermoid  system,  and  are  analogous  to  the  nails  and  hair. 

1.  When  examined  in  the  lower  animals,  they  are  found  to  present  an  uninterrupted 
series,  from  such  as  closely  resemble  horns  or  nails  to  such  as  present  the  most  perfect- 
ly characteristic  appearances  of  bone.  2.  They  have  a  lamellated  structure,  hke  the  nails 
and  hair :  in  some  animals  this  is  very  manifest,  but  is  rendered  obscure  in  others  from 
the  abundance  of  calcareous  deposite.  3.  They  are  developed  in  the  same  manner  as 
horns,  nails,  and  hair.  4.  Like  them,  they  present  no  nutritive  phenomena  ;  they  are 
formed  layer  after  layer,  and  undergo  no  renewal  of  their  constituent  parts  ;  they  are* 
inorganic  bodies,  the  products  of  transudation.  5.  According  to  M.  Geoffrey  St.  Hilaire, 
the  beak  of  birds,  which  is  evidently  a  horny  structure,  belongs  to  the  dental  system. 

Number. — In  young  subjects,  at  the  period  of  the  first  dentition,  there  are  twenty  teeth, 
ten  in  each  jaw :  in  the  adult  there  are  thirty-two,  sixteen  in  each  jaw.  Man,  therefore, 
during  the  course  of  his  life,  has  fifty-two  teeth,  twenty  temporary,  and  thirty-two  per- 
manent. 

The  varieties  in  the  number  of  the  teeth  are  either  the  result  of  a  deficiency  or  an  excess. 

The  varieties  from  deficiency  consist,  1 .  In  the  absence  of  all  teeth,  examples  6f  which 
have  been  recorded  by  Fox  and  Sabatier ;  2.  In  the  absence  of  a  great  number  of  teeth, 
as  occurred  in  an  individual  who  had  only  the  four  incisors  in  each  jaw.  These  deficien- 
cies are  chiefly  observed  to  affect  the  posterior  molares,  and  frequently  they  are  merely 
apparent  in  them  from  the  teeth  remaining  concealed  within  the  alveoli  for  a  much  longer 
period  than  usual.  Besides,  Fox  remarks,  that  there  is  no  tooth  which  has  not  occa- 
sionally been  observed  to  be  wanting,  either  alone  or  in  conjunction  with  others. 

The  varieties /rom  excess  are  observed  in  the  existence  of  supernumerary  teeth,  which 
may  or  may  not  range  wth  the  ordinary  teeth.  The  supernumerary  teeth  either  exist  in 
distinct  alveoli,  or  are  blended  with  some  other  teeth.  There  are  two  varieties  of  this 
latter  condition  ;  for  the  supernumerary  tooth  may  either  appear  to  grow  upon  a  primitive 
or  parent  tooth  {^dens  prolifcr  of  Bartholin),  or  several  teeth  may  seem  as  if  united  into  one. 

Position. — The  teeth  are  arranged  in  two  parabolic  curves,  constituting  the  dental 
arches,  and  corresponding  to  the  alveolar  arches,  which  support  them.  Into  these  arches 
the  teeth  are  fixed,  not  by  articulation,  but  by  the  implantation  of  their  roots  into  the  al- 
veoli, which  are  moulded  exactly  upon  them.  This  arrangement  induced  those  anato- 
mists who  regarded  the  teeth  as  true  bones  to  admit  a  peculiar  mode  of  articulation  for 
them,  called  gomphosis  (yd/z^of,  a  nail). 

The  teeth  are  mechanically  fixed  in  their  alveoli ;  but  yet  we  must  consider  the  gums 
and  the  alveolo-dental  periosteum  as  also  forming  uniting  media.  The  importance  of  the 
latter  will  be  acknowledged,  if  we  consider  the  effects  of  scurvy  in  loosening  the  teeth, 
and  the  ease  with  which  they  drop  out  from  the  skeleton. 

Each  dental  arch  forms  a  regular,  uninterrupted  curve,  an  aiTangement  peculiar  to  man, 
for  in  the  lower  animals  the  teeth  are  of  unequal  length,  and  the  dental  arches  have  irreg- 
ular edges ;  moreover,  instead  of  their  teeth  being  uninterruptedly  contiguous,  very  con- 
siderable intervals,  at  some  points  at  least,  are  left  between  them.  Each  dental  arch 
presents  an  anterior  convex,  and  a  posterior  concave  surface  ;  an  adherent  or  alveolar  bor- 
der, which  is  regularly  scalloped  ;  and  a  free  edge,  thin  and  cutting  at  the  middle,  thick 
and  tubercular  at  the  sides  ;  in  the  latter  situations  it  has  two  lips,  of  which  the  external 
is  sharper  in  the  upper  teeth,  and  the  internal  in  the  lower.  The  free  edge  is  so  arran- 
ged that  all  the  teeth  are  upon  a  level. 

As  the  superior  dental  arch  forms  a  greater  curve  than  the  inferior,  it  necessarily  fol- 
lows that  the  two  arches  meet  hke  the  blades  of  a  pair  of  scissors  ;  but  the  mode  in 
which  they  meet  is  not  the  same  in  the  middle  region,  occupied  by  the  incisor  teeth,  as 
on  the  sides,  where  the  molares  are  placed.  Thus,  the  upper  incisors  pass  in  front  of 
the  lower,  while  the  external  tubercles  of  the  superior  molares  pass  to  the  outside  of  the 
external  tubercles  of  the  inferior  molares,  so  that  these  latter  tubercles  are  applied  to  the 
furrow  formed  between  the  two  rows  of  tubercles  of  the  upper  molares. 

The  teeth  of  the  upper  jaw,  with  the  exception  of  the  great  molaies,  are  larger,  in  gen- 
eral, than  those  of  the  lower.  I  should  also  remark,  that  no  tooth  is  placed  quite  per- 
pendicularly to  its  fellow  in  the  other  jaw ;  for  the  summit  of  a  tooth  in  one  jaw  always 
corresponds  to  the  interval  between  the  summits  of  two  in  the  other  ;  so  that  the  two 
rows  of  teeth  are  not  simply  in  contact,  but  are  really  locked  together. 

*  See  note,  p.  183. 


THE    INCISOR   TEETH.  179 

External  Conformation. — ^The  teeth,  considered  in  reference  to  their  form  or  configura- 
tion, present  some  general  characters  which  distinguish  them  from  all  other  organs  of  the 
body ;  and  also  certain  specific  characters,  by  which  one  tooth  may  be  distinguished  from 
another. 

General  Characters  {figs.  85  to  92).  —  Each  tooth  is  composed  of  two  very  distinct 
parts  :  a  free  portion,  projecting  beyond  the  alveolus,  named  the  crown  or  body  {a,  figs. 
85,  &c.),  and  a  portion  implanted  in  the  bone  called  the  root  ox  fang  (i),  the  constricted 
portion  between  these  two  constituting  the  neck  (c).  The  rim  of  the  alveolus  or  socket 
does  not  exactly  correspond  to  the  neck  of  the  tooth,  but  rather  to  the  root,  at  some  dis- 
tance from  the  neck,  the  intervening  space  being  occupied  by  the  gam. 

The  axis  of  the  teeth  is  vertical.  This  direction  is  peculiar  to  the  human  species.  The 
projection  of  the  teeth  forward  gives  a  disagreeable  aspect  to  the  countenance,  and  is  al- 
most invariably  connected  with  a  diminution  of  the  facial  angle.  The  axis  of  all  the  teeth 
is  slightly  inchned,  so  as  to  converge  somewhat  towards  the  centre  of  the  alveolar  curve. 

The  length  of  the  teeth  (that  is,  of  their  crowns)  is  very  nearly  uniform.  The  advan- 
tage of  this  arrangement,  in  preventing  one  tooth  from  projecting  beyond  another,  is  very 
obvious.  Wlien  the  teeth  are  not  equal  in  length,  mastication  is  evidently  imperfect ; 
and  therefore  the  principal  object,  in  cases  of  fracture  of  the  lower  jaw,  is  to  prevent  the 
inconvenience  that  would  arise  from  irregularity  of  the  dental  edge,  and  which  is  actu- 
ally observed  when  the  fragments  unite  in  a  wrong  position. 

The  teeth  are  only  separated  from  each  other  by  very  small  triangular  intervals,  so 
that  they  are  almost  contiguous.  When  the  intervcds  are  very  considerable,  mastica- 
tion is  imperfect. 

The  general  form  of  the  teeth  is  that  of  a  sUghtly  elongated  cone,  flattened  in  opposite 
directions,  the  base  of  which  is  formed  by  the  crown  and  turned  towards  the  free  edge 
of  the  dental  arch,  while  the  summit,  formed  by  the  simple  or  compound  root,  presents 
an  opening  that  penetrates  into  the  cavity  of  the  tooth.  The  conical  form  of  the  root, 
and  the  accuracy  with  which  the  alveolus  is  moulded  upon  it,  have  a  twofold  result,  viz., 
that  the  effort  of  mastication  is  disseminated  over  all  points  of  the  socket,  and  that  no 
pressure  is  ever  experienced  at  the  extremity  which  receives  the  vessels  and  nerves. 

The  differences  presented  by  the  teetfi,  more  especially  in  the  crown,  have  led  to  their 
arrangement  into  three  classes,  viz.,  incisors,  canine,  and  molars:  the  latter  have  been 
subdivided  into  the  great  and  small  molars. 

The  crown  of  the  incisor  teeth  {figs.  85,  86)  resembles  a  wedge  with  the  sharp  border 
shaped  like  a  chisel ;  as  their  name  implies,  they  serve  the  purpose  of  cutting  the  food. 
The  crown  of  a  canine  tooth  {figs.  87,  88)  forms  a  cone  with  a  free  pointed  apex ;  these 
teeth  serve  to  tear  the  food,  whence  their  name  of  laniaires :  Hunter  called  them  cu'spi- 
dati,  from  their  having  only  one  point.  The  crown  of  a  molar  tooth  {figs.  89  to  92)  is 
cuboidal,  the  free  extremity  being  provided  with  tubercles  or  points,  intended  to  bruise 
the  food  as  in  a  mill.  The  smjdl  molars,  which  have  only  two  tubercles,  are  called  by 
Hunter  bicuspides  {figs.  89  and  90).  Man  alone,  of  the  entire  animal  series,  is  possessed 
of  the  three  kinds  of  teeth  in  an  almost  equal  state  of  development. 

The  Incisor  Teeth  {jigs.  85  and  86). 

These  are  eight  in  number,  four  in  either  jaw.  They  occupy  the  middle  of  the  dental 
arches,  and,  consequently,  the  anterior  extremity  of  the  lever  of  the  third  order,  repre- 
sented by  each  half  of  the  jaw.  Their  position  is  unfavourable,  and,  consequently,  they 
are  intended  only  to  divide  substances  that  offer  but  little  resistance.  This  class  of  teeth 
attain  their  utmost  development  in  rodentia  ;  as  in  the  rabbit,  beaver,  &c. 

General  Characters. — The  crotcn  (a)  is  wedge-shaped ;  its  anterior  surface  {fig.  85)  is 
convex,  and  the  posterior  concave  ;  its  sides  {fi,g.  86)  are  triangular  ;  its  e--    85     K     86 
base  is  thick  and  continuous  with  the  root,  and  its  free  edge  sharp,  some-     '^' 
what  broader  than  the  base,  and  cut  obUquely  upward  and  backward  in  ,     „r" 
the  upper  teeth,  and  downward  and  forward  in  the  lower.     This  obliqui- 
ty of  the  surfaces,  by  which  the  incisors  of  the  two  jaws  correspond,  is 
the  result  of  their  constant  friction  upon  each  other,  for  they  cross  like 
the  blades  of  scissors.     The  cutting  edge  of  an  incisor  tooth,  before  it  is 
worn  down,  is  marked  by  three  small  denticulations.     The  root  {b)  has 
the  form  of  a  cone  flattened  on  the  sides  ;  the  anterior  border  is  thicker 
than  the  posterior.     A  small  vertical  furrow  (see  fig.  86)  occasionally  ex- 
ists on  each  side,  appearing  to  indicate  an  original  division  ;  and  some- 
times the  point  of  the  root  is  bifid.     Two  curved  lines,  having  their  concavities  directed 
downward,  and  united  on  the  sides  of  the  tooth,  separate  the  root  from  the  crown.* 

Differential  Characters. — The  upper  incisors  are  distinguished  from  the  lowor  by  their 
nmch  greater  size,  the  fonner  being  almost  twice  as  large  as  the  latter.  In  the  upper 
jaw,  the  middle  are  distinguished  from  the  lateral  incisors,  also,  by  their  well-marked  su- 

*  [It  maybe  well  to  observe,  that  the  illustrations  arc  all  taken  from  teeth  of  the  upper  jaw,  in  which  tha 
general  characters  of  each  class  are  more  strongly  marked  than  in  those  of  the  lower.! 


ODONTOLOGY. 


periority  in  size.     In  the  lower  jaw,  on  the  contrary,  the  lateral  incisors  are  the  larger, 
though  the  difference  is  but  shght. 

The  Canine  Teeth  {fgs.  87,  88). 
These  are  four  in  number,  two  in  each  jaw.     They  are  situated  on  either  side  exter- 
nally to  the  incisors,  and  therefore  are  nearer  to  the  fulcrum,  so  that  they  can  overcome 
a  greater  resistance.   These  teeth  are  most  completely  developed  in  the  camivora.    The 
tusks  of  the  boar  and  of  the  elephant  are  also  canine  teeth. 

General  Characters. — They  are  the  longest  of  all  the  teeth,  both  in  the  crown  and  in 
Fig.  87.  Fig.  88.  the  root ;  they  therefore  project  a  little  beyond  the  incisors,  particu- 
larly in  the  upper  jaw.  Their  crown  (a)  is  thick  and  irregularly  conoid  ; 
it  is  somewhat  enlarged  immediately  above  the  neck,  and  terminates 
in  a  blunt  point  cut  obliquely  at  the  sides  (see^^.  88),  and  grooved  be- 
hind. The  anterior  surface  (fig.  87)  is  convex,  the  posterior  concave. 
The  canine  teeth  have  much  longer  and  larger  roots  (ft)  than  any  oth- 
er, and  their  alveoli  are  remarkably  prominent.  The  root  is  flattened 
on  the  sides,  each  of  which  presents  a  vertical  groove  traversing  its 
entire  length  (see^^.  88). 

Differential  Characters. — The  superior  canine  teeth  are  distinguished 
from  the  inferior  by  their  greater  length  and  thickness.  The  roots  cor- 
respond to  the  ascending  process  of  the  superior  maxilla,  and  in  some 
subjects  are  prolonged  to  the  base  of  that  process.  The  length  of  their  root  explains  the 
difficulty  of  extracting  them,  and  the  accidents  by  which  this  operation  is  sometimes  fol- 
lowed. There  are  several  preparations  in  the  museum  of  the  Faculty  of  Medicine,  in 
which  the  canine  teeth  are  seen  developed  in  the  substance  of  the  ascending  process, 
and  reversed,  so  that  the  crown  is  turned  upward  and  the  root  downward. 

The  Molar  Teeth  {fgs.  89  to  92). 
The  molar  teeth  are  twenty  in  number,  ten  in  each  jaw.  They  occupy  the  last  five 
alveoli  on  either  side,  and,  consequently,  are  nearer  to  the  fulcrum  than  all  the  other  teeth  : 
they  are,  therefore,  most  advantageously  placed  for  exercising  a  powerful  pressure  upon 
any  substances  we  may  desire  to  break  between  the  teeth.  The  instinctive  motion  by 
which,  in  order  to  crush  a  very  hard  body,  we  place  it  between  the  molars,  is  evidently 
connected  with  this  arrangement.  These  teeth  are  most  highly  developed  in  herbivora. 
The  general  characters  which  belong  to  all  the  molars  are  the  following :  1.  The  great 
extent  of  their  grinding  surfaces,  which  far  exceed  those  of  the  incisors  and  canine ; 
2.  The  absence  of  all  obliquity  at  their  summit,  the  anterior  and  posterior  surfaces  be- 
ing parallel,  instead  of  approaching  each  other,  so  as  to  form  a  cutting  or  angular  bor- 
der :  this  character  is  evidently  connected  with  the  preceding  one  ;  3.  The  inequalities 
of  their  grinding  surfaces,  which  are  marked  by  eminences  and  depressions  ;  4.  The  round 
or  even  cubical  form  of  the  crown ;  5.  The  shortness  of  the  vertical  dimneter  of  the  crown ; 
6.  The  multiplicity  of  roots. 

The  molars  are  divided  into  two  classes,  according  to  their  difference  in  size,  and  the 
number  of  tubercles  upon  their  grinding  surfaces.  The  smaller  are  called  small  molars, 
or  bicuspides ;  the  larger,  great  molars,  or  multicuspides.  It  should  be  remarked,  that  in 
the  first  dentition,  all  the  molars,  without  exception,  are  multicuspides. 

The  small  molars  or  biscuspides  {figs.  89  and  90)  are  eight  in  number ;  four  in  each 
jaw,  two  on  the  right,  and  two  on  the  left  side.  They  are  distinguished  by  the  names 
first,  second,  &,c.  They  are  situated  between  the  canine  teeth  and  the  great  molars. 
The  small  molars  of  the  upper  jaw  correspond  to  the  canine  fossae. 

General  Characters.  —  The  crown  (a)  is  irregularly  cyhndrical,  flattened  from  before 
Fig.  89.  Fig.  90  backward,  with  its  long  diameter  directed  transversely.  The  anterior 
and  posterior  surfaces,  which  correspond  to  the  two  neighbouring 
teeth,  are  plain  (see  fig.  90).  The  internal  and  external  {fig.  89)  sur- 
faces are  convex ;  the  free  or  grinding  surface  is  armed  with  two  tu- 
bercles or  points,  separated  from  each  other  by  a  furrow.  Of  the  two 
tubercles  the  external  is  the  larger.  The  crown  of  the  small  molars 
has  been  compared  to  that  of  two  small  canine  teeth  united.  The  root 
(b)  is  generally  simple,  but  sometimes  double  or  bifid.  When  simple, 
it  has  a  deep  vertical  groove  upon  each  side  ;  when  it  is  bifid,  the  sep- 
aration is  never  so  deep  as  in  the  great  molars. 
Differential  Characters. — The  lower  bicuspides  are  distinguished  from  the  upper  by 
their  smaller  size,  by  a  slight  projection  of  the  crown  inward,  and  by  the  external  tuber- 
cle being  worn  down.  In  the  upper  bicuspides,  the  two  tubercles  are  separated  by  a 
deep  furrow  ;  in  the  lower,  on  the  contrary,  the  furrow  is  more  shallow,  and  the  tuber- 
cles are  sometimes  united  by  a  ridge.  The  second  upper  bicuspid  has  generally  two 
roots  {figs.  89  and  90),  by  which  it  is  distinguished  from  the  others.  Tlie  first  lower 
bicuspid,  somewhat  smaller  than  the  second,  has  most  commonly  but  one  tubercle,  viz 
the  external.     This  gives  it  more  resemblance  to  a  canine  tooth. 


STRUCTURE    OF    THE   TEETH. 


181 


The  great  molars  or  multicuspides  (figs.  91  and  92)  are  twelve  in  number  ;  six  in  each 
jaw,  three  on  one  side,  and  three  on  the  other.   They  are  named      pig_  gj,  pig  93 

nmnerically,  proceeding  from  before  backward,  first,  second,  and     ^    „  <' 
third.     The  last  is  also  called  de-ns  sapicntia,  on  account  of  its 
tardy  appearance.     They  occupy  the  most  remote  part  of  the 
alveolar  border. 

General  Characters. — The  crown  (a)  is  pretty  regularly  cuboid. 
The  anterior  and  posterior  surfaces  (see  fig.  92),  by  which  these  4  ] 
teeth  correspond,  are  flat ;  the  external  and  internal  surfaces 
(fi,g.  91)  are  rounded.  The  grinding  surface  is  armed  with  four 
tubercles  (dcntes  guadricuspides),  separated  by  a  crucial  furrow, 
which  is  occasionally  replaced  by  small  depressions.  lu  some  teeth  a  fifth  tubercle  may 
be  found.  In  almost  all  the  tubercles  are  of  unequal  size,  and  cut  into  facettes.  The 
crown  of  the  great  molars  resembles  two  small  molars  united.  The  root  (b)  is  always 
compound ;  it  is  most  commonly  double  or  triple,  and,  in  this  case,  one  of  the  roots  has 
a  longitudinal  furrow.  Sometimes  it  is  divided  into  four  or  five  parts,  variable  both  in 
length  and  direction.  The  roots  are  either  divergent  or  parallel ;  and  occasionally,  after 
separating,  they  approach  each  other  again,  curving  like  hooks,  so  as  to  embrace  a  more 
or  less  considerable  portion  of  the  jaw  bone.  Such  teeth  (which  are  called  dents  harries) 
it  is  impossible  to  extract  without  pulling  away  the  included  portion  of  the  jaw  also. 
Each  root  of  these  teeth  exactly  resembles  the  single  roots  of  the  teeth  already  descri- 
bed, with  the  exception  of  being  smaller. 

Differential  Characters  of  the  Upper  compared  with  the  Loicer  Molars.  —  I .  Contrary  to 
what  was  observed  with  regard  to  the  other  teeth,  the  crowns  of  the  lower  great  molars 
are  a  little  larger  than  those  of  the  upper.  2.  They  are  slightly  bent  inward,  while  those 
of  the  upper  great  molars  are  quite  vertical.  3.  The  lower  great  molars  have  only  two 
roots,  an  anterior  and  a  posterior.  These  roots  are  very  strong  and  broad,  flattened  from 
before  backward,  deeply  grooved  longitudinally,  and  bifurcated  at  the  points.  The  upper 
great  molars  have  at  least  three  roots  {figs.  91  and  92),  one  internal  and  two  external. 
It  is  very  easy,  then,  to  distinguish  between  the  molar  teeth  of  the  two  jaws. 

Individual  Characters  of  the  Great  Molars. — 1 .  The  first  great  molar  is  distinguished 
from  the  other  two  by  its  size,  in  which  it  generally  exceeds  them.  2.  The  third  great 
molar,  or  wisdom  tooth,  is  distinguished  from  the  first  and  second  by  its  evidently 
smaller  size  ;  by  its  crown  having  only  three  tubercles,  two  external  and  one  internal ; 
by  its  shortness  ;  and  by  its  roots  being,  in  certain  cases,  more  or  less  completely  joined 
together.  However,  even  where  the  roots  of  these  teeth  are  united,  we  always  find  the 
trace  of  the  characters  proper  to  the  series  of  molar  teeth  to  which  they  belong  ;  i.  e., 
the  vestige  of  three  roots,  an  internal  and  two  external  for  the  upper  wisdom  teeth,  and 
of  two  roots,  an  interior  and  a  posterior  for  the  lower. 

No  teeth  present  so  many  varieties  as  the  last  molares,  which  occasionally  even  remain 
buried  in  the  substance  of  the  maxillary  tuberosity. 

Structure  of  the  Teeth. 

The  crown  of  each  tooth  contains  a  cavity  {d,  figs.  93,  94)  corre^onding  with  it  m 
shape.    This  cavity  is  prolonged  with  contracted  dimensions  into  ^^    gg  y.    g^_ 

the  centre  of  the  root,  and  opens  by  an  orifice  of  variable  size  at  w-     • 

the  apex  of  the  simple  or  compound  cone,  represented  by  the  fang. 
The  dimensions  of  this  cavity  are  in  an  inverse  proportion  to  the 
age  of  the  tooth ;  so  that  it  is  largest  at  the  earliest  periods,  but 
during  the  progress  of  years  it  becomes  entirely  obliterated.  It 
contains  a  soft  substance  constituting  the  dental  pulp.  A  tooth,  i;|| 
therefore,  is  composed  of  two  substances,  an  external  hard  or  c<w- 
ftcai  porhoTi,  which  is  unorganized,*  and  an  internal  organized  pulp. 

The  dental  pulp,  contained  in  tfte  cavity  of  the  tooth  as  in  a 
mould,  has  the  same  form  as  the  tooth  to  which  it  belongs.  This 
pulp  is  cormected  with  the  dental  vessels  and  nerves  by  means  of 
a  nervous  and  vascular  pedicle,  which,  after  penetrating  the  dental  cavity  through  the 
orifice  in  the  apex  of  the  root,  and  traversing  the  small  canal,  becomes  continuous  with 
it.  From  analogies,  the  accuracy  of  which  will  be  seen  in  studying  the  development  of 
the  teeth,  the  pulp  may  be  regarded  as  a  bulb  or  large  papilla,  and  appears  to  consist  of 
a  nervous  expansion  traversed  by  a  great  number  of  vessels.  Its  arteries  are  derived 
from  the  internal  maxillary ;  the  nerves  belong  to  the  superior  and  inferior  maxillary 
branches  of  the  fifth  pair.  A  membrane,  rather  difficult  of  demonstration  on  account  of 
its  tenuity,  envelops  the  pulp,  which  is  extremely  sensitive,  is  the  seat  of  toothache, 
and  to  it  alone  must  be  referred  all  that  has  been  said  regarding  the  vitality  and  sensi- 
bility of  the  teeth. 

The  hard  or  cortical  portion  is  composed  of  two  substances,  one  of  which  covers  th«> 

*  Sfie  note,  p.  183. 


|S2  ODONTOLOGY. 

crown,  and  has  been  called  the  enamel  (e,  figs.  93  and  94),  from  a  comparison  with  the 
vitreous  layer  or  glaze  of  porcelain  ;  the  other,  constituting  the  entire  root  and  the  in- 
terior of  the  crown,  is  the  ivory  (/),  improperly  designated  the  bony  •portion  of  the  tooth. 
The  enamel  is  thickest  on  the  grinding  surface  of  the  tooth  ;  it  diminishes  in  thickness 
as  it  approaches  the  neck,  at  which  part  it  terminates  abruptly.  The  prominence  of  the 
curved  line,  indicating  the  termination  of  the  enamel,  gives  rise  to  the  constriction  call- 
ed the  neck. 

By  comparing,  and,  in  some  degree,  contrasting  the  peculiar  characters  of  the  enamel 
and  the  ivory,  we  shall  be  better  able  to  assign  to  each  their  respective  properties. 

1.  The  enamel  is  of  a  bluish- white,  milky  colour,  and  semi-transparent ;  the  ivory  is 
yellowish-white,  and  has  an  appearance  like  satin. 

2.  The  enamel,  examined  in  fragments  of  the  crown,  exhibits  fibres  perpendicularly 
implanted  upon  the  ivory,  and  pressed  closely  to  each  other.  The  ivory,  on  the  contra- 
ry, is  formed  of  concentric  layers,*  the  fibres  of  which  are  generally  parallel  to  the  long 
diameter  of  the  tooth. 

3.  Both  substances  are  excessively  hard  ;  but  in  this  respect  the  enamel  is  superior 
to  the  ivory,  for  it  will  strike  fire  with  steel,  and  is  much  less  easily  worn  down  by  use ; 
it  can  even  turn  the  edge  of  a  file.  This  excessive  hardness,  a  principal  element  of  im- 
mutability, explains  how  the  teeth  are  preserved  uninjured  as  long  as  the  enamel  re- 
mains entire,  and,  on  the  other  hand,  the  facility  with  which  they  decay  when  once  it 
has  been  removed.  The  great  brittleness  of  the  enamel,  which  is  one  of  its  most  char- 
acteristic properties,  is  also  owing  to  this  extreme  hardness. 

4.  In  chemical  composition,  the  enamel  and  ivory  present  important  diflferences,  indi- 
cated in  the  following  tables  : 


Ivory. 

Enamel. 

Phosphate  of  lime         ... 

61-95 

Phosphate  of  lime         ... 

85-3 

Fluate  of  lime       .... 

210 

Fluate  of  lime       .... 

3-2 

Carbonate  of  lime          ... 

5.30 

Carbonate  of  lime 

8-0 

Phosphate  of  magnesia          -        - 

1-25 

Phosphate  of  magnesia 

1-5 

Soda  and  chloride  of  sodium 

1-40 

Membranes,  soda  and  water 

2-0 

Cartilage  and  water      ... 

28-00 

It  follows,  therefore,  that  the  principal  chemical  distinction  between  these  substances 
depends  on  the  existence  of  cartilage,  that  is,  of  an  animal  matter  in  the  ivory,  and  on 
its  absence  in  the  enamel.  The  presence  of  cartilage  in  ivory  forms  a  trace  of  resem- 
blance between  this  substance  and  bone  ;  and  this  is  farther  strengthened  by  the  result 
of  the  action  of  heat,  by  which  both  are  similarly  aifected.  Between  the  true  bones  and 
the  ivory  there  is,  however,  all  that  diflference  by  which  a  living  tissue  is  distinguished 
from  a  solidified  product  of  secretion.  I  admit,  then,  a  complete  want  of  vitality  both  in 
the  ivory  and  the  enamel  of  the  tooth  ;  nevertheless,  there  are  some  phenomena  which 
appear  to  contradict  such  an  opinion. 

1.  The  cortical  substance  of  the  tooth  affords  a  much  more  perfect  sensation  of  such 
bodies  as  come  in  contact  with  it  than  either  the  nails  or  hair. 

3.  Weak  acids,  particularly  vegetable  acids,  cause  a  peculiar  sensation  when  they  are 
applied  to  the  teeth,  rendering  the  shghtest  touch  extremely  painful ;  a  sensation  gener- 
ally expressed  by  saying  that  the  teeth  are  set  on  edge. 

But  if,  on  the  other  hand,  we  reflect  that  the  substance  of  the  teeth  is  never  affected 
by  inflammation,  that  it  never  becomes  the  seat  of  any  tumour  or  diseased  product,  and 
that  it  is  worn  away  by  rubbing  and  by  the  file,  in  the  same  way  as  an  inorganic  body, 
without  any  attempt  at  reparation  or  any  evidence  of  the  existence  of  a  nutritive  pro- 
cess, we  must  be  led  to  admit  the  absence  of  vitality  in  these  organs,  and  to  explain  the 
foregoing  facts  as  dependant  simply  upon  transmission. 

Lastly,  the  hardness,  fragility,  and  mutability  of  the  enamel  and  ivoiy  vary  in  differ- 
ent individuals  ;  hence  the  difference  in  the  durability  of  the  teeth,  and  their  liability  to 
change.  It  must  not  be  imagined  that  the  ivory,  when  exposed,  is  susceptible  of  caries 
or  necrosis  ;  its  changes  are  entirely  of  a  chemical  nature.  The  contrary  opinion  pre- 
vailed only  so  long  as  the  teeth  were  considered  true  bones,  and  yet  it  has  exercised  an 
influence  over  the  language  of  surgery  which  is  not  yet  removed  ;  thus,  we  are  in  the 
habit  of  speaking  of  a  carious  or  necrosed  tooth,  and  to  describe  them  as  affected  with 
exostosis,  and  even  with  spina  ventosa. 

It  follows,  from  all  that  has  been  said,  that  the  human  teeth  are  simple,  i.  e.,  formed 
by  one  centre  of  ivory  covered  with  one  layer  of  enamel.  Compound  teeth  exist  only  in 
herbivora,  in  which  animals  mastication  consists  of  a  most  extensive  grinding  move- 
ment ;  nor  are  they  met  with  except  among  the  molar  teeth.  The  characteristic  feature 
of  a  compound  tooth  is  the  division  of  the  crown  into  a  greater  or  smaller  number  of 
lesser  crowns,  each  of  which  consists  of  a  centre  of  ivory  covered  by  a  layer  of  enamel. 
All  these  crowns  are  united  into  one  by  a  third  substance,  called  the  cement  or  crusta  pe- 
trosa,  of  which  the  tartar  of  the  human  teeth  will  afford  a  sufficiently  good  idea.t 

*  See  not«,  infra. 

t  tRecent  researches  into  the  structure  of  the  teeth  have  brought  so  many  interesting  facts  to  light,  that  It 
la  necessary  to  notice  the  result  of  these  discoveries. 


DEVELOPMENT    OF    THE    TEETH. 


183 


Development  of  the  Teeth,  or  Odontogeny. 

The  study  of  the  development  of  the  teeth  is  one  of  the  most  interesting  parts  ol 
their  history.  It  embraces  the  description  of  the  phenomena  that  precede,  accompany, 
and  follow  the  eruption  of  the  first  and  second  sets  of  teeth. 

First,  Temporary,  or  Provisional  Teeth. 

Phenomena  which  precede  their  Eruption* — If  the  jaws  of  a  foetus  of  two  or  three 
months  be  examined,  it  will  be  seen  that  they  are  marked  by  a  broad  and  deep  groove, 
divided  by  very  thin  septa  into  so  many  distinct  sockets  for  the  reception  of  the  dental 
germs.  The  alveolar  groove  is  closed  at  its  free  border  by  the  membrane  of  the  gum, 
which  is  stretched  over  a  sort  of  thin,  and,  as  it  were,  indented  crest.  This  crest  is 
formed  by  a  tissue  to  which  some  anatomists  have  given  the  name  of  dental  cartilage  ; 
it  is  a  pale,  very  strong  fibrous  tissue,  and  does  not  extend  either  upon  the  anterior  or 
posterior  surface  of  the  bone,  which  are  only  covered  by  the  mucous  membrane,  the  gum 
being  as  yet  confined  to  the  alveolar  border.  The  gingivjd  fibrous  tissue  sends  a  pro- 
longation into  each  alveolus  (alveola-dental  periosteum),  that  forms  a  fibro-mucous  sac  upon 

Three  different  structures  at  least  enter  into  the  formation  of  the  human  teeth,  viz.,  the  ivory,  the  enamel, 
and  the  cortical  substance. 

The  ivory  {a.  Jig.  95)  consists  of  a  hard,  transparent  substance,  traversed  by  numerous  tubes,  about  -r^-^th 
of  a  hne  in  diameter,  which  commence  by  open  orifices  at  the  cavity  of  the  pulp,  and  extend  in  an  undulating, 
but  nearly  parallel  direction,  towards  the  surface  of  the  ivory.     In  this  course  the  tubes  fig.  95. 

present  secondary  and  smaller  undulations,  undergo  a  dichotomous  division,  diminish  in 
size,  at  first  gradually,  then  rapidly,  give  off  numerous  lateral  twigs,  and,  finally,  divide 
into  extremely  minute  ramifications,  of  which  some  anastomose  together,  others  commu- 
nicate with  small  irregular  dilatations  called  calcigerous  cells,  situated  in  the  transparent 
inter-tubular  substance,  while  the  remainder  appear  to  be  lost  at  or  near  the  surface  of  the 
ivory.  The  cells  and  tubes  both  contain  calcareous  matter,  and  seem  to  be  analogous  to 
the  corpuscles  of  bone  and  the  ramified  lines  radiating  from  them.  In  human  teeth  the 
cells  are  very  minute  ;  but  in  those  of  many  animals  they  are  much  more  distinct,  and 
present  a  striking  analogfy  to  the  osseous  corpuscles. 

The  hard  inter-tubular  substance  is  not  homogeneous,  but,  as  may  be  clearly  seen  in 
young  and  growing  teeth,  is  comjxjsed  of  fibres  arranged  parallel  to  the  tubes,  which  ap- 
pear to  have  distinct  parietes.  It  consists  of  animal  tissue,  combined  with  a  large 
amount  of  calcareous  salts ;  and  it  is  the  scat  of  by  far  the  greater  proportion  of  the 
earthy  matter  contained  in  tlie  ivory  of  the  tooth. 

The  enamel  {b,fig.  95)  is  composed  of  hexagonal  and  transversely  striated  fibres,  about 
x^th  of  aline  in  diameter,  arranged  parallel  to  each  other,  and  applied  by  their  internal 
extremities  to  numerous  corresponding  depressions  on  the  surface  of  the  ivory,  a  delicate 
intervening  membrane  serving  to  connect  the  two  structures.  Near  the  neck  of  the 
tooth,  the  enamel  fibres  rest  almost  perpendicularly,  near  the  apex  of  the  cro\vn,  more 
or  less  obliquely  upon  the  surface  of  the  ivory  ;  moreover,  they  are  often  slightly  waved 
or  curved.  Previously  to  the  eruption  of  the  tooth,  each  fibre  contains  an  appreciable 
quantity  of  organic  matter,  which,  at  later  periods,  almost  entirely  disappears. 

The  cortical  substance  (c,fig.  95)  consists  of  a  thin  osseous  layer  developed  on  the  ex- 
ternal surface  of  the  fangs,  and,  as  life  advances,  extending  even  into  their  interior,  and 
encroaching  upon  the  cavity  of  the  pulp.  It  differs  in  no  essential  particular  from  true 
bone,  containing  the  characteristic  corpuscles,  and  anastomosing  tubuli  of  that  tissue. 
It  has  been  found,  also,  on  the  fangs  of  the  teeth  of  most  mammalia,  and  of  a  few  reptiles 
and  fishes  ;  in  some  instances,  direct  communications  have  been  discovered  between  the  tubes  of  the  ivory 
and  the  cells  and  tubuli  of  the  cortical  substance.  The  cement,  or  crusta  petrosa,  existing  on  the  crowns  of 
the  compound  teeth  of  the  lower  animals,  also  contains  corpuscles  and  tubuli  like  those  of  bone,  and  may,  per- 
haps, be  regarded  as  an  analogous  deposite  to  the  preceding,  differing  from  it  only  in  situation. 

From  a  perusal  of  the  preceding  summary,  it  will  be  seen  that  not  only  has  much  additional  knowledge 
been  acquired  regarding  the  structure  of  the  teeth,  but  that  many  of  the  statements  of  M.  Cruveilhier  must 
now  undergo  considerable  modification.  Thus,  1.  The  crusta  petrosa  bears  no  resemblance  to  the  tartar  of  the 
teeth,  which  is  merely  a  deposite  from  the  saliva.  2.  Even  simple  teeth  contain  a  third  element  in  their  struc- 
ture, besides  the  ivory  and  enamel.  3.  Instead  of  being  inorganic  Iwdies,  the  teeth  are  possessed  of  a  complex 
organization,  which,  we  may  add,  is  uniform  throughout  each  species,  and  often  sufficiently  characteristic  to 
be  of  the  highest  utility  to  the  zoologist,  &c.  4.  A  remarkable  affinity  has  been  established  between  the 
teeth  and  bone,  as  far  as  regards  the  structure  of  the  cortical  substance  and  the  ivory.] 

*  [The  earliest  stage  in  the  development  of  the  teeth,  described  in  the  text,  is  that  in  which  the  dental  pulps 
are  situated  at  the  bottom  of  closed  sacs  ;  it  has  long  been  familiar  to  anatomists,  and  is  now  called  the  saccu- 
lar stage.  A.  condition  antecedent  to  this,  in  which  the  future  sacs  are  as  yet  open  follicles,  was  first  described 
by  Arnold,  but  we  are  indebted  to  Mr.  Goodsir  (Edin.  Med.  and  Surg.  Journ.,  No.  cxxxviii.)  for  the  following 
connected  history  of  the  origin  of  the  pulps  and  sacs  of  the  temporary  and  permanent  teeth  : 

Origin  of  the  Pulps  and  Sacs  of  the  Temporary  Teeth. — In  the  upper  jaw  of  a  foetus,  about  the  sixth  week, 
between  the  lip  and  a  semicircular  lobe  constituting  the  early  condition  of  the  palate,  is  situated  a  denression  of 
the  form  of  a  horseshoe.  During  the  seventh  week,  this  begins  to  be  divided  by  a  ridge  (commencing  from 
behind)  into  two  grooves,  of  which  the  outer  forms  the  recess  between  the  lip  andithe  future  external  alveolar 
process,  while  the  inner  constitutes  the  primitive  dental  groove.  The  mucous  membrane  along  the  floor  of  this 
groove  is  then  thickened,  and  from  it  a  single  papiUa  is  developed,  and  subsequently  four  others  arise  from  the 
external  lip  of  the  groove,  in  either  half  of  the  jaw.  In  the  mean  time,  membranous  laminie  projecting  from  the 
external  lip,  and  at  first  only  partially  surrounding  the  papills,  unite  with  similar  but  smaller  processes  from 
the  internal  lip,  so  that  each  papilla  (p,  3,  Jig.  97)  becomes  enclosed  in  a  separate  follicle  {/,  S,Jig.  97),  com 
municating  with  the  cavity  of  the  mouth,  and  lined  by  its  mucous  membrane.  The  papilla  now  increase  in 
size,  and  gradually  assuming  the  form  of  the  future  temporary  teeih,  sink  within  the  yet  open  follicles.  At 
this  period,  the  edges  of  the  latter  appear  to  be  developed  into  opercula  (0,  4,  Jig-  97),  which  differ  in  number 
and  arrangement  according  to  the  shape  of  the  crowns  of  the  different  teeth,  there  being  two  for  the  incisors, 
three  lur  the  canine,  and  four  or  five  for  the  molars.  The  formation  of  the  bony  alveoli,  by  the  development 
of  an  external  and  internal  alveolar  process,  and  of  inter-alveolar  septa,  closely  follows  the  jireceding  changes 
in  the  soft  parts. 

The  order  and  time  of  appearance  of  these  ten  papil';K  in  the  upper  jaw  are  as  follow  :  F  rst,  those  of  the 


184 


ODONTOLOGY. 


each  follicle,  perforated  at  the  bottom  of  the  socket  for  the  passage  of  the  dental  vessels 
and  nerves.     As  these  prolongations  or  sacs  are  intimately  connected  to  the  gingival 


{Fig.  96,  magnified  three  diameters.) 


anterior  temporary  molars  during  the  seventh  week ;  of  the 
canine  teeth  at  the  eighth ;  of  the  central,  and  then  of  the  lat- 
eral incisors,  about  the  ninth  ;  and  in  the  tenth  week  those  of 
the  posterior  molars.  The  formation  of  the  inter- follicular  sep- 
ta, and  the  other  changes  in  the  papillae,  follicles,  and  alveolar 
borders  described  above,  proceed  in  the  same  order,  and  are 
completed  about  the  thirteenth  week.  The  condition  of  the 
tipper  jaw  at  that  period,  constituting  the  end  of  the  follicular 
stage  in  the  development  of  the  temporary  teeth,  is  seen  in 
Jig.  96,  in  which  the  follicles  are  shown  as  if  held  open  ;  the 
diagrams  1  to  5  in_^g'.  97,  representing  perpendicular  sections 
across  the  jaw,  may  serve  to  illustrate  the  successive  changes 
in  the  mucous  membrane,  from  the  commencement  of  the 
groove  to  the  completion  of  the  follicles. 

During  the  fourteenth  week,  a  small  crescentic  depression 
(c,  5,  Jig.  97)  is  formed  immediately  behind  each  of  the  folli- 
cles, the  mouths  of  which  are  now  closed  by  their  opercula, 
but  without  adhesion ;  the  lips  of  the  groove,  -which  at  this  time  is  called  the  secondary  dental  groove,  are  now 
applied  to  each  other  (6,  fig.  97).  With  the  exception  of  the  ten  depressions  just  mentioned,  and  a  small  por- 
tion situated  beyond  the  posterior  temporary  molar  follicle,  adhesion  of  every  part  of  the  groove  now  takes 
place,  proceeding  from  before  backward.  The  follicles  are  thus  converted  by  the  fifteenth  week  into  shut 
sacs  is,  T,fig.  97),  while  the  enlarged  papilla  constitute  the  dental  pulps  (p,  7).  The  relation  of  the  parts  in 
this,  the  saccular,  stage  in  the  development  of  the  temporary  teeth,  is  represented  at  7,  fig.  97. 

Independently  of  a  few  subordinate  differences,  the  changes  in  the  lower  jaw  are  similar,  and  occur  in  the 
same  order,  each  step  in  the  process  being  somewhat  later  than  the  corresponding  one  in  the  upper. 

Origin  of  the  Pulps  and  Sacs  of  the  Permanent  Teeth.— It  has  been  stated  above,  that  during  the  general 
adhesion  of  the  dental  groove  occurring  at  the  fifteenth  week,  the  part  posterior  to  the  second  temporary  molar 
follicle  (in  either  half  of  the  j-iw)  still  remains  open  ;  in  this  situation,  a  papilla,  sunk  in  an  open  follicle,  ap- 
pears'during  the  sixteenth  week.  At  the  twentieth,  the  fundus  of  this  follicle  is  converted  into  a  sac,  and 
the  papilla  into  the  pulp  of  the  anterior  permanent  molar  tooth,  which  is  thus  the  earhest  to  appear  of  those 
of  the  second  set,  and  is  farther  characterized  by  being  developed  (like  the  papillae  of  the  temporary  teeth) 
from  the  primitive  dental  groove,  and  on  the  same  level  with  them.  At  the  end  of  this  week  the  hitherto  open 
portion  of  the  groove  is  entirely  closed  by  adhesion  of  its  lips,  but  its  walls  still  remain  disunited,  and  a  cavity 
is  thus  formed,  situated  between  the  sac  of  the  anterior  permanent  molar  and  the  surface  of  the  gum  ;  this  is 
the  posterior  cavity  of  reserve,  from  which  the  pulps  and  sacs  of  the  second  and  third  molars  are  subsequently 
developed. 
The  ten  depressions  (c,  6)  formed  behind  the  follicles  of  the  temporary  teeth  during  the  secondary  condi- 


f^W 


i^ 


tion  of  the  dental  groove  (6,  fig.  97),  in  consequence  of  their  escaping  the  general  adhesion  of  its  lips  and  sides, 
Fig.  98.  Fig.  98.* 


are  converted  into  as  laany  c#rities,  called  the  anterior  cav- 
ities of  reserve  (c,  7),  whfch  gradually  elongate  and  recede 
into  the  substance  of  the  gum.  Pulps  and  folds  (analogous 
to  the  opercula  of  the  temporary  follicles)  are  developed 
within  them,  appearing  first  in  the  anterior  cavities  ;  and 
they  eventually  become  the  sacs  of  the  ten  anterior  perma- 
nent teeth,  assuming  a  position  behind  and  above  those  of 
the  miUc  teeth  in  the  upper,  and  behind  and  below  them  in  the  lower  jaw  (see?  to  \%fig-  97  ;  aXso  fig.  98,  and 
a,  figs.  101,  102),  each  occupying  corresponding  recesses  {a,  fig-  102)  in  the  alveolar  border. 

At  this  time,  owing  to  the  great  relative  increase  in  the  size  of  the  dental  sans,  that  of  the  anterior  perma- 
nent molar  (a,  i,fig-  98*)  is  forced  backward  and  upward  into  the  maxillary  tuberosity  of  the  upper,  and  intc 
the  coronoid  process  of  the  lower  jaw  (a  2) ;  and  the  large  posterior  cavity  of  reserve  (6  2)  is  drawn  in  the  same 
direction.  At  birth,  the  length  of  the  alveolar  border  increases  relatively,  and  this  sac  again  sinks  to  a  level 
with  those  of  the  temporary  teeth  (o  3).     The  cavity  of  reserve  (6  3),  having  now  resumed  its  former  poaitioc 


DEVELOPMENT  OP  THE  TEETH.  185 

membrane,  by  pulling  gently  upon  the  latter  we  can  raise  the  follicles  from  their  recep- 
tacles, and  completely  lay  bare  the  alveoli. 

The  follicle  or  dental  germ  consists  essentially  of  a  membraiie,  containing  a  sort  of  pe- 
diculated  papilla,  known  as  the  bulb  or  dental  pulp. 

1.  The  membrane  of  the  follicle,  after  having  clothed  the  sac  just  described  as  lining  the 
alveolus,  is  reflected  upon  the  vessels  and  nerves  which  form  the  pedicle  of  the  bulb,  and 
appears  to  be  prolonged  upon  the  bulb  itself :  this,  however,  has  not  yet  been  demon- 
strated. The  membrane  of  the  follicle,  therefore,  resembles  the  serous  membranes  in 
forming  a  shut  sac,  the  inner  surface  of  which  is  free  and  smooth,  and  the  outer  adhe- 
rent. A  transparent  viscid  fluid  occupies  the  space  between  the  bulb  and  the  alveolar 
portion  of  the  membrane. 

The  following  is  the  order  in  which  the  follicles  of  the  first  set  of  teeth  appear.  To- 
wards the  middle  of  the  third  month  of  foetal  life  there  are  four  distinct  follicles  in  each 
jaw ;  at  the  end  of  the  third  month  a  third  follicle  appears  in  each  h£ilf  of  the  jaw,  and 
a  fourth  and  a  fifth  towards  the  end  of  the  fourth  month. 

2.  Of  the  dental  bulb.  In  the  earliest  stages  the  membrane  of  the  dental  follicle  only 
contains  a  fluid,  which  is  at  first  reddish,  and  afterward  yellowish-white  ;  but  towards  the 
third  month  a  small  body  makes  its  appearance,  rising  as  a  papilla  from  the  bottom  of 
the  alveolus.*  This  papilla  is  abundantly  suppUed  with  vessels  and  nerves,  and  pro- 
gressively increases  in  firmness  and  in  size.  A  very  thin  pedicle,  consisting  of  the  den- 
tal vessels  and  nerves,  affords  attachment  to  it,  so  that  it  is  suspended  like  a  grape. 
This  papilla,  dental  bulb,  or  pulp,  gradually  acquires  the  characteristic  form  of  some  par- 
ticular tooth,  of  which  it  presents  an  exact  model,  constituting  the  nucleus  around  which 
the  tooth  itself  is  deposited.  The  first  part  developed  upon  this  papilla  is  the  crown  of 
the  tooth,  on  which  we  already  find  indications  of  the  various  eminences  and  depressions 
subsequently  exhibited  by  it. 

The  development  of  the  hard  portion  commences  towards  the  middle  of  pregnancy. 
The  production  of  the  ossiform  matter  upon  the  surface  of  the  bulb  is  eflfected  by  a  pro- 
cess of  secretion  ;+  it  begins  by  the  deposition  of  some  small  laminae,  or  very  delicate 
scales  {I,  Jig.  99),  upon  each  projection  of  the  pulp :  they  are  at  first  pUable  and  elastic, 
but  gradually  become  more  consistent.  These  laminae  or  scales  constitute  so  many 
formative  points  for  the  tooth,  and  have  been  compared  to  the  points  of  ossification  in 
bones.  The  incisor  and  canine  teeth  have  only  one  scale  ;  the  bicuspides  have  two, 
and  the  great  molares  as  many  as  there  are  tubercles.  These  small  scales  so  intimate- 
ly embrace  the  pulp  upon  which  they  are  moulded,  that  it  requires  some  force  to  detach 
them  ;  and  yet  their  inner  surface,  as  well  as  the  outer,  is  very  smooth.  It  should  be 
remarked,  that  the  pulp  has  a  much  more  vividly  red  colour  at  the  points  covered  by  the 
scales.     The  scales  are  visible  in  the  lower  jaw  at  an  earlier  period  than  in  the  upper. 

The  following  is  the  order  in  which  they  appear :  the  middle  incisors  are  visible  from 
the  fourth  to  the  fifth  month ;  they  are  soon  followed,  1 .  By  the  lateral  incisors.  2.  By 
the  first  or  anterior  molar,  which  appears  from  the  fifth  to  the  sixth  month.     3.  At  a  short 

and  shape,  elongates  backward,  and  a  pulp  is  developed  in  its  fundus,  -whicli  is  converted  before  the  fourth 
year  into  the  sac  of  the  second  permanent  molar.  About  the  sixth  or  seventh  year,  the  remaining  part  of  the 
cavity  once  more  elongates  backward,  and  forms  the  pulp  and  sac  of  the  third  permanent  molar,  or  wisdom 
tooth.  Each  of  these  sacs  undergoes  changes  in  its  relative  position  in  the  jaws,  similar  to  those  experienced 
by  the  anterior  permanent  molar,  at  first  receding  backward  and  upward,  and  then  descending  behind,  and  on 
a  level  with  the  sac  immediately  anterior  to  it. 

From  the  preceding  observations,  it  follows  that  the  palps  and  sacs  of  both  the  temporary  and  permanent 
teeth  have  a  common  origin  from  the  gastro-intestinal  mucous  membrane  ;  that  a  papilla  is  first  formed,  after- 
ward surrounded  by  and  sunk  into  a  follicle,  which  latter  is  then  converted  into  a  closed  sac  ;  and  hence  the 
origin  of  the  terms  papillary  follicular,  and  saccular,  applied  to  these  several  conditions. 

It  moreover  appears  that  all  the  temporary  teeth,  and  also  the  anterior  permanent  molar,  originate  from  the 
primitive  dental  groove  ;  and  that  all  the  permanent  teeth,  except  the  anterior  molar,  are  developed  from  cav- 
ities of  resen-e  commenced  during  its  secondary  condition. 

For  an  account  of  the  changes  occurring  in  the  pulps  aud  sacs  of  the  two  sets  of  teeth  during  the  saccular 
and  eruptive  stages,  the  reader  may  now  refer  to  the  text,  remembering,  however,  that  the  term  follicle  is  there 
applied  to  the  entire  dental  germ  in  its  saccular  condition,  consisting  of  a  closed  sac  and  its  contained  pulp.] 

*  [The  papilla  of  a  temporary  tooth  appears  even  before  the  formation  of  the  open  follicle,  and  therefore 
long  prior  to  its  conversion  into  a  shut  sac.     (See  note,  p.  183.)] 

t  [The  ivory  is  no  longer  regarded,  by  the  best  authorities,  as  a  secretion  from  the  surface  of  the  dental 
pulp,  nor  the  enamel  as  a  similar  product  from  the  parietal  layer  of  the  lining  membrane  of  the  sac.  A  micro- 
scopic examination  of  these  two  structures  in  their  perfect  condition  is,  indeed,  alone  sufficient  to  throw  con- 
siderable doubt  on  the  old  opinion  adopted  in  the  text.  The  researches  of  Schwann  into  their  mode  of  devel- 
op-oient  have  again  elucidated  the  subject.  It  has  been  observed  that  the  globules  in  the  centre  of  the  dental 
pulp  are  primitive  nucleated  cells,  analogous  to  those  found  in  the  early  condition  of  all  organic  tissues  ;  that 
at  the  surface  of  the  pulp  these  cells  assuro«  a  cylindrical  form  and  a  perpendicular  arrangement,  but  still  con- 
tain nuclei  ;  that  they  adhere  in  places  to  the  ossified  scales,  and  correspond  in  size  (not  to  the  tubuli)  but,  to 
the  fibres  of  the  inter-tubular  substance  in  a  growing  tooth.  From  these  facts  Schwann  concludes  that  th« 
formation  of  the  ivory,  likethat  of  all  other  organized  tissues,  is  effected  by  a  metamorphosis  of  primitive  nu 
cleated  cells ;  in  other  words,  that  it  is  developed  by  a  progressive  transformation  and  ossification  of  the  superfi- 
cial cells  of  the  dental  pulp — a  theory  which  recent  observations  in  Great  Britain  would  seem  to  have  confirmed. 

Similar  evidence  is  advanced  by  him  to  prove  that  the  enamel  is  formed  in  a  similar  manner  from  the  pulp^y 
enamel  membrane,  occupying  the  upper  portion  of  the  sac.  The  hexagonal  fibres,  of  which  the  surface  of  this 
membrane  consists,  are,  in  fact,  prismatic,  nucleated  cells,  resting  perpendicularly  on  a  tissue,  in  which  are 
other  cells  of  a  vesicular  form.  The  hexagonal  fibres  correspond,  therefore,  both  in  form  and  direction,  with 
those  of  the  perfect  enamel ;  and,  moreover,  they  are  found  to  agree  in  size  with  the  membranous  remains  of 
the  enamel  fibres  of  a  growing  tooth,  after  the  removal  of  their  earthy  matter  by  means  of  a  dilute  acid.] 

Aa 


186 


ODONTOLOGY. 


interval  from  each  other,  by  the  canine  and  the  second  molar :  the  scales  of  all  the  teeth 
of  the  first  set  have  made  their  appearance  by  the  seventh  month,  according  to  the  ob- 
servations of  Meckel ;  but  at  the  eighth  month,  according  to  Blake. 

As  development  advances  the  scales  enlarge,  and  gradually  uniting  (2,  fig.  99),  form  a 
sheath  or  shell  of  ivory,  which,  during  its  growth,  encloses  the  pulp,  and,  by  degrees,  ex- 
tends to  the  vascular  and  nervous  pedicle  at  the  part  where  it  penetrates  the  alveolus.* 
The  outermost  sheath  being  formed,  a  second  is  deposited  within  it,  then  a  third  within 
that,  and  so  on.  The  external  surface  of  the  bulb  secretes  the  ivory.  The  enamel  is 
formed  from  the  parietal  or  alveolar  layer  of  the  follicular  membrane  :  at  the  commence- 
ment of  its  formation  it  is  so  soft  that,  in  a  foetus  at  the  full  time,  it  can  be  very  easily 
separated  from  the  ivory.  It  has  been  asserted  by  some  that  the  enamel,  as  well  as  the 
ivory,  is  the  product  of  a  secretion  from  the  bulb,  from  which  it  has  transuded  in  a  liquid 
state  through  the  different  layers  of  the  ivory,  and  has  then  solidified  upon  its  surface ; 
others  affirm  that  the  enamel  is  a  sort  of  crystalline  deposite  from  the  fluid  surrounding 
the  tooth ;  but  the  greater  number  of  anatomists  admit,  with  Hunter,  that  the  enamel  is 
a  product  of  secretion  from  the  parietal  layer,!  as  the  ivory  is  from  the  layer  of  the  fol- 
licular membrane,  reflected  upon  the  bulb.  This  opinion  appears  to  me  the  more  proba- 
ble, because,  on  examining  with  attention  the  parietal  layer,  we  find  on  its  inner  sur- 
face, near  the  crown  of  the  tooth,  a  sort  of  pulp,  or  very  evident  enlargement,  particular- 
ly in  the  follicles  of  the  molar  teeth.  This  external  pulp  becomes  atrophied  as  soon  as 
the  enamel  is  formed ;  and  hence  the  fang  is  not  covered  with  enamel,  although,  after 
the  eruption  of  the  tooth,  that  part  occupies  the  former  position  of  the  crown.  This  ex- 
ternal pulp  does  not  exist  in  some  of  the  dental  follicles  of  certain  animals,  and  we  can- 
not, therefore,  be  astonished  that  such  teeth  have  no  enamel.  Lastly,  when  this  ex- 
ternal pulp  remains  after  the  eruption  of  the  teeth,  the  secretion  of  the  enamel  also  con- 
tinues, like  that  of  the  ivory.  This  is  the  case  with  the  incisors  of  the  rabbit  and  the 
beaver.  In  these  animals  the  enamel  occupies  only  the  anterior  surface  of  the  tooth  ; 
consequently,  the  edge  alw&ys  remains  sharp,  from  the  unequal  wearing  of  the  anterior 
and  posterior  surfaces. 

From  what  has  been  said  concerning  the  phenomena  of  the  formation  of  the  pro  vision- 
ary teeth  before  their  eruption,  we  may  draw  the  following  conclusions  :  1 .  Of  the  two 
constituent  parts  of  a  tooth,  viz.,  the  corticle  or  hard  portion,  and  the  medullary  portion 
or  pulp,  the  latter  is  first  developed  ;  and  of  the  two  distinct  elements  of  the  hard  por- 
tion, viz.,  the  ivory  and  the  enamel,  the  formation  of  the  ivory  is  first  commenced.  2. 
The  deposition  of  the  cortical  substance  of  the  tooth  begins  at  the  crown  ;  the  roots  are 
not  formed  until  a  subsequent  period.  3.  The  bulb  being  enclosed  within  the  solidified 
products  which  it  has  furnished,  diminishes  gradually  in  size  as  these  press  upon  it. 

Phenomena  which  accompany  the  Eru-ption  of  the  First  or  Temporary  Teeth. — At  the  time 
of  birth  all  the  teeth  are  still  contained  within  their  alveoli.  Exceptions  to  this  rule 
have  been  met  with  in  cases  where  infants  have  been  born  with  one  or  two  teeth.  If 
the  anterior  wall  of  the  alveoli  be  removed  at  this  time,  the  teeth  will  already  be  found 
considerably,  but  unequally  developed,  none  having  yet  reached  the  bottom  of  the  socket. 
But  after  birth,  and  at  periods  to  be  presently  indicated,  the  extremity  of  the  root  having 
reached  the  bottom  of  the  alveolus,  and  the  farther  growth  of  the  tooth  in  that  direction 
being  impossible,  it  is  effected  in  the  direction  of  the  gum,  which  is  compressed,  becomes 
inflamed,  and  is  perforated ;  this  perforation,  however,  is  not  exclusively  the  result  of 
distension,  for  the  gum  is  but  very  slightly  stretched  when  it  opens  ;  and  in  other  cases 
where  it  is  greatly  distended,  as  by  polypi  or  other  tumours,  it  is  not  lacerated  at  all. 

The  tooth  gradually  rises,  and  the  gum  moulds  itself  successively  upon  the  different 
portions  of  the  crown,  and,  lastly,  upon  the  neck  of  the  tooth.  The  division  of  the  gum 
is  a  severe  process,  but  still  it  cannot  altogether  explain  those  serious  symptoms  which 
frequently  accompany  the  first  dentition. 

The  eruption  of  the  teeth  does  not  take  place  simultaneously,  but  in  succession,  and 
in  a  regular  order  that  admits  of  but  few  exceptions.  1.  The  teeth  of  the  same  kind  ap- 
pear in  pairs,  one  on  the  right  side,  the  other  on  the  left  ;  2.  The  teeth  of  the  lower  jaw 

*  [The  vascular  pulp  of  either  a  temporary  or  permanent  tooth  having  more  than  one  fang  is,  after  tho 
formation  of  the  crown,  divided  into  as  many  processes  by  the  advancement  into  it  of  the  gray  membrane  of 
the  sac.  The  dental  substance  still  continuing  to  be  produced  on  every  part  of  the  surface  of  the  divided  pulp., 
abridge  of  ivory  is  thus  formed  across  the  area  of  the  cavity  of  the  tooth  between  each  process  (3,  4,jf^.  99), 

(Ft^.  99.) 


around  which  separate  fangs  are  subsequently  developed  (5,  6, 7),  in  the  same  mannpr  ns  that  around  the  niK 
divided  pulp  of  an  incisor  tooth.]  ■•   See  note,  p.  184. 


DEVELOPMENT    OF   THE    'JEETH. 


precede  those  of  the  upper  in  their  appearance  ;*  3.  The  middle  incisors  are  cut  before 
the  lateral,  these  before  the  first  molars  ;  after  these  come  the  canine,  and  then  the  sec- 
ond molars.  The  eruption  of  the  first  set  of  teeth  commences  towards  the  sixth  month 
after  birth,  and  terminates  at  the  end  of  the  third  or  the  commencement  of  the  fourth 
year.  The  middle  lower  incisors  appear  from  the  fourth  to  the  tenth  month,  and,  soon 
afterward,  the  upper  middle  incisors  ;  the  inferior  lateral  incisors  appear  from  the  eighth 
to  the  sixteenth  month,  and  then  the  superior  lateral  incisors.  The  first  lower  molars 
are  cut  from  the  fifteenth  to  the  twenty-fourth  month  ;  the  lower  canine  from  the  twen- 
tieth to  the  thirtieth ;  and  the  upper  first  molars  and  canine  soon  afterward.  In  some 
cases  the  eruption  of  the  canine  and  the  first  molar  teeth  takes  place  simultaneously ; 
sometimes  even  the  canine  teeth  take  the  precedence.  The  second  great  molars  appear 
from  the  twenty-eighth  to  the  fortieth  month,  and  thus  complete  the  twenty  teeth  of  the 
first  set. 

Second  or  Permanent  Teeth. 

Phenomena  which  precede  the  Eruption.i — The  second  dentition  consists  of  the  eruption 
of  the  teeth  called  permanent,  to  distinguish  them  from  the  temporary  teeth.  They  are 
thirty-two  in  number,  so  that  there  are  twelve  additional  teeth  in  the  second  set.  In 
this  dentition,  as  in  the  former,  we  have  to  study  the  phenomena  which  precede,  ac- 
company, and  follow  the  eruption  of  the  teeth. 

The  follicles  or  germs  of  the  second  set  of  teeth  correspond  to  the  row  of  teeth  already 
formed,  bony  septa  intervening  between  them.  They  have  the  following  relations  with 
the  follicles  of  the  provisionary  teeth  :  1.  The  follicles  of  the  additional  teeth  in  the  sec- 
ond set,  viz.,  the  last  three  molars,  are  situated  in  the  same  curve  as  the  milk  teeth,  but 
they  occupy,  of  necessity,  the  lateral  extremities  of  these  curves  {Jig.  100).  2.  The  fol- 
licles of  those  teeth  of  the  second  set  that  replace  others  of  the  first  are,  on  the  contrary, 
situated  precisely  behind  the  teeth  to  which  they  correspond  {a,  Jigs.  100,  101,  102). 

These  follicles  are  at  first  contained  in  the  same  alveoli  as  the  temporary  teeth  ;  but. 
after  a  certain  time,  septa  are  grad-  Fig.  lOO. 

ually  formed  between  them,  pro-  _.^— -—f 

ceeding  from  the  bottom  of  each 
alveolus  towards  its  orifice  (Jigs. 
101, 102).  Nevertheless,  for  a  long 
time  after  the  formation  of  these 
septa,  the  temporary  (a""  a",  Jig.  102) 
and  the  permanent  ("b  ^b)  alveoli 
communicate  by  tolerably  large  or- 
ifices (c'  c',Jigs.  101,  102),  through 
which  proceed  the  cords  (c.  Jig. 
102)  connecting  the  two  teeth.  The 
follicles  of  the  permanent  teeth  do  not  sensibly  difier  in  their  mode  of  development  from 
those  of  the  provisionary  teeth,  only  the  increase  of  the  vascular  system  of  the  former 
coincides  with  the  progressive  atrophy  of  the  vessels  of  the  latter. 

Phenomena  which  accompany  their  Eruption. — As  long  as  the  development  of  the  per- 
manent teeth  can  be  efiected  in  a  direction  towards  the  bottom  of  their  sockets,  the  tem- 
porary teeth  remain  uninjured  ;  but  when  the  growth  of  the  permanent  teeth  influences 
their  upper  edges,  the  alveoli  of  the  first  set  are  compressed,  and  afterward  destroyed  at 
the  parts  corresponding  to  the  crowns  of  the  permanent  teeth  Fig.  101. 

(see^^.  101).  After  this  time  the  alveoli  of  the  first  and  sec- 
ond sets  form  common  cavities :  the  roots  of  the  milk  teeth 
being  compressed  by  the  crown  of  the  permanent  teeth,  under- 
go a  loss  of  substance,  become  loosened,  and  may  be  detached 
by  the  slightest  effort,  each  tooth  being  retained  in  its  place 
only  by  the  sort  of  ring  formed  by  the  gum  around  its  neck. 

The  shedding  of  the  milk  teeth  is  not  always  effected  in  the 
way  we  have  described,  viz.,  by  a  previous  destruction  of  their 
root.  Sometimes,  in  fact,  the  permanent  tooth  does  not  pen- 
etrate into  the  alveolus  of  the  corresponding  milk  tooth ;  but 
this  alveolus  is  gradually  wasted  away  by  the  constantly  in- 
creasing development  of  the  neighbouring  permanent  socket, 
teeth  may  fall  without  destruction  of  their  roots,  which,  however,  are  then  almost  always 
slender,  and,  as  it  were,  atrophied.  Some  compression,  either  exercised  upon  the  pa- 
rieties  of  the  temporary  sockets,  or  upon  the  roots  of  the  milk  teeth,  is  almost  indispen- 
sable for  their  expulsion.  When,  in  fact,  the  permanent  tooth  deviates  from  its  natural 
direfction,  and,  consequently,  does  not  press  upon  the  milk  tooth,  this  latter  remains,  and 
forms  a  supernumerary  tooth.  We  cannot,  then,  doubt  the  influence  of  this  compression 
upon  the  fall  of  the  milk  teeth ;  but  anatomists  are  not  agreed  as  to  the  immediate  cause 
of  the  destruction  of  the  temporary  alveoli,  and  of  the  roots  of  the  teeth  contained  within 

*  [Although  the  papillae,  it  wiU  be  rememliered,  appear  earlier  in  the  upper  jaw.]  t  See  note,  p.  183, 


In  this  case,  the  milk 


188 


ODONTOLOGY. 


them.  How  does  this  compression  act  1  Does  it  produce  the  fall  of  the  milk  teeth  in  a 
purely  mechanical  manner,  or  does  it  effect  this  indirectly  by  the  destruction  of  the  den- 
tal vessels  and  nerves  1  One  author  believes  the  latter  to  be  the  principal  cause  ;  but 
what  we  have  already  said  regarding  the  want  of  vitality  in  the  teeth  will  abundantly 
prove  that  the  wearing  away  of  the  alveolus  and  the  milk  tooth  is  the  result  of  mechan- 
ical pressure. 

At  the  same  time  it  should  be  observed,  that,  since  the  destruction  of  the  roots  of  the 
milk  teeth  leaves  no  debris,  a  process  of  absorption  must,  therefore,  be  performed,  the  ex- 
citing cause  of  which  is,  undoubtedly,  the  compression  above  alluded  to.  It  is  not  neces- 
sary, as  some  authors  have  believed,  to  assume  the  existence  of  a  peculiar  absorbent  ap- 
paratus, appropriated  to  this  office. 
The  teeth  of  the  first  dentition  are  shed  in  the  space  comprised  between  the  sixth  and 
j^  JQ2  the  eighth  year,  the  fall  of  each  tooth 

taking  place  in  the  same  order  as  its  ap- 
Kr'i^N  '  ^1^  /\  pearance.     Blake  was  the  first  to  point 

out  the  existence  of  a  cord  (c.  Jig.  102) 
passing  from  the  follicle  of  the  perma- 
nent tooth,  along  a  small,  long  canal  (c' 
c'),  behind  the  alveolus  of  the  milk  tooth, 
and  becoming  continuous  with  the  gum. 
It  has  been  supposed  that  the  canal,  and 
the  cord  placed  within  it,  were  intended 
to  direct  the  tooth  during  the  progress 
of  its  eruption.  Hence  the  name  of  iter 
dentis  given  to  the  canal,  and  guhernac- 
ulum  dentis  applied  to  the  cord,  which 
has  been  ingeniously  compared  by  M. 
Serres  to  the  gubernaculum  testis.  This 
cord  appears  to  me  to  be  solid,*  not  hollow ;  it  is  very  well  marked  in  the  incisor  teeth, 
but  forms  a  mere  thread  in  the  molars.  Upon  the  whole,  the  influence  exerted  by  the 
iter  dentis  and  gubernaculum  upon  the  direction  of  the  permanent  teeth  during  its  erup- 
tion is  by  no  means  constant. 

Order  of  Eruption. — The  first  permanent  teeth  which  appear  are  the  first  great  molars ; 
they  precede  the  other  permanent  teeth  by  a  considerable  interval,  and  immediately  suc- 
ceed the  milk  teeth,  coexisting  with  them  for  some  time  ;  they  have  been,  therefore,  im- 
properly classed  among  the  first  set  of  teeth  in  some  anatomical  treatises.  The  first 
great  molars  are  known  by  the  vulgar  name  of  seven  years'  teeth.  The  eruption  of  the 
permanent  teeth  takes  place  in  the  same  order  as  that  of  the  milk  teeth.  Below  are  sta- 
ted the  periods  at  which  each  pair  are  protruded  : 

Middle  lower  incisors from 

Middle  upper  incisors  ....  .        .  " 

Lateral  incisors  .        •. " 

First  small  molar " 

Canine  teeth " 

Second  small  molar " 

Second  great  molar " 

Third  great  molar " 

The  greatest  irregularity  exists  in  the  eruption  of  this  last  molar  tooth,  which  is  often 
wanting,  and  frequently  remains,  during  the  whole  of  life,  either  partially  or  entirely  en- 
closed within  the  substance  of  the  jaw. 

The  incisor  and  canine  teeth  of  the  second  set  are  much  larger  than  the  corresponding 
milk  teeth.  The  opposite  is  the  case  with  regard  to  the  first  two  permanent  molars,  viz., 
the  small  molars,  or  bicuspides.  It  was  ascertained  by  the  inquiries  of  Hunter,  that,  in 
this  way,  there  is  such  a  compensation,  that  the  twenty  teeth  of  the  first  set  occupy  pre- 
cisely the  same  space  as  the  twenty  corresponding  teeth  of  the  second.  This  is  not  a 
purely  speculative  question,  but  one  of  singular  interest  in  relation  to  the  practice  of  ex- 
tracting the  milk  teeth.  The  truth  of  Hunter's  assertion  may  be  confirmed  by  measuring 
with  a  thread  the  space  occupied  by  the  twenty  temporary  teeth,  and  comparing  it  with 
the  space  occupied  by  the  corresponding  teeth  of  the  second  set.  M.  Delabarre  has 
done  this  upon  the  same  individual  at  the  period  of  the  two  dentitions. 

Plienomena  which  follow  the  Eruption  of  the  Permanent  Teeth. — These  relate,  1.  To  their 
growth ;  2.  To  their  decadence. 

1.  Growth  of  the  Teeth. — ^The  teeth  of  man  are  not,  like  those  of  some  animals,  the  ro- 
dentia  in  particular,  susceptible  of  unlimited  growth.  The  enamel  of  the  crown  wears 
away  without  ever  being  reproduced.  All  the  facts  brought  forward  in  support  of  the  idea 
of  its  reproduction  are  either  erroneous  observations,  or  may  be  interpreted  in  a  different 
manner.  Nevertheless,  some  changes  take  place  in  the  interior  of  the  tooth  which  are 
worthy  of  notice.  New  layers  of  ivory  continue  to  be  secreted;  &nO  the  cavity  of  the 
*  [Arising  from  the  adhesion  of  the  sides  of  the  elongated  part  of  the  cavity  of  resene.l 


6  to 

8  years 

7  " 

9 

8  " 

10 

9  " 

11 

10  " 

12 

11  " 

13 

12  " 

14 

28  " 

30 

DEVELOPMENT  OF  THE  TEETH.  199 

tooth  is  gradually  encroached  upon,  and  finally  obliterated.    Thus  the  teeth  of  the  aged 
have  neither  pulp  nor  dental  cavity. 

2.  Decadence  of  the  Teeth. — The  fall  of  the  teeth  in  aged  persons  is  the  effect  of  a  con- 
traction of  the  alveoli,  produced  in  the  following  manner  :  The  teeth  are  dependances  of 
the  buccal  mucous  membrane,  and  are,  as  it  were,  only  accidentally  placed  in  the  alveo- 
lar borders,  which,  from  the  tonicity  or  elasticity  of  their  bony  tissue,  have  a  constant  ten- 
dency to  displace  them.  In  one  word,  the  tooth  is  to  the  alveolus  like  a  foreign  body,  of 
which  it  is  incessantly  tending  to  free  itself  This  tendency  to  contract  on  the  part  of 
the  alveolus  is  effectually  resisted,  so  long  as  the  root  of  the  tooth  has  a  tendency  to  in- 
crease towards  the  bottom  of  the  socket ;  but  it  acts  with  full  force  when  this  resistance 
ceases  in  consequence  of  atrophy  of  the  pulp.  Then  the  alveolus,  shrinking  upon  it- 
self, expels  the  tooth  by  a  mechanism  similar  to  that  by  which,  during  the  progress  of 
syphilitic  affections,  the  most  healthy-looking  teeth  are  displaced,  solely  in  consequence 
of  the  vitality  of  the  pulp  being  destroyed  by  the  influence  of  the  virus. 

The  fall  of  the  teeth  in  the  aged  is  regulated  by  no  law,  either  as  regards  the  time  or 
the  order  in  which  it  is  effected. 

Differences  between  the  First  and  Second  Sets  of  Teeth. — The  teeth  of  the  first  dentition 
are  distinguished  from  those  of  the  second  by  the  following  characters  :  1 .  Their  colour, 
instead  of  being  white,  like  ivory,  or  clear  yellow,  is  of  a  bluish  or  azure  white  hue.  2. 
The  temporary  incisor  and  canine  teeth  are  always  distinguished  from  the  corresponding 
permanent  teeth  by  their  smaller  size  and  the  shortness  of  their  roots.  3.  The  two  mo- 
lars of  the  first  set  differ  from  the  two  small  permanent  molars  or  bicuspids  which  take 
their  place,  and  approach  nearer  in  character  to  the  great  molars  ;  from  these,  however, 
they  are  distinguished,  by  the  shortness  of  their  crowns,  and  by  the  number  of  tubercles 
on  them,  viz.,  five  ;  three  on  the  outside,  and  two  on  the  inside.  4.  Comparative  chem- 
ical analyses  of  the  teeth  of  the  two  sets  have  shown  that  the  milk  teeth  contain  some- 
what less  phosphate  of  lime  than  the  permanent,  and  to  this  circumstance  their  greater 
susceptibility  of  change  is  due. 

General  Observations. — From  the  description  we  have  given  of  the  teeth,  it  will  be  seen 
that  these  organs  should  be  looked  upon  merely  as  large  vascular  and  nervous  papillae, 
covered  by  an  unorganized  calcareous  sheath,  which  is  formed  by  a  species  of  crystalli- 
zation.* The  diseases  of  the  teeth  offer  nothing  incompatible  with  this  theory,  for,  with 
the  exception  of  toothache,  and  the  sensation  of  being  set  on  edge,  which  are  evidently 
seated  in  the  pulp,  the  other  alterations  of  which  the  teeth  are  susceptible  are  either  me- 
chanical lesions,  such  as  splitting,  cracking,  wearing,  &c.,  or  chemical  changes,  as  the 
dry  or  moist  caries,  or,  lastly,  alterations  appearing  to  have  their  seat  in  the  hard  sub- 
stance of  the  tooth,  but  which  are  really  situated  elsewhere.  Of  this  nature  are  the  in- 
crustations with  tartar,  the  product  of  a  vitiated  secretion,  attributed  by  several  anato- 
mists, and  especially  by  M.  Serres,  to  some  small  follicles,  the  function  of  which,  before 
the  eruption  of  the  teeth,  is  to  produce  a  fluid  to  soften  the  gum  preparatory  to  its  perfo- 
ration by  the  teeth.  Again,  exostosis  and  spina  ventosa  of  the  teeth  evidently  depend 
upon  irregular  secretion  of  the  enamel  and  ivory.  The  consolidation  of  fractures  of  the 
teeth  is  explained  by  the  formation  of  new  layers,  resembling  those  which  have  been 
seen  surrounding  bullets  in  the  substance  of  an  elephant's  tusk.  Lastly,  the  coloration 
of  the  teeth,  from  the  action  of  madder,  is  only  observed  in  the  layers  deposited  during 
its  use,  and  therefore  does  not  prove  the  existence  of  any  nutritive  process  in  these  or- 
gans, such  as  takes  place  in  bone. 

With  regard  to  the  evolution  of  the  teeth  in  two  distinct  sets,  it  may  be  inquired  what 
is  the  object  of  such  an  arrangement.  Without  entering  here  into  the  discussion  of  final 
causes,  it  cannot  be  denied  that  the  second  set  of  teeth  would  not  accord  with  the  com- 
paratively small  size  of  the  jaws  in  the  foetus. 

Use. — 1.  The  teeth  are  the  immediate  agents  of  mastication.  The  incisors  cut,  the 
canine  tear,  and  the  molars  grind  the  food,  the  position  of  each  being  regulated  by  the 
resistance  they  have  to  overcome.  2.  The  teeth  form  a  kind  of  elevated  border,  which 
prevents  the  constant  escape  of  saliva  from  the  mouth.  3.  They  assist  in  rendering 
sounds  articulate,  by  affording  a  fixed  point  to  the  tongue  in  the  pronunciation  of  certain 
consonants,  called  by  grammarians  dental.  4.  The  teeth  furnish  important  characters 
for  zoological  classifications.  Indeed,  as  they  bear  a  necessary  relation  to  the  mode  of 
feeding  in  different  animals,  a  circumstance  that  exercises  so  great  an  influence  over 
their  entire  organization,  it  may  easily  be  conceived  that  the  fonn  of  the  teeth  is,  to  a 
certain  extent,  one  of  the  characters  by  which  a  summary  idea  is  conveyed  of  the  nature 
of  that  organization.  At  the  same  time,  it  is  necessary  to  guard  against  the  evidently 
erroneous  conclusions  which  some  philosophers  have  delighted  in  deducing  from  the  ar- 
rangement of  the  dental  apparatus  in  man  with  regard  to  his  fitness  for  a  purely  animal 
or  exclusively  vegetable  diet.  Above  all,  it  should  be  remembered  that  the  mechanical 
mgenuity  of  mankind  must  always  form  an  indispensable  element  in  the  solution  of  every 
problem  of  this  nature. 

*  [It  is  necessary,  in  some  degree,  to  modify  this  definition  of  the  hard  portion  of  the  teeth,  which,  though 
extra-vascular,  and,  on  that  account,  probably  subject  neither  to  interstitial  absorption  nor  nutrition,  cannot 
be  regarded  with  propriety  as  unorganized  or  crystalline  bodies. 


190  MYOLOGY. 


MYOLOGY. 

The  Muscles  in  general. — Nomenclature. — Number. — Volume  and  Substance. — Figure. — Di- 
rection.— Relations. — Attachments. — Structure. — Uses. — Preparation. — Order  of  Descrip- 
tion. 

The  active  organs  of  locomotion  are  called  muscles.*  They  are  composed  of  bundles 
of  red  or  reddish  fibres,  consisting  of  fibrin  as  their  basis,  and  possessing  the  essential 
property  of  contractility,  that  is,  the  power  of  contracting  or  shortening  upon  the  applica- 
tion of  a  stimulus,  t 

JVomenclature  of  Muscles 

The  names  applied  to  the  various  muscles  have  not  been  founded  upon  uniform  prin- 
ciple. Before  the  time  of  Sylvius  the  muscles  of  any  region  (of  the  thigh,  for  example) 
were  designated  numerically,  first,  second,  &c.,  in  the  order  of  their  super-position  or  of 
their  uses.  Sylvius  first  gave  particular  names  to  the  greater  number  of  the  muscles ; 
and  he  was  followed  by  almost  all  succeeding  anatomists,  especially  by  Riolanus.  In 
this  nomenclature,  which  is  still  generally  adopted,  the  names  of  the  muscles  are  deri- 
ved, 1.  From  their  situation,  as  radialis,  ulnaris,  peroneus,  &c.  ;  2.  From  their  size,  as 
glutaeus  maximus,  minimus ;  palmaris  longus,  brevis,  &c. ;  3.  From  their  direction,  £is 
rectus  abdominis,  obliqui  capitis ;  4.  From  their  shape,  which  is  generally  an  imperfect 
representation,  either  of  certain  geometric  figures,  as  rhomboideus,  pyramidalis,  and  sca- 
lenus, or  of  well-known  objects,  as  deltoideus,  lumbrici,  and  soleus  (from  solca,  the  sole 
fish) ;  5.  From  their  divisions  or  complications,  as  digastricus  (from  having  two  bellies), 
triceps  (from  having  three  heads),  biceps,  complexus,  &c. ;  6.  From  their  insertions,  as 
stemo-hyoid,  stemo-thyroid,  &c. ;  7.  From  their  uses,  as  flexors,  abductors,  &c. 

In  modem  times  many  attempts  have  been  made  to  substitute  in  the  place  of  these 
vague  and  generally  arbitrary  denominations,  a  uniform  nomenclature,  derived  from  the 
most  important  consideration,  viz.,  the  attachment  of  the  muscles.  The  nomenclature 
of  Chaussier,  however,  which  is  undoubtedly  superior  to  all  others,  has  not  been  adopt- 
ed ;  first,  because  a  knowledge  of  the  old  names  cannot  be  neglected,  since  they  are  the 
only  ones  employed  in  a  great  number  of  works  on  medicine  and  surgery  ;  and,  second- 
ly, because  even  the  most  imperfect  denominations,  when  they  have  been  long  in  use, 
are,  from  this  circumstance  edone,  preferable  to  any  new  appellations. 

JVumber  of  the  Muscles. 
Upon  this  point,  likewise,  authors  are  but  little  agreed.  According  to  most,  the  num- 
ber of  muscles  is  four  hundred.  Chaussier  reduced  it  to  three  hundred.  These  differ- 
ences arise  partly  from  the  fact  that  the  natural  limits  of  the  different  muscles  are  not 
so  well  marked  as  those  of  the  bones,  for  example,  and  partly  because  the  grounds  of  de- 
marcation between  the  various  muscles  have  not  been  sufficiently  established.  The  fol- 
lowing rules  may  be  adopted  with  advantage  :  1.  When  a  number  of  fasciculi  unite,  and 
form  a  mass,  which  is  isolated  both  in  its  body  and  at  its  extremities,  and  fulfils  distinct 
and  determinate  uses,  such  a  collection  should  be  considered  a  separate  muscle.  2.  A 
muscle  should  also  be  regarded  as  distinct  when  it  is  separated  from  others  at  one  por- 
tion only  of  its  body,  and  at  the  most  movable  of  its  attachments.  On  the  whole,  what- 
ever be  the  mode  of  demarcation  adopted,  it  will  be  seen  that  the  number  of  the  muscles 
greatly  exceeds  that  of  the  bones ;  the  reason  of  this  is,  that  each  bone  acts  as  a  lever 
in  a  great  variety  of  movements,  while  each  muscle  acts  only  in  a  very  limited  number 
of  motions. 

Volume  and  Substance  of  the  Muscular  System. 

Of  all  the  systems  of  organs  in  the  body,  the  muscular  is  predominant  both  in  substance 
and  in  volume.  This  great  mass  of  muscular  apparatus  is  a  necessary  consequence  of 
the  unfavourable  position  of  most  of  the  levers  represented  by  the  bones.  There  is  very 
great  variety  in  different  individuals,  as  regards  both  the  volume  and  substance  of  the 
muscular  system.  Compare,  in  this  respect,  the  glutaeus  maximus  of  a  robust  man,  and 
the  same  muscle  in  a  thin,  nervous  individual,  much  emaciated,  but  yet  in  perfect  health, 
for  still  greater  differences  are  produced  by  disease  :  size  and  strength  of  the  muscular 
system  may  also  be  natural  or  acquired,  partial  or  general.  Partial  preponderance  is 
most  usuEdly  acquired,  and  is  commonly  the  result  of  exercise.  To  be  convinced  of  this, 
it  is  only  necessary  to  inspect  the  muscles  of  certain  regions,  in  individuals  whose  em- 
ployment requires  the  special  exercise  of  those  parts.  The  preponderance  of  the  mus- 
cles on  the  right  side  is  produced  solely  by  the  habit  of  using  this  side  more  than  the 
other  ;  it  is  not,  as  has  been  alleged,  the  result  of  congenital  difference. 

Lastly,  the  size  of  one  or  the  other  region  of  the  muscular  system,  in  different  anim£ils, 

*  From  nvi)V,  a  muscle,  or  /itij,  a  mouse. 

t  It  will  be  seen  that,  in  constructing  this  definition,  the  only  object  has  been  to  distinguish  the  muscles  gen 
erally  from  other  orgaas,  by  pointing  out  their  two  characteristic  properties,  viz.,  their  fibrinous  comnosition 
■ad  their  contractility. 


FIGURE    AND    DIRECTION   OF    THE   MUSCLES.  191 

is  in  relation  either  with  their  instinctive  propensities,  their  mode  of  feeding,  or  their 
natural  attitude,  or  with  some  other  important  peculiarity  in  their  organization.  Hence 
we  find,  1.  In  the  lion,  the  tiger,  and  other  carnivorous  animals  that  tear  their  prey  in 
pieces,  the  muscles  connected  with  the  inferior  maxiUa,  the  most  highly  developed  ;  2. 
In  the  bear,  which  is  a  climbing  animal,  the  muscles  of  the  back  ;  3.  In  the  hare,  whose 
mode  of  progression  is  by  successive  leaps,  the  muscles  of  the  hind  limbs  ;  4.  The  mus 
cles  of  the  wing  in  birds  ;  and,  5.  Those  of  the  lower  extremities  and  the  vertebral  grooves 
in  man,  to  whom  the  erect  position  is  peculiar 

Figure  of  the  Muscles. 

The  figure  of  the  muscles  is  determined  upon  the  foUoviing  data  :  1.  From  a  compari- 
son of  them  with  geometric  figures  or  with  famihar  objects.  2.  From  the  respective  ar- 
rangement of  their  surfaces,  edges,  and  angles.  3.  From  their  being  symmetrical  or 
otherwise.  In  this  latter  respect  there  is  a  remarkable  difference  between  the  osseous 
and  the  muscular  systems :  many  bones  are  symmetrical,  or  azygos,  while  almost  all  the 
muscles,  on  the  contrary,  are  asymmetrical,  and  arranged  in  pairs.  4.  From  the  relative 
proportion  between  their  three  dimensions ;  from  this  latter  consideration,  muscles  have 
been  divided  into  three  classes,  viz.,  long,  broad,  and  short,  concerning  each  of  which  we 
shall  make  some  general  remarks. 

The  long  muscles  are  chiefly  met  with  in  the  limbs.  Their  length  is  sometimes  con- 
siderable ;  and  the  longest  are  always  most  superficial.  Very  long  muscles  generally 
pass  over  several  articulations,  and  can  therefore  assist  in  moving  them  all.  This  great 
length  of  certain  muscles  has  also  another  advantage,  viz.,  that  it  enables  them  to  obtain 
a  fixed  point  of  attachment  upon  a  less  movable  part,  as  the  trunk,  from  which  they  can 
then  act  upon  the  more  mobile  parts  :  such  is  the  case  with  the  muscles  that  move  the 
thigh  or  the  leg.  Long  muscles  are  either  simple  or  divided.  Sometimes  the  division 
occurs  at  the  more  movable  attachment ;  sometimes  at  that  which  is  habitually  fixed. 

The  broad  muscles  occupy  the  pjirietes  of  cavities  ;  they  are  quadrilateral  when  all  their 
points  of  attachment  are  on  the  trunk,  and  triangular  when  they  extend  from  the  trunk 
to  the  extremities.  When  several  broad  muscles  are  super-imposed,  the  fibres  of  one 
always  cross  those  of  another  at  an  angle  ;  and  this  arrangement,  by  forming  a  sort  of 
interweaving,  greatly  augments  the  strength  of  the  parietes  which  they  assist  in  forming. 
This  is  particularly  well  shown  in  the  broad  muscles  of  the  abdomen. 

The  short  muscles  are  generally  met  with  in  the  same  situations  as  the  short  bones. 
It  is  not  the  shortness  of  its  fibres,  but  of  its  fleshy  body  that  characterizes  a  short  mus- 
cle. It  is  important  to  notice,  with  regard  to  these  muscles,  that  a  number  of  them  are 
often  arranged  in  succession,  so  as  to  resemble  a  long  muscle.  Of  this  we  shall  find 
many  examples  in  the  muscles  of  the  vertebral  grooves. 

Direction  of  the  Muscles. 

The  direction  of  the  muscles  is  one  of  the  most  important  points  in  their  history,  since, 
without  a  knowledge  of  this,  it  is  impossible  to  appreciate  their  uses.  Each  muscle  has 
an  axis  or  middle  line,  in  which  the  general  action  of  its  fibres  takes  effect.  Few  mus- 
cles are  altogether  rectilinear  ;  most  are  angular  or  curved  ;  and  almost  all  undergo  cer- 
tain deviations  or  reflections  in  passing  round  the  joints :  some,  indeed,  take  a  direction 
at  right  angles  to  their  primitive  course,  when  they  pass  over  pulleys  or  hook-like  pro- 
cesses.    In  muscles  of  this  kind  the  action  is  in  the  direction  of  the  reflected  portion. 

The  direction  of  muscles  must  be  studied  with  reference  to  the  axis  of  the  body,  but 
especially  to  the  axis  of  the  limb  or  lever,  in  relation  to  which  they  represent  the  moving 
power.  Many  muscles  are  almost  parallel  to  the  axis  of  the  lever  upon  which  they  act ; 
but  it  should  also  be  remarked  that,  in  certain  positions,  these  same  muscles  form  great- 
er or  smaller  angles  with  their  corresponding  levers,  and  may  even  become  perpendicu- 
lar to  them.  In  this  respect  the  direction  of  the  muscles  is  not  absolute,  but  is  subordi- 
nate to  the  position  of  the  levers. 

Some  muscles  are  constantly  perpendicular  to  the  levers  upon  which  they  act. 

The  angles  of  incidence  of  the  muscles  upon  their  points  of  attachments  are  very  va- 
riable, but  generally  they  are  more  nearly  parallel  than  perpendicular  to  those  points. 
As  the  axis  of  a  muscle  is  not  the  same  as  that  of  its  component  fibres,  it  is  necessary  to 
study,  in  each  muscle,  not  only  the  direction  of  the  fleshy  beUy,  but  that  of  the  fibres  also. 

Relations  or  Connexions  of  the  Muscles. 

In  reference  to  surgery,  the  relations  or  connexions  of  the  muscles  are  among  the 
most  important  circumstances  in  their  history. 

Relations  of  the  Muscles  to  the  Skin. — Those  muscles  only  which  are  called  cutaneous 
are  immediately  connected  with  the  skin  ;  the  remainder  are  separated  from  it  by  apo- 
neuroses of  greater  or  less  density,  so  that  the  skin  does  not  participate  in  the  move- 
ments of  the  m.uscles,  and  vice  versa.  Nevertheless,  the  changes  produced  in  the  form 
and  size  of  the  muscles  during  their  contraction  are  so  decided,  that  those  which  lie 
near  the  surface  are  more  or  less  defined  through  the  integuments  ;  but  the  projections 


192  MYOLOGY. 

corresponding  to  the  bodies  of  the  muscles  and  the  depressions  at  their  attachments 
are,  in  a  measure,  obliterated  by  adipose  tissue,  the  quantity  of  which  varies  in  the  two 
sexes  and  in  different  individuals.  To  this  latter  circumstance  are  due  the  differences 
in  the  outward  characters  of  the  muscular  system  of  the  female,  as  compared  with  the 
male  ;  and  of  a  fat  individual,  as  compared  with  the  one  who  is  emaciated. 

Relations  of  the  Muscles  to  the  Bancs. — In  the  limbs  where  the  muscles  form  several  par- 
allel layers  around  the  bones,  the  belly  or  thickest  part  of  the  muscle  always  corresponds 
with  the  shaft  or  most  slender  portion  of  the  bone  ;  while  the  ends  of  the  muscle,  where 
it  is  thinnest,  correspond  with  the  expanded  extremities  of  the  bone.  The  relations  of 
the  bones  with  the  muscles  vary,  according  as  the  latter  are  deep-seated  or  superficial. 
The  superficial  are  only  in  contact  with  the  bones  by  their  extremities  or  their  tendons 
the  deep-seated  muscles  alone  correspond  to  the  bones  by  their  entire  length. 

Relations  of  the  Muscles  to  each  other. — The  muscles  are  arranged  upon  each  other  in 
successive  layers  ;  each  muscle  is  covered  by  a  sort  of  fibro-cellular  sheath  ;  and  a  loose 
and  moist  cellular  tissue  is  interposed  between  the  different  sheaths,  so  as  to  facilitate 
the  gliding  movement  and  independent  contraction  of  each  muscle.  This  isolation  of 
the  muscles  does  not  exist  throughout  their  entire  length  ;  several  are  often  blended 
together  in  one  conunon  insertion,  from  which  they  proceed  as  from  a  centre,  afterward 
separating  from  each  other.  This  community  of  attachment  is  principally  observed  in 
those  muscles  that  perform  analogous  offices,  or  that,  usually  at  least,  act  simultaneously. 
Most  muscles  are  enclosed  in  a  separate  fibrous  sheath,  which  isolates  them  in  their 
actions,  and  also  in  their  diseases.  Of  this  we  shall  find  remarkable  examples  in  the 
rectus  abdominis  and  sartorius.  With  regard  to  the  relations  of  their  edges,  the  muscles 
are  sometimes  contiguous  throughout  their  entire  course,  and  sometimes  separated  by 
intervals,  generally  of  a  triangular  figure  ;  and  principally  important  in  surgical  anatomy, 
because  incisions,  for  the  exposure  of  vessels,  are  almost  always  made  in  such  intervals. 

Relations  of  Muscles  to  the  Vessels  and  Nerves. — The  muscles  serve  to  protect  the  ves- 
sels and  nerves,  not  only  in  consequence  of  the  thickness  of  the  layers  which  they  form 
in  front  of  them,  but  also  by  the  resistance  they  oppose  during  their  contraction  to  ex- 
ternal violence.  Near  the  centre  of  a  limb  there  is  generally  a  considerable  cellular  in- 
terval between  the  muscular  layers,  which  is  intended  for  the  principal  vessels  and  nerves. 
The  existence  of  such  spaces  prevents  the  injury  which  these  vital  parts  would  sustain 
from  compression  during  the  contraction  of  the  muscles.  It  is  also  worthy  of  notice, 
that  whenever  a  vessel  passes  through  the  body  of  a  muscle,  we  find  an  aponeurotic  arch 
or  ring,  which  is  non-contractile,  and  in  some  degree,  therefore,  obviates  the  danger  of 
compression  during  the  action  of  the  muscular  fibres.  I  say  in  some  degree,  because, 
in  order  to  render  compression  of  the  vessels  impossible,  the  muscular  fibres  attached  to 
these  rings  must  have  proceeded  from  them  as  from  a  centre,  diverging  in  all  directions. 
In  this  case,  the  action  5f  the  muscles  would  not  change  the  form  of  the  rings,  but  would 
tend  to  increase  their  diameters  in  every  direction.  It  is  found,  however,  that  they  are 
invariably  elongated  in  one  direction  and  diminished  in  another,  when  the  fibres  of  the 
muscle  contract.  Bernouilli,  indeed,  has  shown  that  it  is  impossible  to  change  the  form 
of  a  circle,  by  making  one  of  its  diameters  greater  than  the  others,  without,  at  the  same 
time,  diminishing  its  capacity ;  because,  within  a  given  periphery,  the  most  regular  fig- 
ures have  the  greatest  capacity,  and  the  circle  is  more  regular  than  either  the  oval  or 
the  ellipse.  On  the  whole,  however,  it  must  be  understood  that  the  contraction  of  the 
fibrous  rings  does  not,  in  any  material  degree,  impede  the  circulation. 

It  should  also  be  remarked,  that  a  distinct  fibrous  sheath  surrounds  the  vessels  and 
the  nerves,  serving  to  isolate  and  protect  them  amid  the  various  muscles  by  which  they 
are  surrounded. 

Most  of  the  arteries  have  accompanying  muscles,  which  may  be  called  their  respective 
satellites :  thus,  the  sartorius  is  the  satellite  muscle  of  the  femoral  artery,  the  biceps  of 
the  brachial,  the  stemo-mastoid  of  the  carotid,  &c. 

Attachments  or  Insertions  of  Muscles. 

The  attachments  or  insertions  of  muscles  constitute  one  of  the  most  important  points  in 
their  history,  and  one  which  requires  to  be  studied  with  the  greatest  care,  because  the 
uses  of  a  muscle  can  be  determined  from  a  knowledge  of  its  insertions  alone.  These 
insertions  should  be  considered  in  two  points  of  view  :  1.  As  to  the  direct  insertion  of 
the  muscular  fibres  into  the  tendons,  aponeuroses,  or  other  structures ;  2.  As  to  the  in- 
sertion of  the  tendons  and  aponeuroses  into  the  levers  represented  by  the  osseous  system. 

The  muscular  fibres  themselves  are  attached,  1.  To  the  skin,  of  which  mode  there  are 
numerous  examples  in  the  muscles  of  the  face  ;  2.  To  other  muscular  fibres,  as  in  many 
muscles  of  the  face  and  of  the  tongue  ;  3.  To  cartilages,  as  in  several  of  the  muscles  of 
the  chest  and  larynx  ;  4.  To  aponeuroses,  of  which  they  act  as  tensors,  and  whose  power 
of  resistance  they  thereby  increase;  lastly,  to  tendons  or  aponeuroses,*  that  are  them- 
selves attached  to  the  bones. 

The  fleshy  fibres  are  inserted  into,  or  become  continuous  with,  the  tendons  and  apo- 

*  [The  tendons  afford  examples  of  the  fascicular  form  of  fibrous  tissue,  for  a  notice  of  which  see  note,  tn/jd.) 


ATTACHMENTS  AND  STRUCTURE  OF  MUSCLES.  193 

neuroses  in  the  following  manner :  Tlie  tendon  is  prolonged  under  the  form  of  a  mem- 
brane, either  upon  the  surface  or  in  the  substance  of  the  muscle.  The  results  of  this 
arrangement  are,  1 .  An  increase  of  surface  for  the  attachment  of  the  muscular  fibres, 
which  the  tendon  gathers  up,  as  it  were,  in  order  to  concentrate  their  efforts  upon  one 
point ;  2.  An  obliquity  in  the  insertion  of  the  fibres,  in  reference  to  the  axis  of  the  entire 
muscle,  by  which  the  direction  of  the  power  is  represented.  It  may  easily  be  conceiv- 
ed that  this  obliquity  is  of  the  greatest  interest  as  regards  the  dynamic  relations  or  ac- 
tive property  of  the  muscles.* 

One  of  the  most  curious  circumstances  respecting  the  continuity  of  a  tendon  or  an 
aponeurosis  with  a  muscle  is  the  very  intimate  union  between  the  muscular  and  fibrous 
tissues,  which  is  so  complete  that  they  are  scarcely  ever  separated  by  external  violence, 
which,  moreover,  tends  to  lacerate  the  muscle  rather  than  the  tendinous  fibres. 

It  is  a  fact  worthy  of  notice,  and  one  which  we  have  already  had  frequent  occasion  to 
remark,  that  the  adhesion  of  any  two  organic  tissues  is  stronger  than  the  respective  co- 
hesion of  each ;  so  that  the  tissues  themselves  will  sooner  break  than  admit  of  separa- 
tion from  one  another. 

Insertion  of  the  Aponeuroses  and  Tendons  into  the  Bones. — A  tendon  or  an  aponeurosis 
forms  a  species  of  ligament,  by  means  of  which  the  action  of  a  very  large  muscle  is 
transmitted  to  the  lever  intended  to  be  moved,  by  a  fibrous  cord  or  aponeurotic  lamina 
of  small  size.  A  great  advantage  arises  from  this  mode  of  economizing  the  extent  of 
bony  surface  required  for  muscular  attachments  ;  for,  notwithstanding  the  extent  of 
surface  afforded  by  the  expanded  ends  of  the  bones,  and  by  the  eminences  and  ridges 
with  which  they  are  covered,  it  would  be  evidently  insufficient,  were  the  muscular  fibres 
to  be  directly  attached. 

The  existence  of  tendons  and  aponeuroses  produces  also  this  remarkable  result,  viz., 
that  the  muscular  insertions  are  much  stronger  than  they  would  otherwise  have  been. 
The  aponeurotic  tissue  acts  as  a  transition  structure,  being  in  some  points  of  its  organi- 
zation analogous  to  bone,  and  in  others  approaching  that  of  muscle.  The  analogy  be- 
tween the  bony  and  fibrous  tissues  is  confirmed  by  the  frequent  occurrence  of  ossifica- 
tion in  the  latter,  even  under  normal  conditions,  as  may  be  observed  in  the  formation  of 
the  sesamoid  bones,  and  also  in  the  mode  by  which  tendons  are  attached.  It  has  been 
observed,  in  fact,  that  at  the  point  of  junction  of  the  tendons  with  the  bones  there  is  a 
sort  of  mutual  fusion  of  the  tissues,  from  which  so  intimate  a  connexion  results,  that  the 
proper  substance  of  the  tendons  always  gives  way  before  they  can  be  separated  from  the 
bones,  their  attachments  to  which  even  maceration  will  scarcely  destroy. 

Of  the  different  bones  with  which  a  muscle  is  connected,  some  remain  immovable  du- 
ring its  contraction,  while  others  are  put  in  motion  ;  hence  the  distinction  between  Jixed 
and  movable  attachments.  But  this  eminently  useful  distinction  must  not  be  taken  in  an 
absolute  sense  ;  it  is  only  rigorously  true  of  a  very  small  number  of  muscles,  which,  like 
some  of  those  found  in  the  face,  being  connected  by  one  extremity  with  the  skin,  and 
by  the  other  with  the  bones,  can  give  rise  to  movements  only  at  their  cutaneous  at- 
tachments. In  the  greater  number  of  muscles,  on  the  contrary,  although  one  of  the  at- 
taclunents  is  most  commonly  fixed  and  the  other  movable,  yet  their  relative  condition 
may  be  changed,  and  they  may  become  alternately  fixed  and  movable ;  it  is  therefore 
necessary,  in  explaining  the  action  of  a  muscle,  carefully  to  notice  the  supposed  mobility 
or  fixedness  of  the  different  attachments  at  the  time. 

In  comparing  such  attachments  as  are  habitually  fixed  with  those  that  are  constantly 
movable,  we  shall  observe  that  the  former  are  either  numerous  or  spread  out  by  means 
of  aponeuroses,  whereas  the  latter  consist  of  very  accurately-circumscribed  tendons. 
The  figurative  expressions  of  head  and  tail,  given  to  the  §nds  of  a  muscle,  refer  to  this 
arrangement.  The  fixed  attachment  of  a  muscle  is  usually  blended  with  those  of  several 
others,  while  the  movable  one  is  distinct.!  In  order  to  facilitate  our  description,  we 
shall  invariably  designate  the  fixed  attachment  of  a  muscle,  its  origin,  and  the  movable 
attachment,  its  termination  or  insertion. 

Structure  of  Muscles. 

Muscles  are  composed  of  two  kinds  of  fibres  :  1.  Of  red  or  contractile  fibres,  wYiich  form 
the  muscular  tissue  properly  so  called ;  2.  Of  white,  strong,  and  non-contractile  fibres,  con- 
stituting the  tendons  and  aponeuroses.  In  speaking  of  the  ligaments,  we  mentioned  the 
general  properties  of  tendons  and  aponeuroses  as  belonging  to  the  fibrous  tissues  ;  we 
shall  now  make  a  few  remarks  on  the  peculiar  characters  of  muscular  tissue. 

1.  Colour. — Muscular  tissue  is  of  a  reddish  colour,  the  intensity  of  which  varies  in  dif- 
ferent muscles  and  in  different  individuals.  This  colour  is  not  an  essential  character 
even  in  the  human  subject,  for  the  contractile  fibres  of  the  intestinal  canal  are  very 

*  In  fact,  as  the  tendon,  and  the  aponeuroses  by  which  it  is  continued  into  the  muscle,  represent  the  direc- 
tion of  the  power,  the  fleshy  fibres  must  necessarily  be  attached  to  it  more  or  les.s  obliquely.  It  is  not  our  in- 
tention to  examine  here  the  great  loss  of  power  which  this  arrangement  involves. 

t  [This  assertion  must  be  taken  with  some  limitation.  We  shall  find  many  exceptions  to  this  general  rule, 
(S  we  proceed  in  the  description  of  the  muscles.] 

Bb 


194  MYOLOGY. 

pale  ;*  still  less  is  it  so  in  the  lower  animals,  some  of  which  have  the  entire  muscular 
system  perfectly  colourless.  The  red  colour  of  the  muscular  fibre  is  independent  of  the 
blood  contained  within  the  vessels  of  the  muscle. 

2.  Consistence. — The  consistence  of  the  muscular  fibres  varies  in  different  subjects  . 
in  some  it  is  soft  and  easily  torn ;  in  others  it  is  firmer  and  more  resisting,  and  retains 
for  some  time  after  death  a  degree  of  rigidity  which  yields  with  difficulty  to  forcible  ex- 
tension. 

Structure. — The  muscles  may  be  divided  into  bundles  or  fasciculi  of  different  orders, 
and  these,  again,  into  distinct  fibres,  which  are  visible  to  the  naked  eye,  and  rendered 
more  apparent,  either  by  dissection,  or  by  the  action  of  alcohol,  of  diluted  nitric  acid,  or 
even  of  boiling  water.  They  are  of  a  variable  shape,  resembling  prisms  of  three,  four, 
five,  or  six  surfaces,  but  are  never  cylindrical.  Their  length  also  varies  in  different 
muscles,  in  but  a  few  of  which  do  they  extend  parallel  to  each  other  tliroughout  the  en- 
tire length  of  the  fleshy  belly. 

Each  muscle  is  surrounded  by  a  sheath  of  cellular  tissue,  which  also  penetrates  into 
its  substance,  and  surrounds  both  the  fasciculi  and  fibres.  This  cellular  tissue  permits 
the  free  motion  of  the  different  fasciculi  upon  one  another,  while  it  serves,  at  the  same 
time,  to  isolate  each  and  combine  the  whole.  + 

The  chemical  analysis  of  muscular  tissue  shows  that  it  is  composed  of  a  small  quan- 
tity of  free  lactic  acid  (Berzelius) ;  gelatin ;  some  salts  ;  osmazome  in  greater  or  less 
quantity,  according  to  the  more  or  less  advanced  age  of  the  individual ;  and  leucine,  a 
substance  extracted  from  this  tissue  by  the  process  described  by  M.  Braconnot.  {Ann. 
de  Chim.  et  de  Phys.,  tom.  viii.)t 

In  addition  to  the  tendinous  and  fleshy  fibres,  vessels,  nerves,  and  cellular  tissue  also 
enter  into  the  composition  of  muscles.  We  have  already  described  the  disposition  of 
the  cellular  tissue  contained  in  these  organs ;  the  mode  of  distribution  of  their  vessels  and 
nerves  will  be  more  appropriately  alluded  to  in  the  description  of  the  vascular  and  ner- 
vous systems.^ 

Uses  of  Muscles. 
The  muscles  are  the  active  organs  of  motion,  constituting  the  source  of  the  power 

*  [The  involuntary  muscular  tissue,  of  which  the  above-named  fibres  afford  examples,  are,  v»ith  the  excep- 
tion of  the  heart,  of  a  much  paler  colour  than  the  voluntary  muscles,  to  which  this  division  of  the  present 
work  exclusively  refers.] 

t  [In  reference  to  the  microscopic  structure  of  the  voluntary  muscles,  or  those  of  animal  life,  it  has  been 
ascertained  that  the  smallest  fasciculi  (corresponding  with  the  prismatic  fibres  of  our  author,  and  with  the 
secondary  fasciculi  of  Miiller),  the  size  of  which  varies  in  different  muscles,  are  divisible  into  transversely-slri- 
ated  fibres  (the  primitive  fasciculi  of  Miiller),  having  a  uniform  diameter  in  all  muscles  in  the  same  species, 
and  being  themselves  composed  of  still  smaller  elementary  parts  named _/t?amcn<*  (the  primitive  fibres  of  Miil- 
ler). All  these  elements  of  the  muscular  tissue  extend  parallel  to  each  other,  from  one  tendinous  attachment 
to  another,  never  having  been  seen  to  bifurcate  or  coalesce. 

In  man  the  fibres  vary  from  y^o^th  to  -g-^Tfth  of  an  inch  in  diameter  ;  the  transverse  striae  upon  them  are 
parallel,  generally  straight,  but  occasionally  slightly  waved  or  curved  ;  they  are  situated  at  intervals  of  from 

The  filaments  are  varicose  or  beaded,  i.  e.,  alternately  enlarged  and  contracted  ;  their  diameter  is  from 
_  '  th  to  y-f^^nTr''^  °f  *"  inch.  According  to  the  general  opinion,  they  are  held  together  in  each  fibre  by 
means  of  a  glutinous  substance,  which  latter,  according  to  Skey,  constitutes  the  entire  centre  of  the  fibre,  the 
circumference  alone  being  occupied  by  the  filaments.  In  the  larvae  of  insects,  a  delicate  membranous  sheath, 
sometimes  observed  projecting  beyond  the  filaments,  has  been  described  by  Schwann  as  forming  a  proper  in- 
vestment of  the  fibre  ;  and,  by  analogy,  this  is  also  presumed  to  exist  in  man  and  the  other  vertebrata.  Be  this 
as  it  may,  it  is  certain  that  the  fibres  have  no  separate  sheaths  of  cellular  tissue  derived  from  the  common 
sheath  of  the  muscle,  the  prolongations  of  which  appear  to  extend  only  so  far  as  to  enclose  the  smallest  fasciculi. 
The  cause  of  the  striated  appearance  has,  perhaps,  not  been  quite  satisfactorily  ascertained  ;  but  since  the 
enlargements  on  the  varicose  filaments  are  darker  than  the  constricted  portions,  and  since  they  are  situated 
at  intervals  precisely  similar  to  those  between  the  transverse  strios  of  the  corresponding  fibre,  and  from  some 
other  additional  considerations,  it  has  been  supposed,  with  great  probability,  to  result  from  the  enlarged  and 
dark  portions  of  the  filaments  being  arranged  side  by  side. 

For  an  account  of  the  microscopic  characters  of  the  involuntary  or  organic  muscular  fibres,  see  the  notes  ot 
the  structure  of  the  several  viscera,  &c.,  in  which  they  are  found,  viz.,  the  alimentary  canal,  trachea,  genito- 
urinary organs,  and  iris.    We  may  remark  here,  that  the  muscular  fibres  of  the  heart  and  of  the  upper  part 
of  the  oesophagus  are  striated,  and  approach  very  closely  in  character  to  those  of  animal  life.] 
X  [The  following  analysis  of  the  muscles  of  the  ox  is  on  the  authority  of  Berzelius  ; 

Water 77-17 

Fibrin  (with  vessels  and  nerves) 15.8 

Cellular  tissue  convertible  into  gelatin 1  '9 

Albumen  and  colouring  matter 2'2 

Alcoholic  extract,  or  ozmazome,  with  lactic  acid  and  lactates       1  '8 

Watery  extract,  with  phosphate  of  soda 1'05 

Phosphate  of  lime -08 

100- 
The  inadvertent  omission,  on  the  part  of  M.  Cruveilhier,  oi fibrin  as  one  of  the  proximate  principles  of  mus- 
cle, will  serve  to  impress  on  the  mind  of  the  reader  its  importance  as  a  constituent  of  that  tissue,  in  which  it 
exists  in  greater  abundance  than  in  any  other. 

The  substance  called  leucine,  mentioned  in  the  text,  is  a  product  resulting  from  the  action  of  concentrated 
sulphuric  acid  on  muscular  fibre,  and  therefore  must  not  be  regarded  as  previously  existing  in  it.] 

^  As  it  is  our  intention  to  introduce,  after  Myology,  an  account  of  the  Aponeuroses,  we  shall  be  content  at 
present  with  the  general  ideas  that  have  been  already  stated  regarding  this  important  division  of  the  fibrous 
tissues. 


USES    OF    MUSCLES. 


195 


that  is  applied  to  the  various  levers  represented  by  the  component  parts  of  the  skeleton. 
The  movements  produced  are  the  result  of  that  peculiar  property  possessed  by  the  mus- 
cles of  shortening  themselves,  which  is  called  muscular  contractihiy  {myotiliti).  The 
shortening  of  a  muscle  is  termed  its  contraction,  and  the  opposite  state  its  relaxation. 

Phenomena  of  Muscular  Contraction. — During  contraction  the  muscular  fibres  become 
folded  in  a  zigzag  manner  throughout  their  entire  length ;  the  muscle  itself  becomes 
hardened,  and  broader  and  thicker  in  proportion  to  the  amount  of  shortening.  There  is 
no  oscillation  in  a  muscular  fibre  during  a  normal  contraction.* 

The  aponeuroses  and  the  tendons  take  no  part  in  the  contraction  ;  they  are  entirely 
passive.  The  degree  of  shortening  of  which  the  muscular  fibre  is  susceptible  cannot 
be  precisely  determined ;  as  far  as  we  know,  the  shortening,  and,  consequently,  the  ex- 
tent of  the  resulting  movement,  is  proportional  to  the  length  of  the  fibre.  A  distinction 
should  be  drawn  between  the  force  and  the  velocity  or  rapidity  of  muscular  contraction. 
Again,  the  velocity  is  very  different  from  the  extent  of  motion :  the  latter  depends  upon 
the  length  of  the  fibres  ;  the  former  has  no  connexion  with  it,  but  varies  according  to  the 
constitution  of  the  individual,  and  is  probably  dependant  on  a  more  or  less  rapid  influx 
of  nervous  influence. 

The  muscular  force  is  composed  of  a  great  number  of  elements.  According  to  Borel- 
li,  an  intrinsic  and  an  effective  farce  may  be  distinguished  in  each  muscle.  The  in- 
trinsic force  is  that  power  which  the  muscular  fibres  would  exert  if  they  were  in  the 
most  favourable  position  for  contraction :  the  effective  force  is  measured  by  the  result. 
The  estimation  of  the  force  of  a  muscle  presupposes  a  knowledge,  1 .  Of  the  number  of 
its  fibres.  2.  Of  ther  quality  or  constitution.  3.  Of  the  nature  of  the  lever  upon  which 
it  acts.  4.  Of  the  angle  of  incidence  of  the  muscle  upon  that  lever ;  and,  5.  Of  the  angle 
of  incidence  of  the  fibres  with  respect  to  the  imaginary  axis  of  the  muscle. 

1.  Each  muscular  fibre,  being  distinct  from  those  around  it,  may  be  considered  as  a 
small  power ;  it  may,  therefore,  be  eeisily  conceived  that  the  greater  the  number  of  fibres 
in  any  muscle,  the  more  energetic  will  be  its  contraction. 

2.  The  quality  and  constitution  of  the  fibre,  and  the  intensity  of  the  stimulus,  have  no 
less  an  influence  upon  the  contractile  force  of  a  muscle  than  the  number  of  its  fibres.  To 
be  convinced  of  this,  it  is  sufficient  to  compare  the  energy  of  movement  in  an  individual 
excited  by  anger  with  that  in  one  who  is  C2ilm. 

3.  The  determination  of  the  kind  of  levert  represented  by  the  bone  upon  which  the 
muscle  acts,  is  a  fundeimental  point  in  studying  muscular  action.  It  is  a  law  in  mechan- 
ics, that  the  power  acts  with  greater  effect  in  proportion  as  its  arm  of  the  lever  exceeds 
in  length  that  of  the  resistance.  The  most  common  lever  in  the  human  body  is  that  of 
the  third  order,  in  which  the  power,  being  applied  between  the  fulcrum  and  the  weight, 
is  therefore  most  disadvantageously  situated  for  action. 

4.  As  far  as  regards  energy  of  movement,  the  lever  to  which  the  power  is  applied  is 
as  unfavourable  as  possible,  because  the  muscles  are  generally  inserted  near  the  fulcrum. 

*  The  observations  of  Rogerus  tend  to  show  that  rapid  contractions  and  relaxations  are  cotutantly  takiiig 
place  in  muscles,  especially  during  their  contraction. — (TV.) 

"  Be  Peri)etua  Fibrarum  Muscularium  Palpitatione,"  1760.  Fig.  103. 

t  A  lever,  in  mechanics,  signifies  an  inflexible  rod  capable  of  turning 
round  a  point.  The  point  upon  which  the  lever  turns  is  called  the  /ui- 
crum  if,  figs-  103,  104, 105) ;  the  cause  of  motion  is  called  the  power  (p) ; 
and  the  obstacle  to  be  surmounted  is  the  resistance  (r)  ;  the  space  be- 
tween the  fulcrum  and  the  power  is  the  power-arm  of  the  lever  ;  the  space 
between  the  fulcrum  and  the  weight  is  the  resistance-arm  of  the  lever. 
There  are  three  kinds  of  levers,  distinguished  by  the  respective  arrange- 
ment of  the  three  parts :  1.  A  lever  of  the  first  order  {fig.  103)  has  the  ful- 
crum between  the  power  and  the  resistance.  2.  A  lever  of  the  second  or- 
der (fig.  104)  has  the  resistance  between  the  fulcrum  and  the  power.  3. 
A  lever  of  tlte  third  order  {fig.  105)  has  the  power  between  the  resistance 
and  the  fulcrum 

Fig.lOi. 


196  MiULoGV, 

But,  as  a  sort  of  compensation,  an  advantage  peculiar  to  animal  mechanics,  the  motions 
gain  in  velocity  and  extent  what  they  lose  in  force,  which,  however,  may  still  be  obtain- 
ed by  an  increase  in  the  number  of  muscles,  and  of  the  fleshy  fibres  of  each  muscle. 
Nevertheless,  levers  of  the  most  favourable  construction,  and  of  the  most  advantageous 
position,  are  met  with  in  situations  where  considerable  force  is  required ;  as  in  the  ar- 
ticulation of  the  foot  with  the  leg,  presenting  an  example  of  a  lever  of  the  second  order ;  and 
in  the  articulation  of  the  head  with  the  vertebral  column,  forming  a  lever  of  the  first  order. 

The  angle  of  incidence  most  favourable  to  the  power  is  the  right  angle  ;  but  in  the  hu- 
man body,  as  the  muscles  are  arranged  in  layers  upon  the  bones  which  they  are  intend- 
ed to  move,  they  are  for  the  most  part  inserted  at  very  acute  angles.  Their  incidence 
would  be  still  more  unfavourable  were  it  not  for  the  enlargement  of  the  articular  ex- 
tremities of  the  bones,  which  disturb  the  parallelism  of  the  muscles.  Besides,  in  certain 
cases,  the  angle  of  incidence  more  or  less  approaches,  or  even  attains  to  a  right  angle, 
and  is  combined  with  an  extremely  advantageous  lever,  when  such  an  arrangement  is 
required :  a&  in  the  articulation  of  the  foot  with  the  leg. 

It  is  of  importance  to  notice,  in  determining  the  action  of  a  muscle,  that  its  incidence 
upon  the  bone  varies  at  different  periods  during  its  action ;  so  that  a  muscle  which  is 
eilmost  parallel  to  the  lever  when  it  begins  to  contract,  becomes  perpendicular  to  it  at  a 
given  moment  during  that  process.  It  maybe  said  that  the  momentum  of  a  muscle  occurs 
at  that  period  of  its  action  when  its  perpendicular  incidence  gives  it  the  utmost  energy 
of  which  it  is  capable  :  thus,  the  momentum  of  the  action  of  the  biceps  femoris  takes 
place  when  the  leg  forms  a  right  angle  with  the  thigh.  In  a  certain  number  of  muscles 
the  momentum  coincides  with  the  commencement  of  action,  such  as  the  gastrocnemii 
and  the  solei.  In  some  muscles  the  angle  of  incidence  remains  the  same  throughout  the 
whole  time  of  their  action,  and,  consequently,  they  have  no  momentum :  this  is  the  case 
with  the  deltoid. 

The  angle  of  incidence  of  the  muscular  fibres,  with  regard  to  the  imaginary  axis  of 
the  muscle  or  the  terminating  tendon,  involves  a  loss  of  power  proportional  to  the  amount 
of  the  angle.  In  some  muscles  the  aponeuroses  form  a  continuation  of  the  fleshy  fibres  ; 
in  others,  the  angle  of  incidence  of  the  muscular  fibre  is  so  acute  that  it  may  be  left  out 
of  consideration. 

Estimation  of  the  Action  or  Uses  of  the  Muscles. — Since  the  contraction  of  a  muscle  con- 
sists in  its  shortening,  it  follows  that  its  action  may  be  determined,  a  priori,  from  a 
knowledge  merely  of  its  attachments  and  direction.  It  may  also  be  ascertained  experi- 
mentally, by  placing  a  limb  in  such  a  position  that  the  muscfe  in  question  shall  be  per- 
fectly relaxed.  As  the  same  muscle  generally  performs  several  uses,  it  is  necessary  to 
place  the  limb  in  several  different  positions,  so  as  to  determine  those  in  which  the  mus- 
cle becomes  relaxed.  Let  us  take,  for  example,  the  glutaeus  maximus.  If  we  desire  to 
relax  this  muscle  completely,  it  is  necessary,  1.  To  extend  the  thigh  upon  the  pelvis. 
2.  To  abduct  it.  3.  To  rotate  it  outward  :  hence  it  follows  that  the  glutaeus  maximus 
is  at  once  an  extensor,  an  abductor,  and  a  rotator  outward  of  the  thigh.  As  a  counter- 
proof,  the  limb  must  be  placed  in  such  a  condition  that  the  muscle  becomes  completely 
stretched.  The  successive  positions  in  which  a  muscle  becomes  stretched  will  be  the 
very  reverse  of  those  which  the  limb  assumes  during  the  contraction  of  the  muscle. 
Thus,  the  glutaeus  maximus  is  slightly  stretched  by  rotation  inward,  more  so  by  adduc- 
tion, and  most  completly  by  flexion  of  the  thigh  upon  the  pelvis. 

In  determining  the  action  of  a  muscle  that  is  reflected  over  any  angle  of  a  bone,  it  is 
necessary  to  put  out  of  consideration  all  that  portion  of  the  muscle  intervening  between 
its  origin  and  its  angle  of  reflection,  and  to  suppose  the  power  to  operate  directly  from 
the  latter  points. 

The  action  of  sphincter  muscles  is  to  close  the  orifices  around  which  they  are  placed. 
A  curvilinear  muscle  assumes  a  rectilinear  direction  at  the  very  commencement  of  its 
action. 

The  insertions  of  a  muscle  are  neither  equally  fixed  nor  equally  movable.  The  fixed 
•  point  of  a  muscle  is  that  extremity  which  remains  immovable  during  contraction  ;  but,  in 
certain  cases,  the  fixed  may  become  the  movable  point :  this  must  be  taken  into  consider- 
ation in  determining  the  action  of  a  muscle.  The  fixed  point  is  most  commonly  that 
which  is  nearest  to  the  trunk.  But,  with  few  exceptions,  it  is  never  completely  station- 
ary ;  and  since  a  muscle  would  lose  much  of  its  power  when  acting  between  a  movable 
and  an  imperfectly  fixed  point,  it  is  necessary  that  the  latter  should  be  kept  as  immova- 
ble as  possible  by  the  contraction  of  other  muscles.  These  consecutive  contractions  are 
often  very  extensive,  and  should  be  familiar  both  to  the  physician  and  the  physiologist. 

When  a  muscle  passes  over  several  articulations,  it  moves  them  all  in  succession, 
commencing  with  the  one  nearest  to  the  movable  insertion. 

Those  muscles  which  concur  in  producing  the  same  motion  are  called  congenerous ; 
those  which  execute  opposite  movements  are  termed  antagonists :  thus  all  the  flexor 
muscles  of  any  region  are  congenerous,  and  they  are  antagonists  to  the  extensors. 

Two  muscles  may  be  congenerous  at  one  time,  and  act  as  antagonists  at  another : 
when  they  contract  simultaneously,  their  individual  and  opposite  effects  are  destroyed. 


PREPARATION,  ETC.,  OP    MUSCLES.  197 

and  a  common  and  intermediate  effect  results ;  thus,  when  the  flexor  carpi  ulnaris,  which 
is  both  an  adductor  and  a  flexor,  acts  in  conjunction  with  the  extensor  carpi  ulnaris, 
which  is  an  adductor  and  extensor,  the  hand  is  neither  flexed  nor  extended,  but  is  mere- 
ly adducted.  We  shall  constantly  have  occasion  to  notice  this  arrangement,  which  ap- 
pears to  me  calculated  to  give  much  greater  precision  of  motion  than  if  two  perfectly 
congenerous  muscles  had  been  employed. 

There  are  also  certain  compound  motions,  which  are,  as  it  were,  the  results  of  two 
different  movements ;  thus,  when  the  flexors  and  the  adductors  of  the  thigh  act  simul- 
taneously, the  femur  passes  in  the  intermediate  direction.  It  is  from  this  kind  of  com- 
bination that  the  movement  of  circumduction  is  produced  by  the  action  of  the  four  orders 
of  muscles  situated  at  the  extremities  of  the  antero-posterior  and  transverse  diameters 
of  the  joint.  These  four  orders  of  muscles  are  known  by  the  names  oijlexors,  extensors, 
adductors,  and  abductors. 

Lastly,  muscles  may  contract  without  producing  any  motions,  as  when  antagonist 
muscles  act  with  equal  energy.  The  result  of  such  a  simultaneous  contraction  is  an 
active  immobility  or  tonic  movement,  as  the  older  WTiters  termed  it,  which  is  of  very  great 
importance. 

Preparation  of  Muscles. 

Dissection. — The  end  to  be  attained  in  the  dissection  of  a  muscle  is  to  isolate  it  accu- 
rately from  all  the  surrounding  parts,  leaving  only  those  connexions  which  are  compat- 
ible with  that  object.  Since,  however,  it  is  sometimes  impossible  to  preserve  the  rela- 
tions, and  at  the  same  time  isolate  the  muscle,  it  then  becomes  necessary  to  be  provided 
with  two  preparations  for  the  demonstration  or  study  of  the  same  muscle. 

In  order  to  isolate  a  muscle,  the  surrounding  cellular  tissue,  which  often  forms  a  very 
adherent  sheath,  must  be  removed ;  and  to  do  this  completely,  1.  Make  a  section  of  the 
skin  parallel  to  the  fibres  of  the  muscle,  deep  enough  to  reach  the  muscle  through  the 
sheath;  2.  As  soon  as  the  flap  of  skin  can  be  grasped  by  the  hand,  stretch  and  separ- 
ate it  from  the  muscle  by  cutting  with  the  scalpel  in  the  angle  formed  by  these  two 
parts  ;  3.  When  the  superficial  surface  is  exposed,  proceed  to  separate  the  deep  surface, 
preserving  as  much  as  possible  all  its  important  relations  ;  4.  Then  dissect  the  extrem- 
ities, marking  out  their  limits  with  the  greatest  care. 

In  the  study  of  the  muscular  system,  great  importance  should  be  attached  to  the  choice 
of  subjects.     Robust  and  tolerably  fat  subjects  are  best  adapted  for  this  purpose. 

Preservation  of  Muscles  in  Liquids. — Alcohol,  oil  of  turpentine,  a  mixture  of  equal  parts 
of  these,  or  solutions  of  the  bichloride  of  mercury,  or  persulphate  of  iron,  may  be  em- 
ployed for  the  preservation  of  muscles,  though  they  alter  many  of  their  properties,  such 
as  their  colour,  consistence,  &.c. 

Preparations  by  Desiccation. — As  this  kind  of  preparation  requires  a  peculiar  method, 
we  refer  to  the  special  treatises  upon  anatomical  preparations  for  an  account  of  them. 
(Vide  the  works  of  MM.  Marjolin  arid  Louth.) 

Order  of  Description  of  the  Muscles. 
Before  passing  to  the  description  of  the  particular  muscles,  it  is  necessary  to  deter- 
mine in  what  order  they  shall  be  studied.  Galen  divided  the  body  for  this  purpose  into 
regions,  and  described  the  muscles  of  each  in  their  order  of  super-imposition.  In  place 
of  this  arrangement,  which  is  purely  topographical,  Vesalius  substituted  a  physiological 
one,  founded  upon  a  consideration  of  the  uses  of  the  muscles.  This  order  was  adopted 
by  Winslow,  who  named  the  different  muscular  regions  in  the  following  manner :  3fus- 
cles  which  move  the  shoulder  upon  the  trunk ;  muscles  which  move  the  arm  upon  the  scapula, 
&c.  Albinus  revived  the  method  pursued  by  Galen,  and  divided  the  muscles  into  forty- 
eight  regions  in  the  male  and  forty-six  in  the  female.  He  was  followed  by  Sabatier,  and 
by  Vicq-d'Azyr,  who  brought  the  arrangement  to  perfection  by  establishing  some  sub- 
divisions in  the  groups  formed  by  Albinus.  Thus  modified,  it  has  been  adopted  by  most 
modem  anatomists.  It  is  evidently  preferable  in  many  respects,  since  it  is  essentially 
anatomical,  and  is  best  calculated  to  exhibit  the  relations  of  the  different  muscles  and 
regions.  In  regard,  also,  to  economy  of  subjects  and  facility  of  dissection,  it  has  many 
advantages  over  the  physiological  order,  with  which,  however,  in  many  regions  it  may 
be  made  to  coincide.  We  shall,  therefore,  adopt  this  arrangement,  modifying  it  so  far 
as  to  permit  all  the  muscles  to  be  dissected  upon  one  subject ;  and,  aft;er  having  descri- 
bed all  the  muscles  according  to  their  topographical  relations,  we  shall  give  a  table  in 
which  they  will  be  grouped  in  a  physiological  order. 


198 


MYOLOGY. 


MUSCLES  OF  THE  POSTERIOR  REGION  OF  THE  TRUNK. 

TTie  Trapezius. — Latissimus  Dorsi  and  Teres  Major. — Rhomboideus. — Levator  AnguR 
Scapula. — Serrati  Postici. — Splenius. — Posterior  Spinal  Muscles. — Complexus. — Iriter- 
spinalis  Colli. — Recti  Capitis  Postici,  Major  et  Minor. — Obliqui  Capitis,  Major  et  Minor, 
— General  View  and  Action  of  the  Posterior  Spinal  Muscles. 

The  muscles  situated  on  the  posterior  region  of  the  trunk  form  several  layers,  which, 
proceeding  from  the  skin  to  the  bones,  consist,  on  either  side,  of  the  trapezius,  the  latis- 
simus dorsi  and  teres  major,  the  rhomboideus  and  levator  anguli  scapulae,  the  serrati 
postici,  superior  and  inferior,  the  splenius,  the  long  muscles  of  the  back,  viz.,  the  sacro- 
lumbalis  and  longissimus  dorsi ;  the  transversalis  colli  and  the  complexus  (which  I  re- 
gard as  two  series  of  accessory  fasciculi  to  the  longissimus  dorsi)  ;  the  complexus  ma- 
jor, the  inter-spinales  colli,  the  recti  capitis  postici,  major  et  minor,  and  the  obliqui 
.capitis,  major  et  minor.* 

The  Trapezius. 
Dissection. — 1.  Render  the  muscle  tense  by  placing  a  block  under  the  chest ;  2.  Make 
an  incision  through  the  skin  from  the  occipital  protuberance  to  the  twelfth  dorsal  verte- 
bra, and  another  horizontally  from  the  seventh  cervical  vertebra  to  the  external  end  of 
the  clavicle  ;  3.  Reflect  the  two  flaps,  together  with  the  cellular  membrane  adhering  in- 
timately to  the  muscle  ;  4.  Dissect  very  carefully  the  insertions  into  the  occipital  bone, 
which  consist  of  a  very  thin  aponeurosis  closely  united  to  the  skin. 
The  trapezius  (cucuUaris,  Alhinus,  a,  figs.  106, 113),  the  most  superficial  muscle  on  the 
Fig.  106.  posterior  region  of  the  trunk,  covers 

the  nape  of  the  neck  and  the  back. 
It  is  a  broad  triangular,  rather  than 
trapezoid  muscle,  thick  in  the  mid- 
dle, thin  and  elongated  at  its  supe- 
rior and  inferior  angles. 

Attachments. — It  arises  from  the 
spinous  processes  of  all  the  dorsal 
and  the  seventh  cervical  vertebrae, 
from  the  corresponding  supra-spi- 
nous  ligaments,  from  the  posterior 
cervical  ligament  (ligamentum  nu- 
chae;,  and  from  the  internal  third  of 
the  superior  occipital  line,  and  is  in- 
serted into  the  entire  length  of  the 
spine  of  the  scapula,  into  the  poste- 
rior border  of  the  acromion,  and  into 
the  external  third  of  the  posterior 
border  of  the  clavicle.  The  fixed 
attachments  or  origins  of  this  mus- 
cle present,  1.  A  broad,  semi-ellipti- 
cal aponeurosis,  which,  when  united 
to  the  one  on  the  opposite  side,  forms 
an  ellipse,  occupying  the  space  be- 
tween the  sixth  cervical  and  the 
third  dorsal  vertebrae  ;  2.  A  very  thin 
fibrous  lamina,  not  having  the  ordi- 
nary shining  appearance  of  an  apo- 
neurosis, which  is  firmly  adherent  to 
the  skin,  and  forms  the  truncated 
occipital  angle  of  the  muscle  ;  3.  A 
great  number  of  tendinous  fibres, 
constituting  all  those  attachments 
to  the  vertebrae  that  are  independ- 
ent of  the  two  preceding  aponeuro- 
ses. From  these  origins  all  the  fleshy 
fibres  proceed  outward,  the  inferior  fibres  from  below  upward,  the  superior  from  above 
downward,  and  from  behind  forward,  and  the  middle  ones  horizontally.  They  terminate 
in  the  following  manner  :  the  lower  or  ascending  fibres  are  collected  together,  and  at- 
tached to  a  triangular  aponeurosis,  which,  gliding  over  the  small  facette  at  the  internal 
extremity  of  the  spine  of  the  scapula,  is  inserted  into  the  tubercle  immediately  connect- 
ed with  it ;  the  middle  or  horizontal  fibres  terminate  at  the  posterior  border  of  the  spine 
of  the  scapula,  by  tendinous  fibres  which  are  very  distinct,  especially  towards  the  acro- 

*  [The  transverso-spinalis  muscle  includes  the  semi-spinalis  colli,  the  semi-spinalis  tlorsi,  and  the  multifidiu 
iminse  of  Alhinus.] 


THE   LATISSIMUS   DORSI    AND   TERES    MAJOR.  189 

mion ;  the  upper  or  descending  fibres  are  inserted  into  the  convex  portion  of  the  posterior 
border  of  the  clavicle,  many  of  them  being  also  attached  to  the  upper  surface  of  that  bone. 

Relations. — The  trapezius  is  covered  by  the  skin,  from  which  it  is  separated  by  an 
aponeurotic  lamina,  except  at  the  upper  part,  where  the  muscle  and  integuments  are 
intimately  adherent.  It  covers  the  complexus,  splenius,  rhomboideus,  and  levator  an- 
guli  scapulae,  in  the  neck ;  and  the  serratus  posticus  superior,  the  supra-spinatus,  the  pos- 
terior spinal  muscles,  and  the  latissimus  dorsi,  in  the  back.  The  most  important  rela- 
tions of  this  muscle  are  those  of  its  superior  and  external  or  occipito-clavicular  margin : 
tms  forms  the  posterior  boundary  of  the  supra-clavicular  triangle,  which  is  limited  in 
front  by  the  stemo-mastoid  muscle,  and  below  by  the  clavicle.  It  should  be  observed 
in  reference  to  the  indications  regarding  the  supra-clavicular  space,  furnished  by  this 
margin  of  the  trapezius,  that  it  sometimes  advances  as  far  as  the  middle  of  the  clavicle,  and 
has  even  been  observed  to  become  blended  with  the  posterior  edge  of  the  stemo-mastoid. 

Action. — 1.  The  upper  or  descending  portion  elevates  the  clavicle,  and,  consequently, 
the  apex  of  the  shoulder ;  but  if  the  shoulder  be  fixed,  this  portion  of  the  muscle  inclines 
the  head  to  one  side  and  extends  it,  and,  moreover,  rotates  it,  so  that  the  face  is  turned 
to  the  opposite  side.  2.  The  middle  or  horizontal  portion  carries  the  shoulder  back- 
ward, but,  from  the  obliquity  of  the  spine  of  the  scapula,  it  also  rotates  that  bone,  so  that 
the  apex  of  the  shoulder  is  carried  upward.  3.  The  lower  or  ascending  portion  draws 
the  posterior  costa  of  the  scapula  inward  and  downward  ;  and,  by  a  species  of  rotation, 
which  was  alluded  to  when  treating  of  the  scapulo-clavicular  articulations,  also  elevates 
the  apex  of  the  shoulder.  4.  When  the  whole  of  the  muscle  contracts  at  once,  the  scap- 
ula is  drawn  inward,  and  the  apex  of  the  shoulder  is  raised. 

The  Latissimus  Dorsi  and  Teres  Major. 

Dissection. — 1.  Render  the  latissimus  dorsi  tense  by  the  same  means  as  were  employ- 
ed for  the  trapezius,  and  also  by  withdrawing  the  arm  from  the  side.  2.  Make  an  incis>- 
ion  in  the  median  line  from  the  tenth  dorsal  vertebra  to  the  sacrum,  and  another  trans- 
versely from  the  same  vertebra  to  the  posterior  border  of  the  axilla,  dividing  in  the  lat- 
ter incision  a  fibro-cellular  membrane,  which  adheres  very  firmly  to  the  fleshy  fibres. 
3.  Dissect  the  humeral  insertion  very  carefully,  and  at  the  same  time  prepare  the  teres 
major,  which  is  very  intimately  related  to  this  extremity. 

The  Latissimus  Dorsi. 

The  latissimus  dorsi  (b,fig.  106,  p,figs.  109,  110)  occupies  the  lumbar  and  part  of  the 
dorsal  region,  and  the  posterior  border  of  the  axilla.  It  is  the  broadest  of  aU  the  mus- 
cles, and  shaped  like  a  triangle,  having  its  inferior  angle  truncated,  and  its  upper  and 
external  angles  considerably  elongated. 

Attachments. — It  arises  from  the  spinous  processes  of  the  last  six  or  seven  dorsal,  of 
all  the  lumbar,  and  of  the  sacred  vertebrae,  from  the  posterior  third  of  the  crest  of  the 
ilium,  and  from  the  last  four  ribs,  and  is  inserted  into  the  bottom  of  the  bicipital  groove 
of  the  humerus,  not  into  its  posterior  border. 

Its  origin  from  the  crest  of  the  ilium  and  from  the  vertebrae  is  effected  through  the 
medium  of  a  triangular  aponeurosis,  narrow  and  thin  above,  broad  and  very  strong  be 
low,  where  it  is  blended  with  the  aponeuroses  of  the  serratus  posticus  inferior  and  ob 
liquus  intemus  abdominis,  and  with  the  posterior  layer  of  the  aponeurosis  of  the  trans- 
versus  abdominis.  This  aponeurosis  assists  in  forming  the  sheath  of  the  sacro-lumbalis, 
longissimus  dorsi,  and  trans verso-spinalis.  The  costal  origins  consist  of  fleshy  tongues 
or  digitations,  which  are  interposed  between  similar  processes  of  the  external  oblique. 
From  this  threefold  origin  the  fleshy  fibres  proceed  in  the  following  manner :  the  upper 
pass  horizontally,  the  middle  are  directed  obliquely,  and  the  lower  vertically  upward ; 
they  all  converge,  so  as  to  form  a  thick  fasciculus,  directed  towards  the  inferior  angle 
of  the  scapula,  from  which  it  often  receives  some  accessory  fibres.  The  muscle  is  then 
twisted  upon  itself,  so  that  the  inferior  or  vertical  fibres  become  first  anterior  and  then 
superior,  while  the  superior  or  horizontal  fibres  become  first  posterior  and  then  inferior. 
This  torsion  may  perhaps  be  intended  to  prevent  displacement  of  the  fibres.  They  all 
terminate  in  a  flat  quadrilateral  tendon,  which  is  inserted  into  the  bottom  of  the  bicip- 
ital groove,  above  the  insertion  of  the  tendon  of  the  pectoralis  major.  This  tendon  fur- 
nishes a  fibrous  expansion  continuous  with  the  fascia  of  the  arm,  and  also  a  band  which 
extends  to  the  lesser  tuberosity  of  the  humerus. 

Relations. — This  muscle  is  covered  by  the  skin  (from  which  it  is  separated  by  a  close- 
ly-adherent fibro-cellular  sheath),  and  by  the  inferior  angle  of  the  trapezius.  It  covers 
the  posterior  spinal  muscles,  the  serratus  posticus  inferior,  the  external  intercostals,  the 
serratus  magnus,  the  lower  angle  of  the  scapula,  the  rhomboideus,  and,  lastly,  the  teres 
major,  by  which  muscle  it  is  itself  covered  in  its  turn.  Its  external  margin  is  in  relation 
with  the  posterior  border  of  the  external  oblique,  from  which  it  is  separated  below  by  a 
small  triangular  interval.  The  upper  part  of  the  external  margin,  together  with  the  teres 
major,  forms  the  posterior  border  of  the  axilla ;  and  from  the  same  margin  a  muscular  fasci- 
culus occasionally  extends  beneath  the  axilla  to  the  lower  edge  of  the  pectoralis  major. 


mtfO  MYOLOGY. 

The  Teres  Major. 

This  muscle  (c  c,Jig.  106),  which,  both  in  its  uses  and  its  anatomical  arrangements, 
should  be  considered  an  accessory  to  the  latissimus  dorsi,  is  situated  behind  the  shoulder. 

Attachments.— It  arises  from  the  quadrilateral  surface,  situated  at  the  inferior  angle  of 
the  scapula,  to  the  outer  side  of  the  infra-spinous  fossa,  and  is  inserted  into  the  josterior 
border  of  the  bicipital  groove.  The  scapular  attachment  consists  of  short  tendinous 
fibres,  some  of  which  are  fixed  directly  to  the  bone,  and  some  into  the  fasciae,  which 
separate  this  muscle  from  those  of  the  infra-spinous  and  subscapular  fossae.  The  fleshy 
fibres  arising  from  these  different  attachments  form  a  thick  fasciculus,  flattened  from  be- 
fore backward,  not  cylindrical,  and  about  two  or  three  fingers  in  bieadth,  which  is  direct- 
ed outward  and  upward,  and  becomes  slightly  twisted,  so  as  to  be  inserted  by  a  broad 
and  flat  tendon  into  the  posterior  border  of  the  bicipital  groove. 

Relations. — The  latissimus  dorsi  at  first  covers  its  scapular  extremity,  and  then,  turn- 
ing round  its  lower  edge,  becomes  anterior  to  it.  The  tendon  of  the  latissimus  dorsi  is, 
therefore,  applied  to  the  anterior  surface  of  the  tendon  of  the  teres  major ;  but  since  the 
former  is  attached  to  the  bottom,  and  sometimes  even  to  the  anterior  border  of  the  bi- 
cipital groove,  and  the  latter  to  the  posterior  border  of  the  same  groove,  they  are  separ- 
ated at  their  insertions  by  an  interval,  in  which  there  is  almost  always  a  synovial  mem- 
brane, and  which  forms  a  true  cul-de-sac  below,  for  the  lower  margins  of  the  two  tendons 
are  blended  together. 

The  posterior  surface  of  the  teres  major  is  covered  by  the  skin,  from  which  it  is  sep 
arated  on  the  inside  by  the  latissimus  dorsi,  and  externally  by  the  long  head  of  the  tri- 
ceps. Its  anterior  surface  is  in  relation  with  the  subscapularis,  the  coraco-brachialis, 
the  short  head  of  the  biceps,  the  brachial  plexus,  the  axillary  vessels,  and  the  cellular 
tissue  of  the  axilla.  Its  upper  margin  is  at  first  in  contact  with  the  teres  minor,  from 
which  it  is  separated  above  by  the  long  head  of  the  triceps  ;  its  lower  margin  forms,  in 
conjunction  with  the  latissimus  dorsi,  the  posterior  border  of  the  axilla. 

Action  of  the  Latissimus  Dorsi  and  Teres  Major. — The  latissimus  dorsi  adducts  the 
arm,  rotates  it  inward,  and  at  the  same  time  draws  it  backward  (hence  its  name,  ant 
scalptor).  When  only  the  upper  or  horizontal  fibres  contract,  the  arm  is  carried  inward 
and  backward  ;  when  the  lower  fibres  act  alone,  it  is  carried  downward. 

The  uses  of  the  teres  major  are  precisely  similar  to  those  of  the  latissimus  dorsi,  to 
which  it  is  congenerous  and  accessory,  and  with  which  it  is  always  associated  in  ac- 
tion, drawing  the  humerus  inward,  backward,  and  downward.  When  the  humerus  is 
the  fixed  point,  the  latissimus  dorsi  raises  the  trunk,  and  with  the  greater  facility,  be- 
cause it  is  attached  to  the  ribs,  the  spine,  and  the  pelvis.  In  consequence  of  its  costal 
attachments,  the  latissimus  dorsi  is  a  muscle  of  inspiration ;  and  it  should  be  observed, 
that  the  direction  of  its  fibres,  which  is  almost  perpendicular  to  the  ribs,  enables  it  to 
act  with  great  power. 

The  Rhomboideus. 

Dissection. — Divide  the  trapezius  by  an  incision  extending  from  the  third  dorsal  ver- 
tebra to  the  lower  angle  of  the  scapula ;  dissect  back  the  flaps,  taking  care  to  remove  a 
fibro-cellular  layer  which  adheres  closely  to  the  trapezius. 

The  rhomboideus  {d  d,  fig.  106),  situated  in  the  dorsal  region,  on  the  posterior  aspect 
of  the  trunk,  approaches  closely  to  the  form  of  a  rhomboid  or  lozenge  ;  it  is  broad  and 
thin,  but  thicker  below  than  above,  and  is  almost  always  divided  into  two  parts. 

Attachments. — It  arises  from  the  bottom  of  the  ligamentum  nuchae,  from  the  spinous 
processes  of  the  seventh  cervical  and  five  superior  dorsal  vertebrae,  and  from  the  corre- 
sponding interspinous  ligaments,  and  is  inserted  into  all  that  part  of  the  posterior  costa 
of  the  scapula  situated  below  its  spine.  The  spinal  or  internal  attachments  consist  of 
tendinous  fibres,  the  most  inferior  of  which  are  the  longest.  From  these  points  the 
fleshy  fibres  proceed,  parallel  to  each  other,  downward  and  outward,  to  a  very  thin  ten- 
don, which  runs  along  the  posterior  costa  of  the  scapula,  but  only  adheres  to  it  above 
and  below :  the  greater  number  of  fibres  are  inserted  into  the  lower  angle  of  the  scapula 
by  a  very  strong  tendon,  which  forms  the  principal  attachment  of  the  muscle,  and  to 
wliich  the  tendon  mentioned  above  is  merely  subordinate.  The  upper  part  of  this  mus- 
cle {e,fig.  103),  which  arises  from  the  hgamentum  nuchae  and  the  seventh  cervical  ver- 
tebra, is  inserted  by  itself  opposite  the  spine  of  the  scapula.  It  is  distinct  from  the  re- 
mainder of  the  muscle,  and  from  this  fact  Vesalius,  Albinus,  and  Scemmering  gave  it 
the  name  of  rhomboideus  minor  or  superior. 

Relations. — This  muscle  is  covered  by  the  trapezius,  the  latissimus  dorsi,  and  the 
skin.  It  covers  the  serratus  posticus  superior,  part  of  the  posterior  spinal  muscles,  the 
ribs,  and  the  intercostal  muscles. 

Action. — ^The  rhomboid  raises  the  scapula  and  draws  it  inward.  As  it  acts  principal- 
ly upon  the  lower  angle  of  that  bone,  it  rotates  it  in  such  a  manner  that  the  anterior 
angle,  and,  consequently,  the  apex  of  the  shoulder,  is  depressed.  It  assists  the  trape- 
zius in  carrying  the  entire  shoulder  inward,  and  is  also  associated  with  the  upper  fibres 


THE   SERRATI   POSTICI.  201 

of  the  same  muscle  in  raising  that  part ;  hut,  on  the  other  hand,  it  antagonizes  the  tra- 
pezius by  depressing  the  apex  of  the  shoulder. 

The  Levator  Anguli  Scapulcs. 

Dissection. — Detach  the  trapezius  from  the  spine  of  the  scapula  with  care  ;  divide  the 
upper  part  of  the  sterno-mastoid,  so  as  to  expose  the  transverse  processes  of  the  three 
or  four  superior  cervical  vertebrae. 

The  levator  anguli  scapula  (levator  scapulae,  Alhinus,  f,figs.  106,  110,  113,  114),  situ- 
ated at  the  posterior  and  lateral  part  of  the  neck,  is  an  elongated  bundle,  having  its  up- 
per portion  flattened  from  without  inward,  and  divided  into  three  or  four  fasciculi,  while 
the  lower  part  is  flattened  from  behind  forward. 

Attachments. — It  arises  from  the  posterior  tubercles  of  the  transverse  processes  of  the 
three  or  four  superior  cervical  vertebrae,  externally  to  the  splenius,  and  behind  the  sca- 
lenus posticus  ;  it  is  inserted  into  the  superior  angle  of  the  scapula  (whence  its  name), 
and  into  all  that  portion  of  its  internal  costa  situated  above  the  spine. 

The  cervical  attachments  of  this  muscle  consist  of  four  tendons,  to  which  succeed  an 
equal  number  of  fleshy  fasciculi,  at  first  distinct,  but  afterward  united  into  one  bundle, 
which  proceeds  downward,  backward,  and  outward,  and  spreads  out  to  be  inserted  into 
the  scapula  by  short  aponeurotic  fibres. 

Relations. — It  is  covered  by  the  trapezius,  the  sterno-mastoid,  and  the  skin  ;  and  it 
lies  superficially  to  the  splenius,  the  sacro-lumbalis,  the  transversalis  colli,  and  the  ser- 
ratis  posticus  superior. 

Action. — When  its  upper  attachment  is  fixed,  this  muscle  carries  the  posterior  angle 
of  the  scapula  upward  and  forward,  and,  consequently,  rotates  that  bone,  so  as  to  depress 
the  apex  of  the  shoulder.  It  conspires  with  the  rhomboid  and  the  trapezius  in  elevating 
the  entire  shoulder,  and  with  the  rhomboid  in  depressing  its  apex,  in  this  respect  acting 
as  an  antagonist  to  the  trapezius.  When  the  fixed  point  is  below,  which  must  be  very 
rarely,  it  inclines  the  neck  backward  and  to  its  own  side. 

The  Serrati  Postici. 

These  are  two  in  number,  a  superior  and  an  inferior. 

Dissection. — 1.  To  expose  the  superior  muscle,  divide  and  reflect  the  trapezius  and  the 
rhomboid,  and  draw  the  scapula  forward ;  2.  To  display  the  inferior,  raise  the  latissimus 
dorsi  with  great  care,  as  its  deep  aponeurosis  is  blended  with  that  of  the  serratus  posticus 
inferior  ;  3.  Preserve  the  thin  aponeurosis  extending  between  the  two  serrati  muscles.* 

1.  The  serratus  posticus  superior  is  situated  at  the  upper  and  back  part  of  the  thorax, 
and  is  of  an  irregularly-quadrilateral  figure. 

Attachments. — It  arises  from  the  ligamentum  nuchae  and  the  spinous  processes  of  the 
seventh  cervical  and  of  the  two  or  three  upper  dorsal  vertebrae,  and  is  inserted  into  the 
upper  borders  of  the  second,  third,  fourth,  and  fifth  ribs.  The  vertebral  attachment  con- 
sists of  a  very  thin  aponeurosis,  the  fibres  of  which  are  parallel,  and  inclined  downward 
and  outward.  From  this  aponeurosis,  which  constitutes  at  least  the  inner  half  of  the 
muscle,  the  fleshy  fibres  proceed  in  the  same  direction,  and  almost  immediately  divide 
into  four  digitations,  which  are  inserted  into  the  ribs  by  means  of  short  tendinous  fibres. 
The  superior  digitation  is  attached  near  the  angle  of  the  corresponding  rib,  and  each  of 
the  others  at  successively  greater  distances  from  it. 

2.  The  serratus  posticus  inferior  (lumbo-costalis,  Chaussier,  g,  fig.  106)  is  also  of  an  ir- 
regularly-quadrilateral form,  and  is  situated  at  the  lower  part  of  the  back  and  the  upper 
part  of  the  loins.  It  arises  from  the  spinous  processes  of  the  two  lower  dorsal  and  three 
upper  lumbar  vertebrae,  and  is  inserted  into  the  inferior  borders  of  the  last  four  ribs.  The 
vertebral  or  internal  attachment  consists  of  an  aponeurosis  similar  to  that  of  the  prece- 
ding muscle,  but  its  fibres  have  an  inverse  direction,  i.  e.,  obliquely  outward  and  upward. 
From  this  aponeurosis,  which  forms  the  internal  half  of  the  muscle,  the  fleshy  fibres  pro- 
ceed in  the  same  direction,  and  divide  into  four  flat  digitations,  progressively  decreasing 
in  size  from  above  downward,  which  are  inserted  into  the  ribs  by  means  of  tendinous 
laminae,  the  superior  digitation  near  the  angle  of  its  corresponding  rib,  and  the  others, 
successively,  farther  beyond  it. 

Relations. — These  two  muscles  have  certain  relations  in  common,  and  there  am  some 
peculiar  to  each.  They  both  cover  the  longissimus  dorsi,  the  sacro-lumbalis,  the  trans- 
verso-spinalis,  the  ribs,  and  the  corresponding  intercostal  muscles.  The  superior  is  cov- 
ered by  the  rhomboideus,  the  trapezius,  and  the  serratus  magnus,  and  covers  the  splenius 
and  transversalis  colli.  The  inferior  is  covered  by  the  latissimus  dorsi,  with  the  apo- 
neurosis of  which  muscle  its  own  aponeurotic  lamina  is  so  closely  united  that  it  is  impos- 
sible to  separate  them  completely  ;  and  it  covers  the  posterior  layer  of  the  aponeurosis 
of  the  transversalis. 

Action. — Besides  certain  common  uses,  each  muscle  has  its  own  peculiar  action.     One 

*  [This  exceedingly  thia  and  semi-transparent  lamella  has  received  the  name  of  the  vertebral  aponewrotit 

Sep  A.P0NEUK0I.0OY.] 

Cc 


202  MYOLOGY. 

impoitant  common  use  is,  to  retain  in  the  vertebral  groove  those  muscles  of  the  back 
which,  from  their  extreme  length,  are  the  most  liable  to  displacement.  This  effect  is 
produced  by  their  fleshy  portions  rendering  tense  their  aponeurotic  expansions. 

With  regard  to  the  actions  proper  to  each,  1.  The  superior  elevates  those  ribs  into 
which  it  is  inserted,  and  is,  consequently,  a  muscle  of  inspiration  ;  2.  The  inferior,  on 
the  other  hand,  is  a  depressor  of  the  ribs,  and,  therefore,  a  muscle  of  expiration. 

The  Splenius. 

Dissection. — Merely  remove  the  trapezius,  the  rhomboid,  and  the  serratus  posticus  su- 
perior. 

The  splenius  {i,Jigs.  106,  113,  114),  so  named  because  it  has  been  compared  to  the 
spleen  {a■!T^v),  is  situated  at  the  posterior  part  of  the  neck  and  upper  part  of  the  back.  It 
is  a  broad  muscle,  terminating  in  a  point  below,  and  dividing  into  two  portions  above. 

Attachments. — It  arises  from  the  spinous  processes  of  the  four  or  five  superior  dorsal 
and  the  seventh  cervical  vertebra,  from  the  corresponding  supra-spinous  ligaments,  and 
also  from  the  ligamentum  nuchae,  between  the  seventh  and  the  third  cervical  vertebrae  ; 
it  is  inserted,  1.  Into  the  transverse  processes  of  the  first,  second,  and  often  the  third  cer- 
vical vertebrae  ;  2.  Into  the  external  surface  and  posterior  border  of  the  mastoid  process, 
and  the  external  third  of  the  rough  space  beneath  the  superior  semicircular  line  of  the 
occipital  bone.  The  spinal  attachments  consist  of  tendinous  fibres,  the  most  inferior  of 
which  are  the  longest.  From  these  the  fleshy  fibres  proceed  obliquely  upward  and  out- 
ward, the  lower  being  longer  and  more  vertical,  and  form  a  broad,  flat  muscle,  which  is 
much  thicker  externSly,  and  soon  becomes  divided  into  two  portions  :  one  smaller,  infe- 
rior and  external ;  the  other  much  larger,  superior  and  internal.  The  former  is  called 
the  splenius  colli ;  it  is  sometimes  distinct,  even  from  its  origin,  and  soon  subdivides 
into  two  or  three  fasciculi,  which  terminate  in  as  many  tendinous  processes,  that  are  in- 
serted into  the  atlas,  the  axis,  and  often  into  the  third  cervical  vertebra.  The  fascicu- 
lus proceeding  to  the  atlas  is  usually  the  largest.  The  second,  or  the  upper  and  internal 
portion  of  the  muscle,  is  connected  with  the  head,  and  is  called  the  splenius  capitis. 

Relations. — The  splenius  is  covered  by  the  trapezius  (the  rhomboid  and  the  serratus 
posticus  superior  intervening  below),  by  the  sterno-mastoid,  and  by  the  levator  anguli 
scapulae.  It  covers  the  complexus,  the  longissimus  dorsi,  the  transversalis  colli,  and 
the  trachelo-mastoid.  The  levator  anguli  scapulae  is  in  contact  with  its  outer  border, 
and  rests  upon  it  above,  the  cervical  insertions  of  the  two  muscles  being  blended  togeth- 
er ;  below  they  are  separated  by  the  transversalis  colli  and  sacro-lurabalis.  The  inter- 
nal edge  is  very  thin,  and  separated  from  the  muscle  of  the  opposite  side  by  a  triangu- 
lar interval,  in  which  the  complexi  are  visible. 

Actions. — The  splenius  extends  the  head,  inclines  it  to  its  own  side,  and  rotates  it  so 
that  the  face  is  turned  to  the  same*ide.  This  action  of  the  splenius  depends  on  its  at- 
tachments to  the  occipital  bone,  the  mastoid  process,  and  the  atlas.  By  its  insertions 
into  the  second  and  third  cervical  vertebrae  it  tends  to  rotate  these  in  the  same  direction. 
When  the  two  muscles  act  together,  the  head  is  drawn  directly  backward.  The  splenius 
is  therefore  an  extensor  and  rotator  of  the  head  and  of  the  neck ;  it  assists  in  supporting 
the  head  in  the  erect  position,  and  prevents  it  from  inclining  forward  in  obedience  to  the 
force  of  gravity. 

The  Posterior  Spinal  Muscles. 

As  these  muscles  are  arranged  in  a  peculiar  manner,  we  shall  adopt  a  method  of  de- 
scription in  some  measure  different  from  that  which  we  have  elsewhere  employed. 

The  posterior  spinal,  or  long  muscles  of  the  back  (see  Jig.  107),  are  three  in  number, 
viz.,  the  sacro-lumbalis,  the  longissimus  dorsi,  and  the  transverso-spinalis  muscle. 

These  three  muscles,  which  extend  the  entire  length  of  the  spine,  form  a  very  large 
muscular  mass,  completely  filling  up  the  corresponding  vertebral  groove.  This  mass  is 
small  at  the  lower  part  of  the  sacral  groove,  becomes  much  enlarged  in  the  loins,  then 
diminishes  in  the  back,  and  again  acquires  a  considerable  size  in  the  neck.  Chaussier 
has  given  a  description  of  them  under  the  collective  name  of  the  sacrospinal  muscle ; 
and  they  have  also  been  denominated  the  erector  spina. 

I  shall  describe  the  three  muscles  together  ;  but,  in  order  to  adopt  some  arrangement 
in  a  matter  so  complicated,  I  shall  divide  them  into  three  portions,  viz.,  a  lumbro-sacral, 
a  thoracic,  and  a  cervical. 

Ltimhro-sacral  Portion  of  the  Posterior  Spinal  Muscles. 
Dissection. — 1.  Render  this  portion  of  the  muscle  tense,  by  placing  a  block  under  the 
abdomen.  2.  Divide  by  a  vertical  incision  the  trapezius,  splenius,  rhomboideus,  latis- 
simus  dorsi,  and  serrati  postici ;  reflect  the  divided  portions  inward  and  outward.  A 
young  subject,  from  ten  to  twelve  years  of  age,  is  best  adapted  for  the  study  of  these 
muscles,  from  the  facility  with  which  the  different  fasciculi  may  be  separated.  For  the 
same  reason,  one  that  is  much  infiltrated  with  serum  is  preferable  to  one  in  which  the 
parts  are  dry.  i  - 


THE    POSTERIOE   SPINAL   MUSCLES. 


203 


The  lumbo-sacral  portion  is  usually  called  the  common  m/iss  of  the  sacro-lumbalis  and 
longissimus  dorsi.  It  forms  the  fleshy  part  of  the  loins,  and  is  called  the  fdlet  in  the  low- 
er animals  :  it  is  the  most  highly  developed  in  man,  in  whom  it  exerts  a  constant  and 
powerful  action  during  the  erect  posture  :  it  appears  to  be  the  coimnon  origin  of  the  pos- 
terior spinal  muscles,  whence  the  name  of  common  mass :  it  fills  up  entirely  the  lumbo- 
sacral groove,  and  even  projects  backward  and  laterally  in  robust  subjects. 

It  is  of  small  size  in  the  sacral  region,  is  much  enlarged  at  the  middle  of  the  lumbar 
region,  at  the  upper  part  of  which  it  again  diminishes,  so  as  to  resemble  two  cones  uni- 
ted by  their  bases. 

Attachments.  —  The  common  mass  arises  from  the  whole  extent  of  the  sacro-iliac 
groove,  and  from  the  anterior  surface  and  external  border  of  an  extremely  strong  apo- 
neurosis, formed  of  parallel  vertical  fibres,  and  strengthened  by  a  superficial  layer  direct- 
ed obliquely.  This  aponeurosis  of  origin  for  the  posterior  spinal  muscles  {d,fig.  107)  is  in- 
serted on  the  inside  to  the  sacral  ridge,  to  the  summits  of  the  spinous  processes  of  the 
lumbar  and  three  lower  dorsal  vertebrae,  and  to  the  corresponding  supra-spinous  liga- 
ments :  on  the  outside,  to  the  series  of  eminences  representing  the  transverse  processes 
of  the  sacral  vertebrae,  and  to  the  back  part  of  the  crest  of  the  ilium  :  it  gives  attach- 
ment to  many  of  the  fibres  of  the  glutaeus  maximus.  It  is  short  on  the  outside,  and  very 
long  on  the  inside,  reaching  in  the  latter  direction  to  the  middle  of  the  dorsal  region,  un- 
der the  form  of  parallel  and  regular  bands  {d,fig.  107). 

Arising  from  these  different  origins,  the  coiimion  mass  appears  at  first  extremely  sim 
pie  in  its  composition,  consisting  of  fibres  passing  vertically  upward.  But  if  the  aponeu- 
rosis be  detached  from  its  spinal  insertions,  and  turned  outward,  it  will  be  seen  that  the 
common  mass  is  essentially  composed  of  two  portions  :  one  internal  and  anterior,  the 
lumbosacral  portion  of  the  transverso-spinalis ;  and  the  other  external  and  posterior,  the 
lumio  sacral  portion  of  the  sacro-lumbalis  and  longissimus  dorsi. 

1.  The  lumbosacral  portion  of  the  transverso-spinalis*  occupies  all  the  sacral  groove,  and 
that  part  of  the  lumbar  groove  situated  within  the  articular  processes.  It  is  perfectly 
distinct  in  the  loins,  being  separated  from  the  common  mass  by  loose  cellular  tissue  trav- 
ersed by  vessels  and  nerves.  It  arises  from  the  articular  processes  of  the  lumbar  verte- 
brae by  flat  tendons,  directed  obliquely  inward  and  upward,  and  terminating  upon  the  pos- 
terior surface  of  the  muscle :  by  the  imion  of  their  contiguous  edges  an  aponeurosis  is 
formed,  which  is  itself  blended  along  one  of  its  borders  with  the  deep  surface  of  the  com- 
mon aponeurosis  of  origin.  From  these  tendons  the 
fleshy  fibres  arise,  and  having  united  into  bundles, 
terminate  by  other  tendons  at  the  spinous  processes 
of  the  vertebrae  above.  In  the  sacral  region  this 
portion  of  the  transverso-spinaUs  is  less  distinct,  but 
it  may  be  easily  seen  that  it  occupies  the  whole  of 
the  sacral  groove,  and  that  the  corresponding  por- 
tion of  the  aponeurosis  of  origin  affords  attachments 
fo  it  alone. 

2.  The  external  and  posterior  portion  of  the  com- 
mon mass,  or  lumbosacral  portion  of  the  sacro-lumbalis 
and  longissimus  dorsi,  is  entirely  without  the  sacral 
groove,  but  occupies  that  part  of  the  lumbar  groove 
situated  on  the  outer  side  of  the  articular  processes. 

It  arises,  1.  From  all  the  lumbar  portion  of  the  com- 
mon aponeurosis.  2.  From  an  extremely  strong  ten- 
don, which  is  attached  to  the  posterior  superior  spi- 
nous process  of  the  ilium.  3.  From  the  posterior  s~ 
fourth  of  the  crest  of  the  ilium,  internally  by  tendi- 
nous, and  externally  by  muscular  fibres.  The  thick 
fleshy  mass  proceeding  from  these  different  origins 
is  disposed  of  in  the  following  manner :  the  greater 
part  of  the  fibres  pass  directly  upward  to  the  dorsal 
region,  forming  the  proper  commencement  of  the 
sacro-lumbalis  (a  a,  fig.  107).  The  remaining  fibres 
are  directed  forward,  and  are  arranged  into  two  sets 
of  bundles,  one  of  which  is  inserted  into  the  summits 
of  the  transverse  processes,  forming  the  external  or 
transverse  fasciculi ;  and  the  other  into  the  tubercles 
of  the  articular  processes,  forming  the  internal  or  ar- 
ticular fasciculi.  These  two  sets  of  fibres  constitute 
the  proper  origin  of  the  longissimus  dorsi  (d  d,  fig. 
107). 

Relations. — The  common  mass  is  covered  behind 


Fiff.  107. 


[This  corresponds  to  the  inferior  or  lumbo-sacral  fasciculi  of  the  multifidus  spinte,] 


204  MYOLOGY. 

by  the  united  aponeuroses  of  the  latissimus  dorsi  and  serratus  posticus  inferior,  and  by 
the  posterior  layer  of  the  aponeurosis  of  the  transversalis ;  in  front,  it  corresponds  to 
the  lumbar  groove,  the  inter-transversales  muscles  of  the  loins,  and  the  middle  layer  of 
the  aponeurosis  of  the  transversalis,  which  separates  it  from  the  quadratus  lumborum  ; 
on  the  inside,  it  corresponds  to  the  spinous  processes  ;  and  on  the  outside,  to  the  angle 
of  union  between  the  posterior  and  middle  layers  of  the  aponeurosis  of  the  transversalis. 
In  this  way  it  is  completely  enclosed  in  an  osteo-fibrous  sheath. 

Thoracic  Portion  of  the  Posterior  Spinal  Muscles. 

The  transverso-spinalis  muscle  may  be  completely  isolated  from  the  others  in  this 
region.  We  have  seen  the  distinction  between  the  sacro-lumbalis  and  longissimus  dorsi 
commenced  at  the  upper  part  of  the  lumbar  region ;  in  the  back  they  are  completely  sep- 
arated by  some  loose  cellular  tissue  and  the  posterior  branches  of  the  dorsal  nerves  and 
vessels. 

The  thoracic  portion  of  the  sacro-lurnbalis  (6  V,  fig.  107)  consists  of  a  continuation  of  the 
vertical  or  external  fibres  of  the  common  mass  ;  as  it  proceeds  upward  it  becomes  more 
and  more  slender,  and  is  divided  into  a  series  of  fasciculi,  which  are  inserted  succes.sive- 
iy  into  the  angles  of  the  ribs,  by  means  of  tendinous  prolongations,  that  extend  for  a 
considerable  distance  upon  the  posterior  surface  of  the  muscle.  It  was  the  existence  of 
these  aponeurotic  processes,  the  contiguous  edges  of  which  are  often  united,  that  in- 
duced Winslow  to  compare  the  muscle  to  a  palm  leaf  In  this  manner  the  muscular 
fasciculi  are  soon  expended,  terminating  at  about  the  sixth  rib,  but  the  muscle  itself  is 
continued  into  the  neck  by  means  of  accessory  fibres,  which  may  be  exposed  by  turning 
the  muscle  outward,  sifter  separating  it  from  the  longissimus  dorsi  (as  at  h') :  twelve 
long,  thin  tendons  will  then  be  seen  to  arise  from  the  upper  portion  of  the  angles  of  the 
twelve  ribs,  and  to  pass  outward  and  upward  :  to  these  succeed  fleshy  fasciculi,  which 
terminate  in  aponeurotic  processes,  situated  on  their  posterior  surfaces,  and  having  pre- 
cisely the  opposite  direction.  These  accessory  bundles  (c  c',Jig.  107;  i,fig.  108)  have 
been  very  well  described  by  Diemerbroek  under  the  name  ofcervicales  descendens,  and  by 
Steno  under  that  of  musculus  accessorius  ad  sacro-lumbalem ;  the  four  or  five  superior  bun- 
dles form  the  transversaire  grele  of  Winslow,  and  the  cervicalis  descendens  of  Albinus. 

The  thoracic  portion  of  the  longissimus  dorsi  (e  e',  fig.  107)  is  larger  than  the  preceding 
muscle,  to  the  inner  side  of  which  it  is  situated  :  it  diminishes  much  less  rapidly,  because 
the  common  aponeurosis  {d)  is  extended  in  the  form  of  bands  upon  its  posterior  aspect, 
which  afford  attachment  to  additional  fleshy  fibres.  This  muscle  is  a  continuation  of  the 
internal  or  articular,  and  the  external  or  transverse  fasciculi,  described  as  existing  in 
the  lumbar  region,  and  is  itself  divided  into  three  orders  of  fasciculi,  one  external  and  two 
internal.  1.  The  external  or  costal  fasciculi  form  the  continuation  of  the  transverse  bun- 
dles of  the  lumbar  portion  of  the  muscle,  and  are  inserted  by  very  thin  tendons  into  the 
space  between  the  angles  of  the  ribs  and  the  summits  of  the  dorsal  transverse  processes 
(e',fig.  107).  2.  The  first  set  of  internal,  or  the  spinous  fasciculi,  are  inserted  into  the  spi- 
nous processes  of  the  five  or  six  superior  dorsal  vertebrae  ;  and  as  they  arise  from  tendi- 
nous bands  attached  to  the  summits  of  the  spinous  processes  of  the  lower  dorsal  vertebrae, 
and  of  that  of  the  first  lumbar  vertebra,  Winslow  considered  them  as  forming  a  separate 
muscle,  which  he  called  le  long  epineux  du  dos  (spinalis  dorsi, /,^o'.  107).  3.  The  second 
set  of  internal,  or  the  transverse  fasciculi,  are  a  continuation  of  the  articular  fasciculi  of  the 
lumbar  region ;  they  constituie  the  principal  termination  of  the  longissimus  dorsi,  and 
are  attached  by  very  long  and  thin  tendons  to  the  transverse  processes  of  the  dorsal 
vertebrae. 

The  thoracic  portion  of  the  transverso-spinalis*  (partly  seen  in^^.  108)  is  reduced  to  a 
very  narrow  band,  concealed  by  the  longissimus  dorsi :  it  arises  by  very  long  and  delicate 
tendons  from  the  lower  dors^  transverse  processes,  and  is  inserted  by  others  equally 
sinailar,  long  and  slender,  into  the  summits  of  the  superior  dorsal  spinous  processes, 
some  pale  fleshy  fibres  connecting  the  two  series  of  tendons. 

Connexions. — The  dorsal  portion  of  the  posterior  spinal  muscles  entirely  fills  the  dor- 
sal groove,  limited  on  the  outer  side  of  the  angles  of  the  ribs.  They  are  covered  by 
several  muscular  layers,  the  nearest  of  which  is  formed  by  the  two  serrati  postici  and 
their  connecting  aponeurosis,  which  completes  the  sheath  enclosing  the  long  muscles  of 
the  back  :  they  are,  moreover,  separated  from  the  skin  by  the  rhomboid,  trapezius,  and 
latfssimus  dorsi. 

The  Cervical  Portion  of  the  Posterior  Spinal  Muscles,  the  Transversalis   Colli,  and  the 

Trachelo-mastoidcus. 
Cervical  portion  of  the  sacro-lumbalis,  or  cervicalis  descendens.  The  sacro-lumbalis, 
whose  original  fibres  are  found  to  terminate  at  and  upon  the  sixth  rib,  is  continued,  by 
means  of  its  accessory  fasciculi  (c  c',fig.  107),  up  to  the  transverse  processes  of  the  four 
or  five  inferior  cervical  vertebrae  (i,fig.  108),  into  the  summits  of  which  it  is  inserted  by 
very  slender  tendons.     The  number  of  these  terminating  fasciculi  varies  in  a  remarkable 

*  [This  corresponds  to  the  semi-spinalis  do.rs-,  and  to  the  dorsal  portion  of  the  multifidus  spinsn  of  Albinus  ■• 


THE    POSTERIOR  SPINAL  AND   COMPI.EXUS    MUSCLES.  205 

manner.  Indeed,  the  splenius,  the  transverscdis  colli,  the  sacro-lumbalis,  and  even  the 
levator  anguli  scapulas,  are  so  closely  connected,  that,  upon  examining  their  cervical  in- 
sertions only,  these  might  all  be  ascribed  to  a  single  muscle.  The  cervical  portion  of 
the  sacro-lumbalis  is  covered  by  the  levator  anguli  scapulae,  and  can  only  be  exposed  by 
turning  this  muscle  outward. 

The  cervical  portion  of  the  longissimus  dorsi,  or  the  transverscdis  colli,  and  the  tra- 
chelo-mastoid.  The  extent  of  the  longissimus  dorsi  is  limited  to  the  back ;  its  highest 
internal  or  spinous  fasciculus  seldom  reaches  the  spinous  process  of  the  first  dorsal  ver- 
tebra :  its  highest  external  or  costal  fasciculus  is  attached  to  the  second,  sometimes  even 
to  the  fourth  rib,  and  its  highest  transverse  fasciculus  is  inserted  into  the  transverse 
process  of  the  first  dorsal  vertebra.  In  some  very  rare  cases,  a  few  internal  fasciculi 
reach  the  cervical  vertebrae  :  I  have  seen  one  of  them  terminate  by  becoming  attached 
both  to  the  transverse  process  of  the  third  cervical  vertebra  and  to  the  complexus.  The 
longissimus  dorsi  is,  however,  prolonged  by  accessory  fasciculi  as  far  as  the  third  cervi- 
cal vertebra.  These  fasciculi  can  only  be  identified  by  their  direction  (for  they  can  never 
be  completely  separated  from  this  muscle) :  they  form  a  distinct  muscle,  known  as  the 
transverscdis  colli  (transversalis  cervicis,  Albinus,  g  g,fig.  107). 

By  reflecting  outward  the  upper  part  of  the  longissimus  dorsi,  they  may  be  exposed, 
varying  in  number,  and  arising  from  the  summits  of  the  transverse  processes  of  the  third, 
fourth,  fifth,  sixth,  and  sometimes  seventh  and  eighth  dorsal  vertebrae,  by  long,  thin  ten- 
dons, and  inserted  by  other  tendons  into  the  posterior  tubercles  of  the  transverse  pro- 
cesses of  the  five  inferior  cervical  vertebras  {I,  fig.  108) :  the  transversalis  colli  is  covered 
by  the  longissimus  dorsi,  the  splenius,  and  levator  anguli  scapulae,  and  rests  upon  the 
trachelo-mastoid  and  complexus. 

The  trachelo-vtastoideus  (complexus  minor,  i  i,  fig.  107)  may  be  regarded  as  another 
accessory  muscle  to  the  longissimus  dorsi,  which  it  continues  up  to  the  head.  In  order 
to  expose  its  origin,  the  transversalis  colli  must  be  reflected  outward  (as  in  fig.  107). 
It  arises  from  the  angles  between  the  transverse  and  articular  processes  of  the  four  in- 
ferior cervical  vertebrae,  by  four  small  tendons,  or  sometimes  by  a  continuous  aponeu- 
rotic plane.  From  thence  the  fibres  proceed  upward,  and  form  a  small  muscle,  which  is 
inserted  into  the  mastoid  process,  in  a  small  furrow  to  the  inside  of  the  digastric  groove. 
This  small  muscle  is  almost  always  interrupted  by  a  tendinous  intersection  near  its 
mastoid  insertion. 

The  cervical  portion  of  the  transverso-spinalis.*  While  the  preceding  muscles  present 
only  a  few  fasciculi  in  the  neck,  the  transverso-spinalist  undergoes  an  enlargement  in 
this  region,  so  as  to  occupy  the  entire  cervical  groove  (a  and  b,fig.  108).  In  camivora, 
this  portion  of  the  muscle  is  enormously  developed  (much  more  so  than  in  man),  in  con- 
sequence of  those  animals  using  the  head  and  neck  in  seizing  or  struggling  with  prey. 
In  mammalia,  as  in  man,  the  dorsal  portion  of  the  transverso-spinalis  is,  as  it  were,  but 
a  rudiment  in  the  lumbo-sacral  region ;  the  muscle  is  larger  in  man  than  in  other  animals, 
on  account  of  his  erect  posture.  Albinus  described  the  enlarged  cervical  portion  as  a 
separate  muscle,  viz.,  the  spinalis  cervicis. 

In  the  neck,  as  in  the  other  regions,  the  transverso-spinalis  is  a  collection  of  super- 
imposed fasciculi,  which  arise  from  the  transverse  processes  of  the  five  or  six  upper 
dorsal,  and  from  the  articular  processes  of  the  five  lower  cervical  vertebrae,  and  are  in- 
serted into  the  spinous  processes  of  the  six  lower  cervical  vertebrae  :  the  highest  and  the 
largest  fasciculus  is  attached  to  the  axis.  This  muscle,  which  would  have  been  much 
better  named  articvio-spinalis,  is  composed  of  several  layers  of  fasciculi,  placed  one  above 
the  other,  and  extending  from  the  whole  length  of  the  articular  processes  and  laminae 
of  the  vertebrae  below  to  the  whole  length  of  the  spinous  processes  and  laminae  of  the 
vertebrae  above.  The  length  of  these  layers  diminishes  progressively  from  the  more 
superficial  {a,  fig.  108)  to  the  deep-seated  ones  (6) ;  the  latter  extend  only  from  one  ver- 
tebral lamina  to  another,  and  might  be  considered  as  proper  muscles  of  the  laminae,  and 
not  as  a  part  of  the  transverso-spinalis  muscle.  The  most  superficial  layer  is  composed 
of  radiating  fasciculi,  diverging  from  one  articular  process  to  the  summits  of  several  of 
the  spinous  processes. 

The  Complexus. 

Dissection. — ^Divide  the  splenius  perpendicularly  to  the  direction  of  its  fibres,  and  re- 
flect the  two  parts  upward  and  downward  ;  turn  outward  the  upper  portions  of  the  lon- 
gissimus dorsi,  the  transversalis  colli,  and  the  trachelo-mastoid  {see  fig.  107). 

The  complexus  {I,  fig.  107)  is  situated  beneath  the  splenius  at  the  posterior  part  of  the 
neck  and  upper  part  of  the  back.  It  is  a  flat  muscle,  broad  above,  but  terminating  in  a 
point  below. 

Attachments. — It  arises,  1.  From  the  transverse  processes  of  the  five  or  six  superior 

*  If  we  were  to  follow  the  order  of  super-imposition  rigorously,  the  complexus  should  be  described  before 
this  muscle,  which  cannot  be  brought  into  view  until  the  former  is  removed. 

t  [This  portion  of  the  transverso-spinalis  corresponds  to  the  semi-spinalis  colli  (a,  fig.  108),  and  the  cervj 
cal  fasciculi  (6)  of  the  niultifidus  spins  of  Albinus.  1 


206  MYOLOGY. 

dorsal  vertebrae  ;  2.  From  the  articular  tubercles  and  the  angular  depression  formed  be- 
tween them  and  the  transverse  processes  of  the  four  inferior  cervical  vertebrae  ;  3.  Some- 
times from  the  spinous  processes  of  the  seventh  cervical  and  two  upper  dorsal  vertebrae  : 
it  is  inserted  upon  the  side  of  the  external  occipitd  crest  into  the  inner  half  of  the  rough 
space  comprised  between  the  two  semicircular  lines.  The  origins  of  this  muscle  con- 
sist of  tendons,  from  which  the  inferior  fleshy  fibres  pass  vertically  upward,  the  superior 
ones  obliquely  inward  and  upward,  becoming  graduaUy  shorter  and  more  nearly  horizon- 
tal. The  muscular  fibres  are  interrupted  by  some  very  remarkable  tendinous  intersec- 
tions. Thus,  on  the  inside,  the  fleshy  fasciculus  arising  from  the  sixth,  fifth,  and  fourth 
dorsal  vertebrae,  gives  origin  to  a  tendon,  which  proceeds  along  the  inner  edge  of  the 
muscle,  and,  at  the  distance  of  an  inch  and  a  half  or  two  inches,  becomes  the  origin  of 
another  fleshy  fasciculus,  which  is  attached  to  the  side  of  the  occipital  crest ;  hence  the 
name  of  biventer  cervicis,  given  by  Eustachius  to  the  whole  complexus,  and  by  Albinus  to 
this  inner  portion  only  (m,  fig.  107).  More  externally,  there  is  another  flat  tendon  ex- 
tending along  the  posterior  surface  of  the  muscle,  from  the  outer  edge  of  which  an  apo- 
neurotic intersection  passes  in  a  zigzag  course  obliquely  outward  and  upward.  It  is  not 
uncommon  to  find  another  small  digastric  fasciculus  with  a  separate  tendon,  on  the  an- 
terior surface  of  the  muscle. 

Relations. — The  complexus  is  covered  by  the  trapezius,  splenius,  longissimus  dorsi, 
transversalis  colli,  and  trachelo-mastoid,  and  covers  the  transverso-spinalis  and  the  recti 
and  obliqui  capitis.  Its  inner  edge  is  separated  from  the  muscle  of  the  opposite  side  by 
a  considerable  quantity  of  adipose  tissue,  and  by  a  prolongation  of  the  ligamentum  nuchae. 

The  Inter-spinales  Colli. 

The  inter-spinales  muscles  are  distinct  in  the  neck  oidy.  It  is  generally  admitted  that 
there  are  five  pairs,  the  first  of  which  extends  between  the  axis  and  the  third  cervical 
vertebra,  and  the  last  between  the  seventh  cervical  and  first  dorsal  vertebras.  They  are 
small  quadilateral  muscles,  extending  from  one  of  the  borders  of  the  groove  in  the  spinous 
process  below  to  the  corresponding  lip  of  the  next  process  above.  Externally,  they  are 
in  relation  with  the  transverso-spinalis,  and  are  separated  from  each  other  internally  by 
cellular  tissue  and  an  aponeurotic  lamina. 

Fig.  108.  The  Recti  Capitis  Posticiy  Major  and  Minor. 

The  rectus  capitis  posticus  major  {e,fi^.  108)  may  be  regarded  as  an 
axoido-occipital,  and  the  rectus  minor  (d)  as  an  atloido-occipital  inter-spi- 
ndis  muscle.  They  both  arise  tendinous,  the  smaller  from  the  tubercle 
on  the  posterior  arch  of  the  atlas,  and  the  greater  from  the  superior 
tubercle  of  the  spinous  process  of  the  axis  (2) ;  and,  increasing  in  size, 
they  both  pass  obliquely  upward  and  outward.  The  rectus  major, 
^h  which  is  much  the  larger  and  more  oblique,  is  inserted  to  the  outer 
side  of  the  inequalities  situated  below  the  inferior  semicircular  line 
of  the  occipital  bone ;  the  rectus  minor  is  inserted  to  their  inner  side. 
The  name  of  recti  is  not,  therefore,  very  appropriate,  for  both  of  them 
(but  more  especially  the  larger  one)  are  directed  obliquely  ;  but  they 
are  so  called  in  contradistinction  to  two  neighbouring  muscles  which 
are  much  more  oblique.  The  obliquity  of  these  muscles  (by  increas- 
ing their  length)  allows  of  more  extended  movements,  and,  at  the 
same  time,  enables  them  to  assist  in  rotating  the  head. 

Tht  Ohliquus  Capitis  Major  or  Inferior^  and  Obliquus  Minor  or  Superior. 

The  ohliquus  major  or  inferior  (/,  fig.  108),  as  far  as  its  insertions  are  concerned,  may 
be  called  the  axoido-atloid  spino-transversalis  ;  it  resembles,  in  fact,  a  thick  fasciculus  of 
the  longissimus  dorsi.  The  obliquus  minor  or  superior  {g)  may,  for  the  same  reason,  be 
called  the  atloido-occipital  transverso-spinalis,  resembling  a  thick  fasciculus  of  that  mus- 
cle. The  ohliquus  major  arises  from  the  apex  of  the  spinous  process  of  the  axis,  on  the 
outer  side  of  the  rectus  major  (c),  and  above  the  transverso-spinalis  (i.  c,  the  semi-spi- 
nalis  colli  and  multifidus  spinas  conjoined,  a  and  h) ;  it  forms  a  thick,  cyhndriccd  bundle, 
passes  almost  horizontally  outward,  and  is  inserted  behind  and  below  the  transverse 
process  of  the  atlas,  which  is  excavated  for  this  purpose.  It  is  the  axoido-atloideus  of 
Chaussier.  The  ohliquus  minor  (atloido-sub-mastoideus)  arises  by  some  very  long  tendi- 
nous fibres  from  the  upper  part  of  the  transverse  process  of  the  atlas,  proceeds  at  an 
angle  of  about  45°  towards  the  occipital  bone,  into  which  it  is  inserted  not  far  from  the 
mastoid  process,  by  some  tendinous  fibres,  less  distinctly  marked  than  those  of  its  origin. 

From  this  difference  of  direction,  it  follows  that  the  rectus  major  and  the  two  obliqui 
form  on  each  side  an  equilateral  triangle ;  in  the  interval  between  the  two  triangles  a 
considerable  part  of  the  recti  minores  is  seen. 

Relations. — The  recti  and  obliqui  capitis  are  covered  behind  by  the  complexus,  from 
which  they  are  separated  by  a  very  strong  aponeurotic  lamina  and  much  cellular  tissue ; 


THE    POSTERIOR   SPINAL    MUSCLES.  20T 

they  cover  tlie  posterior  arch  of  the  atlas,  with  the  posterior  ligaments  of  the  atloido-oc- 
cipital  and  atloido-axoid  articulations. 

General  View  of  the  Posterior  Spinal  Muscles. 

After  the  preceding  description,  it  will  now  be  easy  to  comprehend  the  general  guiding 
principles  in  the  arrangement  of  the  innumerable,  and,  at  first  sight,  inextricable  fasci- 
cuh  which  constitute  the  fleshy  mass  known  by  the  general  name  of  the  posterior  spinal 
muscles.  We  shall  first  recall  to  mind,  that  the  levers  to  which  all  these  muscles  are 
ultimately  attached  are,  1.  The  row  of  spinous  processes ;  2.  The  row  of  articular  pro- 
cesses ;  and,  3.  The  row  formed  by  the  transverse  processes  and  the  ribs,  which,  for 
many  reasons,  may  be  regarded  as  extensions  of  those  processes. 

We  shall  suppose  these  three  series  of  levers,  and  therefore  the  several  points  of  in- 
sertion, to  be  represented  by  three  vertical  lines. 

We  must  remember,  also,  that  the  dorsal  transverse  processes  are  upon  the  same  line 
as  the  lumbar  and  cervical  articular  processes,  and  that  the  ribs  are  upon  the  same  line 
as  the  lumbar  transverse  processes  and  the  anterior  roots  of  the  cervical  transverse  pro- 
cesses. (See  Osteology,  p.  5.)  These  data  being  admitted,  we  can  now  reduce  all 
the  posterior  spinal  muscles  into  the  four  following  orders  of  fasciculi,  two  being  vertical 
and  two  oblique. 

1.  The  internal  vertical  or  spinous  muscles,  comprising  the  spinalis  dorsi  (i.  e.,  the  in- 
ternal and  superficial  portion  of  the  longissimus  dorsi),  the  inter-spinalis  of  the  neck,  and 
the  recti  postici  of  the  head.  2.  The  external  vertical  lateral,  or  transverse  muscles,  con- 
nected with  the  transverse  or  costiform  processes.  They  comprise  the  sacro-lumbalis 
and  the  inter-transversales,  among  which  the  quadratus  lumborum  may  be  included.  3. 
The  spino-transverse  and  spino-articular*  oblique  muscles,  including  the  longissimus  dorsi, 
with  its  accessories,  the  transversalis  colli  and  trachelo-mastoid,  the  splenius  and  th6 
obliquus  major.  4.  The  transverso-spinous  and  articulo- spinous*  oblique  muscles,  viz., 
the  transverso-spinalis,  the  complexus,  and  the  obliquus  capitis  minor. 

Action  of  the  Posterior  Spinal  Muscles. 
Having  once  established  the  general  principles  according  to  which  the  posterior  spinal 
muscles  are  arranged,  it  is  very  easy  to  determine  the  mode  of  action  of  each,  and  to  re- 
duce to  very  simple  elements  a  mechanism  to  all  appearance  so  complicated. 

1.  The  long  and  short  spinous  fasciculi  being  vertical,  directly  extend  the  vertebrcil 
column ;  such  is  the  action  of  the  spinalis  dorsi  and  inter-spinalis  colli ;  the  recti  capitis, 
at  the  same  time  that  they  extend  the  head,  rotate  it  also  to  the  side  on  which  the  mus- 
cles are  acting.  When  the  recti  muscles  of  both  sides  act  simultaneously,  the  head  is 
drawn  directly  backward. 

2.  The  fasciculi  of  the  sacro-lumbalis  being  vertical  and  lateral,  erect  the  vertebral 
column,  and  incline  it  to  one  side,  when  only  one  set  of  muscles  acts ;  when  both  sets 
act  together,  they  extend  it  directly  backward. 

3.  As  the  fasciculi  of  the  longissimus  dorsi,  belonging  to  the  spino-transverse  and  spi- 
no-articular group,  have  their  fulcra  upon  the  spine,  and  are  inserted  into  the  articular 
and  the  transverse  processes  or  ribs,  they  conspire  in  erecting  the  vertebral  column,  and 
keeping  it  in  that  position.  But,  from  their  obUquity,  they  produce  a  slight  movement  of 
rotation,  those  fibres  which  are  attached  to  the  articular  processes  having  less  effect  than 
those  connected  with  the  transverse  processes.  In  this  movement,  the  front  of  the  body 
is  turned  to  the  side  on  which  the  muscles  are  situated.  When  the  muscles  of  both 
sides  act  together,  the  spine  is  extended  directly  backward.  The  splenius,  which  is  the 
representative  of  the  longissimus  dorsi  for  the  neck  and  head,  acts  in  the  same  way,  but 
with  greater  effect.  Thus,  by  the  contraction  of  the  left  splenius,  the  face  is  turned  to 
the  left  side,  and  the  head  is  drawn  backward  and  to  the  right  side.  The  obliquus  infe- 
rior jilso  acts  in  the  sEune  direction.  When  the  two  splenii  and  the  two  inferior  oblique 
act  together,  the  head  is  inclined  directly  backward. 

4.  The  fixed  insertions  of  the  transverso-spinalis  being  at  the  articular  or  transverse 
processes,  and  their  movable  points  at  the  spinous  processes,  besides  the  common  effect 
of  erecting  the  vertebral  column,  they  are  also  able  to  rotate  it,  so  that  the  anterior  re- 
gion of  the  trunk  is  turned  to  the  opposite  side.  From  its  obliquity,  this  muscle  is  the 
principal  rotator  of  the  vertebral  column.  The  complexus,  which  is  its  representative 
in  the  neck,  acts  upon  the  head  in  the  same  manner,  but  in  a  more  remarkable  degree. 
Thus,  by  the  contraction  of  the  complexus  of  the  left  side,  the  face  is  turned  to  the  right 
side,  and  the  head  is  inclined  backward  upon  the  left  side,  so  that,  in  rotation,  it  acts  in 
a  precisely  opposite  direction  to  the  splenius.  When  all  these  muscles  act  together,  the 
trunk  is  simply  drawn  erect.  The  superior  oblique  assists  the  complexus  in  the  move- 
ments of  the  head. 

Lastly,  we  may  now  understand  the  successive  actions  which  take  place  along  the 

*  [The  terms  spino-transverse  and  spino-articular  are  applied  to  fasciculi  passing  upward  from  the  spinous 
to  the  transverse  and  articular  processes  ;  transverso-spinous  and  articulo-spiuous,  to  such  as  proceed  upward 
from  the  transverse  and  articular  to  the  spinous  processes.] 


208 


MYOLOGY. 


whole  extent  of  the  posterior  spinal  muscles.  The  sacrum  and  the  iliac  bones  furnish  a 
fulcrum  for  the  fasciculi  which  move  the  lumbar  region  :  this  latter  being  fixed,  then  be- 
comes the  fulcrum  for  those  that  move  the  dorsal  region,  and  so  on  to  the  head,  which 
alone  has  independent  muscles.  It  is  impossible  to  extend  backward  the  dorsal  region, 
and  the  lower  part  of  the  cervical,  without  at  the  same  time  erecting  the  lumbar  region; 
but  the  head  may  be  moved  at  will,  independently  of  the  vertebral  column. 

The  posterior  spinal  muscles  maintain  in  equilibrium  the  weight  of  the  whole  trunk ; 
hence  the  lassitude  experienced  in  the  back,  but  especially  in  the  loins,  by  long-contin- 
ued standing,  walking,  or  even  sitting  without  a  support  to  the  back  ;  and  hence  the  re- 
lief afforded  by  the  recumbent  posture. 

Rotation,  we  have  seen,  scarcely  exists  in  the  loins,  the  back,  or  the  lower  part  of  the 
neck ;  but  at  the  upper  part  of  the  neck  it  is  very  extensive,  and  here  the  rotator  mus- 
cles are  proportionally  strong,  and  directed  very  obliquely. 


MUSCLES  OF  THE  ANTERIOR  ABDOMINAL  REGION. 

The  Obliquus  Externus  Abdominis. — Obliquus  Internus  and  Cremaster. — Transversalis  Ab- 
dominis .  — Rectus  Abdominis.  — Pyramidalis . 

The  muscles  of  the  anterior  abdominal  region  are,  the  external  oblique,  the  internal 
oblique,  the  transversalis,  the  rectus,  and,  occasionally,  the  pyramidalis ;  being  ten  in  the 
whole,  five  on  each  side. 

The  Obliquus  Externus  Abdominis. 

Dissection. — 1.  Make  an  incision  through  the  skin  of  the  abdomen  extending  from  the 
cartilage  of  the  eighth  rib  obliquely  downward  and  inward,  dividing,  at  the  same  time, 
the  very  firm  layer  of  cellular  tissue  which  immediately  covers  the  muscle.  2.  During 
the  preparation  of  this,  as  well  as  2ill  the  other  abdominal  muscles,  place  a  block  under 
the  loins,  and  in  the  dissection  follow  exactly  the  direction  of  the  muscular  fibres. 
The  great  or  external  oblique  muscle  of  the  abdomen  {o,fig.  106,  and  a,  fig.  109),  so  call- 
ed from  the  direction  of  its  fibres  (ob- 
liquus descendens),  forms  the  most  su- 
perficial muscular  layer  of  the  abdom- 
inal parietes,  on  the  sides  and  front  of 
which  it  is  situated :  it  is  very  broad, 
quadrilateral,  and  curved  upon  itself. 

Attachments. — It  arises  from  the  ex- 
ternal surfaces  and  lower  borders  of 
the  seven  or  eight  inferior  ribs,  and  is 
inserted  into  the  anterior  half  of  the  ex- 
ternal lip  of  the  crest  of  the  ilium,  into 
the  external  edge  of  the  anterior  ab- 
dominal aponeurosis,  and  by  it  into  the 
linea  alba.  The  upper  or  costal  attach- 
ments consist  of  seven  or  eight  angu- 
lar tongues,  or  digitations,  fleshy  and 
tendinous  in  their  structure,  and  arran- 
ged in  an  oblique  line,  running  down- 
ward and  backward. 

These  digitations  increase  in  size 
from  above  downward,  as  far  as  the 
eighth  rib,  and  then  diminish  to  the 
twelfth.  The  four  or  five  superior  di- 
gitations are  interposed,  like  the  fingers 
of  the  two  hands  (whence  the  name), 
between  similar  prolongations  of  the 
serratus  magnus.  The  three  or  foui 
lower  digitations  between  those  of  the 
latissimus  dorsi,  by  which  they  are 
covered.  This  series  of  costal  attach- 
ments constituting  the  upper  edge  of 
the  muscle,  represents  a  serrated  curv- 
ed line,  the  convexity  of  which  is  di- 
rected upward  and  backward. 

The  first  digitation  is  attached  close 
to  the  cartilage  of  the  corresponding 
rib,  the  succeeding  ones  are  farther 
and  farther  removed  from  the  first,  and  the  last  is  inserted  into  the  apex  of  the  cartilage 
of  the  last  rib. 


THE    OBLiaUUS    INTEENUS. 


20d 


From  these  attachments  the  fleshy  fibres  proceed  in  different  directions :  the  poste- 
rior pass  nearly  vertically  downward,  the  middle  obliquely  downward  and  inward,  and 
the  upper  almost  horizontally  inward  ;  the  posterior  terminate  by  short  tendinous  fibres 
at  the  crest  of  the  ilium ;  the  anterior  at  the  external  concave  edge  of  a  broad  aponeu- 
rosis, which  forms  the  superficial  layer  of  the  anterior  abdominal  aponeurosis,  and,  by 
interlacing  with  the  corresponding  structure  of  the  opposite  side,  concurs  in  forming  the 
linea  alba,  and  is  folded  upon  itself  below,  to  form  the  crural  arch,  or  Poupart's  ligament. 
(See  Aponeurolggy.) 

It  should  be  remarked,  that  the  fibres  of  the  external  oblique  follow  exactly  the  me 
direction  as  those  of  the  external  intercostal  muscles. 

Relations. — The  external  oblique  is  covered  by  the  skin,  a  considerable  quantity  o* 
adipose  tissue,  and  behind  by  a  small  portion  of  the  latissimus  dorsi.  It  covers  the  in- 
ternal oblique,  the  anterior  extremities,  and  the  cartilages  of  the  seven  or  eight  inferior 
rib's,  together  with  the  corresponding  external  intercostal  muscles.  The  most  remark- 
able relation  is  that  of  its  posterior  border  with  the  outer  edge  of  the  latissimus  dorsi. 
Most  commonly  this  border  is  covered  by  the  latissimus  dorsi ;  but  sometimes  a  trian- 
gular space  exists  between  them,  which  has  been  much  noticed  since  Petit  described  a 
hernial  protrusion  in  it,  which  he  called  lumbar  hernia. 

Action. — The  external  oblique  performs  a  threefold  action:  1.  It  compresses  the  ab- 
dominal viscera  during  any  exertion,  or  in  expulsion  of  the  faeces,  in  labour,  &c. ;  2.  It 
depresses  the  ribs,  and  thus  indirectly  flexes  the  vertebral  column  ;  3.  From  its  obliquity, 
it  rotates  the  vertebral  column,  through  the  medium  of  the  ribs,  so  that  the  fore  part  of 
the  trunk  is  turned  to  the  opposite  side.  When  the  two  muscles  act  together,  the  tho- 
rax is  inclined  directly  forward.  Hitherto  we  have  supposed  that  the  movable  point  of 
the  muscle  is  at  the  ribs  ;  if,  on  the  contrary,  the  thorax  be  fixed,  it  then  draws  the  pel- 
vis upward,  and  rotates  the  vertebral  column,  so  that  the  fore  part  of  the  pelvis  is  turn- 
ed to  the  same  side  as  the  contracting  muscle. 

The  Obliquus  Internus,  and  the  Cremaster. 

Dissection. — Divide  the  external  oblique  across  the  direction  of  its  fibres,  i.  e.,  down- 
ward and  backward. 

The  small  or  internal  oblique  of  the  abdomen  (obliquus  ascendens,  p,Jig:  106,  and  a,  Jig. 
110)  is  a  broad,  irregularly-quadrilateral  mus-  Fig.llO. 

cle,  much  broader  in  front  than  behind,  and 
smaller  and  thinner  than  the  preceding.  It 
occupies  the  anterior,  lateral,  and  posterior 
parts  of  the  abdomen. 

Attachments. — It  arises  from  the  spinous 
processes  of  the  lumbar  vertebrae,  from  the 
anterior  three  fourths  of  the  interval  between 
the  borders  of  the  iliac  crest,  and  from  the 
crural  arch  (Poupart's  ligaments).  It  is  in- 
serted into  the  lower  edges  of  the  cartilages 
of  the  ninth,  tenth,  eleventh,  and  twelfth  ribs, 
and  into  the  linea  alba  by  means  of  the  mid- 
dle layer  of  the  anterior  abdominal  aponeu- 
rosis. The  spinal  fibres  take  their  origin 
through  the  medium  of  the  posterior  abdomi- 
nal aponeurosis  :  they  are  few  in  nmnber. 
The  iliac  portion  of  them  arise  by  very  short 
tendinous  fibres,  and  those  which  proceed 
from  the  crural  arch  arise  from  the  sort  of 
groove  situated  on  its  upper  surface.  From 
this  threefold  origin  the  fibres  proceed  in  dif- 
ferent directions  :  the  posterior  almost  verti- 
cally upward ;  those  which  arise  from  the 
crest  of  the  ilium  obliquely  upward  and  in- 
ward, becoming  longer  and  more  oblique  an- 
teriorly ;  those  which  proceed  from  near  the 
anterior  superior  spinous  process  of  the  ilium 
are  horizontal ;  and,  lastly,  those  which  arise 
from  the  crural  arch  pass  obliquely  downward 
and  inward.  The  posterior  fibres  terminate 
at  the  lower  edge  of  the  cartilages  of  the  four 
inferior  ribs,  and  are  continuous  with  the  in- 
ternal intercostal  muscles,  in  the  intervals 
between  the  tenth  and  eleventh  and  eleventh  and  twelfth  ribs,  indicating  the  analogy 
between  these  muscles.  I  have  often  observed  the  insertion  into  the  last  rib  to  be 
wanting.     The  middle  fibres,  which  are  the  most  numerous,  terminate  at  the  external 

Dd 


210  MYOLOGY. 

edge  of  the  middle  layer  of  the  anterior  abdominal  aponeurosis.  The  fibres  arising  from 
the  crural  arch  are  few  in  number,  pale,  and  fasciculated ;  some  terminate  at  the  pubes, 
passing  behind  the  inguinal  or  external  abdominal  ring ;  others  proceeding  from  the 
ring,  in  the  male,  form  the  cremaster  muscle. 

Relations. — It  is  covered  by  the  external  oblique,  and  behind  by  a  small  portion  of  the 
latissimus  dorsi ;  and  it  lies  superficially  to  the  transversalis.  The  most  important  re- 
lations are  those  of  its  inferior  edge  with  the  inguinal  ring  of  the  external  oblique,  which 
it  partly  closes  on  the  inner  side,  as  Scarpa  and  Bichat  have  well  pointed  out,  and  with 
the  spermatic  cord,  which  passes  beneath  it,  and,  during  the  descent  of  the  testicle, 
draws  with  it  some  of  the  lower  fibres  of  the  muscles  ;  and  hence  the  looped  arrange- 
ment they  assume. 

The  cremaster.  The  loops  so  well  described  by  M.  Jules  Cloquet  are  very  variable, 
and  do  not  always  appear  to  me  to  constitute  the  entire  muscle.  According  to  this 
anatomist,  the  cremaster  is  nothing  more  than  the  lower  fibres  of  the  internal  oblique, 
that  had  been  entangled  with  the  testicle  during  its  descent,  forming  loops  in  front  of  the 
cord,  the  concavity  of  which  is  directed  upward,  and  which  may  be  traced  to  the  bottom 
of  the  scrotum.  But  I  have  often  been  convinced,  from  the  examination  of  subjects  in 
which  the  cremaster  was  much  developed,  that  this  muscle  {b,  Jigs.  109,  137)  consists 
principally  of  a  longitudinal  fasciculus,  partly  derived,  it  is  true,  from  the  lower  fibres  of 
the  internal  oblique,  but  consisting  partly,  also,  of  proper  fibres  arising  from  the  crural 
arch,  near  the  external  pillar  of  the  ring  ;  and  that  this  fasciculus  is  lost  upon  the  proper 
sheath  of  the  cord,  to  which  it  is  intimately  united.  The  oflSce  of  this  muscle  is  to 
raise  the  entire  testicle.  The  slow  vermicular  motion  observed  in  the  scrotum  during 
the  venereal  orgasm,  or  from  the  action  of  cold,  is  not  at  all  connected  with  it. 

The  actions  of  the  internal  oblique  are,  1.  Compression  of  the  abdominal  viscera;  2. 
Depression  of  the  ribs,  and,  consequently,  flexion  of  the  trunk  ;  3.  Rotation  of  the  trunk, 
so  that  the  fore  part  of  the  body  is  turned  to  the  same  side.  The  right  internal  oblique, 
therefore,  co-operates  with  the  left  external  oblique ;  when  it  acts  with  its  fellow,  the 
thorax  is  drawn  directly  towards  the  pelvis  ;  but  if  the  chest  is  fijced,  they  move  the  pel- 
vis upon  the  loins. 

The  Transversalis  Abdominis. 

Dissection. — 1.  Make  a  horizontal  section  of  the  internal  oblique  ;  2.  Dissect  with  care 
the  two  flaps  of  this  nmscle,  following  the  direction  of  the  fibres  of  the  transversalis  ;  3. 
In  order  to  obtain  a  good  view  of  the  costal  attachments,  open  the  abdomen  and  exam- 
ine them  on  the  inner  surface  of  the  ribs  ;  this  may  be  omitted  until  the  diaphragm  is  to 
be  inspected. 

The  transversalis  abdominis,  so  named  from  the  direction  of  its  fibres,  is  situated  more 
deeply  than  the  two  preceding  muscles,  and,  like  them,  is  irregularly  quadrilateral  (b,  fig. 
110). 

Attachments. — It  arises  from  the  six  lower  ribs,  from  the  anterior  three  fourths  of  the 
internal  lip  of  the  crest  of  the  ilium,  and  from  the  spinous  and  transverse  processes  of 
the  lumbar  vertebrae.  It  is  inserted  into  the  linea  alba  by  means  of  the  deep  layer  of 
the  anterior  abdominal  aponeurosis.  The  costal  attachments  consist  of  fleshy  digita- 
tions  interposed  between  those  of  the  diaphragm,  the  two  muscles  being  actually  contin- 
uous at  the  two  inferior  intercostal  spaces  ;  the  vertebral  attachments  are  efiected  by 
means  of  the  posterior  abdominal  aponeurosis ;  and  from  the  ilium  it  arises  by  very 
short  tendinous  fibres  internally  to  the  small  obliqije.  From  these  three  origins  the  fleshy 
fibres  proceed  parallel  to  each  other  and  horizontally  inward  ;  the  lower  ones  alone  are 
slightly  inclined  downward  and  inward  ;  the  middle  fibres  are  the  longest.  They  are  all 
inserted  into  the  external  convex  edge  of  a  tendinous  expansion,  which  constitutes  the 
posterior  layer  of  the  anterior  abdominal  aponeurosis. 

Relations. — The  transversalis  is  covered  by  the  internal  oblique,  and  rests  upon  the 
peritoneum,  from  which  it  is  separated  by  a  fibrous  lamina,  which  is  very  distinct  in 
front,  where  it  is  named  the  fascia  transversalis. 

Actions. — 1.  It  acts  more  powerfully  upon  the  abdominal  viscera  than  any  of  the  pre- 
ceding muscles,  compressing  them  strongly,  like  a  girth,  against  the  vertebral  column, 
and  assisting  greatly  in  the  process  of  defecation.  2.  It  draws  inward  the  rib  to  which 
it  is  attached,  and  thus  materially  assists  in  expiration. 

The  Rectus  Abdominis. 

Dissection. — 1.  The  subject  being  laid  upon  its  back,  place  a  block  under  the  loins  ;  2. 

After  having  removed  the  skin,  make  a  vertical  incision  through  the  strong  aponeurosis, 

at  about  two  fingers'  breadth  from  the  linea  alba ;  3.  Dissect  off  the  two  flaps  inward  and 

:  outward.    The  adhesions  between  this  aponeurosis  and  the  muscle  are,  however,  so  in- 

'timate  at  many  points,  that  it  is  impossible  to  separate  them. 

The  rectus  abdominis  (c,  fig.  110)  is  situated  at  the  anterior  and  middle  part  of  the  ab- 
domen on  each  side  of  the  linea  alba,  and  occupies  the  sp.^ce  between  the  pubes  and  the 
.  cartilage  of  the  fifth  rib.     It  is  flattened  like  a  riband  in  front  and  behind  ;  it  is  about 


THE   RECTUS    ABDOMINIS. 

three  or  four  fingers'  breadth  wide  above,  and  only  two  below.  Its  breadth  is  generally 
in  an  inverse  proportion  to  its  thickness. 

Attdchmcnts. — It  arises  from  the  upper  edge  of  the  os  pubis,  in  the  space  between  the 
spine  and  the  symphysis  ;  and  is  inserted  in  front  of  and  below  the  cartilage  of  the  sev- 
enth rib  and  costo-xiphoid  ligament,  to  the  cartilages  of  the  fifth  and  sixth  ribs,  and 
sometimes  to  the  bone  also. 

The  pubic  attachment  is  a  flat  tendon,  consisting  of  two  very  distinct  portions,  of 
which  the  external  is  the  larger.  This  tendon  is  continuous  by  its  external  border  Avith 
the  fascia  transversalis.  It  is  separated  from  its  fellow  of  the  opposite  side  by  a  very 
narrow  and  thick  fibrous  septum,  which  forms  the  lower  part  of  the  linea  alba.  Some- 
times the  internal  tendinous  fibres  intersect  with  those  of  the  opposite  side  in  front  of 
the  symphysis  pubes  ;  and  some  fleshy  fibres  often  arise  from  the  sides  of  the  linea  alba. 
The  presence  or  absence  of  the  pyramidalis  affects  the  size  of  the  lower  part  of  this 
muscle.  From  this  tendinous  origin  the  fleshy  fibres  proceed  vertically  upward  (whence 
the  name  oi  rectus).  At  the  upper  part,  where  they  are  prolonged  in  an  expanded  form 
upon  the  thorax,  they  are  slightly  oblique  from  within  outv^ard,  and  divided  into  three 
unequal  portions  :  the  internal,  the  smallest,  is  attached  to  the  cartilage  of  the  seventh 
rib  and  to  the  costo-xiphoid  ligament ;  the  middle,  which  is  larger,  is  fixed  to  the  carti- 
lage of  the  sixth  rib  ;  and  the  external,  by  far  the  largest,  to  the  cartilage  of  the  fifth  rib. 
Very  often  a  small  portion  of  the  muscle  is  insertad  into  the  base  and  edges  of  the  xi- 
phoid cartilage,  thus  justifying  the  name  of  stemo-puhien  given  to  it  by  Chaussier.  It  is 
not  uncommon  to  find  this  muscle  give  off  a  fourth  bundle  to  the  fourth  rib,  and  even  an 
aponeurotic  expansion  to  the  sterno-cleido-mastoid.  The  rectus  is  interrupted  by  two, 
three,  four,  or  five  tendinous  intersections,  which  pass  transversely  or  obUquely  across  the 
muscle  in  a  flexuous  or  zigzag  course,  seldom  occupying  either  the  entire  thickness  or 
width  of  the  muscle,  which  they  divide  into  so  many  smaller  muscles.  There  are  always 
more  intersections  above  than  below  the  umbilicus. 

Relations. — This  muscle  is  contained  in  a  very  strong  tendinous  sheath,  which  is  form- 
ed by  the  anterior  abdominal  aponeurosis,  is  thicker  in  front  than  behind,  much  stronger 
below  than  above,  and  completely  isolates  the  muscle.  Below  and  behind,  this  sheath 
is  deficient,  in  which  situation  the  muscle  (passing  through  the  openings.  Jig.  1 10,  in  the 
aponeurosis  of  the  transversalis)  rests  directly  upon  the  peritoneum ;  the  upper  and  pos- 
terior part  of  the  sheath  is  also  wanting,  so  that  the  muscle  is  in  immediate  contact 
with  the  cartilages  of  the  fifth,  sixth,  seventh,  eighth,  and  ninth  ribs,  and  with  the  cor- 
responding intercostal  muscles.  The  linea  alba  occupies  the  interval  between  the  two 
muscles,  which  is  much  larger  above  than  below  the  umbilicus  ;  but  the  most  important 
of  all  the  relations  of  the  rectus  is  that  of  its  posterior  surface  with  the  epigastric  artery, 
which  we  shall  hereafter  notice. 

Actions. — This  muscle,  having  its  fixed  point  below,  and  its  movable  attachments  di- 
vided between  the  fifth,  sixth,  and  seventh  ribs,  depresses  the  whole  thorax,  and,  con- 
sequently, the  vertebral  column.  Few  muscles  are  so  favourably  situated  as  the  rectus, 
which  both  acts  upon  a  very  long  lever,  and  is  inserted  at  right  angles  to  the  part  to  be 
moved. 

As  the  rectus  forms  a  curve,  the  convexity  of  which  is  directed  forward,  and  cannot 
contract  without  becoming  rectilinear,  it  follows  that  the  first  effect  of  its  contraction  is 
the  compression  of  the  abdominal  viscera;  hence  it  assists  in  expelling  the  contents  of 
the  bladder,  rectum,  and  uterus  ;  it  aids  in  expiration,  by  depressing  the  ribs,  and,  by 
keeping  them  fixed  when  the  thorax  is  dilated,  it  assists  in  the  performance  of  any  ef- 
fort.   \\Tien  the  fixed  point  is  above,  the  rectus  becomes  a  flexor  of  the  pelvis. 

What  are  the  uses  of  the  intersections  1  It  is  generally  stated  that  their  effect  is  to 
increase  the  number  of  fibres,  and  thereby  augment  the  force  of  the  muscle  ;  and  in  sup- 
port of  this  a  principle  is  adduced,  which  is  incontestable  in  itself,  viz.,  that  the  power 
of  a  muscle  is  in  a  direct  ratio  to  the  number  of  its  fibres  ;  for  if  each  fibre  represent  one 
partial  power,  the  more  of  these  the  greater  must  be  the  total  power.  But  it  has  been 
overlooked,  that  this  law  only  applies  to  fibres  arranged  side  by  side,  not  to  those  which 
are  placed  end  to  end.  In  fact,  it  may  be  experimentally  shown  that,  when  two  equal 
forces  are  applied  to  a  lever,  parallel  to  each  other,  they  produce  double  the  effect  either 
would  have  done  separately ;  but  if  one  be  made  continuous  with  the  other,  and  both  are 
then  applied  to  the  same  lever,  they  only  produce  an  effect  equal  to  that  of  either  per  se. 
These  intersections,  therefore,  do  not  increase  the  power  of  the  muscle ;  nor  do  they 
diminish  the  extent  of  motion,  for  the  sum  of  the  contractions  of  the  small  muscles  into 
which  they  divide  the  recti  is  equal  to  that  of  an  undivided  muscle.  What,  then,  are 
the  uses  of  these  intersections  1  Can  it  be  intended,  as  Bertin  has  said,  to  associate 
the  obUque  muscles  with  the  recti  by  means  of  the  intimate  adhesions  existing  between 
.them  and  the  aponeuroses  1* 

*  Benin  considers  these  adhesions  as  true  points  of  attachment  tor  the  muscles  of  the  aiitlomeii,  so  that 
when  the  rectus  contracts,  it  acts  :iot  only  upon  tho  pubes,  but  also  upon  the  crests  of  tlie  ilia,  through  the 
medium  of  the  abdominal  aponeuroses.  Professor  Berard,  who  Irmgs  forward  this  forgotten  opinion  of  Ber- 
tin iRipert.  Gentr.  dcs  Sc.  Med.,  art.  Abdomen),  correctly  observes,  that  tho  obliquus  internus  only  adheres 
to  tho  rectus.  In  the  same  aficle  M.  Biirard  declares  he  is  not  satisfied  that  the  intersections  increMe  the 
,  I  \ver  of  the  recti  muscles. 


SICI^ 


MYOLOGY. 


;,  v'-.r;       wV^jtU-TSia  The  Pyramidalis.     •:^^^^>^.^At.::< 

The  pyramidalis  {d,  fig.  1 10),  a  small  triangular  muscle  which  is  often  deficient,  occu- 
pies the  lower  part  of  the  abdomen  on  each  side  of  the  linea  alba.  It  arises  from  the 
pubis  and  the  anterior  ligament  of  the  symphysis  by  tendinous  fibres,  from  which  the 
fleshy  portion  proceeds  upward,  the  internal  fibres  vertically,  the  external  obliquely  up- 
ward and  inward,  and  terminates  by  a  pointed  extremity,  which  is  attached  to  the  hnea 
alba,  and  forms  the  apex  of  the  muscle,  the  base  being  at  the  os  pubis.  It  is  covered 
by  the  aponeuroses  of  the  obliqui  and  transversalis  muscles,  and  rests  upon  the  rectus. 
The  lower  part  of  the  rectus  and  the  pyramidalis  are  united  together.  When  the  latter 
is  wanting,  the  lower  end  of  the  rectus  is  proportionally  increased  in  size,  and  vice  versa- 
There  are  sometimes  two  pyramidales  on  one  side,  and  one  on  the  other ;  sometimes  the 
two  are  of  unequal  size.  In  a  negro  I  found  them  extending  beyond  the  middle  of  the 
space  between  the  pubis  and  the  umbilicus. 
Action. — It  is  a  tensor  of  the  linea  alba. 


DIAPHRAGMATIC  REGION. 


T^e  Diaphragm. 

Dissection. — Description. — Attachments. — Relations. — Action. 
Dissection. — In  order  to  expose  this  muscle,  it  is  necessary  to  open  the  abdomen  and 
remove  all  the  abdominal  viscera,  taking  great  care  in  detaching  the  liver,  stomach,  and 
Kidneys.     Tie  the  oesophagus  and  vena  cava  where  they  pass  through  the  diaphragm, 
and  cut  them  below  the  ligature.     Raise  the  peritoneum  with  the  fingers  or  forceps,  and 
tear  it  gently  away  ;  thus  exposing  the  lower  surface  of  the  muscle  without  using  the 
scalpel.     All  the  insertions  of  the  diaphragm  are  well  seen  on  this  surface.     In  order  to 
study  the  convex  surface  of  the  muscle,  another  subject  should  be  provided,  and  the  tho- 
rax opened  before  the  abdomen.     This  is  the  only  method  by  which  a  good  idea  of  it  can 
be  obtained ;  for  when  the  abdomen  has  been  previously  opened,  the  muscle  becomes 
relaxed  as  soon  as  the  thorax  is  cut  into,  and  affords  no  idea  of  its  naturally  vaulted  form. 
The  diaphragm  (septum  transversum,  a  a,  fig.  Ill),  which  exists  in  mammalia  only 
p^    jlj  is,  according  to  the  expression  of  Haller,  with  the 

exception  of  the  heart,  the  most  important  muscle. 
I  in  '\    f  f  \U\        of  the  body.     It  is  a  muscular  septum,  sitotticd  ob- 

liquely at  the  junction  of  the  upper  with  the  two 
lower  thirds  of  the  trunk.  It  separates  the  thorax 
-a  from  the  abdomen,  constituting  the  floor  of  the  for- 
mer and  the  roof  of  the  latter.  All  other  muscles 
,^  are  placed  on  the  outside  of,  or  around,  the  levers 
which  they  are  intended  to  move  ;  but  the  diaphragm 
alone  is  situated  within  those  levers,  like  the  mus- 
cles of  animals  having  an  external  skeleton. 

The  diaphragm  divides  the  body  into  two  unequal 
parts :  an  upper,  or  supra-diaphragjnatic ;  and  a  lower, 
or  infra-diaphragmatic.  It  is  placed  on  the  median 
line,  but  is  not  symmetrical.  It  is  elliptical  in  form, 
its  longest  diameter  being  from  side  to  side,  thin  and 
flattened,  and  resembles  an  arch,  or,  rather,  a  fan, 
the  broad  and  circular  portion  of  which  is  horizon- 
tal, while  the  narrow  part  is  vertical,  and  at  right 
angles  to  the  former.  The  older  anatomists,  there- 
fore, divided  it  into  two  portions  :  the  upper,  or  great 
muscle  of  the  diaphragm ;  and  the  lower,  or  small  m)is 
cle  of  the  diaphragm. 

Attachments. — It  arises  partly  from  the  lumbar  re 
gion  of  the  vertebra,  column,  in  front  of  the  bodies  and  intervertebral  substances  of  the 
second,  third,  and  fourth  lumbar  vertebra? ;  partly  from  the  posterior  surface  of  the  ster- 
num and  the  base  of  the  ensiform  cartilage  ;  and  partly  from  the  posterior  surface  and 
upper  edge  of  the  cartilages  and  contiguous  bony  portions  of  the  seventh,  eighth,  ninth, 
tenth,  eleventh,  and  twelfth  ribs.     Sometimes  it  is  attached  also  to  the  sixth  rib. 

The  vertebral  origin  consists  of  two  tendons,  formed  by  several  smaller  vertical  ten- 
dons, situated  in  front  of  each  other,  which  are  blended  with  the  anterior  common  liga- 
ment of  the  spine.  To  these  tendons  two  thick,  fleshy  bundles  succeed,  which  pass  ver- 
tically upward,  become  gradually  thicker  and  broader,  give  off"  a  fasciculus  to  each  other,  • 
and  are  inserted  into  the  posterior  notch  in  the  aponeurosis,  having  the  form  of  a  trefoil 
leaf,  which  forms  the  centre  of  the  muscle,  and  is  therefore  called  the  central  aponeurosis 
of  the  diaphragm  {b,  fig.  1 1 1),  or  cordiform  tendon.  These  two  fleshy  bundles  and  their  ten- 
dons (c  c)  are  named  the  pillars,  crura,  or  appendices  of  the  diaphragm.     The  right  crus 


THE    DIAPHRAGM.  213 

IS  anterior,  larger,  and  descends  lower  down  than  the  left.  Each  pillar  is  occasionally 
divided  into  two  very  distinct  secondary  pillars,  and  the  trace  of  this  division  is  always 
visible  in  the  opening  which  gives  passage  to  the  great  splanchnic  nerve.  The  two  pil- 
lars of  the  diaphragm  leave  between  them  an  interval,  divided  into  two  portions  or  rings 
by  the  fleshy  fasciculi  which  they  mutually  give  to  each  other.  The  communicating  fas- 
ciculus from  the  right  pillar  is  anterior,  and  larger  than  that  from  the  left.  Of  the  two 
openings  (ir  rings  between  the  pillars  of  the  diaphragm,  the  loxcer  or  aortic  {d)  is  parabolic, 
and  gives  passage  to  the  aorta,  the  vena  azygos,  the  thoracic  duct,  and  sometimes,  also. 
to  the  left  great  sympathetic  nerve.  Like  all  orifices  through  which  arteries  pass,  it  is 
aponeurotic  in  its  structure,  being  formed  by  the  tendons  of  the  pillars  of  the  diaphragm 
at  the  sides,  and  above  by  a  fibrous  prolongation  of  those  tendons,  which  arches  over 
and  completes  the  ring :  the  upper  or  (Esophageal  opening  (e)  gives  passage  to  the  oesoph- 
agus and  the  pneumo-gastric  nerves;  it  is  elliptical,  and  altogether  muscular.  In  one 
subject,  however,  I  found  the  upper  part  tendinous ;  and  in  another,  a  small  muscular 
fasciculus  proceeded  from  the  edge  of  the  orifice,  and  was  lost  upon  the  coats  of  the 
oesophagus.     Haller  has  twice  observed  the  same  peculiarity. 

A  fibrous  prolongation  proceeds  outward  from  the  tendon  of  each  crus,  and  is  fixed  to 
the  base  of  the  corresponding  transverse  process  of  the  first  lumbar  vertebra,  so  as  to 
form  an  arch  on  each  side  (fig.  Ill),  under  which  the  upper  end  of  the  psoas  muscle  pass- 
es (ligamentum  arcuatum  proprium).  Another  aponeurotic  arch,  which  has  been  improp- 
erly called  ligamentum  arcuatum  {ligament  cintre  du  diaphragme),  for  it  is  nothing  more 
than  the  upper  edge  of  the  anterior  layer  of  the  aponeurosis  of  the  transversalis  muscle 
folded  upon  itself,  extends  from  the  outer  extremity  of  the  preceding  arch  to  the  lower 
border  and  apex  of  the  last  rib  ;  under  it  passes  the  superior  portion  of  the  quadratus 
lumborum  muscle  {fig.  111).  From  both  these  arches  muscular  fibres  pass  forward,  and 
are  inserted  into  the  corresponding  part  of  the  cordiform  tendon.  Indeed,  the  five  ten- 
dinous arches  which  we  have  just  described,  viz.,  the  aortic  in  the  middle,  and  the  two 
on  each  side  for  the  psoas  and  quadratus  lumborum  muscles,  give  origin  to  all  the  fleshy 
fibres  which  terminate  at  the  posterior  notch  of  the  central  tendon  of  the  diaphragm 
The  existence  of  these  arches  led  Haller  and  Scemmering  to  reckon  three  or  four  crura 
on  each  side.  The  cordiform  tendon  in  which  the  preceding  muscular  fibres  are  insert- 
ed serves,  in  its  turn,  as  the  origin  of  other  fibres,  which  constitute  the  vault  of  the  dia 
phragm.  This  central  aponeurosis  (i),  to  which  so  much  importance  was  attached  by 
the  ancients,  under  the  name  of  the  phrenic  centre,  and  which  some  modern  anatomists 
regard  as  the  central  point  of  the  entire  aponeurotic  system  of  the  human  body,  occupies 
the  middle  of  the  vault  of  the  diaphragm,  immediately  below  the  pericardium,  with  which 
its  circiunference  is  blended  in  adults,  but  from  which  it  may  be  easily  separated  in  young 
subjects  :  it  is  a  sort  of  aponeurotic  island,  surrounded  on  all  sides  by  muscular  fibres, 
and  converting  the  diaphragm  into  a  true  digastric  muscle.  In  form,  it  resembles  a  tre- 
foil leaf,  with  a  notch  in  the  situation  of  the  pedicle  ;  each  division  is  called  a  wing  or 
leaflet ;  the  middle  leaflet  is  the  largest,  the  right  the  next,  and  the  left  the  smallest.  Be- 
tween the  right  and  the  middle  le^et  is  an  opening  (/),  sometimes  converted  into  a  ca- 
nal for  the  inferior  vena  cava.  This  orifice  is  entirely  tendinous,  and  of  a  quadrangular 
shape  when  the  vena  cava  is  removed.  It  is  bounded  by  four  tendinous  fasciculi,  which 
meet  at  right  angles.  The  cordiform  tendon  is  itself  composed  of  several  planes  of  fibres ; 
the  principal  of  which  consists  of  a  diverging  series,  running  forward,  and  uniting  into  ir- 
regular, straight,  or  curved  bundles,  which  intersect  each  other  at  various  angles ;  an 
arrangement  that  gives  great  strength  to  the  tendon.  The  fleshy  fibres  are  attached  to 
all  points  of  the  circumference  of  this  tendon,  and  radiate  from  it  in  all  directions.  The 
anterior,  very  short,  and  sometimes  aponeurotic,  proceed  to  the  base  of  the  ensiform  car- 
tilage, describing  a  slight  curve,  with  the  concavity  directed  downward.  A  triangular 
interval,  or  else  several  small  spaces,  are  often  left  between  these  fibres,  establishing  a 
communication  between  the  cellular  tissue  of  the  thorax  and  that  of  the  abdomen. 
Hence,  diaphragmatic  hernias  occasionally  occur ;  and  pus,  formed  in  the  neck  or  medi- 
astinum, may  ultimately  point  at  the  epigastrium.  It  is  not  uncommon  to  find  the  ster- 
nal attachment  of  the  diaphragm  partially  or  entirely  deficient.  ^ 
The  lateral  muscular  fibres,  which  are  much  longer  than  the  anterior,  describe  very 
well-marked  curves,  and  form  an  arch,  with  the  concavity  downward,  but  more  convex 
and  projecting  on  the  right  than  the  left  side.  They  then  divide  into  six  or  seven  digi- 
tations  on  each  side,  which  are  attached  to  the  ribs,  intersecting  with  the  costal  inser- 
tions of  the  transversalis  abdominis.  It  is  not  uncommon  to  find  considerable  intervals 
between  the  digitations  of  this  muscle,  opposite  which  the  pleura  and  peritoneum  are  in 
contact ;  this  more  especially  occurs  between  the  eleventh  and  twelfth  ribs.  The  fas- 
ciculus for  the  twelfth  rib  is  sometimes  deficient,  its  place  being  occupied  by  a  tendon. 
The  direction  of  the  fibres  of  the  diaphragm  is  then  radiated  and  curvilinear  in  the  hori- 
zontal portion,  but  radiated  and  rectilinear  in  the  vertical  portion. 

Relations. — 1.  The  inferior  or  abdominal  surface,  concave  in  the  middle,  and  much  more 
concave  on  the  right  side,  where  it  corresponds  to  the  convex  upper  surface  of  the  liver, 
than  on  the  left,  where  it  is  in  contact  with  the  spleen  and  the  large  extremity  of  the 


214  MYOLOGY. 

Stomach,  is  covered  by  the  peritoneum  throughout  the  greater  part  of  its  exteiit,  except- 
ing at  the  situation  of  the  coronary  ligament  of  the  liver,  and  also  behind,  where  it  is  in 
relation  with  the  third  portion  of  the  duodenum,  the  pancreas,  the  kidneys,  the  supra- 
renal capsules,  and  the  solar  plexus. 

2.  Thoracic,  or  upper  surface.  The  middle  portion  is  convex,  and  covered  by  the  pleu- 
ra and  pericardium ;  it  is  flat,  and  serves  as  a  floor  to  support  the  heart,  the  inferior  sur- 
face of  which  rests  upon  it ;  hence  the  pulsations  of  the  heart  felt  in  the  epigastrium. 
The  lateral  portions  are  convex,  and  contiguous  to  the  lungs.  The  convexity  is  greater 
on  the  right  than  on  the  left  side  :  the  highest  point  to  which  the  right  side  reaches,  in 
the  natural  condition,  is  the  level  of  the  fourth  rib  ;  the  highest  point  which  the  left  side 
attains  is  opposite  the  fifth  rib.  Hence  the  surgical  rule  of  operating  for  empyema  high- 
er on  the  right  than  on  the  left  side.* 

The  height  to  which  the  diaphragm  is  raised  varies  remarkably ;  it  reaches  very  much 
higher  in  the  foetus  than  in  the  adult.  Should  the  muscle  be  only  slightly  vaulted,  it  is 
considered  by  medical  jurists  as  one  of  the  presumptive  proofs  that  the  infant  has  respired. 

3.  Circumference. — ^With  the  exception  of  the  crura,  the  diaphragm  is  connected  by  its 
circumference  only  with  one  muscle,  viz.,  the  transversalis,  which  presents  exactly  cor- 
responding attachments,  so  that,  indeed,  these  two  muscles  may  be  considered  as  form- 
ing one  contractile  sac,  interrupted  by  the  costal  insertions. 

Action. — The  diaphragm  forms  an  active  septum  between  the  thorax  and  abdomen, 
which  affects  the  viscera  of  both  cavities.  The  two  pillars  act  like  the  long  muscles  ; 
the  body  of  the  diaphragm  after  the  manner  of  the  hollow  muscles.  When  the  pillars 
contract,  they  take  their  fixed  point  upon  the  lumbar  vertebrae,  and  their  movable  point 
upon  the  notch  at  the  back  of  the  cordiforra  tendon,  which  is  carried  backward  and  down- 
ward. This  aponeurosis,  in  its  turn,  becomes  a  fixed  point  for  all  the  other  curved  ra- 
diated fibres  that  are  attached  to  the  ribs.  The  first  effect  of  the  contraction  of  a  curved 
fibre  is  its  becoming  straight ;  and,  in  this  process,  the  highest  part  of  the  curve  is  drawn 
down  towards  a  level  with  its  extremities  :  the  vertical  diameter  of  the  thorax  is,  there- 
fore, increased,  and  that  of  the  abdomen  proportionally  diminished ;  but,  during  contrac- 
tion, the  fibres  act  equally  upon  both  their  points  of  insertion,  and,  as  the  cordiform  ten- 
don is  fixed,  and  the  costal  attachments  are  movable,  the  ribs  are  drawn  inward,  and  the 
transverse  diameter  of  the  thoracico-abdominal  cavity  thereby  diminished.  The  antero- 
posterior diameter  would  be  equally  diminished,  were  it  not  for  the  inclination  of  the  di- 
aphragm downward  and  backward,  in  consequence  of  which  the  abdominal  viscera  are 
pressed  downward  and  forward.  Some  experimentalists,  among  whom  we  may  men- 
tion Haller  and  Fontana,  have  asserted  that  the  diaphragm  may  become  convex  below 
during  a  forced  contraction,  but  I  beheve  this  can  only  take  place  when  air  has  been  ad- 
mitted into  the  cavity  of  the  pleura. 

We  shall  now  consider  the  effects  of  the  contraction  of  the  diaphragm  upon  the  open- 
ings by  which  it  is  perforated. 

The  elliptical,  or,  rather,  oval  opening  for  the  oesophagus,  being  entirely  muscular,  is 
contracted  during  the  action  of  the  diaphragm,  in  the  same  manner  as  the  mouth  by  that 
of  the  orbicularis  muscle  :  hence  the  oesophagus  is  compressed.  From  this  it  has  been 
concluded  that  vomiting  cannot  take  place  during  inspiration,  but  experience  proves  the 
contrary,  vomiting  being  favoured  by  this  compression. 

It  is  generally  said  that  the  orifice  for  the  vena  cava  is  not  affected  by  the  contraction 
of  the  diaphragm ;  but  if  we  draw  upon  the  muscular  fibres  in  the  neighbourhood  of  this 
opening,  we  see  at  once  that  it  is  diminished  in  size  ;  HaUer  has  even  witnessed  this  in 
a  living  animal  during  inspiration.  The  arch,  or,  rather,  the  parabolic  canal,  which  gives 
passage  to  the  aorta,  is  also  contracted,  and  the  vessel  slightly  compressed ;  hence, 
doubtless,  arises  the  frequency  of  aneurisms  of  tliis  artery,  where  it  passes  through  the 
pillars  of  the  diaphragm. 


LUMBAR  REGION. 
The  Psoas  and  Illiacus. — Psoas  Parvus.  —Quadratus  iMmborum. 
The  lumbar  region  includes  the  psoas  and  iliacus,  the  psoas  parvus  (when  it  exists), 
and  the  quadratus  lumborum. 

7'he  Psoas  and  Iliacus. 

I  consider  that,  since  the  psoas  and  iliacus  muscles  have  a  common  insertion,  they 
should  be  described  as  a  single  muscle,  having  a  double  origin,  which  we  shall  term  the 
psoas-iliac  muscle. 

Dissection. — Having  opened  the  abdomen,  tear  away  with  the  fingers  the  peritoneum 
covering  the  iliac  fossae  and  the  lumbar  regions.     Remove,  at  the  same  time,  the  intes- 

*  This  rule  should  be  disregarded  :  the  object  of  it  is  to  open  the  thorax  at  the  lowest  part,  so  as  to  give  a 
more  easy  exit  to  the  liquid  ;  but  the  lowest  portion  would  be  behind,  in  the  deep  groove  formed  by  the  dia- 
phragm with  the  parietes  of  the  thorax.  It  is  of  little  importance  to  find  the  most  depending  part ;  it  is  suf- 
ficient to  establish  an  outlet ;  the  fluid  will  always  flow  to  it. 


THE   PSOAS   ANDi,ILIACUS.  215 

tines,  the  stomach,  the  pancreas,  the  kidney,  the  liver,  and  the  spleen ;  detach  the  iliac 
fascia.  In  order  to  see  the  femoral  insertion  of  this  muscle,  divide  the  crural  arch 
through  the  middle.  Dissect  with  care  the  muscles  at  the  anterior  and  superior  part  of 
the  thigh,  especially  the  pectineus,  with  which  this  muscle  is  in  immediate  relation 
Remove  the  adipose  cellular  tissue  which  surrounds  the  crural  vessels  and  nerves. 

The  psoas-iliac  muscle  is  deep-seated,  and  extends  from  the  sides  of  the  vertebral 
column  and  front  of  the  iliac  fossa  to  the  lesser  trochanter  of  the  femur.  It  arises  above 
by  two  very  distinct  muscular  masses  ;  an  internal,  long,  or  lumbar  portion  '[lumbaris, 
sive  psoas,  Riolanus),  the  great  psoas  of  authors  ;  and  an  external,  broad,  or  iliac  portion, 
constituting  the  iliacus  (iliacus  intemus,  Albinus). 

1,  The  lumbar  portion  (psoas  magnus,  from  tpdai,  the  loins,  g  g,  Jig.  Ill)  arises  from 
the  sides  of  the  bodies  of  the  five  lumbar  and  last  dorsal  vertebrae,  and  of  the  correspond- 
ing inter- vertebral  substances,  and  from  the  base  of  the  transverse  processes,  by  means 
of  aponeurotic  fibres,  united  by  tendinous  arches,  which  correspond  to  the  grooves  on 
the  bodies  of  the  lumbar  vertebrae,  so  that  the  muscle  is,  in  reality,  only  attached  to  the 
upper  and  lower  borders  of  the  bodies  of  the  vertebra,  and  to  the  inter-vertebral  sub- 
stances. From  this  double  origin  the  fleshy  fibres  proceed  in  the  form  of  a  conoid  bun- 
dle, compressed  on  the  sides,  and  directed  obliquely  downward  and  outward  ;  the  sum- 
mit of  the  cone  is  flattened,  and  embraced  by  the  ligamentum  arcuatum  ;  the  body  is 
thicker  and  rounded,  and  diminishes  in  size  inferiorly,  as  its  constituent  fibres  are  grad- 
ually attached  to  a  tendon,  which,  though  at  first  concealed  in  its  centre,  afterward  ad- 
vances towards  the  anterior  and  external  surface,  receives  the  fibres  of  the  iliacus,  and 
is  inserted  into  the  lesser  trochanter  of  the  femur.  The  great  psoas,  therefore,  resem- 
bles a  double  cone  or  spindle. 

Its  component  fibres  are  not  fasciculated,  but  are  united  by  a  very  delicate  cellular 
tissue.  The  complete  absence  of  fibrous  tissue  explains  the  weakness  of  this  muscle, 
which  may  be  torn  with  the  greatest  facility,  and  perhaps,  also,  the  frequency  of  its  dis- 
eases. Its  tenderness  in  the  ox  causes  it  to  be  a  favourite  joint  for  the  table,  under  the 
name  of  short  ribs  (aloyau) :  perhaps  this  delicacy  of  texture  is  connected  with  the  pres- 
ence of  a  large  plexus  of  nerves  in  the  substance  of  the  muscle. 

2.  The  iliac  portion  (iliacus  muscle  ;  iliacus  intemus,  Alb.,  i  i,fig.  Ill)  fills  the  internal 
Uiac  fossa.  It  arises  from  the  whole  of  this  fossa,  from  the  crest  of  the  ilium,  the  ilio- 
lumbar ligament,  and  the  base  of  the  sacnun,  and  from  the  anterior  superior  iliac  spine, 
the  notch  below,  the  anterior  inferior  iliac  spine,  and  even  the  capsular  ligament  of  the 
hip-joint.  The  fleshy  fibres  converge,  and  are  immediately  attached  to  the  external 
edge  of  the  common  tendon,  which  we  have  described  as  originating  in  the  substance  of 
the  psoas.  This  tendon,  which  receives  on  its  inner  side  all  the  fibres  of  the  psoas,  and 
even  those  fibres  of  the  iliacus  which  arise  from  the  brim  of  the  pelvis,  runs  along  the 
side  of  the  brim,  diminishing  its  transverse  diameter,  and  emerges  from  the  pelvis  under 
the  crur£d  arch,  passing  through  a  remarkable  groove  between  the  anterior  inferior  spi- 
nous process  of  the  ilimn,  and  the  eminentia  ilio-pectinea.  In  this  situation  all  the  fibres 
of  the  psoas  terminate  ;  those  that  remain  of  the  iliacus  are  successively  attached  to 
the  outside  of  the  tendon,  like  the  barbs  of  a  feather  to  the  shaft,  and  form  a  triangular 
fleshy  bundle,  which  inmiediately  changes  its  direction,  passes  backward,  inward,  and 
downward  among  the  muscles  of  the  thigh,  turns  slightly  round,  so  that  its  anterior  sur- 
face looks  somewhat  inward,  and  its  posterior  surface  outward,  and  is  inserted  into  the 
lesser  trochanter,  which  it  embraces  on  every  side,  even  to  its  base.  It  is  not  uncom- 
mon to  find  the  fasciculus  which  comes  from  the  anterior  inferior  spinous  process  of  the 
iUum  and  the  capsular  ligament  forming  a  very  distinct  muscle,  which  has  been  often 
described  separately,  under  the  name  of  the  ilio-capsulo-trochantericus ;  it  is  inserted 
separately  below  the  lesser  trochanter  into  the  oblique  line  which  extends  from  this  pro- 
cess to  the  linea  aspera. 

Relations. — 1.  The  lumbar  portion  (psoas  magnus)  is  in  relation  anteriorly  with  the 
diaphragm,  the  kidney,  the  ascending  colon  on  the  right  side,  the  descending  colon  on 
the  left,  the  peritoneum,  and  the  psoas  parvus,  when  it  exists.  The  external  Uiac  artery 
and  vein  run  along  the  anterior  surface.  On  the  inside  it  corresponds  to  the  bodies  of 
the  lumbar  vertebrae  and  the  lumbar  vessels  ;  behind,  to  the  transverse  processes  of  the 
lumbar  vertebrae  and  the  quadratus  lumborum.  The  lumbar  plexus  is  situated  posterior- 
ly in  the  substance  of  the  psoas  magnus  ;  this  explains  the  violent  pain  in  the  loins  ex- 
perienced during  repeated  contractions  of  this  muscle,  and,  during  pregnancy,  from  the 
pressure  of  the  gravid  uterus.  2.  The  iliac  portion  lines  the  iliac  fossa ;  it  is  covered 
by  the  peritoneum,  the  caecum,  and  the  end  of  the  small  intestines  on  the  right  side,  and 
by  the  sigmoid  flexure  of  the  colon  on  the  left.  These  two  muscles  form  a  projection  on 
the  inside,  which  reduces  the  transverse  diameter  of  the  brim  of  the  pelvis  from  five 
inches  to  four  and  a  half  3.  The  psoas  and  iliacus  exactly  fill  that  portion  of  the  crural 
arch  in  which  they  are  placed,  so  that  hernias  never  take  place  in  this  situation.  4.  In 
the  thigh,  the  common  tendon  is  separated  anteriorly  from  the  cellular  tissue  of  the 
groin  by  the  deep  femoral  fascia  ;  it  is  in  relation  with  the  crural  nerve,  which  passes 
out  of  the  pelvis  in  the  same  sheath  as,  but  below,  the  psoas,  in  a  groove  between  the 


iJ16  MYOLOGY. 

latter  and  the  iliacus,  between  which  parts  it  forms  the  only  separation.  Behind,  it  is  in 
contact  with  the  anterior  border  of  the  os  coxae  and  the  hip-joint,  a  large  bursa  inter- 
vening, which  often  communicates  with  the  synovial  capsule  of  the  joint,  by  an  opening 
of  variable  size.*  The  inner  edge  of  the  psoas-iliac  muscle  is  in  relation  with  the  outer 
edge  of  the  pectineus,  and  with  the  femoral  artery,  which  it  sometimes  covers.  The 
external  edge  is  at  first  in  relation  with  the  sartorius,  and  afterward  with  the  rectus 
femoris.  The  psoas-iliac  is  also  covered  by  the  lumbo-iliac  fascia  {fascia  iliaca),  which 
will  be  described  hereafter.     (Vide  Aponeurology.) 

Actions. — The  psoas-iliac  muscle  flexes  the  thigh  upon  the  pelvis ;  this  action  is  the 
more  energetic  from  the  fact  of  the  fixed  points  of  insertion  being  both  on  the  vertebral 
column,  and  on  the  iliac  fossa.  The  two  portions  of  the  muscle  do  not  act  in  the  same 
direction  ;  but  when  they  contract  simultaneously,  the  opposite  forces  are  destroyed,  and 
the  traction  upon  the  common  tendon  becomes  direct.  This  muscle  affords  a  remark- 
able example  of  the  reflection  of  a  muscle  over  a  pulley,  which  greatly  increases  the 
power,  by  changing  the  direction  of  insertion  nearly  to  the  perpendicular.  The  action 
of  this  muscle,  therefore,  must  only  be  calculated  from  the  point  of  reflection,  i.  e.,  the 
anterior  edge  of  the  ilium.  It  is  in  semiflexion  that  the  muscle  becomes  perpendicular 
to  the  femur,  and  acts  with  the  greatest  power ;  and,  therefore,  the  Tnomentum  of  the 
muscle  occurs  at  that  period.  The  psoas-iliac  is  at  the  same  time  a  rotator  outward  of  the 
femur,  on  account  of  the  obliquity  of  its  insertion  at  the  inner  and  back  part  of  that  bone. 
When  the  femur  is  fixed,  as  in  standing,  it  draws  the  lumbar  portion  of  the  spine  and  the 
pelvis  forward ;  and  its  iliac  portion  rotates  the  pelvis  so  as  to  turn  the  front  to  the  opposite 
side.     When  the  muscles  of  each  side  act  together,  the  trunk  is  inclined  directly  forward. 

The  Psoas  Parvus. 

This  muscle  (Z  I,  fig.  Ill)  lies  in  front  of  the  preceding ;  it  arises  from  the  twelfth  dor- 
sal vertebra,  the  first  and  sometimes  the  second  lumbar  vertebrae,  and  the  corresponding 
inter-vertebral  substances.  It  forms  a  small,  flat  bundle,  at  first  appearing  to  be  a  de- 
pendance  of  the  psoas  magnus,  but  soon  becoming  isolated  ;  it  terminates  in  a  broad, 
shining  tendon,  which  crosses  the  psoas  magnus  at  a  very  acute  angle,  and  is  inserted 
into  the  upper  part  of  the  ilio-pectineal  eminence,  and  the  corresponding  portion  of  the 
brim  of  the  pelvis.  This  small  muscle  receives  the  lumbo-iliac  aponeurosis  (fascia  ili- 
aca) on  its  outer  edge.  It  is  often  absent ;  we  have  sometimes  seen  it  double.  Its  use 
is  evidently  to  render  the  iliac  fascia  tense,  and  to  tie  down  and  prevent  displacement 
of  the  lumbar  portion  of  the  psoas  magnus.  It  may  assist  in  flexing  the  pelvis  upon  the 
thorax,  as  in  climbing ;  in  the  recumbent  and  supine  position,  if  one  muscle  acts  alone, 
it  inclines  the  pelvis  to  its  own  side ;  but  if  its  fixed  point  be  below,  it  inclines  the  trunk 
to  the  same  side. 

The  Quadratus  Lumborum. 

Dissection. — Expose  the  posterior  surface,  by  carefully  detaching  the  common  mass  Oi 
the  posterior  spinal  muscles  ;  and  to  view  the  anterior,  open  the  abdomen  and  remove 
the  viscera.  This  muscle  is  enclosed  in  a  sheath  formed  by  the  anterior  and  middle  lay- 
ers of  the  posterior  aponeurosis  of  the  transversalis  abdominis ;  divide  this  sheath,  and 
the  muscle  will  be  completely  laid  bare. 

The  quadratus  lumborum  (m  m,  fig.  Ill)  is  quadrilateral  in  shape,  and  broader  below 
than  above  ;  it  is  situated  in  the  lumbar  region,  on  the  sides  of  the  vertebral  column,  be- 
tween the  crest  of  the  ilium  and  the  last  rib. 

Attachments  and  Direction. — It  arises  from  the  ilio-lumbar  ligament,  and  from  about 
two  inches  of  the  adjacent  part  of  the  iliac  crest,  by  aponeurotic  fibres,  which,  on  the 
outer  side  especially,  are  very  long.  These  fibres  are  bound  down  by  others,  crossing 
them  at  right  angles,  and  give  origin  to  the  fleshy  part  of  the  muscles,  which  proceeds 
upward  and  a  little  inward,  in  the  following  manner  :  1 .  Some  of  the  fibres  pass  verti 
cally  upward,  and  are  inserted  into  the  last  rib,  to  an  extent  wliich  varies  in  different  in 
dividuals.  2.  Others  are  directed  very  obliquely  inward,  and  divide  into  four  fleshy  bun- 
dles, inserted,  by  means  of  a  similar  number  of  tendons,  into  the  summits  of  the  transverse 
processes  of  the  four  superior  lumbar  vertebrae.  3.  There  is  most  commonly  a  third 
plane,  anterior  to  the  preceding,  and  consisting  of  fibres,  which  arise  from  the  summits 
of  the  transverse  processes  of  the  third,  fourth,  and  fifth  lumbar  vertebrse,  and  are  in- 
serted into  the  lower  edge  of  the  last  rib. 

Connexions. — The  quadratus  lumborum  somewhat  resembles  the  rectus  abdominis,  in 
being  enclosed  and  bound  down  in  a  very  strong  tendinous  sheath  ;  it  has,  therefore,  no 
direct  relations.  In  front  are  the  kidney,  the  colon,  the  psoas,  and  the  diaphragm  ;  be- 
hind is  the  common  mass  of  the  spinal  muscles,  beyond  which  its  outer  border  some- 
what projects,  especially  below.  Its  most  important  relations  are  with  the  kidney  and 
the  colon.  It  is  the  guide  for  the  necessary  incisions  in  operations  performed  in  this  re- 
gion, particularly  in  nephrotomy. 

*  See  note.  p.  296. 


INTEK-TRANSVERSALES,  RECTUS  CAPITIS  LATERALIS,  AND  8CALENI.    217 

Action. — ^With  its  fixed  point  at  the  crest  of  the  ilium,  this  muscle  depresses  the  last 
rib,  by  means  of  its  costal  insertions,  thus  acting  as  a  muscle  of  expiration  ;  and  it  in- 
clines the  spine  to  its  own  side,  through  the  medium  of  its  vertebral  attachment.  With 
its  fixed  point  above,  it  inclines  the  pelvis  to  its  ow^n  side. 


LATERAL  VERTEBRAL  REGION. 

The  Inter-traTisversales  and  Rectus  Capitis  Lateralis. — Scaleni. 

The  lateral  muscles  of  the  vertebral  column  are  the  inter-transversales  of  the  neck 
and  loins,  the  rectus  capitis  lateralis,  and  the  scaleni.  The  quadratus  lumborum,  already 
described,  belongs  also  to  this  region. 

The  Inter-transversales  and  Rectus  Capitis  Lateralis. 
The  inter-transversales  muscles  exist  only  in  the  neck  and  the  loins ;  in  the  back 
they  are  represented  by  the  intercostals,  an  additional  proof  of  the  analogy  between  the 
ribs  and  the  cervical  and  lumbar  transverse  processes.  Many  celebrated  anatomists,  how- 
ever, admit  the  existence  of  inter-transverse  muscles  in  the  back,  but  they  are  nothing 
more  than  deep-seated  fasciculi  of  the  transverso-spinalis. 

1.  Inter-transversales  of  the  Neck  {a  to  a,  fig.  112). — There  are  two  of  these  muscles  in 
each  inter-transverse  space,  an  interior  and  a  posterior.  They  are  small  quadrilateral 
muscles,  one  arising  from  the  anterior,  the  other  from  the  posterior  margin  of  the  groove 
on  the  transverse  process  below :  from  these  origins  the  fibres  proceed  vertically  upward, 
and  are  inserted  into  the  transverse  process  of  the  vertebra  above. 
They  are  separated  from  each  other  by  the  anterior  branches  of 
the  cervical  nerves  and  by  the  vertebral  artery,  the  canal  for 
which  they  serve  to  complete.  Behind,  they  are  in  relation  Avith 
the  posterior  spinal  muscles,  the  splenius,  the  levator  anguli 
scapulas,  the  transversdis  colli,  and  the  cervicalis  descendens ; 
and  in  part  with  the  rectus  capitis  anticus  major. 

2.  Rectus  Capitis  Lateralis  {h,fig.  112). — This  muscle  may  be 
regarded  as  the  first  posterior  inter-transversalis  of  the  neck,  and 
the  rectus  capitis  anticus  minor,  which  we  shall  presently  de- 
scribe as  the  first  anterior  inter-transversalis.  The  comparative 
size  of  the  rectus  lateralis  is  not  opposed  to  this  view,  for  it  is 
connected  with  the  increased  development  of  the  corresponding 
cranial  vertebra.  It  arises  from  the  transverse  process  of  the 
atlas,  and  proceeds  directly  upward,  to  be  inserted  into  the  jugu- 
lar surface  of  the  occipital  bone,  immediately  behind  the  fossa  of  that  name.  This  mus- 
cle separates  the  jugular  vein,  with  which  it  is  in  contact  in  front,  from  the  vertebral 
artery,  to  which  it  is  contiguous  behind. 

3.  Inter-transversalis  of  the  Loins. — The  absence  of  any  groove  upon  the  lumbar  trans- 
verse processes  would  lead  us  at  once  to  infer  that  in  this  region  there  must  be  only  one 
muscle  in  each  inter-transverse  space.  There  are,  therefore,  five  on  each  side.  The 
first  extends  from  the  transverse  process  of  the  last  dorsal  to  that  of  the  first  lumbar  ver- 
tebra ;  and  the  last  from  the  transverse  process  of  the  fourth  to  that  of  the  fifth  lumbar 
vertebra. 

Action. — These  little  muscles,  by  drawing  the  transverse  processes  towards  each  oth- 
er, incline  that  portion  of  the  vertebral  column  with  which  they  are  connected  towards 
their  own  side  ;  that  is,  the  cervical  muscles  with  the  rectus  lateralis  incline  the  head 
and  neck,  and  those  of  the  lumbar  region  act  upon  the  loins. 

The  Scaleni. 

Dissection. — These  muscles  are,  in  a  great  measure,  displayed  in  the  ordinary  dissec- 
tion of  the  anterior  and  posterior  cervical  regions.  In  order  specially  to  expose  them 
upon  an  entire  subject,  it  is  sufficient  to  dissect  off  the  skin  on  the  sides  of  the  neck,  and 
to  remove  the  omo-hyoid,  the  nerves,  the  cellular  tissue,  and  the  sub-clavicular  lymphat- 
ic glands.  But  in  order  to  demonstrate  the  inferior  attachments  of  these  muscles,  the 
upper  limb  must  be  scarified  by  disarticulating  the  clavicle  at  its  sternal  end,  or,  still  bet- 
ter, by  sawing  the  clavicle  through  the  middle,  dividing  the  great  and  small  pectoral  mus- 
cles, raising  the  stemo-cleido-mastoid,  detaching  the  serratus  magnus,  and  drawing  the 
apex  of  the  shoulder  forcibly  backward. 

The  scaleni  occupy  the  sides  and  lower  part  of  the  neck,  extending  from  the  two  up- 
per ribs  to  the  six  lower  cervical  vertebrae,  sometimes  to  the  atlas  also.  They  are,  there- 
fore, fasciculated  like  all  the  other  vertebral  muscles.  Anatomists  are  not  agreed  con- 
cerning their  number.  Albinus  enumerated  five  on  each  side  ;  Sabatier  reduced  these 
to  three  •,  but  we  agree  with  M.  Boyer,  and  modern  anatomists,  in  admitting  the  exist- 
ence of  two  only,  an  anterior  and  a  posterior.  M.  Chaussier  has  followed  the  example  of  ♦ 
Riolanus,  in  describing  only  one,  which  he  calls  costo-trachelien. 

E  E 


•gJ8  MYOLOGY. 

1.  The  scalenus  anticus  {c,figs.  112,  113,  and  114)  might  be  termed  the  anterior  lorig  in- 
ter-transversalis  colli.  Its  name  sufficiently  indicates  its  triangular  shape,  though  it  rathei 
resembles  a  cone  with  the  base  below  and  the  apex  above. 

Aitachments  and  Direction. — It  arises  from  the  inner  margin  and  upper  surface  of  the 
first  rib,  near  its  middle,  the  point  of  attachment  being  indicated  by  a  tubercle,  with  which 
it  is  highly  important  that  we  should  be  acquainted,  because  it  serves  as  a  guide  in  pla- 
cing a  ligature  upon  the  subclavian  artery,  which  passes  over  the  upper  surface  of  the 
first  rib.  It  arises  by  means  of  a  tendon  that  expands  into  an  aponeurotic  cone,  from  the 
interior  of  which  the  fleshy  fibres  take  their  origin.  These  unite,  form  the  body  of  the 
muscle,  and  proceed  upward  and  inward,  to  be  inserted  by  so  many  separate  tendons  into 
the  anterior  tubercles  of  the  transverse  processes  of  the  sixth,  fifth,  fourth,  and  third  cer- 
vical vertebrae,  and  more  especially  into  the  notches  between  the  two  tubercles  at  the  ex- 
tremities of  these  processes.  It  is  not  unconmfion  to  find  one  or  two  fasciculi  inserted 
into  the  posterior  tubercles. 

Relations. — In  front  and  on  the  outside,  this  muscle  is  in  relation  with  the  clavicle,  from 
which  it  is  separated  by  the  subclavian  muscle  and  vein ;  higher  up,  with  the  stemo- 
mastoid,  the  omo-hyoid,  the  phrenic  nerve,  and  the  transverse  and  ascending  cervical 
arteries.  Behind,  it  is  separated  from  the  posterior  scalenus  by  a  triangular  space,  which 
is  wide  below  to  receive  the  subclavian  artery,  and  narrow  above,  where  it  corresponds 
to  the  brachial  plexus  of  nerves,  by  the  first  two  branches  of  which  the  muscle  is  some- 
times perforated.  On  the  inside,  it  is  separated  from  the  vertebral  artery  by  the  longus 
colli.  The  relations  of  the  scalenus  anticus  to  the  subclavian  vein  and  artery  are  of  the 
highest  importance  to  the  surgeon,  and,  in  order  to  impress  them  upon  the  memory,  I 
propose  to  designate  it  the  muscle  of  the  subclavian  artery.  I  have  seen  both  the  artery 
and  vein  placed  in  front  of  this  muscle. 

The  scalenus  posticus  {d,figs.  112,  113,  and  114)  may  be  termed  the  posterior  long  inter- 
transversalis  colli.  It  is  situated  behind  the  preceding  muscle,  is  of  the  same  shape,  but 
somewhat  larger. 

Attachments  and  Direction. — It  has  two  perfectly  distinct  origins :  one,  anterior  and 
larger,  from  all  that  part  of  the  first  rib  intervening  between  the  depression  for  the  sub- 
clavian artery  and  the  tubercle ;  and  another,  posterior,  from  the  upper  edge  of  the  sec- 
ond rib.  The  latter  attachment  is  sometimes  wanting.  Proceeding  from  this  double 
origin,  the  fleshy  fibres  form  two  small  muscular  bodies,  which  either  remain  distinct,  or 
become  blended  together,  and  pass  upward  and  inward,  to  be  inserted  by  six  separate 
tendons  into  the  posterior  tubercles  of  the  transverse  processes  of  the  six  inferior  cer- 
vical vertebrae.  It  is  not  uncommon  to  find  a  fasciculus  extending  from  the  second  rib 
to  the  atlas. 

Relations. — It  is  separated  from  the  anterior  scalenus  by  the  subclavian  artery  and 
brachial  plexus  ;  and  is  in  relation,  behind,  with  the  cervicaJis  descendens,  transversalis 
colli,  splenius,  and  levator  anguli  scapulae :  on  the  outside,  with  the  serratus  magnus, 
the  transverse  cervical  artery,  and  the  stemo-mastoideus  :  on  the  inside,  with  the  first 
intercostal,  the  first  rib,  the  inter-transversales  of  the  neck,  and  the  cervical  vertebrae. 

Action. — The  scaleni  are  powerful  flexors  of  the  neck,  when  their  fixed  points  are  be- 
low ;  but  when  their  upper  attachments  are  fixed,  they  tend  to  elevate  the  first  rib,  and 
in  a  slight  degree  the  second  also. 


DEEP  ANTERIOR  CERVICAL,  OR  PREVERTEBRAL  REGION. 

The  Recti  Capitis  Antici,  Major  et  Minor. — Longus  Colli. — Action  of  these  Muscles. 

This  region  includes  three  pairs  of  muscles  placed  immediately  in  front  of  the  cervical 
and  three  superior  dorsal  vertebrae,  viz.,  the  rectus  capitis  anticus  major,  the  rectus  capi- 
tis anticus  minor,  and  the  longus  colli.  Their  arrangement  is  extremely  complicated  and 
very  difficult  of  elucidation,  unless  we  consider  them  in  the  same  general  manner  al- 
ready adopted  with  regard  to  the  disposition  of  the  posterior  spinal  muscles.  Let  us 
suppose,  then,  that  there  exists  in  the  median  line  of  the  basilar  process  of  the  occipital 
bone  and  the  anterior  surface  of  the  bodies  of  the  cervical  vertebrae  a  series  of  spinous 
processes  (a  supposition  which  is  realized  in  some  animals) ;  then  the  rectus  capitis  an- 
ticus major  would  be  a  transverso-spinalis,  the  rectus  minor  an  anterior  inter-transversalis 
between  the  occipital  bone  and  the  atlas,  and  the  longus  colli  would  be  a  compound  mus- 
cle, its  lower  fibres  forming  a  spino-transversalis,  its  upper  fibres  a  transverso-spinalis, 
and  its  internal  fibres  a  spinalis.  All  this  wiU  be  rendered  apparent  from  the  following 
description. 

Dissection. — Remove  the  face  and  all  the  parts  which  cover  the  cervical  portion  of  the 
spine  by  the  vertical  section,  called  the  section  of  the  pharynx,  because  it  is  also  employed 
in  demonstrating  that  part.  In  order  to  separate  the  face  from  the  cranium,  remove  the 
roof  of  the  scull  by  a  horizontal  section,  and  then  make  a  vertical  cut  either  from  above 
or  from  below  ;  if  we  cut  from  above,  we  may  adopt  the  usual  plan  of  directing  the  saw 
transversely,  so  as  to  emerge  immediately  in  front  of  the  auditorj'  meatus  :  in  doing  this, 


THE   RECTUS    CAPITIS   ANTICUS    MAJOR,  ETC.  "!?t1) 

however,  we  are  in  danger  of  injuring  the  superior  attachments  of  the  recti,  or  of  cutting 
into  the  pharynx.  We  prefer,  therefore,  the  following  method :  make  two  sections  with 
the  saw  obliquely  forward  and  inward  in  the  course  of  the  occipito-mastoid  and  petro- 
occipital  sutures,  and  having  arrived  at  the  basilar  process,  cut  it  across  with  a  chisel, 
a  little  in  front  of  the  anterior  condyloid  foramina.  In  separating  the  face  from  the  cra- 
nium from  below  upward,  a  great  number  of  muscles  must  be  scarified :  the  preceding 
section  is  therefore  preferable,  although  it  is  somewhat  more  difficult. 

The  Rectus  Capitis  Anticus  Major. 

This  muscle  {e,figs.  112  and  114),  the  transverso-spinalis  anterior  (rectus  capitis  in- 
temus  major,  Alb.),  is  the  most  external  of  those  in  the  prevertebral  region. 

Attachments  and  Direction. — It  arises  from  the  anterior  tubercles  of  the  transverse  pro- 
cesses of  the  sixth,  fifth,  fourth,  and  third  cervical  vertebrae,  by  small  tendons,  to  which 
as  many  fleshy  fasciculi  succeed ;  these  pass  obliquely  upward  and  inward,  overlying 
and  blending  with  each  other,  and  terminate  on  the  posterior  surface  and  edges  of  a  shi- 
ning aponeurosis,  that  occupies  almost  entirely  the  anterior  aspect  of  the  muscle.  This 
aponeurosis  itself  becomes  a  surface  of  origin,  dividing  into  two  lamina;,  from  the  bor- 
ders of  and  interval  between  which  a  fleshy  bundle  ascends,  to  be  inserted  into  the  basi- 
lar process  in  front  of  the  foramen  magnum.  The  fasciculus  arising  from  the  third  cer- 
vical vertebra  does  not  join  the  common  insertion,  but  is  attached  directly,  and  in  a  very 
distinct  manner,  to  the  basilar  process  within  and  behind  the  common  fasciculus.  The 
muscle  must  be  turned  outward  in  order  to  display  this  structure. 

Relations. — It  is  covered  by  the  pharynx,  the  internal  carotid  artery  and  jugular  vein, 
the  superior  cervical  ganglion  and  trunk  of  the  great  sympathetic  nerve,  and  the  par  va- 
gum,  being  separated  from  all  these  parts  by  some  loose  cellular  tissue  and  the  preverte- 
bral aponeurosis.  It  covers  the  corresponding  vertebrae,  the  articulation  of  the  occipital 
bone  with  the  atlas,  and  that  of  the  atlas  with  the  axis,  a  portion  of  the  longus  colli,  and 
also  of  the  rectus  minor. 

The  Rectus  Capitis  Anticus  Minor. 

This  muscle  {f,fig-  112),  the  inter-transversalis  anterior  (re^ctus  capitis  internus  mi- 
nor, Alh.),  extends  from  the  base  of  the  transverse  process  and  from  the  adjacent  part 
of  the  lateral  mass  of  the  atlas,  to  the  basilar  process  of  the  occipital  bone.  It  is  partial- 
ly covered  by  the  rectus  major,  which  is  nearer  the  mesial  plane  :  the  superior  cervical 
ganglion  of  the  sympathetic  rests  upon  it,  and  it  covers  the  atloido-occipital  articulation. 
It  may  be  regarded  as  an  anterior  inter-transversalis  between  the  occipitcd  bone  and  the 
atlas,  the  rectus  laterahs  constituting  the  posterior  inter-transversalis. 

The  Longus  Colli. 

Attachments,  Direction,  and  Relations. — The  longus  coUi  {g,g,figs.  112  and  114),  as  be- 
fore stated,  is  composed  of  three  very  distinct  sets  of  fasciculi :  1.  The  transverso-spina- 
lis, which,  arising  by  flat  tendons  from  the  anterior  tubercles  of  the  transverse  processes 
of  the  fifth,  fourth,  and  third  cervical  vertebra;,  unite  so  as  to  form  a  considerable  fleshy 
bundle  directed  upward  and  inward,  occupy  the  hollow  on  each  side  of  the  median  line 
of  the  axis,  and  are  inserted  into  the  anterior  tubercle  of  the  atlas,  which  may  be  regard- 
ed as  the  representative  of  an  anterior  spinous  process  :  2.  The  anterior  spino-transver- 
salis,  the  least  numerous  of  all,  arise  from  the  bodies  of  the  three  superior  dorsal  verte- 
brae by  very  slight  tendinous  expansions,  proceed  upward  and  outward,  and  are  inserted 
into  the  anterior  tubercles  of  the  transverse  processes  of  the  fourth  and  third  cervical 
vertebrae  :  3.  The  spinalis  which  arise,  to  the  inner  side  of  the  preceding  fasciculi,  from 
the  bodies  of  the  three  upper  dorsal  and  four  lower  cervical  vertebrae,  and  from  the  in- 
termediate ligaments,  and  having  described  a  slight  curve,  are  inserted  into  the  crest  of 
the  axis  and  into  the  third  cervical  vertebra.  The  longus  colli  is  elongated  and  fusiform 
in  shape ;  it  supports  the  pharynx,  the  oesophagus,  the  internal  carotid  artery,  the  inter- 
nal jugular  vein,  and  the  pneumogastric  and  great  sympathetic  nerves :  it  covers  the 
vertebrae  to  which  it  is  attached. 

Action  of  the  Muscles  of  the  deep  Anterior  Cervical  Region. 

When  the  head  is  thrown  back,  these  muscles  restore  it  to  its  original  position.  The 
rectus  anticus  major  tends  to  flex  the  head,  and  from  its  obliquity  to  rotate  it,  so  as  to 
turn  the  face  to  its  own  side.  The  rectus  minor  inclines  the  head  to  its  own  side.  The 
longus  colli  flexes  the  atlas  upon  the  axis,  and  rotates  it  so  as  to  turn  the  face  to  its  own 
Bide.  '^I'he  same  muscle  also  rotates  the  lower  part  of  the  neck,  so  as  to  turn  the  face 
to  the  opposite  side  •  and,  lastly,  it  is  a  direct  flexor  of  the  cervical  region. 


MYOLOGY. 


THORACIC  REGION 


The  Pectoralis  Major. — Pectoralis  Minor. — Subclavius. — Serratus  Magnus. — Intcrcostales 
— Supra-costales. — Infra-costales. — Triangularis  Sterni. 

The  Pectoralis  Major. 

Dissection. — Separate  the  arm  from  the  side.  Make  a  horizontal  incision  from  the  top 
of  the  sternum  to  the  front  of  the  arm  on  a  level  with  the  lower  border  of  the  axilla,  in- 
cluding in  this  incision  a  fascia  which  adheres  closely  to  the  fleshy  fibres.  Reflect  one 
of  the  flaps  upward  and  the  other  downward,  by  dissecting  parallel  to  the  fibres,  i.  e., 
transversely  to  the  axis  of  the  body. 

The  ■pectoralis  major  (c  c,  fig.  109)  is  a  broad,  thick,  triangular  muscle,  situated  at  the 
upper  and  fore  part  of  the  thorax  and  axilla.  It  arises  from  the  anterior  border  of  the 
clavicle  and  anterior  surface  of  the  sternum,  from  the  cartilages  of  the  second,  third, 
fourth,  and  more  particularly  those  of  the  fifth  and  sixth  ribs,  from  the  osseous  portion 
of  the  last-mentioned  rib,  and  from  the  abdominal  aponeurosis  :  it  \s  inserted  into  the  an- 
terior margin  of  the  bicipital  groove  of  the  humerus. 

The  clavicular  origin  consists  of  short  tendinous  fibres  attached  to  the  entire  breadth 
of  the  anterior  border  of  the  clavicle,  for  about  the  inferior  third,  or  half  of  its  extent. 

The  sternal  attachment  consists  of  aponeurotic  fibres,  which,  intersecting  with  those  of 
the  opposite  muscle,  form,  in  front  of  the  sternum,  a  very  thick  fibrous  layer,  sometimes 
ahnost  completely  covered  by  the  muscular  fibres,  which,  in  certain  individuals,  advance 
nearly  to  the  median  line. 

The  costal  origins  consist  of  very  thin  tendinous  laminae,  and  the  attachment  to  the 
abdominal  aponeurosis  is  blended  with  that  of  the  rectus  abdominis. 

From  these  different  origins  the  fleshy  fibres  proceed  outward  in  different  directions  ; 
the  upper  fibres  obliquely  downward,  the  middle  transversely,  and  the  lower  fibres  oblique- 
ly. These  last  are  folded  backward,  so  as  to  form  a  sort  of  groove,  which  embraces  the 
lower  border  of  the  pectoralis  minor.  It  appears,  then,  that  the  pectoralis  major  is  com- 
posed of  three  very  distinct  portions,  which  are  sometimes  separated  by  a  greater  or 
less  quantity  of  cellular  tissue.  These  three  portions,  in  converging,  are  so  disposed  that 
the  upper  overlaps  the  middle,  and  this,  again,  the  lower  portion,  the  fibres  of  which  are 
twisted  upon  themselves,  so  that  the  lowest  in  front  become  the  highest  behind,  and  vice 
versa.*  They  are  all  inserted  into  the  anterior  lip  of  the  bicipital  groove  by  means  of  a 
flat  tendon,  about  fifteen  lines  in  breadth,  which  is  continuous  with  the  anterior  edge  of 
the  tendon  of  the  deltoid.  The  structure  of  this  tendon  commands  particular  attention, 
and  can  only  be  examined  after  having  divided  the  muscle  across,  and  turned  the  exter- 
nal half  outward.  It  will  then  be  seen  that  it  is  composed  of  two  laminae,  placed  one  be- 
fore the  other,  sometimes  blended  together,  but  generally  distinct,  or  united  only  by 
their  lower  edges,  so  that  they  form  a  groove  opening  upward.  The  anterior  lamina  is 
the  thicker,  and  receives  the  clavicular  and  middle  portions  of  the  muscle  ;  the  deep  lay- 
er affords  attachment  to  the  lower  portion.  It  is  not  uncommon  to  find  the  two  laminae 
separated  by  the  tendon  of  the  long  head  of  the  biceps,  the  groove  for  which  they  then 
contribute  to  form.  The  entire  tendon  is  broader  and  thicker  below  than  above,  and 
gives  off,  both  forward  and  backward,  an  aponeurotic  expansion,  constituting  one  of  the 
chief  origins  of  the  fascia  of  the  arm.t 

Relations. — It  is  covered  by  the  platysma  myoides,  the  mammary  gland,  and  the  skin. 
Its  deep  relations  are  of  the  greatest  importance.  On  the  thorax  it  covers  the  sternum, 
the  ribs  and  their  cartilages,  the  pectoralis  minor,  the  subclavius  nauscle,  the  serratus 
m£ignus,  and  the  intercostals.  It  forms  the  anterior  wall  of  the  axilla,  and  is  in  relation 
with  the  brachial  plexus  and  axillary  vessels,  and  with  the  cellular  tissue  and  lymphatic 
glands  of  that  region.  Its  external  border  is  nearly  parallel  to  the  anterior  edge  of  the 
deltoid,  being  separated  from  the  latter  by  a  linear  or  triangular  cellular  interval,  in 
which  are  situated  the  cephalic  vein  and  acromial  artery.  Its  lower  border  is  thin  towards 
the  median  line,  thick  and  tendinous  externally ;  it  forms  the  anterior  border  of  the  ax- 
illa, and  gives  rise  to  a  projection  under  the  skin,  proportionate  to  the  development  of  the 
muscle.  Its  inner  border  intersects  in  the  median  line  with  the  muscle  of  the  opposite 
side,  and  is  continuous  below  with  the  linea  alba. 

Uses. — The  pectoralis  major  is  essentially  an  addTictor  of  the  arm ;  at  the  same  time  it 
rotates  it  inward,  and  draws  it  forward.  It  is  by  the  action  of  this  muscle  that  the  fore- 
arms are  crossed,  and  that  one  hand  is  placed  on  the  opposite  shoulder.  Its  upper  or 
clavicular  portion  conspires  with  the  anterior  fibres  of  the  deltoid  and  with  the  coraco- 
brachialis  in  elevating  the  humerus,  and  carrying  it  forward. 

*  I  believe  that  this  overlapping  and  folding  of  the  muscular  fibres  tend,  reciprocally,  to  prevent  the  dis- 
placement of  any  individual  portion  of  the  muscle. 

t  I  have  once  observed  a  very  slender  muscular  fasciculus,  arising'  from  the  abdominal  aponeurosis,  proceed 
along  the  inferior  border  of  the  pectoralis  major,  from  which  it  was  perfectly  distinct,  and  terminate  in  a  small 
tendon  opposite  the  humeral  insertion  of  that  muscle.  This  tendon  was  continued  along-  the  inner  side  of  the 
arm,  adhered  to  the  aponeurotic  inter-muscular  septum,  from  which  it  received  a  small  fleshy  fasciculus,  and 
was  ultimately  inserted  into  the  epitrochlea 


IHB  FECTORALIS  MINOR,  SUBCLAVIUS,  AND   SERRATUS   MAGNUS.       2l2t 

If  the  arm  be  at  a  moderate  distance  from  the  side  and  its  lower  extremity  be  fixed, 
as  is  the  case  in  falling  on  the  elbow  when  the  arm  is  directed  outward,  this  muscle  acts 
upon  the  humerus  as  upon  a  lever  of  the  third  order,  of  which  the  fulcrum  is  below,  the  pow- 
er in  the  middle,  and  the  resistance  above  ;  and  it  then  tends  to  dislocate  the  bead  of  the 
humerus  •with  great  force,  because  in  this  position  its  insertion  is  perpendicular  to  the  lever. 

When  the  humerus  is  fixed,  the  pectoralis  major  acts  upon  the  ribs,  the  sternum,  and 
the  clavicle,  and  raises  the  trunk  upon  the  arm.  It  is,  therefore,  one  of  the  chief  agents 
in  climbing.  Its  action  upon  the  ribs  renders  it  an  important  auxiliary  in  cases  of  la- 
borious inspiration.  Hence  the  attitude  of  an  asthmatic  patient,  who  always  nlaces  him- 
self so  as  to  keep  the  humeri  fixed. 

The  Pectoralis  Minor. 

Dissection. — Detach  the  clavicular  insertion  of  the  pectoralis  major,  and  divide  that 
muscle  in  the  middle  by  a  verticle  incision  ;  reflect  the  two  flaps,  taking  care  to  remove, 
at  the  same  time,  the  loose  cellular  tissue  which  invests  its  deep  surface. 

The  pectoralis  minor  {t,fi.g.  110)  is  a  thin,  flat,  triangular  muscle,  having  its  internal 
edge  serrated  (serratus  anticus,  Albinus),  and  occupying  the  anterior  and  upper  part  of 
the  thorax  and  shoulder.  It  arises  from  the  third,  fourth,  and  fifth  ribs,  by  three  delicate, 
shining,  tendinous  prolongations,  lying  superficially  to  the  intercostal  muscles  ;  to  these 
succeed  three  fleshy  fasciculi,  which  unite  and  converge,  so  as  to  be  inserted  by  a  flat 
tendon  into  the  anterior  margin  of  the  coracoid  process,  near  its  summit. 

Relations. — It  is  covered  by  the  pectoralis  major,  from  which  it  is  separated  by  the  tho- 
racic vessels  and  nerves  :  its  posterior  surface  is  in  relation  with  the  ribs,  the  intercos- 
tal muscles,  the  serratus  magnus,  the  cavity  of  the  axilla,  and,  therefore,  with  the  axillary 
vessels  and  nerves.  This  last  relation  is  of  great  importance,  and  sometimes  renders 
the  section  of  this  muscle  necessary  for  the  ligature  of  the  axillary  artery.  Attention 
should  also  be  directed,  1 .  To  its  upper  border,  which  is  separated  from  the  clavicle  by 
a  triangular  interval,  broad  on  the  inside  and  narrow  on  the  outside,  in  which  the  same 
artery  may  be  tied ;  and,  2.  The  lower  border  of  the  muscle  extends  downward  beyond 
the  pectoralis  major. 

Action. — Most  commonly  it  acts  upon  the  scapula  (musculus  qui  scapulam  antrorsum 
agit,  Vesalius).  With  its  fixed  point  at  the  ribs,  it  evidently  draws  the  scapula  forward 
and  downward,  and  forcibly  depresses  the  apex  of  the  shoulder.  As  a  depressor  of  the 
shoulder,  it  acts  in  conjunction  with  the  levator  anguli  scapulae  and  rhomboideus,  but  an- 
tagonizes those  muscles  considered  as  elevators  of  the  entire  scapula  :  it  is  also  opposed 
to  the  rhomboideus  when  moving  the  scapula  forward.  With  its  fixed  point  at  the  scapu- 
la, this  muscle  elevates  the  ribs  to  which  it  is  attached. 

The  Subclavius. 

Dissection. — Raise  the  clavicle  by  carrying  the  apex  of  the  shoulder  upward ;  divide 
the  pectoralis  minor,  and  remove  the  fibrous  membrane,  descending  from  the  clavicle, 
and  immeidiately  investing  the  muscle.  In  order  to  expose  its  external  or  clavicular  in- 
sertion, saw  through  the  clavicle  in  the  middle,  divide  the  muscle  at  the  same  point,  and 
reflect  the  external  half  with  the  corresponding  portion  of  the  clavicle. 

The  subclavius  (g,fig.  110)  is  a  long,  thin,  fusiform  muscle,  applied  to  the  lower  sur- 
face of  the  clavicle,  by  which  it  is  concealed  (musculus  qui  sub  clavicula  occultatur,  Fa- 
bricius  Hildanus).  It  arises  from  the  cartilage  of  the  first  rib,  and  is  inserted  into  the  in- 
ferior and  external  surface  of  the  clavicle.  Its  costal  attachment  consists  of  a  cervical 
tendon,  from  which  the  fleshy  fibres  proceed  outward,  backward,  and  upward,  and  are  in- 
serted into  the  clavicle  by  short,  tendinous  fibres. 

Relations. — It  is  covered  above  by  the  clavicle,  which  is  grooved  beneath  for  its  recep- 
tion ;  it  is  in  relation  below  with  the  first  rib,  being  separated  from  it  by  the  axillary  ves- 
sels and  the  brachial  flexus ;  in  front,  it  is  enveloped  by  a  very  strong  aponeurosis,  com- 
pleting the  osteo-fibrous  canal  in  which  it  is  included.  Its  relation  with  the  brachial 
plexus  and  axillary  vessels  prevents  the  direct  compression  to  which  these  parts  would 
have  been  otherwise  exposed  between  the  clavicle  and  the  first  rib. 

Action. — ^When  its  fixed  point  is  at  the  first  rib,  it  depresses  the  clavicle,  and  is,  there- 
fore, a  depressor  of  the  shoulder ;  it  tends  also  to  press  the  inner  end  of  the  clavicle  for- 
cibly against  the  sternum ;  so,  also,  in  fracture  of  the  clavicle,  it  occasions  the  external 
fragment  to  ride  upon  the  internal.  When  its  fixed  point  is  at  the  clavicle,  it  assists  in 
elevating  the  first  rib,  and  is,  therefore,  arranged  among  the  muscles  that  act  in  impeded 
inspiration. 

The  Serratus  Magnus. 
Dissection. — Having  removed  the  two  pectorals,  saw  through  the  clavicle  at  its  mid- 
dle ;  press  the  scapula  backward,  directing  its  axillary  edge  outward  ;  remove  with  care 
the  cellular  tissue  occupying  the  axilla,  especially  that  against  the  axillary  vessels  and 
nerves,  and  near  the  intercostal  attachments  of  the  muscle  itself,  in  order  to  see  the  in- 
ternal surface  of  which  the  subject  must  be  turned,  and  the  vertebral  eosta  of  the  scap- 
ula drawn  outward. 


222  XM.i*    -  MYOLOGY. 

The  serratus  magnus  [u,fig.  106,  d,  109,  and  I,  110),  very  broad,  quadrilateral,  and  ser- 
rated along  one  of  its  borders,  occupies  the  side  of  the  thorax,  and  extends,  hke  a  mus- 
cular girth,  from  the  ten  upper  ribs  to  the  vertebral  costa  of  the  scapula.  Its  costal  at- 
tachments consist  of  nine  or  ten  digitations  arranged  in  a  curve,  having  its  concavity  di- 
rected backward.  The  first  digitation,  which  is  very  large,  arises  both  from  the  first 
and  second  ribs,  and  from  an  aponeurotic  arch  between  them  ;  from  thence  tlie  fibres 
proceed  upward,  outward,  and  backward,  and  are  inserted  into  the  inner  surface  of  the 
posterior  and  superior  angle  of  the  scapula,  near  the  levator  anguli.  This  digitation  is 
the  narrowest  part  of  the  muscle  ;  it  differs  in  direction  from  the  remainder,  and  is  sep- 
arated from  them  by  a  cellular  interval ;  hence  it  has  been  termed  the  superior  portion 
of  the  serratus  magnus.  The  second,  third,  and  fourth  digitations  arise  in  an  oblique 
line,  running  downward  and  forward  from  the  second,  third,  and  fourth  ribs.  These  are 
the  largest  and  the  thinnest  of  all  the  digitations  ;  they  proceed  horizontally  backward, 
and  are  inserted  separately,  by  short  tendinous  fibres,  into  the  entire  length  of  the  verte- 
bral costa  of  the  scapula,  anterior  to  the  rhomboid  ;  they  are  distinguished  from  the  re- 
maining digitations  both  by  their  direction  and  by  an  intervening  cellular  space ;  they 
form  the  middle  portion  of  the  serratus  magnus. 

The  fifth,  sixth,  seventh,  eighth,  ninth,  and  tenth  digitations  arise  from  the  outer  sur- 
face of  the  corresponding  ribs  along  oblique  lines,  resembling  the  fingers  crossed,  and 
are  interposed  between  corresponding  prolongations  of  the  external  oblique.  These  di- 
gitations are  at  first  tendinous ;  they  soon  become  fleshy,  and,  converging  towards  each 
other,  form  a  radiated  fasciculus,  which  passes  upward,  outward,  and  backward,  to  be 
inserted  into  the  internal  surface  of  the  inferior  angle  of  the  scapula.  This  is  the  infe- 
rior portion  of  the  serratus  magnus. 

Relations. — The  serratus  rnagnus  is  partially  covered  by  the  two  pectorals  before,  by 
the  subscapularis  behind,  and  above  by  the  axillary  vessels  and  nerves  ;  its  deep  surface 
rests  upon  the  ribs  and  the  intercostal  spaces,  all  these  parts  being  united  by  a  quantity 
of  loose  cellular  tissue.  A  considerable  portion  of  the  lower  part  of  the  muscle  is  sub- 
cutaneous, and,  therefore,  the  inferior  digitations  are  important  studies  for  the  painter 
and  the  sculptor,  and  sometimes  even  for  the  surgeon,  as  indications  of  the  arrangement 
of  the  corresponding  ribs. 

Action. — From  the  disposition  of  its  different  fasciculi,  the  serratus  magnus  occasions 
a  compound  movement  of  the  scapula,  which  it  will  be  well  to  analyze.  The  upper  por- 
tion depresses  and  brings  forward  the  apex  of  the  shoulder  ;  the  middle  portion  draws 
the  entire  scapula  directly  forward ;  while  the  lower  portion  depresses  it,  and,  more- 
over, rotates  it,  so  that  the  apex  of  the  shoulder  is  carried  upward.  As  the  lower  part 
of  the  muscle  is  composed  of  six  or  seven  of  the  converging  fasciculi,  which  act  with 
greater  energy  than  the  others,  it  follows  that  their  action  predominates  even  when  the 
whole  muscle  contracts.  The  serratus  magnus  is,  then,  a  depressor  of  the  entire  shoulder, 
and  an  elevator  of  its  apex.  It  is  more  especially  concerned  than  any  other  muscle  in 
supporting  a  burden  upon  the  shoulder. 

In  order  that  the  action  of  the  serratus  may  be  directed  upon  the  scapula,  its  costal 
attachments  must  be  fixed :  this  requires  the  simultaneous  contraction  of  the  oblique 
muscles  of  the  abdomen  to  maintain  the  ribs  in  a  depressed  position,  and  of  the  dia- 
phragm and  transversalis  to  prevent  their  projection  outward.  This  simultaneous  con- 
traction occurs  during  all  great  efforts. 

When  the  fixed  point  of  the  serratus  magnus  is  at  the  scapula,  its  upper  portion  be 
comes  a  muscle  of  inspiration,  its  middle  one  of  expiration,  and  its  lower  one  of  inspira 
tion.  The  greater  power  of  the  latter  has  been  the  cause  of  the  antagonizing  action  of 
the  middle  portion  being  overlooked ;  and  the  serratus  magnus  is,  with  great  justice,  re 
garded  as  the  most  powerful  accessory  muscle  of  inspiration :  hence  the  various  atti- 
tudes of  asthmatic  persons,  who  instinctively  take  a  position  which  fixes  the  scapula, 
either  by  seizing  a  cord  suspended  from  the  top  of  the  bed,  or  by  bending  forward,  anc" 
leaning  on  their  elbows  and  forearms,  or  by  resting  their  upper  extremities  on  two  lat 
eral  supports. 

The  Inter-costales,  Externi  and  Interni ;  the  Supra-costdles  and  the  Infra 

costales. 

Dissection. — In  order  to  examine  the  extemeil  intercostals  and  the  supra-costales  (le 
vatores  costarum),  the  scapula  and  all  the  muscles  which  cover  the  thorax  must  be  re 
moved ;  to  expose  the  internal  inter-costales  and  the  infra-costales,  it  is  necessary  to 
saw  through  the  middle  of  the  dorsal  vertebrae  and  the  sternum  in  a  vertical  direction, 
and  to  tear  off  the  pleura  from  one  side  of  the  thorax,  which  may  be  very  easily  accom 
plished  by  the  fingers. 

The  intercostal  muscles,  as  their  name  implies,  occupy  the  intervals  between  the  ribs 
there  are  two  in  each  intercostal  space,  and,  therefore,  as  many  pairs  as  there  are  spaces. 

They  are  divided  into  external  and  internal.  They  represent  two  very  tliin  muscular 
layers,  of  exactly  the  same  width  as  the  spaces  to  which  they  belong ;  taken  together. 


THE    INTER-COSTALES,   SUPRA-COSTALES,   AND    INFRA-COSTALES.      223 

they  also  occupy  the  entire  length  of  those  spaces,  but  not  separately,  for  the  external 
intercostals  extend  only  from  the  costo-vertebral  articulations  to  the  commencement  of 
the  cartilages  of  the  ribs,  while  the  internal  intercostals  commence  at  the  angles  of  the 
ribs  behind,  and  extend  forward  to  the  sternum.  A  very  thin  aponeurosis  is  prolonged 
from  the  free  margin  of  the  one  forward  and  of  the  other  backward  to  the  end  of  the  in- 
tercostal space.  The  external  muscles,  which  I  have  generally  found  thicker  than  the 
internal,  arise  from  the  lip  of  the  groove  on  the  lower  border  of  one  rib,  and  the  internal 
from  the  inner  hp  of  the  same  groove,  as  well  as  from  the  corresponding  costal  carti- 
leige ;  they  are  both  inserted  into  the  upper  border  of  the  rib  below.  The  superior  at 
tachments  consist  of  fleshy  and  tendinous  fibres  and  lamellae,  all  of  which  proceed  down- 
ward to  the  rib  below ;  those  of  the  external  layer  obliquely  forward,  and  those  of  the 
internal  layer  much  l6ss  obliquely  backward.  The  inferior  attachments  are  similar  in 
structure.  The  tendinous  fibres  of  the  intercostal  muscles  are  very  long,  and  much 
more  numerous  than  the  fleshy  fibres  :  hence  the  intercostal  spaces  possess  consider- 
able strength,  to  which  the  crossing  of  the  two  layers  also  contributes. 

Relations. — The  external  intercostals  are  covered  by  the  two  pectorals,  the  serratus 
magnus,  the  serrati  postici,  the  latissimus  dorsi,  the  sacro-lumbalis,  and  the  external  ob- 
lique ;  they  are  superficial  to  the  internal  intercostals,  and  are  separated  from  them  by  the 
intercostal  vessels  and  nerves,  and  by  a  very  thin  fibrous  layer.  The  internal  intercostala 
are  covered  by  the  external  and  by  the  aponeurotic  layer  continuous  with  them  anterior- 
ly. Internally  they  are  in  relation  with  the  pleura,  which,  from  the  angles  to  the  tuber- 
osities of  the  ribs,  is  in  apposition  with  the  external  muscles. 

The  infracostal  muscles  of  Verheyen  consist  of  small  muscular  and  aponeurotic  tongues, 
variable  in  number  and  length,  which  extend  from  the  inner  surface  of  one  rib  to  the  in- 
ner surface  of  the  next,  and  sometimes,  also,  to  the  second  or  third  rib  below.  They  are 
sometimes  vertical,  but  often  oblique,  like  the  internal  intercostals,  of  which  they  may 
be  regarded  as  portions. 

Supra-costales  (levatores  breviores  costarum  of  Alhinus,  o  to  o,fig.  107).  These  are 
small  triangular  muscles,  situated  at  the  back  part  of  the  intercostal  spaces.  They  are 
accessories  of  the  external  intercostals,  resemble  them  in  being  half  tendinous  and  half 
fleshy,  and  appear  to  form  a  continuation  of  them.  There  are  twelve  on  either  side. 
Each  arises  from  the  summit  of  the  transverse  process  of  a  vertebra,  and  proceeds  in  a 
radiated  manner  downward,  to  be  inserted  into  the  back  part  of  the  upper  border  and  ex- 
ternal surface  of  the  rib  below. 

The  fibres  of  these  muscles  have  the  same  direction  as  those  of  the  external  intercos- 
tals, but  they  are  more  obhque,  especially  on  the  outside.  The  first  arises  from  the  trans- 
verse process  of  the  seventh  cervical  vertebra,  the  last  from  that  of  the  eleventh  dorseil. 
Some  of  these  muscles  have  two  digitations,  one  disposed  in  the  ordinary  manner,  the 
other  attached  to  the  next  rib  below.  The  latter,  called  the  long  supra-costals  (levatores 
longiores,  Albinus  and  Haller),  form  a  transition  between  the  levatores  breviores  and  the 
serrati.  Morgagni  met  with  all  the  levatores  united  together,  so  as  to  form  a  very  reg- 
ular serrated  muscle.  They  are  covered  by  the  longissimus  dorsi  and  sacro-lumbaUs, 
and  they  cover  the  external  intercostals. 

Action. — The  contraction  of  the  intercostal  muscles  tends  to  approximate  the  ribs  ; 
and,  according  as  the  upper  or  the  lower  ribs  are  fixed,  they  act  as  muscles  of  inspira- 
tion or  of  expiration.  It  has  never  been  denied  that  the  external  intercostals  are  mus- 
cles of  inspiration,  but  the  crossing  of  the  tAvo  muscidar  layers  has  given  rise  to  the  opin- 
ion that  they  oppose  each  other  in  action  ;  and  hence  arose  the  celebrated  dispute  be- 
tween Bamberger  and  Haller.  It  is  easy  to  understand  that  the  slight  difference  exist- 
ing between  their  attachments,  with  regard  to  their  distance  from  the  fulcrum,  could  not 
counterbalance  the  effect  of  a  difference  in  the  relative  fixedness  of  the  ribs,  and  that  the 
intercrossing  of  these  muscles  has  no  other  object  than  to  increase  the  strength  of  the 
parietes  of  the  thorax. 

As  the  first  rib  is  much  more  fixed  than  the  last,  it  follows  that  it  must  serve  as  a  fixed 
point  for  the  first  intercostal  muscle,  which  will  consequently  raise  the  second  rib  ;  this 
will  then  become  the  fixed  point  for  the  third  rib,  and  so  on.  The  scaleni  off^en  take  their 
fixed  point  upon  the  vertebrae,  and  then  assist  in  elevating  the  first  rib.  The  quadratus 
lumborum  depresses  the  last  rib,  which  may  then  serve  as  a  fixed  point  for  the  others 
during  expiration. 

The  levatores  act  very  effectually  in  raising  the  ribs ;  for,  being  attached  so  near  to 
the  fulcrum,  the  slightest  movement  produced  in  the  posterior  extremity  of  the  rib  be- 
comes very  sensible  at  the  other  end.  I  agree  with  Borelli  {De  Motu  Animal.,  torn,  ii-, 
p.  158),  that  the  intercostals  act  even  during  the  most  easy  respiration.  This  can  be 
observed  upon  our  own  persons,  and  also  in  individuals  in  deep  sleep.  The  ribs  will 
be  seen  distinctly  carried  outward,  and  the  sternum  raised. 

The  Triangularis  Sterni,  or  small  Jlnterior  Serratus. 
Dissection. — Divide  the  ribs  vertically  at  their  junction  with  the  cartilages,  and  tear 
off" the  plenra  with  the  fingers. 


224  .i/.(K.      :v  -'^X-    ^"  MYOLOGY.  '""^ 

The  triangularis  sterni  represents  the  levatores  costarum  in  front,  or,  rather,  the  ser- 
rati  postici,  with  this  difference,  that  it  occupies  the  internal  instead  of  the  external  sur- 
face of  the  thorax.  Like  them,  it  is  sen-ated.  It  arises  from  the  sides  of  the  posterior 
surface  of  the  sternum,  from  the  ensiform  cartilage  and  the  inner  ends  of  the  cartilages 
■  of  the  ribs.  From  this  origin  the  fleshy  fibres  proceed,  dividing  into  three,  four,  five,  and 
sometimes  six  digitations,  which  are  inserted  by  tendinous  fibres  into  the  posterior  sur- 
face and  borders  of  the  sixth,  fifth,  fourth,  third,  sometimes  of  the  second,  and  even  of 
the  first  costal  cartilages.  The  lower  fibres  pass  horizontally  and  parallel  to  the  upper 
fibres  of  the  transvcrsalis,  with  which  they  are  continuous.  The  succeeding  fibres  are 
directed  upward  and  outward,  proceeding  more  and  more  obliquely  upward  :  hence  the 
triangular  shape  of  the  muscle,  to  which  its  name  refers. 

Relations. — It  is  covered  by  the  sternum,  the  internal  intercostal  muscles,  and  the  cos- 
tal cartilages,  from  which  it  is  separated  by  the  manunary  vessels  and  some  lymphatic 
glands  ;  it  is  lined  internally  by  the  pleura,  and  rests  upon  the  diaphragm  below. 

Its  use  is  evidently  to  depress  the  costal  cartilages,  into  which  it  is  inserted,  or  to  op- 
pose their  elevation. 

Remarks  concerning  the  Intercostal  Muscles. — The  muscles  we  have  just  described,  viz., 
the  intercostals  and"  their  accessories,  are  essential  elements  in  the  construction  of  the 
chest ;  they  are  found  in  all  animals  possessed  of  a  thorax.  Their  use  is  to  dilate  and 
contract  this  cavity  in  its  antero-posterior  and  transverse  diameters.  The  first  rib,  be- 
ing Itxed  by  the  contraction  of  the  scaleni,  serves  as  a  fulcrum  for  the  agents  of  inspira- 
tion ;  and  the  last  rib,  when  fixed  by  the  quadratus  lumborum,  serves  the  same  purpose 
for  those  of  expiration ;  so  that  these  muscles,  whose  most  common  action  is  to  incline 
to  one  side  the  neck  and  the  loins,  do  not,  on  that  account,  act  the  less  u^jon  the  ribs. 
I  cannot,  by  any  means,  agree  with  Winslow,  who  denies  that  the  scaleni  have  any  ac- 
tion upon  the  ribs,  and  maintains  that  the  articulation  of  the  first  rib  with  the  first  dor- 
sal vertebra  is  intended  for  the  movement  of  the  vertebra  on  the  rib,  not  for  that  of  the 
rib  on  the  vertebra.     (Winslow,  Expos.  Anat.,  t.  ii.,  p.  360.) 


SUPERFICIAL  ANTERIOR  CERVICAL  REGION. 
TAe  Platysma  Myoides. — Sterno-cleido-mastoideus. 

The  Platysma  Myoides. 

Dissection. — Stretch  the  muscle  by  inclining  the  head  backward  and  placing  a  block 
under  the  shoulders  of  the  subject ;  make  a  horizontal  incision  through  the  skin  from  the 
angle  of  the  jaw  to  the  symphysis  menti,  another  from  the  symphysis  to  the  inner  end 
of  the  clavicle,  and  a  third  along  the  clavicle.  These  incisions  should  be  very  super- 
ficial, scarcely  dividing  the  entire  thickness  of  the  skin.  The  muscle  must  be  very  cau- 
tiously dissected  by  taking  care  to  commence  at  its  upper  part,  to  turn  the  edge  of  the 
scalpel  towards  the  skin,  and  to  follow  exactly  the  direction  of  the  fleshy  fibres  which 
pass  obliquely  downward  and  outward. 

The  platysma  myoides  (e,  fig.  109),  called  le  pcaucier  by  Winslow,  latissimus  colli  by  AI- 
binus,  is  a  broad,  very  thin,  and  irregularly-quadrilateral  muscle  lining  the  skin  at  the 
fore  part  of  the  neck,  and  adhering  to  it  like  the  cutaneous  muscles  of  the  lower  animals. 
It  extends  from  the  skin  covering  the  anterior  and  upper  part  of  the  thorax  to  the  side  ' 
of  the  face,  where  it  terminates  thus  :  at  the  base  of  the  lower  jaw,  at  the  commissure 
of  the  lips,  upon  the  masseter  muscle,  and  at  the  skin  of  the  face.  From  its  lower  at- 
tachment, which  is  almost  always  prolonged  as  far  as  the  shoulder,  and  loses  itself  in 
the  subcutaneous  cellular  tissue,  the  fibres  proceed  obliquely  upward  and  inward  ;  the 
pale  muscular  fasciculi  which  they  form  are  separated  from  each  other,  and  sometimes 
strengthened  by  additional  fasciculi  to  the  posterior  border  of  the  muscle  :  they  terminate 
in  the  following  manner  above  :  the  posterior  fibres  are  lost  under  the  skin  of  the  face 
near  the  masseter  muscle,  the  lower  end  of  which  they  cover ;  those  next  in  front  are 
partly  continuous  with  the  triangularis  oris,  and  partly  with  the  quadratus  menti ;  the 
anterior  fibres  terminate  at  the  external  oblique  line  of  the  lower  jaw,  and  the  most  in- 
ternal intersect  with  those  of  the  opposite  side.  The  posterior  fibres,  which  are  lost 
upon  the  skin  of  the  face,  are  the  rudiments  of  a  remarkable  fasciculus,  an  accessory  of 
the  platysma  found  in  some  subjects.  It  is  directed  obliquely  downward,  from  the  re- 
gion of  the  parotid  gland  to  the  angle  of  the  lips.  Santorini  described  it  under  the  name 
ofrisorius  novus. 

Relations. — These  two  muscles  occupy  the  whole  anterior  region  of  the  neck,  except- 
ing the  median  line,  where  they  leave  a  triangular  interval,  having  its  base  below,  and 
occupied  by  a  very  dense  fibrous  tissue,  forming  a  species  of  raph(5,  which  is  found  in  the 
median  line  throughout  the  body.  This  is  the  linea  alba  of  the  neck,  from  which  the  dif- 
ferent component  layers  of  the  cervical  fascia  take  their  origin. 

The  platysma  is  intimately  connected  with  the  skin,  but  it  does  not  adhere  equally 
throughout ;  it  is  united  closely  below,  but  much  more  loosely  above,  where  the  inter 


THE    STERNO-CLEIDO-MASTOIDEUS. 


225 


▼enmg  cellular  tissue  is  always  adipose,  and  capable  of  containing  a  large  quantity  of 
fat,  as  we  find  in  individuals  who  have  what  is  called  a  double  chin.  There  are  no  lym- 
phatic glands  between  this  muscle  and  the  skin ;  they  are  all  situated  beneath  the  mus- 
cle. The  relations  of  the  deep  surface  of  the  platysma  are  very  numerous.  It  covers 
the  supra  and  sub-hyoid,  and  the  supra-clavicular  regions,  being  separated  from  all  the 
structures  beneath  it  by  the  cervical  fascia,  to  which  it  is  united  by  loose  cellular  tissue, 
seldom  containing  any  fat.  If  we  examine  these  relations  in  detail,  we  find,  proceeding 
from  below  upward,  that  it  covers,  1.  The  clavicle,  the  pectoralis  major,  and  the  deltoid  ; 
2.  In  the  neck,  the  external  jugular  vein,  and  also  the  anterior  jugulars  where  they  ex- 
ist, the  superficial  cervical  plexus,  the  sterno-mastoid,  the  omo-hyoid,  the  sterno  or  cle- 
ido  hyoid,  the  digrastic,  and  the  mylo-hyoid  muscles,  the  sub-maxillary  gland,  and  the 
lymphatic  glands  at  the  base  of  the  jaw.  In  front  of  the  sterno-mastoid,  it  covers  the 
common  carotid  artery,  the  internal  jugular  vein,  and  the  pneumogastric  nerve  ;  behind 
the  sterno-mastoid,  it  covers  the  scaleni  muscles,  the  nerves  of  the  brachial  plexus,  and 
some  of  the  lower  nerves  of  the  cervical  plexus.  3.  In  the  face,  it  covers  the  external 
maxillary  or  facial  artery,  the  masseter  and  buccinator  muscles,  the  parotid  gland,  &c. 

Action. — The  platysma  is  the  most  distinctly  marked  vestige  in  the  human  body  of  the 
panniculus  carnosus  of  animals ;  and  it  can  produce  slight  wrinkles  in  the  skin  of  the 
neck.  Its  anterior  border,  especially  at  its  insertion  near  the  symphysis  menti,  is  the 
thickest  part  of  the  muscle,  and  therefore  projects  slightly  during  its  contraction.  It  is 
one  of  the  depressors  of  the  lower  jaw ;  it  also  depresses  the  lower  lip,  and,  slightly,  the 
commissure  of  the  lips.  It  therefore  assists  in  the  expression  of  melancholy  feelings, 
but  it  is  antagonized  by  the  accessory  portion,  which  draws  the  angle  of  the  lips  upward 
and  a  little  outward,  and  thus  concurs  in  the  expression  of  pleasurable  emotions ;  hence 
its  name,  risorius. 

The  Sterno-cleido-mastoideus. 

Dissection. — Divide  the  skin  and  the  platysma  from  the  mastoid  process  to  thewtop  of 
the  sternum,  in  an  oblique  line,  running  downward  and  forward ;  reflect  the  two  flaps, 
one  forward  and  the  other  backward,  taking  care  to  remove  at  the  same  time  the  strong 
fascia  which  covers  the  muscle.  In  order  to  obtain  a  good  view  of  the  superior  attach- 
ments, make  a  horizontal  incision  along  the  superior  semicircular  line  of  the  occipital  bone. 

The  sterno-cleido-Tnastoid  {b,  Jig.  113)  occupies  the  anterior  and  lateral  regions  of  the 
neck.  It  is  a  thick  muscle,  bifid  below,  and  narrower  in  the  middle  than  at  either  end. 
It  arises,  by  two  very  distinct  masses,  from  the  inner  end  of  the  clavicle,  and  from  the 
top  of  the  sternum  in  front  of  the  fourchette,  and  is  inserted  into  the  mastoid  process 
and  the  superior  semicircular  line  of  the  occipital  bone.  The  sternal  origin  consists  of 
a  tendon  prolonged  for  a  considerable  distance  in  front  of  the  fleshy  fibres.  The  clavic- 
ular origin  consists  of  very  distinct  parallel  ten-  pig.  113. 
dinous  fibres,  attached  to  the^  inner  side  of  the 
anterior  edge  and  upper  surface  of  the  clavicle, 
to  a  very  variable  extent,  an  important  fact  in 
surgical  anatomy.  There  is  often  a  considerable 
cellular  interval  between  these  two  origins ; 
sometimes  this  interval  scarcely  exists,  but,  in 
all  cases,  the  two  portions  of  the  muscle  can  be 
readily  separated.  From  this  double  origin  the 
fleshy  fibres  proceed,  forming  two  large  bundles, 
which  rfimain  distinct  for  some  time.  Many 
anatomists,  therefore,  Albinus  in  particular,  have 
considered  it  as  consisting  of  two  separate  mus- 
cles, which  they  describe  as  the  sterno-mastoid 
and  the  cleido-mastoid ;  a  division  that  is  sanc- 
tioned by  the  comparative  anatomy  of  this  mus- 
cle. The  sternal  portion  of  the  muscle  is  the 
larger,  and  passes  upward  and  outward ;  the  cla- 
vicular portion  proceeds  almost  vertically  upward, 
behind  the  other,  and  is  entirely  concealed  by  it 
at  the  middle  of  the  neck ;  the  two  portions  still 
remain  separate,  although  approximated ;  ulti- 
mately they  become  united,  and  are  inserted  into 
the  apex  and  anterior  surface  of  the  mastoid  pro- 
cess by  a  very  strong  tendon,  which  runs  for 
some  distance  along  the  anterior  border  of  the 
muscle,  and  also  into  the  two  external  thirds  of 
he  superior  semicircular  line  of  the  occipital  bone,  by  a  thin  aponeurosis.  The  direction- 
or  axis  of  the  sterno-mastoid  passes  obliquely  upward,  backward,  and  outward. 

The  relations  of  this  muscle  are  very  important.  Its  superficial  or  external  surface  is 
covered  bv  the  skin  and  platysma,  from  which  it  is  separated  by  the  external  jugulai' 

Fy 


226  MYOLOGY. 

vein,  and  the  branches  of  nerves,  constituting  what  is  improperly  termed  the  superficial 
cervical  plexus.  Its  deep  or  internal  surface  covers,  1.  The  sterno-clavicular  articulation  ; 
2.  All  the  muscles  of  the  sub-hyoid  region,  and  also  the  splenius,  the  levator  anguli  scap- 
ulae, the  digastricus,  and  the  scaleni ;  3.  The  accessory  nerve  of  Willis,  which  crosses 
beneath  its  superior  third,  the  pneumo-gastric  nerve,  the  great  sympathetic,  the  loop  of 
the  hypoglossal  nerve,  and  the  cervical  nerves ;  4.  The  internal  jugular  vein ;  5.  The 
lower  portion  of  the  common  carotid  artery.  Its  anterior  border  produces  a  ridge  under 
the  skin,  which  it  is  important  to  study,  because  the  first  incisions  for  hgature  of  the 
common  carotid,  and  for  oesophagotomy,  should  be  made  along  it.  The  parotid  gland 
rests  upon  the  upper  part  of  this  border,  which  is  separated  from  the  corresponding  bor- 
der of  the  muscle  of  the  opposite  side  by  a  triangular  interval,  of  which  the  apex  is  be- 
low and  the  base  above.  Its  posterior  border  forms  the  anterior  limits  of  the  lateral  tri- 
angle of  the  neck,  which  is  bounded  behind  by  the  external  margin  of  the  trapezius,  and 
below  by  the  clavicle. 

Action. — When  the  sterno-cleido-mastoid  of  one  side  acts  alone,  it  flexes  the  head,  in- 
clines it  to  its  own  side,  and  rotates  it  so  that  the  face  is  turned  to  the  opposite  side.  It 
is,  therefore,  both  a  flexor  and  a  rotator  of  the  head.  When  both  muscles  act  together, 
they  flex  the  head  directly  upon  the  neck,  and  the  neck  upon  the  chest.  Their  action  is 
particularly  manifested  in  an  attempt  to  raise  the  head  while  lying  upon  the  back.  Still, 
there  is  a  position  in  which  this  muscle  may  become  an  extensor  of  the  head,  viz.,  when 
it  is  thrown  very  far  backward ;  and  this  effect  is  owing  to  the  nature  of  the  upper  inser- 
tion, which  is  situated  somewhat  behind  the  fulcrum  of  the  lever  represented  by  the  head. 

This  muscle  affords  one  of  the  most  remarkable  examples  of  the  co-operation  or  si- 
multaneous action  of  several  muscles,  in  order  to  give  effect  to  the  action  of  one.  Thus, 
in  order  that  the  sterno-cleido-mastoid  may  act  most  advantageously  upon  the  head,  it 
becomes  necessary  that  the  sternum,  being  the  fixed  point,  should  be  maintained  as  im- 
movable as  possible,  and  this  can  only  be  effected  by  the  contraction  of  the  recti  muscles 
of  the  abdomen.  These  latter,  in  their  turn,  require  a  fixed  point  at  the  pelvis,  and  this 
renders  necessary  the  contraction  of  the  glutaei,  the  semi-tendinosus,  the  semi-mem- 
branosus,  and  biceps  femoris  on  either  side  ;  and,  lastly,  for  the  action  of  these,  the  legs 
require  to  be  fixed  by  means  of  their  extensor  muscles. 

This  remarkable  simultaneous  contraction  of  so  many  muscles,  necessary  for  the  ac- 
tion of  but  one,  has  been  extremely  well  illustrated  by  Winslow.  It  has  many  impor- 
tant results  both  in  physiology  and  in  pathology. 


MUSCLES  OF  THE  INFRA-HYOID  REGION. 

The  Stcrno-hyoideus. — Scapula-  or  Omo-hyoideus. — Sterno-thyroideus. — Thyro-hyoideus. 

The  muscles  of  the  infra-hyoid  region  are  four  in  number«on  each  side,  viz.,  the  sterno, 
or,  rather,  cleido-hyoid,  the  omo-hyoid,  and  the  sterno-thyroid,  which  is  continuous  above 
witli  the  fourth  muscle,  viz.,  the  thyro-hyoid. 

The  Sterno-hyoideus. 

Dissection. — This  is  extremely  easy,  and  is  the  same  for  all  the  muscles  of  this  region. 
Tlie  only  caution  necessary  is,  that  the  clavicular  and  sternal  attachments  of  these  mus- 
cles should  be  studied  from  their  posterior  aspect  only,  and  that  the  trapezius  must  be 
removed  in  order  to  expose  the  scapular  attachments  of  the  omo-hyoid. 

The  sterno-hyoid  [I,  figs.  113  and  114)  is  a  flat,  thin,  riband-like  muscle,  which  is  some- 
times double  on  each  side.  It  arises  from  the  inner  end  of  the  clavicle,  and  is  inserted 
into  the  os  hyoides.  Its  inferior  attachment  is  liable  to  some  variations  ;  most  conmion- 
ly  it  is  connected  with  the  back  part  of  the  inner  extremity  of  the  clavicle  and  with  the 
inter-articular  cartilage  ;  sometimes  with  the  outer  side  of  that  extremity  ;  and  sometimes 
with  the  circumference  of  the  clavicular  surface  of  the  sternum.  From  this  origin  the 
fleshy  fibres  proceed  parallel  to  each  other,  upward  and  inward,  to  be  inserted  by  short 
tendinous  fibres  into  the  lower  edge  of  the  body  of  the  os  hyoides  on  the  side  of  the 
median  line,  and  to  the  inside  of  the  omo-hyoid,  with  which  it  is  often  blended.  Imme- 
diately above  the  clavicle  this  muscle  is  often  divided  by  an  aponeurotic  intersection, 
which  is  united  to  that  of  the  opposite  side,  and  forms,  as  it  were,  a  transverse  bridle. 

Relations. — It  is  covered  by  the  platysma,  the  stemo-mastoid,  and  the  cervical  fascia. 
It  covers  the  deep-seated  muscles,  the  thyroid  body,  the  crico-thyroid  and  thjTO-hyoid 
membranes,  from  which  it  is  often  separated  by  a  bursa  mucosa,  the  crico-thyroid  mus- 
cle, and  the  superior  thyroid  artery.  The  inner  edges  of  the  two  sterno-hyoid  muscles 
are  generally  separated  by  a  fibrous  raphe,  but  they  are  sometimes  blended  together,  and 
thus  render  the  operation  of  tracheotomy  more  difficult.  This  impediment  may,  how- 
ever, be  overcome  by  keeping  accurately  in  the  median  line. 

The  Scapulo-  or  Omo-hyoideua. 
This  muscle  (coraco-hyoideus,  Albinus,  m  m,  figs.  113  and  114)  is  longer  and  more 


THE    STERNO-THYROIDEUS    AND    THYRO-HYOIDEUS.  227 

slender  than  the  preceding ;  it  is  a  digastric  reflected  muscle,  composed  of  two  small 
fleshy  bellies,  united  by  an  intermediate  tendon.  It  arises  from  the  superior  border  of 
the  scapula  behind  the  coracoid  notch,  over  an  extent  varying  from  a  few  lines  to  an 
inch,  and  is  inserted  into  the  lower  part  of  the  body  of  the  os  hyoides,  externally  to  the 
sterno-hyoid.  From  its  origin,  which  is  sometimes  tendinous,  it  proceeds  for  a  variable 
distance  behind  and  parallel  to  the  clavicle,  and  is  then  reflected  upward  and  inward,  at 
an  obtuse  angle.  At  the  point  of  reflection  it  becomes  entirely  or  partially  tendinous, 
and  gives  origin  to  another  fleshy  bundle  larger  than  the  former,  which  is  inserted  into 
the  OS  hyoides. 

The  angular  direction  of  this  muscle  is  maintained  by  means  of  an  aponeurosis,  first 
described  by  Soemmering,  which  extends  between  the  inner  borders  of  the  two  muscles, 
and  is  fixed  to  the  clavicle  :  it  is  one  of  the  layers  of  the  cervical  fascia,  an  important 
structure,  to  be  again  alluded  to  hereafter,  and  of  which  the  omo-hyoid  muscles  are  ten- 
sors. These  muscles  eire  occasionally  wanting ;  sometimes  they  are  double.  In  one 
case  of  this  kind  the  accessory  muscle  was  larger  than  the  normal  one,  and  arose  from 
the  upper  and  internal  angle  of  the  scapula. 

Relations. — This  small  muscle,  before  reaching  the  sub-hyoid  region,  traverses  two 
others,  the  supra-clavicular  and  the  stemo-mastoid.  It  is  covered  by  the  trapezius,  the 
subclavius,  the  clavicle,  the  platysma,  the  stemo-mastoid,  and  the  skin ;  it  covers  the 
scaleni,  the  brachial  plexus,  the  internal  jugular  vein,  and  the  common  carotid  artery, 
and  it  is  in  contact  with  the  outer  border  of  the  sterno-hyoid  muscle. 

The  Sterno-thyroideus. 

The  sterno-thyroid  (w.  Jig.  1 14)  closely  corresponds  with  the  sterno-hyoid,  from  which 
it  differs  only  in  being  shorter  and  broader.  It  extends  from  the  posterior  surface  of  the 
sternum  to  the  thyroid  cartilage.  It  arises  from  the  sternum  opposite  the  first  rib  ;  it  is 
often  blended  with  its  fellow,  so  that  their  origins  form  a  line  reaching  the  entire  breadth  of 
the  sternum,  and  often  to  the  edges  and  posterior  surface  of  the  cartilage  of  the  first  rib. 

From  this  origin  the  fleshy  fibres  proceed  directly  upward  parallel  to  each  other,  and 
are  inserted  into  the  thyroid  cartilage  by  a  tendinous  arch  running  obliquely  downward 
and  inward,  which  embraces  the  thyro-hyoid  muscle,  and  is  attached  by  its  extremities 
to  two  very  prominent  tubercles  on  the  external  surface  of  the  cartilage.  It  is  some- 
times continued  as  far  as  the  os  hyoides  by  a  small  lateral  prolongation,  and  at  other 
times  it  is  continuous  with  the  thyro-hyoid.  The  sterno-thyroid  is  interrupted  by  a  ten- 
dinous intersection  analogous  to  those  of  the  rectus  abdominis.  It  is  not  uncommon  to 
find  the  two  sterno-thyroid  muscles  united  together  by  an  intervening  aponeurosis  shaped 
like  the  letter  V,  opening  upward,  and  corresponding  to  the  fourchette  of  the  sternum. 

Relations. — It  is  covered  by  the  sterno-hyoid  and  omo-hyoid  muscles,  and  it  covers  the 
trachea,  the  lower  part  of  the  subclavian  and  internal  jugular  veins,  the  common  carotid 
artery,  and  the  arteria  innominata  on  the  right  side,  the  thyroid  body  and  the  thyroid 
vessels.  The  middle  thyroid  vein  runs  along  its  inner  border,  an  important  relation  in 
regard  to  the  operation  of  tracheotomy. 

The  Thyro-hyoideus. 

This  is  a  small  quadrilateral  muscle  (hyo-thyroideus,  Albinus),  which  may  be  consider- 
ed a  continuation  of  the  stemo-thjToid  (^o,figs.  113  and  114).  It  arises  from  the  oblique 
line,  and  the  tubercles  of  the  thyroid  cartilage,  where  it  is  embraced  by  the  tendinous 
arch  of  the  preceding  muscle,  passes  vertically  upward,  and  is  inserted  into  the  posterioi 
surface  of  the  body  and  part  of  the  great  cornu  of  the  os  hyoides. 

Relations. — It  is  covered  by  the  two  muscles  of  the  superficial  layer,  and  covers  the 
thyroid  cartilage,  and  the  th3TO-hyoid  membrane. 

Action  of  the  Muscles  of  the  Sub-hyoid  Region. — These  muscles  are  the  most  simple, 
both  in  structure  and  in  action  :  they  all  concur  in  depressing  the  lower  jaw  ;  but  if  the 
lower  jaw  is  ficxed,  they  produce  flexion  of  the  head.  The  fixed  points  of  all  are  below, 
viz.,  at  the  sternum  on  the  inside,  at  the  clavicle  in  the  middle,  and  at  the  scapula  on  the 
outside.  This  arrangement  not  only  bestows  particular  uses  upon  each,  but  renders  the 
common  action  of  all  more  certain.  Thus,  the  omo-hyoid,  at  the  same  time  that  it  de- 
presses the  03  hyoides,  carries  it  backward  and  towards  its  own  side.  Wliere  the  two 
omo-hyoid  muscles  act  together,  the  os  hyoides  is  directly  depressed,  and  forced  back- 
ward against  the  vertebral  column.  The  sterno-hyoid  and  the  sterno-thyroid,  prolonged  by 
the  thyro-hyoid,  draw  the  os  hyoides  directly  downward.  The  principal  use  of  the  thyro- 
hyoid is,  to  move  the  os  hyoides  upon  the  thyroid  cartilage,  in  which  movements  the  upper 
part  of  the  cartilage  is  carried  behind  the  os  hyoides,  the  curve  described  by  which  is  al- 
ways greater  than  that  formed  by  the  cartilage.  The  muscles  of  the  sub-hyoid  region  nev- 
er eissume  as  their  movable  point  3  either  their  sternal,  clavicular,  or  scapular  attachments 


^'P^^^IP^'^F*^ 


228 


MYOLOGY. 


MUSCLES  OF  THE  SUPRA-HYOID  REGION. 

The  Digastricus. — Stylo-hyoideus. — Mylo-hyoideus. — Genio-hyoideus. — Their  Action. 
The  muscles  of  this  region,  taken  in  the  order  of  super-imposition,  are  the  digastric, 
the  stylo-hyoid,  the  mylo-hyoid,  and  the  genio-hyoid. 

The  Digastricus. 

Distection. Remove  the  platysma,  reflect  the  mastoid  insertion  of  the  stemo-mastoid ; 

Pig^  114.  detach  and  raise  the  sub-maxillary 

and  the  lower  extremity  of  the  pa- 
rotid gland. 

The  digastric  muscle  (biventer 
mjixillae  inferioris,  Albinus,p  p,figs. 
113  and  114),  so  named  because  it 
consists  of  two  fleshy  bellies,  united 
by  an  intermediate  tendon,  reaches 
the  whole  extent  of  the  supra-hyoid 
region,  from  behind  forward.  It  is, 
in  some  respects,  the  type  of  digas- 
tric muscles.  It  is  curved  upon  it- 
self, forming  the  arc  of  a  circle,  with 
the  concavity  directed  upward. 

It  arises  from  the  digastric  groove 
in  the  mastoid  process,  and  from  the 
anterior  edge  of  that  process,  in  front 
of  the  sterno-mastoid  ;  it  it  inserted 
into  the  side  of  the  symphysis  menti, 
below  the  sub-mental  tubercles,  into 
the  whole  extent  of  the  digastric  fos- 
sa. It  is  also  attached  to  the  os  hy- 
oides  by  means  of  an  aponeurotic  ex- 
pansion. 

Its  origin  from  the  mastoid  pro- 
cess is  partly  fleshy  and  partly  ten- 
dinous, the  tendon  being  prolonged 
for  some  distance  upon  the  upper  border  of  the  muscle.  The  fusiform  fleshy  belly  pro- 
duced in  this  manner  passes  forward,  inward,  and  downward,  into  the  interior  of  a  sort 
of  fibrous  cone,  forming  the  commencement  of  the  intermediate  tendon.  This  tendon, 
which  is  about  two  inches  in  length,  follows  at  first  the  direction  of  the  muscle,  almost 
always  perforates  the  stylo-hyoid  muscle,  and  is  then  received  into  a  fibrous  ring  attach- 
ed to  the  OS  hyoides,  and  lined  by  a  synovial  capsule.  This  fibrous  ring  is  often  wanting. 
A  broad  aponeurotic  expansion  proceeds  from  the  intermediate  tendon,  and  is  fixed  to  the 
OS  hyoides.  When  this  is  united  to  the  corresponding  structure  on  the  opposite  side, 
they  form  a  very  strong,  triangular  aponeurosis,  called  the  supra-hyoid  aponeurosis,  which 
occupies  the  interval  between  the  two  muscles,  and  serves  as  a  kind  of  floor  for  the  other 
muscles  of  the  supra-hyoid  region.  After  having  passed  through  the  fibrous  ring,  the  ten- 
don changes  its  direction,  and  is  reflected  at  an  obtuse  angle  upward  and  forward,  to  ter- 
minate in  another  tendinous  cone.  From  the  interior  of  this  cone  the  fleshy  fibres  of  the 
anterior  belly  take  their  origin.  This  belly  is  not  so  strong  as  the  posterior,  and  is  insert- 
ed by  separate  tendons,  sometimes  intersecting  those  of  the  opposite  side,  into  the  whole 
extent  of  the  digastric  fossa,  below  the  sub-mental  tubercles.  Some  fibres  are  often 
blended  with  those  of  the  mylo-hyoid.  It  is  not  uncommon  to  see  a  small  fasciculus 
arising  from  the  os  hyoides,  and  strengthening  the  anterior  belly.  The  two  anterior  bel- 
lies are  sometimes  united  by  a  raphe,  and  by  a  small  transverse  fibrous  bundle. 

Relations. — It  is  covered  by  the  platysma  and  sterno-mastoid,  the  parotid  and  the  sub- 
maxillary glands,  the  latter  of  which  it  embraces  by  the  concavity  of  its  upper  border :  it 
covers  the  muscles  which  arise  from  the  styloid  process,  the  mylo-hyoid  muscle,  the  in- 
ternal jugular  vein,  the  external  carotid  artery,  and  its  labial  and  lingual  branches,  the 
mternal  carotid,  and  the  hypo-glossal  nerve,  which  lies  parallel  with,  and  beneath  the 
intermediate  tendon  of  the  muscle. 

Its  action  is  very  complicated  :  when  the  posterior  belly  contracts  alone,  the  os  hyoides 
is  carried  backward  and  upward ;  the  anterior  belly  carries  it  forward,  and  also  upward. 
When  the  two  bodies  of  the  muscle  contract  at  the  same  time,  these  opposite  effects  are 
destroyed,  and  the  os  hyoides  is  carried  directly  upward.  In  all  these  motions,  the  low- 
er jaw  must  be  fixed.  If  the  os  hyoides  is  fixed,  the  posterior  belly  becomes  a  depressoi 
of  the  jaw,  on  account  of  the  reflection  of  the  muscle  ;  the  anterior  and  the  posterior  bel- 
lies can  incline  the  head  backward,  but  this  inclination  of  the  head  backward  during  mas- 
tication, and  when  the  jaws  are  separated,  depends  on  the  action  of  the  posterior  exten- 


THE    STYLO,    MYLO,   AND    GENIO    HYOIDES.  229 

BOr  muscles  of  the  neck ;  leistly,  the  anterior  belly  of  the  digastric  is  the  tensor  of  the 
supra-hyoid  fascia. 

The  Stylo-hyoideus. 

Dissection. — Detach  the  posterior  belly  of  the  digastric.  This  is  a  small  and  very  thin 
muscle  {q,fig.  114  ;  ^  q,fig^-  ^^'^  ^^^  ^^'^),  like  all  those  which  are  attached  to  the  sty- 
loid process. 

It  arises  from  the  back  of  the  styloid  process,  at  a  short  distance  from  the  apex,  and  oppo- 
site the  insertion  of  the  stylo-maxillary  ligament.  This  origin  consists  of  a  small  tendon, 
which  terminates  in  a  fibrous  cone,  from  the  interior  of  which  the  fleshy  fibres  commence. 
These  proceed  downward,  forward,  and  inward,  and  form  a  bundle,  which  is  almost  al- 
ways perforated  by  the  tendon  of  the  digastric.  Occasionally  the  fibres  pass  only  in  front 
of  that  tendon.  They  are  iiiserted  into  the  body  of  the  os  hyoides,  at  a  short  distance 
from  the  median  line.  Sometimes  the  tendon  of  insertion  is  reflected  upon  itself,  and 
forms  the  pulley  for  the  digastric. 

Relations. — It  is  covered  by  the  posterior  belly  of  the  digastric,  and  has  the  same  re- 
lations as  that  muscle.  It  is  not  uncommon  to  find  a  second  stylo-hyoid  muscle,  ex- 
tending from  the  styloid  process  to  the  little  cornu  of  the  os  hyoides.  This  muscle  takes 
the  place  of  the  stylo-maxillary  ligament ;  it  was  described  by  Santorini  under  the  name 
of  the  stylo-hyoideus  iwvus,  and  was  noticed  also  by  Albinus.* 

The  Mylo-hyoideus. 

Dissection. — Detach  the  anterior  belly  of  the  digastric  at  its  maxillary  insertion  ;  dis- 
sect the  sub-maxillary  gland,  and  turn  it  outward. 

This  muscle  {r,  figs.  113  and  114),  situated  immediately  below,  i.  e.,  deeper  (as  re- 
gards the  surface)  than  the  anterior  belly  of  the  digastric,  is  thin  and  quadrilateral.  It 
arises  from  the  whole  extent  of  the  mylo-hyoid  line,  from  opposite  the  last  molar  to  the 
symphysis  menti,  by  short  aponeurotic  fibres.  The  fleshy  fibres  arising  from  these  pass 
in  different  directions :  the  internal  (or  anterior),  very  short,  proceed  inward  to  a  median 
fibrous  raphe,  which  traverses  the  whole  supra-hyoid  region  ;  the  external  (or  posterior) 
pass  much  less  obliquely  to  the  upper  part  of  the  body  of  the  os  hyoides.  The  median 
raphe  is  sometimes  wanting,  and  the  muscular  fibres  of  the  opposite  sides  are  continuous 
with  each  other.  Some  of  the  fibres  are  often  lost  in  the  digastric,  and  are  even  contin- 
uous with  the  sterno-hyoid.  The  two  mylo-hyoid  muscles  may,  with  great  propriety,  be 
regarded  as  a  single  muscle,  divided  by  a  tendinous  intersection  in  the  median  line. 

Relations. — It  is  covered  by  the  anterior  belly  of  the  digastric,  the  supra-hyoid  fascia, 
the  platysma,  and  the  sub-maxillary  gland ;  and  it  covers  the  genio-hyoid,  the  hyo-glos- 
sus,  and  stylo-glossus  muscles,  the  lingual  and  hypo-glossal  nerves,  the  Whartonian 
duct,  the  sublingual  gland,  and  the  buccal  mucous  membrane. 

The  Genio-hyoideus. 

This  muscle  {s,fig.  114,  143,  147)  is  situated  below,  i.  e.,  deeper  than  the  preceding, 
which  must  be  divided  very  carefully,  in  order  to  avoid  raising  the  two  together.  It  is  a 
small,  round,  fleshy  bundle,  described  by  anatomists  as  consisting  of  two  very  minute 
muscles,  separated  from  each  other  by  an  extremely  delicate  cellular  tissue.  Sometimes 
it  is  impossible  to  separate  them;  at  other  times  the  two  bundles  are  very  distinct 
They  arise  from  the  inferior  sub-mental  tubercle,  and  proceed  downward  and  backward, 
to  be  inserted  into  the  upper  part  of  the  os  hyoides. 

Relations. — ^They  are  covered  by  the  mylo-hyoids,  and  cover  the  hyo-glossal  muscles. 

Actions  of  the  Muscles  of  the  Supra-hyoid  Region. 

These  are  of  two  kinds,  relating  to  the  depression  of  the  lower  jaw,  and  to  the  eleva- 
tion of  the  OS  hyoides. 

The  OS  hyoides  being  fixed  by  the  muscles  of  the  sub-hyoid  region,  all  the  supra-hyoid 
muscles,  with  the  exception  of  the  stylo-hyoids,  depress  the  lower  jaw ;  and  it  should 
be  observed  that  they  are  situated  in  the  most  favourable  manner  for  this  purpose  ;  for, 
on  the  one  hand,  they  are  almost  perpendicular  to  the  lever,  and,  on  the  other,  they  are 
attached  as  far  as  possible  from  the  fulcrum.  The  obliquity  of  their  direction  has  also 
this  advantage,  that  the  lower  jaw  is  carried  backward  as  well  as  depressed,  and  thus 
the  orifice  of  the  mouth  is  greatly  increased  in  size. 

But  the  most  important  action  of  these  muscles  relates  to  the  elevation  of  the  os  hy- 
oides. This  elevation  is  an  indispensable  element  in  the  act  of  deglutition,  and  also  in 
the  protrusion  of  the  tongue.  Thus,  the  os  hyoides  is  carried  upward  and  backward  by 
the  stylo-hyoid  muscles  and  by  the  posterior  belly  of  the  digastric,  upward  and  forward 
by  the  anterior  belly  of  the  digastric  and  by  the  mylo-  and  genio-hyoids,  and  directly  up- 
ward by  the  combined  action  of  all  these  muscles.  The  base  of  the  tongue,  of  which 
the  os  hyoides  constitutes,  in  some  degree,  the  framework,  is  associated  with  it  in  all 

*  Albinus  termed  it  stylo-hyoideus  alter. 


MYOLOGY. 

these  movements,  which  take  place  at  different  periods  of  deglutition :  thus,  the  move- 
ment upward  and  forward  is  effected  during  the  period  when  the  alimentary  mass  is 
driven  from  the  cavity  of  the  mouth  into  the  pharynx,  which  enlarges  for  its  reception. 
The  direct  elevation  takes  place  when  the  mass  is  passing,  and  the  movement  upward 
and  backward  occurs  after  it  has  passed,  so  as  to  prevent  its  return  into  the  mouth. 
When  the  lower  jaw  is  fixed  against  the  upper,  and  the  os  hyoides  is  also  fixed  by  the 
sub-hyoid  muscles,  the  muscles  of  the  supra-hyoid  region  assist  in  flexing  the  head. 
Lastly,  the  os  hyoides  is  elevated  during  the  production  of  acute,  and  depressed  during 
that  of  grave,  vocal  tones. 


MUSCLES  OF  THE  CRANIAL  REGION. 
Occipito-froTttalis .  — A uricular  Muscles . 
The  muscles  of  the  cranial  region  are  the  occipito-frontalis  and  the  auricular  muscles. 

The  Occipito-frontalis. 

Dissection. — Shave  the  head,  and  make  a  horizontal  incision  above  the  superciliary 
arch  ;  make  a  second  incision  in  a  vertical  direction  from  before  backward,  and  reaching 
from  the  former  to  the  superior  semicircular  line  of  the  occipital  bone  ;  be  very  careful 
not  to  dissect  away  the  epicranial  aponeurosis,  nor  the  fibres  of  the  muscle  ;  commence 
the  dissection  at  the  fleshy  fibres,  which  adhere  less  intimately  to  the  skin  than  the 
aponeurosis. 

The  occipito-frontalis  (epicranius,  Albinus,  a'  a',  jig.  113)  is  sometimes  regarded  as  one 
muscle  with  two  bellies  ;  sometimes  as  a  combination  of  two  separate  muscles,  the  oc- 
cipital and  the  frontal.  It  covers  the  roof  of  the  scull.  We  shall  describe  the  occipital  and 
frontal  portions  only ;  the  aponeurosis  will  be  elsewhere  noticed.   (Vide  Aponeurology.) 

1.  The  occipital  portion,  or  occipital  muscle,  covers  a  great  part  of  the  occipital  bone, 
and  is  situated  over  the  superior  occipital  protuberance.  It  is  thin  and  quadrilateral. 
It  arises  from  the  two  external  thirds  of  the  superior  semicircular  line,  and  from  the 
neighbouring  part  of  the  mastoid  process  of  the  temporal  bone,  and  is  inserted  into  the 
posterior  border  of  the  cranial  aponeurosis,  of  which  it  may  be  regarded  as  the  tensor. 
The  occipital  attachment  is  composed  of  tendinous  fibres,  the  fleshy  fibres  proceeding 
from  which  pass  upward  in  a  parallel  direction,  and,  after  a  short  course,  terminate  in 
the  aponeurosis. 

2.  The  frontal  portion,  or  frontal  muscle,  is  placed  at  the  front  of  the  cranium  ;  it  is 
thin,  and  irregularly  quadrilateral,  like  the  preceding.  It  is  attached  above  to  the  cranial 
aponeurosis,  and  terminates  below  in  the  following  manner :  1.  The  internal  or  median 
fibres  are  prolonged  into  a  fleshy  band,  which  constitutes  the  pyramidalis  nasi ;  2.  The 
fibres  next  on  the  outside  are  continuous  with  those  of  another  muscle,  viz.,  the  levator 
labii  superioris  alaeque  nasi — ^to  the  outside  of  these  fibres,  the  muscle  is  attached  to  the 
internal  orbital  process ;  3.  The  greater  number  of  the  fibres  are  blended  with  those  of 
the  orbicularis  palpebrarum.  The  upper  border  of  the  muscle,  which  is  attached  to  the 
aponeurosis,  forms  a  semicircular  line,  that,  in  many  individu^^,  causes  a  projection  un- 
der the  skin. 

Relations. — Tlie  occipito-frontalis  covers  the  roof  of  the  scull ;  hence  the  name  of  epi- 
cranius (Albinus).  It  rests  upon  the  pericranium  (the  periosteum  of  the  cranial  bones), 
being  separated  from  it  by  a  quantity  of  moist  cellular  tissue,  which  admits  of  a  consid- 
erable degree  of  mobility  of  the  integuments,  and  is  so  elastic  that  it  returns  to  its  origi- 
nal situation  after  being  displaced  by  any  movements  of  the  hairy  scalp.  The  super- 
ficial surface  of  this  muscle  is  covered  by  the  skin,  and  is  united  to  it  by  a  very  dense, 
almost  fibrous  cellular  tissue,  in  which  are  ramified  the  numerous  vessels  and  nerves  of 
the  cranial  integuments. 

Action. — The  occipital  portion  is  a  tensor  of  the  epicranial  aponeurosis,  which,  when 
stretched,  affords  a  fixed  point  for  the  frontal  portion.  This  latter  raises  the  upper  half 
of  the  orbicularis  palpebrarum,  elevates  the  eyebrows  and  the  skin  over  the  root  of  the 
nose,  and  has  a  great  effect  in  the  expression  of  emotions  of  delight.  This  muscle  pro- 
duces the  transverse  wrinkles  on  the  forehead,  which  give  to  the  countenance  of  indi- 
viduals who  are  habitually  gay  a  peculiar  expression,  that  is  often  imitated  by  painters. 
These  transverse  wrinkles  do  not  extend  over  the  triangular  interval,  which  separates 
the  two  fleshy  bellies  of  the  muscle  in  the  centre  of  the  forehead. 

The  occipito-frontalis  must  be  regarded  as  an  elevator  of  the  upper  eyelids  ;  it  is  blend- 
ed with  the  orbicularis  palpebrarum  in  the  same  manner  as  the  labial  muscles  with  the 
orbicularis  oris.  In  this  respect  the  occipito-frontalis  is  assisted  by  the  levator  palpe- 
hrse  superioris,  and  antagonized  by  the  corrugator  supercilii  and  orbicularis  palpebrarum. 
Can  this  muscle  erect  the  hairs  on  the  head  1  It  is  certain  that  it  can  move  the  entire 
hairy  scalp,  for  many  individuals  are  able  to  do  this  at  will ;  but  it  appears  to  me  that 
the  expression,  the  hairs  stand  on  end,  as  regards  man,  is  merely  figurative,  and  is  de- 
rived from  what  occurs  in  the  lower  animals,  in  which  this  erection  of  the  hair  is  very 


THE   AURICULAR   MUSCLES,   ETC.  1281 

manifest.    Perhaps,  however,  the  skin  itself  may  produce  this  effect  by  the  same  mech- 
anism as  that  which  gives  rise  to  goose  skin. 

The  Auricular  Muscles. 

Dissection. — Be  very  careful  in  dissecting  the  superior  and  anterior  auricular  muscles, 
which  are  extremely  thin,  and  consist  only  of  a  few  colourless  fibres.  To  render  them 
as  tense  and  prominent  as  possible,  it  is  necessary  to  draw  the  ear  away  from  the  mus- 
cle to  De  examined. 

All  these  muscles  are  rudimentary  in  man,  in  whom  the  external  ear  is  almost  im- 
movable. They  may  all  be  considered  as  dilators  of  the  auditory  meatus,  to  which  there 
is  no  constrictor  or  sphincter  in  the  human  subject :  certain  animals,  however,  possess- 
ing a  very  delicate  sense  of  hearing,  have  constrictor  muscles,  which  draw  together  and 
move  the  different  pieces  forming  the  cartilaginous  portion  of  this  canal. 

The  auricular  muscles  are  three  in  number  :  a  superior,  an  anterior,  jmd  a  posterior. 

The  Auricularis  Superior. 

This  muscle,  which  is  extremely  thin  and  of  a  triangular  form  (b',Jig.  1 13),  oocupies  the 
temporal  fossa.  It  arises  from  the  external  border  of  the  epicranial  aponeurosis,  of  which 
it  seems  to  be  a  dependance  ,  from  this  origin  its  fibres  converge,  and  are  inserted  into  the 
upper  part  of  the  concha.    It  is  covered  by  the  skin,  and  lies  upon  the  temporal  fascia. 

Action. — To  raise  the  ear  (attollens  auriculam,  Albinus). 

The  Auricularis  Anterior. 

This  muscle  (c'.  Jig.  1 13)  is  still  thinner  and  less  marked  than  the  preceding,  with 
which  it  is  continuous.  It  is  also  triangular,  and  arises  from  the  outer  edge  of  the  oc- 
cipito-frontalis  and  the  cellular  tissue  covering  the  zygomatic  region ;  the  fibres  con- 
verge from  their  origin,  and  are  inserted  into  the  front  of  the  helix.  It  is  covered  by  the 
skin,  and  lies  upon  the  temporal  fascia,  from  which  it  is  separated  by  the  temporal  artery 
and  vein. 

Action. — To  draw  the  auricle  forward  and  upward  (anterior  auriculae,  Albinus). 

The  Auricularis  Posterior. 

This  muscle  {d',fig.  113)  is  much  more  decidely  marked  than  the  preceding,  and  is 
composed  of  two  or  three  distinct  fleshy  fasciculi  (tres  retrahentes  auriculam,  Albinus), 
which  extend  from  the  base  of  the  mastoid  process,  and  sometimes  also  from  the  occipi- 
tal bone  to  the  lower  part  of  the  concha. 

Action. — To  draw  the  aiu-icle  backward. 


MUSCLES  OF  THE  FACE. 


All  the  muscles  of  the  face  are  arranged  in  groups  around  its  several  openings,  and 
may  be  classed  either  as  dilators  or  constrictors.  The  nostrils  alone  have  no  constrictors. 

The  eyelids  must  be  opened  and  closed  entire,  without  the  production  of  any  folds ; 
the  nostrils  must  remain  constantly  open,  for  the  skin  around  these  orifices  has  within  it 
a  corresponding  lamina  of  cartilage,  which  gives  it  the  necessary  tension,  strength,  and 
elasticity,  and  into  which  the  muscles  are  inserted.  There  is  no  such  arrangement  at 
the  orifice  of  the  mouth,  the  muscles  being  there  inserted  into  other  muscles. 

From  the  three  openings  around  which  the  muscles  of  the  face  are  grouped,  these  may 
be  arranged  into  three  distinct  regions,  viz.,  the  palpebral,  the  nasal,  and  the  buccal. 

MCSCLES    OF   THE    PALPEBRAL    ReGION. 

Orbicularis  Palpebrarum. — Super ciliaris. — Levator  Palpebra  Superioris. 
The  muscles  of  the  eyelids  are  divided  into  constrictors  and  dilators.    There  is  one 
constrictor,  viz.,  the  orbicularis  palpebrarum,  to  which  the  corrugator  supercilii  is  an  ac- 
cessory ;  there  is  also  one  elevator,  viz.,  the  levator  palpebrae  superioris. 

The  Orbicularis  Palpebrarum. 

Dissection. — ^Make  an  elliptical  incision  through  the  skin  round  the  base  of  the  orbit ; 
dissect  successively  the  upper  and  lower  half  of  the  muscle,  proceeding  from  the  adhe- 
rent towards  the  free  border  of  each  eyelid.  It  is  of  more  importance  here  than  in  any 
other  situation  to  dissect  the  skin  parallel  to  the  fleshy  fibres.  When  the  external  sur- 
face of  the  muscle  has  been  studied,  detach  it  carefully  from  the  subjacent  parts,  and  re- 
flect it  inward. 

The  orbicularis  palpebrarum  {e',fig.  113)  forms  an  elliptical  zone  of  variable  size  round 
the  eyelids,  and  also  an  extremely  thin  layer  upon  them.  It  is  a  sphincter,  and,  like  all 
muscles  of  this  kind,  is  composed  of  circular  fibres  ;  but,  as  a  special  exception,  it  is  also 
provided  with  a  remarkable  tendon  of  origin,  named  the  straight  tendon  of  the  orbicularis ; 
this  is  about  two  hues  in  length  and  half  a  line  in  breadth,  arises  from  the  ascending  pro- 
cess of  the  superior  maxilla,  anteriorly  to  the  lachrymal  groove,  and  passes  in  front  of 


2JK5  MYOLOGY. 

the  lachrymal  sac,  where  it  divides  into  two  unequal  parts,  an  upper  and  smaller,  and  a 
lower  more  capacious  ;  sometimes  it  corresponds  entirely  to  the  upper  part  of  the  sac. 
At  first  it  is  flattened  from  before  backward,  but  is  then  twisted  upon  itself,  so  as  to  pre- 
sent one  surface  upward  and  another  downward.  Opposite  the  inner  angle  of  the  eye- 
lids, this  tendon,  which  is  also  called  the  palpebral  ligament,  becomes  bifurcated,  and 
each  division  is  attached  to  the  inner  end  of  the  corresponding  tarsal  cartilage  ;  from  the 
posterior  surface  of  the  tendon  a  very  strong  aponeurotic  lamina  is  given  off,  and  forms 
the  outer  wall  of  the  lachrymal  sac  :  this  is  the  reflected  tendon  of  the  orbicularis  palpebra- 
rum. Fleshy  fibres  proceed  from  the  anterior  and  posterior  surfaces,  and  from  the  bor- 
ders of  the  straight  tendon,  and  also  from  the  anterior  border  of  the  reflected  tendon  ; 
but  the  greater  number  arise  by  well-marked  tendinous  prolongations  from  the  external 
orbital  process  of  the  frontal  bone,  from  the  ascending  process  of  the  superior  maxilla, 
and  from  the  internal  and  lower  third  of  the  base  of  the  orbit.  From  these  origins  the 
fleshy  fibres  pass  outward,  dividing  into  two  halves,  an  upper,  which  describes  concen- 
tric curves  with  the  concavity  directed  downward,  and  a  lower,  also  describing  concen- 
tric curves,  but  with  the  concavity  directed  upward  (duo  palpebrarum  musculi,  Vcsalius). 
Each  of  these  halves  is  subdivided  into  two  sets  of  fibres  :  an  external  set,  surrounding 
the  base  of  the  orbit ;  and  an  internal  or  palpebral,  belonging  to  each  eyelid  :  hence  the 
distinction  drawn  by  Riolanus  between  the  orbicularis  and  the  ciliaris  or  palpebralis  mus- 
cles. The  external  fibres  (forming  the  orbicular  portion)  describe  a  complete  ellipse.  I 
have  never  met  with  the  fibrous  intersection  at  the  outer  part  of  the  eye,  mentioned  by 
some  anatomists.  The  palpebral  or  ciliary  fibres,  forming  the  proper  palpebral  portion, 
arise  from  the  bifurcation  of  the  tendon,  and  describe  concentric  arcs,  which  are  united 
on  the  outside  at  an  acute  angle  to  a  cellular  raphe. 

Relations. — The  orbicular  portion  is  closely  united  to  the  skin  by  means  of  a  fibrous 
and  adipose  tissue,  which  is  very  compact  over  the  upper,  and  loose  over  the  lower  por- 
tion of  the  muscle  ;  it  is  connected  with  the  skin  of  the  eyelids  by  a  serous  cellular  tis- 
sue, remarkably  susceptible  of  infiltration.  It  covers  the  lachrymal  sac,  the  corrugator 
supercilii  muscle,  the  orbited  arch,  the  maxillary  bone,  the  temporal  muscle,  and  the  su- 
perior attachments  of  the  zygomaticus  major,  of  the  levator  labii  superioris  alaeque  nasi, 
and  of  the  levator  labii  superioris. 

It  is  separated  from  the  conjunctiva  by  a  fibrous  membrane  and  the  tarsal  cartilages. 
Its  circumference  is  blended  with  the  pyramidalis  nasi  on  the  inside,  with  the  occipito- 
frontalis  and  corrugator  above,  but  is  free  below ;  occasionally  it  gives  off  a  few  fibres 
from  its  outer  border,  some  of  which  form  the  zygomaticus  minor,  and  others  of  a  pailer 
colour  terminate  in  the  skin. 

Actions. — ^The  orbicularis  acts  in  the  same  manner  as  £ill  other  sphincters,  that  is  to 
say,  the  circular  fibres  of  which  it  is  composed  contract  towards  the  centre  ;  but,  as  the 
fleshy  fibres  have  their  fixed  point  at  the  straight  tendon,  and  still  more  at  the  internal 
insertions,  it  follows  that,  during  the  contraction  of  this  muscle,  it  is  thrown  in  some 
measure  inward,  and  by  it  the  integuments  of  the  forehead,  the  temple,  and  the  cheek 
are  drawn  towards  the  inner  angle  of  the  eye.  The  intimate  adhesion  between  the  skin 
and  the  upper  half  of  the  muscle  explains  why,  during  its  contraction,  that  part  is  ren- 
dered more  apparent  beneath  the  skin  than  the  lower.  The  palpebral  portion  contracts 
independently  of  the  orbicular,  a  fact  that  confirms  the  distinction  made  by  Riolanus. 
Nor  is  this  all :  the  contraction  of  this  palpebral  portion,  or  palpebralis  muscle,  properly  so 
called,  is  habitually  involuntary,  while  the  contraction  of  the  orbicular  portion  is  subject 
to  the  will.  The  palpebral  fibres  are  pale,  and  resemble  the  muscular  fibres  of  the  ali- 
mentary organs  ;*  the  orbicular  fibres  are  red,  like  those  of  the  muscles  of  animal  life. 
When  the  palpebral  fibres  contract,  they  do  not  produce  the  occlusion  of  the  eye,  by  a 
concentric  approximation  of  the  fibres,  but  by  bringing  together  the  free  edges  of  the  eye- 
lids, the  only  method  permitted  by  the  tarsal  cartilages.  The  curve  described  by  the 
rnuscular  fibres  of  the  lower  being  smaller  than  that  formed  by  those  of  the  upper  eye- 
lid, it  follows  that  the  closing  of  the  eyes  depends  principally  upon  the  latter. 

The  Super  ciliaris. 

Dissection. — Make  a  vertical  incision  in  the  median  line  between  the  frontal  muscles  ; 
ttim  back  carefully  the  frontal  and  the  orbicularis  muscles  from  within  outward. 

The  superciliaris  (corrugator  supercilii,  Albinus,  a',  Jig.  114)  is  a  narrow  and  tolerably 
thick  fasciculus,  generally  of  a  deeper  red  than  the  orbicularis,  and  situated  along  the 
superciliary  arch,  with  the  direction  of  which  it  corresponds.  It  arises  by  one,  often  by 
two  or  three  portions,  from  the  internal  portion  of  this  arch ;  proceeds  upward  and  out- 
ward, describing  a  slight  curve,  having  its  concavity  downward,  and  is  blended  with  the 
orbicularis  palpebrarum  at  about  the  middle  of  the  arch  of  the  orbit.  From  this  arrange- 
ment, Albinus  described  it  as  a  root  of  the  orbicularis.  According  to  some  authors,  it 
terminates  in  the  skin  of  the  eyebrow  (cutaneo-surcilier,  Dumas) ;  but  I  have  always 
found  it  attached  to  the  deep  layer  of  the  orbicularis  muscle. 

*  See  note  *,  p.  238. 


THE    LEVATOR    PALPEBE^    SUPERIORIS,    ETC.  2SSt 

Relations. — It  is  covered  by  the  pjrramidalis  nasi,  the  orbicularis  palpebrarum,  and  the 
occipito-frontalis,  and  it  covers  the  os  frontis,  the  supra-orbital  and  frontal  arteries,  and 
the  frontal  branch  of  tlie  ophthalmic  nerve. 

Action. — This  muscle  corrugates  the  eyebrow,  and  dravrs  it  downward  and  inward.  It 
is,  therefore,  regarded  as  the  principal  agent  in  the  expression  of  grief  The  repeated 
contraction  of  these  muscles  in  irascible  individuals  gives  a  character  of  severity  to  the 
countenance,  from  the  constant  approximation  of  the  eyebrows,  and  the  permanence  of 
the  vertical  wrinkles  formed  between  them. 

The  Levator  Palpebrce  Supreioris. 

Dissection. — Remove  the  roof  of  the  orbit  by  two  cuts  with  a  saw,  meeting  at  an  acute 
angle  opposite  the  foramen  opticum  ;  detach  the  bone  with  care,  so  as  to  leave  the  peri- 
osteum untouched ;  cut  the  periosteum  from  before  backward,  and  separate  the  frontal 
nerve  which  passes  above  and  parallel  to  the  muscle,  which  may  then  be  separated  care- 
fully from  the  superior  rectus  muscle  of  the  eye. 

The  levator  palpebro'.  superioris  (see  description  of  the  eyelids)  is  an  elongated,  flat, 
triangular,  and  very  thin  muscle,  placed  in  the  orbital  cavity,  directed  horizontally  from 
behind  forward,  and  curved  at  its  anterior  extremity,  sa  as  to  form  a  concavity  directed 
downward.  It  arises  from  the  inferior  surface  of  the  lesser  wing  of  the  sphenoid,  im- 
mediately above  the  optic  foramen,  and  from  the  sheath  of  the  optic  nerve,  and  is  insert- 
ed into  the  upper  border  of  the  tarsal  cartilage.  Its  sphenoidal  origin  consists  of  a  small 
tendon,  and  its  attachment  to  the  sheath  of  the  optic  nerve  is  a  fibrous  ring  common  to 
aU  the  muscles  of  the  eye.  From  these  points  the  fleshy  fibres  proceed  forward,  form- 
ing a  broad,  thin  bundle,  increasing  in  width  and  diminishing  in  thickness  towards  its 
tarsal  insertion,  which  is  effected  by  means  of  a  broad  aponeurosis. 

Relations. — Covered  by  the  periosteum  of  the  orbit,  from  which  it  is  separated  by  the 
frontal  branch  of  the  ophthalmic  nerve ;  covered,  also,  by  some  adipose  tissue  and  by  the 
fibrous  membrane  of  the  upper  eyelid,  it  covers  the  superior  rectus  of  the  eye  and  the 
conjunctiva. 

Action. — It  raises  the  upper  eyelid.  Its  reflection  over  the  globe  of  the  eye  explains 
that  peculiar  motion  of  the  eyelid  by  which  its  upper  edge  is  buried  below  the  orbital 
arch.  The  relaxation  of  this  muscle  suffices  for  the  depression  of  the  upper  eyelid  in 
passive  closure  of  the  eyes,  while  the  active  occlusion  depends  on  the  contraction  of  the 
orbicularis. 

There  is  no  analogous  muscle  for  the  lower  eyelid,  which  scarcely  concurs  either  in 
opening  or  shutting  the  eyes. 


NASAL  REGION. 

The  Pyramidalis  Nasi. — Levator  Labii  Superioris  Alceque  Nasi. — Tranaver salts,  or  Trian- 
gularis Nasi. — Depressor  Ala.  Nasi. — Naso-labialis. 
The  muscles  of  this  region  are  the  pyramidalis  nasi,  the  levator  labii  superioris  alae- 
que  nasi,  the  transversalis  or  triangularis  nasi,  the  depressor  alae  nasi,  or  myrtiformis, 
and  the  naso-labialis  of  Albinus. 

The  Pyramidalis  Jfasi. 

Dissection. — ^Trace  doiwn  upon  the  dorsum  of  the  nose  the  internal  fibres  of  the  occip- 
ito-frontalis, directing  the  scalpel  parallel  to  these  fibres,  which  have  a  vertical  course. 

The  pyramidalis  nasi  (/,  fig.  113)  is  a  prolongation  of  the  internal  fibres  of  the  occipito- 
frontalis,  of  which  it  may  be  regarded  as  a  prolongation  (frontahs  pars  per  dorsum  nasi 
ducta,  Eustachius).  It  lies  upon  the  bridge  of  the  nose  on  each  side  of  the  median  line. 
It  is  separated  from  the  muscle  of  the  opposite  side  by  a  thin  layer  of  cellular  tissue.  It 
is  narrower  at  its  origin  than  at  its  termination,  which  takes  place  in  the  aponeurosis  of 
the  transverse  muscle  of  the  nose. 

Relations. — It  is  covered  by  the  skin,  to  which  it  closely  adheres,  especially  below,  and 
it  covers  the  nasal  bones  and  lateral  cartilages. 

Action. — This  small  muscle  has  been  regarded  as  an  elevator  of  the  ala.  and,  conse- 
quently, a  dilator  of  the  nose  ;  but  I  believe  it  rather  acts  in  depressing  the  inner  angle 
of  the  eyebrow,  and  the  skin  between  the  eyebrows.  In  this  respect  it  has  considerable 
influence  upon  the  expression  of  the  countenance. 

The  Levator  Labii  Superioris  AlcRque  JSTasi. 
Dissection. — Make  a  vertical  or  somewhat  oblique  incision  from  the  ascending  process 
of  the  superior  maxilla  to  the  upper  lip.    Reflect  outward  the  inner  and  lower  part  of  the 
orbicularis  muscle. 

This  muscle  (^,  fig.  113)  is  thin,  triangular,  and  divided  into  two  portions  below.  It 
extends  from  the  ascending  process  of  the  superior  maxilla  to  the  ala  of  the  nose  and  the 
^upper  lip.  It  arises  by  a  narrow  extremity  from  the  internal  orbital  process  of  the  frontal 
bone,  immediately  below  the  tendon  of  the  orbicularis  palpebrarum,  passes  obliquely 

Go 


234  T    ,?   >7,  MYOLOGY. 

downward  and  outward,  becomes  much  broader,  and  is  inserted  partly  into  the  cartilage 
of  the  ala  of  the  nose,  or,  rather,  into  the  very  dense  skin  which  covers  it,  and  partly  into 
the  orbicularis  oris,  or,  rather,  into  the  skin  of  the  upper  lip.  The  cutaneous  portion  of 
this  muscle  is  distinguished  by  its  paleness,  compared  with  the  red  colour  of  the  rest. 

Relations. — It  is  covered  by  the  skin,  and  a  small  portion  of  the  orbicularis  palpebrarum ; 
and  it  covers  the  ascending  process  of  the  superior  maxilla,  and  the  transverse  muscle  of 
the  nose. 

Action. — It  elevates  both  the  ala  of  the  nose  and  the  upper  lip.  I  consider  it  the  most 
important  of  all  the  muscles  of  the  nose,  because  the  elevation  of  the  alae  dilates  the  nos- 
trils, and  thus  aids  most  essentially  in  cases  of  impeded  respiration.  It  is  a  respiratory 
muscle  of  the  face,  and  has,  also,  great  influence  over  the  countenance,  producing  the 
expression  of  contempt.  Its  action  upon  the  upper  lip  is  of  much  less  importance  than 
that  upon  the  nose. 

The  Transversalis,  or  Triangularis  JVasi. 

Dissection. — Remove  with  great  care  the  skin  covering  the  ala  of  the  nose,  and  then  fol- 
low this  muscle  below  the  inner  edge  of  the  common  elevator ;  or,  what  is  better,  remove 
all  the  soft  parts  covering  the  ala  of  the  nose,  and  dissect  the  muscle  from  its  deep  surface. 

The  transversalis  vusi  (compressor  narium,  h',figs.  113,  114),  which  I  regard  as  a  de- 
pendance  of  the  muscle  next  to  be  described,  is  a  small  and  very  thin  triangular  muscle, 
stretching  from  the  inner  part  of  the  canine  fossa  to  the  bridge  of  the  nose.  It  arises  by 
a  narrow  extremity  from  the  canine  fossa,  passes  forward,  enlarging  as  it  proceeds  along 
the  ala  of  the  nose,  and  terminates  by  a  very  thin  aponeurosis,  which  is  blended  in  the 
median  line  with  that  of  the  opposite  side,  and  with  the  pyramidalis.  It  is  covered  by 
the  skin,  to  which  it  closely  adheres,  and  by  the  common  elevator ;  and  it  covers  the  car- 
tilage of  the  ala,  and  a  small  part  of  the  superior  lateral  cartilage  of  the  nose. 

Action. — The  action  of  this  small  muscle  is  not  yet  weU  determined.  Some  have 
agreed  with  Riolanus  in  considering  it  a  dilator  (qui  alam  naris  diktat  sine  elevatione 
nasi,  Riolanus) ;  others  think,  with  Spigelius  and  Albinus,  that  it  is  a  constrictor  of  the 
nose  (primi  paris  constringentium  alas,  Spigelius ;  compressor  naris,  Albinus).  It  is  prob- 
able that  its  action  varies  according  to  the  shape  of  the  ala :  if  this  be  concave  outward, 
it  is  a  dilator ;  if  convex  outward,  it  is  a  constrictor.     Its  action  is  very  slight. 

The  Depressor  Alee  JVasi,  or  Myrtiformis. 

Dissection. — Evert  the  upper  lip,  and  remove  the  mucous  membrane  on  each  side  of 
the  fraenum.  The  two  myrtiformes  may  then  be  separated  by  a  vertical  incision  in  the 
median  line.  It  will  be  apparent  that  the  myrtiformis  and  transversalis  form  only  one 
muscle,  which  arises  from  the  alveolar  border  near  the  lateral  incisor,  the  canine  and  the 
anterior  bicuspid  teeth,  and  is  distributed  to  the  orbicularis  oris,  the  alae,  and  the  septum 
of  the  nose. 

This  muscle  {if,  fig-  114)  is  short  and  radiated,  and  arises  by  a  narrow  extremity  from 
the  incisive  or  myrtiform  fossa  of  the  superior  maxilla,  opposite  the  canine  and  two  in- 
cisor teeth  (incisif  moyen,  Winslow).  Its  fibres  diverge  upward  and  outward,  and  are  in- 
serted thus  :  the  lower,  or  descending,  behind  and  in  the  substance  of  the  orbicularis  oris  ; 
and  the  upper  or  ascending,  into  the  ala  and  septum  of  the  nose.  Its  upper  border  is 
not  distinct  from  the  lower  border  of  the  transversalis.  Chaussier,  on  account  of  its 
termination  in  the  upper  lip,  regarded  it  as  one  of  the  origins  of  the  orbicularis  oris. 

Relations. — It  is  covered  by  the  buccal  mucous  membrane,  by  the  orbicularis  oris,  and 
the  common  elevator,  and  it  lies  upon  the  maxillary  bone.  It  is  continuous,  without  any 
line  of  demarcation  with  the  transversalis  nasi.  The  inner  border  of  the  muscle  of  one 
side  is  separated  from  that  of  the  other  by  an  interval,  corresponding  to  the  fraenum  of 
the  upper  lip. 

Action. — It  depresses  the  ala  of  the  nose,  and  has  also  been  considered  a  depressor  of 
the  upper  lip  (depressor  labii  superioris,*  Cowper).  I  regard  it  rather  as  an  elevator  of 
that  lip. 

The  J^aso-labialis  of  Albinus. 
This  consists  of  a  fasciculus  which  it  is  difficult  to  demonstrate  in  many  subjects.    It 
arises  from  the  anterior  extremity  of  the  septum  of  the  nose,  passes  horizontally  back 
ward,  is  then  reflected  downward,  and  terminates  like  the  preceding  in  the  orbicularis, 
of  which  it  may  be  considered  a  root. 


MUSCLES  OF  THE  LABIAL  REGION. 
rhe  Orbicularis  Oris. — Buccinator. —  Levator  Labii  Superioris. — Caninus. —  Zygomatict, 
Major  et  Minor. — Triangularis. — Quadratus  Menti. — Levator  Labii  Superioris. — Move- 
ments  of  the  Lips  and  those  of  the  Face. 

No  region  has  so  many  muscles  as  the  orifice  of  the  mouth  :  seventeen,  nineteen,  and 
*  Depressor  labii  superioris  aliBque  nasi  of  other  writers. 


THE    ORBICULARIS    ORIS   AND    THE    BUCCINATOR.  4)85 

often  twenty-one  muscles,  are  grouped  round  it,  viz.,  the  orbicularis  oris,  the  common 
elevators  of  the  alae  and  lip  already  described,  the  proper  elevators  of  the  lip,  the  great  zy- 
gomatics, the  canine,  the  buccinators,  the  triangulares,the  quadrati  or  the  levatores  menti ; 
and  often  two  muscles  on  each  side,  viz.,  the  risorius  of  Santorini,  and  the  small  zygomatic. 

The  Orbicularis  Oris. 

Dissection. — Make  an  elliptical  incision  round  the  opening  of  the  mouth,  and  dissect 
back  the  skin  with  great  care,  the  mouth  being  previously  distended  by  the  introduction 
of  tow  between  the  lips  and  alveolar  borders. 

The  orbicularis  oris  (J,'  I',  figs.  113  and  114)  is  the  sphincter  of  the  orifice  of  the  mouth  ; 
it  is  essentially  the  constituent  muscle  of  the  lips,  occupying  the  entire  space  betweeii 
the  free  edge  of  the  upper  lip  and  the  nose,  and  the  free  edge  of  the  lower  lip  and  the 
transverse  furrow  above  the  chin. 

We  shall  consider,  with  Winslow,  the  orbicularis  to  be  composed  of  two  halves,  each 
constituted  by  a  demi-zone,  of  semi-elliptical  concentric  fibres,  terminating  on  either  side 
at  the  commissures  of  the  lips.  These  fibres,  which  are  all  fleshy,  do  not  become  con- 
tinuous opposite  the  commissures  of  the  lips,  but  only  intersect  each  other,  those  of  the 
upper  half  being  continuous  with  the  lower  fibres  of  the  buccinator,  and  those  of  the  low- 
er half  with  the  upper  fibres  of  the  same  muscle. 

The  thickness  of  the  two  halves  varies  in  different  individuals,  particularly  around  the 
free  borders  of  the  lips,  where  the  fasciculi  of  the  muscle  are  somewhat  everted.  In 
the  negro  this  is  very  remarkable.  The  thickness  of  the  lips  depending  upon  this  cir- 
cumstance must  be  distinguished  from  that  which  is  the  effect  of  a  scrofulous  habit. 

Relations. — These  muscles  are  covered  by  the  skin,  to  which  they  adhere  intimately, 
and  hence  the  facility  of  bringing  together  the  entire  depth  of  the  surface  of  wounds  in 
the  lips,  by  retentive  applications  to  the  skin  only.  They  cover  the  mucous  membrane 
but  are  separated  from  it  by  the  labial  glands,  the  coronary  vessels,  and  a  great  number 
of  nervous  filaments.  Their  outer  circumference  receives  all  the  extrinsic  muscles  of 
the  lips,  which  terminate  in  these  as  in  a  conmion  centre.  Their  inner  circumference 
circumscribes  the  opening  of  the  mouth.  The  differences  in  the  dimensions  of  this  open- 
ing occasion  the  varieties  observed  in  the  size  of  the  mouth,  but  the  capacity  of  the  buc- 
cal cavity  is  in  no  way  influenced  by  these  variations. 

Actions. — These  are  exceedingly  various,  and  may  be  studied  as  connected  with  the 
closing  of  the  mouth,  with  the  prehension  of  aliments  by  suction,  with  the  playing  upon 
wind  instruments,  and  with  the  expression  of  the  countenance.  I  shall  here  only  notice 
the  shutting  of  the  mouth. 

This  may  be  accomplished  simply  by  the  approximation  of  the  jaws,  which  is  followed 
by  a  corresponding  motion  of  the  lips.  In  active  occlusion,  or  that  dependant  on  the 
orbicularis,  two  things  may  happen  :  either  the  lips  may  be  closely  drawn  against  the 
teeth,  and  their  free  edges  applied  to  each  other,  or  they  may  be  pushed  forward  and 
puckered ;  in  the  latter  case,  the  buccal  opening,  which  is  usually  represented  by  a  trans- 
verse line,  resembles  a  circular,  or,  rather,  a  lozenge-shaped  orifice. 

The  Buccinator. 

Dissection. — Distend  the  cheeks  by  stuffing  the  mouth  with  tow ;  make  a  transverse 
incision  through  the  skin,  from  the  commissure  of  the  lips  to  the  masseter  muscle,  and 
dissect  back  the  flaps':  in  order  to  gain  a  good  view  of  the  posterior  border  of  the  mus- 
cle, turn  downward  the  zygomatic  arch  and  the  masseter,  and  then  divide  with  the  saw 
the  inferior  maxilla  in  front  of  the  ramus. 

The  buccinator  (fig.  113,  and  b,figs.  114  and  147)  is  the  proper  muscle  of  the  cheek; 
it  is  broad,  thin,  and  irregularly  quadrilateral.  It  is  attached  above  to  the  external  sur- 
face of  the  superior  alveolar  arch,  along  the  space  between  the  first  great  molar  and  the 
tuberosity  of  the  maxilla  ;  below,  to  the  external  surface  of  the  inferior  alveolar  arch, 
or,  rather,  to  that  part  of  the  external  oblique  line  of  the  lower  jaw  which  corresponds 
with  the  last  two  great  molars  ;  and  behind,  to  an  aponeurosis  existing  between  this 
muscle  and  the  superior  constrictor  of  the  pharynx  (see  fig.  147).  This  aponeurosis,  to 
which  the  name  of  buccinato-pharyngeal  has  been  given  {ptery go-maxillary  ligament),  ex- 
tends from  the  apex  of  the  internal  pterygoid  process  to  the  posterior  extremity  of  the 
internal  oblique  line  of  the  lower  jaw.  From  these  different  origins  the  fleshy  fibres 
proceed  forward,  the  upper  somewhat  obliquely  downward,  the  lower  obliquely  upward, 
and  the  middle  fibres  horizontally.  In  consequence  of  this  arrangement,  the  fibres  inter- 
sect each  other  opposite  the  commissure  of  the  lips,  from  which  points  the  lower  fibres 
of  the  muscle  proceed  to  terminate  in  the  upper  half  of  the  orbicularis,  while  the  upper 
fibres  end  in  the  lower  half  of  the  same  muscle. 

Relations. — It  is  situated  deeply  behind,  where  it  is  covered  by  the  ramus  of  the  lower 
jaw,  the  masseter,  and  a  small  part  of  the  temporal  muscle  ;  from  all  these  parts,  how- 
ever, it  is  separated  by  a  considerable  quantity  of  adipose  tissue,  and  by  a  mass  of  fat 

which  exists  even  in  the  most  emaciated  individuals.    More  anteriorly  it  is  covered  by 

■-■■'•.■"■~,Trrr"''"    " 


236  MYOLOGY. 

the  zygomaticus  major  and  the  zygomaticus  minor,  and  the  risonus  jf  Santorini,  where 
the  two  latter  exist ;  and  at  the  commissure  it  is  covered  by  the  canine  muscle  {levator 
angnli  oris)  and  the  triangularis.  The  Stenonian  duct  runs  along  this  muscle  before 
passing  through  it ;  the  buccal  nerves  and  the  branches  of  the  transverse  facial  artery 
lie  parallel  to  its  fibres;  the  external  maxillary  (i.  e.,  the  facial)  artery  and  vein  pass 
perpenaicularly  across  it,  near  the  commissure.  A  peculiar  aponeurosis,  called  the  buc- 
cal fascia,  is  closely  united  to  it,  and  intervenes  between  it  and  all  these  parts.  It  cov- 
ers the  mucous  membrane  of  the  cheek,  from  which  it  is  separated  by  a  dense  layer  of 
the  buccal  mucous  glands. 

Action. — It  is  the  most  direct  antagonist  of  the  orbicularis.  When  the  cheeks  are  not 
distended,  its  contraction  elongates  the  opening  of  the  mouth  transversely,  and,  conse- 
quently, renders  the  hps  tense,  and  produces  a  vertical  fold  upon  the  skin  of  the  cheek. 
This  fold  becomes  permanent  in  the  aged,  and  constitutes  one  of  their  most  prominent 
wrinkles. 

When  the  cheeks  are  distended  by  air,  or  any  other  substance,  the  buccinator  becomes 
curved  instead  of  flat,  and  acquires  all  the  properties  of  the  former  class  of  nmscles. 
Thus  the  first  effect  of  its  contraction  is,  that  its  fibres  become  straight,  or  have  a  ten- 
dency to  become  so ;  gaseous,  liquid,  or  solid  bodies,  are  then  expelled  from  the  mouth, 
rapidly  if  the  orbicularis  offer  no  obstacle,  and  gradually  should  that  muscle  contract. 
The  buccinator,  therefore,  fulfils  an  important  ofiice  in  performances  upon  wind  instru- 
ments, and  hence  its  name  {buccinare,  to  sound  the  trumpet).  la  mastication  it  is  of  no 
less  importance,  since  it  pushes  the  food  between  the  teeth,  and  expels  it  from  the  sort 
of  groove  existing  between  the  cheeks  and  the  alveolar  arches. 

The  Levator  Labii  Superioris. 

Dissection. — Reflect  the  lower  half  of  the  orbicularis  palpebrarum  upward,  and  dissect 
with  care  the  lower  extremity  of  the  muscle  about  to  be  described,  which  adheres  close- 
ly to  the  skin.     It  can  be  best  studied  from  the  inner  surface. 

This  muscle  (c',  fig.  1 14)  is  thin  and  quadrilateral.  It  is  situated  upon  the  same  plane 
as  the  common  elevator,  of  which  it  appears  to  be  a  continuation,  and  extends  from  the 
base  of  the  orbit  to  the  skin  of  the  upper  lip. 

It  arises  from  the  inner  half  of  the  lower  edge  of  the  base  of  the  orbit,  on  the  outei 
side  of  the  common  elevator  :  from  this  origin,  which  is  sometimes  bifid,  the  fibres  con- 
verge dovraward  and  inward,  and  are  inserted  successively  into  the  skin,  probably  into 
the  bulbs  of  the  hairs,  as  in  animals  which  have  mustaches  ;  so  that  this  muscle  would 
deserve  the  name  of  mustachie,  which  is  given  by  some  anatomists  to  the  naso-labial  of 
Albinus. 

Relations. — Its  two  upper  thirds  are  deeply  seated ;  its  lower  third  adheres  closely  to 
the  skin.  It  is  worthy  of  notice,  that  almost  all  the  muscles  of  the  face  are  deeply 
seated  at  one  of  their  extremities,  and  terminate  by  the  other  in  the  skin.  It  is  covered 
by  the  orbicularis  palpebrarum  and  the  skin,  and  it  covers  the  infra-orbital  vessels  and 
nerves,  as  they  escape  from  the  infra-orbital  canal.  It  is  also  in  relation  with  the  ca- 
nine muscle,  from  which  it  is  separated  by  a  quantity  of  adipose  tissue,  with  the  trans- 
versalis  nasi,  and  with  the  orbicularis  oris,  being  interposed  between  the  latter  muscle 
and  the  skin. 

Action. — It  raises  the  upper  lip,  and  draws  it  a  little  outward. 

The  Caninus. 

Dissection. — Merely  reflect  the  levator  labii  superioris. 

The  canine  muscle  (levator  anguli  oris,  Albinus,  d,fig.  114),  so  named  from  its  origin, 
arises  from  the  canine  fossa  by  a  broad  attachment,  from  which  it  proceeds  downward 
and  a  little  outward,  diminishing  in  size,  and  becoming  gradually  more  superficial,  to 
the  commissure  of  the  lips,  where  it  terminates  by  uniting  with  the  zygomaticus  major, 
and  becoming  continuous  with  the  triangularis  oris.  We  often  find  some  accessory 
fibres  arising  from  this  muscle,  and  attached  to  the  skin  opposite  the  commissure. 

Relations. — Above,  it  is  concealed  by  the  levator  labii  superioris  and  the  infra-orbitary 
vessels  and  nerves  ;  below,  it  is  quite  superficial,  being  only  covered  by  the  skin.  It 
covers  the  superior  maxilla,  the  buccinator,  and  the  buccal  mucous  membrane. 

Action. — It  raises  the  angle  of  the  mouth,  and,  from  its  oblique  position,  draws  it  inward. 

The  Zygomatici  Major  et  Minor. 

Dissection. — Make  an  oblique  incision  from  the  malar  bone  to  the  commissure  of  the 
lip,  and  remove  carefully,  from  the  great  zygomatic,  the  fatty  tissue  which  surrounds  it. 

The  Zygomaticus  Major. 

This  muscle  {m',fig.  113)  is  a  cylindrical,  fleshy  fasciculus,  extending  from  the  malar 

bone  to  the  conunissure  of  the  hp.     It  arises,  by  tendinous  fibres,  from  the  entire  length 

of  a  horizontal  furrow,  situated  above  the  lower  edge  of  the  malar  bone.     The  fleshy 

fibres  approach  each  other  so  as  to  form  a  fasciculus,  which  passes  obliquely  downward 


THE    TRIANGULARIS,    ETC.  237 

and  inward  towards  the  commissure,  where  it  is  closely  united  to  the  canine  muscle, 
and,  like  it,  is  continuous  with  the  triangularis  or  depressor  anguli  oris. 

Relations. — It  is  covered  by  the  skin,  from  which  it  is  separated  above  by  the  orbicu- 
laris palpebrarum,  and  below  by  a  large  quantity  of  adipose  tissue  ;  it  covers  the  malar 
bone,  the  masseter  and  buccinator  muscles,  a  great  collection  of  fat,  and  the  labial  vein. 

Action. — It  draws  the  angle  of  the  mouth  upward  and  outward  ;  by  carrying  the  com- 
missure upward,  it  assists  the  canine  muscle,  but  in  drawing  it  outward,  it  antagonizes  the 
same.  When  the  zygomatic  and  canine  contract  together,  the  commissure  is  drawn  di- 
rectly upward. 

The  Zygomaticus  Minor.    • 

This  small  muscle  {n',fig.  113),  which  is  often  wanting,  maybe  regarded  as  a  depend- 
ance  of  the  proper  elevator  of  the  upper  lip.  It  arises  from  the  malar  bone,  above  the 
great  zygomatic,  passes  downward  and  inward  to  the  outer  border  of  the  levator  labii  su- 
perioris,  with  which  it  is  blended.  It  is  not  uncommon  to  find  this  muscle  enlarged  by 
fasciculi  given  off  from  the  outer  and  lower  circumference  of  the  orbicularis  muscle  of 
the  eyelids.  It  is  covered  by  the  skin  and  the  orbicularis  palpebrarum ;  and  it  covers 
the  canine  muscle  and  the  labial  vein. 

Action. — It  assists  the  common  elevator  in  raising  the  upper  lip  and  drawing  it  some- 
what outward. 

The  Triangularis,  or  Depressor  Anguli  Oris. 

Dissection. — Make  a  vertical  incision  of  the  skin,  from  the  commissure  of  the  lips  to  the 
base  of  the  jaw  ;  then  follow  the  course  of  the  muscidar  fibres  as  they  are  successively 
exposed. 

This  muscle  {o',fig.  113)  is  of  a  triangular  shape,  as  its  name  implies,  and  belongs  to 
the  inferior  maxillary  region.  It  arises,  by  a  broad  base  within,  from  the  lower  border  of 
the  inferior  maxilla  on  the  side  of  the  median  line,  and  sometimes  from  the  median  line 
itself;  and  without,  from  the  external  oblique  line  :  from  these  points  the  fibres  pass  in 
different  directions,  the  external  almost  vertically  upward,  the  internal  obliquely  upward 
and  outward  (the  obliquity  increasing  as  we  proceed  inward),  and  describing  a  curve  with 
the  concavity  looking  inward.  All  these  fibres  are  concentrated  into  a  narrow  and  thick 
fasciculus,  which  terminates  at  the  commissure,  on  a  plane  anterior  to  the  fibres  of  the 
buccinator  and  the  orbicular  oris,  being  evidently  continuous  with  the  canine  and  the 
great  zygomatic. 

Relations. — It  is  covered  by  the  skin,  beneath  which  it  is  clearly  discernible,  and  it  cov- 
ers the  quadratus  menti,  the  platysma,  and  the  buccinator.  Some  colourless  fibres,  which 
intersect  those  of  the  quadratus  at  a  right  angle,  and,  moreover,  follow  the  same  direc- 
tion as  those  of  the  triangularis,  may  be  regarded  as  a  dependance  of  that  muscle,  to  the 
inside  of  which  they  are  situated.     They  terminate  in  the  skin,  like  those  of  the  quadratus. 

Action. — It  depresses  the  angle  of  the  mouth,  thus  antagonizing  the  canine  muscle  and 
the  great  zygomatic,  with  which  it  is  continuous.  The  continuity  of  these  muscles  is  so 
manifest,  that  they  may  be  regarded  as  constituting  a  single  muscle,  broad  and  triangu- 
lar below ;  bifid  above,  to  form  the  canine  and  zygomatic ;  and  narrow  in  the  middle, 
where  it  corresponds  to  the  commissure.  The  internal  fibres  of  the  triangularis,  from 
their  oblique  direction,  are  directly  opposed  to  those  of  the  canine  muscle  ;  but  its  exter- 
nal fibres  have  not  a  similar  relation  to  those  of  the  zygomaticus  major. 

The  Quadratus  Menti,  or  Depressor  Labii  Inferioris. 

Dissection. — Dissect  back  the  skin  covering  this  muscle,  cutting  obliquely  downward 
and  outward. 

The  quadratus  menti  {-p'tfig.  113 ;  q',fig.  114),  situated  to  the  inside  of  the  preceding,  is 
of  a  square,  or,  rather,  lozenge  shape.  It  arises  from  the  external  oblique  line  of  the  low- 
er jaw,  and  is  in  a  great  measure  continuous  with  the  platysma,  the  fibres  of  wliich  pass 
behind,  and  sometimes  through  the  triangularis.  From  this  origin  it  proceeds  obliquely 
upward  and  inward,  therefore  in  an  opposite  direction  to  the  triangularis,  and  is  inserted 
into  the  skin  of  the  lower  lip,  on  a  plane  anterior  to  the  corresponding  half  of  the  orbicu- 
laris oris.  It  is  closely  united  to  the  skin,  and  covers  the  lower  jaw,  the  mental  nerve 
and  vessels,  the  lower  half  of  the  orbicularis  oris,  and  the  muscle  next  to  be  described, 
with  which  it  is  intimately  connected.  It  is  separated  from  the  muscle  of  the  opposite 
side  by  the  prominence  of  the  chin  below,  but  is  blended  with  it  above. 

Action. — It  depresses  the  lower  lip  :  from  the  obliquity  of  this  muscle,  it  also  draws  out- 
ward and  downward  each  half  of  the  lower  lip,  which  is  therefore  stretched  transversely. 

The  Levator  Labii  Inferioris. 
Dissection. — Evert  the  lower  lip  ;  divide  the  mucous  membrane  at  its  reflection  upon 
the  lip  from  the  lower  jaw,  so  as  to  expose  the  origin  of  the  muscle.  In  order  to  show 
its  cutaneous  insertion,  carefully  dissect  off  the  skin  covering  the  chin.  As  the  muscles 
of  each  side  are  blended  in  the  median  line,  it  is  necessary  to  make  a  vertical  incision 
from  before  backward,  opposite  the  symphysis,  in  order  to  separate  them. 


2^  MYOLOGY. 

This  muscle  (levator  menti,  Alb.,  r',Jig.  114)  is  a  small  conoid  fasciculus,  which  forma, 
in  a  great  measure,  the  prominence  of  the  chin.  It  arises  from  the  facette  on  the  side  of 
the  symphysis  menti,  opposite  the  incisor  teeth,  whence  the  name  incisif  inferieur,  Wins- 
low,  which  is  also  given  to  this  muscle.  From  this  point  the  fibres  expand  like  a  tuft, 
downward  and  forward,  to  be  inserted  into  the  skin.  It  is  red  and  fasciculated  at  its  or- 
igin above,  but  pale,  intermixed  with  fat,  and  not  fasciculated  below,  where  it  is  blended 
on  the  inside  with  the  opposite  muscle,  and  on  the  outside  with  the  quadratus  menti. 
Its  upper  fibres  form  a  concavity  above,  which  partially  embraces  the  great  circumfer- 
ence of  the  lower  half  of  the  orbicularis  oris. 

Action. — It  raises  and  wrinktes  the  skin  of  the  chin,  and,  consequently,  raises  the  low- 
er lip,  and  projects  it  forward.  It  appears  somewhat  singular  at  first  that  an  elevator  of 
the  lip  should  be  situated  below  it. 

General  Considerations  regai-ding  the  Movements  of  the  Lips,  and  those  of  the 

Face  in  general. 

If  we  take  a  general  view  of  the  muscles  of  the  face,  we  shall  observe,  1.  That  no  re- 
gion is  provided  with  so  great  a  number  of  muscles ;  2.  That  all  these  muscles  are  at- 
tached to  a  bone  by  one  extremity,  while  the  other  is  implanted  into  the  skin,  or  into 
other  muscles ;  3.  That  the  cutaneous  portion  of  these  muscles  is  colourless  and  non- 
fjisciculated,  presenting  all  the  characteristics  of  involuntary  muscles  ;*  4.  That  those 
portions  which  are  attached  either  to  the  bone  or  to  other  muscles  have,  on  the  contrary, 
aH  the  characters  of  the  voluntary  muscles. 

All  these  muscles  are  arranged  around  the  several  openings  of  the  face,  and,  conse- 
quently, they  are  either  constrictors  or  dilators  ;  the  orifice  of  the  mouth,  however,  is 
peculiar!  in  having  the  greater  number  of  the  muscles  of  the  face  specially  intended  for 
it.  Indeed,  the  orbicularis  oris,  or  sphincter  of  the  mouth,  is  antagonized  by  the  bucci- 
nators or  transverse  dilators ;  by  the  proper  elevators  of  the  upper  lip,  and  the  common 
elevators  of  that  and  the  alae  of  the  nose ;  by  the  depressors  of  the  lower  lip,  or  quadrati ; 
by  the  elevators  of  the  angle  of  the  mouth,  viz.,  the  canine  muscles,  the  zygomatici  ma- 
jores,  and,  where  they  exist,  the  zygomatici  minores,  and  the  two  risorii  of  Santorini ; 
and,  lEistly,  by  the  depressors  of  the  commissure,  or  triangulares  oris. 

The  lips  fulfil  a  great  number  of  uses,  all  requiring  a  considerable  degree  of  mobility.  • 
They  serve  for  the  prehension  of  aliments,  for  suction,  and  for  the  articulation  of  soundsj  *' 
whence  the  name  labial  given  to  consonants  specially  produced  by  the  action  of  the  lips, ' 
as  b,  p,  m :  they  modify  the  state  of  the  expired  air  so  as  to  produce  in  it  vibrations  of  a 
peculiar  character,  constituting  the  act  of  whistling  ;  and,  in  this  respect,  they  illustrate 
the  mechanism  of  the  glottis  :  they  assist  in  mastication,  by  retaining  the  food  and  con- 
stantly forcing  it  between  the  teeth :  they  are  also  employed,  during  performances  upon 
wind  instruments,  in  regulating  the  volume  of  the  column  of  air  which  strikes  upon  the 
body  to  be  thrown  into  vibrations.  The  mechanism  of  their  action  varies  according  to 
the  kind  of  instrument :  sometimes,  for  example,  they  assist  in  graduating  the  rapidity 
of  the  column  of  air,  by  influencing  the  orifice  through  which  it  issues,  as  occurs  in  play- 
ing upon  the  flute ;  and  sometimes  they  represent  vibrating  cords  situated  at  the  mouth 
of  an  instrument,  and  determining  the  different  tones  by  their  various  degrees  of  ten- 
sion. In  this  case,  the  lips  themselves  become  the  vibrating  bodies,  and  propagate  their 
oscillations  to  other  bodies  with  which  they  are  in  contact,  independently  of  the  effect 
produced  in  the  instrument  from  the  passage  of  a  column  of  air.  Examples  of  this  are 
observed  in  playing  on  the  horn,  trumpet,  &c. 

If  we  examine  the  muscles  of  the  face  in  connexion  with  their  influence  in  producing 
emotional  expressions,  we  shall  find  that  they  are  often  almost  completely  removed  from 
the  influence  of  the  will,  as,  for  example,  where  those  emotions  are  not  simulated ;  but 
that  sometimes,  on  the  contrary,  their  contraction  is  altogether  voluntary,  as  in  those 
individuals  who,  either  by  profession  or  habit,  are  accustomed  to  imitate  feelings  which 
they  do  not  really  experience.  Nevertheless,  it  should  be  remarked  that,  although  the 
outward  expression  of  every  passion  may  be  produced  at  will  upon  the  face,  yet  there  is 
always  a  great  difference  between  the  natural  emotion  and  the  fictitious  representation. 

On  the  whole,  the  general  expressions  of  the  countenance  may  be  regarded  as  varie- 
ties of  two  great  types,  viz.,  those  of  the  cheerful  and  those  of  the  melancholy  emotions. 

*  This  similarity  is  limited,  however,  to  the  colour  and  general  aspect  of  the  two  kinds  of  muscles ;  for 
even  the  palest  muscular  fasciculi  of  the  face  are  found  to  consist  of  striated  fibres,  precisely  similar  to  those 
of  the  other  voluntary  muscles  ;  but  the  fasciculi  into  which  they  are  collected  are  neither  so  evident  nor  so  large.- 

t  Man  greatly  exceeds  all  animals  in  the  number  of  muscles  attached  to  his  lips.     The  ape,  which  is  ni'"^ 
markable  for  the  great  mobility  of  its  physiognomy,  has,  properly  speaking,  only  one  muscle  for  the  entire  face, 
which  is  a  dependance  of  the  platysma  (or  cutaneous  muscle)  ;  therefore,  the  play  of  its  countenance  is  con- 
fined to  a  grimace,  which  is  always  the  same,  only  differing  in  intensity,  and  which  does  not  permit  it  to  ex 
press  different  and  even  opposite  passions,  such  as  are  often  depicted  upon  the  human  countenance.* 

*  £The  platysma  myoides  in  monkeys  is  certainly  extended,  as  a  single  muscle,  over  the  entire  cheek,  and 
forms  a  muscular  layer,  covering  the  lateral  pouches  appended  to  the  mouth  in  some  of  that  tribe  of  animals. 
In  addition  to  this,  however,  monkeys  have  precisely  the  same  number  of  muscles  attached  to  their  lips  as  in 
the  human  subject :  they  possess,  indeed,  all  the  facial  muscles  found  in  man ;  and,  like  him,  they  appear  to 
be  capal)le  of  expressing,  by  changes  in  their  features,  a  variety  of  internal  emotions.] 


THE    MASSETER.  239 

The  cheerful  emotions  are  expressed  by  the  expansion  of  the  features,  i.  e.,  their  retrac- 
tion from  the  median  line,  a  movement  that  is  due  to  the  occipito-frontalis,  the  levatores 
palpebrarum,  and  especially  to  the  great  zygomatic  muscles.  The  melancholy  passions, 
on  the  contrary,  are  expressed  by  the  approach  or  concentration  of  the  features  towards 
the  median  line,  which  is  chiefly  effected  on  either  side  of  the  face  by  the  corrugator 
supercilii,  the  depressor  anguli  oris,  the  common  and  proper  elevators  of  the  upper  lip, 
the  levator  labii  inferioris,  and  the  quadratus  menti. 

On  account  of  the  intimate  connexion  between  the  skin  of  the  face  and  the  facial  mus- 
cles, which,  from  the  nature  of  their  insertions,  are  in  some  measure  identified  with  it, 
the  frequently-repeated  contraction  of  one  or  more  of  these  muscles  occasions  folds  oi 
wrinkles  of  the  skin  that  remain  during  the  intervals  of  those  contractions,  and  aftei 
they  have  entirely  ceased.  And  thus  the  continual  experience  of  grave  or  cheerful  emo- 
tions, with  their  characteristic  expressions  of  countenance,  at  length  impresses  a  pecu- 
liar and  permanent  stamp  upon  the  features,  so  that  those  who  are  in  the  habit  of  close 
ly  observing  such  circumstances  may  in  some  degree  judge  of  the  disposition  of  an  indi 
vidual  from  an  examination  of  his  physiognomy.  This  is  the  only  foundation  of  the  sys 
tern  of  Lavater. 


MUSCLES  OF  THE  TEMPORO-MAXILLARY  REGION. 
The  Masseter  and  Temporalis. 
The  muscles  of  this  region  are  four  in  niunber ;  two  on  each  side,  viz.,  the  massetei 
and  the  temporal. 

The  Masseter. 

Dissection. — ^Make  a  horizontal  incision  along  the  zygoma,  and  a  vertical  one  from  the 
middle  of  this  to  the  base  of  the  jaw  ;  dissect  back  the  flaps,  taking  care  not  to  divide 
the  Stenonian  duct,  which  passes  over  the  muscle.  In  order  to  see  the  deep  surface,  saw 
through  the  zygoma  in  two  places,  and  turn  it  outward. 

The  masseter  {s,Jig.  113)  is  a  short  and  very  thick  muscle,  of  an  irregularly-quadrilat- 
eral form,  situated  upon  the  side  of  the  face. 

Attachments. — It  arises  from  the  lower  edge  of  the  zygoma,  and  is  inserted  into  the 
outer  surface  of  the  angle  and  ramus  of  the  lower  jaw.  Its  origin  from  the  zygoma 
consists  of  a  very  thick  aponeurosis,  which  embraces  the  anterior  borders  of  the  mus- 
cles, and  is  composed  of  several  planes  of  super-imposed  fibres,  which  are  prolonged 
upon  its  surface  and  in  its  substance  for  a  considerable  distance.  Tlie  fleshy  fibres  pro- 
ceed from  the  inferior  surface  and  the  borders  of  this  aponeurosis,  obliquely  downward 
and  backward,  and  are  inserted  into  the  angle  of  the  jaw  either  directly  or  by  means  of 
very  strong  tendinous  fibres.  Not  unfrequently  a  small  triangular  fasciculus  is  detached 
forward  to  the  inferior  border  of  the  body  of  the  bone.  The  fleshy  fibres  arising  from 
the  posterior  portion  of  the  zygoma  constitute  a  short,  small,  and  almost  entirely  fleshy 
bundle,  which  passes  vertically  downward,  and  is  inserted  behind  the  preceding  into  the 
external  surface  of  the  ramus  of  the  jaw.  Lastly,  the  zygomatic  arch  being  reversed, 
we  see  a  still  smaller  fleshy  fasciculus,  arising  directly  from  its  internal  surface,  and 
T^assmg  forward,  to  be  inserted  into  the  outer  surface  of  the  coronoid  process,  and  into 
the  tendon  of  the  temporal  muscle. 

Relations. — It  is  covered  by  the  skin,  from  which  it  is  separated  by  a  small  fascia,  and 
sometimes  by  a  prolongation  of  the  platysma  ;  behind,  it  is  covered  by  the  parotid  gland, 
and  by  the  orbicularis  palpebrarum  and  zygomaticus  major  above.  It  is  crossed  at  right 
angles  by  the  divisions  of  the  facial  nerve,  the  transverse  artery  of  the  face,  and  the 
Stenonian  duct.  It  covers  the  ramus  of  the  jaw,  the  temporal  and  the  buccinator  mus- 
cles, from  the  latter  of  which  it  is  separated  by  a  collection  of  fat.  Its  anterior  edge, 
which  is  prominent  beneath  the  skin,  has  an  important  relation  below  to  the  facial  ar- 
tery, which  may  be  compressed  against  the  bone  immediately  in  front  of  it.  The  parot- 
id gland  embraces  its  posterior  border. 

Action. — The  action  of  this  muscle  is  very  powerful.  Its  strength  in  different  animals 
may  be  in  some  degree  measured  by  the  size  of  the  zygomatic  arclu  and  by  the  promi- 
nence of  tiie  lines  and  projections  on  the  angle  of  the  jaw. 

Its  momentum,  i.  e.,  its  period  of  most  powerful  action,  occurs  when  the  jaws  are 
slightly  separated,  because  its  angle  of  incidence  with  regard  to  the  lever  is  then  nearly 
perpendicular.  The  general  direction  of  the  fibres  of  the  masseter  muscles,  obliquely 
downward  and  backward,  is  highly  advantageous  as  regards  the  trituration  of  the  food, 
for  during  the  contraction  of  the  two  muscles  the  lower  jaw  is  moved  upward  and  for- 
ward. This  same  obliquity  explains  the  action  of  the  muscle  in  producing  luxation  of 
the  jaw  ;  for  as  its  insertion  is  farther  back  than  it  would  have  been  had  the  fibres  been 
vertical,  it  follows  that,  however  slightly  the  jaws  may  be  separated,  the  condyle  is 
placed  in  front  of  the  axis,  to  which  all  the  fibres  of  the  masseter  may  be  referred ;  and 
when  this  muscle  contracts,  it  increases  the  peculiar  movement  performed  by  the  con- 
dyle in  becoming  dislocated  forward. 


240 


MYOIiOGY. 


The  Temporalis. 

Dissection. — Having  sawn  through  and  turned  back  the  zygoma,  remove  the  fascia 
covering  the  temporal  region,  and  the  fat  surrounding  the  insertion  of  the  muscle  into 
the  coronoid  process.  In  order  to  gain  a  view  of  the  deep  surface,  detach  the  muscle, 
either  from  above  downward,  by  scraping  the  periosteum  from  the  temporal  fossa,  or 
from  below  upward,  after  having  sawn  through  the  base  of  the  coronoid  process. 

The  temporal  muscle  {e',  fig.  114),  or  crotaphyte,  so  named  because  it  occupies  the 
whole  of  the  temporal  fossa  {Kporacjioc,  the  temple),  is  a  broad,  radiated  muscle,  resem- 
bling a  triangle  with  the  base  turned  upward. 

Attachments. — It  arises  from  the  whole  extent  of  the  temporal  fossa,  and  from  the  in- 
ner surface  of  the  superficial  temporal  fascia,  and  is  inserted  into  the  edges  and  summit 
of  the  coronoid  process.  The  fleshy  fibres  all  arise  directly,  either  from  the  temporal 
fossa,  or  from  the  inner  surface  of  the  fascia,  which,  being  attached  above  to  the  entire 
length  of  the  temporal  semicircular  line,  and  below  to  the  upper  edge  of  the  zygomatic 
arch,  is  very  tense,  and  thus  affords  a  solid  and  very  strong  surface  of  origin.  From 
these  two  parts  the  fleshy  fibres  converge,  and  proceeding  downward,  the  anterior  ob- 
liquely backward,  the  posterior  obliquely  forward,  and  the  middle  vertically,  form  a  fleshy 
mass,  which  gradually  increases  in  thickness  until  its  fibres  are  attached,  partly  to  the 
external,  but  chiefly  to  the  internal  surface  and  borders  of  the  terminal  aponeurosis. 
The  fibres  of  this  aponeurosis,  which  are  very  strong,  and  radiated  at  its  comm'ince  - 
ment,  are  collected  into  the  form  of  a  very  thick  tendon,  inserted  into  the  coronoid  pro- 
cess, and  called  the  coronoid  tendon.  The  temporal  muscle,  in  its  course  from  the  tem- 
poral fossa  to  the  coronoid  process,  undergoes  a  sort  of  reflection  over  the  groove  at  the 
base  of  the  zygoma.  I  have  often  seen  a  very  strong  muscular  fasciculus  arising  from 
the  lower  part  of  the  temporal  fossa  and  the  ridge  bounding  it  below,  and  inserted  by  a 
separate  tendon  into  the  internal  border  of  the  anterior  surface  of  the  ramus  of  the  jaw. 
Relations. — It  is  covered  by  the  skin,  the  aponeurosis  of  the  occipito-frontalis,  the  an- 
terior and  superior  auricular  muscles,  the  superficial  temporal  arteries,  veins,  and  nerves, 
and  more  immediately  by  the  superficial  temporal  aponeurosis,  the  zygomatic  arch,  and 
the  masseter.  It  covers  the  temporal  fossa,  the  external  pterygoid  muscle,  a  small 
part  of  the  buccinator,  the  internal  maxillary  artery,  and  the  deep  temporal  vessels.  Its 
thickness  is  in  proportion  to  the  depth  of  the  temporal  fossa  and  the  strength  of  the 
coronoid  process. 

Action. — The  strength  of  the  temporal  muscle,  therefore,  may  be  in  some  degree 
measured  by  the  depth  of  the  temporal  fossa  and  the  size  of  the  coronoid  process.  This 
fact  may  be  demonstrated  by  an  examination  of  these  regions  in  the  skeletons  of  carniv- 
orous animals,  in  which  the  elevators  of  the  lower  jaw  are  most  highly  developed.  The 
use  of  the  temporal  muscle,  like  that  of  the  masseter,  is  to  elevate  the  lower  jaw,  but 
the  mechanism  of  its  action  is  diflerent.  In  fact,  the  masseter  raises  the  jaw  by  a  direct 
action ;  the  temporal  muscle,  on  the  contrary,  raises  it  by  a  sort  of  swing  motion,  acting 
principally  upon  the  back  part  of  the  coronoid  process.  In  a  word,  the  temporal  muscle 
acts  upon  the  vertical  arm  of  the  bent  lever  represented  by  the  maxillary  bone,  while 
the  masseter,  on  the  contrary,  acts  upon  its  horizontal  arm,  the  movement  depending  on 
the  action  of  the  temporal  muscle  :  the  lower  jaw  resembles  the  curved  lever  represent- 
ed by  the  hammer  of  a  beU. 


THE  PTERYGO-MAXILLARY  REGION. 
The  Pterygoideus  Internus. — The  Plerygoideus  Externus. 
The  muscles  of  this  region  are  the  external  and  the  internal  pterygoids. 


Fig.  115 


The  Pterygoideus  Internus  vel  Magnus 

Dissection. — Separate  the  face  and  that  part  of 
the  cranium  which  is  situated  anterior  to  the  ver- 
tebral column  from  the  remainder  of  the  scull, 
and  divide  the  face  into  two  lateral  halves  by  an 
antero-posterior  section. 

'  This  muscle  may  also  be  dissected  in  the  fol- 
lowing manner  :  saw  through  the  lower  jaw  ver- 
tically at  the  junction  of  the  body  and  ramus ;  re- 
move the  zygomatic  arch  ;  cut  through  the  base 
of  the  coronoid  process  and  the  neck  of  the  con- 
dyle, and  then  disarticulate  the  latter. 

The  internal  pterygoid  {a,  fig.  115)  is  deeply 
seated  m  the  zygomatic  fossa,  along  the  inner 
surface  of  the  ramus  of  the  jaw(tertius  nmsculus 
qui  in  ore  latitat,  Vesalius).     It  is  thick  and  quad- 


THE    PTERYGOIDEttS   EXTERNUS,   ETC. 

iilateral,  and  in  its  form,  structure,  and  direction,  bears  a  remarkable  reselrtBlarice  to  the 
masseter ;  hence  Winslow  called  it  the  internal  masseter. 

Attachments. — It  arises  from  the  pterygoid  fossa,  from  the  hamular  process,  at  the  apex 
of  the  internal  pterygoid  plate,  and  from  the  lower  surface  of  the  pyramidal  process  of 
the  palate  bone ;  and  is  inserted  into  the  inner  surface  of  the  angle  of  the  lower  jaw 
Its  origin  consists  of  a  tendon  resembling  that  of  the  msisseter,  prolonged  upon  the  in- 
ternal surface,  and  into  the  substance  of  the  muscle.  From  this  the  fleshy  fibres  pro- 
ceed downward,  outward,  and  backward,  to  be  inserted,  by  very  strong  tendinous  laminae, 
into  the  lower  jaw. 

Relations. — On  the  inside  it  is  in  relation  with  the  external  peristaphyhne  muscle 
{tensor  palcti),  and  with  the  pharynx,  a  triangular  interval  existing  between  it  and  the 
latter,  occupied  by  a  considerable  quantity  of  cellular  tissue,  vessels,  nerves,  and  the 
sub-maxillary  gland :  on  the  outside  it  corresponds  with  the  ramus  of  the  lower  jaw, 
from  which  it  is  separated  above  by  the  dental  and  lingual  nerves,  the  inferior  dental 
vessels,  and  the  so-called  internal  lateral  ligament  of  the  temporo-maxillary  articulation. 

Action. — As  this  muscle  is  inserted  almost  perpendicularly  into  the  lever  upon  which 
it  acts,  it  has  very  great  power.  Most  of  the  remarks  already  made  concerning  the  mas- 
setor  apply  to  this  muscle,  which  is  a  true  internal  masseter.  It  has  only  this  peculiar- 
ity, that  as  its  origin  is  nearer  the  median  line  than  that  of  the  external  masseter,  it 
assists  in  producing  a  slight  lateral  movement  of  the  jaw,  which  is  very  useful  in  bruis- 
ing the  food. 

The  Pierygoideus  Externus  vet  Parvus. 

Dissection. — This,  like  the  preceding  muscle,  may  be  exposed  by  two  opposite  methods. 

The  external  pterygoid  {b,fig.  115)  is  very  short,  thick,  and  conoid,  smaller  than  the 
preceding,  and  situated  in  the  zygomatic  fossa,  extending  horizontally  from  the  outer 
surface  of  the  external  pterygoid  plate  to  the  neck  of  the  condyle  of  the  lower  jaw.  It 
arises  from  the  whole  outer  surface  of  the  external  plate  of  the  pterygoid  process,  and 
from  the  facette  of  the  palatine  process,  at  which  it  terminates  below,  from  the  ridge 
separating  the  temporal  and  zygomatic  fossae,  and  from  a  spinous  process  at  the  extrem- 
ity of  this  ridge,  which  appears  to  me  worthy  of  notice.  It  is  inserted  into  the  fossa  in 
front  of  the  neck  of  the  condyle  of  the  lower  jaw,  and  into  the  border  of  the  interarticu- 
lar  cartilage.  Its  origin  consists  of  a  strong  tendon,  prolonged  into  the  substance  of 
the  muscle.  From  this  the  fleshy  fibres  proceed  horizontally  outward  and  backward, 
forming,  at  first,  two  distinct  portions,  between  which  the  internal  maxillary  artery  often 
pjisses  :  these  two  portions  then  converge,  are  blended  together,  and  terminate  by  some 
small  tendinous  fibres,  which  form  the  truncated  summit  of  the  cone  represented  by  the 
muscle,  and  are  attached  to  the  neck  of  the  condyle  and  to  the  inter-articular  cartilage. 

Relations. — This  muscle  is  deeply  situated,  and  is  in  relation  on  the  outside  with  the 
ramus  of  the  lower  jaw,  the  temporal  muscle,  and  the  internal  mcixillary  artery ;  on  the 
inside  with  the  internal  pterygoid,  and  above  with  the  upper  wall  of  the  zygomatic  fossa. 

Action. — The  axis  of  the  external  pterygoid  being  directed  outward  and  backward, 
and  its  origin  being  at  the  pterygoid  process,  it  may  be  readily  imagined  that  its  con- 
traction will  produce  a  horizontal  motion  in  two  directions,  viz.,  forward  and  to  the  op- 
posite side  from  that  on  which  the  muscle  is  acting.  When  the  two  external  pterygoids 
act  together,  the  jaw  is  carried  directly  forward.  From  the  insertion  of  this  muscle  into 
the  inter-articular  cartilage,  the  latter  is  never  separated  from  the  condyle  during  these 
several  movements.  It  is  principally  this  muscle  which  causes  displacement  of  the  con- 
dyle in  cases  of  fracture  of  the  neck  of  the  bone,  and  it  is  also  the  chief  agent  in  bruis 
ing  the  food. 


MUSCLES  OF  THE  UPPER  EXTREMITIES 

The  muscles  of  the  upper  extremities  may  be  divided  into  those  of  the  shoulder,  oi 
the  ann,  of  the  forearm,  and  of  the  hand. 

MUSCLES  OF  THE  SHOULDER 

The  Deltoidexis. — Supra-spinatus. — Infraspinatus  and  Teres  Minor. — Subscapularis. 

The  muscles  of  the  shoulder  are  the  deltoid,  the  supra-spinatus,  the  infra-spinatus 
and  teres  minor  (which  I  regard  as  only  one  muscle),  and  the  subscapularis.  The  teres 
major,  generally  arranged  among  the  muscles  of  this  region,  has  already  been  described 
with  the  latissimus  dorsi,  of  which  it  may  be  regarded  as  an  accessory. 

The  Deltoideus. 
Dissection. — Make  a  horizontal  incision  through  the  skin,  round  the  summit  of  the 
•houlder,  extending  from  the  external  third  of  the  clavicle  to  the  most  distant  point  of 
the  spine  of  the  scapula :  from  the  middle  of  this  incision  let  another  be  made,  descend- 

Hh 


242  MYOLOGY. 

mg  vertically  half  way  down  the  humerus  ;  dissect  back  the  two  flaps,  taking  care  tc 
raise  at  the  same  time  a  very  thin  aponeurosis,  which  is  closely  applied  to  the  fibres. 

The  deltoid  {I,  figs.  106,  109),  so  named  from  its  resemblance  to  the  Greek  delta,  A,  re- 
versed, is  a  thick,  radiated,  triangular  muscle,  bent  in  such  a  way  as  to  embrace  the 
scapulo-humeral  articulation  before,  on  the  outer  side  and  behind.  It  is  the  muscle  of 
the  top  of  the  shoulder. 

Attachments. — It  arises  from  the  entire  length  of  the  posterior  border  of  the  spine  of 
the  scapula,  from  the  external  border  of  the  acromion,  and  from  the  external  third,  i.  e., 
from  the  concave  part  of  the  anterior  border  of  the  clavicle  :  it  is  inserted  into  the  del- 
toid impression  on  the  humerus.  The  scapulo-clavicular  origin  of  the  deltoid  corre- 
sponds exactly  to  the  inferior  attachment  or  the  insertion  of  the  trapezius,  so  that  these 
two  muscles,  although  separate  and  distinct  in  man,  appear  to  form  a  single  muscle  di- 
vided by  an  intersection  :  a  view  that  is  perfectly  confirmed  by  a  reference  to  compara- 
tive anatomy.  The  origin  consists  of  tendinous  fibres  ;  of  these  the  posterior  are  the 
longest,  and  are  blended  with  the  infra-spinous  aponeurosis,  which  also  gives  origin  to 
some  of  the  fibres  of  the  deltoid.  Three  or  four  principal  tendinous  laminae,  attached  at 
regular  intervals  to  the  clavicle  and  the  acromion,  penetrate  into  the  substance  of  the 
muscle,  and  give  origin  to  a  great  number  of  fleshy  fibres.  The  largest  of  these  laminae 
extends  from  the  summit  of  the  acromion,  and  its  situation  is  sometimes  indicated  by  a 
prominence  of  the  skin,  particularly  during  contraction  of  the  muscle.  From  this  very 
extensive  origin  the  fleshy  fibres  proceed  downward,  the  middle  vertically,  the  anterior 
backward,  and  the  posterior  forward  :  they  form  a  thick,  broad  mass,  moulded  over  the 
top  of  the  shoulder,  and,  gradually  converging,  are  at  length  inserted  into  the  deltoid 
impression  of  the  humerus  by  three  evry  distinct  tendons,  the  two  principal  of  which, 
the  anterior  and  posterior,  are  attached  to  the  bifurcations  of  that  V-shaped  impression. 
Not  unfrequently  some  fibres  of  the  pectoralis  major  are  connected  with  the  front  of  this 
tendon. 

Relations. — It  is  covered  by  the  skin,  the  platysma  intervening  between  them,  by 
some  supra-acromial  nerves,  and  by  a  thin  fascia  extending  from  the  infra-spinous  apo- 
neurosis, the  spine  of  the  scapula  and  the  clavicle,  and  becoming  continuous  with  the 
fascia  of  the  arm.  It  covers  the  shoulder-joint,  from  which  it  is  separated  by  a  tendi- 
nous layer  continued  from  the  infra-spinous  and  coraco-acromial  ligaments,  and  which 
terminates  on  the  sheaths  of  the  coraco-brachialis  and  biceps  muscles.  Between  this 
lamina  and  the  greater  tuberosity  of  the  humerus  there  is  a  quantity  of  filamentous  cel- 
lular tissue,  and  frequently  a  synovial  bursa.  The  deltoid,  therefore,  is  enclosed  in  a 
proper  fibrous  sheath,  and  glides  over  the  articulation.  It  also  covers  the  upper  third 
of  the  humerus,  the  coracoid  process,  the  tendons  of  the  pectorales,  coraco-brachialis, 
biceps,  supra-spinatus,  infra-spinatus  and  teres  minor,  teres  major,  and  biceps  muscles, 
also  the  circumflex  vessels  and  nerves.  The  anterior  border  of  the  deltoid,  directed  ob- 
liquely downward  and  outward,  is  separated  from  the  external  margin  of  the  pectoralis 
major  by  a  cellular  interval,  but  is  frequently  in  contact  with  it.  The  cephalic  vein  and 
a  small  artery  define  the  limits  of  the  two  muscles.  The  posterior  border  is  thin  above, 
where  it  is  applied  to  the  infra-spinatus  muscle,  and  becomes  thick  and  free  below.  The 
inferior  angle  of  the  deltoid  is  embraced  by  the  brachialis  anticus.  Issues  are  generally 
established  over  this  situation. 

Remark. — The  structure  of  this  muscle  has  been  patiently  investigated  by  some  anat- 
omists, who  have  counted  the  exact  number  of  its  component  fasciculi.  Tliese  are  sep- 
arated by  fibro-cellular  prolongations,  like  the  fasciculi  of  the  glutaeus  maximus ;  some- 
times, even,  the  muscle  is  divided  into  three  distinct  portions  above,  viz.,  a  clavicular, 
an  acromial,  and  a  spinal.  Eighteen  or  twenty  small  penniform  fasciculi,  the  bases  of 
which  are  generally  turned  upward,  are  collected  into  a  small  space  by  mutually  over- 
lapping each  other,  and  are  united  by  their  terminating  tendons.  Albinus  admits  ten 
of  these  bundles,  which  he  has  described  separately. 

Action. — The  deltoid  elevates  the  shoulder  (elevator,  attollens  humerum).  From  the 
threefold  direction  of  its  fibres,  it  has  a  different  action,  according  to  the  particular  set  of 
fibres  employed.  The  middle  fibres  raise  the  humerus  directly,  the  anterior  raise  and 
carry  it  forward,  the  posterior  raise  and  carry  it  backward.  When  the  arm  is  raised, 
Bichat  states  that  the  anterior  and  posterior  fibres  can  depress  it ;  but  I  do  not  think 
this  possible.  There  has  been  no  example  recorded  of  luxation  from  the  over-action  of 
this  muscle.  When  the  arm  is  fixed,  as  in  the  act  of  climbing,  the  aJioulder  is  moved 
upon  the  head  of  the  humerus.  The  trapezius  must  be  regarded  as  the  most  powerful 
antagonist  of  the  deltoid,  since  the  scapulo-clavicular  attachments  of  both  muscles  are 
the  same.  Thus,  we  have  seen  that  the  diaphragm  and  the  transversalis  abdominis  are 
separated  only  by  their  costal  insertions.  The  most  complete  antagonism  follows  from 
such  an  arrangement,  for  then  one  fibre  is,  as  it  were,  opposed  to  another,  having  ex- 
actly an  opposite  direction. 

The  action  of  the  deltoid  is,  however,  less  powerfnl  than  might  have  been  supposed 
from  its  size  ;  it  is,  in  fact,  parallel  to  the  lever  on  which  it  acts.  While  almost  all  other 
muscles  have  a  mmnentum,  occurring  at  the  period  when  their  fibres  are  inserted  at  the 


THE  SUPRA  AND  INFRA  S>ilJiATUS  AND  TERES  MINOR.  S48 

most  favourable  angle,  the  deltoid,  pioperly  speaking,  has  none  ;  it  is  parallel  to  the  lever 
during  the  entire  period  of  its  action.  This  is  the  reason  vthy  the  elevation  of  the  arm 
is  so  feeble  a  movement,  and  why  contraction  of  the  deltoid  is  always  accompanied  by 
considerable  fatigue. 

The  Supra-spinatus. 

Dissectimi. — Take  off  the  trapezius,  and,  in  order  to  see  the  whole  extent  of  the  mus- 
cle, remove  the  clavicle,  and  saw  through  the  base  of  the  acromion. 

The  supra-spinatus  {r,fig.  106)  is  a  thick,  triangular  muscle,  broad  on  the  inside,  nar- 
row without,  occupying  the  supra-spinous  fossa,  and  retained  therein  by  a  strong  apo- 
neurosis, which  completes  the  osteo-fibrous  sheath  in  which  the  muscle  is  enclosed. 

Attachments. — It  arises  from  the  internal  two  thirds  of  the  supra-spinous  fossa,  and  is 
inserted  into  the  highest  of  the  three  facettes  on  the  greater  tuberosity  of  the  humerus 
Its  origin  from  the  supra-spinous  fossa  is  partly  tendinous  and  partly  fleshy,  and  sora„ 
fibres  arise  from  its  aponeurotic  investments.  From  these  points  the  fleshy  fibres  con- 
verge to  a  tendon,  which  is  found  among  them  where  the  muscle  reaches  the  upper  part 
of  the  joint,  and  which  is  slightly  reflected  over  the  head  of  the  humerus  before  reaching 
its  insertion.  This  has  not  the  shining  appearance  of  other  tendons,  but  has  the  dull 
aspect  of  many  ligaments  ;  it  is  blended  with  the  fibrous  articular  capsule,  from  which 
it  cannot  be  separated  near  its  insertion.  It  may  even  be  regarded  as  forming  the  upper 
part  of  the  capsular  ligament. 

Relations. — It  is  covered  by  the  trapezius,  the  clavicle,  the  coraco-acromion  ligament, 
and  the  deltoid ;  and  it  covers  the  supra-spinous  fossa,  the  supra-scapular  vessels  and 
nerves,*  and  the  upper  part  of  the  shoulder-joint.  Its  tendon  is  often  blended  with  that 
of  the.  infra-spinatus,  and  is  separated  from  that  of  the  sub-scapularis  by  the  long  head 
of  the  biceps,  and  the  accessory  ligament  of  the  capsule. 

Action. — It  raises  the  humerus,  and  therefore  assists  the  deltoid.  Notwithstanding 
the  nmnber  of  its  fibres,  and  its  perpendicular  insertion  into  its  lever,  it  has  very  little 
power,  on  account  of  the  proximity  of  that  insertion  to  the  fulcrum.  Its  principal  action 
appears  to  me  to  have  reference  to  the  joint,  affording  a  support  to  it  above,  and  forming 
a  sort  of  active  arch,  the  resisting  power  of  which  is  in  proportion  to  the  force  tending 
to  thrust  the  humerus  upward  against  the  osteo-fibrous  arch,  composed  of  the  acromion 
and  coracoid  processes  and  their  connecting  ligament.  There  is  no  muscle,  then,  to 
which  the  name  of  articular  can  be  more  correctly  applied.  The  use  of  the  deep  fibres 
in  preventing  the  folding  of  the  fibrous  and  synovial  capsules,  and  their  compression  be- 
tween the  two  articular  surfaces,  though  much  insisted  on  by  Winslow,  appears  to  me 
very  problematical. 

The  Infra-spinatus  and  Teres  Minor. 

Dissection. — ^Detach  the  scapular  origin  of  the  deltoid,  and  saw  through  the  base  of  the 
acromion. 

The  infraspinatus  (s)  and  teres  minor  {t,  Jig.  106)  constitute  a  single,  thick,  triangular 
aiuscle,  broad  on  the  inside  and  narrow  externally,  and  occupying  the  infra-spinous  fossa, 
in  •rt'hich  it  is  retained  by  an  aponeurosis,  exactly  resembling  that  of  the  supra-spinatus 
uiuscle. 

It  aiises  from  the  internal  two  thirds  of  the  infra-spinous  fossa,  from  a  very  strong 
fascia  interposed  between  it  and  the  teres  major  and  long  head  of  the  triceps,  and  by  a 
'ew  fibres  from  the  infra-spinous  aponeurosis  :  it  is  inserted  into  the  middle  and  inferior 
'acettes  on  the  greater  tuberosity  of  the  humerus,  below  the  insertion  of  the  supra-spi- 
natus. It  arises  from  the  infra-spinous  fossa,  directly  by  fleshy  fibres,  and  also  by  means 
uf  tendinous  fibres  attached  along  the  ridges  of  that  fossa.  One  of  these  laminae  is  con- 
stantly found  attached  to  the  ridge  situated  on  the  outer  side  of  the  infra-spinous  groove  : 
ihis  has  doubtless  given  rise  to  the  division  of  the  muscle  into  two  parts,  called  the  in- 
fra-spinatus and  the  teres  minor.  From  these  origins  the  fleshy  fibres  proceed,  the  su- 
perior horizontally,  the  next  obliquely,  and  the  inferior  almost  vertically  outward  :  they 
form  a  thick,  triangular,  fleshy  body,  and  become  attached  to  the  anterior  surface  and 
margins  of  a  flat  tendon,  which  glides  upon  the  concave  humeral  border  of  the  spine  of 
th,3  scapula,  to  be  inserted  into  the  humerus.  Not  unfrequently  we  find  the  lower  fibres 
of  the  portion  called  the  teres  minor,  arising  from  the  posterior  surface  of  the  tendon  of 
the  triceps,  becoming  applied  to  the  imder  part  of  the  capsular  ligament,  and  inserted 
into  the  humerus  immediately  below  the  great  tuberosity. 

Relations. — These  two  united  muscles  are  covered  by  the  deltoid,  the  trapezius,  the. 
Jatissimus  dorsi,  and  the  skin ;  and  they  cover  the  infra-spinous  fossa,  from  which  they 
are  separated  by  the  supra- scapular  nerves  and  vessels  ;  they  also  cover  the  capsular 
ligament  of  the  joint,  and  a  small  portion  of  the  long  head  of  the  triceps.  Their  lower 
or  external  border  corresponds  internally  or  inferiorly  with  the  teres  major,  an  aponett- 
rotic  septum  intervening  between  them,  and  externally  or  superiorly  with  the  long  head 

jf  the  triceps. 

*  The  supra-scapular  nerve  generally  passes  through  the  coracoid  notch  by  itself,  and  the  supra-scapulat 
lery  above  the  ligament. 


244  •   ?:'.»,«r^  '  MYOLOGY 

Action. — This  muscle  rotates  the  humerus  t,atward  and  a  little  backward.  When  the 
arm  is  raised,  it  assists  in  keeping  it  in  this  position,  and  carries  it  backward.  But  an 
important  use  of  this  muscle  is  that  of  retainmg  the  head  of  the  humerus  in  its  place,  pre- 
venting its  displacement  backward,  and  protecting  the  posterior  part  of  the  articulation. 

The  Sub-scapularis. 

Dissection. — Detach  the  upper  extremity,  including  the  shoulder,  from  the  trunk  of  the 
body  ;  remove  from  the  inner  surface  of  the  muscle  the  cellular  tissue,  the  lymphatic 
glands,  the  brachial  plexus,  the  axillary  vessels,  and  the  serratus  magnus  ;  and  dissect 
off,  with  care,  the  thin  fascia  which  invests  it. 

The  sub-scapularis  (a,  figs.  110,  116)  is  a  thick  triangular  muscle,  occupying  the  whole 
of  the  sub-scapular  fossa,  beneath  the  axillary  border  of  which  it  passes  :  by  itself  it  rep- 
resents the  supra  and  infra  spinatus  and  teres  minor,  upon  the  posterior  scapular  region. 
We  not  unfrequently  meet  with  tendinous  laminae  dividing  it  into  three  parts,  which  cor- 
respond to  those  three  muscles. 

Attachments. — It  arises  from  the  internal  two  thirds  of  the  sub-scapular  fossa,  by  ten- 
dinous laminae  attached  to  the  oblique  ridges  already  described  as  existing  on  that  part 
of  the  scapula  ;  also  from  the  anterior  lip  of  the  axillary  border  of  the  scapula  by  an  apo- 
neurosis, which  separates  this  muscle  from  the  teres  major  and  the  long  head  of  the  tri- 
ceps. Very  frequently  the  lowest  fibres  arise  from  the  anterior  surface  of  this  head  of 
the  triceps,  just  as  we  have  seen  that  the  lower  fibres  of  the  teres  minor  take  their  ori- 
gin from  the  posterior  surface  of  the  same  head  of  that  muscle.  From  these  different 
origins  the  fleshy  fibres  all  proceed  outward,  the  upper  horizontally,  and  the  lower  ob- 
liquely, gradually  approaching  more  and  more  to  the  vertical  direction.  The  muscle, 
therefore,  becomes  progressively  narrower  and  thicker,  until  its  fibres  are  attached  to 
the  two  surfaces  and  borders  of  a  tendon  which  is  inserted  into  the  entire  surface  of 
the  lesser  tuberosity  of  the  humerus.  Some  of  the  muscular  fibres  are  inserted  below 
the  tuberosity ;  and  I  have  seen  the  inferior  fibres  of  the  muscle  attached  for  a  certain 
extent  to  a  fibrous  prolongation  that  completes  the  bicipital  groove  behind. 

Relations. — The  posterior  surface  of  this  muscle  lines  the  sub-scapular  fossa,  which  it 
entirely  fills,  and  from  which  it  is  separated  at  the  outer  third  by  some  cellular  tissue 
and  the  sub-scapular  vessels  and  nerves  ;  more  externally,  it  covers  the  upper  and  anterior 
part  of  the  capsular  ligament  of  the  shoulder-joint,  turning  around  it,  and  becoming  iden- 
tified with  it  at  its  insertion.  Its  anterior  surface  is  in  relation  with  the  serratus  magnus, 
the  sub-scapular  fascia,  and  some  very  loose  cellular  tissue  intervening  between  them ; 
also  with  the  axillary  vessels  and  nerves,  and  with  the  coraco-brachialis  and  deltoid 
muscles.  The  upper  border  of  its  tendon  glides  in  the  hollow  of  the  coracoid  process, 
which  serves  as  a  pulley,  and  forms  with  the  coraco-brachialis  and  the  short  head  of  the 
biceps  a  sort  of  ring,  partly  bony  and  partly  muscular,  in  which  the  tendon  is  retained. 
Between  this  tendon  and  the  coracoid  process  there  is  also  a  synovial  bursa,  which  some- 
times extends  over  the  tendons  of  the  biceps  and  coraco-brachialis,  and  always  commu- 
nicates with  the  synovial  capsule  of  the  shoulder-joint.* 

Action. — It  is  essentially  a  rotator  inward  of  the  humerus.  In  proof  of  this,  we  find 
that  the  muscie  is  stretched  when  the  arm  is  rotated  outward,  and  relaxed  when  it  is  ro- 
tated inward.  The  movement  of  rotation  is  much  more  considerable  than  the  length  of 
the  neck  of  the  humerus  would  lead  us  to  imagine,  and  this  arises  from  the  muscle  turn- 
ing round  the  head  of  the  bone.  As  a  rotator  muscle,  then,  it  is  congenerous  with  the 
latissimus  dorsi.  When  the  humerus  is  raised,  the  sub-scapularis  tends  to  draw  it  down- 
ward. And  farther,  this  muscle,  as  well  as  the  supra-spinatus,  infra-spinatus,  and  teres 
minor,  is  essentially  an  articular  muscle,  and  is  sometimes  completely  identified  with  the 
anterior  part  of  the  fibrous  capsule  :  in  all  cases  it  offers  an  active  resistance  to  displace- 
ment forward,  and  is,  therefore,  always  torn  in  this  kind  of  dislocation. 


MUSCLES  OF  THE  ARM. 
The  Biceps. — Brachialis  Anticus. — Coraco-brachialis. — Triceps  Extensor  Cubiti. 
The  muscles  of  the  arm  have  been  divided  into  those  of  the  anterior  region,  viz.,  the 
biceps,  the  coraco-brachialis,  and  the  brachialis-anticus  ;  and  those  of  the  posterior  region, 
which  constitute  the  single  muscle  called  the  triceps. 

Anterior  Brachial  Region. 
The  Biceps. 
Dissection. — Make  a  vertical  incision  through  the  skin  from  the  middle  of  the  clavicle 
to  the  middle  of  the  bend  of  the  elbow  ;  dissect  back  the  flaps,  and  divide  longitudinally 
the  brachial  fascia,  which  is  united  to  the  biceps  by  very  loose  cellular  tissue  ;  preserve 
the  vessels  and  nerves  which  lie  along  the  inner  border  of  the  muscle.  Expose  the  up- 
per part  of  the  muscle  by  detaching  the  pectoralis  major  and  deltoid  from  their  clavicu- 

*  See  note,  p.  22. 


THE    BICEPS. 


Fig.  116. 


tax  origins,  and  turning  them  inward  and  outward.  In  order  to  trace  the  whole  extent 
of  the  long  head  of  the  biceps,  open  the  capsular  ligament  above  ;  and  to  see  the  radial 
insertion  of  the  muscle,  flex  the  forearm  to  a  right  angle  upon  the  arm,  and  supinate  it 
forcibly ;  it  is  better,  however,  to  wait  until  the  muscles  of  the  anterior  region  of  the  fore- 
arm are  dissected. 

The  biceps  flexor  cubiti  (a,  flg.  116)  is  along  muscle  forming  the  superficial  layer  of  the 
anterior  region  of  the  arm ;  it  is  divided  above  into  a  short  and 
long  head  ;*  and  hence  its  name  biceps. 

Attachmcjits. — It  arises  by  its  short  head  from  the  apex  of  the 
coracoid  process,  and  by  its  long  head  from  the  top  of  the  glenoid 
cavity ;  and  is  inserted  into  the  bicipital  tuberosity  of  the  radius. 

The  origin  of  the  short  or  coracoid  head  {b,fig.  116)  consists 
of  a  flat  and  very  thick  tendon,  common  to  it  and  the  coraco- 
brachialis,  and  terminating  in  front  of  this  part  of  the  muscle  in 
an  aponeurosis,  from  which  is  given  off  a  tendinous  septum,  be- 
tween the  biceps  and  the  coraco-brachialis.  The  long,  glenoid, 
or  reflected  head  arises  by  a  tendon  apparently  forming  a  contin- 
uation of  the  glenoid  articular  border,  which  penetrates  into  the 
interior  of  the  joint,  turns  over  the  head  of  the  humerus,  upon 
which  it  is  reflected,  and  thus  reaches  the  bicipital  groove.  It 
is  retained  in  this  groove  by  a  sort  of  fibrous  bridge  or  canal, 
traverses  the  whole  of  its  extent,  and  ends  in  a  sort  of  tendinous 
cone  open  behind,  from  the  interior  of  which  the  fleshy  fibres 
take  their  origin.  These  fibres  are  collected  into  a  rounded  belly, 
which,  about  the  middle  of  the  arm,  is  applied  to  the  muscular 
belly  of  the  short  portion,  equally  rounded  and  of  variable  size, 
and  ultimately  becomes  identified  with  it.  The  single  muscle 
(fl,  fig.  116)  thus  formed  is  very  thick,  flattened  from  before 
backward,  and  directed  vertically  like  the  two  original  fasciculi. 
Its  fibres  are  attached  to  the  surfaces  and  edges  of  an  aponeuro- 
sis, which  gradually  becomes  narrower  and  thicker,  until  it  emerges  in  the  form  of  a  free 
tendon  opposite  the  lower  end  of  the  humerus,  a  little  nearer  to  the  outer  than  the  inner 
side.  This  flattened  tendon  sinks  downward  and  backward  into  the  triangular  space  be- 
tween the  supinator  longus  and  the  pronator  teres,  and  is  then  so  folded  and  twisted  upon 
itself  that  its  anterior  surface  becomes  posterior,  its  internal  margin  becomes  anterior, 
and  its  external  margin  at  first  posterior  and  then  superior.  This  folding  and  torsion  are 
of  extreme  utility  in  preventing  displacement  of  the  muscle,  which  thus  fastens  down  it- 
self The  tendon  of  insertion  having  given  off  from  its  anterior  surface  and  external 
margin  a  broad  aponeurosis,  constituting  the  principal  origin  of  the  fascia  of  the  fore- 
arm, glides  over  the  bicipital  tuberosity  of  the  radius,  from  which  it  is  separated  by  a 
bursa,  and  is  inserted  into  the  posterior  part  of  that  process. 

Relations. — The  upper  third  of  the  two  heads  of  the  biceps,  as  well  as  the  coraco-brach- 
ialis, and  the  axillary  vessels  and  nerves,  are  contained  in  the  cavity  of  the  axilla,  be 
tween  the  pectoralis  major  and  the  deltoid  in  front,  and  the  latissimus  dorsi  and  teres 
major  behind.  In  this  part  of  its  course,  the  short  head  of  the  biceps  is  in  relation  Witt 
the  coraco-brachialis  on  the  inside,  and  behind  with  the  sub-scapularis,  which  separates 
it  from  the  shoulder-joint ;  a  bursa  intervenes  between  these  two  muscles.  The  tendon 
of  the  long  head  is  in  contact  with  the  head  of  the  humerus,  and  surrounded  by  the  sy- 
novial membrane,  which  isolates  it  from  the  cavity  of  the  joint,  and  accompanies  it,  for 
a  greater  or  less  distance,  along  the  bicipital  groove.  Below  the  axilla  the  biceps  is  sub- 
cutaneous in  front,  the  brachial  fascia  intervening  between  it  and  the  skin,  through  which 
it  is  very  clearly  defined ;  behind,  it  is  in  relation  with  the  musculo-cutaneous  nerve,  and 
the  coraco-brachialis  and  brachialis  anticus  muscles  ;  on  the  inside,  with  the  brachial  ar- 
tery and  its  accompanying  veins,  and  with  the  median  nerve,  all  of  which  lie  along  its  in- 
ternal border,  by  the  projection  of  which  they  are  protected.  The  tendon  is  embraced  at 
its  insertion  by  the  supinator  brevis,  and  it  is  separated  from  that  of  the  brachialis  anti- 
cus by  a  bursa.  Great  attention  should  be  paid  to  the  relation  of  this  muscle  to  the  brach- 
ial artery.  I  am  accustomed,  when  speaking  of  the  surgical  anatomy  of  these  parts, 
to  call  the  biceps  the  satellite  muscle  of  the  brachial  artery.  It  is  worthy  of  remark,  that 
the  relative  positions  of  the  long  and  the  short  head  are  altered  as  the  humerus  is  rota- 
ted inward  or  outward ;  in  rotation  inward,  the  long  head  is  placed  behind  the  other,  or 
even  crosses  to  the  inner  side  of  it ;  but  in  rotation  outward,  the  interval  between  the 
two  heads  is  considerably  increased. 

Action. — The  biceps  flexes  the  forearm  upon  the  arm,  and  at  the  same  time  supinates  it. 
This  last  effect  results  from  the  insertion  of  the  muscle  into  the  inner  and  back  part  of 
the  bicipital  tubercle  of  the  radius.     The  momentum  of  the  biceps  occurs  during  seini- 

*  Not  unfrequently  the  biceps  is  trifid  above.  The  supernumerary  head  is  internal,  and  arises  from  the  in- 
ner border  of  the  humerus,  below  the  coraco-brachialis,  which  may  be  regarded  as  the  continuation  of  this 
head,  for  they  correspond  in  size.  This  supernumerary  portion  is  attached  to  the  inner  edge  and  posterior 
surface  of  the  lower  tendon  of  the  biceps.     1  have  twice  seen  this  disposition  of  parts. 


246  MYOLOGY. 

flexion  of  the  forearm  •  its  insertion  being  at  that  period  perpendicular  to  tiie  lever,  the 
disadvantage  arising  from  its  proximity  to  the  fulcrum  is  then  counteracted.  The  length 
of  Its  fibres  explains  the  extent  of  the  movement  of  flexion.  By  means  of  its  scapular 
attachments,  the  biceps  acts  upon  the  arm,  either  secondarily,  after  bending  the  forearm, 
or  primarily,  when  the  forearm  is  extended.  By  means  of  both  its  heads,  it  carries  the 
arm  forward,  and  thus  co-operates  with  the  anterior  fibres  of  the  deltoid  and  coraco-brach- 
ialis.  The  two  heads  also  assist  in  strengthening  the  shoulder-joint.  The  long  head 
forms  a  sort  of  fibrous  arch,  which  supports  the  head  of  the  humerus,  and  retains  it  in  the 
glenoid  cavity.  The  short  head,  together  with  the  coraco-brachialis,  forms  a  continuation 
of  the  hook  of  the  coracoid  process,  and  protects  the  anterior  and  inner  part  of  the  joint. 

The  biceps  is,  as  Winslow  first  showed,  one  of  the  principal  supinators  of  the  forearm ; 
and  it  is  in  this  movement  that  the  tendon  glides  over  the  bicipital  tuberosity  of  the  ra- 
dius by  means  of  the  intervening  bursa.  This  tuberosity  is  almost  entirely  intended  for 
the  tendon  to  glide  over  ;  it  is,  therefore,  incrusted  with  cartilage.  Dense  and  reddish 
granulations,  as  pointed  out  by  Haller,  are  found  upon  the  synovial  bursa  of  the  tendon. 

When  the  forearm  is  fixed,  as  in  climbing,  the  biceps  flexes  the  arm  upon  the  fore- 
arm, and  the  scapula  upon  the  arm.  Lastly,  it  is  a  tensor  of  the  fascia  of  the  forearm, 
upon  which  the  internal  fibres  of  the  muscle  often  terminate. 

The  Brachialis  Anticus. 

Dissection. — Cut  the  biceps  across,  opposite  the  insertion  of  the  deltoid,  and  turn  down 
the  lower  part  upon  the  forearm. 

The  brachialis  anticus  (brachialis  internus,  Alb.,  d  d,fig.  116;  d,fig.  117)  is  a  thick, 
prismatic,  and  triangular  muscle,  situated  behind  the  preceding.  It  arises  from  the  hu- 
merus, below  the  insertion  of  the  deltoid,  which  it  embraces  by  a  well-marked  bifurca- 
tion ;  and  since  the  point  of  insertion  of  the  deltoid  is  not  always  the  same,  it  follows  that 
this  origin  of  the  brachialis  anticus  is  eilso  variable  ;  it  also  arises  from  the  internal  and 
external  surfaces,  and  from  the  three  borders  of  the  humerus,  and  from  the  external  and 
internal  inter-muscular  septa.  It  is  inserted  into  the  rough  surface  on  the  fore  part  of  the 
coronoid  process  of  the  ulna.  The  different  origins  from  the  humerus  are  fleshy,  the 
fibres  being  of  very  various  lengths,  and  proceeding  in  different  directions  ;  the  middle 
pass  vertically  downward,  the  external  somewhat  obliquely  inward,  and  the  internal  out- 
ward ;  they  all  terminate  on  the  posterior  surface  of  an  aponeurosis,  which  is  broad  and 
thin  above,  and  thick  below,  especially  on  the  outer  side,  where  it  turns  round  so  as  to 
embrace  the  outer  border  of  the  muscle,  and  forms  a  deep  aponeurotic  lamina.  The 
fleshy  fibres,  therefore,  are  received  into  a  semi-cone  of  tendinous  substance,  open  on 
Che  inside,  the  fibres  of  which  are  collected  together,  and  finally  inserted  into  an  oblique 
line,  running  downward  and  outward,  below  the  coronoid  process  of  the  ulna. 

Relations. — The  anterior  surface  of  the  brachialis  anticus  is  in  relation  with  the  biceps, 
the  musculo-cutaneous  nerve,  the  brachial  fascia,  the  brachial  artery  and  veins,  and  the 
median  nerve  ;  its  internal  surface,  with  the  pronator  teres  muscle,  the  ulnar  nerve,  and 
the  triceps,  from  which  it  is  only  separated  by  the  internal  inter-muscular  septum  ;  its 
external  surface,  with  the  supinator  longus  and  the  extensor  carpi  radialis  longior,  which 
are  received  into  a  sort  of  groove  presented  by  it,  the  radial  nerve  establishing  the  limit 
between  these  two  muscles  and  the  brachialis  anticus.  The  posterior  surface  embraces 
the  internal  and  external  surfaces  of  the  humerus,  to  which  it  is  attached ;  below,  it  em- 
braces, and  effectually  protects  the  front  of  the  elbow-joint,  into  the  anterior  ligament  of 
which  many  of  its  fibres  are  inserted. 

Action. — The  brachialis  anticus  flexes  the  forearm  upon  the  arm,  and,  reciprocally,  the 
arm  upon  the  forearm.  Its  momentum  takes  place,  like  that  of  the  biceps,  during  semi- 
flexion. It  is  worthy  of  remark,  that  this  muscle  acts  with  greater  precision  than  the  bi- 
ceps upon  the  forearm,  because  it  arises  from  the  humerus  only,  and,  besides  that,  it  be- 
longs more  especially  than  that  muscle  to  the  elbow-joint.  I  have  already  said  that  it 
may  be  regarded  as  the  active  anterior  ligament  of  this  articulation.  In  fact,  it  so  com- 
pletely hmits  the  movement  of  extension,  that  we  cannot  imagine  the  possibility  of  lux- 
ation of  the  forearm  backward  without  rupture  of  this  muscle.  From  the  insertion  of 
the  biceps  into  the  radius,  and  of  the  brachialis  anticus  into  the  ulna,  it  follows  that  the 
flexor  muscles  of  the  forearm  are  divided  between  the  two  bones,  in  the  same  manner 
as  those  of  the  leg  are  distributed  to  the  tibia  and  fibula  Thus,  the  contraction  of  the 
brachialis  anticus  has  a  tendency  to  carry  the  forearm  outward  as  well  as  to  flex  it, 
while  that  of  the  biceps  tends  to  draw  it  inward.  When  the  two  muscles  contract  si- 
multaneously, direct  flexion  is  the  result. 

The  Coraco-brachialis. 

Dissection. — The  upper  part  is  exposed  as  soon  as  the  deltoid  is  detached  ;  the  middle 
is  situated  between  the  pectoralis  major  and  the  latissimus  dorsi ;  and  the  lower  part  is 
seen  upon  the  mner  surface  of  the  humerus,  near  the  tendon  of  the  deltoid. 

The  coraco-brachialis  {e,figs.  116,  117)  is  the  smallest  muscle  of  the  arm.  It  is  situa- 
ted at  the  inner  and  upper  part  of  the  arm,  and  was  confounded  by  most  of  the  oldei 


THE    TRICEPS    EXTENSOR    CUBITI. 


«4T 


anatomists  with  the  short  head  of  the  biceps,  with  which,  indeed,  it  is  intimately  united 
at  its  upper  part. 

Attachments. — It  arises  from  the  apex  of  the  coracoid  process,  and  is  inserted  towards 
the  middle  of  the  internal  surface  and  border  of  the  humerus.  It  arises  from  between 
two  tendinous  layers,  the  most  superficial  of  which  is  common  to  it  and  the  short  head 
of  the  biceps,  and  also  from  the  septum  between  these  two  muscles.  From  this  origin 
the  fleshy  fibres  proceed,  forming  an  elongated,  thin,  and  flat  bundle,  the  size  of  which  is 
always  in  an  inverse  ratio  to  that  of  the  short  head  of  the  biceps  ;  this  bundle  passes 
downward,  backward,  and  a  little  outward,  to  be  inserted  into  the  humerus,  between  the 
brachialis  anticus  and  the  triceps.  Its  insertion  is  effected  by  means  of  a  flat  tendon, 
which  receives  the  fleshy  fibres  successively  upon  its  edges  and  external  surface,  and  is 
accompanied  by  them  even  to  its  attachment  to  the  bone.  The  precise  situation  of  the 
attachment  varies  like  that  of  the  deltoid,  and  hence  the  different  statements  of  authors 
regarding  this  point.  According  to  Winslow,  the  coraco-brachialis  is  inserted  at  the  up- 
per part  of  the  middle  third  of  the  humerus ;  according  to  M.  Boyer,  in  the  middle  of  the 
bone  ;  and  according  to  Bichat,  a  little  above  its  middle.  I  have  found  it  inserted  at 
the  junction  of  the  lower  with  the  two  upper  thirds. 

Relations. — It  is  covered  by  the  deltoid,  the  pectoralis  major,  and  the  biceps,  and  it 
covers  the  sub-scapularis,  the  latissimus  dorsi,  and  the  teres  major.  Its  relations  to  the 
axillary  and  brachial  arteries,  and  the  median  and  musculo-cutaneous  nerves,  are  the 
most  important.  Above,  it  covers  these  parts,  and  then  it  is  in  relation  with  the  outer 
side  of  the  brachial  artery  and  median  nerve,  so  that  its  tendon  alone  separates  the  ves- 
sel from  the  bone.  The  musculo-cutaneous  nerve  passes  through  it ;  hence  the  name 
of  -perf mains  Casserii  has  been  given  to  this  muscle.  It  is  also  very  frequently  perfora- 
ted by  one  of  the  branches  of  origin  or  roots  of  the  median  nerve. 

Action. — It  cames  the  arm  forward  and  inward,  and,  at  the  same  time,  elevates  it 
It  co-operates  with  the  anterior  fibres  of  the  deltoid,  and  the  superior  fibres  of  the  pecto- 
ralis major.  If  the  arm  be  fixed,  it  depresses  the  top  of  the  shoulder  ;  when  the  arm  is 
carried  backward  and  turned  inward,  it  draws  it  forward  again,  and  rotates  it  outward.* 

Posterior  Brachial  Region. 

The  Triceps  Extensor  Cubiti. 

Dissection. — It  is  exposed  by  simply  removing  the  skin  and  the  fascia  from  the  back 
of  the  arm,  by  removing  the  deltoid,  or  turning  it  upward,  and  by  tracing  the  long  head 
of  the  muscle  between  the  teres  major  and  minor  to  the  axillary  border  of  the  scapula. 
In  order  to  render  it  tense,  and  thus  facilitate  the  dissection,  the  forearm  must  be  flexed 
and  the  humerus  abducted. 

The  triceps  extensor  cubiti  {ifg,fig.  117)  is  a  very  large  muscle,  divided  above  into  three 
portions,  named  the  external,  internal,  and  middle,  or 
long  heads.     It  constitutes  by  itself  the  entire  muscular 
apparatus  of  the  posterior  region  of  the  arm. 

Attachments. — It  arises,  1.  By  its  long  head,  from  the  low- 
er part  of  the  glenoid  cavity  of  the  scapula,  and  from  a 
rough,  triangular  depression  existing  on  the  contiguous 
portion  of  its  axillary  border ;  2.  By  its  external  head 
(vastus  extemus),  from  all  that  portion  of  the  posterior 
surface  of  the  humerus  which  is  above  the  groove  for  the 
radial  nerve,  from  the  external  border  of  that  bone,  and 
from  the  external  inter-muscular  septum ;  3.  By  its  inter- 
nal head  (vastus  intemus),  from  the  whole  of  the  poste- 
rior surface  of  the  humerus  below  the  groove  for  the  ra- 
dial nerve,  from  the  internal  border  of  the  bone,  and  from 
the  internal  inter-muscular  septum.  It  is  inserted  into 
the  back  of  the  olecranon. 

The  origin  of  the  middle  or  long  head  (which  we  shall 
find  to  be  analogous  to  the  rectus  cruris)t  consists  of  a 
tendon  that  is  blended  with  the  glenoid  ligament,  nearly 
in  the  same  manner  as  the  long  tendon  of  the  biceps. 
This  tendon  is  flattened  from  before  backward,  and  soon 
splits  into  two  layers,  united  by  their  outer  edges,  the 
posterior  of  which  is  thin  and  short,  while  the  anterior 
is  very  thick,  especially  at  its  outer  edge,  and  prolonged 
to  the  middle  of  the  muscle.  The  head  of  the  humerus, 
therefore,  is  bound  by  the  long  head  of  the  triceps  below, 
in  the  same  manner  as  by  the  long  tendon  of  the  biceps 

*  I  have  seen  a  small  supernumerary  coraco-brachialis  extending  from  the  base  of  the  corait't  ."v**.^ 
below  the  lesser  tuberosity  of  the  humerus,  immediately  beneath  the  insertion  of  the  sub-scapularis  :  the  same 
arrangement  existed  on  both  sides.     This  small  muscle  described  a  curve  in  front  of  the  sub-soapularis. 

t  The  older  anatomists  regarded  this  long  portion  as  a  separate  muscle  :  longus  [Riolanus  Albirms),  cubitum 
Rxtendentium  primus  (Yesalius),  le  grand  ancone  (Winslow). 


248  a!Y'):,'|(;y. 

above.  The  fleshy  fibres  arise  from  between  the  two  layers  above  mea^.o.icu,  and  form 
a  bundle  flattened  in  front  and  behind,  which  irnmediately  turns  upon  itself,  so  that  its 
anterior  surface  becomes  posterior,  and  vice  versa.  From  this  sort  of  torsion  the  strong- 
est layer  of  the  tendon,  which  was  originally  in  front,  eventually  occupies  the  posterior 
surface  of  the  muscle.  The  fleshy  fibres  arising  from  between  the  two  layers,  and  es- 
pecially from  the  anterior  surface  and  borders  of  the  now  posterior  tendon,  pass  down- 
ward and  a  little  outward,  to  be  inserted,  some  into  the  anterior,  but  the  greater  number 
into  the  posterior  surface  of  an  aponeurotic  expaosion,  the  external  border  of  which  is 
continuous  with  a  similar  structure  belonging  to  the  external  division  of  the  muscle. 
The  aponeurotic  fibres  are  collected  together  into  a  very  thick  tendon,  which  is  folded 
into  a  semi-cone,  within  which  the  fleshy  fibres  terminate  ;  the  tendon  itself  is  inserted 
by  a  thick  mass  into  the  inner  and  back  part  of  the  olecranon,  on  the  outer  side  of  the 
internal  portion  of  the  muscle,  and  closely  united  with  the  posterior  aponeurosis  of  the 
external  portion.    A  synovial  capsule  intervenes  between  this  tendon  and  the  olecranon. 

The  origins  of  the  external  and  internal  portions  from  the  humerus  divide  between 
themselves,  so  to  speak,  the  posterior  surface  of  that  bone,  to  which  the  long  head  has 
no  attachments. 

The  external  head  {f,figs.  116, 117),  which  is  larger  than  the  internal,  and,  from  analo- 
gy, may  be  termed  the  vastus  externus  of  the  triceps  brachii  (cubitum  extendentium  secun- 
dus,  Vesalius ;  ancon6  externe,  Winslow),  arises  partly  by  fleshy  and  partly  by  tendinous 
fibres.  They  are  bounded  above  by  a  rough  line,  which  is  very  well  marked  in  powerful 
individuals,  extending  obliquely  from  the  lower  part  of  the  head  of  the  humerus  to  its 
external  border.  From  these  different  origins  the  fleshy  fibres  proceed  dovnward  and 
inward,  become  partly  blended  with  the  internal  head,  and  are  almost  all  attached  to  the 
anterior  surface  of  the  terminal  aponeurosis  of  the  long  head,  and  to  the  anterior  sur- 
face and  external  edge  of  a  very  broad  and  strong  tendon,  which  occupies  the  posterior 
aspect  of  the  muscle.  This  latter  tendon  is  united  internally  with  the  tendon  of  the  long 
head,  is  folded  upon  itself,  and  receives  the  fleshy  fibres  as  far  as  its  insertion  into  the 
olecranon,  on  the  outside  of  the  long  head.  The  inferior  fleshy  fibres  of  this  portion  of 
the  muscle  are  very  short  and  horizontal,  and  seem  to  be  continued  by  the  anconeus. 

The  internal  head  of  the  triceps  (tertius  cubitum  extendentium,  Vesalius ;  ancone  in- 
terne, Winslow,  g,  figs.  116,  117),  which  we  denominate  the  vastus  internus  of  the  triceps 
brachii,  might  be  called  the  deep  and  internal  portion  of  this  muscle,  for,  as  we  find  with 
regard  to  the  vastus  internus  of  the  thigh,  it  is  almost  entirely  covered  by  the  other  two 
portions.  Its  origins  are  partly  fleshy  and  partly  tendinous.  The  fibres  pass  in  differ- 
ent directions,  the  external  downward  and  inward,  a  few  to  the  anterior  surface  of  the 
aponeurosis  of  the  external  head,  by  which  they  are  concealed,  but  the  greater  number 
directly  to  the  olecranon,  in  front  of  the  insertion  of  the  other  portions.  The  internal 
pass  downward  and  outward,  and  terminate,  some  upon  the  inner  edge  and  anterior  sur- 
face of  the  tendon  of  the  long  head,  but  the  greater  number  directly  upon  the  olecranon, 
to  the  inside  of  that  tendon.  The  lowest  of  these  fibres  are  almost  horizontal.  Somt 
of  the  deepest  fasciculi  are  generally  given  off  from  the  body  of  the  muscle,  to  be  insert- 
ed into  the  synovial  capsule  of  the  elbow-joint. 

Relations. — It  is  covered  through  nearly  its  whole  extent  by  the  brachial  fascia,  and 
separated  by  it  from  the  skin,  through  which  it  is  distinctly  defined ;  it  covers  the  poste- 
rior surface  of  the  humerus,  the  back  of  the  elbow-joint,  the  radial  nerve,  and  the  deep 
humeral  artery.  It  is  separated  from  the  muscles  of  the  anterior  region  of  the  arm  by 
the  external  and  internal  inter-muscular  septa.  Its  long  or  scapular  portion  is  in  relation 
with  the  deltoid  and  the  teres  minor  behind,  and  with  the  sub-scapularis,  the  teres  major, 
and  the  latissimus  dorsi  in  front. 

Action. — The  triceps  extends  the  forearm  upon  the  arm,  but  in  order  that  its  long  head 
may  act  with  effect,  the  scapula  must  be  fixed  by  other  muscles.  The  power  of  this 
muscle  is  not  so  great  as  its  size  and  the  number  of  its  fibres  would  indicate,  on  account 
of  its  disadvantageous  insertion  near  the  fulcrum.  It  is  true  that  here,  as  in  the  case 
of  the  triceps  femoris,  nature  has,  as  much  as  possible,  counterbalanced  this  disadvan- 
tage by  inserting  the  muscle,  not  into  the  apex,  but  into  the  back  part  of  the  olecranon. 
We  even  find,  as  we  have  said,  a  synovial  bursa  between  the  tendon  and  that  part  of  the 
olecranon  with  which  it  is  in  contact.  It  would  appear,  at  first  sight,  that  the  momentum 
of  this  muscle  would  occur  during  semi-flexion,  but  a  little  consideration  would  show 
that,  like  the  triceps  femoris,  it  has,  properly  speaking,  no  momentum  ;  and  that  the  ole- 
cranon, which  may  be  regarded  as  the  ossified  tendon  of  the  muscle,  always  has  the  same 
relation  to  the  ulna,  whatever  be  the  position  of  the  forearm.  It  should  also  be  observ- 
ed, that  this  muscle  has  not  nearly  so  much  power  during  semi-flexion  as  during  exten- 
sion, because,  in  the  former  case,  it  is  opposed  by  the  flexor  muscles,  which,  in  that  po- 
sition, act  with  the  greatest  possible  effect ;  while  in  the  latter,  when  the  arm  and  fore- 
arm form  an  obtuse  angle,  the  extensor  muscle  has  the  advantage.  Lastly,  the  predom- 
inance of  the  extensor  over  the  flexors  is  less  marked  in  the  arm  than  in  the  thigh  ;  and 
even  supposing  the  extensor  to  possess  more  intrinsic  power,  it  has  less  active  force, 
in  consequence  of  the  insertions  of  the  flexors  being  much  more  favourable,  both  as 


THE    PRONATOR    TERES. 


349 


legards  their  distance  from  the  fulcrum,  and  their  nearer  approach  to  a  perpendicular 
direction.  Thus  flexion  evidently  predominates  at  the  elbow,  and  extension  at  the  knee. 
This,  indeed,  ought  to  be  the  case,  for  in  the  upper  extremities  the  flexion  of  the  elbow 
is  the  movement  of  attraction  and  prehension ;  while  in  the  lower  extremities,  the  ex- 
tension of  the  knee  is  an  essential  position  in  standing,  walking,  running,  and  leaping. 

We  might  suppose  the  possibility  of  rupture  of  the  olecranon  at  its  junction  with  the 
coronoid  process,  during  violent  extension  o{  the  forearm,  an  accident  that  would  be  anal- 
ogous to  fracture  of  the  patella,  or  rupture  of  its  ligament.  The  long  head  of  the  tricepa 
assists  in  drawing  the  humerus  backward,  and  slightly  adducts  the  arm.  By  means  oi 
its  tendon  of  origin  from  the  scapula,  and  especially  by  the  outer  edge  of  that  tendon, 
which  is  thick,  and,  £is  it  were,  arched,  so  as  to  fit  the  head  of  the  humerus,  the  long 
head  also  forms  a  cord  which  supports  the  bone  during  abduction,  and  tends  to  prevent 
its  displacement ;  but,  as  the  glenoid  cavity  is  directed  forward,  and  as  its  inferior  ex- 
tremity is  situated  almost  at  the  junction  of  the  two  anterior  thirds  with  the  posterior 
third  of  the  cavity,  it  follows  that  this  tendon  is  well  calculated  to  prevent  dislocation 
backward,  but  offers  no  resistance  to  displacement  forward.  Sometimes  the  lower  ex 
tremity  of  the  triceps  becomes  its  fixed  point,  and  then  it  extends  the  arm  upon  the  fore- 
arm, and  the  shoulder  upon  the  arm. 


MUSCLES  OF  THE  FOREARM. 


Fig  118. 


The  Pronator  Teres. — Flexor  Carpi  Radialis. — Palmaris  Longus. — Flexor  Carpi  Ulnaris. 
— Flexor  Sublimis  Digitorum. — Flexor  Profundus  Digitorum. — Lumbricalcs. — Flexor 
Longus  Poinds. — Pronator  Quadratus. — Supinator  Longus. — Extensores  Carpi  Radia- 
lis, Longior  et  Brevior. — Supinator  Brevis. — Extensor  Communis  Digitorum. — Extensor 
Digiti  Minimi. — Extensor  Carpi  Ulnaris. — Anconeus. — Abductor  Longus  Pollicis. — Ex- 
tensor  Brevis  Pollicis. — Extensor  Proprius  Indicis. 

The  muscles  of  the  forearm  are  divided  into  those  of  the  anterior,  the  external,  and 
the  posterior  regions. 

Muscles  of  the  Anteeior  Region. 
These  muscles  form  four  very  distinct  layers.     The  first  consists  of  the  pronator  teres, 
the  flexor  carpi  radialis,  the  palmaris  longus,  and  the  flexor  carpi  ulnaris  ;  the  second  is 
formed  by  the  flexor  sublimis  digitorum ;  the  third  by  the  flexor  profundus  digitorum  and 
the  flexor  longus  pollicis  ;  and  the  fourth  by  the  pronator  quadratus. 

The  Pronator  Teres. 

Dissection. — This  muscle  is  exposed  when  the  inner  and  anterior  part  of  the  fascia  of 
the  forearm  is  removed.     Its  origin  should  be  carefully  studied. 

The  pronator  teres,  or  rotundus  {a,  fig.  118),  the  most  superficial  mus- 
cle on  the  anterior  and  inner  aspect  of  the  forearm,  forms  an  oblique 
ridge  under  the  skin,  upon  the  inner  side  of  the  bend  of  the  elbow. 
It  is  attached  above  to  the  inner  condyle  of  the  humerus,  or  epitroch- 
lea  (a,  fig.  1 19),  and  is  inserted  below  into  the  middle  of  the  radius  (a')- 
It  arises  from  the  lower  part  of  the  inner  border  of  the  humerus,  from 
the  inner  condyle,  from  a  large  inter-muscular  septum,  separating  it 
from  the  flexor  carpi  radialis  and  the  flexor  sublimis,  and  from  the 
coronoid  process  of  the  ulna  on  the  inner  side  of  the  brachialis  anti- 
cus,  by  means  of  a  tendinous  and  fleshy  bundle,  which  is  separated 
from  the  rest  of  the  muscle  by  the  median  nerve.  From  these  ori- 
gins the  fleshy  fibres  proceed  obliquely  downward  and  outward  (pro- 
nateur  oblique,  Winsl.),  surrounding  a  flat  tendon,  which  appears  first 
on  the  anterior  surface  of  the  muscle,  and  then  turns  over  the  ante- 
rior and  external  surfaces  of  the  radius,  to  be  inserted  at  the  middle 
of  that  bone.  The  muscle,  therefore,  turns  spirally  around  the  radius, 
but  not  so  completely  as  the  supinator  brevis.  Its  insertion  may  take 
place  opposite  any  point  in  the  middle  third  of  the  bone. 

Relations. — It  is  covered  by  the  fascia  of  the  forearm,  by  the  su- 
pinator longus  and  extensor  carpi  radialis,  and  by  the  radial  artery 
and  musculo-spiral  nerve  :  it  covers  the  brachialis  anticus  and  flexor 
sublimis,  the  median  nerve  by  which  it  is  first  perforated,  and  the 
ulnar  artery. 

Action. — The  greater  the  amount  of  supination  of  the  forearm,  the 
more  effectual  is  the  action  of  this  muscle  as  a  pronator,  because 
then  it  is  much  more  completely  rolled  around  the  radius.  I  may 
remark  that,  on  account  of  its  obliquity,  it  is  inserted  into  the  radius 
at  an  angle  of  45"  ;  and  that,  consequently,  the  direction  in  which  it 
operates  is  rather  favourable.  It  acts  with  greater  advantage  in  pro- 
portion as  it  is  mserted  nearer  to  the  upper  end  of  the  radius  ;  and,  for  this  reason,  it» 

Ii 


250  MYOLOGY. 

power  must  vary  considerably  in  different  individuals.  When  pronation  is  carried  asj 
as  possible,  the  muscle  then  becomes  a  flexor  of  the  forearm.  After  the  preceding  i 
amination  of  this  muscle,  we  need  no  longer  be  surprised  at  the  great  energy  of  the  mo^ 
ment  of  pronation,  which  is  much  more  powerful  than  that  of  supination  ;  nor  yet  that 
is  the  most  natural  position  of  the  forearm,  for  the  pronator  teres  can  more  than  coui 
teract  the  two  supinators  taken  together.  In  fracture  of  the  bones  of  the  forearm,  tb. 
muscle  tends  to  obliterate  the  interosseous  space. 

The  Flexor  Carpi  Radialis. 

Dissection. — It  is  sufficient  to  divide  and  dissect  off  the  anterior  part  of  the  fsiscia  o! 
the  forearm,  in  order  to  expose  this  muscle,  which  may  be  recognised  by  the  followinj 
description : 

The  flexor  carpi  radialis  (radialis  intemus,  Albinus,  I,  fig.  118)  is  situated  immediatelj 
within  the  pronator  teres,  occupying  the  superficial  layer  of  the  anterior  aspect  of  tht 
forearm,  and  being,  as  far  as  its  tendon  is  concerned,  the  most  superficial  of  all  these 
muscles.  It  arises  from  the  lower  part  of  the  internal  border  and  from  the  inner  con- 
dyle of  the  humerus  {b,fig.  119),  and  is  inserted  {h')  into  the  second  metacarpal  bone. 
Its  origin  consists  of  a  tendon  common  to  it  and  to  the  pronator  quadratus,  palmaris 
longus,  flexor  sublimis,  and  flexor  carpi  ulnaris.  The  fleshy  fibres  immediately  arise 
from  within  a  sort  of  pyramidal  aponeurosis  given  off  by  this  common  tendon,  and  from 
the  body  of  the  muscle,  at  first  slender,  then  increasing  in  size,  and  again  tapering  to- 
wards its  attachment  to  the  two  surfaces  and  edges  of  a  tendon,  which  forms  the  lower 
two  thirds  of  the  muscle,  and  passes  obliquely  outward  and  downward  to  the  level  of  the 
OS  scaphoides  ;  it  there  penetrates  into  a  groove  formed  by  the  scaphoid  and  the  trape 
zium,  is  reflected  inward  along  this  oblique  groove,  and  terminates  upon  the  second  met- 
acarpal bone,  spreading  out  so  as  to  embrace  its  upper  extremity  ;  it  also  gives  off  a  ten- 
dinous expansion  to  the  trapezium,  and  sometimes  one  to  the  third  metacarpal  bone. 

Relations. — It  is  covered  by  the  fascia  and  the  skin,  through  which  it  is  very  clearly  de- 
fined :  it  is  in  relation  behind  with  the  flexor  sublimis  ;  on  the  outside,  with  the  tendon 
of  the  flexor  pollicis,  over  which  it  passes  at  an  acute  angle,  so  as  to  bind  it  down  ;  and 
lower  down,  with  the  wrist-joint.  A  very  strong  tendinous  sheath,  concealed  by  the  ab- 
ductor brevis  and  opponens  pollicis,  completes  the  groove  formed  by  the  scaphoid  and 
trapezium  for  its  tendon,  the  movements  of  which  are  facilitated  by  a  well-marked  sy- 
novial membrane.*  Its  most  important  relation  is  that  of  the  external  border  of  its  ten- 
don with  the  radial  artery.  The  superficial  position  of  the  tendon  prevents  our  feeling 
the  artery  when  the  muscle  is  contracted. 

Action. — It  flexes  the  second  row  of  the  carpus  upon  the  first,  and  this,  again,  upon  the 
forearm.  Moreover,  on  account  of  its  reflection,  it  is  a  pronator,  and,  according  to 
Winslow,  it  is  a  more  powerful  supinator  than  the  supinator  longus.  Its  obliquity  down- 
ward and  outward  explains  why  it  inclines  the  hand  to  the  radial  border  of  the  forearm, 
and  thus  acts  as  an  abductor. 

The  Palmaris  Longus. 

Although  this  small  muscle  is  rather  a  tensor  of  the  palmar  fascia  than  a  flexor  of  the 
hand,  I  have  yet  judged  it  proper  to  describe  it  in  this  place,  in  connexion  with  the  flexor 
carpi  radialis,  which,  in  contradistinction  to  this  muscle  {le  petit  palmaire),  has  also  been 
called  le  grand  palmaire  {Bichat).  It  is  a  small  fusiform,  slender,  fleshy  bundle  {c,fig. 
118),  of  about  four  inches  in  length,  arising  {c,fig.  119)  from  the  inner  condyle  of  the 
humerus  to  the  inner  side  of  the  preceding  muscle,  and  from  a  small  tendinous  cone, 
which  isolates  it  from  that  muscle,  the  flexor  sublimis,  and  the  flexor  carpi  ulnaris.  The 
fleshy  fibres  terminate  around  a  flat  tendon,  which  constitutes  the  lower  two  thirds  of 
the  muscle  (whence  the  name  palmaris  longus),  proceeds  vertically  downward  and  a  little 
outward,  and  terminates  by  expanding  in  front  of  the  anterior  annular  ligament  {g,  figs. 
118,  119)  of  the  wrist,  and  becoming  continuous  with  the  middle  palmar  fascia  (c',  fig.  118). 

This  muscle  is  subject  to  a  great  many  varieties,  and  is  often  wanting ;  its  fleshy  belly 
is  sometimes  very  long,  and  occasionally  occupies  the  middle  of  the  muscle. 

Relations. — The  same  as  those  of  the  preceding  muscle  {flexor  carpi  radialis) ;  its  ten- 
don is  very  superficial.  It  is  separated  from  the  neighbouring  muscles  by  a  very  strong 
sheath. 

Action. — It  is  a  tensor  of  the  palmar  fascia.  When  this  effect  has  been  produced,  it 
flexes  the  hand  upon  the  forearm.  According  to  Winslow,  it  would  assist  the  flexor 
carpi  radialis  in  pronation. 

The  Flexor  Carpi  Ulnaris. 

Dissection  — Remove  the  superficial  layer  of  the  fascia  covering  the  inside  of  the  'ire- 
arm,  taking  care,  in  dissecting  this  as  well  as  the  other  muscles  of  the  forearm,  to  stop 
at  the  points  where  that  fascia  adheres  intimately  to  the  fleshy  fibres. 

*  See  note,  p.  296. 


THE    FLEXOR    SUBLIMIS    DIGITORUM. 


251 


This  is  the  most  deep-seated  of  all  the  muscles  of  the  superficial  layer  of  the  forearm 
(ulnaris  internus,  Alhinus ;  cubital  interne,  Winslow,  d,figs.  118,  119,  121,  122). 

It  arises  from  the  inner  condyle  of  the  humerus  and  from  the  inner  edge  of  the  ole- 
cranon, these  two  origins  forming  an  arch  under  which  the  ulnar  nerve  passes.  It  also 
arises  sometimes,  though  slightly,  from  the  coronoid  process  of  the  ulna,  from  the  upper 
half  of  the  posterior  border  of  the  ulna,  through  the  medium  of  the  fascia  of  the  forearm, 
and  from  the  septum  between  itself  and  the  flexor  sublimis.  It  is  inserted  into  the  pisi- 
form bone.  The  origin  from  the  ridge  on  the  ulna  is  remarkable  ;  it  consists,  indeed,  of 
the  fascia  of  the  forearm,  which  becomes  thickened  and  divided  into  two  layers,  one 
deep  and  very  thin,  the  other  superficial  and  very  thick ;  in  the  interval  between  these 
the  fleshy  fibres  arise.  These  fibres  are  attached  to  the  surfaces  and  edges  of  a  very  strong 
tendon,  which  then  appears  upon  the  anterior  border  of  the  muscle,  and  continues  to  re- 
ceive the  fleshy  fibres  on  its  posterior  edge  until  its  insertion  into  the  pisiform  bone. 
This  takes  place  upon  the  anterior  surface  of  the  bone,  like  those  of  the  triceps  muscles 
of  the  arm  and  thigh  into  the  olecranon  and  pateUa.  The  tendon  then  becomes  continu- 
ous with  the  inferior  vertical  ligament  of  the  articulation  between  the  pisiform  and  cunei- 
form bones,  so  that  the  muscle  may,  in  fact,  be  regarded  as  inserted  into  the  fifth  meta- 
carpal bone. 

Relations. — It  is  covered  by  the  fascia,  and  is  intimately  united  with  it  for  a  consider- 
able extent :  it  covers  the  ulnar  artery  and  nerve,  the  flexor  sublimis,  the  flexor  profun- 
dus, and  the  pronator  quadratus.  The  most  important  of  all  its  relations  is  that  with  the 
ulnar  artery,  which  is  at  first  under  it,  and  then  lies  along  the  external  edge  of  its  ten- 
don, which  protects  the  artery,  and  serves  as  a  guide  in  the  application  of  a  ligature  to  it. 
I  have,  therefore,  been  in  the  habit  of  calling  this  muscle  the  satellite  of  the  ulnar  artery. 
Action. — This  muscle  acts  as  if  it  were  inserted  into  the  upper  extremity  of  the  fifth 
metacarpal  bone.  Were  it  not  for  the  peculiar  mode  of  its  attachment  to  the  pisiform 
bone,  it  would  have  been  inserted  parallel  to  its  lever  ;  whereas  it  is  really  inserted  at 
an  angle  of  about  45°.  It  flexes  the  second  row  of  the  carpus  upon  the  first,  and  this 
upon  the  forearm  ;  at  the  same  time  it  inchnes  the  hand  towards  its  ulnar  side.  Its  vio- 
mentum,  as  well  as  that  of  the  preceding  muscle,  occurs  during  semi-flexion  of  the  hand 
upon  the  forearm. 

The  Flexor  Sublimis  Digitorum. 

Dissection. — ^The  portion  of  this  muscle,  situated  in  the  forearm,  is  exposed  by  cutting 
across  the  middle,  and  turning  aside  the  pronator  teres,  the  flexor  carpi  radialis,  and  the 
pahnaris  longus,  which  form  a  superficial  layer  in  front  of  it.  With  a  little  care,  the  ori- 
gin of  this  muscle  may  be  separated  as  far  as  the  inner  condyle  of  the  humerus.  In  re- 
moving the  pronator  teres,  it  is  necessary  to  be  extremely  careful  to  avoid  dividing  the 
radial  origin  of  the  flexor  sublimis,  which  forms  a  very  thin  prolongation  under  the  pro- 
nator. The  dissection  of  the  palmar  and  digital  portions  of  the  mus- 
cle is  the  same  as  that  of  the  flexor  profundus. 

Divide  the  anterior  annular  ligament  of  the  carpus  vertically,  and 
remove  the  palmar  fascia ;  examine  the  disposition  of  this  structure 
opposite  the  heads  of  the  metacarpal  bones,  and  also  the  relations 
of  the  tendons  of  the  flexor  sublimis  and  flexor  profundus  in  the 
palm  of  the  hand  ;  then  dissect  the  digital  sheaths,  which  must  be 
divided  in  order  to  display  the  singular  manner  in  which  the  ten- 
dons of  the  flexor  sublimis  bifurcate  and  turn  round,  so  as  to  em- 
brace the  corresponding  tendons  of  the  flexor  profundus. 

The  flexor  superficialis,  sublimis,  ox  perforatus  (e  e,fig.  118  ;  e,jig. 
119),  is  a  broad,  flat,  thick  muscle,  divided  into  four  portions  below. 
It  arises  from  the  internal  condyle  or  epitrochlea  of  the  humerus, 
and  from  the  ulnar  and  radius,  and  is  inserted  into  the  second  pha- 
langes of  the  fingers.  It  arises  from  the  epitrochlea  by  the  common 
tendon,  from  a  rough  surface  on  the  fore  part  of  the  inner  side  of 
the  coronoid  process  of  the  ulna,  and  also  from  about  two  inches 
of  the  radius.  This  latter  origin  consists  of  tendinous  fibres  attach- 
ed to  that  obUque  portion  of  the  anterior  border  of  the  bone  which 
extends  inward  towards  the  bicipital  tuberosity,  and  from  which 
arise  the  supinator  brevis  above,  the  flexor  longus  pollicis  below, 
and  the  muscle  we  are  now  describing  in  the  middle.  A  great 
number  of  fibres  also  arise  from  the  broad  aponeurotic  septa  which 
divide  this  muscle  from  the  flexor  carpi  ulnaris,  and  from  the  other 
muscles  of  the  superficial  layer,  viz.,  the  pronator  teres,  the  flexor 
carpi  radialis,  and  the  palmaris  longus. 

From  these  diflferent  origins  the  fleshy  fibres  proceed  vertically 
downward,  forming  a  broad  and  thick  belly,  which  is  almost  imme- 
diately divided  into  four  portions.  These  at  first  are  in  juxtaposi- 
tion, but  soon  become  arranged  in  two  layers,  like  the  tendons  of 


Fig.  119. 


252 


MYOLOGY. 


the  extensor  communis,  viz.,  one  anterior  and  larger,  consisting  of  the  divisions  for  the 
median  and  ring  fingers  (the  latter  not  being  so  strong  as  the  former),  and  another  pos- 
terior, formed  by  the  divisions  for  the  index  and  little  finger.  Each  division  is,  indeed, 
a  small  muscle,  having  its  own  particular  tendon,  around  which  the  fleshy  fibres  are  ar- 
ranged, at  first  regularly,  and  afterward  on  one  side  only :  they  are  thus  semi-penniform 
muscles.  The  two  posterior  divisions  are  not  so  distinct  as  the  anterior,  and  have  a  pe- 
culiar arrangement :  they  generally  constitute  two  small  digastric  muscles ;  that  is  to 
say,  a  fleshy  belly  terminates  upon  a  flat  tendon,  which,  becoming  enlarged,  gives  origin, 
in  its  turn,  to  a  new  fleshy  belly.  The  four  tendons,  after  emerging  from  the  fleshy  fibres, 
pass  together  under  the  annular  ligament  {g)  of  the  carpus,  in  conjunction  with  the  me- 
dian nerve,  which  lies  on  their  outer  side,  and  is  often  mistaken  for  a  tendon,  and  with 
the  tendons  of  the  flexor  profundus  digitorum  and  the  flexor  longus  pollicis.  This  thick 
bundle  of  tendons  having  reached  the  palm  of  the  hand,  is  then  distributed  in  a  manner 
to  be  noticed  after  the  description  of  the  flexor  profundus,  with  the  tendons  of  which 
those  of  the  flexor  sublimis  are  intimately  connected. 

Relations. — It  is  covered  by  the  pronator  teres,  the  flexor  carpi  radialis,  the  palmaris 
longus,  the  flexor  carpi  ulnaris,  and  the  fascia  of  the  forearm ;  and  it  covers  the  flexor 
profundus  digitorum,  from  which  it  is  separated  by  the  ulnar  vessels  and  nerves  ;  it  also 
covers  the  median  nerve  and  the  flexor  longus  pollicis,  to- which  it  generally  sends  a 
tendinous  and  fleshy  prolongation. 

The  Flexor  Profundus  Digitorum. 

Dissection. — This  muscle  is  exposed  by  cutting  across  the  flexor  sublimis  and  the  flex- 
or carpi  ulnaris. 
The  flexor  profundus  or  perforans  (i,  fl.gs.  119, 120)  is  situated  under  the  superficial  flex- 
Fig.  120.  °^'  which  it  exceeds  in  size,  but  resembles  it  in  being  divided  below 

into  four  portions. 

Attachments. — It  arises  from  the  upper  three  fourths  of  the  internal 
and  anterior  surfaces  of  the  ulna,  from  a  well-marked  cavity  situated 
on  the  inner  side  of  the  coronoid  process  behind  the  rough  eminence 
which  gives  attachment  to  the  internal  lateral  ligament  of  the  elbow, 
from  the  inner  two  thirds  of  the  interosseous  ligament,  from  that  part 
of  the  fascia  of  the  forearm  which  covers  the  inner  surface  of  the  ulna, 
and,  lastly,  by  a  few  fibres,  from  within  and  below  the  bicipital  tuber- 
osity of  the  radius.  It  is  inserted  into  the  front  of  the  bases  of  the  last 
phalanges  of  the  fingers  ii,figs.  119,  120). 

The  fleshy  fibres  arise  directly  from  these  numerous  origins,  and 
proceed  vertically  downward,  the  internal  fibres  alone  being  directed 
somewhat  obliquely  forward  and  outward.  The  belly  of  the  muscle 
thus  formed  continues  to  increase  in  size,  and  is  then  divided  into  four 
unequal  portions,  each  constituting  a  semi-penniform  muscle.  These 
four  small  muscles  are  in  juxtaposition,  and  terminate  in  as  many  flat 
tendons,  which  occupy  the  lower  two  thirds  of  the  anterior  surface  of 
the  entire  muscle,  and  are  remarkable  for  being  divided  into  very  reg- 
ular and  closely-united  parallel  bands  of  a  nearly  white  colour.  The 
four  tendons  emerging  from  the  fleshy  fibres  at  various  heights,  but 
always  above  the  anterior  annular  ligament  of  the  carpus,  pass  under 
this  ligament  conjointly  with  the  tendons  of  the  flexor  sublimis,  the 
flexor  pollicis  longus,  and  the  median  nerve.  In  this  situation  they 
are  placed  behind  the  tendons  of  the  flexor  sublimis,  which  are  ar- 
ranged in  two  layers,  as  we  have  already  seen.  The  tendons  of  the 
flexor  profundus  are  always  in  juxtaposition,  and,  moreover,  are  united 
together  by  means  of  dense  cellular  tissue  and  tendinous  bands  pass- 
ing from  one  to  the  other :  the  fasciculus  for  the  index  finger  alone  remains  distinct ; 
and,  therefore,  the  flexion  of  this  finger  is  almost  as  independent  of  that  of  the  others  as 
its  extension,  for  which  latter  movement  it  receives  a  special  muscle.  Immediately  below 
the  annular  ligament  the  tendons  separate  from  each  other ;  the  two  anterior  tendons 
of  the  flexor  sublimis  no  longer  cover  the  two  posterior,  but  all  four  become  situated  in 
front  of  the  corresponding  tendons  of  the  flexor  profundus,  and  arrive  together  at  the 
metacarpo-phalangal  articulations  :  here  they  are  received,  at  first,  into  a  very  strong 
fibrous  sheath,  resulting  from  the  division  of  the  palmar  fascia,  and  afterward  into  an- 
other sheath  {s,figs.  118,  119),  which  converts  the  groove  in  front  of  the  phalanges  into 
a  canal.  If  we  divide  any  of  these  digital  sheaths,  we  find  the  tendon  of  the  superficial 
flexor  becoming  flattened  and  hollowed  underneath,  as  it  were,  into  a  groove,  which  is 
exactly  moulded  upon  the  tendon  of  the  deep  flexor.  About  the  middle  of  the  first  pha- 
lanx the  tendon  of  the  sublimis  ie,fl.g.  119)  bifurcates,  and  gives  passage  to  that  of  the 
profundus,  which  it  embraces  by  turning  round  it  like  the  thread  of  a  screw,  and  be- 
coming posterior  instead  of  anterior,  as  it  was  before.  The  two  halves  of  the  tendon 
then  reunite  to  form  a  groove  having  its  concavity  directed  forward,  and  again  separate 


THE   LUMBEICALES    AND    THE    FLEXOR    LONGUS    POLLICIS.  '253 

to  be  inserted  into  the  rough  edge  of  the  groove  on  the  second  phalanx.  The  tendon  of 
the  flexor  profundus  (i'  i',  figs.  119,  120),  on  the  contrary,  passes  directly  through  the 
sheath  formed  by  that  of  the  flexor  sublimis,  and  is  inserted  into  the  third  phalanx.  The 
tendons  of  the  flexor  profundus,  moreover,  present  in  their  whole  course  very  slightly 
apparent  traces  of  division.  From  the  relation  of  the  tendons  of  the  two  flexors  to  each 
other,  the  superficial  muscle  has  been  called  the  perforatus,  and  the  deep  one  the  perforans. 

Relations. — These  should  be  examined  in  the  forearm,  in  the  palm  of  the  hand,  and 
along  the  fingers. 

In  the  forearm  the  flexor  profundus  is  covered  by  the  flexor  sublimis,  from  which  it  is 
separated  by  an  incomplete  tendinous  septum,  and  by  the  median  nerve.  It  covers  the 
ulna,  the  interosseous  ligament,  and  the  pronator  quadratus ;  it  corresponds  within  to 
the  flexor  carpi  ulnaris,  and  without  to  the  flexor  longus  pollicis.  The  ulnar  vessels 
and  nerves  are  at  first  situated  between  this  muscle  and  the  flexor  sublimis,  and  after- 
ward separate  it  from  the  flexor  carpi  ulnaris. 

In  the  palm  its  tendons  are  subjacent  to  those  of  the  flexor  sublimis,  and  cov^r  the 
interosseous  muscles  and  the  adductor  pollicis.  The  lumbricales  muscles  take  their 
origin  from  them. 

Along  the  fingers  its  tendons  are  in  relation  behind  with  the  grooves  of  the  phalanges, 
and  with  the  metacarpo-phalangal  and  phalangal  articulations,  and  in  front  with  the 
tendons  of  the  sublimis  and  the  fibrous  sheaths  of  the  fingers.  < 

Action  of  the  two  Flexors. — These  muscles  flex  the  third  phalanx  upon  the  second,  the 
second  on  the  first,  this,  again,  upon  the  corresponding  metacarpal  bone,  and,  lastly,  the 
hand  upon  the  forearm.  The  flexor  sublimis  has  no  action  upon  the  third  phalanges. 
Its  origin  from  the  internal  condyle  of  the  humerus  enables  it  to  act  upon  the  forearm, 
and  to  assist  in  flexing  it  upon  the  arm.  It  is  scarcely  necessary  to  say  that  the  bifur- 
cation of  the  tendons  of  the  flexor  sublimis  is  intended  to  afford  a  sheath  to,  and  bind 
down,  those  of  the  flexor  profundus.  The  flexor  profundus  flexes  the  third  phalanx  upon 
the  second,  the  second  upon  the  first,  the  first  upon  the  corresponding  metacarpal  bone, 
and,  lastly,  the  hand  upon  the  forearm. 

The  Lumbricales. 

The  lumbricales  (x,figs.  119,  120)  are  small  fleshy  tongues,  which  may  be  regarded  as 
accessories  of  the  flexor  profundus.  They  are  four  in  number,  distinguished  as  the  first, 
second,  &c.,  counting  from  without  inward.  They  extend  from  the  tendons  of  the  flexor 
profundus  to  the  first  phalanges  of  three  or  four  fingers.  They  arise  from  the  tendons 
after  these  have  passed  through  the  annular  ligament :  the  first  and  the  second  in  front 
of  the  tendons  for  the  index  and  middle  fingers,  the  third  in  the  interval  between  those 
for  the  middle  and  ring  fingers,  and  the  fourth  in  the  interval  between  those  for  the  ring 
and  little  fingers.  From  these  origins  they  proceed,  those  near  the  median  hue  verti- 
cally, and  those  at  either  side  obliquely  downward  to  the  outer  side  of  the  metacarpo- 
phalangal  articulations  of  the  corresponding  fingers,  where  they  terminate  by  a  broad 
tendinous  expansion  inserted  into  the  edges  of  the  extensor  tendons,  and  completing  the 
sheath  which  those  tendons  form  on  the  back  of  the  first  phalanges.  The  tendon  of  the 
third  lumbricalis  appears  to  me  to  be  almost  always  inserted,  not  into  the  outer  side  of 
the  ring  finger,  but  into  the  inner  side  of  the  middle  finger :  an  arrangement  that  cannot 
well  be  accounted  for.  It  is  not  uncommon  to  find  this  third  lumbricalis  bifurcated,  and 
attached,  not  only  to  the  inner  side  of  the  middle,  but  to  the  outer  side  of  the  ring  finger. 

Relations. — They  are  placed  between  and  upon  the  tendons  of  the  flexor  profundus, 
and  have,  therefore,  the  same  relations  as  those  tendons  in  the  palm  of  the  hand ;  they 
are  also  in  relation  with  the  sides  of  the  metacarpo-phalangal  articulations,  and  the  ten- 
dons of  the  interosseous  muscles. 

Action. — It  is  difficult  to  determine  their  actions  precisely.  Vesalius  has  described 
them  as  adductors,  and  Spigelius  as  flexors.  I  agree  with  Riolanus  in  regarding  them 
as  specially  intended  to  keep  the  extensor  tendons  closely  applied  to  the  phalanges,  and 
to  serve  instead  of  a  proper  sheath.  They  are  of  use  also  in  binding  together  the  ex- 
tensor and  flexor  tendons,  and  preventing  the  displacement  of  either. 

The  Flexor  Longus  Pollicis. 

Dissection. — ^The  same  as  that  of  the  flexor  profundus. 

The  flexor  longus  pollicis  {I,  figs.  119,  120)  is  situated  upon  the  same  plane  as  the  flex 
or  profundus  digitorum,  of  which  it  may  be  considered  a  division  ;  it  is  thick,  elongated, 
and  penniform. 

Attachments. — It  arises  from  the  upper  three  fourths  of  the  radius,  from  the  contiguous 
portion  of  the  interosseous  ligament,  from  the  anterior  border  of  the  radius,  and  not  un- 
frequently  by  a  prolongation,  tendinous  at  its  extremities  and  fleshy  in  the  middle,  from 
the  flexor  sublimis  digitorum.  It  is  inserted  into  the  upper  end  of  the  second  phalanx 
of  the  thumb.  The  fleshy  fibres  arise  directly  from  these  origins,  pass  vertically  down- 
ward, and  are  attached  to  the  posterior  surface  of  a  flat  tendon,  which  forms  a  continu- 
ation of  the  series  of  tendons  of  the  flexor  profundus  on  the  outside,  and,  like  them,  is 


254  MYOLOGY. 

divided  into  bands.  The  fleshy  fibres  accompany  the  tendon  as  far  as  the  anterior  an- 
nular hgament  of  the  carpus  ;  it  then  passes  beneath  this  ligament,  is  reflected  over  the 
inside  of  the  trapezium,  and  proceeds  obhquely  outward  along  the  first  metacarpal  bone. 
When  it  reaches  the  metacarpo-phalangal  articulation  of  the  thumb,  it  is  received  in  an 
osteo-fibrous  sheath,  resembling  in  every  respect  that  of  the  tendons  of  the  other  fingers, 
and,  like  them,  is  inserted  in  front  of  the  upper  extremity  of  the  ungual  phalanx  of  its 
corresponding  finger  (Z,  ^g-.  120). 

Relations. — It  is  covered  by  the  flexor  sublimis,  the  flexor  carpi  radialis,  the  supinator 
longus,  and  the  radial  artery  ;  it  covers  the  radius  and  the  interosseous  ligament,  from 
which  it  is  separated  above  by  the  interosseous  vessels  and  nerves,  and  below  by  the 
pronator  quadratus.  Its  tendon  is  the  most  external  of  those  which  pass  under  the  an- 
terior annular  ligament  of  the  carpus,  after  leaving  which  it  is  received  into  a  deep  mus- 
cular groove  formed  by  the  muscles  of  the  ball  of  the  thumb,  and  is  ultimately  enclosed 
in  its  own  osteo-fibrous  sheath. 

Action. — It  flexes  the  last  phalanx  of  the  thumb  upon  the  first,  this  upon  the  first  met- 
acarpal bone,  and  then  the  hand  upon  the  forearm.  In  order  to  understand  its  action 
precisely,  we  must  suppose  the  muscular  force  to  be  concentrated  upon  the  upper  end  of 
the  reflected  portion ;  it  is  then  easy  to  see  that  it  draws  the  phalanges  inward,  while 
flexing  them.    It  is,  therefore,  an  opponens  muscle. 

The  Pronator  Quadratus. 

Dissection. — Cut  across  all  the  tendons  occupying  the  lower  part  of  the  anterior  region 
of  the  forearm,  and  this  muscle  will  be  exposed. 

This  small  muscle  (le  petit  pronateur,  Bichat,  m,figs.  119,  120)  is  situated  at  the  low- 
er part  of  the  anterior  region  of  the  forearm,  and  forms  the  deepest  layer  of  this  region. 
It  is  regularly  quadrilateral,  and  thicker  than  at  first  sight  it  appears  to  be. 

Attachments. — It  arises  firom  the  lower  fourth  of  the  internal  border  of  the  ulna,  which 
is  directed  so  decidedly  backward  inferiorly,  that  the  muscle  is  rolled  round  the  bone ; 
also,  from  an  aponeurotic  layer  much  thicker  below  than  above,  directed  obliquely  up- 
ward and  outward,  and  occupying  the  inner  third  of  the  muscle,  upon  which  it  terminates 
in  a  number  of  elegant  intersections ;  lastly,  from  all  that  portion  of  the  anterior  surface 
of  the  ulna  upon  which  it  lies.  From  these  origins  the  fibres  proceed  horizontally  out- 
ward (le  pronateur  transverse,  Winslow),  becoming  longer  as  they  are  more  superficial,  to 
the  lower  fourth  of  the  external  border,  anterior  surface,  and  internal  border  of  the  radius. 

Relations. — It  is  covered  by  the  flexor  profundus  digitorum,  the  flexor  longus  poUicis, 
the  flexor  carpi  radialis,  and  the  radial  and  ulnar  arteries,  and  it  partially  covers  the  two 
bones  of  the  forearm  and  the  interosseous  ligament. 

Action. — ^The  pronator  quadratus  tends  to  approximate  the  two  bones  of  the  forearm  ; 
but  as  it  is  rolled  around  the  ulna,  which  is  immovable,  it  causes  the  radius  to  turn  upon 
that  bone,  and  is  therefore  a  pronator.  Its  action  is  much  more  energetic  than  would 
at  first  sight  appear :  this  depends  on  the  number  of  its  fleshy  fibres,  which  are  arranged 
in  several  layers,  the  most  superficial  being  the  longest. 

The  Muscles  of  the  External  Region  of  the  Forearm. 
The  muscles  of  this  region  are,  the  supinator  longus,  the  extensores  carpi  radiales, 
longior  and  brevior,  and  the  supinator  brevis. 

The  Supinator  Longus. 

Dissection. — The  brachial  portion  of  this  muscle  is  exposed  in  the  dissection  of  the 
brachialis  anticus  and  the  triceps,  and  the  portion  situated  in  the  forearm,  by  removing 
the  fascia  from  the  outer  and  anterior  aspect  of  the  muscles  of  this  region. 

The  'supinator  longus  (/,  Jigs.  118,  121),  which  is  the  most  superficial  muscle  of  the  ex- 
ternal and  anterior  aspect  of  the  forearm,  belongs  both  to  the  arm  and  the  forearm  (bra- 
chio-radialis,  Soemmering),  and  constitutes,  in  a  great  measure,  the  oblique  ridge  forming 
the  external  boundary  of  the  bend  of  the  elbow.  It  is  a  long,  flat  muscle,  fleshy  in  its 
upper  two  thirds,  and  tendinous  in  its  lower  third. 

Attachments. — It  arises  from  the  outer  border  of  the  humerus,  and  from  the  external 
inter-muscular  septum  of  the  arm ;  the  extent  of  its  humeral  attachment  varies  from  the 
lower  fourth  to  the  lower  third  of  that  bone,  and  is  limited  above  by  the  groove  for  the 
musculo-spiral  nerve.  It  is  inserted  into  the  base  of  the  styloid  process  of  the  radius. 
The  fleshy  fibres  proceed  from  their  origins  downward,  forward,  and  a  little  inward,  to 
form  a  fleshy  belly,  which  is  flattened  from  without  inward,  and  is  applied  to  the  brachi- 
alis anticus.  After  reaching  the  lower  end  of  the  humerus,  the  fleshy  belly  becomes 
flattened  from  before  backward,  and  passes  vertically  downward.  At  first  it  is  thick,  but, 
during  its  progress,  it  expands,  and  becomes  thin,  until  its  fibres  terminate  successively 
upon  the  anterior  surface  of  an  aponeurosis,  which  becomes  entirely  free  from  fleshy 
fibres  above  the  middle  of  the  forearm,  and  is  gradually  contracted  into  a  flat  tendon, 
that  is  inserted  into  the  styloid  process  of  the  radius. 

Relations. — It  is  covered  bv  the  fascise  of  the  arm  and  forearm  :  in  the  arm  it  is  en- 


THE    EXTENSORES    CARPI    EADIALES,    LONGIOR    ET    BREVIOR.  255 

closed  in  the  same  sheath  with  the  brachialis  anticus,  from  which  it  is  separated  by  the 
radial  or  musculo-spiral  nerve  ;  in  the  forearm  it  has  a  sheath  proper  to  itself:  it  is  in 
relation  with  the  brachialis  anticus,  which  is  at  first  within,  and  afterward  behind  it ; 
then  with  the  extensor  carpi  radialis  longior,  the  tendon  of  the  biceps,  the  supinator  bre- 
vis,  the  pronator  teres,  the  flexor  carpi  radialis,  the  flexor  digitorum  sublimis,  the  flexor 
longus  pollicis,  the  radial  artery  and  veins,  and  the  radial  nerve.  Its  inner  border  limits 
the  bend  of  the  elbow  on  the  outside  :  the  radial  artery  emerges  from  beneath  this  bor- 
der, and  then  lies  parallel  to  it.  Its  outer  border  is  separated  from  the  extensor  carpi 
radialis  longior  by  cellular  tissue,  and,  inferiorly,  is  in  contact  with  the  dorsal  branch  of 
the  radial  nerve,  which,  at  first,  was  situated  beneath  it.  The  most  important  of  all 
these  relations  is  that  with  the  radial  artery,  of  which  the  long  supinator  may  be  consid- 
ered the  satellite  muscle,  and  might  be  designated  the  muscle  of  the  radial  artery. 

Action. — It  might  be  asked,  Why  does  the  supinator  longus  form  an  exception  to  the 
general  rule,  in  being  inserted  into  the  lower  end  of  the  lever  which  it  is  intended  to 
move  1  for,  while  the  forearm  is  in  a  state  of  supination,  the  axis  of  the  muscle  is  verti- 
cal, and  its  action  appears  limited  to  that  of  flexing  the  forearm  ;  but  if  the  limb  be  pro- 
nated,  the  direction  of  the  muscle  becomes  oblique  from  without  inward,  and,  therefore, 
supination  is  the  result  of  its  contraction.  After  this  effect  has  been  produced,  if  the 
muscle  still  continues  to  act,  the  forearm  is  flexed  upon  the  arm.  It  is  needless  to  state 
that  the  distance  of  its  insertion  from  the  fulcrum  gives  the  muscle  great  power,  not- 
withstanding its  disadvantageous  angle  of  incidence. 

The  Extensor  Carpi  Radialis  Longior. 

Dissection. — This  muscle,  as  well  as  the  succeeding  one,  will  be  exposed  at  the  same 
time  as  the  supinator  longus,  beneath  which  it  is  placed.  The  lower  end  of  its  tendon 
occupies  the  dorsum  of  the  wrist,  and  should  also  be  exposed. 

The  extensor  carpi  radialis  longior  (le  premier  ou  long  radial  exteme  ;  radiahs  externus 
longior,  Albinus,  n,figs.  119,  121)  is  situated  on  the  external  and  posterior  aspect  of  the 
forearm,  below  the  supinator  longus,  of  which  it  seems  to  be  a  continuation  at  its  origin 
from  the  humerus  :  like  that  muscle,  it  is  flattened  from  within  outward  in  the  arm,  and 
from  before  backward  in  the  forearm  :  it  is  fleshy  in  its  upper  third,  and  tendinous  in  its 
lower  two  thirds. 

Attachments. — It  arises  from  the  rough  triangular  impression  terminating  the  external 
border  of  the  humerus,  from  the  external  inter-muscular  septum,  and  from  the  anterior 
surface  of  the  common  tendon.  It  is  inserted  into  the  back  of  the  upper  end  of  the  sec- 
ond metacarpal  bone.  The  fleshy  fibres  arising  directly  from  the  parts  mentioned  con- 
stitute a  bundle,  at  first  flattened  on  the  sides,  and  forming  a  continuation  of  the  supina- 
tor longus,  from  which  it  is  often  difficult  to  separate  it :  it  afterward  becomes  flattened 
from  before  backward.  The  fibres  pass  vertically  downward,  and  are  attached  to  the 
anterior  surface  of  a  tendon,  a  little  beyond  the  upper  third  of  the  forearm.  The  tendon 
then  becomes  narrower  and  thicker,  proceeds  along  the  outer  border  of  the  radius,  pass- 
es under  the  tendons  of  the  abductor  longus  and  extensor  brevis  pollicis,  which  cross  it 
obliquely,  and  turns  a  little  outward,  and  then  backward,  to  arrive  at  a  groove  common 
to  it  and  the  extensor  carpi  radialis  brevier ;  it  is  then  crossed  at  an  acute  angle  by  the 
tendon  of  the  extensor  longus  pollicis,  and  is  finally  inserted,  by  an  expanded  termina- 
tion, into  the  second  metacarpal  bone  {n',fig.  121). 

Relations. — It  is  covered  by  the  supinator  longus  and  the  fascia  of  the  forearm  ;  on  the 
outside  of  the  forearm,  it  is  covered  and  crossed  obliquely  by  the  abductor  longus  and  ex- 
tensor brevis  pollicis.  and  in  the  wrist  by  the  tendon  of  the  extensor  longus  pollicis.  It 
covers  the  elbow-joint,  the  extensor  carpi  radialis  brevier,  and  the  back  of  the  wrist-joint. 

The  Extensor  Carpi  Radialis  Brevior, 
The  extensor  carpi  radialis  brevior  (le  second  ou  court  radial  exteme  ;  radialis  externus 
brevior,  Albinus,  o,figs.  119,  121,  122)  is  thicker,  but  shorter,  than  the  preceding,  below 
which  it  is  placed.  It  arises  from  the  external  condyle  or  epicondyle  of  the  humerus,  by 
a  tendon  common  to  it  and  the  extensor  muscles  of  the  fingers  ;  also,  from  a  very  strong 
aponeurosis,  situated  upon  its  posterior  surface ;  and  from  another  tendinous  septum, 
which  divides  it  from  the  extensor  communis  digitorum.  It  is  inserted  into  the  back  part 
of  the  upper  end  of  the  third  metacarpal  bone.  The  fleshy  fibres,  thus  arising  from  the 
external  condyle  by  means  of  an  aponeurotic  pyramid,  are  attached  to  the  posterior  sur- 
face of  a  tendon,  which  becomes  gradually  narrower  and  thicker  as  it  receives  them. 
The  fibres  themselves  terminate  about  the  middle  of  the  forearm,  and  then  the  flat  ten- 
don passes  backward  into  the  same  groove  on  the  radius  as  that  of  the  last-named  mus- 
cle, the  two  tendons  being  retained  in  it  by  the  same  fibrous  sheath,  and  lubricated  by 
tne  same  synovial  membranes,  but  separated  from  each  other  by  a  small  vertical  ridge 
of  bone.  After  leaving  the  common  sheath,  the  tendon  of  the  short  separates  from  that 
of  the  long  radial  extensor,  passes  still  more  posteriorly,  and  is  inserted  into  the  third 
metacarpal  bone  (o',  Tf^s.  121,  122). 

RelatioDis. — It  is  covered  by  the  preceding  muscle,  and,  like  it,  is  crossed  obliquely  on 


256  MYOLOGY. 

the  outside  by  the  long  abductor,  the  short,  and  then  the  long  extensor  muscles  of  the 
thumb  :  it  covers  the  external  surface  of  the  radius,  from  which  it  is  separated  by  the 
supinator  brevis  above,  and  the  pronator  teres  in  the  middle.  Its  tendon  covers  and 
protects  the  back  of  the  wrist.  In  consequence  of  the  different  length  of  their  fleshy 
fibres,  the  supinator  longus  and  the  two  radial  extensors  of  the  carpus  are  arranged  one 
above  the  other,  the  highest  being  the  supinator  longus,  and  the  lowest  the  extensor 
carpi  radialis  brevior. 

Action  of  the  two  Radial  Extensors. — These  two  muscles,  which,  from  their  insertions 
might  be  called  the  posterior  radials,  extend  the  second  row  of  the  carpus  upon  the  firs 
and  this  upon  the  forearm  ;  they  are  also  abductors  of  the  hand,  for  they  incline  it  to- 
wards the  radial  side  of  the  forearm.     The  extensor  carpi  radialis  longior  being  attach- 
ed to  the  humerus,  can  assist  in  flexing  the  forearm. 

The  Supinator  Brevis. 

Dissection. — Pronate  the  forearm  forcibly.  In  order  to  expose  this  muscle  completely, 
divide  the  two  radial  extensors  of  the  carpus,  and  even  some  of  the  muscles  of  the  su- 
perficial layer,  on  the  back  of  the  forearm. 

The  supinator  brevis  (p,figs.  119, 120,  122)  is  a  broad  muscle  curved  into  the  form  of  a 
hollow  cylinder,  and  rolled  round  the  upper  third  of  the  radius  :  it  forms  by  itself  the  deep 
layer  of  the  external  region  of  the  forearm. 

Attachments. — It  arises  from  the  external  lateral  Ugament  of  the  elbow,  with  which  it 
is  blended,  and  by  this  means  from  the  external  condyle  ;  from  the  annular  ligament  of 
the  radius ;  from  the  external  border  of  the  ulna,  which  is  provided  with  a  projecting 
ridge  for  this  purpose  ;  from  a  deep  triangular  excavation,  in  front  of  this  ridge,  arid  below 
the  lesser  sigmoid  cavity  of  the  ulna ;  and,  lastly,  from  the  deep  surface  of  an  expansion  of 
its  tendon  of  origin  and  the  external  lateral  ligament,  which  covers  the  greater  part  of 
the  muscle.  From  these  different  origins  {fig.  122)  the  fleshy  fibres  pass  round  the  ra- 
dius, into  the  posterior,  external,  and  anterior  surfaces  of  which  bone  they  are  inserted, 
embracing  in  front  the  bicipital  tubercle  and  the  tendon  of  the  biceps  {figs.  119,  120).  I 
have  seen  a  fleshy  prolongation  of  this  muscle,  covering  the  anterior  half  of  the  annular 
ligament  of  the  radius,  of  which  it  might  be  regarded  an  extensor. 

Relations. — The  supinator  brevis  is  covered  by  the  radial  extensors,  the  supinator  lon- 
gus, the  pronator  teres,  the  extensor  communis  digitorum,  the  extensor  digiti  minimi, 
the  extensor  carpi  ulnaris,  the  anconeus,  and  the  radial  artery  and  vein :  it  covers  the 
upper  third  of  the  radius,  and  also  its  annular  ligament,  the  elbow-joint,  and  the  inter- 
osseous ligament.  It  is  perforated  by  the  deep  branch  of  the  radial  nerve,  which  is  dis- 
tributed to  all  the  muscles  on  the  back  of  the  forearm. 

Action. — No  muscle  in  the  body  is  so  completely  rolled  around  the  lever  that  it  is  in- 
tended to  move,  for  it  forms  five  sixths  of  a  cylinder ;  it  is,  therefore,  the  chief  agent  in 
supination,  and  the  supinator  longus  can  only  be  regarded  as  an  accessory. 

Muscles  of  the  Posterior  Region  of  the  Forearm. 
The  muscles  of  the  posterior  region  of  the  forearm  constitute  two  very  distinct  layers : 
one  superficial,  comprising  the  extensor  communis  digitorum,  the  extensor  digiti  minimi, 
and  the  extensor  carpi  ulnaris  ;  the  other  deep,  comprising  the  abductor  pollicis  longus,  the 
extensor  brevis  and  extensor  longus  pollicis,  and  the  extensor  indicis 

Muscles  of  the  Superficial  Layer. 

One  mode  of  dissection  is  common  to  all  these  muscles.  Make  a  circular  mcision 
through  the  skin  at  the  lower  part  of  the  arm ;  pronate  the  arm,  arifl  make  a  perpendic- 
ular incision  from  the  external  condyle  of  the  humerus  to  the  third  metacarpal  bone, 
entirely  dividing  the  sub-cutaneous  cellular  tissue  down  to  the  fascia ;  remove  this  fascia 
by  careful  dissection,  except  where  it  is  very  adherent.  Trace  the  tendons  of  the  ex- 
tensor muscles  along  the  back  of  the  fingers. 

The  Extensor  Communis  Digitorum. 
The  extensor  communis  digitorum  {b,fig.  121),  situated  at  the  back  of  the  forearm,  sim- 
ple above  and  divided  into  four  portions  below,  arises  from  the  external  condyle  of  the 
humerus,  and  is  inserted  into  the  second  and  third  phalanges  of  the  four  fingers.  Its  ori- 
gin consists  of  a  tendon  common  to  it,  and  to  the  extensor  carpi  radialis  brevior,  exten- 
sor digiti  minimi,  and  extensor  carpi  ulnaris.  This  tendon  consists  of  a  four-sided  pjrra- 
raid,  and  is  formed  by  the  fascia  of  the  forearm,  by  a  lamina  separating  this  muscle  from 
the  extensor  carpi  radialis  longior,  by  another  lamina  separating  it  from  the  extensor 
digiti  minimi  and  the  extensor  carpi  ulnaris,  and,  lastly,  by  another  situated  between  it 
and  the  supinator  brevis.  The  fleshy  fibres  arising  from  the  interior  of  this  pyramid  form 
at  first  a  thin,  but  afterward  a  much  larger  muscle,  which  becomes  flattened  from  before 
backward,  and  soon  divides  into  four  fasciculi.  The  two  middle  fasciculi,  intended  for 
the  middle  and  the  ring  fingers,  are  stronger  than  those  destined  for  the  index  and  little 
fingers,  i.  e.,  the  two  extreme  fasciculi,  which,  lower  down,  become  placed  in  front  of 


THE    EXTENSOR   DIGITI    MINIMI. 


257 


the  middle  fasciculi.     In  this  manner  they  all  pass  under  the  dor-  Fig.  191. 

sal  ligament  (r,fig.  121)  of  the  carpus  in  a  proper  sheath.  After 
leaving  this  sheath,  in  which  they  are  provided  with  a  synovial 
capsule,*  extending  both  above  and  below  the  dorsal  ligament,  the 
four  tendons  become  situated  on  the  same  plane,  and  diverge  from 
each  other ;  the  two  middle  tendons  proceed  along  the  backs  of  the 
corresponding  metacarpal  bones ;  the  external  and  internal  ten- 
dons {b'  h',Jig.  121)  correspond  to  the  interosseous  spaces,  which 
they  cross  obliquely,  in  order  to  assume  a  position  behind  the  heads 
of  the  metacarpal  bones,  to  which  they  belong.  Having  reached 
the  metacarpo-phalangal  articulations,  the  tendons  become  nar- 
rower and  thickened,  and  give  oif  on  each  side  a  fibrous  expansion, 
attached  to  the  sides  of  the  joint ;  they  then  enlarge  again  so  as  to 
cover  the  dorsal  surface  of  the  first  phalanges,  receive  and  are  re- 
enforced  by  the  tendons  of  the  lumbricales,  and  opposite  the  ar- 
ticulation of  the  first  with  the  second  phalanx,  they  divide  into 
three  portions,  one  median,  which  is  implanted  upon  the  upper  end 
of  the  second  phalanx,  and  two  lateral,  which  pass  2dong  the  sides 
of  the  second  phalanx,  approach  each  other  at  the  lower  half  of  the 
dorsal  surface  of  the  second  phalanx,  unite  by  their  neighbouring 
edges,  and  are  inserted  into  the  upper  end  of  the  third  phalanx. 
Opposite  the  metacarpal  bones  they  sometimes  split  into  two  or 
three  small  juxtaposed  tendons,  and  at  the  lower  end  of  these 
bones  the  tendons  for  the  little,  ring,  and  middle  fingers  commu- 
nicate with  each  other  by  expansions  of  variable  size,  and  some- 
times by  a  true  bifurcation  (see  fig.  121).  The  tendon  for  the  in- 
dex finger  is  alone  free.  The  communication  of  the  tendon  of  the 
little  with  that  of  the  ring  finger  takes  place  opposite  the  metacar- 
po-phalangal articulation,  by  means  of  a  transverse  band,  which 
forms  a  projection  under  the  skin.  Lastly,  we  not  unconmionly 
see  a  tendinous  prolongation  arising  from  the  anterior  surface  of  these  tendons,  and  in- 
serted into  the  upper  end  of  the  first  phalanx. 

Relations. — The  extensor  communis  digitorum  is  covered  by  the  fascia  of  the  forearm, 
from  which  a  great  number  of  its  fibres  arise  superiorly,  by  the  dorsal  ligament  of  the 
carpus  and  the  dorsal  fascia  of  the  metacarpus,  which  separate  it  from  the  skin  :  it  cov- 
ers the  supinator  brevis,  the  three  long  muscles  of  the  thumb,  the  extensor  proprius  in- 
dicis,  the  lower  radio-cubital  articulation,  the  carpus,  the  metacarpus,  and  the  fingers. 

Action. — ^This  muscle  extends  the  third  phalanx  upon  the  second,  the  second  upon  the 
first,  the  first  upon  the  corresponding  metcarpal  bone,  then  the  carpus,  and,  lastly,  the 
radio-cubital  articulation.  It  is  necessary  for  me  to  mention  the  independence  of  the 
muscular  fasciculi  proceeding  to  each  finger  :  this  is  peculiar  to  man,  and  is  much  more 
remarkable  in  some  individuals  than  in  others.  By  continual  exercise,  the  faculty  of 
extending  one  finger  without  the  others  may  be  acquired.  The  tendon  for  the  index  is 
generally  the  only  one  not  united  to  the  others,  and  therefore  the  movements  of  this 
finger  are  by  far  the  most  independent. 

The  Extensor  Digiti  Minimi. 

This  is  a  very  slender  muscle  (extensor  proprius  auricularis,  Albinus,  c,  fig.  121)  placed 
on  the  inner  side  of  the  common  extensor,  to  which  it  appears  to  be  an  appendix.  It  is 
difficult  to  trace  its  origin  as  far  as  the  common  tendon,  with  which  it  is  connected  only 
by  an  aponeurotic  prolongation.  Its  fleshy  fibres  arise  from  this  prolongation,  and  from 
a  fibrous  pyramid  which  separates  it  from  the  muscles  of  the  deep  layer,  from  the  exten- 
sor communis  digitorum  externally,  and  internally  from  the  extensor  carpi  ulnaris,  and 
is  completed  superficially  by  the  fascia  of  the  forearm.  The  fibres  constitute  a  small, 
fusiform,  fleshy  belly,  which  accompanies  the  tendon  (at  least  on  one  side)  as  far  as  the 
head  of  the  ulna ;  there  the  tendon  enters  a  special  fibrous  sheath  formed  behind  the 
head  of  that  bone ;  it  is  then  reflected  inward  to  the  fifth  metacarpal  bone,  behind  which 
it  is  retained  in  a  thinner  sheath,  which,  like  the  preceding,  is  lined  by  a  synovial  mem- 
brane.t  The  tendon  then  spUts  into  two  bands,  of  which  the  external  (or  radial)  re- 
ceives the  inner  bifurcation  of  the  extensor  communis.  The  three  tendinous  prolonga- 
tions becoming  united,  envelop,  as  in  a  sheath,  the  dorsal  aspect  of  the  first  phalanx  of 
this  finger ;  having  reached  the  articulation  of  the  first  with  the  second  phalanx,  they 
divide  into  three  portions,  which  are  attached  precisely  in  the  same  manner  as  the  ten- 
dons of  the  extensor  communis. 

Action. — As  its  name  indicates,  this  muscle  extends  the  little  finger.  It  might  at  first 
sight  be  imagined  that  this  finger  might  be  moved  independently,  since  it  receives  a  sep- 
arate muscle  ;  but  the  connexion  of  its  tendon  with  that  of  the  extensor  communis  ren- 


See  note,  p.  296. 


Kk 


t  See  note,  p.  296. 


t,58  MYOLOGY. 

ders  any  such  independent  action  as  difficult  as  in  the  other  fingers,  and  much  more  so 
than  in  the  index  finger. 

The  Extensor  Carpi  Ulnaris. 

The  extensor  carpi  ulnaris  (c,  fig.  121),  the  most  superficial  and  the  most  internal*  of  the 
muscles  on  the  back  of  the  forearm,  arises  from  the  external  tuberosity  of  the  humerus ; 
from  the  posterior  surface  of  the  ulna,  which  is  a  little  excavated  for  this  purpose  ;  from 
the  middle  third  of  the  posterior  border  of  that  bone  ;  and  from  the  anterior  surface  of 
an  aponeurosis  covering  the  muscle  behind.  It  is  inserted  behind  the  upper  end  of  the 
fifth  metacarpal  bone.  Its  origin  is  effected  by  means  of  a  fibrous  pyramid,  the  apex  of 
which  is  attached  to  the  outer  tuberosity  of  the  humerus.  From  the  interior  of  this  pyr- 
amid, and  from  the  other  origins  above  mentioned,  the  fleshy  fibres  proceed  to  a  tendon, 
which,  by  a  very  uncommon  arrangement,  extends  through  the  substance  of  the  muscle, 
even  from  its  superior  attachment,  without  commencing  in  the  form  of  an  aponeurosis. 
At  the  lower  third  of  the  forearm,  this  tendon  appears  on  the  posterior  border  of  the  then 
semi-penniform  muscle,  and  continues  to  receive  fleshy  fibres  on  its  anterior  edge  until 
it  enters  the  groove  intended  for  it  on  the  ulna.  This  oblique  groove  is  continued  as  far 
Fig.  182.  as  the  insertion  of  the  tendon  into  the  metacarpal  bone,  by  means  of  a 

long,  fibrous  sheath,  and  is  lined  throughout  by  a  synovial  membrane. 
Relations. — The  extensor  carpi  ulnaris  is  covered  by  the  fascia  of 
the  forearm :  it  covers  the  ulna,  the  supinator  brevis,  and  the  mus- 
cles of  the  deep  layer. 

Action. — It  extends  the  second  row  of  the  carpus  upon  the  first,  and 
this  upon  the  forearm.     It  is,  at  the  same  time,  an  adductor  of  the 
_g       hand,  which  it  inclines  towards  the  ulnar  border  of  the  forearm. 

The  Anconeus. 

The  anconeus  (brevis  anconeus,  Eustachius ;  le  petit  ancone,  Wins- 
low,  ff,  figs.  121,  122)  is  a  short,  triangular  muscle,  so  named  from 
its  situation  {uyKuv,  the  prominence  of  the  elbow).  It  appears  to  be 
a  continuation  of  the  external  portion  of  the  triceps,  from  which  it  is 
only  separated  by  a  very  slight  cellular  interval. 

Attachments. — It  arises  from  the  back  part  of  the  outer  tuberosity 
of  the  humerus,  and  is  inserted  into  the  outer  side  of  the  olecranon, 
and  a  triangular  surface  bounded  internally  by  the  posterior  border  of 
the  ulna.  Its  origin  from  the  condyle  consists  of  a  tendon  quite  dis- 
tinct from  that  common  to  the  muscles  on  the  back  part  of  the  fore- 
arm. This  tendon  splits  into  two  diverging  bands.  The  fleshy  fibres 
arising  from  these  proceed  inward,  the  upper  horizontally,  the  lower 
obliquely  downward,  and  are  inserted  directly  into  the  outer  side  of 
the  olecranon,  so  as  to  be  continuous  with  the  triceps,  and  into  the 
surface  of  the  ulna. 

Relations. — It  is  covered  by  a  prolongation  from  the  fascia  of  the 
triceps,  and  it  covers  the  radio-humeral  articulation,  the  annular  lig- 
ament of  the  radius,  the  ulna,  and  a  small  portion  of  the  supinator 
brevis. 

Action. — ^It  extends  the  forearm  upon  the  arm,  and  vice  versa ;  from  its  oblique  direc- 
tion, it  can  also  rotate  it  inward. 

Muscles  of  the  Deep  Layer. 
Dissection. — This  is  the  same  for  all  the  muscles  of  the  deep  layer  of  the  forearm,  and 
consists  in  removing  the  muscles  of  the  superficial  layer,  especially  the  extensor  com- 
munis digitorum  and  the  extensor  digiti  minimi. 

The  Mductor  Longus  Pollicis. 

The  abductor  longus  pollicis  (extensor  ossis  metacarpi  pollicis,  i,figs.  121,  122)  is  the 
broadest,  thickest,  and  most  external  muscle  of  the  deep  layer  (le  grand  abducteur,  Bichat). 

Attachments. — It  arises  from  the  ulna  below  the  origin  of  the  supinator  brevis,  from 
the  interosseous  hgament,  from  the  radius,  and  from  a  tendinous  septum  between  it  and 
the  extensor  longus  pollicis.  It  is  inserted  into  the  upper  end  of  the  first  metacarpal 
bone.  From  the  above-mentioned  origins  the  fleshy  fibres  proceed  obUquely  downward 
and  outward,  constitute  a  flattened  fusiform  belly,  and  are  successively  attached  to  the 
posterior  surface  of  an  aponeurosis,  which  becomes  condensed  into  a  flat  tendon ;  this 
tendon  turns  round  the  radius,  crossing  over  the  radial  extensors  of  the  carpus,  and,  at 
the  same  time,  ceasing  to  receive  any  fleshy  fibres  ;  it  is  then  received  into  the  outer 
groove  on  the  lower  end  of  the  radius,  conjointly  with  the  tendon  of  the  extensor  brevis 

*  It  is  needless  to  remark  that  this  internal  situation  presupposes  the  supination  of  the  forearm.  In  prona- 
tion, this  muscle  may  be  correctly  termed  ulnaris  externus,  and  le  cubital  externe,  according  to  Albinus  and 
Witulow. 


THE   EXTENSOR   BREVIS    POLMCIS,  ETC.  254 

pollicis,  a  small  fibrous  septum  intervening  between  them,  and,  finally,  is  inserted  into 
the  first  metacarpal  bone.  This  tendon  is  almost  always  divided  longitudinally  into  two 
equal  parts,  and  not  unfrequently  the  division  extends  up  to  the  fleshy  portion.  Of  these 
two  divisions,  one  is  inserted  into  the  first  metacarpal  bone,  the  other  furnishes  attach- 
ments to  the  abductor  brevis  pollicis. 

Relations. — It  is  covered  by  the  extensor  communis  digitorum  and  extensor  digiti  min- 
imi :  it  lies  immediately  under  the  fascia,  from  the  outer  side  of  the  radius  to  its  termi- 
nation. It  covers  the  interosseous  ligament,  the  radius,  the  tendons  of  the  radial  exten- 
sors of  the  carpus,  and  the  outer  side  of  the  wrist-joint,  where  it  may  be  easily  distin- 
guished under  the  skin. 

Action. — It  extends  and  abducts  the  first  metacarpal  bone :  for  a  long  time  it  was 
called  the  extensor  of  the  thumb ;  but  its  chief  use  is,  as  Albinus  first  remarked,  in  ab- 
duction. Winslow  observes  that,  from  its  obliquity,  it  can  act  as  a  supinator ;  lastly,  it 
assists  in  extending  the  hand. 

The  Extensor  Brevis  Pollicis. 

This  muscle  (extensor  primi  intemodii  pollicis,  I,  figs.  121,  122)  is  situated  internally 
to  the  preceding,  which  it  exactly  resembles-  in  figure  and  direction,  and  with  which  it 
was  for  a  long  time  confounded  (partie  du  premier  extenseur  du  pouce,  Winslow).  It  is, 
however,  shorter  and  mpre  slender  (petit  extenseur  du  pouce,  Bichat). 

It  arises  from  the  radius,  occasionally  from  the  ulna,  and  from  the  interosseous  liga- 
ment ;  and  is  inserted  into  the  upper  end  of  the  first  phalanx  of  the  thumb.  Its  origin 
consists  of  short,  tendinous  fibres,  the  fleshy  fibres  proceeding  from  which  constitute  a 
slender  fasciculus,  having  a  similar  arrangement  to  that  of  the  preceding  muscle ;  its 
tendon  is  received  into  the  same  fibrous  sheath,  but  is  divided  from  the  other  by  a  small 
septum,  and  passes  on,  to  be  inserted  into  the  first  phalanx. 

Relations. — The  same  as  those  of  the  abductor  longus. 

Action. — It  extends  the  first  phalanx  upon  the  first  metacarpzil  bone,  and  then  becomes 
an  abductor  and  extensor  of  the  metacarpal  bone  of  the  thumb. 

The  Extensor  Longus  Pollicis. 

This  muscle  (extensor  secundi  internodii  pollicis,  m,figs.  121, 122)  is  much  larger  than 
the  extensor  brevis,  within  and  parallel  to  which  it  is  situated.  It  arises  from  a  consid- 
erable extent  of  the  ulna,  from  the  interosseous  ligament,  and  from  the  tendinous  septa, 
dividing  it  from  the  extensor  carpi  ulnaris,  and  the  extensor  proprius  indicis  :  it  is  insert- 
ed into  the  upper  end  of  the  second  phalanx  of  the  thumb.  The  fleshy  fibres  form  a  flat 
fusiform  bundle,  directed  obliquely  like  the  preceding  muscle  ;  they  terminate  in  succes- 
sion around  a  tendon,  which  emerges  from  them  at  the  carpal  extremity  of  the  ulna,  en- 
ters a  special  osteo-fibrous  sheath,  and  crosses  obliquely  over  the  tendons  of  the  two  ra- 
dial extensors,  being  separated  from  the  tendons  of  the  abductor  longus  and  extensor 
brevis  pollicis  by  an  intervjil  which  may  be  readily  distinguished  through  the  integu- 
ments, and  gives  rise  to  the  hollow  on  the  outer  side  of  the  wrist,  commonly  called  the 
salt-cellar.  The  tendon  next  crosses  obliquely  over  the  first  interosseous  space,  gains  the 
inner  edge  of  the  first  metacarpal  bone,  and  then  that  of  the  first  phalanx,  upon  which  it  is 
expanded,  and  proceeds  to  be  inserted  into  the  second  or  ungual  phalanx  of  the  thumb. 

Relations. — Its  general  relations  are  the  same  as  those  of  the  preceding  muscle. 

Action. — Its  uses  are  also  the  same ;  but  it  acts  in  a  special  manner  upon  the  second 
phalanx  of  the  thumb,  which  it  extends  upon  the  first  before  exerting  any  influence  upon 
this  last-mentioned  bone.    It  has  less  power  in  abduction  than  the  preceding  muscles. 

The  Extensor  Proprius  Indicis. 

This  is  an  elongated  fusiform  muscle  (indicator,  Albinus,  r,  fig.  122)  like  the  preceding, 
below  and  parallel  to  which  it  is  situated.  It  arises  from  the  ulna,  the  interosseous  liga 
ment,  and  a  septum  intervening  between  it  and  the  extensor  longus  pollicis  :  it  is  insert- 
ed into  the  last  two  phalanges  of  the  index  finger.  The  fleshy  fibres  proceed  obliquely 
from  their  origins  and  terminate  around  a  tendon,  which  they  accompany  as  far  as  the 
sheath  of  the  extensor  communis  digitorum :  into  this  sheath  the  tendOn  enters,  and. 
having  escaped  from  it,  crosses  obliquely  over  the  carpus  and  the  second  interosseous 
space,  becomes  situated  on  the  inside  of  the  tendon  given  off  to  the  index  finger  by  the 
extensor  conununis,  unites  intimately  with  that  tendon  opposite  the  lower  end  of  the 
metacarpus,  and  terminates  with  it  in  the  manner  already  indicated.  Its  relations  are 
the  same  as  those  of  the  preceding  muscles. 

Action. — It  enables  the  index  finger  to  be  extended  independently  of  the  others,  and 
hence,  without  doubt,  arises  the  particular  use  of  that  finger.  I  should  add,  that  the  union 
of  its  tendon  with  the  one  furnished  by  the  common  extensor  is  so  intimate,  that  its  in- 
dependence of  action  would  have  been  much  less,  had  not  the  fleshy  fasciculus  of  the 
common  extensor  destined  for  it  been  itself  almost  isolated. 


260  MYOLOGY. 


MUSCLES  OF  THE  HAND. 

Tlie  AbdiMor  Brevis  Pollicis. — Opponejis  Pollicis. — Flexor  Brevis  Pollicis. — Adductor  Pol- 
lids. — Palmaris  Brevis. — Abductor  Digiti  Minimi. — Flexor  Brevis  Digiti  Minimi. — Op- 
ponens  Digiti  Minimi. — The  Interosseous  Muscles,  Dorsal  and  Palmar. 

The  muscles  of  the  hand  occupy  the  entire  palmar  region.  They  are  divided  into 
those  situated  on  the  outer  side,  viz.,  the  muscles  of  the  thenar  eminence,  or  ball  of  the 
thumb ;  those  on  the  inner  side,  viz.,  the  muscles  of  the  hypothenar  eminence,  or  of  the 
little  finger ;  and  those  which  occupy  the  interosseous  spaces. 

All  the  muscles  of  the  thenar  eminence  belong  to  the  thumb  ;  they  are,  in  the  order 
of  their  superposition,  the  abductor  brevis,  the  opponens,  the  flexor  brevis,  and  the  ad- 
ductor pollicis.  Those  of  the  hypothenar  eminence  all  belong  to  the  little  finger,  and 
are  the  abductor,  the  flexor  brevis,  and  the  opponens.  The  palmaris  brevis  may  be  in- 
cluded in  this  region. 

The  interosseous  muscles  are  seven  in  number — four  dorsal  and  three  palmar.  The 
lumbricales,  vi^hich  belong  to  this  region,  have  been  already  described  with  the  tendons 
of  the  flexors  of  the  fingers. 

Muscles  of  the  Thenar  Eminence,  or  Muscles  belonging  to  the  Thumb 

I  divide  these  into  three  muscles  inserted  into  the  outer  side  of  the  first  phalanx  of 
the  thumb,  or  into  the  first  metacarpal  bone,  and  a  single  muscle  inserted  into  the  inner 
side.  The  former  are  the  abductor  brevis,  the  opponens,  and  the  flexor  brevis  ;  the  lat- 
ter consists  of  the  adductor,  in  which  I  include  a  part  of  the  flexor  brevis  of  authors 
generally. 

Muscles  inserted  into  the  Outer  Side  of  the  First  Phalanx  of  the  Thumb,  or 
into  the  First  Metacarpal  Bone. 

Dissection. — Make  an  oblique  incision  from  the  middle  of  the  annular  ligament  of  the 
carpus  to  the  outer  side  of  the  first  phalanx  of  the  thumb,  and  a  circular  incision  round 
the  wrist ;  detach  the  flaps,  raise  the  external  and  middle  palmar  fasciae,  and  then  cau- 
tiously separate  the  muscles  of  this  region,  which  are  recognised  by  the  following  char- 
acters. 

The  Abductor  Brevis  Pollicis. 

This  is  the  most  superficial  of  the  muscles  constituting  the  ball  of  the  thumb  {q,  fig. 
119).  It  arises  by  tendinous  and  fleshy  fibres  from  the  os  scaphoides,  from  the  upper, 
anterior,  and  external  part  of  the  anterior  annular  ligament  of  the  carpus,  and  almost 
always  from  an  expansion  of  the  tendon  of  the  abductor  longus  pollicis.  It  is  a  small, 
•hin,  flat  muscle,  passing  outward  and  downward,  and  inserted  by  a  flat  tendon  into  the 
outer  side  of  the  first  phalanx  of  the  thumb.  A  very  narrow  cellular  line  separates  it  on 
the  inside  from  the  flexor  brevis,  which  is  situated  on  the  same  plane.  It  is  covered  by 
the  external  palmar  fascia,  and  it  covers  the  opponens  muscle,  from  which  it  is  distin- 
guished by  the  direction  of  its  fibres,  and  by  a  thin  intervening  aponeurosis. 

Action. — It  draws  the  thumb  forward  and  inward,  and  therefore  might  be  termed  the 
superficial  opponens.    From  its  attachments,  it  might  be  called  scaphoido-phalangal. 

The  Opponens  Pollicis. 

The  opponens  pollicis  (r,  figs.  119, 120),  a  small  triangular  muscle,  arises  from  the  trape- 
zium, and  the  anterior  and  external  part  of  the  anterior  annular  ligament  of  the  carpus, 
in  front  of  the  sheath  of  the  flexor  carpi  radialis.  From  these  origins,  which  are  partly 
fleshy  and  partly  tendinous,  the  fleshy  fibres  radiate  downward  and  outward,  the  highest 
being  the  shortest  and  the  most  horizontal.  They  are  inserted  into  the  entire  length  of 
the  outer  border  of  the  first  metacarpal  bone. 

This  muscle  is  covered  by  the  abductor  brevis,  which  projects  a  little  beyond  it  on  the 
outside,  and  from  which  it  is  separated  by  a  more  or  less  distinct  aponeurosis.  It  cov- 
ers the  first  metacarpal  bone,  and  its  articulation  with  the  trapezium. 

Action. — It  draws  the  first  metacarpal  bone  inward  and  forward,  thus  opposing  it  to  the 
others,  as  its  name  indicates.    From  its  attachments,  it  may  be  called  trapezio-metacarpal. 

The  Flexor  Brevis  Pollicis. 
It  is  difficult  to  point  out  the  limits  of  this  muscle,  or,  rather,  they  have  hitherto  been 
quite  arbitrary.  Its  inferior  attachment  has  been  usually  divided  between  the  external 
and  the  internal  sesamoid  bones  (Boyer,  Traitl  d' Anatomic,  torn,  ii.,  p.  307 ;  Bichat,  Ana- 
tomic Descriptive,  torn,  ii.,  p.  272) ;  but  we  shall  consider  that  portion  only  whioli  is  at- 
tached to  the  external  sesamoid  bone  as  belonging  to  this  muscle,  referring  tlie  entire 
fleshy  mass  that  is  inserted  into  the  internal  sesamoid  bone  to  the  adductor  pollicis.* 

'  The  arrangement  I  have  adopted  is  founded  upon  the  inferior  attachments  of  the  musr les,  for  at  their 
origins  they  are  so  blended  that  their  division  is  more  or  less  arbitrary.  I  divide  the  muscular  fasciculi  con- 
nected witu  the  thumb,  therefore,  into  two  sets,  viz.,  those  proceeding  from  the  carpus  to  tlie  first  metacan>al 


THE   ADDUCTOR   P0LLICI8,  ETC.  26^1 

This  division  is,  moreover,  established  by  the  tendon  (I,  fig.  120)  of  the  flexor  longns 
pollicis.  Proceeding  then  from  below  upward,  in  the  dissection  of  the  flexor  brevis  {t. 
iigs.  119,  120),  we  shall  see  that  it  is  triangular,  much  larger  than  the  preceding  two 
muscles,  bifid  above,  and  channelled  in  front.  It  arises  by  tendinous  and  fleshy  fibres 
from  a  process  on  the  trapezium,  from  the  lower  edge  of  the  annular  ligament,  from  all 
the  reflected  portion  of  that  ligament  forming  the  sheath  of  the  flexor  carpi  radialis,  and 
extending  as  far  as  the  os  magnum,  and  from  the  os  magnum  itself  by  a  portion  which 
is  usually  distinct.  From  these  different  origins  the  fleshy  fibres  proceed  downward  and 
outward,  the  intem£d  being  the  most  oblique  ;  and,  converging  so  as  to  form  a  thick  fas- 
ciculus, are  inserted,  through  the  medium  of  the  external  sesamoid  bone,  into  the  first 
phalanx. 

Relations. — It  is  covered  by  the  external  pahnar  fascia,  which  is  prolonged  in  front  of  it : 
it  covers  the  tendon  of  the  flexor  longus  pollicis,  and  more  internally  those  of  the  common 
flexor.  It  also  covers  a  small  portion  of  the  outer  border  of  the  adductor  pollicis,  and 
the  tendon  of  the  flexor  carpi  radialis.  Its  outer  border,  or,  rather,  side,  is  in  relation 
with  the  short  abductor,  from  which  it  is  easily  separated,  and  with  the  opponens,  some- 
times being  continuous  with  it.  Its  inner  border  is  distinct  from  the  adductor  below, 
but  is  confounded  with  it  at  its  origin.  Its  tendon  of  insertion  into  the  phalanx  is  cov- 
ered by  that  of  the  short  abductor,  which  lies  externally  to  it.  From  its  attachments,  it 
might  be  called  trapezio-phalangal,  and,  from  its  uses  and  position,  the  opponens  internus. 

Action. — It  is  evidently  not  a  flexor  pollicis,  but,  like  the  preceding  muscles,  it  draws 
the  thumb  forward  and  inward,  and  it  acts  more  decidedly  in  producing  the  latter  effect. 
because  it  is  inserted  in  a  more  favourable  manner  than  the  other  muscles.  This,  there- 
fore, is  also  an  opponens  muscle. 

Muscle  inserted  into  the  Inner  Side  of  the  First  Phalanx  of  the  Thumb. 
The  Adductor  Pollicis. 

This  is  the  largest  of  all  the  muscles  of  the  thumb  (m,  figs.  119,  120) ;  it  is  very  ir- 
regularly triangular,  and  arises  from  the  entire  extent  of  the  anterior  border  of  the  third 
metacarpal  bone,  from  the  anterior  surface  of  the  os  magnum,  from  the  anterior  and  up- 
per part  of  the  trapezoides,  from  the  anterior  part  of  the  trapezium  by  a  tendinous  and 
fleshy  fasciculus,  and  from  the  palmar  interosseous  fascia,  near  the  third  metacarpal 
bone.  From  these  different  origins  the  fleshy  fibres  proceed,  the  lower  horizontally,  the 
rest  more  and  more  obliquely  outward ;  they  all  converge  to  form  a  thick  fleshy  bundle, 
which  is  inserted  through  the  medium  of  the  internal  sesamoid  bone  into  the  first  pha- 
lanx of  the  thumb. 

Relations. — Its  inner  two  thirds  are  deeply  situated,  and  covered  by  the  tendons  of  the 
flexor  profundus  digitorum,  by  the  lumhricales,  and  by  an  aponeurosis,  which,  becoming 
continuous  with  the  deep  interosseous  fascia,  constitutes  the  sheath  of  the  muscle.  It 
is  sub-cutaneous  near  its  lower  border.  It  covers  the  first  two  interosseous  spaces,  from 
which  it  is  separated  by  a  very  strong  aponeurosis.  It  is  again  sub-cutaneous  behind, 
also  along  its  lower  border,  which  may  be  easily  felt  under  the  fold  of  skin,  extending 
from  the  thimib  to  the  index  finger. 

Action. — It  is  an  adductor ;  it  draws  the  thumb  towards  the  median  line  or  axis  of  tho 
hand,  represented  by  the  third  metacarpal  bone. 

Muscles  of  the  Hypothenar  Eminence,  or  Muscles  belonging  to  the  Little  Finger. 

These  muscles  correspond  exactly  to  those  of  the  thumb :  the  reason  that  three  only 
are  described  is,  that  the  one  which  represents  the  adductor  of  the  thumb  is  situated  in 
the  fourth  interosseous  space,  and  is,  therefore,  classed  with  the  interosseous  muscles, 
to  be  hereafter  described.  All  the  muscles  of  the  hypothenar  eminence  are  inserted  into 
the  inner  side  of  the  first  phalairx  of  the  little  finger,  or  into  the  third  metacarpal  bone 
We  find  also  a  cutaneous  muscle  in  this  region,  viz.,  the  palmaris  brevis. 

The  Palmaris  Brevis. 

This  is  a  very  thin  square  muscle  (caro  quaedam  quadrata,  J,  fig.  1 18),  situated  in  the 
adipose  tissue  covering  the  hypothenar  eminence.  It  arises  from  the  anterior  annular 
ligament  of  the  carpus,  and  the  inner  edge  of  the  middle  palmar  fascia,  by  very  distinct 
tendinous  fasciculi,  succeeded  by  equally  distinct  fleshy  bundles,  which  pass  horizontally 
inward,  and  terminate  in  the  skin. 

Relations. — It  is  covered  by  the  skin,  to  which  it  adheres  intimately,  especially  by  its 
inner  extremity  (le  pahnaire  cutane,  Winslow ) ;  it  covers  the  muscles  of  the  hypothenar 

bone  and  to  the  outer  side  of  the  first  phalanx  of  the  thumb,  and  those  extending  from  the  carpus  to  the  inner 
side  of  the  same  phalanx.  The  first  set,  which  might  be  regarded  as  a  single  muscle,  comprises  the  abductor 
brevis,  the  opponens,  and  the  flexor  brevis ;  the  other  constitutes  the  abductor  pollicis,  which  I  regard  as  the 
first  palmar  interosseous  muscle.  The  action  of  the  first  set  is  common,  viz.,  to  carry  the  thumb  forward  and 
inward  ;  they  are,  therefore,  all  muscles  of  opposition  (perhaps  no  muscles  are  so  badly  named  as  those  of  the 
thenar  eminence) ;  the  muscle  formeJ  !jy  the  second  set  is  really  an  adductor,  as  its  name  implies,  and  so  are 
all  the  palmar  interossci.  ;im0Qg    .., a  :i  it  ^l  (Uld  be  included. 


262  MYOLOGY. 

eminence  and  the  ulnar  artery  and  nerve,  from  all  of  which  it  is  separated  by  the  inter- 
nal palmar  fascia. 
Action. — It  corrugates  the  skin  over  the  hypothenar  eminence. 

The  Abductor  Digiti  Minimi. 

It  arises  from  the  pisiform  bone,  and  from  an  expansion  of  the  flexor  carpi  ulnans, 
by  tendinous  fibres  ;  these  are  succeeded  by  a  fusiform  fleshy  belly  {v,fig.  119),  which 
passes  vertically  along  the  internal  (or  ulnar)  surface  of  the  fifth  metacarpal  bone,  and  is 
inserted  by  a  flat  tendon  into  the  inner  side  of  the  first  phalanx  of  the  little  finger. 

Relations. — It  is  covered  by  the  external  palmar  fascia,  and  covers  the  opponens  digiti 
minimi. 

Action. — As  it  name  denotes,  it  abducts  the  little  finger  from  the  axis  of  the  hand. 

The  Flexor  Brevis  Digiti  Minimi. 

This  muscle  {w,fig.  119)  is  situated  on  the  outer  or  radial  border  of  the  precedmg, 
from  which  it  is  distinguished  by  arising  from  the  unciform  bone.  ■  The  two  muscles  are 
separated  by  the  ulnar  vessels  and  nerves,  which  pass  between  them,  in  order  to  penetrate 
into  the  deep  palmar  region.  In  other  respects,  as  in  direction,  insertions,  and  relations, 
the  muscles  resemble  each  other ;  they  have  accordingly  been  described  by  Chaussier  as 
a  single  muscle,  under  the  name  of  Ze  carpo-phalangien  du  petit  doigt.  This  muscle  is  often 
wanting,  but  the  fleshy  fibres  which  usuaUy  constitute  it  are  then  always  found  in  some 
measure  blended  with  the  other  muscles. 

Action. — It  produces  slight  flexion  of  the  little  finger. 

The  Opponens  Digiti  Minimi. 

This  muscle  {y,fig.  119)  is  generally  distinct  from  the  preceding,  and  is  the  represent- 
ative of  the  opponens  pollicis.  It  arises  from  the  hooklike  process  of  the  unciform  bone, 
and  from  the  contiguous  part  of  the  annular  ligament :  from  these  points  the  fibres  pro- 
ceed downward  and  inward  (i.  e.,  towards  the  ulnar  border  of  the  hand),  the  highest  be- 
ing the  shortest  and  the  most  horizontal :  they  are  i-nserted  into  the  whole  length  of  the 
inner  or  ulnar  margin  of  the  fifth  metacarpal  bone. 

Relations. — It  is  covered  by  the  preceding  muscles  and  by  the  internal  palmar  fascia  : 
it  covers  the  fifth  metacarpal  bone,  the  corresponding  interosseous  muscle,  and  the  ten- 
don of  the  superficial  flexor  proceeding  to  the  little  finger. 

Action. — It  opposes  the  little  finger  to  the  thumb  by  drawing  it  forward  and  outward. 

The  Interosseous  Muscles. 

Dissection. — Remove  the  tendons  of  the  extensor  muscles  behind,  and  those  of  the  flexor 
muscles  in  front,  together  with  the  lumbricales,  preserving,  at  the  same  time,  the  digital 
inseiiions  of  these  small  muscles.  Dissect  and  study  the  deep  palmar  fascia,  a  fibrous 
layer  covering  the  interosseous  muscles  in  the  palm  of  the  hand,  which  sends  prolonga- 
tions between  the  two  kinds  of  these  muscles,  and  is  inserted  into  the  anterior  borders 
of  the  metacarpal  bones,  enclosing  each  interosseous  muscle  in  a  proper  sheath.  After 
having  studied  the  palmar  and  dorsal  fascia,  separate  the  bones  of  the  metacarpus  by 
tearing  their  connecting  ligaments,  and  the  interossei  will  then  be  completely  exposed. 

The  interossei,  so  named  from  their  position,  and  distmguished  from  each  other  by  the 
numerical  appellations  first,  second,  third,  &c.,  are  divided  into  palmar  (p  p  p,  Jig.  123) 
and  dorsal  {ddd  d),  according  as  they  are  situated  nearer  to  the  palm  or  to  the  back  of 
the  hand.     They  are  also  distinguished  into  adductors  and  abductors  of  the  fingers. 

There  are  two  in  each  interosseous  space,  one  occupying  its  dorsal,  the  other  its  pal- 
mar aspect ;  and,  as  there  are  four  interosseous  spaces,  it  would  seem  that  there  should 
be  eight  interosseous  muscles ;  nevertheless,  seven  only  are  admitted  by  modern  anat- 
omists, in  consequence  of  the  first  palmar  interosseous  muscle,  which  belongs  to  the 
thumb,  being  separately  described  as  the  adductor  pollicis.  This  separation  is  founded 
upon  the  peculiar  arrangement  presented  by  that  muscle,  which  is  not  attached  from  the 
first  to  the  second,  but  extends  from  the  first  to  the  third  metacarpal  bone  ;  an  importjuit 
fact,  that  explains  the  great  extent  to  which  the  thumb  can  be  adducted. 

A  minute  description  of  the  interosseous  muscles  would  be  both  useless  and  tedious. 
I  shall  content  myself  with  pointing  out  their  genereil  conformation,  and  the  law  which 
regulates  their  arrangement. 

In  taking  a  general  view  of  the  interosseous  muscles,  they  must  be  considered  with 
regard  to  the  adduction  or  abduction  of  the  fingers  ;  but  these  terms  must  not  be  under- 
stood in  reference  to  the  axis  of  the  skeleton,  but  to  the  axis  of  the  hand,  which  is  rep- 
resented by  a  line  passing  through  the  third  metacarpal  bone  and  the  middle  finger.  This 
being  admitted,  all  the  dorsal  interossei  will  be  found  to  be  abductors,  and  all  the  palmar 
interossei  adductors. 

Thus,  the  first  dorsal  interosseous  muscle  proceeds  from  the  first  and  second  meta- 
carpal bones  to  the  outer  or  radial  side  of  the  first  phalanx  of  the  index  finger  :  it  is  there- 
fore an  abductor  of  that  finger.    The  second  extends  ft-om  the  second  and  third  meta- 


THE   DORSAL   INTEROSSEI.  263 

carpal  bones  to  the  outer  or  radial  side  of  the  first  phalanx  of  the  middle  finger,  and  is  an 
abductor  of  that  finger.  The  third  extends  from  the  third  and  fourth  metacarpal  bones 
to  the  inner  or  ulnar  side  of  the  phalanx  of  the  middle  fingers,  and  is  also 
an  abductor  of  the  same,  because  it  separates  it  firom  the  supposed  axis  of 
the  hand.  The  fourth  extends  from  the  fourth  and  fifth  metacarpal  bones 
to  the  inner  or  ulnar  side  of  the  first  phalanx  of  the  fourth  finger,  and  it  again 
is  an  abductor  of  that  finger  from  the  axis  of  the  hand,  although,  as  well  as 
the  preceding  muscle,  it  is  an  adductor  as  regards  the  axis  of  the  body.  In 
order  to  render  this  view  more  intelligible,  I  have  been  accustomed  to  rep- 
resent the  five  fingers  by  five  lines  (see  diagram  d),  to  prolong  the  middle 
line  for  the  axis  of  the  hand,  and  then  to  draw  other  lines  (the  four  fine  lines) 
representing  the  axes  of  the  muscles ;  the  demonstration  is  thus  rendered 
complete. 

In  the  same  manner,  all  the  palmar  interossei  are  adductors  as  regards  the  axis  of  the 
hand.  Thus  the  first,  which  is  represented  by  the  adductor  pollicis,  and  extends  from 
the  third  metacarpal  bone  to  the  inner  or  ulnar  side  of  the  first  phalanx  of  the  thumb,  is 
an  adductor  as  regards  the  axis  of  the  hand  as  well  as  that  of  the  body ;  the  second,  ex- 
tending from  the  second  metacarpal  bone  to  the  inner  or  ulnar  side  of  the  first  phalanx 
of  the  index  finger,  is  an  adductor  both  as  regards  the  axis  of  the  hand  and  that  of  the 
body ;  the  third,  extending  from  the  fourth  metacarpal  bone  to  the  outer  or  radial  side 
of  the  first  phalanx  of  the  ring  finger,  is  an  adductor  as  regards  the  axis  of 
the  hand ;  and,  lastly,  the  fourth,  extending  from  the  fifth  metacarpal  bone  to 
the  outer  or  radial  side  of  the  first  phalanx  of  the  little  finger,  is  an  adductor 
as  regards  the  axis  of  the  hand,  but  an  abductor  in  reference  to  the  axis  of 
the  body.  A  similarly-constructed  figure,  as  that  employed  for  the  dorsal 
interossei,  wiU  always  keep  this  arrangement  in  the  memory  (see  diagram 
p ;  the  four  fine  lines  represent  the  axes  of  the  pahnar  muscles).  The  gen- 
eral disposition  of  the  interossei  may  be  summed  up  in  the  following  very 
simple  law :  All  the  dorsal  interossei  have  their  fixed  attachments  farther 
from  the  axis  of  the  hand  than  their  movable  one  ;  all  the  palmar  interossei 
have  their  fixed  attaclmients  nearer  to  the  axis  of  the  hand  than  their  movable  one. 

We  may  now  consider  the  general  arrangement  of  these  little  muscles. 

The  Dorsal  Interossei. 

These  are  short,  prismatic,  and  triangular  muscles  (d  to  d.  Jig.  123),  extending  from 
the  two  metacarpal  bones,  between  which  they  are  placed,  to  fHg.  123. 

the  first  phalanx  and  the  extensor  tendon  of  one  of  the  corre- 
spending  fingers.  They  arise  by  a  double  origin,  between 
which  the  perforating  arteries  pass.  But  while  one  of  these 
origins  is  limited  to  the  back  part  of  the  lateral  surface  of  one 
of  the  metacarpal  bones,  the  other  occupies  the  whole  length 
of  the  corresponding  lateral  surface  of  the  other  metacarpEd 
bone.  From  this  double  origin  the  fleshy  fibres  pass  obliquely 
forward  round  a  tendon,  which  only  emerges  from  them  near 
the  metacarpo-phalangal  articulation  ;  it  then  expands,  and  is 
inserted  partly  to  the  upper  end  of  the  first  phalanx  and  partly 
to  the  outer  edge  of  the  corresponding  extensor  tendon. 

Relations. — The  dorsal  interossei  correspond  behind  with  the 
dorsal  surface  of  the  hand  and  the  extensor  tendons,  from  which  they  are  separated  by 
a  very  thin  aponeurosis ;  in  front,  they  are  visible  in  the  palm  of  the  hand  by  the  sides  of 
the  palmar  interossei,  and,  like  the  latter,  are  covered  by  the  muscles  and  tendons  of  the 
palmar  region,  being  separated  from  those  parts  by  the  deep  pahnar  fascia.  A  distinct 
cellular  line,  or,  rather,  an  aponeurotic  septum,  intervenes  between  one  of  their  lateral 
surfaces  and  the  corresponding  palmar  interosseous  muscle  ;  the  other  lateral  surface  is 
in  relation,  through  its  entire  length,  with  the  metacarpal  bone  on  which  it  is  implanted. 

Action. — These  muscles  are  evidently  abductors  of  the  first  phalanges  of  the  fingers, 
the  axis  of  the  hand  being  taken  as  the  point  of  departure.  Their  insertion  into  the  ex- 
tensor tendons  explains  why  previous  extension  of  the  fingers  is  necessary  to  the  move- 
ment of  abduction. 

The  first  dorsal  interosseous  muscle  merits  a  special  description.  It  is  larger  than  the 
others,  on  account  of  the  greater  size  of  the  space  occupied  by  it ;  it  is  flat  and  triangu- 
lar, and  arises  by  two  origins,  separated,  not  by  a  perforating  branch,  but  by  the  radial 
artery  itself  A  fibrous  arch  completes  the  half  ring  formed  by  the  interval  between  the 
first  two  metacarpal  bones  for  the  passage  of  this  artery.  The  external  head  of  the 
muscle  arises  from  the  upper  half  of  the  inner  border  of  the  first  metacarpal  bone  ;  the 
internal  from  the  entire  length  of  the  external  surface  of  the  second  metacarpal  bone, 
and  from  the  hgaments  which  unite  it  to  the  trapezium.  From  these  points  the  fleshy 
fibres  proceed,  forming  two  thick  bundles,  which  are  perfectly  distinct  above,  and  con- 
verge to  a  tendon  that  is  attached  to  the  outer  side  of  the  first  phalanx  of  the  index  finger. 


264 


BIYOLOGY. 


Relations. — It  is  covered  behind  by  the  skin ;  it  corresponds  in  front  to  the  adductoi 
and  flexor  brevis  pollicis,  excepting  below,  where  it  is  sub-cutaneous.  Its  lower  edge, 
directed  obliquely  downward  and  inward,  is  immediately  sub-cutaneous,  and  crosses  the 
corresponding  edge  of  the  adductor  pollicis  at  a  very  acute  angle. 

The  Palmar  Interossei. 

These,  like  the  preceding,  are  short,  prismatic,  triangular,  and  penniform  muscles. 
They  are  three  in  number  (p  p  p,  fig.  123)  according  to  most  authors,  but  four  if  we  in- 
clude the  adductor  pollicis.  They  all  occupy  the  palm  of  the  hand,  as  their  name  indi- 
cates, and  extend  from  the  entire  length  of  one  of  the  metacarpal  bones  bounding  the 
interosseous  space  in  which  they  are  situated  to  the  first  phalanx  of  one  of  the  corre- 
sponding fingers,  and  to  its  extensor  tendon. 

They  arise  from  about  the  anterior  two  thirds  of  the  lateral  surface  of  only  one  meta- 
carpal bone  ;  they  are,  therefore,  covered  behind  by  the  dorsal  interossei,  wliich,  being 
attached  to  the  entire  lateral  surface  of  the  other  metacarpal  bone,  project  equally  into 
the  palm.  Lastly,  their  insertions  into  the  phalanges  and  their  extensor  tendons  corre- 
spond precisely  with  those  of  the  dorsal  interossei. 

Relations. — They  are  covered  by  the  flexor  tendons  and  by  the  muscles  of  the  palmar 
region  :  each  is  in  relation  behind  with  a  dorsal  interosseous  muscle  ;  on  one  side  with 
the  dorsal  muscle  of  the  corresponding  finger,  and  on  the  other  with  the  metacarpal  bone 
from  which  it  arises. 

Action. — They  are  evidently  adductors,  as  regards  the  axis  of  the  hand,  and,  like  the 
dorsal  interossei,  they  bind  down  the  extensor  tendons ;  they  can  only  act  effectuall) 
when  the  fingers  have  been  previously  extended. 


MUSCLES  OF  THE  LOWER  EXTREMITIES. 

The  muscles  of  the  lower  extremities  may  be  arranged  in  four  groups,  viz.,  those  ol 
the  pelvis,  of  the  thigh,  of  the  leg,  and  of  the  foot. 

MUSCLES  OF  THE  PELVIS. 

The  Glutcei,  Maximus,  Medius,  et  Minimus. — Pyriformis. — Obturator  Internus. — Gcmelb, 
Superior  et  Inferior. — Quadratus  Femoris. — Obturator  Externus. — Action  of  these  Muscles 

fig,  1S4,  The  muscles  of  the  pelvis  are  divided  into  those  occupy 

ing  the  posterior  and  those  occupying  the  anterior  region. 
The  former  are  very  numerous,  consisting  of  the  three  glutaei, 
maximus,  medius,  and  minimus,  the  pyriformis,  the  obturatoi 
internus,  the  gemelli,  the  quadratus  femoris,  and  the  obtura- 
tor externus. 

The  iliacus,  which  may  with  propriety  be  considered  as  be- 
longing to  the  pelvis,  and  as  forming  its  anterior vregion,  hsis 
been  already  described,  together  with  the  psoas,  under  the 
name  of  the  psoas-iliac  muscle. 

The  GlutcBUs  Maximus. 

Dissection. — Having  placed  the  subject  on  its  face,  raise  the 
pelvis  by  a  block,  flex  the  leg  forcibly,  and  rotate  it  inward ; 
then  make  an  oblique  incision  along  the  middle  of  the  but- 
tock, from  the  sacrum  towards  the  great  trochanter,  dividing 
both  the  skin  and  fascia  covering  the  muscle  :  dissect  up  the 
tw((  "aps,  one  from  below  upward,  the  other  from  above  down- 
wani,  following  the  direction  of  the  muscular  fibres. 

The  idutaus  maximus  {a,  fig.  124)  is  the  most  superficial  of 
the  muscles  on  the  posterior  aspect  of  the  pelvis  ;  it  is  broad, 
thick,  and  pretty  regidarly  quadrilateral ;  it  is  the  largest  mus- 
cle of  the  human  body,  in  this  respect  coinciding  with  the 
great  size  of  the  pelvis  and  femur  in  man  ;  it  causes  the  prom- 
inence of  the  buttocks.  Its  great  size  is  one  of  the  most  dis- 
tinctive characters  of  the  muscular  system  of  man,  and  has 
reference  to  his  biped  position. 

Attachments  (see  a,  fig.  125). — It  arises  from  the  posterior 
semicircular  line  of  the  ilium,  and  the  portion  of  the  bone  be- 
hind that  line  ;  from  the  vertical  sacro-iliac  ligament,  and  the 
outer  margin  of  the  common  aponeurosis  of  the  posterior  spi- 
nal muscles ;  from  the  crest  of  the  sacrum,  sometimes  only 
from  the  tubercles  which  form  a  continuation  of  the  trans- 
verse processes  of  the  vertebrae  on  the  outside  of  the  posteiior 


THE    GLUTiEUS    MEDIUS.  265 

sacral  foramina  ;  from  the  edges  of  the  coccyx,  and  the  notch  terminating  the  crest  of  the 
sacrum  below,  this  origin  being  often  effected  by  means  of  a  tendinous  arch,  under  which 
the  last  posterior  sacral  nerves  pass  ;  from  the  posterior  surface  of  the  great  sacro-sci- 
atic  ligament ;  and,  lastly,  from  the  posterior  surface  of  the  aponeurosis  of  the  glutseus 
medius.  It  is  inserted  {a,  fig.  125)  into  the  rough  line  leading  from  the  great  trochanter 
to  the  linea  aspera  of  the  femur. 

The  fleshy  fibres  arise  either  directly  or  by  short  tendinous  fibres,  and  proceeding  par- 
allel to  each  other  outward,  and  a  little  downward,  unite  into  large  distinct  fasciculi,  ca- 
pable of  being  separated  through  their  entire  length,  and  constituting  an  extremely  thick, 
quadrilateral,  and  very  regular  muscle,  which,  having  reached  the  outside  of  the  thigh, 
terminates  by  tendinous  fibres.  These  are  received  between  two  layers  of  the  fascia 
lata,  which  is  here  very  thick ;  in  passing  downward  they  converge,  escape  from  the 
fascia  lata,  curve  round  the  base  of  the  great  trochanter,  or,  rather,  the  tendon  of  the  vas- 
tus externus,  from  which  they  are  separated  by  a  synovial  bursa,  and  are  successively 
inserted  by  so  many  large  fasciculi  into  the  series  of  tubercles  and  depressions,  extend- 
ing from  the  great  trochanter  to  the  linea  aspera,  and  from  the  external  bifurcation  of 
that  line.  The  lower  fleshy  fibres  are  attached  directly  to  the  linea  aspera,  and  a  cer- 
tain number  are  inserted  merely  into  the  fascia  lata.  In  order  to  obtain  a  good  view  of 
the  femoral  insertions  of  this  muscle,  its  tendon  must  be  separated  from  the  fascia  lata. 

Relations. — It  is  covered  by  a  large  quantity  of  fat,  being  separated  from  it  by  an  ex- 
pansion from  the  aponeurosis  of  the  glutaeus  medius,  from  which  are  given  off  the  cellu- 
lar prolongations  that  divide  the  muscle  into  thick,  parallel,  and  easily  separable  fasciculi. 

It  covers  the  glutaeus  medius,  the  pyriformis,  the  gemelli,  the  obturator  internus,  the 
quadratus  femoris,  the  great  sciatic  notch,  and  the  tuberosity  of  the  ischium,  together 
with  the  muscles  attached  to  it,  viz.,  the  semi-tendinosus,  the  semi-membranosus,  and 
the  long  head  of  the  biceps.  It  covers  also  the  great  trochanter,  the  adductor  magnus, 
and  the  triceps  femoris,  the  glutaeal,  ischiatic,  and  internal  pudic  vessels  and  nerves,  and 
the  great  sciatic  nerves.  Its  upper  border  is  very  thin,  and  rests  upon  the  glutaeus  me- 
dius ;  its  lower  border  forms  a  very  marked  prominence  beneath  the  skin,  that  affords 
the  surgeon  very  precise  indications,  both  in  the  diagnosis  of  many  diseases  of  the  hip- 
joint  ;  in  operations  performed  for  the  purpose  of  reaching  the  tuberosity  of  the  ischium, 
when  it  is  either  carious  or  necrosed ;  in  those  for  the  relief  of  sciatic  hernia  ;  or,  lastly, 
in  searching  for  the  sciatic  nerve,  whenever  it  becomes  necessary  to  operate  upon  it. 
Several  bursae  mucosae,  which  have  been  well  described  by  Monro,  separate  the  glutaeus 
maximus  from  the  eminences  which  are  covered  by  it.  One  of  these  separates  it  from 
the  great  trochanter,  and  is  almost  always  multi-locular :  I  have  seen  it  filled  with  a  san- 
guineous synovia.  A  second  exists  over  the  tuberosity  of  the  ischium,  but  is  often  want- 
ing ;  and  a  third  between  the  tendon  of  this  muscle  and  the  vastus  externus.* 

Action. — The  glutaeus  maximus  is  an  extensor,  an  abductor,  and  a  rotator  of  the  thigh 
outward.  When  the  femur  is  fixed,  as  in  standing,  it  acts  upon  the  pelvis,  which  it  draws 
backward  and  to  its  own  side,  and  rotates  so  that  the  anterior  surface  of  the  trunk  is 
turned  to  the  opposite  side.  Besides  this,  it  is  easy  to  see  that  the  lower  fibres  can  act 
as  adductors.  By  its  connexions  with  the  fascia  lata,  it  is  one  of  the  principal  tensors  of 
this  structure ;  by  its  attachment  to  the  coccyx,  it  tends  to  prevent  that  bone  from  being 
thrown  backward,  forward,  or  to  one  side. 

The  Glut  (BUS  Medius. 

Dissection. — Make  a  vertical  incision  through  the  middle  of  the  glutaeus  maximus,  or 
detach  that  muscle  from  the  pelvis  ;  remove  the  adipose  tissue  from  the  sub-cutaneous 
portion  of  the  muscle,  and  also  the  fascia  lata  ;  dissect  the  tensor  vaginae  femoris,  which 
covers  the  anterior  fibres  of  this  muscle. 

The  glutaus  medius  (b,figs.  124  to  127)  is  intermediate  to  the  other  two  glutaei,  both  as 
regards  size  and  position ;  it  is  a  broad,  thick,  radiated  muscle,  situated  more  deeply 
than  the  preceding,  beyond  which  it  projects  upward  and  forward  (^fig.  124).  The  glu- 
taeus maximus  is  attached  to  a  small  portion  only  of  the  iliac  fossa :  the  glutaei  medius 
and  minimus  share  almost  the  whole  of  it  between  them. 

Attachments. — It  arises  from  the  whole  extent  of  the  curved  triangular  surface  included 
between  the  superior  semicircular  line  behind,  the  anterior  three  fourths  of  the  crest  of 
the  ilium  above,  and  the  inferior  semicircular  line  below ;  from  the  anterior  superior 
spine  of  the  ilium  and  the  notch  immediately  below  it ;  from  the  deep  surface  of  a  dense 
aponeurosis,  which  is  inserted  into  the  outer  lip  of  the  crest  of  the  ilium,  covers  all  the 
upper  portion  of  the  muscle,  and  becomes  continuous  with  the  fascia  lata  :  opposite  the 
junction  of  the  anterior  with  the  middle  third  of  the  crest  of  the  ilium,  at  which  point  a 
large  tubercle  exists  upon  the  bone,  this  aponeurosis  is  so  dense  as  to  resemble  a  tendon. 
The  muscle  also  arises  from  a  deep  aponeurosis,  extending  from  the  anterior  part  of  the 
inferior  semicircular  line,  and  giving  attachment,  on  its  external  surface,  to  a  great  num 
her  of  fleshy  fibres  ;  and,  lastly,  from  the  fascia  lata  internally  to  the  tensor  vaginae  femo 
ris.     It  is  inserted  into  the  external  surface  of  the  great  trochanter  {figs.  125,  127) 

*  See  note,  p.  296. 
L  L 


k 


266  MYOLOGY. 

From  these  numerous  origins  the  fleshy  fibres  proceed  in  different  directions ;  the  pos- 
terior forward,  the  middle  vertically,  and  the  anterior  backward,  becoming  more  and  more 
horizontal  in  front.  They  all  terminate  upon  the  two  surfaces  and  edges  of  a  radiated 
aponeurosis,  the  fibres  of  which  are  gradually  concentrated,  and  folded  upon  themselves, 
so  as  to  form  a  flat  tendon,  inserted,  not  into  the  upper  border,  as  it  is  generally  said,  but 
into  the  external  surface  of  the  great  trochanter,  along  an  oblique  line  running  downward 
and  forward,  so  that  the  anterior  fibres  of  the  muscle  are  inserted  into  the  anterior  ex- 
tremity of  the  lower  border  of  the  great  trochanter,  and  the  posterior  fibres  into  the  back 
part  of  the  upper  border ;  at  this  latter  point  a  well-marked  projection  sometimes  exists, 
the  size  of  which  generjdly  indicates  the  power  of  the  glutaeus  medius.  A  synovial  bursa 
intervenes  between  the  tendon  and  that  part  of  the  great  trochanter  over  which  it  passes.* 

Relations. — It  is  covered  by  the  glutaeus  maximus,  the  tensor  vaginas  femoris,  and  the 
skin :  it  covers  the  glutaeus  minimus,  with  which  its  outer  border  is  blended,  and  the 
glutaeal  vessels  and  nerves.     Its  lower  border  is  parallel  with  the  pyriformis  {fig.  125). 

Action. — The  glutaeus  medius  is  both  an  extensor  and  an  abductor  of  the  thigh.  More- 
over, the  anterior  fibres  rotate  the  femur  inward,  and  the  posterior  outward ;  but  the  for  • 
mer  have  the  greater  power,  for  they  are  more  numerous,  the  muscle  being  twice  or 
thrice  as  thick  in  front  as  behind ;  it  is,  therefore,  an  extensor,  an  abductor,  and  a  rotator 
inward  of  the  thigh.  Winslow  denies  that  it  is  an  extensor,  and  considers  it  only  as  an 
abductor ;  this  is  only  true  in  the  position  of  standing  upon  both  feet.  In  the  sitting  pos- 
ture, again,  this  muscle  in  some  degree  loses  its  power  as  an  extensor  and  abductor, 
and  acts  merely  as  a  rotator.  When  the  femur  is  fixed,  as  in  standing,  the  glutaeus 
medius  extends  the  pelvis,  draws  it  to  its  own  side,  and  rotates  it>  so  that  the  front  of 
the  trunk  is  turned  towards  the  same  side.  It  co-operates  with  the  glutaeus  maxunus  in 
the  first  two  motions,  but  antagonizes  it  in  the  last.  Finally,  its  anterior  fibres  appear 
to  me  calculated  to  flex  the  thigh  upon  the  pelvis,  especiaUy  when  the  flexion  has  been 
already  contmienced  by  other  muscles. 

The  Glutce.us  Minimus. 

The  glutaus  minimus  (c,fig.  127)  is  exposed  by  simply  cutting  across  the  preceding 
muscle,  beneath  which  it  lies  ;  it  is  thinner,  and  more  regularly  radiated.  It  arises  from 
the  anterior  part  of  the  crest  of  the  ilium,  below  the  glutaeus  medius,  from  the  outside  of 
the  sciatic  notch,  and  from  all  that  part  of  the  external  iliac  fossa  situated  below  the  in- 
ferior semicircular  line  :  from  these  points  the  fibres  converge,  the  middle  passing  ver- 
tically, the  posterior  forward,  and  the  anterior  backward,  to  the  deep  surface  of  a  radia- 
ted aponeurosis,  the  fibres  of  which  are  collected  together  into  bands,  that  are  inserted 
separately  into  the  anterior  border  and  anterior  half  of  the  upper  border  of  the  great  tro- 
chanter. Most  commonly  the  posterior  band  is  intimately  attached  to  the  tendon  of  the 
pyriformis. 

Relations. — It  is  covered  by  the  glutaeus  medius,  with  which  its  anterior  fibres  are 
blended ;  it  covers  the  external  iliac  fossa,  the  reflected  tendon  of  the  rectus  femoris, 
and  the  upper  part  of  the  hip-joint,  from  which  it  is  separated  by  some  fatty  cellular  tissue. 

Action. — It  is  much  more  directly  an  abductor  than  the  preceding  muscles.  Its  ante- 
rior half  rotates  the  thigh  inward,  and  its  posterior  half  outward.  If  the  femur  be  fixed, 
it  extends  the  pelvis,  inclines  it  to  its  own  side,  and  turns  the  anterior  aspect  of  the 
trunk  to  the  same  side  ;  by  its  anterior  fibres  it  assists  slightly  in  producing  flexion. 

General  Remarks  upon  the  Action  of  the  Glutcei. — The  three  muscles  we  have  just  ex- 
amined generally  have  their  fixed  points  upon  the  pelvis  ;  and,  in  this  point  of  view,  are 
of  the  greatest  importance  in  the  standing  posture.  By  their  means  the  pelvis,  firmly 
held  down  from  behind,  is  enabled  to  resist  the  effects  of  the  weight  of  the  trunk,  which 
tends  to  throw  it  forward  :  hence  the  enormous  development  of  these  muscles  in  man, 
evidently  proving  his  destination  for  the  erect  position.  These  same  muscles  are  the 
principal  agents  in  the  position  of  standing  upon  one  foot,  inclining  the  pelvis  to  their 
own  side,  and  balancing  the  entire  weight  of  the  opposite  side  of  the  trunk.  They  also 
rotate  the  trunk  when  the  individual  is  standing  upon  one  foot.  They  are  all  extensors 
and  abductors  ;  the  glutaeus  maximus  is  a  rotator  outward  ;  the  other  two  are  rotators 
inward.  Hence  we  may  understand  how  the  thigh  can  be  so  powerfully  rotated  inward, 
although  there  are  no  direct  muscles  for  that  purpose  ;  while  a  great  number  are  spe- 
cially intended  to  produce  rotation  outward,  which  movement,  indeed,  is  performed 
much  more  energetically  than  rotation  inward. 

The  Pyriformis. 

Dissection. — Detach  the  glutaeus  maximus,  and  separate  the  pyriformis  from  the  lowei 
border  of  the  glutaeus  medius,  to  which  it  is  parallel.  In  order  to  see  the  sacral  attach- 
ments of  the  muscle,  make  an  antero-posterior  section  of  the  pelvis. 

The  pyriformis  or  pyramidalis  {d,  fig.  125)  is  sometimes  double  :  it  is  a  flat  muscle,  of 
a  p5Tifonn,  or,  rather,  pyramidal  shape,  lying  almost  horizontally  along  the  lower  margin 
of  the  glutaeus  medius,  with  which  it  seems  to  be  continuous,  and  is  sometimes  intimately 

*  See  note,  p.  296. 


THE  OBTURATOR  INTERNUS.  267 

united :  it  is  partly  situated  in  the  cavity  of  the  pelvis,  and  assists  in  filling  up  the  sciat- 
ic notch. 

Attachments. — It  arises  from  the  anterior  surface  of  the  sacrum  (p,^.  Ill),  in  the  in- 
tervals between  the  grooves  forming  the  continuations  of  the  anterior  sacral  foramina, 
and  also  opposite  those  grooves,  by  three  or  four  digitations,  which  are  sometimes  trav- 
ersed by  the  great  sciatic  nerve  :  these  origins  are  sometimes  concentrated  into  a  small 
space  around  the  second  and  third  anterior  sacral  foramina.  It  also  arises  from  the  an- 
terior surface  of  the  great  sacro-sciatic  ligament,  and  from  the  upper  part  of  the  sciatic 
notch.  It  is  inserted  into  the  back  part  of  the  upper  edge  of  the  great  trochanter.  The 
fleshy  fibres  pass  irom  their  origins  almost  horizontally  outward  and  a  little  backward, 
and  form  a  muscle  which  fills  up  the  upper  part  of  the  great  sciatic  notch,  and,  becoming 
much  narrower  immediately  after  emerging  from  the  pelvis,  from  the  convergence  of  its 
fibres,  terminates  on  the  posterior  surface  and  edges  of  an  aponeurosis,  which  is  after- 
ward converted  into  a  round  tendon,  and  is  fixed  to  the  upper  border  of  the  great  tro- 
chanter, behind  the  glutaeus  minimus,  and  above  the  gemelU  and  obturator  internus,  with 
which  it  is  almost  always  intimately  connected. 

Relations. — Its  anterior  surface  is  in  relation  with  the  rectum,  the  sciatic  plexus,  and 
the  hypogastric  vessels  within  the  pelvis,  and  with  the  hip-joint  outside  that  cavity ;  its 
posterior  surface,  with  the  sacrum  and  the  glutaeus  maximus ;  its  upper  margin,  with  the 
glutaeal  vessels  and  nerves,  which  separate  it  from  the  glutaeus  medius  ;  its  lower  mar- 
gin, with  the  ischiatic  vessels,  and  with  the  great  and  small  sciatic  nerves.  Sciatic  her- 
niae  take  place  between  the  upper  margin  of  this  muscle  and  the  sciatic  notch.  Some- 
times the  muscle  reaches  the  summit  of  the  notch  ;  occasionally,  a  considerable  interval 
exists  between  them ;  in  such  cases,  there  is  a  predisposition  to  this  species  of  hemiae. 

The  Obturator  Internus. 

The  oUurator  internus  {e,fig.  125)  is  a  triangular  reflected  muscle,  extending  from  the 
inner  surface  of  the  margin  of  the  obturator  foramen  to  the  digital  cavity  of  the  great 
trochanter.    Its  course  and  direction  are  alike  remarkable. 

Attachments. — It  arises  from  the  posterior  surface  of  the  obturator  ligament,  from  the 
pelvic  fascia  lining  the  inner  surface  of  this  muscle,  and  from  the  tendinous  arch  which 
converts  the  sub-jmbic  groove  into  a  canal ;  also,  from  the  entire  circumference  of  the  ob- 
turator foramen,  viz.,  from  the  internal  surface  of  the  descending  ramus  of  the  pubes  and 
the  ascending  ramus  of  the  ischium,  and  from  the  whole  extent  of  the  quadrilateral  sur- 
face situated  between  the  obturator  foramen  and  the  sciatic  notch  ;  and,  lastly,  by  a  few 
fibres  from  the  brim  of  the  pelvis.  It  is  inserted  into  the  digital  cavity  of  the  great  tro- 
chanter. The  fleshy  fibres  arise  directly  from  this  extensive  surface,  and,  converging 
downward  and  outward,  pass  out  of  the  pelvis  through  a  triangular  opening  formed  by  the 
spine  of  the  ischium  and  lesser  sacro-sciatic  ligament  above,  by  the  great  sacro-sciatic 
ligament  on  the  inside,  and  by  the  body  of  the  ischium  on  the  outside.  At  its  exit  from 
the  pelvis  the  muscle  becomes  much  narrower,  is  reflected  at  a  right  angle  over  the  body 
of  the  ischium  as  over  a  pulley,  is  next  received  into  a  groove  formed  for  it  by  the  gemelli, 
and  proceeds  horizontally  outward,  to  be  inserted  into  the  digital  cavity  of  the  great  tro- 
chanter below  the  pyriformis.  In  order  to  obtain  a  good  view  of  the  structure  of  this 
muscle,  it  must  be  detached  from  its  insertion  and  turned  inward.  We  shall  then  per- 
ceive that  the  tendon  divides  into  four  or  five  diverging  portions  upon  the  deep  surface 
of  the  muscle,  which  are  lost  in  its  interior.  A  well-marked  synovial  membrane*  inter- 
venes between  the  tendon  and  the  trochlear  surface  on  the  body  of  the  ischium,  which 
is  covered  with  cartilage  that  is  streaked,  as  it  were,  in  the  direction  of  the  movements. 
Cowper  and  Douglas  alluded  to  the  presence  of  this  bursa  when  they  named  the  muscle 
marsupialis  vel  bursalis. 

Relations. — In  the  pelvis  the  obturator  internus  is  in  relation  with  the  obturator  liga- 
ment and  the  circumference  of  the  obturator  foramen,  by  its  anterior  surface  ;  and  with 
the  pelvic  fascia  and  levator  ani  muscle,  which  separates  it  from  the  bladder,  by  its  pos- 
terior surface.  During  its  passage  through  the  orifice  I  have  described,  it  is  in  relation 
with  the  internal  pudic  vessels  and  nerves ;  externally  to  the  pelvis,  it  is  covered  by  the 
great  sciatic  nerve  and  the  glutaeus  maximus,  and  it  covers  the  hip-joint. 

From  the  great  extent  of  the  pelvic  origins  of  this  muscle,  almost  the  whole  of  the  an- 
terior and  lateral  parietes  of  the  pelvis  are  covered  internally  by  a  layer  of  muscular  tis- 
sue ;  the  posterior  wall  is  also  in  a  great  measure  covered  by  the  pyriformis. 

The  origin'  of  the  muscular  fibres  from  the  tendinous  arch  of  the  obturator  ligament 
are  so  arranged,  that  the  contraction  of  the  muscle  can  have  no  effect  in  diminishing  the 
size  of  the  sub-pubic  foramen  intended  for  the  passage  of  vessels  and  nerves.  There 
are  sometimes  two  small  tendinous  arches  ;  one  for  the  nerve,  the  other  for  the  artery 
and  vein. 

The  Gemelli,  Superior  et  Inferior. 
The  gemelli  (gemini,  Albinus ;  les  petits  jumeaux,  Winslaw,  f  and  g,  Jig.  135),  two  small 

1  See  note,  p.  295. 


268  MYOLOGY. 

fleshy  fasciculi,  accessories  to  the  obturator  intemus,  are  generally  distinguished  by  anat- 
omists into  the  superior  (/)  and  the  inferior  (g) ;  they  are  separated  from  each  other  by 
the  tendon  of  the  obturator  intemus,  for  the  reception  of  which  they  form  a  groove. 
Above  and  below  this  groove  they  take  their  origin  ;  the  superior  from  the  spine  of  the 
ischium,  and  the  inferior,  which  is  the  larger,  from  the  tuberosity  of  that  bone,  immedi- 
ately above  the  attachment  of  the  great  sacro-sciatic  ligament,  and  even  slightly  from 
the  ligament  itself  They  both  pass  horizontally  outward,  are  sometimes  united  either 
behind  or  in  front  of  the  tendon  of  the  obturator  intemus,  which  they  then  completely 
embrace,  and  with  which  they  are  entirely  or  partially  blended,  being  inserted  with  it  into 
the  digital  cavity  of  the  great  trochanter. 

Their  relations  are  the  same  as  those  of  the  reflected  portion  of  the  obturator  intemus. 
The  gemellus  superior  is  often  wanting,  and  the  inferior  is  frequently  double.  I  have 
several  times  seen  the  superior  terminate  in  the  tendon  of  the  pyriformis,  and  the  in- 
ferior in  the  tendon  of  the  obturator  intemus. 

Actimi. — They  rotate  the  thigh  outward.  Their  relations  with  the  synovial  capsule  of 
the  obturator  intemus  led  to  their  being  designated  marsupiales  by  Cowper,  and  by  Portal, 
le  muscle  capsulaire  de  la  capsule  du  tendon  de  I'obturateur  interne. 

The  Quadratus  Femoris. 

This  muscle  (i,  fig.  125),  shaped  like  a  parallelogram,  is  situated  immediately  below 
the  gemellus  inferior.  It  arises  from  the  external  border  of  the  tuberosity  of  the  ischium, 
in  front  of  the  semi-membranosus,  from  which  it  is  separated  by  adipose  tissue.  From 
this  point  the  fibres  proceed  horizontally  outward,  parallel  to  each  other,  and  are  inserted 
into  "  an  oblong  ridge*  projecting  partly  from  the  back  of  the  root  of  the  great  trochan- 
ter, and  partly  from  the  femur  immediately  below  it ;"  but  above  the  attachment  of  the 
adductor  magnus,  with  which,  at  first,  it  appears  to  be  continuous,  but  from  which  it  is 
always  separated  by  the  internal  circumflex  vessels. 

This  muscle  is  sometimes  wanting ;  but  very  frequently  its  pelvic  attachments  are  pro- 
longed as  far  as  the  ascending  ramus  of  the  ischium  ;  in  which  cases  it  is  twisted  inferi- 
orly  upon  itself,  so  as  to  oppose  a  surface,  not  a  border,  to  the  adductor  magnus.  Its  re- 
lations behind  are  the  same  as  those  of  the  preceding  muscles ;  in  front,  it  covers  the 
obturator  externus  and  the  lesser  trochanter,  from  which  it  is  often  separated  by  a  sy- 
novial capsule. 

The  Obturator  Externus. 

Dissection. — The  lower  or  horizontal  portion  of  the  obturator  externus  is  exposed,  by 
dividing  the  quadratus  femoris  into  two  equal  parts  by  a  vertical  incision.  In  order  to 
see  the  upper  or  pelvic  portion,  it  is  necessary  to  detach  the  gracilis,  pectineus,  psoas,  ili- 
acus,  and  adductor  brevis. 

This  is  a  triangular,  flat  muscle  (e,  fig.  127),  of  the  same  shape,  but  thinner  and  smallei 
than  the  obturator  intemus,  and,  like  it,  reflected,  though  at  an  obtuse  angle.  It  arises 
from  the  circumference  of  the  obturator  foramen,  from  the  obturator  ligament,  and  from 
the  tendinous  arch  which  completes  the  sub-pubic  canal  for  the  vessels  and  nerve.  It 
is  inserted  into  the  deepest  and  lowest  part  of  the  digital  cavity  of  the  great  trochanter. 
The  fleshy  fibres  arise  directly,  the  lower  ones  proceed  horizontally  outward,  and  the 
upper  obliquely  downward,  backward,  and  outward  ;  thus  converging,  they  form  a  fleshy 
belly,  which  turns  round  the  neck  of  the  femur,  and  terminates  in  a  tendon  that  passes 
horizontally  outward,  to  be  inserted  into  the  digital  cavity,  below  the  gemelli  and  the  ob- 
turator intemus. 

Relations. — Its  outer  and  anterior  surface  is  in  relation  with  the  pectineus,  the  adduc- 
tors, the  psoas  and  iliacus  muscles,  and  more  externally  with  the  neck  of  the  femur  and 
the  lower  part  of  the  capsular  ligament  of  the  hip-joint.  Its  inner  and  posterior  surface 
is  in  contact  with  the  obturator  foramen  and  the  quadratus  muscle. 

Action  of  the  preceding  Muscles. 

The  last  six  muscles  are  evidently  rotators  of  the  thigh  outward.  The  pyriformis,  the 
gemelli,  and  the  obturator  internus,  which  are  almost  always  united  at  their  insertions, 
would  deserve  the  name  of  quadri-gemini,  given  by  the  older  anatomists  to  the  gemeUi, 
the  pyriformis,  and  the  quadratus.  When  they  take  their  fixed  point  upon  the  femur,  as, 
for  example,  in  standing  upon  one  foot,  they  become  rotators  of  the  pelvis,  and  turn  the 
anterior  surface  of  the  trunk  to  the  opposite  side.  They  are  only  rotators  when  tlie  limb 
is  extended  ;  in  the  sitting  posture,  they  become  abductors.  Winslow,  who  first  demon- 
strated their  use  in  abduction  in  the  semiflexed  position,  attached  great  importance  to 
the  connexion  of  so  many  of  these  muscles  with  the  capsular  ligament,  which  he  believed 
prevented  pinching  of  the  capsule  during  the  different  movements  of  the  joint. 

The  insertion  of  these  muscles  is  exceedingly  favourable.  Moreover,  we  shall  find, 
that  besides  the  glutaeus  maximus  and  the  posterior  fibres  of  the  glutaeus  medius  and 

*  [M.  Cruveilhier  states  the  insertion  of  the  quadratus  femoris  to  be  into  the  inter-trochanteric  line.  Tba 
description  in  the  text,  copied  from  Albinus,  gives  a  more  accurate  idea  of  the  insertion  of  this  muscle.] 


THE   BICEPS   CRURIS. 


minimus,  they  have  many  other  muscles  as  accessories  in  rotation.  The  effects  pro- 
duced by  the  contraction  of  the  two  obturators  can  be  easily  understood,  if  we  bear  in 
mind  that  the  action  of  a  reflected  muscle  is  to  be  calculated  from  the  point  of  reflection, 
leaving  the  rest  of  the  muscle  out  of  consideration.  Thus,  with  regard  to  the  obturator 
internus,  the  sciatic  notch  acts  as  a  pulley,  and  may  be  regarded  as  the  fixed  point. 


MUSCLES  OF  THE  THIGH. 

The  Biceps  Cruris. — Semi-tendinosus. — Semi-memhranosus. — Tensor  Vagina.  Femoris. — 
Sartorius. — Triceps  Extensor  Cruris. — Gracilis. — Adductor  Muscles  of  the  Thigh. 

The  muscles  of  the  thigh  are  divided  into  those  of  the  posterior  region,  viz.,  the  biceps, 
the  semi-tendinosus,  and  the  semi-membranosus  ;  those  of  the  external  region,  viz.,  the 
tensor  vaginae  femoris  and  the  vastus  externus  ;  those  of  the  anterior  region,  viz.,  the 
sartorius,  the  rectus,  and  the  triceps  extensor  cruris  of  authors ;  and,  lastly,  those  of  the 
internal  region,  viz.,  the  gracilis,  the  pectineus,  and  the  three  adductors. 

Posterior  Region. 

The  Biceps  Cruris. 

Dissection. — This  is  the  same  for  the  biceps,  the  semi-tendinosus,  and  the  semi-mem- 
branosus. Place  the  subject  upon  its  face,  with  a  block  under  the  pelvis,  and  allow  the 
leg  to  hang  over  one  side  of  the  table.  Make  an  incision  from  the  middle  of  the  space 
between  the  tuberosity  of  the  ischium  and  the  great  trochanter  to  the  interval  between 
the  two  condyles  of  the  femur.  Both  the  skin  and  the  fascia  of  the  thigh  must  be  di- 
vided in  this  incision.  Cautiously  remove  the  cellular  and  adipose  tissue  surrounding 
the  subjacent  muscles,  the  relations  of  which  with  the  popliteal  vessels  and  nerves  must 
be  carefully  studied.  In  preparing  the  superior  attachments  of  these  muscles,  the  glu 
iaeus  maxiraus  must  be  divided  in  the  middle,  perpendicularly  to  its  fibres. 

The  biceps  femoris  (biceps  cruris,  Albinus,  I,  figs.  124,  125),  so  named  because  it  con- 
sists of  two  fleshy  bodies  or  heads  above,  is  a  long,  large  muscle,  situated  on  the  poste- 
rior and  external  aspect  of  the  thigh. 

Attachments. — It  arises  from  the  tuberosity  of  the  ischium  and  the  linea  aspera  of  the 
femur,  and  is  inserted  into  the  head  of  the  fibula,  and  slightly  jp^.  125. 

into  the  external  tuberosity  of  the  tibia.     Its  origin  from  the 

ischium  {I,  fig.  125)  is  common  to  it  and  the  semi-tendinosus  ;  -;;  ■;  ^^f ; 

it  takes  place,  not  from  the  tuberosity  properly  so  called,  but 
from  the  highest  and  most  external  part  of  the  tuberosity, 
above  and  behind  the  adductor  magnus,  and  immediately  be- 
low the  gemellus  inferior.  It  arises  by  a  tendon  which  is  sel- 
dom completely  free  from  muscular  fibres.  This  tendon,  at 
first  very  thick,  and  separated  from  the  tuberosity  of  the 
ischium  by  a  synovial  bursa,  expands  into  an  aponeurosis, 
which  gives  origin  to  the  fleshy  fibres  of  the  biceps  by  its  ex- 
ternal edge  and  posterior  surface,  and  to  those  of  the  semi- 
tendinosus  by  its  internal  surface.  Up  to  this  point  the  biceps 
and  semi-tendinosus  are  blended  together  so  as  to  form  a  single 
fleshy  belly,  which,  after  extending  from  two  to  four  inches,  is 
divided  into  two  portions  :  one  posterior  and  external,  consti- 
tuting the  long  head,  or  ischiatic  portion  of  the  biceps ;  the  other 
anterior,  forming  the  origin  of  the  semi-tendinosus,  which  we 
shall  next  describe.  Arising  thus  in  succession,  the  fleshy 
fibres  of  the  long  head  of  the  biceps  form  a  fusiform  belly 
passing  obliquely  downward  and  a  little  outward,  and  termina- 
ting on  the  anterior  surface  of  an  aponeurosis,  which  extends 
for  a  considerable  distance  on  the  posterior  surface  of  the 
muscle,  and  which  gradually  becomes  contracted,  so  as  to 
form  the  terminal  tendon.  Just  where  these  fleshy  fibres  are 
about  to  terminate  {l,Jig.  125),  the  aponeurosis  receives  upon 
its  anterior  surface  and  external  edge  the  fleshy  fibres  of  the 
short  head,  or  femoral  porticm  of  the  biceps.  This  portion  of 
the  muscle  {I',  fig.  125)  arises  from  the  greater  part  of  the  in- 
terval between  the  two  margins  of  the  linea  aspera,  and  the 
posterior  surface  of  the  external  inter-muscular  septum  of  the 
thigh ;  it  passes  downward,  inward,  and  backward,  to  be  at- 
'.ached  to  the  common  tendon,  almost  as  far  as  its  insertion. 
This  insertion  is  not  confined  to  the  head  of  the  fibula,  but  extends  also  to  the  external 
tuberosity  of  the  tibia  by  means  of  a  strong  division  of  the  tendon,  which,  at  the  same 
time,  gives  ofF^n  expansion  to  the  fascia  of  the  leg.    The  insertion  into  the  fibula  is  ef- 


2^0  MYOLOGY. 

fected  on  the  outer  side,  in  front  of  and  behind  the  extemzd  lateral  ligament  of  the  knee- 
joint,  which  ligament  it  embraces  in  a  bifurcation. 

Relations. — The  biceps  is  covered  by  the  glutaeus  maximus  and  the  femoral  fascia.  It 
covers  the  semi-tendinosus,  semi-membranosus,  and  vastus  externus.  It  is  in  relation, 
also,  with  the  great  sciatic  nerve,  which  is  placed  at  first  externally,  then  in  front,  and, 
lastly,  on  the  inside  of  the  muscle  ;  finally,  its  short  head  is  in  relation  with  the  popliteal 
vessels. 

The  biceps  forms  the  external  border  of  the  popliteal  space  ;  near  its  termination  it 
is  in  relation  with  the  outer  head  of  the  gastrocnemius  and  with  the  plantaris  longus 
muscle. 

Action. — The  biceps  flexes  the  leg  upon  the  thigh.  When  this  movement  is  com- 
pleted, its  long  portion  extends  the  thigh  upon  the  pelvis.  From  its  obliquity  downward 
and  outward,  it  rotates  the  leg  outward  during  semi-flexion  ;  but  this  rotation  is  impos- 
sible when  the  leg  is  extended,  in  consequence  of  the  tension  of  the  crucial  ligaments. 
The  fixed  point  of  this  muscle  is  as  often  below  as  above,  and  it  then  performs  an  im- 
portant part  in  the  mechanism  of  standing  ;  for  it  tends  to  prevent  the  individual  from 
ialhng  forward,  because  it  holds  back  the  pelvis.  When  the  pelvis  is  thrown  quite  back- 
ward, this  muscle  can  then  flex  the  thigh  upon  the  leg. 

The  Semi-tendinosus. 

The  semi-tendinosus  {m,figs.  124,  125),  so  named  on  account  of  the  great  lengta  of  its 
tendon,  is  situated  on  the  posterior  and  internal  aspect  of  the  thigh. 

AttcLchments. — It  arises  from  the  tuberosity  of  the  ischium,  and  is  inserted  into  the  an- 
terior tuberosity  of  the  tibia.  Its  origin  (m,  fig.  125)  consists  of  a  tendon  common  to  it 
and  the  long  head  of  the  biceps,  which  is  prolonged  in  the  form  of  an  aponeurosis,  upon 
the  external  (or  popliteal)  border  of  the  muscle.  Some  of  the  fleshy  fibres  are  attached 
directly  to  the  tuberosity  of  the  ischium.  Having  arisen  in  this  manner,  it  enlarges  and 
constitutes  a  fusiform  bundle,  which  passes  at  first  vertically  downward,  and  then  ob- 
liquely inward.  About  four  or  five  fingers'  breadth  above  the  knee-joint  it  terminates  in 
a  long,  thin  tendon,  which  turns  round  the  internal  tuberosity  of  the  tibia,  describing  a 
curve  having  its  concavity  directed  forward,  and  is  then  reflected  horizontally  forward, 
to  be  inserted  into  the  anterior  teberosity  of  that  bone,  behind  the  tendon  of  the  sarto- 
rius,  and  parallel  with  the  lower  edge  of  that  of  the  gracilis,  to  which  it  is  united.  The 
union  of  these  three  tendons  constitutes  the  patte  d'oie  (goose's  foot). 

The  length  of  its  tendon  of  insertion  is  the  most  characteristic  feature  of  the  muscle ; 
and  hence  its  name,  semi-nervosus  (Spigelius),  and  le  demi-nerveux  ( Winslow),  for  which 
the  term  semi-tendinous  has  now  been  substituted.  The  structure  oi  this  muscle  is  re- 
markable. The  fleshy  fibres  are  interrupted  across  the  middle  by  a  tendinous  intersec- 
tion, analogous  to  that  of  the  great  complexus,  which  gives  origin  to  new  fleshy  fibres. 

Relations. — It  is  covered  by  the  glutaeus  maximus  and  the  femoral  fascia,  and  it  cov- 
ers the  semi-membranosus  and  part  of  the  upper  portion  of  the  adductor  magnus.  Its 
tendon  is  first  placed  behind  the  semi-membranosus,  and  then,  before  it  turns  round  the 
internal  tuberosity  of  the  tibia,  between  the  tendon  of  that  muscle  and  the  inner  head  of 
the  gastrocnemius. 

Action. — ^The  same  as  that  of  the  biceps.  It  is  a  very  powerful  flexor,  on  account  of 
the  reflection  of  its  tendon.  Its  oblique  direction  enables  it  to  rotate  the  tibia  inward  du 
ring  semi-flexion  of  the  leg.     It  is,  therefore,  a  congener  of  the  popliteus. 

The  Semi-membranosus. 

The  semi-membranosus  {n,figs.  124,  125)  is  situated  upon  the  posterior  aspect  of  the 
thigh,  thin  and  aponeurotic  above,  thick  and  fleshy  below. 

Attachments. — It  arises  from  the  upper  and  outermost  part  of  the  tuberosity  of  the  is- 
chium, in  front  of  the  biceps  and  semi-tendinosus  ;  and  is  inserted  into  the  internal  tuber 
osity  of  the  tibia,  and  also,  by  an  expansion  of  its  tendon,  into  the  femur.  It  arises  by 
means  of  a  very  thick  tendon,  which  becomes  wider  immediately  after  its  origin.  From 
its  inner  border  is  given  off"  an  aponeurotic  lamina,  that  splits  into  two  layers,  from  the  in- 
terval between  which  the  superior  fleshy  fibres  arise.  Lower  down,  the  muscular  fibres 
proceed  directly  from  the  tendon  itself,  which  runs  along  the  outer  (or  popliteal)  border 
of  the  muscle,  as  far  as  the  lower  fourth  of  the  thigh,  but  is  afterward  buried  in  its  sub- 
stance. The  union  of  all  these  fibres  constitutes  a  very  thick,  four-sided,  fleshy  belly, 
which  is  received  into  a  tendinous  semi-cone,  open  on  its  outer  side,  and  soon  becoming 
converted  into  a  thick  tendon,  which,  after  a  passage  of  a  few  lines,  separates  into  three 
divisions,  terminating  in  the  following  manner :  the  posterior  division  passes  inward  and 
upward,  forms  the  chief  part  of  the  posterior  ligament  of  the  knee-joint,  and  is  inserted 
into  the  femur ;  the  middle  division  is  attached  to  the  back  of  the  internal  tuberosity  of 
the  tibia,  below  the  articular  surface  ;  the  third  is  horizontal,  and  turns  round  the  inter- 
nal tuberosity  of  that  bone  in  the  horizontal  furrow  existing  there,  and  is  inserted  on  the 
inner  side  of  the  tuberosity.     A  synovial  bursa  intervenes  between  it  and  the  bone. 

Relations. — The  semi-membranosus  is  covered  by  the  glutaeus  maximus,  the  semi-ten- 


THE    TENSOR    VAGINA    FEMORIS. THE    SARTORIUS.  271 

dinosus,  the  biceps,  and  the  femoral  fascia :  it  covers  the  quadratus  femoris,  the  adduc- 
tor niagnus,  and  the  inner  head  of  the  gastrocnemius.  A  synovial  membrane  separates 
it  from  the  knee-joint.  It  also  covers  the  popliteal  artery  and  vein,  which  soon  come 
into  relation  with  its  outer  or  popliteal  border.  The  sciatic  nerve  lies  parallel  with  its 
outer  border  through  the  whole  of  its  extent ;  the  gracilis  is  in  contact  with  its  inner 
border.  I  shall  remark  here,  that  the  biceps  on  the  outside,  and  the  semi-membranosus 
and  semi-tendinosus  on  the  inside,  constitute  the  lateral  boundaries  of  a  cellular  interval 
which  extends  along  the  whole  of  the  back  of  the  thigh,  and  is  continuous  with  the  pop- 
liteal space.  This  large  cellular  interval  communicates  above  with  the  cellular  tissue 
of  the  pelvis  at  the  sciatic  notch,  and  below  with  the  fossa  of  the  ham.  It  is  in  this  di- 
rection that  purulent  matter  so  readily  escapes  from  the  pelvis.  The  greater  part  of 
this  interval  is  destined  for  the  great  sciatic  nerve,  which,  however,  is  soon  accompani- 
ed by  the  popliteal  vessels. 

Action. — Precisely  similar  in  nature  to  that  of  the  preceding  muscle,  but  much  more 
powerful.  The  momentum  of  all  these  flexor  muscles  occurs,  on  the  one  hand,  during 
semi-flexion  of  the  leg  upon  the  thigh  ;  and,  on  the  other  (i.  e.,  when  their  lower  attach- 
ments are  fixed),  during  semi-flexion  of  the  thigh  upon  the  pelvis. 

External  Region. 

The  Tensor  Vagince  Femoris. 

Dissection. — In  order  to  expose  this  muscle,  it  is  sufficient  to  make  a  vertical  incision 
through  the  thick,  tendinous  layer  given  off  from  the  anterior  portion  of  the  crest  of  the 
ilimn,  and  to  dissect  back  the  two  flaps  of  that  aponeurosis. 

The  tensor  vagina  femoris  (le  muscle  du  fascia  lata,  o,fig.  126)  is  the  largest  of  all  the 
extensor  muscles  of  aponeuroses  :  it  is  a  short,  flat,  quadrilateral  muscle,  contained  within 
the  substance  of  the  fascia  lata,  and  occupying  the  upper  third  of  the  external  region  of 
the  thigh.  It  arises  from  the  anterior  part  of  the  outer  margin  of  the  crest  of  the  ilium, 
and  from  the  outer  border  of  the  anterior  superior  spinous  process  of  the  ilium,  between 
the  sartorius  and  the  glutasus  medius,  by  means  of  a  tendon,  which  also  furnishes  some 
points  of  attachment  to  the  anterior  fibres  of  the  last-named  muscle.  From  these  points 
the  fleshy  fibres  proceed  downward  and  a  little  backward,  and,  at  about  the  upper  fourth 
or  third  of  the  thigh,  terminate  in  a  series  of  small  tendinous  bundles,  the  anterior  of 
which  become  continuous  with  the  fascia  lata,  while  the  posterior  cross  obliquely  over 
the  vertical  fibres  of  the  fascia,  with  which  they  are  very  soon  blended. 

Relations. — It  lies  between  two  layers  of  the  fascia  lata,  the  external  layer  being  much 
thicker  than  the  internal.  It  is  covered  by  the  skin,  and  it  covers  the  glutaeus  medius, 
the  rectus,  and  the  vastus  extemus.  Its  anterior  border  is  in  contact  with  the  outer 
edge  of  the  sartorius,  but  is  soon  separated  from  it  by  a  triangular  space,  in  which  the 
rectus  femoris  may  be  seen.  ' 

Action. — It  is  a  tensor,  not  only  of  the  entire  femoral  fascia,  but  particularly  of  the  very 
dense  portion  or  band  of  the  fascia  lata,  which,  being  continuous  with  it,  may  be  regard- 
ed as  an  aponeurotic  tendon  to  this  muscle  (muscle  aponeurotique  de  la  bande  large, 
Winslow),  and  which  is  inserted  into  the  outer  tubercle  of  the  anterior  tuberosity  of  the 
tibia,  and  into  the  adjacent  part  of  its  external  tuberosity.  When  the  tensor  vaginae  is 
in  action,  this  band  compresses  the  vastus  extemus,  which  has  so  great  a  tendency  to 
displacement ;  by  means  of  this  band,  also,  the  muscle  acts  upon  and  extends  the  leg. 
Lastly,  on  account  of  its  slight  obliquity  downward  and  backward,  it  may  be  regarded  as 
a  rotator  of  the  thigh  inward  ;  it  is  but  little  concerned,  however,  in  the  production  of 
this  movement,  which,  as  I  have  already  said,  is  chiefly  effected  by  the  anterior  fibres 
of  the  glutaei  medius  and  minimus. 

Anterior  Region. 

The  Sartorius. 

Dissection. — This  is  common  to  all  the  muscles  of  the  anterior  and  inner  regions  ol 
the  thigh.  Make  a  horizontal  incision  along  the  fem.oral  arch,  and  another  perpendicu- 
larly from  the  middle  of  that  to  the  anterior  tuberosity  of  the  tibia.  Dissect  the  fascia 
of  the  thigh  with  care.  As  all  the  muscles  of  the  anterior  and  inner  region  are  separa- 
ted from  each  other  by  distinct  sheaths,  their  dissection  consists  simply  in  opening  these 
sheaths  successively,  and  removing  the  cellular  tissue  that  fills  up  the  inter-muscular  spa- 
ces. It  is  necessary  to  preserve  the  vessels,  in  order  to  obtain  a  good  view  of  their  rela- 
tions :  avoid  opening  the  vena  saphena,  as  it  generally  contains  a  large  quantity  of  blood, 
the  escape  of  which  will  impede  the  dissection.  If  the  vein  should  be  opened,  it  must  be 
tied  above  and  below  the  orifice,  and  then  cut  across.  When  the  superficial  muscles 
have  been  studied,  they  must  be  divided  in  the  middle,  in  Order  to  expose  the  muscles 
of  the  deep  layers. 

The  sartorius  {p,  fig.  126),  so  named  on  account  of  its  uses,  crosses  diagonally  over  the 
anterior,  and  then  the  inner  part  of  the  thigh,  to  the  top  of  the  leg.  It  is  the  longest  mus- 
cle in  the  body,  both  as  regards  its  total  length,  and  more  especially  in  reference  to  the 


«72 


MYOLOGY. 


Fig- 126.  length  of  its  fibres ;  whence  the  name  of  longus,  given  to  it  by 

Riolanus.     This  is  the  case  even  although  it  be  nneasured  by  a 
line  stretched  directly  between  its  two  extremities. 

Attachments. — It  arises  from  the  anterior  superior  spinous  pro- 
cess of  the  ilium,  from  the  upper  half  of  the  notch  below  that  pro- 
cess, and  from  a  tendinous  septum  between  the  muscle  and  the 
fascia  lata.  It  is  inserted  into  the  inner  margin  of  the  crest  of  the 
tibia,  situated  beneath  the  ligamentum  patellae.  Its  origin  con- 
sists of  some  tendinous  fibres,  which  are  more  marked  beb  md  and 
on  the  outer  side  than  in  front  and  within.  The  fleshy  fibres 
commence  almost  immediately,  and  form  a  flat,  riband-like  mus- 
cle (fascialis,  Spigelius),  which  in  reality  is  prismatic  and  trian- 
gular, as  well  as  the  tendinous  sheath  in  which  it  is  enclosed. 
The  muscle  increases  in  breadth  as  far  as  the  lower  third  of  the 
thigh,  and  passes  obliquely  downward,  inward,  and  a  little  back- 
ward ;  it  becomes  internal  and  vertical  at  the  lower  third  (p,  Jigs. 
124,  125),  and  reaches  the  back  part  of  the  inner  condyle  of  the 
femur,  to  turn  round  the  knee-joint,  tendinous  fibres  having  al- 
ready conmienced  on  the  anterior  edge  of  the  muscle.  The  fleshy 
fibres  terminate  precisely  where  the  muscle  changes  its  direction 
to  pass  forward.  The  flat  tendon  by  which  they  are  succeeded  is 
at  first  narrow,  but  becomes  considerably  expanded,  to  be  inserted 
into  the  crest  of  the  tibia,  in  front  of  the  tendons  of  the  semi-ten- 
dinosus  and  gracilis  muscles,  with  which  it  is  united,  so  as  to 
form  what  is  called  the  patte  d'oie  (goose's  foot).  A  synovial 
membrane  separates  it  from  the  tendons  of  these  muscles.  A 
considerable  tendinous  expansion  is  given  off  from  its  lower  edge, 
and  contributes  to  form  the  inner  part  of  the  fascia  of  the  leg. 

Relations. — ^The  sartorius  is  the  most  superficial  muscle  in  the 
anterior  aspect  of  the  thigh ;  it  lies  beneath  the  femoral  fascia, 
and  covers  the  psoas  and  iliacus,  the  rectus,  the  vastus  internus, 
the  adductor  longus,  the  gracilis,  the  adductor  magnus,  and  the 
internal  lateral  ligament  of  the  knee-joint.  The  borders  of  this 
muscle  deserve  particular  attention,  because  incisions  for  ligature 
of  the  femoral  artery  must  be  made  along  them.  Its  most  important  relation,  indeed,  is 
with  the  femoral  artery  and  vein  ;  it  is  the  satellite  muscle  of  the  femoral  artery.  Thus, 
in  the  upper  third  of  the  thigh,  it  forms,  with  the  adductor  longus  and  femoral  arch,  an 
isosceles  triangle,  having  its  base  turned  upward,  and  the  femoral  artery  represents  a 
perpendicular  drawn  from  the  apex  to  the  base  of  the  triangle.  In  the  middle  third  of 
the  thigh,  the  artery  is  in  relation,  first,  with  the  inner  border,  then  with  the  posterior 
surface,  and,  lastly,  with  the  outer  border  of  the  muscle.  In  the  lower  third,  the  sarto- 
rius occupies  a  deep  groove,  formed  by  the  gracilis  and  vastus  internus  ;  from  the  latter 
muscle  it  is  separated  below  by  an  interval  containing  adipose  tissue,  of  which  circum- 
stance advantage  may  be  taken  in  the  application  of  issues.  It  also  covers  the  saphenus 
nerve  (a  deep  branch  of  the  anterior  crured),  which  emerges  from  beneath  its  anterior  bor- 
der, opposite  the  lowermost  point  of  insertion  of  the  adductor  magnus.  Near  the  knee- 
joint,  the  saphena  vein  is  in  relation  with  the  posterior  border  of  the  muscle. 

The  structure  of  the  sartorius  is  very  simple.  The  fleshy  and  tendinous  fibres  are  all 
parallel,  and  the  former  correspond  exactly  with  the  length  of  the  muscle. 

Action. — The  sartorius  flexes  the  leg  upon  the  thigh,  which  it  draws  inward,  so  as  to 
cross  one  leg  over  the  other.  When  this  movement  is  produced,  it  flexes  the  thigh  upon 
the  pelvis.  If  the  fixed  point  of  the  muscle  be  at  the  leg,  it  then  flexes  the  pelvis  upon 
the  thigh,  and  rotates  it,  so  that  the  anterior  surface  of  the  trunk  is  directed  to  the  op- 
posite side. 

The  Rectus  Femoris  and  Triceps  Extensor  Cruris,  or  the  Triceps  Femoralis. 

I  have  included  under  the  name  triceps  femoralis  the  two  muscles,  or,  rather,  the  two 
parts  of  the  same  muscle,  which  are  described  separately  in  most  anatomical  works. 
The  reasons  for  this  arrangement  will  be  understood  after  the  following  description  of 
the  muscle  : 

I  shall  consider  the  triceps  femoralis  as  composed  of  three  portions,  viz.,  a  middle  or 
long  portion,  the  rectus  femoris  of  authors ;  an  external  and  an  internal  portion,  which 
constitute  together  the  triceps  cruris  of  authors  ;  for  these  I  shall  retain  the  names  of 
vastus  internus  and  externus,  including  in  the  former  the  middle  portion  or  crureus,  prop- 
erly so  called,  of  most  anatomists. 

The  long  portion  of  the  triceps  femoralis,  or  the  rectus  femoris  (r,  fig.  126),  is  situated  in 
the  anterior  region  of  the  thigh,  extending  from  the  anterior  inferior  spinous  process  of 
the  ilium  to  the  patella  :  it  is  vertical  in  its  direction,  thick  and  broad  in  the  middle,  and 
narrowei  at  its  extremities  in..-;-r 


THE   RECTUS    FEMORIS   AND    TRICEPS    EXTENSOR    CRURIS.  273 

It  arises  by  a  very  strong  tendon  (r,  fig.  127),  which  embraces  the  anterior  inferior 
spinous  process  of  the  ihum,  and  is  proportioned  to  the  power  of  the  muscle.  This  ten- 
don receives  on  its  outer  side  another  flat  tendon,  arising  from  a  groove  upon  the  rim 
of  the  cotyloid  cavity,  and  following  its  curvature  ;  this  is  the  rejected  tendon,  which  is 
blended  with  and  strengthens  the  straight  tendon.  It  then  expands  into  a  broad  aponeu- 
rosis, the  outer  portion  of  which  is  very  thin  and  prolonged  over  the  anterior  surface  of 
the  muscle  as  far  as  the  middle,  while  the  inner  portion  is  very  thick,  and  penetrates 
into  its  substance  nearly  as  far  as  its  insertion.  The  fleshy  fibres  arise  from  the  poste- 
rior surface  and  edges,  and  also  from  the  anterior  surface  of  the  inner  portion  of  this 
aponeurosis  ;  they  all  pass  downward  and  backward,  the  internal  inward  and  the  exter- 
nal outward,  and  form  a  fleshy  belly,  which  increases  as  it  proceeds  downward,  and  then 
terminates  on  the  anterior  surface  of  a  broad,  thick,  and  shining  aponeurosis,  occupying 
the  lower  two  thirds  of  the  posterior  surface  of  the  muscle,  and  soon  becoming  contract- 
ed into  a  flat  tendon,  which  receives  upon  its  inner  edge  the  superficial  fibres  of  the 
vastus  intemus,  again  expands,  and  is  finally  blended  with  the  common  tendon  of  the 
two  vasti. 

Triceps  Femoris  of  Authors,  or  Vastus  Internus  and,  Externus. — This  is  a  voluminous 
mass  of  muscular  tissue,  situated  behind  the  preceding  muscle,  and  extending  from  the 
three  surfaces  of  the  shaft  of  the  femur  to  the  patella  and  tibia.  It  is  commonly  but  er- 
roneously considered  to  be  divided  above  into  three  heads,  which  are  described  under 
the  names  of  vastus  internus,  vastus  externus,  and  crureus.  I  have  searched  in  vain  for 
the  middle  portion,  but  have  never  been  able  to  find  more  than  two  separate  parts  :  one 
external,  very  large  and  superficial,  viz.,  the  vastus  externus;  the  other  internal,  anteri- 
or, and  even  external,  viz.,  the  vastus  internus ;  it  is  much  smaller  than  the  vastus  ex- 
ternus, and  is  partly  covered  by  it  and  by  the  rectus. 

The  external  portion,  or  vastus  externus  {s,  figs.  124  to  127).  This  is  the  largest  portion 
of  the  triceps  femoralis.  It  arises  from  a  projecting  border  or  horizontal  crest,  situated 
at  the  base  of  the  great  trochanter,  and  from  a  vertical  edge  in  front  of  that  trochanter, 
which  forms  a  continuation  of  its  anterior  border,  and  sometimes  presents  a  very  prom- 
inent tubercle  :  in  the  angle  formed  by  these  two  attachments  is  situated  tlie  tendon  of 
the  glutseus  medius.  It  also  arises  along  a  line  running  from  the  great  trochanter  to  the 
linea  aspera,  and  from  the  whole  extent  of  the  external  lip  of  the  linea  aspera  itself 
All  the  preceding  origins  are  effected  by  means  of  a  broad  aponeurosis  which  covers  the 
superior  three  fourths  of  the  muscle,  and  from  the  deep  surface  of  which  almost  all  the 
fleshy  fibres  proceed.  Lastly,  some  of  these  arise  from  the  tendon  of  the  gluta?us  max- 
imus,  and  from  the  tendinous  septum  intervening  between  the  vastus  externus  and  the 
short  head  of  the  biceps.  From  these  origins  the  fleshy  fibres  proceed,  some  vertically 
downward,  the  others  somewhat  obliquely  downward  and  forward,  the  lowest  being  the 
shortest  and  the  most  oblique  ;  they  form  a  large  bundle,  which  partially  covers  the  an- 
terior portion  of  the  vastus  intemus,  but  is  separated  from  it  by  vessels,  nerves,  and  cel- 
lular tissue.  After  a  course  of  variable  length,  some  of  the  fleshy  fibres  are  attached  to 
the  deep,  but  the  greater  number  to  the  superficial  surface  of  another  equally  strong  apo- 
neurosis :  this  becomes  thickened  and  contracted  into  a  flat  tendon,  which  is  sometimes 
divided  into  thick  parallel  bands,  emerges  from  the  fleshy  fibres  at  the  external  margin 
of  the  rectus,  and  is  inserted  into  the  outer  half  of  the  upper  border  of  the  patella,  being 
blended  on  the  inner  side  with  the  rectus  and  the  vastus  intemus.  The  lower  fleshy 
fibres  which  arise  from  the  inter-muscular  septum  are  attached  directly  to  the  outer  bor- 
der of  the  patella.* 

The  internal  or  anterior  portion,  vastus  internus  {t  and  u,fig.  127),  is  much  smaller  than 
the  external,  and  surrounds  the  femur.  Its  inner  portion  lies  immediately  under  the  fas- 
cia, and  is  the  only  part  which  is  generally  described  as  the  vastus  internus  {t,figs.  126, 127). 
Its  anterior  portion  is  covered  by  the  rectus,  or  long  portion,  and  is  usually  called  the 
crureus  (cmralis,  Alb.,  u,fig.  127).  Its  outer  portion  is  covered  by  the  vastus  externus, 
with  which  many  of  its  fibres  are  blended  ;  but  they  may  always  be  separated  by  cutting 
along  the  outer  margin'  of  the  middle  aponeurosis.  Thus  defined,  the  vastus  internus 
arises  from  a  rough  oblique  line,  extending  from  the  front  of  the  neck  of  the  femur  to  the 
linea  aspera,  and  from  the  internal  lip  of  the  linea  aspera  itself,  in  front  of  the  adductor 
muscles  :  both  of  these  origins  are  effected  by  means  of  an  aponeurosis,  which  is  weaker 
and  smaller  than  that  of  the  vastus  externus,  and  is  blended  with  that  of  the  adductors, 
concurring  w  ith  it  in  the  formation  of  a  canal  for  the  femoral  artery.  It  also  arises  from 
almost  the  whole  of  the  internal,  anterior,  and  external  surfaces,  and  from  the  two  ante- 
rior borders  of  the  femur ;  lastly,  the  lower  fibres  arise  from  the  internal  inter-muscular 
septum.  From  these  different  origins  the  fleshy  fibres  pass  in  various  directions ;  the 
external  inward,  the  middle  vertically,  and  the  internal,  which  are  the  most  numerous, 
downward,  forward,  and  outward ;  they  thus  form  a  fleshy  belly,  thicker  below  and  with- 
in than  above  and  without,  and  are  successively  attached  to  both  surfaces,  and  espe- 
cially to  the  posterior  surface  of  a  broad  aponeurosis,  which  is  covered  by  the  tendon  of 

*  Tke  anterior  border  of  this  tendon  is  free,  and  perfectly  distinct  from  the  tendon  of  the  rectus,  which  is 
lined  by  it ;  and  also  from  the  expanded  tendon  of  the  vastus  internus. 

Mm 


2T4  MYOLOGY. 

the  vastus  externus,  but  can  be  easily  separated  from  it.  The  uiner  fibres  are  attached 
to  the  anterior  surface  of  the  aponeurosis,  and  terminate  very  regularly  opposite  a  verti- 
cal line,  running  parallel  to  the  inner  margin  of  the  rectus  femoris. 

The  aponeurosis  extends  over  the  anterior  surface  of  the  middle  portion  of  the  mus- 
cle, which  lies  behind  the  rectus  :  this  fact  has,  doubtless,  given  rise  to  its  division  into 
two  parts,  viz.,  a  middle,  or  the  crureus,  and  an  internal,  called  the  vastus  internus.  The 
superficial  layer  of  the  interna!  fleshy  fibres  is  attached  below  to  the  inner  margin  of  the 
rectus,  or  long  portion  of  the  triceps  femoralis  :  the  lowest  of  these  fibres,  which  arise 
from  the  inner  and  inferior  bifurcation  of  the  linea  aspera,  and  from  the  corresponding 
inter-muscular  septum,  are  almost  horizontal,  and  accompany  the  tendon  as  far  as  its  in- 
sertion into  the  inner  border  of  the  patella.  Lastly,  the  terminating  aponeurosis  is  pro- 
longed inward  to  the  internal  tuberosity  of  the  tibia,  below  which  it  is  inserted,  being 
covered  by  the  tendons  of  the  semi-tendinosus,  semi-membranosus,  and  gracilis  muscles, 
on  the  inner  side  of  the  internal  lateral  ligament  of  the  knee.  This  very  strong  aponeu- 
rotic insertion  represents  the  fascia  lata  on  this  aspect  of  the  limb,  and  forms  an  acces- 
sory internal  lateral  ligament. 

From  the  above  description,  it  follows  that  the  triceps  femoralis  is  composed  of  three 
muscles  and  three  tendons,  super-imposed  upon  each  other,  viz.,  the  rectus  femoris,  the 
vastus  externus,  and  the  vastus  internus. 

Relations. — The  long  portion  of  the  triceps,  or  the  rectus  femoris,  is  covered  by  the 
fascia  lata  in  its  lower  three  fourths.  Its  upper  part  is  covered  by  the  sartorius,  by  the 
anterior  fibres  of  the  glutajus  medius,  and  by  the  psoas  and  iliacus.  It  covers  the  hip- 
joint,  the  anterior  circumflex  vessels,  and  the  two  vasti  muscles.  The  vasti  surround 
the  femur  as  in  a  muscular  sheath,  and  have  relations  with  all  the  muscles  of  the  thigh. 
They  are  superficial  in  a  great  part  of  their  extent :  in  front,  they  are  in  relation  with 
the  psoas  and  iliacus,  the  rectus  femoris,  and  the  sartorius,  and  they  lie  immediately 
under  the  fascia,  in  the  triangular  spaces  left  between  these  muscles  :  behind,  they  are 
in  relation  with  the  biceps  and  semi-membranosus ;  on  the  inside,  with  the  adductors, 
with  the  femoral  artery,  the  sheath  of  which  the  vastus  internus  contributes  to  form, 
and  with  the  sartorius ;  on  the  outside,  with  the  glutaeus  maximus,  which  glides  over 
the  upper  end  of  the  vastus  externus,  and  is  separated  from  it  by  a  synovial  bursa ;  and, 
lastly,  with  the  tensor  vaginae  femoris,  and  the  fascia  lata.  It  is  necessary  to  allude 
here  to  a  small  fleshy  bundle,  formed  by  the  deepest  and  lowest  fibres  of  the  vastus  in- 
ternus, which  is  always  distinct  from  the  rest  of  the  muscle,  and  is  inserted  into  the  up- 
per part  of  the  synovial  membrane  of  the  knee.  This  bundle  has  been  regarded  by  Wins- 
low  as  an  articular  muscle,  intended  to  prevent  the  synovial  membrane  from  being 
pinched  between  the  surfaces  of  the  joint. 

Action. — This  muscle  extends  the  leg  upon  the  thigh  ;  its  action  is  facilitated  by  the 
existence  of  the  patella,  which  serves  to  increase  the  angle  of  insertion,  and  which  we 
have  described  as  a  sesamoid  bone,  developed  in  the  substance  of  the  tendon.  We  must, 
therefore,  regard  the  triceps  as  inserted  into  the  anterior  tuberosity  of  the  tibia,  or,  rath- 
er, into  tiie  lower  part  of  that  tuberosity.  It  should  be  observed,  that  the  tendon  is  in- 
serted into  the  patella,  in  front  of  its  base,  and  not  into  the  base  itself,  in  the  same  man- 
ner as  the  ligameutum  patellae  is  attached  to  the  anterior  surface  of  that  bone,  and  not 
to  the  rough  mark  on  its  posterior  surface  :  this  important  arrangement  increases  the 
angle  at  which  the  moving  power  operates.  The  triceps  femoralis  is  the  most  powerful 
muscle  in  the  body,  no  other  having  such  large  surfaces  of  origin,  and,  consequently,  so 
great  a  number  of  fibres.  By  itself  it  supports,  in  a  state  of  equilibrium,  tlie  entire 
weight  of  the  body  in  standing,  and  may  be  adduced  as  a  striking  example  of  the  pre- 
dominance of  the  extensors  over  the  flexors  ;  it  is  also  this  muscle  which  raises  the 
whole  trunk  in  progression  and  in  the  act  of  leaping.  We  cannot,  therefore,  be  astonish- 
ed at  rupture  of  the  patella,  of  its  ligament,  or  of  the  common  tendon,  during  a  violent 
contraction  of  this  muscle,  notwithstanding  its  disadvantageous  insertion  so  near  to  the 
fulcrum.  The  rectus  necessarily  acts  with  the  two  vasti,  but  it  can  also  flex  the  thigh 
upon  the  pelvis.  The  somewhat  oblique  direction  of  the  tendon  of  the  triceps  down- 
ward and  iawar^,  and  of  the  ligameutum  patelljff  downward  and  outward,  so  that  Siey 
form  an  obtuse  angle,  open  to  the  outside  {see  Jig.  126),  and  more  especially Jliejjjfedom- 
inance  of  the  vastus  externus  over  the  vastus  internus,  sufficiently  account  for  the  oc- 
currence of  luxation  of  the  patella>Qulw.aj:d,taiid  (dr  the  impossibility  of  its  beiifig  dislo- 
cated inward. 

When  the  patella  is  forced  inward  by  external  violence,  the  contraction  of  the  vastus 
externus  draws  it  back  into  its  original  position  :  on  the  other  hand,  the  action  of  this 
muscle  has  a  tendency  to  displace  it  outward ;  and  when  this  is  accomplished,  the  same 
muscle  keeps  it  in  its  abnormal  position.  Luxations  of  the  patella,  therefore,  if  not  al- 
together irreducible,  can  only  be  temporarily  replaced  ;  whenever  the  hand  ceases  to  re- 
tain tlie  bone  in  its  proper  place,  the  contraction  of  this  muscle  again  dislocates  it.  Pro- 
fessor Ant.  Dubois  has  informed  me  of  an  individual  whose  knees  were  bent  very  much 
inward,  who  could  not  contract  the  triceps  femoralis  with  any  force  without  dislocating 
the  patella  outward. 


THK    GRACILIS,    ETC. 


iM 


Internal  Region  of  the  Thigh. 

The  muscles  of  the  internal  region  of  the  thigh  are  the  gracilis  and  the  adductors, 
among  which  I  include  the  pectineus. 

The  Gracilis. 

The  gracilis  (le  grele  interne,  ou  droit  interne,  Winslow,  v,figs.  124,  125,  126)  is  a  long, 
straight,  and  slender  muscle,  and  the  most  superficial  of  those  situated  on  the  inside  of 
.he  thigh. 

Attachments. — It  arises  from  the  symphysis  pubis,  between  the  pubic  spine  and  the 
ascending  ramus  of  the  ischium,  and  is  inserted  into  the  spine  of  the  tibia.  It  arises  by 
some  long,  shining,  and  parallel  tendinous  fibres,  which  bind  down  a  perpendicular  fibrous 
bundle  that  lies  on  the  inner  side  of  the  line  of  attachment.  The  fleshy  fibres  succeed- 
ing to  these  are  at  first  parallel,  and  "form  a  broad,  thin  bundle  ;  they  then  converge  to- 
wards each  other,  so  that  the  entire  muscle  resembles  a  much  elongated  isosceles  tri- 
angle. It  is  rounded  below,  and  terminates  in  a  long,  thin  tendon,  which  runs  for  a  con- 
siderable distance  upon  its  posterior  border,  and  receives  all  the  fleshy  fibres  in  succes- 
sion. This  tendon  becomes  free  immediately  above  the  knee-joint,  is  then  situated  be- 
hind the  internal  condyle  of  the  femur,  turns  round  this  process  and  the  corresponding 
tuberosity  of  the  tibia,  and  is  inserted  into  the  spine  of  the  last-mentioned  bone,  behind 
the  tendon  of  the  sartorius,  and  above  that  of  the  semi-tendinosus,  with  both  of  which  it 
is  united  so  as  to  form  the  trifid  aponeurotic  interlacement,  denominated  la  patte  d'aie 
(goose's  foot). 

Relations. — The  gracilis  is  covered  by  the  femoral  fascia,  and  slightly  by  the  sartorius 
at  its  lower  part :  it  covers  the  three  adductors,  the  inside  of  the  knee-joint,  and  the  in- 
ternal lateral  ligament,  from  which  it  is  separated  by  a  synovial  bursa  common  to  it  and 
the  semi-tendinosus  :  the  vena  saphena  interna  crosses  the  inner  surface  of  this  muscle 
obliquely,  near  its  lower  extremity. 

Action. — It  flexes  the  leg,  and  carries  it  slightly  inward,  at  the  same  time,  by  means  of 
its  reflection  round  the  knee  ;  in  this  part  of  its  action  it  assists  the  sartorius ;  it  also  ad- 
ducts  the  thigh.     In  the  position  of  standing,  its  movable  point  is  at  the  pelvis. 

The  Mductor  Muscles  of  the  Thigh. 

There  are  three  muscles  on  the  inner  aspect  of  the  thigh  which  are  called  adductors ; 
with  these  the  older  anatomists  were  acquainted  under  the  collective  name  of  the  triceps 
adductor.  Modern  viTiters,  however,  describe  them  either  in  the  order  of  their  super- 
imposition,  as  the  fo-st,  seco7id,  and  third  (Boyer) ;  or  in  the  order  of  their  size,  as  the  mid- 
dle, small,  and  great  adductors  (Bichat).  These  vague  denominations  are  the  source  of 
much  confusion,  for  the  one  which  occupies  the  middle  place  as  regards  size  is  the  first 
as  regards  its  position.  I  have  therefore  thought  it  right  to  modify  these  names,  and 
have,  at  the  same  time,  included  the  pectineus  among  the  adductor  muscles.  I  consider, 
therefore,  that  there  are  four  adductors,  which  I  shall  divide  into  superficial  and  deep ; 
the  two  superficial  are  the  pectineus  and  the  first  or  long  adductor ;  these  I  shall  term 
the  first  and  second. 

Superficial  Adductors. — The  two  deep  are  the  short  and  the  great  adductors,  which  I 
shall  denominate  the  small  deep  adductor  and  the  great  deep  adductor.  Strictly  speaking,  we 
could  only  admit  the  existence  of  two  adductors,  one  superficial,  the  other  deep ;  and  this 
mode  of  division  would  perhaps  be  preferable. 

Dissection. — This  is  common  to  all  the  adductors.  Abduct  the  thigh  so  as  to  render 
these  muscles  tense.  Make  an  incision  through  the  integuments  from  the  middle  of  the 
femoral  arch  to  the  patella,  and  a  semicircular  incision  at  either  end  of  this  ;  preserve 
the  vessels  and  nerves,  in  order  to  examine  their  relations  ;  tie  and  cut  across  the  vena 
sephena  where  it  enters  the  femoral  vein ;  divide  the  fascia  lata,  and  dissect  the  mus- 
cles, which  will  then  be  brought  into  view. 

The  First  Superficial  Adductor,  or  Pectineus. 

Tiie  pectineus  {pecten,  the  pubes)  is  a  square  muscle  {w,  fig.  126)  situated  at  the  upper 
anterior  and  inner  aspect  of  the  thigh,  on  the  inner  side  of  the  psoas  and  iliacus  (c). 

Attachments. — It  arises  (w,  fig.  127)  from  the  spine  and  crest  of  the  pubes,  from  the  trian- 
gular surface  in  front  of  this  crest,  and  from  the  lower  surface  of  a  very  strong  tendinous 
and  arched  prolongation  of  Gimbernat's  ligament,  which  is  attached  to  the  crest  of  the  pu- 
bes, and  is  continuous  with  the  fascia  covering  the  muscle.  It  is  inserted  (w,  fig-  127) 
below  the  lesser  trochanter,  into  the  ridge  extending  from  that  process  to  the  linea  as- 
pera.  With  the  exception  of  the  spine  of  the  pubes,  where  there  are  always  some  well- 
marked  tendinous  attachments,  the  fleshy  fibres  commence  directly  from  the  several  ori- 
gins :  they  proceed  downward,  backward,  and  outward,  and  constitute  a  bundle,  which  is 
at  first  flattened  from  before  backward,  and  afterward  from  without  inward .-  the  fibres  of 
this  after  a  short  course  converge,  and  are  inserted  into  the  internal  bifurcation  of  the 
linea  aspera,  in  part  directly,  and  partly  through  the  medium  of  an  aponeurosis  which  oc- 
cupies the  anterior  surface  of  the  muscle. 


MYOLOGY. 


Tig.  127. 


Relations. — The  pectineus  is  covered  by  the  deep  layer  of 
the  femoral  fascia,  and  by  the  femoral  vessels.  It  covers  the 
capsular  ligament  of  the  joint,  the  small  deep  adductor,  and 
the  obturator  externus,  from  which  it  is  separated  by  the  ob- 
turator vessels  and  nerves.  Its  outer  border  is  parallel  with 
the  inner  border  of  the  conjoined  portions  of  the  psoas  and 
iliacus,  and  is  separated  from  them  by  a  cellular  interval,  over 
which  the  femoral  artery  passes  ;  so  that,  were  it  not  for  the 
projection  of  this  outer  border,  this  vessel  would  be  in  imme- 
diate contact  with  the  bone.  Its  inner  border  is  in  relation 
with  the  second  superficial  adductor,  and  is  sometimes  blend- 
ed with  it,  except  below,  where  it  is  separated  by  an  interval 
in  which  the  small  deep  adductor  may  be  seen.  It  has  an  im- 
portant relation  with  the  anterior  orifice  of  the  sub-pubic  canal, 
which  corresponds  with  the  posterior  surface  of  the  muscle. 
When  hernial  protrusions,  therefore,  take  place  at  the  fora- 
men ovale,  the  displaced  parts  are  always  covered  by  the  pec- 
tineus muscle. 

The  Second  Superficial  Adductor^  or  Mductor 
Longus. 
The  adductor  longus  of  Albinus  (le  premier  adducteur,  Ba- 
yer; le  moyen  adducteur,  Bichat,  x,fig.  126)  is  a  flat,  triangu- 
lar muscle,  situated  on  the  same  plane  as  the  pectineus,  of 
which  it  seems  to  be  a  continuation,  and  with  which  it  is  often 
blended  above.  For  this  reason,  Vesalius  made  of  these  two 
muscles  his  eighth  pair  of  muscles  of  the  thigh,  under  the 
name  of  pars  octava  femur  moventium.  It  is  certain  that  there 
is  a  sort  of  consolidation  between  these  two  muscles,  and  that 
a  small  pectineus  is  always  observed  in  conjunction  with  a 
large  adductor  longus. 

Attachments. — It  arises  {x,  Jig.  127)  from  the  spine  of  the 
pubes,  and  is  inserted  {x)  into  the  middle  third  of  the  linea  as- 
pera  of  the  femur.  Its  origin  consists  of  a  narrow,  flat  ten- 
don, which  expands  anteriorly,  and  gives  origin  to  a  thick  and 
broad  fleshy  belly ;  this  passes  downward,  backward,  and  out- 
ward, and  is  inserted  into  the  middle  third  of  the  linea  aspera 
of  the  femur,  between  the  triceps  femoralis  in  front,  and  the  great  deep  adductor  behind  : 
with  the  latter  of  these  muscles  it  becomes  blended  at  its  insertions.  It  is  attached  to 
the  bone  by  means  of  two  tendinous  layers,  between  which  the  fleshy  fibres  are  receiv- 
ed. A  number  of  foramina,  intended  for  the  perforating  arteries,  are  observed  in  the  neigh- 
bourhood of  this  attachment. 

Relations. — Its  upper  part  lies  immediately  under  the  fascia,  and  it  becomes  gradually 
deeper  as  it  passes  downward.  It  is  in  relation  with  the  sartorius,  from  which  it  is  sep- 
arated by  the  femoral  artery  and  veins.  This  relation  is  one  of  great  importance,  as  I 
shall  hereafter  have  occasion  to  point  out. 

The  Small  Deep  Adductor,  or  Adductor  Brevis. 

The  adductor  brevis  o{  Albinus  (le  seconde  of  Boyer ;  le  petit  of  Bichat,  y,fig.  127)  is 
of  the  same  form  as  the  preceding  muscle,  and  is  the  second  in  the  order  of  super-im- 
position, but  the  smallest  in  size.  It  arises  below  the  spine  of  the  pubes  on  the  outer 
side  of  the  gracilis  and  the  inner  side  of  the  obturator  externus,  from  a  variable  extent 
of  surface.  The  fibres  proceed  outward,  downward,  and  a  little  backward,  and  form  a 
thick  bundle,  at  first  flattened  from  within  outward,  and  then  from  before  backward, 
which  increases  in  breadth,  and  terminates  at  the  middle  of  the  linea  aspera  of  the  femur, 
in  front  of  the  great  deep  adductor,  and  behind  the  two  superficial  adductors,  with  which 
it  is  blended  at  its  insertion. 

Relations. — It  is  covered  by  the  superficial  adductors,  and  it  covers  the  great  deep  ad- 
ductor, or  adductor  magnus.  Its  outer  border  has  a  relation  with  the  obturator  externus, 
and  the  conjoined  psoas  and  iliacus  muscles ;  its  inner  border  is  at  first  in  contact  with 
the  gracilis,  and  is  then  applied  to  the  adductor  magnus,  from  which  it  is  sometimes 
difficult  to  separate  it. 

The  Great  Deep  Adductor,  or  Adductor  Magnus. 
Dissection. — In  order  to  obtain  a  good  view  of  this  muscle,  it  is  not  suflicient  to  study 
its  anterior  surface  only,  which  is  exposed  after  the  preceding  muscles  have  been  divi- 
ded ;  its  posterior  surface  must  also  be  examined  ;  and  for  this  purpose  it  is  necessary 
to  remove  the  three  muscles  of  the  posterior  region  of  the  thigh,  viz.,  the  biceps,  the 
semi-tendinosus,  and  the  semi-membranosus. 


THE    ADDUCTOR   MAGNUS,  ETC.  277 

The  adductor  magnus  of  Alhimis  (le  troisi^me  of  Boyer ;  le  grand  of  Bir.hat,  z,  z',  figs. 
124  to  127)  is  a  very  large,  triangular  muscle,  extremely  thick  internally,  where  it  con- 
stitutes almost  the  entire  substance  of  the  inside  of  the  thigh  {fig.  127).  It  arises  from 
the  whole  extent  of  the  ascending  ramus  of  the  ischium,  from  a  small  part  of  the  de- 
scending ramus  of  the  pubes,  and  from  the  apex,  i.  c,  the  lowest  portion,  of  the  tuberos- 
ity of  the  ischium.  It  is  inserted  into  the  whole  extent  of  the  interval  between  the  two 
lips  of  the  linea  aspera,  and  into  a  very  prominent  tubercle  upon  the  inner  condyle  of  the 
femur,  above  the  depression  for  the  insertion  of  the  tendon  of  the  inner  head  of  the  gas- 
trocnemius. Its  origins,  especially  those  from  the  ischium,  which  are  the  principal,  can 
only  be  seen  on  the  posterior  surface  of  the  muscle  (see  fig.  125).  They  consist  of  ten- 
dinous bundles,  giving  origin  immediately  to  fleshy  fibres,  which  form  an  extremely  thick 
mass,  directed  downward  and  outward,  and  presenting  coarse  bundles,  almost  as  large 
and  as  easily  separable  as  those  of  the  glutasus  maximus.  The  muscle  soon  divides 
into  two  portions,  or,  rather,  into  two  distinct  muscles,  an  internal  and  an  external. 

The  internal  portion  {z,figs.  125,  127)  forms  the  inner  border  of  the  adductor  magnus, 
the  original  course  of  which  it  follows.  About  the  lower  third  of  the  thigh,  its  fibres 
are  received  into  a  tendinous  semi-cone,  open  on  the  outside,  and  terminating  in  a  shi- 
ning tendon,  which  is  inserted  into  a  well-marked  tubercle  on  the  upper  and  back  part  of 
the  internal  condyle  of  the  femur.  Throughout  its  whole  course,  this  tendon  lies  close 
to  the  aponeurosis  of  the  vastus  internus. 

The  external  portion  (z',^^.  125),  abandoning  the  primitive  direction  of  the  muscle,  is 
directed  outward,  and  separates  into  thick  bundles,  which  are  inserted  into  the  whole 
extent  of  the  interval  between  the  lips  of  the  linea  aspera  by  means  of  a  very  large 
aponeurosis,  which  is  intimately  united  to  the  tendons  of  the  other  adductors,  and  forms 
a  series  of  arches  (see  fig.  125)  for  the  passage  of  the  perforating  arteries. 

These  two  divisions  of  the  adductor  magnus  are  separated  below  by  the  femoral  ar- 
tery and  veins  and  their  sheath,  and  are  generally  distinct  for  a  considerable  extent,  and 
sometimes  entirely  so.  I  have  met  with  a  case  of  this  kind.  That  portion  of  the  mus- 
cle which  was  inserted  into  the  internal  condyle  arose  entirely  from  the  apex  of  the  tu- 
berosity of  the  ischium ;  while  the  origin  of  that  portion  which  was  attached  to  the  linea 
aspera  took  place  from  a  prominence  situated  on  the  external  side  of  that  tuberosity, 
and  projecting  outward  from  it,  and  also  from  the  ascending  ramus  of  the  ischium,  and 
the  descending  ramus  of  the  pubes,  externally  to  the  gracilis  muscle.  The  superior 
fibres  {fig.  125)  are  horizontal,  and,  forming  a  distinct,  and,  as  it  were,  a  radiated  bundle, 
turn  in  front  of  the  succeeding  fibres,  and  are  inserted  into  the  line  leading  from  the 
great  trochanter  to  the  linea  aspera,  internally  to  the  glutaeus  maximus. 

Relations. — The  adductor  magnus  is  covered  by  the  superficial  adductors  and  by  the 
small  deep  adductor :  it  covers  the  semi-tendinosus,  the  biceps,  the  semi-membranosus, 
and  the  glutaeus  maximus.  Its  inner  border  is  bounded  by  the  gracilis  above,  and  by  the 
sartorius  below:  its  upper  border  is  in  contact  with  the  obturator  externus  ie,fig.  127) 
on  the  inside,  and  with  the  quadratus  femoris  (i,  fig.  125)  more  externally.  Its  most 
important  relation  is  that  with  the  femoral  artery  and  vein,  which  pass  through  it  before 
reaching  the  popliteal  space.  At  the  place  where  this  periforation  occurs  we  observe  a 
tendinous  arch,  or,  rather,  canal,  into  which  the  fleshy  fibres  are  inserted ;  and  so,  also, 
where  the  perforating  arteries  pass  through  this  muscle. 

Action  of  the  Adductor  Muscles. — ^The  muscles  we  have  just  described  are  both  flexors 
and  rotators  outward ;  but  their  principal  office,  as  their  name  indicates,  is  to  perform 
adduction,  a  very  energetic  movement,  as  might  be  anticipated  from  the  strength  of  the 
muscles  concerned  in  its  production.  We  have  seen,  indeed,  that  the  line  of  origin  ex- 
tends from  the  ilio-pectineal  eminence  as  far  as  and  including  the  tuberosity  of  the  ischi- 
um, and  that  the  insertions  occupy  the  entire  length  of  the  linea  aspera,  the  two  branch- 
es of  its  superior  bifurcation,  and  the  inner  condyle  of  the  femur.  These  muscles  are 
powerfully  exerted  during  equestrian  exercise ;  it  is  by  their  means  that  the  horse  is 
firmly  grasped  between  the  knees.  The  two  superficial  adductors  and  the  adductor  bre- 
vis  are  also  flexors,  because  their  insertions  are  posterior  to  their  origins.  All  the  ad- 
ductors are,  as  it  were,  rolled  around  the  femur  during  rotation  inward. 


MUSCLES  OF  THE  LEG. 

The  Tibialis  Anticus. — Extensor  Communis  Digitorum. — Extensor  Proprius  Pollicis. — Pe- 
roneus  Longus  and  Brevis. — Gastrocnemius,  Plantarus,  and  Soleus. — Popliteus. — Titia- 
lis  Posticus. — Flexor  Longus  Pollicis. 

The  muscles  of  the  leg  may  be  divided  into  those  of  the  anterior,  those  of  the  exter- 
nal, and  those  of  the  posterior  regions. 

Muscles  of  the  Anterior  Region  of  the  Leg. 
The  muscles  of  the  anterior  region  of  the  leg  are  the  tibialis,  the  extensor  communis 
digitorum.  and  the  extensor  proprius  pollicis  pedis.     The  anterior  peroneus,  or  peroneus 


ms 


MYOLOGY. 


tertius,  wlien  it  exists,  is  nothing  more  than  an  accessory  fasciculus  of  the  extensor 
communis. 

The  Tibialis  Anticus. 
Dissection. — ^Make  a  vertical  incision  through  the  skin  from  the  anterior  tuberosity  of 


Fig.l^ 


the  tibia  to  the  middle  of  the  inner  border  of  the  foot ;  dissect 
back  the  two  flaps  of  skin,  and  expose  the  fascia  of  the  leg  ;  di- 
vide this  fascia  vertically,  commencing  from  the  middle  of  the 
leg,  and  terminating  at  the  lower  end  of  the  tibia,  taking  care  to 
preserve  the  annular  ligament ;  prolong  the  dissection  and  sep- 
aration of  the  fascia  as  far  upward  as  possible ;  lastly,  remove 
the  fascia  on  the  dorsum  of  the  foot,  which  covers  inferiorly  the 
tendon  of  the  tibialis  anticus. 

The  tibialis  anticus  {a,  fig.  128)  is  a  long,  thick,  prismatic,  and 
triangular  muscle,  placed  superficially  along  the  outer  side  of  the 
tibia. 

Attachments. — It  arises  from  the  crest  which  bounds  the  ante- 
rior tuberosity  of  the  tibia  on  the  outside,  and  from  the  tubercle 
terminating  this  crest  above ;  from  the  external  tuberosity  of  the 
tibia,  and  the  superior  two  thirds  of  its  external  surface,  which 
presents  a  depression  proportioned  to  the  strength  of  the  muscle  ; 
from  all  that  portion  of  the  interosseous  ligament  situated  to  the 
inner  side  of  the  anterior  tibial  vessels  and  nerves ;  from  the 
deep  surface  of  the  fascia  of  the  leg ;  and,  lastly,  from  a  tendi- 
nous septum  intervening  between  this  muscle  and  the  extensor 
communis  digitorum.  It  is  inserted  into  the  tubercle  on  the  first 
or  internal  cuneiform  bone,  and  sends  oflT  a  tendinous  expansion 
to  the  first  metatarsal  bone. 

It  arises  from  the  internal  surface  of  an  osteo-fibrous  quadran- 
gular pyramid  formed  by  the  tibia,  the  fascia  of  the  leg,  the  inter- 
osseous ligament,  and  the  inter-muscular  septum ;  from  these 
points  the  fleshy  fibres  proceed  vertically  downward,  and  termi- 
nate around  a  tendon  which  commences  in  the  substance  of  the 
muscle  above  its  middle  third ;  the  anterior  fibres  cease  at  the 
lower  third  of  the  muscle,  the  posterior  accompany  the  tendon 
to  the  point  where  it  passes  under  the  dorsal  ligament  of  tlie  in- 
step (seen  in  fig.  128).  As  soon  as  the  tendon  appears  on  the 
anterior  border  of  the  muscle,  it  is  deflected  forward  in  a  similar 
manner  to  the  external  surface  of  the  tibia,  and  follows  the  same 
oblique  course,  after  having  left  the  common  sheath  of  all  the 
muscles  of  the  anterior  region  of  the  leg.  Another  sheath,  which 
is  nothing  more  than  the  condensed  dorsal  fascia  of  the  foot,  re- 
ceives the  tendon  at  the  point  where  it  passes  vertically  downward,  to  be  inserted  into 
the  tubercle  of  the  first  cuneiform  bone. 

Relations. — The  tibialis  anticus  is  covered  by  the  fascia  of  the  leg  asad  the  dorsal  fascia 
of  the  foot ;  on  the  inside  it  is  in  relation  with  the  external  surface  of  the  tibia ;  on  the 
outside,  at  first  with  the  extensor  communis  digitorum,  and  then  with  the  extensor  pro- 
prius  pollicis,  from  which  it  is  separated  behind  by  the  anterior  tibial  vessels  and  nerves. 
Action. — It  flexes  the  foot  upon  the  leg  ;  and,  from  tlie  obliquity  of  its  tendon,  it  raises 
the  internal  border  of  the  foot,  and,  consequently,  produces  that  sort  of  rotation  inward 
at  the  articulation  of  the  two  rows  of  the  tarsus  which  we  have  already  alluded  to.  It 
tends,  also,  to  adduct  the  ankle-joint,  and  is,  consequently,  opposed  to  dislocation  out- 
ward. The  absence  of  a  proper  sheath  for  this  muscle  explains  the  considerable  pro- 
jection formed  by  its  tendon  during  contraction,  which  may  serve  as  a  guide  to  the  pre- 
liminary incisions  in  ligature  of  the  dorsal  artery  of  the  foot.  Spigelius  called  this  mus- 
cle the  musculus  catencE,  because  fetters  applied  around  the  ankles  of  criminals  press 
chiefly  upon  the  projection  formed  by  its  tendon. 

The  Extensor  Longus  Digitorum  Pedis,  and  the  Peroneus  Tertius  vel  Anticus. 

Dissection. — Remove  the  fascia  of  the  leg  and  the  dorsal  fascia  of  the  foot. 

This  is  an  elongated,  semi-penniforra,  and  reflected  muscle  {b  c,  fig.  128),  flattened 
from  within  outward,  single  above,  and  divided  into  four  or  five  tendons  below. 

Attachments. — It  arises  from  the  external  tuberosity  of  the  tibia,  on  the  outer  side  of 
the  tibialis  anticus  ;  from  the  whole  of  the  internal  surface  of  the  fibula  in  front  of  the 
interosseous  ligament,  and  slightly  from  that  ligament ;  from  the  upper  part  of  the  fascia 
of  the  leg,  and  from  the  tendinous  septa  interposed  between  this  muscle  and  the  tibialis 
anticus  within,  and  the  peroneus  longus  and  brevis  without.  It  is  inserted  into  the  sec- 
ond and  third  phalanges  of  the  last  four  toes. 

From  these  numerous  origins  the  fleshy  fibres  proceed  in  different  directions ;  the  su- 


THE    EXTENSOR   PEOPRIUS    POLLICIS.  "^9 

perior  vertically  downward,  the  rest  obliquely  downward  and  forward,  the  lowest  being 
the  most  oblique  ;  they  all  terminate  around  a  tendon,  which  appears  upon  the  anterior 
border  of  the  muscle  below  the  upper  third  of  the  leg.  This  tendon  soon  divides  into 
two  portions :  one  internal,  and  itself  subdivided  into  three  tendons  for  the  second,  third, 
and  fourth  toes  ;  the  other  external,  and  generally  split  into  two  tendons,  one  of  which 
is  intended  for  the  fifth  toe,  while  the  other  is  fixed  to  the  posterior  extremity  of  the  cor- 
responding metatarsal  bone.  This  last  subdivision  is  often  wanting :  it  is  but  imperfect- 
ly separated  from  the  fasciculus  belonging  to  the  fifth  toe,  to  which  it  almost  edways 
sends  off  an  accessory  tendon  :  it  has  been  generally  described  as  a  separate  muscle, 
under  the  name  of  the  peroneus  tertius  or  anticus  {c,Jig.  128).  I  have  thought  it  right, 
however,  to  connect  this  muscle  with  the  extensor  longus  digitorum  (i),  from  which  it 
can  be  so  imperfectly  separated  that  it  has  been  designated  by  Cowper,  pars  extensoris 
digitorum  pedis  longi ;  and  by  Morgagni,  quintus  tendo  extensoris  longi  digitormn  pedis. 

The  extensor  communis  is  directed  vertically  as  far  as  the  ankle-joint,  where  it  enters 
a  sheath  conmion  to  it  and  the  flexor  proprius  poUicis,  is  next  reflected  under  this  sheath, 
becomes  horizontal,  passes  obliquely  inward  and  opposite  the  tarsus,  is  received  into  a 
much  stronger  proper  sheath,  after  leaving  which  the  five  tendons  separate  so  as  to  cov- 
er the  dorsd  surface  of  the  metatarsal  bone  of  the  toes,  to  which  they  correspond.  In 
this  course  they  cross  the  extensor  brevis  digitorum  at  a  very  acute  angle,  reach  the 
dorsal  surface  of  the  metatarsal  phalangal  articulations,  apply  themselves  to  the  inner 
edges  of  the  corresponding  tendons  of  the  extensor  brevis,  receive  some  expansions  from 
the  interossei  and  lumbricales,  and  are  arranged  in  precisely  the  same  manner  as  the  ex- 
tensor tendons  of  the  fingers,  forming  a  fibrous  sheath  on  the  dorsal  surface  of  the  first 
phalanx  of  the  toes  ;  and  like  these,  having  arrived  at  the  articulations  of  the  first  with 
the  second  phalanges,  each  divides  into  three  portions  :  one  median,  attached  to  the  pos- 
terior extremity  of  the  second  phalanx ;  and  two  lateral,  which  unite  upon  the  dorsal  sur- 
face of  the  second  phalanx,  to  be  inserted  into  the  posterior  extremity  of  the  third. 

Relations. — Internally  this  muscle  is  in  relation  with  the  tibialis  anticus,  from  which 
it  is  soon  separated  by  the  extensor  proprius  pollicis,  and  externally  with  the  peroneus 
longus  and  brevis.  It  is  covered  by  the  fascia  of  the  leg  and  foot,  and  it  covers  the  fibula, 
the  interosseous  ligament,  the  ankle-joint,  the  extensor  brevis  digitorum,  which  separ- 
ates it  from  the  tarsus  and  metatarsus ;  lastly,  it  covers  the  toes. 

Action. — As  in  all  reflected  muscles,  we  must  suppose  the  power  to  be  exerted  imrne- 
diately  after  its  reflection,  and  in  the  direction  of  the  reflected  portion  :  in  this  way,  it  will 
be  seen  that  it  extends  the  third  phalanges  upon  the  second,  and  the  second  upon  the 
first ;  and  having  produced  this  effect,  it  flexes  the  foot  upon  the  leg.  From  its  obliqui- 
ty, it  also  draws  the  toes  outward,  and  turns  the  sole  of  the  foot  inward. 

The  Extensor  Proprius  Pollicis. 

The  extensor  proprius  pollicis  {d,fig.  128)  is  an  elongated,  thin,  flat  muscle,  placed  in 
front  of  the  leg,  betwisen  the  extensor  longus  digitorum  and  the  tibialis  anticus. 

Attachments. — It  arises  from  the  interned  surface  of  the  fibula,  and  slightly  from  the 
adjacent  part  of  the  interosseous  ligament,  within  and  behind  the  extensor  communis 
This  origin  is  situated  at  variable  heights,  but  commonly  not  above  the  middle  third 
of  the  leg.  It  is  inserted  into  the  posterior  extremity  of  the  second  phalanx  of  the  great 
toe.  The  fleshy  fibres  arise  directly  from  the  fibula  and  the  interosseous  ligeiment,  and 
proceed  at  first  vertically  around,  and  then  obliquely  behind  a  tendon,  which  occupies  the 
anterior  border  of  the  muscle,  and  to  which  the  fleshy  fibres  are  all  attached  in  a  sloping 
manner,  like  the  barbs  of  a  feather,  as  far  down  as  below  the  proper  sheath  formed  for 
it  at  the  tarsus.  From  thence  the  tendon  is  reflected  at  a  right  angle,  proceeds  oblique- 
ly and  horizontally  forward  and  inward  upon  the  dorsum  of  the  foot,  passes  along  the 
dorsal  surface  of  the  first  metatarsal  bone  and  first  phalanx  of  the  great  toe,  to  the  latter 
of  which  it  gives  off  a  prolongation  on  each  side,  and  is  then  inserted  into  the  second 
phalanx. 

Relations. — Internally,  it  is  in  relation  with  the  tibialis  anticus,  from  which  it  is  sep 
arated  behind  by  the  anterior  tibial  nerve  and  vessels  ;  and  externally,  with  the  extensor 
longus  digitorum.  Its  anterior  border,  at  first  concealed  between  the  preceding  muscles, 
is  soon  situated  immediately  beneath  the  fascia,  and  during  its  contraction  forms  a  pro- 
jection, which  it  is  important  to  know,  because  it  serves  as  a  guide  in  searching  for  the 
dorsal  artery  of  the  foot,  which  will  always  be  found  on  the  outer  margin  of  the  tendon  : 
it  may  be  called  the  muscle  of  the  arteria  dorsalis  pedis.  In  the  foot  it  crosses  superfi- 
cially to  the  extensor  brevis  digitorum. 

Action. — It  extends  the  second  phalanx  of  the  great  toe  upon  the  first,  and  that  upon 
the  metatarsus  ;  when  this  is  accomplished,  it  flexes  the  foot  upon  the  leg.  In  conse- 
quence of  its  obliquity,  it  tends,  like  the  preceding  muscle,  to  turn  the  toes  outward,  and 
slightly  to  elevate  the  inner  border  of  the  foot. 

External  Region  of  the  Leg. 
In  this  region  are  found  the  peroneus  longus  and  peroneus  brevis  muscles. 


9^  MYOLOGY. 

The  Peroneus  Longus.  «k-«.'i 

Dissection. — This  is  common  to  both  muscles.  Remove  the  skin  on  the  outer  side  of 
the  leg  ;  make  a  vertical  incision  through  the  fascia ;  reflect  the  two  flaps,  in  order  to  ar- 
rive at  the  tendinous  septa  dividing  the  peronei  from  the  muscles  of  both  the  anterior 
and  posterior  regions  of  the  leg.  To  expose  these  muscles  in  the  foot,  remove  the  outer 
portion  of  its  dorsal  fascia,  and  divide  obliquely  inward  and  forward  all  the  muscles  of 
the  pkntar  region,  from  the  groove  of  the  cuboid  to  the  posterior  extremity  of  the  first 
metatarsal  bone. 

The  peroneus  longus  {e,figs.  128  to  130)  is  a  long,  thick  muscle,  prismatic  and  trian- 
gular at  its  upper  part,  and  superficially  situated  on  the  outer  side  of  the  leg  (peroneus 
primus,  Spigelius). 

Attachments. — It  arises  externally  from  the  outer  and  anterior  part  of  the  head  of  the 
fibula  ;  from  a  small  portion  of  the  contiguous  part  of  the  external  tuberosity  of  the  tibia ; 
from  the  upper  third  of  the  external  surface  of  the  fibula ;  and  from  the  anterior  and  pos- 
terior borders  of  that  bone,  by  means  of  very  strong  tendinous  septa,  interposed  between 
it  and  the  anterior  and  posterior  muscles  of  the  leg ;  lastly,  from  the  fascia  of  the  leg 
superiorly.  It  is  imerted  into  the  posterior  extremity  of  the  first  metatarsal  bone,  on  the 
outer  side  of  which  a  process  exists  for  this  purpose. 

From  these  very  numerous  origins,  the  fleshy  fibres  proceed  vertically  and  form  a  bun- 
dle {e,fig.  130),  thick  above,  thin  and  flat  below,  and  terminating  in  a  tendon  which  is  at 
first  concealed  in  the  substance  of  the  muscle,  but  appears  in  the  form  of  a  band  on  its 
outer  side,  a  little  above  the  middle  of  the  fibula,  and  becomes  narrower  and  thicker  as  it 
proceeds.  Tlie  tendon  soon  leaves  the  fleshy  fibres,  and  accompanies  the  external  sur- 
face of  the  fibula  as  it  turns  backward  (peroneus  posticus,  Riol),  then  passes  behind  the 
external  malleolus  in  a  groove  common  to  it  and  to  the  peroneus  brevis,  and  is  reflected 
forward  and  downward  to  the  outer  side  of  the  os  calcis,  upon  which  it  is  held  by  a  sep- 
arate sheath.  Having  reached  the  outer  side  of  the  cuboid  bone,  it  is  again  reflected, 
enters  a  groove  running  obliquely  inward  and  forward  upon  the  lower  surface  of  that 
bone  {e,figs.  132,  133),  where  it  is  retained  by  a  very  strong  and  compact  sheath,  and 
continues  its  oblique  course,  without  any  deviation,  along  the  lower  surface  of  the  tarsal 
bones  ;  as  far  as  the  posterior  extremity  of  the  first  metatarsal  bone.  In  this  way  the 
tendon  of  the  peroneus  longus  undergoes  a  double  reflection  :  first,  behind  the  external 
malleolus,  in  which  situation  a  thickening  or  knot  is  often  seen  ;  and,  secondly,  at  the 
cuboid  bone,  opposite  which  a  sesamoid  bone  almost  always  exists.  There  are  also 
three?  fibrous  sheaths,  and  three  synovial  membranes  belonging  to  this  tendon,  one  be- 
hind the  external  malleolus,  one  upon  the  outside  of  the  os  calcis,  and  a  third  under  the 
cuboid  bone. 

Relatioiis. — In  the  leg,  the  peroneus  longus  is  covered  by  the  skin  and  the  fascia  of  the 
leg  :  it  covers  the  peroneus  brevis.  In  front,  a  tendinous  septum  intervenes  between  it 
and  the  extensor  longus  digitorum :  behind,  another  inter-muscular  septum  exists  between 
it  and  the  soleus  above,  and  the  flexor  proprius  below.  On  the  outside  of  the  foot,  its 
tendon  corresponds  to  the  skin  externally,  and  to  the  os  calcis  internally.  In  the  plantar 
region,  it  is  covered  below  by  the  entire  thickness  of  the  soft  parts,  and  corresponds 
above  to  the  inferior  tarsal  ligaments. 

Action. — As  we  have  already  so  frequently  observed,  a  reflected  muscle  acts  as  if  the 
power  were  applied  at  the  point  of  reflection.  In  this  way,  by  transferring  the  power  to 
the  outer  end  of  the  groove  on  the  cuboid  bone,  we  shall  find  that  the  foot  is  abducted, 
or,  rather,  rotated  outward  by  this  muscle  ;  by  next  supposing  the  power  to  act  from  the 
other  point  of  reflection,  i.  e.,  from  behind  the  external  malleolus,  we  may  observe  that 
the  foot  is  extended  upon  the  leg,  and  its  outer  border  turned  upward.  In  this  move- 
ment, the  lower  end  of  the  external  articular  surface  of  the  astragalus  tends  to  carry  the 
external  malleolus  outward,  and  to  increase  the  curvature  of  the  fibula,  which  is  some- 
times fractured  in  consequence.  It  may  be  easily  conceived  that  if  the  fibula  be  frac- 
tured, the  contraction  of  this  muscle  will  no  longer  be  counteracted,  and  accordingly 
will  turn  the  sole  of  the  foot  outward,  and  may  luxate  the  astragalus  inward.  This  is 
the  mechanism  of  luxation  of  the  foot  occurring  after  fracture  of  the  fibula,  the  only 
species  of  lateral  dislocation  of  this  part  which  has  ever  been  observed.* 

The  Peroneus  Brevis. 

The  peroneus  brevis  o{  Albinus  (peroneus  secundus,  Spigel ;  le  petit  peronier,  Wins- 
tmB,f,figs.  129,  130)  is  a  flat,  penniform,  and  reflected  muscle,  smaller  and  shorter  than 
the  preceding,  beneath  which  it  lies. 

Attachments. — It  arises  from  the  lower  half,  sometimes  from  the  lower  two  thirds  of 
the  external  surface  of  the  fibula,  which  is  more  or  less  excavated  for  this  purpose  ;  from 
the  anterior  and  posterior  borders  of  the  same  bone,  and  from  the  tendinous  septa  exist- 
ing between  this  muscle  and  those  of  the  anterior  and  posterior  regions  of  the  leg. 

It  is  inserted  into  the  posterior  extremity  of  the  fifth  metatarsal  bone,  and  sometimes 

*  See  the  admirable  memoir  by  M.  Dupuytren,  on  fracture  of  the  fibula. 


THE   GASTROCNEMIUS. 


2B1 


CYcn,  by  a  tendinous  expansion,  into  the  fourth  metatarsal  bone ;  it  often  gives  off  a  pro- 
longation to  the  extensor  tendon  of  the  httle  toe. 

The  fleshy  fibres  proceed  successively  from  their  different  origins  to  the  internal  sur- 
face and  edges  of  a  tendon,  situated  upon  the  outer  surface  of  the  muscle  ;  the  bundle 
which  they  form  gradually  increases  in  size,  and  then  diminishes,  is  at  first  penniform, 
and  afterward  semi-penniform,  and  accompanies  the  tendon  as  far  as  the  fibrous  sheath 
behind  the  external  malleolus  :  after  leaving  the  sheath,  the  tendon  enters  another,  prop- 
er to  itself,  upon  the  outer  side  of  the  os  calcis,  above  that  for  the  tendon  of  the  peroneus 
longus,  and  passes  somewhat  obliquely  downward  and  forward,  to  be  inserted  into  the 
base  of  the  fifth  metatarsal  bone. 

Relations. — It  is  covered  by  the  peroneus  longus,  and  covers  the  fibula  and  the  outer 
side  of  the  os  calcis.  It  is,  therefore,  only  in  comparison  with  the  peroneus  longus  that 
Riolanus  and  others  have  called  this  muscle  the  anterior  peroneus. 

Action. — The  same  as  that  of  the  peroneus  longus,  with  the  exception  of  that  of  its 
subtarsal  portion.  Thus,  supposing  the  power  to  be  applied  at  the  external  malleolus, 
we  have  extension  of  the  fifth  metatarsal  bone  upon  the  cuboid  ;  extension  and  rotation 
inward  of  the  second  row  of  the  tarsus  upon  the  first ;  rotation  of  the  calcaneum  upon 
the  astragalus ;  extension,  and  a  tendency  to  abduction  of  the  entire  foot,  which  is 
therefore  considerably  everted  when  the  fibula  is  fractured. 

PosTEKioK  Region. 
There  are  two  layers  in  this  region :  one  superficial,  formed  by  the  gastrocnemius  and 
soleus  (or  triceps  suralis)  and  the  plantaris ;  the  other  deep,  consisting  of  the  popliteus, 
the  tibialis  posticus,  the  flexor  longus  digitorum,  and  the  flexor  longus  pollicis. 

The  Gastrocnemius  and  Soleus,  or  Triceps  Suralis,  and  the  Plantaris. 
Dissection. — Make  a  vertical  incision  from  the  upper  part  of  the  popliteal  space  to  the 
heel ;  at  right  angles  to  this,  above,  make  another  horizontal  and  semicircular  incision, 
embracing  the  back  part  of  the  thigh ;  divide  and  dissect  the  fascia  of  the  leg.  The  gas- 
trocnemii  will  then  be  exposed,  and  must  be  dissected  very  carefully  at  their  origins.  In 
order  to  study  the  structure  and  attachments  of  these  muscles  properly,  they  must  be 
cut  transversely  in  the  middle,  and  the  superior  half  turned  upward.  In  dividing  the 
outer  head  of  the  gastrocnemius,  be  careful  not  to  cut  the  plantaris,  which  seems  to  be 
merely  a  small  fasciculus  detached  from  that  muscle.  The  soleus  is  exposed  by  simply 
removing  the  gastrocnemius ;  but,  in  order  to  study  its  structure  and  attachments,  it 


must  be  divided  vertically  from  behind  forward  at  the  side  of  a 
median  tendinous  raph^,  and  the  fibres  which  conceal  this  median 
aponeurotic  lamina  of  the  muscle  must  be  scraped  away.  From 
this  division  we  have  a  fibular  and  a  tibial  portion  of  the  soleus. 

The  gastrocnemius  (g  g)  and  the  soleus  (i  i',Jig.  129)  together 
constitute  a  very  powerful  triceps  muscle  (musculus  surae.  Seem.), 
which,  by  itself,  forms  the  fleshy  part  of  the  leg,  commonly  called 
the  calf  The  great  development  of  these  muscles  is  one  of  the  most 
marked  characteristics  of  the  muscular  apparatus  of  the  human  sub- 
ject, and  is  connected  with  his  destination  for  the  erect  position. 
The  three  portions  of  the  triceps  suralis  are  united  together  below 
in  a  common  tendinous  insertion,  constituting  the  tendo  Achillis  {t, 
Jig.  129),  but  are  divided  above  into  two  very  distinct  planes :  one, 
anterior  or  deep,  formed  by  the  soleus ;  the  other,  posterior  or  su- 
perficial, consisting  of  the  two  heads  of  the  gastrocnemius.  We 
shall  describe  these  in  succession. 

Gastrocnemius. 

The  gastrocnemius,  from  yaarrip,  a  belly,  and  Kv^firj,  the  leg  (ge- 
mellus, Albinus ;  primus  pedem  moventium,  cum  secundo,  Vcsalt- 
us),  is  the  most  superficial  muscle  on  the  back  of  the  leg  :  it  con- 
sists of  two  heads  above  {g  g',fig.  129),  but  forms  a  single  fleshy 
belly,  which  is  thick  and  flattened  from  before  backward. 

It  arises  from  the  condyle  of  the  femur  by  two  perfectly  distinct 
but  similar  heads,  viz.,  an  outer  or  smaller,  called  the  gemellus  ex- 
ternus  {g),  and  an  inner  or  larger,  named  the  gemellus  internus  (g-')- 
They  take  their  origin  from  the  bone,  by  two  very  strong  and  flat 
tendons,  which  are  attached  on  the  outer  side,  and  behind  the  con- 
dyle of  the  femur,  to  two  well-marked  digital  impressions,  that  for 
the  outer  head  being  situated  above  a  much  deeper  impression  foi 
the  popliteus  muscle,  and  that  for  the  inner  head  inmiediately  be 
hind  the  tubercle  into  which  the  adductor  magnus  is  inserted,  so 
that  the  inner  head  is  situated  upon  a  plane  a  little  posterior  to  that 
of  the  outer  head.     They  also  arise,  by  tendinous  fasciculi,  from 

Nn 


Fig.  139. 


S82  MYOLOGY. 

the  rough  triangular  surfaces  surrounding  the  digital  impression,  and  terminating  at  the 
inferior  bifurcation  of  the  linea  aspera.  Each  tendon  of  origin  (that  for  the  inner  being 
much  larger  than  that  for  the  outer  head)  expands  into  an  aponeurosis  upon  the  posteri- 
or surface  of  that  portion  of  the  muscle  to  which  it  belongs.  The  aponeurotic  expansion 
of  the  inner  head  is,  moreover,  thicker  and  longer  than  the  other,  and  embraces  the  inner 
border  of  that  part  of  the  muscle,  like  a  tendinous  semi-cone.  The  fleshy  fibres  arise 
from  the  anterior  surface  of  these  tendinous  expansions,  and  are  disposed  in  the  follow- 
ing manner :  those  in  the  middle,  which  are  few  in  number,  are  strengthened  by  fleshy 
fibres  proceeding  from  the  rough  projections  of  the  bifurcation  of  the  linea  aspera,  pass 
inward  and  downward,  and  are  united  together  like  the  limbs  of  the  letter  V  opening  up- 
ward, upon  a  median  raphe,  which  consists  either  of  a  simple  thickening  of  the  termina- 
ting aponeurosis,  or  of  a  small  tendinous  septum :  the  other  fibres,  constituting  almost 
the  entire  muscle,  arise  from  the  anterior  surface  of  the  tendons  of  origin,  and  from  the 
aponeurosis  in  which  they  terminate,  and  proceed  vertically  downward  to  the  back  of  an- 
other very  dense  aponeurotic  expansion,  which  covers  the  whole  anterior  surface  of  the 
muscle.  This  last  aponeurosis  commences  above  by  two  very  distinct  portions  ;  at  first 
it  is  of  equal  breadth  with  the  muscle,  then  becomes  narrower  and  thickened,  and,  finally, 
closely  united  with  the  terminal  tendon  of  the  soleus.  At  the  lower  part  of  the  calf  the 
fleshy  fibres  terminate  suddenly  upon  the  posterior  surface  of  this  aponeurosis,  forming 
a  V  opening  downward.  Although  the  two  portions  of  the  gastrocnemius  become  inti- 
mately united  shortly  after  their  origin,  they  are  not  confounded  together,  and  the  inter- 
nal portion  forms  on  the  inside  of  the  tibia  the  greatest  part  of  the  fleshy  mass  called  the 
calf  of  the  leg. 

Relations. — The  gastrocnemius  is  covered  by  the  fascia  of  the  leg,  and  it  covers  and 
adheres  intimately  to  the  capsular  ligament,  which  envelops  the  back  part  of  the  con- 
dyles of  the  femur.     It  is  also  in  relation  with  the  popliteus  and  the  soleus. 

The  tendon  of  the  inner  head  corresponds  to  the  posterior  surface  of  the  internal  con- 
dyle ;  that  of  the  outer  head  to  the  outer  side  of  the  external  condyle.  We  often  find 
at  the  upper  part  of  the  tendon  of  each  head,  but  most  commonly  in  the  substance  of 
that  of  the  outer  head,  a  sesamoid  bone,  that  glides  upon  the  back  of  the  condyle,  and 
belongs  to  the  sort  of  fibrous  capsule  or  hood  by  which  the  back  of  each  condyle  is  cov- 
ered.    (Vide  Syndesmology,  Articulation  of  the  Knee.) 

The  Plantaris. 

This  little  muscle  (le  plantaire  grele,  1 1',  Jig.  129)  should  be  regarded  as  an  accessory 
of  the  outer  head  of  the  gastrocnemius,  or,  rather,  as  a  rudimentary  muscle  in  the  hu- 
man subject.  Its  small  fusiform,  fleshy  belly,  varying  much  in  size,  is  found  beneath  the 
outer  head  of  the  gastrocnemius. 

It  arises  {I)  from  the  fibrous  capsule  covering  the  external  condyle,  and  sometimes  from 
the  lower  part  of  the  external  bifurcation  of  the  linea  aspera.  From  these  points,  it  pass- 
es obUquely  downward  and  inward,  and  after  a  course  of  from  two  inches  and  a  half  to 
three  inches,  ends  in  a  long,  flat,  and  slender  tendon,  which  is  at  first  situated  between 
the  gastrocnemius  and  soleus,  and  afterward  (/')  lies  parallel  with  the  inner  edge  of  the 
tendo  Achillis,  and  is  inserted  into  the  os  calcis,  either  at  the  side,  or  in  front  of  that  ten- 
don. Sometimes,  however,  it  is  lost  in  the  sub-cutaneous  adipose  tissue.  This  muscle, 
which  is  often  wanting,  is  occasionally  double.* 

The  Soleus. 

The  soleus  (partly  seen  at  i  i',fig.  129)  is  so  called  because  it  has  been  compared  to 
the  fish  called  a  sole,  or  to  the  sole  of  a  shoe. 

Attachments. — It  arises  from  the  fibula  and  tibia,  and  is  inserted  into  the  os  calcis.  Its 
fibular  origins  (i)  consist,  first,  of  a  tendon  attached  behind,  and  on  the  inner  side  of  the 
head  of  that  bone  ;  this  tendon  is  extremely  strong,  especially  on  the  inside,  opposite  a 
process  existing  on  the  fibula  for  its  attachment ;  it  is  prolonged  within  the  substance, 
Snd  along  the  anterior  surface  of  the  muscle  :  and,  secondly,  of  some  tendinous  fibres 
attached  to  the  upper  half  of  the  external  border  of  the  fibula,  and  the  upper  third  of  the 
posterior  surface  of  the  same  bone. 

The  tibial  origins  {i')  take  place  from  the  oblique  line  on  the  posterior  surface  of  the 
tibia  below  the  popliteus,  and  from  the  contiguous  portion  of  the  aponeurotic  expansion 
of  that  muscle ;  from  an  aponeurosis  which  arises  from  the  middle  third  of  the  inner 
border  of  the  tibia,  and  is  prolonged  upon  the  anterior  surface,  within  the  substance  of 
the  muscle  ;  and,  lastly,  by  a  few  fleshy  fibres  from  a  tendinous  arch  extending  between 
the  head  of  the  fibula  and  the  oblique  line  on  the  posterior  surface  of  the  tibia.  From 
these  diflferent  origins,  the  fleshy  fibres  pass  in  different  directions  to  the  anterior  sur- 
face and  edge  of  an  aponeurosis,  which  covers  the  posterior  surface  of  the  muscle,  be- 
comes narrower  and  thickened  as  it  proceeds  downward,  unites  with  the  terminal  ten- 
don of  the  gastrocnemius  about  the  middle  third  of  the  leg,  and  is  soon  blended  with  it 
to  form  the  tendo  Achiljis. 

*  Fourcroy,  in  his  sixth  memoir  upon  the  liursce  mucosa;,  states  that  the  plantaris,  whose  tendon,  according 
to  Albinus,  is  received  into  a  groove  along^  the  inner  border  of  the  tendo  Achillis,  is  the  tensor  muscle  of  the 
synovial  capsule  of  that  tendon.     This  is  an  error. 


THE   POPHTEUS. 

In  order  to  study  accurately  the  structure  of  the  soleus,  divide  it  longitudinally  at  the 
aide  of  tlie  raphes  or  tendinous  septum  existing  in  the  middle  of  the  lower  half  of  this 
muscle,  and  then,  by  scraping  off  some  of  the  fleshy  fibres,  it  will  be  seen  that  a  dense, 
fibrous  septum  given  off  by  the  terminal  aponeurosis,  separates  the  muscle  into  two  equal 
halves,  and  forms  with  that  aponeurosis  two  tendinous  semi-cones,  in  the  interior  of 
which  the  fleshy  fibres  are  received.  It  will  now  be  understood  why  Douglas,  who  had 
designated  the  gastrocnemius  the  two  external  and  superficial  heads  of  the  great  extensor 
of  the  tarsus,  should  call  the  soleus  the  two  internal  and  deep  heads  of  the  same  muscle 
There  are,  in  fact,  two  principal  aponeuroses  of  origin,  and  two  hollow  tendons  of  insei- 
tion  ;  each  aponeurosis  of  origin  covers  almost  the  entire  anterior  surface  of  tlie  corre- 
sponding half  of  the  muscle. 

Relations. — It  is  covered  by  the  gastrocnemius,  which  projects  beyond  it  on  both  sides, 
but  especially  on  the  inner  side,  and  from  which  it  is  separated  by  the  plantaris.  It  is 
thickest  immediately  below  the  largest  part  or  belly  of  the  inner  portion  of  the  gastroc- 
nemius, and,  consequently,  it  prolongs  the  swelling  of  the  calf  downward.  It  covers  the 
muscles  of  the  deep  layer,  viz.,  the  flexor  communis  digitorum,  the  flexor  proprius  polli- 
cis,  and  the  tibialis  posticus  ;  it  also  covers  the  posterior  tibial  and  the  fibular  vessels 
and  nerves. 

The  Tendo  Achillis. — ^The  tendo  Achillis  {I,  figs.  129, 130)  results  from  the  union  of  the 
tendons  of  the  gastrocnemius,  plantaris,  and  soleus.  It  is  formed  in  the  following  man- 
ner :  the  terminal  aponeurosis  of  the  gastrocnemius,  shortly  after  leaving  the  Ik  f<liy 
fibres,  is  intimately  united  to  that  of  the  soleus,  which  still  continues  to  receive  fleshy 
fibres  upon  its  anterior  surface  and  its  edges,  and  gradually  becoming  narrower,  is  soon 
joined  by  the  antero-posterior  septum  of  this  muscle.  All  these  tendinous  fibres  are  col- 
lected together  to  form  the  strongest  and  largest  tendon  in  the  body,  known  by  the  name 
of  the  tendo  Achillis,  which,  after  a  course  of  about  an  inch  and  a  half  or  two  inches, 
glides  over  the  smooth  surface  presented  by  the  superior  two  thirds  of  the  back  of  the 
OS  calcis,  with  the  intervention  of  a  synovial  bursa,  and  is  expanded  a  little,  in  order  to 
be  inserted  into  the  rough  surface  on  the  lower  part  of  the  same  bone. 

Action  of  the  Gacirocnemius  and  Soleus. — These  muscles  extend  the  foot  upon  the  leg. 
In  no  other  part  of  the  body  do  we  find  so  advantageous  an  arrangement  for  an  immense 
development  of  power.  1.  These  muscles  are  very  large,  and  particularly  remarkable  for 
the  number  of  their  fleshy  fibres,  in  which  respect  they  exceed  all  other  muscles  in  the 
body.  2.  The  mode  of  insertion  is  nowhere  else  so  favourable,  for  it  is  absolutely  per- 
pendicular. 3.  We  have  here  a  lever  of  the  second  order,  in  which  the  fulcrum  is  at  the 
ball  of  the  toes,  the  resistance  in  the  middle  of  the  foot,  being  represented  by  the  weight 
of  the  body  resting  upon  the  ankle-joint,  and  the  _power  at  the  extremity  of  the  heel  (see 
fig.  104).  The  length  of  that  portion  of  the  lever  which  projects  behind  the  joint  varies 
much  in  different  individuals ;  it  scarcely  exists  in  the  peculiar  malformation  denominated 
flat-foot.  These  muscles  are  the  principal  agents  in  walking  and  leaping ;  they  raise 
the  weight  of  the  whole  body,  even  when  loaded  with  heavy  burdens.  Hence  it  is  not 
surprising,  that  occasionally  an  energetic  contraction  of  these  muscles  may  rupture  the 
tendo  Achillis,  or  fracture  the  os  calcis.  Frequent  exercise  appears  to  be  necessary  for 
these  muscles  ;  for  when  they  remain  inactive,  they  become  atrophied,  and  are  speedily 
affected  with  fatty  degeneration.  The  action  of  the  soleus,  which  reaches  only  from  the 
leg  to  the  heel,  is  limited  to  extension  of  the  foot ;  but  the  gastrocnemius,  which  is  at- 
tached to  the  femur,  after  having  extended  the  foot,  can  flex  the  leg  upon  the  thigh  ;  but, 
from  its  proximity  to  the  fulcrum,  this  last  action  is  very  slight.  When  the  foot  is  fixed, 
as,  for  example,  in  standing,  the  soleus  acts  upon  the  leg,  and  tends  to  prevent  one  from 
falling  forward,  to  which  there  is  a  constant  tendency  from  the  weight  of  the  body ;  the 
action  of  the  gastrocnemius,  on  the  contrary,  is  to  flex  the  thigh,  and  in  this  respect  it 
is  altogether  independent  of  the  soleus. 

The  plantaris  can  only  be  regarded  as  rudimentary  in  man  ;  in  the  lower  animals  it 
is  a  tensor  of  the  plantar  fascia ;  it  has  been,  as  it  were,  cut  short  in  man,  in  conse- 
quence of  his  destination  for  the  erect  position.  Sometimes,  as  we  have  already  stated, 
it  is  lost  upon  the  fatty  tissue  covering  the  os  calcis. 

The  Popliteus. 

This  is  a  small,  triangular,  and  very  thin  muscle  {m,fig.  130),  situated  in  the  poplitea? 
space. 

It  arises  from  a  deep  fossa,  resembling  a  groove  running  from  behind  forward,  on  the 
back  of  the  external  condyle  of  the  femur,  below  the  origin  of  the  outer  head  of  the  gas- 
trocnemius. It  is  inserted  into  the  entire  extent  of  the  triangular  surface,  on  the  upper 
part  of  the  posterior  aspect  of  the  tibia. 

It  arises  by  a  very  strong  tendon,  which  bears  no  proportion  to  the  diminutive  size 
of  the  muscle.  This  tendon,  at  first  concealed  by  the  external  lateral  ligament,  contain- 
ed, as  it  were,  in  the  cavity  of  the  joint,  and  completely  enveloped  by  the  synovial  mem- 
brane, passes  obliquely  behind  the  articulation,  and,  after  extending  for  about  one  inch, 


284 


MYOLOGY. 


divides,  like  the  tendon  of  the  obturator  internus,  into  four  or  five  small  diverging  bun- 
IHg.  130.  dl^s,  which  soon  surround  the  fleshy  fibres  on  all  sides.     The  lat- 

ter then  become  attached  in  succession  to  the  triangular  surface 
of  the  tibia,  the  lowest  being  the  longest  and  the  most  oblique. 
The  superficial  fibres  are  inserted  into  a  tendinous  expansion  from 
the  semi-membranosus,  which  covers  the  posterior  surface  of  the 
popliteus  muscle,  and  forms  a  very  strong  sheath  for  it. 

Relations. — It  is  covered  by  the  gastrocnemius  and  the  plantaris, 
from  which  it  is  separated  by  the  popliteal  vessels,  and  the  inter- 
nal popliteal  branch  of  the  sciatic  nerve.  It  covers  the  tibio-fibu- 
lar  articulations  and  the  back  of  the  tibia. 

Action. — It  flexes  the  leg  upon  the  thigh,  and,  at  the  same  time, 
rotates  it  inward  (oblique  movens  tibiam,  Spigelius).  In  this  last 
respect  it  antagonizes  the  biceps. 

The  Tibialis  Posticus. 

Dissection. — Remove  the  gastrocnemius  and  soleus ;  separate 
the  tibialis  posticus  from  the  flexor  longus  digitorum,  which  par- 
tially covers  it ;  carefully  remove  from  the  posterior  surface  of  the 
tibialis  posticus  a  very  broad  aponeurosis,  together  with  a  portion 
of  the  long  flexor  of  the  toes,  which  arises  from  the  posterior  sur- 
face of  that  aponeurosis ;  completely  separate  the  tibialis  posticus 
from  the  interosseous  ligament,  and  the  adjacent  portions  of  the 
tibia  and  fibula  ;  lastly,  be  careful  to  preserve  the  tendinous  expan- 
sions always  given  oflT  by  this  muscle  to  the  fourth  and  fifth  meta- 
tarsal bones. 

The  tibialis  jposticus  {n,fig.  130)  is  the  most  deeply  seated  of  all 
the  muscles  on  the  back  of  the  leg  ;  it  is  very  thick,  and  occupies 
the  whole  depth  of  the  excavation  between  the  tibia,  fibula,  and 
interosseous  ligament. 

Attachments. — It  arises  from  the  tibia,  the  fibula,  and  the  interos- 
seous ligament,  and  is  inserted  into  the  scaphoid  bone.  Its  tibial 
and  fibular  origins  form  a  bifurcation  for  the  passage  of  the  poste- 
rior tibicd  artery.  Its  tibial  attachment  takes  place  on  the  oblique 
line  situated  below  the  popliteus,  soieus,  and  flexor  longus  digitorum.  Its  fibular  origin 
is  from  the  inner  border  of  that  bone,  below  the  soleus,  and  from  all  that  portion  of  its 
inner  surface  which  is  behind  the  interosseous  ligament.  It  also  arises  from  the  entire 
posterior  surface  of  this  ligament.  Lastly,  a  few  fibres  take  their  origin  from  the  deep 
surface  of  an  aponeurosis  which  separates  the  deep  from  the  superficial  layer  of  muscles, 
and  from  the  tendinous  septa  interposed  between  this  muscle  itself  and  the  flexor  lon- 
gus digitorum  on  the  inside,  and  the  flexor  proprius  pollicis  on  the  outside.  From  these 
numerous  origins  the  fleshy  fibres  proceed  vertically  downward,  around  a  tendon  which 
may  be  distinguished  near  the  upper  extremity  of  the  muscle,  under  the  form  of  a  ten- 
dinous sheaf,  which  afterward  appears  along  its  posterior  border,  and  receives  the  fleshy 
fibres  on  its  anterior  surface,  like  the  barbs  of  a  feather  upon  the  shaft.  This  tendon, 
however,  is  nothing  more  than  the  thickened  posterior  edge  of  an  aponeurosis  occupy- 
ing the  entire  substance  of  the  muscle  from  before  backward,  and  receiving  the  fleshy 
fibres  upon  its  two  lateral  surfaces  as  far  down  as  opposite  the  internal  malleolus.  The 
thick  tendon  resulting  from  the  union  of  these  aponeurotic  fibres  then  becomes  free,  and 
enters  a  proper  sheath  on  the  outer  side  of  that  belonging  to  the  tendon  of  the  flexor  longus 
digitorum,  in  front  of  which  it  then  passes  behind  the  internal  malleolus,  where  it  is  also 
enclosed  in  a  separate  sheath  {n,fig.  129).  On  the  inner  side  of  the  internal  lateral  lig- 
ament of  the  ankle,  and  below  the  lower  calcaneo-scaphoid  ligament,  it  enters  another 
sheath,  and  is  finally  inserted  {n,fig.  133)  into  the  tubercle  of  the  scaphoid  bone,  a  very 
thick  sesamoid  bone  existing  near  its  insertion.  In  some  subjects  this  sesamoid  bone 
is  found  at  the  point  of  insertion  ;  in  others  it  is  situated  opposite  the  calcaneo-scaphoid 
ligament.  Besides  this,  the  tendon  of  the  tibialis  posticus  gives  off  a  very  strong  ex- 
pansion to  the  first  cuneiform  bone,  and  on  the  outside  an  oblique  expansion  to  the  sec- 
ond and  third  cuneiform  bones,  and  even  to  the  third  or  fourth  metatarsal  bones. 

Relations. — It  is  covered  by  the  flexor  longus  digitorum,  slightly  by  the  flexor  proprius 
pollicis,  and  entirely  by  the  soleus  :  it  covers  the  interosseous  ligament  and  the  adjacent 
parts  of  the  tibia  and  fibula. 

Action. — The  tibialis  posticus  extends  the  foot  upon  the  leg.  As  it  is  a  reflected  mus- 
cle, all  the  fibres  must  be  considered  as  acting  from  the  point  of  reflection  that  is  be- 
hind the  inner  ankle.  It  is  evident,  then,  that  this  muscle  extends  the  foot,  both  by  its 
action  upon  the  astragalo-scaphoid  articulation,  and  also  by  that  upon  the  ankle-joint. 
It  also  tends  to  turn  the  sole  of  the  foot  inward ;  and,  consequently,  it  co-operates  with 
the  tibialis  anticus  in  this  respect,  and  antagonizes  the  peroneus  longus  and  brevis.  It 
may  also  be  understood  why  some  persons,  in  whom  the  tendo  Achillis  has  been  cut  oi 


THE  FLEXOR  LONGUS  POLLICIS.  2l8^' 

ruptured,  are  yet  capable  of  walking,  and  why  the  foot  can  in  all  cases  be  extended  after 
this  accident ;  but  under  these  circumstances  the  lever  formed  by  the  foot  is  changed, 
and  the  power  represented  by  the  tibialis  posticus  is  applied  between  the  fulcrum  and 
the  resistance  ;  so  that  we  have,  then,  a  lever  of  the  third,  not  of  the  second  order,  as 
when  the  tendo  Achillis  is  uninjured. 

The  Flexor  Longus  Digitorum  Pedis. 

This  is  a  penniform,  elongated,  and  reflected  muscle  {o,figs.  130,  132),  situated  along 
the  posterior  surface  of  the  tibia  and  in  the  sole  of  the  foot ;  it  is  the  most  internal  mus- 
cle of  the  deep  layer,  is  flattened  from  before  backward,  and  terminates  below  in  four 
tendons. 

Attachments. — It  arises  from  the  tibia,  and  is  inserted  into  the  last  phalanges  of  the  last 
four  toes.  It  arises  from  the  oblique  line  of  the  tibia,  below  the  popliteus  and  the  sole- 
us,  and  from  the  middle  three  fifths  of  the  posterior  surface  of  the  same  bone.  Some 
fibres  also  proceed  from  the  tendinous  septum  intervening  between  it  and  the  tibialis 
posticus.  From  these  different  origins  the  fleshy  fibres  proceed  obliquely  backward 
and  downward,  to  the  anterior  surface  and  edges  of  a  tendon  which  commences  near 
the  upper  end  of  the  muscle,  and  gradually  disengages  itself  from  the  fleshy  fibres,  being 
accompanied  by  them  anteriorly  as  far  as  the  internal  malleolus.  It  passes  behind  this 
projection  in  the  same  sheath  as  the  tendon  of  the  tibialis  posticus,  from  which  it  is  sep- 
arated by  a  fibrous  septum ;  it  soon  leaves  that  tendon,  passing  to  its  outer  or  fibular 
side  (o,  fig.  129),  and  is  then  reflected  at  an  obtuse  angle  upon  the  internal  malleolus. 
It  now  becomes  horizontal,  and  is  buried  under  the  astragalus  and  the  small  anterior 
tubercle  of  the  os  calcis,  where  it  is  contained  in  a  proper  sheath.  Having  thus  reached 
the  sole  of  the  foot  (o,  figs.  131,  132),  it  passes  obliquely  outward  and  forward,  crosses 
under  the  tendon  of  the  flexor  longus  pollicis  at  a  very  acute  angle,  receives  from  it  a 
strong  tendinous  communication,  and  at  the  same  time  becoming  expanded,  is  joined  by 
its  accessory  muscle,  and  finally  divides  into  four  tendons  for  the  last  four  toes.  The 
tendon  for  the  second  toe  proceeds  directly  forward.  The  tendons  for  the  other  toes  in 
succession  pass  more  and  more  obliquely.  Having  reached  the  metatarso-phalangal  ar- 
ticulations, these  tendons  are  received,  together  with  those  of  the  flexor  brevis  digitorum, 
into  the  sheaths  upon  the  first  and  second  phalanges  ;  and  they  have  precisely  the  same 
relations  to  the  tendons  of  the  last-mentioned  muscle  as  the  flexor  profundus  is  observed 
to  have  with  regard  to  the  flexor  sublimis  digitorum  in  the  hand  ;  and  hence  the  name 
of  jperforans  given  by  Spigelius  to  the  long  flexor  of  the  toes.  The  tendons  are  finally 
inserted  into  the  posterior  extremities  of  the  third  phalanges.  The  tendinous  parts  of 
this  muscle  are  lubricated  by  synovial  membranes  where  they  pass  through  the  different 
sheaths. 

Relations. — It  is  covered  by  the  soleus,  the  posterior  tibial  vessels  and  nerves,  and  it 
covers  the  tibia  and  the  tibialis  posticus.  In  the  foot,  it  is  covered  below  by  the  flexor 
brevis  digitorum  and  the  adductor  pollicis. 

Action. — It  flexes  the  third  phalanges  upon  the  second,  the  second  upon  the  first,  and 
the  first  upon  the  corresponding  metatarsal  bones.  When  these  movements  have  heen 
accomplished,  it  extends  the  foot  upon  the  leg.  From  the  obliquity  of  its  reflected  por- 
tion, it  would  turn  the  toes  and  the  sole  of  tue  foot  slightly  inward,  if  the  accessory  mus- 
cle did  not,  as  it  were,  rectify  its  action,  as  well  as  co-operate  with  it.  In  standing,  it  op- 
poses flexion  of  the  leg  forward. 

The  Flexor  Longus  Pollicis. 

The  flexor  longus  pollicis  is  the  most  external  and  the  largest  muscle  in  the  deep  re- 
gion of  the  leg :  it  is  prismatic  and  quadrangular,  vertical  and  fleshy  in  the  leg  {p,  figs. 
129,  130),  tendinous  and  horizontal  in  the  foot  {p,figs.  131,  132). 

Attachments. — It  arises  from  the  fibula,  and  is  inserted  into  the  last  phalanx  of  the  great 
toe.  Some  of  the  fibres  arise  directly  from  the  inferior  two  thirds,  and  from  the  internal 
and  external  borders  of  the  fibula ;  others  arise  from  the  fascia  covering  the  tibialis  pos- 
ticus (its  origin  from  the  fibula,  and  that  from  the  fascia  of  the  tibialis  muscle,  are  sep- 
arated from  each  other  by  the  peroneal  vessels) ;  from  a  tendinous  septum  between  it 
and  the  peroneus  longus  and  brevis  ;  and  from  a  small  portion  of  the  lower  part  of  the 
interosseous  ligament.  From  these  numerous  points  of  origin  the  fleshy  fibres  pass  ob- 
fiquely  downward  and  backward,  around  a  tendon  which  occupies  the  entire  length  of 
the  muscle,  and  may  be  seen  at  the  lower  part  of  the  leg,  through  a  thin  layer  of  muscu- 
lar fibres.  These  fibres  terminate  abruptly  behind  the  ankle-joint,  at  the  oblique  groove 
on  the  astragalus,  in  which  the  tendon  is  lodged  ;  it  then  turns  into  a  groove  on  the  os 
cedcis,  forming  a  continuation  of  the  preceding  (^fig.  133),  and  situated  below  that  for  the 
tendon  of  the  flexor  longus  digitorum,  and  dips  into  the  sole  of  the  foot.  It  is  retained 
in  these  two  grooves,  which  run  obliquely  downward,  inward,  and  forward,  by  a  very 
strong  and  continuous  sheath  (fig.  132).  In  the  sole  of  the  foot,  the  tendon  is  deeply 
situated  (p,  fig.  131),  passes  forward,  and  crosses  (p,  fig.  132)  at  an  acute  angle  above 
the  tendon  of  the  flexor  longus  digitorum,  to  which  it  gives  off"  a  considerable  fibrous 


^relf  MYOLOGY. 

prolongation.  It  is  then  received  in  a  groove  formed  between  the  flexor  brevis  digito- 
rum  and  the  oblique  adductor  of  the  great  toe,  passes  below  the  anterior  glenoid  liga- 
ment of  the  metatarso-phalangal  articulation  of  that  toe,  between  the  two  sesamoid 
bones,  and  is  received  into  the  osteo-fibrous  sheath  of  the  first  phalanx,  to  be  inserted 
into  the  posterior  extremity  of  the  second. 

Relations. — It  is  covered  by  the  soleus,  being  separated  from  it  by  a  fascia,  which  in- 
creases in  thickness  as  it  passes  downward ;  it  is  also  covered  by  the  tendo  Achillis  ;  it 
covers  the  fibula,  the  tibialis  posticus,  the  peroneal  artery,  and  the  lower  part  of  the  in- 
terosseous ligament.  Externally,  it  is  in  relation  with  the  peroneus  longus  and  brevis ; 
internally,  with  the  flexor  longus  digitorum. 

Action. — It  flexes  the  second  phalanx  of  the  great  toe  upon  the  first,  and  this  upon  the 
first  metatarsal  bone  ;  having  produced  these  movements,  it  then  extends  the  foot  upon 
he  leg.  From  the  obliquity  of  its  fleshy  belly,  it  has  a  tendency  to  turn  the  great  toe 
and  the  foot  outward.  In  this  respect  it  antagonizes  the  flexor  longus  digitorum  and  the 
tibialis  posticus.  The  very  strong  tendinous  expansion  which  unites  it  to  the  long  flexor, 
of  the  toes  consolidates  the  two  muscles ;  in  fact,  it  is  very  uncommon  to  find  either  of 
them  acting  independently. 


MUSCLES  OF  THE  FOOT. 


The  Extensor  Brevis  Digitorum. — Abductor  Pollicis  Pedis. — Flexor  Brevis  Pollicis  Pedis. — 

Adductor  Pollicis  Pedis. — Transversus  Pollicis  Pedis. — Abductor  Minimi  Digiti. — Flexor 

Brevis  Minimi  Digiti. — Flexor  Brevis  Digitorum. — Flexor  Accessorius. — Lumbricales. — 

Interossei. 

The  muscles  of  the  foot  are  divided  into  those  of  the  dorsal  and  plantar  aspects  and 
the  interossei.  The  muscles  of  the  plantar  aspect  may  be  again  subdivided  into  three 
regions,  viz.,  those  of  the  middle  plantar  region,  those  of  the  internal  plantar  region,  and 
those  of  the  external  plantar  region.  A  single  muscle  occupies  the  dorsum  of  the  foot, 
viz.,  the  extensor  brevis  digitorum.  The  muscles  of  the  internal  plantar  region  are  four 
in  number,  viz.,  the  abductor,  the  flexor  brevis,  and  the  oblique  and  transverse  adduc- 
tors of  the  great  toe.  The  last  two  muscles  may  be  regarded  as  forming  part  of  the 
middle  plantar  region. 

The  muscles  of  the  external  plantar  region  are  the  abductor  and  the  flexor  brevis  of 
the  little  toe. 

The  muscles  of  the  middle  region  are  the  flexor  brevis  digitorum,  the  flexor  accesso- 
rms,  and  the  lumbricales. 

The  interosseous  muscles  are  seven  in  number,  and  are  divided  into  the  dorsal  and 
plantar. 

Dorsal  Region. 

The  Extensor  Brevis  Digitorum. 

DissectKm. — ^Remove  the  dorsal  fascia  of  the  foot,  and  the  tendons  of  the  muscles  of 
the  anterior  region  of  the  leg. 

The  extensor  brevis  digitorum  (q,  fig.  128)  is  a  thin,  flat,  quadrilateral  muscle,  situated 
on  the  dorsum  of  the  foot ;  it  is  divided  into  four  portions  anteriorly,  and  is  an  accessor}' 
of  the  extensor  longus  digitorum.  It  arises  from  the  os  calcis,  and  is  inserted  into  the 
first  four  toes. 

It  arises,  by  a  rounded  extremity,  from  a  small  excavation  on  the  outside  of  the  foot, 
formed  by  the  os  calcis  and  the  astragalus  {the  astragalo-calcanean  fossa),  and  from  the  os 
calcis,  in  front  of  that  excavation.  Its  origin  from  these  parts  is  both  fleshy  and  tendi- 
nous. The  muscle  then  passes  forward  and  inward,  and  soon  divides  into  four  fleshy 
fascicuh,  each  representing  a  little  penniform  muscle,  and  terminating  quickly  in  a  small 
tendon,  the  size  of  which  is  proportioned  to  the  strength  of  the  fasciculus.  The  inter- 
nal tendon  is  the  largest,  because  it  is  intended  for  the  great  toe  ;  it  is  situated  below 
the  tendon  of  the  extensor  proprius  pollicis,  which  it  crosses  at  a  very  acute  angle,  and 
is  inserted  into  the  dorsal  surface  of  the  proximal  end  of  the  last  phalanx.  The  second, 
third,  and  fourth  tendons,  intended  for  the  second,  third,  and  fourth  toes,  are  subjacent 
to  the  corresponding  tendons  of  the  extensor  longus  digitorum,  which  they  cross  at  a 
very  acute  angle.  Having  reached  the  metatarso-phalangal  articulations,  the  tendons  of 
the  short  extensor  are  situated  to  the  outside  of  those  of  the  extensor  longus,  and  are 
blended  with  them,  so  as  to  complete  the  fibrous  sheath  on  the  dorsal  surface  of  the  first- 
phalanx,  and  to  terminate  in  a  similar  manner. 

Relations. — It  is  covered  by  the  dorsal  fascia  of  the  foot,  by  the  tendons  of  the  exten- 
sor longus  digitorum  and  extensor  proprius  pollicis  ;  it  covers  the  second  row  of  the  tar- 
sal bones,  the  metatarsus,  and  a  small  portion  of  the  interosseous  muscles  and  the  pha- 
langes. The  arteria  dorsalis  pedis  runs  at  first  along  the  inner  border  of  this  muscle, 
which  overlaps  the  artery,  where  the  latter  perforates  the  first  interosseous  space,  in 
order  to  reach  the  sole  of  the  foot. 


THE    FLEXOR    BREVIS    POLLICIS    PEDIS. 


28T 


Action. — It  extends  the  first  four  toes ;  it  acts  upon  the  first  phalanx  only  of  the  great 
toe.  Its  obliquity  enables  it  to  correct  the  contrary  oblique  movement  communicated  to 
the  toes  by  the  contraction  of  the  extensor  longus  digitorum  ;  so  that  the  opposite  ac- 
tions of  these  two  muscles  are  mutually  destroyed,  and  the  foot  is  extended  directly. 
Not  uncommonly,  the  extensor  brevis  presents  a  fifth  fasciculus,  which  is  lost  upon 
some  one  of  the  metatarso-phalangal  articulations. 

Internal  Plantar  Region. 
The  muscles  of  the  ball  of  the  great  toe  may  be  divided,  like  those  of  the  thumb,  into 
two  orders,  viz.,  those  which  pass  from  the  tarsus  to  the  inner  side  of  the  first  phalanx, 
and  those  which  pass  from  the  tarsus  to  the  outer  side  of  the  same  phalanx.  Here,  as 
wifli  the  muscles  of  the  thumb,  the  tendon  of  the  flexor  longus  divides  the  flexor  brevis 
poUicis  pedes  of  authors  into  two  parts  :  one  internal,  forming  the  flexor  brevis  of  the 
great  toe,  properly  so  called ;  the  other  external,  which  is  found  to  be  connected  with 
the  oblique  adductor  of  this  toe. 

Muscles  inserted  into  the  Inner  Side  of  the  First  Phalanx  of  the  Great  Toe. 

Dissection. — In  order  to  expose  the  abductor  brevis,  it  is  sufficient  to  remove  the  in- 
ternal plantar  fascia ;  the  flexor  brevis  will  be  found  under,  i.  e.,  deeper  than  the  tendon 
of  the  abductor  brevis. 

The  muscles  inserted  into  the  inner  side  of  the  first  phalanx  of  the  great  toe  are  the 
abductor  brevis  and  the  flexor  brevis.  They  are  distinct  at  their  origins,  but  are  often 
blended  at  their  insertions ;  so  that  Winslow  united  them  together  under  the  name  of 
le  thenar  du  pied. 

The  Abductor  PoUicis  Pedis. 

This  muscle  (le  court  adducteur,*  Cruveilhier,  r,fig.  131)  is 
the  most  superficial  in  the  internal  plantar  region ;  it  arises 
on  the  inside,  from  the  internal  posterior  tuberosity  of  the  os 
calcis ;  from  the  internal  annular  ligament  under  which  the 
posterior  tibial  vessels  and  nerves  pass ;  from  the  upper  sur- 
face of  the  internal  plantar  fascia ;  and  from  the  lower  sur- 
face of  a  tendinous  expansion,  which  occupies  the  entire  ex- 
tent of  the  deep  or  superior  surface  of  the  muscle.  From 
these  points  the  fleshy  fibres  proceed  to  the  circumference  of 
a  tendon  (r,  figs.  132,  133),  which  emerges  from  them  infe- 
riorly  near  the  first  cuneiform  bone,  but  is  often  accompanied 
by  them  superiorly  as  far  as  its  insertion  into  the  internal  ses- 
amoid bone,  opposite  the  first  phalanx  of  the  great  toe. 

Relafio7is. — It  is  covered  below  by  the  internal  plantar  fas- 
cia, and  is  divided  from  the  muscles  of  the  middle  plantar  re- 
gion by  a  tendinous  septum,  which  gives  attachment  to  some 
of  its  fleshy  fibres.  It  is  superficial  to  the  flexor  brevis  poUi- 
cis, the  flexor  accessorius,  the  tendons  of  the  flexor  longus 
digitorum,  and  that  of  the  flexor  longus  poUicis,  the  tarsal  in- 
sertions of  the  tibialis  anticus  and  posticus,  the  plantar  vessels 
and  nerves,  and  the  internal  articulations  of  the  tarsus. 

Action. — It  is,  properly  speaking,  a  flexor  of  the  great  toe. 

The  Flexor  Brevis  PoUicis  Pedis. 

Adopting  a  similar  plan  in  the  definition  of  this  muscle  as  in  that  of  the  short  flexor 
of  the  thumb,  I  shaU  describe  as  the  short  flexor  of  the  great  toe  that  portion  {s,fig.  133) 
only  of  the  flexor  brevis  of  authors  which  extends  from  the  second  row  of  the  tarsus  to 
the  internal  sesamoid  bone  of  the  metatarso-phalangal  articulation  of  the  great  toe,  and 
sliall  refer  to  the  oblique  adductor  that  portion  (t)  which  is  attached  to  the  external  ses- 
imoid  bone.  This  change  appears  to  be  warranted  by  the  rule  already  laid  down  for  the 
distinction  of  muscles.  Community  of  tlje  fixed  points  of  origin  is  not  sufficient  to  es- 
tablish the  unity  of  two  muscles,  provided  their  movable  insertions  are  distinct.  A  cel- 
lular interval  and  the  tendon  of  the  flexor  longus  poUicis  establish  anteriorly  the  line  of 
demarcation  between  the  flexor  brevis  and  the  adductor  obliquus  poUicis. 

According  to  this  view,  the  flexor  brevis  poUicis  (s,  figs.  131,  132,  133)  arises  from 
the  second  row  of  the  tarsus,  particularly  from  the  cuboid  and  the  third  cuneiform  bones, 
by  some  tendinous  fibres  which  are  formed  by  a  continuation  of  the  inferior  ligaments  of 
the  tarsus,  and  are  common  to  this  muscle  and  the  internal  portion  (t)  of  the  obliqne  ad- 
ductor of  the  great  toe.  The  tendon  of  the  tibialis  posticus  {n,fig.  133),  or,  rather,  the 
prolongation  which  this  tendon  gives  off  to  the  fourth  metatarsal  bone,  also  furnishes 
Bome  points  of  origin.  The  fleshy  fibres  proceeding  from  these  different  attachments 
form  a  bundle  that  gradually  increases  in  size,  becomes  separated  from  the  oblique  ad- 

*  See  note,  next  page. 


MYOLOGY. 

ductor,  and  terminates  in  a  tendon  which  is  inserted  into  the  external  sesamoid  bone, 
and  also  into  the  glenoid  ligament  of  the  metatarso-phalangal  articulation.  Not  unfre- 
quently  the  greater  number  of  the  fleshy  fibres  are  attached  to  the  tendon  of  the  abduc- 
tor brevis,  and  thus  constitute  the  short  head  of  a  biceps  muscle. 

Relations. — The  flexor  brevis  pollicis  is  in  relation  below  with  the  internal  plantar  fas- 
cia, and  with  the  tendon  of  the  abductor  brevis  pollicis,  being  moulded  upon  it,  and  usu- 
ally separated  from  it  by  a  tendinous  sheath,  except  in  those  cases  where  the  two  mus- 
cles are  blended  together.  Observe  that,  at  the  point  where  the  fleshy  belly  of  the  ab- 
ductor terminates,  the  flexor  brevis  is  in  relation  above  with  the  tendon  of  the  peroneus 
longus  {e,fig.  133)  and  the  first  metatarsal  bone.  ^ 

Action. — The  same  as  that  of  the  preceding  muscle,  but  it  is  much  less  powerful,  ajid 
less  extensive. 

Muscles  inserted  into  the  External  Side  of  the  First  Phalanx  of  the  Great  Toe. 

These  are  the  oblique  and  transverse  adductors.* 

Dissection. — They  are  exposed  by  cutting  across,  and  turning  forward  the  flexor  brevis 
digitorum,  the  tendons  of  the  flexor  longus  digitorum,  and  the  flexor  accessorius  :  par- 
ticular care  should  be  taken,  when  the  dissection  has  extended  as  far  as  the  heads  of  the 
metatarsal  bones,  to  avoid  cutting  the  small  transverse  adductor. 

The  jJdductor  Pollicis  Pedis. 

This  (I'abducteur  oblique,  Cruveilhier,  tt',fig.  133)  is  the  largest  of  all  the  plantar  mus- 
cles ;  it  is  prismatic  and  triangular,  and  occupies  the  great  hollow  formed  by  the  last  four 
metatarsal  bones,  and  is  bounded  by  the  first  metatarsal  bone  on  the  inner  side.  It  ex- 
tends from  the  second  row  of  the  tarsus  to  the  external  sesamoid  bone  of  the  great  toe. 
It  arises  by  two  very  distinct  portions  :  the  smaller  {t,figs.  131,  132,  133),  common  to  it 
and  to  the  flexor  brevis,  proceeds  from  the  cuboid  bone  ;  the  other  (f )  is  mucli  larger, 
and  arises  Irom  the  slieath  of  the  tendon  of  the  peroneus  longus  (e),  from  the  posterior 
extremities  of  the  tiiird,  foiu-th,  and  fifth  metatarsal  bones,  and  from  the  transverse  lig- 
aments by  which  they  are  united.  From  these  different  origins  the  fleshy  fibres  pass 
more  or  less  obli<juely  inward,  and  are  inserted  by  a  tendinous  bundle  into  the  external 
sr-yaiiHiid  bone  of  the  metatarso-phalangal  articulation  of  the  great  toe,  and  into  the  pos- 
terior edge  of  the  glenoid  ligament  of  the  same  joint. 

Relations. — Its  inferior  surface  is  in  relation  with  the  long  and  short  flexors  of  the  toes, 
with  tlie  flexor  accessorius,  the  lumbricales,  and  the  plantar  fascia  ;  its  superior  surface, 
with  the  interosseous  muscles  and  the  external  plantar  artery  ;  audits  inner  surface,  with 
the  first  metatarsal  bone,  the  tendon  of  the  peroneus  longus,  and  with  the  flexor  brevis 
pollicis. 

Action. — It  is  a  powerful  adductor  and  flexor  of  the  great  toe. 

The  Transversus  Pollicis  Pedis. 

This  small  transverse  bundle  (I'abducteur  transverse,  Cruveilhier,  u,  fig.  133)  forms  an 
appendage  of  the  preceding  muscle,  and  is  represented  in  the  hand  by  the  transverse 
fibres  of  the  adductor  pollicis  ;  it  extends  from  the  fifth  metatarsal  bone  to  the  external 
sesamoid  bone  of  the  metatarso-phalangal  articulation  of  the  great  toe. 

This  muscle,  which  is  of  variable  size,  arises  externally  from  beneath  the  head  of  the 
fifth  metatarsal  bone,  by  a  tendinous  and  fleshy  tongue,  which  is  directed  transversely 
inward,  is  strengthened  by  other  fibres  arising  from  the  anterior  transverse  ligament  of 
the  metatarsus,  and  from  the  interosseous  aponeurosis,  and  is  inserted  into  the  outer  side 
of  the  first  phalanx  of  the  great  toe,  where  it  is  often  blended  with  the  attachment  of  the 
oblique  adductor. 

Relations. — It  is  in  relation  below  with  the  tendons  of  the  long  and  short  flexors  of  the 
toes  and  with  the  lumbricalis,  and  above  with  the  interosseous  muscles.  It  is  lodged  ia 
the  anterior  part  of  the  deep  concavity  of  the  metatarsus,  and  is  provided  with  a  proper 
sheath. 

Actions. — It  adducts  the  great  toe,  and  draws  the  head  of  the  metatarsal  bones  towards 
each  other. 

*  [The  terms  adductor  and  abductor  arc  applied  by  M.  Cruveilhier  to  the  muscles  of  the  great  toe,  from  their 
respective  actions  upon  it,  in  reference  to  the  axis  of  the  body  ;  the  muscle  attached  to  the  inner  side  of  that  toe 
being  called  its  adductor,  and  those  to  the  outer  side  its  abductors.  In  the  translation,  however,  the  nomen- 
clature of  Albinus  has  been  adopted,  in  which  the  terms  adductor  and  abductor  have  reference  to  the  axis  of 
the  limb :  first,  because  it  is  followed  by  the  majority  of  authors  ;  and,  secondly,  because  it  is  in  accordance 
with  the  principle  observed  by  M.  Cruveilhier  himself,  in  describing  not  only  all  the  muscles  of  the  hand,  but 
some  even  of  those  of  the  foot,  viz.,  the  interossei,  which  are  classed  by  him  as  abductors  or  adductors,  accord 
iug  as  they  draw  the  several  toes  from  or  towards  an  imaginary  axis  passing  through  the  second  toe.  By  this 
change  much  risk  of  perplexity  will  be  avoided,  and  a  uniform  principle  of  nomenclature  preserved  as  regards 
all  the  muscles  of  the  hand  and  foot. 

In  the  description  of  each  muscle  of  the  great  toe,  the  synonymes  of  Cruveilhier  are  given  between  brack 
ets  ;  but  in  all  instances,  both  here  and  hereafter,  where  these  muscles  have  incidentally  to  be  mentioned,  the 
names  adopted  from  Albinus  will  be  strictly  adhered  to. 

It  is  vcarccly  necessary  to  observe  that  the  abductor  of  the  little  toe  will  still  retain  its  name,  j 


THE    ABDUCTOR   DIGITI    MINIMI,  ETC. 


m 


External  Plantar  Region. 
The  Abductor  Digiti  Minimi. 

Dissection. — This  is  common  to  the  abductor  and  the  flexor  brevis.  The  first  is  ex- 
posed by  simply  removing  the  external  plantar  fascia,  and  the  second  by  removing  or  re- 
flecting down  the  first. 

The  abductor  digiti  minimi  (,v,fig.  131)  is  of  the  same  form,  the  saune  structure,  and  al- 
most the  same  size  as  the  abductor  pollicis,  and  extends  from  the  os  calcis  to  the  first 
phalanx  of  the  little  toe.  It  arises  by  tendinous  and  fleshy  fibres  from  the  external  pos- 
terior tuberosity  of  the  os  calcis,  from  the  outer  side  of  the  internal  posterior  tuberosity, 
and  from  an  aponeurosis  occupying  the  upper  surface  of  the  muscle.  The  fleshy  fibres 
having  arisen  in  succession  from  these  different  points,  proceed  obliquely  round  a  tendon, 
from  which  they  emerge,  opposite  the  posterior  extremity  of  the  fifth  metatarsal  bone. 
The  fleshy  belly  of  the  muscle  appears  to  end  at  this  point,  but  it  is  continued  by  other 
fibres,  arising  from  the  upper  surface  of  the  externd  plantar  fascia,  and  inserted  either 
into  the  common  tendon,  or  separately,  by  the  side  of  this  tendon,  into  the  outer  part  of 
the  first  phalanx  of  the  little  toe.  A  small  fleshy  bundle  is  frequently  detached  from  the 
body  of  the  muscle,  and  implanted  into  the  posterior  extremity  of  the  fifth  metatarsal 
bone,  together  with  a  prolongation  of  the  external  plantar  fascia,  which  serves  as  a  ten- 
don for  it. 

Action. — It  is  an  abductor  and  flexor  of  the  little  toe. 

The  Flexor  Brevis  Digiti  Minimi.  ^s- 133. 

This  is  a  small  fleshy  fasciculus  {x,figs.  131, 132, 133),  situ- 
ated along  the  external  border  of  the  fifth  metatarsal  bone,  and 
forming  a  continuation  of  the  series  of  interosseous  muscles, 
with  which  it  was  for  a  long  time  confounded  (interosseus, 
Spigelius) :  it  extends  from  the  second  row  of  the  tarsus,  and 
from  the  fifth  metatarsal  bone,  to  the  first  phalanx  of  the  little 
toe.  It  arises  from  the  ligamentous  layer  covering  the  plantai 
surface  of  the  metatarsal  row  of  the  tarsal  bones,  and  from  the 
posterior  extremity  of  the  fifth  metatarsal  bone  ;  it  is  inserted 
into  the  outer  side  of  the  first  phalanx  of  the  little  toe,  or,  more 
correctly,  into  the  posterior  edge  of  the  glenoid  ligament  of  the 
metatarso-phalangal  articulation  of  that  toe.  Some  of  the 
fleshy  fibres  will  be  found  attached  to  the  entire  length  of  the 
externjd  border  of  the  fifth  metatarsal  bone  ;  and  these  some- 
times form  a  small  and  very  distinct  muscle,  representing  the 
opponens  digiti  minimi  of  the  hand. 

Relations. — It  is  covered  below  by  the  plantar  fascia,  which 
is  here  very  thin,  and  also  by  the  tendon  of  the  abductor  digiti 
minimi ;  it  is  in  relation  above  with  the  fifth  metatarsal  bone 
and  the  first  plantar  interosseous  muscle. 

Action. — The  same  as  that  of  the  preceding  muscle  with  re- 
gard to  flexion,  but  its  action  is  less  powerful  and  less  exten- 
sive. 

Middle  Plantar  Region. 
The  Flexor  Brevis  Digitorum. 

Dissection. — Remove  the  plantar  fascia,  which  is  intimately  united  to  this  muscle  pos- 
teriorly. 

The  flexor  brevis  digitorum  {y,fig.  131)  is  a  short,  thick  muscle,  narrow  behind,  and' 
divided  into  four  tendons  in  front.  It  arises  from  the  inside  of  the  external  tuberosity 
of  the  OS  calcis,  from  the  upper  surface  of  the  middle  plantar  fascia,  from  a  special  ten- 
dinous expansion  occupying  the  lower  surface  of  the  muscle,  and  appearing  to  be  a  de- 
pendance  of  the  plantar  fascia ;  and,  lastly,  from  an  aponeurotic  septum,  situated  between 
Ti.  and  the  muscles  of  the  external  plantar  region.  It  forms  a  fleshy  belly,  which  is  nar- 
row and  thick  behind,  passes  directly  forward,  increases  in  breadth,  and  soon  divides 
into  four,  sometimes  only  into  three  fasciculi,  constituting  as  many  small  and  perfectly 
distinct  penniform  muscles,  the  long  and  delicate  tendons  of  which  emerge  from  the 
fleshy  fibres  before  reaching  the  metatarso-phalangal  articulations,  become  flattened,  and 
are  then  situated  below  and  in  the  same  sheath  with  the  tendons  of  the  flexor  longus. 
Opposite  the  first  phalanx  each  tendon  of  the  short  flexor  bifurcates,  to  allow  the  passage 
of  the  corresponding  tendon  of  the  flexor  longus,  is  formed  into  a  groove,  becomes  re- 
united above  the  latter  tendon,  and  once  more  bifurcates,  in  order  to  be  inserted  along 
the  borders  of  the  second  phalanx  (hence  it  was  named  perforatus  by  Spigelius,  and  le 
perfore  du  pied  by  Winslow).  The  short  flexor  of  the  toes  is,  therefore,  analogous  to  the 
superficial  flexor  of  the  fingers. 

Relations. — It  is  covered  below  by  the  plantar  fascia  and  the  skin  ;  it  is  in  relation 

Oo 


;20O  MYOLOGY. 

above  with  the  plantar  vessels  and  nprves,  with  the  tendon  of  the  flexor  longus  digitorum, 
and  with  the  flexor  accessorius  and  the  lumbricales,  from  which  it  is  separated  by  a  tendi- 
nous lamina.  On  its  outer  and  inner  side  it  is  completely  isolated  from  all  the  adjacent 
muscles  by  prolongations  of  the  plantar  fascia. 

Action. — It  flexes  the  second  phalanges  of  the  last  four  toes  upon  the  first  phalanges, 
and  these  upon  the  corresponding  metatarsal  bones. 

The  Flexor  Accessorius. 

This  is  a  flat,  quadrilateral  muscle,  forming  a  considerable  fleshy  mass  (massa  carnea, 
Jacobi  Sylvii,  z,fig.  132) ;  it  arises,  by  a  bifurcated  extremity,  from  the  lower  part  of  the 
groove  of  the  os  calcis,  and  a  small  part  of  the  calcaneo-scaphoid  ligament  by  fleshy 
fibres,  and  by  means  of  a  tendon  from  the  lower  surface  of  the  same  bone,  this  tendon 
sometimes  extending  as  far  as  the  external  posterior  tuberosity  of  the  os  calcis.  From 
these  points  the  fleshy  fibres  pass  directly  forward,  and  terminate  in  the  following  man- 
ner :  the  lower  fibres  become  inserted  into  the  outer  margin,  and  a  small  portion  of  the 
inferior  surface  of  the  tendon  of  the  flexor  longus  digitorum  ;  while  the  upper  are  inserted 
into  several  small  fibrous  bundles,  which  unite  together,  receive  a  considerable  expan- 
sion from  the  tendon  of  the  flexor  longus  poUicis,  and  are  ultimately  blended  with,  and 
increase  the  size  of  the  divided  tendon  of  the  flexor  longus  digitorum. 

Relations. — This  muscle  is  in  relation  below  with  the  flexor  longus  digitorum  and  the 
plantar  vessels  and  nerves,  and  abme  with  the  os  calcis  and  the  inferior  calcaneo-cuboid 
ligaments. 

Action. — It  is  a  muscle  of  re-enforcement,  and  assists  in  flexing  the  toes  ;  from  its  obli- 
quity, it  rectifies  the  oblique  action  of  the  flexor  longus  digitorum  in  the  opposite  direction. 

The  Lumbricales. 

The  lumbricales  Q,  I,  figs.  131,  132),  which  form  a  second  class  of  accessory  muscles 
belonging  to  the  flexor  longus  digitorum,  exactly  resemble  the  lumbricales  of  the  fingers  ; 
they  consist  of  four  small  fleshy  tongues,  decreasing  in  size  from  within  outward,  the  two 
outer  of  which  are  not  unfrequently  atrophied  ;  they  extend  from  the  angles  formed  by 
the  division  of  the  tendons  of  the  flexor  longus  to  the  inner  or  tibial  borders  of  the  first 
phalanges  of  the  last  four  toes,  and  to  the  corresponding  margins  of  the  extensor  tendons. 
They  are  distinguished  by  the  numerical  names  of  first,  second,  third,  and  fourth.  The 
first  is  situated  parallel  with  the  flexor  tendon  of  the  second  toe. 

Relations. — They  are  covered  below  by  the  flexor  brevis  digitorum ;  they  emerge  from 
beneath  the  plantar  fascia,  in  the  interval  between  the  sheaths  furnished  by  it  to  the 
flexor  tendons,  gain  the  inner  side  of  the  corresponding  metatarso-phalangal  articulation, 
and  terminate  upon  the  first  phalanx  and  inner  margin  of  the  tendons  of  the  extensor 
longus  digitorum.    They  have  the  same  action  as  the  lumbricales  of  the  hand. 

Interosseous  Region. 
The  Interossei. 
The  interosseous  muscles  of  the  foot  correspond  exactly  with  those  of  the  hand,  and 
require  the  same  consideration. 

They  arise  from  the  lateral  surfaces  of  the  interosseous  spaces  in  which  they  are 
placed ;  and  are  inserted  into  the  sides  of  the  first  phalanges  and  the  corresponding  mar- 
j^.  133.  gins  of  the  tendons  of  the  extensor  muscles.     They  are  seven  in 

number,  viz.,  four  dorsal  (three  of  which  are  seen  at  d  d  d,  fig. 
133),  and  three  plantar  {p  j)  p);  to  the  latter,  however,  the  ob- 
lique adductor  of  the  great  toe  may  be  added,  for  it  is  nothing 
more  than  a  very  large  plantar  interosseous  muscle. 

As  in  the  hand,  the  dorsal  interossei  are  abductors,  their  origins 
being  situated  externally  to  the  axis  of  the  foot ;  the  plantar  inter- 
ossei, again,  are  adductors ;  but  the  axis  of  the  foot  must  be  suppo- 
sed to  extend  through  the  second,  and  not  through  the  middle  toe. 
As  we  observed  in  the  hand,  the  dorsal  interossei  project  into  the 
plantar  region,  by  the  side  of  the  plantar  muscles  ;  and  so  narrow 
are  the  interosseous  spaces  in  the  foot,  that  these  dorsal  muscles 
are  much  more  completely  situated  in  tlie  plantar  than  those  of  the 
hand  in  the  palmar  region.  The  palmar  interossei  correspond- 
ing to  the  fourth  and  fifth  toes,  arise  not  only  from  the  lower  two 
thirds  of  the  internal  or  tibial  side  of  the  corresponding  metatar- 
7"  sal  bone,  but  also  from  the  lower  surface  of  the  posterior  extrem- 
ity of  the  same  bone.  It  follows,  therefore,  that  the  interosseous 
muscles,  viewed  from  below,  appear  one  continuous  muscle,  in 
which  it  would  be  difficult  to  separate  the  muscles  of  each  space, 
if  the  interosseous  plantar  fascia  did  not  give  off  prolongations 
between  them ;  elsewhere,  a  cellular  line  defines  the  limit  be- 
tween each  plantar  and  dorsal  muscle. 


PHYSIOLOGICAL   ARRANGEMENT    OF   THE    MUSCLES. 

Again,  as  in  the  hand,  the  dorsal  interossei  arise  from  two  corresponding  metatarsal 
bi)nes  at  once,  but  more  especially  from  the  lateral  surface  of  that  metatarsal  bone  which 
is  directed/rota  the  axis  of  the  foot :  as  in  the  hand,  also,  their  posterior  extremities  are 
perforated  by  the  posterior  perforating  arteries,  the  first  being  perforated  by  the  arteria 
dorsalis  pedis.  The  plantar  interossei  arise  from  only  one  of  the  metatarsal  bofnes,  and 
from  the  lateral  surface  that  is  directed  towards  the  imaginary  axis  of  the  foot ;  moreover, 
they  do  not  arise  from  the  entire  thickness  of  the  bone,  but  only  from  its  inferior  two 
thirds,  since  the  upper  third  is  covered  by  the  dorsal  muscle. 

The  following  are  the  general  relations  of  the  interossei :  they  are  separated  above 
from  the  tendons  of  the  extensors  by  a  layer  of  fibrous  tissue,  and  by  the  dorsal  inter- 
osseous fascia ;  and  below  from  the  proper  muscles  of  the  foot,  by  the  deep  plantar  in- 
terosseous fascia,  which  is  much  stronger  than  the  corresponding  structure  in  the  hand, 
and  gives  off  septa  between  the  different  pairs  of  interosseous  muscles. 


PHYSIOLOGICAL  ARRANGEMENT  OF  THE  MUSCLES. 

However  important  it  may  be  to  become  acquainted  with  the  order  of  super-imposi- 
tion, or  the  topographical  arrangement  of  the  muscles,  it  is  no  less  necessary  to  study 
the  retrospective  uses,  in  other  words,  the  physiological  arrangement  of  these  organs* 
In  order  to  obtain,  as  much  as  possible,  the  advantages  of  each  of  these  two  methods, 
having  already  described  each  muscle  in  its  topographical  order,  I  shall  now  give  a  table 
of  the  muscles,  arranged  according  to  their  physiological  relations.  It  is  important  to 
observe  that  the  terms  muscles  of  the  arm,  of  the  thigh,  <fc.,  have  not  the  same  accepta- 
tion in  the  two  arrangements.  Thus,  by  the  term  muscles  of  the  £irm,  in  the  topographi 
ical  order,  we  mean  the  muscles  which  occupy  the  region  of  the  arm,  as  the  deltoid,  bi- 
ceps, &c. ;  but,  in  the  physiological  arrangement,  the  same  term  is  applied  to  the  mus- 
cles which  move  the  arm,  viz.,  the  pectoralis  major,  latissimus  dorsi,  &c. 

Muscles  of  the  Vertebro-cranial  Column. 

These  are  divided  into  the  extensors,  the  flexors,  and  the  lateral  muscles  or  lateral 
flexors,  which  incline  the  vertebral  column  to  one  side  or  the  other.  There  are  no  rota- 
tors, for  rotation  is  performed  by  the  extensor  muscles. 

Extensors. — These  occupy  the  posterior  region  of  the  vertebral  column.  They  con- 
sist, on  each  side,  of,  1.  The  posterior  spinal,  or  long  muscles  of  the  back,  divided  into 
the  sacro-lumbalis,  longissimus  dorsi,  and  transverso-spinalis ;  2.  Of  the  transversalis 
colli  and  the  trachelo-mastoideus,  which  may  be  regarded  as  accessory  fasciculi  to  the 
longissimus  dorsi ;  3.  Of  the  splenius,  or  representative  of  the  longissimus  dorsi  of  the 
neck  and  head ;  4.  Of  the  complexus,  or  transverso-spinalis  of  the  head ;  5.  Of  the  m- 
ter-spinales,  in  which  the  two  recti  postici  of  the  head  may  be  included  ;  6.  Of  the  ob- 
liquus  major,  or  spino-transversalis  of  the  atlas  ;  7.  Of  the  obliquus  minor,  or  transverse 
spinalis  of  the  head. 

Flexors. — These  are  situated  on  the  anterior  region  of  the  vertebro-cranial  column. 
The  most  important  of  these  muscles  are  carried  forward,  and  attached  to  the  sternum, 
and  to  those  long  transverse  processes  called  the  ribs.  They  are  on  each  side,  1.  The 
rectus  abdominis ;  2.  The  stemo-cleido-mastoideus.  The  other  muscles  that  co-operate 
in  flexion  occupy  the  deep  anterior  cervical  region,  viz.,  1.  The  rectus  capitis  auticus 
major ;  2.  The  rectus  capitis  anticus  minor ;  3.  The  longus  colli. 

Lateral  Muscles. — These  are,  1.  The  inter-transversales  oCthe  neck  and  loins,  among 
which  I  include  the  rectus  capitis  lateralis  ;  2.  The  scaleni  anticus  et  posticus ;  3.  The 
quadratus  lumborum. 

Muscles  of  the  Ribs,  or  of  the  Thoracico-abdominal  Parietes. 
These  are,  1.  The  inter-costales,  externi  and  intemi,  which  are  both  elevators  and 
depressors;  2.  The  small  accessory  muscles,  viz.,  the  infra-costales  of  Verheyen  and 
the  supra-costales,  or  levatores  costarum,  the  latter  being  always  elevators ;  3.  The  ser- 
rati  postici  superiores,  which  are  elevators ;  4.  The  serrati  postici  inferiores,  depressors ; 
5.  The  triangularis  stemi,  or  small  anterior  serratus,  also  a  depressor ;  6.  The  diaphragm, 
a  muscular  septum,  the  contraction  of  which  increases  the  vertical  diameter  of  the  tho- 
riix,  and  draws  the  ribs  inward.  Tlie  muscles  of  the  abdominal  parietes  are  so  intimate- 
ly connected  in  action  with  those  of  the  thorax,  that  the  description  of  the  former  nat- 
urally follows  that  of  the  latter.  The  abdominal  muscles,  then,  may  be  regarded  as  mus- 
cles of  expiration,  and  are  all  depressors  of  the  ribs.     There  are,  1.  The  obliqims  exter- 

*  Custom,  rather  thtn  conviction,  has  induced  me  to  prefer  the  topographical  to  the  physiological  arrange- 
ment. The  only  objection  which  can  be  nrped  against  the  latter  is,  that  it  does  not  permit  all  the  muscles 
to  be  dissected  upon  the  same  subject  ;  but  this  objection  applies  only  to  a  few  regions  ;  and  as  these  regions 
exist  in  pairs,  the  superficial  muscles  on  one  side  might  surely  be  sacrificed.  Moreover,  there  is  no  reason 
why  the  examination  of  the  deep-seated  muscles  should  not  be  postponed  until  the  superficial  ones  have  been 
studied.  I  therefore  direct  students  to  dissect  these  parts  sometimes  according-  to  their  topographical,  and 
at  others  after  their  physiological  order 


fSffSt  MYOLOGY. 

nus,  which  is  nothing  more  than  a  large  external  intercostal  muscle,  extending  between 
the  ribs  and  the  pelvis ;  2.  The  obliquus  internus,  which  may  be  regarded  as  a  large 
internal  intercostal  muscle,  of  which  the  cremaster  is  a  dependance  ;  3.  The  trai  sversa- 
lis,  which  we  may  consider  as  forming  with  the  diaphragm  a  single  muscle,  intermpted 
by  its  costal  attachments. 

Muscles  which  move  the  Lower  Jaw. 
As  the  bones  of  the  upper  jaw  are  immovably  articulated  together  and  to  the  cranium, 
they  have  no  proper  muscles.  The  muscles  of  the  face  do  not  belong  to  them,  but  are 
true  cutaneous  muscles,  attached  to  the  different  bones  only  for  the  purpose  of  having 
fixed  origins.  The  lower  jaw,  on  the  contrary,  is  provided  with  two  principal  orders  of 
muscles,  elevators  and  depressors,  to  which  are  added  diductors  (from  diduco,  to  draw  aside). 
The  elevators  and  diductors  preponderate  ;  the  only  office  of  the  depressors  is  to  bring 
down  the  jaw  into  a  position  from  which  it  may  then  be  raised. 

1.  Elevators. — These  are  the  masseters,  the  temporales,  and  the  pterygoidei  interni. 

2.  Diductors,  viz.,  the  pterygoidei  extemi. 

3.  Depressors,  consisting  of  the  muscles  of  the  supra-  and  infra-hyoid  regions,  and 
more  particularly  of  the  two  digastrici. 

Muscles  which  move  the  Os  Hyoides. 

These  are  divined  into  elevators  and  depressors. 

All  the  elevators  belong  to  the  supra-hyoid  region,  and  are,  1.  The  stylo-hyoidei ;  2. 
The  mylo-hyoidei ;  3.  The  genio-hyoidei. 

The  depressors  consist  of  the  muscles  of  the  infra-hyoid  region,  viz.,  1.  The  sterno- 
hyoidei ;  2.  The  stemo-thyroidei ;  3.  The  thyro-hyoidei ;  4.  The  omo-hyoidei. 

Muscles  which  move  the  Pelvis. 
There  are  no  muscles  proper  to  the  pelvis.  The  ischio-coccygeus  is  the  only  intrinsic 
muscle.  The  extrinsic  muscles  attached  to  the  pelvis  do  not  belong  to  its  cavity,  but 
merely  take  their  fixed  points  from  its  parietes.  It  is  only  under  particular  circumstan- 
ces that  the  pelvis  changes  its  usual  office,  and  becomes  the  movable  point ;  for  exam- 
ple, in  the  horizontal  position,  in  the  action  of  climbing,  and  in  the  reversed  attitude  of 
a  tumbler,  the  pelvis  is  moved  upon  the  vertebral  column  on  the  one  hand,  and  upon  the 
femur  on  the  other. 

Muscles  which  move  the  Shoulder. 
Tlie  muscles  of  each  shoulder  are  divided  into  elevators  and  depressors,  both  of  which 
are  also  rotators.  The  elevators  are,  1.  The  trapezius  ;  2.  The  rhomboideus  ;  3.  The 
levator  anguli  scapulae.  The  depressors  are,  1.  The  pectoralis  minor ;  2.  The  subclavius  ; 
3.  The  serratus  magnus.  The  elevators  and  depressors  of  the  entire  shoulder  must  be 
carefully  distinguished  from  those  which  raise' or  depress  its  apex. 

Muscles  which  move  the  Thigh  upon  the  Pelvis. 

Tliese  muscles  are  divided  into  extensors,  flexors,  adductors,  abductors,  and  rotators 

The  extensors  and  abductors  are  the  same,  viz.,  the  three  glutaei. 

The  conjoined  psoas  magnus,  iliacus,  and  psoas  parvus  constitute  the  only_^xor. 

Adduction  is  performed  by  four  muscles,  viz.,  the  pectineus  and  the  three  adductors. 

Rotation  outward  is  performed  by  six  muscles,  viz.,  the  pyriformis,  the  two  gemelli,  the 
obturator  internus,  the  quaflratus  femoris,  and  the  obturator  externus. 

Rotation  inward  is  performed  by  the  tensor  vaginae  femoris,  and  especially  by  the  an 
terior  fibres  of  the  glutaei,  medius  et  minimus. 

Muscles  which  move  the  .Mrm  upon  the  Shoulder. 

These  muscles  are  divided  into  abductors,  which  are  at  the  same  iivae  flexors,  and  into 
adductors  and  rotators.  There  are  no  proper  muscles  for  the  movement  forward  or  flexion, 
nor  for  the  movement  backward  or  extension,  both  of  which  motions  are  effected  by  the 
adductors  and  abductors. 

The  abductors  are,  1.  The  deltoideus ;  2.  The  coraco-brachialis ;  3.  The  supra-spi- 
natus. 

The  adductors  are,  1.  The  pectoralis  major ;  2.  The  latissimus  dorsi ;  3.  The  teres 
major. 

The  rotators  are,  1.  The  external,  viz.,  the  infra-spinatus  and  the  teres  minor  ;  2.  The 
internal,  viz.,  the  sub-scapularis. 

Muscles  which  move  the  Leg  upon  the  Thigh. 

These  are  divided  into  flexors  and  extensors.  The  flexors  are,  1.  The  biceps  femoris ; 
2.  The  semi-tendinosus  ;  3.  The  semi-membranosus  ;  4.  The  popliteus  ;  5.  The  sarto- 
rius  ;  6.  The  gracihs. 

Extension  is  performed  by  one  muscle  only,  viz.,  the  triceps  femoralis,  the  long  head 


PHYSIOLOGICAL    ARRANGEMENT    OF   THE    MUSCLES. 

of  which  is  fonned  by  the  rectus  femoris,  and  the  other  two  heads  by  the  triceps  cruris 
of  authors,  viz.,  the  vastus  externus  and  vastus  internus,  including  the  crureus. 

I  should  remark,  that  all  these  muscles  which  arise  from  the  pelvis  perform  the  double 
function  of  moving  the  leg  upon  the  thigh,  and  the  thigh  upon  the  pelvis. 

Muscles  which  move  the  Forearm  upon  the  Arm. 
These  are  divided  into  flexors  and  extensors.     The  flexors  are  the  biceps  and  the 
brachialis  anticus.     The  extensors  are,  1.  The  triceps  (of  which  the  long  head  resembles 
the  rectus  femoris) ;  2.  The  anconeus. 

Muscles  which  move  the  Radius  upon  the  Ulna. 
These  are  rotators  inward,  or  pronators,  viz.,  1.  The  pronator  teres  ;  2.  The  pronator 
quadratus;  and  rotators  outward,  or  supinators,  viz.,  1.  The  supinator  longus ;  2.  The 
supinator  brevis.     The  pronators  occupy  the  anterior  region,  the  supinators  the  poste- 
rior region  of  the  forearm. 

Muscles  which  move  the  Hand  upon  the  Forearm. 

These  are  divided  into  flexors  and  extensors.  The  flexors  are,  1.  The  flexor  carpi 
radialis  ;  2.  The  palmaris  longus ;  3.  The  flexor  carpi  ulnaris.  The  extensors  are,  1. 
The  extensores  carpi  radiales,  longior  et  brevior ;  2.  The  extensor  carpi  ulnaris. 

Adduction  and  abduction  are  also  performed  by  these  muscles. 

Muscles  which  move  the  Fingers. 

These  are  divided  into  extensors,  flexors,  adductors,  and  abductors.  The  extensors 
are,  1.  The  extensor  communis  digitorum;  2.  The  extensor  digiti  minimi;  3.  The  ab- 
ductor longus  pollicis ;  4  and  5.  The  extensor  brevis  and  extensor  longus  pollicis ;  6. 
The  extensor  proprius  indicis. 

The  flexors  are,  1.  The  flexor  sublimis  digitorum  ;  2.  The  flexor  profundus  digitorum, 
and  its  accessories,  the  lumbricales  ;  3.  The  flexor  longus  pollicis. 

The  extensors  and  the  flexors  of  the  fingers  are  all  situated  in  the  forearm  ;  the  ad- 
ductors and  abductors  belong  to  the  hand  :  they  consist  of  the  interossei,  which  are  seven 
in  number,  four  dorsal,  constituting  the  abductors,  and  three  palmar,  which  are  adductors. 

Other  muscles  are  also  superadded  to  the  thumb  and  the  little  finger;  The  muscles 
superadded  to  the  thumb  are,  1.  Those  which  constitute  the  thenar  eminence  (ball  of 
the  thumb),  viz.,  the  abductor  brevis,  the  opponens,  and  the  flexor  brevis  ;  2.  The  ad- 
ductor pollicis,  which  is  nothing  more  than  a  palmar  interosseous  muscle.  The  mus- 
cles su|)eradded  to  the  little  finger  constitute  the  hypothenar  eminence  (ball  of  the  little 
finger),  and  form,  as  it  were,  a  repetition  of  those  of  the  thenar  eminence,  viz.,  the  ab- 
ductor brevis,  the  flexor  brevis,  and  opponens.  But  although  three  only  are  thus  de- 
scribed, it  is  because  the  palmar  interosseous  muscle  of  the  little  finger,  which  repre- 
sents the  adductor  poUicia,  presents  no  peculiarities,  and  is,  therefore,  classed  with  the 
other  palmar  interossei. 

Muscles  which  move  the  Foot  upon  the  Leg. 

These  are  divided  into  flexors  and  extensors  :  the  same  muscles  also  produce,  at  the 
articulation  of  the  two  rows  of  the  tarsal  bones,  movements  of  rotation,  which  corre- 
spond to  adduction  and  abduction. 

The  extensors  are,  1.  The  gastrocnemius  and  soleus,  or  the  triceps  suralis,  with  which 
we  describe  a  small  rudimentary  muscle,  the  plantaris.  2.  The  tibialis  posticus.  3.  The 
peroneus  longus  et  brevis. 

There  is  only  one  flexor,  viz.,  the  tibialis  anticus.  The  peroneus  tertius,  when  it  ex- 
ists, is  merely  a  dependance  of  the  extensor  longus  digitorum. 

There  are  no  muscles  in  the  leg  analogous  to  the  pronators  and  supinators  of  the  fore- 
arm. 

Muscles  which  move  the  Toes. 

These  are  divided  into  extensors  and  flexors. 

The  extensors  are,  1.  The  conjoined  extensor  longus  digitorum  and  peroneus  tertius. 
2.  The  extensor  proprius  pollicis.  3.  The  extensor  brevis  digitorum.  The  flexors  are,  1. 
The  flexor  longus  digitorum,  and  its  accessories,  the  lumbricales.  2.  The  flexor  brevis 
digitorum ;  the  flexor  longus  pollicis. 

Contrary  to  what  we  have  seen  with  regard  to  the  fingers,  many  of  the  flexors  and  ex- 
tensors of  the  toes  form  part  of  the  intrinsic  muscles  of  the  foot.  As  in  the  hand,  the  ad- 
ductors and  abductors  of  the  toes  occupy  the  thenar,  hypothenar,  and  interosseous  regions. 

The  interosseous  muscles  are  adductors  and  abductors  of  the  toes  ;  they  are  seven  in 
number,  four  dorsal,  being  the  abductors,  and  three  plantar,  acting  as  adductors. 

The  superadded  muscles  of  the  great  toe  are,  1.  The  muscles  of  the  thenar  eminence, 
viz.,  the  abductor  brevis  and  the  flexor  brevis.  2.  The  adductor  obliquus,  and  the  ad- 
ductor transversus.  The  muscles  superadded  to  the  little  toe  are  the  muscles  of  the  hy- 
pothenar eminence,  viz.,  the  abductor  and  the  flexor  brevis. 


APONEUROLOGY. 

Cutaneous  Muscles, 

These  muscles,  which  are  inserted  into  the  skin  by  one  of  their  ecxtremities  at  least, 
are  in  the  human  subject  concentrated  round  the  openings  in  the  face,  with  a  single  ex- 
ception, viz.,  the  palmaris  brevis. 

The  cutaneous  muscles  of  the  ear  belong  to  the  orifice  of  the  external  auditory  meatus, 
and  are  £ill  rudimentary  in  man.     They  form  the  three  auricular  muscles. 

The  muscles  of  the  eyelids,  on  either  side  of  the  face,  are  divided  into  constrictors  and 
dilators.  There  is  only  one  constrictor,  the  orbicularis  palpebrarum,  of  which  the  comi- 
gator  supercihi  may  be  considered  an  accessory. 

There  are  two  dilators,  viz.,  the  levator  palpebrae  superioris  and  the  occipito-frontalis. 

The  cutaneous  muscles  of  the  nose  consist  of  four  or  five  pairs,  i.  e.,  on  each  side  of  the 
face,  of  the  pyramidalis  nasi,  the  levator  labii  superioris  alaeque  nasi,  the  transversalis 
nasi,  the  depressor  alae  nasi  or  myrtiformis,  and  the  naso-labialis  of  Albinus. 

The  cutaneous  muscles  of  the  lips  are,  1.  A  constrictor,  viz.,  the  orbicularis  oris.  2. 
Nine  pairs  of  dilators,  consisting,  on  each  side,  of  the  levator  labii  superioris  alaeque  nasi 
already  mentioned,  the  levator  labii  superioris,  the  zygomaticus  major,  the  caninus,  the 
buccinator,  the  triangularis  oris,  the  quadratus  menti,  the  levator  labii  inferioris,  the  pla 
tysma  myoides ;  and  often  of  two  accessory  muscles,  viz.,  the  risorius  of  Santorini,  and 
the  zygomaticus  minor. 


APONEUROLOGY. 

General  Observations  on  the  Aponeuroses. — Structure. — Uses. 

The  aponeuroses  are  fibrous  membranes,  arranged  in  the  form  of  inextensible  textures, 
which  constitute  sheaths  for  the  muscles,  and,  at  the  same  time,  afford  them  broad  sur- 
faces for  attachment.  The  aponeuroses  are  generally  known,  at  the  present  day,  by  the 
name  oi  fascia  {fascia,  a  band),  an  expression  which  was  at  first  appUed  exclusively  to 
the  strong,  broad  aponeurotic  band,  forming  the  termination  of  the  tensor  vaginae  femoris, 
and  part  of  the  fascia  lata  of  the  thigh. 

The  aponeuroses  constitute  important  adjuncts  to  the  system  of  locomotion.  They 
were  for  a  long  time  neglected,  or,  rather,  studied  independently  of  each  other,  and  then 
only  partially,  until  Bichat  gave  a  general  view  of  them,  in  his  division  of  the  fibrous  sys- 
tem, including  the  membranous  forms  of  that  tissue,  of  which  the  aponeuroses  form  the 
greatest  part. 

As  the  aponeuroses  have  now  become  the  object  of  numerous  researches,  and  even 
the  subject  of  some  special  treatises,*  I  have  considered  that  it  would  be  useful  to  offer 
a  description  of  all  the  aponeuroses  of  the  human  body  under  the  head  of  Aponeurology. 
This  grouping  together  of  analogous  parts  will  have  the  double  advantage  of  simplifying 
the  description  of  the  particular  aponeuroses,  by  making  them  elucidate  each  other,  and 
of  bringing  into  prominent  notice  a  system  of  organs,  the  study  of  which  is  generally  neg- 
lected in  anatomical  lectures. 

General  Observations. — The  aponeuroses  are  divided  by  Bichat  into  two  distinct  class- 
es, one  serving  for  the  insertion  of  muscles,  viz.,  the  aponeuroses  of  insertion  ;  the  other 
for  investing  or  containing  the  muscles,  called  the  investing  or  confining  aponeuroses. 
Many  aponeuroses  serve  both  these  purposes  at  the  same  time  ;  but,  in  general,  one  or 
the  other  function  predominates  in  each. 

The  aponeuroses  of  insertion^  are  subdivided  into  those  formed  by  the  expanded  con- 
tinuations of  tendons,  and  those  which  do  not  originate  in  tendons.  The  aponeuroses 
of  the  gastrocnemius  and  soleus  belong  to  the  first  class  ;  those  of  the  broad  muscles  of 
the  abdomen  are  examples  of  the  second :  in  the  latter  case,  the  aponeuroses  serve  both 
for  the  insertion  and  investment  of  the  muscles.  Sometimes  the  aponeurosis  occupies 
the  middle  of  a  muscle  ;  as,  for  example,  the  cordiform  tendon  of  the  diaphragm,  and  the 
aponeuroses  of  the  occipito-frontalis.  The  use  of  the  aponeuroses  of  insertion  evident- 
ly has  reference  to  the  great  number  of  muscular  fibres,  all  of  which  could  not  have  been 
attached  to  the  limited  superficies  of  the  skeleton. 

The  investing  aponeuroses  occasionally  form  a  sheath  for  the  entire  limb,  sometimes 
for  only  a  single  muscle,  and  at  others  for  several  muscles.  The  first  set  are  called  gen- 
eral, the  other  two  partial  aponeuroses. 

The  aponeuroses  are  found  not  only  in  the  extremities  where  they  perform  such  im- 
portant offices,  but  also  in  the  trunk.  As  a  general  rule,  wherever  there  exists  a  muscle 
fulfilling  any  special  purpose,  and  susceptible  of  displacement  during  its  contraction,  we 
find  an  aponeurosis,  or,  rather,  an  aponeurotic  sheath ;  and  the  thickness  of  this  sheath 
is  proportioned  to  the  length  and  strength  of  the  muscle,  and  especially  to  its  tendency 
to  displacement. 

*  Godman,  of  Philadelphia,  published  in  1824  a  special  work  upon  the  fascise  ;  and  Paillard  a  treatise  upOB 
the  aponeuroses  of  the  human  body  in  1827.  t  See  note,  p.  296. 


GENERAL   REMARKS    UPON    THE   APONEUROSES.  295 

Each  aponeurosis  presents  for  our  consideration  an  external  and  an  iTitemal  surface,  a 
superior  border  or  circumference,  sometimes  termed  its  origin,  and  an  inferior  border  or 
circumference,  sometimes  called  its  termination. 

1.  The  external  surface  of  the  general  investing  aponeuroses  is  in  contact  with  the  sub- 
cutaneous cellular  tissue,  from  which  it  is  separated  by  the  superficial  veins,  lymphatics, 
and  nerves.  The  skin  is  therefore  movable  upon  these  aponeuroses,  excepting  in  some 
situations,  as  in  the  palms  of  the  hands  and  soles  of  the  feet,  where  it  is  intimately  uni- 
ted to  the  fasciae  by  prolongations  from  the  inner  surface  of  the  cutis.  What,  indeed, 
would  be  the  consequences  with  regard  to  the  sense  of  touch,  or  in  the  attitude  of  stand- 
ing, if  the  skin  over  those  regions  were  as  movable  as  it  is  upon  the  thigh  1  The  same 
adhesion  is  also  observed  between  the  hairy  sc£dp  and  the  subjacent  aponeurosis. 

The  mobility  of  the  skin  upon  the  aponeuroses  depends  upon  the  following  contrivance : 
From  the  inner  surface  of  the  skin  are  given  off  a  great  number  of  prolongations,  which, 
having  intercepted  the  areolae  containing  the  adipose  tissue,  unite  together,  and  expand 
into  a  membrane,  which  glides  over  the  aponeuroses  and  the  superficial  vessels  and 
nerves  :  the  sub-cutaneous  membrane  thus  formed  bears,  the  name  of  the  fascia  superfici- 
alis :  it  is  only  distinctly  seen  in  regions  that  are  traversed  by  superficial  vessels  and 
nerves,  as  in  the  lower  part  of  the  abdomen,  and  on  the  extremities. 

2.  The  deep  surface  of  a  general  investing  aponeurosis  presents  fibrous  prolongations 
passing  between  the  different  layers  of  muscles,  and  even  between  the  muscles  of  which 
these  layers  are  composed.  Moreover,  this  surface  and  its  several  prolongations  some- 
times afford  attachments  to  the  superficial  muscles,  and  sometimes  it  glides  over  the  mus- 
cles and  their  tendons  by  means  of  a  very  loose  filamentous  cellular  tissue — an  arrange- 
ment that  prevails  throughout  the  greater  part  of  the  extent  of  this  surface.  Lastly, 
amid  aU  these  sheaths  for  the  muscles,  there  exists  a  proper  sheath  for  the  principal 
vessels  of  the  extremities. 

These  aponeurotic  sheaths  are  not  so  exactly  moulded  upon  the  muscles  as  not  to  ad- 
mit of  the  accumulation  of  a  certain  quantity  of  fat  in  their  interior ;  nevertheless,  their 
capacity  is  so  far  proportioned  to  the  size  of  the  muscles,  that  the  latter,  during  their 
contraction,  experience  a  degree  of  pressure  from  them  which  is  highly  favourable  to 
their  action,  at  the  same  time  that  it  prevents  all  displacement. 

In  emaciated  individuals,  these  sheaths  are  no  longer  filled  by  their  respective  mus- 
cles ;  and,  without  doubt,  the  want  of  a  due  compression  upon  the  muscles  has  some  in- 
fluence in  producing  the  weakness  experienced  by  convalescents,  or  by  those  wasted  by 
some  chronic  disease. 

3.  The  borders  or  circumferences  of  aponeuroses,  incorrectly  named  their  origin  and  ter- 
mination, are  either  continuous  with  the  aponeuroses  of  the  adjacent  regions,  or  are  at- 
tached to  the  processes  on  the  articular  extremities  of  the  bones,  or  result,  in  part,  from 
the  expansion  of  tendons. 

The  aponeuroses  are  perforated  by  vessels  and  nerves,  which,  in  such  cases,  are  gui- 
ded and  protected  by  arches,  rings,  or  canals  of  fibrous  tissue  :  of  this  nature  are  the 
sheaths  of  the  femoral  artery  and  vein,  and  of  the  brachial  artery  and  veins,  the  femoral 
arch,  the  canal  and  arch  of  the  adductor  muscles  of  the  thigh,  the  arch  of  the  obturator 
foramen,  and  the  aortic  arch  of  the  diaphragm ;  these  canals  and  arches  tend  to  prevent 
any  injury  to  the  vessels  and  nerves  by  which  they  are  traversed  during  the  contraction 
of  the  muscles.  We  must  not  suppose,  however,  that  the  vessels  are  exempt  from  all 
pressure  ;  for  experience  has  proved  that  arteries  are  particularly  liable  to  become  affect- 
ed with  aneurism  in  the  neighbourhood  of  such  arches  ;  as,  for  example,  the  popliteal  and 
femoral  arteries  and  the  aorta.  The  muscular  fibres,  in  fact,  are  not  attached  to  these 
arches  in  such  a  manner  as  to  dilate  them  in  all  directions  during  their  contraction,  but 
rather  in  such  a  way  as  to  elongate  them  in  one  direction  and  contract  them  in  another. 

All  the  aponeuroses,  whether  of  insertion  or  investment,  have  their  tensor  muscle. 
With  regard  to  the  aponeuroses  of  insertion,  this  requires  no  proof;  for  the  action  of  the 
muscle  or  muscles  to  which  they  afford  attachment  must  necessarily  render  them  tense. 
It  is  no  less  true,  however,  of  the  investing  aponeuroses,  some  of  which  have  even  a  sep- 
arate muscle  for  this  purpose.  Thus,  the  occipital  and  frontal  muscles  are  tensors  of  the 
occipito-frontal  aponeurosis.  The  fascia  lata  is  rendered  tense  by  the  tensor  vaginae  fe- 
moris,  the  palmar  fascia  by  the  palmaris  longus,  &c. 

The  aponeuroses  of  both  kinds  are  inextensible,  resisting,  and  insensible  membranes, 
their  thickness  and  strength  being  exactly  proportioned  to  the  resisting  power  and  strength 
of  the  muscles  which  are  invested  by  them,  or  to  which  they  afford  the  means  of  inser 
tion.  Thus,  the  fascia  of  the  thigh  is  very  much  stronger  than  that  of  the  arm  :  the  thick- 
ness of  the  aponeuroses  increases  from  the  upper  to  the  lower  part  of  the  limbs  ;  and, 
again,  the  powerful  vastus  externus  is  provided  with  a  much  stronger  sheath  than  the 
muscles  of  the  posterior,  or  of  the  internal  region  of  the  thigh.  We  may,  then,  consider 
it  as  a  general  law,  without  exception,  that  the  aponeurotic  system  invariably  presents  a 
corresponding  degree  of  development  to  that  of  the  muscular  system.  "VVe  should,  there 
fore,  study  the  aponeuroses,  as  well  as  the  muscles,  upon  robust  subjects  ;  their  pearly 
aspect  is  destroyed  in  individuals  wasted  by  chronic  diseases.     The  aponeurotic  and 


296  APONEUROLOGY. 

muscular  systems  are  both  most  fully  developed  in  carnivora,  in  which  class  of  animals 
the  pearly  appearance  is  peculiarly  well  marked,  and  the  cellular  tissue  is  often  replaced 
by  a  fibrous  texture  ;  a  transformation  which  proves  the  analogy  of  the  cellular  and  fibrous 
tissues  in  organization,  vitality,  and  function.* 

The  thinner  fasciae  are  composed  of  a  single  layer  of  parallel  fibres,  which  have  be- 
tween them  intervals  of  different  sizes  :  stronger  aponeuroses  are  composed  of  several 
planes,  the  fibres  of  which  intersect  each  other  at  various  angles.  The  vessels  and 
nerves  of  the  aponeuroses  are  little  known  ;  but  I  believe  that  I  have  traced  nerves  into 
them.     I  have  certainly  done  so  with  regard  to  the  dura  mater.* 

I  shall  include  among  the  aponeuroses  the  fibrous  sheaths  of  tendons,*  which  are  some- 
times presented  under  the  form  of  imperfect  rings,  or  canals  of  different  lengths,  which 
retain  the  tendons  in  contact  with  the  bones.  They  serve  to  confine  the  tendons,  to 
keep  them  applied  against  the  bones,  and  to  favour  their  reflection. 

The  periosteum*  must  also  be  annexed  to  the  aponeurotic  system  ;  it  is  a  tnie  aponeu- 
rosis, covering  every  part  of  the  bones,  and  constituting  a  fibrous  sheath  for  them.  We 
may  consider  the  periosteum  as  the  central  point  of  the  aponeurotic  system,  proceeding 
from  which,  we  find  either  tendons  expanding  upon  the  surface  or  in  the  substance  of 
muscles,  and  constituting  the  aponeuroses  of  insertion  ;  or  else  those  fibrous  cones  or  pyr- 
amids, from  the  interior  of  which  the  fleshy  fibres  take  their  origin.  From  the  perioste- 
um, or,  rather,  from  the  ridges  or  clefts  by  which  the  surfaces  of  bones  are  marked,  both 
the  partial  and  general  investing  aponeuroses  arise.  In  this  way  the  muscles  of  the  ex- 
tremities are  situated  between  two  fibrous  layers  ;  the  deep  layer  consisting  of  the  peri- 
osteum, the  superficial  layer  of  the  general  investing  fascia :  numerous  septa  pass  from 
one  to  the  other,  and  divide  the  limb  into  a  number  of  compartments,  intended  to  isolate, 
confine,  and  protect  the  different  muscles. 

Use  of  the  Aponeuroses. — Forming,  as  they  do,  an  important  division  of  the  fibrous  tex- 
tures, they  partake  of  the  physical,  chemical,  anatomical,  physiological,  and  pathological 
properties  of  that  tissue. 

1.  From  their  great  strength,  they  are  enabled  to  resist  the  powerful  traction  and  dis- 
tension exercised  upon  them  by  the  muscular  fibres.  Their  division  or  destruction  is 
accompanied  by  displacement  of  the  parts  which  they  are  intended  to  bind  down.  Be- 
tween the  different  layers  of  the  regions  of  the  body  they  establish  very  precise  limits,  a 
knowledge  of  which  is  of  the  greatest  importance,  in  enabling  us  accurately  to  accoxmt 
for  many  morbid  phenomena,  and  in  guiding  us  in  the  performance  of  surgical  operations. 

2.  They  are  inextensible  ;  hence  the  resistance  which  they  oppose  to  the  development 
of  subjacent  parts,  and  the  tension  produced  by  inflammation  of  organs  situated  beneath 
them.  They  yield  to  gradual  distension,  but  then  become  thinner  and  weaker,  and  can 
only  imperfectly  fulfil  their  proper  offices. 

3.  They  are  totally  inelastic,  and,  therefore,  when  distended  beyond  a  certain  point, 
never  return  to  their  original  dimensions.  Of  this  we  have  an  example  in  the  condition 
of  the  abdominal  parietes  after  utero-gestation,  or  ascites. 

4.  The  low  degree  of  vitality  they  possess  explains  why  they  are  so  slightly  involved 
in  inflammation  or  other  morbid  conditions  of  the  adjacent  structures,  and  also  the  fact 
of  their  establishing  limits  beyond  which  these  diseases  seldom  pass.  They  are  insen- 
sible to  all  ordinary  stimuli,  but  become  painful  when  they  are  violently  overstretched 
The  plantar  fascia,  under  such  circumstances,  becomes  extremely  sensitive. 

Having  made  these  general  remarks,  we  shaU  now  describe,  in  succession,  the  prin- 
cipal aponeuroses  of  the  human  body.f 

•  See  note,  infra. 

t  Note  on  Aponeurology. — [The  analogy  existing'  between  the  cellular  and  aponeurotic  investments  of  various 
organs  renders  it  advantageous  to  consider  in  this  place  the  general  a.n-Atomy  of  the  cellular  and  fibrous  tissues. 

The  ultimate  elements  of  both  these  kinds  of  tissue  are  precisely  similar,  though  somewhat  differently  ar- 
ranged in  each  ;  they  consist  of  delicate  transparent  filaments,  varying  in  diameter  from  ^^j-^  ^^^  th  to  yj^Tj-g^th 
of  an  inch,  and  having  a  peculiar  sinuous  or  undulating  direction ;  they  are  insoluble  in  cold  water,  but  by 
long-continued  boiling  are  almost  entirely  converted  into  gelatine. 

In  cellular  tissue  these  undulating  filaments  are  arranged  side  by  side,  either  into  larger  compound  and  flei- 
uous  fasciculi,  or  into  thin,  transparent  lamina,  which  cross  and  intersect  one  another  in  all  directions,  so  as 
to  lesve  interstitial  cavities  or  areolie,  freely  communicating  with  each  other,  and  moistened  by  an  albuminous 
fluid.  The  tissue  thus  formed,  more  properly  called  areolar,  or  filamentous,  is  of  a  grayish  aspect,  and  highly 
elastic  ;  the  latter  property  depending  not  on  any  innate  elasticity  in  the  ultimate  filaments,  but  on  the  sinuous 
disposition  of  those  filaments,  and  of  the  fasciculi  into  which  they  are  collected.  But  few  vessels,  and  still 
fewer  nerves,  are  believed  to  terminate  in  this  tissue.  It  is  continuous  over  the  whole  body  ;  hence  the  great 
extent  to  which  it  may  be  affected  with  diffuse  inflammation;  it  also  invests  and  isolates  parts,  forms  the  ma- 
trix of  nearly  all  organs,  and  the  basis  of  many  membrane* ;  and  is  called,  according  to  its  position,  investing, 
intermediate,  penetrating,  parenchymatous,  or  sub-membranous.  The  characters  above  described  are  most 
strongly  marked  in  the  loose  cellular  tissue,  examples  of  which  are  met  with  in  the  axilla,  under  the  sub-scap- 
ular muscle,  between  the  free  surfaces  of  muscles  and  their  sheaths,  behind  the  kidneys,  &c.  In  other  situ- 
ations it  is  more  condensed,  as  in  the  sub-serous,  sub-mucous,  and  snb-cutaneoiis  cellular  tissues  ;  in  the  latter 
of  these,  or  the  superficial  fascia,  and  also  in  the  cutis  itself,  it  approaches  to  the  fibrous  tissue  both  in  density 
and  in  the  mode  of  arrangement  of  its  elementary  filaments,  and  is  therefore  termed  fibro-cellular  tissue. 
From  this  variety  the  transition  is  natural  to  the  fibrous  tissues,  properly  so  called. 

\n  fibrous  tissue  the  undulating  primitive  filaments  are  also  arranged  side  by  side  into  fasciculi,  which  diflTer 
from  those  of  cellular  tissue  in  being  much  larger,  more  dense  and  more  opaque,  and  in  being  straight  in- 
stead of  flezuous.     They  are  white,  shining,  strong,  and  almost  inelastic,  qualities  depending  on  the  compact 


SUPERFICIAL    FASCIA.  297 

PARTICULAR  APONEUROSES. 
Superficial  Fascia. — Aponeuroses  of  the  Cranium — of  the  Face — of  the  Neck — of  the  Thorax 
— of  the  Abdomen — of  the  Pelvis — of  the  Thigh,  Leg,  and.  Foot — of  the  Shoulder,  Arm, 
Forearm,  and  Hand. 

The  Superficial  Aponeurosis,  or  Superficial  Fascia. 

From  every  point  of  the  deep  surface  of  the  skin  fibrous  cellular  lamellae  arise,  which 
intersect  each  other  in  various  directions,  so  as  to  form  meshes  or  areolae,  containing 
adipose  tissue  in  ordinary  circumstances,  and  a  serous  fluid  in  cedema.*  The  cutaneous 
muscle  (panniculus  carnosus)  of  the  lower  animals  is  developed  in  these  laminae  ;  and 
among  them  are  situated  the  sub-cutaneous  vessels  and  nerves,  and  the  l)TTiphatic  glands. 
The  name  oi  fascia  superficialis  has  been  of  late  applied  to  this  assemblage  of  lamellae. 

It  was  pointed  out  in  a  particular  manner  by  Ghsson,  who  described  it  under  the  name 
of  the  general  investment  of  the  muscles,  proceeding  from  the  spine,  and  covering  the 
whole  body;  Camper,  Cowper,  Scarpa,  Hesselbach,  Lawrence,  J.  Cloquet,  &c.,  have 
described  it  upon  the  abdomen,  in  its  relation  with  herniae  ;  Godman  has  spoken  of  its 
existence  over  the  entire  surface  of  the  body  :  M.  Paillard,  in  his  inaugural  dissertation, 
traced  it  with  still  greater  exactness  ;  MM.  Velpeau  and  Blandin,  in  their  Traites  d^Ana- 
tomie  Chirurgicale,  consider  it  as  existing  in  almost  all  regions  of  the  body. 

But  if  the  word  aponeurosis  be  employed  in  its  ordinary  acceptation,  it  will  be  found 
that  a  fascia  superficifilis,  consisting  of  a  fibrous  texture  capable  of  anatomical  demon- 
stration, exists  only  in  two  kinds  of  situations,  viz.,  in  those  where  the  skin  is  extreme- 
ly movable,  and  in  those  where  there  is  a  layer  of  sub-cutaneous  vessels  and  nerves  :  in 
both  these  cases  the  fibrous  prolongations  from  the  skin  are  expanded  into  a  thin  lamina, 
constituting  a  superficial  covering  for  these  vessels  and  nerves,  and  separated  from  the 
fibrous  investment  of  the  muscles  by  a  layer  of  cellular  and  adipose  tissue,  of  variable 
thickness.  In  all  other  parts,  the  fibro-cellular  prolongations  of  the  skin  become  contin- 
uous either  with  the  investing  aponeuroses,  or  with  the  proper  fibro-cellular  sheaths  of 
the  muscles,  or  are  lost  in  the  sub-cutaneous  cellular  tissue.  So  true  is  this,  that  this 
thin  areolar  layer,  which  can  with  difficulty  be  separated  from  the  skin  in  emaciated 
persons,  disappears  altogether  in  those  whose  cellular  tissue  is  distended  by  fat  or  se- 
rous effusion. 

Having  made  these  remarks,  I  shall  describe  the  superficial  fascia  in  those  regions 
only  where  it  can  be  easily  demonstrated,  viz.,  in  the  lower  part  of  the  abdomen,  and  in 
the  extremities.  « 

The  Superficial  Fascia  of  the  Abdomen. 

This  aponeurosis,  from  its  constituting  the  first  sub-cutaneous  covering  of  herniae,  has 
particularly  engaged  the  attention  of  authors  who  have  specially  treated  of  the  patho- 
logical anatomy  of  those  diseases. 

It  becomes  evident  in  the  neighbourhood  of  the  umbilical  region,  but  is  much  more  dis- 
tinct at  the  fold  of  the  groin,  where  it  divides  into  two  layers,  one  of  which  is  attached 
to  the  femoral  arch,  and  the  other  is  prolonged  upon  the  lower  extremity.  It  is  bound- 
ed on  the  inside  by  the  median  line,  and  on  the  outside  by  another  line,  extending  per- 
pendicularly upward  from  the  anterior  superior  spinous  process  of  the  ilium.  It  is  pro- 
longed over  the  inguinal  ring,  and  over  the  spermatic  cord  in  the  male  subject. 

parallel  disposition  of  the  component  filaments,  and  the  slight  amount  of  elasticily  in  particular  on  the  ab- 
sence of  sinuosity  in  the  compound  fasciculi.  According  to  the  manner  in  which  tliese  fasciculi  or  fibres  (as 
they  are  termed)  are  arranged  and  combined,  wo  have  either  the  membranous  or  the  fascicular  form  of  fibrous 
tissues. 

In  the  membranous  form  there  are  some  which  closely  resemble  the  fibro-cellular  memliranes  already  allu- 
ded to,  and  consist  of  the  shining  fibres  crossing  each  other  in  all  directions  (without  anastomosis),  and  inter-* 
mixed  with  more  or  less  condensed  cellular  tissue  ;  for  example,  the  thinner  investing  aponeurosis,  the  capsu- 
lar ligaments,  the  pericardium,  tunica  albuginea,  periosteum,  and  dura  mater.  In  others,  again,  the  fibres  are 
more  parallel,  though  still  intersected,  and  combined  with  cellular  tissue,  as  in  the  fascia  lata  of  the  thigh, 
and  in  other  strong  investing  aponeuroses.  In  the  aponeuroses  of  insertion  of  the  broad  muscles,  and  in  the 
expanded  terminations  of  tendons,  there  is  scarcely  any  cellular  tissue,  while  the  parallel  arrangement  is  yet 
more  perfect ;  and,  finally,  the  latter  attains  its  utmost  perfection  in  the  round  ligaments,  and  in  tendons, 
which  constitute  the  fascicular  form  of  fibrous  tissue,  and  the  type  of  the  tissue  itself. 

These  textures  contain  but  few  nenes  and  vessels.  The  distribution  of  a  branch  of  the  fourth  cranial  nerve 
to  the  dura  mater,  alluded  to  in  the  text,  has  been  confirmed  by  other  anatomists.  Bloodvessels  abound  in  the 
periosteum,  but  they  merely  divide  in  that  membrane,  so  as  to  enter  the  bone  at  a  great  numlier  of  points. 

The  sheaths  of  tendons  (classed  among  the  fibrous  tissues  by  M.  Cruveilhier)  display  a  tendency  to  become 
fibro-cartilaginous,  especially  at  and  near  their  attachments  to  the  bones.  They  have  fiitherto  been  described 
(ex.  gr.,  p.  250,  257)  as  if  lined  by  vaginal  synovial  membranes  (note,  p.  177).  According  to  Dr.  Ifenl6,  how- 
ever, their  interior  is  not  covered  by  an  epithelium.  The  bursa,  or  so-called  bursal  synovial  membranes,  formed 
between  the  tendons  of  muscles  (p.  265),  between  tendons  and  bones  (p.  265,  266,  267),  and  between  the  skin 
and  projecting  parts  of  bones,  as  over  the  patella,  the  olecranon,  <&c.,  according  to  the  same  authority,  are  also 
destitute  of  epithelium.  It  would  appear,  therefore,  that  although  these  cavities  resemble  in  function  the 
true  synovial  membranes,  they  differ  anatomically  from  them,  and  consist  merely  of  shut  sacs  formed  in  the 
Bfeneral  cellular  texture  of  the  liody.  Such  bursie,  however,  as  communicate  with  the  synovial  capsules  of 
oints  (p.  216.  244),  are  probably  lined  by  an  epithelium.] 

*  [AdipoKc  tissue  is  never  deposited  m  the  suli-cutaneous  tissue  of  the  eyelids,  nor  in  the  male  onjan  of  tfcn- 
«raliou.    These  lart",  however,  m-'V  liecoine  much  distended  from  serous  infiltration.] 

Pp 


APONEUROLOGY. 

It  has  been  said  that  in  the  foetus,  before  the  descent  of  the  testicle,  the  superficial  fas 
cia  dips  into  the  inguinal  canal,  and  forms  an  infundibuliform  prolongation,  reaching  up 
to  the  lower  part  of  that  gland  ;  and  the  dartos  has  been  supposed  to  result  from  the  ex- 
pansion of  this  fascia — a  description  which  can  be  regarded  only  as  an  ingenious  specu- 
lation, which  has  not  been  confirmed  by  actual  dissection. 

Lastly,  the  external  surface  of  the  superficial  fascia  of  the  abdomen  is  in  relation  with 
the  skin,  separated  from  it,  however,  by  a  layer  of  adipose  tissue  of  variable  thickness, 
in  which  the  sub-cutaneous  vessels  and  nerves  are  situated.  Its  deep  surface  corre- 
sponds with  the  aponeurosis  of  the  external  oblique  muscle,  and  with  a  portion  of  its 
fleshy  fibres  :  from  these  parts  it  is  separated  by  a  layer  of  serous  cellular  tissue,  which 
enables  it  to  be  moved  easily  upon  this  muscle  and  the  sub-cutaneous  vessels  and  nerves. 

The  Superficial  Fascia  of  the  Upper  and  Lower  Extremities. 

These  are  thin  fibrous  sheaths,  separated  from  the  skin  by  a  greater  or  less  quantity 

of  adipose  tissue,  and  from  the  investing  aooneurosis  of  the  muscles  by  the  sub-cutaneous 

vessels  and  nerves.     It  does  not  exist  around  the  joints,  nor  in  the  palms  of  the  hands 

and  soles  of  the  feet,  for  in  these  places  the  skin  adheres  to  the  subjacent  aponeuroses 

The  Aponeuroses  of  the  Cranium. 

The  Occipito-frorUal  or  Epi-cranial  Aponeurosis. 

This  is  a  sort  of  tendinous  or  cutaneous  cap  {galea  capitis),  stretched  between  the  two 
frontal  and  two  occipital  muscles.  Its  superficial  surface  is  intimately  adherent  to  the 
skin  by  means  of  very  short  and  strong  fibrous  prolongations,  between  which  the  fatty 
matter  is  deposited :  the  frontal,  occipital,  temporal,  and  auricular  vessels  and  nerves 
traverse  this  adipose  tissue.  Its  deep  surface  glides  upon  the  periosteum  of  the  scull 
(pericranium)  by  the  intervention  of  a  very  delicate  cellular  tissue,  in  which  fat  is  never 
found.  Its  anterior  margin  receives  the  fibres  of  the  frontal  muscles,  forming  a  trian- 
gular point  between  them ;  its  posterior  margin  receives  the  fibres  of  the  occipital  mus- 
cles, and  also  occupies  the  interval  between  them.  These  two  muscles  act  as  tensors 
of  the  aponeurosis.  Its  outer  margin  gives  attachment  to  the  superior  and  anterior- 
auricular  muscles.  It  is  composed  behind  of  shining  fibres,  which  seem  to  form  a  ten- 
don of  insertion  to  the  occipitalis  muscle,  but  it  soon  loses  its  pearly  appearance,  and 
becomes  more  adherent  to  the  skin  :  it  is  thick  and  strong  at  the  upper  part  of  the  head, 
but  thin  and  almost  cellular  at  the  sides  :  it  may  be  regarded  as  a  dependance  of  the  su- 
perficial fascia.  It  gives  rise  to  the  tension  which  is  so  common  and  so  dangerous  in 
inflammations  of  this  region.  Its  adhesion  to  the  skin  explains  the  shallow  character 
of  ulcers,  and  the  flatness  of  the  small  abscesses  occurring  in  these  parts. 

The  Temporal  Aponeurosis. 

Besides  the  tendinous  origin  of  the  temporal  muscle,  which  has  been  already  descri- 
bed, there  is  also  a  very  strong  investing  aponeurosis,  arising  from  the  upper  border  of 
the  zygomatic  arch,  and  inserted  into  the  curved  line  bounding  the  temporal  fossa  above. 
This  aponeurosis  completes  the  sort  of  case  in  which  the  muscle  is  contained  ;  and  the 
space  between  it  and  the  temporal  fossa  corresponds  with  the  thickness  of  the  muscle. 

It  differs  from  the  epicranial  aponeurosis,  which  is  more  superficial  and  covers  it  su- 
periorly, in  not  adhering  to  the  skin,  which  glides  very  easily  upon  it.  Its  deep  surface 
adheres  to  the  upper  part  of  the  muscle,  and  furnishes  it  with  numerous  points  of  at- 
tachment ;  below  it  becomes  free,  and  is  separated  from  the  fleshy  fibres  by  a  consider- 
able quantity  of  fat ;  hence  the  depression  formed  in  this  situation  in  emaciated  persons. 

It  increases  in  thickness  from  above  downward  ;  it  divides  below  into  two  layers  :  one 
superficial  and  thinner,  inserted  into  the  outer  edge  of  the  upper  border  of  the  zj^goma ; 
.the  other  deep  and  thicker,  attached  to  the  inner  surface  of  that  process.  In  tolerably 
stout  persons,  a  considerable  quantity  of  fat  is  situated  between  these  two  layers,  and  a 
remarkable  branch  of  the  temporal  artery  also  occupies  the  same  situation.  This  fat 
must  not  be  confounded  with  the  larger  mass  which  lies  beneath  the  aponeuroses.  The 
resistance  of  this  fascia  explains  the  reason  why  abscesses  in  the  temporal  fossa  never 
point  outward,  but  rather  tend  downward  into  the  zygomatic  fossa. 

The  Aponeuroses  of  the  Face. 

The  Parotid  Aponeurosis. 
This  is  a  sheath  of  great  thickness,  especially  that  part  which  covers  the  outer  surface 
of  the  gland  ;  it  is  continuous  below  with  the  cervical  fascia.  It  belongs  especially  to 
the  gland,  for  which  it  forms  a  framework  by  means  of  fibrous  prolongations  from  its 
deep  surface.  The  density  of  this  sheath  explains  both  the  pain  caused  by  inflammation  of 
the  gland,  and  the  difliculty  with  which  pus  makes  its  way  from  within  it  to  the  surface. 

The  Masseteric  Aponeurosis. 
This  is  a  thin  tendinous  layer  covering  the  masseter  muscle,  and  continuous  below 
with  the  cervical  fascia  ;  it  appears  to  divide  behind  into  two  layers,  one  of  which  con- 


THE    CERVICAJ.    FASCIA,    ETC.  ^99^ 

Stitntes  the  parotid  fascia,  and  the  other  penetrates  between  that  gland  and  the  tiasse- 
ter ;  above  and  anteriorly,  it  becomes  merged  into  the  cellular  tissue.  Purulent  matter 
situated  beneath  this  fascia  tends  downward  into  the  neck,  but  when  situated  superfi- 
cially to  it,  points  towards  the  skin. 

The  Buccinator  Aponeurosis. 
The  buccinator  is  covered  by  a  closely  adherent  fibrous  layer,  which  is  regarded  as  tne 
expansion  of  the  fibrous  sheath  of  the  Stenonian  duct ;  it  is  thickest  behind,  where  it  is 
termed  the  buccinato-pharyngeal  aponeurosis,  because  it  gives  attachment  behind  to  the 
superior  constrictor  of  the  pharynx,  and  to  the  buccinator  in  front.  This  aponeurosis 
prevents  superficial  abscesses  from  opening  into  the  mouth,  and  is  also  opposed  to  the 
extension  outward  of  diseases  attacking  the  mucous  membrane. 

The  Cervical  Aponeurosis,  or  Cervical  Fascia. 
In  the  cervical  region  we  find,  1.  The  cervical  fascia ;  2.  The  prevertebral  aponeurosis 

The  Cervical  Fascia. 

The  cervical  aponeurosis  covers  the  whole  anterior  region  of  the  neck ;  it  extends 
from  the  base  of  the  lower  jaw  to  the  sternum  and  clavicles,  and  is  insensibly  lost  on 
either  side  in  the  sub-cutaneous  cellular  tissue.  It  is  thick  in  the  median  line,  and  forms 
a  sort  of  cervical  lima  alba.  From  this  linea  alba  two  layers  proceed  in  the  supra-hyoid 
region,  and  four  in  the  infra-hyoid  region,  which  are  arranged  in  the  following  manner 

1.  The  superficial  layer,  or  the  superficial  cervical  fascia,  covers  the  whole  anterior  and 
lateral  regions  of  the  neck,  is  prolonged  downward  in  front  of  the  clavicle,  to  become 
continuous  with  the  proper  aponeurosis  of  the  pectoralis  major,  is  attached  above  to  the 
masseteric  and  parotid  fasciae,  and,  internally  to  the  masseter  muscle,  is  fixed  to  the 
base  of  the  lower  jaw. 

It  fills  up  the  interval  between  the  two  platysmata,  and  is  prolonged  behind  these  mus- 
cles to  form  the  anterior  layer  of  the  sheath  of  the  stemo-mastoid.  The  external  jugu- 
lar vein  is  superficial  to  this  layer  in  the  sub-hyoid,  and  lies  beneath  it  in  the  supra-hyoid 
region. 

2.  The  deep  layer  passes  beneath  the  stemo-mastoid,  on  the  outer  border  of  which  it 
unites  with  the  preceding  layer,  and  completes  the  sheath  for  that  muscle.  It  covers 
the  internal  jugular  vein,  the  common  carotid  artery,  the  pneumogastric  nerve,  the  great 
sympathetic,  and  its  cervical  ganglia.  Its  upper  margin  is  attached  to  the  base  of  the 
lower  jaw ;  its  lower  margin  to  the  posterior  surface  of  the  clavicle,  and  to  the  posterior 
edge  of  the  fourchette  of  the  sternum.  It  is  necessary  to  examine  this  deep  layer,  both 
in  the  supra  and  sub  hyoid  region. 

In  the  supra-hyoid  region  its  middle  portion  is  very  strong,  and  occupies  the  triangu- 
lar space  between  the  anterior  bellies  of  the  digastric  muscles  ;  it  is  fixed  by  its  lower 
margin  to  the  os  hyoides,  and  on  each  side  to  the  tendon  of  the  digastricus.  The  lat- 
eral portions  of  this  aponeurosis  pass  beneath  the  sub-maxillary  glands,  and  are  attached 
to  the  rami  of  the  lower  jaw.  Externally  to  these  glands  they  join  the  parotid  aponeu- 
roses, and  form  a  tolerably  thick  septum  between  the  sub-maxillary  and  parotid  glands  of 
either  side. 

In  the  sub-hyoid  region  this  deep  layer  is  divided  into  three  very  distinct  parts,  a  mid- 
dle and  two  lateral.  The  middle  is  the  stronger ;  it  occupies  the  triangular  space  be- 
tween the  two  omo-hyoid  muscles,  and  becomes  continuous  with  their  median  tendons  : 
the  muscles  may,  therefore,  be  regarded  as  the  tensors  of  this  facia.  It  binds  down  the 
muscles  of  the  infra-hyoid  region  :  its  arrangement  explains  why  abscesses  situated  in 
front  of  it  discharge  their  contents  through  the  skin,  and  not  into  the  thorax,  as  those  do 
that  are  subjacent  to  it.  The  lateral  parts  of  the  aponeurosis  constitute  the  supra-clavic- 
ular fascia,  a  very  strong  layer,  in  which  the  superficial  layer  already  described,  and  the 
two  which  yet  remain  to  be  noticed,  all  terminate.  It  occupies  the  whole  triangular 
space  between  the  trapezius  and  the  stemo-mastoid,  is  continuous  with  the  fibro-cellular 
sheath  of  the  former  muscle,  and  adheres  below  to  the  clavicle.  The  latter  circumstance 
is  of  great  importance  in  relation  to  surgical  anatomy. 

The  superficial  and  deep  layers  which  we  have  now  described  are  common  to  both 
the  supra  and  sub  hyoid  regions.  In  the  sub-hyoid  region  there  are  two  other  aponeurotic 
layers :  one,  very  thin,  separating  the  superficial  from  the  deep  muscles,  i.  c,  the  omo 
and  sterno  hyoidei  from  the  sterno-thyroidei  and  thyro-hyoidei ;  the  other,  thicker,  pass- 
ing between  the  sterno-thyroidei  and  the  trachea.  The  latter  is  the  fourth  layer,  which 
Godman  incorrectly  describes  as  continuous  with  the  pericardium. 

The  Prevertebral  Aponeurosis. 

This  aponeurosis  covers  the  muscles  of  the  prevertebral  region,  viz.,  the  longi  colli, 

and  the  great  and  small  anterior  recti :  it  is  prolonged  on  each  side  upon  the  scaleni,  the 

levator  anguli  scapula;,  and  the  brachial  plexus  ;  and  is  attached  to  the  upper  border  of 

the  scapula,  and  to  the  outer  half  of  the  posterior  border  of  the  clavicle.     It  completely 


^&b  APONEUROLOGY. 

separates  the  axilla  from  the  neck,  and  is  perforated  by  several  vessels.  It  prevents 
large  abscesses  of  the  neck  from  opening  into  the  axilla  ;  and,  in  caries  of  the  cervical 
vertebrae,  it  retains  the  pus  poured  out  against  it,  so  as  to  form  abscesses  by  accumulation. 

The  Thoracic  Aponeuroses. 
The  Intercostal  Aponeurosis. 
Independently  of  the  semi-tendinous  structure  of  the  intercostal  muscles,  we  find  sev- 
eral fibrous  layers  in  each  intercostal  space  :  one  layer  in  front,  continuous  with  the  ex- 
ternal intercostal  muscle  ;  another  behind,  continuous  with  the  internal  intercostal  mus- 
cles ;  and,  situated  within  these  muscles,  a  third  layer,  which  lines  them  and  separates 
them  from  the  pleura.  The  existence  of  this  sub-serous  aponeurosis  accounts  for  the 
rare  occurrence  of  the  bursting  of  an  external  abscess  of  the  chest  into  the  cavity  of  the 
pleura ;  and,  on  the  other  hand,  of  the  escape  of  collections  in  the  pleura  by  external 
openings. 

The  Aponeurosis  of  the  Serrati  Postici. 
In  the  dorsal  region  of  the  trunk,  we  find  a  very  thin  fibrous  layer  (sometiriies  called 
the  vertebral  aponeurosis),  extending  between  the  two  serrati  postici.  It  is  of  a  quadri- 
lateral form ;  its  inner  margin  is  attached  to  the  summits  of  the  dorsal  spinous  process- 
es ;  its  outer  margin  to  the  angles  of  the  ribs,  and  its  lower  margin  to  the  upper  border 
of  the  serratus  posticus  inferior ;  it  seldom  terminates  at  the  lower  border  of  the  serratus 
posticus  superior,  but  generally  passes  beneath  it,  and  becomes  the  investing  aponeuro- 
sis of  the  splenius.  The  use  of  this  aponeurosis  is  evidently  to  confine  the  posterior  spi- 
nal or  long  muscles  of  the  back. 

The  Abdomistal  Aponeuroses. 
The  parietes  of  the  abdomen  are  partly  muscular  and  partly  aponeurotic :  the  muscu- 
lar portions  are  situated  at  the  sides  of  the  abdomen.  The  aponeurotic  portions  occupy 
the  anterior  and  posterior  regions,  and  form  the  anterior  and  posterior  abdominal  aponeu- 
roses. The  extensibility,  elasticity,  and,  above  all,  the  contractility  of  the  abdominal  pa- 
rietes, depend  on  the  three  intersecting  muscular  layers  ;  while  to  the  aponeuroses  must 
be  attributed  their  capability  of  resistance  and  want  of  extensibility. 

The  Anterior  Abdominal  Aponeurosis. 

The  anterior  abdominal  aponeurosis  forms  the  greater  part  of  the  anterior  wall  of  the 
abdomen.  It  consists,  1.  Of  a  fibrous  column,  which  is  continuous  with  the  osseous  col- 
umn of  the  sternum  ;  and,  2.  Of  two  perfectly  corresponding  halves,  one  right,  the  other 
left.  These  two  halves  are  united  in  the  linea  alba,  which  may  be  regarded  as  their  com- 
mon origin. 

The  Linea  Alba. 

The  linea  alba  {i,figs.  109,  110)  is  a  tendinous  raphe,  extending  from  the  ensiform 
cartilage  to  the  symphysis  pubis  ;  it  constitutes  the  anterior  median  line  of  the  abdomen. 
In  a  theoretical  point  of  view  it  may  be  regarded  as  a  continuation  of  the  sternum,  which, 
in  some  animals,  is  prolonged  as  far  as  the  pubes.* 

Anatomists  are  not  agreed  as  to  the  acceptation  of  the  term  linea  alba.  According 
to  some,  it  is  a  mathematical  line  produced  by  the  intersection  of  the  aponeuroses  of 
one  side  with  those  of  the  other :  according  to  others — and  this  njeaning  appears  to  me 
preferable — it  consists  of  the  tendinous  band  comprised  between  the  inner  borders  of  the 
recti. 

Thus  defined,  the  breadth  of  the  linea  alba  corresponds  to  the  interval  between  these 
muscles,  and,  as  they  are  directed  somewhat  obliquely  upward  and  outward,  it  follows 
that  the  upper  or  supra-umbilical  portion  of  the  linea  alba  is  broader  than  that  portion 
which  is  below  the  umbilicus.  This  remarkable  arrangement,  by  which  the  strength  of 
the  lower  part  of  the  abdomen  is  secured,  affords  an  explanation  of  the  uniform  occur- 
rence of  hernias  through  the  linea  alba  above,  not  below,  the  umbilicus.  It  should  also 
be  observed  that,  during  exertion,  the  viscera  are  chiefly  forced  against  the  lower  part  of 
the  abdominal  parietes,  and  also  that  the  gravid  uterus  rests  upon  it. 

The  sub-umbihcal  portion  of  the  linea  alba  forms  a  mere  line,  while  the  supra-umbili- 
cal is  about  a  quarter  of  an  inch  in  breadth.  Its  transverse  dimensions  are  much  in- 
creased in  persons  whose  abdomen  has  been  greatly  distended.  Thus,  during  and  after 
pregnancy  and  certain  dropsies,  it  in  some  cases  acquires  a  considerable  breadth,  and 
does  not  return  to  its  original  size,  even  after  the  distension  has  ceased  to  exist.  In  a 
female  who  died  a  short  time  after  delivery,  I  found  the  linea  alba  three  inches  across 
at  the  umbilicus,  and  fifteen  lines  in  the  narrowest  part.  In  cases  of  this  kind,  the  linea 
alba  forms  a  sort  of  long  pouch,  which  receives  the  intestines,  and  becomes  very  prom- 
inent  during  the  contraction  of  the  recti. 

The  linea  alba  presents  several  elliptical  openings  for  the  passage  of  nerves  and  ves- 

*  The  anal.ip.v  has  pveu  bpen  cnrried  so  far,  that  the  tendinous  intersections  of  the  recti  have  been  C«a» 
JtarecJ  to  the  ri'.is,  Tt  tht>y  seeiii  to  ciime  off  from  the  linea  alba  like  abdominal  ribs. 


THE    ANTERIOR    ABDOMINAL    APONEUROSIS.  301 

sels.  In  these  foramina,  round  masses  of  fat  are  developed,  which  dilate  them,  and  draw 
down  the  peritoneum  into  them,  or  are  absorbed  in  consequence  of  emaciation,  and  thus 
open  an  easy  way  for  the  production  of  hernia  of  the  linea  alba.  Of  all  these  orifices, 
the  most  remarkable  is  the  umbikcal  ring,  which  gives  passage  to  the  umbilical  vessels  in 
the  foetus,  but  becomes  cicatrized  after  birth,  at  least  in  the  majority  of  subjects.* 

The  situation  of  the  umbilicus  varies  at  different  ages.  The  middle  point  of  the  length 
of  the  body  is  situated  above  the  umbilicus  before  the  sixth  month  of  foetal  existence, 
and  corresponds  with  it  after  that  period.  In  the  adult  it  is  situated  below  the  umbil- 
icus. Its  situation  with  regard  to  the  abdomen  varies  in  different  individuals.  Thus, 
the  umbilical  cicatrix,  which  is  generally  a  little  below  the  middle  of  the  abdomen,  is 
sometimes  exactly  in  the  middle.  I  have  even  seen  it  at  the/ point  of  junction  of  the 
lower  with  the  upper  two  thirds. 

This  cicatrix,  moreover,  is  much  stronger  than  the  neighbouring  parts.  Thus,  an 
umbilical  hernia,  which,  in  a  new-born  infant,  always  occupies  the  navel  itself,  in  an 
adult  is  almost  invariably  situated  a  little  above  the  umbilicus.  Still  it  occasionally 
yields,  either  in  cases  of  dropsy  or  of  hernia  ;  and  I  have  records  of  several  instances  of 
hernia  in  the  adult,  that  have  occurred  through  the  umbilical  ring. 

The  linea  alba  is  in  relation,  in  front,  with  the  skin,  which  adheres  more  closely  to  it 
than  to  the  neighbouring  parts,  especially  opposite  the  umbilicus.  In  the, male,  it  is  sep- 
arated from  the  skin  below  by  th,e  suspensory  ligament  of  the  penis,  which  sometimes 
extends  as  far  as  the  middle  of  the  space  between  the  pubes  and  the  umbilicus  :  behind, 
it  is  in  relation  with  the  peritoneum,  separated  from  it,  however,  by  the  remains  of  the 
urachus,  and  by  the  bladder  itself,  when  that  viscus  is  distended.  It  is,  then,  through 
the  linea  alba  that  the  bladder  is  punctured  in  cases  of  retention  of  urine,  and  that  the 
incision  is  made  in  the  high  operation  of  lithotomy.  The  peritoneum  does  not  adhere 
more  closely  to  the  umbilicus  than  to  the  other  parts  of  the  abdomen,  and  therefore  um- 
bilical hemiae,  like  all  others,  are  invariably  provided  with  a  proper  sac. 

The  upper  extremity  of  the  linea  alba  is  attached  to  the  ensiform  appendix,  a  flexible, 
elastic,  cartilaginous  body,  constituting,  as  it  were,  a  transitional  structure  between  the 
sternum  and  the  part  we  are  now  describing. 

The  lower  extremity  corresponds  to  the  symphysis  pubis. 

If  we  examine  the  structure  of  the  linea  alba,  we  shall  see  that  it  is  formed  by  the  in- 
tersection of  the  layers  of  the  anterior  abdominal  aponeuroses.  One  remarkable  circum- 
stance is,  that  the  intersecting  fibres  do  not  stop  at  the  median  line,  but  pass  from  one 
side  to  the  other ;  so  that  the  tendinous  fibres  of  the  external  oblique  of  the  right  side 
become  the  tendinous  fibres  of  the  internal  oblique  of  the  left  ;  and,  again,  that  the  inter- 
section occurs  not  only  from  side  to  side,  but  also  from  before  backward.  Below  the 
umbilicus  the  point  of  intersection  is  elevated  by  some  longitudinal  fibres,  constituting 
a  small  and  very  distinct  cord,  which  appears  to  form  a  septum  between  the  recti  mus- 
cles ;  it  increases  in  thickness  as  it  proceeds  downward  from  the  umbilicus  to  the  sym- 
physis, and  may  be  easily  felt  under  the  skin  in  emaciated  individuals.  We  may  add, 
that  the  fibres  of  the  linea  alba  have  no  resemblance  to  the  yellow  elastic  tissue  ;  they 
are  neither  extensible  nor  elastic,  at  least  in  the  human  subject.  Its  uses  entirely  re- 
fer to  its  capability  of  offering  resistance. 

The  pyramidales  are  its  tensor  muscles. 

The  Four  Layers  of  the  Anterior  Abdominal  Aponeurosis. 

From  each  side  of  the  linea  alba  {a,  Jig.  134,  a  diagram  representing  a  horizontal  sec- 
tion of  the  abdominal  parietes)  two  fibrous  layers  proceed  Fig.  134. 
out'vard,  one  anteriorly,  the  other  posteriorly,  to  the  rec- 
tus muscle  (r). 

The  anterior  layer  (b),  having  arrived  near  the  outer  bor- 
der of  the  muscle,  subdivides  into  two  other  layers :  one 
superficial,  constituting  the  aponeurosis  of  the  external  ob- 
lique (d) ;  the  other  deep,  forming  the  anterior  layer  of  the 
aponeurosis  of  the  internal  oblique  (e).  The  posterior  lay- 
er (c)  is  also  simple  as  far  as  the  outer  border  of  the  rec- 
tus, and  then  separates  likewise  into  two  layers  :  one  an- 
terior, which  becomes  united  with  the  aponeurosis  of  the 
internal  oblique  (e),  and  is  regarded  as  the  posterior  layer 
of  that  aponeurosis ;  the  other  posterior,  which  continues 
its  course  outward  from  the  rectus,  and  forms  the  aponeu- 
rosis of  the  transversaUs  muscle  (/).  We  shall  describe 
these  different  parts  in  succession. 

The  Aponeurosis  of  the  External  Oblique. — This  is  the  most  superficial  layer,  and  is 
)f  a  quadrilateral  figure  {a,  fig.  109) ;  it  is  broad  below,  where  it  corresponds  to  the  in- 

*  Some  cases  are  on  record  of  the  persistence  of  the  umbilical  vein,  and,  consequently,  of  the  umbilical  ring. 
I  have  nariated  a  case  where  a  sub-cutaneous  abdominal  vein,  prodigiously  developed,  became  continuous  with 
the  vena  cava,  which  was  also  very  large. — {Anat.  Path.,  1.  xvi.,  pi.  6.) 


APONEUROLOGY. 


terval  between  the  anterior  superior  spinous  process  of  the  ilium  and  the  linea  alba,  be- 
comes narrower  immediately  above,  and  again  expands  at  the  upper  part,  but  to  a  less 
extent  than  below. 

It  is  covered  by  the  skin  and  the  superficial  fascia,  and  it  covers  the  aponeurosis  and 
the  anterior  portion  of  the  fleshy  fibres  of  the  internal  oblique.  It  adheres  intimately  to 
the  aponeurosis  of  the  internal  oblique,  as  far  as  the  vicinity  of  the  outer  border  of  the 
rectus,  excepting  below,  where  the  two  fasciae  are  perfectly  distinct,  and  can  be  easily 
separated  throughout  their  entire  extent. 

Its  external  margin,  slightly  concave  and  denticulated,  presents  irregular  prolongations, 
with  which  the  fleshy  fibres  become  continuous.  A  line  extending  from  the  anterior 
superior  spinous  process  of  the  ilium  to  the  extremity  of  the  cartilage  of  the  eighth  rib, 
will  indicate  with  tolerable  accuracy  the  direction  of  this  margin,  which  appears  to  be 
divided  into  two  layers,  one  superficial,  very  thin,  and  continuous  with  the  proper  cel- 
lulo-fibrous  sheath  of  the  muscle ;  the  other  deep,  and  giving  origin  to  fleshy  fibres. 

Its  upper  margin  is  narrow,  and  cannot  be  exactly  defined ;  it  often  gives  attachment 
to  some  fibres  of  the  pectoralis  major. 

Its  lower  margin  consists  of  two  very  distinct  portions :  one,  extending  from  the  ante- 
rior superior  spinous  process  of  the  ilium  to  the  spine  of  the  os  pubis,  is  called  the  fem- 
oral arch  (p  p',figs.  136,  137) ;  the  other,  stretching  between  the  spine  and  the  symphy- 
sis pubis,  offers  for  consideration  the  pillars  and  the  cutaneous  orifice  of  the  inguinal 
canal  (m,  figs.  109,  136,  137). 

The  aponeurosis  of  the  external  oblique  is  composed  of  tendinous  fasciculi,  directed 
obliquely  downward  and  inward,  like  the  fleshy  fibres  with  which  they  are  continuous. 
It  is  also  perforated,  especially  in  the  neighbourhood  of  the  linea  alba,  by  a  considerable 
number  of  bloodvessels  and  nerves.  Not  unfrequently  the  component  fasciculi  have 
between  them,  especially  near  the  femoral  arch,  linear  or  triangular  spaces  of  variable 
size,  through  which  the  fibres  of  the  internal  oblique  are  visible.  The  component  fas- 
ciculi are  also  intersected  at  right  angles,  and,  as  it  were,  bound  down  by  other  tendi- 
nous fibres,  which  are  more  or  less  developed  in  different  individuals,  and  are  most  usu- 
ally situated  in  the  neighbourhood  of  the  femoral  arch. 

Having  made  these  preliminary  observations,  we  shall  now  describe  in  detail,  1.  The 
lower  margin  of  the  aponeurosis  of  the  external  oblique,  or  the  femoral  arch;  and,  2.  The 
inguinal  ring  and  canal. 

Th&  Femoral  or  Crural  Arch. — ^When  the  aponeurosis  of  the  external  oblique  has  ar- 
Fig.  136.  rived  opposite  a  line  extending  from 

the  anterior  superior  spinous  pro- 
cess of  the  ilium  to  the  spine  of  the 
pubes,  it  suddenly  terminates,  be- 
comes thickened,  and  is  reflected 
(a  a',  fig.  137)  from  before  back- 
ward upon  itself  The  reflected 
border  {pp',figs.  136, 137)  has  been 
variously  denominated  the  femoral 
or  crural  arch,  the  reflected  margin 
of  the  teiidon  of  the  external  oblique, 
PouparVs  ligament,  and  the  ligament 
of  Fallopius. ,  This  arch,  which  is 
stretched  like  a  cord,  corresponds 
to  the  fold  of  the  groin,  and  defines 
the  limits  of  the  abdomen  and  the 
lower  extremity :  it  forms  the  ar 
terior  border  of  a  considerable  tri- 
angular space,  which  is  completed 
by  the  ilium  (I,  fig.  136)  on  the  out- 
side, and  by  the  os  pubis  (2)  behind. 
This  space  establishes  a  communi- 
cation between  the  lower  extremi- 
ty and  the  abdomen,  and  is  occupied  (proceeding  from  without  inward)  by  the  psoas  and 
aiacus  muscle  (»  to  i),  the  crural  nerve  (n),  the  femoral  artery  (a)  and  vein  {v),  and  the 
pectineus  muscle.* 

The  crural  arch  is  directed  somewhat  obliquely  downward  and  inward ;  and  as  its  out- 
er third  is  more  oblique  than  the  inner  two  thirds,  it  describes  externally  a  slight  curve, 
having  its  concavity  directed  upward.  Its  lower  or  reflected  border  is  continuous  with 
the  fascia  of  the  thigh.  This  adhesion  occasions  the  tension  of  the  arch,  as  may  be 
shown  by  cutting  the  femoral  fascia  at  the  point  of  its  junction  with  the  arch :  hence 
the  precept  of  Scarpa,  who  recommended  incisions  to  be  made  in  this  situation,  in  order 
to  relieve  the  constriction  in  femoral  hernise. 
The  free  margin  of  the  reflected  portion  of  the  aponeurosis,  of  which  the  femoral  arch 

*  This  is  not  represented  in  the  woodcut. 


^^ 


THE   CRURAL    ARCH.  303 

consists,  is  continued  backward  into  the  iliac  fascia  («')  externally ;  and  internally,  into 
the  fascia  transversalis  (t). 

Externally  near  the  psoas  and  iliacus  (beyond  a',  fig.  137),  the  posterior  or  reflected 
portion  of  the  arch  is  closely  blended  with  its  anterior  or  direct  portion,  as  well  as  with 
the  iliac  fascia  and  the  fascia  of  the  thigh,  so  that,  in  this  situation,  there  is  a  thickening 
rather  than  an  actual  reflection  of  the  aponeurosis.  Internally  to  the  psoas  and  iliacus, 
however  (at  a),  the  direct  and  reflected  portions  are  perfectly  distinct,  and  form  a  groove 
with  its  concavity  upward,  which  we  shall  find  to  assist  in  the  formation  of  the  inguinal 
canal.  These  two  separate  portions  of  the  inner  part  of  the  femoral  arch  require  a  spe- 
cial description. 

The  direct  portion  (part  of  which  is  shown  turned  downward  at  d,  fig.  137)  passes  on 
to  be  attached  to  the  spine  of  the  pubes  (p,figs.  136,  137),  becoming  more  and  more 
prominent,  so  that  it  can  be  easily  felt  under  the  skin,  especially  when  the  thigh  is  ex- 
tended upon  the  pelvis.  The  reflected  portion,  externally,  is  narrow,  and,  as  it  were, 
folded ;  but  internally  it  becomes  expanded,  from  its  fibres  slightly  changing  their  direc- 
tion, and  diverging,  so  as  to  be  inserted  into  the  spine  of  the  pubes  behind  the  direct 
portion,  and  also  into  the  pecten  or  crest  of  the  pubes. 

This  reflected  and  expanded  portion,  described  even  in  the  oldest  anatomical  works, 
has  become  celebrated  in  recent  times  under  the  improper  name  of  Gimbernat's  ligament 
{g,fig.  136),  from  a  Spanish  surgeon,  who  pointed  out  its  importance  as  the  seat  of  stric- 
ture in  femoral  hernia.  It  is  triangular  in  shape  ;  its  anterior  margin  corresponds  to  the 
crural  arch ;  its  posterior  margin  to  the  crest  of  the  pubes ;  its  outer  margin  is  free,  con- 
cave, tense,  and  sharp,  and  forms  the  inner  part  of  the  circumference  of  the  crural  ring 
(r).  This  concavity,  against  which  the  protruded  intestine  becomes  strangulated,  has 
obtained  for  the  ligament  the  name  of  the  falciform  ligament  or  fold.*  Its  strength  is 
very  considerable  ;  but,  occasionally,  intervfds  are  left  between  its  fibres,  through  which 
hernial  protrusions  may  take  placet 

From  the  lower  surface  of  Gimbernat's  ligament  a  fibrous  prolongation  is  given  off, 
which  sometimes  represents  a  second  arch  below  the  femoral  arch,  and  assists  in  form- 
ing the  superficial  layer  of  the  fascia  lata  of  the  thigh.  This  tendinous  expansion  has  a 
great  effect  in  rendering  the  arch  tense.  We  may  add,  that  there  is  considerable  vari- 
ation in  different  subjects,  both  in  the  strength  and  development  of  Gimbernat's  liga- 
ment ;  varieties  that  must  have  great  influence  on  the  position  of  crural  herniae,  and  on 
the  seat  of  strangulation  in  that  disease.  Behind  the  femoral  arch,  on  the  outer  side  of 
Gimbernat's  Ugament,  is  an  opening  (a  to  r,fig.  136)  or  rkig,  intended  to  give  passage  to 
the  femoral  artery  (a)  and  vein  (v),  and  to  a  great  number  of  lymphatic  vessels  and  glands : 
this  is  the  crurcU  ring.X  The  sub-peritoneal  cellular  tissue  sometimes  acquires  great 
strength  opposite  this  ring,  and  constitutes  what  is  called  the  crural  septum  (situated  at  r). 
The  form  of  the  crural  ring  is  that  of  an  isosceles  triangle,  the  base  of  which  is  very 
long,  and  formed  by  the  cniral  arch,  the  inner  border  by  the  pectineus,  and  the  outer  by 
the  psoas  and  iliacus  muscles.  Of  the  three  angles,  the  internal  is  rounded,  and  corre- 
sponds to  the  concave  margin  of  Gimbernat's  ligament ;  the  external  angle,  opposite 
which  the  epigastric  artery  is  situated,  is  very  acute,  and  corresponds  to  the  point  at 
which  the  femoral  arch  separates  from  the  iliac  fascia ;  the  posterior  angle  is  very  ob- 
tuse, and  corresponds  to  the  ilio-pectineal  eminence  {d). 

The  femoral  vein  is  in  relation  with  the  inner  or  pectineal  border  of  this  triangular 
space  ;  the  femoral  artery  with  the  ilio-pectineal  eminence  and  the  outer  border.  The 
crural  nerve  («)  lies  behind  and  externally  to  the  artery,  being  separated  from  it  only  by 
the  iliac  fascia  («')•   Crural  herniae  descend  through  the  inner  portion  of  the  crural  ring.^ 

The  femoral  arch  is  formed  by  proper  fibres,  arising  from  the  anterior  superior  spinous 
process  of  the  ilium  ;  and  also  by  those  fibres  of  the  aponeurosis  of  the  external  oblique, 
which,  after  having  arrived  at  the  arch,  change  their  direction,  become  reflected  inward, 
and  are  collected  together,  so  as  to  form  a  strong  and  tense  cord. 

The  Inguinal  Ring  and  Canal. — On  the  inner  side  of  the  spine  of  the  os  pubis,  between 
the  spine  and  the  symphysis,  the  aponeurosis  of  the  external  oblique  divides  into  two 
almost  parallel,  or  at  least  very  slightly  diverging,  bands,  which  leave  between  them  an 
opening  for  the  passage  of  the  spermatic  cord  in  the  male,  and  of  the  round  ligament  in 
the  female.  This  opening  is  the  inguinal  ring  {m,figs.  109,  136,  137),  and  the  bands 
which  form  its  limits  are  called  the  pillars  (o  p,  figs.  136,  137).  The  inguinal  ring  is  oval 
or  triangular  ;  its  greatest  diameter  has  the  same  direction  as  the  fibres  of  the  external 
obUque,  viz.,  obliquely  downward  and  inward.     Its  base  corresponds  to  the  interval  be- 

*  tTnis  term  is  now  generally  applied  (after  Bums)  to  the  external  margin  of  the  saphenous  opening  {n,Jig. 
137)  in  the  fascia  lata.] 

t  M.  Laugier  has  lately  recorded  a  case  of  hernia  through  the  fibres  of  Gimbernat's  ligament.  I  have  since 
had  an  opportunity  of  seeing,  in  an  old  woman  at  the  Salptr^iere,  two  hernial  sacs  near  each  other,  one  of 
which  protruded  through  the  crural  ring,  and  the  other  internally  to  the  ring;  the  necks  of  these  sacs  wer« 
separated  by  a  fibrous  band,  which  appeared  to  me  to  be  formed  by  the  external  fibres  of  Gimbernat's  ligament. 

X  [The  term  "  crural  ring,"  it  must  be  remembered,  is  limited  by  British  anatomists  and  surgeons  to  the 
small  space  (r),  bounded  internally  by  the  free  margin  of  Gimbernat's  ligament,  and  externally  by  the  femora] 
vein.  It  is  through  this  space,  and  therefore  through  the  internal  portion  only  of  the  "  crural  ring"  of  M 
CrUTcilhier,  that  crural  hemiEB  descend.]  I)  See  note,  supa. 


304 


APONEUftOLOGY. 


Fig.  IS".  tween  the  spine  and 

symphysis  pubis.  Its 
apex  is  not  always 
well  defined,  and  is 
generally  truncated 
by  fibres  which  pass 
at  right  angles  to  its 
pillars.  From  the  up- 
per part  of  the  margin 
of  the  ring  a  tendi- 
nous prolongation  is 
given  off,  which  ac- 
companies the  sper- 
matic cord  in  the 
male,  and  the  round 
ligament  in  the  fe- 
male. 

Of  the  pillars,  one 
is  external  or  inferior, 
the  other  internal  or 
superior.  The  external 
pillar  (p)  is  attached, 
not  to  the  spine  of  the 

OS  pubis,  but  into  the  fore  part  of  the  symphysis :  this  pillar  is  nothing  more  than  the  in- 
ternal extremity  of  the  direct  portion  of  the  femoral  arch.  Moreover,  some  anatomists 
consider  Gimbemat's  ligament  as  the  reflected  portion  of  the  external  pillar.  The  internal 
pillar  (o)  is  broader  than  the  external,  and  intersects  the  corresponding  structure  of  the 
opposite  side  in  front  of  the  symphysis,  not  unfrequently  some  fibres  of  the  right  internal 
pillar  intersecting  those  of  the  left  external  pillar. 

Inguinal  Canal  or  Passage. — The  inguinal  ring^  {m)  is  the  anterior  or  cutaneous  orifice 
of  an  oblique  passage,  formed  in  the  substance  of  the  lower  edge  of  the  inferior  parietes 
of  the  abdomen  opposite  the  crural  arch,  and  destined  to  transmit  the  cord  (s)  of  the 
spermatic  vessels  in  the  male,  and  the  round  ligament  of  the  uterus  in  the  female.  This 
passage,  which  modern  writers  only  have  correctly  described,  has  been  styled  by  them 
the  inguinal  canal  (i  c  wi).  Its  length  varies  from  an  inch  and  a  half  to  two  inches  and  a 
half;  it  is  directed  obliquely  downward,  forward,  and  inward. 

The  inguinal  canal  is  formed,  in  reality,  by  the  groove  resulting  from  the  reflection 
backward  of  the  aponeurosis  of  the  external  oblique  (at  a),  the  posterior  border  of  which 
groove  is  continuous  with  the  fascia  transversalis,  and  its  anterior  border  with  the  apo- 
neurosis of  the  external  oblique  itself  We  may,  then,  consider  this  passage  as  having 
an  inferior  concave  wall  (at  a)  formed  by  the  groove  of  reflection  ;  an  anterior  wall,  formed 
by  the  aponeurosis  of  the  external  oblique  (shown  turned  downward  at  d) ;  and  a  posterior 
wall,  formed  by  the  fascia  transversalis  (c).  There  is  no  superior  wall,  or,  rather,  it  is  sup- 
plied by  the  lower  margins  of  the  internal  oblique  (c)  and  transversalis  (/)  muscles, 
which  occupy  the  groove  of  the  crural  arch,  and  receive  from  it  externally  numerous 
points  of  attachment.  Internally  the  margins  of  these  muscles  are  separated  from  the 
groove  by  the  spermatic  cord,  or  the  round  ligament.  It  has  been  supposed  that  this 
canal  is  lined  by  a  funnel-shaped  prolongation  of  the  fascia  transversalis.  The  peritoneal 
or  interrml  orifice  (t,  figs.  110,  137)  of  the  inguinal  canal  is  much  less  accurately  defined 
than  the  external,  or,  rather,  its  inner  border  alone  is  well  defined,  consisting  of  a  concave 
fibrous  edge  fonned  by  the  fascia  transversalis,  and  somewhat  analogous  to  the  concave 
edge  of  Gimbemat's  ligament.  The  strangulation  of  the  intestine  in  inguinal  hernia 
sometimes  occurs  against  this  edge.  The  peritoneal  orifice  of  the  inguinal  canal  is  closed 
by  the  peritoneum,  and  the  epigastric  artery  runs  aloug  its  inner  border. 

The  testicle,  which  is  originally  situated  within  the  abdomen,  descends  through  the 
inguinal  canal ;  so,  also,  do  those  herniae,  commonly  called  oblique  inguinal  hemis,  in 
order  to  distinguish  them  from  the  direct  or  internal  inguinal  herniae. 

The  Anterior  Aponeurosis  of  the  Obliquus  Internus  and  Transversalis. — The  aponeurosis 
of  the  internal  oblique  commences  at  the  linea  alba,  and  immediately  divides  in  its  upper 
three  fourths  into  two  layers,  one  of  which  passes  in  front,  and  the  other  behind  the  rectus 
(r,  fig.  1 34).  The  lower  fourth  passes  entirely  in  front  of  the  same  muscle  without  division 
(as  shown  in^^.  135).  The  anterior  layer  is  very  closely  united  with  the  aponeurosis  of 
the  external  oblique  (at  b),  from  which  it  can  be  distinguished  only  by  the  direction  of 
its  fibres.  In  some  parts  there  is  even  a  true  interlacement  between  the  tendinous  fibres 
of  these  two  muscles  ;  the  lower  or  undivided  portion  of  the  aponeurosis  of  the  internal 
oblique  may,  on  the  contrary,  be  easily  separated  from  that  of  the  external  oblique.  The 
posterior  layer  of  the  aponeurosis  of  the  internal  oblique  is  no  less  intimately  blended  with 
that  of  the  transversalis  (at  c),  from  which,  also,  it  is  to  be  distinguished  by  the  direction 
of  its  fibres  only.    At  the  outer  border  of  the  rectus  muscle  the  anterior  layer  of  the  apo- 


THE    FASCIA   TRANSVERSALIS,    ETC.  305 

aeuroFis  of  the  internal  oblique  separates  from  that  of  the  external  oblique,  and  the  pos- 
terior .ayer  from  that  of  the  transversalis,  and  then  immediately  unite  together,  and  give 
origin  to  the  fleshy  fibres.  The  outer  margin,  therefore,  of  the  aponeurosis  of  the  internal 
oblique  exactly  corresponds  to  the  outer  border  of  the  rectus,  and  is  directed  vertically. 
The  aponeurosis  of  the  transversalis  (/,  Jigs.  134,  135)  is  the  deepest  layer  of  the  an- 
terior abdominal  aponeurosis  :  it  is  very  narrow  above,  increases  in  breadth  as  far  down 
as  opposite  the  crest  of  the  ilium,  and  then  progressively  diminishes  towards  its  lower 
portion.  It  commences  at  the  linea  alba,  and  is  divided  into  two  portions  :  one  inferior 
(below  s,Jig.  110),  consisting  only  of  the  lower  fourth  of  the  aponeuroses,  and  passing  in 
front  of  the  rectus  (as  in  Jig.  135) ;  the  other  superior  (above  s,  Jig.  110),  which  passes 
behind  the  rectus  (as  in^^.  134),  and  is  formed  by  the  upper  three  fourths  of  the  apo- 
neurosis. Its  external  margin  is  convex,  and  gives  origin  to  the  fleshy  fibres  of  the 
muscle.  Its  anterior  surface  is  closely  united  to  the  aponeurosis  of  the  internal  oblique, 
beyond  which  it  passes  on  the  outside  :  its  posterior  surface  is  loosely  connected  with 
the  peritoneum,  excepting  in  its  lower  fourth,  which,  as  already  stated,  passes  in  front 
of  the  rectus  muscle.  The  tendinous  fibres  of  the  transversalis,  which  have  the  same 
direction  as  its  fleshy  fibres,  are  occasionally  found  not  to  terminate  abruptly  behind  the 
lower  part  of  the  rectus ;  but  the  aponeurosis  merely  becomes  thinner,  and  its  fasciculi 
separated  from  each  other. 

The  Fascia  Transversalis  and  Sub-peritoneal  Aponeurosis, 

In  order  to  complete  the  description  of  t"he  anterior  abdominal  aponeurosis,  it  only  re 
mains  for  me  to  describe  the  fascia  transversalis,  which  I  regard  as  a  thickened  portion 
of  the  sub-peritoneal  fascia. 

The  fascia  transversalis  (seen  at  a'  and  c,Jig.  137)  was  first  pointed  out  by  Sir  Astley 
Cooper,  but  has  been  more  correctly  described  by  Lawrence  and  J.  Cloquet :  it  com- 
mences below  at  the  reflected  border  (a  a')  of  the  crural  arch,  so  that  it  may  be  regard- 
ed as  a  thin  prolongation  of  the  reflected  portion  of  the  tendon  of  the  external  oblique. 
It  also  frequently  arises  from  the  brim  of  the  pelvis,  as  well  as  from  the  crural  arch. 
From  these  points  it  passes  upward,  becoming  more  and  more  attenuated  as  it  approach 
es  the  umbilicus,  at  which  point  it  cannot  be  distinguished  from  the  sub-peritoneal  apo- 
neurosis. 

The  fascia  transversalis  is  situated  between  the  abdominal  muscles  and  the  peri- 
toneum. Its  internal  margin  is  continuous  with  the  outer  border  of  the  rectus  muscle  ; 
and  its  external  margin,  which  gradually  becomes  thinner,  is  blended  with  the  sub-peri- 
toneal aponeurosis.  The  only  part  deserving  a  special  description  is  that  portion  which 
lies  between  the  outer  border  of  the  rectus  muscle  and  the  abdominal  opening  of  the  in- 
guinal canal.  In  this  situation  it  assists  in  strengthening  the  parietes  of  the  abdomen, 
which  are  here  remarkably  weak ;  and  it  is  to  the  existence  of  this  fascia  that  we  may 
attribute  the  extreme  rarity  of  direct  inguinal  hemiae*,  which,  in  fact,  can  only  result 
from  a  congenital  weakness,  or  a  relaxation  of  this  fascia. 

A  very  interesting  portion  of  the  fascia  transversalis  is  an  infundibuliform  prolonga- 
tion, given  off  from  it  to  the  spermatic  cord.  It  is  impossible,  indeed,  to  conceive  the 
descent  of  the  testicle  to  occur  without  its  pushing  before  it  a  portion  of  the  fascia, 
which  then  constitutes  the  immediate  investment  of  the  cord  upon  which  the  cremaster 
muscle  {b,Jig.  137)  is  spread  out.  The  peritoneal  orifice  of  the  inguinal  canal  is,  there- 
fore, the  superior  opening  of  the  infundibuliform  process,  furnished  by  the  fascia  trans- 
versalis to  the  testicle  and  its  cord. 

The  Sub-peritoneal  Aponeurosis. 
The  peritoneum,  throughout  the  whole  extent  of  the  abdominal  parietes,  is  strength- 
ened on  its  outer  surface  by  a  very  thin  tendinous  layer,  the  existence  of  which  may 
serve  to  explain  why  abscesses,  formed  in  the  parietes  of  the  abdomen,  so  seldom  open 
into  the  cavity  of  the  peritoneimi ;  and,  on  the  other  hand,  why  collections  within  the 
peritoneal  cavity  so  seldom  open  externally. 

The  Posterior  Abdominal  Aponeurosis. 
The  posterior  abdominal  aponeurosis  is  much  smaller  and  of  less  importance  than  the 
anterior :  it  consists  of  three  layers,  one  anterior  (Ji,  in  diagram,/^.  134),  and  very  thin, 
which  commences  at  the  base  of  the  transverse  processes  of  the  lumbar  vertebrae,  and 
passes  in  front  of  the  quadratus  lumborum  {q) ;  another,  middle  («),  and  much  stronger, 
commencing  at  the  summits  of  the  same  transverse  processes,  and  passing  behind  the 
quadratus  lumborum ;  and  a  third,  posterior  (k),  which  arises  from  the  summits  of  the 
lumbar  spinous  processes,  and  passes  behind  the  sacro-lumbalis,  longissimus  dorsi,  and 
transverso-spinalis  muscles  («).  This  last-mentioned  layer  is  connected  both  with  the 
internal  oblique  (e)  and  with  the  transversalis  muscle  (/),  and  is  blended  with  the  apo- 
neuroses of  the  serratus  posticus  inferior,  and  of  the  latissimus  dorsi  (/).     The  two  an- 

*  [/.  e.,  herniiE  occurring  directty  downward  and  forward  throagh  the  inguinal  ring  {.rn,jig.  J 37),  and  not 
descending  along  the  inguinal  canal.l 

Qq 


306  APONEUROLOGY. 

terior  layers  are  connected  with  the  transversalis  only.  The  posterior  abdominal  apo- 
neurosis has,  therefore,  nearly  the  same  relation  to  the  quadratus  lumborum  and  the 
common  mass  of  the  sacro-lumbalis,  longissimus  dorsi,  and  transverso-spinalis  muscles, 
that  the  anterior  aponeurosis  has  to  the  rectus  muscle. 

The  Lumho-iliac  Aponeurosis. 

The  lumbo-iliac  aponeurosis,  or  fascia  iliaca  of  modem  authors,  forms  the  tendinous 
sheaths  of  the  abdominal  portion  of  the  psoas  and  ihacus  muscles,  and  is,  therefore,  bi- 
furcated at  its  upper  part.  That  portion  which  invests  the  psoas  commences  at  the  ten 
dinous  arch  of  the  diaphragm,  already  described  as  embracing  the  upper  end  of  this  mus- 
cle. The  iliac  portion  arises  from  the  whole  extent  of  the  inner  border  of  the  crest  of  the 
ilium.  The  circumflex  ilii  artery  is  situated  in  the  substance  of  this  iliac  portion,  at  its 
origin.  The  internal  margin  of  the  fascia  iliaca  is  attached  to  the  sides  of  the  lumbar 
vertebrae,  and,  lower  down,  to  the  brim  of  the  pelvis ;  it  is  arranged  in  arches,  which 
give  passage  to  the  lumbar  vessels  and  to  the  nervous  cords,  establishing  a  communica- 
tion between  the  lumbar  plexus  and  the  lumbar  ganglia  of  the  sympathetic  nerve.  The 
centre  of  each  arch  is  opposite  to  the  groove  on  one  of  the  bodies  of  the  lumbar  verte- 
brae, the  intervals  between  the  arches  corresponding  with  the  intervertebral  substance. 
The  largest  arch  extends  from  the  last  lumbar  vertebra  to  the  brim  of  the  pelvis,  and  is 
opposite  to  the  base  of  the  sacrum.    The  obturator  and  lumbo-sacral  nerves  pass  under  it. 

Opposite  the  femoral  arch,  the  fascia  iliaca  adheres  intimately  to  the  outer  part  of 
Poupart's  ligament ;  but  towards  the  median  line  it  separates  from  that  ligament,  passes 
behind  the  femoral  vessels,  and  forms  the  posterior  half  {s,Jig.  136)  of  the  crural  ring. 

Below  the  femoral  arch,  the  fascia  is  prolonged  upon  the  thigh  ;  on  the  outside  («')  it 
completes  the  sheath  of  the  psoas  and  iliacus,  accompanies  them  as  far  as  the  lessei 
trochanter,  and  becomes  continuous  with  the  iliac  portion  {g,  fig.  137)  of  the  femoral 
fascia  ;  on  the  inside,  it  forms  the  posterior  wall  (s,  fig.  136)  of  the  canal  for  the  femoral 
vessels,  and  forms  the  deep  layer  or  pubic  portion  {h,fig.  137)  of  the  femoral  fascia. 

Relations. — It  lies  beneath  the  peritoneum,  to  which  it  is  united  by  a  very  loose  cellu- 
lar tissue  ;  it  covers  the  psoas  and  iliacus,  but  is  not  adherent  to  them,  in  consequence 
of  the  interposition  of  some  equally  delicate  cellular  tissue.  All  the  nerves  from  the 
lumbar  plexus  are  subjacent  to  this  fascia,  excepting  one  very  small  cord,  which  perfo- 
rates it  at  the  side  of  the  sacrum,  and  becomes  situated  in  the  sub-peritoneal  cellulai 
tissue.  The  femoral  vessels  are  situated  on  the  inner  side  of  the  fascia,  and  are  separ- 
ated by  it  from  the  crural  nerve,  which  lies  on  its  outer  side,  and  underneath  it. 

Structure. — The  upper  part  of  the  fascia  is  extremely  thin,  but  it  increases  in  thick- 
ness as  it  approaches  the  femoral  arch.  It  is  formed  of  well-marked  transverse  fasci- 
culi, intersected  perpendicularly  by  the  tendon  of  the  psoas  parvus,  when  that  muscle 
exists.  This  tendon  is  blended  with  the  fascia,  and  is  distinguished  from  it  only  by  the 
different  direction  of  its  fibres  ;  it  is  inserted  by  spreading  out,  at  the  side  of  the  pelvic 
brim,  into  a  tendinous  arch  which  lines  this  brim,  and  with  which  the  psoas  parvus  and 
the  iliac  fascia  are  continuous  above,  and  the  pelvic  fascia  below. 

Few  aponeuroses  are  more  deserving  the  attention  of  anatomists  than  this,  on  account 
of  the  practical  consequences  resulting  from  its  arrangement.  In  fact,  notwithstanding 
its  tenuity,  it  forms  a  boundary  between  the  sub-peritoneal  and  sub-aponeurotic  cellular 
tissue,  which  is  very  rarely  passed  by  inflammatory  action.  When  inflammation  termi- 
nates in  suppuration,  the  pus,  whether  it  be  beneath  the  peritoneum  or  beneath  this  fas- 
cia, descends  towards  the  femoral  arch  ;  but  if  the  inflammation  be  sub-peritoneal,  the 
femoral  vessels  lie  behind  the  purulent  collection  ;  and  should  it  be  sub-aponeurotic,  the 
vessels  will  be  in  front  of  it.  The  latter  is  especially  the  case  in  abscesses  following 
caries  of  the  vertebrae. 

The  Aponeuroses  of  the  Pelvis. 

The  aponeuroses  of  the  pelvis  should  be  distinguished  into  the  pelvic,  properly  so  called, 
and  the  perineal :  the  former  constitute  essential  parts  of  the  pelvis,  and  are  deeply  seat- 
ed. The  others  belong  to  that  part  of  the  floor  of  the  pelvis  which  is  called  the  perineum. 
I  shall  commence  with  the  description  of  the  latter. 

The  Aponeuroses  of  the  Perineum. 

These  are  two  in  number ;  one  superficial,  the  other  deep. 
The  Superficial  Perineal  Fascia.* 

Dissection. — Remove  tne  sub-cutaneous  adipose  tissue  very  cautiously,  layer  by  layer, 
commencing  the  dissection  along  the  edges  of  the  pubic  arch. 

This  aponeurosis  (which  is  very  distinct  from  the  fibrous  laminae,  intercepting  spaces 
filled  by  fat,  and  forming  what  is  called  the  fascia  superficialis)  is  of  a  triangular  shape, 
and  consists  of  well-marked  transverse  fibres.  The  outer  margin  of  each  half  of  the  fas- 
cia is  attached  to  the  descending  ramus  of  the  os  pubis  and  the  ascending  ramus  of  the 
ischium  :  its  inner  margin  is  lost  at  the  raphe,  along  the  median  line  :  its  posterior  maX' 

*  M  Bouvier,  in  his  thesis,  and  M.  Blandin,  in  his  Traiie  d'Anaiomie  Chirurgicale,  first  described  this  fascia 


THE    DEEP    PERINEAL    APONEUROSIS. 


807 


Fig.  138. 


^a  IS  bounded  by  a  line  extending  from  the  tuberosity  of  the  ischium  to  the  anus  ;  it  cor- 
responds with  the  posterior  edge  of  the  transversus  perinei  muscle,  and  appears  to  be 
reflected  behind  it,  so  as  to  line  the  corresponding  perineal  or  ischio-rectal  fossa.* 

Relations. — It  is  covered  by  a  prolongation  of  the  dartos,  to  a  greater  extent  in  the  me- 
dian line  than  on  each  side  ;  also  by  the  sub-cutaneous  adipose  tissue,  which  is  thicker 
behind  than  in  front,  and  by  the  sphincter  ani,  above  which  it  terminates  in  the  median 
line  :  it  covers  the  transversus,  the  bulbo-cavernosus,  and  the  ischio-cavernosus  mus- 
cles, the  fibrous  sheaths  of  which  may  even  be  regarded  a^  a  prolongation  of  this  aponeu- 
rosis. It  also  covers  the  superficial  perineal  vessels  and  nerves,  which  are  sometimes 
lodged  within  its  substance.  The  existence  of  this  membrane  explains  why,  in  cases 
of  perforation  of  the  urethra,  the  urine  is  infiltrated  forward,  and  very  rarely  backward. 
The  Deep  Perineal  Aponeurosis. 

Dissection. — Remove  with  great  care  the  ischio-  and  bulbo-cavernosus  and  the  trans- 
versus perinei  muscles. 

This  aponeurosis,  which  was  well  described  by  M.  Carcassone  under  the  name  ofpe. 
rineal  ligament,  and  called  by 
modern  writers  the  middle  pe- 
rineal fascia,  appears  to  me 
perfectly  distinct  from  the 
aponeuroses  of  the  pelvis.  It 
is  an  extremely  strong  trian- 
gular layer  {b  a,  fig.  138t),  oc- 
cupying the  pubic  arch,  and 
apparently  forming  a  continu- 
ation of  the  sub-pubic  ligament 
(jb).  It  is  vertical  near  the 
arch,  as  far  as  the  ball  of  the 
urethra,  below  which  it  be- 
comes horizontal,  or,  rather, 
oblique,  from  before  back- 
ward. Its  lateral  margins  are 
attached  to  the  descending  ra- 
mi of  the  ossa  pubis,  and  the 
ascending  rami  of  the  ischia 
{d,  d),  above  the  attachment  of 
the  ischio-cavernosi  muscles.  Its  posterior  margin  becomes  blended  with  the  posterior 
margin  of  the  superficial  perineal  fascia,  behind  the  transversi  muscles,  in  front  of  the 
perineal  fossse,  of  which  it  forms  the  anterior  boundary. 

Relations. — Its  lower  surface  is  in  relation  with  the  ischio-  and  bulbo-cavernosus  mus- 
cles, and  gives  off,  in  the  median  line,  a  fibrous  septum,  which  passes  between  these 
muscles,  and  affords  them  points  of  attachment.  Its  upper  surface  is  in  relation  with 
the  artery  or  arteries  (e  e)  of  the  bulb,  which  are  sometimes  contained  within  its  sub- 
stance :  it  is  also  in  contact  with  a  very  remarkable  plexus  of  large  veins,  with  which  it 
is  very  closely  united,  so  that,  when  divided,  they  remain  open  :  these  veins  are  also  fre- 
quently enclosed  within  its  substance.     It  is  also  in  relation  with  the  levator  ani. 

There  constantly  exists  another  transverse  muscle,  very  distinct  from  the  transversus 
perinei  generally  described,  which  is  situated  farther  behind.  This  muscle  (transversus 
perinei  alter.  Alb.)  is  applied  to  the  lower  surface  of  the  perineal  fascia,  and  passes  trans- 
versely inward  to  the  bulbous  portion  of  the  urethra. 

The  deep  fascia  of  the  perineum  is  perforated  (at  c)  by  the  posterior  part  of  the  bulb 
of  the  urethra,  or,  rather,  by  the  point  of  union  (c,  fig.  181)  between  its  bulbous  and 
membranous  portions  :  it  gives  off  prolongations  upon  the  sides  of  the  bulb,  and  serves 
to  support  the  membranous  portion  of  the  urethra :  whence  the  name,  triangular  liga- 
ment of  the  urethra,  given  to  it  by  CoUes.  It  is  also  perforated,  beneath  the  arch  of  the 
pubes,  by  a  great  number  of  veins,  and  by  some  arteries. 

Uses. — This  remarkable  aponeurosis  evidently  supports  the  canal  of  the  urethra.  It 
has  been  correctly  regarded  as  an  obstacle  to  the  introduction  of  the  catheter,  the  point 
of  which  strikes  against  it,  however  slightly  it  may  deviate  from  the  direction  of  the  ca- 
nal.   The  prostate  gland  is  situated  above  it. 

The  Pelvic  Jlponeuroses. 
From  the  sides  of  the  pelvis,  and  from  the  entire  circumference  of  the  brim  (which,  as 

*  Sec  note,  p.  309. 

t  [The  triangular  liganfient  consists  of  two  layers,  which  approach  each  other  more  ne.irly  above  tliati  below  . 
m^g-  138,  the  anterior  layer  has  been  removed.     Between  the  two  layers  are  situated  the  sub-pubic  ligamoa 
(A),  perforated  by  the  vena  dorsales  penis,  the  pudic  arteries  (//),  the  arteries  of  the  bulb  (e  e),  the  g^eat 
part  of  the  membranous  portion  of  the  urethra,  with  its  comjjressor  muscle,  to  be  described  hertaftiir,  an. 
lastly,  Cowper's  glands  (g  g).     In  the  female,  the  triingular  ligament  is  perforated  by  the  vagina,  as  wel 
bv  the  urethra.] 


308  APONEUROLOGY. 

we  have  seen,  is  covered  and  rendered  smooth  by  a  thick  layer  of  fibrous  tissue,  that 
forms  a  hmit  to  the  lumbo-iliac  aponeurosis),  a  tendinous  lamina  is  given  off,  which  pass- 
es into  and  lines  the  pelvis,  and  is  soon  divided  into  two  distinct  layers :  one  external, 
the  lateral  pelvic  or  obturator  fascia,  which  continues  to  line  the  sides  of  the  pelvis,  and 
covers  the  obturator  intemus  muscle  ;  the  other  internal,  or  superior,  which  passes  in- 
ward upon  the  side  of  the  prostate  gland,  bladder,  and  rectum,  in  the  male,  and  of  the 
bladder,  vagina,  and  rectum,  in  the  female,  in  order  to  form  the  floor  of  the  pelvis.  This 
IS  the  superior  pelvic  aponeurosis,  with  the  description  of  which  we  shall  commence. 

The  Superior  Pelvic  Aponeurosis,  or  Recto-vesical  Fascia. 

Dissection. — This  aponeurosis  must  be  studied  both  from  the  cavity  of  the  pelvis  and 
from  the  perineum.  It  is  exposed  in  the  pelvis  by  removing  the  peritoneum,  and  the 
loose  cellular  tissue  beneath  that  membrane :  this  should  be  done  without  any  cutting 
instiument.  To  view  this  fascia  from  the  perineum,  it  is  necessary  to  take  away  the 
adipose  tissue  that  occupies  the  perineal  fossae,  and  also  the  levator  ani  muscle. 

The  superior  pelvic  aponeurosis  forms  a  complete  floor  for  the  pelvis.  Anteriorly  it  is 
remarkable  for  its  strength  and  shortness  ;  in  fact,  it  does  not  reach  the  inlet  in  this  sit- 
uation, but  arises  on  each  side  from  the  symphysis  pubis,  presenting  the  appearance  of 
bands  or  columns,  which  are  more  or  less  separated  from  each  other,  and  become  at- 
tached to  the  front  of  the  neck  of  the  bladder,  whence  the  name  of  anterior  ligament  of 
the  bladder,  which  the  older  anatomists  gave  to  this  part  of  the  aponeurosis.  More  exter- 
nally, it  forms  a  strong  arch  (the  sub-pubic  arch),  which  completes  the  posterior  orifice  of 
the  obturator  or  sub-pubic  canal  (i,  fig.  48).  This  arch  is  not  unfrequently  double,  and 
then  one  of  the  foramina  gives  passage  to  vessels,  and  the  other  to  nerves. 

Still  more  externally,  it  is  attached  to  the  brim  of  the  pelvis,  in  the  manner  I  have  al- 
ready pointed  out. 

Posteriorly  it  is  extremely  thin,  passes  in  front  of  the  sciatic  plexus,  and  is  lost  upon 
the  sacrum.  Sometimes  it  appears  to  be  divided  into  two  lamina,  the  posterior  of  which 
passes  in  front  of  the  sciatic  plexus,  and  the  anterior  in  front  of  the  internal  ihac  vessels, 
to  which  it  would  seem  to  furnish  sheaths. 

Relations. — Its  upper  surface  is  concave,  and  connected  with  the  peritoneum  by  loose 
cellular  tissue,  containing  more  or  less  fat.  Its  lower  surface  is  convex,  and  covered  by 
the  levator  ani :  it  forms  part  of  the  great  perineal  excavation,  and  is  in  relation  with 
the  pjTiformis  and  obturator  intemus  mucles,  with  the  sacral  plexus,  &c. 

This  aponeurosis  is  perforated  by  a  great  number  of  openings  :  in  the  male  it  is  pierced 
by  the  prostate  {i,fiff.  181)  and  the  bladder  (h),  on  the  sides  of  which  it  is  prolonged,  and 
reflected  on  to  the  rectum,  whence  the  name  of  the  recto-vesical  aponeurosis,  given  to  it  by 
M.  Carcassone.  In  the  female  it  is  also  perforated  by  the  vagina.  On  each  side  of  the 
bladder  and  prostate  it  is  strengthened  by  two  tendinous  bands,  which  run  from  before 
backward.  These  are  sometimes  very  strong ;  they  extend  from  the  symphysis  pubis 
(6)  to  the  spine  of  the  ischium  (e),  pass  along  the  bladder  and  the  prostate,  and  are  re- 
flected upon  their  sides. 

In  front,  it  has  some  openings  for  the  vesical  and  prostatic  vessels. 

Behind  it  presents  a  considerable  opening,  which  corresponds  to  the  outlet  of  the  pel- 
vis, and  gives  passage  to  the  lumbo-sacral  nerve  and  the  gluteal  vessels.  The  extrem- 
ity of  the  arch  formed  by  it  corresponds  to  the  anterior  border  of  the  sciatic  notch.  It 
is  through  this  opening  that  sciatic  herniae  protrude. 

We  not  uncommonly  find  larger  or  smaller  openings  in  this  fascia,  of  an  oblong  or  cir- 
cular shape,  leading  into  conical  culs-de-sac,  which  are  filled  with  fat.  Lastly,  it  is  per- 
forated behind  by  the  ischiatic  and  internal  pudic  vessels.  It  does  not  appear  to  be  in- 
tended for  the  passage  of  the  vessels  which  are  distributed  in  the  interior  of  the  pelvis, 
for  it  seems  to  invest  these  in  fibrous  sheaths. 

Uses. — The  superior  pelvic  aponeurosis  forms  the  floor  of  the  pelvis ;  it  is  pushed 
downward  by  the  action  of  the  diaphragm  and  abdominal  muscles,  and  tends  to  prevent 
the  occurrence  of  perineal  herniae,  which  otherwise  would  be  extremely  common :  it 
forms  a  boundary  between  the  sub-peritoneal  and  the  perineal  cellular  tissue,  and  also 
limits  the  progress  of  inflammation  and  infiltrations.  Infiltration  of  urine  above  the  fas- 
cia can  only  be  caused  by  rupture  of  the  bladder  itself  The  prostate  {i,fig.  181)  is  al- 
most entirely  below  the  fascia,  and  therefore,  in  the  lateral  operation  for  stone,  in  which 
this  gland  is  the  principal  structure  to  be  divided,  inflammation  and  infiltration  of  the 
cellular  tissue  are  extremely  rare.  When  they  do  occur,  the  section  or  laceration  must 
have  been  prolonged  into  the  body  of  the  bladder. 

The  Lateral  Pelvic  Aponeurosis,  or  Fascia  of  the  Obturator  Muscle. 

Dissection. — ^This  aponeurosis  is  more  advantageously  studied,  at  least  in  its  most  impor- 
tant part,  from  the  perineum,  than  from  the  cavity  of  the  pelvis  :  it  is  exposed  on  either 
side  by  removing  the  adipose  tissue,  which  fills  up  the  perineal  fossa.  This  aponeurosis, 
which  is  quite  distinct  from  the  obturator  ligament,  commences  at  the  upper  part  of  the 
circumference  of  the  obturator  foramen,  and  at  the  brim  of  the  pelvis,  in  connexion  with 


THE  FEMORAL  APONEUROSIS.  30P 

the  superior  pelvic  aponeurosis,  which  it  soon  leaves,  and  is  applied  to  the  obturator  in- 
temus  muscle  :  it  then  unites  below  with  the  reflected  portion  of  the  great  sacro-sciatic 
ligament,  and  is  prolonged  upon  that  portion  of  the  anterior  surface  of  the  glutaeus  max- 
imus  which  projects  beyond  the  ligament,  and  also  upon  the  coccygeus  muscle. 

Relations. — On  the  inner  side  and  above,  it  is  only  separated  from  the  superior  pelvic 
aponeurosis  by  the  levator  ani,  which  is  applied  to  that  aponeurosis ;  lower  down,  the 
two  aponeuroses  are  separated  by  a  considerable  interval,  which  is  occupied  by  fat :  this 
interval  forms  the  perineal  fossa.  On  the  outside  it  is  in  contact  with  the  obturator  in- 
ternus,  and  lower  down  with  the  internal  pudic  vessels  and  nerves. 

Uses. — It  binds  down  the  obturator  internus  muscle,  and  protects  the  internal  pudic 
vessels  and  nerves,  which  are,  therefore,  rarely  cut  in  operations  in  the  perineum.  It 
forms  the  external  boundary  of  the  perineal  fossa. 

TTie  Perineal  Fosscb. — Situated  between  the  superior  pelvic  aponeurosis  (which  is  lined 
below  by  the  levator  ani)  and  the  lateral  pelvic  aponeurosis,  there  is  found  on  each  side 
of  the  anus  a  conical  space,  the  base  of  which  is  directed  downward,  and  corresponds 
to  the  skin :  it  is  formed  behind  by  the  lower  border  of  the  glutaeus  maximus  ;  in  front, 
by  the  transversus  perinei  muscle  ;  on  the  inside,  by  the  levator  ani  and  the  superior  pel- 
vic aponeurosis  ;  and  on  the  outside,  by  the  tuberosity  of  the  ischium.*  Each  of  these 
fossae  is  filled  by  a  large  quantity  of  fat,  and  traversed  by  fibrous  laminae,  some  of  which 
extend  vertically  from  the  apex  to  the  base,  and  divide  the  contained  adipose  ceUular 
tissue  into  several  distinct  portions.  When  an  abscess  occurs  in  either  of  these  fossae, 
it  may  be  easily  conceived  how  difficult  it  is  for  the  inner  surface  of  its  parietes  to  come 
into  opposition :  hence  the  pathology  of  fistulae,  and  the  modes  of  cure  which  are  adopted. 

The  Aponeuroses  of  the  Lower  Extremity. 
The  aponeuroses  of  the  lower  extremity  comprise  the  femoral  fascia ;  the  fascia  of  the 
leg ;  the  annular  ligaments,  which  bind  down  the  tendons  of  the  muscles  of  the  leg,  as 
they  are  passing  upon  the  dorsal  or  plantar  surface  of  the  foot ;  the  plantar  and  dorsal 
fascia  of  the  foot ;  and,  lastly,  the  fibrous  sheaths,  which  maintain  the  tendons  in  con- 
tact with  the  phalanges  of  the  toes.     We  shall  describe  these  in  succession. 

The  Femoral  Aponeurosis,  or  Fascia  Lata. 

After  the  remarks  which  we  have  already  made  upon  the  aponeuroses  generally,  it 
may  be  easily  conceived  that  the  muscles  of  the  thigh,  which  are  so  numerous,  of  such 
great  length,  and  so  loOsely  united  together,  and  almost  all  of  which  are  reflected  to  a 
greater  or  less  amount  over  the  knee,  require  to  be  kept  in  close  contact  with  each  oth- 
er and  with  the  bones  ;  hence  the  necessity  for  the  femoral' aponeurosis,  consisting  of  a 
large  fibrous  sheath,  that  confines  without  compressing  the  muscles,  and  the  strength  of 
which  is  directly  proportioned  to  the  force  of  the  muscles,  and  their  tendency  to  dis- 
placement. Its  superficial  or  sub-cutaneous  surface  {g  h,fig.  137)  is  separated  from  the 
skin  by  a  very  thin  fibrous  layer,  the  fascia  superficialis  (not  shown  in  fig.  137),  which 
can  be  more  easily  demonstrated  immediately  below  the  femoral  arch,  and  along  the  sa- 
phenous vein.  Between  the  femoral  aponeurosis  or  fascia  lata  and  this  superficial  fas- 
cia, which  results  from  the  union  of  the  fibrous  prolongations  given  off  by  the  deep  sur- 
face of  the  skin,  the  sub-cutaneous  vessels  and  nerves  take  their  course,  and  communi- 
cate with  the  deep  vessels  and  nerves,  either  by  simple  openings  or  by  fibrous  canals,  of 
variable  length.  Under  this  fascia,  also,  are  situated  the  superficial  lymphatic  vessels 
and  glands  of  the  groin. 

A  great  number  of  the  superficial  nerves  of  the  thigh  have  special  sheaths,  which  are 
hollowed  out,  as  it  were,  in  the  substance  of  this  aponeurosis. 

The  femoral  aponeurosis  is  perforated  with  a  great  number  of  foramina  opposite  the 
femoral  vessels,  from  Poupart's  ligament  to  the  entrance  of  the  vena  saphena  {x)  into 
the  femoral  vein  (y).  These  foramina,  which  occupy  a  triangular  space,  of  which  the 
base  is  above  and  the  apex  below,  are  intended  for  the '  passage  of  a  great  number  of 
lymphatic  vessels,  which  pass  through  it  to  join  the  deep  set.  This  has  been  called  the 
sieve-like  portion  of  the  fascia  lata,  or  the  fascia  cribriformis  (v) :  it  has  been  said  by  some, 
that  the  aponeurosis  is  altogether  wanting  in  this  situation.!  We  not  unfrequently  find 
a  lymphatic  gland  occupying  one  of  the  foramina. 

*  [These  spaces  are  the  ischio-recial  fossie  of  Velpeau  ;  they  are  described  by  him  as  if  lined  by  an  aponeu- 
rosis (the  ischio-rectal)  composed  of  two  layers,  one  external  or  ischiatic,  corresponding  to  the  lateral  pelvic 
aponeurosis  of  M.  Cruveilhier,  and  another  internal  or  rectal,  which  covers  the  lower  surface  of  the  levator 
ani  from  the  coccyx  to  the  posterior  border  of  the  transversus  perinei,  and  unites  with  the  other  layer  before, 
above,  and  behind.  This  latter  layer  is  very  thin,  and  continuous  with  the  united  margins  of  the  superficial 
perineal  fascia  and  the  triangular  ligament,  behind  the  transverse  muscle,  and  is  alluded  to  by  M.  Cruveilhier 
(p.  307)  as  a  reflection  of  the  superficial  fascia. 1 

t  [And  then  the  cribriform  fascia  is  regarded,  not  as  belonging  to  the  fascia  lata,  but  as  formed  by  a  deep 
layer  of  the  superficial  fascia,  situated  beneath  the  sub-cutaneous  vessels,  adherent  to  the  borders  of  the  saphe- 
nous opening  in  the  fascia  lata,  and  perforated  by  those  vessels.  The  saphenous  opening  is,  according  to  this 
view,  not  the  foramen  (t)  through  which  that  vein  passes,  but  the  aperture  (n)  left  between  the  iliac  (g)  and 
pubic  (A)  portions  of  the  fascia  lata,  and  is  bounded  externally  by  the  crescentic  margin  of  the  iliac  portion 
or  the  falciform  process  of  Bums  (see  the  left  side  of  Jiff.  137,  where  the  cribriform  fascia  has  been  enlirelj 
removed).] 


310  APONEUROLOGY. 

The  most  remarkable  of  all  these  openings  is  undoubtedly  that  (i)  for  the  vena  saphena 
interna,  where  that  vessel  enters  the  femoral  vein,  at  the  upper  part  of  the  thigh,  eight 
or  ten  lines  below  Poupart's  ligament.  The  margin  of  this  opening,  which  has  been 
improperly  called  the  inferior  orifice  of  the  crural  canal,  can  only  be  demonstrated  in  its  low- 
er half,  on  account  of  the  almost  complete  absence  of  the  aponeurosis  above  it :  this  is 
the  reason  of  the  semilunar  form  of  the  portion  of  the  fascia  over  which  the  vein  passes. 

The  deep  surface  of  the  fascia  lata  gives  off  a  great  number  of  prolongations,  which 
pass  between  the  muscles,  and  form  their  proper  investments  or  sheaths. 

The  largest  of  these  prolongations  form  two  lateral  septa,  called  the  inter-muscular  sep- 
ta, which  extend  from  the  fascia  to  the  linea  aspera ;  each  has  the  form  of  a  triangle, 
having  its  base  directed  downward  and  its  apex  upward ;  they  are  extremely  thick,  es- 
pecially below. 

The  Inter-muscular  Septa  of  the  Femoral  Aponeurosis. 

Of  these  there  are  two,  one  internal  and  the  other  external. 

The  Internal  Inter-muscular  Septum. — This  serves  at  once  as  a  septum,  an  aponeurosis 
of  insertion,  and  a  sheath  for  the  vastus  intemus :  it  extends  from  the  anterior  inter- 
trochanteric line  to  the  inner  condyle  of  the  femur. 

Its  anterior  surface  affords  attachments  to  the  vastus  intemus  throughout  its  whole 
extent :  its  posterior  surface  is  in  opposition  with  the  adductors,  and  is  intimately  uni- 
ted to  their  aponeuroses.  Its  outer  margin  is  attached  to  the  Unea  aspera :  its  inner 
margin  is  very  thick,  and  prominent  below,  where  it  is  strengthened  by  the  inferior  ten- 
don of  the  adductor  magnus,  and  may  be  felt  under  the  skin  like  a  cord.  It  appears  to 
become  continuous  below  with  the  internal  later£il  ligament  of  the  knee. 

It  is  composed  of  very  strong  vertical  fasciculi,  passing  somewhat  obliquely  down- 
ward and  inward.  These  fasciculi  are  bound  together  above  the  inner  condyle  by  oth- 
ers passing  transversely,  and  are  crossed  almost  at  right  angles  by  the  tendinous  fibres 
of  the  adductors. 

Lastly,  the  internal  septimi  is  perforated,  near  the  linea  aspera,  by  a  number  of  orifices 
destined  for  the  passage  of  vessels,  and  forming  communications  between  the  anterior 
and  the  internal  sheath  of  the  muscles  of  the  thigh. 

The  External  Inter-muscular  Septum. — This  serves  as  a  septum,  an  aponeurosis  of  in 
sertion,  and  as  a  sheath  for  the  vastus  extemus. 

It  extends  from  the  great  trochanter  to  the  external  condyle,  above  which  it  forms  a 
projecting  cord :  it  affords  attachments  to  the  vastus  extemus  in  front,  and  to  the  short 
head  of  the  biceps  behind. .  Its  inner  margin  is  attached  to  the  linea  aspera :  its  outer 
margin  forms  a  prominent  cord,  especially  below. 

It  consists  of  fibres  directed  vertically,  or  somewhat  obliquely  outward,  and  strength- 
ened by  transverse  fibres  above  the  condyle.  Like  the  internal  septum,  it  is  perforated, 
especially  above  and  below :  above,  for  the  passage  of  the  circumflex  vessels ;  below, 
for  the  passage  of  the  articular  vessels  of  the  knee. 

We  shall  now  examine  the  different  sheaths  fiirnished  by  the  femoral  aponeurosis. 
One  of  the  most  important  of  these  is,  as  it  were,  hollowed  out  of  the  sides  of  the  others, 
and  belongs  to  the  femoral  vessels. 

The  Sheath  of  the  Femoral  Vessels. 

The  femoral  artery  (z,fig.  137)  and  vein  (y)  are  enclosed  in  a  prismatic  and  triangular 
tendinous  canal,  which  protects  them  in  their  course  amid  the  muscles  of  the  thigh. 
The  portion  of  the  canal  (laid  open  in  fig.  137)  included  between  the  femoral  arch  and 
the  point  where  the  vena  saphena  opens  into  the  femoral  vein,  has  received  the  name 
of  the  crural  canal,  a  term  to  which  I  have  always  objected,  since  it  was  first  introduced 
into  anatomical  nomenclature,  because  it  establishes  a  false  analogy  between  the  ingui- 
nal canal  and  this  upper  portion  of  the  sheath  of  the  femoral  vessels ;  for,  while  an 
oblique  inguinal  hernia  traverses  the  entire  length  of  the  inguinal  canal,  crural  herniae, 
as  far,  at  least,  as  my  own  observation  extends,  never  protrude  through  the  saphenous 
opening,  but  escape  inunediately  below  the  femoral  arch,  and  lift  up  the  cribriform  por- 
tion of  the  fascia  lata.* 

The  anterior  wall  of  the  sheath  of  the  femoral  vessels  is  formed  above  by  the  cribri- 
form portion  of  the  femoral  fascia  (g',fig.  137),  then  by  the  fascia  itself,  and,  lastly,  by 
the  posterior  layer  of  the  sheath  of  the  sartorius,  in  which  place  it  is  thin  and  transparent. 

Tlie  internal  wall  is  formed  above  by  the  very  strong  layer  covering  the  pectineus  ;  be- 
low, by  the  weaker  layer  investing  the  adductors. 

The  external  wall  consists  of  the  very  strong  sheath  {s',fig:  136)  of  the  psoas  and  ilia- 
cus  :  externally  to  this  wall  is  situated  the  crural  nerve,  a  branch  of  which  perforates 

*  [The  tenn  "crural  ring"  is,  in  this  country,  commonly  limited  to  the  space  (r,fig.  136)  situated  internal- 
ly to  the  femoral  vein.  By  the  term  "  crural  canal"  is  generally  understood  that  portion  only  of  the  canal  de- 
scribed by  M.  Cruveilhier  as  the  "  craral  canal,"  which  is  situated  on  the  inner  side  of  the  femoral  vein,  and 
is  occupied  by  cellular  tissue,  lymphatic  vessels,  and  sometimes  by  a  lymphatic  gland.  If  the  term  crural  ca- 
nal be  thus  defined,  if  the  cribriform  fascia  be  regarded  as  a  part  of  the  superficial  fascia,  and  the  saphenous 
aperture  as  the  space  between  the  iliac  and  pubic  portions  of  the  fascia  lata  (see  note,  p.  309),  the  analogy  be- 
tween the  crural  and  inguinal  canals  will  not  be  so  very  remote.] 


THE    FEMORAL    APONEUROSIS.  81 J 

the  sheath  and  joins  the  vessels.    Lower  down,  the  external  wall  is  formed  by  the  apo 
neurosis  of  the  vastus  internus. 

The  three  great  Muscular  Sheaths  of  the  Femoral  Aponeurosis. 

By  means  of  the  internal  and  external  inter-muscular  septa,  the  muscles  of  the  ante- 
rior region  of  the  thigh  are  separated  from  those  of  the  posterior  and  internal  regions  ; 
a  weaker  septum  than  the  preceding  intervenes  between  the  muscles  of  the  internal 
and  posterior  regions.  It  foUows,  then,  that  the  femoral  aponeurosis  presents  three 
great  tendinous  sheaths  :  an  anterior,  an  internal,  and  a  posterior. 

The  great  posterior  sheath  is  undivided :  it  is  common  to  the  biceps,  the  semi-tendino- 
sus,  and  the  semi-membranosus. 

The  great  anterior  and  internal  sheaths  are  subdivided  into  a  number  of  secondary 
uheaths,  in  most  cases  corresponding  with  the  number  of  the  muscles. 

The  great  Anterior  Sheath. — The  sartorius  has  a  proper  sheath,  remarkable  for  its  pris- 
matic and  triangular  form.  The  rectus  femoris,  or  long  head  of  the  triceps,  is  separated 
from  the  two  vasti  by  a  tendinous  layer,  very  thin  below,  but  strong  above,  and  com- 
posed of  vertical  fibres. 

The  tensor  vaginae  femoris  is  contained  in  the  strongest  sheath  in  the  human  body, 
for  it  is  formed  by  the  fascia  lata  itself  The  deep  layer  of  this  sheath  is  much  thinner 
than  the  superficial ;  it  commences  at  the  anterior  inferior  spinous  process  of  the  ilium, 
below  the  rectus,  and  may  be  regarded  eis  the  deep  origin  of  the  ^road  band  in  which 
the  tensor  vaginae  femoris  terminates :  it  is  composed  of  verticed  fibres,  prolonged  be- 
tween the  rectus  and  the  vastus  externus.  Lastly,  above  and  on  the  outside,  we  find 
the  sheath  of  the  psoas  and  iliacus  {s',fig.  136),  which  forms  a  continuation  of  the  lum- 
bo-iliac  aponeurosis,  or  fascia  iliaca. 

The  great  internal  sheath  furnishes  a  number  of  tendinous  lamellae,  which  separate  the 
different  muscles  of  this  region.  Thus,  there  is  a  proper  sheath  for  the  gracilis,  a  com- 
mon one  for  the  pectineus  and  the  adductor  longus,  one  for  the  adductor  brevis,  and  an- 
other for  the  adductor  magnus.  The  sheath  of  the  obturator  externus  is  continuous 
with  that  of  the  adductor  brevis  ;  it  commences  by  a  very  strong  fibrous  lamina  or  arch, 
which  arises  from  the  anterior  edge  of  the  pubes,  and  is  directed  obhquely  outward  to 
the  fibrous  capsule  of  the  hip-joint.  This  arch  conceals  the  anterior  orifice  of  the  obtu- 
rator canal,  and  protects  the  obturator  vessels  and  nerves. 

Lastly,  the  two  vasti,  which  extend  into  all  the  regions  of  the  thigh,  have  sheaths 
formed  by  the  femoral  fascia,  where  they  are  superficial,  and  by  the  internal  and  exter- 
nal inter-muscular  septa,  and  the  posterior  laminae  of  the  other  sheaths  in  their  more 
deeply-situated  portions. 

In  the  midst  of  the  sheaths  of  the  anterior  and  internal  regions  we  find  the  sheath  of 
the  femoral  vessels  already  described. 

The  Superior  Circumference  of  the  Femxiral  Aponeurosis. 

In  front  the  femoral  aponeurosis  arises  from  the  femoral  arch,  with  which  it  is  so  pei- 
fectly  continuous  as  to  render  the  arch  tense :  hence  the  plan,  already  mentioned  as 
proposed  by  Scarpa,  of  endeavouring  to  remove  the  constriction  in  cases  of  strangulated 
crural  hernia,  by  puncturing  the  femoral  aponeurosis. 

But  the  mode  of  origin  and  continuity  of  this  fascia  with  the  femoral  arch  is  not  the 
same  on  the  inner  and  outer  sides.  On  the  outside,  the  iliac  portion  of  the  femoral  apo 
neurosis  (g,  fig.  137)  arises  by  a  single  very  thick  layer ;  more  internally,  in  the  situation 
of  the  femoral  vessels,  it  arises  by  two  layers,  one  superficial,  thin,  and  perforated  by 
foramina  (the  cribriform  portion,  v) ;  the  other  deep,  called  its  pubic  portion  (A),  which  is 
continuous  with  the  fascia  iUaca  (s,fig.  136),  covers  the  pectineus,  and  sends  off  a  pro- 
longation between  that  muscle  and  the  psoas.  This  deep  layer  forms  the  posterior  wall 
of  the  canal  of  the  femoral  vessels. 

On  the  inside  of  the  thigh,  the  femoral  aponeurosis  arises  from  the  body  of  the  os  pu- 
bis and  the  ascending  ramus  of  the  ischium. 

On  the  outside  and  behind,  it  arises  from  the  crest  of  the  ilium  by  very  numerous  ver- 
tical fibres,  which  are  strengthened,  especially  behind,  by  other  horizontal  fibres.  Be- 
tween the  posterior  superior  spine  of  the  ilium  and  the  crest  of  the  sacrum  there  is  a 
tendinous  arch,  which  is  common  to  the  femoral  fascia  and  the  aponeurosis  of  the  long 
muscles  of  the  back. 

The  Glutceal  Aponeurosis. 
The  glutaeal  aponeurosis  forms  the  upper  and  back  part  of  the  femoral  fascia.  It  cov- 
ers the  glutaeus  medius,  in  which  situation  it  is  extremely  thick,  and  is  continuous  with 
the  broad  band  of  the  tensor  vaginae  femoris.  Having  reached  the  upper  border  of  the 
glutaeus  maximus,  it  is  divided  into  two  layers  :  one  superficial  and  very  thin,  which 
covers  the  outer  surface  of  the  gluta;us  maximus,  becomes  thinner  below,  and  continu- 
ous with  the  femoral  fascia ;  the  other  deep  and  thicker,  especially  above  and  behind, 
where  it  affords  attachment  to  the  glutaeus  maximus,  and  is  blended  with  the  great  sa- 
cro-sciatic  ligament.     It  becomes  ver}'  thin  whe:  e  it  separates  the  gluta3us  maxirau? 


312  APONEUROLOGY. 

from  the  deep-seated  muscles.    A  synovial  capsule  intervenes  between  this  fascia  and 
the  great  trochanter,  and  another  between  it  and  the  tuberosity  of  the  ischium. 

It  presents  a  very  remarkable  opening  called  the  glutaal  arch,  for  the  passage  of  the 
glutseal  vessels  and  nerves.  Lastly,  over  that  portion  of  the  glutaeus  maximus  which 
enters  into  the  formation  of  the  corresponding  perineal  fossa,  it  acquires  a  great  degree 
of  thickness,  and,  at  the  lower  border  of  the  muscle,  is  blended  with  the  superficial  layer 
of  the  gluteal  fascia. 

The  Inferior  Circumference  of  the  Femoral  Aponeurosis. 

The  femoral  aponeurosis  terminates  below,  around  the  knee-joint,  where  it  becomes 
continuous,  partly  with  the  fascia  of  the  leg,  and  partly  with  the  fibrous  structures  cov- 
ering this  articulation.  Concerning  the  arrangement  of  these  fibrous  laminae  we  shall 
offer  a  few  remarks. 

Behind,  the  femoral  aponeurosis  passes  over  the  popliteal  space,  and  is  continuous 
with  the  fascia  of  the  leg. 

In  front,  it  is  prolonged  over  the  patella,  from  which  it  is  separated  by  a  synovial  bur- 
sa; it  is  very  thin,  and  is  continued  in  front  of  the  ligament  of  the  patella,  upon  which 
it  forms  a  thin  layer  of  transverse  fibres. 

071  the  inside,  it  is  at  first  blended  with  the  sheath  of  the  sartorius,  and  then  with  the 
horizontal  portion  of  the  tendon  of  this  muscle  ;  it  crosses  the  fibres  of  that  portion  per- 
pendicularly, and  becomes  continuous  with  the  fascia  of  the  leg. 

Under  this  layer  of  fibrous  tissue  we  find,  on  the  inside  of  the  knee,  another  very  dense 
layer,  formed  by  vertical  tendinous  fibres  derived  from  the  vastus  internus,  and  inserted 
into  the  upper  part  of  the  inner  surface  of  the  tibia,  beneath  the  tendon  of  the  sartorius. 
This  fibrous  layer,  which  may  be  regarded  as  the  lower  or  tibial  insertion  of  the  vastus 
extemus,  occupies  the  interval  between  the  internal  lateral  ligament  of  the  knee-joint 
and  the  patella.  Its  vertical  fibres  are  crossed  by  others  at  right  angles,  extending  from 
tne  internal  tuberosity  of  the  femur  to  the  corresponding  margin  of  the  patella. 

Lastly,  under  this  we  find  another  very  thin  layer,  belonging  to  the  synovial  capsule. 

On  the  outside,  the  femoral  aponeurosis  is  blended  with  the  broad  band  of  the  tensor 
vaginae  femoris,  from  which  it  can  be  distinguished  only  by  the  horizontal  direction  of 
its  fibres. 

Beneath  this  very  thick  layer  we  find  a  thin  one,  composed  of  fibres  stretching  from 
the  external  tuberosity  of  the  femur  to  the  patella ;  and,  lastly,  another  thin  layer  be- 
longing to  the  synovial  membrane. 

Structure  of  the  Femoral  Aponeurosis. 

It  is  thin  behind  and  on  the  inside,  thicker  in  front,  and  extremely  thick  on  the  out- 
side of  the  thigh,  where,  indeed,  it  may  be  said  to  exceed  all  other  fibrous  membranes  in 
thickness  and  in  strength.  This  thickened  portion  is  bounded  in  front  by  a  line  extend- 
ing vertically  downward  from  the  anterior  superior  spinous  process  of  the  ilium.  Its  lim- 
its behind  are  no  less  distinctly  defined  ;  hence  the  name  given  to  it  of  the  broad  hand 
{fascia  lata). 

This  great  density  is  owing  to  some  very  strong  vertical  fibres,  arising  from  the  front 
of  the  crest  of  the  ilium.  It  is  connected  with  the  great  force  and  tendency  to  displace- 
ment of  the  vastus  externus. 

We  may  add,  that  the  femoral  aponeurosis  is  composed  of  horizontal  fibres,  sometimes 
regularly  parallel,  as  in  its  thinnest  portions,  and  sometimes  intersecting  each  other. 
These  horizontal  fibres  are  even  seen  opposite  the  broad  band  on  the  outer  side,  from 
which  they  are  distinguished  by  their  direction. 

There  is  a  very  beautiful  preparation  of  this  aponeurosis  in  the  Museum  of  the  Facul- 
ty of  Medicine  :  similar  preparations  should  be  made  by  those  who  wish  to  obtain  a  good 
idea  of  the  tendinous  sheaths,  and  the  shape  of  the  muscles  of  the  thigh.  It  is  to  be 
made  by  removing  all  the  muscles  from  their  sheaths  by  means  of  longitudinal  incisions, 
and  substituting  for  them  a  quantity  of  tow,  which  must  be  taken  out  when  the  aponeu- 
roses are  completely  dried.  The  form  of  the  sheaths  exactly  represents  that  of  the  cor- 
responding muscles.  A  tolerably  accurate  idea  of  these  sheaths  may  also  be  obtained 
by  cutting  across  each  sheath  and  the  muscle  which  it  contains,  in  a  fresh  subject.  The 
circumference  of  the  section  of  the  portion  of  the  sheath  that  becomes  visible  after  the 
retraction  of  the  muscle  will  give  an  excellent  idea  of  the  figure  of  the  different  sheaths, 
which  are  all  angular  and  polyhedral  like  the  muscles,  but  never  rounded  :  during  health 
they  are  completely  filled  by  the  muscles,  which  in  emaciated  persons,  on  the  contrary, 
do  not  occupy  more  than  a  half,  a  third,  or  a  sixth  of  the  area  of  their  sheaths. 

Such  is  the  femoral  fascia.  Its  tensor  muscles  consist  of  the  tensor  vaginae  femoris  and 
the  glutaeus  maximus,  the  tendon  of  which  is  received  between  two  layers  of  this  fascia. 

Aponeuroses  of  the  Leg  and  Foot. 
Aponeurosis  of  the  Leg. 
The  aponeurosis  of  the  leg  forms  a  strong  general  investment  for  the  whole  leg,  except- 


ANNULAR  LIGAMENTS  OF   THE   TARSUS.  313 

mg  the  internal  surface  of  the  tibia,  which  is  covered  by  it  only  at  its  lower  part,  a  little 
above  the  malleoli. 

Its  external  surface  is  separated  from  the  skin  by  the  superficial  vessels  and  nerves, 
several  of  which  perforate  it,  either  directly,  or  after  having  run  for  a  short  distance  in  its 
substance.     The  external  saphenous  vein  and  nerve  receive  from  it  a  complete  sheath. 

Its  internal  surface  covers  all  the  muscles  of  the  leg,  and  does  not  adhere  to  them  ex- 
cepting above  and  in  front,  where  it  gives  attachment  to  the  tibialis  anticus  and  the  ex- 
tensor communis  digitorum.  From  the  internal  surface  there  proceeds  on  the  outer  side 
of  the  leg  two  principal  tendinous  septa,  one  situated  between  the  muscles  of  the  ante- 
rior tibial  region  and  the  peronei,  the  otlier  between  the  peronei  and  the  muscles  of  the 
posterior  region  of  the  leg.  There  are,  therefore,  three  principal  sheaths  in  the  leg,  an 
anterior,  an  internal,  and  a  posterior.  The  latter  is  subdivided  into  two  other  sheaths 
by  a  very  strong  transverse  lamina,  becoming  still  stronger  below,  which  separates  the 
muscles  of  the  deep  posterior  layer  and  the  posterior  tibial  and  peroneal  vessels  and 
nerves  from  the  superficial  layer  of  muscles,  or  the  triceps  suralis.  Lastly,  some  tendi- 
nous laminae,  more  or  less  complete,  are  interposed  between  the  different  muscles  of 
each  region.  Thus,  a  tendinous  layer  separates  the  tibialis  anticus,  at  first  from  the  ex- 
tensor communis  digitorum,  and  then  from  the  extensor  proprius  pollicis  :  this  layer  dis- 
appears in  the  middle  of  the  leg.  Another  very  strong  tendinous  lamina  separates  the 
tibialis  posticus  from  the  flexor  longus  digitorum  on  the  one  hand,  and  from  the  flexor 
longus  pollicis  on  the  other. 

Superior  Circumference. — If  we  now  examine  the  manner  in  which  the  aponeurosis 
of  the  leg  becomes  continuous  with  that  of  the  thigh,  we  shall  find  that,  posteriorly,  the 
femoral  fascia  is  prolonged  directly  upon  the  leg,  in  order  to  form  the  posterior  part 
of  its  aponeurosis,  which,  in  this  situation,  also  receives  an  expansion  from  the  ten- 
dons of  the  biceps,  sartorius,  gracilis,  and  semi-tendinosus,  and  from  the  broad  band  of 
the  fascia  of  the  thigh.  Anteriorly  the  fascia  of  the  leg  is  continous  with  that  of  the 
thigh  over  the  patella,  and  appears  also  to  arise  directly  from  the  outer  edge  of  the  ante- 
rior tuberosity  of  the  tibia,  from  the  head  of  the  fibula,  and  from  the  tendon  of  the  biceps, 
which,  as  we  have  already  seen,  gives  off  an  aponeurotic  expansion  backward. 

By  its  lower  circumference  this  fascia  is  continuous  with  the  annular  ligaments  of  the 
ankle,  which  we  shall  presently  describe. 

Structure. — On  examining  the  direction  of  the  fibres  and  the  thickness  of  the  fascia  of 
the  leg,  it  is  found  that  it  is  much  thicker  in  front  than  on  the  outer  side  of  the  leg,  and 
still  more  so  than  behind ;  that,  in  the  first  situation,  in  the  ujpper  three  fourths  of  its  ex- 
tent, it  is  composed  of  obliquely  interlaced  fibres,  some  of  which  descend  from  the  spine 
of  the  tibia,  and  others  from  the  anterior  angular  surface  of  the  fibula  ;  and  that  in  the 
lower  fourth  of  the  anterior  region  of  the  leg,  and  in  the  whole  extent  of  the  posterior  re- 
gion, it  is  composed  of  circular  fibres. 

At  the  point  where  the  muscles  of  the  leg  become  tendinous,  and  are  reflected  over 
the  ankle,  they  require  very  strong  sheaths  to  keep  them  in  contact  with  the  joint ;  the 
fascia  of  the  leg,  therefore,  forms,  opposite  this  part,  the  anterior,  internal,  and  external 
annular  ligaments. 

The  Annular  Ligaments  of  the  Tarsus. 

The  annular  ligaments  of  the  tarsus  are  three  in  number :  an  anterior  or  dorsal,  an  in- 
ternal, and  an  external. 

The  dorsal  annular  ligament  of  the  tarsus.  The  aponeurosis  of  the  leg  is  thicker  at  the 
lower  and  anterior  part  of  the  leg,  and  binds  down  the  corresponding  portion  of  the  mus- 
cles in  that  region.  But  there  is,  in  addition  to  this,  a  dorsal  annular  ligament  of  the 
tarsus  (see  fig.  128),  which  arises,  by  a  narrow  but  thick  extremity,  in  front  of  the  as- 
tragalo-calcanean  fossa,  becomes  broader  as  it  extends  inward,  and  is  divided  into  two 
bands.  The  superior  band  passes  upward  and  inward  above  the  internal  malleolus,  and 
is  split  into  two  layers,  in  such  a  way  as  to  form  two  complete  sheaths  :  one  internal, 
for  the  tibialis  anticus ;  the  other  external,  for  the  extensor  longus  digitorum  and  the 
peroneus  tertius.  Between  these  two  complete  sheaths,  which  are  separated  from  the 
synovial  capsule  of  the  joint  by  a  layer  of  cellular  tissue,  we  find  an  incomplete  sheath 
(for  the  annular  ligament  is  not  split  into  two  layers  in  this  situation),  intended  for  the 
extensor  proprius  pollicis  and  the  anterior  tibial  vessels  and  nerves  :  the  internal  sheath  is 
the  higher,  and  situated  opposite  the  lower  extremity  of  the  tibia  ;  the  external  sheath 
is  lower,  and  corresponds  to  the  ankle-joint.  The  inferior  band,  or  the  lower  bifurcation 
of  the  annular  ligament,  passes  forward  and  inward  to  the  front  of  the  tarsus,  and  be- 
comes continuous  with  the  internal  plantar  aponeurosis.  This  lower  band  forms  a  sec- 
ond annular  ligament,  which  furnishes  to  each  of  the  three  preceding  muscles,  upon  the 
dorsum  of  the  foot,  a  less  powerful  sheath  than  that  afforded  by  the  upper  band  :  it  keeps 
the  tendons  closely  applied  to  the  bones. 

The  external  and  internal  annular  ligaments  of  the  tarsus  are  two  fibrous  bands,  contin- 
uous with  the  fascia  of  the  leg  on  the  one  hand,  and  with  the  plantar  aponeurosis  on  the 
other. 

Rr 


i 


314  APONEUROLOGY. 

The  internal  annular  ugament  arises  from  the  borders  and  summit  of  the  internal  mal- 
leolus, and  proceeds  in  a  radiating  manner  to  the  inner  side  of  the  os  calcis,  and  the  in- 
ner margin  of  the  internal  plantar  aponeurosis.  Beneath  this  sheath,  which  is  thick- 
er below  than  above,  and  closes  in  the  concavity  on  the  inner  surface  of  the  os  cal- 
cis, proceed  the  posterior  tibial  vessels  and  nerves,  and  also  the  tendons  of  the  tibialis 
posticus,  the  flexor  longus  digitorum,  and  the  flexor  longus  poUicis.  For  these  several 
parts  there  are  four  very  distinct  sheaths  :  the  most  superficial  is  that  for  the  vessels 
and  the  nerves  ;  two  sheaths,  placed  one  over  the  other  (see  Jig.  130),  and  behind  the 
internal  malleolus,  belong,  the  anterior  to  the  tibialis  posticus  (w),  and  the  posterior  or 
more  superficial  to  the  flexor  longus  digitorum  (o).  These  two  sheaths  soon  separate 
as  the  two  tendons  diverge  from  each  other  towards  their  insertions  :  as  the  sheath  of 
the  tibialis  posticus  is  continued  as  far  as  the  insertion  of  that  muscle,  the  sheath  of  the 
flexor  longus  digitorum  accompanies  it  to  where  it  gets  beneath  {i.  e.,  deeper  from  the 
surface  than)  the  plantar  fascia.  The  sheath  of  the  flexor  longus  pollicis  {p)  is  lower 
than  the  preceding,  and  extends  obliquely  along  the  astragalus  and  os  calcis,  to  be  cov- 
ered by  the  internal  plantar  fascia. 

The  external  annular  ligament  forms  a  common  sheath  for  the  two  peronei,  longus  et 
brevis :  it  extends  from  the  border  of  the  external  malleolus  to  the  os  calcis,  and  is 
completed  on  the  inside  by  the  external  lateral  ligaments.  It  is  at  first  single,  but  soon 
becomes  subdivided  into  two  other  sheaths,  one  of  which  is  destined  for  the  tendon  of 
the  peroneus  brevis,  and  the  other  for  that  of  the  peroneus  longus. 

The  Aponeuroses  of  the  Foot. 

These  are  divided  into  the  dorsal  and  plantar. 

The  Dorsal  Aponeuroses  of  the  Foot. 

These  comprise  the  dorsal  aponeurosis,  properly  so  called,  the  pedal  aponeurosis  (Vapo- 
neurose  pidieuse),  and  the  dorsal  interosseous  aponeuroses. 

Dorsal  Aponeurosis  of  the  Foot. — While  the  upper  margin  of  the  annular  ligament  is 
blended  with  the  fascia  of  the  leg,  which  appears  to  be  inserted  upon  it,  the  anterior 
margin  of  the  same  ligament  becomes  continuous  with  the  dorsal  aponeurosis  of  the  foot. 
This  dorsal  aponeurosis  is  a  thin  layer,  which  forms  a  general  sheath  for  all  the  tendons 
situated  upon  the  dorsum  of  the  foot :  it  gradually  disappears  in  front,  opposite  the  an- 
terior extremities  of  the  metatarsal  bones,  and  is  attached  at  the  sides  to  the  borders 
of  the  foot,  becoming  continuous  with  the  plantar  fascia.  These  tendons,  again,  are  sep- 
arated from  the  extensor  brevis  digitorum  by  another  and  still  thinner  layer,  which  in- 
vests that  muscle  :  this  is  the  pedal  aponeurosis  ;  lastly,  upon  the  same  surface  of  the 
foot  we  find  the  four  dorsal  interosseous  aponeuroses,  viz.,  one  for  each  interosseous  space. 
The  Plantar  Aponeuroses. 

The  plantar  aponeuroses  or  fasciae  are  three  in  number :  one  middle,  the  other  two 
lateral. 

The  middle  plantar  aponeurosis  is  very  strong,  is  attached  to  the  inner  of  the  posterior 
tubercles  of  the  calcaneum,  becomes  suddenly  contracted,  and  afterward  gradually  ex- 
pands without  diminishing  perceptibly  in  thickness.  Opposite  the  anterior  extremities 
of  the  metatarsal  bones,  it  divides  into  four  bands,  which  are  themselves  bifurcated  al- 
most immediately,  so  as  to  embrace  the  flexor  tendons  of  the  four  outer  toes.  Becom- 
ing moulded  on  the  sides  of  these  tendons,  they  furnish  those  of  each  toe  with  an  almost 
complete  sheath,  which  is  attached  to  the  upper  and  lateral  borders  of  the  anterior  gle- 
noid ligament  of  the  corresponding  metatarso-phalangal  articulation,  and  becomes  con- 
tinuous with  the  tendinous  sheath  of  the  corresponding  toe.  These  four  sheaths  are 
separated  by  three  arched  openings,  through  which  proceed  the  lumbricales  and  interos- 
seous muscles,  and  the  plantar  vessels  and  nerves.  There  is  a  perfect  analogy  between 
the  middle  plantar  and  the  middle  palmar  aponeurosis ;  but  the  former  is  by  far  the 
stronger.  It  constitutes,  indeed,  a  true  ligament  for  the  foot,  offers  a  powerful  resist- 
ance to  the  forced  extension  of  the  phalanges  upon  the  bones  of  the  metatarsus,  and  sup- 
ports the  antero-posterior  arch  of  the  sole  of  the  foot.  I  have  known  exceedingly  vio- 
lent pain  to  be  produced  by  distension,  and,  probably,  laceration  of  some  of  the  fibres  of 
this  aponeurosis.  The  margins  of  the  middle  plantar  aponeurosis  are  curved  upward, 
so  as  to  embrace  the  flexor  brevis  digitorum  on  each  side ;  they  become  continuous 
with  the  external  and  internal  plantar  aponeuroses,  and  form  septa  between  the  muscles 
of  the  middle  and  those  of  the  external  and  internal  plantar  regions  :  in  front  these  septa 
are  complete,  but  only  partial  behind.  The  upper  surface  of  this  fascia  gives  attach- 
ment, posteriorly,  to  the  short  flexor  of  the  toes  :  the  proper  tendinous  expansion  of  this 
muscle  appears  to  be  given  otf  from  the  upper  surface  of  the  plantar  aponeurosis. 

Some  transverse  fibres  strengthen  this  fascia  in  front,  and  I  shall  also  notice  some 
other  transverse  fibres,  perfectly  distinct  from  the  preceding,  which  form  a  true  trans- 
verse ligament  for  the  four  outer  toes  :  it  is  situated  opposite  the  middle  of  the  lower 
surface  of  the  first  phalanges,  and  is  admirably  adapted  for  opposing  their  dislocation. 

The  External  and  Internal  Plantar  Aponeuroses. — The  external  plantar  aponeurosis,  very 


THE  APONEUROSES  OF  THE  SHOULDER.  315 

thick  behind  and  thin  in  front,  gives  attachment  by  its  upper  surface  to  the  abductor 
muscle  of  the  Httle  toe,  and  is  bifurcated  at  the  posterior  extremity  of  the  fifth  metatar- 
sal bone.  The  external  division  of  this  bifurcation  is  very  strong,  is  inserted  into  the 
enlarged  posterior  extremity  of  the  fifth  metatarsfd  bone,  and  may  be  regarded  as  a  pow- 
erful medium  of  connexion  between  that  bone  and  the  cuboid.  The  internal  plantar  apo- 
neurosis is  thin  in  comparison  with  the  external ;  it  commences  behind  by  an  arch,  ex- 
tending from  the  inner  malleolus  to  the  os  calcis  ;  its  inner  margin  is  attached  to  the 
corresponding  border  of  the  tarsus,  and  is  continuous  with  the  dorsal  annular  ligament 
and  with  the  dorsal  fascia  of  the  foot ;  its  outer  margin  is  blended  with  the  middle  plan- 
tar fascia,  or,  rather,  is  reflected  upward,  to  complete  the  sheath  for  the  internal  mus- 
cles of  the  foot. 

These  three  plantar  fasciae  just  described  form  three  sheaths,  which  are  quite  distinct 
in  their  anterior  five  sixths,  but  communicate  with  each  other  behind. 

The  internal  plantar  sheath  includes  the  abductor  and  the  short  flexor*  of  the  great 
toe,  which  are  separated  from  each  other  by  a  layer  of  fibrous  tissue  ;  it  also  contains 
the  internal  plantar  artery  and  nerves. 

The  external  plantar  sheath  includes  the  abductor  and  the  flexor  of  the  little  toe,  Avhich 
are  also  separated  by  a  tendinous  layer.  Lastly,  the  middle  plantar  sheath  includes  the 
short  flexor  of  the  toes,  the  tendon  of  the  flexor  longus  digitorum,  the  flexor  accesso- 
rius,  the  lumbricales,  the  tendon  of  the  flexor  longus  poUicis,  the  oblique  adductor,!  the 
transversus  pedis,  and  the  external  plantar  vessels  and  nerves.  The  sheath  of  the 
flexor  brevis  digitorum  is  completed  above  by  an  aponeurotic  layer,  which  separates  it 
from  the  tendons  of  the  long  flexor  and  from  the  accessorius.  A  prope\'  sheath  exists 
for  the  oblique  adductor,+  and  a  subdivision  of  the  same  sheath  for  the  transverse  ad- 
ductor. It  is  formed  above  by  the  interosseous  aponeuroses,  and  below  by  a  thin  layer 
attached  to  the  circumference  of  the  deep  hollow  in  which  the  adductors  are  lodged. 
Lastly,  the  inferior  interosseous  aponeurosis  is  remarkable  for  its  thickness,  and  for  the 
septa  which  it  gives  off  between  the  interosseous  muscles. 

The  sheaths  into  which  the  flexor  tendons  of  the  toes  are  received  opposite  the  pha- 
langes resemble  so  exactly  those  of  the  fingers,  that  I  shaU  not  anticipate  what  will  be 
said  hereafter  regarding  the  latter.  We  find  the  same  system  of  synovial  membranes, 
and  the  same  loose,  membranous,  and  extensible  cellular  tissue  for  the  flexor  tendons 
of  the  toes  as  for  those  of  the  fingers.  In  all  sheaths  that  are  partly  osseous  and  partly 
tendinous,  we  find  a  synovial  membrane  ;t  but,  on  the  other  hand,  there  is  nothing  more 
than  a  loose  cellular  tissue  in  situations  where  a  tendon  or  muscle  ghdes  in  the  interior 
of  a  confining  aponeurosis. 

The  Aponeuroses  of  the  Upper  Extremity. 

Tliese  comprise  the  aponeuroses  of  the  shoulder ;  the  brachial  aponeurosis  ;  the  apo- 
neurosis of  the  forearm ;  the  dorsal  and  anterior  annular  ligaments  of  the  carpus ;  the 
palmar  aponeurosis ;  and,  lastly,  the  sheaths  for  the  tendons  of  the  flexor  muscles  of  the 
fingers. 

The  Aponeuroses  of  the  Shoulder. 

These  are  the  supraspinous,  the  infror spinous,  the  sub-scapular,  and  the  deltoid  aponeu- 
roses. 

The  supraspinous  aponeurosis  is  a  thick  layer  of  fibrous  tissue,  attached  to  the  entire 
circumference  of  the  supra-spinous  fossa,  and  converting  it  into  a  sort  of  osteo-fibrous 
case,  that  serves  as  a  sheath  for  the  supra-spinatus  muscle,  to  which  it  also  affords  sev- 
eral points  of  attachment.  This  tendinous  layer  is  gradually  lost,  externally,  under  the 
acromio-coracoid  arch. 

The  infra-spinous  aponeurosis  is  an  equally  dense  and  strong  fibrous  lamina,  attached 
to  the  entire  margin  of  the  infra-spinous  fossa,  and  completing  the  osteo-fibrous  sheath 
of  the  infra-spinatus  muscle  :  it  is  continuous  on  the  outside  with  the  brachial  fascia,  and 
gives  off  from  its  anterior  surface  a  thick  septum  intervening  between  the  scapular  at- 
tachments of  the  teres  major  and  those  of  the  teres  minor,  and  also  some  thinner  septa 
interposed  between  the  teres  minor  and  the  infra-spinatus,  and  between  the  different 
portions  of  the  infra-spinatus  muscle  itself 

The  deltoid  aponeurosis.  The  infra-spinous  aponeurosis  having  reached  the  posterior 
border  of  the  deltoid  muscle,  splits  into  two  layers  :  of  these,  the  superficial  layer  invests 
the  deltoid,  and  terminates  in  the  brachial  aponeurosis  ;  the  deep  layer  continues  to  cover 
the  tendon  of  the  infra-spinatus,  and  becomes  attached  to  the  tendon  of  the  short  head 
of  the  biceps.  Some  very  loose  cellular  tissue,  or  even  a  synovial  bursa,  separates  this 
aponeurosis  from  the  head  of  the  humerus,  and  the  tendons  inserted  around  it. 

The  subscapular  apo7icurosis  is  a  very  thin  membrane,  which  completes  the  sheath  of 
the  sub-scapularis,  and  gives  the  muscle  some  points  of  attachment.  It  is  fixed  to  the 
entire  margin  of  the  sub-scapular  fossa. 

*  [/.  e.,  the  inner  half  of  the  flexor  brevis  pollicis  of  anatomists  generally.] 
t  [Including  the  outer  portion  of  the  flexor  brevis  pollicis  of  most  anatomists.] 
t  See  note  on  ApoNE urology,  p.  296. 


I 


APONEUROLOGY. 

The  Brachial  Aponeurosis. 

The  brachial  aponeurosis  commences  above  at  the  clavicle,  the  acromion,  and  the  spine 
of  the  scapula,  and  is  continuous  with  the  infra-spinous  aponeurosis  :  on  the  inner  side 
it  arises  from  the  tendons  of  the  pectoralis  major  and  the  latissimus  dorsi ;  and,  in  the 
interval  between  them,  from  the  cellular  tissue  of  the  axilla ;  it  envelops  the  arm  as  far 
down  as  the  elbow,  where  it  becomes  continuous  with  the  fascia  of  the  forearm,  and  is 
attached  to  the  different  bony  projections  presented  by  the  surface  of  that  joint.  Its  su- 
■perficiaJ,  surface  is  separated  from  the  skin  by  vessels  and  nerves,  to  which  it  furnishes 
sheaths  of  greater  or  less  extent.  We  may  admit  the  existence  of  a  superficial  fascia 
between  the  vessels  and  the  skin. 

Its  deep  surface  presents  various  septa,  dividing  its  interior  into  a  certain  number  of  thin 
sheaths  for  the  several  muscles.  It  is  composed  almost  entirely  of  circular  fibres,  some 
of  which  have  a  somewhat  spiral  direction  :  these  fibres  are  intersected  at  right  angles 
by  others  passing  vertically  downward  to  the  fascia  of  the  forearm. 

The  brachial  aponeurosis  is  so  loose  as  to  permit  the  free  exercise  of  the  muscles  con- 
tained within  it,  yet  sufficiently  tense  to  prevent  their  displacement. 

It  is  slightly  thickened  on  either  side,  along  the  outer  and  inner  borders  of  the  humerus, 
and  gives  off  in  those  situations  two  very  strong  inter-muscular  septa  :  one  external,  the 
other  internal.  These  septa  are  in  every  respect  analogous  to  those  of  the  femoral 
fascia,  and  divide  the  brachial  sheath  into  two  great  compartments  :  an  interior,  contain- 
ing the  muscles  on  the  anterior  aspect  of  the  arm,  viz.,  the  biceps,  the  brachialis  anti- 
cus,  and  the  coraco-brachialis,  also  the  upper  or  brachial  portion  of  the  supinator  longus, 
and  the  extensor  carpi  radialis  longior ;  the  posterior  compartment  belongs  to  the  triceps. 

The  external  inter-muscular  septum  arises  from  the  anterior  border  of  the  bicipital 
groove,  by  a  narrow  and  very  thick  extremity,  blended  with  the  posterior  margin  of  the 
tendon  of  the  deltoid  ;  it  reaches  the  outer  border  of  the  humerus,  expands  and  becomes 
somewhat  thinner,  and  separates  the  anterior  from  the  posterior  muscles,  more  espe- 
cially the  triceps  from  the  brachialis  anticus,  affording  attachments  to  them  both.  It  is 
perforated  very  obliquely  by  the  musculo-spiral  or  radial  nerve,  and  the  superior  profunda 
artery,  which  at  first  lie  behind,  but  are  afterward  in  front  of  it.  The  sheath  of  this 
nerve  and  artery  establish  a  free  communication  between  the  anterior  and  posterior  com- 
partments already  alluded  to. 

The  internal  inter-muscular  septum,  broader  and  thicker  than  the  preceding,  but,  like  it, 
of  a  triangular  form,  arises  from  the  posterior  border  of  the  bicipital  groove,  below  the 
teres  major,  is  continuous  with  the  tendon  of  the  coraco-brachialis,  crossing  it  at  a  very 
acute  angle,  and  becoming  partially  united  to  and  blended  with  it,  proceeds  along  and 
adheres  closely  to  the  inner  border  of  the  humerus,  and  terminates  at  the  inner  condyle 
or  epitrochlea  of  that  bone.  Both  of  these  septa  are  formed  by  bands  and  fibres  given 
off  in  succession  from  the  corresponding  borders  of  the  humerus,  and  they  both  afford 
attachments  to  the  brachialis  anticus  in  front,  and  to  the  triceps  behind.  The  ulnar 
nerve  is  anterior  to  the  internal  septum  in  the  upper  part  of  the  arm,  but  perforates  it, 
and  remains  in  contact  with  its  posterior  surface,  passing  between  the  attachments  ot 
the  triceps. 

From  these  two  great  sheaths  the  proper  sheaths  of  the  muscles  proceed.  First,  the 
deltoid  has  its  proper  sheath  :  another  thin  aponeurotic  layer,  gradually  becoming  thicke? 
from  above  downward,  consisting  almost  entirely  of  vertical  fibres,  and  forming  one  of 
the  origins  of  the  aponeurosis  of  the  forearm,  separates  the  biceps  from  the  brachialis 
anticus  ;  again,  the  brachial  vessels  and  the  median  nerve  have  a  special  sheath,  which 
also  receives  at  its  upper  part  the  basilic  vein,  and  the  ulnar  and  internal  cutaneou* 
nerves  ;  this  is  the  brachial  canal,  the  counterpart  of  the  femoral  canal ;  it  establishes  a 
communication  between  the  cellular  tissue  of  the  axilla,  and  that  in  the  bend  of  the 
elbow ;  lastly,  a  tendinous  layer  separates  the  upper  half  of  the  long  head  of  the  triceps 
from  the  other  portions  of  that  muscle  :  the  sheath  of  the  coraco-brachialis  is  given  ofl 
from  the  inner  edge  of  the  biceps. 

We  must  consider  as  dependances  of  the  common  brachial  investment  the  several 
sheaths  furnished  by  it  to  the  cephalic,  basilic,  and  median  veins,  to  the  branches  of  the 
internal  cutaneous  nerve,  and  to  the  superficial  ramifications  of  the  musculo-cutaneous 
nerve.  When  an  artery  or  a  vein  previously  situated  under  an  aponeurosis  becomes 
sub-cutaneous,  the  perforation  in  the  aponeurosis  is  almost  always  of  an  arched  form. 

The  brachial  aponeurosis  has  no  muscle  analogous  to  the  tensor  vaginae  femoris  ;  the 
pectoralis  major  and  the  latissimus  dorsi  are  sufficient  to  effect  its  tension. 

The  Aponeurosis  of  the  Fokeakm  and  Hand. 

The  Aponeurosis  of  the  Forearm. 

Dissection. — ^Make  a  circular  incision  through  the  skin,  immediately  above  the  elbow, 

and  from  this  let  two  vertical  incisions  be  carried  downward  to  the  wrist,  one  in  front 

and  the  other  behind ;  let  the  incisions  extend  through  to  the  fascia,  without  dividing  it  ; 

then  cautiously  remove  the  skin,  being  careful  to  take  Math  it  the  sub-cutaneous  adipose 


THE  APONEUROSIS  OF  THE  FOREARM.  31*3 

tissue ;  the  superficial  veins  and  nerves  may  be  preserved.  The  external  surface  of  the 
fascia  may  be  studied  first,  and  its  several  sheaths  afterward  opened  in  succession. 

The  aponeurosis,  or  fascia  of  the  forearm,  ■^orms  a  general  sheath,  entirely  surrounding 
or  embracing  that  portion  of  the  upper  extremity,  with  the  exception  of  the  posterior 
border  of  the  ulna.  It  is  semi-transparent,  and  hence  can  be  seen  to  be  traversed  by 
white  lines,  generally  vertical  in  their  direction,  which  indicate  a  corresponding  number 
of  thickenings  of  the  sheath,  and  inter-muscular  septa  given  off  from  them. 

It  is  separated  from  the  skin  by  the  superficial  veins  and  nerves  ;  by  its  upper  part  it 
gives  numerous  attachments  to  the  subjacent  muscles,  and  this  renders  the  dissection 
very  difficult.  By  making  a  vertical  incision,  however,  along  the  separate  sheath  which 
it  furnishes  to  each  of  the  muscles,  and  then  carefully  removing  the  latter,  a  good  idea 
may  be  formed  of  the  numerous  angular  compartments  into  which  the  common  cavity 
of  the  fascia  is  subdivided.  In  the  first  place,  it  will  be  seen  that  this  fascia,  like  all 
other  investing  aponeuroses,  is  composed  of  proper  and  superadded  fibres ;  that  the 
proper  fibres  are  nearly  or  quite  circular,  are  more  or  less  oblique,  and  more  or  less  in- 
terlaced, but  the  superadded  fibres  are  vertical.  It  will  be  found  that  it  is  twice  as  thick 
upon  the  dorsal  as  upon  the  palmar  surface  of  the  forearm ;  that  its  thickness  and  its 
strength  increase  from  above  dowTiward  ;  and  that  it  is  strengthened  by  a  great  number 
of  superadded  fasciculi,  consisting  of  aponeurotic  expansions  from  the  tendons  of  the 
adjacent  muscles.  Thus,  the  brachialis  anticus  on  the  outside,  the  biceps  on  the  inside 
and  in  front,  and  the  triceps  behind,  give  off  tendinous  expansions  to  this  aponeurosis  : 
of  these  the  most  remarkable  is,  without  doubt,  that  given  off  from  the  biceps,  which 
muscle  may  be  regarded,  indeed,  as  the  tensor  of  the  anterior  portion  of  the  fascia. 
This  expansion  constitutes,  in  fact,  one  of  the  terminations  of  the  biceps,  with  the  ex- 
ternal fasciculi  of  which  it  is  continuous,  and,  moreover,  arises  from  the  outer  edge  and 
the  anterior  surface  of  its  tendon.  This  expansion,  so  important  in  consequence  of  its 
relations  with  the  brachial  artery,  passes  obliquely  inward  and  downward,  and,  as  it  ex- 
pands, intersects  at  right  angles  the  vertical  fasciculi  proceeding  from  the  epithrochlea 
and  epicondyle  of  the  humerus.  These  last-mentioned  fasciculi  also  appear  to  me  to  be 
supplementary ;  they  are  continuous  with  the  common  tendons  of  origin  of  the  external 
and  internal  muscles  of  the  forearm,  and  constitute  the  anterior  walls  of  those  two  mul- 
tilocular  pyramids,  of  which  one  is  on  the  inner,  the  other  on  the  outer  side  of  the  fore- 
arm, or  of  that  series  of  trumpet-shaped  cavities  (cornets),  as  M.  Gerdy  calls  them,  from 
each  of  which  the  muscles  of  these  regions  take  their  origin.  I  must  not  omit  to  men- 
tion the  thick  tendinous  band,  which  arises  from  the  entire  length  of  the  posterior  border 
of  the  ulna,  divides  into  two  layers  to  give  origin  to  the  flexor  carpi  ulnaris,  and  by  its 
internal  or  deep  surface  affords  attachment  to  the  flexor  sublimis. 

In  the  fascia  of  the  forearm  there  are  numerous  foramina  for  the  passage  of  vessels 
and  nerves,  but  I  shall  direct  attention  to  one  very  large  orifice  existing  in  front,  at  the 
bend  of  the  elbow,  and  bounded  on  the  inside  by  the  outer  margin  of  the  tendinous  ex- 
pansion of  the  biceps.  This  opening  establishes  a  free  communication  between  the  sub- 
cutaneous and  the  sub-aponeurotic  cellular  tissue  at  the  bend  of  the  elbow,  and  leads 
into  a  sort  of  fossa,  in  which  are  found  the  tendon  of  the  biceps,  the  brachial  artery,  the 
commencement  of  the  radial  artery,  and  the  median  nerve.  This  fossa  is  lined  by  apo- 
neurotic laminae  :  on  the  outside,  by  the  layer  which  covers  the  inner  surface  of  the  supi- 
nator longus,  the  radial  extensors,  and  the  flexor  sublimis  ;  on  the  inside,  by  the  layer 
which  completes  the  sheath  of  the  pronator  teres  :  it  communicates  above  with  the  canal 
of  the  brachial  artery,  and  below  with  the  canals  through  which  the  radial,  ulnar,  and 
interosseous  arteries  and  the  median  nerve  proceed  downward  to  the  forearm. 

From  the  internal  surface  of  this  fascia  a  number  of  laminaj  are  given  off,  to  form  the 
following  muscular  sheaths : 

In  the  anterior  region  of  the  forearm,  a  transverse  septum,  thicker  below  than  above, 
divides  the  superficial  layer  of  muscles  from  the  middle  layer,  consisting  of  the  flexor 
sublimis,  and  also  from  the  deep  layer,  composed  of  the  flexor  profundus  digitorum  and 
the  flexor  longus  pollicis.  Other  septa,  passing  from  before  backward,  divide  the  mus- 
cles of  the  superficial  layer  from  each  other.  Lower  down  the  sheaths  of  the  flexor  carpi 
radialis  and  palmaris  longus,  which  are  perfectly  distinct  from  each  other,  are  situated 
in  front  of  the  remainder  of  the  fascia ;  and  this  has  led  to  the  statement  of  some  anat- 
omists, that  the  fascia  is  perforated  by  the  tendons  of  these  muscles,  especially  by  that 
of  the  palmaris  longus.  The  radial  artery  has  a  special  sheath  throughout  its  whole  ex- 
tent ;  the  ulnar  artery  and  nerve  have  a  proper  sheath  only  in  the  lower  part  of  the  forearm. 

In  the  posterior  region  of  the  forearm,  the  fascia  is  much  stronger  than  in  the  anterior. 
A  transverse  layer  separates  the  muscles  of  the  superficial  from  those  of  the  deep  layer; 
and  septa,  passing  from  behind  forward,  subdivide  these  common  sheaths  into  several 
smaller  ones,  corresponding  in  number  to  that  of  the  muscles.  Thus,  we  find  a  sheath 
for  the  extensor  communis  digitorum,  a  second  for  the  extensor  digiti  minimi,  a  third 
for  the  extensor  carpi  ulnaris,  and  a  fourth  for  the  anconeus.  The  supinator  longus  and 
the  two  radial  extensors  of  the  wrist  appear  to  be  in  the  same  sheath  ;  but  a  more  or 
less  distinct  membrane  surrounds  the  first  of  these  muscles :  the  supinator  brevis  has 


318  APONEUROLOGY. 

also  a  proper  sheath.  We  find  a  common  sheath  for  the  extensor  longus  poUicis  and  the 
extensor  proprius  indicis.  The  abductor  longus  and  the  extensor  brevis  poUicis,  which, 
properly  speaking,  constitute  but  one  muscle,  have  also  a  common  sheath  accompanying 
them  as  far  as  the  dorsal  annular  ligament  of  the  wrist. 

The  Dorsal  Annular  Ligament  of  the  Wrist,  and  the  Dorsal  Aponeurosis  of 

the  Metacarpus. 

The  dorsal  annular  ligament  of  the  wrist  (r,  Jig.  121)  may  be  considered  as  a  depend- 
ence of  the  fascia  of  the  forearm,  which  in  this  situation  is  strengthened  by  a  great 
number  of  fibres.  It  is  a  band  of  six  or  eight  lines  in  width,  passing  obhquely  inward 
and  downward  over  the  extensor  tendons  of  the  hand,  perforated  by  a  number  of  open- 
ings for  the  passage  of  vessels,  and  distinguishable  from  the  fascia  of  the  forearm 
only  by  its  somewhat  greater  thickness  and  by  the  parallel  arrangement  of  its  fascicuU. 
It  arises  internally  from  the  pisiform  bone  and  the  palmar  fascia,  passes  first  over  the 
ulnar  side,  and  then  the  posterior  surface  of  the  carpus,  is  interrupted  by  the  outer  mar- 
gin of  the  groove  for  the  two  radi2d  extensor  muscles,  takes  a  fresh  origin  from  that  mar- 
gin, covers  the  radial  side  of  the  wrist,  and  is  inserted  partly  into  the  radius,  and  partly 
into  the  fascia  of  the  forearm.  From  the  anterior  surface  of  this  thick  fibrous  band 
arise  several  small  prolongations,  which  are  interposed  between  the  numerous  tendons 
passing  over  the  dorsal  and  radial  aspects  of  the  carpus,  and  convert  the  grooves  upon 
the  lower  extremities  of  the  radius  and  ulna  into  canals.  Thus,  proceeding  from  with- 
out inward,  and  from  before  backward,  we  find,  1 .  A  sheath  for  the  united  tendons  of  the 
abductor  longus  and  extensor  brevis  pollicis ;  2  and  3.  Two  distinct  sheaths  opposite 
the  radius  :  one  for  the  two  radial  extensors  of  the  carpus,  the  other  for  the  extensor 
longus  pollicis,  which  sheaths  become  blended  together  lower  down  into  a  single  com- 
pletely fibrous  sheath  ;  4.  A  fourth  sheath,  stronger  than  the  preceding,  for  the  extensor 
communis  digitorum  and  the  extensor  proprius  indicis  ;  5.  An  entirely  fibrous  sheath  for 
the  extensor  digiti  minimi ;  6.  A  very  strong  sheath  for  the  extensor  carpi  ulnaris, 
which  is  prolonged  below  the  ulna,  and  accompanies  the  tendon  as  far  as  the  fifth  meta- 
carpal bone.  All  these  sheaths  are  lined  by  synovial  membranes,*  which  extend  some 
distance  above  the  dorsal  annular  ligament,  and,  on  the  other  hand,  accompany  the  ten- 
dons very  far  down,  sometimes  even  to  their  insertions. 

The  dorsal  aponeurosis  of  the  metacarpus  is  a  continuation  of  the  dorsal  annular  liga- 
ment :  it  is  composed  of  a  very  thin  layer  of  transverse  fibres,  and  separates  the  exten- 
sor tendons  from  the  sub-cutaneous  vessels  and  nerves.  A  very  loose,  extensible,  and 
elastic  cellular  tissue  takes  the  place  of  the  synovial  membranes  over  these  tendons,  and 
greatly  facilitates  their  movements. 

The  Anterior  Annular  Ligament  of  the  Carpus. 

The  deep  groove  upon  the  anterior  surface  of  the  carpus  is  converted  into  a  canal  by 
a  very  thick  fibrous  band,  viz.,  the  anterior  ligament  of  the  carpus  {g,fig.  118).  It  com- 
mences internally  by  two  well-marked  origins,  separated  from  each  other  by  the  ulnar 
nerve,  one  being  from  the  pisiform  bone  and  the  tendon  of  the  flexor  carpi  ulnaris,  the 
other  from  the  unciform  bone.  The  first  bundle  passes  downward,  the  second  trans- 
versely, and  their  united  fibres,  some  of  which  are  transverse  and  others  interlaced,  ter- 
minate at  the  trapezium  and  the  scaphoid,  giving  off  an  expansion  to  the  fascia  cover- 
ing the  ball  of  the  thumb,  with  which  they  are  continuous.  This  ligament  is  continuous 
above  with  the  fascia  of  the  forearm,  which  is  much  thickened  in  this  situation :  it  re- 
ceives in  front  the  expanded  tendon  of  the  palmaris  longus,  and  terminates  below  in  the 
palmar  fascia.  Its  anterior  surface  gives  attachment  to  most  of  the  muscles  of  the  the- 
nar and  hypothenar  eminences.  A  small  portion  only  of  this  ligament  is  generally  seen 
and  described,  viz.,  the  free  portion.  If  it  is  wished  to  obtain  a  perfect  conception  of  it, 
the  muscles  attached  to  its  anterior  surface  should  be  carefully  removed ;  it  will  then  be 
seen  that,  on  the  outside,  it  describes  a  curve  having  its  concavity,  directed  inward,  in 
order  to  be  attached  to  the  scaphoid  and  the  trapezium,  and  that  the  sheath  of  the  flexor 
carpi  radiahs  is  contained  in  its  substance :  this  sheath  is  entirely  fibrous  above,  and 
partly  fibrous  and  partly  osseous  below,  where  it  converts  into  a  canal  the  groove  on  the 
trapezium. 

While  there  are  almost  as  many  synovial  membranes  as  there  are  sheaths  under  the 
dorsal  ligaments  of  the  carpus,  on  the  palmar  aspect  nine  tendons  with  the  median  nerve 
form  but  a  single  bundle,  which  is  lubricated  by  one  or  two  synovial  membranes.  This 
synovial  membrane*  presents  a  curious  arrangement,  subject,  moreover,  to  numerous 
varieties.  It  lines  the  posterior  surface  of  the  anterior  annular  ligament  of  the  carpus 
is  prolonged  above  and  below  that  ligament,  and  is  reflected  (without  passing  between 
the  different  tendons)  upon  the  anterior  surface  of  the  bundle  formed  by  them  and  by  the 
median  nerve,  which  is  to  their  outer  side.  In  order  to  obtain  an  accurate  idea  of  the 
termination  of  this  synovial  membrane,  cut  across  the  tendons  at  the  lower  part  of  the 
forearm,  and  turn  them  forward  upon  the  palm  of  the  hand :  it  will  then  be  seen  that  the 

*  See  note,  p.  296. 


THE    PALMAR    APONEUROSIS,    ETC.  319 

synovial  membrane  is  reflected  upon  the  ulnar  border  of  the  bundle  of  tendons  ;  that  it 
lines  the  posterior  surface  of  this  bundle,  passing  more  or  less  between  the  tendons,  and 
separating  them  from  each  other  in  a  rather  irregular  manner  ;  that  it  is  reflected  upon 
the  groove  of  the  carpus,  prolonged  upward  and  downward  much  farther  than  it  was  in 
front,  and  divided  below  into  four  small  prolongations  corresponding  to  the  flexor  ten- 
dons of  each  finger.  Nor  is  this  all,  for  there  is  a  special  synovial  membrane  for  the 
flexor  longus  poUicis.  In  order  to  expose  this,  the  synovial  membrane  must  be  cut 
through  where  it  is  reflected,  on  its  radial  side,  from  the  annular  ligament  on  to  the  me- 
dian nerve  and  the  anterior  surface  of  the  bundle  of  tendons  :  a  special  and  very  exten- 
sive synovial  membrane  will  then  be  seen  to  pass  high  up  along  the  tendon  of  the  flexor 
longus  pollicis,  and  to  be  prolonged  downward  as  far  as  the  last  phalanx  of  the  thumb. 

The  Palmar  Aponeurosis. 

The  palmar  fascia  (,c,fig.  118)  forms  a  common  sheath  for  all  the  muscles  of  the  palm 
of  the  hand,  and  is  divided  into  three  portions,  a  middle  and  two  lateral. 

The  middle  portion.  This  is  the  only  part  generally  described  as  the  palmar  fascia ; 
it  is  triangular  and  strong,  but  of  variable  thickness  :  it  binds  down  the  numerous  sub- 
jacent tendons.  It  arises  from  the  anterior  surface  and  lower  margin  of  the  anterior 
annular  Ugament  of  the  carpus,  and  from  the  tendon  of  the  palmaris  longus,  which  may 
be  regarded  as  its  tensor  muscle.  Between  these  two  origins  the  ulnar  artery  pene- 
trates into  the  palm  of  the  hand.  Not  unfrequently  the  expanded  tendon  of  the  palma- 
ris longus  forms  a  fibrous  layer  in  front  of  the  proper  palmar  fascia.  This  fascia  is  nar- 
row and  thick  at  its  origin,  but  expands  as  it  proceeds  from  above  downward,  and,  op- 
posite the  heads  of  the  metacarpal  bones,  divides  into  eight  prolongations  for  the  four 
inner  fingers.  At  the  seat  of  this  division  we  find  very  strong  transverse  fibres  binding 
the  prolongations  together,  and  preventing  disjunction  of  the  fingers  and  laceration  of 
the  fascia.  By  this  arrangement  four  arches  are  formed,  under  which  the  tendons  of 
the  flexor  muscles  pass  :  between  these  four  arches  there  are  three  smaller  ones,  giving 
passage  to  the  collater£il  vessels  and  nerves  of  the  fingers,  and  to  the  lumbricales,  so  that  al- 
together there  are  seven  arches.  These  arches  are  true  fibrous  canals.  In  order  perfect- 
ly to  understand  their  structure,  make  a  vertical  incision  through  the  palmar  fascia  ;  it  will 
then  be  seen  that,  opposite  the  arches,  tendinous  prolongations  or  tongues  are  detached 
from  the  deep  surface  of  the  fascia  :  these  prolongations  turn  round  the  sides  of  the  ten- 
dons so  as  to  embrace  them,  and  become  continuous  with  the  anterior  or  glenoid  liga- 
ment of  the  metacarpo-phalangal  articulations  :  the  same  arrangement  obtains  with  re- 
gard to  the  three  small  arches  for  the  vessels  and  nerves  situated  between  the  four  prin- 
cipal tendinous  arches.  The  palmar  fascia  is,  moreover,  intimately  united  to  the  skin 
by  very  numerous  prolongations  :  its  deep  surface  covers  the  superficial  palmar  arch  of 
the  arteries  of  the  hand,  the  median  and  ulnar  nerves,  and  the  flexor  tendons  ;  a  very 
loose  and  extensible  cellular  tissue  separates  it  from  these  parts,  and  facilitates  the  move- 
ments of  the  tendons.  From  its  inner  margin  is  given  off  a  very  strong  layer,  which 
becomes  continuous  with  the  interosseous  aponeurosis,  and  separates  the  middle  from 
the  internal  palmar  region  ;  a  thinner  layer  proceeds  from  its  outer  margin,  and  passes 
down  between  the  muscles  of  the  thenar  eminence  and  the  first  lumbricalis  muscle. 
This  small  muscle,  called  the  palmaris  brevis  (Jb,fig.  118),  arises  from  the  inner  margin  of 
the  middle  palmar  fascia,  and  is  merely  a  cutaneous  muscle. 

The  external  and  internal  palmar  fascia,  or  the  thenar  and  hypothenar  aponeuroses. 
These  consist  of  two  rather  thin  fibrous  layers,  forming  the  sheaths  of  the  muscles  of 
the  ball  of  the  thumb  and  those  of  the  little  finger  :  they  are  both  continuous  with  the 
middle  palmar  fascia :  the  external  appears  to  consist,  in  a  great  measure,  of  an  expan- 
sion from  the  tendon  of  the  abductor  longus  pollicis  ;  and  the  internal,  of  an  expansion 
from  that  of  the  flexor  carpi  ulnaris.  At  the  limits  between  these  aponeuroses  and  the 
middle  fascia  are  formed  two  septa,  passing  from  before  backward,  and  dividing  the  palm 
of  the  hand  into  three  distinct  sheaths  :  one  median,  completed  by  the  interosseous  apo- 
neurosis, and  intended  for  all  the  flexor  tendons  and  the  principal  vessels  and  nerves  of 
the  hand ;  the  other  two  placed  on  either  side,  and  binding  down  the  muscles  of  the  the 
nar  and  hypothenar  eminences. 

The  Sheaths  of  the  Flexor  Tendons  of  the  Fingers,  and  their  Synovial  Mem- 
branes. 
After  leaving  the  arches,  or,  rather,  the  curious  sheaths,  formed  by  the  palmar  fascia 
immediately  above  the  corresponding  metacarpo-phalangal  articulation,  each  pair  of  flex 
or  tendons  is  received  into  a  special  sheath,  by  which  they  are  accompanied  down  to 
the  last  phalanx.  It  will  be  remembered  that  the  anterior  surfaces  of  the  first  and  sec- 
ond phalanges  are  marked  by  a  longitudinal  groove  ;  to  the  two  borders  of  this  groove  is 
attached  a  very  regular  semi-canal  of  fibrous  tissue,  which  is  exactly  large  enough  to 
contain  the  two  flexor  tendons.  This  very  strong  sheath  preserves  its  shape  when  the 
tendons  have  been  removed  ;  and  a  correct  idea  of  its  importance  may  be  obtained  by 
observing  the  effects  of  contraction  of  the  flexor  muscles  after  it  has  been  divided.    This 


320  SPLANCHNOLOGY. 

sheath  is  formed  of  parallel  semicircular  laminae,  placed  one  above  the  other,  densely  ag- 
gregated over  the  bodies  of  the  phalanges,  and,  for  the  most  part,  forming  a  continuous 
sheath,  but  becoming  more  and  more  separated,  and  sometimes  even  completely  disap- 
pearing opposite  the  articulations  and  the  articulating  extremities  of  the  bones.  It  ap- 
pears to  me  that,  in  the  movements  of  flexion,  these  articular  rings  are  pushed  into  each 
other.  The  sheath  ceases  altogether  above  the  articulation  of  the  second  with  the  ter- 
minal phalanx. 

A  very  remarkable  synovial  membrane,*  which  is  prolonged  upward  beyond  the  arch- 
es formed  by  the  palmar  fascia,  lines  the  whole  lenth  of  each  osteo-fibrous  sheath  on  the 
one  hand,  and  on  the  other  is  reflected  upon  the  two  flexor  tendons,  affording  each  of  them 
a  sheath,  and  forms  two,  often  three  or  four  triangular  folds,  having  their  bases  directed 
upward,  and  being  perfectly  analogous  to  the  so-called  adipose  ligament  of  the  knee- 
joint.  Of  these  folds,  the  superior  is  situated  opposite  the  upper  extremity  of  the  first 
phalanx,  and  extends  from  the  tendon  of  the  flexor  sublimus  to  that  of  the  flexor  pro- 
fundus ;  the  inferior  fold  passes  from  the  bifurcation  of  the  superficial  tendon  to  the  deep 
tendon ;  the  others  are  intermediate,  and  proceed  from  the  phalanx  to  the  two  tendons. 
These  synovial  folds  can  be  very  well  seen  by  raising  and  separating  the  flexor  tendons 
from  the  phalanges.  Not  unfrequently  the  synovial  membrane  forms  a  hernia  between 
two  of  these  tendinous  rings,  either  opposite  the  body  of  a  phalanx,  or,  still  more  com- 
monly, over  one  of  the  articulations.  We  may  add,  that  these  synovial  folds  are  proba- 
bly intended  to  support  the  nutritious  vessels  of  the  tendons,  and  not  to  connect  these 
tendons  together. 


SPLANCHNOLOGY. 

General  Observations  on  the  Viscera. — External  Conformation. — Structure. — Development. 
— Functions. — Dissection. 

Splanchnology  (from  crcTMyxvov,  viscus)  is  that  division  of  anatomy  which  treats  of 
organs  more  or  less  compound  in  their  structure.  Some  of  these  are  contained  within 
the  three  great  visceral  cavities  (_the  viscera),  while  others  are  situated  without  these 
cavities  {organs,  properly  so  called),  t 

The  brain,  the  spinal  cord,  the  heart,  and  the  organs  of  the  senses,  are  generally  in- 
cluded in  this  division.  I  have  thought  it  advisable,  however,  to  confine  myself  here  to 
the  description  of  the  digestive,  respiratory,  and  genito-urinary  apparatus.  The  organs 
of  the  senses,  the  brain,  and  the  spinal  cord  will  be  studied  more  advantageously  in  con- 
nexion with  the  rest  of  the  nervous  system,  and  the  heart  with  the  other  organs  of  the 
circulation. 

As  the  organs  we  are  about  to  examine  have  few  relations  with  each  other,  they  do 
not  admit  of  such  extended  and  important  general  remarks  as  those  which  preceded  the 
osteological  and  myological  divisions.  I  shall  content  myself  with  explaining  briefly  the 
method  in  which  the  description  of  each  organ  should  be  pursued. 

Every  organ  presents  for  consideration  its  external  conformation,  its  internal  confor- 
mation or  its  structure,  its  development,  and  its  functions. 

The  External  Conformation  of  Organs. 

The  description  of  the  external  conformation  of  organs  includes  that  of  their  nomen- 
clature, number,  situation,  direction,  size,  shape,  and  relations. 

Nomenclature. — The  nomenclature  of  organs  has  not  been  subjected  to  so  many  chan- 
ges as  that  of  the  bones  and  muscles :  the  names  adopted  by  the  oldest  authors  have 
been  retained  in  modern  science,  and  are  even  used  in  common  language. 

The  names  of  organs  are  derived,  1.  From  their  uses,  as  the  asophagus  (from  olu,  I 
convey,  and  (^ayo),  I  eat) ;  also,  the  lachrymal  and  the  salivary  glands.  2.  From  their 
length,  as  the  duodenum.  3.  From  their  direction,  as  the  rectum.  4.  From  their  shape, 
as  the  amygdala  (the  tonsils).  5.  From  their  structure,  as  the  ovaries.  6.  From  the 
name  of  the  authors  who  have  best  described  them,  as  the  Schneiderian  membrane,  the 
FaUopian  tubes.  Lastly,  they  are  conventional  words  ;  for  example,the  tongue,  the  liver,  &c. 

Number. — Some  organs  are  single  ;  others  exist  in  pairs.  Varieties  in  number  are 
very  common,  both  by  excess  and  by  defect.  Thus,  three  kidneys  have  been  found  in 
the  same  individual,  and  there  is  often  only  one.  Examples  have  been  recorded  of  in- 
dividuals having  three  testicles  ;  one  is  uncommon.  Lastly,  varieties  by  excess  almost 
always  result  from  the  division,  and  those  by  defect,  from  the  union  or  fusion  of  organs. 

Situation. — This  must  be  considered  with  regard  to  the  region  of  the  body  occupied  by 
an  organ,  i.  e.,  its  general  or  absolute  situation;  and  also  with  regard  to  its  relations  with 
neighbouring  organs,  i.  e.,  its  relative  situation.     Thus,  when  it  is  stated  that  the  stom- 

*  See  note,  p.  298. 

t  All  the  viscera  are  organs,  but  all  the  organs  are  not  viscera.  The  word  viscus  is  probably  derived  from 
veacor,  I  eat,  because  a  great  number  of  the  viscera  are  eng:aged  in  the  functions  of  nutritioi . 


STRUCTURE   AND   DEVELOPMENT    OF    ORGANS.  321 

ach  occupies  the  left  hypochondrium  and  the  epigastrium,  its  absolute  or  general  situa- 
tion is  indicated  ;  but  when  it  is  added  that  this  viscus  is  situated  between  the  oesopha- 
gus and  duodenum,  below  the  diaphragm,  and  above  the  transverse  mesocolon,  its  relative 
situation  is  implied. 

Many  of  the  organs  are  subject  to  varieties  of  position ;  and  this  constitutes  an  im- 
portant point  in  their  history.  These  varieties  of  position  depend  upon  congenital  oi 
upon  accidental  displacement,  either  affecting  the  particular  organ  only,  or  consequent 
upon  displacement  of  the  neighbouring  organs  ;  or  they  may  result  from  a  change  in  the 
size  of  the  organ  itself 

Size. — The  absolute  size  of  an  organ  is  determined  by  linear  measurements,  by  the 
quantity  of  water  which  it  displaces,  and  by  its  weight ;  its  relative  size,  by  comparison 
with  bodies  of  a  known  size,  or  with  other  organs. 

The  size  of  organs  is  subject  to  a  great  number  of  varieties.  These  depend  either  on 
age,  as  in  the  liver,  testicles,  and  thymus  gland ;  on  sex,  temperament,  or  on  individual 
peculiarities  ;  also  on  the  state  in  which  an  organ  is  found  :  for  example,  the  uterus,  pe- 
nis, and  spleen.  Lastly,  there  are  some  pathological  variations,  which  shoxild  not  be 
omitted  in  a  treatise  upon  descriptive  anatomy. 

Figure. — The  figure  of  the  organs  treated  of  in  splanchnology  appears  to  follow  these 
rules.  The  double  organs  do  not  exactly  resemble  each  other  on  the  right  and  left  sides 
of  the  body.  The  single  organs,  occupying  the  median  line,  are  symmetrical ;  but  most 
of  those  which  are  removed  from  that  line  are  not  symmetrical.  Nevertheless,  symme- 
try is  not  so  completely  wanting  in  the  viscera  belonging  to  nutritive  life,  as  stated  by  Bi- 
chat,  for  the  stomach  and  the  small  and  great  intestines  may  be  divided  into  two  equal 
halves. 

In  regard  to  their  forms,  organs  are  compared,  in  general,  either  with  familiar  objects, 
or  with  geometric  figures.  Thus,  a  kidney  is  said  to  resemble  a  kidney-bean,  and  either 
lung,  a  cone.  In  very  irregular  organs,  we  merely  describe  the  surfaces  and  the  borders. 
We  shall  not  find  in  the  viscera  the  same  constancy  of  form  as  exists  in  the  organs  of 
relation. 

Direction. — The  direction  of  an  organ  is  determined  in  the  same  manner  as  that  of  the 
bones  and  muscles,  viz.,  by  its  relations  with  the  imaginary  planes  surrounding  the  body, 
or  with  the  mesial  plane. 

Relations. — The  figure  of  an  organ  being  determined,  its  surface  is  then  divided  into 
regions,  the  relations  of  which  are  accurately  ascertained.  These  regions  are  generally 
termed  surfaces  and  borders.  As  the  situation  of  many  organs  is  subject  to  great  varie- 
ties, their  relations  must  also  vary.  Too  much  cannot  be  said  of  the  value  of  an  accu- 
rate knowledge  of  these  relations,  from  which  a  number  of  the  most  important  practical 
inferences  may  be  derived. 

The  Internal  Conformation  &r  Structure  of  Organs. 

The  surface  of  an  organ  being  well  understood,  we  next  proceed  to  the  study  of  its 
structure,  comprising  its  colour,  its  consistence,  and  its  anatomical  elements. 

Colour. — The  colour  both  of  the  surface  and  the  substance  of  an  organ  requires  to  be 
studied.  All  variations  of  colour  should  be  very  carefully  noted.  Age  and  disease  have 
much  influence  over  it ;  and  it  is  often  difficult  to  distinguish  positively  between  its 
physiological  and  pathological  condition. 

Consistence. — The  consistence,  density,  and  fragility  of  organs  are  connected  with  their 
structure.  The  specific  gravity  or  density  of  a  single  organ  only,  the  lung,  has  been  ac- 
curately studied,  and  that  in  a  medico-legal  pomt  of  view.  In  estimating  the  con^^isience 
and  fragility  of  organs,  we  can  only  approximate  the  truth.  It  is  desirable  that  some  more 
methodical  and  accurate  means  should  be  devised  for  the  estimation  of  these  qualities. 

Anatomical  Elements. — The  determination  of  the  immediate  anatomical  elements,  or 
tissues,  which  enter  into  the  composition  of  an  organ,  together  with  their  proportions 
and  their  arrangement,  constitutes  the  knowledge  of  its  structure.  Every  organ  has 
either  a  cellular,  fibrous,  cartilaginous,  or  bony  framework.  Some  organs  are  provided 
with  muscular  fibres,  or  even  with  distinct  muscles  ;  they  all  contain  the  several  kinds 
of  vessels,  viz.,  arteries,  veins,  and  lymphatics ;  and  they  edl  possess  nerves.  The  glan- 
dular organs  have  excretory  ducts. 

In  explaining  the  structure  of  organs,  we  shall,  generally,  confine  ourselves  to  a  brief 
enumemtion  of  their  constituent  parts,  referring  to  works  on  the  anatomy  of  textures  for 
details  which  would  be  misplaced  in  an  elementary  treatise. 

Tkt  Devdopment  of  Organs. 

The  study  of  the  development  of  organs,  and  the  changes  which  they  undergo  at  the 
different  periods  of  intra-  and  extra-uterine  life,  is  of  the  greatest  interest,  at  least  as  re- 
gards some  among  them.  The  formation  of  the  soft  parts,  however,  is  not  nearly  so  weL 
understood  as  that  of  the  hard  tissues,  because  the  most  important  phenomena  of  devel- 
opment occur  during  the  first  weeks  after  conception.  The  remarks  upon  this  subject 
will,  therefore,  generally  point  out  some  hiatus  to  be  filled  up. 

Ss 


822  SPLANCHNOLOGY. 

The  Functions  of  Organs. 
The  functions  or  uses  of  organs  flow  so  naturally  from  their  anatomical  description, 
that  we  shall  follow  the  example  of  the  greater  number  of  anatomists,  in  adding  to  such 
description  a  short  account  of  the  functions  of  an  organ.  We  shall  only  notice  particu- 
larly those  uses  of  organs  which  depend  immediately  upon  their  structure,  referring  to 
physiological  works  for  the  details  and  discussions  of  yet  disputed  points  in  the  science 
of  functions.  No  part  of  anatomy  excites  so  much  curiosity  and  interest  as  splanchnol- 
ogy, in  consequence  of  the  importance  of  the  organs  of  which  it  treats.  Without  a 
knowledge  of  this  department  of  anatomy,  it  is  impossible  to  understand  the  mechanism 
of  functions  the  most  indispensable  to  life  ;  and  as  the  organs  themselves  are  the  seat 
of  the  greater  part  of  the  lesions  which  are  assigned  to  the  physician,  as  well  as  of  many 
of  those  which  fall  under  the  care  of  the  surgeon,  most  of  the  fundamental  questions  of 
the  heeding  art  require  a  profound  knowledge  of  these  organs. 

The  Dissection  of  the  Viscera. 

The  dissection  of  organs  does  not  consist  in  merely  isolating  them  from  surrounding 
parts,  which,  as  far  as  regards  those  contained  in  the  visceral  cavities,  is  done  by  sim- 
ply laying  open  the  latter,  but  in  the  separation  of  their  anatomical  elements  or  tissues. 
For  this  purpose,  injections  of  the  most  delicate  kind,  maceration,  boiling,  preservation 
in  alcohol,  desiccation,  the  action  of  acids,  in  short,  aS\.  the  resources  of  his  art,  are  em- 
ployed by  the  anatomist. 

Having  made  these  preliminary  observations,  we  shall  now  describe  in  succession  the 
organs  of  digestion,  the  organs  of  respiration,  and  the  genito-urinary  apparatus. 


THE  ORGANS  OF  DIGESTION  AND  THEIR  APPENDAGES, 

ALIMENTARY  OR  DIGESTIVE  CANAL. 
General  Observations. — Division. — Mouth  and  its  Appendages. — Lips. — Cheeks. — Hard  and 
Soft  Palate. — Tonsils. — Tongue. — Salivary  Glands. — Buccal  Mucous  Membrane. — Pha- 
rynx.— (Esophagus. — Stomach. — Small  Intestine. — Large  Intestine. — Muscles  of  the  Pe- 
rineum.— Development  of  the  Intestinal  Canal. 

The  organs  of  digestion  form  a  long  canal,  the  alimentary  or  digestive  canal,  extending 
from  the  mouth  to  the  anus,  which  receives  alimentary  substances,  induces  in  them  a 
series  of  changes,  by  which  they  are  rendered  fit  to  repair  the  losses  incurred  by  the 
body,  and,  moreover,  presents  a  vast  absorbent  surface  for  the  action  of  the  lacteal  ves- 
sels.    The  entire  series  of  these  organs  constitutes  the  digestive  apparatus. 

Tlie  existence  of  an  alimentary  canal  is  one  of  the  essential  characters  of  an  animal. 
In  consequence  of  possessing  it,  animals  may  be  detached  from  the  soil,  so  as  to  move 
from  place  to  place.  In  the  lowest  species,  the  entire  animal  is  nothing  more  than  an 
alimentary  sac,  having  a  single  opening,  and  formed  by  a  reflection  of  the  skin  ;  so  that, 
according  to  the  beautiful  observation  of  Trembley,  when  polypes  are  turned  inside  out, 
the  digestive  process  is  performed  as  well  by  their  external  as  by  their  internal  surface. 
Ascending  in  the  scale  of  animals,  the  canal  soon  presents  two  openings,  acquires  larger 
dimensions,  becomes  more  or  less  convoluted,  and  is  distinct  from  other  systems  of  or- 
gans. A  skeleton  clothed  by  muscles  is  interposed  between  it  and  the  skin.  It  becomes 
more  and  more  voluminous,  in  proportion  as  the  nutritive  materials  and  the  textures  of 
the  body  differ  more  widely  in  their  chemical  composition.  What  a  difference  there  is, 
in  this  respect,  between  certain  fishes,  in  which  the  alimentary  canal  is  not  nearly  so 
long  as  the  animal,  and  some  herbivora ;  the  ram,  for  example,  in  which  it  is  twenty- 
seven  times  the  length  of  the  body.  Carnivorous  animals,  again,  have  a  short  and  nar- 
row alimentary  canal.  Man,  being  destined  to  live  both  upon  animal  and  vegetable  sub- 
stances, occupies,  as  it  were,  a  middle  station  between  the  herbivora  and  carnivora. 

General  Situation. — The  digestive  canal  is  situated  in  front  of  the  vertebral  column, 
with  the  direction  of  which  the  straight  portion  of  the  canal  accurately  corresponds, 
while  its  tortuous  part  is  distant  from,  though  invariably  connected  with  it  by  means  of 
membranous  attachments.  It  commences  at  the  lower  part  of  the  face,  traverses  the 
neck  and  the  thorax,  penetrates  into  the  abdominal  cavity,  which  is  almost  exclusively 
intended  for  it,  and  the  dimensions  and  mechanism  of  which  bear  strict  relation  to  the 
functions  of  the  alimentary  canal ;  and  it  terminates  at  the  outlet  of  the  pelvis,  anterior 
to  the  coccyx,  by  the  anal  orifice.  Its  upper  part  is  in  immediate  relation  with  the  or 
gans  of  respiration  ;  its  lower,  with  the  genito-urinary  apparatus. 

Dimensions. — The  length  of  the  digestive  canal  has  been  calculated  to  be  seven  oi 
eight  times  that  of  the  body  of  the  individual.  Its  diameter  is  not  equal  through  its 
whole  extent ;  and  its  alternate  expansions  and  contractions  establish  very  distinct  lim- 
its between  its  several  portions.  The  largest  portion  is,  undoubtedly,  that  which  re- 
ceives the  name  of  the  stomach ;  the  narrowest  parts  are  the  cervical  portion  of  the 
oesophagus,  the  pyloric  opening  of  the  stomac-h,  and  the  ileo-caecal  orifice.     It  is  impor- 


GENERAL   REMARKS. 

tant  to  remark,  that  the  transverse  dimensions  of  an  alimentary  canal  have,  to  a  certain 
extent,  an  inverse  ratio  to  its  length.  Thus,  a  very  wide  intestinal  canal  is  generally 
less  remarkable  for  length.  This  remark  is  illustrated  by  comparative  anatomy  in  the 
fact  that,  in  the  horse,  an  herbivorous  animal,  the  intestinal  canal  is  shorter,  but,  at  the 
same  time,  of  a  much  greater  calibre  than  in  the  ruminantia,  which  are  also  herbivorous. 

Direction. — The  upper  or  supra-diaphragmatic  portion  of  the  alimentary  canal,  through 
which  the  food  merely  passes,  is  straight ;  the  sub-diaphrjigmatic  portion  is  very  much 
convoluted  upon  itself,  but  again  becomes  straight  before  its  termination. 

General  Form. — The  digestive  apparatus  forms  a  cylindrical  continuous  canal,  in  which 
we  have  to  consider  an  external  and  generally  free  serous  surface,  and  an  internal  mu- 
cous surface. 

Struclure. — The  digestive  canal  is  composed  of  four  membranes  or  tunics  :  1 .  The 
most  external  is  the  serous  or  peritoneal  coat,  also  named  the  common  tunic,  because  it  is 
conunon  to  almost  all  the  organs  in  the  abdominal  cavity.  This  membrane,  which  may 
be  regarded  as  an  accessory  tunic,  is  often  incomplete,  and  even  entirely  wanting  through- 
out the  supra-diaphragmatic  portion  of  the  digestive  canal.  At  the  same  time  that  it 
constitutes  the  external  covering  of  this  canal,  it  separates  it  from  the  neighbouring  parts, 
facilitates  its  movements,  and  forms  certain  bands,  which  maintain  the  several  portions 
of  the  canal  more  or  less  fixedly  in  their  proper  situations.  The  serous  membranes,  of 
which  this  external  tunic  is  only  a  dependance,  are  shut  sacs,  which,  on  the  one  hand, 
line  the  walls  of  the  cavities  to  which  they  belong,  and,  on  the  other,  are  reflected  upon 
the  organs  contained  therein,*  without,  however,  including  them  within  their  ovm  prop- 
er cavity. 

A  serous  membrane  may  be  compared  to  a  balloon,  or,  rather,  to  a  double  nightcap ; 
its  internal  surface  is  free,  smooth,  always  moistened  with  serosity,  and  its  parietal  and 
visceral  portions  are  in  contact  with  each  other  :  its  external  surface  is  adherent,  t 

2.  Beneath  the  serous  coat  is  situated  the  muscular  coat,  consisting  of  two  layers :  one  su- 
perficial, composed  of  longitudineil  fibres  ;  the  other  deep,  and  composed  of  circular  fibres. 

These  fibres  are  colourless,  like  almost  all  the  muscles  of  nutritive  or  organic  life.  J 

3.  The  fibrous  coat,  interposed  between  the  muscular  and  mucous  coats,  may  be  regard- 
ed as  constituting  the  framework  of  the  alimentary  canal.  It  consists  of  dense  areolar 
cellular  tissue.^ 

4.  The  mucous  coat  or  membrane  forms  the  internal  lining  of  the  digestive  canal.  Ev- 
ery cavity  having  a  communication  with  the  exterior  is  hned  by  a  mucous  membrane, 
so  called  on  account  of  the  mucus  with  which  it  is  constantly  lubricated. 

In  mucous  membranes  generally,  we  find,  1.  A  dermis  or  chorion,  2.  Papilla  or  villosi- 
ties,  which  give  them  a  velvety  appearance  ;  hence  the  designation  papillary,  villous,  or 
velvety  membrane  frequently  given  to  them.  3.  On  the  outer  surface  of  the  dermis  we 
find  a  very  dense  network  of  capillary  vessels,  which  may  be  completely  injected  from  the 
veins,  but  less  easily  and  less  completely  from  the  arteries.  4.  Either  follicles  or  small 
closed  sacs  are  seen  here  and  there  in  the  substance  of  mucous  membranes  ;  but  they 
are  not  essential,  as  the  name  follicular,  given  to  these  membranes  by  Chaussier  and 
some  other  anatomists,  would  seem  to  indicate. 

*  [Hence  the  terms  parietal  and  visceral,  applied  to  these  two  portions  of  a  serous  membrane  (see  Jig,  of 
the  testis,  letters  p  and  v). 

In  consequence  of  the  existence  of  an  aperture  in  the  free  extremity  of  each  Fallopian  tube,  the  peritoneal 
cavity  in  the  female  is  an  exception  to  the  general  rule,  that  serous  membranes  form  shut  sacs,  not  communi- 
cating with  the  external  medium.] 

t  [Serous  membranes  are  transparent,  colourless,  extremely  thin,  and  highly  distensible  and  elastic.  They 
are  composed  of  a  basis  of  cellular  tissue,  loose  and  connected  to  the  adjacent  tissues  externally,  more  or  less 
condensed  towards  the  inner  and  free  surface  of  the  membrane,  and  covered  with  an  extra- vascular  epithelium, 
consisting  of  a  single  layer  of  nucleated  cells,  Ilattened  into  the  form  of  scales,  and  arranged  parallel  to  that 
surface.  Cilia  have  been  detected  on  many  serous  membranes,  as  on  the  peritoneum  and  pericardium  of  the 
frog  ;  on  the  same  parts,  and  also  on  the  pleura  and  lining  membrane  of  the  ventricles  of  the  brain  in  certain 
mammalia  ;  and  in  the  latter  situation  in  man.  Bloodvessels  ramify  in  the  sub-serous  cellular  tissue,  but  do 
not  penetrate  far  towards  the  free  surface,  where  they  are  entirely  wanting.  Lymphatics  also  exist  in  the 
sub-serous  tissues,  but  have  not  been  found  in  the  membranes  themselves  ;  nor  have  nerves  been  traced  into 
them.     The  fluid  secretion  found  in  serous  cavities  appears  to  be  of  an  albuminous  nature.] 

t  [The  involuntary  muscular  fibres  of  the  alimentary  canal  (according  to  Dr.  VV.  Baly)  consist  of  bands,  va- 
rying from  o^j'g-jjth  to  ,  A  ^ th  of  an  inch  in  diameter,  apparently  formed  of  flattened  tubes,  in  the  parietes  of 
which  are  seen,  at  irregular  intervals,  numerous  transparent  oval  or  linear  bodies,  sometimes  very  difiicult  of 
detection :  they  are  believed  to  be  the  nuclei  of  the  primitive  cells,  from  which  the  fibre  itself  is  developed. 
These  fibres  contain  no  varicose  filaments,  nor  do  they  present  any  transverse  striK,  like  those  of  animal  life 
(see  p.  194).  Moreover,  although  they  have  a  parallel  arrangement  in  the  fasciculi  into  which  they  are  col- 
lected, the  fasciculi  themselves  are  irregularly  interlaced,  at  the  same  time  that  they  all  pursue  a  common 
direction. 

The  muscular  coat  of  nearly  the  entire  alimentary  canal  consists  essentially  of  these  involuntary  or  organic 
muscular  fibres  ;  but  at  the  commencement  and  termination  of  the  canal,  where  the  muscular  systems  of  ani- 
mal and  organic  life  come  into  relation  with  each  other,  this  tunic  appears  also  to  consist  of  fibres  resembling 
those  of  the  voluntary  muscles.  Thus,  at  the  upper  part  of  the  (Esophagus,  fibres  containing  varicose  filaments, 
and  possessing  the  cross  stri<e,  were  detected  by  Schwann  ;  and  it  has  been  shown  by  Valentin  and  Ficinns, 
that  these  exist  all  along  the  oesophagus,  and  that  indistinctly  striated  fibres  are  found  even  at  the  cardiac  end 
of  the  stomachs  of  many  mammalia,  and  of  man.  Similar  fibres  were  observed  by  Ficinus  in  the  rectum,  near 
the  sphincter  ani.] 

I)  [It  is  frequently  called  the  cellular  coat  ;  and,  from  its  white  appearance,  has  been  termed  (like  all  othei 
white  textures)  the  nervous  tunic] 


SPLANCHNOLOGY. 


All  mucous  membranes  are  covered  by  an  extremely  delicate  pellicle,  which  may  be 
readily  detected  by  means  of  a  simple  lens.  Injections  made  by  the  arteries  and  veins 
never  penetrate  it,  nor  is  it  reddened  by  inflammation.  I  have  accidentally  injected  it, 
hovirever,  by  means  of  a  tube  containing  mercury,  used  for  injecting  the  lymphatics  by 
pricking  the  mucous  membrane  in  different  places  as  superficially  as  possible.  The  vas- 
cular network,  thus  injected,  is  exceedingly  delicate ;  the  small  globules  of  mercury 
traversing  it  in  all  directions,  so  as  to  form  rapidly  a  silvery  areolar  layer.  I  have  seen 
this  in  the  mucous  membrane  of  the  nose  ;  on  the  conjunctiva,  both  over  the  sclerotic 
and  over  the  cornea  ;  on  the  mucous  membrane  of  the  vagina,  of  the  tongue,  and  of  the 
cheeks.  It  is  very  remarkable  that  the  mercury  never  passes  from  this  network  ei- 
ther into  the  veins  or  the  arteries ;  and,  moreover,  that  if  the  tube  pierces  a  little  too 
deeply,  the  veins  are  injected,  but  not  the  epidermic  capillary  network.  It  is  evident, 
therefore,  that  this  network  has  no  communication  either  with  the  arteries  or  the  veins. 
It  probably  belongs  to  the  lymphatic  system,  although  I  have  never  observed  the  lymphat- 
ic vessels  filled  from  it.* 

Vessels  and  Nerves. — Vessels  and  nerves  also  enter  into  the  formation  of  the  aliment- 
Fig.  139.  ary  canal :  for  example,  we  find  a  very  abundant  supply  of 

branches  from  the  adjacent  arterial  trunks  ;  an  immense  num- 
ber of  veins,  of  which  those  from  the  sub-diaphragmatic  por- 
tion of  the  canal  terminate  in  the  vena  portae  ;  absorbent  ves- 
sels, divided  into  lymphatics  and  lacteals  ;  and,  lastly,  nerves, 
almost  all  of  which  proceed  from  the  ganglionic  system,  ex- 
cepting the  pneumogastric  and  glosso-pharyngeal  nerves. 

Division  of  the  Digestive  Canal. — The  digestive  canal  has 
been  divided  into  several  parts,  from  differences  both  in  their 
anatomical  characters  and  their  functions.  One  principal  di- 
vision, which  deserves  to  be  retained,  is  into  a  supra-diaphrag- 
matic and  a  sub-diaphragmatic  portion.  The  supra-diaphragmat- 
ic portion  comprehends  the  mouth,  the  pharynx,  and  the  asoph- 
agus.  The  infra-diaphragmatic  portion  includes  the  stomach 
(a  h,  fig.  139),  the  small  intesti7ie,  subdivided  into  the  duodenum 
(b  c),  and  the  jejunum  and  ileum  (c  d) ;  and  the  large  intestine, 
somewhat  arbitrarily  divided  into  the  ceecum  {d  e),  the  colon  {d 
h),  and  the  rectum  (h  i).  The  appendages  of  the  digestive  ca- 
nal consist  of  the  salivary  glands,  connected  with  the  mouth  ; 
of  the  liver  and  the  pancreas,  connected  with  the  duodenum ; 
and  of  the  spleen,  which  may  be  regards'^  .^s  an  appendage  of  the  liver. 

The  Mouth  and  its  Appendages. 

The  mouthy  is  a  cavity  situated  at  the  entrance  of  the  digestive  passages.  It  occu- 
pies the  lower  part  of  the  face,  and  is  situated  between  the  two  jaws,  below  the  nasal 

*  [The  lining  membrane  of  the  digestive  apparatus,  forming  part  of  the  gastro-pulmonary  system  of  the 
mncou.s  membranes,  extends  not  only  throughout  the  entire  alimentary  canal,  but  also  along  the  ducts  of  the 
various  glands  which  pour  their  secretions  into  it. 

Structure  m  general. — Mucous  membranes  are  usually  soft,  pulpy,  incapable  of  great  distension,  easily  la- 
cerated, soraevfhat  opaque,  and  when  free  from  blood,  of  a  pale  grayish  or  ashy  hue.  The  dermis  or  chorion 
(analogous  to  that  of  the  skin)  is  a  basis  of  cellular  tissue,  of  very  variable  thickness  ;  its  attached  surface  is 
connected  to  the  subjacent  textures,  either  immovably,  as  in  the  nasal  cavities  and  on  the  tongue,  or  loosely, 
as  in  the  gullet  and  stomach.  The  pellicle  or  epithehum  with  which  its  surface  is  always  covered  (correspond- 
ing to  the  epidermis  of  the  skin)  adso  varies  much  in  thickness  in  different  situations  ;  it  consists  of  transpa- 
rent nurJeated  cells,  according  to  the  form  and  arrangement  of  which  it  receives  its  name.  Thus,  in  the 
squamous  epithelium,  there  are  generally  (as  in  the  mouth  and  gullet)  several  layers  of  cells  ;  of  these  the 
deepest  are  vesicular,  and  contain  a  comparatively  large  nucleus  ;  those  im  the  surface  are  flattened  out  into 
polygonal  scales,  from  the  centrj  of  which  the  nucleus  has  nearly  disappeared,  while  the  intermediate  cells 
present  intermediate  transitional  forms.  The  nucleated  cells  of  the  columnar  epithelium  (found,  for  example, 
in  the  stomach  and  intestines)  are  developed  into  oblong  cylinders,  arranged  in  a  single  scries,  like  basaltic 
columns,  perpendicularly  to  the  surface  of  the  dermis.  In  some  situations,  as  in  the  nasal  cavities  and  air 
passages,  cilia  are  attached  to  the  free  extremities  of  the  cylinders  of  the  columnar  epithelium,  but  no  cilia 
have  been  detected  in  any  part  of  the  alimentary  canal  of  man,  or  the  warm-blooded  animals  :  the  superficial 
cells  of  the  epithelium  of  mucous  membranes  are  continually  being  thrown  off  by  a  process  of  desquamation. 
The  different  mucous  membranes  differ  in  vascularity  ;  the  network  of  capillary  vessels  in  the  dermis  becomes 
closer  or  denser  near  its  surface  ;  the  lymphatic  vessels  also  form  a  network  in  the  same  situation;  but  the 
epithelium,  though  organized,  is,  as  stated  in  the  text,  perfectly  extra-vascular. 

Mucous  membranes  are  also  more  or  less  abundantly  supplied  with  nerves. 

When  boiled  they  yield  no  gelatine,  or,  rather,  only  as  much  as  would  proceed  from  the  cellular  tissue  and 
vessels  they  contain.  The  fluid  secreted  by  them,  or  mucus,  is  viscid,  transparent,  and  colourless,  miscible 
with,  but  not  soluble  in  water,  and  not  coagulated  by  heat.  It  contains,  besides  the  desquamated  epithelium 
scales,  proper  granular  globules,  yjg-ff  '"•''^  '"  diameter,  and  having  a  very  close  resemblance  to  the  globules 
of  pus.  According  to  Berzelius,  mucus  consists  of  water,  a  few  salts,  albumen,  and  a  peculiar  animal  sub- 
stance, which  he  calls  mucous  matter.  This  latter,  when  dried,  swells  on  being  placed  in  water,  but,  like- 
fresh  mucus,  is  insoluble  in  that  fluid, either  hot  or  cold;  it  is  shghtly  soluble  in  dilute  acetic  and  nitric  acids, 
and  in  caustic  alkalies. 

The  peculiarities  presented  by  particular  portions  of  the  mucous  membranes,  and  the  structure  of  the  pa- 
pillae, villi,  follicles,  &c.,  found  in  some  parts  of  them,  will  be  separately  noticed,  as  ojiportunity  offers.) 

t  The  meaning  of  the  word  mouth,  in  anatomy,  differs  from  the  ordinary  acceptation  of  the  term,  which  is 
•sually  applied,  not  to  the  buccal  cavity,  but  to  its  orifice. 


THE    LIPS.  32d 

fossffi,  between  the  cheeks,  behind  the  lips,  and  in  front  of  the  pharynx.     It  constitutes 
a  very  complicated  apparatus,  in  which  are  per-  p^g  j4q 

formed  the  several  acts  of  mastication,  tasting, 
and  insalivation,  the  commencement  of  the  act  of 
deglutition,  and  the  articulation  of  sounds. 

The  dimensions  of  the  buccal  cavity  are  great- 
er than  those  of  the  succeeding  portion  of  the  ali- 
mentary canal ;  hence  bodies  may  be  introduced 
into  it  which  are  too  large  to  pass  through  the 
constricted  parts  of  that  canal.*  The  size  of  the 
mouth  presents  every  intermediate  degree  be- 
tween complete  closure  with  the  jaws  in  contact 
and  leaving  no  interval  between  them,  and  ex- 
treme expansion,  when  the  buccal  cavity  repre- 
sents a  quadrangular  pyramid,  the  base  of  which 
is  directed  forward,  and  the  apex  backward.  Au 
increase  in  the  capacity  of  the  mouth  may  also 
be  effected  in  the  transverse  direction  by  the  dis- 
tension of  the  cheeks,  and  in  the  antero-posterior 
direction  by  a  projection  of  the  lips  fiJrward. 

In  studying  the  relative  proportions  of  the  sev- 
eral diameters  of  the  buccal  cavity,  it  is  found 
that  none  of  them  predominates  in  man,  while, 
in  the  lower  animals,  the  antero-posterior  is  by 
far  the  longest :  this  depends  partly  on  the  great  size  of  their  nasal  cavities,  and  partly 
on  the  length  of  their  jaws.  In  connexion  with  this  subject,  we  may  remark,  that  in 
the  animal  series  there  is  an  inverse  ratio  between  the  size  of  the  cavity  of  the  cranium 
and  that  of  the  gustatory  and  olfactory  cavities. 

In  man,  the  direction  or  axis  of  the  mouth  is  horizontal — an  arrangement  which  is  con- 
nected with  his  destination  for  the  biped  position.  If  man  assumed  the  attitude  of  a 
quadruped,  the  axis  of  his  mouth  would  be  vertical ;  whereas,  in  the  lower  animals,  it  is 
directed  obliquely  to  the  horizon. 

Form. — The  mouth  {Jig.  140)  represents  a  perfectly  symmetrical  oval  cavity,  the  great 
extremity  of  which  is  in  front.  It  has  an  upper  wall,  viz.,  the  arch  of  the  palate  (a) ;  a 
lower  wall,  consisting  principally  of  the  tongue  (i) ;  a  posterior  icall,  formed  by  the  velum 
palati  (c) ;  an  anterior  wall,  composed  of  the  lips  {d)  on  one  plane,  and  of  the  alveolar 
arches  and  the  teeth  (e)  on  another ;  and  two  lateral  walls,  formed  by  the  same  arches, 
by  the  teeth,  and  by  the  cheeks.  It  lias  two  openings  :  one  anterior  (m),  constituting  the 
orifice  of  the  mouth  ;  the  other  posterior  {2,  Jigs.  140,  141),  establishing  a  communication 
between  the  buccal  cavity  and  the  pharynx,  and,  on  account  of  its  narrowness,  called  the 
isthmus  of  the  fauces . 

We  shall  now  describe  these  parts  in  succession,  excepting  the  maxillary  bones  and 
the  teeth,  which  have  been  already  treated  of  The  salivary  glands,  which  pour  their 
secretions  into  the  buccal  cavity,  will  be  described  as  appendages  to  it. 

The  Lips. 

The  lips,  forming  the  anterior  wall  of  the  mouth,  are  two  movable,  extensible,  and 
contractile  curtains,  which  circumscribe  its  orifice.  They  are  distinguished  into  upper 
and  lower.  Their  direction  is  vertical,  like  that  of  the  alveolar  and  dental  arches,  upon 
which  they  are  applied.  This  direction  is  peculiar  to  the  human  species,  and  is  more 
marked  in  the  Caucasian  race;  lips  projecting  forward,  like  those  of  the  lower  animals, 
and  not  placed  upon  the  same  vertical  plane,  give  a  mean  expression  to  the  physiogno- 
my. The  depth  of  the  lips  is  measured  by  that  of  the  alveolar  and  dental  arches.  The 
upper  is  deeper  than  the  lower  lip. 

The  two  lips  offer  for  our  consideration  an  anterior  or  cutaneous  surface,  a  posterior 
or  mucous  surface,  an  attached  and  a  free  border,  and  two  commissures. 

The  Anterior  Surface. — In  the  upper  lip  this  surface  presents  along  the  median  line  a  ver- 
tical furrow,  the  sub-nasal  groove,  commencing  at  the  septum  of  the  nose,  and  termina- 
ting belovi^  in  a  tubercle,  which  is  more  or  less  prominent  in  different  individuals.  This 
furrow  is  the  vestige  of  a  division  in  the  lip,  natural  to  many  mammalia.  The  malfor- 
mation, termed  single  hare-lip,  always  occupies  one  of  the  edges  of  this  groove  ;  in  double 
hare-lip  both  of  them  are  affected.  On  each  side,  the  upper  lip  is  convex,  and  covered 
with  a  slight  down  in  the  female,  and  before  puberty  in  the  male,  but  after  that  period 
with  long  and  stiff  hairs  directed  obliquely  outward.  The  aspect  of  the  anterior  surface 
of  the  lower  lip  is  inclined  a  little  downward ;  the  middle  portion  only  of  this  lip,  which 
presents  no  median  depression,  is  covered  with  hairs. 

*  As  a  peneral  rule,  the  proportion  between  the  different  parts  of  the  alimentary  canal  is  such,  that  the  up- 
per portion  will  not  admit  bodies  too  Urge  for  the  lower ;  and  though  the  buccal  cavity  forms  an  exception  to 
the  rule,  it  is  because  the  food,  while  it  remains  in  that  situation,  is  under  the  influence  ot  the  will. 


326  SPLANCHNOLOGY. 

The  Posterior  Surface. — Each  lip  is  free  behind,  excepting  in  the  median  h'ne,  where 
we  find  a  small  fold  of  mucous  membrane  called  the  frcenum  labii :  it  is  more  marked  m 
the  upper  than  in  the  lower  lip.  This  surface  is  always  moist,  and  is  in  contact  -with 
the  alveolar  and  dental  arches.  The  complete  independence  of  the  lips,  as  regards  the 
maxillary  bones,  explains  the  extreme  mobility  of  these  membranous  organs.* 

Adherent  Borders  of  the  Lips. — The  lips  are  bounded  at  their  posterior  surface  by  the 
reflection  of  the  mucous  membrane  upon  the  jaw,  so  that  there  is  a  deep  and  very  re- 
markable furrow  between  the  lips  and  the  maxillary  bones,  which  may  be  regarded  as 
an  anterior  buccal  cavity,  or  the  vestibule  of  the  mouth.  The  upper  lip  is  bounded  in  front 
by  the  base  of  the  nose ;  on  each  side  it  is  separated  from  the  cheeks  by  the  projection 
of  the  inner  margin  of  the  levator  labii  superioris  alaeque  nasi ;  the  lower  lip  is  bounded 
in  the  median  line  by  a  transverse  depression  situated  between  it  and  the  chin,  called 
the  mento-labial  furrow,  which  is  remarkable  for  the  perpendicular  direction  of  the  hairs 
growing  upon  it ;  on  each  side  it  is  separated  from  the  cheeks  by  the  projecting  inner 
margin  of  the  triangularis  oris. 

The  hue  or  furrow  which  separates  cm  either  side  the  lips  from  the  cheek  commences 
at  the  ala  of  the  nose,  and  is  c£illed  the  naso-labial  line  .•+  it  would  be  more  appropriately 
named  the  bucco-laJnal  line  or  furrow. 

The  boundaries  between  the  lips  and  the  cheeks  are,  then,  entirely  artificial ;  the  two 
lips,  taken  together,  represent  an  ellipse,  the  longest  diameter  of  which  is  transverse. 

The  Free  Borders  of  the  Lips. — ^The  free  borders  of  the  lips  are  rounded,  are  covered 
by  a  red  integument,  intermediate  in  character  between  skin  and  mucous  membrane,  and 
are  marked  by  folds  or  wrinkles  directed  at  right  angles  to  the  length  of  the  lips,  and 
produced  by  the  contraction  of  the  orbicularis  oris  muscle.  These  free  borders,  which 
are,  as  it  were,  everted,  especially  that  of  the  lower  lip,  present  anteriorly  a  well-marked 
line  of  separation  between  the  skin  and  the  mucous  membrane  ;  they  describe  an  undu- 
lating line,  which  attracts  the  attention  of  the  painter  more  than  that  of  the  anatomist. 

The  chief  characters  of  the  free  margin  of  the  upper  lip  are,  a  slight  projection  in  the 
middle  hne,  and  a  slight  depression  on  either  side  :  those  of  the  free  border  of  the  lower 
lip  are  a  median  depression  and  two  lateral  projections  ;  on  meeting  together,  these  bor- 
ders come  into  accurate  contact,  and  completely  close  the  opening  of  the  mouth.  The 
free  margins  of  the  lips  are,  moreover,  their  thickest  part,  and  they  are  thicker  in  the 
middle  than  at  each  extremity  ;  their  thickness  also  varies  greatly  in  different  individ- 
uals. In  general,  thick  lips  are  regarded  as  indicating  a  scrofulous  diathesis ;  but  in 
forming  an  opinion  upon  this  subject,  it  is  necessary  to  distinguish  carefully  between 
size  resulting  from  hypertrophy  of  the  muscular  layer,  and  that  which  is  caused  by  an 
excess  of  skin  and  cellular  tissue.  In  the  Ethiopian  race,  the  size  of  the  lips  is  entirely 
due  to  the  great  development  of  the  muscles. 

The  Commissures. — The  lateral  extremities  of  the  free  margins  of  the  lips  are  thin,  and 
by  their  union  form  the  angles  or  commissures  of  the  lips  (from  committo,  to  join  together). 

The  Anterior  Orifice  of  the  Mouth. — The  free  edges  of  the  lips  intercept  a  transverse 
fissure,  viz.,  the  anterior  opening  of  the  mouth.  The  variable  size  of  this  orifice  in  man 
has  given  rise  to  the  distinctions  of  middle-sized,  large,  and  small  mouths  :  the  difference, 
however,  is  confined  to  the  opening,  and  does  not  at  all  affect  the  buccal  cavity  properly 
so  called.  The  anterior  opening  of  the  lips  is  also  exceedingly  dilatable,  and,  accord- 
ingly, admits  the  introduction  of  very  large  bodies,  and  renders  the  exploration  of  every 
part  of  the  cavity  of  the  mouth  comparatively  easy. 

Structure  of  the  Lips. — The  lips  are  composed  of  two  tegumentary  layers,  one  cutane- 
ous, the  other  mucous ;  of  a  muscular  layer ;  of  a  series  of  glands ;  and  of  vessels, 
nerves,  and  cellular  tissue. 

The  Cutaneous  Layer. — This  is  remarkable  for  its  density  and  thickness,  for  the  size 
of  the  hair  follicles,  which  are  partially  situated  beneath  it,  and  for  its  intimate  adhesion 
to  the  muscular  layer ;  so  that  it  is  impossible  to  separate  them  by  dissection  without 
encroaching  upon  one  or  the  other.  This  layer  may  be  regarded  as  the  framework  of 
the  lips.  It  is  endowed  with  an  exquisite  sensibility,  and,  in  many  animals,  possesses 
so  delicate  a  sense  of  touch,  that  the  slightest  movement  of  the  extremities  of  the  long 
hairs  with  which  it  is  provided  at  once  warns  the  animal  of  the  presence  of  approach- 
ing objects. 

The  Mucous  Layer. — This  is  remarkable  from  the  existence  of  an  epithelium  upon  it, 
which  can  be  very  easily  demonstrated.  It  covers  the  free  edge  of  the  hps,  so  that,  by 
a  rare  exception,  a  portion  of  this  mucous  membrane  is  habitually  exposed  to  the  exter- 
nal air.    It  adheres  more  firmly  at  the  free  edge  of  the  lip  than  elsewhere.t 

The  Glandular  Layer. — This  is  a  thick  layer,  situated  between  the  mucous  and  the 

*  Mammalia  alone  have  lips  that  are  movable,  independently  of  the  jaws  ;  but  this  independence  is  still 
more  marked  in  man. 

t  Much  importance  is  attached  to  this  furrow  in  semeiology.  It  is  termed  the  abdominal  line,  because  it 
becomes  remarkably  distinct  in  diseases  of  the  abdomen. 

t  [The  mucous  membrane  upon  the  free  borders  of  the  lip  is  provided  with  papillse.  Its  epithelium,  and, 
indeed,  that  of  the  entire  mouth,  is  sqiuanous.l 


THE  LIPS.  327 

..muscular  layers,  and  causing  an  elevation  of  the  former.    It  consists  of  small  spheroida. 

i^glands  of  unequal  size,  placed  close  to  each  other,  but  perfectly  distinct ;  when  examined 

with  a  lens,  they  resemble  small  salivary  glands,  each  being  provided  with  an  excretory 

duct,  opening  by  a  separate  orifice  upon  the  posterior  siurface  of  the  mucous  membrane.* 

These  are  true  labial  salivary  glands,  and  not  muciparous  follicles. 

The  Muscular  Layer. — This  is  composed  essentially  of  a  single  proper  muscle,  the  or- 
bicularis oris,  into  which  almost  all  the  muscles  of  the  face  are  inserted,  viz.,  the  levator 
labii  superioris  alaeque  nasi,  the  levator  labii  superioris,  the  depressor  alae  nasi,  the  naso- 
labialis,  and  the  zygomaticus  minor  (where  it  exists)  for  the  upper  lip ;  the  quadratus 
menti  and  the  levator  labii  inferioris  for  the  lower  lip  ;  the  buccinator  (which  we  have 
regarded  as  forming  the  orbicularis  by  its  bifurcation  extending  to  both  lips),  and  the 
zygomaticus  major,  the  triangularis  oris,  the  levator  anguli  oris,  and  the  risorius  of  San 
torini  (where  it  exists)  to  the  commissures.  Including  the  orbicularis  oris,  there  are 
twenty-five  muscles.  The  differences  presented  by  the  free  edges  of  the  lips  in  differ- 
ent individuals  depend  upon  variations  in  the  thiclcness  of  the  corresponding  portion  of 
the  orbicularis. 

No  fibrous  tissue  enters  into  the  composition  of  the  lips  and  their  commissures,  which 
are  exclusively  formed  of  fleshy  fibres  :  hence  they  are  extremely  extensible,  a  circum- 
stance of  which  the  surgeon  avails  himself  in  operating  upon  parts  situated  in  the  buc- 
cal cavity  and  pharynx. 

Vessels,  Nerves,  and  Cellular  Tissue. — Few  parts  are  so  abundantly  provided  with  vessels 
and  nerves  as  the  Jips.  The  arteries  of  the  lips  are  derived  from  two  principal  sources  : 
the  coronary  arteries  arise  from  the  facial ;  the  buccal,  infra-orbital,  and  alveolar  arteries 
destined  for  the  upper  lip,  and  the  mental  artery  for  the  lower  lip,  arise  from  the  internal 
maxillary.  The  sub-mental  artery,  a  branch  of  the  facial,  and  the  transversalis  faciei,  a 
branch  of  the  temporal,  also  give  off  some  ramifications  to  the  lips.  The  veins  bear  the 
same  names,  and  follow  the  same  direction  as  the  arteries ;  the  lymphatic  vessels,  which 
are  little  known,  terminate  in  the  glands  at  the  base  of  the  jaw.  The  nerves  are  derived 
from  two  distinct  sources,  viz.,  from  the  fifth  and  the  seventh  pairs  of  cranial  nerves. 

The  cellular  tissue  contained  in  the  substance  of  the  lips  is  essentially  of  a  serous 
nature.  It  is  liable  to  a  considerable  amount  of  serous  infiltration ;  but  even  in  the  fat- 
test individuals  it  contains  only  a  very  small  quantity  of  adipose  tissue. 

Development. — According  to  Blumenbach  and  most  modem  anatomists,  the  upper  lip 
is  originally  developed  from  three  points  or  three  distinct  parts :  one  median  and  two 
lateral.  Some  have  even  gone  farther,  and  have  maintained  that  the  median  point  itself 
is  originally  formed  of  two  lateral  halves,  which  become  united  at  a  very  early  period. 
This  hypothesis  is  founded  partly  upon  the  nature  of  the  divisions  in  simple  and  double 
hare-lip,  each  of  which  has  been  assumed  to  be  nothing  more  than  an  arrest  of  develop- 
ment ;  also,  upon  the  mode  of  development  of  the  superior  maxillary  bones,  the  alveolar 
border  of  which,  it  is  said,  is  composed  of  four  pieces  :  two  median  or  incisor,  and  two 
lateral ;  and,  lastly,  upon  the  permanent  existence  of  these  divisions  in  some  animals. 
In  opposition  to  this  view,  however,  we  may  state,  first,  the  absence  in  the  human  foetus 
of  distinct  bony  pieces,  corresponding  to  the  ossa  incisiva  of  the  lower  animals,  for  all 
that  can  be  distinguished  is  a  fissure,  the  mere  trace  of  a  separation  (see  Development  of 
the  Superior  Maxilla,  p.  51) ;  and,  secondly,  that  at  no  period  of  foetal  life  can  we  demon- 
strate the  existence  of  any  division  in  the  upper  lip.  This  lip  has  always  appeared  to 
me  to  consist  of  a  single  piece  from  the  earliest  period  of  its  formation.  The  same 
may  be  said  of  the  lower  lip,  which,  according  to  authors,  is  developed  from  two  lateral 
halves.  At  no  period  of  foetal  life  can  any  such  division  be  detected.  +  I  do  not  even 
know  an  example  of  malformation  in  which  such  an  arrangement  existed. 

The  length  of  the  lips  of  the  new-bom  infant  is  well  adapted  for  the  act  of  sucking,  and 
depends  upon  the  absence  of  the  teeth.  To  the  same  cause,  and  to  the  wasting  of  the 
alveolar  borders,  the  length  of  the  hps  in  advanced  age  must  be  referred. 

Uses. — The  lips,  constituting  the  anterior  wall  of  the  mouth,  form  a  sort  of  barrier  in 
front  of  the  teeth  and  alveolar  arches,  by  which  the  saliva  is  retained  within  that  cavity. 
So  great  is  the  importance  of  the  lips  in  preventing  a  continual  escape  of  the  saliva,  that 
in  cases  where  they  have  been  destroyed,  the  constant  draining  away  of  that  fluid  may 
become  a  cause  of  exhaustion,  and  even  of  death.J 

They  are  employed,  also,  in  drinking,  sucking,  and  blowing  ;  in  playing  upon  wind-in- 
struments, and  in  uttering  articulate  sounds.  They  are  also  of  great  importance  in  the 
expression  of  the  passions,  which,  as  we  have  seen,  influence  all  the  muscles  of  the  face. 
Pride,  contempt,  joy,  grief,  anger,  and  every  possible  gradation  Of  feeling,  are  depicted 
in  a  striking  manner  upon  the  outline  of  the  lips.     The  mouth  is  more  particularly  the 

*  When  these  orifices  are  obliterated,  the  dilated  excretory  ducts  are  transformed  into  salivary  cysts,  which 
may  acquire  a  very  large  size. 

t  The  admirable  researches  of  M.  Velpeau  upon  embryology  fully  confirm  the  results  at  which  1  have  ar- 
rived. 

t  This  use  is  principally  confined  to  the  lower  lip,  and  it  is  remarkable  that  this  lip  is  never  affected  by  con- 
genital fissure.  Another  singular,  and  also  totally  inexplicable  fact,  is,  that  cancer,  which  is  so  common  a  dis 
ease,  never  affects  the  upper,  but  invariably  the  lower  lip 


\ 


328  SPLANCHNOLOGY. 

seat  of  grimaces,  which  are  nothing  more  than  the  expression  of  passions  ridiculously 
exaggerated. 

The  Cheeks. 

The  cheeks  form  the  lateral  walls  of  the  mouth  and  the  sides  of  the  face.  They  are 
bounded  internally  by  the  reflection  of  the  mucous  membrane  upon  the  maxillary  bones ; 
externally  their  limits  are  much  less  defined,  and  are  thus  determined  on  each  side  of 
the  face  ;  in  front,  by  the  bucco-labial  furrow,  which  separates  them  from  the  lips  ;  behind, 
by  the  posterior  border  of  the  ramus  of  the  lower  jaw  ;  above,  by  the  base  of  the  orbit ; 
and  below,  by  the  base  of  the  lower  jaw.  The  cheeks,  then,  comprise  three  very  distinct 
regions  :  the  malar,  the  masseteric,  and  the  buccal,  properly  so  called.  Each  cheek  is 
quadrilateral  in  form,  and  presents,  1.  An  external  or  cutaneous  surface,  on  which  is  ob- 
served, above,  tl)e  projection  of  the  cheek,  called  the  malar  eminence,  and  lower  down,  a 
surface,  which  is  convex  and  smooth  in  stout  persons,  but  hollow  and  wrinkled  in  the 
emaciated ;  2.  An  internal  or  mucous  surface,  free,  and  corresponding  to  the  alveolar  and 
dental  arches.  On  this  surface  is  situated  the  orifice  of  the  Stenonian  duct,  opposite  the 
interval  which  separates  the  first  from  the  second  upper  large  molar  tooth. 

Structure. — Each  cheek,  properly  so  called,  is  composed  of  the  following  parts :  the 
malar  bone  and  the  ramus  of  the  lower  jaw  ;  a  cutaneous  layer,  increased  in  thickness 
by  a  great  quantity  of  fat ;  a  mucous,  a  glandular,  a  muscular,  and  an  aponeurotic  layer ; 
some  vessels  and  nerves,  and  an  excretory  duct.  We  shedl  make  a  few  remarks  upon 
these  different  layers,  commencing  with  the  skin. 

The  skin  is  remarkable  for  its  firmness  and  vascularity  over  the  cheek  bone,  and  also 
for  the  facility  with  which  it  is  injected,  or  becomes  pale  under  the  influence  of  the  moral 
feelings  ;  it  is  covered  with  hair  on  the  lower  and  back  part  in  the  adult  male 

The  mucous  membrane  is  a  continuation  of  that  of  the  lips,  and  presents  the  same  char- 
acters. 

The  glandular  layer  is  formed  by  the  buccal  salivary  glands,  which  exactly  resemble  the 
labial  glands,  but  are  smaller,  and,  like  them,  cause  projections  of  the  mucous  membrane, 
upon  which  they  open  by  distinct  orifices.  Two  of  these  glands  have  obtained  a  partic- 
ular appellation,  because  they  are  not  subjacent  to  the  mucous  membrane,  but  are  situ- 
ated between  the  buccinator  and  the  masseter  muscles  :  they  are  called  the  molar  glands. 
Their  excretory  ducts  open  opposite  the  last  molar  tooth. 

The  muscular  layer  is  formed,  in  the  masseteric  region,  by  the  masseter  and  a  part  of 
the  platysma ;  in  the  malar  region,  by  the  orbicularis  palpebrarum ;  in  the  buccal  region, 
properly  so  called,  by  the  buccinator,  and  the  two  zygomatici. 

The  aponeurotic  layer  is  formed  by  the  aponeurosis  of  the  buccinator  muscle. 

The  adipose  layer  is  thin  in  the  malar  and  masseteric  regions,  and  very  thick  in  the 
buccal  region,  properly  so  called.  Bichat  has,  moreover,  pointed  out  a  mass  of  fat  in  the 
substance  of  the  cheek,  between  the  buccinator  and  the  masseter.  It  is  highly  devel- 
oped in  the  infant,  and  vestiges  of  it  are  found  even  in  the  most  emaciated  individuals, 
and  in  extreme  old  age. 

The  arteries  of  the  cheeks  come  partly  from  the  facial  and  the  transverse  artery  of 
the  face,  and  partly  from  the  internal  maxillary  :  the  branches  from  the  internal  maxil- 
lary belong  to  the  infra-orbital,  the  inferior  dental,  the  buccal,  the  masseteric,  and  the 
edveolar  arteries. 

The  veins  bear  the  same  name,  and  follow  the  same  course,  as  the  arteries. 

The  lymphatic  vessels  pass  into  the  cervical  and  parotid  lymphatic  glands. 

The  nerves  of  the  cheeks,  like  those  of  the  lips,  are  derived  from  two  sources,  viz., 
the  buccal  and  malar  nerves,  from  the  portio  dura  of  the  seventh  pair,  and  the  buccal, 
masseteric,  infra-orbital,  and  mental  branches  of  the  fifth  pair. 

The  cheek  is  perforated  by  the  duct  of  Steno  {s,  fig.  144),  which  runs  horizontally  for- 
ward, below  the  malar  bone. 

Development. — The  absence  of  the  teeth,  the  presence  of  a  large  quantity  of  fat  (more 
especially  the  great  size  of  the  mass  above  noticed),  the  want  of  height  in  the  superior 
maxilla  from  the  non-development  of  the  sinus,  and,  lastly,  the  obtuse  angle  of  the  lower 
jaw,  give  to  the  cheek  of  the  infant  its  characteristic  fulness.  The  loss  of  the  teeth, 
and  the  wasting  of  the  alveolar  borders  in  the  aged,  diminish  the  inter-maxillary  space  ; 
so  that  their  emaciated  cheeks  become  disproportionately  long,  and,  consequently,  dis- 
play a  looseness  which  forms  one  of  the  chief  peculiarities  in  their  physiognomy.  At 
puberty,  the  cheeks  of  the  male  are  covered  with  hair. 

Uses. — The  cheeks  form  lateral  active  walls  of  the  mouth,  which,  closely  applying 
themselves  against  the  alveolar  arches  and  teeth,  force  the  food  between  the  latter,  and 
thus  assist  in  mastication.  They  are  employed,  also,  in  suction,  in  the  articulation  of 
sounds,  and  in  plapng  upon  wind-instruments.  In  the  expression  of  the  passions,  they 
assist  rather  by  changes  in  their  colour  than  by  any  distinct  movements. 

The  cheeks  and  the  lips  constitute  the  outer  wall  of  a  supernumerary  buccal  cavity, 
of  which  the  inner  wall  is  formed  by  the  alveolar  borders  and  the  teeth.  This  cavity,  a 
sort  of  vestibule  to  the  buccal  cavity,  properly  so  called,  is  very  dilatable.     It  mav  be 


THE   PALATINE   ARCH   AND   THE    GUMS.  329 

tfuusidered  as  a  kind  of  reservoir,  in  which  the  food  is  deposited,  in  Older  to  be  submitted 
in  successive  portions  to  the  action  of  the  masticatory  organs.  This  vestibular  buccal 
cavity  is  provided  with  labial  and  buccal  salivary  glands.  It  is  also  interesting  to  find 
that  the  parotid  glands,  the  largest  of  all  the  salivary  glands,  pour  their  secretion  into 
this  cavity. 

The  Palatine  Arch  and  the  Gums. 
The  palatine  arch,  or  the  hard  palate  (a,  fig,  140),  constitutes  the  Tipper  wall  of  the  buc- 
cal cavity.  It  has  the  form  of  a  parabolic  arch,  bounded  in  front  and  on  either  side  by 
the  teeth,  and  behind  by  the  velum  palati,  into  which  it  is  continued  without  any  dis- 
tinct line  of  demarcation.  Upon  it  we  observe,  in  the  median  line,  an  antero-posterior 
raphe,  at  the  anterior  extremity  of  which  is  a  tubercle  corresponding  to  the  lower  orifice 
of  the  anterior  palatine  canal.  This  tubercle  has  been  incorrectly  stated  by  physiolo- 
gists to  be  endowed  with  a  peculiar  sensibility  ;  on  each  side  and  in  front  there  are  trans- 
verse ridges,  more  or  less  marked  in  different  individuals,  which  represent  the  still  more 
highly-developed  ridges,  bars,  or  calcareous  concretions,  which  render  the  surface  of  the 
roof  of  the  palate  in  some  animals  so  rugged.  Posteriorly,  the  roof  of  the  palate  is  per- 
fectly smooth. 

Structure. — The  constituent  parts  of  the  palatine  arch  are  an  osseous  framework,  a 
fibro-mucous  membrane,  a  layer  of  glands,  with  vessels  and  nerves. 

The  framework  consists  of  the  bony  palate  already  described  :  it  is  thicker  in  front 
than  behind,  and  is  held  up  in  the  middle  by  the  sort  of  column  formed  by  the  vomer  and 
the  perpendicular  plate  of  the  ethmoid,  and  behind  and  on  each  side  by  the  vertical  por- 
tions of  the  palate  bones,  and  by  the  pterygoid  processes.  We  have  already  noticed  the 
asperities  which  it  presents,  and  which  appear  to  have  no  other  object  than  to  secure 
the  intimate  adhesion  of  the  fibro-mucous  membrane  to  the  bones. 

The  Palatine  and  Gingival  Membrane. — This  mucous  membrane  is  remarkable  for  its 
whitish  colour ;  for  the  thickness  of  its  epithelium,  especially  in  front ;  for  the  thickness 
and  density  of  its  chorion,  which  even  approaches  to  that  of  the  corresponding  tissue  in 
the  skin ;  for  its  close  adhesion  to  the  bones,  into  which  the  chorion  sends  off  well-mark- 
ed fibro-cellular  prolongations  ;  and,  lastly,  for  the  great  number  of  orifices  with  which 
it  is  perforated,  especially  behind.  This  excessive  thickness  of  the  palatine  membrane, 
however,  is  observed  only  anteriorly,  and  most  particularly  so  behind  the  incisor  teeth. 
The  Glandular  Layer. — In  the  median  line  the  palatine  membrane  is  blended  with  the 
periosteum  of  the  bones,  but  on  each  side  it  is  separated  from  it  by  a  very  thick  layer  of 
glands,  which  are  sometimes  arranged  in  regular  rows  along  the  antero-posterior  groove 
presented  by  the  palatine  arch.  These  palatine  salivary  glands  are  exactly  similar  to  the 
labial  and  buccal  glands  already  described ;  they  are  much  more  numerous  behind  than 
in  front,  and  open  upon  the  membrane  by  a  number  of  orifices  visible  to  the  naked  eye. 
There  are  often  two  openings  mud  more  distinctly  marked  than  the  rest,  situated  one 
on  either  side  of  the  posterior  extiemity  of  the  median  raphe. 

The  Gums. — The  description  of  the  peculiar  tissue  of  the  gums,  to  which  some  allusion 
has  been  made  in  speaking  of  the  teeth,  naturally  follows  that  of  the  palatine  membrane. 
The  term  gums  {ovXa)  is  applied  to  those  portions  of  the  buccal  mucous  membrane  which 
surround  the  teeth.  They  are  distinguished  from  the  rest  of  that  membrane  by  their 
intimate  adhesion  to  the  periosteum,  by  their  thickness,  and  especially  by  their  almost 
cartilaginous  density,  which  enables  them  to  resist  the  shocks  of  hard  bodies  during  mas- 
tication. In  this  latter  respect,  and  in  regard  to  their  want  of  sensibility,  the  gums 
closely  resemble  the  contiguous  portions  of  the  palatine  membrane.  They  commence 
about  a  line  from  the  base  of  the  alveoli,  their  limits  being  marked  by  a  scalloped  ridge. 
Having  reached  the  free  margins,  i.  e.,  the  base  of  the  alveoli,  the  gums  continue  their 
course  for  the  space  of  about  a  line  beyond  that  point,  as  far  as  the  neck  of  the  teeth, 
where  they  become  reflected  upon  themselves.  The  point  of  reflection  is  a  free  border 
of  a  semilunar  shape,  corresponding  to  the  indented,  and,  as  it  were,  festooned  border 
of  each  alveolus.  The  denticulations  or  longest  portions  of  the  gums  correspond  to  the 
intervals  between  the  teeth,  in  which  situation  the  processes  of  the  gum,  covering  the 
anterior  and  posterior  surfaces  of  the  alveoli,  communicate  with  each  other. 

The  reflected  portion  of  the  gum,  though  not  adhering  to,  is  in  contact  with,  all  that 
portion  of  the  root  of  the  tooth  which  projects  above  the  alveolus  ;  it  then  dips  into  the 
cavity  of  the  latter,  so  as  to  form  the  alveola-dental  periosteum,  which,  as  we  have  already 
seen,  is  a  powerful  means  of  connecting  the  fang  of  the  tooth  to  its  socket.  The  tissue 
of  the  gums  appears  to  be  provided  with  particular  follicles  for  the  secretion  of  the  tar- 
tar.* It  varies  much  in  different  individuals,  both  in  colour  and  in  density.  One  of  its 
most  peculiar  characters  is  the  singular  effect  produced  on  it  by  scurvy  and  by  mercury, 
under  the  influence  of  which  agents  it  becomes  softened  and  fungous,  easily  bleeds,  and 
furnishes  a  large  quantity  of  tartar.*  Another,  but  purely  anatomical  character,  conbists 
•'n  its  largely-developed  openings  or  pores,  which,  in  a  particular  light,  an  even  vii^ible 

*  [These  are  nuutMis  follicles  :  the  tartar  is  now  known  to  be  merely  a  deposite  from  the  saliva  ;  its  inert  ascc 
amount  during-  1..1  i\t.ri:il  salivation  is,  therefore,  readily  accounted  tor.l 

Tt 


3iro  SPLANCHNOLOGY. 

to  the  naked  eye.  The  gums  are  almost  insensible  when  divided  by  cutting  instruments  ; 
but  the  pressure  exerted  upon  them  by  the  teeth,  during  the  eruption  of  the  latter,  often 
gives  rise  to  the  most  serious  affections. 

Vessels  and  Nerves  of  the  Roof  of  the  Palate  and  the  Gums. — The  arteries  arise,  seme 
from  the  internal  maxillary,  viz.,  the  posterior  palatine,  the  alveolar,  the  infra-orbital, 
and  the  mental  branches  ;  others  from  the  facial,  viz.,  the  superior  coronary  for  the 
gums  of  the  upper,  and  the  sub-mental  branches  for  those  of  the  lower  jaw ;  the  sub-lingual 
artery  also  supplies  the  latter.  The  veins  bear  the  same  name.  All  the  nerves  proceed 
from  the  fifth  pair,  viz.,  the  palatine  and  the  superior  and  inferior  dental  branches.  The 
naso-palatine  nerve  sends  ramifications  to  the  small  median  tubercle  upon  the  roof  of 
the  palate.     Few  parts  have  so  little  cellular  tissue  as  the  gums. 

Development. — According  to  the  best  authorities,  the  bony  and  membranous  portions 
of  the  hard  palate  are  developed  from  two  lateral  points,  which  unite  along  the  me- 
dian line,  so  that  the  malformation  known  by  the  name  of  harelip  with  cleft  palate,  is 
said  to  be  an  arrest  of  development.  The  fissure  may  be  either  single  or  double  in  front. 
If  the  cleft  be  double,  that  portion  of  the  upper  jaw  which  supports  the  incisor  teeth  is 
separated  on  both  sides  from  the  rest  of  the  bone.  Such  divisions  always  seem  to  me 
to  be  absolutely  departures  from  nature,*  for  at  no  period  of  its  growth  can  such  separa- 
tions or  clefts  be  detected  in  a  naturally-formed  foetus. 

Uses  of  the  Gums  and  Hard  Palate. — The  hard  palate  separates  the  buccal  cavity  from 
the  nasal  fossa.  It  serves  as  a  fulcrum  for  the  tongue  in  the  act  of  tasting,  in  mastica- 
tio'n,  deglutition,  and  the  articulation  of  sounds.  Before  the  eruption  of  the  teeth,  the 
gums  completely  close  the  alveoli,  and  serve  as  the  immediate  instruments  of  mastication ; 
and  they  become  hard,  and  supply  the  place  of  the  teeth  after  the  loss  of  those  organs. 
The  gums  have  great  influence  in  fixing  the  teeth  within  their  sockets,  and  hence  the 
loosening  of  the  former  from  scurvy  or  from  the  abuse  of  mercury.  We  may  consider  the 
gums  as  that  portion  of  the  mucous  membrane  in  which  the  dental  follicles  are  situated. 

The  Velum  Palati  and  Isthmus  Faucium. 

Dissection. — The  lower  surface  of  the  velum  palati  may  be  seen  by  forcibly  depressing 
the  lower  jaw,  or  still  better  by  sawing  it  across  in  the  median  line,  and  separating  the 
two  halves.  In  order  to  see  its  upper  surface,  the  pharynx  must  be  removed  entire,  and 
its  posterior  wall  divided  vertically  (as  in_^^.  141).  The  dissection  of  the  different  lay- 
ers which  enter  into  the  formation  of  the  velum  palati,  and  of  its  extrinsic  and  intrinsic 
muscles,  will  be  understood  from  the  following  descriptions  : 

External  Conformation. — The  velum  palati,  or  soft  palate  (c,  fig.  140),  is  a  muscular  and 
membranous  valve,  which  prolongs  the  palatine  arch  backward,  and,  therefore,  might  be 
called  the  membranous  palatine  arch.  It  is  a  sort  of  incomplete  septum  (septum  staphylin, 
Chauss.),  dividing  the  buccal  cavity  from  the  nasal  fossae  and  the  pharynx. 

Its  direction  is  curved :  its  upper  portion  is  horizontal,  but  it  soon  becomes  curved, 
and  passes  almost  directly  downward  (velum  pendulum  palati).  In  the  act  of  degluti- 
tion, the  velum  becomes  horizontal  during  the  passage  of  the  alimentary  mass,  but  im- 
mediately afterward  returns  to  its  oblique  and  pendulous  position,  and  thus  tends  to  pre- 
vent the  return  of  the  food  into  the  mouth.  In  several  pathological  conditions  the  velum 
is  thrown  backward  and  upward,  and  adheres  to  the  posterior  orifices  of  the  nasal  fossae. 
AH  these  changes  of  direction  affect  the  oblique,  and  not  the  horizontal  portion  of  the 
velum.  The  velum  palati  is  broad,  quadrilateral,  and  perfectly  symmetrical.  Its  in- 
ferior or  buccal  surface  is  concave,  and  continuous  with  the  hard  palate,  without  any  line 
of  demarcation.  This  surface  is  very  well  seen  when  the  mouth  is  opened,  and  is,  there- 
fore, easily  accessible  to  the  surgeon.  In  the  median  line  it  presents  a  white  raphe, 
which  is  a  continuation  of  the  median  raphe  of  the  hard  palate  ;  it  is  formed  by  a  small 
fibrous  cord,  causing  a  projection  under  the  mucous  membrane. 

The  superior  or  nasal  surface  of  the  velum  {fig.  141)  is  convex :  it  prolongs  the  floor 
of  the  nasal  fossae,  and,  from  its  obliquity,  directs  the  mucus  into  the  pharynx.  This 
surface  presents  a  median  projection  produced  above  by  the  palato-staphylin  muscles 
(azygos  uvulse,  a),  and  below  by  a  mass  of  glands.  Congenital  division  of  the  velum  is 
always  situated  in  the  median  line,  and  is  followed  by  so  great  a  retraction  of  its  two 
halves,  that,  in  some  cases,  the  entire  absence  of  the  velum  has  been  suspected. 

Its  upper  border  is  thick,  and  firmly  united  to  the  posterior  border  of  the  hard  palate. 

Its  lower  border  is  free,  extremely  thin  and  concave,  and  forms  the  upper  boundary  of 
the  isthmus  {t,fig.  141)  of  the  fauces  :  it  presents,  in  the  middle  line,  a  sort  of  appendix 
or  prolongation,  called  the  uvula  (u,fig.  140) :  this  is  of  a  conical  shape,  and  of  very  va- 
riable size  and  length ;  it  is  capable  of  considerable  elongation,  and  may  then  reach  the 
base  of  the  tongue,  but  not,  as  has  been  supposed,  the  upper  orifice  of  the  larynx.t  It 
is  not  very  uncommon  to  find  it  bifid,  and  sometimes  it  is  entirely  wanting. 

*  [/.  c,  not  mere  arrests  of  development.] 

+  In  consultation  upon  a  case  of  chronic  laryngitis,  I  was  much  surprised  to  hear  the  medical  attendant 
state  that  the  disease  was  the  result  of  irritation  produced  by  the  UTula  upon  the  superior  orifice  of  the  1* 
rfnx.     The  position  of  the  uvula  is  always  a  few  lines  in  advance  of  the  epiglottis. 


THE    VELUM    PALATI.  331 

The  two  lateral  borders  of  the  velum  limit  it  on  each  side,  and  separate  it  from  the 
cheek.  This  boundary  is  indicated  (on  each  side)  by  a  prominent  ridge  (before  /,  fi^. 
140),  extending  from  the  posterior  extremity  of  the  upper  to  the  corresponding  part  of 
the  lower  alveolar  border.  This  prominence  corresponds  to  the  anterior  margin  of  the 
internal  pterygoid  muscle,  and  is  formed,  in  a  great  measure,  by  a  series  of  small,  glan- 
dular structures,  which  are  collected  behind  the  last  great  molar  tooth  of  the  lower  jaw 
into  a  considerable  mass  resembling  a  small  gland. 

The  pillars  of  the  velum  palati.  These  are  two  lateral  columns  or  pillars,  having  an 
arched  form,  and  distinguished  into  anteriw  (behind  /,  fig.  140)  and  posterior  {g),  which 
pass  down  on  either  side  from  the  uvula.  Each  of  the  anterior  pillars  (the  two  forming 
together  the  anterior  arch  of  the  fauces)  proceeds  from  the  base  of  the  uvula  outward, 
and  then  vertically  downward,  describing  a  curve  with  its  concavity  directed  inward, 
and  terminates  at  the  sides  of  the  tongue,  opposite  the  anterior  extremities  of  the  V- 
shaped  series  of  papillae  vallatae  found  upon  that  organ.  Each  of  the  posterior  pillars 
(which  together  form  the  posterior  arch  of  the  fauces)  commences  at  the  apex  of  the 
uvula,  and  immediately  curves  into  an  arch,  having  a  smaller  diameter  than  that  repre- 
sented by  the  anterior  pillar,  and  then  passes  obliquely  downward,  backward,  and  out- 
ward, to  its  termination  on  the  sides  of  the  pharynx.  The  two  posterior  pillars  consti- 
tute the  free  margin  of  the  velum.  They  project  much  farther  inward  than  the  anterior 
pillars,  so  that  when  the  base  of  the  tongue  is  depressed  in  the  living  subject,  both  sets 
of  pillars  can  be  seen  at  the  same  time,  like  double  curtains,  placed  on  different  planes. 
Each  of  these  pillars  represents  a  triangle,  having  its  base  below  and  its  apex  above. 

ITie  Amygdaloid  Fossa. — From  the  direction  of  the  anterior  and  posterior  pillars,  they 
approach  each  other  above,  and  are  separated  by  a  considerable  interval  below.  This 
interval,  which  is  partly  occupied  by  the  tonsil  (w),  may  be  called  the  amygdaloid  excava- 
tion. In  order  to  have  a  good  idea  of  it,  it  is  necessary  to  make  a  vertical  section  of  the 
head  from  before  backward.  A  sort  of  recess  will  then  be  observed,  narrow  and  shallow 
above,  but  very  broad  and  deep  below,  especially  when  the  tonsil  (n)  is  small.  The  base 
of  this  fossa  corresponds  anteriorly  to  the  base  of  the  tongue  (J),  then  to  the  epiglottis 
(i),  the  larynx,  and  the  walls  of  the  pharynx :  the  bottom  of  the  fossa  corresponds  to  the 
angle  of  the  lower  jaw  and  the  lateral  portion  of  the  supra-hyoid  region,  where  it  is  sep- 
arated from  the  skin  only  by  a  thin  layer  of  soft  tissues.  The  dimensions  of  this  fossa 
always  remain  the  same  above,  but  are  very  variable  below,  according  as  the  tongue  is 
retained  in  the  mouth  or  protruded. 

The  Isthmus  Faucium. — The  posterior  orifice  of  the  buccal  cavity  is  called  the  isthmus 
faucium  (2,  figs.  140,  141).  It  is  a  sort  of  passage  between  the  buccal  and  the  pharyn- 
geal cavities,  bounded  below  by  the  base  of  the  tongue,  above  by  the  free  margin  of  the 
velum  palati,  divided  into  two  arches  by  the  uvula  in  the  middle,  and  the  two  pillars  on 
each  side.  This  posterior  orifice  of  the  mouth,  though  very  dilatable,  is  less  so  than  the  an- 
terior opening  of  the  same  cavity.  It  may  be  contracted,  and  even  completely  closed,  not 
only  from  inflammation  of  the  tonsils  and  arches  of  the  fauces,  but  also  from  the  contraction 
of  the  muscles  which  enter  into  the  formation  of  the  velum  and  its  pillars.  This  may  be 
seen  by  watching  the  movements  of  the  isthmus  of  the  fauces  in  a  person  who  will  sub- 
mit to  such  an  examination.  These  differences  in  the  dimensions  of  the  isthmus  are  con- 
cerned not  only  in  deglutition,  but  also  in  the  modulations  or  articulations  of  the  voice. 

Structure. — In  the  velum  palati  we  find  an  aponeurotic  framework  ;  also  certain  mus- 
cles by  which  it  is  moved,  which  are  either  extrinsic  or  intrinsic.  The  intrinsic  mus- 
cles are  those  constituting  the  azygos  uvulae,  viz.,  the  palato-staphylini ;  and  the  extrin- 
sic muscles  are  four  on  each  side,  two  descending,  viz.,  the  levator  palati,  and  the  cir- 
ciunflexus  or  tensor  palati,  and  two  ascending,  viz.,  the  palato-glossus,  and  the  palato- 
pharyngeus.  We  also  find  in  the  soft  palate  a  thick  layer  of  glands,  vessels,  nerves,  and 
cellular  tissue ;  and,  lastly,  a  covering  of  mucous  membrane. 

The  Aponeurotic  Portion. — The  aponeurotic  portion,  or,  rather,  the  principal  aponeuro- 
sis, is  extremely  dense,  and  continues  the  hard  palate  backward :  it  is  generally  regarded 
as  an  expansion  of  the  reflected  tendons  of  the  tensores  palati,  but  it  is,  in  a  great  measure, 
formed  of  proper  fibres  continuous  with  the  fibrous  tissue,  which  prolongs  backward  the 
septum  narium,  the  outer  borders  of  the  posterior  orifices  of  the  nasal  fossae,  and  the 
fibrous  portion  of  the  Eustachian  tube.  Below  this  aponeurotic  membrane  there  is  an- 
other fibrous  lamella,  continuous  with  the  fibrous  tissue  found  in  the  hard  palate.  The 
framework  of  the  upper  half  of  the  velum  palati  may,  therefore,  be  said  to  be  formed  of 
two  fibrous  layers,  one  superior,  the  other  inferior,  between  which  the  glandular  layer  is 
situated.  Lastly,  a  small  fibrous  band  extends  from  the  nasal  spine  to  the  uvula,  along 
the  median  raphe,  upon  the  lower  surface  of  the  velum,  producing  a  slight  elevation  of 
the  mucous  membrane.  This  little  band  sends  off  a  prolongation  between  the  glands  of 
the  velum,  which  separates  the  right  half  of  the  soft  palate  from  the  left. 

The  Muscles  of  the  Velum  Palati. 
Dissection. — This  is  common  to  all  the  muscles  of  the  soft  palate.   It  is  merely  neces- 
sary to  remove  the  mucous  membranes  and  the  subjacent  glands,  in  order  to  study  the 


SPLANCHNOLOGY. 

arrangement  of  these  muscles,  and  to  follow  the  ascending  and  descending  fibres  which 
emerge  from  or  enter  into  the  velum. 

The  Azygos  Uvidcs,  or  Palato-staphylini. 
The  palato-staphylini  (a,  fig.  141)  are  two  small,  fleshy,  cylindrical  bands  placed  in 
Fig.  14L  contact,  one  on  each  side  of  the  median  line,  and  extending 

from  the  posterior  nasal  spine,  or,  rather,  from  the  aponeuro- 
sis continuous  with  it,  to  the  base  of  the  uvula.  They  are 
covered  by  the  mucous  membrane  of  the  nose,  under  which 
they  form  a  projection,  and  they  cover  the  levatores  palati. 
The  two  muscles,  from  their  juxtaposition,  appear,  at  first 
sight,  to  form  a  single  rounded  muscle,  to  which  the  names 
azygos  uvulcz,  columellcB  musculus  teres,  have  been  given. 
Action. — To  raise  the  uvula. 


The  Levator  Palati,  or  Peristaphylinus  Internus. 

Dissection. — Remove  the  mucous  membrane  from  a  verti- 
cal ridge  which  exists  along  the  outer  border  of  the  posterior 
orifice  of  one  of  the  nasal  fossae,  behind  the  Eustachian  tube  ; 
then  remove  the  mucous  membrane  covering  the  upper  sur- 
face of  the  soft  palate. 

The  vertical  portion  of  the  levator  palati  (le  petro-salpin- 
go  staphylin,  Winslow ;  petro-staphylin,  Chauss.,  c,figs.  141, 
146)  is  situated  upon  the  outer  side  of  the  posterior  orifice  of  the  corresponding  nasal 
fossa  ;  its  horizontal  portion  is  in  the  substance  of  the  velum ;  it  is  thick,  narrow,  and 
rounded  above,  expanded  and  triangular  below.  It  arises  by  short  tendinous  fibres  from 
the  lower  surface  of  the  petrous  portion  of  the  temporal  bone,  near  its  apex,  and  from 
the  contiguous  part  of  the  cartilage  of  the  Eustachian  tube.  From  these  points  its  fibres 
pass  obliquely  downward  and  inward,  turning  round  the  outer  side  of  the  tube.  At  the 
outer  border  of  the  velum  palati  the  muscle  becomes  horizontal,  and  its  fasciculated  fibres 
diverge,  so  as  to  cover  the  whole  extent  of  the  antero-posterior  diameter  of  the  velum. 

The  anterior  fleshy  fasciculi  are  inserted  by  short  tendinous  fibres  into  the  posterior 
border  of  the  aponeurosis  of  the  soft  palate.  The  others  also  terminate  by  very  short 
tendinous  fibres,  which  are  blended  in  the  median  line  with  those  of  the  opposite  side, 
immediately  below  the  azygos  uvulae. 

Relations. — It  is  covered  by  the  mucous  membrane  of  the  pharynx  and  soft  palate  ;  its 
vertical  portion  is  in  relation,  on  the  outside,  with  the  circumflexus  palati  and  the  supe- 
rior constrictor  muscles,  and  its  horizontal  portion  with  the  palato-pharyngeus.  It  forms 
the  uppermost  muscular  layer  of  the  soft  palate. 

Action. — It  raises  the  velum  (elevator  palati  mollis,  Albin.,  Samm.).  The  length  of  its 
fibres,  its  direction,  and  its  shape,  render  it  well  fitted  for  this  purpose.  It  should  be  re- 
marked, that  the  tendinous  portion  of  the  velum  scarcely  participates  in  the  movement 
of  elevation. 

The  Circumflexus  or  Tensor  Palati,  or  the  Peristaphylinus  Externus. 

This  is  a  thin,  flat,  and  reflected  muscle  (le  pterygo  or  spheno  salpingo  staphylin, 
Winsl. ;  pterygo-staphylin,  Chauss.),  and  is  tendinous  for  a  considerable  part  of  its  ex- 
tent ;  its  vertical  portion  {d,  fig.  141,  146)  is  situated* along  the  internal  plate  of  the  ptery- 
goid process,  to  the  inner  side  of  the  internal  pterygoid  muscle  (b),  and  its  horizontal 
portion  {d)  in  the  substance  of  the  velum. 

Attachments. — It  arises  from  the  fossa  navicularis,  at  the  base  of  the  internal  pterygoid 
plate,  from  the  contiguous  part  of  the  great  wing  of  the  sphenoid,  and  from  a  small  por- 
tion of  the  cartilage  of  the  Eustachian  tube.  From  these  points  the  muscle,  which  forms 
a  thin  fasciculus,  flattened  at  the  side,  passes  vertically  downward :  near  the  hamular 
process  of  the  internal  pterygoid  plate  it  becomes  a  shining  tendon,  which  changes  its 
direction,  and  is  reflected  at  a  right  angle  under  that  process  :  it  is  retained  in  this  situ- 
ation by  a  small  ligament,  and  its  motions  are  facilitated  by  a  synovial  membrane.  The 
tendon  then  passes  horizontally  inward,  expands,  and  becomes  blended  with  the  aponeu- 
rotic membrane. 

Relations. — Its  vertical  portion  is  in  relation  on  the  outside  with  the  internal  pterygoid, 
and  on  the  inside  with  the  levator  palati,  from  which  it  is  separated  by  the  superior  con- 
strictor of  the  pharynx  (g,fig.  141)  and  by  the  internal  pterygoid  plate.  Its  horizontal 
or  aponeurotic  portion  is  anterior  to  the  levator  palati,  and  has  the  same  relation  as  thp 
aponeurotic  portion  of  the  velum. 

Action. — It  is  a  tensor  of  the  aponeurotic  portion  (tensor  palati),  but  does  not  otherwise 
move  the  velum.  As  Haller  has  remarked,  when  its  fixed  point  is  below,  it  can  dilate 
the  Eustachian  tube. 

The  Palato-pharyngeus,  or  Pharyngo-staphylinus. 
This  muscle  (thyro-staphylinus,  Douglas,  e  e,fig.  141)  is  narrow  and  fasciculated  in  the 


THE    PALATO-GLOSSUa.  333 

middle,  where  it  is  situated  in  the  posterior  pillar  of  the  fauces,  broad  and  membranous 
at  its  extremities,  one  of  which  is  in  the  velum  and  the  other  in  the  pharynx. 

Attachments. — It  arises  from  the  whole  extent  of  the  posterior  border  of  the  thyroid 
cartilage.  From  this  point  it  passes  vertically  upward,  and  forms  a  broad  and  thin  mus- 
cular layer,  the  fibres  of  which  are  first  collected  into  a  fasciculus  or  muscular  column, 
which  enters  the  posterior  pillar  of  the  fauces,  and  then,  again  expanding,  ocaipy  the 
whole  extent  of  the  antero-posterior  diameter  of  the  velum,  and  unite  in  the  median  line 
with  the  muscle  of  the  opposite  side,  so  as  to  form  an  arch.  The  anterior  fibres  are  in- 
serted into  the  posterior  border  of  the  aponeurosis  of  the  velum. 

RclatioTis. — It  forms  the  lowest  muscular  stratum  of  the  velum :  it  is  separated  from 
the  mucous  membrane  below  by  the  layer  of  glands :  it  is  in  relation  above  with  the 
muscular  layer  formed  by  the  expansion  of  the  levator  palati.  In  the  posterior  pillar  it 
is  in  relation  with  the  mucous  membrane,  which  covers  it  in  all  directions,  excepting  on 
the  outside.  In  the  pharynx  it  forms  the  innermost  muscular  layer,  i.  c.,  it  lies  between 
the  constrictors  and  the  mucous  membrane. 

Action. — The  two  palato-pharyngei  draw  the  velum  downward,  and  press  it  strongly 
against  the  alimentary  mass  during  deglutition  ;  they  therefore  form  a  constrictor  of  the 
isthmus  of  the  fauces.  When  they  take  their  fixed  points  above,  they  raise  the  poste- 
rior wall  of  the  pharynx.     They  are  important  agents  in  deglutition. 

The  Palato-glossus,  or  Olosso-staphylinus. 

This  is  a  small  fleshy  bundle  {o,jig.  141)  situated  in  the  anterior  pillar  of  the  fauces, 
narrow  in  the  middle,  and  broad  at  the  extremities.  Its  lower  extremity  is  expanded 
upon  the  side  of  the  tongue,  and  is  united  with  the  stylo-glossus.  Its  upper  extremity 
spreads  out  in  the  velum  palati,  and  becomes  blended  with  that  of  the  palato-pharyngeus. 
Its  middle  portion  is  very  slender ;  it  forms  the  anterior  pillar,  and  is  visible  through  the 
thin  mucous  membrane  by  which  it  is  covered. 

Action. — The  two  muscles  depress  the  velum  palati,  and  raise  the  edges  of  the  base 
of  the  tongue  ;  they  consequently  constrict  the  isthmus  faucium. 

The  Glandular  Layer  of  the  Velum  Palati. — Under  the  mucous  membrane  covering  the 
upper  surface  of  the  velum  palati,  there  are  some  scattered  glands,  M'hich  are  more  nu- 
merous on  the  sides  than  along  the  middle  ;  but  on  the  lower  surface  of  the  velum  there 
is  a  much  more  obvious  collection  of  glands,  particularly  dense,  opposite  the  aponeurotic 
portion  of  the  velum,  and  forming  a  contiouation  of  the  glandular  layer  of  the  hard  pal- 
ate. Similar  glands  are  found  in  the  uvula,  the  size,  and,  in  some  measure,  the  form  of 
which  they  determine.  These  small  glands  in  the  velum  exactly  resemble  the  salivary 
glands  already  described  as  existing  in  the  lips,  the  cheeks,  and  the  roof  of  the  palate. 

The  Mucous  Membrane. — Both  surfaces  of  the  velum  are  covered  by  mucous  mem- 
brane, which  constitutes,  as  it  were,  its  integuments.  These  two  mucous  layers  are 
remarkable,  inasmuch  as  each  presents  the  peculiar  characters  of  the  cavity  to  which  it 
belongs.  Thus,  the  lower  layer  preserves  the  characters  of  the  buccal  mucous  mem- 
brane, and  the  upper  layer  those  of  the  nasal.*  The  two  layers  are  continuous  with 
each  other  along  the  free  margin  of  the  velum  palati ;  the  fold  of  mucous  membrane 
forming  this  margin  passes  beyond'  the  other  constituent  tissues,  so  that,  for  the  space 
of  half  a  line  or  a  hne,  the  two  mucous  layers  are  in  contact.  The  same  occurs  in  the 
uvula,  the  apex,  and  sometimes  the  lower  half  of  which  consists  of  a  duplicature  of  mu- 
cous membrane,  containing  some  loose  cellular  tissue,  which  is  very  susceptible  of  infil- 
tration. Either  serous  or  sanguineous  infiltration  of  the  uvula  produces  an  elongation  of 
this  part,  called  relaxation  of  the  uvula.  I  should  not  omit  to  mention  the  great  differ- 
ence, in  regard  to  sensibility  and  liability  to  inflammation,  that  exists  between  the  mu- 
cous membrane  of  the  free  and  adherent  borders  of  the  velum  palati. 

Vessels  and  Nerves. — These  are  very  numerous  in  proportion  to  the  size  of  the  part. 
The  arteries  arise  from  the  palatine  and  the  superior  and  in/erior  pharyngeal.  The  veins 
are  similarly  named,  and  follow  the  same  course.  The  lymphatic  vessels,  which  have 
been  little  studied,  enter  the  lymphatic  glands  at  the  angle  of  the  jaw.  The  nerves  are 
derived  from  the  palatine  branches  given  off  by  Meckel's  ganglion,  and  from  the  glosso 
pharyngeus. 

Development. — ^We  have  here  again  the  question,  whether  the  velum  is  formed  origi- 
nally from  two  halves,  which  afterward  become  united  in  the  median  line  ;  in  favour  of 
this  view  we  may  adduce  those  cases  in  which  the  uvula  and  the  velum  are  bifid,  either 
with  or  without  fissure  of  the  hard  palate  and  lip.  In  the  youngest  embryos  which  I 
have  examined,  I  have  always  found  the  velum  undivided. 

Uses. — The  velum  palati  is  a  contractile  valve,  which  fulfils  very  important  functions 
in  deglutition,  in  the  utterance  of  articulate  sounds,  and  in  the  modulation  of  the  voice  ; 
it  is  capable  of  being  elevated  and  depressed    Elevation  affects  its  muscular,  but  not  its 

*  [According  to  the  recent  researches  of  Dr.  IIenl6,  the  ciliated  cohimnar  epithelium  (like  that  of  the  nasal 
mucous  membrane)  is  found  upon  the  upper  surface  of  the  velum,  only  in  the  neighbourhood  of,  and  a  short 
distance  below,  the  expanded  orifice  of  the  Eustachian  tube  ;  the  remaininsr  portion  of  the  upper  surface,  as 
well  as  the  free  border,  and  the  whole  of  the  lower  surface,  are  covered  with  the  squamous  epithelium,  simi 
lar  to  that  of  the  buccal  mucous  membrane.] 


334  SPLANCHNOLOGY. 

aponeurotic  portion :  this  movement  cannot  be  carried  so  far  as  to  revert  the  velum  up- 
ward. Depression  may  be  carried  to  such  an  extent  as  to  close  the  isthmus  faucium  by 
the  approximation  of  the  velum  and  the  base  of  the  tongue.  The  contraction  of  the  pa- 
lato-pharyngei,  which  are  curved  muscles,  may  be  so  complete  as  to  bring  the  posterior 
pillars  of  the  fauces  into  contact,  and  thus  close  the  isthmus  in  a  transverse  direction. 
The  uvula  moves  independently  of  the  velum.  When  the  aponeurosis  of  the  velum  pa- 
lati  is  rendered  tense,  the  velum  itself  is  enabled  to  resist  both  elevation  and  depression. 

The  Tonsils,  or  Amygdal.*:. 

The  terms  amygdala.  (ufivySaMa,  an  almond),  or  tonsils,  are  applied  to  a  group  of  mu- 
cous follicles  (n,  fig.  140)  which  occupy  the  interval  between  the  pillars  of  the  fauces  on 
each  side.  They  are  placed  there  on  account  of  the  necessity  of  lubricating  the  isthmus 
during  the  passage  of  the  alimentary  mass.  Their  form  pretty  nearly  resembles  that  of 
an  almond  ;  they  are  directed  obliquely  downward  and  forward,  and  their  size  is  exceed- 
ingly subject  to  either  congenital  or  accidental  variation.  In  some  subjects  they  can 
scarcely  be  said  to  exist ;  in  others  they  fill  up  the  whole  amygdaloid  fossa,  and  project 
more  or  less  into  the  isthmus  of  the  fauces,  so  as  to  impede  deglutition,  o^  fcv^en  respiration. 

The  compound  tonsil  results  from  its  component  follicles  being  collected  into  several 
distinct  masses. 

The  internal  surface  is  free,  and  may  be  seen  when  the  base  of  the  tongue  is  depress- 
ed ;  it  is  perforated  by  foramina,  like  the  ligneous  shell  of  an  almond.  These  foramina, 
which  vary  in  number  and  size,  have  been  frequently  mistaken  for  syphilitic  ulcerations. 
They  lead  into  small  cells,  in  which  mucus  sometimes  collects,  and  is  then  ejected  in 
hard  fetid  lumps,  which  have  been  erroneously  supposed  to  be  pulmonary  tubercles.  Its 
external  surface  is  covered  immediately  by  the  aponeurosis  of  the  pharynx,*  and  then  by 
the  superior  constrictor. 

The  tonsil  corresponds  to  the  angle  of  the  lower  jaw.  Compression  behind  this  an- 
gle, therefore,  affects  it  at  once,  and  causes  pain  in  cases  where  it  is  inflamed.  It  has  an 
important  relation  with  the  internal  carotid  artery,  especially  when  that  vessel,  descri- 
bing a  curve  with  the  convexity  directed  inward,  touches  the  tonsil.  In  front  the  tonsil 
is  in  relation  with  the  anterior  pillar  of  the  fauces,  and,  therefore,  with  the  palato-glossus 
muscle  ;  behind,  with  the  posterior  pillar,  and,  accordingly,  with  the  palato-pharyngeus 
muscle. 

Structure. — In  structure  the  tonsils  are  intermediate  between  mucous  follicles  and 
glands  ;  they  consist  of  an  agglomeration  of  follicles,  continuous  with  those  at  the  base 
ot  the  tongue.  Groups  of  these  follicles  open  into  small  cells  or  lacunae,  which  again 
open  upon  the  internal  surface  of  the  tonsil  by  the  foramina  already  described.  The 
mucous  membrane  covers  the  inner  surface  of  the  tonsil,  and,  penetrating  through  the 
foramina,  lines  the  interior  of  all  the  cells. 

The  arteries  are  very  large,  considering  the  size  of  the  organ.  They  are  derived  from 
the  labial,  the  inferior  pharyngeal,  the  lingual,  and  the  superior  and  inferior  palatine. 
The  veins  form  a  plexus  round  this  organ,  called  the  tonsillar  plexus  ;  it  is  a  dependance 
of  the  pharyngeal  plexus.  The  lymphatic  vessels  terminate  in  the  glands  found  near  the 
angle  of  the  jaw ;  hence  the  inflammation  or  enlargement  of  those  glands  in  conse- 
quence of  inflammation  of  the  tonsil.  The  lingual  and  glosso-pharyngeal  nerves  form  a 
plexus  outside  the  tonsil,  which  gives  off  some  branches  to  it. 

The  Tongue. 

The  tongue,  the  principal  organ  of  taste,  is  situated  within  the  buccal  cavity,  and,  con- 
sequently, at  the  commencement  of  the  digestive  passages  (J,  fig.  140)  behind  the  lips, 
which  in  many  animals  are  organs  of  prehension  ;  also  behind  the  teeth,  the  organs  of 
mastication,  and  below  the  organ  of  smell,  which  possesses  the  sense  of  taste  in  the 
lower  tribes,  and  is  necessary  in  all  animals  for  the  perception  of  flavours.  It  is  a  mus- 
cular organ,  free  and  movable  above,  before,  and  on  the  sides.  It  is  retained  in  its  po- 
sition by  ligaments  which  attach  it  to  the  os  hyoides  ;  and,  by  muscles  connecting  it  to 
the  same  bone,  to  the  styloid  processes  and  to  the  lower  jaw ;  so  that  it  appears  to  me 
anatomically  impossible  for  persons  to  have  been  destroyed  by  swallowing  their  tongues, 
as  some  historians  have  related.  Nor  do  I  believe,  notwithstanding  the  authority  of  J 
L.  Petit,  that  division  of  the  fraenum  in  infants  may  be  followed  by  a  similar  accident. 

The  size  of  the  tongue,  though  variable  in  different  individuals,  is  always  proportional 
to  the  curve  described  by  the  lower  jaw ;  it  is  not  large  enough  to  fill  the  buccal  cavity 
completely  when  the  jaws  are  closed.  It  has  not  been  satisfactorily  proved  that  too 
large  a  tongue  is  the  cause  of  certain  defects  in  speech.  However,  a  natural  size  is  not 
absolutely  necessary  for  the  exercise  of  its  functions,  for  these  are  performed  even  when 
considerable  portions  have  been  removed  from  its  apex  and  sides. 

Direction. — Its  anterior  portion  is  horizorttal ;  behind,  it  slopes  downward  and  back- 
ward, and  curves  abruptly,  so  as  to  become  vertical  and  reach  the  os  hyoides,  which  in 
some  measure  constitutes  its  base.     This  direction,  which  is  maintained  so  long  as  the 

♦  The  existence  of  this  aponeurosis  explains  why  the  tonsil  always  becomes  enlarged  internally,  and  also 
why  abscesses  of  this  part  never  open  externally. 


THE    TONGUE. 


335 


tongue  is  within  the  mouth,  is  somewhat  altered  when  it  is  protruded,  the  tongue  then 
becoming  horizontal,  and  the  os  hyoides  raised. 

Figure. — Examined  without  any  anatomical  preparation,  the  tongue  appears  of  an  oval 
figure,  having  its  great  end  behind.  Its  form  is  determined,  and,  as  it  were,  measured, 
by  the  parabolic  curve  of  the  lower  jaw,  by  which  it  is  circumscribed.  When  separated 
from  the  neighbouring  parts,  it  represents  an  ellipse,  with  its  long  diameter  from  before 
backward.  It  is  perfectly  symmetrical,  flattened  above  and  below,  narrow  and  thin  in 
front,  and  increasing  in  thickness  and  in  breadth  from  before  backward.  Its  figure, 
which  has  itself  become  a  term  of  comparison,  does  not  appear  to  be  essential  for  the 
articulation  of  sounds,  a  function  that  would  at  first  appear  to  be  peculiarly  connected 
with  this  form. 

The  tongue  presents  for  our  consideration  an  upper  and  a 
lower  surface,  two  edges,  a  base,  and  an  apex. 

The  Upper  Surface  or  Dorsum  of  the  Tongue.  —  This  is  free 
in  the  whole  of  its  extent,  corresponds  to  the  roof  of  the  pal- 
ate, and  is  divided  into  two  lateral  halves  by  a  median  furrow, 
which  often  limits  the  progress  of  disease.  It  is  covered  by 
innumerable  eminences,  which  render  it  very  rough  ;  these 
should  be  distinguished  into  such  as  are  perforated,  viz.,  the 
glandular  eminences,  and  such  as  are  entire,  and  have  no  ori- 
fice, viz.,  the  papilla  {papilla,  a  nipple). 

The  perforated  eminences,  or  lingual  glands,  improperly  class- 
ed among  the  papillae,  and  known  under  different  names,,  may 
be  distinguished  by  their  circular  openings,  which  are  perfect-  ,| 
ly  visible  to  the  naked  eye  ;  by  their  being  situated  only  at  the 
base  of  the  tongue  ;  by  their  rounded  form,  and  their  having 
no  pedicle  ;  by  the  arrangement  of  the  mucous  membrane, 
which  passes  over  without  adhering  to  them  ;*  and,  lastly,  by 
dissection,  which  most  distinctly  reveals  their  glandular  na- 
ture. These  lingual  glands,  moreover,  are  not  follicles,  but 
true  glandular  organs,  analogous  to  the  labial  and  buccal 
glands.  They  form  a  V-shaped  ridge,  strongly  marked  in 
some  subjects,  and  bounded  in  front  by  the  ridge  (a  a,  fig. 
142)  of  the  same  shape,  formed  by  the  caliciform  papillae. 

All  the  other  eminences  of  the  tongue  are  papillae,  which  we  may  describe  as  the  large 
and  the  small. 

The  large  papillce  are  called  caliciform :  they  are  arranged  in  two  lines  (a  a,  fig.  142), 
united  like  the  limbs  of  a  V,  open  in  front.  Their  number  varies  from  sixteen  to  twen- 
ty, some  of  which  are  placed  irregularly.  Haller  has  seen  them  forming  two  rows  on 
each  side.  Their  size  is  also  variable,  but  they  are  larger  than  all  the  other  papillae. 
Each  papilla  forms  a  truncated  and  inverted  cone,  the  base  of  which  is  free,  and  the 
truncated  apex  adherent  (papillae  truncate,  Haller ;  papilles  boutonnees  ou  a  tete,  Boyer). 
They  are  placed  in  a  sort  of  calyx  or  cup,  or  surrounded  by  a  circular  trench  :  hence  the 
name  of  papillae  circumvallatae  (papilles  cahciformes,  Cuvier).  The  border  or  rim  of  this 
cup  is  itself  a  circular  papilla,  t 

At  the  angle  of  union  of  the  two  rows  of  these  glands  is  a  blind  opening  (b),  which  is 
frequently  wanting,  and  generally  known  as  the  foramen  caecum  of  Morgagni  (lacune  de 
la  langue,  Chaussier).  Several  anatomists  of  the  last  century  affirmed  that  certain  sup- 
posed salivary  ducts,  which  were  afterward  shown  to  be  merely  veins,  had  their  termi- 
nation in  this  foramen ;  it  is  now  generally  considered  to  be  a  cul-de-sac  for  the  recep- 
tion of  the  secretion  from  several  follicles ;  but  it  appears  to  me  to  be  only  the  cavity 
of  a  calyx,  the  papilla  corresponding  to  which  is  very  imperfectly  developed.  When  the 
papilla  is  more  developed,  or  the  calyx  less  deep  than  usual,  the  foramen  caecum  is  said 
to  be  wanting. 

The  Smull  Papilla. — These  occupy  all  that  part  of  the  dorsal  surface  of  the  tongue 
which  is  in  front  of  the  V-shaped  ridge,  formed  by  the  papilla  circumvallatae  ;  they  pre- 
sent many  varieties.  Some  of  them  are  conical,  others  filiform ;  some  are  pointed  like 
a  reed,  and  others  are  lenticular  or  fungiform,  that  is,  flattened  at  the  top,  and  supported 
by  a  narrow  pedicle  ;  but  the  conical  or  filiform  are  evidently  the  most  numerous,  for 
they  occupy  of  themselves  the  anterior  portion  and  the  apex  of  the  tongue,  while  all  the 
other  varieties  are  disseminated  between  them.     They  are  directed  obliquely  backward, 

*  ll.  e.,  without  being  closely  united  to  their  outer  surface,  as  it  is  to  that  of  the  papillse.  The  mucous 
membrane,  as  in  all  glands,  is  really  prolonged  into  their  interior.] 

t  The  want  of  a  uniform  nomenclature  for  the  papilla:  of  the  tongue  has  occasioned  great  obscurity.  I  do 
not  know  two  authors  who  agree  in  this  respect.  M.  Boyer  calls  the  lingual  glands  papilles  lenticulaires  ;  the 
caliciform  papillse,  papilles  boutonnees  ou  a  tile  ;  and  applies  the  term  papilles  coniques  to  the  papillse  generally 
known  by  that  name.  Gavard  called  the  glands  papilles  muqueuses  ;  and  the  caliciform  p.ipillffl,  papilles  fungi- 
formes.  M.  H.  Cloquet  appears  to  have  confounded  both  the  glands  and  the  caliciform  papilla;  under  the  name 
of  papilles  lenticulaires ;  the  papilles  fungiformes,  according  to  him,  are  irregularly  disseminated  over  the  edges 
and  apex  cfthe  tongue.     The  use  cif  tile  tenn  conical  papillse  is  the  only  point  in  which  they  are  all  agreed. 


4 


SPLANCHNOLOGY. 

SO  that,  by  rubbing  the  tongue  sUghtly  from  behind  forward,  they  may  be  brushed  up, 
and  their  exact  sliape  and  length  ascertained.  This  oblique  direction  is  much  more 
marked  in  the  lower  animals  than  in  man. 

The  conical  papillae  are  sometimes  arranged  in  regular  or  irregular  lines,  so  as  to  give 
the  tongue  a  fissured  appearance.  Sometimes  even  several  papillae  are  united  in  a  line, 
so  as  to  form  a  jagged  ridge.  We  may  add,  that  there  is  very  great  variety  both  in  the 
shape  and  arrangement  of  the  lingual  papillae.* 

The  lower  surface  of  the  tongue  is  free  only  in  its  anterior  third,  the  muscles  which  con- 
nect the  tongue  to  the  neighbouring  parts  being  attached  to  the  posterior  two  thirds.  On 
the  free  portion,  which  we  shall  alone  notice  here,  is  observed  a  median  furrow,  more 
distinct  than  that  on  the  upper  surface.  At  the  posterior  part  of  this  furrow  is  a  fold  of 
mucous  membrane,  called  the  franum  lingua,  which  is  sometimes  prolonged  to  the  apex 
of  the  tongue,  and  prevents  the  movements  of  that  organ,  both  in  the  act  of  sucking  and 
during  articulation  :  hence  the  necessity  for  the  operation  known  as  the  division  of  the 
fracnum.  On  each  side  of  this  furrow  are  seen  the  ranine  veins,  on  which  the  ancients 
performed  venesection  ;  also  an  antero-posterior  projection  formed  by  the  lingual  muscle. 

The  edges  of  the  tongue  are  thick  behind  and  thinner  towards  the  point.  The  papiUae 
are  prolonged  in  a  regular  manner  upon  their  upper  half  in  a  series  of  vertical  and  par- 
allel lines. 

The  actual  base  is  fixed  to  the  os  hyoides :  the  apparent  base,  which  is  seen  at  the 
back  of  the  dorsal  surface,  presents  three  glosso-epiglottid  folds,  of  which  the  median 
(above  b,fig.  142)  is  much  larger  than  the  other  two. 

The  apex  is  situated  immediately  behind  the  incisor  teeth ;  the  median  furrows  of  both 
surfaces  are  prolonged  upon  it. 

Having  thus  examined  the  peculiarities  offered  by  the  external  surface  of  the  tongue 
without  the  aid  of  dissection,  we  shall  now  examine  its  structure. 

Structure  of  the  Tongue. — The  tongue  being  the  organ  of  one  of  the  senses,  and  being, 
also,  capable  of  various  movements,  we  must  examine  its  structure  with  reference  to 
both  these  objects.  But,  after  the  example  of  Haller,+  we  shall  be  principally  occupied 
here  with  its  structure  as  a  movable  organ. 

The  tongue  is  essentially  composed  of  muscular  fibres,  and,  in  this  respect,  the  heart 
is  the  only  organ  which  can  be  compared  to  it.  Its  framework  consists  of  the  os  hy- 
oides, of  a  median  cartilaginous  lamina,  and  of  its  papillary  membrane. 

Framework  of  the  Tongue. — The  os  hyoides,  already  described  (seen  in^^.  143),  is  tru- 
ly the  bone  of  the  tongue  :  hence  it  has  been  called  the  lingual  bone  by  some  anatomists. 
In  man  it  is  not  prolonged  by  a  process  into  the  substance  of  the  tongue,  as  in  the  lower 
animals,  but  is  united  to  it  by  the  hyo-glossal  membrane,  which  commences  at  the  pos- 
terior lip  of  the  body  of  this  bone  ;  and,  again,  since  the  os  hyoides  is  united  to  the  thy- 
roid cartilage  {t)  by  ligaments,  it  follows  that  all  the  movements  of  this  bone  are  commu- 
nicated both  to  the  tongue  and  to  the  larynx,  between  which  parts  it  is  situated.  From 
the  middle  of  this  fibrous  membrane,  the  median  cartilaginous  lamina  of  the  tongue,  de- 
scribed by  M.  Blandin,  proceeds.  This  lamina,  which  is  perfectly  distinct  from  the  car- 
tilage described  by  M.  JBaur  in  the  dog  and  the  wolf,t  is  situated  in  the  median  line  ;  it 
is  directed  vertically,  and  gives  attachment  to  some  muscular  fibres  by  its  two  lateral 
surfaces  ;  its  upper  edge  is  thin,  and  reaches  the  middle  of  the  dorsal  region  of  the  tongue  , 
its  lower  edge  is  seen  between  the  genio-hyo-glossi,  where  it  is  either  free  or  covered 
by  a  few  muscular  fibres  which  interlace  below  it.  It  is  thick  behind,  but  thin  in  front, 
where  its  fibres  have  a  number  of  intervals  between  them,  like  those  in  the  septum  of 
the  corpora  cavernosa  penis. 

I  regard  the  papillary  membrane  as  part  of  the  framework  of  the  tongue,  on  account  of 
Its  density,  which  is  so  great  that  it  is  with  difficulty  cut  by  the  scalpel.  Moreover,  a 
great  number  of  the  muscular  fibres  terminate  in  it. 

The  Muscles  of  the  Tongue. 

These  are  either  intrinsic  or  extrinsic. 

The  Intrinsic  Muscles. — The  ancients  regarded  the  tongue  as  a  single  muscle,  t*" 
structure  of  which  they  did  not  attempt  to  unravel.  Columbus  was  the  first  to  conside? 
this  organ  as  composed  of  two  juxtaposed  muscles.  If  the  texture  of  the  tongue  be  ex- 
amined by  means  of  sections  made  in  different  directions,  it  will  be  found  to  be  compo- 
sed of  an  interlacement  of  muscular  fibres,  which  will,  indeed,  appear  to  be  inextricable. 
Among  these  different  sections,  I  would  principally  call  attention  to  a  vertical  section, 
made  at  right  angles  to  the  axis  of  the  tongue.    This  section  presents  a  pale  muscular 

*  [All  these  kinds  of  papillae  are  extensions  of  the  mucous  membrane,  and  are,  therefore,  composed  of  simi- 
lar elements.  The  papillae  vallatae  contain  many  loops  of  vessels,  the  papillae  conicae,  in  general,  only  a  few ; 
all  are  abundantly  supplied  with  nerves.] 

t  Hallcr  treats  of  the  muscles  of  the  tongue  when  describing  the  organ  of  voice  (lib.  ix.,  sect,  ii.,  p.  421), 
and  of  the  papillary  membrane  with  the  organs  of  the  senses  (lib.  xiii.,  sect.  ).,  p.  99). 

t  Ihe  cartilage  described  by  Baur  is  a  fibrous  cord,  subjacent  to  the  mucous  membrane,  and  occnpying  the 
median  line  on  the  lower  surface  of  the  tongue.  It  extends  from  the  apex  of  the  latter,  where  it  is  very  wel 
marked,  to  \Ui:  l^ise.  where  it  terminates  in  a  cellular  rapht. 


THE    MUSCLES    OF    THE   TONGUE.  337 

tissue  in  the  centre,  in  which  successive  layers  of  vertical  and  transverse  fibres  may  be 
distinguished.  A  soft,  fatty  substance,  the  lingual  adipose  tissue,  is  interposed  between 
these  muscular  fibres  ;  it  is  analogous  to  the  fat  formed  at  the  base,  or,  sometimes,  among 
the  fibres  of  the  ventricles  of  the  heart ;  it  increases  in  quantity  towards  the  base  of  the 
tongue,  but  is  entirely  wanting  at  the  apex.  Around  this  central  part  of  the  tongue, 
whicli  may  with  propriety  be  called,  after  M.  Baur,  the  lingual  nucleus  (noyau  lingual),  we 
find  a  very  thin  layer  of  red  fibres  situated  above,  a  somewhat  thicker  layer  on  each  side, 
and  a  much  thicker  layer  below  ;  the  lateral  and  inferior  layers  belong  to  the  extrinsic 
muscles. 

A  transverse  vertical  section,  therefore,  demonstrates  the  presence  of  vertical  and  trans- 
verse fibres  in  the  tongue  :  an  antero-posterior  vertical  section  shows  that  there  are  fibres 
running  from  one  end  of  the  organ  to  the  other,  and  will  also  display  the  vertical  fibres 
already  mentioned.  Thus,  by  means  of  simple  sections,  we  can  demonstrate  the  exist- 
ence of  longitudinal  fibres  running  from  the  base  to  the  apex  of  the  tongue  ;  of  vertical 
fibres  passing  from  the  upper  to  the  lower  suarface ;  and  of  transverse  fibres  extending 
from  one  side  to  the  other ;  and  other  dissections  will  confirm  this  statement.  Though 
Malpighi,*  in  a  memoir  of  great  interest,  had  very  exactly  described  and  figured  the  ar- 
rangement of  the  three  orders  of  fibres  in  the  tongue  of  the  calf ;  though  Steven  proved 
their  existence  in  the  human  tongue,  and  Bidloo  had  carried  his  observations  still  far- 
ther ;  and  although  Massa  had  recommended  that,  to  facilitate  this  investigation,  the 
tongue  should  be  previously  boiled,  or  should  be  examined  after  putrefaction  had  com- 
menced ;  still,  almost  all  anatomists,  including  Haller,  neglected  this  subject,  until  MM. 
Baur,  Gerdy,  and  Blandin  directed  attention  to  it  almost  at  the  same  time.  From  the 
examination  of  the  boiled  tongues  of  the  ox,  the  sheep,  and  man,  I  have  observed  the 
following  facts : 

1.  Under  the  papillary  membrane,  which,  as  I  have  said  before,  has  almost  the  density 
of  cartilage,  there  is  a  series  of  fibres  running  from  before  backward.  These  fibres  ap- 
pear to  rise  in  succession  from  the  papiUary  membrane,  and  form  a  layer,  which  is  thicker 
in  front,  where  the  fibres  are  collected  into  a  small  space,  than  it  is  behind,  where  they  are 
scattered  and  pale.  In  the  ox  they  traverse  the  yellowish  glandular-looking  substance 
found  at  the  base  of  the  tongue.  This  thin  layer  is  described  by  Malpighi,  and  has  been 
called  the  superior  or  superficial  lingualis  muscle. 

2.  On  the  lower  surface  of  the  tongue,  between  the  genio-hyo-glossus  and  the  hyo- 
glossus,  we  find  a  longitudinal  bundle,  reaching  from  the  base  to  the  apex.  This  thick 
bundle  was  first  described  by  Douglas  under  the  name  of  the  lingualis  muscle ;  it  might  be 
called  the  inferior  lingualis.  The  lingual  muscle  of  authors  generallyt  is  a  small  mus- 
cular fasciculus,  situated  on  the  lower  surface  of  the  tongue,  between  the  stylo-glossus 
(m,  fig.  143)  and  the  genio-hyo-glossus  (a).  It  arises  from  the  base  of  the  tongue,  in  an 
indistinct  manner,  amid  an  intricate  mass  of  muscular  fibres ;  from  thence  it  passes  for- 
ward, and  terminates  at  the  apex  of  the  tongue,  where  it  unites  with  the  fibres  of  the 
stylo-glossus.     It  shortens  the  tongue,  and  depresses  its  point. 

3.  On  either  side  of  the  tongue  we  find  two  layers  of  oblique  and  very  thin  fibres,  cross- 
ing each  other.  The  superficial  layer  consists  of  fibres  passing  forward  and  downward, 
the  deep  layer  of  fibres  running  obliquely  forward  and  upward.  These  two  layers  can 
only  be  seen  towards  the  base.  They  are  more  easily  shown  in  the  ox  than  in  man. 
We  also  find  along  each  side  some  antero-posterior  fibres,  continuous  both  with  the  stylo- 
glossus and  the  palato-glossus. 

4.  Lastly,  the  dissection  of  the  lingual  nucleus  of  a  boiled  tongue  enables  us  most  dis- 
tinctly to  separate  the  vertical  and  transverse  fibres  already  noticed  as  being  seen  in  the 
different  sections  of  the  tongue.  The  transverse  fibres  form  a  slight  concavity  above  : 
the  vertical  fibres  converge  a  little  from  above  downward.  In  the  substance  of  the  lin- 
gual nucleus,  near  the  base  of  the  tongue,  a  soft,  liquid,  adipose  Fig.  143. 
matter  is  interposed  between  the  muscular  fibres. 

The  Extrinsic  Muscles. — The  extrinsic  muscles  are  three  on 
each  side,  viz.,  the  stylo-glossus,  the  hyo-glossus,  and  the  genio- 
hyo-glossus. 

The  Stylo-glossus. 
The  stylo-glossus  {u,figs.  114, 143,  146)  is  a  small,  slender  mus- 
cle, cylindrical  above,  thin,  triangular,  and  bifid  below.  It  arises 
from  the  styloid  process  by  some  tendinous  fibres  surrounding  the 
lower  half  of  that  process,  and  slightly  also  from  the  stylo-maxil- 
lary ligament.  The  fleshy  fibres  proceeding  from  these  points 
form  a  rounded  fasciculus,  which  passes  downward,  inward,  and 
forward.  At  the  margin  of  the  tongue,  opposite  the  anterior  pillar 
of  the  fauces,  the  muscle  becomes  flattened,  expanded,  and  trian- 

*  It  is  notunwoithy  of  notice,  that  Malpighi  commenced  upon  the  tongue  that  series  of  researches  into  the 
structure  of  organs  which  has  made  him,  as  it  were,  the  founder  of  textural  anatomy. 

t  [From  this  statement  Albinus  must  be  excepted  ;  the  lingualis  of  that  anatomist  corresponds  exactly  witb- 
Sie  muscle  described  by  Douglas.] 

Ua 


338  SPLANCHNOLOGY. 

gular,  and  divides  into  two  parts :  one  external,  which  runs  along  the  corresponding 
margin  of  the  tongue,  from  the  base  to  the  apex  ;  the  other  internal,  which  passes  be- 
tween the  two  portions  of  the  hyo-glossus,  assumes  a  transverse  direction,  and  is  blend- 
ed with  the  transverse  fibres  of  the  tongue. 

Relations. — On  the  outside  it  is  in  relation,  successively,  with  the  parotid  gland,  the  in- 
ternal pterygoid  muscle,  the  sub-lingual  gland,  the  lingual  branch  of  the  fifth  nerve,  and 
the  mucous  membrane  of  the  tongue.  On  the  inside  it  has  relations  with  the  stylo- 
hyoid ligament,  the  tonsil,  the  superior  constrictor  of  the  pharynx,  and  the  hyo-glossus 
muscle. 

Action. — ^The  stylo-glossus  draws  the  corresponding  edge  of  the  tongue,  and,  conse- 
quently, the  entire  organ,  upward,  and  to  its  own  side.  When  the  two  stylo-glossi  act 
together,  the  tongue  is  increased  in  breadth,  and  carried  upward  and  backward :  it  there- 
fore assists  in  retraction  of  the  tongue. 

The  Hyo-glossus. 

This  is  a  thin,  quadrilateral  muscle  {t,figs.  113,  114,  146),  arising  from  the  os  hyoides 
by  two  very  distinct  origins  :  one  from  the  body  of  the  bone,  near  the  great  cornu ;  the 
other  from  the  whole  extent  of  the  anterior  border  of  the  great  cornu,  and  also  from  its 
point. 

From  this  double  origin  the  fleshy  fibres  pass  upward  parallel  to  each  other,  forming 
a  quadrilateral  muscle,  which  expands  a  little,  in  order  to  terminate  upon  the  sides  of  the 
tongue,  between  the  stylo-glossus  and  the  lingualis.  There  is  an  evident  continuity  be- 
tween this  muscle  and  the  vertical  fasciculi  of  the  tongue. 

The  direction  of  this  muscle  varies  according  to  the  positions  of  the  tongue.  It  is 
vertical  when  the  organ  is  contained  in  the  buccal  cavity,  and  is  directed  obliquely  up- 
ward and  forward  when  the  tongue  is  protruded. 

The  hyo-glossus  is  almost  always  divided  into  two  portions  corresponding  to  its  double 
origin,  which  are  separated  below  by  a  cellular  interval,  and  above  by  the  posterior  fas- 
ciculus of  the  stylo-glossus.  Albinus  described  them  as  two  distinct  muscles  :  the  por- 
tion arising  from  the  body  of  the  os  hyoides,  as  the  hasio-glossus ;  and  under  the  name  of 
the  cerato-glossus,  the  portion  arising  from  the  great  cornu.  He  also  admitted  a  third 
portion,  under  the  name  of  the  chondro-glossus,  described  as  proceeding  from  the  small 
cornu.  Haller,  who  considered  this  latter  fasciculus  a  distinct  muscle,  states  that  he  has 
always  been  able  to  find  it. 

Relations. — On  the  outside  it  is  in  relation  with  the  stylo-glossus,  the  mylo-hyoideus, 
the  digastricus,  the  sub-lingual  gland,  the  hypo-glossal  nerve,  and  lingual  branch  of  the 
fifth.  On  the  inside,  it  corresponds  to  the  lingual  artery,  which  never  passes  between 
the  two  portions  of  the  muscle,  to  the  genio-hyo-glossus,  and  to  the  middle  constrictor  of 
the  pharynx. 

Action. — It  depresses  the  corresponding  edge  of  the  tongue,  and  draws  it  towards  the 
OS  hyoides.  When  the  tongue  has  been  protruded  from  the  mouth,  it  assists  in  drawing 
it  backward.  When  the  two  muscles  act  together,  the  tongue  is  depressed  and  con- 
tracted in  its  transverse  diameter. 

The  Genio-hyo-glossus. 

This  is  the  largest  of  the  extrinsic  muscles  of  the  tongue :  it  is  thick,  triangular,  and, 
as  it  were,  radiated  {a,  Jig.  143).  It  arises  from  the  superior  genial  process  of  the  infe- 
rior maxilla  by  a  sort  of  tendinous  tuft,  from  which  the  fleshy  fibres  immediately  proceed 
as  from  a  centre,  radiating  backward  in  different  directions.  The  posterior  fibres  are 
attached  to  the  os  hyoides,  either  directly  or  through  the  medium  of  a  membrane.  They 
constitute  the  superior  genio-hyoideus  of  Ferrein.  The  more  anterior  fibres  expand  upon 
the  sides  of  the  pharynx,  occupy  the  interval  between  the  os  hyoides  and  the  stylo-glos- 
sus, and  immediately  cover  the  corresponding  portion  of  the  pharynx,  or,  rather,  the 
amygdaloid  excavation.  These  fibres,  which  are  very  distinct  (I  was  acquainted  with 
them  before  I  was  aware  that  they  had  been  described  by  others),  constitute  the  genio- 
pharyngiens  of  Winslow.  The  fibres  which  are  next  in  order,  proceeding  forward,  all 
belong  to  the  tongue,  and  traverse  the  whole  length  of  that  organ.  The  most  anterior 
fibres,  which  are  the  shortest  of  all,  having  reached  the  lower  surface  of  the  tongue, 
curve  forward,  and  terminate  near  its  point.  All  the  others  pass  perpendicularly  upward 
and  turn  a  little  outward,  so  as  to  terminate  in  the  papillary  mucous  membrane  at  the 
side  of  the  median  line. 

Relations. — On  the  inside  it  corresponds  to  its  fellow,  being  separated  from  it  by  cel- 
lular tissue  frequently  loaded  with  fat.  The  two  muscles  are  perfectly  distinct,  and  sep- 
arable until  they  enter  the  substance  of  the  tongue,  beyond  which  point  they  cannot  be 
separated  from  each  other.  On  the  outside  it  is  in  relation  with  the  sub-lingual  gland, 
the  mylo-hyoideus,  hyo-glossus,  stylo-glossus,  and  lingualis  muscle.  The  hypo-glossal 
nerve  perforates  this  muscle  between  its  genio-pharyngeal  and  lingual  portions.  Its 
lower  margin  corresponds  to  the  genio-hyoideus,  from  which  it  is  separated  by  a  very 
delicate  layer  of  cellular  tissue.  Its  upper  margin  is  subjacent  to  the  mucous  membrane, 
of  which  it  occasions  a  prominence  on  each  side  of  the  fraenum. 


THE    MUSCLES    OF    THE    TONGUE.  339 

Action. — By  its  hyoid  fibres  it  raises  the  os  hyoides  and  carries  it  forward ;  by  it:. 
pharyngeal  fibres  it  draws  the  pharynx  forward  and  compresses  its  sides  ;  by  its  poste- 
rior lingual  fibres,  as  well  as  the  hyoid,  it  carries  the  base  of  the  tongue,  and,  conse- 
quently, the  whole  organ,  forward.  This  is  the  muscle  by  which  we  are  enabled  to  pro- 
trude the  tongue  from  the  mouth.  By  means  of  its  anterior  or  reflected  fibres,  the  tongue, 
when  protruded,  is  drawn  back  into  the  mouth  ;  lastly,  by  its  median  lingual  fibres,  the 
tongue  is  made  into  a  groove  ;  when  one  muscle  acts  alone,  it  is  protruded  to  the  oppo- 
site side. 

Such,  including  the  palato-glossus,  already  described,  are  the  extrinsic  muscles  of  the 
tongue :  I  shall  not  include  among  them  the  mylo-glossus  of  the  older  anatomists,  and 
described,  also,  by  Heister  and  Winslow,  because  it  appears  to  be  nothing  more  than 
that  portion  of  the  superior  constrictor  of  the  pharynx  which  is  inserted  into  the  mylo- 
hyoid ridge  ;  nor  yet  the  glosso-epiglottideus,  a  very  large  muscle  existing  in  the  lower 
animals,  which  has  been  described  by  Albinus  in  the  human  subject  as  a  dependance  of 
the  genio-hyo-glossus.  After  the  most  careful  examinations,  I  have  never  been  able  to 
meet  with  it. 

Vessels,  Nerves,  and  Cellular  Tissue. — The  cellular  tissue  of  the  tongue  receives  arter- 
ies and  veins,  and  from  it  issue  both  veins  and  lymphatics. 

The  arteries  consist  of  the  proper  lingual,  which  are  very  large  in  comparison  to  the 
size  of  the  organ,  the  palatine,  and  the  inferior  pharyngeal. 

The  veins  form  two  sets,  as  in  the  limbs,  and  for  the  same  reason :  a  superficial  set, 
independent  of  the  arteries ;  and  a  deep  set,  accompanying  those  vessels. 
^  The  lymphatics  enter  the  deep  lymphatic  glands  of  the  supra-hyoid  region. 

The  nerves  are  very  large,  and  are  derived  from  three  sources,  viz.,  from  the  ninth 
pair,  or  hypo-glossal ;  from  the  lingual  branch  of  the  fifth  pair ;  and  from  the  glosso-pha- 
ryngeal  division  of  the  eighth  pair.* 

The  cellular  tissue  of  the  tongue  is  partly  serous  and  partly  adipose  ;  the  serous  por- 
tion is  chiefly  situated  in  front,  the  other  is  more  abundant  behind. 

The  Tegumentary  Membrane  and  Glands. — ^The  tegumentary  membrane  of  the  tongue  is 
a  continuation  of  the  mucous  membrane  of  the  mouth.  It  is  thin  and  slightly  adherent 
in  almost  all  its  non-papillary  portion,  and  becomes  very  thick  and  strongly  adherent 
wherever  the  papillae  exist.  The  edges  of  the  tongue  are  occupied  by  numerous  small 
glands,  continuous  with  the  sub-lingual  glands,  and  opening  upon  the  lower  wall  of  the 
mouth  by  small  excretory  ducts. 

Development. — The  tongue  is  visible  in  the  youngest  embryos.  Its  early  development 
has  reference  to  its  functions,  for  it  is  an  essential  agent  in  suction,  and  is,  consequently, 
brought  into  use  immediately  after  birth.  The  tongue  is  not  double  or  bifid  at  first ;  in 
the  earliest  embryos  it  presents  the  appearance  of  a  single  tubercle. 

Uses  of  the  Tongue. — The  tongue  has  two  very  distinct  uses.  It  is  the  organ  of  taste, 
and  it  is  also  a  movable  organ.  In  this  place  we  shall  consider  it  in  the  latter  capacity 
only.  The  movements  of  the  tongue  are  concerned  in  the  prehension  of  food,  in  suction, 
in  mastication,  in  tasting,  in  deglutition,  in  articulation,  and  in  playing  upon  wind- 
instnmients. 

In  order  to  fulfil  such  a  variety  of  uses,  it  is  organized  so  as  to  be  capable  of  moving 
in  every  direction.  Its  movements  are  either  extrinsic  or  intrinsic.  The  extrinsic  move- 
ments, or  those  of  the  whole  tongue,  may  be  ascertained  from  our  knowledge  of  the  sin- 
gle or  combined  actions  of  its  extrinsic  muscles.  Thus,  it  may  be  protruded  from  the 
mouth,  drawn  back  into  that  cavity,  inclined  to  the  right  or  to  the  left  side,  directed  up- 
ward or  downward,  or  carried  into  any  intermediate  position.  In  its  intrinsic  move- 
ments it  may  be  contracted  transversely  by  the  transverse  fibres,  diminished  in  length 
by  its  longitudinal  fibres,  and  contracted  vertically  and  rendered  concave  by  its  vertical 
fibres ;  lastly,  its  apex  can  be  carried  upward  by  the  superior,  and  downward  by  the 
inferior  longitudinal  fibres. 

By  far  the  most  varied,  precise,  and  rapid  motions  of  this  organ  are  required  in  the  ar- 
ticulation of  sounds,  in  which  it  is  one  of  the  chief  agents.  In  consequence  of  this  use, 
which  is  by  no  means  the  result  of  a  special  conformation  (for,  by  constant  practice,  an- 
imals, whose  tongues  are  very  different  from  ours,  may  be  taught  to  articulate),  the 
tongue  is  associated  with,  and  becomes  one  of  the  principjd  instruments  of  the  mind.  It 
is  the  organ  by  which  thought  is  most  conamonly  expressed.  This  use  is  peculiar  to 
man. 

*  The  ninth  nerve  is  distributed  to  the  muscles,  the  lingual  nerve  to  the  mucous  membrane  of  the  anterior 
part  and  sides,  and  the  glosso-pharyngeal  to  that  of  the  base  of  the  tongue.     (See  Organ  of  Taste.) 

I  have  lately  seen  a  considerable  branch  of  the  facial  nerve  terminating  in  the  tongue  ;  it  was  given  oft 
from  the  facial  nerve  at  its  exit  from  the  stylo-mastoid  foramen,  crossed  obliquely  in  front  of  the  styloid  pro- 
cess with  which  it  was  in  contact,  passed  in  front  of  the  stylo-pharyngeus  muscle  externally  to  the  tonsil  and 
parallel  to  the  glosso-pharyngeal  nerve,  which  was  situated  behind  it,  communicated  with  that  nerve  by  sev- 
eral arches,  and  divided  into  two  branches  at  the  base  of  the  tongue,  one  of  which  ran  along  the  edge  or  that 
organ,  and  the  other  anastomosed  by  a  loop  with  the  glosso-pharyngeal :  from  this  loop  some  filaments  passed 
off,  to  be  distributed  in  the  usual  manner. 

The  opposite  side  did  not  exhibit  a  corresponding  arrangement. 


SPLANCHNOLOGY. 

.  .  -    .ziki...  -  The  Salivary  Glands. 

Besides  the  labial,  buccal,  and  palatine  glands  found  in  the  cavity  of  the  mouth,  which, 
by  most  anatomists,  have  been  confounded  with  the  follicles  or  muciparous  crypts,  there 
exists  around  this  cavity  a  particular  glandular  apparatus,  forming  a  sort  of  chain  or  col- 
lar, symmetrically  extended  along  the  rami  and  body  of  the  lower  jaw.  This  chain  is 
interrupted  so  as  to  form  six  glandular  masses,  three  on  each  side,  named,  from  their  sit- 
uation, the  parotid,  sub-maxillary,  and  sub-lingual  glands.* 

The  Parotid  Gland. 

The  parotid  gland  {p,  fig.  144),  so  called  from  being  situated  below  and  in  front  of 
Fig.  144.  the  external  auditory  meatus  {napa,  near,  ovc,  wrof,  the 

ear),  fills  the  parotid  excavation.  It  is  bounded  in  front 
by  the  posterior  edge  of  the  ramus  of  the  lower  jaw  ; 
behind,  by  the  external  auditory  meatus  and  the  mas- 
toid process  ;  above,  by  the  zygomatic  arch ;  below,  by 
the  angle  of  the  lower  jaw  ;  and  on  the  inside,  by  the 
styloid  process  and  the  muscles  which  proceed  from 
it.  This  gland  has  given  its  name  to  the  region  occu- 
pied by  it. 

It  is  the  largest  of  all  the  salivary  glands,  and  even 
exceeds  all  the  rest  put  together.  Its  form  is  irregular, 
and  is  determined  by  that  of  the  surrounding  parts,  upon 
which  it  is  moulded  like  a  piece  of  soft  wax.  Its  su- 
perficial portion  is  broad,  but  it  suddenly  becomes  con- 
tracted when  it  dips  behind  the  ramus  of  the  jaw. 

In  order  to  obtain  a  good  idea  of  the  size  and  shape 
of  this  gland,  it  must  be  removed  entire  from  the  irreg- 
ular mould  in  which  it  is  lodged.   It  has  been  compared 
to  a  pjTamid,  of  which  the  base  is  directed  outward,  and  the  apex  inward. 

Relations. — Its  external  surface,  or  base,  is  broad,  oblong  from  above  downward,  irreg 
tilarly  quadrilateral,  and  lobulated  at  the  edges ;  it  is  sub-cutaneous,  being  separated  from 
the  skin,  however,  by  the  parotid  fascia  and  the  risorius  of  Santorini,  when  that  muscle 
exists.  + 

Its  anterior  surface  is  grooved  so  as  to  embrace  the  posterior  edge  of  the  ramus  of  the  low- 
er jaw.  A  bursa,  or  some  loose  cellular  tissue,  facilitates  the  movements  of  these  parts. 
This  surface  is  also  in  relation  with  the  internal  pterygoid  muscle,  the  stylo-maxillary 
ligament,  and  the  masseter  muscle,  on  the  external  surface  of  which  it  is  prolonged  to  a 
greater  or  less  extent  (see  fig.  144)  in  different  individuals,  and  is  separated  from  it  an- 
teriorly by  the  ramifications  of  the  facial  nerve,  by  some  loose  cellular  tissue,  and  by  the 
transverse  artery  of  the  face. 

Its  posterior  surface  is  in  relation  %vith  the  cartilaginous  portion  of  the  external  audito 
ry  canal,  being  moulded  upon  its  convexity,  and  adhering  to  it  by  very  dense  cellular 
tissue  :  it  corresponds  also  to  the  mastoid  process,  the  stemo-cleido-mastoid  and  digas- 
tric muscles,  and  indirectly  to  the  transverse  process  of  the  atlas.  This  surface  is  ex 
tremely  irregular,  adheres  by  means  of  dense  cellular  tissue,  and  is  dissected  off  with 
great  diflieulty  in  an  attempt  to  remove  the  entire  gland. 

On  the  inside  it  is  reduced  to  a  mere  border,  which  corresponds  to  the  styloid  process, 
and  the  muscles  and  ligament  connected  with  it.  It  sends  off  a  considerable  prolonga- 
tion into  the  space  which  separates  the  styloid  process  and  its  muscles  from  the  inter- 
nal pterygoid  :  but  the  most  important  relation  of  this  border  is  with  the  external  carot- 
id artery,  for  which  it  furnishes  a  groove,  and  sometimes,  even,  a  complete  canal. 

Its  upper  extremity  corresponds  to  the  zygomatic  arch  and  the  temporo-maxillary  ar- 
ticulation. 

Its  lower  extremity  fills  up  the  interval  between  the  angle  of  the  jaw  and  the  sterno- 
mastoid,  and  is  separated  from  the  sub-maxillary  gland  (m)  by  a  very  thick  fibrous  septum. 
Besides  the  relations  already  indicated,  the  parotid  has  others  with  the  vessels  and 
nerves  which  traverse  it  at  different  depths  :  these  may  be  called  its  intrinsic  or  deep  re- 
lations. Thus,  the  external  carotid  artery  almost  always  perforates  the  gland  near  its  in- 
ner side  ;  the  temporal  artery  {see  fig.  144),  the  transversalis  faciei,  and  the  anterior  au- 
ricular, which  commence  in  the  substance  of  the  gland,  also  traverse  it  in  various  direc- 
tions. We  also  find  within  it  the  temporal  vein,  which  is  a  communicating  branch  be- 
tween the  external  and  internal  jugulars  ;  the  trunk  of  the  facial  nerve  is  at  first  placed 
behind  the  gland,  then  penetrates  it,  and  divides  into  two  or  three  branches,  which  again 
subdivide  and  traverse  it  in  all  directions.     The  auricular  nerve,  a  branch  of  the  cervi 

*  The  continuity  of  this  glandular  chain,  admitted  by  some  anatomists,  is  only  apparent.  A  fibrous  septum 
always  intervenes  between  the  sub-maxillary  and  the  parotid  glands. 

t  In  a  female  in  whom  I  dissected  the  parotid  gland,  the  risorius  arose  from  the  superior  semicircular 
line  of  the  occipital  bone  by  two  distinct  fasciculi,  which,  passing  downward  and  forward,  united  opposite  the 
apex  of  the  mastoid  process,  and  then  proceeding  horizontally,  expanded  upon  the  parotid  gland.  Some  of  the 
fibres  reached  the  commissure  of  the  lips,  but  the  greater  number  were  lost  upon  the  parotid  fascia. 


THE    PAROTID  GLAND.  341 

cal  plexus,  also  passes  through  it  very  superficially.*  The  parotid  gland,  by  a  remark- 
able exception,  always  contains  in  its  substance,  a  little  below  the  surface,  several  lym- 
phatic glands,  which  may  be  readily  distinguished  by  their  red  colour  from  the  proper 
tissue  of  the  gland.  It  may  be  imagined  that  a  morbid  development  of  these  glands  may 
have  often  been  mistaken  for  disease  of  the  parotid  itself 

Structure. — A  thick  fibrous  membrane  covers  the  parotid  glands,  and  sends  prolonga- 
tions into  it  which  divide  it  into  lobes,  and  these,  again,  into  glandular  lobules.  The  ac- 
tual structure  of  the  gland,  therefore,  depends  upon  the  nature  of  these  lobules ;  and, 
without  entering  into  details  which  belong  more  properly  to  general  anatomy,  it  may  be 
stated  that  it  has  been  shown,  by  the  aid  of  the  simple  microscope,  that  each  lobule  is  a 
porous,  spongy  body,  something  like  the  pith  of  the  rush,  and  provided  with  afferent  ves- 
sels, viz.,  the  arteries ;  and  efferent  vessels,  i.  e.,  the  veins  and  excretory  ducts.^  The  re- 
lations of  the  nerves  and  lymphatic  vessels  with  these  granules  have  not  been  accurate- 
ly determined. 

The  parotid  arteries  are  very  numerous  ;  some  of  them  arise  directly  from  the  exter- 
nal carotid ;  others  from  its  branches,  more  particularly  from  the  superficial  temporal, 
the  transversalis  faciei,  and  the  anterior  and  posterior  auricular. 

The  veins  have  similar  names,  and  follow  the  same  direction  as  the  arteries.  There 
is  a  parotid  venous  plexus. 

The  lymphatic  vessels  are  little  known  :  they  terminate  partly  in  the  glands  at  the  an- 
gle of  the  jaw,  and  partly  in  those  which  lie  in  front  of  the  auditory  meatus.  I  have 
already  said  that  one  or  more  lymphatic  glands  are  always  situated  in  the  parotid  gland, 
a  few  hues  below  its  surface. 

The  nerves  are  derived  from  the  anterior  auricular  (a  branch  of  the  cervical  plexus) 
and  from  the  facial  nerve :  they  seem  to  be  lost  in  the  substance  of  the  gland. 

The  Parotid  Duct. — A  small  excretory  duct  (resulting  from  the  union  of  its  terminating 
vesicles)  proceeds  from  each  lobule,  and  unites  almost  immediately,  at  a  very  acute  an- 
gle, with  the  ducts  of  the  adjacent  lobules.  From  the  successive  union  of  all  these  ducts 
a  single  canal  results,  which  emerges  from  about  the  middle  of  the  anterior  margin  of 
the  gland :  this  is  the  parotid  duct  (s,  fig.  144),  called  also  the  du^t  of  Steno,  although  it  had 
been  previously  described  by  Casserius.  It  passes  horizontally  forward,  about  five  or 
six  lines  beneath  the  zygomatic  arch,  across  the  masseter,  and  at  right  angles  to  its 
fibres.  At  the  anterior  border  of  the  masseter  it  changes  its  direction,  curves  in  front 
of  a  mass  of  fat  situated  there,  dips  perpendicularly  into  the  fat  of  the  cheek,  perforates 
the  buccinator  in  the  same  direction,  and  glides  obhquely,  for  the  space  of  several  lines, 
between  that  muscle  and  the  mucous  membrane  of  the  mouth,  which  it  pierces  opposite 
the  intervEd  between  the  first  and  the  second  upper  great  molar  teeth,  almost  on  a  level 
with  the  middle  of  their  crown. 

The  mode  in  which  the  Stenonian  duct  opens  into  the  buccal  cavity  does  not  appear 
to  me  to  have  been  sufficiently  well  understood.  It  exactly  resembles  the  manner  in 
which  the  ureters  enter  the  bladder.  Thus,  it  glides  obliquely  for  a  certain  distance  be- 
neath the  mucous  membrane,  a  fact  that  may  be  easily  determined  by  perforating  the 
cheek  at  the  point  where  the  duct  passes  through  the  buccinator,  and  then  measuring 
the  interval  between  this  perforation  and  the  buccal  orifice  of  the  canal :  this  interval 
varies  from  two  to  three  lines  in  extent.  Again,  the  buccal  orifice  is  oblique,  like  the 
vesical  opening  of  the  ureter,  so  that  it  is  extremely  easy  to  pass  a  fine  probe  into  it. 

The  duct  of  Steno  is  often  accompanied  by  an  accessory  glandt  (glandula  socia  paroti- 
dis,  see  fig.  144),  situated  between  it  and  the  zygomatic  arch.  The  duct  of  this  little 
gland  opens  into  the  main  canal.  I  have  seen  two  small  accessory  glands  situated  above 
the  canal,  one  at  the  middle  and  the  other  at  the  anterior  part  of  the  masseter.  Lastly, 
as  the  parotid  duct  is  passing  through  the  buccinator,  it  is  surrounded  by  a  series  of 
glands  continuous  with  those  of  the  cheeks,  called  molar  glands,  the  ducts  of  some  of 
which  appear  to  open  into  the  canal,  and  those  of  others  directly  into  the  mouth.  Al- 
though it  is  not  flexuous,  the  canal,  when  separated  from  the  surrounding  parts,  will  be 
found  much  longer  than  it  appears  at  first  sight. 

Fig.  145. 

*  These  relations  prove  the  almost  absolute  impossibility  of  extirpating  this  gland 
by  a  cutting  instrument,  and  of  compression  after  Desault's  method,  for  the  cure 
of  salivary  fistulae.  Compression,  which  is  extremely  painful,  on  acxjount  of  the 
number  of  nerves  passing  through  it,  can  only  affect  its  superficial  portion. 

t  [Weber  has  succeeded  in  distending  with  mercury  the  ducts  {d,fig.  145)  of  the 
parotid  gland  in  the  infant,  and  has  shown  that  they  terminate  in  closed  vesicular 
extremities  (c)  about  -  A  ^j  of  an  inch  in  diameter,  three  times  that  of  the  capillary 
vessels  ramifying  upon  them.  See  Mullet's  Physiology,  translated  by  Baly,  p.  447  ; 
and  MuIUt  on  the  Glands,  translated  by  Solly,  p.  69.— (Tr.) 

In  the  early  embryo  of  the  sheep,  this  gland  consists  of  a  canal  which  opens  into 
the  mouth  by  one  extremity,  but  is  closed  at  the  other,  and  has  numerous  short 
hollow  branches  projecting  from  it  into  a  granular  blastema  :  as  development  ad- 
vances, the  blastema  is  absorbed,  and  the  ramified  canal,  increasing  in  length,  be- 
comes iitill  more  ramified,  so  as  to  form  the  ducts  with  their  closed  vesicular  termi- 
nations.] *  Magnified  fifty  timcf. 

t  Desault  found  this  gland  very  large  in  a  subject  where  the  corresponding  parotid  was  atropmed. 


m 


SPLANCHNOLOGY. 


Relations. — The  Stenonian  duct  is  sub-cutaneous  and  superficial  where  it  passes  orer 
the  masseter  ;  it  is  protected  by  a  large  quantity  of  fat,  and,  in  front  of  the  maisseter,  by 
the  zygomaticus  major.  A  considerable  branch  of  the  facial  nerve,  and  some  arteries 
derived  from  the  transversalis  faciei,  run  along  this  canal. 

Structure. — An  exaggerated  idea  is  generally  entertained  of  the  thickness  of  the  duct 
of  Steno ;  it  is  only  thick  at  its  anterior  part,  where  it  is  strengthene(^  by  an  expansion 
of  the  aponeurosis  of  the  buccinator  muscle.  When  freed  from  the  surrounding  fat,  it 
is  not  thicker  than  most  other  ducts,  the  ureters,  for  example.  The  notion  that  it  is  in- 
extensible  is  also  incorrect.  It  is  true,  however,  that  the  diameter  of  its  canal  is  not 
in  proportion  to  the  size  of  the  gland.  It  is  formed  by  two  membranes  :  one  external, 
the  nature  of  which  is  not  well  known ;  the  other  internal,  consisting  of  a  prolongation 
of  the  mucous  membrane  of  the  mouth.     Its  arteries  and  veins  are  very  large. 

The  Sub-maxillary  Gland. 

The  sub-maxillary  gland  {m,fig.  144)  is  situated  in  the  supra-hyoid  region,  and  part- 
ly behind  the  body  of  the  lower  jaw  ;  it  is  bounded  by  the  reflected  tendon  of  the  digas- 
tricus,  below  which  it  ahnost  always  projects. 

Size  and  Figure. — It  is  much  smaller  than  the  parotid,  but  larger  than  the  sub-lingual. 
It  is  oblong  from  before  backward,  elliptical,  irregular,  and  divided  into  two  or  three 
lobes  by  some  deep  fissures. 

Relati(ms. — On  the  outside  and  below,  it  corresponds  to  a  depression  on  the  inferior 
maxillary  bone,  in  which  it  is  completely  lodged  when  the  jaw  is  depressed.  When, 
on  the  other  hand,  the  head  is  bent  backward  upon  the  neck,  the  gland  appears  almost 
entirely  in  the  supra-hyoid  region,  and  is  in  relation  with  the  platysma,  being  separated 
from  it  by  the  cervical  fascia,  to  which  it  is  united  by  cellular  tissue  of  so  loose  a  tex- 
ture, that  it  may  be  called  a  synovial  bursa.  This  surface  of  the  gland  is  also  in  rela- 
tion with  the  internal  pterygoid  muscle  and  the  numerous  lymphatic  glands  situated 
£dong  the  base  of  the  jaw.  On  the  inside  and  above,  it  corresponds  to  the  digastric,  my- 
lo-hyoid,  and  hyo-glossus  muscles,  and  to  the  hypo-glossal  and  lingual  nerves. 

The  sub-maxillary  gland  almost  always  forms  a  prolongation  of  variable  size  and  shape 
above  the  mylo-hyoideus.  Sometimes  the  lobules  of  which  it  is  composed  are  situated 
in  lines,  so  as  to  appear  like  the  Whartonian  duct,  or,  rather,  a  second  canal  running 
parallel  to  it.  Most  commonly,  this  prolongation  is  of  considerable  size  and  irregular, 
and  forms,  as  it  were,  a  second  sub-maxillary  gland. 

The  most  important  relation  of  the  gland  is  to  the  facial  artery  (a),  which  runs  in  a 
groove  on  its  posterior  border,  and  upon  the  contiguous  part  of  its  external  surface. 
Sometimes  this  groove  is  prolonged  forward,  and  divides  the  gland  into  two  unequal 
parts.  We  cannot  avoid  seeing  the  great  analogy  between  this  arrangement  and  that 
of  the  external  carotid  artery,  with  regard  to  the  parotid  gland. 

Structure. — This  is  identical  with  that  of  the  parotid.  Its  investing  fibrous  membrane 
is  weaker,  and  stiU  more  diflicult  of  demonstration.  The  arteries  are  numerous,  and 
arise  from  the  facial  and  the  lingual.  The  veins  correspond  to  them.  The  b/mpkatic 
vessels  are  little  knovra,  and  enter  the  neighbouring  glands.  The  nerves  are  derived 
from  the  lingual  and  the  myloid  branch  of  the  dental.  I  should  remark,  that  all  the  nerves 
proceeding  from  the  sub-maxillary  ganglion  are  destined  for  this  gland. 

The  excretory  duct  of  the  sub-maxillary  gland  is  called  the  Whartonian  duct,  although 
it  was  really  discovered  by  Van  Home.  It  is  formed  by  the  successive  union  of  all  the 
small  ducts  proceeding  from  the  lobules ;  it  leaves  the  gland  at  the  upper  bifurcation  of 
its  anterior  extremity,  and,  consequently,  above  the  mylo-hyoideus,  and  is  directed  ob- 
liquely upward  and  inward,  parallel  to  the  great  hypo-glossaJ  and  lingual  nerves.  It  is 
at  first  placed  between  the  mylo-hyoid  and  hyo-glossus  muscles,  and  then  ghdes  between 
the  genio-hyo-glossus  and  the  sub-hngud  gland,  to  the  inner  surface  of  which  it  is  at- 
tached.* I  have  never  succeeded  in  determining  whether  it  receives  any  excretory 
duct  or  ducts  from  this  gland.  Having  reached  the  side  of  the  fraenum  linguae,  the  duct, 
which  is  sub-mucous  in  the  whole  of  the  portion  corresponding  to  the  sub-lingual  gland, 
changes  its  direction,  passes  forward,  and  opens  by  an  extremely  narrow  orifice  upon 
the  simimit  of  a  prominent  and  movable  papilla  found  behind  the  incisor  teeth.  This 
orifice,  which  can  scarcely  be  seen  by  the  naked  eye,  was  found  to  admit  a  hog's  bristle 
in  a  particular  case  presented  to  the  Anatomical  Society  by  M.  Robert.t  Bordeu  has 
correctly  described  the  appearance  of  this  orifice  by  the  term  ostiolum  umbilicale. 

The  duct  of  Wharton  is  remarkable  for  the  thinness  of  its  coats,  which  are  not  thick- 
er than  those  of  a  vein ;  for  its  great  calibre,  which  exceeds  that  of  Steno's  duct ;  for 
the  extensibility  of  its  coats,  the  canal  sometimes  acquiring  an  enormous  size  ;  and,  last- 
ly, for  its  proximity  to  the  mucous  membrane  of  the  mouth,  which  causes  it,  when  much 
dilated,  to  project  into  the  buccal  cavity. 

*  [See_^^.  146,  in  which  the  gland  itself  (m)  hangs  down,  jesting  upon  the  hyo-glossus  ;  the  digastric  and 
mylo-hyoid  muscles  and  half  the  lower  jaw  have  been  removed.] 

t  This  was  observed  in  a  shoemaker  ;  the  bristle  had  become  the  nucleus  of  a  salivary  calculus. 


THE   SUB-LINGUAL   GLAND.  343 

..-.^^..,       .;   ^^^^i  .  The  Sub-lingual  Gland. 

The  sub-lingual  gland  {I,  fig.  146),  which  may  be  regarded  as  an  agglomeration  of  small- 
.  cr  glands  analogous  to  those  of  the  lips  and  palate,  is  sit- 
.  uated  in  the  sub-lingual  fossa  of  the  lower  jaw,  at  the  side  J^g.  146^ 

,  of  the  symphysis  menti :  it  is  much  smaller  than  the  pre- 
ceding gland,  with  which  it  is  sometimes  continuous.  Its 
shape  8  oblong,  like  that  of  an  olive  flattened  at  the  sides. 
The  following  are  its  relations :  It  is  subjacent  to  the 
mucous  membrane,  beneath  which  its  upper  edge  forms 
j^a  prominent  ridge,  running  from  before  backward  along 
,the  sides  of  the  fraenum  ;  its  lower  edge  rests  upon  the 
mylo-hyoid  muscle  ;  its  external  surface  corresponds 
partly  to  the  mucous  membrane  and  partly  to  the  sub-lin- 
gued  fossa ;  its  internal  surface  is  in  relation  with  the 
mucous  membrane,  with  the  genio-hyo-glossus  (from 
which  it  is  separated  by  the  lingual  nerve),  with  the  Whar- 
tonian  duct  (which,  we  have  seen,  closely  adheres  to  it), 
and  with  the  ranine  vein.  Its  anterior  extremity  touches 
the  gland  of  the  opposite  side.  Its  posterior  extremity  and  its  lower  edge  are  embraced 
by  the  lingual  nerve,  which  gives  numerous  filaments  to  it.  A  small  glandular  prolonga- 
tion also  proceeds  from  its  posterior  extremity,  and  runs  along  the  edge  of  the  tongue. 

Structure. — Precisely  similar  to  that  of  the  other  salivary  glands.  Its  arteries  arise 
.from  the  sub-mental  and  sub-lingual.  Its  veins  bear  the  same  name.  Its  nerves  are 
niunerous,  and  are  derived  from  the  lingual. 

Its  excretory  ducts,  called  also  the  ducts  of  Rivinus,  from  their  discoverer,  are  seven 
or  eight  in  number.  They  open  along  the  sub-lingual  crest :  their  orifices  may  be  shown 
by  placing  a  coloured  fluid  in  the  mouth.  Most  anatomists  state,  that  several  of  the 
ducts  of  this  gland  open  into  the  Whartonian  duct. 

General  Characters  of  the  Salivary  Glands. — The  salivary  glands  present  the  following 
general  characters : 

1.  They  are  situated  around  the  lower  jaw,  extending  along  its  body  and  rami,  from 
the  condyles  to  the  symphysis  ;  they  are  in  relation,  on  the  one  hand,  with  the  maxilla- 
ry bone,  and  on  the  other  with  numerous  muscles,  so  that  they  are  subjected  to  consid- 
erable compression  during  the  movements  of  the  lower  jaw.  2.  They  all  have  direct 
relations  with  large  arteries,  which  communicate  their  pulsations  to  them.  3.  They  re- 
ceive vessels  from  a  great  number  of  points,  and  the  vessels  themselves  are  very  numer- 
ous. 4.  They  are  penetrated  by  many  of  the  cerebro-spinal  nerves,  of  which  some  only 
pass  through,  but  a  certain  number  terminate  in  them.  5.  In  structure  they  resemble 
the  pancreas  and  the  lachrymal  glands ;  they  have  no  special  fibrous  investment  to  isolate 
them  completely  from  the  surrounding  parts  ;  they  have  no  precise  form,  and  they  are 
subdivided  into  lobes  and  lobules.  6.  Their  excretory  ducts  pour  their  secretion  into  the 
mouth,  i.  e.,  the  parotids  between  the  cheeks  and  the  teeth,  the  sub-maxillary  and  the 
sub-lingual  glands  behind  the  lower  incisors,  on  each  side  of  the  apex  of  the  tongue. 
This  distribution  of  the  means  of  insalivation  between  the  two  cavities  into  which  the 
mouth  is  divided  deserves  the  attention  of  physiologists. 

The  Buccal  Muccnis  Membrane. 

The  buccal  mucous  membrane  is  continuous  with  the  skin  at  the  free  edges  of  the  lips ; 
it  lines  their  posterior  surface,  and  is  reflected  from  them  upon  each  of  the  maxillary 
bones,  forming  a  cul-de-sac  or  trench,  and  in  the  median  line  a  small  fold,  called  the  frae- 
niun  of  the  Ups.  About  a -line  and  a  half  or  two  lines  from  the  free  border  of  the  lips, 
it  changes  its  character,  and  constitutes  the  gums,  which  are  reflected  upon  themselves, 
so  as  to  become  continuous  with  the  fibro-mucous  membrane,  called  the  alveolo-dental 
periosteum. 

In  the  lower  jaw  the  mucous  membrane  passes  from  the  alveolar  border  to  the  lower 
wall  of  the  mouth,  and  from  it  to  the  under  surface  of  the  tongue.  At  the  point  of  re- 
flection in  the  median  line,  it  forms  the  fraenum  hnguae.  From  the  under  surface  of  the 
tongue,  the  raucous  membrane  passes  over  its  edges  and  upper  surface,  where  it  pre- 
sents the  peculiarities  already  described ;  and  in  being  reflected  from  the  base  of  the 
tongue  to  the  epiglottis,  it  forms  three  folds,  the  glosso-epiglottid,  so  as  to  become  con- 
tinuous on  the  one  hand  with  the  mucous  membrane  of  the  larynx,  and  on  the  other  with 
that  of  the  pharynx. 

In  the  upper  jaw  it  is  extended  from  the  upper  alveolar  border  upon  the  roof  of  the  pal- 
ate, passing  over  the  anterior  and  posterior  palatine  canals,  which  it  closes,  but  does  not 
enter.  From  the  roof  of  the  palate  it  passes  upon  the  velum,  and  is  continuous  with  the 
nasal  mucous  membrane  at  its  free  edge.  On  the  sides  it  forms  two  large  folds  for  the 
pillars  of  the  fauces,  lines  the  amygdaloid  excavation,  covers  the  tonsil,  and  becomes 
continuous  with  the  mucous  membrane  of  the  base  of  the  tongue  and  of  the  pharynx. 


#44  SPLANCHNOLOGY. 

At  the  sides  of  the  buccal  cavity  the  mucous  membrane  is  reflected  from  both  the  alveo- 
lar borders  upon  the  inner  surface  of  the  cheeks,  and  thus  forms  two  trenches.  At  the 
anterior  edge  of  the  ramus  of  the  jaw,  behind  the  molar  teeth,  it  is  elevated  by  a  saliva- 
ry gland,  which  marks  the  limit  between  the  cheeks  and  the  pillars  of  the  fauces.  Inside 
this  prominence  it  forms  a  cul-de-sac. 

The  buccal  mucous  membrane  sends  off  prolongations  into  the  numerous  canals  which 
open  into  the  mouth.  Thus,  on  the  floor  of  the  mouth  there  are  two  for  the  Whartonian 
ducts,  and  several  for  the  small  ducts  of  the  sub-lingual  glands.  Two  others  are  seen  on 
the  inner  sides  of  the  cheeks  for  the  ducts  of  Steno  ;  and  it  is  also  clear  that  it  must  pen- 
etrate into  the  thousands  of  other  orifices  with  which  the  mouth  is  studded  (those  of  the 
buccal,  labial,  palatine,  and  other  glands).  But  in  all  these  prolongations  its  structure 
is  modified,  and  it  becomes  exceedingly  thin.  It  has  been  proved  that  it  lines  not  only 
the  larger  ducts,  but  even  their  minutest  subdivisions.  Thus,  there  is  a  kind  of  parotitis, 
which  consists  in  inflanunation  of  the  lining  membrane  of  the  excretory  ducts  of  that 
gland ;  and  then  all  the  canals  are  filled  with  muco-puriform  secretion,  which  escapes 
by  the  buccal  orifice  when  the  gland  is  compressed.  The  numerous  openings  on  the 
surface  of  the  tonsil  are  formed  by  the  prolongations  of  this  membrane  into  the  cavities 
situated  in  its  interior. 

Although  the  different  parts  of  the  buccal  mucous  membrane  are  continuous,  they  do 
not  all  possess  the  same  characters.  Compare,  for  instance,  in  regard  to  their  density, 
thickness,  and  closeness  of  adhesion  to  the  subjacent  tissues,  the  mucous  membrane  of 
the  gums  and  palate  with  that  of  the  lips  and  cheeks,  or  the  membrane  covering  the  low- 
er with  that  upon  the  upper  surface  of  the  tongue,  or  the  mucous  membrane  of  the  free 
edge  of  the  velum  palati  with  that  of  the  arches  and  the  amygdaloid  excavation. 

The  two  principal  characters  of  the  buccal  mucous  membrane  are  the  following :  1 . 
The  presence  of  an  epidermis  or  epithelium*  (as  it  is  called  in  mucous  membranes). 
This  can  be  distinctly  demonstrated  by  maceration,  or  by  the  action  of  boiling  water  or 
some  acid  ;  by  any  of  these  means  a  pellicle  is  raised,  having  all  the  characters  of  an  ep- 
idermis. It  is  very  thick  upon  the  gums,  the  roof  of  the  palate,  and  upon  the  tongue, 
where  it  forms  a  horny  sheath  to  each  papilla.  To  the  existence  of  this  membrane,  and 
of  the  fluid  with  which  it  is  constantly  kept  moist,  we  must  attribute  the  possibility  of 
applying,  or,  rather,  running,  a  red-hot  iron  over  the  surface  of  the  tongue  without  burn- 
ing the  part.  2.  The  multiplicity  of  small  subjacent  glands,  so  near  to  each  other  in  some 
parts  as  to  form  a  continuous  layer.  These  glands  should  be  carefully  distinguished 
from  the  muciparous  follicles  or  crypts,  with  which  many  modern  anatomists  have 
conunonly  confounded  them.  To  these  two  characteristics  a  third  may  be  added,  pe- 
culiar to  some  portions  of  the  buccal  mucous  membrane,  viz.,  that  it  is  supported  by  a 
very  dense  fibrous  tissue,  with  which  it  is  completely  united.  This  fibrous  layer  is  per- 
fectly distinct  from  the  periosteum,  and  from  its  presence  the  mucous  membrane  should 
be  arranged  among  the  fibro-mucous  membranes. 

The  Pharynx. 

The  pharynx  (^opvyf,  the  throat,t  1,  2,  ^,fig.  140),  long  confounded  with  the  cesopha- 
gus,  under  the  common  name  of  gula  or  oesophagus,  is  a  muscular  and  membranous  semi- 
canal, perfectly  symmetrical,  and  situated  in  the  median  line :  it  is  a  sort  of  vestibule, 
common  to  the  digestive  and  the  respiratory  passages,  intermediate  between  tlie  buccal 
and  nasal  cavities  on  the  one  hand,  and  between  the  cesophagus  and  larynx  on  the  other. 
It  is  situated  deeply  in  front  of  the  vertebtral  column,  extending  from  the  basilar  process 
of  the  occipital  bone  to  opposite  the  fourth  or  fifth  cervical  vertebra  and  the  cricoid 
cartilage.     It  therefore  corresponds  to  the  parotid,  and  partly  to  the  supra-hyoid  regions. 

Its  dimensions  deserve  particular  attention.  It  is  smaller  than  the  mouth,  but  larger 
than  the  oesophagus,  which,  compared  to  it,  resembles  the  tube  of  a  funnel.  Hence  it 
follows,  that  foreign  bodies,  which  have  been  able  to  pass  along  the  mouth  and  pharynx, 
may  be  arrested  in  the  oesophagus. 

In  length  it  is  from  4  to  4^  inches,  which  may  be  increased  to  5^,  or  even  6^,  by  dis- 
tension, and  reduced  to  2^  by  the  greatest  possible  contraction,  which  is  limited  only  by 
the  contact  of  the  base  of  the  tongue  with  the  velum  palati  rendered  horizontal.  The 
length  of  the  pharynx,  therefore,  may  be  made  to  vary  about  4  inches. 

The  pharynx  undergoes  these  extreme  variations  both  in  deglutition  and  in  modula- 
ting the  voice  ;  in  effecting  which  latter  purpose,  it  acts  in  the  same  way  as  the  tube  of 
a  clarinet  or  flute.  Thus  considered,  the  entire  length  of  the  pharynx  may  be  divided 
into  three  parts,  a  nasal  (1,/^.  140),  a  buccal  or  guttural  (2),  and  a  laryngeal  (3)  portion. 
It  may  be  easily  seen  that  the  variations  in  length  affect  almost  exclusively  the  buccal 
portion,  into  which  the  air  is  received  after  escaping  from  the  larynx.  Now  these  vari- 
ations in  the  length  of  the  pharynx  have  the  same  influence  over  the  compass  of  the  hu- 

*  [The  existence  of  an  epithelium  is  common  to  all  mucous  membranes  ;  that  of  the  buccal  cavity  is  of  the 
squamous  variety.] 

t  The  term  pharynx  had  no  well-defined  meaning  among  the  ancients :  they  sometimps  used  it  to  designate 
•he  phftrynz,  properly  so  called  ;  sometimes  the  larynx. 


THE    PHARYNX.  345 

man  voice  as  the  differences  in  the  lengths  of  the  tubes  of  wind-instruments  h.iif  ii.ori 
the  sounds  produced  by  them. 

The  breadth  of  the  upper  or  nasal  portion  of  the  pharynx  is  measured  by  the  interval 
between  the  posterior  margins  of  the  internal  pterygoid  plates  :  it  is  about  one  inch,  and 
is  invariable.  In  the  buccal  portion  the  same  diameter  is  measured  by  the  interval  be- 
tween the  posterior  extremities  of  the  alveolar  borders,  and  is  about  two  inches  :  it  may 
be  diminished  to  one  inch  by  the  contraction  of  the  constrictor  muscles.  The  breadth 
of  the  larj-ngeal  portion  is  measured,  first,  by  the  interval  between  the  summits  of  the 
great  cornua  of  the  os  hyoides,  where  it  is  about  one  inch  and  near  two  lines  ;  then  by 
the  interval  between  the  superior  cornua  of  the  thyroid  cartilage,  which  is  an  inch  and 
two  or  three  lines  ;  and,  lastly,  by  the  interval  between  the  inferior  cornua  of  the  same 
cartilage,  about  eleven  or  twelve  lines.  The  contraction  of  this  laryngeal  portion  may 
be  carried  to  complete  obliteration  of  the  cavity. 

Both  the  buccal  and  laryngeal  portions,  therefore,  are  capable  of  contraction,  and  this 
always  takes  place  in  deglutition,  in  order  to  force  down  and  compress  the  alimentary 
m£iss.  Contraction  of  the  buccal  portion  also  takes  place  in  the  modulation  of  sounds : 
it  exerts  the  same  influence  over  the  compass  of  the  human  voice  as  the  contraction  of 
the  tubes  of  the  flute  or  clarinet  does  over  the  notes  of  those  instruments. 

The  antero-'posterior  dimensions  of  the  pharynx  are  not  subject  to  the  same  variations  as 
the  transverse  and  vertical,  on  account  of  the  presence  of  the  vertebral  column.  Its  en- 
largement in  this  direction  is  produced  during  that  period  in  the  act  of  deglutition  when 
the  leuynx  and  os  hyoides  are  carried  forward  and  upward,  and  its  diminution  at  the  time 
when  the  same  parts  are  carried  upward  and  backward.  The  antero-posterior  diameter 
of  the  pharynx  depends  upon  the  length  of  the  basilar  process  of  the  occipital  bone. 

Figure. — The  pharynx  does  not  form  a  complete  cavity  with  distinct  and  separate 
walls,  but,  rather,  hsdf  or  two  thirds  of  a  canal,  which  is  completed  in  part  by  several  or- 
gans otherwise  not  belonging  to  it.  Moreover,  the  pharynx,  from  its  commencement 
down  to  the  larynx,  is  habitually  open,  and  in  a  state  of  tension ;  its  walls  are  never  in 
apposition :  an  important  circumstance  in  reference  to  the  continual  passage  of  air 
through  its  nasal  and  buccal  portions.  This  tension  depends  on  its  attachment  to  the 
basilar  process,  and  to  the  fixed  points  at  its  sides,  and  also  upon  the  tendinous  struc- 
ture of  its  upper  portion.     Opposite  the  larynx  the  tension  ceases  to  exist. 

The  pharynx,  as  well  as  all  other  hollow  organs,  presents  an  external  and  an  internal 
surface. 

The  External  Surface. — ^This  is  in  relation  behind,  by  a  plane  surface,  with  the  verte- 
bral column  (see  fig.  140),  from  which  it  is  separated  by  the  long  muscles  of  the  neck 
and  the  anterior  recti  of  the  head.  It  glides,  by  means  of  some  very  loose  cellular  tissue, 
upon  the  fascia  covering  the  muscles  of  that  region  ;  and  when,  from  the  effect  of  in- 
flammation, this  cellular  tissue  becomes  dense,  the  movements  of  deglutition  cannot  be 
performed,  and  dysphagia  is  the  result.  The  relation  of  the  pharynx  to  the  vertebral  col- 
lunn  accounts  for  congestive  abscesses  of  the  neck  sometimes  opening  into  the  pharynx. 

At  the  sides  the  pharynx  is  separated  from  the  internal  pterygoid  muscle  by  a  triangular 
space,  broad  below  and  narrow  above,  occupied  by  the  internal  carotid  artery,  the  inter- 
nal jugular  vein,  and  the  pneumogastric,  glosso-pharyngeal,  hypo-glossal,  and  spinal  ac- 
cessory nerves,  all  being  surrounded  by  very  loose  cellular  tissue.  The  sides  of  the 
pharynx  are  also  indirectly  in  relation  with  the  parotid  gland  and  the  styloid  muscles. 
Lower  down,  the  pharynx  corresponds  to  a  great  number  of  lymphatic  glands,  and  to  the 
external  carotid  artery  and  its  branches. 

The  Internal  Surface. — In  order  to  examine  this  surface,  it  is  necessary  to  open  the 
pharynx  from  behind  by  a  vertical  incision.  We  shall  then  perceive  that  this  structure 
only  exists  behind  and  at  the  sides,  but  that  in  front  it  presents  a  great  number  of  open- 
ings {see  figs.  140,  141),  the  arrangement  of  which  is  of  great  interest. 

Proceeding  from  above  downward,  we  find,  1.  The  two  posterior  openings  of  the  na- 
sal fossa  (I),  quadrilateral  in  form,  having  their  longest  diameter  vertical,  and  separated 
from  each  other  by  the  posterior  edge  of  the  septum.  On  looking  into  them,  we  see  the 
posterior  extremities  of  the  turbinated  bones  and  the  terminations  of  the  several  mea- 
tuses. 2.  The  upper  surface  of  the  velum  palati  (c  a),  forming  an  inclined  plane,  which 
directs  the  mucous  secretions  into  the  throat.  3.  The  isthmus  of  the  fauces  (2),  of  a  sem- 
icircular form,  divided  into  two  arches,  and  exhibiting  the  pillars,  the  amygdaloid  ex- 
cavation, and  the  prominence  of  the  tonsils.  4.  The  superior  opening  of  the  larynx  (3), 
the  plane  of  which  is  directed  obliquely  upward  and  forward  {see  fig.  140) ;  the  epiglottis 
{i,fig.  140),  which  is  ordinarily  erect,  closes  this  opening  by  becoming  depressed  like  a 
valve.  5.  The  posterior  surface  of  the  larynx,  with  its  two  lateral  and  triangular  grooves, 
broad  above  and  narrow  below,  which  have  been  regarded  as  specially  intended  for  the 
swallowing  of  liquids,  which  thus  pass  on  each  side  of  the  laryngeal  opening. 

It  is  extremely  curious  and  highly  important  to  study  all  the  objects  displayed  in  the 
complicated  mechanism  of  the  pharynx  :  by  so  doing,  we  learn  how  the  air  passes  from 
the  nasal  fossa  and  mouth  into  the  pharynx,  and  thence  into  the  larynx,  into  which  it  is 
drawn  by  the  active  expansion  of  the  thorax,  without  ever  entering  the  (esophagus ; 

Xx 


1 


a^  SPLANCHNOLOGY. 

how  the  mucous  secretions  of  the  nose,  or  blood,  can  pass  from  the  nose  down  into  the 
mouth  and  throat ;  how  instruments  may  be  introduced  from  the  nasal  fossae  and  buccal 
cavity  into  the  oesophagus  and  larynx,  or  drawn  from  the  nose  into  the  mouth ;  and, 
lastly,  how  solids  and  liquids  can  pass  into  the  oesophagus  without  entering  the  air-pas- 
sages, or  why  they  sometimes  take  this  irregular  course. 

The  posterior  wall  of  the  ■pharynx  is  broader  in  the  buccal  region  than  either  above  or 
below  :  it  may  be  partially  seen  through  the  isthmus  of  the  fauces  in  the  living  subject. 
There  is  no  folding  of  the  membrane  upon  any  part  of  this  wall :  we  only  find  a  few 
glands  forming  projections  beneath  the  lining  membrane. 

On  each  lateral  wall  is  seen  the  expanded  orifice  of  the  corresponding  Eustachian  tube 
{A,  fig.  140),  and  a  groove  leading  from  it  downward  and  inward.  This  orifice  corre- 
sponds precisely  to  the  posterior  extremity  of  the  lower  turbinated  bone :  an  important 
relation,  because  it  serves  as  a  guide  in  the  now  common  operation  of  introducing  a 
catheter  into  the  Eustachian  tube. 

The  roof  of  the  pharynx  corresponds  to  the  basilar  process :  it  may  be  reached  by  the 
finger  introduced  into  the  mouth,  if  it  be  curved  directly  upward. 

There  is  no  very  distinct  line  of  demarcation,  either  internally  or  externally,  between 
the  pharynx  and  the  oesophagus  (y,  fig.  140).  Their  limits  are  established  by  a  sudden 
narrowing  of  the  tube,*  by  a  change  of  colour  in  the  lining  membrane,  and  by  a  change 
in  the  direction  and  colour  of  the  muscular  fibres,  which  are  red  in  the  pharynx  and 
much  paler  in  the  oesophagus. 

Structure  of  the  Pharynx. — The  pharynx  is  composed  of  an  aponeurotic  portion,  of 
muscles,  of  vessels  and  nerves,  and  of  a  lining  mucous  membrane. 

The  aponeurotic  portion,  or  framework  of  the  pharynx,  is  composed  of  the  cephalo-pha- 
ryngeal  aponeurosis  and  of  the  petro-pharyngeal  aponeurosis. 

The  cephalo-pharyngeal,  or  posterior  aponeurosis  of  the  pharynx,  arises  from  the  lower 
surface  of  the  basilar  process,  from  the  Eustachian  tubes,  and  from  the  contiguous  parts 
of  the  petrous  portions  of  each  temporal  bone  :  it  is  continuous  above  with  the  thick  pe- 
riosteum which  covers  the  basilar  process,  is  prolonged  vertically  downward,  and,  grad- 
ually diminishing  in  thickness,  is  lost  after  extending  about  an  inch  and  a  half  or  two 
inches.     On  this  membrane  the  constrictor  muscles  of  the  pharynx  terminate. 

The  petro-pharyngeal,  or  lateral  aponeurosis  of  the  pharynx,  arises  from  the  petrous 
portion  of  the' temporal  bone,  internally  to  the  inferior  orifice  of  the  carotid  canal,  by  a 
very  thick  tendinous  bundle,  continuous,  at  a  right  angle,  with  the  cephedo-pharyngeal 
aponeurosis  ;i  it  then  descends  along  the  sides  of  the  pharynx,  and  splits  into  bundles, 
which  are  inserted  into  the  pterygoid  fossa  between  the  internal  pterygoid  muscle  and 
the  circumflexus  palati,  separating  these  muscles  from  each  other.  From  thence  it 
gives  off  to  the  posterior  extremity  of  the  inferior  alveolar  border  a  fibrous  prolongation, 
to  the  front  of  which  the  buccinator  muscle  is  attached.  This  aponeurosis  covers  the 
tonsil,  to  which  it  is  closely  united.  It  is  prolonged  downward  as  far  as  the  upper  bor- 
der of  the  OS  hyoides,  in  order  to  form  the  framework  of  the  side  and  lower  part  of  the 
pharynx. 

Muscles  of  the  Pharynx. 
The  muscles  of  the  pharynx  are  divided  into  intrinsic  and  extrinsic. 

The  Intrinsic  Muscles. 
The  intrinsic  muscles  have  a  membranous  form,  and  are  arranged  in  three  successive 
imbricated  layers.  Santorini  described  a  great  many  muscles  in  the  pharj'nx,  on  ac- 
count of  their  numerous  attachments  ;  but  Albinus  has  reduced  them  to  three  on  each 
side,  named  constrictors,  distinguished  into  an  inferior,  a  middle,  and  a  superior.  Chaus- 
sier  united  all  the  muscles  which  enter  into  the  composition  of  the  pharynx  under  the 
collective  name  of  les  stylo-pharyngiena.  The  division  of  Albinus  has  been  generally  and 
justly  preferred. 

^'  !*'•  The  Inferior  Constrictor. 

This  is  a  membranous  muscle  (w,figs.  141,  147),  of  a  lozenge, 
or,  rather,  a  trapezoid  shape,  the  most  superficial  and  the  thick- 
est of  all  the  muscles  of  the  pharynx,  and  is  situated  at  the  low- 
er part  of  that  cavity.  It  is  attached,  on  the  one  hand,  to  the  cri- 
coid and  the  thyroid  cartilages,  and,  on  the  other,  to  the  fibro- 
cellular  raphe,  along  the  posterior  median  line  of  the  pharynx 
(crico-pharyngien  and  thyro-pharyngien,  Valsalva,  Winslow,  and 
Santorini).  It  might  be  called  the  crico-thyro-pharyngeus.  It 
-m  arises  upon  the  side  of  the  cricoid  cartilage,  from  a  triangu- 
lar space  bounded  in  front  by  the  crico-thyroideus  (a,  fig.  147), 

*  [This  occurs  exactly  opposite  the  cricoid  cartilage.] 

+  The  superior  cervical  ganglion  of  the  sympathetic  nerve  lies  upon  the  angle 
formed  by  these  two  aponeuroses, 


MUSCLES   OP   THE    PHARYNX.  347 

from  which  it  often  receives  some  fibres,  and  behind  by  the  crico-arytenoideus  posticus 
(i,fig.  141). 

Its  thyroid  origins  are  much  more  extensive,  and  take  place  from  an  imaginary  ob- 
lique line  on  the  outer  surface  of  that  cartilage,  from  the  two  tubercles  at  the  extremi- 
ties of  that  line,  and  from  the  entire  surface  behind  it ;  also  from  the  upper  and  poste- 
rior borders,  and  from  the  corresponding  inferior  comu  of  the  same  cartilage.  Having 
thus  arisen  by  two  very  distinct  digitations,  the  fleshy  fibres  pass  in  different  direc- 
tions :  the  inferior  fibres,  short  and  horizontal,  proceed  directly  inward  ;  the  superior  be- 
come longer,  and  are  directed  more  obliquely  upward,  in  proportion  as  they  approach 
the  upper  part  of  the  muscle  :  they  terminate  by  an  expanded  border  of  much  greater 
extent  than  the  outer  border,  and  the  upper  extremity  of  which  rarely  extends  above 
the  middle  of  the  pharynx.  The  transverse  direction  and  the  shortness  of  the  inferior 
fibres  have  obtained  for  them  the  name  of  the  (Esophageal  muscle  ( Wiiislow,  Santorini). 

Relations. — Covered  by  a  dense  cellular  membrane,  which  surrounds  the  entire  pha- 
rynx, and  which  might  be  regarded  as  the  proper  sheath  of  its  muscles,  the  inferior  con- 
strictor has  the  same  relations  posteriorly  as  the  pharynx  itself  Externally  it  is  cov- 
ered by  the  sterno-thyroid  muscle  and  the  thyroid  body.  It  covers  the  middle  constric- 
tor, the  stylo-pharjmgeus,  and  palato-pharyngeus,  and,  for  a  great  part  of  its  extent,  it  is 
in  contact  with  the  mucous  membrane  of  the  pharynx  (see  figs.  141,  147).  The  recur- 
rent larjTigeal  nerve  passes  undSr  the  lower  margin  of  this  muscle,  near  its  cricoid  at- 
tachment, in  order  to  enter  the  larynx.  Its  ufper  margin  is  well  defined  from  the  other 
constrictors  by  a  tolerably  distinct  ridge,  and  by  the  passage  of  the  superior  laryngeal 
nerve  beneath  it.  Winslow  states  that  he  has  seen  some  fibres  of  the  muscle  arise  from 
the  thyroid  body ;  and  Morgagni,  that  he  has  traced  some  from  the  first  ring  of  the 
trachea. 

Action. — It  is  simply  a  constrictor  in  its  lower  portion :  its  upper  fibres  act  as  a  con- 
strictor, a  depressor,  and  a  tensor  of  the  posterior  wall  of  the  pharynx ;  it  can  also  raise 
the  larynx,  and  carry  it  backward. 

The  Middle  Constrictor. 

This  is  a  membranous  triangular  muscle  {v,  figs.  141,  147),  situated  in  the  middle  of 
the  pharynx,  upon  a  plane  anterior  to  the  preceding. 

It  arises  from  the  os  hyoides,  and  is  inserted  into  the  posterior  median  raphe  {hyo-pha- 
ryngeus).  It  arises  from  the  os  hyoides  in  the  following  manner :  1.  From  the  whole  ex- 
tent of  the  upper  surface  of  the  great  comu  below  the  hyo-glossus  {t),  from  which  it  is 
separated  by  the  lingual  artery  ;  a  great  many  fibres  arise  by  a  tendinous  origin  from  the 
apex  of  this  comu.  2.  From  the  lesser  comu  and  the  contiguous  part  of  the  stylo-hyoid 
ligament.  From  these  difTerent  origins,  which  form  the  external  truncated  angle  of  the 
muscle,  the  fleshy  fibres  diverge  in  various  directions  ;  the  inferior  passing  downward, 
the  middle  transversely,  and  the  superior  upward  :  the  latter  are  much  more  oblique  and 
more  numerous  than  the  others,  and  terminate  in  a  pointed  extremity,  which  never  reach- 
es as  high  as  the  basilar  process. 

Relations. — Its  external  surface  is  in  a  great  measure  superficial,  and  is  in  relation  with 
the  muscles  of  the  prae-vertebral  region,  through  the  medium  of  the  cellular  investment 
of  the  pharynx.  It  is  covered,  in  the  rest  of  its  extent,  by  the  inferior  constrictor  and 
the  hyo-glossus.  It  covers  the  mucous  membrane  of  the  pharynx,  the  superior  constric- 
tor, the  stylo-pharyngeus,  and  the  palato-pharyngeus.  Its  upper  margin  may  be  dis- 
tinguished from  the  superior  constrictor  by  its  projecting  slightly  behind  that  muscle,  and 
by  the  stylo-pharyngeus  (r),  which  lifts  up  this  border  in  penetrating  into  the  pharynx. 

Action. — It  is  a  constrictor  of  the  pharynx,  and  can  draw  the  os  hyoides  upward  and 
backward. 

The  Superior  Constrictor. 

This  is  a  quadrilateral  muscle  {g,figs.  141,  147),  occupying  the  upper  part  of  the  pha- 
rynx ;  it  arises  from  the  pterygoid  process,  the  mylo-hyoid  ridge,  and  the  base  of  the 
tongue,  and  is  inserted  into  the  posterior  median  raphe  {pterygo-pharyngeus,  buccinato- 
pharyngeus,  mylo-pharyngeus,  and  glosso-pharyngeus,  Santorini). 

It  arises,  1.  By  tendinous  fibres,  from  the  lower  third  of  the  margin  of  the  internal 
pterygoid  plate  and  its  hamular  process.  2.  From  the  contiguous  portion  of  the  palate 
bone,  and  the  reflected  tendon  of  the  circumflexus  palati.  3.  From  the  buccinato-pha- 
ryngeal  aponeurosis,  which  extends  from  the  pterygoid  process  to  the  posterior  extrem- 
ity of  the  inferior  alveolar  arch.*  4.  From  the  posterior  extremity  of  the  mylo-hyoid 
line.  5.  The  fibres  which  are  said  to  arise  from  the  base  of  the  tongue  are  nothing 
more  than  those  fibres  of  the  genio-hyo-glossus,  which  Winslow  has  described  as  le  ge- 
nio-pharyngien.  These  are  the  same  fibres,  so  difficult  to  demonstrate,  which  Valsalva 
and  Santorini  have  regarded  as  forming  a  particular  muscle,  denominated  by  them  the 
glosso-pharyngeus. 

From  these  different  origins  the  fleshy  fibres  curve  backward,  and  then  pass  trans- 

*  As  this  same  aponeurosis  gives  attachment  to  the  buccinator,  it  may  be  conceived  that  the  contruction  ot 
that  muscle  cannot  be  altogether  without  effect  upon  the  pharynx. 


^Ml  SPLANCHXOLOGT. 

versely  inward ;  the  superior  form  a  sort  of  arch,  having  its  concavity  directed  upward 
{see  Jigs.  141,  147),  and  are  inserted  into  the  cephalo-pharyngeal  aponeurosis  :  they  form 
the  ccphalo-pharyngeus  muscle  of  some  authors,  which  is  said  to  be  continued  from  one 
side  to  the  other  without  any  intermediate  raphe.  This  muscle  forms  a  very  thin  layer, 
the  fibres  of  which  are  paler  and  less  distinct  than  those  of  the  other  constrictors. 

Relations. — Its  external  surface  is  partly  covered  by  the  preceding  muscle,  and  has  be- 
hind, and  on  the  sides,  the  same  relations  as  the  pharynx.  This  muscle  forms  the  inner 
side  of  a  triangular  space  already  described  (p.  345)  (the  maxillo-pharyngeal),  the  outer 
side  of  which  is  formed  by  the  ramus  of  the  lower  jaw  and  the  internal  pterygoid  mus- 
cle {b,fig.  141),  and  which  is  occupied  by  the  internal  carotid  artery,  the  internal  jugu- 
lar vein,  and  the  pneumogastric,  h)T)0-glossal,  and  spinal  accessory  nerves. 

Its  internal  surface  (fig.  141)  is  in  relation  with  the  pharyngeal  mucous  membrane, 
with  the  levator  palati  (c),  which  it  separates  from  the  circumflexus  palati  (d),  and  with 
the  palato-pharyngeus  (c). 

Action. — It  is  a  constrictor. 

Remarks. — From  the  preceding  description,  it  follows,  1.  That  the  constrictors  of  the 
pharynx  form  three  super-imposed  or,  rather,  imbricated  muscular  layers.  This  imbrica- 
tion, or  overlapping,  is  so  arranged  that  the  projections  (very  slight,  it  is  true)  formed 
by  the  upper  margins  of  the  constrictors  are  on  the  outer,  not  on  the  inner  surface  of 
the  pharynx  ;  and  this  has,  perhaps,  some  relation  to^he  downward  course  of  the  ali- 
mentary mass.*  2.  That  the  thickest  part  of  the  muscular  layer  formed  by  the  constric- 
tors is  opposite  the  buccal  portion  of  the  pharynx,  where  the  lower  and  middle  constric- 
tors overlap  ;  and  that  the  thinnest  part  is  in  the  nasal  portion,  which  is  formed  by  the 
superior  constrictor  alone.  3.  That  the  pharyngeal  insertions  of  all  the  constrictors  are 
upon  a  single  line,  the  median  raphe,  while  their  points  of  origin  are  exceedingly  nu- 
merous, viz.,  commencing  from  below,  the  cricoid  cartilage,  the  thyroid  cartilage,  the  great 
and  lesser  cornua  of  the  os  hyoides,  the  base  of  the  tongue,  the  mylo-hyoid  line,  the  buc- 
cinato-pharyngeal  aponeurosis,  and,  lastly,  the  pterygoid  process. 

The  Extrinsic  Muscles. 

The  extrinsic  muscles  of  the  pharynx  are  generally  two  in  number,  the  stylo-pharyn- 
geus  and  the  palato-pharyngeus.  The  latter  has  been  already  described  among  the  mus- 
cles of  the  velum  palati.  It  is  by  no  means  uncommon  to  find  several  supernumerary 
muscles 

The  Stylo-pharyngeus. 

This  muscle  (r,  figs.  143,  147),  which  is  round  above  and  broad  and  thin  below,  arises 
by  tendinous  and  fleshy  fibres  from  the  inner  side  of  the  base  of  the  styloid  process,  or, 
rather,  from  the  vaginal  process  surrounding  that  base.  From  this  point  it  passes  down- 
ward and  inward,  becomes  wider  and  flattened  as  it  enters  the  pharynx  between  the 
middle  and  superior  constrictors,  to  spread  out  beneath  the  mucous  membrane.  Its  up- 
per fibres  ascend,  the  middle  are  transverse,  and  the  lower  fibres  descend  to  terminate 
along  the  posterior  border  of  the  thyroid  cartilage!  (see  jig.  143).  These  fibres,  togeth- 
er with  those  of  the  palato-pharyngeus,  form  the  fourth  muscular  layer  of  the  pharynx. 

Relations. — Before  entering  the  pharynx,  the  stylo-pharyngeus  is  in  relation  on  the  out- 
side with  the  stylo-glossus  muscle  (u),  the  external  carotid  artery,  and  the  parotid  gland ; 
on  the  inside,  with  the  internal  carotid  and  the  internal  jugular  vein.  Its  most  interest- 
ing relation  is  with  the  glosso-pharyngeal  nerve,  which  runs  along  its  outer  side.  Some 
branches  of  the  nerve  often  pass  through  it.  In  the  pharynx  it  is  covered  by  the  middle 
constrictor,  and  it  lies  outside  the  superior  constrictor,  the  palato-pharyngeus,  and  the 
mucous  membrane. 

Actimi. — It  raises  the  larynx  and  the  pharynx. 

Supernumerary  Muscles  of  the  Pharynx. 
Among  the  supernumerary  extrinsic  muscles  of  the  pharynx,  I  shall  notice,  1.  A  fascicu- 
lus pointed  out  by  Albinus,  which  I  have  often  met  with  :  it  arises  from  the  petrous  portion 
of  the  temporal  bone,  and  passes  into  the  walls  of  the  pharynx ;  it  is  the  petro-pharyn- 
geus  of  some  authors.  2.  A  very  strong  fasciculus,  arising  from  the  basilar  process  in 
front  of  the  foramen  magnum,  passing  downward  and  inward,  and  interlacing  with  its 
fellow  of  the  opposite  side  in  the  median  line  :  it  may  be  called  the  occipito-pharyngeus. 
3.  A  small  muscle,  which  I  have  seen  arising  by  well-marked  tendinous  fibres  from  the 
summit  of  the  hamular  process  of  the  internal  pterygoid  plate,  passing  obhquely  inward 
and  downward,  and  expanding  on  the  walls  of  the  pharynx ;  it  may  be  called  the  extrin- 
sic pterygo-pharyngeus.  4.  Riolanus  has  described  a  spheno-pharyngeus  arising  from  the 
spinous  process  of  the  sphenoid,  and  Santorini  and  Winslow  have  noticed  a  salpingo-pha- 
ryngeus  arising  from  the  cartilaginous  portion  of  the  Eustachian  tube  and  the  contiguous 
bone,  and  blended  in  the  pharynx  with  the  palato-pharyngeus.  » 

*  In  the  construction  of  pipes  or  tunnels  for  the  conveyance  of  water,  &c.,  each  piece  is  received  into  that 
below  it ;  an  opposite  arrangement  would  facilitate  the  blocking  up  of  the  pipe. 

+  Some  anatomists  affirm  that  they  have  seen  fibres  from  this  muscle  reaching  the  base  of  the  tongue,  the 
epiglottis,  and  the  os  hyoides. 


SUPERNUMERARY    MUSCLES    OF   THE    PHARYNX.  349 

Such,  then,  are  the  muscles  of  the  pharynx.  They  are  all,  as  we  have  seen,  constric- 
tors, and  at  the  same  time  elevators,  in  consequence  of  their  fibres  rising  to  a  greater 
height  internally  upon  the  median  line  than  they  do  externally ;  the  stylo-pharyngeus 
alone  can  be  regarded  as  a  dilator.  Indeed,  dilatation  is  chiefly  effected  by  the  muscles 
of  the  OS  hyoides,  by  the  action  of  which  the  larynx  is  carried  upward  and  forward ;  we 
may,  therefore,  with  Haller,  consider  them  as  extrinsic  muscles  of  the  pharynx. 

Pharyngeal  Mucous  Membrane. — The  muscular  semi-canal  of  the  pharynx  is  lined  by  a 
mucous  membrane  continuous  with  the  buccal  and  nasal  mucous  membranes  on  the  one 
hand,  and  with  those  of  the  larynx  and  oesophagus  on  the  other.  This  membrane,  which 
is  of  a  reddish  colour,  presents  some  peculiarities  at  different  parts  of  its  extent.  Above, 
near  the  basilar  process,  it  is  thick,  and,  as  it  were,  fungous,  and  closely  united  to  the 
periosteum,  from  which,  indeed,  it  cannot  be  separated ;  in  this  region  it  is  very  liable 
to  become  the  seat  of  fibrous  polypi.  Near  the  posterior  orifices  of  the  nasal  fossae  and 
the  openings  of  the  Eustachian  tubes,  it  is,  in  some  respects,  similar  to  the  pituitary 
membrane.*  It  forms  a  sort  of  rim  around  the  trumpet-shaped  orifice  of  the  Eustachian 
tube,  into  which  it  is  prolonged  in  a  remarkable  manner,  gradually  becoming  thinner, 
and  at  length  continuous  with  the  lining  membrane  of  the  cavity  of  the  tympanum.  This 
continuity  of  the  mucous  membrane  of  the  pharynx  and  Eustachian  tube  explains  the 
close  sympathy  between  these  parts,  and  also  the  deafness  which  so  frequently  follows 
chronic  sore  throats  and  coryzae,  in  consequence  of  the  obstruction  of  these  tubes. 

In  its  buccal  portion  it  exactly  resembles  the  mucous  membrane,  upon  the  lower  sur- 
face of  the  velum  palati :  the  part  covering  the  posterior  surface  of  the  larynx  is  pale, 
and  forms  several  folds. 

The  mucous  membrane  of  the  pharynx  adheres  to  the  subjacent  muscles  only  through 
the  medium  of  very  loose  cellular  tissue,  which  is  never  loaded  with  fat,  nor  infiltrated 
with  serosity.     It  is  ■still  less  intimately  adherent  to  the  posterior  surface  of  the  larynx. 

Its  surface  is  raised  by  a  great  number  of  small  glands,  chiefly  occupying  the  upper 
part  of  the  pharynx,  near  the  posterior  nares  :  we  shall  divide  them  into  agglomerated 
and  solitary.  Two  agglomerated  glands  are  always  situated  around  the  orifices  of  the 
Eustachian  tube  ;  they  open  upon  the  mucous  membrane,  either  separately  or  together. 
These  glands  are  sometimes  arranged  in  a  line,  sometimes  in  several  parallel  rows. 
Haller  believes  that  the  salpingo-pharyngeus  of  Santorini  and  Winslow  is  nothing  more 
than  a  series  of  these  glands  united  together  by  fibrous  tissue.  The  solitary  glands  are 
scattered  over  the  whole  extent  of  the  pharynx.  Lastly,  the  pharyngeal  mucous  mem- 
brane is  provided  with  a  thin  epithelium,!  which  can  be  easily  demonstrated  by  macer- 
ation and  the  action  of  acids. 

Vessels  and  Nerves. — The  pharynx  receives  a  principal  artery  on  each  side,  viz.,  the 
inferior  pharyngeal,  a  branch  of  the  internal  carotid.  The  superior  pharyngeal  branch 
of  the  internal  maxillary,  and  some  small  twigs  from  the  palatine  and  the  superior  thy- 
roid, complete  its  arterial  system. 

Its  veins  form  a  very  considerable  plexus  around  it  (the  pharyngeal  venous  plexus),  and 
terminate  in  the  internal  jugular  and  superior  thyroid.  The  lymphatiXhessels  are  little 
known ;  they  pass  into  the  glands  lying  along  the  internal  jugular  vein.  Its  nerves  are 
very  numerous,  and  form  a  remarkable  plexus — the  pharyngeal,  which  I  regard  as  one 
of  the  largest  in  the  body.  They  are  derived  from  two  sources  :  1 .  From  the  cerebro- 
spinal axis,  viz.,  the  pharyngeal  nerve,  a  branch  of  the  pneumogastric,  which  appears  to 
be  principally  distributed  to  the  muscular  layer  ;  the  glosso-pharyngeal,  which  appears  to 
be  chiefly  destined  for  the  mucous  membrane ;  and,  lastly,  some  branches  of  the  supe- 
rior laryngeal  and  the  spinal  accessory.  2.  From  the  ganglionic  system,  several  large, 
gray,  and  soft  branches  being  distributed  to  it  from  the  superior  cervical  ganglion. 

This  abundance  of  nerves,  and  also  the  sources  from  which  they  are  derived,  will 
serve  to  explain,  1.  The  great  sensibility  of  the  pharynx,  to  which  part  we  refer  the 
feeling  of  thirst,  which  some  have,  therefore,  proposed  to  term  the  pharyngeal  sense ; 
2.  The  part  which  it  performs  in  the  perception  of  certain  flavours,  for  example,  those 
of  acids  ;  3.  The  sympathy  between  the  pharynx,  the  base  of  the  tongue,  and  the  stom- 
ach ;  4.  The  feeUngs  of  constriction  and  strangulation,  so  common  in  the  pharynx ;  5 
The  spasms  with  which  it  is  affected  in  tetanus  and  hydrophobia ;  and,  6.  The  nature 
of  the  globus  hystericus,  &c.t 

Development. — The  development  of  the  pharynx  offers  no  remarkable  phenomena  •, 
still,  it  is  an  exception  to  the  general  law  of  bilateral  development,  laid  down  by  some 
anatomists. 

Uses  of  the  Pharynx. — ^The  pharynx  is  one  of  the  principal  organs  of  deglutition.    It 

*  See  note,  infra.  . 

t  [According  to  Dr.  Henl6,  the  upper  part  of  the  mucous  membrane  of  the  pharynx  is  covered  with  a  <^U** 
*ed  columnar  epithelium,  as  far  down  as  a  horizontal  line  extending  from  the  lowei  border  of  the  atlas  to  the 
floor  of  the  nasal  fossa  ;  below  that  line  the  epithelium  assumes  the  squamous  form,  and  is  not  cihated.  In 
the  Eustachian  tube  it  is  also  columnar,  and  provided  with  cilia ;  but  in  the  cavity  of  the  tympanum  it  is 
squamous,  and  destitute  of  those  organs.]  , 

i  We  cannot  explain  why  the  syphilitic  virus  has  so  serious  a  predilection  for  the  mucous  membrane  ot  the 
pharynx. 


SPLANCHNOLOGY. 

serves  also  for  the  passage  of  air  in  respiration,  and  as  a  tube  for  modulating  the  voice. 
The  importance  of  the  pharynx  in  this  last  point  of  view,  and  the  influence  which  its  dif- 
ferent degrees  of  shortening  and  constriction  exercise  upon  the  compass  of  the  voice, 
do  not  appear  to  me  to  have  sufficiently  engaged  the  attention  of  physiologists. 

The  CEsophagus. 

Tlie  (esophagus  {olau,  I  will  convey,  and  ^ayw,  I  eat)  is  a  musculo-membranous  canal, 
an  organ  of  deglutition,  intended  to  convey  the  food  from  the  pharynx  into  the  stomach. 
It  occupies  the  lower  part  of  the  cervical  region  and  all  the  thoracic  region,  and  perfo- 
rates the  diaphragm,  in  order  to  terminate  in  the  stomach. 

Directions. — It  is  situated  in  the  median  line,  resting  against  the  vertebral  column  ; 
its  general  direction  is  straight,  for  the  food  does  not  remain  in  it ;  nevertheless,  it  pre- 
sents several  slight  curves  ;  at  its  commencement  it  is  exactly  in  the  middle  line,  but 
inclines  somewhat  to  the  left  side  in  the  neck ;  in  the  upper  part  of  the  thorax  it  deviates 
slightly  to  the  right  side,  then  again  becomes  median,  and,  lastly,  inclines  to  the  left, 
where  it  passes  through  the  diaphragm.  The  general  direction  of  the  oesophagus  per- 
mits the  introduction  of  straight  probangs  into  the  stomach.  The  inflection  which  it 
undergoes  at  its  entrance  into  the  thorax  explains  the  reason  why  these  instruments 
are  sometimes  arrested  opposite  the  first  rib. 

Dimensions. — The  length  of  the  oesophagus  corresponds  to  the  interval  between  the 
pharynx  and  the  stomach,  i.  e.,  the  space  between  the  fifth  cervical  vertebra,  or  the  cri- 
coid cartilage,  and  the  tenth  dorsal  vertebra.  In  regard  to  its  calibre,  or  diameter,  the 
oesophagus  is  the  narrowest  part  of  the  alimentary  canal.  Its  diameter  is  not  uniform 
throughout,  the  cervical  portion*  being  certainly  the  narrowest ;  and,  therefore,  foreign 
bodies  which  are  too  large  to  pass  through  the  alimentary  canal,  are  generally  arrested 
in  the  neck.    The  widest  portion  of  the  oesophagus  is  its  lower  end. 

The  oesophagus  is  capable  of  a  certain  degree  of  dilatation,  as  is  proved  by  the  passage 
of  large  foreign  bodies  for  a  considerable  distance  through  it  (Mim.  d'Hivin,  Acad.  Roy. 
de  Chirurgie),  sometimes  even  aa  far  as  the  stomach.  That  this  dilatability,  however, 
is  very  limited,  may  be  inferred  from  the  pain  caused  by  swallowing  too  large  a  morsel, 
and  also  from  the  stoppage  of  foreign  bodies  in  the  gullet.  Nevertheless,  in  some  CEises, 
from  external  pressure  upon,  or  from  stricture  of,  some  part  of  this  canal,  it  becomes 
greatly  enlarged  above  the  seat  of  obstruction,  and  forms  a  sort  of  ampulla  or  dilatation 
resembling  the  crop  in  gedlinaceous  birds.  In  one  case  I  found  a  sort  of  pouch,  or  di- 
verticulum, of  the  mucous  membrane,  of  considerable  size,  protruding  between  the  sep- 
arated muscular  fibres,  and  at  first  sight  resembling  the  crop  of  gallinaceous  birds.  An 
example  has  been  recorded  of  dangerous  suffocation  occasioned  by  the  pressure  of  ali- 
mentary matters  in  a  cavity  of  that  kind. 

Figure. — The  oesophagus  is  cylindrical,  and  differs  from  the  rest  of  the  alimentary 
canal  in  never  containing  any  air,  so  that  (when  at  rest)  its  parietes  are  always  in  con- 
tact. It  is  somewhat  flattened,  and,  as  it  were,  compressed,  at  its  upper  part ;  but  be- 
low it  always  pre|pnts  the  appearance  of  a  solid  cylinder,  or  a  dense  firm  cord.  This 
appearance  exists  through  its  whole  extent  in  some  animals,  the  horse,  for  example. 

Like  all  hollow  organs,  the  oesophagus  presents  two  surfaces,  an  external  and  an  in- 
ternal. 

The  external  surface.  In  its  long  course  the  oesophagus  has  many  relations,  all  ol 
which  are  of  great  importance,  and  must  be  examined  in  the  neck,  in  the  thorax,  and  in 
the  abdomen. 

In  its  cervical  portion  (y.  Jigs.  1 14,  140),  the  oesophagus  is  in  relation  in  front  with  the 
membranous  portion  of  the  trachea  {x),  beyond  which  it  projects  a  little  on  the  left  side. 
The  cellular  tissue  uniting  these  two  canals  is  most  condensed  above.  All  that  portion 
which  projects  beyond  the  trachea  comes  into  relation  with  the  left  sterno-thyroid  muscle 
(71,  fig.  1 14),  the  thyroid  body  {z),  the  left  recurrent  laryngeal  nerve,  and  the  inferior  thy- 
roid vessels,  which  cross  it  at  right  angles.  The  relation  of  the  oesophagus  to  the  tra- 
chea explains  how  foreign  bodies  arrested  in  the  former  passage  may  compress  the  tra- 
chea, and  impede  or  even  prevent  respiration.  The  deviation  of  the  oesophagus  to  the 
left  is  the  reason  for  selecting  that  side  for  the  performance  of  oesophagotomy.  Behind, 
it  corresponds  to  the  longi  colli  muscles  and  to  the  vertebral  column,  being  united  to 
them  by  loose  cellular  tissue,  so  that  it  is  enabled  to  execute  those  movements  which 
are  necessary  for  the  performance  of  its  functions.  Laterally,  it  corresponds  to  the  thy- 
roid body,  the  common  carotid  artery,  and  the  internal  jugular  vein  ;  but  these  relations 
are  somewhat  modified  on  each  side,  in  consequence  of  the  deviation  of  the  oesophagus. 
Thus,  the  relations  of  the  oesophagus  with  the  left  common  carotid  are  much  more  im- 
mediate than  those  with  the  right.  The  left  recurrent  nerve  lies  in  front  of  the  oesopha- 
gus, the  right  nerve  a  Uttle  behind  it. 

Its  thoracic  portion  (o,  fig.  161)  is  situated  in  the  posterior  mediastinum,  and  is  in  rela- 
tion in  front,  commencing  from  above,  with  the  trachea,  then  with  its  bifurcation,  and 
slightly  also  with  the  left  bronchus,  which  crosses  it  obliquely,  and  which  may  be  com- 

*  [Opposite  the  cricoid  cartilage.l 


THE    OESOPHAGUS.  351 

pressed  by  it  during  the  retention  of  a  foreign  body  (an  example  of  this  accident  has  been 
recorded  by  Habicot) ;  lastly,  it  is  situated  opposite  and  behind  the  ascending  portion  of 
the  arch  of  the  aorta,  and  the  base  and  posterior  surface  of  the  heart,  from  which  parts 
it  is  separated  by  the  pericardium.  Behind,  it  is  in  relation  with  the  longus  colli  and  the 
vertebral  column,  to  which,  however,  it  is  not  so  closely  applied  as  in  the  neck  ;  nor  does 
it  follow  the  curvature  of  the  spine  in  the  dorsal  region,  but  is  separated  from  it  by  a 
space  filled  with  cellular  tissue,  lymphatic  glands,  the  vena  azygos,  and  the  thoracic  duct, 
the  latter  being  placed  to  its  right  side,  at  the  lower  part  of  the  thorax,  but  passing  be- 
hind it  above,  so  as  to  reach  the  left  side.  Below,  at  the  point  where  the  oesophagus 
deviates  to  the  left  side,  in  order  to  gain  the  opening  of  the  diaphragm,  it  lies  in  front  of 
the  aorta.  On  each  side  it  forms  a  projection  along  the  wall  of  the  mediastinum,  which 
is  thus  brought  into  relation  with  the  corresponding  lung ;  it  is  much  more  prominent  on 
the  right  than  on  the  left  side.  On  the  left  side  it  is  also  in  contact,  in  its  entire  extent, 
with  the  thoracic  aorta  (h,fig.  161),  which  is  situated  a  little  behind  it.  Above,  it  has 
immediate  relations  with  the  arch  of  the  aorta,  as  that  vessel  is  passing  backward  and 
to  the  left  side  of  the  vertebral  column.  It  is  commonly,  at  this  point,  that  aneurisms 
of  the  aorta  open  into  the  oesophagus. 

In  all  this  region  the  oesophagus  is  enveloped  by  a  serous  cellular  tissue,  extremely 
loose  and  very  abundant ;  it  is  surrounded  by  a  great  number  ofljrmphatic  glands,  which 
have  been  improperly  named  oesophageal.  These  glands,  when  enlarged,  sometimes 
compress  the  gullet  so  much  as  completely  to  arrest  deglutition.  Lastly,  the  two  pneu- 
mogastric  nerves  run  along  each  side  of  the  oesophagus  ;  inferiorly  the  left  comes  in  front, 
and  the  right  retires  behind  the  canal :  they  communicate  with  each  other  throughout 
their  course  by  loops  or  arches,  which,  perhaps,  explains  the  pain  caused  by  swallowing 
too  large  a  mass  of  food. 

In  its  abdominal  portion  (if  such  can  be  said  to  exist),  the  oesophagus  is  in  relation  with 
the  oesophageal  opening  of  the  diaphragm,  below  which  it  is  entirely  covered  by  the 
peritoneum.  On  the  right  side  and  in  front  it  is  embraced  by  the  left  extremity  of  the 
liver  ;  behind,  by  the  lobulus  Spigelii.  In  some  subjects  the  abdominal  portion  of  the 
oesophagus  is  an  inch  in  length,  but  this,  I  think,  is  occasioned  by  descent  of  the  stomach. 

The  internal  surface  is  remarkable  for  its  pale  colour,  which  contrasts  strongly  with  the 
rosy  hue  of  the  stomach  and  the  upper  part  of  the  pharynx,  for  the  vsTinkling  of  its  pa- 
rietes  and  their  contact  with  each  other,  and,  lastly,  for  its  longitudinal  folds,  which 
seem  to  have  reference  to  the  necessity  for  its  momentary  distension  during  the  mere 
passage  of  the  food  through  it. 

Structure. — The  oesophagus  is  essentially  composed  of  two  cyhndrical  membranes,  one 
internal  or  mucous,  the  other  external  or  muscular. 

The  muscular  coat  is  remarkable  for  its  thickness,  which  greatly  exceeds  that  of  any 
other  part  of  the  alimentary  canal,  and  is  connected  with  the  necessity  for  the  rapid  pas- 
sage of  the  alimentary  mass  from  the  pharynx  into  the  stomach.  It  is  susceptible  of  hy- 
pertrophy, as  we  find  in  cases  of  stricture  of  the  lower  part  of  the  gullet.  I  have  seen 
it  five  or  six  lines  thick.  In  all  herbivorous  animals  in  which  the  oesophagus  is  almost 
incessantly  in  action,  in  those  in  which  the  food  is  carried  upward  in  opposition  to  grav- 
ity during  the  act  of  deglutition,  in  the  horse  and  in  ruminants,  the  muscular  coat  is  still 
more  developed  than  in  man. 

The  muscular  coat  is  of  a  red  colour  immediately  below  the  pharynx,  and  rosy  through 
the  rest  of  its  extent,  but  of  a  darker  tint  than  in  the  succeeding  portion  of  the  aliment- 
ary canal.     It  is  of  a  vivid  red  in  herbivora.* 

This  coat  is  composed  of  two  very  distinct  layers,  the  external  consisting  of  longitu- 
dinal fibres  regularly  disposed  upon  all  sides  of  the  oesophagus  ;  the  internal,  of  circular 
fibres,  in  which  we  shall  in  vain  seek  for  the  spiral  arrangement  described  by  some  anat- 
omists as  existing  in  animals  and  in  man.t  The  longitudinal  fibres  seem  to  arise,  at 
least  in  part,  from  the  posterior  surface  of  the  cricoid  cartilage,  in  the  median  line,  be- 
tween the  two  posterior  crico-arytenoid  muscles  ;  they  evidently  become  continuous  be- 
low with  the  longitudinal  muscular  fibres  of  the  stomach.  The  first  muscular  ring  of  the 
oesophagus  appears  to  arise  from  the  cricoid  cartilage  ;  it  has  been  designated  the  crico- 
msophageus.  There  is  no  sphincter,  as  some  anatomists  have  affirmed,  round  the  lower 
extremity  of  the  oesophagus. 

The  Mucous  Membrane. — As  Bichat  has  remarked,  the  mucous  membrane  of  the  oesoph- 
agus is,  perhaps,  next  to  the  buccal,  the  thickest  in  the  alimentary  canal.  By  a  remark- 
able exception  (also  observed  in  the  rectum),  its  outer  surface  is  united  to  the  adjacent 
membrane  by  a  very  loose  cellular  tissue  ;  so  that  the  whole  mucous  cylinder  may  be 
removed  entire  from  the  sort  of  muscular  sheath  in  which  it  is  contained.  It  has  even 
been  said  that  the  muscular  coat  can  force  the  mucous  membrane  downward  by  its  con- 
traction, so  as  to  produce  a  projecting  rim  around  the  cardiac  orifice  of  the  stomach, 
jmalogous  to  that  which  is  formed  at  the  anus  in  prolapsus.     The  longitudinal  folds  of 

*  [It  consists  of  involuntary  muscular  fibres  (note,  p.  323),  intermixed  with  fibres  possessing  transverse  stnte.] 
i  [These  fibres  are  obviously  spiral  in  the  ruminant,  and  many  other  mammalia  ] 


352 


SPLANCHNOLOGY. 


the  mucous  membrane  are  not  caused  by  the  contraction  and  elasticity  of  the  circular 
fibres  of  the  muscular  coat,  but  depend  upon  a  peculiarity  of  structure.  If  the  first  hy- 
pothesis be  correct,  why  should  not  the  mucous  membrane  also  present  transverse  folds 
from  the  action  of  the  longitudinal  fibres  \  for  the  extremities  of  the  oesophagus  are  not  so 
fixed,  nor  is  its  tension  so  great  that  it  could  not  be  shortened  by  the  action  of  these  fibres. 

Besides  the  longitudinal  folds,  there  are  also  in  the  oesophagus  a  number  of  wrinkles 
analogous  to  those  of  the  skin,  and,  therefore,  irregular ;  they  appear  to  me  to  be  caused 
by  the  elasticity  of  the  muscular  fibres. 

The  mucous  membrane  of  the  oesophagus  has  a  thick  epithelium,  which  may  be  easily 
shown  by  maceration  and  the  action  of  acids,  or  even  without  preparation,  and  which 
terminates  at  the  cardiac  orifice  of  the  stomach  by  an  irregularly  fringed  or  festooned 
border.* 

When  examined  by  the  microscope,  the  free  surface  of  the  mucous  membrane  pre- 
sents a  number  of  small  linear  ridges,  running  vertically,  and  united  together  by  other 
oblique  ridges,  so  that  the  whole  surface  has  a  reticulated  aspect.  These  ridges  are 
formed  by  papillae  or  villosities,  the  arteries  and  veins  of  which  have  been  accurately 
figured  by  Bleuland. 

The  surface  of  the  mucous  membrane  is  raised  in  various  places  by  small,  oblong,  and 
flat  glands  found  here  and  there  over  the  entire  oesophagus.  They  were  first  described 
by  Steno,  and  should  be  carefully  distinguished  from  the  oesophageal  lymphatic  glands : 
the  latter  are  external  to  the  oesophagus,  and,  in  certain  animals,  frequently  contain  small 
entozoa :  they  have  been  supposed  to  open  into  the  oesophagus,  and  to  deposite  within  it 
a  fluid  containing  these  animalcules,  which  some  physiologists  have  regarded  as  the 
chief  agent  in  digestion.  Any  communication,  however,  between  these  lymphatic  glands 
and  the  cavity  of  the  gullet  is  purely  accidental.  The  true  oesophageal  glands  are  very 
numerous.! 

In  the  oesophagus,  there  is  only  a  trace  of  the  fibrous  membrane,  which  forms  the  frame- 
work of  the  alimentary  canal ;  it  adheres  to  the  muscular  coat,  and  is,  therefore,  but 
loosely  attached  to  the  mucous  membrane. 

There  is  no  external  serous  membrane  ;  it  would  not  have  yielded  to  the  instantane- 
ous dilatation  required  in  the  cesophagus.  The  two  laminse  of  the  posterior  mediasti. 
num  corresponding  to  its  sides  may  be  regarded  as  forming  the  rudiment  of  a  serous  coat. 

Vessels  and  Nerves. — The  (esophageal  arteries  are  numerous,  and  arise  from  several 
sources.  They  may  be  distinguished  into  the  cervical,  proceeding  from  the  inferior  thy- 
roid ;  the  thoracic,  given  off  either  directly  from  the  aorta  or  from  the  bronchial  and  in- 
tercostal arteries,  and  sometimes  from  the  internal  manmiary ;  and,  lastly,  the  abdominal, 
arising  from  the  coronary  artery  of  the  stomach,  and  the  inferior  phrenic. 

The  vei7is  terminate  in  the  inferior  thyroid,  the  superior  cava,  the  azygos,  the  internal 
manunary,  the  bronchial,  the  phrenic,  and  the  coronary  of  the  stomach. 

The  lymphatic  vessels  enter  the  numerous  glands  which  surround  the  oesophagus. 

The  7ierves  are  very  numerous,  and  are  derived  from  the  pneumogastrics,  which  sur- 
round the  oesophagus  with  a  series  of  loops  ;  these  are  joined  by  some  branches  from  the 
thoracic  ganglia  oi  the  sympathetic. 

The  development  of  the  cesophagus  presents  nothing  worthy  of  notice. 

Functions. — The  cesophagus  is  intended  to  convey  the  food  rapidly  from  the  pharynx 
to  the  stomach.  This  function  is  performed  by  its  longitudinal  fibres  shortening  the  pas- 
sage, and  by  its  circular  fibres  contracting  it  successively  from  above  downward  during 
deglutition ;  in  vomiting  or  regurgitation,  the  contraction  proceeds  from  below  upward. 


Fig.  148. 


The  Stomach. 

The  stomach  {yaarfip,  ventriculus),  one  of  the  princi- 
pal organs  of  digestion,  is  that  wide  dilatation  {s,  fig. 
139)  of  the  ahmentary  canal,  intervening  between  the 
cesophagus  (a)  and  the  duodenum  (i  c),  in  which  the 
food  is  collected  and  converted  into  chyme. 

Situation. — It  is  situated  at  the  junction  of  the  upper 
tenth  with  the  lower  nine  tenths  of  the  alimentary  ca- 
nal, between  the  organs  of  deglutition  and  those  of 
chylification.  It  occupies  the  upper  part  of  the  abdom- 
inal cavity  («,  figs.  155,  161),  almost  entirely  fills  the 
left  hypochondrium,  and  advances  into  the  epigastri- 
um, as  far  as  the  limits  of  the  right  hypochondrium.i: 

*  [The  epithelium  is,  in  fact,  continued  on  through  the  rest  of 
the  alimentary  canal,  but  becomes  thinner,  and  assumes  a  different 
character  :  in  the  cesophagus  it  is  squamous.] 

t  [Especially  around  the  lower  extremity  of  the  gullet.] 
t  [In  order  to  facilitate  the  description  of  the  viscera  contained 
in  the  abdominal  cavity,  anatomists  have  adopted  the  following  ar- 
tificial division  of  that  cavity  into  several  regions  :     The  abdomen 
is  first  divided  into  three  zones  by  two  horizontal  lines,  one  (o  a 


THE   STOMACH.  353 

It  is  maintained  in  its  place  by  the  oesophagus  and  duodenum,  and  also  by  some  folds 
of  the  peritoneum,  which  connect  it  with  the  diaphragm,  the  hver,  and  the  spleen.  The 
stomach  is,  therefore,  less  subject  to  displacement  than  most  of  the  abdominal  viscera. 
It  may  even  be  generally  stated,  that  almost  all  the  changes  in  the  relative  situation  ol 
this  organ  are  the  results  of  displacements  or  alterations  in  the  size  of  those  organs 
which  are  connected  with  it.  I  do  not  here  refer  to  examples  of  complete  transposition 
of  the  viscera,  nor  to  those  cases  of  malformation  of  the  diaphragm,  in  which  the  stom- 
ach has  been  found  in  the  thorax. 

Direction. — The  stomach  is  directed  obliquely  downward  to  the  right  side,  and  a  little 
forward  ;  this  direction  affords  some  explanation  of  the  almost  constant  habit  of  lying 
on  the  right  side  during  sleep,  and  why  the  rest  is  disturbed  and  digestion  rendered  diffi- 
cult in  those  who  lie  upon  the  left  side.  Changes  in  direction  of  the  stomach  depend 
upon  the  same  causes  as  changes  in  its  situation.  Thus,  dragging  produced  by  displace- 
ment of  the  small  intestine  or  the  omentum,  enlargements  of  the  liver  or  spleen,  or  the 
use  of  too  tight  stays,*  must  necessarily  affect  the  direction  of  this  organ.  We  not  un- 
frequently  find  stomachs  having  a  vertical  direction. 

Number. — The  stomach  is  single  in  the  human  subject  as  well  as  in  the  greater  num- 
ber of  animals.  The  examples  of  double  or  triple  stomachs  in  the  human  subject  are 
merely  cases  of  single  stomachs  having  one  or  more  circular  constrictions. t  The  es- 
sential character  of  a  double  stomach  is  not  an  accidental  or  even  a  congenital  contrac- 
tion, but  a  difference  in  structure.  Bilocular  stomachs,  indeed,  are  very  common ;  but 
this  form  (resembling  that  of  some  kinds  of  calabash-gourds),  though  sometimes  extreme- 
ly well  marked  when  the  stomach  is  empty,  disappears  ahnost  entirely  when  it  is  much 
distended  by  inflation. 

Size. — In  all  animals,  the  stomach  is  the  most  capacious  part  of  the  alimentary  canal ; 
so  that,  in  many  species,  where  its  limits  are  not  so  clearly  defined  as  in  man,  the  ex- 
istence of  a  stomach  is  determined  only  by  the  presence  of  a  dilatation.  It  is  of  consid- 
erable size  in  herbivora,  but  comparatively  much  smaller  in  camivora.  The  human 
stomach  is  intermediate  between  these  extremes — a  fact  which  affords  evidence  of  its 
adaptation  to  both  vegetable  and  aliment  diet.  The  human  stomach,  however,  presents 
innumerable  varieties  in  size,  from  a  state  of  extreme  contraction,  in  which  it  scarcely 
exceeds  the  duodenum,  to  such  an  enormous  degree  of  dilatation  that  it  occupies  a  third, 
a  half,  or  even  almost  the  whole,  of  the  abdominal  cavity.  These  differences  depend 
less  upon  original  variations,  than  upon  its  peculiarly  dilatable  and  elastic  structure, 
which  enables  it  to  contain  a  large  quantity  of  food,  and  to  contract  more  or  less  com- 
pletely upon  itself  when  empty.  Thus,  the  stomach  has  a  much  greater  capacity  in  those 
who  adopt  the  bad  habit  of  eating  only  one  very  full  meal  in  the  twenty-four  hours,  than 
in  those  who  eat  more  frequently,  but  less  abundantly.  In  some  cases  of  stricture  at  the 
pylorus,  it  becomes  enormously  distended.  Long-continued  abstinence  occasions  such 
an  amount  of  contraction,  that  it  has  even  been  asserted,  that  pain  resulting  from  the 
rubbing  of  its  parietes  together  gives  rise  to  the  feeling  of  hunger ;  but  this  completely 
mechanical  hypothesis  should  be  rejected.  In  a  great  number  of  cholera  patients,  the 
stomach  was  found  to  be  exceedingly  small.  In  a  female,  who  died  a  month  after  hav- 
ing voluntarily  swallowed  a  small  quantity  of  sulphuric  acid,  the  contracted  stomach  was 
not  larger  than  a  moderately-sized  gall-bladder. 

Figure. — The  stomach  resembles  a  flattened  cone,  curved  upon  itself  backward  and 
upward,  and  having  a  rounded  base  ;  it  has  been  compared  to  the  bladder  of  a  bagpipe. 
Sections  made  at  right  angles  to  its  axis  represent  circles  gradually  decreasing  in  size 
from  the  entrance  of  the  oesophagus  to  the  pylorus.  We  have  to  examine  its  external 
and  its  internal  surface. 

The  external  surface.  From  the  peculiar  form  of  the  stomach,  we  are  enabled  to  con- 
sider an  anterior  and  a  posterior  surface,  a  convex  border  or  great  curvature,  and  a  con- 
cave border  or  lesser  curvature,  a  great  cul-de-sac  or  tuberosity,  an  oesophagal  extremi- 
ty, cuid  a  pyloric  extremity. 

The  anterior  surface  (upper  surface  of  some  anatomists,  s,Jig.  155)  is  directed  forward, 
and  a  little  upward.  When  inflated  in  the  dead  body  with  the  abdomen  open,  it  is  turn- 
ed directly  upward ;  but  such  cannot  take  place,  either  in  the  living  or  dead  subject, 

fig.  148)  extending  between  the  most  prominent  points  of  the  cartilages  of  the  ribs,  and  the  other  {f>  b)  be- 
tween the  crests  of  the  iliac  bones.  The  superior  zone  is  called  the  epigastric  ;  the  middle,  the  umbilical ; 
and  the  inferior,  the  hypogastric.  These  three  zones  are  then  subdivided  by  two  vertical  parallel  lines  drawn 
from  the  cartilages  of  the  eighth  rib  down  to  the  centre  of  Poupart's  ligament.  The  epigastric  zone  is  thus 
divided  into  two  hypochondriac  (1  Ij^and  a  middle  epigastric  region  (2)  ;  the  umbilical  into  two  lumbar  (3  3), 
and  a  middle  umbilical  region  (4)  ;  and  the  hypogastric  into  two  iliac  (5  5),  and  a  middle  hypogastric  region  (6).] 

*  It  is  impossible  to  insist  too  strongly  upon  the  influence  of  too  tight  stays  on  the  situation,  and  even  the 
form,  of  the  viscera  occupying  the  base  of  the  thorax.  Thus,  changes  in  the  situation  and  direction  of  the 
stomach  are  much  more  frequent  in  females  than  in  males.  Soemmering  observed,  but  without  stating  the 
cause,  that  the  stomach  is  more  rounded  in  the  male,  and  more  oblong  in  the  female. 

t  It  may,  strictly  speaking,  be  stated  that  ruminants  have  only  one  stomach,  the  rennet  or  obomasum;  and 
that  the  iirst  three,  viz.,  the  paunch,  the  reticulum,  and  the  manypHes  or  omasum,  are  nothing  more  than  dila- 
tations of  the  oesophagus,  in  which  the  food  undergoes  a  preparatory  elaboration.  The  same  observation  ap- 
plies to  birds,  in  which  the  crop  and  the  gizzard  are  not  organs  of  chymification,  the  first  being  merely  an  or- 
?ar  of  insalivation,  the  second  one  of  trituration. 

Yy 


364  SPLANCHNOLOGY. 

when  the  abdominal  parietes  are  entire ;  in  which  case  the  distended  stomach  passes  in 
the  direction  of  the  least  resistance,  i.  e.,  forward  and  downward,  and  its  anterior  sur- 
face cannot  then  be  completely  turned  up. 

This  surface  is  in  relation  with  the  diaphragm,  and  is  separated  by  it  from  the  heart ; 
with  the  liver,  which  is  prolonged  upon  it  to  a  greater  or  less  extent  ;*  with  the  last  six 
ribs,  being  separated  from  them  by  the  diaphragm  ;  and  with  the  abdominal  parietes  in 
the  epigastrium  :  hence  the  name  given  to  that  region.  It  is  not  uncommon  to  find  the 
great  omentum  turned  upward  between  the  stomach  and  the  liver.  When  distended, 
the  stomach  has  much  more  extensive  relations  with  the  epigastrium,  or,  rather,  with 
the  abdominal  parietes,  both  in  a  vertical  and  transverse  direction. 

All  these  relations  are  of  the  greatest  importance ;  and,  with  the  exception  of  those 
which  concern  the  epigastrium,  they  are  constant.  In  fact,  it  rarely  happens  that  the 
stomach  precisely  corresponds  to  the  sub-sternal  or  xiphoid  depression,  which  has  been 
called  the  pit  of  the  stomach,  or  the  scrobiculus  cordis,  but  which  belongs  neither  to  the 
heart  nor  the  stomach.  In  exploring  this  depression,  it  is  almost  always  the  liver  wliich 
is  felt ;  the  stomach  lies  lower  down,  and  is  generally  below  the  ensiform  appendix. 

The  posterior  surface  {inferior  surface  of  some  anatomists,  seen  turned  up  at  s,fig.  154) 
is  directed  downward  and  backwjurd,  and  is  seen  in  the  sac  of  the  omentum,  of  which 
it  forms  the  anterior  wall. 

It  has  relations  with  the  transverse  mesocolon,  which  serves  as  a  floor  for  it,  and  sep- 
arates it  from  the  convolutions  of  the  small  intestines  ;  with  the  third  portion  of  the  duo- 
denum (e'  to  b),  by  some  of  the  older  anatomists  called  the  pillow  of  the  stomach  {ven- 
triculi  pulvinar) ;  and,  lastly,  with  the  pancreas  (o).  The  duodenum,  the  pancreas,  the 
aorta  (a),  and  the  pillars  of  the  diaphragm  {d  d),  separate  it  from  the  vertebral  column, 
upon  which  it  rests  obUquely.  These  relations  are  modified  by  the  emptiness  or  fulness 
of  the  stomach. 

The  great  curvature  (the  inferior  or  anterior  border  of  some  anatomists,  cad,  fig.  149) 
Fig.  149.  is  convex,  and  directed  almost  vertically  downward 

in  the  empty  condition  of  the  organ,  and  almost  di- 
rectly forward  when  it  is  full ;  it  gives  attachment 
to  the  two  anterior  layers  of  the  great  omentum.  It 
is  in  relation  with  the  abdominal  parietes  and  the 
cartilages  of  the  lower  ribs,  and  lies  along  the  trans- 
1^  verse  arch  of  the  colon  (,t,Jlg.  155),  in  front  of  which 
it  advances  when  considerably  distended  ;  hence  it 
was  termed  the  colic  border  by  Chaussier.  In  the 
distended  state  its  relations  with  the  abdominal  pa- 
rietes become  much  more  extensive  ;  but  even  then  I 
can  scarcely  believe  the  assertions  of  some,  that  the 
pulsations  of  the  gastro-epiploic  arteries  can  be  felt  by  the  finger  in  emaciated  individuals. 
The  lesser  curvature  (the  superior  or  posterior  border  of  some  anatomists,  o  b  p,  fig.  149) 
is  concave,  and  extends  from  the  oesophageal  orifice  to  the  pylorus  ;  it  gives  attachment 
to  the  small  or  gastro-hepatic  omentum  ;  it  is  directed  upward  when  the  viscus  is  empty, 
upward  and  backward  when  it  is  full ;  and  it  then  embraces  the  vertebral  column  in  its 
curvature,  being  separated  from  it  by  the  aorta  and  the  pillars  of  the  diaphragm  (see^^. 
154) ;  it  also  embraces  the  small  lobe  of  the  liver  or  the  lobulus  Spigehi,  the  coeliac  axis 
(f),  and  the  solar  plexus  of  nerves. 

The  great  extremity  or  great  cul-de-sac  of  the  stomach  (the  bottom  or  great  tuberosity,  from 
c  to  the  dotted  line,  fig.  149)  comprises  all  that  portion  which  is  to  the  left  of  the  car- 
diac or  cEsophageal  opening  ;  it  is  a  sort  of  semi-spheroid,  applied  to  the  base  of  the  cone 
formed  by  the  rest  of  the  stomach  ;  it  is  the  highest  and  the  largest  portion  of  that  or- 
gan ;  it  is  almost  entirely  absent  in  carnivora  ;  it  is  very  large  in  herbivora,  and  of  a 
medium  size  in  man.  There  are  also  many  individual  varieties  in  the  size  of  this  por- 
tion of  the  stomach  ;  I  have  met  with  some  instances  in  which  it  W2is  not  larger  than  it 
is  in  carnivora. 

It  is  in  contact  with  the  spleen  {k,  fig.  154)  (hence  it  is  called  the  splenic  extremity  by 
Chaussier),  with  which  it  is  connected  by  a  fold  of  the  peritoneum,  called  the  gastro- 
splenic  omentum,  and  by  the  vasa  brevia.  When  the  stomach  is  distended  it  comes  into 
close  contact  with,  and  is,  as  it  were,  moulded  upon,  the  spleen  (see  fig.  161).  From  this 
relation  a  great  number  of  physiological  inferences  may  be  deduced. t  The  great  cul- 
de-sac  occupies  the  left  hypochondrium,  and  corresponds  also,  in  the  greater  part  of  its 

*  The  relations  of  the  anterior  surface  of  the  stomach  with  the  liver  are  very  variable  in  extent ;  it  some- 
times reaches  even  to  the  gall-bladder.  I  have  seen  a  case  in  vphich  the  gall-bladder  adhered  to  the  anterior 
surface  of  the  stomach,  and,  therefore,  to  the  left  of  the  pylorus,  and  communicated  with  it  by  an  orifice,  through 
■which  bile  and  biliary  calculi  were  discharged. 

t  The  great  end  of  the  stomach  is  so  closely  connected  with  the  spleen,  that  it  necessarily  follows  all  dis- 
placements of  that  organ.  I  have  met  with  a  case  in  which  the  spleen,  three  or  four  times  its  natural  size, 
■was  situated  in  the  umbilical  region,  and  had  dragged  down  the  great  end  of  the  stomach  with  it.  The  left 
extremity  of  the  transverse  colon,  and  the  upper  part  of  the  descending  colon,  occupied  the  place  of  the  great 
extremity  of  the  stomach.  The  patient  had  long  suffered  from  indigestion,  which  had  been  attributed  to  chron- 
ic gastritis. 


THE   STOMACH.  355 

extent,  to  the  left  half  of  the  diaphragm,  which  is  in  accurate  contact  with  it,  and  separ- 
ates it  from  the  lungs  above  and  from  the  last  six  ribs  in  front.  It  is  more  or  less  ele- 
vated, according  to  the  degree  of  distension  of  the  stomach  ;  and  from  this  we  can  easi- 
ly understand  that  difficult  respiration  may  be  caused  by  too  large  a  meal. 

Lastly,  it  may  be  stated  that  the  great  extremity  of  the  stomach  has  relations  behind 
with  the  pancreas,  and  with  the  left  kidney  and  supra-renal  capsule. 

The  (Esophageal  extremity  (o,  Jig.  149).  The  oesophagus  opens  into  the  stomach  at 
different  angles,  according  to  the  emptiness  or  fulness  of  that  organ.  The  situation  of 
this  opening,  which  is  improperly  denominated  the  cardia  {cor,  heart),  is  at  the  left  ex- 
tremity of  the  lesser  curvature,  to  the  right  of  the  great  cul-de-sac,  and  opposite  the 
(Esophageal  opening  in  the  diaphragm.  It  is  embraced  (c.  Jig.  154)  in  front  by  the  left 
extremity  of  the  liver,  which  sometimes  forms  a  half  circle  round  it,  and  behind  by  the 
lobulus  Spigelii.  It  is  surrounded  by  a  circle  of  vessels  and  some  nerves.  Examined 
externally,  the  lower  end  of  the  oesophagus  is  continuous  with  the  stomach,  without  any 
other  line  of  demarcation  than  that  depending  upon  a  difference  in  size  and  direction. 
The  peritoneum  is  directly  reflected  from  the  diaphragm  upon  the  oesophagus  and  the 
stomach,  and  forms  the  gastro-diaphragmatic  fold  (ligamentum  phrenico-gastricum. 
ScBJnmerifig).* 

The  pyloric  extremity  {pylorus,  from  ttCIt],  a  gate,  and  o^pof,  a  keeper,  p,figs.  149,  &c.) 
iS  situated  at  the  right  extremity  of  the  stomach.  It  forms  the  apex  of  the  cone,  and 
presents  a  circular  constriction  or  strangulation,  which  exactly  defines  the  limits  between 
the  stomach  and  duodenum.  About  an  inch  from  this  constriction  the  stomach  is  much 
curved,  so  as  to  form  a  decided  bend,  and  presents  a  dilatation,  on  the  side  of  the  great 
curvature  corresponding  to  an  internal  excavation,  called  by  Willis  the  antrum  pylori,  and 
by  others  the  srnall  cul-de-sac  of  the  stomach  (from  d  to  the  dotted  line  e).  Not  uncom- 
monly we  find  a  second  dilatation  near  the  first,  and  a  third,  still  smaller,  on  the  side  of 
the  lesser  curvature,  resulting  from  the  bend  formed  by  the  stomach.  The  pyloric  ex- 
tremity of  the  stomach  is  directed  to  the  right  side,  backward  and  upward,  and  some- 
times even  a  little  to  the  left,  when  the  stomach  is  much  distended. 

The  relations  of  the  pyloric  extremity  with  the  abdominal  parietes  are  very  variable,  for 
the  changes  in  the  situation  of  the  stomach  chiefly  affect  this  extremity.  It  corresponds 
to  the  liaiit  between  the  epigastrium  and  the  right  hypochondrium  ;  sometimes  it  is  in 
relation  with  the  gall-bladder,  and  hence  may  become  stained ;  in  some  cases  it  passes 
to  the  right  of  the  gall-bladder,  to  the  extent  of  an  inch  or  an  inch  and  a  half.  I  have 
seen  it  occupying  the  horizontal  fissure  of  the  hver,  the  edges  of  which  were  separated 
for  its  reception.  Very  commonly  we  find  the  pylorus  in  the  umbilical  region.  I  have 
seen  it  in  the  hypogastrium  in  a  female  who  was  affected  vdth  schirrus  of  the  pylorus, 
and  I  have  also  found  it  in  the  right  iliac  fossa.  It  is,  therefore,  extremely  difficult  to 
determine  the  seat  of  an  organic  lesion  of  the  pylorus  from  external  examination. 

The  relations  of  the  pylorus  with  the  abdominal  viscera  are  more  constant :  above,  it 
corresponds  to  the  liver  and  the  lesser  omentum  ;  below,  to  the  great  omentum  ;  in  front, 
to  the  abdominal  parietes  ;  and  behind,  to  the  pancreas.  It  is  not  uncommon  to  find  it 
adhering  to  the  gall-bladder.  # 

The  Internal  Surface. — This  presents  the  same  regions  as  the  external  surface  ;  all  its 
peculiarities  may  be  referred  to  the  raucous  membrane,  which  will  be  noticed  when  the 
structure  of  the  stomach  is  described.  Besides  these,  however,  we  observe  here  the 
two  orifices  of  the  stomach. 

The  oesophageal  orifice  (cardiac,  left,  or  superior  orifice,  ostium  iiitroitus,  o,  Jig.  150)  is 
remarkable  for  its  radiated  folds  (ad  steUae  similitudi-  pj    UO 

nem.  Holler),  which  are  effaced  by  distension ;  for  the       ^, 

irregularly  fringed  border  and  the  change  in  colour      ^  ,•  ,  ?  \ 

which  mark  the  limits  between  the  mucous  membrane 
of  the  oesophagus  and  of  the  stomach  ;  for  its  size  and 
its  capabihty  of  dilatation ;  and,  lastly,  for  the  total  ab- 
sence of  any  valve  or  sphincter. 

The  duodenal  or  pyloric  orifice  (right  or  anterior  ori- 
fice, janitor,  sphinctor,  ostium,  exitus,  p)  is  remarkable 
for  an  internal  rim,  or  circular  valve,  which  in  a  distend- 
ed and  dried  stomach  forms  a  sort  of  diaphragm  (in 
speciem  diaphragmatis,  quedia  sunt  in  tubis  telescopicis,  Morgagni) ;  for  the  narrowness 
of  the  passage,  which,  with  difficulty,  admits  the  little  finger  in  most  subjects  ;  for  its  slight 
dilatability ;  and,  lastly,  for  the  existence  of  a  muscular  ring,  which  may  be  regarded  as 
a  true  sphincter.  It  is  of  importance  to  remark,  that  this  orifice,  independently  of  ajiy 
disease,  presents  a  great  number  of  varieties  in  its  dimensions,  and  it  is  probable  that 
these  congenital  or  acquired  variations  may  have  some  influence  upon  its  diseases. 

The  relative  position  of  these  two  orifices  is  an  important  anatomical  point.  Upon 
this  we  should  observe,  1.  That  they  are  but  little  apart  from  each  other,  considering 

*  [Hence  this  extremity  is  comparatively  fixed.] 


356 


SPLANCHNOLOGY. 


the  size  of  the  stomach,  and  that  the  interval  between  them  does  not  increase  in  propor- 
tion to  that  size  ;  2.  That  the  oesophageal  orifice  is  directed  upward,  the  pyloric  open- 
ing backward  and  a  little  upward ;  3.  That  the  two  openings  are  not  upon  the  same  plane, 
the  oesophageal  being  higher  and  more  posterior  than  the  pyloric. 

The  Structure  of  the  Stomach. — In  order  to  study  the  structure  of  the  stomach,  it  is 
necessary,  in  the  first  place,  to  distend  it.  Two  stomachs  are  indispensable  for  this  pur- 
pose, one  to  be  dissected  from  without  inward,  and  the  other  from  within  outward. 
One  of  the  stomachs  should  be  everted,  and  then  inflated. 

The  parietes  of  the  stomach  are  formed  by  the  super-position  of  four  membranes  or 
coats,  differing  in  texture  and  properties.  These,  proceeding  from  without  inward,  are 
the  serous,  the  muscular,  the  fibrous,  and  the  mucous  coats.  We  must  also  examine  the 
vessels,  nerves,  and  cellular  tissue,  which  enter  into  the  composition  of  these  parietes. 

1.  The  serous  or  ■peritoneal  coat.  Like  almost  all  the  movable  viscera  of  the  abdomen, 
the  stomach  receives  a  complete  covering  from  the  'peritoneum  {membrana  communis  of 
the  ancients  ;  la  membrane  capsulaire,  Chauss.).  It  is  formed  in  the  following  manner  : 
Two  layers  of  the''peritoneum,  in  contact  with  each  other,  pass  from  the  transverse  fis- 
sure of  the  liver  to  the  lesser  curvature  of  the  stomach :  there  they  separate,  so  as  to 
leave  between  them  a  triangular  space,  the  base  of  which  corresponds  to  the  lesser  curva- 
ture ;  the  anterior  layer  then  passes  over  the  anterior  surface  of  the  stomach,  and  the  pos- 
terior covers  it  behind ;  they  again  approach  each  other  at  the  great  curvature,  along  which 
they  form  another  triangular  space,  exactly  resembling  that  which  we  have  already  de- 
scribed as  existing  at  the  lesser  curvature,  and  then  unite  so  as  to  form  the  two  ante- 
rior layers  of  the  great  omentum  (see  description  of  Peritoneum).  The  same  airange- 
ment  takes  place  at  the  great  extremity  of  the  stomach.  Bloodvessels  pass  round  the 
stomach,  along  the  line  where  the  two  layers  of  the  peritoneum  are  applied  to  each  oth- 
er at  its  two  curvatures. 

The  peritoneum,  therefore,  forms  a  complete  covering  for  the  stomach,  excepting  at 
the  curvatures,  where  we  find  triangular  spaces,  into  which  the  stomach  is  forced  during 
its  distension.  I  doubt  whether  these  triangular  spaces  can  afibrd  sufficient  space  for 
the  stomach  when  greatly  distended,  and  I  believe  that,  in  such  cases,  the  two  anterior 
layers  of  the  great  omentum  separate,  and  are  applied  upon  that  organ.  It  is  evident, 
besides,  that  distension  of  the  stomach  chiefly  affects  its  great  curvature. 

The  peritoneal  coat  does  not  adhere  firmly  to  the  subjacent  tissues  of  the  stomach,  in 
the  neighbourhood  of  either  curvature ;  but  it  is  closely  united  to  them  at  the  middle  points 
of  both  surfaces.  The  imperfect  extensibility  of  the  peritoneal  coat  requires  such  an  ar- 
rangement as  exists  along  the  curvatures.  I  have  observed  some  small  fibrous  bands 
in  the  sub-serous  cellular  tissue  along  the  lesser  curvature,  which  must  be  intended  to 
maintain  the  shape  of  that  part.  The  uses  of  the  peritoneal  coat,  in  reference  to  the 
stomach  itself,  are  merely  mechanical ;  it  strengthens,  preserves  the  shape,  and  facili- 
tates the  movements  of  this  organ. 

The  Muscular  Coat. — This  coat  has  engaged  much  of  the  attention  of  anatomists  since 
the  time  of  Fallopius,  who  was  the  first  to  give  a  correct  description  of  it ;  and  to  whom 
Morgagni  {Advers.  Anat.,  iii.,  p.  6)  has^ttributed  the  honour  of  discovering  it,  in  opposi- 
tion to  the  claims  of  Willis.  Helvetius  made  it  the  subject  of  a  special  work  {Hist. 
Acad.  Roy.  des  Sciences,  1719). 

We  shall  describe,  in  accordance  with  Haller  (Elem.  Phys.,  tom.  vi.,  lib.  xix.,  sect,  i., 


Fig.  161. 


p.  126),  and  the  majority  of  anatomists,  three  layers  of  muscu- 
lar fibres. 

The  superficial  or  longitudinal  layer  (1,  fig:  151)  is  formed  by  a 
continuation  of  the  longitudinal  fibres  of  the  oesophagus,  whioh 
spread  out  in  a  radiated  manner  from  the  cardiac  orifice  of  the 
stomach.  They  are  scattered  thinly  over  its  surfaces,  the  great 
curvature,  and  the  great  extremity,  but  are  collected  into  a  band 
along  the  lesser  curvature,  the  shape  of  which  they  assist  in 
preserving.  On  account  of  this  arrangement,  they  have  re- 
ceived the  name  of  cravatc  de  Suisse. 

These  fibres  form  a  continuous  plane  of  considerable  thick- 
ness over  the  contracted  portion  of  the  stomach,  near  the  pylo- 
rus. In  this  situation  they  are  stronger,  and  fasciculated,  and 
appear  partly  to  terminate  in  the  pyloric  constriction,  and  part- 
ly to  be  continued  upon  the  duodenum. 

The  second  or  circular  layer  (2,  fig.  151)  is  composed  of  fibres 
which  cross  the  axis  of  the  stomach  at  right  angles,  so  as  to 
form  a  succession  of  rings  from  the  oesophagus  to  the  pylorus. 
They  are  few  in  number  at  the  great  extremity  of  the  stomach, 
but  become  much  more  numerous  towards  the  pylorus,  through- 
out all  the  contracted  portion  of  the  stomach.  At  the  pylorus 
itself  they  form  a  thick  ring,  which  forms  a  sort  of  rim,  project- 
ing in  the  interior.     I  have  always  found  this  more  developed 


THE    STOMACH.  357 

in  old  age  than  at  any  other  period  of  life.  It  is  a  true  sphincter,  which,  by  its  contrac- 
tion, effectually  opposes  the  passage  of  food  and  gas  from  the  stomach  into  the  duode- 
num. It  is  not  uncommon  to  find  the  whole  of  this  ring,  or  a  half,  or  two  thirds  of  it,  in- 
creased to  the  thickness  of  three  or  four  lines,  independently  of  any  organic  lesion. 

The  older  anatomists  admitted  also  an  oesophageal  ring  (or  (esophageal  sphincter),  simi- 
lar to  that  at  the  pylorus,  and  having  the  power  of  closing  the  oesophageal  orifice.  This, 
however,  does  not  exist ;  the  last  circular  fibres  of  the  oesophagus  do  not  form  a  thicker 
layer  than  the  others. 

Lastly,  the  different  rings  formed  by  the  circular  fibres  of  the  stomach  intersect  each 
other  obliquely  at  very  acute  angles.  The  spired  arrangement  admitted  by  Santorini 
cannot  be  demonstrated. 

The  third  muscular  layer  (3,  fig.  151),  which  I  have  only  been  able  to  see  distinctly  upon 
hypertrophied  stomachs,  is  composed  of  looped  or  parabolic  fibres,  the  middle  portions  of 
which  embrace  the  great  end  of  the  stomach,  extending  from  the  left  side  of  the  cardiac 
orifice  obliquely  downward  towards  the  great  curvature,  while  their  anterior  and  posterior 
extremities  are  situated  upon  the  corresponding  surfaces  of  this  viscus.  The  superior 
loops  reach  the  lesser  curvature,  the  inferior  the  great  curvature,  and  the  intermediate 
loops  seem  to  be  lost  upon  either  surface,  or,  rather,  to  become  blended  with  the  circu- 
lar fibres.  This  layer  of  fibres  appears  intended  to  compress  the  great  extremity  of  the 
stomach,  and  to  push  the  food  into  the  body  of  the  organ,  towards  the  pylorus. 

From  what  has  been  stated,  it  follows  that,  excepting  in  the  vicinity  of  the  pylorus, 
the  muscular  layers  of  the  stomach  do  not  form  a  continuous  plane,  but  have  an  areolar 
disposition :  the  areolae,  or  spaces  between  the  different  fibres,  are  of  considerable  size ; 
hence  the  necessity  for  a  strong  membrane,  like  the  fibrous  coat,  which,  as  we  shall 
find,  constitutes  the  framework  of  the  stomach. 

The  muscular  fibres  of  the  several  layers  are  much  paler  than  those  of  the  oesopha- 
gus.* They  have  a  pearly  appearance  when  seen  through  the  peritoneal  coat,  which 
has  led  to  the  supposition  that  they  are  tendinous.  Hence  the  error  of  Helvetius,  Wins- 
low,  and  others,  who  regarded  the  two  white  lines  running  along  the  two  surfaces  of  the 
stomach,  between  the  curvatures,  as  ligaments  of  the  pylorus ;  they  are  nothing  more 
than  longitudinal  muscular  fibres.  Other  authors  have  merely  admitted  some  tendinous 
intersections  of  these  fibres. 

The  muscular  coat  is  not  uniformly  thick  at  all  points.  It  is  very  thin  at  the  great 
cul-de-sac,  and  becomes  much  thicker  towards  the  pylorus.  It  also  presents  many  va- 
rieties in  different  subjects ;  it  is  but  slightly  developed  in  large  stomachs,  and  much  more 
so  when  this  organ  is  contracted.  There  is  a  physiological  as  well  as  a  pathological  hy- 
pertrophy of  the  muscular  coat.     In  the  latter  it  has  been  found  seven  or  eight  lines  thick. 

The  Fibrous  Coat. — This  coat,  the  existence  of  which  has  been  alternately  admitted 
and  denied,  is  situated  between  the  muscular  and  the  mucous  coats,  and  is  quite  distinct 
from  both.  It  was  known  by  the  ancients  as  the  membrana  nervosa  ,•+  it  constitutes, 
properly  speaking,  the  frcmiework  of  the  organ.  In  order  to  demonstrate  this  coat,  it  is 
sufficient  to  remove  the  peritoneal  and  muscular  tunics,  and  then  to  evert  the  stomach 
and  remove  the  mucous  membrane.  This  experiment  will  also  very  clearly  show  the 
great  strength  of  the  fibrous  coat,  which,  even  thus  unsupported,  can  bear  considerable 
distension ;  while,  on  the  other  hand,  when  this  coat  has  been  divided,  the  remaining 
membrane  or  membranes  burst  through  the  opening  thus  made. 

This  coat  should  not  be  confounded  with  the  dermis  of  the  mucous  membrane,  for  it 
adheres  much  more  strongly  to  the  muscular  coat,  into  which  it  sends  numerous  pro- 
longations, than  to  the  mucous  membrane,  with  which  it  is  connected  only  by  loose  cel- 
lular tissue. 

The  fibres  of  this  coat  have  not  a  parallel  arrangement  like  those  of  aponeuroses  and 
fibrous  sheaths,  but  they  form  a  very  dense  network,  the  filaments  or  lamellae  of  which 
can  be  separated  by  inflation  or  infiltration.  It  is  concerned  in  a  very  important  man- 
ner in  chronic  diseases  of  the  stomach ;  it  is  very  liable  to  hypertrophy  ;  and,  in  certain 
cases,  acquires  a  thickness  of  several  lines. 

The  Mticous  Membrane. — The  history  of  this  membrane  is  curious.  It  was  for  a  long 
time  confounded  with  the  mucus  by  which  it  is  covered,  being  regarded  as  merely  a  dried 
layer  of  that  secretion.J  It  was  pointed  out  by  Fallopius,  who  applied  to  it  the  very  ap- 
propriate appellation  of  the  velvet-like  tunic ;  but  it  was  first  described  as  a  separate  mem- 
brane by  Willis,  under  the  title  of  the  glandular  tunic.  The  discovery  was  confirmed  by 
the  beautiful  injections  of  Ruysch,  who  gave  it  the  name  of  epithelium ;  to  which  term, 
however,  he  did  not  attach  the  same  meaning  as  modern  authors.  It  was  afterward  re- 
garded as  an  epidermic  membrane,  analogous  to  the  epidermis  of  the  skin,^  and  capable 

*  [Thejr  are  principally  of  the  involuntary  class,  but  have  a  few  striated  fibres  among-  them  (see  note,  p.  3  JJ 

t  [So  called  from  its  white  appearance.] 

X  Riolanus  states  positively  {Anthropol,  1.  ii.,  c.  xii.,  p.  171)  that  the  stomach,  like  the  intestines,  is  com- 
posed of  three  coats,  viz.,  a  common  external  membrane,  a  nervous,  and  a  muscular  coat;  and  that  a  closely 
adherent  mucus,  consisting  of  the  thickest  part  of  the  chyle,  lines  it  on  the  inside. 

t)  Such  was  the  opinion  of  Ilaller,  lib.  xix.   p.  132. 


358  SPLANCHNOLOGY. 

of  being  thrown  off  and  renewed.  In  recent  times  it  has  been  supposed  to  be  concerned 
tanquam  omnium  lerna  malorum,  and  has  become  in  the  present  day  the  object  of  a  great 
number  of  most  interesting  researches. 

The  mucous  membrane  of  the  stomach  presents  an  adherent  and  a  free  surface.  The 
adherent  surface  is  united  to  the  fibrous  coat  by  cellular  tissue,  so  loose  as  to  permit  very 
free  motions.  The  free  surface  has  the  following  characters  :  When  the  stomach  is 
strongly  contracted,  it  forms  a  number  of  folds  (see^^.  150),  the  principal  of  which  are 
longitudinal ;  these  folds  disappear  when  the  organ  is  distended,  as  may  be  shown  in  an 
everted  stomach.  Their  only  use  is  to  allow  of  the  rapid  distension  of  this  organ,  a  con- 
dition that  could  not  have  been  attained  in  any  other  mode,  in  consequence  of  the  slight 
elasticity  of  the  mucous  coat. 

These  longitudinal  and  temporary  folds,  which  are  perfectly  distinct  from  the  perma- 
nent folds  observed  in  other  parts  of  the  alimentary  canal,  are  most  strongly  marked 
near  the  pyloris ;  they  are  extremely  regular,  sometimes  straight  and  sometimes  flexu- 
ous  ;  and  they  proceed  parallel  to  each  other  from  the  cardiac  towards  the  pyloric  orifice 
They  are  intersected  more  or  less  obliquely  by  other  winding  folds  of  different  degrees, 
which  often  give  an  areolar  appearance  to  the  internal  surface  of  the  stomach. 

From  this  arrangement,  it  follows  that  dilatation  of  the  stomach  occurs  principally  in 
a  direction  across  its  long  axis  ;  the  resources  for  dilatation  in  the  direction  of  its  axis 
are  much  less  numerous.  Of  all  the  folds  of  the  mucous  membrane,  the  most  important 
is  undoubtedly  that  called  the  pyloric  valve,  which  is  often  nothing  more  than  a  mere 
elevation  of  the  membrane  by  the  sphincter  muscle.*  This  cellular  fold  is  equally  op- 
posed to  the  regurgitation  of  food  from  the  duodenum  into  the  stomach,  and  to  its 
passage  from  the  stomach  into  the  duodenum ;  it  is  completely  effaced  by  distension, 
and  it  belongs  as  much  to  the  duodenum  as  to  the  stomach.  Its  upper  half  has  the 
characters  of  the  gastric ;  the  lower  half  offers  those  of  the  duodenal  mucous  membrane. 
Diseases  are  sometimes  observed  to  stop  at  the  line  of  separation.  We  may  add,  that 
the  folds  upon  the  internal  surface  of  the  stomach  are  formed  by  the  mucous  membrane 
alone  ;  the  fibrous  coat  does  not  enter  into  them. 

Besides  these  folds,  the  mucous  membrane  presents  numerous  slight  and  tortuous 
furrows,  dividing  it  into  small  spaces  or  compartments,  which  are  either  lozenge-shaped, 
hexagonal,  polygonal,  circular,  oblong,  or  irregular. 

Examined  by  the  naked  eye,  the  mucous  membrane  has  a  soft,  spongy,  tomentose,  or 
velvety  appearance  ;  hence  the  name  of  villous  or  velvet-like  membrane,  by  which  it  is  still 
generally  known.  It  is  covered  by  a  layer  of  mucus  of  variable  thickness,  which  may 
be  detached  by  friction  with  a  coarse  cloth.  In  order  to  avoid  the  inconveniences  arising 
from  this  method,  which  is  more  or  less  injurious  to  the  texture  of  the  membrane,  I  have 
been  accustomed  to  use  a  gentle  stream  of  water,  which,  at  the  same  time  that  it  com- 
pletely washes  away  the  mucus,  clearly  displays  the  papillary  structure  of  the  surface 
of  the  membrane. 

There  are  some  stomachs  which  might  be  called  granular  or  glandjtlar,  because  the 
mucous  membrane  has  a  granular  appearance,  so  that  at  first  sight  it  might  be  imagined 
that  some  small  glandular  bodies  (like  the  salivary  glands)  were  scattered  over  the  in- 
ternal surface  of  the  stomach  ;  but  this  glandular  aspect  is  merely  apparent,  depending 
upon  the  circular  or  semicircular  direction  of  the  furrows  in  the  mucous  membrane, 
which  give  a  spheroidal  character  to  the  kind  of  islets  that  are  intercepted  between  them. 
This  gi'anular  appearance  is  seldom  observed  over  the  entire  stomach  ;  it  rarely  exists 
at  the  great  extremity.  I  have  found  it  limited  to  the  great  curvature  ;  most  frequently 
it  occurs  in  the  vicinity  of  the  pylorus ;  sometimes  it  is  observed  over  all  that  part  of  the 
stomach  which  is  to  the  right  of  the  oesophagus.  These  granulations  are  particularly 
developed  in  the  stomach  of  the  pig. 

There  is  one  remark  upon  which  too  much  importance  cannot  be  placed  ;  and  that  is, 
the  difference  in  the  appearance  of  the  mucous  membrane  of  the  great  extremity  of  the 
stomach,  and  of  the  part  situated  to  the  right  of  the  oesophagus.  Sometimes  the  line  of 
separation  forms  a  perfect  circle  ;  and  this  is  a  very  remarkable  fact,  because  in  man, 
who  has  a  single  stomach,  it  may  be  considered  as  a  rudiment  of  the  division  into  the 
compound  stomachs  found  in  the  lower  animals  ;  for  a  multiple  stomach  results  rather 
from  some  difference  in  the  structure  of  the  mucous  membrane,  than  from  the  existence 
of  different  compartments  or  distinct  cavities.  It  will  not  be  uninteresting  to  connect 
this  remark  with  what  has  been  already  stated  regarding  bilocular  stomachs. 

We  shall  now  examine  the  characters  of  the  mucous  membrane  in  the  oesophageal  and 
in  the  pyloric  portion  of  the  stomach. 

In  the  oesophageal  portion  it  is  thinner,  softer,  and  more  vascular,  and  can  only  be 
separated  in  flakes  from  the  subjacent  parts.  When  the  stomach  contains  any  liquid 
after  death,  this  part  is  converted  into  a  sort  of  pulp,  which  becomes  of  a  blackish  colour, 
from  the  action  of  the  acids  in  the  gastric  fluid  upon  the  blood  contained  in  the  vessels 
of  the  stomach.    This  is  the  pultaceous  softening,  which  I  regard  as  a  post-mortem  change, 

*  [It  usually  consists  of  the  mucous  membraue,  the  cellular  coat,  and  the  circular  muscular  fibres.] 


THE   STOMACH.  359 

but  which  has  been  erroneously  confounded  with  the  gelatiniform  softening.  I'his  second 
portion  of  the  mucous  membrane,  i.  e.,  the  part  situated  to  the  right  of  the  oesophagus, 
is  thicker,  stronger,  and  whiter,  and  may  be  separated  entire  from  the  other  coats.  Dis- 
eases often  observe  the  line  of  separation  between  the  right  and  the  left  portions  of  the 
stomach. 

Modern  pathologists  having  attached  great  importance  to  the  condition  of  the  gastric 
mucous  membrane,  it  has  become  highly  interesting  to  determine  its  characters  in  the 
healthy  state  ;  these  characters  relate  to  its  colour,  its  consistence,  and  its  thickness. 

Colour. — It  is  extremely  difficult  to  determine  what  is  the  natural  colour  of  this  mucous 
membrane.  The  opinion  generally  maintained  by  the  best  authorities,  that  it  is  either 
primarily  or  secondarily  affected  in  the  majority  of  diseases,  compels  us  to  reject  all  ob- 
servations made  upon  persons  who  have  died  from  acute  or  chronic  diseases,  or  even 
from  wounds  or  injuries  of  long  standing.  We  are,  therefore,  obliged  to  have  recourse 
to  cases  of  accidental  death  in  persons  previously  in  health.  In  such  cases,  for  example, 
in  criminals  who  are  executed  while  the  stomach  is  empty,  the  mucous  membrane  is 
found  of  a  grayish-white  colour,  with  a  slight  tint  of  yellow  and  pink.*  When  death  has 
occurred  during  digestion,  the  mucous  membrane  is  found  to  vary  from  a  delicate  pink 
to  the  most  vivid  red.  After  putrefaction  has  made  some  little  progress,  we  find  a  red 
or  port  wine  colour,  or  a  brownish  black  tint  prevailing  over  the  great  extremity  of  the 
stomach,  and  at  the  free  edges  of  the  folds  or  wrinkles  to  which  the  vessels  correspond  ; 
again,  it  is  often  found  marked  with  blackish  patches,  or  marbled  ;  but  these  discolora- 
tions  are  the  result  of  post-mortem  transudation. 

In  the  pultaceous  and  blackish  softening  of  the  mucous  membrane,  the  colour  is  owing 
to  the  action  of  the  acids  in  the  gastric  juice.  Wlien  the  stomach  contains  bile,  the  mu- 
cous membrane  is  tinged  with  yellow  or  green,  and  the  stain  sometimes  remains  after 
the  longest  maceration. 

If  the  mucous  membrane  be  rubbed  with  a  rough  cloth,  so  long  as  the  vessels  contain 
blood,  we  may  produce  a  red  punctuated  appearance,  which  has  been  often  mistaken  for 
a  sign  of  inflammation.  Lastly,  in  the  aged  we  not  unfrequently  observe  a  slate  gray 
colour,  either  in  points  or  in  patches,  or  diffused  over  the  surface.  This  colour  occupies 
the  papillae,  and  may  afford  proof  of  some  former  irritation,  but  is  certainly  not  due  to  any 
diseased  action  during  the  later  periods  of  life.  These  different  discolorations  of  the 
stomach  must  not  be  confounded  with  the  alterations  in  its  colour  resulting  from  disease. 

Thickness. — It  is  difficult  to  estimate  the  exact  thickness  of  the  gastric  mucous  mem- 
brane. Like  the  muscular  coat,  it  varies  in  different  individuals  ;  in  chronic  inflamma- 
tion it  is  twice  or  three  times  its  natural  thickness.  In  determining  the  thickness  of  this 
membrane,  it  is  important  to  bear  in  mind  the  difference  in  this  particular  between  the 
oesophageal  and  pyloric  portions  ;  the  former  being  extremely  thin,  and  the  latter  twice 
or  three  times  as  thick  as  that. 

Consistence. — The  same  remarks  apply  to  its  consistence,  for  there  are  many  individ- 
ual varieties  in  this  respect.  The  oesophageal  portion  may  be  torn  with  great  ease  ;  but 
the  pyloric  portion  is  so  dense,  that  the  back,  and  even  the  edge  of  a  scalpel,  may  be 
drawn  over  it  with  considerable  force  without  wounding  it.  If  there  has  been  any  liquid, 
or  even  food  in  the  stomach,  in  however  small  quantity,  the  mucous  membrane  of  the 
oesophageal  portion,  when  macerated,  is  converted  into  a  pulp ;  moderate  distension  will 
then  rupture  the  weills  of  the  stomach,  which  may  be  broken  through  by  the  point  of  the 
finger. 

From  want  of  sufficient  reflection  upon  this  subject,  men  of  great  merit  have  commit- 
ted serious  errors  in  the  appreciation  of  morbid  lesions.  In  the  gelatiniform  softening, 
the  gastric  mucous  membrane,  as  well  as  the  other  coats  of  the  stomach,  become  dis- 
solved, and  resemble  a  solution  of  gelatine.  In  many  old  people,  and  in  some  adults,  I 
have  found  the  mucous  membrane  so  thick  and  so  strong,  that  it  could  be  dissected  off 
entire,  and  removed  in  one  piece.  This  condition  coexisted  with  the  slate  colour,  either 
accompanied  or  not  with  chronic  inflammation. 

The  PapillcB. — If  we  examine  the  mucous  membrane  of  the  stomach,  placed  under  wa- 
ter, and  exposed  to  the  direct  rays  of  the  sun  by  the  aid  of  a  powerful  lens,  we  shall  find 
that  its  surface  is  very  irregular,  mammillated.  Fig.  152.  Fig.  153. 
and  furrowed,  so  as  to  present  an  appearance  very 
like  the  convolutions  of  the  small  intestine.  The 
eminences,  which  are  much  more  distinct  to- 
wards the  pylorus  than  near  the  oesophagus,  are 
studded  with  holes,  or,  rather,  with  small  pits 
resembling  the  cells  of  a  honeycomb  (figs.  152, 
153).  These  alveolar  depressions  are  well  de- 
scribed by  Home,  who  states  that  they  exist  only  r-im  -tj^an— « 

in  the  great  cul-de-sac,  while  the  viUi  occupy  the  ""'il^fi  J32  a.aB.rt^!'      ^^S^S^toT 

*  In  a  great  number  of  individuals  who  have  died  from  acute  or  chronic  diseases,  the  gastric  mucous  mem- 
brane is  found  in  the  same  state  as  in  those  who  have  died  accidentally  ;  it  is,  therefore,  not  always  affectedi 
either  primarily  or  secondarily,  in  disease 


360  SPLANCHNOLOGY. 

rest  of  the  stomach.  The  truth  is,  that  a  precisely  similar  stmcture  is  observed  ovei 
the  whole  stomach.  The  alveoli,  or  pits,  are  separated  from  each  other  by  small  pro- 
jections, or  papilla  {fig.  153),  of  vi^hich  the  papillae  of  the  tongue  convey  an  excellent  idea.* 

Should  these  papillae  be  distinguished  from  other  projections  that  have  been  termed 
villi,  by  Ruysch,  for  example,  who  called  the  entire  membrane  villoso-papillaris  ?  Aftei 
the  most  minute  examination,  I  have  only  detected  one  order  of  eminences,!  viz.,  the 
papilla,  the  existence  of  which  I  regard  as  the  essential  character  of  all  tegumentary 
membranes,  whether  mucous  or  cutaneous,  which  might  all,  therefore,  be  designated 
papillary  membranes.     We  shall  return  again  to  the  structure  of  the  papillse. 

If  we  examine  with  a  lens  or  simple  microscope  a  perpendicular  or  oblique  section 
of  the  mucous  membrane  of  the  stomach,  we  shall  perceive  that  it  consists  essentially  of 
a  strong  membrane,  the  mucous  dermis,  from  which  arise  an  immense  number  of  small 
eminences  closely  pressed  together,  and  of  unequal  lengths,  like  the  pile  of  velvet. 
These  eminences  are  the  papillae  ;  they  are  liable  to  great  enlargement  in  cases  of  hy- 
pertrophy, and  then  the  structure  just  described  becomes  very  apparent. 

The  Follicles. — The  follicles  of  the  stomach  can  be  very  easily  demonstrated  in  the 
pigt  and  in  the  horse.  In  the  last-mentioned  animal,  entozoa  are  frequently  found  in 
the  centre  of  these  follicles,  which  then  become  developed  into  hard,  and  sometimes 
very  large  tumours.  It  is  so  difficult  to  demonstrate  them  in  the  human  subject,  that, 
with  most  anatomists,  I,  for  a  long  time,  doubted  their  existence.  Haller  only  saw  them 
once  or  twice  ;^  but  in  some  individuals  they  are  very  distinct.  I  found  them  well 
marked  in  a  great  number  of  cholera  patients.  II  They  are  not  situated  in  the  sub-mucous 
cellular  tissue,  as  is  generally  stated,  but  in  the  substance  of  the  membrane  itself,  so  as 
to  form  a  projection  on  the  inside  of  the  stomach,  but  not  on  the  outer  surface.  They 
are  rounded,  flattened,  and  perforated  by  a  central  foramen,  which  is  usually  visible  to 
the  naked  eye.  I  have  observed  them  upon  all  points  of  the  mucous  membrane,  but  they 
appear  to  be  most  numerous  near  the  oesophageal  orifice,  and  along  the  lesser  curvature. IT 

The  Vessels  and  Nerves  of  the  Stomach. — The  arteries  are  very  large  and  numerous  in 
proportion  to  the  size  of  the  stomach  ;  they  must,  therefore,  assist  in  the  performance 
of  some  function  besides  the  mere  nutrition  of  the  organ  ;  this  function  is  the  secretion 
of  the  gastric  juice.  They  all  arise  from  the  cceliac  axis,  and  are  the  coronary,  the  su- 
perior pyloric  and  right  gastro-epiploic  branches  of  the  hepatic,  and  the  left  gastro-epi- 
ploic  and  vasa  brevia,  which  are  branches  of  the  splenic  artery.  These  arteries  anas- 
tomose, so  as  to  form  around  the  stomach  a  vascular  zone,  which  is  in  close  contact 
with  that  organ  during  distension,  but  at  some  distance  from  it  when  empty.  From  this 
arterial  circle  branches  are  given  off,  which  at  first  lie  between  the  peritoneal  and  the 
muscular  coats,  but,  after  a  certain  number  of  divisions  and  anastomoses,  perforate  the 
muscular  and  fibrous  coats,  and  again  subdivide  and  anastomose  a  great  number  of  times 
in  the  loose  sub-mucous  cellular  tissue,  until,  having  become  capillary,  they  penetrate  the 
mucous  membrane. 

The  veins  bear  the  same  name,  and  follow  the  same  direction  as  the  arteries  ;  they 
contribute  to  form  the  vena  portae.  Schmiedel  (Variet.  Vasorum,  No.  xix.,  p.  26)  has 
seen  the  coronary  vein  of  the  stomach  anastomose  with  the  renal  vein,  the  pyloric  with 
the  vena  azygos,  and  one  of  the  venae  breves  with  the  phrenic  vein. 

The  lymphatic  vessels  are  very  numerous,  and  terminate  in  the  lymphatic  glands,  situ- 
ated along  the  two  curvatures  of  the  stomach.  The  peculiar  ducts,  said  to  proceed  from 
the  spleen  to  the  stomach,  and  supposed  by  the  ancients  to  be  passages  for  the  atra  bilis, 
are  purely  imaginary. 

The  nerves  are  of  two  kinds,  some  being  derived  from  the  eighth  pair,  and  others  from 
the  solar  plexus. 

The  nerves  of  the  eighth  pair  form  a  plexus  around  the  cardiac  orifice,  the  left  nerve 
being  distributed  upon  the  anterior,  and  the  right  upon  the  posterior  surface  of  the  stom- 

*  [The  alveoli  are  from  t^tt'^  '■°  oTo*^  °^  ^^  inch,  and,  near  the  pylorus,  y^n^th  of  an  inch  in  diameter. 
At  the  bottom  of  each  alveolus  is  seen  a  group  of  minute  apertures  (fig.  152),  which  are  the  open  mouths  of 
small  tubes  placed  perpendicularly  to  the  surface  of  the  membrane,  and  closed  at  the  other  end.  In  a  vertical 
section  of  the  membrane,  these  tubes,  which  average  about  -jijyth  of  an  inch  in  diameter,  are  seen  to  rest  upon 
the  sub-mucous  tissue  by  their  closed  extremities.  In  the  cardiac  portion  of  the  stomach  they  are  short  and 
stiuight ;  near  the  pyloric  end  they  are  longer,  and  convoluted,  or  irregularly  dilated,  and  are  sometimes  bifur- 
cated. Bloodvessels  pass  up  between  these  tubes,  and  form  a  capillary  network  round  the  borders  of  the  al- 
veoli. The  membranous  projections  sometimes  found  between  the  alveoli  {fig.  153)  form  irregular  fringes, 
broader  than  the  lingual  papillae,  and  seem  rather  to  be  imperfectly  developed  villi  (see  note,  p.  361),  and  are 
usually  so  called.  The  epithelium  covering  the  entire  mucous  membrane  of  the  stomach  consists  of  a  single 
layer  of  minute  columnar  cells  ;  it  is  very  delicate,  and  invisible,  except  by  a  high  magnifying  power ;  hence 
its  existence  was  formerly  denied.] 

t  Upon  this  subject  see  the  Memoir  of  Helvetius.— (/Tj'ii.  Acad.  Roy.  des  Sciences,  1720.) 

t  [In  the  pig  these  follicles  appear  to  be  nothing  more  than  prolongations  of  the  mucous  membrane,  or 
small  diverticula;  so  that,  after  having  detached  the  mucous  membrane,  they  may,  by  slight  pressure,  be 
turned  inside  out.] 

t>  "  Neque  rejici  debent,  etsi  non  semper  possint  ostendi." — (Haller,  1.  vi.,  lib.  xix.,  p.  140.) 

II  Vide  Anat.  Path,  avec  planches,  liv.  xiv.,  pi.  1. 

IT  [In  the  neighbourhood  of  the  (esophageal  orifice  there  are  also  several  small  cgmpound  glands,  analogous 
to  Brunner's  glands  in  the  duodenum. — (W.  S.)] 


THE   INTESTINES.  36] 

ach.  They  may  be  followed  as  far  as  the  muscular  coat,  where  they  seem  to  be  lost , 
division  of  them  paralyzes  this  coat.  By  means  of  the  nerves  of  the  eighth  pair,  the 
stomach  is  connected  with  the  oesophagus,  the  lungs,  the  pharynx,  the  larynx,  and'  the 
heart.  Through  the  nerves  derived  from  the  central  epigastric  plexus,  and  named  after 
the  arteries  that  support  them,  the  stomach  is  connected  with  the  ganglionic  system 
and  is  brought  into  relation  with  the  numerous  viscera  of  the  abdomen. 

Lastly,  a  very  delicate  serous  cellular  tissue  unites  the  different  coats  of  the  stomach. 
There  are  three  layers  of  this  tissue,  viz.,  one  between  the  peritoneal  and  the  muscular 
coats,  another  between  the  muscular  and  the  fibrous,  and  a  third  between  the  fibrous 
and  the  mucous  coats.  The  last  of  these  is  the  most  distinct ;  it  is  liable  to  both  serous 
and  sanguineous  effusions,  and  may  become  the  seat  of  diffuse  inflammation.  I  have 
lately  seen  it  infiltrated  with  pus  to  a  considerable  extent,  the  mucous  and  the  fibrous 
coats  being  both  perfectly  healthy. 

Develcypment  of  the  Stomach. — The  stomach  of  the  foetus  is  remarkable  on  account  of 
its  vertical  position,  which  is  due  to  the  great  development  of  the  liver,  especially  of  its 
left  lobe.  An  unnatural  development  of  that  lobe  will  also  occasion  a  similar  position 
of  the  stomach  in  the  adult.  The  relative  smallness  of  the  stomach,  and  the  slight  de- 
velopment of  its  tuberosity,  are  also  characteristic  of  its  foetal  condition.*  Nevertheless, 
from  the  first  moment  of  its  appearance,  it  is  distinguished  from  the  rest  of  the  aliment- 
ary canal  by  its  greater  size.  The  changes  which  the  adult  stomach  undergoes,  and 
the  variations  in  size  which  it  presents,  are,  perhaps,  less  dependant  upon  congenital 
differences  than  upon  particular  habits.  The  differences  in  the  two  sexes  are  manifest- 
ly due  to  the  pressure  to  which  the  stomach  of  the  female  is  subject,  either  from  the  use 
of  stays  or  from  the  gravid  uterus.  I  may  here  advert  to  the  development  of  the  mus- 
cular ring  of  the  pylorus,  and  of  the  neighbouring  part  of  the  stomach  in  aged  persons. 

Function. — The  stomach  is  the  organ  of  chymification,  or  of  that  process  by  which  the 
food  is  converted  into  a  homogeneous  gray  pulp,  called  chyme.  For  that  purpose  it  is 
evidently  necessary  that  the  food  should  remain  for  some  time  in  this  organ,  and  the 
elasticity  of  the  muscular  coat  of  the  oesophagus  and  of  the  ring  at  the  pylorus  are  suffi- 
cient to  prevent  its  regurgitation  into  the  gullet,  or  its  passage  into  the  duodenum. 
When  the  process  is  completed,  however,  the  peristaltic  contraction  of  the  muscular 
fibres  of  the  stomach  overcomes  the  resistance  of  the  pylorus  ;  in  eructation,  regurgita- 
tion, and  vomiting,  the  same  peristaltic  movements  are  assisted  by  the  contraction  of 
the  diaphragm  and  the  abdominal  muscles. 

Chymification  is  a  chemical,  or,  at  least,  a  molecular  action,  and  is  effected  by  means 
of  the  gastric  juice,  mixed  with  the  salivary  and  oesophageal  secretions.  These  fluids 
are  acid.t 

The  influence  of  the  nerves  upon  digestion  has  been  ascertained  by  ingenious  experi- 
ments, the  results  of  which,  however,  have  been  interpreted  in  various  ways. 

The  Intestines  in  general. 
The  term  intestine,  in  its  widest  signification,  is  applied  to  the  whole  alimentary  ca- 
nal ;  but,  in  a  more  limited  sense,  it  means  that  long  and  frequently-convoluted  tube, 
extending  from  the  pylorus  to  the  anus,  and  occupying  almost  the  whole  of  the  abdomi- 
nal cavity.  The  intestines  have  been  divided,  according  to  their  calibre,  into  the  small 
{b  to  d,Jig.  139)  and  the  large  (c  to  i) ;  this  distinction,  which  is  applicable  to  most  ani- 
mals, is  anatomically  established  in  man  by  a  difference  in  size,  by  the  sacculated  char- 
acter of  the  large  intestine,  by  a  difference  in  direction,  by  the  presence  of  a  valve,  by 
the  existence  of  a  caecum  and  of  a  vermiform  appendix,  and,  lastly,  by  a  difference  in 
structure,  especially  in  the  muscular  and  mucous  coats.  Tlie  same  distinction  is  recog 
nised  in  physiology,  and  upon  equally  good  grounds,  for  the  small  intestine  is  essentid- 
ly  concerned  in  the  formation  and  absorption  of  the  chyle,  while  the  large  intestine  is  the 
organ  of  defsecation.J  These  differences  will  be  rendered  more  apparent  from  the  de 
scription  of  these  two  important  parts  of  the  alimentary  canal. 

The  Small  Intestine. 
The  small  intestine  includes  all  that  part  which  is  situated  between  the  stomach  and 
the  large  intestine  (i  to  d,fig.  139).  According  to  Haller,  Bichat,  and  their  followers, 
the  upper  portion,  called  the  duodenum  (b  to  c),  should  be  abstracted  from  the  small  in- 
testine, which,  according  to  them,  would  commence  at  the  termination  of  the  duodenum. 
It  appears  to  me  that  the  former  definition  should  be  adhered  to,  on  account  both  of  the 

*  [At  early  periods  of  foetal  life,  villi  are  found  on  the  mucous  membrane  of  the  stomach  g-enerally,  after- 
ward on  the  pyloric  portion  only  ;  and,  subsequently  to  birth,  the  only  traces  of  these  are  the  irregular  frmgcB 
observed  here  and  there  between  the  alveoli.] 

t  [The  saliva,  though  sometimes  acid,  is  usually  alkaline.] 

i  The  division  into  a  small  and  large  intestine  exists  among  all  vertebrated  animals  ;  but  no  animals,  ex- 
cepting the  ourangs  and  the  wombat,  have  both  a  ciecum  and  an  appendix  vermiformis.  In  some  we  find  one 
caecum,  or  several  caeca  ;  in  others,  one  or  more  vermiform  appendices  ;  others  have  neither  csecum  nor  appen- 
dix, but  a  valvular  fola  arit  a  well-marked  change  in  diameter  indicate  the  limit  between  the  small  ana  larf« 
intestines.     In  some,  again,  the  only  difference  consists  in  a  change  of  diameter. 

Zz 


9m 


SPLANCHNOLOGY. 


absence  of  any  real  line  of  separation  between  the  duodenum  and  the  rest  of  the  small 
intestine,  and  of  their  similarity  in  structure  and  function. 

The  small  intestine  is  divided  into  three  parts,  the  duodenum,  the  jejunum,  and  the 
ileum.  The  division  between  the  duodenum  and  the  rest  of  the  small  intestine  is  defi- 
nite, but  that  between  the  jejunum  and  the  ileum  is  altogether  arbitrary ;  so  that  we 
shall  follow  the  example  of  Haller,  Scemmering,  and  others,  in  describing  the  jejunum 
and  ileum  together  (c  to  d),  under  the  name  of  the  small  intestine,  properly  so  called. 

The  Duodenum. 
Dissection. — ^When  the  abdomen  is  opened,  the  first  portion  only  of  this  intestine  is 
visible  ;  the  second  is  hid  by  the  ascending  colon  ;  the  third  is  seen  in  the  cavity  of  the 
omentum.  The  second  is  brought  into  view  by  turning  aside  the  colon.  The  third  por- 
tion, which  is  the  most  difficult  to  demonstrate,  may  be  exposed  in  two  ways  :  either  by 
cutting  through  the  inferior  layer  of  the  transverse  mesocolon,  or  by  turning  the  stomach 
upward,  after  having  divided  the  lavers  of  the  grest  omentum,  which  are  attached  along 
its  greater  curvature. 

Fig- 154.  The    duodenum  {dudsKa 

6uKTvXov,  p  b,  Jig.  154),  so 
called  by  Herophilus  (Ga- 
len, Administr.  Ariat.,  lib. 
vi.,  c.  9)  on  account  of  its 
being  about  equal  in  length 
to  the  breadth  of  twelve  fin- 
gers, commences  at  the  py- 
lorus, and  terminates,  with- 
out any  precise  line  of  de- 
marcation, to  the  left  of  the 
second  lumbar  vertebra,  at 
the  point  where  the  small 
intestine  enters  into  the 
mesentery,  or,  rather,  op- 
posite the  superior  mesen- 
teric artery  (m)  and  vein, 
which  pass  in  front  of  it. 
Its  fixed  position,  its  struc- 
ture, and  its  curvatures, 
have  led  to  its  being  de- 
scribed separately.* 

It  is  difficult  to  determine  its  precise  situation  with  regard  to  the  abdominal  parietes. 
It  is  not  exclusively  confined  to  any  one  region,  but  occupies  in  succession  the  adjacent 
borders  of  the  right  hypochondrium  and  the  epigastrium,  of  the  right  lumbar  and  the  um- 
bilical regions,  and  of  the  epigastric  and  umbilical  regions. 

The  duodenum  is  found  more  deeply  situated  in  proportion  as  we  recede  from  the  py- 
lorus, and  hence  the  difficulty  of  exploring  it  through  the  parietes  of  the  abdomen.  It 
is  fixed  firmly  in  its  place  by  the  peritoneum,  by  the  mesenteric  vessels  and  nerves, 
which  bind  it  down,  and  by  the  pancreas.  This  fixedness  is  one  of  its  principal  peculi- 
arities, and  is  indispensable  in  consequence  of  its  relations  with  the  ductus  communis 
choledochus  ;  for  had  it  been  movable  like  the  rest  of  the  small  intestine,  incessant  ob- 
structions to  the  flow  of  the  bile  would  have  occurred.  It  follows,  also,  that  the  duode- 
num can  never  form  part  of  a  hernia  ;  its  first  portion  may,  indeed,  be  displaced,  for  it 
is  less  firmly  fixed  than  the  remainder,  and  is  sometimes  dragged  out  of  its  proper  situ- 
ation by  the  pyloric  extremity  of  the  stomach. 

Dimensions. — It  is  eight  or  nine  inches  in  length  ;  its  calibre  is  somewhat  greater  than 
that  of  the  rest  of  the  small  intestine,  but  the  difference  is  not  so  decided  as  to  war- 
rant the  names  of  second  stomach,  or  ventriculus  sUccenturiatus,  which  have  been  given  to 
it.  I  have  even  met  with  subjects  in  whom  the  duodenum,  when  moderately  distended, 
was  five  inches,  while  the  succeeding  portion  of  small  intestine  was  six  inches  in  cir- 
cumference. It  has  been  supposed  that  this  part  is  more  dilatable  than  the  rest  of  the 
small  intestine  ;  this  has  been  attributed  to  the  absence  of  the  peritoneum.  The  fact 
and  the  explanation  are  equally  without  foundation.  It  is  the  fibrous  membrane,  and 
not  the  peritoneal  coat,  which  is  opposed  to  dilatation  of  the  intestines. 

Direction. — This  is  very  remarkable.  Commencing  at  the  pylorus,  the  duodenum 
passes  upward  to  the  right  side  and  backward  ;  having  reached  the  neck  of  the  gall- 
bladder, it  suddenly  changes  its  direction,  and  becomes  vertical,  forming  an  acute  angle 
■with  the  former  portion  ;  this  is  its  first  curvature  (e) :  then,  after  proceeding  vertically 
through  a  variable  space,  it  passes  transversely  from  the  right  to  the  left  side,  and  be- 
comes continuous  with  the  rest  of  the  small  intestine.  This  change  in  its  direction 
takes  place  at  a  right  angle,  and  is,  therefore,  less  abrupt  than  the  former  ;  the  point  at 
which  it  occurs  is  called  the  second  curvatare  (e'). 
*  Glisson  considered  the  insertion  of  the  ductus  communis  chnlfidochm!  "■••'"'  ".-er  limit  of  the  duodtJiiuni. 


THE    INTESTINES. 


363 


It  follows,  then,  that  the  duodenum  describes  a  double  curve,  or,  rather,  one  single 
curve,  of  which  the  concavity  is  directed  towards  the  left,  and  the  convexity  to  the  right 
side.  Haller  has  ingeniously-  compared  the  course  of  the  duodenum  to  two  parallel 
lines,  intersected  by  a  perpendicular.  This  double  change  in  the  direction  of  the  duode- 
num, which  is  probably  intended  to  retard  the  passage  of  the  food,  enables  us  to  consider 
it  as  composed  of  three  portions,  distinguished  as  the  first  (p  e),  second  (e  e'),  and  third  (e'  d). 

Relations. — These  should  be  studied  in  each  of  the  three  portions. 

Relations  of  the  First  Portion. — Above,  with  the  liver  (/',  fig.  154*)  and  the  gall-bladder 
(g),  to  the  neck  of  which  it  is  united  by  a  fold  of  the  peritoneum.  It  is  not  uncommon 
to  see  the  gall-bladder  and  the  duodenum  closely  adherent  to  each  other,  and  to  find  an 
opening  through  which  biliary  calculi  have  passed  into  the  gut.  Li  front,  with  the  gas- 
tro-colic  omentum  and  the  abdominal  parietes.  Behind,  with  the  hepatic  vessels,  and 
the  gastro-hepatic  omentum.  This  portion  of  the  duodenum,  which  may  be  denomi- 
nated the  hepatic,  is  about  two  inches  in  length. 

Relations  of  the  Second  Portion. — In  front,  with  the  right  extremity  of  the  arch  of  the 
colon  (t,fig.  161,  e  being  the  duodenum),  which  crosses  it  at  a  right  angle.  Behind,  with 
the  concave  border  of  the  right  kidney,  along  which  it  descends  to  a  greater  or  less  dis- 
tance, together  with  the  vena  cava  inferior  and  the  ductus  communis  choledochus.  Some- 
times this  portion  is  not  in  relation  with  the  kidney,  but  rather  with  the  vertebral  col- 
umn. The  ductus  communis  choledochus  {c,fig.  169)  and  the  pancreatic  duct  (m)  enter 
the  intestine  at  the  posterior  and  inner  surface,  and  below  the  middle  of  this  portion  of 
the  duodenum.  The  relations  of  the  duodenum  behind  are  direct,  i.  c.,  without  the  in- 
tervention of  the  peritoneum.  On  the  right,  this  portion  of  the  duodenum  is  in  relation 
with  the  ascending  colon  {a,  fig.  161).  On  the  left,  with  the  pancreas  {o,fig.  154),  which 
is  closely  united  to  it,  and  embraces  it  in  a  sort  of  half  groove.  This  second  portion  is 
two  or  three  inches  in  length  ;  it  may  be  called  the  renal  portion. 

Relations  of  the  Third  Portion. — The  third  portion  is  situated  in  the  substance  of  the 
adherent  border  of  the  transverse  mesocolon.  Below,  it  rests  upon  the  lower  border  of 
that  fold.  Above,  it  is  bounded  by  the  pancreas,  which  adheres  closely  to  it.  In  front, 
it  corresponds  to  the  stomach,  from  which  it  is  separated  by  the  layer  of  peritoneum 
which  lines  the  sac  of  the  great  omentum.  Behind,  it  corresponds  to  the  vertebral  col- 
lunn,  from  which  it  is  separated  by  the  aorta  (a),  the  vena  cava,  and  the  pillars  of  the 
diaphragm  {d  d).i 

As  the  internal  surface  and  the  structure  of  the  duodenum  are  very  analogous  to  those 
of  the  jejunum  and  ileum,  I  shall  postpone  the  description  until  I  have  noticed  the  exter- 
nal conformation  of  the  rest  of  the  small  intestine. 

Fig.  155. 
The  Small  Intestine,  or  the  Jejunnm  and 

Ileum. 
The  small  intestine,  properly  so  call- 
ed (c  d,fig.  139  ;  i  i  i,fig.  155),  or  the 
jejunum  and  ileum,  consists  of  that  por- 
tion of  the  alimentary  canal  which  fills 
almost  the  whole  of  the  abdomen,  oc- 
cupies the  mnbilical,  hypogastric,  iliac, 
and  lumbar  regions,  and  is  surround- 
ed, as  it  were,  more  or  less  complete- 
ly, by  the  large  intestine  {efgh,  fig. 
139 ;  a  t  d,  fig.  155).  Its  upper  ex- 
tremity (/  fig.  161)  is  continuous, 
without  any  hne  of  separation,  with 
the  duodenum.  The  distinction  be- 
tween the  two  parts  is  established  by 
the  angle  which  the  mesentery  forms 
with  the  mesocolon,  or,  rather,  by  the 
point  where  the  superior  mesenteric 
vessels  cross  over  the  small  intestine. 
Its  lower  extremity  {d,fig.  139  ;  i,fig. 
161)  enters  at  a  right  angle  into  the 
large  intestine.  The  old  division  of 
the  small  intestine  into  the  jejunum 
and  ileum  should  be  banished  with  oth- 
er anatomical  niceties,  for  it  is  found- 
ed only  upon  trivial  distinctions  ;  and 
although  the  upper  part  of  this  intes- 
tine differs  in  many  respects  from  the 

*  In  which  figure  the  liver  and  stomach  are  turned  upward. 

t  In  one  subject  I  found  a  fourth  portion  which  passed  upward,  and  was  ahmit  one  inch  ir  len!?th,  so  that 
the  duodenum  described  a  third  curve,  with  its  conc.avitv  directed  to  the  right. 


364  SPLANCHNOLOGY. 

lower,  still  the  alteration  takes  place  by  imperceptible  gradations.*  So  that  Winslow, 
unable  to  find  any  real  difference,  established  a  purely  conventional  distinction,  by  pro- 
posing to  call  the  upper  two  fifths  the  jejunum,  and  the  lower  three  fifths  the  ileum. 

No  portion  of  the  alimentary  canal  is  so  movable  as  the  small  intestine,  properly  so 
called.  It  is  exceedingly  loosely  attached,  or,  as  it  were,  suspended  from  the  vertebral 
column,  by  a  large  fold  of  the  peritoneum,  called  the  mesentery  (the  attached  portion  of 
which  is  seen  at  m,fig.  161),  which,  being  broader  in  the  middle  than  at  either  extrem- 
ity, gives  an  unequal  mobility  to  the  different  parts  supported  by  it.  The  small  intes- 
tine is  displaced  with  great  facility. 

The  circular  boundary  described  around  it  by  the  large  intestine  is  only  exact  above, 
where  the  mesocolon  and  the  arch  of  the  colon  («,  fig.  155)  completely  separate  it  from  the 
stomach  («),  the  liver  (Z),  the  spleen  (k),  and  the  duodenum.  But  below,  between  the 
caecum  {c,fig-  161)  and  the  sigmoid  flexure  of  the  colon  (/),  it  descends  into  the  pelvis, 
and,  extending  laterally,  passes  in  front  of  the  colon  in  both  the  right  and  left  lumbar  re- 
gions. 

This  excessive  mobility  is  one  of  the  most  characteristic  and  important  facts  regarding 
the  small  intestine,  which,  in  some  measure,  floats  in  the  abdominal  cavity,  yielding  to 
the  slightest  impulse  or  concussion.  Of  all  the  viscera,  it  is  the  most  frequently  involv- 
ed in  hernia.  It  is  liable  to  invagination,  i.  e.,  one  portion  may  be  received,  as  into  a 
sheath,  into  that  immediately  succeeding  it.  When  any  organ  in  the  abdomen  becomes 
enlarged,  the  small  intestine  yields,  and  passes  in  the  direction  where  there  is  least  re- 
sistance. It  appears  to  partake  of  the  mobility  of  fluids.  It  collects  together,  or  spreads 
out ;  it  moulds  itself  upon  the  adjacent  parts,  and  fills  up  every  space,  so  as  to  elude  aU 
causes  of  compression  ;  and,  by  means  of  this  admirable  contrivance,  the  abdomen  ac- 
commodates itself  without  inconvenience  to  the  occasional  enormous  development,  either 
natural  or  diseased,  of  the  organs  contained  within  it. 

Direction. — We  have  seen  that  the  upper  or  supra-diaphragmatic  portion  of  the  diges- 
tive canal  is  straight.  The  stomach  presents  one  slight  curve.  The  duodenum  has  two 
decided  curves,  and  the  rest  of  the  small  intestine  pursues  a  not  less  flexuous  course. 
The  following  is  the  direction  of  this  intestine:  commencing  at  the  duodenum  {j,fig- 
161),  it  passes  forward  and  to  the  left  side  ;  it  is  then  folded  a  great  number  of  times 
upon  itself,  and,  at  its  lower  part,  it  passes  transversely  from  the  left  to  the  right  side, 
and  a  little  upward,  in  order  to  enter  at  a  right  angle  (i)  into  the  great  intestine. 

The  numerous  foldings  or  turnings  (gyri)  of  the  small  intestine  upon  itself  have  re- 
ceived the  name  of  convolutions ;  they  are  moulded  upon  each  other,  without  intermixing 
or  becoming  entangled,  so  as  to  form  a  mass,  which  so  closely  resembles  the  surface  of 
the  brain,  that  the  term  convolutions  has  also  been  applied  to  the  winding  eminences  of 
that  organ. 

Each  convolution  represents  an  almost  complete  circle.  In  the  complexity  presented 
by  the  numerous  windings  of  the  small  intestine,  it  appears  to  be  very  difficult  to  assign 
to  it  any  general  direction ;  nevertheless,  if  we  consider  that  the  small  intestine  com- 
mences to  the  left  of  the  second  lumbar  vertebra,  and  terminates  in  the  right  iliac  fossa, 
it  will  be  seen  that  its  general  direction  coincides  with  that  of  the  membranous  fold  (m, 
Jig.  161)  which  supports  it ;  that  is,  it  may  be  expressed  by  an  oblique  line  ruiming 
downward  from  the  left  to  the  right  side.  If,  however,  we  examine  the  particular  di- 
rection of  the  convolutions,  we  shall  find  that  they  all  present  a  concavity  towards  the 
mesentery,  and  a  convexity  towards  the  parietes  of  the  abdomen,  so  that  each  resem- 
bles the  half  of  the  figure  8.  In  consequence  of  this  arrangement,  the  intestine  may  be- 
come folded  without  much  change  in  its  position,  either  in  advance  or  otherwise  ;  and 
hence  the  great  number  of  folds  which  can  be  placed  between  two  points  so  near  each 
other  as  the  left  side  of  the  second  lumbar  vertebra  and  the  right  iliac  fossa,  the  distance 
between  which  is  not  more  than  four  inches. 

Dimensions. — The  determination  of  the  length  of  the  small  intestine,  properly  so  called, 
has  at  all  times  been  a  subject  of  interest.  Meckel  says  that  it  varies  from  thirteen  to 
twenty-seven  feet,  including  the  duodenum.  According  to  my  observations,  it  varies 
from  ten  to  twenty-five  feet  in  the  adult,  t  The  length  of  the  small  intestine,  compared 
to  that  of  the  large  intestine,  is  generally  as  five  to  one.  The  different  results  which 
have  been  obtained  by  various  authors  may  be  explained  partly  by  individual  varieties 
and  partly  by  the  mode  in  which  the  measurements  were  made.  Thus,  a  more  or  less 
perfect  separation  of  the  gut  from  the  membranous  folds  which  support  it  would  lead  to 
different  results.  But  another,  and  less  understood  cause  of  difference,  is  the  influence 
of  the  caliber  of  the  intestine  upon  its  length.  The  caliber  and  the  length  have  always 
an  inverse  ratio  to  each  other.  Of  this  we  may  be  easily  convinced,  by  strongly  infla- 
ting a  portion  of  gut  which  has  been  previously  measured.     I  have  often  been  struck 

*  The  upper  part  of  the  intestine  is  caWed  jejunum,  because  it  is  generally  found  empty  ;  the  second,  ileum, 
either  because  it  has  been  supposed  chiefly  to  occupy  the  iliac  regions,  or  on  account  of  its  convoluted  disposi- 
tion, which,  however,  is  common  to  it  with  the  other  (tiXtti',  to  turn,  to  twist). 

t  The  average  length  of  the  small  intestine,  including  the  duodenum,  is  20  feet.  I  have  lately  measured 
several :  in  a  female  affected  with  chronic  peritonitis,  it  was  only  7  feet  long ;  in  another,  14  ;  in  a  third,  18 ; 
in  a  fourth,  20  ;  and  in  a  fifth,  22. 


THE    INTESTINES.  365 

with  the  shortness  of  the  small  intestine  in  cases  of  hernia,  accompanied  with  retention 
of  the  contents  of  the  gut  above  the  strangulation. 

Some  authors  have  attempted  to  establish  a  relation  between  the  length  of  the  intes- 
tine and  the  stature  of  the  individual ;  and  it  has  been  affirmed  that  the  former  is  four 
or  five  times  the  height  of  the  body.  But  differences  in  stature  have  not  a  uniform  rela- 
tion to  the  length  of  the  alimentary  canal. 

Lastly,  individual  varieties  in  the  length  of  the  small  intestine  do  not  appear  to  h8T6 
any  influence  upon  the  activity  of  the  digestive  process. 

Caliber. — The  cahber  of  the  small  intestine,  properly  so  called,  is  not  the  same  through- 
out. It  is  greater  at  the  commencement  than  at  the  termination  of  the  intestine.  When 
moderately  distended  by  inflation,  I  have  found  it  six  inches  and  four  hnes  in  circum- 
ference at  its  commencement,  four  inches  and  two  lines  at  the  middle,  and  three  inches 
and  a  half  a  little  above  its  entrance  into  the  large  intestine  ;  but  at  the  point  of  entrance 
itself  it  is  dilated  to  about  four  inches  and  a  half 

The  small  intestine,  therefore,  is  funnel-shaped,  a  form  which  must  facilitate  the  rapid 
passage  of  its  contents,  by  causing  them  to  proceed  from  a  wider  into  a  narrower  space. 

Lastly,  the  caliber  of  the  small  intestine  presents  many  varieties.  When  any  obstruc- 
tion occurs  to  the  passage  of  its  contents,  it  may  attain  the  caliber  of  the  large  intestine. 
In  certain  cases  of  marasmus,  when  it  contains  no  gases,  it  becomes  so  contracted  that 
the  tube  is  completely  obliterated. 

Figure  and  Relations. — The  smaU  intestine  is  cylindrical ;  a  section  of  it  is  almost  cir- 
cular. Its  posterior  harder,  to  which  the  mesentery  is  attached,  is  concave  ;  it  is  thrown 
into  shght  folds,  as  every  straight  cylinder  must  be  when  it  is  bent  into  a  curve.  Its 
anterior  border  is  convex,  free,  and  corresponds  to  the  abdominal  parietes,  being  separa- 
ted from  them  by  the  great  omentum,*  which  seems  intended  to  contain  the  whole  mass 
of  the  intestinal  convolutions.  When  the  omentum  is  wanting,  as  in  the  foetus,  or  in 
cases  of  displacement  from  its  being  rolled  up  into  a  cord,  the  small  intestine  is  in  im- 
mediate contact  with  the  parietes  of  the  abdomen. 

The  lateral  surfaces  of  the  different  convolutions  of  the  small  intestine  are  in  contact 
with  each  other.  As  these  surfaces  are  convex,  they  intercept  triangular  spaces  before 
and  after  them,  in  which  either  effused  blood,  or  serum,  or  pus,  or  false  membranes,  are 
sometimes  collected. 

The  small  intestine  corresponds  to  all  the  regions  of  the  abdomen,  excepting  those  of 
the  upper  zone.  Not  uncommonly,  we  find  it  escaped  from  under  the  omentum,  and  sit- 
uated between  the  hver  and  the  abdominal  parietes,  or  reaching  into  the  left  hypochon- 
drium.  It  is  immediately  forced,  as  it  were,  in  any  direction  in  which  there  may  be  an 
opening,  t 

More  or  less  of  the  small  intestine  is  always  found  in  the  pelvis ;  in  the  male,  between 
the  bladder  and  the  rectum ;  in  the  female,  between  the  bladder  and  the  uterus,  and  be- 
tween the  uterus  and  the  rectum.  In  several  persons  who  were  emaciated  from  chronic 
diseases,  and  in  whom  the  vertebral  column  could  be  plainly  felt  through  the  parietes  of 
the  abdomen,  I  have  found  almost  the  whole,  and,  in  some  cases,  even  the  whole,  of  the 
small  intestine  within  the  pelvis,  contracted,  and  almost  entirely  void  of  air.  When  one 
portion  only  of  the  small  intestine  is  in  the  pelvis,  it  is  invariably  the  lower  part. 

WTien  any  large  mass  is  developed  in  the  abdomen,  as  in  pregnancy,  or  in  encysted 
dropsy  of  the  ovarium,  the  small  intestine  passes  upward  and  laterally,  becomes  diffu- 
sed, fills  up  every  space,  and  almost  always  escapes  compression  in  the  most  remarka- 
ble manner. 

It  is  not  uncommon  to  find,  in  the  small  intestine,  appendices  or  diverticula,  like  the 
fingers  of  a  glove,  which  are  sometimes  two  or  three  inches  in  length,  and  have  been 
found  in  the  sacs  of  herniae.  These  diverticula  are  usually  much  nearer  the  lower  than 
the  upper  part  of  the  small  intestine.  They  are  formed  by  all  the  coats  of  the  bowel, 
and  are  very  different  from  mere  protrusion  of  the  mucous  membrane  through  the  mus- 
cular coat,  of  which  I  have  seen  one  example  in  the  duodenum,  and  which  I  have  often 
met  with  in  other  parts  of  the  small  intestine.  In  a  subject  which  I  recently  examined, 
the  small  intestine  presented  about  fifty  spheroidal  tumours  of  unequal  size,  all  situated 
along  the  mesenteric  side  of  the  gut,  and  formed  by  protrusions  of  the  mucous  membrane 
through  the  muscular  fibres. 

Structure  of  the  Small  Iritesttne. 
Dissection. — This  structure  must  be  studied  upon  a  distended  and  moist  portion  of  in- 
testine, upon  a  distended  and  dried  specimen,  and  also  upon  one  inverted  and  distended. 
It  is  also  of  importance  to  study  the  mucous  membrane  under  water,  with  the  assistance 
of  a  strong  lens.  Injections  thrown  in  first  by  the  veins,  and  then  by  the  arteries,  are 
also  useful  in  developing  its  structure. t 

*  [Injig.  155,  the  great  omentum  has  been  removed.]  .    . 

t  The  small  intestine  is  found  in  diaphragmatic  hernicc  ;  it  constitutes  perineal  hernia  ;  and  it  is  this  por 
ion  of  the  bowels  which  escapes  from  the  pelvis  when  the  lower  wall  of  that  cavity  is  divided. 
t  The  internal  surface  of  the  small  intestine  will  be  noticed  with  the  mucous  membrane. 


1 


i 


366  SPLANCHNOLOGY. 

The  small  intestine,  as  well  as  the  stomach,  is  formed  of  four  coats  or  membranes, 
which,  proceeding  from  without  inward,  are  the  serous,  muscular,  fibrous,  and  mucous  coats. 

The  Serous  Coat. — The  arrangement  of  this  coat  upon  the  duodenum  differs  from  that 
upon  the  rest  of  the  small  intestine. 

The  peritoneum  is  apphed  to  the  first  portion  of  the  duodenum  in  the  same  way  as 
upon  the  stomach,  i.  e.,  it  covers  it  entirely,  excepting  in  front  and  behind,  where  there 
is  a  triangular  space  devoid  of  this  coat.  Like  the  stomach,  this  first  portion  gives  at- 
tachment to  the  great  omentum  in  front,  and  to  the  small  omentum  behind.  The  fold 
of  peritoneum  which  passes  from  the  liver  to  the  duodenum  has  been  improperly  called 
the  hepatic  ligament  of  the  duodenum.  The  peritoneum  merely  passes  over  the  front  of 
the  second  and  third  portions  of  the  duodenum,  so  that  the  posterior  surface  of  the  in- 
testine is  in  immediate  contact  with  the  parts  with  which  it  is  in  relation,  and  is  very 
perfectly  fixed. 

The  peritoneum  forms  a  complete  sheath  for  the  small  intestine,  properly  so  called,  ex- 
cepting along  its  concave  border,  where  the  two  layers  which  constitute  the  mesentery 
separate  from  each  other,  so  as  to  include  the  bowel.  In  this  situation  we  find  a  trian- 
gular cellular  space,  exactly  resembling  those  which  we  have  already  described  along  the 
curvatures  of  the  stomach,  and  performing  a  similar  office,  viz.,  that  of  remedying  the 
slight  extensibility  of  the  peritoneum,  and  permitting  the  intestine  to  undergo  sudden 
dilatation  to  a  great  extent.  We  should  have  a  very  incorrect  notion  of  the  dilatability 
of  the  intestine  if  we  imagined  that  it  is  limited  by  the  triangular  space  along  its  con 
cavity,  for  when  the  bowel  is  much  distended,  the  mesentery  itself  becomes  separatee 
into  its  two  layers  to  allow  of  such  distension.  Of  this  I  am  convinced  from  having 
measured  the  antero-posterior  diameter  of  the  mesentery  both  before  and  after  inflation 
of  the  bowels. 

The  cellular  tissue  which  unites  the  peritoneal  to  the  muscular  coat  is  extremely  del- 
icate, and  its  adhesion  to  the  latter  coat  increases  in  proceeding  from  the  concave  to  the 
convex  border  of  the  intestine.  Although  the  peritoneal  coat  is  very  thin,  and  so  trans- 
parent that  the  muscular  fibres  may  be  seen  through  it,  yet  it  has  considerable  strength. 

The  muscular  coat  is  composed  of  two  layers  of  involuntary  muscular  fibres,  one  su- 
perficial, the  other  deep.  The  superficial  layer  is  the  thinner  ;  it  consists  of  longitudinal 
fibres  placed  around  the  bowel  in  a  very  regular  manner,  and  forming  a  continuous  plane. 
I  have  never  found  these  fibres  more  numerous  at  the  mesenteric  than  at  the  convex 
border.  This  layer  of  fibres  is  almost  always  removed  with  the  peritoneal  coat,  to  which 
it  adheres  very  intimately.  From  their  white  colour  and  shining  appearance  under  the 
serous  membrane,  they  have  been  supposed  to  be  of  a  tendinous  nature. 

It  is  difficult,  though  by  no  means  important,  to  determine  exactly  whether  the  same 
fibres  reach  the  whole  length  of  the  intestine,  or  whether  they  are  interrupted  at  inter- 
vals. It  is  generally  admitted  that  they  are  interrupted,  and  that  their  extremities  are 
received  in  the  spaces  between  other  fibres. 

The  deep  layer  of  muscular  fibres  is  thicker  than  the  preceding,  and  consists  of  circu- 
lar fibres,  either  parallel  or  crossing  each  other  at  very  acute  angles.  They  appear  to 
me  to  describe  complete  circles,  and  to  have  their  ends  united.  They  have  no  tendinous 
intersections. 

The  fibrous  coat  is  intermediate  between  the  muscular  and  mucous  tunics,  and  presents 
the  same  characters  as  in  the  stomach. 

The  Mucous  or  Papillary  Membrane. — Its  external  surface  adheres  to  the  fibrous  membrane 
by  a  loose  cellular  tissue,  which  is  liable  to  serous,  sanguineous,  and  purulent  infiltra- 
tion. The  emphysematous  or  cedematous  condition  may  be  imitated  in  the  dead  body, 
by  everting  a  portion  of  bowel  and  distending  it  either  with  air  or  water.  The  tenuity 
of  the  mucous  membrane  displayed  in  these  experiments  has  led  to  the  opinion  that  this 
coat  is  nothing  more  than  an  epithelium,  a  continuation  of  the  epidermis  of  the  skin,  and 
that  the  fibrous  coat  represents  the  cutaneous  dermis.  Its  internal  surface  is  free,  and 
is  covered  with  more  or  less  mucus ;  it  is  remarkable  for  its  duphcatures  or  valves,  call- 
ed valvules  conniventes ;  for  its  highly-developed  papillee,  and  for  the  arrangement  of  its 
follicles. 

The  ValvulcB  Conniventes  {Valvulce  Intestinales). 

Dissection. — Evert  the  small  intestine,  so  that  its  external  surface  becomes  internal,  and 
then  plunge  it  in  water ;  or,  what  is  better,  lay  open  the  bowel,  and  examine  its  internal 
surface  under  water.    Also  study  a  portion  of  intestine  inflated  and  dried. 

Hitherto  the  mucous  membrane  of  the  alimentary  canal  has  only  presented  to  our  no 
tice  certain  folds  which  are  intended  to  facilitate  the  dilatation  of  that  canal,  as  in  the 
cesophagus  and  stomach,  and  which  are  completely  effaced  by  distension.  The  folds  of 
the  mucous  membrane  of  the  small  intestine  fulfil  another  purpose  ;  and  although  they 
must,  undoubtedly,  in  some  measure  assist  in  the  elongation  and  dilatation  of  the  bowel, 
yet  they  are  never  entirely  effaced,  however  far  this  extension  in  length  or  width  maj 
be  carried.  These  folds  deserve  a  special  description.  They  are  called  valvulce  conni- 
ventes or  the  valves  of  Kerkringius,  although  Fallopius  had  given  a  complete  description 


THE   INTESTINES.  367 

of  them  before  that  anatomist.  Kerkringius  gave  them  the  name  of  conniventes  {con 
niveo,  to  close  partially).  They  commence  in  the  duodenmn  (see  fig.  169),  an  inch,  oi 
sometimes  two  inches,  from  the  pylorus  ;  and  it  is  not  unconunon  to  find  them  preceded 
by  some  vertical  folds.  They  are  few  and  small  at  first,  but  become  very  numerous  and 
very  large  towards  the  end  of  the  duodenum  and  the  commencement  of  the  small  intestine, 
properly  so  called.  From  the  upper  two  fifths  of  that  intestine  they  gradually  diminish 
in  number,  and  become  less  regular  and  less  marked  towards  the  lower  part  of  the  small 
intestine ;  sometimes  they  are  altogether  wanting  in  the  last  two  or  three  feet  of  the 
bowel.  In  some  rare  cases,  I  have  seen  valvulae  conniventes  as  far  down  as  the  ileo- 
caecal  valve  ;  in  no  part  are  they  sufficiently  numerous  to  have  a  true  imbricated  arrange- 
ment. These  valves  are  placed  perpendicularly  to  the  axis  of  the  intestine,  and  describe 
one  half,  two  thirds,  or  three  fourths  of  a  circle  ;  but  they  seldom  form  a  complete  ring. 
They  are  broader  in  the  middle,  being  from  two  or  three  lines  in  width,  than  at  their  ex- 
tremities, which  are  slender.  In  order  to  ascertain  their  dimensions,  they  must  be 
placed  under  water,  or  studied  upon  a  fresh  portion  of  intestine.  They  are  generally 
parallel,  incline  towards  each  other  by  their  extremities,  bifurcate,  and  send  off  smdj 
verticular  oblique  prolongations.  Sometimes  we  find  small  valves  placed  between  the 
larger  ones.  Some  of  them  are  suddenly  interrupted,  so  that  they  might  be  supposed,  at 
first  sight,  to  have  undergone  some  loss  of  substance.  Several  of  them  are  alternate, 
and  seem  to  be  disposed  in  a  spiral  manner ;  but  there  is  no  general  rule  in  this  respect ; 
their  free  edge  is  sometimes  directed  towards  the  pylorus,  and  sometimes  towards  the 
ileo-cffical  valve.  Their  direction  is  very  irregular ;  they  yield  to  any  impulse  that  may 
be  conamunicated  to  them,  and  their  free  edge  passes  either  upward  or  downward,  ac- 
cording to  circumstances.  When  examined  upon  a  dried  specimen,  they  resemble  very 
much  the  diaphragms  in  optical  instruments. 

The  valvulae  conniventes  are  formed  by  folds  of  mucous  membrane,  within  which  we 
find  some  loose  cellular  tissue,  different  kinds  of  vessels  and  nerves.  Inflation,  by  rais- 
ing the  mucous  membrane,  completely  effaces  them.  The  fibrous  coat  presents  a  slight 
thickening  opposite  the  bases  of  these  valves.  The  valves,  notwithstanding  the  ease 
with  which  they  are  moved,  must  in  some  manner  retard  the  passage  of  the  food,  with- 
out offering  any  decided  resistance  to  it,  for  that  would  become  a  cause  of  obstruction, 
and  give  rise  to  serious  accidents.  Their  chief  use,  perhaps,  is  to  increase  the  extent 
of  surface  ;  according  to  Fabricius,  they  double  the  surface  of  the  intestine  ;  Fallopius 
says  they  increase  it  three  times,  and  Kew  six  times.  Soemmering  has  given  the  some- 
what conjectural  opinion,  that  the  surface  of  the  intestinal  mucous  membrane  is  greater 
than  that  of  the  entire  skin  (Corpor.  Hum.  Fabrica,  t.  vi.,  p.  295).  Although  not  peculiar 
to  the  human  species,  they  are  much  more  developed  in  man  than  in  the  lower  animals. 

Besides  the  valvulag  conniventes,  the  mucous  membrane  of  the  small  intestine  presents 
some  irregular  folds,  which  are  effaced  by  distension. 

The  PapilloR,  or  Villi. 

Preparation. — 1.  Place  the  opened  intestine  in  water,  exposing  it  to  a  strong  light,  and 
agitate  the  fluid.  A  stream  of  water  previously  received  upon  the  membrane  will  re- 
move the  mucus,  which  sometimes  forms  a  tenacious  sheath  around  each  papilla.*  2. 
Roll  up  a  portion  of  the  detached  mucous  membrane,  taking  care  to  turn  the  adherent 
surface  inward.  3.  Evert  a  loop  of  intestine,  so  that  the  peritoneal  coat  may  be  on  the 
inside :  stretch  it  upon  a  cylinder,  and  then  agitate  it  in  a  cylindrical  vessel,  so  as  to 
float  out  the  valves. 

The  papilla,  or  villi,  are  much  more  developed  in  the  small  intestine  than  in  any  other 
part  of  the  alimentary  canal,  with  the  exception  of  the  tongue.  Fallopius  has  the  honour 
of  having  discovered  them.  They  were  T,vell  described  by  Helvetius,  Hewson,  and  Lie- 
berkuhn,  but  still  more  accurately  of  late  by  Albert  Meckel.  When  examined  by  the 
naked  eye  and  under  the  microscope,  the  internal  surface  of  the  intestine  appears  to  be 
roughened  by  an  inunense  number  of  prominences  or  vilh  {figs.  157,  159),  resembling 
very  close,  short  grass,  or  a  very  hairy  caterpillar.  In  some  animals,  as  in  the  dog,  and 
especially  in  the  bear,  the  villi  are  so  numerous  and  so  long,  that  they  in  some  degree 
resemble  the  filzmientous  roots  of  plants.  They  are  found  through  the  whole  length  of 
the  small  intestine,  and  cover  the  valvulae  conniventes,  as  well  as  the  intervals  between 
them.  They  vary  in  length :  according  to  Lieberkuhn,  they  are  one  fifth  of  a  line  ;  their 
maximum  length  appears  to  be  about  four  fifths  of  a  line  :  and  I  have  even  found  some 
in  the  duodenum,  which,  when  extended,  were  a  line  in  length ;  their  number  is  very  con- 
siderable, and  attempts  havQ  been  made  to  determine  it.  Lieberkuhn  computed  them  at 
500,000.  Several  Germans  have  taken  up  the  subject ;  allowing  4000  to  every  square 
inch,  by  a  calculation,  the  exactness  of  which  I  have  not  verified,  there  would  be  a  mill- 
ion altogether.  I  have  not  observed  any  well-marked  difference  as  regards  the  number 
of  the  vilh,  between  the  commencement  and  the  termination  of  the  small  intestine.    It 

*  A.  Meckel  recommends  that  the  mucus  should  be  removed  by  plunging  the  intestine  first  in  an  arsenical 
solution,  and  then  in  water  impregnated  with  sulphuretted  hydrogen  ;  but  the  continued  action  of  a  stream  of 
water  is  far  preferable. 


368 


SPLANCHNOLOGY. 


appears  to  me  that  the  number  and  length  of  the  villi  are  much  greater  in  carnivora  than 
in  herbivora.  The  otter  has  been  said  to  have  the  largest  vilU  of  any  animal.  Their 
form  varies  much.  In  the  majority  of  animals  which  I  have  examined,  as  the  dog,  cat, 
calf,  and  bear,  they  are  fUiform.  In  the  human  subject  they  are  all  lamellar  or  foliaceous, 
but  with  many  varieties.  In  the  duodenum  they  are  curved  upon  themselves,  presenting 
the  appearance  of  a  calyx  or  corolla,  and  sometimes  adhering  to  each  other  by  their  ex- 
tremities. In  the  small  intestine,  properly  so  called  {figs.  157,  159),  they  are  rectilinear, 
floating,  cylindrical,  conical,  clubbed  at  the  end,  constricted,  and  sometimes  bent  in  the 
middle.  In  the  neighbourhood  of  ulcerations,  they  are,  as  it  were,  cut  oiF  close  or  trun- 
cated, without  presenting  any  alteration  in  their  structure. 

Structure. — Brunner  calls  them  membranous  tubes  ;  Leeuwenhoek  regarded  them  as 
muscular  organs  ;  Helvetius  and  Hewson  considered  them  to  be  small  valves,  an  idea 
which  has  been  revived  and  carried  out  more  lately  by  Albert  Meckel.  This  anatomist, 
who  has  given  representations  of  the  villi  in  a  great  number  of  animals  {Journ.  Comple- 
ment, t.  vii.,  p.  209),  regards  them  as  formed  of  small  Icunellae,  sometimes  twisted  upon 
their  axes,  like  the  first  leaf  of  a  germinating  grain  of  wheat,  and  sometimes  folded  into 
a  semi-canal  or  groove ;  but  he  considers  that  all  these  varieties  m^y  be  referred  to  that 
of  a  lamella,  broad  at  the  base  and  narrow  at  the  apex ;  a  fundamental  form,  which  may 
always  be  demonstrated  with  the  aid  of  a  needle.* 

Lieberkuhn  states,  that  at  the  base  of  each  villus  there  is  an  ampulla,  which  opens 
upon  the  summit  of  the  villus  by  a  single  orifice ;  and  he  considers  that  both  the  ampul- 
la and  the  orifice  belong  to  the  commencement  of  the  lacteal  vessels  ;  arteries  and  veins 
ramify  round  the  ampuUa  ;  and  each  villus  has  an  afferent  artery  and  an  efferent  vein. 
According  to  Mascagni,  the  villi  are  composed  of  an  interlacement  of  bloodvessels  and 
smEill  lymphatics,  and  are  covered  by  an  extremely  thin  membrane,  composed  of  lym- 
phatics. The  following  are  the  results  of  my  own  observations  :  Having  had  occasion 
to  examine  a  subject  in  which  the  lymphatic  vessels  were  filled  with  tubercular  matter, 
I  was  able  to  trace  a  lymphatic  trunk  into  each  villus  (vide  Anat.  Path,  avec  planches, 
liv.  2),  which  traversed  its  entire  length.  This  perfectly  agrees  with  Lieberkuhn's  ac- 
count. In  another  subject  I  injected  mercury  into  one  of  the  mesenteric  veins,  and  then 
above  the  mercury  I  forced  in  a  coarse  black  injection.  The  mercury  and  a  part  of  the 
black  injection  passed  into  the  cavity  of  the  intestine,  and  a  globule  of  mercury  appear- 
ed upon  the  summits  of  the  villi,  which  were  blackened  from  the  injection.  From  this 
I  have  concluded  that  the  villi  are  perforated  at  their  summits.  I  shall  return  to  this 
subject  again. t 

The  Duodenal  Glands  and  Follicles.  Preparation. — Some  intestines  are  not  well  adapt- 
ed for  the  study  of  the  follicles,  which,  indeed,  seem  to  be  entirely  wanting  in  them. 
Others,  again,  are  very  favourable  for  that  purpose.  The  folhcles  are  rendered  more 
apparent  by  plunging  the  intestine  into  acidulated  water.  They  must  be  examined  from 
the  internal  surface  of  the  mucous  membrane,  and  also  from  its  external  surface,  by  re- 
moving the  serous,  muscular,  and  fibrous  coats  by  which  they  are  covered.  In  the  study 
of  the  duodenal  glands,  this  last  method  of  investigation  is  absolutely  necessary. 

The  follicles  are  generally  divided  into  two  kinds,  the  simple  or  solitary,  and  the  ag- 
minated ;  to  these  we  shall  add  the  duodenal  glands. 

The  Duodenal  Glands. — These,  properly  speaking,  are  the  glands  of  Brunner.  This  anat- 
omist, who  had  already  made  some  curious  experiments  upon  the  pancreas,  says  that, 
having  partially  boiled  the  duodenum,  he  observed  upon  its  internal  membrane  some 
granular  bodies,  which  he  has  had  figured,  resembling  the  solitary  follicles  in  the  neigh- 
bouring portion  of  intestine.  To  this  collection  of  granules  he  gave  the  name  of  the  sec- 
ond pancreas.     Farther  observations  have  shown,  that  in  the  upper  half,  or  upper  two 

*  [Many  of  the  villi  are  certainly  cylindrical,  and,  therefore,  not  referrible  to  the  fundamental  form  described 
by  Albert  Meckel.  In  the  fostus  and  young  subject  they  are  comparatively  broader  and  flatter,  and  are  con- 
nected at  their  bases  so  as  to  form  folds  having  irregular  margins.  In  this  stage  of  their  development  they  re- 
semble the  rugiB  in  the  intestines  of  birds  and  reptiles.] 

t  [The  villi  contain  all  the  elements  of  the  intestinal  mucous  membrane  ;  no  nerves,  however,  have  been  ao- 
toally  demonstrated  in  them. 


Fig.  156. 


The  bloodvessels  are  numerous,  and  form  a  very 
Deautiful  capillary  network  in  each  \';llu8  (3,  Jig. 
156). 

Great  differences  of  opinion  have  existed,  and  still 
exist,  as  to  the  mode  of  origin  of  the  lacteals  in  the  in- 
testinal villi ;  the  best  authorities,  however,  agree  in 
stating  that  they  do  not  commence  by  open  orifices. 
Rudolphi  and  A.  Meckel  considered  that  they  arose  by 
a  closed  network.  Dr.  Ilenle  found  a  single  dilated 
but  closed  lacteal  in  each  viUosity ;  and  more  recent- 
ly, Krause  observed  that  in  each  villus  the  lacteal 
arose  by  several  branches,  some  of  which  ended  in 
free  but  closed  extremities,  while  others  anastomosed 
together  (i,fig.  156).  The  villi,  and,  it  may  be  ob- 
served here,  every  portion  of  the  intestinal  mucous 
membrane,  are  covered  by  a  transparent,  columnar  epithelium,  consisting  of  elongated  prismatic  nucleated  cor- 
puscules.  The  perpendicular  arrangement  of  these  upon  the  surface  of  a  villus  is  shown  in  the  diagram  (1, 
%.  156).] 


THE   INTESTINES. 


thirds  of  the  duodenum,  there  is  a  layer  of  flattened  granular  bodies,  perfectly  distinct 
from  each  other,  however  close  they  may  be.  This  layer  must  not  be  confounded  with 
the  glanduliform  arrangement  of  the  duodenal  villi ;  it  can  only  be  well  seen  after  hav- 
ing removed  the  three  outer  coats.  These  granular  bodies  are  nothing  more  than  small 
(compound)  glands,  which,  when  examined  with  a  powerful  lens,  present  all  the  charac 
ters  of  the  salivary  glands.  These  glands  do  not  cease  abruptly,  but  become  few  and 
scattered  towards  the  lower  end  of  the  duodenum  ;  so  that  it  is  by  no  means  inconsist- 
ent to  admit  that  the  solitary  folhcles  of  the  rest  of  the  intestinal  canal  may  be  of  a  simi- 
lar nature.* 

The  solitary  follicles,  or  glandula  solitaries,  are  generally  known  in  the  present  day  ao 
the  glands  of  Brunner  {Disput.  de  Gland  Duoden.,  Heidelberg,  1687,  1715),  although  that 
anatomist  only  described  the  glands  or  follicles  of  the  duodenum,  which  he  said  dimin- 
ished in  number  below  that  portion  of  the  intestine,  and  disappeared  adtogether  in  the  je- 
junum. It  is,  therefore,  by  an  extension  of  the  author's  meaning  that  we  speak  of  the 
glands  of  Brunner  as  occupying  the  termination  of  the  small  intestine,  the  stomach,  and 
even  the  large  intestine. 

The  glandulae  solitariae  present  the  appearance  of  small  rounded  granulations,  like  mil- 
let seeds,  projecting  upon  the  internal  surface  of  the  mucous  membrane,  without  any 
distinct  orifice,  and  covered  with  villi  (fig.  157) ;  they  are  found  upon  the  valvulae  con- 
niventes,  as  well  as  in  the  spaces  between  them.  Their  number  is  very  considerable  ; 
so  that  in  certain  diseases,  where  they  become  more  prominent  than  usual,  they  might 
be  mistaken  for  a  confluent  eruption.  It  is  a  mistake  to  say  that  they  diminish  in  num- 
ber from  the  upper  towards  the  lower  part  of  the  small  intestine,  the  contrary  being 
nearer  to  the  truth.  When  examined  with  the  simple  microscope,  they  have  appeared 
to  me  to  be  hollow,  and  filled  with  mucus. t 

The  agminated  follicles,  or  glandular  plexuses,  are  more  generally  knov^n  as  the  glands 
of  Peyer,  although  both  the  solitary  and  agminated  glands  were  described  by  that  anato- 
mist. Pechlin  noticed  them  under  the  name  of  vesicularum  agmina.  Willis,  Glisson, 
Malpighi,  Duvemey,  and  Wepfer  have  given  more  or  less  complete  descriptions  of  them: 
but  Peyer  (De  Glandulis  Intestinorum,  J.  C.  Peyer,  1667,  1673),  when  still  a  young  man, 
and  without  any  knowledge  of  the  work  of  Pechlin,  described  and  figured  them  under 
the  title  oi  glandula  agminatce  so  accurately  as  to  leave  nothing  to  be  desired. 

These  agminated  glands  are  arranged  in  elliptical  patches  {fig.  158),  the  long  diameter 
of  which  corresponds  with  the  direction  of  the  intestine  :  —g..  153. 

they  are  pierced  with  holes,  or  small  depressions,  so  that 
they  have  a  honeycombed  appearance ;  and  hence  has 
arisen  the  name  of  plaques  gaufries,  under  which  I  believe 
I  was  the  first  to  describe  them :  they  are  all  situated  on 
the  border  opposite  to  that  by  which  the  mesentery  is  at- 
tached to  the  intestine  ;  that  is,  along  the  convex  border 
of  the  intestine,  and  never  along  the  concave  border,  nor 
even  upon  either  side.  They  are  chiefly  found  towards  the 
end  of  the  small  intestine ;  they  become  more  and  more 
scattered  as  we  approach  the  duodenum,  in  which,  how- 
ever, Peyer  once  met  with  a  single  patch.  Their  nuniber 
varies  considerably,  twenty,  thirty,  and  even  more  having 
been  counted.  Are  they  ever  entirely  wanting  1  The  dif- 
ficulty of  detecting  them  in  some  subjects  has  led  to  their 
being  rejected  altogether,  or  considered  as  the  results  of 
a  pathological  condition  ;  but  this  opinion  is  clearly  at  va- 
riance with  observation.  Again,  these  patches  are  not 
constant  either  in  situation,  form,  or  dimensions.  Some- 
times they  assume  the  appearance  of  bands  two  or  three 
inches  in  length  {fig.  158),  and  sometimes  they  form  cir- 
cular or  irregular  clusters.  The  largest  are  found  near 
the  ileo-cffical  valve.  It  is  not  rare  to  find  the  termina- 
tion of  the  small  intestine  surrounded  by  a  circular  patch ; 
in  other  cases,  the  patches  termi- 
nate some  inches  above  the  ileo- 
■f!3cal  valve,  and  their  place  is  sup- 
jjlied  by  simple  follicles. 

*  [According  to  Dr.  Boehra  (He  Gland.  Intestm.  Struct,  penitiori),  this  is  not  tte 
case,  the  compound  glands  of  Brunner  not  existing  below  the  commencement  of  the 
jejunum.] 

t  iFig.  157  is  a  solitary  gland  magnified  ;  it  is  represented,  after  Boehm,  as  a 
closed  vesicle,  filled  with  whitish  matter,  which  contains  granules  smaller  than 
those  of  mucus.  Villi  are  seen  upon  the  free  surface  of  its  capsule,  and  it  is  sur- 
rounded by  the  crypts  of  Lieberkuhn  (the  mouths  of  which  are  indicated  by  the  ^aj^e' 
spots),  which  have  no  communication  with  the  vesicle  itself  (see  also  note,  p  370J.1 
A  A  A 


Fig.  157. 


370  SPLANCHNOLOGY. 

These  patches  are  generally  contained  in  the  substance  of  the  mucous  membrane,  to 
_p.    j.g  which  they  give  a  much  greater  density,  so  that,  in 

_     ■      ■  these  situations,  it  will  bear  to  be  scraped.     In  some 

f-  <     ^  ftases  they  appear  to  be  imbedded  in  the  fibrous  coat. 

pi;  V,.  They  should  be  examined  both  from  the  external  and 

f'  :rwmMfim  internal  surfaces  of  the  mucous  membrane.*    When 

y  '.^millll  they  are  filled  with  their  secreted  fluid,  and  are  exam- 

ined by  transmitted  light,  they  may  be  compared  to  the 
vesicles  in  the  skin  of  an  orange  :  this  observation  may 
be  easily  made  in  the  day.  They  evidently  consist  of 
collections  of  glands,  exactly  resembhng  the  solitary 
glands  {fig.  159).  Each  depression  appears  to  be  the 
orifice  of  one  of  the  follicles,  which  are  quite  independ- 
ent of  each  other ;  so  that  we  sometimes  find  two  or 
three  altered  in  the  middle  of  a  patch,  which  is  other- 
wise perfectly  healthy.  Lastly,  viUi  are  found  upon  the 
patches  of  the  glandulse  agminatae  :  they  occupy  the  in- 
tervals between  the  depressions.! 
The  Follicles  or  Corjruscules  of  Lieberkuhn. — Lieberkuhn  speaks,  also,  of  innumerable, 
rounded,  whitish  foUicles,  which  are  seen  between  the  villi,  and  of  corpuscules  which  are 
visible  between  these  follicles.  He  calculates  that  there  are  eighty  follicles  for  eighteen 
villi,  and  eight  corpuscules  for  each  follicle.  I  am  disposed  to  think  that  these  follicles 
and  corpuscules,  which  have  never  been  seen  excepting  by  the  microscope,  should  be  refer- 
red to  those  globules  which  are  reveededin  all  the  tissues  by  the  aid  of  a  magnifying  power.  | 
The  Vessels  and  Nerves. — ^All  the  arteries  of  the  small  intestine,  properly  so  called,  are 
branches  of  the  superior  mesenteric.  They  are  very  numerous.  Those  of  the  duodenum 
arise  from  the  hepatic.  The  branches  from  the  superior  mesenteric  are  remarkable  for 
the  numerous  anastomotic  loops  which  they  form  before  reaching  the  intestine,  for  their 
flexuous  course  within  its  coats,  and  for  the  series  of  vascular  layers  formed  by  them 
between  the  peritoneal  and  muscular,  the  muscular  and  fibrous,  and  the  fibrous  and  mu- 
cous coats.  The  last  layer  forms  a  very  complicated  network,  from  which  the  vessels 
of  the  mucous  membrane  are  derived.  The  veins  are  much  larger  than  the  arteries,  and 
present  a  similar  arrangement,  except  in  regard  to  the  flexuous  course,  which  is  peculiar 
to  the  arteries  ;  they  constitute  the  superior  mesenteric  vein,  which  is  one  of  the  prin- 
cipal branches  that  contribute  to  form  the  vena  portae. 

The  lymphatic  vessels  are  of  two  kinds,  viz.,  lacteals  and  lymphatics,  properly  so  called  ; 
they  both  enter  the  numerous  lymphatic  glands,  situated  in  the  mesentery ;  those  which 
belong  to  the  duodenum  enter  the  glands  above  the  pancreas. 
The  nerves  are  derived  from  the  solar  plexus. 

The  development  of  the  small  intestine  will  be  noticed  in  conjunction  with  that  of  the 
large  intestine. 

Uses. — Chylification,  i.  e.,  the  transformation  of  the  chyme  into  chyle,  is  effected  in  the 
duodenal  portion  of  the  small  intestine.  The  essential  agents  of  this  process  are  the 
bile  and  the  pancreatic  fluid.  In  the  remainder  of  the  small  intestine  (the  jejunum  and 
ileum),  the  absorption  of  the  chyle  takes  place.  The  numerous  convolutions,  the  valvu- 
lae  conniventes,  and  the  villi,  all  tend  to  increase  the  extent  of  the  absorbing  surface. 
The  products  of  exhalation  and  of  follicular  secretion  serve  to  complete  the  digestive 
process.  The  contents  of  the  bowels  are  forced  along  by  the  shortening  of  the  longitu- 
dinal, and  the  contraction  of  the  circular  fibres,  the  latter  producing  the  vermicular  mo- 
tion of  the  intestines. 

The  Large  Intestine. 

The  large  intestine  is  that  part  of  the  alimentary  canal  which  extends  from  the  end  oi 
the  small  intestine  {d,fig.  139)  to  the  anus  (i).  It  commences  in  the  right  iliac  region 
{c,fig.  161),  and  passes  upward  (a)  as  far  as  the  right  hypochondrium ;  then,  having 
reached  the  liver,  it  makes  a  sharp  flexure  (the  right  or  hepatic  flexure),  and  proceeds 

*  [Their  contents  are  sometimes  transparent,  and  tliey  are  then  very  difficult  of  detection.] 

filn  fig.  169,  representing  part  of  a  patch  of  Peyer's  glands  magnified,  are  seen  some  of  the  elevated  white 
bodies  described  by  Boehra  as  resembling  the  solitary  glands,  except  in  not  generally  having  any  villi  situated 
directly  upon  them.  Each  is  surrounded  by  a  zone  of  dark  points,  the  elongated  openings  of  the  crypts  of 
Lieberkuhn.  Many  of  these  crypts  are  also  seen  scattered  irregularly  between  the  numerous  villi ;  none  of 
them  communicate  vpith  the  interior  of  the  whitish  bodies,  in  which,  whether  solitary  or  agminated,  Boehm 
could  discover  no  opening,  at  least,  not  in  a  healthy  human  intestine.  He  considers  them,  therefore,  to  be  closed 
vesicles,  not  follicles. 

More  recently,  however,  Krause  has  observed  that,  in  the  pig's  intestine,  they  are  occasionally  open,  independ- 
ently of  disease  ;  and  Dr.  Allen  Thomson  has  lately  made  a  similar  obsen'ation  in  reference  both  to  the  pig 
and  to  the  human  subject.] 

i  [The  follicles  or  crypts  of  Lieberkuhn  are  tubes  placed  more  or  less  perpendicularly  to  the  surface  of  the 
mucous  membrane,  like  those  in  the  stomach,  but  situated  more  widely  apart ;  their  open  mouths  are  seen 
scattered  over  the  whole  surface  of  the  membrane,  or  collected  around  the  solitary  and  agminated  glands  (figt 
157,  159).  The  corpuscules  {corpora  albicantia),  described  by  the  same  observer  as  being  situated  in  the  bot- 
tom of  the  crypts,  are  probably  collections  of  desquamated  epithelium  within  them.] 


THE    INTESTINES.  371 

iransTersely  (t)  from  the  right  to  the  left  side  {transverse  arch  of  the  colon) ;  in  the  left 
h3T)Ochondrium,  below  the  spleen,  it  again  makes  a  sharp  bend  and  becomes  vertical  (d), 
(left  or  splenic  flexure).  In  the  left  iliac  region  (/)  it  is  twice  bent  upon  itself,  hke  the  Ro- 
man letter  S  {iliac  or  sigmoid  flexure),  and  it  then  dips  into  the  pelvis  (r),  and  terminates 
at  the  anus. 

The  large  intestine,  therefore,  describes  within  the  abdomen  a  nearly  complete  circle, 
which  surrounds  the  mass  of  convolutions  of  the  small  intestine ;  and  it  occupies  the 
right  and  left  iliac  regions,  the  right  and  left  lumbar,  the  base  of  each  hypochondriac, 
and  the  adjacent  borders  of  the  epigastric  and  umbilical  regions.  Although  it  is  much 
more  firmly  fixed  in  its  place  than  the  small  intestine,  and  is,  therefore,  less  liable  to 
displacement,  yet  it  presents  some  varieties  in  length  and  curvature  which  have  a  con- 
siderable influence  over  its  position.  The  large  intestine  is  more  deeply  situated  than 
the  small  in  one  part  of  its  extent,  but  in  another  is  at  least  quite  as  superficial. 

From  its  long  course,  and  from  the  different  relations  piesented  by  its  diflferent  parts, 
it  has  been  divided  into  the  ccecum,  the  colon,  which  is  itself  subdivided  into  several 
parts,  and  the  rectum. 

Dimensions. — The  IcTigth  of  the  large  intestine  is  four  or  five  feet,  and,  compared  with 
the  small  intestine,  is  as  one  to  four  ;  but  it  varies  considerably,  rather,  it  would  seem 
to  me,  from  the  eflfects  of  repeated  distension,  than  from  any  original  conformation  ;  for 
it  may  be  easUy  imagined  that  the  bowel  cannot  be  distended  transversely  without  lo- 
sing somewhat  in  length,  and  that,  on  returning  to  its  former  diameter,  it  must  be  elon- 
gated in  proportion  to  the  distension  it  had  previously  undergone.  The  large  intestine 
has  also  generally  appeared  to  me  longer  in  persons  advanced  in  age  than  in  adults. 

Its  caliber  or  diameter  usually  exceeds  that  of  the  small  intestine,  but  may  become  so 
reduced  that  the  gut  resembles  a  hard  cord,  about  the  size  of  the  little  finger.  In  other 
cases  it  is  so  large  that  it  occupies  the  greatest  part  of  the  abdominal  cavity :  this  is  ob- 
served in  tympanitic  distension  of  the  large  intestine.  It  is  not  of  uniform  caliber 
throughout,  as  the  following  measurements  will  show.  The  circumference  of  the  caecum, 
moderately  distended,  and  taken  immediately  below  the  ileo-caecal  valve,  was  found  to 
be  eleven  inches  and  three  lines  in  one  subject,  and  nine  inches  and  a  half  in  another ; 
the  right  colon  in  the  loins  and  the  right  half  of  the  arch  were  eight  inches  and  nine 
lines  in  the  first,  and  five  inches  some  lines  in  the  second  subject.  The  circumference 
of  the  left  half  of  the  arch  of  the  colon,  and  of  the  left  lumbar  colon,  was  six  inches  in 
the  first  and  five  inches  and  a  half  in  the  second.  The  circumference  of  the  sigmoid 
flexure  was  five  inches  and  a  quarter ;  that  of  the  rectum  was  three  inches  until  near 
its  termination,  where  it  presented  a  dilatation  four  inches  in  circumference  in  one,  and 
five  inches  in  the  other  subject. 

It  follows,  therefore,  that  the  large  intestine,  like  the  small,  has  an  infiindibuliform 
shape  ;  it  resembles,  indeed,  two  ftmnels,  the  base  of  the  one  corresponding  to  the 
caecum,  and  its  apex  to  the  sigmoid  flexure,  while  the  base  of  the  other  is  at  the  dilated 
portion  of  the  rectum,  and  its  apex  is  apphed  to  that  of  the  first.  It  is  probable  that  this 
infundibuliform  arrangement  has  some  reference  to  the  passage  of  the  faecal  matters. 

It  also  follows  that  there  is  no  uniform  relation  between  the  diameters  of  the  different 
portions  of  the  large  intestine  :  thus,  a  very  large  caecum  and  ascending  colon  may  co- 
exist with  a  small  descending  colon  In  some  cases  we  find  in  the  large  intestine  con- 
siderable dilatations,  separated  from  each  other  by  such  constrictions  that  the  caliber 
of  the  corresponding  part  of  the  gut  is  obliterated.  These  strangulations  from  a  con- 
traction of  the  circular  fibres  are  very  different  from  those  produced  by  organic  diseases  : 
they  probably  take  place  during  life,  and  may  account  for  the  affection  known  as  the 
windy  colic.  In  some  chronic  diseases,  accompanied  with  diarrhcea,  the  large  intestine, 
contracted  and  containing  no  gases,  is  not  as  large  as  the  small  intestine. 

The  CcEcum. — The  caecum  (e,  fig.  139),  so  named  because  it  resembles  a  cul-de-sac,  is 
the  first  part  of  the  large  intestine  The  existence  of  a  caecum  is  one  of  the  numerous 
indications  of  the  line  of  separation  between  the  large  and  the  small  intestine.  Its  up- 
per boundary  is  altogether  arbitrary ;  it  is  determined  by  a  horizontal  plane  intersecting 
it  immediately  above  the  insertion  of  the  small  intestine.  It  is  single  in  the  human  sub- 
ject, but  is  double  in  some  species  of  animals.  It  is  situated  {c,fig.  161)  in  the  right  iliac 
fossa,  and  occupies  it  almost  entirely.  It  is  one  of  the  most  fixed  portions  of  the  ali- 
mentary canal,  for  the  peritonemn  merely  passes  in  front  of  it,  and  binds  it  down  into 
the  iliac  fossa.  It  is  not,  however,  so  firmly  fixed  in  all  subjects ;  it  is  often  enveloped 
by  the  peritoneum  on  all  sides,  and  floats,  as  it  were,  in  the  region  which  it  occupies,  its 
capability  of  motion  depending  on  the  looseness  of  the  right  lumbar  mesocolon.  This 
arrangement  of  the  peritoneum  is  not  necessary,  however,  to  explain  the  great  amoun 
of  displacement  which  the  caecum  undergoes  in  certain  cases.  It  is  not  uncommon  to 
find  it  in  the  cavity  of  the  pelvis :  it  occasionally  enters  into  the  formation  of  herniae 
and,  what  is  somewhat  remarkable,  it  has  been  at  least  as  frequently  found  in  hernia 
upon  the  left  as  upon  the  right  side. 

Its  direction,  which  is  in  general  the  same  as  that  of  the  ascending  colon,  is  not  alway 
vertical  a.s  may  be  seen  by  examining  a  moderately-distended  intestine,  but  it  pass* 


379"  SPLANCHNOLOGY. 

obliquely  upward  and  to  the  right  side,  so  that  it  forms  with  the  colon  an  obtuse  angle 
projecting  on  the  right  side  ;  and  I  have  even  seen  it  form  a  right  angle  with  the  colon. 
This  arrangement,  connected  with  the  obliquity  of  the  plane  of  the  iliac  fossa,  explains 
why,  when  its  attachments  are  relaxed,  it  has  less  tendency  to  be  displaced  towards  the 
right  inguinal  ring  and  femoral  arch  than  to  the  same  parts  on  the  left  side.  In  some 
subjects,  the  caecum  and  its  vermiform  appendix  are  applied  to  the  lower  part  of  the 
small  intestine,  so  that  the  caecum  and  the  neighbouring  part  of  the  colon  describe  a 
curve,  the  concavity  of  which  embraces  the  lower  end  of  the  ileum. 

In  size  it  is  generally  larger  than  the  portion  of  the  intestine  which  succeeds  it :  this, 
perliaps,  depends  less  upon  its  primitive  conformation  than  upon  the  accumulation  of 
faecal  matters  resulting  from  the  inclined  position  of  this  intestine,  and  from  the  direc- 
tion in  which  its  contents  are  moved.  It  may  be  said,  as  a  general  rule,  that,  next  to 
the  stomach,  the  caecum  is  the  largest  part  of  the  alimentary  canal.  There  are  many 
individual  varieties  in  the  length  and  capacity  of  this  intestine,  in  which  the  faecal  mat- 
ters are  liable  to  be  retained.  These  accumulations  occasion  great  pain ;  they  have 
been  much  studied  lately,  and  have  been  often  mistaken  for  inflammations.  The  caecum 
is  very  shghtly  developed  in  carnivora,  but,  on  the  other  hand,  it  is  very  large  in  her- 
bivora. 

Figure. — ^The  caecimi  is  a  sort  of  rounded  ampulla,  all  the  diameters  of  which  arc 
nearly  equal ;  it  is  also  sacculated  like  the  rest  of  the  large  intestine.  Upon  it  we  ob- 
serve the  conamencement  of  the  three  longitudinal  bands,  which  I  have  already  noticed  : 
of  these,  the  anterior  is,  in  the  caecum,  twice  as  broad  as  either  of  the  two  posterior  ; 
some  folds  of  peritoneum,  loaded  with  fat,  which  are  called  fatty  appendages  {appendices 
epiploica) ;  and,  lastly,  some  protuberances,  separated  by  parallel  depressions,  an  ar- 
rangement which  exists  in  the  colon  also,  and  is  produced  by  the  longitudinal  bands. 

Relations. — In  front,  the  caecum  is  in  relation  with  the  abdominal  parietes,  through 
which  it  can  be  felt  when  it  is  distended  with  gases  or  faecal  matters.  When  the  cae- 
cum is  collapsed,  the  small  intestine  is  often  interposed  between  it  and  the  parietes  of 
the  abdomen. 

Behind,  it  rests  upon  the  iliacus  muscle,  from  which  it  is  separated  by  the  lumbo-iliac 
fascia.  The  cellular  tissue  uniting  it  to  this  aponeurosis  is  extremely  loose,  and,  there- 
fore, offers  no  opposition  to  displacement  of  the  intestine.  When  the  peritoneum  forms 
a  complete  covering  for  the  caecum,  that  intestine  is,  of  course,  in  indirect  relation  with 
the  iliacus.  The  vermiform  appendix  is  often  turned  back  behind  the  caecum.  On  the 
inside,  the  caecum  receives  the  small  intestine  ;  the  angle  at  which  they  unite  (the  ileo- 
csecal  angle)  varies  much.  Sometimes  the  small  intestine  is  inserted  at  a  right  angle  ; 
most  commonly  the  angle  of  incidence  is  obtuse  above  and  acute  below  {fig.  160).  Some- 
times the  ileum,  instead  of  passing  upward,  is  directed  downward,  and  then  the  angle 
of  incidence  is  changed.  A  circular  depression  indicates  the  limit  between  the  two  in- 
testines. Below,  upon  the  free  extremity  or  cul-de-sac  of  the  caecum,  is  seen  the  \^r- 
miform  appendix  {v),  situated  behind  and  on  the  left  side,  a  few  lines  below  the  ileo- 
caecal  angle. 

The  arrangement  of  the  internal  or  mucous  surface  of  the  caecum  is  in  accordance  with 
that  of  its  external  surface  :  thus,  three  projecting  ridges  correspond  with  the  three  lon- 
gitudinal bands  ;  some  cavities  or  pouches  with  the  protuberances ;  and  some  transverse 
projecting  folds,  forming  incomplete  septa,  which  are  easily  seen  in  a  dried  specimen, 
correspond  with  the  parallel  depressions.  Upon  this  surface,  to  the  left  and  a  little  be- 
hind, we  also  find  the  ileo-caecal  valve  (a  b,fig.  160),  and  the  orifice  (o)  of  the  vermiform 
appendix  (»). 

The  Ileo-caecal  Valve. — This  is  also  called  the  valve  of  Bauhin,  from  the  name  of  the  anat- 
omist to  whom  its  discovery  is  attributed,  although  it  had  been  described  before  his  time. 
To  obtain  a  perfect  knowledge  of  it,  it  should  be  examined  upon  a  fresh  specimen  under 
water,  and  also  upon  an  inflated  and  dried  intestine. 

In  a  fresh  specimen,  when  viewed  from  the  caecum,  it  presents  the  appearance  of  a 
projecting  cushion,  oblong  from  before  backward,  and  fissured  in  the  same  direction.  It 
is  a  membranous  and  movable  cushion,  and  was  incorrectly  compared  by  Riolanus  to  the 
pyloric  ring.  It  has  two  lips  and  two  commissures  ;  the  two  lips  are  in  contact,  except 
during  the  passage  of  the  contents  of  the  bowels.  Two  folds,  proceeding  from  the  two 
commissures,  one  of  which  is  anterior  and  the  other  posterior,  are  lost  upon  the  corre- 
sponding surfaces  of  the  intestine.  The  posterior  fold  is  much  longer  than  the  anterior ; 
Morgagni  called  them  ihefrana  of  the  valve.  When  viewed  from  the  ileum,  it  presents 
the  appearance  of  a  funnel-shaped  cavity,  directed  upward  and  to  the  right  side. 

In  a  dried  intestine,  the  ileo-caecal  valve  is  seen  to  consist  of  two  prominent  valvular 
segments,  projecting  into  the  caecum,  so  as  to  form  an  angular  ridge.  The  upper,  or  ileo- 
colic segment  {b,fig.  160),  is  horizontal ;  the  lower,  or  ilco-ccecal  (a),  forms  an  inclined  plane 
of  about  45°,  and  both  are  parabolic.  The  upper  segment  is  fixe  J  by  its  adherent  convex 
border  to  the  semicircular  line,  along  which  the  upper  part  of  the  tube  of  the  ileum  is 
united  with  the  colon  ;  the  adherent  border  of  the  lower  segment,  \^  hich  is  also  convex, 
is  continuous  with  the  semicircular  hue  of  junction  between  the  lower  half  of  the  ileum 


THE   INTESTINES.  373 

and  the  caecum.  The  free  borders  of  the  segments  are  directed  to- 
wards the  right  side,  and  are  semilunar ;  they  are  united  at  their  ex- 
tremities, but  in  the  middle  leave  between  them  (between  a  and  h) 
an  opening  like  a  buttonhole,  which  becomes  narrower  as  the  intes- 
tine is  more  distended.  The  diameter  of  this  opening  is  in  proportion 
to  that  of  the  small  intestine.  The  free  border  of  the  lower  segment 
is  more  concave  than  that  of  the  upper.  When  examined  from  the 
ileum,  the  valve  presents  an  angular  excavation  exactly  correspond- 
ing to  the  projecting  edge  found  in  the  cavity  of  the  large  intestine. 
The  lower  surface  of  the  upper  valvular  segment  is  slightly  concave  ; 
the  corresponding  surface  of  the  lower  segment  is  slightly  convex. 

This  double  ileo-caecal  valve  differs  widely  from  the  ring  of  the  py- 
lorus ;  it  offers  no  obstruction  to  the  passage  of  the  contents  of  the 
small  into  the  large  intestine  ;  but  in  ordinary  cases,  it  will  not  per-  " 

mit  their  regurgitation  from  the  latter  into  the  former.  The  lower  or  ileo-caecal  segment 
is  elevated  so  as  to  prevent  reflux  from  the  caecum,  and  the  ileo-colic  segment  becomes 
depressed,  and  opposes  any  return  of  the  contents  of  the  colon.  Still,  from  a  great  num- 
ber of  experiments  which  I  have  performed  on  this  subject,  I  am  satisfied  that  both  wa- 
ter and  air  injected  into  the  large  intestine  most  frequently  overcome  the  resistance  offer- 
ed by  this  valve,  though  with  different  degrees  of  facility  in  different  subjects.  This  re- 
gurgitation, however,  only  takes  place  with  gaseous  or  liquid  matters  ;  such  as  have  a 
greater  degree  of  consistence  cannot  pass  back,  and  therefore  the  reflux  of  faecal  matter 
is  impossible.* 

Structure. — ^The  structure  of  the  ileo-caecal  valve  was  perfectly  demonstrated  by  Albi- 
nus.  If  we  follow  his  example,  and  remove  the  peritoneal  coat  from  a  distended  intes- 
tine, at  the  point  where  the  ileum  enters  the  large  bowel,  we  shall  at  once  perceive  most 
distinctly  that  the  small  intestine  seems  to  sink  in  there  ;  and  if,  by  means  of  careful  and 
gradual  force,  we  attempt  to  disengage  it  from  the  large  intestine,  it  may  be  drawn  out, 
as  it  were,  from  the  colon  to  the  length  of  an  inch  or  an  inch  and  a  half;  and  then,  on 
inspecting  the  inside  of  the  large  intestine,  we  shall  find  that  the  valve  has  altogether 
disappeared,  and  that  the  ileum  communicates  with  the  caecum  and  colon  by  a  large  ap- 
erture. 

The  precise  structure  of  the  valve  is  as  follows  :  it  is  composed  of  the  circular  muscu- 
lar fibres  of  the  ileum,  which  are  prolonged  as  far  as  its  free  edge  ;t  of  the  fibrous  coat, 
and  of  the  mucous  membrane.  A  similar  fact  has  been  observed  regarding  this  mucous 
membrane  to  one  we  have  already  several  times  noticed  in  describing  the  alimentary  ca- 
nal, viz.,  a  sudden  change  in  its  character  opposite  the  free  margin  of  the  valve.  That 
portion  of  the  membrane  which  lines  the  surface  turned  towards  the  large  intestine  has 
all  the  characters  of  the  mucous  membrane  of  that  bowel,  while  that  lining  the  surface 
directed  towards  the  ileum  has  those  of  the  mucous  membrane  of  the  small  intestine. 
The  limit  between  them  is  generally  observed  in  diseases. 

The  Appendix  Vermiformis. — The  appendix  vermiformis  {v,figs.  139,  160,  161),  so  na- 
med from  its  resemblance  to  an  earth-worm,  commences  at  the  posterior  lower  and  left 
portion  of  the  caecum,  of  which  it  may  be  considered  an  appendage  {the  cacal  appendix) ; 
it  resembles  a  small,  hollow,  and  very  narrow  cord  {duodecies  jiascente  colo  angustior,  says 
Haller).  In  length  and  in  direction,  it  presents  much  variation :  its  length  is  from  one  to 
six  inches.  It  is  somewhat  wider  at  its  point  of  junction  with  the  cascum  than  in  any 
other  part,  and  is  in  general  about  the  diameter  of  a  goose-quill. 

Its  direction  is  sometimes  vertically  downward,  sometimes  upward,  and  often  tortuous. 
I  have  found  it  spiral,  and  at  other  times  contained  in  the  substance  of  the  mesentery, 
parallel  to  the  ileum,  and  only  free  at  its  extremity.  In  some  subjects  it  is  funnel-sha- 
ped, widening  out  to  become  continuous  with  the  caecum,  which,  in  such  cases,  is  very 
narrow.  Its  situation  and  relations  are  equally  variable.  Thus,  most  conmionly,  it  oc- 
cupies the  right  iliac  fossa,  near  the  brim  of  the  pelvis  :  it  is  attached  to  the  caecum  and 
to  the  iliac  fossa  by  a  triangular  or  falciform  fold  of  the  peritoneum,  which  extends  only 
to  one  half  of  its  length,  and  allows  it  a  greater  or  less  capability  of  movement.  It  is  still 
more  movable  when  it  is  entirely  surrounded  by  the  peritoneum,  and  has  no  mesentery. 
From  this  it  may  be  conceived  that  it  may  enter  into  the  formation  of  herniae,  and  may 
be  twisted  around  a  knuckle  of  the  small  intestine,  so  as  to  cause  strangulation.    It  is 

*  Nevertheless,  if  we  consider  that  the  large  intestine  must  always  be  very  much  distended  in  order  to  pro- 
duce a  reflux  of  gases  and  liquids,  it  may  be  questioned  whether  the  passage  of  gaseous  or  liquid  matters  from 
the  large  to  the  small  intestine  can  take  place  during  life.  I  have  been  able  to  determine  the  mechani.sm  of 
the  resistance  oflfered  by  the  valve  from  the  effects  of  distension.  The  two  segments  are  turned  back,  the 
lower  one  upward,  and  the  upper  one  downward  ;  their  corresponding  surfaces  become  convex,  and  they  are 
pressed  together  the  more  and  more  forcibly  in  proportion  to  the  amount  of  distension.  In  some  subjects  dis- 
tension may  be  carried  so  far  as  to  rupture  the  longitudinal  bands,  and  yet  not  overcome  the  obstacle.  In 
most  cases,  the  free  edge  of  the  lower  segment  glides  from  right  to  left  under  the  upper  one,  which  remaina 
immovable  ;  and  the  gas  and  liquids  escape  with  more  or  less  facility  according  to  the  degree  of  disturbance 
in  the  parts. 

t  I  The  longitudinal  muscular  fibres  and  the  peritoneal  coat  pass  directly  from  the  small  to  the  large  intes- 
tine, without  entering  into  the  formation  of  the  valve.] 


374 


SPLANCHNOLOGY. 


often  turned  back  behind  the  ascending  colon  between  that  intestine  and  the  kidney :  in 
one  case  of  this  kind,  I  found  the  free  extremity  of  the  appendix  in  contact  with  the  lower 
surface  of  the  liver.  I  have  also  once  seen  it  turned  up  behind  the  lower  end  of  the 
-amall  intestine,  and,  at  another  time,  embracing  that  bowel  in  front.  None  of  these  dif- 
*  ferences,  however,  depend  on  the  situation  of  its  point  of  attachment  to  the  csecum, 
which  is  always  on  the  left  side,  below  and  behind  the  cul-de-sac,  at  a  short  distance 
from  the  ileo-caecal  valve. 

When  divided  lengthwise,  the  cavity  within  it  is  seen  to  be  so  narrow  that  the  walls 
are  always  in  contact.  A  small  quantity  of  mucus  is  found  in  it,  and  it  often  contains 
small  scybala  ;  cherry-stones  and  shot  have  also  been  found  in  it.  The  whole  of  its 
internal  surface  has  a  honeycomb  appearance,  like  that  at  the  lower  end  of  the  small 
intestine.*  A  valve  of  different  size  in  different  subjects,  but  never  sufficiently  large  to 
cover  the  orifice  entirely,  is  found  at  the  point  (o.  Jig.  160)  where  the  appendix  commu- 
nicates with  the  caecum.  The  cavity  of  the  appendix,  like  the  caecum,  terminates  be- 
low in  a  cul-de-sac ;  and  in  this,  which  is  extremely  narrow,  foreign  bodies  may  be 
lodged,  and  may  then  sometimes  become  the  cause  of  those  spontaneous  perforations 
which  are  occasionedly  seen.  The  uses  of  this  appendix  are  edtogether  unknown ;  in  the 
human  subject,  it  is  merely  a  vestige  of  an  important  part  in  many  animals.  Haller  says 
that  he  has  twice  seen  the  vermiform  appendix  obliterated,  i.  e.,  without  any  cavity.  I 
presume  that  this  was  the  effect  of  morbid  adhesion.  Lastly,  I  once  found  this  appendix 
as  large  as  the  index  finger,  and  two  inches  in  length  ;  its  cavity  contained  some  thick, 
transparent  mucus.  The  orifice  by  which  it  should  have  conununicated  with  the  caecum 
was  obliterated. 

The  Colon. — The  colon  {kuXvu,  to  impede,  dfg  h,fig.  139)  constitutes  almost  the  whole 
of  the  large  intestine.  It  extends  from  the  caecum  to  the  rectum,  and,  as  we  have  al- 
ready seen,  there  is  no  line  of  demarcation  between  these  different  parts.  In  the  first 
part  of  its  course  it  ascends  vertically,  then  becomes  transverse,  next  descends  vertical- 
ly, and  is  then  curved  like  the  Roman  letter  S,  and  becomes  continuous  with  the  rectum. 
From  this  long  course,  and  also  from  its  direction  and  numerous  relations,  the  colon  has 
been  divided  into  four  portions,  viz.,  the  ascending  or  right  lumbar  colon,  the  transverse  colon, 
or  arch  of  the  colon,  the  descending  or  left  lumbar  colon,  and  the  iliac  colon,  or  sigmoid  flexure. 
Each  of  these  parts  requires  a  separate  description,  at  least  with  regard  to  its  relations. 
Let  us  first  point  out  the  general  form  of  the  colon. 

The  colon  presents  a  sacculated  appearance  throughout,  which  gives  it  some  resem- 
blance to  a  chemical  apparatus,  consisting  of  a  long  series  of  aludels.  The  sacculi  of 
the  colon  are  arranged  in  three  longitudinal  rows,  separated  by  three  muscular  bands. 
Each  of  these  rows  presents  a  succession  of  enlargements  and  constrictions,  or  deep 
grooves,  placed  across  the  length  of  the  intestine.  These  enlargements  and  grooves 
are  produced  by  the  longitudinal  bands,  which,  bemg  much  shorter  than  the  intestine, 

cause  it  to  be  folded  inward  upon  itself 
at  intervals.  It  follows,  therefore,  that 
division  of  these  bands  by  means  of  a 
bistoury,  or,  rather,  their  rupture,  from 
great  distension  of  the  gut,  should  de- 
stroy this  sacculated  appearance,  and 
such,  indeed,  is  the  result  of  the  exper- 
iment ;  at  the  same  time,  the  large  in- 
testine becomes  twice  or  three  times 
as  long  as  it  was  before,  and  forms  a 
regular  cylinder,  hke  the  small  intes- 
tine. An  incontestable  proof  of  the 
relation  between  the  cells  of  the  colon 
and  the  muscular  bands,  is  the  con- 
current absence  of  both  in  a  great  num- 
ber of  animals.  Lastly,  the  three  rows 
of  sacculi  vary  much  in  different  sub- 
jects, and  also  in  different  parts  of  the 
great  intestine.  The  descending  colon 
and  the  sigmoid  flexure  have  only  two 
rows  of  sacculi,  and,  consequently,  two 
intermediate  bands.  The  sacculi  al- 
most entirely  disappear  in  the  sigmoid 
flexure. 

The  Ascending  or  Right  Lumbar  Colon 
(a,  figs.  135,  161). — This  portion  of  the 
colon  is  bounded  below  by  the  caecmn, 

*  [Nevertheless,  the  structure  of  the  mucouf 
membrane  in  the  two  situations  is  very  different 
(see  notes,  p.  3T0,  379).] 


.THE   INTESTINES.  375 

and  above  by  the  transverse  arch,  with  which  it  forms  a  right  angle,  near  the  gall-blad- 
der. It  is  more  or  less  firmly  held  in  its  place  by  the  peritoneum,  which  in  some  sub- 
jects merely  passes  in  front  of  it,  and  in  others  forms  a  fold  or  lumbar  mesocolon.  The 
ascending  and  descending  colon  may  be  included  among  the  most  fixed  portions  of  the 
alimentary  canal.  In  front  of  it  are  the  parietes  of  the  abdomen,  from  which,  excepting 
when  greatly  distended,  it  is  separated  by  the  convolutions  of  the  small  intestine.  Be- 
hind, it  is  in  immediate  relation  with  the  quadratus  lumborum  and  the  right  kidney,  no 
layer  of  peritoneum  intervening.  It  is  united  to  these  parts  externally  by  loose  cellular 
tissue.  This  relation  accounts  for  the  bursting  of  abscesses  of  the  kidney  into  the  colon, 
and  explains  the  possibility  of  reaching  the  colon  in  the  lumbar  region  without  wound- 
ing the  peritoneum.  On  the  left  side,  advantage  has  been  taken  of  this  fact  in  attempt- 
ing to  form  an  artificial  anus. 

On  the  inside  and  on  the  outside  it  is  in  relation  with  the  convolutions  of  the  small  intes- 
tine ;  and  on  the  inside  also  with  the  psoas  muscle,  and  with  the  second  portion  of  the 
duodenum. 

The  Transverse  Colon,  or  Arch  of  the  Colon. — This  (<)  is  the  longest  portion  of  the  large 
intestine  ;  it  extends  from  the  ascending  to  the  descending  colon,  from  the  right  to  the 
left  hypochondrium,  and  generally  occupies  the  adjacent  borders  of  the  epigastric  and 
umbilical  regions.  It  is  not  unfrequently  found  opposite  the  umbilicus,  and  even  in  the 
hypogastrimn.  Its  right  extremity  corresponds  to  the  gall-bladder  {g),  its  left  is  below 
the  spleen  {k).  It  describes  a  curve  having  its  convexity  directed  forward,  and  its  con- 
cavity backward ;  hence  the  name,  arch  of  the  colon.  In  some  subjects  it  is  two  or  three 
times  its  ordinary  length,  and  hence  it  presents  various  inflections.  I  have  seen  its 
middle  portion  descending  as  low  eis  the  umbilical  or  hypogastric  region,  and  even  reach- 
ing the  brim  of  the  pelvis ;  in  other  cases  it  descends  parallel  to,  and  on  the  inner  side 
of,  the  ascending  colon,  and  then  passes  upward  again,  or  it  describes  curves  of  different 
extent.  The  arch  of  the  colon  is  supported  by  a  very  remarkable  fold  of  peritoneum, 
called  the  transverse  mesocolon,  which  forms  a  horizontal  septum  between  the  small  in- 
testine below,  and  the  stomach,  the  liver,  and  the  spleen  above.  The  extent  of  this  fold, 
which  is  one  of  the  largest  of  all  those  formed  by  the  peritoneum,  explains  the  great 
freedom  of  the  movements  of  the  transverse  colon,  which,  next  to  the  small  intestine, 
is  the  part  of  the  alimentary  canal  most  frequently  found  in  hernia. 

Relations. — Above,  it  has  relations  with  the  liver  (Z),  which  generally  presents  a  shght 
depression,  corresponding  to  the  angle  formed  by  the  ascending  and  transverse  colon  ; 
with  the  gall-bladder  (£),  whence  the  discoloration  of  the  right  extremity  of  the  arch 
from  the  bile ;  it  is  not  rare  to  find  the  gall-bladder  opening  into  the  colon  ;  with  the 
stomach  («),  which  projects  in  front  of  it  when  distended,  but  is  separated  from  it  by  a 
considerable  interval  when  empty ;  and,  lastly,  with  the  lower  extremity  of  the  spleen 
{k).  The  two  anterior  layers  of  the  great  omentum,  which  proceed  from  the  greater 
curvature  of  the  stomach,  pass  over  the  arch  of  the  colon  without  adhering  to  it.  I  have 
seen  a  large  loop  of  the  arch  of  the  colon  interposed  between  the  liver  and  the  diaphragm. 
Below,  the  arch  of  the  colon  corresponds  to  the  convolutions  of  the  small  intestine  {fig. 
155).  In  front,  it  corresponds  to  the  parietes  of  the  abdomen,  beneath  which  it  may 
sometimes  be  felt  when  distended  with  gas.  It  is  separated  from  them  by  the  two  an- 
terior layers  of  the  great  omentum.  The  two  posterior  layers  of  the  great  omentum  are 
given  off  from  the  middle  of  its  anterior  border.  Behind,  it  gives  attachment  to  the 
transverse  mesocolon. 

The  Descending  or  Left  Lumbar  Colon. — The  descending  colon  {d,figs.  155, 161)  so  close- 
ly resembles  the  ascending  portion,  both  in  situation  and  relations,  that  we  can  only  re- 
fer to  what  has  been  already  stated.  We  must  observe,  however,  that  it  is  more  deeply 
situated  above  than  the  ascending  colon,  and  that  it  is  of  less  size.  Advantage  has  been 
taken  of  its  immediate  relations  behind,  with  the  quadratus  lumborum,  in  the  operation 
for  artificial  anus  in  cases  of  imperforate  rectum.  It  is  preferred,  for  this  purpose,  to 
the  ascending  colon,  simply  from  its  proximity  to  the  anus. 

The  Iliac  Portion,  or  Sigmoid  Flexure,  of  the  Colon. — The  sigmoid  flexure  of  the  co- 
lon {f,Jlgs.  155,  161)  is  situated  in  the  left  iliac  fossa,  and  is  continuous  below  with  the 
rectum.  The  line  of  demarcation  between  it  and  the  descending  colon  is  determined  by 
the  commencement  of  a  fold  of  peritoneum,  called  the  iliac  mesocolon,  or,  rather,  by  the 
change  in  the  direction  of  the  large  intestine,  as  it  appears  to  detach  itself  from  the  pa- 
rietes of  the  abdomen,  opposite  the  crest  of  the  ilium.  It  is  continuous  with  the  rectum 
at  the  point  where  it  dips  into  the  pelvis,  opposite  the  left  sacro-iliac  symphysis.  But,  as 
it  often  happens  that  the  lower  portion,  or  even  the  whole  of  the  sigmoid  flexure,  is  con- 
tained in  the  cavity  of  the  pelvis,  it  may  be  understood  that  such  a  definition  is  not  precise. 

It  is  retained  in  its  place  by  a  very  loose  fold  of  peritoneum,  called  the  iliac  mesocolon, 
and  therefore,  in  some  measure,  partakes  of  the  mobility  of  the  small  intestine.  It  has 
been  found  in  almost  all  the  regions  of  the  abdomen,  but  especially  in  the  sub-umbilical 
zone.  It  has  been  seen  in  the  umbilical  region,  its  first  curvature  reaching  even  to  the 
liver.  I  have  met  with  a  case  in  which  the  sigmoid  flexure  extended  upward,  and  the 
arch  of  the  colon  downward  to  the  umbilicus,  so  that  they  came  in  contact  with  each  oth. 


376  SPLANCHNOLOGY. 

er  ;  the  large  intestine,  therefore,  corresponded  with  the  whole  anterior  region  of  the 
abdomen,  the  sigmoid  flexure  alone  occupying  the  umbilical,  the  hypogastric,  and  the 
left  iliac  region. 

Should  the  following  disposition,  which  I  have  met  with  several  times,  be  regarded  as 
accidental  or  congenital  1  Commencing  from  the  descending  colon,  the  sigmoid  flexure 
passed  transversely  from  the  left  to  the  right  side,  on  a  level  with  the  brim  of  the  pelvis 
as  far  as  the  right  iliac  fossa,  below  the  caecum,  which  it  turned  upward  in  one  case,  and 
pushed  in  front  of  itself  in  another  ;  the  sigmoid  flexure  then  described  its  two  curves 
either  in  the  right  iliac  fossa  or  in  the  pelvis.  These  cases,  in  which  the  sigmoid  flex- 
ure of  the  colon  alone  is  transposed,  must  be  carefully  distinguished  from  general  trans- 
position of  the  viscera. 

The  most  peculiar  character  of  the  sigmoid  flexure  is  its  direction.  It  passes  at  first 
upward,  in  an  opposite  direction  to  the  descending  colon,  then  descends  vertically,  and 
then,  curving  again,  passes  to  the  right  or  to  the  left,  forward  or  backward,  and  becomes 
continuous  with  the  rectum  (r),  (the  iliac  flexure).  These  several  flexures,  however,  vai7 
exceedingly :  I  have  seen  them  very  shght ;  but  then  the  upper  or  free  portion  of  the 
rectum  was  found  decidedly  flexuous ;  and,  indeed,  it  is  difficult  to  ascertain  whether 
such  flexures  belong  to  the  rectum  or  to  the  displaced  sigmoid  flexure.  •  There  can  be 
no  doubt  that  this  double  curve  of  the  colon  is  connected  with  its  uses  as  a  receptacle 
for  fajcal  matters. 

The  size  of  the  sigmoid  flexure  varies  considerably.  In  a  case  of  imperforate  anus  in 
an  infant,  which  lived  twenty  days,  it  became  enormously  distended.  Retention  of  the 
faeces  in  the  adult  seldom  causes  so  proportionally  great  an  accumulation  in  the  sigmoid 
flexure  :  the  rectum  is  almost  entirely  the  seat  of  the  accumulation. 

Relations. — The  sigmoid  flexure  corresponds  to  the  abdominal  parietes  in  front.  When 
empty,  its  relations  with  the  latter  are  indirect,  in  consequence  of  the  interposition  of 
some  convolutions  of  the  small  intestine ;  when  it  is  distended,  they  are  inmiediate ; 
and  hence  we  are  recommended  to  make  an  artificial  anus  in  the  sigmoid  flexure  of  the 
colon,  in  cases  where  the  rectum  is  imperforate.  It  is  in  contact  behind  with  the  iliac 
fossa,  to  which  it  is  fiLxed  by  the  mesocolon  :  hence  it  can  be  easily  compressed  and  ex- 
plored by  the  fingers,  for  the  purpose  of  detecting  hardened  masses  of  faeces.  In  the 
rest  of  its  circumference  it  is  in  relation  with  the  convolutions  of  the  small  intestine. 

The  Internal  Surface  of  the  Colon. — On  the  internal  surface  of  the  colon  are  seen  three 
longitudinal  ridges,  corresponding  to  the  three  muscular  bands  on  its  external  surface  ; 
three  intermediate  rows  of  sacculi,  the  concavities  of  which  agree  exactly  with  the  pro- 
tuberances on  the  external  surface ;  and,  lastly,  numerous  ridges  or  incomplete  septa, 
dividing  the  cells  of  each  row  from  one  another,  and  improperly  called  valves ;  they  cor- 
respond to  the  grooves  or  depressions  on  the  external  surface.  In  order  to  comprehend 
the  arrangement  of  the  cells  and  the  intervening  septa,  we  must  examine  the  large  in- 
testine when  moderately  distended  and  dried.  If  the  muscular  bands  have  been  previ- 
ously divided,  the  cells  and  septa  disappear. 

The  internal  sacculi,  as  well  as  the  external  protuberances,  vary  much  in  different  in- 
dividuals, and  even  in  diflerent  parts  of  the  same  colon.  Thus,  there  are  generally  only 
two  rows  in  the  descending  colon  and  the  sigmoid  flexure,  because  there  are  only  two 
muscular  bands  in  those  parts.  Sometimes,  indeed,  there  are  no  cells  in  the  sigmoid 
flexure.  Lastly,  the  internal  surface  of  the  large  intestine  presents  some  irregular  folds, 
which  are  completely  effaced  by  distension. 

The  Rectum. — The  rectum  (A  i,fig.  139),  so  called  from  its  direction,  which  is  gener- 
ally less  flexuous  than  that  of  the  rest  of  the  intestinal  canal,  is  the  last  portion  of  the 
large  intestine,  and,  consequently,  of  the  digestive  tube.  It  commences  at  the  base  of 
the  sacrum,  and  terminates  at  the  anus.  It  is  situated,  in  the  true  pelvis,  in  front  of  the 
sacrum  and  coccyx  {r,fig.  161 ;  a  o',fig.  181). 

We  see,  then,  that  the  alimentary  canal,  after  having  abandoned  the  vertebral  column 
in  order  to  describe  its  numerous  convolutions,  is  situated  at  its  termination  in  front  of 
the  lower  part  of  that  column,  just  as,  at  its  commencement,  it  is  applied  to  the  upper 
part  of  the  same.  It  is  firmly  fixed,  especially  below,  where  it.  is  surrounded  on  all  sides 
by  cellular  tissue,  and  is  also  bound  down  by  the  superior  pelvic  fascia.  This  part  of  it 
cannot,  therefore,  suffer  such  displacements  as  occur  in  hernia  ;  but,  from  its  functions 
as  an  organ  of  expulsion,  the  whole  effort  of  the  abdominal  inusoles  is  concentrated  upon 
it,  and  it  is,  therefore,  liable  to  displacements  of  a  different  kind,  viz.,  to  invagination 
and  eversion. 

Its  situation,  which  is  in  some  degree  constant,  within  a  bony  cavity,  having  unyield- 
ing walls,  and  its  relations  with  the  pelvic  fascia,  place  it  in  conditions  altogether  pecu- 
liar to  itself;  for  while  the  bladder  and  the  uterus,  which  are  also  contained  in  the  same 
cavity,  ascend  into  the  abdomen  when  they  are  distended,  the  rectum,  in  which  the  fajces 
are  accumulated,  dilates  entirely  within  the  pelvis,  and  undi^rfoes  no  change  of  position. 

From  this  fixed  condition  of  the  rectum  along  the  miildle  of  the  pelvic  cavity,  it  also 
follows  that,  in  cases  where  the  gut  is  denuded  by  destmrtion  of  the  surrounding  cellu- 
lar tissue,  it  remains  separate  from  the  walls  of  the  pelvis  :  such  is  the  nature  of  fistu- 


f 


THE   INTESTINES.  377 

lae ;  and  hence  the  necessity  of  cutting  the  rectum,  in  order  to  bring  it  in  contact  with 
the  walls  of  the  pelvis. 

Direction. — Particular  attention  should  be  paid  to  the  direction  of  this  bowel,  as  an 
anatomical  fact  from  which  practicEd  inductions  of  the  greatest  interest  may  be  derived. 
It  is  not  straight,  but  is  curved  both  in  the  antero-posterior  and  lateral  directions. 

In  the  antero-posterior  direction  it  follows  the  curve  of  the  sacrum  and  coccyx,  to  which 
it  is  closely  applied  ;  it  is,  therefore,  concave  in  front  and  convex  behind  {see  fig.  181). 
Opposite  the  apex  of  the  coccyx  it  bends  slightly  backward,  so  as  to  terminate  about  an 
inch  in  front  of  that  bone.  By  this  very  remarkable  inflection,  it  is  separated  from  the 
ragina  in  the  female,  and  from  the  urethra  in  the  male. 

T?ie  Lateral  Inclination. — On  the  left  side  of  the  base  of  the  sacrum,  and  opposite  the 
sacro-iliac  symphysis,  the  rectum  passes  downward,  and  to  the  right  side,  until  it  reaches 
the  median  line  opposite  the  third  piece  of  the  sacrum.  It  then  passes  forward,  still  in 
the  median  line,  and  forms  a  slight  curve  with  the  preceding  portion.  It  has  been  fre- 
quently said  that  the  lower  part  of  the  rectum  does  not  occupy  exactly  the  median  hne, 
but  deviates  a  little  to  the  right :  this  is  not  unfrequently  the  case  at  the  lower  part  of 
the  sacrum,  but  it  always  regains  its  original  position  before  its  termination. 

There  are,  however,  some  important  varieties  in  the  curvature  described  by  the  rec- 
tum. Thus,  it  is  not  uncommon  to  see  the  upper  part  of  the  gut  twisted  like  an  italic  <S 
before  reaching  the  median  line ;  and  in  this  case,  it  is  difficult  to  determine  whether  the 
twisted  portion  belongs  to  the  rectum  or  to  the  sigmoid  flexure  of  the  colon.  In  several 
of  the  cases  of  unnatural  position  of  the  sigmoid  flexure,  which  I  have  already  mention- 
ed, the  rectum  commenced  on  the  right  side  of  the  base  of  the  sacrum,  and  passed  down- 
ward, and  towards  the  left  side.  In  one  case,  where  the  sigmoid  flexure  was  in  its 
natural  position,  the  rectum  passed  almost  transversely  to  the  right  side,  as  far  as  the 
right  sacro-iliac  symphysis,  and  then  proceeded  very  obliquely  to  the  left  side.  The  sit- 
uation of  the  upper  part  of  the  rectum  on  the  left  of  the  median  line  has  been  often 
quoted  in  explanation  of  the  relative  frequency  of  inclinations  of  the  uterus  to  the  right 
side,  and  also  of  the  greater  or  less  amount  of  difficulty  in  parturition,  according  as  the 
occiput  of  the  foetus  is  turned  towards  the  right  or  the  left. 

Form  and  Size. — The  rectum  is  cylindrical,  not  sacculated,  and  has  no  bands  like  those 
observed  in  the  other  portions  of  the  large  intestine.  Its  external  surface  is  covered 
with  a  uniform  layer  of  well-marked,  fasciculated,  longitudinal  fibres,  which  give  it  some 
resemblance  to  the  oesophagus.  At  its  commencement,  its  caliber  is  somewhat  smaller 
than  that  of  the  sigmoid  flexure,  but  it  gradually  increases  towards  the  lower  end.  Im- 
mediately before  its  termination  at  the  contracted  orifice,  called  the  anus,  the  rectum 
presents  a  considerable  dilatation,  or  ampulla,  capable  of  acquiring  an  enormous  size  ;  so 
that,  in  certain  cases  of  retention  of  the  faeces,  it  has  been  found  occupying  the  entire 
cavity  of  the  pelvis. 

Relations. — Behind,  the  rectum  corresponds  with  the  left  sacro-iliac  sjmiphysis  and  the 
curve  of  the  sacrum  and  coccyx ;  it  is  attached  to  the  sacrum  above  by  means  of  a  fold 
of  peritoneum,  called  the  meso-rectum,  and  is  separated  from  the  sacrum  and  the  sacro- 
iliac symphysis  by  the  pyriformis  muscle,  the  sacral  plexus  of  nerves,  and  the  hypogas- 
tric vessels.  Those  portions  of  the  rectum  which  project  laterally  beyond  the  coccyx 
are  in  relation  with  the  levator  ani  muscles,  which  form  a  sort  of  floor  for  it. 

In  front,  the  rectum  is  free  in  its  upper  portion,  but  is  adherent  below ;  its  relations 
vary  in  the  two  sexes,  and  are  of  the  greatest  importance  in  a  surgical  point  of  view. 

In  the  male  its  upper  or  free  portion  {o,fig.  181)  corresponds  to  the  posterior  surface 
of  the  bladder  (A),  from  which  it  is  separated,  excepting  in  cases  of  retention  of  urine,  or 
of  considerable  dilatation  of  the  rectum  by  convolutions  of  the  small  intestines.  Its  lower 
or  adherent  portion  is  in  immediate  relation,  in  the  middle  line,  with  the  inferior  fundus 
(bas-fond)  of  the  bladder,  at  the  triangular  space  intercepted  between  the  vesicula;  semi- 
nales  (s) ;  on  each  side,  it  is  separated  from  the  bladder  by  these  vesicles.  The  extent 
to  which  it  is  in  contact  with  this  part  of  the  bladder  varies  in  different  subjects,  and  ac- 
cording as  the  bladder  and  rectum  are  full  or  empty. 

We  shall  see  in  another  place  that  the  peritoneum  {u  u)  forms  a  cul-de-sac  of  variable 
depth  between  them.  In  some  subjects  the  cul-de-sac  extends  as  far  as  the  prostate,  so 
that  the  whole  of  the  inferior  fundus  of  the  bladder  is  covered  by  it. 

In  front  of  the  inferior  fundus  of  the  bladder  the  rectum  is  intimately  united  to  the 
prostate  {i).  In  some  cases  the  prostate  projects  beyond  the  rectum,  on  one  or  both 
sides ;  in  other  cases  the  rectum  projects  beyond  the  prostate,  on  one  or  other,  or  both 
sides,  and  receives  the  gland,  as  it  were,  in  a  groove. 

The  rectum  has  also  relations  with  the  membranous  portion  of  the  urethra  (c),  but,  on 
account  of  its  inflection  backward,  it  is  separated  from  it  by  a  triangular  space,  the  base 
of  which  is  directed  downward  and  forward,  and  the  apex  upward  and  backward. 

The  practical  inferences  to  be  drawn  from  these  relations  are  these  :  that  the  bladder 
projects  into  the  rectum  in  cases  of  retention  of  urine  ;  that  the  bladder  can  be  explored 
from  the  rectum,  and  may  be  punctured  and  cut  for  the  extraction  of  stone  ;  that  the 
finger  passed  into  the  rectum  can  assist  in  the  introduction  of  the  catheter,  and  in  ex- 

Bb  B 


378  SPLANCHNOLOGY. 

amination  of  the  prostate ;  that  the  rectum  must  be  emptied  before  performing  the  lateral 
operation  for  stone  ;  and,  lastly,  that  the  membranous  portion  of  the  urethra  may  be 
opened  without  injuring  this  bowel. 

In  the  female,  the  free  portion  of  the  rectum  corresponds  with  the  broad  ligament,  the 
left  ovary  and  Fallopian  tube,  the  uterus,  and  the  vagina.  The  peritoneum  forms  a  cul- 
de-sac  between  the  vagina  and  the  rectum,  analogous  to  that  already  described  between 
the  bladder  and  the  rectum  in  the  male,  and  subject  to  the  same  varieties.  When  the 
uterus  and  the  rectum  are  empty,  a  certain  number  of  convolutions  of  the  small  intestine 
are  always  interposed  between  the  rectum  and  the  vagina ;  and,  therefore,  in  lacerations 
of  the  posterior  wall  of  the  vagina,  the  small  intestines  escape  through  the  wound. 

The  uterus  and  vagina  are  not  unfrequently  found  deviating  to  the  left  side,  while  the 
rectum  deviates  to  the  right,  and  then  the  free  portion  of  the  latter  corresponds  to  the 
right  broad  ligament  and  ovary.  Lastly,  in  retroversion  of  the  uterus,  which  is  so  com- 
mon, the  fundus  of  that  organ  rests  upon  the  rectum. 

The  inferior  or  adherent  portion  of  the  rectum  is  intimately  united  to  the  vagina  :  hence 
vaginal  cancer  frequently  extends  into  the  rectum ;  below,  on  account  of  its  inflection 
backward,  it  is  separated  from  the  vagina  in  the  same  way  as  from  the  urethra  in  the 
male,  by  a  triangular  space,  the  base  of  which  is  directed  downward,  and  forms  the 
perineum  of  the  female. 

On  the  sides,  the  free  portion  of  the  rectum  corresponds  to  the  convolutions  of  the  in- 
testines ;  the  adherent  portion  is  surrounded  by  adipose  cellular  tissue,  which  is  nowhere 
more  clearly  intended  to  fill  up  intermediate  spaces  ;  the  absorption  or  destruction  of 
this  tissue  is  an  important  circumstance  in  diseases  of  the  anus. 

The  internal  surface  of  the  rectum  is  remarkable  for  some  longitudined  folds,  which  are 
obliterated  by  distension,  and  somewhat  resemble  the  longitudinal  folds  of  the  cesophagus. 
These  folds,  which  have  been  inappropriately  termed  the  columns  of  the  rectum,  are  in- 
tersected by  other  semicircular  folds,  also  effaced  by  distension.  This  internal  surface 
presents,  moreover,  a  dilatation  corresponding  to  the  enlargement  seen  from  without, 
immediately  above  the  anus. 

Structure  of  the  Large  Intestine. — The  same  number  of  coats  exist  in  the  large  as  in  the 
small  intestine,  but  they  present  certain  peculiarities  in  arrangement,  of  which  some  are 
common  to  the  whole  bowel,  while  others  exist  only  in  particular  parts. 

The  Peritoneal  Coat. — The  peritoneum  does  not,  in  general,  form  so  complete  a  cover- 
ing for  the  large  as  for  the  small  intestine.  Moreover,  it  forms  a  great  number  of  dupli- 
catures  on  the  surface  of  the  bowel,  which  usually  contain  fat,  and  are  called  the  fatty 
appendices  {appendices  epiploica).  They  are  not  constant,  either  in  number,  size,  or 
length,  but  are  sometimes  arranged  in  regular  series.  Some  of  them  are  so  long  that 
they  may  form  the  contents  of  a  hernial  sac,  or  may  even  occasion  strsmgulation,  by 
forming  a  ring  around  the  intestines  ;'  they  are  seldom  entirely  absent.  They  become  less- 
ened when  the  gut  is  distended,  and  are  elongated  by  its  contraction.  They  are  sometimes 
loaded  with  an  immense  quantity  of  fat,  of  which  they  may  be  considered  reservoirs.  They 
are  found  along  the  whole  of  the  large  intestine,  including  the  free  portion  of  the  rectum. 

The  peritoneum  often  envelops  the  whole  of  the  caecum ;  at  other  times  it  does  not 
cover  it  behind.  Most  commonly  it  forms  a  fold,  or  mesentery,  for  the  vermiform  ap- 
pendix. It  only  passes  in  front  of  the  ascending  and  descending  colon,  which  are  al- 
ways uncovered  behind.  It  invests  the  whole  of  the  transverse  arch,  excepting  a  trian- 
gular space  behind  corresponding  to  the  transverse  mesocolon,  and  in  another  triangu- 
lar space  in  front  corresponding  to  the  great  omentum.  It  completely  surrounds  the  sig- 
moid flexure,  excepting  in  a  small  space  behind,  corresponding  to  the  iliac  mesocolon. 
Lastly,  at  the  upper  part  of  the  rectum,  it  is  arranged  in  a  similar  manner,  and  then 
merely  passes  in  front  of  that  bowel,  the  lowest  portion  of  which  is  entirely  devoid  of  a 
peritoneal  covering,  and  is  surrounded  by  a  large  quantity  of  adipose  tissue. 

From  the  arrangement  of  the  peritoneum  upon  the  large  intestine,  it  follows  that  the 
latter  is  more  favourably  circumstanced  than  the  small  intestine  for  assuming  a  large 
size ;  and,  also,  that  it  may  be  penetrated  in  many  places  without  injuring  the  peritoneum. 

The  Muscular  Coat. — As  in  the  small  intestine,  this  coat  consists  of  a  circular  and  a 
longitudinal  set  of  fibres. 

The  circular  fibres  form  the  deep  layer,  and  are  arranged  as  in  the  small  intestine  ;  the 
longitudinal  fibres,  which  constitute  the  superficial  layer,  are  not  disposed  equally  around 
the  bowel,  but  are  collected  into  three  bands,  which  we  have  already  noticed.  These 
bands  have  the  pearly  appearance  of  ligaments  when  seen  through  the  peritoneal  cover- 
ing ;*  they  are  continuous  with  the  longitudinal  fibres  of  the  appendix  vermiformis.  The 
anterior  is  the  largest ;  it  becomes  inferior  along  the  arch  of  the  colon,  and  again  ante- 
rior upon  the  descending  colon  and  sigmoid  flexure,  spreading  out  upon  the  latter.  Of 
the  posterior  bands,  which  are  narrower,  one  is  external  and  the  other  internal ;  they 
become  superior  on  the  arch  of  the  colon,  and  again  posterior  upon  the  descending  colon 
and  sigmoid  flexure,  upon  the  latter  of  which  they  are  often  blended  into  one.     I  have 

*  [They  are  involuntary  muscular  fibres  ;  in  the  lower  part  of  the  rectum  some  transversely  striated  fibres 
are  found.] 


THE   INTESTINES.  379 

already  said  that  these  bands,  being  not  more  than  one  third,  or,  at  most,  one  half  the 
length  of  the  large  intestine,  occasion  its  puckering,  and  arrangement  into  sacculi  and 
intervening  depressions. 

The  muscular  coat  is  remarkably  modified  in  the  rectum.  In  the  sigmoid  flexure  the 
longitudinal  fibres  become  scattered,  and  at  its  termination  surround  the  whole  intestine  ; 
but  this  arrangement  exists  more  particularly  in  the  rectum,  where  they  present  the  ap- 
pearance of  thick  fasciculi,  forming  an  uninterrupted  covering  (r,Jig.  161).  The  deep  or 
circular  layer  of  the  rectum  is  much  thicker  than  that  of  any  other  part  of  the  alimenta- 
ry caucil,  excepting  the  ossophagus  ;  it  may  be  separated  into  distinct  rings,  the  lowest 
of  which  is  so  distinct  that  it  has  been  described  as  a  particular  muscle,  under  the  name 
of  the  sphincter  internus.  It  is  arranged  in  precisely  the  same  way  as  the  corresponding 
coat  of  the  oesophagus,  but  is  not  so  thick :  this  difference  depends  upon  the  uses  of  the 
two  canals,  the  oesophagus  being  intended  to  convey  the  food  rapidly  downward,  while 
the  rectum  is  assisted  by  the  abdominal  muscles.  When  the  rectum  is  empty,  it  contracts 
upon  itself  like  the  oesophagus,  and  its  walls  are  in  contact. 

The  fibrous  coat  of  the  large  intestine  offers  no  peculiar  characters. 

The  mucous  coat  of  the  large  intestine  has  no  valves  :  the  semilunar  crests,  or  ridges 
which  separate  the  cells  of  the  colon,  are  formed  by  all  the  coats.  The  irregular  folds 
or  wrinkles  observed  on  this  membrane  are  completely  effaced  by  distension.  The  mu- 
cous membrane  is  not  unfrequently  protruded  through  the  muscular  fibres,  so  as  to  form 
small  sacs  having  narrow  necks,  and  containing  masses  of  indurated  faces.  At  first 
sight  such  sacs  resemble  a  varix.  They  are  very  conmion  in  the  aged,  and  are  probably 
the  result  of  habitual  constipation. 

When  examined  with  the  microscope  and  under  water,  in  the  same  manner  as  the 
mucous  membrane  of  the  small  intestine,  the  inner  surface  of  the  large  intestine  is  seen 
to  have  no  villi,  but  we  find  exactly  the  same  appearance  as  in  the  mucous  membrane 
of  the  stomach,  viz.,  an  alveolar  or  honeycomb  arrangement.*  The  openings  or  pores 
of  this  mucous  membrane  are  innumerable ;  and,  supposing  that  they  assist  both  in  ex- 
halation and  absorption,  it  may  be  conceived  with  what  rapidity  these  processes  must 
be  carried  on  in  the  large  intestine.  It  is  also  studded  with  a  number  of  follicles  (tan- 
quam  stellae  firmamenti,  Peyer),  which  are  depressed  and  perforated  in  the  centre,*  and 
in  a  great  number  of  subjects,  especially  in  the  old,  have  a  black  colour.  These  follicles 
are  never  collected  into  patches,  as  in  the  smaU  intestine,  but  are  always  solitary.  They 
are  often  inflamed,  though  the  rest  of  the  membrane  is  healthy. 

It  is  easy,  then,  to  distinguish  the  large  from  the  small  intestine,  simply  from  the  char- 
acters of  its  mucous  membrane.  The  hmit  between  the  two  is  at  the  free  margin  of  the 
ileo-caecal  valve  ;  aU  preceding  this  has  the  characters  of  the  mucous  lining  of  the  small, 
all  that  comes  after,  of  that  of  the  large  intestine. 

We  find  dense  patches  of  follicles  in  the  vermiform  appendix,  the  whole  of  which  is 
sometimes  Mned  with  them. 

The  mucous  membrane  is  more  loosely  united  to  the  fibrous  coat  in  the  rectum  than 
in  any  other  part  of  the  large  intestine.  This  looseness  is  most  marked  at  its  lower 
part,  and  hence  a  protrusion  of  this  membrane  only  may  occur,  as  in  the  oesophagus  ; 
and  this  must  be  carefully  distinguished  from  prolapsus  of  the  entire  rectum.  I  should 
also  remark,  that  the  capillary  veins  are  much  developed  at  the  lower  part  of  the  rectum, 
and,  when  much  larger  than  usual,  constitute  what  are  called  hemorrhoidal  tumours. 

Vessels  and  Nerves. — The  arteries  of  the  caecum,  the  vermiform  appendix,  the  ascend- 
ing colon,  and  the  right  half  of  the  arch,  are  supplied  by  the  superior  mesenteric ;  the 
rest  of  the  colon  and  the  rectum  receive  blood  from  the  inferior  mesenteric.  The  rec- 
tum also  receives  a  branch  from  the  internal  iliac,  called  the  middle  hemorrhoidal,  and 
a  branch  from  the  internal  pudic,  called  the  inferior  hemorrhoidal.  Some  small  ramifi- 
cations are  also  furnished  to  the  great  intestine  by  the  gastro-epiploic,  splenic,  capsular, 
and  spermatic  arteries.  The  rectum  exceeds  all  other  parts  of  the  large  intestine  in  the 
number  and  size  of  its  arteries,  and,  therefore,  operations  upon  the  lower  part  of  that 
bowel  are  often  followed  by  serious  hemorrhage. 

The  veins,  which  bear  the  same  name  and  follow  the  same  course  as  the  arteries,  concur 
in  the  formation  of  the  great  and  small  mesenteric  or  mesaraic  veins,  which  terminate 
in  the  vena  portae.  p.    jgg 

The  lympliatic  vessels  are  very  numerous,  and  terminate  in  the 

*  [In  the  stomach  this  character  is  due  to  the  presence  of  the  alveoli,  in  the  bot- 
tom of  which  the  perpendicular  tubuli  open.  In  the  large  intestine,  however, 
there  are  no  pits  ;  but  the  alveolar  appearance  is  produced  by  the  openings  of  nu- 
merous tubes,  analogous  in  form  and  direction  to  the  tubuli  of  the  stomach,  and  to 
the  crypts  of  Lieburkuhn  in  the  small  intestine. 

The  follicles  of  the  large  intestine  diifer  from  the  solitary  glands  of  the  jejunum 
and  ileum,  in  being  always  open.  Each  follicle  is  much  dilated  below,  but  has  a 
narrow  oriiice.  lu  Jig.  162,  the  upper  drawing  represents  a  vertical  section  of  a 
follicle  (magnified),  surrounded  by  the  perpendicular  tubes  ;  the  lower  is  a  magni- 
fied superficial  view,  showing  the  depression  and  opening  in  the  centre,  and  the  _=__ 
orifices  of  the  surrounding  tubes.                                                                                                              Magnified. 

The  epithelium  of  this  mucous  membrane  is  cylindrical  or  columnar.]         r-    ■■ 


380 


SPLANCHNOLOGY. 


glands  situated  along  the  attached  border  of  the  intestine  ;  the  large  intestine  is  also 
possessed  of  lacteals,  but  they  are  less  evident  than  in  the  small  intestine. 

The  nerves  are  derived  from  the  solar  plexus,  and  form  plexuses  along  the  arteries  ; 
they  all  belong  to  the  ganglionic  system.  The  rectum  alone  receives  additional  nerves 
from  the  cerebro-spinal  system,  viz.,  from  the  hypogastric  and  sacral  plexuses.  The 
presence  of  these  two  sets  of  nerves  has  reference  to  the  functions  of  the  bowel,  which 
are  partly  involuntary  and  partly  subject  to  the  influence  of  the  will. 

The  Anus. — The  word  anus,  borrowed  from  the  Latin,  signifies  the  lower  orifice  of  the 
alimentary  canal  (the  anal  orifice) ;  it  is  a  narrow  but  dilatable  opening,  through  which 
the  faeces  are  expelled. 

It  is  situated  in  the  median  line,  about  an  inch  in  front  of  the  point  of  the  coccyx,  at 
the  back  part  of  the  perineum,  between  the  tuberosities  of  the  ischium,  and  at  the  bot- 
tom of  the  fissure  between  the  buttocks.  The  skin  around  the  borders  of  this  orifice, 
wfiich  is  constantly  closed,  contains  a  great  number  of  sebaceous  follicles,  and  is  cover- 
ed with  hair  in  the  male  ;  it  passes  deeply  into  the  orifice,  to  become  continuous  with 
the  mucous  membrane,  and  presents  a  great  number  of  radiated  folds,  which  are  effaced 
during  dilatation.  The  point  at  which  it  becomes  continuous  with  the  mucous  mem- 
brane is  deserving  of  notice  :  it  is  within  the  rectum,  at  the  distance  of  some  lines  from 
the  anus  properly  so  called,  and  is  marked  by  a  waved  line,  which  forms  a  series  of 
arches  or  festoons,  having  their  concavities  directed  upward.  Sometimes  there  are 
small  pouches  in  the  situation  of  these  arches,  opening  upward.  From  the  angles  at 
which  the  arches  unite,  some  mucous  folds  proceed,  and  small  foreign  bodies,  detached 
from  the  faeces,  are  often  retained  in  the  culs-de-sac,  and  become  the  causes  of  fistulae. 

Structure  of  the  Anus. — The  anus,  intended  as  it  is  to  prevent  the  revolting  inconve- 
nience of  a  constant  and  involuntary  escape  of  the  faeces,  consists  essentially  of  a  sphinc- 
ter muscle,  which  is  antagonized,  not  only  by  the  proper  dilator,  viz.,  the  levator  ani,  with 
which  I  connect  the  ischio-coccygeus,  but  also  by  the  diaphragm  and  the  abdominal  mus- 
cles. The  absence  of  a  sphincter  is  the  great  evil  of  every  artificial  anus.  A  fourth 
muscle,  the  transversalis  perinei,  must  also  be  included  among  the  muscles  of  the  anus. 

The  skin  and  the  mucous  membrane  which  cover  these  muscles  are  remarkable  for  the 
great  development  of  the  erectile  tissue,  which  forms  the  basis  of  all  tegumentary  mem- 
branes. The  terminal  branches  of  the  hemorrhoidal  arteries  are  extended  upon  this 
portion  of  the  skin  and  mucous  membrane.  From  this  erectile,  and,  therefore,  vascular 
tissue,  arise  a  great  number  of  winding,  twisted,  and  plexiform  veins,  which  form  the 
lowest  roots  of  the  vena  portae.  A  considerable  number  of  cerebro-spinal  and  ganglionic 
nerves,  derived  from  the  sacral  plexus  and  the  hypogastric  nervous  centre,  are  distribu- 
ted around  this  orifice.  Lastly,  there  are  mucous  crypts,  or,  rather,  glands,  a  vestige 
of  the  highly-developed  glandular  organ  found  in  some  animals. 

Muscles  of  the  Anus. — We  now  proceed  to  the  description  of  the  muscles  of  the  anus, 
which  are  six  in  number,  viz.,  two  single  muscles,  the  sphincter  and  the  transversalis  pe- 
rinei ;  and  two  pairs,  the  levatores  ani  and  the  ischio-coccygei,  which,  in  fact,  form  but 
one  muscle.  The  sphincter  intcmus  of  authors  is  nothing  more  than  the  last  ring  of  the 
circular  fibres  of  the  rectiun. 

The  Sphincter  Ani. 
Dissection. — Remove  carefully  the  corrugated  skin  which  covers  the  anal  region ;  pro- 
long the  dissection  backward  as  far  as  the  coccyx,  and  forward  to  the  scrotum  in  the 
male,  and  the  vulva  in  the  female.  It  is  not  sufficient  to  expose  the  lower  ring  of  the 
sphincter  ;  the  adipose  tissue,  which  surrounds  the  lower  part  of  the  rectum,  should  be 
removed  on  each  side.  It  is  well  to  stuff  the  lower  part  of  the  rectum  preparatory  to 
this  dissection,  as  well  as  that  of  the  muscles  of  the  perineum. 

The  sphincter  ani  {a,  fig.  163)  is  an  orbicular  muscle,  situated  around  the  lower  end  of 
j^^.  163.  the  rectum.     It  is  not  a  simple  ring,  but 

a  muscular  zone  of  nearly  an  inch  in 
width.  Its  form  is  an  ellipse,  much  elon- 
gated from  before  backward,  and  tenni- 
nating  in  a  point  in  front  and  behind. 
The  fibres  which  constitute  the  lower- 
most ring  of  the  muscle  arise  from  the 
sub-cutaneous  cellular  tissue  in  front  of 
the  coccyx,  in  the  same  manner  as  other 
cutaneous  muscles ;  those  which  fonn 
the  upper  rings  arise  from  a  sort  of 
fibrous  tissue  given  off  from  the  point 
of  the  coccyx.  From  these  points  the 
fleshy  fibres  proceed  forward,  and  fonn 
a  semi-ellipse  on  each  side,  composed 
of  pa'rllel  and  superimposed  muscular 
rings,  which  terminate  in  front  of  the  anus  in  the  folldwing  manner :  The  lower  rings 


THE    INTESTINES.  381 

in  the  sub-cutaneous  cellular  tissue,  the  upper  rings  in  the  sort  of  fibrous  raph^,  which 
gives  origin  to  the  bulbo-cavemosus. 

Relations. — The  internal  surface  of  the  sphincter  embraces  the  lower  part  of  the  rec- 
tum, the  lowest  circular  fibres  of  which  are  seen  within  the  sphincter,  and  are  distin- 
guished from  it  by  their  paleness.  They  constitute  the  internal  sphincter.  Its  external 
surface  is  in  relation  with  the  adipose  tissue  of  the  pelvis.  Its  upper  border  is  continu- 
ous with  the  antero-posterior  fibres  of  the  levaotr  ani ;  so  that  it  is  very  difficult  to  es- 
tablish the  limit  between  them. 

Its  inferior  border  projects  a  little  below  the  lowest  annular  fibres  of  the  rectum,  and 
only  adheres  to  the  skin  by  loose  cellular  tissue,  which  is  continuous  with  the  dartos. 

Action. — It  is  a  constrictor  of  the  anus.  The  contraction  of  the  body  of  the  muscle 
closes  the  lower  part  of  the  rectum ;  the  constriction  produced  by  the  inferior  ring  oc- 
curs below  that  bowel. 

The  Transversus  Perinei. 

Dissection. — Remove  with  care  the  sub-cutaneous  cellular  tissue  in  front  and  upon  the 
sides  of  the  anus. 

The  transversus  perinei  (b)  is  situated  almost  transversely  in  front  of  the  anus.  It 
arises  from  the  internal  lip  of  the  tuberosity  of  the  ischium,  immediately  above  the  ischio- 
cavemosus  {erector  penis),  by  a  broad  and  thin  tendon,  which  is  soon  succeeded  by  fleshy 
fibres.  These  pass  inward  and  a  little  forward,  on  to  the  anterior  surface  of  the  rectum, 
where  they  are  usually  described  as  becoming  blended  with  those  of  the  opposite  side 
in  a  fibrous  raphe,  common  both  to  the  transversi,  the  sphincter,  and  the  bulbo-cavernosi 
{acceleratores  urinoe).  This  does  not  appear  to  me  to  be  the  exact  termination.  I  have 
seen  this  muscle  evidently  continuous  with  that  of  the  opposite  side,  after  having  trav- 
ersed the  anterior  extremity  of  the  sphincter.  According  to  this,  the  two  transversi 
would  constitute  a  single  muscle,  forming  a  half  ring,  the  concavity  of  which,  being  di- 
rected backward,  would  embrace  the  anterior  part  of  the  rectum,  an  arrangement  well 
calculated  to  assist  in  expulsion  of  the  faeces. 

Relations. — This  muscle  is  placed  at  the  boundary  between  the  anal  and  perineal  re- 
gions. It  forms  the  posterior  side  of  a  triangle,  of  which  the  outer  side  is  formed  by 
the  ischio-cavernosus  (c),  and  the  inner  by  the  bulbo-cavemosus  (d).  It  is  sub-cutaneous, 
excepting  in  the  median  line,  and  is  in  relation  above  with  the  levator  ani. 

Action. — It  tends  to  compress  and  force  the  anterior  against  the  posterior  surface  of 
the  rectum,  which  we  shall  see  is  pushed  forward  by  the  levator  ani.  It  therefore  as- 
sists powerfully  in  defsDcation. 

The  Ischio-coccygeus  and  Levator  Ani 

Dissection. — These  muscles  must  be  studied  both  from  the  perineum  and  from  the  in- 
terior of  the  pelvis.  In  the  perineum  :  remove  the  adipose  tissue,  which  occupies  the 
interval  between  the  rectum  and  the  obturator  internus  ;  in  order  to  expose  the  whole 
of  the  ischio-coccygeus,  cut  the  lower  edge  of  the  glutaeus  maximus,  and  carefully  divide 
the  great  and  small  sacro-sciatic  ligaments.  In  the  pelvis :  remove  the  peritoneum  li- 
ning the  sides  of  that  cavity ;  remove  the  superior  pelvic  fascia  which  covers  these  mus- 
cles, and  trace  them  very  carefully  backward  and  upon  the  sides  of  the  rectum,  the  blad- 
der, and  the  prostate  gland. 

The  ischio-coccygeus  and  the  levator  ani  constitute  the  floor  of  the  pelvis.  They  form 
an  uninterrupted  muscular  plane,  from  the  lower  border  of  the  pyriformis  muscle  to  the 
arch  of  the  pubes.  The  ischio-coccygeus  includes  that  portion  which  is  inserted  into  the 
sides  of  the  coccyx:  the  remainder  is  the  levator  ani. 

The  Ischio-coccygeus,  or  Coccygeus. 

This  is  a  flat,  triangular,  or,  rather,  a  radiated  muscle  (o),  situated  at  the  lower  part 
of  the  pelvis,  in  front  of  the  sacro-sciatic  ligaments.  It  arises  from  the  sides  and  sum- 
mit of  the  spine  of  the  ischium,  from  the  anterior  surface  of  the  lesser  sacro-sciatic  lig- 
ament, and  often  from  the  posterior  part  of  the  pelvic  feiscia ;  it  passes  in  a  radiated 
manner  to  the  border  of  the  coccyx  and  the  lower  part  of  the  border  of  the  sacrum.  All 
these  attachments  are  eflfected  by  aponeurotic  fibres,  to  which  the  fleshy  fibres  succeed. 
In  this  respect  its  structure  has  considerable  analogy  with  that  of  the  intercostal  mus- 
cles, the  tendinous  portion  exceeding  the  muscular. 

Relations. — Its  upper  surface  {o,fig.  Ill)  is  slightly  concave,  and  corresponds  to  the 
rectum  ;  its  Zoicer  surface  {fig.  163)  is  slightly  convex,  and  is  in  relation  with  the  sacro- 
sciatic  ligaments  and  the  glutaeus  maximus ;  its  posterior  margin  is  applied  to  the  lower 
border  of  the  pyriformis  ;  its  anterior  margin  is  continuous,  without  any  line  of  demar 
cation,  with  the  posterior  margin  of  the  levator  ani  (n),  from  which  muscle  it  can  be  dis- 
tinguished merely  by  its  tendinous  structure. 

Action. — It  assists  in  forming  the  floor  of  the  pelvis.  It  tends  to  draw  the  coccyx  to 
its  own  side  :  when  the  muscles  of  both  sides  act  together,  the  coccyx  is  fixed,  and  can- 
not be  thrown  backward.  It  acts,  therefore,  in  defalcation.  The  name  levator  coccygis, 
which  was  given  to  it  by  Morgagni,  is  altogether  inapolicable. 


SS2  SPLANCHNOLOGY. 

The  Levator  Ani.  '    "''*•' 

This  muscle  («),  so  called  from  one  of  its  chief  uses,  is  situated  in  the  cavity  of  the 
pelvis,  and  with  its  fellow  forms  a  sort  of  muscular  floor,  which,  in  many  respects,  re- 
sembles that  formed  by  the  diaphragm.  It  is  thin,  curved,  and  quadrilateral,  narrow  in 
front,  and  broad  behind. 

It  arises,  by  its  fixed  or  upper  attachments,  in  front,  from  the  pubis,  at  the  side  of,  and 
sometimes  even  from  the  symphysis  ;  behind,  from  the  anterior  border  of  the  spine  of  the 
ischium,  and  in  the  interval  between  these  extreme  points  from  the  upper  part  of  the  ob- 
turator foramen,  and  from  the  brim  of  the  pelvis. 

Its  movable  attachments  are  to  the  side  of  the  prostate,  the  bladder,  and  the  rectum,  to 
the  point  of  the  coccyx,  and  to  the  fibrous  raphe  extending  from  that  point  to  the  sphinc- 
ter. The  fibres  arising  from  the  symphysis  pubis  are  concealed  by  the  pubio-prostatic 
ligament  ;*  they  are  few  in  number,  short,  and  directed  inward,  backward,  and  down- 
ward, to  form  a  bundle  (the  prostatic),  which  was  described  by  Santorini  as  the  levator 
prostatcB,  and  by  Winslow  as  le  prostatique  supirieur.  The  fibres  arising  from  the  spine 
of  the  ischium  are  blended  at  their  origin  with  those  of  the  coccygeus,  and  pass  trans- 
versely inward  to  the  point  of  the  coccyx.  The  origins  from  the  upper  pai-t  of  the  obtu- 
rator foramen  and  from  the  brim  of  the  pelvis  take  place  by  means  of  the  pelvic  apo- 
neurosis, which  divides  and  receives  the  muscle  between  its  two  layers  (i.  e.,  the  supe- 
rior pelvic  and  the  obturator  fasciae).  These  fibres,  the  hindermost  of  which  are  the 
longest,  all  pass  inward,  describe  a  curve  having  its  concavity  directed  upward,  and  are 
divided  into  the  vesical,  anal,  and  pnz-coccygeal.  The  vesical  fibres  pass  upon  the  sides 
of  the  inferior  fundus  (bos-fond)  of  the  bladder.  I  have  never  seen  them  terminate  on 
the  vesiculae  seminales.  The  anal  fibres  having  reached  the  sides  of  the  rectum,  above 
the  sphincter,  pass  backward,  and  meet  behind  the  bowel.  They  constitute  a  half  ring 
on  each  side,  prolonging  the  sphincter  upward,  without  any  distinct  line  of  demarcation. 
The  pra-coccygeal  fibres  are  directed  backward,  and  form  a  thick  fleshy  layer,  occupying 
the  interval  between  the  coccyx  and  the  sphincter,  and  completing  the  lower  wall  or  floor 
of  the  pelvis.    In  the  female  there  are  also  vaginal  fibres. 

Relations. — Its  upper  or  internal  surface  is  covered  by  the  superior  pelvic  fascia,  which 
separates  it  from  the  peritoneum  and  the  organs  contained  in  the  pelvis.  The  obturator 
fascia  intervenes  between  its  lower  or  external  surface  and  the  internal  obturator  mus- 
cle, from  which  it  is  separated  below  by  a  large  triangular  space,  narrow  above  and  broad 
below,  and  filled  with  adipose  tissue.     Its  posterior  part  is  in  relation  with  the  glutaeus. 

Action. — It  serves  as  a  muscular  floor  for  the  pelvis.  It  raises  the  prostate,  the  infe- 
rior fundus  of  the  bladder  and  the  anus,  and  counteracts  the  effect  of  the  diaphragm  and 
abdominal  muscles  during  violent  exertions.  It  assists  powerfully  in  the  expulsion  of 
the  urine,  the  seminal  fluid,  and  the  faeces. 

As  the  largest  portion  of  the  muscle  occupies  the  sides  and  the  back  of  the  rectum,  its 
especial  use  is  to  expel  the  contents  of  that  bowel :  this  is  effected  by  the  pree-coccygeal 
fibres  of  both  muscles  elevating  the  rectum,  and  by  their  anal  fibres  drawing  it  forward 
and  upward,  and  compressing  it  on  the  sides. 

Functions  of  the  Large  Intestine. — In  the  large  intestine,  the  alimentary  substances  ac- 
quire the  odour  and  all  the  other  characters  of  the  faeces  ;  any  remaining  nutritious  mat- 
ter or  chyle  which  they  may  contain  is  absorbed,  and  they  become  hardened  and  mould- 
ed in  the  cells  of  the  colon.  Absorption  is  sufficiently  active  in  the  large  intestine  to 
enable  life  to  be  supported  for  a  considerable  period  by  means  of  nutritive  enemata,  in 
persons  who  cannot  receive  food  into  the  stomach.  The  large  intestine  acts  also  as  a 
reservoir  ;  its  long  course,  its  curvatures,  and  its  easily  yielding  character,  enable  it  to 
contain  a  great  quantity  of  matter,  and  prevent  the  inconvenience  of  constant  defaecation. 

The  appendix  vermiformis  has  no  use  in  man  ;  it  is  merely  the  trace  of  a  largely-de- 
veloped intestine  in  herbivorous  animals. 

The  rectum  is  the  final  reservoir,  and  one  of  the  agents  in  the  expulsion  of  the  faeces, 
the  presence  of  which  gives  rise  to  a  sensation  that  informs  us  of  the  necessity  for  evac- 
uating them.  The  sphincter,  in  general,  opposes  this  evacuation,  until  it  is  determined 
upon  by  the  will.  The  expulsion  is  effected  by  the  action  of  the  rectum,  assisted  by  the 
diaphragm  and  the  abdominal  muscles. 

Development  of  the  Intestinal  Canal. 

The  development  of  the  intestinal  canal  offers  two  subjects  for  consideration,  viz.,  the 
relations  existing  between  it  and  that  portion  of  the  foetal  membranes  called  the  vesicula 
umbilicalis;  and  the  development  of  the  canal  itself,  independently  of  that  vesicle. 

In  reference  to  the  first  point,  the  anatomy  of  the  human  foetus  is  still  involved  in  much 
obscurity,  authorities  being  divided  in  opinion  on  the  subject.  Without  entering  here 
into  a  discussion  which  belongs  to  a  higher  department  of  anatomy,  I  would  observe,  that 

*  [/.  e.,  by  the  anterior  folds  of  the  Teeto-vesical  fascia,  from  which  the  fibres  in  question  partly  arise,  and 
by  which  they  are  separated  from  the  levator  ani  :  the  posterior  layer  of  the  triangular  ligament  is  in  relation 
■with  them  in  front.] 


THE    INTESTINES. 

the  principal  arguments  adduced  by  those  who  admit  the  communication  between  the 
intestinal  canal  and  the  vesicula  umbilicalis  are  drawn  from  analogy,  and  especially  from 
what  occurs  in  oviparous  animals,  whose  viteUine  membrane  is  regarded  as  analogous 
to  the  umbihcal  vesicle,  and  in  which  the  most  evident  communication  exists  at  all  sta- 
ges of  foetal  existence. 

I  would  observe,  also,  that  these  same  anatomists  are  not  agreed  respecting  the  point 
at  which  this  communication  occurs.  According  to  Oken,  it  is  at  the  junction  of  the 
small  with  the  large  intestine  :*  according  to  Meckel,  it  is  at  the  lower  part  of  the  small 
intestine,  and  the  diverticula  so  frequently  observed  in  this  place  are  vestiges  of  the  ca- 
nal of  communication.  The  last-named  anatomist,  after  having  discussed  all  the  argu- 
ments on  either  side  of  the  question,  concludes  thus :  "I  think,  then,  that  we  must  at 
present  admit  a  continuity  of  substance  between  the  umbilical  vesicle  and  the  intestinal 
canal,  without  pretending  to  decide  whether  the  cavities  of  these  two  organs  open  into 
each  other"  {Manual  d'Anatomie,  torn,  iii.,  p.  416,  trad,  par  MM.  jourdan  et  Breschet; 
But  the  communication  of  the  cavities  is  evidently  the  entire  question. 

The  arguments  of  those  who  deny  the  existence  of  a  communication  in  the  human  foetus 
and  mammalia  are  founded  upon  direct  observation.  I  must  say,  with  Emmert,  Cuvier, 
and  others,  that  I  have  never  detected  this  communication  ;  and  though  I  am  far  from 
denying  it  altogether,  yet  I  consider  that  facts  are  still  wanting  to  prove  its  existence.! 

The  development  of  the  intestinal  canal  itself  presents,  besides  some  questions  yet  un- 
determined, certain  positive  facts,  concerning  which  there  can  be  no  dispute.  One  of 
the  undetermined  questions  relates  to  the  mode  in  which  the  intestine  is  formed.  Is  the 
digestive  tube  originally  an  oblong  vesicle,  which  becomes  elongated,  at  the  same  time, 
at  both  its  cephaUc  and  its  coccygeal  extremities,  both  being  at  first  imperforate,  but  af- 
terward opening  so  as  to  form  the  mouth  and  anus  ]  Does  it  at  first  resemble  a  groove 
open  in  front,  as  Wolf  has  shown  to  be  the  case  in  birds  ;  or  is  it  developed  from  two 
lateral  halves,  subsequently  united  together,  according  to  the  opinion  of  M.  SerresT  Is 
the  intestinal  caned  formed  from  one,  or  from  several  centres  of  development  1  Is  it  de- 
veloped from  several  pieces,  which  afterward  meet  each  other,  so  to  speak  1  and  are  any 
grounds  for  this  opinion  afforded  by  the  absence  of  different  portions  of  the  canal  in 
acephalous  monsters,  or  the  occasional  existence  of  septa  in  different  parts  of  its  extent  ] 
I  think  not. 

Upon  the  whole,  these  microscopical  investigations  into  the  first  traces  of  the  devel- 
opment of  organs  are  still  involved  in  great  obscurity  ;  and  I  must  say  that,  whenever  I 
have  been  able  to  discern  the  intestinal  canal,  it  has  appeared  to  me  to  form  a  complete 
cylinder,  t  Another  question,  which  yet  remains  undetermined,  relates  to  the  situation 
of  the  intestine  in  the  early  periods  of  intra-uterine  existence.  It  is  at  first  situated,  as 
some  authors  believe,  in  front  of  the  vertebral  column ;  or,  rather,  as  others  imagine,  in 
that  portion  of  the  cord  which  is  next  the  umbilicus. 

Embryologists  agree  in  stating  that,  in  the  earliest  periods  of  its  development,  the  in- 
testinal canal  is  not  contained  in  the  abdominal  cavity,  but  only  its  two  extremities  ;  all 
the  intermediate  part,  i.  e.,  almost  the  whole  of  the  canal,  is  situated  within  the  umbili- 
cal cord,  which  at  that  time  is  very  considerably  enlarged.  The  whole  intestinal  canal  is 
not  included  in  the  cavity  of  the  abdomen  until  towards  the  middle  of  the  third  month. 

This  fact  is  quoted  in  explanation  of  congenital  umbilical  hernia,  which  would  be  con- 
sidered merely  an  arrest  of  development.  I  must  here  remark,  that  this  situation  of  the 
intestines,  in  a  cavity  formed  within  the  umbiUcal  cord,  does  not  seem  to  me  to  have 
been  clearly  established ;  that  there  are  a  great  number  of  cases  where  no  such  arrange- 
ment exists  ;  that  in  other  cases  there  is  only  a  loop  of  the  intestine  in  the  substance  of 
the  cord ;  and,  lastly,  that  the  cases  in  which  such  an  arrangement  has  been  observed, 
if  not  examples  of  actual  disease,  may  at  least  be  regarded  as  instances  in  which  the  de- 
velopment of  the  anterior  wall  of  the  abdomen  had  been  retarded.<J 

Dimensions  of  the  Intestinal  Canal. — The  earlier  the  period  of  development,  the  shorter 
and  narrower  is  the  intestinal  canal.  Its  length  at  first  appears  to  correspond  to  that  of 
the  vertebral  column,  a  relation  which  is  natural  and  permanent  in  a  great  number  of  the 
lower  animals.  The  canal  soon  becomes  flexuous,  and  its  windings  become  more  nu- 
merous in  proportion  as  it  increases  in  length.  From  the  third  to  the  fourth  month,  its 
curves  are  analogous  to  those  which  it  subsequently  describes  :  at  the  sixth  month,  the 
due  proportion  between  the  different  parts  of  the  canal  is  established.  At  the  earlier 
periods,  the  small  intestine  has  a  much  greater  caliber  in  proportion  to  the  large  intes- 
tine than  it  afterward  presents ;  and,  on  the  other  hand,  the  large  intestine  is  relatively 
longer  than  at  subsequent  periods. 

The  division  into  the  large  and  the  small  intestines  does  not  exist  at  first.     There  is 

*  The  Termiform  appendix  and  the  caecum  are  the  remains  of  this  communication,  according  to  Oken. 

t  [The  communication  has  been  distinctly  seen  and  described  by  Dr.  Allen  Thomson. — (Edin.  Med.  and 
Surg.  Journ.,  cxl.,  p.  132.)] 

}  [In  the  ovum,  No.  II.,  described  by  Dr.  A.  Thomson  {loc.  cit.),  the  future  alimentary  canal  has  the  forn 
of  a  groove.] 

If  [The  presence  of  a  portion  of  the  intestinal  canal  within  the  umbilical  cord,  at  some  period  of  development 
is  constant  not  only  in  man,  but  in  several  quadrupeds,  and  cannot  be  merely  accidental.] 


SPLANCHNOLOGY. 

no  ileo-caecal  valve,  no  caecum,  and  no  appendix  vermiformis  ;  but  these  three  means  of 
distinction  appear  simultaneously  from  the  second  to  the  third  month.*  The  caecum  and 
the  vermiform  appendix  are  not  distinct  from  each  other,  but  present  the  appearance  of 
a  sort  of  funnel.  The  appendix,  though  at  first  small,  is  gradually  developed,  and  be- 
comes proportionally  greater  than  it  is  afterward ;  its  caliber  is  nearly  one  half  that  of 
the  small  intestine.  If  it  be  not  quite  correct  to  say,  with  Hallcr,  that  the  caecum  does 
not  exist  in  the  foetus,  yet  it  must  be  admitted  that,  at  this  period  of  existence,  it  is  no- 
thing more  than  the  expanded  base  of  the  vermiform  appendix  ;  and  the  development 
which  it  acquires  after  birth  may,  to  a  certain  degree,  be  regarded  as  the  mechanical  ef 
feet  of  the  weight  of  the  faecal  matters  in  dilating  its  cells.  The  anterior  cells  of  the 
ceecum,  on  account  of  its  vertical  position,  undergo  a  relatively  greater  amount  of  dilata- 
tion ;  and  from  this  the  vermiform  appendix,  which  corresponded  at  first  to  the  centre 
of  the  lower  end  of  the  caecum,  is  turned  backward,  inward,  and  to  the  left  side,  towards 
the  ileum.  The  caecum  and  the  appendix  do  not  occupy  the  right  iliac  fossa  until  the 
fourth  or  fifth  month ;  before  that  time  they  are  situated  in  the  neighbourhood  of  the  um- 
bilicus. For  the  first  four  or  five  months  of  intra-uterine  life,  the  large  intestine  is  not 
sacculated  ;  so  that  its  external  surface  is  exactly  similar  to  that  of  the  small  intestine, 
the  only  means  of  distinguishing  one  from  the  other  being  the  situation  of  the  vermiform 
appendix.  About  the  fifth  month,  according  to  Morgagni,  the  three  longitudinal  depres- 
sions, and  the  transverse  folds  or  depressions  and  intermediate  protuberances,  make 
their  appearance  simultaneously.  These  characters  are  first  observed  in  the  transverse 
arch  of  the  colon. 

The  valvulae  conniventes  of  the  small  intestine  do  not  appear  until  about  the  seventh 
month,  and  they  are  very  slightly  developed  at  birth.  It  is  not  uninteresting  to  remark, 
that  the  condition  of  the  foetus,  in  this  respect,  resembles  that  of  animals,  which  never 
have  valvulae  conniventes.  The  villi,  however,  can  be  observed  as  early  as  the  third 
month.  Meckel  considers  that  they  are  developed  from  folds  of  the  mucous  membrane, 
the  surfaces  of  which  become  notched.  At  the  same  period,  according  to  that  author, 
villi  are  very  apparent  in  the  large  intestine  ;  but,  after  the  seventh  month,  they  diminish 
in  number  and  size,  while  those  of  the  small  intestine  remain,  even  if  they  do  not  increase. 

At  first  it  is  impossible  to  distinguish  the  several  coats  of  the  intestine  ;  the  serous  and 
the  mucous  membrane  can  alone  be  recognised.     The  intestine  is  perfectly  transparent. 

The  great  omentum  first  appears  during  the  third  month,  along  the  convex  edge  of  the 
stomach,  like  a  small  and  very  thin  border.  Fat  is  never  found  within  it  before  birth  ; 
nor  are  the  appendices  epiploicae  developed  until  after  that  event. 

At  birth,  the  intestinal  canal  presents  the  same  characters  as  it  afterward  possesses. 
The  small  intestine  is  already  provided  with  rudimentary  valvulae  conniventes,  with  well- 
marked  villi,  and  with  very  evident  solitary  and  agminated  glands.  The  large  intestine, 
which  is  much  developed,  is  distended  with  meconium ;  the  caecum  is  shorter  than  it 
afterward  becomes,  the  vermiform  appendix  is  larger,  and  the  ileo-caecal  valve  has  the 
same  appearance  as  in  the  adult.  The  mucous  membrane  of  the  large  intestine  is  al- 
ready characterized  by  its  solitary  follicles  and  alveolar  appearance. 

In  the  large  intestine  of  the  foetus,  we  find,  instead  of  faecal  matter,  a  thick,  viscid  in- 
odorous, and  dark-green  substance,  which  fills  the  bowel  more  or  less  completely.  This 
is  the  meconium,  so  called  from  the  Greek  word  /i^kuv,  a  poppy,  because  it  bears  some 
resemblance  in  colour  and  consistence  to  the  juice  of  that  plant.  Its  quantity  increases 
towards  the  period  of  birth.  The  time  at  which  it  first  appears  has  not  been  ascertained  : 
I  have  found  it  in  foetuses  of  four  or  four  and  a  half  months,  but  then  it  only  occupied  the 
rectum.  From  the  seventh  to  the  ninth  month  it  is  accumulated  in  the  sigmoid  flexure, 
and  diminishes  in  quantity  towards  the  ileo-caecal  valve.  The  vermiform  appendix  is 
not  unfrequently  found  distended  with  this  matter.  The  small  intestine  also  contains 
a  mucous  substance  ;  but  it  is  less  abundant  and  less  viscid,  sometimes  colourless,  and 
sometimes  yellowish  or  greenish. 

The  changes  which  take  place  in  the  intestinal  canal  after  birth,  affecting  its  caliber, 
its  situation,  and  its  length,  appear  to  me  to  depend  upon  its  being  more  or  less  distended 
with  gas  and  faecal  matters,  and  on  its  being  displaced  in  consequence  of  adhesions,  in- 
crease of  size,  or  displacement  of  other  organs.  I  have  proved  that  in  females  who  have 
had  children,  the  intestines  present  more  varieties  in  situation  than  in  males.  We  may 
add,  that  these  differences  in  position  are  much  more  frequently  observed  in  the  large 
than  in  the  small  intestine. 


APPENDAGES  OF  THE  ALIMENTARY  CANAL. 
The  Liver  and  its  Excretory  Apparatus. — The  Pancreas. — The  Spleen. 
The  appendages  of  the  sub-diaphragmatic  portion  of  the  alimentary  canal  are  the  liver 
and  pancreas,  two  glandular  organs  which  pour  their  secretions  into  the  duodenum,  and 
the  spleen,  which  may  be  regarded  as  an  appendage  of  the  liver. 

*  Haller,  who,  in  this  and  many  other  passages,  seems  to  have  foreseen  the  law  of  unity  of  organization, 
says,  "  Eadem  primordialis  hominis  fere  fabrica  est  quae  quadrupedum." — (Lib.  xxiv.,  D.  116.) 


.     THE    LIVER. 

•»i>j'>  -A  ■   ■  .   .  The  Livee. 

The  liver  {I  I',  figs.  155,  161)  is  a  glandular  organ,  intended  for  the  secretion  of  bile. 
Moreover,  it  is  to  this  organ  that  the  blood  of  the  abdominal  venous  system  is  carried  in 
the  adult,  and  that  of  two  systems  of  veins  in  the  foetus. 

It  is  situated  near  the  duodenum,  i.  e.,  the  portion  of  the  intestinal  canal  into  which  the 
bile  is  poured ;  it  occupies  the  whole  of  the  right  hjT)ochondrium,  advances  into  the  epi- 
gastrium, and  even  slightly  into  the  left  hypochondrium.  It  is  protected  by  the  seven  or 
eight  lower  ribs  on  the  right  side,  which  defend  it  from  external  violence  ;  and  it  is  separ- 
ated from  the  thoracic  organs  by  the  diaphragm.  It  is  supported  by  folds  of  the  peri- 
toneum connecting  it  with  the  diaphragm,  and  regarded  as  suspensory  ligaments ;  by 
the  stomach  and  intestines,  which  form  a  sort  of  elastic  cushion  for  it ;  and  by  the  vena 
cava,  which  is  intimately  adherent  to  it.  These  me^ns  of  support  and  attachment  allow 
of  slight  movements  to  and  fro,  and  even  of  certain  changes  of  position,  not  amounting 
to  displacement.  Thus,  it  is  depressed  during  inspiration,  and  projects  a  little  below  the 
edges  of  the  costdi  cartilages  ;  it  is  raised  during  expiration  ;  it  sinks  slightly  downward 
during  the  erect  posture,  and  backward,  or  in  the  direction  in  which  its  own  weight 
would  drag  it,  according  to  the  way  in  which  the  body  lies  during  the  horizontal  posi- 
tion ;  it  is  pushed  upward  by  tumours  in  the  abdomen,  and  dovraward  by  effusions  in  the 
chest.  The  disturbed  sleep  to  which  many  individuals  are  subject  when  lying  upon  the 
left  side,  is  attributed  to  the  pressure  of  the  liver  upon  the  stomach  ;  and  to  the  dragging 
of  the  liver  upon  the  diaphragm  has  been  eiscribed  the  sensation  of  hunger,  as  well  as 
the  relief  of  that  feeling  produced  by  tying  something  tight  around  the  abdomen.  These 
notions  are,  however,  purely  hypothetical ;  and  generally,  in  solving  such  questions,  the 
exact  state  of  fulness  of  the  abdomen,  and  of  the  mutual  action  and  reaction  of  the  ab- 
dominal parietes  and  viscera,  has  not  been  sufficiently  taken  into  account.  True  dis- 
Dlacements  of  the  liver  are  very  rare,  and  hepatocele  (hernia  of  the  liver)  is  the  result  of 
an  imperfect  development  of  the  walls  of  the  abdomen. 

Size. — The  liver  is  the  largest  and  heaviest  of  all  the  organs  of  the  body ;  and,  indeed, 
in  the  human  subject,  it  exceeds  in  weight  and  in  size  all  the  other  glands  together.  It 
is  not  true,  as  the  ancients  declared,  that  the  liver  is  larger  in  man  than  in  any  other 
animal.  But  the  opinion  maintained  by  many  naturalists,  that  there  is,  in  the  animal 
series,  an  inverse  ratio  between  the  size  of  the  liver  and  the  development  of  the  respira- 
tory organs,  so  that  this  organ  is  much  larger  in  reptiles  and  fishes,  whose  respiration  is 
slight,  than  in  birds  and  mammalia,  which  respire  vigorously,  is  not  altogether  devoid  of 
loundation. 

The  liver  weighs  from  three  to  four  pounds,  thus  forming  one  thirty-sixth  of  the  whole 
weight  of  the  body  according  to  Bartholin,  and  one  twenty-fifth  according  to  others.  Its 
longest  diameter,  the  transverse,  is  from  ten  to  twelve  inches  ;  its  antero-posterior  di- 
ameter is  from  six  to  seven  inches  ;  and  its  vertical  diameter  in  the  thickest  part,  from 
four  to  five.  These  dimensions  are  extremely  variable,  but  are  always  inversely  pro- 
portional to  each  other.  In  a  great  many  livers  the  transverse  diameter  is  the  shorter, 
and  the  vertical  the  longer. 

Few  organs  present  a  greater  variation  in  size  and  form  in  different  individuals  than 
the  liver.  I  am  certain  that  the  relative  proportion  between  different  livers  may  be  as 
much  as  one  to  three,  in  the  absence  of  all  disease.  It  is  pretty  generally  believed  that 
a  large  liver  occasions  such  modifications  in  the  whole  system  as  will  give  rise  to  a  par- 
ticular temperament.  But  it  may  be  doubted  whether  there  is  any  proof  that  the  bilious 
and  melancholic  temperaments  are  specially  accompanied  by  a  large  liver,  or  that  hypo- 
chondriasis in  particular  is  the  result  of  a  predominance  of  that  organ.*  AnatomicEil 
evidence  affords  but  little  support  to  such  ideas,  which  are  rather  the  result  of  precon- 
ceived notions  respecting  the  functions  of  the  liver  and  the  influence  of  the  bile,  than  the 
fruit  of  positive  observations. 

It  varies  much  in  size  according  to  the  state  of  its  circulation  ;  when  its  vessels,  and 
especially  the  ramifications  of  the  vena  portae,  are  empty,  the  tissue  of  the  liver  shrinks, 
and  its  surface  becomes,  as  it  were,  wrinkled.  When,  on  the  other  hand,  the  hepatic 
vessels  are  injected,  the  organ  is  in  a  state  of  turgescence.  I  have  often  been  struck 
with  the  increase  in  the  size  of  the  liver  produced  by  an  injection  pushed  forcibly  and 
continuously  into  the  vena  portffi. 

The  size  of  the  liver,  as  influenced  by  age  and  disease,  deserves  particular  attention. 
I  shall  point  out  the  influence  of  age  under  the  head  of  development.  We  shall  then 
see  that  the  liver  is  largest  during  intra-uterine  life,  and  that  it  is  proportionally  larger 
at  periods  nearer  to  that  of  conception  :  hence  it  arises  that  the  greatest  relative  size 
of  the  liver  is  coincident  with  the  least  amount  of  biliary  secretion  ;  and  we  may  there- 
fore conclude  that  this  organ  has  some  other  use  besides  that  of  secreting  bile. 

When  diseased,  the  liver  has  been  found  to  weigh  from  thirty  to  forty  pounds  ;  but 
the  enormous  size  in  these  cases  is  almost  invariably  owing  to  the  development  of  acci- 

*  Hippocrates  sometimes  gave  the  name  of  hypochondria  to  the  liver,  and  hence,  no  doubt,  the  term  hypo- 
chondriac. 

Ccc 


386  SPLANCHNOLOGY. 

dental  tissues.  Some  cases,  however,  have  been  recorded  of  simple  hypertrophe  of  the 
liver  without  any  organic  disease,  in  which  the  size  acquired  was  prodigious.  In  oppo- 
sition to  this,  we  must  notice  the  state  of  atrophy*  in  which  the  liver  is  shrivelled,  and 
not  more  than  a  third,  fourth,  or  even  a  sixth  of  the  natural  size.  In  one  subject,  in 
which  the  umbihcal  vein  remained  pervious,  and  the  sub-cutaneous  abdominal  veins  were 
dilated  and  varicose,  the  liver  weighed  only  about  half  a  pound. 
The  specific  gravity  of  the  liver  is,  to  that  of  water,  as  fifteen  to  ten 
Figure. — The  liver  is  a  single  and  asymmetrictd  organ,  of  such  an  irregular  form  as  to 
defy  description.  We  shall  compare  it,  with  Glisson,  to  a  segment  of  an  ovoid,  cut  ob- 
liquely lengthwise,  thick  at  its  right  extremity,  and  progressively  diminishing  towards 
the  left,  which  terminates  in  a  tongue.  Its  shape  is  represented  by  the  sort  of  mould 
formed  by  the  right  half  of  the  diaphragm,  and  bounded  below  by  an  oblique  plane  di- 
rected upward  and  to  the  left  side  {fig.  161). 

No  organ  is  more  exactly  moulded  upon  the  surrounding  parts,  nor  undergoes  changes 
in  form  with  greater  impunity,  either  from  external  pressure  or  from  that  exercised  upon 
it  by  other  viscera  ;  it  may  even  be  said  to  be,  as  it  were,  ductile  or  malleable  under  the 
influence  of  a  slowly-exerted  pressure.  The  injurious  effects  of  very  tight  lacing  are 
chiefly  experienced  by  the  liver.  A  circular  constriction  and  a  fibrous  thickening  of  this 
organ  opposite  the  base  of  the  thorax  sometimes  afford  evidence  of  this  compression ; 
its  transverse  and  antero-posterior  diameters  become  diminished,  and  its  vertical  diam- 
eter is  increased  ;  it  projects  more  or  less  below  the  base  of  the  thorax,  descends  as  low 
down  as  the  right  iliac  fossa,  and  may  even  touch  the  brim  of  the  pelvis  without  any 
structural  lesion.  In  these  cases,  its  upper  surface  becomes  anterior,  and  its  lower  sur- 
face posterior. 

There  are  but  few  female  subjects  without  some  deformity  of  the  liver,  and,  therefore, 
the  type  of  the  organ  must  be  sought  for  in  the  male.t  No  practical  conclusions,  then, 
can  be  derived  from  the  shape  of  the  liver  ;  and  I  am  almost  inclined  to  agree  with  Ve- 
salius,  in  saying  that  it  has  no  determinate  form,  but  accommodates  itself  to  the  sur- 
rounding parts.  In  a  few  rare  exceptions,  we  find  the  human  liver  divided  into  lobules 
by  deep  fissures,  as  it  is  in  a  great  number  of  animals.  The  errors  which  have  for  a 
long  time  existed  upon  this  subject,  even  since  the  time  of  Vesalius,  arise  from  a  blind 
respect  for  the  assertions  of  older  anatomists,  who,  having  dissected  few  human  sub- 
jects, were  accustomed  to  confound,  in  their  descriptions,  the  structure  found  in  animals 
with  that  observed  in  man.    ^ 

The  liver  presents  for  consideration  a  superior  or  convex  surface,  an  inferior  or  plane 
surface,  an  anterior  and  a  posterior  border,  a  base,  and  a  summit. 

The  superior  surface  (pars  gibba)  is  convex  and  smooth,  and  in  contact  with  the  dia- 
phragm, which  is  moulded  exactly  upon  it :  this  convexity  is  not  regular,  but  much 
greater  on  the  right  than  on  the  left  side,  where  the  surface  is  almost  flat  {fig.  161). 
This  surface  is  divided  into  two  unequal  parts  {I  I')  by  a  falciform  fold  of  peritoneum  (1 
to  2),  called  the  falciform  or  suspensory  ligament  of  the  liver,  which  seems  to  be  principal- 
ly intended  to  protect  the  umbilical  vein,  and  which  is  never  put  upon  the  stretch  during 
the  natural  state  of  fulness  of  the  abdomen.  One  or  more  fissures  are  not  unfrequently 
found  running  from  before  backward  upon  the  upper  surface  of  the  liver ;  and  I  am  sure 
that  these  fissures,  in  explanation  of  which  Glisson  and  Fernel  have  advanced  some 
very  singular  opinions,  are  due,  at  least  in  some  cases,  to  the  pressure  of  projecting  folds 
of  the  diaphragm.  The  falciform  ligament  forms  the  line  of  separation  between  the 
right  {I')  and  the  left  (/)  lobes,  a  purely  nominal  distinction,  which  results  from  the  old 
habit  of  admitting  several  lobes  in  the  liver,  and  is  retained  here  only  for  the  sake  of 
conformity  to  custom.  The  portion  of  the  liver  situated  to  the  left  of  the  suspensory 
ligament  is  always  smaller  than  that  upon  the  right. 

The  convex  surface  of  the  liver  is  bounded  behind  by  the  reflection  of  the  peritoneum 
upon  it  from  the  diaphragm.  It  is  separated  by  the  diaphragm  from  the  heait,  the  ribs, 
and  the  base  of  the  right  lung.  Its  relations  with  the  base  of  the  right  lung  are  very  ex- 
tensive :  the  base  of  the  lung  and  the  convexity  of  the  liver  are  exactly  fitted  to  each 
other  ;  this  may  be  shown  by  making  a  vertical  section  from  before  backward,  upon  the 
right  side  of  the  trunk,  when  the  liver  will  be  seen  to  be  received,  as  it  were,  into  a 
deep  excavation  in  the  base  of  the  lung.  This  relation  explains  why  abscesses  and 
cysts  of  the  liver  may  burst  into  the  lung,  and  why  abscesses  of  the  lung  point  towards 
the  liver ;  why  the  liver  may  increase  in  size  in  the  direction  of  the  thorax,  and  push  up 
the  lung  as  far  as  the  third  or  even  the  second  rib  ;  and  why  effusions  into  the  pleura 
may  force  the  liver  downward  in  the  abdomen  ;  and  also  why  peritonitis,  confined  to  the 
region  of  the  liver,  is  sometimes  mistaken  for  pleurisy  at  the  base  of  the  thorax.  The 
relations  of  the  liver  with  the  seven  or  eight  inferior  ribs  account  for  the  impressions 
which  are  often  seen  upon  its  surface ;  and  also  explain  the  facts,  that  violent  blows 
upon  the  ribs  may  bruise  this  viscus  ;  that  pointed  instruments  thrust  into  the  intercos- 

*  We  cannot  admit  the  proposition  of  Soemmering,  "  Quo  sanior  homo,  eo  minus  ejus  hepar  est." 
+  Soemmering,  without  giving  any  reason,  says,  "  In  sexH  masculo  magit,  minus  in  femineo  coatis  istit  ter. 
.  turn  latet."—(Corpor.  Hum.  Fabric,  t.  vi.,  p.  163.) 


m 


THE   LIVER. 


^  spaces  on  the  right  side  may  wound  it ;  and  that  abscesses  of  the  liver  point  and 
open  between  the  ribs. 

The  relations  of  the  convex  surface  of  the  liver  Avith  the  abdominal  parietes,  which 
are  so  extensive  in  the  new-bom  infant,  and  stiU  more  so  in  the  foetus,  are  generally 
confined  in  the  adult  to  a  variable  extent  of  the  epigastrium,  and  to  a  small  space  below 
the  edges  of  the  ribs  on  the  right  side  {fig.  155).  In  certain  conformations  of  the  liver 
(almost  always  acquired),  and  in  such  diseases  as  are  attended  with  an  increased  size 
of  the  organ,  these  relations  become  much  more  extended;  and,  even  in  the  absence  of 
any  disease,  the  liver  is  not  unfrequently  found  to  extend  into  the  neighbourhood  of  the 
umbihcus,  or  even  into  the  right  iliac  region.  In  the  erect  posture,  the  liver  has  a  ten- 
dency to  project  below  the  ribs  ;  and,  therefore,  the  sitting  posture,  with  the  upper  part 
of  the  body  inclining  forward,  and  resting  upon  some  object,  is  the  most  favourable  one 
for  exploring  this  organ.*  It  is  by  no  means  rare  to  meet  with  accidental  adhesions 
between  the  liver  and  the  diaphragm,  consisting  either  of  cellular  filaments  in  the  form 
of  bands,  or  of  cellular  tissue  of  a  greater  or  less  density. 

The  inferior  or  plane  surface  {pars  sima,  1 1,  fig.  154  and  fig.  164).  This  is  much  more 
complfeated  than  the  upper  surface,  and  upon  it  the  hepatic  vessels  enter  and  make  their 
exit  from  the  liver.  Certain  eminences  and  depressions,  or  fissures  of  variable  depth, 
are  met  with  here,  which  have  led  to  the  division  of  the  liver  into  several  lobes ;  but 
that  kind  of  division,  which  in  animals  appears  to  enable  the  organ  to  adapt  itself  to  the 
form  of  the  viscera  of  the  abdomen,  and  has  probably  some  relation  with  the  conforma- 
tion of  the  heart,  cannot  be  said  to  exist  in  man.t  This  lower  surface  is  directed  down- 
ward and  backward,  and  sometimes  directly  backward  :  it  presents  for  our  consideration, 
in  the  first  place,  an  antero-posterior  fissure,  or  fissure  of  the  umbilical  vein,  called  also  the 


Fig.  16i. 


longitudinal  or  horizontal  fissure 
(uh,fig.  164),  which  extends  from 
the  anterior  to  the  posterior  bor- 
der of  the  liver,  and  is  divided  by 
the  transverse  fissure  {dp),  meet- 
ing it  at  a  right  angle,  into  two 
halves,  one  anterior,  the  other 
posterior.  The  anterior  half  lodg- 
es the  umbilical  vein  in  the  foe- 
tus,t  or  the  fibrous  cord  {u),  to 
which  it  is  reduced  in  the  adult : 
the  posterior  half  lodges  the  duc- 
tus venosus  in  the  fcetus,  or  the 
fibrous  band  {v),  by  which  it  is  re- 
placed after  birth.  The  anterior 
half  of  the  longitudinal  fissure  is 
much  deeper  than  the  posterior, 
and  is  often  converted  into  a  com- 
plete canal  by  a  sort  of  bridge 
formed  by  a  prolongation  of  the  substance  of  the  liver  :  when  incomplete,  this  bridge  is 
always  situated  near  the  transverse  fissure  :  it  often  consists  of  a  band  of  fibrous  tissue. 
Even  when  quite  complete,  it  invariably  presents  a  notch  near  the  anterior  border  of  the 
liver.  ^  The  posterior  half  of  the  longitudinal  fissure  inclines  more  or  less  obliquely  to 
the  left  of  the  lobulus  Spigelii  (3),  gives  attachment,  like  the  transverse  fissure,  to  the  gas- 
tro-hepatic  omentum,  and  communicates  with  the  fissure  for  the  vena  cava  superior  (c), 
behind  the  lobulus  Spigelii. 

The  existence  of  this  fissure  has  been  the  chief  cause  of  the  division  of  the  liver  into 
the  right  or  great  lobe  (1),  and  the  left  lobe  (2),  also  termed  the  middle-sized  lobe  by  those 
anatomists  who  admit  as  a  third  lobe  the  small  lobe,  the  lobule  or  the  lobulus  Spigelii  (3). 
This  division  of  the  liver  into  two  lobes  is  also  marked  on  the  upper  surface,  as  we  have 
already  seen,  by  the  suspensory  ligament.  Of  these  lobes,  the  right  is  much  larger  than 
the  left ;  the  former  occupies  the  right  hypochondrium,  the  latter  the  epigastrium  and 
left  hypochondrium  {fig.  161).  The  proportion  between  the  right  and  the  left  lobe  can- 
not be  precisely  determined.  The  left  lobe  is  sometimes  reduced  to  a  thin  tongue,  while, 
at  other  times,  it  is  almost  half  the  size  of  the  right  lobe.  Generally,  the  relative  pro- 
portion between  them  is  as  six  to  one.  This,  however,  is  of  but  little  consequence  ;  for 
as  the  distinction  between  the  two  lobes  is  quite  imaginary,  the  substance  of  the  left 

*  In  an  old  woman,  whose  liver  was  deformed  but  healthy,  and  projected  below  the  ribs,  I  was  able  to  diag- 
nosticate, by  mediate  percussion,  the  existence  of  a  knuckle  of  intestine  between  the  liver  and  the  parietei 
of  the  abdomen.  Very  lately  I  found  a  large  loop  of  the  transverse  arch  of  the  colon  between  the  right  lobe 
and  the  abdominal  parietes,  and  a  loop  of  the  small  intestine  between  the  left  lobe  and  those  parietes. 

t  The  ancients  admitted  four  lobes  in  the  liver,  which  they  distinguished  by  the  singular  names  of  mensa, 
porta,  gladius,  and  unguis. 

t  [The  term  umbilictil  fissure  is  often  restricted  to  this  part  of  the  longitudinal  fissure  ;  the  posterior  half  it 
then  called  the  fossa  of  the  ductus  venosus.] 

0  [This  bridge  was  purposely  divided  in  the  liver  from  which  Jig.  164  was  drawn.] 


SPLANCHNOLOGY. 

may,  without  any  inconvenience,  be  included  in  the  right,  and  vice  versa.  TKe  transverie 
fissure,  or  fissure  of  the  vena  ■porta  {d  p),  is  the  true  hilus  of  the  liver,  for  through  it  the 
hepatic  vessels  enter  and  pass  out.  It  is  a  very  broad,  transverse  fissure,  from  fifteen 
to  eighteen  lines  in  length,  occupying  ahnost  the  middle  of  the  lower  surface  of  the  liver, 
a  little  nearer  to  the  posterior  than  to  the  anterior  border,  and  to  the  left  than  to  the  right 
extremity.  It  is  bounded  on  the  left  by  the  longitudinal  fissure,  with  which  it  commu- 
nicates ;  to  the  right  of  the  gall-bladder  {g),  it  is  prolonged  obliquely  forward  by  a  deep 
and  narrow  cleft.  In  the  transverse  fissure  we  find  the  vena  portae,  or  the  sinus  (p)  of 
the  vena  portae,  the  hepatic  artery  (a),  the  roots  of  the  hepatic  duct  (d),  a  great  number 
of  lymphatic  vessels  and  nerves,  and  a  considerable  quantity  of  cellular  tissue.  The 
gastro-hepatic  omentum  is  given  off  from  this  fissure.  The  transverse  fissure  is  situa- 
ted between  two  eminences,  called  by  the  ancients  the  pillars  of  the  gate  {portal  eminen- 
ces). All  the  peculiarities  of  the  inferior  surface  of  the  liver  may  be  referred  to  these 
two  fissures. 

Thus,  to  the  left  of  the  longitudinal  fissure  we  observe  the  inferior  surface  of  the  left 
lobe,  slightly  concave  behind,  where  it  is  applied  to  the  lobulus  Spigelii,  from  which  it  is 
separated  by  the  gastro-hepatic  omentum ;  concave  in  front,  so  as  to  be  adapted  to  the 
convexity  of  the  stomach,  upon  which  it  is  prolonged  to  a  greater  or  less  extent.  This 
relation  of  the  liver  with  the  stomach  is  of  the  utmost  importance.  Thus,  when  the 
stomach  is  distended,  it  pushes  the  liver  upward  and  backward  in  such  a  manner  that 
its  lower  surface  is  directed  somewhat  forward.  In  cases  of  chronic  ulceration  of  the 
stomach,  the  tissue  of  the  liver  is  not  unfrequently  found  supplying  the  place  of  the  de- 
stroyed coats  of  the  stomach,  and  this  to  a  considerable  extent.  The  lower  surface  of 
the  left  lobe  is  often  in  relation  with  the  spleen,  which  it  occasionally  covers  like  a  helmet. 

To  the  right  of  the  longitudinal  fissure,  and  in  front  of  the  transverse  fissure,  we  find, 
upon  the  lower  surface  o'f  the  right  lobe,  the  fossa  for  the  gall-bladder,  which  is  more  or 
less  deep,  oblong,  and  directed  from  before  backward,  upward,  and  to  the  left  side,  like 
the  gall-bladder  (g)  itself,  for  the  reception  of  which  it  is  intended.  This  fossa  is  not  al- 
ways prolonged  as  far  as  the  anterior  border  of  the  liver.  Between  the  fossa  of  the  gall- 
bladder and  the  longitudinal  fissure  is  a  square  surface,  the  lobulus  quadratus,  anterior 
portal  eminence,  or  anterior  lobule  (4).  This  surface  sometimes  terminates  behind  in  a  dis- 
tinct rounded  prominence,  which  justifies  the  name  of  eminence  applied  to  it ;  at  other 
times,  on  the  contrary,  this  portion  of  the  liver  is  flattened. 

Behind  the  transverse  fissure  we  find  the  posterior  portal  eminence,  or  small  lobe  (pos- 
terior lobule  or  lobule),  also  called  the  lobulus  Spigelii  (3),  from  the  name  of  the  anatomist 
to  whom  its  discovery  has  been  attributed,  although  it  was  described,  and  even  figured 
before  his  time  by  Vesalius,  Sylvius,  and  Eustachius.  It  varies  much,  both  in  size  and 
shape,  and  is  situated  between  the  transverse  fissure  and  the  posterior  border  of  the  liver, 
and  between  the  fissure  of  the  ductus  venosus  (»)  on  the  left,  and  the  fissure  of  the  vena 
cava  inferior  (c)  on  the  right.  It  is  situated  to  the  right  of  the  oesophageal  orifice  of  the 
stomach,  opposite  its  lesser  curvature,  by  which  it  is  embraced  ;  its  form  is  that  of  a 
flattened  semilunar  tongue,  convex  upon  its  lower  and  free  surface,  which  corresponds 
to  the  upper  border  of  the  pancreas,  and  has  a  projection  in  the  centre,  surrounded  by 
an  arterial  circle,  formed  by  the  coronary  artery  of  the  stomach  with  the  splenic  and 
hepatic  arteries.  This  projection  (above  3)  is  called  by  Haller  major  colliculus  in  magna 
papilla  similitudinem;  and  by  Winslovv,  r eminence  triangulaire.  From  its  posterior  ex- 
tremity a  prolongation  is  given  off  opposite  the  posterior  border  of  the  liver,  which  con- 
verts the  fissure  for  the  vena  cava  inferior  into  a  canal  that  is  sometimes  complete.*  A 
prolongation  or  ridge  (5)  {the  right  prolongaiion  of  the  lobule)  passes  from  its  anterior  ex- 
tremity to  the  right  of  the  transverse  fissure,  and,  proceeding  obliquely  forward,  separ- 
ates the  renal  (r)  from  the  colic  (o)  depression.  This  prolongation  was  minutely  descri- 
bed by  the  older  anatomists,  and  has  been  termed  by  Haller  the  colliculus  caudatus.j  At 
its  junction  with  the  lobule,  this  prolongation  is  marked  in  front  by  a  groove  (the  groove 
of  the  vena  porta),  sufficiently  deep  to  lodge  the  vena  portae  (p)  and  the  hepatic  artery  (a) ; 
and  it  is  still  more  deeply  excavated  behind  for  the  vena  cava  inferior  (c)  {the  groove  of 
the  vena  cava  inferior).  Sometimes  the  right  margin  of  the  first-mentioned  groove  has  a 
papilla  similar  to  that  of  the  lobulus  Spigelii ;  and  in  this  case  it  might  be  Sciid  that  there 
are  two  lobes  of  Spigelius  ;  opposite  this  groove,  the  vena  portae  is  separated  from  the 
vena  cava  only  by  a  very  thin  lamina. 

The  lobulus  Spigelii  presents  much  variety  in  its  size  ;  but  not  such  as  to  enable  it  to 
be  felt  through  the  abdominal  parietes,  unless  the  enlargement  is  the  consequence  of 
disease.  Physicians  who  pretend  to  recognis.e  by  the  touch  obstruction  or  adhesion  of 
the  lobulus  Spigelii,t  are  certainly  not  anatomists. 

To  the  right  of  the  longitudinal  fissure,  the  lower  surface  of  the  liver  presents,  behind, 

*  [This  prolong-ation  did  not  exist  in  the  liver  represented  in  fig.  1G4.] 

+  [Now  termed  the  lobulus  caudatus.] 

;  Meckel  and  others  consider  that  there  is  a  right  antero-posterior,  or  longitudinal  fissure,  formed  by  the 
tossa  for  the  gall-bladder  and  the  groove  of  the  vena  cava  inferior  ;  the  latter  groove  being  partly  hollowed 
t  ut  af  the  loCulus  Spigelii,  and  partly  out  of  the  continguous  portion  of  the  right  lobe,  and  then  prolonged 
upon  the  lower  surface  of  the  liver 


THE   LIVER. 

au  excavation  of  variable  depth  and  extent  in  different  subjects ;  this  is  the  renal  im- 
pression (r) :  it  corresponds  to  the  kidney,  upon  which  it  is  exactly  moulded,  and  with 
which  it  is  loosely  united,  and  also,  though  more  loosely,  with  the  supra-renal  capsule. 
Sometimes  the  impression  for  the  capsule  is  distinct  from  that  for  the  kidney.  It  may 
be  conceived  that  this  impression  must  vary  according  as  the  liver  corresponds  to  the 
uj^er  third,  to  the  upper  half,  or  to  the  whole  of  the  right  kidney.  This  impression  is 
always  directed  backward. 

In  front  of  the  renal  impression  is  a  slight  one,  termed  the  colic  depression  (o),  which 
corresponds  with  the  angle  formed  by  the  ascending  and  transverse  colon  with  part  of 
the  transverse  colon  itself,  and  sometimes,  also,  with  the  first  portion  of  the  duodenum. 

Behind  is  the  groove  for  the  vena  cava  inferior  (c),  which  advances  slightly  upon  the 
lower  surface  of  the  liver,  on  the  inner  side  of  the  renal  and  capsular  impression. 

The  accidental  fissures  sometimes  observed  upon  the  lower  surface  of  the  liver  are 
traces  of  the  divisions  which  exist  in  a  great  number  of  mammalia. 

To  recapitulate  the  numerous  objects  seen  upon  the  lower  surface  of  the  liver,  we  find 
as  follows :  the  antero-posterior  or  longitudinal  fissure,  intersected  at  right  angles  by  the 
transverse  fissure  ;  on  the  left  of  the  antero-posterior  fissure  is  the  lower  surface  of  the 
left  lobe,  presenting  the  depression  for  the  lobulus  Spigelii,  the  gastric  impression,  and 
sometimes  the  splenic  ;  on  the  right  and  in  front  of  the  transverse  fissure,  are  the  fossa 
of  the  gall-bladder,  and  the  anterior  portal  eminence,  or  lobulus  quadratus  ;  behind  the 
transverse  fissure  is  the  posterior  portal  eminence,  or  lobulus  Spigelii,  with  its  right 
prolongation  or  lobulus  caudatus,  and  the  groove  for  the  vena  portae  ;  and  still  more  to 
the  right  are  the  renal  and  colic  impressions,  and  the  groove  for  the  inferior  vena  cava. 

The  Circumference  of  the  Liver. — The  anterior  border  of  the  liver  presents  a  very  thin, 
and,  as  it  were,  sharp  edge,  which  is  directed  obliquely  upward  and  to  the  *ft  side,  cor- 
responding to  the  base  of  the  thorax  on  the  right  side,  and  projecting  below  it,  opposite 
the  sub-sternal  notch  (Jig.  155).  Upon  this  edge  there  is  invariably  found  a  deep  notch 
(below  2,  Jig.  161)  for  the  umbilical  vein  ;  and  more  to  the  right  another  notch,  which  is 
often  larger  than  the  preceding,  and  corresponds  to  the  base  (g)  of  the  gall-bladder. 
Sometimes  there  is  merely  a  trace  of  this  notch,  and  sometimes  it  is  altogether  wanting. 
In  some  subjects  there  is  only  one  great  notch,  common  to  the  gall-bladder  and  the  um- 
bilical vein,  and  the  borders  of  it  are  sinuous,  or  cut  into  small  notches.  It  is  almost 
always  possible,  when  the  parietes  of  the  abdomen  are  relaxed,  to  insinuate  the  fingers 
between  the  ribs  and  the  liver. 

The  posterior  border  of  the  liver  is  very  thick  in  all  that  part  which  corresponds  to  the 
right  side,  and  becomes  gradually  thinner  as  it  approaches  the  left  extremity.  This 
border,  which  is  short,  rounded,  and  curved,  so  as  to  fit  the  convexity  of  the  vertebral 
column,  adheres  intimately  to  the  diaphragm  by  rather  dense  cellular  tissue.  The  peri- 
toneum is  reflected,  both  above  and  below  this  border,  from  the  diaphragm  to  the  liver, 
to  form  what  is  called  the  coronary  ligament.  The  cellular  interved  between  these  two 
layers  of  peritoneum  is  of  irregular  form,  and  taries  in  size.  This  border  is  divided  into 
two  parts  by  a  deep  notch,  which  forms  two  thirds  or  three  fourths  of  a  canal  for  the  re- 
ception of  the  inferior  vena  cava  {c,Jig.  164).  This  notch  is  converted  into  a  complete 
canal,  sometimes  by  a  sort  of  fibrous  bridge,  and  sometimes  by  a  prolongation  fi-om  the 
posterior  extremity  of  the  lobulus  Spigelii.  In  order  to  comprehend  the  arrangement  of 
the  liver  opposite  this  notch  for  the  vena  cava,  that  vein  should  be  slit  open,  and  we  then 
see  at  the  bottom  of  a  deep  notch  a  large  cavity,  into  which  all  the  hepatic  veins  (Ji  h) 
open.  We  observe,  also,  that  the  antero-posterior  fissure  is  continuous  with  the  fissure 
of  the  vena  cava,  behind  the  lobulus  Spigelii.  This  lobule,  viewed  from  behind,  appears 
like  a  tongue  detached  from  the  rest  of  the  liver,  by  circumscribing  fissures  and  grooves. 

On  the  right  side,  the  liver  terminates  in  a  thick,  smooth  extremity,  forming  the  base 
of  the  pyramid,  to  which  this  organ  has  been  compared.  A  triangular  fold  of  peritone- 
um, caUed  the  right  triangular  ligament  (/),  is  stretched  from  the  middle  of  this  thick  ex- 
tremity to  the  diaphragm. 

On  the  left  side,  the  liver  terminates  in  an  angular  or  obtuse  tongue,  more  or  less  elon 
gated,  and  sometimes  reaching  as  far  as  the  spleen,  to  which  I  have  seen  it  adherent 
This  prolongation,  which  is  attached  to  the  diaphragm  byatriangular  fold  of  peritoneum, 
called  the  left  triangular  ligament  (3,  fig.  161 ;  I,  fig.  164),  is  slightly  notched  behind  for 
the  lower  end  of  the  oesophagus,  which  is  bordered  by  it  upon  the  left  side.  In  one  sub- 
ject I  saw  this  tongue  completely  separated  from  the  rest  of  the  liver,  with  the  excep- 
tion of  a  veiscular  pedicle  about  four  lines  in  length.  This  peculiarity  was  probably  ow- 
ing to  traction  exercised  by  the  spleen,  to  which  the  prolongation  from  the  Uver  was  in- 
timately adherent. 

Colour. — The  liver  is  of  a  reddish-brown  colour,  the  depth  of  which  varies  in  different 
individuals.  Its  surface,  and  also  sections  of  it,  resemble  in  appearance  a  granite  com- 
posed of  two  kinds  of  grains,  the  one  deep  brown,  the  other  yellowish ;  and  hence  has 
arisen  the  distinction  between  the  two  substances  of  the  Uver.  In  no  tissue  in  the  body 
is  there  greater  variety  in  colour  than  in  that  of  the  liver.  Independently  of  the  differ- 
ent shades,  which  it  is  imoossible  to  describe,  the  liver  is  sometimes  of  a  yellowish  or 


390  SPLANCHNOLOGY. 

canary-yellow,  or  a  chamois-yellow  (hence  the  name  cirrhosis  given  to  a  particular  dis- 
.ease  of  the  liver) ;  or  it  may  be  of  a  more  or  less  deep  olive-green  hue,  or  of  a  slate 
colour.  These  differences  in  colour,  which  have  not,  perhaps,  been  sufficiently  investi- 
gated, are  connected  with  more  or  less  decided  alterations  of  texture.  The  chamois- 
yellow  colour  almost  always  indicates  the  existence  of  fatty  degeneration. 

Fragility. — ^The  fragility  of  the  liver  is  one  of  the  most  important  particulars  in  its  de- 
scription. It  is  compact  and  fragile,  and  cannot,  therefore,  be  forcibly  compressed  with- 
out suffering  laceration  ;  hence  the  danger  of  contusions  in  the  region  of  the  liver,  and 
the  rules  laid  down  by  accoucheurs  for  avoiding  all  compression  of  the  abdomen  of  the 
feet  us  during  the  manipulations  required  in  protracted  labours.  The  fragility  and  the 
weight  of  the  liver  explain  the  occurrence  of  injuries  of  that  organ  by  contre-coup,  after 
falls  from  an  elevated  height.  In  fatty  degeneration  of  this  organ,  the  liver  retains  the 
impression  of  the  finger,  and  its  fragility  is  in  a  great  measure  lost.  Olive-green  and 
slate-coloured  livers  are  dense,  their  molecules  are  much  more  closely  united,  and  they 
are  lacerated  with  difficulty. 

Texture. — Before  the  admirable  works  of  Glisson  and  Malpighi,  anatomists  were  in  the 
habit  of  saying,  with  Erasistratus,  that  the  liver,  like  all  other  organs  of  a  complicated 
structure,  was  a  parenchyma ;  a  vague  term,  intended  to  imply  the  effusion  of  a  particular 
juice  around  a  series  of  vessels.  Malpighi  showed,  in  opposition  to  the  assertion  of 
Warthen,  that  the  liver  is  a  conglomerate  gland  :  he  examined  the  glandular  granules 
(the  lobules  of  Kiernan),  which  Ruysch  subsequently,  by  means  of  his  beautiful  injec- 
tions, appeared  to  convert  into  vessels.  Anatomists  are  still  divided  between  the  opin- 
ions of  these  two  eminent  observers  concerning  the  intimate  structure  of  the  liver,  as 
well  as  of  all  other  glands,  some  believing  it  to  be  granular,  others  that  it  is  vascular. 
We  have  to' consider  the  coverings,  and  then  the  proper  tissue  of  the  liver. 

The  Coverings  of  the  Liver. — These  are  two  in  number,  viz.,  a  peritoneal  coat,  and  a 
proper  fibrous  membrane. 

The  peritoneal  coat  forms  an  almost  complete  covering  for  the  liver ;  the  posterior  bor- 
der, the  transverse  fissure,  the  groove  for  the  vena  cava,  and  the  fossa  for  the  gall-blad- 
der, are  the  only  parts  that  are  destitute  of  this  coat.  The  peritoneum,  from  being  re- 
flected upon  the  liver  from  the  diaphragm,  constitutes  the  several  folds  called  the  falci- 
form, coronary,  and  triangular  ligaments,  of  which  we  have  already  spoken.  By  means 
of  this  membrane,  which  is  always  moist,  the  liver  is  enabled  to  glide  upon  the  adjacent 
parts  without  friction.  We  frequently  find  cellular  adhesions  between  the  liver  and  sur- 
rounding structures,  which  do  not  positively  impair  its  functions.  The  peritoneal  coat 
adheres  intimately  to  the  proper  membrane. 

The  proper  or  fibrous  membrane  is  very  well  seen  over  such  portions  of  the  liver  as  are  not 
covered  by  the  peritoneum,  and  from  these  points  it  can  be  easily  traced  over  the  whole 
of  the  remainder  of  the  organ.  It  constitutes  the  immediate  investment  of  the  liver ;  its 
outer  surface  is  adherent  to  the  peritoneal  coat,  and  its  inner  surface  is  connected  with 
the  tissue  of  the  liver  by  means  of  fibrous  prolongations  interposed  between  the  granules 
(lobules),  affording  to  each  a  distinct  covering. 

It  passes  into  and  lines  the  transverse  fissure,  and  is  prolonged  around  the  correspond- 
ing divisions  of  the  vena  portae,  the  hepatic  artery,  and  the  biUary  ducts,  so  as  to  form 
cylindrical  sheaths  for  those  groups  of  vessels,  and  for  all  their  farther  divisions  and  sub- 
divisions. These  sheaths  constitute  the  capsule  of  Glisson,  which  we  must  therefore  re- 
gard as  a  dependance  of  the  proper  fibrous  coat.  The  internal  surface  of  these  sheaths 
is  united  to  the  vessels  only  by  a  very  loose  cellular  tissue.  Their  external  surface  ad- 
heres intimately  to  the  tissue  of  the  liver  by  fibrous  prolongations,  which  interlace  in 
every  direction,  and  form  distinct  coverings  for  the  deep-seated  granules,  analogous  to 
those  which  we  have  already  stated  are  produced  from  the  proper  coat.  The  liver, 
therefore,  is  traversed  in  all  directions  by  very  delicate  fibro-cellular  prolongations,  form- 
ing a  vast  network,  in  which  the  granules  are  contained.  This  proper  coat,  moreover, 
is  fibrous,*  not  muscular,  as  Glisson  believed. 

It  may  be  said,  with  truth,  to  constitute  the  skeleton  or  framework  of  the  liver,  for  it 
affords  a  general  covering  for  the  organ ;  it  is  prolonged  around  the  vena  portae,  the  he- 
patic artery,  and  the  biliary  ducts,  and  it  furnishes  a  fibrous  or  cellular  covering  for  each 
of  the  granules  composing  the  proper  tissue  of  the  liver.  The  fibrous  cells  thus  fonned 
become  very  distinct  in  certain  cases  of  hepatic  disease.  In  fact,  this  fibrous  tissue  not 
unfrequently  becomes  so  much  hypertrophied,  that  some  of  the  glandular  granules  are 
compressed  and  atrophied  ;  and  then  larger  or  smaller  portions  of  the  liver  appear  to  be 
converted  into  a  reticulated  fibrous  tissue.  The  arrangement  of  the  fibrous  tissue  is  also 
very  manifest  in  cases  of  softening  of  the  granules,  which  may  then  be  easily  scraped 
out  of  their  cells,  and  the  surface  of  the  section  thus  treated  presents  the  appearance  of 
the  cells  in  a  honeycomb. 

The  Proper  Tissue  of  the  Liver. — The  first  thing  that  strikes  an  observer  in  examining 
the  structure  of  the  liver,  is  the  smoothness  of  its  external  surface,  which  does  not  pre- 
sent any  of  the  lobulated  appearance  of  most  other  glands.     If  we  attentively  examine 

*  [It  is  composed  of  dense  cellular  or  fibro-cellular  tissue  :  for  its  use,  see  note,  p.  393.1 


THE  LIVER.  391 

this  surface,  either  before  or  after  the  removal  of  its  coverings,  we  find  that  it  is  most 
distinctly  composed  of  granules  (lobules,  Kieman) :  the  same  is  also  rendered  evident  by 
making  sections  of  the  organ,  or  by  tearing  it :  the  granular  arrangement  has,  it  is  true, 
been  supposed  to  be  the  result  of  laceration. 

From  the  mottled  appearance  of  the  liver  (like  granite),  already  noticed,  anatomists 
have  admitted  the  existence  of  two  substances,  or,  rather,  two  kinds  of  granules  in  this 
organ,  viz.,  reddish  brown  and  yellow  granules.  This  distinction  was  first  made  by  Fer- 
rein  (Hist.  Acad,  des  Sciences,  1735) ;  it  is  now  generally  recognised,  and  has  even  served 
as  the  basis  of  several  more  or  less  ingenious  explanations.  This  anatomist  called  the 
brown  substance  medullary,  and  the  yellow  cortical,  names  evidently  derived  from  a  rude 
analogy  between  them  and  the  medullary  and  cortical  substances  of  the  brain.  Others 
have  reversed  the  meaning  of  these  two  words  ;  but  that  is  of  little  consequence. 

"  These  two  substances,"  says  Meckel,  "  are  not  arranged  as  in  the  brain,  one  exter- 
nal and  the  other  internal ;  but  alternately  throughout  the  whole  liver,  the  yellow  sub- 
stance forming  the  mass  of  the  organ,  and  the  brown  substance  occupying  the  intervals." 
This  distinction  into  two  substances  does  not  appear  to  me  to  be  well  founded.  The 
error  has  arisen  from  assuming  as  constant  the  existence  of  two  colours,  which,  how- 
ever, are  far  from  being  distinguishable  in  all  subjects.  The  two  colours,  yellow  and 
brown,  when  they  do  exist,  do  not  belong  to  two  distinct  granules,  but  rather  to  the  same 
granule,  which  is  yellow  in  the  centre,  where  the  bile  is  found,  and  reddish  brown  at  the 
circumference,  where  the  blood  is  collected.* 

The  granules  of  the  human  liver  are  so  small,  that,  excepting  when  they  become  con- 
siderably enlarged,  it  is  not  well  adapted  for  examination.  The  liver  of  the  pig,  in  which 
the  granules  are  naturally  very  large,  appears  to  me  the  best  suited  for  this  purpose.  I 
have  been  accustomed  to  divide  the  liver  in  different  directions,  to  slit  up  and  remove 
the  veins  which  have  been  cut  across,  and  afterward  to  examine  the  granules  in  the 
semi-canals  {g  g,fig.  165 ;  c  c,fig.  166)  which  they  then  form.  The  granules  (/ 1 1)  may 
thus  be  separated  with  the  greatest  facility ;  they  are  small,  ovoid,  elliptical,  or,  rather, 
polyhedral  bodies,  having  five  or  six  surfaces,  and  shaped  so  as  to  be  moulded  upon  the 
surface  of  the  adjacent  granules,  without  leaving  any  interval.  It  is  evident,  therefore, 
that  there  is  only  one  order  of  granules  ;  that  these  granules  are  not  arranged  in  lobules, 
as  stated  by  Malpighi,+  but  are  merely  in  juxtaposition  ;  and  that  each  has  its  proper  cap- 
sule, formed  by  prolongations  of  the  fibrous  coat.  And  as  these  granules  can  be  isolated, 
and  detached  from  the  capsules  in  which  they  are  merely  lodged,  without  adhering  to 
them,  except  at  the  points  by  which  they  receive  and  emit  their  vessels,  it  follows  that 
they  are  independent  of  each  other,  and  that  the  most  complete  alteration  of  one  or  more 
of  them  may  take  place,  without  the  adjacent  or  intermediate  granules  being  in  any 
way  affected,  or,  at  least,  that  such  alteration  would  not  be  propagated  by  continuity  of 
tissue. 

The  size  of  the  granules  varies  much  in  different  individuals,  and  is  quite  independent 
of  the  size  of  the  liver  itself  Physicians  who  have  paid  much  attention  to  pathological 
anatomy  have  often  mentioned  their  increased  development,  by  the  name  of  hepar  aci- 
nosum.  This  disease  is  characterized  by  the  simultaneous  occurrence  of  atrophy  of  the 
entire  organ,  which  is  reduced  to  one  half  or  one  third  its  original  size,  and  of  hyper- 
trophy of  the  granules  themselves.  In  what  is  called  cirrhosis,  the  greater  number  of  the 
granules  are  atrophied,  t 

The  investigation  of  the  structure  of  the  liver  is,  then,  reduced  to  the  determination  of 
the  arrangement  of  the  granules  with  respect  to  each  other,  of  the  mode  in  which  the 
vessels  are  arranged,  and  of  the  structure  of  each  granule. 

1.  The  arrangement  of  the  granules,  with  regard  to  each  other,  is  revealed  by  the  fol- 
lowing fact :  In  the  disease  of  the  liver  called  ramollisement  {Diet,  de  Med.  et  Chir.  Pratiq., 
art.  Maladies  du  Foie),  in  which  that  organ  is  reduced  to  a  sort  of  pulp,  as  soon  as  the 
investing  membranes  are  torn,  the  tissue  of  the  liver  escapes  like  a  brownish-yellow 
pulp,  which,  as  it  is  not  fetid,  cannot  be  supposed  to  be  the  result  of  gangrene.  If  this 
pulp  be  placed  in  water,  myriads  of  small  and  very  distinct  yellow  granules  will  be  seen, 
resembling  small  raisin  stones,  and  appended  to  the  ramifications  of  the  different  kinds 
of  vessels  by  vascular  pedicles. 

This  fact,  which  I  have  several  times  observed,  is  confirmed  by  the  observations  of 
Harvey,  who,  in  his  work  upon  the  generation  of  animals,  says,  that  the  tissue  of  the 
liver  is  formed  along  the  umbilical  vessels  like  a  grape  on  its  footstalk,  a  bud  on  the  end 
of  a  twig,  or  an  ear  of  corn  springing  from  its  stalk ;  and  also  by  reference  to  compara- 

*  See  note,  p.  395. 

t  [This  statement  illustrates  the  confusion  that  has  prevailed  from  the  terms  lobule  and  acinus  having'  been 
employed  by  anatomical  writers  in  different  senses  to  those  attached  to  them  by  Malpighi ;  the  lobule  of  Mal- 
pighi  is,  in  fact,  equivalent  to  the  granule  of  M.  Cruveilhier,  and  was  described  by  him  as  consisting  of  a  col- 
lection of  acini  {see  note,  p.  395).] 

t  The  ingenious  explanation  which  has  been  given  of  cirrhosis  is,  then,  destitute  of  foundation.  In  cirrhosis, 
as  I  have  shown  in  another  place,  there  is  neither  atrophy  of  the  red  substance,  nor  hypertrophy  of  the  yellow, 
but  rather  atrophy  of  the  greater  number  of  granules,  with  hypertrophy  and  yellow  discoloration  of  the  re- 
mainder. 


392  SPLANCHNOLOGY, 

tive  anatomy,  for  M.  Blainville  has  informed  me  that,  in  certain  species  of  animals,  the 
liver  is  formed  by  rows  of  glandular  granules  attached  aJong  the  vessels.* 

2.  The  Vessels  of  the  Liver. — The  study  of  the  vessels  of  the  liver  is  one  of  the  most 
important  points  in  the  history  of  that  organ.  Besides  the  arteries  and  veins  correspond- 
ing to  those  of  other  parts  of  the  body,  the  liver  receives  also  a  special  system  of  veins, 
viz.,  the  system  of  the  vena  porta,  which  is  distributed  in  its  interior  like  an  artery.  It 
presents  also,  in  the  adult,  the  remains  of  a  venous  system  peculiar  to  the  foetus,  the  sys- 
tem of  the  umbilical  vein ;  and,  lastly,  it  contains  canals  intended  for  the  conveyance  of 
the  bile,  named  the  biliary  ducts. 

The  special  venous  system  of  the  liver,  or  the  system  of  the  vena  porta,  will  be  described 
more  particularly  in  another  place.  I  shall  only  now  observe,  that  the  branches  of  ori- 
gin of  this  system  commence  in  all  the  abdominal  organs  concerned  in  the  function  of 
digestion  ;  that  the  ventral  venaportae,  resulting  from  the  union  of  these  branches,  reaches 
the  transverse  fissure  of  the  liver,  and  divides  there  into  a  right  and  left  branch,  which 
constitute  the  hepatic  vena  portae  {p,  fig.  164) ;  and  that  these  branches  subdivide  and 
spread  into  all  parts  of  the  liver,  some  forward  and  others  backward,  but  all  following  a 
transverse  direction.  The  capsule  of  Glisson,  as  we  have  seen,  is  developed  around  this 
vein ;  so  that,  in  sections  of  the  liver,  the  branches  of  the  vena  portae  can  always  be  rec- 
ognised by  these  two  characters  :  a  transverse  direction,  and  the  presence  of  the  capsule. 
Remmtis  of  the  Umbilical  Vein. — We  can  easily  conceive  the  arrangement  of  these  re- 
Fig.  164.t  mains,  if  we  consider  that,  in  the  foetus,  the  umbilical 

vein  (m,  fig.  164t),  proceeds  from  the  placenta  to  the 
longitudinal  fissure  of  the  liver ;  and  at  the  point  where 
this  is  intersected  by  the  transverse  fissure,  divides  into 
two  branches,  one  of  which,  under  the  name  of  the  duc- 
tus venosus  (d),  passes  directly  to  the  vena  cava  (c),  at 
the  point  where  it  traverses  the  posterior  border  of  the 
liver ;  while  the  other  is  continuous  with  the  hepatic 
vena  portae  (jf),  which,  as  we  have  seen,  occupies  the 
transverse  fissure.  The  portion  common  to  the  umbil- 
ical and  portal  veins  remains  pervious  in  the  adult ;  but 
it  then  belongs  exclusively  to  the  vena  portae.  The  ductus  venosus  then  becomes  a  mere 
fibrous  cord  {v,  fig.  164t),  as  well  as  the  trunk  of  the  umbilical  vein  itself  (m).  It  is  not 
rare  to  find  the  trunk  of  the  umbilical  vein  persistent  in  the  adult,  from  an  abnormal  com- 
munication between  it  and  the  veins  of  the  abdominal  parietes.  (See  Anat.  Path,  avec 
planches,  liv.  xvii.,  pi.  6.)  No  example  has  been  recorded  of  a  persistent  ductus  venosus. 
Arteries. — The  hepatic  artery  is  a  branch  of  the  coeliac  axis  {t,fig.  154),  which  also 
furnishes  branches  to  the  spleen  and  the  stomach  ;  and  although  a  difference  in  the  ori- 
gin of  an  artery  dose  not  occasion  any  difference  in  the  blood  within  it,  yet  this  com- 
munity of  origin  is  not  the  less  remarkable,  for  it  seems  to  denote  a  community,  a  coinci- 
dence, or  a  connexion  of  function.  Moreover,  as  the  nervous  plexuses  are  supported 
upon  the  arteries,  it  follows  that  the  nerves  of  the  spleen,  stomach,  and  liver,  are  de- 
rived from  a  common  plexus,  the  cceMac.  We  frequently  find  a  second  hepatic  artery 
arising  from  the  superior  mesenteric. 

I  must  not  omit  to  mention  the  smaUness  of  the  hepatic  artery  in  comparison  with  the 
size  and  mass  of  the  liver.  In  this  respect  few  organs  present  so  great  a  disproportion  : 
compare,  for  example,  the  kidney  and  the  renal  artery,  look  at  the  muscles,  and  I  may 
almost  say  at  the  bones.  The  small  caliber  of  the  hepatic  artery  enables  us  to  determine 
d  priori,  that  it  cannot  serve  both  for  the  nutrition  of  the  organ  and  for  the  secretion  of 
the  bile.  Lastly,  it  exactly  follows  the  r2unifications  of  the  vena  portae  and  the  biliary 
ducts,  and  the  capsule  of  Glisson  is  common  to  it  and  to  those  two  sets  of  vessels. 

The  Hepatic  Veins. — The  hepatic  veins,  the  efferent  vessels  of  the  liver,  are  not  pro 
portion al  to  the  size  of  the  hepatic  artery,  but  to  that  of  the  vena  portae.  Proceeding 
from  all  points  of  the  liver,  and  converging  towards  the  fissure  of  the  vena  cava,  the 
hepatic  veins  {h  h',fig.  164)  empty  themselves  into  that  vein  (c),  especially  near  the  pos- 
terior border  of  the  liver.  It  follows,  therefore,  that  the  direction  of  the  hepatic  veins 
and  of  their  divisions  is  from  before  backward,  while  that  of  the  divisions  of  the  vena 
portae  is  transverse. t    This  direction,  and  the  absence  of  the  capsule  of  Glisson,  on  ac- 

*  Arrangement  of  the  ioiuZe^.— [According  to  M.  Kieman,  from  whose  paper  in  the  Phil  Trans,  for  1833 
this  and  the  succeeding  notes  on  the  structure  of  the  liver  are  derived,  the  lobules  (g^ranules,  Cruveilhier)  of 
the  human  liver  are  many  sided  bodies,  flattened  on  one  surface,  called  the  base,  and  forming-  processes  in 
every  other  direction  ;  hence,  in  a  longitudinal  section  they  present  a  foliated,  and  in  a  transverse  section  a 
polyhedral  form.  The  bases  of  all  the  lobules  (c  c,fig.  166)  rest  on  certain  branches  of  the  hepatic  vein,  call- 
ed «u4-lobular  veins  (A  h)  ;  while  their  other  surfaces,  surrounded  by  the  capsular  investments,  are  either  in 
contact  with  those  of  the  adjacent  lobules,  or  appear  on  the  outer  surface  of  the  liver,  or  in  the  portal  canals 
^g  gifig-  '65).  which  contain  the  \4ka.  portae,  hepatic  artery,  and  hep.atic  duct,  or  in  those  fur  the  lars^er  trunks 
(h,fig.  166)  of  the  hepatic  vein.  The  intervals  between  the  sides  of  the  lobules  are  the  inter-l(>bular/«s«r««, 
and  the  points  at  which  two  or  more  of  ihese  meet  are  the  inter-lobular  spaces.  The  superficial  lobules  are 
imperfect,  or  more  or  less  flattened  on  their  exposed  side.] 

t  At  least  in  the  principal  t'orVs  ;  for  there  are  a  great  number  of  ramifications  of  the  hepatic  veins  which 
pass  transversely. 


THE    LIVEE. 


393 


count  of  which  the  walls  of  these  veins  are  directly  adherent  to  the  tissue  of  the  liver, 
so  that  the  veins  themselves  remain  patent,  while  the  sections  of  the  vena  portae  collapse, 
are  the  two  characters  by  which  the  divisions  of  the  hepatic  veins  may  be  distinguished 
from  those  of  the  vena  portae,  on  simply  inspecting  a  section  of  the  liver.  Do  these 
anatomical  differences  between  the  two  kinds  of  veins  produce  any  difference  in  the 
mechanism  of  the  circulation  through  them  ]  And  is  the  want  of  immediate  connexion 
of  the  divisions  of  the  vena  portae  to  the  tissue  of  the  liver  intended  to  permit  them  to 
contract  so  as  to  propel  the  blood  ]  If  we  consider  that  the  blood  of  the  vena  portae  pro- 
ceeds from  the  trunk  towards  the  branches,  as  in  the  arteries,  we  may  conceive  the  ad- 
vantages which  must  result  from  an  anatomical  arrangement  that  would  allow  these 
vessels  to  exert  a  direct  pressure  upon  the  blood. 

Another  point  of  difference  between  the  branches  of  the  hepatic  vein  and  of  the  vena 
portae  is,  that  the  walls  of  the  former  are  perforated  by  a  multitude  of  extremely  small 
openings  or  pores,  which  are  the  orifices  of  very  small  veins. 

The  Lymphatic  Vessels. — The  lymphatics  of  the  liver  are  so  numerous  that  these  ves- 
sels were  first  discovered  in  that  organ  ;  indeed,  it  was  for  a  long  time  regarded  as  the 
origin  of  the  lymphatic  system,  just  as  it  had  been  originally  considered  the  origin  of  the 
veins.  The  lymphatics  of  the  liver  form  a  superjicicd  and  a  deej>  set.  The  superficial 
lymphatics  are  arranged  in  an  extremely  close  network  under  the  peritoneal  coat.  Tlie 
deep  set,  which  are  very  large  and  numerous,  pass  out  of  the  transverse  fissure  of  the 
liver,  and  terminate  partly  in  lymphatic  glands  situated  along  the  hepatic  vessels,  and 
partly  in  the  lumbar  glands.  They  communicate  directly  and  freely  with  the  thoracic 
duct,  so  that  one  of  the  best  methods  of  injecting  this  duct  consists  in  throwing  the  in- 
jection into  the  lymphatics  of  the  liver. 

The  Nerves. — These  are  very  small,  considering  the  size  of  the  liver.  They  are  deri- 
ved from  two  sources,  the  cerebro-spinal  and  the  ganglionic  gystems.  The  former  are 
branches  of  the  pneumogastric  nerves  ;  the  latter  constitute  the  hepatic  plexus,  which 
is  an  offset  from  the  solar  plexus.  They  are  interlaced  around  the  hepatic  artery :  some 
of  these  nerves,  however,  by  a  special  exception,  accompany  the  vena  portae.  It  is  gen- 
eredly  admitted  that  a  few  filaments  of  the  phrenic  nerve  are  given  to  the  liver. 

The  Biliary  Ducts. — Wiiatever  may  be  the  origin  of  the  biliary  ducts,  their  radicles, 
however  small  they  may  be,  are  always  found  in  the  capsule  of  Glisson,  together  with 
the  corresponding  branches  of  the  vena  portae  and  hepatic  artery.  These  radicles  are 
united  like  veins  into  smaller,  and  these  into  larger  branches,  which,  at  length,  consti- 
tute the  hepatic  duct  (d,fig.  164).  They  can  be  readily  distinguished  from  the  other  vas- 
cular canals  of  the  liver  by  their  yellowish  colour,  by  the  fluid  which  they  contain,  and 
by  the  appearance  of  their  parietes.* 


*  Vessels. — [The  first  divisions  ef  the  vena  portae,  hepatic  artery,  and  hepat- 
ic duct,  are  situated  in  the  portal  canals,  which  are  tubular  passages  formed 
in  the  tissue  of  the  liver,  commencing  at  the  transverse  fissure,  and  branching 
through  the  Substance  of  the  organ.  The  smallest  divisions  of  the  portal  ca- 
nals contain  one  principal  branch  of  each  of  these  vessels  (P  a  d,fig.  165) : 
from  these  proceed  smaller  branches,  called  vaginal,  from  their  situation  with- 
in the  capsule  of  Glisson.  jf 

In  the  larger  canals,  the  vaginal  veins  (p"  form  a  plexus  in  the  substance 
■p  of  the  capsule,  and  then  give  off  the  tn(er-lobular  veins  (p  p),  which  pass  be- 
tween the  lobules  opposite  the  inter-lobular  spaces,  ramify  in  the  inter-lobular 
fissures  (p  p,fig.  167),  and,  after  freely  anastomosing  upon  the  capsular  surfa- 
ces of  the  lobules,  divide  into  branches,  which  penetrate  the  lobules  them- 
selves. In  the  smaller  portal  canals,  the  vaginal  venous  plexuses  are  less  ap- 
parent, for  many  of  the  inter-lobular  veins  (i)  arise  at  once  from  the  principal 
branch  of  the  vena  portae  :  where  Fig.  166^ 

this  occurs,  the  capsule  of  Glis- 
son is  very  thin  ;  and,  indeed,  the 
chief  use  of  this  structure,  in  oth- 
er situations,  appears  to  be  to  form  a  web,  on  which  the  vessels 
may  ramify,  so  as  to  enter  the  liver  at  a  great  number  of  points, 
a  use  analogous  to  that  of  the  pia  mater  and  periosteum,  in  refer- 
ence to  the  brain  and  bones. 

The  hepatic  artery  also  forms  vaginal  plexuses  in  the  portal 
canals,  wiiich  give  off  inter-lobular  hranches  ;  from  these  vessels 
the  proper  capsule  of  the  liver,  the  capsule  of  Glisson,  the  cap- 
sules of  the  lobules,  and  the  coats  of  the  different  vessels,  derive 
their  nutrier.'.  aT*«ries,  which  terminate  in  veins  that  enter  the 
vena  portse.  But  few  arterial  branches  enter  the  lobules  them- 
selves. 

The  hepatic  duct,  also,  has  its  vaginal  branches,  but  it  is  doubt- 
ful whether  they  anastomose  ;  they  are  formed  by  the  union  of 
the  inter-lobular  branches  (d  d,fig.  168),  which  do  appear  to  anas- 
tomose, and  are  derived  from  the  biliary  ducts,  which  pass  out  at 
the  surface  of  the  lobules. 

The  several  divisions  of  the  hepatic  veins  are  termed  the  he- 
patic venous  trunks,  the  su6-lobular  veins,  and  the  infra-lobular 
veins.    The  inira-lobular  veins  (i,fig.  166  ;  h,fig.  167),  of  which      , 
but  one,  independent  of  the  rest,  emerges  from  the  centre  of  the  * 

base  of  each  lobule,  open  into  the  sub-lobular  veins  (A  A),  through  -  .  •/  ■<     r   v 

the  thin  walls  of  which  can  be  seen  the  polyhedral  bases  of  the  lobules,  and  the  central  orifices  (t  t )  of  Ul0 

D  n  D 


394  SPLANCHNOLOGY. 

3.  What  is  the  structure  of  the  gramdcs  ?  In  examining  a  section  of  the  liver  of  a  pig 
with  the  simple  microscope,  I  have  seen  most  distinctly  that  each  granule  has  a  porous 
and  spongy  appearance,  like  the  pith  of  the  rush  or  elder,  so  that  the  proper  tissue  of  the 
liver  resembles  a  sort  of  filter.  This  appearance  was  much  more  distinct  in  livers  which 
I  had  injected  with  walnut  oil,  either  pure  or  coloured  blue.  The  colouring  matter  thrown 
into  the  vena  portae  was,  as  it  were,  infiltrated  into  the  spongy  tissue  of  the  liver. 

If  we  endeavour  to  ascertain  the  structure  of  the  liver  by  means  of  injections,  we  shall 
see  what  was  observed  by  Soemmering,  that  whichever  vessel  be  injected,  whether  the 
hepatic  artery,  the  duct,  the  vena  portae,  or  the  hepatic  vein  (provided  only  the  injection 
be  thin,  as,  for  example,  coloured  glue,  size,  or  spirits  of  turpentine,  or,  better  still,  a 
strong  aqueous  solution  of  gamboge),  there  will  not  be  a  single  granule  into  which  the 
injection  will  not  have  penetrated ;  and,  moreover,  that  the  liquid  throvra  into  one  ves- 
sel will  pass  either  into  one,  two,  or  all  three  of  the  others  ;  and  the  facility  with  which 
this  takes  place  proves  that  the  different  orders  of  vessels  communicate  with  each  other 
directly,  and  not  through  the  medium  of  cells  or  small  cavities.* 

In  a  foetus,  or  an  infant  that  has  died  immediately  after  birth,  an  injection  through  the 
umbilical  vein  gives  similar  results.  I  have  never  been  able  to  force  the  liquid  into  the 
l)Tnphatic  vessels,  at  least  without  rupturing  the  tissue  of  the  liver.  Air  driven  into  the 
vessels  penetrates  more  easily  than  liquids  into  the  lymphatics,  no  doubt  on  account  of 
its  greater  subtilty. 

It  follows,  then,  that  in  each  granule  there  is  an  arterial  radicle,  a  radicle  of  the  vena 
portae,  one  of  the  hepatic  vein,  and  one  of  the  duct,  probably  some  lymphatic  vessels,  and 
a  nervous  filament.  The  aggregate  has  been  represented  by  Soemmering  as  having 
some  resemblance  to  the  arrangement  of  a  Damask  rose.f  All  the  different  vessels 
communicate  freely  with  each  other.t 

The  manner  in  which  these  different  vessels  are  arranged  in  each  granule  can  only 
be  discovered  by  injecting  them  simultaneously,  or,  rather,  successively,  for  it  is  nearly 
impossible  to  inject  all  the  vessels  of  the  liver  at  the  same  time.  I  have  accordingly  in- 
jected the  vessels  in  the  following  order :  the  vena  cava,  and,  consequently,  the  hepatic 
veins,  with  wax  coloured  with  Prussian  blue — a  certain  quantity  of  walnut  oil,  also  con- 
taining Prussian  blue,  had  been  previously  thrown  into  the  same  vein  ;  the  vena  portee 
with  a  red  injection ;  the  hepatic  artery  with  the  same  ;  and  then  the  hepatic  duct  with 
a  yellow  injection.  These  injections  were  made  in  the  liver  of  a  pig,  the  liver  being 
placed  in  warm  water,  and  the  injections  pushed  in  with  a  gradually-increasing  force. 
During  the  injection  of  the  vena  cava  and  vena  portae,  the  wrinkles  of  the  liver  disap- 
peared, and  the  central  depressions  of  the  superficial  granules  became,  on  the  contrary, 
slightly  prominent.  It  was  therefore  evident  that  each  granule  was  hollow,  and  that 
the  space  had  been  filled  by  the  injected  matter. 

The  liver  thus  injected  and  submitted  to  different  chemical  agents  gave  the  following 
results  :  The  blue  injection,  or  that  which  had  been  thrown  into  the  vena  cava,  had  pen- 
etrated into  the  central  part  of  each  granule,  which  is  generally  called  the  yellow  suh 
stance  of  the  liver.  In  the  middle  of  the  central  part  was  the  yellow  injection  from  the 
hepatic  duct.  Around  tl\^  blue  injection  was  found  that  coloured  red,  which  had  been 
forced  into  the  vena  port*  and  the  hepatic  artery,  and  which  occupied  all  the  so-called 
red  substance  of  the  liver.  It  follows,  therefore,  that  each  granule  had  a  vascular  appa- 
ratus thus  arranged :  in  the  centre,  a  biliary  duct ;  farther  removed  from  the  centre,  a 
vascular  circle  formed  by  the  ramifications  of  the  hepatic  vein ;  and  external  to  this 
another  vascular  circle,  formed  by  ramifications  of  the  vena  portae  and  hepatic  artery. 
As  to  the  manner  in  which  the  vena  portae  and  hepatic  artery  are  arranged  in  relation  to 
each  other,  we  shall  find,  if  we  trace  them  into  the  substance  of  the  liver,  that  the  ram- 
ifications of  the  hepatic  artery  correspond  exactly  to  those  of  the  vena  portae  and  biliary 
duct,  which,  as  we  have  already  said,  are  all  contained  in  the  same  sheath  ;  and  that 
they  ramify  and  are  lost  upon  the  parietes  of  the  vein  and  duct,  almost  in  the  same 
manner  as  the  bronchial  arteries  are  distributed  upon  the  divisions  of  the  air  tubes.  I 
must,  therefore,  conclude  that  the  hepatic  artery  furnishes  for  the  liver  the  nutritious 
vessels  (vasa  vasorum)  of  the  vena  portae  and  hepatic  ducts  ;  and  this  will  explain  the 
disproportion  between  its  cahber  and  the  size  of  the  Uver. 

The  subdivisions  of  the  hepatic  veins,  which  follow  a  separate  course,  present  a  sim 
^ilar  peculiarity  to  that  observed  in  the  splenic  vein,  viz.,  a  multitude  of  pores  or  holes 

inter-lobular  veins.  This  appearance  is  peculiar  to  the  sub-lobular  veins,  the  canals  for  vehich  alone  are  form- 
ed by  the  bases  (c  c)  of  the  lobules.  The  portal  canals  (g,fig-  165)  are  formed  by  their  capsular  surfaces,  and 
the  openings  (d),  seen  in  the  interior  of  the  small  divisions  of  the  vena  portae,  correspond  to  the  inter-lobular 
spaces,  not  to  the  centres  of  the  lobules.  The  sub-lobular  veins  anastomose  with  each  other  (this  the  divis- 
ions of  the  vena  portae  never  do),  and  unite  to  form  the  hepatic  venous  trunks  (H,fig.  166),  into  which  no  in- 
tra-lobular  veins  open,  nor  do  tlie  bases  of  any  lobules  rest  upon  them.] 

*  [From  this  statement  the  ducts  must  be  excepted  ;  they  do  not  communicate  with  the  bloodvessels. — (See 
note,  p.  395.)]  « 

t  "  Quilibet  acinus  hepatis  e  glomeroso  constat,  vel  e  particulis  arteriE,  venae  portarum,  venie  hepaticae,  duc- 
tus biliferi  et  vasorum  absorbentium,  cujus  formam  rosie  sic  dictie  Damascenae  imaginem  pingere  nobis  licet," 
—(Corp.  Hum.  Fab.,  t.  vi.,  p.  180.)  t  See  note,  p.  395. 


THE   LIVER.  g§5 

by  which  very  small  veins  open  directly  into  them.  Their  ramifications  are  much  less 
numerous  than  those  of  the  vena  portae. 

The  result  of  the  injections  described  above  also  explains  the  difference  in  colour  be- 
tween the  centre  and  the  circumference  of  each  granule  ;  it  shows,  moreover,  that  one 
part  of  the  granule  is  impermeable  to  injections  ;  and  its  spongy  nature,  resembhng  that 
of  the  pith  of  the  rush  or  elder,  is  apparent  even  to  the  naked  eye,  in  a  section  of  a  liver 
thus  injected,  when  viewed  by  a  strong  light. 

To  resume,  then,  it  may  be  said  that  the  liver  is  composed  of  ovoid,  elliptical,  or,  rath- 
er, polyhedral  granules,  moulded  closely  upon  each  other.  Each  granule  has  its  proper 
fibrous  capsule ;  and  all  the  capsules  are  united  together  by  prolongations,  which  also 
connect  them  with  the  general  cellular  investment  of  the  liver,  and  with  that  extension 
of  it  called  the  capsule  of  GUsson.  The  granules  are  independent  of  each  other.  Each 
of  them  consists  of  a  spongy  tissue,  impermeable  to  injections  ;  of  a  biliary  duct  proceed- 
ing from  its  centre  ;  of  a  venous  network  foimed  by  the  hepatic  veins  ;  of  another  ve- 
nous network  belonging  to  the  vena  portae  ;  and  of  a  very  delicate  arterial  network  deri- 
ved from  the  hepatic  artery,  which  is  ramified  upon  the  parietes  of  the  vena  portae  and 
biliary  ducts.  Such  is  the  structure  of  the  hver.*  It  remains  for  me  now  to  examine  its 
excretory  apparatus. 

The  Excretory  Apparatus  of  the  Liver. 

The  excretory  apparatus  of  the  liver  consists  of  the  hepatic  duct,  of  the  cystic  duct, 
of  the  gall-bladder,  and  of  the  ductus  communis  choledochus. 

The  hepato-cystic  canals,  t  admitted  by  some  authors  as  constant  or  occasional  in  man, 
can  be  easily  shown  in  the  lower  animals,  but  do  not  exist  in  the  human  species. 

TTie  Hepatic  Duct. — The  hepatic  duct  arises  in  the  granules  of  the  liver  by  hepatic  radr 
KleSjt  which,  by  uniting  successively  like  veins,  constitute  small  and  then  larger  branch- 
es. These  latter  all  converge  towards  the  transverse  fissure  of  the  liver,  where  they 
terminate  ultimately  in  two  trunks  of  almost  equal  size,  which  join  each  other  at  a  very 
obtuse  angle,  and  form  the  hepatic  duct  {d,fig.  164).  The  condition  of  the  branches  of 
the  hepatic  duct  in  the  transverse  fissure  is  extremely  variable :  thus,  sometimes  the 
trunk  of  the  right  side  is  larger  than  that  of  the  left,  and  sometimes  the  opposite  is  the 
case.  Frequently  several  branches  join  the  trunks  late  in  the  transverse  fissure  ;  but, 
whatever  be  the  nature  of  these  variations,  the  right  trunk  never  corresponds  exactly  to 
the  right  lobe  of  the  liver,  nor  the  left  to  the  left  lobe. 

All  the  divisions  and  subdivisions  of  the  hepatic  duct^  are  contained  in  the  capsule  of 
Glisson,  together  with  the  ramifications  of  the  vena  portaj  and  hepatic  artery,  to  which 

*  Structure  of  the  Lobules. — [It  appears  from  the  preceding  note,  that  while  several  branches  of  the  vena 
portae  and  hepatic  artery  enter,  and  several  of  those  of  the  hepatic  duct  pass  out  at  the  capsular  surface  of 
each  lobule,  only  a  single  branch  of  the  hepatic  vein  emerges  from  its  base  ;  within  the  lobules,  the  following 
is  the  arrangement  of  these  vessels  : 

The  branches  from  the  inter-lobular  (portal)  veins  Cp  p  p,Jig.  167)  form  in  the  outer  portion  of  each  lobule 
a  venous  plexus  {I  I),  consisting  of  branches  radiating  towards  the  centre,  rv      jg~ 

connected  by  others  passing  transversely  ;   these  veins  become  capillary,  e  •      '  • 

ramify  upon  the  biliary  ducts,  and  terminating  in  the  branches  of  the  intra- 
lobular (hepatic)  vein  (h),  which  correspond  in  number  with  the  processes 

on  the  surface  of  the  lobule,  ultimately  unite  to  form  the  central  vein  that    «:;>^^^Ji^^^/^}^^'^i^'^ 
passes  out  at  its  base. 

The  lobular  arteries  are  few  in  number,  and,  according  to  Kieman,  end  in 
branches  of  the  vena  portse,  and  not  directly  in  those  of  the  hepatic  vein. 
Miiller  inclines  to  the  more  commonly  received  opinion,  that  the  three  kinds 
of  bloodvessels  communicate  with  each  other.  No  communication,  how- 
ever, exists,  as  stated  by  M.  Cruveilhier,  between  the  bloodvessels  and  the 
biliary  ducts,  which,  like  the  ducts  of  other  glands,  are  an  independent  system  of  vessels.  According  to  Mr. 
Kieman,  the  ducts  form  a  reticulated  plexus,  occupying  principally  the  outer  portion  of  each  lobule  (as  shown 
at  6  b,  jig.  168,  which  is  a  diagram  copied  from  Mr.  Kieman's  paper). 
MUUer  expresses  doubts  as  to  the  anastomosis  of  the  ducts,  and  thinks  it 
probable,  from  analogical  observation,  that  they  terminate  in  tufts  of  tubes 
having  blind  extremities. 

The  islets  formed  between  the  radiating  and  transverse  branches  of  the 
lobular  (portal)  veins  (I,  fig.  167)  correspond  to  the  acini  of  Malpighi,  and 
contain  the  biliary  ducts  with  their  capillary  bloodvessels,  and  also  a  pecu- 
liar tissue,  which  occupies  all  the  intervals  between  the  several  kinds  of 
vessels,  and  consists,  according  to  Krause,  of  hexagonal,  nucleated  cells, 
having  several  bright  points  in  them,  like  globules  of  oily  matter. 

The  appearance  of  two  substances  in  the  liver  can  now  be  explained  ;  it 
does  not  depend  on  the  biliary  ducts  being  situated  in  the  centre,  and  the  ''  '        ' 

veins  nearer  to  the  circumference  of  each  lobule  (sec  p.  391,  394),  but  in  a 
partial  congestion  of  either  the  portal  or  hepatic  system  of  veins. 

In  portal  congestion,  the  margins  of  the  lobules  are  dark,  and  their  centres  pale  ;  it  is  very  rare,  and  has 
been  seen  only  in  children. 

Of  hepatic  venous  congestion  there  are  two  stages  :  in  the  first,  the  centre  of  each  lobule  is  dark,  and  the 
margin  pale  (fig.  166)  ;  it  constitutes  passive  congestion,  and  is  the  common  state  of  the  liver  after  death  :  in 
the  second,  the  congestion  extends  to  the  portal  veins  in  the  iuter-lobular_/isiures,  but  not  to  those  in  the  inter- 
lobular spaces,  or  points  at  which  those  fissures  meet,  which  spaces  are  then  seen  to  occupy  the  centre  of  each 
pale  isolated  spot :  this  is  active  congestion  of  the  liver  ;  it  occurs  in  diseases  of  the  heart,  and  in  acute  dis- 
eases of  the  lungs  and  pleura.] 

+  [/.  c,  canals  passing  directly  from  the  liver  into  the  gall-bladder.]  t  See  note,  suprA 

<)  [Excepting  those  within  the"  lobules.] 


396  SPLANCHNOLOGY. 

they  are  connected  by  loose  cellular  tissue.  The  trunks  of  the  hepatic  duct  lie  at  the 
bottom  of  the  transverse  fissure,  and  are  hid  by  the  trunk  of  the  vena  portse  and  the 
branches  of  the  hepatic  artery.  The  hepatic  duct  {t,  fig.  169),  thus  formed  by  the  union 
of  the  two  trunks  which  occupy  the  transverse  fissure,  passes  downward  and  to  the  right 
side  for  about  an  inch  and  a  half,  and  then  unites  at  a  very  acute  angle  with  the  cystic 
duct  (s),  to  form  the  ductus  communis  choledochus  (c ;  and  x,  fig.  154).  In  this  course 
the  duct  is  contained  in  the  gastro-hepatic  omentum,  together  with  the  vena  portas,  which 
is  behind  it,  and  the  right  branch  of  the  hepatic  artery,  which  is  in  front  of  it.  A  great 
quantity  of  loose  cellular  tissue  unites  the  duct  to  these  vessels. 

The  Gail-Bladder.  Dissection. — ^A  gall-bladder  filled  with  bile  may  be  studied  without 
any  preparation  :  if  it  is  empty  it  must  be  distended,  either  with  a  fluid  or  vpith  air.  A 
beautiful  preparation  of  the  gall-bladder  may  be  made  for  preservation  by  drying  it  after 
inflation,  or  by  filling  it  with  fat,  which  is  afterward  removed  by  oil  of  turpentine. 

The  gall-bladder  {cystis  fellea,  g,fig.  164)  is  the  reservoir  of  the  bile.  It  is  situated  at 
the  lower  surface  of  the  right  lobe  of  the  liver,  occupying  a  particular  fossa  (the  fossa  of 
the  gall-bladder)  on  the  right  of  the  longitudinal  fissure,  from  which  it  is  separated  by  the 
lobulus  quadratus.  It  is  held  in  this  place  by  the  peritoneum,  which,  in  the  majority  of 
instances,  merely  passes  below  it,  but,  in  others,  almost  entirely  invests  it,  and  thus  at- 
taches it  to  the  liver  by  a  sort  of  mesentery.  In  this  latter  case  it  is  at  some  distance 
from  the  liver,  as  in  certain  animals. 

Its  fcrrm.  is  that  of  a  pear,  or  of  a  cone  with  a  rounded  base  ;  it  is  directed  obliquely, 
so  that  its  great  extremity  (g,figs.  155, 161)  looks  forward,  downward,  and  to  the  right ; 
and  its  small  extremity,  backward,  upward,  and  to  the  left  side. 

Size. — The  small  size  of  the  gall-bladder  corresponds  with  that  of  the  rest  of  the  ex- 
cretory apparatus  of  the  bile,  and  is  strongly  contrasted  with  the  great  bulk  of  the  liver. 
This  difference  becomes  still  more  striking  if  we  compare,  on  the  one  hand,  the  kidney 
with  the  liver,  and,  on  the  other,  the  urinary  bladder  with  the  gall-bladder.  It  is  true, 
however,  that  all  the  urine  must  pass  through  the  former,  while  a  part  only  of  the  bile  is 
deposited  in  the  latter. 

The  size  of  the  gall-bladder,  however,  is  subject  to  considerable  variety ;  it  sometimes 
acquires  three,  four,  or  even  ten  times  its  usual  size  from  retention  of  the  bile,  in  conse- 
quence of  obstruction  in  the  ductus  choledochus.*  Cases  have  been  recorded  in  which 
it  contained  six,  eight,  or  ten  pounds  of  bile,  but  this  I  can  scarcely  credit.  On  the  oth- 
er hand,  it  is  sometimes  closely  contracted  round  a  small  calculus,  while  the  cystic  duct 
is  completely  obliterated,  and  reduced  to  a  fibrous  cord.  It  must  undoubtedly  have  been 
such  cases  as  these  that  have  been  regarded  as  examples  of  congenital  absence  of  the 
gall-bladder. 

Relations. — In  order  to  facilitate  our  description,  we  shall  consider  the  gall-bladder  as 
consisting  of  a  body,  a  fundus,  and  a  neck. 

The  body  is  conical,  and  has  the  following  relations  :  below,  where  it  is  covered  by  the 
peritoneum,  it  is  in  relation  with  the  first  portion  of  the  duodenum,  and  the  right  extrem- 
ity of  the  arch  of  the  colon.  It  is  not  unfrequently  found  in  contact  with  the  pylorus,  or 
even  with  the  pyloric  end  of  the  stomach.  Sometimes  it  is  united  by  accidental  or  nor- 
mal adhesions  to  the  duodenum  and  arch  of  the  colon.  These  relations  account  for  the 
yellow  or  green  discoloration  which  always  takes  place  after  death  in  those  parts  of  the 
alimentary  canal  that  are  in  contact  with  the  gall-bladder ;  and  also  for  the  passage  of 
biliary  calculi  into  the  duodenum,  the  colon,  and  the  stomach.  It  is  not  very  rai-e  to  find 
the  gall-bladder  applied  by  its  whole  length  to  the  right  kidney :  this  relation  can  only 
occur  after  descent  of  the  duodenum  and  transverse  colon.  Above,  the  body  of  the  gall- 
bladder adheres  to  the  cystic  fossa  by  a  more  or  less  loose  cellular  tissue,!  and  by  ar- 
teries and  veins,  but  never  in  the  human  subject  by  biliary,  i.  e.,  hepato-cystic,  ducts. 

The  fundus  of  the  gall-bladder  {g,fig.  161),  entirely  covered  by  the  peritoneum,  gen- 
erally projects  beyond  the  anterior  margin  of  the  liver,  and  comes  into  relation  with  the 
abdominal  parietes,  opposite  the  outer  border  of  the  right  rectus  muscle,  immediately 
below  the  costal  cartilages  near  the  anterior  extremity  of  the  tenth  rib.  When  distend- 
ed with  bile  or  calculi,  the  fundus  of  the  gall-bladder  becomes  prominent,  so  as  to  raise 
the  abdominal  parietes,  through  which  it  has  been  felt  in  emaciated  individuals.  It  has 
even  been  stated  that  the  noise  made  by  the  calculi  may  be  heard  on  percussion.  This 
relation  explains  the  possibility  of  the  occurrence  of  abdominal  biliary  fistulae,  and  why 
calculi  may  escape  through  such  openings :  on  it,  also,  is  founded  the  scheme  for  ex- 
tracting the  calculi  by  an  operation  analogous  to  that  performed  for  stone  in  the  urinary 
b  adder,  and  which  I  should  not  have  mentioned  had  it  not  been  proposed  by  J.  L.  Petit. 

The  relations,  as  well  as  the  size  of  the  fundus  of  the  gaU-bladder,  present  many  vari- 

*  Anrf.her  cause  of  enlargement  of  the  gall-bladder  is  the  obstruction  of  its  neck  by  a  calculus  :  but,  in- 
stead of  bile,  it  then  contains  a  limpid  serum,  and,  in  fact,  is  converted  into  a  serous  cyst.  The  tumour  thus 
formed  may  t)e  compared  to  the  lachrymal  tumour  in  cases  of  obstruction  of  the  lachrymal  puncta  or  canals. 

t  This  cellular  tissue  may  become  inflamed,  and,  if  pus  be  formed,  it  may  pass  into  the  gall-bladder,  while 
the  bile  escapes  into  the  cellular  tissue,  and  hence  death  may  ensue.  I  have  observed,  in  a  very  short  space 
of  time,  three  examples  of  this  lesion,  which,  perhaps,  has  not  been  thoroughly  examined  ;  and  several  cases 
have  been  shown  me  under  the  name  of  gangrene  of  the  gall-bladder. 


THE   LIVER.  3g7 

eties.  The  fundus,  or  that  part  which  projects  beyond  the  Uver,  is  sometimes  as  large 
as  the  body.  I  have  seen  this  part  of  the  gall-bladder  turned  back  at  a  right  angle  upon 
its  body,  and  reaching  the  umbilicus.  It  may  be  conceived,  that  the  differences  in  the 
form  and  situation  of  the  liver  must  greatly  influence  the  situation  of  the  fundus  of  the 
gall-bladder,  which  I  have  found  in  the  hypogastrium  and  in  the  right  iliac  fossa,  either 
with  or  without  adhesion  to  the  neighbouring  parts. 

The  neck  or  apex  of  the  gall-bladder  is  twice  bent  suddenly  upon  itself,  like  an  italic  S, 
having  its  three  portions  in  contact.  It  would  appear,  in  some  cases,  that  these  two 
curves  resemble  the  thread  of  a  screw.  This  double  curvature  may  be  easily  elTaced  by 
removing  the  peritoneum  with  the  subjacent  cellular  tissue.  The  limits  between  the 
neck  and  the  body  of  the  gall-bladder  on  the  one  hand,  and  between  the  neck  and  the 
cystic  duct  on  the  other,  are  marked  externally  by  a  constriction. 

The  internal  surface  of  the  gall-bladder  is  tinged  either  green  or  yellow,  according  to 
the  colour  of  the  bile  ;  but  this  staining  is  the  effect  of  transudation  after  death  ;  its  nat- 
ural colour  is  a  whitish  gray.  Moreover,  the  internal  surface  is  irregular,  like  shagreen, 
and  has  some  crests  or  prominences  arranged  upon  it  in  polygons,  and  again  subdivided 
by  smaller  crests,  like  the  reticulum  in  the  stomach  of  ruminantia ;  so  that,  when  ex- 
amined by  a  strong  lens,  it  appears  divided  into  a  number  of  small  and  very  distinct  al- 
veoli :  some  highly-developed  papillae  or  villi,  of  a  very  irregular  shape,  are  also  found 
upon  it.  As  to  the  object  of  either  the  crests  or  the  papillae,  or  whether  they  favour  ab- 
sorption by  multiplying  the  surface,  we  are  altogether  unable  to  decide. 

Opposite  each  of  the  two  curves  of  the  S,  described  by  the  neck  of  the  gall-bladder,, 
we  find  a  very  large  valve.  The  two  valves,  which  are  in  opposite  directions,  as  well 
as  the  curves,  result  from  the  alternate  inflection  of  the  neck  itself,  and  are  efl^aced  by 
straightening  that  part.  The  portion  of  the  neck  between  the  two  valves  is  not  unfre- 
quently  dilated  into  an  ampulla.  A  calculus  is  often  formed  in  this  intermediate  portion, 
where  it  remains,  as  it  were,  encysted,  and  intercepts  the  course  of  the  bile  ;  and  that 
the  more  easily,  because  the  valves  greatly  contract  the  openings  from  the  neck  into  the 
body  of  the  bladder,  and  into  the  cystic  duct.  Moreover,  these  valves  are  opposed  nei- 
ther to  the  entrance  of  the  bile  into,  nor  to  its  exit  from,  the  bladder. 

Structure. — Proceeding  from  without  inward,  we  find  that  the  gall-bladder  is  composed 
of,  1.  A  peritoneal  coat,  which  is  reflected  from  the  lower  surface  of  the  liver  upon  the 
bladder,  completely  invests  its  fundus,  forms  a  more  or  less  incomplete  covering  for  its 
body  and  neck,  and  is  continuous  with  the  anterior  layer  of  the  gastro-hepatic  omentum. 
2.  An  areolar  fibrous  coat,  which  forms,  as  it  were,  the  framework  of  the  bladder,  and  pre- 
vents its  sudden  distension,  though  it  will  yield  to  a  long-continued  distending  force ; 
but  I  have  not  been  able  to  see  the  muscular  fibres  admitted  by  some  authors,  and  which 
can  be  so  easily  detaonstrated  in  the  larger  animals,  the  ox  in  particular.  3.  An  interned 
mucous  membrane,  the  principal  characters  of  which  I  have  noticed  when  speaking  of  the 
internal  surface  of  the  gall-bladder :  it  presents  some  folds,  which  may  be  easily  distin- 
guished from  the  borders  of  the  alveoh,  because  they  are  readily  effaced  by  distension.  Af- 
ter the  most  attentive  examination,  I  have  been  unable  to  recognise  any  crypts  or  follicles. 

The  gall-bladder  receives  one  very  considerable  artery,  the  cystic  branch  of  the  hepatic. 
The  cystic  vein  terminates  in  the  vena  portae.  The  lymphatic  vessels  are  very  numerous, 
and  easily  demonstrated ;  they  are  sometimes  tinged  by  the  colouring  matter  of  the  bile. 
Its  nerves  are  derived  from  the  hepatic  plexus. 

The  Cystic  Duct. — The  cystic  duct  {,s,fig.  169),  or  excretory  duct  for  the  bile,  is  the 
smallest  of  all  the  biliary  canals  :  it  is  not  unconunon,  however,  to  find  it  of  an  equal  or 
even  larger  size  than  the  others,  in  which  case  there  has  always  been  some  obstacle  to 
the  flow  of  the  bile  through  the  ductus  communis  choledochus  (c).  It  conm[iences  at  the 
neck  of  the  gall-bladder,  passes  downward  and  to  the  left  side  for  about  an  inch,  and 
unites  at  a  very  acute  angle  with  the  hepatic  duct  (t). 

It  is  not  straight,  but  inflected,  and,  as  it  were,  sinuous. 

Relatio-ns. — It  is  situated  in  the  substance  of  the  gastro-hepatic  omentum,  in  front  of 
the  vena  cava,  the  cystic  artery  being  on  its  left  side.  Its  internal  surface  is  remarkable 
for  its  valves,  which  are  indefinite  in  number ;  according  to  Soemmering,  there  are  from 
nine  to  twenty,  but  this  appears  to  me  to  be  an  exaggeration  :  I  have  counted  from  five 
to  twelve.  These  valves  are  concave  at  their  free  margins,  irregular,  alternate,  oblique, 
transverse,  sometimes  even  vertical,  and  united  together  by  small  oblique  valves.  In 
order  to  understand  their  structure,  a  cystic  duct  must  be  examined  under  water,  or,  rath- 
er, an  inflated  and  dried  specimen.  This  alternate  arrangement  of  the  valves  some- 
times gives  a  spiral  appearance  to  the  inner  surface  of  the  cystic  duct.*  These  valves, 
which  only  exist  in  man,  perhaps  on  account  of  the  erect  position  peculiar  to  him,  are 
not  effaced,  like  the  valves  in  the  neck  of  the  gall-bladder,  by  such  dissection  as  will  al- 
low of  straightening  of  the  duct.  Small  calculi  are  occasionally  met  with  in  the  inter- 
vals between  the  valves,  giving  to  the  cystic  duct  a  nodulated  appearance,  and  intercept- 
ing the  flow  of  the  bile.  Moreover,  the  valves  of  the  cystic  duct  are  not  more  opposed 
to  the  descent  than  to  the  ascent  of  the  bile.     It  is  even  probable  that  they  facilitate  the 

*  "  Quae  possint  aliquam  spiralis  fabricse  imagincm  ferre." — {Holler,  torn,  vi.,  liv.  xxiii.,  p.  530.) 


398  SPLANCHNOLOGY. 

ascent  of  the  bile  into  the  gall-bladder  by  supporting  the  column  of  liquid,  like  the  valves 
of  the  veins.  Perhaps  they  are  also  intended  to  retard  the  course  of  the  bile  from  the 
gall-bladder  towards  the  ductus  choledochus.  From  their  appearing  sometimes  to  have 
a  spiral  arrangement,  M.  Amussat  has  advanced  a  very  ingenious  opinion  :  that  the  as- 
cent of  the  bile  is  effected  by  a  contrivance  like  an  Archimedes'  screw.  But  an  Archi- 
medes' screw  only  causes  the  ascent  of  a  liquid  when  a  rotatory  movement  is  communi- 
cated to  it,  and  how  can  such  a  movement  be  performed  by  the  cystic  duct  1* 

The  Ductus  Communis  Choledochus. — The  ductus  communis  choledochus  ( xo^,  bile, 
doxo^,  containing ;  c,  c.  Jig.  169),  the  last  excretory  canal  of  the  bile,  seems  to  be  formed 
Fig.  169.  by  the  union  of  the  hepatic  (0  and  the  cystic 

ducts  («).  Another,  and,  perhaps,  more  simple 
manner  of  viewing  the  excretory  cansils  of  the 
liver,  would  be  to  consider  the  hepatic  duct  as 
giving  off  to  the  right,  after  a  certain  course,  the 
cystic  duct,  which,  after  passing  backward,  di- 
lates into  an  oval  ampulla  to  form  the  gall-blad- 
der ;  and  the  ductus  choledochus  as  nothing 
more  than  the  continuation  of  the  hepatic  duct. 
The  direction  of  the  ductus  choledochus  is,  in 
fact,  the  same  as  that  of  the  hepatic  duct,  i.  e., 
obliquely  downward,  a  little  to  the  right,  and 
backward :  there  is  no  line  of  demarcation  be- 
tween these  two  ducts  :  in  the  natural  state 
there  is  no  marked  difference  in  their  diame- 
ters :  the  ductus  choledochus,  when  collapsed,  is 
about  as  large  as  a  moderately-sized  goosequill. 
't  The  same  causes  give  rise  to  dilatation  of  the 

ductus  choledochus  and  of  the  hepatic  duct.  I  have  seen  the  former  as  large  as  the  duo- 
denum. {Anat.  Pathol,  avec  planches.)  Its  length  is  from  two  to  two  inches  and  a  half 
Relations. — In  the  first  part  of  its  course,  before  it  reaches  the  duodenum,  the  ductus 
choledechus  is  included  in  the  gastro-hepatic  omentum,  in  front  of  the  vena  portae,  and 
below  the  hepatic  artery,  having  the  right  gastro-epiploic  artery  along  its  left  side,  and 
surrounded  by  loose  cellular  tissue,  a  great  number  of  lymphatic  vessels,  and  several 
lymphatic  glands.  Having  reached  the  duodenum,  opposite  the  first  flexure  of  that  in- 
testine, it  passes  behind  and  to  the  inner  side  of  its  second  portion,  and  is  there  received 
into  a  groove,  or,  more  commonly,  into  a  complete  canal,  formed  for  it  by  the  pancreas. 
Lastly,  it  penetrates  very  obliquely  into  the  substance  of  the  duodenum,  about  the  mid- 
dle of  its  second  or  vertical  portion,  perforates  the  muscular  coat,  passes  between  that 
and  the  fibrous  coat,  then  between  the  fibrous  coat  and  the  mucous  membrane,  elevating 
the  latter  when  distended  with  bile  or  by  a  probe,  and  after  a  course  of  about  seven  or 
eight  lines  between  the  coats,  opens  into  the  duodenum,  about  the  lower  part  of  the  sec- 
ond portion,  at  the  summit  of  a  nipple-like  eminence  (above  c),  which  is  more  or  less 
prominent  in  different  subjects. 

In  this  third  portion  of  its  course  the  ductus  choledochus  is  in  relation  with  the  pan- 
creatic duct  (m),  which  is  situated  on  its  left.  Opposite  the  base  of  the  eminence  above- 
mentioned,  the  two  ducts  unite,  or,  rather,  the  pancreatic  duct  opens  into  the  ductus 
choledochus  ;  so  that,  at  its  termination,  the  latter  may  be  regarded  as  a  canal  having  a 
triple  origin,  viz.,  an  hepatic,  a  cystic,  and  a  pancreatict 

Internal  Surface  of  the  Ductus  Hepaticus  and  Ductus  Choledochus. — ^The  internal  surface 
of  both  the  hepatic  duct  and  the  ductus  choledochus  is  characterized  by  the  absence  of 
valves,  though  traces  of  valves  are  occasionally  met  with  in  the  ductus  choledochus ; 
by  the  absence  of  the  alveolar  structure  observed  in  the  gall-bladder  ;  and  by  having  a 
niultitude  of  openings  or  well-marked  pores,  which  are  considered  as  belonging  to  mu- 
ciparous follicles,  and  are  apparently  formed  by  an  interlacement  of  fasciculi,  having  a 
fibrous  character,  and  intersecting  each  other  at  very  acute  angles.  The  ductus  chole- 
dochus and  the  hepatic  duct  are  of  uniform  caliber  throughout  their  whole  length.  The 
ductus  choledochus  is  contracted  a  little  in  its  third  or  duodenal  portion  ;  it  dilates  into 
an  olive-shaped  ampulla,  opposite  the  base  of  the  papilla  in  the  duodenum,  and  opens  by 
an  extremely  small  orifice  or  mouth :  hence  the  reason  why  biliary  calculi  are  so  fre- 
quently arrested  in  the  ampulla  of  the  ductus  choledochus. 
From  the  narrowness  of  the  duodenal  orifice  of  the  ductus  choledochus,  from  the  mo- 

*  Another  opinion,  founded  upon  the  existence  of  the  valves,  is  that  of  Bachius,  who,  believing  that  he  had 
shown  that  the  valves  prevent  the  ascent  of  the  bile  from  the  hepatic  duct  into  the  gaU-i)ladder,  has  advanced 
very  singular  views  concerning  the  formation  and  uses  of  the  bile.  The  bile,  according  to  him,  is  formed  in 
the  gall-bladder,  and  carried  l)y  the  cystic  duct  into  the  hepatic  duct  and  the  ductus  choledochus.  By  his 
theory,  the  bile  which  reaches  the  liver  through  the  hepatic  duct  assists  greatly  in  sanguification.  This  opin- 
ion, altogether  erroneous  as  it  is,  has  perhaps  exercised  a  great  influence  in  science,  by  contributing  to  eradi- 
cate the  idea  of  the  bile  being  an  acrid,  corrosive,  and  essentially  injurious  excrementitial  fluid. 

t  Hence  the  definition  of  SoDminering  :  "  Ductus  choledochus,  id  est,  ductus  hepaticus,  cysticus,  et  pancreatir 
cus,  in  unum  conflati," — ICorpor.  Hum.  Fabric, tom.\i.,  p.  186.) 


THE    LIVER. 

▼able  or  yielding  nature  of  the  eminence  upon  which  it  opens,  and  from  the  oblique  course 
of  the  duct  through  the  substance  of  the  walls  of  the  duodenum,  it  follows  that  the  bile 
and  the  pancreatic  fluid  may  pass  freely  from  the  ductus  choledochus  into  the  duodenum, 
but  cannot  regurgitate  from  the  duodenum  into  the  duct.  On  this  subject  I  have  made 
several  experiments.  I  have  forcibly  injected  both  water  and  air  into  the  duodenum, 
included  between  two  ligatures,  but  nothing  entered  into  the  biliary  canals  :  on  the  other 
hand,  I  have  injected  the  same  fluids  from  the  gall-bladder  into  the  duodenum,  which  I 
was  thus  able  to  distend  at  pleasure.  But  then,  on  compressing  the  bowel  thus  distend- 
ed with  great  force,  I  have  never  been  able  to  cause  the  slightest  reflux  into  the  biliary 
caneils.* 

At  the  union  of  the  cystic  and  hepatic  ducts  there  is  a  very  long  spur-shaped  process, 
formed  by  the  hning  membrane  reflected  upon  itself  At  the  junction  of  the  ductus  cho- 
ledochus and  the  pancreatic  duct  there  is  also  a  similar  process,  which  I  have  seen  ex- 
tending down  to  the  duodenal  orifice.  In  neither  situation  do  these  processes  prevent 
the  fluid  of  one  canal  from  passing  into  the  other.  Thus,  the  cystic  bile  might  flow  back 
into  the  hepatic  duct,  the  pancreatic  fluid  might  regurgitate  into  the  ductus  choledochus, 
and,  on  the  other  hand,  the  bile  might  enter  the  pancreatic  duct,  if  these  canals  were  not 
habitually  full.  Moreover,  the  spur-shaped  process  between  the  ductus  choledochus  and 
the  pancreatic  canal  cannot  arrest  the  flow,  either  of  the  bile  or  the  pancreatic  fluid,  by 
being  applied  to  the  orifice  of  the  one  or  other  duct. 

Structure  of  the  Biliary  Ducts. — ^AU  the  biliary  ducts  have  a  similar  structure  :  they 
have  an  internal  mucous  membrane,  continuous  on  the  one  hand  with  the  lining  mem- 
brane of  the  gall-bladder,  and  on  the  other  with  that  of  the  duodenum  ;  it  is  thin,  and 
provided  with  slightly-developed  papillae  ;t  a.  proper  membrane,  composed  of  a  dense  are- 
olar tissue,  generally  regarded  as  fibrous,  but  which  appears  to  me  analogous  to  the  tis- 
sue of  the  dartos  condensed ;  a  cellular  layer  connecting  these  canals  to  the  surrounding 
parts  ;  and,  lastly,  the  peritoneimi,  which  forms  a  very  incomplete  accessory  tunic  for 
them. 

Thus  constituted,  the  biliary  ducts  have  very  thin  walls,  so  that  they  collapse  like 
veins,  and  are  extremely  dilatable.  In  certain  cases  of  retention  of  the  bile  we  find  the 
ductus  choledochus  and  the  hepatic  duct  as  large  as  the  duodenum,  the  divisions  of  the 
hepatic  duct  dilated  in  proportion,  and  the  tissue  of  the  liver  more  or  less  atrophied  by 
the  compression  to  which  it  has  been  subjected. 

Development  of  the  Liver. — The  development  of  the  liver  is  one  of  the  most  important 
subjects  in  its  history.     Under  this  head  we  have  several  points  to  consider  : 

1.  The  time  of  its  appearance  is  anterior  to  that  of  any  other  organ  :t  in  the  first  days 
of  intra-uterine  life  it  may  be  distinguished  by  its  colour  in  the  midst  of  the  ceUular  mass 
which  represents  the  foetus. 

2.  In  size  the  liver  is  relatively  larger  as  it  is  examined  at  an  earlier  period  of  devel- 
opment. Thus,  according  to  Walter,  in  the  embryo  of  three  weeks  it  forms  one  half  the 
weight  of  the  whole  body.  This  enormous  proportion  is  maintained  during  the  first  half 
of  intra-uterine  life.  After  this  period  its  growth  is  slower,  while  that  of  the  other  or- 
gans is  proportionally  increased,  so  that  at  birth  the  weight  of  the  liver  is  one  eighteenth 
that  of  the  whole  body.ij  After  birth  the  liver  undergoes  an  absolute  diminution  ;  some 
authors  have  even  affirmed  that  a  comparison  of  the  weight  of  the  liver  in  new-bom  in- 
fants and  in  children  of  nine  or  ten  months  old,  gives  a  difference  of  one  fourth  in  favour 
of  the  former.  It  is  generally  said  that  the  difference  in  size  affects  the  left  rather  than 
the  right  lobe  ;  but  this  has  not  appeared  evident  to  me.  Towards  the  age  of  puberty 
the  liver  has  the  same  relative  bulk  as  at  later  periods.  Attempts  have  been  made  to 
ascertain  the  proportion  between  the  weight  of  this  organ  and  that  of  the  body,  and  it 
has  been  said  that  it  forms  one  thirty-sixth  part  of  the  whole  body.  But  what  relation 
can  be  established  between  two  terms,  one  of  which,  viz.,  the  weight  of  the  body,  is 
subject  to  continual  variations  1  In  old  age  the  liver  is  smaller  than  in  the  Eidult,  a  dim- 
inution apparently  in  unison  with  that  which  occurs  in  all  the  other  organs. 

3.  The  differences  in  the  situation  of  the  liver  are  connected  with  its  variations  in  size  : 
thus,  in  the  first  half  of  intra-uterine  life,  the  liver  occupies  the  greatest  part  of  the  ab- 
domen, and  is  in  relation  with  certain  regions  in  which  it  is  not  found  at  more  advanced 
stages.  In  the  earUest  periods  it  descends  as  low  as  the  crest  of  the  ilium,  and  when 
the  abdomen  is  opened  it  presents  the  appearance  of  a  red  mass,  beneath  which  are 

*  How  can  this  fact  be  reconciled  with  another  no  less  incontestable,  viz.,  the  passage  of  lumbrici  into  the 
biliary  ducts  1  The  reason  is,  that  the  lumbricus  is  a  foreign  body,  which  has  a  power  of  selection,  and  is  able 
to  overcome  an  obstaCie,  to  seek  for  the  orifice  of  the  ductus  choledochus,  and  to  introduce  itself  within  it. 

t  [Numerous  follicles  are  found  in  the  ductus  communis  and  in  the  hepatic  duct,  and  all  its  subdivisions  ; 
according  to  Mr.  Kiernan,  even  in  the  smallest  that  can  be  examined.  In  the  larger  branches  they  are  ar- 
ranged irregularly;  in  the  smaller  ones,  in  two  longitudinal  rows,  along  opposite  sides  of  the  duct.] 

t  [In  the  embryo  of  the  bird  the  liver  is  developed  by  a  conical  protrusion  of  the  walls  of  the  intestinal  ca- 
nal into  a  granular  mass  or  blastema. — (See  Milller^s  Phys.  by  Baly,  p.  448.)  The  rudiments  of  the  cerebro- 
gpinal  axis,  of  the  heart,  and  of  the  intestinal  canal,  appear  previously  to  the  liver.] 

f)  I  have  had  occasion  to  notice,  at  the  Matemite,  the  very  great  differences  in  the  size  of  the  liver  in  in- 
fants at  birth,  for  which  I  have  been  unable  to  find  any  sufficient  reason.  There  ai'.'  some  well-formed  in 
fauts  in  whom  the  liver  at  birth  is  not  relatively  larger  than  that  of  adults 


400  SPLANCHNOLOGY. 

placed  the  other  abdominal  viscera.  During  the  second  half  of  intra-uterine  life,  and  at 
birth,  it  occupies  only  a  part  of  the  abdomen  ;  but  it  still  corresponds  to  a  considerable 
extent  of  the  abdominal  parietes  :  hence  the  ease  with  which  it  is  ruptured  by  pressure 
upon  the  abdomen  of  a  new-born  infant.  One  fact  on  record  seemed  to  me  to  prove, 
that  in  a  first  labour,  where  the  feet  presented,  the  pressure  of  the  genital  organs  of  the 
mother  was  S'ufficient  to  produce  this  result. — (Vide  Proces-verbal  de  la  Distribution  des 
Prix  de  la  Maternite,  1832.) 

In  the  eariiest  periods  the  falciform  ligament  of  the  liver  corresponds  to  the  median 
line  of  the  body  ;  at  birth  it  is  a  little  to  the  right  of  that  line,  and  is  afterward  removed 
still  farther  in  the  same  direction. 

4.  The  great  size  of  the  liver  during  intra-uterine  life  is  connected  with  the  existence 
of  the  umbilical  vein,  by  which  the  foetus  receives  the  blood  returned  from  the  placenta, 
that  is  to  say,  all  the  blood  necessary  for  its  nutrition.  The  rapid  diminution  of  the 
liver  after  birth  is  probably  owing  to  the  obliteration  of  this  vein.  It  is  a  very  remark- 
able fact,  that  the  persistence  of  this  vein  in  the  adult  is  not  accompanied  by  an  unusu- 
ally large  liver.  In  one  particular  case  of  persistence  of  the  umbilical  vein  the  liver  was 
of  a  very  small  size. — {Anat.  Path,  avec  planches,  liv.  xvii.) 

5.  The  tissue  of  the  liver  of  the  foetus  is  of  a  pale  red  colour  in  the  early  periods,  and 
of  a  deep  brown  near  the  full  term  of  pregnancy ;  its  colour  becomes  lighter  after  birth. 
The  liver  contains  a  greater  quantity  of  blood  before  than  after  birth.  Its  tissue  is  the 
less  consistent  the  earlier  the  stage  of  development  at  which  we  examine  it,  and  its  soft- 
ness is  accompanied  with  great  fragility. 

6.  The  distinction  between  what  are  called  the  two  substances  of  the  liver  is  not  ap- 
preciable during  intra-uterine  life.     It  only  becomes  apparent  after  birth. 

Functions. — The  liver  is  the  secreting  organ  of  the  bile.  The  bile  is  secreted  in  the 
glandular  granules  by  an  unknown  process.  Doubts  are  stiU  entertained  as  to  whether 
the  materials  from  which  the  secretion  is  formed  are  conveyed  by  the  hepatic  artery  or 
the  vena  portae.*  The  opinion  advanced  by  some  modern  authors,  that  the  yellow  sub- 
stance of  the  liver  is  the  only  part  concerned  in  the  secretion  of  the  bile,  and  that  the 
brown  substance  has  other  uses,  is  a  purely  gratuitous  hypothesis. 

The  bile  traverses  the  several  ramifications  of  the  hepatic  duct,  and,  having  arrived  in 
the  principal  duct,  it  may  either  enter  directly  into  the  duodenum  by  the  ductus  chole- 
dochus,  or  it  may  pass  into  the  gall-bladder  by  the  cystic  duct.  This  retrograde  move- 
ment towards  the  gall-bladder  has  much  occupied  the  attention  of  physiologists  :  perhaps 
it  may  be  explained  by  the  narrowness  of  the  duodenal  orifice  of  the  ductus  choledochus, 
by  the  elasticity  of  that  canal,  and  especially  by  the  pressure  exercised  on  its  duodenal 
portion  by  the  circular  fibres  of  the  duodenum.  The  gall-bladder  and  the  cystic  duct  are 
not  indispensable  to  the  elimination  of  the  bile.  Nothing  is  more  common  than  to  find 
the  excretory  apparatus  of  the  liver  in  old  subjects  reduced  to  the  hepatic  duct  and  the 
ductus  choledochus. 

Has  the  liver  any  other  function  besides  that  of  secreting  bile  1  The  disproportion  ex- 
isting between  the  size  of  that  organ  and  of  its  excretory  apparatus,  and  also  the  enor- 
mous bulk  of  the  liver  during  foetal  life,  i.  e.,  at  a  time  when  the  secretion  of  bile  is  at 
its  minimum  of  activity,  are  both  in  favour  of  the  opinion  that  the  liver  has  some  addi- 
tional function  ;  and  if,  again,  we  consider  that,  in  the  adult,  a  very  important  system  of 
veins  is  distributed  to  the  liver,  and  that  in  the  foetus  it  receives  the  blood  from  the  veins 
of  the  foetal  portion  of  the  placenta,  we  shall  be  led  to  presmne  that  the  unknown  func- 
tions of  this  organ  are  in  some  way  connected  with  the  process  of  sanguification. 

The  Pancreas. 

Dissection. — The  pancreas  may  be  seen  through  the  gastro-hepatic  omentum,  after 
drawing  down  the  stomach,  without  any  dissection.  In  order  to  expose  it,  turn  the 
stomach  upward  (see  fig.  154)  after  having  divided  the  two  layers  of  peritoneum  which 
proceed  from  its  greater  curvature  to  form  the  great  omentum.  It  may  also  be  ex- 
posed by  turning  the  arch  of  the  colon  upward,  and  dividing  the  inferior  layer  of  the 
transverse  mesocolon.  The  excretory  duct  is  situated  in  the  interior  of  the  organ.  In 
order  to  dissect  it,  the  glandular  substance  which  covers  it  must  be  very  carefully  re- 
moved towards  tlie  middle  and  the  right  extremity  of  the  gland.  It  may  be  injected  from 
the  ductus  choledochus,  after  the  vertical  portion  of  the  duodenum  has  been  included  be- 
tween two  ligatures  :  when  the  duodenum  is  filled  with  the  injection,  the  pancreatic  duct 
becomes  filled  in  its  turn.  It  may  also  be  injected  from  the  ductus  choledochus  after  hav- 
ing passed  a  ligature  round  the  projection  or  ampulla  which  is  common  to  the  two  ducts. 

The  -pancreas  {Trdv-Kpeag,  all  flesh)  is  a  glandular  organ  annexed  to  the  duodenum,  with 
which  it  has  immediate  relations :  it  is  situated  transversely  and  deeply  behind  the  stom- 
ach, and  in  front  of  the  lumbar  vertebrae. 

*  [From  the  researches  of  Mr.  Kiernan  (see  note  p.  395),  it  would  appear  that  the  blood  of  the  vena  ports  is 
directly  concerned  in  the  secretion  of  the  l)ile,  while  that  of  the  hepatic  artery  is  only  indirectly  concerned, 
i.  e.,  after  it  has  afforded  nutrition  to  the  tissue  and  vessels  of  the  liver,  and  has  entered  the  branches  of  the 
■'•ena  portae,  and  thus  become  portal  blood.] 


THE  PANCREAS.  401 

Form  and  Size. — In  form,  the  pancreas  resembles  no  other  gland  ;  it  is  transversely 
oblong,  flattened  from  before  backward,  large  at  its  right  extremity,  where  it  presents  a 
sort  of  angular  expansion  like  a  hammer,  and  gradually  tapering  towards  its  left  extrem- 
ity:  hence  the  division  of  this  organ  into  a  head,  body,  and  tail.  Its  long  or  transverse 
diameter  is  measured  by  the  interval  between  the  concavity  of  the  duodenmn  (e  e)  and 
the  spleen  (A).  The  size  and  weight  of  the  pancreas  present  many  varieties.  Its  weight 
is  generally  from  two  to  two  and  a  half  ounces,  but  may  reach  six  ounces.  The  pan- 
creas is  sometimes  found  atrophied,  and  in  one  case  of  this  kind  it  did  not  exceed  an 
ounce  in  weight. 

Relations. — Its  anterior  surface,  convex  and  covered  by  the  peritoneum,  is  in  relation 
with  the  stomach,  which  moves  freely  upon  it.  In  certain  cases  of  disease,  adhesion 
between  the  pancreas  and  the  stomach  takes  place,  so  that  in  chronic  ulceration  of  the 
latter  we  find  the  pancreas  supplying  the  place  of  large  portions  of  the  walls  of  the  stom- 
ach which  had  been  destroyed.  When  the  stomach  is  situated  lower  down  than  usual, 
the  pancreas  has  relations  either  with  the  liver  or  with  the  anterior  walls  of  the  abdo- 
men, from  which  it  is  separated  only  by  the  gastro-hepatic  omentum,  so  that  it  may  be 
felt  with  the  greatest  ease  through  the  abdominal  parietes.*  In  such  cases,  even  expe- 
rienced practitioners  have  not  unfrequently  been  led  to  infer  the  presence  of  scirrhus  of 
the  pylorus.  The  pancreas  is  also  in  relation,  in  front,  with  the  first  portion  of  the  duo- 
denum, and  with  the  angle  formed  by  the  ascending  and  transverse  colon. 

Its  posterior  surface  is  concave,  and  corresponds  to  the  vertebral  column,  opposite  the 
first  lumbar  vertebra ;  it  is  separated  from  the  spine,  however,  by  the  splenic  and  the 
superior  mesenteric  veins,  and  by  the  commencement  of  the  vena  portae.  The  two  last- 
mentioned  veins  are  lodged  in  a  deep  groove,  or,  rather,  almost  complete  canal,  formed  in 
the  pancreas,  which  also  includes  the  superior  mesenteric  artery  and  its  surrounding 
plexus  of  nerves.  A  great  number  of  lymphatic  vessels  and  glands,  the  pillars  of  the 
diaphragm  (d  d),  the  vena  cava  on  the  right  side,  and  the  aorta  on  the  left,  also  separate 
the  pancreas  from  the  vertebral  column.  To  the  left  of  the  spine  it  is  in  relation  vrith 
the  left  supra-renal  capsule  and  kidney,  and  the  corresponding  renal  vessels.  The  rela- 
tion of  the  pancreas  to  the  aorta  is  important ;  it  is  through  the  pancreas  that  the  pulsa- 
tions of  that  vessel  are  felt  in  the  epigastrium  in  emaciated  individuals,  and  it  is  here 
that  the  vessel  may  be  compressed. 

Its  upper  border  is  thick,  and  is  grooved  for  the  reception  of  the  splenic  artery,  which 
often  runs  in  a  sort  of  hollow  canal  formed  in  the  substance  of  the  gland  through  its  en- 
tire length.  It  also  has  relations  with  the  first  portion  of  the  duodenum  (e),  with  the 
lobulus  Spigelii,  and  with  the  coeUac  axis  (<).  The  thickness  of  this  border  has  led  some 
anatomists  to  say  that  the  pancreas  is  prismatic  and  triangular. 

Its  lower  border  is  much  tliinner  than  the  upper,  and  is  bounded  by  the  third  portion  of 
the  duodenum,  from  which  it  is  separated  on  the  left  by  the  superior  mesenteric  vessels 
{rOf  the  artery). 

Its  right,  or  duodenal,  or  great  extremity  is  in  contact  with  the  duodenum  and  the  duc- 
tus choledochus.  This  extremity  presents  a  very  remarkable  arrangement ;  it  is  curv- 
ed upon  itself  from  above  downward,  like  the  duodenum,  by  the  concavity  of  which  it  is 
circumscribed ;  then,  having  reached  the  third  portion  of  the  bowel,  it  passes  transverse- 
ly to  the  left,  behind  the  superior  mesenteric  vessels,  and  forms  the  posterior  wall  of 
the  canal  in  which  they  are  situated.  This  reflected  portion,  arranged  in  the  form  of 
a  whorl,  is  sometimes  detached  from  the  rest  of  the  gland,  on  which  account  it  has  been 
called  the  lesser  pancreas.  By  its  great  extremity  the  pancreas  is,  as  it  were,  attached 
to  the  duodenum,  beyond  which  it  projects  in  front,  but  especially  behind :  it  accompa- 
nies this  intestine  in  all  its  displacements,  so  that  when  the  duodenum  is  situated  lower 
down  than  usual,  which  happens  in  displacements  of  the  stomach  downward,  the  head 
of  the  pancreas  is  always  removed  in  the  same  direction. 

Its  left,  or  splenic,  or  small  extremity  is  narrow,  and  touches  the  spleen,  upon  which  it 
is  flattened  and  blunted,  and  sometimes  slightly  enlarged.  It  is  seen,  then,  that  in  its 
relations  to  other  parts,  the  pancreas  has  a  great  analogy  with  the  salivary  glands.  Thus, 
large  vessels  are  situated  near  and  penetrate  this  gland,  which  forms  a  sort  of  covered 
passage  for  them,  and  is  moved  by  their  pulsations.  The  diaphragm,  the  duodenum,  and 
the  stomach,  also  tend  to  disturb  and  press  upon  the  pancreas. 

Structure. — The  analogies  in  structure  between  the  pancreas  and  the  salivary  glands 
are  no  less  numerous,  and  fully  justify  the  name  of  abdominal  salivary  gland  given  to  it 
by  Siebold :  it  has  the  same  whitish  colour,  the  same  density,  t  and  the  same  arrange- 
ment into  lobes,  which  are  themselves  divisible  into  lobules.  The  identity  is  such  that 
it  would  be  impossible  to  distinguish  a  portion  of  the  pancreas  from  a  part  of  a  salivary 

*  This  condition  may  be  foretold  :  it  occurs  whenever  the  vertebral  column  can  be  felt  immediately  behind 
the  parietes  of  the  abdomen.  I  have  never  met  with  it  excepting  in  emaciated  individuals,  where  a  great 
part  of  the  small  intestine  occupied  the  cavity  of  the  pelvis.  It  is  probably  the  traction  exercised  by  the  small 
intestine  contained  in  the  pelvis  that  occasions  the  low  position  of  the  stomach. 

t  The  pancreas  sometimes  assumes  an  extreme  density,  strongly  resembling  that  of  scirrhus.  In  such  a 
case  it  is  necessary  to  make  sections  of  it,  to  be  assured  of  the  perfect  soundness  of  the  glandular  tissue.  This 
stony  hardness  generally  occurs  along  with  atrophy  of  the  organ 

Ee  E 


ii402  Sl'LANCHNOLOCfY. 

gland.  Wlicn  boiled,  they  both  have  the  same  aspect  and  the  same  taste.  There  is  no 
fibrous  capsule,  properly  so  called,  but  some  fibrous  lamellae,  which  separate  the  lobes 
and  lobules.  Cellular  tissue  is  tolerably  abundant.  Fat  is  not  uncommonly  met  with, 
either  on  the  surface  or  in  tlie  substance  of  the  pancreas  ;  I  have  even  seen  cases  of  atro- 
phy of  the  gland,  in  which  fat  appeared  to  have  been  substituted  for  the  glandular  substance. 

The  determination  of  the  structure  of  the  pancreas,  like  that  of  all  glands,  involves  two 
considerations,  viz.,  the  texture  of  each  lobule,  and  the  arrangement  of  the  vessels  and 
nerves  in  the  substance  of  the  gland.  With  regard  to  the  first  point,  I  shall  merely  re- 
fer to  what  has  been  already  stated  respecting  the  salivary  glands.*  The  arrangement 
of  the  vessels  is  perfectly  well  known. 

As  in  the  salivary  glands,  the  arteries  enter  the  pancreas  at  a  great  number  of  points. 
They  are  very  numerous  and  very  large,  considering  the  small  size  of  the  organ :  they 
arise  from  the  hepatic,  the  splenic,  and  the  superior  mesenteric.  The  principal  arterj" 
is  called  the  pancreatico-duodenalis. 

The  veins  terminate  in  the  superior  mesenteric  and  the  splenic.  The  lymphatic  vessels 
are  not  well  known ;  it  is  probable  that  they  enter  the  numerous  glands  which  are  in  the 
neighbourhood.     The  nerves  of  the  pancreas  are  derived  from  the  solar  plexus. 

The  excretory  duct  {u,fig.  169)  is  called  the  canal  of  Wirsung,  from  the  name  of  its  dis- 
coverer, a  young  anatomist,  who  was  too  soon  lost  to  science.  By  an  arrangement,  of 
which  we  have  no  other  example  in  the  body,  this  excretory  duct  is  contained  entirely 
in  the  substance,  we  might  even  say,  in  the  centre  of  the  gland  ;  so  that,  in  order  to  ex- 
pose it,  the  superficial  portion  of  the  organ  must  be  carefully  divided.  It  is  generally 
single,  but  sometimes  double,  and  then  there  is  a  principal  duct  belonging  to  the  body  of 
the  pancreas,  and  a  small  duct  for  the  reflected  portion,  or  lesser  pancreas.  The  pan- 
creatic duct  measures  the  entire  length  of  the  gland  ;  it  is  narrow  at  the  splenic  extrem- 
ity, which  may  be  regarded  as  its  origin,  and  gradually  increases  in  size  as  it  approach- 
es the  duodenal  extremity ;  there  it  bends  downward,  to  reach  the  ductus  choledochus, 
to  the  left  of  which  it  is  placed  ;  it  runs  along  the  side  of  that  duct,  then  perforates  it  ob- 
liquely, and  opens,  as  I  have  already  described  when  speaking  of  the  liver,  in  the  olive- 
shaped  ampulla  immediately  preceding  the  duodenal  orifice  of  the  ductus  choledochus. 
It  follows,  therefore,  that  the  pancreatic  duct  and  the  ductus  choledochus  open  by  a  com- 
mon orifice  in  the  human  subject.  This  arrangement  is  constant,  and,  when  we  find  a 
pancreatic  duct  perforating  the  duodenum  separately,  we  may  be  certain  that  there  is 
another  duct  presenting  the  regular  arrangement ;  at  least,  I  have  never  observed  to  the 
contrary.  As  to  the  precise  situation  of  the  separate  opening  of  the  supernumerary  pan- 
creatic duct,  it  may  be  either  in  front  of,  behind,  below,  or  above,  the  orifice  of  the  duc- 
tus choledochus.  Tiedemann,  who  has  collected  all  the  known  cases  of  double  pancre- 
atic duct,  and  all  the  varieties  of  insertion  found  in  the  human  subject,  has  arrived  at  the 
curious  result,  that  these  varieties  have  their  analogies  in  the  different  species  of  animals. 

The  mode  in  which  the  divisions  of  the  pancreatic  duct  are  inserted  into  the  principal 
trunk  deserves  to  be  noticed.  The  ultimate  ducts  of  the  pancreas  do  not,  in  fact,  unite 
into  larger  and  larger  branches,  like  the  veins,  but  the  small  branches  coming  from  each 
lobule  cpen  directly,  and  in  succession,  into  the  general  duct :  an  arrangement  which 
gives  to  the  excretory  apparatus  of  the  pancreas  the  appearance  of  those  insects  called 
centipedes. 

As  to  the  structure  of  the  pancreatic  duct,  its  walls  are  very  thin ;  it  is  collapsed,  and 
of  a  milk-white  colour,  very  distinct  from  the  grayish- white  hue  of  the  proper  tissue  of 
the  gland.  Its  internal  surface  is  extremely  smooth,  like  a  serous  membrane  ;  t  its  thin- 
ness renders  the  determination  of  its  texture  very  difficult ;  it  is  very  extensible. 

Development. — The  development  of  the  pancreas  presents  no  peculiarities  excepting 
such  as  relate  to  its  size,  which  is  relatively  greater  in  the  foetus  and  the  new-born  in- 
fant than  in  the  adult.  Examples  have  occurred  of  disease  of  the  pancreas  during  intra- 
uterine life  ;  and  I  have  found  a  scirrhous  pancreas  in  a  foetus  at  the  full  term. 

Function. — The  pancreas  is  the  secreting  organ  of  a  particular  fluid  called  the  pancre- 
atic fluid,  the  physical  and  chemical  characters  of  which  have  not  been  well  known  until 
very  lately.  I  have  met  with  two  cases  of  retention  of  the  pancreatic  fluid.  The  dila- 
ted canal  resembled  a  transparent  serous  cyst ;  the  contained  liquid  was  extremely  vis- 
cid and  transparent,  but  of  a  whitish  hue,  like  a  solution  of  gum-arabic  ;  it  had  a  slight- 
ly saline  taste  ;  the  collateral  ducts  were  extremely  dilated.  There  were  some  white 
patches,  resembling  plaster,  in  the  centre  of  many  of  the  lobules.  This  substance  was 
more  abundant  in  some  of  the  lobules,  and,  when  removed,  presented  the  appearance  of 
small  lumps  of  plaster  or  chalk.  The  pancreatic  fluid  submitted  to  chemical  analysis  by 
M.  Barruel  proved  to  be  an  extremely  pure  mucus.  M.  Barruel  even  stated  to  me  that 
it  was  the  purest  mucus  he  had  ever  examined.    It  possesses  in  the  highest  degree  the 

*  [The  only  obsen'able  difference  between  the  lobules  of  the  pancreas  and  salivary  glands  is,  that  the  closed 
tenninatiou  of  the  ducts  are  cylindrical  in  the  former,  and  slightly  dilated  in  the  latter  (see  note,  p.  341).] 

t  lit  is  a  mucous  membrane,  continuous  with  that  of  the  duodenum,  and  covered  with  epithelium.  In  some 
subjects,  Mr.  Kiernan  found  mucous  follicles  in  it,  similar  to  those  in  tlie  biliary  ducts  ;  in  others,  no  traces  of 
them  could  be  discovered.     None  were  seen  in  the  salivary  ducts.] 


THE    SPLEEN.  460 

property  of  rendering  water  viscyi,  either  by  dissolving,  or  by  being  diffused  in  it.  This 
mucus  contains  free  soda,  a  trace  of  chloride  of  sodium,  and  a  very  slight  trace  of  phos- 
phate of  lime.  There  is,  therefore,  an  analogy  belvi^een  the  pancreatic  and  salivary  fluids, 
as  the  anatomical  investigation  of  these  glands  had  previously  led  us  to  suppose.* 

The  Spleen. 

The  spleen  {aizTiriv,  lien ;  k,fig.  154)  is  a  spongy  and  vascular  organ,  the  functions  of 
which,  though  little  known,  appear  to  be  connected  with  those  of  the  abdominal  venous 
system. 

It  is  deeply  situated  {k,figs.  155,  161)  in  the  left  hypochondrium,  behind  and  to  the 
left  of  the  great  end  of  the  stomach,  to  which  it  is  united  by  a  fold  of  peritoneum,  called 
the  gastro-splenic  omentum.  It  is  also  retained  in  its  place  by  the  peritoneum,  which  is 
reflected  upon  it  from  the  diaphragm,!  and  by  the  vessels  which  enter  and  pass  out  from 
it.  Being  suspended  rather  than  fixed  to  certain  movable  parts,  the  spleen  necessarily 
participates  in  their  movements ;  and  the  contraction  or  relaxation  of  the  diaphragm,  as 
well  as  the  alternate  distension  and  collapse  of  the  stomach,  exert  an  undoubted  influ- 
ence upon  it ;  but  these  slight  and  temporary  changes  of  position  do  not  constitute  a 
true  displacement. 

It  may  even  be  said  that  displacements  of  the  spleen,  which  are  very  rare,  are  almost 
always  congenital.  Thus,  Haller  has  seen  this  organ  situated  at  the  left  side  of  the 
bladder,  in  an  infant  one  year  old ;  Desault  has  found  it  in  the  right  cavity  of  the  thorax 
in  a  foetus  at  the  full  time.  I  do  not  here  allude  to  cases  of  complete  transposition  of 
the  viscera,  nor  to  cases  where  the  change  of  situation  depends  on  enlargement  of  the 
spleen,  or  on  displacement  of  the  stomach,  t  I  have  mentioned  elsewhere  that  I  have 
found  the  spleen  in  the  umbilical  region. 

Accidental  adhesions  of  the  spleen  are  so  frequent  that  they  deserve  to  be  mentioned. 
They  are  sometimes  filamentous,  and  sometimes  cellular,  and  they  render  painful  the 
slightest  changes  of  position  in  this  organ,  from  violent  contractions  of  the  diaphragm, 
or  from  great  distension  of  the  stomach :  these  adhesions  are  almost  always  the  sequelae 
of  intermittent  fevers. 

Number. — ^The  spleen  is  single  in  the  human  subject.  The  supernumerary  spleens  oc- 
casionally met  with  near  it  are  nothing  more  than  small  ovoid  or  spheroidal  fragments 
of  the  spleen,  which  at  first  sight  might  be  taken  for  lymphatic  glands.  I  have  never 
seen  more  than  two  supernumerary  spleens  in  man.  It  is  said  that  they  are  more  fre- 
quent in  the  fcetus  than  in  the  adult :  this  opinion  is  erroneous. §  It  has  been  said  that 
ten,  twelve,  and  even  twenty-three  supernumerary  spleens  have  been  observed.  With- 
out denying  the  possibility  of  the  fact,  I  am  inclined  to  doubt  its  occurrence.  As  the 
spleen  is  always  multiple  in  a  great  number  of  animals,  supernumerary  spleens  in  man 
may  be  regarded  as  the  last  trace  of  such  an  arrangement. 

With  regard  to  the  examples  of  congenital  or  accidental  absence  of  the  spleen  men- 
tioned by  some  authors,  it  should  be  remarked,  that  they  were  accompanied  with  se- 
rious diseases  of  the  abdomen,  and  that  small  adherent  spleens,  lost  in  some  measure 
among  the  surrounding  organs,  may  easily  have  escaped  notice  in  a  not  very  close  ex- 
amination. 

Size  and  Weight. — There  is  no  organ  which  varies  more  than  the  spleen  in  regard  to 
size  and  weight.    These  differences  may  be  referred  to  the  following  heads  : 

Individual  Differences. — It  is  in  vain  to  attempt  to  establish  a  relation  between  the 
size  of  the  spleen  and  that  of  the  liver,  or  between  the  size  of  the  spleen  and  the  stature, 
weight,  constitution,  and  habits  of  the  individual.il 

Differences  from  Physiological  Conditions. — The  spleen  is  often  found  small,  wrinkled, 
shrunk,  or,  as  it  were,  withered  and  collapsed ;  a  state  that  certainly  supposes  the  op- 
posite condition  of  distension.  In  other  cases  the  spleen  is  large,  and  looks  as  if  it 
were  stretched.     Ought  we,  then,  to  admit,  with  Lieutaud,1F  that  the  pressure  from  the 

*  [According  to  the  best  analyses,  the  pancreatic  fluid  differs  from  saliva  in  containinsr  a  greater  amount 
of  solid  matter,  and  also  in  the  character  of  its  constituents  :  saliva  is  usually  alkaline,  and,  besides  other  sub- 
stances, contains  salivine,  mucus,  and  sidpho-cyanate  of  potassa  ;  the  pancreatic  fluid  contains  albumen,  ca- 
sein, but  little  salivine  and  mucus,  and  no  sulpho-cyanate  ;  in  other  respects  the  two  fluids  agree.] 

t  [This  reflection  is  called  the  ligamentum  phrenico-lienale.  The  spleen  is  also  connected  by  the  peritic 
Ileum  to  the  arch  of  the  colon.] 

i  The  great  end  of  the  stomach  is  the  most  fixed  part  of  that  viscus,  on  account  of  its  connexion  with  the 
CBSophagus.  Changes  of  position  in  this  organ  affect  partly  the  portion  between  the  pylorus  and  the  cardia, 
and  partly  the  pylorus  itself. 

()  It  is  true  that  a  greater  number  of  cases  of  supernumerary  spleens  in  the  fcetus  have  been  recorded  than 
in  adults;  but  the  fact  is  easily  explained,  if  we  consider  that  in  the  fcetus  supernumerary  spleens  cannot 
escape  notice,  while  they  are  often  diflicult  to  be  seen  in  the  adult,  on  account  of  the  fat  with  whicli  the 
omenta  are  loaded. 

II  The  spleen  is  proportionally  larger  in  man  than  in  the  lower  animals.  It  has  been  said,  as  if  it  were  pos- 
sible to  establish  a  relation  between  two  such  variable  terms  as  the  weight  of  the  spleen  and  the  body,  that 
the  former  is  i^^  th  of  the  latter. 

%  Lieutaudasserts  that  he  has  constantly  found  the  spleen  larger  when  death  has  occurred  while  digestion 
was  going  on  in  the  stomach  than  when  it  has  happened  after  that  process  had  been  completed ;  but  the 
spleen  varies  so  much  in  size  that  we  cannot  compare  the  spleen  of  one  subject  with  that  of  another.  An  in- 
genious experiment  has  been  made,  the  re.sult  of  which  is  opposed  to  Lieutaud's  opinion  :  out  of  four  newly- 


404  SPLANCHNOLOGY. 

distended  state  of  the  stomach  during  digestion  diminishes  the  size  of  the  spleen,  which, 
on  the  other  hand,  becomes  the  seat  of  an  afflux  of  blood  in  the  intervals  between  the 
occurrence  of  that  process.  This  idea  is,  perhaps,  erroneous  as  far  as  regards  the  pe- 
riods of  collapse  and  turgescence  ;  but  it  is  correct  as  to  the  principal  fact,  viz.,  the  al- 
ternation of  those  two  opposite  conditions. 

Differences  from  Age. — The  spleen  is  proportionally  smaller  in  the  foetus  than  in  the 
adult,  and  in  the  adult  than  in  the  aged. 

Differetices  from  Disease. — The  morbid  differences  in  the  size  of  the  spleen  suggest 
most  important  considerations.  In  a  great  number  of  patients  suffering  with  intermit 
tent  fevers,  more  especially  when  this  organ  is  already  enlarged  from  previous  attacks, 
it  is  manifestly  swollen  during  each  access.  Hypertrophy  of  the  spleen  may  proceed  to 
an  extraordinary  extent ;  so  that  this  organ,  which,  in  the  natural  condition,  is  with- 
drawn so  deeply  into  the  left  hypochondrium  as  not  to  be  seen  on  opening  the  abdomen, 
in  certain  cases  fills  almost  the  whole  of  the  abdominal  cavity  ;  while  its  weight,  which 
varies  from  two  to  eight  ounces  in  the  healthy  condition,  may  be  as  much  as  ten,  twen- 
ty, or  thirty  pounds ;  one  case,  indeed,  has  been  recorded  where  the  spleen  weighed 
forty-three  pounds. 

Atrophy  of  the  spleen  is  very  rare.  I  have  seen  it  reduced  to  the  weight  of  two 
drachms. 

The  specific  gravity  of  the  spleen  is,  to  that  of  water,  as  1160  to  1000. 

The  spleen,  both  upon  the  surface  and  in  the  interior,  most  commonly  resembles  in 
colour  the  dark  lees  of  wine.  This  colour,  however,  presents  many  varieties  from  a 
deep-brown  red  to  a  pale  gray.  When  the  surface  has  been  some  time  exposed  to  the 
air,  it  becomes  bright  red,  like  the  surface  of  venous  blood  soon  after  its  abstraction. 
Age,  the  kind  of  death,  and  diseases,  have  much  effect  on  the  colour  of  this  organ,  the 
different  parts  of  which  are  not  always  of  a  uniform  tint.  I  have  seen  a  spleen  of  a 
deep  chestnut-brown  hue. 

Consistence. — One  character  of  the  tissue  of  the  spleen  is  its  extreme  friability.  In 
general  it  may  be  lacerated  by  the  pressure  of  the  finger,  to  which  it  communicates  a 
feeling  of  crepitation,  and  emits  a  sound  like  the  crackling  produced  by  bending  tin. 
The  spleen  may  be  regarded  as  the  most  friable  of  all  organs  excepting  the  brain.  Thus, 
examples  have  been  recorded  of  its  laceration  from  blows,  or  falls  upon  the  abdomen, 
and  even  from  a  general  concussion,  or  from  the  contraction  of  the  diaphragm  and  ab- 
dominal muscles  during  violent  exertion,  &c. 

The  consistence  of  the  spleen  also  varies  much  in  different  individuals,  and  in  dis- 
eases ;  indeed,  the  most  important  alterations  of  this  organ  may  be  referred  to  either 
increased  or  diminished  consistence.  In  induration,  which  is  generally  accompanied 
with  hypertrophy,  the  tissue  of  the  spleen  is  compact,  brittle,  and  dry,  and  breaks  like  a 
piece  of  compact  resin.  In  softening,  carried  to  its  highest  degree,  the  spleen  is  con- 
verted into  an  inorganic  pulp,  exactly  resembling  a  healthy  spleen  broken  down  by  the 
fingers,  and  containing  a  greater  quantity  of  fluid  than  natural.  This  state  is  often  ob- 
served after  malignant  fevers,*  and  when  the  membranes  are  torn,  the  substance  of  the 
spleen  escapes  spontaneously. 

Figure. — The  spleen  has  a  crescentic  form  ;  its  long  diameter  is  vertical,  its  concavity 
directed  to  the  right,  and  its  convexity  to  the  left  side.  It  may  be  compared,  as  was 
done  by  Haller,  to  a  segment  of  an  ellipse  cut  longitudinally. 

It  presents  for  consideration  an  external  and  an  internal  surface,  and  a  circumference. 

The  external  or  costal  surface  is  convex,  smooth,  and  in  relation  with  the  diaphragm, 
which  separates  it  from  the  ninth,  tenth,  and  eleventh  ribs  ;t  hence  arises  the  influence 
of  contractions  of  the  diaphragm  upon  the  spleen,  and  the  possibility  of  its  being  rup- 
tured during  a  violent  effort.  This  relation  also  accounts  for  tlie  pain  felt  in  the  region 
of  the  spleen  after  quick  running,  and  the  difficulty  and  pain  attendant  on  a  strong  inspi- 
ration made  while  running  by  persons  in  whom  the  spleen  is  hypertrophied. 

We  frequently  find  a  prolongation  of  the  liver  almost  completely  covering  the  external 
surface  of  the  spleen. 

The  internal  or  gastric  surface  is  concave  in  all  directions,  and  presents,  at  the  junc- 
tion of  the  two  anterior  thirds  with  the  posterior,  a  somewhat  irregular  series  of  open- 
ings, which  are  themselves  irregular  in  form  and  number,  are  situated  at  greater  or  less 
intervals,  and  arranged  longitudinally.  This  row  of  openings  is  called  XYve  fissure,  or  hi- 
lus  {h,fig.  154)  of  the  spleen.  The  gastro-splenic  omentum  is  attached  near  this  fissure. 
Some  varieties  are  observed  in  the  arrangement  of  the  internal  surface  of  the  spleen. 
Thus,  it  sometimes  presents  a  uniform  concavity,  and  sometimes  there  is  a  sort  of 
projecting  ridge  opposite  the  hilus,  which  divides  it  into  two  unequal  parts,  one  anterior 

bom  puppies,  belonging  to  the  same  litter,  two  were  kept  witbout  food,  while  to  the  other  two  milk  was 
given  ;  on  killing  them,  their  spleens  were  all  found  of  the  same  size. 

*  Vide  Anat.  Path,  avec  Planches,  liv.  ii.,  art.  Maladies  de  la  Rate.  I  have  been  able  to  collect  tho 
splenic  fluid  in  a  medicine  vial,  and  to  submit  it  to  different  experiments. 

t  It  is  said  that  the  ribs  produce  marks  upon  the  spleen  from  the  pressure  exercised  by  them  upon  it  during 
life.  1  have  never  observed  this  appearance,  and  can  only  conceive  it  to  exist  in  cases  of  hypertrophy  of  the 
spleen. 


THE   SPLEEN.  405 

and  larger,  the  other  posterior  and  smaller :  in  the  latter  case,  which  is  common,  the 
spleen  is  of  a  prismatic  and  triangular  form. 

The  following  are  the  relations  of  the  internal  surface  :  the  part  situated  in  front  of 
the  hilus  has  relations  with  the  great  cul-de-sac  of  the  stomach,  and,  on  the  right  and 
behind  this  cul-de-sac,  with  the  gastro-splenic  omentum  and  the  vasa  brevia  situated 
within  it :  the  left  extremity  of  the  liver,  which,  as  we  have  seen  occasionally,  covers 
the  external  surface  of  the  spleen,  is  more  frequently  in  relation  with  the  internal  sur- 
face of  that  organ.  Behind  the  hilus  the  spleen  corresponds  with  the  left  kidney,  supra 
renal  capsule,  and  pillar  of  the  diaphragm,  which  separate  it  from  the  spine,  and  with  the 
small  extremity  of  the  pancreas. 

The  circumferenc  is  elliptical ;  its  posterior  border  is  thicker  above  than  below,  and  is 
in  relation  with  the  kidney,  which  it  sometimes  covers  through  its  entire  length ;  its  an- 
terior border  is  thinner,  and  is  applied  to  the  stomach  ;  its  upper  extremity  is  thick,  often 
bent  upon  itself,  and  in  contact  with  the  diaphragm,  from  which,  however,  it  is  occasion- 
ally separated  by  the  liver ;  its  inferior  extremity  is  pointed,  and  rests  upon  the  angle 
formed  by  the  transverse  and  descending  colon,  or  upon  the  portion  of  transverse  meso- 
colon which  supports  that  angle.  The  circumference  of  the  spleen  is  notched,  and 
sometimes  marked  more  or  less  deeply  by  fissures,  which  are  prolonged  upon  both  its 
surfaces,  particularly  upon  the  external  surface,  and  which  divide  it  into  a  greater  or  less 
number  of  distinct  lobules.  This  lobular  arrangement  is  the  last  indication  of  the  mul- 
tiple spleens,  of  which  we  have  already  spoken.  The  description  of  the  relations  just 
given  applies  when  the  stomach  is  empty  ;  when  that  viscus  is  distended,  they  are  some- 
what different.  The  spleen,  which  before  was  separated  from  the  stomach  by  the  gas- 
tro-splenic omentum,  is  then  applied  directly  to  it,  and  is  moulded  upon  it,  so,  as  it  were, 
to  cover  its  walls.  It  has  no  longer  any  relations  with  the  kidney  and  the  vertebral  column, 
but  is  situated  below  and  behind  the  great  cul-de-sac  of  the  stomach,  and  not  to  the  left 
of  it ;  and  it  becomes  horizontal  instead  of  being  vertical,  as  when  the  stomach  is  empty. 

Structure. — Besides  two  investing  membranes,  one  serous,  the  other  fibrous,*  the 
spleen  consists  of  cells  having  fibrous  parietes,  and  filled  with  a  grumous  fluid,t  of  the 
colour  of  port  wine  dregs,  of  certain  corpuscules  not  very  distinct  in  the  hirnian  subject, 
of  a  very  large  artery  and  still  larger  vein,  and  of  lymphatic  vessels  and  nerves. 

The  serous  or  peritoneal  coat  invests  the  whole  spleen,  with  the  exception  of  the  hilus, 
which  corresponds  to  the  gastro-splenic  omentum.  It  gives  a  smooth  appearance  to  the 
spleen,  lubricates  its  surface,  and,  at  the  same  time,  fixes  it  to  the  neighbouring  parts  by 
the  bands  which  it  forms.    Its  internal  surface  adheres  closely  to  the  fibrous  membrane. 

The  proper  coat  of  the  spleen  forms  a  sort  of  fibrous  shell,  which  is  strong,  notwith- 
standing its  tenuity  and  transparency.  This  membrane  is  the  seat  of  those  cartilaginous 
plates  which  are  so  often  found  upon  its  surface,  and  which  conceal  its  true  colour.  It 
is  intimately  united  to  the  peritoneal  membrane  by  its  outer  surface,  and  adheres  still 
more  closely  by  its  inner  surface  to  the  tissue  of  the  spleen  by  means  of  exceedingly  nu- 
merous and  dense  fibrous  prolongations,  which  penetrate  it  in  all  directions,  and  inter- 
lace in  every  way,  so  as  to  form  areolae  or  cells,  the  arrangement  of  which  \fre  shall  here- 
after examine.  Farther,  the  proper  coat  is  not  perforated  at  the  hilus  for  the  passage  of 
the  vessels,  but  by  an  arrangement  similar  to  that  already  noticed  in  the  liver,  it  is  re- 
flected around  the  vessels  opposite  the  hilus,  like  the  capsule  of  Glisson,  and  is  prolong- 
ed upon  both  the  arteries  and  veins,  forming  sheaths  which  divide  and  subdivide  like  the 
vessels  themselves,  and  receive  the  prolongations  given  off"  from  the  inner  surface  of  the 
proper  coat. 

This  arrangement  has  been  very  well  described  by  Delasonne  {Mim.  Acad,  des  Scien- 
ces, 1754),  and  especially  by  Dupuytren  (Thise  de  M.  Assolant).  It  follows,  therefore, 
that  the  basis  of  the  spleen  is  composed  of  a  fibrous  structure,  consisting  of  an  investing 
fibrous  membrane,  of  fibrous  sheaths  which  accompany  the  vessels  in  their  divisions  and 
subdivisions,  even  to  their  terminations,  and  of  prolongations  arising  from  the  inner  sur- 
face of  the  membrane,  interlacing  in  all  directions,  and  attached  to  the  outer  surface  of 
the  sheaths.J 

The  internal  framework  of  the  spleen  is  therefore  an  areolar  tissue,  which  may  be 
very  well  displayed  by  washing  away  the  pulpy  matter  of  this  viscus  by  means  of  a  stream 
of  water ;  there  will  then  remain  a  whitish  areolar  and  spongy  tissue.  This  is  also  very 
clearly  shown  by  injecting  it  either  with  mercury  or  some  coloured  liquid,  or  even  by  in- 
flating it  with  air  blown  through  a  puncture.  The  coats  are  then  raised  in  different  pla- 
ces, and  after  desiccation,  the  areolar  structure  becomes  evident.  This  experiment  also 
shows  that  the  spleen  is  divided  into  a  number  of  compartments,  for,  without  rupture, 
only  a  small  portion  of  the  organ  can  be  injected  in  this  way. 

It  appears,  then,  that  the  proper  tissue  of  the  spleen  is  composed  of  an  areolar  fibrous 

*  See  note,  infra.  t  See  Bote,  p.  406. 

t  [This  basis  or  framework  is  more  or  less  developed  in  the  different  species  of  animals  :  it  is  much  stronger 
in  the  horse  than  in  the  ox.  The  proper  coat  of  the  spleen,  together  with  the  sheaths  for  the  vessels,  and  the 
prolongations  or  trabcculae  given  off  from  it,  are  highly  elastic,  and  are  generally  »tated  to  consist  of  yellow 
elastic  tissue,  not  of  ordinary  fibrous  tissue.] 


^6  SPLAI^dHNOLOGY. 

network,  and  of  a  pultaeeous  matter,  gf  the  colour  of  port  wine  lees — ^the  splenic  juice  or 
matter,  regarded  by  the  anciepts  as  one  of  the  fundamental  humours  of  the  body,  called 
atra  bills,  and  which  modern  Aemists  have  not  yet  sufficiently  examined. 

We  have  now  to  determine  the  arrangement  of  the  cells,  and  the  relation  between 
these  cells  and  the  arteries,  veins,  and  nerves. 

The  Splenic  Artery. — No  organ  of  so  small  a  size  receives  so  large  an  artery.  The 
splenic  artery  is,  in  fact,  the  largest  branch  of  the  cceliac  axis,  and,  on  this  account,  rup- 
tures or  wounds  of  the  spleen  are  almost  always  followed  by  fatal  hemorrhage.  It  is 
also  remarkable  for  its  tortuous  course  ;  when  reduced  to  half  its  original  size,  from  hav- 
ing given  off  several  branches,  it  enters  the  spleen  by  four  or  five  branches  at  greater  or 
less  distances  from  each  other.  These  branches  divide  in  the  usual  manner  in  the  sub- 
stance of  the  organ,  and  preserve  their  tortuous  character  even  to  their  terminations. 
One  peculiarity  well  worthy  of  attention  is,  that  the  arteries  constantly  divide  in  a  ra- 
diating manner,  so  that  air,  or  water,  or  tallow,  thrown  into  one  arterial  division,  does 
not  pass  into  the  branches  of  the  others.  This  mode  of  division  is  observed  not  only  in 
the  larger,  but  also  in  the  smaller  arteries,*  so  that  the  spleen  may  be  considered  as  an 
aggregate  of  a  considerable  number  of  small  spleens,  united  together  by  a  common  in- 
vestment ;  and  accordingly,  if  in  a  living  animal  one  division  of  the  splenic  artery  be  tied, 
the  portion  of  the  spleen  to  which  it  is  distributed  becomes  blighted,  while  the  rest  re- 
mains in  the  natural  state.  This  arrangement  of  the  arteries  may  be  shown  in  a  very 
striking  manner  by  injecting  their  several  divisions  with  differently-coloured  substances. 
The  injected  matters  will  not  mix,  and  the  line  of  demarcation  between  the  lobes  will 
become  evident. 

This  structure  explains  how  multiple  spleens  may  occur  in  man  and  the  lower  animals, 
and  why  there  are  so  many  varieties  in  this  respect  in  the  animal  series. 

Some  branches  from  the  splenic,  lumbar,  and  spermatic  arteries  enter  the  spleen 
through  the  folds  of  the  peritoneum. 

The  splenic  vein  is  four  or  five  times  larger  than  the  artery :  it  forms  one  of  the  prin- 
cipal roots  of  the  vena  portae,  and  is  almost  equal  to  the  other  root  formed  by  the  supe- 
rior mesenteric  vein.  The  venous  communication  between  the  spleen  and  the  liver  has, 
in  a  great  measure,  given  rise  to  the  opinion  that  they  are  connected  in  function.  The 
spleen  is  filled  by  the  numberless  and  large  divisions  of  this  vein ;  it  might  even  be  said 
that  the  texture  of  the  spleen  is  essentially  venous,  that  it  is  composed  of  a  venous 
plexus  or  an  erectile  tissue,  and  that  it  bears  the  same  relation  to  the  veins  that  the 
lymphatic  glands  do  to  the  lymphatic  vessels.  All  the  splenic  cells  communicate  with 
the  veins,  or,  rather,  they  are  nothing  more  than  these  veins  themselves,  supported  by  the 
fibrous  columns  and  sheaths  already  described :  this  is  shown  by  the  following  consider- 
ations and  experiments : 

1.  If,  according  to  the  example  of  Delasonne,t  we  examine  the  spleen  of  the  ox  by  lay- 
ing open  the  splenic  veins  and  their  divisions  by  means  of  a  grooved  director,  we  shall 
find  that  these  veins  are  almost  immediately  reduced  to  their  lining  membrane,  and  per- 
forated with  very  distinctly  formed  foramina,  through  which  the  dark  reddish-brown  sple- 
nic matter  is  visible.  These  foramina  soon  become  so  numerous,  that  the  veins  are  con- 
verted into  cavities  or  cells,  the  walls  of  which  are  perforated  with  openings  of  various 
sizes,  filled  with  the  splenic  pulp.  This  arrangement,  which  is  most  manifest  under 
water,  proves  that  the  tissue  of  the  spleen  is  composed  of  venous  cells,t  like  the  corpo- 
ra cavernosa  of  the  penis.  In  man,  the  horse,  and  the  dog,  the  great  veins  are  not  per- 
forated with  foramina,  but  the  cellular  and  areolar  arrangement  of  the  splenic  v^ins,  at 
a  certain  depth,  is  not  less  manifest. 

2.  If  we  inject  the  splenic  artery,  the  spleen  will  become  very  slightly  increased  in 
bulk  at  first,  i.  c,  as  long  as  the  injected  matter  does  not  pass  into  the  venous  system  ; 
but  as  soon  as  this  occurs,  and  it  does  so  readily,  the  increase  in  size  becomes  rapid :  it 
follows,  therefore,  that  the  communication  between  the  artery  and  the  splenic  cells  is 
indirect."^  On  the  other  hand,  if  we  inject  the  vein,  the  cells  are  immediately  dilated, 
and  the  spleen  becomes  prodigiously  increased  in  bulk :  it  is  easy  to  perceive  that  the 
communication  is  direct,  and  that  the  venous  system,  in  some  measure,  forms  the  basis 
of  this  organ. 

We  can  very  seldom  meet  with  a  human  spleen  sufl5ciently  healthy  for  the  following 
experiment.  It  will  succeed  perfectly  with  the  spleen  of  a  horse,  which  is  of  a  much 
denser  structure.  The  spleen  ought,  in  the  first  place,  to  be  freed  from  the  liquid  which 
it  contains  ;  this  must  be  accomplished  by  forcing  water  into  the  splenic  artery.     The 

*  [The  minute  arteries  ramify  in  tufts  orpenicilli.] 

t  Delasonne  has  described  the  structure  of  the  spleen  in  the  ox  as  belonging  to  the  human  subject. 

t  [According  to  Mr.  Kiernan,  these  venous  cells  are  lateral  dilatations,  which  communicate  with  the  venous 
trunk  by  small  branches.  They  contain  only  blood,  however,  for  the  red  pulpy  matter  of  the  spleen  is  said  by 
Miiller  to  be  external  to,  and  not  within  them.  This  red  substance  consists  principally  of  red  granules,  about 
the  size  of  the  blood-globules,  but  spherical,  not  flattened.]  ■ 

t)  It  has  been  erroneously  asserted  that  the  communication  between  the  artery  and  vein  is  more  direct 
in  the  .spleen  than  in  any  other  organ.  The  great  anastamoses,  visible  to  the  naked  eye,  between  the  splenic 
artery  and  vein,  admitted  by  Spigelius,  Diemerbroeck,  Bartholin,  and  others,  are  purely  imaginary.  The  pre- 
cise mode  of  communication  is  still  unknown. 


THE   SPLEEN.  407 

water  will  return  by  the  veins,  at  first  turbid,  then  merely  tinged,  and  at  last  limpid  and 
pure.*  I  have  in  vain  attempted  to  force  the  injection  from  the  veins  into  the  arteries. 
After  the  water,  air  should  be  blown  into  the  artery,  so  as  to  empty  the  spleen  as  much 
as  possible  of  any  liquid  which  it  may  contain. 

If  we  examine  a  spleen  thus  freed  of  its  contained  matter,  we  observe  that  it  is  wrin- 
kled, and,  as  it  were,  shrivelled  on  the  surface,  and  remarkably  diminished  in  bulk ;  and, 
on  making  a  section  of  it,  we  find  a  white,  spongy  tissue,  composed  of  laminae  or  fibres, 
interlacing  in  every  direction. 

The  following  preparationt  exhibits  this  structure  most  fully  :  The  spleen  of  a  horse, 
prepared  in  the  way  I  have  indicated  above,  and  weighing  one  pound,  could  receive  ten 
pounds  of  tallow.  Tlie  injection  was  thrown  in  by  the  veins  :  at  each  stroke  of  the  pis- 
ton, the  spleen  swelled  up  readily,  an  evident  proof  that  the  splenic  cells  communicate 
directly  with  the  veins ;  while,  in  order  to  obtain  the  same  effect  by  injecting  through 
the  arteries,  very  considerable  force  was  required.  The  injection  of  the  spleen  by  the 
veins  did  not  take  place  in  a  uniform  manner,  but  successively ;  in  one  injection,  the 
upper  part  was  injected  before  the  lower,  and  the  anterior  border  before  the  posterior. 
The  independence  of  different  portions  of  the  spleen  on  each  other  exists  in  regard  to 
their  veins  as  well  as  their  arteries.  I  have  been  enabled  to  observe  the  resistance  of- 
fered by  the  tissue  of  the  spleen  to  the  distending  power ;  a  resistance  which  caused 
the  injection  to  flow  back  whenever  the  impelhng  force  was  discontinued.  The  cells 
are  extensible  to  a  certain  degree,  beyond  which  they  resist  very  powerfully ;  it  does 
not  appear  that  they  possess  any  elasticity.J 

After  some  days,  when  desiccation  was  complete,  the  spleen  thus  injected  was  divided 
into  several  portions,  which  were  then  immersed  in  spirits  of  turpentine  moderately  heat- 
ed. The  tallow,  by  which  all  the  cells  were  distended,  and  which  had  taken  the  place 
of  their  contents,  having  been  dissolved  out,  the  sections  presented  a  spongy,  areolar 
structure,  like  that  of  erectile  tissue,  as  found  in  the  corpora  cavernosa,  or  the  substance 
of  the  placenta :  and  this  cannot  be  considered,  as  Meckel  would  have  it,  as  the  artificial 
result  of  the  insufflation  and  injection,  which  lacerate,  as  he  believes,  a  part  of  the  ves- 
sels and  fibrous  tissue. — (Manuel  d' Anatomic,  t.  iii.,  p.  479.)  This  spongy  cellular  struc- 
ture explains  why  the  spleen,  as  well  as  the  corpora  cavernosa,  is  susceptible  of  such 
great  variations  in  bulk ;  and  why  it  is  sometimes  found  collapsed  and  wrinkled,  and 
sometimes  distended,  and,  as  it  were,  swollen.  Are  the  splenic  cells  lined  by  the  inter- 
nal membrane  of  the  veins  T  if  so,  the  membrane  is  so  thin  as  to  be  incapable  of  dem- 
onstration. 

Corpuscles  of  the  Spleen. — Malpighi  described,  as  existing  in  the  spleen,  certain  cor- 
puscles, regarded  by  him  as  the  principal  elements  in  this  organ,  and  believed  by  him  to 
effect  some  important  changes  in  the  splenic  bloodt  These  corpuscles,  which  Ruysch 
considered  to  be  essentially  vascular,  have  been  again  brought  into  notice  by  Dela- 
sonne,  who  demonstrated  them  by  maceration.  Haller  denied  their  glandular  nature, 
because,  as  he  said,  there  can  be  no  glands  where  there  is  no  secretion  and  no  ex- 
cretory ducts.  The  question  is  not,  however,  whether  these  corpuscles  are  glands  or 
not,  but  rather  whether  they  exist  at  all.  It  is  certain  that,  in  many  animals,  in  the  dog 
and  the  cat,  for  example,  a  great  number  of  granules  may  be  seen  scattered  through  the 
spleen,  and  which,  according  to  a  calculation,  the  accuracy  of  which  I  do  not  guarantee, 
would  seem  to  form  two  fifths  of  the  weight  of  the  organ.  These  corpuscles  are  soft, 
whitish  or  reddish,  and  vary  in  diameter  from  a  fourth  of  a  line  to  a  line.  They  do  not 
appear  to  me  to  exist  in  man.^ 

The  lymphatic  vessels  of  t^e  spleen  are  divided  into  the  superficial  and  deep.  The  su- 
perficial only  are  well  known ;  a  certain  number  pass  from  the  spleen  to  the  stomach ; 
they  all  terminate  in  lymphatic  glands  situated  opposite  the  hilus,  within  the  layers  of 
the  gastro-splenic  omentum. 

*  This  injection,  which  requires  considerable  force,  continued  without  interruption  for  a  long  time,  occa- 
sions an  exudation  of  a  perfectly  transparent  fluid  upon  the  surface  of  the  spleen,  even  when  water  returned 
by  the  vein  is  stiU  turbid.  Here  we  have  an  imitation  of  an  exhalant  process.  And,  as  this  transudation  takes 
place  without  Tupture,  it  is  evident  that  there  are  a  set  of  vessels  by  which  it  is  effected.*  Instead  of  making 
an  injection,  which  is  always  troublesome,  we  may  attach  the  splenic  artery  to  a  tube,  which  is  itself  adapted 
to  another  tube,  running  from  the  bottom  of  a  cistern  ;  the  column  of  water  will  overcome  the  resistance  offered 
to  its  passage  from  the  arteries  into  the  veins,  and  in  twenty-four  hours  it  will  pass  through  perfectly  limpid. 

t  This  mode  of  preparation  was  suggested  to  me  by  the  plan  adopted  with  the  corpora  cavernosa  by  Bogros, 
prosector  to  the  Faculty,  who  died  a  victim  to  his  zeal  for  science. 

t  [The  lining  membrane  of  these  venous  cells  is  not  veiy  eitensible,  but  the  trabecuUe,  between  which  they 
lie,  are  highly  extensible  and  elastic  also.] 

^  [The  corpuscles  here  described  are  not  those  discovered  by  Malpighi,  but  large,  soft,  grayish  bodies,  rare- 
ly found  in  the  human  spleen,  and  the  nature  of  which  is  not  understood.  The  Malpighian  corpuscles  are 
much  smaller  ;  they  are  very  evident  in  the  ox,  sheep,  and  pig  ;  they  lie  in  the  red  pulpy  matter  externally 
to  the  venous  cells,  and  are  attached  by  short  pedicles,  or  without  pedicles,  to  the  minute  arteries,  which, 
however,  have  not  otherwise  any  special  relation  to  them ;  they  contain  grayish  granules,  similar  in  size  and 
form  to  those  of  the  red  pulpy  matter.     In  the  human  spleen  they  are  very  difficult  to  distinguish. 

The  extremities  of  the  divided  trabeculse  may  be  mistaken  for  white  corpuscles.] 

*■  [This  transudation  evidently  depends  on  the  porosity  or  permeability  of  animal  tissues,  and  not  on  the  ex- 
istence of  any  special  vessels.] 


408  SPLANCHNOLOGY. 

Nerves. — The  nerves  are  derived  from  the  solar  plexus,  and  are  termed  the  splenic 
plexus.  It  has  been  stated  that  some  terminal  divisions  of  the  pneumogastric  have  been 
seen  distributed  upon  the  spleen.  Several  of  the  nerves  are  remarkable  for  their  size, 
which  enables  us  to  examine  in  them  the  peculiar  structure  of  the  ganglionic  nerves, 
and  also  to  trace  the  splenic  nerves  themselves  deeply  into  the  substance  of  the  organ.* 
We  are  completely  ignorant  of  their  mode  of  termination. 

As  to  the  proper  ducts  of  the  spleen,  said  to  pass  directly  from  that  organ  to  the  great 
cul-de-sac  of  the  stomach,  or  even  to  the  duodenum,  and  to  pour  into  these  parts  a  pecu- 
liar liquid,  it  may  be  confidently  stated  that  they  are  purely  imaginary.  And  again,  the 
three  kinds  of  vascular  conununication  between  the  spleen  and  the  stomach  cannot  in 
any  way  explain  the  afflux  of  liquids  from  the  spleen  to  the  stomach ;  in  fact,  the  arte- 
rial vasa  brevia  of  the  stomach  are  given  off  from  the  splenic  artery  before  it  reaches 
the  spleen ;  nor  do  the  venous  vasa  brevia  enter  the  splenic  vein  until  after  it  has  left 
the  hilus  of  the  spleen  ;  the  lymphatic  vessels  alone  pass  directly  from  the  spleen  to  the 
stomach,  but  they  are  superficial,  and  have  no  connexion  with  the  splenic  cells. 

There  is  no  cellular  tissue,  properly  so  called,  in  the  spleen,  which,  nevertheless,  is 
liable  to  inflammation. 

Development. — In  opposition  to  the  liver,  the  spleen  is  smaller  in  proportion  as  it  is  ex- 
amined nearer  the  period  of  conception.  It  appears  late  ;  it  begins  to  be  distinguisha- 
ble towards  the  end  of  the  second  month,  and  it  then  resembles  a  clot  of  blood.  I  hav^e 
never  seen  it  developed  from  separate  lobules,  which  were  afterward  to  be  united  by  a 
common  investment.  At  birth,  its  proportions  are  almost  the  same  as  at  subsequent  pe- 
riods. The  spleen  is  hard,  and,  as  it  were,  tense,  in  most  infants  who  die  during  birth : 
this  is  probably  owing  to  impeded  circulation. 

The  changes  which  the  spleen  undergoes  during  growth,  both  in  density  and  in  size,  are 
partly  physiological,  which  are  not  very  remarkable,  and  partly  pathological ;  these  are  very 
considerable,  but  they  are  foreign  to  my  subject.  In  the  aged,  the  spleen  decreases,  like 
all  other  organs  ;  and  atrophy  of  this  organ,  which  may  proceed  so  far  that  it  only  weighs 
a  few  drachms,  is  often  accompanied  by  the  development  of  a  cartilaginous  shell. 

Functions. — The  functions  of  the  spleen  appear  to  me  to  be  referrible  to  its  structure 
and  its  vascular  connexions.  The  quantity  of  blood  which  passes  through  it,  its  entire- 
ly vascular  structure,  and  the  physical  qualities  of  the  splenic  pulp  prove,  on  the  one 
hand,  that  the  blood  sent  to  the  spleen  serves  other  purposes  besides  that  of  nutrition ; 
and,  on  the  other,  that  it  undergoes  some  important  changes,  of  which  we  are  complete- 
ly ignorant,  because  the  means  of  analysis  are  wanting ;  but,  whatever  they  may  be,  they 
have  undoubtedly  some  connexion  with  the  functions  of  the  liver,  t  for  in  all  animals 
possessing  a  spleen,  even  though  its  arterial  blood  does  not  come  to  it  from  the  same 
trunk  as  the  hepatic  artery,  the  veins  of  the  spleen  terminate  in  the  venous  system  of 
the  liver.  It  is,  therefore,  extremely  probable  that  the  spleen  performs  an  important 
office  in  the  abdominal  venous  system  ;  but  what  this  office  is  we  do  not  know  ;  and 
what  tends  to  confound  all  our  calculations  is,  that  extirpation  of  this  organ  in  animals 
does  not  seem  to  have  any  marked  effect  upon  their  health,  that  the  most  complete  atro- 
phy of  the  spleen  is  consistent  with  the  most  regular  performance  of  all  the  functions, 
and  that  hypertrophy,  even  to  such  a  degree  that  the  organ  occupies  almost  the  whole 
of  the  abdomen,  merely  produces  a  discoloration  of  the  skin,  diminished  nutrition,  and, 
in  young  subjects,  an  arrest  of  growth. 

The  spongy  and  vascular  texture  of  the  spleen,  and  the  absence  of  valves,  which  al- 
lows the  venous  blood  to  regurgitate  into  the  spleen  when  there  is  any  obstacle  to  the 
circulation,  has  led  to  the  opinion  that  the  spleen  is  nothing  more  than  a  diverticulum 
intended  to  restore  the  equilibrium  of  the  abdominal  venous  system  whenever  it  is  de- 
ranged ;  and  this  opinion,  which  we  owe  to  Haller,  is  pretty  generally  admitted.^  A 
modification  of  this  opinion  is,  that  the  spleen  fulfils,  with  regard  to  the  circulation  in 
general,  and  especially  to  the  abdominal  circulation,  the  office  of  the  safety-tube  of  Wolf 
in  chemical  apparatus.  It  is  certain  that  compression  of  the  splenic  vein  in  a  living  an- 
imal causes  tumefaction  of  the  spleen,  which  gives  place  to  a  quick  collapse,  as  if  by 
elastic  contraction,  when  the  pressure  on  the  vein  is  removed :  it  is  certain  that  the 
whole  structure  of  the  spleen  indicates  that  this  organ  may  undergo  alterations  of  ex- 
pansion and  turgescence,  and  of  collapse  and  flaccidity ;  and  it  is  known  that,  during  in- 
termittent fever,  the  spleen  may  be  felt  below  the  false  ribs,  &c.  But  all  this  leads  to 
presumptions,  and  not  to  certainty. 

From  the  preceding  considerations,  it  would  follow  that  the  spleen  is  only  an  accesso- 
ry organ. 

*  The  sensibility  of  the  spleen  is  very  important.  In  a  living  animal  it  may  be  cat  or  torn  without  an> 
apparent  signs  of  pain.  Dogs  have  been  seen  devouring  their  own  spleens,  which  had  been  drawn  out  of  the 
abdomen'.  What  a  diiference,  in  this  respect,  between  the  spleen  and  the  intestine!  and  yet  they  derive 
their  nerves  from  the  same  source. 

t  We  cannot  state,  with  Malpighi,  that  the  spleen  is  the  preparatory  organ  of  the  bile,  because  we  have 
seen  that  it  is  extremely  probable  that  the  liver  is  concerned  in  the  process  of  sanguification. 

t  May  we  not  quote,  in  support  of  tliis  view,  the  pain  felt  in  the  region  of  the  spleen  after  violent  running, 
which  can  only  be  referred  to  extreme  di&teusiou  of  this  organ  ' 


THE   LUNGS.  40& 


THE  ORGANS  OF  RESPIRATION. 

General  Observations. — The  Lungs  and  Pleura. — The  Trachea  and  Bronchi. — Development 
of  the  Lungs. — The  Larynx — its  Structure,  Development,  and  Functions. — The  Thyroid 
Gland. 

After  describing  the  digestive  apparatus,  the  object  of  which  is  to  elaborate  soHd  and 
liquid  materials  for  the  reparation  of  the  waste  that  occurs  in  the  body,  and,  at  the  same 
time,  to  present  a  vast  surface  for  the  absorption  of  those  materials,  we  naturally  turn 
to  the  consideration  of  the  apparatus  of  respiration,  the  object  of  which  is  to  renew  the 
Tital  properties  of  the  blood  by  the  action  of  atmospheric  air  in  the  lungs. 

This  latter  apparatus,  whicli  is  much  less  complex  than  the  former,  is  composed,  1.  Of 
the  lungs,  the  essential  organs  of  respiration  ;  2.  Of  the  thorax,  a  cavity  forming  a  sort 
of  bellows,  and  having  walls  capable  of  alternately  expanding  and  contracting ;  3.  Of  a 
tubular  apparatus,  by  which  the  lungs  communicate  with  the  external  air,  and  which 
consists  of  the  bronchi,  trachea,  larynx,  pharynx,  and  nasal  fossce;  for  it  is  only  accidental- 
ly, so  to  speak,  and  in  order  to  render  respiration  more  certain,  that  air  is  allowed  to 
pass  through  the  mouth. 

The  thorax  has  been  already  described  (see  Osteologt  and  Myology),  and  also  the 
pharynx,  which  is  common  to  both  the  respiratory  and  digestive  passages. 

The  nasal  fossae,  situated  at  the  entrance  of  the  respiratory  passages,  form  the  natu- 
ral passages  for  the  introduction  of  the  air,  and,  at  the  same  time,  serve  for  the  reception 
of  the  organ  of  smell,  by  which  sense  we  may  consider  the  qualities  of  the  air  are  exam- 
ined. Their  bony  framework  has  been  already  described  under  osteology.  The  pitui- 
tary membrane  which  covers  the  irregular  surfaces  of  these  fossae  will  be  described  in 
the  article  devoted  to  the  organs  of  the  senses ;  we  shall  only  consider,  in  this  place, 
the  lungs,  the  trachea,  and  the  larynx. 

The  Lungs. 

The  lungs  (pulmoncs ;  mevfiuv,  from  Trviu,  to  breathe,  p  p,figs.  155,  170,  171)  are  the 
essential  organs  of  respiration.  While  the  presence  of  an  alimentary  canal  is  the  attri- 
bute of  all  animals,  that  of  lungs  is  limited  to  those  vertebrata  which  live  in  the  air,  dif- 
ferent modes  of  respiration  prevailing  in  the  other  classes. 

Number. — The  lungs  are  two  in  number  ;  but,  as  the  air  which  penetrates  them  is  re- 
ceived from  one  tube,  and  the  blood  circulating  through  them  is  derived  from  one  vascu- 
lar trunk,  they  must  be  regarded  as  separated  parts  of  a  single  organ ;  by  this  arrange- 
ment, respiration  is  rendered  certain,  and  its  unity  maintained. 

Situation. — The  lungs  are  situated  {p  p,  fig.  155)  in  the  thoracic  cavity,  which  is,  in  a 
great  measure,  occupied  by  them,  and  effectually  protects  them  from  the  action  of  exter- 
nal agents  ;  they  are  placed  on  each  side  of  the  heart  {h,figs.  155,  170,  171),  with  which, 
physiologically,  they  are  so  directly  connected ;  they  are  separated  from  each  other  by 
the  mediastinum  (m) ;  hence  the  independence  of  the  two  cavities  in  which  they  are 
contained.  Being  separated  by  the  diaphragm  from  the  stomach,  the  liver,  and  all  the 
other  abdominal  organs,  they  are  so  enclosed  in  all  directions  as  not  to  be  liable  to  dis- 
placements, or,  rather,  such  displacements  are  only  partial,  and  due  to  a  loss  of  substance 
in  the  walls  of  the  cavity  in  which  they  are  placed. 

Size. — The  size  of  the  lungs  necessarily  corresponds  exactly  with  the  capacity  of  the 
thorax,  and  therefore,  like  it,  is  subject  to  variations  ;  and  as,  on  the  one  hand,  the  size 
of  the  lung  is  generally  a  measure  of  the  energy  of  respiration,  and,  on  the  other,  the  en 
ergy  of  respiration  is  a  measure  of  the  muscular  strength,  one  cannot  be  astonished  that 
a  capacious  chest,  coinciding  with  broad  shoulders,  should  be  the  characteristic  of  a  san- 
guine temperament  and  athletic  constitution. 

In  the  natural  state  there  is  neither  air  nor  watery  fluid  between  the  parietes  of  the 
thorsix  and  the  surface  of  the  lung.  The  absence  of  air  or  other  fluid  may  be  shown  af 
ter  death  as  well  as  upon  a  Uving  animal,  by  raising  the  inter-costal  muscle  from  the 
costal  pleura,  so  as  to  preserve  the  latter,*  or  by  removing  the  muscular  fibres  of  the  dia- 
phragm. It  is  then  seen  that  the  lung  is  always  in  contact  with  the  parietes  of  the  chest ; 
in  some  subjects  it  even  appears  as  if  ready  to  escape ;  but  scarcely  is  the  thorax  opened 
when  the  lungs  instantaneously  collapse,  in  consequence  of  the  expulsion  of  the  air  from 
their  interior.  It  is  very  common  to  find  a  small  quantity  of  serum  in  the  cavity  of  the 
pleura,  but  it  is  probable  that  this  fluid  did  not  exist  during  life.  There  is  no  space  to 
be  filled  up  here  as  in  the  cranium. 

The  differences  in  the  size  of  the  lungs  depend,  1.  On  the  state  of  inspiration  or  expi- 
ration. Attempts  have  been  made  to  determine  the  difference  from  this  cause  by  esti- 
mating the  volume  of  air  inspired  or  expired ;  it  is  about  thirty  cubic  inches,  and  may  be 
increased  to  forty  in  forced  inspiration  or  expiration.  2.  On  age  ;  thus,  in  the  foetus,  the 
lungs  are  relatively  much  smaller  than  after  birth.   3.  On  some  morbid  condition.     The 

*  In  order  to  demonstrate  the  absence  of  air,  we  may  also  repeat  another  experiment  performed  by  Haller, 
■which  consists  in  opening  the  thorax  of  a  dead  body  under  water. 

F  F  F 


410  SPLANCHNOLOGY. 

lungs  diminish  in  size  when  the  abdominal  viscera  encroach  upon  the  thorax,  either  m 
ascites,  in  pregnancy,  or  in  diseases  of  the  liver,  vv'hich  organ  has  been  found  in  some 
cases  to  become  enlarged  entirely  by  encroaching  on  the  chest,  and  to  extend  as  high 
up  as  the  second  rib.  They  diminish,  also,  when  the  heart  is  enlarged  in  aneurism,  or 
when  a  large  quantity  of  fluid  is  accumulated  in  the  pericardium.  In  effusions  into  the 
thorax,  the  fluid  takes  the  place  of  the  lung  ;  the  latter  gradually  wastes,  and  is  reduced 
to  such  a  thin  lamina,  or  to  so  small  a  mass,  that  it  has  sometimes  been  overlooked  in 
a  superficial  examination  ;  but  if,  in  such  cases,  air  be  blown  into  the  trachea,  the  organ 
appears  of  its  full  size,  and  gradually  fills  the  remainder  of  the  cavity.  This  extreme 
diminution  of  the  lung,  without  any  alteration  of  its  substance,  proves  that  the  size  of  the 
organ  is  essentially  dependant  upon  the  air  within  it.  Attempts  have  been  made  to  cal- 
culate exactly  the  quantity  of  air  contained  in  the  cavity  of  the  lungs,  or,  in  other  words, 
the  capacity  of  these  organs  :  according  to  one  estimate,  which  can  only  be  regarded  as 
an  approximation  to  the  truth,  it  would  seem  to  be  about  1 10  cubic  inches  after  expira- 
tion, and  140  inches  after  an  ordinary  inspiration. 

When  an  effusion  in  the  thorax  has  been  very  slowly  absorbed,  the  lung  of  the  affect- 
ed side  remains  atrophied,  and  the  thoracic  cavity  contracted,  while  the  other  lung  ac- 
quires a  very  considerable  size,  so  that  the  mediastinum  is  pushed  to  one  side,  and  the 
healthy  lung  passes  beyond  the  median  line.*  In  certain  cases  of  acute  pneumonia,  and 
in  rickets  affecting  the  thorax,  we  often  see  one  of  the  lungs  reduced  to  very  small  di- 
mensions, whUe  the  other  is  very  much  enlarged.! 

The  size  of  the  two  lungs  is  not  absolutely  the  same.  In  consequence  of  the  heart 
projecting  into  the  left  cavity  of  the  thorax,  the  transverse  diameter  of  the  left  lung  is 
not  equal  to  that  of  the  right ;  and  on  account  of  the  projection  of  the  liver  into  the  right 
cavity,  the  vertical  diameter  of  the  right  lung  is  less  than  that  of  the  left.  After  edlow- 
ing  for  these  facts,  the  difference  is  in  favour  of  the  right  lung.  In  determining  the  size 
of  the  lungs,  we  must  bear  in  mind,  that  the  lung  eis  well  as  the  thoracic  cavity  gains  in 
one  direction  what  it  loses  in  another :  elongated  lungs,  which  are  regarded  as  particu- 
larly liable  to  phthisis,  have  not  seemed  to  me  to  be  smaller  than  the  lungs  of  a  person 
of  similar  stature,  but  having  a  broad  chest. 

The  weight  of  the  lungs  must  be  examined  with  reference  to  their  specific  gravity  and 
to  their  absolute  weight.  The  specific  gravity  of  the  lungs  is  less  than  that  of  any  other 
organ,  and  even  much  less  than  that  of  water.  Their  lightness  depends  on  the  great 
quantity  of  air  which  penetrates  them  in  every  direction,  so  that  the  lungs  rise  to  the 
surface  of  the  fluid  in  which  they  are  immersed.  The  specific  gravity  of  the  lungs  pre- 
sents some  important  differences  depending  on  age.  Thus,  before  birth,  and  in  an  in- 
fant that  has  died  during  birth,  without  having  respired,  the  lungs  sink  in  water ;  on  the 
contrary,  they  swim  when  the  infant  has  breathed  ;  not  because  any  change  has  taken 
place  in  the  intrinsic  nature  of  the  organ,  but  because  the  air  has  insinuated  itself  into 
the  cells.  The  estimation  of  the  specific  weight  of  the  lungs  constitutes  what  is  called 
in  legal  medicine  the  hydrostatic  test.  In  the  adult,  the  lung  always  floats,  notwithstand- 
ing any  efforts  which  may  be  made  to  expel  the  air  contained  in  the  pulmonary  cells  ;  it 
seems  as  if  the  air  enters  in  some  way  into  the  composition  of  the  lung,  and  even  in 
vacuo  it  cannot  be  completely  extracted.  The  specific  gravity  of  the  lungs  varies  also 
from  disease.  Thus,  lungs  infiltrated  with  serum,  or  indurated  by  inflammation,  being 
completely  or  partially  deprived  of  air,  on  the  presence  of  which  their  lightness  depends, 
assume,  in  a  greater  or  less  degree,  the  appearance  of  compact  organs,  such  as  the  liver 
or  the  spleen. 

The  absolute  weight  of  the  lung  varies  from  similar  causes.  From  age :  thus,  although 
the  specific  gravity  of  the  foetal  lung  is  much  greater  than  that  of  the  adult,  yet  its  abso- 
lute weight  is  considerably  less.  In  infants  that  have  not  breathed,  the  weight  of  the 
body  is  to  that  of  the  lungs  as  60  to  1,  on  an  average,  while  in  those  that  have  breathed 
the  proportion  is  as  30  to  1,  so  that  the  changes  in  the  lungs  resulting  from  respiration 
are  such  as  to  double  their  weight.  We  may  easily  conceive  the  great  importance  of 
this  fact  in  legal  medicine.  This  method  of  estimating  the  weight  of  the  lungs  is  known 
by  the  name  of  the  static  test. 

The  absolute  weight  of  the  lungs  varies  much  in  disease.  Healthy  lungs  are  very 
light ;  diseased  lungs  may  become  eight  or  ten  times  heavier  than  natural,  without  in- 
creasing in  size.  The  lungs  ahnost  always  becoming  engorged  at  their  posterior  bor- 
der during  the  last  moments  of  life,  their  weight  must  not  be  estimated  from  an  ordinary 
corpse.  It  must  undoubtedly  have  been  from  the  examination  of  engorged  lungs  that 
authors  have  stated  their  average  weight  to  be  four  pounds. 

Colour. — The  colour  of  the  lungs  varies  according  to  age  and  disease.  In  the  fcetus 
they  are  reddish-brown ;  after  birth,  rosy-white ;  in  the  adult  and  in  the  aged  they  are 

*  In  a  case  of  chronic  induration  of  the  left  lung,  the  deviation  of  the  mediastinum  was  so  great,  that  the 
nght  lung  was  in  relation  with  the  left  costal  cartilages. 

t  The  lungs  become  less  increased  in  size  from  inflammation  than  most  other  organs  ;  and  this  peculiarity 
is  explained  by  the  vesicular  structure  of  the  lung,  the  increase  in  size  being  effected  at  the  exp«ase  of  the 
cavity  of  the  air-vesicles. 


♦ffiE   LUNGS.  411 

gra>\sh-blue,  and  almost  always  marked  by  black  spots,  forming  points,  lines,  or  patches, 
and  describing  polygons  more  or  less  regular  in  figure.  These  black  patches,  which  be- 
come much  more  numerous  in  advanced  age,  coexist  with  the  black  deposites  in  the 
bronchial  glands,  and  probably  depend  upon  the  same  cause  ;  they  lie  below  the  serous 
covering  of  the  lungs,  and  are  very  superficial,  excepting  in  disease.  The  posterior  part 
of  the  lung  is  usually  of  a  reddish-brown  colour,  because  it  is  distended  with  blood  and 
serum.  It  has  not  been  shown  that  this  is  altogether  a  post  mortem  condition,  and  the 
necessary  consequence  of  the  position  of  the  corpse  upon  its  back  ;  many  facts  woidd, 
on  the  contrary,  induce  us  to  admit  that  it  occurs  antecedently  to  death. 

Density,  Crepitation,  and  Cohesion. — The  lung,  a  spongy  or  aerial  organ,  so  to  speak, 
is  the  least  dense  of  all  the  organs  in  the  body  ;  it  yields  to  the  pressure  of  the  hand, 
and,  if  no  cause  prevents  the  escape  of  the  air,  it  loses  very  much  of  its  original  size. 
I  have  remarked,  when  speaking  of  the  spleen,  that,  under  pressure,  that  organ  emitted 
a  peculiar  noise,  or,  rather,  gave  rise  to  a  sensation  which  might  be  compared  to  the 
crackling  of  tin,  and  that  this  sound  was  the  result  of  rupture  of  the  fibrous  prolongations 
which  traverse  its  tissue.  Pressure  of  the  lung  causes  a  sensation  and  a  sound  some- 
what analogous  to  the  preceding ;  this  sound  is  called  crepitation.  It  may,  in  fact,  be 
compared  to  the  sound  produced  by  the  decrepitation  of  salt  or  the  rattling  of  paper. 
This  crepitation  is  only  observed  under  a  moderate  pressure,  and  if  the  sensation  com- 
municated be  strictly  noted,  we  shall  find  that  it  is  the  feeling  of  a  resistance  overcome. 
On  careful  examination  of  the  portion  of  the  lung  which  has  thus  crepitated,  bubbles  of 
air  are  found  under  the  pleura ;  in  fact,  emphysema  is  produced.  Notwithstanding  its 
slight  density,  the  tissue  of  the  lungs  possesses  tolerable  strength  ;  it  resists  laceration 
to  a  certain  point ;  and  all  its  parts  are  pretty  firmly  bound  together. 

Resistance  to  Distension. — The  lung,  though  it  yields  to  the  finger  without  recovering 
itself  at  all,  or  only  very  imperfectly,  is  yet  possessed  of  great  elasticity,  but  such  an 
elasticity  as  is  in  harmony  with  its  functions.  It  also  offers  powerful  resistance  to  any 
distending  force.  Thus,  if  a  stopcock  be  adapted  to  the  trachea  of  a  dead  body,  and  the 
lungs  be  inflated  by  means  of  bellows  having  double  valves,  the  pulmonary  tissue  becomes 
extremely  tense  and  hard ;  the  effort  necessary  to  rupture  some  of  the  air-cells,  and  pro- 
duce emphysema,  is  surprising.  In  opposition  to  those  authors  who  speak  of  the  dan- 
gers of  artificial  insufflation  of  the  lungs  of  asphyxiated  persons,  I  have  in  vain  endeav- 
oured, with  aU  the  force  I  could  employ  in  expiration,  to  produce  a  laceration  of  some  of 
the  pulmonary  cells  :  and  how,  it  may  be  asked,  without  great  means  of  opposing  every 
attempt  to  dilate  them  beyond  measure,  could  the  lungs  resist  the  force  to  which  they 
are  subjected  during  violent  exertions  1 

Elasticity. — The  lungs  are  very  elastic,  i.  e.,  they  have  a  constant  tendency  to  tol- 
lapse,  and  to  free  themselves  of  part  of  the  air  contained  in  their  cells.  It  is  this  elasti- 
city which  maintains  the  vaulted  form  of  the  diaphragm  after  the  abdomen  has  been 
opened,  and  occasions  the  lung  to  collapse  suddenly,  when  an  opening  is  made  in 
the  parietes  of  the  thorax :  before  the  chest  is  opened,  the  atmospheric  pressure,  opera- 
ting through  the  trachea,  prevents  the  elasticity  of  the  lungs  from  being  brought  into  ac- 
tion. *  This  elasticity  is  also  shown  by  the  quick  collapse  of  inflated  lungs.  I  have  been 
accustomed  to  demonstrate,  in  my  lectures,  perfectly  healthy  lungs,  preserved  in  alco- 
hol. After  having  shown  how  far  the  inflation  of  the  lungs  may  be  carried,  I  open  the 
stopcock  used  in  the  experiment,  and  the  lungs  instantly  collapse,  driving  out  the  air 
with  considerable  force. 

Shape  and  Relations. — The  lungs  are  shaped  like  an  irregular  cone,  deeply  excavated 
on  the  inner  side,  with  the  base  below  and  the  apex  above  ;  they  present  for  consideration 
an  external  and  an  internal  surface,  an  anterior  and  a  posterior  border,  a  base,  and  an  apex. 

Outer  or  Costal  Surface. — This  surface  is  irregularly  convex,  corresponding  to  the  con- 
cavity of  the  thoracic  parietes,  with  which  it  is  in  contact,  and  on  which  it  is  exactly 
moulded ;  it  is  in  relation  with  the  costal  pleura,  which  separates  it  from  the  ribs  and 
the  intercostal  muscles.  It  presents  a  deep  fissure,  the  inter-lobular  fissure,  which  pen- 
etrates the  entire  thickness  of  the  lung  as  far  as  the  root.  This  fissure  conunences  be- 
low the  apex  of  the  lung  {v',Jig.  171),  passes  downward  and  forward  {v',fig.  170)  as  fair 
as  the  anterior  part  of  the  base,  upon  which  it  encroaches  a  little  at  its  termination.  It 
is  simple  in  the  left  lung  («'),  but  is  bifurcated  in  front  in  the  right ;  the  lower  division 
of  this  bifurcation  continues  in  the  original  direction  ;  the  upper  division  (ic)  passes  up- 
ward and  forward.  The  left  lung,  therefore,  is  divided  into  two  portions  or  lobes,  dis- 
tinguished as  the  superior  («')  and  the  inferior  {u') ;  while  the  right  is  divided  into  three 
lohes,  the  superior  (s),  the  inferior  (m),  and  the  middle  {t).  Of  these  lobes,  the  inferior, 
comprising  the  base  of  the  lung,  is  larger  than  the  superior,  which  forms  the  apex ;  the 
middle  lobe  is  the  smallest.  Tlie  contiguous  surfaces  of  these  lobes  are  plane,  and  cov- 
ered by  the  pleura :  they  are  often  Eidherent,  and  sometimes  purulent  matter  collects  be- 

*  [The  longs  Jo  not  collapse  nntil  the  chest  is  opened,  because  the  atmospheric  pressure  is  exerted  only  on 
the  inner  surface  of  the  lungs,  their  outer  surface  being-  protected  from  it  by  the  unyielding  parietes  of  the 
thorax.  When  this  protection  is  removed,  the  pressure  on  both  surfaces  is  equal,  and  the  elasticity  of  the 
pulmonary  tissue  is  tlien  enabled  to  act.] 


412 


SPLANCHNOLOGY. 


Fig.  170.  tween  them,  and,  being  sm- 

rounded  on  all  sides  by  adhe- 
sions, it  hollows  out,  as  it 
were,  a  cavity  for  itself,  at  the 
expense  of  the  corresponding 
surfaces  of  the  lobes,  and  thus 
simulates  an  abscess  of  the 
lung. 

There  are  many  varieties 
in  the  arrangement  of  these 
lobes.  Thus,  sometimes,  the 
fissures,  and  more  especially 
those  which  bound  the  middle 
lobe,  do  not  reach  as  far  as 
the  root  of  the  lungs,  but  are 
only  slightly  indicated.  Three 
lobes  are  not  unfrequently 
found  in  the  left  lung,  or  four 
in  the  right ;  there  were  four 
lobes  in  the  lung  of  a  negro 
lately  presented  to  the  ana- 
tomical society. 

Examples  are  on  record  of 
lungs  with  five,  six,  and  even 
seven  lobes,  but  in  general  this 
multiplicity  of  lobes  is  only 
rudimentary,  and  represents 
the  normal  condition  in  the 
majority  of  animals.  The  dog, 
the  sheep,  and  the  ox  have 
seven  lobes  in  their  lungs 
Inner  or  Mediastinal  Surface. — This  corresponds  to  the  mediastinum  (p  p).  On  it  we 
observe  the  root  (r)  of  the  lungs,  that  is,  the  part  at  which  they  communicate  with  the 
trachea,  through  the  bronchi,  and  receive  and  emit  their  bloodvessels.  This  root  oc- 
cupies a  very  limited  space  upon  the  inner  surface,  one  inch  in  height,  and  half  an  inch 
in  breadth ;  it  is  situated  at  the  junction  of  the  posterior  with  the  two  anterior  thirds  of 
this  surface,  at  an  almost  equal  distance  from  the  apex  and  the  base. 

That  part  of  the  inner  surface  of  the  Jung  which  is  behind  the  root  corresponds  to  the 
vertebral  column  and  the  posterior  mediastinum,  in  which  are  found,  on  the  left  side,  the 
descending  aorta  and  the  upper  part  of  the  thoracic  duct ;  and  on  the  right  side,  the  vena 
azygos,  the  oesophagus,  and  the  lower  part  of  tlie  thoracic  duct. 

All  that  portion  of  the  inner  surface  which  is  in  front  of  the  root  corresponds  with 
the  anterior  mediastinum,  and  is  excavated  to  receive  the  heart  (l) ;  and  as  the  heart 
projects  more  to  the  left  than  to  the  right  side,  it  follows  that  the  left  lung,  which  cor- 
responds to  the  left  border  and  apex  of  the  heart,  and  higher  up  to  the  arch  of  the  aorta 
ig),  is  more  deeply  excavated  than  the  right  lung,  which  corresponds  to  the  right  auricle 
(m)  and  the  vena  cava  superior  {see  Jig.  170).  We  can  obtain  an  accurate  idea  of  the 
manner  in  which  the  lungs  are  excavated  for  the  reception  of  the  heart  only  by  ex- 
amining them  when  inflated ;  we  are  then  struck  with  the  propriety  of  the  expression  of 
Avicenna,  who  called  the  lung  the  bed  of  the  heart.  We  can  also  understand  how  diseases 
accompanied  with  enlargement  of  the  heart  may  directly  influence  the  respiration,  by 
reducing  the  size  of  the  lungs.  These  organs,  it  may  be  remarked,  are  here  in  apposi- 
tion with  the  heart  through  the  medium  of  the  pericardium  and  the  pleura.  I  should  not 
omit  to  mention  their  relation  with  the  phrenic  nerve,  which  is  affixed  closely  to  the 
pericardium  by  the  pleura.  In  the  foetus,  the  lungs  are  in  relation  anteriorly  with  the 
thjTnus  gland,  which  presses  them  backward. 

The  anterior  border  is  thin  and  sinuous,  presenting  on  the  left  side  two  notches,  one 
inferior  and  very  large,  corresponding  to  the  apex  of  the  heart ;  the  other  superior  and 
small,  for  the  subclavian  artery.  On  the  right  side  there  are  also  two  notches,  but 
smaller  than  those  on  the  left ;  an  inferior  for  the  right  auricle,  and  a  superior  for  the 
vena  cava  superior. 

The  posterior  border  (fig.  171)  is  the  thickest  part  of  the  lung.  It  fills  the  deep  costo- 
vertebral groove  situated  at  each  side  of  the  dorsal  portion  of  the  spine. 

The  base  is  concave,  and  exactly  moulded  upon  the  convexity  of  the  diaphragm  (x, 
fig.  170);  it  is,  therefore,  a  little  more  excavated  on  the  right  than  on  the  left  side. 
Its  circumference  is  very  thin,  and  slightly  sinuous.  Like  the  diaphragm,  the  base  of 
the  lung  forms  an  inclined  plane  from  before  backward  and  downward  ;  and  it  occupies 
the  deep  angular  groove  formed  behind,  between  the  diaphragm  and  the  parietes  of  the 
thorax.     On  account  of  this  obliquity  of  its  base,  the  vertical  diameter  of  the  lung  is  much 


THE    LUNGS.  413 

greater  behind  than  in  front ;  and  as  the  posteiior  border  is  the  largest  part  of  the  organ, 
it  may  be  conceived  that  an  examination  of  the  lung  should  be  directed  chiefly  to  this 
part.  It  is  of  importance  to  form  a  correct  idea  of  the  manner  in  which  the  base  of  the 
right  lung  and  the  convexity  of  the  hver  are  arranged  with  regard  to  each  other.  The 
liver  is,  as  it  were,  received  into  the  concavity  of  the  base  of  the  lung  so  completely,  that 
the  posterior  part  of  this  base  is  almost  on  a  level  with  the  lower  surface  of  the  liver. 
The  relation  of  the  hver  with  the  base  of  the  lung,  which  is  only  separated  from  it  by  the 
diaphragm,  explains  how  abscesses  and  cysts  of  the  liver  may  Jjurst  into  the  lung. 

The  apex  is  obtuse,  and  projects  above  the  first  rib,  a  very  strongly-marked  impression 
of  which  is  found  on  its  anterior  surface.  I  have  observed  that  the  height  of  the  portion 
which  passes  above  the  first  rib  varies  in  different  subjects.  In  severed  I  found  it  from 
an  inch  to  an  inch  and  a  half  In  an  aged  female,  in  whom  the  base  of  the  thorax  was 
extremely  constricted,  the  apex  of  the  lung  (i.  e.,  the  part  bounded  below  by  the  depres- 
sion corresponding  to  the  first  rib)  was  two  inches  in  height.  May  not  the  mechanical 
pressure  of  the  inner  edge  of  the  first  rib  upon  the  apex  of  the  lung  exercise  some  influ- 
ence in  the  very  frequent  development  of  tubercles  in  that  region  1  In  order  to  form  a 
correct  idea  of  the  apex  of  the  lung,  that  organ  must  be  previously  inflated. 

The  whole  surface  of  the  lung  is  free,  smooth,  and  moistened  with  serum ;  it  is  con- 
nected with  the  rest  of  the  body  only  by  its  root,  which  attaches  it  to  the  bronchi  and  the 
heart,  and  by  a  fold  of  the  pleura.  It  is  very  rare  to  meet  with  lungs  free  from  adhe- 
sions upon  their  surface,  so  that  the  older  anatomists  regarded  these  adhesions,  whether 
filamentous  or  otherwise,  as  natural  formations. 

Structure  of  the  Lungs. 

On  examining  the  structure  of  the  lungs,  we  find  in  each  an  investing  membrane  oi 
serous  sac,  formed  by  the  pleura,  and  a  proper  tissue.  We  shall  conmxence  with  the 
pleiira. 

The  Pleura. 

Dissection. — In  order  to  obtain  a  view  of  the  costal  pleura,  saw  through  the  six  or 
seven  upper  ribs  behind,  near  their  angles  ;  cut  through  the  cartilages  of  the  same  ribs, 
at  a  distance  of  some  lines  from  their  sternal  articulations ;  remove  the  intermediate 
portions  of  ribs  and  intercostal  muscles  with  great  care,  so  as  to  leave  the  costal  pleura 
imtouched.     The  cavity  of  the  pleura  may  be  inflated. 

In  order  to  see  the  mediastinal  and  pulmonary  portions,  the  costal  pleura  must  be 
opened,  and  its  continuity  traced. 

The  -pleura  {nXevpu,  the  side)  is  a  serous  membrane,  and,  therefore,  a  shut  sac,  which 
is  extended  partly  over  the  parietes  of  the  thorax,  and  partly  over  the  lungs.  There  are 
two  pleurae,  one  for  the  right  and  the  other  for  the  left  lung.  The  following  is  their  gen- 
eral arrangement : 

The  pleura  lines  the  parietes  of  the  thorax,  the  ribs,  and  the  diaphragm,  forming  the 
pleura  costalis  (p  p,fig.  151)  and  pleura  diaphragmatica ;  it  invests  the  entire  surface  of 
the  lung,  constituting  a  sort  of  integument  for  it,  and  forming  the  pleura  pulmonalis ; 
lastly,  it  is  applied  to  the  pleura  of  the  opposite  side,  so  as  to  form  a  septum  between 
the  two  lungs  ;  this  part  is  the  mediastinal  pleura. 

In  order  to  facilitate  the  description  of  the  pleura,  we  shall  suppose  it  to  commence 
at  a  certain  point ;  and  then,  following  its  course  without  interruption,  shaU  trace  it 
back  to  the  point  from  which  we  started.  If  we  thus  commence  at  the  sternum,  we 
shall  find  that  it  lines  the  internal  surface  of  the  thorax,  being  apphed  to  the  ribs  and 
the  intercostal  muscles,  and  covering  the  mammary  vessels  and  lymphatic  glands  in 
front,  the  intercostal  vessels  and  nerves  behind,  and  the  ganglia  of  the  great  sympa- 
thetic opposite  the  heads  of  the  ribs :  below,  it  is  reflected  upon  the  diaphragm,  and 
covers  the  whole  of  its  upper  surface  :  above,  it  is  reflected  beneath  the  first  rib,  and 
terminates  in  a  cul-de-sao,  intended  for  the  reception  of  the  apex  of  the  lung,  and  pro- 
jecting more  or  less  above  that  rib. 

Having  reached  the  sides  of  the  vertebral  column,  the  two  pleurae  are  reflected  for- 
ward as  far  as  the  root  of  the  corresponding  lung,  and  form,  by  their  approximation,  a 
septum,  which  is  called  the  posterior  mediastinum.  This  septum  contains  within  it  the 
aorta,  the  oesophagus,  the  pneumogastric  nerves,  the  thoracic  duct,  the  vena  azygos,  a 
considerable  quantity  of  cellular  tissue,  a  great  number  of  lymphatic  glands,  and  the 
trachea.     We  see,  then,  that  the  two  pleurae  are  by  no  means  in  immediate  contact. 

Arrested,  as  it  were,  by  the  root  of  the  lungs,  the  pleura  is  reflected  outward  behind 
that  pedicle,  passes  over  a  small  portion  of  the  pericardium,  covers  all  that  part  of  the 
inner  surface  of  the  lungs  which  is  behind  its  root,  and  also  its  posterior  border  and  its 
outer  surface,  dips  into  the  inter-lobular  fissure,  so  as  completely  to  invest  the  contigu- 
ous surfaces  of  the  lobes,  is  reflected  over  their  anterior  margin  upon  their  inner  surface, 
reaches  the  root  of  the  lung,  and  covers  its  anterior  surface,  is  then  reflected  forward 
upon  the  side  of  the  oericardium,  in  front  of  which  it  is  applied  to  the  pleura  of  the  op- 


414  SPLANCHNOLOGY. 

posite  side,  and  at  length  arrives  at  the  border  of  the  sternum,  from  which  we  had  sup- 
posed it  to  commence.* 

The  antero-posterior  septum  formed  by  the  two  plurae,  between  the  sternum  and  the 
root  of  the  lung,  is  called  the  anterior  mediastinum  {m,fig.  155).t  This  septum  is  not 
vertical  nor  median,  Uke  the  posterior  mediastinum,  but  is  directed  downward  and  to 
the  left  side,  an  arrangement  that  is  connected  with  the  oblique  position  of  the  heart, 
which  encroaches  more  upon  the  left  than  the  right  cavity  of  the  thorax.  It  follows, 
from  this,  that  the  uppej  part  of  the  anterior  mediastinum  {p  p,fig.  170)  is  behind  the 
sternum,  while  its  lower  portion  is  behind  the  left  costal  cartilages,  and  hence  the  in- 
terior of  this  mediastinum  may  be  reached  without  opening  the  cavity  of  the  pleura,  by 
Introducing  an  instrument  close  to  the  left  border  of  the  sternum,  opposite  the  fifth  rib. 
The  anterior  mediastinum  is  narrow  in  the  middle,  and  expanded  above  and  below,  Uke 
an  hour-glass.  The  upper  cone  or  expansion  is  very  much  developed  in  the  fcetus,  and 
Is  occupied  by  the  thymus  gland,  which  is  afterward  replaced  by  cellular  tissue :  the 
lower  cone  or  expansion  is  much  larger,  and  contains  the  heart  and  pericardium,  the 
phrenic  nerves,  and  in  front  of  the  heart  a  large  quantity  of  cellular  tissue. 

This  latter,  which  is  so  abundant  in  the  anterior  mediastinum,  communicates  freely 
above  with  the  cellular  tissue  in  front  of  the  neck,  and  below  with  that  of  the  abdominal 
parietes,  through  a  triangular  interval  existing  in  the  diaphragm  behind  the  sternum. 

This  double  communication  explams  how  the  pus  of  an  abscess  formed  in  the  neck 
or  in  the  mediastinum  may  reach  the  surface  in  the  epigastric  region. 

The  pleura  has  two  surfaces,  one  an  external,  the  other  internal. 

External  or  Adherent  Surface. — ^This  does  not  adhere  with  equal  firmness  to  all  the 
parts  which  it  covers.  The  pleura  costalis  is  but  slightly  adherent,  and  may  be  separa- 
ted from  the  ribs  and  the  intercostal  muscles  with  the  greatest  ease.  It  is  sometimes 
raised  in  the  situation  of  these  muscles  by  subjacent  adipose  tissue.  It  is  strengthened 
by  a  layer  of  fibrous  tissue,  which,  notwithstanding  its  tenuity,  performs  an  important 
part  in  diseases  of  the  chest ;  it  explains  why  abscesses  formed  in  the  parietes  of  the 
thorax  so  seldom  open  into  the  cavity  of  the  pleura,  and  why  effusions  into  the  pleura 
are  so  rarely  discharged  externally.  The  diaphragmatic  pleura  is  more  adherent  than 
the  costal.  We  sometimes  find  here,  especially  round  the  pericardium,  some  large  fat- 
ty appendages,  resembling  the  appendices  epiploicae  of  the  great  intestine.  The  pleura 
is  extremely  thin  upon  the  lungs  {pleura  pulmonalis),  where  it  is  not  strengthened  by 
any  fibrous  tissue  ;  and  although  it  is  more  adherent  here  than  the  parietal  pleura,  still 
it  can  be  easily  demonstrated.  The  mediastinal  pleura  is  united  to  the  parts  contained 
within  the  mediastinum  by  very  loose  cellular  tissue,  but  it  adheres  more  firmly  to  the 
Bides  of  the  pericardium,  to  which  the  phrenic  nerves  are  closely  applied. 

The  internal  or  free  surface  is  smooth,t  moistened  with  serum,  and  in  contact  with 
itself  throughout  its  entire  extent,  as  is  the  case  in  all  serous  membranes.  The  adhe- 
sions so  commonly  met  with  here  are  altogether  accidental.  The  structure  of  the  pleura 
is  cellular.^  It  is  doubtful  whether  it  receives  any  arteries  and  veins.  The  vascular 
network,  which  is  sometimes  so  highly  developed  after  pleurisy,  does  not  belong  to  it, 
but  is  situated  upon  its  external  surface.  No  nerves  have  been  traced  into  this  mem- 
brane. 

Uses. — Each  pleura  forms  an  investment  for  the  corresponding  lung,  separates  it  from 
the  parietes  of  the  thorax  and  from  the  other  viscera,  and,  at  the  same  time,  facilitates 
its  movements  upon  the  walls  of  the  thoracic  cavity  by  means  of  the  serosity,  which  is 
constantly  exhaled  and  absorbed  at  its  internal  surface. 

The  Proper  Tissue  of  the  Lungs. 

The  pulmonary  tissue  appears  like  a  spongy  or  vesicular  texture,  the  cells  of  which 
are  filled  with  air.  This  is  rendered  apparent  by  the  most  simple  inspection  of  the  sur- 
face of  an  inflated  lung,  either  with  the  naked  eye  or  with  a  lens.  A  microscopical  ex- 
amination of  sections  of  a  dried  lung  shows  the  existence  of  this  cellular  or  vesicular  tex- 
ture in  the  most  evident  manner  throughout  the  entire  organ.  The  different  shapes  of 
the  cells  and  their  unequal  size  may  also  be  distinguished. 

But  what  are  the  relations  of  the  cells  with  each  other  1  Do  they  communicate 
throughout  the  whole  extent  of  the  lung,  or  only  within  a  determinate  space,  or  are  they 
independent  of  each  other  1  In  order  to  resolve  these  questions,  it  is  necessary  to  ex- 
amine the  lung  of  a  large  animal,  of  the  ox,  for  example,  the  structure  of  which  is  simi- 
lar to  that  of  the  human  lung,  on  which  the  same  observations  may  be  subsequently  re- 

*  [A  fold  of  the  pleura  reaching'  from  the  lower  edge  of  the  root  of  the  lung  downward  to  the  diaphragm, 
is  called  the  ligamentum  latum  pulmonis.  It  is  triangular ;  its  base  is  attached  to  the  diaphragm,  one  side  to 
the  lung,  and  the  other  to  the  mediastinum.] 

t  According  to  Meckel,  the  anterior  mediastinum  is  the  portion  of  the  septum  situated  in  front  of  the  heart, 
just  as  the  posterior  mediastinum  is  the  part  situated  behind  that  organ. 

X  [It  is  covered  with  a  squamous  epithelium,  and  cilia  have  been  observed  upon  it  in  some  of  the  mam- 
malia.] 

^  [Beneath  the  pleura  another  cellular  layer  may  be  demonstrated  ;  and  in  the  lung  of  the  seal  and  leopard 
an  elastic  coat  is  said  to  exist.  1 


THE   LUN38.  415 

peated.  We  then  observe  that  the  surface  of  the  lung  is  traversed  by  lines,  dividing  it 
into  lozenge-shaped  compartments ;  and  if  the  lung  be  previously  inflated,  it  will  be  seen 
that  the  surface  is  slightly  depressed  opposite  these  lines,  but  that  it  bulges  out  between 
them.  If,  by  means  of  a  dehcate  tube,  air  be  blown  under  the  pleura,  or  if  the  lung  be 
forcibly  inflated  through  the  trachea,  so  as  to  rupture  some  of  the  vesicles  and  produce 
emphysema,  we  then  perceive  that  the  lines  bounding  the  lozenge-shaped  intervals  cor- 
respond to  thin  layers  of  very  delicate,  but  tolerably  loose  cellular  tissue,  which  divide  the 
lung  into  a  large  number  of  groups  or  cells,  which  may  be  completely  separated  from 
each  other  by  dissection,  until  at  last  we  arrive  at  the  pedicles  by  which  they  are  united 
into  a  common  mass. 

These  groups  of  cells  are  the  lobules  of  the  lung;  the  cellular  tissue  uniting  them  is  the 
interlobular  cellular  tissue,  which  is  extremely  delicate,  never  loaded  with  fat,  but  oft,en 
infiltrated  with  serosity,  and  is  subject  to  emphysema.  A  great  number  of  lymphatic 
vessels  traverse  this  cellular  tissue :  they  are  often  visible  to  the  naked  eye,  and  are 
always  easily  injected ;  they  pass  deeply  into  the  substance  of  the  lung. 

The  pulmonary  lobules  do  not  communicate  with  each  other,  but  each  is  perfectly  in- 
dependent of  the  rest.  This  fact  is  shown  by  inflation ;  it  is  most  distinctly  proved  by 
dissection ;  and  an  examination  of  the  lungs  of  the  foetus  will  remove  all  doubts  con- 
cerning it.  The  pleura  and  the  interlobular  cellular  tissue  having  but  little  strength  in 
the  fcEtus,  the  lobules  become  separated  without  dissection,  resemble  grapes  attached  to 
their  footstalks,  and  hang  from  a  common  stem,  formed  by  the  divisions  of  the  bronchi 
and  the  pulmonary  vessels. 

This  independence  of  the  lobules  is  also  proved  by  pathological  anatomy :  thus,  we  con- 
tinually find  one  lobule  infiltrated  with  serum,  with  pus,  or  with  tubercular  matter,  in  the 
midst  of  perfectly  healthy  lobules. 

Each  lobule,  then,  is  a  small  lung,  and  may  act  independently  of  those  by  which  it  is 
surrounded.  I  have  satisfied  myself,  by  a  great  number  of  experiments,  that  the  lobules 
are  not  all  equally  permeable  to  the  air,  and  that  a  moderate  inflation  of  the  lungs,  made 
as  much  as  possible  within  the  limits  of  an  ordinary  inspiration,  does  not,  perhaps,  dilate 
one  third  of  the  pulmonary  lobules.  I  have  observed,  and  this  fact  appears  to  me  of 
great  importance,  that  the  most  permeable  lobules  are  those  of  the  apex  of  the  lung ;  and 
this,  perhaps,  will  explain  the  greater  frequency  of  tubercles  in  that  situation.*  There 
are  some  lobules  in  the  lung  which  are  kept,  as  it  were,  in  reserve,  and  only  act  in  forced 
inspirations.! 

The  puhnonary  lobules  vary  much  in  shape  ;  all  the  superficial  ones  resemble  a  pyra- 
mid, the  base  of  which  is  at  the  surface  of  the  lung ;  the  deep  lobules  lie  along  the  bron- 
chial tubes,  have  numerous  facettes,  and  are  exactly  fitted  to  each  other,  like  the  frag- 
ments of  mosaic  work ;  but  they  are  so  irregular  in  form,  that  it  would  be  equally  diffi- 
cult and  useless  to  give  a  description  of  them. 

The  lung,  then,  is  a  collection  of  an  immense  number  of  lobules,  placed  along  the  bron- 
chial tubes  and  pulmonary  vessels,  which  serve  as  a  support  and  framework  for  them,  and 
to  which  they  are  appended  by  pedicles  ;  they  are  united  to  each  other  by  serous  cellu- 
lar tissue,  and  are  all  covered  by  one  great  cell  formed  by  the  pleura,  which  merely 
unites  together  this  great  number  of  parts. 

The  problem  of  the  texture  of  the  lungs  reduces  itself,  therefore,  to  the  determination 
of  the  structure  of  a  single  lobule  ;  but  the  difficulty  is  rather  postponed  than  got  rid  of, 
for  each  lobule  is  a  little  lung,  receiving  an  air-tube  and  an  artery,  and  giving  out  several 
veins  and  lymphatics. 

Before  describing  the  arrangement  of  the  air-tube,  and  the  vessels  in  each  lobule,  we 
shall  say  a  few  words  upon  the  structure  of  the  lobule  itself 

Each  lobule  is  an  agglomeration  of  cells  and  of  vesicles,  all  of  which  communicate 
with  each  other.J  These  cells  are  always  full  of  air.  Their  size  is  not  always  the  same. 
M.  Magendie  has  already  shown  that  the  pulmonary  cells  are  smaller  in  the  infant  than 
in  the  adult,  and  smaller  in  the  adult  than  in  the  aged.§  Nor  is  the  size  of  the  different 
cells  in  the  saime  lobule  constantly  uniform.  All  the  cells  of  the  same  lobule  communi- 
cate, but  they  are  not  all  equally  permeable. t  Thus,  in  a  given  degree  of  inspiration, 
some  cells  only  are  distended,  while  others  require  a  greater  degree  of  dilatation.  The 
septa  between  the  cells  of  a  lobule  are  incomplete,^  and  consist  of  filaments  or  lamellae ; 
and  the  reticulated  arrangement  of  the  cells,  which  is  so  evident  to  the  naked  eye  in  the 
lung  of  the  frog,  seems  to  me  to  represent  with  tolerable  accuracy  the  appearance  of  the 
human  lung  under  the  simple  microscope. 

*  It  is  rather  too  much  to  say  that  pneumonia  almost  always  attacks  the  base  of  the  lungs ;  this  disease  has 
no  special  locality ;  it  perhaps  as  often  affects  the  apex  as  the  base. 

t  In  ordinary  respiration,  perhaps  not  more  than  one  third  of  the  lung  is  in  action  ;  exercise  and  yawning 
are  probably  required,  from  the  necessity  for  bringing  the  whole  lung  into  action.  Thus,  a  great  number  of  tu- 
bercles may  exist  in  the  lung  without  manifesting  their  presence  by  impeding  ordinary  respiration.  It  is  in 
Tiolent  inajnration,  in  exercise,  in  efforts  of  the  voice,  and  in  all  movements  during  which  the  whole  of  the 
lungs  is  called  into  play,  that  we  detect  the  existence  of  a  lesion  in  the  central  organ  of  respiration. 

{  See  note,  p.  419. 

^  Diseases  have  a  remarkable  influence  upon  their  size  ;  in  chronic  catarrh,  and  in  some  varieties  of  asthma, 
we  find  the  pulmonary  cells  excessively  dilated.     Laennechas  called  this  dilatation  pulmonary  emiihysemo. 


416  SPLANCHNOLOGY. 

With  regard  to  the  structure  of  the  cells,*  we  cannot  admit  the  existence  of  muscular 
fibres  round  them ;  the  anatomist  is  unable  to  demonstrate  them,  and  physiology  rejects 
them.  Tlie  most  probable  opinion  is,  that  they  are  formed  of  dense  cellular  tissue,  or  of 
an  elastic  fibrous  tissue,  and  that  the  bloodvessels  are  ranrified  upon  their  parietes. 

The  Air-tubes. 

The  air-tubes  of  the  lungs  consist  of  the  trachea,  the  bronchi,  and  their  divisioris. 

The  Trachea. 

The  trachea  (from  rpaxvg,  rough),  or  aspcria  arteria  ib,fiffs.  170,  171),  is  the  common 
trunk  of  the  air-tubes  of  the  lungs  ;  it  is  situated  between  the  larynx  {a,Jig.  171),  of  which 
it  is  a  continuation,  and  the  bronchi  (p  p'),  which  are  nothing  more  than  its  bifurcation  in 
front  of  the  vertebral  column,  extending  from  the  fifth  cervical  to  the  third  dorsal  verte- 
bra, t  In  this  situation,  however,  it  is  movable,  and  may  easily  be  pushed  to  the  right 
or  left  side.  This  mobility  has  occasioned  serious  accidents  in  tracheotomy,  and  has  led 
to  the  invention  of  an  instrument  for  fixing  the  trachea.^  Its  direction  is  vertical ;  it 
occupies  the  median  line  above,  but  appears  to  be  slightly  deflected  to  the  right  side  be- 
low. I  have  often  seen  it  somewhat  flexuous,  but  these  slight  deviations  only  existed 
when  the  neck  was  bent  upon  the  thorax  ;  they  disappeared  during  extension. 

Dimensions. — The  length  of  the  trachea  equals  that  of  the  space  between  the  fifth  cer- 
vical and  the  third  dorsal  vertebrae,  and  is,  therefore,  from  four  to  five  inches ;  but  it 
varies  according  as  the  larynx  is  raised  or  depressed,  and  as  the  neck  is  flexed  or  ex- 
tended. The  difference  produced  in  its  length,  by  the  utmost  elongation  and  shortening, 
may  be  about  half  its  entire  length,  i.  e.,  from  two  inches  to  two  inches  and  a  half;  its 
shortening  is  limited  by  the  contact  of  its  cartilaginous  rings. ^ 

The  diameter  of  the  trachea  is  determined  by  that  of  the  cricoid  cartilage  of  the  larynx ; 
it  is  much  wider  in  the  male  than  in  the  female,  and  after  than  before  puberty.  Indi- 
viduals who  have  been  many  years  labouring  under  chronic  catarrh  have  the  air-passages 
remarkably  large,  especially  the  trachea.  The  mean  diameter  of  the  trachea  is  from 
ten  to  twelve  lines  in  the  male,  and  from  nine  to  ten  in  the  female.  The  trachea  is  not 
of  equal  diameter  throughout ;  it  is  almost  always  dilated  at  its  lower  extremity,  Avhere 
it  bifurcates.  In  some  subjects  it  gradually  increases  in  size  from  above  downward, 
and  resembles  a  sort  of  truncated  cone,  with  the  base  below. 

External  Surface,  Form,  and  Relations. — In  front  and  on  the  sides  the  trachea  is  cylin- 
drical {fig.  170),  but  is  flattened  behind  {fig.  171),  so  that  it  resembles  a  cylinder,  the 
posterior  fourth  or  third  of  which  has  been  removed.  The  external  surface  is  rough, 
and,  as  it  were,  interrupted  by  circular  ridges,  which  correspond  to  the  cartilaginous  rings. 
The  relations  of  its  external  surface  must  be  examined  in  the  neck  and  in  the  thorax. 

Relations  of  the  Cervical  Portion  (x,fig.  140). — In  front  the  trachea  is  in  relation  with 
the  thyroid  body,  the  isthmus  of  which  being  sometimes  very  narrow  and  sometimes 
very  largely  developed,  covers  a  greater  or  less  number  of  the  rings  of  the  trachea.  In 
general,  the  first  ring  of  the  trachea  is  above  the  isthmus  of  the  thyroid.  Below  the 
thyroid  body  the  trachea  is  in  relation  with  the  stemo-thyroid  muscles,  the  edges  of 
which  are  separated  only  by  the  linea  alba  of  the  neck ;  also  with  the  cerviced  fascia,  the 
thyroid  plexus  of  veins,  a  considerable  quantity  of  cellular  tissue,  the  thyroid  artery  of 
Neubauer,  when  it  exists,  and  the  brachio-cephalic  artery,  which  always  passes  a  little 
above  the  supra-sternal  notch.  All  these  relations  are  of  the  greatest  importance  in  ref- 
erence to  the  operation  of  tracheotomy.  On  the  sides  the  trachea  is  embraced  by  the 
lateral  portions  of  the  thyroid  body,  and,  therefore,  in  diseases  of  that  organ,  the  corre- 
sponding part  of  the  trachea  is  deformed,  flattened  on  the  sides,  and  elliptical,  or  even 
triangular.  The  compression  of  this  canal  may  be  carried  so  far  as  to  produce  suffoca- 
tion. The  common  carotid  artery  and  the  pneumo-gastric  nerve  are  in  contact  with  it 
on  either  side ;  and  hence  the  possibility  of  wounding  that  artery  in  the  operation  of 
tracheotomy.  A  great  number  of  lymphatic  glands  are  situated  upon  the  sides  of  the 
trachea,  and  may  become  so  large  as  to  prevent  the  passage  of  the  air.  Lastly,  all  the 
relations  of  the  trachea,  excepting  those  with  the  thyroid  body,  take  place  through  the 
medium  of  a  very  loose  cellular  tissue  in  which  this  canal  is  imbedded. 

Behind,  the  trachea  is  flat  and  membranous,  and  is  in  relation  with  the  oesophagus, 
which  projects  a  little  beyond  it  on  the  left  side,  and  separates  it  from  the  vertebral  col- 

*  See  note,  p.  419. 

t  The  terai  trachea  is  derived  from  the  roughness  produced  by  the  projection  of  the  cartilages  of  the  wind- 
pipe. The  application  of  the  term  arteria,  by  the  ancients,  to  the  vessels  which  carry  red  blood,  arose  from 
a  serious  anatomical  mistake.  These  vessels  being  habitually  empty  in  the  dead  body,  it  was  supposed  that 
they  contained  air  during  life  ;  and  hence  the  name  artery,  which  tliey  still  retain. 

t  By  a  surgeon  of  the  name  of  Buchot.  The  mobility  of  the  trachea  is  an  obstacle  to  its  puncture  in  the 
operation  of  tracheotomy. 

^  The  elongation  and  shortening  of  the  trachea  is  much  more  limited  in  man  than  in  birds,  in  which  the 
rings  of  the  trachea  are  moved  by  longitudinal  muscles,  and  can  be  drawn  within  each  other  ;  in  the  greatest 
possible  degree  of  shortening  three  rings  overlap  each  other,  so  as  to  equal  only  one  in  height ;  and,  therefore, 
the  trachea  of  a  bird  may  be  diminished  by  two  thirds.  These  peculiarities  of  structure  are  connected  with 
the  different  uses  of  the  parts  ;  the  trachea  in  man  and  other  mammalia  merely  conveying  the  air  (unporte-verU), 
while  tlie  trachea  of  birds  conveys  the  voice  (vn  porte-voix). 


THE   LUNGS. 


417 


omn.  The  left  recurrent  nenre  is  situated  in  the  groove  formed  between  the  trachea  and 
the  oesophagus  in  this  direction  ;  the  right  recurrent  nerve  lies  behind  the  trachea. 

The  inunediate  relation  of  the  trachea  with  the  oesophagus  explains  why  foreign  bodies 
arrested  in  the  gullet  may  produce  suffocation,  and  require  the  perfonnance  of  trache- 
otomy. 

The  softness  and  flexibility  of  the  trachea  opposite  the  oesophagus  have  appeared  to 
some  physiologists  to  be  intended  merely  to  facilitate  the  dilatation  of  the  latter  during 
the  passing  of  the  food ;  but  we  shall  see  that  the  air-tubes  continue  to  be  membranous 
behind,  even  where  they  have  no  relation  with  the  oesophagus,  and  comparative  anatomy, 
which  shows  the  trachea  to  be  cylindrical  in  the  bird,  and  angular  behind  in  the  ox,  the 
sheep,  &c.,  most  completely  refutes  this  opinion. 

Rdaiions  of  the  Thoracic  Portion  of  the  Trachea. — In  the  thorax,  the  trachea  occupies 
the  posterior  mediastinum.  It  corresponds  in.  front,  proceeding  from  above  downward, 
with  the  sternum  and  the  sterno-thyroid  muscles  ;  with  the  left  brachio-cephalic  vein  (c, 
fig.  170) ;  with  the  brachio-cephalic  artery  (A),  an  aneurism  of  which  may  open  into  the 
trachea ;  its  left  side  is,  as  it  were,  embraced  between  the  brachio-cephalic  artery  (A) 
and  the  left  common  carotid  (;) ;  with  the  back  part  of  the  arch  of  the  aorta  {g),  which 
rests  immediately  upon  it,  and  hence  the  dyspnoea  which  so  generfdly  accompanies  aneu- 
rism of  the  aorta,  and  the  frequency  of  its  bursting  into  the  windpipe ;  and,  lastly,  lower 
down,  with  the  bifurcation  of  the  pulmonary  artery,  which  corresponds  with  that  of  the 
trachea. 

The  trachea  is  in  relation  behind  with  the  oesophagus,  which  separates  it  from  the  spinal 
column  ;  and  on  the  sides  with  those  portions  of  the  pleurae  which  form  the  mediastinum, 
with  the  pneumogastric  nerves,  and  with  the  upper  part  of  the  recurrent  nerves. 

In  all  its  thoracic  portion  the  trachea  is  surrounded  by  numerous  lymphatic  vessels  and 
glands,  and  by  a  loose  and  very  abundant  cullular  tissue,  which  communicates  with  that 
of  the  cervical  region.  These  lymphatic  vessels  and  glands  with  the  loose  cellular  tissue 
are  the  parts  immediately  adjoining  the  trachea ;  and  it  may  readily  be  conceived  that 
enlargement  of  the  glands  may  be  productive  of  serious  consequences. 

Internal  Sarface. — The  internal  surface  of  the  trachea  is  of  a  rosy  colour,  and  presents 
the  same  circular  ridges  as  the  external  surface,  but  they  are  more  distinct.  It  is  also 
remarkable  in  its  membranous  portion  for  the  projection  of  certain  vertical  fasciculi,  to 
which  we  shall  again  refer  when  speaking  of  the  structure  of  these  parts. 

The  Bronchi. 

The  bronchi  {(JpSyxoc,  gutter,  p  p,Jig.  171)  are  the  two  branches  formed  by  the  bifiirca- 
tion  of  the  trachea,  which  Ft^.  171. 

spread  out  from  each  other  at 
a  right  or  a  slightly  obtuse 
angle  ;  one  {p)  is  intended  for 
the  right,  the  other  for  the 
left  (p')  lung.  A  tolerably 
strong  triangular  ligament 
exists  at  the  angle  of  the  bi- 
furcation, and  seems  intend- 
ed to  prevent  too  great  sep- 
aration of  the  bronchi. 

The  bronchi  differ  from 
each  other  in  many  respects ; 
first,  in  width.  The  right 
bronchus  is  much  wider  than 
the  left,  and  its  diameter  is 
not  much  less  than  that  of 
the  trachea.  In  a  female 
whose  trachea  w£is  ten  lines 
in  diameter,  the  right  bron- 
chus was  eight,  and  the  left 
five.  This  difference  in  width 
corresponds  with  the  differ- 
ence in  the  size  of  the  two 
lungs,  and  may  afford  a  toler- 
ably correct  measure  of  that 
size ;  they  differ  also  in  length, 
the  right  bronchus  being  one  inch  in  length,  the  left  two ;  also  in  direction,  the  right 
bronchus  passing  less  obhquely  than  the  left,  probably  because  it  enters  the  correspond- 
ing lung  sooner  than  the  latter ;  and,  lastly,  in  their  relations.  Thus,  the  right  bronchus 
is  embraced  by  the  vena  azygos,  which  forms  a  loop  immediately  above  it,  in  order  to 
terminate  in  the  vena  cava  superior.  The  left  bronchus  is  embraced  above  by  the  arch 
of  the  aorta  {g),  and  has  an  important  relation  with  the  oesophagus  behind,  which  it 

Ggg 


4ih  SPLANCHNOLOGY. 

crosses  obliquely.  Both  are  connected  with  the  pulmonary  plexus  of  nerves ;  both  are 
surrounded  with  lymphatic  glands,  remarkable  for  their  black  colour,  and  for  being  fre- 
quently diseased,  and  which  in  some  measure  fill  up  the  angle  formed  by  the  bifurcation 
of  the  trachea  ;  and,  lastly,  both  have  the  following  relations  with  the  pulmonary  artery 
and  veins.  Each  pulmonary  artery  {k  k')  is  situated  in  front  of  the  corresponding  bron- 
chus, then  passes  above,  and  finally  behind  it.  The  two  puhnonary  veins  on  each  side  {I  I, 
mm)  are  situated  upon  the  same  vertical  plane  as  the  corresponding  artery ;  they  pass  up- 
ward in  front  ofthe  artery  and  the  bronchus,  which  is,  therefore,  behind  the  bloodvessels.* 

The  shape  of  the  bronchi  exactly  resembles  that  of  the  trachea,  i.  e,  they  represent 
cylinders,  the  posterior  fourth  of  which  has  been  removed,  and  which  are  formed  by  par- 
allel rings.  The  area  of  the  two  bronchi  is  greater  than  that  of  the  trachea,  in  the  same 
way  as  the  area  of  the  bronchial  ramifications  is  greater  than  that  of  the  bronchi  them- 
selves, so  that  the  velocity  of  the  expired  air  increases  as  it  approaches  the  exterior. 

At  the  root  of  the  lungs  the  bronchi  divide  into  two  equal  branches,  but  in  a  some- 
what different  manner.  The  upper  branch  of  the  bifurcation  of  the  right  bronchus  is  the 
smaller,  and  is  intended  for  the  upper  lobe  of  the  lung,  in  order  to  reach  which  it  is  bent 
slightly  upward.  The  lower  branch,  which  is  larger,  follows  the  original  direction,  and 
after  passing  about  an  inch,  divides  into  two  unequal  branches,  a  small  one  for  the  mid- 
dle lobe,  and  a  larger  one  for  the  lower  lobe.  I  have  once  seen  a  small  bronchus  pro- 
ceeding from  the  lower  part  of  the  trachea  directly  to  the  apex  of  the  right  lung ;  the 
vena  azygos  passed  between  it  and  the  regular  bronchus.t 

The  secondary  divisions  are  precisely  the  same  in  the  two  lungs  ;  each  branch  of  a 
bifurcation  becomes  bifurcated  in  its  turn.  All  these  ramifications  pursue  a  diverging 
course,  some  ascending,  others  descending,  and,  after  proceeding  for  a  variable  distance, 
they  again  bifurcate  ;  so  that,  by  separating  a  small  portion  of  the  pulmonary  substance, 
we  can  see  that  several  diverging  series  of  tubes  proceed  in  succession  from  a  bronchial 
trunk,  and  pass  outward  into  the  tissue  of  the  lung.  The  prevailing  mode  of  division  of 
the  air-tubes  in  the  lungs  is  that  called  dichotomous,  viz.,  a  division  into  two  equal  branch- 
es, which  we  shall  afterward  find  to  be  the  most  favourable  to  the  rapid  transmission  of 
the  contents  of  any  vessel.  (See  Aeteries.)  The  two  branches  of  a  bifurcation  sep- 
arate at  an  acute  angle,  and  a  spur-shaped  process,  situated  within  the  tube  at  the  an- 
gle of  division,  cuts  and  divides  the  column  of  air.  However,  some  small  bronchial 
tubes  are  not  unfrequently  found  arising  directly  from  a  principal  division,  to  be  distrib- 
uted to  the  nearest  pulmonary  lobules.  The  number  of  subdivisions,  which  always  cor- 
responds with  that  of  the  pulmonary  veins,  is  not  so  great  as  might  at  first  be  supposed  ; 
there  are  not  many  more  than  fifteen. 

The  form  of  the  bronchial  ramifications  (bronchia)  differs  essentially  from  that  of  the 
bronchi  themselves  and  of  the  trachea.  They  represent,  indeed,  a  complete  cylinder, 
which  is  not  truncated  behind ;  and  the  cartilages,  instead  of  forming  rings,  have  another 
arrangement,  which  I  shall  point  out  when  speaking  of  their  structure. 

Relations. — The  first  divisions  ofthe  bronchi  are  surrounded,  even  in  the  substance  of 
the  lung,  by  very  numerous  and  dark-coloured  bronchial  lymphatic  glands,  enlargement 
of  which  is  a  very  frequent  result  of  chronic  bronchitis,  and  may  cause  suffocation. 

The  bronchial  ramifications,  as  I  have  said,  support  the  pulmonary  lobules,  which  are 
applied  to  and  moulded  upon  them,  and  are  united  to  them  by  very  loose  cellular  tissue. 

The  following  are  their  relations  with  the  branches  of  the  pulmonary  artery  and  veins : 
the  artery  always  accompanies  the  bronchial  ramification,  and  is  situated  behind  it ;  the 
vein  is  often  separated  from  it ;  the  artery  and  vein  are  not  unfrequently  found  interla- 
ced around  the  corresponding  bronchial  tube. 

Relations  of  the  Bronchial  Ramifications  with  the  Pulmonary  Lobules. — ^Each  pulmonary 
lobule  has  its  bronchial  tube.  This  tube  is  cylindrical,  of  uniform  diameter  throughout, 
and  entirely  membranous  ;  having  entered  the  lobule,  it  dilates  into  a  small  ampulla,  and 
disappears.  There  can  be  little  doubt  that  these  small  ampullae  have  deceived  Malpighi, 
Reisseisen,  and  others,  who  have  stated  that  the  bronchial  tubes  terminate  in  culs-de- 
sac ;  so  that,  according  to  these  authors,  each  pulmonary  cell  is  the  termination  of  a  par- 
ticular bronchicd  tube.  But  it  is  evident  that  such  cannot  be  the  case,  for,  on  the  one 
hand,  the  bronchial  tubes  are  not  sufficiently  numerous,  and,  on  the  other,  it  can  be  shown 
that  only  a  single  bronchial  tube  enters  into  each  group  of  cells  or  each  lobule.  If  we 
inject  with  tallow  a  lung  which  has  previously  been  deprived  of  air,  either  by  an  effu- 
sion in  the  chest  during  life,  or  by  an  artificial  one  after  death,  it  wiU  be  seen  that  the 
injection  is  divided  into  small  globules  or  rounded  tubercles,  which  correspond  to  so 
many  pulmonary  ceUs,  and  that  these  globules  are  all  connected  with  a  common  pedicle, 
corresponding  to  the  bronchial  tube. 

Reisseisen,  who  has  made  this  injection,  thinks  that  the  granular  appearance  of  the 
injected  matter  represents  the  culs-de-sac,  into  which  it  had  penetrated.^ 

*  [In  consequence  of  the  oblique  direction  of  the  left  bronchus  towards  the  root  of  the  lung,  the  correspond- 
ing pulmonary  artery  is  placed  somewhat  above  it,  and  the  pulmonary  veins  below  it ;  on  the  right  side,  the 
pulmonary  artery  is  in  the  middle,  the  bronchus  above,  and  the  veins  below.] 

t  This  appears  to  be  the  natural  arrangement  iu  the  sheep  and  the  ox. 

t  [According  to  Reisseisen,  each  small  bronchial  tube,  on  entering  its  corresponding  lobule,  divides  and  sub- 


THE    LUNGS.  419 

*  ^  Structure  of  the  Trachea,  Bronchi,  and  Bronchial  Ramijicattons. 

Structure  of  the  Trachea. — The  trachea  is  composed  of  a  series  of  imperfect  cartilagi- 
nous rings,  separated  by  an  equal  number  of  fibrous  rings,  and  hence  it  has  a  knotted  ap- 
pearance ;  these  cartilages  keep  the  canal  permanently  open.  Had  the  trachea  been  en- 
tirely membranous,  it  would  have  collapsed  during  inspiration,  which  tends  to  produce 
a  vacuum  in  the  thorax,  and  this  collapse  would  have  prevented  the  entrance  of  the  air. 
The  number  of  the  cartilaginous  rings  varies  from  fifteen  to  twenty.  They  are  more 
prominent  on  the  internal  than  on  the  external  surface  of  the  trachea.  In  some  subjects 
they  form  two  thirds,  in  others  three  fourths  or  four  fifths  of  a  circle.  Each  ring  has 
two  surfaces,  one  anterior  and  convex,  the  other  posterior  and  concave  ;  an  upper  and 
a  lower  edge,  both  of  which  are  thin,  and  give  attachment  to  the  fibrous  rings ;  and  two 
extremities,  which  terminate  abruptly,  without  being  inflected  or  thickened.  In  general, 
there  is  but  little  regularity  in  the  arrangement  of  these  rings ;  they  are  not  exactly  par- 
allel, nor  are  they  of  equal  depth,  which  varies  from  a  line  to  a  line  and  a  half,  two,  or 
even  two  lines  and  a  half;  and  the  same  ring  is  often  of  unequal  depth  at  different  pakits. 
Two  rings  are  often  united  for  a  certain  extent,  and  sometimes  a  ring  is  found  birarca- 
ted ;  indeed,  it  is  probable  that  differences  in  the  number  of  the  rings  depend  upon  their 
thus  uniting  or  dividing.  They  are  sufliciently  thin  to  £illow  of  being  compressed,  so 
that  the  opposite  surfaces  may  touch  without  breaking.  Their  eljisticity  enables  them 
to  recover  their  original  position  immediately,  and  thus  permit  free  access  to  the  air. 
They  can  only  be  broken  when  ossified,  which  is  frequently  the  case  in  the  aged. 

The  first  ring  and  the  two  lower  rings  present  some  peculiarities.  The  first  is  broad- 
er than  any  of  the  others,  especially  in  the  middle  line,  and  it  is  often  continuous  with 
the  cricoid  cartilage.* 

The  last  ring  of  the  trachea,  which  forms  the. transition  between  it  and  the  bronchi, 
has  the  following  characters :  the  middle  part  is  prolonged  considerably  dowmward,  and 
curved  backward,  forming  a  very  acute  angle,  and  is  developed  into  a  spur-shaped  pro- 
jection within  the  trachea,  which  separates  the  two  bronchi.  The  two  half  rings  result- 
ing from  this  arrangement/  constitute  the  two  first  rings  of  the  bronchi.  The  last  ring 
but  one  of  the  trachea  presents  an  angular  inflection  in  the  middle,  less  marked,  howev- 
er, than  that  observed  in  the  lowest  ring. 

The  Fibrous  Tissue  of  the  Trachea. — This  is  arranged  in  the  following  manner :  a 
fibrous  cylinder  commences  at  the  lower  edge  of  the  cricoid  cartilage  ;  the  cartilaginous 
rings  are  situated  within  the  substance  of  this  cylinder  in  such  a  manner,  that  the  thick- 
er layer  of  fibrous  tissue  lies  on  their  exterior,  so  that,  at  first  sight,  their  internal  sur- 
faces would  appear  to  be  in  immediate  contact  with  the  mucous  membrane.  In  the  pos- 
terior part  of  the  trachea,  where  the  cartilaginous  rings  are  wanting,  the  fibrous  tissue 
alone  forms  its  basis  or  framework. 

The  Muscular  Fibres  of  the  Trachea. — If  we  carefully  remove  the  fibrous  tissue  from 
the  back  of  the  trachea,  opposite  its  membranous  portion,  we  arrive  at  certain  transverse 
muscular  fibres,  extending  from  one  end  of  each  ring  to  the  other,  and  also  occupying 
the  intervals  between  the  rings.  The  existence  of  these  muscular  fibres,  which  I  have 
seen  forming  a  layer  half  a  line  tliick  in  certain  cases  of  chronic  catarrh,  cannot  be  doubt- 
ed. It  is  evident  that  their  contraction  must  draw  the  ends  of  the  rings  towards  each 
other,  and  therefore  narrow  the  trachea,  the  diminution  in  the  width  of  which  is  limited 
by  the  contact  of  the  ends  of  the  rings. 

The  Longitudinal  Yellow  Fasciculi. — In  the  membranous  portion  of  the  trachea,  be- 

divides  in  a  certain  uniform  order  into  numerous  tv„  i-rn 

twigs  (<,_/r^.  172),  which,  extending  towards  tbe  °' 

surface  of  the  lobule,  gradually  decrease  in  di- 
ameter, but  increase  in  number,  and  at  length  ter- 
minate in  clusters  of  short,  free,  closed  and  round- 
ed extremities  (c  c) ;  these  are  the  pulmonary 
cells,  which  vary  from  ij^  to  -g^  of  an  inch  in 
diameter.  Not  only  are  the  several  lobules  in- 
dependent of  each  other,  but  the  cells  of  each 
lobule  have  no  communication  with  one  another 
except  indirectly  through  the  twig  or  twigs  from 
which  they  proceed. 

This  view  of  the  minute  structure  of  the  lung, 
which  is  opposed  to  the  opinion  of  M.  Cruveil- 
hier,  receives  support  from  what  is  known  con- 
cerning the  development  of  the  lungs,  and  from 
the  analogy  between  these  organs  and  the  com- 
I)onnd  glands.  ^___^__ 

In_^g'.  172,  after  Reisseisen,  a  shows  the  nat-  "*^^ici^  h 

ural  size  of  the  portion  represented,  magnified 

about  nine  diameters  in  6.     The  bronchial  twigs  Minute  itmcture  of  the  lung, 

and  pulmonary  cells  are  seen  distended  with  air ;  the  knots  or  projections  (i)  on  the  sides  of  some  of  the  ^ga 
indicate  the  commencement  of  other  twigs,  into  which  no  air  has  passed.] 

*  I  have  met  with  one  case  in  which  the  thin  upper  rings  of  the  trachea  and  the  cricoid  cartilage  were 
joined  together,  l)ut  only  on  one  side  ;  the  crico-thyroid  muscle  and  the  inferior  constrictor  of  the  pharynx  ev- 
idently arose  from  the  first  ring  of  the  trachea.  This  continuity  of  the  cricoid  cartilage  with  the  trachea 
manifestly  proves  that  the  rings  of  the  latter  arc  cartilages,  and  not  fihro-cartilag-es. 


420  SPLANCHNOLOGY. 

tween  the  muscular  anS'ttie  mucous  layer,  are  situated  a  great  number  of  parallel,  lon- 
gitudinal, yellow  fasciculi,  which,  at  first  sight,  resemble  longitudinal  folds,  but  are  not 
at  all  effaced  by  distension  ;  these  fasciculi  adhere  to,  and  produce  an  elevation  of,  the 
mucous  membrane,  and  opposite  the  bifurcation  of  the  trachea  they  also  divide,  and  are 
continued  into  the  bronchi. 

The  nature  of  this  tissue  is  not  well  known ;  it  can  only  belong  to  the  muscular  or  to 
the  yellow  elastic  tissue,  though  I  would  rather  incline  to  the  latter  opinion.  According 
to  either  supposition,  its  use  is  to  prevent  too  great  an  elongation  of  the  trachea  and  the 
bronchi ;  actively  in  the  one  case,  and  by  virtue  of  its  elasticity  in  the  other.  Not  un- 
frequently  some  longitudinal  fasciculi  are  found  behind  the  cartilaginous  rings. 

The  Tracheal  Glands. — If  we  carefully  examine  the  posterior  surface  of  the  trachea, 
we  find  a  certain  number  of  ovoid  flattened  glands  (see^^.  171),  placed  upon  the  outer 
surface  of  the  fibrous  membrane  ;  and,  by  removing  this  membrane,  we  see  a  tolerably 
thick,  but  not  continuous,  layer  of  similar  glands  between  the  fibrous  and  the  muscular 
coate  ;  and,  moreover,  if  either  the  inner  or  the  outer  layer  of  the  fibrous  tissue,  situated 
between  the  cartilaginous  rings,  be  removed,  a  series  of  much  smaller  glands  will  be 
found  between  these  layers,  occupying  the  intervals  between  the  rings,  and  even  ex- 
tending behind  them. 

The  Mucous  Membrane. — This  is  a  continuation  of  the  mucous  membrane  of  the  larynx , 
it  is  remarkable  for  its  tenuity,  which  permits  the  colour  of  the  subjacent  parts  to  be 
seen  through  it,  and  for  its  intimate  adhesion  to  the  structures  covered  by  it.  The  lon- 
gitudinal folds  of  which  some  authors  speak  do  not  exist ;  the  yellow  longitudinal  fas- 
ciculi have  been  mistaken  for  them.  Lastly,  it  presents  a  great  number  of  openings, 
from  which  mucus  can  be  expressed.  These  openings  are  nothing  more  than  the  orii- 
ces  of  the  excretory  ducts  of  the  tracheeil  glands.* 

The  Vessels  and  Nerves. — The  arteries  Of  the  trachea  are  derived  from  the  superior  and 
inferior  thyroid.  The  veins  are  generally  arranged  thus  :  some  venous  trunks  running 
along  the  inner  surface  of  the  trachea,  beneath  the  mucous  membrane,  receive  on  each 
side,  in  the  same  manner  as  the  vena  azygos,  small  veins  corresponding  to  the  intervals 
between  the  cartilaginous  rings,  and  then  terminate  in  the  neighbouring  veins.  The 
lymphatic  vessels  are  very  numerous ;  they  enter  the  surrounding  glands,  which  are  of 
considerable  size.  The  nerves  are  derived  from  the  pneumogastrics. 
Structure  of  the  Bronchi. 

The  structure  of  the  bronchi  is  exactly  the  same  as  that  of  the  trachea.  The  lett 
bronchus  has  ten  or  twelve  cartilaginous  rings ;  the  right  has  five  or  six.  They  both 
possess  transverse  muscular  fibres,  longitudinal  yellow  fasciculi,  glands,  &c.  Their  arter- 
ies generally  arise  directly  from  the  aorta,  and  are  named  bronchial.  The  veins  of  the  right 
bronchus  enter  the  vena  azygos  ;  those  of  the  left  terminate  in  the  superior  intercostal. 

Structure  of  the  Bronchial  Ramifications  {Bronchia). — The  fibrous  cylinder  of  the  trachea 
and  the  bronchi  is  prolonged  into  the  bronchial  ramifications.  The  cartilaginous  rings 
are  remarkably  modified  beyond  the  first  division  of  the  bronchi ;  they  become  divided 
into  segments,  which  together  form  a  complete  ring,  so  that  there  is  no  longer  any  mem- 
branous portion,  properly  so  called,  and  the  bronchial  tubes  become  perfectly  cylindrical. 
The  segments  above  mentioned  are  oblong,  curved,  terminated  by  very  elongated  angles, 
and  so  arranged  that  they  can  overlap  and  be  mutually  received  between  each  other. 
They  are  also  united  together  by  fibrous  tissue.  This  arrangement  of  curved  and  angu- 
lar segments  exists  as  far  as  the  last  bifurcations  of  the  bronchial  tubes ;  but  the  size 
of  the  segments  gradually  diminishes,  so  that  they  soon  form  only  narrow  lines,  and  ul- 
timately mere  cartilaginous  points.  The  fibrous  and  membranous  constituents  of  the 
cylinder  preponderate  more  and  more  over  the  cartilaginous  laminae,  which  disappear  be- 
yond the  ultimate  bifurcations  of  the  bronchial  tubes,  being  found  last  at  the  several  an- 
gles of  bifurcation  :  the  ultimate  bronchial  ramifications  are  altogether  membranous. 

The  mucous  membrane  is  prolonged  to  the  very  last  ramifications,  where  it  becomes 
extremely  thin.  The  longitudinal  elastic  fasciculi,  which  were  limited  to  the  membra 
nous  portion  of  the  bronchi,  are  expanded  over  the  entire  surface  of  the  bronchial  tubes 
beyond  their  first  subdivision.  The  muscular  fibres,  which  are  confined  to  the  mem 
branous  portion  in  the  trachea  and  bronchi,  become  circular  on  the  inner  side  of  th» 
bronchial  ramifications,  and  form  an  uninterrupted  but  very  thin  layer,  precisely  resem 
bling  the  circular  fibres  of  the  intestinal  canal,  t    When  we  consider,  on  the  one  hand. 

*  structure  of  the  Trachea.— iTtin  muscular  fibres  of  the  trachea  are  of  the  involuntary  class  (see  p.  323), 
and  are  attached  to  the  internal  surface  of  the  ends  of  the  rings  :  the  longitudinal  fibres  exist  all  round  tht 
trachea,  but  are  collected  into  bundles  on  its  membranous  portion  only  ;  they  are  believed  to  consist  of  elastif 
tissue. 

The  glands  of  the  trachea  and  bronchi  are  compound  ;  its  mucous  membrane  is  covered  vfith  a  columnar 
epithelium,  and  is  provided  with  cilia,  which  urge  the  secretions  upward  towards  the  larynx.] 

t  Structure  of  the  Bronchi  and  their  Branches. — [According  to  Reisseisen,  the  fibrous  cylinder  gradually  de- 
generates, in  the  smallest  bronchial  tubes,  into  cellular  tissue  ;  according  to  the  same  author,  the  longitudinal 
elastic  and  the  circular  fibres  can  be  traced  as  far  as  the  tubes  can  be  opened.  The  contractility  of  the  pul- 
monary tissue  on  the  application  of  galvanism,  recently  observed  by  Dr.  C.  J.  B.  Williams,  establishes  the 
muscularity  of  the  circular  fibres  of  the  bronchial  tubes.  The  mucous  membrane,  as  in  the  trachea,  has  a  co- 
lumnar and  ciliated  epithelium ;  it  of  course  enters  into  and  lines  the  pulmonary  cells.] 


THE    LUNGS.  421 

the  arrangement  of  the  cartilaginous  segments,  which  appear,  as  it  were,  shaped  ex- 
pressly for  the  purpose  of  fitting  between  each  other  at  their  extremities,  and  of  consti- 
tuting an  apparatus  capable  of  being  moved,  and,  on  the  other,  the  existence  of  circular 
contractile  fibres  on  the  inner  surface  of  these  segments,  we  cannot  doubt  that  they  are 
moved  upon  each  other,  the  extent  of  such  motion  being  measured  by  the  space  they 
have  to  traverse  in  order  to  come  into  contact.  When  this  is  effected,  the  canals  must 
be  almost  completely  obliterated.* 

The  Pulmonary  Vessels  and  Nerves. 

Besides  the  trachea,  the  bronchi  and  the  bronchial  ramifications,  which  may  be  re- 
garded as  forming  the  framework  of  the  lungs,  these  organs  receive  two  sets  of  arteries, 
viz.,  the  pulmonary  and  the  bronchial,  and  give  out  two  sets  of  veins,  also  called  _p?<i[wio- 
nary  and  bronchial.  A  very  great  number  of  lymphatics  arise  from  their  interior,  and 
from  their  surfaces,  and  they  are  penetrated  by  important  nerves. 

The  size  of  the  pulmonary  artery  is  equal  to,  if  not  greater  than  that  of  the  aorta ;  J:he 
bronchial  arteries  appear  to  be  distributed  upon  the  bronchi  and  their  ramifications,  which 
they  exactly  follow. 

The  pulmonary  veins  correspond  with  the  pulmonary  artery :  they  are  two  in  number 
for  each  lung.  The  bronchial  veins  correspond  with  the  bronchial  arteries,  and  terminate 
in  the  vena  azygos  on  the  right  side,  and  in  the  superior  intercostal  vein  on  the  left. 

Within  the  lung,  as  well  as  at  its  root,  the  pulmonary  arteries  and  veins  always  ac- 
company the  bronchial  tubes.  The  three  vessels  may  be  distinguished  from  each  other 
upon  sections  of  the  organ  by  the  following  characters :  the  artery  remains  open,  or 
rather  so,  and  is  of  a  white  colour  ;  the  bronchus  is  also  open,  but  of  a  more  or  less  rosy 
colour,  and  contains  a  frothy  mucus,  which  may  be  pressed  out  of  it ;  the  vein  is  collap- 
sed, and  much  more  difficult  to  be  seen  than  the  artery.  The  relations  of  these  three 
kinds  of  vessels  have  not  appeared  to  me  to  be  constant.  Notwithstanding  the  investi- 
gations of  Haller,  the  arrangement  of  the  bronchial  with  regard  to  the  pulmonary  arter- 
ies and  veins  is  not  well  known,  t 

I  ought  to  notice  the  easy  communication  between  the  arteries  and  the  pulmonary 
veins  and  bronchial  ramifications.  The  coarsest  injection  pushed  with  moderate  force 
passes  with  the  greatest  facility  from  the  arteries  into  the  pulmonary  veins  and  the 
bronchial  tubes  ;t  only  infljmied  portions  of  the  lung  have  appeared  to  me  to  be  imper- 
meable. 

The  lymphatic  vessels,  both  superficial  and  deep,  are  very  numerous  ;  they  terminate 
in  the  bronchial  and  tracheal  glands,  the  number  and  size  of  which  sufficiently  declare 
their  importance.  The  black  colour  of  these  glands  only  begins  to  appear  from  the  tenth 
to  the  twentieth  year. 

The  iierves  of  the  lungs  are  principally  derived  from  the  pneumogastrics,  but  they  re- 
ceive some  branches  from  the  ganglionic  system.  They  form  a  large  plexus  behind  the 
bronchi,  with  the  divisions  of  which  they  penetrate  into  the  substance  of  the  lung.  I 
should  observe  that  there  is  only  one  great  pulmonary  plexus  common  to  the  two  lungs ; 
and  on  this  circumstance  the  sympathy  between  the  two  is  without  doubt  partially  de- 
pendant. 

Development. — According  to  Meckel,  the  lungs  are  among  the  latest  organs  to  appear 
in  the  foetus ;  they  can  only  be  distinctly  recognised  amid  the  other  contents  of  the  tho- 
rax, towards  the  end  of  the  second  month  of  intra-uterine  existence.^ 

*  These  anatomical  facts  explain,  in  a  remarkable  manner,  all  the  phenomena  of  nervous  asthma,  nervous 
cuffocation,  &c. 

t  [The  following  are  the  results  of  Reisseisen's  observations  on  this  subject :  the  branches  of  the  pulmonary 
artery  accompany  the  bronchial  tubes,  and  do  not  anastomose  until  their  termination  in  a  dense  network  of 
capillaries  npon  the  walls  of  the  air-cells.  These  capillarie»  have  very  thin  coats  ;  they  are  about  one  twen- 
tieth the  diameter  of  a  pulmonary  cell,  and  the  meshes  which  they  form  are  scarcely  so  wide  as  the  vessels 
themselves.  From  this  network  arise  tlie  branches  of  the  pulmonary  veins,  which  unite  into  larger  and  larger 
trunks,  so  as  to  correspond  with  the  divisions  of  the  pulmonary  artery ;  these  veins  have  no  valves,  and  their 
caliber  is  not  greater,  perhaps  less,  than  that  of  the  artery. 
>  Such  is  the  chief  mcxie  of  distribution  of  the  pulmonary  artery  and  veins  ;  but  both  vessels,  as  indicated  be- 
low, also  communicate  with  the  bronchial  arteries. 

The  bronchial  arteries  are  the  nutrient  vessels  of  the  lung ;  some  of  their  branches  are  distributed  upon  the 
air-tubes  and  to  their  lining  membrane,  even  as  far  as  the  air-cells,  upon  all  the  pulmonary  vessels  and  nerves, 
and  to  the  bronchial  lymphatic  glands  ;  while  others,  passing  between  the  lobules,  or  upon  the  surface  of  the 
lung,  anastomose  with  twigs  from  the  pulmonary  artery,  and  form,  with  the  branches  of  the  pulmonary  vein, 
a  vascular  network  in  those  situations,  but  more  particularly  beneath  the  pleura.  The  branches  distributed 
to  the  lirger  bronchia  and  vessels,  and  to  the  lymphatic  glands,  and  also  some  of  the  vessels  composing  the 
superficial  network,  terminate  in  the  bronchial  veins,  which,  however,  cannot  be  traced  very  deeply  into  the 
substance  of  the  lung.  But  by  far  the  greater  number  of  the  bronchial  arteries  end  in  the  pulmonary  veins  ; 
for  example,  those  distributed  deeply  to  the  smaller  air-tubes  and  pulmonary  vessels,  and  to  the  air-cells,  and 
nearly  all  the  vessels  which  enter  into  the  formation  of  the  interlobular  and  superficial  network.] 

i  [This  is  due  to  rupture  of  the  pulmonary  vessels,  which  have  exceedingly  delicate  coats,  and  are,  perhaps, 
less  supported  by  surrounding  tissue  than  the  vessels  of  other  organs.] 

I>  [The  development  of  the  lungs  has  been  traced  by  various  recent  observers  in  frogs,  birds,  and  mammalia, 
including  man  ;  according  to  Rathke  and  Miiller,  it  closely  resembles,  in  its  early  stages,  that  of  the  compound 
glands.  In  mammaUa,  the  lungs  appear  at  first  as  a  protuberance  upon  the  anterior  part  of  the  (Esophagus, 
consisting  of  a  soft  mass,  like  the  primitive  blastema  of  a  gland  :  within  this  substance  a  more  opaque  portion 
is  formed,  from  which  white  lines  extend,  dividing  and  subdividing,  and  terminating  in  enlarged  extremities 


422  SPLANCHNOLOGY. 

The  lung  is  smallest  at  the  earliest  period  of  its  development.  Its  place  appears  then 
to  be  occupied  by  the  thymus,  which  is  the  only  organ  that  is  seen  when  the  thorax  is 
opened,  the  lungs  being  situated  behind  it,  upon  each  side  of  the  vertebral  column.  The 
development  of  the  lung  takes  place  in  an  inverse  ratio  to  that  of  the  thymus,  the  lung 
increasing  in  proportion  as  the  thymus  diminishes.  In  the  last  two  months  of  pregnancy 
the  lung  is  completely  developed,  and  fit  for  performing  respiration. 

Tlie  weight  of  the  lung  in  the  foetus  and  in  the  adult  presents  some  differences,  which 
are  well  worthy  of  attention.  During  the  whole  period  of  intra-uterine  life,  the  foetal 
lung  is  specifically  heavier  than  water ;  but  as  soon  as  the  infant  respires,  it  become? 
much  lighter,  and  floats  in  water. 

Yet  the  absolute  weight  of  the  lung  is  sensibly  increased,  because  it  receives  a  much 
greater  quantity  of  blood  than  it  did  previously.  Before  birth,  the  absolute  weight  of 
the  lung  to  that  of  the  whole  body  is  as  1  to  60 ;  after  birth,  it  is  as  1  to  30.  It  follows, 
therefore,  that  lungs  which  float  in  water,  and  which  have  acquired  a  much  greater  ab- 
solute weight  than  they  would  have  had  in  the  foetus,  must  belong  to  an  infant  that  has 
respired. 

After  birth,  the  lung  participates  in  the  development  of  the  rest  of  the  body.  At  the 
tmie  of  puberty  it  acquires  the  proportions  which  it  subsequently  presents.  I  have  not 
observed  that  the  lungs  are  smaller  and  lighter  in  the  aged  than  in  the  adult. 

The  colour  of  the  lungs  varies  considerably  at  different  periods.  In  the  earlier  periods 
ot  development,  the  lung  of  the  foetus  is  of  a  delicate  pink  colour  ;  subsequently  it  be- 
comes of  a  deep  red,  like  lees  of  wine,  and  remains  so  until  the  time  of  birth.  After 
birth,  it  again  becomes  of  a  pink  colour.  Still  later,  from  the  tenth  to  the  twentieth 
year,  black  spots  become  visible  at  different  points  along  the  lines  which  form  the  loz- 
enge-shaped intervals  on  its  surface.  These  spots  subsequently  unite  into  lines  or 
patches,  which  give  to  the  grayish  surface  of  the  organ  a  mottled  appearance.  The  de- 
velopment of  the  black  matter  is  so  clearly  the  effect  of  age,  that  it  is  very  rare  not  to 
find  small  masses  of  it  in  the  apex  or  some  other  part  of  the  lungs  in  the  old  subject.  It 
is  worthy  of  notice,  that  the  black  matter  appears  simultaneously  on  the  surface  of  the 
lung,  and  in  the  lymphatic  glands  situated  at  its  root  and  along  the  bronchi. 

With  regard  to  structure,  it  may  be  observed,  that  during  the  four  or  five  earlier  months 
of  gestation,  the  pulmonary  lobules  are  perfectly  distinct  from  each  other ;  they  may  be 
separated  by  very  gentle  traction,  on  account  of  the  weakness  of  the  pleura  and  cellular 
tissue  which  unites  them,  as  compared  with  the  pulmonary  tissue  itself.  The  cartila- 
ginous rings  begin  to  be  visible  after  the  third  month. 

Functions. — The  lungs  are  the  essential  organs  of  respiration,  that  process  by  means 
of  which  the  blood,  though  dark  and  unfit  for  supporting  life  before  entering  these  or- 
gans, becomes  red  and  vivifying.  For  the  accomplishment  of  this  function,  the  lungs 
receive,  on  the  one  hand,  the  atmospheric  air,  and,  on  the  other,  the  venous  blood,  the 
whole  of  which,  in  the  human  subject,  passes  through  the  lungs.  The  air  is  not  drawn 
in  by  any  power  resident  in  the  pulmonary  tissue  itself,  but  by  the  muscular  action  of 
the  parietes  of  the  thorax  ;  the  blood  is  propelled  into  it  by  the  right  ventricle  of  the 
heart.  While  the  blood  undergoes  the  changes  above  mentioned,  the  atmospheric  air 
loses  a  portion  of  its  oxygen,  which  is  replaced  by  carbonic  acid  gas.  The  manner  in 
which  these  changes  in  the  blood  are  effected  is  not  yet  weU  known. 

The  Larynx.* 

It  is  necessary  to  have  several  specimens,  from  subjects  of  different  ages  and  sexes, 
so  as  to  be  able  to  examine  the  genpred  relations  of  the  larynx  in  its  natural  situation ; 
its  cartilages  separated  from  each  other,  its  ligaments  and  muscles,  its  vessels  and 
nerves,  and  its  mucous  membrane. 

The  larynx  is  a  sort  of  box  (jnxis  cava)  or  cartilaginous  passage,  consisting  of  several 
movable  pieces,  which  form  a  complex  apparatus  intended  for  the  organ  of  the  voice. 
It  is  situated  {v,  fig.  140)  in  the  median  line,  in  the  course  of  the  air-passages,  opening 
into  the  pharynx  (3)  above,  and  being  continuous  with  the  trachea  (x)  below  :  it  occu- , 
pies  the  anterior  and  upper  part  of  the  neck,  below  the  os  hyoides,  the  movements  of 
which  it  follows,  and  in  front  of  the  vertebral  column,  being  separated  from  it  by  the 
pharynx :  it  is  covered  by  the  muscles  of  the  sub-hyoid  region,  which  intervene  between 
it  and  the  skin,  and  it  is,  therefore,  veiy  liable  to  woimds,  and  may  easily  be  reached  by 
the  surgeon.  Its  mobility  allows  of  its  being  raised,  depressed,  and  carried  forward  or 
backward,  all  of  which  movements  are  concerned  both  in  deglutition  and  in  the  produc- 
tion of  different  tones  of  the  voice.  It  may  also  be  carried  to  the  right  or  left  side  ;  but 
these  lateral  displacements  are  most  commonly  produced  by  external  violence,  or  by  the 
growth  of  tumours. 

these  are  accompanied  by  bloodvessels,  and  are  at  first  solid,  but  soon  become  hollowed  ont,  into  the  trachea, 
bronchi,  bronchial  tubes,  and  air-cells.] 

*  The  voice  belongs  essentially  to  the  functions  of  relation,  and,  therefore,  Bichat  describes  its  organ  after 
the  apparatus  of  locomotion ;  but  the  anatomical  connexions  between  the  larynx  and  ihe  respiratory  organs 
are  such  that  all  animals  provided  with  lungs  have  a  larynx  also,  while  the  larynx  disappears  where  the  lungs 
oease  to  exist. 


THE   LARYNX.  45J3 

Dimensions. — The  larynx  appears  like  an  expansion  of  the  trachea,  and  has,  therefore, 
been  denominated  its  head,  caput  asperez  arteria.  The  exact  determination  of  its  dimen- 
sions, according  to  age  and  sex,  or  in  different  individuals,  and  their  relations  to  the 
various  qualities  of  the  voice,  would  be  extremely  interesting  in  a  physiological  point  of 
view.  Its  greater  size  in  the  male  than  in  the  female,  and  the  development  it  under- 
goes in  both  sexes,  but  especially  in  the  male,  at  the  period  of  puberty,  are  among  the 
most  remarkable  phenomena  in  the  human  economy. 

Form. — It  is  cyhndrical  below,  like  the  trachea,  but  is  expanded  above,  and  becomes 
prismatic  and  triangular.  It  may,  therefore,  be  compared  to  a  three-sided  pyramid,  the 
truncated  apex  of  which  is  directed  downward  and  the  base  upward ;  it  is  perfectly  sym- 
metrical. 

As  the  larynx  is  a  very  complicated  organ,  I  shall  describe,  in  succession,  the  numer- 
ous parts  which  enter  into  its  composition.  Being  intended  to  admit  of  the  continual 
passage  of  the  air  in  the  act  of  r-espiration,  it  must,  therefore,  present  a  constantly  per- 
vious cavity,  having  strong  and  elastic  wedls  ;  but  as  it  is  also  the  organ  of  the  voice,  it 
requires  to  be  provided  with  a  movable  apparatus,  subject  to  the  wiU.  We  accordingly 
find  in  it  a  cartilaginous  skeleton  or  framework,  much  stronger  than  that  of  the  trachea ; 
certain  articulations  and  ligaments,  and  a  vocal  apparatus,  composed  of  four  fibrous 
bands,  or  vocal  cords ;  muscles,  which  move  the  different  pieces  of  the  cartilaginous 
skeleton,  and  produce  certain  changes  in  the  vocal  apparatus  indispensable  for  the  pro- 
duction of  sounds ;  a  mucous  membrane,  lining  its  inner  surface ;  glands,  which  pour 
out  their  fluid  upon  that  surface  ;  and,  lastly,  certain  vessels  and  nerves. 

We  cannot  enter  upon  a  general  description  of  the  organ  untU  we  have  studied  sep- 
arately its  constituent  parts. 

The  Cartilages  of  the  Larynx. — ^These  are  five  in  number,  of  which  three  are  median, 
single,  and  symmetrical,  viz.,  the  cricoid,  the  thyroid,  and  the  epiglottis ;  and  two  are  lat- 
eral, viz.,  the  arytenoid,  of  which  the  cornicula  laryngis  are  merely  appendages.  The  car- 
tilaginous nodules,  described  by  some  authors  under  the  name  of  the  cune^orm  cartilages, 
and  situated  in  the  membranous  fold  extending  from  the  arytenoid  cartilages  to  the  epi- 
glottis, do  not  exist  in  the  human  subject. 

The  Cricoid  Cartilage. — The  cricoid  or  annular  cartilage  (c  c',  figs.  173  to  177)  forms 
the  base  of  the  larynx  ;  it  is  much  thicker  and  stronger  than  any  j^^    j73 

of  the  others.  Its  form  is  that  of  a  ring,  whence  its  name  («pi«of , 
a  ring);  it  is  narrow  in  front  (c,fig.  173),  where  it  resembles  a 
ring  of  the  trachea ;  it  is  three  or  four  times  broader  or  deeper 
behind  (c'and  c,fig.  175),  where  it  forms  by  itself  alone  the  great- 
er part  of  the  larynx,  being  there  about  an  inch  in  height.  Li 
front,  its  external  surface  is  sub-cutaneous  in  the  median  line  ;  on 
each  side  it  gives  attachment  to  the  crico-thyroid  muscle,  and 
presents  a  smooth  process  (m,  fig.  177)  for  articulating  with  the 
thyroid  cartilage.  Behind,  where  it  is  covered  by  the  mucous 
membrane  of  the  pharynx,  it  presents  in  the  median  line  a  verti- 
cal projection,  which  gives  attachment  to  some  of  the  longitudi- 
nal fibres  of  the  oesophagus,  and  on  each  side  a  depression  for 
the  posterior  crico-arytenoid  muscle. 

Its  internal  surface  is  covered  by  the  laryngeal  mucous  mem- 
brane. 

Its  lower  border  is  perfectly  circular  and  slightly  waved,  and  is 
connected  by  a  membrane  with  the  first  ring  of  the  trachea ; 
sometimes  it  is  even  united  with  it,  and  can  only  be  distinguished  by  its  greater  thickness. 

Its  upper  border  is  not  exactly  circular,  but  is  oblong  from  before  backward,  as  if  the 
ring  had  been  flattened  laterally.  It  is  cut  very  obUquely  forward  and  downward,  or, 
rather,  it  is  deeply  notched  in  front,  where  it  is  concave,  and  gives  attachment  to  the 
crico-thyroid  membrane  in  the  median  line,  and  laterally  by  its  inner  lip  to  &  fibrous 
membrane,  which  is  continuous  veith  the  inferior  vocal  cord,  and  in  the  rest  of  its  thick- 
ness with  the  lateral  crico-arytenoid  muscle. 

Behind,  and  on  each  side,  is  an  oblong,  articular  facette,  the  arytenoid  facettes  (h  h,fig. 
173),  which  are  directed  outward  and  upward,  and  articulate  with  the  arytenoid  carti- 
lages. Between  these  two  facettes,  the  upper  border  of  the  cricoid  is  horizontal,  and 
very  slightly  notched,  and  gives  attachment  to  the  arytenoid  muscle.  The  upper  bor- 
der of  the  cricoid  cartilage  is,  therefore,  horizontal  behind,  oblique  at  the  sides,  and  hor- 
izontal and  slightly  concave  in  front.  The  arytenoid  facettes  are  situated  upon  the  ob- 
lique portion. 

The  Thyroid  Cartilage. — The  thyroid  or  scutiform  cartilage  (t,figs.  173  to  177),  so  na- 
med because  it  has  been  compared  to  a  shield  (i^upcdf,  a  shield),*  occupies  the  upper 
and  fore  part  of  the  larynx.  It  is  formed  by  two  quadrilateral  plates  (or  alee),  united  at 
an  acute  angle  in  the  median  line,  and  embracing  the  cricoid  cartilage  behind.    Its  aia- 

*  The  name  may  also  have  been  derived  from  its  use. 


424  SPLANCHNOLOGY. 

teriar  or  cutaneous  surface  presents  in  the  median  line  an  angular  projection  (below  c, 
fig.  173),  more  marked  and  deeply  notched  above,  and  completely  effaced  below;  much 
less  distinct  in  the  female,  in  whom  it  forms  only  a  rounded  surface,  than  in  the  male, 
in  whom  it  has  received  the  special  appellation  of  the  pomum  Adami.  This  angular  pro- 
jection does  not  appear  until  puberty ;  it  presents  certain  individual  varieties,  but  these 
do  not  appear  to  me  to  have  any  relation  with  the  qualities  of  the  voice. 

On  each  side  the  surface  {t,  Jigs.  173,  174)  is  smooth  and  quadrilateral,  and  has  two 
tubercles  behind  ;  one  of  which  is  superior  (b),  and  the  other  inferior  {d).  The  latter, 
or  larger,  is  prolonged  upon  the  inferior  border  of  the  cartilage.  The  two  tubercles  are 
united  by  an  aponeurotic  arch,  but  there  is  no  oblique  intermediate  line,  as  has  been  gen- 
erally alfirmed.  These  tubercles,  and  the  imaginary  line  between  them,  separate  the 
anterior  three  fourths  of  the  surface,  which  are  covered  by  the  thyro-hyoid  muscle,  from 
the  posterior  fourth,  which  is  covered  by  the  inferior  constrictor  of  the  pharynx  and  the 
sterno-thyroid  muscle.     The  tubercles  give  attachment  to  these  three  muscles. 

The  posterior  surface  {fig.  175)  presents,  in  the  median  line,  a  retreating  angle,  which 
gives  attachment  to  the  thyro-arytenoid  ligaments,  or  vocal  cords,  and  to  the  thyro-ary- 
tenoid  muscles.  This  angle  is  sometimes  so  acute  that  the  cartilage  has  the  appear- 
ance of  having  been  subjected  to  strong  lateral  pressure. 

On  each  side  {t  t)  the  posterior  surface  projects  beyond  the  cricoid  cartilage,  and  forms 
part  of  the  lateral  groove  of  the  larynx.  It  is  lined  by  the  pharyngeal  mucous  membrane, 
and  corresponds  in  part  to  the  thyro-  and  crico-arytenoid  muscles. 

Its  upper  border  is  horizontal  and  sinuous,  and  gives  attachment  to  the  hyo-thyroid 
membrane  in  its  whole  extent.  It  presents  a  notch  (e,  fig.  173)  in  the  median  line,  which 
is  shallower,  but  broader  and  more  rounded  in  the  female  than  in  the  male.  On  the 
sides  there  is  a  small  prominence,  which  forms  a  continuation  of  the  superior  tubercle,  and 
is  often  wanting.  More  posteriorly,  we  find  on  each  side  a  slight  notch,  bounded  by  cer- 
tain processes  called  the  great  or  superior  comua  {s,  figs.  173,  174)  of  the  thyroid  cartilage. 

The  lower  border  is  sinuous,  and  shorter  than  the  upper,  and  hence  the  pyramidal  shape 
of  the  larynx.  It  presents  a  slight  median  projection,  to  which  the  crico-thyroid  liga- 
ment is  attached  ;  in  the  rest  of  its  extent,  it  gives  insertion  to  the  crico-thyroid  muscle, 
and  presents  a  rough  eminence,  which  forms  a  continuation  of  the  inferior  tubercle  ;  and 
more  posteriorly,  on  each  side,  a  slight  notch,  bounded  by  the  lesser  or  inferior  comua  {I, 
Jigs.  173,  175)  of  the  thyroid  cartilage. 

Its  posterior  borders  (s  r,  fig.  174)  are  slightly  sinuous,  give  attachment  to  the  stylo- 
pharyngei  and  palato-pharyngei,  and  rest  upon  the  vertebral  column.  As  the  thyroid 
cartilage  projects  behind  the  upper  portion  of  the  larynx,  it  may  be  regarded  as  protect- 
ing the  larynx  by  its  posterior  borders  resting  upon  the  vertebral  column. 

The  comua  of  the  thyroid  cartilage  are  four  in  number,  two  superior  and  two  inferior,  and 
appear  to  be  prolongations  of  the  posterior  borders  of  the  cartilage.  They  are  all  round- 
ed, and  are  bent  inward  and  backward  ;  the  upper  or  great  comua  (s)  are  generally  the 
larger,  and  are  united  by  ligaments  to  the  os  hyoides  ;  the  lower  or  lesser  comua  (J)  are 
usually  smaller,  and  articulate  with  the  cricoid  cartilage. 

The  Arytenoid  Cartilages. — The  arytenoid  cartilages  {a,  figs.  173,  175  to  177)  are  two 
in  number,*  are  situated  at  the  upper  and  back  part  of  the  larynx,  and  have  a  pyramidal 
and  triangular  form ;  they  are  directed  vertically,  and  bent  backward  like  the  lip  of  an 
ewer,  whence  their  name  {dptraiua,  a  funnel).  Their  posterior  surface  (fig.  175)  is  trian- 
gular, broad,  and  concave,  and  receives  the  arytenoid  muscle  ;  their  internal  surface  is 
fined  by  the  mucous  membrane  of  the  larynx  ;  their  anterior  surface  (fig.  173)  is  convex, 
narrow,  rough,  and  furrowed,  and  corresponds  to  the  series  of  glands  called  tlie  aryte- 
noid glands,  and  to  the  superior  vocal  cord ;  their  base  is  very  deeply  notched,  articulates 
with  the  cricoid  cartilage,  and  is  terminated  by  two  processes  :  one  posterior  and  exter- 
nal (/),  which  gives  attachment  to  the  lateral  and  posterior  crico-arytenoid  muscles  ;  the 
other  is  anterior  (a),  pyramidal,  and  more  or  less  elongated,  has  the  inferior  vocal  cord 
attached  to  its  point,  and  it  forms  a  fourth,  or  almost  a  third,  of  the  antero-posterior  di- 
ameter of  the  glottis  ;  their  apex  is  surmounted,  or  rather  formed,  by  two  very  small  and 
delicate  cartilaginous  nodules  (g),  which  are  bent  inward  and  backward,  and  iiicurvated 
so  that  they  almost  touch  ;  they  are  called  the  cornicula.  They  were  very  correctly  descri- 
bed by  Santorini,  under  the  name  of  the  sixth  and  seventh  cartilages  of  the  larynx.  They 
are  now  generally  known  as  the  tubercles  of  Santorini,  the  capitula  or  cornicula  laryngis. 
They  appear  to  me  constantly  to  exist,  sometimes  closely  united  with  the  arytenoid  carti- 
lages, and  not  moving  at  all  upon  them,  and  sometimes  perfectly  distinct  and  very  movable. 

The  Epiglottis. — The  epiglottis  (em,  upon,  and  yluTrlg,  the  glottis,  i,figs.  174  to  178), 
or  lingula,  forming  a  movable  and  highly  elastic  valve,  is  a  fibro-cartilaginous  lamina, 
situated  (i,  fig.  140)  behind  the  base  of  the  tongue,  and  in  front  of  the  superior  opening 
of  the  larynx,  not  upon  the  glottis,  as  its  name  would  seem  to  indicate. 

*  It  was  for  a  long  time  believed  that  there  existed  only  one  arytenoid  cartilage,  because  the  larynx  was  al- 
ways examined  when  covered  by  its  membranes  ;  so  that  the  word  arytenoid,  in  the  works  of  Galen,  is  always 
applied  to  the  two  united,  Galen  only  admitted  three  cartilages  in  the  larynx— the  thyroid,  the  cricoid,  and 
the  arytenoid,  . 


^^r 


THE   LARYNX.  42^ 


Its  direction  is  vertical,  excepting  at  the  moment  of  deglutition,  when  it  becomes  hori- 
zontal, so  as  to  protect  the  opening  of  the  larynx  like  a  lid  {laryngis  operculum).  Its  tri- 
angular shape  has  been  well  compared  to  that  of  a  leaf  of  purslaine.  It  must  be  separa- 
ted from  the  neighbouring  parts  to  be  properly  studied. 

It  varies  much  in  size  in  different  subjects,  but  always  appears  to  me  to  bear  some  re- 
lation to  the  dimensions  of  the  upper  orifice  of  the  larynx,  beyond  which  it  almost  al- 
ways projects  when  depressed. 

Its  anterior  or  lingual  surface  presents  a  free  and  an  adherent  portion.  The  free  por- 
tion surmounts  the  base  of  the  tongue ;  it  may  be  felt  by  the  finger,  and  even  seen  by 
strongly  depressing  the  tongue.*  Three  folds  of  mucous  membrane,  one  in  the  middle 
and  one  on  each  side,  pass  from  the  epiglottis  to  the  base  of  the  tongue. 

The  adherent  portion  corresponds  in  front  with  the  base  of  the  tongue,  the  os  hyoides, 
and  the  thyroid  cartilage.  In  order  to  expose  it,  it  is  necessary  to  have  recourse  to  dis- 
section. We  then  find  a  median  glosso-epiglottid  ligament,  which  is  very  strong,  and  com- 
posed of  yellow  elastic  tissue,  and  which,  I  beheve,  assists  in  drawing  back  the  depress- 
ed epiglottis  ;  its  place  is  occupied  by  muscular  fibres  in  the  larger  animals  ;  also  a  hyo- 
epiglottid  ligament,  extending  from  the  epiglottis  to  the  posterior  surface  of  the  os  hy- 
oides ;  and,  lastly,  beneath  this  ligament,  a  yellow  fatty  tissue,  improperly  called  the 
epiglottid  gland,  occupying  the  interval  between  the  epiglottis  and  the  concavity  of  the 
thryoid  cartilage. 

Moreover,  the  anterior  surface  of  the  epiglottis,  examined  in  the  vertical  direction,  is 
concave  above,  convex  in  the  middle,  and  again  concave  below  ;  it  is  convex  in  the  trans- 
verse direction.  The  posterior  or  laryngeal  surface  {figs.  175,  178),  the  curvatures  of 
which  are  the  reverse  of  those  on  the  anterior  surface,  is  free  in  the  whole  of  its  extent, 
and  covered  by  the  laryngeal  mucous  membrane. 

Circumference. — Its  upper  margin,  or  the  base  of  the  triangle  which  it  represents,  is 
free,  bent  forward,  slightly  notched,  and  continuous,  by  two  rounded  angles,  with  its  lat- 
eral margins,  from  each  of  which  proceed  two  folds,  viz.,  the  aryteno-epiglottid  {h,fig. 
178),  extending  from  the  epiglottis  to  the  arytenoid  cartilage,  and  enclosing  a  ligament 
(b,fig.  176),  and  the  pharyngeo-epiglottid,  situated  anterior  to  the  preceding,  passing  al- 
most transversely  outward,  and  lost  upon  the  sides  of  the  pharynx. 

The  epiglottis  terminates  below  in  a  sort  of  pedicle,  which  is  extremely  slender,  and 
is  fixed  {fig.  176)  into  the  retreating  angle  of  the  thyroid  cartilage,  immediately  above 
the  attachment  of  the  vocal  cords.  This  attachment  is  effected  by  means  of  a  ligament, 
called  the  thyro-epiglottid. 

The  epiglottis  is  remarkable  for  the  great  number  of  perforations  found  in  it,  which 
give  it  an  appearance  very  much  resembling  that  of  the  leaves  of  several  of  the  lauracece. 
In  these  foramina  we  find  small  glands,  which,  for  the  most  part,  open  on  the  laryngeal 
surface  of  the  epiglottis.    The  so-called  epiglottid  gland  has  no  relation  with  these  orifices. 

It  is  also  remarkable  for  its  flexibility  and  elasticity ;  on  account  of  which  it  is  classed 
by  Bichat  among  the  fibro-cartilages,  a  sort  of  tissue  which  we  have  stated  does  not  ex- 
ist. Its  yellow  colour  gives  it  an  appearance  like  the  yellow  elastic  tissue.  It  is  brittle, 
and  may  be  crushed  between  the  fingers  ;  this  depends  partly  upon  the  nature  of  its  tis- 
sue, and  partly  upon  the  numerous  foramina  with  which  it  is  perforated,  and  which  ne- 
cessarily diminish  its  strength. 

The  Artictdations  and  Ligaments  of  the  Larynx. 

The  articulations  of  the  larynx  may  be  divided  into  the  extrinsic  and  the  intrinsic. 

The  Extrinsic  Articulations. — The  thyro-hyoid  articulation  consists  of  three  ligaments, 
which  unite  the  thyroid  cartilage  to  the  os  hyoides.     The  middle  jy..  174. 

thyro-hyoid  ligament  {n,  fig.  174)  is  a  loose  yellowish  membrane,  ex- 
tending from  the  upper  border  of  the  thyroid  cartilage  {t)  to  the  os 
hyoides  (m).  Its  vertical  dimensions  are  much  greater  at  the  sides 
than  in  the  middle  ;  and,  therefore,  the  comua  of  the  os  hyoides 
can  be  raised  higher  than  its  body,  and  hence  the  sides  of  the  tongue 
can  be  elevated  so  as  to  form  a  groove,  along  which  the  food  glides. 
This  membrane  is  thick  in  the  middle,  and  thin,  and,  as  it  were, 
cellular  on  each  side. 

Relations. — It  is  sub-cutaneous  in  the  middle,  but  is  covered  on 
each  side  by  the  thyro-hyoid  muscle.  It  corresponds  behind  with 
the  epiglottis,  from  which  it  is  separated  by  some  adipose  tissue, 
and  with  the  mucous  membrane  covering  the  posterior  surface  of 
the  tongue.  It  is  attached  to  the  posterior  lip  of  the  upper  edge 
of  the  OS  hyoides,  not  to  the  lower  edge,  as  is  frequently  asserted. 
It  therefore  passes  behind  the  os  hyoides. 

The  lateral  thyro-hyoid  ligaments  (0)  may  be  considered  as  the  margins  of  the  thyro- 
hyoid membrane.    They  are  small  cords,  extending  from  the  great  comua  of  the  thyroid 

*  I  attach  groat  importance  to  inspection  of  the  epiglottis  in  diseases  of  the  larynx. 
Hb  H 


^88  8PLANCHN0L0GT. 

cartflage  to  the  tubercular  extremities  of  the  great  comua  of  the  os  hyoidea.    We  often 
find  a  cartilaginous  or  bony  nodule  in  these  ligaments. 

There  is  a  very  distinct  synovial  capsule  between  the  posterior  surface  of  the  body  of 
the  OS  hyoides  and  the  upper  part  of  the  thyroid  cartilage.  Its  presence  attests  the  fre- 
quent movements  which  take  place  between  these  parts,  and  during  which  the  middle 
and  upper  part  of  the  cartilage  is  placed  behind  the  os  hyoides. 

The  Tracheo-cricoid  Articulation. — The  first  ring  of  the  trachea  is  connected  with  the 
lower  border  of  the  cricoid  cartilage  by  a  fibrous  membrane  of  the  same  nature  as  that 
between  the  rings  of  the  trachea.  A  small  vertical  fibrous  cord  is  added  to  it  in  the 
median  line  in  front.  This  membrane  permits  some  movements  between  the  cricoid 
cartilage  and  the  first  ring  of  the  trachea,  and  in  these  the  sides  of  the  ring  are  buried 
behind  the  cricoid  cartilage. 

The  intrinsic  articulations  are  the  crico-thyroid  and  the  crico-arytenoid.  I  need  merely 
remind  the  reader  of  the  articulation  between  the  arytenoid  cartilages  and  the  comicula 
larjTigis. 

Tlie  Crico-thyroid  Articulations. — ^These  are  arthrodial.  Each  of  the  lesser  comua  of 
the  thyroid  cartilage  terminate  in  a  plane  surface,  directed  downward  and  inward,  which 
rests  upon  a  similar  plane  surface  {m,fig.  177)  on  the  cricoid  cartilage,  directed  upward 
and  outward.  An  orbicular  or  capsular  ligament  (r,figs.  174, 175),  composed  of  shining, 
fasciculated,  and  parallel  fibres,  surrounds  the  articulation,  which  is  provided  with  a 
synovial  membrane.  The  posterior  fasciculus  is  remarkable  for  its  length  and  shape, 
and  extends  nearly  to  the  crico-arytenoid  articulation.  In  some  subjects  the  orbicular 
ligament  is  very  loose,  in  others  the  articulation  is  exceedingly  close. 

The  movements  are  limited  to  simple  gliding,  combined  with  a  forward  and  backward 
movement  of  the  th3Toid  cartilage.  The  direction  of  the  facettes  upon  the  cricoid  car- 
tilage renders  them  fitted  to  support  the  thyroid. 

The  Crico-thyroid  Membrane,  or  Middle  Crico-thyroid  Ligament. — Besides  the  preceding 
articulations,  the  lower  border  of  the  thyroid  cartilage  is  connected  with  the  upper  border 
of  the  cricoid  by  a  thick  triangular  membrane,  the  pyramidal  or  conoid  ligament  (v,  Jig. 
174),  which  is  attached  in  the  median  line  to  the  lower  border  of  the  thyroid  cartilage, 
and  the  base  of  which  is  fixed  to  the  upper  border  of  the  cricoid  cartilage.  This  mem- 
brane is  fibrous,  thick,  very  strong,  perforated  with  foramina  for  vessels,  and  is  yellow 
and  elastic. 

The  Lateral  Crico-thyroid  Ligament. — This  ligament  {d,fig.  176)  can  be  well  seen 
only  from  the  inner  surface  of  the  larjoix.    It  consists  of  very  strong  fibres,  which  arise 
from  the  inner  lip  of  the  upper  border  of  the  cricoid  cartilage,  in  front  of  the  crico-ary- 
tenoid articulation,  and  pass  horizontally  inward  to  the  retreating  angle  of  the  thyroid 
cartilage,  below  the  insertion  of  the  inferior  vocal  cord  (r).    This  ligament,  which  is  very 
strong,  appears  to  be  continuous  above  with  the  inferior  vocal  cord.    It  is  covered  on 
the  inside  by  the  mucous  membrane  of  the  larynx,  and  it  corresponds  on  the  outside  {d, 
fig.  177)  to  the  thyro-  (e)  and  crico-arytenoid  (/)  muscles,  which  separate  it  from  the 
thyroid  cartilage. 
The  Crico-arytenotd  Articulations. — These  articulations  are  effected  by  mutual  reception. 
The  articular  swr/ace,  upon  the  cricoid  cartilage,  is  an  eUiptical  facette  {h,fig.  173),  di- 
rected obliquely  downward  and  forward,  and  oblong  and  slightly  concave  in  the  same  di- 
rection.    The  base  of  the  arytenoid  cartilage  presents  an  oblong  articular  facette,  deeply 
concave  from  without  inward,  i.  c,  in  an  opposite  direction  to  the  former,  which  it  accu- 
rately receives. 
Means  of  Union. — Properly  speaking,  there  is  only  one  ligsunent,  the  internal  and  poste- 
j^.    ,.-  rior  (e,  fig.  175).     It  arises  from  the  cricoid  cartilage,  and  is  insert- 

^'   '  •  ed  in  a  radiated  manner  into  the  inner  and  back  part  of  the  base  of 

the  arytenoid  cartilage,  and  to  the  inner  side  of  its  anterior  process, 
behind  the  inferior  vocal  cord.  This  ligament  is  very  strong,  but 
yet  suiEciently  loose  to  allow  of  certain  extensive  movements. 
There  is  also  a  very  loose  synovial  capsule,  which  can  be  easily 
demonstrated. 

The  movements  of  this  articulation,  like  those  of  all  similar  joints, 
take  place  in  every  direction ;  but  the  movements  inward  and  out- 
ward are  much  more  extensive  than  those  which  are  performed 
forward  and  backward.     On  account  of  the  mode  of  insertion  of  its 
muscles,  the  arytenoid  cartilage  is  not  moved  in  a  direct  line,  but 
undergoes  a  partial  rotatory  movement,  the  centre  of  which  is  in 
the  articulation.     In  the  movement,  which  is  oblique,  on  account 
of  the  obliquity  of  the  articular  surfaces,  the  apex  of  the  arytenoid 
cartilage  is  carried  either  outward  and  backward  or  inward  and  for- 
ward.   These  motions  should  be  studied  with  the  greater  care,  because  they  afford  an  ex- 
planation of  the  changes  which  take  place  in  the  glottis  during  the  production  of  the  voice. 
The  Aryteno-epiglottid  Ligament. — This  ligament  {b,  figs.  176,  177)  is  constituted  by 
some  radiated  ligamentous  fibres  contained  within  the  aryteno-epiglottid  fold  of  mucous 


THE   LARYNX.  427 

membrane,  and  which  pass  from  the  anterior  surface  of  the  arytenoid  cartilage  to  the 
corresponding  margin  of  the  epiglottis.  In  some  animals,  this  ligament  is  replaced  by 
muscular  fibres. 

The  Thyro-arytenoid  Ligaments,  or  Chorda  Vocales. — Although  there  is  no  immediate 
relation  between  the  thyroid  and  the  arytenoid  cartilages,  they  are  united  by  four  very 
important  ligaments,  named  the  chorda  vocales,  which  require  a  special  description. 

The  chorda  vocales  are  also  called  the  vocal  bands,  the  ligaments  of  Ferrein,  or  the  thy- 
ro-arytenoid ligaments,  because  tliey  have  a  ligamentous  appearance,  and  extend  from 
the  retreating  angle  of  the  thyroid  cartilage  to  the  arytenoid  cartilages. 

There  are  two  vocal  cords  on  each  side,  a  superior  (s,  Jigs.  176, 178)  and  an  inferior  (r) , 
the  space  between  them  is  called  the  ventricle  of  the  larynx  (v),  and  the  interval  between 
the  cords  of  the  right  and  left  sides  is  called  the  glottis  {o,Jig.  178).*  I  shall  speak  of 
these  parts  again  presently. 

The  inferior  vocal  cord  (r,  Jig.  176)  is  much  stronger  than  the  superior,  and  has  the  form 
of  a  rounded  fibrous  cord,  stretched  horizontally  from  the  retreating  y.    j^g 

angle  of  the  thjToid  cartilage  to  the  anterior  process  of  the  arytenoid 
cartilage.  It  is  free  in  all  directions,  excepting  on  the  outside,  where 
it  is  in  contact  with  the  thyro-arytenoid  muscle.  Its  free  portion  is 
covered  by  the  mucous  membrane  of  the  larynx,  which  adheres  inti- 
mately to  it,  and  is  so  thin  that  the  white  colour  of  the  cord  can  be 
seen  through  it.  This  vocal  cord  is  thinner  than  it  appears  at  first 
sight,  the  projection  which  it  forms  being,  in  a  great  measure,  due 
to  the  thyro-arytenoid  muscle.  Its  structure  is  entirely  ligamentous, 
and  consists  of  parallel  fibres,  running  from  before  backward,  and  not 
at  all  elastic,  t 

It  is  continuous  below  with  the  lateral  thjrro-cricoid  ligament  (d). 

The  superior  vocal  cord  (s)  is  smaller,  and  situated  farther  from  the 
axis  of  the  larynx  than  the  inferior  one  (see  Jig.  178),  and  extends 
from  the  middle  of  the  retreating  angle  of  the  thyroid  cartilage  to  the 
middle  of  the  anterior  surface  of  the  arytenoid  cartilage  :  like  the  inferior  cord,  it  has  a 
fasciculated  and  fibrous  appearance  ;  but  the  fasciculi  are  few  in  number,  and  are  inter- 
mixed with  a  series  of  glandular  masses.  The  superior  vocal  cord  can  only  be  distin- 
guished from  the  rest  of  the  parietes  of  the  laiynx  from  the  reflection  of  the  mucous 
membrane  below  it,  so  as  to  form  the  ventricle.  It  is  continuous  with  the  aryteno-epi- 
glottid  ligament  (Jb,  Jig.  176)  above,  without  any  line  of  demarcation. 

Muscles  of  the  Larynx. 

These  are  divided  into  the  extrinsic  and  the  intrinsic  :  the  former,  which  move  the  en- 
tire larynx,  have  been  already  described,  viz.,  the  sterno-hyoid,  omo-hyoid,  stemo-th)Toid, 
and  thyro-hyoid  ;  to  which  we  might  add  all  the  muscles  of  the  supra-hyoid  region,  and 
those  muscles  of  the  pharynx  which  have  attachments  to  the  cricoid  and  thyroid  cartilages. 

The  intrinsic  muscles  are  nine  in  number,  viz.,  four  pairs  and  one  single  muscle. 
Those  which  exist  in  pairs  are  the  crico-thyroidei,  the  crico-arytenoidei  postici,  the  cri- 
co-arytenoidei  laterales,  and  the  thyro-arytenoidei.  The  single  muscle  is  the  arjrtenoideus. 

The  Crico-thyroideus. 

.  Dissection. — This  muscle  is  completely  exposed  by  separating  the  larynx  from  the 
muscles  by  which  it  is  covered.  In  order  to  gain  a  good  view  of  the  deep  portion  of  the 
muscle,  the  lower  part  of  the  thyroid  cartilage  must  be  removed. 

The  crico-thyroideus  {a,  figs.  147, 170)  is  a  short,  thick,  triangular  muscle,  situated  on 
the  anterior  part  of  the  larynx,  on  each  side  of  the  crico-thyroid  membrane,  and  divided 
into  two  distinct  bundles.  It  is  attached  below  to  the  cricoid  cartilage  on  each  side  of 
the  median  line,  to  the  whole  of  the  anterior  surface,  and  even  to  part  of  the  lower  bor- 
der of  the  cartilage.  From  these  points  the  fleshy  fibres  radiate  in  different  directions  : 
the  internal  fibres  pass  somewhat  obliquely  upward  and  outward ;  the  middle  ones  very 
obliquely,  and  the  lower  fibres  horizontally  outward,  to  the  lower  border  of  the  thyroid 
cartilage  (excepting  to  its  middle  portion),  and  to  the  lower  margin  of  the  corresponding 
lesser  cornu.  The  greatest  number  of  fibres  are  inserted  into  the  posterior  surface  of 
the  thyroid  cartilage  ;  some  of  them  are  continuous  with  the  inferior  constrictor  of  the 
pharynx  (w,  Jig.  147). 

It  is  covered  by  the  sterno-thyroid  muscle  and  the  thyroid  gland,  and  it  covers  the  lat- 
eral crico-arytenoid  and  the  thyro-arytenoid  muscles.  The  inner  borders  of  the  crico- 
thyroid muscles  are  separated  from  each  other  by  a  triangular  space,  broad  above  and 
narrow  below,  in  which  the  crico-thyroid  membrane  is  visible. 

*  [In  consequence  of  the  voice  being  essentially  produced  opposite  the  inferior  cords,  they  are  termed  the 
true  vocal  cords  ;  the  superior  being-  called  the  false  vocal  cords.] 

t  [The  inferior  vocal  cords  are  certainly  composed  of  elastic  tissue,  so,  also,  are  the  thyro-hyoid  and  crico- 
thyroid ligaments ;  and,  according  to  M.  I.auth  (M'm.  de  VAcad.  Roy.  de  Med.,  1835),  the  lateral  crico-thyroid 
membranes,  the  superior  vocal  cords,  and  the  aryteno-epiglottid  ligaments  are  also  composed  of  this  tissue, 
which,  he  says,  exists  even  in  the  thyro-epiglottid,  hyo-epiglottid,  and  glosso-epiglottid  ligaments.] 


428  SPLANCHNOLOGY. 

Their  action  is  not  yet  well  determined.    By  taking  theif'feed'pmnfuponthe' cricoid 

cartilage,  it  appears  to  me  that  they  would  move  the  thyroid  cartilage  in  such  a  way  as 
to  increase  the  antero-posterior  diameter  of  the  glottis,  and  thus  act  as  tensors  of  the 
vocal  cords. 

The  Crico-arytenoideus  Posticus. 

Dissection. — This  muscle  is  exposed  by  removing  the  mucous  membrane  from  the 
posterior  surface  of  the  larynx. 

It  is  a  triangular  muscle  {g,figs.  171,  177),  situated  at  the  back  of  the  cricoid  carti- 
lage. Its  fibres  arise  from  the  lateral  depression,  which  we  have  described  on  tlie  pos- 
terior surface  of  the  cartilage,  and  pass  in  different  directions  ;  the  upper  fibres  are  the 
shortest,  and  are  almost  horizontal ;  the  middle  are  oblique,  and  the  lower  are  nearly 
vertical ;  they  £dl  converge  towards  the  posterior  and  external  process  on  the  base  of 
the  arytenoid  cartilage,  behind  the  crico-arytenoideus  lateralis. 

Relations. — It  is  covered  by  the  mucous  membrane  of  the  pharynx,  to  which  it  is  very 
loosely  united,  and  it  covers  the  cricoid  cartilage. 

Action. — It  is  a  dilator  of  the  glottis.  It  carries  the  base  of  the  arytenoid  cartilage 
backward,  outward,  and  downward,  and  thus  renders  the  inferior  vocal  cord  tense 

The  Crico-arytenoideus  Lateralis. 
Fig.  177.  Dissection. — Remove  with  care  one  of  the  lateral  halves  of  the 

thyroid  cartilage  (as  in  fig.  177).     It  is  impossible  to  separate  this 
muscle  from  the  thyro-arytenoideus. 

This  is  an  oblong  muscle  (/),  situated  deeply  under  the  thyroid 
cartilage.  Its  fibres  arise  from  the  side  of  the  upper  border  of  the 
cricoid  cartilage,  in  front  of  the  crico-arytenoid  articulation  ;  from 
this  point  they  proceed  obliquely  upward  and  backward,  to  be  insert 
ed  into  the  posterior  and  external  process  of  the  arytenoid  cartilage, 
by  a  tendon  common  to  them,  and  to  the  thyro-arytenoideus.  It  is 
covered  by  the  thyroid  cartilage  and  by  the  crico-thyroid  muscle,  and 
it  covers  the  lateral  crico-thyroid  membrane  (d). 

The  Thyro-arytenoideus. 
Dissection. — The  same  as  for  the  preceding.     This  muscle  may  be 
dissected  from  the  interior  of  the  larynx,  by  removing  the  vocal  cords. 

I  describe  the  thyro-arytenoideus  and  the  crico-arytenoideus  lateralis  separately, 
merely  in  accordance  with  custom,  for  in  no  instance,  not  even  in  large  animals,  such 
as  the  ox,  have  I  ever  been  able  to  separate  them  completely.  They  have  the  same 
arytenoid  insertion  ;  their  fibres  are  situated  upon  the  same  plane,  without  any  line  of 
demarcation,  and  they  fulfil  the  same  uses.  We  naight,  therefore,  imite  them  under  the 
name  of  the  thyro-crico-arytenoideus. 

The  thyro-arytenoideus  (e)  is  a  broad  muscle,  very  thin  above  and  very  thick  be- 
low. It  arises  on  each  side  from  about  the  lower  two  thirds  of  the  retreating  angle  of 
the  thyroid  cartilage.  The  greater  number  of  its  fibres  arise  from  the  lower  part  of  the 
angle,  and  form  a  very  thick  fasciculus.  From  these  points  they  pass  horizontally  back- 
ward and  outward,  and  terminate  in  the  following  manner  :  The  thick  fasciculus  above 
mentioned  is  inserted  into  the  outer  surface  of  the  anterior  process  of  the  arytenoid  car- 
tilage, and  into  a  depression  on  the  outer  side  of  the  base  of  that  cartilage,  between  the 
two  processes.  The  upper  fibres  are  attached  to  the  outer  border  of  the  arytenoid  car- 
tilage. In  the  larger  animals,  the  upper  fibres  of  the  muscle  evidently  proceed  to  the 
epiglottis,  and  form  the  thyro-epiglottideus  of  some  authors. 

Relations. — On  the  outside  it  corresponds  with  the  thyroid  cartilage,  from  which  it  is 
separated  by  loose  and  sometimes  adipose  cellular  tissue  ;  on  the  inside  it  is  in  contact 
with  the  vocal  cords  and  the  ventricle  of  the  larynx.  The  thickest  part  of  the  muscle 
corresponds  with  the  inferior  vocal  cord,  and  is  almost  the  only  cause  of  its  projecting 
into  the  interior  of  the  larynx.  This  fasciculus  may  even  be  considered  as  contained 
within  the  substance  of  the  inferior  vocal  cord,  and  the  two  structures  are  so  closely 
adherent  that  great  care  is  required  to  separate  them.  Many  anatomists,  indeed,  have 
thought  that  the  fibres  of  the  thyro-arytenoideus  terminate  in  the  vocal  cord,  which  they 
therefore  regarded  as  the  tendon  of  the  muscle ;  but  the  cord  and  muscle  may  always  be 
completely  separated. 

Action. — It  carries  the  arytenoid  cartilage  forward,  and  would  thus  seem  to  relax  the 
inferior  vocal  cord,  as  Haller  believed  :  "  Cartilagines  guttales  (the  arytenoid)  antrosum 
ducunt,  glottidem  dilatant,  ligamentorum  glottidis  tensionem  minuunt."  {Elemcnta  Physiol., 
t.  iii.,  liv.  ix.,  p.  387.)  But  if  we  consider  the  mechanism  of  the  crico-arytenoid  articula- 
tions, and  the  mode  of  insertion  of  the  thyro-arytenoid  muscles  into  the  outer  side  of 
the  bases  of  the  arytenoid  cartilages,  we  shall  perceive  that,  at  the  same  time  that  these 
cartilages  are  carried  forward,  they  undergo  a  partial  rotatory  movement,  by  which  their 
anterior  processes  are  turned  inward.    The  ligaments  of  the  glottis  are,  therefore,  ren- 


THE  LARYNX.  429 

dered  tense,  and  approximated  towards  each  other.  This  movement  may  be  carried  to 
such  an  extent  that  the  anterior  processes  may  touch,  and  the  antero-posterior  diameter 
of  the  glottis  be  diminished  accordingly.* 

The  thyro-arytenoideus  is,  then,  both  a  tensor  and  a  constrictor  of  the  glottis.  This, 
moreover,  was  the  opinion  of  both  Cowper  and  Albinus,  but  Hedler  attempted  to  re- 
fute it.t 

The  sudden  action  of  the  thyro-arytenoid  muscle,  pressing  upon  the  ventricle  of  the 
larynx,  may  expel  any  mucus  collected  within  it. 

The  Arytenoideus. 

Dissection. — Remove  the  mucous  membrane  and  glandular  masses  which  cover  it  be- 
hind.    Detach  it  along  one  of  its  borders,  so  as  to  be  enabled  to  examine  its  thickness. 

The  arytenoideus  {a,  fig.  171)  is  a  single,  short,  thick,  trapezoid  muscle,  situated  be- 
hind the  arytenoid  cartilages,  and  filling  up  the  concavity  on  their  posterior  surfaces,  as 
well  as  the  interval  between  them.  It  arises  from  the  whole  length  of  the  outer  border 
of  the  right  arytenoid  cartilage,  and  is  inserted  into  the  corresponding  part  of  the  left. 
Some  of  the  fibres  arise  from  the  upper  border  of  the  cricoid  cartilage.  The  fibres  have 
a  triple  direction,  and  form  three  layers,  which  have  been  regarded  as  so  many  distinct 
muscles. 

The  two  more  superficial  layers  are  oblique,  and  cross  each  other,  one  passing  from 
the  base  of  the  right  arytenoid  cartilage  to  the  apex  of  the  left,  and  the  other  following 
the  opposite  direction ;  they  constitute  the  arytenoideus  ohliquus  of  Albinus  :  both  of  these 
layers  are  thin. 

The  third  and  deepest  layer  is  very  thick ;  it  is  composed  of  transverse  fibres,  and 
forms  the  arytenoideus  transversus  of  Albinus. 

None  of  the  fibres  reach  the  comicula.  Under  the  name  of  the  aryteno-epiglottideus, 
muscular  fibres  have  been  described,  extending  from  the  arytenoid  muscle  to  the  mar- 
gins of  the  epiglottis.  Some  fibres  of  the  arytenoideus  are  also  said  to  be  continuous 
with  the  thyro-arytenoideus. 

Relations. — Behind,  with  the  mucous  membrane  and  some  glandular  masses,  which  ad- 
here to  the  muscle  by  means  of  loose  cellular  tissue  ;  in  front  it  is  in  relation  with  the 
posterior  surface  of  the  arytenoid  cartilages,  and  in  the  interval  between  them  with  a 
thin  fibrous  membrane,  extending  from  the  upper  border  of  the  cricoid  cartilage  to  the 
whole  extent  of  the  inner  borders  of  the  arytenoid  cartilages. 

Action. — It  would  appear,  at  first  sight,  that  this  muscle  must  forcibly  approximate  the 
two  arytenoid  cartilages,  and  therefore  constrict  the  glottis  ;t  but  if  we  remember  that 
it  is  attached  to  the  outer  borders  of  these  cartilages,  we  shall  understand  that,  besides 
drawing  them  together,  it  must  produce  in  them  such  a  movement  as  will  carry  their  an- 
terior processes  outward,  and  stretch  the  vocal  cords,  but,  at  the  same  time,  separate  them 
from  each  other.  And  if  we  call  to  mind  that  the  th3TO-arytenoideus  occasions  an  ex- 
actly opposite  movement,  it  will  be  understood  that  the  simultaneous  action  of  the  two 
muscles  must  produce  tension  of  the  cords,  and,  at  the  same  time,  fix  the  processes. 

Having  thus  obtained  a  knowledge  of  the  cartilages  of  the  larynx,  the  articulations  by 
which  they  are  united,  and  the  muscles  which  move  them,  we  shall  now  proceed  to  give 
a  general  description  of  this  organ. 

The  Larynx  in  general. 

The  larynx,  the  general  position  of  which  has  been  already  described,  presents  certain 
diflferences  in  its  dimensions,  depending  either  upon  the  individual,  upon  sex,  or  upon  age. 
These  differences  affect  both  the  whole  of  the  larynx  and  its  constituent  parts.  Thus, 
the  larynx  of  the  female  may  always  be  distinguished  from  that  of  the  male  by  being 
smaller,  i.  e.,  about  two  thirds  the  size  of  the  male  larynx  ;  and  by  the  angles  and  pro- 
cesses of  its  cartilages  being  less  prominent,  and  their  depressions  less  marked.  These 
differences  are  connected  with  the  characters  of  the  voice,  and  affect  principally  the  di- 
mensions of  the  glottis. 

The  individual  differences  in  the  size  of  the  larynx  have  not  been  thoroughly  examined. 
The  differences  depending  on  age  will  be  noticed  when  speaking  of  its  development. 

The  larynx  presents  for  our  consideration  an  external  and  an  internal  surface. 

The  External  Surface  of  the  Larynx — Anterior  Region  {fig.  170). — In  the  median  line  we 
observe  a  vertical  ridge,  formed  by  the  angle  of  the  thyroid  cartilage  ;  beneath  this  the 
crico-thyroid  membrane,  and  still  lower  the  convexity  of  the  cricoid  cartilage. 

On  the  sides  we  find  the  oblique  leuninae  of  the  thyroid  cartilage,  a  portion  of  the  cri- 
coid covered  by  the  crico-thyroid  muscle,  and  the  thyro-cricoid  articulation. 

Sub-cutaneous  in  the  median  line,  where  it  is  only  separated  from  the  skin  by  the  linea 
alba  of  the  neck,  the  external  surface  of  the  larynx  is  covered  on  each  side  by  the  mus- 
cles of  the  sub-hyoid  region,  the  inferior  constrictor  of  the  pharynx,  and  the  thyroid  gland. 

*  [The  effect  of  this  will  be,  as  stated  by  Haller,  to  relax  the  vocal  cords,  which  is  considered  by  the  latest 
observers  to  be  the  action  of  these  muscles.] 

■t  Loc.  cit.  "  Cum  magui  viri  glottidem  dixerint  ab  istis  musculis  arctari,  experimento  facto  diducere  didici. 
Neque  potest  ille  ad  latus  cartilaginis  arytsenoidse  musculus  terminari  xjuin  earn  rimam  diducat." 

t  [When  acting  together  with  the  lateral  crico-thyroid  muscles,  this  is  certainly  their  action.] 


430  SPLANCHNOLOGY. 

The  superficial  position  of  the  surface  enables  us  to  examine  its  different  parts  through 
the  integuments,  and  renders  it  liable  to  wounds.  Its  still  greater  proximity  to  the  skin 
in  the  median  line  has  suggested  the  operation  of  laiyngotomy. 

Posterior  Region  {figs.  141,  171). — In  the  median  line  we  observe  a  prominence  like  a 
small  barrel,  on  either  side  of  which  the  thyroid  cartilage  projects.  This  prominence  is 
formed  by  the  back  of  the  cricoid,  and  by  the  arytenoid  cartilages,  the  expanded  portion 
corresponding  with  the  bases  of  the  latter,  which  are  covered  by  folds  of  a  pale  mucous 
membrane.  Under  this  membrane  we  find,  proceeding  from  above  downward,  the  ary- 
tenoideus  muscle,  the  vertical  ridge  of  the  cricoid  cartilage,  the  crico-arytenoidei  posti- 
ci,  and  the  crico-arytenoid  articulations. 

On  each  side  of  the  barrel-shaped  prominence  is  a  deep  angular  groove,  formed  by  the 
meeting  of  two  flat  surfaces,  which  are  separated  above,  but  approximated  below  ;  along 
these  grooves  it  is  supposed  that  liquids  flow  during  deglutition.  The  external  wall  of 
each  groove  is  formed  by  the  posterior  surface  of  the  thyroid  cartilage,  the  os  hyoides, 
and  the  thyro-hyoid  membrane.  The  internal  wall  is  formed  by  the  upper  and  lateral  part 
of  the  barrel-shaped  prominence.  The  grooves  are  lined  by  a  closely-adherent  nmcous 
membrane  ;  and  it  should  be  observed,  that  they  exist  only  on  a  level  with  the  aryte- 
noid cartilages,  and,  consequently,  in  this  region  alone  is  the  larynx  protected  by  the 
thyroid  cartSage,  the  posterior  borders  of  which  rest  upon  the  vertebral  column.  The 
back  of  the  cricoid  cartilage  is  on  a  level  with  the  posterior  borders  of  the  thyroid  {fig. 
174),  and,  like  them,  rests  upon  the  vertebral  colunm. 

The  Internal  Surface  of  the  Larynx. — The  internal  surface  of  the  larynx  does  not  cor- 
respond, either  in  shape  or  dimensions,  with  its  outer  surface  ;  and  this  depends  princi- 
pally on  the  fact  that  the  retreating  angle  of  the  th)T:oid  is  the  only  part  of  that  cartilage 
which  enters  into  the  formation  of  the  laryngeal  cavity,  the  lateral  laminae  being  alto- 
gether unconcerned  in  it. 

Cylindrical  below,  where  it  is  formed  by  the  cricoid  cartilage,  the  cavity  of  the  larynx 
is  prismatic  and  triangular  above,  where  it  is  constituted  by  the  epiglottis  in  front,  the 
arytenoid  cartilages  and  the  arjrtenoid  muscle  behind,  and  on  the  sides  by  the  two  mu- 
cous folds  which  extend  from  the  margins  of  the  epiglottis  to  the  arytenoid  cartilages. 
The  dimensions  of  the  lower  of  these  two  portions  of  the  laryngeal  cavity  undergo  no 
change,  always  remaining  the  same  as  those  of  the  cricoid  cartilage  ;  while  the  upper, 
on  the  contrary,  which  is  broadest  in  front,  varies  much  in  size,  in  consequence  of  the 
mobility  of  the  epiglottis  and  the  arytenoid  cartilages.  Between  these  two  portions,  and 
about  the  middle  of  the  larynx,  a  fissure  exists,  which  is  narrower  than  the  rest  of  the 
cavity,  and  oblong  from  before  backward  ;  this  is  the  glottis,  or  vocal  apparatus,  properly 
so  called.  It  can  be  seen  without  any  dissection  by  looking  down  into  the  larynx  {fig. 
178),  and  requires  a  very  particular  description. 

The  Glottis,  or  Vocal  Apparatus. — The  glottis  (yXwrrif,  from  y^uaaT),  the  tongue),  fre- 
quently confounded  with  the  superior  orifice  of  the  larynx,*  is  a  trian- 
gular opening  or  fissure  {o,fig.  178)  {rima),  elongated  from  before 
backward,  and  included  between  the  vocal  cords  of  the  right  and 
left  sides.  It  represents  two  isosceles  triangles,  placed  one  above 
the  other,  and  having  perfectly  equal  borders,  the  base  of  each  being 
directed  backward,  and  its  apex  forward.  The  lower  isosceles  tri- 
angle is  formed  by  the  inferior  vocal  cords  (r),  and  the  upper  one  by 
the  superior  vocal  cords  (s).  The  inferior  vocal  cords  are  situated 
nearer  to  the  axis  of  the  larynx  than  the  superior,  so  that  a  vertical 
plane  let  fall  from  the  latter  would  leave  the  inferior  vocal  cords  on 
its  inner  side.  Many  authors  limit  the  term  glottis  to  the  lower  tri- 
angle. This  view  is  supported  by  the  absence  of  the  superior  vo- 
cal cords  in  a  great  number  of  animals,  the  ox  in  particular. 

Dimensions  of  the  Glottis. — The  glottis  is  the  narrowest  part  of  the  larynx,  and  hence 
the  danger  from  the  introduction  of  a  foreign  body  into  it,  and  from  the  formation  of  false 
membranes  in  this  situation.  The  only  action  of  the  intrinsic  muscles  of  the  larynx  is 
to  dilate  or  contract  the  opening  of  the  glottis.  We  have  seen  that,  with  the  exception 
of  the  crico-thyroidei,  they  are  all,  in  some  measure,  collected  round  the  crico-arytenoid 
articulation,  the  movements  of  which  determine  the  dimensions  of  the  glottis. 

The  individual  differences  which  constitute  the  tenour,  baritone,  or  bass  voices  in  sing- 
ing, depend  upon  the  size  of  the  glottis ;  to  which,  also,  must  be  attributed  the  difference 
between  the  male  and  female  voice,  and  the  change  produced  in  its  tone  at  the  time  of 
puberty.  A  deep  voice  coincides  with  a  large  glottis,  and  a  shrill  voice  with  a  small  one. 
In  the  adult  male  the  antero-posterior  diameter  of  the  glottis  is  from  ten  to  eleven  lines, 
in  the  female  it  is  only  eight  lines ;  in  the  male,  the  greatest  transverse  diameter  is  from 
three  to  four  lines ;  in  the  female,  from  two  to  three  lines. t 

*  This  error  is,  perhaps,  to  be  attributed  to  the  use  of  the  word  epiglottis,  so  much  do  words  influence  our 
ideas.  It  was  committed  even  in  Haller's  time,  who  says,  "  Etiam  hoc  (laryngis)  ostktm  non  bene  pro  glottide 
sumilur." 

t  Tliese  measurements  are  taken  at  the  level  of  the  inferior  vocal  cords ;  the  transverse  diameter  is  rather 
l(!i:L'er  opposite  the  superior  vocal  cords 


THE    LARYNX.  431 

From  these  dimensions,  it  may  be  understood  how  a  Louis  d'or  might  pass  edgewise 
through  the  glottis,  and  thus  fall  into  the  trachea.  In  a  case  of  this  kind,  most  of  those 
■who  were  called  in  consultation  rejected  the  idea  of  the  presence  of  the  coin  in  the  wind- 
pipe, because,  said  they,  the  glottis  cannot  admit  it.  The  patient  died  in  about  a  year, 
and  the  Louis  d'or  was  found  in  the  trachea. 

Ventricle  of  the  Larynx. — Between  the  superior  and  inferior  vocal  cords  of  each  siile 
there  is  a  cavity,  called  the  ventricle  or  simis  of  the  larynx  {v,figs.  176,  178) ;  it  is  oblong 
from  before  backward,  and  of  the  same  length  as  the  cords  ;  its  depth  is  determined  by 
the  interval  separating  the  cords  from  the  thjToid  cartilage,  or,  rather,  from  the  thyro- 
arytenoid muscle,  which  forms  the  bottom  of  the  corresponding  ventricle.  The  opening 
of  the  ventricle  is  somewhat  narrower  than  the  bottom,  is  elliptical  in  its  longest  diame- 
ter, and  has  admitted  the  introduction  of  a  foreign  body.  To  each  ventricle  there  is  a 
supplementary  cavity,  which  is  accurately  described  and  figured  in  the  works  of  Mor- 
gagni.*  This  cavity  resembles  in  shape  a  Phrygian  cap  ;  it  has  a  broad  base,  opening 
into  the  ventricle,  and  a  narrow  apex  ;  it  is  found  at  the  anterior  part  of  the  ventricle, 
and  is  prolonged  on  the  outer  side  of  the  superior  vocal  cord,  between  it  and  the  thyroid 
cartilage,  upon  the  side  of  the  epiglottis.  Its  dimensions  vary  much.  In  one  case  its  ver- 
tical diameter  was  six  lines,  and  it  was  divided  into  two  parts  by  a  transverse  band. 

The  Circumferences  of  the  Larynx. — The  superior  circumference  of  the  larynx  {fg.  178) 
is  much  wider  than  the  inferior,  and  presents  the  following  objects  :  the  superior  angu- 
lar border  of  the  thyroid  cartilage,  and  the  great  cornua,  in  which  it  terminates  ;  behind 
the  thjToid  cartilage,  the  epiglottis  (i) ;  and  between  the  cartilage  and  the  epiglottis,  a 
small  triangular  space,  filled  by  a  compact  fatty  mass,  which  has  been  incorrectly  descri- 
bed as  the  epiglottid  gland.  I  have  already  said  that  this  fatty  mass  is  bounded  above  by  a 
fibrous  membrane,  extending  from  the  epiglottis  to  the  posterior  surface  of  the  os  hyoides. 

Behind  the  epiglottis,  we  find  the  upper  orifice  of  the  larynx,  which  must  not  be  con- 
founded with  the  glottis  ;  it  slopes  obliquely  from  before  backward  and  from  above  down- 
ward, having  the  form  of  a  triangle,  with  its  base  directed  forward  and  its  apex  back- 
ward, consequently  in  the  opposite  direction  to  the  glottis.  This  orifice  is  formed  in 
front  by  the  free  margin  of  the  epiglottis,  which  is  slightly  notched ;  on  each  side,  by  the 
upper  part  of  the  lateral  margin  of  the  epiglottis,  and  by  the  free  edge  of  the  aryteno- 
epiglottid  fold  (b) ;  and  behind,  by  the  cornicula  laryngis,  and  by  the  summits  of  the  ary- 
tenoid cartilages  (a),  and  the  deep  notch  between  them. 

The  superior  orifice  is  the  widest  part  of  the  larynx,  and  admits  foreign  bodies  which 
cannot  pass  through  its  lower  portion.  The  epiglottis,  when  depressed,  generally  cov- 
ers it  completely,  and  may  even  overlap  it  at  the  sides. 

The  inferior  circumference  of  the  larynx  is  perfectly  circular,  is  formed  by  the  cricoid 
cartilage,  and  is  continuous  with  the  trachea. 

The  Mucous  Membrane  and  Glands  of  the  Larynx. — The  mucous  membrane  of  the  la- 
rynx is  a  continuation  of  that  of  the  mouth  and  pharynx.  The  larynx  presents  the  only 
example  in  the  body  of  an  organ,  part  of  whose  external  surface,  namely,  the  posterior, 
is  covered  with  mucous  membrane  ;  and  this  depends  upon  the  circiunstance  of  its  form- 
ing part  of  the  parietes  of  the  pharynx. 

The  mucous  membrane  is  disposed  in  the  following  manner :  From  the  base  of  the 
tongue  it  i&  reflected  upon  the  anterior  surface  of  the  epiglottis,  forming  the  three  glos- 
so-epiglottid  folds  already  described,  one  in  the  middle  and  one  on  each  side  ;  it  adheres 
pretty  closely  to  the  epiglottis,  is  reflected  over  its  free  margin,  covers  its  posterior  s«r- 
face,  and  penetrates  into  the  larynx  :  on  each  side  it  passes  from  the  epiglottis  to  the 
•arytenoid  cartilages,  and  becomes  continuous  with  the  pharyngeal  mucous  membrane, 
which  covers  the  back  of  the  larynx.  At  the  superior  orifice  of  the  larynx,  it  is  reflect- 
ed upon  itself,  to  form  the  aryteno-epiglottid  folds,  which  constitute  the  sides  of  the  su- 
pra-glottid  region  of  the  larynx ;  it  then  covers  the  superior  vocal  cord,  and  lines  the  ven- 
tricle, sending  a  prolongation  into  its  supplementary  cavity.  In  the  ventricle  it  is  re- 
markable for  its  slight  adhesion  to  the  subjacent  parts.  It  is  reflected  from  the  ventri- 
cle upon  the  inferior  vocal  cord ;  there,  as  well  as  opposite  the  superior  cord,  it  is  so 
thin  that  it  does  not  conceal  the  pearly  appearance  of  the  ligament  beneath,  to  which  it 
adheres  so  closely  that  it  is  difficult  to  separate  them.  Lastly,  it  covers  the  internal  sur- 
face of  the  cricoid  cartilage,  and  the  middle  and  lateral  crico-th)Toid  membranes. 

The  laryngeal  mucous  membrane  is  characterized  by  its  tenuity,  its  adhesion  to  the 
parts  heneath  it,  and  by  its  pale  pink  colour.!  It  is  perforated  by  the  openings  of  a  num- 
ber of  mucous  glands.    Its  extreme  sensibility,  especially  at  the  upper  orifice  and  in  the 

*  I  first  saw  this  cavity  in  a  patient  affected  with  laryngeal  phthisis,  in  whom  it  was  very  much  developed. 
I  then  examined  the  larynx  in  other  individuals,  and  found  it  to  be  constant.  I  did  not  then  know  that  Mor 
gagni  had  pointed  it  out  and  figured  it  (Advers.  i.,  Epist.  Anat.,  viii.). 

t  [The  epithelium  of  the  laryngeal  mucous  membrane  is,  in  the  greater  part  of  its  extent,  columnar  and  cil 
iated.  The  cilia  urge  the  secretion  upward  ;  according  to  Dr.  Henle,  they  extend  higher  up  in  front  than  on 
each  side  and  behind  ;  on  the  sides,  for  example,  as  high  as  the  border  of  the  superior  vocal  cords,  or  about 
two  lines  above  them,  and  in  front  upon  the  posterior  surface  of  the  epiglottis,  as  high  as  its  base  or  widest  por- 
tion. Above  these  points  the  epithelium  gradually  assumes  the  laminated  form,  like  that  in  the  mouth  and 
pharynx.] 


432  SPLANCHNOLOGY. 

supra-glottid  portion  of  the  larynx,  is  well  known.*  The  aryteno-epiglottid  folds,  which 
include  the  ligaments  of  the  same  name,  and  some  muscular  fibres  in  the  larger  animals, 
aie  remarkable  for  the  great  quantity  of  very  loose  cellular  tissue  which  they  contain  : 
this  fact  explains  their  liability  to  a  serous  infiltration,  called  oedema  of  the  glottis,  which 
proves  rapidly  fatal. 

The  Glands  of  the  Larynx. — The  glands  of  the  larynx  are  the  epiglottid  and  the  aryte- 
noid. The  thyroid  gland,  or  body,  cannot  be  considered  as  belonging  to  the  larynx ;  if 
it  belongs  to  any  organ,  it  must  be  to  the  trachea. 

The  Epiglottid  Glands. — The  name  of  epiglottid  glands  is  generally  given  to  the  fatty 
mass  already  described  as  being  situated  between  the  thyroid  cartilage  and  the  epiglot- 
tis ;  and  it  has  even  been  asserted  that  it  opens  by  special  ducts  on  the  posterior  surface 
of  the  epiglottis.  But  there  is  no  other  epiglottid  gland  besides  those  situated  in  the  sub- 
stance of  the  epiglottis,  which  is  perforated  with  innumerable  holes  for  their  reception  : 
these  small  glands  are  so  numerous,  that  Morgagni  (^Advers.,  i.,  2 ;  v.,  68)  regarded  them 
as  forming  a  single  gland ;  they  all  open  upon  the  laryngeal  surface  of  the  epiglottis  by 
very  distuict  orifices,  from  which  a  considerable  quantity  of  mucus  can  be  pressed. 

The  Arytenoid  Glands. — These  were  well  described  by  Morgagni,  who  very  properly 
considered  them  as  forming  a  single  glandular  mass,  situated  in  the  substance  of  the  ary- 
teno-epiglottid fold.  They  are  arranged  in  two  lines,  united  at  an  angle,  like  the  letter 
L;t  the  vertical  line  runs  along  the  anterior  surface  of  the  arytenoid  cartilage  and  its 
comiculum,  and  produces  a  slight  prominence,  perfectly  distinct  from  that  made  by  the 
cartilages  ;  the  liorizontal  line  is  less  prominent,  and  is  situated  in  the  superior  vocal 
cord.     The  arytenoid  glands  open  separately  upon  the  internal  surface  of  the  larynx. 

Vessels  and  Nerves. — The  arteries  are  derived  from  the  superior  thyroid,  a  branch  of 
the  external  carotid,  and  from  the  inferior  thyroid,  a  branch  of  the  subclavian.  The  veins 
enter  the  corresponding  venous  trunks.  The  lymphatic  vessels,  which  are  little  known, 
terminate  principally  in  the  glands  of  the  supra-hyoid  region,  if  we  may  judge  from  the 
frequency  of  their  inflammation  in  cases  of  acute  laryngitis,  &c. 

The  nerves  are  branches  of  the  pneumogastric,  viz.,  the  superior  and  the  inferior,  or 
recurrent  laryngeal.  The  superior  laryngeal  nerves  are  not  exclusively  distributed  to  the 
muscles  called  constrictors  of  the  glottis  (thearytenoideus  and  the  crico-thyroidei) ;  nor 
do  the  inferior  laryngeals  belong  exclusively  to  those  called  dilators  (the  crico-arytenoi- 
dei  postici  and  laterales,  and  the  thyro-arytenoidei),  as  a  celebrated  physiologist  has  af- 
firmed. (See  Nkukology. )  The  peculiar  rotatory  movement  of  the  arytenoid  cartilages 
somewhat  interferes  with  any  classification  of  these  muscles  into  dilators  and  constrictors. 
Development. — The  evolution  of  the  larynx  is  remarkable  in  this  respect,  that,  after  hav- 
ing attained  a  certain  size,  it  undergoes  no  appreciable  change  until  the  time  of  puberty. 
The  ventricles  are  as  yet  so  slightly  developed  that  their  existence  has  been  denied.  The 
prominence  of  the  os  hyoides  in  some  measure  conceals  that  of  the  larynx.  M.  Rich- 
erand  {Mem.  de  la  Societe  Med.  d' Emulation,  torn,  iii.)  has  proved  that  there  is  no  very 
remarkable  difference  between  the  larynx  of  a  child  at  three  years  of  age  and  of  one  at 
twelve.  Up  to  the  age  of  puberty  the  larynx  presents  no  trace  of  the  sexual  differences 
which  afterward  become  so  evident ;  and  to  these  anatomical  conditions  are  owing  the 
shrillness  and  uniformity  of  the  voice  in  the  youth  of  both  sexes. 

At  the  period  of  puberty,  at  the  same  time  as  the  genital  organs,  the  larynx  increases 
so  rapidly  as  to  attain  its  full  development  in  the  space  of  one  year ;  the  voice  then  loses 
ilj  uniformity,  and  acquires  its  pecidiar  timbre  and  quality,  and  then  also  the  sexual  dif- 
ferences in  the  vocal  apparatus  become  manifest. 

Is  it  from  an  unequal  development  of  the  different  parts  of  the  larynx,  or  from  want 
of  a  certain  degree  of  education,  that  the  voice  at  this  period  is  so  discordant,  especial- 
ly in  singing,  or  breaks,  as  it  is  said  1 

The  simultaneous  development  of  the  genital  organs  and  the  larynx  has  led  to  the  opin- 
ion that  they  stand  to  each  other  in  the  relation  of  cause  and  effect ;  and  observation 
has  established  that  the  vocal  apparatus  is  in  some  measure  under  the  influence  of  the 
generative  organs ;  for  in  eunuchs  the  larynx  remains  as  small  as  it  is  in  the  female. 
(M.  Dupuytren,  Mem  de  la  Soc.  Phil.,  tom.  ii.), 

At  the  age  of  puberty  the  size  of  the  glottis  is  increased  by  one  third  in  the  female, 
and  is  nearly  doubled  in  the  male.  After  puberty,  any  changes  which  the  larynx  may 
undergo  are  the  result  of  exercise,  not  of  development,  properly  so  called. 

Ossification  of  the  cartilages  of  the  larynx  is  not  always  the  effect  of  age.  I  have  seen 
it  at  the  thirtieth  year  quite  independently  of  disease.  Chronic  inflammation  of  the  la- 
rynx induces  a  premature  ossification  of  the  cartilages.  The  th)Toid  has  the  greatest 
tendency  to  this  change,  then  the  cricoid,  and,  lastly,  the  arytenoid  cartilages  :  I  have 
never  observed  it  in  the  epiglottis. 

Functions. — The  larynx  is  the  organ  of  voice.  Numerous  experiments  upon  living 
animals,  and  many  surgical  facts,  show  that  the  vocal  sound  is  produced  exclusively  in 

*  It  has  been  observed,  in  experiments  upon  animals,  and  in  introducing  the  canula  after  the  operation  of 
laryngotomy,  that  the  sensibility  of  the  mucous  membrane  beyond  the  glottis  is  much  less  acute, 
t  "  Gnomonis,  sed  obtusanguli  figuram  utervis  acervns  habet." — (Haller.) 


THE   THYROID   GLAND.  433 

the  larynx.  The  lungs,  the  bronchi,  and  the  trachea  perform,  with  regard  to  the  voice, 
the  office  of  an  elastic  conductor  of  air  capable  of  contraction  and  dilatation,  of  shorten- 
ing and  elongation.  The  thorax  acts  like  a  pair  of  bellows,  by  which  the  air  is  driven 
into  the  larynx  with  any  wished-for  degree  of  force ;  and  hence  the  quantity  of  air  pass- 
ing through  the  larynx,  and  the  rapidity  with  which  it  moves,  may  vary  to  a  very  great 
extent. 

What,  then,  is  the  mechanism  of  the  voice  1  Is  it  the  same  as  that  of  a  horn  {Dodart), 
of  a  stringed  instrument  {Fcrrein),  of  a  flute  ( Cuvier),  of  a  reed  instrument  {Biot  and  Mw- 
gendic),  or  of  a  bird-call*  (Savart)  1  Is  it  produced  by  the  vibration  of  the  tense  vocal 
cords,  or  merely  by  the  vibration  of  the  air  while  passing  through  a  narrow  opening, 
which  is  itself  incapable  of  vibrating  1  We  shall  leave  these  questions  to  the  decision 
of  physiologists.  It  is  sufficient  for  our  purpose  to  know  that  the  action  of  the  muscles 
of  the  larynx  and  the  arrangement  of  the  vocal  apparatus  are  perfectly  fitted  to  produce 
either  dilatation  or  contraction  of  the  glottis  ;  and  such  is  the  mechanism  of  this  part, 
that,  from  the  rotatory  movement  of  the  arytenoid  cartilages,  the  vocal  cords  are  always 
rendered  tense,  whatever  may  be  the  other  actions  of  the  muscles. 

The  voice  as  it  issues  from  the  larynx  is  simple,  for  the  larynx  is,  with  regard  to  the 
voice,  what  the  mouth-piece  is  in  the  flute,  or  the  reed  in  the  bassoon ;  but  during  its  pas- 
sage througli  the  vocal  tube,  composed  of  the  epiglottis,  the  pharynx,  the  isthmus  of  the 
fauces,  the  mouth,  and  the  nasal  fossae,  the  voice  becomes  modified. 

According  to  a  very  ingenious  theory  of  M.  Magendie,  the  epiglottis  resembles  those 
soft;  and  movable  valves  which  M.  Grenie  places  in  the  pipes  of  an  organ  to  enable  the 
sound  to  be  increased  without  modifying  the  tone. 

The  isthmus  of  the  fauces  resembles  the  superior  larynx  of  birds,  which  consists  of  a 
contractile  orifice  that  can  be  diminished,  and  even  closed  at  pleasure  ;  and  it  is  princi- 
pally owing  to  this  mechanism  that  the  small  glottis  of  birds  can  execute  such  an  exten- 
sive range  of  notes.  We  know,  in  fact,  that  the  tone  of  a  wind  instrument  is  reduced 
an  octave  lower  by  completely  closing  the  lower  orifice  of  the  tube,  and  that,  when  it  is 
only  partially  closed,  the  tone  is  depressed  in  proportion.  Now  the  isthmus  of  the  fau- 
ces acts  exactly  like  the  superior  larynx  of  birds.  On  watching  a  person  who  wishes 
to  utter  a  very  low  note,  we  see  that  he  depresses  and  flexes  the  head  slightly  upon  the 
neck,  so  as  to  approximate  the  chin  to  the  thorax  :  by  this  means  the  vertical  diameter 
of  the  isthmus  of  the  fauces  is  diminished,  the  larynx  being  carried  upward,  while  the 
velum  palati  is  depressed  ;  and  from  this  we  may  judge  of  the  important  part  performed 
by  the  velum  in  producing  modulations  of  the  voice. 

If  to  this  we  add  the  changes  which  may  be  effected  in  the  length  and  diameter  of  the 
pharynx  (see  Pharynx),  and  if  we  remember  that,  by  diminishing  by  one  half  the  length 
or  diameter  of  the  tube  or  body  of  a  wind  instrument,  its  tone  is  raised  one  octave,  we 
shall  be  able  to  understand  how  the  human  voice  can  execute  so  extensive  a  scale  of 
notes,  although  the  glottis  is  so  small.  The  voice  is  also  modified  while  traversing  the 
buccal  and  nasal  cavities. 

Do  the  nasal  fosscr.  favour  the  resonance  of  the  voice  1  or  does  the  air,  when  passing 
through  them,  merely  give  rise  to  certain  sounds  denominated  nasal  1  The  latter  opin- 
ion, which  is  supported  by  Mr.  Gerdy,  appears  to  me  the  most  consistent  with  facts. 
MM.  Biot  and  Magendie  had  already  correctly  observed  that  the  voice  becomes  nasal 
only  when  it  traverses  these  passages. 

The  voice  becomes  articulate  in  passing  through  the  mouth,  i.  e.,  the  vocal  sound  is 
interrupted,  and  modified  by  the  more  or  less  rapid  percussion  of  the  lips  and  tongue 
against  the  teeth  and  the  palate. 

Articulate  voice  is  very  distinct  from  speech.  Animals  which  differ  much  from  man 
in  the  conformation  of  their  vocal  organs,  the  parrot,  for  example,  may  be  made  to  artic- 
ulate ;  but  speech  is  the  peculiar  attribute  of  man,  because  he  alone  is  possessed  of  in- 
telligence. 

The  Thyroid  Gland. 

The  thyroid  gland,  or  thyroid  body,  is  a  glanduliform  organ,  the  uses  of  wnich  are  un- 
known :  it  is  situated  like  a  crescent  with  its  concavity  directed  upward,  in  front  of  the 
first  rings  of  the  trachea,  and  upon  the  sides  of  the  larynx. 

In  describing  this  organ  in  connexion  with  the  larynx,  I  follow  the  usual  custom, 
which  has  arisen  not  from  any  direct  relation  between  their  functions,  but  from  their 
contiguity  to  each  other. 

The  thyroid  body  varies  much  in  size  in  different  individuals ;  there  are  few  organs 
which  present  greater  varieties  in  this  respect. 

^  The  sexual  differences  in  the  size  of  this  organ,  like  all  those  relating  to  the  vocal  ap- 
paratus, are  very  well  marked,  but  in  an  inverse  manner,  that  is  to  say,  the  thyroid  body 
is  larger  in  the  female,  in  whom  it  forms  a  rounded  projection,  which  assists  in  making 
the  thyroid  cartilage  in  that  sex  apj)ear  still  less  prominent. 

*  A  bird-call  is  a  cavity  with  elastic  walls,  perforated  upon  the  two  opposite  sides.  Tlie  cavity  is  repre- 
■ented  by  the  ventricles,  and  the  openings  by  the  intervals  between  the  vocal  cords.  If  a  tube  capable  of 
contracting  and  dilating  be  fitted  to  such  an  instrument,  an  infinite  variety  of  sounds  may  be  produced. 

I  I  I 


484  SPLANCHNOLOGY. 

Climate,  and  more  especially  certain  qualities  in  the  water  used  as  drink,  have  a  re- 
markable influence  upon  its  size,  which,  in  many  cases  of  goitre,  is  enormous. 

These  differences  in  size  affect  either  the  whole  of  the  gland  equally,  or  only  one  lobe, 
or  occasionally  the  middle  portion  alone. 

The  iveight  of  the  thyroid  body,  which  is  about  an  ounce,  may  be  increased  to  a  pound 
and  a  half,  or  even  more. 

Form. — The  thyroid  body  is  generally  composed  of  two  lateral  lobes  or  cornua,  united 
by  a  contracted  portion,  flattened  from  before  backward,  and  called  the  isthmus.  Tlie 
varieties  in  shape  principally  affect  the  isthmus,  which  may  be  very  narrow,  long  or 
short,  regular  or  irregular,  or  entirely  absent,  or  it  may  be  as  thick  and  as  long  from 
above  downward  as  the  lobes  themselves.  I  have  seen  one  case  in  which  the  thickest 
part  of  the  thyroid  gland  was  in  the  middle,  and  the  lobes  terminated  above  in  a  very 
narrow  point. 

The  opinion  of  the  ancients,  and  which  is  also  met  with  in  Vesalius,  that  the  human 
subject  has  two  thyroid  glands,  no  doubt  arose  from  the  narrowness  or  absence  of  the 
isthmus,  or,  rather,  from  the  separation  and  complete  independence  of  the  two  lobes  in 
a  great  number  of  animals.  The  surface  of  the  thyroid  body  is  smooth  and  well  defined, 
and  sometimes  divided  into  lobules  by  superficial  furrows. 

We  shall  examine  in  succession  the  relations  of  the  middle  and  lateral  portions : 

The  middle  portion  or  isthmus  is  convex  in  froTit,  and  is  separated  from  the  skin  by  all 
the  muscles  of  the  sub-hyoid  region.  Behind,  where  it  is  concave,  it  is  in  contact  with 
the  first  rings  of  the  trachea.  Moreover,  this  middle  portion  descends  to  a  greater  or 
less  distance  in  different  subjects,  and  sometimes  so  low,  that  there  is  not  room  to  per- 
form tracheotomy  between  it  and  the  sternum. 

Each  lateral  lobe  is  convex  in  front,  and  corresponds  with  the  muscles  of  the  sub-hyoid 
region  :  in  particular,  I  ought  to  mention  the  sterno-thyroid,  by  which  it  is  directly  cov- 
ered, and  the  breadth  of  which  seems  to  be  proportioned  to  the  size  of  the  lobe  ;  in  many 
cases  of  goitre  I  have  seen  this  muscle  twice  or  three  times  as  broad  as  in  the  natural 
state.  0)1  the  inside,  each  lateral  lobe  is  concave,  so  as  to  be  applied  to  the  side  of  the 
trachea  and  cricoid  cartilage,  to  the  lower  and  latter  part  of  the  thyroid  cartilage,  to  the 
lower  part  of  the  pharynx,  and  to  the  upper  part  of  the  CESophagus.  The  two  lobes,  to- 
gether with  the  middle  portion  or  isthmus,  form  a  half  or  sometimes  three  fourths  of  a 
canal,  which  embraces  all  those  parts  ;  an  extremely  important  relation,  which  explains 
how,  in  certain  goitres,  the  trachea  is  flattened  on  the  sides,  deglutition  is  impeded,  and 
true  asphyxia  by  strangulation  is  the  final  result.  Behind,  each  lateral  lobe  corresponds 
with  the  vertebral  column,  from  which  it  is  separated,  on  the  outside,  by  the  common 
carotid  artery,  the  internal  jugular  vein,  and  the  pneumogastric  and  great  sympathetic 
nerves,  which,  according  to  the  size  of  the  gland,  are  either  covered  by  it,  or  are  merely 
in  relation  with  its  outer  surface. 

The  upper  extremity  of  each  lateral  lobe  terminates  in  a  point,  and  hence  the  two- 
homed  figure  assigned  to  the  thyroid  body.  It  is  situated  on  the  inside  of  the  carotid 
artery,  in  contact  with  the  lateral  and  back  part  of  the  thyroid  cartilage,  and  sometimes 
extends  nearly  to  its  upper  border.  Its  lower  extremity  is  thick  and  rounded,  descends 
to  a  greater  or  less  distance  in  different  individuals,  and  corresponds  to  the  fifth,  sixth, 
or  seventh  rings  of  the  trachea :  it  is  situated  between  the  trachea  and  the  common  ca- 
rotid.   The  inferior  thyroid  artery  enters  the  gland  at  its  lower  extremity. 

Its  upper  border  is  concave  and  notched  in  the  middle  ;  the  superior  thyroid  arteries 
run  along  it.  A  prolongation  extends  from  this  border,  which  has  been  correctly  repre- 
sented by  Bidloo,  and  named  the  pyramid  by  Lalouette.  It  almost  always  exists ;  it 
passes  perpendicularly  upward,  either  on  the  right  or  left  side  of  the  median  line,  and 
presents  numerous  varieties  in  several  respects.  Thus  it  varies  in  its  origin,  sometimes 
arising  from  the  isthmus,  and  sometimes  from  one  of  the  lobes  at  one  side  of  the  isth- 
mus ;  also  in  its  termination,  sometimes  ending  opposite  the  notch  in  the  upper  border 
of  the  thyroid  cartilage,  sometimes  opposite  the  thyro-hyoid  membrane,  and  at  other 
times  even  on  a  level  with  the  body  of  the  os  hyoides  ;  but  always  firmly  adherent  eithei 
to  the  membrane  or  the  bone.  It  also  varies  in  its  structure  :  sometimes  it  is  a  fibrous 
cord,  and  sometimes  a  reddish  linear  band,  which  has  all  the  appearances  of  a  muscular 
fasciculus,  and  has  even  been  described  as  a  muscle ;  it  often  consists  of  a  series  of 
gremules  arranged  in  a  line  ;  sometimes,  again,  we  find,  in  the  middle,  or  at  one  end  of 
the  cord,  a  glanduliform  enlargement,  exactly  resembling  the  tissue  of  the  thjroid  gland ; 
lastly,  it  may  be  double,  or  bifurcated,  or  even  completely  wanting ;  in  which  case,  how- 
ever, there  exists  a  glanduliform  mass  of  a  certain  height.  This  prolongation,  in  which 
I  and  many  others  have  in  vain  attempted  to  find  an  excretory  duct,  is  evidently  of  a 
compact  nature.  Is  it  the  remains  of  a  fcetal  structure,  or  the  trace  of  a  normal  dispo- 
sition in  some  animals  1 

The  lower  border  of  the  thyroid  body  is  convex,  more  or  less  deeply  notched  in  the  cen- 
tre, and  is  in  contact  with  the  inferior  thyroid  arteries. 

Structure. — The  proper  tissue  of  the  thyroid  gland  is  of  a  variable  colour,  sometimes 
resembling  the  lees  of  Port  wine,  and  sometimes  of  a  yellowish  hue.    It  is  of  tolerably 


THE   UEINARY    ORGANS.  435 

nrm  consistence,  and  feels  granular.  This  organ  presents  all  the  anatomical  characters  of 
glands,  and,  like  them,  may  be  separated  by  dissection  into  glandular  grains  ;  but  with 
this  difference,  that  these  grains  communicate  with  each  other,  while,  in  ordinary  glands, 
they  are  independent.  The  communication  of  the  glandular  grains  may  be  shown  in  the 
following  manner :  if  the  tube  of  a  mercurial  injecting  apparatus  be  inserted  into  the 
thyroid  gland,  the  mercury  will  enter  into  and  distend  the  cells,  and  after  a  certain  time 
all  the  grains  will  be  injected ;  it  is  easy  to  satisfy  the  mind  that  the  mercury  is  not  in- 
filtrated into  the  cellular  tissue,  but  is  contained  in  the  tissue  of  the  gland  itself,  in  the 
centre  of  the  granulations.  The  right  and  left  lobes  do  not  conununicate,  but  all  the 
granulations  of  each  lobe  communicate  with  each  other. 

The  thyroid  gland  has,  therefore,  a  vesicular  structure  ;  and  we  have  seen  that  the 
glandular  grains  of  all  glands  are  spongy  and  porous,  and  that  the  products  of  their  secre- 
tion may  be  accumulated  in  these  pores. 

The  glandular  nature  of  the  thyroid  body  is  also  shown  by  the  viscid,  Umpid,  yellowish 
fluid  which  pervades  it  in  certain  subjects,  and  which  may  be  collected  in  sufficient 
quantity  for  chemical  analysis  ;  and  also  by  the  retention  of  this  matter  within  a  greater 
or  less  number  of  the  vesicles  when  their  orifices  of  communication  with  the  neighbour- 
ing vesicles  become  obliterated. 

But,  in  connexion  with  this  view  regarding  its  glandular  nature,  we  seek  in  vain  for  an 
excretory  duct.  If  we  examine  the  trachea  and  the  larynx,  or  lay  open  the  oesophagus, 
and  then  press  the  thyroid  gland,  we  shall  see  that  no  fluid  escapes  into  those  canals. 
It  has  been  asserted,  indeed,  that  the  excretory  duct  of  the  thyroid  gland  terminated  in 
the  foramen  ccecum  of  the  tongue,  in  the  ventricles  of  the  larynx,  or  in  the  trachea  opposite 
its  first  ring ;  but,  after  the  example  of  Santorini,  we  are  compelled  to  reject  these  fancied 
and  too  hastily  announced  discoveries. 

I  may  here  notice  the  intimate  adhesion  of  the  side  of  the  thyroid  gland  to  the  first  ring 
of  the  trachea.  This  can  be  very  well  shown  by  detaching  the  gland  from  behind  for- 
ward ;  it  is  of  a  fibrous  nature,  and  I  have  sometimes  thought  that  I  saw  a  duct  in  the 
centre  of  it,  passing  through  the  membrane  which  connects  the  trachea  with  the  cricoid 
cartilage,  though  I  have  never  been  able  satisfactorily  to  demonstrate  it. 

Still,  I  do  not  think  that  the  absence  of  an  excretory  duct  should  remove  the  thyroid 
from  among  the  glandular  organs  ;  for  I  believe  that  there  exist  in  the  body  glands  with- 
out excretory  ducts,  as  the  thymus,  the  supra-renal  capsules,  and  the  thyroid  body.  The 
secretion  of  the  gland  is  entirely  absorbed,  and  fulfils  certain  unknown  uses. 

Arteries. — The  size  and  the  number  of  the  arteries  distributed  to  the  thyroid  gland  in- 
dicate that  something  more  than  a  mere  nutritive  process  must  be  carried  on  in  it.  The 
arteries  are  sometimes  four,  sometimes  five  in  number  ;  two  superior  arise  from  the  ex- 
ternal carotid ;  two  inferior  from  the  subclavian,  and  the  fifth,  or  the  thyroid  artery  of 
Neubauer,  where  it  exists,  arises  from  the  arch  of  the  aorta. 

The  veiTis  are  proportionally  as  large  as  the  arteries,  and  form  so  considerable  a  plexus 
in  front  of  the  trachea,  as,  in  certain  cases,  to  have  prevented  the  completion  of  the 
operation  of  tracheotomy. 

The  lymphatic  vessels  terminate  in  the  cervical  lymphatic  glands. 

The  nerves  are  derived  from  the  pneumogastrics,  and  the  cervical  ganglia  of  the  sym- 
pathetic. 

A  thin  cellular  membrane  envelops  the  gland,  and  sends  very  delicate  prolongations 
into  its  substance,  where  we  find  a  very  firm  cellular  tissue,  always  destitute  of  fat. 

Development. — The  thyroid  gland  is  developed  in  two  lateral  halves,  which  are  after- 
ward united  by  a  median  portion.  It  is  not  uninteresting  to  remark,  that  this  dispo- 
sition, which  is  transitory  in  the  foetus,  represents  the  permanent  condition  of  the  gland 
in  a  great  number  of  animals.  During  intra-uterine  life  and  infancy  it  is  relatively  larger 
than  at  subsequent  periods.  Nevertheless,  the  changes  which  it  afterward  undergoes 
are  not  to  be  compared  with  those  that  occur  in  the  thymus  ;  and  we  cannot  say,  as  of 
the  latter  structure,  that  the  existence  of  the  thyroid  body  has  any  peculiar  relations 
with  foetal  life. 

Functions. — It  is  a  secreting  organ,  but  the  uses  of  its  fluid  are  not  known. 


THE  GENITO-URINARY  ORGANS. 

I  HAVE  thought  it  proper  to  describe  the  genital  and  the  urinary  organs  together,  because, 
although  their  functions  are  very  distinct,  yet  they  have  the  most  intimate  anatomical, 
physiological,  and  pathological  connexions. 

THE  URINARY  ORGANS. 
Division. — The  Kidneys  and  Ureters. — The  Bladder. — The  Supra-renal  Capsules 
The  urinary  organs  form  a  very  complex  secretory  apparatus,  consisting  of  two  secre- 
ting organs,  the  kidneys ;  of  two  provisional  reservoirs,  the  calyces  and  the  pelvis  of  each 
kidney ;  of  two  excretory  ducts,  the  ureters ;  of  a  second  and  final  reservoir,  the  bladder ; 


436  SPLANCHNOLOGY. 

and,  lastly,  of  a  second  and  final  excretory  canal,  which,  in  the  male,  is  common  to  both 
the  genital  and  the  urinary  organs,  viz.,  the  canal  of  the  urethra. 

The  Kidneys. 

The  kidneys  {ve^pol)  are  glandular  organs,  intended  to  secrete  the  urine. 

They  are  deeply  situated  {k  k,fig.  199)  in  the  lumbar  region,  hence  called  the  region  of 
the  kidneys,  on  each  side  of  the  vertebral  column,  externally  to  the  peritoneum,  which 
merely  passes  in  front  of  them ;  they  are  surrounded  by  a  great  quantity  of  fat,  and,  as 
it  were,  suspended  by  the  vessels  which  pass  into  and  emerge  from  them. 

Fixed  firmly  in  this  situation,  they  are  but  little  liable  to  displacement.  Most  of  the 
changes  in  their  position  are  congenital.  The  right  kidney  generally  descends  a  little 
lower  than  the  left,  doubtless  on  account  of  the  presence  of  the  liver.  One  of  the  kid- 
neys may  not  uncommonly  be  found  in  front  of  the  vertebral  column,  or  even  in  the. 
cavity  of  the  pelvis  ;  and  this  unusual  arrangement  may,  in  certain  cases,  render  diag- 
nosis very  obscure.*  I  have  frequently  found  the  right  kidney  in  the  corresponding  iliac 
fossa  in  females  who  had  been  in  the  habit  of  wearing  very  tight  stays.  This  displace- 
ment happens  when  the  pressure  of  the  stays  upon  the  liver  forces  the  kidney  out  of  the 
depression  in  which  it  is  lodged  in  the  lower  surface  of  that  organ. 

Number. — The  kidneys  are  two  in  number.  It  is  not  very  uncommon  to  find  only  one, 
which,  is  almost  always  formed  by  the  union  of  the  two,  by  means  of  a  transverse  portion 
crossing  in  front  of  the  vertebral  column,  and  having  its  concave  border  directed  upward. 

Sometimes  the  two  united  kidneys  are  situated  in  the  right  or  left  lumbar  region,  or 
ija  the  cavity  of  the  true  pelvis.  Cases  of  union  of  the  two  kidneys  should  be  distinguish- 
ed from  those  in  which  one  of  them  is  atrophied. 

Again,  Blasius,  Fallopius,  Gavard,  &c.,  relate  examples  of  individuals  having  three 
kidneys  ;  in  some  of  these  cases,  two  were  situated  upon  the  same  side,  in  others  the 
supernumary  kidney  was  placed  in  front  of  the  vertebral  column. 

Size. — The  kidney  is  not  subject  to  such  great  variations  in  size  as  most  other  organs. 
Its  ordinary  dimensions  are  from  three  and  a  half  to  four  inches  in  length,  two  inches  in 
breadth,  and  one  inch  in  thickness.  Its  weight  is  from  two  to  four  ounces,  t  I  have 
found  them  more  than  three  times  their  ordinary  size  in  a  diabetic  patient.  When  one 
kidney  is  atrophied,  the  other  becomes  proportionally  enlarged,  sometimes  even  to  twice 
the  usual  dimensions.  Atrophy  of  the  kidney  may  be  so  extreme  as  to  reduce  it  to  a 
drachm  and  a  half  or  two  drachms  in  weight,  and  make  it  appear  to  be  lost  among  the 
surrounding  fat ;  but  the  presence  of  this  fat  distinguishes  such  a  case  from  one  of  con- 
genital absence  of  the  kidney.t 

Density  and  Colour. — The  tissue  of  the  kidney  is  harder  than  that  of  other  glands. 
Its  fragility  accounts  for  its  laceration  by  direct  violence,  or  by  a  concussion  produced 
by  a  fall  from  a  great  height. 

Its  colour  is  that  of  the  lees  of  red  wine,  somewhat  analogous  to  that  of  the  muscular 
tissue,  but  offers  several  different  shades. 

Figure. — The  shape  of  the  kidney  may  be  well  compared  to  a  bean,  with  the  hilua 
turned  inward.     This  form  enables  us  to  consider  its  two  surfaces  and  its  circumference. 

Relations. — The  anterior  surface  of  the  kidney  is  directed  slightly  outward  ;  it  is  con- 
vex,^ and  is  covered  by  the  lumbar  colon,  but  sometimes  only  by  the  peritoneum,  the  gut 
lying  to  its  inner  side  ;  on  the  left  side  it  is  also  in  relation  with  the  spleen  and  the  great 
tuberosity  of  the  stomach,  and  on  the  right  side  with  the  liver  and  the  second  portion  of 
the  duodenum. 

The  relations  of  the  right  kidney  with  the  liver  are  more  or  less  extensive ;  sometimes 
it  is  entirely  covered  by  the  liver  ;  in  other  instances  it  is  inclined  downward,  and  has 
no  relation  with  that  organ.  The  gall-bladder  sometimes  lies  upon  the  anterior  surface 
of  the  right  kidney  through  the  whole  of  its  extent.  Lastly,  I  have  seen  the  kidney  in 
immediate  relation  with  the  parietes  of  the  abdomen,  through  which  it  could  be  easily  felt. 

As  practical  inferences  from  these  relations,  we  would  notice  the  difficulty  of  explo- 
ring the  kidneys  from  the  anterior  surface  of  the  abdomen,  on  account  of  their  deep  sit- 
uation ;  also,  the  possibility  of  an  abscess  of  the  kidney  opening  into  the  colon. 

The  posterior  surface  is  less  convex  than  the  anterior,  and  is  turned  inward  ;  it  corre- 
sponds with  the  quadratus  lumborum,  from  which  it  is  separated  by  the  anterior  layer  of 
the  fascia  of  the  transversalis  muscle  ;  with  the  diaphragm,  which  separates  it  from  the 

*  1  latplyhad  in  my  warJs  a  female  labouring  under  hectic  fever,  of  which  I  could  detect  no  cause,  either  in 
the  thorax  or  the  abdomen.  Upon  opening  the  body  after  death,  I  found  the  two  kidneys  united,  situated  in 
the  true  pelvis,  behind  the  rectum,  and  projecting  a  little  above  the  brim.  They  contained  a  large  quantity  of 
pus,  which  escaped  by  the  rectum. 

+  [According  to  M.  Raver,  the  average  weight  of  the  kidney  in  the  male  is  4i  ounces,  in  the  female  3^ 
ounces  ;  he  also  states  that  the  left  kidney  is  almost  always  larger  and  heavier  than  the  right.] 

t  1  do  not  speak  here  of  enlargement  of  the  kidneys  from  disease.  Many  examples  of  extreme  enlargement 
wall  be  found  in  my  work  on  Pathological  Anatomy,  liv.  i.,  xviii. 

()  Not  unfrequently  the  fissure  of  the  kidney  is  found  on  the  anterior  surface  of  this  organ.  In  one  case  of 
this  kind,  the  right  kidney  occupied  the  right  iliac  fossa;  it  had  two  arteries,  a  superior,  which  proceeded  di- 
rectly to  the  fissure,  and  an  inferior,  arising  from  the  angle  of  the  bifurcation  of  the  aorta,  in  front  of  the  mid' 
1  He  sacral  artery,  and  terminating  at  the  lower  extremity  of  the  kidney. 


THE   KIDNEYS. 


437 


(w6  or  three  lower  ribs ;  and  with  the  psoas,  which  intervenes  between  it  and  the  ver- 
tebral column.  These  relations  explain  the  possibility  of  exploring  the  kidney  in  the 
lumbar  region  through  the  quadratus  lumborum,  account  for  abscesses  of  the  kidney 
opening  in  the  lumbar  region,  and  for  the  escape  of  renal  calculi  in  the  same  direction, 
and  form  the  grounds  on  which  the  operation  of  nephrotomy  has  been  proposed.  It  is 
of  importance  to  remark,  that  the  relations  of  the  kidneys  with  the  ribs  are  variable  in 
extent,  and  that  sometimes  they  do  not  pass  beyond  the  last  rib. 

The  circumference  of  the  kidney  presents  an  external  border,  convex,  semi-elliptical, 
and  directed  backward ;  an  internal  border,  directed  forward,  and  deeply  notched  in  the 
middle,  to  form  ih.e  fissure  of  the  kidney  (hilus  renalis,  k,fig.  179).  This  notch  is  more 
marked  behind,  where  it  corresponds  with  the  pelvis  of  the  kidney,  than  in  front,  where 
it  corresponds  with  the  renal  vein ;  it  is  from  fifteen  to  eighteen  lines  in  depth. 

If  we  separate  the  edges  of  this  fissure,  we  expose  a  deep  cavity  containing  fat,  and 
called  the  sinus  ;  in  which  are  seen  the  pelvis  of  the  kidney  (p),  the  calices  (c  c  c'),  and 
the  divisions  of  the  renal  artery  and  vein. 

The  upper  end  of  the  kidney  is  directed  inward,  and  is  more  or  less  completely  em- 
braced by  the  supra-renal  capsule  ;  it  is  generally  larger  than  the  lower  end,  which  is  di- 
rected slightly  outward,  and  projects  beyond  the  last  rib. 

Structure. — Make  a  vertical  section  of  the  kidney  from  its  convex  to  its  concave  bor- 
der. Detach  the  proper  capsule  in  the  same  direction.  Inject  the  arteries,  veins,  and 
ureter,  in  different  kidneys,  and  also  in  the  same  kidney.     Inject  also  the  uriniferous  ducts. 

The  Proper  Coat. — The  kidney  has  no  peritoneal  covering.  The  remarkable  fatty  mass 
in  which  it  is  imbedded  is  called  the  fatty  capsule  of  the  kidney.  Besides  this,  it  is  pro- 
vided with  a  proper  fibrous  coat,  the  external  surface  of  which  adheres  to  the  fatty  tis- 
sue, by  means  of  fibrous  lamellae  passing  through  it ;  its  internal  surface  is  adherent  to 
the  tissue  of  the  kidney,  through  the  medium  of  a  number  of  small  prolongations,  which 
are  very  easily  lacerated. 

The  Tissue  of  the  Kidney. — The  kidney  differs  from  other  glands,  all  of  which  present 
a  homogeneous  and  granular  texture,  in  being  Fig.  179. 

composed  of  two  substances :  one  of  these  is  ex- 
ternal, cortical,  or  glandular  {a  a) ;  the  other  inter- 
nal, medullary,  or  tubular  {b  b  b).  Some  anato- 
mists have  described  a  third  substance,  the  mam- 
millated ;  but  the  papillas  {d  d)  of  which  it  is  com- 
posed belong  to  the  tubular  substance. 

The  following  is  the  respective  arrangement 
of  these  two  substances : 

The  cortical  sabstance  forms  a  soft,  reddish, 
sometimes  yellow  layer,  of  a  granular  appear- 
ance, and  about  two  lines  in  thickness,  which 
occupies  the  surface  of  the  kidney,  and  sends 
prolongations,  in  the  form  of  pillars  or  septa, 
from  one  to  three  lines  thick,  between  the  cones 
of  the  tubular  substance. 

The  tubular  or  medullary  substance  is  redder, 
and  presents  the  appearance  of  striated  cones  or 
pyramids  (the  pyramids  of  Malpighi),  the  bases 
of  which  adhere  to  the  cortical  substance,  while 
their  free  apices  are  turned  towards  the  sinus, 
where  they  appear  like  papillae.  Bellini,  and, 
before  him,  Berenger  di  Carpi,  considered  the 
fibres  or  striae  of  the  medullary  substance  as  so  many  uriniferous  tubes  (the  tubes  of  Bel- 
lini), and  hence  the  term  tubular  substance. 

It  follows,  then,  that  the  kidney  is  divided  into  a  number  of  compartments,  correspond- 
ing to  the  number  of  cones  of  tubular  substance ;  there  are  from  ten  to  twenty  of  these 
compartments,  which  represent  the  temporary  lobules  of  the  human  foetal  kidney,  and 
the  permanent  lobules  in  the  kidneys  of  the  greater  number  of  animals,  t 

The  kidney,  therefore,  is  formed  by  the  union  of  a  greater  or  less  number  of  small  kid- 
neys, applied  together,  and  connected  within  a  common  investment.  We  shall  see,  pres- 
ently, that,  in  reference  to  the  circulation,  these  small  kidneys  are  entirely  independent 
of  each  other.  Although  the  distinction  between  the  two  substances  is  well  marked,  it 
is  easy  to  see  that  some  of  the  fibres  or  striae  of  the  tubular  structure  penetrate  the  cor- 
tical substance  in  a  flexuous  course,  and  reach  the  surface  of  the  organ.  This  fact  was 
clearly  shown  by  Ferrein,  who  considered  the  stri^  to  be  the  excretory  ducts  of  the  gran- 
ules. These  cortical  and  flexuous  portions  of  the  tubes,  which  become  straight  as  soon 
as  they  reach  the  medullary  substance,  are  termed  the  cortical  ducts,  or  the  convoluted 
tubes  of  Ferrein. 

*  This  figure  is  a  plan,  not  an  actual  representation  of  the  structure  of  the  kidney. 
+  In  some  animals  the  kidney  resembles  a  bunch  of  grapes. 


SectioDafkidoey.* 


438 


SPLANCHNOLOGY. 


Ferrein  having  examined  the  tubes  of  Bellini  under  the  microscope,  believed  that  each 

of  them  formed  a  pyramid  analogous  to  those  of  the  tubular  substance,  and  that  each  of 

these  secondary  pyramids  consisted  of  about  a  hundred  ducts  ;  hence  the  tubes  of  the 

tubular  substance  have  been  named  the  pyramids  of  Ferrein,*  in  contradisl  inction  to  the 

pyramids  of  Malpighi. 

We  shall  now  examine  the  structure  of  the  tubular  and  the  cortical  substance. 

Structure  of  the  Tubular  Substance. — The  tubular  substance,  which,  at  first  sight,  looKs 

like  muscular  tissue,  from  its  red  colour  and  arrangement  in  lines,  evidently  consists  of 

tubes  or  ducts. 

In  fact,  an  examination  under  the  simple  microscope  of  a  section  made  perpendicu- 

Fig.  180.  larly  to  the  axis  of  the  tubes,  demonstrates  the  existence 

6     \      of  a  number  of  small  openings,  each  corresponding  to  a 

tube ;  and  if,  while  the  eye  is  fixed  upon  the  section,  the 

kidney  be  compressed,  urine  will  be  seen  to  exude  from  all 

points  of  the  cut  surface.     Direct  injection  of  the  ducts,  by 

means  of  a  tube  containing  mercury,  introduced  at  hazard 

into  the  tubular  substance,  will  fill  all  the  tubes,  in  whatever 

direction  the  instrument  may  be  directed.     The  ingenious 

experiment  performed  by  Galvani,  who  tied  the  ureters  of 

birds,  and  by  this  means  obtained  an  injection  of  the  tubes 

with  the  white  matter  of  their  urine,  leaves  no  doubt  of  the 

existence  of  these  tubes.     Lastly,  the  tubes  themselves  are 

collected  together  in  the  papillae,  and  open  either  over  their 

entire  surface,  or  in  a  small  depression  which  sometimes 

exists  at  their  summits. 

Structure  of  the  Cortical  Substance. — The  cortical  sub- 
stance is  tubular  and  granular.  The  granules  are  regularly 
disposed  around  the  convoluted  tubes  of  Ferrein.  t 

On  examining  a  thin  slice  of  uninjected  kidney  by  the 
simple  microscope,  we  perceive  a  great  number  of  oval  and 
spheroidal  granules  {c",fig.  180),  the  acini  of  Malpighi,  which 
may  be  separated  from  each  other  by  maceration  ;  and 
those  granules  which  have  been  cut  through  present  that 
spongy  appearance,  resembling  the  pith  of  the  rush,  which 
seems  to  belong  to  all  glands.  When  the  section  is  verti- 
cal, these  corpuscles  are  seen  appended  to  the  tubes  of 
Ferrein,  like  grapes  upon  their  stalk. <J 

Vessels  and  Nerves. — The  renal  artery  is  remarkable  for 
its  enormous  size,  in  proportion  to  that  of  the  kidney,  for  its  origin  from  the  aorta  being 
at  a  right  angle,  and  for  its  shortness.  There  are  sometimes  two  or  three  renal  arteries, 
and  two  are  not  unfrequently  found  twisted  spirally  around  each  other. 

When  the  kidney  is  situated  in  the  iliac  fossa  or  in  the  pelvis,  the  renal  artery  or  ar- 
teries generally  arise  from  the  common  iliac. 

The  re7ial  vein  is  as  large  in  proportion  as  the  artery,  and  passes  in  front  of  it  into  the 
vena  cava. 
The  lymphatic  vessels  are  but  little  known. 

The  nerves  are  very  numerous,  and  are  derived  from  the  solar  plexus  ;  besides  which, 
the  lesser  splanchnic  nerve  is  distributed  directly  to  the  kidney. 

The  spermatic  nervous  plexus  is  formed  by  branches  from  the  renal  plexus,  and  this 
may  explain  the  close  sympathy  between  the  testicle  and  the  kidney.  The  great  num- 
ber of  ganglionic  nerves  distributed  to  the  kidney  may  account  for  the  peculiar  charac- 
ter of  the  pain  experienced  in  this  organ. 

Injection  of  the  Renal  Vessels. — A  very  coarse  injection  thrown  into  the  artery  will  re- 
turn by  the  veins.     One  thrown  into  the  vein  will  return  by  the  ureter,  and  not  by  the 

*  See  note,  infra. 

t  According  to  Ferrein,  these  convoluted  tubes  form,  by  their  numerous  anastomoses,  a  network,  in  the 
meshes  of  which  the  granules  arc  contained. 

t  This  is  a  plan,  rather  than  an  actual  representation. 

t>  [The  urinifcrous  tubes,  commencing  at  their  orifices  upon  the  surface  of  the  papillae,  pass  up  into  the  tu- 
bular portion  of  the  kidney,  dividing  and  subdividing  dichotomously  several  times  {a,  fig.  180),  so  as  to  consti- 
tute fasciculi  of  straight  and  radiating  tubes  :  these  are  the  pyramids  of  Ferrein,  a  considerable  number  of 
which  are  united  to  form  one  of  the  pyramids  of  Malpighi  (b,fig.  179).  At  the  base  of  the  latter  the  fasciculi 
spread  out,  and  the  straight  tubes  become  the  convoluted  tubes  of  the  cortical  substance  (fig.  180). 

In  the  human  kidney,  the  tubuli  uriniferi  are  said  by  Weber  to  be  of  a  nearly  uniform  diameter  throughout 
their  entire  course  (averaging  ^^  th  of  an  inch)  ;  and  all  appeared  to  him  to  end  in  loops  (b  b),  none  in  free 
and  closed  extremities  (as  at  b') :  according  to  Krause,  they  terminate  in  both  ways.  In  either  case,  however, 
they  form  a  closed  system  of  tubes,  independent  of  the  bloodvessels,  which  merely  ramify  on  their  parietes. 
They  are  lined  with  a  mucous  membrane,  continuous  with  that  on  the  papillae,  and  having  a  columnar  epi- 
thelium. 

The  acini  of  Malpighi,  or  granules  of  M.  Cruveilhier  (c"),  are  not  of  a  glandular  nature  ;  they  consist  en- 
tirely of  minute  convoluted  arteries,  which  terminate  in  the  veins,  but  have  no  direct  communication,  as  wai 
formerly  supposed,  with  the  uriniferous  tubes  ;  they  are  called  the  glomeruli.'] 


Ma^ified  sixty  timu.t 


THE   KIDNEYS.  .^^ 

artery.*  Having  filled  the  artery  with  red  injection,  the  vein  with  blue,  and  the  ureter 
with  yellow,  I  observed  the  following  facts : 

The  renal  artery  divides  into  several  branches  within  the  sinus,  where  it  is  surround- 
ed with  fat ;  these  branches  pass  between  the  calyces,  and  then  between  the  cones  of 
the  tubular  substance,  proceeding  as  far  as  the  conunencement  of  the  cortical  substance 
without  giving  off  any  smaller  branches  :  at  that  point,  however,  they  divide  and  subdi- 
vide, so  as  to  form  a  vascular  network,  the  meshes  of  which  are  quadrilateral  and  of 
different  sizes,  inscribed  within  each  other.  The  largest  of  these  meshes  embrace  the 
entire  base  of  each  pyramid ;  the  smaller  pass  in  different  directions  through  the  sub- 
stance of  the  bases. 

In  order  to  obtain  a  good  view  of  this  arrangement,  it  is  necessary  to  divide  an  inject- 
ed kidney  along  its  convex  border,  and  scrape  away  the  tubular  substance,  which  is  so 
soft  as  to  be  easily  removed.  We  shall  then  perceive  that  the  arterial  and  venous  net- 
work, corresponding  to  the  base  of  each  cone,  is  surrounded  by  a  very  thick  fibrous  sheath, 
apparently  prolonged  from  the  fibrous  coat,  which  passes  into  the  hilus.  All  the  tubular 
substance  being  thus  removed,  the  remaining  cortical  portion  of  the  kidney  presents  the 
appearance  of  a  series  of  perfectly  distinct  alveoli,  each  of  which  corresponds  to  a  cone 
of  the  tubular  substance.    A  very  beautiful  preparation  may  thus  be  made. 

It  remains  for  us  to  inquire  how  the  arteries  terminate.  A  number  of  vessels  pro- 
ceed from  the  convexity  of  the  vascular  network  above  described,  traverse  the  cortical 
substance,  become  twisted  like  tendrils  of  the  vine,  and  appear  to  terminate  in  small  red 
masses,  regularly  arranged  along  the  convoluted  tubes  of  Ferrein.  These  small  red 
masses  are  formed  by  the  penetration  of  the  injection  into  the  cavity  of  each  granule,  as 
may  be  seen  by  examining  a  section  of  the  kidney  with  a  lens.f  If  both  the  artery  and 
the  vein  be  injected  in  the  same  kidney  (and  it  is  of  importance  that  the  vein  should  be 
injected  before  the  artery,  in  order  to  prevent  a  mixture  of  the  two  injections),  we  shall 
see  that  the  matter  injected  by  the  vein  circumscribes  that  injected  by  the  artery. 

Almost  all  the  vessels  are  destined  for  the  cortical  substance,  the  tubular  substance 
scarcely  receiving  any  branches  :$  the  vessels  of  any  one  lobule  do  not  communicate 
with  those  of  the  adjacent  lobules. 

Injection  thrown  into  the  ureter  does  not  enter  the  uriniferous  ducts,  or,  at  leeist,  very 
incompletely. 

Development. — The  surface  of  the  kidney  in  the  foetus,  as  in  the  lower  animals,  is  fur- 
rowed and  lobulated.  Each  lobule  is  fonned  by  the  medullary  substance,  covered  by  a 
layer  of  the  cortical  substance.  After  birth  the  furrows  are  effaced,  and  the  surface  of 
the  kidney  becomes  plane  and  smooth. 

This  change  takes  place  during  the  first  three  years  after  birth ;  nevertheless,  the  lo- 
bular arrangement  not  unfrequently  continues  for  nine  or  ten  years,  and  even  during  the 
whole  periwi  of  life.  When  the  kidney  is  the  seat  of  disease,  and  more  particularly 
when  it  is  distended  from  an  accumulation  of  urine  within  the  calyces  and  pelvis,  the  lob- 
ular arrangement  reappears.  Each  lobule  is  then  converted  into  a  pouch,  which  is 
perfectly  distinct  from  those  in  contact  with  it.  The  kidney  is  proportionally  larger  in  the 
foetus  than  in  the  adult. 

Functicms. — The  kidneys  are  the  secreting  organs  of  the  urine.  The  urine  is  secreted 
by  the  cortical  substance,  and,  as  it  were,  filtered  by  the  tubular  substance ;  for  perfect- 
ly-formed urine  is  found  in  the  former  situation.  The  mechanism  of  this  is  not  better 
known  than  that  of  other  secretions ;  its  rapidity  is  explained  by  the  great  quantity  of 
blood  received  by  the  kidneys. 

The  Calyces,  Pelvis,  and  Ureter. 

Dissection. — Remove  the  fat  from  the  sinus,  and  study  the  arrangement  of  the  pelvis 
and  calyces  externally.     Divide  the  kidney  from  the  convex  border  towards  the  hilus. 

The  calyces  (c  c  c',  fig.  179)  are  funnels  (infundibula),  or,  rather,  small  membranous 
cylinders,  embracing  the  bases  of  the  papillae  by  one  of  their  extremities,  almost  in  the 
same  manner  as  the  corolla  of  a  flower  embraces  the  stamina  and  pistil,  and  uniting  at 
their  other  extremity  with  the  adjacent  calyces,  to  form  the  pelvis  of  the  kidney.  They 
vary  in  number  like  the  papillae,  or  even  more  so,  for  two  or  three  papillae  frequently 
open  into  the  same  calyx.  Whatever  their  number  may  be,  they  generally  unite  into 
three  trunks,  a  superior,  a  middle,  and  an  inferior,  which  correspond  to  the  three  groups 
of  lobules,  into  which  the  kidney  may  be  divided.  These  three  trunks  unite  to  form  the 
pelvis.  The  external  surface  of  the  calyces  is  in  relation  with  a  great  quantity  of  fat, 
and  with  the  divisions  of  the  renal  artery  and  vein. 

The  pelvis  (p)  is  a  small  membranous  pouch,  situated  behind  the  renal  artery  and  vein, 
opposite  the  deep  notch  in  the  posterior  border  of  the  hilus,  so  that,  when  seen  from  be- 
hind, it  projects  completely  beyond  that  fissure.    It  is  elongated  from  above  downward, 

*  [This  is  the  result  of  rupture.]  t  See  note,  suprd. 

t  [The  vessels  (c,fig.  180)  of  the  tubular  portion  nm  parallel  with  the  tubuli  from  the  cortical  substance 
to  the  papillae  ;  they  were  mistaken  by  Ruysch  fur  the  tubub  themselves,  which  were,  therefore,  supposed  by 
him  to  communicate  with  the  arteries  in  the  glomeruli.] 


440  SPLANCHNOLOGY. 

and  flattened  from  before  backward,  and  may  become  greatly  dilated  from  retention  of 
the  urine,  or  from  renal  calculi :  almost  immediately  after  its  commencement  it  becomes 
smaller,  and  takes  the  name  of  the  ureter.  In  certain  cases  it  would  appear  that  there  is 
no  pelvis,  and  that  the  ureter  succeeds  immediately  to  the  two  or  three  trunks  formed 
by  the  union  of  the  calyces.  The  pelvis  is,  therefore,  nothing  more  than  the  expanded 
or  infundibuliform  commencement  of  the  ureter. 

The  ureter  {ovpov,  urine,  u,  Jigs.  179,  181,  199)  is  the  excretory  duct  of  the  kidney, 
and  ex  ends  obliquely  from  the  pelvis  of  that  organ  to  the  inferior  fundus  {bos  fond)  of 
the  bladder.  It  is  generally  single  on  each  side,  but  sometimes  double,  and  that  under 
two  very  different  circumstances  :  for  example,  where  the  two  kidneys  are  united  into 
one,  a  double  ureter  is  almost  invariably  found  ;  and,  secondly,  when,  there  being  two 
kidneys,  one  of  them  is  divided  into  two  very  distinct  portions.  In  the  latter  case  the 
two  ureters  are  often  united  into  one,  after  a  course  of  a  few  inches.  There  is,  then,  no 
pelvis  properly  so  called,  and  the  two  ureters  may  be  regarded  as  the  prolongation  of  the 
two  trunks  of  the  calyces,  which  remain  separate  longer  than  usual. 

The  ureter  is  a  cylindrical  tube,  having  whitish,  thin,  and  extensible  parietes,  and  va- 
rying in  size  from  that  of  a  crow's  to  that  of  a  goose's  quill.  The  most  contracted  por- 
tion of  the  canal  is  that  situated  in  the  substance  of  the  parietes  of  the  bladder.  Occa- 
sionally it  presents,  at  various  parts  of  its  extent,  some  circumscribed  dilatations,  which 
seem  to  indicate  that  the  course  of  the  urine  had  been  for  a  time  arrested.  Tiiis  canal 
is  liable  to  extreme  dilatation,  when  any  obstacle  occurs  to  the  passage  of  the  urine  :  I 
have  seen  it  as  large  as  the  small  intestine. 

Each  ureter  is  directed  obliquely  downward  and  inward,  as  far  as  the  side  of  the  base 
of  the  sacrum :  from  this  point  {fig.  181)  it  passes  downward,  forward,  and  then  inward 
(Uffig.  186),  to  the  lateral  part  of  the  inferior  fundus  (a)  of  the  bladder,  where  it  enters 
between  the  muscular  and  mucous  coats,  and  passes  obliquely  for  about  ten  lines  within 
the  substance  of  that  organ,  to  one  of  the  posterior  angles  of  the  trigone,  at  which  point 
it  opens  by  an  orifice  narrower  than  the  canal  itself,  and  having  the  form  of  a  parabolic 
curve,  with  its  concavity  directed  inward. 

Relations. — In  proceeding  from  the  pelvis  of  the  kidney  to  the  base  of  the  sacrum,  the 
ureter  passes  edong  the  anterior  margin  of  the  psoas,  and  is  covered  by  the  peritoneum 
and  by  the  spermatic  vessels,  which  cross  it  very  obliquely.  The  right  ureter  is  in  rela- 
tion with  the  vena  cava  inferior,  being  situated  on  its  outer  side.  Opposite  the  base  of 
the  sacrum,  each  ureter  crosses  the  common  iliac,  and  then  the  external  iliac  artery  and 
vein  of  its  own  side.  In  the  pelvis,  the  ureter  is  applied  to  the  parietes  of  that  cavity, 
is  covered  by  the  peritoneum,  and  crosses  in  succession  the  umbilical  artery,  or  the  cord 
by  which  it  is  replaced,  the  obturator  vessels,  the  vas  deferens  (,t,fig.  181)  in  the  male,* 
and  the  upper  and  lateral  part  of  the  vagina  in  the  female.  That  portion  of  it  which  is 
contained  within  the  substance  of  the  walls  of  the  bladder  corresponds  indirectly  with 
the  neck  of  the  uterus  ;  and  this  important  relation  explains  why  carcinoma  of  the  neck 
of  the  womb  is  so  frequently  accompanied  with  retention  of  urine.  I  have  also  observ- 
ed that  the  ureters  of  all  females  who  have  died  after  delivery,  or  during  the  last  months 
of  pregnancy,  are  remarkably  dilated. 

Internal  Surface. — The  internal  surface  of  the  calyces,  pelvis,  and  ureters  is  white, 
smooth,  and  has  longitudinal  folds,  which  are  effaced  by  distension.  There  are  no 
valves,  either  at  the  opening  of  the  calyces  into  the  pelvis,  or  of  the  pelvis  into  the  ure- 
ter, or  in  any  part  of  that  canal. 

Structure. — ^The  calyces,  the  pelvis,  and  the  ureter  have  all  the  same  structure  :  they 
are  formed  by  two  membranes  ;  an  internal  membrane,  continuous  with  the  vesical  mu- 
cous membrane,  very  thin,  and  even  having  the  appearance  of  a  serous  membrane  ;  it  is 
reflected  from  the  calyces  upon  the  papillas,  and  is  prolonged  into  the  uriniferous  tubes  : 
an  external  membrane,  which  is  very  thick,  and  supposed  to  be  a  continuation  of  the  ex- 
ternal coat  of  the  kidney,  and  therefore  to  be  fibrous.  Others  regard  it  as  muscular  ;t  I 
believe  that  it  is  formed  of  a  tissue  analogous  to  the  dartos.  Some  arteries  and  veins, 
probably,  also,  some  lymphatics  and  nerves,  are  distributed  upon  the  calyces,  the  pelvis, 
and  the  ureters,  but  do  not  require  any  special  description. 

The  Bladder. 

The  Madder  {h,Jig.  181)  is  a  musculo-membranous  sack,  which  serves  as  a  reservoir 
for  the  urine. 

It  is  situated  in  the  cavity  of  the  pelvis,  upon  the  median  line,  behind  the  pubes  (6), 
and  is  retained  in  that  position  by  the  peritoneum  (m),  which  only  partially  covers  it, 
and  by  the  urachus,  a  sort  of  ligament  connecting  it  with  the  umbilicus.  These  means 
of  attachment  are  in  accordance  with  the  great  enlargement  of  which  the  organ  is  ca- 
pable ;  but  they  cannot  prevent  certain  partial  displacements,  known  as  hcrnice  of  the 
llcdde''     When  collapsed,  it  is  completely  protected  from  external  injury ;  but  when 

*  Passing  to  its  outer  side. 

^  [lu  some  quadrupeds  the  ureter  distinctly  contracts  on  applying  a  stimulus.! 


THE  BLADDER. 


441 


filled,  it  passes  above  the  osseous  girdle  in  which  it  is  contained,  and  enters  the  dilatable 
cavity  of  the  abdomen,  where  it  can  be  distended  to  the  utmost  without  inconvenience. 

Number. —  The  bladder  Fig.  181. 

is  always  single  ;  the  ex- 
amples of  double  bladder 
which  have  been  recorded 
are  cases  of  protrusion  of 
the  mucous  membrane 
through  the  separated 
muscular  fibres.  But, 
whatever  may  be  the  size 
of  these  accidental  blad- 
ders (and  I  have  seen 
them  twdce  as  large  as  the 
true  bladder  to  which  they 
were  attached),  they  may 
always  be  distinguished 
by  their  having  no  muscu- 
lar coat.  The  cases  of  de- 
ficiency of  the  bladder  are 
generally  examples  of  that 
species  of  malformation, 
in  which  the  viscus  is  open 
anteriorly,  and  is  everted, 
80  as  to  resemble  a  fungous  mass. 

Dimensions. — The  bladder  is  the  largest  of  all  the  reservoirs  of  secretion ;  but  its  ca- 
pacity varies,  from  a  number  of  circumstances  :  from  hahit — in  persons  who  are  accus- 
tomed to  retain  their  urine  for  a  considerable  period,  the  bladder  is  more  capacious  than 
in  those  who  immediately  attend  to  the  desire  to  pass  urine  ;  from  sex — thus,  in  the  fe- 
male the  bladder  is  generally  larger  than  in  the  male,  because  she  is  more  influenced  by 
the  customs  of  society ;  from  age — ^the  bladder  appears  to  be  relatively  larger  before 
than  after  birth ;  from  disease — in  consequence  of  which  it  presents  every  variety  be 
tween  a  morbid  state  of  contraction,  in  which,  from  the  contact  of  its  parietes,  it  scarce 
ly  permits  the  accumulation  of  a  spoonful  of  urine,  and  an  extreme  state  of  dilatation,  in 
which  it  can  hold  several  pints  of  that  fluid. 

Direction. — The  direction  of  the  bladder  is  determined  by  that  of  the  anterior  wall  of 
the  pelvis,  so  that  its  axis  is  oblique  from  above  downward  and  backward.  On  account 
of  this  obliquity,  a  slight  inclination  of  the  trunk  forward  makes  the  neck  of  the  bladder 
the  most  dependent  part  of  the  organ.  The  obliquity  becomes  still  greater  when  the 
distended  bladder  has  escaped  from  the  pelvis  and  entered  the  cavity  of  the  abdomen  : 
its  axis  then  exactly  corresponds  with  that  of  the  brim  of  the  pelvis,  i.  c,  it  is  directed 
from  the  umbilicus  to  the  lower  part  of  the  curvature  of  the  sacrum.  It  has  been  said, 
since  the  time  of  Celsus,  that  the  upper  part  of  the  bladder  is  a  little  inclined  to  the  left 
side,  but  I  have  not  observed  this. 

Shape. — The  bladder  is  ovoid,  the  great  end  being  directed  downward  and  the  smaller 
upward.  Its  shape  differs  according  to  age  and  sex,  and  in  different  individuals.  The 
sexual  differences  are  not  congenital ;  they  seem  to  result  from  the  pressure  to  which 
the  female  bladder  is  subjected  during  pregnancy ;  but  the  transverse  enlargement  and 
the  vertical  shortening  of  the  bladder  in  a  female  who  has  borne  children  are  not  so 
well  marked  as  is  generally  said. 

Relations. — In  determining  these,  the  bladder  is  divided  into  the  fundus,  which  is  the 
highest  and  the  narrowest  part ;  the  body,  or  middle  portion  ;  and  the  base,  which  is  the 
lowest  and  the  broadest  portion.  It  has,  moreover,  like  all  hollow  organs,  an  external 
and  an  internal  surface. 

The  external  surface  of  the  bladder  is  convex,  and  presents  six  regions  for  our  con- 
sideration, the  relations  of  which  we  shall  now  study,  both  in  the  collapsed  and  distend- 
ed condition  of  the  viscus.  The  anterior  region,  not  covered  by  the  peritoneum,  is  in 
relation  with  the  symphysis  and  bodies  of  the  ossa  pubis,  and  with  the  internal  obtura- 
tor muscles,  with  which  parts  it  is  connected  by  a  very  loose  serous  cellular  tissue,  in 
stout  persons  more  or  less  loaded  with  fat.  Some  fibrous  bundles  pass  from  the  lower 
part  of  this  region,  and  are  attached  to  the  sides  of  the  symphysis  ;  they  are  called  the 
anterior  ligaments  of  the  bladder,  and  are  traversed  by  numerous  veins ;  they  are  a  de- 
pendance  of  the  superior  pelvic  aponeurosis  (q,fig.  181).  (Vide  Aponeurologv.)  In 
the  female,  on  account  of  the  absence  of  the  prostate,  the  anterior  region  of  the  bladder 
passes  below  the  symphysis,  and  advantage  may  be  taken  of  this  circumstance  in  the 
extraction  of  calculi.  When  the  bladder  is  full,  its  anterior  region  corresponds  imme- 
diately with  the  parietes  of  the  abdomen,  and  sometimes  rises  as  high  as  the  umbilicus. 
The  practical  conclusions  to  be  derived  from  these  relations  refer  to  the  examination 
of  the  bladder  in  the  hypogastrium,  to  puncture  of  this  organ  in  the  same  situation,  to 

Kkk 


i 


442  SPLANCHNOLdGT. 

the  high  operation  for  stone,  to  the  operation  of  dividing  the  symphysis,  and,  lastly,  to 
ruptures  of  the  bladder  in  consequence  of  fracture  of  the  pubes.* 

The  posterior  region  of  the  bladder  is  covered  by  the  peritoneum  (u)  throughout  the 
whole  of  its  extent ;  in  the  male  it  corresponds  with  the  rectum  (o),  and  in  the  female 
with  the  uterus.  Some  convolutions  of  the  small  intestine  almost  always  intervene  be- 
tween the  bladder  and  those  parts. 

The  lateral  regimis  are  also  covered  by  the  peritoneum ;  and  passing  upon  each  of 
them  are  found  the  umbilical  artery  in  the  foetus,  and  subsequently  the  hgament  by  which 
it  is  replaced,  and  also  the  vas  deferens  (0  in  the  male.  When  the  bladder  is  perfectly 
contracted,  there  is  some  distance  between  it  and  that  vessel  and  duct  on  either  side. 

The  relations  of  the  hwer  region  or  base  of  the  bladder,  which  are  all  very  important, 
differ  in  the  two  sexes. 

In  the  male  it  corresponds  to  the  rectum,  from  which  it  is  separated  on  either  side  in 
front  by  the  vesicula  seminalis  («)  and  the  vas  deferens  {t).  The  only  part  in  direct  re- 
lation with  the  rectum  is,  therefore,  the  triangular  space  {fig.  186)  comprised  between 
the  vesiculae  (s  s')  and  the  vaisa  deferentia  (J,  I')  of  the  two  sides.  It  is  of  importance  to 
remark,  that  the  peritoneum,  where  it  is  reflected  from  the  rectum  upon  the  posterior 
region  of  the  bladder,  forms  a  more  or  less  deep  cul-de-sac  in  the  middle,  and  two  small 
folds  on  the  sides,  which  have  been  improperly  named  the  posterior  ligaments  of  the  blad- 
der. When  the  bladder  is  much  contracted,  the  peritoneum  covers  the  whole  of  the 
space  between  the  vesiculae  and  the  vasa  deferentia  ;  so  that,  properly  speaking,  there 
is  no  immediate  relation  between  that  organ  and  the  rectum.  On  the  other  hand,  when 
it  is  distended,  it  becomes  much  enlarged  posteriorly,  and  has  much  more  extensive  re- 
lations with  the  rectum,  t  It  is  important,  also,  to  remark,  that  the  peritoneum  is  very 
loosely  united  to  the  base  of  the  bladder,  so  that  they  can  be  easily  separated  whenever 
it  is  desirable  to  reach  the  bladder  from  the  rectum.  On  each  side  of  the  rectum  the 
base  of  the  bladder  corresponds  with  the  cellular  tissue  of  the  pelvis.  The  superior  pel- 
vic fascia  and  the  levatores  ani  are  attached  to  and  embrace  the  sides  of  the  base. 

In  the  female,  the  base  of  the  bladder  corresponds  not  only  with  the  vagina,  but  with 
the  lower  half  of  the  neck  of  the  uterus  ;  it  adheres  very  intimately  to  the  former,  but 
loosely  to  the  latter. 

As  practical  consequences  of  these  relations,  I  would  point  out  the  following  :  In  the 
male,  the  occurrence  of  recto-vesical  fistulae,  the  possibility  of  exploring  the  bladder  by 
the  rectum,  and  of  operating  upon  it  in  the  same  situation.  In  the  female,  the  capability 
of  examining  the  bladder  by  the  vagina,  of  puncturing  it,  and  of  performing  lithotomy 
through  the  same  part ;  the  occurrence  of  vesico- vaginal  fistulae,  and  the  frequency  with 
which  carcinoma  of  the  bladder  follows  the  same  affection  of  the  cervix  uteri. 

Summit,  or  Fundus. — This  part  of  the  bladder  is  directed  forward  and  upward,  and  is 
covered  by  peritoneum.  The  urachus  is  a  sort  of  cord,  having  a  muscular  appearance, 
and  stretching  from  the  summit  of  the  bladder  to  the  umbilicus,  into  which  it  appears  to 
enter.  This  cord  adheres  tolerably  firmly  to  the  peritoneum,^  which  forms  a  falciform 
fold  over  it,  and  may  be  drawn  down  with  it  when  it  is  displaced.  In  a  case  of  hyper- 
trophy of  the  bladder,  I  found  the  cord  it^lf  hypertrophied,  and  continuous  with  the  longi- 
tudinal muscular  fibres  of  the  bladder,  almost  in  the  same  way  as  the  round  ligament  of  the 
uterus  with  the  fibres  of  that  organ.  The  urachus  is  merely  the  vestige  of  a  canal  which  ex- 
ists in  the  foetus  of  quadrupeds,  and,  according  to  several  authors,  in  the  human  foetus  also. 

There  have  been  many  discussions  upon  this  subject,  some  stating  that  the  cord  is 
hollow,  others  that  it  is  solid.  I  have  always  found  it  solid,  both  in  the  adult  and  in  the 
foetus.  In  one  case  I  found  a  small  concretion  in  it,  which  I  regret  not  having  submit- 
ted to  chemical  analysis.  It  is  very  common  to  find  the  urachus  large  at  its  origin,  and 
becoming  narrower  after  a  course  of  two  or  three  inches,  and  then  blending  with  the 
cord,  which  takes  the  place  of  the  left  umbilical  artery  ;  at  other  times  it  expands  into 
cellular  tissue,  and  the  filaments  resulting  from  its  division  proceed,  some  to  the  umbili- 
cus, and  others  to  the  cords  which  represent  the  obliterated  umbihcal  arteries. 

In  the  erect  posture,  the  weight  of  the  intestines  presses  on  the  summit  of  the  bladder, 
which  is  thus  pushed  downward ;  and  hence  the  necessity  for  placing  the  patient,  during 
certain  operations,  especially  that  of  lithotrity,  in  the  horizontal  position,  or  even  on  an 
inclined  plane,  so  arranged  that  the  pelvis  is  more  elevated  than  the  shoulders. 

The  internal  surface  of  the  bladder  is  covered  by  a  mucous  membrane,  hke  all  cavities 
which  conununicate  with  the  exterior ;  and  is  remarkable  for  certain  folds  or  wrinkles, 
which  are  effaced  by  distension,  and  for  the  reticular  ridges  formed  by  the  fasciculi  of 
its  muscular  coat ;  these  are  sometimes  very  highly  developed,  and,  in  certain  cases, 

*  It  has  even  been  proposed  to  puncture  the  bladder  through  the  symphysis,  by  means  of  a  flattened  tro- 
car ;  but  the  difficulty  of  coming  exactly  upon  the  symphysis  will  probably  prereut  the  execution  of  this  plan. 

t  The  varieties  in  the  depth  of  the  cul-de-sac  formed  by  the  reflected  peritoneum,  pointed  out  by  modern 
•nrgeons,  appear  to  me  to  be  explicable  by  the  difference  in  size  of  the  bladders  examined.  The  arrange- 
ment of  the  peritoneum  seems  to  me  to  be  exactly  the  same  in  all  subjects. 

t  It  would  appear,  from  a  fact  which  I  have  observed,  that  the  bladder  cannot  be  dragged  into  either  inter- 
nal abdominal  rin^,  excepting  after  the  urachus  ;  this  being  itself  drawn  down  by  the  peritoneum,  with  whick 
it  is  closely  united. 


THE    BLADDER. 


443 


are  so  large,  that  they  form  pillars,  which  project  into  the  interior  of  the  bladder.  The 
mucous  membrane  not  unfrequently  becomes  insinuated  between  these  columns,  so  as 
to  form  cells,  or  what  is  termed  sacculated  bladder.  The  base  of  the  bladder  presents 
three  openings,  viz.,  the  orifices  of  the  two  ureters  (r  r,fig.  182),  and  the  opening  into 
the  urethra.  These  three  openings  occupy  the  angles  of  an  equilateral  triangle  ("  coUi- 
cula  ab  ureteribus  ad  urethram  producta,"  Holler),  the  sur-  pig.  182. 

face  of  which  is  smooth  and  white,  and  is  always  devoid  of 
wrinkles  or  columns.  This  is  the  trigone  of  the  bladder,  or 
trigone  of  Lieutaud,  which  has  been  supposed  to  possess  a 
pecuhar  degree  of  sensibihty.  The  posterior  border  (r  r)  of 
this  trigone  is  more  or  less  prominent  in  different  individ- 
uals, and  is  formed  by  a  line  stretching  between  the  orifices 
of  the  two  ureters ;  this  prominence  is  prolonged  outward 
on  each  side  by  the  portion  of  the  ureter  which  lies  in  tl>e 
parietes  of  the  bladder.  It  has  been  stated  incorrectly,  that 
the  trigone  is  formed  by  the  projection  of  the  prostate,  for  it 
exists  in  females  as  well  as  in  males,  though  it  is  less  prom- 
inent than  in  the  former.  All  that  part  of  the  base  of  the 
bladder  which  is  behind  the  trigone  is  generally  called  the 
las  fond,  ot  inferior  fundus.* 

Most  anatomists  follow  Lieutaud  in  describing,  under  the 
name  of  uvula  vesica,  a  tubercle  which  arises  from  the  low- 
er part  of  the  orifice  of  the  urethra,  and  partially  fills  up  that 
opening ;  but  it  exists  only  in  cases  of  disease,  being  the  re- 
sult of  hypertrophy  of  the  middle  portion  of  the  prostate,  de- 
scribed by  Home  as  the  middle  lobe. 

The  orifices  of  the  ureters  are  so  constructed  as  to  per- 
mit the  easy  passage  of  the  urine  into  the  bladder,  but  com- 
pletely to  oppose  its  reflux.  Their  long  oblique  course  be- 
neath the  mucous  membrane  before  opening  into  the  blad- 
der explains  this  arrangement.  The  raised  and  reflected 
portion  of  the  membrane  might  be  called  the  valve  of  the  ureter. 

The  opening  of  the  urethra,  which  is  also  called  the  neck  of 
the  bladder,  is  habitually  closed,  and,  as  it  were,  corrugated. 
Some  force  is  required  in  order  to  overcome  the  resistance 
offered  by  it ;  the  crescentic  form  which  has  been  attributed  to  it  is  not  very  evident. 

Structure. — The  bladder  has  three  coats  :  a  peritoneal,  which  is  incomplete,  a  muscu- 
lar, and  a  mucous  coat ;  these  are  connected  by  layers  of  cellular  tissue  :  it  has  also  ves- 
sels and  nerves. 

The  peritoneal  coat  covers  the  posterior  and  laterjil  regions,  and  the  inferior  fundus  of 
the  bladder.  The  anterior  region,  and  that  part  of  the  base  which  is  in  front  of  the  infe- 
rior fundus,  are  not  covered  by  it.  It  is  united  to  the  muscular  coat  by  very  loose  cellu- 
lar tissue. 

The  muscular  coat  is  formed  of  interlacing  fibres,  the  direction  of  which  it  is,  at  first 
sight,  very  diiScult  to  determine.  +  This  coat  is  very  thin,  and  does  not  form  a  continu- 
ous layer  in  enlarged  bladders  ;  but  in  small  and  contracted  bladders  it  is  continuous, 
and  consists  of  several  layers,  and  may  even  acquire  a  thickness  of  eight  or  ten  lines 
from  hypertrophy.  It  is,  then,  very  easy  to  determine  the  direction  of  the  fleshy  fibres, 
which  seem  to  form  a  number  of  layers.  The  external  layer  consists  of  longitudinal 
fibres,  all  of  which  proceed  from  the  neck  of  the  bladder,  and  expand  over  the  whole  sur- 
face of  the  organ  ;  the  next  layer  is  formed  of  circular  fibres,  some  of  which  are  irregu- 
larly interlaced,  while  the  others  are  parallel.  The  regular  circular  fibres  are  most  nu- 
merous opposite  the  inferior  fundus  of  the  bladder,  and  are  continuous  with  the  annular 
fibres  of  the  neck. 

The  irregular  circular  fibres  are  most  common  in  the  posterior  region  of  the  organ.  In 
the  situation  of  the  trigone,  the  muscular  layer  consists  of  transverse  parallel  fibres,  pla- 
ced near  each  other,  and  forming  a  perfectly  regular  plane.  The  transverse  thick  bun- 
dle stretching  between  the  orifices  of  the  ureters  has  been  regarded  by  Sir  C.  Bell  as  the 
muscle  of  the  ureters.  Its  contraction,  by  enlarging  their  orifices,  will  facilitate  the 
entrance  of  the  urine  into  the  bladder. 

The  term  sphincter  of  the  bladder  is  applied  to  a  muscular  ring,  which  is  continuous 
with  the  circular  fibres  of  the  body  of  the  bladder,  and  is  situated  at  the  opening  of  the 
urethra.  The  vagueness  and  disagreement  in  the  descriptions  of  this  sphincter  suffi- 
ciently prove  that  no  very  distinct  structure  of  the  kind  exists  at  the  neck  of  the  blad- 
der.   Winslow  describes  some  fibres  arising  from  the  ossa  pubis,  and  embracing  tie 

*  It  is  not  uncommon  to  find  the  bladder  forming  behind  the  trigone  a  deep  cul-de-sac,  which  I  have  seen 
insinuated  between  that  part  and  the  rectum.  _ 

t  [These  fibres  belong  to  the  involuntary  class,  the  microscopic  characters  of  which  are  described  in  the 
note,  p.  32.-?.] 


444  SPLANCHNOLOGY. 

sides  of  the  vesical  orifice,  as  the  sphincter  muscle,  but  they  evidently  belong  to  the  le- 
vator ani.  It  is  certain,  however,  that,  in  the  neck  of  the  bladder,  there  is  a  thin  exter- 
nal layer  of  longitudinal  muscular  fibres,  and  also  a  deep  and  very  thick  layer  formed  of 
circular  fibres  ;  both  layers  seem  to  be  continued  into  the  prostatic  portion  of  the  urethra 

The  mucous  coat  is  extremely  thin,*  of  a  whitish  colour,  and  presents  some  small  papil 
lae.  It  is  so  difficult  to  demonstrate  its  follicles,  that  their  existence  has  been  denied ; 
but,  with  a  little  attention,  they  may  always  be  found  in  the  neighbourhood  of  the  neck 
of  the  bladder,  and  upon  the  trigone.  I  have  seen  them  in  all  parts  of  the  bladder,  under 
the  form  of  vesicles,  in  certain  cases  of  disease.  The  mucous  membrane  is  moulded 
upon  all  the  ridges  of  the  muscular  coat :  it  sometimes  dips  between  the  muscular  bun- 
dles, and  forms  cells,  in  which  calculi  are  often  lodged.  Bladders  of  this  kind  are  call- 
ed sacculated,  and,  moreover,  are  almost  ,a\vf?iys  fasciculated ;  i.  e.,  the  muscular  fibres 
are  so  highly  developed  as  to  raise  up  the  mucous  membrane  into  ridges.  The  cellular 
tissue  uniting  the  muscular  and  the  mucous  coats  is  tolerably  loose,  serous,  and  extreme- 
ly delicate. 

Vessels  and  Nerves. — The  vesical  arteries  arise  either  directly  from  the  hypogastrics,  or 
from  their  branches.  They  are  variable  in  number.  The  veins  form  a  very  remarkable 
plexus  around  the  neck  of  the  bladder,  which  is  prolonged  upon  the  sides  of  the  inferior 
fundus,  and  terminates  in  the  hypogastric  veins.  The  lymphatic  vessels  are,  for  the  most 
part,  situated  between  the  muscular  and  the  peritoneal  coats,  and  terminate  in  the  hypo- 
gastric lymphatic  glands.  The  nerves  are  derived  from  the  hypogastric  plexus,  which  is 
composed  both  of  ganglionic  and  spinal  nerves  ;  and  hence  the  bladder  is  partly  subject 
to,  and  partly  beyond  the  influence  of  the  will. 

Development. — The  bladder  of  the  foetus  is  remarkable  for  the  predominance  of  its  ver- 
tical over  its  transverse  diameters,  the  latter  being  very  short.  This  fact,  added  to  the 
imperfect  development  of  the  pelvis,  explains  why  the  entire  bladder  projects  above  the 
brim  of  the  pelvis  at  this  period  of  life.  The  inferior  fundus  does  not  exist.  The  sum- 
mit is  gradually  continued  into  the  urachus,  which  is  then  much  larger  than  at  subse- 
quent periods,  and  of  which  the  bladder  appears  to  be  merely  an  expansion.  According 
to  some  authors,  the  bladder  is  relatively  larger,  and,  according  to  others,  smaller  before 
than  after  birth. 

In  the  early  periods  of  infancy,  the  bladder  retains  tht  characters  which  it  had  in  the 
foetus,  and  many  important  surgical  inferences  may,  therefore,  be  drawn  from  its  more 
extensive  relations  with  the  abdominal  parietes.  In  proportion  as  the  pelvis  is  devel- 
oped, and  also,  perhaps,  in  proportion  as  the  frequently-accumulated  urine  dilates  the 
bladder  in  its  transverse  and  antero-posterior  diameters,  this  organ  sinks  into  the  pelvic 
cavity,  and,  when  completely  developed,  presents  the  characters  already  assigned  to  it. 

The  urachus,  which,  we  have  seen,  is  converted  into  a  muscular  cord  in  the  adult,  and 
is  sometimes  lost  before  reaching  the  umbilicus,  is  much  more  developed  in  the  foetus  :  it 
may  then  be  traced  as  far  as  the  umbilicus,  and  even,  according  to  some  anatomists, 
through  the  whole  extent  of  the  umbilical  cord.  Analogy,  and  some  observations  upon 
the  human  subject,  would  seem  to  show  that  the  urachus  is  hollow  in  the  foetus.  In  the 
lower  animals  the  cavity  of  the  urachus  may  be  traced  into  a  bag  called  the  allantois, 
which  is  situated  between  the  membranes  of  the  ovum  ;  and  it  is  stated  by  several  au- 
thors, that  they  have  caused  mercury  injected  into  the  bladder  to  pass  some  distance 
(half  an  inch,  one  inch,  or  one  inch  and  a  half)  into  the  urachus,  and  even  for  a  greater 
or  less  extent  into  the  umbilical  cord. 

Moreover,  in  new-born  infants,  and  even  in  adults,  the  urine  has  been  seen  to  escape 
through  the  umbilicus  ;  but,  in  these  cases,  the  urethra  is  always  obliterated.  I  have 
already  said  that  I  have  met  with  a  calculous  concretion  within  the  substance  of  the 
urachus,  and  I  find  that  Haller  and  Harder  have  made  a  similar  observation  {arenuliB  in 
uracho  visa,).  M.  Boyer  {Traiti  d" Anatomic,  p.  477,  Splanchnoi  ogie)  says  that  he  has 
dissected  the  bladder  of  a  man  twenty-six  years  of  age,  whose  urachus  formed  a  canal 
an  inch  and  a  half  long,  and  contained  twelve  urinary  calculi  as  large  as  millet-seeds  ; 
one  of  them  was  larger,  and  resembled  a  grain  of  barley.  He  convinced  himself  that  the 
canal  which  contained  these  calculi  was  not  formed  by  a  prolongation  of  the  internal 
membrane  of  the  bladder  through  the  other  coats.  On  the  other  hand,  a  number  of  ob- 
servers (myself  among  them)  have  found  the  urachus  solid  in  the  foetus.  New  facts  are, 
therefore,  necessary  to  settle  this  anatomical  question  ;  although  it  is  very  probable  that 
the  urachus  of  the  human  subject  is  of  the  same  nature  as  that  of  animals,  but  becomes 
obliterated  at  a  much  earlier  period. 

Functions. — The  bladder  is  intended  as  a  reservoir  for  the  urine,  and  is  also  the  prin- 
cipal agent  in  its  expulsion.  The  urine  constantly  trickles,  drop  by  drop,  into  the  blad- 
der, but  cannot  flow  back  by  the  ureters,  on  account  of  the  mechanism  already  described. 
Wlien  the  bladder  is  distended,  it  occasions  a  desire  to  evacuate  its  contents,  and  the 
urine  is  then  expelled  by  the  combined  action  of  the  bladder  itself  and  the  abdominal 
muscles.     I  have  said  that  the  bladder  is  the  chief  agent  in  this  expulsion,  for,  in  cases 

*  [This  and  all  the  other  portions  of  the  genito-urinary  mucous  membrane  have  <in  epithelium,  which  ap- 
•roaches  to  the  columnar  in  character.] 


THE  SUPRA-RENAL  CAPSULES.  445 

of  retention  of  urine  from  paralysis,  or  excessive  distension  of  the  bladder,  the  most 
powerful  contractions  of  the  abdominal  muscles  are  not  sufficient  to  expel  it. 
The  Supra-renal  Capsules. 

The  supra-rend  capsules  (c  c,Jig^.  199)  are  organs  whose  use  is  unknown ;  they  are  situ- 
ated near  the  upper  end  of  the  kidneys,  and,  hke  them,  are  outside  of  the  peritoneum. 

The  proximity  of  the  kidneys  and  supra-renal  capsules  has  led  to  the  supposition  that 
there  is  some  mutual  relation  between  their  functions ;  and  hence  they  are  generally  de- 
scribed together,  though  not  on  perfectly  just  grounds.*  The  name  renes  succenturiati 
( Casserius)  is  sufficient  evidence  of  the  relation  which  has  been  supposed  to  exist  be- 
tween these  organs.  Nevertheless,  this  connexion  of  situation,  which  constitutes  the 
most  important  and  characteristic  feature  in  the  history  of  the  supra-renal  capsules,  is 
not  constant ;  and,  in  the  numerous  cases  in  which  the  kidneys  occupy  some  unusual 
position,  the  supra-renal  capsules  do  not  accompany  those  organs  in  their  displacement. 
Thus,  when  the  kidneys  are  situated  higher  than  usual,  the  capsules  are  placed  on  their 
inner  side,  and  correspond  vsith  the  renal  fissure  ;  when  the  kidneys  occupy  the  pelvic 
region,  the  capsules  undergo  not  the  slightest  change  in  their  position,  and  no  longer 
have  any  connexion  with  them. 

Number. — There  are  two  supra-renal  capsules ;  it  is  said  that  two  have  been  found  on 
each  side. 

Size. — They  vary  much  in  size  in  different  individuals  :  sometimes  they  are  so  small 
that  they  can  scarcely  be  distinguished  from  the  fat  by  which  the  kidney  is  surrounded ; 
at  other  times  they  are  very  large.  In  a  case  where  the  two  kidneys  were  very  small, 
I  found  the  supra-renal  capsules  much  larger  than  usual.  It  has  been  said  that  they  are 
larger  in  the  negro  than  in  the  Caucasian  race.  I  have  examined  two  negroes,  and  did 
not  find  them  unusually  large.  In  the  foetus  they  are  proportionally  larger  than  in  the 
adult.     I  have  found  them  very  large  in  several  females  far  advanced  in  years. 

The  two  capsules  are  not  of  the  same  size.  Eustachius  affirms  that  the  right  is 
larger  than  the  left  ;  but  I  have  generally  found  the  reverse.  Their  weight  is  about  one 
drachm. 

Form. — I  shall  follow  the  example  of  M .  Boyer,  in  comparing  these  supra-renal  capsules 
to  a  helmet,  flattened  on  its  anterior  and  posterior  surfaces,  and  embracing  the  upper 
end  of  the  kidney  by  a  narrow  and  concave  surface.  The  relations  of  its  anterior  surface 
are  different  on  the  right  and  the  left  side. 

On  the  right  side  it  is  in  relation  with  the  liver,  to  which  it  adheres  by  a  tolerably  dense 
cellular  tissue,  so  that  the  capsule  is  always  removed  in  connexion  with  that  organ. 
This  relation  between  the  liver  and  the  capsule  is  much  more  constant  and  intimate  than 
that  between  the  capsule  and  the  kidney.  A  small  depression,  already  described  as  ex- 
isting on  the  lower  surface  of  the  liver,  to  the  right  of  the  vena  cava  ascendens,  is  in- 
tended for  the  reception  of  the  capsule. 

On  the  left  side  the  capsule  is  in  immediate  relation  with  the  pancreas,  and  is  indirect- 
ly connected  with  the  spleen  and  the  great  end  of  the  stomach. 

The  posterior  surface  is  in  contact  with  the  highest  part  of  the  pillars  of  the  diaphragm, 
opposite  the  tenth  dorsal  vertebra.  The  great  splanchnic  nerves  and  the  semilunar 
ganglia  are  situated  behind,  and  on  the  inner  side  of  the  capsules,  to  which  they  send  off 
so  many  branches,  that  Duvernoy  regarded  these  organs  as  the  ganglia  of  the  renal  nerves. 

Their  convex,  thin,  and  slightly  sinuous  border,  is  directed  inward  and  upward.  Their 
concave  border  is  thick,  and  almost  always  deeply  grooved.  The  surface  of  the  capsules 
is  invested  by  a  thin  layer  of  fat,  which  it  is  extremely  difficult  to  remove,  on  account 
of  the  numerous  fibrous  and  vascular  prolongations  that  pass  into  it  from  the  capsule ; 
certain  furrows,  either  containing  vessels  or  not,  and  varying  in  depth  and  extent,  trav- 
erse the  surface  of  this  organ,  especially  in  front. 

Cavity. — It  is  still  doubtful  whether  the  supra-renal  capsules  have  a  cavity  in  their  in- 
terior, as  their  name  would  seen  to  indicate.  It  is  certain  that  in  the  greater  number 
of  subjects,  on  dividing  them  in  different  directions,  they  are  found  to  consist  of  two 
laminae  applied  to  each  other,  and  united  as  by  an  adhesive  substance,  a  sort  of  dark- 
coloured,  false  membrane  ;  and  that  these  laminaj  are  reflected  inward  opposite  the  con- 
cave border,  so  as  to  form  a  projection  like  a  cock's  comb  in  the  interior  of  the  capsule. 
The  colour  of  the  external  surface  is  yellowish,  or,  rather,  mottled  with  large  yellow  and 
brown  spots.  The  internal  surface,  or,  rather,  of  the  parts  which  are  in  contact,  is  chest- 
nut brown,  or  bistre  colour  of  different  shades,  so  that  I  am  induced  to  compare  its  ap- 
pearance with  that  of  an  apoplectic  cyst.  It  seems  as  if  in  this,  as  in  the  other  case, 
blood  had  been  effused,  and  then  absorbed. 

The  internal  surface  is  also  rough,  and,  as  it  were,  lacerated ;  a  sort  of  yellowish  or 
chestnut-coloured  pulp  may  be  scraped  off  it.  I  have  seen  roundish,  pulpy  vegetations 
jpringing  from  several  parts  of  this  surface,  sections  of  which  presented  a  yellowish 
colour,  mottled  with  brovra. 

The  name  of  atrabiliary  capsules,  given  to  them  by  Barthohn,  is  undoubtedly  derived 

*  Eustachius,  who  first  described  them,  called  them  glanduUt  qua  renibus  incumbunt. 


446  SPLANCHNOLOGY. 

from  the  deep  brovm  colour  of  their  internal  surface.  That  anatomist  regarded  them  as 
small  pouches  or  capsules,  and  thought  that  they  were  the  reservoirs  of  the  blackish 
fluid  (sanguis  niger,  Bartholin;  succus  atrabiliaris,  atramentum  glandulosum,  Lecat.)  to 
which  the  ancients  gave  the  name  of  atrabilis. 

Structure. — The  supra-renal  capsules  consist  of  two  substances  :  one  external  or  cor- 
tical, yellowish,  and  striated,  which  forms  almost  the  whole  thickness  of  the  capsule  ; 
and  an  internal  or  central  portion,  presenting  the  appearance  of  a  soft  layer  of  a  deep 
chestnut  brown  colour,  and  traversed  by  numerous  vessels.  The  striated  arrangement 
of  the  cortical  layer,  which  is  so  easily  seen  in  large  animals,  is  frequently  effaced  in  the 
human  subject,  where  the  capsule  appears  reduced  to  a  thin  yellowish  lamella,  folded 
back  upon  itself  The  lobular  character  of  the  surface  is  only  apparent,  and  depends 
upon  the  furrows  formed  in  it  for  the  vessels.  The  granular  structure,  admitted  by  most 
of  the  authors  who  have  called  these  organs  glands,  has  not  been  clearly  demonstrated. 

A  fibrous  membrane,  anedogous  to  the  proper  coat  of  the  kidney,  covers  the  supra-renal 
capsules. 

The  capsular  arteries  are  very  numerous  and  very  large,  in  proportion  to  the  size  of  the 
organ  ;  they  are  divided  into  the  superior,  arising  from  the  phrenic,  the  middle,  proceed- 
ing directly  from  the  aorta,  and  the  inferior,  furnished  by  the  renal  arteries.  The  ■veins 
are  very  large,  and  soon  pass  into  the  vena  cava  ;  the  anterior  furrow  is  chiefly  intend- 
ed for  them.  It  h^ls  been  supposed  that  they  open  directly  into  the  cavity  of  the  capsule, 
on  account  of  the  faciUty  with  which  this  latter  may  be  distended  by  injecting  air  or  any 
fluid  into  the  veins.  But  it  is  probable  that  in  such  cases  laceration  has  occurred.  The 
veins  of  the  right  capsule  enter  the  vena  cava  inferior  directly ;  those  of  the  left  enter 
the  renal  vein  of  the  same  side.  The  lymphatic  vessels  are  little  known.  The  veins  are 
very  numerous  ;  they  are  derived  directly  from  the  semilunar  ganglia  and  solar  plexus, 
and  also  from  the  renal  plexus.  It  is  in  vain  to  search  for  the  excretory  duct,  admitted 
by  several  anatomists  ;  and  described  by  some  as  entering  the  pelvis  of  the  kidney,  and 
by  others  as  terminating  in  the  testicle  in  the  male,  and  in  the  ovary  in  the  female. 

Development. — The  supra-renal  capsules  are  relatively  much  larger  in  the  foetus  than 
in  the  adult,  and  they  are  remarkable  in  this  respect,  that  their  size  is  inversely  propor- 
tioned to  that  of  the  kidneys.  They  are  distinct  as  early  as  the  second  month  of  intra- 
uterine life,  and  at  that  time  exceed  the  kidney  both  in  weight  and  size.  This  predom- 
inance continues  during  the  whole  of  the  third  month ;  at  the  fourth,  the  kidneys  and 
the  supra-renal  capsules  are  of  equal  size ;  at  the  sixth  month,  the  capsules  are  not  more 
than  half  as  large  as  the  kidneys  ;  at  birth,  not  more  than  one  third.  Tlie  existence  of 
a  cavity  is  not  more  evident  in  the  foetus  than  in  the  adult. 

In  the  aged,  the  supra-renal  capsules  are  sometimes  very  large,  and  their  colour  is  al- 
ways yellow  at  this  period  of  life. 

Uses. — The  uses  of  the  supra-renal  capsules  are  unknown  ;  we  are  even  ignorant 
whether  they  should  be  classed  lunong  the  glands.  The  great  number  of  vessels  with 
which  they  are  supplied,  and  the  numerous  nerves  distributed  upon  them,  suiEciently 
prove  that  something  more  than  mere  nutritive  changes  must  occur  within  these  organs. 
Their  pathological  anatomy,  which  still  remains  to  be  investigated,  may  perhaps  throw 
some  light  upon  this  obscure  point  of  physiology. 


THE  GENERATIVE  ORGANS. 


The  generative  apparatus  presents  this  remarkable  peculiarity,  that  the  organs  of 
which  it  is  composed  are  divided  between  two  individuals  of  the  same  species ;  and  from 
this  division  results  the  difference  of  sex. 

The  male  sex  is  chiefly  characterized  by  the  faculty  of  producing  a  fecundating  fluid, 
the  spermatic  fluid,  or  semen.  The  female  sex  is  characterized  by  the  faculty  of  produ- 
cing certain  ovules,  which  become  fitted  for  the  reproduction  of  an  individual  of  the  same 
species,  as  soon  as  they  have  been  submitted  to  the  fecundating  influence  of  the  fluid 
secreted  by  the  male.  The  female  sex  is  also  characterized,  in  the  human  species,  and 
in  all  mammalia,  by  the  possession  of  a  gland  (the  mamma),  which  is  intended  to  provide 
nutriment  for  the  newly-born  creature. 

The  genital  organs  occupy  the  lower  extremity  of  the  trunk ;  they  are  situated  in  con- 
tact with  the  termination  of  the  digestive  canal  on  the  one  hand,  and  of  the  urinary  organs 
on  the  other,  with  the  latter  of  which  they  have  the  most  intimate  connexions,  especial- 
ly in  the  male. 

THE  GENERATIVE  ORGANS  OF  THE  MALE. 

The  Testicles  and  their  Coverings. — The  Epididymis,  the   Vasa  Deferentia,  and  VesiculeB 
Seminales. — The  Penis. — The  Urethra. — The  Prostate  and  Cowper^s  Glands. 
The  genital  organs  of  the  male  consist  of  a  secreting  and  an  excretory  apparatus,  com- 
posed of  the  following  parts  :  two  glands,  called  the  testicles ;  two  provisional  excretory 
canals,  the  vasa  deferentia ;  two  reservoirs  for  the  spermatic  fluid  during  the  longer  or 


THE   TESTICLES.  -447 

shorter  intervals  between  the  periods  of  its  expulsion,  named  the  vestcula  seminales ; 
and  certain  ultimate  excretory  canals,  the  ejaculatory  ducts  and  the  urethra.  To  this  lat- 
ter canal  is  annexed  an  erectile  structure,  which  enables  it  to  assume  the  condition  ne- 
cessary for  the  ejection  of  the  fecundating  fluid ;  together,  they  form  the  pe7iis.  The 
prostate  gland  and  Cmcper's  glands  yield  secretions,  the  use  of  which  is  connected  with 
the  generative  functions :  they  may  be  regarded  as  appendages  of  the  urethra. 

The  Testicles  and  their  Coverings. 

The  Coverings  of  the  Testicle. 

The  coverings  of  the  testicle  consist  of  several  layers,  which,  reckoning  from  without 
inward,  are  the  scrotum,  the  dartos,  the  tunica  erythroides,  the  fibrous  coat,  and  the  tu- 
nica vagin£ilis.  There  is  a  sixth  testicular  covering,  named  the  tunica  albuginea ;  but, 
as  it  forms  an  integral  part  of  the  testis,  we  shall  describe  it  with  that  organ. 

The  scrotum,*  or  cutaneous  covering  of  the  testicles,  is  a  sort  of  pouch  or  bag  common  to 
both  of  those  organs ;  the  skin  of  which  it  is  composed  exhibits  the  following  peculiarities : 

It  is  of  a  browner  colour  than  that  of  other  parts  of  the  body,  so  that,  in  some  individ- 
uals, a  layer  of  colouring  matter,  similar  to  that  existing  in  the  negro,  may  be  demonstra- 
ted beneath  it ;  like  the  skin  of  the  penis  and  the  eyelids,  it  is  very  thin,  on  account  of 
the  tenuity  of  its  chorion ;  it  is  much  larger  than  is  needed  for  containing  the  testicle ; 
it  is  provided  with  scattered  and  obliquely  inserted  hairs,  the  follicles  of  which  are  large, 
and  project  upon  the  surface ;  and,  lastly,  its  external  aspect  presents  many  varieties  : 
thus,  it  becomes  flaccid  and  elongated  under  the  influence  of  warmth,  and  in  old  and  en- 
feebled persons,  while,  during  youth,  in  the  robust,  and  under  the  influence  of  cold,  it 
becomes  contracted,  wrinkled,  and  closely  applied  to  the  testicle. 

The  scrotum  is  divided  into  two  equal  halves,  by  a  sort  of  median  line  or  ridge,  caUed 
the  raphe,  from  the  Greek  word  fidnru,  to  sew ;  because  the  two  halves  of  the  skin  ap- 
pear to  be  united  at  this  part,  as  it  were,  by  a  seam. 

The  object  of  the  great  extent  of  the  skin  of  the  scrotum  is,  perhaps,  to  enable  it  to 
cover  the  penis  when  in  a  state  of  erection. 

The  dartos  is  a  reddish  filcunentous  tissue,  traversed  by  a  great  number  of  vessels, 
which  can  be  easily  seen  through  the  skin  of  the  scrotum.  This  tissue  envelops  both 
testicles,  and  furnishes  a  prolongation  interposed  between  them,  and  forming  the  septum 
of  the  dartos.  Upon  the  sides,  and  opposite  the  spermatic  cord,  the  dartos  terminates 
abruptly,  and  is  replaced  by  adipose  cellular  tissue.  In  front  it  is  continued  around  the 
penis ;  behind,  it  is  prolonged  upon  the  median  line,  by  an  angular  extremity,  as  far  as 
the  sphincter  ani. 

It  follows,  therefore,  that  there  is  only  a  single  dartos,  within  which  are  contained 
both  testicles,  a  septum  alone  intervening  between  them.  This  separation  in  the  mid- 
dle line  has  led  some  to  follow  Ruysch,  in  describing  a  distinct  dartos  for  each  testicle. 
The  dartos  is  closely  united  to  the  skin  of  the  scrotum  by  its  external  surface,  and  it  is 
very  loosely  connected  by  extremely  delicate  cellular  tissue,  with  the  subjacent  cover- 
ings, upon  which  it  glides  with  the  greatest  freedom. 

With  regard  to  its  structure,  the  dartos,  at  first  sight,  presents  some  analogy  to  cellu- 
lar tissue,  but  it  differs  from  it  essentially  in  its  aspect ;  for  in  no  situation  does  ceUular 
tissue  exliibit  distinct  reddish  nodulated  filaments,  like  those  of  the  dartos.  It  is  true 
that  these  filaments  are  irregularly  interlaced,  but  the  majority  of  them  peiss  in  a  verti- 
cal direction ;  and  when  a  single  fibre  is  examined,  we  are  struck  with  its  analogy  to 
muscular  tissue. t  It  also  differs  in  its  vital  properties  :  thus,  the  dartos  possesses  the 
property  of  active  contractility,  as  is  seen  in  the  contraction  of  the  scrotum,  and  the  ver- 
micular motions  observed  in  persons  exposed  to  cold,  or  under  the  influence  of  great 
dread,  or  of  the  venereal  orgasm,  and  also  in  the  much  more  evident  contraction  of  the 
scrotum  after  an  irritating  injection  has  been  thrown  into  the  cavity  of  the  tunica  vaginalis. 

It  is,  therefore,  intermediate  between  cellular  and  muscular  tissue,  and  might  be  call- 
ed the  dartoid  tissue.  It  was,  for  a  long  time,  supposed  to  be  confined  to  the  scrotum, 
but  it  is  met  with  in  many  other  parts,  viz.,  the  vagina,  the  substance  of  the  nipple,  and 
the  parietes  of  the  veins,  of  which  it  seems  to  me  to  form  the  external  coat. 

Some  anatomists  regard  the  dartos  as  nothing  more  than  the  remains  of  the  guhcrnac- 
tdum  testis ;  but,  in  the  first  place,  the  dartos  is  found  in  the  foetus,  before  the  descent 
of  the  testicle  ;  and  in  an  adult  whose  testicle  had  not  escaped  from  the  external  ab- 
dominal ring,  I  satisfied  myself  that  the  gubernaculum  and  the  dartos  existed  separately 
and  independently  of  each  other,  t 

*  From  the  Latin  word  scrotum,  a  sac,  or  purse  of  leather.  The  Greek  term  for  the  same  part  is  S/rxM") 
and  hence  the  word  oscheocele,  which  serves  to  designate  every  tumour  developed  in  the  scrotum. 

t  [According  to  M.  Jordan  (Miiller's  Archives,  1834),  the  tissue  of  the  dartos  is  composed  of  uniform  cylin- 
drical filaments,  which  resemble  those  of  cellular  tissue  in  diameter,  but  are  larger  than  the  varicose  fila- 
ments of  voluntary  muscular  fibre,  and  smaller  than  the  involuntary  muscular  fibres,  excepting  those  compo- 
sing the  iris.  They  resemble  cellular  tissue,  and  not  muscle,  in  their  chemical  characters,  and  difT^r  from  the 
fonner  only  in  presenting  a  reddish  aspect,  and  in  being  arranged  into  longitudinal  fasciculi,  instead  of  inter- 
lacing in  all  directions.] 

t  The  specimen  from  which  this  statement  is  taken  has  been  presented  to  the  anatomical  society  hy  M.  Manec 


448  SPLANCHNOLOGY. 

The  dartos  has  also  been  incorrectly  regarded  as  a  continuation  of  the  superficial  Jascta 
(see  Aponeukology). 

The  Tunica  Erythroides. — This  name  (derived  from  the  Greek  word  kpvdph^,  red)  is 
given  to  a  thin  membrane,  formed  by  an  expansion  of  the  fibres  of  the  cremaster.  It  is 
very  well  marked  in  the  young  and  vigorous,  but  becomes  partially  atrophied  in  the  aged.* 

We  have  already  seen  (vide  Obliquus  Internus  Abdominis,  Myology)  that  the  cremas- 
ter is  essentially  formed  of  fibres  arising  directly  from  the  groove  of  the  crural  arch,  on 
the  outer  side  of  the  inguinal  canal.  The  loops  formed  by  the  lower  portions  of  the  ob- 
liquus internus  and  transversalis  are,  where  they  exist,  completely  distinct  from  it.  The 
cremaster  and  the  tunica  erj^hroides,  which  is  an  expansion  of  it,  are  the  agents  of  the 
sudden  upward  movement  of  the  testicle,  which  is  very  distinct  from  the  slow  vermicu- 
lar motion  resulting  from  the  action  of  the  dartos.  In  a  patient  whose  urethra  was  ex- 
tremely irritable,  I  found  that  the  introduction  of  a  bougie  was  followed  by  a  sudden  and 
long-continued  elevation  of  the  testicles,  with  a  separation  of  their  lower  ends.  This 
movement  was  entirely  independent  of  the  dartos  and  scrotum,  which  remained  flaccid 
and  pendent  in  front  of  the  thighs. 

Wlien  the  cremaster  reaches  the  testicles,  it  expands  into  a  number  of  fasciculi,  dis- 
tributed over  the  surface  of  the  fibrous  coat,  and  inserted,  in  the  lower  animals,  by  well- 
marked  tendinous  fibres,  which,  however,  I  have  never  been  able  to  discover  in  man. 
In  hydrocele,  these  fibrous  bundles  resemble  small  cords,  which,  as  Sir  A.  Cooper  ju- 
diciously remarks,  may  be  mistaken  for  veins. 

The  Common  Fibrous  Coat. — This  membrane  is  very  distinct  from  the  tunica  vagina- 
lis, which  lines  its  inner  surface  ;  it  forms  a  common  covering  for  the  testicle  and  the 
spermatic  cord ;  it  is  thin  and  transparent,  narrow  along  the  cord,  and  expanded  below, 
so  as  to  cover  the  testicle.  At  the  inguinal  ring  it  divides  into  two  laminae,  one  of 
which,  almost  always  incomplete,  is  attached  to  the  circumference  of  the  ring,  while  the 
other  seems  to  be  prolonged  within  the  canal,  where  it  is,  however,  very  difficult  to  fol- 
low it.  Modern  anatomists  regard  this  fibrous  tunic  as  a  prolongation  of  the  fascia  trans- 
versalis, which  would  be  dragged  down  with  the  testicle  during  its  descent. 

The  Tunica  Vaginalis,  or  Serous  Coat. — The  tunica  vaginalis  is  a  shut  sac,  and  pre- 
sents two  portions  :  one,  parietal  (p,  fig.  183),  lining  the  fibrous  coat ;  the  other,  reflected 
or  testicular  {v),  which  covers  the  testicle,  without  that  organ  being  contained  within 
the  sac. 

The  intimate  union  of  the  serous  and  fibrous  coats  of  the  testicle  affords  an  example 
of  a  fibro-serous  membrane,  analogous  to  the  dura  mater  and  the  pericardium.  As  the 
reflection  of  the  tunica  vaginalis  upon  the  testicle  takes  place  at  a  variable  height,  it 
follows  that  a  greater  or  less  portion  of  the  cord  is  covered  by  this  coat. 

The  arrangement  of  the  tunica  vaginalis  on  one  side  of  the  epididymis  differs  from 
that  on  the  other.  On  the  outer  side  it  immediately  invests  the  epididymis,  is  then  re- 
flected from  it,  becoming  applied  to  the  part  reflected  from  the  opposite  side  of  the  epi- 
didymis, and  forms  a  cul-de-sac,  by  which  the  middle  of  that  body  is  completely  separa- 
ted from  the  upper  border  of  the  testicle.  At  the  bottom  of  this  cul-de-sac  are  some 
small  openings,  leading  into  a  back  cavity.  It  forms,  therefore,  a  fold  like  the  mesen- 
tery, at  the  middle  of  the  epididymis,  the  two  ends  of  which,  however,  are  closely  ap- 
plied to  the  testicle.  On  the  inner  side  it  rises  higher  upon  the  cord  than  on  the  outer 
side,  and  is  separated  from  the  epididymis  by  the  vas  deferens  and  the  spermatic  ves- 
sels. It  is  easy  to  detach  it  from  the  fibrous  coat,  where  it  is  reflected  upon  the  testi- 
cle, but  it  adheres  closely  to  the  epididymis  and  to  the  tunica  albuginea. 

Its  internal  surface,  free  and  smooth,  exhales  a  serous  fluid,  the  morbid  accumulation 
of  which  constitutes  the  disease  called  hydrocele.  In  most  animals  the  tunica  vaginalis 
communicates  with  the  peritoneum  at  aU  ages  ;  but  in  man  this  communication  exists 
normally  only  during  intra-uterine  life.  After  birth  the  two  cavities  are  perfectly  dis- 
tinct. If,  from  any  cause,  this  separation  is  not  completed,  the  tunica  vaginalis  may 
form  either  a  hernial  sac,  containing  displaced  intestines,  or  a  cyst  containing  serous  fluid 
effused  from  the  abdomen.  In  the  former  case,  the  disease  is  called  congenital  hernia, 
in  the  latter  congenital  hydrocele. 

The  Testicles. 

The  testicles  (testes)  are  two  glandular  organs,  intended  to  secrete  the  spermatic  fluid. 
They  are  situated  in  the  scrotum,  at  the  sides  of  and  below  the  penis,  and  are,  there- 
fore, exposed  to  external  violence.  They  are  supported  by  their  coverings,  and  by  the 
cord  formed  by  the  spermatic  vessels,  and  are  at  a  greater  or  less  distance  from  the  in- 
guinal ring,  according  as  the  dartos  and  cremaster  are  in  a  state  of  relaxation  or  con- 
traction. 

The  testicles  are  not  situated  at  exactly  the  same  height,  the  left  descending  a  little 
lower  than  the  right.     This  arrangement,  which  has  not  escaped  the  observation  of 

*  The  cremaster  is  extremely  well  developed  in  the  stallion  ;  in  which  animal  it  is  easy  to  establish  the 
distinction  between  this  muscle  and  the  lower  fibres  of  the  internal  oblique,  the  loops  of  which  do  not  exist  in 
all  subjects. 


THE   TESTICLES.  449 

painters  and  sculptors,  assists  in  protecting  them  from  injury  by  enabling  them  to  glide 
one  above  the  other  when  the  thighs  are  closely  approximated,  and  thus  to  avoid  com- 
pression. Their  situation  is  not  the  same  at  all  periods  of  life.  In  the  foetus,  they  are 
contained  within  the  abdominal  cavity.  Sometimes  they  remain  permanently,  or  much 
longer  than  usual  in  that  situation,  which,  in  the  natural  state,  is  merely  temporary. 

Number. — The  varieties  in  the  number  of  the  testicles  are  most  of  them  only  appEirent. 
Thus,  for  example,  in  almost  all  monorchides  (persons  having  but  one  testis  :  from  fiovog, 
single,  and  bpxi-u  a  testicle),  that  testicle  which  is  absent  from  the  scrotum  is  situated 
in  the  abdomen.  Nevertheless,  I  have  had  occasion  to  dissect  an  individual  who  had 
only  one  testicle  ;  there  was  an  atrophied  vesicula  seminalis  on  the  side  where  the  tes- 
ticle was  wanting  ;  the  vas  deferens  commenced  at  this  vesicle,  and  was  lost  upon  the 
side  of  the  bladder.  I  was  not  able  to  examine  the  spermatic  vessels.  The  examples 
of  three,  four,  or  five  testicles  are  not  well  attested.*  An  epiploic,  or  fatty  tumour,  or 
a  cyst,  may  have  been  mistaken  for  a  testicle. 

Size. — The  testicles  vary  in  size  in  different  individuals,  and  still  more  at  different 
ages.  At  the  period  of  puberty,  the  testicle,  which  up  to  that  time  had  been,  as  it  were, 
in  a  state  of  atrophy  in  comparison  with  the  rest  of  the  body,  increases  greatly  in  size. 
This  atrophy,  which  is  normal  before  puberty,  may  continue  to  a  more  advanced  age. 
In  a  subject  about  twenty  years  of  age,  in  which  the  penis  and  larynx  were  highly  de- 
veloped, I  found  the  two  testicles  atrophied :  they  weighed  less  than  a  drachm ;  the 
epididymis,  although  it  was  atrophied,  was  larger  than  the  body  of  the  testicle. 

The  two  testicles  are  not  exactly  of  the  same  size :  the  left  is  generally  larger  than 
the  right ;  but  this  difference  is  so  slight  and  inconstant,  that  some  anatomists  have 
even  thought  that  a  shght  predominance  may  be  observed  in  the  right. 

The  following  are  the  average  dimensions  of  the  testicle :  Length,  two  inches  ;  breadth, 
one  inch  ;  thickness,  eight  lines. 

Weight. — According  to  Meckel,  the  weight  of  the  testicle  is  four  drachms ;  according 
to  Sir  Astley  Cooper,  one  ounce. 

Consistence. — It  is  extremely  important,  especially  in  a  practical  point  of  view,  to 
judge  of  the  natural  consistence  of  the  testicle.  The  character  of  this  consistence  is 
determined  less  by  the  proper  substance  of  the  testicle  than  by  the  degree  of  tension  of 
its  immediate  covering ;  and  in  this  respect  the  consistence  of  the  testicle  very  much 
resembles  that  of  the  eye.  In  the  aged,  the  seminiferous  ducts  being  empty,  the  testi- 
cle becomes  soft,  and,  as  it  were,  atrophied.  It  would  be  still  less  consistent,  if  it  were 
not  for  the  serous  fluid  with  which  the  cellular  tissue  between  these  ducts  becomes  in- 
filtrated. 

Figure,  Direction,  and  Relations. — The  testicle  is  oval,  but  flattened  at  the  sides.  This 
form,  added  to  the  polished  and  slippery  character  of  its  surface,  enables  it  easily  to 
avoid  compression.  The  long  diameter  or  axis  of  the  testicle  is  directed  obliquely  down- 
ward and  backward ;  its  lateral  surfaces  and  its  lower  borderf  are  convex,  free,  smooth, 
and  constantly  lubricated  by  the  serosity  of  the  tunica  vaginalis.  The  upper  Border  is 
straight ;  it  is  directed  backward,  is  embraced  by  the  epididymis,  which  surmounts  it 
like  the  crest  of  a  helmet,  and  is  covered  by  the  tunica  vaginalis  in  a  small  portion  only 
of  its  extent.  The  spermatic  vessels  enter  at  the  inner  part  of  this  border,  and  behind 
the  head  of  the  epididymis.  The  anterior  extremity  of  the  oval  is  the  larger,  and  is  di- 
rected upward  and  forward ;  the  posterior  extremity  is  turned  backward  and  downward. 
The  white  colour  of  the  surface  of  the  testicle  is  owing  to  its  proper  fibrous  covering, 
which,  on  account  of  its  whiteness,  is  called  the  tunica  albuginea. 

Structure. — The  constituent  parts  of  the  testicle  are  a  fibrous  membrane,  a  proper  tis- 
sue, and  certain  vessels  and  nerves. 

The  fibrous  membrane,  tunica  propria  sive  albuginea,  is  white,  strong,  and  inextensible  ; 
it  is  analogous  to  the  sclerotic  coat  of  the  eye,  and,  like  it,  forms  the  most  external  coat 
or  shell  of  the  organ  which  it  covers. 

The  tunica  vaginalis  invests  the  outer  surface  of  the  tunica  albuginea,  excepting  op- 
posite the  epididymis,  where  the  fibrous  coat  is  destitute  of  the  serous  membrane  for  a 
considerable  extent.    The  serous  and  fibrous  layers  adhere  closely  to  each  other. 

Within  the  substance  of  the  tunica  albuginea,  but  nearer  the  internal  than  the  exter- 
nal surface,  are  a  great  number  of  tortuous  vessels,  which  may  be  seen  through  the 
semi-transparent  fibrous  layer  by  which  they  are  covered.  These  vessels  project  on  the 
internal  surface  of  the  tunica  albuginea,  so  that  at  first  it  might  be  thought  that  they 
vvere  simply  in  contact  with  the  membrane,  and  not  within  its  substance. t 

*  1  have  been  consulted  concerning  a  child,  who  appeared  to  me  to  have  two  testicles  upon  one  side,  each 
of  which  was  as  large  as  that  of  the  opposite  side  ;  but  it  is  impossible  to  decide  with  certainty  upon  such  a 
matter  until  dissection  has  shown  the  true  nature  of  pretended  supernumerary  testicles.  Nevertheless,  tli« 
kind  of  pain  felt  upon  pressing  the  body  imagined  to  be  a  testicle  may  afford  tolerably  satisfactory  indications 
during  life. 

t  [M.  Cruveilhier  differs  from  mos^  other  anatomists  in  applying  the  terms  upper  and  lower  to  the  opposite 
borders  of  the  testicle,  instead  of  posterior  and  anterior  ;  on  the  contrary,  he  describes  the  two  extremities  of 
this  organ  as  anterior  and  posterior,  instead  of  upper  and  lower,  as  is  usually  the  case.] 

i  The  existence  of  numerous  vessels  within  tlie  substance  of  the  tunica  albuginea  has  led  Sir  Astley  Coojh 

Ti  L  L 


450 


SPLANCHNOLOGY 


The  internal  surface  of  the  tunica  albuginea  is  in  immediate  relation  with  the  proper 
Fig.  183.  substance  of  the  testicle,  and  is  connected  with  it  by  a  great  num- 

/  .  ber  of  vascular  filaments,  which  traverse  it  in  all  directions,  and 

divide  it  into  small  masses  or  lobules,  and  also  by  the  extension  of 
the  substance  of  the  gland  itself  into  oblique  culs-de-sac,  or  cells 
formed  by  the  tunica  albuginea,  several  of  which  are  a  line  and  a 
half  or  two  lines  deep.  When  the  tunica  albuginea  is  carefully  re- 
moved, filaments  of  the  glandular  substance  are  seen  escaping  from 
these  small  cells,  which  are  most  numerous  at  the  upper  borders 
of  the  testicle.  The  strength  of  the  vascular  filaments  which  trav- 
erse the  testicle  has  led  to  the  opinion  that  they  are  all  enveloped 
by  a  fibrous  sheath  derived  from  the  tunica  albuginea,  but  I  have 
never  been  satisfied  of  the  existence  of  these  sheaths.* 

At  the  upper  border  of  the  testicle,  the  tunica  albuginea  becomes 
remarkably  thickened,  and  forms  the  corpus  Highmori,  or  medias- 
tinum testis  ( Cooper).  In  order  to  obtain  a  correct  notion  of  this 
structure,  it  is  necessary  to  make  a  vertical  section  of  the  testicle 
at  right  angles  with  its  long  diameter  :  we  then  observe  a  nucleus  (i,  fig.  183),  or  fibrous 
thickening  of  a  triangular  shape,  perforated  by  bloodvessels,  but  do  not  at  first  sight  dis- 
cover any  canals  in  it ;  so  that  we  might  be  inclined  to  agree  with  Winslow  (who  called 
it  the  nucleus  of  the  testis)  in  denying  that  it  contains  any  canals ;  or,  rather,  with  Swam- 
merdam,  in  regarding  those  canals  that  do  exist  in  it  as  destined  exclusively  for  the  ar- 
teries and  veins. 

If,  after  dividing  the  testicle  along  its  convex  border,  we  reflect  the  tunica  albuginea, 
we  shall  see  that  near  the  upper  border  the  filaments  (a  a,  fig.  184)  which  constitute  the 
substance  of  the  testicle  enter  {b  b)  numerous  spaces  existing  in  the  tunica  albuginea  at 
this  part,  pass  towards  the  thickening  (»')  of  the  upper  border,  traverse  it  (c)  from  its  pos- 
terior to  its  anterior  extremity,  and  then,  uniting  together  into  a  greater  or  less  number 
of  tubes,  perforate  (d)  the  tunica  albuginea  opposite  the  head  of  the  epididymis  (e). 

The  corpus  Highmorianum,  moreover,  exists  only  in  the  anterior  half  of  the  upper 
border  of  the  testicle  (see  i,  fig.  184).  All  the  bloodvessels  reach  the  testicle  at  this 
point,  and,  having  entered  it  there,  divide  into  two  sets ;  one  of  these  is  situated  in  the 
substance  of  the  fibrous  coat,  so  as  to  form  its  sinuses  (the  tunica  vasculosa),  and  fur- 
nishes a  multitude  of  vessels,  which  are  given  off  from  it  in  succession,  and  are  distrib- 
uted to  the  substance  of  the  gland.t  Among  these  vessels,  I  would  particularly  notice 
one  tortuous  artery  which  passes  from  before  backward  along  the  upper  border  of  the 
testicle.  The  other  set  of  vessels  perforate  the  corpus  Highmorianum  directly,  and  pass 
from  the  upper  to  the  lower  border  of  the  testicle.  The  corpus  Highmorianum,  then,  is 
a  thickening  of  the  tunica  albuginea,  which  occupies  the  anterior  half  of  the  upper  bor- 
der of  the  testicle,  and  is  perforated  by  the  filaments  composing  the  proper  tissue  of  the 
testicle,  and  also  by  a  great  number  of  bloodvessels. 
Proper  Tissue. — The  proper  substance  of  the  testicle  resembles  a  soft  yellowish  pulp, 
grooved  by  a  multitude  of  small  tense  and  strong  columns, 
which  divide  it  into  a  great  number  of  masses  or  lobules  (a  a, 
fig.  184).  These  small  columns  are  nothing  more  than  the 
vessels  given  off  from  the  tunica  albuginea.t  Each  lobule  rep- 
resents a  pyramid,  the  apex  of  which  is  directed  towards  the 
upper  border  of  the  gland,  and  the  base  towards  its  lower  bor- 
der. The  lobules  consist  of  a  collection  of  extremely  delicate 
filaments,  folded  a  very  gi-eat  number  of  times  upon  themselves, 
so  as  to  resemble  the  granules  of  glands,  and  have,  in  fact,  been 
described  as  such  by  some  anatomists.^  These  filaments  are 
the  seminiferous  tubes,  which  were  injected  by  Haller  and  Mon 


Fig.  184. 


er  to  describe  two  layers  in  it ;  an  external,  which  he  compared  to  the  dura 
mater,  and  an  internal  (the  tunica  vasculosa),  which  he  likened  to  the  pia 
mater,  I  cannot  admit  this  analog-y.  The  vessels  contained  in  the  tunica  al- 
buginea rather  resemble  the  sinuses  of  the  dura  mater  than  the  vascular  net 
work  of  the  pia  mater.  *  See  note,  p.  421 

t  [According  to  Sir  Astley  Cooper,  many  of  the  arterial  vessels  pass  along 
the  septa,  extending  from  the  inner  surface  of  the  tunica  albuginea  to  the 
mediastinum,  and  then  turn  back  and  are  distributed  upon  the  lobes.  The 
principal  veins  arise  upon  the  larger  ends  of  the  lobes,  pass  up  to  the  mediasti- 
num, and  perforate  it.] 

t  [Sir  Astley  Cooper  has  described  fibrous  columns  which  extend  from  the 
inner  surface  of  the  tunica  albuginea,  and  unite  with  similar  prolongations  given  off  from  the  mediastinum 
testis,  and  forming  the  sides  of  the  cells  described  by  M.  Cruveilhier  (p.  449).  From  these  columns  lateral 
membranes  proceed,  so  as  to  form  septa  between  the  larger  masses  of  glandular  structure,  while  other  finer 
membranous  extensions  enclose  the  small  lobes  in  separate  pouches.  The  larger  bloodvessels  are  supported 
by  the  columns,  and  the  smaller  ones  ramify  upon  the  membranous  septa  and  pouches.] 

4  Riolanus  described  a  fibrous  thickening'of  the  proper  coat  of  the  testicle.     The  description  given  by  High- 
more  is  very  confused  ;  he  describes  a  body  obscure  aut  omnid  non  cavum,  which  appears  to  perforate  the  tu- 
nica albuginea,  and  to  convey  the  semen  to  the  epididymis  ;  he  has  also  represented  as  opening  into  this  canal 
•  certain  parallel  vessels,  which  he  considered  to  be  an  artery  and  a  vein. 


THE    TESTECLES.  461 

ro  from  the  vas  deferens.  I  have  in  vain  attempted  to  perform  the  same  experiment ; 
the  mercury  never  passed  beyond  the  epididymis.  It  has  been  said  that  each  lobule  is 
formed  by  one  or  two  tubuh,  and  the  number  of  these  tubes  has  been  calculated  at  300. 
Each  tubulus  is  said  to  be  16  feet  long,  and  -^^o  of  an  inch  in  diameter.  According  to 
Monro's  calculation,  there  would  be  5000  feet  of  tubuli  seminiferi  in  the  small  space  oc- 
cupied by  one  testicle. 

If  we  take  hold  of  the  substance  of  the  testicle  with  a  pair  of  pincers,  and  then  draw 
it  out  slowly,  we  shall  raise  a  number  of  apparently  knotted  filaments  from  the  common 
mass,  some  of  which  will  break  immediately,  while  others  may  be  drawn  out  to  a  foot, 
a  foot  and  a  half,  or  two  feet,  without  breaking.  It  is  particularly  easy  to  pull  out  the 
filaments  when  the  tissue  of  the  testicle  is  very  moist.  The  little  knots  disappear  du- 
ring this  process,  and  the  tubuli  then  assume  the  character  of  straight  and  almost  trans- 
parent filaments.* 

The  proper  tissue  of  the  testicle  adheres  to  the  tunica  albuginea  by  the  bloodvessels 
only,  excepting  near  the  upper  border  of  the  testicle.  In  this  situation  the  tubuli  are 
lodged  in  the  cells  or  spaces,  already  described,  in  the  substance  of  the  tunica  albuginea  ; 
they  all  pass  towards  the  corpus  Highmori,  traverse  it  from  behind  forward,  and  form 
within  its  substance  what  Haller  described  as  the  rete  vasculosum  testis  {,c,figs.  184, 185), 
because  he  supposed  that  the  seminiferous  tubes  in  this  situation  communicated  with 
each  other.  + 

Lastly,  the  tubes  composing  the  rete  unite  into  an  indeterminate  niunber  of  efferent 
ducts  {d),  estimated  at  from  ten  to  thirty,  which  perforate  the  tunica  albuginea,  opposite 
the  head  of  the  epididymis. 

Vessels  and  Nerves. — ^The  testicular  artery,  the  principal  division  of  the  spermatic,  di- 
vides, before  entering  the  testis,  into  several  branches,  which  pass  into  the  tunica  albu- 
ginea along  the  upper  border  of  the  gland,  and  are  distributed  as  I  have  already  pointed 
out  when  speaking  of  the  corpus  Highmori.  The  veins  are  very  numerous,  are  arranged 
in  an  analogous  manner,  and  form  the  spermatic  veins.  The  lymphatics  are  very  numer- 
ous, and  are  divided  into  the  superficial  and  deep. 

The  nerves  are  derived  both  from  the  ganglionic  and  the  cerebro-spinal  system.  They 
have  not  been  traced  mto  the  interior  of  the  testicle,  and  yet  the  sensibility  of  that  organ 
is  sufficient  evidence  of  their  existence  there. 

The  serous  cellular  tissue,  by  which  the  seminiferous  ducts  are  united,  is  so  delicate, 
that  it  can  only  be  shown  bv  the  aid  of  a  very  favourable  light 

The  Epididymis. 

The  epididymis  (e  /,  Jigs.  184,  185)  is  the  vermiform  appendage  which  lies  along  the 
superior  border  of  the  testicle,  like  the  crest  upon  a  helmet.  Its  name  is  derived  from 
its  position  (enl,  upon,  6i6vfiog,  the  testicle). 

It  is  so  situated  that  it  does  not  precisely  occupy  the  superior  border  of  the  testicle, 
but  encroaches  a  little  upon  its  outer  face  (see  Jig.  182,  a  section  of  the  right  testis),  so 
that  when  the  tunica  vaginalis  is  opened,  and  the  inner  side  of  the  testicle  examined, 
we  cannot  see  the  epididymis.  It  is  closely  connected  with  the  testicle  by  its  anterior 
extremity,  which  is  remarkably  enlarged,  and  is  called  the  head,  or  globus  majm-  (e) ;  its 
middle  portion  or  body  (/)  is  separated  from  the  testis ;  and  it  again  adheres  by  its  pos- 
terior extremity,  called  the  tail,  or  globus  minor  (g) ;  which,  after  being  prolonged  as  far 
as  the  posterior  extremity  of  the  testis,  turns  upward,  by  being  reflected  upon  itself,  £md 
gives  origin  to  the  vas  deferens  (<)•  It  is  flattened  from  above  downward,  concave  be- 
low, and  slightly  flexuous  ;  its  two  extremities  are  covered  by  the  tunica  vaginalis  only 
above  and  on  the  outside,  but  its  body  is  completely  enclosed  by  that  membrane,  which 
forms  a  fold  for  it  hke  the  mesentery.    (See  Tunica  Vaginalis.) 

Structure. — When  the  tunica  vaginalis,  which  gives  the  epididymis  a  smooth  appear- 
ance, is  removed  (as  in^.  185),  the  latter  resembles  a  cord,  so  twisted  upon  itself  that 
it  would  appear  impossible  at  first  sight  to  disentangle  it.  This  cord  is  hollow,  as  may 
be  shown  by  injecting  mercury  or  a  coloured  liquid  into  it  through  the  vas  deferens. 
The  canal  or  duct  which  forms  the  epididymis  is  not  unfrequently  found  distended  with 
semen ;  and  then  we  may  ascertain  by  simple  inspection,  as  weU  as  by  injecting  it,  that 
it  is  of  a  determinate  size,  and  that  its  parietes  are  thin  and  semi-transparent. 

The  epididymis  is  intimately  connected  with  the  body  of  the  testicle  by  its  head  only ; 
the  other  means  of  attachment  between  the  two  parts  consisting  exclusively  of  rather 
dense  cellular  tissue,  and  a  fold  of  the  tunica  vaginahs.  The  head  of  the  epididymis  is 
united  to  the  testicle  by  several  ducts,  the  number  of  which  varies  from  ten  to  thirty. 

*  [The  seminiferous  tubes  are  of  the  same  diameter  throughout.  According  to  Lauth,  they  most  commonly 
terminate  in  loops,  and  by  numerous  anastomoses  ;  in  one  instance  oniy  did  he  observe  a  free  closed  extrem- 
ity. In  some  animals,  Miillcr  found  the  seminal  tubes  ending  in  free  extremities  ;  and  the  same  mode  of  ter- 
mination was  frequently  seen  by  Krause  in  the  human  testis.  Like  the  uriniferous  tubes,  the  tubuli  seminif- 
eri terminate,  therefore,  in  two  ways.] 

t  [Immediately  before  the  tubuli  pass  into  the  corpus  Highmori  to  form  the  rete,  they  become  rather  larger 
xad  straight,  and  are  hence  called  the  tubuli  recti  (d  d,fig.  184) :  the  tubuli  composing  the  rete  are  stated  by 
Lauth  to  vary  from  seven  to  thirteen  ;  ihey  are  tortuous,  and,  as  supposed  by  Haller,  anaston-ose.] 


452  SPLANCHNOLOGY. 

rhey  form  several  groups,  which  emerge  from  the  corpus  Highmori,  and  immediately 
Fig.  185.  afterward  become  convoluted,  so  as  to  form  the  head  or  glohun  major 

of  the  epididymis.  These  vessels,  which  are  called  the  vasa  efferentia, 
or  coni  vasculosi  (d),  are  perfectly  distinct  at  their  exit  from  the 
corpus  Highmori ;  but,  after  a  short  course  in  the  globus  major,  they 
unite  into  a  single  canal,  the  numerous  convolutions  of  which  consti 
tute  the  vermiform  body  called  the  epididymis.  It  is  possible,  by 
careful  and  minute  dissection,  to  unravel  this  duct,  the  folds  of 
which,  shaped  like  the  figure  8,  are  united  by  very  dense  cellular  tis- 
sue. Monro,  who  even  counted  the  number  of  its  inflections,  has 
calculated  its  length  to  be  about  thirty-two  feet.* 

It  is  supplied  with  arteries,  and  some  veins  and  numerous  lymphatics 
issue  from  it.  Its  nerves  are  derived  from  the  testicular,  and  accom- 
pany a  small  branch  of  the  hypogastric  artery,  which  has  been  named 
the  deferential  artery  by  Sir  Astley  Cooper. 

Not  unfrequently  a  dense  cord,  having  the  same  structure  as  the 
vas  deferens,  is  found  proceeding  from  the  epididymis ;  this  cord  is 
the  vas  aberrans. — {Holler.) 

The  supernumerary  ducts  of  this  nature,  injected  with  mercury  by 
Haller,  extended  for  a  few  inches  into  the  cellular  tissue  of  the  sper- 
matic cord. 

The  Vas  Deferens. 

The  vas  deferens  {t,  figs.  181,  184,  186),  the  excretory  duct  of  the  testicle,  extends 
from  the  epididymis  to  the  ejaculatory  duct  {fig.  186),  which  may  be  regarded  as  a  con- 
tinuation of  it.  It  conunences  at  the  point  where  the  caudal  extremity  of  the  epididymis 
becomes  separated  from  the  testicle. 

The  following  is  a  description  of  its  very  complicated  course  :  in  its  first  or  testicular 
portion  it  passes  from  behind  forward  and  upward  along  the  upper  border  of  the  testicle, 
almost  parallel  with  the  epididymis,  from  the  inner  edge  of  which  it  is  separated  only 
by  the  spermatic  arteries  and  veins.  In  this  first  portion  of  its  course  the  vas  deferens 
pretty  closely  resembles  a  braided  cord,  and  is,  moreover,  folded  a  great  number  of 
times,  like  the  canal  of  the  epididymis. 

The  seconA,  funicular  or  ascending  portion  of  the  vas  deferens,  forms  part  of  the  sper- 
matic cord,  and  passes  directly  upward  towards  the  inguinal  ring.  There  it  is  in  rela- 
tion with  the  spermatic  artery  and  veins,  which  are  placed  in  front  of  it,  and  from  which 
it  is  perfectly  distinct,  being  surrounded  by  an  independent  sheath  of  filamentous  cellular 
tissue.  It  is  convoluted,  at  its  lower  part,  for  the  space  of  an  inch  or  an  inch  and  a  half, 
but  is  straight  in  the  rest  of  its  extent.  The  third  or  inguinal  portion  of  the  vas  defer- 
ens passes  through  the  inguinal  canal  to  enter  into  tlie  abdomen.  Like  that  canal,  it  is 
directed  obliquely  upward,  outward,  and  backward,  and  is  from  an  inch  and  a  half  to  two 
inches  and  a  half  in  length.  The  lower  margins  of  the  obliquus  internus  and  transver- 
salis  seem  to  curve  over  it ;  it  crosses  the  epigastric  artery  at  right  angles,  a  little  above 
the  bend  formed  by  that  artery,  where  it  changes  its  direction  from  horizontal  to  verti- 
cal; in  this  portion  of  its  course,  as- well  as  in  the  preceding,  the  vas  deferens  forms 
part  of  the  spermatic  cord.  The  fourth  or  vesical  portion. — Having  arrived  within  the 
abdomen,  the  vas  deferens  leaves  the  vessels  and  nerves,  proceeds  vertically  dovraward 
into  the  pelvis,  passes  along  the  side  {fig.  181)  and  then  the  posterior  surface  {fig.  186) 
of  the  bladder,  in  which  position  it  is  retained  by  the  peritoneum,  crosses  very  obliquely 
the  fibrous  cord  formed  by  the  remains  of  the  umbilical  artery,  and  is  then  directed  in- 
ward and  downward  to  the  inferior  fundus  of  the  bladder.  Having  arrived  opposite  and 
internally  to  the  entrance  of  the  ureter  into  the  bladder,  it  is  directed  horizontally  in- 
ward and  a  little  forward  like  the  vesicula  seminalis  {s,  figs.  181,  186),  internally  to 
which  it  is  situated,  and  gradually  approaches  nearer  and  nearer  to  its  fellow  of  the  op- 
posite side,  with  which  it  seems  to  be  joined.  At  the  anterior  extremity  of  the  vesicula 
seminalis  it  unites  at  an  acute  angle  with  the  efferent  duct  {c,fig.  186)  of  the  latter,  the 
union  of  the  two  forming  the  ejaculatory  duct  {d).  In  its  vesical  portion,  for  about  two 
inches  above  the  vesiculae  seminales,  the  vas  deferens  is  considerably  dilated,  and,  at 
the  same  time,  its  parietes  become  thinner. 

On  the  inner  side  of  the  vesicula  seminalis  the  canal  still  continues  dilated,  and  is 
sometimes  sacculated,  and  has  a  flexuous  appearance.  Each  sacculus  is  formed  by  a 
small  ampulla,  which  opens  into  the  cavity  of  the  canal. 

The  vas  deferens  forms,  therefore,  in  this  situation,  a  sort  of  provisional  reservoir,  re- 
sembling, in  its  internal  aspect  and  structure,  the  vesiculae  seminales. 

The  spermatic  cord,  or  cord  of  the  spermatic  vessels,  is  formed  by  the  spennatic  arteryt 

*  [The  average  length  of  the  vasa  efferentia  is  stated  by  Lauth  to  be  eight  inches  ;  they  diminish  in  size 
as  they  approach  the  canal  forming  the  epididymis,  which  they  enter  at  intervals  of  about  three  and  a  quajter 
nches  from  each  other.    The  length  of  that  canal  is,  according  to  the  same  author,  about  twenty-one  feet.] 
t  [Also  the  deferential  artery,  and  the  cremasteric  branch  of  the  epigastric  artery.] 


THE    TESTICLES.  453 

and  veins,  the  lymphatic  vessels,  the  spermatic  plexus  of  nerves,  a  branch  of  the  genito- 
crural  nerve,  and  the  vas  deferens,  all  being  surrounded  by  the  cremaster  muscle  and 
the  common  fibrous  coat. 

Structure. — The  following  are  the  principal  points  concerning  the  structure  of  the  vas 
deferens  :  It  is  harder  than  any  other  excretory  duct,  and  it  can  be  recognised  by  the 
touch  among  the  other  constituent  parts  of  the  cord,  both  in  the  healthy  and  in  the  dis- 
eased state,  in  which  latter  condition  it  may  become  considerably  enlarged  It  is  per- 
fectly cylindrical.  Its  bore  is  so  small  that  it  is  almost  capillary,  and  will  scarcely  admit 
Mejan's  probe.     Its  parietes  are  thick,  and  contrast  singularly  with  the  fineness  of  its  bore. 

Several  anatomists  admit  the  existence  of  circular  and  longitudinal  muscular  fibres  in 
this  duct.  Leuwenhoek  demonstrated  longitudinal  fibres,  with  circular  fibres  beneath 
them.  All  that  I  have  been  able  to  discover  in  the  human  vas  deferens,  even  by  the  aid 
of  the  glass,  are  circular.  In  their  appearance,  and  kind  of  cohesion,  they  present  much 
analogy  to  muscular  fibres  ;  but  it  is  in  the  larger  animals  only,  in  the  horse,  for  exam- 
ple, that  their  muscularity  can  be  clearly  ascertained,  and  that  we  find  distinctly  a  very 
thin  longitudinal  and  superficial  layer  of  fibres,  with  very  thick  and  strong  circular  fibres 
beneath.  The  internal  surface  of  the  vas  deferens  is  white,  rough,  and  alveolar ;  its 
roughness  is  due  to  small  and  very  white  fibrous  fasciculi,  some  of  which  are  directed 
longitudinally,  while  others  are  circular,  and  which  are  either  regularly  or  irregularly  ar- 
ranged. 

The  mucous  membrane  lining  the  vas  deferens  is  so  thin  that  it  is  difficult  to  demoQ- 
strate  it. 

The  Vesicula  Seminales. 

The  vesiculae  seminales  are  two  membranous  pouches,  which  serve  as  reservoirs  for 
the  semen.* 

They  are  sitimted  {s,fig.  181)  between  the  rectum  and  the  bladder,  on  the  outer  side 
of,  and  parallel  to,  the  vasa  deferentia.     As  they  are  di-  p.    jgg 

rected  obliquely  inward  and  forward  (s,  fig.  186),  their  an- 
terior extremities  are  closely  approximated,  being  separa- 
ted from  each  other  merely  by  the  width  of  the  vasa  defer- 
entia, while  their  posterior  extremities  are  very  far  asun- 
der ;  they  thus  form  two  sides  of  an  isosceles  triangle, 
within  the  area  of  which  the  bladder  (a)  is  in  immediate 
relation  with  the  rectum.  They  are  flattened  and  oblong, 
and  are  expanded  at  their  posterior  extremities,  which 
sometimes  project  beyond  the  inferior  fundus  of  the  dis- 
tended bladder,  and  always  do  so  when  that  organ  is  con- 
tracted. Their  anterior  extremities  are  narrowed,  and 
surrounded  by  the  prostate,  and  their  surface  has  a  saccu- 
lated appearance.  They  vary  in  size,  which  is  not  always 
equal  on  the  two  sides  ;  and  they  are  much  larger  in  the 
adult  than  in  youth  or  old  age.  Their  size  also  varies  ac- 
cording to  whether  they  are  empty  or  full.  They  are  from  two  inches  to  two  inches 
and  a  half  long,  and  abou^  six  lines  broad,  and  two  or  three  lines  thick. 

Their  relations  with  the  bladder  and  the  rectum  are  not  direct ;  for  they  are  surround- 
ed with  a  filamentous  tissue,  consisting  of  transverse  fibres,  which  separates  them  from 
the  neighbouring  parts,  and  appears  to  me  to  be  analogous  to  the  tissue  of  the  dartos. 

When  divided  in  various  directions,  the  vesiculae  seminales  exhibit  a  collection  of 
cells,  communicating  with  each  other,  and  filled  with  a  yellowish  brown,  thick,  viscid 
fluid,  very  different  in  appearance  from  semen  as  ejaculated  during  life.  The  sacculi  of 
the  external  surface,  and  the  cells  and  septa  of  the  interior  of  the  vesiculae,  are  formed 
by  the  extremely  complicated  convolution  of  a  sort  of  intestinal  tube,  or  narrow  oblong 
sac,  on  which  I  have  never  been  able  to  find  any  appendages,  ramifications,  or  divertic- 
ula. When  unravelled  (as  at  s),  its  length  varies  from  six  to  eight  inches  ;  its  convo- 
lutions are  attached  to  each  other  by  fibrous  tissue,  but  they  may  always  be  separated, 
either  with  or  without  maceration.  I  have  seen  an  unfolded  vesicle  a  foot  in  length  ;  in 
other  subjects  I  have  seen  two  distinct  pouches  on  each  side,  one  of  which  was  extreme- 
ly small.  Lastly,  the  internal  surface  of  the  seminal  vesicles  has  the  same  rough  and 
alveolar  appearance  as  that  of  the  vasa  deferentia. 

*  [The  semen,  considered  anatomically,  consists,  according  to  Wagner,  of  liquor  seminis,  seminal  granules, 
and  seminal  animalcules  ;  the  latter  were  discovered  by  Ham,  and  described  by  Leuwenhoek.  In  the  human 
subject,  the  seminal  granules  are  round  granulated  bodies,  about  ^-^Vo'^  '"  TbVu'^  °^  ^"^  '"'^^  '"^  diameter ; 
the  seminal  animalcules,  or  spermatozoa,  have  an  elliptical  body,  about  ^.^^^th  to  >  A  ^  th  of  an  inch  in  di- 
ameter, and  a  long  caudal  filament :  their  total  length  is  from  ^J^th  to  j-^-^th  of  an  inch  :  their  organization 
is  yet  unknown  ;  but  in  the  spermatozoa  of  the  bear,  Valentin  has  lately  observed  evidences  of  a  definite  in- 
ternal structure  ;  they  perform  very  rapid  movements,  which  continue  some  hours  after  evacuation  or  removal 
from  the  body.  They  are  not  found  before  puberty,  and  then  only  in  the  vesicuIiE  seminales,  vas  deferens, 
and  epididymis.  The  semen  of  the  testis  contains,  besides  the  seminal  granules,  certain  vesicles  or  cysts,  in 
which,  as  shown  by  Wagner,  the  future  spermatozoa  are  developed. i 


454  SPLANCHNOLOGY. 


The  structure  of  the  parietes  of  the  vesicles  is  also  precisely  the  same  as  that  of  the 
deferent  vessels,  excepting  that  the  external  coat  is  thinner ;  in  the  larger  animals  this 
coat  is  evidently  muscular,  and  it  appears  to  me  to  be  so  in  the  human  subject  also.  I 
have  in  vain  attempted  to  find  the  glands  described  by  Winslovsr  in  the  substance  of  the 
walls  of  the  seminal  vesicles. 

Efferent  Ducts  of  the  Vesiculcs  Seminales. — From  the  anterior  extremity  or  neck  of  each 
vesicle,  which  we  have  said  is  situated  in  the  substance  of  the  prostate,  arises  a  very 
delicate  duct,  the  efferent  duct  (c)  of  the  vesicula  seminalis :  this  duct  almost  immediately 
unites  with  the  vas  deferens,  the  walls  of  which  are  thin  and  very  dilatable  in  this  situa- 
tion. By  the  junction  of  the  two,  which  occurs  at  a  very  acute  angle,  the  ejaculatory  duct 
(d)  is  formed ;  this  passes  through  the  prostate  (which  is  shown  divided  in  the  figure), 
upward  and  forward,  parallel  to  and  in  contact  with  its  fellow  of  the  opposite  side,  but 
without  communicating  with  it.  The  ejaculatory  ducts  have  very  thin  parietes,  but  they 
are  tolerably  wide,  and  very  dilatable ;  closely  apphed  to  each  other,  they  open  separately 
on  the  enlarged  extremity  of  the  verumontanum,  one  on  the  right,  the  other  on  the  left 
(Jg.  182). 

The  Penis. 

The  penis,  the  organ  of  copulation,  is  situated  in  front  of  the  symphysis  pubis.  When 
collapsed,  it  is  flaccid,  and  forms  a  curve  with  the  concavity  looking  downward  ;  but  du- 
ring erection,  it  is  large  and  hard,  and  forms  a  curve  with  its  concavity  turned  upward. 

It  is  cylindrical  when  collapsed,  but  has  a  triangular  prismatic  form,  with  blunt  edges, 
when  in  the  opposite  condition.  Two  of  these  edges  are  lateral,  and  are  formed  by  the 
projection  of  the  corpus  cavemosum  ;  the  other  is  anterior,  and  corresponds  with  the 
canal  of  the  urethra.  Its  posterior  extremity  is  attached  to  the  pubis  ;  its  anterior  ex- 
tremity forms  a  conical  enlargement,  called  the  glans,  on  which  is  seen  the  orifice  of  the 
urethra. 

Structure. — The  penis  consists  essentially  of  the  corpus  cavemosum  and  the  canal  of 
the  urethra,  the  expanded  extremity  of  which  forms  the  glans  penis.  Some  proper  mus- 
cles are  attached  to  it ;  it  receives  large  vessels  and  nerves,  and  it  is  covered  by  integu- 
ment. 

The  Skin  of  the  Penis  and  Prepuce. — The  skin  of  the  penis  has  several  peculiarities  : 
thus,  it  is  very  thin,  although  not  so  thin  as  that  of  the  scrotum  and  the  eyehds.  In  this 
respect  it  contrasts  remarkably  with  the  thick  hairy  skin  which  covers  the-  cushion  of 
adipose  tissue  situated  over  the  symphysis  ;  it  is  generally  of  a  browner  colour  than  that 
of  the  rest  of  the  skin ;  it  has  no  hair  bulbs  visible  to  the  naked  eye ;  it  is  extremely 
movable,  being  capable  of  gliding  forward  upon  the  corpus  cavemosum,  of  forming  a 
covering  for  tumours  in  the  scrotvun,  and  also  of  folding  upon  itself  when  the  penis  is  re- 
duced to  its  smallest  dimensions.  This  great  mobility  of  the  skin  is  owing  to  the  loose- 
ness of  the  sub-cutaneous  cellular  tissue,  which  is  continuous  with  the  dartos,  and  ap- 
pears to  me  to  be  of  the  same  nature ;  like  that  structure,  it  never  contains  fat,  but  may 
become  infiltrated  with  serum. 

The  Prepuce. — The  skin  of  the  penis  forms  a  non-adherent  sheath  for  the  glans,  upon 
Avhich  it  advances,  and  either  projects  beyond  it  or  not,  according  as  that  part  is  flaccid 
or  distended.  At  the  free  border  of  this  sheath  the  skin  does  not  terminate  abruptly,  but 
is  reflected  upon  itself,  assumes  the  characters  of  a  mucous  membrane,  and  passes  back- 
ward as  far  as  the  base  of  the  glans,  so  as  to  hne  the  inner  surface  of  the  cutaneous  layer. 
Opposite  the  constriction  or  neck  surrounding  the  glans,  the  mucous  membrane  or  re- 
flected skin  again  becomes  reflected  over  the  glans,  to  which  it  forms  a  closely  adherent 
covering,  and  at  the  margin  of  the  orifice  of  the  urethra  becomes  continuous  with  the 
mucous  membrane  hning  that  canal.  The  non-adherent  sheath  which  covers  the  glans 
is  called  the  prepuce.* 

Sometimes  the  orifice  of  this  sheath  is  so  narrow  as  to  prevent  its  being  easily  drawn 
backward,  especiedly  during  erection.  This  constitutes  what  is  called  phymosis.i  Cir- 
cumcision, an  operation  which  consists  in  removing  an  annular  portion  of  the  prepuce, 
was,  as  we  know,  a  general  custom  among  the  Jews,  and  is  now  recognised  among  the 
operations  of  surgery. 

The  length  of  the  prepuce  varies  in  difierent  individuals ;  in  some  it  is  very  short,  and 
only  covers  one  half  of  the  posterior  third  of  the  glans. 

The  term  franum  praputii  is  applied  to  a  triangular  fold  of  mucous  membrane,  which 
is  reflected  from  the  prepuce  upon  the  furrow  on  the  lower  surface  of  the  glans,  below 
the  urethral  orifice.  Sometimes  the  prolongation  of  the  fraenum  as  far  as  the  orifice 
renders  erection  painful,  and  requires  a  slight  operation,  called  section  of  the  fraenum. 

The  cellular  tissue,  between  the  cutaneous  and  mucous  layers  of  the  prepuce,  par- 
takes of  the  characters  of  the  sub-cutaneous  cellular  tissue  of  the  penis ;  its  looseness 

*  [Beneath  the  mncous  membrane  covering  the  constriction  behind  the  corona  glandis  are  situated  clusters 
of  small  sebaceous  glands,  named  glandule  Tysoni,  or  odorifera.'] 

t  When  this  malformation  exists,  if  the  prepuce  he  drawn  back  over  the  base  of  the  glans,  it  cannot  be  re 
turned  ;  this  comlition  of  the  parts,  and  the  sort  of  strangulation  resulting  from  it,  constitutes  what  is  known 
by  the  name  of  para-phymosis. 


THE    PENIS.  456 

enables  the  prepuce  to  be  unfolded,  and  this  takes  place  more  or  less  completely  during 
erection. 

The  Corpus  Cavemosum. — The  corpus  cavemosmn,  so  named  on  account  of  its  struc- 
ture, forms  the  greater  portion  of  the  penis  ;  it  commences  behind  by  a  bifurcated  ex- 
tremity, forming  its  roots,  or  crura.  Each  root  arises  immediately  on  the  inside,  and 
above  the  tuberosity  of  the  ischium,  by  a  very  slender  extremity,  and  gradually  increas- 
ing in  size,  passes  forward  and  inward  along  the  ascending  ramus  of  the  ischium  and 
the  descending  ramus  of  the  pubes,  to  both  of  which  it  adheres  intimately.  At  the  sjrm- 
physis  the  two  roots  unite.  The  triangular  interval  between  them  is  occupied  by  the 
canal  of  the  urethra. 

The  corpus  cavemosum  results,  therefore,  from  the  union  of  two  distinct  conical 
roots ;  and  on  this  account  the  older  anatomists  distinguished  two  corpora  cavernosa ;  but 
the  communications  existing  between  its  two  halves  are  opposed  to  any  such  distinction. 

The  corpus  cavemosum  is  cylindrical,  and  presents  a  longitudinal  groove  above,  in 
which  are  lodged  the  dorsal  vessels  and  nerves  of  the  penis,  and  a  broad  and  deep  groove 
below,  in  which  the  urethra  is  situated.  The  anterior  extremity  is  obtuse,  and  is  em- 
braced by  the  base  of  the  glans,  with  which  it  does  not  appear  to  have  any  vascular 
communication. 

Structure. — The  corpus  cavemosum  is  composed  of  a  very  strong  fibrous  cylinder, 
filled  with  a  spongy  or  erectile  tissue. 

The  Fibrous  Cylinder. — The  external  coat  is  of  a  fibrous  nature,  and  is  remarkable  for 
its  thickness,  which  is  one  or  two  lines ;  for  its  strength,  which  is  such  that  the  corpus 
cavemosum  will  bear  the  whole  weight  of  the  body  without  breaking,  as  may  be  proved 
experimentally  upon  the  dead  body ;  and  for  its  extensibility  and  elasticity,  properties  which 
do  not  belong  intrinsically  to  the  tissue  itself,  but  depend  upon  the  areolar  disposition  of 
its  fibres.* 

Septum  of  the  Corpus  Cavemosum. — The  interior  of  the  cavernous  body  is  divided  into 
two  lateral  halves  by  an  incomplete  septum,  formed  of  very  strong  vertical  fibrous  col- 
umns, which  are  much  thicker  and  more  numerous  behind  than  in  front.  This  median 
septum  (septum  pectiniforme,  h,  fig.  187),  between  the  two  halves  of  the  corpus  caver- 
nosum,  is  not  complete ;  it  appears  to  be  intended  to  prevent  too  great  a  distension  of 
this  part  during  erection.     - 

The  Spongy  or  Erectile  Tissue. — An  areolar  tissue  (a  a),  the  meshes  of  which  contain 
a  greater  or  less  quantity  of  blood,  occupies  the  interior  of  the  fibrous  cylinder  of  the 
corpus  cavemosum.  This  tissue,  which  is  the  chief  agent  in  erection,  consists  of  an 
interlacement  of  veins,  supported  by  prolongations  or  trabecule,  given  off  from  the  inner 
surface  of  the  fibrous  membrane. 

If  air  or  any  fluid  be  injected  into  the  crura  of  the  corpus  cavemosum,  the  penis  will 
acquire  the  same  size  as  it  has  during  erection,  and  the  injection  will  pass  readily  into 
the  veins ;  we  may  therefore  conclude  that  all  the  cells  of  the  corpus  cavemosum  com- 
municate with  each  other,  and,  farther,  that  they  communicate  freely  with  the  veins 
If  the  corpus  cavemosum  be  distended  with  tallow,  and  then,  after  being  allowed  to  dry, 
if  the  injection  be  dissolved  out  by  hot  oil  of  turpentine,  we  shall  find  that  the  cavernous 
body  presents  a  spongy  stmcture,  analogous  to  that  of  the  spleen.  The  several  grada- 
tions from  tme  veins  to  spongy  tissue  may  be  traced  in  the  venous  plexus,  situated  at 
the  root  of  the  penis.  At  first  we  find  veins  communicating  with  each  other  laterally,  as 
it  were,  by  perforations ;  then  the  communications  become  more  and  more  numerous ; 
and,  lastly,  in  the  corpus  cavemosum  all  traces  of  distinct  vessels  are  lost,  and  nothing 
can  be  detected  but  a  mass  of  cells,  apparently  resulting  from  the  anastomoses  of  veins. 
The  structure  of  the  spongy  tissue  of  the  corpus  cavemosum  is,  therefore,  essentially 
venous. 

A  transverse  section  of  the  corpus  cavemosum  (^.  187),  after  it  has  been  prepared 
in  the  manner  above  indicated,  exhibits  an  appearance  of  cells, 
somewhat  resembling  that  seen  on  a  section  of  the  body  of  a  ver- 
tebra ;  these  cells  are  bounded  by  laminae,  which  appear  to  be 
chiefly  derived  from  the  lower  wall  of  the  corpus  cavemosum,  on 
the  inner  surface  of  which  is  found  a  convexity,  corresponding 
with  the  groove  for  the  urethra  {d).  These  laminae  radiate,  as 
from  a  centre,  to  the  entire  internal  surface  of  the  cyhnder,  repre- 
sented by  the  corpus  cavemosum. 

Vessels. — The  veins  of  the  corpus  cavemosum  are  extremely 
large,  and  are  divided  into  the  dorsal  veins  of  the  penis  and  the    o'/ 
proper  veins  of  the  cavemous  body ;  they  all  pass  beneath  the 
symphysis,  and  are  received  into  fibrous  canals,  through  which 
they  are  transmitted  into  the  pelvis.    These  veins  are  provided  with  a  great  number  of 
valves,  so  that  injections  thrown  into  the  trunks  cannot  pass  into  the  branches. 

*  [The  outer  coat  of  the  corpus  cavemosum  and  the  trabecule,  in  its  interior,  consist  of  tendinous  fibres, 
mixed  with  some  elastic  tissue.  In  the  penis  of  the  horse  there  are  pale  red  fibres,  differiu?  from  cellular 
tendinous,  and  elastic  tissue,  but  which,  according  to  Miiller,  do  not  possess  muscular  contractility.] 


456  SPLANCHNOLOGY. 

The  arteries  arise  from  the  internal  pudic,  and  enter  the  substance  of  the  corpus  ca 
vemosum.  Injection  of  these  arteries  does  not  produce  erection  until  the  fluid  has  pass- 
ed from  them  into  the  veins.* 

The  lymphatic  vessels  are  little  known. 

No  nerves  have  been  traced  into  the  interior  of  the  corpus  cavemosum.t 

The  Triangular  Suspensory  Ligament  of  the  Penis. — This  ligament  is  composed  of  yel- 
low elastic  tissue,  and  extends  in  the  median  hne  from  the  symphysis  pubis  to  the  cor- 
pus cavemosum.  Muscular  fibres  have  been  described  as  existing  in  it ;  but  it  is  prob- 
able some  fibres  prolonged  from  the  bulbo-cavernosus,  and  now  known  as  the  muscle 
of  Houston,  have  been  regarded  as  forming  part  of  this  ligament.  I  have  seen  the  sus- 
pensory ligament  reach  along  the  linea  alba,  half  way  up  to  the  umbilicus. 

Muscles  of  the  Penis. 
These  are  eight  in  number,  four  on  each  side,  viz.,  the  ischio-cavernosus,  the  bulbo-ca- 
vernosus, the  pubio-urethralis,  and  the  ischio-bulbosus. 

The  Ischio-cavernosus,  or  the  Erector  Penis. 

The  ischio-cavernosus  {c,Jig.  163)  is  an  elongated  muscle,  situated  upon  the  corre- 
sponding root  of  the  corpus  cavemosum  ;  it  is  curved  upon  itself,  and  is  aponeurotic  in 
part  of  its  extent. 

It  arise*  from  the  inner  lip  of  the  tuberosity  of  the  ischium,  below  the  transversus  pe- 
rinaei,  by  tendinous  and  fleshy  fibres,  and  also  from  the  surface  of  the  root  of  the  corpus 
cavemosum.  From  these  points  its  fibres  pass  inward,  and  are  inserted,  after  a  short 
course,  into  the  edges  of  the  upper  surface  of  a  very  strong,  shining,  and  fasciculated 
aponeurosis,  having  its  fibres  directed  from  behind  forward,  which  covers  the  correspond- 
ing root  of  the  cavernous  body,  upon  which  it  is  then  prolonged.  The  fleshy  fibres,  ter- 
minating at  the  edges  of  the  aponeurosis,  form  two  bundles  ;  one  internal,  and  extend- 
ing upon  the  inner  side  of  the  root,  the  other  extemal,  which  passes  on  the  outer  side 
of  the  same,  and  is  prolonged,  much  farther  than  the  internal  fasciculus,  upon  the  cav- 
ernous body.  In  order  to  see  the  structure  of  this  muscle,  it  is  necessary  to  make  a 
longitudinal  incision  into  the  aponeurosis,  which  entirely  covers  its  lower  surface  ;  we 
then  observe  a  muscular  layer,  which  is  tolerabjy  thick  behind,  but  thin  in  front,  and  is 
formed  partly  by  the  original  fibres,  and  pertly  by  others  arising  from  the  root  of  the 
corpus  cavemosum  itself 

Relations. — Below,  with  the  cellular  tissue  and  the  dartos  ;  above,  with  the  root  of  the 
corpus  cavemosum,  upon  which  it  is  closely  applied  ;  on  the  inside,  with  the  bulbo-cav- 
ernosus, being  separated  from  it  by  a  triangular  space,  the  base  of  which  is  directed 
backward. 

Uses. — It  acts  solely  upon  the  corpus  cavemosum,  drawing  the  root  of  the  penis  down- 
ward and  backward  •  instead  of  compressing  the  root  of  the  corpus  cavemosum  by  the 
contraction  of  its  fibres,  it  tends,  on  the  contrary,  to  dilate  its  cavity,  by  separating  the 
wer  from  the  upper  wall,  and,  in  this  manner,  facilitates  erection. 

The  Bulbo-cavernosus,  or  Accelerator  Urince. 

This  muscle  {d,fig.  163)  is  much  larger  than  the  preceding  ;  it  is  situated  in  front  of 
the  anus,  extending  along  the  lower  surface  of  the  bulb  and  the  spongy  portion  of  the 
urethra,  upon  which  it  seems  to  be  moulded. 

It  arises  in  front  of  the  sphincter  ani  by  a  median  fibrous  raphe,  which  is  common  to 
the  two  muscles  of  this  name,  and  which  appears  to  arise  from  the  bulb,  to  which  it  ad 
heres  closely ;  while  the  exteraed  fibres  arise  from  the  posterior  margin  of  the  triangu- 
lar ligament,  or  deep  perineal  fascia,  and  frequently  from  the  rami  of  the  ossa  pubis,  op- 
posite that  margin.  From  this  double  origin  the  fibres  pass  forward,  and  terminate  in 
the  following  manner :  the  outermost  fibres  form  a  thin  layer  upon  the  lower  surface  of 
the  triangular  ligament,  and  are  inserted  by  short,  tendinous  fibres  to  the  inner  side  of  the 
root  of  the  corpus  cavemosum  ;  the  middle  fibres,  which  are  larger,  are  directed  oblique- 
ly inward,  and  are  inserted  by  very  distinct  tendinous  fibres  immediately  in  front  of  the 
jtoint  of  junction  of  the  roots  of  the  corpus  cavemosum,  in  the  sort  of  groove  between 
that  body  and  the  urethra ;  the  innermost  fibres  are  the  longest ;  they  pass  directly  for- 

*  [Miiller  has  described,  besides  the  nutritious  arteries  of  the  corpus  cavemosum,  which  terminate,  as  usual, 
ill  the  veins,  a  peculiar  set  of  vessels,  called  the  arterite  helicina.  They  are  short,  curled  branches,  much 
larger  than  capillaries,  and  ending  abruptly  in  free  rounded  extremities  ;  they  project  either  singly,  or  in  tufts 
arising  ii-om  one  stem,  into  the  venous  cells,by  the  lining  membrane  of  which  they  are  supported  and  invested. 
They  are  found  principally  in  the  posterior  portions  of  the  cavernous  and  spongy  bodies,  and  are  more  marked 
in  man  than  in  animals.  In  the  horse  they  are  very  indistinct ;  in  the  elephant  they  do  not  exist  at  all.  Miil- 
ler believes  that  the  blood,  during  erection,  is  poured  out  directly  from  these  vessels  into  the  venous  cells  ; 
but  no  openings  through  which  the  blood  could  escape  have  been  detected,  either  in  their  sides  o--  at  their  ex 
tremities,  nor  is  analogy  in  favour  of  their  existence. 

According  to  Valentin,  the  so-called  helicine  arteries  are  the  divided  branches  of  common  arteries  curled  up 
(after  having  been  injected),  in  consequence  of  the  retraction  of  the  elastic  trabeculie  on  which  they  are  sup- 
ported ;  to  this  it  is  replied,  by  Miiller,  that  these  vessels  may  be  seen  in  cells  deeper  than  the  surface  o;  the 
lection.     Valentin  farther  maintains  that  the  arteries  terminate  in  the  veins  by  wide,  funnel-shaped  orifices.] 

t  [Numerous  nerves  enter  the  corpus  cavemosum;  they  arc  derived  from  the  internal  pudic  and  sympatheV 
ic  nerves,  and  have  been  carefully  traced  by  Mtiller.l 


THE    URETHRA.  45^ 

ward,  and,  at  the  point  where  the  penis  is  bent  in  front  of  the  pubis,  are  inflected  out- 
ward ie,fig.  163),  pass  upon  the  sides  of  the  penis,  and  terminate  on  its  dorsal  surface, 
becoming  continuous  with  the  suspensory  ligament.  Tlie  last-named  termination  ap- 
pears to  me  to  constitute  the  muscle  described  by  Houston,  which,  according  to  that 
anatomist,  is  intended  to  compress  the  dorsal  veins  of  the  penis*  in  man  and  other  ani- 
mals ;  but  it  is  evident,  on  the  one  hand,  that  it  cannot  compress  the  veins  of  the  penis ; 
and,  on  the  other,  as  M.  Lenoir  has  pointed  out,  that  the  dorsal  veins  of  the  penis  are 
cutaneous  veins,  which  do  not  communicate  with  those  of  the  corpus  cavemosum.t 

Relations. — I3elow,  the  bulbo-cavernosus  corresponds  with  the  dartos,  from  which  it  is 
separated  by  the  superficial  perineal  fascia  by  a  very  thin  layer  of  fat,  and  by  a  proper 
fibrous  sheath.  Above,  it  is  in  relation  with  the  bulb  of  the  urethra,  which  it  embraces, 
like  a  contractile  sheath,  resembling  the  sheath  around  the  stems  of  grasses.  The  inner 
border  is  continuous  with  the  muscle  of  the  opposite  side  ;  so  that,  at  first  sight,  it  might 
be  thought  that  there  is  but  one  bulbo-cavernosus. 

Uses. — Its  attachment  to  the  inner  side  of  the  corpus  cavemosum  enables  it  to  separ- 
ate the  lower  wall  of  that  body  from  the  upper,  and,  consequently,  to  induce  the  entrance 
of  the  blood.  It  therefore  contributes  powerfully  to  erection.  On  the  other  hand,  by 
compressing  the  urethra,  it  accelerates  the  expulsion  of  the  urine  and  semen. 

The  Puhio-urethralis. 
This  muscle,  known  also  as  the  muscle  of  Wilson,  because  it  was  described  by  that  anat- 
omist, may  be  regawied  as  the  continuation  of  the  levator  ani.  The  two  nmscles  arise 
from  the  middle  of  the  sub-pubic  arch,  and  descend  first  upon  the  sides  and  then  on  the 
lower  surface  of  the  membranous  portion  of  the  urethra,  which  they  surround  as  in  a 
ring.  They  are  situated  behind  the  triangular  ligament,  or  deep  perineal  fascia.t  When 
spasmodically  contracted,  it  is  said  that  they  may  arrest  the  point  of  a  catheter. 

The  Ischio-bulbosus. 
We  may  describe  under  this  name  a  small  muscle  situated  below  the  deep  perineal 
fascia.  It  is  stronger  than  the  transversus  perinaei ;  it  arises  from  the  ascending  ramus 
of  the  ischium  and  the  descending  ramus  of  the  pubis,  and  terminates  on  the  sides  of  the 
bulb.  This  muscle,  which  is  of  a  triangular  shape,  is  separated  from  the  one  last  de- 
scribed by  the  deep  perineal"  fascia,  so  that  it  cannot  be  regarded  as  a  dependance  of  the 
levator  ani.<J 

The  Urethra. 

The  urethra  is  the  excretory  passage  for  the  urine,  and  in  the  male  it  serves  the  same 
purpose  in  regard  to  the  semen. 

Its  direction  has  been  particularly  studied.  Commencing  at  the  neck  of  the  bladder, 
it  passes  forward  and  downward  ;  having  arrived  beneath  the  s3Tnphysis  pubis,  it  de- 
scribes a  slight  curve,  with  the  concavity  directed  upward,  embraces  the  symphysis,  ri- 
ses a  little  in  front  of  it,  and  then  enters  the  groove  on  the  lower  surface  of  the  corpus 
cavemosum.    Beyond  this  point  its  direction  is  determined  by  that  of  the  penis ;  and  it 

*  [The  compressores  venae  dorsalis  penis,  according  to  Houston  (Dublin  Hasp.  Reports,  vol.  v.),  arise  from 
the  rami  of  the  pubes  above  the  erectores  penis  and  the  crura  of  the  corpus  cavemosum,  expand  into  a  thin 
layer,  pass  upward,  inward,  and  forward,  and  unite  in  a  common  tendinous  band  over  the  dorsal  vein.  They 
ftre  separated  by  the  crura  from  the  erectores  penis,  of  which  muscles,  he  says,  they  might  otherwise  be  re- 
garded as  portions  :  the  anterior  layer  of  the  triangular  ligament  and  the  pudic  artery  are  interposed  between 
them  and  the  muscles  of  Wilson.] 

t  Dissertation  sur  quelques  Points  d'Anatomie,  de  Physiologic,  et  de  Pathologic,  No.  cccxv.,  1833. 

[The  dorsal  veins  return  the  greater  part  of  the  blood  from  the  glans  penis  and  corpus  spongiosum,  as  well 
as  the  skin,  and  are  also  joined  by  branches  from  the  corpus  cavemosum.  (See  M.  Cruveilhier's  own  descrip- 
tion of  these  veins,  Anoeiologt).] 

t  [In  the  description  of  the  muscles  given  by  Wilson  himself  (Med.  Chir.  Trans.,  vol.  i.,  p.  176,  177),  it  is 
■tated,  that  "  the  line  of  tendon  connecting  the  two  bellies  of  these  muscles  is,  in  general,  very  distinctly  seen 
running  from  the  apex  of  the  prostate  gland,  along  the  under  surface  of  the  membranous  portion  of  the  ure- 
thra, until  it  enters  the  corpus  spongiosum  penis."  From  this  it  would  appear  that  the  muscles  discovered  by 
him  are  placed  between  the  two  layers  of  the  ligament,  not  behind  its  posterior  layer. 

On  the  same  plane  with  Wilson's  muscles,  i.  e.,  between  the  layers  of  the  ligament,  are  situated  two  small 
transverse  muscles,  which  arise,  one  on  each  side,  by  broad  thin  tendons,  from  the  rami  of  the  ischia,  near 
their  junction  with  those  of  the  ossa  pubis,  immediately  above  the  crura  penis  and  their  erector  muscles  ;  from 
thence  the  fleshy  fibres  pass  transversely  inward  and  upward,  and  are  inserted  along  the  median  line  of  the 
upper  and  under  surface  of  the  membranous  portion  of  the  urethra  by  means  of  two  tendinous  structures, 
which  extend,  one  above  the  urethra,  from  the  fascia  covering  the  prostate  to  the  union  of  the  crura  penis  in 
frjnt;  of  the  triangular  ligament,  and  the  other  below  that  canal,  from  the  fascia  on  the  prostate  to  the  central 
poirt,  of  the  perineum  :  to  this  tendinous  structure  the  vertical  muscles  of  Wilson  are  also  attached.  The  pu 
die  a'.teries  run  either  above  or  below  these  transverse  muscles,  the  lower  fibres  of  which  pass  below  Cow- 
per's  glands,  i.  e.,  more  superficially,  when  viewed  from  the  perineum. 

These  transverse  muscles  are  described  and  figured  by  Santorini  (Observ.  Anat.,  c  x.,  I)  viii.,  t.  3,  fig.  5, 
also,  Septemdecim  Tabula,  t.  16,  fig.  1),  who  states,  however,  that  Ihey  are  attached  only  to  the  lower  surface 
of  tlie  urethra,  behind  the  bulb ;  he  named  them  elevatores  urethrue,  or  ejaculatores.  It  has  been  recently 
shown  by  Mr.  Guthrie  (Land.  Med.  and  Surg.  Journ.,  1833,  p.  491,  492 ;  also,  On  the  Anatomy  and  Diseases 
of  the  Neck  of  the  Bladder  and  of  the  Urethra,  1834,  p.  34,  &c.)  that  the  transverse  muscles  of  Santorini 
are  inserted,  as  already  described,  both  above  and  below  the  urethra  ;  and  that  the  vertical  muscles  of  Wilson 
are  blended  with  them  at  their  insertions  :  he  therefore  proposes  to  regard  them  as  one  muscle,  which  has 
been  termed  the  compressor  urethra:.'] 

^  [The  description  of  this  muscle  corresponds  exactly  with  that  of  the  transversus  perinmi  alter  of  Albinus.l 

M  M  M 


458  SPLANCHNOLOGY. 

describes,  with  that  organ,  a  second  curve,  much  more  marked  than  the  preceding,  hav- 
ing its  concavity  directed  downward,  but  only  in  the  state  of  relaxation,  for  the  curve  no 
longer  exists  when  the  penis  becomes  elongated,  either  from  erection,  or  from  direct 
traction. 

It  follows,  therefore,  that,  except  during  erection,  the  urethra  describes  two  curves, 
like  the  letter  S  ;*  but  when  the  penis  is  elongated,  it  forms  only  a  single  curve,  which 
is  permanent. 

Although  the  curvature  of  the  urethra  is  not  so  rigid  as  to  prevent  the  introduction  of 
a  straight  instrument  into  the  bladder,  it  would  be  wrong  to  conclude  that  the  canal  it- 
self is  straight.  It  must  be  remembered  that  organic  membranous  ducts  are  sufficiently 
pUable  to  accommodate  themselves  to  the  direction  of  instruments  introduced  into  them ; 
but  the  effacing,  or  the  artificial  removal  of  the  curves,  is  very  different  from  their  non- 
existence. Moreover,  the  curvature  of  the  urethra  is  demonstrated  by  the  impossibility 
of  drawing  a  straight  line  from  the  neck  of  the  bladder,  and  passing  a  short  distance  be- 
low the  symphysis  to  the  point  where  the  urethra  joins  the  corpus  cavernosum ;  also  by 
the  curve  acquired  by  bougies  after  remaining  for  some  time  in  the  urethra ;  and,  lastly, 
by  the  curvature  presented  by  a  mould  obtained  by  injecting  the  bladder  and  urethra 
with  any  substance  capable  of  becoming  solid. 

Dimensions. — The  length  of  the  urethra  is  from  eight  to  nine  inches  ;  it  is  sometimes 
less  than  eight.  The  extreme  dimensions  noticed  by  Whately,t  in  measurements  taken 
from  forty-eight  subjects,  are  nine  inches  six  lines  and  seven  inches  six  lines.  It  is  dif- 
ficult to  estimate  the  width  of  the  urethra.  According  to  Home,  it  is  four  lines,  except 
at  the  orifice,  where  it  is  only  three.  It  is  quite  impossible  to  judge  of  its  width  exter- 
nally, on  account  of  the  thickness  of  its  walls,  and  especially  on  account  of  their  being 
unequal.  The  extreme  dilatability  of  the  canal  allows  the  introduction  of  instnmients 
of  considerable  caliber,  as  in  the  operation  of  lithotrity. 

The  urethra  is  considered  as  divided  into  three  portions,  as  different  in  their  structure 
as  in  their  relations  ;  these  are  the  prostatic,  the  membranous,  and  the  spongy  portions. 

The  Prostatic  Portion. — This  part  of  the  urethra,  which  forms,  as  it  were,  a  continua- 
tion of  the  bladder,  and  the  commencement  of  the  urethra,  is  called  prostatic,  because  it 
appears  to  be  hollowed  out  of  the  glandular  body  called  the  prostate,  the  description  of 
which  must  be  inserted  here,  on  account  of  its  intimate  connexion  with  the  urethra. 

The  prostate  {i,fig.  181),  a  whitish  glandular  body,  is  situated  in  front  of  the  neck  of 
the  bladder,  and  embraces  it ;  it  is  behind  the  symphysis  pubis,  and  in  front  of  the  rec- 
tum. It  is  shaped  like  a  cone,  with  its  base  turned  backward,  and  its  truncated  apex 
forward.  Its  axis  or  long  diameter  is  horizontal,  but  slopes  a  little  from  behind  down- 
ward and  forward.  It  has  often  a  bi-lobed  appearance  in  man,  but  it  is  never  truly 
double,  as  in  a  great  number  of  animals. 

The  size  of  the  prostate  varies  greatly  in  different  subjects.  The  following  dimen- 
sions have  been  taken  from  the  measurements  of  the  prostates  of  adults  :  Vertical  di- 
ameter, twelve  lines  ;  transverse,  eighteen  ;  antero-posterior,  or  length,  fifteen.  Some- 
times it  acquires  three  or  four  times  its  nominal  size  ;  the  increase  may  affect  either  the 
whole  gland  or  one  half,  or  the  middle  lobe  only. 

Relatione. — We  shall  examine  the  relations  of  the  prostate  with  the  parts  correspond- 
ing to  its  outer  surface,  and  with  those  which  are  situated  within  it. 

Relations  of  the  Outer  Surface  of  the  Prostate. — The  lower  surface  corresponds  with  the 
rectum,  adhering  to  it  by  tolerably  dense  celluleir  tissue,  in  which  there  is  never  any  fat 
or  serum  ;  and  hence"^he  rule  of  examining  the  prostate  by  the  rectum.  In  consequence 
of  alterations  in  the  condition  of  the  rectum,  that  intestine  sometimes  projects  on  each 
side  beyond  the  prostate,  as  during  distension ;  and  sometimes,  as  when  it  is  contract- 
ed, the  prostate  projects  beyond  it  laterally.  The  lower  surface  of  the  gland  is  smooth, 
and  is  traversed  in  the  median  line  by  an  antero-posterior  furrow,  which  is  well  marked 
in  some  subjects,  and  divides  it  into  two  equal  portions. 

The  upper  surface  is  in  relation  with  the  recto-vesical  fascia  {q,fig-  1^1)>  <""'  rather, 
with  some  very  strong  ligamentous  bundles,  which  extend  from  the  pubes  to  the  blad- 
der, and  are  called  the  ligaments  of  the  bladder.  This  surface  has  no  immediate  rela- 
tions with  the  arch  of  the  pubes,  behind  which  it  is  placed ;  it  is  always  some  lines  dis- 
tant from  it.  Nevertheless,  by  means  of  a  silver  catheter  or  sound,  introduced  into  the 
bladder,  we  may  draw  the  prostate  under  the  pubes,  and  make  it  project  in  the  perineum. 

The  sides  are  embraced  by  the  levator  ani  and  the  levator  prostatae.  When  the  prostate 
is  pushed  downward  by  the  catheter,  its  sides  are  embraced  by  the  circumference  of 
the  arch  of  the  pubes,  and  they  then  approach  very  near  the  trunk  of  the  internal  pudic 
artery. 

The  base  of  the  prostate  embraces  the  neck  of  the  bladder,  and  is  prolonged  a  little 
upon  that  organ,  so  as  to  surround  the  vas  deferens  and  the  neck  of  the  vesiculffi  semi- 
nales. 

*  It  was  this  direction  of  the  canal  which  suggested  to  J.  L.  Petit  the  idea  of  making  silver  bougies,  shaped 
like  the  letter  S,  to  remain  in  the  passage. 
t  An  Improved  Method  of  treating  Stricture  of  the  Urethra,  1816. 


THE    URETHRA.  43^ 

The  apex  terminates  behind  the  membranous  portion  of  the  urethra. 

Relations  of  the  Prostate  vsith  the  Parts  situated  in  its  Interior. — The  prostate  is  perfo- 
rated by  the  urethra,  by  the  ejaculatory  ducts,  and  by  its  own  excretory  ducts. 

The  relations  of  the  urethra  with  the  prostate  vary  in  different  subjects  :  thus,  sometimes 
its  lower  three  fourths  only  are  surrounded  by  the  gland,  which  is  accordingly  wanting 
above,  and  is  merely  grooved,  not  perforated  by  a  canal ;  sometimes  the  prostate  forms 
a  complete  hollow  cylinder  around  the  urethra.  The  portion  of  the  prostate  situated 
above  the  urethra  is  scarcely  ever  thicker  than  the  part  beneath  it.  In  some  cases, 
however,  the  urethra  has  been  found  occupying  the  lower  part  of  the  prostate,  and  only 
separated  from  the  rectum  by  a  very  thin  layer  of  glandular  substance.  When  such  is 
the  case,  the  rectum  is  very  liable  to  be  wounded  in  the  different  steps  of  the  operation 
of  lithotomy.* 

In  the  natural  state  the  prostate  does  not  project  into  the  urethra ;  but  not  unfrequent- 
ly  we  find  a  prominence,  of  greater  or  less  size,  rising  from  the  lower  part  of  the  urethra, 
opposite  the  base  of  the  prostate,  and  obstructing  more  or  less  completely  the  com- 
mencement of  that  canal :  this  tubercle  was  named  by  Lieutaud  la  luette  visicale  {uvula 
vesica) ;  by  Sir  Everard  Home,  an  enlargement  of  the  middle  lobe  of  the  prostate.  But, 
in  the  first  place,  this  prominence  only  exists  in  disease  ;  and,  secondly,  there  is  no 
middle  lobe,  unless  that  term  be  applied  to  the  slightly-grooved,  and,  therefore,  thinner 
portion  by  which  the  two  lateral  halves  of  the  prostate  are  united. 

Relations  of  the  Ejaculatory  Ducts  with  the  Prostate. — The  ejaculatory  ducts  (d,fig. 
186),  which  lie  close  to  each  other,  are  received  into  a  sort  of  conical  canal,  formed  in 
the  prostate.  Some  loose  cellular  tissue  separates  them  from  the  substance  of  the  gland, 
of  which  they  are  altogether  independent ;  it  was  chiefly  to  the  portion  of  the  prostate 
which  is  situated  above  this  canal  that  the  name  middle  lobe  was  given  by  Home. 

Density. — The  density  of  the  prostate  is  considerable,  and  yet  the  tissue  of  this  gland 
is  friable,  and  can  be  very  easily  torn  after  having  been  once  divided.  It  is  of  the  greatest 
importance  to  remember  this  friability  in  performing  the  operation  of  lithotomy.  The 
prostate,  in  fact,  is  the  only  obstacle  to  the  extraction  of  the  calculus ;  and  when  this 
gland  has  been  divided  in  its  antero-posterior  diameter,  the  bladder  itself  may  be  torn 
with  the  greatest  facility. 

Structure. — The  structure  of  the  prostate  can  only  be  properly  studied  in  the  adult. 
In  certain  cases  of  hypertrophy  without  alteration  of  tissue,  its  characters  are,  as  it 
were,  exaggerated.  It  consists  of  a  collection  of  glandular  lobules,  which  may  be  subdi- 
vided into  granules  pressed  close  to  each  other  in  the  midst  of  a  tissue  that  appears  to 
me  to  be  muscular,  for  it  is  continuous  with  the  muscular  coat  of  the  bladder,  and  bears 
the  most  perfect  resemblance  to  it  in  cases  of  hypertrophy.  From  these  granules,  which 
are  generally  of  unequal  size,  small  excretory  ducts  proceed,  and  unite  into  an  irregular 
number  of  prostatic  ducts  that  open,  not  upon  the  verumontanwn  itself,  but  upon  its  sides 
{see  fig.  182),  in  the  whole  extent  of  the  lower  wall  of  the  prostatic  portion  of  the  ure- 
thra, or  prostatic  sinus.  I  have  assured  myself  of  the  existence  of  these  ducts  and  their 
orifices  in  many  cases  where  I  have  found  them  filled  with  innumerable  small  calculi, 
resembling  grains  of  brownish  sand.  The  orifices  of  the  prostatic  ducts  may  be  easily 
detected  by  pressing  the  gland,  when  the  fluid  secreted  by  it  will  be  observed  to  exude 
at  several  points. 

The  Membranous  Portion. — The  membranous  portion  of  the  urethra  (c,fig.  181)  ex- 
tends from  the  prostatic  portion  to  the  bulb,  and  passes  upward  and  forward.!  It  is  in 
relation  above  and  laterally  with  the  arch  of  the  pubes,  from  which  it  is  separated  by 
some  considerable  veins,  or,  rather,  by  a  sort  of  erectile  tissue ;  below  it  corresponds 
with  the  rectum,  but  is  separated  from  it  by  a  triangular  space,  having  its  base  directed 
forward  and  downward,  and  its  apex  backward  and  upward.  It  is  generally  in  this  tri- 
angular space  that  the  urethra  is  divided  in  the  operation  of  lithotomy. 

Its  upper  concave  surface  is  about  an  inch  long ;  its  lower  surface  is  from  four  to  six 
lines.  This  difference  in  length  is  caused  by  the  bulb  projecting  backward  upon  the 
lower  surface  of  the  membranous  portion  of  the  urethra. 

This  part  of  the  canal  is  embraced  laterally  and  below  by  the  two  muscular  bundles 
which  have  been  already  described  as  the  muscles  of  Wilson ;  and  also  by  the  transverse 
muscular  fasciculi  described  by  Santorini  and  Guthrie. 

The  Spongy  Portion. — The  spongy  portion  {I)  constitutes  the  greatest  part  of  the  length 
of  the  urethra  ;  it  commences  opposite  the  symphysis  pubis  by  a  very  considerable  ex- 
pansion, called  the  bulb  (below  I),  and  terminates  at  the  extremity  of  the  penis  by  an- 
other and  still  larger  expansion,  which  constitutes  the  glans  penis. 

*  The  varieties  in  the  situation  of  the  urethra,  in  relation  to  the  prostate,  were  yreU  pointed  out  by  M. 
Senn,  in  an  inaugural  dissertation  in  1825.  According  to  his  observations,  the  portion  of  the  prostate  situ- 
ated below  the  canal  is  seven  or  eight  lines  thick  in  the  middle,  and  ten  or  eleveu  lines  when  measured  down- 
ward and  outward. 

t  [The  membranous  portion  perforates  both  layers  of  the  triangular  ligament,  about  an  inch  below  the  arch 
of  the  pubes  {see  Jig.  138)  ;  but  as  the  two  layers  are  separated  from  each  other  below,  the  greater  part  of 
this  portion  of  the  urethra  is  included  between  them  ;  a  very  small  part  is  situated  behind  the  posterior  laver 
both  layers  are  prolonged  over  the  urethra,  one  forward  and  tlie  other  backward.] 


400  '   SPLANCHNOLOGY. 

The  hdb  occupies  the  highest  part  of  the  pilbic  arch,  and  fills  the  interval  between  the 
crura  of  the  corpus  cavemosum.  Its  size  varies  in  different  individuals,  and  according 
to  the  state  of  the  penis ;  it  projects  several  lines  below  the  level  of  the  membranous 
portion,  which  is  partially  covered  by  it  in  this  direction,  and  seems  to  open  into  its  up- 
per part. 

As  the  bulb  is  directed  very  obliquely  upward  and  forward,  we  might  be  inclined  to 
consider  the  urethra  to  be  much  more  curved  than  it  actually  is,  if  we  judged  of  it  only 
by  the  external  appearance  of  the  canal. 

The  bulb  is  embraced  below  and  upon  the  sides  by  the  bulbo-cavernosi  muscles,  which 
have  numerous  points  of  insertion  upon  it.  Between  these  muscles  and  the  bulb  we 
find  Cowper's  glands.  The  bulb  terminates  insensibly  in  front,  becoming  continuous 
with  the  spongy  portion  :  the  angle  of  union  of  the  crura  of  the  corpus  cavernosum  may 
be  assigned  as  its  anterior  boundary. 

The  Glands  of  Cowper. — These  are  two  small,  rounded  bodies  (g  g,figs.  168,  181,  182) 
(so  called  after  the  anatomist  who  has  given  the  best  description  of  them),  situated 
against  the  bulb,  in  contact  with  which  they  are  retained  by  a  tolerably  dense  layer  of 
fibrous  tissue.*  From  each  of  these  glands,  which  are  of  variable  dimensions,  an  excre- 
tory duct  proceeds,  and  after  a  course  of  an  inch  and  a  half  or  two  inches,  opens  into 
the  canal  of  the  urethra  upon  the  sides  of  the  spongy  portion  (c,  fig.  182),  passing  ob- 
liquely through  its  parietes.t 

In  front  of  the  bulb,  the  spongy  portion  of  the  urethra  enters  the  groove  on  the  lower 
surface  of  the  corpus  cavernosum,  and  is  in  relation  below,  in  the  first  part  of  its  course, 
with  the  bulbo-cavernosi  muscles,  which  separate  it  from  the  cellular  tissue  of  the  scro- 
tum, and  more  anteriorly  with  the  skin  of  the  penis. 

The  glans,  so  called  from  its  shape,  is  the  conical  enlargement  which  forms  the  ex- 
tremity of  the  penis.  It  is  covered  by  the  prepuce,  which  is  united  to  it  below  by  means 
of  the  fraenum ;  its  base  projects  considerably  beyond  the  end  of  the  corpus  cavernosum, 
and  forms  what  is  called  the  corona  glandis.  This  circular  projection  is  grooved  perpen- 
dicularly throughout  its  entire  extent  by  some  large  nervous  papillae,  which  are  visible 
to  the  naked  eye.  The  base  of  the  glans  is  cut  very  obliquely,  so  that  its  upper  surface 
is  twice  as  long  as  its  lower.  Below,  and  in  the  median  line,  the  corona  glandis  pre- 
sents a  groove,  in  which  the  fraenum  is  received. 

At  the  extremity  of  the  glans  is  situated  the  orifice  of  the  urethra,  meatus  urinarius, 
a  vertical  fissure,  three  or  four  lines  in  extent,  and  placed  in  the  same  line  as  the  frae- 
num, from  which  it  is  separated  by  a  very  short  interval.  Sometimes  this  orifice  is 
placed  exactly  opposite  the  fraenum,  and,  like  it,  is  directed  downward :  this  malforma- 
tion constitutes  what  is  called  hypospadias. 

Internal  Surface  of  the  Urethra. — Upon  this  surface  (see  fig.  182)  we  find  no  trace  of 
the  distinction  established  between  the  different  portions  of  the  urethra,  considered  from 
without,  except  that  the  prostatic  portion  of  the  canal  is  of  a  white  colour,  while  all  the 
rest  of  it  is  of  a  more  or  less  deep  violet  hue. 

Dimensions. — Opposite  the  prostate  the  urethra  becomes  dilated,  sometimes  to  a  con- 
siderable extent  (sinus  prostaticus) ;  at  the  commencement  of  the  membranous  portion 
it  suddenly  contracts,  and  then  continues  cylindrical  as  far  as  the  glans,  where  it  again 
dilates  so  as  to  form  the  fossa  navicularis  (o),  and  terminates  by  an  orifice,  which  is  the 
narrowest  part  of  the  entire  canal.J 

In  order  to  obtain  more  exact  ideas  of  the  comparative  dimensions  of  the  different 
portions  of  the  urethra,  M.  Amussat  inflated  this  canal,  and  then  carefully  removed  all 
the  structures  superadded  to  its  proper  parietes,  so  as  to  reduce  the  latter  to  the  mu- 
cous membrane  only,  and  thus  leave  them  of  almost  unifonn  thickness,  instead  of  being 
very  unequal.  According  to  this  mode  of  appreciation,  which,  however,  is  not  free  from 
objection,  he  has  shown  that  the  narrowest  part  of  the  canal  is  the  bulbous,  not  the 
membranous  portion ;  that  the  canal,  after  being  contracted  opposite  the  bulb,  again  ex- 
pands at  the  spongy  portion,  and  then  gradually  contracts  as  it  proceeds  forward.  He 
denies  the  existence  of  a  dilatation  opposite  the  fossa  navicularis ;  and  attributes  the 
dilated  appearance  of  that  part  to  the  fact  of  the  tissue  of  the  glans  being  very  dense, 
and  closely  adherent  to  the  mucous  membrane  of  the  urethra,  so  as  not  to  allow  it  to 
collapse,  like  that  of  the  other  parts  of  the  canal. 

However,  the  extreme  dilatability  of  the  walls  of  the  urethra  render  an  exact  deter- 
mination of  its  dimensions  less  important  than  might  be  imagined. 

Besides  the  extensibility  of  the  tissues,  there  is  another  anatomical  condition  which 
favours  the  extreme  dilatabihty  of  the  urethra,  viz.,  the  existence  of  longitudinal  folds 
on  the  inner  surface  of  the  canal,  which  are  effaced  by  distension.     These  folds  must 

*  [They  are  placed  between  the  two  layers  of  the  triangular  ligament :  the  transverse  musrles  of  Santorini 
cover  them  below,  am  Jhe  arteries  of  the  bulb  (e  e,Jig.  168)  cross  above  them  :  they  are  compound  glands.] 

t  I  have  never  seen  the  gland  called,  by  Litre,  the  anti-prostatic  ;  nor  have  I  seen  the  third  gland  of  Cow- 
per, which  is  said  to  be  situated  below  the  arch  of  the  pubes. 

i  [Three  dilatations  in  the  urethra  are  usually  described,  viz.,  the  prostatic  sinus,  the  sinus  of  the  bulb,  and 
the  fossa  navicularis.  The  first  and  the  third  of  these  are  described  above  ;  the  second  is  at  the  commenco 
ment  of  the  soongy  portion,  in  the  inferior  wall  of  the  urethra.! 


THE    OVARIES.  461 

not  be  confounded  with  certain  small  longitudinal  fasciculi  which  lie  beneath  the  mu- 
cous membrane  throughout  the  whole  extent  of  the  canal,  and  appear  to  me  to  be  of  a 
muscular  nature.  The  whole  of  the  inner  surface  of  the  urethra  presents  a  nmnber  of 
oblique  orifices,  which  lead  into  culs-de-sac  of  variable  depths.  These  sinuses,  the  ori- 
fices of  which  are  always  directed  forward,  are  sometimes  large  enough  to  receive  the 
extremities  of  bougies  ;  they  were  very  well  described  by  Morgagni,  and,  therefore,  they 
are  generally  called  the  sinuses  of  Morgagni.  I  have  seen  them  more  than  an  inch  long. 
No  glands  open  into  them.* 

The  Verumontanum,  or  Crest  of  the  Urethra. — The  lower  wall  of  the  membranous  por- 
tion of  the  urethra  presents,  in  the  median  line,  a  crest,  which  has  been  named  the  ve- 
rumontanum, caput  gallinaginis,  or  urethral  crest  {a  to  d).  This  crest  commences  in  front 
by  a  very  delicate  extremity ;  is  directed  backward  along  the  median  line,  and  termi- 
nates  at  the  anterior  part  of  the  prostatic  portion  by  an  enlarged  extremity  (a),  upon 
which  the  ejaculatory  ducts  open  by  two  distinct  orifices.  From  this  posterior  extrem 
ity  several  radiated  folds  proceed  on  either  side,  called  the  frcena  of  the  verumontanum, 
which  are  lost  in  the  opening  of  the  neck  of  the  bladder ;  they  were  carefully  described 
by  Langenbeck.    The  prostatic  ducts  open  at  the  sides  of  the  verumontanum. 

Structure  of  the  Urethra. — ^A  very  fine  transparent  mucous  membrane,  of  an  epidermic 
character,  lines  the  inner  surface  of  the  urethra ;  and  is  continuous,  on  the  one  hand, 
with  the  mucous  membrane  of  the  bladder,  and,  on  the  other,  with  that  covering  the 
glans.  It  is  also  continued  through  the  ejaculatory  ducts,  into  the  vasa  deferentia  and 
the  vesiculae  seminales.f 

The  structure  of  the  urethra,  as  regards  the  coats  external  to  the  mucous  membrane, 
is  not  the  same  in  the  different  portions  of  the  canal. 

In  the  prostatic  portion,  we  find  the  same  elements  as  in  the  bladder,  which  seems  as 
if  it  were  continued  into  the  cavity  of  the  prostate.  The  deepest  layer  of  the  muscular 
coat  of  the  bladder  is  prolonged  between  the  mucous  membrane  and  the  prostate,  while 
the  other  layers  form  different  planes  which  penetrate  into  the  substance  of  the  gland. 

The  membranous  portion  would  be  more  correctly  denominated  the  muscular  part  of 
the  canal,  for  it  is  surrounded  by  a  layer  of  muscular  fibres.  A  plexus  of  veins  sur- 
rounds these  muscular  fibres. 

The  spongy  portion  Q  f,fig.  182;  c,fig.  187)  has  a  similar  appearance  to  that  of  the 
cavernous  body ;  it  is  an  erectile  structure,  composed  of  a  fibrous  framework,  formed  by 
numerous  prolongations  interlaced  in  all  directions,  so  as  to  resemble  areolar  tissue.  It 
is  probable  that  the  internal  coat  of  the  veins  lines  all  the  cells,  which  contain  more  or 
less  blood,  according  to  the  state  of  the  penis. 

In  the  tissue  of  the  corpus  spongiosum,  as  well  as  in  that  of  the  corpus  cavernosum, 
are  found  longitudinal  muscular  fibres,  very  evident  to  the  naked  eye  in  the  larger  ani- 
mals, and  the  existence  of  which  appears  to  be  shown  by  the  microscope  in  the  human 
subject.  The  structure  of  the  glans  (//)  is  exactly  the  same  as  that  of  the  bulb,  only 
its  tissue  is  more  dense.  The  corpus  spongiosum  urethrae  does  not  communicate  with 
the  corpus  cavernosum,  although  at  first  sight  it  appears  to  be  nothing  more  than  a  con- 
tinuation of  it.  The  blunt  extremity  of  the  corpus  cavernosum  is  evidently  embraced 
by  the  base  of  the  glans,  but  no  communication  exists  between  the  erectile  tissue  com- 
posing these  two  bodies,  so  that  it  is  possible  to  inject  them  separately. 


THE  GENERATIVE  ORGANS  OF  THE  FEMALE. 

The  Ovaries. — The  Fallopian   Tubes. — The   Uterus. — The  Vagina. — The  Urethra. — The 

Vulva. 
The  genital  organs  of  the  female  consist  of  the  ovaries,  the  Fallopian  tubes,  the  uterus, 
the  vagina,  and  the  several  parts  forming  the  vulva.    With  these  we  may  include  the 
mammae,  as  appendages  to  the  generative  apparatus. 

The  Ovaries. 

The  ovaries  {ovaria),  so  called  on  account  of  the  small  vesicular  ova  which  they  con- 
tain, are  the  representatives  of  the  testicles  in  the  male ;  the  product  secreted  by  both 
the  one  and  the  other  is  absolutely  indispensable  for  reproduction.  From  this  analogy 
between  the  ovaries  and  testes  the  ancients  called  them  testes  muliebres  (Galen). 

The  ovaries  (a  a,  fig.  188)  are  two  in  number,  and  are  situated  one  on  each  side  of  the 
uterus,  in  that  portion  of  the  broad  ligament  {d  d')  termed  the  posterior  ala  (J),  and  be- 
hind the  Fallopion  tube.  They  are  retained  in  this  position  by  the  broad  ligament,  and 
by  a  proper  ligament  called  the  ligament  of  the  ovary  (c). 

*  [One  of  these  sinuses  or  lacunae,  larger  than  the  rest,  and  situated  on  the  upper  surface  of  the  fossa  na- 
vicularis,  is  called  the  lacuna  magna  ;  they  appear  to  be  mucous  crypts.] 

t  [It  is  prolonged  into  the  ducts  of  Cowper's  glands  and  the  prostate,  into  the  vesiculiE  seminales,  vasa  def- 
erentia, and  tubuh  seminiferi,  and  through  the  ureters  into  the  uriniferous  ducts  ;  in  the  female  it  also  linei 
the  vagina,  uterus,  and  Fallopian  tubes ;  the  whole  forms  the  genito-urinary  system  of  mucous  membranes ;  it 
is  covered  throughout  with  an  epithelium,  which,  in  the  male  generative  apparatus,  approaches  the  columnar 
form.] 


462  SPLANCHNOLOGV. 

Then  situation  varies  at  different  ages,  and  also  according  to  the  state  of  the  uterus. 
In  the  foetus,  they  are  placed  in  the  lumbar  regions,  like  the  testicles.  During  pregnan- 
cy they  are  carried  up  into  the  abdomen  with  the  uterus,  upon  the  sides  of  which  they 
are  applied.  Immediately  after  delivery,  they  occupy  the  iliac  fossae,  where  they  some- 
times remain  during  the  whole  period  of  life,  being  retained  there  by  accidental  adhe- 
sions. It  is  extremely  common  to  find  them  thrown  backward,*  and  adhering  to  the  pos- 
terior surface  of  the  uterus. 

The  ovary  has  sometimes  been  found  in  inguinal  or  femoral  hernise :  by  descending 
into  the  labia  majora,  they  have  simulated  the  appearance  of  testicles. 

The  size  of  the  ovaries  varies  according  to  age,  and  according  as  the  uterus  is  gravid 
or  unimpregnated,  healthy  or  diseased.  They  are  relatively  larger  in  the  foetus  than  in 
the  adult ;  they  diminish  in  size  after  birth,  again  increase  at  the  period  of  puberty,  and 
become  atrophied  in  old  age.  During  the  latter  periods  of  pregnancy,  they  sometimes 
acquire  double  or  triple  their  ordinary  size. 

The  ovaries  are  of  an  oval  shape,  a  little  flattened  from  before  backward ;  they  are  of 
a  whitish  colour ;  their  surface  is  rough,  and,  as  it  were,  cracked,  and  is  often  covered 
with  very  dark-coloured  cicatrices,  which  have  been  incorrectly  regarded  as  remains  of 
ruptures  in  their  external  coat,  to  allow  of  the  escape  of  the  fecundated  ovum. 

The  ovary  is  free  in  front,  behind,  and  above,  but  is  attached  by  its  lower  border  to  the 
broad  hgament,  by  its  outer  end  to  the  trumpet-shaped  extremity  of  the  Fallopian  tube, 
and  by  its  inner  end  to  the  corresponding  side  of  the  uterus,  some  lines  below  the  upper 
angle  of  that  organ,  by  means  of  a  ligamentous  cord,  called  the  ligament  of  the  ovary  (c) ; 
which  was  for  a  long  time  regarded  as  a  canal  {ductus  ejaculans),  intended  to  convey  an 
ovarian  fluid  into  the  uterus.  The  tissue  of  this  ligament  strongly  resembles  that  of  the 
uterus,  and  seems  to  be  a  prolongation  from  it.  I 

Structure. — The  ovary  is  composed  externally  of  a  dense  fibrous  coat,  covered  by  the 
peritoneum,  which  adheres  so  closely  to  it  that  it  cannot  be  detached ;  and,  internally, 
of  a  spongy  and  vascular  tissue,  the  areolae  of  which  seem  to  be  formed  by  very  dehcate 
prolongations  from  the  external  coat ;  in  the  midst  of  this  tissue  (the  stroma,  from  arpufia, 
a  bed)  the  Graafian  vesicles  are  deposited.  These  vesicles  vary  in  number,  from  three  or 
four  to  fifty.  The  structure  of  the  ovary  is  most  evident  in  the  recently-delivered  fe- 
male. At  that  time  its  tissue,  expanded,  and,  as  it  were,  spongy,  appears  to  me  to  re- 
semble that  of  the  dartos,  and  is  traversed  by  a  great  number  of  vessels.  I  have  also 
seen,  in  recently-delivered  females,  the  ovaries  from  twelve  to  fifteen  times  larger  than 
usual,  and  converted  into  a  sac,  having  very  thin  parietes,  which  were  easily  torn  ;  the 
ovary  itself  was  of  a  spongy,  vascular,  and  diffluent  texture,  in  the  midst  of  which  the 
vesicles  were  seen  unaltered. 

The  vesicles  are  nothing  more  than  small  cysts  of  variable  size,  with  very  thin  trans- 
parent walls,  adhering  to  the  tissue  of  the  ovary,  and  containing  a  hmpid  serosity,  either 
colourless,  or  of  a  citron  yellow.  According  to  Von  Baer,  the  most  superficial  vesicles 
which  approach  the  expanded  extremity  of  the  Fallopian  tube,  contain  a  floating  body, 
which  was  imperfectly  seen  by  Malpighi,  and  constitutes  the  germ  or  ovum.  J 

I  have  often  metvdth  ovaries  destitute  of  vesicles ;  but  then  they  had  undergone  some 
change,  that  of  induration,  for  excunple.  May  the  absence  of  these  vesicles  be  regarded 
as  a  cause  of  sterility  1 

The  corpora  lutea,  according  to  the  observations  of  Haller,  consist  of  the  remains  of 
vesicles  that  have  been  ruptured  in  consequence  of  the  act  of  impregnation  ;  they  are 
brownish-yellow  masses,  of  a  tolerably  firm  consistence,  and  which  I  have  found  as  large 
as  a  cherry-stone  in  females  recently  delivered.  These  bodies  have  been  ascertained  to 
exist  in  females  who  have  never  borne  children,  and  this  anomaly  has  been  explained  by 
supposing  that  they  may  be  produced  in  consequence  of  masturbation.  We  would  re- 
mark, however,  that  there  is  no  constant  relation  between  the  existence  of  these  bodies 
and  the  occurrence  of  fecundation.  In  some  females  who  have  had  many  children,  no 
corpora  lutea  can  be  detected,  and,  on  the  other  hand,  a  corpus  luteum  has  been  found 
in  a  girl  of  five  years  of  age. 

The  bloodvessels  and  veins  of  the  ovary  correspond  exactly  with  those  of  the  testicles. 

*  The  situation  of  the  ovaries,  behind  the  Fallopian  tabes,  prevents  their  displacement  forward. 

t  It  has  even  been  stated  that  this  so-called  efferent  duct  of  the  ovary  divides  into  two  branches,  one  of 
which  opens  directly  into  the  uterus,  while  the  other  runs  along  its  border,  and  opens  near  the  os  uteri. 

t  [The  vesicles  of  De  Graaf  vary  from  the  size  of  a  pea  to  that  of  a  pin's  head  ;  they  have  two  tunics,  ono 
external  and  vascular,  the  other  called  the  ovi-capsule,  which,  according  to  Schwann,  is  lined  internally  with 
epithelium  (membrana  granulosa,  Bair).  In  each  vesicle  there  is  usually  but  one  ovum,  which  at  first  occu- 
pies its  centre,  but  in  the  mature  condition  approaches  the  inner  surface  of  its  internal  coat,  and,  sunounded 
by  a  granular  covering  (tunica  granulosa,  Barry),  is  held  there  by  retinacula  (Barry).  The  ovum  is  a  perfect- 
ly spherical  body,  of  uniform  size  (about  y^th  of  an  inch  in  diameter)  ;  it  consists  of  a  thick  but  very  trans- 
parent coat  (zona  pellucida,  Valentiri ;  chorion,  Wagrier),  which  surrounds  the  sul)stance  of  the  yolk  ;  within 
the  yolk  is  situated  the  germinal  vesicle  of  Purkinj6  (about  yg-jrth  of  an  inch  in  diameter),  and  within  that 
the  germinal  spot  of  Wagner  (about-g-^^th  or  g-rWth  of  an  inch).  The  changes  incidental  to  impregnation, 
according  to  Dr.  Barry,  commence  in  tlie  germinal  spot  and  vesicle.  For  farther  information,  and  for  a  list  of 
works  upon  this  subject,  see  Milller''s  Physiology,  translated  by  Dr  Baly,  and  Wagner's  Physitlogy,  trausla- 
tpd  by  Dr.  Willis.] 


THE   FALLOPIAN   TUBES. 


463 


Uses. — Without  precisely  determining  the  part  performed  by  the  ovaries  in  reproduc- 
tion, it  may  be  said  that  they  are  indispensable  to  that  function.  Extirpation  of  these 
bodies  is  followed  by  sterility.  And,  again,  ovarian  foetation  proves  that  fecundation 
may  occur  within  the  ovary.  The  use  of  the  Graafian  vesicles  in  generation  is  not  well 
known.* 

The  Fallopian  Tubes. 
The  tula  uterina  {ff,fig- 188)  are  two  ducts,  situated  in  the  substance  of  the  upper 
margin  of  the  broad  ...    ,„ 

Ugament.    They  are  t^-vsa. 

also  called  the  tubae 
rallopianae,+  the  Fal- 
lopian tubes,  after 
Fallopius,  who  first 
gave  a  good  descrip- 
tion of  them ;  they  ex- 
tend from  the  upper 
angle  of  the  uterus  to 
the  sides  of  the  cavity 
of  the  true  pelvis. 

Situation  and  Di- 
rection.— Floating,  as 
it  were,  in  the  cavity 
of  the  pelvis,  between 

the  ovaries  behind,  and  the  round  ligaments  (^  g)  in  front,  they  pass  transversely  out- 
ward, and  at  the  point  where  they  terminate,  bend  backward  and  inward,  in  order  to 
approach  the  outer  end  of  the  ovary,  to  which  they  are  attached  by  a  small  ligament. 
Each  Fallopian  tube  is  straight  in  the  inner  half  of  its  course,  but  describes  certain  wind- 
ings in  the  remaining  outer  portion,  which  are  so  considerable  in  certain  cases,  and 
especially  when  the  tube  has  been  the  seat  of  chronic  inilammation  or  of  dropsy,  as  to 
resemble  in  some  degree  the  windings  of  the  vas  deferens.  Moreover,  accidental  adhe- 
sions of  the  expanded  extremity  very  frequently  give  it  an  entirely  different  direction 
from  the  one  it  usually  takes.  The  tubes  may  be  drawn  down  with  the  ovaries  into  a 
hernial  sac,  as  I  have  several  times  observed. 

The  length  of  the  Fallopian  tube  is  four  or  five  inches,  but  it  sometimes  varies  on  the 
two  sides.  The  canal  in  their  interior  is  very  narrow  along  their  inner  half,  but  gradu- 
ally enlarges  as  it  proceeds  outward  to  their  termination,  which  is  expanded  and  divided 
into  irregular  fringes,  like  the  calyces  of  certain  flowers  ;  this  expanded  end  constitutes 
the  mouth  of  the  trumpet,  or  the  fimbriated  extremity  (e)  of  the  Fallopian  tube.  In  order 
to  obtain  a  good  view  of  this  structure,  it  is  necessary  to  place  the  tube  in  water,  and 
then  a  number  of  fringes  or  small  shreds  of  unequal  length  will  be  seen  floating  in  the 
liquid,  and  consisting  of  folds  divided  unequally,  and  sometimes  forming  two  or  three 
concentric  circles.  It  is  generally  said  that  one  of  these  fringes,  longer  than  the  rest,  is 
attached  to  the  outer  end  of  the  ovary ;  but  this  connexion  appears  to  me  to  be  effected 
by  means  of  a  small  ligament.  All  these  folded  fringes  terminate  around  a  circle  some- 
what narrower  than  the  adjoining  portion  of  the  tube ;  this  circle  constitutes  the  free 
orifi.ce,  or  ostium  abdominale  of  the  tube. 

The  outer  portion  of  the  tube  will  admit  the  end  of  a  moderate-sized  catheter,  while 
the  inner  portion  will  scarcely  admit  a  bristle.  The  diameter  of  that  portion  of  the  tube 
which  traverses  the  uterine  walls  is  capillary,  and  it  is  very  difficult  to  detect  with  the 
naked  eye  its  uterine  orifice,  or  ostium  uterinum  (o  o,  fig.  189).  As  the  canal  of  the  tube 
opens  into  the  uterine  cavity  on  the  one  hand,  and  into  the  cavity  of  the  peritoneum  on 
the  other,  it  forms  a  direct  communication  between  the  two ;  and  hence  certain  cases  of 
peritonitis  have  been  supposed  to  depend  upon  the  passage  of  a  fluid  from  the  uterus 
into  the  peritoneal  sac.  Not  very  unfrequently  the  fimbriated  orifice  of  the  tube  is  ob- 
literated ;  in  this  case  the  tube  becomes  dilated  like  a  cone,  having  its  base  directed  out- 
ward, and  it  also  becomes  much  more  flexuous. 

When  opened  longitudinally,  and  placed  under  water,  the  outer  or  wide  portion  of  the 
tube  presents  longitudinal  folds  of  unequal  breadth,  and  touching  by  their  free  edges. 

There  is  no  valve,  either  in  the  course  or  at  the  orifices  of  the  tube.  Its  narrow  jior- 
tion  is  hard  to  the  touch,  inextensible,  and  closely  resembles  in  appearance  the  vas  def- 
erens ;  its  wide  portion  is  collapsed,  and  its  walls  are  thin  and  extensible. 

Structure. — The  peritonium  adheres  closely  to  it,  and  forms  its  outer  coat ;  it  is  lined 
by  a  mucous  membrane,  which  can  be  easily  shown  in  the  whole  extent  of  the  broad  and 
folded  portion,  and  appears  to  form  of  itself  the  longitudinal  folds  already  described. 
This  lining  membrane  is  continuous,  on  the  one  hand,  with  the  uterine  mucous  mem- 
brane, and  on  the  other,  with  the  peritoneum,  at  the  fimbriated  extremity  of  the  tube ; 
it  thus  presents  the  only  example  in  the  human  body  of  the  direct  continuity  of  a  serous 

*  See  note,  p.  462.         t  [Literally,  the  Fallopian  tnimpeU,  from  their  expanded  abdominal  extremities.! 


464  SPLANCHNOLOGY. 

and  mucous  membrane.  Between  the  peritoneal  and  the  mucous  coats  is  found  a  proper 
membrane,  which  appears  to  be  a  prolongation  of  the  tissue  of  the  uterus,  and  is  proba- 
bly muscular.* 

Uses. — The  Fallopian  tubes,  which  represent  in  the  female  the  vasa  deferentia  in  the 
male,  serve  not  only  to  transmit  the  fecundating  principle  of  the  male,  but  also  to  con- 
duct the  fecundated  ovum  into  the  uterus.  These  uses  are  proved  by  the  sterility  of 
females  in  whom  the  tubes  have  been  tied  ;  and  by  the  occurrence  of  tubal  fcEtations,  in 
which  the  fecundated  ovum  is  arrested  in  the  cavity  of  the  tube,  and  thei'e  passes 
through  the  several  stages  of  development. 

The  fimbriated  extremity  of  the  tube  is  intended  to  embrace  the  ovary  during  the  act 
of  fecundation,  and  to  apply  itself  to  the  spot  from  which  the  ovxun  is  to  be  detached ;  it 
follows,  therefore,  that  any  adhesion  of  the  ovary  or  of  the  tube  which  prevents  this, 
acts  as  a  cause  of  sterility. 

The  Uterus. 

The  uterus  (uter,  a  leather-bottle),  matrix  (mater),  or  womb,  is  the  organ  of  gestation. 

It  is  situated  {u,fig.  190)  in  the  cavity  of  the  pelvis,  in  the  median  line,  between  the 
bladder  and  the  rectum,  and  is  retained  in  that  position  by  the  round  and  broad  ligament 
on  each  side,  and  by  the  upper  end  of  the  vagina  below. 

The  looseness  and  extensibility  of  its  connexions  enable  it  to  float,  as  it  were,  in  the 
cavity  of  the  pelvis,  and  to  be  moved  to  a  greater  or  less  extent.  The  facility  with 
which  it  can  be  drawn  towards  the  vulva  in  certain  surgical  operations,  and  its  displace- 
ment during  pregnancy,  when  it  rises  into  the  abdomen,  are  proofs  of  its  great  mobility. 

Direction. — Its  long  axis  is  directed  obliquely  downward  and  backward,  i.  e.,  it  coin- 
cides with  the  axis  of  the  brim  of  the  pelvis.  Its  direction  is  liable  to  frequent  varia- 
tions, the  history  of  which  belongs  to  midwifery ;  but  one  of  them,  viz.,  the  obliquity 
downward,  and  from  the  right  to  the  left  side,  is  so  frequent  that  it  has  been  regarded 
as  natural,  and,  according  to  some  anatomists,  appears  to  be  connected  with  the  posi- 
tion of  the  rectum  on  the  left  side  of  the  pelvis.  In  pregnancy,  this  inclination  is  almost 
constant,  and  has  some  relation  with  the  most  usual  position  of  the  child,  viz.,  that  in 
which  the  occiput  is  turned  towards  the  left  acetabulum  of  the  mother. 

Number. — The  uterus  is  single  in  the  human  species  ;  it  is  double  in  most  animals. 
The  cases  of  double  uterus  observed  in  the  human  subject  are  nothing  more  than  bifid 
uteri,  or  such  as  are  divided  by  a  septum  :  this  state  may  exist  either  in  the  body  of  the 
uterus  alone,  or  at  the  same  time  in  the  body  and  neck,  and  even  in  the  vagina. 

Size. — The  size  of  the  uterus  varies  according  to  age,  and  certain  physiological  con- 
ditions peculiar  to  this  organ.  It  is  very  small  until  puberty,  and  then  acquires  the  size 
which  it  subsequently  presents.  In  females  who  have  borne  children  it  never  returns 
to  its  original  size.  It  becomes  enormously  enlarged  during  pregnancy,  or  from  the  de- 
velopment of  certain  tumours.  In  old  age  it  becomes  atrophied,  and  is  sometimes  as 
small  as  it  is  in  newborn  infants.  The  following  are  the  measurements  of  the  uterus 
after  puberty :  length,  two  and  a  half  to  three  inches  ;  breadth,  at  the  fundus,  sixteen  to 
eighteen  lines,  at  the  neck  six  lines ;  antero-posterior  diameter,  or  thickness,  six  lines.t 

Weight. — The  weight  of  the  uterus  is  from  six  to  ten  drachms  at  puberty,  an  ounce 
and  a  half  or  two  ounces  in  females  who  have  had  children.  I  have  seen  it  from  one  to 
two  drachms  in  aged  females,  in  whom  it  had  become  atrophied.  At  the  end  of  preg- 
nancy the  weight  of  the  uterus  is  from  a  pound  and  a  half  to  three  pounds. 

Form. — The  uterus  is  shaped  like  a  small  gourd,  or  a  pear  flattened  from  before  back- 
ward. It  is  divided  into  a  body  (m),  and  cervix  or  neck  (A) ;  the  distinction  between  these 
two  parts  being  established  by  a  more  or  less  marked  constriction. 

Relations. — These  must  be  studied  in  front,  behind,  on  the  sides,  at  the  upper  border 
or  fundus,  and  at  the  lower  or  vaginal  extremity. 

The  anterior  surface  is  covered  by  the  peritoneum  in  its  upper  three  fourths,  and  is  in- 
directly in  relation  with  the  posterior  surface  of  the  bladder,  from  which  it  is  often  sep- 
arated by  some  convolutions  of  the  small  intestine ;  in  its  lower  fourth  it  is  in  imme- 
diate contact  with  the  inferior  fundus  of  the  bladder,  and  is  united  to  it  by  rather  loose 
cellular  tissue.  The  latter  relation  explains  why  cancerous  affections  of  the  uterus  so 
often  extend  to  the  base  of  the  bladder. 

The  posterior  surface  is  entirely  covered  by  the  peritoneum,  and  is  in  relation  with  the 
anterior  surface  of  the  rectum,  from  which  it  is  often  separated  by  some  convolutions 
of  the  small  intestine.  This  surface  is  much  more  convex  than  the  anterior ;  it  may  be 
examined  from  the  rectiun. 

Its  sides  are  slightly  concave,  and  give  attachment  to  the  broad  ligaments  (d  d',  d  d'), 
which  are  two  quadrilateral  folds  of  peritoneum,  extended  transversely  from  the  lateral 

*  [Muscular  fibres  have  not  yet  been  demonstrated  in  the  human  subject,  though  in  some  animals  circular 
and  longitudinal  contractile  fibres  have  been  found.  The  epithelium  of  the  mucous  membrane  is  columnar  and 
ciliated  :  by  the  action  of  the  cilia  the  contents  of  the  tubes  are  urged  towards  the  uterus :  Dr.  Heul6  has 
found  cilia  on  both  surfaces  of  the  fimbrise.] 

t  [The  body  of  the  uterus,  at  its  thickest  part,  viz.,  immediately  below  the  fundus,  is  from  eight  to  twelTe 
lines  thick.] 


THE   UTERUS.  465 

borders  of  the  uterus  to  the  sides  of  the  pelvis.  Their  upper  margin  is  divided  on  each 
side  into  three  folds  or  ridges,  formed  in  the  following  manner  :  a  posterior  fold  formed 
by  the  ovary  (a)  and  its  ligament  (c),  an  anterior  one  by  the  round  ligament  (g),  and  a 
middle  fold  by  the  Fallopian  tubes  (/).  Hence  some  anatomists  have  described  threr 
wings  {alee  vespertilionis)  in  each  of  the  broad  ligaments. 

The  broad  ligaments  may  be  regarded  as  forming  across  the  cavity  of  the  pelvis  a 
transverse  septum,  within  which  the  uterus  and  its  appendages  are  contained.  This 
septum  divides  the  cavity  into  two  portions  :  one  anterior,  containing  the  bladder,  the 
other  posterior,  in  which  are  situated  the  rectum,  and  almost  always  some  intestinal 
convolutions. 

Besides  the  broad  ligaments,  there  are  also  the  ligaments  of  the  ovary  and  the  round 
ligaments,  proceeding  from  the  sides  of  the  uterus. 

The  round  ligaments  {g  g)  have  a  fibrous  appearance,  but  are  evidently  continuous 
with  the  tissue  of  the  uterus.  They  arise  from  the  side  of  the  uterus,  below  and  in 
front  of  the  Fallopian  tubes,  pass  upward  and  outward  in  the  anterior  fold  of  the  broad 
ligament  to  the  abdominal  orifice  of  the  inguinal  canal,  into  which  they  enter,  being  ac- 
companied by  a  prolongation  of  the  peritoneum,  which  forms  around  them  a  cylindrical 
sheath  called  the  canal  of  Nuck.  In  females  far  advanced  in  life,  this  sheath  may  be 
traced  as  far  as  the  external  orifice  of  the  inguinal  canal. 

Besides  the  uterine  fibres  which  enter  into  its  composition,  the  round  ligament  also 
contains  a  great  number  of  veins,  which  may  become  varicose,  especially  near  the  ex- 
ternal orifice  of  the  inguinal  canal,  where  they  sometimes  simulate  a  hernia. 

The  upper  border  or  fundus  (i)  of  the  uterus  is  convex,  and  is  directed  upward  and  for- 
ward ;  it  is  covered  by  convolutions  of  the  small  intestine ;  when  not  distended,  it  never 
reaches  as  high  as  the  brim  of  the  pelvis,  and  cannot,  therefore,  be  felt  by  the  fingers  in 
the  hypogastric  region. 

The  lower  or  vaginal  extremity  of  the  uterus,  called  also  the  os  tincce,  from  its  shape,  is 
directed  downward  and  backward ;  it  is  embraced  by  the  vagina,  into  which  it  projects, 
and  is  divided  by  a  transverse  fissure  into  two  lips,  one  anterior,  the  other  posterior. 
The  OS  tinccR  is  small,  and  perforated  by  an  almost  circular  opening  {n)  in  females  who 
have  not  borne  children ;  but  in  those  who  have  been  mothers  it  forms  a  more  consid- 
erable projection,  and  its  fissure  is  more  marked  and  longer  transversely.*  In  some 
females  the  os  tinea;  is  of  considerable  length,  and,  as  it  were,  hypertrophied,  although 
the  uterus  is  healthy. 

The  anterior  lip  is  thicker  than  the  posterior,  which  is  a  little  longer  than  the  other. 
It  frequently  happens  that  in  old  females  every  trace  of  the  lips  of  the  os  tincae  disap- 
pears ;  the  orifice  alone  remains,  and  in  some  cases  even  that  is  obliterated.  In  such  a 
case  the  vagina  terminates  in  a  cul-de-sac,  at  the  bottom  of  which  a  round  and  yielding 
point  may  be  felt.  This  disappearance  of  the  two  lips  is  much  more  common  than  the 
elongation  of  the  neck  of  the  uterus,  which  was  pointed  out  by  my  venerable  colleague, 
M.  Lallemand. 

Cavity  of  the  Uterus. — The  cavity  of  the  uterus  is  extremely  smeill  in  comparison  with 
the  size  of  the  organ ;  its  figure  is  that  of  a  curvilinear  triangle ;  its  walls  are  in  con- 
tact, and  are  smooth,  and  covered  with  a  layer  of  mucus.  We  shall  examine  it  in  the 
body  and  neck  of  the  uterus. 

The  cavity  of  the  body  of  the  uterus  (w,  fig.  189)  is  of  a  triangular  form,  and  has  an 
opening  at  each  angle.  The  inferior  opening  {ostium  internum,  k)  Fig.  189. 
establishes  a  free  communication  between  the  cavities  of  the  body 
and  neck  ;  it  is  often  obliterated  in  old  women,  t  The  other  two 
orifices  (o  o)  are  those  of  the  Fallopian  tubes ;  they  are  scarcely 
visible  to  the  naked  eye,  and  are  situated  at  the  bottom  of  two 
fiuinel-shaped  cavities  formed  at  the  superior  angles  of  the  uterus, 
and  constituting  the  remains  of  the  division  of  the  body  of  the  ute- 
rus into  two  halves  or  comua.  This  division,  which  is  normal  in 
many  animals,  is  sometimes  met  with  in  the  human  female.  

Congenital  deficiency  of  the  cavity  of  the  uterus  is  very  rare.  My  colleague.  Profes- 
sor Rostan,  kindly  sent  me  a  specimen,  in  which  there  was  no  trace  of  a  cavity  in  the 
body  of  the  uterus,  although  the  cavity  of  the  neck  remained.  The  female  to  whom  it 
belonged  had  never  menstruated.     It  is  unnecessary  to  say  that  she  was  barren. 

The  cavity  of  the  neck  {h  to  n)  represents  a  cyUnder  flattened  from  before  backward, 
and  has  upon  its  anterior  and  posterior  walls  certain  ridges,  which  form  upon  each  wall 
along  the  whole  length  of  the  neck  a  tolerably  regular  median  column,  from  which  pro- 
ceed, at  more  or  less  acute  angles,  a  certain  number  of  smaller  columns,^  which  pro- 
ject to  a  greater  or  less  degree.     The  whole  appearance  resembles  that  of  a  fern-leaf, 

*  I  have  seen  the  os  tincse  lacerated  and  fissured  in  different  directions,  in  consequence  of  parturition. 

+  This  obliteration,  which  causes  retention  of  mucus  and  blood,  and,  consequently,  distension  and  ramol- 
lisa'inent  of  the  body  of  the  uterus,  is  so  common  that  M.  .Mayer  regards  it  as  normal. 

t  These  rugae,  which  vary  considerably  in  their  arrangement.  havfi-JlBfin  described  in  detail  by  Haller,  Bo- 
yer,  and  others.  v»^^-«^ 

N  N  N 


# 


466  SPLANCHNOLOGY. 

and  has  been  called  the  arbor  vita.  It  generally  disappears  after  the  tirst  latGtlr,  at  least 
only  traces  of  it  are  left.  Nevertheless,  it  is  not  unfrequently  found  perfect,  even  after 
several  accouchements — a  circumstance  of  some  importance  in  legal  medicine. 

The  internal  surface  of  the  body  of  the  uterus  is  much  more  vascular  than  the  neck. 
This  difference  is  particularly  observed  in  females  who  have  died  during  a  menstrual 
period,  in  whom  the  vessels  of  the  body  of  the  womb  are  much  developed,  and  that  or- 
gan itself  is  swollen  and  softened,  while  the  cervix  retains  its  accustomed  whiteness  and 
consistence. 

Another  character  of  the  uterine  cavity  is  the  existence  of  a  greater  or  less  number 
of  transparent  vesicles,  which  were  mistaken  by  Naboth  for  ova  {ova  of  Naboth),  but  are 
only  muciferous  follicles.  They  exist  both  in  the  body  and  neck  of  the  uterus,  but  are 
more  numerous  in  the  neck,  near  the  vaginal  orifice,  and  only  become  apparent  when 
the  mucus  accumulates  in  them  from  obliteration  of  their  orifices.  They  are  sometimes 
much  enlarged,  and  have  then  given  rise  to  the  opinion  that  some  more  serious  disease 
has  existed. 

The  orifices  of  the  uterine  sinuses,  described  by  the  older  anatomists  at  the  fundus  of 
the  uterus,  cannot  be  detected.  They  are  only  to  be  seen  after  delivery  in  the  situa- 
tion where  the  placenta  had  been  attached. 

The  parietes  of  the  unimpregnated  uterus  are  from  four  to  six  lines  in  thickness.  The 
thinnest  part  is  at  the  entrance  of  the  Fallopian  tubes,  where  they  are  not  more  than 
two  lines  thick.     The  parietes  of  the  cervix  are  thinner  than  those  of  the  body. 

Structure  of  the  Uterus. — The  constituent  parts  of  the  uterus  are,  a  proper  tissue,  an 
external  peritoneal  coat,  an  internal  mucous  membrane,  and  some  vessels  and  nerves. 

The  proper  tissue  is  of  a  grayish  colour,  very  dense  and  strong,  and  creaks  under  the 
knife  like  cartilage.  The  body  appears  less  consistent  than  the  neck,  but  this  depends 
upon  the  fact  of  its  being  more  frequently  the  seat  of  sanguineous  congestion.  It  is  com- 
posed of  fibres,  i.  e.,  it  has  a  linear  arrangement.  It  may  be  asked,  with  regard  to  the 
nature  of  these  fibres.  Do  they  consist  of  fibrous  tissue  1  are  they  muscular,  or  are  they 
analogous  to  tlie  yellow  tissue  of  the  arteries  1  The  following  considerations  will  de- 
termine this  question : 

The  walls  of  the  unimpregnated  uterus  appear  to  be  composed  of  a  fibrous  tissue,  trav- 
ersed by  a  great  number  of  vessels.  During  pregnancy,  or  in  consequence  of  the  devel- 
opment of  tumours,  or  the  accumulation  of  fluid  in  the  cavity  of  the  uterus,  its  proper 
tissue  acquires  all  the  properties  of  the  muscular  tissue,  as  it  exists  in  the  viscera  of 
organic  life,  and,  like  it,  is  endowed  with  contractility.  Can,  therefore,  the  presence 
of  a  foetus  or  a  foreign  body  in  the  uterus  cause  a  transformation  in  the  tissue  of  that 
organ  1*  Assuredly  not ;  but  the  great  influx  of  blood  into  the  uterus,  and  the  conse- 
quent distension  and  development  of  its  fibres,  reveals  a  structure  which  before  was  con- 
cealed by  the  state  of  condensation  and  atrophy  kept  up  by  inactivity. 

This  view  is  fully  confirmed  by  the  microscopical  observations  of  Rtederer,  and  the 
chemical  experiments  of  Schwilgue  ;  and  also  by  the  results  furnished  by  comparative 
anatomy,  which  has  shown  circular  and  longitudinal  muscular  fibres  in  the  uteri  of  some 
animals,  even  when  not  in  a  gravid  condition,  t 

The  nature  of  the  fibres  of  the  uterus  being  determined,  we  may  now  examine  their 
direction.  Some  anatomists  agree  with  Malpighi  and  Monro,  that  they  have  no  regu- 
larity in  their  disposition,  but  are  interlaced  in  an  inextricable  manner.  It  must  be  con- 
fessed that,  in  the  unimpregnated  uterus,  such  is  the  case ;  but  during  gestation,  the  ar- 
rangement of  the  greater  number  of  fibres  can  be  traced.  J 

In  the  body  the  external  thin  layer  is  composed  of  two  median  vertical  fasciculi,  one 
on  each  surface  of  the  uterus  ;  of  another  fasciculus  occupying  the  fundus,  and  of  some 
oblique  ascending  and  descending  fibres,  which  converge  towards  the  Fallopian  tubes, 
the  round  ligaments,  and  the  ligaments  of  the  ovaries,  which  contain  prolongations  of 
these  fibres.^  This  first,  or  superficial  layer,  belongs  exclusively  to  the  body  of  the  ute- 
rus. The  deep  layer  of  the  body  consists  of  two  series  of  circular  fibres  ;  each  series 
forming  a  cone,  the  apex  of  which  corresponds  to  the  Fallopian  tube,  while  the  base  is 
directed  towards  the  median  hne,  and  is  there  blended  with  that  of  the  opposite  side. 

The  neck  is  composed  entirely  of  circular  fibres,  which  intersect  each  other  at  very 
acute  angles. 

The  facts  furnished  by  comparative  anatomy  perfectly  accord  with  the  preceding  de- 
scription Thus,  in  the  uterus  of  a  sow,  which  had  httered,  I  found  that  the  cervix  was 
composed  exclusively  of  circular  fibres ;  and  that  the  cornua  (aduterum  of  M.  Geoffrey 

*  I  conceive  that  I  have  proved  by  facts,  that  only  three  tissues,  viz.,  the  muscular,  the  nervous,  and  the 
glandular,  are  never  the  products  of  organic  transformations. — (Vide  Essai  sur  VAnalomie  Pathol.,  1816.) 

t  CThe  muscular  fibres  of  the  gravid  uterus  have  been  described  by  Dr.  Baly  (translation  of  MUller's  Phys- 
iology). Like  other  inorganic  muscular  fibres,  they  have  no  transverse  striae  ;  they  arc  much  broader  than 
those  of  the  alimentary  canal,  and  taper  very  much  at  their  extremities,  which  are  sometimes  split  into  two 
or  three  points :  the  corpuscles  upon  them  are  comparatively  small.] 

X  Hunter,  Analomia  uteri.  Rosemberger  in  Schlegel,  ^yllog.  Oper.  Minor,  ad  Arlem  Obstetric.  Lipsis, 
\om.  ii.,  p.  290.     M6moire  pnisentt  i  1' Academic  de  M6decine,  par  Mmc.  Boivin.     Oct.,  1821. 

ft  I.  c,  in  the  i,'ravid  state. 


THE   UTERUS.  467 

St.  Hilaire),  which  represent  the  body  of  the  uterus  of  the  human  female,  were  formed 
by  two  layers  of  fibres,  one  external  and  longitudinal,  the  other  deep  and  circular.  From 
this  arrangement,  we  may  therefore  conclude  that  the  human  uterus  results  from  the  union 
of  two  comua,  which  communicate  directly  with  each  other,  instead  of  opening  separ- 
ately into  the  cavity  of  the  cervix. 

When  examined  in  the  state  of  pregnancy,  the  tissue  of  the  uterus  is  found  to  be  trav 
ersed  by  venous  canals,  or  uterine  sinuses,  which  are  of  very  considerable  size,  especial- 
ly opposite  the  attachment  of  the  placenta.  This  great  number  of  vessels  gives  to  the 
tissue  of  the  uterus  the  appearance  of  an  erectile  or  cavernous  structure,  having  muscu- 
lar parietes.* 

The  External  or  Peritoneal  Coat. — ^The  peritoneum,  after  covering  the  posterior  surface 
of  the  bladder,  is  reflected  upon  the  anterior  surface  of  the  uterus,  of  which  it  covers 
only  the  upper  three  fourths,  the  lower  fourth  being  in  immediate  contact  with  the  blad- 
der. At  the  fundus  of  the  uterus,  it  passes  to  the  posterior  surface,  which  it  covers  en- 
tirely, is  prolonged  a  short  distance  upon  the  vagina,  and  is  then  reflected  upon  the  rec- 
tum. The  broad  ligaments  are  formed  by  a  transverse  duplicature  of  this  coat.  Two 
falciform  folds,  formed  by  this  membrane  between  the  bladder  and  the  uterus,  are  called 
the  vesico-uterine  ligaments,  and  two  others,  between  the  uterus  and  the  rectum,  are  na- 
med the  recto-uterine  ligaments. 

The  peritoneum  adheres  very  loosely  to  the  borders  of  the  uterus,  but  much  more 
closely  as  it  approaches  the  median  line.  When  enlarged  during  pregnancy,  the  uterus 
becomes  covered  with  the  peritoneum  of  the  broad  ligament,  a  species  of  mesentery,  the 
folds  of  which  become  separated,  and  yield  to  the  increasing  size  of  the  organ. 

The  Internal  or  Mucous  Membrane. — The  existence  of  a  mucous  membrane  upon  the 
internal  surface  of  the  uterus  has  been  denied  by  those  anatomists  who  have  examined 
it  after  parturition,  especially  by  Morgagni  and  Chaussier,  and  so,  also,  by  those  who  do 
not  admit  the  presence  of  a  mucous  membrane  unless  it  can  be  demonstrated  over  a 
certain  space.  But  the  existence  of  a  mucous  membrane  on  the  internal  surface  of  the 
uterus  appears  to  me  incontestably  proved  by  the  following  considerations  : 

First,  every  organized  cavity  which  communicates  with  the  exterior  is  hned  by  a  mu- 
cous membrane ;  why,  therefore,  should  the  uterus  form  an  exception  to  this  rule  !  Sec 
ondly,  by  dissection  it  is  shown  that  the  mucous  membrane  of  the  vagina  is  continued 
into  the  neck  of  the  uterus,  and  then  into  the  body ;  but  in  this  latter  situation  it  is  des- 
titute of  epithelium.!  Notwithstanding  the  difficulty  of  dissecting  this  membrane,  on 
account  of  its  tenuity,  and  its  close  adhesion  to  the  tissue  of  the  uterus,  its  presence  is 
demonstrated  by  the  following  observations  :  Under  the  microscope,  the  internal  surface 
of  the  uterus  presents  a  papillary  appearance,  but  the  papillae  are  very  small ;  it  is  pro- 
vided with  follicles  or  crypts,  from  which  mucus  may  be  expressed  by  a  number  of 
points,  and  which  form  small  vesicles  w^jen  distended  with  mucus,  in  consequence  of 
obstruction  or  obliteration  of  their  orifices.  Thirdly,  it  is  extremely  vascular,  and  pre- 
sents a  capillary  network  of  the  same  appearance  as  that  of  the  other  mucous  mem- 
branes ;  and,  lastly,  it  is  constantly  lubricated  with  mucus.  Pathological  observations 
Eilso  show  that  the  internal  surface  of  the  uterus,  like  all  raucous  membranes,  is  liable  to 
spontaneous  hemorrhages  from  exh2dation,  without  breach  of  continuity,  to  catarrhic 
secretions,  and  to  those  growths  which  are  denominated  mucous,  vesicular,  and  fibrous 
polypi :  and  it  is  generally  admitted  that,  where  there  is  an  identity  of  disease,  there  is 
also  identity  of  structure. 

During  pregnancy,  the  elements  of  the  mucous  membrane  are  separated;  the  vessels 
become  penicillate,  and  greatly  increased  in  size ;  but  in  proportion  as  the  uterus  returns 
to  its  original  dimensions,  the  mucous  membrane  regains  its  primitive  form,  and  its  dis- 
sociated elements  approach  each  other.  It  seems  as  if  this  membrane  was  destroyed 
by  a  true  exfoliation,  and  then  entirely  reproduced. 

The  arteries  of  the  uterus  are  derived  from  two  sources  :  the  principal,  called  the  ute- 
rine, arise  from  the  hypogastric ;  the  others  proceed  from  the  spermatic  or  ovarian  ar- 
teries to  the  borders  of  the  uterus,  and  are  distributed  upon  it :  both  sets  are  very  tor- 
tuous. 

The  veins  are  remarkable  for  their  enormous  size  during  pregnancy  and  after  parturi- 
tion. The  term  uterine  sinuses  has  been  given  to  the  large  veins  which  are  then  found 
in  the  substance  of  the  organ ;  and  this  term  is  not  altogether  without  foundation,  for 
these  venous  canals  are  formed  by  the  lining  membrane  of  the  veins  which  adheres  to 
the  proper  tissue  of  the  uterus,  just  as,  in  the  sinuses  of  the  dura  mater,  it  adheres  to 
the  fibrous  tissue  of  that  membrane. 

The  lymphatics,  which  have  been  well  examined  only  during  pregnancy  and  after  par- 

*  This  combination  of  the  erectile  and  muscular  tissues  is  found  in  the  penis  of  the  horse,  and  perhaps, 
also,  in  that  of  man. 

t  [The  mucous  membrane  of  the  uterus  contains  numerous  tubular  glands,  or  crypts,  resembling,  in  form 
and  direction,  the  tubuli  of  the  stomach,  and  the  crypts  of  Lieberkuehn,  found  in  the  intestinal  canal.  The 
epithelium  of  this  mucous  membrane  is,  according  to  Henl6,  columnar,  and  also  ciliated  from  the  fundus  to 
the  middle  of  the  cervix  uteri ;  below  that  point  it  passes  into  the  squamous  form  of  epithelium  found  in  the 
ragina  and  on  the  labia.] 


4§8  SPLANCHNOLOGY. 

turition,  at  which  time  I  have  often  seen  them  full  of  pus,  are,  like  the  veins,  extremely 
large  (see  Anat.  Path.,  avec  planches,  liv.  xiv.) ;  they  form  several  layers  in  the  sub- 
stance of  the  uterus,  ^^e  most  superficial  of  which  is  the  most  developed.  They  termi- 
nate in  the  pelvic  and  lumbar  lymphatic  glands  ;  some  accompany  the  ovarian  veins. 

The  nerves,  as  seen  in  the  pregnant  condition,  have  been  well  described  and  figured  by 
Tiedemann.  Some  of  them  are  derived  from  the  renal  plexus,  and  surround  the  ovarian 
arteries  ;  others  proceed  from  the  hypogastric  plexus,  and  are  formed  by  some  of  the 
anterior  branches  of  the  sacral  nerves,  and  by  branches  from  the  lumbar  ganglia  of  the 
sympathetic. 

Development. — It  is  generally  agreed  that  the  body  of  the  uterus  is  always  bifid,  or  two- 
horned,  in  the  embryo,  up  to  the  end  of  the  third  month  ;  and  that,  towards  the  end  of 
the  fourth  month,  the  two  halves  are  united  to  form  a  single  cavity.  I  have  not  observed 
tliis  in  the  earliest  periods  of  intra-uterine  life. 

During  fcetal  life,  the  uterus,  instead  of  presenting  the  same  form  as  it  subsequently 
possesses,  is  decidedly  larger  at  the  neck  than  in  the  body :  at  this  period  the  broadest 
part  of  the  uterus  is  its  vaginal  extremity. 

After  birth,  and  up  to  the  time  of  puberty,  the  development  of  the  uterus  is  almost 
stationary  ;  so  that,  according  to  the  observations  of  Roederer,  which  are  confirmed  by 
Professor  Duges,  it  is  from  twelve  to  fourteen  lines  long  in  the  new-born  infant,  and  only 
an  inch  and  a  half  at  ten  years  of  age. 

At  puberty,  the  uterus  rapidly  acquires  its  full  dimensions,  and  at  the  same  time  be- 
comes the  seat  of  a  periodic  and  sanguineous  exhalation,  the  occurrence  of  which  con- 
stitutes menstruation. 

In  old  age,  the  uterus  becomes  atrophied,  and  altered  in  shape  ;  the  cervix  and  body 
are  separated  by  a  much  more  decided  constriction.  These  two  parts  of  the  uterus 
seem  to  become  more  independent  of  each  other.  The  lips  of  the  os  tincae  are  general- 
ly effaced  in  old  women.  The  tissue  of  the  body  preserves  its  softness,  while  that  of 
the  neck  acquires  an  extreme  density. 

The  situation  of  the  uterus  is  very  different  at  different  ages.  In  the  foetus  it  projects 
beyond  the  brim  of  the  pelvis,  and  is  in  the  abdominal  cavity ;  after  birth,  and  in  conse.- 
quence  of  the  development  of  the  pelvis,  it  seems  gradually  to  sink  into  that  cavity.  At 
the  age  of  ten  years,  the  fundus  of  the  uterus  is  on  a  level  with  the  brim  ;  afterward  it 
is  lower  down.  In  old  women  it  is  generally  inclined  to  one  side,  or  reversed  upon  the, 
rectum. 

Functions. — The  uterus  is  the  organ  of  gestation  ;  the  fecundated  ovum  is  deposited 
in  its  cavity,  and  there  meets  with  the  most  favourable  conditions  for  its  development. 
The  uterus  is  also  the  principal  agent  in  the  expulsion  of  the  foetus. 

The  Vagina. 

The  vagina  is  a  membranous  canal,  extending  from  the  vulva  to  the  uterus  ;  it  is  the 
female  organ  of  copulation,  and  also  forms  the  passage  for  the  menstrual  blood,  and  the 
product  of  conception. 

It  is  situated  in  the  cavity  of  the  pelvis  between  the  bladder  and  the  rectum,  and  is 
held  in  that  situation  by  tolerably  close  adhesions  to  the  neighbouring  parts,  but  still  is 
so  loose  that  it  can  be  everted  like  the  finger  of  a  glove. 

Direction. — It  is  directed  obliquely  forward  and  downward,  i.  e.,  it  coincides  with  the 
axis  of  the  outlet  of  the  pelvis ;  and  as  the  direction  of  the  uterus  corresponds  with  the 
axis  of  the  brim,  these  two  parts  form  an  angle  or  curvature  with  each  other,  having  its 
concavity  directed  forward. 

Shape  and  Dimensions. — The  vagina  is  shaped  like  a  cylinder,  flattened  from  before 
backward,  and  having  its  walls  in  contact,  as  may  be  seen  upon  applying  the  speculum. 
It  is  from  four  to  five  inches  long  ;*  sometimes  it  is  much  shorter :  I  have  seen  it  as 
short  as  an  inch  and  a  half  This  congenital  shortness  must  be  distinguished  from  the 
apparent  shortness  produced  by  prolapsus  uteri. 

The  vagina  is  not  of  the  same  diameter  throughout.  Its  lower  orifice  is  the  narrow- 
est part,  while  its  upper  extremity  is  the  widest.  In  females  who  have  borne  children, 
the  bottom  of  the  vagina  forms  a  large  ampulla,  in  which  the  speculum  may  be  moved 
about  extensively,  and  in  Avhich,  also,  a  considerable  quantity  of  blood  may  accumulate 
during  hemorrhage.  It  is,  moreover,  a  dilatable  canal,  as  is  proved  during  parturition  ; 
and  is,  at  the  same  time,  elastic,  and  contracts  after  delivery,  so  as  almost  to  return  to 
its  original  dimensions.    It  would  appear,  also,  to  be  capable  of  a  vermicular  contraction. 

Relations. — In  front,  where  it  is  slightly  concave,  it  corresponds  to  the  inferior  fundus 
of  the  bladder,  to  which  it  is  united  by  very  dense  filamentous  cellular  tissue,  resembling 
the  dartos  ;  it  cannot  be  separated  from  the  urethra,  which  appears  to  be  hollowed  out 
of  the  substance  of  its  walls.  The  close  adhesion  of  the  vagina  to  the  bladder  and  ure- 
tlua  accounts  for  these  latter  organs  always  following  the  uterus  in  its  displacements. 
Behind,  the  vagina  corresponds  with  the  rectum,  through  the  medium  of  the  peritoneum 
in  its  upper  fourth,  and  immediately  in  its  lower  three  fourths.     It  adheres  to  the  rec- 

*  LFrom  the  nature  of  the  cune  formed  by  the  vagina,  its  anterior  wall  is  shorter  than  the  posterior.] 


THE    VAGINA.  4^ 

turn  by  cellular  tissue  resembling  the  dartos,  and  analogous  to  that  existing  between  it 
and  the  bladder,  but  much  looser,  so  that  the  rectum  does  not  follow  the  vagina  in  its 
displacement.  The  sides  of  the  vagina  give  attachment  to  the  broad  ligaments  above, 
and  to  the  superior  pelvic  fascia  and  the  levatores  ani  below,  and  they  are  in  relation 
with  the  cellular  tissue  of  the  pelvis  and  with  some  venous  plexuses. 

Internal  Surface. — The  internal  surface  of  the  vagina  is  covered  with  an  epithelium, 
which  can  be  very  easily  demonstrated,  and  which  is  prolonged  as  far  as  the  os  uteri, 
where  it  terminates  by  a  sort  of  indented  margin,  in  the  same  manner  as  the  epithelium 
of  the  oesophagus  ceases  at  the  stomach.*  This  surface  presents  on  both  walls,  but  es- 
pecially in  front  and  near  the  orifice  of  the  vulva,  some  transverse  rugae,  or,  rather, 
prominences,  which  very  nearly  resemble  the  irregular  ridges  upon  the  palate ;  they  all 
pass  from  a  median  prominent  line,  which  is  often  prolonged  like  a  median  raphd  along 
the  whole  anterior  wall  of  the  vagina ;  the  raphe  on  the  posterior  wall  is  not  so  well 
marked.  These  two  median  raphes  are  called  the  columns  of  the  vagina.  They  are 
the  remains  of  the  median  septum,  which  generally  coexists  with  a  bifid  uterus,  but  ex- 
ists sometimes  independently  of  it. 

The  transverse  rugae  of  the  vagina  are  very  numerous  in  the  new-bora  infant  and  in 
virgins  ;  they  are  partially  effaced  after  the  first  labour,  at  the  upper  part  of  the  vagina, 
but  always  remain  at  the  lower  part.  These  rugae  are  not  folds,  and  do  not  appear  to 
assist  in  the  enlargement  of  the  vagina. 

The  upper  extremity  of  the  vagina  embraces  the  neck  of  the  uterus,  upon  which  it  is 
prolonged  without  any  line  of  demarcation,  and  forms  a  circular  trench  around  the  os 
tincae,  which  is  deeper  behind  than  in  front. 

The  lower  extremity,  or  opening  into  the  vulva,  presents  a  corrugated  transverse  pro- 
jection in  front,  which  is  exposed  by  separating  the  labia  and  nymphae  ;  it  narrows,  and 
seems  even  to  close  the  entrance  of  the  vagina. 

In  virgins,  the  orifice  of  the  vulva  is  provided  with  a  membrane,  concerning  the  form 
and  existence  of  which  there  have  been  numerous  disputes  ;  it  is  called  the  hymen,  and 
is  a  sort  of  diaphragm  interposed  between  the  internal  genitals  on  the  one  hand,  and  the 
external  genitals  and  urinary  passages  on  the  other.  This  membrane  is  of  a  crescentic 
shape,  having  its  concavity  directed  forward,  and  closing  up  the  posterior  and  lateral 
parts  of  the  vagina:  it  sometimes  forms  a  complete  circle,  perforated  in  the  centre.  Its 
free  margin  is  fringed  ;  it  varies  in  breadth  in  different  individuals,  and  thus  regulates 
the  dimensions  of  the  vaginal  orifice.  The  hymen  sometimes  forms  a  complete  mem- 
brane, constituting  what  is  called  imperforate  vagina. 

The  hymen  is  composed  of  a  duplicature  of  mucous  membrane,  varying  in  strength, 
and  containing  within  it  some  cellular  tissue  and  vessels.  The  debris  remaining  after 
its  laceration  constitute  the  carunculce  myrtiformes,  which  vary  in  number  from  two  to  five. 

Structure. — The  walls  of  the  vagina  consist  of  an  erectile  spongy  tissue  interposed  be- 
tween two  very  strong  fibrous  layers,  of  which  the  external  is  the  thicker.  Around  this 
erectile  tissue  we  find  a  tolerably  thick  layer  resembling  the  tissue  of  the  dartos  con- 
densed. I  cannot  agree  with  sonie  anatomists  in  admitting  an  identity  of  structure  in 
the  walls  of  the  vagina  and  uterus,  for  in  no  case  does  the  vagina  assume  a  muscular 
character  hke  the  latter  organ.  From  the  presence  of  the  dartoid  tissue  an  obscure  ver- 
micular movement  may  take  place,  and  assist  the  elasticity  of  the  walls  of  the  vagina. 

The  posterior  wall  and  the  upper  part  of  the  anterior  wall  are  thin ;  the  vagina  is  veiy 
much  thicker  opposite  the  urethra,  which  seems  to  be  hollowed  out  of  its  substance,  and 
terminates  by  a  rugous  enlargement,  which  forms,  at  the  entrance  of  the  vagina,  the  pto- 
jection  already  mentioned,  and  which  is  only  a  very  dense  spongy  tissue. 

The  mucous  membrane  of  the  vagina  is  remarkable  for  the  thickness  of  its  epitheli- 
um,t  for  its  close  adhesion  to  the  proper  membrane,  and  for  its  highly  developed  papillae, 
especially  at  the  entrance  of  the  passage,  where  the  rugae  are  nothing  more  than  papillae 
in  an  exaggerated  form.     The  mucous  follicles  can  be  easily  demonstrated. 

The  Bulb  of  the  Vagina. — Besides  the  spongy  expansion  at  the  orifice  of  the  vagina, 
there  is  in  front  and  on  each  side  of  this  orifice  an  enlargement  or  cavernous  body,  occu- 
pying the  interval  between  the  entrance  of  the  vagina  and  the  roots  of  the  clitoris.  It 
is  not  very  thick  in  the  middle,  where  it  is  placed  between  the  meatus  urinarius  and  the 
union  of  the  roots  of  the  clitoris,  but  gradually  enlarges  from  this  point,  and  terminates 
below,  upon  each  side  of  the  vagina,  by  an  enlarged  extremity.  The  posterior  wall  of 
the  vagina  is  the  only  part  in  which  it  does  not  exist.  In  position,  as  well  as  shape,  it 
resembles  the  bulb  of  the  urethra  in  the  male.  J 

The  Constrictor  Vagina. — ^This  consists  of  two  muscles,  one  on  each  side  of  the  ori- 
fice of  the  vagina,  the  arrangement  of  which  very  nearly  resembles  that  of  the  bulbo- 

*  tin  both  of  these  situations  the  epithelium  does  not  cease,  but  is  merely  changed  in  its  character  (see 
note,  p.  467).] 

t  [The  epithelium  in  the  vagina,  and  also  in  the  vulva,  is  squamous.] 

t  In  one  subject,  on  the  outer  side  of  this  vaginal  bulb,  I  found  a  smooth  sero-fibrous  pouch,  containing'  a 
transparent  mucous  fluid.  A  narrow  canal,  proceeding  from  this  pouch,  passed  directly  towards  the  entrance 
of  the  vagina.  I  could  not  find  the  orifice  of  this  caual,  which  was  probably  obliterated.  The  same  dispoai- 
tion  existed  on  both  sides. 


470  SPLANCHNOLOGY. 

cavernosus  in  the  male.  Each  muscle  commences  in  front  of  the  rectum,  by  an  inter- 
lacement of  fibres  common  to  it,  to  its  fellow  of  the  opposite  side,  and  to  the  sphincter 
ani,  passes  forward  under  the  fonxi  of  a  flattened  band,  and  terminates  upon  the  sides 
of  the  clitoris,  a  portion  being  continued  above  it,  and  blended  with  the  suspensory  liga- 
ment of  that  body. 

Relations. — It  is  covered  on  the  outside  by  the  skin  and  the  fatty  cellular  tissue  of  the 
labia  majora ;  it  corresponds  on  the  inside  with  the  bulb  of  the  vagina,  which  it  must 
strongly  compress. 

The  proper  vaginal  arteries  arise  from  the  hypogastric.  The  uterine  arteries  also 
send  numerous  branches  to  the  vagina. 

The  veiiis  are  very  niunerous,  form  plexuses,  and  terminate  in  the  hypogastric  veins. 

The  turves  are  derived  from  the  hypogastric  plexus. 

Development. — The  rugae  of  the  vagina  are  not  visible  until  about  the  end  of  the  fifth 
month  of  intra-uterine  life  ;  from  the  sixth  to  the  eighth  they  become  much  more  devel- 
oped than  they  are  subsequently.  The  transverse  rugae  are  visible  in  the  whole  length 
of  the  vagina,  and  are  placed  closely  to  each  other.  The  hymen  does  not  make  its  ap- 
pearance until  about  the  middle  of  fcetal  life ;  it  is  directed  forward,  and  is  rough  and 
jagged.    It  is  always  present. 

The  Urethra  in.  the  Female. 

This  canal,  which  is,  as  it  were,  hollowed  out  of  the  anterior  wall  of  the  vagina,  dif- 
fers considerably  from  the  male  urethra,  of  which  it  represents  the  membranous  portion 
only.     It  is  about  one  inch  in  length. 

It  is  very  difficult  to  determine  its  diameter,  on  account  of  its  dilatability  ;  but  it  is 
about  three  or  four  lines  when  quite  undilated.     Its  lower  end  is  somewhat  contracted. 

It  is  directed  obliquely  downward  and  forward,  and  is  slightly  concave  in  front. 

Relations. — Anteriorly,  while  behind  the  symphysis,  it  is  in  contact  with  the  cellular' 
tissue  of  the  pelvis ;  opposite  the  symphysis,  it  is  in  relation  with  the  angle  of  union  of 
the  two  crura  of  the  clitoris.  The  pelvic  fascia,  or,  rather,  the  anterior  ligaments  of  the 
bladder,  form  a  half  sheath  for  it  above,  but  are  separated  from  it  by  numerous  venous 
plexuses.  Posteriorly,  the  canal  is  so  closely  united  to  the  vagina,  that  it  is  impossible 
to  separate  them. 

The  vesical  orifice  of  the  female  urethra  is  similar  to  that  of  the  male,  only  there  is  no 
prostate  gland. 

The  internal  surface  is  of  a  deep  colour,  and  is  remarkable  for  certain  longitudinal  folds 
or  parallel  ridges,  the  majority  of  which  are  not  effaced  by  distension  ;  one  of  these  folds 
is  in  the  median  line  of  the  lower  wall  of  the  canal.  We  also  find  the  orifices  of  mucous 
crypts  or  lacunae,  and  some  parallel  longitudinal  veins. 

Structure. — It  is  muscular  and  erectile,  like  the  membranous  portion  of  the  male  ure- 
thra. It  is  surrounded  by  a  thick  layer  of  circular  muscular  fibres,  which  seem  to  be 
continuous  with  the  fibres  of  the  bladder,  some  of  the  longitudinal  fibres  of  that  organ 
being  prolonged  upon  the  outside  of  these.*  A  thin  layer  of  spongy  or  erectile  tissue  lies 
subjacent  to  the  mucous  membrane,  which  is  very  thin. 

The  Vulva. 

Under  the  term  vulva  we  include  all  the  external  genitals  of  the  female,  viz.,  the  mons 
Veneris,  the  labia  majora  and  minora,  the  clitoris,  and  the  meatus  urinarius,  to  which 
we  may  add  the  orifice  of  the  vagina  already  described. 

The  mons  Veneris  is  a  rounded  eminence,  more  or  less  prominent  in  different  individ- 
uals, situated  in  front  of  the  pubes,  and  surmounting  the  vulva ;  the  prominence  of  this 
part  is  owing  partly  to  the  bones,  and  partly  to  a  collection  of  fatty  tissue  beneath  the 
skin ;  it  is  covered  with  hair  at  the  time  of  puberty. 

The  labia  majora  are  two  prominent  cutaneous  folds,  which  form  the  limits  of  an  an- 
tero-posterior  opening,  by  most  anatomists  named  the  vulva.  They  are  flattened  trans- 
versely, and  are  thicker  in  front  than  behind ;  their  external  surfaces  are  covered  with 
hairs ;  their  internal  surfaces  are  moist  and  smooth,  and  in  contact  with  each  other ; 
their  free  borders  are  convex,  and  provided  with  hair ;  their  anterior  extremities  are  con- 
tinuous with  the  mons  Veneris ;  their  posterior  extremities  unite  to  form  a  commissure 
called  the  fourchette,  which  is  almost  always  lacerated  in  the  first  labour.  The  interval 
between  the  fourchette  and  the  anus  constitutes  the  perineum,  which  is  generally  from 

*  [The  female  urethra  perforates  the  triangular  ligament  precisely  in  the  same  way  as  the  membranous  por- 
tion of  the  urethra  in  the  male  ;  and,  moreover,  between  the  two  layers  of  the  ligament  it  is  surrounded  by  mus- 
cular fibres  corresponding  exactly  with  the  compressor  urethra  in  the  male  sex.  The  vertical  fibres,  or  Wil- 
son's muscles,  were  noticed  by  him  (loc.  cit.),  descending  from  the  symphysis,  separating  on  the  urethra,  and 
passing  around  it ;  the  transverse  fasciculi,  which  are  often  very  large,  form  together  the  depressor  urethra  Of 
Santorini,  and  were  described  and  figured  by  that  author  (Obs.  Anat.)  as  arising  by  a  broad  tendou  from  the 
lower  part  of  the  rami  of  the  pubes,  above  the  erectores  clitoridis,  passing  obliquely  upward  and  inward,  and 
uniting  with  each  other  dijove  the  urethra.  Mr.  Guthrie  has  shown  {loc.  cit.)  that  the  relations  of  the  verti- 
cal and  transverse  fasciculi  to  each  other,  to  the  urethra,  and  to  the  layers  of  the  Uiaugular  ligament,  are  pre- 
cisely the  same  as  in  the  male.]  '  .,-j4J-i 


THE  VULVA.  471 

eight  to  ten  lines  long.  The  interval  between  the  fonrchette  and  the  entrance  of  the 
vagina  is  called  the  fossa  navicularis. 

The  constituent  parts  of  the  labia  majora  are,  a  cutaneous  layer,  a  mucous  layer,  both 
provided  with  numerous  sebaceous  follicles.*  In  fat  persons,  a  great  quantity  of  adipose 
tissue,  a  layer  of  dartoid  tissue  next  the  mucous  membrane,  and  some  arteries,  veins, 
lymphatics,  and  nerves.  They  are  therefore  very  analogous  to  the  scrotum  in  the  male, 
and,  Uke  it,  are  liable  to  serous  infiltration  in  anasarca. 

The  labia  minora,  or  nymphcB,  are  seen  after  separating  the  labia  majora,  under  the 
form  of  two  layers  of  mucous  membrane  ;  they  are  narrow  behind,  where  they  commence 
upon  the  inner  surface  of  the  labia  majora,  and  they  enlarge  gradually  as  they  converge 
towards  each  other  in  front.  At  the  chtoris  they  become  slightly  contracted,  and  bifur- 
cate before  their  termination.  The  lower  division  of  the  bifiircation  is  attached  to  and 
continuous  with  the  glans  of  the  clitoris  ;  the  upper  division  unites  with  that  of  the  op- 
posite side,  and  forms  a  hood-like  fold  above  that  body,  called  the  preputium  clitoridis. 

Tlie  nymphae  are  provided  with  very  large  crypts,  wliich  are  visible  to  the  naked  eye, 
and  secrete  an  abundance  of  sebaceous  matter.  They  vary  much  in  size,  according  to 
age  :  thus,  in  new-bom  infants,  they  project  beyond  the  labia  majora,  principally  on  ac- 
count of  the  imperfect  development  of  the  latter.  They  also  vary  in  different  individ- 
ujds :  in  some  females  being  extremely  small,  and  in  others  always  projecting  beyond 
the  labia  majora ;  and,  lastly,  in  different  countries  ;  for  in  certain  African  nations,  among 
the  Hottentots,  for  example,  they  are  of  a  disproportionate  length,  and  constitute  what 
is  called  in  females  of  that  race  the  apron. 

The  clitoris  is  an  erectile  apparatus,  forming  a  miniature  representation  of  the  corpus 
cavernosum  of  the  penis.  Its  free  extremity  is  seen  in  the  anterior  part  of  the  vulva, 
about  six  lines  behind  the  anterior  commissure  of  the  labia  majora,  and  resembles  a  tu- 
bercle situated  in  the  median  line,  covered,  as  by  a  hood,  with  the  upper  divisions  of  the 
bifurcated  nymphae,  and  continuous  with  the  lower  divisions  of  the  same.  This  tuber- 
cle, which,  though  imperforate,  has  been  compared  to  the  glans  penis  {glans  clitoridis),  is 
generally  very  small.  Sometimes,  however,  it  is  very  long,  so  as  to  have  excited  a  sus- 
picion of  the  existence  of  hermaphrodism.  In  one  instance  that  came  under  my  obser- 
vation, the  free  part  of  the  clitoris  was  two  inches  long,  and  extremely  slender. 

Like  the  corpus  cavernosum  in  the  male,  the  clitoris  arises  from  the  ascending  rami 
of  the  ischia  by  two  roots,  which  expand  and  converge  until  they  arrive  opposite  the 
symphysis,  where  they  unite  and  form  a  single  corpus  cavernosum,  flattened  on  each 
side ;  this,  after  passing  for  some  lines  in  front  of  the  symphysis,  separates  from  it,  and 
forming  a  curve  with  the  convexity  directed  forward  and  upward,  and  the  concavity 
downward  and  backward,  gradually  becomes  smaller  towards  its  free  extremity. 

It  has  a  suspensory  ligament  precisely  resembling  that  of  the  penis,  and  ischio-cavei- 
nosi  muscles,  similar  to,  but  smaller  than  those  of  the  male.  We  have  already  said  that 
the  constrictor  vaginae,  which  represents  the  bulbo-cavemosi  of  the  penis,  has  a  similar 
arrangement  to  those  muscles,  t.  c,  it  passes  upon  the  sides  of  the  clitoris,  and  then  be- 
comes continued  on  to  its  suspensory  ligament. 

The  last  circumstance  which  completes  the  analogy  between  the  clitoris  and  the  corpus 
cavernosum  of  the  penis,  is  the  reception  of  the  canal  of  the  urethra  into  the  V-shaped 
interval  formed  by  the  union  of  the  two  crura  of  the  clitoris. 

The  corpus  cavernosum  of  the  clitoris  forms  a  longitudinal  ridge  between  the  labia  ma- 
jora, extending  from  the  anterior  commissure  to  the  glans  of  the  clitoris. 

The  Meatus  Urinarius. — About  an  inch  below  and  behind  the  clitoris,  we  find  in  the 
median  line,  immediately  above  the  projecting  margin  of  the  opening  of  the  vagina,  tfce 
meatus  urinarius,  or  the  orifice  of  the  urethra,  which  constantly  appears  closed. 

The  Mucous  Membrane  of  the  Vulva. — The  mucous  membrane  lining  the  vulva  is  con- 
tinuous, on  the  one  hand,  with  the  skin  at  the  intemad  surface  of  the  labia  majora,  and 
with  the  mucous  membrane  of  the  vagina  on  the  other ;  upon  the  labia  majora  and  nym- 
phae it  has  a  great  number  of  sebaceous  follicles  visible  to  the  naked  eye,  and  yielding  a 
cheesy,  odorous  secretion  ;  and  also  mucous  follicles,  which  are  most  numerous  near  the 
meatus  urinarius,  and  open  into  culs-de-sac,  the  orifices  of  which  are  visible  to  the  na- 
ked eye,  and  are  often  large  enough  to  admit  the  blunt  extremity  of  a  probe. 

Development. — In  the  foetus  the  labia  majora  are  small,  and  separated  from  each  other 
by  the  nymphae,  which  are  much  larger  in  proportion,  and  also  by  the  clitoris,  which  pro- 
jects beyond  them  to  a  greater  extent  in  the  earlier  periods  of  development.  This  pre- 
dominance of  the  clitoris  is  still  so  decided  at  birth,  that  it  has  occasioned  mistakes  con- 
cerning the  sex  of  the  infant. 


THE  MAMM^. 
Number. — Situation. — Size. — Form. — Structure. — Development. 
The  mavima  or  breasts  (jiadrbg,  from  fidu,  to  seek  eagerly,  because  the  infant  seeks^ 

*  It  is  not  rare  to  see  small  and  very  short  hairs  growing  from  the  sebaceous  follicles  on  the  inner  surface 
of  the  labia  majora  ;  they  are  analogous  to  '.hose  of  the  carunculse  lachrymales. 


472  SPLANCHNOLOGY. 

them  for  the  milk)  are  glandular  appendages  of  the  generative  system,  which  secrete 
the  milk,  and  even  after  birth  establish  intimate  relations  betvireen  the  mother  and  the 
infant. 

The  important  office  performed  by  the  mammje  has  led  zoologists  to  arrange  in  the 
same  class,  under  the  term  mammalia,  all  animals  having  an  apparatus  for  lactation.  We 
may  mention  here  another  character  peculiar  to  this  class  of  animals,  because  it  is  in- 
timately connected  with  the  existence  of  mammae,  viz.,  that  all  mammalia  are  vivip- 
arous that  is  to  say,  give  birth  to  their  young  freed  from  all  their  foetal  envelopes. 

The  mammsE  exist  in  both  sexes,  but  are  rudimentary  and  atrophied  in  the  male,  and 
belong  essentially  to  the  female. 

Number. — They  are  two  in  number  in  the  human  species,  which  is  uniparous  ;  in  the 
lower  animals  they  are  generally  double  the  number  of  the  young.  Examples  of  three 
or  four  mammae  in  the  human  subject  are  very  rare,  and  the  supernumerary  mammae 
are  generally  nothing  more  than  simple  nipples,  or,  rather,  masses  of  fat. 

Situation. — They  are  situated  on  the  anterior  and  upper  part  of  the  chest,  the  trans- 
verse enlargement  of  which  in  the  human  subject  is  so  favourable  to  their  development. 
In  the  lower  animals  they  occupy  the  abdominal  region. 

They  are  situated  on  each  side  of  the  median  line,  over  the  interval  between  the  third 
and  the  seventh  ribs.  They  are  therefore  placed  at  the  same  height  as  the  arms,  and 
occupy  this  region,  says  Plutarch,  in  order  that  the  mother  may  be  able  to  embrace  and 
support  her  infant  while  she  is  suckling  it. 

Size. — In  the  male  they  are  rudimentary  during  the  whole  of  life  ;  in  the  female  until 
the  period  of  puberty  only,  when  they  become  much  enlarged  as  the  generative  appara- 
tus is  developed  more  completely.  They  again  increase  in  size  during  pregnancy,  and 
especially  after  delivery  ;  they  become  atrophied  in  old  age.  In  some  females  who  are 
still  young,  the  size  of  the  mammas  by  no  means  corresponds  to  their  statm-e,  strength, 
and  soundness  of  constitution  ;  while,  on  the  other  hand,  it  is  not  uncommon  to  see  thin, 
phthisical  individuals  with  very  large  breasts.  In  judging  of  the  size  of  the  mammae,  we 
must  not  confound  that  depending  upon  the  gland  itself  with  that  due  to  fat.  The  lar- 
gest breasts  are  not  always  those  which  furnish  the  most  milk,  because  their  extreme 
size  often  depends  on  an  accumulation  of  fat,  the  gland  itself  being  small.  The  left  mam- 
ma is  almost  always  a  little  larger  than  the  right. 

Form. — The  mammae  represent  a  semi-sphere  surmounted  by  a  large  papilla  called  the 
nipple. 

The  skin  covering  the  mamma  is  remarkably  delicate.  Surrounding  the  nipple  is  an 
areola  or  aureola  of  a  pinkish  hue  in  young  girls,  but  of  a  brownish  colour  in  most  females 
who  have  borne  children  ;  it  has  also  a  rough  appearance,  owing  to  a  number  of  sebace- 
ous glands,  which  yield  a  kind  of  waxy  secretion  that  prevents  the  irritating  action  of 
the  saliva  of  the  infant.  Morgagni,  Winslow,  and  Meckel  state  that  they  have  observed 
milk  to  escape  from  them  ;  but  if  there  was  no  error  in  their  observations,  it  must  be 
admitted  that,  by  some  unusual  anomaly,  a  lactiferous  duct  opened  at  the  side  of  one  of 
these  little  glands. 

The  mammilla  or  nipple  is  of  a  pinkish  or  brown  colour,  rough,  and,  as  it  were,  crack- 
ed at  the  summit,  and  capable  of  undergoing  a  sort  of  erection ;  it  varies  in  form  and 
size  in  different  subjects  ;  it  is  either  cylindrical  or  conical,  and  sometimes  so  short  that 
the  lips  of  the  infant  cannot  lay  hold  of  it ;  in  certain  cases  it  is  even  depressed.  In  the 
centre  of  the  nipple  we  observe  one  or  more  depressions,  in  which  the  lactiferous  ducts 
open  by  a  variable  number  of  orifices. 

The  papilla  is  provided  also  with  a  great  number  of  sebaceous  glands  having  the  ap- 
pearance of  tubercles,  and  secreting  a  substance  which  prevents  the  nipple  from  being 
chapped  by  the  act  of  sucking  and  the  saliva  of  the  infant.* 

Structure. — The  breasts  consist  of  the  mammary  glandular  tissue  and  of  fat. 

The  Mammary  Gland. — ^When  freed  from  the  fat  by  which  it  is  surrounded,  the  mam- 
mary gland  appears  like  a  mass  flattened  from  before  backward,  and  thicker  in  the  cen- 
tre than  at  its  circumference,  which  is  irregular,  but  less  so  on  the  inside  than  on  the 
outside.  Its  base,  which  is  plane,  and  even  slightly  concave,  rests  upon  the  pectoralis 
major,  and  sometimes  beyond  it  upon  the  serratus  magnus  ;  a  continuation  of  the  fascia 
superficialis  separates  it  from  these  muscles,  to  which  it  adheres  by  very  loose  serous 
cellular  tissue  only,  and  hence  it  is  very  movable. 

The  cutaneous  surface  of  the  mammary  gland  is  very  unequal,  and  forms  alveoli  filled 
by  fat,  by  which  means  the  inequalities  are  concealed. 

The  proper  tissue  of  the  gland  is  considerably  denser  than  that  of  most  glandular  or- 
gans. It  should  be  examined  both  during  lactation,  and  when  that  function  is  not  being 
performed. 

In  the  absence  of  lactation,  the  gland  has  the  appearance  of  a  very  compact,  whitish, 

*  [Sir  A.  Cooper  has  described  numerous  cutaneous  papillae  upon  the  nipple  and  areola  ;  they  are  highly 
*wascular  and  nervous.     He  has  also  shown  that  the  glands  found  in  the  areola  and  at  the  base  of  the  nipple 
nave  branched  ducts,  ending  in  blind  extremities :  in  the  female,  from  one  to  five  open  on  each  tubercle.— 
(Anatomy  of  the  Breast,  1840.)] 


THE    MAMMiE.  473 

fibrous  tissue,  divided  into  unequal  lobes,  which  cannot  be  compared  to  anything  bettei 
than  to  certain  fibrous  tumours  of  the  uterus.  The  granular  structure  proper  to  the  tis- 
sue of  glands  is  not  visible  during  this  state. 

During  lactation,  the  granular  structure  becomes  very  evident.  The  following  are 
the  results  of  my  observations  respecting  it  at  this  period  :  The  glandular  granules  or 
lobules  are  united  into  small  clusters,  forming  flattened  lobes,  placed  one  upon  another. 
From  each  little  lobe  proceeds  an  excretory  duct,  which  may  be  recognised  by  its  white 
colour,  is  easily  injected,  and  is  formed  by  the  union  of  a  number  of  smaller  ducts  cor- 
responding to  the  number  of  lobules.  Having  had  an  opportunity  of  dissecting  the  mam- 
ma of  a  female  recently  delivered,  in  which  the  cellular  tissue  between  the  lobules  was 
infiltrated  with  serum,  the  lobules  themselves,  as  it  were,  dissected,  and  the  lactiferous 
ducts  injected  with  yellowish  coagulated  milk,  I  found  that  some  of  the  lobules  were  iso- 
lated, and,  as  it  were,  pediculated,  while  others  were  collected  into  regular  or  irregular 
clusters.  In  one  of  these  clusters  the  lobules  had  a  circular  arrangement,  small  ducts 
proceeded  from  each  lobule,  and,  passing  from  the  circumference  towards  the  centre  of 
the  circle  like  radii,  opened  into  a  common  efferent  duct,  which  issued  from  the  central 
point.  Another  cluster  was  elongated  and  swollen  at  intervals,  and  in  the  centre  was 
a  duct  which  received  the  smaller  ducts  from  the  several  lobules.  Each  lobule  had  a 
central  cavity,  from  which  a  worm-shaped  mass  of  coagulated  caseous  matter  could  be 
expressed.  When  examined  by  the  simple  microscope,  the  parietes  of  these  cavities 
had  a  spongy  aspect  like  the  pith  of  the  rush,  a  character  which  I  have  already  noticed 
as  belonging  to  all  glandular  organs.* 

The  Fibrous  Tissue  of  the  Mamma. — Besides  the  lobules,  a  large  quantity  of  fibrous  tis- 
sue also  enters  into  the  structure  of  the  gland,  forms  a  complete  investment  for  it,  and 
then  sends  more  or  less  loose  prolongations  into  its  substance,  and  unites  the  lobes  to- 
gether. It  is  to  the  great  quantity  of  fibrous  tissue  that  the  hardness  of  the  mammary 
gland  is  to  be  ascribed.  Sometimes  the  enlargement  of  the  mamma  at  the  time  of  pu- 
berty is  confined  entirely  to  the  fibrous  tissue  ;  in  such  a  case,  the  organ  may  acquire  an 
enormous  size,  the  glandular  tissue  disappears,  and  the  mamma  is  transformed  into  a 
many-lobed  fibrous  mass,  wliich  has  been  sometimes  mistaken  for  a  degenerated  lipoma. 
The  Adipose  Tissue. — The  alveoli  on  the  outer  surface  of  the  mamma  are  filled  with 
masses  of  fatty  tissue,  which  are  separated  by  fibrous  laminae  extending  from  the  gland 
to  the  skin.  The  cells  in  which  these  masses  are  contained  do  not  communicate  with 
each  other,  and  hence  the  frequency  of  circumscribed  abscesses  in  the  mamma.  The 
relative  quantities  of  fat  and  glandular  tissue  have  an  inverse  ratio  to  each  other.  The 
great  size  of  the  mammae  in  some  men  is  owing  to  development  of  the  fatty  tissue. 
Haller  says  that  it  is  an  essential  element  in  the  structure  of  the  gland,  and  that  he  has 
several  times  seen  lactiferous  ducts  arise  from  it. 

The  Lactiferous  Ducts. — If  the  mamma  of  a  female  who  has  died  during  lactation  be 
divided,  the  milk  will  be  seen  to  exude  from  a  number  of  points,  as  from  the  pores  of  a 
sponge  ;  these  points  correspond  to  sections  of  the  thin,  whitish,  semi-transparent  ex- 
cretory ducts  of  the  mammary  glands,  which  are  called  lactiferous,  or  galactophorous  ducts. 
They  arise  from  the  lobules,  and  perhaps,  also,  from  the  fatty  tissue,  as  was  thought  by 
Haller  ;t  they  unite  successively  like  the  veins,  converge  from  the  circumference  to  the 
centre,  traverse  the  substance  of  the  gland,  and  at  length  form  a  variable  number  of 
ducts,  which  reach  the  centre  of  the  gland,  opposite  the  areola.  In  that  situatioa  they 
acquire  their  utmost  size,  and  form  considerable  ampullae  or  dilatations,  between  which 
scarcely  any  intervals  are  left.  According  to  some  anatomists,  the  number  of  these  am- 
pullae is  not  less  than  twenty ;  I  have  never  counted  more  than  ten.  They  are  of  un- 
equal size.  At  the  base  of  the  nipple  they  become  contracted,  straight,  and  parallel,  and 
open  upon  its  summit  by  orifices,  which  are  much  narrower  than  the  ducts  themselves. 
Thus,  then,  although  there  is  no  reservoir  properly  so  called  in  the  mammary  gland,  the 
ampullae  above  described  may  be  regarded  as  such  ;  with  this  difference  only,  that  in- 
stead of  one  reservoir  there  are  several. 

The  lactiferous  ducts,  moreover,  are  surrounded,  both  in  the  mammilla  and  opposite 
the  areola,  with  a  dartoid  tissue,  the  existence  of  which  explains  the  state  of  orgasm 
and  erection  of  the  nipple,  as  well  as  the  expulsion  of  the  milk  in  a  jet  when  the  gland 
is  excited.  There  is  no  trace  of  the  cavernous  structure  described  by  some  anatomists 
as  existing  in  the  nipple.  The  lactiferous  ducts  do  not  communicate  with  each  other  in 
any  part  of  their  course  ;  neither  in  their  terminating  canals,  nor  in  their  ampullae,  nor 
in  their  smaller  ducts  ;  this  may  be  proved  by  mercurial  injections,  or  by  filling  each 
duct  with  a  differently-coloured  injection.  The  mammary  gland,  like  most  others,  is 
therefore  divided  into  a  certain  number  of  distinct  compartments,  which  may  perform 
their  functions  independently  of  each  other. 

Injections  also  show  that  the  lactiferous  ducts  have  no  valves.    Tlieir  structure  is  little 

*  tThe  ultimate  structure  of  the  mammary  gland  consists  of  the  terminations  of  the  lactiferous  ducts  in 
clusters  of  microscopic  cells  within  each  lobule  ;  these  cells  are  round,  and  have  a  diameter  twenty  times  as 
great  as  that  of  the  capillaries  which  ramify  upon  them. 

+  (Our  present  knowledge  of  the  minute  structure  of  glands  has  proved  the  inaccuracy  of  this  supposition  ol 
HaUerJ 

0  o  0 


474 


SPLANCHNOLOGY. 


known.  It  is  generally  admitted  that  they  consist  of  an  internal  membrane  continuoQs 
with  the  skin,  and  which  must  be  analogous  to  the  mucous  membranes,  and  of  an  exter- 
nal fibrous  coat,  which  I  am  inclined  to  regard  as  analogous  to  the  tissue  of  the  dartos. 

The  arteries  of  the  manuna  arise  from  the  thoracic,  especially  that  which  is  called  the 
external  mammary,  also  from  the  intercostals  and  the  internal  mammary. 

The  veins  are  very  large,  and  of  two  kinds,  sub-cutaneous  and  deep  ;  the  latter  accom- 
pany the  arteries,  the  former  are  visible  through  the  skin. 

The  lymphatics  are  very  numerous,  and  enter  the  axillary  glands.  The  older  anato- 
mists admitted  a  direct  communication  between  the  thoracic  duct  and  the  glandular  tis- 
sue of  the  breast ;  but  this  opinion,  suggested  by  the  resemblance  in  colour  between  the 
chyle  and  milk,  is  altogether  erroneous. 

The  nerves  are  derived  from  the  intercostals  and  the  thoracic  branches  of  the  brachial 
plexus. 

Development. — The  mammae  become  visible  after  the  third  month  of  intra-uterine  life. 
At  birth  they  are  more  developed  than  at  a  subsequent  period,  and  contain  a  certain 
quantity  of  miUcy  viscid  fluid.  Until  puberty  the  mammae  of  the  two  sexes  differ  only  in 
the  nipple  being  larger,  and  the  gland  somewhat  larger  in  the  female  than  in  the  male. 

In  the  female,  at  puberty,  they  gradually  acquire  the  size  which  they  subsequently  re- 
tain, their  development  coinciding  with  that  of  the  genital  organs.  Most  commonly  the 
change  precedes,  but  sometimes  it  follows,  the  appearance  of  the  menses. 

The  mammae  of  the  male  also  participate  in  the  development  of  the  generative  appara- 
tus at  the  time  of  puberty,  and  in  some  subjects  even  a  milky  secretion  is  formed.* 

The  manunae  become  atrophied  in  old  age,  and  are  sometimes  replaced  by  fibrous  tis 
sue  ;  in  several  old  women  I  have  found  the  lactiferous  ducts  distended  with  a  dark,  in- 
spissated mucus,  of  a  gelatinous  consistence  which  has  enabled  me  to  trace  the  ducts 
even  to  their  most  delicate  radicles. 


THE  PERITONEUM. 


The  Suh-umhilical  Portion. — The  Supra-umbilical  Portion. — General  Description  and 

Structure. 
The  peritoneum  (nepl,  around,  and  teIvu,  to  extend)  is  a  serous  membrane,  which,  on 
the  one  hand,  lines  the  abdominal  parietes,  and,  on  the  other,  invests  nearly  all  the  vis- 
cera contained  in  the  cavity  of  the  abdomen. 
As  it  enters  into  the  formation  of  almost  all  the  abdominal  viscera,  it  has  been  already 
Fig,  190.  partially  examined  while  describing  them.   It  remains 

for  us  to  demonstrate  these  parts  as  a  whole,  and  for 
this  purpose,  we  shall  suppose  the  membrane  to  com- 
mence at  one  particular  point,  and  shall  trace  it  with- 
out interruption  in  a  circular  course  until  we  again  ar- 
rive at  the  point  from  which  we  started. 

The  peritoneum  is  the  largest  and  most  complica- 
ted of  the  serous  membranes  ;  it  forms,  like  all  of 
them,  a  shut  sac,  the  external  surface  of  which  ad- 
heres to  the  parts  over  which  it  is  reflected,  while  its 
internal  surface  is  free  and  smooth. 

Taking  the  umbilical  region  as  a  point  of  departure, 
we  shall  divide  the  peritoneum  into  two  portions,  a 
superior,  epigastric  or  supra-umbilical,  and  an  inferior 
or  sub-umbilical  portion. 

The  Inferior  or  Sub-umbilical  Portion  of  the  Peritone- 
um..— The  inferior  or  sub-umbilical  portion,  supposed 
to  commence  at  the  umbilicus,  lines  the  whole  of  the 
parietes  of  the  abdomen  (a,  ^^.  190)  below  that  point. 
In  so  doing,  it  is  raised  up  by  the  urachus  and  the  two 
umbilical  arteries,  or,  rather,  by  the  ligaments  repla- 
cing those  arteries,  so  as  to  form  three  falciform  folds, 
one  median  and  two  lateral,  which  converge  towards 
their  termination  at  the  umbilicus,  but  diverge  in  the 
direction  of  the  bladder ;  the  peritoneum  then  dips 
into  the  pelvis,  and  covers  the  fundus,  the  sides,  and 
the  posterior  surface  of  the  bladder  (J),  but  to  a  varia- 
ble extent,  according  as  that  organ  is  distended  oi 
empty.  When  the  bladder  is  contracted,  the  perito- 
neum descends  behind  the  symphysis  ;  when,  on  the 

*  [It  has  been  shown  by  Sir  A.  Cooper,  that  the  mammary  gland 
of  the  male  has  a  system  of  ducts  and  cells  like  those  of  the  fejnals 
gland,  but  very  much  smaller.] 


THE   PERITONEUM.  475 

Other  hand,  it  is  distended  and  rises  into  the  abdomen,  the  peritoneum  retires  before  ii, 
and  the  bladder  then  comes  into  direct  contact  with  the  anterior  wall  of  the  abdomen, 
so  that  it  can  be  reached  by  the  surgeon  without  wounding  the  peritoneum. 

From  the  posterior  surface  of  the  bladder  the  peritoneum  is  reflected  upon  the  other 
pelvic  organs,  being  arranged  differently  in  the  two  sexes.  In  the  male  it  is  reflected 
from  the  bladder  upon  the  rectum,  forming-  two  lateral  semilunar  folds,  called  the  pos- 
terior ligaments  of  the  bladder,  and  a  cul-de-sac  between  them  of  variable  depth,  which 
sometimes  reaches  as  low  as  the  prostate.*  In  the  female  it  is  reflected  from  the  pos- 
terior surface  of  the  bladder  upon  the  neck  of  the  uterus  (m),  forming  a  cul-do-sac  between 
the  two,  so  that  the  inferior  fundus  of  the  bladder  is  entirely  uncovered  by  it.  It  then 
covers  the  two  surfaces  and  the  superior  border  of  the  uterus,  and  forms  two  lateral, 
broad,  transverse  folds  (the  ligamenta  lata),  each  of  which  is  subdivided  superiorly  into 
three  smaller  folds,  the  ala  vespertilionis  or  ala  of  the  broad  ligament,  the  anterior  fold 
corresponding  with  the  round  ligament,  the  middle  one  to  the  Fallopian  tube,  and  the 
posterior  fold  to  the  ovary. 

The  peritoneum  has  no  relation  with  the  front  of  the  vagina  (b),  but  it  covers  the  up- 
per third  of  that  canal  behind  ;  from  thence  it  is  reflected  upon  the  rectum  (r),  and  has 
then  the  same  arrangement  in  both  sexes.  Inferiorly  it  is  limited  to  the  anterior  sur- 
face of  the  gut,  but  superiorly  it  entirely  surrounds  it,  excepting  behind,  where  it  forms 
a  duplicature  known  as  the  mesorectum. 

After  leaving  the  cavity  of  the  pelvis,  the  peritoneum  continues  to  ascend,  so  as  to 
cover  the  posterior  wall  of  the  abdomen ;  in  this  situation  we  shall  examine  it  in  the 
middle  and  at  the  sides. 

In  the  middle  it  passes  in  front  of  the  sacro- vertebral  angle,  then  in  front  of  the  lumbar 
vertebrae,  and  having  arrived  opposite  an  oblique  line,  extending  from  the  left  side  of  the 
second  lumbar  vertebra  to  the  right  iliac  fossa,  it  is  reflected  forward  to  constitute  the 
left  layer  (m)  of  the  mesentery  {neaoq,  middle,  evrepov,  an  intestine) ;  it  immediately  ex- 
pands, so  as  to  correspond  to  the  whole  length  of  the  small  intestine  (i),  lines  the  left 
lateral  half,  the  convex  borders,  and  the  right  lateral  half  of  that  intestine,  and  then  pass- 
ing from  before  backward  (m'),  is  applied  to  the  back  of  the  layer  just  described,  and  in 
this  manner  forms  the  mesentery  (m  m'),  the  largest  of  all  the  duplicatures  of  the  peri- 
toneum, and  remarkable  for  its  resemblance  to  a  plaited  ruffle. 

On  the  left  side,  the  peritoneum,  after  having  formed  the  mesorectum,  then  forms  the 
iliac  Tnesocolon,  a  considerable  fold,  which  allows  great  mobility  to  the  sigmoid  flexure  of 
the  colon.  From  the  sigmoid  flexure  it  is  prolonged  upon  the  left  lumbar  colon,  cover- 
ing the  anterior  five  sixths  of  that  part  of  the  intestine,  and  applying  it  against  the  kidney, 
but  without  forming  any  duplicature  for  it ;  so  that  the  kidney  and  the  colon  are  in  im- 
mediate relation.  Still,  the  left  lumbar  colon  is  not  unfrequently  entirely  surrounded  by 
the  peritoneum,  so  as  to  have  a  duplicature  behind  it,  called  the  left  lunibar  mesocolon. 

Along  the  whole  course  of  the  great  intestine,  the  peritoneum  usually  forms  a  number 
of  small  folds  containing  fat,  and  named  the  appendices  epiploica. 

On  the  right  side  the  peritoneum  arrives  at  the  caecum,  and  may  be  arranged  in  one  of 
two  modes  :  it  either  entirely  invests  that  portion  of  intestine,  which  is  then  very  mo- 
vable ;  or  else,  and  this  is  the  most  common  arrangement,  it  passes  iimnediately  in  front 
of  the  cascum,  which  is  thus  applied  against  the  right  iliac  fossa,  and  is  attached  there 
by  rather  loose  cellular  tissue.  The  peritoneum  sometimes  forms  a  small  mesentery 
for  the  vermiform  appendix,  sometimes  fixes  it  against  the  posterior  surface  of  the 
caecum,  or  against  the  ileum,  or,  lastly,  against  the  lower  portion  of  the  mesentery.  Above 
the  caecum  the  peritoneum  covers  the  right  lumbar  colon,  and  has  the  same  arrange- 
ments as  on  the  left  side. 

Such  is  the  course  of  the  sub-umbilical  portion  of  the  peritoneum. 

The  Superior  or  Supra-umblical  Portion  of  the  Peritoneum. — We  shall  trace  the  superior 
or  supra-umbilical  portion  from  the  umbilicus  to  the  posterior  wall  of  the  abdomen,  op- 
posite to  the  mesentery  and  the  lumbar  mesocolon,  to  which  points  we  have  already 
traced  the  lower  portion. 

Commencing  at  the  umbilicus  and  proceeding  upward,  the  peritoneum  (e)  lines  the  an- 
terior abdominal  parietes ;  on  the  right  side  it  meets  with  the  umbilical  vein,  or  the 
fibrous  cord  to  which  that  vein  is  reduced  in  the  adult,  covers  it,  and  forms  a  falciform 
duplicature,  named  the  suspensory  ligament  of  the  liver,  or  falx  of  the  umbilical  vein ;  this 
fold  is  of  a  triangular  shape,  its  apex  corresponds  with  the  umbdicus,  and  its  base  with 
the  upper  surface  of  the  liver,  which  is  divided  by  it  into  two  lateral  portions  or  lobes,  t 
From  the  umbilicus,  then,  as  from  a  centre,  proceed  four  peritoneal  folds  :  one  superior 
or  ascending,  for  the  umbilical  vein  ;  and  three  descending,  one  for  the  urachus  and  two 
for  the  umbilical  arteries. 

From  the  anterior  wall  of  the  abdomen,  the  peritoneum  is  continued  upon  the  Idwer 

*  The  peritoneum,  forming  the  cul-de-sac  between  tlie  bladder  and  the  rectum,  sometime.s  has  a  fissured  ap- 
pearance, like  that  seen  upon  the  parietes  of  the  abdomen  in  women  who  have  had  many  children. 

t  [Its  lower  free  margin  encloses  the  umbilical  vein,  and  its  upper  or  interior  border  is  attached  to  the  ab- 
dominal parietes.] 


476  SPLANCHNOLOGY. 

surface  of  the  diaphragm  (/),  and  is  arranged  differently  on  the  right  and  left  sides  and 
in  the  middle. 

The  Right  or  Splenic  Portion. — The  peritoneum,  after  having  lined  the  lower  surface 
of  the  diaphragm  as  far  as  the  vertebral  column,  is  reflected  upon  the  posterior  surface 
of  the  vascular  pedicle  of  the  spleen,  covers  the  posterior  half  of  the  internal  surface  of 
that  organ,  its  posterior  border,  the  whole  of  its  external  surface,  the  anterior  half  of 
its  internal  surface,  and  the  anterior  surface  of  its  vascular  pedicle,  from  which  it  is  pro- 
longed upon  the  great  end  of  the  stomach,  and  becomes  continuous  with  the  anterior 
layer  of  the  great  omentum.  The  two  layers  which  are  applied  to  each  other,  one  in 
front  of  and  the  other  behind  the  vessels  of  the  spleen,  constitute  the  gastro-splenic  omen- 
tum. Below  the  spleen,  the  peritoneum  forms  a  horizontal  fold,  or  septum,  by  which 
that  organ  is  separated  from  the  viscera  below  it. 

The  Middle  or  Gastro-epiploic  Portion. — In  the  middle  the  peritoneum  lines  the  lower 
surface  of  the  diaphragm,  as  far  back  as  the  cardiac  extremity  of  the  oesophagus,  is  re- 
flected over  the  anterior  surface  of  the  stomach  (s),  and  descends  into  the  abdomen  in 
front  of  the  arch  of  the  colon  and  the  convolutions  of  the  small  intestine,  to  form  the  an- 
terior layer  (w)  of  the  great  omentum. 

After  descending  towards  the  lower  part  of  the  abdomen  for  a  distance,  which  varies 
in  different  individuals  and  at  different  ages,  it  is  folded  backward  upon  itself,  and  passes 
upward  to  form  the  posterior  layer  (o)  of  the  great  omentum.  Having  arrived  at  the  con- 
vex border  of  the  arch  of  the  colon  (c),  it  covers  the  lower  surface  of  that  intestine,  and 
passes  horizontally  backward  (q)  to  the  anterior  surface  of  the  vertebral  column,  in  front 
of  which  it  is  again  reflected,  and  becomes  continuous  with  the  right  layer  {m')  of  the 
mesentery.  The  horizontal  portion,  which  extends  from  the  arch  of  the  colon  to  the 
vertebral  column,  forms  the  inferior  layer  {q)  of  the  transverse  mesocolon. 

It  follows,  then,  that  the  portion  of  the  peritoneum  which  is  continuous  with  that  upon 
the  anterior  surface  of  the  stomach,  forms  below  that  organ  a  kind  of  bag,  which  has  a 
direct  or  descending  layer,  and  a  reflected  or  ascending  layer,  in  the  interval  between 
which  are  placed  the  stomach  (s),  the  pancreas  (p),  the  duodenum  (d),  and  the  arch  of 
the  colon  (e).  We  shall  afterward  find  that  each  of  these  layers  is  lined  internally  by 
another  layer  of  peritoneum,  so  that  the  great  omentum  consists  of  four  layers  of  serous 
membrane. 

The  Right  or  Hepatic  Portion. — On  the  right  side  the  peritoneum  is  reflected  from  the 
diaphragm  upon  the  convex  surface  of  the  liver  (/),  and  forms  the  coronary  ligament  of 
the  liver  (at  g),  being  continuous  with  the  suspensory  ligament,  the  direction  of  which 
is  at  right  angles  to  its  ovm. 

From  the  convex  surface  of  the  liver,  the  peritoneum  is  reflected  over  its  anterior 
margin,  and  then  upon  its  concave  surface,  investing  the  gall-bladder,  sometimes  almost 
entirely,  but  generally  on  its  lower  surface  only.  At  the  transverse  fissure  it  is  reflect- 
ed downward  in  front  of  the  vessels  of  the  liver,  and  to  the  left  of  those  vessels  reaches 
the  lesser  curvature  of  the  stomach,  and  is  continued  upon  the  anterior  surface  of  that 
organ.  That  portion  of  the  peritoneum  which  extends  from  the  transverse  fissure  to 
the  lesser  curvature  of  the  stomach,  constitutes  the  anterior  layer  (A)  of  the  gastro-hcpatic 
or  lesser  omentum.  To  the  right  of  the  vessels  of  the  liver  and  to  the  right  of  the  gall- 
bladder, the  peritoneum  covers  the  lower  surface  of  this  viscus,  and  becomes  directly 
continuous  with  the  portion  which  covers  the  right  lumbar  colon. 

As  the  peritoneum  is  reflected  from  the  diaphragm  upon  the  right  and  left  extremities 
of  the  liver,  it  forms  two  folds,  one  on  each  side,  called  the  triangular  ligaments  of  the 
liver. 

The  Foramen  of  Winslow  and  Sac  of  the  Omentum. — Behind  the  vessels  of  the  liver, 
and  under  the  anterior  root  of  the  lobulus  Spigelii,  is  an  opening  which  leads  into  a  cav- 
ity situated  behind  the  stomach  and  the  gastro-hepatic  omentum.  This  opening  is  the 
orifice  of  the  omental  sac,  or  the  foramen  of  Winslow  (in  which  a  probe  is  placed  in  the 
figure) ;  the  cavity  is  called  the  posterior  cavity  of  the  peritoneum,  or  the  sac  of  the  omen- 
tum (i).  The  foramen  of  Winslow  is  semicircular,  sometimes  triangular  in  shape,  and 
about  one  inch  in  its  longest  diameter.  It  is  bounded  in  front  by  the  vessels  of  the  liver, 
behind  by  the  vena  cava  inferior,  below  by  the  duodenum,  and  above  by  the  neck  of  the 
gall-bladder,  or,  rather,  by  the  lobulus  caudatus,  or  anterior  root  of  the  lobulus  Spigelii, 
these  several  parts  being  covered  with  peritoneum.  Through  this  opening  the  perito- 
neum enters  the  sort  of  pouch  formed  between  the  two  layers  of  the  great  omentum. 

In  tracing  the  course  of  the  reflected  portion  of  the  peritoneum,  we  shall  commence 
at  this  opening,  and  shall  return  without  interruption  to  the  same  point.  The  perito- 
neum is  first  applied  to  the  posterior  surface  of  the  anterior  layer  of  the  gastro-hepatic 
omentum  already  described,  and  forms  the  posterior  layer  (t)  of  that  omentum ;  it  then 
covers  the  posterior  surface  of  the  stomach  ;  below  that  organ  it  is  applied  (iv)  to  the 
descending  or  anterior  layer  of  the  great  omentum,  behind  and  parallel  to  which  it  passes 
down  ;  having  arrived  at  the  point  where  the  anterior  layer  of  the  great  omentum  is  re- 
flected, the  layer  we  are  now  describing  is  itself  reflected  (x)  in  the  same  manner,  and 
becomes  applied  to  the  anterior  surface  of  the  posterior  layer  of  that  omentum  ;  con- 


THE    PERITONEUM.  477 

tinuing  to  ascend,  it  gains  the  convex  border  of  the  transverse  colon,  covers  the  upper 
surface  of  that  intestine,  and,  farther  back,  is  applied  to  that  layer  of  the  great  omentum 
which  is  continued  over  the  lower  surface  of  the  colon  ;  it  thus  forms  the  upper  {y)  of 
the  two  layers  of  which  the  traiisverse  mesocolon  is  composed.  Having  reached  the 
front  of  the  vertebral  column,  it  leaves  the  inferior  layer  of  the  transverse  mesocolon, 
covers  the  anterior  surface  of  the  third  portion  of  the  duodenum  (d),  the  anterior  surface 
of  the  pancreas  (f>),  the  lobulus  Spigelii  and  the  anterior  part  of  the  vena  cava,  and  ar- 
rives at  the  transverse  fissure  of  the  liver,  opposite  the  foramen  from  which  we  began 
to  trace  it. 

It  follows,  therefore,  that  the  great  omentum,  notwithstanding  its  thinness  and  trans- 
parency, consists  of  four  perfectly  distinct  layers,  two  of  which,  united  together  in  front, 
and  two  behind,  constitute  the  parietes  of  a  cavity  called  the  posterior  cavity  of  the  peri- 
toneum, or  the  sac  of  the  omentum. 

We  may,  however,  describe  the  omentum  in  a  different  mode,  as  follows  :  Two  lay- 
ers of  peritoneum  applied  to  each  other  pass  off  from  the  transverse  fissure  of  the  liver, 
separate  along  the  lesser  curvature  of  the  stomach,  in  order  to  enclose  that  organ,  again 
unite  along  its  greater  curvature,  then  pass  downward,  and,  opposite  the  brim  of  the 
pelvis,  are  reflected  backward  upon  themselves,  and  proceed  upward.  Having  reached 
the  convex  border  of  the  colon,  they  separate  to  receive  that  intestine  between  them, 
become  reunited  at  its  concave  border  to  form  the  transverse  mesocolon,  and  then  sep- 
arate finally.  The  inferior  layer  is  reflected  downward,  to  become  continuous  with  the 
right  layer  of  the  mesentery ;  the  superior  is  reflected  upward,  to  cover  the  third  portion 
of  the  duodenum,  the  pancreas,  and  the  lobulus  Spigelii,  and  then  becomes  continuous 
with  the  rest  of  the  peritoneum  at  the  foramen  of  Winslow.* 

General  Description  of  the  Peritoneum. — From  the  preceding  description,  it  follows  that 
the  peritoneum  forms  a  continuous  membrane,  so  that,  if  it  were  possible  to  unfold  all 
its  duplicatures,  and  to  detach  it  entire  from  the  surface  of  all  the  organs  covered  by  it, 
it  would  form  a  large  membranous  sac  without  an  opening.  Nevertheless,  in  the  fe- 
male there  is  a  remarkable  interruption  at  the  point  corresponding  to  the  free  extremity 
of  the  Fallopian  tube,  in  which  situation  we  find  the  only  example  in  the  body  of  a  serous 
and  mucous  membrane  being  continuous  with  each  other. 

The  peritoneum  has  two  surfaces,  an  external  and  an  internal.  The  internal  surface 
is  free,  smooth,  and  moist,  and  is  the  seat  of  an  exhalant  and  absorbent  process,  which, 
in  the  natural  condition,  exactly  counterbalance  one  another. 

The  external  or  adherent  surface  lines  the  parietes  of  the  abdominal  cavity,  covers  most 
of  the  abdominal  viscera,  of  which  it  forms  the  external  or  common  coat,  and  is  in  con- 
tact with  itself  in  the  different  folds  formed  by  the  peritoneum.  The  attachment  of  this 
surface  is  effected  by  means  of  cellular  tissue,  the  character  of  which  varies  in  different 
situations. 

We  shall  examine  the  external  surface  of  the  portion  of  the  peritoneum  applied  to  the 
abdominal  parietes,  or  the  parietal  peritoneum ;  of  that  upon  the  viscera,  or  the  visceral 
peritoneum ;  and  also  of  that  forming  the  different  folds. 

The  Parietal  Portion  of  the  Peritoneum. — ^Upon  the  diaphragm  it  is  attached  by  a  very 
dense  cellular  tissue  ;  nevertheless,  it  may  be  torn  off  in  dissecting  that  part.  Upon  the 
anterior  wall  of  the  abdomen  it  adheres  most  strongly  opposite  the  linea  alba  and  the 
sheath  of  the  rectus  muscle,  and  more  loosely  opposite  the  crural  arches  than  in  any 
other  part.  Still,  it  is  not  very  difficult  to  separate  the  whole  of  the  membrane  correspond- 
ing to  the  parietes  of  the  abdomen.  In  the  lumbar  region  the  adhesion  is  extremely 
loose,  and  also  in  the  iliac  fossae  on  the  front  of  the  vertebral  column :  the  same  is  the 
case  in  the  cavity  of  the  pelvis. 

The  cellular  tissue  on  the  outside  of  the  peritoneum,  which  most  anatomists  have  re- 
garded as  forming  the  external  tissue  of  that  membrane,  sends  prolongations  through 
the  numerous  openings  with  which  the  walls  of  the  abdomen  are  perforated.  These 
prolongations  connect  the  sub-peritoneal  cellular  tissue  with  that  of  the  lower  extremi- 
ties on  the  one  hand,  and  with  the  cellular  tissue  external  to  the  pleura  on  the  other. 
The  peritoneum  is  supported  throughout  by  a  fibrous  layer,  and  this  accounts  for  the  dif- 
ficulty with  which  abscesses  of  the  abdominal  parietes  open  into  the  cavity  of  the  peri- 
toneum. 

The  Visceral  Portion  of  the  Peritoneum. — Among  the  viscera  of  the  abdomen  some  re- 
ceive a  complete  investment  from  the  peritoneum,  always  excepting  the  point  at  which 
their  vessels  reach  them ;  to  this  class  belong  the  spleen,  the  stomach,  and  the  small 
intestines.  Others  have  a  less  complete  covering,  so  that  a  portion  of  their  surface  is 
in  immediate  relation  with  surrounding  parts  :  of  this  number  are  the  ascending  and  de- 
scending colon  and  the  caecum.  Lastly,  others  have  only  very  slight  relations  with  the 
peritoneum,  which  merely  pass  over  them,  and  do  not  appear  to  enter  into  their  forma- 

*  In  many  subjects  the  existence  of  the  sac  of  the  omentum  may  be  demonstrated  by  introducing  a  large 
catheter  into  the  foramen  of  Winslow,  and  by  blowing  carefully  through  it ;  the  air  will  enter  between  the 
two  anterior  and  the  two  posterior  layers  of  the  great  omentum,  and  form  a  large  and  more  or  less  regular 
'iladder.    For  this  experiment  to  succeed,  the  omentum  must  be  parfectlv  uninjured,  and  free  from  adhesions. 


478  SPLANCHNOLOGY. 

tion :  to  this  class  belong  the  bladder,  the  lower  part  of  the  rectum,  the  pancreas,  the 
two  lower  portions  of  the  duodenum,  and  the  kidneys.  To  the  last-named  organs  the 
peritoneum  is  connected  only  by  very  loose  cellular  tissue. 

The  visceral  portion  of  the  peritoneum  is  not  strengthened  by  the  fibrous  layer  met 
with  in  its  parietal  portion,  and,  therefore,  perforation  of  the  serous  coat  of  the  viscera 
is  much  more  common  than  perforation  of  the  parietal  portion  of  the  serous  membrane. 

The  Folds  of  the  Peritoneum. — Among  the  folds  of  the  peritoneum,  most  of  which  have 
been  already  described,  and  which  need  be  only  recapitulated  here,  some  bear  the  name 
of  ligaments,  viz.,  the  triangular,  coronary,  and  falciform  ligaments  of  the  liver,  the  pos- 
terior ligaments  of  the  bladder,  and  the  broad  ligaments  of  the  uterus. 

Others  are  called  mesenteries,  viz.,  the  mesentery,  properly  so  called,  or  the  mesentery 
of  the  small  intestine,  the  transverse  mesocolon,  the  right  and  left  lumbar  mesocolon 
when  they  exist,  the  ihac  mesocolon,  and  the  mesorectum.  With  these  we  should  in- 
clude the  duplicature  extending  from  the  transverse  fissure  of  the  liver  to  the  lower  cur- 
vature of  the  stomach,  and  known  as  the  lesser  omentum ;  it  really  constitutes  the  me- 
sogastrium. 

Lastly,  there  are  certain  folds,  named  omenta  or  epiploa  {em,  upon,  n?Ju,  to  float),  viz., 
the  great,  or  gastro-colic,  small,  or  gastro-hepatic,  gastro-splenic,  and  colic  omenta.* 
With  this  class  we  may  connect  the  appendices  epiploicae.  It  may  be  well  to  make  a 
few  observations  upon  the  great  and  lesser  omenta. 

The  Great  Omentum. — The  great  or  gastro-colic  omentum,  so  called  because  it  is  at- 
tached, on  the  one  hand,  to  the  stomach,  and  on  the  other  to  the  colon,  scarcely  exists 
in  the  new-born  infant ;  it  is  gradually  developed  as  age  advances,  and  about  the  period 
of  the  termination  of  growth  it  reaches  to  the  brim  of  the  pelvis.  It  has  been  remarked 
that  it  descends  a  little  lower  on  the  left  than  on  the  right  side. 

When  the  stomach  and  the  colon  are  distended,  this  omentum  is  reduced  to  a  more  or 
less  narrow  border  extending  along  the  arch  of  the  colon. 

It  presents  also  a  number  of  individual  varieties :  sometimes  it  is  very  regularly  sus- 
pended in  front  of  the  intestinal  convolutions ;  sometimes  it  is  folded  upon  itself,  and 
carried  to  one  side  or  the  other ;  occasionally  it  adheres  at  some  point,  becomes  stretch- 
ed hke  a  cord,  and  may  then  give  rise  to  strangulation ;  and,  lastly,  it  is  not  very  rare  to 
find  it  turned  upward  and  backward  between  the  diaphragm  above  and  the  stomach  and 
liver  below. 

It  is  so  transparent  and  thin  that  it  is  difficult  to  conceive  it  to  be  formed  of  four  lay- 
ers. In  some  individuals  it  is  even  perforated  with  holes  like  a  piece  of  lace.  The 
great  omentum  is  found,  in  very  fat  persons,  to  be  loaded  with  an  immense  quantity  of 
adipose  tissue,  deposited  chiefly  along  the  vessels ;  so  that  it  may  acquire  a  very  con- 
siderable size,  and  a  weight  of  several  pounds. 

The  great  omentum  has  an  anterior  and  posterior  surface,  both  of  which  are  free,  an 
upper  adherent  border,  a  lower  border,  free,  convex,  and  more  or  less  sinuous,  which  cor- 
responds with  the  crural  arches,  and  the  internal  openings  of  the  inguinal  canals ;  it  is, 
therefore,  very  often  found  in  hernial  sacs. 

The  lower  border  is  more  liable  to  adhesions  than  any  other  part  of  the  omentum. 
The  lateral  borders  have  nothing  remarkable ;  they  proceed  parallel  to  the  ascending  and 
descending  portions  of  the  colon,  which  are  sometimes  covered  by  them. 

The  arteries  of  the  great  omentum  are  furnished  by  the  right  and  left  gastro-epiploic 
arteries ;  they  descend  vertically  between  its  two  anterior  layers,  scarcely  diminishing 
in  caliber.  At  its  lower  border  they  turn  upward,  and  ascend  between  the  two  posterior 
layers  as  far  as  the  arch  of  the  colon,  where  they  communicate  with  the  arteries  of  that 
intestine. 

The  veitis  follow  the  same  course  as  the  arteries,  and  assist  in  forming  the  vena  portee. 

Some  lymphatic  glands  are  found  in  the  great  omentum  along  the  curvatures  of  the 
stomach  and  the  arch  of  the  colon. 

Nerves. — Some  nervous  filaments  from  the  solar  plexus  can  be  traced  upon  the  arter- 
ies of  the  omentirai ;  it  is  doubtless  from  them  that  the  epiploon  derives  its  peculiar  sen- 
sibility, and  on  them  that  the  phenomena  of  strangulation  depend  when  it  is  constricted 
in  a  hernia. 

The  uses  of  the  omentum  are  not  known. 

The  Lesser  Omentum. — The  lesser  omentum,  a  true  mesentery,  the  mesogastrium,  pre- 
sents a  lower  concave  border,  attached  to  the  lesser  curvature  of  the  stomach,  and  an 
upper  border,  attached  to  the  transverse  fissure  of  the  liver,  to  that  part  of  the  antero- 
posterior fissure  which  is  behind  the  transverse  fissure,  and  also  to  the  oesophagus  and 
the  diaphragm ;  its  right  border  contains  the  ducts  and  vessels  of  the  liver,  and  behind 
the  border  thus  formed  is  seen  the  foramen  of  Winslow ;  on  the  left  it  is  bounded  by  the 
cesophagus.t 

'  [The  colic  omentum  consists  of  two  layers  of  peritoneum,  with  intermediate  vessels  and  fat,  which  de- 
scend, behind  the  great  omentum,  from  the  upper  part  of  the  ascending  colon.] 

t  [The  cellular  tissue  surrounding  the  vessels,  ducts,  and  nerves,  contained  between  the  layers  of  this  small 
omentum,  has  been  described  as  giving  origin  to  Glisson's  capsule.] 


THE  HEART.  479 

IStruetin-e  of  the  Peritoneum. — ^The  peritoneum,  like  all  other  serous  membranes,  has 
neither  arteries,  veins,  nor  nerves.  Those  which  are  contained  within  the  omenta  and 
the  mesentery  do  not  properly  belong  to  this  membrane.  The  finest  capillary  injections, 
either  natural  or  artificieil,  form  an  extremely  delicate  network  below  the  peritoneum, 
but  never  penetrate  it.* 


ANGEIOLOGY. 

Definition  and  Objects  of  Angeiology. 

Angeiologt  {ayyelov,  a  vessel)  is  that  division  of  anatomy  which  treats  of  the  orgauL 
of  the  circulation. 

The  circulating  system  consists  of  a  central  organ,  the  heart,  the  agent  for  propelling 
the  blood  ;  of  the  arteries,  vessels  through  which  the  blood  is  conveyed  from  the  heart 
to  all  parts  of  the  body ;  of  the  veins,  through  which  the  blood  is  returned  from  all  parts 
of  the  body  to  the  heart  again ;  and,  lastly,  of  the  lymphatic  vessels,  appendages  of  the 
venous  system,  into  which  their  contents  are  ultimately  poured. 

THE  HEART. 

General  Description. — External  and  Internal  Conformation. — Structure. — Development. — 
Functions. — The  Pericardium. 

Dissection. — In  order  to  study  the  external  conformation  of  the  heart,  inject  the  cavi- 
ties of  the  right  side  of  that  organ  by  the  pulmonary  artery,  or  by  one  of  the  venae  cavae, 
taking  care  to  tie  the  other ;  the  cavities  of  the  left  side  may  be  filled  from  the  aorta,  or 
one  of  the  pulmonary  veins. 

Tallow,  wax,  and  glue-size  are  the  most  suitable  materials  for  this  purpose. 

The  heart  {Kapdia),  the  central  part  of  the  circulating  apparatus,  is  a  hollow  muscular 
organ,  divided  into  several  compartments,  and  intended  for  propelling  through  the  arter- 
ies into  all  parts  of  the  body  the  blood  which  is  poured  into  it  from  the  veins. 

The  heart  is  one  of  the  most  important  organs  in  the  body.  In  a  zoological  point  of 
view,  the  presence  or  absence  of  a  heart,  and  the  complexity  or  simplicity  of  its  struc- 
ture, deserve  particular  attention,  because  such  variations  in  regard  to  the  central  organ 
of  the  circulation  are  accompanied  by  very  great  modifications  in  the  entire  organism.! 

Congenital  absence  of  the  heart  is  extremely  rare,  and  is  always  accompanied  with 
other  malformations,  more  especially  with  absence  of  the  brain.  These  deficiencies  are 
incompatible  with  life. 

Number. — Man  and  vertebrated  animals  have  only  one  heart ;  in  moUusca  it  is  double, 
or  even  triple.  This  plurality  of  hearts,  instead  of  being  an  index  of  perfection,  should 
be  regarded  as  a  subdivision,  and  less  perfect  condition  of  the  organ.  We  shall  see  that 
man,  as  well  as  mammalia  and  birds,  has,  in  reality,  two  hearts  united  into  one. 

Situation. — The  heart  is  situated  at  the  junction  of  the  upper  third  with  the  lower  two 
thirds  of  the  body ;  hence  the  upper  parts  of  the  system  are  more  immediately  under  the 
influence  of  this  important  organ,  t 

The  heart  (/,  fig.  170 ;  o,fig.  171)  occupies  the  middle  of  the  thoracic  cavity ;  it  is  sit- 
uated in  the  mediastinum,  in  front  of  the  vertebral  column,  behind  the  sternum,  which 
forms  a  kind  of  shield  for  it,  and  beyond  which  it  projects  on  the  left  side ;  it  is  placed 
between  the  lungs,  and  above  the  diaphragm,  by  which  it  is  separated  from  the  abdom- 
inal viscera. 

It  is  retained  in  this  situation  by  the  pericardium  (p  p,fig.  170),  a  fibro-serous  cover- 
ing, which  is  itself  closely  adherent  to  the  diaphragm  (x) ;  by  the  pleurae  {q  q),  which  are 
reflected  on  each  side  of  it,  to  form  the  parietes  of  the  mediastinum ;  and,  lastly,  by  the 
great  vessels  which  pass  out  or  enter  at  its  base. 

*  [The  basis  of  the  peritoneum  is  cellular  tissue  ;  its  smooth  surface  is  covered  with  a  squamous  epithelium.] 
t  Vertebrata  and  mollusca  are  the  only  animals  which  are  provided  with  a  heart.     Mammalia  and  birds 

alone  possess  a  double  heart,  i.  e.,  a  heart  with  two  auricles  and  two  ventricles.  Fishes  and  reptiles  have  a 
simple  heart,  t.  e.,  a  heart  with  only  one  auricle  and  one  ventricle,  this  ventricle  being  pulmonary  in  fishes, 
and  both  systemic  and  pulmonary  in  reptiles.* 

t  The  distance  from  the  heart  to  the  brain  varies  in  different  individuals,  according  to  the  length  of  the  tho- 
rax and  the  neck.  This  difference  may  amount  to  two  inches,  and  may  exercise  some  influence  upon  the  cere- 
bral circulation.  In  consequence  of  this  observation,  extreme  shortness  of  the  neck  has  been  regarded  as  a 
predisposing  cause  of  apoplexy. 

*  [A  central  pulsating  vessel  is  found  in  some  of  the  higher  radiata,  and  in  the  articulata ;  in  some  of  the 
latter  it  constitutes  a  strong  muscular  ventricle,  but  the  addition  of  a  systemic  auricle  to  this  ventricle  is  first 
observed  in  the  mollusca ;  in  the  invertebrata,  generally,  the  ventricle  is  entirely  systemic :  in  the  higher  ce- 
phalopods  there  are  two  branchial  hearts.  In  fishes  the  heart  consists  of  a  systemic  auricle  and  a  pulmonary 
ventricle,  and  is  preceded  by  a  sinus  venosus,  and  followed  by  a  bulbus  arteriosus.  In  the  early  condition  of 
the  batrachia  the  same  conformation  exists  ;  but  in  their  adult  state,  and  also  in  all  reptilia,  there  are  two 
auricles  and  one  ventricle,  the  additional  auricle  being  pulmonary,  i.  e.,  receiving  the  blood  from  the  lungs. 
In  the  higher  reptilia,  the  single  ventricle,  which  is  both  systemic  and  pulmonary,  is  divided  by  an  imperfect 
leptura  ascending  from  the  apex  of  the  heart.  In  the  crocodilus  lucius,  as  well  as  in  birds  and  mammalia, 
this  interventricular  septum  is  complete,  so  that  in  them  the  heart  is  divided  into  two  auricles  and  two  ventri- 
cles, the  cavities  of  one  side  being  systemic,  and  of  the  other  pulmonary.] 


ANGEIOLOGY. 

These  means  of  attachment  are  not  such  as  to  prevent  the  heart  from  undergoing  re 
markable  changes  of  position,  depending  upon  peculiar  attitudes,  upon  shocks  acting  on 
the  body,  or  upon  diseases  of  the  surrounding  organs.  Thus,  in  a  case  of  hydrothorax 
on  the  left  side,  the  apex  of  the  heart  struck  against  the  right  side,  and  gave  rise  to  the 
suspicion  that  the  viscera  were  transposed. 

Size  and  Weight. — Neither  the  size  nor  the  weight  of  the  heart  can  be  estimated  with 
exactness,  on  account  of  the  numerous  individual  varieties  in  both.  It  is  very  difficult  to 
determine  the  limits,  in  either  the  one  or  the  other,  between  a  healthy  and  a  morbid  con- 
dition ;  and  a  heart  which  would  be  considered  normal  in  one  individual  would  be  re- 
garded as  hypertrophied  in  another. 

The  defects  of  the  method  proposed  by  Laennec  for  obtaining  an  approximative  esti- 
mate of  the  size  of  the  heart,  by  comparing  it  with  that  of  the  closed  hand  of  the  samo 
subject,  afford  sufficient  evidence  of  the  difficulty  of  arriving  at  an  accurate  result  in  this 
matter.* 

No  organ  in  the  body  is  more  subject  to  enlargement  than  the  heart ;  when  caused  by 
dilatation  of  the  cavities,  it  constitutes  aneurism  of  the  heart  {dilatation) ;  when  due  to 
thickening  of  the  parietes,  it  is  termed  hypertrophy.  When  enlargement  occurs  from 
both  these  causes,  the  heart  acquires  an  enormous  size,  and  has  been  called  bullock's 
heart  (hypertrophy  with  dilatation). 

The  size  of  the  heart  may  be  estimated  directly  by  ascertaining  the  quantity  of  water 
displaced  by  it,  and  by  admeasurement ;  it  may  also  be  determined,  in  an  approximate 
manner,  by  its  weight,  which  bears  a  certain  relation  to  the  size. 

In  making  these  estimates,  it  is  necessary  to  distinguish  the  size  and  weight  depend- 
ant upon  thickness  of  the  parietes  of  the  heart,  from  the  increase  occasioned  by  blood 
contained  in  its  cavities.  In  order  to  obtain  comparative  results  upon  this  point,  the 
heart  must  be  weighed  and  measured  both  in  its  empty  and  its  distended  state.  The 
average  weight  of  the  empty  heart  is  from  seven  to  eight  ounces.  Some  atrophied  hearts 
do  not  weigh  more  than  two  ounces :  dilated  and  hypertrophied  hearts,  when  empty, 
may  weigh  twenty-two  ounces.  The  ordinary  weight  of  the  heart  distended  with  tal 
low  is  twenty-four  ounces.  I  have  seen  dilated  hearts,  also,  filled  with  tallow,  which 
weighed  three  pounds. 

As  to  the  admeasurement,  we  shall  apply  it  in  succession  to  the  ventricles  and  to  the 
auricles. 

Form,  Direction,  and  Divisions. — The  heart  has  the  form  of  a  flattened  cone,  the  axis 
of  which  is  directed  obliquely  from  above  downward,  from  the  right  to  the  left  side,  and 
from  behind  forward.  This  direction,  which  is  peculiar  to  the  human  species  (for  in  the 
lower  animals  the  heart  is  vertical),  appears  to  have  some  relation  to  the  erect  position. 
The  heart  is  not  symmetrical  in  reference  to  the  median  line  of  the  body,  nor  yet  in  re- 
gard to  its  own  axis. 

The  general  relations  of  the  heart  will  be  indicated  when  we  describe  the  pericardium. 
I  shall  here  simply  state  that  the  heart  is  in  relation  with  the  left  lobe  of  the  lungs,  which 
is  deeply  notched  to  receive  it ;  that  that  portion  of  the  heart  which  is  uncovered  in  front 
between  the  lungs,  after  the  sternum  and  the  ribs  have  been  removed,  is  extremely  vari- 
able in  different  subjects  ;  that  independently  of  the  volume  of  the  heart,  the  adhesions 
of  the  lungs  exercise  a  very  great  influence  upon  the  extent  of  these  direct  relations  of 
the  heart  with  the  anterior  part  of  the  sternum.  In  an  old  woman,  whose  lungs  were 
closely  adhering  to  the  walls  of  the  thorax,  the  anterior  face  of  the  heart  was  almost  en- 
tirely bare  behind  the  sternum  and  the  cartilages  of  the  ribs  on  the  left  side.t  That  the 
posterior  face  of  the  heart  deserves  the  name  of  vertebral  surface  just  as  well  as  that 
of  diaphragmatic  surface  ;  that  this  surface  occasions  a  marked  impression  upon  the  liv- 
er ;  that  the  relations  of  the  posterior  surface  of  the  heart  with  the  oesophagus  are  such 
as  will  cause  the  distended  oesophagus  to  raise  the  corresponding  portion  of  the  pericar- 
dium, and  that  the  posterior  surface  of  the  heart  is  not  only  separated  from  the  vertebral 
column  by  the  oesophagus,  but  also  by  the  aorta,  which  is  situated  between  the  oesopha- 
gus and  the  bodies  of  the  dorsal  vertebrae. 

The  heart  is  divided  into  ventricles  and  auricles.  The  ventricles  (Jt  o,figs.  191,  192) 
constitute  the  chief  part,  in  some  measure  the  body  of  the  organ,  the  conical  form  of 
which  is  determined  by  them  ;  the  auricles  (m  n)  are  a  kind  of  appendices,  which  can  be 
well  seen  only  when  the  heart  is  raised ;  they  occupy  the  base  of  the  organ  ;  the  limit 
between  the  auricles  and  the  ventricles  is  indicated  by  a  circular  furrow. 

External  Conformation  of  the  Heart. 
The  External  Surface  of  the  Ventricles. 
The  external  surface  of  the  ventricles,  or  the  ventricular  portion  of  the  heart,  called  also 

*  The  large  hand  of  a  workman  does  not  imply  the  existence  of  a  larger  heart  than  the  small  hand  of  a  fe- 
male, or  of  a  man  exempt  from  manual  labour. 

t  The  heart  descends  as  far  as  the  middle  portion  of  the  xiphoid  appendix.  The  upper  half  of  this  appendix 
is,  therefore,  in  direct  relation  with  the  heart,  and  the  inferior  half  in  direct  relation  with  the  liver.  Should 
not  this  circumstance  be  of  some  weight  in  explaining  the  acute  pains  by  which  a  pressure  upon  this  appendix 
u  accompanied  ? 


THE    HEART.  48'! 

by  the  ancients  the  arterial  portion,  because  the  arteries  arise  from  it,  presents  for  our 
consideration  an  anterior  and  an  inferior  surface,  a  right  and  a  left  border,  a  base  and  an 
apex. 

The  anterior  or  sternal  surface  {Jig.  191)  is  convex,  and  is  divided  into  two  unequal 
parts,  a  larger  on  the  right,  and  a  smaller  on  the  left  side,  ^^  191_ 

by  the  anterior  furrow  of  the  heart  (e  b),  which  passes  verti- 
cally from  the  base  towards  the  apex,  is  occupied  by  the  an- 
terior coronary  artery,  and  is  often  obscured  by  fat.  All 
that  part  of  the  organ  which  is  to  the  right  of  the  furrow  be- 
longs to  the  right  ventricle  (I),  all  on  the  left  belongs  to  the 
left  ventricle  (o).  The  furrow  itself  corresponds  to  the  sep- 
tum between  the  ventricles. 

This  surface,  or,  rather,  the  pericardium  which  covers  it, 
is  in  relation  with  the  sternum,  more  especiedly  in  that  part 
which  hes  to  the  right  of  the  furrow  ;  also  with  the  fourth, 
fifth,  and  sixth  costal  cartilages  of  the  left  side,  and  with  the 
lungs,  which  cover  it  more  or  less  completely.  It  should 
be  remarked  that,  in  large  hearts,  this  surface,  or  its  peri- 
cardium, corresponds  immediately  to  the  sternum,  while  in 
the  natural  state  it  is  situated  at  some  distance  from  that 
bone.  The  relations  of  the  heart  with  the  anterior  wall  of 
the  thorax  enable  us  to  examine  its  condition  by  means  of 
percussion  and  auscultation. 

The  inferior  or  diaphragmatic  surface  {fig.  192)  is  plane  and  horizontal ;  it  rests  upon 
the  diaphragm,  which  forms  a  sort  of  floor  for  it,  and  separates  it  from  the  hver  and  the 
stomach.  Like  the  anterior  surface,  it  is  marked  by  a  longitudinal  furrow,  the  posterior 
furrow  of  the  heart  {e  i),  which  is  traversed  by  vessels  and  concealed  by  fat.  It  differs 
from  the  anterior  furrow  in  running  parallel  to  the  axis  of  the  heart,  and  dividing  its 
diaphragmatic  surface  into  two  nearly  equal  parts,  excepting  near  the  apex.  In  conse- 
quence of  the  relations  of  this  surface,  pidsations  are  observed  in  the  epigastrium,  which 
are  sometimes  much  more  distinct  than  those  felt  upon  the  anterior  wall  of  the  thorax. 
Another  result  of  these  relations  is,  that  the  same  meaning  is  attached  to  the  terms 
scrobiculus  cordis  and  pit  of  the  stomach,  and  also  to  the  expressions  pain  at  the  heart,  pain 
at  the  stomach,  4-c. 

The  right  or  lower  border  is  thin  and  horizontal,  and  rests  upon  the  diaphragm ;  it  is 
straight  near  tlft  apex,  but  becomes  convex  towards  the  base.  The  left  border  (o  b,  fig. 
191)  is  very  thick,  convex,  and  almost  vertical;  it  resembles  a  surface  rather  than  a 
border,  and  corresponds  to  the  left  lung,  which  is  deeply  notched  to  receive  it. 

The  base  of  the  ventricular  portion  of  the  heart  is  turned  upward,  backward,  and  to  the 
right  side.  From  it  arises,  upon  an  anterior  plane,  an  artery,  which  immediately  passes 
from  the  right  to  the  left ;  this  is  the  pulmonary  artery  {k) ;  the  portion  of  the  ventricle 
from  which  it  proceeds  forms  a  prominence  on  the  right  side  of  the  anterior  furrow  of 
the  heart,  and  is  prolonged  towards  the  left,  becoming  narrower  at  the  same  time,  so  as 
to  form  a  funnel-shaped  projection  {infundibulum,  conus  arteriosus)  {a),  extending  a  little 
beyond  the  base  of  the  ventricles.  Upon  a  second  plane  we  find  the  aorta  (/),  the  origin 
of  which,  from  the  left  ventricle,  is  concealed  by  the  funnel-shaped  prolongation  of  which 
we  have  just  spoken.  On  a  third  plane  we  find  a  circular  furrow  (o  u,  fig.  195),  separa- 
ting the  auricles  from  the  ventricles.  Its  posterior  half  is  occupied  by  the  coronary  ar- 
teries and  veins,  and  the  anterior  and  posterior  furrows  of  the  heart  terminate  in  it  at 
right  angles. 

This  circular  furrow  at  first  sight  appears  to  be  superficial,  but  is  very  deep  in  its  pos- 
terior half  If  we  dissect  carefiiUy  down  to  the  bottom  of  this  furrow,  it  is  found  that 
the  base  of  each  ventricle  is,  as  it  were,  turned  inward,  so  as  to  be  in  contact  by  a  broad 
surface  with  the  base  of  the  auricle.  We  find,  also,  that  the  base  of  the  ventricles  is  cut 
obUquely,  and  hence  the  anterior  surface  of  the  heart  is  longer  than  the  posterior  surface. 
The  difference  in  length  between  these  two  surfaces  is  about  fifteen  lines  upon  the  right, 
and  from  nine  to  ten  Unes  upon  the  left  ventricle.  Thus,  in  a  heart  of  the  ordinary  size, 
the  length  of  the  ventricles  in  front  was  three  inches  three  lines,  and  behind  two  inches 
three  lines.  In  a  very  large  heart  the  length  in  front  was  four  inches,  and  behind  only 
three.  The  circumference  of  the  base  of  an  injected  heart,  of  the  average  size,  measured 
ten  inches  ;  that  of  a  large  heart  was  thirteen  inches  six  lines. 

The  apex  {h)  or  point  of  the  heart  is  slightly  curved  backward  in  the  majority  of  sub- 
jects, and  is  notched  opposite  the  junction  of  the  two  longitudinal  furrows.  This  notch, 
which  is  partially  concealed  by  vessels  and  adipose  tissue,  divides  the  apex  of  the  heart 
into  two  unequal  portions  ;  a  right  and  a  smaller,  belonging  to  the  right  ventricle,  and  a 
left  and  larger  portion,  belonging  to  the  left  ventricle.  The  relative  size  of  the  two  por- 
tions of  the  apex  of  the  heart  is  not  constant.  In  some  cases  of  hypertrophy  of  the  left 
ventricle,  the  apex  of  the  heart  is  entirely  formed  by  it ;  in  other  cases,  on  the  contrary 
the  apex  of  the  heart  is  nearly  equally  subdivided. 

Ppp 


482  ANOEIOLOGY. 

The  apex  of  the  heart  is  directed  forward,  downward,  and  to  the  left,  and  corresponds 
to  the  cartilages  of  the  fifth  and  sixth  ribs  of  the  left  side,  and  therefore  to  the  region  of 
the  corresponding  mamma  ;  the  left  lung  is  notched  opposite  the  apex  of  the  heart,  so 
that  the  latter  strikes  directly  against  the  parietes  of  the  thorax. 

The  External  Surface  of  the  Auricles. 
The  attricles  (m  n,figs.  191, 192),  forming  the  auricular  portion  of  the  heart,  are  saccular 
cavities  in  which  the  veins  terminate  ;  they  may,  in  fact,  be  regarded  as  dilatations  of 
those  vessels,  and  hence  this  portion  of  the  heart  is  called  the  venous  portion,  in  contra- 
distinction to  the  ventricles.  They  are  situated  upon  the  hindermost  portion  of  the 
base  of  the  heart  (fig.  192). 

Their  size  varies  in  different  individuals  ;  in  an  injected  heart,  the  average  height  of 
the  auricular  portion  is  two  inches ;  its  antero-posterior  diameter  is  nearly  the  same  ; 
and  when  the  auricles  are  distended,  its  transverse  diameter  extends  beyond  the  tcl 
tricles  on  each  side. 

The  shape  of  the  auricular  portion  of  the  heart,  which  can  only  be  accurately  deter 
mined  by  means  of  injection,  is  irregularly  cuboid.  It  therefore  presents  several  sur 
faces  ;  its  anterior  surface  is  situated  on  a  plane  much  farther  back  than  that  of  the  front 
of  the  ventricles  {fig.  191).  It  is  concave,  and  describes  three  fourths  of  a  circle,  so  as 
to  embrace  the  aorta  and  the  pulmonary  artery,  being  moulded  upon  those  vessels,  and 
completely  concealed  by  them.  The  anterior  surface  of  the  auricular  portion  has  no 
anterior  furrow  along  the  middle  line. 
The  posterior  surface  (fig.  192)  is  convex,  and  is  continuous  with  the  inferior  surface 
of  the  ventricles ;  it  presents  a  vertical  furrow,  which  is 
prolonged  upward  from  the  posterior  furrow  of  the  ventri- 
cles, then  deviates  to  the  left  side,  and  forms  a  curve,  the 
concavity  of  which  is  directed  towards  the  right ;  it  corre- 
sponds to  the  septum  of  the  auricles.  Immediately  to  the 
right  of  this  furrow  we  find  the  termination  of  the  vena  cava 
inferior  (r),  and  lower  down,  that  of  the  great  coronary  vein. 
The  posterior  surface  of  the  auricles  is  turned  towards  the 
vertebral  column,  from  which  it  is  separated  by  the  oesopha- 
gus and  the  aorta. 

The  superior  surface  of  the  auricular  portion  forms  the 
highest  part  of  the  heart,  and  is  directed  backward  and  to- 
wards the  right  side.  It  is  divided  by  a  furrow,  which  is 
convex  on  the  right  side,  is  continuous  with  the  furrow  upon 
the  posterior  surface,  and,  like  it,  corresponds  to  the  inter- 
auricular  septum.  Upon  this  surface  we  find  the  termina- 
tions of  five  different  veins ;  one  only  of  these  is  to  the  right 
of  the  furrow,  viz.,  that  of  the  vena  cava  superior  (d,fig.  191) ;  the  other  four  are  on 
the  left  of  the  furrow,  and  are  those  of  the  four  pulmonary  veins,  which  are  arranged  in 
pairs  (c  c,fig.  192),  two  at  the  extreme  left  of  the  auricles  belonging  to  the  left  pulmona- 
ry veins,  and  two  immediately  in  the  neighbourhood  of  the  posterior  furrow  belonging  to 
the  right  pulmonary  veins.  This  surface  corresponds  to  the  bifurcation  of  the  trachea, 
which,  as  it  were,  rides  upon  it. 

The  extremities  of  the  auricles,  or  the  aurievJee,  are  free,  and  somewhat  resemble  the 
pendulous  portion  of  a  dog's  ear  ;  hence  the  term  auricles.  They  are  indented  like  a 
cock's  comb  ;  the  right  auricula  is  anterior,  the  left  posterior. 

The  right  auricula  {c,fig.  191)  is  broader  and  shorter  than  the  left  ;  it  is  triangular  and 
concave,  so  as  to  embrace  the  aorta,  in  front  of  which  it  projects  ;  the  left  auricula  (i)  is 
narrower  and  longer,  it  is  sinuous,  and  curved  twice  upon  itself  like  an  italic  S ;  it  em- 
braces the  pulmonary  artery,  and  terminates  opposite  the  highest  part  of  the  anterior  fur- 
row of  the  ventricles. 

The  right  auricula  is  continuous  with  the  rest  of  the  corresponding  auricle,  vdthout 
any  well-marked  line  of  separation ;  but  the  left  auricula  is  very  distinct  from  its  auricle  ; 
and  upon  this  latter  side,  the  distinction  pointed  out  by  Boerhaave,  between  the  sinuses 
and  the  auricles  properly  so  called,  may  be  particularly  observed :  according  to  him,  the 
sinus  constitutes  the  body  of  the  auricle,  and  may  be  regarded  as  a  dilatation  of  the  veins, 
while  the  auricular  appendix  forms  the  proper  auricle. 

The  Internal  Conformation  of  the  Heart. 

The  heart  is  divided  internally  into  four  cavities,  which  are  separated  from  each  oth- 
er by  complete  or  incomplete  septa ;  two  of  these  cavities  belong  to  the  auricles,  and  two 
to  the  ventricles.  There  are  a  right  ventricle  and  auricle,  and  a  left  ventricle  and  auri- 
cle. The  auricle  and  ventricle  of  the  same  side  are  separated  by  incomplete  septa  or 
valves,  and  communicate  with  each  other.  The  cavities  of  the  opposite  sides  are  sep- 
arated by  complete  septa,  and  do  not  communicate.  Tlie  heart  is  therefore,  in  this  lat- 
ter respect,  truly  double.    The  right  ventricle  and  auricle  constitute  the  right  heart,  also 


THE    HEART.  4^ 

named  the  cmur  d.  sang  noir,  from  the  colour  of  the  blood  which  it  contains ;  and  the  pul- 
monary heart,  because  it  propels  the  blood  into  the  lungs.  The  left  ventricle  and  auricle 
constitute  the  left  heart,  called  also  the  caur  a  sang  rouge,  or  the  aortic  heart,  because  it 
throws  the  blood  into  the  aorta. 

The  Internal  Conformation  of  the  Ventricles. 

Dissection. — In  order  to  obtain  a  general  idea  of  the  internal  conformation  of  the  heart, 
make  a  series  of  sections  at  right  angles  to  its  length,  or  else  make  an  incision  along  its 
borders  parallel  to  its  long  axis. 

To  obtain  a  more  exact  notion  of  the  ventricles,  make  a  V-shaped  incision  in  the  right 
ventricle,  letting  one  branch  of  the  incision  extend  along  the  anterior  furrow,  and  tte 
other  along  the  right  border,  while  the  angle  at  which  they  meet  should  correspond  to 
the  apex  of  the  ventricle. 

The  best  method  of  opening  the  left  ventricle  consists  in  making  a  vertical  section 
through  the  septum ;  but  in  doing  this,  the  right  ventricle  must  be  sacrificed. 

In  order  to  obtain  a  general  view  of  the  appearance  of  these  cavities,  they  may  be  pre- 
pared in  the  dried  state.  For  this  purpose,  the  heart  is  to  be  injected  with  tallow,  and 
then,  after  being  dried  sufficiently,  to  be  opened  in  the  manner  above  described,  and  im- 
mersed in  warm  turpentine,  which  will  dissolve  the  tallow,and  leave  the  ventricles  dilated. 

Interior  of  the  Right  Ventricle. 

The  right  ventricle  occupies  the  right  anterior  and  inferior  portion  of  the  heart,  and  has, 
therefore,  been  called  the  anterior  or  the  inferior  Fig.  193. 

ventricle.  Its  cavity  (Jig.  193)  has  a  three-sided 
pyrjunidal  form.  Its  inner  wall  (6)  is  convex,  and 
is  formed  by  the  septum  of  the  ventricles  ;  in  its 
lower  half  it  has  a  well-marked  reticulated  appear- 
ance, which  is  almost  entirely  absent  in  the  upper 
half  (a).  The  anterior  and  inferior  walls  (partly  re- 
moved in^.  193)  are  both  concave,  and  are  re- 
markable for  their  thinness,  so  that  they  are  al- 
ways collapsed  when  the  ventricle  is  empty.  The 
base  of  this  ventricle  presents  two  openings,  which 
are  separated  from  each  other  by  a  projecting  part, 
and  which  may  be  compared  to  the  wide  circular 
end,  and  the  narrow  mouthpiece  of  a  huntsman's 
horn.  The  opening  into  the  auricle  (in  which  a 
bristle  is  placed)  corresponds  to  the  wide  end  of 
the  horn,  and  the  infundibulum  (a)  to  the  narrower 
end.  The  transverse  diameter  of  the  base  of  this 
ventricle  is  nearly  equal  to  its  height.  The  sum- 
rait  (Z)  is  turned  towards  the  apex  of  the  heart. 

The  walls  of  the  right  ventricle  are  very  remark- 
able for  their  reticulated  or  areolar  character ;  this 
areolar  portion  might  be  termed  the  corpus  cavernosum  of  the  heart,  for  it  presents  the 
spongy  structure  of  the  erectile  tissues.  The  fleshy  columns  which  form  the  areolae  are 
observed  not  only  upon  each  of  the  walls  of  the  ventricle,  but  they  also  pass  across  the 
cavity  of  the  ventricle  near  its  summit,  extending  from  one  wall  to  the  other ;  in  conse- 
quence of  which  the  capacity  of  the  ventricle  is  singularly  diminished. 

The  cylindrical  fleshy  columns  {columnce  carnece,  teretes  lacerti),  which  separate  the 
meshes  or  areolae,  are  of  three  kinds.  Some  (c)  are  attached  to  the  parietes  of  the  heart 
by  one  of  their  extremities,  and  are  free  in  the  rest  of  their  extent ;  they  terminate  by  a 
kind  of  simple  or  double  meimmillated  projection,  from  which  proceed  small  tendinous 
cords  {chorda  tendinem),  that  are  inserted  into  the  auriculo-ventricular  valves  (c).  They 
are  very  few  in  number,  and  have  been  named  the  muscles  of  the  heart  {musculi  papillares). 
The  fleshy  columns  of  the  second  kind  are  free  throughout  the  whole  of  their  extent,  ex- 
cepting at  their  extremities,  which  are  attached  to  the  walls  of  the  ventricle.  These  col- 
umns, which  are  the  most  numerous,  are  divided  and  subdivided  to  form  the  areolae.  The 
third  kind  of  columnae  carneae  adhere  to  the  walls  of  the  ventricle  by  one  of  their  sides  ; 
they  are  therefore  sculptured  like  pilasters  upon  the  walls  of  the  ventricle. 

Most  of  the  colmnnae  carneae  pass  from  the  apex  towards  the  base  of  the  heart.  In 
all  their  free  portion,  the  columns  of  the  two  first  kinds  are  attached  to  each  other  or  to 
the  walls  of  the  ventricle,  by  means  of  small  tendinous  cords,  which  are  much  more  deli- 
cate than  those  proceeding  to  the  valves.  The  areolar  muscular  structure  just  described 
is  the  essential  constituent  of  the  walls  of  the  ventricle  ;  but  in  addition  to  it  there  is  a 
rather  thin,  compact,  and  non-reticulated  layer  of  superficial  fibres,  on  which  depends 
the  smooth  appearance  of  the  external  surface  of  the  ventricle. 

The  Orifices  of  the  Right  Ventricle. — At  the  base  of  the  right  ventricle  there  are  two 
orifices,  one  auricular,  which  establishes  a  communication  between  the  ventricle  and  the 


ANGEIOLOGY. 


auricle  ;  the  other  arterial,  which  leads  into  the  pulmonary  artery.    They  are  both  fur- 
nished with  valves. 

The  right  auricular  or  auriculo-ventricular  orifice  (through  which  the  bristle  is  inserted, 
Fig.  194.  fig.  193)  is  placed  at  the  posterior  and  right  part  of  the  base  of 

the  ventricle ;  it  is  elliptical,  and  is  provided  with  a  mem- 
branous structure,  called  the  tricuspid  or  triglochin  valve  (c), 
which  projects  into  the  interior  of  the  ventricle.     This  valve 
is  of  an  annular  form  (annulus  valvulosus).    Its  ventricular  sur- 
face {t  1 1,  fig.  194)  is  directed  towards  the  parietes  of  the  ven- 
tricle, and  receives  a  great  number  of  small  tendinous  cords, 
which,  being  attached  to  it  at  different  points,  give  it  an  ir- 
^  regular  aspect.     Its  auricular  surface  {t  t  t,fig.  195),  which  is 
turned  towards  the  axis  of  the  ventricle,  is  smooth.     The  ad- 
herent border  is  fixed  to  the  margin  of  the  auricular  orifice. 
The  free  border  or  margin  forms  a  ring,  the  diameter  of  which  is  equal  to  that  of  the 
.gg  adherent  border :  this  margin  is  irregularly  divided,  so  that,  in- 

''^'      ■  stead  of  the  three  segments  {t  1 1)  generally  described,  and  from 

which  the  name  of  the  valve  has  been  derived  {rpelc,  tres,  three, 
and  y^uxk,  cuspis,  a  point),  some  authors  admit  four,  or  even 
six  segments. 

The  construction  of  the  tricuspid  valve  can  be  understood 
only  by  regarding  it  as  composed  of  two  parts,  an  anterior,  cor- 
responding to  the  anterior  half  of  the  elliptical  auriculo-ventric- 
ular orifice,  and  a  posterior,  corresponding  to  the  posterior 
half  of  the  same.  The  tricuspid  valve  is  not  unfrequently  in- 
terrupted on  the  left  side  opposite  the  junction  of  these  two 
valves.  This  valve  might,  with  as  much  propriety,  be  termed  mitral,  as  that  which  is 
attached  to  the  lefl  auriculo-ventricular  opening. 

To  the  free  margin  of  the  valve,  upon  which  some  small  nodules  are  occasionally 
found,  are  attached  a  number  of  tendinous  cords  of  a  nacreous  aspect,  which  are  ex- 
tremely strong  considering  their  tenuity.  These  small  cords,  or,  rather,  tendinous  fila- 
ments, always  arise  in  greater  or  less  number  from  the  summits  of  the  columnae  car- 
nese ;  diverging  from  thence,  often  bifurcating  during  their  course,  and  sometimes  be- 
coming united  together,  they  terminate,  some  at  the  free  margin,  others  at  the  ventric- 
ular surface  of  the  valve,  and  others,  again,  at  its  adherent  border. 

All  the  smalll  tendinous  cords  do  not  arise  from  the  columnae  cameas  of  the  first  kind  ; 
many  of  them  proceed  directly  from  the  parietes  of  the  heart.  We  constantly  find  a 
fasciculus  of  diverging  cords  arising  from  the  septum. 

These  cords  are  so  arranged,  that,  by  drawing  upon  them,  the  valve  is  depressed  and 
stretched.  We  find,  in  fact,  that  both  in  the  anterior  and  posterior  part  of  the  tricuspid 
valve,  those  cords  which  arise  from  the  free  margin  on  one  side  converge  towards  those 
of  the  opposite  side,  some  even  crossing  each  other  in  the  form  of  the  letter  X. 

The  arterial  or  pulmonary  orifice  {ostium  arteriosum,  d,fig.  194)  is  placed  at  the  anterior 


Fig.  196. 


part  of  the  left  side  of  the  base  of  the  right  ventricle.  It  is  sep- 
arated from  the  auricular  orifice  by  a  tolerably  prominent  mus- 
cular band,  which  is  concave  on  its  lower  surface,  and  divides 
the  right  ventricle  into  two  portions,  an  auricular  and  a  puhno- 
nary  portion  or  infundibulum.  This  orifice  is  circular,  and  is 
provided  with  three  very  distinct  valves,  which  are  named  sig- 
moid or  semilunar  {f,fig.  195  ;  a  a  a,  fig.  196).*  Although  thin 
and  semi-transparent,  they  are  very  strong.  They  are  directed 
vertically  as  the  blood  is  passing  from  the  ventricle  into  the 
artery,  and  become  horizontal  when  it  tends  to  flow  back  from 
the  artery  into  the  ventricle.  Of  their  two  surfaces,  the  ven- 
tricular corresponds  to  the  .cavity  of  the  ventricle  ;  the  other,  or 
arterial  surface,  includes  between  it  and  the  walls  of  the  artery 
a  small  cul-de-sac,  which  has  been  compared  to  a  pigeon's  nest. 
The  adherent  border  of  each  valve  is  convex,  and  directed  to- 
wards the  ventricle ;  its  free  margin  presents  in  the  middle  a 
small  nodule,  by  which  it  is  divided  into  two  semilunar  halves. 
When  depressed,  the  valves  completely  close  the  vessel,  the 
three  nodules  filling  up  the  triangular  interval  left  between  the  approximated  free  mar- 
gins. These  valves  must,  therefore,  oppose  the  reflux  of  the  blood  into  the  ventricle  ; 
but  the  resistance  offered  by  them  is  easily  overcome  by  an  injection  thrown  into  the 
pulmonary  artery. 

Interior  of  the  Left  Ventricle. 
The  left  ventricle  occupies  the  left  upper  and  back  part  of  the  heart ;  it  is  evidently 

*  It  is  extremely  rare  to  find  any  anomaly  in  the  number  of  these  valves,  either  by  an  increase  or  a  dinu 
BUtion  of  them. 


THE   HEART.  485 

constructed  upon  the  same  fundamental  type  as  the  right  ventricle,  but  difFers  from  il 
in  many  respects,  as  we  shall  now  proceed  to  show. 

Difference  in  Situation. — The  different  positions  of  the  two  ventricles  are  sufficient- 
ly known  from  what  has  already  been  stated ;  but  it  is  important  to  remark,  that  the 
left  ventricle  projects  beyond  the  other  at  the  apex  of  the  heart  {fig.  197),  while  the 
right  is  more  prominent  at  the  base,  in  consequence  of  the  existence  of  the  infundibulum. 

Difference  in  Shape. — The  right  ventricle  is  pyramidal,  and  becomes  collapsed  when 
not  distended ;  the  left  is  conical  and  convex,  not  only  on  its  free  surface  (6),  but  even 
at  the  septum  (a,  fig.  194),  where  it  seems  to  project  into  the  interior  of  the  right  ven- 
tricle. 

Difference  in  Size. — It  is  generally  stated,  in  accordance  with  Senac,  Winslow,  and 
Haller,  that  the  right  ventricle  is  more  capacious  than  the  left  :  this  statement  is  found- 
ed upon  direct  observation,  which  proves  that  the  right  ventricle  gains  more  at  the  base 
than  the  left  does  at  the  apex ;  also  upon  deductions  made  by  comparing  the  right  auri- 
cle and  the  pulmonary  artery  with  the  left  auricle  and  the  aorta  ;  and,  lastly,  upon  the 
results  obtained  by  injecting  the  cavities  of  the  heart.  No  two  observers  agree  as  to 
the  exact  numbers  which  would  represent  the  capacities  of  the  two  ventricles,  as  the 
following  different  estimates  will  show.  The  capacity  of  the  left  ventricle  to  that  of  the 
right  has  been  stated  as  31  to  33,  as  10  to  11,  as  5  to  6,  as  2  to  3,  and  as  1  to  2. — {Hol- 
ler, t.  i.,  1.  iv.,  sect.  3,  p.  327  ) 

Now  the  discrepancies  in  these  estimates  prove  either  the  deficiency  of  the  methods 
of  observation,  or  the  existence  of  real  differences  resulting  from  a  greater  or  less  amount 
of  accidental  obstruction  to  the  pulmonary  circulation  occurring  shortly  before  death. 
In  the  great  majority  of  subjects,  the  right  ventricle  is  proved  to  be  more  capacious  than 
the  left,  and  this,  according  to  the  judicious  remark  of  Sabatier,  depends  upon  the  state 
of  the  circulation  through  the  heart  during  the  last  moments  of  life,  at  which  time  the 
blood  flows  back  from  the  lungs  into  the  right  ventricle,  while  the  left  ventricle,  not  ex- 
periencing a  similar  obstruction,  and,  moreover,  acting  with  greater  vigour,  empties  it- 
self, more  or  less  completely,  of  the  blood  contained  within  it.  After  death  by  decapita- 
tion, the  right  ventricle  is  as  much  contracted  as  the  left ;  also,  in  individuals  that 
have  died  without  any  agony  or  exhaustion,  the  cavity  of  the  left  ventricle  has  been  com- 
pletely contracted.* 

The  condition  of  the  heart,  then,  in  the  dead  body,  in  which  that  organ  is  found  as  it 
was  at  the  moment  of  death,  affords  us  no  means  of  judging  of  the  relative  capacity  of 
its  cavities  during  life.  If,  by  tying  the  aorta  in  a  living  animal,  we  cause  stagnation  of 
the  blood  in  the  left  ventricle,  while  the  exit  of  that  fluid  from  the  right  cavities  through 
the  pulmonary  artery  remains  unimpeded,  the  relative  capacity  of  the  two  ventricles  will 
be  found  to  be  exactly  the  reverse  of  what  is  generally  indicated. 

The  gradual  injection  of  the  heart  with  wax  or  tallow,  so  as  to  distend  the  ventricles 
without  producing  laceration,  enables  us  to  determine  the  size  and  the  weight  of  the 
mass  of  injection  contained  within  each  cavity  of  the  heart,  and  also  to  measure  these 
cavities  under  similar  conditions,  that  is  to  say,  in  a  state  of  distension.  From  obser- 
vations which  I  have  made  in  this  way,  it  appeared  that  the  left  ventricle  was  rather 
more  capacious  than  the  right. 

Difference  in  the  Appearance  of  the  Cavity  and  in  the  Structure  of  its  Parietes. — In  the 
left  ventricle  we  find  the  three  kinds  of  columnas  carneae.  Of 
the  columns  of  the  first  kind  there  are  only  two  (i  i,fig.  197), 
which  are  remarkable  for  their  great  size.  Their  summits  are 
almost  always  bifurcated,  and  sometimes  they  are  divided  into 
three  parts  ;  not  unfrequently  each  of  these  columnae  results 
from  the  apposition  of  two  or  three  others,  which  are  united 
by  small  fibrous  cords  or  filaments. 

The  fleshy  columns  of  the  second  kind  are  smaller  in  the 
left  than  in  the  right  ventricle.  The  areolar  arrangement  is 
less  strongly  marked,  and  is  observed  only  in  the  innermost 
layer,  excepting  always  at  the  apex,  the  whole  thickness  of 
which,  with  the  exception  of  the  most  superficial  layer,  pre- 
sents the  cavernous  arrangement.  Moreover,  the  areolae  are 
remarkable  for  their  small  size,  and  for  the  slenderness  and 
jiumber  of  the  columnae  by  which  they  are  surrounded.  These 
muscular  areolae  are  often  completed  by  fibrous  cords. 

Difference  in  Thickness. — The  walls  of  the  left  ventricle  are 
much  thicker  than  those  of  the  right  {figs.  193,  194,  197).  The  proportion  of  one  to  two, 
arrived  at  by  Laennec#is  too  slight ;  it  is  one  to  four,  or  even  one  to  five.  It  is  gener- 
ally said  that  the  muscular  tissue  of  the  heart  is  more  compact  on  the  left  than  on  the 
right  side. 

*  The  concentric  hypertrophy  mentioned  by  authors  appears  to  apply  to  ordinary  hearts,  or  to  hearts  in  « 
state  of  hypertrophy,  with  their  cavities  closed,  in  conseqaence  of  the  eontraction  continuing  to  the  last  mo- 
ment.    I,  therefore,  am  opposed  to  admitting  concentric  liypertrophy  as  a  pathologioal  state. 


486  ANGEIOLOGY. 

Difference  in  the  Orifices. — The  left  auriculo-ventricular  orifice  (through  which  a  bristle 
is  inserted,  ^o'.  197)  exactly  resembles  the  right  one,  and,  like  it,  is  provided  with  a 
valve  {g)  analogous  to  the  tricuspid,  and  named  by  Vesalius  the  mitral  valve,  from  its 
being  regularly  divided  into  two  opposite  segments  {mm,  figs.  194,  195).  The  mitral 
valve  is  stronger  than  the  tricuspid,  it  is  thick<|-  and  longer,  and  receives  stronger  and 
more  numerous  chordae  tendineae.  These  differences  are  more  particularly  observed  in 
the  right  segment  of  the  mitral  valve,  which  projects,  like  an  incomplete  septum,  into 
the  cavity  of  the  ventricle,  and  appears  to  divide  it  into  an  aortic  and  an  auricular  por- 
tion ;  the  left  segment  of  the  valve  {g,fig.  196),  on  the  contrary,  is  applied  against  the 
walls  of  the  ventricle. 

The  aortic  orifice  {e,fig.  194)  exactly  resembles  the  pulmonary  orifice  of  the  right  ven- 
tricle ;  like  that  opening,  it  is  also  provided  with  three  sigmoid  valves  (e,  fig.  195),  which 
differ  from  those  of  the  pulmonary  artery  merely  in  being  stronger,  and  in  having  larger 
nodules  or  globules  upon  their  free  borders  ;  and,  as  Arantius  admitted  their  existence 
only  in  these  valves,  they  are  therefore  called  globuli,  noduli  or  corpora  Arantii.* 

The  right  auriculo-ventricular  and  arterial  orifices  are  placed  at  a"  distance  from  each 
other,  but  the  corresponding  orifices  of  the  left  side  are  contiguous,  so  that  the  adherent 
border  of  the  right  half  of  the  mitral  valve  is  continuous  with  the  adherent  border  of  the 
corresponding  sigmoid  valve ;  and  hence  it  follows,  that  when  these  valves  are  removed, 
the  base  of  the  ventricle  presents  only  one  orifice. 

Interior  of  the  Jiuricles. 

Dissection  of  the  Right  Auricle. — Make  a  horizontal  incision  from  the  auricula  to  the 
inferior  vena  cava,  and  then  a  vertical  one  from  the  vena  cava  superior  perpendicularly 
to  the  first. 

Of  the  Left  Auricle. — ^Make  a  vertical  incision  from  before  backward,  between  the 
right  and  left  pulmonary  veins,  including  the  entire  posterior  wall  of  the  auricle.  In  or- 
der to  have  an  accurate  idea  of  the  shape  of  the  interior  of  the  auricles,  inject  a  heart 
with  tallow  or  wax,  and  then  examine  the  cast  thus  taken  of  their  cavities. 

Interior  of  the  Right  Auricle. 

The  shape  of  the  right  auricle,  when  distended,  may  be  compared  to  the  segment  of 
an  irregular  oval,  the  long  diameter  of  which  is  directed  from  before  backward.  It  has 
three  walls :  an  anterior,  which  is  convex ;  an  internal,  which  is  slightly  concave,  and 
corresponds  to  the  septum ;  and  a  posterior,  also  concave,  which  forms  the  greatest  part 
of  the  auricle,  and  is  remarkable  for  the  existence  upon  it  of  fleshy  columns.  The  right 
auricle  has  four  orifices. in  the  adult,  and  five  in  the  foetus,  viz.,  the  auriculo-ventricular 
orifice,  the  opening  of  the  vena  cava  superior,  that  of  the  vena  cava  inferior,  that  of  the 
coronary  vein,  and,  in  the  foetus,  the  foramen  ovale  (trou  de  Botal),  the  situation  of  which 
is  occupied  in  the  adult  by  the  fossa  ovalis. 

The  auriculo-ventricular  wifice  {see  fig.  195),  the  largest  of  all,  is  of  an  elliptical  form, 
from  sixteen  to  eighteen  lines  in  its  longest  diameter,  which  is  from  before  backward, 
and  about  twelve  lines  in  its  shortest  diameter.  It  is  surrounded  by  a  whitish  zone 
(a  q),  to  which  is  attached  the  adherent  border  of  the  tricuspid  valve  {t  1 1).  The  cavity 
of  the  auricle  presents  a  sort  of  constriction  opposite  the  auriculo-ventricular  orifice. 

The  orifi.ce  {h,fig.  193)  of  the  vena  cava  superior  {d)  is  circular,  and  is  directed  down- 
ward and  a  little  backward  ;  it  has  no  valves  ;  it  is  bounded  on  the  left  by  a  projecting 
muscular  band,  which  separates  it  from  the  auricle,  and  on  the  right  by  a  less  prominent 
band  intervening  between  it  and  the  vena  cava  inferior.  The  former  of  these  two  bands, 
which  are  distinctly  marked  upon  the  cast  of  wax,  separates  the  fasciculated  portion  of 
the  auricle  from  the  non-fasciculated  portion,  which  seems  to  be  formed  by  an  expansion 
of  the  venae  cavae. 

The  orifice  (?)  of  the  vena  cava  inferior  (r)  opens  into  the  auricle,  near  the  septum,  not 
perpendicularly  upward,  but  horizontally,  and  at  right  angles  to  the  original  direction  of 
the  vein,  which  is  vertical.  The  orifice  is  circular,  and  larger  than  that  of  the  superior 
cava ;  the  inferior  cava  sometimes  forms  an  ampulla  or  dilatation  before  it  enters  the 
auricle  ;  us  orince,  unlike  that  of  the  superior  cava,  is  provided  with  a  remarkable  semi- 
lunar valve,  the  valvula  Eustachii  (n),  which  surrounds  the  anterior  half,  and  sometimes 
two  thirds  of  this  opening.  Its  free  margin  is  concave,  and  directed  upward  ;  its  adhe- 
rent border  is  convex,  and  directed  downward  :  one  of  its  surfaces  is  turned  forward  to- 
wards ihe  auricle,  the  other  backward  towards  the  vessel ;  one  of  its  extremities  ap- 
pears to  be  continuous  with  the  margin  of  the  fossa  ovalis  (*),  and  the  other  is  lost  upon 
the  margin  of  the  opening  of  the  inferior  cava. 

The  valve  of  Eustachius  closes  the  orifice  of  that  vein  very  imperfectly.  In  its  upper 
two  thirds  it  is  extremely  thin,  and  resembles  the  valves  of  the  veins  ;  its  lower  third 
contains  a  muscular  fasciculus. 

*  The  three  sigmoid  valves  of  the  aorta  are  generally  very  similar  in  form  ;  in  one  case,  however,  which  I 
examined,  one  of  these  valves  had  twice  the  size  of  the  others.  I  have  lately  observed,  in  a  man  of  sixty,  who 
died  of  a  disease  of  the  heart,  the  rare  sight  of  an  aorta  provided  with  only  two  sigmoid  valves ;  these  two 
mlves  were  very  large,  and  ia  relation  with  the  diameter  of  the  aortic  orifice,  which  they  covered  completely 


THE  HEART.  487 

The  orifice  of  the  coronary  vein  is  placed  immediately  in  front  of  the  preceding,  from 
which  it  is  separated  by  the  Eustachian  valve.  It  is  sometimes  situated  at  the  bottom 
of  a  small  cavity  or  vestibule.  It  is  provided  with  a  very  thin  semilunar  valve  {valvula 
Thebesii,  below  and  behind  the  bristle),  which  exactly  resembles  the  valves  of  the  veins, 
and  completely  covers  the  mouth  of  the  vessel.  The  upper  extremity  of  this  valve  is 
continuous  with  the  lower  end  of  the  Eustachian  valve. 

The  Inter-auricular  Orifice. — In  the  foetus,  the  inter-auricular  septum  is  perforated  be- 
hind and  below  by  an  opening  improperly  called  the  foramen  of  Botal,  for  it  was  known  to 
Galen,  who  described  a  free  communication  between  the  auricles.  After  birth,  we  find 
in  the  situation  of  the  foramen  ovale  a  fossa  {fossa  ovalis,  vestigium  foramims  ovalis),  or, 
rather,  a  plane  surface,  which  is  generally  smooth,  but  occasionally  uneven,  and,  as  it 
were,  reticulated  ;  it  is  bounded  in  front  and  above  by  a  semicircular  ridge  or  border  (s), 
which  is  improperly  called  the  isthmus  or  annulusVieussenii,  and  may  be  regarded  as  a  more 
or  less  perfect  sphincter.  Behind,  the  fossa  ovalis  is  continuous  with  the  vena  cava  in- 
ferior ;  the  semicircular  ridge  or  border  of  the  fossa  ovalis  is  formed  by  a  curved  mus- 
cular fasciculus,  sometimes  very  thick,  the  concavity  of  which  is  directed  backward ; 
the  inferior  extremity  of  the  fasciculus  is  continuous  with  the  Eustachian  valve. 

The  fossa  ovalis  is  frequently  found  to  be  prolonged  beneath  the  semicircular  border 
or  annulus,  so  as  to  form  a  sort  of  cul-de-sac,  the  bottom  of  which  is  often  perforated, 
and  the  handle  of  a  scalpel  may  not  unfrequently  be  introduced  through  this  opening 
into  the  left  auricle,  although  no  morbid  phenomenon  may  have  been  observed  during 
life. 

The  Fasciculated  and  Reticulated  Portion  of  the  Auricle. — Upon  the  internal  surface  of 
the  auricle,  to  the  right  of  the  vena  cava,  are  observed  certain  muscular  fasciculi  or 
fleshy  columns  (musculi  pectinati  auricula,),  which  are  directed  vertically  from  the  auric- 
ula towards  the  auriculo-ventricular  orifice.  These  fasciculi  adhere  to  the  auricle  on 
one  side  only  ;  they  are  intersected  by  other  oblique  and  smaller  bundles,  which  give  a 
reticulated  aspect  to  the  inner  surface  of  the  auricle. 

Cavity  of  the  Auricula. — The  auricula,  or  that  portion  of  the  auricle  which  extends 
from  the  vena  cava  superior  to  the  bottom  of  the  appendix,  consists  of  an  areolar  or  cav- 
ernous structure,  exactly  resembling  that  which  has  been  described  in  the  ventricles. 
The  same  cavernous  structure  is  found  in  other  parts  of  the  auricle,  and  in  particulai 
near  the  orifice  of  the  coronary  vein. 

I  agree  with  Haller*  and  Boyer,  in  denying  the  existence  of  the  tubercle  of  Lower, 
described  by  that  anatomist  as  situated  (at  m)  between  the  openings  of  the  venae  cavse. 

It  is  generally  admitted  that  a  certain  number  of  small  veins  open  into  the  right  auri- 
cle by  minute  orifices  without  valves.  We  find,  in  fact,  some  openings  resembling  vas- 
cular orifices,  and  known  under  the  name  of  the  foramina  Thebesii ;  they  are  constantly 
found  below  the  orifice  of  the  vena  cava  superior,  but  most  of  them  only  lead  into  small 
groups  of  areolae,  and  injections  do  not  demonstrate  the  existence  of  any  corresponding 
vessels.    The  only  true  vascular  orifices  are  those  for  the  anterior  coronary  veins. 

Interior  of  the  Left  Auricle. 

The  cavity  of  the  left  auricle  (fig.  197)  differs  from  that  of  the  right  in  the  following 
circumstances  :  in  being  less  capacious  than  the  right  auricle,  the  proportion  between 
them  being  four  to  five  ;  in  its  form,  which  is  irregularly  cuboid ;  in  the  number  of  its 
orifices,  of  which  there  are  five  after  birth,  and  six  in  the  fcetus ;  in  the  character  of 
those  orifices  :  thus  the  left  auriculo-ventricular  orifice  (see  fig.  195)  is  smaller  than  the 
right ;  its  long  diameter,  which  is  transverse,  is  from  thirteen  to  fourteen  lines,  its  short 
diameter  is  from  nine  to  ten  lines ;  the  four  other  openings  belong  to  the  pulmonary  veins, 
two  (c)  on  the  right,  and  two  (c  c)  on  the  left  side,  and  all  are  without  valves  ;t  in  the 
structure  of  its  auricula,  which  is  perfectly  distinct  from  the  rest  of  the  auricle,  and  con- 
tains a  central  conical  cavity,  leading  into  the  auricle  by  a  well-defined  circular  open- 
ing ;  in  the  left  auricle,  nothing  is  seen  on  the  septum  corresponding  to  the  fossa  ovalis,t 
at  least  we  perceive  neither  band  nor  ring  by  which  it  is  circumscribed.  When  the  two 
auricles  communicate  by  an  oblique  passage,  we  find  a  very  thin  fibrous  band,  beneath 
which  the  scalpel  may  be  introduced  into  the  right  auricle. 

Structure  op  the  Heart. 

The  heart  is  essentially  a  muscular  organ,  and  has  a  framework  consisting  of  certain 
fibrous  rings  or  zones  ;  it  is  covered  by  a  layer  of  serous  membrane ;  the  left  cavities 
are  lined  by  a  membrane  continuous  with  the  internal  coat  of  the  arteries,  and  the  right 

*  "  Id  tuberculum  cupide  receptum  est,  ut  fere  fit,  ab  iis  scriptoribug  quibus  occasio  ad  propria  experimenta 
nulla  est,deinde  etiam  abiis  qui  tandem  omnin(Jiu  corporibus  humanis  dissecandis  se  exercuerunt." — (Ualler 
Elem.  Phys.,  t.  i.,  lib.  iv.,  sect.  2,  p.  314.) 

t  It  is  not  uncommon  to  meet  with  five  openings,  three  on  the  right  and  two  on  the  left  side  ;  in  other  cases, 
the  two  left  pulmonary  veins  open  by  a  common  orifice. 

t  [The  situation  of  the  foetal  opening  {a.  Jig.  197)  is  very  commonly  indicated  by  a  recess  of  variable  depth 
opening  between  the  left  surface  of  the  septum  and  the  (still  free)  crescentic  border  ofhbe  valve  of  the  fora- 
men ovale.] 


488  ANGEIOLOGY. 

cavities  by  one  continuous  with  the  lining  membrane  of  the  veins.*     Some  nerves,  prop- 
er vessels,  and  cellular  tissue,  also  enter  into  its  structure. 

The  Framework  of  the  Heart. 

This  term  may  be  applied  to  foxxx  fibrous  zones  (the  tendinous  circles  of  Lower),  which 
may  be  regarded  as  affording  both  origin  and  insertion  to  all  the  muscular  fibres  of  the 
heart.  These  zones  are  situated  at  the  four  orifices  of  the  ventricles,  viz.,  the  two  au- 
riculo-ventricular  and  the  two  arterial  orifices. 

Dissection. — Remove  with  care  the  adipose  tissue,  and  the  vessels  which  occupy  the 
furrows  of  the  heart.  Examine  the  fibrous  zones  from  the  internal  surface  of  the  heart 
In  order  to  study  the  relations  of  the  orifices  with  each  other,  remove  the  auricles,  the 
aorta,  and  the  pulmonary  artery,  a  little  above  those  orifices. 

The  Auriculo-ventricular  Zones. — Each  auriculo-ventricular  zone  is  a  tolerably  regular 
fibrous  circle,  which  surrounds  the  opening  between  the  auricle  and  ventricle,  and  de- 
termines its  form  and  dimensions.  These  fibrous  circles  give  off  expansions  of  a  sim- 
ilar nature,  which  enter  into  the  formation  of  the  tricuspid  and  mitral  valves,  and  thus 
add  to  their  strength.  The  chordae  tendineae  of  the  heart  also  terminate  in  these  zones, 
either  directly  or  through  the  medium  of  the  valves. 

The  left  auriculo-ventricular  zone  is  stronger  than  the  right. 

The  Arterial  Zones. — These  are  two  circular  rings,  the  diameter  of  each  of  which  is 
somewhat  less  than  that  of  its  corresponding  artery,  so  that  there  are  some  very  distinct 
folds  or  wrinkles  produced.  These  two  zones  are  exactly  alike  in  form,  but  differ  some- 
what in  strength,  the  aortic  being  stronger  than  the  pulmonary.  From  these  zones  are 
given  off  three  very  thin  but  very  strong  prolongations,  which  occupy  the  angular  inter- 
vals formed  by  the  indented  border  by  which  the  aorta  and  pulmonary  artery  commence  ; 
and  three  other  prolongations  extend  into  the  substance  of  the  sigmoid  valves.  These 
prolongations  form  very  distinct  fibrous  bundles  in  the  sigmoid  valve  of  the  aorta.t 

Relative  Position  of  t'he  Orifices  of  the  Ventricles  (see  fig.  195). — The  two  auriculo-ven- 
tricular orifices  are  situated  upon  the  same  plane,  posterior  to  the  other  orifices,  and  ap- 
proach each  other  at  their  middle. 

The  long  diameters  of  these  two  orifices  are  at  right  angles  to  each  other  :  thus,  the 
long  diameter  of  the  right  auriculo-ventricular  orifice  is  directed  from  before  backward, 
while  that  of  the  left  orifice  is  directed  transversely. 

In  the  angular  interval  left  between  these  two  orifices  in  front,  the  aortic  opening  (f) 
is  closely  united  to  them  both  ;  so  that  the  posterior  half  of  the  circumference  of  the  aor- 
tic zone  is  blended  with  both  auriculo-ventricular  zones.  At  the  point  of  junction  be- 
tween them,  we  find  a  cartilaginous,  and  in  the  larger  animals  a  bony,  arch,  which  was 
described  by  the  ancients  under  the  name  of  the  bone  of  the  heart :  in  this  situation,  also, 
we  frequently  find  the  ossiform  concretions  of  the  orifices. 

Lastly,  upon  a  plane  in  front  and  on  the  left  of  the  aortic  opening,  and  about  five  or 
six  lines  above  it,  is  situated  the  orifice  (/)  of  the  pulmonary  artery. 

The  orifice  of  the  aorta  is  directed  towards  the  right  side,  that  of  the  pulmonary  ai- 
tery  towards  the  left,  so  that  these  two  vessels  cross  each  other,  so  as  to  represent  the 
letter  X.  It  follows,  therefore,  that  the  pulmonary  orifice  is  separated  from  the  right 
auriculo-ventricular  opening  by  the  orifice  of  the  aor  a. 

In  examining  these  openings,  we  observe  that  the  plane  of  the  auriculo-ventricular  or- 
ifices is  directed  obliquely  backward  and  downward  :  this  explains  the  difference  in  the 
heights  of  the  ventricles  before  and  behind.  We  also  notice  the  reflection  or  turning  in- 
ward of  the  base  of  each  ventricle  (q  a,  p  b)  upon  itself,  so  as  to  form  a  circular  groove 
or  trench  on  the  inner  surface  of  its  cavity,  running  entirely  round  the  margin  of  the  cor- 
responding auriculo-ventricular  orifice. 

The  Muscular  Fibres  of  the  Heart. 

The  Muscular  Fibres  of  the  Ventricles. 

Dissection. — The  muscular  fibres  of  the  heart  may  sometimes  be  traced  without  any 

preparation  ;  but,  generally  speaking,  either  commencing  putrefaction,  maceration  in 

vinegar,  or,  still  better,  hardening  and  separation  of  the  fibres  by  means  of  alcohol,  and 

especially  by  boiling,  are  necessary  for  this  purpose.     This  being  done,  remove  first  the 

*  [The  muscular  fibres  of  the  heart,  though  involuntary,  very  closely  resemble  in  structure  those  of  the 
voluntary  muscles  (see  note,  p.  194),  but  the  transverse  striae  upon  them  are  less  distinct. 

The  lining  membranes  of  the  two  sides  of  the  heart  are  covered  by  epithelium,  and  form  what  is  termed 
the  endocardium.']  , 

t  I  for  a  long  time  believed  that  the  sigmoid  valves,  both  the  aortic  and  the  pulmonary,  were  formed  by 
two  prolongations  of  the  internal  membrane  of  the  heart  reflected  upon  itself ;  but  I  have  from  pathological 
facts  lately  the  positive  demonstration  that  each  sigmoid  valve  was  formed,  1st,  by  a  prolongation  of  the  in- 
ternal membrane  of  the  aorta ;  2d,  by  a  prolongation  of  the  internal  membrane  of  the  ventricle  ;  3d,  by  an  in- 
termediate lamella  occupying  only  the  half  of  the  height  of  the  valve  on  the  side  of  its  adhering  borde.i ;  this 
lamella  is  fibrous,  and  comes  from  the  arterial  zone.  The  half  of  the  valve  which  is  near  the  free  border  is 
not  furnished  with  this  intermediate  lamella.  Now  the  arterial  lamella  may  be  affected  independently  of  the 
ventricular,  and  both  Ijie  arterial  and  ventricular  lamellis  may  be  injured  independently  of  the  intermediate 
fibrous  lamella  which  constitutes  the  foundation  of  these  valves,  since  it  gives  them  chiefly  their  power  of  re- 
sistance. 


THE   HEART.  489 

oater  membrane,  and  then  the  different  muscular  layers  one  by  one,  taking  care  to  fol- 
low the  fibres  from  their  origin  to  their  termination. 

The  most  general  formula  which  can  be  given  respecting  the  structure  of  the  ventri- 
cles is,  that  this  portion  of  the  heart  is  composed  of  two  muscular  sacs,  co7itained  within  a 
third,  which  is  commjon  to  both  ventricles.  We  should  add,  that,  when  the  superficial  or 
common  fibres  arrive  at  the  apex  of  the  heart,  they  turn  up  so  as  to  pass  into  the  interi- 
or of  the  ventricles  at  that  point,  and  form  the  deep  fibres  of  these  two  cavities,  so  that 
the  proper  fibres  of  each  ventricle  are  situated  between  the  direct  and  the  reflected  por- 
tion of  the  common  fibres. 

We  shall  now  enter  into  some  details  regarding  these  fibres. 

All  the  muscular  fibres  arise  from  the  fibrous  zones,  and  they  all  terminate  upon  them, 
as  was  clearly  pointed  out  by  Lower.*  They  do  not  consist  of  short  fibres  placed  end 
to  end,  but  are  of  considerable  length,  descending  in  one  part  of  their  course,  and  as- 
cending in  the  other.  The  muscular  fibres  are  ranged  in  successive  layers,  which  pass, 
as  it  were,  into  each  other.  The  muscular  fasciculi  of  each  layer  are  not  distinct  from 
one  another,  but  they  mutually  send  off  fibres,  by  which  they  are  bound  together  like  the 
pillars  of  the  diaphragm ;  or  it  may  be  said  that  they  intersect  each  other  at  very  acute 
angles ;  it  is,  therefore,  impossible  to  calculate  the  number  of  layers,  which,  according 
to  Wolff,  are  about  three  in  the  right  ventricle  and  six  in  the  left.  All  that  we  are  able 
to  determine  is,  the  different  sets  of  fibres  which  enter  into  the  formation  of  the  heart, 
and  of  these  we  find  that  there  are  two  sets,  one  common,  the  other  _pro^er  fibres. 

The  Superficial  Common  Fibres. — All  the  superficial  fibres  are  common  to  the  two  ven- 
tncles,  and  all  are  oblique  and  curved ;  they  commence  at  the  base  of  the  heart,  and 
pass  obliquely,  in  a  spiral  manner,  towards  the  apex.  All  the  superficial  fibres  of  the  an- 
terior region  of  the  heart  pass  from  the  right  to  the  left  side  ;  all  those  of  the  posterior 
region  from  the  left  to  the  right  side.  There  are  neither  vertical  nor  horizontal  fibres  in 
the  heart,  as  some  authors  have  stated.  The  arrangement  of  the  fibres  at  the  apex  of 
the  heart  forms,  as  it  were,  a  key  to  the  stnicture  of  the  entire  organ.  The  anterior 
and  the  posterior  superficial  common  fibres  both  converge  towards  that  point.  Each  of 
these  sets  of  fibres  forms  a  very  distinct  fasciculus  or  band,  and  the  two  bands  mutually 
turn  round  each  other  in  a  semi-spiral  direction,  so  that  the  anterior  band  is  embraced 
on  the  left  side  by  the  posterior,  which  is,  in  its  turn,  embraced  by  the  anterior  band  on 
the  right  side  ;  from  the  apex  of  the  heart  the  fibres  change  their  course,  and  instead 
of  descending,  they  ascend  ;  and  instead  of  being  superficial,  they  become  deep-seated. 
Having  entered  the  heart  at  its  apex,  they  continue  to  be  reflected  upward,  and  present  an 
arrangement  which  I  shall  describe  after  having  explained  the  course  of  the  proper  fibres. 

The  Proper  Fibres. — ^These  are  situated  between  the  superficial  or  descending,  and  the 
deep  or  ascending  portion  of  the  common  fibres.  They  form  in  each  ventricle  a  sort  of 
small  barrel  or  truncated  cone,  which  is  applied  to  that  of  the  opposite  ventricle  ;  the  su- 
perior openings  of  these  cones  correspond  to  the  auriculo- ventricular  orifices  ;  while  the 
inferior,  which  are  smaller,  leave  opposite  the  apex  of  the  heart  two  considerable  inter- 
vals, which  are  filled  up  by  the  common  fibres.  Do  these  proper  fibres  turn  round  and 
round  without  end,  hke  an  uninterrupted  spiral,  as  Senac  was  inclined  to  believe  1  It 
appears  to  me  that  their  extremities  are  attached  to  the  auriculo-ventricular  zones,  and 
that  they  describe  more  or  less  complete  circles,  which  intersect  each  other  at  very 
acute  angles. 

The  Reflected  or  Deep  Common  Fibres. — The  superficial  common  fibres  are  reflected  at 
the  apex  of  the  heart,  and  penetrate  into  its  interior  through  the  lower  orifices  of  the 
small  barrels  or  cones,  formed  by  the  proper  fibres.  In  this  situation  the  anterior  and 
posterior  bands,  by  being  reflected  upward,  and  mutually  turned  round  each  other,  form, 
at  the  apex  of  the  heart,  a  sort  of  star  with  curved  rays. 

Nothing  can  be  more  evident  than  the  reflection  or  turning  up  of  the  fibres  ;  it  was 
pointed  out,  thougn  vaguely,  by  Vesalius,  but  has  been  most  explicitly  described  by  Ste- 
no,  who  stated  expressly  that  the  external  fibres  enter  the  heart  at  the  apex,  and,  assu- 
ming an  opposite  direction  to  their  former  one,  become  the  innermost  layers,  and  who 
compared  the  apex  of  the  heart  to  a  star.  It  was  also  described  by  Lower,  who  has  ac- 
curately figured  a  radiated  structure  at  the  summit  of  each  ventricle  ;  by  Winslow,  who 
says  that  the  superficial  fibres  enter  the  heart  at  its  apex ;  and  by  Wolff  and  Gerdy,  who 
state  that  the  fibres  of  the  heart  are  twisted  into  a  whorl  or  vortex. 

From  the  turning  back  and  the  lateral  twisting  of  the  anterior  and  posterior  bands,  it 
follows  that,  by  removing  the  serous  membrane  which  covers  the  apex  of  the  heart,  we 
may,  without  injuring  the  fibres,  penetrate  into  its  interior  at  two  points,  one  to  the 
right,  and  the  other  to  the  left  of  the  anterior  band. 

The  deep  reflected  fibres  having  thus  reached  the  interior  of  the  ventricles,  pass  on 
the  inner  side  of  the  proper  fibres,  and  are  arranged  in  three  perfectly  different  modes  : 
thus,  some  form  simple  loops  with  the  superficial  portion  ;  others  are  arranged  like  the 
thread  of  a  screw,  or  the  figure  8.  and  others  constitute  the  columnae  carneae. 

*  The  same  arTangement  occurs  in  regard  to  the  fibres  of  the  auricles  ;  it  follows,  therefore,  that  the  nxii» 
cular  fibres  of  the  ventricles  are  not  directly  continuous  with  those  of  the  auricles. 

Qqq 


490  ANGEIOLOGY. 

The  looped  fibres,  noticed  by  Winslow  under  the  name  of  the  bent  or  arched  fibres,  and 
so  well  described  by  Gerdy,  form,  by  their  superficial  and  their  deep  portions,  the  opposite 
walls  of  the  ventricle  :  thus,  the  anterior  superficial  fibres  constitute  by  their  reflection 
the  deep  layer  of  the  posterior  wall,  while  the  posterior  superficial  fibres,  after  being  re- 
flected, form  the  deep  layer  of  the  anterior  waU. 

The  fibres,  arranged  like  the  thread  of  a  screw,  or  like  the  figure  8,  with  its  lower  ring  ex- 
tremely narrow,  have  been  accurately  described  and  even  figured  by  Lower,  and  were 
improperly  rejected  by  Winslow,  Senac,  and  others.  The  superficial  portion  of  these 
fibres  exactly  resembles  that  of  the  looped  fibres,  and  are  always  twisted  after  their  re- 
flection, so  that  their  deep  portion  belongs  to  the  same  wall  as  their  superficial.  Thus, 
those  fibres  whose  superficial  portion  belongs  to  the  anterior  wall  of  the  ventricle,  assist 
in  forming  the  same  wall  by  their  deep  portion. 

The  columnce,  carnea  of  the  heart  are  formed  by  a  certain  number  of  fibres  reflected  in 
loops,  or  like  the  figure  8. 

Such  is  the  arrangement  of  the  muscular  fibres  of  the  ventricles.* 

The  Muscular  Fibres  of  the  Auricles. 

The  auricles,  like  the  ventricles,  have  common  and  proper  muscular  fibres.  There  is  only 
one  fasciculus  of  common  fibres  ;  it  occupies  the  anterior  surface  of  both  auricles,  and 
extends  transversely  from  the  right  to  the  left  auricula.  The  proper  fibres  constitute  a 
very  thia  muscular  layer  for  each  auricle ;  they  all  commence  and  terminate  at  the  cor- 
responding ventricular  zone. 

The  Proper  Fibres  of  the  Left  Auricle. — The  muscular  layer  in  this  auricle  is  continuous 
and  uniform,  and  not  areolar.  It  consists  of  circular  fibres,  which  occupy  the  neighbour- 
hood of  the  auriculo- ventricular  orifice,  and  all  the  anterior  region  of  the  auricle  ;  and  of 
oblique  fibres,  also  arising  from  the  auriculo-ventricular  orifice,  and  divided  into  several 
very  distinct  loops.  One  circular  loop  passes  between  the  auricula  and  the  left  pulmo- 
nary veins  ;  a  second  forms  a  vertical  zone,  interposed  between  the  right  and  left  pulmo- 
nary veins  ;  it  is  very  broad,  and  occupies  the  entire  interval  between  the  veins  of  the 
right  and  left  side  ;  a  third  and  a  fourth,  very  small,  are  interposed  between  the  two  pul- 
monary veins  of  each  side.  These  fasciculi,  by  changes  in  their  direction,  become  adapt- 
ed to  the  circular  form  of  the  orifices,  and  constitute  true  sphincters.  It  would  appear 
that,  besides  these  bundles,  there  are  some  proper  circular  fibres  around  each  orifice. 

The  Proper  Fibres  of  the  Right  Auricle. — In  the  right  auricle  the  fleshy  fibres  do  not 
form  a  continuous  layer.  This  auricle  may  be  regarded  as  consisting,  in  the  first  place, 
of  a  non-muscular  portion,  which  may  be  called  the  confluence  of  the  vence  cavce  {sinus  ve- 
nosus) ;  in  it  there  is  only  one  small  muscular  bundle,  situated  immediately  to  the  right 
of  the  orifice  of  the  vena  cava  superior ;  and,  secondly,  of  a  muscular  portion,  which  re- 
sembles a  sort  of  grating,  and  is  comprised  between  two  fasciculi,  one  a  circular  bun- 
dle, surrounding  the  auriculo-ventricular  orifice  ;  the  other  a  very  prominent  semilunar 
bundle,  interposed  between  the  vena  cava  inferior  and  the  auricula,  and  forming  a  ver- 
tical, or,  rather,  an  oblique  arch,  which  terminates  to  the  right  of  the  inferior  cava. 

Muscular  Fibres  of  the  Auricula. — The  walls  of  the  left  auricula  present  a  cavernous 
or  areolar  structure,  in  the  middle  of  which  we  see  a  central  canal,  which  opens  into  the 
anterior  of  the  auricle  by  a  distinct  orifice.  There  is  not,  in  general,  any  central  canal  in 
the  right  auricula,  but  only  an  areolar  or  cavernous  structure. 

The  muscular  fibres  of  the  inter-auricular  septum  form  a  muscular  ring  for  the  border 
of  the  fossa  ovalis  (so  incorrectly  termed  the  isthmus  or  annulus  of  Vieussens),  which 
must  be  regarded  as  a  true  sphincter,  consisting  of  two  thirds,  three  fourths,  or  even  an 
entire  circle.  The  fibres  of  which  it  is  formed  arise  from  the  auriculo-ventricular  ori- 
fice, near  the  septum.  Some  muscular  fibres  are  often  found  in  the  substance  of  the  floor 
of  the  fossa  ovalis.  The  other  muscular  fibres  of  the  septum  are  continuous  with  the 
circular  fibres  of  the  auricles. 

Separation  of  the  Two  Hearts. 

Dissection. — Divide  the  anterior  fibres  of  the  ventricles  carefully,  layer  by  layer,  paral- 
lel to  the  anterior  furrow.  Then  separate  the  two  ventricles,  by  means  of  the  finger  or 
the  handle  of  the  scalpel.  In  order  to  separate  the  auricles,  carry  the  scalpel  along  the 
posterior  inter-auricular  furrow,  being  particularly  careful  upon  arriving  at  the  fossa  ova- 
lis. It  is  often  possible  to  separate  the  auricles  completely  without  opening  either  of  them. 

The  division  of  the  heart  into  the  right  and  the  left  heart  is  not  merely  imaginary  or 
theoretical,  but  is  capable  of  actual  demonstration.  After  making  the  beautiful  prepara- 
tion described  above,  we  find  that  the  left  convex  ventricle  is  received  into  a  correspond- 
ing concavity  in  the  right  ventricle ;  the  two  are  therefore  adapted  to  each  other,  and 

*  The  arrangement  described  above  is  common  to  both  ventricles.  In  the  ri^ht  ventricle  almost  all  the  re- 
flected fibres  enter  into  the  columnve  cameae.  There  is  no  interlacing,  or  indigitation  of  the  fleshy  fibres  along 
the  anterior  and  posterior  furrows,  as  has  been  stated  ;  still  less  do  we  find  a  raph6  in  the  situation  of  these 
furrows.  The  splitting  and  separation  of  the  muscular  fibres,  caused  by  the  entrance  of  the  bloodvessels  oppo- 
site the  furrows,  and  the  condensation  of  the  fibres  between  the  openings  for  the  vessels,  have  occasioned  thes« 
•rroneous  views. 


THE   HEART.  4#1 

their  mutual  reception  is  rendered  complete  by  means  of  the  infiindibuliform  prolonga- 
tion of  the  right  ventricle. 

On  the  other  hand,  the  right  auricle  is  convex,  and  is  received  into  a  corresponding 
concavity  in  the  left  auricle. 

By  placing  the  two  halves  of  the  heart  together,  we  see  clearly  the  position  of  the  aor- 
tic opening  behind  and  to  the  right  side  of  the  pulmonary,  the  crossing  of  the  aorta  and 
the  pulmonary  artery  in  the  form  of  the  letter  X ;  the  relation  of  the  aorta  with  the  base 
of  the  right  ventricle,  and  its  situation  between  the  right  auriculo-ventricular  orifice, 
which  is  behind,  and  the  infundibuliform  prolongation  of  the  right  ventricle,  which  is  in 
front  of  it.  This  last  relation  explains  how  a  communication  may  take  place  between 
the  aorta  and  the  right  ventricle. 

The  separation  of  the  two  sides  of  the  heart  also  enables  us  to  judge  accurately  of  the 
shape  and  the  relative  size  of  the  two  ventricles,  the  regular  conical  form  of  the  left 
ventricle,  and  the  prismatic  and  triangular  form  of  the  right  ventricle,  the  left  wall  of 
which  is,  as  it  were,  pushed  inward  by  the  corresponding  projection  of  the  left  ventricle. 
We  can  also  ascertain  the  shape  and  relative  size  of  the  two  auricles. 

Vessels,  JVerves,  and  Cellular  Tissue. 

Arteries. — The  heart  receives  certain  proper  arteries,  called  cardiac  or  coronary,  from 
their  being  arranged  in  the  form  of  a  circle  or  crown.  They  are  two  in  number,  and  are 
the  first  branches  given  off  by  the  aorta.  They  form  two  arterial  circles  placed  at  right 
angles  to  each  other ;  that  is  to  say,  one  circle  follows  the  auriculo-ventricular  furrow, 
and  the  other  occupies  the  inter- ventricular  furrow. 

Veins. — Corresponding  to  these  two  arteries  there  is  one  vein,  named  the  great  car- 
diac or  coronary  vein,  and  a  few  small  ones,  called  the  anterior  coronary  veins.  I  do  not 
think  that  the  existence  of  those  accessory  veins  described  by  Thebesius  as  terminating 
directly  in  the  right  auricle  and  the  other  cavities  of  the  heart  has  been  clearly  demon- 
strated. I  have  already  said  that  the  common  openings  of  several  groups  of  areolae  have 
been  often  mistaken  for  the  orifices  of  veins.  There  is  always  an  opening  resembling 
the  orifice  of  a  vein  below  the  vena  cava  superior,  but  injection  does  not  show  any  ves- 
sel there. 

Lymphatics. — These  terminate  in  the  numerous  lymphatic  glands  which  surround  the 
bronchi  and  the  lower  part  of  the  trachea. 

Nerves. — The  cardiac  nerves  are  small  when  compared  with  the  nerves  received  by 
other  muscular  organs,  with  those  of  the  tongue,  for  example,  and  especially  with  those 
of  the  muscles  of  the  orbit.  Some  are  derived  from  the  cervical  ganglia  of  the  sympa- 
thetic nerves,  the  others  from  the  cerebro-spinal  system,  viz.,  the  cardiac  branches  of 
the  pneumogastric. 

These  nerves,  which  are  placed  near  the  arteries,  follow  them  at  first,  but  soon  sep- 
arate from  them,  and  are  lost  in  the  muscular  substance.  We  cannot,  therefore,  admit 
the  opinion  of  Behrends,  who  attempted  to  prove  that  the  nerves  are  intended  only  for 
the  vessels  of  the  heart,  and  not  for  its  proper  tissue. 

Cellular  Tissue. — The  serous  cellular  tissue  which  unites  the  muscular  fasciculi  of  the 
heart  is  so  delicate,  that  it  is  extremely  difficult  to  demonstrate  it.  In  certain  cases  of 
disease  it  may  become  loaded  with  fat.  • 

We  always  find  a  greater  or  less  amount  of  fat  upon  the  surface  of  the  heart  beneath 
the  serous  membrane  ;  it  abounds  in  the  circular  furrow  between  the  auricles  and  ven- 
tricles, in  the  furrow  of  the  ventricles,  at  the  apex  and  right  border  of  the  heart,  in  the 
furrow  between  the  pulmonary  artery  and  the  aorta,  and  between  the  small  digital  ap- 
pendages upon  the  top  of  the  left  auricle. 

'  Development. 

In  Size. — The  heart  is  larger  in  proportion  to  the  rest  of  the  body  in  the  earlier  stages 
of  its  development. 

In  the  foetus,  at  the  full  term  and  after  birth,  the  weight  of  the  heart  is  to  that  of  the 
body  as  1  to  120  ;  before  the  end  of  the  third  month  of  intra-uterine  life  it  is  as  1  to  50. 
It  should  be  renoembered  that,  at  the  fourth  or  fifth  week,  the  heart  of  the  foetus  occu- 
pies the  entire  cavity  of  the  thorax.  In  old  age,  the  heart  does  not  undergo  atrophy  like 
most  of  the  other  organs ;  and,  in  many  subjects  far  advanced  in  years,  it  is  even  hyper- 
trophied. 

In  Direction. — During  the  first  three  months  the  heart  of  the  foetus  is  directed  verti- 
cally, as  in  other  mammalia ;  it  does  not  begin  to  deviate  to  the  left  side  and  forward,  as 
in  the  adult,  until  the  fourth  month. 

In  Shape.* — The  heart,  at  an  early  period,  forms  a  rounded  and  symmetrical  mass,  of 
which  the  auricles  constitute  the  greatest  part ;  the  ventricles  appear  at  this  time  to  be 
only  appendages  of  the  heart,  and  the  right  auricle  alone  is  equal  in  size  to  all  the  rest 
of  the  organ.  The  ventricles  are  gradually  enlarged,  while  the  auricles  diminish,  and 
towards  the  fifth  month  the  due  proportion  between  the  auricles  and  ventricles  is  estab- 

■  "^  ^  *  See  note,  p.  492. 


4^  ANGEIOLOGY. 

lished ;  the  left  ventricle  is,  at  this  period,  more  capacious  than  the  right.  The  walls  of 
the  heart  are  thicker  than  they  are  afterward,  and  the  heart  is  firmer,  and  does  not  col- 
lapse when  empty.   The  thickness  of  the  parietes  of  both  ventricles  is  almost  the  same. 

In  Interned  Conformation. — It  is  in  reference  to  its  internal  structure  that  the  principal 
changes  occur  during  the  development  of  the  heart.  The  right  and  left  sides  of  the 
heart  communicate  freely  during  the  whole  period  of  intra-uterine  existence.  The  in- 
ter-auricular septum  does  not  exist,  or,  at  least,  only  in  a  rudimentary  state,  during  the 
earlier  months  of  foetal  life. 

Is  there  any  period  of  fcetal  existence  during  which  the  inter- ventricular  septum  is 
entirely  wanting  1  and  does  the  development  of  the  human  heart,  which  would  then  re- 
semble the  heart  of  reptiles,  coincide  with  the  general  law  by  which  the  organs  of  man, 
before  acquiring  their  perfect  form,  pass  successively  through  the  several  conditions  rep- 
resented by  the  corresponding  organs  in  the  lower  animals'!  The  observations  of  Meck- 
el, which  extend  as  far  back  as  the  fourth  week,  prove  that  the  inter-ventricular  septum 
always  exists  at  that  period,  but  that  it  is  imperfect  at  the  upper  part,  where  it  is  perfo 
rated  or  notched.* 

Cases  of  malformation,  in  which  the  septum  of  the  ventricles  is  absent,  cannot  be  quo 
ted  in  support  of  the  opinion  that  the  septum  is  wanting  in  the  early  periods  of  life  ;  foi 
it  would  be  necessary  to  prove  that  such  a  malformation  is  an  arrest  of  development. 

The  opening  between  the  two  auricles  becomes  contracted,  and  forms  the  foramen 
ovale  (or  foramen  ofBotal),  which  is  found  at  the  posterior  and  inferior  part  of  the  septum. 

The  valve  of  Eustachius  is  sufficiently  broad  to  separate  the  orifice  of  the  vena  cava 
inferior  from  the  cavity  of  the  right  auricle,  so  that  the  blood  of  that  vein  is  carried  di- 
rectly into  the  left  auricle. 

Towards  the  end  of  the  third  month,  the  valve  of  the  foramen  ovale,  which  afterward 
forms  the  bottom  of  the  fossa  ovalis,  begins  to  appear  ;  it  arises  from  the  posterior  half 
of  the  opening  of  the  vena  cava  inferior.  About  the  same  period  the  Eustachian  valve 
decreases  in  size,  and  from  this  time  the  development  of  these  two  valves  proceeds  in- 
versely, that  is  to  say,  the  Eustachian  valve  diminishes,  while  that  of  the  foramen  ovale 
becomes  larger.  In  consequence  of  this  change,  the  vena  cava  inferior  no  longer  opens 
into  the  left  auricle,  but  into  the  right. 

At  the  fifth  month  the  foramen  ovale  is  almost  entirely  closed  by  the  valve  which 
grows  from  below  upward,  and  from  behind  forward ;  at  a  later  period  it  projects  into 
the  left  auricle,  beyond  the  margin  of  the  foramen  ovale,  so  that  there  is  an  oblique  pas- 
sage from  one  auricle  to  the  other.  After  birth,  adhesion  takes  place  between  these 
parts  ;  but  even  when  this  does  not  occur,  the  obliquity  of  the  passage  is  such,  that  the 
want  of  adhesion  does  not  necessarily  allow  of  any  admixture  of  the  blood  of  the  two 
auricles. 

Function. 

The  heart  is  the  agent  by  which  the  blood  is  impelled  tlirough  the  vessels.  The  ve- 
nous blood  is  poured  into  the  auricles,  which  then  contract ;  part  of  the  blood  flows  back 
into  the  veins,  but  the  greater  portion  passes  into  the  ventricles,  which  contract  in  their 
turn.  The  auriculo- ventricular  valves  meet,  and  prevent  the  reflux  of  the  blood  into  the 
auricles,  and  it  is,  therefore,  propelled  intg  the  arteries.  The  sigmoid  valves  at  first  lie 
in  contact  with  the  walls  of  the  arteries,  so  as  to  permit  the  blood  to  pass  from  the  ven- 
tricles ;  they  then  fall  down  at  the  moment  when  the  distended  arteries  react  upon  their 
contents,  and  thus  prevent  the  reflux  of  the  blood  into  the  ventricles.  The  contraction 
and  dilatation  of  the  heart  have  been  termed  its  systole  and  its  diastole. 

The  two  auricles  contract  simultaneously ;  so  also  do  the  two  ventricles.  The  dila- 
tation of  the  auricles  occurs  during  the  contraction  of  the  ventricles,  and  vice  versa. 
Dilatation  is  not  an  active  phenomenon,  for  the  fibres  of  the  heart  are  so  arranged  that 
they  can  produce  shortening  and  contraction  of  this  organ,  but  can  neither  elongate  nor 
dilate  it. 

The  spiral  direction  of  the  fibres  of  the  heart  induced  the  ancients  to  conjecture  that 
the  contractions  of  the  ventricles  took  place  in  a  spiral  fashion  ;  and,  in  the  first  edition 
of  this  work,  looking  only  at  the  anatomical  arrangement,  I  said  that  this  view  of  the 
subject  was  not  so  devoid  of  foundation  as  at  first  sight  it  might  be  imagined.    But, 

*  [The  researches  of  modern  emhryologists  have  shown  that  the  heart,  in  its  simplest  condition,  consists  of 
a  straight  tube,  which  is  placed  vertically  in  the  body,  receives  the  veins  at  its  inferior  extremity,  and  gives 
off  the  arteries  from  its  superior  extremity.  The  lower  or  venous  end  soon  turns  upward,  so  that  the  tube  be- 
comes bent  into  a  loop,  which  for  a  time  projects  through  a  cleft  on  the  anterior  aspect  of  the  body.  The  tube 
then  becomes  divided  into  an  auricular  and  a  ventricular  portion,  and  into  a  bulbus  arteriosus,  all  enclosed  in 
a  pericardium;  and  in  this  state  the  heart  of  the  human  ftstus  corresponds  with  the  permanent  condition  of 
this  organ  in  fishes.  Each  of  these  three  portions  becomes  again  subdivided  :  the  auricular  portion  by  a  de- 
scending septum  into  the  two  auricles,  the  ventricular  by  an  ascending  septum  into  the  two  ventricles,  and 
the  bulbus  arteriosus  into  the  aorta  and  pulmonary  artery.  For  a  certain  period,  the  right  and  left  auricles 
and  the  right  and  left  ventricles  communicate  with  each  other.  When  the  septum  between  the  ventricles  ii 
yet  imperfect  (a  condition  which  is  permanent  in  reptiles  generally),  the  common  ventricular  cavity  gives  ori- 
gin to  both  the  aorta  and  the  pulmonary  artery.  Before  the  middle  of  fcetal  life  this  septum  is  completed,  and 
then  the  two  vessels  arise  each  separately  from  its  proper  ventricle.  The  septum  between  the  auricles  re- 
mains imperfect  until  after  birth,  when  the  foramen  ovale  at  length  becomes  closed.] 


THE   HEART. 

from  the  opportunities  I  have  lately  had  of  observing  the  movements  of  the  heart  in  a 
new-born  child,  full  of  life  and  vigour,  whose  heart,  deprived  of  the  pericardium,  had 
passed  entirely  outside  of  the  chest,  through  a  circular  perforation  in  the  upper  part  of 
the  sternum,  I  have  been  enabled  to  establish  the  following  facts  in  reference  to  this  in- 
teresting subject  (see  Gazette  de  Paris,  August  7th,  1841) : 

First,  the  contraction  of  the  right  ventricle  and  the  contraction  of  the  left  ventricle 
are  simultaneous,  or  synchronous  ;  this  is  also  the  case  with  the  contraction  of  the  au- 
ricles. 

Second,  the  contraction  of  the  ventricles  coincides  with  the  dilatation  of  the  auricles 
and  the  projection  of  the  blood  into  the  arteries.  The  dilatation  of  the  ventricles  coin- 
cides with  the  contraction  of  the  auricles  and  that  of  the  arteries. 

Third,  there  are  but  two  conditions  in  the  movements  of  the  heart :  those  of  its  con- 
tractions and  those  of  its  dilatations  ;  the  state  of  rest  which  is  spoken  of  by  authors  is 
completely  wanting.  Dilatation  is  immediately  followed  by  contraction,  and  contraction 
by  dilatation. 

Fourth,  in  observing  the  heart  in  the  case  referred  to,  the  question  about  the  order  of 
succession  in  the  movements  of  the  heart,  viz.,  whether  the  contraction  of  the  auricles 
precedes  that  of  the  ventricles,  as  most  observers  assert,  or  whether  the  contraction  of 
the  ventricles  precedes  that  of  the  auricles,  is  found  to  have  no  foundation  to  rest  on : 
it  seems  that  the  contraction  and  the  dilatation  of  the  ventricles  and  that  of  the  auricles 
result  from  two  opposite  forces,  continually  active,  which  alternately,  and,  as  it  were, 
necessarily  conquer  each  other  in  an  invariable  order,  in  the  fashion  of  the  two  alternate 
movements  of  a  pendulum,  or  a  perfectly-balanced  balance-pole. 

Fifth,  the  duration  of  the  contraction  of  the  ventricles  continues  twice  as  long  as  that 
of  their  dilatation.  On  dividing  into  three  equal  periods  the  whole  duration  of  the  sys- 
tole and  diastole  of  the  ventricles,  we  will  have  two  for  the  contraction  and  one  for  the 
dilatation.  The  period  of  repose  mentioned  by  authors  has  been  taken  from  the  first 
period  of  the  contraction.  In  regard  to  the  auricles,  on  dividing  into  three  equal  parts 
the  whole  duration  of  their  contraction  and  dilatation,  we  wiU  have  two  for  dilatation 
and  one  for  contraction. 

Sixth,  during  the  time  of  their  contraction  or  systole,  the  ventricles  grow  pale,  their 
surface  becomes  rugged,  strongly  folded,  and,  as  it  were,  shrivelled.  The  superficial 
veins  swell ;  the  columnse  carneae  of  the  ventricles  are  marked  off;  the  twisted  fibres 
of  the  summit  of  the  left  ventricle,  which  of  itself  constitutes  the  apex  of  the  heart,  be- 
come more  manifest. 

Seventh,  during  their  contraction  the  ventricles  contract  in  all  their  diameters ;  and 
if  the  phenomenon  of  their  shortening  is  the  most  sensible,  this  is  attributable  to  the 
greater  dimension  of  the  vertical  diameter.  During  the  systole  of  the  ventricles,  the 
summit  of  the  left  ventricle,  or,  what  is  the  same,  the  summit  of  the  heart,  describes  a 
spiral  movement  from  right  to  left  and  from  behind  forward. 

Eighth,  it  is  this  spiral  contraction,  which  is  slow,  gradual,  and  successive,  as  it 
were,  which  produces  the  movement  forward  of  the  summit  of  the  heart,  and,  conse- 
quently, the  striking  of  the  apex  against  the  walls  of  the  thorax.  The  systole  of  the 
ventricles  is  not  accompanied,  as  I  had  before  beheved,  with  a  movement  of  projection 
of  the  heart  forward  :  it  is  the  spiral  contraction  which  determines  exclusively  the  ap- 
proximation to,  and  even  the  striking  of  the  apex  of  the  heart  against  the  walls  of  the 
thorax. 

Ninth,  the  dilatation  or  diastole  of  the  ventricles  takes  place  in  a  sudden,  instanta- 
neous manner :  at  first  sight  one  would  say  that  it  constituted  the  active  movement  of 
the  heart,  it  is  so  rapid  and  energetic.  No  one  can  have  any  idea,  without  having  ex- 
perienced it,  of  the  force  with  which  the  dilatation  overcomes  pressure  made  upon  this 
organ.    The  hand  which  firmly  grasps  the  heart  is  forcibly  opened  by  its  diastole. 

Tenth,  the  dilatation  or  diastole  of  the  ventricles  is  accompanied  with  a  movement 
of  projection  of  the  heart  downward.  This  movement  of  projection  was  carried  to  its 
maximum  when  the  child  was  placed  in  the  vertical  position ;  it  was  so  marked,  that  at 
first  I  was  induced  to  believe  that  it  was  during  the  diastole  of  the  ventricles  that  the 
percussion  of  the  heart  against  the  walls  of  the  thorax  took  place.  This  idea  I  still  en- 
tertained, rom  an  experiment  which  I  had  made  at  a  former  period  upon  the  hearts  of 
frogs  ;  but  a  more  accurate  examination  of  the  phenomenon  has  shown  me  that  it  was, 
indeed,  during  the  systole  of  the  ventricles,  and  towards  the  end  of  this  systole,  that  the 
percussion  of  the  apex  of  the  heart  against  the  walls  of  the  thorax  took  place. 

Eleventh,  the  dilatation  of  the  auricles  takes  place  as  suddenly  as  the  dilatation  of  the 
ventricles,  but  it  lasts  as  long  as  the  systole  of  the  ventricles  :  the  contraction  of  the  auri- 
cles, on  the  contrary,  lasts  no  longer  than  the  diastole  of  the  ventricles. 

Twelfth,  during  its  dilatation,  the  right  auricle  seems  on  the  point  of  bursting,  so 
great  is  its  distension  and  so  thin  are  its  walls.  The  left  auricle,  which  is  narrower, 
more  elongated,  and  thicker,  does  not  exhibit  the  same  phenomenon,  at  least  not  in  the 
same  degree.  I  have  not  been  able  to  judge  of  what  takes  place  in  the  auricular  pro- 
cesses except  from  the  movements  of  the  auricles. 


494  ANGEIOLOGY. 

In  regard  to  the  sounds  of  the  heart,  it  results,  from  the  experiments  which  I  have 
made  upon  the  heart  of  this  child  {Medical  Gazette,  loco  citato),  that  the  two  sounds  of 
the  heart  have  their  seat  at  the  origin  of  the  pulmonary  and  aortic  arteries,  and  that 
they  originate  in  the  clashing  of  the  sigmoid  valves  ;  that  the  first  sound,  which  coin- 
cides with  the  systole  of  the  ventricles  and  the  dilatation  of  the  arteries,  results  from 
the  rising  of  the  sigmoid  valves,  which  were  previously  lowered ;  that  the  second  sound, 
which  coincides  with  the  diastole  of  the  ventricles  and  with  the  contraction  of  the  ar- 
teries, results  from  the  lowering  of  the  sigmoid  valves  pressed  down  again  by  the  gush 
of  the  returning  blood.  The  simplicity  of  this  theory,  the  easy  and  natureil  explanation 
which  it  affords  of  all  the  facts  that  have  come  to  my  knowledge,  may,  perhaps,  be  con- 
sidered as  a  proof  of  its  truth. 


THE  PERICARDIUM. 

The  pericardium  {pp,fig-  170)  is  a  fibro-serous  sac,  which  surrounds  and  protects  the 
heart. 

Congenital  absence  of  the  pericardium  is  extremely  rare  ;  complete  adhesion  of  the 
pericardium  to  the  heart,  or  cellular  transformation  of  this  membrane,  have  been  most 
commonly  mistaken  for  such  malformation.  Nevertheless,  I  have  seen  the  heart  of  an 
adult  to  which  there  was  no  pericardium :  this  anomaly  has  been  figured  by  M.  Breschet. 
The  heart  was  free  from  any  adhesion,  and  occupied  the  cavity  of  the  left  pleura. 

The  older  anatomists,  and  particularly  Senac,  attempted  to  determine  exactly  how 
much  larger  the  cavity  of  the  pericardium  is  than  the  heart.  Having  injected  water  into 
the  pericardium  in  different  subjects,  this  observer  found  that  the  quantity  of  liquid  con- 
tained between  the  heart  and  its  covering  varied  from  six  to  twenty-four  ounces.  I  have 
satisfied  myself  that  in  the  healthy  state,  the  capacity  of  the  pericardium  exactly  corre- 
sponds to  the  size  of  the  heart  when  that  organ  is  dilated  to  the  utmost.  In  certain 
cases  of  hydrops  pericardii,  this  sac  becomes  enormously  enlarged ;  on  the  other  hand, 
its  inextensibility  explains  the  syncope  which  immediately  follows  rupture  of  the  heart,* 
and  which  is  produced  by  the  accumulation  of  a  small  quantity  of  blood  in  the  pericar- 
dium. The  syncope  which  accompanies  the  effusion  from  acute  pericarditis  probably 
depends  upon  a  similar  cause. 

Form. — The  pericardium  is  shaped  like  a  cone,  with  its  base  downward  and  its  apex 
upward.     It  has  an  external  and  an  internal  surface. 

External  Surface. — The  pericardium  is  situated  in  the  mediastinum,  and  has  the  fol- 
lowing relations : 

In  front  it  corresponds  to  the  sternum  and  the  cartilages  of  the  fifth,  sixth,  and  seventh 
ribs  on  the  left  side,  from  which  it  is  separated  by  the  pleura  and  the  lungs ;  in  the  mid- 
dle it  is  separated  from  the  sternum  by  some  cellular  tissue  only.  The  pericardium  is 
in  more  or  less  immediate  relation  with  the  sternum,  according  to  the  size  of  the  heart, 
or  the  quantity  of  fluid  in  the  pericardium.  Behind,  it  corresponds  to  the  vertebral  col- 
umn, from  which  it  is  separated  by  the  posterior  mediastinum  and  the  organs  contained 
in  it,  viz.,  the  oesophagus,  the  aorta,  the  thoracic  duct,  &c.  On  the  sides,  it  is  in  imme- 
diate relation  with  the  pleurae,  and  indirectly  with  the  lungs.  The  phrenic  nerves  and 
the  superior  phrenic  arteries  are  applied  along  the  sides  of  the  pericardium.  The  base 
corresponds  to  the  cordiform  tendon  of  the  diaphragm,  and  to  the  muscular  fibres  on  the 
left  side  of  it.  It  adheres  closely  to  the  diaphragm  only  in  the  anterior  half  of  its  cir- 
cumference ;  in  every  other  part  the  base  of  the  pericardium  may  be  easily  detached. 
The  apex  is  prolonged  upon  the  great  vessels  which  enter  and  pass  out  at  the  base  of 
the  heart. 

The  pericardium  is  covered  by  the  pleurae  in  the  greatest  part  of  its  extent,  and  is 
united  to  them  by  cellular  tissue,  which  is  tolerably  dense  at  the  sides,  and  very  abun- 
dant in  front  and  behind.  The  cellular  tissue  of  the  anterior  mediastinum  is  often  load- 
ed with  fat,  as  well  as  that  which  surrounds  the  base  of  the  pericardium,  where  it 
sometimes  forms  prolongations  resembling  the  appendices  epiploicas  upon  the  large  in- 
testine. 

The  internal  surface  of  the  pericardiimi  is  free  and  lubricated  by  serosity,  like  the  inner 
surface  of  allfserous  cavities. t 

Structure. — The  pericardium  is  a  fibro-serous  membrane  analogous  to  the  dura  mater, 
and,  like  it,  is  composed  of  two  very  distinct  layers,  one  externd  and  fibrous,  the  other 
internal  and  serous. 

The  fibrous  layer  consists  of  fasciculi  mterlacing  in  all  directions.  It  is  extremely 
thin,  and  from  its  adhesions  to  the  cordiform  tendon  of  the  diaphragm,  it  has  been  re- 
garded as  a  prolongation  of  that  structure,  but  it  adheres  closely  to  the  diaphragm  only 

*  Death  from  rupture  of  the  heart  is  not  produced  by  hemorrhag'e,  for  often  we  do  not  find  more  than  seven 
or  eight  ounces  of  blood  escaped  ;  but  it  is  caused  by  compression  of  the  heart,  in  consequence  of  the  inexten- 
sibility of  the  pericardium. 

t  On  opening  the  thorax  of  dead  bodies,  the  internal  surface  of  the  pericardium  is,  as  it  were,  dried  up  ; 
this  drying  up  is  owing  to  the  air  contained  in  the  lungs. 


THE   ARTERIES.  495 

in  front,  and  much  less  intimately  in  the  foetus  and  the  new-bom  infant.  In  conse- 
quence of  this  adhesion,  the  pericardium  follows  all  the  motions  of  the  diaphragm. 

The  fibrous  layer  is  prolonged  upon  the  surface  of  the  great  vessels  which  open  into 
the  cavities  of  the  heart,  and  furnishes  for  each  of  them  an  indistinct  sheath,  which  is 
soon  lost  upon  them. 

The  scratis  layer  of  the  pericardium,  like  the  serous  membranes  generally,  forms  a  shut 
sac,  adherent  by  its  outer  surface,  but  free  and  smooth  internally.*  After  having  lined 
the  fibrous  layer,  it  is  reflected  upon  the  great  vessels  at  the  base  of  the  heart,  and  then 
covers  the  heart  itself,  of  which  it  forms  the  external  membrane.  We  shall  consider  it 
as  consisting  of  a  parietal,  and  a  visceral  or  reflected  portion. 

The  Parietal  Portion. — The  fibrous  and  the  serous  layer  of  the  pericardium  are  so 
closely  adherent,  that  it  is  very  difficult  to  separate  them.  We  shall  find  the  same  to  be 
the  case  with  the  dura  mater. 

The  Reflected  w  Visceral  Portion. — The  existence  of  this  portion  of  the  serous  mem- 
brane can  be  shown  most  readily  at  the  points  where  it  is  reflected  from  the  fibrous  mem- 
brane upon  the  great  vessels.  It  forms  one  complete  sheath,  which  is  coirunon  to  the 
aorta  and  pulmonary  artery ;  some  fat  is  often  found  in  the  furrow  between  these  two 
vessels  ;  it  also  forms  two  semi-sheaths  for  the  venae  cavae  and  the  four  pulmonary  veins, 
which  are  thereby  rendered  smooth  only  in  the  anterior  half  of  their  circumference.  The 
heart  is  entirely  covered  by  the  serous  membrane,  which  is  here  extremely  thin.  In  fat 
hearts  it  is  raised  from  the  muscular  fibres  by  some  flakes  of  adipose  tissue,  like  the  ap- 
pendices epiploicae  of  the  great  intestine. 

Vessels  and  Nerves. — The  arteries  of  the  pericardium  are  very  small ;  they  are  derived 
from  the  surrounding  arterial  branches,  viz.,  the  superior  phrenic,  the  anterior  mediasti- 
nal, and  the  bronchial.  The  veins  accompany  the  arteries,  and  open  into  the  brachio- 
cephalic veins.  Several  of  them  are  also  said  to  terminate  in  the  coronary  veins.  The 
lymphatic  vessels  enter  the  lymphatic  glands,  which  surround  the  vena  cava  superior. 

No  nerves  have  yet  been  demonstrated  in  the  pericardium,  though  possibly  they  may 
exist. 


THE  ARTERIES. 

Definition. — Nomenclature. — Origin. — Varieties. — Course. — Anastomoses. — Form  and  Re- 
lation.— Termination. — Structure. — Preparation. 

The  term  arteriesf  is  applied  to  the  vessels  which  arise  from  the  ventricles  of  the 
heart,  and  to  their  several  divisions. 

There  are  two  systems  of  arteries,  one  of  which  commences  at  the  right  ventricle, 
while  the  other  commences  at  the  left.  The  primitive  trunk  of  the  first  is  the  pulmona- 
ry artery,  that  of  the  second  is  the  aorta. 

These  two  arterial  systems  are  perfectly  distinct  in  the  adult,  but  communicate  fi-eely, 
and  form  only  one  system  in  the  foetus. 

The  following  general  remarks  apply  more  particularly  to  the  aorta  and  its  divisions  : 

The  arteries  form  an  uninterrupted  succession  of  decreasing  canals,  all  arising  from  a 
common  trunk.  In  this  respect  we  may  compare  the  entire  arterial  system  to  a  tree,  the 
trunk  of  which  is  the  aorta,  while  the  larger  and  smaller  branches  and  the  twigs  are  rep- 
re^sented  by  the  divisions  which  arise  in  succession  from  that  vessel,  as  from  their  com- 
mon origin. 

Again,  since  the  total  area  or  capacity  of  all  the  arterial  divisions  greatly  exceeds  that 
of  the  aorta,  we  may  also  regard  the  arterial  system  as  a  cone,  the  base  of  which  is  sit- 
uated in  the  entire  body,  and  the  apex  at  the  aorta.t 

The  study  of  the  arteries  includes  that  of  their  nomenclature,  origin,  course,  direction, 
relations,  anastomoses,  termination,  and  structure. 

Nomenclature. 

The  nomenclature  of  the  arteries  leaves  little  to  be  desired  in  regard  to  precision  ;  the 
names  of  these  vessels  are  derived  either  from  those  of  the  parts  to  which  they  are  dis- 
tributed, as  the  thyroid,  lingual,  and  pharyngeal  arteries,  &c.  ;  or  from  their  situation,  as 
the  femoral  and  radial  arteries  ;  or  from  their  direction,  as  the  circumflex  and  coronary 
arteries.  ' 

The  limits  by  which  one  artery  is  distinguished  from  another  immediately  succeeding 
to  it,  may  be  either  natural  or  artificial. 

We  may  regard  as  natural  limits  the  point  of  origin  on  the  one  hand,  the  point  of  divis- 
ion on  the  other,  as  in  the  common  iliac  and  conmion  carotid  arteries. 

*  Its  inner  surface  is  covered  with  epithelium. 

t  From  anp,  air,  and  Trjpclv,  to  keep.  The  etymology  of  this  term  affords  us  evidence  of  the  error  of  the 
ancients,  who,  because  they  always  found  these  vessels  empty  and  patent  after  death,  imagined  that  they  con- 
tained air  during  life. 

X  Haller  has  collected  all  the  comparative  estimates  that  have  been  made  between  the  area  of  the  priacipa] 
trunks  and  that  of  their  respective  divisions  collectively. — {Elem.  Phys.,  t.  i.,  p.  151-163.) 


406  ANGEIOLOGY. 

The  object  oi  artificial  limits  is  to  enable  us  to  establish  certain  divisions  of  the  same 
arterial  trunk,  by  which  means  we  can  describe  its  relations  with  greater  accuracy. 
Thus  we  shall  find  successive  portions  of  the  artery  of  the  upper  extremity  named  the 
subclavian,  the  axillary,  and  the  brachial  artery. 

Origin  of  the  Arteries. 

The  common  origin*  of  the  arterial  system  is  the  aorta,  which  arises  from  the  left  ven- 
tricle of  the  heart  in  the  manner  already  indicated  (see  The  Heart)  ;t  but  the  origins  of 
the  other  arteries  take  place  according  to  certain  very  general  laws  :  thus,  two  arteries 
of  equal  size  may  arise  from  the  extremity  of  a  larger  artery,  and  appear  to  result  from 
the  bifurcation  of  that  vessel ;  arteries  arising  in  this  manner  might  be  called  terminal 
arteries.  Other  arteries  arise  from  some  point  in  the  circumference  of  a  larger  vessel ; 
these  may  be  termed  collateral  arteries. 

The  terminal  arteries  almost  always  arise  so  as  to  form  a  bifurcation  at  an  acute  an- 
gle ;  the  dichotomous  division  or  bifurcation  is  the  most  common  mode  of  division.  The 
acute  angle  is  evidently  favourable  to  the  passage  of  the  blood,  which,  in  the  first  place, 
maintains  nearly  the  primitive  direction  in  which  it  was  impelled,  and,  secondly,  is  easi- 
ly divided  into  two  columns  by  the  projecting  crest  at  the  angle  of  division. 

The  collateral  arteries  very  often  arise  at  an  acute  angle,  but  sometimes  at  a  right,  or 
even  at  an  obtuse  angle.  The  two  latter  modes,  especially  the  last,  are  unfavourable  to 
the  flow  of  the  blood.  It  must,  however,  be  remarked,  that  many  of  the  arteries  which 
follow  a  retrograde  course  in  reference  to  the  trunk  from  which  they  are  derived,  never- 
theless arise  at  an  acute  angle.  The  caliber  of  the  terminal  arteries  is  very  nearly  pro- 
portional to  that  of  the  artery  from  which  they  are  given  oft",  but  the  collateral  arteries 
bear  no  proportion  to  the  caliber  of  their  trunks.  We  shall  see  a  remarkable  example 
of  this  in  the  spermatic  arteries,  as  compared  with  the  aorta  from  which  they  arise. 

It  should  also  be  observed,  that  the  caliber  of  a  principal  trunk  does  not  diminish  in 
proportion  to  the  branches  which  it  supplies  :  in  proof  of  this,  observe  the  aorta  as  it  en- 
ters the  abdomen,  and  just  before  its  division  into  the  common  iliac. 

Anatomical  Varieties  of  the  Arteries. 

No  system  of  organs  is  more  subject  to  anatomical  varieties  than  the  arteries.  These 
varieties  sometimes  affect  their  origin  only,  sometimes  their  course,  but  hardly  ever 
their  termination.^  The  study  of  these  varieties  is  of  great  importance  in  surgery,  both 
in  reference  to  the  ligature  of  arteries,  and  also  to  operations  performed  in  their  vicinity.^ 

Course  of  the  Arteries. 

The  principal  arteries  generally  follow  the  direction  of  the  axis  of  the  limbs.  The  sec- 
ondary, tertiary,  and  farther  divisions  pursue  the  most  varied  courses,  subject  to  no  par- 
ticular rule. 

The  principal  arteries  are  usually  straight ;  but  they  present  slight  curves,  which  ren- 
der the  artery  longer  than  the  corresponding  limb,  and  hence  tend  to  prevent  laceration 
during  the  movement  of  extension,  when  the  curves  merely  become  obliterated  and  the 
vessel  undergoes  no  injurious  stretching.  The  use  of  these  curves  in  the  arteries  may 
be  proved  by  comparing  the  opposite  conditions  of  the  vessels  during  extension  and  flex- 
ion of  the  upper  and  lower  extremities. 

A  great  number  of  the  arteries  pursue  a  very  distinctly  tortuous  course,  which,  as 
Haller  remarks,  is  preserved  by  the  surrounding  cellular  tissue,  and  which  is  connected 
with  certain  particular  conditions  of  the  organs  to  which  they  are  distributed.  Thus, 
we  meet  with  very  tortuous  arteries  in  parts  which  are  alternately  subject  to  considera- 
ble dilatation  and  contraction ;  as,  for  example,  the  coronary  arteries  of  the  heart  and 
of  the  lips. 

Again,  the  serpentine  course  of  an  artery,  by  increasing  its  length  in  a  given  space, 
adds  to  the  extent  of  surface  from  which  collateral  branches  may  arise.  The  curvatures 
of  the  internal  maxillary  and  of  the  ophthalmic  arteries  evidently  have  this  advantage  ; 
and  it  is  highly  probable  that  the  arch  of  the  aorta  may  serve  a  similar  purpose. 

The  arteries  are  tortuous  in  certain  parts  also,  in  which  this  arrangement  would  seem 
to  diminish  the  force  and  rapidity  of  the  current  of  blood ;  it  cannot  fail  to  be  perceived 

*  The  word  origin  must  not  be  taken  here  in  its  exactly  literal  sense,  for  it  has  by  no  means  been  shown  that 
the  arteries  are  developed  from  the  heart  towards  the  extremities.  A  very  ingenious  theory  tends,  on  the  con- 
trary, to  prove  that  development  proceeds  from  the  extremities  towards  the  heart. 

t  I  should  add  that  the  proper  tissue  of  the  aorta  only  touches  the  fibrous  arterial  zone  opposite  the  angle, 
or  at  the  summit  of  the  three  festoons  which  the  origin  of  the  aorta  exhibits.  The  arterial  zone  may  be  con- 
sidered as  the  tangent  of  the  three  festoons. 

t  While  the  origin  of  the  nerves  exercises  a  great  influence  on  their  functions,  the  place  from  whence  the 
arteries  originate  appears  to  be  of  but  little  consequence,  and  is,  at  all  events,  very  secondary.  We  cannot 
agree  in  the  opinion  of  Walther,  that  the  origin  of  the  arteries  of  an  organ  are  intimately  connected  with  the 
mode  of  its  existence,  and  with  the  functions  which  it  performs. 

^  [For  special  information  on  the  varieties  in  the  distribution  of  the  arteries,  the  reader  is  referred  to  Hal- 
ler, Icones  Anatomicce,  1756;  Murray,  Descriptio  Arteriarum,  &c.,  1783-98;  Barclay,  Description  of  the  Ar- 
teries, <fec.,  1818  ;  Tiedemann,  Tabula;  Arteriarum,  &c.,  !822  ;  and  to  R.  Quain's Anatomy  of  the  Arteries,  &c., 
with  drawings  by  J.  Maclise,  1840,  1841.1 


THE  ARTERIES.  497 

that  such  is  the  intention  of  the  curvatures  described  by  the  internal  carotid  and  the 
vertebral  arteries.  Bichat,  it  is  true,  has  objected  to  this,  that,  in  a  system  of  commu- 
nicating and  permanently  distended  canals,  the  curvature  can  have  no  influence  upon 
the  rapidity  of  the  fluid  circulating  through  them.  But  I  would  answer,  that  this  prin- 
ciple, though  true  in  reference  to  a  system  of  inextensible  tubes,  is  not  so  when  applied 
to  a  system  of  dilatable  canals  like  the  arteries.  In  the  latter  case,  in  fact,  part  of  the 
momentum  acts  against  the  curvature  itself,  and  straightens  it  in  a  certain  degree,  and 
in  this  way  there  is  a  loss  of  some  portion  of  the  original  momentum. 

In  some  arteries  this  tortuous  condition  is  acquired,  in  others  it  results  from  the  prog- 
ress of  age.  It  proceeds  from  elongation  of  tne  arteries,  which  is  itself  produced  in  the 
following  manner :  At  each  ventricular  systole,  the  arteries  tend  to  become  elongated 
a«  well  as  dilated.  In  the  aged,  and  especially  in  those  whose  heart  is  very  powerful, 
this  tendency  to  become  elongated  produces  an  actual  and  permanent  elongation,  as 
may  be  seen  in  the  abdominal  aorta  and  in  the  conunon  iliac,  the  humeral,  and  the  radial 
arteries,  which,  in  almost  aU  old  subjects,  present  alternate  curvatures,  that  are  never 
met  with  in  the  infant  and  the  adult.  It  has  been  incorrectly  stated,  that  at  each  sys- 
tole of  the  heart  the  curves  were  diminished,  or  manifested  a  tendency  to  be  dimin- 
ished :  on  the  contrary,  the  curves  increase.  This  increase  of  curve  is  evidently  per- 
ceived in  observing  the  tempered  artery  during  the  systole  of  the  ventricles.  If  an  ar- 
tery is  injected,  its  branches,  at  each  stroke  of  the  piston,  become  more  flexuous.  If 
the  arteries  were  straightened,  the  dilatations  and  the  calcareous  deposites  would  not  be 
constantly  observed  on  the  side  of  the  convexity  of  the  curves. 

Let  us  remark,  that  the  dilatation  of  the  arteries  is,  just  as  much  ^ls  their  elongation, 
a  cause  of  the  increase  of  their  flexuosity. 

The  flexuosities  of  the  arteries  are  of  a  twofold  order,  zigzag  and  spiral.  The  former 
are  more  frequent ;  the  latter  are  especially  noticed  in  the  ovarian  or  testicular,  uterine, 
and  sometimes  facial  arteries. 

We  may  also  consider  as  acquired  the  tortuous  condition  assumed  by  collateral  arte- 
rial branches,  after  the  obliteration  of  the  main  trunk.* 

Anastomoses  of  the  Arteries. 

During  their  course,  the  arteries  communicate  with  each  other  by  certain  branches, 
which  sometimes  unite  two  different  trunks,  and  sometimes  form  a  connexion  between 
two  parts  of  the  same  trunk.  This  mode  of  communication  is  called  anastomosis  {ava, 
by.  and  arofia,  a  mouth).     There  are  several  kinds  of  anastomoses. 

Anastomosis  by  inosculation,  or  by  loops,  in  which  two  vessels  running  in  opposite  di- 
rections open  into  each  other  by  their  extremities  and  form  a  loop. 

Attastomosis  by  transverse  communication,  as  when  two  parallel  trunks  are  united  by 
means  of  a  branch  at  right  angles  to  their  own  direction :  for  example,  the  anterior  com- 
municating artery  of  the  brain. 

Anastomosis  by  convergence,  in  which  two  arterial  branches  unite  at  an  acute  angle  to 
form  a  larger  artery,  as  in  the  union  of  the  vertebral  arteries  to  form  the  basilar  trunk. 

By  means  of  the  anastomosis  by  inosculation  or  by  loops,  which  is  the  most  common 
method  of  communication,  uninterrupted  collateral  channels  are  established  along  the 
great  arterial  trunks,  the  place  of  which  they  may  even  supply.  The  existence  of  these 
anastomoses,  and  the  power  possessed  by  arteries  of  becoming  enlarged  to  an  almost 
indefinite  extent,  originated  the  bold  idea  of  attempting  to  tie  even  the  largest  arte- 
rial trunks. 

Anastomoses  by  inosculation  are  sometimes  useful  in  regulating  the  distribution  of 
blood,+  and  spreading  out  the  origins  of  arteries  over  a  more  extended  space.  Thus,  by 
means  of  several  series  of  arches,  the  superior  mesenteric  artery  gives  off  branches  which 
proceed  at  right  angles  to  the  small  intestine  throughout  its  whole  length. 

Forms  and  Relations. 

The  arteries  represent  regular  cylinders  when  they  give  off  no  branch,  and  cones,  or, 
rather,  a  series  of  decreasing  cylinders,  when  they  gradually  diminish  by  giving  off  a 
certain  number  of  branches.  Their  cylindrical  form,  together  with  the  looseness  of  the 
surrounding  cellular  tissue,  preserves  them  from  a  number  of  accidents.  Thus,  the  hu- 
meral and  the  femoral  arteries  glide  over  the  head  of  the  humerus  and  femur  in  disloca- 
tions of  these  bones ;  and  so  the  carotid  arteries,  contrary  to  all  apparent  probability, 
sometimes  escape  uninjured  in  incised  wounds  of  the  neck. 

The  arteries  have  relations  with  many  other  parts.  With  the  bones,  being  supported 
by  them,  and  more  'or  less  closely  approximated  to  them.  Thus,  the  aorta  is  applied  to 
the  vertebral  column,  and  the  arteries  of  the  limbs,  after  escaping  from  the  trunk,  become 

*  There  are  flexuosities  originating  in  malformation,  by  deviation  or  by  fracture.     In  a  case  of  fracture  of 
the  neck  of  the  femur,  the  femoral  artery  described  very  marked  inflections  at  the  hip.   This  was  also  the  case 
in  a  luxation  of  the  femur  with  considerable  shortening.     The  aorta  becomes  very  flexuous  in  cases  cf  hunch 
backs. 

t  [The  retia  mirabilia  of  arterial  vessels,  found  in  some  animals,  are  examples  of  the  repeated  subdmsioD, 
and  anastomosis  of  arteries.] 

R  R  R 


498  ANGEIOLOGY. 

^pliea  to  the  corresponding  bones,  their  course  along  which  is  marked  by  a  depression 
and  against  which  they  may  easily  be  compressed  (see  Osteology). 

From  the  relations  of  the  arteries  with  the  articulations,  some  important  practical  in- 
ferences are  derived.  The  arteries  always  occupy  the  aspect  of  flexion  ;  and  as  flexion 
is  performed  in  the  larger  articulations  of  a  limb  alternately  in  opposite  directions,  the 
arteries  are  observed  to  alter  their  relative  position,  as  it  were,  to  regain  the  aspect  ot 
flexion.  This  is  seen  in  the  femoral  artery  as  it  becomes  popliteal,  and  also  in  the 
brachial,  which  at  first  lies  in  the  cavity  of  the  axilla,  and  then  turns  forward  at  the 
bend  of  the  elbow.  In  consequence  of  this  arrangement,  the  arteries  are  protected  by 
the  habitual,  and,  as  it  were,  instinctive,  position  of  the  Umbs. 

On  the  other  hand,  the  proximity  of  certain  arteries  to  articulations,  and  the  absence 
of  any  curvatures  in  such  situations,  may  explain  the  occurrence  of  rupture  of  these 
vessels  in  dislocation,  and  often,  also,  in  immoderate  attempts  at  reduction. 

With  the  Muscles. — The  muscles  are  the  essential  protectors  of  the  arteries,  which 
they  separate  from  the  skin.  There  are  large  cellular  spaces  in  the  centre  of  the  limbs 
for  the  reception  of  the  principal  arteries,  which  are  thus  removed  from  the  influence  of 
external  violence. 

Most  arteries  have  a  special  muscle,  which  may  be  termed  their  satellite  muscle.  Thus, 
the  sartorius  is  the  satellite  muscle  of  the  femoral  artery ;  the  sterno-cleido-mastoideus 
of  the  common  carotid ;  the  biceps  of  the  brachial  artery,  &c. 

With  the  Skin. — Some  arteries  are  sub-cutaneous,  or,  rather,  sub-aponeurotic,  in  a 
certain  part  of  their  extent ;  and  in  large  arteries,  this  is  almost  always  at  the  point 
where  they  emerge  from  the  trunk,  as  in  the  femoral  artery.  The  arteries  of  the  cra- 
nium are  situated  between  the  skin  and  the  epicranial  aponeurosis  in  the  whole  of  their 
extent.  The  importance  of  these  relations  in  reference  to  compression  of  the  vessels 
may  be  easily  conceived. 

With  the  Veins. — The  arteries  are  always  in  relation  with  certain  veins,  which  are  ap- 
plied to  them.  When  there  are  two  satellite  veins  {vence  comites)  for  one  artery,  the  lat- 
ter vessel  is  constantly  placed  between  the  two  veins. 

With  the  Nerves. — ^The  arteries  support  the  plexuses  of  nerves  distributed  to  the  or- 
gans of  nutritive  life.  We  may  even  regard  their  plexuses  as  forming  an  accessory  coat 
to  this  set  of  vessels.  Other  nerves,  though  not  so  immediately  in  contact  with  the  ar- 
teries, have  a  constant  relation  with  them.  This  it  is  of  importance  to  know,  so  that 
the  nerves  may  be  avoided,  or  that  they  may  direct  the  operator  in  applying  a  ligature  to 
the  vessels  themselves.     For  each  artery  it  may  be  said  there  is  one  satellite  nerve. 

With  the  Aponeurotic  Sheaths. — ^The  principal  artery  of  a  limb  is  provided  with  a  fibrous 
sheath,  which  belongs  to  it  in  common  with  its  veins,  and  often  with  its  accompanying 
nerve.  When  an  artery  perforates  a  muscle,  it  is  protected  in  its  passage  by  a  sheath 
or  aponeurotic  arch,  which  prevents,  or  at  least  moderates,  the  compression  during  the 
contraction  of  the  muscle. 

Lastly,  the  arteries  are  surrounded  by  a  loose  cellular  sheath,  which  allows  of  their 
dilatation  and  their  alterations  in  position.  The  looseness  of  this  cellular  tisssue  favours 
the  displacement  of  arteries  during  the  infliction  of  wounds,  and  enables  us  to  isolate 
these  vessels  by  blunt  instruments,  which  cannot  injure  them.*  As  the  nutritious  ves- 
sels reach  the  coat  of  the  arteries  through  this  sheath,  we  can  easily  understand  the  im- 
propriety of  separating  the  vessel  from  it  too  extensively  in  tying  the  arteries,  t 

Termination  of  the  Arteries. 

The  divisions  of  the  arteries  are  not  so  numerous  as  would  at  first  sight  appear.  The 
number  of  successive  divisions,  commencing  at  the  aorta,  is  not  more  than  twenty. 

The  arteries  terminate  in  the  substance  of  organs.  The  number  of  arteries  distrib- 
uted to  each  organ  is  in  proportion  to  the  activity  of  its  functions  ;  secreting  organs  are 
much  more  plentifully  supplied  with  vessels  than  those  in  which  the  function  of  nutri- 
tion only  is  performed.  Soemmering,  Prochaska,  and  others,  have  observed  that  the 
actual  termination  of  the  arteries  is  different  in  different  organs.  Referring  for  farther 
details  upon  this  subject  to  textural  anatomy,  I  shall  content  myself  with  stating  here, 
1st,  that  the  arteries  terminate  in  the  capillary  system,  through  the  medium  of  which 
they  become  continuous  with  the  veins,  as  is  demonstrated  even  by  the  coarsest  in- 
jections ;  2d,  that  the  arteries  enter  only  in  a  very  slight  degree  into  the  composition 
of  the  capillary  system,  which  is  essentially  venous ;  this  may  be  ascertained  by  in- 
jecting the  arteries  of  an  organ,  the  venous  capillary  system  of  the  same  having  been 
previously  injected  by  the  veins  ;  it  will  then  be  perceived  that  the  arteries  enter  but 
very  little  into  the  formation  of  the  capillary  system,  and  that  they  cease  to  exist  as 
soon  as  they  have  communicated  with  it.  If  it  were  objected  that,  through  this  prep- 
aration, the  injected  liquid  might  have  passed  over  from  the  venous  capillary  system  into 

*  [Another  ii^portant  result  of  this  is,  that  a  divided  artery  is  enabled  to  retract  within  its  sheath.  In  the 
abdomen  and  head  this  slieath  scarcely  exists.] 

t  I  have  seen  a  ligature  of  the  primitive  carotid  which  had  been  laid  b»re  to  too  great  an  extent  followed 
by  a  consecutive  hemorrhage  and  death. 


A 


V. 

\      THE    ARTERIES.  4^ 


ffie  arterial,  I  would  remark,  that  the  impossibility  of  this  reflux  is  one  of  the  most  clear- 
ly demonstrated  facts  in  anatomy. 

Structure  of  Arteries. 

The  walls  of  an  artery  are  composed  of  three  coats  :  an  external,  a  middle,  and  an  in- 
ternal.* 

The  External  Coat. — This  is  generally  called  the  cellular  coat,  because  it  is  in  some 
measure  continuous  with  the  surrounding  cellular  tissue.  Scarpa  erroneously  regarded 
it  as  not  forming  an  integrant  part  of  the  arteries.  It  consists  of  a  filamentous,  areolar, 
and,  as  it  were,  felted  tissue,  which  is  never  charged  with  fat  or  infiltrated  with  se- 
rum, and  which  appears  to  me  to  present  all  the  characters  of  the  dartoid  tissue.  I 
believe  that  the  contractility  which  has  been  attributed  to  the  middle  coat  is  altogether 
dependant  upon  this.t  It  is  the  only  coat  which  remains  undivided  after  the  appUca- 
tion  of  a  ligature. 

The  Proper  or  Middle  Coat. — The  characteristic  properties  of  arteries  are  chiefly  de- 
pendant upon  this  coat.  It  is  composed  of  circular  fibres,  which  interlace  at  very  acute 
angles,  but  which  do  not  present  the  spiral  arrangement  admitted  by  some  authors.  From 
its  yellow  colour  and  its  elasticity,  it  has  been  called  the  yellow  or  elastic  coat.  It  is  ex- 
tensible longitudinally  and  transversely.  It  is  very  fragile,  is  easily  torn  by  longitudinal 
extension,  and  is  cut  by  a  ligature.  It  is  proportionally  thinner  in  the  great  than  in  the 
small  arteries.  This  coat  is  of  the  same  nature  as  the  yellow  elastic  ligaments,  and  is 
therefore  not  muscular.  Moreover,  chemical  analysis  shows  that  it  contains  no  fibrine  ; 
direct  irritation  develops  no  contractility  in  it ;  and  the  supposed  phenomena  of  irrita- 
bihty  pointed  out  by  Haller  may  be  entirely  attributed  to  elasticity.  It  should  be  re- 
marked that  the  middle  coat  may  be  separated  in  several  distinct  layers,  which  are,  how- 
ever, not  independent  of  each  other ;  while  the  most  external  layers  present  a  strongly- 
marked  fibrous  linear  disposition,  the  most  internal  exliibit  an  equally  marked  lamellar 
one ;  indeed,  to  such  extent,  that  authors  have  considered  as  a  dependance  of  the  inter- 
nal coat  the  layer  of  yellow  tissue  which  is  in  contact  with  the  internal  membrane, 
properly  so  called. 

The  Internal  Coat. — It  is  a  transparent  pellicle  of  extreme  tenuity ;  it  must  be  care- 
fully distinguished  from  the  subjacent  layer,  which  is  almost  always  dissected  off  with 
it.  It  is  of  a  pale  pink  colour,  and  is  lubricated  with  serosity.  It  appears  to  be  of  the 
nature  of  serous  membranes,  of  which  it  presents  the  chief  characteristics,  viz.,  tenuity 
and  non- vascularity. t  It  may  even  be  said  that,  like  the  serous  membranes,  it  is  ex- 
clusively formed  by  a  lymphatic  net.  I  do  not  think  that  this  internal  coat  of  the  arter- 
ies, which  may  have  been  considered  as  a  sort  of  inorganic  glue,  is  extensible  or  elas- 
tic ;  on  the  contrary,  in  arteries  in  a  non-distended  state,  this  coat  exhibits  the  appear- 
ance of  folds  which  disappear  by  distension. 

Vessels  and  Nerves. — The  arteries  and  veins  distributed  to  the  coats  of  the  arteries  are 
called  vasa  vasorum.  In  regard  to  the  question  whether  the  arteries  receive  any  nerves, 
or  whether  the  nervous  plexuses  which  accompany  them  are  only  intended  for  the  or- 
gan to  which  the  vessels  are  distributed,  I  would  observe,  that  it  has  appeared  to  me 
that  several  filaments  of  the  great  sympathetic  nerve  were  lost  in  the  thickness  of  the 
aorta,  and  it  is  probable  that  the  same  disposition  exists  in  regard  to  the  less  consid- 
erable arteries.  As  to  the  vasa  vasorum,  some  believe  they  arise  from  the  neighbour- 
ing vessels,  while  others  are  of  opinion  that  they  are  derived  from  the  vessels  them- 
selves to  which  they  belong.  I  adopt  the  latter  opinion,  and  believe  that  they  mostly 
arise  from  the  arteries  to  which  they  are  attached.  The  venous  vasa  vasorum  of  the 
arterial  coats  join  the  nearest  veins. 

Preparation. 
The  preparation  of  an  artery  consists  in  separating  it  from  the  neighbouring  parts,  at 
the  same  time  preserving  its  relations.  Most  of  the  arteries  may  be  studied  without 
any  other  preparation  than  a  careful  dissection ;  but  injections  are  necessary  in  order  to 
follow  the  smaller  branches.  The  most  convenient  injection  with  which  I  am  acquaint- 
ed is  the  following  :^  Tallow,  nine  parts ;  Venice  turpentine,  one  part ;  ivory  black,  mix 
ed  with  spirits  of  turpentine  or  varnish,  two  parts. 

*  All  the  vessels,  and  all  the  tubes  of  the  body,  are  formed  of  different  layers. 

t  All  experimenters  have  observed  that,  in  an  animal  which  dies  of  hemorrhage,  the  arteries,  during  the 
last  moments  of  its  life,  lose  a  considerable  part  of  their  caliber,  -which  is  restored  to  them  immediately  after 
death.  This  phenomenon,  which  appears  at  first  sight  to  be  in  opposition  to  the  absence  of  the  contractility, 
properly  so  called,  of  the  middle  coat,  may  be  easily  accounted  for  by  the  tonic  contractility  of  the  dartoid 
tissue.  The  presence  of  this  tissue  may  also  account  for  the  smallness  or  the  contraction  of  the  pulse,  in  op- 
position with  its  fulness,  a  double  character  which  is  sometimes  met  in  the  same  individual,  and  in  the  same 
diseases,  at  short  intervals. 

t  [It  consists  of  longitudinal  fibres,  which  are  slightly  interlaced,  and  are  covered  with  a  squamous  epithe- 
lium.    The  longitudinal  wrinkles  observed  in  arteries  contracted  after  death  are  produced  in  this  coat.] 

6  [The  paint  or  cold  injection  is  one  of  the  most  useful ;  it  consists  of  either  red  or  white  lead,  mixed  a»  a 
paint,  with  a  small  quantity  of  boiled  linseed  oil,  with  spirits  of  turpentine,  and  also  with  some  driers,  viz., 
sugar  of  lead  and  litharge.J  , 


500  ~^'  ANGEIOLOGY. 

The  best  injection  for  preparations  intended  to  be  preserved  is  wax,  one  part ;  tallow, 
three  parts  ;  vermilion,  indigo,  or  Prussian  blue,  first  mixed  with  spirits  of  turpentine. 

It  is  advantageous,  before  making  the  general  injection,  to  throw  in  some  turpentine 
or  spirit  varnish,  coloured  with  the  substances  mentioned  above. 

For  a  very  fine  injection  it  is  necessary  to  use  glue-size,  coloured  either  Avith  lamp- 
black or  vermilion ;  but  this  mode  of  injection  is  not  suitable  where  the  preparation  is  to 
be  preserved. 

In  order  to  place  a  tube  in  the  aorta,  saw  through  the  sternum  longitudinally  ;  keep 
tlie  two  halves  apart  by  means  of  a  small  piece  of  wood  ;  open  the  pericardium  ;  be  care- 
ful not  to  mistake  the  pulmonary  artery  for  the  aorta  ;  raise  up  the  aorta  by  a  ligature  ; 
make  an  incision  in  it  anteriorly,  and  introduce  the  pipe.  Injections  of  the  whole  body 
may  also  be  made  by  introducing  the  tube  into  a  large  artery,  such  as  the  primitive  ca- 
rotid ;  this  mode  of  injection  permits  of  injecting  the  heart  and  the  cardiac  arteries,  and 
of  avoiding  the  mutilation  of  the  arch  of  the  aorta.  The  partial  injections  in  a  whole 
subject  are  preferable  to  the  general  injections,  especially  when  such  substances  as  tal- 
low are  used,  which  are  easily  solidified.  Of  course,  an  indispensable  condition  for  the 
success  of  these  partial  injections  is  the  previous  isolation  of  the  arterial  system  that 
you  wish  to  prepare.  This  isolation  is  effected  by  ligatures  which  are  put  upon  the  large 
arteries  communicating  with  the  small  arteries  that  are  to  be  injected. 

In  injecting  the  coronary  arteries,  the  pipe  must  be  introduced  into  one  of  the  carotids. 


DESCRIPTION  OF  THE  ARTERIES. 

THE  PULMONARY  ARTERY. 

Preparation. — Description. — Relations. — Size. — Development. 

Preparation. — In  order  to  inject  the  pulmonary  artery,  the  injecting  pipe  must  be  in- 
troduced into  one  of  the  venae  cavse. 

The  pulmonary  artery,  called  vena  arteriosa  by  the  older  writers,  because  having  all 
the  external  characters  of  an  artery ;  it  nevertheless  contains  black  blood,  extends  from 
the  right  ventricle  to  the  two  lungs.  It  arises  {k,  fig.  191)  from  the  infundibuliform  pro- 
longation of  the  right  ventricle,  and  then  passes  upward  and  to  the  left  side,  crossing  in 
front  of  the  aorta,  which  is  embraced  by  its  concavity  ;  having  reached  the  left  side  of 
this  artery,  after  a  course  of  about  fourteen  or  fifteen  lines,  it  divides  into  two  trunks 
(k  k,  fig.  192),  which  proceed  transversely,  one  to  the  right,  the  other  to  the  left  lung 
(kk,  fig.  171),  where  they  terminate  by  dividing  into  branches.  From  the  point  of  di- 
vision into  the  right  and  left  branches*  a  fibrous  cord,  the  remains  of  the  ductus  arteri- 
osus, proceeds  in  the  original  direction  of  the  artery,  and  is  attached  to  the  concavity  of 
the  arch  of  the  aorta  opposite  the  left  subclavian  artery. 

At  its  origin  the  pulmonary  artery  is  covered  externally  by  the  highest  fibres  of  the 
infundibulum ;  internally  it  is  provided  with  three  sigmoid  movable  valves  (a  a  a,  fig. 
196),  which,  when  depressed,  completely  close  the  mouth  of  the  vessel.  By  careful  dis- 
section, it  is  found  that  the  pulmonary  artery  is  cut  at  its  origin  into  three  festoons,  cor- 
responding to  the  sigmoid  valves,  and  that  it  is  connected  to  the  tissue  of  the  heart  by 
its  intern5  coat,  which  is  contiguous  with  the  lining  membrane  of  the  right  cavities  of 
the  heart ;  and  also  by  prolongations  given  off  from  the  fibrous  zone,  and  attached  to  the 
convex  borders  of  the  three  festoons,  and  to  the  angular  intervals  between  them. 

Relations. — In  front  and  on  the  left  side  the  pulmonary  artery  is  convex,  and  covered 
by  the  serous  layer  of  the  pericardium,  which  is  often  separated  from  it  by  some  fat ;  be- 
hind and  on  the  right  side  it  is  concave,  and  is  in  relation  with  the  aorta,  which  it  em- 
braces.    The  right  and  left  auricles  are  in  contact  with  its  corresponding  sides. 

Size. — The  left  branch  of  the  pulmonary  artery  is  about  one  inch  in  length ;  it  is  in 
relation  behind  with  the  left  bronchus,  one  of  the  bronchial  arteries  often  passing  between 
them  ;  it  is  in  direct  relation  with  the  aorta.  In  front,  it  is  covered  by  the  serous  layer 
of  the  pericardium,  excepting  near  the  lungs,  where  the  pulmonary  veins  are  placed  in 
front  of  the  arterial  branches. 

The  right  division  of  the  pulmonary  artery  is  from  sixteen  to  eighteen  lines  in  length ; 
it  is  in  relation  in  front  with  the  vena  cava  superior,  and  with  the  ascending  portion  of 
the  aorta,  but  not  immediately,  for  the  serous  layer  of  the  pericardium  covers  both  the 
aorta  and  the  corresponding  part  of  the  pulmonary  artery.  Behind,  it  is  in  relation  with 
the  right  bronchus,  and  passes  above  the  right  auricle. 

Development. — In  the  foetus,  instead  of  the  fibrous  cord,  which  we  have  described  as 
proceeding  from  the  point  at  which  the  pulmonary  artery  divides  into  its  two  branches,! 
there  is  a  canal  called  the  ductus  arteriosus,  almost  equal  in  diameter  to  the  pulmonary 

*  See  note,  infrd. 

t  [It  was  noticed  by  Haller  and  Senac,  that  the  ductus  arteriosus  in  the  foetus,  and  the  cord  to  which  it  is 
reduced  after  birth,  arise,  not  from  the  angle  of  division  into  the  right  and  left  pulmonary  arteries,  but  from 
the  left  pulmonary  artery  itself :  this  is  an  interesting  and  important  fact  in  reference  to  the  development  of 
th«  great  vessels  issuing  from  the  heart.] 


THE    AOETA. 


d9l 


artery  itself,  the  course  of  which  vessel  it  pursues ;  at  this  time  the  right  and  left  branch- 
es of  the  pulmonary  artery  are  very  small.  At  birth  the  whole  of  the  venous  blood  pro- 
ceeds to  the  lungs,  none  of  it  passing  through  the  ductus  arteriosus,  which  then  becomes 
obliterated. 


Fig.  198. 


THE  AORTA. 

Preparation. — Definition. — Situation. — Direction. — Size. — Division  into  the  Arch  of  the  Am- 
ta,  the  Thoracic  Aorta,  and  the  Abdominal  Aorta. 
Preparation. — The  aorta  may  be  studied  without  having  been  injected.*  In  order  to 
study  it  in  an  injected  subject,  the  median  incision  made  for  the  purpose  of  introducing 
the  injection  must  be  prolonged  down  to  the  pubes.  Then  disarticulate  the  clavicles, 
separate  the  two  sides  of  the  thorax,  even  so  far  as  to  break  some  of  the  ribs,  and  keep 
them  separate  by  introducing  a  piece  of  wood ;  cut  through  the  abdominal  parietes,  and 
turn  the  left  lung  over  to  the  right  side. 

The  aorlo  {aoprri,  arteria  magna,  arteriamm  omnium  mater,  ah  c  d,fig.  198),  the  com- 
mon origin  of  all  the  arteries  of  the  human  body,  commences  at  the  left  ventricle,  and 
terminates  by  bifurcating  (at  d)  opposite  the  fourth  lumbar  vertebra. 

Situation. — It  is  situated  deeply  in  the  thoracic  and  abdominal  cavities,  along  the  ver- 
tebral column,  which  affords  it  both  support  and  protection.  In  those  animals  in  which 
the  aorta  is  prolonged  beyond  the  trunk,  the  vertebral  column  accompanies  the  vessel, 
and  forms  a  bony  canal  or  sheath  for  it,  distinct  from  the  canal  for  the  spinal  cord. 

Direction. — Immediately  after  its  origin,  the  aorta  advances  towards  the  right  side  (a, 
fig.  198),  and  almost  directly  afterward  pro- 
ceeds upward,  describing  a  slight  curve,  the  con- 
vexity of  which  is  turned  forward  and  to  the 
right,  and  the  concavity  backward  and  to  the  left. 
After  leaving  the  pericardium,  it  changes  its 
direction,  becomes  suddenly  curved,  and  passes 
almost  horizontally  from  the  right  to  the  left, 
and  from  before  backward,  to  reach  the  left  side 
of  the  vertebral  column,  on  a  level  with  the  third 
dorsal  vertebra,  at  which  point  (6)  it  makes  a 
third  curve,  and  becomes  vertical  and  descend- 
ing. Having  reached  the  diaphragm  (at  c),  it 
incUnes  a  little  to  the  right  side,  in  order  to  gain 
the  median  line,  and  to  pass  through  the  ring, 
or,  rather,  the  canal,  formed  for  it  by  the  pillars 
of  the  diaphragm.  From  this  point  to  its  ter- 
mination, it  rests  upon  the  middle  of  the  anteri- 
or surface  of  the  vertebral  column. 

Varieties  in  its  Direction. — It  is  not  a  very 
rare  occurrence  to  find  the  aorta  curving  over 
to  the  right  instead  of  the  left  side — a  disposi- 
tion which  may  either  be  accompanied  with  a 
complete  transposition  of  the  thoracic  and  ab- 
dominal viscera,  or  may  be  independent  of  it. 

Size. — The  several  portions  of  the  aorta  have 
not  a  uniform  caliber  ;t  but  its  gradual  decrease, 
in  this  respect,  bears  no  direct  proportion  to 
the  number  and  size  of  the  branches  given  off" 
from  it. 

At  its  origin  it  always  presents  three  ampul- 
lae, which  correspond  to  the  sigmoid  valves ; 
they  are  called  the  sinuses  of  the  aorta,  or  sinuses 
of  Valsalva.  They  exist  originally,  and  must, 
therefore,  be  distinguished  from  a  dilatation 
found  on  the  convex  side  of  the  arch  of  the  aor- 
ta in  old  subjects,  and  called  the  great  sinus  of 
the  aorta.     This  dilatation  results  entirely  from  the  impulse  of  the  current  of  the  blood. 

The  caliber  of  the  aorta,  moreover,  differs  exceedingly  in  different  subjects,  even 
when  there  is  no  appreciable  organic  lesion  :t  it  should  be  remarked,  however,  that  the 
thickness  of  its  coats  is  not  at  all  in  proportion  with  its  caliber. 

*  It  will  be  advantageous  to  study  the  aorta  in  the  same  subject  in  which  the  viscera  have  already  been  ex- 
amined. 

t  Thus,  the  caliber  of  the  commencement  of  the  aorta,  compared  with  that  of  its  termination,  is  generally 
as  five  to  three  ;  hence  the  diminution  is  not  by  any  means  proportionate  to  the  number  of  branches  arising 
from  It,  for  the  united  calibers  of  its  collateral  braiiches  would  much  exceed  that  of  the  main  vessels. 

t  Thus,  I  have  seen  a  case  in  which  the  aorta  was  4  inches  8  lines  in  circumference  opposite  the  arch,  and 
2  inches  6  lines  at  its  lower  end  :  the  latter  is  the  usual  size  of  the  vessel. 


502  ANGEIOLOGY. 

The  aorta  is  generally  divided  into  three  portions,  viz.,  the  arch  of  the  aorta,  the  tho- 
racic aorta,  and  the  abdominal  aorta.  The  two  latter  portions  form  together  the  aorta  de- 
acendens. 

The  Arch  of  the  Aorta. 

I  shall  give  this  name  to  all  that  part  of  the  aorta  (a  I,  fig.  198^  which  is  comprised 
between  its  origin  from  the  left  ventricle  and  the  point  where  it  is  crossed  by  the  left 
bronchus.* 

The  direction  of  the  arch  of  the  aorta  is  neither  transverse  nor  antero-posterior,  but 
oblique  from  the  right  to  the  left  side,  and  from  before  backward  ;  so  that  it  is  anterior, 
median,  and  substernal  in  its  first  portion,  and  posterior  at  its  termination,  and  in  rela- 
tion with  the  left  side  of  the  vertebral  column.  In  consequence  of  these  relations,  aneu- 
risms of  the  anterior  part  of  the  arch  of  the  aorta  frequently  affect  the  sternum,  while 
aneurisms  of  the  posterior  portion  affect  the  vertebral  column. 

Relations. — We  shall  examine  the  relations  of  the  arch  of  the  aorta,  first  in  its  pericar- 
diac or  ascending  portion,  and  then  in  its  horizontal  and  descending  portions  taken  to- 
gether. 

The  Pericardiac  Portion  (/,  fig.  191). — Concealed,  as  it  were,  in  the  substance  of  the 
heart  at  its  origin,  it  is  in  relation  in  front  with  the  infundibulum  of  the  right  ventricle, 
and  behind  with  the  concavity  of  the  auricles,  which  are  moulded  upon  it.  On  the  right, 
it  rests  upon  the  groove  between  the  infundibulum  and  the  right  auriculo-ventricular  or- 
ifice ;  on  the  left,  it  is  in  relation  with  the  puhnonary  artery.  It  is  important  to  note 
the  practical  consequences  of  these  relations.  I  have  recently  seen  a  communication 
between  the  aorta  and  the  infundibulum.  Again,  aneurisms  of  the  origin  of  the  aorta 
may  burst  into  the  auricles. 

After  leaving:  the  heart,  this  portion  of  the  aorta  is  surrounded  on  all  sides,  but  to  a 
greater  extent  in  front  than  behind,  by  the  serous  layer  of  the  pericardium,  which  forms 
a  sort  of  additional  coat  for  it,  excepting  in  front,  below,  and  on  the  left  side,  where  it  is 
in  immediate  contact  with  the  pulmonary  arteiy,  as  that  vessel  turns  round  it.  Behind, 
this  portion  of  the  aorta  is  in  relation  with  the  right  division  of  the  pulmonary  artery  ; 
on  the  right,  with  ttie  vena  cava  superior.  It  follows,  therefore,  that  the  pulmonary  ar- 
tery on  the  one  hand,  and  the  aorta  on  the  other,  form  two  half-rings,  like  the  branches 
of  the  letter  x,  which  embrace  each  other  by  their  concavities.  The  pericardiac  portion 
of  the  aorta  is  situated  oeneath  the  sternum,  from  which  it  is  separated  by  the  pericar- 
dium and  the  anterior  mediastinum 

The  Second  Portion,  comprising  the  Horizontal  and  Descending  Portions  of  the  Arch. — 
On  the  outside  of  the  pericardium,  the  aorta  is  in  relation,  in  front  and  on  the  left  side, 
with  the  left  pleura,  and  is  separated  by  it  from  the  corresponding  lung,  which  is  exca- 
vated at  that  point.  The  phrenic  and  pneumogastric  nerves  are  also  in  immediate  con- 
tact with  it.  Behind,  and  on  the  right  side  (/,  fig.  171),  it  is  in  direct  relation  with  the  tra- 
chea, the  commencement  of  the  left  bronchus,  the  oesophagus,  the  thoracic  duct,  the  re- 
current nerve,  the  vertebral  column,t  and  a  great  nmnber  of  lymphatic  glands. 

By  its  convexity,  which  is  directed  upward,  it  gives  origin  to  three  large  arterial  trunks, 
viz.,  proceeding  from  the  right  to  the  left  side,  the  brachio-cephalic  (e,fig.  198)  or  innom- 
inate, the  left  common  carotid  (f),  and  the  left  subclavian  {g)  arteries.  The  highest  point 
of  the  arch  is  opposite  the  origin  of  the  brachio-cephalic  artery  in  the  infant,  and  that  of 
the  left  subclavian  in  old  subjects.  The  distance  between  the  fourchette  of  the  sternum 
and  the  highest  point  of  the  aortic  arch  varies  in  different  ages  and  individuals :  it  is 
generally  from  ten  to  twelve  lines  in  the  adult ;  it  is  much  less  in  the  aged  and  in  the 
newborn  infant,  but  for  very  different  reasons  ;  in  the  infant  it  is  owing  to  the  undevel- 
oped condition  of  the  sternum,  but  in  advanced  age  it  depends  upon  dilatation  of  the  arch 
of  the  aorta  ;  in  some  adults,  also,  we  find  the  distance  very  inconsiderable,  and  this  is 
important  in  reference  to  the  operation  of  tracheotomy. 

By  its  concavity,  which  is  directed  downw^ard,  the  arch  of  the  aorta  is  in  relation  with 
the  left  recurrent  nerve,  which  embraces  it,  as  it  were,  in  a  loop,  having  its  concavity 
turned  upward;  with  the  left  bronchus  (p,fig.  171  ;  also,^"'.  198),  which  is  placed  be- 
hind the  horizontal  portion  of  the  arch,  and  then  becomes  situated  in  front  of  its  descend 
ing  portions,  so  that  the  aorta,  during  its  curvature,  has  two  different  relations  with  this 
air-tube ;  and,  lastly,  with  a  very  great  number  of  lymphatic  glands,  which  in  some 
measure  fill  up  the  concavity  of  the  aortic  arch. 

Anomalies  of  the  Arch  of  the  Aorta.— A  very  remarkable  anomaly  of  the  arch  of  the 
aorta  has  been  observed,  in  which  the  vessel,  being  simple  at  its  origin,  divides  into  two 
trunks,  which  pass,  one  in  front  and  the  other  behind  the  trachea,  and  then  reunite  to 
form  the  descending  aorta.     The  aorta  sometimes  presents  traces  of  a  subdivision  into 

*  The  limits  of  the  arcn  of  the  aorta  are  not  weJ  defined  :  most  authors  exclude  the  first  curve  of  the  ar- 
tery The  lower  boundary  is  marked  by  the  origin  of  the  left  subclavian,  according  to  some  ;  by  the  left  bron- 
chus, according  to  others  ;  and.  lastly,  according  to  a  great  many,  by  the  articulation  of  the  fourth  with  the 
fifth  dorsal  verteora, 

t  I  have,  I  believe,  satisfactorily  demonstrated,  in  another  part  of  this  work,  that  the  left  lateral  concaviti 
»f  the  vertebral  column  was  owing  to  the  presence  of  the  arch  of  the  aorta 


BRANCHES   OF   THE  AORTA.  Mg 

two  from  its  origin ;  such  a  case  appears  to  indicate  a  fusion  of  two  aortas  into  one,  for 
we  then  find  five  sigmoid  valves. 

The  Thoracic  Aorta. 

The  thoracic  aorta  {b  c,  Jig.  198)  is  situated  in  the  posterior  mediastinum,  along  the  lelt 
side  of  the  vertebral  column,  and  it  projects  into,  and  encroaches  upon,  the  left  cavity 
of  the  chest. 

Relations. — It  corresponds,  on  the  left  side,  with  the  lung,  from  which  it  is  separated 
by  the  left  wall  of  the  posterior  mediastinum ;  on  the  right,  it  is  in  relation  with  the 
oesophagus,  the  vena  azygos,  and  the  thoracic  duct ;  in  front,  with  the  left  pulmonary  m- 
teries  and  veins  above  ;  with  the  oesophagus  (h)  below,  which  canal  becomes  anterior  to 
it  before  passing  through  the  oesophageal  opening  in  the  diaphragm,  and  with  the  peri- 
cardium in  the  middle,  by  which  it  is  separated  from  the  posterior  surface  of  the  heart ; 
behind,  it  is  in  relation  with  the  vertebral  column,  the  thoracic  duct  passing  between 
them  above. 

The  thoracic  aorta  is  surrounded  by  an  abundance  of  cellular  tissue,  and  by  a  number 
of  lymphatic  glands. 

Diaphragmatic  Portion  of  the  Thoracic  Aorta. — The  diaphragm  does  not  form  a  simple 
orifice  or  an  aponeurotic  arch  for  the  aorta,  but  its  crura  («  s,fig.  199)  are  arranged  into 
a  muscular  semi-canal,  from  fifteen  to  eighteen  lines  in  length,  and  terminating  below 
by  a  tendinous  arch.  The  aorta  is  accompanied,  while  passing  through  this  canal,  by 
the  thoracic  duct*  and  the  vena  azygos,  and  it  inclines  a  little  to  the  right  side,  in  order 
to  become  anterior  to  the  vertebral  column. 

The  Abdominal  Aorta. 

The  abdominal  aorta  (c  d,Jig.  198)  occupies  the  middle  part  of  the  anterior  surface  ot 
the  vertebral  column,  and  is  in  relation  on  the  right  side  with  the  vena  cava  inferior,  and 
in  front  with  the  pancreas  and  the  third  portion  of  the  duodenum,  which  rests  immedi- 
ately upon  it ;  in  the  rest  of  its  extent  it  corresponds  with  the  adherent  borders  of  the 
mesentery,  and  with  the  peritoneum  covering  the  lumbar  region  of  the  vertebral  column. 
The  stomach  and  the  convolutions  of  the  small  intestine  separate  the  aorta  from  the  an- 
terior parietes  of  the  abdomen.  When  the  small  intestine  fdi&s  down  into  the  pelvis,  the 
abdominal  aorta  may  be  felt  immediately  behind  the  wall  of  the  abdomen,  and  may  be 
easily  compressed  there,  so  as  completely  to  intercept  the  passage  of  the  blood,  t 


BRANCHES  FURNISHED  BY  THE  AORTA  IN  ITS  COURSE. 

Enumeration  and  Classification. — Arteries  arising  from  the  Aorta  at  its  Origin,  viz.,  the  Car- 
onary  or  Cardiac. — Arteries  arising  from  the  Thoracic  Aorta,  viz.,  the  Bronchial,  tie 
(Esophageal,  the  Intercostal. — Arteries  arising  from  the  Abdominal  Aorta,  viz.,  the  Lum- 
bar, the  Inferior  Phrenic,  the  Caliac  Axis,  including  the  Coronary  of  the  Stomach,  the  He- 
patic and  the  Splenic,  the  Superior  Mesenteric,  the  Inferior  Mesenteric,  the  Spermatic,  the 
Renal,  and  the  Supra-renal  or  Capsular. 

The  aorta  is  the  common  trunk  of  all  the  branches  and  twigs  given  off  by  the  arterial 
tree.  It  alone  furnishes,  therefore,  all  the  arteries  of  the  human  body.  The  branches 
which  come  from  it  I  shall  divide  into  terminal  and  collateral  branches. 

The  terminal  branches  of  the  aorta  consist  of  the  middle  sacral  and  the  two  commcm 
iliac  arteries.  The  collateral  branches  are  very  numerous :  they  may  be  divided  into 
those  arising  from  the  pericardiac  portion  of  the  aorta,  viz.,  the  coronary  or  cardiac  ar- 
teries; those  arising  from  the  aortic  arch,  viz.,  the  brachio-cephalie,  the  left  common 
carotid,  and  the  left  subclavian :  these  we  may  consider  as  terminal  arteries,  which,  ta- 
ken together,  have  been  termed  the  ascending  aorta  in  opposition  to  the  descending 
aorta ;  those  arising  from  the  thoracic  aorta,  which  may  be  subdivided  into  the  parietal 
branches,  viz.,  the  intercostals  and  the  visceral,  viz.,  the  bronchial,  oesophageal,  and 
mediastinal  arteries ;  and,  lastly,  those  arising  from  the  abdominal  aorta,  which  may 
also  be  distinguished  as  the  parietal,  viz.,  the  lumbar  and  inferior  phrenic  arteries,  and 
the  visceral,  viz.,  the  cceliac  axis,  the  superior  and  inferior  mesenteric,  the  supra-renal, 
the  renal,  and  the  spermatic  arteries. 

Artekies  ari^no  from  the  Aorta  at  its  Origin. 
The  Coronary  or  Cardiac  Arteries. 
Dissection. — Take  off  the  serous  membrane  from  the  heart,  and  also  the  fat  which  oo- 

*  It  is  a  mistake  to  say  that  the  right  azygos  vein  passes  through  the  same  opening  as  the  thoracic  duct. 
The  ar.ygos  vein  traverses  the  evening  which  is  destined  to  tVie  passage  of  the  great  splanchnic  branch  of  the 
sympathetic  nerve. 

t  This  compression  is  very  easily  applied  in  women  immediately  after  parturition,  both  in  consequence  of 
the  relaxed  state  of  the  abdominal  parietes  allowing  them  to  be  readily  depressed,  and  also  from  the  facility 
with  which  the  small  intestines  are  moved  aside. 


504  ANGEIOLOGY. 

cupies  the  furrows  ;  in  order  to  see  distinctly  the  origin  of  these  arteries,  remove  the 
pulmonary  artery  and  the  infundibulum  of  the  right  ventricle. 

The  cardiac  or  coronary  arteries  {see  figs.  191,  192),  the  nutritious  vessels  of  the  heart, 
or,  as  it  were,  its  rasa  vasorum,  are  two  in  number,  and  are  named  right  and  left  on  ac- 
count of  their  origin,  and  also  anterior  and  posterior  from  their  distribution.  Their 
number  is  not  constant.  Thus  the  two  coronary  arteries  sometimes  arise  by  a  common 
trunk,  to  the  left  of  the  pulmonary  artery.*  Sometimes  there  arc  three  coronary  arter- 
ies ;  Meckel  has  seen  four ;  but  these  varieties  in  number  do  not  affect  their  distribu- 
tion, for  the  supernumerary  arteries  merely  represent  branches,  which,  instead  of  arising 
from  the  coronary  arteries  themselves,  proceed  directly  from  the  aorta.  I  have  recently 
seen  the  right  coronary  artery  arise  from  the  aorta  by  three  branches  in  juxtaposition, 
one  of  which  was  of  considerable  size  :  the  others  were  small. 

Origin. — They  arise  from  the  anterior  part  of  the  circumference  of  the  aorta,  imme- 
diately above  the  free  margin  of  the  sigmoid  valves,  at  the  highest  points  of  the  two 
corresponding  sinuses.  The  origins  of  these  vessels  are  so  situated,  that  their  orifices 
are  not  covered  by  the  valves  when  these  latter  are  applied  to  the  walls  of  the  aorta,  so 
that  the  heart  receives  its  arterial  blood  at  the  same  time  as  all  the  other  organs.  The 
angle  at  which  the  coronary  arteries  arise  is  extremely  obtuse,  so  that  the  course  of  the 
blood  in  them  is  completely  retrograde. 

The  coronary  arteries  differ  from  each  other  in  caliber,  the  right  being  larger  than  the 
left,  and  also  in  their  course,  so  that  a  special  description  is  requisite  for  each. 

The  left  or  anterior  coronary  artery  is  destined  principally  for  the  anterior  furrow  of  the 
heart ;  it  is  concealed,  at  its  origin,  by  the  infundibulum,  from  between  which  and  the 
left  auricula  it  then  escapes,  and  entering  {e,  fig.  191)  the  anterior  furrow  of  the  heart, 
traverses  it  in  a  very  tortuous  manner,  and  anastomoses,  at  the  apex,  with  the  right  or 
posterior  coronary  artery.  Not  unfrequently  this  artery  divides  into  two  branches,  one 
of  which  runs  along  the  anterior  furrow,  while  the  other  passes  upon  the  anterior  sur- 
face of  the  left  ventricle.  In  this  course,  opposite  the  base  of  the  ventricles,  the  artery 
gives  off  an  auriculo- ventricular  branch,  which,  arising  at  a  right  angle,  enters  the  left 
auriculo-ventricular  furrow,  and,  passing  along  it,  turns  round  the  base  of  the  left  ven- 
tricle, as  far  as  the  posterior  inter- ventricular  furrow  {e,fig.  192),  where  it  anastomoses 
with  the  right  coronary  artery. 

The  right  or  posterior  coronary  arteiy  is  larger  than  the  left  ;  it  arises  to  the  right  of 
the  infundibulum,  between  that  part  and  the  right  auricle.  Immediately  after  its  origin 
it  is  surrounded  with  a  large  quantity  of  fat,  and  turns  directly,  so  as  to  gain  the  right 
auriculo-ventricular  furrow.  At  the  upper  end  of  the  posterior  inter-ventricular  furrow 
(e,  fig.  192)  it  bends  at  a  right  angle,  and  entering  the  furrow,  runs  along  it  to  the  apex 
of  the  heart,  where  it  anastomoses  with  the  left  coronary  artery.  At  the  point  where  it 
changes  its  direction,  the  right  coronary  artery  gives  off  a  branch,  which  anastomoses 
with  the  auriculo-ventricular  branch  of  the  left  artery. 

From  this  description,  it  follows  that  the  cardiac  arteries  and  their  principal  divisions 
occupy  the  furrows  of  the  heart ;  that  they  form  two  vascular  circles,  which  are  placed 
at  right  angles  to  each  other  like  the  furrows  themselves  ;  that  the  auriculo-ventricular 
circle  is  formed  on  the  right  by  the  trunk  of  the  right  cardiac,  and  on  the  left  by  a  branch 
of  the  left  cardiac  artery ;  that  the  vessels  forming  these  two  circles  are  tortuous,  but 
especieilly  those  on  the  ventricles,  because  that  part  of  the  heart  is  subject  to  greater 
variations  in  its  dimensions  than  the  part  with  which  the  auriculo-ventricular  circle  is 
in  relation;  and,  lastly,  that  both  coronary  arteries  anastomose  by  inosculation,  and 
therefore  can  easily  supply  each  other. 

All  the  arteries  of  the  heart  proceed  from  these  two  circles.  The  auriculo-ventricular 
circle  gives  off  some  ascending  or  auricular  branches,  an  aortico-pulmonary  branch  to  the 
origins  of  the  aorta  and  pulmonary  artery,  and  an  adipose  branch,  all  of  which  were 
pointed  out  by  Vieussens  ;  also  some  descending  or  ventricular  branches,  the  two  prin- 
cipal of  which  run  somewhat  obliquely  along  the  right  and  left  borders  of  the  heart. 

The  ventricular  circle  gives  off  branches  which  penetrate  the  fleshy  fibres  at  right  an- 
gles. A  large  artery,  which  has  been  described  as  the  artery  of  the  septtim,  appears  to  be 
one  of  the  terminal  branches  of  the  left  coronary  artery ;  it  dips  into  and  is  lost  in  the 
substance  of  the  septum. 

Lastly,  the  coronary  arteries  communicate  with  the  bronchial.  They  are  very  liable 
to  calcareous  deposites.f 

Arteries  abising  from  the  Thoracic  Aorta. 
These  may  be  divided  into  visceral  branches,  all  of  which  arise  from  the  front  of  the 

*  The  coronary  arteries  were  denominated  by  the  older  anatomists,  and  especially  by  Bartholin,  coronaria 
ntedo  simplex,  modo  gemina.  Meckel,  Harrison,  and  others  have  described  cases  in  which  there  was  but  on« 
coronary  artery.  According  to  the  descriptions  of  writers  on  comparative  anatomy,  that  disposition  is  natural 
with  the  elephant. 

t  It  is  not  uncommon  from  such  deposites  to  find  cardiac  arteries  which  are  extremely  narrowed,  and  even 
obliterated.  Several  pathologists  have  considered  this  ossification  of  the  cardiac  arteries  as  the  cause  of  those 
phenomena  which  are  designated  by  the  name  of  angina  vecions ;  but  tliis  opinion  is  a  mere  hypothesis. 


THE   AORTIC    INTERCOSTAL    ARTERIES.  505 

aorta,  viz.,  the  bronchial  and  the  oesophageal,  and  parietal  branches,  which  arise  from  the 
back  of  the  aorta,  viz.,  the  aortic  intercostals. 

The  Bronchial  Arteries. 

Dissection. — Carefully  take  away  the  heart  and  pericardium,  dissect  the  bronchi,  and 
trace  these  arteries  both  to  their  origin  and  towards  their  termination. 

Number  and  Origin. — The  bronchial  arteries  {see  fig.  198)  vary  much  both  in  number 
and  origin.  There  are  generally  two  on  each  side  ;  but  sometimes  there  are  three,  or 
even  four,  arising  either  at  different  heights  or  by  a  common  trunk.  Occasionally,  one 
of  them  arises  from  the  subclavian,  or  from  the  internal  mammary,  or,  rather,  from  the 
first  intercostal,  or,  lastly,  from  the  second,  or  even  the  third  intercostal  artery. 

I  have  seen  the  inferior  thyroid  artery  give  off  a  bronchial  artery,  which,  after  run- 
ning along  the  trachea,  passed  in  front  of  the  right  bronchus,  and  anastomosed  freely 
with  the  right  bronchial  furnished  by  the  aorta.  The  right  bronchial  artery  is  always 
larger  than  the  left. 

Whatever  be  their  origin,  the  bronchial  arteries  pursue  a  tortuous  course  to  the  cor- 
responding bronchus,  and  are  usually  situated  on  its  posterior  surface.  When  the  right 
bronchial  artery  arises  from  the  aorta,  it  crosses  obliquely  over  the  lower  part  of  the  tra- 
chea. The  bronchial  arteries  always  give  some  branches  to  the  oesophagus ;  a  very 
great  number  to  the  bronchial  glands  ;  also  several  to  the  left  auricle  :  they  anastomose 
with  the  coronary  arteries  on  the  one  hand,  and  with  the  inferior  thyroid  and  the  supe- 
rior intercostal  arteries  on  the  other. 

Haller  believes  that  the  terminations  of  the  bronchial  arteries  anastomose  with  the  di- 
visions of  the  puhnonary  artery,  and  says  that  he  has  seen  free  and  evident  communica- 
tions between  them.* 

The  (Esophageal  Arteries. 

The  oesophageal  arteries  {h,fig.  198)  vary  in  number  from  three  to  seven,  and  are  re- 
markable for  their  slenderness  and  length.  They  arise  in  succession  from  the  front  of 
the  aorta,  which  they  leave  at  right  angles,  and  inamediately  curve  downward  to  reach 
the  front  of  the  oesophagus,  where  they  divide  into  extremely  slender  ascending,  and 
into  very  long  descending  branches,  from  which  are  given  off  a  numerous  series  of  twigs. 
The  superior  oesophageal  artery  almost  always  anastomoses  with  the  bronchial  arteries, 
and  the  oesophageal  branches  of  the  inferior  thyroid.  The  inferior  oesophageal  artery 
anastomoses  with  the  oesophageal  branches  derived  from  the  left  inferior  phrenic,  and 
from  the  coronary  artery  of  the  stomach. 

The  branches  from  the  oesophageal  arteries  perforate  the  muscular  coat  of  the  oesoph- 
agus, ramify  in  the  sub-mucous  cellular  tissue,  and  terminate  in  a  network  in  the  sub- 
stance of  the  mucous  membrane. 

The  Aortic  Intercostal  Arteries. 

Dissection. — In  order  to  see  the  posterior  branches,  dissect  the  posterior  spinal  mus- 
cles, and  open  the  vertebral  canal.  To  see  the  anterior  branches  or  the  intercostals, 
properly  so  called,  expose  these  vessels  on  the  inside  of  the  parietes  of  the  chest  in  the 
first  half  of  their  course,  and  then  on  the  outside  of  the  chest  to  their  termination. 

The  aortic  or  inferior  intercostals  (i  i  i'  i'.fig.  198),  so  named  to  distinguish  them  from 
the  superior  intercostal,  a  branch  of  the  subclavian,  and  from  the  anterior  intercostals, 
derived  from  the  internal  mammary,  are  generally  eight  or  nine  in  number,  the  upper 
two  or  three  intercostEil  spaces  being  supplied  by  the  superior  intercostal  branch  of  the 
subclavian. 

The  varieties  in  their  number  depend  upon  the  number  of  intercostal  spaces  which  are 
supplied  with  branches  from  the  subclavian,  and  also  upon  the  number  of  intercostal  ar- 
teries which  arise  by  a  common  trunk. 

Origin. — ^They  arise  at  various  angles  from  the  back  of  the  aorta  ;  the  superior  gen- 
erally at  an  obtuse  angle  to  gain  the  spaces  situated  above  them  ;  the  succeeding  ones 
at  different  angles,  which  are  less  and  less  obtuse,  and  sometimes  right  angles,  or  even 
acute  angles.  In  the  latter  case,  the  vessel  immediately  ascends  to  reach  the  intercostal 
space  for  which  it  is  intended.  The  right  and  left  intercostals  are  of  equal  size,  and  there 
is  little  difference  in  this  respect  between  the  superior  and  the  inferior  intercostals. 

In  consequence  of  the  aorta  being  situated  towards  the  left  side,  the  right  intercostals 
(i'  i')  are  longer  than  the  left.  They  turn  over  the  body  of  each  dorsal  vertebra,  passing 
Dchind  the  oesophagus,  the  thoracic  duct,  and  the  vena  azygos,  and  reach  the  correspond- 
ing intercostal  space.  The  left  intercostals  enter  their  proper  spaces  at  once.  Bot  h  are 
in  relation  with  the  costal  pleura  and  the  thoracic  ganglia  of  the  great  sympathetic  nerve, 
behind  which  they  are  situated.  The  lower  intercostals  on  the  left  side  are  covered  by 
the  vena  azygos  minor.  The  two  lower  intercostals  on  both  sides  are  covered  by  the 
pillars  of  the  diaphragm.  In  their  course  over  the  bodies  of  the  vertebras,  the  intercos- 
tals give  off  numerous  nutritious  branches,  which  enter  the  foramina  on  the  anterior  sur- 
face of  these  bones. 

See  note,  p.  421. 
S  8  3 


ANGEIOLOGY. 


On  reaching  the  intercostal  space,  each  artery  immediately  divides  into  an  anterior 
and  a  posterior  branch. 

The  anterior  or  intercostal  branches  are  larger  than  the  posterior,  and  may  be  regarded 
as  the  continuation  of  the  arteries  themselves  in  their  original  course.  They  are  at  first 
situated  in  the  middle  of  the  intercostal  spaces,  between  the  pleura  and  external  inter- 
costal muscles  ;  they  then  pass  between  the  external  and  the  internal  intercostals,  reach 
the  lower  border  of  the  rib  above  them,  and  are  lodged  in  the  grooves  found  in  that  sit- 
uation ;  having  reached  tlie  anterior  third  of  the  intercostal  spaces,  where  they  have  be- 
come extremely  small,  they  quit  the  grooves,  and  again  become  placed  in  the  middle  of 
the  spaces  ;  the  superior  intercostals  then  terminate  by  anastomosing  with  the  intercostal 
branches  of  the  internal  mammary,  and  the  inferior  intercostals  with  the  epigastric,  the 
phrenic,  the  lumbar,  and  the  circumflex  iliac  arteries 

During  its  whole  course,  each  intercostal  branch  is  in  relation  with  the  corresponding 
intercostal  vein  and  nerve.  The  inferior  intercostal  arteries,  commencing  at  the  fifth, 
after  leaving  the  intercostal  spaces,  are  lost  in  the  external  and  internal  oblique  muscles 
of  the  abdomen,  which,  as  we  have  seen,  form,  as  it  were,  continuations  of  the  intercostal 
muscles  (see  Myology). 

The  intercostal  branch  furnishes  numerous  ramusculi  to  the  intercostal  muscles,  the 
ribs,  the  sab-pleural  cellular  tissue,  the  muscles  which  cover  the  thorax,  and  even  to  the 
integuments.  A  very  small,  but  tolerably  constant  branch,  is  given  off  at  an  acute  angle 
from  the  artery,  at  the  moment  where  it  dips  between  the  two  sets  of  intercostals,  gains 
the  upper  border  of  the  rib  below,  and  is  lost  in  the  periosteum  and  the  muscles,  after 
running  a  variable  distance. 

The  posterior  or  dorsi-spinal  branches  pass  directly  backward  between  the  transverse 
processes  of  the  vertebrae,  on  the  inner  side  of  the  superior  costo-transverse  ligaments, 
and  each  of  them  immediately  divides  into  two  branches  :  one,  the  spinal,  which  enters 
the  inter-vertebral  foramen,  and  again  divides  into  a  vertebral  branch  for  the  bodies  of  the 
vertebrae,  and  a  medullary  branch  for  the  coverings  of  the  spinal  cord,  and  for  the  cord  it- 
self, to  the  distribution  of  which  we  shall  hereafter  return.  The  second,  or  dorsal  branch, 
is  larger  than  the  spinal,  and  forms  a  continuation  of  the  dorso-spinal  ttunk  ;  it  escapes 
behind  between  the  transverso-spinalis  and  longissimus  dorsi,  sends  some  ramifications 
between  the  longissimus  dorsi  and  sacro-lumbalis,  and  terminates  in  the  muscles  and  the 
skin. 

Artkkies  arising  fkom  the  Abdominal  Aorta. 

The  branches  furnished  by  the  abdominal  aorta  are  parietal,  viz.,  the  lumbar  and  the 
inferior  phrenic  arteries;  and  the  visceral  branches,  viz.,  the  cxliacaxis,  the  superior  and 
inferior  mesenteric,  the  spermatic,  the  renal,  and  the  middle  supra-renal  arteries.  In  refer- 
ence to  their  place  of  origin,  these  arteries  may  be  divided  into  those  which  arise  from 
the  anterior  aspect  of  the  aorta,  viz.,  the  coeliac  axis,  the  superior  and  inferior  mesenter- 
ic, and  tne-  spermatic  arteries  ;  and  those  which  arise  from  its  sides,  viz.,  the  renal,  the 
middle  supra-renal,  and  the  lumbar  arteries.  The  lumbar  arteries  might  be  regarded  as 
arising  from  the  back  of  the  aorta. 

The  Lumbar  Arteries. 


?%r.  199. 


Dissection. — Remove  the  pillars  of  tlie  diaphragm 
and  the  psoas  muscles.  In  order  to  expose  the 
dorsi-spinal  branches,  dissect  the  posterior  spinal 
muscles,  and  open  the  vertebral  canal.  To  ex- 
pose the  anterior  branches,  dissect  the  abdominal 
muscles  carefully. 

The  lumbar  arteries  {I  I,  fig.  199)  continue  the 
series  of  intercostals,  with  which  they  present  nu- 
merous analogies  in  reference  to  their  origin, 
course,  and  termination.  They  vary  in  num- 
ber from  three  to  five,  but  there  are  usually  four. 
These  varieties  depend  either  upon  the  greater  or 
less  size  of  the  ilio-lumbar  artery,  which  bears  the 
same  relation  to  the  lumbar  arteries  as  the  superior 
intercostal  does  to  the  aortic  intercostals,  and 
which  sometimes  takes  the  place  of  the  last,  some- 
times of  the  last  two  lumbar  arteries  ;  or  the  va- 
rieties may  depend  on  several  lumbar  arteries  ari- 
sing from  a  common  trunk. 

Origin. — The  lumbar  arteries  are  given  off  at 
right  angles  from  the  back  of  the  aorta.  Very 
rarely  the  right  lumbar  arteries  arise  by  a  common 
trunk  with  the  left. 

Course.  —  They  proceed  transversely  in  the 
grooves  on  the  bodies  of  the  vertebrae,  and  pass 


THE    INFERIOR   PHRENIC   ARTERIES,  ETC.  507 

under  the  tendinous  arches  of  the  psoas,  by  which  muscle  they  are  covered.  They  send 
a  great  number  of  branches  to  the  bodies  of  the  vertebrae  ;  and  having  reached  the  base 
of  the  transverse  processes,  each  of  them  divides  into  tvt^o  branches,  a  posterior  or  dar- 
n-spinal, and  an  anterior  or  abdominal  branch. 

The  posterior  branch,  which  is  analogous  to  the  dorsi-spinal  of  an  intercostal  artery,  di- 
vides into  two  branches  :  one,  the  spinal,  which  enters  the  spinal  canal  through  the  in- 
ter-vertebral foramen,  and  subdivides  into  a  vertebral  branch  for  the  body  of  the  vertebra, 
and  a  medullary  branch  for  the  cord  and  its  coverings  ;  the  other  branch  is  the  dorsal, 
which  terminates  in  the  muscles  and  integuments  of  the  lumbar  region. 

The  antericrr  branch  is  smaller,  and  analogous  to  the  anterior  branch  of  an  intercostal 
artery  :  it  is  situated  between  the  quadratus  lumborum  and  the  middle  layer  of  the  apo- 
neurosis of  the  transversalis,  and  ramifies  in  the  substance  of  the  abdominal  muscles. 
The  anterior  branch  of  the  first  lumbar  artery  runs  along  the  lower  border  of  the  twelfth 
rib,  passes  obUquely  downward  and  forward,  and  divides  into  two  ramuscuU,  one  of  which 
continues  in  the  same  course,  while  the  other  turns  downward  to  the  crest  of  the  ihum. 
The  anterior  branches  of  the  second  and  third  pair  of  lumbar  arteries  are  generally  small : 
not  unfrequently  the  third  artery  is  wanting.  The  anterior  branch  of  the  fourth  lumbar 
artery  runs  along  the  crest  of  the  ilium,  and  sends  branches  to  the  muscles  of  the  abdo- 
men and  to  the  iUacus  and  glutaei  muscles. 

The  Inferior  Phrenic  Arteries. 

Dissection. — Careful.y  detach  the  peritoneum  from  the  lower  surface  of  the  diaphragm. 

The  inferior  phrenic  or  diaphragmatic,  or  the  sub-diaphragmatic  arteries  {d  d.  Jig.  199),  so 
named  in  contradistinction  to  the  superior  phrenic,  which  are  branches  of  the  internal 
mammary,  are  so  frequently  derived  from  the  coeliac  axis,  that  some  anatomists,  Meckel 
among  others,  describe  them  as  branches  of  that  trunk.  They  are  two  in  number,  a 
right  and  a  left.  They  arise  from  the  aorta,  immediately  below  the  cordiform  tendon  of 
the  diaphragm,  either  side  by  side,  or  by  a  common  trunk.  Sometimes  they  arise  from 
the  coeliac  axis  itself,  or,  rather,  from  the  coronary  artery  of  the  stomach,  from  the  renalj 
or  from  the  first  lumbar  artery  ;  in  some  subjects  we  find  as  many  as  three  or  four. 

Each  artery  passes  upward  and  outward  in  front  of  the  corresponding  pillar  of  the  dia- 
phragm, gives  some  twigs  to  this  pillar,  and  one  to  the  supra-renal  capsule,  and  then  di- 
vides into  two  branches,  an  internal  and  an  external.  The  internal  branch  passes  direct- 
ly forward,  ramifies  and  anastomoses  by  loops  with  the  vessel  of  the  opposite  side  around 
the  oesophageal  opening,  behind  the  cordiform  tendon  of  the  diaphragm.  The  exteriial 
branch  is  larger  and  more  tortuous  than  the  preceding ;  it  proceeds  obliquely  outward, 
between  the  peritoneum  and  the  diaphragm,  and  divides  into  a  great  number  of  branches, 
which  extend  as  far  as  the  attachments  of  this  muscle,  where  they  anastomose  with  the 
intercostal  and  the  internal  mammary  arteries. 

The  right  inferior  phrenic  artery,  moreover,  sends  some  branches  into  the  coronary 
ligament  of  the  liver  ;  the  left  artery  gives  off  a  branch  to  the  oesophagus,  which  enters 
through  the  oesophageal  opening  in  the  diaphragm,  and  joins  the  oesophageal  branches 
derived  from  the  coronary  artery  of  the  stomach  and  from  the  aorta. 

The  Cceliac  Axis, 

Dissection. — Elevate  the  liver  by  means  of  hooks,  or  by  a  ligature  fixed  to  the  right 
side  of  the  chest ;  depress  the  stomach  ;  divide  the  fold  of  peritoneum  by  which  these 
two  viscera  are  united ;  and  search  for  the  coeliac  axis  between  the  pillars  of  the  dia- 
phragm, by  removing  the  solar  plexus  of  nerves,  which  forms  a  thick  layer  in  front  of  it. 

The  caliac  axis  or  artery  (from  KoiXia,  the  belly  or  stomach,  y,  fig.  199),  le  tronc  opis- 
thogastrique,  Chauss.  {oTTiadev,  behind,  yaarrip,  the  stomach),  supplies  the  stomach,  the 
liver,  the  spleen,  the  pancreas,  and  the  great  omentum.  It  is  remarkable  for  its  size, 
being  larger  than  any  of  the  other  branches  of  the  abdominal  aorta,  not  excepting  the 
superior  mesenteric ;  for  arising  at  a  right  angle  from  the  front  of  the  aorta,  immediate- 
ly below  the  phrenic  arteries ;  for  its  horizontal  course,  which  is  rarely  more  than  five 
or  six  lines  in  extent,  and  for  its  very  early  division  into  three  branches,  ad  modum  tri- 
dentis.  These  three  branches  are  of  unequal  size  :  they  are  the  coronary  artery  of  the 
stomach  {b,  fig.  200),  the  hepatic  (c),  and  the  splenic  (d),  which,  together,  are  called  the 
caliac  tripos,  or  the  tripos  of  Holler. 

In  its  short  course  the  coeliac  axis  is  in  relation  with  the  lesser  curvature  of  the  stom- 
ach, or,  rather,  with  the  gastro-hepatic  omentum,  behind  which  it  is  situated  ;  on  the 
left  side,  it  is  in  relation  with  the  cardia  ;  below,  with  the  upper  border  of  the  pancreas, 
upon  which  it  rests  ;  above,  with  the  left  side  of  the  lobulus  Spigelii.  It  is  surrounded 
by  so  large  a  plexus  of  nerves,  that  it  cannot  be  exposed  until  the  plexus  is  removed. 

The  Coronary  Artery  of  the  Stomach. 
The  coronary  artery  of  the  stomach,  or  the  superior  gastric  {b,figs.  200, 201),  is  the  small- 
est branch  of  the  coeliac  axis.     It  is  directed  upward  and  to  the  left  side,  to  reach  the 
(Esophageal  orifice  of  the  stomach  ;  it  then  turns  suddenly  to  the  right  side,  pursues  a 


90i 


ANGEIOLOGY. 


Fig.  200. 


semicircular  course  along  the  lesser  curvature 
(arteria  coronaria  ventriculi),  and  terminates  by  in 
osculating  with  the  pyloric  artery  (e),  a  branch 
from  the  hepatic. 

In  this  course  it  gives  off  from  its  convex  bor- 
der ascending  (esophageal  branches,  which  peiss 
through  the  (Esophageal  opening  of  the  dia- 
phragm, ascend  upon  the  oesophagus,  and  are 
there  distributed  like  the  aortic  oesophageal 
branches,  with  which  they  anastomose  ;  also  car- 
diac branches,  which  form  a  vascular  network 
around  the  oesophageal  opening  of  the  stomach, 
and  pass  transversely  upon  its  great  tuberosity  ; 
and  a  series  o(  gastric  branches,  which  arise  along 
the  lesser  curvature,  and  are  divided  into  two 
sets,  an  anterior  set  for  the  front,  and  a  posterior 
set  for  the  back  of  the  stomach.  No  branch  ari- 
ses from  the  concavity  of  the  curve  formed  by 
this  artery. 

Not  unfrequently  the  coronary  artery  of  the 
stomach  gives  off  an  hepatic  branch,  and  hence 
the  first  branch  of  the  coeliac  axis  has  been  called 
the  gastro-hepatic  by  some  anatomists.  In  such 
cases,  as  may  be  conceived,  this  artery  is  very 
large.  It  is  also  not  uncommon  to  find  the  left 
inferior  phrenic  arising  from  it. 


The  Hepatic  Artery. 

The  hepatic  artery  (c,  Jigs.  200,  201)  is  larger  than  the  preceding.  It  passes  trans- 
versely from  the  left  to  the  right  side,  describing  a  curve,  having  its  concavity  directed 
upward,  and  moulded,  as  it  were,  upon  the  lobulus  Spigelii.  Near  the  pylorus  it  chan- 
ges its  direction,  and  passes  upward  to  the  transverse  fissure  of  the  liver,  where  it  di- 
vides into  two  branches.  In  the  latter  part  of  its  course  it  is  contained  within  the  gas- 
tro-hepatic omentum,  in  front  of  the  foramen  of  Winslow,  and  is  in  relation  with  the 
ductus  choledochus  and  the  vena  portse,  the  vein  being  placed  behind  both  the  artery 
and  duct. 

It  is  not  uncommon  to  find  two  hepatic  arteries,  one  derived  from  the  coronary  of  the 
stomach,  and  the  other  from  the  superior  mesenteric.  Sometimes  there  are  even  three 
hepatic  arteries,  one  from  the  coronary  of  the  stomach,  a  second  from  the  superior  mes- 
snteric,  and  a  third  from  the  coeliac  axis. 

Collateral  Branches. — The  hepatic  artery  gives  off  three  collateral  braiiihes,  the  pylo- 
ric, the  right  gastro-epiploic,  and  the  cystic. 

The  pyloric  artery,  also  named  the  small  right  gastric  artery,  to  distinguish  it  from  the 
coronary  artery  of  the  stomach,  which  was  called  the  left  gastric  (c),  is  a  small  vessel 
which  arises  from  the  hepatic,  near  the  pylorus  :  it  runs  from  right  to  left  along  the 
pylorus  and  the  lesser  curvature  of  the  stomach,  and  inosculates  with  the  coronary  ar- 
tery (6)  of  that  viscus.  Two  sets  of  branches,  an  anterior  and  a  posterior,  arise  from 
its  convex  border,  and  are  distributed  to  the  stomach  and  the  first  part  of  the  duodenum, 
in  the  same  manner  as  those  from  the  coronaria  ventriculi  itself  Not  unfrequently  the 
pyloric  artery  terminates  near  the  pylorus,  without  anastomosing  with  the  coronary. 

T\ie  right  gastro-epiploic  artery  (f,figs.  200,  201)  is  remarkable  for  its  size  and  for  its 
length.  It  passes  vertically  downward,  behind  the  first  portion  of  the  duodenum,  near 
the  pylorus.  Having  reached  below  the  duodenum,  it  changes  its  direction,  passes  from 
right  to  left  (Z)  along  the  great  curvature  of  the  stomach,  where  it  inosculates  with  the 
left  gastro-epiploic  {h,  fig.  201).  In  one  case,  where  the  hepatic  artery  was  given  off 
by  the  superior  mesenteric,  the  right  gastro-epiploic  arose  directly  from  the  coeliac  axis. 

The  first  portion  of  this  vessel,  usually  called  the  gastro-duodenal  artery,  furnishes  sev- 
eral branches  to  the  pylorus,  which  may  be  called  the  inferior  pyloric ;  it  then  gives  a 
branch  to  the  duodenum  and  the  head  of  the  pancreas,  named  the  pamreatico-duodena- 
lis  (k),  and  remarkable  for  its  anastomosing  with  the  superior  mesenteric  ;  an  arrange- 
ment that  leads,  as  it  were,  to  the  cases  in  which  the  hepatic  itself  is  derived  from  the 
last-mentioned  artery  ;  it  is  also  remarkable  for  its  size,  which  is  sometimes  such  that 
the  continuation  of  the  vessel,  the  right  gastro-epiploic  artery  proper,  is  only  half  the 
size  of  the  trunk  from  which  it  is  given  off  (the  gastro-duodenal). 

In  its  horizontal  portion  along  the  great  curvature  of  the  stomach,  the  right  gastro- 
epiploic sends  both  ascending  and  descending  branches  :  the  former,  or  gastric  branches, 
divide  into  two  sets  ;  one  for  the  anterior,  and  one  for  the  posterior  surface  of  the  stom- 
ach    The  latter,  or  epiploic  branches  (g  g,  fig.  200J,  are  extremely  long  and  slender ; 


THE   SPLENIC   AND   SUPERIOR   MESENTERIC    ARTERIES.  509 

they  pass  downward  parallel  to  each  other,  without  any  windings,  in  the  substance  of 
the  two  anterior  layers  of  the  great  omentum,  are  reflected  upward  at  its  lower  border, 
just  as  the  two  layers  are  themselves,  and  accompany  them  as  far  as  the  transverse 
colon,  to  which  they  are  distributed. 

The  cystic  artery  (i,  fig.  200)  is  a  small  vessel  which  almost  always  arises  from  the 
right  of  the  terminal  divisions  of  the  hepatic  artery,  reaches  the  neck  of  the  gall-blad- 
der, and  divides  into  two  branches ;  one  superior,  running  between  the  liver  and  the 
vesicula,  the  other  inferior,  which  pursues  a  tortuous  course  between  the  peritoneum 
and  the  proper  coat  of  the  gall-bladder,  divides  and  subdivides,  and  is  finally  distributed 
to  the  mucous  membrane. 

Termhial  Branches. — Of  the  two  terminal  branches  of  the  hepatic  artery,  one  dips  into 
the  right  extremity  of  the  transverse  fissure  of  the  liver,  and  the  other  into  the  left  ex- 
tremity of  the  same  fissure  :  in  these  situations  they  become  applied  to  the  correspond- 
ing branches  of  the  vena  portae  and  hepatic  duct,  are  enclosed  with  them  in  the  capsule 
of  Glisson,  and  closely  accompany  the  corresponding  ramifications  of  those  vessels 
through  all  their  divisions  and  subdivisions. 

The  Splenic  Artery. 

The  sflenic  artery  {d,  figs.  200,  201)  is  larger  Fig.  ZOi. 

than  either  of  the  other  divisions  of  the  cceliac 
axis.  Immediately  after  its  origin  it  is  received 
into  a  shght  groove  formed  along  the  whole  of  the 
upper  border  of  the  pancreas  (i).  It  passes  from 
the  right  to  the  left  side,  and  is  exceedingly  tor- 
tuous in  its  course  :*  having  reached  the  hilus 
of  the  spleen,  it  divides  into  a  great  number  of 
terminal  branches  (w,  fig.  201),  which  enter  that 
organ  separately.  It  is  not  rare  to  find  one  of 
these  branches  detached  from  the  others,  to  be 
distributed  either  to  the  upper  or  the  lower  end 
of  the  spleen. 

Near  the  spleen,  the  splenic  artery  and  its  di- 
visions are  enclosed  within  the  gastro-splenic  omentum. 

The  relations  of  the  splenic  artery  to  the  posterior  surface  of  the  stomach  explains 
how,  in  certain  cases  of  ulceration  of  the  stomach  opposite  the  pancreas,  this  artery 
may  become  the  source  of  haematemesis. 

The  splenic  artery  gives  off  several  collateral  branches  : 

The  pancreatic  arteries  (i  i),  which  are  variable  in  number,  and  are  very  large,  consid- 
ering the  size  of  the  organ  to  which  they  are  distributed. 

The  left  gastro-epiploic  artery  (h),  which  often  arises  from  one  of  the  divisions  of  the 
splenic,  passes  vertically  downward,  behind  the  great  end  of  the  stomach,  gains  the 
great  curvature,  along  which  it  runs  from  left  to  right,  and  anastomoses  with  a  branch 
of  the  hepatic,  viz.,  the  right  gastro-epiploic  (l) ;  like  which  artery,  it  sends  off  ascending 
or  gastric,  and  descending  or  epiploic  branches.  The  size  of  the  gastro-epiploica  sinistra 
varies  much,  and  has  an  inverse  proportion  to  that  of  the  gastro-epiploica  dextra. 

The  vasa  brevia  (o  o),  which  are  remarkable  for  their  number  and  shortness,  generally 
arise  from  one  or  several  of  the  terminal  branches  of  the  splenic  artery,  just  as  these 
are  entering  the  spleen  ;  they  pass  directly,  by  a  retrograde  course,  from  that  organ  to 
the  great  cul-de-sac  of  the  stomach,  as  far  as  the  cardia,  where  they  anastomose  with 
the  cardiac  branches  of  the  coronary  artery  of  the  stomach. 

From  the  preceding  description  of  the  branches  of  the  cceliac  axis,  we  perceive  that 
the  stomach  is  surrounded  by  an  uninterrupted  arterial  circle,  formed  by  the  right  and 
left  gastro-epiploic,  by  the  pyloric,  and  by  the  coronary  arteries  ;  and  that,  secondly,  the 
branches  derived  from  this  circle  constitute  an  anastomotic  network  upon  the  anterior 
and  posterior  surfaces  of  the  stomach. 

The  Superior  Mesenteric  Artery. 

Dissection. — Look  for  the  origin  of  the  artery  between  the  pancreas  and  the  third  por- 
tion of  the  duodenum ;  turn  the  whole  of  the  small  intestines  to  the  left  side  ;  remove 
with  care  the  right  layer  of  the  mesentery,  the  left  layer  of  the  right  lumbar  mesocolon, 
the  inferior  layer  of  the  transverse  mesocolon,  and  the  numerous  lymphatic  glands  which 
conceal  the  artery  and  its  divisions. 

The  superior  mesenteric  artery  (below  y,fig.  199)  is  the  artery  of  the  small  intestine, 
and  of  the  right  half  of  the  large  intestine.     It  arises  from  the  front  of  the  aorta,  imme- 

*  I  have  seen  some  splenic  arteries  not  at  all  tortuous  ;  and  at  other  times  I  hare  found  the  curvatures  so 
decided  that  the  lower  part  only  of  the  curves  came  in  contact  with  the  pancreas.  Why  do  these  curvatures 
exist  ?  It  cannot  be  to  accommodate  the  variations  in  the  size  of  the  spleen  ;  but  is  it  to  retard  the  now  ol 
the  blood  ?  There  is  no  proof  of  it ;  indeed,  the  law  which  governs  the  existence  of  a  tortuous  condition  ol 
certain  arteries  is  yet  to  he  discovered.  The  caliber  of  the  splenic  artery  is  strictly  proportioned  to  the  size 
of  the  spleen.    Where  it  is  strophied  the  artery  is  small  ■  where  hypertrophied,  it  becomes  enormously  enlarged 


ANGEIOLOGY. 


diately  below  the  coeliac  axis,  and  very  rarely  from  a  common  trunk  with  it.  It  is  at 
first  situated  behind  the  pancreas,  and  then  passes  vertically  downward,  between  that 
gland  and  the  third  portion  of  the  duodenum,  which  is  crossed  at  right  angles  by  it, 
and  of  which  it  forms  the  lower  boundary  {vide  Duodenum)  ;  it  at  length  reaches  the 

mesentery,  opposite  the  point  (a,  fig.  202) 
where  that  fold  meets  the  transverse  meso- 
colon. Continuing  its  course  within  the  sub 
stance  of  the  mesentery,  and  following  its  ad- 
herent border,  it  describes  a  slight  curve,  with 
the  convexity  directed  to  the  left  and  the  con- 
cavity to  the  right  side :  gradually  diminish- 
ing in  size  as  it  advances,  it  proceeds  to  oppo- 
site the  ileo-caecal  valve  (i),  and  then  becomes 
so  small  that  it  can  no  longer  be  distinguished 
from  the  branches  given  off  from  it.  It  fol- 
lows, therefore,  that  the  trunk  (a  b)  of  the  su- 
perior mesenteric  artery  corresponds  with  the 
adherent  border  of  the  mesentery,  with  the 
length  of  which  it,  as  it  were,  agrees. 

Collateral  Branches. — While  behind  the  pan- 
creas, the  superior  mesenteric  sends  off  pan- 
creatic branches  {k),  which  anastomose  with 
those  derived  from  the  hepatic  and  the  splenic 
arteries  ;  it  rather  frequently  gives  off  the  he- 
patic, and  it  is  then  larger  than  the  coeliac 
axis. 

In  the  mesentery,  the  superior  mesenteric 
gives  off  two  sets  of  branches  :   one  set  ari 
sing  from  its  convexity,  and  forming  the  arter- 
ies of  the  small  intestine ;  the  other  set  from  its 
concavity,  viz.,  the  arteries  of  the  great  intestine,  called  the  right  colic  arteries. 

The  arteries  of  the  small  intestine  have  received  no  particular  name  ;  they  are  large 
branches,  directed  obliquely  downward  and  forward,  all  of  which  proceed  parallel  to 
each  other  in  the  substance  of  the  mesentery,  towards  the  concave  border  of  the  small 
intestine.  Their  number  is  irregular,  and  their  size  unequal :  seven  or  eight  of  them 
are  at  least  equal  in  size  to  the  radial  artery,  others  are  smaller ;  the  superior  branches 
are  generally  the  largest.     Their  number  is  calculated  at  from  fifteen  to  twenty. 

After  a  course  of  about  two  or  three  inches,  each  of  them  bifurcates  ;  the  branches 
of  the  bifurcation  separate  from  each  other,  and,  curving  into  arches,  inosculate  with 
the  neighbouring  branches.  From  the  convexity  of  this  series  of  arches,  which  is  turn- 
ed towards  the  intestine,  a  multitude  of  branches  arise,  which  soon  bifurcate,  and  form 
anastomotic  arches  {d  d  d),  which,  as  they  are  nearer  the  small  intestine,  describe  a 
curve  of  much  greater  extent  in  the  mesentery  than  the  first  series.  From  the  con- 
vexity of  this  second  series  of  arches  a  great  many  more  branches  arise  than  were  given 
off  from  the  first  series.  Lastly,  from  the  division  of  these  branches  a  third  series  of 
anastomotic  arches  is  formed,  which  is  still  nearer  the  concave  border  of  the  intestine 
than  the  second. 

There  are  only  three  series  of  arches  at  the  commencement  and  the  termination  of 
the  small  intestine ;  but  in  the  middle  there  is  a  fourth,  sometimes  even  a  fifth. 

From  the  convexity  of  the  arches  nearest  to  the  small  intestine  arise  two  sets  of  ves- 
sels, intended  for  the  two  halves  of  the  cylindrical  gut.  Each  of  these  sets  of  vessels 
divides  into  superficial  branches,  which,  ramifying  beneath  the  peritoneum,  form  a  super- 
ficial network,  and  anastomose  upon  the  convex  border  of  the  intestine  ;  and  into  deep 
branches,  which  perforate  in  succession  the  muscular  and  cellular  coats,  and  terminate 
in  an  inextricable  network  in  the  mucous  membrane. 

The  series  of  anastomotic  arches  formed  by  the  divisions  of  the  superior  mesenteric 
artery,  not  only  regulate  the  current  of  the  blood,  but  also  enable  a  small  number  of 
branches,  occupying  a  very  Umited  space  at  the  root  of  the  mesentery,  to  supply  branches 
to  so  great  an  extent  of  surface  as  the  entire  length  of  the  small  intestine,  which  is  from 
fifteen  to  twenty-one  feet.  This  spreading  out  of  the  vessels  over  a  large  surface  will 
be  still  better  seen  in  the  arrangement  of  the  arteries  of  the  great  intestine. 

The  arteries  for  the  great  intestine,  or  the  right  colic  arteries,  are  two  or  three  in  num- 
ber, and  are  distinguished  into  the  superior  (e),  middle  (/),  and  inferior  (A).  They  arise 
from  the  concavity  of  the  curve  formed  by  the  superior  mesenteric  artery,  and  pass  from 
the  mesentery,  in  which  they  are  enclosed  at  their  origin,  into  the  right  lumbar  meso- 
colon. The  superior  is  ascending,  the  middle  horizontal,  and  the  inferior  descending ; 
near  the  great  intestine  they  bifurcate.  The  branches  of  the  bifurcation  anastomose, 
and  form  very  large  arches,  with  their  convexities  turned  towards  the  great  intestine. 
From  these  arches  the  intestinal  branches  take  their  origin  directly,  and  divide  into  two 


m 


THE    INFERIOR    MESENTERIC    ARTERY,    ETC. 


511 


Fig.  203. 


sets  of  parallel  ramifications,  an  anterior  and  a  posterior,  which,  like  those  of  the  small 
intestine,  subdivide  into  the  sub-peritoneal  and  the  deep  branches,  and  terminate  in  the 
different  coats  of  the  intestine.  Where  the  primary  anastomotic  arches  are  situated  at 
a  certain  distance  from  the  intestine,  for  example,  opposite  the  angles  of  bifurcation  of 
the  arteries,  or  opposite  the  angles  formed  by  the  ileum  with  the  caecum,  and  by  the  as 
cending  with  the  transverse  colon,  we  find  one,  or  even  two,  small  arches  filling  up  the 
angular  interval. 

The  upper  branch  (g)  of  the  right  superior  colic  artery  (e,  figs.  202,  203),  which  sup- 
plies the  right  half  of  the  arch  of  the  colon,  anastomoses  with  the  upper  branch  of  the 
left  colic  artery  Cf^fig-  203),  which  is  derived  from  the  inferior  mesenteric  (c).  This  re- 
markable anastomosis  between  the  superior  and  inferior  mesenteric  arteries  has  been 
pointed  out  by  anatomists  as  the  most  important  anastomosis  in  the  body. 

The  lowest  branch  of  the  right  inferior  colic  artery  (A,  fig.  202)  anastomoses  with  the 
termination  (J)  of  the  superior  mesenteric,  which  becomes  exceedingly  slender.  This 
right  inferior  colic,  or  ileo-colic  artery  (h),  supplies  the  caecum,  the  ileo-caecal  angle,  and 
the  appendix  vermiformis. 

The  Omphalo-mcsenteric  Artery. — In  the  early  periods  of  intra-uterine  life,  the  superior 
mesenteric  artery  gives  off  a  branch,  called  the  omphalo-mesentenc,  which  reaches  the 
umbilicus,  passes  out  of  the  abdomen,  traverses  the  entire  length  of  the  cord,  and  is  dis- 
tributed upon  the  umbilical  vesicle.  I  have  found  this  artery  perfectly  distinct  in  an 
anencephalous  fcEtus  at  the  full  term ;  it  is  generally  obliterated  towards  the  end  of  the 
second  month  of  intra-uterine  life. 

The  Inferior  Mesenteric  .Artery. 

Dissection. — Turn  the  small  intestines  to  the  right  side  ;  spread  out  the  arch  of  the 
colon,  the  right  lumbar  colon,  and  the  sigmoid  flexure ;  remove  the  peritoneum,  which 
forms  the  inferior  layer  of  the  transverse  mesocolon,  and  the  right  layer  belonging  to  the 
descending  colon  and  sigmoid  flexure. 

The  inferior  mesenteric  artery  (m,fig.  199  ;  c,fig.  203)  is  much  smaller  than  the  supe- 
rior. It  arises  from  the  front"  of  the  aorta,  about 
two  inches  above  the  bifurcation  of  that  vessel. 
It  descends  vertically  in  front  of,  and  in  contact 
with  the  aorta,  and  then  in  front  of  the  left  com- 
mon iliac  artery.  It  is  at  first  enclosed  in  the  ili- 
ac mesocolon,  but  afterward  enters  the  meso-rec- 
tum,  where  it  divides  into  two  branches,  which 
are  named  the  superior  hemorrhoidal  {h,  fig.  203). 
In  this  course,  the  inferior  mesenteric  gives  off 
no  branch  on  the  right  side  ;  on  the  left  it  gives 
two,  more  frequently  three  branches,  called  the 
left  colic  arteries  (/),  which  are  distributed  in  pre- 
cisely the  same  manner  as  the  right  colic  arteries. 
I  have  already  said  that  the  upper  division  of  the 
left  superior  colic  artery  (/)  inosculates  with  the 
upper  division  (g)  of  the  right  superior  colic  (c). 
Near  the  sigmoid  flexure  we  find  two,  and  some- 
times three  series  of  arches  from  the  sigmoid 
branch,  so  arranged  that  the  last  may  reach  the 
intestine. 

The  superior  hemorrhoidal  arteries  are  distribu- 
ted to  the  rectum,  in  the  same  manner  as  the  other 
intestinal  arteries ;  near  the  sphincter,  they  anas- 
tomose with  the  middle  hemorrhoidals,  which 
are  derived  from  the  internal  iliac  arteries. 

The  Spermatic  Arteries — the  Arteries  of  the  Testicles  in  Man,  and  the  Utero- 

ovarien  in  Woman. 

Dissection. — Remove  carefully  the  mesentery  and  the  peritoneum.  Follow  these  ar- 
teries, in  man,  through  the  inguinal  passages  imbedded  in  the  substance  of  the  sper- 
matic cord,  down  to  the  testicle  and  the  epididymis  ;  and  in  woman,  follow  them  into  the 
substance  of  the  broad  ligament  as  far  as  the  ovaries  on  one  side,  and  on  the  other,  as 
far  as  the  bottom  and  the  body  of  the  uterus.  To  inject  perfectly  these  arteries  to  their 
termination,  recourse  must  be  had  to  very  penetrating  liquids,  or,  what  is  better,  to  par- 
tial injections. 

The  spermatic  arteries  (o  o,fig.  198  ;  ff,fig.  199)  are  distributed  to  the  testicles  in  the 
male,  and  to  the  ovaries  in  the  female. 

They  are  two  in  number,  and  are  as  variable  in  their  origin  as  they  are  regular  in  their 
course  and  distribution. 

Their  origin  is  remarkably  distant  from  their  termination ;  an  unsatisfactory  attempt 


® 


612  ANGEIOLOGY. 

has  been  made  to  explain  this  circumstance  by  referring  to  the  situation  of  the  testicle  in 
the  foetus. 

Varieties  of  Origin. — These  arteries  generally  arise  from  the  front,  sometimes  from 
the  side  of  the  aorta,  below  the  corresponding  renal  artery,  rarely  above  it,  and  still 
more  rarely  from  the  renal  itself  It  is  rather  rare  for  the  right  and  left  spermatics  to 
come  off  at  the  same  heights.  I  have  seen  the  right  spermatic  artery  arise  below  the 
renal,  and  the  left  by  the  side  of  the  inferior  mesenteric* 

Whatever  may  be  their  origin,  these  arteries  pass  directly  downward.  Sometimes 
they  come  off  at  a  riglit  angle,  and  then  curve  downward,  so  as  to  descend  almost  ver- 
tically upon  the  sides  of  the  spine,  behind  the  peritoneum,  in  front  of  the  corresponding 
psoas  muscle  and  ureter,  and  on  the  inner  side  of  the  spermatic  veins.  The  right  sper- 
matic artery  is  in  relation  with  the  vena  cava  inferior,  and  almost  always  passes  in  front, 
but  sometimes  behind  it ;  the  artery  of  the  left  side  is  situated  behind  the  sigmoid  flex- 
ure of  the  colon.  On  both  sides,  having  reached  the  side  of  the  pelvis,  the  artery  is  sit- 
uated on  the  inner  side  of  the  psoas,  in  front  of  the  external  iliac  artery,  and  is  then  dif- 
ferently distributed  in  the  two  sexes. 

Li  the  male  {f,  fig-  199),  it  enters  the  abdominal  orifice  of  the  inguinal  canal,  along 
which  it  proceeds,  and,  together  with  the  vas  deferens  and  the  spermatic  veins,  forms  the 
spermatic  cord ;  it  escapes  from  the  canal,  and,  at  a  greater  or  less  distance  from  the 
ring,  divides  into  two  branches,  one  of  which  enters  the  head  of  the  epididymis,  while 
the  other,  the  testicular,  penetrates  the  testicle  at  its  upper  border,  and  is  then  distribu- 
ted as  already  described  (see  Testicles). 

In  the  female,  the  ovarian  arteries  (o  o,fig.  198),  which  are  much  shorter  than  the 
spermatics  of  the  male,  dip  into  the  pelvis,  reach  the  upper  border  of  the  ovaries,  supply 
them,  and  also  the  Fallopian  tubes,  with  a  great  number  of  branches,  and  terminate 
upon  the  sides  of  the  uterus,  by  anastomosing  freely  with  the  uterine  arteries  («  w').+ 

The  ovarian  arteries  are  distributed  more  to  the  uterus  than  to  the  ovary,  as  may  be 
proved  by  the  post  mortem  examination  of  the  body  of  a  pregnant  or  puerperal  female  ; 
for  it  is  then  seen  that  the  ovarian  arteries  also  become  largely  developed  as  well  as  the 
uterine,  and  that  the  branches  sent  to  the  uterus  are  enormous  in  comparison  with  those 
given  off  to  the  ovaries. 

The  ovarian  arteries  are  very  tortuous,  especially  opposite  the  brim  of  the  pelvis ; 
they  are  quite  as  much  convoluted  as  the  uterine  arteries. 

The  Renal  or  Emulgent  Arteries. 

Dissection. — The  renal  arteries  are  prepared  after  the  intestines,  the  peritoneum,  the 
renal  adipose  tissue,  and  the  numerous  nervous  filaments  by  which  the  arteries  are  sur- 
rounded, have  been  removed. 

The  renal  or  emulgent  arteries  {,e  e,fig.  199)  arise  at  right  angles  from  the  side  of  the 
aorta,  above  the  inferior  mesenteric  :  the  left  renal  artery  often  arises  a  little  higher 
than  the  right,  doubtless  on  account  of  the  size  of  the  liver.  These  arteries  are  very 
large  in  comparison  to  the  kidney,  for  they  are  nearly  equal  in  size  to  the  cceliac  axis, 
or  the  superior  mesenteric ;  they  are  remarkable  for  their  transverse,  and,  generally, 
straight  direction  ;  for  their  shortness ;  and,  lastly,  for  their  numerous  varieties.  These 
we  shall  now  mention. 

Varieties  as  to  Number. — There  is  generally  one  for  each  kidney,  but  frequently  there 
are  two,  three,  or  four.  Varieties  as  to  Origin. — Not  uncommonly  the  renal  arteries  arise 
from  the  aorta  lower  down  than  usual,  or  even  from  the  common  iliac  or  the  internal 
iliac.  The  two  latter  modes  of  origin  are  scarcely  observed,  excepting  when  the  kidney 
is  displaced,  and  occupies  either  the  ihac  fossa  or  the  cavity  of  the  pelvis.  In  a  case 
which  I  recently  examined,  the  kidney  occupied  the  cavity  of  the  pelvis,  and  there  were 
two  renal  arteries,  one  of  which  arose  from  the  aorta  at  its  bifurcation,  and  the  other 
near  the  inferior  mesenteric.  Lastly,  I  should  add  that  Meckel  has  seen  the  two  renal 
arteries  arise  by  a  common  trunk  from  the  front  of  the  aorta.  Varieties  in  Direction.— 
When  two  renal  arteries  arise  from  the  same  side,  or  when  one  divides  into  two  branch- 
es, I  have  found  them,  in  several  cases,  twisted  spirally  round  each  other,  like  the  um- 
bilical arteries.  Varieties  as  to  Division. — The  renal  artery  sometimes  divides  immedi- 
ately after  its  origin  ;  and  then  one  of  the  branches,  separating  itself  from  the  others, 
proceeds  to  one  or  other  extremity  of  the  kidney.  Such  a  mode  of  division  leads  to 
those  cases  in  which  there  is  more  than  one  artery. 

Relations. — The  renal  arteries  are  covered  by  the  peritoneum  and  the  corresponding 
renal  veins  ;  they  are  surrounded  by  a  quantity  of  adipose  cellular  tissue,  and  they  rest 
behind  upon  the  bodies  of  the  vertebrae.  The  right  renal  artery  is  also  covered  by  the 
inferior  vena  cava.  In  one  case,  where  there  were  two  renal  arteries  on  the  right  side, 
one  of  these  was  in  front,  and  the  other  behind  the  vena  cava. 

*  It  IS  not  micommon  to  meet  witn  two  spermatic  artenes  on  one  siae 

t  We  know  that  the  development  of  the  uterus,  (luring  the  first  five  months  a&  pregnancy,  takes  place  al- 
most exclusively  at  the  expense  of  the  body,  and  that  the  neck  of  the  uterus  be^ns  to  be  developed  from  the 
fifth  to  the  sixtii  month.  I  have  seen  some  diseases  of  the  uterus  in  which  a  sort  of  independence  might  have 
been  traced  between  the  neck  and  the  body  of  the  womb. 


THE    CAPSULAR    ARTERIES,  ETC.  618 

Collateral  Branches. — The  renal  arteries  give  off  some  small  twigs  to  the  supra-renal 
capsules,  which  are  called  the  inferior  capsular  or  supra-renal,  and  also  some  small  branch- 
es to  the  adipose  tissue  which  covers  the  kidney,  and  to  its  proper  cellular  coat. 

Terminal  Branches. — At  the  hilus  of  the  kidney,  the  renal  artery  divides  into  three  or 
tour  branches,  all  of  which  enter  the  hilus,  between  the  pelvis  of  the  ureter,  which  is 
behind,  and  the  branches  of  the  renal  vein,  which  are  in  front.  The  arteries  subdivide 
in  the  kidney  so  as  to  form  a  network  at  the  Umits  between  the  tubular  and  cortical  sub- 
stances. (See  Kidney.)  A  very  few  of  the  branches  from  this  network  proceed  to  the 
tubular  substance,  almost  all  of  them  being  distributed  to  the  cortical  substance.  Most 
anatomists  have  remarked  the  facility  with  which  even  coarse  injections  pass  from  the 
renal  arteries  into  the  veins  and  ureters. 

The  Middle  Supra-renal,  or  Capsular  Arteries. 

The  middle  supra-renal  arteries  {s  s,fig.  199),  so  named  in  contradistinction  to  the  supe- 
rior vessels  of  the  same  name,  derived  from  the  diaphragmatic  and  the  inferior,  pro- 
ceeding from  the  renal,  are  of  large  size  in  comparison  with  the  organ  to  which  they  are 
distributed.  They  arise  from  the  sides  of  the  aorta,  above  the  renal,  supply  twigs  to  the 
surrounding  fat,  and  to  the  pillar  of  the  diaphragm,  run  along  the  concave  border  of  the 
corresponding  supra-renal  capsule,  give  off  anterior  and  posterior  branches,  which  enter 
the  furrows  on  the  surface  of  that  organ,  and  penetrate  and  ramify  in  its  interior. 


ARTERIES  ARISING  FROM  THE  ARCH  OF  THE  AORTA. 
Enumeration  and  Varieties. — The  Common  Carotids. — The  External  Carotid — the  Superior 
Thyroid — the  Facial — the  Lingual — the  Occipital — the  Posterior  Auricular — the  Parotid 
— the  Ascending  Pharyngeal — the  Temporal — the  Internal  Maxillary. — The  Internal  Ca- 
rotid— the  Ophthalmic — the  Cerebral  Branches  of  the  Internal  Carotid. — Summary  of  the 
Distribution  of  the  Common  Carotids. — Artery  of  the  Upper  Extremity. — The  Brachio-Ce- 
phalic. — The  Right  and  Left  Subclavian^ — the  Vertebra}  and  its  Cerebral  Branches,  with 
Remarks  on  the  Arteries  of  the  Brain,  Cerebellum,  and  Medulla — the  Inferior  Thyroid — 
the  Supra-scapular — the  Posterior  Scapular — the  Internal  Mammary — the  Deep  Cervical 
— the  Superior  Intercostal. — The  Axillary — the  Acromio-thoracic — the  Long  Thoracic — the 
Sub-scapular — the  Posterior  Circumflex — the  Anterior  Circumflex. — The  Brachial  and  its 
Collateral  Branches. — The  Radial,  its  Collateral  Branches,  and  the  Deep  Palmar  Arch. — 
The  Ulnar,  its  Collateral  Branches,  and  the  Superficial  Palmar  Arch. — General  Remarks 
on  the  Arteries  of  the  Upper  Extremity. 

Three  arterial  trunks,  intended  to  supply  the  head  and  the  upper  extremities,  take 
their  origin  from  the  arch  of  the  aorta.  Proceeding  in  the  order  in  which  they  arise,  i.  e., 
from  right  to  left,  they  are  the  innominate  or  brachio-cephalic  {e,fig.  198),  which  soon  sub- 
divides into  the  right  common  carotid  (/)  and  right  subclavian  (g),  the  left  common  carotid  (f) 
and  the  left  subclavian  (g). 

The  direction  of  that  portion  of  the  arch  of  the  aorta  which  gives  origin  to  these  arter- 
ies is  such,  that  they  are  arranged  one  after  the  other  upon  a  plane  which  slopes  down- 
ward, backward,  and  to  the  left ;  so  that  the  trunk  of  the  innominate  artery  lies  almost 
immediately  behind  the  sternum,  while  the  left  subclavian  is  near  the  vertebral  column. 
Varieties. — These  three  arteries  present  numerous  varieties  in  their  origin,  all  of  which 
appear  to  me  to  be  referrible  to  the  three  following  heads :  varieties  by  approximation  or 
fusion,  varieties  by  multiplication,  and  varieties  by  transposition  of  their  origins.  In 
many  cases,  several  of  these  kinds  of  varieties  may  coexist.* 

Varieties  by  Approximation  or  Fusion  of  Origins. — Sometimes  the  left  common  carotid 
becomes  closely  approximated  to  the  brachio-cephalic  trunk  ;  and  this  condition  leads  us 
to  the  not  very  uncommon  variety  in  which  these  two  vessels  arise  by  a  common  trunk,  t 
Again,  two  brachio-cephalic  trunJjs  may  be  given  off  from  the  arch  of  the  aorta,  one  on 
the  right,  the  other  on  the  left  side.t  Of  these  two  trunks  which  arise  from  the  aorta, 
the  first,  which  is  the  most  voluminous,  gives  origin  to  the  two  carotid  arteries,  and  to 
the  right  subclavian  ;  the  second,  which  is  the  smallest,  gives  origin  to  the  left  subcla- 
vian. The  greatest  amount  of  variety  of  this  kind  is  observed  in  the  case  where  the 
three  branches  which  usually  arise  from  the  arch  are  united  into  one  common  trunk, 
which  forms  an  ascending  aorta.    In  this  case,  there  is  no  arch  of  the  aorta ;  the  aorta, 

*  [A  variety,  affecting  merely  the  situation  of  the  three  primary  vessels  upon  the  arch,  is  noticed  by  Pro- 
fessor R.  Quain  {Operacit.).  It  consists  in  those  vessels  arising  to  the  riglit  of  their  usual  position,  t.  e., near- 
er to  the  origin  of  the  aorta.] 

t  I  have  often  seen  these  three  branches,  viz.,  the  brachio-cephalic  trunk,  the  left  primitive  carotid,  and  the 
left  subclavian,  arising  by  tlie  side  of  each  other,  so  that  their  three  orifices  were  only  separated,  as  it  were, 
by  a  spur. 

i  This  variety,  which,  together  with  the  preceding,  constitutes  the  normal  state  of  some  animals,  seems, 
moreover,  th&  reproduction  of  the  normal  disposition  of  the  venous  system,  in  which  there  are  two  cephalic 
venous  trunks,  one  right,  the  other  left,  which  unite  for  the  purpose  of  forming  the  superior  vena  cava.  Meck- 
el, I  believe,  was  the  first  to  remark  that  certain  anomalies  of  the  arterial  system  might  be  attributed  to  the 
normal  disposition  of  the  venous  system. — (See  the  excellent  article  of  Dr.  Rendu,  Memoir  on  the  History  of 
Arterial  Anomalies,  Gazette  Medicate,  1842,  vol.  x.,  p.  129.) 

Ttt 


514  ANGEIOLOOY. 

immediately  after  its  origin,  is  divided  into  ascending  and  descending.  This  arrange- 
ment is  normal  in  the  ox,  the  horse,  the  sheep,  the  goat,  and  some  other  animals.* 

Varieties  by  Multiplication  of  Origin. — Sometimes  the  two  common  carotids  arise  sep- 
arately in  the  interval  between  a  right  and  a  left  subclavian,  a  condition  that  leads  us  to 
the  case  in  which  the  two  carotids  arise  by  a  common  trunk  between  the  separated  sub- 
clavians.  Again,  the  left  vertebral  artery  may  arise  directly  from  the  aorta,  between 
the  left  carotid  and  subclavian  ;  this  is  very  common :  or  the  two  vertebrals,  the  two 
carotids,  and  the  two  subclavians  may  all  arise  separately  ;  or  the  inferior  thyroid,  or  the 
thyroid  of  Neubauer,  from  the  name  of  the  anatomist  who  first  described  this  variety, 
may  arise  directly  from  the  curvature  of  the  aorta ;  lastly,  the  right  internal  mammary 
and  the  left  vertebral  may  arise  directly  from  the  arch  of  the  aorta. 

Varieties  by  Transposition  or  Inversion  of  Origin. — The  brachio-cephalic  trunk  is  some- 
times found  on  the  left  side  instead  of  the  right ;  still  more  frequently  the  right  subcla- 
vian arises  separately  below  the  left  subclavian,  and  then  passes  upward  and  to  the 
right  side,  most  commonly  behind  the  trachea  and  oesophagus,  but  sometimes  between 
these  two  canals.  Again,  the  trunks  arising  from  the  arch  of  the  aorta  have  been  seen 
to  be  given  off  in  the  following  order :  a  single  trunk  for  both  common  carotids  ;  then 
the  left  subclavian  ;  and,  lastly,  the  right  subclavian,  which  arose  from  behind  the  arch 
of  the  aorta,  and  passed  as  in  the  preceding  case.  A  fifth  variety  consists  in  a  combi- 
nation of  the  variety  by  transposition  either  with  the  variety  by  fusion  or  with  the  vari- 
ety by  multiplication. 

The  Common  Carotid  Arteries. 

Dissection. — Dissect  the  anterior  cervical  region,  preserving  all  the  parts  in  relation 
to  the  vessels.  In  order  to  see  the  tlioracic  portion  of  these  arteries,  remove  the  upper 
part  of  the  sternum. 

The  primitive  or  common  carotid  arteries  {ff,  jig.  198  ;  a, fig.  204)  are  the  arteries  of 
the  head.  Their  limit  above  is  marked  by  the  upper  border  of  the  thyroid  cartilage,  op- 
posite which  they  divide  into  the  external  and  internal  carotids. + 

They  are  two  in  number,  distinguished  as  the  right  and  left  :  they  differ  as  to  their 
origin,  their  length,  and  their  directions  ;  thus,  on  the  left  side,  the  common  carotid  ari- 
ses directly  from  the  aorta ;  on  the  right,  it  arises  from  a  trunk  common  to  it  and  to  the 
subclavian,  viz.,  the  innominate,  or  brachio-cephalic  artery  {e,fig.  198).  As  the  brachio- 
cephalic and  the  left  common  carotid  are  given  off  from  the  aorta  nearly  at  the  same 
level,  it  follows  that  the  left  common  carotid  is  longer  than  the  right  by  the  entire  length 
of  the  brachio-cephalic. 

It  follows,  also,  from  the  obliquity  of  the  arch  of  the  aorta,  that  the  left  common  ca- 
rotid is  placed  much  deeper  than  the  right  at  its  origin  ;  but,  in  the  cervical  region,  the 
two  carotids  are  upon  the  same  plane. 

They  pass  somewhat  obliquely  upward  and  outward  immediately  after  their  origin, 
but  they  are  directed  vertically  and  parallel  to  each  other  in  the  cervical  region. t  The 
interval  between  them  is  occupied  by  the  trachea  and  the  oesophagus  below,  and  by  the 
larynx  and  phaiynx  above.  Their  course  is  straight,  and  without  any  winding.  Their 
diameter  is  uniform  throughout,  a  circumstance  which  is  connected  with  the  absence 
of  any  collateral  branches.  The  caliber  of  these  arteries  is  relatively  larger  in  man  than 
in  other  animals ;  and  this  has  reference  to  the  greater  size  of  his  brain.  I  have  not  ob- 
served any  difference  in  diameter  between  the  right  and  left  common  carotids. 

As  about  one  inch  in  length  of  the  left  common  carotid  lies  in  the  thorax,  its  relations 
must  be  separately  studied  in  that  situation. 

Relatians  of  the  Thoracic  Portion. — In  front,  with  the  left  subclavian  vein,  and  the  ster- 
no-hyoid  and  sterno-thyroid  muscles,  which  separate  it  from  the  sternum  ;  behind,  with 
the  trachea  and  oesophagus,  and  with  the  left  subclavian  and  left  vertebral  arteries ;  on 
the  outside,  with  the  pleura  or  the  left  wall  of  the  mediastinum  ;  on  the  inside,  with  the 
brachio-cephalic  trunk,  from  which  it  is  separated  by  a  triangular  interval,  in  which  the 
trachea  is  visible. 

Relations  of  the  Cervical  Portion. — These  are  the  same  for  both  arteries.  In  front, 
each  common  carotid  is  covered  below  by  the  stemo-mastoid,  and  more  immediately  by 
the  sterno-hyoid,  sterno-thyroid,  and  omo-hyoid  muscles,  the  latter  of  which  crosses 
the  artery  obliquely.^  In  its  upper  half  it  corresponds  to  the  platysma  myoides,  which 
separates  it  from  the  skin.  The  cervical  fascia,  the  superior  thyroid  vein,  and  the  de- 
scendens  noni,  a  branch  of  the  hypoglossal  nerve,  are  in  more  immediate  relation  with 

*  Some  anomalies  of  the  arterial  system  of  man  may  be  in  some  measure  explained  from  the  normal  state 
of  the  arterial  system  of  certain  animals ;  but  the  number  of  such  cases  is  extremely  limited.  I  do  not  know 
whether  any  one  hai  ever  thought  of  applying-  to  these  anomahes  the  rule  of  the  arrest  of  development,  wliich 
some  have  lately  made  to  play  such  an  exaggerated  part  in  the  theory  of  the  vices  of  conformation. 

t  [The  common  carotid  has  been  seen  to  divide  above  the  os  hyoidos,  also  opposite  the  thyroid  cartilage, 
and  even  low  down  in  the  neck.] 

t  [In  consequence  of  the  larynx  being  wider  than  the  trachea,  the  common  carotids  arc  not  quite  parallel 
in  the  neck,  but  are  somewhat  farther  apart  above  than  below.] 

I)  In  order  to  omit  nothing,  I  should  say  that  the  common  carotid  is  crossed  obliquely  by  a  branch  which  i» 
given  off  from  the  superior  thyroid  artery  to  the  stemo-niastoid  muscle. 


THE  EXTERNAL  CAKOTID  ARTERY. 


515 


It.  The  most  important  of  these  relations  is  that  with  the  sterno-mastoid,  which,  in  a 
surgical  point  of  view,  may  be  regarded  as  its  satellite  muscle.  Behind,  the  common 
carotid  is  the  vertebral  column,  from  which  it  is  separated  by  the  pre- vertebral  muscles, 
the  great  sympathetic  nerve,  and  below  by  the  recurrent  nerve  and  inferior  thyroid 
artery.*  On  the  itiside,  it  is  in  relation  with  the  trachea,  oesophagus,  larynx,  and  thy- 
roid gland,  which  passes  in  front  of  the  artery  when  larger  than  usual ;  on  the  outside 
of  the  artery  is  the  internal  jugular  vein.  The  pneumogastric  nerve  lies  at  the  back, 
between  the  artery  and  vein.  The  common  carotids  are  also  surrounded  by  much  loose 
cellular  tissue,  and  by  some  lymphatic  glands. 

The  left  common  carotid  is  in  more  direct  relation  with  the  oesophagus  than  the  ar- 
tery of  the  right  side. 

The  common  carotids  give  off  no  branch  during  their  course  :  nevertheless,  it  is  not 
very  rare  for  this  artery  to  give  off  the  inferior  thyroid  artery,  or  a  supernumerary  branch 
known  as  the  middle  thyrmdA  Neabauer  has  seen  the  common  carotid  give  off  a  thy- 
roid artery,  and  the  internal  mammary  of  the  right  side. 

Terminal  Branches. — Having  reached  the  upper  border  of  the  thyroid  cartilage,  at  a 
variable  height,  according  to  the  subject,  the  common  carotid  divides  into  two  branches, 
called  the  external  and  internal  carotids,  which,  by  no  means  a  common  arrangement,  do 
not  leave  each  other  at  an  acute  angle,  but  remain  in  contact,  and  even  frequently  be- 
come crossed  before  they  separate.  The  point  of  division  is  also  remarkable  for  a  sort 
of  ampulla  or  dilatation,  which  the  primitive  carotid  exhibits.  Sometimes  the  primitive 
carotid  bifurcates  much  sooner  than  usually.  Morgagni  relates  a  case  in  which  the 
bifurcation  took  place  at  the  distance  of  an  inch  and  a  half  from  the  origin  of  the  ar- 
tery. Sometimes  the  primitive  carotid  does  not  terminate  in  a  bifurcation.  In  such  a 
case,  all  the  branches  given  off  by  the  external  carotid  arise  successively  from  the  prim- 
itive carotid,  which  penetrates  the  cranium  and  terminates  as  the  internal  carotid. 

The  External  Cakotid  Artery. 

Dissection. — Prolong  the  incision  made  for  exposing  the  conmion  carotid  as  far  as  th,e 
neck  of  the  condyle  of  the  lower  jaw.  Dissect  carefully  the  styloid  muscles  and  the  diga!s- 
tricus,  and  cautiously  separate  the  artery  from  the  surrounding  tissue  of  the  parotid  gland . 

The  external  or  superficial  carotid  artery  {h,fig.  204)  is,  in  a  great  measure,  intitw  ! 


Fig.  204. 


for  the  face,  and  has,  therefore,  been 
called  the  facial  carotid  by  Chaussier. 
It  arises  from  the  conunon  carotid, 
forming  one  of  its  two  divisions,  and 
extends  as  far  as  the  neck  of  the  con- 
dyle of  the  lower  jaw,  where  it  termi- 
nates by  dividing  into  the  temporal  and 
internal  maxillary  arteries. 

The  origin  of  this  artery  is  remark- 
able for  being  situated  on  the  inner 
side  of  the  internal  carotid.  It  as- 
cends vertically  as  high  as  the  digas- 
tricus,  and  passes  under  that  muscle ; 
it  is  then  directed  a  little  backward 
and  outward,  leaves  the  vertebral  col- 
umn, reaches  the  angle  of  the  lower 
jaw,  and  again  becomes  vertical  as  it 
proceeds  upward  to  the  neck  of  the 
condyle,  opposite  to  which  it  termi- 
nates. It  is  very  slightly  tortuous  in 
the  adult,  and  in  the  infant  is  almost 
straight.  In  the  adult  it  is  nearly  equal 
in  size  to  the  internal  carotid,  but  it  is 

much  smaller  in  young  subjects.  It  diminishes  rapidly  in  diameter,  on  account  of  thn 
number  of  branches  given  off  from  it,  so  that  at  its  termination  it  is  scarcely  one  tliird 
Its  origmal  size.  Sometimes  it  divides  immediately  into  a  sort  of  bunch  of  arterial  ves- 
sels ;in  other  cases  its  branches  arise  in  succession  from  the  common  carotid,  which  is 
then  directly  continuous  with  the  internal  carotid.  ± 

J\.^  l^^^^J  °^  relations  which  it  is  important  to  know  m  a  surgical  point  of  view  is  the  relation  which  often 
exists  behind,  between  the  right  primitive  carotid  and  the  trachea.  Where  this  anomaly  eiists,  the  brachio- 
cephalic trunk  arises  a  Lttle  more  to  the  left  side  than  usually  «:»J»t», 

t  This  supernumerai7  artery  arises  at  different  elevations,  'in  a  case  which  has  been  communicated  to  me 
.IJa    ^Tv't  i  '^^  '^'^'^^^  °l  s"P?"iumerary  thyroid  artery  was  given  off  by  the  right  primitive  ca- 

rotid at  the  distance  of  a  centrmeter  from  the  innominata.  It  passed  up  in  a  straight  line  into  the  gland,  where 
nfT.i?  i  ,1'  a"|=""'5t°'n°s'='i  freely  with  the  superior  and  inferior  thyroidian  arteries  on  each  side.  The  right 
inferior  thyjoidian  artery  was  not  half  as  voluminous  as  usual.  Mr.  Dubreuil,  who  teaches  anatomy  with  so 
much  talent  at  Montpelier,  has  communicated  to  me  several  arterial  anomalies,  which  are  to  be  inserted  in  a 
professional  work  that  he  is  prnparing  on  that  subject  in  a  surgical  point  of  view 

»  It  IS  doubtless  on  account  of  the  numerous  branches  given  off  by  the  external  carotid  that  several  ancient 


516  ANGEIOLOGY. 

Relations. — It  is  superficial  at  its  origin,  like  the  upper  part  of  the  common  carotid, 
and,  like  it,  is  merely  separated  from  the  skin  by  the  platysma  myoides ;  but  it  then 
dips  into  the  supra-hyoid  region,  below  the  digastricus,  the  stylo-hyoideus,  and  the  hypo- 
glossal nerve.*  Higher  up  it  is  situated  deeply  in  the  parotid  excavation,  surrounded 
on  all  sides  by  the  tissue  of  the  parotid  gland,  which,  on  this  account,  cannot  be  entire- 
ly extirpated  without  wounding  the  vessel. 

Collateral  Branches. — These  are  six  in  number,  and  are  arranged  into  three  sets,  viz., 
an  anterior  set,  consisting  of  the  superior  thyroid,  the  facial,  and  the  lingiud ;  a  posterior, 
including  the  occipital  and  the  auricular ;  and  an  internal  set,  formed  by  one  vessel,  the 
inferior,  or  ascending  pharyngeal. 

The  terminal  branches  are  two  in  number,  the  superficial  temporal  and  the  internal  max- 

The  Superior  Thyroid  Artery. 

The  superior  thyroid  artery  (d.  Jig.  204)  belongs  both  to  the  larynx  and  the  thyroid 
gland.  It  is  the  first  branch  given  off  from  the  external  carotid ;  it  rather  frequently 
arises  opposite  the  bifurcation  of  the  common  carotid,  which  in  this  case  would  seem  to 
divide  into  three  branches.  In  some  cases  it  arises  directly  from  the  common  carotid ; 
at  other  times  it  has  been  seen  to  come  off  by  a  conmion  trunk  with  the  lingual.  It  is 
always  of  considerable  size,  but  varies  in  this  respect,  maintaining  either  a  direct  rela- 
tion to  the  size  of  the  thyroid  body,  or  an  inverse  proportion  to  that  of  the  other  thyroid 
arteries. 

Direction. — It  is  at  first  airected  horizontally  forward  and  inward  ;  but  it  almost  im- 
mediately bends,  and  proceeds  vertically  to  the  upper  end  of  the  corresponding  lobe  of 
the  thyroid  gland,  in  which  it  terminates. 

Relations. — It  is  superficial  at  its  origin,  where  it  is  covered  only  by  the  skin  and  the 
platysma  ;  it  then  dips  under  the  omo-hyoid,  sterno-hyoid,  and  sterno-thyroid  muscles, 
and  it  is  also  covered  by  the  cervical  fascia  and  the  superior  thyroid  veins.  This  artery 
furnishes  several  collateral  branches,  viz.,  the  superier  laryngeal,  the  inferior  laryngeal  or 
crico-thyroid,  and  the  sterno-mastoid  branch,  t 

The  Superior  Laryngeal  Branch. — This  (c)  comes  off  from  the  thyroid,  at  the  point 
where  the  latter  changes  its  direction ;  sometimes  it  arises  from  the  external  carotid. 
In  certain  cases  it  is  so  large  that  it  may  be  regarded  as  formed  by  a  bifurcation  of  the 
thyroid.  In  one  case  where  it  was  wanting  on  the  left  side,  I  found  it  replaced  by  the 
right  superior  thjnroid,  which  was  almost  double  its  usual  size.  This  artery  passes 
transversely  inward  between  the  thyro-hyoid  muscle  and  the  membrane  of  the  same 
name,  which  it  perforates  along  with  the  superior  laryngeal  nerve  ;  having  reached  the 
cellular  tissue  behind  this  membrane,  it  divides  into  two  branches,  an  ascending,  or  epi- 
glottid  branch,  which  passes  upon  the  side,  then  in  front  of  the  epiglottis,  and  ramifies 
upon  it ;  and  a  descending,  or  laryngeal  branch,  properly  so  called,  which  passes  behind 
the  thyroid  cartilage,  between  it  and  the  thyro-arytenoid  muscle,  and  is  distributed  upon 
the  muscles  and  mucous  membrane  of  the  lar)Tix.  Not  unfrequently  the  superior  laryn- 
geal branch  enters  the  larynx  through  a  foramen  existing  in  the  thyroid  cartilage  in 
some  subjects. 

The  Inferior  Laryngeal  or  Crico-thyroid  Branch. — This  arises  from  the  internal  termina- 
ting branch  of  the  superior  thyroid  artery ;  it  is  more  remarkable  for  its  constant  presence 
than  for  its  size.  It  is  sometimes  wanting  on  one  side,  but  it  is  then  replaced  by  the 
superior  thyroid  artery  of  the  other  side.  It  passes  transversely  inward,  in  front  of  the 
crico-thyroid  membrane,  along  the  lower  border  of  the  thyroid  cartilage,  and  inosculates 
with  the  branch  of  the  opposite  side.  From  the  arch  thus  formed  twigs  proceed,  which 
perforate  the  crico-thyroid  membrane,  and  ramify  in  the  muscles  and  the  mucous  mem- 
brane of  the  larynx. 

It  is  not  uncommon  to  find  the  inferior  laryngeal  artery  dividing  into  two  branches  : 
one  superficial  and  transverse,  the  other  ascending,  which  passes  up  behind  the  thyroid 
cartilage. 

M.  Chassaignac  has  exhibited,  at  the  Anatomical  Society,  a  preparation,  in  which  the 
trunk  of  the  superior  thyroid  artery,  instead  of  giving  off  the  inferior  laryngeal  branch, 
passed  itself  transversely  over  the  crico-thyroid  ligament. 

I'.ie  Sterno-mastoid  Branch. — This  is  constant,  but  of  variable  size.  It  comes  off  from 
the  superior  thyroid,  a  little  below  the  superior  laryngeal,  and  passes  downward  to  reach 
the  deep  surface  of  the  sterno-mastoid  muscle,  to  which  it  is  distributed. 

Terminal  Branches. — Having  reached  the  gland,  the  thyroid  artery  divides  into  three 
branches,  viz.,  one  which  passes  between  the  gland  and  the  trachea ;  another,  which 

authors  have  not  described  this  vessel  as  a  particular  artery,  but  have  contented  themselves  with  describing 
the  branches  which  it  gives  off. 

*  [It  crosses  over  the  styloid  process,  the  stylo-glossus  and  pharjmgeus  muscles,  and  the  glosso-pharyngeal 
nerve,  which  lie  between  it  and  the  internal  carotid.] 

t  [The  first  branch  is  usually  a  small  one,  named  the  hyoid,  which  arises  opposite  the  great  comu  of  the 
OS  hyoides,  passes  inward  on  the  thyro-hyoid  membrane,  and  anastomoses  with  the  vessel  of  the  opposite 
side.} 


THE   FACIAL    AHTERY.  5X7 

proceeds  along  the  outer  border  of  the  corresponding  lobe  ;  and  a  third,  which  runs 
along  the  inner  border,  and  anastomoses  in  the  median  line  with  the  corresponding 
branch  of  the  opposite  side.  It  is  this  vessel  which  sometimes  gives  off  the  inferior 
laryngeal.* 

The  Facial,  the  Labial,  or  External  Maxillary  Artery. 

Dissection. — Let  the  head  fall  backward  by  means  of  a  billet  placed  under  the  neck, 
and  incline  it  towards  the  side  opposite  to  that  on  which  the  artery  is  to  be  laid  bare  ; 
dissect  carefully  the  digastricus  and  stylo-hyoid  muscles,  which  must  be  cut  superiorly 
at  their  origin  from  the  styloid  process  ;  dissect  the  sub-maxillary  gland,  then  the  mus- 
cles of  the  ia.ce,  avoid  injuring  the  numerous  branches  which  may  come  under  the  scalpel. 

The  facial  artery  (/,  figs.  204,  206),  so  called  from  its  distribution,  is  given  off  from 
the  front  of  the  external  carotid,  a  little  above  the  os  hyoides :  it  is  so  large  in  some 
subjects  that  it  seems  to  be  formed  by  a  bifurcation  of  the  extemcil  carotid.  It  pro- 
ceeds in  a  tortuous  course  from  below  upward,  and  then  from  behind  forward,  along 
a  groove  formed  in  the  sub-maxillary  gland.  After  leaving  this  groove,  it  passes  verti- 
cally upward,  crosses  the  body  of  the  lower  jaw  at  right  angles  in  front  of  the  masseter 
muscle,  becomes  oblique,  arrives  near  the  conunissure  of  the  lips,  reaches  the  furrow 
between  the  ala  nasi  and  the  cheek,  and  terminates  near  the  inner  angle  of  the  eye,  by 
anastomosing  with  one  of  the  branches  of  the  ophthalmic,  and  with  the  infra-orbital  ar- 
tery. The  termination  of  the  facial  artery  is  subject  to  numerous  individual  varieties. 
The  vessel  is  also  remarkable  for  being  extremely  tortuous,  a  condition  which  is  con- 
nected with  the  mobility  of  the  parts  supplied  by  this  artery,  which  runs  in  succession 
over  the  supra-hyoid,  the  inferior  maxillary,  the  buccal,  and  the  nasal  regions. 

Relations. — In  the  supra-hyoid  region  the  facial  artery  is  covered  by  the  digastric  and 
stylo-hyoid  muscles  ;  then,  along  the  base  of  the  jaw,  it  is  in  relation  with  the  outer  sur- 
face of  the  sub-maxillary  gland,  and  is  separated  from  the  skin  by  the  platysma  and  a 
great  number  of  lymphatic  glands.  In  the  facial  region,  the  artery  is  covered  below  by 
the  platysma,  higher  up  by  the  triangularis  oris  and  the  zygomaticus  major,  and  in  all  the 
rest  of  its  extent  by  a  greater  or  less  quantity  of  fat,  which  separates  it  from  the  skin ; 
it  lies  upon  the  inferior  maxilla,  against  which  it  may  be  compressed  in  front  of  the 
masseter,  also  upon  the  buccinator,  the  orbicularis  oris,  the  levator  communis,  and  the 
levator  proprius. 

Collateral  Branches. — The  following  branches  are  given  off  by  the  facial  artery  in  the 
supra-hyoid  region.  The  inferior  palatine,  a  small  branch  which  is  sometimes  derived 
from  the  external  carotid,  or  from  the  ascending  pharyngeal  artery,  passes  up  behind 
[or  between]  the  stylo-glossus  and  stylo-pharyngeus  muscles,  to  which  it  furnishes  some 
branches,  gains  the  side  of  the  pharynx,  and  is  distributed  to  the  tonsil,  which  it  covers 
with  its  ramifications,  and  also  to  the  velum  palati  and  the  pillars  of  the  fauces,  oppo 
site  which  it  anastomoses  with  several  branches  of  the  ascending  pharyngeal  artery.  1 
have  seen  the  palatine  branch  of  the  facial  extremely  large,  and  taking  the  place  of  the 
tonsillar  and  palatine  branches  of  the  ascending  pharyngeal  artery. 

The  sub-mental  branch  (g,fig.  204)  runs  along  the  inner  side  of  the  lower  border  of  the 
ramus  of  the  jaw,  between  the  digastricus  and  mylo-hyoideus,  passes  upward  in  front  of 
the  bone,  on  the  outer  side  of  the  anterior  attachment  of  the  digastricus,  and  ramifies  in 
the  skin  and  muscles  of  the  chin,  anastomosing  with  the  ramifications  of  the  inferior 
dental  artery.  Sometimes  the  sub-mental  divides  into  two  or  three  branches,  all  of  which 
terminate  in  the  same  manner,  after  perforating  the  digastric  muscle. 

Branches  for  the  Sub-maxillary  Gland. — These  are  three  or  four  in  number,  and  are 
large  in  proportion  to  the  organ  which  they  supply. 

The  Pterygoid  Branch. — This  is  a  small  branch  which  passes  into  the  internal  ptery- 
goid muscle. 

The  collateral  branches  of  the /aciaZ  region  are  divided  into  external  and  internal.  The 
external  branches  ramify  in  all  the  muscles  and  integuments  of  the  cheek,  and  anastomose 
freely  with  the  transverscdis  faciei,  a  branch  of  the  superficial  temporal :  the  most  re- 
markable of  these  branches  are  the  two  given  to  the  masseter  and  buccinator  muscles. 

Among  the  internal  branches,  besides  a  number  of  small  twigs  which  have  received  no 
names,  we  remark  the  following . 

The  inferior  coronary  or  labial  artery  (h),  which  is  given  off  from  the  facial,  a  little  be- 
low the  commissure  of  the  lips  ;  it  pursues  a  serpentine  course  in  the  substance  of  the 
lower  lip,  between  the  muscular  and  glandular  layers,  at  a  greater  or  less  distance  from 
the  free  border  of  the  lip,  and  anastomoses,  in  the  median  line,  with  the  corresponding 
vessel  of  the  opposite  side.  I  have  seen  this  artery  occupy  the  lower  or  adherent  border 
of  the  lower  lip  until  it  reached  the  median  line,  when  it  ascended  vertically  to  the  free 
border,  wh'ere  it  divided  into  two  equal  branches,  which  passed,  horizontally,  one  to  the 

*  I  have  seen  the  branch  winch  runs  along^  tlie  inner  border  of  the  thyroid  gland  pass  transversely  to  the 
left  side,  above  and  at  a  certain  distance  from  this  border ;  having  reached  the  median  line,  it  proceeded  ver- 
tically downward,  in  front  of  the  crico-thyroid  ligament,  to  the  middle  of  the  thyroid  gland,  where  it  gave  off 
the  right  and  left  inferior  laryngeal  branches.  The  left  thyroid  was  very  small,  and  only  furnished  the  ex- 
ternal branch  for  the  thyroid  gland. 


5f8 


ANGEIOLOGY. 


right  and  the  other  to  the  left,  in  order  to  form  a  second  coronary  artery,  smaller  than 
the  first. 

The  superior  coronary,  or  labial,  arises  opposite  the  commissure,  passes  in  the  upper 
lip  between  the  muscular  and  glandular  layers,  and  inosculates,  in  the  median  line,  with 
the  vessel  on  the  opposite  side.  Branches  are  given  off  from  this  arch  to  the  mucous 
membrane,  the  gums,  the  muscles,  and  the  skin.  One  branch  only  of  this  artery  requires 
a  special  description  ;  it  is  known  by  the  name  of  the  artery  of  the  septum  nasi  (z).  It 
comes  off,  in  the  median  line,  by  one,  two,  and  sometimes  three  branches,  which  pass 
vertically  upward,  and  then  horizontally  beneath  the  skin,  covering  the  under  surface  of 
the  septum  as  far  as  the  tip  of  the  nose,  where  they  anastomose  with  the  artery  of  the  ala. 

The  artery  of  the  ala  nasi,  or  lateral  artery  of  the  nose  (/),  which  is  very  often  the  ter- 
mination of  the  facial,  divides  into  two  branches  :  a  small  one,  that  runs  along  the  lower 
border  of  the  cartilage  of  the  ala,  and  anastomoses  with  the  anery  of  the  septum  ;  and  a 
larger  one,  that  runs  along  the  upper  convex  border  of  that  cartilage.  A  small  branch  pen- 
etrates into  the  interior  of  the  nares,  between  the  cartilage  and  the  opening  of  the  nostril. 

Termination  of  (he  Facial  Artery. — The  facial  artery  having  become  extremely  slender, 
sometimes  terminates,  under  the  name  of  the  angular  branch  (m),  upon  the  side  of  the 
nose,  by  anastomosing  with  the  nasal  branch  of  the  ophthalmic,  and  with  the  infra-orbit- 
al. At  other  times  its  termmation  is  formed  by  the  artery  of  the  ala  of  the  nose,  or  by 
the  superior  coronary  of  the  lip,  or  even  by  the  inferior  coronary.  I  have  seen  i'l  termi- 
nate in  the  artery  of  the  septum.  We  seldom  find  the  facial  arteries  of  both  sides  ahke. 
Sometimes  there  is  merely  a  trace  of  one,  while  the  other  is  very  much  developed,  and 
supplies  by  itself  alone  all  the  nasal  and  labial  branches.  No  artery  varies  more  thai? 
the  facial,  both  in  size  and  extent  of  distribution. 

Its  anastomoses  with  the  inferior  dental  and  infra-orbital  arteries,  branches  of  the  in 
ternal  maxillary,  as  well  as  those  with  the  ophthalmic,  a  branch  of  the  internal  carotid, 
should  be  particularly  noticed. 

The  Lingtial  Artery. 
Dissection. — Cut  the  hyoidian  insertions  of  the  mylo-hyoid  muscle,  which  is  to  be 
turned  up  from  below  upward ;  saw  the  inferior  maxillary  bone,  either  at  the  symphysis 
or  on  each  side  of  it.    Hook  the  tongue  and  draw  it  out  of  the  mouth,  and  maintain  it  in 
that  position  while  you  follow  the  artery  as  situated  at  its  inferior  surface. 

The  lingual  artery  {n,  figs.  204,  205),  which  is  very  large  considering  the  size  of  the 
Fig.  205.  organ  to  which  it  is  distributed,  comes  off  from  the  front  of  the  ex- 

ternal carotid,  between  the  facial  and  the  superior  thyroid,  and  often 
by  a  common  trunk  with  the  facial ;  it  passes  at  first  obliquely  up- 
ward, and  then  transversely  inward  and  forward,  along  the  upper 
margin  of  the  corresponding  great  cornu  of  the  os  hyoides :  oppo- 
site the  lesser  cornu  of  that  bone  it  changes  its  direction,  and  runs 
in  a  serpentine  course  from  behind  forward,  in  the  substance  of  the 
tongue  as  far  as  the  apex,  where  it  terminates  by  anastomosing 
with  the  artery  of  the  opposite  side  ;  in  the  latter  part  of  its  course 
it  is  named,  we  know  not  why,  the  ranine  artery  Q,  fig.  205  ;  rana, 
a  frog).  Its  remarkably  tortuous  course  is  connected  with  the  lia 
bility  of  the  tongue  to  undergo  great  changes  in  its  relative  dimen- 
sions. 

Relations. — It  is  deeply  seated,  at  its  origin,  under  the  digastric 
'*  and  stylo-hyoid  muscles  and  the  hypo-glossal  nerve ;  opposite  the 
OS  hyoides  (at  n.  fig.  205)  it  is  situated  between  the  hyo-glossus  (the  nerve  passing  over 
that  muscle)  and  the  middle  constrictor  of  the  pharynx  :  in  the  substance  of  the  tongue 
it  is  placed  between  the  genio-hyo-glossus  and  the  lingaalis,  and  is  accompanied  by  the 
lingual  branch  of  the  fifth  nerve  ;  consequently,  it  occupies  the  inferior  surface  Of  the 
tongue. 

Collateral  Branches. — A  small  transverse  branch,  the  hyoid  (e),  forms  an  anastomotic 
«irch  with  the  vessel  of  the  opposite  side,  upon  the  body  of  the  os  hyoides,  between  the 
genio-hyo-glossus  and  the  genio-hyoideus. 

The  dorsal  artery  of  the  tongue  (/),  generally  small  and  diflicult  to  demonstrate;  it 
arises  opposite  the  great  cornu  of  the  os  hyoides,  ascends  upon  the  lateral  border  of  the 
tongue,  near  the  anterior  pillar  of  the  fauces,  to  which  it  gives  branches,  then  passes 
forward  and  inward,  and  giving  several  epiglottid  branches,  which  anastomose  with 
those  of  the  opposite  side,  is  finally  distributed  to  the  caliciform  papillae.  In  the  whole 
of  its  course,  this  artery  lies  immediately  beneath  the  mucous  membrane. 

The  sub-lingual  artery  (i)  is  large  enough  to  be  regarded  by  some  as  resulting  from  the 
bifurcation  of  the  lingual,  which,  according  to  them,  takes  the  name  of  raninal  only  after 
it  has  furnished  the  sub-lingual  branch.  It  arises  as  often  from  the  facial,  by  a  common 
trunk  with  the  sub-mental,  as  from  the  lingual  itself  It  passes  horizontally  forward  be- 
tween the  mylo-hyoideus,  which  separates  it  from  the  sub-mental,  and  the  genio-hyo- 
glossus,  and,  in  company  with  the  Warthonian  duct,  runs  along  the  lower  border  of  the 


THE   OCCIPITAL  ABTERY,   ETC.  519 

•Qb-Iingual  gland,  to  which  it  furnishes  numerous  twigs,  and  then  divides  into  two 
branches  :  the  larger,  or  the  artery  of  the  franum,  anastomoses,  in  an  arch,  with  the  ves- 
sel of  tlie  opposite  side  above  thefraenum ;  while  the  smaller,  or  ascending  branch,  pass- 
es upon  the  sides  of  the  symphysis  menti,  and  sends  twigs  into  the  several  incisor  fora- 
mina, situated  behind  the  teeth  of  the  same  name.  It  is  this  artery  of  the  fraenum,  not 
the  ranine  artery,  which  is  liable  to  be  wounded  in  division  of  the  fraenum.  Not  unfre- 
quently  the  sub-lingual  artery  gives  off  a  superficial  branch,  which  passes  through  the  an- 
terior belly  of  the  digastricus,  and  ramifies  upon  the  region  of  the  chin,  like  the  analo- 
gous branches  of  the  sub-mental. 

Lastly,  in  the  substance  of  the  tongue,  the  lingual  artery  gives  off  superior,  internal,  and 
external  branches,  which  supply  the  muscles  and  the  papillary  membrane  oif  that  organ. 

The  Occipital  Artery. 

Dissection. — Detach  the  sterno-mastoideus  and  the  splenius  at  their  superior  inser- 
tions. To  uncover  more  completely  this  artery,  which  is  deeply  situated  between  the 
mastoid  process  and  the  transverse  process  of  the  atlas,  cut  with  a  chisel  or  saw  the 
mastoid  process  at  its  base,  turning  it  from  above  downward  with  the  muscles  which  are 
inserted  into  it ;  cut  the  styloid  process  at  its  base,  and  turn  the  styloid  muscles  down. 
Remove  carefully  the  skin  of  the  occipital  region,  so  as  to  enable  you  to  follow  the  sub- 
cutaneous branches. 

The  occipital  artery  (o  o,  fig.  204),  which  is  distributed  to  the  posterior  region  of  the 
head,  is  smaller  than  the  three  branches  of  the  external  carotid  already  described.  It 
arises  from  the  back  of  the  external  carotid,  on  a  level  with  the  lingual  or  the  facial, 
sometimes  immediately  below  the  parotid  gland  :  it  passes  obliquely  upward  and  back- 
ward, as  high  as  the  apex  of  the  mastoid  process  ;  it  then  passes  horizontally  backward, 
and  on  the  inner  side  of  the  splenius  muscle,  divides  into  two  ascending  branches  :  one 
external,  which  immediately  bends  upward  ;  the  other  internal,  which  is  continued  hori- 
zontally, and  is  then  reflected  vertically  upward  on  the  side  of  the  occipital  protuber- 
ance. These  two  branches,  which  are  very  tortuous,  cover  the  occipital  region  with 
their  numerous  ramifications,  and  reach  as  high  as  the  vertex,  anastomosing  with  each 
other,  and  with  the  superficial  temporal  arteries. 

It  is  situated  deeply  at  its  origin,  and  is  covered  by  the  digastric  muscle  and  the  hypo- 
glossal nerve  ;  it  is  still  more  deeply  situated  as  it  passes  between  the  mastoid  process 
and  the  atlas,  where  it  is  covered  by  the  digastric  and  the  sterno-mastoid  ;  its  horizon- 
tal portion  is  situated  between  the  obhquus  capitis  superior  and  the  splenius  muscle,  then 
between  the  complexus  and  the  splenius,  running  along  the  occipital  insertion  of  the  lat- 
ter muscle,  on  the  inner  side  of  which  it  becomes  sub-cutaneous.  The  two  branches 
into  which  this  artery  divides,  and  all  its  succeeding  ramifications,  are  situated  between 
the  skin  on  the  one  hand,  and  the  occipital  muscle  and  the  oceipito-frontal  aponeurosis 
on  the  other. 

Collateral  Branches. — Among  a  great  number  of  small  and  unnamed  ramusculi,  we 
shall  distinguish  the  following  branches  :  a  superior  sterno-mastoid  artery,  which  constant- 
ly exists,  but  is  sometimes  given  off  from  the  external  carotid  itself:  it  forms  a  curve, 
with  its  concavity  directed  downward,  under  which  the  hypo-glossal  nerve  turns  ;  it  then 
penetrates  the  deep  surface  of  the  upper  portion  of  the  stemo-raastoid  :  a  stylo-mastoid 
branch,  which  is  often  derived  from  the  posterior  auricular  artery :  a  meningeal  artery,  or 
posterior  mastoid,  which  enters  the  cranium,  either  by  the  foramen  mastoideum,  the  fo- 
ramen lacerum  posterius,  or  even  the  foramen  magnum,  and  is  distributed  to  the  dura 
mater  :  &  cervical  artery  {princeps  cervicis),  which  descends  between  the  splenius  and  com- 
plexus muscles,  and  may  be  followed  down  to  the  lower  part  of  the  neck ;  this  branch  is 
sometimes  of  considerable  size  ;  lastly,  very  often,  a  terminal  branch,  the  parietal,  which 
enters  the  cranium  by  the  parietal  foramen,  and  ramifies  in  that  portion  of  the  dura  ma- 
ter which  forms  the  superior  longitudinal  sinus. 

The  Posterior  Auricular  Artery^ 

Dissection. — ^Avoid  cutting  this  artery  at  its  origin  in  preparing  the  trunk  of  the  exter- 
nal carotid ;  turn  the  pinna  of  the  ear  forward  ;  seek  for  the  trurdc  of  the  artery  between 
the  meatus  auditorius  extemus  and  the  mastoid  process ;  follow  up  the  dissection  on 
one  side  towards  the  origin,  on  the  other  towards  the  termination  of  this  artery,  being 
guided  by  the  description. 

The  posterior  auricular  artery  {,s,fig.  204)  is  intended  for  the  pinna,  the  internal  ear,  and 
the  neighbouring  parts  of  the  cranium  :  it  is  usually  smaller  than  the  occipital,  but  is 
sometimes  as  large  ;  it  arises  from  the  back  of  the  external  carotid,  a  little  above  the 
occipital,'  and  rather  often  by  a  common  trunk  with  that  artery.  It  passes  vertically  up- 
ward, being  deeply  seated  under  the  digastricus  ;  it  is  then  covered  by  the  parotid  gland, 
which  it  perforates  to  gain  the  posterior  border  of  the  mastoid  process,  upon  which  it  di- 
vides into  two  branches,  a  mastoid,  and  an  auricular. 

In  this  course  it  gives  off  several  parotid  and  muscular  branches,  and  the  stylo-mastoid 
artery,  which  is  sometimes  derived  from  the  occipital.     The  stylo-mastoid  artery,  so  re- 


520  ANGEIOLOGY. 

markable  for  the  length  of  its  course,  dips  into  the  stylo-mastoid  foramen,  runs  the  whole 
length  of  the  aqueduct  of  Fallopius,  giving  off,  as  it  proceeds,  some  twigs  to  the  internal 
ear,  and  terminates  by  anastomosing  with  a  branch  of  the  middle  meningeal  artery,  which 
enters  by  the  aqueduct  of  Fallopius. 

The  terminal  mastoid  branch  of  the  posterior  auricular  passes  upward  and  backward  be- 
tween the  mastoid  process  and  the  skin,  and  subdivides  into  two  sub-cutaneous  ramus- 
culi :  one  horizontal,  which  passes  inward  along  the  occipital  attachment  of  the  sterno- 
mastoid  and  splenius ;  the  other  ascending,  which  continues  in  the  original  course  of 
the  vessel,  and  is  lost  in  the  skin  upon  the  outer  margin  of  the  occipitalis  muscle. 

The  terminal  auricular  branch  almost  always  divides  into  two  :  a  superior  and  an  infe- 
rior. The  superior  branch  runs  along  the  anterior  border  of  the  mastoid  process,  rami- 
■  fies  upon  the  upper  half  of  the  internal  surface  of  the  pinna,  and  turns  round  its  free  mar- 
gin, so  as  to  reach  the  external  surface.  The  inferior  branch  passes  behind  the  auditory 
meatus,  supplies  the  lobule  of  the  ear,  insinuates  itself  into  the  fissure  in  the  cartilage, 
between  the  helix  and  concha,  and  thus  gains  the  external  surface  of  the  pinna,  upon 
which  it  passes  upward  in  the  furrow  between  the  helix  and  antihelix.  It  terminates  by 
anastomosing  with  the  superior  branch. 

I  have  seen  the  auricular  artery  of  great  size,  to  supply  the  place  of  the  posterior 
branch  of  the  superficial  temporal. 

The  Parotid  Arteries. 
While  passmg  through  the  parotid  gland,  the  external  carotid  gives  ofl^  four  or  five 
large  branches  to  that  organ,  which  deserve  special  description.  They  arise  from  the 
carotid  at  right  angles,  cross  the  ramus  of  the  lower  jaw  also  at  right  angles,  and  divide 
into  a  great  number  of  ramifications,  most  of  which  are  lost  in  the  substance  of  the 
gland ;  the  remainder  are  distributed  to  the  skin  and  muscles.  One  or  more  of  these 
branches  pass  between  the  parotid  gland  and  the  masseter  muscle,  parallel  to  the  trans- 
versalis  faciei  artery,  and  reach  as  far  as  the  zygomaticus  major ;  others  gain  the  angle 
of  the  jaw,  and  are  lost  in  the  supra-hyoid  region. 

The  Inferior  or  Ascending  Pharyngeal,  or  Pharyngo-meningeal  Artery. 

Dissection. — Make  the  section  necessary  for  examining  the  pharynx,  as  described  in 
d  former  part  of  this  work  when  on  the  Anatomy  of  the  Pharynx.  The  steps  required 
for  this  purpose  render  it  advisable  that  the  study  of  this  artery  should  be  postponed  until 
after  that  of  the  internal  maxillary. 

The  ascending  pharyngeal  is  the  smallest  branch  of  the  external  carotid  :  it  arises  from 
the  inner  side  of  that  artery  opposite  the  lingual.  I  have  seen  it  arise  from  the  occipital. 
Not  unfrequently  it  is  given  off  either  from  the  angle  of  bifurcation  of  the  common  caro- 
tid, or  from  the  internal  carotid ;  and  in  this  last  case,  there  is  almost  always  a  very 
small  pharyngeal  branch  arising  from  the  external  carotid,  and  passing  transversely  in- 
ward to  the  pharynx. 

It  varies  in  size  to  a  certain  degree,  and,  as  it  appears  to  me,  in  an  inverse  ratio  to 
that  of  the  palatine  branch  of  the  facial.     I  have  seen  it  almost  as  large  as  the  occipital. 

Inunediately  after  its  commencement  the  ascending  pharyngeal  passes  vertically  up- 
ward, at  first  between  the  external  and  internal  carotid,  and  then  behind  the  internal  ca- 
rotid, with  which  latter  vessel  it  is  found  in  the  triangular  interval  between  the  pharynx 
and  the  internal  pterygoid  muscle  ;  it  then  almost  immediately  divides  into  two  branch 
es,  a  meningeal  and  a  pharyngeal. 

Before  dividing,  it  gives  off  an  inferior  pharyngeal  branch,  which  passes  transversely 
inward,  and  subdivides  into  ascending  and  descending  branches,  the  latter  of  which  an- 
astomose on  the  pharynx  with  some  twigs  of  the  superior  thyroid. 

The  meningeal  branch,  which  is  situated  behind  the  internal  carotid,  passes  vertically 
upward,  gives  off  twigs  to  the  superior  cervical  ganglion  of  the  sjTnpathetic  nerve,  to  the 
pneumogastric,  glosso-pharyngeal,  and  hypo-glossal  nerves,  and  to  the  accessory  nerve 
of  Willis,  enters  the  cranium  through  the  foramen  lacerum  posterius,  and  ramifies  upon 
that  portion  of  the  dura  mater  which  lines  the  inferior  occipital  fossa.  I  have  seen  this 
vessel  divide  into  a  great  number  of  branches,  one  of  which  entered  the  cranium  by  the 
carotid  canal,  and  another  by  the  foramen  lacerum  anterius. 

The  meningeal  branch,  and  sometimes  even  the  trunk  of  the  pharyngeal,  gives  off  a 
prcBvertebral  branch,  which  passes  upward  in  front  of  the  longus  colli  and  the  recti  antici 
major  et  minor,  supplying  these  muscles,  and  anastomosing  with  the  cervicalis  ascen- 
dens.  I  have  traced  a  branch  into  the  cranium  through  the  first  intervertebral  foramen 
(i.  e.,  along  the  superior  notch  of  the  atlas),  and  another  which  entered  the  vertebral  ca- 
nal between  the  atlas  and  axis.  I  regard  this  praevertebral  branch  as  supplementary  to  the 
cervicalis  ascendens  (a  branch  of  the  inferior  thyroid),  for  it  has  a  similar  distribution. 

The  pharyngeal  branch  passes  in  front  of  the  internal  carotid,  and  having  reached  the 
base  of  the  cranium,  divides  into  numerous  branches,  which  ramify  in  the  very  dense 
fibrous  tissue  found  at  the  occipital  attachment  of  the  pharynx  :  they  are  all  reflected 
downward,  and  are  distributed  upon  the  Eustachian  tube  and  the  muscles  of  the  pharynx. 


THE    TEMPORAL  ARTERY.  S^f 

In  a  case  in  which  the  palatine  branch  of  the  facial  artery  was  absent,  this  pharyngea. 
branch  was  very  large  and  supplied  the  tonsil,  and,  finally,  ramified  in  the  velum  palati. 

The  Temporal  Artery. 

Dissectton. — ^Tum  bacK  the  parotid  gland  ;  seek  for  the  artery  under  the  skin  of  the 
temporal  region  ;  follow  its  different  collateral  and  terminal  branches  upon  the  cranium 
as  far  as  the  vertex,  on  the  face,  and  on  the  ear. 

The  temporal  or  superficial  temporal  artery  (p,  fig.  204)  appears,  by  its  direction,  to  form 
the  continuation  of  the  external  carotid.  It  commences  opposite  the  neck  of  the  con- 
dyle of  the  lower  jaw,  between  it  and  the  external  auditory  meatus,  which  is  behind  ;  it 
passes  vertically  upward,  immediately  behind  the  zygomatic  arch,  reaches  the  temporal 
region,  where  it  describes  some  curves,  still  continuing  its  vertical  course,  and  termi 
nates  by  bifurcating  at  the  middle,  or  sometimes  the  upper  part  of  that  region. 

Relations. — It  is  covered  at  its  origin  by  the  parotid  gland ;  it  becomes  subcutaneous 
as  soon  as  it  passes  beyond  the  zygomatic  arch,  and  then  rests  upon  the  temporal  fziscia 
at  first,  and  upon  the  epicranial  aponeurosis  afterward.  Its  superficisd  position,  added 
to  its  proximity  to  a  bony  surface,  render  it  easily  compressible,  and  explain  why  this 
artery,  and  especially  its  anterior  or  frontal  branch,  is  generally  chosen  for  arteriotomy. 

Collateral  Branches. — These  are  divided  into  anterior,  posterior,  and  interned. 

The  Anterior  Branches. — The  most  remarkable  of  these  is  the  transversalis  faciei  (u), 
which  arises  from  the  temporal  immediately  after  its  origin,  opposite  the  neck  of  the 
condyle  of  the  lower  jaw.  and,  consequently,  in  the  substance  of  the  parotid  gland  :  it 
very  often  comes  directly  from  the  external  carotid.  It  varies  much  in  its  size,  which 
is  generally  in  an  inverse  proportion  to  that  of  the  facial  artery.  It  proceeds  horizon 
tally  forward,  across  the  direction  of  the  neck  of  the  condyle  and  the  masseter  muscle, 
about  six  lines  below  the  zygoma,  above  the  Stenonian  duct,  which  runs  parallel  to  it. 
Tlie  transversalis  faciei  gives  an  articular  branch  to  the  temporo-maxillary  articulation, 
and  several  deep  masseteric  branches,  of  which  one  of  considerable  size  penetrates  the 
back  part  of  the  muscle,  and  anastomoses  with  the  masseteric  branch  of  the  internal 
maxillary.  It  also  gives  a  small  twig,  which  runs  along  the  Stenonian  duct.  At  the 
anterior  margin  of  the  masseter  the  transverse  facial  artery  subdivides  into  a  great  num- 
ber of  cutaneous,  muscular,  and  anastomotic  branches.  Among  the  first  we  should  notice 
a  maiar  cutaneous  branch  ;  and  among  the  muscular  branches,  those  which  are  distributed 
to  the  great  zygomatic  muscle.  The  muscular  branches  of  the  transversalis  faciei  may 
be  traced  in  one  direction  as  far  as  the  orbicularis  palpebrarum,  and  in  another  into  the 
levator  proprms  fibii  superioris.  The  anastomotic  branches  establish  an  intimate  com- 
munication between  the  temporal  artery  and  the  buccal,  infra-orbital,  and  facial  arteries. 

A  second  anterior  branch  of  the  temporal  artery  also  requires  special  notice,  viz.,  the 
orbital,  which  is  given  off  above  the  zygomatic  arch,  passes  from  behind  forward,  be- 
tween the  superficial  and  deep  layers  of  the  temporal  fascia,  then  behind  the  orbicularis 
muscle,  which  it  supplies,  as  well  as  the  corresponding  skin,  and  anastomoses  with  the 
superior  palpebral  branch  of  the  ophthalmic.  This  artery  is  very  variable  in  regard  to 
size.  I  have  seen  it  very  large  and  reflected  upward,  between  the  frontalis  muscle  and 
the  skin,  parallel  to  the  supra-orbital  branch  of  the  ophthalmic,  and  capable  of  being  fol- 
lowed as  far  as  the  parietal  region.  From  the  bend  which  it  forms  by  turning  upward, 
it  gives  off  a  palpebral  branch,  which  completes  the  superior  palpebral  arch,  and  also  a 
branch  which  anastomoses  with  the  supra-orbital.  This  orbital  branch  of  the  tempered 
does  not  exist  in  all  subjects  ;  the  branches  which  it  furnishes  are  then  given  off  direct- 
ly from  the  temporal. 

The  posterior  branches  consist  of  the  anterior  auriculars  (v),  which  are  irregular  as  to 
number  :  the  lower  branches  are  distributed  to  the  lobule,  the  middle  ones  to  the  exter- 
nal auditory  meatus,  and  the  upper  branches  to  the  highest  part  of  the  pinna. 

The  internal  branch  is  the  middle  deep  or  sub-aponeurotic  temporal  artery ;  it  arises  from 
the  temporal  above,  sometimes  on  a  level  with  the  zygoma,  perforates  the  fascia,  and  is 
distributed  to  the  temporal  muscle,  anastomosing  with  the  anterior  and  posterior  deep 
temporal  branches  derived  from  the  internal  maxillary. 

Terminal  Branches. — Of  the  two  branches  into  which  the  temporal  artery  divides,  the 
anterior  or  frontal  {q)  passes  forward  and  upward  towards  the  frontal  region,  upon  which 
it  ramifies,  anastomosing  with  the  branches  of  the  frontal  and  supra-orbital  arteries,  and 
with  the  temporal  of  the  opposite  side.  This  branch  is  divided  in  the  operation  of  arte- 
riotomy. The  posterior  or  parietal  branch  (y)  is  larger  than  the  anterior :  it  passes  up- 
ward and  ramifies  upon  the  parietal  bone,  anastomosing  with  the  auricular  and  occipital 
arteries,  with  the  frontal  branch  of  the  temporal,  and  with  the  temporal  of  the  opposite 
side.     It  is 'sometimes  derived  from  the  auricular  artery. 

The  Internal  Maxillary  Artery. 
Dissection. — Saw  through  the  zygomatic  arch  in  two  places,  and  turn  it  downward  to- 
gether with  the  masseter  muscle,  taking  care  not  to  tear  the  masseteric  artery. 
Dissect  the  temporal  muscle,  and  saw  through  the  coronoid  process  of  the  inferior 

Uuu 


SS2  ANGEIOLOGY. 

maxilla.  Saw  through  the  cranium  circularly,  and  remoTc  the  brain,  which  may  be  put 
into  diluted  nitric  acid  or  alcohol,  to  be  hardened  for  the  subsequent  dissection  of  the 
cerebral  arteries.  The  artery  may  then  be  exposed  in  two  ways,  either  from  the  outer 
or  else  from  the  upper  wall  of  the  zygomatic  fossa. 

It  may  be  reached  from  the  outer  wall  of  the  zygomatic  fossa  by  sawing  through  the 
lower  jaw  in  front  of  the  masseter,  by  disarticulating  the  condyle,  or,  rather,  by  sawing 
it  across  its  neck,  and  by  carefully  dissecting  the  pterygoid  muscles 

The  artery  can  be  reached  from  the  upper  wall  by  making  two  sections  in  this  part  of 

the  bone,  which  will  meet  at  an  acute  angle  in  the  foramen  spinosum  of  the  sphenoid  bone. 

The  branches  of  this  artery,  especially  those  which  are  e"hclosed  in  bony  canals,  such 

as  the  dental,  the  pterygo-palatine.  the  vidian,  dec,  must  be  dissected  by  carving  out 

their  courses  in  the  bone. 

A  vertical  section,  made  from  oefore  backward  through  the  middle  of  the  face,  facili- 
tates the  examination  of  this  artery,  and  enables  us  to  see  the  terminations  of  its  nasal, 
palatine,  and  pharyngeal  branches. 

The  internal  maxillary  artery  (e,  fig.  206),  little  known  to  the  older  anatomists,  but  ac- 
Fig.  206.  curately  described  by  Haller,  is  the  continuation  of  the 

external  carotid,  at  least  as  far  as  size  is  concerned. 
Immediately  after  its  origin,  it  forms  a  curve,  and 
passes  deeply  to  the  inner  side  of  the  neck  of  the  con- 
dyle of  the  lower  jaw. 

Tortuous  and  horizontal  in  the  first  part  of  its  course, 
it  traverses  the  zygomato-maxillary  fossa  diagonally, 
passes  forward,  inward,  and  a  little  upward,  to  reach 
the  highest  part  of  the  tuberosity  of  the  superior  max- 
illary bone,  upon  which  tuberosity  it  describes  a  very 
considerable  curve  with  the  convexity  turned  for- 
ward, and  then  dips  into  the  bottom  of  the  zygomat- 
ic fossa,  i.  e.,  the  spheno-maxillary  fossa,  where  it  ter- 
minates by  one  or  several  branches,  called  the  sphe- 
no-palatine.  The  tortuous  course  of  the  internal  max- 
illary is  connected  with  the  great  number  of  branches 
given  off  from  it. 

Relations. — Opposite  the  neck  of  the  condyle,  it  is  situated  between  the  condyle,  to 
which  it  is  applied,  and  the  styloid  process — an  important  relation  in  a  surgical  point  of 
view.  Its  relations  in  the  zygomato-maxillary  fossa  are  not  very  definite.  Some  anat- 
omists, with  Bichat  and  Meckel,  state  that  it  is  situated  between  the  internal  and  exter- 
nal pterygoid  muscles  ;  others,  with  Haller,  that  it  is  placed  in  front  of  the  external  pte- 
rygoid, i.  e.,  between  that  muscle  and  the  temporal.  Both  modes  of  distribution  are 
equally  common,  and  I  have  even  seen  one  existing  on  the  right,  and  the  other  on  the 
left  side  in  the  same  subject.  If  the  internal  maxillary  is  situated  betwt  en  the  ptery- 
goids, it  passes  directly  forward,  on  the  outside  of  the  dental  and  lingual  nerves  ;  when 
it  has  to  get  between  the  external  pterygoid  and  the  temporal,  it  bends  downward  and 
then  upward,  so  as  to  embrace  the  lower  half  of  the  circumference  of  the  external  pte- 
rygoid :  in  this  manner  it  gains  the  outer  surface  of  that  muscle,  appears  opposite  the 
sigmoid  notch  of  the  lower  jaw,  and  passes  from  behind  forward,  between  the  external 
pterygoid  and  temporal  muscles ;  in  both  cases  it  passes  between  the  two  origins  of  the 
external  pterygoid,  in  order  to  reach  the  pterygo-maxillary  fissure. 

Collateral  Branches. — These  are  thirteen  in  number,  and  are  divided  into  those  arising 
on  the  inner  side,  and  near  the  neck  of  the  condyle,  viz.,  the  tympanic,  the  middle  menin- 
geal, and  inferior  dental,  the  posterior  deep  temporal,  the  masseteric,  the  pterygoids,  and  the 
small  meningeal  arteries  ;  those  arising  near  the  maxillary  tuberosity,  viz.,  the  buccal,  the 
anterior  deep  temporal,  the  alveolar,  and  the  infra-orhital  arteries ;  and  those  arising  with- 
in the  spheno-maxillary  fossa,  viz.,  the  vidian  ot  pterygoid,  the  pterygo-palatine,  and  the 
guperior  palatine  arteries. 

Branches  arising  near  the  Neck  of  the  Condyle. 

The  tympanic  artery  is  a  very  small  branch,  which  sometimes  arises  from  the  tempo- 
ral, and  sometimes  from  the  inferior  dental ;  it  is  distributed  to  the  external  auditory 
meatus  and  the  temporo-maxillary  articulation,  and  penetrates  through  the  Glasserian 
fissure  into  the  cavity  of  the  tympanum,  to  the  muscles  and  walls  of  which  it  sends  its 
ramifications. 

The  middle  or  great  meningeal  artery,  or  spheno-spinous  artery,  is  destined  for  the  dura 
mater  and  the  bones  of  the  cranium ;  it  almost  always  arises  from  the  internal  maxilla- 
ry before  the  dental,  but  sometimes  in  the  same  situation  ;  it  passes  vertically  upward, 
behind  the  neck  of  the  condyle,  and  gains  the  foramen  spinosum  in  the  sphenoid  bone, 
through  which  it  enters  into  the  interior  of  the  cranium ;  it  is  then  reflected  upon  the 
anterior  margin  of  this  foramen,  becomes  horizontal,  and  divides  into  two  branches,  an 
interior  and  a  posterior.     The  anterior  branch  is  the  larger ;  it  runs  upon  the  outer  ex- 


THE    INTERNAL   MAXILLARY    ARTERY.  "iSfe 

tremity  of  the  lesser  wing  of  the  sphenoid,  and  reaches  the  anterior  angle  of  tho  parietal 
bone,  where  it  is  received  into  an  imperfect,  and  sometimes  even  into  a  complete  bony 
canal,  and  then  divides  and  subdivides  in  the  ramified  grooves  upon  the  internal  surface 
of  the  parietal  bone.  Its  branches  may  be  traced  even  into  the  walls  of  the  longitudinal 
sinus. 

The  posterior  branch  is  smaller,  and  passes  backward  and  upward  upon  the  squamous 
portion  of  the  temporal  bone,  and  upon  the  internal  surface  of  the  parietal  bone,  enters 
into  the  ramified  grooves  upon  that  surface,  and  terminates  in  the  dura  mater  and  the 
bones  of  the  cranium.  The  ultimate  twigs  of  the  middle  meningeal  artery  anastomose 
with  those  of  the  opposite  side,  and  with  the  branches  of  the  anterior  and  posterior  me- 
ningeal arteries. 

Relations. — In  the  first  part  of  its  course,  it  is  very  deeply  situated,  and  is  in  relation 
in  front  with  the  condyloid  attachments  of  the  external  pterygoid  muscle  ;  in  the  crani- 
um it  is  situated  on  the  outer  surface  of  the  dura  mater,  between  that  membrane  and  the 
bones,  into  the  substance  of  which  it  sends  a  number  of  extremely  fine  ramusculi.  The 
relation  of  the  two  divisions  of  this  artery  with  the  two  inferior  angles  of  the  parietal 
bone  deserves  notice  in  a  surgical  point  of  view.  In  consequence  of  its  sending  branch- 
es into  the  bones,  separation  of  the  dura  mater  is  always  followed  by  effusion  of  blood. 

The  middle  meningeal  artery  also  gives  off  some  collateral  branches.  On  the  outside 
of  the  cranium  it  furnishes  some  unnamed  twigs.  Within  the  cranium  it  gives  a  small 
branch,  named  the  vidian,  which  enters  the  aqueduct  of  Fallopius  through  the  hiatus  Fal- 
lopii,  and  supplies  the  facial  nerve,  ramifying  in  its  neurilemma,  and  anastomosing  with 
the  stylo-mastoid  branch  of  the  occipital  artery  ;  some  small  branches,  which  supply  the 
fifth  or  trigeminal  nerve,  and  evidently  anastomose  with  the  meningeal  branches  of  the 
internal  carotid ;  a  small  twig,  which  enters  the  canal  for  the  internal  muscle  of  the 
malleus,  and  is  distributed  upon  that  muscle ;  opposite  the  sphenoidal  fissure,  several 
orbital  branches,  which  enter  the  orbit  at  the  narrowest  part  of  that  fissure,  or  even  by 
proper  canals  in  its  neighbourhood ;  and,  lastly,  some  rather  large  temporal  branches, 
which  pass  into  the  great  alae  of  the  sphenoid  at  their  orbital  surface,  and  anastomose  in 
the  temporal  fossa  with  the  deep  temporal  arteries  :  not  unfrequently  the  lachrymal  ar- 
tery, or  a  small  supplementary  lachrymal  artery,  is  furnished  by  the  middle  meningeal. 

The  inferior  dental  artery  (d)  is  the  artery  of  the  lower  jaw :  it  generally  arises  on  a 
level  with  the  middle  meningeal,  but  sometimes  before  and  sometimes  after  that  vessel ; 
it  passes  downward,  along  the  inner  surface  of  the  ramus  of  the  jaw,  between  the  bone 
and  the  internal  pterygoid,  sending  off  branches  to  that  muscle,  but  being  separated 
from  it  by  the  fibrous  band  called  the  spheno-maxillary  ligament ;  it  thus  reaches  the 
superior  orifice  of  the  dental  canal,  before  entering  which  it  gives  off  a  small  branch 
that  passes  downward  and  forward  in  a  groove  on  the  inner  surface  of  the  jaw,  and  ter- 
minates in  the  mylo-hyoid  muscle. 

The  inferior  dental  artery  traverses  the  entire  length  of  the  dental  canal,  accompanied 
by  the  nerve  of  the  same  name.  Opposite  the  bicuspid  teeth  it  divides  into  two  branch- 
es :  a  menial  branch,  the  larger,  which  escapes  through  the  mental  foramen,  and  anasto- 
moses with  the  submental  artery  and  the  inferior  coronary  artery  of  the  lip ;  and  an  in- 
cisor branch,  which  continues  in  the  original  course  of  the  artery,  passes  beneath  the 
canine  and  incisor  teeth,  and  is  lost  in  the  diploe  opposite  the  symphysis. 

During  its  course,  the  dental  artery,  as  well  as  its  incisor  branch,  gives  off  a  great 
number  of  twigs,  which  are  lost  in  the  diploe  of  the  bone  ;  and  a  series  of  dental  branches, 
which  correspond  in  number  with  the  roots  of  the  teeth,  penetrate  into  the  alveoli,  and 
from  thence  into  the  teeth  through  the  foramen  observed  at  the  apex  of  each  fang. 

The  posterior  deep  temporal  artery  (g)  arises  opposite  the  sigmoid  notch,  passes  verti- 
cally upward  between  the  external  pterygoid  and  the  temporal  muscles,  gains  the  pos- 
terior border  of  the  latter  muscle,  gets  between  that  border  and  the  temporal  fossa,  re- 
mains in  contact  with  the  periosteum,  and  then  divides  and  subdivides  so  as  to  termi- 
nate partly  in  the  temporal  muscle  and  partly  upon  the  periosteum,  anastomosing  with 
the  middle  and  anterior  deep  temporal  arteries.  It  often  gives  off  the  masseteric,  and 
sometimes  the  buccal  artery. 

The  masseteric  artery  is  a  small  branch,  the  size  of  which  is  inversely  proportioned  to 
that  of  the  masseteric  branch  of  the  transversalis  faciei.  It  often  arises  by  a  common 
trunk  with  the  posterior  deep  temporal,  passes  outward  in  front  of  the  condyle,  and,  tliere- 
fore,  in  the  notch  between  the  condyle  and  the  coronoid  process,  and  enters  the  internal 
surface  of  the  masseter,  in  which  muscle  it  anastomoses  with  the  masseteric  branches 
given  off  by  the  transversalis  faciei  and  facial  arteries. 

The  pterygoid  arteries  are  irregular  in  number ;  some  of  them  arise  directly  from  the 
internal  maxillary,  others  from  the  posterior  deep  temporal  and  the  middle  meningeal. 

The  small  meningeal  artery  is  not  constant,  but  I  have  seen  it  in  one  case  as  large  as  ■ 
the  middle  meningeal ;  it  arises  at  the  same  height  as  the  inferior  dental,  passes  between 
the  pterygoid  muscles,  and  divides  into  two  branches,  one  of  which  turns  round  the  ori- 
gin of  the  internal  pterygoid,  and  terminates  in  the  velum  palati  and  the  nasal  fossae  ; 
and  another,  which  passes  vertically  upward,  between  the  external  pterygoid  and  the 


m 


ANGEIOLOGY. 


upper  wall  of  the  zygomatic  fossa,  enters  the  cranium  by  the  foramen  ovale,  and  sup- 
plies the  trip^eminal  nerve  and  the  dura  mater,  anastomosing  with  small  branches  given 
off  from  the  internal  carotifl. 

Branches  arising  near  the  Tuberosity  of  the  Superior  Maxillary  Bone. 

The  buccal  artery  (h)  is  a  small  branch  of  variable  size,  and  sometimes  exists  only  in 
a  rudimentary  state.  It  rather  frequently  arises  by  a  common  trunk  with  the  superior 
dental  artery,  passes  in  a  tortuous  course  from  behind  forward,  between  the  ramus  of 
the  lower  jaw  and  the  internal  pterygoid  muscle,  emerges  in  front  of  the  ramus,  and  is 
lost  in  the  buccinator  muscle,  anastomosing  with  the  buccal  branches  of  the  facial  and 
transversalis  faciei. 

The  anterior  deep  temporal  artery  (i)  is  of  considerable  size  :  it  passes  vertically  up- 
ward, along  the  anterior  border  of  the  temporal  muscle,  with  which  it  is  in  contact,  is 
lost  in  that  muscle,  anastomosing  with  the  posterior  deep  temporal  and  the  middle  tem- 
poral. It  gives  off  some  extremely  delicate  orbital  branches,  which  traverse  the  canals 
in  the  malar  bone,  and  are  lost  in  the  adipose  tissue  of  the  orbit. 

The  alveolar  or  superior  dental  (Z)  often  arises  by  a  common  trunk  with  the  infra-or- 
bital, passes  in  a  very  tortuous  manner  forward  and  downward  upon  the  tuberosity  of 
the  superior  maxilla,  and  divides  into  several  branches  ;  some  of  these,  having  reached 
the  alveolar  border,  are  reflected  upon  the  margins  of  the  alveoli,  pass  into  their  cavities, 
and  ramify  in  the  alveolo-dental  periosteum  ;  other  branches  enter  the  small  posterior 
dental  canals,  penetrate  into  the  alveoli  of  the  molars  and  bicuspids,  and  divide  into  as 
many  ramusculi  as  there  are  roots  to  each  of  those  teeth.  Several  of  these  branches 
penetrate  into  the  maxillary  sinus.  I  have  seen  one  which  ran  along  this  sinus  from 
behind  forward  near  its  lower  wall,  was  reflected  upward  on  the  anterior  wall  of  the 
same  cavity,  and  entered  the  base  of  the  ascending  process  of  the  superior  maxilla,  at 
which  point  I  could  no  longer  follow  it.  This  branch  was  situated  between  the  lining 
membrane  of  the  sinus  and  the  bones.  All  the  divisions  of  the  alveolar  artery  furnish 
branches  to  the  superior  maxillary  bone,  and,  at  the  same  time,  supply  them  to  the  cor- 
responding teeth.  Lastly,  some  very  delicate  twigs  of  the  superior  dental  artery  enter 
the  buccinator  muscle. 

The  infra-orbital  artery  arises  from  the  internal  maxillary  opposite  the  spheno-mEixil- 
lary  fissure,  sometimes  alone,  sometimes  by  a  common  trunk  with  the  superior  dental, 
immediately  enters  and  then  traverses  the  infra-orbital  canal,  emerges  at  the  infra-or- 
bital foramen,  and  divides  into  a  great  number  of  branches  (m),  which  are  distributed  to 
the  skin  and  mucous  membrane  of  the  cheek,  anastomosing  with  the  facial  artery,  the 
transversalis  faciei,  and  the  alveolar  and  buccal  branches  just  described.  Several  branch- 
es enter  the  alveoli  of  the  canine  and  incisor  teeth  at  their  borders  :  others  penetrate 
into  the  nasal  fossae  at  the  nostril. 

During  its  course,  the  infra-orbital  artery  furnishes  a  very  remarkable  branch,  which 
enters  the  cavity  of  the  orbits,  where  it  divides  into  two  branches,  one  of  which  passes 
directly  forward,  and  is  lost  in  the  lower  eyelid,  while  the  other,  which  is  larger,  turns 
inward,  and  inosculates  with  the  inferior  palpebral  branch  of  the  ophthalmic  artery ;  an- 
other branch  of  the  infra-orbital  artery  enters  the  anterior  dental  canal,  to  supply  the 
canine  and  incisor  teeth,  penetrating  into  the  foramina  at  the  points  of  their  fangs,  in 
the  same  way  as  in  the  other  teeth. 

Branches  arising  in  the  Pterygo-maxillary  Fossa. 

The  vidian  or  pterygoid  artery  is  a  very  small  vessel,  which,  immediately  after  its  com- 
mencement, enters  the  vidian  canal,  traverses  its  whole  length,  and  then  ramifies  in  the 
pharynx  and  around  the  Eustachian  tube. 

I'he  pterygo-palatine  artery  is  as  small  as  the  preceding,  below  and  to  the  inner  side 
of  which  it  is  situated  :  it  traverses  the  pterygo-palatine  canal,  and  terminates  in  the 
pharynx  and  on  the  Eustachian  tube.  It  sometimes  arises  from  the  spheno-palatine  artery. 

The  superior  palatine  artery  is  larger  than  the  preceding  branches,  and  pursues  a  down- 
ward course  :  it  arises  opposite  the  pterygo-maxillary  fissure,  passes  vertically  down- 
ward, enters  the  posterior  palatine  canal,  and,  having  emerged  from  its  inferior  orifice, 
is  reflected  from  behind  forward,  advances  in  a  tortuous  manner  (r,  fig.  205)  between 
the  hard  palate  and  the  mucous  membrane,  in  the  groove  which  runs  along  the  alveolar 
border,  and  forms  an  anastomotic  arch  in  the  median  line,  with  the  palatine  artery  of 
the  opposite  side.  Before  entering  the  posterior  palatine  canal,  it  gives  off  some  branch- 
es, which  run  through  the  accessory  palatine  canals,  and  ramify  upon  the  velum  palati. 
While  upon  the  hard  palate,  it  sends  off  branches,  which  are  distributed  to  the  glands 
of  the  mucous  membrane  ;  others,  which  are  distributed  to  the  gums,  and  enter  at  the 
margins  of  the  alveoli,  and  supply  the  alveolo-dental  periosteum ;  and,  lastly,  a  small 
nasal  branch  {t,  fig.  205),  which  enters  the  anterior  palatine  canal,  bifurcates  above  like 
that  canal  itself,  so  as  to  penetrate  into  each  of  the  nasal  fossae,  and  anastomoses  with 
the  spheno-palatine  artery  of  both  sides.* 

*  There  are,  in  the  interior  of  the  bones  of  the  face,  as  in  all  spongy  bones,  true  arterial  canals,  the  study  of 
which  is  not  less  important  than  that  of  the  venous  canals  found  in  similar  situations. 


THE  INTERNAL  CAROTID.  525 

Terminal  Branch  of  the  Internal  Maxillary  Artery. 

This  is  named  the  spheno-palatine ;  it  is  a  large  vessel,  often  multiple,  and  is  intended 
exclusively  for  the  pituitary  membrane  ;  it  passes  from  below  upward,  in  a  tortuous  man- 
ner, to  penetrate  the  corresponding  nasal  fossa,  by  the  spheno-palatine  foramen,  that  is, 
at  the  back  part  of  the  superior  meatus,  where  it  immediately  divides  into  two  branches  : 
one  internal  {s,  fig.  205),  which  passes  obliquely  downward  and  forward,  covers  the  sep- 
tum with  a  complicated  network,  and  anastomoses  in  front  with  the  nasal  branch  of  the 
superior  palatine  ;  the  other  external,  which  divides  into  three  ramusculi  for  the  three 
meatuses,  and  ramifies  in  them  and  upon  the  turbinated  bones.  Some  of  the  twigs  en- 
ter the  sphenoidal  and  maxillary  sinuses,  the  posterior  and  the  anterior  ethmoidal  cella^ 
the  frontal  sinus,  and  the  lachrymal  canal 

All  these  arteries  form  areolae  of  different  sizes  in  the  pituitary  membrane,  and  give  t, 
in  successful  injections,  a  reticulated  aspect ;  they  are  situated  between  the  periosteum 
and  the  pituitary  membrane,  properly  so  called.  The  arteries  of  the  turbinated  bones 
are  lodged  in  the  areolar  cells  on  the  surface  of  those  bones,  and  in  the  arterial  canals 
which  are  hollowed  out  of  them 

Summary  of  the  Distribution  of  the  IrUernal  Maxillary  Artery 

The  internal  maxillary  sends  branches  to  the  organs  of  mastication  and  deglutition,  to 
the  nasal  fossae,  to  the  bones  and  fibrous  membranes  of  the  cranium,  to  the  face,  and  to 
the  organ  of  hearing.     Its  different  branches  are  distributed  in  the  following  manner  : 

To  the  passive  instruments  of  mastication,  viz.,  the  jaws  and  teeth,  the  inferior  dental, 
the  superior  dental,  and  the  infra-orbital  arteries ;  to  the  active  organs  concerned  in  that 
process,  the  masseteric,  the  anterior  and  posterior  deep  temporal,  and  the  pterygoid  arteries. 

To  the  organs  of  deglutition,  viz.,  the  hard  and  soft  palate  and  the  pharynx,  the  supe- 
rior palatine,  the  small  meningeal,  the  vidian,  and  the  pterygo-palatine  arteries. 

To  the  nasal  fossae,  some  branches  of  the  infra-orbital,  and  the  whole  of  the  spheno- 
palatine artery ;  the  latter  vessel,  and,  consequently,  the  internal  maxillary  artery  also, 
are  very  large  in  those  animals  which  have  a  highly-developed  olfactory  apparatus. 

To  the  organ  of  hearing,  the  tympanic  artery,  those  branches  of  the  middle  meningeal 
which  enter  the  hiatus  Fallopii,  and  also  those  which  enter  the  canal  of  the  internal 
muscle  of  the  malleus. 

To  the  face,  viz.,  to  the  muscles  and  integuments,  the  buccal,  the  infra-orbital,  and  the 
merUal  arteries.  The  region  of  the  eye  is  the  only  part  not  supplied  by  the  internal  max- 
illary. 

To  the  bones  of  the  cranium,  and  to  the  dura  mater,  the  middle  and  the  small  meningeal 
arteries.  ^ 

The  Internal  Carotid. 

Dissection. — The  simplest  method  of  exposmg  this  vessel  is  to  make  the  section  for 
examining  the  pharynx.  The  carotid  canal  must  be  opened  with  a  chisel,  and  the  outer 
wall  of  the  cavernous  sinus  removed. 

The  internal  carotid  is  distributed  to  the  anterior  part  of  the  brain,  and  to  the  eye  and 
its  appendages. 

It  is  one  of  the  two  branches  into  which  the  common  carotid  divides  :  situated,  at  its 
origin,  on  the  outside  of  the  external  carotid,  it  passes  sometimes  vertically  upward,  par- 
allel to,  and  in  contact  with,  that  artery,  and  sometimes  behind  it,  by  crossing  it  at  an 
acute  angle  opposite  the  digastric  muscle ;  it  then  leaves  ine  external  carotid  to  pass 
deeply  into  the  triangular  space  between  the  pharynx  and  the  ramus  of  the  lower  jaw, 
and  reaches  the  base  of  the  cranium,  into  which  it  penetrates  by  the  carotid  canal.  After 
emerging  from  this  canal,  it  is  situated  in  the  cavernous  sinus,  upon  the  sides  of  the 
sella  turcica,  is  reflected  upward  on  the  inner  side  of  the  anterior  clinoid  process,  and 
terminates  by  dividing  into  three  branches. 

The  size  of  this  artery,  which  is  always  exactly  proportioned  to  that  of  the  brain,  is, 
in  the  adult,  equal  to  that  of  the  external  carotid  ;  in  the  infant  it  is  much  larger  (ramus 
grandior  carotidis,  Vesal.).  In  man,  cis  in  the  whole  series  of  animjds,  the  relative  size 
of  the  internal  and  external  carotids  is  determined  by  the  relative  development  of  the 
brain  and  the  face.  The  internal  carotid  is  remarkable  for  retaining  the  Same  diameter 
from  its  commencement  to  its  termination. 

Its  direction  is  generally  straight  until  it  reaches  the  base  of  the  cranium,  but  some- 
times it  describes  a  single  curve  immediately  after  its  commencement,  sometimes  sev- 
eral curves  having  opposite  directions.  At  the  base  of  the  cranium,  before  entering  the 
carotid  canaU  it  becomes  horizontal,  and  then  vertical  and  ascending. 

In  traversing  the  carotid  canal,  it  follows  the  angular  course  of  that  passage  ;  in  the 
cavernous  sinus,  it  passes  directly  forward  and  upward,  like  the  carotid  groove  ;  at  oth- 
er times  it  describes  two  distinct  curves ;  lastly,  on  the  inside  of  the  anterior  clinoid 
process,  it  is  reflected  directly  upward  and  a  little  backward.  The  double  curvature 
which  it  describes  in  traversing  the  carotid  canal  and  the  cavernous  sinus  has  been  weU 
compared  to  the  Roman  letter  S.    The  numerous  inflections  of  the  internal  carotid  form 


536  ANGEIOL06Y. 

one  of  the  most  decided  arguments  in  favour  of  the  opinion  that  the  use  of  these  wind- 
ings is  to  retard  the  passage  of  the  blood. 

Relations :  from  its  Origin  to  the  Base  of  the  Cranium. — At  its  origin,  the  internal  carot- 
id is  situated  as  superficially  as  the  termination  of  the  common  carotid,  and  is  crossed 
by  the  hypoglossal  nerve  and  the  occipital  artery ;  it  soon  passes  behind  the  external 
carotid,  and  becomes  deeper  and  deeper  Protected  by  its  position  m  the  triangular 
space,  which  is  bounded  on  the  inside  by  the  pharynx,  and  on  the  outside  by  the  ramus 
of  the  lower  jaw,  it  rests  behind  upon  the  vertebral  column,  from  which  it  is  separated 
by  the  praevertebral  muscles  and  aponeurosis  ;  it  is  in  relation  in  front  and  to  the  outer 
side  with  the  stylo-glossus  and  stylo-pnaryngeus  muscles,  which  pass  between  it  and 
the  external  carotid  ;  on  the  inside,  with  the  pharynx ;  and  on  the  outside  and  behind, 
with  the  internal  jugular  vein  The  ascending  pharyngeal  artery  is,  moreover,  in  rela- 
tion with  it  behind,  and  the  great  sympathetic  nerve  on  the  inside :  the  pneumogastric, 
glosso-pharyngeal,  and  h3rpoglossal  nerves  are  situated  behind  the  internal  carotid  at 
their  exit  from  the  cranium,  but  soon  get  to  its  outer  side,  between  it  and  the  internal 
jugular  vein. 

The  relation  of  the  artery  with  the  external  surface  of  the  pharynx  explains  how  this 
vessel  may  be  wounded  from  the  interior  of  that  cavit)'.  Sometimes  one  of  its  curves 
approaches  the  region  of  the  tonsil ;  and  this  may,  perhaps,  have  been  the  case  when 
the  artery  has  been  wounded  by  an  instrument  directed  transversely  outward  and  car- 
ried into  the  tonsil,  either  to  open  an  abscess  or  to  excise  the  gland. 

In  the  carotid  canal,  tae  artery  is  in  relation  with  the  nervous  filaments  ascending 
from  the  superior  cervical  ganglioa  A  very  thin  fibrous  lamina,  a  prolongation  of  the 
dura  mater,  separates  the  vessel  from  the  bony  walls  of  the  canal.  Its  proximity  to  the 
internal  ear  while  traversing  the  petrous  portion  of  the  temporal  bone,  is  probably  the 
cause  of  the  arterial  pulsations  which  are  heard  in  certain  cases. 

In  the  cavernous  sinus,  the  artery  is  applied  against  the  inner  wall  of  that  cavity,  and 
IS,  therefore,  placed  on  the  inner  side  of  the  nerves  which  pass  through  the  sinus,  and 
more  particularly  of  the  sixth  pair ;  it  is  said  that  the  artery  is  not  bathed  in  the  blood 
contained  in  the  sinus,  but  is  protected  from  it  by  a  very  thin  layer  of  membrane,  con- 
tinuous with  the  internal  coat  of  the  veins.  However  careful  I  may  have  been,  I  have 
never  succeeded  in  separating  this  membrane. 

On  the  inner  side  of  the  anterior  clinoid  process,  the  artery  is  upon  the  outer  side  of 
the  optic  nerve ;  and  at  the  point  where  it  emerges  from  the  dura  mater,  above  the  an- 
terior clinoid  process,  it  is  received  in  a  sheath  formed  by  the  arachnoid. 

Branches  of  the  Internal  Carotid. — On  the  outside  of  the  cranium  it  gives  offno  branch, 
excepting  in  a  few  cases  where  it  furnishes  the  ascending  pharyngeal,  or,  rather,  only 
a  supplementary  pharyngeal  brancl? ;  and,  lastly,  when  it  gives  off  the  occipital.  In  the 
carotid  canal,  it  sends  a  twig  into  the  cavity  of  the  tympanum  by  a  special  opening.  In 
the  cavernous  sinus,  it  furnishes  several  small  branches  {arterice  reccptaculi),  some  of 
which  are  reticulated,  and  distributed  to  that  portion  of  the  dura  mater  which  lines  the 
basilar  surface  of  the  occipital  bone,  and  to  the  walls  of  the  inferior  petrosal  sinus ; 
while  others  ramify  upon  the  pituitary  body,  the  fifth  pair  of  nerves,  and  the  adjacent 
portion  of  the  dura  mater :  a  larger  branch  anastomoses  with  the  middle  meningeal  ar- 
tery. 

Lastly,  on  the  inner  side  of  the  anterior  clinoid  process,  just  as  it  passes  above  that 
process,  the  internal  carotid  gives  off  in  front  a  remarkable  artery,  named  the  ophthalmic. 

The  Ophthalmic  Artery. 

Dissection. — Make  a  partial  injection,  either  from  the  common  or  internal  carotid. 
Remove  the  roof  of  the  orbit,  after  having  carefully  detached  the  integuments  and  peri- 
osteum of  the  frontal  region ;  leave  a  small  bridge  of  bone  on  the  inner  part  of  the 
margin  of  the  orbit  for  the  supra-orbital  artery,  or,  rather,  open  the  supra-orbital  fora- 
men and  disengage  the  artery  from  it.  Dissect  the  muscles  of  the  eye  with  great  care, 
preserving  all  the  vessels  which  present  themselves.  The  study  of  the  branches  of  the 
ophthalmic  artery,  which  are  distributed  to  the  ball  of  the  eye,  requires  a  perfect  knowl- 
edge of  that  organ. 

This  artery  is  principally  destined  for  the  eye  and  its  appendages,  and  is  less  remark- 
able for  its  size,  which  is  inconsiderable,  than  for  the  number  of  its  branches.  Imme- 
diately after  its  origin,  it  enters  the  optic  foramen  {b,  fig.  207),  on  the  outer  side  of  and 
below  the  optic  nerve.*  The  artery  is  at  first  contained  in  the  same  sheath  as  the 
nerve,  but,  soon  escaping  from  it,  penetrates  into  the  orbit  between  the  abducens  oculi 
nerve  and  the  external  rectus  muscle  of  the  eye,  turns  inward  and  crosses  the  optic 

'  A  very  remarkable  variety  in  the  origin  of  the  ophthalmic  artery  is  that  m  which  this  artery  arises  by  a 
common  trunk  with  the  middle  meningeal  or  arteria  media  dura  matris,  which  is  a  branch  of  the  intenial 
maxillary.  In  a  case  of  this  kind,  which  has  been  communicated  to  me  by  M.  Dubreuil,  the  ophthalmic  ar- 
tery arose  from  the  anterior  branch  of  the  meningeal ;  when  this  branch  reached  the  canal  at  the  anterior  in 
ferior  angle  of  the  parietal  bone,  it  entered  the  orbit  by  the  external  extremity  of  the  foramen  lacerum  or- 
bitale,  and  successively  gave  off  the  branches  furnished  by  the  ophthalmic  artery. 


THE    OPHTHALMIC    ARTERY.  527 

nerre,  sometimes  at  right  angles  and  sometimes  obliquely,  and  is  then  placed  above  the 
nerve.    Having  reached  the  inner  wall  of  the  orbit,  it  again  changes  p..    ^^^ 

its  direction,  passes  horizontally  and  in  a  slightly  tortuous  manner  ^' 

along  the  lower  border  of  the  superior  oblique  muscle  of  the  eye, 
and  terminates  by  bifurcating  at  the  margin  of  the  orbit.  Not  un- 
frequently,  the  ophthalmic  artery,  immediately  after  its  origin,  is 
placed  on  the  inner  side  of  and  below  the  optic  nerve,  and  then  pass- 
es directly  forward  along  the  inner  side  of  that  nerve  ;  so  that,  in 
these  cases,  the  nerve  and  artery  do  not  cross  each  other. 

The  ophthalmic  artery  gives  off  a  great  number  of  branches, 
which,  according  to  their  origin,*  may  be  divided  into  those  ari- 
sing on  the  outside  of  the  optic  nerve,  viz.,  the  lachrymal  artery 
and  the  central  artery  of  the  retina ;  those  arising  above  the  nerve, 
viz.,  the  supra-orbital,  the  short  ciliary,  the  middle  or  anterior  ciliary, 
the  superior  and  the  inferior  muscular  arteries ;  those  arising  on  the  ^5^ ' 
inner  side  of  the  optic  nerve,  viz.,  the  posterior  and  anterior  eth- 
moidal and  the  inferior  and  superior  palpebral  arteries ;  in  all,  eleven  branches,  to  which  may 
be  added  the  terminal  branches,  viz.,  the  nasal  and  the  frontal  arteries.  It  is  well  to  remark, 
that  the  origins  of  most  of  the  above-named  branches  are  subject  to  extreme  variety. 

Branches  arising  on  the  Outer  Side  of  the  Optic  Nerve. — The  lachrymal  artery  {c,Jig. 
207),  one  of  the  largest  branches  of  the  ophthahnic,  arises  immediately  before  the  en- 
trance of  the  latter  into  the  orbit.  Not  unfrequently  it  is  given  off  from  the  middle  me- 
ningeal artery. 

The  lachrymal  artery  passes  from  behind  forward  along  the  outer  wall  of  the  orbit, 
between  the  periosteum  and  the  external  rectus  muscle,  and  enters  the  lachrjTnal  gland 
(/),  supplying  it  with  a  great  number  of  branches.  Emerging  from  the  gland  very  much 
reduced  in  size,  it  terminates  partly  in  the  conjunctiva,  and  partly  in  the  structures  com- 
posing the  upper  eyelid. 

In  its  course  it  sometimes  gives  off  a  small  meningeal  branch,  which  passes  back- 
ward through  the  sphenoidal  fissure,  and  enters  the  dura  mater,  in  which  it  anastomoses 
with  the  middle  meningeal  artery.  This  branch  may  be  considered,  in  some  subjects, 
as  one  origin  of  the  lachrymal  artery ;  a  condition  that  leads  to  those  cases  in  which 
the  lachrymal  artery  arises  from  the  middle  meningeal.  It  often  gives  off  a  long  cihary 
artery,  and  always  some  twigs  to  the  neurilemma  of  the  optic  nerve,  and  muscular 
branches  to  the  levator  palpebrse  superioris  and  the  superior  rectus  ;  lastly,  it  furnishes 
a  muscular  branch,  the  malar,  which  perforates  the  malar  bone,  and  anastomoses  in  the 
temporal  fossa  with  the  anterior  deep  temporal  artery,  and  upon  the  malar  bone  itself 
with  the  transversalis  faciei. 

The  central  artery  of  the  retina  {artena  centralis  renna,  t),  quite  distinct  from  the  twigs 
supplied  to  the  neurilemma  of  the  optic  nerve,  is  an  extremely  delicate  vessel :  it  arises 
either  from  the  ophthalmic,  or  from  one  of  the  ciliary  arteries,  penetrates  obliquely  into 
the  substance  of  the  nerve,  runs  along  its  centre  from  behind  forward,  enters  into  the 
globe  of  the  eye,  and  expands  in  diverging  ramifications,  which  are  applied  to  the  inter- 
nal surface  of  the  retina,  and  accompany  it  as  far  as  the  ciliary  processes.  A  branch 
very  distinct  from  those  just  mentioned  traverses  the  vitreous  body  from  behind  forward, 
in  the  axis  of  the  eye,  and  reaches  the  capsule  of  the  crystalline  lens,  after  having  fur 
nished  some  extremely  fine  twigs  to  the  hyaloid  membrane. 

Branches  arising  above  the  Optic  Nerve. — The  supra-orbital  or  superciliary  artery  (d) 
arises  from  the  ophthalmic  as  that  vessel  is  crossing  the  optic  nerve  ;  it  is  sometimes 
given  off  from  the  lachrymal.  It  is  very  variable  in  size,  and  appears  in  certain  cases 
to  be  partially  replaced  by  the  orbital  branch  of  the  temporal,  or  by  the  frontal  branch 
of  the  ophthalmic.  It  passes  horizontally  between  the  periosteum  of  the  roof  of  the  or- 
bit and  the  levator  palpebrae  superioris,  accompanied  by  the  frontal  nerve ;  it  escapes 
from  the  orbit  at  the  superciliary  notch,  is  reflected  over  it  as  over  a  pulley,  ascends 
vertically,  and  divides  into  two  branches,  one  of  which  passes  upward  between  the  skin 
and  the  orbicularis  and  occipito-frontalis  muscles,  and  the  other  is  situated  between  the 
muscles  and  the  periosteum,  and  ramifies  in  that  membrane.  The  sub-cutaneous  branch 
often  divides  into  an  internal  and  an  external  twig.  It  is  also  said  constantly  to  furnish 
a  branch  to  the  diploe  of  the  frontal  bone,  as  it  is  passing  through  the  superciliary  notch. 
It  appears  to  me  that  this  branch  is  often  wanting. 

The  ciliary  arteries  may  be  divided  into  the  posterior  or  short,  the  mjiddle  or  long,  and 
the  anterior. 

The  posterior  cuiary  arteries  (r)  distributed  to  the  choroid  coat  and  the  ciliary  processes 
(arteres  uveales,  Chauss.)  are  irregular  in  number  which  is  stated  to  be  thirty,  or  even 

*  The  branches  given  off  by  the  ophthalmic  artery  might  be  more  philosophically  divided  as  follows  :  Ist. 
Those  -which  are  destined  to  the  globe  of  the  eye,  viz.,  the  arteries  of  the  retina,  the  short  cihary  or  choroi- 
dian,  the  middle  or  long  ciliary,  and  the  anterior  ciliary  ;  2d.  Those  which  are  distributed  to  the  parts  con- 
tained in  the  orbital  cavity,  lachrymal  and  muscular  arteries  ;  3d.  Those  which  are  on  the  outside  of  tha 
orbital  cavity,  the  palpebral,  sub-orbital,  ethmoidal,  frontal,  and  nasal  artenes. 


628  ANGEIOLOGY. 

forty;  they  arise  from  two  trunks  :  one  inferior,  which  is  given  off  from  the  ophthalmic 
artery  on  the  outer  side  of  the  optic  nerve  ;  the  other  is  superior,  and  arises  above  that 
nerve.  Not  unfrequently  the  lachrymal  artery  gives  off  the  inferior  long  ciliary  trunk. 
They  run  in  a  very  tortuous  course  along  the  optic  nerve,  and,  having  reached  the  ball 
of  the  eye,  twist  spirally  and  immediately  expand  into  a  tuft  of  tortuous  ramusculi, 
which  surround  the  optic  nerve,  perforate  the  sclerotic  coat  around  the  entrance  of  the 
nerve,  and  then  ramify,  as  will  be  elsewhere  stated,  in  the  choroid  coat  and  ciliary  pro- 
cesses. 

The  middle  or  long  ciliary  arteries  (arteres  iriennes,  Chauss.),  which  are  distributed  to 
the  iris,  are  two  in  number,  an  internal  and  an  external ;  they  perforate  the  sclerotic  at 
some  distance  from  the  optic  nerve,  and  pass  between  the  sclerotic  and  the  choroid 
membrane  on  the  sides  of  the  eyeball.  Having  reached  the  ciliary  ring,  each  of  them 
divides  into  two  branches,  which  anastomose  together,  and  form  the  great  vascular  circle 
of  the  iris.  Numerous  radiating  branches  proceed  from  all  points  of  the  inner  border  of 
this  circle  towards  the  free  margin  of  the  iris,  where  they  subdivide  and  anastomose  to 
form  the  lesser  vascular  circle  of  that  membrane. 

The  anterior  ciliary  arteries  are  irregular  in  number,  and  are  derived  from  the  muscu- 
lar branches,  and  sometimes  from  the  lachrymal  and  infra-orbital ;  they  give  some 
branches  to  the  conjunctiva,  penetrate  the  sclerotic  at  a  short  distance  from  the  cornea, 
and  terminate  in  the  great  circle  of  the  iris. 

The  muscular  arteries  are  two,  viz.,  the  superior  and  the  inferior.  The  superior  is  the 
smaller  :  it  is  often  wanting,  and  is  then  replaced  by  branches  from  the  lachrymal,  infra- 
orbital, or  ciliary  arteries.  It  is  distributed  to  the  levator  palpebrae  superioris,  the  supe- 
rior rectus,  and  the  obliquus  superior.  The  inferior,  which  always  exists,  passes  from 
behind  forward  between  the  optic  nerve  and  the  inferior  rectus,  gives  off  most  of  the 
anterior  ciliary  arteries,  and  is  distributed  to  the  external  and  inferior  recti,  and  to  the 
obliquus  inferior.  Sometimes  the  inferior  muscular  is  not  entirely  distributed  to  the  mus- 
cles, but  forms  an  anastomotic  arch  with  the  infra-orbital  branch  of  the  internal  maxillary. 

Branches  arising  on  the  inner  Side  of  the  Optic  Nerve. — The  ethmoidal  arteries  are  two, 
viz.,  the  anterior  and  the  posterior.  The  posterior  ethmoidal  (e)  is  given  off  the  first 
from  the  ophthalmic,  and  is  sometimes  as  large  as  the  continuation  of  that  artery :  at  oth- 
er times  merely  a  trace  of  it  exists.  It  runs  from  without  inward,  passes  through  the 
posterior  internal  orbital  canal  to  reach  the  ethmoidal  groove  within  the  cranium,  and 
then  divides  into  a  meningeal  and  a  nasal  branch.  The  meningeal  ramifies  in  the  dura 
mater,  particularly  in  the  falx  cerebri ;  the  nasal  branch  enters  the  nasal  fossa,  through 
the  foramina  of  the  cribriform  plate,  and  anastomoses  with  the  ultimate  divisions  of  the 
spheno-palatine  artery. 

The  anterior  ethmoidal  (/)  is  mversely  proportioned,  as  regards  size,  lo  the  posterior 
artery,  which  is  sometimes  replaced  by  it ;  it  enters  the  cranium  through  the  anterior 
internal  orbital  canal,  and  divides  into  a  meningeal  branch,  distributed  upon  the  fabc  cer- 
ebri, and  a  nasal  branch,  which  penetrates  the  olfactory  cavities  by  the  foramina  of  the 
cribiform  plate.     The  branches  to  the  falx  are  remarkably  tortuous. 

The  palpebral  arteries  are  divided  into  the  superior  and  the  inferior.  Both  arise  from 
the  ophthalmic,  opposite  the  cartilaginous  pulley  of  the  superior  oblique.  Sometimes 
they  arise  by  a  common  trunk.  Most  commonly  the  inferior  palpebral  is  given  off  a  lit- 
tle before  the  superior.  Sometimes  the  superior  is  so  large  that  it  appears  to  result 
from  a  division  of  the  ophthalmic  itself  into  two  equal  branches. 

The  inferior  palpebral  passes  vertically  downward,  behind  the  tendon  of  the  orbicularis 
muscle,  proceeds  outward  to  reach  the  lower  eyelid,  along  the  whole  length  of  which  it 
runs  in  the  form  of  an  arch  without  any  winding,  and  is  gradually  lost  at  the  external 
canthus  or  angle  of  the  eyelids. 

The  vascular  arch  thus  formed,  the  inferior  palpebral,  is  situated  between  the  muscular 
fibres  of  the  eyehd  and  the  tarsal  cartilage,  immediately  below  the  free  border  of  that 
cartilage. 

At  the  point  where  it  enters  the  eyelid,  it  gives  off  a  very  remarkahle  branch,  which 
anastomoses  with  the  orbital  branch  of  the  infra-orbital  artery.  From  the  arch  of  anas- 
tomosis a  branch  arises,  which  enters  the  nasal  duct  (branch  of  the  nasal  duct),  and  ram- 
ifies in  the  mucous  membrane  of  that  passage,  as  far  as  the  inferior  meatus. 

The  superior  palpebral  passes  downward  behind  the  orbicularis  palpebrarum,  and,  having 
reached  the  superior  punctum  lachrymale,  is  reflected  outward,  between  the  muscular 
fibres  and  the  tarsal  cartilage,  immediately  above  its  free  border,  along  which  it  forms 
an  arch,  and  terminates  by  anastomosing  with  a  palpebral  branch  derived  from  the  su- 
perficial temporal. 

Terminal  Branches  of  the  Ophthalmic. — At  the  anterior  extremity  of  the  angle  formed 
by  the  upper  and  internal  walls  of  the  orbit,  the  ophthalmic  artery  terminates  by  divi- 
ding into  a  nasal  and  a  frontal  branch. 

The  7iasal  branch  varies  in  size,  and  is  often  larger  than  the  ophthalmic  artery  itself, 
so  that  some  anatomists  have  regarded  it  as  a  branch  of  the  facial,  with  which  it  always 
anastomoses.     It  emerges  from  the  orbit  above  the  tendon  of  the  orbicularis,  and  hav' 


UEttEBRAL    BRANCHES    OF    THE    INTERNAL   CAROTID. 


(ng  given  off  a  small  branch,  which  afterward  enters  the  groove  in  the  os  unguis,  to  be 
distributed  to  the  mucous  membrane  of  the  lachrymal  sac,  it  divides  into  two  branches  : 
one,  named  the  angular  artery,  runs  in  the  groove  formed  by  the  nose  and  cheek,  be- 
tween the  pyramidalis  nasi  and  the  levator  labii  superioris  alaeque  nasi ;  it  is  accompa- 
nied by  the  vein,  which  lies  to  its  outer  side,  and  it  is  continuous  with  the  facial  artery, 
without  any  line  of  demarcation,  the  two  vessels  inosculating  so  completely,  that  it  is 
impossible  to  define  their  respective  limits :  the  other  branch,  the  dorsal  artery  of  the 
nose,  runs  along  the  dorsum  of  the  nose,  and  terminates  opposite  each  ala  by  anastomo- 
sing with  its  corresponding  artery.  These  two  divisions  of  the  nasal  branch  of  the  oph- 
thalmic are  sub-cutaneous,  and  give  off  numerous  ramifications,  which  cover  the  whole 
surface  of  the  nose. 

The  frontal  branch  is  smaller  than  the  nasal,  and  generally  smaller  than  the  supra- 
orbital or  superciliary ;  it  passes  upward  upon  the  forehead,  parallel  to  the  supra-orbital, 
with  which  it  communicates  above  by  a  transverse  branch ;  it  divides  into  sub-cutaneous 
twigs,  situated  between  the  skin  and  the  muscles,  and  into  muscular  and  periosteal  t\yigs. 

Summary  of  the  Distribution  of  the  Ophthalmic  Artery, — The  ophthalmic  sends  branches 
to  the  ball  of  the  eye,  to  its  appendages,  viz.,  the  muscles,  eyelids,  and  lachrymal  appa- 
ratus, to  the  frontal  region,  and  to  the  nose  and  nasal  fossae. 

To  the  ball  of  the  eye  it  gives  the  arteria  centralis  retinae,  which  supplies  the  retina, 
the  hyaloid  membrane,  and  the  capsule  of  the  crystalline  lens ;  the  posterior,  middle, 
and  anterior  ciliary  arteries,  which  are  distributed  to  the  choroid  membrane,  the  ciliary 
processes,  and  the  iris. 

It  supplies  proper  muscular  branches,  and  also  twigs  from  its  other  branches,  to  the 
muscles  of  the  eye. 

To  the  eyelids  it  gives  off  the  palpebral  arteries.  To  the  lachrymal  apparatus  it  sup- 
plies the  lachrymal  artery  for  the  gland,  and  the  two  branches  for  the  lachrymal  sac  and 
the  nasal  duct. 

The  frontal  region  receives  its  frontal  and  supra-orbital  branches  ;  the  nose,  the  nasal 
branch,  and  the  nasal  fossae,  the  anterior  and  posterior  ethmoidal  arteries. 

The  Cerebral  Branches  of  the  Internal  Carotid  Artery. 
When  the  internal  carotid  has  given  off  the  ophthalmic  artery,  it  enters  (c,  fig,  208>  a 


Fig.  208. 


deep  fossa  seen  on  the  base  of  the  brain  at  the  inner 
end  of  the  fissure  of  Sylvius,  and  immediately  divides 
into  three  branches,  which  spread  out  from  each  other. 

Of  these  three  branches,  the  anterior  is  called  the 
anterior  cerebral,  or  artery  of  the  corpus  callosum ;  the 
external  is  named  the  middle  cerebral,  or  artery  of  the 
fissure  of  Sylvius ;  and  the  third,  or  posterior,  is  the 
posterior  communicating  artery. 

Not  unfrequently  the  carotid  gives  origin  to  the  pos- 
terior cerebral  artery,  from  which,  in  that  case,  the 
posterior  communicating  artery  is  then  given  off,  and 
immediately  joins  the  anterior  extremity  of  the  basi-  |^/ 
lar  artery. 

The  Anterior  Cerebral  Artery.  Dissection.  —  The 
study  of  these  arteries  requires  no  preparation ;  it  is 
sufficient  to  overturn  the  brain  in  a  manner  which 
will  bring  its  base  into  view.  Each  artery  will  be 
recognised  by  the  following  description :  This  vessel 
{d  d,  fig.  208),  also  called  the  artery  of  the  corpus  cal- 
losum, passes,  immediately  after  its  origin,  forward 
and  inward,  towards  the  median  line,  and  thus  reaches  the  longitudinal  fissure  between 
the  right  and  left  anterior  lobes  of  the  brain.  There  it  approaches  its  fellow  of  the  op- 
posite side,  and  communicates  with  it  by  a  transverse  branch,  which  passes  at  right  an- 
gles between  them.  This  anastomotic  branch  (a),  so  remarkable  for  its  size,  shortness. 
and  direction,  is  called  the  anterior  communicating  artery ;  instead  of  one,  there  are  some- 
times two  smaller  branches  ;  sometimes  it  is  so  short  that  the  two  anterior  cerebral  ar- 
teries may  be  said  to  be  applied  to  each  other,  and  blended  together  at  this  point :  most 
commonly  it  is  from  one  to  two  lines  in  length,  and  it  then  gives  off  some  small  twigs. 
which  penetrate  into  the  third  ventricle. 

^Lfter  communicating  in  this  manner,  the  anterior  cerebral  arteries  become  parallel, 
run  from  behind  forward,  turn  upward  in  front  of  the  anterior  extremity  of  the  corpus 
callosum,  and  then  run  backward  upon  its  upper  surface,  as  far  as  its  posterior  extremity, 
describing  a  curve,  which  exactly  corresponds  with  that  of  the  corpus  callosum  itself 

Before  turning  over  the  anterior  border  of  the  corpus  callosum,  the  anterior  cere 
bral  arteries  give  off  some  ramuscuh  to  the  optic  and  olfactory  nerves,  to  the  third  ven- 
tricle, and  the  adjacent  part  of  the  anterior  lobe  of  the  brain,"and  also  a  series  of  large 
branches,  which  are  distributed  to  the  inferior  surface  of  the  samr  lobe.     At  the  poin* 

X  X  X 


530  ANGEIOLOGY. 

where  the  arteries  are  reflected,  and  also  along  the  upper  surface  of  the  corpus  callosum, 
large  branches  arise  from  the  convexity  of  the  curve  described  by  these  vessels,  and 
ramify  upon  the  inner  surface  of  the  two  hemispheres  :  the  anterior  branches  run  from 
behind  forward,  and  the  others  from  before  backward,  and  from  below  upward ;  most  of 
them  reach  the  convex  surface  of  the  brain.  Some  capillary  twigs  proceed  from  the  con- 
cavity of  the  curve,  and  penetrate  the  substance  of  the  corpus  callosum. 

We  may  regard  as  the  termination  of  each  anterior  cerebral  artery  a  very  small  branch 
which  continues  in  the  same  course,  reaches  the  posterior  extremity  of  the  corpus  callo- 
sum, is  there  reflected  downward,  and  terminates  in  the  adjacent  convolutions  of  the 
brain. 

The  Middle  Cerebral  Artery. — This  is  larger  than  the  preceding  vessel ;  it  passes  (/, 
Jig.  208)  outward  and  backward  to  enter  the  hssure  of  Sylvius,  having  previously  given 
off  a  great  number  of  rather  large  branches,  which  run  perpendicularly  upward  into  the 
very  thin  layer  of  cerebral  substance  situated  at  the  junction  of  the  longitudinal  fissure 
of  the  brain  with  the  fissure  of  Sylvius.* 

As  soon  as  the  middle  cerebral  artery  has  entered  the  fissure  of  Sylvius,  it  divides  into 
three  branches  :  an  anterior,  which  is  applied  to  the  anterior  lobe ;  a  posterior,  which 
lies  upon  the  middle  lobe  ;  and  a  median  branch,  which  corresponds  to  the  small  lobe 
that  is  concealed  within  the  fissure  :  they  all  follow  the  direction  of  this  fissure,  and  are 
concealed  within  it,  but  soon  emerge  so  as  to  ramify  upon  the  convolutions  and  anfrac- 
tuosities  of  the  brain,  anastomosing  with  each  other,  and  with  the  branches  of  the  ante- 
rior and  posterior  cerebral  arteries. 

It  is  of  importance  to  remark,  and  this  observation  applies  to  all  the  cerebral  arteries, 
that  the  arterial  ramifications  destined  for  the  surface  of  the  brain  are  extremely  tortuous, 
that  they  dip  into  the  anfractuosities,  and  cover  the  free  borders  and  the  two  surfaces  of 
the  convolutions,  between  which  they  are  situated  ;  that  they  ramify  very  freely,  and  run 
a  very  extensive  course  ;  and  that  they  do  not  divide  gradually  into  smaller  and  smaller 
branches,  but  that  bundles  of  very  fine  capillary  vessels  arise  from  every  part  of  the  cir- 
cumference of  vessels  of  a  certain  size,  and  immediately  penetrate  the  cerebral  substance. 

The  Posterior  Communicating  Artery,  or  Communicating  Artery  of  Willis. — This  artery 
varies  exceedingly  in  size,  being  generally  small,  but  sometimes  forming  the  largest  di- 
vision of  the  internal  carotid.  It  arises  from  the  back  of  the  carotid,  runs  from  before 
backward  (?),  and  terminates  in  the  posterior  cerebral  branch  of  the  basilar  artery.  In 
certain  cases,  the  communicating  artery  of  Willis  may  be  regarded  as  the  chief  origin 
of  the  posterior  cerebral,  which  then  seems  to  result  from  the  union  of  this  communica- 
ting artery  with  the  anterior  bifurcation  of  the  basilar. 

The  Choroid  Artery. — A  very  small  but  constant  branch  (s)  arises  from  the  back  of  the 
internal  carotid,  on  the  outer  side  of  the  communicating  artery  of  Willis.  This  is  the 
artery  of  the  choroid  plexus,  which  passes  backward  and  outward,  along  the  optic  tract, 
and,  consequently,  along  the  eras  cerebri,  to  both  of  which  it  sends  branches,  and  then  en- 
ters the  lateral  ventricle  at  the  anterior  extremity  of  the  great  transverse  fissure  of  the 
brain,  gives  twigs  to  the  hippocampus  major  and  corpus  fimbriatum,  and  terminates  in 
the  choroid  plexus,  t 

Summary  of  the  Distribution  of  the  Common  Carotid  Arteries. 

The  common  carotids  are  distributed  to  the  head,  and  to  the  organs  which  occupy  the 
front  of  the  neck. 

The  internal  carotid  belongs  exclusively  to  the  brain,  and  to  the  organs  of  vision ;  and 
hence,  doubtless,  at  least  in  part,  arises  that  intimate  relation  between  the  condition  of 
the  brain  and  of  the  eye,  which  is  expressed  by  the  common  saying,  that  the  eye  is  the 
mirror  of  the  soul. 

Although  the  size  of  the  internal  carotid  is  almost  always  in  proportion  to  that  of  the 
brain,  yet  this  artery  is  not  the  only  one  by  which  that  organ  is  supplied  with  blood.  The 
vertebral  artery,  a  large  branch  of  the  subclavian,  completes  the  arterial  system  of  the 
brain  ;  and  the  fact  of  an  artery,  principally  destined  for  the  upper  extremity,  also  send- 
ing a  branch  to  the  brain,  proves  that  there  is  nothing  peculiar  in  the  quality  of  the  blood 
transmitted  to  the  encephalon. 

We  have  already  seen  that  the  ophthalmic  artery  communicates  by  its  nasal  branch 
with  the  facial  artery,  and  by  its  inferior  palpebral  branch  with  the  infra-orbital  branch 
of  the  internal  maxilleury.  But  the  internal  carotid  has  no  direct  communication  with  the 
external,  unless  when  it  gives  origin  to  the  ascending  pharyngeal  and  the  occipital  arter- 
ies. I  may  remark,  however,  that  some  meningeal  branches  are  given  off  by  the  inter- 
nal carotid  within  the  cavernous  sinus. 

The  external  carotid  differs  from  the  internal,  in  giving  origin  to  a  very  great  number 
of  branches,  which  are  distributed  to  the  face,  to  the  parietes  of  the  cranium,  to  the  or- 
gans of  respiration,  and,  lastly,  to  the  organs  of  digestion. 

The  facial  branches  may  be  divided  into  the  superficial  and  the  deep-seated. 

*  We  shall  see  hereafter  that  this  region  of  the  brain  belongs  to  the  corpus  striatum. 
.-  ^      f  See  vertebral  artery  (p.  533),  for  the  completion  of  the  arterial  system  of  the  enceohalon. 


ARTERY   OF   THE  UPPER  EXTREEITY.  531 

The  superficial  arteries  of  the  face  are  derived  from  many  sources.  The  principal  one 
is  furnished  by  the  facial  or  external  maxillary  ;  the  others  are  the  transverse  artery,  or 
transverse  arteries  of  the  face,  coming  from  the  temporal ;  the  nasal,  a  descending  branch 
of  the  ophthalmic  ;  the  buccal,  masseteric,  infra-orbital,  and  mental— all  derived  from 
the  internal  maxillary.  The  arteries  of  the  right  side  communicate  very  freely  and  fully 
with  those  of  the  left ;  and  on  each  side,  branches  from  the  different  sources  communi 
cate  as  freely  with  each  other ;  so  that,  in  hemorrhage  from  any  of  them,  the  injured 
vessel  must  be  tied  on  both  sides  of  the  wound.  I  may  call  attention  to  the  abundance 
of  arterial  vessels  in  the  face,  and  to  the  number  and  size  of  the  muscular  and  cutaneous 
branches  ;  this  is  evidently  connected  with  the  extreme  susceptibility  of  the  skin  of  tliis 
region,  the  existence  of  the  hair-bulbs,  and  the  action  of  the  muscles  in  giving  expression 
to  the  features. 

The  deep  arteries  of  the  face  are  principally  derived  from  the  internal  maxillary.  Thus, 
the  spheno-palatine  supplies  the  nasal  fossae  :  some  branches  of  the  infra-orbital  enter 
the  orbit.  We  shall  afterward  allude  to  the  branches  which  are  furnished  to  the  buccal 
cavity  and  the  zygomatic  and  spheno-maxillary  fossae.  Lastly,  the  superficial  and  deep 
arteries  of  the  face  are  united  by  numerous  anastomoses. 

The  first  set  of  cranial  branches,  derived  from  the  external  carotid,  are  the  arteries  of 
the  hairy  scalp,  viz.,  the  occipital,  temporal,  posterior  auricular,  supra-orbital,  and  frontal. 
With  regard  to  these  arteries,  it  is  important  to  notice  their  large  size,  which  is  connect- 
ed with  the  great  vitality  of  the  skin  of  the  head,  and  with  the  existence  of  the  bulbs  of 
the  hair ;  also,  that  they  are  extremely  tortuous,  which  appears  to  me  to  be  in  corre- 
spondence with  the  great  number  of  branches  which  they  give  off;  and,  lastly,  that  they 
are  situated  in  the  dense  cellular  tissue  which  connects  the  skin  with  the  muscles  and 
the  epicranial  aponeurosis. 

Besides  these,  small  branches  are  found  upon  the  pericranium,  under  the  muscles  and 
epicranial  aponeurosis  :  they  are  seen  on  the  forehead,  where  they  arise  from  the  fron- 
tal and  infra-orbital  arteries,  and  also  in  the  temporal  region,  where  they  axe  C2illed  the 
deep  temporals  ;  these  branches  are  both  periosteal  and  muscidar. 

The  second  set  of  branches  to  the  cranial  parietes  are  arteries  of  the  interior  of  the  cra- 
nium, viz.,  the  meningeal,  the  chief  of  which  is  the  middle  meningeal,  a  branch  of  the  in- 
ternal maxillary  :  the  others,  or  small  meningeals,  enter  through  most  of  the  foramina 
at  the  base  of  the  cranium.  Among  these  latter  we  would  mention  the  meningeal 
branches  of  the  ascending  pharyngeal  artery,  and  meningeal  branches  from  the  ethmoidal 
arteries,  to  which  may  be  added  some  small  twigs  given  off  from  the  internal  carotid, 
while  enclosed  in  the  cavernous  sinus. 

We  may  also  refer  the  arteries  of  the  organ  of  hearing  to  those  of  the  cranial  pirietes. 
They  are  the  posterior  auricular  and  the  anterior  auricular,  which  are  distributed  to  the 
pinna  and  to  the  external  meatus  ;  the  tympanic,  which  passes  through  the  fissure  of 
Glasserus,  and  a  small  branch  of  the  middle  meningeal,  which  enters  through  the  hiatus 
Fallopii. 

The  branches  of  the  external  carotid  distributed  to  the  orguns  of  digestion  belong  to  the 
following  parts : 

To  the  organs  of  mastication,  viz.,  the  alveolar,  the  infra-orbital,  and  the  inferior  den- 
tal arteries,  which  go  to  the  teeth  and  the  jaws  ;  the  superior  palatine,  which  supplies 
the  roof  of  the  palate  ;  and,  lastly,  the  deep  temporal,  the  masseteric,  and  the  pterygoid, 
which  are  distributed  to  the  muscles  of  mastication.  To  the  salivary  organs  :  thus,  the 
parotid  receives  its  branches  from  the  external  carotid  and  the  temporal ;  the  sub-max- 
illary gland  from  the  facial ;  and  the  sub-lingual  gland  from  the  sub-lingual  branch  of  the 
lingual  artery.  To  the  velum  pdati  and  the  tonsils  we  find  the  ascending  or  inferior 
palatine  branch  of  the  facial  artery,  the  superior  palatine  branch  of  the  internal  maxillary, 
and  the  ascending  pharyngeal.  To  the  pharynx,  the  pharyngeal  twigs  from  the  superior 
thyroid,  the  ascending  pharyngeal,  the  pterygo-palatine  or  superior  pharyngeal,  and  the 
vidian  from  the  internal  maxillary,  and  the  inferior  palatine  branch  of  the  facial.  To 
the  oesophagus  there  are  the  descending  oesophageal  branches  of  the  superior  thjToid. 

The  branches  given  by  the  external  carotid  to  the  air-passages  are  the  superior  and  infe- 
rior laryngeal,  from  the  superior  thyroid  artery,  which  is  essentially  distributed  to  the 
thyroid  gland. 

Aeteet  of  the  Uppee  Extremity. 

A  aiagle  arterial  trunk,  called  the  brachial  trunk  ( Chaussier),  is  destmed  for  the  upper 
extremity.  On  the  left  side  it  arises  directly  from  the  arch  of  the  aorta,  and  on  the 
right  side  from  the  innominate  artery ;  it  emerges  from  the  thorax,  between  the  first  rib 
and  the  clavicle,  traverses  the  axilla,  runs  along  the  inner  side  of  the  arm,  passes  in  front 
of  the  elbow-joint,  and  divides  into  two  branches,  which  supply  the  forearm  and  the  hand. 

As  the  brachial  trunk  has  some  highly  important  relations  during  its  course,  and, 
moreover,  furnishes  a  very  great  number  of  branches,  it  has  been  artificially  divided,  in 
order  to  facilitate  its  study :  each  of  the  divisions  has  received  a  particular  name,  ac- 
cording to  the  region  through  which  it  passes  :  thus,  the  arterv  of  the  upper  extremity 


532  ANGEIOLOGY. 

is  called  successively  the  sub-clavian,  the  axillary,  and  the  hwneral  artery ,  and  its  termi- 
nal divisions  are  named  the  radial  and  ulnar  arteries. 

The  Brachio-cephalic  Artery. 

The  brachio-cephalic  or  innominate  artery  {arteria  anonyma  of  many  authors,  e,fig.  198) 
is  the  common  trunk  of  the  right  sub-clavian  and  right  common  carotid  arteries,  and  has 
in  turns  been  regarded  as  a  portion  of  the  carotid,  and  as  a  part  of  the  sub-clavian.  It 
arises  from  the  aorta,  at  the  point  where  that  vessel  changes  its  direction  from  vertical 
to  horizontal.  It  is  situated  in  front  and  to  the  right  of  the  other  arteries  given  off  from 
the  arch  of  the  aorta.  It  is  from  one  inch  to  fifteen  lines  in  length.  It  is  directed  ob- 
liquely upward  and  outward. 

Relations- — In  front  of  the  mnommate  artery  is  the  sternum,  beyond  the  upper  end  of 
which  the  artery  almost  always  projects,  and  from  which  it  is  separated  by  the  left 
brachio-cephalic  vein,  by  the  remains  of  the  thymus,  and  by  the  sternal  attachments  of 
the  stemo-hyoid  and  sterno-thyroid  muscles.  Behind,  it  is  in  relation  with  the  trachea, 
which  it  crosses  obliquely ;  on  the  outer  side,  with  the  pleura  and  mediastinum,  which 
separate  it  from  the  lungs  ;  on  its  inner  side  is  the  left  common  carotid,  from  which  it  is 
separated  by  a  triangular  interval,  in  which  the  trachea  is  seen. 

From  a  knowledge  of  these  relations,  modem  surgeons  have  succeeded  in  applying  a 
ligature  to  the  innominate  artery.  Its  relations,  however,  vary  in  different  individuals. 
In  some  cases  almost  the  whole  length  of  the  vessel  projects  beyond  the  sternum ;  and 
it  is  then  extremely  accessible,  either  to  accidental  wounds,  or  to  the  surgeon  in  the  ap 
plication  of  a  ligature.  It  has  been  thought  that  the  presence  of  the  innominate  artery 
explains  the  predominance  of  the  right  over  the  left  upper  extremity ;  but  this  opinion 
is  entirely  unfounded. 

The  arteria  innominata  gives  off  no  collateral  branch,  except  in  those  cases  in  which 
it  affords  origin  to  the  thyroid  artery  of  Neubauer,  so  named  from  the  anatomist  who 
called  attention  to  this  anatomical  variety.*  The  same  anatomist  has  seen  the  right  in- 
ternal mammary  artery  arise  from  the  brachio-cephahc  trunk 

The  Right  and  Left  Sub-clavian  Arteries. 

The  right  sub-clavian  artery  {g,  fig.  198  ;  f,fig.  204)  arises  from  the  innominate  (c) ; 
the  left  sub-clavian  {g"),  from  the  arch  of  the  aorta. 

Varieties  of  Origin. — One  very  common  variety  is  that  in  which  the  right  sub-clavian 
arises  below  the  left,  from  the  posterior  and  inferior  part  of  the  arch  of  the  aorta,  from 
which  it  passes  upward  and  to  the  right  side,  generally  behind  the  trachea  and  oesopha- 
gus, sometimes  between  the  two,  and  rarely  in  front  of  the  trachea,  t 

The  precise  termination  of  this  artery  is  not  well  defined.  By  some  authors  it  is  said 
to  end,  and  the  vessel  to  take  the  name  of  axillary  artery  as  it  passes  between  the  sca- 
leni.t  It  appears  to  me  more  convenient  to  take  the  clavicle  as  indicating  the  respect- 
ive limits  of  the  two  vessels.  All  above  the  clavicle,  then,  belongs  to  the  sub-clavian, 
and  all  below  it  to  the  axillary  artery.^ 

From  the  difference,  as  to  origin,  between  the  right  and  left  sub-clavians,  they  diffei 
from  each  other  remarkably  in  length,  direction,  and  relations. 

Differences  in  Length. — The  right  sub-clavian  is  shorter  than  the  left  by  the  length  of 
the  innominate  artery  ;  and  we  should,  moreover,  bear  in  mind  the  slight  difference  in 
the  height  between  the  origin  of  the  innominate  and  the  left  sub-clavian.  The  difference 
in  the  size  of  the  two  sub-clavian  arteries  requires  no  special  notice. 

Differences  in  Direction. — The  right  sub-clavian  passes  at  first  obliquely  outward  and  a 
little  upward,  and  then  bends  over  the  apex  of  the  lung,  describing  a  curve  with  the  con- 
cavity looking  downward.  The  left  sub-clavian  passes  vertically  upward  before  curving 
over  the  apex  of  the  lung,  opposite  which  it  changes  its  direction  abruptly,  and  becomes 
horizontal. 

Differences  in  Relations. — In  describing  these,  we  shall  divide  the  sub-clavian  artery 
into  three  portions  :  the^rs^,  extending  from  the  origin  of  the  artery  to  the  scaleni  mus- 
cles ;  the  second,  situated  between  the  scaleni ;  and  the  third,  extending  from  the  scale- 
ni to  the  clavicle.  The  relations  of  the  right  and  left  sub-clavians  differ  from  each  other 
only  in  the  first  of  these  portions. 

The  first  portion  {I,  fig-  204)  of  the  right  sub-clavian  is  in  relation  in  front  with  the  inner 
end  of  the  clavicle,  the  sterno-clavicular  articulation,  the  platysma,  and  the  clavicular 
attachment  of  the  sterno-mastoid  muscle,  with  the  stemo-hyoid  and  sterno-thyroid  mus- 
cles, with  the  termination  of  the  internal  jugular  and  vertebral  veins  in  the  sub-clavian 

*  This  inferior  thyroidean  artery  arises,  perhaps,  more  frequently  from  the  arch  of  the  aorta,  between  the 
brachio-cephalic  trunk  and  the  left  primitive  carotid. 

t  [It  rarely  passes  between  the  trachea  and  o;sophagTis  ;  and  it  appears  there  is  no  record  of  its  having  been 
actually  seen  in  front  of  the  trachea  (see  Quain  on  the  Arteries).'^ 

X  According  to  some  authoi-s,  the  artery  changes  its  name  as  it  emerges  from  between  the  scaleni ;  accord- 
ing to  others,  while  it  is  yet  between  those  muscles. 

^  We  are  in  the  habit  of  dividing  this  artery  into  three  portions  :  a  cardiac,  a  middle,  and  an  axillary  por- 
lion.  The  first,  that  part  between  its  origin  and  the  scaleni ;  the  second,  the  portion  embraced  between  tho 
Bcaloni ;  and  the  third,  the  remaining  part  of  the  artery. — Ed. 


THE  VERTEBRAL  ARTERY.  533 

Tein,  and  with  the  right  pneumogastric  and  phrenic  nerves  ;  behind,  with  the  recurrent 
laryngeal  nerve  and  the  transverse  process  of  the  seventh  cervical  vertebra ;  on  the  out- 
er side,  with  the  mediastinal  pleura,  which  separates  it  from  the  lung.  On  the  inner 
side,  it  is  separated  from  the  conmion  carotid  by  a  triangular  interval.*  It  is  surround- 
ed by  loose  cellular  tissue,  a  great  number  of  lymphatic  glands,  and  nervous  loops  formed 
by  the  great  sympathetic. 

The  first  portion  of  the  left  sub-clavian  is  in  relation  with  the  same  parts,  though  to  a 
somewhat  different  extent :  thus,  its  relations  with  the  left  mediastinal  pleura  and  lung 
are  much  more  extensive.  The  sub-clavian  vein  crosses  it  at  right  angles,  instead  of 
being  parallel  to  it ;  but  the  left  pneumogastric  and  phrenic  nerves  run  parallel  to,  in- 
stead of  crossing  it.  It  is  parallel  to  the  left  common  carotid,  instead  of  forming  an  an- 
gle with  it ;  and,  instead  of  being  near  the  clavicle,  the  left  sub-clavian  is  close  to  the 
vertebral  column,  and  rests  on  the  longus  colli,  the  inferior  cervical  ganglion  of  the  sym- 
pathetic nerve,  and  the  thoracic  duct,  which  is  there  to  its  inner  side. 

The  second  portion  of  both  the  right  and  left  sub-clavian  arteries,  situated  between  the 
scaleni,  is  in  close  relation  below  with  the  middle  of  the  upper  surface  of  the  first  rib,  on 
which  there  is  a  corresponding  depression  behind  the  tubercle  for  the  attachment  of  the 
anterior  scalenus ;  above,  with  the  two  scaleni,  which  are  in  contact  with  each  other 
above  the  vessel ;  behind,  with  the  brachial  plexus  ;  in  front,  with  the  scalenus  anticus, 
which  separates  the  subclavian  artery  from  the  sub-clavian  vein.  This  separation  of  the 
artery  from  the  vein  is  one  of  the  most  important  points  in  its  history.  + 

The  third  portion  of  the  sub-clavian,  or  that  extending  from  the  scaleni  to  the  clavicle, 
corresponds  to  a  triangular  space,  bounded  in  front  by  the  stemo-mastoid  and  anterior 
scalenus,  above  by  the  omo-hyoid,  and  below  by  the  clavicle  :  this  space  is  named  the 
lower  or  clavicular  portion  of  the  posterior  triangle  of  the  neck,  which  is  bounded  in  front 
by  the  stemo-mastoid,  behind  by  the  trapezius,  below  by  the  clavicle.  In  front  of,  but 
somewhat  lower  than  the  artery,  is  the  clavicle,  that  bone  being  separated  from  the  ves- 
sel by  the  sub-clavian  vein,  which  is  here  below  and  in  contact  with  the  artery,  and  by 
the  sub-clavius  muscle ;  behind  and  to  the  outside  of  the  artery  is  the  brachial  plexus 
of  nerves,  which  surrounds  the  vessel  in  the  axilla ;  it  is  covered  by  the  deep  cervical 
fascia,  the  platysma,  the  superficial  fascia,  and  the  skin,  and  is  crossed  by  the  descend- 
ing cutaneous  branches  of  the  cervical  plexus,  and  obliquely  by  the  supra-scapular  ar- 
tery and  vein ;  below,  it  rests  upon  the  first  rib. 

In  consequence  of  these  relations,  the  sub-clavian  artery  may  be  compressed,  and  the 
circulation  of  the  upper  extremity  stopped  by  forcible  depression  of  the  clavicle  ;  the 
sub-clavian  may  be  easily  felt,  compressed,  and  tied  above  the  clavicle ;  and,  lastly,  it 
follows  that  the  sharp  fragments  of  a  broken  clavicle  can  wound  the  coats  of  the  artery 
only  after  having  transfixed  the  sub-clavius  muscle  and  the  sub-clavian  vein. 

This  artery,  moreover,  presents  individual  varieties  both  in  regard  to  its  direction  and 
relations ;  it  usually  rises  slightly  above  the  clavicle,  but  in  persons  with  short  necks 
and  high  shoulders  it  is  situated  deeply  under  the  clavicle,  while  in  those  who  have  long 
necks  and  low  shoulders  it  may  even  slightly  raise  up  the  platysma  and  the  skin.  But 
the  most  important  variety  is  that  in  which  the  relations  of  the  sub-clavian  with  the  sca- 
leni muscles  are  changed.  It  is  not  uncommont  to  see  the  sub-clavian  artery  situated 
in  front  of  the  scalenus  anticus,  forming  immediate  relations  with  the  sub-clavian 
▼ein.ij 

Collateral  Branches. — The  sub-clavian  artery  gives  off  certain  collateral  branches, 
which  may  be  divided  into  the  superior,  inferior,  and  external.  The  superior  are  the  rer- 
tebral  and  the  inferior  thyroid ;  the  inferior  are  the  internal  mammary  and  the  superior  in- 
tercostal ;  the  external  are  the  supror scapular,  the  posterior  scapular  or  transversalis  colli, 
and  the  deep  cervical. 

Besides  these,  the  sub-clavian  arteries  sometimes  give  off,  near  their  origin,  pericar- 
diac, thymic,  and  oesophageal  branches ;  not  unfrequently  the  left  sub-clavian  gives  ori- 
gin to  the  bronchial  artery  of  that  side. 

The  Vertebral  Artery. 

TTie  vertebral  artery,  destined  for  the  cerebro-spinal  nervous  centre,  supplies  more 
particularly  the  spinal  cord,  the  pons  Varolii,  the  cerebellum,  and  the  posterior  portion 
of  the  cerebrum.  It  is  the  first  and  largest  branch  of  the  sub-clavian,  and  in  some 
subjects  is  about  equal  in  size  to  the  continuation  of  that  vessel.  A  very  great  inequal- 
ity in  the  size  of  the  two  vertebrals  is  rather  frequently  met  with.    Morgagni  states 

*  [It  has  been  observed  by  Professor  R.  Quain  (Joe.  cit.)  that  the  origin  of  the  right  sub-clavian  is  sometimes 
partially  or  completely  covered  by  the  right  carotid,  a  process  of  the  cervical  fascia  separating  the  two  vessels.] 

t  [Professor  Quain  has  seen,  in  a  few  cases,  the  artery  perforating  the  anterior  scalenus  ;  and  it  has  even 
been  found,  by  himself  and  others,  anterior  to  that  muscle,  and  therefore  in  contact  with  the  vein.] 
t  According  to  our  observation,  this  is  a  most  rare  variety. — Ed. 

♦  In  a  case  of  this  kind,  which  has  been  communicated  to  me  by  M.  Demeaux,  adjunct  of  anatomy  to  the 
Faculty,  there  was  no  brachio-cephalic  trunk,  but  a  bi-carotid  trunk  :  the  right  sub-clavian  arose  from  the  de- 
scending aorta,  and  went  behind  the  trachea  and  the  oesophagus.  (This  preparation  has  been  deposited  in  the 
museum  of  the  Faculty.) 


h^ 


ANGEIOLOGT 


that  he  has  seen  the  right  vertebral  four  times  as  large  as  the  left ;  I  have  seen  the  left 
vertebral  represented  by  a  very  small  twig. 

The  vertebral  artery  arises  (2,  fig.  204)  from  the  upper  and  back  part  of  the  sub-clavi- 
an,  at  the  point  where  it  curves  over  the  apex  of  the  lung ;  the  left  vertebral  often  ari- 
ses directly  from  the  arch  of  the  aorta,  between  the  common  carotid  and  sub-clavian  of 
the  same  side.  The  right  vertebral  has  been  found  arising  from  the  point  at  which  the 
innominate  divides  into  the  right  common  carotid  and  right  sub-clavian.  It  has  also 
been  seen  arising  by  two  trunks,  both  of  which  sometimes  come  from  the  sub-clavian ; 
and  at  others,  one  proceeds  from  that  artery,  and  the  other  from  the  arch  of  the  aorta.* 

Immediately  after  leaving  the  sub-clavian,  the  vertebral  artery  passes  vertically  up- 
ward and  a  little  backward,  enters  between  the  transverse  processes  of  the  sixth  and 
seventh  cervical  vertebrae,  in  order  to  reach  the  foramen  in  the  base  of  the  transverse 
process  of  the  sixth,  ascends  through  the  foramina  in  the  transverse  processes  of  the 
succeeding  cervical  vertebrae,  describing  some  slight  curves  in  passing  from  one  to  an- 
other. In  order  to  gain  the  foramen  in  the  axis,  it  forms  a  considerable  vertical  curve 
between  the  atlas  and  that  bone ;  it  then  forms  a  second  horizontal  curve  between  the 
atlas  and  the  occipital  bone.t  perforates  the  posterior  occipito-atloid  ligament  and  dura 
mater,  and  enters  the  cranium  by  the  foramen  magnum.  The  right  and  left  vertebral 
arteries  turn  round  the  sides  of  the  medulla  oblongata,  between  the  hypoglossal  and  sub- 
occipital nerves,  converge  {i  i,  fig.  208)  in  front  of  the  medulla,  and  near  the  furrow 
which  separates  it  from  the  pons  Varolii,  unite  at  an  acute  angle  to  form  the  basilar  ar- 
tery {b).  The  two  remarkable  curves  described  by  the  vertebral  artery  before  it  enters 
the  cranium  are  in  accordance  with  those  formed  by  the  internal  carotid  within  the  ca- 
rotid canal  and  cavernous  sinus.  I  have  seen  the  vertebral  very  tortuous  at  the  lower 
part  of  the  neck,  before  it  entered  the  covered  way  formed  for  it  by  the  cervical  trans- 
verse processes. 

Not  unfrequently  the  vertebral  artery  enters  the  canal  of  the  transverse  processes  at 
the  fifth  cervical  vertebra ;  it  has  occasionally  been  seen  to  enter  at  the  fourth,  third,  and 
even  at  the  second.     It  very  rarely  enters  the  foramen  of  the  seventh  cervical  vertebra. 

Relations. — Before  entering  the  foramen  of  the  sixth  cervical  vertebra,  the  vertebral 
artery  is  situated  deeply  upon  the  spine,  between  the  longus  colli  and  the  anterior  scale- 
nus, and  behind  the  inferior  thyroid  artery.  The  thoracic  duct  is  at  first  on  the  inner 
side,  and  then  in  front  of  the  left  vertebral  artery.  From  the  sixth  cervical  vertebra  to 
the  atlas,  it  is  protected  by  the  canal  formed  by  the  series  of  foramina  in  the  transverse 
processes,  and  in  the  intervals  between  them  by  the  inter-transversales  muscles ;  it  lies 
in  front  of  the  cervical  nerves,  but  the  sub-occipital  nerve  lies  between  it  and  the  groove 
in  the  atlas.  In  the  intervals  between  the  axis  and  atlas,  and  between  the  atlas  and  oc- 
cipital bone,  it  is  in  relation  with  the  complexus  and  trachelo-mastoideus,  and  with  the 
rectus  capitis  posticus  major  and  obliquus  superior.  In  those  cases  where  the  vertebral 
artery  does  not  enter  the  vertebral  foramina  until  it  has  passed  up  to  the  third  or  second 
cervical  vertebra,  it  goes  upward  along  the  side  of  the  internal  carotid  artery.  In  the 
cranium,  it  is  situated  between  the  basilar  surface  of  ti^e  occipital  bone  and  the  anterior 
surface  of  the  medulla  oblongata. 

Collateral  Branches. — In  its  course  along  the  canal  of  the  transverse  processes,  the  ver- 
tebral artery  gives  off  spinal  branches,  which  enter  the  vertebral  canal  through  the  in- 
ter-vertebral foramina,  and  are  distributed  in  the  same  manner  as  the  spinal  branches  of 
the  intercostal  and  lumbar  arteries.  Several  of  these  branches,  however,  are  derived 
from  the  ascending  cervical  artery,  and  from  the  praevertebral  branches  of  the  ascending 
pharyngeal.  From  the  two  curves  formed  by  the  vertebral  artery  arise  a  great  number 
of  small  muscular  branches,  which  are  distributed  to  the  deep  muscles  of  the  cervical  re- 
gion, and  anastomose  with  branches  of  the  occipital  and  deep  cervical  arteries.  Among 
these  there  is  one,  sometimes  two,  which  enters  the  cranium  through  the  foramen  mag- 
num, and  is  distributed  to  the  dura  mater  lining  the  inferior  occipital  fossa:,  and  to  the 
falx  cerebelli :  it  is  the  posterior  meningeal  artery  (rami  meninges  posteriores,  Holler). 
Soemmering  has  pointed  out  a  small  meningeal  branch,  which  enters  the  cranium  with 
the  first  cervical  or  sub-occipital  nerve,  and  which  appears  to  me  to  be  constant. 

In  the  cranium,  before  uniting  to  form  the  basilar,  the  vertebral  arteries  give  off  the 
posterior  and  anterior  spinal  arteries,  and  the  inferior  cerebellar. 

Spinal  Arteries. — These  are  small  branches,  remarkable  for  being  extremely  slender, 
and  for  arising  at  an  obtuse  angle,  so  that  they  descend  in  a  precisely  opposite  direction 

*  One  of  the  most  remarkable  varieties  of  origin  of  the  vertebral  artery  is  the  followring,  which  has  been 
communicated  to  me  by  Professor  Dubreuil : 

In  a  woman  of  forty- five  years,  the  left  vertebral  arteries  arose  neither  on  the  right  nor  on  the  left  side  from  the 
corresponding  sub-clavian  arteries.  The  left  Tertebral  took  its  origin  directly  from  the  arch  of  the  aorta,  be- 
tween the  left  sub-clavian  and  the  left  primitive  carotid.  The  right  vertebral  arose  from  the  right  primitive 
carotid,  at  the  distance  of  four  millimeters  from  its  origin.  Both  arteries  passed  upward,  in  parallel  lines, 
along  the  vertebral  column,  as  far  as  the  third  cervical  vertebra,  when  they  entered  the  vertebral  foramina  of 
the  transverse  processes  of  this  vertebra,  having  previously  given  off  several  small  supplementary  branches  of 
the  ascending  cervical  arteries.    The  sub-clavian  artery  gave  here  origin  only  to  five  collateral  branches. 

t  Have  the  curvatures  of  the  vertebral  artery  any  relation  to  the  motions  of  the  head  upon  the  vertebnkl 
(tolumn  ? 


THE  VERTEBRAL  ARTERY.  635 

to  the  vertebral  arteries,  which  ascend  vertically ;  they  are  distinguished  into  the  anterior 
and  the  posterior  spinal  artery.  It  is  incorrect  to  regard  them  as  continued  down  to  the 
lower  part  of  the  spinal  cord :  they  are  so  slender,  that  they  can  only  supply  a  very  small 
portion  of  the  cord ;  in  reality,  they  are  nothing  more  than  the  commencement  of  the  spi- 
nal arteries,  which  are  continued  through  the  whole  extent  of  the  cord  by  means  of 
branches  given  off  from  the  cervical,  dorsal,  and  lumbar  arteries. 

The  posterior  spinal  artery  arises  from  the  vertebral  while  that  vessel  lies  upon  the 
side  of  the  medulla  oblongata,  and  sometimes  from  the  inferior  cerebellar  artery ;  it  pass- 
es in  a  tortuous  manner  inward,  and  divides  into  an  ascending  branch,  which  terminates 
upon  the  sides  of  the  fourth  ventricle,  and  a  descending  tortuous  branch,  which  winds 
along  the  sides  of  the  posterior  surface  of  the  cord,  and  divides  into  two  twigs,  a  small 
one  situated  before,  and  a  larger  one  placed  behind  the  posterior  roots  of  the  spinal 
nerves  ;  around  each  of  these  roots  they  form  a  network,  and,  by  means  of  transverse 
branches,  which  are  twisted  on  themselves  and  much  interlaced,  they  communicate  with 
the  corresponding  branches  of  the  opposite  side.  Chaussier  was  therefore  incorrect  in 
giving  the  name  of  the  posterior  median  artery  of  the  spine  to  the  two  posterior  spinal  ar- 
teries. Tliese  small  branches  of  the  vertebral  are  soon  exhausted  ;  they  are  continued 
on  each  side  by  branches  of  the  cervical,  dorsal,  and  lumbar  spinal  arteries,  which  run 
upward  along  the  posterior  roots  of  the  nerves,  and  having  reached  the  sides  of  the  cord, 
divide  into  ascending  and  descending  branches,  which  anastomose  witli  the  neighbour- 
ing vessels,  form  a  network  around  each  pair  of  nerves,  and  communicate  by  tortuous 
transverse  branches  with  the  arteries  of  the  opposite  side. 

The  anterior  spinal  artery  (m,  Jig.  208),  which  is  somewhat  larger  than  the  posterior, 
arises  from  the  vertebral  near  the  basilar,  sometimes  even  from  the  basilar  itself,  or  from 
the  inferior  cerebellar,  passes  almost  vertically  inward  and  downward,  in  front  of  the 
medulla  oblongata,  and  anastomoses  in  the  same  manner  as  the  vertebral  with  its  fellow 
of  the  opposite  side,  so  as  to  constitute  a  median  trunk,  which  is  correctly  named  the 
anterior  median  artery  of  the  spine  ;  it  is  situated  beneath  the  pearly  fibrous  band  found 
along  the  anterior  median  furrow,  and  is  continued  by  branches  from  the  cervical,  dorsal, 
and  lumbar  arteries. 

The  anterior,  or  median  spinal  artery,  therefore,  results  from  the  anastomoses  of  the 
two  anterior  spinal  branches  of  the  vertebral.  In  one  case  there  was  no  artery  on  the 
left  side,  but  the  right  was  twice  as  large  as  usual.  The  vessel  is  of  considerable  size, 
until  it  has  passed  below  the  cervical  enlargement  of  the  cord,  from  which  point  down 
nearly  to  the  dorsal  enlargement  it  becomes  exceedingly  delicate  ;  a  little  above  the  last- 
named  enlargement  it  suddenly  increases  in  size,  again  gradually  diminishes  as  it  ap- 
proaches the  lower  end  of  the  spinal  cord,  and  becoming  capillary,  is  prolonged  down  to 
the  sacrum,  together  with  the  fibrous  string  in  which  the  spinal  cord  tenninates. 

During  its  course,  this  artery  receives  lateral  branches  from  the  ascending  cervical 
and  the  vertebral  in  the  neck,  and  from  the  spinal  branches  of  the  intercostal  and  lum- 
bar arteries  in  the  back  and  loins.  These  branches  penetrate  the  fibrous  canal  formed 
by  the  dura  mater  around  each  of  the  spinal  nerves  ;  become  applied  to  the  nervous 
ganglia,  to  which  they  supply  branches  ;  get  intermixed  with,  and  follow  the  course  of, 
the  corresponding  nerves ;  send  small  twigs  backward  to  the  posterior  spinal  arteries, 
and  terminate  in  the  anterior  spinal  trunk,  at  variable  angles,  similar  to  those  at  which 
the  nerves  are  attached  to  the  spinal  cord. 

The  re-enforcing  spinal  branches  are  not  nearly  so  numerous  as  the  nerves.  If  the  con- 
dition which  I  have  observed  in  three  subjects  be  constant,  there  are  three  in  the  cervi- 
cal region,  one  or  two  in  the  contracted  portion  of  the  cord,  and  one  only  at  the  inferior 
enlargement.  This  last,  which  in  one  case  was  as  large  as  the  ophthalmic  artery,  reach- 
ed the  cord  at  a  very  acute  angle ;  opposite  the  median  line,  it  divided  into  two  branch- 
es, one  ascending  and  very  small,  the  other  descending,  of  considerable  size,  and  form- 
ing the  true  continuation  of  the  trunk. 

From  the  anterior  spinal  arteries  there  proceed  a  great  number  of  twigs,  which  pass 
backward  into  the  anterior  median  furrow,  and  from  thence  into  the  substance  of  each 
half  of  the  corresponding  portion  of  the  cord ;  also  some  lateral  branches,  which  ramify 
on  the  sides  of  the  cord  in  the  pia  mater. 

The  Inferior  and  Posterior  Cerebellar  Arteries. — These  (A  h)  arise  from  the  outer  side  of 
the  vertebral,  and  sometimes  from  the  basilar ;  they  are  of  considerable  size,  and  often 
differ  in  this  respect  on  the  two  sides.  Each  of  them  soon  turns  round  the  medulla  ob- 
longata, pursuing  a  tortuous  course,  passes  between  the  filaments  of  origin  of  the  hypo- 
glossal nerve,  runs  in  front  of  the  roots  of  the  pneiunogastric  and  glosso-pharyngeal  nerves, 
crosses  the  restiform  body,  and  reaches  the  back  of  the  medulla  oblongata  on  one  side  of 
the  opening  of  the  fourth  ventricle  ;  it  then  passes  backward,  between  the  inferior  ver- 
miform process  and  lateral  lobe  of  the  cerebellum,  and  divides  into  two  branches  :  one 
internal,  which  continues  along  the  furrow  between  the  vermiform  process  and  lateral 
lobe,  supplies  the  former,  and  turns  upward  into  the  notch  in  the  posterior  margin  of  the 
cerebellum  ;  the  other  branch  is  external,  and  passes  outward  upon  the  lower  surface  of 
the  cerebellum,  and  divides  into  a  great  number  of  twigs,  which  may  be  traced  as  far  as 


536  ANGEIOLOGY. 

the  circumference  of  the  cerebellum,  and  which  anastomose  with  those  of  the  superior 
cerebellar  artery. 

The  Basilar  Trunk. — The  basilar  trunk  (^>)  results  from  the  junction  or  confluence  of 
the  two  vertebral  arteries.  It  is  larger  than  either  of  them  singly,  but  its  area  is  not 
equal  to  the  sum  of  their  areas ;  so  that,  by  this  arrangement,  the  passage  of  the  blood 
is  accelerated.  It  commences  opposite  the  furrow  between  the  medulla  oblongata  and 
the  pons  Varolii,  and  terminates  by  bifurcating  in  front  of  the  anterior  border  of  the  pons ; 
its  length,  therefore,  corresponds  to  the  antero-posterior  diameter  of  the  pons,  on  the 
median  furrow  of  which  it  is  situated.  When  the  vertebral  arteries  are  displaced  to- 
wards the  right  side  (a  very  common  condition),  the  basilar  trunk  passes  horizontally  or 
obliquely  to  the  left,  so  as  to  reach  the  median  furrow. 

It  gives  off  no  branch  from  its  lower  surface,  which  rests  upon  the  basilar  groove  of 
the  occipital  bone.  A  great  number  of  capillary  twigs  are  detached  from  its  upper  sur- 
face, and  enter  the  pons  Varolii.  From  its  sides  proceed  the  anterior  inferior  cerebellar 
and  the  superior  cerebellar. 

The  anterior  and  inferior  cerebellar  arteries  {I  I)  vary  much  in  size  in  different  subjects, 
and  are  rarely  equal  in  this  respect  on  the  right  and  left  sides  :  each  of  them  arises  from 
about  the  middle  of  the  basilar,  and  occasionally  from  the  vertebral  itself,  passes  out- 
ward and  backward,  sometimes  behind,  and  sometimes  in  front  of  the  sixth  nerve,  l^lns 
along  the  cms  crebelli,  passes  in  front  of  the  facial  and  auditory  nerves,  and  terminates 
upon  the  anterior  portion  of  the  hemisphere  of  the  cerebellum. 

The  superior  cerebellar  arteries  (t  t)  arise  one  from  each  side  of  the  basilar,  immedi- 
ately before  it  divides  into  its  two  terminal  branches ;  they  might,  therefore,  also  be  re- 
garded as  terminal  branches  of  that  artery,  which  would  thus  end  by  dividing  into  four 
branches.  Having  arisen  at  a  right  angle  behind  the  third,  or  motor  oculi  nerve,  each 
superior  cerebellar  artery,  accompanied  by  the  fourth  or  trochlear  nerve,  turns  round  the 
crus  cerebri  in  the  groove  between  it  and  the  pons  Varolii,  and,  having  reached  the  up- 
per surface  of  the  corresponding  crus  cerebelli,  divides  into  two  branches  :  one  external, 
which  passes  outward  on  the  upper  surface  of  the  cerebellum,  along  the  anterior  half  of 
its  circumference  ;  the  other  internal,  which  is  directed  inward  upon  the  sides  of  the  su- 
perior vermiform  process,  or  median  lobule  of  the  cerebellum,  and  then  subdivides  into 
an  antero-posterior  branch,  which  passes  from  before  backward  upon  the  sides  of  the 
vemiiform  process,  as  far  as  the  circumference  of  the  cerebellum,  upon  which  it  ramifies ; 
and  a  transverse  branch,  which  continues  the  original  course  of  the  vessel  towards  the 
median  line,  running  between  the  superior  vermiform  process  and  the  valve  of  Vieussens, 
and  being  distributed  to  both. 

The  terminal  branches  of  the  basilar  trunk  are  the  posterior  cerebral  arteries  (n  n) ;  they 
arise  at  variable  angles,  are  directed  forward  and  outward,  and  then  curve  backward,  so 
as  to  turn  round  the  crus  cerebri,  parallel  to  the  superior  cerebellar  arteries,  from  which 
they  are  separated  by  the  third  or  motor  oculi  nerve.  They  follow  the  concave  bordei 
of  tiie  great  transverse  fissure  of  the  brain,  and,  having  reached  the  posterior  extrem- 
ity of  the  corpus  callosum,  leave  this  fissure  to  pass  backward  upon  the  lower  surface 
of  the  posterior  lobe  of  the  cerebrum,  where  they  may  be  traced  as  far  as  the  occipital 
region.  Each  of  the  posterior  cerebral  arteries  gives  off,  immediately  after  its  origin,  an 
immense  number  of  small  parallel  twigs,  which  enter  the  substance  of  the  brain  between 
the  anterior  crura,  whence  the  name  of  perforated  spot  given  to  that  portion  of  the  brain. 
Just  as  each  posterior  cerebral  artery  curves  backward,  it  receives  the  communicating 
artery  of  Willis  (r),  which  is  sometimes  very  large,  and  at  other  times  very  small.  When 
large,  it  evidently  assists  in  the  formation  of  the  posterior  cerebral,  which,  after  its  junc- 
tion with  the  communicating  artery,  sometimes  becomes  doubled  or  trebled  in  size.  The 
part  performed  by  the  internal  carotid  in  the  formation  of  the  posterior  cerebral  is,  there- 
fore, subject  to  variety.  In  certain  cases,  as  I  have  already  stated,,  the  posterior  cere- 
bral is  exclusively  derived  from  it. 

The  posterior  choroid  artery  arises  from  the  back  part  of  the  posterior  cerebral,  imme- 
diately after  the  junction  of  that  vessel  with  the  communicating  artery ;  it  turns  round 
the  crus  cerebri,  passes  above  and  supplies  the  tubercula  quadrigemina,  and  terminates 
in  the  velum  interpositum  and  choroid  plexus. 

As  the  posterior  cerebral  artery  quits  the  crus  cerebri,  it  gives  off  a  branch  which 
passes  outward  and  backward,  crosses  obliquely  the  long  convolution  which  forms  the 
lateral  boundary  of  the  great  fissure  of  the  brain,  and  ramifies  upon  the  lower  surface  of 
the  cerebrum.  Lastly,  the  posterior  cerebral  gives  off  a  small  constant  branch,  which 
may  be  called  the  artery  of  the  fascia  dentata,  to  which  it  is  distributed. 

Remarks  on  the  Arteries  of  the  Brain,  Cerebellum,  and  MeduU-a  Oblongata. 

The  arteries  of  the  encephalon,  i.  e.,  of  the  brain,  cerebellum,  and  medulla,  are  deri 
ved  from  four  principal  trunks,  tw^o  anterior,  viz.,  the  internal  carotids,  which  arise  from 
the  common  carotids,  and  two  posterior,  viz.,  the  vertebrals,  which  are  branches  of  the 
sub-clavian  arteries.  There  are  several  circumstances  to  be  remarked  concerning  these 
vessels,  viz.,  their  great  size,  which  is  dependant  on  that  of  the  brain  ;  their  depth  from 


THE  INFERIOR  THYROID  ARTERY.  637 

the  surface  before  they  enter  the  cranium ;  the  numerous  curves  formed  by  them  as  they 
are  entering  the  cranial  cavity,  the  use  of  vphich  is  evidently  to  retard  the  course  of  the 
blood  ;  the  absence  of  any  large  collateral  branches,  the  only  exception  being  the  oph- 
thalmic branch  of  the  internal  carotid,  by  the  existence  of  which  the  circulation  in  the 
eye  is  connected  with  that  in  the  brain.  Another  remarkable  point  concerning  these 
vessels  is  their  anastomoses  at  the  base  of  the  cranium,  viz.,  the  anastomosis,  or,  rath- 
er, the  confluence  of  the  right  and  left  vertebral  so  as  to  form  the  basilar  artery ;  the 
anastomosis  of  the  right  and  left  internal  carotids  by  means  of  the  anterior  communica- 
ting artery,  which  unites  the  anterior  cerebrals,  and  the  anastomosis  of  the  internal  ca- 
rotids with  the  vertebrals  by  the  communicating  arteries  of  Willis.  By  these  anasto- 
moses an  arterial  hexagon  (the  circle  of  Willis)  is  formed,  the  anterior  margins  of  which 
correspond  with  the  anterior  cerebral  arteries,  the  posterior  with  the  posterior  cerebrals,  ' 
and  the  lateral  with  the  communicating  arteries  of  Willis.* 

From  this  hexagon,  as  from  a  centre,  proceed  all  the  arteries  of  the  brain,  viz.,  from 
the  anterior  angle,  the  anterior  cerebral  arteries  ;  from  the  posterior  angle,  the  basilar 
artery  ;  from  the  anterior  lateral  angle  on  each  side,  the  middle  cerebral ;  and  from  the 
posterior  lateral  angle  on  each  side,  the  posterior  cerebral  artery 

Owing  to  the  existence  of  these  large  anastomotic  communications,  any  one  of  the 
four  arterial  trunks  would  be  sufficient  to  carry  on  the  circulation  in  the  brain,  if  the 
other  three  were  wanting  or  obliterated  The  situation  of  this  arterial  hexagon  between 
the  bones  of  the  cranium  and  the  brain  is  remarkable,  because  it  explains  the  alternate 
movements  of  elevation  and  depression  seen  in  the  brain  when  that  organ  is  exposed 
during  life 

It  should  also  be  observed,  that  the  arteries  of  the  cerebellum,  pons  Varolii,  and  me- 
dulla oblongata,  are  derived  from  the  same  sources  as  those  of  the  brain. 

Lastly,  as  to  the  mode  of  distribution  of  these  vessels,  it  may  be  remarked,  that  the 
arteries  of  the  brain  pass  over  the  free  surface  of  one  or  more  convolutions,  dip  into  the 
sulci  between  the  convolutions,  are  reflected  from  one  side  of  them  to  the  other,  give 
off  a  great  number  of  very  small  branches,  emerge  from  a  given  sulcus  to  regain  the 
surface  of  the  adjacent  convolutions,  and  so  on  until  they  are  exhausted.  The  princi- 
pal arteries  of  the  cerebellum  run  upon  its  surface  without  passing  into  the  sulci,  be- 
tween the  laminae,  into  which  they  send  only  very  small  branches.  With  some  excep- 
tions, the  arteries  are  reduced  to  capillary  dimensions  before  they  enter  the  nervous 
substance. 

The  Inferior  Thyroid  Artery. 

Dissection. — Dissect  the  muscles  of  the  sub-hyoid  region ;  follow  the  branches  of  the 
thyroid  ;  trace  the  divisions  of  the  ascending  cervical  artery  into  the  grooves  upon  the 
transverse  processes  of  the  cervical  vertebrae,  and  into  the  vertebral  canal. 

The  inferior  thyroid  artery.  (3,  fig.  204)  arises  from  the  front  of  the  sub-clavian  on  a 
plane  anterior  to  the  vertebral,  which  often  comes  off  exactly  opposite  to  it.  It  varies 
remarkably  in  size  and  origin,  as  well  as  in  the  branches  which  it  furnishes.  It  fre- 
quently arises  from  the  common  carotid ;  sometimes  from  the  arch  of  the  aorta,  between 
the  brachio-cephalic  and  the  left  common  carotid ;  at  other  times  from  the  brachio-ce 
phalic  itself     Lastly,  it  is  occasionally  replaced  by  the  thyroid  of  Neubauer. 

It  often  commences  by  a  common  trunk  with  the  supra-scapular,  less  frequently  with 
the  posterior  scapular,  and  rarely  with  the  internal  mammary. 

Its  size  bears  an  inverse  proportion  to  that  of  the  superior  thyroid  of  the  same  side 
and  depends,  also,  on  the  presence  or  absence  of  a  third  thyroid.  It  is  larger  in  infancy 
than  at  any  other  period.  In  certain  cases  of  goitre  it  becomes  prodigiously  developed. 
Sometimes  there  is  merely  a  trace  of  its  existence,  or  it  is  even  altogether  wanting. 

Immediately  after  its  origin  it  passes  vertically  upward,  then  descends  so  as  to  de- 
scribe a  curve  with  its  concavity  directed  downward,  and  again  forms  another  curve 
with  its  concavity  turned  upward,  to  reach  the  lower  end  of  the  lateral  lobe  of  the  thy 
roid  gland,  in  the  interior  of  which  it  ramifies. 

Relations. — Behind,  it  is  in  relation  with  the  trachea,  the  oesophagus,  and  the  verte- 
bral column,  being  separated  from  the  latter  by  the  praevertebral  muscles  and  the  ver- 
tebral artery.  Its  relation  with  the  oesophagus  is  more  marked  on  the  left  than  on  the 
right  side,  and  it  is  important  to  bear  this  fact  in  mind  in  performing  thq  operation  of 
oesophogotomy.  In  front,  its  first  curve  embraces  the  common  carotid,  the  internal 
jugular  vein,  the  pneiuntiogeistric,  and  the  great  sympathetic  nerves.  The  middle  cervi- 
cal ganglion,  when  it  exists,  rests  upon  it.  The  second  curve  embraces  the  recurrent 
laryngeal  nerve,  and  is  also  in  relation  with  the  muscles  of  the  sub-hyoid  region.  It 
may  be  remarked,  that  there  is  one  point  in  the  neck  where  three  arteries  come  into 
contact,  viz.,  the  common  carotid,  the  inferior  thyroid,  and  the  vertebral. 

Collateral  Branches. — The  inferior  thyroid  gives  off,  downward,  an  oesophageal  branch, 

"  In  a  person  who  died  ol  apoplexy,  Morgagni  found  a  want  of  communication  between  the  vertebrals  and 
carotids  ;  and  he  attributed  the  apoplexy  partly  to  this  circumstance,  and  partly  to  the  fact  that  the  left  ver- 
tebral arose  directly  from  the  arcli  of  the  aorta. 

Yyy 


^4|P  ANGEIOLO&Y. 

some  tracheal  branches,  and  a  small  brojichial  twig.  I  have  seen  the  right  bronchial  ar- 
tery derived  from  it.  It  also  gives  off  several  muscular  branches  to  the  scalenus  anti- 
cus  and  the  praevertebral  muscles.  The  most  remarkable  of  all  these  is  the  ascending 
cervical  artery  (4),  which  is  of  variable  size,  and  is  sometimes  so  large  that  it  may  be 
regarded  as  resulting  from  the  bifurcation  of  the  inferior  thyroid.  It  passes  vertically 
upward,  in  front  of  the  scalenus  anticus,  then  in  the  groove  between  it  and  the  rectus 
capitis  anticus  major,  to  both  of  which,  as  well  as  to  the  attachments  of  the  levator  an- 
guli  scapulae,  it  gives  some  small  branches.  The  most  remarkable  of  its  branches,  call- 
ed the  cervicorspitial,  enter  the  grooves  by  which  the  cervical  nerves  emerge,  run  in 
front  of  these  nerves,  and  anastomose  with  the  branches  of  the  vertebral  artery.  I  have 
seen  these  branches  divide  into  two  ramusculi :  the  one  anterior,  very  small,  which 
passed  in  front  of  the  vertebral  artery,  and  emerged  upon  the  sides  of  the  body  of  the 
vertebra  ;  the  other  posterior,  which  passed  between  the  corresponding  nerve  and  the 
artery,  entered  the  spinal  canal  through  the  intervertebral  foramen,  and  was  distributed 
to  the  vertebrae,  and  to  the  spinal  cord  and  its  membranes,  in  the  same  manner  as  the 
dorsal  and  lumbar  spinal  arteries.  The  praevertebral  branch  of  the  ascending  pharyn- 
geal artery  sometimes  supphes  the  cervico-spinal  branch  of  the  first  two  intervertebrcd 
spaces  in  the  cervical  region. 

Terminal  Branches. — Opposite  the  lower  extremity  of  the  lateral  lobe  of  the  thyroid 
gland,  the  inferior  thyroid  artery  divides  into  three  branches  :  of  these,  one  follows  the 
lower  border  of  the  gland,  another  passes  to  the  posterior  surface  of  its  lateral  lobe, 
while  the  third  dips  between  the  gland  and  the  trachea,  runs  along  the  lower  border  of 
the  cricoid  cartilage,  sometimes  becomes  superficial  opposite  the  isthmus  of  the  thyroid 
body,  and  forms  an  anastomotic  arch  with  its  feUow  of  the  opposite  side,  along  the  upper 
margin  of  that  isthmus. 

The  Supra-scapular  Artery. 

The  superior  or  supra-scapular  artery  {transversus  humeri,  5,  fig.  204),  destined  for  the 
supra-  and  infra-spinous  fossae,  and  which  might  also  be  denominated  the  cleido-supra- 
scapular  from  its  course,  arises  from  the  front  of  the  sub-clavian  below  the  inferior  thy- 
roid, and  often  by  a  common  tmnk,  either  with  the  posterior  scapular,  or  with  the  in- 
ferior thyroid  and  posterior  scapular  united,  forming  what  is  then  called  the  thyroid  axis. 
It  is  at  first  directed  vertically  downward,  then  bends  horizontally  outward,  to  run  along 
behind  the  clavicle  and  gain  the  upper  border  of  the  scapula,  where  it  passes  over,  very 
rarely  under,  the  ligament,  which  converts  the  coracoid  or  supra-scapular  notch  into  a 
foramen,  and,  being  reflected  over  that  ligament,  dips  into  the  supra-spinous  fossa,  and 
crossing  the  concave  border  of  the  spine  of  the  scapula,  enters  the  infra-spinous  fossa, 
in  which  situation  it  terminates  {5',  fig.  209). 

Relations. — It  is  concealed  at  its  origin  by  the  stemo-mastoid  muscle,  and  is  then  sit- 
uated along  the  base  of  the  supra-clavicular  triangle  ;  it  is  in  relation  in  front  with  the 
clavicle,  following  the  direction  of  that  bone ;  behind,  with  the  sub-clavian  artery  and 
the  brachial  plexus  of  nerves,  which  it  crosses  at  right  angles  ;  above,  with  the  deep 
fascia  and  the  platysma  myoides,  which  separate  it  from  the  skin  ;  and  below,  with  the 
sub-clavian  vein :  more  externally,  it  dips  under  the  trapezius,  and  comes  in  contact 
with  the  supra-scapular  nerve,  is  separated  from  it  at  the  coracoid  notch,  and  again  be- 
comes applied  to  it  in  the  supra-  and  infra-spinous  fossae,  where  it  is  situated  between 
the  muscles  of  the  bone. 

Collateral  Branches. — Among  a  great  number  of  unnamed  muscular  and  cutaneous 
branches,  I  would  particularly  notice,  1.  A  small  thoracic  branch,  which  passes  verti- 
cally downward  behind  the  clavicle,  perforates  the  sub-clavius,  and  anastomoses  with 
the  thoracic  arteries.  2.  A  branch  for  the  trapezius,  which  is  so  large  that  it  appears  to 
result  from  the  bifurcation  of  the  artery.  It  generally  arises  at  the  point  where  the  ves- 
sel dips  into  the  supra-spinous  fossa ;  at  other  times  it  comes  off  very  near  the  origin  of 
the  artery,  passes  from  before  backward,  turns  round  the  scaleni  muscles  parallel  with 
the  posterior  scapular  artery,  with  which  one  might  confound  it,  and  ramifies  in  the  tra- 
pezius and  the  supra-spinatus  muscles,  entering  the  former  at  its  under,  and  the  latter  at 
its  upper  surface :  some  of  the  branches  are  distributed  to  the  periosteum  of  the  acromion 
and  to  the  corresponding  integuments. 

Again,  in  the  supra-  and  infra-spinous  fossae  it  gives  off  a  great  number  of  periosteal, 
osseous,  muscular,  and  articular  branches.  In  the  infra-spinous  fossa  (5,  fig.  209),  it 
forms  a  free  arched  anastomosis  with  the  sub-scapular  artery,  and  gives  off  a  branch 
which  runs  along  the  axillary  border  of  the  scapula,  and  anastomoses  with  the  posterior 
scapular  artery  at  the  lower  angle  of  that  bone. 

The  Posterior  Scapular  Artery. 

The  posterior  scapular  {transversus  cervicis,  transvcrsalis  colli,  6,  fig.  204,  209)  is  larger 
than  the  preceding,  and  extends  from  the  sub-clavian  to  the  vertebral  border  of  the  scap- 
ula ;  it  arises  from  the  front  of  the  sub-clavian,  sometimes  to  the  inner  side  of  the  sea- 


THE    INTERNAL   MAMMARY    ARTERY.  639 

leni,  sometimes  between  them,  but  most  commonly  on  the  outer  side  of  those  muscles  ;* 
in  the  first  case  it  often  comes  off  by  a  common  trunk  with  the  inferior  thyroid,  and  in 
the  two  other  cases  by  a  common  trunk  with  the  supra-scapular.  It  passes  transversely 
and  in  a  slightly  tortuous  manner  outward,  through  the  nerves  of  the  brachial  plexus, 
and  sometimes  through  the  scalenus  posticus,  and  curves  backward  towards  the  poste- 
rior superior  angle  of  the  scapula.  Then,  opposite  the  levator  anguli  scapulae,  it  divides 
into  an  ascending  and  a  descending-  branch.  The  ascending  or  cervical  branch,  the  super- 
Jicial  cervical  artery  of  authors,  passes  beneath  the  trapezius,  and  divides  into  a  great 
number  of  twigs,  which  ramify  in  that  muscle,  in  the  levator  anguli  scapulae,  and  in  the 
splenius.  The  descending  branch  forms  the  posterior  scapular  artery,  properly  so  called 
(a.  Jig.  209),  and  may  be  regarded  as  the  continuation  of  the  vessel ;  it  turns  round  the 
posterior  superior  angle  of  the  scapula,  beneath  the  levator  Fig.  209. 

anguli,. passes  vertically  downward  along  the  vertebral  bor-  ^ 

der  of  that  bone,  and  terminates  at  the  inferior  angle  by  an-  ,  ^\ 
astomosing  with  the  sub-scapular  artery,  a  branch  of  the  ax-  ,  ^A 
illary,  and  with  the  supra-scapular,  already  described.  '^^^jS^^»— ^.^^ 

Relations. — It  is  superficial  in  the  first  part  of  its  course,         ••',:^^^^^^~^^^ 
during  which  it  traverses  the  supra-clavicular  triangle  hor-        -V>^^^^^^^ 
izontally,  being  merely  covered  by  the  cervical  fascia,  the        '^^^^ib^W^tk 
platysma  myoides,  and  the  omo-hyoid  ;  and  hence,  doubt-      ^^^-■C/Wt^^^>\ 
less,  the  name  superficial  cervical,  which  has  been  given  to       -' v~T^^^^^^\ 
it  by  some  authors.  +     It  is  but  rarely  that  the  posterior        ' /-^•^^'P^^^^^w 
scapular  turns  round  the  posterior  scalenus  and  the  brach-      , '  /  -s5^y^;J^W^w//^ 
ial  plexus,  without  passing  between  the  nerves  of  the  plex-       .^j!^yj/^  fms^mWli^w 
us,  which  it  traverses  at  variable  heights.     As  it  proceeds        \ '  v^     it0^i^MJMj]r' 
backward,  it  is  protected  by  the  trapezius ;  and,  lastly,         ^-  it'^^^^^^^oi-.JssJ 

along  the  vertebral  border  of  the  scapula,  it  lies  between  the  rhomboideus  and  the  serra- 
tus  magnus 

Its  collateral  branches  are  destined  for  the  following  muscles  :  the  trapezius,  sc£ilenus 
posticus,  levator  anguU  scapulae,  splenius,  supra-  and  infra-spinati,  sub-scapularis,  rhom- 
boideus, and  serratus  magnus. 

The  Internal  Mammary  Artery. 

The  internal  mammary,  or  internal  thoracic  artery,  not  so  remarkable  for  its  size, 
which  is  less  than  that  of  the  vertebral,  as  for  its  length  and  the  number  of  its  branches, 
arises  (7,  fig.  204)  from  the  sub-clavian  opposite  the  inferior  thyroid,  and  behind  the  supra- 
scapular. Few  arteries  are  less  variable  in  their  origin.  The  only  varieties  which  have 
been  observed  are  those  in  which  it  arises  from  the  brachio-cephalic,  from  the  arch  of 
the  aorta,  or  from  a  common  trunk  with  the  inferior  thyroid.  Immediately  after  its  ori- 
gin, it  passes  vertically  doAvnward  behind  the  inner  end  of  the  clavicle,  enters  the  thorax, 
crosses  obliquely  behind  the  cartilage  of  the  first  rib,  and  bends  a  little  inward  to  run 
along  the  first  portion  of  the  sternum,  below  which  it  resumes  its  vertical  direction,  par- 
allel to  the  border  of  that  bone,  as  low  down  as  the  sixth  rib,  where  it  divides  into  an 
internal  and  an  external  branch. 

Relations. — It  is  situated  in  front  of  the  scalenus  anticus,  and  is  covered  at  its  origin 
by  the  phrenic  nerve,  which  crosses  it  very  obliquely,  in  order  to  reach  its  inner  side  ;  it 
corresponds  to  the  inner  end  of  the  clavicle,  from  which  it  ie  separated  by  the  brachio- 
cephalic vein ;  it  is  then  placed  behind  the  costal  cartilages  and  the  intercostal  muscles, 
in  front  of  the  pleura,  from  which  it  is  separated  by  the  triangularis  sterni.  It  is  situa- 
ted about  two  lines  to  the  outer  side  of  the  margin  of  the  sternum,  so  that  a  cutting  in- 
strument may  be  carried  into  the  thorax  along  that  bone  without  injuring  the  internal 
mammary  ;  the  name  sub-sternal  is,  therefore,  not  at  all  appUcable  to  this  artery,  which 
would  be  better  named  sub-chondro-costal. 

Collateral  Branches. — These  are  very  numerous  ;  they  may  be  divided  into  the  poste- 
rior, anterior,  and  external.  The  posterior  branches  are,  the  thymic  or  anterior  mediastinals, 
and,  lower  down,  the  superior  phrenic,  an  extremely  small  artery,  which  runs  along  the 
phrenic  nerve,  is  situated,  like  it,  between  the  pericardium  and  the  corresponding  layer 
of  the  mediastinum,  and  reaches  and  is  ramified  in  the  diaphragm.  Bichat  has  seen  the 
superior  phrenic  artery  as  large  as  the  internal  mammary  itself. 

The  external  branches  are  the  anterior  intercostals.  Their  number  corresponds  with 
that  of  the  intercostal  spaces  :  they  are  small  in  the  first  two,  and  gradually  increase  or 
diminish  according  to  the  length  of  the  corresponding  spaces.  I  have  seen  the  common 
trunk  for  the  third  intercostal  space  so  large,  that  it  appeared  like  a  bifurcation  of  the 
mammary.  There  are  generally  two  branches  for  each  intercostal  space  :  one,  which 
runs  along  the  lower  margin  of  the  rib  above,  and  the  other  along  the  upper  margin  of 
the  rib  below.     These  two  branches  sometimes  arise  separately  from  the  mammary, 

*  In  the  last  case,  those  authors  who  describe  the  sub-clavian  as  terminating  between  the  scaleni,  say  that 
the  posterior  scapular  arises  from  the  axillary  artery, 
t  [It  is  the  ascending-  or  cervical  branch  only  that  is  named  superficial  cervical.] 


540  ANGEIOLOGY. 

sometimes  by  a  common  trunk ;  as  they  arise  above  the  level  of  the  space  for  which 
they  are  intended,  it  follows  that  they  pass  obliquely  behind  the  costal  cartilages.  The 
anterior  intercostals  inosculate  with  the  aortic  or  posterior  intercostals,  so  that  it  is 
sometimes  impossible  to  determine  the  limits  between  these  two  sets  of  vessels.  In 
some  subjects  they  form  a  communicating  arch  of  uniform  caliber,  extending  between 
the  internal  mammary  and  the  thoracic  aorta. 

The  anterior  branches  are  superficial,  and  correspond  in  number  to  the  intercostal  spa- 
ces ;  they  arise  from  the  internal  mammary,  pass  directly  from  behind  forward,  through 
the  corresponding  intercostal  space,  and  divide  into  cutaneous  and  muscular  branches, 
both  of  which  sets  curve  outward,  the  muscular  branches  beneath  the  pectoralis  major, 
in  which  they  ramify,  and  the  cutaneous  branches  beneath  the  skin.  Tlie  anterior 
branches  of  the  first  three  spaces  are  distributed  to  the  mammary  gland.  In  females  re- 
cently delivered,  and  in  nurses,  these  branches  become  extremely  large,  especially  the 
second,  which  I  have  seen  as  large  as  the  radial  artery,  and  very  tortuous.  Before  per- 
forating the  intercostal  muscles,  the  anterior  branches  send  some  periosteal  twigs  be- 
hind the  sternum,  some  of  which  penetrate  the  bone  directly,  while  others  ramify  on 
the  periosteum. 

Terminal  Branches. — Of  the  two  terminal  branches,  the  internal,  and  smaller,  contin- 
ues the  original  course  of  the  artery,  passes  behind  the  rectus  abdominis  muscle,  enters 
its  sheath,  and  then  divides  into  a  great  number  of  branches  ;  some  of  these  are  lost  in 
this  muscle  by  anastomosing  with  the  capillary  divisions  of  the  epigastric,  while  the  oth- 
ers emerge  from  the  sheath  of  the  rectus  by  special  openings,  and  are  distributed  to  the 
broad  muscles  of  the  abdomen,  and  to  the  integuments.  Before  leaving  the  cartilage  of 
the  seventh  rib,  it  gives  off  a  small  twig,  which  passes  inward  upon  the  side  of  the  en- 
siform  cartilage,  and  forms  an  anastomotic  arch  with  its  fellow  of  the  opposite  side,  in 
front  of  that  cartilage.  The  anastomosis  of  this  artery  with  the  epigastric,  which  has 
been  known  from  the  very  earliest  periods,  and  afforded  the  ancients  an  explanation  of 
the  intimate  physiological  connexions  between  the  genital  organs  and  mammary  glands, 
is  accomplished  in  the  usual  manner  of  capillary  communication. 

The  external  terminal  branch,  as  far  as  distribution  is  concerned,  is  the  continuation  of 
the  internal  mammary.  It  is  directed  downward  and  outward,  behind  the  cartilages  of 
the  seventh,  eighth,  ninth,  tenth,  and  eleventh  ribs,  which  it  crosses  obhquely,  and  ter- 
minates opposite  the  last  intercostal  space.  During  its  course,  it  gives  off  the  anterior 
intercostals  of  the  corresponding  spaces,  two  for  each  space,  sometimes  only  one,  which 
immediately  subdivides.  These  intercostals  diminish  gradually  in  size  as  the  spaces 
decrease  in  length,  and  are  distributed  precisely  as  the  anterior  intercostal  branches  of 
the  internal  mammary  itself  The  external  terminal  branch,  and  also  the  internal,  while 
passing  through  the  diaphragm  near  its  costal  attachments,  give  off  a  great  number  of 
branches  to  that  muscle,  and  hence  the  name  musculo-phrenic,  given  by  Haller  to  the 
external  division,  which,  indeed,  furnishes  many  more  branches  to  the  diaphragm  than 
the  internal. 

The  Deep  Cervical  Artery. 

Dissection. — Seek  at  first  for  the  artery  behind  the  scalenus  anticus,  between  the 
transverse  process  of  the  seventh  cervical  vertebra  and  the  first  rib ;  trace  it,  both  to  its 
termination,  between  the  complexus  and  semi-spinalis  colli,  and  towards  its  origin,  with- 
in the  scaleni. 

The  posterior,  or  deep  cervical,  comes  off  deeply  from  the  upper  and  back  part  of  the 
sub-clavian,  on  the  same  plane  as  the  vertebral,  to  the  outside  of  which  it  is  situated. 
Very  often  it  arises  by  a  common  trunk  with  the  first  intercostal.  It  passes  at  first  up- 
ward and  backward,  then  bends  outward  behind  the  scalenus  anticus  to  dip  between  the 
transverse  process  of  the  seventh  cervical  vertebra  and  the  first  rib.  I  have  never  seen 
it  pass  between  the  transverse  processes  of  the  sixth  and  seventh  cervical  vertebrae, 
though  for  this  purpose  I  have  examined  forty  subjects.* 

After  leaving  the  inter-transverse  space,  the  deep  cervical  artery  divides  into  two 
branches :  one  descending,  which  I  have  been  able  to  trace  as  far  as  the  middle  of  the 
dorsal  region,  between  the  long  muscles  of  the  back  ;  the  other  ascending,  which  passes 
up  between  the  complexus  and  the  semi-spinalis  colli,  in  which  it  terminates,  and  anas- 
tomoses with  the  occipital  and  vertebral  arteries. 

The  Superior  Intercostal  Arteries. 
Dissection. — This  artery  can  only  be  dissected  from  the  internal  surface  of  the  thorax. 
For  this  purpose  it  is  necessary  to  saw  through  the  thorax  vertically.    The  artery  must 
be  exposed  by  removing  the  pleura  from  the  two  upper  ribs  and  intercostal  muscles. 

*  This  relation  is  so  constant,  that,  even  in  cases  where  there  is  a  supernumerary  cervical  rib,  the  deep 
cervical  artery  passes  betwreen  this  supernumerary  rib  and  the  first  dorsal  rib.  Some  students  having  called 
me  to  examine  a  subject  in  which  this  artery  was  wanting,  I  sought  in  vain  for  it  between  the  first  rib  and 
the  transverse  process  of  the  last  cervical  vertebra,  and  then  perceived  that  there  was  a  cervical  rib,  between 
which  and  the  first  dorsal  rib  the  artery  was  found. 

[In  264  observations,  Professor  Quain  met  with  this  variety  in  the  course  of  the  artery  four  times,  and  also 
other  peculiarities.] 


THE    AXILLABY    ARTERY. 


The  superior  intercostal  artery,  intended  for  the  two  or  three  superior  intercostal  spa- 
ces, sometimes  only  for  the  first,  varies  in  size  according  to  the  extent  of  its  distribu- 
tion. It  comes  off  from  the  lower  and  back  part  of  the  sub-clavian,  near  the  deep  cer- 
vical, and  sometimes  by  a  common  trunK  with  it.  It  descends,  m  a  tortuous  manner,  m 
front  of  the  neck  of  the  first,  and  then  of  t'ne  second  rib,  on  the  outside  of  the  first  dorsal 
ganglion  of  the  sympathetic  nerve,  and  terminates  in  the  second  intercostal  space,  like 
an  aortic  intercostal  artery ;  sometimes  it  anastomoses  freely  with  the  first  of  the  aortic 
intercostals.  It  gives  off  in  each  space  a  dorso-spirud  branch,  and  an  intercostal  branch, 
properly  so  called.  It  is  not  rare  to  find  the  intercostal  branch  wanting  in  the  first  space  : 
in  all  cases  it  is  extremely  small. 

The  Axillaky  Artery. 

Dissection. — In  order  to  prepare  the  axillary,  as  well  as  all  the  other  arteries  of  the 
upper  extremity,  it  is  sufficient  to  dissect  the  muscles 
carefully,  at  the  same  time  preserving  aU  the  branches 
which  are  met  with,  and  tracing  them  to  their  origin. 

The  axillary  artery  {a  a',  fig.  210)  is  that  part  of  the 
artery  of  the  upper  extremity  which  intervenes  be- 
tween the  sub-clavian  and  the  brachial.  Its  limits, 
which  are  entirely  artificial,  are  the  clavicle,*  on  the 
onp  hand,  and  the  lower  border  of  the  pectoralis  major 
on  the  other.  It  traverses  the  axilla  diagonally,  and 
bends  opposite  the  neck  of  the  humerus,  so  as  to  be- 
come continuous  with  the  brachial  artery.  Its  upper 
part  rests  upon  the  thorax,  and  its  lower  upon  the  hu- 
merus ;  it  is  not  very  tortuous,  so  that  in  forcible  ab- 
duction of  the  arm  it  may  be  stretched  even  to  lacera- 
tion. Its  direction  corresponds  pretty  nearly  with  the 
cellular  interval  so  generally  existing  between  the 
sternal  and  the  clavicular  portions  of  the  pectoralis 
major,  or,  rather,  with  an  imaginary  line,  extending 
from  the  junction  of  the  outer  with  the  two  inner  thirds 
of  the  clavicle  to  the  inner  side  of  the  neck  of  the  hu- 
merus. 

Relations. — From  the  importance  necessarily  attach- 
ed to  an  accurate  knowledge  of  the  relations  of  this  ar- 
tery, we  shall  consider  them  in  the  four  aspects  of  the 
vessel. 

In  front,  the  axillary  artery  is  in  relation  from  above 
downward  with  the  sub-clavius  muscle,  a  process  of 
the  deep  cervical  fascia  intervening  between  them ; 
then  with  the  costo-coracoid  ligament  and  the  pecto- 
ralis major ;  next  with  the  pectoralis  minor ;  below 
this  muscle,  with  the  pectoralis  major  again  ;  and,  last- 
ly, with  the  coraco-brachialis.  In  a  subject  where  the 
pectoralis  major  had  no  clavicular  insertions,  that  por- 
tion of  the  axillary  artery  which  is  intermediate  be- 
tween the  clavicle  and  the  superior  border  of  the  pec- 
toralis minor,  was  separated  from  the  skin  only  by  the 
platysma  myoides.  Behind,  it  is  in  relation  with  the 
cellular  interval  between  the  sub-scapularis  and  serra- 
tus  magnus  ;  lower  down,  with  the  teres  major  and 
latissimus  dorsi.  On  the  inside,  it  rests  at  first  upon 
the  first  rib  and  the  first  intercostal  space ;  it  next 
leaves  the  thorax,  from  which  it  is  separated  by  the 
hollow  of  the  armpit,  and  its  inner  side  is  then  in  re- 
lation with  the  skin  which  forms  the  outer  wall  of  the 
armpit,  and  with  the  subjacent  fascia.  On  the  outside, 
it  is  at  first  embraced  by  the  concave  surface  of  the 
coracoid  process,  and  it  is  then  placed  opposite  the  head  of  the  humerus,  from  which  it 
is  separated  by  the  sub-scapularis  muscle 

Relations  with  the  Axillary  Vein  and  Nerves. — Immediately  below  the  clavicle,  tne  axdlary 
vein  is  situated  on  the  inner  side  of,  and  at  some  distance  from,  the  artery ;  lower  down, 
the  vein  lies  upon  the  artery.     The  cephahc  and  acromial  veins  pass  in  front  of  the  artery. 

Immediately  below  the  clavicle,  the  entire  brachial  plexus  is  situated  on  the  outer  side 

*  Those  authors  who  consider  the  sub-clavian  as  terminating  between  the  scaleni,  describe  the  axillary  aa 
commencing  at  the  same  point 

[The  axillary  artery  is  commonly  said,  in  this  country,  to  commence  at  the  lower  border  of  the  first  rib  (a), 
and  to  terminate  at  the  lower  border  of  the  conjoined  tendons  (a')  of  the  latissimus  dorsi  and  teres  major 
muscles.] 


542  '  ^        ANGEIOLOGY. 

of  the  artery,  only  one  thoracic  nerve  crossing  in  front  of  it.  Under  the  pectoralis  minor 
the  artery  is  surrounded  by  the  plexus  ;  it  is  at  first  embraced  by  the  external  and  inter- 
nal roots  of  the  median  nerve,  which  meet  in  the  form  of  a  V  opening  upward  ;  lower 
down,  it  is  placed  between  the  external  cutaneous  nerve  on  the  outer  side,  the  median 
in  front,  the  internal  cutaneous  and  the  ulnar  on  its  inner  side,  and  the  radial,  or  muscu- 
lo-spiral,  and  the  circumflex  behind.  In  order  to  expose  the  artery  in  the  axilla,  the  ves- 
sel may  be  sought  for  between  the  median  and  ulnar  nerves. 

In  consequence  of  these  relations,  wounds  of  the  axilla  may  be  very  serious ;  com- 
pression may  be  applied  to  the  axillary  artery,  either  by  forcibly  depressing  the  clavicle 
against  the  first  intercostal  space  and  second  rib,  or  by  placing  the  finger  upon  the  ves- 
sel in  the  axilla,  and  pressing  it  against  the  head  of  the  humerus  ;  a  ligature  may  be  ap- 
plied to  this  artery,  either  under  the  clavicle  above  the  pectoralis  minor,  or  in  the  axilla ; 
lastly,  the  artery  may  be  torn  from  extreme  violence  in  attempting  to  reduce  a  dislocation.* 

Collateral  Branches. — The  axillary  gives  off  five  branches,  viz.,  the  acromio-thoracic, 
alpove  the  pectoralis  minor ;  the  inferior  thoracic,  or  external  mammary,  below  the  pecto- 
ralis minor ;  the  inferior  scapular,  and  the  anterior  and  posterior  circumflex  arteries,  op- 
posite the  neck  of  the  humerus. 

The  Acromial  and  Superior  Thoracic  Arteries. 

Under  the  name  of  acromio-thoracic  I  include  two  arteries,  the  acromial  and  the  supe- 
rior thoracic,  which  almost  always  arise  by  a  common  trunk,  which  is  detached  at  right 
angles  from  the  inner  side  of  the  axillary  artery  immediately  above  the  pectoralis  minor, 
then  crosses  the  upper  border  of  that  muscle  at  right  angles,  and  immediately  divides 
into  the  two  above-named  branches. 

The  thoracic  branch  passes  downward  and  inward,  and  subdivides  {b  b)  between  the  two 
pectoral  muscles,  both  of  which  it  supplies,  but  especially  the  lesser.  Some  branches 
perforate  the  pectoralis  major,  and  are  distributed  to  the  skin  and  the  mamma. 

The  acromial  branch  subdivides  into  two  others :  a  descending  or  deltoid  branch  (c), 
which  enters  the  cellular  interval  between  the  pectoralis  major  and  the  deltoid,  traverses 
it  throughout,  and  is  distributed  to  these  two  muscles,  but  especially  to  the  deltoid ;  it 
is  accompanied  by  the  cephalic  vein  :  the  second  is  a  transverse  or  acromial  branch  {d), 
which  runs  horizontally  outward,  passes  over  the  apex,  and  sometimes  over  the  base  of 
the  coracoid  process,  then  upon  the  coraco-acromial  ligament,  and  runs  along  the  outer 
third  of  the  anterior  border  of  the  clavicle.  It  is  covered  in  the  whole  of  its  course  by 
the  deltoid,  to  which  it  is  in  a  great  measure  distributed.  Some  twigs  terminate  in  the 
skin  over  the  acromion.  This  acromial  branch  terminates  near  the  acromio-claviculax 
articulation :  sometimes  one  of  its  divisions  closely  follows  the  anterior  border  of  the 
clavicle. 

The  Inferior  or  Long  Thoracic  Artery. 

The  inferior  thoracic,  long  thoracic,  or  external  mammary  artery  (e,  fig.  210),  is  much  lar- 
ger than  the  acromial  thoracic,  and  sometimes  arises  by  a  common  trunk  with  it  or  with 
the  sub-scapular ;  it  is  given  off  from  the  axillary  below  the  pectoralis  minor,  passes 
downward  and  forward  upon  the  side  of  the  thorax,  between  the  pectoralis  major  and 
serratus  magnus,  then  between  the  serratus  and  the  skin,  and  terminates  at  about  the 
sixth  intercostal  space.  During  this  course  it  gives  off  a  great  number  of  branchest  to 
the  lymphatic  glands  in  the  axilla,  to  the  sub-scapularis,  pectoralis  major,  and  serratus 
magnus  muscles,  to  the  second,  third,  fourth,  fifth,  and  sixth 'intercostal  spaces,  to  the 
mamma,  and  to  the  skin.  Not  unfrequently  the  inferior  thoracic  partially  supplies  the 
place  of  the  sub-scapular  artery,  in  which  case  it  is  as  large  as  that  vessel. 

The  Sub-scapular  Artery. 
The  inferior,  common,  or  sub-scapular  artery  (/),  the  largest  branch  of  the  axillary, 
arises  near  the  lower  part  of  the  head  of  the  humerus  opposite  the  lower  border  of  the 
sub-scapular  muscle,  sometimes  by  itself,  sometimes  by  a  common  trunk  with  the  poste- 
rior circumflex,  the  long  thoracic,  or  the  deep  humeral  artery ;  in  the  last  case  it  is  as 
large  as,  perhaps  even  larger  than,  the  brachial.  At  its  origin,  which  is  from  the  outer 
aspect  of  the  axillary,  it  has  the  musculo-spiral  nerve  to  its  inner  side,  and  the  principal 
orig;in  of  the  median  on  its  outer  side  ;  it  passes  in  a  tortuous  manner  downward  and  out- 
ward along  the  lower  border  of  the  sub-scapularis  muscle,  parallel  with  the  teres  major, 
and  beneath  the  head  of  the  humerus,^  furnishes  large  branches  to  all  these  muscles, 
and  having  arrived  below  the  insertion  of  the  sub-scapularis,  divides  into  two  branches, 
a  descending  or  thoracic,  and  a  scapular,  properly  so  called. 

*  I  hare  seen  two  cases  of  rupture  of  the  axillary  artery  from  attempts  to  reduce  old  dislocations. 

t  [These  branches  represent  the  alar  thoracic  artery,  and  sometimes  arise  directly  from  the  axillary,  behind 
the  pectoralis  minor,  or  from  the  sub-scapular.] 

t  The  relation  of  the  sub-scapular  artery  to  the  head  of  the  humerus  appears  to  me  to  be  important.  In 
abduction  thi«  artery  is  much  stretched,  and  I  am  surprised  that  it  has  not  been  torn  in  same  cases  of  luxation  ; 
on  the  contrary,  the  circumflex  artery,  and,  therefore,  the  circumflex  nerve,  appear  to  me  to  be  much  less  lia 
ble  to  be  stretched  during  abduction.  Nevertheless,  it  is  certain  that  the  circumflex  nerve  has  been  lacerated 
in  some  dislocations  of  the  humerus,  because  they  have  been  followed  by  paralysis  of  the  deltoid  muscle. 


THE  BRACHIAL  ARTERY.  543 

The  descending  or  thoracic  branch  (g),  which  is  often  given  off  by  the  inferior  or  long 
thoracic,  passes  downward  and  forward  near  the  axillary  border  of  the  scapula,  parallel 
with  and  behind  the  long  thoracic,  and  divides  into  a  great  number  of  large  branches, 
some  of  which  enter  the  latissimus  dorsi,  several  penetrate  the  serratus  magnuseven  as 
far  as  the  lowest  portion  of  that  muscle,  while  others  turn  round  the  lower  angle  of  the 
scapula,  and  anastomose  with  the  following  or  scapular  branch,  and  with  the  posterior 
scapular  derived  from  the  sub-clavian. 

The  scapular  branch  (i),  properly  so  called,  proceeds  along  the  lower  border  of  the  sub- 
scapularis  muscle,  in  front  of  the  long  head  of  the  triceps,  and  having  reached  below  the 
scapular  attachment  of  the  triceps,  divides  into  three  branches  :  an  anterior  or  sub-scapu- 
lar branch,  which  dips  into  the  sub-scapular  fossa  below  the  muscle,  and  expands  into  a 
great  number  of  branches,  the  highest  of  which  are  distributed  to  the  capsule  of  the 
shoulder-joint ;  an  infra-spinous  branch  (Jb,fig.  209),  which  turns  round  the  axillary  border 
of  the  scapula,  runs  between  the  muscle  and  the  infra-spinous  fossa,  and  anastomoses, 
by  a  considerable  branch,  with  the  termination  of  the  supra-scapular  artery ;  a  median 
branch  (c,fig.  209),  which  continues  in  the  original  course  of  the  vessel,  runs  along  the 
axillary  border  of  the  scapula,  between  the  teres  major  and  minor,  then  becomes  poste- 
rior, and  terminates  by  anastomosing  again  upon  the  lower  angle  of  the  scapula  with  the 
thoracic  branch  of  this  artery,  and  with  the  infra-spinous  branches  of  the  supra-scapular. 

The  Posterior  Circumflex  Artery. 

The  posterior  circumflex  artery  (Z,  fig.  210)  arises  from  the  back  of  the  axillary  opposite 
the  sub-scapular,  which  it  sometimes  equals  in  size.  It  passes  horizontally  backward, 
between  the  sub-scapularis  above  and  the  teres  major  below,  turns  inward  round  the 
surgical  neck  of  the  humerus,  passing  first  between  the  internal  head  of  the  triceps  and 
the  teres  minor,  then  between  the  long  head  of  the  triceps  and  the  bone,  and  finally  (Jl,fig. 
209)  under  the  deltoid,  to  the  deep  surface  of  which  it  is  applied  ;  it  always  turns  round 
so  as  to  describe  three  fourths  of  a  circle,  and  thus  reaches  the  anterior  and  outer  aspect 
of  the  humerus,  and  is  lost  in  the  deltoid  by  anastomosing  with  the  deltoid  branches  of 
the  acromio-thoracic  artery.  In  the  whole  of  its  course  it  is  accompanied  by  the  cir- 
cumflex vein  and  the  circumflex  nerve.  As  it  turns  round  the  bone,  the  posterior  cir- 
cumflex gives  off  some  articular  and  periosteal  branches,  which  pass  to  the  capsular  lig- 
ament of  the  shoulder-joint,  and  to  the  periosteum  of  the  humerus. 

The  Anterior  Circumjlex  Artery. 
The  anterior  circumflex,  a  small  artery  {n,fig.  210),  sometimes  represented  by  several 
branches,  arises  from  the  axillary  in  front  of  the  posterior  circumflex,  and  often  by  a 
common  trunk  with  it.  It  passes  horizontally  outward  above  the  conjoined  tendons  of 
the  latissimus  dorsi  and  teres  major,  covered  by  the  coraco-brachialis  and  the  short  head 
of  the  biceps,  runs  beneath  the  tendon  of  the  long  head  of  the  biceps,  turns  round  the 
neck  of  the  humerus,  crosses  the  bicipital  groove  at  right  angles,  being  held  down  by 
the  synovial  membrane,  and  divides  into  an  ascending  and  a  descending  branch.  The 
Jatter  presents  nothing  remarkable  ;  but  the  ascending  branch,  having  reached  the  up- 
per part  of  the  groove,  anastomoses  with  the  osseous  branch  of  the  acromial  artery, 
and  is  lost  in  the  head  of  the  humerus,  which  it  penetrates  at  one  or  more  points.  The 
anterior  circumflex  is,  therefore,  intended  for  the  humerus,  its  periosteum,  and  the  syno- 
vial membrane  of  the  groove.  Sometimes  there  are  several  anterior  circumflex  arteries, 
which  enter  the  substance  of  the  deltoid  muscle. 

The  Brachial  Akteky. 

The  brachial  or  humeral  artery  (a'  h,fig.  210)  is  that  portion  of  the  artery  of  the  upper 
extremity  which  extends  from  the  lower  border  of  the  axilla  to  the  point  of  its  bifurca- 
tion at  the  upper  part  of  the  forearm.  It  passes  downward,  and  a  little  forward  and 
outward,  so  that  it  is  situated  on  the  inner  side  of  the  humerus  above,  and  in  front  of  it 
below.  The  absence  of  any  bendings  in  this  artery  explains  the  possibility  of  its  being 
torn  from  extreme  extension  of  the  forearm  in  dislocations  of  the  elbow,  &c.* 

The  relations  of  the  brachial  artery  require  to  be  examined  separately  along  the  arm, 
and  in  front  of  the  elbow-joint. 

Along  the  arm,  the  artery  is  in  relation,  in  front,  with  the  coraco-brachialis  and  the  in- 
ner margin  of  the  biceps,  which  may  be  regarded  as  the  satellite  muscle  of  the  artery  : 
in  emaciated  subjects  the  biceps  does  not  cover  the  artery,  which  is  then  situated  im- 
mediately under  the  fascia ;  behind,  it  is  in  relation  with  the  triceps,  and  then  with  the 
brachialis  anticus  ;  on  the  inner  side,  with  the  fascia  of  the  arm,  which  separates  it  from 
the  skin  ;  on  the  outer  side,  with  the  coraco-brachialis,  then  with  the  inner  side  of  the  hu- 
merus, from  which  it  is  separated  by  the  tendon  of  the  coraco-brachialis,  and  in  the  rest 
of  its  extent  with  the  cellular  interval  between  the  biceps  and  the  brachialis  anticus. 
The  brachial  artery  is  enclosed  in  a  fibrous  sheath,  which  is  common  to  it  and  the  me- 

*  In  old  subjects,  the  humeral  artery  is  almost  always  tortuous,  and  sometimes  these  windings  are  so  re- 
markable that  the  artery  is  sub-aponeurotic  during  a  portion  of  its  course. 


6)44  ANGEIOLOGY. 

dian  nerve.  The  following  are  its  relations  with  the  veins  and  nerves  :  the  principal 
brachial  vein  is  situated  on  its  inner  side  ;  another  smaller  vein  is  on  its  outer  side : 
both  are  in  contact  with  the  artery,  which  they  separate  from  the  nerves,  and  they  are 
connected  by  several  transverse  branches,  which  embrace  the  artery. 

The  median  nerve  is  situated  in  front  of  the  artery,  excepting  above,  where  it  is  on 
its  outer  side,  and  below,  near  the  elbow,  where  it  passes  to  its  inner  side  ;  the  median 
nerve  sometimes  crosses  behind  the  artery.*  The  ulnar  nerve  is  placed  on  the  inner 
side  of  the  artery  above,  then  passes  behind  it,  and  is  lodged  in  a  separate  sheath.  The 
musculo-spiral  nerve  is  situated,  together  with  the  deep  humeral  artery,  at  first  behind 
the  brachial,  but  soon  leaves  it  to  turn  round  the  humerus  ;  lastly,  the  internal  cutane- 
ous follows  the  same  course  as  the  vessel,  crossing  it  slightly  from  before  backward. 

From  these  relations,  it  follows  that  the  vessel  may  be  most  eificaciously  compressed 
from  within  outward,  against  the  inner  surface  of  the  humerus,  and  also  that  it  may  be 
tied  in  any  part  of  its  course. 

At  the  bend  of  the  elbow,  the  brachial  artery  occupies  the  middle  of  the  articulation  ;  it 
is  superficial  in  front,  where  it  is  only  separated  from  the  skin  by  the  fascia  and  tendi- 
nous expansion  of  the  biceps,  and  by  the  median  basilic  vein,  which  crosses  it  at  a  very 
acute  angle  ;  behind,  it  rests  upon  the  brachialis  anticus,  by  which  it  is  separated  from 
the  elbow-joint ;  on  its  inner  side  is  the  median  nerve  and  pronator  teres  muscle,  and, 
on  its  outside,  the  tendon  of  the  biceps,  over  which  it  soon  crosses,  and,  farther  outward, 
the  supinator  longus. 

In  consequence  of  the  superficial  position  of  the  brachial  artery  at  the  bend  of  the  el- 
bow, and  from  its  relations  with  the  median  basilic  vein  and  the  elbow-joint,  it  follows 
that  this  artery  may  be  easily  compressed,  may  be  wounded  in  the  operation  of  vene- 
section, and  may  be  lacerated  in  dislocations  of  the  joint,  t 

Collateral  Branches. — These  may  be  divided  into  the  external  and  anterior,  and  the  inter- 
nal and  posterior. 

The  external  and  anterior  are  very  numerous,  and  are  intended  for  the  coraco-brachia- 
lis  and  biceps,  which  they  penetrate  at  different  heights,  and  also  for  the  brachialis  an- 
ticus. A  very  remarkable  branch,  which  appears  to  me  to  be  constant,  viz.,  the  deltoid, 
passes  transversely  in  front  of  the  humerus,  beneath  the  coraco-brachialis  and  the  biceps, 
and  terminates  partly  in  the  deltoid  at  its  humeral  insertion,  and  partly  in  the  brachialis 
anticus.  The  internal  and  posterior  branches  are  small,  excepting  those  which  enter  the 
brachialis  anticus  directly  :  I  have  seen  them  all  arise  from  the  axillary  by  a  large  branch 
given  off  from  a  common  trunk  with  the  sub-scapular  and  the  posterior  circumflex  arteries. 

Whatever  may  be  their  mode  of  origin,  four  of  these  collateral  branches  are  remark- 
able for  their  regular  distribution,  viz.,  the  deep  humeral,  the  internal  collateral,  the  super- 
ficial branch  for  the  internal  portion  of  the  triceps,  and  the  superficial  branch  for  the  brachi- 
alis anticus.     The  two  former  only  have  received  particular  names. 

The  deep  humeral  artery  {profunda  superior,  k,  fig.  210),  called  aJso  the  external  collateral, 
from  its  terminating  on  the  outer  side  of  the  articulation  of  the  elbow,  arises  from  the 
brachial,  opposite  the  lower  border  of  the  teres  major.  It  occasionally  comes  off  by 
a  common  trunk  with  the  posterior  circumflex,  which,  in  that  case,  arises  from  the 
brachial  instead  of  the  axillary  artery.  It  passes  downward  and  backward,  gains  the 
groove  for  the  musculo-spiral  nerve,  and  traverses  the  whole  extent  of  that  groove  to- 
gether with  the  nerve.  In  this  part  of  its  course  it  is  situated  between  the  triceps  mus- 
cle and  the  humerus,  as  it  turns  round  the  posterior  surface  of  that  bone  ;  below  the  in- 
sertion of  the  deltoid  it  emerges  from  the  groove,  between  the  brachialis  anticus  and  the 
triceps,  and  divides  into  a  deep  branch,  which  continues  with  the  nerve,  and  a  superficial 
branch.  The  former  is  distributed  essentially  to  the  triceps  muscle,  and  sometimes 
comes  off  directly  from  the  brachied  ;  it  passes  vertically  downward  in  the  substance 
of  the  triceps,  supplies  its  internal  and  external  portions,  and  terminates  in  them  by 
anastomosing  freely  with  the  collateral  branches  situated  around  the  elbow-joint.  The 
superficial  branch  perforates  the  external  head  of  the  triceps,  and  the  external  inter-mus- 
cular septum,  along  which  it  descends  vertically  to  the  back  of  the  epicondyle,  or  external 
condyle  of  the  humerus,  where  it  anastomoses  with  the  interosseous  recurrent  artery. 

The  internal  or  ulnar  collateral  artery  {profunda  inferior,  m,  figs.  210,  211)  is  much 
smaller  than  the  external  collateral,  from  which  it  is  sometimes  derived ;  it  is  often 
double.  It  usually  arises  at  a  variable  height  from  the  lower  part  of  the  brachial,  some- 
times passes  transversely  inward,  and  sometimes  proceeds  in  a  tortuous  manner  down- 
ward before  becoming  transverse,  and  then  divides  into  two  branches  :  one  anterior,  which 
is  distributed  to  the  brachialis  anticus,  the  muscles  attached  to  the  epitrochlea  or  internal 
condyle  of  the  humerus,  and  the  periosteum  upon  that  process  ;  the  other  posterior,  which 
perforates  the  internal  intermuscular  septum,  and  divides  into  muscular  branches  for  the 

*  Dubreuil  has  seen  that  arrangement  in  three  cases  ;  and  M.  Chassignac  has  met  with  it  twice  last  winter. 

t  I  have  seen  this  artery  lacerated  in  a  case  of  luxation  forward  of  the  humerus  on  the  forearm,  in  conse- 
quence of  a  fall  from  a  horse  upon  the  wrist.  The  lower  extremity  of  the  humerus  had  torn  the  brachialis 
anticus,  the  artery  and  the  skin  through  which  it  had  passed.  A  hemorrhage,  followed  by  syncope,  took 
place  at  the  moment  of  the  accident.  The  patient  having  been  carried  to  her  residence  in  this  swoon,  the 
reduction  was  accomjdished,  the  hemorrhage  did  not  return,  and  the  cure  was  as  perfect  as  possible. 


THE  BRACHIAL  AATEEY.  545 

triceps ;  into  periosteal  and  osseous  branches,  which  pass  transversely  in  front  of  the 
triceps,  and  anastomose  with  the  interosseous  recurrent ;  and  into  a  descending  branch, 
which  accompanies  the  ulnar  nerve,  and  anastomoses  with  the  posterior  ulnar  recurrent. 

The  superficial  branch  for  the  internal  portion  of  the  triceps  is  remarkable  for  its  size  and 
length ;  it  arises  from  the  brachial,  inunediately  below  the  profunda  superior,  from  which 
also  it  is  rather  frequently  derived,  and  passes  vertically  downward  applied  to  the  idnar 
nerve.  It  is  at  first  situated  in  front  of  the  internal  intermuscular  septum,  then  perfo- 
rates it,  accompanied  by  the  idnar  nerve,  and,  passing  backward  between  the  epitrochlea 
and  the  olecranon,  aneistomoses  with  the  posterior  ulnar  recurrent. 

The  superficial  branch  for  the  braehialis  anticus  arises  from  the  brachial  artery  at  the 
same  height  as  the  preceding,  runs  along  the  inner  side  of  the  braehialis  anticus,  grad- 
ually diminishing  in  size  down  to  the  lower  part  of  the  arm,  where  it  anastomoses  with 
the  internal  collateral  artery.* 

The  terminal  branches  of  the  brachial  are  the  radial  (jp,figs.  210,  211)  and  ulnar  (g)  ar- 
teries. The  bifurcation  of  the  brachial  artery  into  the  radial  and  ulnar  usually  takes 
place  below  the  bend  of  the  elbow,  sometimes  on  a  level  with  it,  but  rather  frequently 
above  the  articular  line  ;  in  the  latter  case,  the  bifurcation  has  been  observed  to  occur 
sometimes  at  the  lower  third  or  at  the  middle  of  the  arm,  sometimes  at  the  junction  of 
the  upper  with  the  two  lower  thirds,  and  sometimes  in  the  axilla  itself,  the  radial  and 
ulnar  arteries  immediately  succeeding  to  the  axillary.  In  these  cases,  one  division  of 
the  artery,  generally  the  radial,  is  sub-cutaneous,  while  the  ulnar  assumes  the  ordinary 
relations  of  the  brachial ;  but  the  reverse  of  this  may  take  place  ;  and,  lastly,  the  radial 
and  the  ulnar  have  both  been  found  sub-cutaneous.  Not  unfrequently,  the  radial  artery, 
at  its  origin,  is  the  inner  branch  of  the  bifurcation,  and  then  crosses  the  ulnar  at  a  very 
acute  angle,  in  order  to  reach  the  radius.  Besides  these  anomalies  resulting  from  va- 
rieties in  the  point  of  bifurcation,  there  is  yet  another,  in  which  a  premature  division  takes 
place  into  two  branches,  one  of  which  forms  the  interosseous  artery,  and  the  other  the 
brachial,  which  has  its  usual  arrangements ;  at  other  times,  instead  of  a  bifurcation, 
only  a  very  slender  branch  is  given  off,  and  terminates  in  the  ulnar,  which  in  that  case 
arises  by  two  roots. 

The  frequency  of  high  divisions  of  the  humeral  artery  require  that  the  practical  con- 
siderations to  which  these  give  rise  should  be  taught.  If,  therefore,  a  hemorrhage  by 
the  arteries  of  the  forearm  should  not  yield  to  a  ligature  of  the  humeral  artery,  we  should, 
with  M.  Danyau,  suspect  the  high  division  of  the  humeral  artery,  and  search  for  the 
other  branch. 

Here  follows  the  minute  description  of  three  rare  varieties  which  I  have  exhibited  at 
the  Anatomical  Society.  From  the  inferior  part  of  the  axillary  artery  arose  a  slender  ar- 
tery, which  first  coursed  all  along  the  humeral  artery,  on  the  inside  of  which  it  was  situ- 
ated ;  it  then  crossed  this  vessel  by  passing  before  it  at  the  union  of  the  two  superior  with 
the  inferior  third  of  the  arm,  and  finally  joined  the  radial  artery  opposite  the  bicipital  tu- 
berosity of  the  radius. 

At  the  bend  of  the  elbow,  this  artery,  which  might  be  considered  as  a  slender  branch 
of  origin  of  the  radial  artery,  occupied  the  same  relations  as  the  humeral  artery,  and 
was  situated  below  the  aponeurotic  expansion  of  the  biceps,  while  the  trunk  of  the  hu- 
meral artery  was  not  placed  under  this  expansion,  but  below  the  tendon  of  the  biceps. 
It  was  behind  this  tendon,  a  little  above  its  insertion  into  the  radius,  that  the  humeral 
artery  was  divided  into  radial  and  ulnar  ;  the  radial,  instead  of  coursing  directly  down- 
ward, described  a  curve  with  the  concavity  inward  ;  and  it  was  with  the  lower  part  of 
this  curve  that  the  long  and  feeble  branch  coming  from  the  axillary  artery  united. 

I  have  met,  again,  a  similar  anomaly,  with  this  difference,  that  the  long  and  slender 
arterial  branch,  instead  of  going  to  the  radial,  anastomosed  with  the  ulnar.  This  variety 
may  be  considered  as  a  mode  of  anastomosis  between  the  upper  and  the  lower  part  of 
an  arterial  trunk,  a  mode  of  anastomosis  by  a  collateral  canal,  unusual  in  the  arterial,  but 
very  frequent  in  the  venous  system. 

In  a  case  where  one  of  the  branches  of  the  high  division  was  the  interosseous  artery, 
and  the  other  the  common  trunk  of  the  radial  and  ulnar  arteries,  the  respective  relations 
of  these  vessels  were  as  follows  : 

The  humeral  dichotomic  division  took  place  below  the  hollow  of  the  axilla.  One  of 
the  branches  was  the  common  trunk  of  the  interosseous  arteries,  which  first  followed 
the  usual  course  of  the  humeral  artery,  then  crossed,  at  a  very  acute  angle,  the  other 
branch  by  passing  behind  it,  coursed  obliquely  downward  and  outward,  and  finally  reach- 
ed the  external  border  of  the  tendon  of  the  biceps.  Having  been  sub-aponeurotic  so  far, 
it  now  dipped  under  the  pronator  teres,  gave  off  the  radial  and  ulnar  recurrent  branches. 
iQd  terminated  as  the  interosseous  arteries  terminate. 

ITie  other  branch  constituted  the  common  trunk  of  the  radial  and  cubital  arteries ; 

*  [These  two  superficial  braaches  are  frequently  represented  in  their  distributioo  by  a  sing-le  branch,  nailed 
the  anastomotic  artery  (u,figs.  210,  211),  which  arises  from  the  brachial,  about  two  inches  above  the  elbow. 

The  nutritious  artery  of  the  humerus  is  small,  but  constant :  it  as-ises  from  the  outer  side  of  the  brachial,  or 
one  of  its  collateral  branches,  passes  downward,  perforates  the  insertion  of  the  coraco-lwachialis  muscle,  and 
enters  the  oblique  foramen  in  the  inner  side  of  the  humerus,  to  ramify  in  the  aicduilary  c«nal  of  that  bone  1 

Z  2  Z 


546  AN6EI0L06T. 

sub- aponeurotic,  like  the  preceding,  it  reached  the  anterior  side  of  the  epitrochlea,  and 
divided  into  two  secondary  branches  :  one  internal,  which  was  the  ulnar,  a  little  tortu- 
ous, coursed  downward  as  far  as  the  annular  carpal  ligament ;  the  other  external,  which 
was  the  radial,  passed  obliquely  downward  and  outward  as  far  as  the  radial  insertion  of 
the  pronator  teres,  when  it  became  vertical.  During  their  whole  course,  the  radial  and 
ulnar  arteries  were  sub-aponeurotic. 

I  have  been  on  the  point  of  opening  the  radial  artery  at  the  bend  of  the  arm,  in  a 
case  where  it  lay  over  the  superficial  tendon  of  the  biceps.* 

A  knowledge  of  these  anomahes,  both  in  reference  to  the  point  of  bifurcation  and  to 
the  new  relations  of  the  parts,  is  extremely  important  to  the  surgeon. 

The  Radial  Artery  and  its  Branches. 

Dissection. — The  radial  artery  in  the  forearm  is  completely  exposed  by  dissecting  the 
supinator  longus ;  the  carpal  portion  of  the  artery  by  dissecting  the  tendons  of  the 
thumb  opposite  the  vnrist ;  the  palmar  portion  by  dividing  all  the  flexor  tendons  in  the 
palm.  It  is,  therefore,  advisable  to  postpone  the  examination  of  the  palmar  portion  of 
the  artery  until  the  ulnar  has  been  studied. 

The  raAial  artery  (j),figs.  210,  211),  the  outer  of  the  two  branches  into  which  the  brach 
ial  divides,  is  more  superficial  and  smaller  than  the  ulnar ;  it  extends  from  the  point 
of  bifurcation  of  the  brachial  down  to  the  peilm  of  the  hand.  Sometimes  the  radial  turns 
backward,  after  having  reached  the  lower  third  of  the  forearm,  and  remains  sub-cutane- 
ous until  it  dips  between  the  first  and  second  metacarpal  bones  ;  its  place  in  front  of  the 
lower  part  of  the  radius  is  then  supplied  by  the  radio-palmar  artery  or  superficialis  volaj, 
which  is  extremely  small.  It  is  very  common  to  find  the  radial  artery  of  one  arm  larger 
than  that  of  the  other ;  in  one  case  I  found  both  radials  wanting  in  front  of  the  lower 
part  of  the  radius. 

Tlie  radial  artery  is  at  first  directed  downward,  and  somewhat  obliquely  outward,  like 
the  brachial,  with  the  direction  of  which  it  corresponds  ;  it  then  descends  vertically  as 
far  as  the  lower  end  of  the  radius,  turns  round  the  anterior  surface  and  apex  of  the  sty- 
loid process,  to  gain  the  outer  side  of  the  carpus,  and  passes  obliquely  downward  and 
backward,  to  reach  the  upper  part  of  the  first  interosseous  space  ;  there  it  turns  abrupt- 
ly forward,  between  the  upper  extremities  of  the  first  and  second  metacarpal  bones, 
passing  between  the  two  origins  of  the  first  dorsal  interosseous  muscle,  enters  the  palm 
of  the  hand,  and  runs  almost  transversely  inward,  to  form  the  deep  palmar  arch  {b,  Jig. 
211).  The  radial  artery  is  frequently  tortuous  at  the  lower  part  of  the  forearm.  From 
the  long  course  and  the  direction  of  the  radied,  it  may  be  divided  into  three  portions, 
corresponding  to  the  forearm,  the  wrist,  and  the  palm  of  the  hand. 

The  first  jiortion  of  the  radial  artery,  viz.,  that  situated  in  the  forearm,  has  the  following  re- 
lations :  In  front,  with  the  inner  border  of  the  supinator  longus,  which  overlaps  it,  especial- 
ly above  ;  in  the  rest  of  its  extent  it  lies  beneath  the  fascia.  In  emaciated  subjects  the  su- 
pinator longus  is  narrow,  and  this  part  of  the  artery  is  sub-aponeurotic  in  its  whole  extent. 

Behind,  it  corresponds  to  the  anterior  surface  of  the  radius,  from  which  it  is  separated 
above  by  the  supinator  brevis  ;  lower  down  by  the  pronator  teres,  and  by  the  radial  ori- 
gins of  the  flexor  sublimis  and  flexor  longus  poUicis  ;  still  lower  by  the  pronator  quadra- 
tus,  below  which  it  rests  directly  upon  the  inferior  portion  of  the  radius.  The  superficial 
position  of  the  radial  artery,  and  the  support  afforded  it  by  the  bone,  are  the  reasons 
why  it  is  chosen  for  examining  the  pulse. 

On  the  inner  side,  it  is  in  relation  with  the  pronator  teres,  then  with  the  tendon  of  the 
flexor  carpi  radialis,  along  which  it  runs,  and  which  is  on  a  plane  anterior  to  it ;  so  that 
the  contraction  of  this  muscle,  by  causing  its  tendon  to  project,  renders  the  pulsations 
of  the  vessel  more  difficult  to  be  felt. 

On  the  outer  side,  it  is  in  relation  with  the  supinator  longus,  and  in  the  middle  part  of 
its  course  with  the  radial  nerve  (the  continuation  of  the  musculo-spiral),  which  is  situ- 
ated at  some  distance  from  it,  both  above  and  below,  and  has  a  separate  fibrous  sheath. 

Of  the  collateral  branches  of  the  radial  artery  in  the  forearm,  only  three  require  a  special 
description,  viz.,  the  anterior  radial  recurrent,  the  anterior  carpal  branch,  and  the  radio- 
palmar  artery. 

The  anterior  radial  recurrent  artery  {r,figs.  210,  211)  is  given  off  from  the  back  part, 
and  immediately  below  the  origin  of  the  radial.  It  is  very  large  in  some  subjects,  in- 
deed as  large  as  the  radial  itself :  it  descends  a  little,  and  then  turning  upward,  so  as  to 
describe  a  curve  with  its  convexity  directed  downward,  it  ascends  between  the  supina- 
tor longus  and  the  brachialis  anticus,  in  order  to  anastomose  with  that  part  of  the  pro- 

*  The  editor,  engaged  as  he  has  been,  for  thirty  years,  in  teaching  anatomy,  has  had  very  extensive  oppor- 
tunities of  observing  varieties  in  the  origins  of  the  radial  and  ulnar  arteries ;  and  as  the  result  of  these,  he 
would  state  as  a  general  rule,  liable  to  very  few  exceptions,  1st.  When  the  radial  arises  prematurely,  it  pass- 
es, like  the  humeral,  under  the  aponeurotic  expansion  of  the  biceps  muscle. 

2d.  When  the  ulnar  arises  above  the  elbow,  it  passes  superficially  above  this  aponeurosis,  being  placed  sub- 
cutaneous in  connexion  with  th«  veins. 

The  editor  believes,  that  in  the  majority  of  cases  where  an  artery  is  wounded  in  performing  the  operation  of 
jloodletting  at  the  bend  of  the  arm,  the  vessel  injured  is  the  ulnar,  which  has  arisen  prematurely.  In  several 
cases  where  he  has  been  called  on  to  operate  for  aneurism  produced  by  this  accident,  he  has  found  this  to  he 
the  case. 


THE   RADIAL    ARTERY.  549 

fimda  superior  which  forms  the  external  collateral  branch  of  the  elbow.    I  have  seen 
this  recurrent  artery  arise  from  the  ulnar. 

From  the  convexity  of  the  arch  described  by  the  radial  recurrent,  a  great  number  of 
branches  proceed  obliquely  downward  and  outward,  and  are  distributed  to  all  the  raus 
cles  on  the  external  aspect  of  the  forearm,  viz.,  the  long  and  short  supinators,  and  the 
two  radial  extensors.  One  of  these  branches  passes  transversely  between  the  long  supi- 
nator and  the  long  radial  extensor,  to  anastomose  on  the  outer  condyle  with  the  profun- 
da artery ;  others  pass  between  the  radius  and  the  muscles  attached  to  it,  ramifying  in 
the  extensor  muscles  of  the  forearm,  and  anastomose  with  the  posterior  interosseous 
artery  derived  from  the  ulnar. 

The  anterior  carpal  branch  of  the  radial  artery  is  a  small  branch  {a,  fig.  211)  which 
passes  transversely  inward  at  the  lower  margin  of  the  pronator  quadratus  muscle,  and 
anastomoses  with  a  similar  branch  from  the  ulnar  artery. 

The  radio-palmar  or  superficial  palmar  artery  {superficialis  voIcf,,  s,  fig.  210)  arises  at  an 
acute  angle  from  the  inner  side  of  the  radial,  at  the  point  where  that  vessel  turns  out- 
ward to  pass  over  the  carpus.  Sometimes  its  origin  is  situated  at  the  junction  of  the 
lower  with  the  two  upper  thirds  of  the  forearm.  It  varies  much  in  its  size  and  distribu- 
tion ;  most  commonly  it  passes  vertically  downward,  on  a  level  with  the  anterior  liga- 
ment of  the  carpus,  perforates  the  origin  of  the  short  abductor  of  the  thumb,  and  anasto- 
moses with  the  extremity  of  the  superficial  palmar  arch  {t)  of  the  ulnar  (g).  Several 
branches  arise  from  its  convexity,  and  are  distributed  to  the  muscles  and  integuments 
of  the  ball  of  the  thumb.  The  radio-palmar  branch  is  frequently  very  small,  is  entirely 
lost  in  those  muscles,  and  does  not  assist  in  the  formation  of  the  superficial  palmar  arch. 
On  the  contrary,  it  is  often  so  large  that  it  may  be  regarded  as  formed  by  the  bifurcation 
of  the  radial,  and  then  assists  as  much  as  the  ulnar  in  forming  the  superficial  palmar 
arch.  In  some  cases  in  which  the  superficial  palmar  arch  did  not  exist,  I  have  seen  the 
radio-palmar  give  origin  to  the  internal  collateral  artery  of  the  thumb,  both  collateral  ar- 
teries of  the  index,  and  the  external  collateral  of  the  middle  finger,  the  ulnar  artery  fur- 
nishing the  collaterals  of  the  other  fingers.  In  one  case,  a  transverse  branch,  resembling 
the  anterior  communicating  artery  of  the  brain,  formed  the  anastomosis  between  the  ra- 
dio-palmar and  the  ulnar  arteries. 

The  second  or  carpal  portion  of  the  radial  artery  extends  from  the  styloid  process  of  the 
radius  to  the  upper  part  of  the  first  interosseous  space.  Closely  applied  to  the  ligaments 
and  bones  of  the  carpus,  it  passes  at  first  obliquely  downward  and  inward,  and  then  be- 
comes vertical  as  it  dips  into  the  interosseous  space,  to  pass  between  the  two  heads  of 
the  first  dorsal  interosseous  muscle.  It  is  well  protected  on  the  outer  side  of  the  carpus 
by  the  projecting  tendons  of  the  two  extensors  and  the  long  abductor  of  the  thumb,  edl 
of  which  cross  it  obliquely,  and  separate  it  from  the  skin ;  but  between  the  tendons  of 
the  long  abductor  of  the  thumb  and  the  long  radial  extensor  it  becomes  sub-aponeurotic, 
and  therefore  very  superficial.     In  this  short  course  it  gives  off  several  branches. 

The  dorsal  carpal  branch  of  the  radial  artery,  more  remarkable  for  its  constancy  and 
the  mode  of  its  distribution  than  for  its  size,  which  is  inconsiderable,  arises  opposite  the 
articulation  of  the  two  rows  of  carpal  bones,  passes  transversely  inward,  and  terminates 
either  by  being  lost  in  the  adjacent  parts,  or  by  anastomosing  with  the  corresponding 
branch  of  the  ulnar  artery.  From  the  arch  thus  formed  proceed  certain  ascending  branch- 
es, which  anastomose  with  twigs  from  the  anterior  interosseous  artery,  sometimes  ap- 
pearing to  form  the  termination  of  that  vessel,  which,  as  we  shall  presently  describe,  be- 
comes posterior  at  the  lower  part  of  the  forearm ;  and  also  some  descending  branches,  of 
very  variable  size,  which,  having  reached  the  upper  part  of  the  third  and  fourth  interos- 
seous spaces  in  peirticular,  anastomose  with  the  perforating  branches  of  the  deep  palmar 
arch,  and  form  ope  of  the  origins  of  the  small  twigs,  which  are  named  the  dorsal  interos- 
seous arteries  of  those  spaces. 

The  dorsal  interosseous  branch  for  the  second  space,  known  also  as  the  dorsal  metacarpal 
branch  of  the  radial  artery,  is  sometimes  so  large  that  it  seems  to  be  a  continuation  of 
the  radial,  and  at  other  times  very  small,  and,  as  it  were,  a  mere  vestige.  It  often  ari- 
ses by  a  common  trunk  with  the  dorsal  carpal  branch  just  described ;  it  runs  along  the 
dorsal  surface  of  the  second  interosseous  space,  and,  having  reached  the  lower  part  of 
it,  gives  superficial  dorsal  arteries  to  the  index  and  middle  fingers,  and  then  bends  for 
ward  between  the  heads  of  the  second  and  third  metacarpal  bones,  to  anastomose  witli 
that  digital  branch  of  the  superficial  palmar  arch  which  gives  off  the  internal  collateral 
artery  of  the  index,  and  the  external  collateral  artery  of  the  middle  finger.* 

The  interosseous  artery  of  the  first  space  is  so  large  that  it  is  described  as  formed  by  the 
bifurcation  of  the  radial :  it  arises  from  that  artery  between  the  first  and  second  meta- 
carpal bonesj  and  sometimes  runs  along  the  dorsal  aspect  of  the  first  interosseous  space, 
and  at  others  between  the  first  dorsal  interosseous  muscle  and  the  adductor  poUicis  ;  in 

*  [Three  small  branches,  two  of  which  usually  arise  by  a  common  trunk,  are  given  off  from  the  radial  ar- 
tery near  the  dorsal  aspect  of  the  head  of  the  first  metacarpal  bone  ;  two  of  them  form  the  superficial  dorsal 
arteries  of  the  two  sides  of  the  thumb  {dorsales  pollids),  while  the  other  is  the  dorsal  artery  of  the  radial  side 
•f  the  indtx  finger  {dorsahs  indicis).'i 


$4^  AN6ET0LO6Y. 

«ther  case,  when  it  reaches  the  lower  part  of  the  space,  it  divides  into  two  branches, 
which  may  arise  separately  from  the  carpal  portion  of  the  radial  artery,  as  in^^.  211, 
and  which  constitute  the  internal  collateral  artery  of  the  thumb  and  the  external  collateral 
artery  of  the  index  finger  (x).  The  external  collateral  artery  of  the  thumb,  sometimes  deri- 
ved from  the  preceding,  or  even  from  the  extremity  of  the  superficial  palmar  arch,  cross- 
es the  muscles  of  the  ball  of  the  thumb  obliquely,  to  reach  the  outer  side  of  its  metacar- 
po-phalangal  articulation  (v,fig.  210),  and  runs  along  the  outer  border  of  the  thumb.* 

The  Deep  Palmar  Arch. 

The  third  or  'palmar  portion  of  the  radial  artery  constitutes  the  dee'p  palmar  arch  (i,  fig. 
211),  which  is  completed  by  inosculating  with  a  branch  of  the  ulnar,  in  the  same  man- 
ner as  we  have  seen  the  superficial  palmar  arch  of  the  ulnar  artery  completed  by  a  branch 
of  the  radial.  This  arch  is  situated  deeply  across  the  front  of  the  metacarpal  bones,  im- 
mediately below  their  upper  extremities  ;  it  rests  immediately  upon  them  and  the  inter- 
osseous muscles,  and  is  therefore  subjacent  to  all  the  nerves,  tendons,  and  muscles  (ex- 
cept the  interosseous)  in  the  palm  of  the  hand.  The  deep  palmar  arch  describes  a  slight 
curve,  the  convexity  of  which  is  directed  downward.  I  have  seen  the  palmar  arch  form- 
ed by  the  dorsal  artery  of  the  second  interosseous  space,  which  then  dipped  between  the 
upper  ends  of  the  second  and  third  metacarpal  bones. 

The  deep  palmar  arch  gives  off  very  short  superior  or  ascending  branches  {recurrentes), 
which  are  lost  in  front  of  the  carpus,  anastomosing  with  the  anterior  carpal  branches  of 
the  radial  and  ulnar  arteries  ;  also  some  descending  or  palmar  interosseous  arteries  (d  d, 
interosseae  volares,  Holler),  three  or  four  in  number,  which  descend  vertically  along  the 
interosseous  spaces,  and  anastomose  with  the  descending  digital  branches  (cut  across  in 
fig.  211)  of  the  superficial  palmar  arch,  either  opposite  or  above  their  bifurcation  into 
the  collateral  arteries  of  the  fingers.  The  size  of  the  palmar  interosseous  arteries  is  ex- 
tremely variable,  as  well  as  that  of  the  deep  palmar  arch  itself;  it  bears  an  inverse  pro- 
portion to  that  of  the  superficial  palmar  arch  and  its  branches.  The  relative  size  of  the 
difierent  palmar  interosseous  arteries,  also,  varies  much ;  most  generally  the  first  is  the 
largest,  at  other  times  the  second,  and  occasionally  the  third. 

The  deep  palmar  arch  also  gives  off  the  posterior  or  perforating  branches  (c  c).  These 
are  three  in  number,  and  form  for  the  second,  third,  and  fourth  interosseous  spaces  what 
the  radial  itself  is  for  the  first,  with  this  difference,  that  the  radial  perforates  the  first 
space  from  behind  forward,  while  these  perforating  branches  traverse  the  corresponding 
spaces  from  before  backward.  They  arise  from  behind  the  deep  palmar  arch,  and  imme- 
diately perforate  the  upper  part  of  the  interosseous  spaces  in  a  straight  line,  and  having 
reached  the  dorsal  aspect  of  the  hand,  generally  anastomose  with  the  corresponding  dor- 
sal interosseous  arteries,  which,  in  a  great  number  of  cases,  are  formed  entirely  by  these 
perforating  branches.  In  some  subjects,  the  dorsal  interosseous  arteries  result  from  the 
anastomoses  of  the  perforating  arteries  with  the  interosseous  arteries  derived  from  the 
dorsal  carpal  arch  formed  by  the  dorsal  carpal  branches  of  the  radial  and  ulnar  arteries  ; 
they  pass  vertically  downward  on  the  dorsal  surface  of  the  interosseous  spaces,  and  hav- 
ing reached  their  lower  parts,  anastomose  with  the  descending  digital  branches  of  the 
superficial  palmar  arch,  and  thus  assist  in  the  formation  of  the  collateral  arteries  of  thp 
fingers. 

The  Ulnar  Artery  and  its  Branches. 

The  ulnar  artery  {g,figs.  210,  211),  which  is  larger  than  the  radial,  leaves  that  vessel 
at  a  very  acute  angle,  passes  at  first  downward,  inward,  and  backward,  in  front  of  the 
ulna,  describing  a  slight  curve,  the  convexity  of  which  is  directed  upward  and  inward,  and 
then  descends  vertically.  Having  arrived  at  the  wrist,  it  is  placed  on  the  outer  or  radi- 
al side  of  the  pisiform  bone,  in  front  of  the  annular  ligament  of  the  carpus,  and  then 
enters  the  pahn  of  the  hand,'where  it  describes  beneath  the  palmar  fascia  an  arch,  which 
has  its  convexity  turned  downward,  and  is  named  the  superficial  palmar  arch  {t,fig.  210 ; 
removed  in^^.  211). 

The  relations  of  the  ulnar  artery  must  be  separately  examined  in  the  forearm  and  in 
the  hand. 

In  the  forearm,  it  is  at  first  covered  by  the  thick  bundle  of  muscles  which  are  attached 
to  the  inner  condyle  of  the  humerus,  and  also  by  the  median  nerve,  from  which  it  is  sep- 
arated by  that  part  of  the  pronator  teres  which  arises  from  the  coronoid  process  ;  it  is 
then  covered  by  the  flexor  sublimis,  and  finally  by  the  fascia  and  skin  ;  the  tendon  of  the 
flexor  carpi  ulnaris  is  upon  its  inner  side,  and  that  of  the  flexor  sublimis  on  its  outer  : 
these  two  tendons,  by  their  projection,  occasion  an  interval  between  the  artery  and  the 
skin.  It  is  in  relation  behind  with  the  brachialis  anticus,  the  flexor  profundus  digitorum, 
and  the  pronator  quadratus.    The  ulnar  nerve  is  applied  to  the  inner  side  of  the  artery 

*  [The  two  collateral  arteries  of  the  thumb,  and  the  external  collateral  of  the  index  finger,  frequently  arise 
in  a  different  manner  from  that  described  above  :  thus,  the  two  arteries  for  the  thumb  may  take  origin  from  a 
common  trunk,  which  is  then  named  the  great  or  principal  artery  of  the  thumb  (magna  vel  princeps  pollicis) , 
while  the  artery  for  the  index  finger  arises  separately,  and  is  named  the  radial  collateral  artery  of  the  index 
Unger  (radialis  indicis).1 


THE    ULNAR    ARTERY. 


mi 


I!^.  211. 


at  the  point  where  the  vessel  becomes  vertical,  and  accompanies  it  as 
far  as  the  hand.  The  median  nerve  is  situated  on  its  inner  side  at  the 
bend  of  the  elbow,  but  afterward  becomes  anterior,  and  then  external 
to  it.  In  some  cases  of  high  division  of  the  humeral  artery,  the  ulnar 
has  been  found  immediately  under  the  fascia  in  its  whole  length. 

In  the  hand,  it  is  at  first  situated  on  the  outer  or  radial  side  of  the 
pisiform  bone,  and  then  in  front  of  the  hook-like  process  of  the  unci- 
form bone  ;  finally,  where  it  forms  the  superficial  palmar  arch,  it  is 
entirely  sub-aponeurotic. 

In  the  forearm,  the  ulnar  artery  gives  off  a  great  number  of  un- 
named collateral  branches,  which  are  divided  into  internal,  external, 
anterior,  and  posterior,  and  are  distributed  to  the  muscles  and  integ- 
uments. Four  branches,  however,  require  special  notice,  viz.,  in 
the  forearm,  the  common  trunk  of  the  ulnar  recurrents,  the  interosseous 
artery,  the  branch  for  the  median  nerve,  and  the  anterior  artery  of  the 
carpus;  in  the  palm  of  the  hand,  the  ulnar  artery  gives  off  the  collet- 
erai  arteries  of  the  fingers. 

The  anterior  arid  posterior  ulnar  recurrent  arteries  generally  arise 
by  a  common  trunk,  which  is  given  off  from  the  back  of  the  highest 
portion  of  the  ulnar  artery,  passes  transversely  inward,  and  divides 
into  two  branches — an  anterior  and  a  posterior.  The  former,  or  an- 
terior ulnar  recurrent  artery  {e,fig.  211),  passes  between  the  brachialis 
anticus  and  pronator  teres,  gives  branches  to  all  the  muscles  attach- 
ed to  the  inner  condyle,  and  anastomoses  with  the  internal  collateral 
branch  from  the  brachial.  The  other  branch,  the  posterior  ulnar  re- 
current, is  larger  than  the  anterior,  runs  behind  the  muscles  arising 
from  the  inner  condyle,  is  then  situated  between  that  condyle  and 
the  olecranon,  passes  between  the  two  origins  of  the  flexor  carpi 
ulnaris  in  front  of  the  ulnar  nerve,  anastomoses  freely  with  the  in- 
ternal collateral  branch  of  the  brachial  artery  and  with  the  interosseous  recurrent,  and 
contributes  to  form  an  arterial  network  upon  the  back  of  the  elbow-joint.  The  branch 
given  off  by  the  posterior  ulnar  recurrent  to  the  ulnar  nerve  deserves  to  be  pointed  out ; 
it  may  be  traced  from  below  upward,  along  that  nerve,  and  anastomoses  with  the  other 
branches  given  off  to  the  same  nerve  from  the  brachial  artery. 

The  interosseous  artery  is  so  large  that  it  appears  to  be  the  result  of  a  bifurcation  of  the 
ulnar,  and  is  described  as  such  by  many  anatomists  ;  it  comes  off  from  the  back  of  the 
ulnar,  immediately  below  the  trunk  of  the  recurrents,  on  a  level  with  the  bicipital  tuber- 
osity of  the  radius ;  it  not  unfrequently  arises  from  the  radial.  Lastly,  in  several  cases 
of  high  division,  either  of  the  brachial  or  of  the  axillary  artery,  the  interosseous  has  been 
found  to  constitute  one  of  the  branches  of  the  bifurcation,  the  other  branch  being  the 
common  trunk  of  the  radial  and  ulnar  arteries. 

Immediately  after  its  origin,  the  interosseous  passes  directly  backward,  and  divides 
into  two  branches  of  almost  equal  size,  which  are  named,  from  their  distribution,  the  an- 
terior and  posterior  interosseous. 

The  anterior  interosseous  if  fig-  211)  descends  vertically  in  front  of  the  interosseous 
ligament,  and  is  held  down  to  it  by  a  layer  of  fibrous  tissue  ;*  it  is  placed  behind  the 
flexor  profundus  digitorum  and  the  flexor  longus  pollicis,  in  the  cellular  interval  between 
these  muscles.  Having  reached  the  upper  borders  of  the  pronator  quadratus,  it  passes 
between  that  muscle  and  the  interosseous  ligament,  rests  upon  the  latter,  and  perforates 
it  towards  its  lower  part ;  having  thus  reached  the  back  of  the  forearm,  the  anterior  in- 
terosseous descends  upon  the  dorsal  surface  of  the  carpus,  and  terminates  by  anastomo- 
sing with  the  dorsal  carpal  branches  of  the  radial  and  ulnar.  While  perforating  the  in- 
terosseous ligament  behind  the  pronator  quadratus,  the  artery  almost  always  gives  off  a 
small  twig,  which  descends  perpendicularly  to  join  the  arch  formed  by  the  anterior  ar- 
teries of  the  carpus. 

In  one  case  where  the  radial  artery  was  exceedingly  small,  indeed  in  a  rudimentary 
state,  its  place  was  supplied  by  the  anterior  interosseous ;  which,  after  having  passed 
behind  the  pronator  quadratus,  escaped  forward  under  the  lower  border  of  that  muscle, 
and  passed  transversely  outward,  to  anastomose  with  the  rudimentary  radial  artery, 
which,  thus  re-enforced,  immediately  assumed  its  usual  size. 

During  its  course,  the  interosseous  artery  only  gives  off  some  small  branches  to  the 
front  of  the  forearm,  among  which  the  artery  of  the  median  nerve  deserves  special  notice ; 
but  several  large  branches  are  detached  in  succession  from  its  posterior  aspect,  and  im- 
mediately perforate  the  interosseous  ligament :  they  are  called  the  perforating  arteries  of 
the  forearm,  and  are  distributed  to  the  deep  layer  of  muscles  on  the  back  of  the  forearna. 
I  have  seen  one  of  these  run  along  the  posterior  surface  of  the  interosseous  ligament,  in 
the  same  manner  as  the  anterior  interosseous  artery. 

*  After  amputation  of  the  forearm,  the  interosseous  artery  becomes  retracted  between  thi«  fibrous  layer  and 
the  interosseous  ligament ;  and  it  is  hence  so  difficult  in  some  cases  to  place  a  ligature  upon  it,  that  it  haa 
been  recommended  to  divide  the  inte"-=«^"~  '■    -•nent  for  a  short  distance. 


ANGEIOLOGY. 

The  artery  of  the  median  nerve  is  remarkable  for  its  constancy  and  its  length ;  it  comes 
,  off  from  the  front  of  the  anterior  interosseous  artery,  reaches  the  posterior  surface  of  the 
median  nerve,  penetrates  it,  and  then  runs  downward  along  its  inner  side.  I  have  seen 
the  artery  of  the  median  nerve  very  large,  and  anast9mosing  with  the  superficial  pahnar 
ar<3h.  It  has  also  been  found  continuous  with  the  brachial  artery,  and  supplying  the 
place  of  both  the  radial  and  ulnar,  which  were  in  a  rudimentary  state. 

The  posterior  interosseous  artery  is  generally  smaller  than  the  anterior ;  it  perforates 
the  interosseous  ligament  opposite  the  lower  border  of  the  supinator  brevis,  and  imme- 
diately gives  off  an  ascending  branch,  the  interosseous  recurrent ;  it  then  descends  be- 
tween the  deep  and  superficial  layer  of  muscles  on  the  back  of  the  forearm,  and  divides 
into  a  number  of  branches,  which  are  distributed  to  those  muscles,  but  especially  to  the 
superficial  layer.* 

The  interosseous  recurrent  is  a  branch  of  the  posterior  interosseous,  of  such  size  that  it 
may  be  regarded  as  resulting  from  the  bifurcation  of  that  artery  :  it  passes  vertically  up- 
ward, having  the  anconeous  and  the  extensor  carpi  ulnaris  behind  it,  and  the  supinator 
brevis  in  front  of  it ;  it  runs  behind  the  inner  condyle,  and  anastomoses  on  the  outer  side 
of  the  elbow-joint  with  the  cutaneous,  muscular,  and  periosteal  divisions  of  the  superior 
profunda  artery,  the  external  collateral  branch  of  the  brachial 

The  anterior  carpal  branch  of  the  ulnar  artery  is  a  small  twig,  which  arises  opposite  the 
lower  borders  of  the  pronator  quadratus,  passes  between  the  tendon  of  the  flexor  carpi 
ulnaris  and  the  ulna,  and  anastomoses  with  a  similar  branch  from  the  radial,  to  form  the 
anterior  carpal  arch,  from  which  several  branches  descend  to  reach  the  interosseous 
muscles,  and  those  of  the  ball  of  the  thumb  - 

The  Superficial  Palmar  Arch. 

Opposite  the  articulation  between  the  two  rows  of  carpal  bones,  and  before  it  forms 
the  superficial  palmar  arch,  the  ulnar  artery  gives  off  a  deep  branch  backward,  called  the 
radio-cubital,  or  communicating  artery  {y,fig-  210),  which  dips  between  the  short  abduc- 
tor and  short  flexor  of  the  little  finger,  then  passes  outward  between  the  short  flexor  and 
opponens,  to  anastomose  with  and  complete  the  deep  palmar  arch.  This  artery  is  some- 
times so  large  that  it  may  be  regarded  as  formed  by  the  bifurcation  of  the  ulnar 

The  superficial  palmar  arch  (t,fig.  210),  which  constitutes  the  termination  of  the  ulnar, 
gives  off  no  important  branch  from  its  upper  or  concave  side.  Four  or  five  diverging  digi- 
tal branches  pass  from  its  lower  or  convex  side,  and  constitute  the  collateral  arteries  ol 
the  fingers. 

The  digital  branches  (w  u  u)  are  distinguished  as  the  first,  second,  third,  and  fourth, 
proceeding  from  within  outward.  The  first  reaches  the  inner  or  ulnar  border  of  the  lit- 
tle finger,  and  constitutes  its  internal  collateral  artery ;  the  second  runs  along  the  fourth 
interosseous  space,  and  divides  into  the  external  collateral  artery  of  the  little  finger,  and  the 
internal  collateral  artery  of  the  ring  finger ;  the  third  runs  along  the  third  interosseous  space, 
and  supplies  the  external  collateral  artery  of  the  ring  finger  and  the  internal  collateral  artery 
of  the  middle  finger ;  the  fourth  runs  in  the  second  interosseous  space,  and  gives  the  ex- 
ternal collateral  artery  of  the  middle  finger  and  the  internal  collateral  artery  of  the  index  fin- 
ger. It  is  very  rare  to  find  the  external  collateral  artery  of  the  index  finger  (x),  and  the 
internal  collateral  of  the  thumb  derived  from  the  superficial  palmar  arch ;  and  still  more 
rare  to  see  the  external  collateral  artery  of  the  thumb  (r)  given  off  by  that  arch. 

Whatever  varieties  there  may  be  in  the  arteries  of  the  palm  of  the  hand,J  in  reference 
to  the  share  which  the  radial  and  ulnar  respectively  take  in  the  formation  of  the  collat- 
eral arteries  of  the  fingers,  the  following  general  facts  are  apparent  in  their  distribution  : 
The  size  of  the  superficial  and  deep  palmar  arches  respectively  are  always  inversely  pro- 
portioned to  each  other ;  the  communication  between  the  two  arches  takes  place  not 
only  directly  between  the  arches  themselves,  but  also  indirectly  in  a  great  number  of 
points  by  their  branches  ;  all  the  descending  branches  of  the  deep  palmar  arch  anasto- 
mose with  the  angle  of  bifurcation  of  the  descending  branches  of  the  superficial  palmar 
arch :  those  from  the  deep  arch  are  sometimes  smaller,  sometimes  larger  than  those 

*  Some  branches  may  oe  traced  as  far  aa  the  carpus. 

t  [There  are  usually  two  other  branches  given  from  the  ulnar  in  the  vrrist :  the  first  is  a  dorsal  metacarpal 
branch,  which  arises  above  the  anterior  carpal,  runs  under  the  tendon  of  the  flexor  ulnaris,  turns  round  the 
ulna  to  reach  the  back  of  the  carpus,  anastomoses  with  the  dorsal  metacarpal  branch  of  the  radial,  and  sends 
a  twig  along  the  fifth  metacarpal  bone,  to  form  the  superficial  dorsal  artery  of  the  little  finger.  The  second 
branch  of  the  ulnar  in  this  situation  may  arise  with  the  one  just  described  ;  it  is  a  posterior  or  dorsal  carpal 
branch,  which  passes  backward,  and  anastomoses  beneath  the  extensor  tendons  with  the  dorsal  carpal  branch 
of  the  radial  artery.] 

i  In  one  case  the  superficial  palmar  arch  was  formed  in  the  most  regular  manner  by  the  radial  and  the  ul- 
nar arteries,  which  concurred  in  its  formation  by  two  perfectly  equal  trunks,  and  gave  off  the  collateral  branch- 
es to  all  the  fingers  except  the  external  collateral  of  the  thumb,  the  internal  collateral  of  the  index,  and  the 
external  collateral  of  the  middle  finger. 

The  deep  palmar  arch,  very  small  in  comparison  with  the  superficial  palmar  arch,  which  was  very  consider- 
able, was  formed  as  usual.  It  gave  off  the  external  collateral  of  the  thumb  and  the  common  trunk  of  the  in- 
ternal collateral  of  the  index,  and  the  external  collateral  of  the  middle  finger.  This  common  trunk  was  the 
continuation  of  the  non-flexed  portion  of  the  radial  artery.  The  radial  artery  in  this  case  was  much  larger 
than  the  ulnar. 


REMARKS   ON   THE    ARTERIES    OF   THE   UPPER    EXTREMITY.  551 

trom  the  superficial  arch ;  they  are  rarely  of  the  same  size,  but  always  bear  an  inverse 
ratio  to  them ;  the  bifurcation  of  each  digital  branch  of  the  superficial  pahnar  arch  takes 
place  two  or  three  lines  below  the  metacarpo-phalangal  articulation,  opposite  the  junc- 
tion of  the  body  with  the  upper  end  of  the  first  phalanx ;  the  collateral  arteries  of  the 
fingers  are  situated  upon  the  anterior  aspect  of  the  phalanges,  on  each  side  of  the  sheath 
of  the  flexor  tendons  ;  they  give  off  dorsal  and  palmar  branches,  and  anastomose  with 
each  other  in  front  of  the  body  of  the  phalanges  by  small  transverse  branches  ;  having 
reached  the  middle  of  the  last  phalanx,  they  anastomose  in  an  arch,  from  the  convexity 
of  which  a  great  number  of  anterior  branches  pass  to  the  skin,  over  the  last  phalanx,  and 
some  dorsal  branches  to  the  matrix  of  the  nail ;  one  of  these  branches  runs  along  the 
curved  adherent  border  of  the  nail. 

The  termination  of  the  superficial  palmar  arch  is  subject  to  variety:  thus,  it  terminates 
either  by  anastomosing  with  the  radio-palmar  or  superficialis  volae,  of  the  same  size  as 
itself,  or  by  receiving  a  very  small  radio-palmar  branch,  and  being  prolonged  so  as  to  con- 
stitute the  common  trunk  of  the  internal  collateral  artery  of  the  thumb,  and  the  external 
collateral  artery  of  the  index  finger ;  or  else  it  terminates  in  the  external  collateral  of 
that  finger ;  or,  lastly,  after  having  given  off  the  internal  collateral  of  the  thumb  and  the 
external  collateral  of  the  fore-finger,  it  ends  in  the  external  collateral  of  the  thumb.  At 
other  times,  again,  there  is  no  superficial  palmar  arch  properly  so  called,  and  the  ulnar 
artery  terminates  by  furnishing  the  collaterals  of  the  little  and  ring  fingers,  and  the  in- 
ternal collateral  of  the  middle  finger,  the  other  collaterals  being  derived  from  the  radio- 
palmar,  which  is  then  very  large.  In  certain  cases,  a  very  small  transverse  branch  forms 
the  communication  between  the  radial  and  the  ulnar  arteries. 

General  Remarks  on  the  Arteries  of  the  Upper  Extremity. 

A  single  trunk,  which  may  be  called  the  brachial  trunk,  supplies  the  whole  of  the  up- 
per extremity ;  it  forms,  in  succession,  the  sub-clavian,  the  axillary,  and  the  brachial  ar- 
tery, which  latter  bifurcates  near  the  bend  of  the  elbow  into  the  radial  and  ulnar  arteries : 
these  form  the  palmar  arteries,  from  which  the  arteries  of  the  fingers  take  their  origin. 

The  difference  in  the  origin  of  the  right  and  left  brachial  trunks  has  been  considered 
to  account  for  the  difference  in  strength  between  the  two  arms  ;  and  the  different  size 
of  the  two  vessels  has  also  been  supposed  to  be  connected  with  the  same  fact,  which, 
however,  in  reality,  depends  upon  the  more  frequent  exercise  of  the  right  than  of  the 
left  arm. 

The  brachial  trunk  is  not  exclusively  distributed  to  the  upper  extremity,  but  supplies 
the  most  dissimilar  parts  ;  a  fact  which  shows  that  the  conditions  of  origin,  which  have 
so  great  an  influence  in  regard  to  nerves,  are  altogether  without  importance  in  reference 
to  the  arteries.  Thus,  the  brachial  trunk  sends  branches  to  the  following  parts  :  the  ver- 
tebral artery  to  the  brain,  the  cerebellum,  the  pons  varolii,  the  medulla  oblongata,  and 
the  spinal  cord ;  the  inferior  thyroid  artery,  to  the  thyroid  gland,  the  larynx,  the  trachea, 
the  oesophagus,  and  sometimes  the  bronchi ;  the  internal  mammary  and  thoracic  arteries, 
to  the  corresponding  manrnia ;  and  the  same  arteries,  together  with  the  superior  inter- 
costal, to  the  parietes  of  the  thorax  and  abdomen ;  the  ascending  cervical,  to  the  praever- 
tebral  muscles  and  the  spine ;  and,  lastly,  the  deep  cervical,  sub-scapular,  and  posterior 
scapular  arteries,  to  the  superficial  and  deep  muscles  of  the  back  of  the  neck. 

Setting  aside  those  branches  which  do  not  belong  to  the  upper  extremity  properly  so 
c^ed,  we  find  that,  during  its  course  along  the  limb,  the  artery  always  occupies  the  as- 
pect of  flexion,  which  is  at  the  same  time  the  position  where  it  can  be  best  protected ; 
and  that,  for  this  purpose,  it  is  directed  from  the  axilla  to  the  bend  of  the  elbow :  we 
find,  also,  that  it  gives  off  a  great  number  of  anastomotic  branches  around  the  articula- 
tions, and  thus  establishes  a  collateral  circulation,  through  which  the  blood  can  pass 
when  the  principal  artery  is  obliterated.  This  anastomosis,  and,  consequently,  the  col- 
lateral circulation,  is  effected  by  the  cutaneous,  muscular,  and  periosteal  branches,  and 
even  by  those  distributed  to  the  nerves.  Thus,  along  the  clavicle,  we  find  the  acromio- 
thoracic  in  front,  and  the  supra-scapular  or  transversus  humeri  behind ;  around  the  scap- 
ula there  are  the  supra-scapular  on  the  upper  border,  the  posterior  scapular  on  the  ver- 
tebral border,  and  the  sub-scapular  on  the  axillary  border ;  so  that  that  bone  is  complete- 
ly surrounded  by  an  anastomotictriangle. 

Around  the  elbow-joint  are  the  external  and  internal  collateral  branches  of  the  brach- 
ial artery,  and  the  radial,  ulnar,  and  interosseous  recurrents. 

Around  the  wrist  we  find  the  anterior  and  posterior  carpal  arteries,  and  also  anasto- 
motic arches  around  the  metacarpo-phalangal  and  phalangal  articulations. 

On  comparing  the  size  and  number  of  the  arteries  of  the  arm  and  forearm  with  the 
size  and  number  of  the  arteries  of  the  hand,  it  will  be  seen  that  the  latter  has  greatly 
the  advantage  :  indeed,  in  this  part  of  the  body,  there  is  an  unusual  distribution  of  the 
arterial  system  into  a  deep  and  a  superficial  set  of  vessels,  precisely  as  is  the  case  with 
the  veins.  Why  is  this  \  Is  it  not  extremely  probable  that,  as  the  deep  veins  are  in- 
tended to  supply  the  place  of  the  superficial,  when  the  circulation  in  the  latter  is  for  a 
time  impeded,  so  in  the  hand  the  arteries  are  arranged  in  a  similar  manner,  because  the 


bS2  ANGEIOLOGY. 

superficial  circulation  is  liable  to  be  interrupted  by  pressure  from  grasping  hard  bodies 
firmly  in  the  hand  for  a  longer  or  shorter  period  1  and  is  it  not  for  the  same  reason  that 
the  superficial  system  derived  from  the  ulnar  artery  has  so  many  communications  with 
the  deep  system  given  off  from  the  radial  1 

It  is  virorthy  of  remark  that  the  radial,  which  is  the  superficial  eirtery  of  the  forearm, 
becomes  deep-seated  in  the  hand  ;  and  that  the  ulnar,  which  is  deep-seated  in  the  fore- 
arm, becomes  superficial  in  the  hand. 

The  great  quantity  of  blood  circulated  through  the  hand  is  connected  with  the  active 
use  of  that  part,  in  the  ahnost  constant  exercise  of  the  sense  of  touch,  and  in  prehension 


ARTERIES  ARISING  FROM  THE  TERMINATION  OF  THE  AORTA 

Enumeration. — The  Middle  Sacral. — The  Common  Iliacs. — The  Internal  Iliac,  or  Hypogas- 
tric— the  Umbilical — the  Vesical — the  Middle  Hemorrhoidal — the  Uterine — the  Vaginal — 
the  Obturator — the  Uio-lumbar — the  Lateral  Sacral — the  Glutceal — the  Sciatic — the  Inter- 
nal Pudic. — Summary  of  the  Distribution  of  the  Internal  Iliac. — Artery  of  the  Lower  Ex- 
tremity.— The  External  Iliac — the  Epigastric — the  Circumflex  Iliac. — The  Femoral — the 
Superficial  Epigastric — the  External  Pudic — the  Muscular — the  Deep  Femoral,  its  Cir- 
cumflex and  Perforating  Branches. — The  Popliteal  and  its  Collateral  Branches. — The  An- 
terior  Tibial  and  the  Dorsal  Artery  of  the  Foot. — The  Tibio-peroneal — Peroneal — Poste- 
rior Tibial,  and  the  Internal  and  External  Plantar. — Comparison  between  the  Arteries  of 
the  Upper  and  Lower  Extremities. 

The  arteries  arising  from  the  termination  of  the  aorta  are  the  middle  sacral  and  the 
two  common  iliac  arteries. 

The  Middle  Sacral  Artery. 

The  middle  or  anterior  sacral  artery  {n,fig.  199),  the  small  median  artery  of  the  sacrum, 
arises  from  the  lower  and  back  part  of  the  aorta,  a  little  above  its  termination.  Like 
the  aorta,  it  is  a  single  vessel,  and  seems  to  be  the  continuation  of  it,  as  far  as  direction 
is  concerned  ;  which,  indeed,  is  really  the  case  in  such  animals  as  are  provided  with  a 
tail.  Sometimes,  but  rarely,  it  arises  from  the  left  common  iliac,  or  the  last  lumbar  ar- 
tery. I  have  seen  it  arise  by  a  common  trunk  with  the  two  lower  lumbar  arteries.*  It 
passes  vertically  downward  in  front  of  the  fifth  lumbar  vertebra,  the  sacrum  and  the 
coccyx  being  closely  applied  to  them  all.  It  is  situated  in  the  median  line  at  its  origin, 
but  sometimes  deviates  to  one  side  or  the  other.  In  size  it  is  scarcely  equal  to  one  of 
the  lumbar  arteries,  and  it  gradually  diminishes  from  its  origin  to  the  first  bone  of  the 
coccyx,  towards  the  apex  of  which  it  terminates  in  a  very  variable  manner. 

The  size  of  the  middle  sacral  is  generally  inversely  proportioned  to  that  of  the  lowest 
lumbar  arteries.  When  the  aorta  divides  higher  than  ordinarily,  and  the  last  lumbar  is 
given  off  from  the  middle  sacral,  the  last-named  artery  is  of  course  unusually  large. 

During  its  course,  the  middle  sacral  gives  off,  opposite  the  fifth  lumbar  and  each  of 
the  sacral  vertebrae,  a  right  and  left  lateral  branch,  which  correspond  with  the  series  of 
intercostal  and  lumbar  arteries.  The  two  lumbar  branches  are  generally  small,  but  are 
very  large  when  the  fifth  lumbar  arteries  are  neither  furnished  by  the  aorta,  nor  by  the 
fourth  lumbar,  nor  by  the  ilio-lumbar.  The  lateral  branches  given  off  upon  the  sacrum 
pass  transversely  outward,  supply  twigs  to  the  periosteum  and  bone,  and  anastomose 
with  the  lateral  sacral,  the  place  of  which  they  sometimes  supply  within  the  interior  of 
the  sacral  canal. 

The  middle  sacral  having  become  very  slender  near  the  base  of  the  coccyx,  bifurcates 
in  order  to  form  an  anastomotic  arch  with  the  right  and  left  lateral  sacral  arteries.  I 
have  seen  its  lower  end  divided  into  three  branches,  of  which  the  median  was  prolonged 
as  far  as  the  tip  of  the  coccyx,  while  the  lateral  branches  anastomosed  with  the  lateral 
sacral  arteries. 

The  Common  Iliac  Aeteeies. 
The  primitive  or  common  iliac  arteries  (i  i,  figs.  199,  212),  the  two  branches  into  which 
the  aorta  subdivides,  commence  opposite  the  lower  margin  of  the  fourth  lumbar  vertebra, 
and  terminate  by  bifurcating  opposite  the  base  of  the  sacrum  ;  they  separate  from  each 
other  at  an  acute  angle,  pass  obliquely  downward  and  outward,  and  form  the  two  sides 
of  an  isosceles  triangle,  the  base  of  which  corresponds  with  the  transverse  diameter  of 
the  fifth  lumbar  vertebra.  These  arteries  are  generally  straight,  but  not  unfrequently 
they  are  tortuous  in  aged  persons.  In  the  adult  they  are  about  two  inches  long,  the 
right  being  rather  longer  than  the  left,  from  the  position  of  the  aorta  ;  but  they  are  often 
much  shorter,  on  account  of  their  bifurcating  higher  than  usual.  Meckel  has  remarked 
that  this  premature  bifurcation  is  more  common  on  the  left  than  on  the  right  side.  In 
a  specimen  deposited  in  the  museum  of  the  Ecole  de  Medecine,  the  right  common  iliac 

*  1  have  geen  the  middle  sacral  artery  arise  from  the  renal  artery.  In  this  case,  the  renal  artery  came  frtau 
the  angle  of  bifurcation  of  tke  aorta. 


THE    INTERNAL    ILIAC    ARTERY.  553 

is  entirely  wanting  ;  the  aorta  dividing  into  three  branches,  two  on  the  right,  viz.,  the  in- 
ternal and  external  iliacs,  and  one  on  the  left,  viz.,  the  common  iliac,  which  is  distributed 
in  the  usual  manner.  In  this  case  the  descending  aorta  resembled,  to  a  certain  extent, 
the  ascending  aorta,  and,  like  it,  gave  off  three  trunks 

Relations. — They  are  covered  by,  and  loosely  connected  with,  the  peritoneum  ;  they 
are  crossed  by  the  ureters  and  the  spermatic  vessels,  besides  which,  the  left  common  il- 
iac is  crossed  by  the  inferior  mesenteric  artery ;  they  are  surrounded  by  a  great  number 
of  lymphatic  glands,  and  rest  above  upon  the  vertebral  column,  and  on  the  outside  and 
below  upon  the  inner  side  of  the  psoas  muscle. 

It  is  of  great  importance  to  comprehend  their  relations  with  the  common  iliac  veins. 
The  veins  are  situated  behind  the  arteries ;  but  as  the  right  and  left  vein  unite  on  the 
right  side  of  the  vertebral  column,  the  left  common  iliac  vein  comes  into  relation  with 
both  common  iliac  arteries. 

The  common  iliac  artery  gives  off  no  collateral  branch  ;  it  merely  supplies  some  twigs 
to  the  cellular  tissue,  the  lymphatic  glands,  and  the  coats  of  the  common  iliac  veins.  It 
occasionally  gives  off  one  of  the  renal  arteries ;  and  it  has  been  seen  to  supply  the  sper- 
matic and  the  ilio-lumbar  arteries. 

Terminal  Branches. — The  common  iliac  artery  terminates  by  dividing  into  two  branch- 
es, which  remain  in  contact  with  each  other  for  a  short  distance :  the  internal  branch 
dips  into  the  pelvis,  and  is  called  the  internal  iliac  or  hypogastric  artery ;  tlie  external 
branch  continues  in  the  original  course  of  the  common  iliac,  and  is  termed  the  external 
iliac  artery. 

Thk  Internal  Iliac  or  Hypogastric  Artery. 

The  internal  iliac  or  hypogastric  artery  {t,figs.  199,  212)  is  distributed  to  all  the  organs 
contained  in  the  cavity  of  the  pelvis ;  to  the  muscles  pig,  212. 

which  line  it  within  and  cover  it  without ;  to  the  exter- 
nal and  internal  organs  of  generation,  and  to  the  integ- 
uments. 

It  passes  at  first  obliquely  downward  and  forward, 
and,  as  it  were,  in  contact  with  the  external  iliac ;  it 
then  dips  vertically  into  the  pelvis  in  front  of  the  sacro- 
iliac synchondrosis,  describing  a  short  curve  ;  and,  after 
a  course  of  about  one  inch  or  one  inch  and  a  half  in  length, 
divides  opposite  the  upper  part  of  the  sacro-sciatic  notch 
into  a  greater  or  less  number  of  branches,  which  do  not 
always  arise  in  the  same  way  from  the  principal  trunk, 
but  whose  ultimate  distribution  is  constant.  It  is  cov- 
ered by  peritoneum,  and  is  crossed  by  the  ureter ;  it  rests 
behind  on  the  lumbo-sacral  nerve  and  pyriformis  muscle*; 
and  the  internal  iliac  vein  is  behind  and  to  its  outer  side. 

Its  branches,  all  of  which  sometimes  arise  from  two 
principal  trunks,  one  anterior  and  the  other  posterior,  may  be  divided  into  an  antenar 
set,  consisting  of  the  umbilical,  vesical,  obturator,  middle  hemorrhoidal,  uterine,  vaginal,  aei- 
atic,  and  internal  pudic  arteries ;  and  a  posterior  set,  including  the  ilio-lumbar,  lateral,  *a- 
cral,  and  gluteal  arteries.     Altogether,  there  are  nine  in  the  male  and  eleven  in  the  female. 

The  Umbilical  Artery. 

The  umbilical  artery,  which  is  so  large  in  the  foetus,  is  converted  into  an  impermeable 
cord  {xt;fig.  212)  in  the  adult,  excepting  near  its  origin  {a),  where  it  gives  off  some  ves- 
ical branches  :  the  examination  of  the  umbilical  arteries  belongs,  therefore,  more  espe- 
cially to  the  anatomy  of  the  foetus.  They  are  intended  to  convey  the  blood  of  the  foetus 
to  the  placenta,  and  are  then  the  continuations  of  the  common  iliac  arteries.  The  ex- 
ternal and  internal  iliacs,  being  very  small  at  that  period,  in  correspondence  with  the 
small  size  of  the  abdominal  extremities,  appear  to  be  nothing  more  than  divisions  of  the 
umbilical. 

The  umbilical  arteries  pass  downward,  forward,  and  outward,  and,  having  arrived  at 
the  sides  of  the  bladder,  run  along  them,  in  order  to  reach  the  umbilical  ring,  through 
which  they  emerge  from  the  abdomen,  and,  having  traversed  the  whole  length  of  the 
umbilical  cord  in  a  spiral  and  tortuous  manner,  are  at  length  distributed  to  the  placenta.* 

The  vesical,  middle  hemorrhoil.il,  uterine,  vaginal,  and  obturator  arteries  are  given 
off  in  succession  from  the  apparently  ligamentous  cord  formed  by  the  umbilical  artery 
near  its  origin. 

The  Vesical  Arteries. 
These  are  variable  in  number :  the  principal  of  them  on  each  side  are  given  off  from 

*  It  is  curious  to  study  the  variable  manner  in  which  the  umbilical  arteries  are  converted,  after  Ijirth,  into 
a  fibrous  tissue.  Sometimes  these  arteries  are  converted  into  two  regular  cords,  which  converge  towards  the 
umbilicus.  At  other  times  each  of  these  cords  is  subdivided  into  irregular  bundles  which  it  is  difficult  to 
trace  to  their  true  origin. 

4A 


654  ANGEIOLOGY. 

the  umbilical  artery  (a),  which  seems  to  be  converted  into  a  ligamentous  cord  (u)  at  the 
place  where  the  vesical  arteries  arise,  but  which  is  in  reality  pervious.  This  ligament- 
ous appearance  of  the  umbilical  arteries  depends  upon  the  narrowness  of  their  canal,  as 
compared  with  the  thickness  of  their  coats.  Other  vesical  branches  arise  from  the  mid- 
dle hemorrhoidal  and  obturator  arteries,  and  in  the  female  from  the  uterine  and  vaginal. 
We  shall  divide  the  vesical  arteries  into  the  posterior,  the  anterior,  and  the  inferior. 

The  posterier  vesical  artery  {b,fig.  212)  frequently  arises,  in  the  female,  by  a  common 
trunk  with  the  uterine.  It  reaches  the  base  of  the  bladder,  on  the  outer  side  of  the  ure- 
ter, passes  inward  and  upward  upon  the  posterior  surface,  as  far  even  as  the  summit  of 
that  viscus.  I  have  seen  the  right  posterior  vesical  artery,  of  large  size,  running  along 
the  posterior  surface  of  the  bladder  in  the  median  line,  and  prolonged  upon  the  urachus ; 
the  left  posterior  vesical  was  very  small,  and,  in  fact,  rudimentary. 

The  anterior  vesical  (c)  arises  from  the  umbilical,  from  the  obturator,  and  sometimes 
from  the  internal  pudic  artery.  When  it  arises  from  the  umbilical,  it  is  given  off  from 
that  artery  opposite  the  sides  of  the  bladder,  and  passes  downward  and  inward  along  its 
anterior  surface.  I  have  seen  it  given  off  near  the  summit  of  that  organ.  When  it  ari- 
ses from  the  obturator  or  the  internal  pudic,  it  traverses  the  anterior  lig2iment  of  the  blad- 
der, and  passes  upward  upon  the  front  of  that  organ. 

I  have  seen  a  very  large  vesical  artery  given  off  from  the  obturator,  which,  in  that 
case,  arose  from  the  epigastric,  and  farther  the  vesical  artery  arose  by  a  common  trunk 
with  the  artery  of  the  corpus  cavernosum. 

The  inferior  vesical  {d),  which  often  arises  direct  from  the  internal  iliac,  reaches  the 
inferior  fundus  of  the  bladder,  and  ramifies  abundantly  upon  it  and  the  commencement 
of  the  urethra :  in  the  male  it  also  supplies  the  corresponding  vesicula  seminalis  and  vas 
deferens,  the  branch  to  which  is  called  the  deferential  artery,  and  the  prostatic  portion 
of  the  urethra.     I  have  seen  the  dorsal  artery  of  the  penis  arise  from  the  inferior  vesical. 

The  Middle  Hemorrhoidal  Artery. 
This  is  a  small  artery  (e),  which  is  sometimes  wanting,  its  place  being  then  supplied 
by  branches  from  different  sources,  but  especially  from  the  sciatic  or  the  internal  pudic  ; 
it  passes  upon  the  sides  of  the  anterior  surface  of  the  rectum,  where  it  terminates  by 
anastomosing  with  the  superior  and  inferior  hemorrhoidal  arteries. 

The  Uterine  Artery. 

The  uterine  artery  {n  n,jig.  198)  arises  from  the  umbilica.,  near  the  posterior  vesical, 
and  frequently  by  a  common  trunk  with  it ;  passes  transversely  inward  to  the  corre- 
sponding lateral  border  of  the  uterus,  a  little  above  the  os  tincae ;  is  reflected  upward 
along  the  uterus,  and  terminates  by  expanding  into  several  ascending  branches,  of  which 
the  anterior  reach  the  front,  the  posterior  the  back,  and  the  middle  the  upper  border  of 
the  viscus,  and  inosculate  either  with  their  fellows  of  the  opposite  side,  or  with  the  uter- 
ine branches  of  the  ovarian  artery.  The  uterine  arteries  are  remarkable  for  the  great 
size  which  they  acquire  during  pregnancy,  and  also  for  their  tortuous  and  spiral  course, 
even  to  their  smallest  branches :  a  disposition  which  no  other  artery  presents  in  the 
same  degree.  These  tortuosities,  instead  of  diminishing,  appear  to  increase  during 
pregnancy :  a  fact  which  seems  opposed  to  the  view  generally  adopted  regarding  the 
use  of  arterial  flexuosities  in  organs  liable  to  variations  in  their  size. 

Collateral  Branches. — At  the  point  of  its  reflection,  each  uterine  artery  gives  off  one  or 
more  descending  branches  between  the  vagina  and  the  bladder  to  supply  both  parts ;  in 
their  course  along  the  borders  of  the  uterus,  they  furnish  a  series  of  anterior  and  poste- 
rior ascending  branches,  which  are  distributed  in  the  same  way  as  the  terminal  ascending 
branches  ;  they  all  anastomose  in  the  median  line  with  their  fellows  of  the  opposite  side. 

Relations. — The  trunks  of  the  uterine  arteries  are  beneath  the  peritoneum  ;  the  prin- 
cipal branches  are  situated  under  a  thin  layer  of  the  substance  of  the  uterus,  and  the  ul- 
timate divisions  and  subdivisions  enter  its  tissue. 

The  Vaginal  Artery. 
The  vaginal  artery  arises  from  the  umbilical,  sometimes  before,  sometimes  after  the 
origin  of  the  uterine,  which  is  sometimes  given  off  from  a  conunon  trunk  with  it.  It  is 
as  large  as  the  uterine  in  young  subjects,  but  is  smaller  than  it  after  puberty.  It  de- 
scends directly  upon  the  sides  of  the  vagina,  to  which  it  gives  off  a  numerous  series  of 
branches,  supplies  a  considerable  branch  to  the  neck  of  the  bladder  and  the  urethra, 
gives  an  equally  large  one  to  the  bulb  of  the  vagina,  and  then  passes  backward  between 
the  orifice  of  the  vagina  and  the  rectum,  and  anastomoses  with  its  fellow  of  the  oppo- 
site side. 

The  Obturator  Artery. 
The  obturator  artery  {f,fig.  212)  is  remarkable  for  the  varieties  of  its  origin,  and  for 
the  important  consequences  which  result  from  those  varieties,  in  reference  to  the  oper- 
ation for  femoral  hernia. 


THE    ILIO-LUMBAR   ARTERY.  SS5 

It  generally  arises  from  the  internal  iliac  by  the  side  of  the  umbilical,  but  sometimes 
above  the  gluteal ;  it  is  almost  as  frequently  given  off  from  the  external  iliac,  either  di- 
rectly,* which  is  rare,  or  by  a  common  trunk  with  the  epigastric.     Lastly,  and  much 
-  more  rarely,  it  arises  from  the  femoral  artery. 

The  course  of  the  obturator  artery  is  modified  by  these  differences  of  origin,  which, 
notwithstanding  the  assertion  of  some  anatomists,  are  as  common  in  the  male  as  the  fe- 
male, and  which  may  occur  on  one  side  only,  or  on  both  sides  of  the  same  subject. 
Thus,  when  the  obturator  comes  from  the  femoral,  it  passes  upward  on  the  inner  side 
of  the  femoral  vein,  enters  the  pelvis  through  the  crural  ring,  is  reflected  upon  the  upper 
surface  of  the  body  of  the  os  pubis,  then  passes  behind  it  and  gains  the  internal  opening 
of  the  sub-pubic  canal.  When  it  arises  by  a  common  trunk  with  the  epigastric,  it  dips 
vertically  behind  the  os  pubis  to  the  same  opening.  In  its  ordinary  mode  of  origin,  it 
passes  horizontally  forward  upon  the  sides  of  the  brim  of  the  pelvis,  being  bound  down 
by  the  peritoneum,  runs  parallel  with  the  obturator  nerve  (n),  which  is  placed  above  i 
gains  with  it  the  internal  orifice  of  the  sub-pubic  canal,  and,  having  traversed  this  pas- 
sage, divides  into  an  internal  and  an  external  terminal  branch. 

Collateral  Branches. — Near  its  origin,  the  obturator  artery  gives  off  a  tolerably  large 
branch,  the  iliac,  which  perforates  the  iliac  fascia,  dips  between  the  iliacus  muscle  and 
the  ihac  fossa,  and  anastomoses  with  a  branch  of  the  circumflex  iliac  artery,  t 

As  it  enters  the  sub-pubic  canal  it  gives  off  a  small  branch,  which  passes  transversely 
behind  the  body  of  the  pubis,  and  ramifies  upon  the  side  of  the  symphysis,  anastomo- 
sing with  its  fellow  of  the  opposite  side  ;  also  a  small  ascending  branch  (s),  which  anas- 
tomoses with  the  epigastric  artery,  and  which  may  be  regarded,  according  to  Meckel,  as 
one  of  the  origins  of  the  obturator ;  so  that  the  variety  in  which  the  obturator  arises 
from  the  epigastric  is  often  nothing  more  than  an  unusual  development  of  this  commu- 
nicating branch.  In  support  of  this  view,  we  may  quote  the  very  rare  case,  in  which 
the  obturator  arises  by  two  roots  of  almost  equal  size,  one  coming  from  the  epigastric, 
and  the  other  from  the  interned  iliac. 

Terminal  Branches. — The  interned  branch  passes  between  the  obturator  extemus  mus- 
cle and  the  conjoined  rami  of  the  pubes  and  ischium,  so  as  to  describe  a  semicircle 
around  the  inner  half  of  the  obturator  foramen,  gives  branches  to  the  periosteum  of  the 
OS  pubis,  muscular  branches  to  the  two  obturator  and  to  the  adductor  muscles,  some 
genital  branches  to  the  coverings  of  the  testis  in  the  male  and  to  the  labia  majora  in 
the  female,  and,  lastly,  some  very  important  anastomotic  branches,  which  join  those  of 
the  internal  circumflex. 

The  external  branch  runs  along  the  outer  half  of  the  obturator  foramen  ;  it  is  placed, 
like  the  preceding,  between  the  two  obturator  muscles,  and  terminates  between  the 
neck  of  the  femur  and  the  quadratus  femoris  muscle  by  anastomosing  with  the  sciatic 
artery.  This  anastomosis  is  very  remarkable.  During  its  course,  the  external  branch 
supplies  the  obturator  muscles  and  the  hip-joint ;  the  articular  branch  enters  by  the 
notch  of  the  cotyloid  cavity,  and  is  lost  in  the  reddish,  fatty  tissue  situated  at  the  bottom 
of  it.  The  distribution  of  the  obturator  artery  is  much  more  limited  than  that  of  the  ob- 
turator nerve. 

The  Ilio-lumbar  Artery. 

The  ilio-lumbar  artery  (A)  arises  from  the  back  of  the  internal  iliac,  and,  tolerably  fre- 
quently, from  the  gluteal.  There  are  often  two  ilio-lumbar  arteries.  This  vessel  bears 
the  same  relation  to  the  lumbar  arteries  that  the  superior  intercostal  does  to  the  aortic 
intercostals ;  its  size  and  distribution  vary  according  to  the  presence  or  absence  of  the 
fifth  lumbar  artery. 

It  has  a  retrograde  course,  running  upward  and  backward  in  front  of  the  lumbo-sacral 
nerve,  and  behind  the  psoas  muscle,  and  soon  divides  into  two  branches  :  an  ascending 
or  lumbar,  and  a  transverse  or  iliac.  The  ascending  or  lumbar  branch  passes  vertically 
upward  along  the  bodies  of  the  lumbar  vertebrae,  hidden  by  the  psoas,  and  subdivides 
into  a  muscular  branch,  which  corresponds  to  the  abdominal  branches  of  the  lumbar  ar- 
teries, and  is  distributed  to  the  psoas  and  to  the  quadratus  lumborum  ;  and  a  spinal 
branch,  which  enters  the  vertebral  canal  by  the  foramen  between  the  fifth  lumbar  verte- 
bra and  the  sacrum,  and  is  distributed  in  the  same  manner  £is  the  other  spinal  arteries. 

*  The  cases  where  th*'  obturator  artery  arises  separately  from  the  external  iliac  are  not  unfrequeut.  The 
following  description  may  serve  as  an  example.  In  one  case,  the  obturator  artery  arose  separately  from  the 
external  iliac  artery,  at  the  distance  of  one  inch  above  the  femoral  arch,  and  above  the  origin  of  the  epigastric 
artery ;  it  went  downward  and  inward  to  reach  the  lateral  wall  of  the  pelvis,  crossed  the  obturator  nerve,  and 
entered  the  sub-pubic  canal.  In  this  subject,  the  obturator  vein  joined  also  the  external  iliac  vein.  The  same 
disposition  existed  on  both  sides. 

t  The  obturator  artery  sometimes  gives  off  the  artery  to  the  bulb  of  the  urethra.  In  a  preparation  which 
was  exhibited  by  M.  Dcnonvilliers,  now  chef  des  travaux  anatomiques,  at  the  concours  for  the  office  of  prosec- 
tor, I  have  seen  a  voluminous  branch  whicli  had  arisen  from  the  obturator  artery,  extending  all  along  the  in- 
ternal part  of  the  obturator  foramen,  cross  perpendicularly  the  posterior  surface  of  the  descending  branch  of 
the  pubis,  reach  the  bulb  transversely  by  crossing  the  internal  pudic  artery,  above  which  it  was  placed.  This 
was  on  the  left  side.  On  the  right  side  the  arrangement  was  normal.  This  arrangement  is  not  as  rare  as 
might  be  believed  :  it  is  evident  that  the  ligature  of  ihe  internal  pudic  artery  would  be  useless  in  a  case  of 
this  kind,  in  arresting  a  hemorrhage  consequent  upon  nii  operation  for  the  stone. 


ANGEIOLOGT. 

The  transverse  or  iliac  branch  passes  horizontally  outward,  opposite  the  brim  of  the 
pelvis,  and  divides  into  a  superficial  branch,  which  passes  under  the  iliac  fascia,  ramifies 
upon  the  iliacus  muscle,  and  anastomoses  with  the  circumflex  iliac  artery  ;  and  into  a 
deep  and  much  larger  branch,  which  passes  between  the  ihacus  muscle  and  the  ihac 
fossa,  and  divides  into  muscular  and  periosteal  twigs.  The  principal  nutritious  artery 
of  the  ilium  is  derived  from  this  branch. 

When  there  are  two  ilio-lumbar  arteries,  the  superior  represents  the  lumbar  branch, 
and  the  inferior  the  iliac  branch :  in  such  a  case  the  latter  branch  always  arises  from  the 
gluteal  artery. 

The  Lateral  Sacral  Arteries. 

Most'commonly  there  are  two  lateral  sacral  arteries  on  each  side  ;  they  belong  rather 
to  the  interior  of  the  sacral  canal  than  to  the  cavity  of  the  pelvis,  and  form  a  continuation 
of  the  spinal  branches  of  the  lumbar  arteries ;  they  almost  as  frequently  arise  from  the 
gluteal  as  from  the  internal  iliac ;  sometimes  they  are  derived  from  the  sciatic  or  the 
Sio-lumbar  arteries. 

The  superior  lateral  sacral  is  generally  of  considerable  size.  It  passes  almost  horizon- 
tally inward,  and  after  having  given  off  some  small  transverse  branches,  which  anasto- 
mose with  the  middle  sacral,  enters  the  first  anterior  sacral  foramen,  and  divides  into 
two  branches  :  one  intended  for  the  nerves  and  their  coverings,  and  another  which  emer- 
ges from  the  sacral  canal  by  the  corresponding  posterior  sacral  foramen,  and  is  distribu- 
ted to  the  spinal  muscles  and  to  the  skin. 

The  inferior  lateral  sacral  (Ji,fig.  212)  is  situated  at  first  under  the  digitations  of  the 
pyriformis  muscle,  afterward  passes  in  front  of  that  muscle,  and  is  directed  inward  and 
downward  on  the  inner  side  of  the  sacral  foramina,  and  along  the  borders  of  the  coccyx, 
where  it  anastomoses  with  the  middle  sacral.  In  this  course  it  gives  off  a  series  of  very 
small  internal  branches,  which  correspond  to  the  several  sacral  vertebrae,  and  anastomose 
with  the  middle  sacral ;  also  some  posterior  or  spinal  branches,  each  of  which  enters  the 
sacral  canal  through  the  corresponding  sacral  foramen,  and  subdivides  into  two  small 
branches  :  one  intended  for  the  nerves  and  their  coverings,  while  the  other  emerges  from 
the  sacral  canal  by  the  corresponding  posterior  sacral  foramen,  and  is  distributed  to  the 
muscles  and  the  skin.  "When  the  superior  lateral  sacral  is  small,  the  posterior  or  spinal 
branch  of  the  inferior  lateral  sacral  is  very  large.  The  inferior  lateral  sacral  artery  often 
terminates  by  a  spinal  branch,  which  enters  at  the  lowest  anterior  sacral  foramen. 

The  Gluteal  Artery. 

The  gluteal  artery  (rn,fig.  212),  called  also  the  posterior  iliac,  is  the  largest  branch  of 
the  internal  iliac,  of  which  it  might  be  considered  the  continuation.  It  might  be  called 
superior  gluteal,  in  contradistinction  to  the  sciatic,  which  is,  in  reality,  an  inferior  gluteal. 
It  passes  downward  and  backward  between  the  lumbosacral  nerve  and  the  first  sacral 
nerve,  escapes  from  the  pelvis  at  the  upper  part  of  the  great  sacro-sciatic  notch,  above 
the  pyriformis  muscle  {m,fig.  45),  is  reflected  upon  the  border  of  that  notch,  and  divides 
into  a  superficial  and  a  deep  branch.  The  superficial  branch  (a)  passes  horizontally  for- 
ward, between  the  glutaeus  maximus  and  medius,  and  is  almost  entirely  distributed  to  the 
upper  part  of  the  first-named  muscle  and  to  the  adjacent  part  of  the  skin ;  the  deep  branch 
{b)  passes  between  the  glutaeus  medius  and  minimus,  and  subdivides  into  two  branches  ; 
the  lower  of  these  runs  horizontally,  and  may  be  traced  as  far  as  the  anterior  border  of 
the  glutaeus  medius,  while  the  other  very  nearly  follows  the  curve  described  by  the  origin 
of  the  glutaeus  minimus.  This  branch  gives  off  some  muscular  arteries,  several  nutri- 
tious arteries  to  the  bone,  and  severtd  articular  branches. 

One  circumstance  regarding  the  gluteal  artery  worthy  of  remark  is  the  fact  that,  in 
common  with  all  arteries  of  a  certain  size,  it  is  liable  to  aneurism,  and  that  for  the  cure 
of  this  aneurism  (which  has  always  been  the  result  of  external  violence),  the  common 
iliac  artery  has  in  two  cases  been  tied  in  America,  and  the  gluteal  artery  itself  recently 
by  an  English  surgeon. 

The  Sciatic  Artery. 
The  sciatic  artery  (o,  fig.  212),  from  its  distribution,  might  be  called  the  inferior  gluteal. 
It  often  arises  by  a  common  trunk,  either  with  the  gluteal  or  with  the  internal  pudic,  be- 
hind and  internal  to  which  it  is  situated ;  it  descends  in  front  of  the  sacral  plexus  and  the 
pyriformis  muscle,  traverses  the  sacral  plexus,  emerges  from  the  pelvis  (o,  fig.  215)  be- 
tween the  pyriformis  and  the  lesser  sacro-sciatic  ligament,  accompanied  on  its  inner  side 
by  the  great  sciatic  nerve,  and  behind  by  the  internal  pudic  artery  (p).  Outside  the  pel- 
vis, the  sciatic  artery  gives  off  iniernal  or  transverse  branches,  some  of  which  pass  trans- 
versely inward  between  the  gluteus  maximus  and  the  great  sacro-sciatic  ligament,  while 
others  (c)  perforate  that  ligament,  and  ramify  in  the  internal  attachments  of  the  glutaeus 
maximus.  Several  of  these  branches  ramify  upon  the  skin  of  the  coccygeal  region  ;  its 
other  branches  are  descending,  the  largest  of  which  {d)  gains  the  deep  surface  of  the 
glutaeus  maximus,  and  enters  that  muscle  by  numerous  branches,  which  become  cuta- 


INTERNAL  PUDIC   ARTERY. 


657 


Fig.  213. 


neous  at  their  termination ;  one  and  often  two  or  three  branches  (c)  of  the  sciatic  artery 
attach  themselves  to  the  deep  surface  of  the  great  sciatic  nerve,  and  accompany  it  to  the 
lower  part  of  the  thigh.  A  great  number  of  twigs  are  given  off  from  the  several  branches 
of  the  sciatic  artery,  which  are  distributed  to  the  small  rotator  muscles,  or  to  the  origins 
of  the  muscles  attached  to  the  tuberosity  of  the  ischium,  while  others  anastomose  with 
the  circumflex  (/)  and  perforating  arteries  («)  derived  from  the  femoral.  Among  these 
anastomoses,  I  would  point  out  one  very  considerable  anastomotic  loop,  formed  behind 
the  neck  of  the  femur  by  the  sciatic  and  internal  circumflex  arteries,  and  constituting  one 
of  the  principal  communications  between  the  internal  iliac  and  femoral  arteries. 

The  hitemal  Pudic  Artery. 

The  internal  pudic  (jp,fig.  212),  the  terminal  branch  of  the  internal  iliac,  is,  practically 
speaking,  the  most  important  of  all  the  pelvic  arteries.  It  is  smaller  than  the  sciatic, 
from  which  it  is  sometimes  given  off,  either  shortly  after  the  origin  of  that  vessel,  or  as 
it  is  passing  out  from  the  pelvis.  The  internal  pudic  runs  in  a  tortuous  manner  down- 
ward, in  front  of  the  sacral  plexus  and  the  pyriformis  muscle,  parallel  to  the  sciatic  ar- 
tery (o),  which  is  behind  it ;  escapes  from  the  pelvis,  together  with  that  vessel  {p,  o,fig. 
215),  between  the  pyriformis  muscle  and  the  spine  of  the  ischium ;  is  reflected  upon 
that  process,  turning  round  it  from  behind  forward,  so  as  to  embrace  in  succession  its 
posterior,  its  external,  and  its  anterior  surfaces,  and  then  enters  the  pelvis  again  between 
the  two  sacro-sciatic  ligaments.  The  artery,  af- 
ter descending  a  short  distance,  then  becomes  as- 
cending, and  is  situated  in  the  ischio-rectal  fossa 
{a,  Jig.  213),  and  is  applied  to  the  internal  surface 
of  the  tuberosity  of  the  ischium,  or,  rather,  of  the 
obturator  internus  muscle,  with  which  it  is  kept 
in  contact  by  a  layer  of  fascia :  it  is  separated 
from  the  levator  ani  by  a  considerable  quantity  of 
fat,  and  having  reached  the  posterior  border  of  ^ 
the  transversus  perinei  muscle,  it  divides  into  an 
inferior,  superficial,  or  perineal  branch  (c),  and  a 
stiperior  or  deep  branch  (e),  w^hich  is  distributed  to 
the  penis  in  the  male  and  to  the  clitoris  in  the  fe- 
male. An  important  variety  in  the  course  of  this 
artery  has  been  pointed  out  by  Bums,  who,  in  a 
male  subject,  saw  the  trunk  of  the  internal  pudic,  instead  of  passing  out  of  the  pelvis,  run 
upon  the  sides  of  the  inferior  fundus  of  the  bladder,  perforate  the  upper  part  of  the  pros- 
tate, and  then  terminate  in  the  usual  manner. 

Collateral  Branches. — During  its  course  within  the  pelvis,  the  internal  pudic  supplies 
branches  to  the  bladder,  rectum,  vesiculae  seminales,  and  prostate  in  the  male,  and  to 
the  vagina  in  the  female  ;  it  also  rather  frequently  gives  off  the  middle  hemorrhoidal. 
As  it  turns  round  the  spine  of  the  ischium,  it  gives  some  branches  to  the  rotator  mus- 
cles of  the  thigh.  Opposite  the  internal  surface  of  the  tuberosity  of  the  ischium,  it  gives 
origin  to  one  or  more  branches,  named  the  external  or  inferior  hemorrhoidal  (b,jig.  213), 
which  run  inward  to  be  distributed  to  the  lower  end  of  the  rectum,  to  the  sphincter, 
the  levator  ani,  and  the  skin  ;  also  some  branches  which  proceed  outward,  some  to  sup- 
ply the  periosteum  of  the  tuberosity,  while  others  ramify  in  the  muscles  attached  to  that 
process  ;  lastly,  a  very  important  communicating  branch  passes  between  the  tuberosity 
of  the  ischium  and  the  great  trochanter,  and  anastomoses  with  the  sciatic  and  internal 
circumflex  arteries. 

Terminal  branches. — These  differ  in  the  two  sexes.  We  shall  first  describe  them  in 
the  male  : 

The  inferior  branch,  the  superficial  artery  of  the  perineum,  or  the  perineal  artery  (c),  is 
smaller  than  the  superior  branch  :  it  passes  forward  and  inward,  in  the  cellular  interval 
between  the  ischio-cavernosus  and  the  bulbo-cavernosus  ;  above,  i.  e.,  deeper  than  the 
superficial  fascia  of  the  perineum,  which  separates  it  from  the  skin  ;  and  below,  i.  e., 
superficial  to  the  transversus  perinei  muscle,  it  thus  reaches  the  dartos  at  the  side  of  the 
median  line,  where  it  is  named  the  artery  of  the  septum,  and  is  distributed  to  the  scrotum 
and  the  skin  of  the  penis. 

During  its  course  the  superficial  perineal  artery  gives  internal  and  external  branches. 
Some  of  the  internal  branches  run  along  the  posterior  border  of  the  transversus  perinei 
muscle,  and  are  sometimes  so  large  as  to  bleed  very  profusely  when  they  are  divided  in 
the  operation  of  lithotomy  ;  from  its  situation,  one  of  them  is  named  the  transverse  ar- 
tery of  the  perineum  (d). 

The  deep  superior  or  deep  branch  (e),  or  the  artery  of  the  penis  (in  the  male),  is  the  con- 
tinuation of  the  trunk  of  the  internal  pudic,  both  in  regard  to  size  and  direction  :  it  runs 
along  the  ascending  ramus  of  the  ischium,  between  the  layers  of  the  triangular  ligament ; 
above,  i.  e.,  deeper  than  the  transverse  muscle,  which  it  sometimes  perforates,  also  above 
the  ischio-cavernosus  and  the  corresponding  crus  of  the  corpus  cavernosum  ;  and  oppo- 


ANGEIOLOGY. 

site  the  point  at  which  the  two  crura  unite,  it  subdivides  into  two  branches,  viz.,  the 
dorsal  artery  of  the  penis  (g)  and  the  artery  of  the  corpus  cavernosum  Qi). 

During  its  course,  the  artery  of  the  penis  gives  off  a  very  important  collateral  branch, 
named  the  artery  of  the  bulb  (/),  which  is  as  large  as  the  superficial  perineal  artery,  is 
sometimes  double,  and  generally  arises  near  the  bulb,  passes  transversely  inward,  above 
the  middle  perineal  fascia  or  triangular  ligament,  or,  rather,  in  the  substance  of  that 
ligament,  and  is  distributed  to  the  bulb  of  the  urethra  and  to  the  spongy  portion  of  this 
canal.* 

The  dorsal  artery  of  the  penis  (g)  is  sometimes  the  only  terminal  branch  of  the  internal 
pudic,  and  then  a  very  delicate  twig  supplies  the  place  of  the  artery  of  the  corpus  cav- 
ernosum, which,  in  this  case,  is  supplied  from  another  source.  This  artery  reaches  the 
dorsal  surface  of  the  penis  by  passing  between  the  symphysis  pubis  and  the  crura  of  the 
corpus  cavernosum,  and  perforating  the  suspensory  ligament  of  the  penis,  and  then  runs 
in  a  very  tortuous  manner  along,  beneath  the  skin,  upon  the  dorsal  aspect  of  that  organ, 
on  one  side  of  the  median  line,  being  retained  in  its  position  by  a  layer  of  fibrous  mem- 
brane :  it  terminates  by  ramifying  in  the  prepuce  and  in  the  glans,  around  the  base  of 
which  it  forms  a  corona.  I  have  seen  the  dorsal  artery  of  the  penis  given  off  by  one  of 
the  external  pubic  arteries,  from  which  it  arose  immediately  above  the  entrance  of  the 
saphenous  vein  into  the  femoral ;  it  then  formed  a  curve  in  the  groin,  with  its  concav- 
ity directed  downward,  and  passed  upon  the  sides  of  the  dorsal  surface  of  the  penis  ;  in 
another  instance,  the  dorsal  artery  of  the  penis  was  derived  from  the  obturator,  or,  rath- 
er, it  had  two  roots  :  a  very  small  one,  which  had  the  usual  origin,  and  a  large  one, 
which  arose  from  the  obturator  and  passed  under  the  symphysis.  The  right  and  left 
dorsal  arteries  of  the  penis  sometimes  anastomose  by  a  transverse  branch,  like  the  an- 
terior cerebral  arteries. 

The  artery  of  the  corpus  cavernosum  (h)  is  also  sometimes  the  only  terminal  branch  of 
the  internal  pudic  artery,  the  dorsal  artery  of  the  penis,  in  such  cases,  being  derived  from 
some  other  source.  I  have  seen  the  cavernous  artery  arise  from  the  obturator.  In  all 
cases  it  enters  the  corpus  cavernosum  by  the  corresponding  crus,  runs  along  its  median 
septum,  and  ramifies  in  its  areolar  structure. 

I  have  seen  the  dorsal  arteries  of  the  penis  and  the  cavernous  artery  arise  by  a  com- 
mon trunk  from  the  hypogastric  ;  this  trunk  passed  directly  from  behind  forward  to  be 
divided  immediately.  The  same  disposition  existed  on  both  sides.  The  internal  pudic 
artery  gave  off  a  small  cavernous  artery. 

In  the  female,  the  terminal  branches  of  the  internal  pudic  are  arranged  as  follows  : 
the  inferior  or  superficial  perineal  branch  is  larger  than  the  superior,  and  might  be  named 
the  artery  of  the  labia  majora,  to  which  it  is  distributed  ;  the  superior  or  deep  branch,  or  the 
artery  of  the  clitoris,  runs  along  in  contact  with  the  tuberosity  of  the  ischium,  and  then 
with  its  ascending  ramus,  and  having  given  off  a  branch,  which  runs  inward  to  the  bulb 
of  the  vagina,  terminates  in  the  dorsal  artery  and  cavernous  artery  of  the  clitoris,  these  ves- 
sels being  very  small  in  consequence  of  the  diminutive  size  of  that  organ. 

Summary  of  the  Distribution  of  the  Internal  Iliac  Jlrtery. 

The  internal  iliac  artery,  which  is  so  deeply  situated  as  to  be  inaccessible  to  the  sur- 
geon, sends  branches  to  all  the  organs  contained  in  the  cavity  of  the  pelvis ;  to  the  bony 
parietes  of  the  pelvis  and  the  sacral  canal ;  to  the  muscles  which  line  the  pelvis  within 
and  cover  it  without ;  and  to  the  skin  and  the  external  genital  organs. 

Its  several  branches  may  be  divided  into  parietal  and  visceral.  The  visceral  branches 
are  the  vesical,  middle  hemorrhoidal,  vaginal,  and  uterine  arteries,  and  the  deep  branch 
of  the  internal  pudic.  The  sympathy  existing  between  all  the  organs  to  which  the  above- 
named  vessels  are  distributed,  depends  less  upon  those  vessels  having  a  common  source 
than  upon  the  community  of  origin  of  the  several  nerves  which  those  vessels  serve  to 
support. 

The  parietal  branches  are  the  ilio-lumbar  and  lateral  sacral  arteries,  which,  with  the^ 
middle  sacral,  continue  the  series  of  intercostal  and  lumbar  arteries  into  the  sacral  re-* 
gion,  and  supply  the  sacrum,  the  spinal  nerves  and  their  coverings,  and  also  the  muscles 
of  the  vertebral  grooves  and  the  skin  of  the  sacral  region ;  the  glutaeal  and  the  sciatic  ar- 
teries intended  for  the  muscles  of  the  glutaeal  region ;  the  superficial  branch  of  the  internal 
pudic  artery,  which  supplies  the  perineum  ;  and,  lastly,  the  obturator  artery,  which  forms 
an  arterial  circle  around  the  obturator  foramen,  and  supplies  the  obturator  muscles. 

Several  branches  of  the  internal  iliac  artery  establish  anastomoses  between  that  ves- 
sel and  the  femoral  artery ;  these  are  more  especially  the  sciatic,  the  internal  pudic,  the 
gluteal,  and  the  obturator  arteries. 

Artery  of  the  Lower  Extremity,  or  Crural  Trunk. 
The  arterial  trunk  of  the  lower  extremity,  or  the  crural  trunk  (Chaussier),  corresponds 

*  The  artery  of  the  bulb,  after  having  traversed  the  bulb,  is  directed  from  behind  forward  in  the  substance 
of  the  spongy  portion  of  the  urethra,  and  may  be  followed  up  to  about  its  middle  part.  When  the  artery  of  ths 
bulb  comes  from  the  obturator  artery,  the  inferior  pudic  sends  a  rudimentary  branch  to  the  bulb.  It  is  the 
pudic  artery  which  supplies  Cowper's  glands. 


THE    EXTERNAL   ILIAC   ARTERY.  559 

With  the  brachial  trunk  of  the  upper  extremity.  This  vessel,  which  is  the  direct  con- 
tinuation of  the  common  iliac  artery,  passes  downward  and  outward,  emerges  from  the 
pelvis  beneath  the  crural  arch,  and  thus  reaches  the  anterior  region  of  the  thigh.  Op- 
posite the  junction  of  the  two  upper  thirds  with  the  lower  third  of  the  femur,  it  traverses 
the  fibrous  canal  formed  for  it  by  the  tendon  of  the  great  adductor  muscle,  and  thus 
gains  the  popliteal  space,  at  the  lower  part  of  which  it  terminates  by  dividing  into  two 
branches.  The  numerous  and  important  relations  of  this  vessel,  and  the  great  number 
of  branches  arising  from  it,  have  led  to  its  division  by  anatomists  into  three  portions, 
which  are  named  the  external  iliac  artery,  the  femoral  or  crural  artery,  and  the  popliteal  ar- 
tery. The  two  terminal  branches  are  the  anterior  tibial,  which,  in  the  foot,  is  termed  the 
dorsal  artery  of  the  foot,  and  the  tibio-peroneal  trunk,  which  divides  into  the  peroneal  and 
posterior  tibial  arteries,  the  latter  of  which  terminates  in  the  sole  of  the  foot  by  subdivi- 
ding into  the  internal  and  external  plantar  arteries. 

The  External  Iliac  Arteky. 

The  external  iliac  artery  (r,  figs.  199,  212),  the  outer  of  the  two  branches  into  which  the 
common  iliac  divides,  is  analogous  to  the  subclavian  artery  in  the  upper  extremity.  It 
extends  from  the  highest  part  of  the  sacro-iliac  symphysis  to  the  lower  border  of  the  fem- 
oral arch  or  Poupart's  ligament,  below  which  it  takes  the  name  of  femoral  artery.  It  is 
directed  obliquely  downward  and  outward,  in  a  line  extending  from  the  sacro-iliac  sym- 
physis to  the  crural  ring,  and  is  almost  always  straight,  but  sometimes  tortuous.  It  has 
the  following  relations  :  in  front  and  on  the  inner  side,  it  is  covered  by  the  peritoneum, 
which  is  very  loosely  attached  to  it :  an  important  fact,  which  enables  the  surgeon  to 
separate  that  membrane  from  it  in  applying  a  ligature  to  the  vessel ;  on  the  outer  side,  it 
rests  against  the  psoas  muscle,  from  which  it  is  separated  by  the  iUac  fascia ;  behind,  the 
artery  of  the  right  side  is  in  relation  with  the  corresponding  external  iliac  vein,  which 
is  placed  to  its  inner  side  below ;  on  the  left  side  the  vein  is  below,  and  on  the  inner  side 
of  the  artery ;  lastly,  the  genito-crural  nerve,  just  as  it  is  about  to  enter  the  inguinal  ca- 
nal, crosses  in  front  of  this  artery,  and  so  also  do  the  spermatic  vessels  ;  the  circumflex 
iliac  vein  crosses  it  at  right  angles  behind  the  femoral  arch,  in  order  to  terminate  in  the 
external  iliac  vein  ;  besides  this,  it  is  covered  immediately  behind  the  arch  by  several 
lymphatic  glands  ;  higher  up,  the  ureter  crosses  obliquely  in  front  of  it,  and  the  artery  of 
the  right  side  is  covered  by  the  termination  of  the  ileum,  and  that  of  the  left  side  by  the 
sigmoid  flexure  of  the  colon. 

Collateral  Branches. — The  external  iliac  artery  furnishes  no  branches,  excepting  at  its 
lower  part,  near  the  femoral  arch,  where  it  gives  off  the  epigastric  and  circumflex  iliac 
arteries. 

The  Epigastric  Artery. 

The  epigastric  artery  is,  practically  speaking,  one  of  the  most  important  to  be  well  un- 
derstood, on  account  of  its  relations  with  the  crural  ring  and  inguinal  canal,  that  is  to 
say,  with  the  parts  through  which  the  viscera  generally  descend  in  herniae. 

This  artery  (v,figs.  199,  212)  arises  from  the  inner  side  of  the  external  iliac,  two  or 
three  lines  above  the  femoral  arch.  Its  origin,  however,  is  subject  to  some  varieties  : 
sometimes  it  takes  place  half  an  inch,  one,  or  even  two  inches  above  the  crural  arch  :  an 
important  fact  in  reference  to  the  application  of  a  ligature  to  the  external  iliac.  Hessel- 
bach  and  several  others  state  that  they  have  seen  the  epigastric  arise  from  the  obtura- 
tor artery  ;  but  their  descriptions  appear  to  me  to  prove  nothing  more  than  that  the  epi- 
gastric and  obturator  arteries  may  arise  by  a  common  trunk.  It  is  worthy  of  remark 
that  the  obturator  is  often  observed  to  arise  from  the  epigastric,  while  there  is,  perhaps, 
no  example  of  the  epigastric  being  derived  from  the  obturator.  The  obturator  so  fre- 
quently arises  by  a  common  trunk  with  the  epigastric,*  that  many  anatomists  have 
thought  that  the  obturator  is  derived  from  the  epigastric  more  frequently  than  from  the 
internal  iUac  artery.  In  250  subjects  examined  for  this  purpose  by  M.  Jules  Cloquet, 
the  obturator  arose  150  times  from  the  epigastric  on  both  sides,  28  times  on  one  side 
only,  and  6  times  from  the  femoral  artery.  Althoug:h  it  is  a  very  common  occurrence  to 
have  the  obturator  artery  arising  from  the  epigastric,  it  is  very  rare  to  find  the  epigas- 
tric taking  its  origin  from  the  obturator.  This  anatomical  variety  has  only  been  report- 
ed as  having  occurred  in  two  cases.  One  can  easily  understand  how  dangerous  it  would 
be  to  operate  for  the  relief  of  a  strangulated  hernia  in  such  a  case. 

The  epigastric  artery,  whether  it  gives  off  the  obturator  or  not,  passes  transversely 
or  obliquely  inward,  and,  having  arrived  below  the  spermatic  cord  in  the  male,  and  the 
round  ligament  in  the  female,  is  reflected  upward,  so  as  to  describe  a  curve  having  its 
concavity  directed  upward,  and  corresponding  to  the  loop  formed  by  the  spermatic  cord 
o'  round  ligament,  the  concavity  of  which  is  directed  downward.  When  the  cbturator 
arises  by  a  common  trunk  with  the  epigastric,  it  is  given  oflf  at  the  point  where  the  lat- 
ter is  reflected  upward,  and  from  the  convexity  of  the  curve.     After  being  reflected,  the 

*  It  would  be  very  difficult  to  explain  why  the  epigastric  and  the  obturator  arteries  are  so  intimately  cott 
nected  at  their  origins. 


9Bfk  ANGEI0L06Y. 

epigastric  artery  ascends  obliquely  inward,  soon  reaches  the  outer  border,  and  next  the 
posterior  surface  of  the  rectus  abdominis  muscle,  and  then  passes  vertically  upward. 
Having  reached  the  umbilicus,  it  penetrates  into  the  substance  of  the  rectus,  and  termi- 
nates by  anastomosing  with  the  internal  mammary  artery. 

Relations. — The  relations  of  the  transverse,  oblique,  and  vertical  portions  of  the  epi- 
gastric artery  should  be  examined  separately.  The  transverse  portion  varies  in  length 
in  different  subjects ;  sometimes  it  is  almost  entirely  wanting,  the  artery  running  im- 
mediately upward  ;  at  other  times  it  is  an  inch  and  a  half  in  length.  This  difference  in 
length,  which  is  of  no  consequence  when  the  obturator  artery  arises  from  the  internal 
iliac,  becomes  highly  important  when  that  vessel  is  given  off  from  the  epigastric* 

This  transverse  portion  of  the  artery  is  directed  obliquely  downward,  when  the  ej  - 
gastric  arises  at  a  certain  distance  above  the  ring. 

The  oblique  portion  of  the  epigastric  artery  forms  the  outer  side  of  a  triangle,  the  in- 
ner side  of  which  is  formed  by  the  outer  border  of  the  rectus  abdominis  muscle,  and  the 
base  by  the  crural  arch  :  the  epigastric  constitutes  the  true  boundary  between  the  inter- 
nal inguinal  fossa,  which  comprises  all  the  triangular  space  situated  on  the  inner  side 
of  the  vessel,  and  the  external  inguinal  fossa,  which  comprises  the  space  upon  its  outer 
side.  The  abdominal  orifice  of  the  inguinal  canal  is  situated  in  the  external  inguinal 
fossa,  and,  consequently,  to  the  outer  side  of  the  epigastric  artery.  Those  inguinal  her- 
nise  which  pass  through  the  internal  fossa  are  called  internal  or  direct  inguinal  herniae  ; 
those  which  take  place  on  the  outer  side  of  the  artery  are  called  external  or  oblique  in- 
guinal. 

In  its  horizontal  and  oblique  portions,  the  epigastric  artery  is  placed  between  the  per- 
itoneum and  the  fascia  transversalis.  I  should  observe  that  the  spermatic  cord  in  the 
male,  and  the  round  ligament  in  the  female,  do  not  cross  the  epigastric  artery  precisely 
in  the  situation  of  the  loop  which  this  vessel  describes,  but  a  little  above  it.  The  axis 
of  the  inguinal  canal  being  directed  obliquely  downward  and  inward,  intersects  at  right 
angles  the  oblique  portion  of  the  artery,  which  slopes  in  the  opposite  direction. 

In  its  vertical  portion,  the  epigastric  artery  is  situated  between  the  rectus  and  the  pos- 
terior wall  of  the  sheath  of  that  muscle  until  near  the  umbilicus,  where  it  dips  into  the 
fleshy  fibres. 

Collateral  Branches. — Near  its  origin,  or,  rather,  opposite  the  bend  which  it  takes,  the 
epigastric  artery  sometimes  gives  off  the  internal  circumflex,  which,  as  we  shall  here- 
after see,  generally  arises  from  the  deep  femoral.  It  always  gives  off  the  following 
branches  :  a  cremasteric  branch  {I,  Jig-  214),  which  enters  the  inguinal  canal,  runs  along 
the  fibrous  sheath  of  the  cord  in  the  male,  and  the  round  ligament  in  the  female,  and 
passes  in  the  one  to  the  coverings  of  the  testicles,  and  in  the  other  to  the  labia  majora ; 
a  second  branch,  which  runs  along  the  inner  portion  of  the  femoral  arch,  and  anasto- 
moses with  its  fellow  of  the  opposite  side  behind  the  symphysis  ;  and,  lastly,  a  branch 
which  crosses  the  horizontal  ramus  of  the  pubes  at  right  angles,  and  anastomoses  with 
the  obturator.  I  have  already  stated  that  this  small  branch  may  be  regarded  as  forming 
the  trunk  of  the  obturator  when  that  artery  arises  from  the  epigastric.  In  its  oblique 
and  vertical  portions,  the  epigastric  gives  off  a  number  of  internal  and  external  ascending 
branches,  which  pass  very  obliquely  through  the  rectus  abdominis,  partially  supply  that 
muscle,  and  then  pierce  the  anterior  wall  of  its  sheath,  the  internal  branches  near  the 
linea  alba,  and  the  external  branches  near  the  outer  border  of  the  sheath,  to  ramify  upon 
the  skin.  These  branches  anastomose  with  the  internal  mammary  and  with  the  lumbar 
arteries. 

The  anastomosis  of  the  epigastric  with  the  internal  mammary  takes  place  only  in  the 
substance  of  the  rectus,  and  by  very  small  vessels. 

The  Circumflex  Iliac  Artery. 

The  circumflex  or  posterior  iliac  artery  {x,  figs.  199,  212),  smaller  than  the  epigastric, 
arises  from  the  outer  part  of  the  external  iliac,  either  opposite  the  epigastric  or  a  little 
below  it.  It  sometimes  arises  from  the  upper  part  of  the  femoral  artery  :  it  is  generally 
single,  but  occasionally  double,  which  may  be  regarded  as  resulting  from  a  premature 
division  of  the  vessel. 

It  passes  obUquely  upward  and  outward,  behind  the  crural  arch,  with  which  it  is  held 
in  contact  by  a  fibrous  layer  interposed  between  it  and  the  peritoneum.  Opposite  the 
anterior  superior  spinous  process  of  the  ihum  it  divides  into  two  branches :  one  is  an 
ascending  or  abdominal  branch,  which  passes  upward,  in  the  substance  of  the  abdominal 
parietes,  between  the  transversalis  and  obUquus  intemus  muscles,  parallel  with  the  ep- 
igastric artery,  and  terminates  by  anastomosing  with  the  inferior  intercostal  and  the 
lumbar  arteries  ;  the  other  is  the  circumflex  ihac  artery  properly  so  called,  which  is  the 

*  [If  the  obturator  arises  high  up  from  the  epigastric,  it  describes,  before  it  euters  the  pelvis,  a  semicircle 
extending  along  the  upper,  and  then  the  inner  border  of  the  crural  ring ;  and,  consequently,  has  such  rela- 
tions with  the  neck  of  the  sac  in  femoral  hernia,  that  render  it  almost  impossible  to  avoid  wounding  the  ar- 
tery in  dividing  the  stricture  upward  and  inward.  But  if,  as  is  much  more  frequently  the  case,  it  arises  from 
near  the  commencement  of  the  epigastric,  or  by  a  common  trunk  with  it,  it  then  descends  at  once  into  the  pel 
vis  obliquely  along  the  outer  border  of  the  crural  ring,  and  will  have  the  same  relation  with  a  femoral  henua.J 


THE    FEMORAL    ARTERY. 


56« 


continuation  of  the  vessel  in  direction  and  sometimes  in  size ;  it  runs  along  the  crest 
of  the  ilium,  is  at  first  sub-aponeurotic,  or,  rather,  is  contained  between  two  layers  of 
fascia  in  the  cellular  interval  separating  the  transversalis  from  the  obliquus  internus, 
and  terminates  by  anastomosing  with  the  fourth  lumbar  artery  upon  the  crest  of  the  ilium. 
During  its  course,  the  circumflex  iliac  artery  gives  off  ascending  branches,  which  ram- 
ify in  the  muscles  and  integuments  of  the  abdominal  parietes ;  and  descending  branches, 
which  ramify  in  the  iliac  fossa,  and  anastomose  with  the  iliac  branches  of  the  obturator 
artery. 

The  Femoral  Artery. 

The  femoral  or  crurcu  artery  (a  a',  fig.  214)  is  that  portion  of  the  artery  of  the  Icn'er  ex- 
tremity which  intervenes  between  the  external  iliac  and  pop-  Fig.  214. 
liteal  arteries  ;  it  is  bounded  above  by  the  crural  arch,  and 
below  by  the  junction  of  the  two  upper  thirds  with  the  lower 
third  of  the  thigh,  or,  rather,  by  the  place  where  the  artery 
passes  through  the  tendinous  ring  formed  by  the  adductor 
magnus. 

It  has  been  proposed  to  take  as  the  lower  boundary  of  the 
femoral  artery  the  origin  of  the  deep  femoral  or  profunda  ar- 
tery, which  has  been  correctly  regarded  as  a  terminal  branch 
resulting  from  the  bifurcation  of  the  femoral  artery,  rather 
than  as  a  collateral  branch.  According  to  this  view,  which 
has  not  been  generally  adopted,  the  femoral  would  not  be  more 
than  from  an  inch  and  a  half  to  two  inches  in  length,  and 
would  divide  into  a  superficial  and  deep  femoral. 

The  femoral  artery  is  directed  vertically,  and  somewhat 
obliquely  backward,  so  that  it  forms  a  slight  angle  with  the 
external  iliac,  on  account  of  the  oblique  inclination  forward 
of  that  vessel ;  and,  farther,  although  it  is  in  front  of  the  fe- 
mur above,  it  is  placed  on  the  inner  side  of  it  below,  prepara- 
tory to  becoming  posterior  to  it  in  the  popliteal  space.  A  line 
drawn  from  the  middle  of  the  space  between  the  anterior  su- 
perior spinous  process  of  the  ilium  and  the  symphysis  pubis, 
down  to  the  inner  side  of  the  femur,  below  the  middle  of  that 
bone,  would  exactly  represent  its  direction.  The  direction 
of  the  femoral  artery,  in  respect  to  the  femur,  is  such,  that 
immediately  below  the  femoral  arch  it  is  situated  over  the 
point  of  junction  of  the  inner  with  the  two  outer  thirds  of  the 
head  of  that  bone,  while  lower  down  it  is  in  relation  with  the 
inner  aspect  of  the  bone ;  the  artery,  therefore,  forms  an  acute 
angle,  opening  upward,  with  the  shaft  of  the  femur,  and  there 
is  an  interval  of  an  inch  to  eighteen  lines  between  the  vessel 
and  the  upper  part  of  the  bone,  into  which  instruments  may 
be  passed  without  wounding  the  artery.  Advantage  is  taken 
of  this  fact  in  disarticulating  the  head  of  the  femur  in  amputation  at  the  hip-joint. 

The  femoral  artery,  which  is  slightly  tortuous  when  the  thigh  is  flexed  upon  the  pelvis, 
becomes  straight  when  the  limb  is  extended,  and  it  is  much  stretched  during  forcible  ex- 
tension. 

Relations. — In  front,  the  femoral  artery  lies  beneath  the  fascia  in  the  triangular  space 
which  is  bounded  on  the  inside  by  the  inner  border  of  the  adductor  longus  ;  on  the  out- 
side, by  the  sartorius  ;  and  above,  by  the  femoral  arch.  Lower  down,  the  sartorius  is 
placed  between  the  fascia  and  the  artery,  which  is  in  relation,  first,  with  the  inner  bor- 
der, then  with  the  posterior  surface,  lastly,  with  the  outer  border  of  that  muscle  :  besides 
the  fascia,  a  number  of  lymphatic  glands  lie  between  the  upper  part  of  the  artery  and 
the  skin.  Enlargement  of  one  or  more  of  these  glands  has  been  mistaken  for  an  aneu- 
rism, and  an  aneurism  for  an  enlarged  gland.  From  these  relations  of  the  front  of  the 
femoral  artery,  it  foUoivs  that  its  anterior  aspect  may  be  exposed  in  the  whole  of  its  ex- 
tent, but  that  it  is  more  superficial  in  the  neighbourhood  of  the  crural  arch. 

Behind,  the  femoral  artery  rests,  first,  upon  the  body  of  the  pubes,  or  the  ilio-pectineal 
eminence,  with  which  it  is  in  immediate  contact  in  emaciated  subjects,  but  from  which 
it  is  generally  separated  by  the  contiguous  borders  of  the  psoas-iliac  and  the  pectineus 
muscles.  The  iliac  fascia  separates  it  from  the  psoas-iliac  muscle,  so  that,  in  cases  of 
simple  psoas  abscess,  or  congestive  abscess  from  caries  of  the  lumbar  vertebrae,  the  fem- 
oral artery  is  situated  in  front  of  the  sac  of  the  abscess.  The  femoral  artery  is  also  in 
relation,  behind,  with  the  head  of  the  femur ;  lower  down,  with  the  pectineus,  and  then 
with  the  adductor  longus.  It  follows,  therefore,  that  the  femoral  artery  may  be  very 
eflfectually  compressed  at  its  upper  part,  since  it  is  superficially  situated,  and  rests  upon 
hard  parts. 

On  Ike  outer  «ie,  it  is  in  relation,  first,  with  the  psoas-iliac,  then  with  the  inner  border 

4B 


562  ANGEIOLOGY. 

of  the  sartorius,  and,  lastly,  with  the  vastus  internus,  which  separates  it  from  the  inner 
surface  of  the  femur. 

In  consequence  of  this  relation  to  the  bone,  and  also  of  the  slight  thickness  of  the  sar- 
torius, which  separates  it  from  the  skin,  the  femoral  artery  may  be  compressed  against 
the  femur  from  within  outward  in  the  middle  third  of  the  thigh. 

On  its  inner  side,  it  is  in  relation  with  the  pectineus,  the  adductor  longus,  and  afterward 
with  the  outer  border  of  the  sartorius. 

Relations  of  the  Artery  with  the  Vein  and  Nerves. — The  femoral  vein  is  situated  on  the 
inner  side  of  the  artery  above,  but  it  soon  passes  behind  it,  and,  still  lower  down,  is  on 
its  outer  side.  The  crural  nerve  lies  on  the  outer  side  of  tlie  artery,  from  which  it  is 
separated  by  a  fibrous  layer  belonging  to  the  sheath  of  the  psoas  and  iliaeus.  The  artery 
and  nerve,  therefore,  have  no  immediate  relation  with  each  other ;  but  the  internal  or 
long  saphenous  nerve  soon  runs  upon  the  sheath  of  the  femoral  vessels,  and  is  situated 
on  the  outside  of  the  artery  ;  but  as  the  vessel  is  passing  through  the  tendon  of  the  ad- 
ductor magnus,  the  nerve  leaves  it,  and,  lower  down,  escapes  from  under  the  tendon  of 
the  sartorius.  The  short  saphenous  nerve,  or  nerve  of  the  internal  vastus,  is  in  relation 
with  the  outer  side  of  the  artery  for  a  short  distance,  and  the  vessel  is  also  crossed  by 
another  small  nerve. 

The  Sheath  of  the  Femoral  Vessels. — ^The  femoral  artery  and  vein  are  enclosed  in  a  proper 
fibrous  sheath,  which  is  constructed,  as  it  were,  in  the  midst  of  the  muscles  of  the  thigh 
(see  Aponeurology).  It  is,  therefore,  necessary  to  open  this  sheath,  and  not  that  of 
any  of  the  surrounding  muscles,  in  order  to  expose  the  artery. 

Anatomical  Varieties. — Independently  of  the  very  frequent  and  remarkable  anatomical 
varieties  in  the  origin  of  the  deep  femoral  artery,  which  is  often  given  off  opposite,  and 
sometimes  above  the  femoral  arch — varieties  to  which  I  shall  immediately  refer  in  speak- 
ing of  the  deep  femoral  artery — ^the  common  femoral  artery  itself  offers  some  varieties 
which  are  not  less  interesting.  The  most  important  is  the  following,  found  in  a  prep- 
aration deposited  by  M.  Manec  in  the  museum  of  Clamard :  In  this  preparation,  the  fem- 
oral artery  presents  behind  the  Fallopian  ligament  a  caliber  which  is  not  larger  than  that 
of  the  radial  artery,  and  is  lost  in  the  anterior  muscles  of  the  thigh.  The  ischiatic  ar- 
tery, which  is  a  branch  of  the  hypogastric,  presents,  on  the  contrary,  the  caliber  of  the 
femoral  artery,  descends  backward  along  the  great  sciatic  nerve,  and  is  continuous  with 
the  popliteal  artery.  During  its  course  along  the  thigh,  the  ischiatic  artery  gives  off  the 
muscular  branches  which  generally  come  from  the  deep  femoral  artery. 

Collateral  Branches. — The  collateral  branches  of  the  femoral  are,  the  superficial  epigas- 
tric artery,  the  two  external  pudic  arteries,  a  great  number  of  muscular  branches,  and  the 
deep  femoral  artery. 

The  Superficial  Epigastric  Artery. 
The  superficial  epigastric  or  sub-cutaneous  abdominal  artery  (cut  across  at  b,fig.  214) 
is  a  very  small,  but  remarkably  constant  branch,  which  arises  from  the  front  of  the 
femoral,  and  sometimes  from  the  external  pudic,  immediately  below  the  crural  arch, 
passes  vertically  upward,  between  the  integuments  and  the  superficial  fascia,  gives  some 
branches  to  the  inguinal  lymphatic  glands,  and  terminates  in  the  skin,  near  the  umbili- 
cus (arteria  ad  cutem  abdominis,  Haller). 

The  External  Pudic  Arteries. 

The  external  pudic  or  genital  arteries,  also  named  scrotal  in  the  male,  and  vulvar  in  the 
female,  arise  from  the  inner  side  of  the  femoral :  they  are  two  in  number  (c  c,  fig.  214), 
and  are  named  the  superior  or  sub-cutaneous,  and  the  inferior  or  sub-aponeurotic. 

The  superior  or  sub-cutaneous  arises  immediately  below  the  crural  arch,  passes  trans 
versely  inward  in  the  sub-cutaneous  cellular  tissue,  and  divides  into  two  branches :  a 
superior,  which  passes  to  the  pubic  eminence,  and  an  inferior,  which  is  distributed  to 
the  skin  of  the  penis  and  scrotum  in  the  male,  and  to  the  corresponding  external  labium 
in  the  female.     I  have  seen  the  dorsal  artery  of  the  penis  arise  from  this  vessel. 

The  inferior  or  sub-aponeurotic  branch  arises  a  little  below  the  preceding,  and  some- 
times even  from  the  deep  femoral ;  it  passes  transversely  inward,  crosses  the  femoral 
vein  at  right  angles  immediately  below  the  point  where  it  is  joined  by  the  saphenous 
vein,  so  that  this  artery  is  generally  received  in  the  loop  described  by  the  upper  end  of 
the  saphenous  vein  :  it  soon  perforates  the  fascia  and  becomes  sub-cutaneous,  and  then 
ramifies  in  the  scrotum  in  the  male,  and  in  the  external  labium  in  the  female.  The 
anastomoses  of  the  superior  and  inferior  external  pudics,  both  with  each  other  and  with 
those  of  the  opposite  side,  are  so  free  and  large,  that  when  one  of  them  is  cut  across,  it 
becomes  necessary  to  tie  both  of  the  cut  ends  of  the  vessel.  These  arteries  are  re- 
Tnarkable  on  account  of  their  relations  with  hernial  tumours. 

The  Muscular  Arteries. 
The  femoral  gives  off  a  great  number  of  muscular  and  cutaneous  branches,  which  have 
received  no  particulai  names.     One,  however,  is  usually  described  as  the  superficial  m 


THE  DEEP  FEMORAL  ARTERY.  563 

greax  muscular  artery,  which  frequently  arises  from  the  deep  femoral ;  it  passes  trans- 
versely between  the  sartorius  and  the  rectus  femoris,  and  immediately  divides  into  as- 
cending branches,  which  proceed  to  the  iliacus,  sartorius,  and  tensor  vaginee  femoris,  and 
into  very  large  descending  bra?iches,  some  of  which  are  distributed  to  the  rectus  fem- 
oris, passing  in  at  its  posterior  surface,  while  others  penetrate  the  vastus  internus  and 
vastus  externus.  The  last-mentioned  branches  can  be  traced  as  far  as  the  lower  part 
of  the  triceps  muscle  ;  and,  indeed,  the  great  muscular  artery  might  be  named  the  mus- 
cular artery  of  the  triceps  extensor  femoris,  which  ig,fig.  214)  may  arise  from  the  deep 
femoral  artery. 

The  Deep  Femoral  Artery. 

The  deep  femoral  artery  {profunda  femoris ;  d  d',  fig.  214.)  is  intended  to  supply  the 
muscles  and  integuments  of  the  internal  and  posterior  regions  of  the  thigh.* 

It  arises  from  the  back  of  the  femoral,  generally  about  one  and  a  half  or  two  inches 
below  the  crural  arch,  about  half  way  between  the  pubes  and  the  lesser  trochanter,  very 
rarely  below  this  point,  but  more  commonly  above  it.  Thus  the  femoral  often  divides, 
either  about  six  lines  below  the  crural  arch,  or  immediately  beneath  and  on  a  level  with 
it,  into  two  equal  and  parallel  branches,  of  which  the  external  is  the  deep  femoral,  and 
the  internal  the  femoral  properly  so  called.  I  have  seen  this  subdivision,  which  bears  a 
rather  close  analogy  to  the  bifurcation  of  the  humeral  artery  into  the  radial  and  ulnar 
in  the  axilla,  take  place  above  the  crural  arch,  that  is  to  say,  in  the  external  iliac  artery. 
Immediately  after  its  origin,  the  deep  femoral  passes  backward  and  outward,  and  then 
vertically  downward,  gradually  approaching  the  femur ;  it  is  situated  deeply  behind  the 
femoral  artery,  but  is  separated  from  it  by  the  femoral  and  deep  femoral  veins  ;  it  runs 
parallel  to  th'fe  femoral  artery,  in  front  of  the  pectineus,  and  on  the  outer  side  of  the  vastus 
internus  ;  having  reached  the  upper  border  of  the  long  adductor,  it  passes  behind  that 
muscle  to  arrive  between  it  and  the  short  and  great  adductors,  perforates  the  latter  mus- 
cle a  little  below  the  tendinous  opening  for  the  proper  femoral  artery,  and  terminates  by 
ramifying  in  the  biceps  and  semi-membranosus.  Sometimes  the  deep  femoral  perforates 
the  adductor  magnus  almost  immediately,  and  at  once  becomes  posterior  to  it. 

Varieties  of  Origin. — In  the  history  of  the  deep  femoral  artery,  the  varieties  in  its  origin 
are  most  important,  considered  in  a  surgical  point  of  view. 

The  common  femoral  artery  is  very  often  divided  prematurely  into  two  equal  and 
parallel  branches,  the  external  of  which  is  the  deep  femoral,  and  the  internal  the  true  or 
superficial  femoral  artery,  t  This  premature  division  may  take  place  at  a  distance  of 
six  lines  below  the  crural  arch,  opposite  this  arch,  or  even  beneath  it.  I  have  seen  this 
division,  which  bears  a  resemblance  to  the  high  division  of  the  humeral  artery  into  the 
radial  and  ulnar  arteries  in  the  hollow  of  the  axilla,  to  take  place  above  the  femoral  arch, 
consequently  at  the  expense  of  the  external  iliac  artery.  Bums  has  seen  this  division 
taking  place  in  the  pelvis  three  times  ;  Tiedemann,  who  has  observed  it  on  both  sides, 
thinks  that  it  is  only  met  with  in  small-sized  individuals.  In  a  case  which  Professor 
Dubreuil  has  communicated  to  me,  where  the  right  femoral  artery  was  divided  higher 
than  usual,  the  epigastric  artery,  instead  of  being  given  off  by  the  external  iliac,  came 
from  the  deep  femoral,  and  the  anterior  circumflex  iliac  artery  came  from  the  superficial 
femoral  artery. 

In  another  case  which  has  been  furnished  to  me  by  the  same  observer,  the  external 
iliac  or  femoral  artery,  in  its  passage  below  the  crural  arch,  was  divided  into  three  branch- 
es :  the  external  branch  was  the  superficial  muscular,  the  internal  branch  was  the  deep 
muscular,  which,  immediately  after  its  origin,  dipped  between  the  muscles  ;  the  middle 
branch,  which  was  of  a  larger  size  than  the  two  others,  was  the  true  femoral  artery. 
The  only  anomalies  in  this  case  were  in  the  origin  of  the  branches ;  in  their  distribution 
they  were  as  usual. 

During  its  course,  the  deep  femoral  gives  off  a  great  number  of  collateral  branches, 
which  are  soon  expended  in  the  adjacent  muscles,  and  most  of  which  are  unnamed. 
Those  that  are  named  are  the  internal  and  external  circumflex,  and  the  several  f  erf  orating 
arteries. 

The  internal  circumflex  artery  (e)  is  larger  than  the  external,  and  is  the  first  branch 
given  off  from  the  deep  femoral ;  not  unfrequently  it  arises  from  the  femoral.  I  have 
observed,  however,  that  this  only  takes  place  when  the  deep  femoral  artery  arose  a  lit- 
tle lower  down  than  usual.     In  a  case  of  this  kind,  the  origin  of  the  deep  artery  took  place 

*  It  is  the  proper  artery  of  the  thigh,  while  the  femoral  itself  may  be  regarded  as  the  artery  of  the  leg  and 
foot. 

t  This  relation  is  the  one  which  always  exists  when  the  deep  femoral  artery  arises  opposite  or  above  the 
femoral  arch  ;  the  deep  femoral  passes  down  close  by  the  external  side  of  the  superficial  femoral  ;  this  latter 
covers  the  vein :  if,  in  a  case  of  this  kind,  the  femoral  artery  were  to  be  tied,  and  the  ligature  were  applied 
only  to  one  vessel,  it  would  be  to  the  deep  artery,  which  holds  the  relations  that  generally  belong  to  the  trunk 
of  the  femoral  artery  itself. 

Tn  a  case  exhibited  at  the  Anatomical  Society  by  M.  Mercier,  the  deep  femoral,  which  arose  from  the  ante- 
rior side  of  the  common  femoral  six  lines  below  the  arch,  descended  downward  before  the  feiii  ral  vein,  which 
it  crossed  opposite  the  opening  for  the  scaphena  vein,  turned  round  this  vessel  to  become  the  c<;f\i  artery,  and 
coursed  along  as  usual.     In  this  case,  the  deep  femoral  gave  off  the  external  pudic  iirteries 


564  ANGEIOLOGY. 

more  than  two  inches  below  the  femoral  arch.  Sometimes  the  internal  circamflex  comes 
from  the  external  iliac  artery.  Whatever  may  be  its  origin,  it  almost  immediately  dips 
backward,  between  the  pectineus  and  the  neck  of  the  femur,  round  which  it  turns  in  the 
same  manner  as  the  posterior  humeral  circumflex  artery,  so  that  it  may  be  ruptured  in 
luxation  of  the  femur  inward :  it  escapes  backward  beneath  the  quadratus  femoris,  and 
terminates  by  dividing  into  ascending  branches,  and  into  internal  and  external  descend- 
ing branches. 

Opposite  the  pectineus,  it  gives  off  the  following  collateral  branches :  cae  very  re- 
markable articular  branch  ascends  along  the  capsular  ligament,  enters  the  hip-joint,  passes 
under  the  ligament  which  converts  the  cotyloid  notch  into  a  canal,  and  is  distributed  to 
the  synovial  membrane,  the  adipose  tissue,  and  the  fibrous  capsule  of  the  joint :  one  or 
more  anastomotic  branches  communicate  freely  with  the  ramifications  of  the  obturator 
artery ;  lastly,  a  great  number  of  muscular  branches,  some  of  which  are  very  small,  and 
pass  in  front  of,  while  others,  which  are  larger,  run  behind,  the  pectineus,  and  are  distrib- 
uted to  the  obturator  externus,  the  pectineus,  and  the  adductors  :  the  largest  is  intended 
for  the  adductor  magnus. 

The  terminal  branches  are  as  follows  :  Ascending  muscular  branches,  some  of  which  are 
external,  and  ramify  in  the  glutaeus  maximus,  while  others  are  internal,  and  are  dis- 
tributed to  the  ischiatic  attachments  of  the  biceps,  semi-tendinosus,  and  semi-membra- 
nosus  muscles ;  descending  muscular  branches,  which  ramify  upon  the  anterior  surface 
of  the  biceps,  semi-tendinosus,  and  semi-membranosus,  upon  the  great  sciatic  nerve, 
and  also  in  the  small  muscles  situated  between  the  pelvis  and  the  trochanter  major ; 
periosteal  branches,  of  which  some  ramify  upon  the  periosteum  of  the  trochanter,  other& 
upon  the  posterior  surface  of  the  neck  of  the  femur  ;  and,  lastly,  anastomotic  branches, 
which  pass  upon  the  obturator,  gemelli,  and  pyriformis  muscles,  and  anastomose  freely 
with  the  sciatic,  glutaeal,  internal  pudic,  and  obturator  arteries,  but  especially  with  the 
sciatic  and  the  obturator. 

It  follows,  then,  that  the  internal  circumflex  is  an  important  means  of  communication 
between  the  internal  Uiac,  and,  consequently,  the  common  iliac  and  the  femoral ;  for, 
independently  of  the  direct  anastomoses  above  mentioned,  there  are  a  great  number  of 
indirect  communications  in  the  substance  of  the  muscles  and  upon  the  periosteum. 

The  external  or  anterior  circumflex  (/),  smaller  than  the  internal,  sometimes  arises  di- 
rectly from  the  femoral ;  it  is  often  given  off  from  the  profunda  by  a  common  trunk  with 
the  great  muscular  artery  of  the  triceps,  and  it  may  then  be  regarded  as  fonned  by  the 
bifurcation  of  the  profunda  :  it  passes  horizontally  behind  the  rectus  femoris,  crossing 
in  front  of  the  psoas  and  iliacus,  to  which  it  gives  a  rather  large  vessel,  and  then  divides 
into  two  branches  :  an  ascending  muscular,  Avliich  is  distributed  to  the  glutaeus  minimus 
and  to  the  tensor  vaginse  femoris  ;  and  a  circumflex  branch,  properly  so  called,  which 
turns  round  the  base  of  the  great  trochanter  {f,flg.  215),  dips  into  the  substance  of  the 
triceps,  and  expands  into  a  great  number  of  ascending  branches,  which  anastomose  w  ith 
the  internal  circumflex  upon  the  outer  surface  of  the  great  trochanter.  Not  unfrequent- 
ly,  an  anastomosis  is  formed  in  front  by  a  transverse  branch  between  the  internal  and  ex- 
ternal circumflex  arteries,  by  which  the  arterial  circle  of  the  hip-joint  is  completed. 

The  perforating  arteries  (r  r,fig.  214)  are  both  muscular  and  cutaneous,  and  are  intend- 
ed for  the  posterior  region  of  the  thigh  :  they  vary  in  number  from  one  to  four,  and  are 
all  distributed  in  a  similar  manner.  They  perforate  the  tendinous  attachments  of  the 
adductor  muscles  to  the  femur,  and,  having  reached  the  back  of  the  thigh,  they  turn 
horizontally  round  the  bone,  and  divide  into  ascending  and  descending  branches,  which 
form  a  series  of  loops  or  anastomotic  arches  in  the  substance  of  the  muscles ;  these 
loops  acquire  a  great  size  in  cases  where  the  femoral  has  been  tied  after  Hunter's  meth- 
od, i.  e.,  in  the  middle  third  of  the  thigh. 

The  first  perforating  artery  {r,fig.  215),  which  is  the  largest,  and  sometimes  repre- 
sents two,  or  even  the  whole  of  the  perforating  arteries,  passes  through  the  great  ad- 
ductor about  one  inch  below  the  lesser  trochanter,  between  the  horizontal  and  oblique 
fibres  of  the  muscle  ;  its  ascending  branch  («)  turns  round  the  great  trochanter,  and  anas- 
tomoses with  the  internal  circumflex  and  sciatic  in  the  substance  of  the  glutaeus  maxi- 
mus ;  its  descending  branch  (Z)  is  distributed  to  the  vastus  externus,  the  semi-tendinosus, 
semi-membranosus,  biceps,  and  adductor  magnus  muscles.  Some  branches  ramify  upon 
the  great  sciatic  nerve.* 

I  have  seen  an  inferior  perforating  artery  arise  from  the  femoral,  just  where  it  passed 
through  the  tendon  of  the  adductor  magnus. 

The  terminal  branch  (d',flg.  214)  of  the  deep  femoral  constitutes  the  last  perforating 
artery,  which  is  distributed  in  the  same  manner  as  the  other  arteries  of  that  name. 

The  Popliteal  Arteky. 
When  the  femoral  artery  has  perforated  the  tendinous  portion  of  the  adductor  magnus, 
it  takes  the  name  of  the  popliteal  artery,  which  extends  down  to  its  division  into  the  an- 
terior tibial  and  tibio-peroneal  arteries. 

*  The  principal  nutritious  artery  of  the  femur  arises  from  the  first  or  second  perforating  artery. 


THE    POPLITEAL   ARTERY. 


ffe 


The  popliteal  artery  {o,figs.  215,  217)  is  the  artery  of  the  ham  or  popliteal  space  ;  it 


Fig.  215. 


is  bounded  above  (p,fig-  215)  by  the  tendinous  ring  formed 
in  the  adductor  niagnus,  and  below  (p,  fig.  217)  by  the  low- 
er border  of  the  popliteus  muscle,  at  which  place  it  is  sit- 
uated opposite  the  lower  end  of  the  upper  fourth  of  the 
leg.*    Its  length  in  an  adult  subject  is  about  seven  inches. 

It  passes  vertically,  or  somewhat  obliquely  outward  and 
downward,  the  direction  of  the  artery  being  represented 
by  a  line  extending  from  the  inner  surface  of  the  femur  to 
the  space  between  its  two  condyles.  It  is  tortuous  when 
the  leg  is  flexed  upon  the  thigh,  but  it  becomes  straight 
when  the  leg  is  extended,  and  may  be  ruptured  by  very 
forcible  extension.  It  has  been  proved  by  experiment, 
that  extension  may  be  carried  as  far  as  to  cause  lacera- 
tion of  the  ligaments  of  the  joint,  without  rupturing  the  ar- 
tery, t 

Relations. — It  is  situated  deeply  in  the  whole  of  its 
course,  and  it  is  in  relation,  behind,  with  the  semi-mem- 
branosus  above ;  lower  down,  with  the  popliteal  fascia, 
from  which  it  is  separated  by  a  layer  of  fat  of  greater  or 
less  thickness,  according  to  the  prominence  of  the  ham- 
string muscles  ;  below  this,  with  the  gastrocnemius  and 
plantaris  muscles  ;  and  still  lower,  with  the  soleus.  The 
popliteal  vein  lies  behind  and  slightly  to  the  outer  side  of 
the  artery,  and  then  behind  it,  adhering  rather  firmly  to 
it.  The  internal  popliteal  nerve  also  lies  upon  it  behind, 
but  is  separated  from  it  by  a  very  thick  layer  of  fat.  The 
veins  and  nerves  both  cross  the  artery  beneath  the  gas- 
trocnemius, so  as  to  get  to  the  inner  side  of  the  lower 
portion  of  the  vessel. 

From  these  relations,  it  follows  that  the  popliteal  artery 
may  be  exposed  from  behind  in  the  whole  of  its  extent, 
but  that  it  is  deeper  seated  below  than  above. 

hi  front,  it  is  in  relation,  from  above  downward,  with 
the  adductor  magnus  ;  with  the  internal  surface  of  the  fe- 
mur, which  appears  to  be  expanded  and  become  posterior, 
so  as  to  support  the  vessel ;  with  the  knee-joint,  with 
which  it  is  in  direct  contact ;  and,  lastly,  with  the  popli- 
teus muscle.  The  direct  relation  of  the  popliteal  artery  with  the  joint  explains  the  fa- 
cihty  with  which  it  may  be  lacerated  when  its  tissue  has  been  rendered  fragile  from  or- 
ganic change,  and  accounts  for  the  frequency  of  aneurism  in  this  region. 

On  the  inner  side,  this  artery  is  in  relation  with  the  semi-membranosus,  the  inner  con- 
dyle of  the  femur,  and  the  inner  head  of  the  gastrocnemius. 

On  its  outer  side,  it  has  the  biceps,  the  outer  condyle,  the  outer  head  of  the  gastroc- 
nemius, and  also  the  plantaris  and  soleus  muscles. 

Collateral  Branches. — The  popliteal  artery  gives  off- from  its  posterior  aspect  several 
small  branches,  which  pass  into  the  muscles  of  the  ham ;  most  of  them  are  not  named ; 
but  there  are  some  which  are  distinguished  as  the  sural  arteries :  in  front  it  gives  sev- 
eral arteries,  named  articular,  because  they  surround  the  knee,  like  the  collateral  arter- 
ies of  the  elbow-joint.  The  articular  arteries  are  divided  into  superior,  middle,  and  in- 
ferior ;  the  superior  and  inferior  would  have  been  better  named  the  collateral  arteries  of 
the  knee. 

The  sural  arteries  {g g,fig*-  215,  217)  are  two  in  number:  one  internal,  for  the  innei 
head  of  the  gastrocnemius,  and  the  other  external,  for  the  outer  head  of  the  same  muscle. 
Arising  from  the  back  of  the  popliteal  artery,  they  pass  downward  and  backward,  are 
separated  from  each  other  by  the  internal  popliteal  nerve,  enter  the  anterior  and  inter- 
nal surface  of  each  head  of  the  gastrocnemius  a  little  before  the  two  heads  meet,  and 
may  be  traced  down  to  the  lower  part  of  the  fleshy  belly  of  that  muscle.  Generally  one 
of  their  branches  accompanies  the  external  saphenous  nerve  from  the  popliteal  space  to 
the  upper  part  of  the  tendo  Achillis. 

The  superior  articular  or  collateral  arteries  of  the  knee  are  divided  into  internal  and 
external. 

The  internal  superior  articular  arteries  are  sometimes  three,  but  most  commonly  two 
in  number,  one  of  which  arises  higher  than  the  other  ;  their  origin  is  subject  to  variety, 

*  The  divisioa  of  the  popliteal  artery  takes  place  sowetiraes  higher,  sometimes  lower  than  usual.  In  a  case 
■where  its  bifurcation  was  premature,  the  anterior  tibial  has  been  seen  passing  between  the  popliteus  muscle 
and  the  posterior  face  of  the  til)ia. 

t  I  have  had  an  opportunity  of  observing  a  case  of  luxation  of  the  knee,  with  complete  laceration  of  the 
crucial  ligaments,  where  the  popliteal  artery  was  left  entire. 


566  ANGEIOLOGY. 

but  they  are  constant  in  their  distribution.  We  sheill  distinguish  them  as  the  first  and 
second. 

The  first  internal  superior  articular  artery,  usually  called  the  great  anastomotic  artery 
of  the  knee,  is  the  largest  of  the  whole  :  it  arises  opposite  the  point  where  the  femoral 
becomes  the  popliteal  artery,  and  sometimes  even  from  the  lower  part  of  the  femoral  it- 
self; it  perforates  the  adductor  magnus  from  behind  forward,  and  immediately  divides 
into  four  descending  branches:  the  first  is  a  muscular  branch  {i,fig.  214),  which  enters 
the  substance  of  the  vastus  internus,  passes  inward  and  downward  to  reach  the  inner 
border  of  the  tendon  of  the  triceps,  and,  opposite  the  base  or  upper  border  of  the  patella, 
perforates  the  fibres  of  the  muscle,  becomes  superficial,  and  runs  transversely  outward 
along  the  base  of  the  patella,  and  forms  an  anastomotic  arch  with  the  external  superior 
articular  artery.  The  second  and  third  branches  are  periosteal ;  one  of  them  passes  be- 
tween the  triceps  and  the  femur,  with  which  it  is  in  contact,  and  terminates  above  the 
trochlea  of  that  bone  by  anastomosing  (at  s)  with  the  external  superior  and  the  second 
internal  superior  articular  arteries  ;  while  the  other  runs  along  the  adductor  magnus, 
being  held  down  against  it  by  a  layer  of  fibrous  tissue,  and  anastomoses  with  tlie  second 
internal  superior  articular  artery,  supplying  its  place  when  that  vessel  is  only  in  a  rudi- 
mentary state.  The  fourth  branch  (A)  accompanies  and  supplies  branches  to  the  inter- 
nal saphenous  nerve  :  it  appears  to  be  constant ;  it  is  placed  under  the  sartorius,  along 
which  it  runs,  together  with  the  internal  saphenous  nerve,  continuing  with  it  below  that 
muscle. 

The  second  internal  superior  articular  artery  {h,figs.  215,  217)  arises  immediately  above 
the  inner  condyle  of  the  femur,  turns  round  it  horizontally,  and  divides  into  condyloid 
branches,  which  cover  the  condyles  with  their  ramifications,  and  communicate  partly 
with  the  first  internal  superior  articular  artery,  and  partly  with  the  external  superior  ar- 
ticular artery  coming  from  the  opposite  side.  It  also  gives  off  a  patellar  branch,  which 
runs  upon  the  borders  of  that  bone,  supplies  the  skin  and  the  synovial  membrane  of  the 
knee-joint,  and  anastomoses  with  the  internal  inferior  articular  artery. 

The  external  superior  articular  artery  {i,figs.  215,  217)  arises  opposite  the  second  in- 
ternal superior,  turns  horizontally  round  the  outer  condyle  of  the  femur,  gives  off  some 
ascending  muscular  branches,  which  ramify  in  the  vastus  externus,  and  then  terminates 
in  three  periosteal  branches.  One,  which  is  superior  and  transverse,  turns  round  the 
lower  end  of  the  femur,  and  anastomoses  with  the  corresponding  branch  of  the  second 
internal  superior  articular ;  another  and  inferior  branch  ramifies  upon  the  inner  condyle, 
and  anastomoses  freely  by  a  great  number  of  branches  with  the  external  inferior  articu- 
lar ;  the  third  is  a  more  superficial  branch  for  the  patella,  on  the  side  of  which  bone  it 
runs,  and  near  its  upper  border  gives  off  a  transverse  twig,  which  anastomoses  on  the 
upper  border  of  the  patella  with  a  similar  one  from  the  internal  superior  articular  arter- 
ies, and  a  descending  twig,  which  runs  along  the  outer  border  of  the  bone,  and  anasto- 
moses with  the  external  inferior  articular  artery. 

The  inferior  articular  or  collateral  arteries  of  the  knee  are  also  divided  into  the  internal 
and  the  external.  They  both  arise  from  the  front  of  the  popliteal  artery,  opposite  the 
middle  of  the  knee-joint. 

The  internal  inferior  articular  artery  {c,fig.  217)  runs  downward  and  inward,  and,  hav- 
ing reached  the  internal  tuberosity  of  the  tibia,  turns  horizontally  forward,  passes  be- 
neath the  tendons  of  the  semi-teHdinosus,  semi-membranosus,  and  gracilis  muscles,  and 
also  beneath  the  internal  lateral  ligament  of  the  knee,  turns  upward  upon  the  inner  side 
of  the  anterior  tuberosity  of  the  tibia  and  ligamentum  patellaj,  describing  a  curve  with 
its  concavity  directed  upward,  and  anastomoses  either  with  the  superior  articular  arter- 
ies or  with  the  anterior  tibial  recurrent.  During  its  course  it  gives  off  ascending  and 
descending  periosteal  and  osseous  branches.* 

The  external  inferior  articular  artery  {b,fig.  217)  arises  opposite  the  internal  vessel, 
turns  horizontally  forward,  not  upon  the  external  tuberosity  of  the  tibia  (for  this  is  pre- 
vented by  the  tibio-fibular  articulation),  but  upon  the  convex  borders  of  the  external 
semilunar  cartilage,  passes  beneath  the  tendon  of  the  biceps  and  the  external  lateral 
ligament  of  the  knee-joint,  and  terminates  by  dividing  into  an  ascending  branch,  which 
runs  upward  along  the  outer  border  of  the  patella,  a  descending  branch,  which  anasto- 
moses with  the  anterior  tibial  recurrent,  and  a  transverse  branch,  which  passes  behind 
the  ligamentum  patellae  below  the  patella,  and  anastomoses  with  a  similar  branch  from 
the  internal  inferior  articular.  The  inferior  articular  arteries  complete  the  arterial  circle 
which  surrounds  the  patella,  and  from  which  numerous  branches  are  given  off,  some 
covering  the  patella  by  their  anastomoses,  and  others  entering  the  bone  directly  through 
the  numerous  foramina  which  exist  upon  its  surface. 

The  middle  articular  arteries  (*,  fig.  215)  consist  of  several  small  branches,  which  arise 
directly  from  the  front  of  the  popliteal  artery,  or  from  the  external  inferior  articular,  run 
from  behind  forward  into  the  interior  of  the  knee-joint,  and  are  distributed  in  the  inter- 
condyloid  notch  to  the  crucial  ligaments,  the  adipose  tissue,  the  synovial  membrane,  and 

*  By  osseous  branches  I  mean  those  which  enter  the  bone  directly  through  the  foramina,  on  the  internal 
and  external  tuberosities  of  the  tibia. 


THE    ANTERIOR    TIBIAL   ARTERY. 


567 


especiaDy  to  the  lower  extremity  of  the  femur,  which  they  penetrate  through  the  large 
foramina  on  the  adjacent  surface  of  each  condyle.  The  middle  articular  artery  or  arter- 
ies belong,  therefore,  to  the  knee-joint  exclusively,  and  do  not  assist  in  the  restoration 
of  an  impeded  circulation :  in  this  respect  they  differ  entirely  from  the  other  articular 
arteries,  which  acquire  a  very  considerable  size  when  the  principal  trunk  has  been  tied. 

The  Anterior  Tibial  Artery. 

Opposite  the  lower  border  of  the  popliteus  muscle,  the  pophteal  artery  divides  into 
two  branches  :  an  anterior,  named  the  anterior  tibial  {a,  Jig.  217) ;  and  a  posterior,  which 
forms  the  continuation  of  the  popliteal,  and  may  be  denominated  the  tibio-peraneal  trunk 
(/).     This  trunk  soon  subdivides  into  the  posterior  tibial  (t)  and  the  peroneal  {k)  arteries. 

The  anterior  tibial  artery  {a,  Jigs.  216,  217),  the  anterior  branch  of  the  bifurcation  of 
the  popliteal,  terminates  opposite  the  dorsal  annular  ligament  of  the  Fig.  216. 

tarsus  (J),  Jig.  216),  below  which  the  vessel  is  named  the  dorsal  artery 
oj  the  foot  (/).  Immedidtely  after  its  origin,  it  passes  horizontally 
forward,  perforates  the  upper  part  of  the  interosseous  ligament,  is  re- 
flected over  it,  and  descends  vertically  in  front  of  it ;  having  reached 
the  lower  fourth  of  the  leg,  it  is  directed  somewhat  obliquely  inward, 
following  the  direction  of  the  external  surface  of  the  tibia,  and  then 
passes  under  the  annular  ligament,  at  the  lower  border  of  which,  as 
stated,  it  terminates. 

A  line  stretched  from  that  process  of  the  tibia,  which  has  been  de- 
scribed as  the  tubercle  of  the  tibialis  anticus  (Osteology,  p.  278),  to 
the  middle  of  the  tibio-tarsal  articulation,  will  indicate  its  direction 
and  course. 

Relations. — The  anterior  tibial  artery  is  situated  very  deeply,  and 
yet  it  can  be  exposed  at  any  point ;  it  is  in  relation,  behind,  with  the  |  f 
interosseous  ligament  in  its  three  upper  fourths,  and  with  the  tibia  in 
its  lower  fourth ;  it  lies  in  contact  with  the  interosseous  ligament, 
and  is  retained  in  its  place  by  a  layer  of  fibrous  tissue,  so  that,  after 
amputation  of  the  leg,  it  retracts  between  these  two  fibrous  layers, 
and  is  sometimes  seized  and  tied  with  difficulty. 

In  front,  it  is  covered  successively  by  the  tibialis  anticus,  the  ex- 
tensor longus  digitorum,  and  the  extensor  proprius  poUicis,  the  ten- 
don of  which  crosses  over  it ;  it  is  placed  exactly  along  the  cellular 
interval  between  the  tibijdis  anticus  and  the  extensor  muscles ;  and 
the  incision  should,  therefore,  be  made  along  the  line  corresponding 
to  that  interval,  in  order  to  expose  the  artery  when  it  is  to  be  tied ; 
lower  down  it  is  only  separated  from  the  skin  by  the  fascia  of  the  leg 
and  the  projecting  tendon  of  the  extensor  proprius  pollicis,  and  hence 
it  may  be  compressed  in  this  situation.  UiPS?iiif  <i 

On  the  inner  side,  it  is  in  relation  with  the  tibialis  anticus,  then  with 
the  tibia,  and,  lastly,  with  the  tendon  of  the  extensor  pollicis,  being 
lodged  in  the  same  sheath- 

On  its  outer  side,  it  has  the  extensor  longus  digitorum,  then  the  ex- 
tensor pollicis,  both  of  which  afterward  cross  over  it ;  and,  lastly,  it 
has  only  the  fascia  of  the  leg :  the  anterior  tibial  nerve  runs  along  the 
outer  side  of  the  artery  in  its  whole  extent. 

Its  collateral  branches  are  very  small  and  numerous,  and  are  distrib- 
uted to  the  muscles  and  the  skin.  Among  them,  the  anterior  tibial 
recurrent,  and  the  external  and  internal  malleolar,  require  special  notice. 

The  anterior  tibial  recurrent  artery  (c,Jig.  216)  is  sometimes  of  considerable  size  ;  it 
arises  from  the  tibial,  after  that  vessel  is  disengaged  from  the  interosseous  ligament, 
passes  obhquely  upward  and  inward  between  the  tibialis  anticus  and  the  external  tuber- 
osity of  the  tibia,  with  which  it  is  in  contact,  and  expands  into  diverging,  periosteal,  and 
articular  branches,  some  of  which  ascend  and  anastomose  with  the  external  inferior  ar- 
ticular of  the  knee,  while  others  pass  transversely,  and  anastomose  with  the  internal  in- 
ferior articular.  I  have  seen  the  anterior  tibial  recurrent,  of  large  size,  run  transversely 
below  the  patella,  and  terminate  upon  the  internal  tuberosity  of  the  tibia. 

The  malleolar,  which  would  be  more  correctly  named  articular  arteries,  are  divided 
into  the  internal  and  external. 

The  internal  malleolar  or  articular  artery  (d)  arises  opposite  the  dorsal  annular  ligament 
of  the  tarsus,  passes  transversely  inward  under  the  tendon  of  the  tibialis  anticus,  and  di- 
vides into  two  branches  :  a  deep,  or  articular,  which  dips  perpendicularly  into  the  ankle- 
joint,  and  is  distributed  to  that  articulation;  and  a  superjicial,  or  malleolar,  properly  so 
called,  which  passes  above  the  malleolus,  and  is  distributed  upon  it,  on  the  inner  side 
of  the  tarsus,  as  far  as  the  internal  plantar  region,  where  it  anastomoses  with  the  branch- 
es of  the  internal  plantar  artery. 

The  external  malleolar  or  articular  artery  (I),  larger  than  the  preceding,  vart-s  much  in 


568  ANGEIOLOGY. 

its  origin.  Thus,  it  sometimes  arises  under  the  dorsal  ligament  of  the  tarsus,  opposite 
the  internal  malleolar ;  it  often  arises  from  the  tibial,  about  two  or  three  inches  above 
the  annular  ligament.  Sometimes  it  is  derived  from  the  posterior  peroneal  artery,  and 
perforates  the  lower  part  of  the  interosseous  ligament.  Lastly,  and  most  commonly, 
it  arises  by  two  roots ;  one  of  which  is  small,  but  variable  in  size,  and  is  derived  from  the 
peroneal,  while  the  other  is  larger,  and  is  given  off  from  the  anterior  tibial. 

These  differences  of  origin  affect  the  course  of  the  artery.  When  it  arises  under  the 
Ugament  of  the  tarsus,  it  passes  transversely  outward,  and  then  turns  in  front  of  the  ex- 
ternal malleolus  to  run  forward,  resting  upon  the  tarsus.  It  receives  the  branch  from 
the  posterior  peroneal  at  the  point  where  it  changes  its  direction.  In  those  cases  where 
it  arises  higher,  it  passes  obliquely  downward,  in  front  of  the  external  malleolus,  and 
then  upon  the  outer  side  of  the  astragalus.  In  all  cases,  the  external  malleolar  artery 
runs  forward  on  the  outer  side  of  the  cuboid  bone,  and  forms  an  anastomotic  arch  with 
the  dorsjd  artery  of  the  tarsus.  It  is  in  contact  with  the  booes  througliout  its  course, 
and  is  crossed  by  the  tendon  of  the  extensor  longus  digitonim  :  it  gives  off  malleolar 
branches,  which  ramify  upon  the  outer  surface  of  the  external  malleolus  ;  very  large  ar- 
ticular branches,  which  dip  into  the  tibio-tarsal  articulation  ;  and  one,  which  I  would  es- 
pecially notice,  that  enters  the  deep  fossa  between  the  astragalus  and  os  calcis ;  and, 
lastly,  external  calcaneal  branches,  which  pass  under  the  tendons  of  the  peroneus  longus 
and  peroneus  brevis,  and  ramify  upon  the  outer  side  of  the  os  calcis,  where  they  termi- 
nate by  anastomosing  with  the  peroneal  artery,  and  with  some  branches  of  the  external 
plantar.  Several  of  these  branches  are  reflected  upon  the  upper  surface  of  the  os  calcis  in 
front  of  the  tendo  Achillis,  and  anastomose  with  branches  from  the  posterior  tibial  artery. 

The  Dorsal  Artery  of  the  Foot. 

The  dorsal  artery  of  the  foot  {dorsalis  pedis,  f,Jig.  216)  is  the  continuation  of  the  an- 
terior tibial,  which  takes  this  name  after  emerging  from  below  the  dorsal  annular  liga- 
ment of  the  tarsus  ;  it  terminates  in  the  sole  of  the  foot,  by  becoming  continuous  with 
the  plantar  arch.  Not  unfrequently  this  artery  arises  by  two  roots,  one  of  them  being 
formed  by  the  anterior  tibial,  which  is  much  smaller  than  usual,  and  is,  as  it  were,  ex- 
hausted near  the  ankle,  and  the  other  by  the  peroneal,  which  is  then  very  large,  and  per- 
forates the  lower  part  of  the  interosseous  ligament.  In  a  few  rare  cases,  the  anterior 
tibial  is  entirely  wanting,  and  is  represented  by  some  small  perforating  branches  from 
the  posterior  tibial  or  the  peroneal ;  the  dorsal  artery  of  the  foot  is  then  wholly  derived 
from  the  peroneal. 

The  size  of  the  dorsal  artery  of  the  foot  is  also  subject  to  variety;  it  generally  bears 
a  direct  proportion  to  that  of  the  anterior  tibial,  which  I  have  seen  as  large  as  the  poste- 
rior tibial  and  peroneal  arteries  together,  while  it  has  an  inverse  ratio  to  that  of  the  two 
last-mentioned  vessels  combined. 

The  dorsal  artery  runs  horizontally  and  directly  forward  upon  the  dorsum  of  the  foot, 
as  far  as  the  posterior  extremity  of  the  first  interosseous  space,  at  which  point  it  bends 
downward  at  a  right  angle,  perforates  that  space  like  a  perforating  artery,  and  termi- 
nates by  becoming  continuous  with  the  plantar  arch. 

The  direction  of  the  dorsal  portion  of  this  artery  is  marked  by  a  line  extending  from 
the  middle  of  the  tibio-tarsal  articulation  to  the  posterior  extremity  of  the  first  interos- 
seous space. 

Relations. — It  lies  in  contact  with  the  bones  of  the  tarsus,  in  which  position  it  is  re- 
tained by  a  layer  of  fibrous  tissue.  It  is  separated  from  the  skin  by  the  fascia  of  the 
foot,  and  also  anteriorly  by  the  inner  portion  of  the  extensor  brevis  digitorum.  It  runs 
along  the  outer  side  of  the  tendon  of  the  extensor  proprius  pollicis,  which  projects  so  as 
to  raise  the  integuments  from  the  vessel ;  it  may  be  exposed  in  its  entire  length  by  cut- 
ting along  the  outer  border  of  that  tendon.  It  is  not  uninteresting  to  remark  that,  un- 
der the  dorsal  ligament  of  the  tarsus,  this  artery  is  situated  in  the  same  sheath  as  the 
tendon  of  the  extensor  proprius  pollicis. 

Its  collateral  branches  are  internal  and  external. 

The  internal  branches  are  numerous,  but  are  not  named  ;  they  ramify  upon  the  inner 
side  of  the  tarsus,  and  anastomose  upon  the  inner  border  of  the  foot,  either  with  each 
other,  with  the  internal  malleolar  arteries,  or  with  the  internal  plantar  artery.  One  of 
them  may  be  described  under  the  name  of  the  internal  tarsal  artery,  a  branch  which 
has  a  remarkable  course  :  it  passes  obliquely  forward  and  inward  as  far  as  the  posterior 
extremity  of  the  first  metatarsal  bone,  and  is  sometimes  continued  along  the  inner  side 
of  that  bone  to  form  the  internal  collateral  artery  of  the  great  toe  ;  at  other  times  it  is 
reflected  under  the  first  metatarsal  bone,  and  anostomoses  directly  with  the  internal 
plantar  artery,  after  having  given  off  a  great  number  of  branches  to  the  inner  side  of  the 
metatarso-phalangal  articulation  of  the  great  toe. 

Among  the  external  branches  there  are  two  which  require  particular  description,  viz., 
the  dorsal  artery  of  the  tarsus,  or  the  external  tarsal,  and  the  dorsal  artery  of  the  metatarsus 
or  the  metatarsal  artery. 

The  external  tarsal  artery  {g)  varies  in  its  size,  which  almost  always  bears  an  inverse 


THE    TIBIO-PERONEAL    ARTERY. 


569 


proportion  to  that  of  the  external  malleolar  and  metatarsal  arteries.  I  have  seen  it  as 
large  as  the  dorsal  artery  of  the  foot,  by  the  bifurcation  of  which  vessel  it  appeared  to  be 
formed. 

It  passes  transversely  outward  under  the  extensor  brevis  digitorum,  anastomoses 
freely  with  the  external  malleolar  artery,  and  gives  off  the  following  branches  :  some 
which  ramify  upon  the  outer  side  of  the  os  calcis,  and  anastomose  with  the  peroneal ;  a 
branch  which  runs  upon  the  cuboid  bone,  sometimes  being  so  large  as  to  be  regarded 
the  continuation  of  the  artery,  and  then  passes  under  the  sole  of  the  foot  to  anastomose 
with  the  external  plantar  ;  and,  lastly,  some  branches  in  front,  which  anastomose  with 
the  metatarsal  artery,  the  place  of  which  vessel  it  sometimes  partially  supplies,  by  giv- 
ing off  the  dorsal  interosseous  arteries.  In  one  case,  where  the  external  tarsus  artery 
was  very  large,  it  passed  transversely  outward  as  far  as  the  outer  surface  of  the  cuboid 
bone,  was  reflected  backward  on  the  outer  surface  of  the  calcaneum,  and  there  anasto- 
mosed very  freely  with  the  external  malleolar  and  the  peroneal  arteries.  In  another 
case,  the  external  tarsal  artery  divided  into  two  branches,  one  of  which  ran  transversely 
outward  and  reached  below  the  sole  of  the  foot,  while  the  other  formed  the  dorsal  inter- 
osseous artery  of  the  fourth  interosseous  space. 

The  metatarsal  artery  (h)  generally  arises  from  the  front  of  the  dorsal  artery  of  the 
foot,  opposite  the  posterior  extremity  of  the  first  interosseous  space,  sometimes  by  a 
common  trunk  with  the  external  tarsal  just  described.  According  to  the  most  regular 
distribution,  it  passes  transversely  outward,  opposite  the  posterior  extremities  of  the 
several  metatarsal  bones,  and  constitutes  the  dorsal  arch  of  the  metatarsus  (?). 

Three  branches  given  off  from  the  convexity  of  this  arch,  which  is  directed  forward, 
are  named  the  dorsal  interosseoas  arteries  {I  I).  They  run  along  the  dorsal  surface  of  the 
second,  third,  and  fourth  interosseous  spaces,  and  having  arrived  opposite  the  metatarso- 
phalangal  articulations,  divide  into  two  collateral  branches  for  the  corresponding  toes. 
During  its  course  along  its  own  interosseous  space,  each  dorsal  interosseous  artery  re- 
ceives two  perforating  branches,  viz.,  a  posterior  perforating  artery,  opposite  the  posterior 
extremity  of  the  interosseous  space,  and  an  anterior  perforating,  opposite  the  anterior  ex- 
tremity of  the  same  space.  This  explains  the  otherwise  sin- 
gular fact,  that  the  dorsal  interosseous  arteries  are  increased 
in  size  opposite  the  posterior  and  anterior  extremities  of  their 
respective  spaces.  In  some  subjects,  the  dorsal  interosseous 
arteries  are  derived  exclusively  from  the  perforating  arteries. 

It  is  not  very  rare  to  find  the  metatarsal  and  the  dorsal  inter- 
osseous arteries  wanting ;  their  places  are  then  supphed  by  the 
plantar  interosseous  arteries. 

The  dorsal  interosseous  artery  of  the  first  interosseous  space  (n) 
is  given  off  directly  from  the  dorsal  artery  of  the  foot,  at  the 
point  where  that  artery  dips  into  the  first  interosseous  space  ; 
it  is  larger  than  the  other  dorsal  interosseous  arteries,  but  is 
distributed  in  a  similar  manner. 

The  dorsal  interosseous  artery  of  the  second  space  is  also 
rather  frequently  derived  directly  from  the  dorsalis  pedis. 

The  Tibio-peroneal  Artery. 

'*  The  tihio-peroneal  artery  or  trunk  (^f,fig-  217),  the  posterior 
branch  of  the  bifurcation  of  the  popliteal  artery,  is  bounded 
above  by  the  origin  of  the  anterior  tibial,  and  below  by  its  sub- 
division into  two  branches,  viz.,  the  posterior  tibial  (Z)  and  the 
peroneal  (^■).  It  is  from  one  inch  to  eighteen  lines  in  length, 
sometimes  it  is  not  more  than  six  lines,  and  it  may  be  two  or 
even  three  inches  ;  I  have  seen  it  extend  as  low  as  the  inner 
part  of  the  os  calcis,  where  it  divided  into  the  internal  and  ex- 
ternal plantar  arteries.*  ' 

It  forms  the  continuation  of  the  popliteal  in  regard  to  direc- 
tion, and  is  in  relation  with  the  soleus  behind  and  the  muscles 
of  the  deep  layer  in  front ;  the  posterior  tibial  nerve  crosses 
behind  to  get  to  its  outer  side  below. 

The  collateral  branches  of  the  tibio-peroneal  artery  are,  first, 
an  internal  recurrent  branch,  which  perforates  the  soleus  from 
behind  forward,  turns  round  upon  the  inner  border  of  the  tibia, 
is  reflected  upward,  and  anastomoses  with  the  internal  inferior 
articular  artery  upon  the  internal  tuberosity  of  that  bone  ;  sec- 
ondly, the  nutritious  artery  of  the  tibia  (s) ;  and,  lastly,  a  single 
large  branch,  or  several  branches,  to  the  soleus  muscle,  which 

*  M.  Dubreuil  has  communicated  to  me  n  case  in  which  the  tibio-peroneal  trunk  continued  undivided  al' 
along  the  posterior  face  of  the  peroneus,  and  gave  off  the  posterior  tibial  artery  only  at  the  lower  part  of  the  leg 

4  0 


';:StO  .'/J?.-.'  ANGEIOLOGY. 

they  enter  near  its  peroneal  attachments,  and  then  anastomose  with  the  anterior  tibial 
and  the  external  inferior  articular.  When  the  tibio-peroneal  artery  is  short,  the  branch 
to  the  soleus  is  derived  from  the  peroneal  artery. 

The  Peroneal  Artery. 

The  peroneal  artery  (i)  extends  from  the  bifurcation  of  the  tibio-peroneal  trunk  to  the 
OS  calcis.  It  is  generally  smaller  than  the  posterior  tibial,  and  even  than  the  anterior 
tibial,  and  bears  an  inverse  proportion  to  the  size  of  the  two,  more  particularly  to  that 
of  the  anterior  tibial,  the  place  of  which  it  often  partially  supplies.  In  some  cases  it  is 
itself  replaced  by  some  small  branches  derived  from  the  posterior  tibial.* 

It  descends  vertically  along  the  posterior  surface  of  the  fibula,  from  which  it  is  separ- 
ated by  the  flexor  longus  pollicis  ;  it  is  covered  by  the  soleus,  and  dips  below  between 
the  flexor  longus  pollicis  and  the  tibialis  posticus,  to  reach  the  interosseous  ligament,  at 
the  lower  part  of  which  it  divides  into  a  posterior  and  an  anterior  branch. 

Its  collateral  branches  are,  first,  posterior  ones,  which  are  very  numerous,  and  supply 
the  soleus  ;  the  highest  of  these  are  of  considerable  size,  and  often  arise  from  the  tibio- 
peroneal  artery.  Secondly,  there  are  internal  and  external  branches,  which  pass  to  the 
deep-seated  muscles  of  the  leg  :  among  the  external  branches  is  the  nutritious  artery  of 
the  fibula ;  and  among  the  internal  branches  a  transverse  or  oblique  anastomotic  twig 
may  be  specially  noted,  which  extends  from  the  peroneal  to  the  posterior  tibial.  Some- 
times this  anastomotic  branch  is  very  large,  and,  in  that  case,  the  posterior  tibial  is  more 
slender  than  usual  up  to  that  point,  but  increases  in  size  after  receiving  this  addition, 
and  afterward  gives  off  the  plantar  arteries. 

Terminal  Branches. — The  anterior  terminal  branch,  named  the  peroneal  perforating,  oi 
the  anterior  peroneal  artery  {g,fig.  216),  perforates  the  lower  part  of  the  interosseous  lig- 
ament, descends  upon  the  lower  end  of  the  tibia,  and  anastomoses  with  the  external 
malleolar  artery,  which  is  sometimes  formed  by  it.  This  peroneal  perforating  branch, 
which  is  generally  very  small,  is  sometimes  as  large,  or  even  larger,  than  the  posterior 
branch,  and  then  supplies  the  place  of  the  lower  part  of  the  anterior  tibial,  and  forms  the 
dorsal  artery  of  the  foot ;  the  anterior  tibial  is  then  very  small.  There  almost  always 
exists  a  trace  of  this  distribution  in  the  presence  of  a  small  branch,  which  anastomoses 
with  the  anterior  tibial. 

The  posterior  terminal  branch  (I,  Jig.  217)  of  the  peroneal  artery,  which  might  be  called 
the  external  calcaneal,  forms  the  continuation  of  that  vessel,  and  gains  the  posterior  as- 
pect of  the  external  malleolus,  to  which  it  is  applied,  after  running  along  the  outer  bor- 
der of  the  tendo  Achillis,  being  separated  from  the  skin  by  the  fascia  of  the  leg  and  an- 
other layer  of  fibrous  tissue.  It  gives  off  to  its  inner  side,  opposite  the  posterior  border 
of  the  lower  end  of  the  tibia,  a  transverse  branch,  which  anastomoses  with  the  posterior 
tibial  artery.  It  then  ramifies  upon  the  outer  surface  of  the  os  calcis,  supplies  the  cal- 
caneal attachments  of  the  muscles  of  the  sole  of  the  foot,  and  also  the  skin  of  the  heel, 
and  anastomoses  with  the  external  malleolar,  and  also  with  the  external  plantar  artery. 
Some  small  ascending  branches  pass  above  the  os  calcis,  and  anastomose  in  front  of  the 
tendo  Achillis  with  corresponding  branches  of  the  posterior  tibial.  I  have  seen  the  ev 
ternal  calcaneal  artery  derived  from  the  posterior  tibial. 

The  Pbsterior  Tibial  Jlrtery. 

The  posterior  tibial  artery  (t,  Jig.  217)  is  the  internal  branch  of  the  bifurcation  of  the 
tibio-peroneal  artery  or  trunk,  and  having  entered  a  groove  on  the  os  calcis,  beneath  the 
internal  annular  ligament  of  the  tarsus  {t,Jig.  218),  terminates  by  dividing  into  the  inter- 
nal (a)  and  the  external  {b)  plantar  arteries.  It  is  larger  than  the  other  arteries  of  the  leg, 
and  is  generally  inversely  proportioned  to  the  anterior  tibial  and  the  peroneal.  Thus,  in 
a  subject  in  which  the  anterior  tibial  and  the  dorsal  artery  of  the  foot  were  very  large, 
the  posterior  tibial  and  the  internal  plantar  were  scarcely  one  third  of  their  ordinary  size. 

The  posterior  tibial  artery  is  at  first  directed  obliquely  inward,  and  then  vertically 
downward  ;  and  it  is  in  relation,  in  front,  with  the  tibialis  posticus  ;  lower  down,  with  the 
flexor  communis  digitorum,  which  separates  it  from  the  tibia  ;  below  that,  with  the  pos- 
terior border  of  the  internal  malleolus,  from  which  it  is  separatad  by  the  tendons  of  the 
tibialis  posticus  and  flexor  longus  digitorum  ;  still  lower,  with  the  ankle-joint ;  and,  last- 
ly, while  under  the  arch  of  the  os  calcis,  with  the  groove  for  the  tibialis  posticus.  Be- 
hind, it  is  at  first  covered  by  the  gastrocnemius  and  soleus  ;  and  in  the  lower  third  of  the 
leg,  where  these  muscles  are  wanting,  it  is  in  relation  with  the  inner  border  of  the  tendo 
Achillis,  and  is  separated  from  the  skin  by  two  fibrous  layers.  The  internal  popliteal 
nerve  runs  along  the  outer  side  of  this  artery. 

It  follows,  then,  that  the  posterior  tibial  artery  may  be  compressed  and  exposed  in  the 
whole  of  the  lower  third  of  the  leg. 

*  In  a  case  where  the  anterior  tibial,  being  very  small,  disappeared  at  the  union  of  the  two  superior  with 
the  inferior  third  of  the  leg,  the  peroneal  artery,  which  was  twice  as  large  as  the  posterior  tibial,  arose  on 
the  inside  of  this  latter  artery,  which  it  crossed  at  a  very  acute  angle,  to  become  external.  When  it  had 
reached  the  lower  third  of  the  leg,  it  passed  down  close  to  the  posterior  surface  of  the  interosseous  ligament 
which  it  traversed  at  its  inferior  portion,  and  then  formed  the  artery  of  the  foot. 


THE    INTERNAL    AND   EXTERNAL    PLANTAR  ARTERIES. 


571 


The  collateral  branches  of  the  posterior  tibial  artery  are  very  ermall,  and  do  not  require 
any  particular  description :  some  of  them  are  posterior,  and  pass  to  the  soleus  and  gas- 
trocnemius ;  others  are  anterior,  and  supply  the  deep-seated  muscles,  and  the  perios- 
teum of  the  tibia.  The  principal  nutritious  artery  of  the  tibia,  which  we  have  stated  to 
arise  from  the  tibio-peroneal  trunk,  is  often  given  off  by  the  posterior  tibial.  Most  of  the 
lower  internal  branches  perforate  the  flexor  longus  digitorum,  turn  round  over  the  inter- 
nal border  of  the  tibia,  and  ramify  in  the  periosteum  and  integuments.  Lastly,  opposite 
the  .posterior  border  of  the  lower  end  of  the  tibia,  we  find  a  small  transverse  branch, 
which  anastomoses  with  a  corresponding  branch,  already  mentioned  as  arising  from  the 
peroneal  artery. 

Beneath  the  concavity  on  the  under  surface  of  the  os  calcis,  the  posterior  tibial  gives 
off  before  its  subdivision  several  calcaneal  branches,  some  of  which  ramify  upon  the  in- 
ternal surface  of  the  os  calcis,  while  others  mount  up  above  that  bone,  apd  anastomose 
with  twigs  from  the  peroneal ;  also,  some  articular  branches  for  the  tibio-tarsal  and  as- 
tragalo-calcaneal  articulations  ;  and,  lastly,  some  branches  which  pass  up  upon  the  inner 
boixler  of  the  tarsus,  to  anastomose  with  the  internal  malleolar  artery. 

The  Internal  and  External  Plantar  Arteries. 

The  internal  and  external  plantar  arteries,  the  terminal  branches  of  the  posterior  tib- 
ial, conunence  in  the  concavity  beneath  the  os  calcis,  under  the  internal  annular  ligament 
of  the  tarsus. 

The  internal  plantar  artery  ( a,  fig.  218)  is  generally  much  smaller  than  the  external ;  it 
passes  horizontally  forward,  along  the  inner  side  of  the  sole  of  the  j^g.  218. 

foot,  between  the  abductor  poUicis  and  the  tendons  of  the  flexor 
longus  digitorum ;  more  anteriorly,  it  is  subjacent  to,  i.  e.,  farther 
from  the  skin,  than  the  flexor  brevis  digitorum ;  it  supplies  the 
muscles  ]n  question,  gives  off  several  ascending  and  oblique  branch- 
es to  the  numerous  articulations  of  the  tarsus,  anastomoses  freely 
by  some  internal  branches  with  the  internal  malleolar  and  internal 
tarsal  arteries,  and  ends  in  different  ways.  The  following  is  its  most 
common  mode  of  termination :  having  reached  the  posterior  extrem- 
ity of  the  first  metatarsal  bone,  it  divides  into  two  branches  ;  one  of 
which  is  internal,  and  runs  along  the  outer  side  of  the  abductor  pol- 
licis,  and  deviates  a  little,  so  as  to  form  the  internal  collateral  artery 
(i)  of  the  great  toe  :  the  other  is  external,  varies  much  in  size,  and 
anastomoses  (at  g)  with  the  common  trunk  of  the  collateral  arteries 
of  the  first  and  second  toe.  We  may  regard  as  its  terminating  branch 
a  cutaneous  artery,  which  perforates  the  plantar  fascia,  and  is  distrib- 
uted to  the  skin  and  sub-cutaneous  cellular  tissue  on  the  inner  side 
of  the  foot.  I  have  seen  the  internal  plantar  artery  very  small,  and 
terminating  in  the  flexor  brevis  pollicis. 

The  external  plantar  artery  (6)  forms  the  continuation  of  the  pos- 
terior tibial  in  reference  to  its  size  ;  but  in  certain  cases,  howev- 
er, it  is  not  larger  than  the  internal  plantar  arteiy.  It  passes 
obliquely  downward,  outward,  and  forward,  accompanied  by  the 
external  plantar  nerve,  under  the  os  calcis,  between  the  flexor  brevis  digitorum,  which 
is  below  or  superficial  to  it,  and  the  flexor  accessorius,  which  is  above  or  deeper :  as 
soon  as  it  gains  the  outer  border  of  the  flexor  brevis  digitorum,  upon  the  aponeurotic 
septum  between  this  muscle  and  the  abductor  of  the  little  toe,  it  turns  directly  forward, 
and  having  reached  the  under  surface  of  the  posterior  extremity  of  the  fifth  metatarsal 
bone,  it  changes  its  direction,  leaves  the  nerve,  and  curves  inward  and  forward,  towards 
the  posterior  extremity  of  the  first  interosseous  space  (at  g),  where  it  inosculates  with 
the  dorsal  artery  of  the  foot :  this  curved  portion  of  the  artery,  extending  from  the  fourth 
to  the  first  interosseous  space,  constitutes  the  plantar  arch,  which  is  formed  by  tlie  junc- 
tion of  the  dorsal  artery  of  the  foot  with  the  external  plantar  artery ;  it  runs  obliquely 
below  the  posterior  extremities,  or  sometimes  the  middle  of  the  metatarsal  bones,  be- 
tween them  and  the  adductor  of  the  great  toe,  by  which,  and  all  the  other  muscles  of 
the  middle  plantar  region,  it  is  covered  in  below ;  and  it  establishes  a  free  and  uninter- 
rupted communication  between  the  anterior  and  posterior  tibial  arteries.  I  have  seen 
the  plantar  arch  formed  exclusively  by  the  dorsal  artery  of  the  foot,  the  external  plantar 
being  very  small,  and  losing  itself  in  the  abductor  and  flexor  brevis  minimi  digiti ;  at 
other  times,  the  external  plantar  artery  only  communicates  with  the  plantar  arch  by 
means  of  some  small  branches. 

Before  it  constitutes  the  plantar  arch,  the  external  plantar  artery  gives  off  an  inferior 
calcaneal  branch  (c),  which  passes  transversely  outward,  in  front  of  the  tubercles  on  the 
lower  surface  of  the  os  calcis,  above  the  flexor  brevis  digitorum,  and  terminates  in  the 
muscles  of  the  external  plantar  region  ;  also,  some  muscular  branches  to  the  muscles  of 
the  external  plantar  region,  the  flexor  brevis  digitorum,  and  the  flexor  accessorius  ;  and, 
lastly,  some  periosteal,  osseous,  and  articular  branches,  to  Jhe  bones  and  to  the  corre- 
sponding articulations  of  the  tarsus. 


Wffi  ANGEIOLOOY. 

The  plantar  arch  itself  gives  off  superior  and  anterior  branches.  The  superior  branch- 
es, or  the  posterior  perforating  arteries,  pass  perpendicularly  upward,  through  the  poste- 
rior extremities  of  the  interosseous  spaces,  and  anastomose  with  the  dorsal  interosse- 
ous arteries.  There  are  only  three  posterior  perforating  arteries,  which  belong  to  the 
second,  third,  and  fourth  (d)  interosseous  spaces :  the  dorsal  artery  of  the  foot  repre- 
sents the  perforating  artery  of  the  first  interosseous  space. 

The  anterior  branches  are  five  in  number ;  of  these,  four  are  plantar  interosseous  or 
digital  arteries,  and  are  distinguished  by  the  numerical  names  of  first,  second,  and  third, 
proceeding  from  within  outward ;  the  fifth  anterior  branch  is  the  external  collateral  ar- 
tery of  the  little  toe. 

All  the  plantar  interosseous  or  digital  arteries  (e)  run  forward  in  the  corresponding  in- 
terosseous spaces,  and  then  between  two  of  the  metatarso-phalangal  articulations  ;  op- 
posite the  anterior  extremity  of  the  metatarsal  bone,  each  digital  artery  gives  off  a  small 
anterior  perforating  branch  (as  at  s),  which  anastomoses  with  the  corresponding  dorsal 
interosseous  artery ;  having  reached  beyond  the  posterior  extremity  of  the  first  phalan- 
ges of  the  toes  on  either  side,  each  digital  artery  divides  into  two  branches,  which  con- 
stitute the  internal  and  external  eoUateral  arteries  (/)  of  the  corresponding  toes,  and  are 
distributed  in  precisely  the  same  manner  as  the  collateral  arteries  of  the  fingers  ;  that 
is  to  say,  the  internal  and  external  collaterals  of  each  toe  anastomose  by  a  small  trans- 
verse branch  opposite  the  second  phalanx,  anastomose  again  opposite  the  middle  of  the 
last  phalanx,  and  are  almost  entirely  distributed  to  the  skin. 

The  first  plantar  interosseous  or  digital  artery  (arteria  magna  poUicis  pedis)  recjuires  a 
special  description.  It  is  very  large,  and  arises  precisely  at  the  point  {g)  where  the  dor- 
sal artery  of  the  foot  terminates  in  the  plantar  arch,  so  that  it  appears  to  result  from  the 
bifurcation  of  the  dorsal  artery  of  the  foot ;  it  passes  under  the  first  metatarsal  bone, 
and,  having  arrived  behind  the  anterior  extremity  of  that  bone,  it  gives  off  a  branch  from 
its  inner  side,  which  sometimes  forms  the  internal  collateral  artery  of  the  great  toe  ;  it 
then  passes  outward  to  reach  the  space  between  the  metatarso-phalangal  articulations 
of  the  first  and  second  toes,  and  divides  into  the  external  collateral  artery  of  the  great  toe 
{h)  and  the  internal  collateral  artery  of  the  second  toe  (/).  Opposite  the  middle  of  the  first 
phalanx  of  the  great  toe,  its  external  collateral  artery  gives  off  a  branch  inward,  which 
anastomoses  with  the  internal  collateral  artery,  and  sometimes  even  constitutes  that 
artery. 

The  external  collateral  artery  of  the  little  toe  (l),  which  may  almost  be  regarded  indiffer- 
ently as  arising  from  the  external  plantar  artery,  or  from  the  plantar  arch,  passes  for- 
ward under  the  flexor  brevis  of  the  little  toe,  and  terminates  along  the  outer  border  of 
that  toe,  by  anastomosing  with  the  tarsal  and  metatarsal  arteries  derived  from  the  dor- 
sal artery  of  the  foot.  I  have  seen  this  branch  give  origin  to  both  the  external  and  in 
temal  collateral  arteries  of  the  little  toe. 

Comparison  between  the  Arteries  of  the  Upper  and  Lower  Extremities. 

All  the  arteries  of  the  lower  extremities  are  derived  from  two  primitive  trunks,  viz., 
the  right  and  left  common  iliac  arteries,  each  of  which  soon  subdivides  into  an  internal 
and  external  iliac.  The  arteries  for  the  upper  extremities  and  head  arise  from  three 
primitive  trunks,  the  first  being  the  brachio-cephalic,  or  innominate  artery,  which  soon 
subdivides  into  the  right  common  carotid  and  right  sub-clavian ;  the  second  is  the  left 
common  carotid,  and  the  third  the  left  sub-clavian,  which  may  justly  be  regarded  as 
forming  together  a  single  primitive  trunk.  There  are,  then,  ultimately,  four  trunks  for 
the  upper  as  well  as  the  lower  parts  of  the  body. 

The  common  carotid  arteries,  distributed  as  they  are  to  the  head,  cannot  be  compared 
to  the  internal  iliacs,  which  are  given  to  the  pelvis  and  the  organs  contained  in  the  pel- 
vic cavity ;  but  as  the  pelvis  corresponds  to  the  shoulder,  we  may  find  some  analogy,  if 
not  in  origin,  at  least  in  distribution,  between  the  arteries  of  the  one  and  of  the  other. 

The  external  iliac  corresponds  to  the  sub-clavian ;  the  more  numerous  collateral 
branches  of  the  latter  are  in  part  represented  by  the  branches  of  the  internal  iliac  to  the 
walls  of  the  pelvis.  Thus,  the  os  coxae,  as  well  as  the  scapula,  is,  as  it  were,  girdled  by 
an  arterial  circle.  The  posterior  scapular  artery,  which  runs  along  the  vertebral  border 
of  the  scapula,  represents  the  circumflex  iliac,  which  turns  round  the  crest  of  the  ilium, 
and  is  distributed  to  the  muscles  of  the  abdominal  parietes  in  the  same  manner  as  the 
posterior  scapula  is  distributed  to  the  serratus  magnus  and  the  rhomboideus.  I  will  not 
carry  the  analogy  farther,  by  comparing  the  supra-scapular,  sub-scapular,  and  internal 
mammary  arteries  with  the  sciatic,  gluteal,  obturator,  and  internal  pudic. 

The  axillary  and  brachial  arteries  correspond  to  the  femoral  and  popliteal. 

The  deep  humeral  artery  represents  the  deep  femoral ;  the  circumflex  branches  of  the 
femoral  correspond  to  the  circumflex  and  sub-scapular  branches  of  the  axillary  :  the  anas- 
tomoses of  the  femoral  circumflex  arteries  with  the  obturator,  gluteal,  and  sciatic,  cor- 
respond to  the  anastomoses  of  the  circumflex  and  sub-scapular  branches  of  the  axillary 
with  the  supra-scapular  and  posterior  scapular  branches  of  the  sub-clavian. 

The  popliteal  portion  of  the  femoral  represents  that  part  of  the  brachial  which  is  sit- 


THE  VEINS.  573 

uated  opposite  the  bend  of  the  elbow ;  the  internal  and  external  collateral  arteries  deri- 
ved from  the  brachial,  together  with  the  radial,  ulnar,  and  interosseous  recurrents,  form 
anastomotic  circles  around  the  elbow,  which  are  exactly  analogous  to  those  formed  by 
the  superior  articular  arteries  given  off  from  the  popliteal  with  the  inferior  articular  ar- 
teries and  the  anterior  tibial  recurrent  artery. 

The  bifurcation  of  the  pophteal  into  the  anterior  tibial  and  the  tibio-peroneal  trunk 
represents  the  bifurcation  of  the  brachial  into  the  radial  and  ulnar :  the  anterior  tibial 
corresponds  to  the  portion  of  the  radial  situated  in  the  forearm ;  the  dorsal  artery  of  the 
foot  to  the  carpal  portion  of  the  radial ;  and  the  plantar  arch,  which  is  continuous  with 
the  dorsal  artery  of  the  foot,  represents  the  deep  palmar  arch,  which  is  the  continuation 
of  the  radial  in  the  hand. 

The  tibio-peroneal  trunk  corresponds  to  the  commencement  of  the  ulnar  artery,  the 
posterior  tibial  artery  to  the  trunk  of  the  ulnar,  and  the  peroneal  artery  to  the  interos- 
seous artery  of  the  forearm.  Just  as  the  peroneal  often  gives  origin  to  the  dorsal  ar 
tery  of  the  foot,  so  does  the  interosseous  sometimes  give  off  the  carpal  portion  of  the 
radial. 

The  plantar  arch  is  represented  by  the  deep  p^dmar  arch ;  the  plantar  interosseous  and 
the  collateral  arteries  of  the  toes,  by  the  palmar  interosseous  and  the  collateral  eirteries 
of  the  fingers. 

If  it  be  asked  why  there  is  no  superficial  plantar  arch  corresponding  to  the  superficial 
palmar  arch,  it  may  be  said,  first,  that  the  arteries  of  the  dorsum  of  the  foot  are  much 
larger  than  those  on  the  back  of  the  hand ;  and,  secondly,  that  the  hollow,  vaulted  form 
of  the  sole  of  the  foot  preserves  the  plantar  arch  from  the  compression  to  which  the  pal- 
mar arch  is  liable  in  consequence  of  the  flattened  form  of  the  hand.* 


THE  VEINS. 

Definition. — The  Venous  System. — Origin  of  the  Veins. — Course. — Anastomoses  and  Fiex- 
uses. — Varieties. — Termination. — Valves. — Structure. — Preparation. — Method  of  Descrip- 
tion. 

The  veins  (0^ei/')  are  those  vessels  which  convey  the  blood  back  from  the  extremitie& 
to  the  heart.  They  are  also  called  les  vaisseaux  a  sang  noir,  in  opposition  to  the  arteries, 
which  are  then  named  les  vaisseaux  d  sang  rouge ;  but  these  terms  are  incorrectly  appli- 
ed, for  the  pulmonary  veins  convey  red,  and  the  pulmonary  artery  black  blood. 

There  are  two  venous  systems,  corresponding  to  the  two  arterial  systems,  viz.,  the 
pulmonary  venous  system,  through  which  the  blood  returns  from  the  lungs  to  the  left  au- 
ricle, and  the  general  venous  system,  which  conveys  the  blood  from  all  parts  of  the  body 
to  the  right  auricle.  There  is  also  a  third  venous  system,  the  system  of  the  vena  porta, 
which  is  an  appendage  of  the  general  venous  system,  and,  as  we  shall  see,  forms  by  it- 
self a  perfect  circulatory  apparatus.  In  the  foetus  there  is  a  fourth  venous  system  na- 
med the  umbilical. 

General  View  of  the  Venous  System. 

Both  the  general  venous  system  and  the  pulmonary  venous  system,  regarded  as  a 
whole,  resemble  the  roots  of  a  tree,  the  trunk  of  which,  in  the  former  case,  would  cor- 
respond to  the  right  auricle,  and,  in  the  latter,  to  the  left  auricle.  While  a  single  arte- 
rial trunk,  the  aorta,  gives  origin  to  the  general  arterial  system,  the  corresponding  veins 
terminate  in  three  venous  trunks,  viz.,  the  superior  and  inferior  venae  cavae  and  the  coro- 
nary vein ;  and  so  in  the  pulmonary  venous  system  there  is  a  single  arterial  trunk,  the 
pulmonary  artery,  to  four  veins,  two  for  each  lung. 

Each  artery  has  generally  two  accompanying  veins,  which  are  called  its  satellite  veins 
{vena  comites),  and  bear  the  same  name  as  the  artery ;  besides  these,  there  exist  in  some 
parts  certain  superficial  or  sub-cutaneous  veins,  which  form  a  system  totally  apart  from  the 
arteries,  and  may  be  regarded  as  supplementary  veins. 

The  number  of  the  veins  is,  therefore,  much  greater  than  that  of  the  arteries.  This 
rule,  however,  has  some  exceptions ;  in  fact,  there  is  only  one  accompanying  vein  for 
the  great  arterial  trunks,  and  even  for  some  arteries  of  moderate  size  ;  lastly,  in  some 
few  instances,  there  is  but  one  vein  to  two  arteries.  Thus,  there  is  only  one  superior 
and  one  inferior  mesenteric,  one  renal,  and  one  external  iliac  vein,  each  of  which  cor- 
responds to  the  artery  of  the  same  name  ;  but  there  is  but  one  umbilical  vein  to  two  um- 
bilical arteries,  and  there  are  several  supra-renal  arteries,  but  only  one  supra-renal  vein. 

It  is  impossible  to  estimate  the  size  of  the  veins  with  accuracy,  in  consequence  of  the 
variations  to  which  they  are  liable  from  their  extreme  dilatability.  Hence  the  very  dif- 
ferent results  obtained  by  authors  in  this  respect.    According  to  Haller,  the  capacity  of 

*  [For  farther  information  concerning  varieties  in  the  distribution  of  arteries,  the  reader  is  referred  to  the 
"  Anatomy  of  the  Arteries,  with  its  Applications  to  Pathology  and  Operative  Sursery,"  by  Professor  R.  Qaain, 
with  drawings  by  J.  Maclise,  1841,  1842.] 


ANGEIOLOGY. 

the  veins  is  to  that  of  the  arteries  as  two  to  one  ;  according  to  Borelh,  as  four  to  one 
according  to  Sauvages,  as  nine  to  four. 

The  entire  venous  system  represents  a  truncated  cone,  the  apex  of  which  corresponds 
to  the  heart,  and  the  base  to  the  origins  of  the  veins.  From  this  disproportion  between 
the  total  area  of  the  smaller  veins,  and  the  area  of  the  trunks  in  which  they  terminate, 
it  follows  that,  in  the  course  of  the  circulation,  the  blood  passes  from  a  wider  to  a  nar- 
rower space  ;  an  arrangement  which  tends  to  accelerate  the  progress  of  the  fluid. 

The  study  of  the  veins  includes  the  consideration  of  their  origin,  course,  anastomoses, 
relations,  termination,  and  structure. 

Origin  of  the  Veins. 

The  veins  are  continuous  with  the  arteries ;  a  fact  that  is  proved  by  the  facility  with 
which  even  very  coarse  injections  will  pass  from  the  arteries  to  the  veins,  and  is  also 
most  satisfactorily  shown  by  examining  the  circulation  in  the  mesentery  of  the  frog.  In 
some  parts,  instead  of  the  communication  between  the  arteries  and  veins  being  direct, 
it  is  established  by  means  of  an  intermediate  vascular  network  or  spongy  tissue,  which 
is  entirely  venous  :  of  this  we  have  an  example  in  the  corpus  cavernosum  penis.  Last- 
ly, the  facihty  with  which  injections  forced  into  the  veins  from  the  trunks  towards  the  ex- 
tremities escape  upon  the  surface  of  the  mucous  membranes,  would  seem  to  establish 
the  fact  of  these  vessels  arising  by  open  mouths  at  the  surface  of  those  membranes. 
HaUer  admitted  the  existence  of  absorbent  veins  arising  from  all  the  free  surfaces.* 

Course. 

Immediately  after  their  origin,  the  veins  form  networks,  from  which  small  branches 
are  given  off  to  anastomose  together  and  form  larger  and  larger  networks  :  from  these, 
again,  proceed  larger  branches,  which  become  successively  united,  just  as  the  arteries 
are  successively  divided ;  that  is  to  say,  the  smaller  branches  unite  to  form  larger  ones, 
and  these  still  larger  branches,  which  are  at  length  united  into  the  venous  trunks.  In 
the  limbs,  the  veins  are  divided  into  the  superficial  and  the  deep.  The  deep  veins,  which 
accompany  the  arteries,  have  similar  relations  with  the  bones,  muscles,  nerves,  fasciae, 
and  skin,  as  those  vessels.  The  deep  veins  are  always  in  contact  with  the  arteries, 
and  are  contained  in  the  same  fibrous  sheaths.  All  attempts  to  ascertain  any  law  by 
which  the  relations  of  the  veins  with  the  arteries  are  regulated  have  been  unsuccessful. 
Indeed,  the  relative  position  of  the  two  kinds  of  vessels,  although  constant,  does  not 
seem  to  follow  any  general  rule.  The  close  relations  between  the  arteries  and  veins, 
interesting  as  they  are  to  the  surgeon,  who  is  required  to  separate  the  veins  carefully 
from  an  artery  before  tying  the  latter,  are  no  less  so  to  the  physiologist.  The  shock 
communicated  to  the  blood  in  the  venae  comites  by  the  pulsations  of  their  correspond- 
ing artery,  must  assist  the  circulation  of  that  fluid.  In  some  cases  of  hypertrophy  of  the 
heart,  I  have  seen  the  blood  issue  in  jets  from  a  vein  as  if  it  were  from  an  artery. 

When,  as  it  in  some  places  happens,  the  deep  veins  do  not  accompany  the  arteries, 
there  is  always  some  special  roason  which  observation  may  determine.  For  example, 
the  cerebral  sinuses,  which  are  really  veins,  do  not  accompany  the  arteries  ;  nor  are  the 
hepatic  veins,  the  ophthahnic  vein,  and  the  vena  azygos,  satellites  of  their  correspond- 
ing arteries. 

The  superficial  veins  exist  only  in  parts  where  the  circulation  in  the  deep  veins  is  liable 
to  be  obstructed  during  the  exercise  of  those  parts.  In  fact,  as  the  venous  blood  does 
not  circulate  like  the  arterial,  under  the  influence  of  an  impelling  agent  directly  connected 
with  them,  it  is  retarded  by  the  slightest  cause,  and  hence,  therefore,  the  necessity  foi 
additional  means  of  circulation. 

The  superficial  veins,  therefore,  constitute,  in  reference  to  the  deep  veins,  a  collateral 
route  for  the  venous  blood,  especially  during  the  contraction  of  the  muscles  of  the  uppei 
and  lower  extremities,  as  we  find  in  persons  who  exercise  their  limbs  much.  I  have 
shown  that  the  tongue,  as  well  as  the  extremities,  is  provided  with  a  superficial  and  a 
deep  set  of  veins.  The  superficial  veins  are  situated  between  the  investing  aponeuroses 
of  the  muscles  and  the  skin,  from  which  they  are  separated  by  a  very  thin  layer  of  fascia : 
they  are  accompanied  by  the  sub-cutaneous  nerves  and  lymphatics. 

From  this  description  it  follows,  that  such  of  the  deep  veins  as  accompany  the  arteries 
do  not  require  any  special  description,  because  they  have  the  same  distribution  and  the 
general  relations  as  the  arteries  :  the  description  of  the  venous  system  will  therefore  be 
confined  to  an  examination  of  such  veins  as  pursue  a  course  independent  of  that  of  the 
arteries. 

Anastomoses  and  Plexuses. 
The  anastomoses  of  the  veins  are  more  numerous  than  those  of  the  arteries,  and  they 
take  place  by  means  of  much  larger  vessels ;  an  arrangement  which  compensates  for 
the  want  of  an  impelling  organ  directly  connected  with  them.     Thus,  anastomoses  by 

*  [The  eseapfi  of  injections  upon  mucous  membranes  is  due  to  rupture  or  transudation ;  the  existence  oJ 
veins  having  open  mouths  tipon  these  or  other  free  surfaces  is  now  denied  by  the  best  authorities.! 


THE    VEINS.  575 

direct  inosculation,  by  lateral,  transverse,  or  oblique  communications,  and  anastomoses 
by  convergence,  are  found  in  every  situation,  and  with  all  conceivable  varieties.  The 
branches  of  the  veins  form  lozenge-shaped  meshes ;  and  both  the  trunks  and  the  branches 
communicate  freely  with  each  other ;  that  is  to  say,  the  superficial  with  the  deep  set,  the 
veins  of  the  superficial  set  and  those  of  the  deep  set  among  each  other,  and  the  vena 
cava  superior  with  the  vena  cava  inferior ;  so  that  we  may  say  that  the  whole  venous 
system  forms  one  vascular  network,  and  it  is  by  these  free  communications  that  such 
obstacles  as  impede,  or  even  completely  intercept  the  course  of  the  blood  in  a  given  part, 
are  rendered  incapable  of  stopping  it  altogether.  In  order  to  intercept  the  course  of  the 
venous  blood  completely,  it  would,  in  fact,  be  necessary  to  obliterate,  not  only  the  prin- 
cipal trunk,  but  also  all  the  collateral  channels.  One  remaAable  mode  of  anastomosis 
is  the  following :  a  collateral  vein  arises  from  some  point  of  a  particular  vein,  and  termi- 
nates at  a  greater  or  less  distance  in  the  same  vein,  like  a  canal  intended  to  unite  two 
distant  points  of  the  same  stream ;  this  collateral  channel  is  intended  to  receive  a  num- 
ber of  veins,  which  would  otherwise  have  terminated  in  the  principal  vessel.  The  fol- 
lowing is  a  variety  of  this  kind  of  anastomosis  :  one  vein  divides  into  two  of  equal  size, 
which  diverge  from  each  other  at  a  very  acute  angle,  or,  rather,  run  parallel,  and  reunite 
at  a  greater  or  less  distance.    The  saphenous  vein  often  presents  this  arrangement. 

A  venous  plexus,  which  consists  of  a  complicated  network  of  vessels,  is  nothing  more 
than  the  highest  development  of  an  anastomosis :  venus  plexuses  are  found  in  parts 
where  the  circulation  is  liable  to  be  retarded,  or  in  organs  whose  functions  require  a  large 
aflJux  of  blood  ;  example,  the  vesical,  uterine,  and  spermatic  plexuses. 

The  veins  are  rarely  tortuous,  like  the  arteries,  but  are  generally  straight ;  a  circum- 
stance which  also  helps  to  lessen  the  effects  of  the  deficiency  of  a  direct  impelling  organ ; 
for  tortuosities,  by  multiplying  the  points  of  friction,  would  evidently  retard  the  flow  of 
blood  in  the  veins.  The  great  veins  are  not  at  all  tortuous,  but  the  smallest  veins,  and 
those  forming  the  plexuses,  are  distinctly  so.  The  tortuosities  of  veins  are  generally 
regarded  as  the  result  of  their  too  great  development.  Thus,  hypertrophied  veins, 
whether  varicose  or  not,  always  pursue  a  distinctly  zigzag  course. 

Varieties. 

The  varieties  in  the  size,  the  anastomoses,  and  the  terminations  of  the  veins  are  so 
numerous,  that  it  is  impossible  to  include  them  in  any  general  description  ;  it  would  seem 
that,  for  the  due  performance  of  its  function,  it  matters  not  whether  a  vein  terminates  in 
one  or  another  part  of  the  venous  system.  It  may  be  readily  conceived  that  as  the  an- 
astomoses of  the  veins  are  very  numerous,  and  take  place  by  very  large  branches,  it  can 
be  of  little  consequence  which  of  those  anastomotic  branches  predominates. 

Terminaiion. 
The  veins  of  all  the  supra-diaphragmatic  portion  of  the  body  terminate  in  the  vena 
cava  superior ;  the  veins  of  the  sub-diaphragmatic  portion  terminate  in  the  vena  cava 
inferior  ;  the  veins  of  the  heart  terminate  separately  in  the  auricle  ;  the  two  venae  cavae 
communicate  with  each  other  through  the  vena  azygos,  and  especially  through  the  veins 
of  the  spinal  canal,  so  that  when  either  of  them  is  obliterated  the  other  supplies  its  place. 

Valves. 

The  existence  of  membranous  folds,  or  valves  (a  a.  Jig.  218*),  in  the  interior  of  the 
veins  is  one  of  the  most  characteristic  features  in  their  structure.  p^    218  * 

The  existence  of  these  valves  is  shown  externally  in  injected  veins 
by  a  more  or  less  distinct  knotted  appearance. 

If  we  open,  under  water,  a  vein  provided  with  valves,  we  perceive 
attEiched  to  its  interior  surface  certain  membranous  folds,  or  mem- 
branous processes,  as  they  were  named  by  Charles  Etienne,  who 
appears  to  have  discovered  them  ;  there  are  generally  two,  placed  one 
opposite  the  other ;  they  are  rarely  solitary  even  in  the  smallest  ves- 
sels, and  still  less  commonly  are  three  found  together,  as  Haller  and 
Morgagni  say  they  have  observed.  They  all  have  a  semilunar  form, 
like  the  sigmoid  valves  of  the  aorta  and  pulmonary  artery ;  their  ad- 
herent border  is  convex,  and  directed  towards  the  extremities  ;  their 
free  border  is  straight,  and  is  directed  towards  the  heart. 

Both  surfaces  are  free  ;  the  inferior  is  turned  towards  the  centre 
of  the  vessel,  while  the  superior  corresponds  to  its  sides,  which  al- 
ways present  a  dilatation  or  sinus  (i)  opposite  the  valves,  that  gives 
a  knotted  appearance  to  the  vein  when  distended ;  the  constricted 
part  of  the  vein  corresponds  to  the  adherent  border  of  the  valve,  and 
the  dilated  portion  to  the  valve  itself 

As  a  necessary  consequence  of  their  direction,  the  valves  permit  the  blood  to  flow 
from  the  extremities  towards  the  heart,  but  prevent  its  course  in  the  opposite  direction ; 
it  was  this  anatomical  fact  which  led  Harvey  to  the  discovery  of  the  course  of  the  venous 


SW  ANGEIOLOGY. 

blood.  The  valves  are  so  long,  that  when  tvv'o  opposite  ones  are  depressed,  they  almost 
completely  close  the  channel  of  the  vessel. 

Notwithstanding  their  tenuity,  the  valves  are  extremely  strong  :  a  fact  of  which  we 
may  be  easily  convinced  by  endeavouring  to  inject  the  veins  in  the  opposite  direction  to 
that  in  which  the  blood  flows  through  them.  The  perforations  and  notches  sometimes 
observed  in  the  valves  of  veins  appear  to  me  to  be  accidental. 

The  office  of  the  valves  is  to  prevent  that  retrograde  movement  in  the  course  of  the 
blood  which  would  otherwise  occur  from  so  many  causes. 

All  veins  are  not  provided  with  valves,  and  those  which  have  them  are  very  unequally 
so.  It  may  be  said  that  their  presence  and  their  number,  their  proximity,  and  their  dis- 
tance from  each  other,  are  directly  influenced  by  the  degree  of  opposition  to  the  onward 
progress  of  the  blood  in  any  set  of  veins :  thus,  the  v^ves  are  more  numerous  in  the 
veins  of  the  limbs  where  the  blood  flows  against  its  own  gravity  than  in  those  parts 
where  it  follows  the  direction  of  gravitation.  There  are  no  vedves  in  the  system  of  the 
vena  portaj.    They  are  generally  more  numerous  in  the  deep  than  in  the  superficial  veins. 

We  always  find  a  pair  of  valves  at  the  termination  of  a  vein  in  a  larger  trunk.  Very 
small  veins  have  no  valves.  I  shall  take  care  to  describe  the  number  and  arrangement 
of  the  valves  in  the  principal  veins. 

The  number  of  the  valves  is  subject  to  many  varieties.  Some  valves  completely,  and 
others  but  imperfectly  intercept  the  course  of  the  blood. 

Structure. 

In  structure,  a  vein  appears  to  me  to  resemble  an  artery,  without  its  middle  coat.*  In 
fact,  even  by  the  most  careful  examination,  we  can  only  distinguish  two  coats  in  a  vein ; 
an  external,  called  the  cellular  coat,  but  which  I  believe  to  be  of  the  same  nature  as  the 
dartos,  and  an  internal  coat,  very  thin,  which  is  analogous  to  the  lining  membrane  of  the 
arteries,  and,  therefore,  resembles  the  serous  membranes.  The  internal  membrane  is 
the  essential  constituent  of  a  vein ;  for  the  external  coat  may  be  wanting,  or  its  place 
may  be  supplied  by  some  other  tissue  :  thus,  in  the  sinuses  of  the  dura  mater,  in  the  cells 
of  the  corpora  cavernosa  penis,  in  the  substance  of  the  walls  of  the  uterus,  and  in  the 
venous  canals  of  bones,  the  place  of  the  external  membrane  is  supplied  by  the  dura  mater, 
by  the  fibrous  parietes  of  the  cells  of  the  corpora  cavernosa,  by  the  tissue  of  the  uterus 
itself,  and  by  the  proper  substance  of  the  bones. 

The  valves  are  formed  by  a  fold  of  the  internal  membrane,  containing  some  fibrous 
filaments,  which  are  found  especially  along  their  adherent  border. 

The  existence  of  a  middle  coat  in  the  veins  is  admitted  by  authors,  some  of  whom 
say  it  is  composed  of  longitudinal  fibres,  while  others  think  it  consists  of  circular  fibres  ; 
but  such  fibres  do  not,  in  reality,  exist.  Vesalius  relates  that,  wishing  to  show  them  at 
one  of  his  lectures,  he  was  obliged  to  confess  that  he  had  never  seen  them,  and  could 
not  find  them.t 

The  walls  of  the  veins  are  themselves  supplied  with  small  arteries  and  veins  {vasa,  vaso- 
rum).  No  nerves  have  been  demonstrated  in  them,  nor  do  either  mechanical  or  chem- 
ical stimuli  applied  to  the  inner  membrane  of  the  veins  occasion  pain. 

It  is  rather  a  remarkable  fact,  in  reference  to  the  relations  of  the  veins  with  the  nerves, 
that  nervous  plexuses  are  never  supported  by  veins,  but,  on  the  contrary,  seem  always 
to  be  separated  from  them.    The  trunk  of  the  vena  portas  is  the  only  exception. 

Pr  ^oration. 

Most  of  the  veins  above  a  certain  size  may  be  examined  without  being  previously  in- 
jected ;  but  injections  are  necessary  for  their  minute  investigation.  The  arrangement 
of  the  valves,  which,  in  general,  oppose  the  transmission  of  liquids  from  the  heart  to- 
wards the  extremities,  renders  it  necessary  to  inject  a  great  number  of  veins  from  their 
extremities  towards  the  heart.  In  general,  in  order  to  obtain  as  perfect  an  injection  as 
possible,  it  is  necessary  to  throw  in  the  fluid  simultaneously  at  several  points  and  in  sev- 
eral directions.  Thus,  a  pipe  may  be  placed  in  the  vena  cava  superior,  into  which  the 
injection  should  be  pushed  from  the  heart  towards  the  extremities ;  another  in  the  upper 
part  of  the  cephalic  or  basilic  vein  of  the  right  side ;  a  third  in  the  dorsal  vein  of  the  left 
thumb  ;  a  fourth  in  the  right  femoral  vein ;  and,  lastly,  one  in  the  left  internal  saphenous 
vein.  In  all  these  vessels,  excepting  in  the  vena  cava,  the  injection  should  be  thrown 
from  the  extremities  towards  the  heart. 

The  injection  of  the  veins  from  the  arteries,  which  was  proposed  by  Jankius,  is  doubly 

♦  [The  walls  of  a  vein  are  thinner  than  those  of  an  artery ;  and  hence  the  former,  when  cut  across,  docs  not 
remain  patent,  like  the  latter  kind  of  vessel.  The  coats  of  tlie  superficial  veins  are  thicker  than  those  of  the 
deep-seated  ones,  especially  in  the  lower  limbs.] 

t  [Nevertheless,  the  veins  have  an  intermediate  set  of  fibres,  constituting  a  thin  middle  coat.  The  external 
coat  is  thinner  than  that  of  the  arteries,  and  consists  of  interlaced  cellular  filaments.  The  middle  coat,  differ- 
ing from  that  of  an  artery,  is  composed  of  pale  red  filaments,  like  those  of  cellular  tissue,  miied  with  others 
resembling  elastic  tissue  ;  the  bundles  into  which  these  filaments  are  collected  pursue  a  very  irregular  course 
around  the  vein.  The  internal  coat  is  more  distinct,  less  brittle,  and  more  readily  detached  than  the  corre- 
sponding- arterial  tissue  :  it  consists  of  fine  longitudinal  interlacing  filaments,  covered  with  an  epithelium  ;  it 
is  continuous  with  the  lining  membrane  of  the  auricles.] 


THE    PULMONARY    VEINS.  15*S^ 

inconvenient ;  first,  because  both  veins  and  arteries  would  be  coloured  alike,  which  would 
make  it  difficult  to  distinguish  between  them ;  and,  secondly,  because  we  must  use  a 
very  thin  liquid,  which  would  not  become  firm. 

The  most  convenient  injection  mass  is  a  coloured  glue-size,  because  it  sets  slowly. 
If  tallow  be  used,  the  subject  must  be  placed  in  warm  water. 

The  dissection  of  the  veins,  as  well  as  that  of  the  arteries,  consists  in  separating  them 
from  surrounding  parts,  and  preserving  their  relations  as  much  as  possible. 

Method  of  Description, 
In  describing  the  veins,  we  may  either  follow  the  course  of  the  blood,  ana  trace  the 
veins  from  the  extremities  to  the  heart,  or  we  may  pursue  an  opposite  direction,  and 
trace  them  from  the  heart  to  the  extremities.  I  shall  adopt  a  combination  of  the  two 
methods ;  that  is  to  say,  I  shall  commence  with  the  trunks,  and  pass  in  succession  to 
the  larger  and  then  to  the  smaller  branches ;  but  in  the  particular  description  of  each 
vein,  I  shall  consider  it  as  originating  at  the  point  most  remote  from,  and  terminating  at 
the  point  nearest  to,  the  heart. 


DESCRIPTION  OF  THE  VEINS. 

THE  PULMONARY  VEINS. 
Preparation. — Description. — Relations. — Size. — Peculianttes. 

Preparation. — These  veins  may  be  traced  from  the  heart  towards  their  terminations 
The  facility  with  which  injections  pass  from  the  pulmonary  arteries  into  the  pulmonary 
veins  should  be  borne  in  mind. 

There  are  four  pulmonary  veins  (I  l,m  m,fig.  171),  two  for  each  lung,  which  open  sep- 
arately into  the  left  auricle.  Not  unfrequently,  however,  there  are  five ;  three  for  the 
right,  and  two  for  the  left  lung.  Sometimes  the  two  left  puhnonary  veins  seem  to  unite 
immediately  before  opening  into  this  auricle. 

The  trunks  of  these  veins,  each  of  which  corresponds  to  a  lobe  of  the  lung,  pass  out 
of  that  organ  in  front  of  the  corresponding  pulmonary  artery.  The  two  upper  veins  of 
the  right  lung  generally  unite  into  a  single  trunk,  which  descends  towards  the  root  of 
the  lung,  while  the  inferior  trunk  runs  horizontally.  In  the  interior  of  each  lobule,  the 
pulmonary  veins  coimnence  from  the  ultimate  ramifications  of  the  pulmonary  artery,  and 
unite  into  a  single  branch,  which  emerges  from  the  lobule  in  contact  with  the  corre- 
sponding artery.  These  venous  branches  successively  unite,  so  as  to  form  a  single 
trunk  for  each  lobe  of  the  lung.  There  are,  therefore,  three  trunks  for  the  right  lung 
and  two  for  the  left ;  but  the  trunk  from  the  middle  lobe  of  the  right  lung  soon  unites  to 
that  from  the  upper  lobe.  The  pulmonary  trunk  belonging  to  the  upper  lobe  lies  in  front 
of  that  belonging  to  the  lower  lobe ;  it  also  passes  obliquely  downward  and  outward, 
while  that  which  belongs  to  the  lower  lobe  runs  horizontally.  These  four  trunks  open 
into  the  four  angles  of  the  left  auricle  (n),  after  having  perforated  the  pericardium,  with- 
in the  cavity  of  which  their  course  is  exceedingly  short. 

Relations. — In  the  substance  of  the  lungs  the  branches  of  the  veins  are  behind,  those 
of  the  arteries  are  in  front,  and  the  bronchia  are  in  the  middle.  The  larger  branches  of 
these  three  kinds  of  vessels  cross  each  other  at  acute  angles,  but  their  extreme  ramifi- 
cations are  parallel.  At  the  root  of  the  lung,  the  veins  are  in  front,  the  artery  is  in  the 
middle,  and  the  bronchus  behind. 

In  the  pericardium,  the  anterior  surface  of  the  veins  is  invested  by  the  serous  layer 
of  the  pericardium.  The  right  pulmonary  veins  are  in  relation,  in  front,  with  the  vena 
cava  superior,  which  crosses  them  at  right  angles :  the  left  puhnonary  veins  are  in  re 
lation  with  the  left  pulmonary  artery. 

It  is  generally  said  that  the  pulmonary  artery  is  larger  than  the  pulmonary  veins ;  but 
it  has  appeared  to  me  that  the  pulmonary  veins  are  no  exception  to  the  general  rule  that 
the  veins  are  larger  than  their  corresponding  arteries. 

Moreover,  although  there  are  two  pulmonary  venous  trunks  for  each  lung,  by  a  re- 
markable exception  only  a  single  vein  accompanies  each  branch  of  the  artery. 

The  pulmonary  veins  have  no  valves,  even  at  their  openings  into  the  auricle ;  they 
carry  red  blood  like  the  arteries,  and  hence  the  name  arteria.  venosce,  by  which  they  were 
designated  by  the  ancients.  Distinctly  circular  muscular  fibres  can  be  traced  upon  the 
portion  of  the  pulmonary  veins  situated  within  the  pericardium.  The  serous  layer  only 
partially  invests  these  veins,  and  it  is  doubtful  whether  the  fibrous  layer  is  prolonged. 
upon  them  at  all. 


THE  VEINS  OF  THE  HEART. 

The  Great  Coronary  or  Cardiac  Vein. — The  Small  Cardiac  Veins. 
The  cardiac  veins  are  divided  into  the  great  coronary  vein  and  the  small  coronary 
veins  of  the  heart. 

4D 


S78  ANGEIOLOGY. 

The  great  coronary  vein  commences  near  the  apex  of  the  heart,  at  the  lower  part  of 
the  anterior  inter-ventricular  furrow,  up  which  it  runs  (e,  fig.  191),  gradually  increasing 
in  size  ;  having  arrived  at  the  base  of  the  ventricle,  it  turns  to  the  left,  so  as  to  leave  the 
anterior  coronary  artery,  and,  changing  its  direction,  it  runs  along  the  left  auriculo- ven- 
tricular furrow,  becoming  larger  as  it  proceeds,  and  at  length  opens  (e,fig.  192)  into  the 
posterior  and  inferior  part  of  the  right  auricle,  near  the  inter-auricular  septum. 

The  very  great  size  of  that  portion  of  the  vein  which  embraces  the  left  auriculo-ven- 
tricular  furrow  has  obtained  for  it  the  name  of  the  coronary  venous  sinus.  It  almost  always 
presents  a  very  remarkable  dilatation,  or  ampulla,  before  it  enters  the  auricle.  During 
its  course  it  receives  a  great  number  of  branches. 

Thus,  its  vertical  or  ascending  portion  receives  both  superficial  and  deep  veins,  which 
emerge  from  the  adjacent  parts  of  the  ventricles  and  their  intervening  septum. 

Its  circular  portion  receives  some  small  descending  or  auricular  branches  from  the  left 
auricle,  and  also  larger  ascending  or  ventricular  branches,  which  enter  it  at  right  angles ; 
among  the  latter,  we  find  the  vein  of  the  left  border  of  the  heart,  which  commences  near 
the  apex  of  the  left  ventricle,  runs  backward,  crossing  obliquely  over  the  corresponding 
artery,  and  opens,  almost  at  a  right  angle,  into  the  great  coronary  vein,  behind  the  left 
border  of  the  heart ;  secondly,  two  or  three  branches  from  the  posterior  surface  of  the 
left  ventricle  ;  and,  lastly,  a  posterior  inter-ventricular  branch,  which  traverses  the  poste- 
rior inter-ventricular  furrow,  and  terminates  in  the  ampulla,  at  the  opening  of  the  coro- 
nary vein  into  the  right  auricle.  I  have  seen  this  branch  terminate  at  once  in  the  auri- 
cle by  a  distinct  opening,  covered  or  protected  by  the  valve  of  the  coronary  vein.  A 
small  vein  which  runs  along  the  posterior  half  of  the  right  auriculo-ventricular  furrow 
opens  directly  into  the  right  auricle,  near  the  ampulla  of  the  great  coronary  vein  :  I  do 
not  know  whether  this  small  vein  is  constant.  The  great  coronary  vein  has  no  valves, 
excepting  at  its  entrance  into  the  right  auricle,  where  the  valve,  however,  cannot 
completely  oppose  the  reflux  of  the  blood,  for  the  great  coronary  vein  is  always  filled 
when  an  injection  is  thrown  into  the  vena  cava  superior. 

The  small  or  anterior  coronary  veins  of  the  heart,  or  small  cardiac  veins  {vence  innomi- 
nate of  Vieussens),  consist  of  three  or  four  small  veins,  which  run  upon  the  anterior 
surface  of  the  right  ventricle,  and  open  at  the  lower  part  of  the  right  auricle.  Among 
them  we  may  point  out  one  which  runs  along  the  right  border  of  the  heart,  and  has  been 
CEdled  the  vein  of  Galen ;  and  also  another  very  small  one,  which  commences  upon  the 
infundibuliform  prolongation  of  the  right  ventricle,  enters  the  right  auriculo-ventricular 
furrow,  and  opens  directly  into  the  right  auricle. 

It  follows,  then,  that  the  small  cardiac  veins  belong  to  the  front  of  the  right  ventricle 
and  auricle,  or,  we  might  even  say,  to  the  greater  part  of  the  right  side  of  the  heart; 
while  the  great  coronary  vein  belongs  to  the  left  side  of  the  heart,  and  to  the  remaining 
part  of  the  right  side. 

I  have  already  said  that  the  veins  of  Thebesius,  or  vena  minima,  which  are  described 
by  Vieussens,  Thebesius,  and  Lancisi,  and  which  are  said  to  pour  their  contents  into  all 
the  cavities  of  the  heart,  do  not  exist  at  aU,  and  that  their  supposed  orifices  are  nothing 
more  than  culs-de-sac,  formed  by  intervals  between  the  muscular  fasciculi  of  the  heart, 
and  at  the  bottom  of  which  an  areolar  structure  is  seen.  I  agree  with  Senac  in  admit- 
ting the  existence  of  venous  openings  in  the  right  auricle  only  (of  course  excepting  those 
of  the  pulmonary  veins) 


THE  SUPERIOR,  OR  DESCENDING  VENA  CAVA  AND  ITS  BRANCHES. 

The  Superior  Vena  Cava. — The  Brachio-cephalic  Veins — the  Inferior  Thyroid — the  Internal 
Mammary — the  Superior  Phrenic,  the  Thymic,  Pericardiac,  and  Mediastinal — the  Verte- 
bral.— The  Jugular  Veins,  viz.,  the  External — the  Anterior — and  the  Internal. — The  En- 
cephalic Veins,  and  the  Sinuses  of  the  Dura  Mater,  viz.,  the  Lateral — the  Superior  Lon- 
gitudinal— the  Straight — the  Superior  and  Inferior  Petiosal — the  Cavernous — the  Coro- 
nary— and  the  Anterior  and  Posterior  Occipital  Sinuses — the  Conflux  of  the  Sinuses. — 
jyie  Branches  of  Origin  of  the  Jugular  Veins — the  Facial — the  Temporo-maxillary — the 
Posterior  Auricular — the  Occipital — the  Lingual — the  Pharyngeal — the  Superior  and  Mid- 
dle Thyroid — the  Veins  of  the  Diplo'e. — Summary  of  the  Distribution  of  the  Veins  of  the 
Head. — The  Deep  Veins  of  the  Upper  Extremity — the  Palmar,  Radial,  Ulnar,  Brachial, 
and  Axillary — the  Sub-clavian. — The  Superficial  Veins  of  the  Upper  Extremity — in  the 
Hand — in  the  Forearm — at  the  Elbow — aiid  in  the  Arm. — General  Remarks  en  these  Su- 
perficial Veins. 

The  vena  cava  superior,  descenden^,  is  the  common  trunk  of  all  the  veins  of  the  upper 
naif  of  the  body,  and  very  nearly  corresponds  to  the  ascending  aorta  in  the  parts  to 
which  it  is  distributed.  It  is  situated  to  the  right  of  the  sternum,  within  the  thorax,  and 
hence  has  been  named  the  thoracic  vena  cava ;  it  commences  immediately  below  the  car- 
tilage of  the  first  rib  on  the  right  side,  where  it  is  formed  by  the  junction  of  the  two 
brachio-cephahc  veins  (c  c',  fig.  1 701.  which  return  the  blood  from  the  whole  supra-dia* 


679 

pbragmatic  portion  of  the  body :  from  the  point  above  mentioned  it  descends  vertically, 
describing  a  slight  curve,  the  concavity  of  which  is  turned  to  the  left,  and  the  convexity  ■ 
to  the  right  side  ;  it  enters  the  pericardium,  and  (d,figs.  191,  193)  opens  into  the  upper 
part  of  the  right  auricle  (m  h,  Jig.  193)  behind  the  auricula ;  its  posterior  half  appears  to 
be  continuous  with  the  corresponding  part  of  the  vena  cava  inferior:  hence,  doubtless, 
arose  the  opinion  of  Vesalius,  that  there  is  but  one  vena  cava. 

Its  relations,  while  without  and  within  the  pericardium,  require  to  be  separately  ex- 
amined. Externally  to  the  pericardium,  the  vena  cava  superior  is  in  relation  with  the 
right  lung,  being  separated  from  it,  however,  by  the  right  wall  of  the  mediastinum,  and 
by  the  phrenic  nerve,  which  is  at  first  on  the  outer  side,  and  then  passes  in  front  of  the 
vein  ;  on  the  left  side,  it  is  in  relation  with  the  arch  of  the  aorta ;  in  front,  with  the  re- 
mains of  the  thymus  gland  and  the  cellular  tissue  of  the  mediastinum,  by  which  it  is 
separated  from  the  sternum ;  behind,  with  the  trachea,  a  great  number  of  lymphatic 
glands  intervening  between  them. 

Within  the  pericardium  the  vena  cava  is  covered  by  the  serous  layer  of  that  membrane 
in  its  anterior  three  fourths  :  it  is  in  immediate  contact  behind  with  the  right  pulmonary 
artery  and  right  superior  pulmonary  vein  ;  on  the  left  side,  it  is  merely  in  contact  with 
the  aorta. 

The  superior  vena  cava  has  no  valves,  either  in  its  course  or  at  its  opening :  it  follows, 
therefore,  that  each  contraction  of  the  auricle  is  accompanied  by  a  regurgitation  of  blood 
into  the  vena  cava  and  into  the  branches  immediately  opening  into  it.  Upon  this  regm- 
gitation  depends  the  phenomenon  of  venous  pulsation. 

The  vena  cava  presents  certain  conditions  in  its  structure  which  require  special  notice. 
It  has  been  said  that  the  muscular  fibres  of  the  auricle  are  prolonged  upon  it ;  I  can  state 
that  such  is  not  the  case.  The  serous  layer  of  the  pericardium  covers  the  pericardial 
portion  of  this  vein,  and  the  fibrous  layer  is  prolonged  upon  that  part  of  the  vessel  which 
is  external  to  the  pericardium. 

Lastly,  the  relative  length  of  the  intra-  and  extra-pericardial  portions  of  the  vena  cava 
is  subject  to  much  variety :  sometimes  the  vein  enters  the  pericardium  at  about  the  mid- 
dle of  its  course  ;  sometimes  only  a  few  lines  from  its  termination  in  the  auricle. 

The  caliber  of  the  vena  cava  superior  is  less  than  that  of  both  the  brachio-cephalic 
trunks  taken  together,  and  also  less  than  that  of  the  vena  cava  inferior.  Its  length  va- 
ries from  two  and  a  half  to  three  inches. 

Sometimes  this  vein  is  double  :  I  once  found  in  an  adult  two  superior  cavae,  opening 
into  the  right  auricle,  a  variety  which  evidently  depended  upon  the  two  brachio-cephalic 
veins  not  having  united.     This  condition  is  normal  in  several  animals. 

Collateral  Veins. — The  vena  cava  superior  receives  no  branch  while  within  the  pericar- 
dium, immediately  before  entering  which  it  receives  the  vena,  azygos.  The  right  inferior 
thyroid  and  internal  mammary  veins,  and  the  small  veins  called  thymic,  pericardiac,  medias- 
tinal, and  right  superior  phrenic,  generally  enter  opposite  the  junction  of  the  two  brachio- 
cephalic trunks,  and  not  into  the  vena  cava  itself 

As  the  vena  azygos  forms  part  of  the  system  of  spinal  veins,  it  will  be  described  with 
them. 

As  the  other  veins  have  a  similar  distribution  on  both  sides,  the  description  of  those 
on  the  left  side  will  apply  to  those  of  the  right  also. 

The  Brachio-cephalic  Veins. 

The  brachio-cephalic  veins,  or  vencE  innominatts  of  Meckel  {cc',jig.  170),  which  are  gen- 
erally included  in  the  description  of  the  sub-clavian  vein,  correspond  exactly  to  the  bra- 
chio-cephalic or  innominate  artery,  being  fonned  by  the  union  of  the  internal  jugular 
vein  {d)  and  the  sub-clavian  vein  (e),  properly  so  called,  which  correspond  to  the  common 
carotid  and  the  sub-clavian  arteries. 

There  are  two  brachio-cephalic  veins,  one  for  the  right  (c')  and  one  for  the  left  side 
(c) ;  so  that  the  arrangement  of  the  veins  of  the  upper  half  of  the  body  is  more  sym- 
metrical than  that  of  the  arteries. 

The  right  and  left  venous  trunks  differ  from  each  other  in  length ;  for  as  they  both 
commence  at  the  junction  of  the  corresponding  internal  jugular  and  sub-clavian  veins, 
opposite  the  sternal  end  of  the  clavicle  of  their  own  side,  and  terminate  on  the  right  of 
the  median  hue,  to  form  the  commencement  of  the  vena  cava  superior,  it  follows,  therefore, 
that  the  right  brachio-cephalic  vein  must  be  much  the  shorter  ;  it  is,  in  fact,  only  from 
twelve  to  fourteen  lines  in  length,  while  that  of  the  left  side  is  twice  as  long. 

They  differ  also  in  caliber,  the  left  brachio-cephahc  trunk  being  much  larger  than  the 
right,  in  consequence  of  receiving  the  internal  mammary  and  inferior  thyroid  veins  of  its 
own  side. 

Also  in  direction,  the  right  being  almost  vertical,  and  sloping  only  slightly  to  the  left 
side  as  it  descends,  like  the  superior  vena  cava,  which  follows  the  very  same  direction ; 
the  left  vein,  on  the  contrary,  is  almost  horizontal,  and  describes  a  curve  with  its  con- 
cavity directed  backward ;  the  two  brachio-cephahc  veins,  therefore,  unite  at  a  right 
angle  to  form  the  vena  cava. 


580  ANGEIOLOGY. 

Lastly,  they  have  different  relations.  Tlie  concavity  of  the  left  vein  embraces  the 
front  of  the  highest  part  of  the  aortic  arch,  and  the  three  great  arteries  arising  from  it. 
It  coiTesponds  anteriorly  veith  the  sternal  extremity  of  the  left  clavicle  and  the  sterno- 
clavicular articulation,  and  runs  along  the  upper  border  of  the  sternum.  The  right  vein 
is  situated  in  the  right  cavity  of  the  thorax  ;  it  is  parallel  with,  and  on  the  outer  side  of, 
the  brachio-cephalic  artery,  and  it  is  in  contact  behind  and  on  the  right  side  with  the  right 
wall  of  the  mediastinum  and  with  the  pneumogastric  nerve,  which  are  interposed  be- 
tween it  and  the  apex  of  the  lung. 

The  relations  of  the  left  brachio-cephalic  vein  with  the  arch  of  the  aorta  account  for 
its  obliteration  in  aneurism  of  that  vessel,  and  its  relation  to  the  upper  part  of  the  ster- 
num explains  the  venous  pulse,  seen  so  distinctly  opposite  the  fourchette  of  the  sternum 
in  severe  attacks  of  dyspnoea. 

There  are  no  valves  in  the  interior  of  these  veins,  and  hence  considerable  regurgita- 
tion may  occur. 

Collateral  Branches. — The  right  brachio-cephalic  vein,  in  some  cases,  receives  only  the 
vertebral  brain  ;  but  most  commonly  the  right  inferior  thyroid  and  right  internal  mam- 
mary veins  terminate  in  it.  The  left  brachio-cephalic  vein  always  receives  the  above- 
mentioned  veins  of  its  own  side,  and  also  the  superior  phrenic,  the  thymic,  and  pericardiac 
veins,  and  often  the  superior  intercostal  vein.  As  this  last  forms  part  of  the  system  of  the 
vena  azygos,  it  will  be  described  in  another  place. 

The  Inferior  Thyroid  Veins. 

There  are  two  o  tnese,  viz.,  a  right  and  a  left  inferior  thyroid  vein :  not  unfrequently 
there  are  three,  and  even  four. 

The  course  of  the  inferior  thyroid  veins  corresponds  exactly  with  that  of  the  inferior 
thyroid  artery  of  Neubauer,  when  it  exists.  They  arise  from  the  thyroid  venous  plex- 
uses, and  sometimes  directly  from  the  superior  thyroid  vein  by  an  anastomotic  arch  ; 
they  descend  vertically  between  the  trachea  and  the  muscles  of  the  sub-hyoid  region, 
and  terminate  differently  on  the  right  and  left  sides,  the  right  inferior  thyroid  vein  ter- 
minating at  the  junction  of  the  two  brachio-cephalic  veins,  and  sometimes  even  in  the 
upper  and  anterior  part  of  the  superior  vena  cava,  while  the  vein  of  the  left  side  enters 
the  corresponding  brachio-cephalic  vein. 

In  one  case  in  which  there  were  thi-ee  inferior  thyroid  veins,  the  middle  one  ended  in 
the  superior  cava,  and  the  two  lateral  veins  in  the  corresponding  brachio-cephalic  trunks. 

These  veins,  moreover,  present  innmnerable  varieties  in  their  number,  course,  anas- 
tomoses, and  termination.  One  of  the  most  curious  and  frequent  of  these  varieties  is 
that  in  which  the  right  and  left  veins  form  an  arch,  which  receives  four  or  five  parallel 
branches  that  issue  from  the  thyroid  gland. 

The  inferior  thyroid  veins  are  joined  by  the  tracheal  and  inferior  laryngeal  veins,  so 
that  Winslow  named  them  guttural  or  tracheal.  They  form,  in  front  of  the  trachea,  a 
large  plexus,  which  it  is  impossible  to  avoid  in  performing  tracheotomy. 

The  Internal  Mammary  Veins. 

The  internal  mammary  veins  follow  the  same  course  as  the  arteries  of  that  name,  and 
receive  a  series  of  branches  corresponding  to  those  given  off  by  the  arteries,  excepting 
in  one  instance,  viz.,  the  superior  phrenic  veins,  neither  of  which,  in  general,  terminates 
in  the  corresponding  internal  mammary. 

Usually,  there  are  two  veins  of  unequal  size  for  each  internal  mammary  artery,  which 
is  placed  between  them.  The  two  almost  always  unite  into  a  single  trunk,  which  ter- 
minates on  the  right  side  at  the  junction  of  the  two  brachio-cephalic  veins,  or  in  the  up- 
per and  front  part  of  the  superior  cava,  and  on  the  left  in  the  corresponding  brachio- 
cephalic vein. 

Among  the  veins  which  open  into  the  internal  mammary,  I  should  mention  the  proper 
veins  of  the  sternum,  which  form  a  very  remarkable  venous  network  in  front  of  and  be- 
hind each  piece  of  that  bone  beneath  the  periosteum. 

The  Superior  Phrenic,  and  the  Thymic,  Pericardiac,  and  Mediastinal  Veins. 

These  are  small  veins  which  unite  into  two  groups,  one  for  the  right  side,  terminating 
at  the  junction  of  the  two  brachio-cephalic  veins,  or  at  the  upper  and  anterior  part  of  the 
superior  vena  cava ;  the  other  for  the  left,  and  teraiinating  in  the  left  brachio-cephalic 
veni.  The  pericardiac  and  mediastinal  veins  commence  upon  the  pericardium  and  the 
anterior  mediastinum. 

The  thymic  veins,  which  are  very  large  in  the  fcetus,  may  still  be  seen  in  the  adult  and 
the  aged,  for  the  th)nnus  gland  is  never  completely  absorbed. 

The  superior  phrenic  veins  are  remarkable  for  their  length  as  well  as  for  their  small 
size  ;  they  accompany  the  phrenic  nerve  and  the  superior  phrenic  arteiy :  the  left  supe- 
rior phrenic  vein  often  enters  the  corresponding  superior  intercostal  vein,  and  frequent- 
ly the  internal  mammary  vein 


THE    JUGULAR    VEINS. 


Fig.  219. 


The  Vertebral  Veins. 

The  vertebral  vein  corresponds  to  the  cervical  portion  of  the  artery  of  the  same  name, 
and,  like  it,  is  contained  in  the  canal  formed  by  the  series  of  foramina  at  the  base  of  the 
transverse  processes  of  the  cervical  vertebra  ;  it  opens  into  the  braehio-cephalic  vein  im- 
mediately behind  the  internal  jugular ;  and  it  is  said  to  open  occasionally  into  the  last- 
mentioned  vein.  Not  unfrequently,  as  Eustachius  remarks,  this  vein  divides  into  two 
branches  near  its  termination,  one  of  which  emerges  with  the  artery,  between  the  fifth 
and  sixth  vertebrae,  while  the  other,  either  alone  or  accompanied  by  a  small  arterial  twig, 
escapes  by  the  foramen  of  the  seventh  cervical  vertebra.  I  have  seen  these  two  branch- 
es emerge,  one  at  the  foramen  of  the  fifth,  the  other  at  that  of  the  sixth  cervical  vertebra. 

This  vein  commences  in  the  deep  muscles  at  the  back  of  the  neck,  communicates  by 
a  large  branch  with  the  occipital  vein,  and  sometimes  receives  a  small  branch,  which 
passes  out  at  the  posterior  condyloid  foramen  ;  it  enters  the  canal  of  the  transverse  pro- 
cesses, between  the  occipital  bone  and  the  atlas  ;  and  while  within  this  canal,  it  receives 
anterior  muscular  branches  from  the  praevertebral  region,  posterior  branches  from  the 
external  spinal  veins,  and  vertebro-spinal  branches  from  the  interior  of  the  spinal  canal. 
At  the  point  where  it  opens  into  the  braehio-cephalic  vein,  it  receives  a  large  branch, 
which  corresponds  in  its  course  to  the  ascending  cervical  artery ;  it  also  receives  the 
deep  cervical  vein,  which  has  the  same  distribution  as  the  artery  of  that  name. 

The  Jugular  Veins. 
The  jugular  veins  (from  jugulum,  the  throat)  are  three  in  number  on  each  side,  viz., 
the  internal  or  deep  jugular  {n,Jig.  219),  the  external  jugular  (A),  and  the  anterior  jugular 
(m).  The  two  latter  veins  form  part  of  the  superficial  or  sub-cutaneous  venous  system ; 
but  the  internal  jugular  is  the  satellite  vein  of  the  common  carotid  artery  and  its  branch- 
es. I  shall  describe  these  three  veins  in  succession,  but  shall  not  notice  the  veins  with 
which  they  are  directly  continuous,  nor  yet  their  branches  of  origin,  until  I  have  described 
all  three  of  them,  because  those  branches  terminate  almost  indifferently  in  either  of  them. 

The  External  Jugular  Vein. 

The  external  jugular  (h),  one  of  the  supplementary  veins  of  the  internal  jugular,  is  a 
6ub-cutaneous  vein  of  the  neck,  on  the  lateral  and 
anterior  aspect  of  which  it  is  situated.  It  is  bound- 
ed above  by  the  angle  of  the  lower  jaw  according  to 
some  authors,  by  the  neck  of  the  condyle  of  that  bone 
according  to  others  :  the  former  mode  of  limitation 
seems  to  me  to  be  preferable.  It  is  bounded  below 
by  the  clavicle,  behind  which  it  ends  in  the  sub-cla- 
vian  vein  (o),  immediately  to  the  outer  side  of  the 
internal  jugular,  and  sometimes  even  opposite  that 
vein,  but  upon  a  plane  anterior  to  it. 

The  external  jugular  is  generally  single,  but  is 
sometimes  double ;  and  this  depends  either  upon 
some  of  its  branches  of  origin  not  joining  it  until 
they  reach  the  lower  part  of  the  neck,  or  else  upon 
the  existence  of  a  small  collateral  branch,  which  ari- 
ses from  the  upper  part  of  the  external  jugular,  runs 
along  its  outer  side,  and  opens  into  it  below,  imme- 
diately before  its  termination ;  at  other  times  the 
external  jugular  bifurcates  before  it  ends  in  the  sub- 
clavian. 

The  external  jugular  varies  extremely  in  size, 
which  frequently  differs  on  the  two  sides,  and  is  not 
uniform  throughout  its  whole  length.  Thus,  it  al- 
most always  presents  an  ampulla,  or  ovoid  dilatation 
of  variable  dimensions,  near  its  termination.  In  size 
it  is  inversely  as  that  of  the  other  jugular  veins  of  the  same  and  the  opposite  side,  and 
its  differences  are  either  congenital  or  acquired ;  the  former  depending  upon  the  fact  of 
its  receiving  more  or  fewer  branches,  while  acquired  alterations  in  size  are  occasioned 
either  by  some  occupation  requiring  violent  respiratory  efforts,  or  by  the  venous  circula- 
tion being  impeded  by  disease. 

Direction.. — The  external  jugular  vein  passes  obliquely  downward  and  backward  in  the 
opposite  direction  to  the  sterno-cleido-mastoideus,  which  it  crosses  at  a  very  acute  an- 
gle, and  then  runs  parallel  to  the  posterior  border  of  that  muscle.  A  line  drawn  from 
the  angle  of  the  jaw  to  the  middle  of  the  clavicle  will  exactly  indicate  its  direction.  Op- 
posite the  clavicle,  the  external  jugular  vein  turns  forward  and  opens  into  the  sub-clavi- 
an,  either  directly,  or  after  running  horizontally  for  some  lines. 

Relations. — The  external  jugular  vein  runs  first  across  the  stemo-mastoid,  and  then 
the  supra- clavicular  region  of  the  neck.     In  the  whole  of  its  extent  it  is  covered  and 


582  ANGEIOLOGY. 

separated  from  the  skin  by  the  platysma ;  hence  the  rule  to  open  this  vein  across  the 
fibres  of  the  platysma,  when  it  is  desirable  that  the  orifice  should  be  free,  and  favourably 
disposed  for  the  flow  of  blood.  By  its  deeji  surface  it  is  in  relation  with  the  stemo- 
mastoid,  which  it  crosses  obliquely,  so  that  it  rests  above  upon  the  anterior  border  of 
that  muscle,  and  below  upon  its  external  surface,  and  parallel  with  its  outer  border. 
In  the  supra-clavicular  region  it  is  in  relation  behind  with  the  omo-hyoid  and  scalenus 
anticus  muscles  and  with  the  brachial  plexus.  It  is  always  separated  from  these  differ- 
ent parts  by  the  cervical  fascia,  which  is  perforated  by  it  as  it  curves  forward  to  entei 
the  sub-clavian  vein. 

The  external  jugular  vein  is  surrounded  by  the  superficial  nerves  of  the  cervical  plex- 
us, some  of  which  pass  in  front,  and  others  behind  it.  The  auricular  nerve  runs  behind 
its  upper  portion. 

This  vein  has  generally  two  valves,  one  in  the  middle,  the  other  near  its  termination ; 
sometimes  only  the  latter  exists.  These  valves  do  not  appear,  in  general,  to  oppose  any 
great  obstacle  to  an  injection  thrown  from  the  heart  towards  the  extremity  of  the  vein. 

Collateral  Branches. — The  external  jugular  vein  receives,  in  front,  branches  of  variable 
size  and  number,  which  communicate  with  the  anterior  jugular  vein,  and  others  which 
pass  directly  out  of  the  sterno-mastoid  muscle  ;  behind,  it  receives  the  superficial  occip- 
ital veins  (k),  and  several  superficial  branches  from  the  posterior  and  lateral  regions  of  the 
neck ;  lower  down,  it  also  receives  the  supra-scapular  and  posterior  scapular  veins  (1), 
which  exactly  correspond  to  the  arteries  of  the  same  names.  A  constant  branch  passes 
beneath  the  clavicle,  and  establishes  a  communication  between  the  external  jugular  vein 
and  the  upper  part  of  the  veins  of  the  arm. 

Branches  of  Origin. — These  are  extremely  variable  ;  most  commonly  the  external  jug- 
ular is  formed  by  the  junction  of  the  temporal  (/)  and  the  internal  maxillary  veins.  Some- 
times it  is  formed  by  a  branch  resulting  from  the  bifurcation  of  a  trunk  common  to  those 
two  veins  ;  at  other  times,  by  the  successive  juction  of  the  temporal,  internal  maxillary, 
facial,  lingual,  and  superior  laryngeal  veins. 

In  all  cases  the  external  communicates  either  directly  or  indirectly  with  the  internal 
jugular  vein  in  the  substance  of  the  parotid  gland  by  means  of  a  communicating  branch, 
which  may  be  regarded  as  a  branch  of  origin,  and  which  sometimes  is  the  only  branch  of 
origin. 

The  interior  Jttgular  Vein. 

The  anterior  jugular  is  a  sub-cutaneous  vein  {m,fig.  219),  supplementary  to  the  exter- 
nal and  even  to  the  internal  jugular,  and  collects  the  blood  from  the  parts  situated  in  the 
middle  of  the  anterior  region  of  the  neck. 

It  varies  in  size  in  different  individuals,  is  almost  always  inversely  proportioned  to  the 
external  jugular,  and  is  often  larger  than  that  vein.  We  frequently  find  both  a  right  and 
a  left  anterior  jugular  vein ;  but  then  they  are  rarely  of  equal  size.  Rather  frequently, 
however,  there  is  only  one,  scarcely  a  trace  of  the  other  existing.  Lastly,  instead  of 
these  veins,  there  are  occasionally  only  some  small  branches,  which  scarcely  deserve 
notice. 

Direction. — From  the  supra-hyoid  region,  where  it  commences,  this  vein  passes  verti- 
cally downward,  between  the  median  line  and  the  inner  border  of  the  sterno-mastoid  mus- 
cle ;  opposite  the  fourchette  of  the  sternum  it  bends  abruptly,  passes  horizontally  out- 
ward behind  the  two  lower  fasciculi  of  the  sterno-mastoid,  and  enters  the  sub-clavian 
vein  on  the  inner  side  of  the  external  jugular,  sometimes  opposite  to,  but  in  front  of  the 
internal  jugular  ;  lastly,  in  other  cases,  it  terminates  by  a  common  orifice  with  the  ex 
temal  jugular. 

During  its  course  it  runs  in  the  substance  of  that  median  layer  of  fibrous  tissue  which 
we  have  called  the  cervical  linea  alba,  and  it  receives  several  collateral  branches. 

Collateral  Branches. — The  anterior  jugular  veins  communicate  with  the  external  by 
one  or  two  branches  of  variable  size ;  they  also  communicate  freely  with  the  internal 
jugular  veins  ;  the  communicating  branches  often  form  the  origins  of  this  vein.  The  an- 
terior jugular  receives  some  laryngeal  branches,  and  sometimes  an  inferior  thyroid  vein.  At 
the  point  where  it  bends  at  the  lower  part  of  the  neck  it  receives  a  sub-cutaneous  vein, 
which  comes  from  the  upper  part  of  the  thorax,  and  passes  above  the  fourchette  of  the 
stemiun.  At  the  same  point,  also,  the  right  and  left  anterior  jugular  veins  communicate 
with  each  other  by  a  transverse  branch  {r,fig.  223),  into  which  branches  derived  from 
the  inferior  thyroid  vein,  or  even  some  branches  communicating  directly  with  the  left 
brachio-cephalic  vein,  pour  their  contents. 

Branches  of  Origin. — The  anterior  jugular  vein  often  commences  by  sub-cutaneous 
and  muscular  branches,  derived  from  the  supra-hyoid  region,  and  corresponding  in  their 
several  courses  to  the  branches  of  the  sub-mental  artery.  I  have  seen  it  arise  from  one 
end  of  a  loop,  the  other  end  of  which  was  continuous  with  the  external  jugular  vein  ;  at 
other  times  it  commences  by  a  common  trunk  with  the  facial  and  lingual  veins.  Lastly, 
I  have  seen  the  anterior  jugular  form  the  continuation  of  the  facial  vein. 


THE  INTERNAL  JUGULAR  VEIN,  ETC. 

The  Internal  Jugular  Vein. 

The  internal  jugular  vein  (n,fig.  219),  the  principal  vein  of  the  head,  collects  the  blood 
from  the  interior  of  the  cranium  and  from  the  greater  part  of  the  face  and  neck ;  it  com- 
mences at  the  posterior  lacerated  foramen,  and  terminates  in  the  brachio-cephalic  vein 
(r),  which  is  formed  by  the  junction  of  the  internal  jugular  with  the  sub-clavian  vein  (o). 
Its  direction  is  vertical,  without  any  deviation  or  bending. 

It  is  of  considerable  size,  but  varies  in  different  individuals  ;  it  is  seldom  of  equal  size 
on  both  sides,  and  is  inversely  proportioned  to  the  external  and  anterior  jugular  veins ; 
it  becomes  extremely  large  in  such  chronic  diseases  as  impede  the  entrance  of  blood 
into  the  cavities  of  the  heart.  I  have  sometimes  seen  the  internal  jugular  vein  of  the 
left  side  very  small,  its  place  being  then  supplied,  as  in  the  lower  animals,  by  a  very  large 
external  jugular. 

Moreover,  the  internal  jugular  is  not  of  uniform  size  throughout  its  whole  length.  It 
commences  at  the  posterior  lacerated  foramen  by  a  dilatation,  which  is  called  the  gulf  of 
the  internal  jugular  vein ;  it  continues  of  the  same  size  until  opposite  the  larynx,  where 
it  becomes  greatly  enlarged  in  consequence  of  receiving  several  branches  ;  it  terminates 
below  in  an  oblong  dilatation,  and  is  again  slightly  contracted  as  it  opens  into  the  brachio- 
cephalic vein.  This  oblong  dilatation  in  some  asthmatic  persons  is  very  large,  and  might 
be  called  the  sinus  of  the  internal  jugular  vein. 

That  part  of  the  internal  jugular  vein  which  extends  from  the  os  hyoides  to  the  brachio- 
cephalic vein  represents  the  common  carotid  artery ;  the  part  included  between  the  os 
hyoides  and  the  posterior  lacerated  foramen  represents  the  internal  carotid ;  and  the  se- 
ries of  branches  which  terminate  in  it  represent  the  external  carotid  and  the  ramifica- 
tions of  that  artery.  These  branches  of  the  internal  jugular,  however,  do  not  unite  into 
a  common  trunk  corresponding  to  the  trunk  of  the  external  carotid  arteiy,  so  that  the 
distribution  of  this  vein  represents  very  nearly  that  variety  in  the  distribution  of  the  ar- 
teries of  the  neck,  in  which  there  is  no  external  carotid  artery ;  the  branches  usually 
given  from  it  arising  from  the  common  carotid  artery,  which  then  terminates  in  the  in- 
ternal carotid. 

Relations. — In  that  portion  of  its  course  which  corresponds  to  the  internal  carotid  ar- 
tery, the  internal  jugular  vein  has  almost  the  same  relations  as  that  vessel :  thus,  it  is 
situated  in  the  triangular  interval  between  the  pharynx  and  the  ramus  of  the  lower  jaw ; 
the  artery,  together  with  the  pneumogastric,  hypo-glossal,  glosso-pharyngeal,  and  spinal 
accessory  nerves,  lie  to  the  irmer  side  and  in  front  of  it ;  the  styloid  and  vaginal  pro- 
cesses, and  the  styloid  muscles,  are  also  anterior  to  the  internal  jugular  vein.  That  por- 
tion of  the  vein  which  represents  the  common  carotid  artery  lies  on  the  outer  side  of 
that  vessel  and  in  contact  with  it,  excepting  below,  where  the  carotid  is  directed  some- 
what inward  to  reach  the  arch  of  the  aorta,  while  the  vein  continues  to  be  vertical,  and 
is  therefore  separated  from  the  artery.  During  its  course  it  has  the  same  relations  as 
the  artery,  only  on  account  of  being  situated  to  the  outer  side  of  that  vessel,  it  follows 
that  it  is  not  covered  by  the  platysma  myoides  to  so  great  an  extent  as  the  artery,  and, 
therefore,  that  it  is  covered  for  a  greater  length  by  the  stemo-mastoid  ;  and,  indeed,  its 
lower  end  is  inclined  to  project  beyond  the  outer  border  of  that  muscle,  so  that  in  asth- 
matic persons  the  skin  covering  the  anterior  part  of  the  supra-clavicular  triangle  be- 
comes elevated  when  the  enlarged  part  of  the  vein  is  dilated.  The  pneumogastric  nerve 
is  situated  behind,  between  the  artery  and  the  vein.  A  very  important  relation  of  the 
internal  jugular  vein  is  that  which  it  has  with  the  sub-clavian  artery,  which  is  situated 
between  it  and  the  vertebral  vein,  the  internal  jugular  being  in  front,  and  the  vertebral 
vein  behind  the  artery. 

The  internal  jugular  vein  returns  all  the  blood  from  the  interior  of  the  cranium,  re- 
ceiving it  from  the  lateral  sinus,  which  may  be  regarded  as  the  origin  of  this  vein,  and 
as  the  common  trunk  of  all  the  veins  within  the  cranium.  Its  collateral  branches,  several 
of  which  belong  sometimes  to  the  internal,  and  at  others  to  the  external  jugular,  are  the 
facial  (c),  lingual,  inferior  pharyngeal,  superior  thyroid  (all  which  open  by  a  common  trunk), 
and  middle  thyroid  veins,  sometimes  also  the  temporal  (f),  internal  maxillary,  and  deep  oc- 
cipital veins.  "We  shall  describe  in  succession  the  branches  of  origin,  and  then  the  col- 
lateral branches  of  the  internal  jugular  vein. 

The  Encephalic  Veins  and  thb  Sinuses  of  the  Dura  Mater. 

The  commencing  twigs  and  the  branches  of  the  cerebral  veins  are  like  all  other  veins, 
but  their  trunks  are  essentially  different,  for  they  consist  of  fibrous  canals,  formed,  as  it 
were,  in  the  substance  of  the  dura  mater ;  the  lining  membrane  of  these  canals  is  the 
only  part  in  which  they  correspond  in  structure  with  the  rest  of  the  venous  system,  the 
dura  mater  forming  their  outer  coat.  These  canals  are  called  the  sinuses  of  the  dura 
mater.  They  receive  the  blood  from  the  brain,  cerebellum,  and  medulla,  from  the  eye. 
and  from  the  bones  of  the  cranium. 

All  the  sinuses  of  the  dura  mater  have  a  similar  situation  ;  they  all  occupy  grooves  form- 
ed for  them  upon  the  internal  surface  of  the  bones  of  the  cranium,  and  which  we  have 
already  described.    They  are,  for  the  most  part,  situated  opposite  the  intervals  between 


ANGEIOLOGY. 

the  great  divisions  of  the  encephalon  :  thus,  the  superior  longitudinal  sinus  occupies  the 
fissure  between  the  two  hemispheres  of  the  brain  ;  the  lateral  sinuses  are  situated  op- 
posite the  great  fissure  which  separates  the  cerebrum  from,  the  cerebellum.  All  the 
sinuses  communicate  with  each  other,  and  form  an  uninterrupted  series  of  canals  ;  they 
all  open  into  the  later£il  sinuses,  which  are  to  the  other  sinuses  what  venous  trunks  are 
to  their  branches. 

There  are  twelve  sinuses  in  all,  not  including  the  inferior  longitudinal  sinus,  which  may- 
be regarded  as  a  vein.  Eight  of  the  sinuses  exist  in  pairs,  the  remaining  four  are  sin- 
gle, and  occupy  the  median  line.  The  single  sinuses  are  the  superior  longitudinal  sinus, 
the  straight  sinus,  the  coronary  sinus,  and  the  transverse  occipital  sinuses.  The  eight 
sinuses  which  exist  in  pairs  are  placed  four  on  each  side  of  the  cranium ;  they  are  the 
two  superior  and  two  inferior  petrosal,  the  two  occipital,  and  the  two  lateral  sinuses. 

As  the  lateral  sinuses  form,  as  it  were,  the  common  trunks  of  all  the  others,  I  shall 
oescribe  them  first. 

The  Lateral  Sinuses. 

The  lateral  or  transverse  sinuses  (a  a.  Jig.  221)  are  situated  in  the  lateral  grooves  {vide 
Osteology,  p.  80) ;  each  of  them  commences,  like  those  grooves,  at  the  internal  occip- 
ital protuberance,  and  passes  horizontally  outward  as  far  as  the  base  of  the  petrous  por- 
tion of  the  corresponding  temporal  bone,  at  which  point  it  dips  obliquely  downward 
and  inward  into  the  inferior  occipital  fossa,  turns  round  the  base  of  the  pars  petrosa,  and 
again  ascends  to  reach  the  posterior  lacerated  foramen  of  its  own  side  (s  s,fig.  221), 
where  it  terminates  in  the  internal  jugular  vein.  Like  the  corresponding  grooves,  the 
right  and  left  lateral  sinuses  are  of  unequal  size,  the  right  being  almost  always  the  lar- 
ger. Both  of  them  gradually  increase  in  size  from  their  posterior  extremity,  which  may 
be  regarded  as  their  origin,  to  their  anterior  extremity. 

A  section  of  the  horizontal  portion  of  each  lateral  sinus,  which  is  situated  in  the  outer 
margin  of  the  tentorium  cerebelli,  is  triangular,  while  that  of  its  vertical  or  curved  por- 
tion is  semi-cylindrical.  In  the  first  part  of  its  course  it  projects  beyond  the  correspond- 
ing groove  in  the  occipital  bone,  so  as  to  occupy  the  fissure  between  the  cerebrum  and 
cerebellum.  In  the  remamder  of  its  course  it  does  not  project  into  the  interior  of  the 
cranium,  or  pass  beyond  the  groove,  which  is  exactly  suited  to  its  dimensions. 

The  internal  surface  of  each  lateral  sinus  is  smooth,  and  it  is  not  traversed  by  bands 
like  those  found  in  the  other  sinuses.  However,  I  once  found  in  the  horizontal  portion 
of  this  sinus  some  of  the  white  bodies  called  glandulse  Pacchioni. 

One  of  the  lateral  sinuses  has  been  found  divided,  in  front,  into  two  equal  parts,  a  su- 
perior and  inferior,  by  a  perfect  horizontal  septum  ;  it  is  very  common  to  find  a  fibrous 
lamina  indicating  a  trace  of  this  subdivision. 

The  anterior  extremity  of  each  lateral  sinus  is  continuous  with  the  gulf  of  the  corre- 
sponding internal  jugular  vein,  and  the  inferior  petrosal  sinus  of  its  own  side  opens  into 
it  at  the  same  point.  During  its  course  it  receives  some  inferior  cerebral  veiris,  some  cere- 
bellar veins,  and  the  superior  petrosal  sinus  (/),  which  enters  it  at  the  point  where  it  chan- 
ges its  direction  from  horizontal  to  oblique,  i.  e.,  opposite  the  base  of  the  petrous  portion 
of  the  temporal  bone. 

The  lateral  and  inferior  cerebral  veins  commence  partly  on  the  lateral  and  inferior  parts 
of  the  convex  surface  of  the.  cerebrum,  and  partly  on  the  base  of  the  brain  ;  they  unite 
so  as  to  form  a  group  of  three,  four,  or  five  veins,  which  open  into  the  horizontal  por- 
tion of  the  lateral  sinus.  They  enter  from  before  backward,  that  is  to  say,  in  an  oppo- 
site direction  to  the  course  of  the  blood  in  the  sinus.  One  of  these  veins  is  sometimes 
observed  to  run  along  the  tentorium  cerebelli,  with  which  it  is  maintained  in  contact  by 
the  parietal  layer  of  the  arachnoid  for  about  an  inch  before  it  opens  into  the  lateral  sinus 

The  lateral  and  inferior  cerebellar  veins  are  very  large  ;  they  commence  upon  the  lower 
surface  of  the  cerebellum,  and  terminate  in  two  or  three  trunks,  which  are  found  upon 
the  circumference  of  the  cerebellum,  and  open  into  the  horizontal  portion  of  the  lateral 
sinus  by  perforating  its  lower  wall. 

A  large  mastoid  vein,  which  may  be  regarded  as  one  of  the  principal  origins  of  the  oc- 
cipital, also  opens  into  the  lateral  sinus,  and  thus  establishes  a  free  and  direct  commu- 
nication between  the  venous  system  within  and  that  outside  the  cranium. 

The  Superior  Longitudinal  Sinus. 

The  superior  longitudinal  sinus  {b  b,fig.  220)  is  a  single  and  median  sinus,  which  occu- 
pies the  longitudinal  groove,  and  accordingly  extends  from  the  crista  galli  to  the  inter- 
nal occipital  protuberance ;  it  is  formed  within  the  substance  of  the  convex  border  of  the 
falx  cerebri,  and  is  three-sided;  a  section  of  it  represents  an  isosceles  triangle  {I,  Jig. 
221),  with  its  base  turned  upward  and  its  apex  downward.  It  is  small  at  its  anterior 
extremity,  but  gradually  increases  in  size  as  it  approaches  the  confluence  of  the  sinuses 
(«,  Jig.  221),  in  which  it  terminates.  It  not  unfrequently  bifurcates  near  its  posterior  ex- 
tremity ;  sometimes  it  is  directly  continuous  with  the  right  lateral  sinus. 

The  internal  surface  of  this  sinus  is  remarkable  for  the  transverse  bands  found  in  it. 


THE   SUPERIOR  LONGITUDINAL    SINUS,  ETC.  6S5 

especially  along  its  inferior  angle.    These  bands  Fi^.  S20. 

consist  of  fibrous  tissue  covered  by  the  lining  mem- 
brane of  the  sinus,  and  they  conceal  the  orifices 
of  the  veins  which  open  into  it ;  in  some  points 
they  are  so  numerous  as  to  form  an  areolar  tissue. 
Lastly,  we  ahnost  always  find  on  the  internal  sur- 
face of  the  sinus  some  small  white  projecting  bod- 
ies, the  glandulce  Pacchioni. 

The  following  veins  open  into  the  superior  lon- 
gitudinal sinus :  some  from  the  internal  or  flat  sur- 
face of  each  cerebral  hemisphere,  called  the  inter- 
nal cerebral  veins ;  others  from  the  upper  half  of  the 
convex  surface  of  the  brain,  or  the  external  cere- 
bral ;  and,  lastly,  several  veins  from  the  dura  mater 
and  the  bones  of  the  cranium. 

The  internal  cerebral  veins,  three  or  four  in  number  on  each  side,  return  the  blood  from 
all  the  convolutions  of  the  flat  surface  of  the  corresponding  hemisphere  of  the  brain,  and 
enter  the  superior  cerebral  veins  at  the  point  where  these  are  applied  to  the  surface  of 
the  falx. 

The  superior  cerebral  veins  vary  in  number,  but  are  generally  seven  or  eight  on  each  side. 
The  anterior  of  these  veins  are  very  small ;  the  posterior  are  much  larger.  There  is  al- 
most always  one  of  greater  size  than  the  rest,  which  may  be  named  the  great  superior 
cerebral  vein :  it  appears  to  commence  in  and  run  along  the  fissure  of  Sylvius,  is  then 
prolonged  obliquely  backward,  and  turning  forward  upon  the  convex  surface  of  the  brain, 
so  as  to  describe  a  curve  having  its  concavity  directed  forward,  it  becomes  applied  to 
the  falx  cerebri,  and  opens  into  the  longitudinal  sinus,  after  having  run  for  about  one  inch 
in  the  substance  of  its  walls.  During  its  course  this  vein  receives  a  great  number  of 
branches,  some  anterior  and  others  posterior,  which,  although  corresponding  to  the  arter- 
ies in  their  origin  and  in  a  part  of  their  course,  are  completely  separated  from  those  ves- 
sels at  their  termination.  The  common  trunks  pass  inward  towards  the  great  median 
fissure  of  the  brain  ;  near  the  sinus  they  become  attached  to  the  dura  mater,  being  held 
down  by  the  arachnoid  membrane,  which  is  reflected  from  the  brain  upon  the  dura  ma- 
ter; they  then  change  their  direction,  turn  forward  in  the  substance  of  the  falx  cerebri, 
beneath  a  very  thin  layer  of  the  dura  mater,  and  after  a  course  of  from  six  to  ten  lines  in 
length,  terminate  in  the  longitudinal  sinus  by  one  or  more  openings.  The  manner  in 
which  the  cerebral  veins  open  into  the  sinus  varies  :  for  some  there  are  lateral  openings, 
as  if  made  by  a  punch  ;  others  open  by  means  of  an  areola  fibrous  tissue,  which,  as  I  have 
already  stated,  is  found  in  certain  parts  of  the  walls  of  the  sinuses.  All  the  venous  ori- 
fices are  concealed  by  fibrous  areolae,  none  of  the  veins  opening  directly  into  the  sinus. 
Most  of  them  run  for  a  certain  distance  from  behind  forward,  i.  e.,  in  an  opposite  direction 
to  the  course  of  the  blood,  before  they  open  into  the  sinus ;  the  most  anterior  veins, 
which  run  from  before  backward,  are  the  only  exceptions  to  this  rule.  Moreover,  the  fold 
or  bands  which  are  formed  in  this  and  other  sinuses  do  not  perform  the  functions  of 
valves,  for  they  permit  fluids  to  pass  from  the  sinus  into  the  veins.  The  inferences  drawn 
by  physiologists  from  the  direction  in  which  the  cerebral  veins  open  into  the  sinuses  ap- 
pear to  me  to  be  erroneous,  for  that  direction  facilitates  instead  of  opposing  the  reflux 
of  the  blood.  I  have  satisfied  myself  that  the  cerebral  veins  have  no  valves  in  any  part 
of  their  extent. 

The  superior  longitudinal  sinus  also  receives  proper  veins  from  the  dura  mater,  some 
venous  or  diploic  veins,  and  several  veins  which  conmience  in  the  pericranium,  and  es- 
tablish a  communication  between  the  external  and  internal  veins  of  the  cranium.  Among 
the  communicating  veins  are  those  which  traverse  the  parietal  foramina,  and  are  called 
the  veins  of  Santorini.  A  very  great  number  of  veins  penetrate  through  the  longitudinal 
suture,  to  open  into  the  corresponding  sinus  in  young  subjects ;  the  communication  of  the 
diploic  veins  with  those  of  the  dura  mater,  and  with  the  sinuses  and  cerebral  veins,  may 
be  shown  by  perforating  with  a  pin,  in  a  young  subject,  the  very  thin  and  brittle  external 
bony  table  which  covers  one  of  the  numerous  veins  of  the  diploe,  and  then  inserting  into 
the  orifice  the  fine  point  of  a  mercurial  injecting  apparatus  :  the  mercury  will  fill  the  diplo- 
ic veins,  and  will  pass  into  the  sinuses,  the  veins  of  the  dura  mater,  and  the  cerebral  veins 

The  Straight  Sinus. 

The  straight  sinus  (,c,Jig.  220)  occupies  the  base  of  the  falx  cerebri,  corresponding  with 
the  line  of  junction  of  the  falx  with  the  tentorium  cerebelli. 

The  straight  sinus  is  therefore  single,  and  situated  in  the  median  line ;  it  is  directed 
somewhat  obliquely  backward  and  downward,  and  it  opens  into  the  confluence  of  the  si- 
nuses or  torcular  Herophili  (n),  by  one  or  sometimes  two  orifices,  according  to  the  pres- 
ence or  absence  of  a  vertical  band  across  its  termination.  It  is  three-sided,  and  a  sec- 
tion of  it  represents  an  isosceles  triangle  {c,fig.  221),  having  its  base  turned  downward. 

This  sinus  increases  in  size  as  it  proceeds  backward. 

4  £ 


<S86  ANGEIOLOGY. 

The  straight  sinus  receives  by  its  anterior  extremity  the  inferior  loTigitudinal  vein  or 
sinus,  the  two  great  vc7itricular  veins  or  vena  Galeni,  the  inferior  median  cerebral  veins,  and 
the  superior  median  cerebellar  vein. 

The  inferior  longitudinal  vein  (rf),  which  is  generally  but  incorrectly  described  as  the 
inferior  longitudinal  sinus,  may  be  regarded  as  an  ordinary  vein  enclosed  within  the  pos- 
terior half  of  the  free  margin  of  the  falx  cerebri.  This  vein  increases  in  size  from  be- 
fore backward,  and  enters  directly  into  the  straight  sinus.  It  sometimes  bifurcates  be- 
fore its  termination,  and  then  the  lower  branch  of  the  bifurcation  opens  into  the  anterior 
extremity  of  the  straight  sinus,  and  the  upper  describes  a  decided  curve,  and  enters  at 
the  middle  of  that  sinus. 

The  inferior  longitudinal  vein  receives  the  proper  veins  of  the  falx  cerebri.  It  seldom 
receives  any  vein  belonging  to  the  brain  itself. 

The  ventricular  veins,  or  vena  Galeni  (c),  are  two  in  number,  one  proceeding  from  the 
left,  and  one  from  the  right  lateral  ventricle.  Each  of  them  is  formed  by  the  union  of  two 
branches,  viz.,  the  choroid  vein,  and  the  vein  of  the  corpus  striatum. 

The  choroid  vein  runs  along  the  whole  length  of  the  outer  border  of  the  choroid  plexus, 
m  a  direction  from  behind  forward.  During  this  course  it  receives  the  vein  from  the 
hippocampus  major,  one  from  the  fornix,  and  one  from  the  corpus  callosum,  and  having 
reached  the  anterior  extremity  of  the  choroid  plexus,  it  turns  back  again  within  the  sub- 
stance of  the  plexus,  and  unites  with  the  vein  of  the  corpus  striatum. 

The  vein  of  the  corpus  striatum  is  much  smaller  than  the  preceding ;  it  commences  be- 
hind in  the  furrow  between  the  corpus  striatum  and  the  thalamus  opticus,  traverses  the 
whole  length  of  that  furrow,  covered  by  the  taenia  semicircularis,  receives,  during  its 
course,  a  great  nmnber  of  small  veins  from  the  corpus  striatum  and  thalamus  opticus, 
and  having  arrived  behind  the  anterior  pillow  of  the  fornix,  unites  with  the  choroid  vein 
to  form  one  of  the  venae  Galeni. 

The  two  vena  Galeni  proceed  parallel  with  each  other,  and  horizontally  backward  be- 
neath the  velum  interpositum,  pass  out  from  the  brain  beneath  the  corpus  callosum,  and 
immediately  enter  the  straight  sinus  below  the  opening  of  the  inferior  longitudinal  vein 
without  crossing  each  other,  as  is  stated  by  some  anatomists. 

Not  unfrequently  we  find  an  anterior  and  superior  cerebellar  vein  opening  into  the  ve- 
nae Galeni,  as  the  latter  enter  the  straight  sinus. 

The  inferior  median  cerebral  veins  are  very  large.  One  is  anterior,  and  commences 
upon  the  fore  part  of  the  lower  surface  of  the  cerebrum,  and  turns  round  its  correspond- 
ing crus ;  while  the  other,  which  is  posterior,  arises  upon  the  posterior  convolutions ; 
they  both  enter  the  anterior  extremity  of  the  straight  sinus,  behind  the  venas  Galeni. 

The  superior  mediaii  cerebellar  vein  passes  upward  between  the  valve  of  Vieussens  and 
the  superior  vermiform  process,  and  opens  into  the  anterior  extremity  of  the  straight 
sinus. 

The  Superior  Petrosal  Sinuses. 

The  superior  petrosal  sinuses  {fffg-  221)  are  situated  along  the  upper  border  of  the 
Pig,  221.  petrous  portion  of  the  temporal  bones,  and  are  partly  lodged 

in  the  small  corresponding  grooves  ;  they  are  continuous  as 
regards  their  direction  with  the  horizontal  portion  of  each 
lateral  sinus,  and  occupy  the  anterior  half  of  the  lateral  or 
adherent  borders  of  the  tentorium,  the  lateral  sinuses  occu- 
pying the  posterior  half  They  are  very  small,  and,  hke  the 
part  of  the  lateral  sinus  with  which  they  are  continuous, 
they  are  three-sided.  The  anterior  extremity  of  each  su- 
perior petrosal  sinus  communicates  with  the  corresponding 
cavernous  sinus  {h  h) ;  and  its  posterior  extremity  opens 
into  the  corresponding  lateral  sinus  at  the  point  where  the 
latter  leaves  the  tentorium  cerebeUi  to  turn  round  the  base 
of  the  petrous  portion  of  the  temporal  bone. 

The  superior  petrosal  sinuses,  therefore,  establish  a  di- 
rect communication  between  the  cavernous  and  the  lateral 
sinuses  ;  they  sometimes  receive  an  inferior  lateral  cerebral 
vein,  but  always  an  anterior  lateral  cerebellar  vein,  which 
passes  upward  under  the  free  margin  of  the  tentorium  cerebeUi,  behind  the  fifth  pair  of 
nerves.  The  veins  which  come  from  the  sides  of  the  pons  Varolii  also  enter  the  an- 
terior extremity  of  this  sinus. 

The  Inferior  Petrosal  Sinuses. 

The  inferior  petrosal  sinuses  (g  g)  are  situated,  one  on  each  side,  upon  the  petro-occip- 
ital  sutures,  and  lie  in  corresponding  grooves  ;  each  of  them  extends  from  the  anterior 
to  the  posterior  lacerated  foramen  of-  its  own  side.  They  are  larger  than  the  superior 
petrosal  sinuses,  and  are  semi-cylindrical,  like  the  anterior  part  of  the  lateral  sinuses, 
with  which  they  are  continuous.     The  anterior  extremity  of  each  opens  into  the  anterior 


THE    CAVERNOUS   SINUSES,   ETC. 

occipital  sinus  (r)  and  into  the  cavernous  sinus  of  its  own  side ;  while  its  posterior  ex- 
tremity opens  into  the  anterior  end  of  the  corresponding  lateral  sinus,  opposite  the  com- 
mencement of  the  internal  jugular  vein  (s).  These  sinuses  establish  a  free  anastomosis 
between  the  anterior  and  posterior  sinuses  found  at  the  base  of  the  cranium. 

Excepting  one  vein  which  comes  from  the  base  of  the  cranium  through  the  foramen 
lacerum  anticus,  the  inferior  petrosal  sinus  receives  no  vein  of  importance. 

The  Cavernous  Sinuses. 

The  cavernous  sinuses  (h  h),  so  named  from  their  reticulated,  and,  as  it  were,  spongy 
structure,  occupy  the  sides  of  the  sella  turcica  and  the  grooves  on  the  body  of  the  sphe- 
noid bone.  Each  cavernous  sinus  is  bounded  in  front  by  the  inner  part  of  the  sphenoidal 
fissure,  and  behind  by  the  apex  of  the  petrous  portion  of  the  temporal  bone  :  its  cavity 
(shown  on  the  right  side  in  the  figure)  is  larger  than  it  at  first  sight  appears  to  be,  but  is 
encroached  upon  by  the  internal  carotid  artery,  which  curves  twice  upon  itself  during  its 
passage  through  the  sinus,  and  also  by  the  abducens  oculi,  or  sixth  cranial  nerve.  The 
motor  oculi  or  third  nerve,  the  trochlearis  or  fourth,  and  the  ophthalmic  branch  of  the 
fifth  cranial  nerve,  are  situated  in  the  substance  of  tlie  outer  wall  of  the  sinus.  It  is 
traversed  by  reddish  reticulated  filaments,  the  nature  of  which  is  unknown.  The  older 
anatomists  said  that  the  internal  carotid  artery  and  the  sixth  nerve  were  bathed  in  the 
blood  of  the  sinus ;  but  it  is  now  generally  believed,  in  accordance  with  the  opinion  of 
Bichat,  that  they  are  protected  by  the  lining  membrane  of  the  veins ;  it  is  difficult  to 
prove  the  accuracy  of  this  opinion,  although  analogy  is  in  its  favour.  Bichat  also  thought 
that  the  reticulated  filaments  mentioned  above  were  folds  of  the  lining  membrane  of  the 
vein.  The  anterior  extremity  of  each  cavernous  sinus  has  been  named  the  ophthalmic 
sinus,  doubtless  on  account  of  its  being  prolonged  outward.  Its  posterior  extremity  opens 
into  the  corresponding  superior  and  inferior  petrosal  sinuses,  and  into  the  transverse  oc- 
cipital sinus.  On  the  inner  side  it  receives  t)ie  coronary  sinus,  which  establishes  a  di- 
rect communication  between  the  right  and  left  cavernous  sinuses.  Lastly,  each  cavern- 
ous sinus  receives  below  several  branches,  which  connect  the  veins  within  with  those 
outside  the  base  of  the  cranium,  more  particularly  with  the  pterygoid  venous  plexuses. 

The  cavernous  sinuses  receive  in  front  the  inferior  and  anterior  cerebral  veins,  which 
commence  upon  the  lower  surface  of  the  anterior  lobe  of  the  cerebrum.  The  largest  of 
these  veins  on  each  side  reaches  the  sphenoidal  fissure,  turns  backward  over  the  lateral 
and  middle  fossa  of  the  base  of  the  cranium,  and  enters  the  middle  meningeal  vein. 
Several  anatomists  state  that  they  have  seen  the  middle  meningeal  veins  open  into  the 
cavernous  sinuses. 

Lastly,  the  anterior  extremity  of  each  of  these  sinuses  receives  the  ophthalmic  vein. 

The  ophthalmic  vein  is  a  very  large  vessel,  which  commences  on  the  inner  side  of  the 
orbit  as  a  continuation  of  the  frontal  vein,  and  terminates  by  opening  into  the  anterior 
extremity  of  the  corresponding  cavernous  sinus ;  and  it  thus  establishes  a  very  free  com- 
munication between  the  veins  of  the  interior  and  exterior  of  the  cranium.  It  pursues 
the  same  course  as  the  ophthalmic  artery,  but  without  any  windings,  and  receives  venous 
branches  corresponding  to  the  ramifications  of  that  artery.  Among  them,  I  shall  men- 
tion particularly  the  ciliary  veins,  which  commence  in  the  choroid  membrane  of  the  eye, 
where  they  are  called  vasa  vorticosa,  on  account  of  being  arranged  in  whirls. 

The  Coronary  Sinus. 

The  coronary  sinus,  or  circular  sinus  of  Ridley  (i),  runs  round  the  margin  of  the  pituitary 
fossa,  and  completely  surrounds  the  pituitary  body.  Its  posterior  is  much  larger  than 
its  anterior  half.  In  old  subjects  it  is  not  rare  to  find  the  quadrilateral  plate  of  the  sphe- 
noid bone  behind  the  pituitary  fossa  worn  away,  as  if  corroded  by  the  blood  of  the  sinus, 
so  that  it  may  easily  be  broken.  At  this  period  of  life,  the  coronary  sinus  is  larger  than 
in  young  subjects,  and  extends  under  the  pituitary  body  itself 

The  coronary  sinus  only  receives  osseous  veins  from  the  sphenoid,  some  veins  from 
the  dura  mater,  and  those  from  the  pituitary  body.  It  opens  freely  on  each  side  into  the 
cavernous  sinuses,  which  thus  communicate  with  each  other. 

The  Anterior  Occipital,  or  the  Basilar  Sinus. 

The  anterior  or  transverse  occipital  sinus  (r)  is  median  and  single ;  it  extends  trans- 
versely across  the  basilar  groove  from  the  foramen  lacerum  posticus  of  one  side  to  that 
of  the  other  ;  it  is  of  an  irregular  form,  much  larger  in  the  aged  than  in  adult  and  young 
snbjects,  and  connects  the  superior  and  inferior  petrosal  sinuses  and  the  ca\  ernous  sinus 
of  one  side  with  the  corresponding  sinuses  of  the  opposite  side.  In  old  subjects,  the 
basUar  surface  not  unfrequently  appears  as  if  corroded  opposite  this  sinus,  the  cavity  ol" 
which  often  presents  a  cellular  or  spongy  structure. 

The  Posterior  Occipital  Sinuses. 
These  {k  k)  are  the  smallest  of  all  the  sinuses  of  the  dura  mater  ;  they  commence  one 
at  each  foramen  lacerum  posticus,  pass  from  thence  upon  each  side  of  the  foramen 


688  ANGEIOLOGY. 

magnum,  converge  towards  the  falx  cerebelli,  enter  its  substance,  and  open  separately 
into  the  confluence  of  the  sinuses  :  they  receive  some  small  veins  from  the  bones  of  the 
cranium  and  from  the  dura  mater :  the  posterior  occipital  sinuses  may  be  said  to  repre- 
sent the  chord  of  the  arc  formed  by  the  lateral  sinuses.* 

The  Confluences  of  the  Sinuses. 

From  what  has  been  stated  above,  it  appears  that  there  are  three  central  points  in 
which  all  the  sinuses  meet :  one  situated  behind  and  in  the  middle  line,  and  one  on  each 
side  of  the  middle  line  in  front.  The  term  confluence  of  the  sinuses  might  be  applied  to 
all  three  points,  but  it  has  hitherto  been  confined  to  the  posterior  and  median  central 
point,  or  occipital  confluence.  All  the  sinuses  open  directly  into  one  of  these  three 
points,  the  inferior  longitudinal,  if  it  be  considered  a  sinus,  forming  the  only  exception. 

The  Posterior  or  Occipital  Confluence,  or  Torcular  Herophili. — If  that  portion  of  the  dura 
mater  which  corresponds  to  the  occipital  protuberance  be  opened  from  behind,  six  ori- 
fices will  be  exposed  to  view,  viz.,  a  superior,  which  belongs  to  the  superior  longitudinal 
sinus  ;  an  anterior,  sometimes  divided  into  two  by  a  vertical  band,  which  belongs  to  the 
straight  sinus ;  two  lateral  orifices,  which  belong  to  the  two  lateral  sinuses  ;  and  two  in- 
ferior, which  belong  to  the  posterior  occipital  sinuses.  The  point  at  which  these  sinuses 
meet  is  named  the  torcular  Herophili  (n  n,figs.  220,  221),  because  it  is  supposed  that  the 
columns  of  blood  flowing  from  the  different  sinuses  must,  in  some  degree,  press  against 
each  other. 

The  Anterior  or  Petro- sphenoidal  Confluence. — Between  the  apex  of  the  petrous  portion 
of  the  temporal  bone  and  the  sphenoid  bone,  there  is  on  each  side  another  confluence, 
at  which  a  great  number  of  sinuses  meet,  viz.,  in  front,  the  cavernous  sinus  and  the  cor- 
onary sinus ;  on  the  inside,  the  transverse  occipital  sinus ;  and  behind,  the  superior  and 
inferior  petrosal  sinuses. 

The  Branches  op  Origin  of  the  Jugular  Veins. 

The  Facial  Vein. 

The  facial,  or  external  maxillary  vein  (e,  fig.  219),  represents  the  artery  of  the  same 
name  ;  also  the  terminal  divisions  of  the  ophthalmic  artery ;  and,  lastly,  some  of  the 
branches  of  the  internal  maxillary  artery. 

It  commences  in  the  frontal  region,  where  it  is  called  the  frontal  vein ;  at  the  inner 
angle  of  the  eye  it  is  named  the  angular  vein ;  and  afterward  the  facial  vein  until  its  ter- 
mination. 

The  frontal  vein  (la  vein  preparate,  a,  fig.  219)  is  a  sub-cutaneous  vein,  which  was  se- 
lected by  the  ancients  for  phlebotomy :  it  is  sometimes  single,  and  is  then  placed  in  the 
median  line ;  but  there  are  generally  two  frontal  veins  united  by  a  transverse  anasto- 
mosis. Among  the  numerous  varieties  which  this  vein  presents,  I  shall  point  out  one 
in  which  the  two  frontal  veins  are  united  into  a  single  trunk,  which  bifurcates  above  the 
root  of  the  nose.  These  veins  do  not  exactly  follow  the  course  of  the  frontal  arteries  ; 
they  descend  from  the  vertex,  where,  by  their  numerous  anastomoses,  either  with  each 
other  or  with  the  temporal  veins,  they  form  a  venous  plexus  large  enough  to  cover  the 
whole  frontal  region.  They  open  into  a  transverse  venous  arch,  having  its  concavity 
directed  downward  ;  it  is  sometimes  tortuous  :  it  is  situated  at  the  root  of  the  nose,  and 
is  named  the  nasal  arch  (t).  This  arch  is  also  joined  by  the  supra-orbital  vein,  a  deep- 
seated  vessel  (indicated  by  the  dotted  lines  c),  which  runs  transversely  along  the  upper 
part  of  the  orbit,  receives  the  superior  internal  palpebral  vein,  and  opens  into  the  ex- 
tremity of  the  arch,  on  the  outer  side  of  the  frontal  vein  :  the  ophthalmic  vein  also  termi- 
nates in  the  nasal  arch  of  the  vein,  between  which  and  the  cavernous  sinus  it  establishes 
a  free  communication.  Thus  the  upper  parts  of  the  face,  more  particularly  the  eye  and 
its  appendages,  are  intimately  connected  with  the  brain  through  the  medium  of  the  veins 
as  well  as  of  the  arteries.  Moreover,  the  dorsal  veins  of  the  nose,  which  run  on  each  side 
of  the  ridge  of  that  organ,  open  into  the  concavity  of  the  nasal  arch. 

The  angular  veins  are  given  off  from  the  right  and  left  extremities  of  the  nasal  arch, 
and  may  be  regarded  as  the  continuations  of  the  frontal  veins  ;  like  the  corresponding 
arteries,  each  of  them  (d)  is  situated  in  the  furrow  between  the  nose  and  the  cheek. 
The  inferior  palpebral  vein  and  the  vein  of  the  lachrymal  sac  and  nasal  duct  enter  the  outer 
side  of  each  angular  vein,  which  is  joined  on  its  inner  side  by  the  veins  of  the  corre- 
sponding ala  of  the  nose. 

The  veins  qf  the  ala  nasi  form  a  very  dense  network  between  the  cartilage  and  the  skin, 
and  also  between  the  cartilage  and  the  mucous  membrane  ;  from  these  networks  two 
branches  are  given  off:  a  superior,  which  runs  along  the  convex  border  ;  and  an  infe- 
rior, which  runs  along  the  lower  border  of  the  inferior  lateral  cartilage,  or  the  cartilage 
of  the  ala.  These  two  branches  unite  into  a  very  large  common  trunk,  which  passes 
upward,  often  very  obliquely,  into  the  angular  vein. 

The  facial  vein  (e)  commences  in  the  angular  vein,  at  the  point  where  the  latter  is 

*  [They  sometimes  join  the  lateral  sinuses  in  front,  as  shown  in  the  figure.] 


THE    TEMPORO-MAXILLARY    VEIN.  58^ 

joiaed  by  the  veins  of  the  nose  ;  it  proceeds  very  obhquely  dovi^nward  and  outward, 
passes  under  the  great  zygomatic  muscle,  reaches  and  then  runs  along  the  anterior  bor- 
der of  the  masseter,  crosses  at  right  angles  over  the  base  of  the  jaw,  is  received  into  a 
groove  in  the  sub-maxillary  gland,  and  terminates  in  several  different  modes. 

Most  commonly,  it  unites  with  the  lingual  to  form  a  common  trunk,  which  enters  the 
internal  jugular ;  it  is  into  this  common  trunk  of  the  facial  and  lingual  veins  that  the  su- 
perior thyroid  and  the  pharyngeal  vein,  and  the  common  trunk  of  the  temporal  and  inter- 
nal maxillary  veins,  sometimes  open.  In  other  cases  the  facial  vein  passes  obliquely 
across  the  outer  surface  of  the  sterno-mastoideus,  and  enters  at  some  point  of  the  exter- 
nal jugular  vein.  I  have  seen  it  directly  continuous  with  the  anterior  jugular,  also  with 
the  external  jugular  of  the  same  or  of  the  opposite  side,  or  it  may  enter  the  convexity 
of  an  arch  of  conununication  between  the  external  and  anterior  jugular  veins. 

Collateral  Branches. — During  its  course  the  facial  vein  in  joined  on  its  outer  side  by  the 
alveolar  venous  trunk,  which  is  very  large,  and  may  be  regarded  as  the  deep  branch  of 
origin  of  the  facial  vein,  which,  in  fact,  becomes  much  larger,  sometimes  even  twice  as 
large,  after  its  reception.  This  alveolar  trunk  commences  in  a  very  remarkable  venous 
plexus,  named  the  alveolar  plexus,  in  which  the  alveolar  veins  ■properly  so  called,  together 
with  the  infra-orbital,  superior  palatine,  vidian,  and  spheno-palatine  veins  terminate,  and 
which  communicates  with  the  pterygoid  plexus.  All  these  veins  accompany  the  branches 
of  the  internal  maxillary  artery  having  the  same  names.  From  the  alveolar  plexus  the 
alveolar  trunk  runs  forward  and  downward  below  the  malar  bone,  and  unites  obliquely 
with  the  facial  vein.  The  facial  is  also  joined  on  its  inner  side  by  the  superior  and  infe- 
rior coronary  veins  of  the  lip,  which  are  distributed  like  the  arteries,  but  are  not  tortu- 
ous ;  by  the  buccal  vein  or  veins  ;  and  by  the  anterior  masseteric  veins. 

Below  the  base  of  the  jaw,  the  facial  vein  is  joined  by  the  sub-mental  vein  ;  by  the  in- 
ferior palatine,  which  is  remarkable  for  the  plexus  around  the  tonsils,  which  is  formed  al 
most  entirely  by  it ;  also  by  the  vein  or  veins  from  the  sub-maxillary  gland,  and  some- 
times by  the  ranine  vein. 

During  its  course  the  facial  vein  is,  in  general,  more  superficial  than  the  facial  artery, 
and  does  not  accompany  it  on  the  face,  but  is  situated  more  to  the  outside,  and  is  not 
tortuous. 

The  Temporo-maxillary  Vein. 

The  temporo-maxillary  vein,  or  venous  trunk,  represents  the  temporal  artery,  a  part  of 
the  internal  maxillary,  and  the  upper  part  of  the  external  carotid  :  many  authors  follow 
Walther  in  naming  it  the  posterior  facial  vein,  in  contradistinction  to  the  facial  vein  prop- 
erly so  called,  which  they  name  the  anterior  facial.  The  temporo-maxillary  is  formed 
by  the  junction  of  the  temporal  and  internal  maxillary  veins  :  it  most  frequently  termi- 
nates in  the  external  jugular  vein. 

The  Temporal  Vein. — This  vein  commences  above  by  superficial,  middle,  and  deep 
branches. 

The  superficial  temporal  veins  (f,fig.  219)  commence  upon  the  crown  of  the  head  by 
anterior  or  frontal  branches,  which  communicate  freely  with  the  origin  of  the  frontal  vein, 
by  middle  or  parietal  branches,  which  communicate  with  the  corresponding  branches  of 
the  opposite  side,  and  by  posterior  or  occipital  branches,  which  communicate  with  the 
branches  of  the  occipital  vein.  These  form  a  very  open  network  over  the  greater  part 
of  the  cranium.  From  this  network  anterior  and  posterior  branches  arise,  and  unite 
with  each  other  above  or  opposite  to  the  zygomatic  arch.  During  this  course  the  veins 
do  not  exactly  follow  the  direction  of  the  corresponding  arteries.  It  might  be  said  that 
the  veins  of  the  scalp  partake  of  the  characters  both  of  the  venae  comites  and  the  sub- 
cutaneous veins.  These  venous  networks  are,  moreover,  situated  in  the  substance  of 
the  hairy  scalp,  and,  like  the  arteries,  are  placed  between  the  skin  and  the  occipito- 
frontalis  muscle. 

The  middle  temporal  vein  is  a  very  large  vessel,  often  much  larger  than  the  common 
trunk  of  the  superficial  veins.  It  is  situated  (as  indicated  by  the  dotted  lines,  g,fig.  219) 
beneath  the  temporal  fascia,  between  it  and  the  temporal  muscle.  It  is  sometimes 
formed  principally  by  the  junction  of  the  palpebral  with  the  external  orbital  veins,  which, 
corresponding  in  their  distribution  to  the  arteries  of  the  same  name,  unite  into  a  common 
trunk  that  runs  backward  at  first  between  the  two  layers  of  the  temporal  fascia,  then  be- 
tween the  muscle  and  the  fascia,  is  directed  backward  and  downward,  again  perforates 
the  fascia  from  within  outward  above  the  antero-posterior  root  of  the  zygomatic  process, 
and  unites  with  the  superficial  temporal  vein  in  front  of  the  external  auditory  meatus. 

The  trunk  resulting  from  the  junction  of  the  superficial  temporal  and  middle  temporal 
veins  passes  vertically  downward,  between  the  external  auditory  meatus  and  the  tem- 
poro-maxillary articulation,  dips  into  the  substance  of  the  parotid  gland,  and,  having  ar- 
rived behind  the  neck  of  the  condyle,  receives  the  internal  maxillary  vein,  wliich  consti- 
tutes the  deep  origin  of  the  temporo-maxillary  trunk. 

The  Internal  Maxillary  Vein. — This  vein,  the  deep  origin  of  the  temporo-maxillary  trunk, 
is  called  by  Meckel  the  internal  and  posterior  maxillary,  in  opposition  to  the  alveolar  branch 


600  «*>  ANGEIOLOGY. 

of  the  facial  vem/wRicIi^lie  calls  the  internal  and  anterior  maxillary:  it  corresponds  to  all 
the  branches  given  off  from  the  internal  maxillary  artery  behind  the  neck  of  the  condyle, 
in  the  zygomato-maxillary  fossa ;  while  the  alveolar  vein,  the  deep  branch  of  the  facial, 
corresponds  to  all  the  branches  given  off  by  the  internal  maxillary  artery  upon  the  tuber- 
osity of  the  superior  maxilla  and  in  the  pterygo-maxillary  fossa. 

Thus  it  is  joined  by  the  middle  meningeal  veins.  The  venae  comites  of  the  middle  me- 
ningeal artery,  the  existence  of  which  has  been  erroneously  denied,  are  two  in  number, 
and  are  situated,  one  in  front,  the  other  behind  the  artery.  These  veins  often  receive 
some  inferior  and  anterior  cerebral  veins,  which  enter  them  near  the  foramen  spinosum 
of  the  sphenoid ;  they  always  receive  veins  from  the  bones  of  the  cranium  and  from  the 
dura  mater,  and  communicate  with  the  superior  longitudinal  sinus  ;  they  are  sometimes 
so  large,  especially  the  anterior  branch,  that  they  have  deep  grooves  formed  for  them 
upon  the  sphenoidal  fossa,  reaching  from  the  foramen  spinosum  to  the  point  of  the  great 
ala  of  the  sphenoid  bone.  Lastly,  the  distribution  of  the  middle  meningeal  veins  is  sim- 
ilar to  that  of  the  corresponding  artery. 

The  internal  meixillary  vein  is  also  joined  by  the  inferior  dental,  by  the  deep  temporal, 
by  the  pterygoid,  and  by  the  posterior  masseteric  veins.  All  of  these  veins  communicate 
with  a  very  large  and  important  venous  plexus,  the  pterygoid  plexus,  situated  between 
the  temporal  and  external  pterygoid  muscles,  and  between  the  two  pterygoid  muscles. 
In  this  plexus,  which  communicates  freely  with  the  alveolar  plexus,  so  freely,  indeed, 
that  they  may  be  regarded  as  forming  but  a  single  plexus,  the  internal  maxillary  vein 
commences  and  joins  the  temporal  vein,  behind  the  neck  of  the  condyle  of  the  lower  jaw. 

The  temporo-maxillary  trunk,  thus  formed  by  the  junction  of  the  temporal  with  the 
internal  maxillary  vein,  is  much  larger  than  the  former  vein,  and  continues  its  course 
through  the  substance  of  the  parotid  gland  ;  it  is  joined  directly  by  some  parotid  veins, 
by  the  posterior  and  anterior  auricular  veins,  and,  lastly,  by  the  transverse  veins  of  the  face. 
The  last-named  veins  form,  between  the  parotid  gland  and  the  masseter  muscle  (j,  fig. 
219),  between  that  muscle  and  the  ramus  of  the  lower  jaw,  and  around  the  temporo-max- 
illary articulation,  a  very  large  plexus,  named  the  masseteric  plexus,  which  communicates 
freely  with  the  pterygoid  plexus  through  the  sigmoid  notch. 

Termination  of  the  Temporo-maxillary  Trunk. — Most  commonly  the  temporo-maxillary 
vein  or  trunk  terminates  directly  in  the  external  jugular  vein  (h) ;  at  other  times  it  enters 
the  internal  jugular,  and  then  there  is  merely  a  trace  of  the  external  jugular,  which  is 
formed  principally  by  the  superficial  branches  of  the  occipital  vein,  and  by  some  commu- 
nicating branches  from  the  anterior  jugular.  In  some  cases,  the  temporo-maxillary  vein 
is  almost  equally  divided  between  the  internal  and  external  jugulars ;  lastly,  it  is  some- 
times united  to  the  lingual  and  the  facial  vein :  when  it  ends  in  the  external  jugular,  it 
sends  to  the  internal  jugular  a  large  conmiunicating  branch  which  passes  above  the  di- 
gastric muscle. 

The  Posterior  Auricular  Vein. 
The  posterior  auricular  vein  follows  the  distribution  of  the  artery  of  that  name ;  it  re- 
ceives the  stylo-mastoid  vein,  and  enters  the  external  jugular,  or,  rather,  the  temporo- 
maxillary  vein,  which  does  not  take  the  name  of  external  jugular  until  after  it  is  joined 
by  this  vein. 

The  Occipital  Vein. 

The  occipital  vein  is  distributed  in  the  same  manner  as  the  occipital  artery ;  it  com- 
mences at  the  back  of  the  cranium,  passes  beneath  the  splenius  muscle,  and  is  joined 
opposite  the  mastoid  process  by  one  or  more  large  mastoid  veins,  which  come  from  the 
corresponding  lateral  sinus,  establishing  a  direct  and  free  communication  between  the 
venous  circulation  in  the  interior  and  exterior  of  the  cranium.  It  was  this  that  led  Mor- 
gagni  to  prefer  the  occipital  veins  for  the  purpose  of  bloodletting  in  apoplexy.  The  oc- 
cipital vein  ends  in  the  internal,  and  sometimes  in  the  external  jugular. 

The  Lingual  Veins. 

The  lingual  veins,  being  intended  for  a  contractile  organ,  the  circulation  in  which  is  on 
that  account  liable  to  be  much  interfered  with,  are  divided,  hke  the  veins  of  the  limbs, 
into  the  superficial  or  suh-mucous,  and  the  deep  veins. 

The  superficial  veins  of  the  dorsum  of  the  tongue,  which  are  generally  named  the  lingual 
veins,  occupy  the  dorsal  region  of  the  tongue,  ramifying  in  a  remarkable  manner  between 
the  mucous  membrane  and  the  muscular  fibres  of  that  organ :  all  these  veins  open  into 
a  dorsal  or  superior  lingual  plexus,  which  is  situated  at  the  base  of  the  tongue,  and  is 
joined  by  a  great  number  of  veins  from  the  tonsils  and  epiglottis. 

The  satellite  vein  of  the  lingual  nerve  emanates  from  this  plexus,  accompanies  the  lin- 
gual nerve,  receives  some  branches  from  the  sub-lingual  glands  and  the  tissue  of  the 
tongue,  and  enters  the  facial  or  the  pharyngeal  vein,  or  terminates  directly  in  the  exter- 
nal jugular,  communicating  freely  with  the  ranine  veins. 

The  ranine  veins  are  the  superficial  veins  of  the  lower  surface  of  the  tongue.    They 


THE    PHARYNGEAL  VEIN,  ETC.  991 

are  seen  one  upon  each  side  of  the  fraenum,  where  they  form  a  ridge  beneath  the  mucous 
membrane.  Each  of  them  accompanies  the  corresponding  hypoglossal  nerve,  between 
the  genio-hyoglossus  and  hyoglossus  muscles,  and  terminates  either  in  the  common 
trunk  of  the  lingual  and  facial  veins,  or  directly  in  the  facial  vein. 

The  ranine  veins  communicate  upon  the  sides  of  the  tongue  with  a  very  large  plexus, 
the  vessels  composing  which  are  sometimes  provided  with  valves,  so  that  it  is  impossi- 
ble to  inject  it  in  a  direction  from  the  heart  towards  the  extremities  of  the  veins,  which, 
in  other  cases,  may  be  done  with  the  greatest  facility. 

Lastly,  the  lingual  veins,  properly  so  called,  are  extremely  small;  they  are  two  in 
number,  and  accompany  the  lingual  artery  throughout  the  whole  of  its  course.  Not  un- 
frequently  the  veins  of  the  tongue  terminate  directly  in  the  internal  jugular :  I  have  seen 
them  open  into  the  anterior  jugular. 

The  Pharyngeal  Vein  and  Pharyngeal  Plexus. 

The  Pharyngeal  Plexus. — In  making  the  section  already  described  for  examining  the 
pharynx,  we  observe  round  the  back  of  that  organ  a  considerable  venous  plexus,  which 
forms  loops  or  rings  for  embracing  the  pharynx ;  several  meningeal  branches,  and  some 
derived  from  the  vidian  and  spheno-palatine  veins,  open  into  this  plexus  ;  from  which  a 
variable  number  of  pharyngeal  branches  arise,  and  terminate  by  a  common  trunk,  or  by 
several  distinct  branches,  in  the  lingual  vein,  sometimes  in  the  facial  or  the  inferior  thy- 
roid, and  frequently  in  the  internal  jugular. 

Besides  this  plexus,  which  may  be  called  the  superficial  pharjTigeal  plexus,  an  ex- 
tremely dense  network  is  found  beneath  the  mucous  membrane,  from  which  branches 
proceed  to  join  with  those  that  arise  from  the  superficial  plexus  just  described 

The  Superior  and  the  Middle  Thyroid  Veins. 

The  superior  thyroid,  or  thyro-laryngeal  vein,  commences  upon  the  thyroid  gland  by 
branches  corresponding  to  the  thyroid  arteries,  and  upon  the  larynx  by  branches  corre- 
sponding to  the  ramifications  of  the  superior  laryngeal  artery.  The  thyroid  and  laryn- 
geal branches  unite  and  end  in  the  internal  jugular  vein,  opposite  the  upper  part  of  the 
larynx ;  they  perhaps  end  more  frequently  in  the  common  trunk  of  the  facial  and  lingual 
veins.  It  is  not  uncommon  to  find  the  superior  laryngeal  branch  terminating  directly 
either  in  one  or  the  other  of  these  veins,  or  in  the  anterior  jugular. 

The  middle  thyroid  vein  arises  from  the  lower  part  of  the  lateral  lobe  of  the  thyroid 
gland,  and  is  joined  by  some  branches  from  the  larynx  and  the  trachea.  By  their  union 
they  form  a  trunk,  which  ends  in  the  lower  part  of  the  internal  jugular  vein.  The  con- 
stant existence  of  this  vein  explains  in  some  degree  a  rather  frequent  variety  in  the  ar- 
teries of  the  thyroid  gland,  viz.,  the  existence  of  a  middle  thyroid  artery  given  off  by  the 
common  carotid.  Not  unfrequently  there  are  two  middle  thyroid  veins  on  each  side 
These,  as  well  as  all  the  other  thyroid  veins,  are  much  enlarged  in  goitre 

The  Veins  of  the  Diplo'e. 

To  complete  the  description  of  the  vessels  of  the  head,  it  only  remains  for  me  to  no- 
tice the  diploic  veins,  or  the  proper  veins  of  the  bones  of  the  cranium.  They  were  first 
described  by  M.  Dupuytren,  in  his  inaugural  thesis,  under  the  name  of  venous  canals  of 
the  bones  :  they  were  afterward  figured  by  M.  Chaussier  (Traite  de  V Encephale),  and,  to- 
gether with  their  principal  varieties,  they  have  lately  been  represented  with  uncommon 
accuracy  by  M.  Breschet,  in  his  admirable  work  upon  the  veins. 

In  the  substance  of  the  cranial  bones  there  are  found  ramified  venous  canals,  which 
are  occupied  by  veins,  having  only  their  internal  membrane,  the  bony  canals  themselves 
serving  for  an  external  coat.  These  venous  canals  are  not  exclusively  confined  to  the 
bones  of  the  cranium :  they  exist  in  all  spongy  bones,  and  even  in  compact  bones  ;  but, 
while  the  canals  are  found  in  the  entire  substance  of  spongy  bones,  in  the  compact  part 
of  the  long  bones  they  are  situated  near  the  medullary  canal. 

The  venous  canals  of  the  bones  of  the  cranium  vary  much  in  their  size,  and  in  the 
extent  to  which  they  are  distributed :  they  are  independent  of  each  other  as  long  as  the 
cranial  bones  remain  distinct  and  separable  ;  but  they  almost  always  communicate  when, 
in  the  progress  of  age,  those  bones  become  united  together.  They  get  larger  and  larger 
as  life  advances,  and  their  size  is  indirectly  proportioned  to  the  number  of  their  ramifi- 
cations :  they  sometimes  present  ampullae  or  dilatations,  and  at  other  times  are  suddenly 
interrupted,  and  terminate  in  culs-de-sac,  reappearing  again  farther  on,  or  ceasing  alto- 
gether :  these  peculiarities  depend  upon  the  venous  canal  opening  at  different  points 
into  the  middle  meningeal  veins.  Moreover,  these  venous  canals  communicate  by  a 
number  of  orifices  of  different  sizes,  either  in  the  interior  of  the  cranium  with  the  me- 
ningeal veins,  and  with  the  sinuses  of  the  dura  mater,  or  on  the  exterior  with  the  veins 
which  lie  in  contact  with  the  bones  of  the  scull. 

In  some  heads  of  old  subjects,  these  canals  are  found  blended  with  the  furrows  for 
the  branches  of  the  meningeal  arteries  ;  those  furrows-  themselves  present  some  large 
foramina,  which  open  into  the  cranium  in  various  nlaces. 


69^  ANGEIOLOGY. 

In  new-born  infants  there  are  no  venous  canals,  properly  so  called ;  but  the  whole 
substance  of  the  bones  is  traversed  by  a  venous  network,  which  may  be  seen  when  its 
constituent  veins  are  naturally  injected  with  blood,  or  when  they  have  been  filled  with 
mercury,  by  which  as  delicate  a  network  of  vessels  can  be  shown  in  the  diploe  as  in  in- 
jections of  the  soft  parts.  At  this  period  all  the  cells  of  the  bones  are  filled  with  venous 
blood. 

On  the  roof  of  the  cranium  the  canals  of  the  diploe  are  divided  into  the  frontal,  tempo- 
ral, parietal,  and  occipital. 

The  frontal  diploic  canals  are  two  in  number,  one  on  the  right,  the  other  on  the  left 
side  :  they  commence  by  numerous  ramifications  upon  the  upper  part  of  the  frontal 
bones,  increase  in  size  as  they  approach  the  lower  part  of  the  roof  of  the  scull,  commu- 
nicate with  each  other  by  transverse  branches,  and  also  with  the  periosteal  or  the  me- 
ningeal veins,  open  externally  by  vascular  foramina,  and  then  enter  the  supra-orbital 
and  frontal  veins. 

The  temporo-parietal  diploic  canals  are  divided  into  anterior  and  posterior  :  they  corre- 
spond to  the  furrows  which  contain  the  ramifications  of  the  meningeal  artery,  and  open 
into  those  furrows  by  a  great  number  of  foramina,  which  become  very  distinct  in  advanced 
life  :  they  also  communicate  with  the  deep  temporal  veins  on  the  exterior  of  the  scull. 

The  occipital  diploic  canals,  two  in  number,  a  right  and  a  left,  communicnte  with  each 
other  by  a  great  number  of  branches,  and  open  below  into  the  occipital  veins. 

Summary  of  the  Distribution  of  the  Veins  of  the  Head. 

Circulation  in  the  Brain. — Corresponding  to  two  of  the  arterial  trunks,  the  common 
carotids,  which  convey  blood  to  the  head  and  neck,  there  are  six  veins,  to  return  it  back 
to  the  heart  from  the  same  parts,  viz.,  the  two  internal,  the  two  external,  and  the  two 
anterior  jugulars.  This  arrangement  tends  to  prevent  interruption  of  the  venous  circu- 
lation in  the  head,  which,  from  so  many  causes,  is  liable  to  be  disturbed.  The  external 
and  anterior  jugular  veins  belong  to  the  sub-cutaneous  venous  system,  and  may  be  re- 
garded as  supplementary  veins  which  have  no  corresponding  arteries,  and  which  would 
be  sufficient  of  themselves  to  carry  on  the  venous  circulation ;  and  as  the  veins  of  the 
right  and  left  sides  communicate  very  freely  with  each  other,  it  follows  that  one  of  them 
would  suffice  to  return  the  blood  from  the  head.  It  will  be  seen  hereafter,  when  de- 
scribing the  veins  of  the  spine,  that  the  obliteration  of  all  the  six  jugular  veins  would 
not  of  necessity  be  followed  by  interruption  of  the  venous  circulation  in  the  cranium. 
Lastly,  it  is  important  to  observe,  that  the  external  and  anterior  jugulars  open  into  the 
sub-clavian  vein,  while  the  internal  jugular  joins  the  inner  end  of  the  sub-clavian,  to 
form  the  brachio-cephalic  vein. 

We  have  seen  that  the  lower  part  of  the  internal  jugular  vein  represents  the  common 
carotid,  and  the  upper  part  of  it  the  internal  carotid ;  and  that  the  external  carotid  is 
represented  by  all  the  veins  of  the  face  and  neck,  which  open  into  the  internal  jugular 
either  by  a  common  trunk,  or  by  several  distinct  branches. 

The  cerebral  venous  system  is  remarkable  for  the  extreme  thinness  of  the  parietes 
of  the  veins  upon  the  brain,  and  for  the  existence  of  the  sinuses,  which  take  the  place 
of  the  venous  trunks,  and  differ  so  much  in  their  distribution  from  the  arteries.  The 
cerebral  veins  are  divided  into  the  ventricular  veins,  which  go  to  form  the  venae  Galeni, 
and  the  superficial  veins  of  the  brain.  All  of  them  run  towards  the  sinuses,  in  which  they 
terminate  in  succession  like  the  barbs  of  a  feather  upon  the  common  shaft,  but  do  not 
acquire  a  great  size.  From  the  absence  of  valves  at  their  orifices  into  the  sinuses,  the 
blood  may  regurgitate  into  them.  The  presence  of  the  spongy  areolar  tissue  at  the  or- 
ifices of  these  veins,  together  with  their  oblique  course  through  the  walls  of  the  sinus, 
must  diminish  this  regurgitation :  the  communication  of  the  cerebral  veins  with  each 
other,  and  the  continuity  of  the  several  sinuses,  explain  the  varied  means  contrived  for 
carrying  on  the  cerebral  circulation,  which  can  only  be  interrupted  by  obliteration  of  the 
lateral  sinuses. 

Lastly,  the  position  of  the  principal  sinuses  opposite  the  fissures  between  the  great  di- 
visions of  the  encephalon,  and  the  resisting  nature  of  the  walls  of  the  sinuses  themselves, 
prevent  the  fatal  effects  which  might  otherwise  ensue  from  compression  produced  by 
obstruction  of  the  venous  circulation. 

Circulation  in  the  Parietes  of  the  Cranium. — In  the  parietes  of  the  cranium  we  find  the 
veins  of  the  dura  mater,  the  veins  of  the  diploe,  the  periosteal  veins,  and  the  veins  of 
the  hairy  scalp.  The  numerous  communications  existing  between  these  four  systems 
of  veins,  and  the  direct  communications  established  between  the  sinuses  of  the  dura 
mater  and  the  veins  on  the  exterior  of  the  scull,  are  worthy  of  particular  attention.  I 
would  observe  that  the  principal  veins  of  the  scalp,  like  the  arteries  of  the  same  part, 
are  situated  between  the  skin  and  the  epicranial  aponeurosis.  I  have  ascertained  the 
existence  of  free  and  frequent  anastomoses  among  these  veins.  As  at  the  back  of  the 
cranium  there  is  a  very  free  communication  between  the  occipital  vein  and  the  lateral 
sinus  by  means  of  a  large  vein,  so,  also,  along  the  superior  longitudinal  groove,  and  op 
posite  the  sutures  upon  the  base  of  the  scull  (through  most  of  the  foramina  found  in  that 


THE  DEEP  VEINS  OP  THE  UPPER  EXTKEMITY.  593 

ntoation),  an  uninterrupted  communication  is  established  between  the  veins  within  and 
^ose  outside  the  cranium. 

Venous  Circulation  of  the  Face. — ^All  the  veins  of  the  face  and  of  the  parietes  of  the 
cranium  end  in  two  principal  trunks,  the  facial  and  the  temporal.  The  facial  vein  cor« 
responds  to  a  part  of  the  internal  maxillary  artery,  to  a  part  of  the  ophthalmic  artery, 
and  to  the  facial  artery  properly  so  called.  One  of  the  most  remarkable  circumstances 
connected  with  the  distribution  of  the  facial  vein  is  the  communication  between  it  and 
the  cavernous  sinus,  established  at  the  inner  angle  of  the  orbit  by  means  of  the  ophthal- 
mic vein,  so  that  the  veins  on  the  inside  and  on  the  outside  of  the  cranium  are  most  in 
timately  connected.* 

The  temporal  vein  represents  the  temporal  artery,  a  part  of  the  internal  maxillary  ar- 
tery, and  the  upper  part  of  the  external  carotid,  and  returns  the  blood  from  the  entire 
side  of  the  head. 

With  regard  to  the  veins  of  the  tongue,  we  should  remark  the  existence  of  two  sub- 
mucous veins,  corresponding  to  the  sub-cutaneous  veins  in  the  limbs,  and  intended  to 
return  the  blood,  instead  of  the  deep  veins  of  the  tongue,  during  the  contractions  of  that 
organ. 

The  size  of  the  superior  middle  thyroid  veins,  their  number,  which  exceeds  that  of 
the  arteries,  and  their  free  anastomoses  with  the  inferior  thyroid  veins,  render  them  an 
important  medium  of  circulation  when  the  passage  of  the  blood  from  the  head  is  obstruct 
ed,  and,  at  the  same  time,  a  diverticulum  in  great  impediments  to  the  circulation. 

The  irregularity  which  exists  in  the  relative  size  of  the  internal,  external,  and  ante- 
rior jugular  veins,  and  also  in  the  distribution  of  the  veins  of  the  head  between  these 
three  trunks,  proves  that,  in  the  venous  as  well  as  in  the  arterial  system,  the  origin  or 
termination  of  the  vessels  is  of  little  importance,  and  that,  after  the  venous  system  of 
any  part  is  once  formed,  it  matters  but  little  with  which  of  the  great  vascular  trunks  it 
is  connected. 

Lastly,  the  free  communications  which  exist  between  all  the  preceding  veins  afford 
sufficient  evidence  that  but  little  interest  need  be  attached  to  their  termination  in  one 
or  another  of  the  principal  venous  trunks. 

The  Deep  Veins  of  the  Upper  Extremity. 
The  veiTts  of  the  upper  extremity  are  divided  into  the  deep  and  the  superficial  or  sub- 
cutaneous. 

The  Palmar^  Radial,  Ulnar,  Brachial,  and  Axillary  Veins. 

The  deep  veins  of  the  upper  extremity  exactly  follow  the  course  of  the  arteries,  form 
their  venae  comites,  and  take  the  same  names  :  there  are  almost  always  two  to  each  ar- 
tery. The  large  venous  trunks  alone  form  exceptions  to  this  rule.  Thus,  there  are  two 
superficial  and  two  deep  palmar  veins  ;  two  deep  radial  and  two  deep  ulriar  veins  ;  we  also 
find  two  brachial  veins  ;  but  there  is  only  one  axillary  and  one  suh-clavian  vein.  All  these 
venae  comites  receive  branches  formed  by  the  union  of  still  smaller  ones,  which  are  them- 
selves the  vense  comites  of  the  ramifications  of  the  arteries,  there  being  two  veins  with 
each  small  artery.  The  sub-clavian  vein,  however,  is  an  exception  to  this,  for  it  does 
not  receive  all  the  veins  which  correspond  to  the  branches  of  the  sub-clavian  artery ; 
while,  on  the  other  hand,  it  receives  other  veins  that  are  totally  unconnected  with  the 
distribution  of  that  artery.  I  ought  to  allude,  in  this  place,  to  a  mode  of  termination  of 
the  collateral  veins,  which  is  frequently  observed,  especially  in  the  brachial  vein.  The 
circumflex  veins,  for  example,  instead  of  entering  the  brachial  vein  directly,  terminate 
in  a  collateral  branch,  which  runs  parallel  to  the  brachial  vein,  like  a  canal  running  along- 
side a  river,  and  communicates  with  that  vein  above  and  below.  Several  large  veins 
have  these  collateral  caneils,  which  establish  a  communication  between  different  points 
of  their  length.  Thus,  I  have  seen  a  venous  trunk  proceed  from  the  external  jugular,  de- 
scend through  the  brachial  plexus  of  nerves,  and  enter  the  lower  part  of  the  axillary  vein. 

The  deep  veins,  moreover,  communicate  freely  and  frequently  with  the  superficial 
veins.  They  are  also  provided  with  valves,  like  the  superficial  veins,  and,  it  appears, 
even  with  a  greater  number  :  an  injection  thrown  from  the  heart  towards  the  extrem- 
ities will  not  enter  more  readily  into  one  than  into  the  other  set.  We  always  find  two 
valves  at  the  mouth  of  a  small  vein  where  it  opens  into  the  larger  trunk ;  and  it  is  a  re- 
markable fact  that,  while  the  valves  situated  in  the  course  of  the  veins  are  sometimes 
passed  by  the  injection,  those  which  are  placed  at  the  mouths  of  the  small  veins  are 
scarcely  ever  overcome. 

The  Sub-clavian  Vein. 
The  term  suh-clavian  is  generally  given  to  all  that  portion  of  the  brachial  venous  trunk 

*  The  study  of  these  anastomoses  ought  to  lead  us  again  to  have  recourse  to  those  local  venesections  which 
have  fallen  into  disuse  since  the  discovery  of  the  circulation  ;  and  it  will  enable  us  to  determine,  on  anatomi- 
cal grounds,  the  proper  places  at  which  they  should  be  performed.  Thus,  it  appears  to  me  that  we  might  ad- 
vantageously introduce  into  jiractice  bleeding  from  the  angular  vein  in  diseases  of  the  eye  ;  from  over  the  mas- 
toid region,  and  the  point  wl'.ch  corresponds  to  the  junction  of  the  longitudinal  with  the  lambdoidal  suture,  in 
cerebral  affections;  and  bleeding  from  the  ranine  vein  in  diseases  of  the  pharynx. 

4  F 


694  ANGEIOLOGY. 

which  extends  from  the  vena  cava  superior  to  the  scaleni  muscles ;  but  this  vein  may 
be  described  more  naturally,  as  being  limited  internally  by  the  brachio-cephalic  vein,  or, 
rather,  by  the  junction  of  the  internal  jugular  vein  with  the  venous  trunk  of  the  upper 
extremity,  and  externally  by  the  clavicle,  or,  rather,  by  the  costo-coracoid,  or  sub-cla- 
vian  aponeurosis.  If  the  sub-clavian  veins  be  thus  defined,  they  will  be  of  equal  length 
on  both  sides  ;  and  the  left  vein,  and  even  the  right  vein  also,  will  be  shorter  than  the 
corresponding  artery. 

The  direction  of  the  sub-clavian  veins  differs  much  from  that  of  the  arteries  :  we  have 
Seen  that  the  sub-clavian  arteries  describe  a  curve  over  the  apex  of  the  lung,  with  its 
concavity  turned  downward ;  the  sub-clavian  veins,  on  the  contrary,  proceed  directly 
outward  as  far  as  the  first  rib,  over  which  they  bend,  so  that  they  resemble  the  cord  of 
the  arc  described  by  the  sub-clavian  artery.  We  have  seen,  also,  that  the  inferior  thy- 
roid vein,  the  internal  mammary,  the  vertebral,  the  supra-scapular,  the  posterior  scapu- 
lar, the  deep  cervical,  and  the  left  superior  intercostal  veins,  enter  not  into  the  sub-cla- 
vian, but  either  into  the  superior  vena  cava,  or  into  the  brachio-cephalic  vein.  The  right 
superior  intercostal  vein,  when  it  exists,  that  is  to  say,  when  the  branches  which  should 
form  it  do  not  terminate  separately  in  the  vena  azygos,  is  the  only  one  of  the  veins  cor- 
responding to  the  branches  of  the  sub-clavian  artery  which  opens  into  the  sub-clavian  vein 

The  external  jugular,  the  anterior  jugular,  and  a  small  branch  from  the  cephalic  vein 
of  the  arm,  also  terminate  in  the  sub-clavian  vein.  It  would  therefore,  in  some  respects, 
be  proper  to  describe  the  external  and  anterior  jugulars  in  connexion  with  the  sub-cla- 
vian vein,  instead  of  with  the  internal  jugular.  I  would  remark,  that  the  external  and 
anterior  jugulars  frequently  terminate,  not  in  the  sub-clavian  vein,  but  at  the  point  where 
it  ends  in  the  brachio-cephaUc  vein,  in  front  of  the  internal  jugular. 

Relations. — In  front  of  the  sub-clavian  vein  is  situated  the  clavicle,  which  is  separated 
from  the  vein  only  by  the  sub-clavian  muscle,  so  that  this  vessel  may  be  wounded  in 
fractures  of  the  clavicle  :  a  very  dense  fibrous  sheath  binds  it  down  to  the  sub-clavius 
muscle  ;  and  it  perforates  the  costo-coracoid  or  sub-clavian  aponeurosis,  which  adheres 
to  it,  and  keeps  it  open  when  cut  across  ;  behind  the  vein  is  the  sub-clavian  artery,  from 
which  it  is  separated,  towards  the  inner  part,  by  the  scalenus  anticus  ;  below,  it  is  in  re- 
lation with  the  pleura  and  with  the  first  rib,  on  which  there  is  a  corresponding  but  slight 
depression  ;  above,  it  is  covered  by  the  cervical  fascia,  which  separates  it  from  the  skin : 
a  considerable  swelling  is  often  seen  in  this  region  when  the  venous  circulation  is  ob- 
structed. 

The  Superficial  or  Sub-cutaneous  Veins  of  the  Upper  Extremity. 
The  sub-cutaneous  veins  of  the  upper  extremity  belong  essentially  to  the  skin  and  to  the 
subjacent  adipose  tissue,  since  all  the  branches  from  the  muscles  enter  the  deep  veins. 
The  superficial  are  larger  than  the  deep  veins,  with  which  they  communicate  freely  at  a 
great  number  of  points  ;  and  it  may  be  remarked,  that  the  size  of  the  one  set  of  vessels 
is  always  inversely  proportioned  to  that  of  the  other  set.  We  proceed  to  describe  them 
in  succession  in  the  hand,  the  forearm,  and  the  arm. 

The  Superficial  Veins  of  the  Hand. 

All  the  largest  veins  of  the  hand  are  situated  upon  its  dorsal  aspect ;  and  it  is  worthy 
of  notice,  that  the  largest  arteries,  on  the  contrary,  occupy  the  palm  of  the  hand.  If  the 
superficial  veins  had  existed  on  the  palmar  aspect,  the  venous  circulation  would  have 
been  impeded  whenever  the  hand  was  used  in  prehension.  Entering  into  the  large  sub- 
cutaneous network  of  veins  situated  upon  the  back  of  the  hand  are  several  branches, 
which  constitute  the  superficial,  external,  and  internal  collateral  veins  of  each  fingei  ,  they 
occupy  the  outer  and  inner  borders  of  the  dorsal  surface  of  the  fingers,  and  comnmni- 
cate  frequently  on  the  dorsal  surface  of  each  phalanx  and  around  the  phalangeal  artic- 
xilations,  but  not  upon  the  articulations  themselves. 

Opposite  the  lower  part  of  each  interosseous  space,  these  collateral  veins  unite  at  an 
acute  angle,  just  as  the  digital  arteries  bifurcate  at  the  same  point.  All  the  superficial 
digital  veins  ascend  vertically  between  the  metacarpo-phalangeal  articulations,  which 
they  seem  to  avoid,  and  then  enter  into  the  convexity  of  a  very  irregular  venous  arch, 
■which  is  formed  by  a  series  of  loops,  at  each  of  the  junctions  of  which  one  of  the  digital 
veins  is  seen  to  terminate. 

From  the  concavity  of  this  irregular  arch,  which  is  turned  upward,  are  given  off  a 
/greater  or  less  number  of  ascending  branches,  which  are  sometimes  formed  directly  by 
■  the  junction  of  the  digital  veins,  without  the  intervention  of  an  arch.  Among  these 
branches,  we  should  especially  notice  the  external  branch,  which  is  situated  nearest  to 
the  first  metacarpal  bone,  and  is  called  the  cephalic  vein  of  the  thumb;  also  the  innermost 
branch,  which  corresponds  to  the  fifth  metacarpal  bone,  and,  for  some  reason  not  very 
'.well  known,  has  been  named  the  vena  salvatella. 

The  Superficial  Veins  of  the  Forearm. 
"The  superficial  veins  are  much  more  numerous  on  the  anterior  than  on  the  posterior 


THE   SUPERFICIAL    VEINS    AT    THE    ELBOW,  ETC.  595 

aspect  of  the  foreann.  We  find  there  the  radial  vein  or  veins,  the  ulnar  vein,  and  the 
median  vein. 

The  superficial  radial  vein  (r,  in  the  representation  of  the  superficial  nerves  of  the  arm) 
is  the  continuation  of  the  cephalic  vein  of  the  thumb  ;  it  is  situated  along  the  outer  side 
of  the  carpus  and  of  the  radius,  and  it  soon  unites  with  some  branches  from  the  vena 
salvatella,  or  vi^ith  the  salvatella  itself  The  superficial  radial  vein  often  divides  into 
several  branches,  which  are  joined  by  others  from  the  venous  arch  at  the  back  of  the 
hand.  There  are  sometimes  two  superficial  radial  veins.  The  vein  or  veins  having 
reached  the  middle  of  the  forearm,  turn  forward  upon  the  outer  border  of  the  radius,  and 
then  continue  to  ascend  vertically  along  the  outer  side  of  the  anterior  surface  of  the  fore- 
arm, up  to  the  bend  of  the  elbow. 

The  ulnar  vein  {u)  commences  partly  from  the  vena  salvatella,  and  another  vein  on  the 
dorsal  region  of  the  forearm,  and  partly  from  some  branches  which  arise  from  the  lower 
part  of  the  back  of  the  forearm,  and  even  from  some  small  veins  proceeding  from  the 
thenar  and  hypothenar  eminences. 

The  branches  which  arise  from  the  vena  salvatella  and  the  back  of  the  wrist  pass  for- 
ward ;  the  other  branches  run  backward ;  the  common  trunk  or  trunks  resulting  from 
their  union  are  directed  at  first  vertically  upward,  parallel  with  the  superficial  radial 
vein,  then  somewhat  obliquely  forward,  to  anastomose  with  the  median  basilic  vein, 
above  the  bend  of  the  elbow.  When  there  is  a  second  or  posterior  ulnar  vein,  it  ends  in 
the  basilic  higher  up,  or  else  it  anastomoses  with  the  anterior  ulnar  vein. 

Between  the  anterior  radial  and  ulnar  veins  we  find  the  common  median  or  median  vein 
(m),  formed  by  the  anterior  veins  of  the  carpus  and  forearm.  There  may  be  more  than 
one  median  vein,  and  it  is  not  unfrequently  wanting,  in  which  case  its  place  is  supplied 
by  a  venous  network,  the  branches  from  which  enter  separately  into  the  radial  and  ulnar 
veins.  In  some  cases  its  place  is  supplied  by  an  additional  radial  vein,  and  at  other 
times  by  the  deep  veins. 

The  Stiperficial  Veins  at  the  Elbow. 

At  the  elbow  all  the  veins  are  on  the  anterior  aspect.  The  most  common  arrangement 
is  the  following  :  on  the  outer  side  we  find  the  upper  portion  of  the  radial  vein  or  veins  ; 
on  the  inner  sMe,  the  upper  portion  of  the  ulnar  vein  or  veins,  which  pass  in  front  of  the 
internal  condyle  of  the  humerus  ;  between  the  radial  and  ulnar  veins  is  the  median, 
which  divides  into  two  branches  :  one  external  (a),  which  unites  with  the  radial  to  form 
the  cephalic  vein  (c),  and  is  called  the  median  cephalic ;  the  other  internal  (e),  generally 
smaller,  but  more  superficied  than  the  preceding,  which  unites  with  the  ulnar  to  form  the 
basilic  vein  {b),  and  is  called  the  median  basilic. 

Several  varieties  are  observed  in  the  arrangement  of  the  veins  of  the  elbow ;  some- 
times the  common  median  vein  is  wanting  ;  but  then  its  cephalic  and  basilic  branches 
are  given  off  by  the  radial,  and  the  cephalic  vein  is  almost  always  very  small.  In  other 
cases  we  only  find  two  veins  at  the  bend  of  the  elbow,  viz.,  the  radial  and  the  ulnar, 
which  are  directly  continuous  with  the  cephalic  and  basilic.  I  once  saw  the  common 
median  vein  replaced  by  the  anterior  radial,  and  by  a  branch  from  one  of  the  deep  ulnar 
veins. 

The  Superficial  Veins  in  the  Arm. 

In  the  arm  there  are  only  two  superficial  veins,  an  external,  named  the  cephalic  vein, 
and  an  internal  or  basilic. 

The  cephalic  vein  (c)  is  formed  by  the  junction  of  the  radial  with  the  median  cephalic 
vein,  which  junction  may  occur  at  very  different  heights.  It  ascends  vertically  along 
the  outer  border  of  the  biceps ;  then,  running  a  Uttle  inward,  it  gains  the  furrow  be- 
tween the  deltoid  and  pectoralis  major,  passes  over  the  summit  of  the  coracoid  process, 
above  or  in  front  of  which  it  curves  backward,  so  as  to  enter  the  axillary  vein  immedi- 
ately below  the  clavicle.  From  this  curve  the  cephalic  vein  gives  off  a  branch,  which 
passes  in  front  of  the  clavicle,  crosses  at  right  angles  over  the  middle  of  that  bone,  and 
enters  the  sub-clavian  vein.  Not  unfrequently  the  cephalic  vein  is  replaced  by  a  very 
small  branch. 

The  internal  vein  of  the  arm,  which  is  called  the  basilic  vein  (i),  is  generally  larger 
than  the  cephalic.  It  is  formed  by  the  junction  of  the  ulnar  with  the  median  basilic  vein, 
passes  at  first  obliquely  backward,  and  then  vertically  upward,  in  front  of  the  internal 
intermuscular  septum,  and  enters  either  the  brachial  or  the  axillary  vein. 

General  Remarks  upon  the  Superficial  Veins  of  the  Upper  Extremity. 
From  the  preceding  description,  it  follows  that  the  cephalic  vein  forms  the  continua- 
tion of  the  radial,  which  is  itself  the  continuation  of  the  cephalic  vein  of  the  thumb,  and 
that  the  basilic  is  a  prolongation  of  the  ulnar,  which  is  a  continuation  of  the  vena  salva- 
tella. The  median  vein,  placed  as  it  is  between  the  radial  and  ulnar  veins,  bifurcates 
so  as  to  tei-minate  equally  in  the  two  latter  veins,  and  estabhshes  a  free  anastomosis  be- 
tween them.  •  , 


998  ANGEIOLOGY. 

The  anastomoses  of  the  several  sub-cutaneous  veins  together  are  very  numeroois,  and 
enable  them  mutually  to  supply  the  place  of  each  other.  The  anastomoses  betvireen  the 
sub-cutaneous  and  deep  veins  are  not  less  numerous. 

Thus,  the  superficial  collateral  veins  of  the  fingers  communicate  with  the  deep  collat- 
eral veins  :  communications  exist  between  the  superficial  and  deep  veins  of  the  carpus  ; 
very  large  communications  exist  between  the  two  sets  of  vessels  at  the  bend  of  the  el- 
bow, so  that,  in  fact,  they  are  continuous  with  each  other ;  thus,  the  superficial  radial 
vein  is  sometimes  continuous  with  one  of  the  deep  radials,  and  the  median,  as  it  divides 
into  the  median  basilic  and  median  cephalic,  occasionally  sends  a  very  large  branch  to 
the  brachial.  In  one  case,  where  the  median  vein  was  wanting,  I  found  that  the  ulnar, 
the  deep  interosseous,  and  the  deep  radial  veins,  formed  a  plexus,  which  gave  oflT  two 
branches,  an  external  to  the  cephalic,  and  an  internal,  which  formed  the  deep  brachial 
vein.  The  superficial  ulnar  veins  often  communicate  freely  with  the  deep  ulnar,  beneath 
the  muscles  attached  to  the  internal  condyle. 

Along  the  arm,  the  basilic  vein  communicates  with  one  of  the  brachial  veins  by  several 
transverse  branches.  Not  unfrequently  the  basilic  vein  communicates  with  the  brachial 
by  a  very  delicate  branch,  which  forms  a  lateral  canal. 

Valves. — ^The  valves  are  more  numerous  in  the  deep  than  in  the  superficial  veins  ; 
they  increase  in  number  as  we  approach  the  upper  part  of  the  arm,  and  are  much  more 
numerous  in  the  basilic  than  in  the  cephalic  vein.  There  are  three  in  that  part  of  the 
cephalic  which  corresponds  to  the  furrow  between  the  deltoid  and  the  pectoralis  major. 
There  is  one  at  the  opening  of  the  cephalic  into  the  axillary  ;  another  at  the  opening  of 
the  basilic  into  the  brachial ;  all  the  small  veins  which  enter  the  cephalic  and  basilic,  as 
well  as  those  which  terminate  in  the  deep  veins,  are  also  provided  at  their  openings 
with  valves,  which  prevent  the  regurgitation  of  the  blood  during  life,  and  the  passage  of 
an  injection  from  the  heart  towards  the  extremities. 

General  Relations. — The  sub-cutaneous  veins  are  separated  from  the  skin  by  the  super- 
ficial  fascia,  and  by  the  layer  of  fat  above  it.  The  median  basilic  is  the  only  exception, 
for  it  is  in  contact  with  the  skin,  at  least  in  the  majority  of  subjects. 

The  sub-cutaneous  veins  must  be  carefully  distinguished  from  the  cutaneous  veins,  prop- 
erly so  called,  which  are  in  contact  with  the  true  skin,  or  even  ramify  in  its  substance, 
and  which  are  sometimes  of  considerable  size,  especially  in  the  neighbourhood  of  certain 
tumours. 

From  the  relation  of  the  median  basilic  vein  with  the  brachial  artery,  over  which  it 
crosses  at  a  very  acute  angle,  and  from  which  it  is  separated  only  by  the  fibrous  expan- 
sion from  the  tendon  of  the  biceps,  it  follows,  that  in  emaciated  persons  the  vein  is  al- 
most in  contact  with  the  artery ;  so  that,  in  bleeding  from  the  median  basilic,  if  the  vein 
be  perforated  quite  through,  the  artery  may  be  wounded.  The  practical  rules  to  be  de- 
rived from  this  anatomical  fact  are,  in  the  first  place,  to  avoid  bleeding  in  the  median 
basilic  as  much  as  possible,  and  whenever  it  must  be  chosen,  to  open  it  either  below 
or  above  the  point  where  it  crosses  over  the  artery. 

In  the  description  of  the  lymphatics  and  nerves  of  the  arm,  I  shall  point  out  their  re- 
lations with  the  superficial  veins.  I  may  now  state,  however,  that  the  musculo-cutane- 
ous  nerve  passes  behind  the  median  cephalic  vein,  and  that  the  internal  cutaneous  di- 
vides into  several  branches,  some  of  which  pass  in  front,  and  others  behind  the  median 
basilic  vein. 


THE  INFERIOR  OR  ASCENDING  VENA  CAVA  AND  ITS  BRANCHES. 

The  Inferior  Vena  Cava  —  the  Lumbar  or  Vertebro-lumbar  Veins  —  the  Renal — the  Middle 
Supra-renal — the  Spermatic  and  Ovarian — the  Inferior  Phrenic. — TVie  Portal  System  of 
Veins — the  Branches  of  Origin  of  the  Vena  Porta — the  Vena  Porta — the  Hepatic  Veins. 
— The  Common  Iliacs  —  the  Internal  Iliac  —  the  Hemorrhoidal  VeiTis  and  Plexuses  —  the 
Pelvic  Veins  and  Plexuses  in  the  Male  and  in  the  Female. — The  Deep  Veins  of  the  Lower 
Extremity  —  the  Plantar,  Posterior,  Tibial,  Peroneal,  Dorsal,  Anterior  Tibial,  and  Pop- 
liteal— the  Femoral  —  the  External  Iliac.  —  The  Superficial  Veins  of  the  Lower  Extremity 
— the  Internal  Saphenous — the  External  Saphenous. 

The  vcTia  cava  inferior  or  ascendens,  or  the  abdominal  vena  cava  {I,  fig.  222),  is  the  large 
venous  trunk  which  returns  the  blood  from  all  the  parts  below  the  diaphragm  to  the 
heart. 

It  is  formed  below  by  the  junction  of  the  two  common  iliac  veins  (n  n),  opposite  the 
mtervertebral  substance  between  the  fourth  and  fifth  lumbar  vertebras ;  it  passes  verti- 
cally upward,  and,  having  reached  the  lower  surface  of  the  liver,  inclines  a  little  towards 
the  right  side,  to  gain  the  groove  formed  for  it  in  the  posterior  border  of  that  organ.  At 
the  upper  end  of  that  groove  the  vena  cava  inferior  perforates  the  tendinous  opening  in 
the  diaphragm,  and  also  the  fibrous  layer  of  the  pericardium,  which  is,  as  it  were,  blend 
ed  with  the  cordiform  tendon  at  this  point ;  the  vein  then  curves  suddenly  to  the  left, 
and  opens  (r,  fig.  192)  horizontally  into  the  posterior  inferior  part  of  the  right  auricle. 


THE    VERTEBRO-liUMBAU   VEINS,   ETC.  597 

It  is  larger  than  the  vena  cava  superior,  but  is  not  of  uniform  caliber  throughout ;  for 
example,  it  increases  in  size  in  a  marked  degree  immediately  above  the  renal  veins. 
The  vena  cava  inferior  presents  also  a  second  still  larger  dilatation  opposite  the  liver, 
vphere  it  is  joined  by  the  hepatic  veins  ;  in  comparison  w^ith  its  diameter  at  that  point, 
the  vena  cava  inferior  appears  to  be  slightly  contracted  as  it  passes  through  the  dia- 
phragm. 

Relations. — The  inferior  cava  is  in  contact  with  the  anterior  surface  of  the  vertebral 
column,  and  runs  throughout  the  whole  of  its  extent  along  the  right  side  of  the  aorta  ;  it 
inclines  somewhat  obliquely  to  the  right  as  it  is  about  to  pass  into  the  groove  on  the 
liver.  In  front  it  is  covered  by  the  peritoneum,  the  third  portion  of  the  duodenum,  the 
pancreas,  the  vena  portse,  which  crosses  it  at  a  very  acute  angle,  and  at  its  upper  part 
by  the  liver,  which  forms  a  semi-canal,  or  a  complete  canal  for  it. 

It  adheres  closely  to  the  margins  of  the  tendinous  opening  in  the  diaphragm,  and  to 
the  fibrous  layer  of  the  pericardium,  as  if  its  outer  coat  were  blended  with  those  struc- 
tures. 

The  serous  layer  of  the  pericardium  covers  the  vein,  but  the  fibrous  layer  does  not 
form  a  sheath  for  it.  The  relations  of  the  inferior  cava  with  the  liver  account  for  the 
erroneous  notion  of  some  old  anatomists,  that  this  organ  was  the  centre  from  which  all 
the  veins  of  the  body  proceeded. 

There  is  no  valve  in  the  inferior  cava ;  but  at  its  termination  we  find  the  Eustachian 
valve,  which  has  been  already  described  with  the  heart. 

Branches  of  Origin. — We  have  stated  that  the  junction  of  the  common  iliac  veins  con- 
stitutes the  origin  of  the  inferior  cava.  It  is  very  rare  to  find  these  veins  uniting  above 
the  intervertebral  disc  between  the  fourth  and  fifth  lumbar  vertebrae ;  but  in  some  few 
cases  the  junction  has  been  observed  to  take  place  opposite  the  renal  veins. 

Collateral  Branches. — The  vena  cava  inferior  receives  all  the  veins  corresponding  to 
the  branches  of  the  abdominal  aorta,  excepting  the  veins  from  the  alimentary  canal  and 
its  appendages,  of  which  it  only  receives  those  from  the  liver,  viz.,  the  hepatic  veins. 
All  the  abdominal  veins  which  do  not  open  directly  into  the  inferior  cava  unite  to  form 
a  large  venous  trunk,  called  the  vena  porta.  Thus,  the  vena  cava  inferior  receives  the 
renal,  the  spermatic  or  ovarian,  the  lumbar,  the  supra-renal,  and  the  inferior  phrenic 
veins  ;  while  the  superior  and  inferior  mesenteric,  the  splenic,  the  pancreatic,  and  the 
gastric  veins  open  into  the  vena  portae.  It  may  still  be  said,  however,  that  the  vena 
cava  inferior  receives  all  the  abdominal  veins ;  for,  in  fact,  the  veins  of  the  portal  sys- 
tem terminate  in  the  vena  cava  through  the  medium  of  the  hepatic  veins.  The  portal 
system  is,  therefore,  an  appendage  to  the  inferior  cava.  For  this  reason,  and  also  for 
the  sake  of  economizing  subjects,  I  shall  not  describe  the  vena  portae  and  its  branches 
until  I  have  noticed  the  collateral  veins  of  the  vena  cava  inferior. 

The  Lumbar  or  Vertebro-lumbar  Veins. 

The  vertebro-lumbar  veins  are  three  or  four  on  each  side,  and  correspond  to  the  arteries 
of  the  same  name  ;  they  have  two  branches  of  origin  :  an  external  or  abdominal  branch, 
which  represents  the  intercostal  veins,  and  a  posterior  or  dorso-spinal  branch,  which  is 
itself  formed  by  the  union  of  two  other  branches ;  one  muscular  or  cutaneous,  which  com- 
mences in  the  muscles  and  integuments,  and  the  other  a  proper  spinal  branch,  which 
forms  part  of  the  rachidiau  venous  system,  to  be  hereafter  described. 

By  the  junction  of  these  two  branches  a  lumbar  vein  is  formed,  which  runs  forward 
and  inward  in  the  groove  on  the  body  of  the  corresponding  lumbar  vertebra,  and  enters 
the  vena  cava  at  a  right  angle.  The  left  lumbar  veins  are  longer  than  the  right,  in  con- 
sequence of  the  vena  cava  being  situated  towards  the  right  side  of  the  vertebral  column  • 
they  pass  under  the  aorta. 

The  Renal  Veins. 

The  renal  veins  are  remarkable  for  their  size,  and  occasion  a  great  increase  in  the 
diameter  of  the  inferior  cava,  above  the  point  where  they  open  into  it ;  they  are  of  un- 
equal size  on  the  two  sides,  and  are  unequal  in  length,  on  account  of  the  vena  cava  be- 
ing placed  towards  the  right  side  of  the  vertebral  column,  and,  therefore,  nearer  the  right 
than  the  left  kidney :  they  also  run  more  obliquely  on  the  right  side,  on  account  of  the 
right  kidney  being  generally  situated  lower  down  than  the  left. 

These  veins  commence  in  the  substance  of  the  kidney  by  a  number  of  minute  divisions, 
which  unite  into  small,  and  then  into  larger  branches,  gain  the  surface  of  the  organ,  and 
are  collected  into  a  single  trunk,  either  in  the  hilus  or  at  some  distance  from  it.  The 
trunk  of  each  renal  vein  is  always  placed  in  front  of  the  corresponding  artery.  The  left 
renal  vein  passes  in  front  of  the  aorta.  We  sometimes  find  one  division  of  the  left  renal 
vein  in  front  of  the  aorta,  and  another  behind  it. 

Plurality  of  the  renal  vein  appears  to  me  less  common  than  an  excess  in  the  number 
of  the  arteries. 

The  renal  veins  receive  the  inferior  supra-renal  and  several  veins  from  the  surrounding 


598  ANGEIOLOGY. 

adipose  tissue.    The  left  renal  vein  is  almost  always  joined  by  the  spermatic  or  ovarian 
vein  of  that  side. 

In  some  cases  we  find  several  communicating  branches  between  the  left  renal  vein 
and  the  superior  mesenteric,  which  is  one  of  the  branches  of  the  portal  system. 

The  Middle  Supra-renal  Veins. 
The  middle  supra-renal  or  capsular  veins,  which  are  often  numerous  and  very  large,  are 
found  on  the  surface  of  the  supra-renal  capsules,  while  the  arteries  enter  into  their  sub- 
stance from  every  point.  The  venous  trunks  run  in  the  grooves  seen  upon  the  surface 
of  the  organ.  The  left  middle  supra-renal  vein  almost  always  enters  the  renal  vein  of 
the  same  side  ;  the  right  vein  generally  opens  into  the  vena  cava  inferior. 

The  Spermatic  or  Ovarian  Veins. 

The  spermatic  veins  commence  in  the  interior  of  the  testicle,  where  they  form  a  great 
number  of  those  filaments  which  traverse  the  proper  substance  of  the  gland  :  they  aU 
terminate  in  branches,  which  are  applied  to  the  inner  surface  of  the  tunica  albuginea,  and 
are  bound  down  to  it  by  a  thin  layer  of  fibrous  tissue,  a  disposition  somewhat  resembling 
that  of  the  sinuses  of  the  dura  mater.  The  spermatic  veins  perforate  the  tunica  albu- 
ginea on  the  inner  side  of  the  epididymis,  not  opposite  that  body.  They  are  soon  joined 
by  the  veins  of  the  epididymis,  so  as  to  form  a  plexus,  which  communicates  with  the  dor- 
sal veins  of  the  penis,  and  with  the  external  and  internal  pudic  veins.  The  spermatic 
veins  soon  unite  into  five  or  six  trunks,  which  pass  upward  in  front  of  the  vas  deferens, 
and,  together  with  that  caneil  and  the  spermatic  artery,  enter  into  the  formation  of  the 
spermatic  cord.  These  veins  are  tortuous  ;  they  divide,  and  anastomose  so  as  to  form 
the  spermatic  venous  plexus,  which  is  often  tlie  seat  of  varicose  dilatations.  The  veins 
ascend  through  the  inguinal  ring  and  canal,  and  having  reached  the  interior  of  the  pel- 
vis, they  leave  the  vas  deferens,  accompany  the  corresponding  spermatic  artery  along 
the  psoas  muscle,  and  terminate  either  in  the  renal  vein,  or  in  the  inferior  vena  cava  of 
their  own  side. 

In  some  cases  the  right  spermatic  vein  opens  both  into  the  renal  vein  and  the  inferior 
cava.  When  there  are  two  veins  on  one  side,  they  communicate  with  each  other  by  a 
great  number  of  transverse  branches,  and,  before  terminating,  unite  into  a  single  trunk. 

The  name  plexus  pampiniformis  is  given  to  a  plexus  generally  formed  by  the  spermatic 
veins  before  their  termination :  this  plexus  is  more  frequently  found  on  the  left  than  on 
the  right  side,  according  to  the  observations  of  Meckel. 

The  spermatic  veins  sometimes  communicate  with  some  branches  of  the  portal  system. 

The  left  spermatic  vein  passes  under  the  sigmoid  flexure  of  the  colon,  which  may  per- 
haps account  for  the  greater  frequency  of  varicocele  on  the  left  side. 

The  ovarian  veins  accompany  the  arteries  of  the  same  name  :  they  commence  by  sev- 
eral sets  of  branches,  viz.,  uterine  branches,  which  communicate  very  freely  with  the 
uterine  sinuses  ;  ovarian  branches,  properly  so  called ;  branches  from  the  round  ligaments ; 
and,  lastly,  some  from  the  Fallopian  tubes.  All  these  unite  within  the  substance  of  the 
broad  ligaments,  and  pass  vertically  upward,  without  being  at  all  tortuous  :  in  some  ca- 
ses they  form  a  plexus  pampiniformis. 

The  ovarian  veins,  like  the  uterine  veins,  become  much  enlarged  during  pregnancy. 

The  Inferior  Phrenic  Veins. 

These  exactly  follow  the  course  of  the  inferior  phrenic  arteries,  to  each  of  which  there 
are  two  veins. 

The  hepatic  veins  do  not  in  any  way  correspond  to  the  artery  of  that  name  ;  they  form 
a  separate  system,  or,  rather,  they  are  connected  with  the  portal  venous  system,  of  which 
they  may  be  regarded  as  an  appendage. 

The  Poktal  Ststem  of  Veins. 

The  system  of  the  vena  porta  {vena  portarum),  or  the  portal  system,  constitutes  a  spe- 
cial venous  apparatus,  appended  to  the  general  venous  system,  and  representing  by  it- 
self a  complete  circulatory  tree,  having  its  roots,  trunk,  and  branches.  The  first,  or  ve- 
nous portion  of  this  system  of  veins,  is  arranged  like  the  veins  of  the  other  parts  of  the 
body,  and  has  its  roots  of  origin  in  the  spleen  and  pancreas,  and  in  the  sub-diaphragmatic 
portion  of  the  alimentary  canal ;  while  the  second,  or  arterial  portion,  sends  its  branches, 
like  those  of  an  artery,  into  the  interior  of  the  liver. 

The  hepatic  veins,  which  perform  the  functions  of  ordinary  veins  in  reference  to  the 
second  or  arterial  portion  of  the  vena  portae,  connect  the  system  of  the  vena  portae  with 
the  general  venous  system. 

The  Branches  of  Origin  of  the  Vena  PortcB. 

The  branches  of  origin  of  the  vena  portae  {i,  fig.  222)  consist  of  all  the  veins  which 
return  the  blood  from  the  sub-diaphragmatic  portion  of  the  alimentary  canal,  and  also 
from  the  spleen  and  pancreas.     They  correspond  to  the  branches  of  the  coeliac  axis, 


THE    VENA    PORTiE. 


M9 


with  the  exception  of  the  hepatic  artery ;  they  unite  FigL  a». ' 

into  three  trunks,  the  great  mesenteric  (a),  small  mes- 
enteric (b),  and  splenic  (c)  veins. 

These  veins  are  arranged  like  venae  coraites  to 
the  corresponding  arteries. 

The  Great  and  Small  Mesenteric  Veins. — The  intes- 
tinal or  mesenteric  veins  commence  just  as  the  ar- 
teries terminate,  by  two  layers  of  vessels,  viz.,  a 
sub-serous  layer,  the  vessels  of  which  ramify  be- 
neath the  peritoneum,  and  a  deep  layer,  formed  by 
the  vessels  of  the  coats  of  the  intestinal  canal.  These 
small  vessels  unite  into  anastomotic  meshes,  which 
always  lie  subjacent  to  the  arterial  network,  and 
which  terminate  in  larger  branches,  and  thus  con- 
stitute a  series  of  veins  corresponding  to  the  arter- 
ies of  the  intestine.  The  right  colic  veins  {d  d)  and 
the  veins  of  the  small  intestine  (shown  cut  short  at 
e)  terminate,  the  one  in  the  right  and  the  other  in 
the  left  side  of  the  superior  mesenteric  or  great  mes- 
araic  vein  (a) :  this  vein,  in  the  early  periods  of  in- 
tra-uterine  life,  receives  the  omphalo-mesenteric  vein, 
a  branch  which  corresponds  to  the  omphalo-mesen- 
teric artery,  and  commences  upon  the  vesicula  um-  i 
bilicalis  ;  the  artery  and  the  vein  disappear  about 
the  third  month  of  utero-gestation,  but  the  vesicle  remains  for  a  longer  period.  On  the 
other  hand,  the  left  colic  veins  (/)  enter  the  inferior  mesenteric  or  small  mesaraic  vein  (J) : 
this  vessel  forms  the  continuation  of  the  superior  hemorrhoidal  veins  {g),  which  commu- 
nicate very  freely  with  the  middle  and  inferior  hemorrhoidal  branches  of  the  internal 
iliac  vein. 

The  splenic  vein  (c),  which  is  proportionally  larger  than  the  artery,  arises  in  the  cells 
of  the  spleen  by  a  great  number  of  roots,  which  gradually  unite  in  the  hilus  of  that  organ, 
and  form  the  same  number  of  branches  as  there  are  arteries,  each  coming  from  a  dis- 
tinct compartment  of  the  organ.  All  these  branches  soon  unite  into  a  single  trunk, 
which  passes  across  to  the  right  side  behind  the  pancreas,  and,  therefore,  behind  the 
splenic  artery,  which  it  accompanies  without  being  tortuous  :  it  is  one  of  the  branches 
immediately  concerned  in  forming  the  trunk  of  the  vena  portae.  During  its  course,  the 
splenic  vein  receives  the  venous  vasa  brevia  {h  h)  from  the  stomach. 

The  inferior  mesenteric  vein  opens  into  the  splenic  ;  so  that  there  are  only  two  venous 
trunks,  the  union  of  which  constitutes  the  vena  portae,  viz.,  the  splenic  and  the  great  or 
superior  mesenteric. 

The  Vena  Portce. 

The  trunk  of  the  vena  porta  (i)  is  formed  by  the  union  of  the  splenic  and  superior  mes- 
enteric veins  at  an  acute  angle,  behind  the  right  extremity  of  the  pancreas,  in  front  of  the 
Tertebral  column,  and  to  the  left  of  the  vena  cava  inferior.  The  vena  portae  is  larger 
than  either  of  its  two  branches  of  origin,  but  is  smaller  than  the  two  taken  together.  It 
passes  obliquely  upward  and  to  the  right  side  ;  and,  after  running  for  about  four  inches, 
reaches  the  left  extremity  of  the  transverse  fissure  of  the  liver,  where  it  terminates  by 
bifurcating.  The  following  are  its  relations  during  its  course  :  anteriorly  it  is  covered 
by  the  head  of  the  pancreas,  the  second  portion  of  the  duodenum,  the  hepatic  artery,  the 
biliary  ducts,  and  the  lymphatics  of  the  liver,  and  also  by  some  branches  from  the  hepatic 
plexus  of  nerves ;  posteriorly  it  is  covered  by  that  portion  of  peritoneum  which  dips  be- 
hind the  vessels  of  the  liver  into  the  foramen  of  Winslow,  to  line  the  sac  of  the  great 
omentum.  By  this  foramen  it  is  separated  from  the  inferior  vena  cava,  the  direction  of 
which  it  crosses  at  a  very  acute  angle. 

The  two  branches  into  which  the  vena  porta?  divides  in  the  transverse  fissure  of  the 
liver  separate  so  widely  from  each  other,  that  they  seem  to  form  a  trunk,  at  right  angles 
to  which  the  vena  portae  itself  is  attached.  Some  anatomists  apply  the  term  sinus  of  the 
vena  porta  to  that  portion  of  the  vein  which  is  situated  in  the  transverse  fissure  ;  that  part 
of  the  vein  which  adheres  to  the  liver  is  more  commonly  called  the  hepatic  portion  of  the 
vena  portae,  to  distinguish  it  from  the  free  and  floating  part,  which  is  named  the  abdom- 
inal portion. 

The  two  divisions  of  the  vena  portae  pass  horizontally  each  towards  the  correspond- 
ing lobe  of  the  hver ;  they  soon  divide  and  subdivide  into  diverging  branches,  which  sup- 
ply all  the  granules  or  lobules  of  the  liver.  The  branches  of  the  vena  portae  are  accom- 
panied by  the  ramifications  of  the  hepatic  artery  and  biliary  ducts.  The  capsule  of  Glis- 
son,  or  the  fibrous  coat  of  the  liver,  is  reflected  upon  them,  and  forms  a  common  sheath 
for  them.     (See  Liver.) 

Before  birth,  the  hepatic  portion  {p,  fig.  164)  of  the  vena  portae  receives,  besides  the 


v|690  ANGEIOLOGY. 

abdominal  portion  of  the  same  vein,  the  umbilical  vein  (u),  which  is  obliterated  soon  after 
birth.     Nevertheless,  I  once  found  it  perfectly  permeable  in  an  adult.* 

Before  birth  the  ductus  venosus  (d)  extends  from  the  hepatic  portion  of  the  portal  vein 
to  the  vena  cava  inferior,  between  which  and  the  vena  portae  it  establishes  a  direct  com- 
munication. This  hepatic  portion  might>  therefore,  be  named  the  confluence  of  the  veins 
of  the  liver. 

The  Hepatic  Veins. 

The  capillary  radicles  of  the  hepatic  or  supra-hepatic  veins  commence  in  the  capillary 
divisions  of  the  vena  portae,  and,  gradually  uniting  into  larger  and  larger  branches,  con- 
verge towards  the  posterior  border  of  the  liver,  or,  rather,  towards  the  fissure  for  the 
vena  cava  inferior,  at  which  point  they  terminate  by  an  indefinite  number  of  small 
branches,  named  the  small  hepatic  veins,  which  open  all  along  the  fissure  ;  and  also  by  two 
principal  trunks,  the  great  hepatic  veins,  which  end  in  the  vena  cava  immediately  before 
It  passes  into  the  opening  in  the  diaphragm.  One  of  these  great  hepatic  veins  comes  from 
the  right  lobe,  and  the  other  from  the  left  lobe  of  the  liver. 

The  vein  of  the  left  side  often  receives  a  great  number  of  branches  from  the  right  lobe 
of  the  liver,  and  is  larger  than  the  vein  of  the  right  side. 

The  vena  cava  inferior  is  always  dilated  into  a  large  ampulla  opposite  the  openings  of 
the  hepatic  veins. 

It  follows,  from  the  previous  description,  that,  in  the  liver,  the  branches  of  the  hepatic 
veins  and  those  of  the  vena  portae  run  directly  across  each  other,  since  the  latter  diverge 
from  the  centre  of  the  organ  towards  its  right  and  left  extremities,  while  the  former  con- 
verge from  the  anterior  towards  the  posterior  border. 

Moreover,  the  branches  of  the  hepatic  veins  are  unaccompanied  by  other  vessels,  and 
are  in  direct  contact  with  the  tissue  of  the  liver ;  while  those  of  the  vena  porta;  are  sep- 
arated from  it  by  the  capsule  of  Glisson,  and  are  accompanied  by  the  ramifications  of  the 
artery,  the  nerves,  and  the  hepatic  ducts. 

I  shall  farther  remark,  that  although  the  hepatic  veins  gradually  unite,  like  other  veins, 
into  branches,  which  decrease  in  number,  but  increase  in  size,  they  most  of  them  receive 
besides,  during  their  course,  a  multitude  of  capillary  vessels,  the  inter-lobular  hepatic 
veins,  from  the  neighbouring  lobules  ;  so  that  their  internal  surface  is  perforated  with  in- 
numerable foramina. 

The  cribriform  structure  of  their  internal  surface  is  therefore  a  peculiar  characteristic 
of  all  the  hepatic  veins  [except  the  very  large  ones],  and  enables  us  always  to  distinguish 
them  from  the  branches  of  the  vena  portae. 

Lastly,  the  capillary  communication  between  the  extremities  of  the  vena  portse  and 
hepatic  veins  is  extremely  free,  as  may  be  shown  even  by  very  coarse  injections. 

AH  the  veins  of  the  portal  system  are  without  valves,t  and  they  can  therefore  be  in- 
jected with  the  greatest  ease  from  the  trunks  towards  the  extremities.  An  injection 
thrown  in  towards  the  intestine  penetrates  very  readily  into  the  interior  of  the  alimentary 
canal,  so  that  the  minute  branches  of  the  vena  portae  appear  to  open  at  the  apex  of  each 
villus.  This  can  be  made  evident  by  throwing  mercury  into  the  vena  portae,  and  then 
forcing  it  on  by  an  ordinary  injection ;  drops  of  the  mercury  will  then  be  seen  in  the 
open  mouth  of  each  villus.J 

The  system  of  the  vena  portas  is  not  so  completely  isolated  from  the  general  venous 
system  as  is  commonly  stated.  It  always  communicates  with  branches  of  the  iirtemal 
iliac  veins  by  means  of  the  middle  hemorrhoidal  veins,  and  communicating  branches 
with  the  renal  veins  have  also  been  noticed  ;  and  hence  injections  of  the  vena  cava  in- 
ferior always  enter  in  a  greater  or  less  degree  into  the  veins  of  the  portal  system. 

The  Common  Iliac  Veins. 

The  common  iliac  veins  (n  n,  fig.  222)  correspond  exactly  to  the  arteries  of  the  same 
name  ;  they  commence  opposite  the  sacro-vertebral  articulation  by  the  junction  of  the 
internal  and  external  iliac  veins,  and  terminate  by  uniting  at  an  acute  angle  to  form  the 
vena  cava  inferior  or  ascendens,  the  point  of  union  being  opposite  the  articulation  of  the 
fourth  and  fifth  lumbar  vertebrae,  to  the  right  side  of,  and  a  little  below,  the  bifurcation 
of  the  aorta. 

The  common  iliac  veins  hare  the  same  relation  to  the  lower  extremities  that  the 
brachio-cephalic  veins  bear  to  the  upper ;  and  as  the  right  brachio-cephalic  vein  is  shorter 
and  more  vertical  than  the  left,  so  also  is  the  right  common  iliac  vein  shorter  and  mere 
vertical  than  the  left. 

The  relations  of  the  common  iliac  veins  with  the  corresponding  arteries  are  remarkable, 
inasmuch  as  they  are  placed  between  these  vessels  and  the  vertebral  column.  The 
right  common  iliac  vein  is  situated  to  the  outer  side  of  and  behind  the  corresponding  ar- 

*  Anat.  Pathol.,  livraison  17. 

t  M.  Bauer  says  that  he  has  seen  valves  in  the  venous  vasa  brevia  of  the  stomach  ;  I  have  never  been  able 
to  discover  them. 

t  [The  escape  of  the  mercury  is  due  to  rupture  of  the  bloodvessels.  In  tlie  villi,  the  minute  branches  of 
the  vena  portae  commence  la  t!',t  ciijiillary  network  described  and  figured  at  page  36!).] 


THE  INTERNAL    ILIAC  VEIN,  ETC.  %9i 

leiy,  and  is  parallel  to  it ;  while  the  left  common  iliac  is  situated  on  the  inner  side,  and 
behind  the  corresponding  artery,  and  is  covered  by  its  lower  part.  At  the  point  where 
the  left  common  iliac  vein  joins  the  vena  cava  inferior,  it  is  also  crossed  obliquely  by  ihe 
right  common  iliac  artery.  It  follows,  therefore,  that  the  left  common  illiac  vein  is 
covered,  and  may  be  compressed  by  both  common  iliac  arteries,  while  the  right  common 
iliac  vein  cannot  be  compressed  by  either  of  them,  and  probably  this  is  partly  the  reason 
why  anasarca  of  the  left  lower  extremity  is  more  common  than  in  the  right  extremity 
m  atonic  diseases. 

The  right  common  iliac  vein  receives  no  collateral  branch ;  the  left  common  iliac  (n, 
fig.  223)  is  joined  by  the  middle  sacral  vein  (h). 

The  middle  sacrai  vein  is  situated  in  the  median  line,  and  its  size  depends  upon  that  of 
the  artery  of  the  same  name  ;  it  belongs  to  the  rachidian  veins,  with  which  it  will  be 
described 

The  Internal  Iliac  Vein. 

The  internal  iliac  or  hypogastric  vein  exactly  represents  the  internal  iliac  artery,  on  the 
inner  side  of  which  it  is  situated,  separated  from  it,  however,  by  a  very  thin  fibrous 
layer,  which  holds  it  down  against  the  walls  of  the  pelvis. 

The  internal  iliac  vein  receives  the  venae  comites  of  the  branches  of  the  internal  iliac 
artery,  the  umbilical  arteries  in  the  foetus  alone  being  excepted ;  for  their  satellite  vein, 
the  umbihcal  vein,  which  is  £dso  peculiar  to  the  foetus,  terminates  in  the  hepatic  portion 
of  the  vena  portae,  as  we  have  already  seen. 

The  internal  iliac  vein,  therefore,  receives  the  blood  returned  from  the  parietes  of  the 
pelvis,  from  the  organs  contained  within  the  cavity  of  the  pelvis,  and  from  the  external 
genitals.  There  are  always  two  veins  for  each  artery  ;  but  the  two  unite  into  a  single 
vein  at  their  point  of  termination  in  the  principal  trunk. 

The  veins  belonging  to  the  parietes  of  the  pelvis,  viz.,  the  gluteal,  obturator,  and  sciatic 
veins,  are  arranged  precisely  like  the  corresponding  arteries.  The  ilio-lumbar  and  lateral 
sacral  veins  {i,fig.  223)  form  part  of  the  rachidian  system,  which  will  be  specially  described. 

The  veins  belonging  to  the  genito-urinary  organs  present  a  plexiform  arrangement 
both  in  their  trunks  and  in  their  roots,  which  deserves  particular  attention. 

Some  of  the  venous  plexuses  of  the  pelvis  are  found  both  in  the  male  and  female,  as 
the  hemorrhoidal,  while  some  are  peculiar  to  one  or  the  other  sex,  as  the  vesico-prostatic 
and  the  plexuses  of  the  penis  to  the  male,  and  the  vaginal  and  uterine  plexuses  to  the 
female. 

The  Hemorrhoidal  Veins  and  Plexuses. 
The  hemorrhoidal  veins  and  plexus  form  a  venous  network,  surrounding  the  lower  end 
of  the  rectum.  They  are  formed  by  the  superior  hemorrhoidal  veins,  which  form  the  com- 
mencement of  the  inferior  mesenteric,  and  by  the  middle  and  inferior  hemorrhoidal  veins, 
which  are  branches  of  the  internal  iUac.  We  ought  to  notice  in  particular  the  sub-mu- 
cous venous  network  near  the  anus.  The  plexus  formed  by  it  is  analogous  to  that  found 
in  all  other  mucous  membranes ;  its  vessels  are  liable  to  become  varicose,  a  condition 
which  constitutes  the  greater  number  of  hemorrhoidal  tumours. 

The  Pelvic  Veins  and  Plexuses  in  the  Male. 

Preparation. — Introduce  one  injection-pipe  into  the  corpus  cavernosum,  and  another  into 
the  glans  penis,  and  then  push  an  injection  simultaneously  into  both  of  them,  and  also 
into  the  crural  vein. 

The  superficial  scrotal  veins  tenninate  partly  in  the  superficial  veins  of  the  perinseum, 
and  partly  in  the  external  pudic  branches  of  the  femoral  vein ;  they  communicate  with 
the  superficial  veins  of  the  under  surface  of  the  penis. 

The  Vesical  Veins,  or  Vesico-prostatic  Plexus. — The  prostate  gland  and  the  neck  ol  the 
bladder  are  covered  by  a  very  complicated  plexus  of  veins,  which  become  exceedingly 
developed  in  chronic  inflammation  of  the  bladder ;  it  receives  the  superficial  veins  of  the 
penis,  and  gives  off  the  vesical  veins. 

This  plexus,  which  communicates  with  the  hemorrhoidal  plexus  behind,  is  supported 
by  a  very  thick  fibrous  layer,  which  is  continuous  with  the  pelvic  fascia,  and  which  lim- 
its the  degree  of  dilatation  of  the  veins  of  the  plexus  in  the  same  way  as  the  dura  mater 
limits  the  dilatation  of  the  sinuses  contained  between  its  layers. 

The  Veins  and  Plexuses  of  the  Penis. — The  veins  of  the  penis  are  divided  into  a  superfir 
cial  and  deep  set,  the  former  representing  the  sub-cutaneous  veins  of  the  limbs.  They 
commence  in  the  skin  of  the  prepuce,  and  run  backward  along  the  upper  and  lower  sur- 
faces of  that  organ.  The  superior  are  called  the  dorsal  veins  of  the  penis ;  they  commu- 
nicate freely  with  each  other  by  large  branches  ;  most  of  them  run  beneath  the  arch  of 
the  pubes,  between  it  and  the  corpus  cavernosum,  passing  through  some  openings  or 
fibrous  canals  in  the  sub-pudic  ligament,  which  have  the  effect  of  keeping  the  veins  al- 
ways open ;  they  end  by  assisting  in  the  formation  of  the  prostatic  plexus.  These  veins 
communicate  freely  with  the  deep  veins,  especially  opposite  the  junction  of  the  two  crura 

4  G 


602  ANGEIOLOGY. 

of  tHfe  corpus  cavemosum :  this  communication  is  proved  by  the  fact  that  the  superficial 
vessels  are  always  filled  when  the  injection  is  thrown  into  the  deep  veins. 

The  areolar  tissue  of  the  corpus  cavemosum  and  that  of  the  corpus  spongiosum  may 
be  regarded  as  composed  of  a  venous  network  or  plexus  at  its  maximum  of  development. 
Branches  proceed  from  this  plexus,  which  correspond  to  the  divisions  of  the  internal 
pudic  artery,  and  follow  the  same  course. 

These  veins,  and  the  vesico-prostatic  plexuses,  are  liable  to  become  varicose ;  hard 
earthy  concretions,  called  phlebolites,  are  also  frequently  found  in  them. 

The  Pelvic  Veins  and  Plexuses  in  the  Female. 

The  vesical,  or  vesico-urethral  plexus  of  the  female,  is  less  developed  than  that  of  the 
male,  on  account  of  the  absence  of  veins  corresponding  to  the  superficial  veins  of  the  pe- 
nis, which  are  represented  by  a  few  branches  from  the  labia  majora.  This  plexus  commu- 
nicates with  the  veins  of  the  clitoris,  and  also  very  freely  with  the  vaginal  plexus  behind 

The  vaginal  plexus  is  a  vascular  network,  extremely  well  developed,  especially  oppo- 
site the  orifice  of  the  vulva,  which  is  entirely  surrounded  by  it  with  several  series  of  cir 
cular  anastomosing  veins  :  it  communicates  with  the  vesical  plexus  in  front,  and  with 
the  hemorrhoidal  plexus  behind ;  so  that  all  the  plexuses  in  the  pelvis  are  involved  in 
the  state  of  turgescence,  which  a.ccompanies  the  phenomenon  of  erection  in  the  female. 
The  radicles  of  this  vaginal  plexus  commence  in  the  mucous  membrane  of  the  vagina, 
and  especially  in  the  erectile  tissue  surrounding  the  orifice  of  that  canal ;  some  large 
veins  arise,  in  particular,  from  the  bulb  of  the  vagina,  forming  a  true  erectile  apparatus, 
which  we  have  already  described.     (See  Splanchnology,  p.  320.) 

The  Uterine  Plexus. — The  veins  contained  in  the  substance  of  the  walls  of  the  uterus 
do  not  present  any  trace  of  the  tortuous  arrangement  of  the  corresponding  arteries.  In 
order  to  obtain  a  satisfactory  idea  of  them,  they  should  be  studied  in  a  gravid  uterus. 
The  uterine  veins,  like  the  uterine  arteries,  are  then  found  along  the  sides  and  upper  an- 
gles of  the  organ  ;  opening  into  these  veins  are  found  larger  venous  canals,  which  run  from 
side  to  side  through  the  substance  of  the  uterus,  and  anastomose  frequently  with  each 
other.  These  venous  canals  are  called  the  uterine  sinuses,  on  account  of  their  great 
size  during  gestation,  and  from  the  dilatations  presented  by  them  at  the  confluence  of  sev- 
eral secondary  veins  :  they  are  also  entitled  to  be  so  named  from  their  structure,  which 
has  some  analogy  with  that  of  the  sinuses  of  the  dura  mater,  inasmuch  as  only  the  lining 
membrane  of  the  veins  is  prolonged  into  them  ;  their  outer  coat  is  formed  by  the  proper 
tissue  of  the  uterus,  and  hence  the  walls  of  these  veins  are  contractile.  I  have  stated 
elsewhere  that,  in  reference  to  its  veins,  we  may  consider  the  uterus  as  consisting  of  an 
erectile  tissue  with  muscular  walls  ;  it  is  scarcely  necessary  to  add,  that  these  sinuses 
are  unequally  developed  in  different  parts  of  the  uterus,  and  that  the  point  to  which  the 
placenta  has  been  attached  may  be  recognised  by  the  greater  size  of  the  adjacent  ute- 
rine sinuses. 

The  veins  contained  within  the  substance  of  the  walls  of  the  uterus  do  not  open  into 
the  uterine  veins  alone ;  several  of  them  terminate  in  the  ovarian  veins,  which  commu- 
nicate freely  with  the  uterine,  and  may,  if  necessary,  supply  their  place. 

The  great  size  acquired  by  the  uterine  veins,  both  in  the  substance  and  on  the  surface 
of  the  uterus,  proves  that  the  venous  apparatus  plays  an  important  part  in  the  intersti- 
tial development  of  this  organ. 

Moreover,  the  size  of  the  veins  and  venous  plexuses  belonging  to  all  the  genito-urinary 
organs,  and  the  essentially  venous  structure  of  such  organs  as  are  capable  of  being  erect- 
ed, prove  that  the  venous  system  performs  an  essential  part  in  the  truly  active  phenom- 
ena of  erection.  It  is  partly  upon  these  anatomical  and  physiological  arguments  that  I 
have  endeavoured  to  show  the  active  part  performed  by  the  veins  in  all  the  great  phe- 
nomena of  the  economy,  such  as  nutrition,  secretion,  inflammation,  &c. 

The  pelvic  veins  are  provided  with  a  great  number  of  valves,  which  prevent  injections 
from  passing  from  the  heart  towards  their  extremities  ;  it  ought  to  be  remembered,  that 
the  venous  plexuses  of  the  pelvis  establish  a  very  important  and  verv  free  communica- 
tion between  the  veins  of  the  right  and  left  sides  of  the  body. 

The  Deep  Veins  of  the  Lower  Extremity. 
The  veins  of  the  lower  extremities,  like  those  of  the  upper,  are  divided  into  the  deep 
veins  or  venae  comites  of  the  arteries,  and  the  superficial  veins. 

The  Plantar,  Posterior  Tibial,  Peroneal,  Dorsal,  interior  Tibial,  and  Pop 

liteal  Veins. 
The  external  and  internal  plantar  veins  unite  to  form  the  posterior  tibial,  which  accom- 
panies the  artery  of  that  name,  and  soon  joins  the  peroneal  vein,  to  constitute  the  tibio- 
peroneal  vein :  again,  the  anterior  tibial  vein,  which  commences  by  the  vena  dorsalis  pedis, 
perforates  the  upper  part  of  the  interosseous  ligament,  joins  the  tibio-peroneal  vein,  and 
in  this  way  forms  the  popliteal  vein  Up  to  this  point  there  are  two  venae  comites  for 
each  artery,  one  of  the  veins  being  placed  on  each  side  of  the  artery,  across  which  thev 


THE    FEMORAL    VEIN,    ETC.  608 

very  frequently  send  communicating  branches.  The  peroneal  veins  are  generally  larger 
than  the  posterior  tibial,  and  receive  all  the  muscular  veins  from  the  posterior  and  out«»- 
tegions  of  the  leg. 

Commencing  with  the  popliteal,  there  is  only  one  vein  for  the  main  artery  of  the 
limb  ;  but  the  arteries  of  the  second  and  third  order  always  have  two  veins. 

The  popliteal  vein  is  situated  in  the  popliteal  space,  behind  and  in  contact  with  the  ar- 
tery. Its  coats  are  remarkably  thick,  so  that  when  cut  across  it  remains  open,  and  in 
the  dead  body  has  been  sometimes  mistaken  for  the  artery.  Below,  and  opposite  the 
articulation  of  the  knee,  the  vein  is  situated  immediately  behind  the  artery ;  above  the 
joint  it  is  behind,  and  a  little  to  the  outer  side. 

The  popUteal  vein  receives  the  large  bundles  of  veins,  the  sural  veins,  from  the  gas 
trocnemius  muscle  :  they  are  remarkable  ft)r  the  number  of  their  valves ;  also  the  articu- 
lar veins,  and  generally  the  external  saphenous  vein.  I  have  seen  a  small  vein  having 
very  numerous  valves,  and  being  analogous  to  the  collateral  venous  canals  of  which  I 
have  already  spoken,  extend  from  the  upper  part  of  the  anterior  tibial  to  the  middle  of 
the  popliteal  vein. 

The  Femoral  Vein. 

The  femoral  vein,  like  the  artery  of  that  name,  is  bounded  below  by  the  ring  in  the 
tendon  of  the  adductor  magnus,  and  above  by  the  crural  arch ;  it  has  different  relations 
with  the  femoral  artery  in  various  parts  of  its  course  :  thus,  below,  it  is  on  the  outer 
side  of  the  artery ;  higher  up,  it  is  situated  behind  that  vessel ;  lastly,  from  the  entrance 
of  the  vena  saphena  interna  to  the  crural  arch,  it  is  placed  to  the  inner  side  of  the  artery, 
and  is  in  close  contact  with  the  posterior  part  of  the  opening  for  the  femoral  vessels  ;  so 
that  femoral  hemiae  descend  in  front  of  the  vein,  but  not  of  the  artery.  The  femoral  vein 
is  single,  like  the  artery  ;  nevertheless,  there  are  one  or  two  collateral  venous  canals, 
which  run  parallel  with  the  lower  half,  or  lower  two  thirds  of  that  vein ;  some  commu- 
nicating branches  from  the  internal  saphenous  vein,  and  some  muscular  branches,  open 
into  these  venous  cauEds,  which  are  always  abundantly  supplied  with  valves. 

The  femoral  vein  receives  all  the  branches  corresponding  to  the  divisions  of  the  fem 
oral  artery,  excepting  the  external  pudic  veins  and  the  cutaneous  veins  of  the  abdomen, 
which  terminate  in  the  internal  saphenous  vein. 

The  great  deep  vein  (profunda)  opens  into  the  femoral  about  ten  or  twelve  lines  be- 
low the  crural  arch. 

The  External  Iliac  Vein. 

The  external  iliac  vein  is  bounded  below  by  the  femoral  arch,  and  terminates  at  the  up- 
per part  of  the  sacro-iliac  symphysis  by  uniting  with  the  internal  iliac  vein ;  it  has  the 
same  relations  as  the  artery,  and  is  placed  behind  and  to  the  inner  side  of  that  vessel, 
excepting  over  the  os  pubis,  where  it  is  exactly  to  the  inner  side  of  the  artery.  In  one 
case  I  found  the  left  common  iliac  receiving  the  right  internal  iliac,  so  that  the  right  ex- 
ternal iliac  was  prolonged  into  the  vena  cava. 

The  external  iliac  receives  the  epigastric  and  the  circumflex  iliac  veins.  These  two 
veins  are  double,  but  each  pair  unites  into  a  single  trunk,  as  it  is  on  the  point  of  open- 
ing into  the  external  iliac  vein. 

All  the  deep  veins  of  the  lower  extremity,  excepting  the  external  iliac,  are  provided 
with  valves.  There  are  four  in  the  deep  femoral,  the  same  number  in  the  popliteal,  and 
many  more  in  the  tibial  and  peroneal  veins ;  the  mouths  of  all  the  small  veins  which 
open  into  them  are  provided  with  a  pair  of  valves. 

The  Superficial  Veins  of  the  Lower  Extremity. 

The  superficial  veins  of  the  lower  extremity  are  much  less  numerous  than  those  of 
the  upper,  and  all  terminate  in  two  trunks,  viz.,  the  internal  saphenous  vein  and  the  exter- 
nal saphenous  vein. 

As  in  the  hand,  they  are  all  situated  upon  the  dorsal  region  of  the  foot.  All  the  col- 
lateral veins  of  the  toes  enter  the  convexity  of  a  venous  arch,  which  is  more  regular  and 
constant  than  that  in  the  hand,  and  which  is  placed  on  the  fore  part  of  the  metatarsus. 
From  the  inner  end  of  this  arch  is  given  off  a  large  branch,  named  the  internal  dorsal 
veir  of  the  foot,  which  is  the  origin  of  the  internal  saphenous  vein  ;  the  outer  extremity 
also  gives  off  a  somewhat  smaller  branch,  called  the  external  dorsal  vein  of  the  foot,  which 
forms  the  commencement  of  the  external  saphenous  vein. 

The  Internal  Saphenous  Vein. 
The  internal  or  great  saphenous  vein  (saphena  interna,  s,  in  the  representation  of  the 
superficial  nerves  of  the  leg)  is  a  collateral  vein  gf  the  femoral  venous  trunk,  and  is  con- 
tinuous with  the  internal  dorsal  vein  of  the  foot.  The  last-mentioned  vein  commences 
at  the  inner  extremity  of  the  dorsal  venous  arch  of  the  foot,  into  which  the  collateral 
veins  of  the  great  toe  open  ;  it  runs  along  the  dorsal  surface  of  the  first  metatarsal  bone 
and  the  corresponding  part  of  the  tarsus,  and  receives,  during  its  course,  a  deep  branch 
from  the  internal  plantar  vein  and  all  the  superficial  veins  of  the  internal  olantar  region, 


604  ANGEIOLOGY. 

and  particularly  the  internal  calcaneal  vein,  which  is  sometimes  large,  and  which,  in  cer- 
tain cases,  does  not  terminate  in  the  saphenous  vein  until  it  has  reached  above  the  in- 
ternal malleolus,  around  the  posterior  border  of  which  it  turns.  The  internal  saphe- 
nous vein  succeeds  to  the  one  just  described ;  it  is  reflected  upward  in  front  of  the 
internal  malleolus,  and  continues  to  ascend  upon  the  inner  surface,  then  along  the  pos- 
terior border  of  the  tibia,  and  upon  the  back  of  the  internal  tuberosity  of  that  bone  and 
the  internal  condyle  of  the  femur.  In  this  place  it  is  situated  on  the  inner  side  of  the 
tendons  of  the  semi-tendinosus,  gracilis,  and  sartorius  ;  it  then  inclines  forward,  descri- 
bing a  slight  curve,  with  its  concavity  directed  forward ;  ascends  along  the  anterior  bor- 
der of  tfie  sartorius,  and  crosses  obliquely  over  the  adductor  longus ;  having  arrived  at 
the  saphenous  opening  in  the  fascia  lata,  about  eight  or  ten  inches  below  Poupart's  lig- 
ament, it  immediately  curves  backward,  passes  through  that  opening,  and  enters  into 
the  femoral  vein,  just  as  the  vena  azygos  enters  into  the  superior  vena  cava,  that  is  to 
say,  it  describes  a  loop  having  its  convexity  directed  downward.  Several  lymphatic 
glands  are  found  near  this  curve. 

Relations. — The  internal  saphenous  vein  is  separated  from  the  skin  by  a  very  thin 
fibrous  layer,  the  superficial  fascia,  and  is  in  relation  with  the  internal  malleolus,  the 
tibia,  the  tibial  origin  of  the  soleus,  the  tendons  of  the  semi-tendinosus,  gracilis,  and  sar- 
torius, with  the  last-named  muscle  itself,  and  with  the  adductor  longus.  It  is  accompa- 
nied by  the  internal  saphenous  nerve,  from  the  knee  down  to  the  internal  malleolus. 

During  its  course  it  receives  all  the  sub-cutaneous  veins  of  the  thigh,  most  of  the  sub- 
cutaneous veins  of  the  leg,  the  sub-cutaneous  veins  of  the  abdomen,  the  external  pudic 
veins,  and  several  communicating  branches  from  the  deep  veins. 

The  sub-cutaneous  femoral  veins  of  the  back  of  the  thigh  sometimes  unite  into  one  rath- 
er large  trunk,  which  appears  like  a  second  internal  saphenous  vein  ;  it  runs  parallel  with 
the  regular  vein,  and  enters  it  at  a  greater  or  less  distance  from  its  termination.  I  have 
met  with  an  anterior  superficial  vein  which  commenced  around  the  patella,  ascended 
vertically  along  the  anterior  region  of  the  thigh,  and  might  be  regarded  as  a  third.saphe- 
nous  vein.  In  one  case  of  this  kind,  these  three  saphenous  veins,  viz.,  the  anterior, 
posterior,  and  internal,  entered  separately  into  the  femoral  vein,  or,  rather,  into  a  dilata- 
tion in  which  the  internal  saphenous  vein  terminated. 

The  internal  saphenous  vein  often  presents  the  following  arrangement :  opposite  the 
lower  part  of  the  leg,  or  at  the  lower  end  of  the  thigh,  it  divides  into  two  equal  branches 
which  pass  upward,  communicate  with  each  other  by  transverse  branches,  and  unite  af- 
ter running  a  variable  distance  ;  in  these  cases  the  two  branches  represent  a  very  elon- 
gated ellipse.  I  have  even  seen  this  arrangement  in  both  the  thigh  and  leg  of  the  same 
subject,  that  is  to  say,  the  saphenous  vein  divided  into  two  branches  in  the  leg,  which 
united  opposite  the  internal  tuberosity  of  the  tibia,  and  again  divided  in  the  thigh. 

It  is  not  uncommon  to  find  a  venous  network  supplying  the  place  of  the  internal  saphe- 
nous vein  in  the  thigh. 

The  sub-cutaneous  abdominal  veins  should  be  arranged  among  the  superficial  and  sup- 
plementary veins,  although  there  is  a  small  artery,  the  superficial  epigastric,  which  cor- 
responds to  them.  There  are  three  or  four  of  these  veins,  which  are  joined  by  one  from 
the  gluteal  region ;  they  open  sometimes  by  a  common  trunk,  sometimes  by  three  or 
four  distinct  trunks,  into  the  internal  saphenous,  just  as  that  vein  is  passing  through  the 
fascia  lata.  In  a  case  of  obliteration  of  the  vena  cava  I  found  these  veins  very  large, 
and  prolonged  over  the  thorax  into  the  axilla,  where  they  anastomosed  with  the  cuta- 
neous branches  of  the  intercostal  and  thoracic  veins.  In  a  case  in  which  the  umbilical 
vein  was  persistent,  the  right  and  left  internal  saphenous  veins  were  tortuous,  and  as 
large  as  the  little  finger.* 

The  internal  saphenous  also  receives  the  external  pudic  veins ;  and  I  have  seen  it  joined 
by  the  obturator  vein,  which  commenced  by  a  common  trunk  with  the  epigastric. 

The  communicating  branches  of  the  internal  saphenous  with  the  deep  veins  are  very  nu- 
merous, and  should  be  studied  in  the  foot,  the  leg,  and  the  thigh.  The  origin  of  the  in- 
ternal saphenous  vein  gives  off  a  branch,  which  communicates  with  the  internal  plan- 
tar vein. 

Along  the  leg  several  other  branches  exist,  which  establish  a  communication  between 
the  internal  saphenous  and  the  posterior  tibial  veins  ;  these  branches  perforate  the  tib- 
ial origins  of  the  soleus  muscle. 

There  is  a  very  remarkable  communication  between  the  anterior  tibial  and  internal 
saphenous  veins  in  the  middle  third  of  the  leg,  by  means  of  a  branch  which  proceeds 
from  the  anterior  tibial  vein  in  front  of  the  fibula,  becomes  sub-cutaneous,  is  reflected 
inward  and  upward  between  the  fascia  of  the  leg  and  the  skin,  and  terminates  in  the  in- 
ternal saphenous. 

Again,  an  inferior,  internal,  articular  vein  enters  the  internal  saphenous. 

Lastly,  the  anastomoses  in  the  thigh,  between  the  deep  and  the  superficial  veins,  aiu 
less  numerous  than  those  in  the  leg ;  at  most  we  only  find  two  such  describing  loops,  with 
the  concavity  directed  upward. 

*  Anat.  Path.,  liv.  xviii. 


1 


THE    VEINS    OF    THE    SPINE.  #11$ 

Valves. — The  number  of  the  valves  appears  to  me  variable  :  I  have  counted  six  along 
the  internal  saphenous,  but  at  other  times  I  have  not  found  more  than  two  or  four. 
There  is  a  greater  number  of  valves  in  this  vein  in  the  thigh  than  in  the  leg. 

The  External  or  Posterior  Saphenous  Vein. 

The  external  saphenous  vein  (la  peroneo-malleolaire,  Chauss. ;  see  figure  of  nerves  ot 
.eg),  smaller  and  much  shorter  than  the  internal  saphenous,  is  a  branch  of  the  popliteal 
vein ;  it  forms  a  continuation  of  the  external  dorsal  vein  of  the  foot,  vi'hich  commences 
from  the  outer  extremity  of  the  dorsal  venous  arch  ;  it  passes  behind  the  peroneo-tibial 
articulation,  crossing  it  from  before  backward  ;  it  receives,  as  it  runs  outward,  a  grea< 
number  of  branches,  the  chief  of  which  come  from  the  external  plantar  region  ;  also  an 
external  calcaneal  vein,  which  is  sometimes  of  considerable  size,  and  comes  from  thr 
outer  side  of  the  os  calcis ;  the  vein  then  runs  along  the  outer  border  of  the  tendo  Achil- 
lis,  and  crosses  it  at  a  very  acute  angle,  to  reach  the  middle  line  of  the  posterior  aspect 
of  the  leg :  conmiencing  at  this  point,  it  passes  directly  upward,  crosses  the  internal 
popliteal  nerve,  and  terminates  in  the  popliteal  vein  between  the  internal  and  external 
popliteal  nerves,  between  the  two  heads  of  the  gastrocnemius,  and  by  the  side  of  the  in- 
ternal inferior  articular  vein. 

In  some  subjects  the  external  saphenous,  at  the  moment  when  it  bends  to  dip  into 
the  pophteal  space,  gives  off  an  ascending  vein,  which  runs  along  the  posterior  border 
of  the  semi-membranosus  muscle,  as  high  as  the  upper  third  of  the  thigh,  where  it  then 
turns  forward  to  open  into  the  internal  saphenous,  or  one  of  the  branches  of  that  vein, 
immediately  below  its  opening  into  the  femoral. 

Relations. — The  external  saphenous  vein  is  covered  by  the  superficial  fascia,  which 
separates  it  from  the  skin,  and  it  covers  the  externeil  saphenous  nerve,  from  which  it  is 
separated  by  a  layer  of  fascia ;  it  crosses  this  nerve  twice,  being  at  first  situated  to  the 
inner  side,  then  to  the  outer  side,  and  again  on  the  inner  side  of  the  nerve. 

The  external  saphenous  vein  communicates  with  the  deep  veins  only,  behind  the  ex- 
ternal malleolus,  and  upon  the  dorsum  of  the  foot. 

This  vein  has  only  two  valves,  one  of  which  is  situated  immediately  before  its  open- 
ing into  the  popliteal  vein. 

Such  are  the  veins  of  the  lower  extremity.  The  analogy  which  exists  between  the  in- 
ternal dorsal  branch  of  the  foot  and  the  cephalic  vein  of  the  thumb  ;  between  the  exter- 
n£il  dorsal  branch  and  the  vena  salvatella ;  between  the  external  saphenous  and  the  ra- 
dial and  cephalic  veins ;  between  the  internal  saphenous  and  the  ulnar  and  basilic  veins, 
cannot  be  doubted.  There  is  no  branch  in  the  lower  extremity  analogous  to  the  median 
vein. 


THE  VEINS  OF  THE  SPINE. 
General  Remarks. — The  Superficial  Veins  of  the  Spine. — The  Anterior  Superficial  Spinal 
Veins,  viz.,  the  Cheater  Azygos — the  Lesser  Azygos — the  Left  Superior  Vertehro-costals 
— the  Right  Vertebro-costals — the  Vertebro-lumbar — the  Ilio-lumbar,  and  Middle  and  Lat- 
eral Sacral — the  Anterior  Superficial  Spinal  Veins  in  the  Neck. — The  Posterior  Superfi- 
cial Spinal  Veins. — The  Deep  Spinal  or  Intraspinal  Veins — the  Anterior  Longitudinal, 
and  the  Transverse  Veins  or  Plexuses,  and  the  Vein^  of  the  Vertebra — the  Posterior  and 
the  Posterior  and  Lateral  Transverse  Veins  or  Plexuses — the  Medullary  Veins. — General 
Remarks  on  the  Veins  of  the  Spine. 

The  spinal  or  rachidian  veins  constitute  a  very  important  part  of  the  venous  system, 
which  has  only  recently  been  specially  studied. 

These  veins  differ,  in  many  respects,  from  the  spinal  arteries,  so  that  the  description 
of  the  one  does  not  afford  much  assistance  in  the  study  of  the  other ;  nevertheless,  I 
shall  frequently  have  occasion  to  point  out  some  remarkable  analogies  between  these  two 
sets  of  vessels. 

The  spinal  veins  are  arranged  most  distinctly  as  venae  comites  and  supplementary  veins. 

We  shall  divide  them  into  the  veins  exterior  to  the  spine  or  the  superficial  veins,  and 
the  wms  in  the  interior  of  the  spinal  canal,  or  the  deep  veins. 

The  Superficial  Veins  of  the  Spine. 
The  superficial  veins  of  the  spine  may  be  subdivided  into  the  anterior  and  posterior. 

The  Anterior  Superficial  Rachidian  Veins. 
The  anterior  superficial  rachidian  or  spinal  veins  (see  fig.  223)  comprise  the  vena  azy- 
gos major,  the  vena  azygos  minor,  the  common  trunk  of  the  right  superior  intercostals, 
that  of  the  left  superior  intercostals,  the  vertebro-lumbar  and  ilio-lumbar  veins,  and  the 
lateral  and  middle  sacral  veins ;  in  the  neck,  the  ascending  cervical  and  the  vertebral 
veins. 

The  Greater  Azygos  Vein. 
The  vena  azygos  major  (a  «',^^.223)  is  a  large  single  vein  (dC^rof'  without  a  rellow), 


606 


ANGEIOLOGY. 


Fig.  223. 


situated  along  the  vertebral  column ;  it  commences  {a')  in  the  lumbar  region,  and  termi- 
nates at  the  upper  part  of  the  thorax  by  opening  into  the  vena  cava  superior. 

Its  origin  is  subject  to  much  variety.  It  very  rarely  arises  from  the  trunk  of  the  inle 
rior  vena  cava  itself,  with  which,  however,  it  almost  always  communicates  by  small 
branches.  It  generally  forms  the  continuation  of  a  series  of  anastomoses,  which  sur- 
round the  bases  of  the  right  transverse  processes  of  the  lumbar  vertebrae,  and  which  may 
be  called  after  some  authors  the  ascending  lumbar  vein  {b,  on  the  right  side) ;  sometimes 
it  arises  from  the  trunk  of  the  last  vertebro-costal,  or  the  first  vertebro-lumbar  vein :  we 
rarely  find  a  branch  of  origin  from  the  renal  or  supra-renal  veins.  It  often  has  two  ori- 
gins, one  from  the  ascending  lumbar,  and  the  other  from  the  first  vertebro-lumbar,  or 
last  vertebro-costal  vein.  The  vena  azygos,  almost  immediately  after  its  origin,  passes 
from  the  abdominal  into  the  thoracic  cavity,  through  the  aortic  opening  in  the  diaphragm, 
ascends  upon  the  right  side  of  the  bodies  of  the  thoracic  vertebrae,  as  high  as  the  third 
intercostal  space,  i.  e.,  between  the  third  and  fourth  ribs, 
where  it  curves  forward,  forming,  like  the  aorta,  an  arch, 
which  passes  over  and  embraces  the  right  bronchus,  and  opens 
into  the  back  of  the  vena  cava  superior,  as  that  vein  is  enter- 
ing the  pericardium. 

During  its  course  the  vena  azygos  is  in  contact  with  the 
vertebred  column,  and  is  situated  in  the  posterior  mediasti- 
num, on  the  right  side  of  the  aorta  and  of  the  thoracic  duct 
{t  t),  which  runs  parallel  to  it ;  it  lies  in  front  of  the  right  in- 
tercostal arteries,  and  crosses  them  at  right  angles.  It  va- 
ries in  size,  according  to  the  number  of  branches  which  it  re- 
ceives, but  gradually  increases  from  below  upward. 

The  question  of  the  existence  of  valves  in  the  vena  azy 
gos  has  given  rise  to  much  discussion.  It  appears  to  me  to 
be  settled  in  the  negative. 

The  vena  azygos  is  joined  in  front  by  the  right  bronchial 
vein  and  some  oesophageal  and  mediastinal  veins  ;  on  the  right 
side  by  the  eight  inferior  vertebro-costal  veins  (c  c)  of  that  side ; 
and  on  the  left  by  the  lesser  azygos  (d)  and  the  common  trunk 
(e)  of  the  left  superior  intercostal  veins. 

Before  opening  into  the  superior  vena  cava,  opposite  the 
third  intercostal  space,  the  azygos  vein  receives  at  its  curve, 
either  by  a  common  trunk,  or  by  two  or  three  separate  branch- 
es, the  three  superior  right  vertebro-costal  veins,  which  some- 
times enter  the  right  brachio-cephalic  vein,  and  sometimes 
the  vena  cava  superior,  above  where  it  is  joined  by  the  vena 
azygos.  In  the  last  case  they  pass  vertically  upward  ;  in  the 
second  they  are  directed  almost  vertically  downward. 

The  Semi-azygos,  or  Lesser  Jlzygos  Vein. 

The  lesser  azygos  vein  {d  d,'  azygos  minor,  semi-azygos) 
may  be  regarded  as  the  common  trunk  of  the  three,  four,  or 
five  inferior  vertebro-costal  veins  (c'  c')  of  the  left  side  :  it 
opens  into  the  great  azygos  vein. 

It  commences  below  {d')  in  as  many  different  ways  as  the 
great  azygos  vein,  but  it  communicates  with  the  renal  vein 
much  more  frequently.  It  runs  upward  upon  the  left  of  the 
vertebral  coliunn,  approaches  the  median  line,  and  opens  into 
the  great  azygos  at  a  different  height  in  different  subjects.  It 
joins  the  great  azygos  either  at  right  angles  or  obliquely, 
passing  behind  the  thoracic  duct.  The  lesser  azygos  vein 
may  be  regarded  as  the  left  branch  of  origin  of  the  greater  azy- 
gos :  sometimes  it  is  extremely  large  ;  in  that  case  the  great- 
er azygos  is  directly  continuous  with  it,  and  the  right  branch 
is  very  small. 

The  lesser  azygos  vein  is  joined  by  the  four  or  five  inferior 
vertebro-costal  veins  (c'  c')  of  the  left  side.  It  also  frequent- 
ly receives  the  common  trunk  of  the  superior  vertebro-costal 
veins,  which  might  be  said  to  form  a  superior  lesser  azygos 
vein. 

The  Left  Superior  Vertebro-costal  Veins 
The  common  trunk  (e)  of  the  left  superior  intercostal  veins  (//)  might  be  called  the 
left  superior  lesser  azygos,  for  it  has  the  same  relation  to  these  veins  that  the  lesser  azy- 
gos has  to  the  inferior  intercostals  of  the  same  side.     It  runs  downward  upon  the  left 
of  the  vertebral  column,  increasing  in  size  as  it  approaches  its  termination,  which  is 


THE    INTERCOSTAL   VEINS,    ETC.  60T 

either  near  the  end  of  the  lesser  azygos,  or  in  the  greater  azygos.  Not  unfrequently  the 
common  trunk  of  the  left  superior  intercostals  bifurcates  and  opens  both  into  the  lesser 
azygos  and  into  the  left  brachio-cephaUc  vein.  In  some  cases  it  terminates  entirely 
in  the  left  brachio-cephalic  vein  :  I  have  myself  met  with  this  disposition.  I  have  seen 
the  left  superior  phrenic  and  the  mediastinal  veins  enter  the  trunk  of  the  lesser  vena 
azygos  immediately  before  its  termination. 

The  number  of  the  left  vertebro-costal  veins  which  unite  to  form  the  lesser  azygos 
vein  varies  from  three  to  seven  ;  when  only  three  or  four  of  the  highest  of  these  verte- 
bro-costal  veins  end  in  it,  the  two  or  three  lower  ones  enter  directly  into  the  greater 
azygos  vein. 

General  Remarks  on  the  Vena  Azygos  Major. — This  vein  returns  the  blood  of  the  right  and 
left  vertebro-costal  vems  to  the  heart ;  its  presence  is  rendered  necessary,  first,  in  con- 
sequence of  the  inferior  vena  cava  not  being  able  to  receive  any  veins  from  the  point 
where  it  enters  the  groove  in  the  liver  to  its  termination  in  the  right  auricle  ;  and,  sec- 
ondly, because  the  superior  vena  cava  is  also  unable  to  receive  any  veins  while  it  is 
within  the  pericardium.  The  greater  azygos  is,  therefore,  a  supplementary  vein,  a  true 
collateral  canal  which  supplies  the  place  of  the  venae  cavae,  and  receives  all  the  veins 
corresponding  to  the  branches  given  off" by  the  aorta  during  this  long  course.  These  ob- 
servations are,  for  the  most  part,  applicable  to  all  the  azygos  veins. 

Anatomical  Varieties  of  the  Azygos  Veins. — It  would  be  both  useless  and  tedious  to  no- 
tice here  all  the  varieties  that  have  been  observed  in  the  distribution  of  the  azygos  veins. 
M.  Breschet  has  described  six,  but  there  are  many  more.  The  following  is  a  very  cu- 
rious variety  :  the  greater  azygos  occupies  the  median  line  of  the  dorsal  portion  of  the 
vertebral  column,  and  is  divided  below  into  two  equal  branches,  a  right  and  a  left,  each 
of  which  receives  the  three  inferior  vertebro-costal  veins  of  its  own  sides  ;  all  the  other 
vertebro-costal  veins  end  directly  in  the  greater  azygos. 

Another  not  less  curious  variety  is  the  following :  there  are  two  equal  and  parallel 
azygos  veins,  a  right,  which  receives  all  the  right  intercostal  veins,  and  a  left,  which  re- 
ceives till  the  left  intercostals  :  the  two  main  trunks  communicate  with  each  other  oppo- 
site the  seventh  or  eighth  dorsal  vertebra  by  a  very  large  transverse  branch. 

The  Intercostal  or  Vertebro-costal  Veins. 
The  intercostal  or  vertebro-costal  veins  of  both  sides  (c  c,  c'  c',ff)  correspond  to  the  in- 
tercostal or  vertebro-costal  arteries,  the  distribution  of  which  it  is  important  to  caU  to 
mind.  We  have  seen  that  each  of  these  arteries  divides  into  two  branches  :  an  intercos- 
tal branch,  properly  so  called,  intended  for  the  intercostal  spaces  ;  and  a  spinal  branch, 
the  dorsal  division  of  which  terminates  in  the  spinal  muscles  and  the  skin,  while  its  ver- 
tebral, or  intra-spinal  division,  is  distributed  to  the  vertebrae,  to  the  spinal  cord,  and  to 
its  coverings.  In  like  manner,  the  vertebro-costal  vebis  are  formed  by  the  junction  of  the 
spinal  branch,  to  which  we  shall  presently  return,  and  the  intercostal  branch.  These 
two  sets  of  branches  unite  into  a  common  trunk,  the  vertebro-costal  vein,  which  passes 
transversely  along  the  groove  on  the  body  of  each  vertebra,  receives  some  veins  from 
the  bone  in  that  situation,  and  enters  at  a  right  angle  into  the  corresponding  axygos  vein. 

The  Lumbar  or  Vertebro-lumbar  Veins. 

In  the  lumbar  region  there  are  no  azygos  veins,  and  each  vertebro-lumbar  vein  en- 
ters separately,  or  by  a  common  trunk,  with  its  fellow  of  the  opposite  side,  into  the  back 
of  the  vena  cava  inferior.  Not  unfrequently  two  of  the  vertebro-lumbar  veins  of  the 
same  side  open  by  a  common  trunk ;  and  it  is  not  rare  to  find  the  left  superior  vertebro- 
lumbar  vein  enter  the  renal  vein. 

The  vertebro-lumbar  veins  {g)  are  distributed  very  differently  from  the  corresponding 
arteries.  Opposite  the  bases  of  the  transverse  processes  there  are  a  series  of  anasto- 
motic arches,  wliich  together  constitute,  on  each  side,  an  ascending  branch,  called  the 
ascending  lumbar  vein  {b  b),  which  communicates  above  with  the  corresponding  azygos 
vein,  and  below  with  the  ilio-lumbar  veins,  and  which  might  be  regarded  as  a  lumbar 
azygos  vein.  The  trunks  of  the  vertebro-lumbar  veins  proceed  from  this  series  of  arches 
to  the  vena  cava  ;  and  all  the  intra-spinal  and  dorsi-spinal  veins  terminate  in  it. 

The  Ilio-lumbar,  Middle  Sacral,  and  Lateral  Sacral  Veins. 

The  ilio-lumbar  vein,  which  opens  into  the  common  iliac,  is  distributed  like  the  artery 
of  that  name  ;  it  sometimes  receives  the  last  vertebro-lumbar  vein  :  it  is  joined  by  the 
great  veins  which  emerge  from  the  lower  inter- vertebral  foramina  of  the  lumbar  verte- 
brae ;  by  the  branch  which  is  continuous  in  front  of  the  fifth  lumbar  vertebra,  with  the 
series  of  arches  forming  what  may  be  called  the  lumbar  azygos ;  and,  lastly,  by  a  com- 
municating branch  from  the  lateral  sacral  veins. 

The  middle  sacral  and  lateral  sacral  veins  represent  the  azygos  veins  in  the  sacral  re- 
gion ;  they  are  joined  by  all  the  dorsi-spinal  branches  passing  out  from  the  inter-vertebral 
foramina,  and  end  in  the  common  iliac  veins. 

The  middle  sacral  vein  (A)  often  conmiences  below  by  three  branches,  a  median  in 


ANGEIOLOGY. 

front  of  the  coccyx,  and  two  lateral  and  anterior  branches.  One  of  these  joins  the  ves- 
ical plexus,  while  the  other  communicates  with  the  hemorrhoidal  veins,  and  establishes 
a  remarkable  communication  between  the  general  venous  system  and  the  system  of  the 
vena  portae. 

The  middle  sacral  vein  passes  vertically  upward,  somewhere  near  the  middle  line,  and 
opens  into  the  left  common  iliac  vein  {71)  at  a  greater  or  less  distance  from  its  junction 
with  the  right  common  iliac.    I  have  seen  it  bifurcate  above  to  enter  both  common  iliacs. 

During  its  course  it  is  joined  opposite  each  vertebra  by  some  transverse,  plexiform 
branches,  which  establish  a  free  communication  between  it  and  the  lateral  sacral  veins, 
and  which  receive  some  large  branches  from  the  bodies  of  the  sacral  vertebrae.  These 
transverse  branches  represent  the  vertebro-costal  and  vejrtebro-lumbar  veins,  which  also 
receive  the  veins  which  issue  from  the  bodies  of  the  vertebrae,  through  the  foramina, 
upon  the  inner  surface  of  those  bones. 

The  lateral  sacral  veins  (i),  of  which  there  are  always  more  than  one  on  each  side,  are 
continuous  with  the  dorsi-spinal  veins,  which  emerge  from  the  anterior  sacral  foramina ; 
there  are  generally  two,  a  superior,  which  enters  the  common  iliac  vein,  and  an  inferior, 
which  forms  a  very  remarkable  plexus,  opposite  the  great  sciatic  notch,  and  ends  in  the 
internal  iliac  vein,  or  in  its  gluteal  and  sciatic  branches. 

The  Jlnterior  Superficial  Spinal  Veins  in  the  J^eck. 

In  the  anterior  cervical  region  we  lind  transverse  plexiform  branches  (A)  opposite  each 
vertebra,  more  particularly  opposite  the  first  and  second  ;  these  plexuses  open  partly 
into  the  ascending  cervical  vein,  which  corresponds  to  the  ascending  cervical  artery, 
but  principally  into  the  vertebral  vein,  which  is  contained  within  the  canal  formed  by 
the  series  of  foramina  at  the  base  of  the  transverse  processes  of  the  cervical  vertebrae. 
These  plexiform  branches,  which  cover  the  sides  of  the  bodies  of  all  the  vertebrae,  are 
joined  by  the  veins  from  the  praevertebral  muscles,  by  the  articular  veins,  and  by  the 
anterior  osseous  veins  from  the  bodies  of  the  corresponding  vertebrae. 

The  vertebral  veins  and  the  ascending  cervical  veins  may  therefore  be  said  to  repre- 
sent the  azygos  veins  in  the  cervical  region. 

The  Posterior  Superficial  Spinal  Veins. 

The  posterior  superficial  spinal  veins  commence  in  the  skin,  and  in  the  muscles  of  the 
vertebral  grooves  :  some  of  them  closely  accompany  the  arteries ;  for  example,  those 
that  pass  between  the  muscles  of  the  vertebral  grooves  ;  the  others  have  a  peculiar  dis- 
tribution, and  require  a  special  description. 

These  veins,  which  are  called  dorsi-spinales  by  MM.  Dupuytren  and  Breschet,  form 
an  exceedingly  complicated  network,  the  meshes  of  which  surround  the  spinous  process- 
es and  laminae,  and  the  transverse  and  articular  processes  of  all  the  vertebrae :  these 
meshes  are  more  numerous  in  proportion  as  the  injection  is  more  perfect. 

After  a  successful  injection,  we  sometimes  find  along  the  summits  of  the  spinous  pro- 
cesses, especially  in  the  dorsal  and  cervical  regions,  certain  median  longitudinal  veins, 
from  which  the  interosseous  branches  proceed.  These  latter  run  forward,  on  each  side 
of,  and  in  contact  with,  the  inter-spinous  ligaments.  Having  reached  the  base  of  the 
corresponding  spinous  process,  they  pass  outward,  opposite  the  intervals  between  the 
laminae  of  the  vertebrae,  as  far  as  the  bases  of  the  transverse  processes,  and  then  divide 
into  two  branches  :  one  of  these  ascends,  and  anastomoses  with  the  descending  branch 
from  the  vein  above ;  while  the  other  branch  descends,  and  anastomoses  with  the  as- 
cending branch  of  the  vein  below.  It  follows,  therefore,  that  around  the  transverse  pro- 
cesses and  the  laminae  of  the  vertebrae  there  is  a  series  of  venous  circles,  which  com- 
municate, opposite  each  inter- vertebral  foramen,  with  the  veins  contained  in  the  interior 
of  the  spine. 

The  posterior  superficial  spinal  veins  in  the  neck  have  a  much  more  complicated  ar- 
rangement, and,  indeed,  form  a  plexus.  Moreover,  we  generally  find,  between  the  com- 
plexus  and  the  semi-spinalis  colli,  two  longitudinal  veins,  which  appear  to  me  to  deserve 
a  jiarticular  description,  under  the  name  of  the  posterior  jugular  veins. 

The  posterior  jugular  veins  commence  between  the  occipital  bone  and  the  atlas,  pass 
tortuously  out  from  the  interval  between  these  bones,  run  downward  and  inward,  and, 
opposite  the  spinous  process  of  the  axis,  the  veins  of  the  two  sides  anastomose  by  a 
transverse  branch.  They  then  change  their  direction,  pass  downward  and  outward,  and 
having  reached  the  lower  part  of  the  neck,  turn  forward,  between  the  seventh  cervical 
vertebra  and  the  first  rib,  and  open  into  the  back  of  the  brachio-cephalic  vein  behind  the 
vertebral  vein.  The  two  posterior  jugular  veins  are  therefore  arranged  in  the  form  of 
the  letter  X. 

The  posterior  jugular  vein,  which  does  not  always  exist,  for  its  branches  of  origin 
sometimes  remain  separate,  seems  to  be  inversely  proportioned  to  the  vertebral  vein, 
with  which  it  communicates  opposite  each  inter-transverse  space.  It  has  appeared  to 
me  to  communicate  above  with  the  deep  occipital  and  the  mastoid  veins,  with  the  veins 
situated  in  the  spinal  caned,  and  with  the  interned  jugular  vein.    Throughout  the  whole 


THE    INTRA-SPINAL   VEINS.  OOII 

01  Its  course,  it  communicates  freely,  opposite  each  inter-vertebral  foramen,  with  the 
veins  contained  in  the  interior  of  the  spinal  canal,  and  with  the  vertebral  vein. 

The  Deep  Spinal  or  Intra-spinal  Veins. 

The  veins  in  the  interior  of  the  spine  comprise  the  proper  veins  of  the  spinal  cord,  and 
the  veins  situated  between  the  bones  and  the  dura  mater,  which  are  subdivided  into  the 
anterior  and  the  posterior  longitudinal  veins  or  plexuses,  and  the  transverse  veins  or  plexus- 
es ;  the  latter  establishing  a  free  communication  between  all  four  of  the  longitudinal 
veins  or  plexuses,  opposite  each  vertebra. 

Before  describing  the  veins  situated  between  the  bones  and  the  dura  mater,  I  must 
state,  in  a  few  words,  what  is  the  arrangement  of  the  proper  arteries  of  the  vertebras. 

The  spinal  branches  which  are  given  off  on  each  side  of  the  body  by  the  vertebral  ar- 
tery in  the  neck,  by  the  intercostal  arteries  in  the  back,  by  the  lumbar  arteries  in  the 
loins,  and  by  the  lateral  sacral  arteries  in  the  pelvis,  enter  the  spinal  canal  through  the 
several  inter- vertebral  foramina,  and  then  each  of  them  divides  into  an  ascending  and  a 
descending  branch ;  the  ascending  branch  runs  upward  upon  the  lateral  part  of  the  body 
of  the  vertebra  above,  and  anastomoses  with  the  descending  branch  of  the  spinal  artery 
above  it,  while  the  descending  branch  anastomoses  with  the  ascending  branch  of  the 
artery  below.  Each  of  the  anastomotic  arches  thus  formed  has  its  concavity  directed 
outward ;  so  that  there  is  a  series  of  arterial  arches,  united  at  their  extremities,  situ- 
ated upon  each  side  of  the  posterior  surface  of  the  bodies  of  all  the  vertebra.  From  the 
convexity  of  each  arch  two  transverse  branches  are  given  off,  one  running  above  and 
the  other  below  the  small  foramina  upon  the  posterior  surface  of  the  body  of  the  corre- 
sponding vertebra.  The  cribriform  portion  of  the  bone  is  thus  surrounded  by  the  arte- 
rial arches  with  their  transverse  branches  ;  and  from  all  points  of  the  polygon  which 
they  form  small  arteries  are  given  off,  which  penetrate  into  the  substance  of  each  ver- 
tebra, and  anastomose  with  the  arterial  twigs  that  enter  the  anterior  surface  of  the  body 
of  the  vertebra. 

The  arrangement  of  these  arteries  gives  a  perfect  idea  of  that  of  the  veins  known  as 
the  anterior  longitudiruU  veins  or  plexuses,  and  of  the  transverse  plexuses,  which  pass  from 
one  to  the  other. 

The  ^Interior  Longitudinal  Intra-spinal  Veins  or  Plexuses,  the  Transverse 
PlexuseSy  and  the  Proper  Veins  of  the  Bodies  of  the  Vertebra. 

Dissection. — Remove  the  arches  of  the  vertebrae,  and  the  spinal  cord  and  its  coverings. 
The  plexus  may  also  be  viewed  from  the  front,  by  carefully  sawing  through  the  pedicles 
and  then  removing  the  bodies  of  the  vertebrae. 

The  anterior  longitudinal  plexuses,  described  by  Chaussier,  but  still  more  correctly  by 
Breschet,  form  two  venous  trunks,  named  the  great  anterior  longitudinal  veins,  extending 
from  the  foramen  magnum  to  the  base  of  the  coccyx,  one  on  each  side  of  the  posterior 
common  vertebral  ligament,  and  therefore  upon  the  sides  of  the  posterior  surface  of  the 
bodies  of  the  vertebrae,  and  on  the  inner  side  of  their  pedicles.  These  veins,  improperly 
called  vertebral  sinuses,  communicate  together  opposite  each  vertebra  by  a  transverse 
plexus,  situated  between  the  body  of  the  vertebra  and  the  posterior  common  ligament. 
These  longitudinal  plexuses  are  less  developed  in  the  cervical  and  sacral  regions.  It  is 
probable  that  in  the  neck  their  place  is  supplied  by  the  vertebral  veins. 

It  would  be  in  vain  to  consider  these  plexuses  as  having  a  distinct  origin,  course,  and 
termination ;  the  description  given  above  of  the  distribution  of  the  arteries  is  applicable 
to  the  veins  in  every  respect :  thus,  the  venous  plexuses  are  formed  by  a  series  of  plex- 
iform  arches,  which  embrace  the  pedicles  of  each  vertebra,  have  their  concavity  directed 
outward  and  their  convexity  inward,  and  the  extremities  of  which  anastomose  together 
opposite  the  inter- vertebral  foramina,  where  they  communicate  with  the  branches  on  the 
outside  of  the  spine,  and  assist  in  the  formation  of  the  vertebro-lumbar  and  vertebro- 
costal veins,  and,  consequently,  of  the  azygos  veins.  From  the  convexity  of  each  arch 
proceeds  a  transverse  plexus,  which  goes  to  join  with  its  fellow  of  the  opposite  side ; 
and,  just  as  we  have  seen  that  the  transverse  arteries  extending  from  one  arterial  arch 
to  another  give  off  branches  to  the  bodies  of  the  vertebrae,  so,  in  like  manner,  the  trans- 
verse venous  plexuses  receive  the  veins  which  emerge  from  the  body  of  each  vertebra. 

The  arrangement  of  the  veins  or  plexuses  just  described  explains  the  alternate  en- 
largements and  contractions  observed  in  different  parts  of  the  anterior  longitudinal  plex- 
uses. The  rare  interruptions  described  by  M.  Bresche(  I  believe  to  depend  upon  im- 
perfect injections,  which  succeed  so  differently  in  different  subjects. 

The  anterior  longitudinal  veins  or  plexuses  cannot  be  regarded  as  sinuses,  for  they  are 
not  contained  in  a  fibrous  sheath,  like  the  veins  of  the  dura  mater,  nor  are  they  reduced* 
merely  to  the  lining  membrane  of  the  veins.  Notwithstanding  their  extreme  tenuity, 
we  can  recognise  an  external  coat,  and  the  posterior  common  ligament  does  not  covet 
them  behind.  Nor  is  the  term  sinus  more  applicable  to  the  transverse  plexuses,  although 
they  are  situated  between  the  bodies  of  the  vertebrae  and  the  posterior  common  ligament,. 
for  the  ligament  merely  covers  them  without  forming  a  sheath  for  them. 

4H 


610  ANGEIOLOGY. 

The  Proper  Veins  of  the  Bodies  of  the  Vertebra. — The  foramina  upon  the  posterior  sux- 
face  of  the  body  of  each  vertebra,  which  are  generally  proportioned  to  the  size  of  the  ver- 
tebra, are  principally  intended  for  the  proper  veins  of  the  bodies  of  their  bones  :  the  ar- 
teries are  much  smaller,  and  though  they  enter  by  the  same  openings,  they  occupy  but  a 
small  part  of  their  areas.  These  veins  belong  to  that  system  of  venous  canals  found  in 
the  substance  of  bones,  which  we  have  already  noticed  as  existing  in  the  bones  of  the 
cranium.  Their  chief  varieties  have  been  correctly  described  and  delineated  by  M.  Bres- 
chet.  These  venous  canals,  which  are  more  developed  in  the  old  than  in  young  sub- 
jects, occupy  the  centre  of  the  body  of  the  vertebra,  and  always  run  parallel  to  the  up- 
per and  lower  surfaces  of  the  bone  :  they  arise  from  all  parts  of  the  circumference  of  the 
vertebra,  communicating  with  the  veins  which  enter  by  the  foramina  on  its  anterior  sur- 
face, and  converge  towards  the  principal  foramen,  or  foramina,  upon  its  posterior  eis- 
pect.  They  frequently  enter  a  semicircular  canal,  which  has  its  convexity  directed  for- 
ward, and  gives  off  from  its  concavity  a  venous  canal,  which  opens  directly  into  the 
transverse  plexus  :  the  lateral  veins  of  the  body  of  the  vertebra  open  into  the  extremities 
of  this  semicircular  canal ;  while  within  the  venous  canals  of  the  vertebrae,  the  veins  are 
reduced  to  their  lining  membrane,  like  the  veins  in  the  canals  of  the  cranial  bones. 

The  transverse  plexuses,  therefore,  collect  the  blood  from  the  bodies  of  the  vertebra), 
and  transmit  it  to  the  anterior  longitudinal  plexuses. 

The  Posterior  IntrU'Spinal  Veins  or  Plexuses,  and  the  Posterior  and  Lateral 
Transverse  Plexuses. 

The  posterior  intraspinal  plexuses,  much  smaller  than  the  anterior,  are  situated  one  on 
each  side  between  the  vertebral  laminae  and  ligamenta  subflava  behind,  and  the  dura 
mater  in  front.  These  veins  are  rarely  injected  along  the  whole  length  of  the  spine,  and 
hence  they  sometimes  appear  to  exist  only  in  the  dorsal  region.  They  communicate  op- 
posite each  vertebra,  by  means  of  posterior  transverse  plexuses,  or  by  transverse  veins. 
They  communicate  with  the  anterior  longitudinal  plexuses  by  small  lateral  transverse 
plexuses,  which  pass  from  behind  forward.  It  follows,  therefore,  that  the  veins  within 
the  spine,  but  external  to  the  coverings  of  the  cord,  consist  of  four  longitudinal  plexuses, 
all  of  which  are  connected  by  a  transverse  circular  plexus  opposite  each  vertebra.  A 
strict  analogy  may  be  said  to  exist  between  the  sinuses  of  the  cranium  and  the  intra-spi- 
nal  plexuses  ;  an  analogy  which  did  not  escape  the  notice  of  the  ancients,  as  the  com- 
mon application  of  the  term  sinus  by  them  to  the  veins  of  the  cranium  and  to  those  of  the 
spine  would  seem  to  indicate.  Thus,  in  the  cranium  we  find  certain  longitudinal  sinus- 
es, that  is,  those  which  run  from  before  backward,  viz.,  the  superior  longitudinal  sinus, 
the  straight  sinus,  and  the  posterior  occipital  sinuses  ;  also,  the  superior  and  inferior  pe- 
trosal sinuses,  the  cavernous  sinuses,  and  the  right  and  left  lateral  sinuses.  The  former 
set  represent  the  posterior  intra-spinal  plexuses  ;  the  latter  correspond  to  the  anterior  in- 
tra-spinal  plexuses. 

In  the  cranium  we  also  find  certain  transverse  sinuses,  viz.,  the  basilar  or  transverse 
occipital  sinuses  and  canals,  and  the  coronary  sinus,  which  exactly  correspond  to  the 
transverse  plexuses,  extending  from  one  anterior  intra-spinal  plexus  to  the  other.  We 
sometimes  find  two  or  three  transverse  venous  plexuses  in  the  basilar  groove  of  the  oc- 
cipital bone. 

Lastly,  may  we  not  compare  the  veins  on  the  outer  surfaces  of  the  spine  to  the  occipital, 
frontal,  and  temporal  veins  ;  and  do  not  the  veins  passing  through  the  posterior  lacerated 
foramen  and  the  sphenoidal  fissure,  which  we  have  regarded  as  representing  the  inter- 
vertebral foramina  (see  Osteology),  establish  a  communication  between  the  veins  on 
the  inside  and  those  on  the  outside  of  the  cranium,  just  as  the  veins  which  escape  through 
the  inter-vertebral  foramina  connect  together  the  superficial  and  the  intra-spinal  veins  1 

The  anterior  and  posterior  deep  spinal  veins  communicate  with  the  superficial  veins 
of  the  spine  at  the  inter-vertebral  foramina  so  freely,  that  the  circulation  would  not  be 
interfered  with  even  if  a  considerable  amount  of  obstruction  existed.  I  have  already 
stated  (see  VERTEBRiE)  that  the  diameter  of  the  inter-vertebral  foramina  is  in  relation, 
not  with  the  size  of  the  nervous  ganglia,  but  rather  with  that  of  the  veins,  which  estab- 
lish a  communication  between  the  superficial  and  intra-spinal  venous  systems. 

The  Proper  Veins  of  the  Spinal  Cord,  or  the  Medullary  Veins. 

If  we  examine  the  pia  mater  of  the  spinal  cord,  even  without  having  injected  it,  in  the 
body  of  a  person  who  has  died  suddenly,  as  in  that  of  a  new-born  infant  after  death  from 
asphyxia  or  apoplexy,  the  surface  of  the  pia  mater  will  be  found  covered  by  very  tortu- 
ous veins,  which  emerge  from  the  posterior  median  furrow  of  the  spinal  cord.  This  ve- 
nous network,  which  is  spread  over  the  whole  surface  of  the  cord,  gives  off  opposite  the 
roots  of  each  nerve  a  small  vein,  which  runs  directly  between  those  roots,  enters  the 
corresponding  inter-vertebral  foramen,  is  enclosed  with  the  nerve  in  the  sheath  formed 
by  the  dura  mater,  and  having  emerged  from  that  sheath,  opens  into  the  large  vein  sit- 
uated in  the  inter-vertebral  foramen. 

There  is,  therefore,  this  difference  between  the  proper  veins  and  arteries  of  the  spinal 


THE    LYMPHATIC   SYSTEM.  811 

cord,  that  the  number  of  veins  is  equal  to  that  of  the  nerves ;  while  the  arteries  are  less 
numerous,  and  enter  the  fibrous  sheaths  of  the  nerves  only  at  intervals,  and  in  propor- 
tion as  the  preceding  arteries  are  exhausted.  Moreover,  the  anterior  and  posterior  spi- 
nal veins,  like  their  corresponding  arteries,  may  be  regarded  as  belonging  only  to  the  up- 
per part  of  the  cord,  and  not  as  being  intended  to  traverse  its  whole  length. 

General  Remarks  on  the  Veins  of  the  Spine. 

The  veins  of  the  spine  maybe  regarded,  in  reference  to  the  general  circulation,  as  es- 
tablishing an  unbroken  communication  between  the  veins  of  all  parts  of  the  trunk  ;  so 
that  we  can  suppose  one  of  the  venae  cavae  to  be  obliterated,  without  the  venous  circu- 
lation being  interrupted.  The  greater  azygos  itself,  which  is  generally  regarded  as  the 
principal  means  of  communication  between  the  two  venae  cavae,  is  not,  however,  neces- 
sary, when  we  consider  the  arrangement  of  the  anterior  and  posterior  spinal  plexuses. 
Thus,  I  have  sometimes  seen  the  inferior,  and  sometimes  the  superior  vena  cava  oblit- 
erated without  any  apparent  increase  in  the  diameter  of  the  vena  azygos,  and,  what  will 
perhaps  be  thought  surprising,  without  oedema,  either  of  the  upper  or  lower  extremities. 

Supposing  the  vena  cava  ascendens  to  be  obstructed  from  the  entrance  of  the  hepatic 
veins  down  to  the  renal  veins,  the  blood  would  then  flow  back  by  the  vertebro-lumbar 
veins  into  the  plexuses  contained  within  the  spinal  canal ;  through  these  plexuses,  it 
would  ascend  to  the  vertebro-costal  veins,  from  thence  to  the  azygos  veins,  and  through 
them  into  the  superior  vena  cava. 

If  all  the  jugular  veins  were  obliterated,  the  venous  circulation  in  the  head  would  still 
continue,  and  would  be  carried  on  through  the  spinal  veins.  I  have  tied  the  two  exter- 
nal jugular  veins  in  a  dog.  The  animal  showed  no  sign  of  cerebral  congestion :  after 
opening  the  body,  I  did  not  find  any  increase  of  size  in  the  small  veins  which  accom- 
pany the  carotid  arteries,  and  which  in  those  animals  are  naturally  very  smalL  In  this 
case,  the  circulation  was  evidently  carried  on  by  means  of  the  spinal  veins. 


THE  LYMPHATIC  SYSTEM. 


Definition,  History,  and  general  View  of  the  Lymphatic  System. — Origin. — Course. — Tcrim- 
nation  and  Structure  of  the  Lymphatic  Vessels. — The  Lymphatic  Glands. — Preparation  oj 
the  Lymphatic  Vessels  and  Glands. 

The  term  lymphatic  vessels  is  applied  to  certain  transparent  tubes  provided  with  valves, 
and  conveying  either  lymph  or  chyle,  which  pass  through  small,  rounded,  glanduliform 
bodies  called  lymphatic  glands,  and  in  all  cases  empty  themselves  into  the  venous  sys- 
tem, to  which,  indeed,  they  may  be  said  to  form  an  appendage. 

From  their  tenuity  and  transparence,  these  vessels  for  a  long  time  escaped  the  notice 
of  anatomists.  The  thoracic  duct  was  discovered  by  Eustachius  in  1565.  The  lac- 
teals  were  discovered  in  1622  by  Gaspard  Asellius,  who,  by  a  lucky  chance,  while  seek- 
ing quite  another  object,  discovered  certain  vessels  filled  with  chyle.  In  1641,  Pecquet 
discovered  the  receptaculum  chyli,  and  showed  that  the  lacteals  entered  the  thoracic 
duct,  and  not  the  liver,  as  Asellius  and  all  his  contemporaries  believed. 

Rudbeck,  Thomas  Bartholin,  and  JolyfF  dispute  the  honour  of  having  discovered  the 
l)Tnphatic  vessels,  properly  so  called,  in  contradistinction  to  the  lacteals  or  chyliferous 
vessels. 

Mascagni  devoted  a  great  part  of  his  life  to  the  study  of  the  lymphatic  system  ;  and 
his  work,  ornamented  by  magnificent  plates,  is  a  monument  of  science,  which  should  be 
taken  for  a  model  by  all  who  are  engaged  in  anatomical  inquiries.  Lastly,  within  the 
last  few  years,  MM.  Fohmann,  Lauth,  Lippi,  Panizza,  and  Rossi  have  thrown  light  upon 
some  most  important  points  in  the  anatomy  of  this  system. 

In  describing  this  system  of  vessels,  the  lacteals,  or  the  Ijntnphatics  containing  chyle, 
have  commonly  been  separated  from  the  lymphatics,  properly  so  called,  or  the  vessels 
containing  lymph.  This  distinction,  however,  is  not  warranted  by  anatomy,  for  the  two 
sets  of  vessels  are  perfectly  identical  in  structure. 

The  IjTnphatic  system  offers  many  analogies  with  the  venous  system  ;  but  there  ar 
also  no  less  remarkable  differences  between  the  two. 

Like  the  venous  system,  it  consists,  as  a  whole,  of  afferent  or  converging  vessels 
which  arise  from  all  parts  of  the  body,  and  run  from  the  periphery  towards  the  centre. 

Like  the  veins,  the  lymphatics  are  divided  into  two  sets  :  a  srib-cutaneous  set,  which, 
in  general,  accompanies  the  superficial  veins  of  the  limbs  ;  and  a  deep  set,  which  follows 
the  course  of  the  deep  arteries  and  veins  ;  and,  lastly,  the  lymphatics  resemble  the  veins 
in  being  provided  with  valves. 

The  lymphatics  differ  from  the  veins  in  passing  through  certain  bodies  improperly 
called  glands,  which,  at  intervals,  intercept  their  course.  They  differ  from  the  veins, 
also,  in  their  arrangement ;  for  they  do  not  successively  unite  into  larger  and  larger 
branches,  and  these  into  trunks,  but  they  scarcely  increase  in  size  from  their  origin  to 
their  termination  ;  and,  though  they  communicate  with  each  other  by  numerous  anasto- 


6t$  ANGEIOLOGY. 

moses,  each  of  them  follows,  as  it  were,  an  independent  course  :  lastly,  the  blood  which 
circulates  in  the  veins  is  still,  though  indirectly,  under  the  influence  of  the  heart's  ac- 
tion, while  the  onward  movement  of  the  lymph  is  exclusively  dependant  upon  the  pari- 
etes  of  the  vessels. 

Before  proceeding  to  the  special  description  of  the  lymphatics,  we  shall  make  some 
general  remarks  upon  the  origin,  course,  and  termination  of  these  vessels. 

Origin  of  the  Lymphatics. 

Tlie  origin  of  the  lymphatics,  hke  every  point  connected  with  the  minute  structure  of 
the  tissues,  is  yet  a  new  subject  for  inquiry.* 

It  has  been  said  that  the  Ijmnphatics  are  continuous  with  the  arteries,  so  that,  accord- 
ing to  this  hypothesis,  the  arteries  are  continuous  with  two  kinds  of  vessels,  viz.,  with 
the  lymphatics,  which  carry  off  the  serum,  and  with  the  veins,  which  transmit  the  col- 
oured part  of  the  blood.  The  continuity  of  the  arteries  with  the  lymphatics  has  been 
admitted,  in  consequence  of  its  having  been  observed  that  injections  thrown  into  the 
arteries  passed  into  the  lymphatics.  I  have  frequently  seen  this  in  injecting  the  spleen 
and  the  liver ;  but  it  was  only  when  the  injection  was  pushed  in  with  great  and  contin- 
ued force  :  so  that  it  is  possible,  as  thought  by  Hunter,  Monro,  and  Meckel,  that,  in  these 
cases,  some  of  the  vessels  had  been  ruptured,  and  the  injection  extravasated  ;  or,  what 
is  still  more  probable,  there  may  have  been  transudation  through  the  pores  of  the  tis- 
sues. Microscopical  observations  show  most  distinctly  that  the  arteries  are  continuous 
with  the  veins  ;  but  there  is  no  fact  to  demonstrate  the  continuity  of  the  arteries  with 
the  lymphatics. 

The  origin  of  the  lymphatics  can  be  actually  shovra  only  upon  free  surfaces,  such  as 
the  mucous  membranes,  the  skin,  the  serous  and  synovial  membranes,  and  the  lining 
membranes  of  arteries  and  veins  ;  so  that,  in  the  actual  state  of  our  knowledge,  it  might 
be  maintained  that  the  lymphatic  vessels  arise  exclusively  from  all  the  free  surfaces. 

All  the  lymphatics  arise  by  a  network  of  such  tenuity  that,  when  .injected  with  mer- 
cury, the  whole  surface  appears  changed  into  a  metallic  layer. 

About  eight  years  since,  having  introduced  at  random  a  tube  filled  with  mercury  for 
injecting  the  lymphatics  into  the  pituitary  membrane  in  a  calf,  I  was  astonished  to  find 
the  surface  covered  by  a  metallic  pellicle  :  I  repeated  the  experiment  frequently,  and 
constantly  found  that  the  pellicle  was  not  caused  by  extravasation,  for  the  mercury  ran 
in  determinate  lines,  forming  plexuses  of  different  kinds  ;  also  that,  to  succeed  in  this 
experiment,  it  was  necessary  to  puncture  the  membrane  very  superficially,  or  the  mer- 
cury would  run  into  the  subjacent  plexus  of  veins;  and,  lastly,  that  there  was  no  com- 
munication between  that  plexus  of  veins  and  the  more  superficial  network,  which  I  sus- 
pected to  consist  of  lymphatic  vessels,  for  it  exactly  resembled  the  network  of  those 
vessels  in  the  peritoneum  covering  the  liver.  I  ascertained  that  the  same  structure  ex- 
isted in  the  skin ;  in  the  lingual,  buccal,  and  vaginal  mucous  membranes  ;  in  the  con- 
junctiva ;  and,  lastly,  in  the  uterine  mucous  membrane  of  a  sow  which  had  lately  lit- 
tered. I  showed  this  lymphatic  network  of  the  pituitary  membrane  in  several  of  my 
lectures  ;  and  lately,  having  again  examined  the  subject  for  the  purposes  of  the  present 
work,  I  have  ascertained  that  this  network  exists  upon  all  the  free  surfaces,  that  it  com- 
municates with  the  lymphatics,  and  that  it  is  possible  to  inject  those  vessels  and  the 
lymphatic  glands  by  introducing  the  pipe  very  superficially  into  the  surfaces  of  these 
membranes.!  I  may  be  permitted  to  observe,  that  it  is  only  a  few  months  since  I  be- 
came acquainted  with  the  splendid  work  of  M.  Panizza,  of  Pavia,  upon  the  lymphatic  ves- 
sels of  the  testicles  {Osservazioni  Antropo-zootomico  Fisiologiche,  1830) ;  and  with  M.  Foh- 
mann's  last  very  important  memoir  {Mimoire  sur  les  Vaisseaux  Lymphatiques  de  la  Peau, 
des  Membranes  Muqueuses,  Sereuses,  du  Tissu  Nerveux,  ct  des  Muscles,  1833). 

Origin  of  the  Lymphatics  from  the  Mucous  Membranes. — The  villi  found  upon  the  mu- 
cous membrane  of  the  small  intestines  contain,  in  their  centre,  a  cavity,  named  the  am- 
pulla of  lAeberkuhn,  which  I  have  seen  in  one  instance  filled  with  tuberculous  matter. 
{Anat.  Pathol,  \w.  ii.)  Still,  I  have  never  been  able  to  discover  any  open  orifice  on  the 
summit  of  that  villus.J  Independently  of  these  cavities  within  the  villi,  which  are  proper 
to  the  system  of  lacteal  vessels,  the  thin  pellicle  of  the  mucous  membranes  which  can- 
not be  injected  from  the  arteries  or  veins  {vide  p.  370),  when  carefully  and  very  super- 
ficially punctured  by  the  pipe  of  a  mercurial  injecting  apparatus,  is  covered  by  a  metallic 
pellicle.  Panizza  and  Fohmann  have  proved  that  the  membrane  which  covers  the  glans 
penis  has  two  sets  of  lymphatics  :  a  superficial  and  a  deep.  M.  Fohmann  has  figured,  in 
some  very  beautiful  plates,  the  lymphatic  network  of  the  mucous  membranes  of  the  glans 
penis,  bladder,  urethra,  trachea,  bronchi,  oesophagus,  stomach,  ileum,  and  colon.  This 
network  is  so  superficial,  that  the  mercury  appears  almost  uncovered  ;  it  does  not  com- 

*  Do  lymphatics  commence  in  all  parts  of  the  body  ?  It  is  true  that  absorption  is  carried  on  in  every  part, 
for  absorption  is  one  element  of  the  process  of  nutrition  ;  but,  as  it  can  be  effected  by  other  vessels  besides  the 
lymphatics,  its  occurrence  in  any  part  does  not  necessarily  involve  the  presence  of  this  peculiar  class  of  vessels. 

T  These  preparations  were  made  by  M.  Bonami,  my  prosector,  under  my  direction,  with  extreme  skill,  and 
a  zeal  above  all  praise. 

',   [For  what  is  known  conceming^  the  structure  of  the  villi,  see  note,  p.  369] 


ORIGIN    OF    THE    LYMPHATICS.  613 

municate  either  with  the  arteries  or  the  veins,  but  communicates  freely  with  the  lym- 
phatic vessels.  It  was  correctly  delineated  by  Mascagni :  according  to  that  anatomist, 
it  covers  all  the  intestinal  villi,  as  with  a  sheath,  and  does  not  appear  to  have  any  open- 
ings on  the  exterior. 

Origin  of  the  Lymphatics  from  the  Skin. — Are  the  openings  or  pores  so  evident  upon  the 
skin  when  viewed  through  a  lens,  and  from  which  drops  of  sweat  maybe  seen  to  exude, 
intended  to  serve  the  purpose  both  of  exudation  and  absorption  1  or  are  there  rather  two 
distinct  kinds  of  orifices  for  these  two  functions  1  or,  lastly,  are  these  orifices  altogether 
unconnected  with  the  absorbent  vessels  1* 

If  we  puncture  the  skin  very  superficially,  so  that  the  injecting  pipe  may  enter  imme- 
diately below  the  epidermis,  the  mercury  will  be  seen  to  run  with  great  rapidity  into 
some  very  small  vessels,  and  to  form  a  metallic  network,  precisely  like  that  already  de- 
scribed as  existing  in  the  mucous  membranes  ;  from  this  layer  proceed  sub-cutaneous 
lymphatics,  which  may  be  traced  filled  with  mercury  as  far  as  the  adjacent  lymphatic 
glands,  or  even  beyond  them.  In  order  that  this  experiment  may  succeed,  it  is  neces- 
sary that  the  skin  to  be  injected  should  be  plunged  into  hot  water. 

I  made  the  following  experiment  in  order  to  detect,  if  possible,  in  the  lymphatics  of 
the  skin,  the  mercury  absorbed  during  mercurial  frictions.  I  caused  two  dogs  to  be 
rubbed  with  mercurial  ointment  night  and  morning ;  and,  that  the  absorption  might  be 
more  complete,  I  enveloped  their  bodies  in  a  frock  made  of  skin.  These  animals  died  in 
about  eight  days  with  gangrene  of  the  gums  ;  but  I  could  not  find  in  any  part  the  slight- 
est trace  of  mercury,  although  the  frictions  were  continued  up  to  the  period  of  their 
death. 

Origin  of  the  Lymphatics  from  the  Serous  and  Synovial  Membranes. — The  same  results 
as  those  above  stated  are  obtained  by  injecting  the  serous  and  synovial  membranes. 
The  portion  of  peritoneum  covering  the  liver  is  generally  chosen  for  injecting  the  l>Tn- 
phatic  network  of  serous  membranes,  because  the  tension  and  adhesion  of  the  perito- 
neum over  the  liver  renders  it  more  easy  to  inject.  The  same  results  may  be  obtained 
by  injecting  the  costal  or  pulmonary  pleura,  the  tunica  vaginalis,  or  the  parietal  and  vis- 
ceral portions  of  the  arachnoid. 

The  synovial  membranes  may  be  injected  with  the  greatest  facility,  either  near  the 
cartilages,  where  they  are  more  tense  than  in  other  parts,  or  upon  the  ligaments,  to 
which  they  adhere. 

Origin  of  the  Lymphatics  from  the  Lining  Membrane  of  the  Veins  and,  Arteries. — ^The 
lymphatic  plexuses  upon  the  lining  membrane  of  veins  and  arteries  have  hitherto  been 
only  partially  displayed,  but  the  analogy  between  these  and  serous  membranes  is  so 
close,  that  I  have  no  doubt  of  their  identity  in  this  respect.  I  have,  moreover,  found  the 
lymphatic  vessels  of  the  aorta  filled  with  blood  in  several  cases  of  degeneration  of  the 
coats  of  that  vessel. 

Origin  of  the  Lymphatics  in  the  Free  Cellular  Tissue. — In  order  to  exhibit  the  origin  of 
the  lymphatics  in  this  situation,  I  injected  coloured  liquids,  such  as  ink,  into  the  sub- 
cutaneous and  inter-muscular  cellular  tissue  in  several  animals,  and  I  found  the  lym- 
phatic vessels  and  the  corresponding  lymphatic  glands  of  a  jet-black  colour.  I  made  a 
great  number  of  experiments  to  induce  absorption  of  mercury,  by  injecting  it  either  into 
the  cellular  tissue,  or  into  a  serous  cavity  ;  but  the  metallic  mercury  always  acted  like 
a  foreign  body,  the  mechanical  effect  of  which  produced  more  or  less  inflanunation,  but 
it  was  never  absorbed. 

I  have  found  pus  in  both  the  superficial  and  deep  lymphatics,  and  in  the  lymphatic 
glands  of  the  groin,  after  phlegmonous  erysipelas  and  acute  abscesses  of  the  leg  ;  but  it 
is  not  proved  that  the  presence  of  this  pus  was  the  result  of  absorption.  It  is  more 
probable  that  it  had  been  produced  by  inflammation  of  the  lymphatics  themselves. 

Although  it  is  impossible  to  demonstrate,  anatomically,  the  presence  of  lymphatics  in 
the  free  cellular  tissue,  it  is  most  probable  that  that  tissue,  as  well  as  the  serous  mem- 
branes, with  which  it  heis  so  many  anedogies,  is  formed  by  this  kind  of  vessels.  Mas- 
cagni stated  that  all  the  white  tissues  consist  of  lymphatic  vessels,  and  that  the  lym- 
phatic system  forms  the  basis  of  the  whole  body. 

From  the  preceding  observations,  it  may  be  stated  that,  with  the  exception  of  the 
lacteals  which  open  upon  the  summits  of  the  villi,  +  all  the  lymphatic  vessels  of  free  sur- 
faces arise  by  an  exceedingly  delicate  network ;  M.  Fohmann  believes  that  all  the  lym- 
phatics commence  by  a  network  of  closed  vessels.t 

I  have  never  been  able  to  discover  the  l)Tnphatic  networks,  either  in  the  nervous  sub- 
stance, in  muscles,  glands,  or  in  the  fibrous,  cartilaginous,  and  osseous  tissues. 

*  [These  pores  are  the  orifices  of  the  ducts  of  the  sudoriferous  glands,  which  are  imbedded  in  the  true  skin, 
or  the  sub-cutaneous  cellular  membrane,  and  have  no  direct  connexion  with  the  lymphatics.] 

+  [Whether  the  lacteals  commence  in  each  villus  by  a  network,  or  by  free  closed  extremities,  is  not  yet  de- 
termined ;  but  they  form  no  exception  to  the  rule  that  the  absorbent  vessels  arise  by  closed  extremities,  and 
not  by  open  mouths.     See  p.  370.] 

t  [These  networks  are  arranged  in  layers,  the  most  superficial  of  which  is  formed  by  the  finest  vessels,  and 
has  the  smallest  meshes.] 


m4 


ANGEIOLOGY. 


Course  of  the  Lymphatics. 

From  the  networks  above  described,  the  lymphatics  themselves  arise,  and,  in  aD  the 
organs,  are  divided  into  a  deep  and  a  superficial  set.  The  former  set  accompany  the  deep 
vessels  of  the  organ,  while  the  others  follow  the  superficial  veins  in  such  parts  of  the 
body  as  are  provided  with  them.  In  those  organs  which  are  covered  with  a  serous  coat, 
they  appear  to  be  contained  within  the  substance  of  that  membrane.  The  lymphatics 
run  parallel  with  each  other,  and  communicate  pretty  frequently  by  bifurcating,  and  then 
joining  the  neighbouring  vessels  ;  but  they  do  not  converge  towards  each  other,  nor  do 
they,  like  the  veins,  unite  successively  into  a  smaller  and  smaller  number  of  larger  and 
larger  branches  ;  thus,  their  increase  in  size  is  not  progressive  ;  and  it  might  even  be 
said  that,  throughout  their  whole  course,  they  undergo  no  decided  increase  nor  dimi- 
nution. 

Their  direction  is  slightly  tortuous.  (In^^.  224  are  shown  short  portions  of  lymphat- 
ics of  different  sizes.) 

Anastomoses. — ^We  do  not  find  in  the  lymphatics  those  numerous  and  important  anas- 
tomoses which  form  such  characteristic  points  in  the  history  of  the  arteries  and  veins. 
These  vessels  present  only  one  kind  of  anastomosis,  which  is  accomplished  in  the  fol- 
lowing manner :  A  Ijonphatic,  after  a  certain  course,  divides  into  two  equal  branches, 
which  diverge  at  a  very  acute  angle  ;  these  two  branches  anastomose  with  two  other 
lymphatics,  each  of  which  communicates  either  by  bifurcation  or  directly  with  the  neigh- 
bouring lymphatic  vessel.  This  explains  how,  by  injecting  a  single  lymphatic,  a  certain 
group  of  these  vessels  may  be  filled.  Not  unfrequently,  a  lymphatic  divides  into  two 
branches,  which,  after  a  certain  distance,  again  unite. 

During  their  course,  the  lymphatic  vessels  meet  certain  small  giandulifm-m  ladies,  the 
conglobate  glands  of  the  ancients,  but  which  are  also  called  lymphatic  ganglia,  on  account 
of  the  analogy  pointed  out  by  Soemmerring  between  them  and  the  ganglia  of  nerves ;  the 
lymphatic  glands  form  centres,  to  which  a  number  of  lymphatic  vessels  proceed,  and  are 
lost  in  them  for  a  time,  but  from  which  they  afterward  emerge. 

The  name  of  afferent  lymphatics  (vasa  afferentia,  a  a  a,  fig.  225)  is  applied  to  those 
which  enter  a  gland,  and  those  which  emerge  from  it  are  called  efferent  lymphatics  (vasa 
efferentia,  b  h). 

Do  all  the  lymphatics  necessarily  traverse  one  or  more  of  these  glands  t  Mascagni 
has  successfully  maintained  the  affirmative  in  opposition  to  Hewson  and  others,  who  as- 
sert that  they  have  seen  lymphatics  entering  directly  into  the  thoracic  duct.  Mascagni 
states  that  he  invariably  found  that  these  vessels  passed  through  one  or  more  glands. 
As  to  the  argument  derived  from  the  absence  of  dropsy  in  oases  of  obstruction  in  the 
lymphatic  glands,  Mascagni  explains  this  by  the  frequent  anastomoses  of  the  lymphatic 
vessels,  the  result  of  which  is,  that  they  communicate  with  several  series  of  glands, 
some  of  which  are  situated  at  very  great  distances. 

The  most  numerous  anastomoses  of  the  lymphatics  take  place  within  the  lymphatic 
glands  ;  thus,  if  we  inject  the  afferent  vessels  of  a  lymphatic  gland,  the  mercury  escapes 
by  its  efferent  vessels.  In  injecting  a  gland,  it  frequently  happens  that  the  mercury 
passes  not  only  into  the  efferent,  but  also  into  some  of  the  afferent  vessels. 

Size  of  the  Lymphatics. — The  lymphatics  are  generally  so  small  as  to  escape  the  no- 
tice of  the  observer  ;  but  they  may  become  enlarged  to  a  remarkable  degree.  Thus,  I 
have  seen  the  lymphatics  of  the  groin  and  of  the  uterus  as  large  as  the  thumb. 

An  attempt  has  been  made  to  draw  some  comparison  between  the  toted  capacities  of 
the  lymphatic,  venous,  and  arterial  systems  ;  but  all  that  has  been  said  respecting  this 
is  founded  upon  no  positive  data.  I  would,  moreover,  observe,  that  in  all  probability  we 
are  acquainted  with  but  a  portion  of  the  lymphatic  system. 

Termination  of  the  Lymphatics. 

According  to  the  most  generally  received  opinion,  all  the  lymphatics  terminate  in  two 
trunks,  the  thoracic  duct  and  the  great  right  lymphatic  duct;  the  latter  vessel  receives  the 
lymph  from  the  right  upper  extremity,  and  from  the  right  half  of  the  head,  neck,  and  tho- 
rax ;  the  lymphatic  vessels  of  all  the  other  parts  of  the  body  end  in  the  thoracic  duct ; 
the  lymphatic  vessels  enter  successively  into  these  two  trunks,  as  the  plumes  of  a  feath- 
er are  attached  to  its  shaft.  The  two  trunks  themselves  end  as  follows ;  the  thoracic 
duct  enters  the  left  sub-clavian  vein,  at  the  junction  of  that  vein  with  the  internal  jugu- 
lar ;  the  great  right  lymphatic  duct  terminates  in  the  right  sub-clavian  vein ;  hence  it  is 
that  the  lymphatic  system  may  be  regarded  as  an  appendage  of  the  venous  system. 

Are  the  thoracic  and  the  great  right  lymphatic  ducts,  notwithstanding  their  small  size, 
the  only  terminations  of  the  lymphatic  system]  With  this  question  may  be  connected 
another :  Are  the  lymphatics  the  exclusive  agents  of  absorption,  or  do  they  share  this 
function  with  the  veins  1 

Mascagni  appeared  to  have  established,  beyond  dispute,  that  absorption  was  performed 
by  the  lymphatics  to  the  exclusion  of  the  veins  ;  when  Magendie*  and  Delille  in  France, 

*  It  is  established,  says  M.  Magendie,  that  the  lacteals  absorb  the  chyle,  and  that  the  intestinal  veins  ab- 


TERMINATION    OF   THE   LYMPHATICS.  615 

Tiedemann  and  Gmelin  in  Germany,  and  Flandrin  and  Emmert  in  England,  relying  upon 
some  ingenious  experiments,  again  attributed  a  power  of  absorption  to  the  veins,  and 
hence  led  other  anatomists  to  undertake  still  farther  researches. 

The  inquiry  was  soon  entered  upon  by  M.  Fohmann  in  1820  and  1821,  by  M.  Lauth  in 
1824,  and  by  M.  Lippi  in  1825,  all  of  whom  again  referred  the  phenomena  of  absorption 
exclusively  to  the  lymphatics,  and  supported  that  opinion  both  by  arguments  and  facts. 

MM.  Fohmann  and  Lauth  admit  two  other  modes  of  termination  of  the  lymphatic  sys- 
tem in  the  veins  besides  the  one  already  indicated :  first,  a  direct  termination  of  the 
lymphatic  radicles  in  the  radicles  of  the  veins,  which  is  supposed  to  occur  in  the  sub- 
stance of  organs ;  and,  secondly,  a  communication  between  the  lymphatics  and  veins 
within  the  lymphatic  glands.  This  opinion,  which  seems  reconcilable  with  the  fact  that 
the  area  of  the  thoracic  and  right  Ijonphatic  ducts  is  very  small  as  compared  with  that 
of  all  the  IjTnphatic  vessels,  appears,  k  priori,  to  be  exceedingly  probable. 

But  an  anatomical  fact  must  be  shown  anatomically  before  it  can  be  admitted.  Now 
there  is  no  proof  of  the  communication  of  the  lymphatic  and  venous  radicles.  M.  Foh- 
mann relies  upon  certain  more  or  less  ingenious  inductions,  but  not  upon  direct  ana- 
tomical facts.  I  am,  therefore,  still  compelled  to  doubt  the  existence  of  these  commu- 
nications, and  to  class  them  with  the  vasa  serosa,  or  serous  veins  of  Haller. 

Again,  a  communication  between  the  lymphatics  and  the  veins  in  the  substance  of  the 
lymphatic  glands  had  been  conjectured  by  many  anatomists  ;  the  elder  Meckel  had  seen 
mercury,  when  thrown  into  the  lumbar  lymphatics,  pass  into  the  abdominal  veins  ;  but 
this  fact  was  attributed  to  rupture  in  the  interior  of  the  glands. — {Hewson,  Cruickskank.) 
This  apparent  communication  had  also  frequently  been  observed  by  Mascagni,  and  was 
attributed  by  him  to  rupture. 

M.  Fohmann  urges  in  reply,  that  this  communication  takes  place  under  too  slight  a 
pressure  to  be  referred  to  rupture,  that  actual  extravasations  may  be  easily  recognised, 
and  that  the  mercury  is  then  infiltrated  into  the  cellular  tissue  with  much  greater  facility 
than  it  can  enter  the  veins.  "  Why,"  he  asks,  "  supposing  the  existence  of  rupture, 
does  the  mercury  never  pass  from  the  lymphatics  into  the  arteries  1"  He  also  adduces 
in  support  of  his  opinion  a  considerable  number  of  facts,  which  show  that  injections 
thrown  into  the  lymphatic  glands  sometimes  escape  by  the  lymphatics  alone,  sometimes 
by  the  veins  alone,  and  sometimes  by  both  the  lymphatics  and  the  veins.  He  states 
that,  having  emptied  the  veins  passing  out  from  a  mesenteric  gland  in  a  horse  which  had 
been  killed  while  digestion  was  going  on,  and  having  replaced  the  intestines  in  the  ab- 
domen, he  found  some  streaks  of  chyle  in  the  veins.  Lastly,  he  has  seen,  in  birds,  the 
renal  lymphatic  vessels,  which  represent  the  l)Tmphatic  glands  in  those  animals,  opening 
directly  into  the  renal  and  sacral  veins.  M.  Lauth  has  repeated  these  experiments,  and 
obtained  the  same  results.  But,  however  imposing  the  authority  of  the  authors  just  ci- 
ted may  be,  I  must  confess  that  I  am  far  from  being  convinced,  and  that  the  facts  stated 
by  them  do  not  appear  to  me  to  be  conclusive.  I  have  made  a  great  number  of  injec- 
tions of  lymphatics,  and  in  by  far  the  greater  number  of  cases  the  mercury  passed  from 
the  afferent  into  the  efferent  lymphatic  vessels,  and  not  at  all  into  the  veins.  In  some 
cases,  it  passed  from  the  glands  into  the  veins ;  but  it  appeared  to  me  that  the  glands 
had  then  undergone  a  change  in  their  texture,  more  particularly  a  red  softening. 

It  does  not  seem  to  me,  then,  to  be  shown  that  there  is  any  direct  conununication  be- 
tween the  lymphatics  and  the  veins  within  the  substance  of  the  lymphatic  glands. 

Lippi  (of  Florence)  denies  the  communication  of  the  lymphatics  with  the  veins  within 
the  lymphatic  glands ;  but  believes  that,  besides  the  terminations  of  the  lymphatics  in 
the  venous  system  through  the  thoracic  duct  and  the  great  right  lymphatic  trunk,  there 
are  a  great  number  of  direct  communications  between  the  lymphatics  and  the  vena  por- 
tae,  the  internal  pudic  and  the  renal  veins,  and  the  vena  cava  ascendens  and  vena  azygos. 

Several  anatomists,  indeed,  had  already  met  with  lymphatic  vessels  opening  directly 
into  the  venous  system  ;  among  whom  were  Walceus,  Wepfer,  Abraham  Kaw,  Heben- 
streit,  the  elder  Meckel,  Galdani,  and  Vrolyk ;  but  the  isolated  facts  recorded  by  them 
were  regarded  by  Haller,  Mascagni,  and  Soemmering  as  anomalies,  or  as  the  results  of 
rupture. 

The  memoir  published  by  Lippi  excited  new  investigations  on  all  sides.  I  was  the 
more  inclined  to  subscribe  to  the  opinions  of  that  observer,  because,  in  1825,  I  had  most 
distinctly  seen  a  large  lymphatic  trunk  opening  directly  into  the  external  iliac  vein ;  be- 
cause it  appeared  to  me  rational  to  admit  that  the  communications  between  the  lymphatic 
and  venous  systems  would  not  be  restricted  to  the  internal  jugular  and  sub-clavian  veins ; 
because  the  communications  supposed  to  exist  by  Fohmann  and  Lauth  had  not  been  de- 
monstrated ;  because  ligature  of  the  thoracic  duct  does  not  prove  fatal  to  all  anunals 
subjected  to  that  experiment,  even  when  the  duct  is  single ;  and,  lastly,  because  the 
thoracic  duct  has  been  found  obliterated  in  many  individuals.  There  seemed,  besides,  a 
difliculty  in  admitting  that  the  thoracic  and  right  lymphatic  ducts  formed  the  termination 

Borb  other  substances.  It  is  shown  that  the  veins  are  the  absorbing-  agents  in  other  parts  of  the  body,  but  tt 
is  not  shown  that  the  lymphatics  absorb.  Some  authors  have  stated  that  the  veins  absorb  only  when  the  lym- 
phatic; system  is  diseased. 


616  ANOEIOIiOGT. 

of  the  whole  of  the  lymphatic  vessels.  It  appeared,  moreover,  at  variance  with  the  gen- 
eral laws  of  the  animal  economy  to  suppose  that  two  sets  of  organs  should  be  devoted  to 
the  same  functions ;  fbr,  if  the  veins  absorb,  the  lymphatic  system  would  seem  to  have 
no  special  use. 

Nevertheless,  truth  compels  me  to  state  that,  after  the  most  minute  and  frequent  re- 
searches which  I  have  been  able  to  make,  I  have  not  obtained  a  single  result  confirma- 
tory of  the  statements  of  M.  Lippi ;  and  that,  with  his  plates  before  me,  I  have  searched 
for  the  communications  in  all  the  points  which  he  has  indicated,  and  have  never  found 
any.  I  am,  therefore,  obliged  to  conclude,  with  MM.  Rossi,  Fohmann,  and  others,  that 
the  vessels  which  M.  Lippi  has  described  as  lymphatics  opening  into  different  parts  of 
the  venous  system  are  nothing  more  than  veins. 

Structure  of  the  Lymphatics. 

The  lymphatics,  as  well  as  the  veins,  have  two  coats.  This  structure  can  be  readUy 
shown  in  the  thoracic  duct  of  the  human  subject,  and  still  better  in  that  of  the  horse  :  the 
existence  of  these  two  coats  may  also  be  shown  by  a  method  suggested  by  Cruickshank, 
which  consists  in  turning  the  thoracic  duct  inside  out,  and  forcibly  introducing  a  tube 
into  it ;  the  lining  membrane,  which  is  then  on  the  outside,  being  less  extensible  than 
the  external  coat,  becomes  lacerated. 

The  external  coat  is  considered  to  be  fibrous  by  some,  and  muscular  by  others.  Shel- 
don says  that  he  has  distinctly  seen  muscular  fibres  arranged  circularly  around  the  tho- 
racic duct  of  the  horse.  It  appears  to  me  that  this  external  coat  resembles  the  dartoid 
tissue,  like  the  outer  coat  of  the  veins.  It  is  not  uninteresting  to  remark,  that  the  outer 
surface  of  the  lymphatics  is  often  covered  by  a  thin  layer  of  fat,  which  has  deceived  sev- 
eral anatomists. 

The  internal  coat  of  the  lymphatic  vessels  appears  to  be  of  a  serous  nature,  like  that  of 
the  veins.  Some  arterial  and  venous  twigs  ramify  in  their  parietes  ;  but  no  nerves  have 
yet  been  traced  into  them.  Minute  lymphatics  probably  arise  from  the  coats  of  the  larger 
ones.     Mascagni  believes  that  their  lining  membrane  is  entirely  lymphatic. 

Notwithstanding  their  excessive  tenuity,  the  lymphatics  are  tolerably  strong ;  less  so, 
however,  than  is  generally  stated,  for  they  are  often  lacerated  by  the  weight  of  a  small 
column  of  mercury.  They  do  not  appear  to  me  to  be  stronger  than  the  veins.  They  are 
much  less  extensible.  When  the  thoracic  duct,  or  any  other  lymphatic  vessel,  is  punc- 
tured, it  immediately  collapses,  and  forces  out  its  fluid  contents  sometimes  in  a  jet.  Some 
admit  the  existence  of  muscular  contractility  in  them.  The  vemiicular  motion  caused 
by  contraction  of  their  external  coat  is  sufficient  to  explain  the  above-named  fact.* 
The  lymphatics  are  much  more  abundantly  supplied  with  valves  than  the  veins.  The 
Fig.  224.  valves  {a  a,  Jig.  224)  are  parabolic,  and  are  arranged  in  pairs ;  they 

have  an  adherent  border  turned  towards  the  commencement,  and  a  free 
border  towards  the  termination  of  the  vessel ;  they  are  generally  sit- 
uated at  very  short  intervals  apart,  as  is  shown  by  the  knotted  ap- 
pearance of  the  vessels  (see  fig.  224),  and  occasionally  they  present 
a  circular  or  annular  arrangement,  from  which  they  have  been  re- 
garded as  true  sphincters. 

In  general,  these  valves  are  strong  enough  to  prevent  the  retrograde 
course  of  the  lymph,  and,  consequently,  of  injections  also.  Never- 
theless, Hunter  inflated  all  the  lacteals  from  the  thoracic  duct ;  Hal- 
ler  filled  all  the  lymphatics  of  the  lung  from  the  upper  part  of  the  same 
canal,  and  Marchettis  says  that  he  has  injected  the  whole  of  the  lym- 
phatics from  the  reservoir  of  Pecquet.  The  valves  are  extremely 
numerous  in  the  lymphatics  ;  they  have  sometimes  appeared  to  me 
to  be  wanting  in  the  thoracic  duct.  Like  those  of  the  veins,  the 
valves  of  the  lymphatic  vessels  appear  to  be  formed  by  a  fold  of  the 
internal  membrane. 

The  Lymphatic  Glands. 

Sylvius  was  the  first  to  distinguish  the  lymphatic  glands  under  the  term  conglobate 
glands,  from  the  glands  properly  so  called,  which  he  named  conglomerate.  Chaussier 
called  these  little  bodies  lymphatic  ganglia,  following  Soemmering,  who  first  pointed  out 
the  analogy  between  them  and  the  venous  ganglia. 

The  lymphatic  glands  are  situated  along  the  course  of  the  lymphatic  vessels,  in  refer- 
ence to  which  they  may  be  regarded  as  centres  in  which  a  certain  number  of  the  ves- 
sels open  ;  those  of  the  extremities  are  chiefly  found  at  the  upper  part  of  the  limbs  on 
the  aspect  of  flexion  ;  those  of  the  thorax,  the  abdomen,  the  head,  and  the  neck  are  pla- 
ced along  the  vertebral  column  and  the  great  vessels  ;  they  are  found  also  in  tlie  sub- 
stance of  the  mesentery,  in  the  mediastina,  at  the  roots  of  the  lungs,  &c. 

*  [The  lacteal  vessels  have  been  seen  to  underijo  a  slow  contractility  on  exposure  to  air.  or  to  the  action  of 
any  other  stimulus  ;  but  there  is  no  evidence  of  the  muscularity  of  any  part  of  the  lymphatic  system  of  mam 
malia.  In  certain  reptilia  and  amphibia  there  are  pulsating  muscular  sacs  connected  with  the  lymphatic  syi 
tern,  v?hich  are  called  lymphatic  hearts.'^ 


PREPARATION  OF  THE  LYMPHATIC  VESSELS  AND  GLANDS.  617 

Their  size  varies  from  that  of  a  millet  seed  to  that  of  a  large  filbert.  The  smallest  are 
situated  in  the  epiploon,  the  largest  at  the  roots  of  the  lungs.  They  are  often  greatly 
enlarged  by  disease.  They  are  generally  of  a  reddish-gray  colour,  excepting  at  the  root 
of  the  lungs,  when  they  are  black.  Their  form  is  irregularly  spheroidal ;  and  they  have 
been  distinctly  shown  by  Malpighi  to  have  a  cellular  structure.*  If  we  examine  with  a 
lens  a  lymphatic  gland  distended  with  fluid,  we  observe  that  it  contains  cells  ;  the  same 
fact  is  clearly  demonstrated  by  injecting  it  with  mercury,  which  shows,  moreover,  that 
the  cells  communicate  freely  with  each  other.  It  is,  nevertheless,  doubtful  whether  all 
the  cells  communicate.  The  researches  which  I  have  made  upon  this  subject  appear 
to  show  that  each  lymphatic  vessel  is  connected  with  a  distinct  portion  of  the  lymphatic 
gland  ;  and  diseases  of  the  glands  establish  the  same  fact,  by  attacking  one  part  only  of 
a  gland,  the  rest  continuing  unaffected. 

Several  l)rmphat?ic  vessels  enter  each  gland,  and  several  emerge  from  it.    Each  affer- 
ent vessel  (a  a  a,  fig.  225),  as  it  reaches  the  circumference  of  the  pig.  225. 
gland,  divides  into  a  considerable  number  of  branches,  which  diverge 
and  run  for  a  short  distance  upon  the  surface  of  the  gland,  and  then 
dip  into  its  substance.!    The  efferent  lymphatics  (i  b)  commence  in 
precisely  the  same  manner  as  the  afferent  vessels  terminate. 

The  study  of  these  vessels  in  the  larger  animals  appears  calcula- 
ted to  clear  up  all  doubts  as  to  the  structure  of  the  lymphatic  glands. 
Abernethy  having  injected  the  mesenteric  arteries  and  veins  of  a 
whale,  saw  the  fluid  run  into  pouches  about  the  size  of  an  orange  ; 
he  then  injected  mercury  into  the  lacteals,  and  found  that  it  flowed 
into  the  same  cavities ;  he  therefore  concluded  that  the  arteries, 
veins,  and  lacteals  all  opened  into  the  same  cavities.  This  fact  ap- 
pears to  confirm  the  observations  quoted  by  MM.  Fohmann  and  Lauth, 
relative  to  the  communications  of  the  lymphatics  with  the  veins 
within  the  substance  of  the  glands  ;  but  the  objections  already  urged 
against  those  observations  will  apply  to  this  one  also. 

The  lymphatic  glands  are  enclosed  in  a  fibrous  membrane  ;  I  have 
in  vain  attempted  to  find  the  fleshy  coat  described  by  Malpighi,  and  which  he  imagined 
sent  prolongations  into  the  substance  of  these  glands. 

The  lymphatic  glands  are  supplied  with  very  large  arteries  for  their  size,  and  they 
give  off  still  larger  veins  :  a  proper  tissue  {d)  appears  to  enter  into  their  composition. 

The  lymphatic  glands  may  be  said  to  consist  essentially  of  an  inextricable  interlace- 
ment of  lymphatic  vessels,  their  structure  having  some  analogy  to  that  of  the  corpus 
cavernosum  penis,  and  to  that  of  the  spleen.  This  opinion  is  confirmed  by  reference  to 
the  anatomy  of  birds,  in  which  lymphatic  glands  exist  only  in  the  neck,  their  place  being 
supplied  by  plexuses  in  all  other  parts. 

Preparation  of  the  Lymphatic  Vessels  and  Glands. 

I  have  already  said,  that  in  order  to  inject  the  network  of  lymphatics,  the  pipe  should 
be  very  superficially  introduced  into  the  free  cutaneous,  serous,  or  mucous  surfaces. 
When  the  injection  is  successful,  the  mercury  passes  from  this  network  into  the  vessels 
which  emerge  from  it,  reaches  as  far  as  the  l3anphatic  glands,  and  even  penetrates  through 
several  series  of  them. 

The  great  number  and  peculiar  arrangement  of  the  valves  prevents  the  injection  of  the 
lymphatics  from  the  centre  towards  the  extremities ;  I  have  attempted  to  do  this  several 
times,  without  success,  by  introducing  the  tube  into  the  thoracic  duct. 

From  the  small  caliber  of  the  lymphatics,  it  is  necessary  to  use  a  capillary  tube  for 
these  injections.  Mercury,  notwithstanding  the  inconvenience  of  its  fluidity,  and  in- 
capability of  being  made  solid,  is  the  most  convenient  material  for  the  purpose  ;  the 
weight  of  a  column  of  mercury  about  fifteen  or  eighteen  inches  in  height  aflJbrds  suffi- 
cient power  for  the  injection.  Anel's  syringe  is  well  adapted  for  injecting  the  thoracic 
duct,  which  may  be  filled  with  a  solution  of  isinglass,  or,  still  better,  with  milk,  which  be- 
comes coagulated  by  the  alcohol.  The  best  apparatus  for  injecting  the  lymphatics  is  a 
glass  cylinder,  to  the  lower  end  of  which  is  adapted  a  flexible  tube,  which  is  terminated 
by  a  metal  pipe,  provided  with  a  stopcock,  and  supporting  a  capillary  tube  of  glass,  which 
is  better  than  one  made  of  steel  or  platinum,  like  those  generally  used  in  Germany.  A 
ring  is  attached  to  the  upper  end  of  the  glass  tube,  by  means  of  which  the  apparatus  may 
be  suspended  :  this  greatly  facilitates  the  employment  of  the  apparatus. 

In  order  to  inject  the  lymphatics,  one  of  these  vessels  should  be  exposed  at  a  greater 
or  less  distance  from  the  centre  ;  for  example,  in  the  lower  extremity,  upon  either  the 
internal  or  external  malleolus,  or,  what  is  still  better,  over  the  metatarso-phalangal  artic- 
ulations, in  the  way  practised  by  Mascagni ;  the  vessel  must  then  be  punctured,  and 
the  tube  introduced  into  its  interior ;  the  stopcock  is  then  opened,  and  the  mercury  run? 

*  See  note,  infra. 

t  [Within  the  gland  the  lymphatics  form  a  dense  network  (c) ;  when  the  vessels  of  which  this  network  ia 
composed  are  distended,  they  give  the  cellular  appearance  to  a  section  of  the  g-land  noticed  by  Malpighi. 
Cruickshank,  <&c.] 

41 


'IBI'8  ANGEIOLOGY. 

as  far  as  the  gland  into  which  the  vessels  opens,  and  at  the  same  time  enters  all  the 
vessels  which  anastomose  either  directly  or  indirectly  with  the  one  into  which  the  tube 
IS  introduced.  The  vasa  efferentia  are  also  soon  injected,  and  if  the  experiment  be  con- 
tinued long  enough,  the  mercury  will,  in  all  probability,  reach  the  thoracic  duct  if  no 
rupture  should  occur.  The  internal  jugular,  sub-clavian,  and  brachio-cephalic  veins  of 
both  sides  of  the  body  may  be  previously  injected,  in  order  to  prevent  the  mercury  enter- 
ing these  vessels  by  the  thoracic  duct  and  its  supplemental  canals. 

We  may  also  have  recourse  to  the  following  method,  on  account  of  its  greater  facility  . 
Puncture  a  lymphatic  gland  with  a  capillary  tube  ;  all  the  efferent  vessels  which  com- 
municate with  the  cells  thus  punctured,  and  all  the  other  portions  of  the  lymphatic  sys- 
tem which  communicate  with  those  vessels,  will  thus  be  injected.  But  this  method  is 
manifestly  defective. 

With  regard  to  the  choice  of  subjects,  it  may  be  remarked  that  the  lymphatics  are 
much  more  easily  seen  when  the  cellular  tissue  is  moderately  infiltrated  than  when  there 
is  extreme  emaciation.  Fat  subjects  are  the  worst  of  all :  adults  are  preferable  to  chil- 
dren and  old  subjects. 

In  describing  the  lymphatics,  I  shall  follow  the  same  arrangement  as  Mascagni,  with 
some  slight  modifications.  Thus,  after  having  described  the  thoracic  duct  and  the  great 
right  lymphatic  trunk,  I  shall  notice  in  succession  all  the  lymphatic  vessels  which  enter 
it,  beginning  with  those  of  the  lower  extremities.  I  shall  not  describe  the  vessels  and 
glands  separately,  but  I  shall  group  the  vessels  around  the  glands,  as  around  central 
points  towards  which  they  all  converge. 


DESCRIPTION  OF  THE  LYMPHATIC  SYSTEM. 
The  Thoracic  Duct — the  Right  Thoracic  Duct. — The  Lymphatic  System  of  the  Lower  Ex- 
tremity— of  the  Pelvic  and,  Lumbar  Regions — of  the  Liver — of  the  Stomach,  Spleen,  and 
Pancreas — of  the  Intestines — of  the  Thorax — of  the  Head — of  the  Cervical  Regions — of  the 
Upper  Extremity  and  Upper  Part  of  the  Trunk. 

The  Thohacic  Duct. 

Dissection. — The  thoracic  duct  may  be  examined,  when  distended  with  chyle,  in  an 
animal  killed  during  the  process  of  digestion.  If  it  is  to  be  injected  in  the  human  sub- 
ject, turn  the  intestines  to  the  left  and  the  liver  to  the  right ;  seek  for  the  reservoir  of 
Pecquet  (receptaculum  chyli)  between  the  aorta  and  the  right  crus  of  the  diaphragm  ;  fol- 
low one  of  the  lymphatic  trunks  leading  from  this  reservoir  to  the  lumbar  glands,  and 
puncture  it  with  the  injecting  tube.  Care  must  be  taken  to  tie  the  left  sub-clavian  vein 
both  on  the  inside  and  on  the  outside  of  the  termination  of  the  internal  jugular  vein  ;  or, 
still  better,  first  fill  the  sub-clavian  and  internal  jugular  veins  with  a  solid  injection.  If 
we  wish  to  make  a  preparation  to  be  preserved,  it  is  much  better  to  inject  the  thoracic 
duct  with  isinglass  size  by  an  Anel's  syringe  than  to  use  mercury. 

The  thoracic  duct  {s  1 1  u,  fig.  223),  so  called  from  its  situation,  is  the  common  trunk 
of  all  the  lymphatics  of  the  human  body,  excepting  those  of  the  right  side  of  the  head, 
neck,  and  thorax,  and  of  the  right  upper  extremity. 

It  commences  opposite  the  second  lumbar  vertebra,  by  the  junction  of  a  variable  num- 
ber of  branches  :  Meckel  says  there  are  three,  but  I  have  generally  found  five  or  six. 
These  vessels,  which  are  usually  of  large  size,  pass  out  from  the  abdominal  lymphatic 
glands  ;  they  all  converge  towards  a  dilatation  or  ampulla  of  a  triangular  shape,  which 
is  called  the  reservoir  or  cistern  of  Pecquet  (cisterna,  receptaculum  chyli,  s,  fig.  223),  after 
the  anatomist  who  showed  that  the  lacteals  did  not  pass  to  the  liver,  as  was  generally  be- 
lieved, in  accordance  with  the  opinion  of  Aselli,  but  that  they  entered  the  thoracic  duct. 

This  ampulla,  which  is  often  nothing  more  than  the  point  at  which  the  lymphatic  ves- 
sels meet,  and  presents  no  dilatation,  is  situated  to  the  right  of  and  behind  the  aorta, 
immediately  below  the  aortic  opening  in  the  diaphragm,  and  by  the  side  of  the  right  eras 
of  that  muscle. 

Having  commenced  thus,  the  thoracic  duct  passes  verticaUy  upward,  enters  the  tho- 
rax through  the  aortic  opening  in  the  diaphragm,  and  becomes  situated  in  the  posterior 
mediastinum  {t  t),  in  front  of  the  vertebral  coliunn,  a  little  to  the  right  of  the  median 
Jine,  and  has  the  vena  azygos  (a  a')  on  its  right  side,  and  the  aorta  on  its  left.  Having 
reached  the  front  of  the  fourth  dorsal  vertebra,  it  inclines  towards  the  left,  still  continu- 
ing to  ascend,  passes  behind  the  aorta,  gains  the  left  side  of  the  oesophagus,  runs  along 
oehind  and  on  the  inner  side  of  the  left  sub-clavian  artery,  and  escapes  through  the  su- 
perior opening  of  the  thorax ;  having  arrived  behind  the  left  internal  jugular  vein,  and 
in  front  of  the  seventh  cervical  vertebra,  it  immediately  bends  forward,  so  as  to  form  an 
arch  (m)  like  that  of  the  aorta,  and  finally  opens  into  the  angle  formed  by  the  junction  of 
the  left  internal  jugular  and  sub-clavian  veins,  or  sometimes  into  the  sub-clavian  vein 
externally  to  that  angle.  The  direction  of  the  thoracic  duct  is  not  straight,  but  flexu- 
ous  :  its  windings  are  sometimes  very  mmierous. 

From  the  relations  of  the  thoracic  duct  while  within  the  posterior  mediastinum,  it  fol- 


THE   RIGHT    THORACIC   DUCT,    ETC.  ^'Wfe 

lows  that,  in  order  to  expose  its  lower  portion,  it  must  be  sought  for  on  the  right  side 
of  that  cavity,  and  that  we  must  look  for  its  upper  portion  on  the  left  side,  and  must  di- 
vide the  left  layer  of  the  mediastinum  in  order  to  expose  it. 

The  thoracic  duct  terminates  in  many  different  ways :  thus,  it  not  unfrequently  opens 
by  several  trunks  into  the  left  internal  jugular  and  sub-clavian  veins.  A  still  more  fre- 
quent method  of  termination,  and  one  which  it  is  extremely  important  to  know,  is  that 
in  which  the  duct,  at  its  upper  part,  is  divided  into  two  branches,  the  left  one  of  which 
(m)  is  distributed  in  the  usual  manner,  while  the  right  (indicated  by  a  smaller  letter  «) 
opens  into  the  right  sub-clavian  vein  in  connexion  with  the  great  lymphatic  duct  of  the 
right  side. 

The  caliber  of  the  thoracic  duct  is  not  at  all  proportioned  to  the  number  and  size  of 
the  lymphatics  which  terminate  in  it.  Sometimes,  in  fact,  lymphatics  are  found  which, 
when  distended,  are  as  large  as  a  goose-quill.  Still  less  is  it  proportioned  to  all  the 
lymphatics  of  the  body,  of  which  it  is  regarded  as  the  common  trunk.  Its  caliber  is  even 
smaller  than  that  acquired  by  some  lymphatics  under  many  circumstances  ;  for  exam- 
ple, by  those  of  the  uterus  during  pregnancy  :  this  is  a  powerful  argument  in  favour  of 
those  who  regard  the  thoracic  duct  as  by  no  means  corresponding  to  all  the  lymphatics 
of  the  human  body. 

The  thoracic  duct  is  not  of  uniform  caliber  in  its  entire  length.  It  commences  by  a 
dilatation  of  two  or  three  lines  in  diameter ;  in  the  middle  of  the  thorax  it  becomes  con- 
tracted to  less  than  two  lines  in  diameter,  and  it  is  again  dilated  a  little  at  the  arch 
which  it  forms  before  its  termination. 

The  thoracic  duct  not  unfrequently  divides,  during  its  course,  into  several  branches, 
which  form  a  sort  of  network ;  it  often  subdivides  into  two  branches  of  unequal  size, 
which  unite  again  after  a  variable  distance. 

The  thoracic  duct  receives,  while  in  the  thorax,  a  very  large  trunk,  which  is  derived 
from  the  liver,  and  perforates  the  diaphragm  through  a  special  opening.  I  have  seen  this 
trunk  cross  and  continue  in  front  of  the  thoracic  duct,  being  equal  to  it  in  size,  and  at 
last  enter  it  opposite  the  fifth  dorsal  vertebra. 

The  thoracic  duct  has  been  observed  to  end  on  the  right  side,  and  then  the  lymphat- 
ics of  the  left  side  of  the  head,  left  upper  extremity,  left  lung,  and  left  side  of  the  heart, 
entered  separately  into  the  sub-clavian  vein  of  the  corresponding  side.  Meckel  has  cor- 
rectly observed,  that  such  a  disposition  is  a  first  trace  of  the  lateral  transposition  of  the 
viscera. 

Valves. — Of  all  parts  of  the  lymphatic  system,  the  thoracic  duct  has  the  fewest  and 
the  smallest  valves.  The  most  remarkable  are  those  situated  at  its  termination  in  the 
sub-clavian  vein ;  their  free  borders  are  turned  towards  the  vein,  so  that  they  oppose 
any  influx  of  the  venous  blood  into  the  thoracic  duct.  The  free  borders  of  the  other 
valves,  when  they  exist,  are  turned  upward,  their  convex  borders  being  directed  down- 
ward :  the  course  of  the  fluid  within  the  duct  is,  therefore,  from  below  upward. 

The  Right  Thoracic  Duct. 

The  great  right  lymphaiic  duct,  or  right  thoracic  duct,  is  a  large  vessel,  the  common 
trunk  of  all  the  lymphatics  derived  from  the  right  half  of  the  head  and  neck,  the  right 
upper  extremity,  the  right  lung,  the  right  side  of  the  heart,  and  often,  also,  of  those  from 
the  right  half  of  the  diaphragm  and  of  the  liver.  This  trunk  (v,  fig.  223),  which  is  not 
more  than  an  inch  long,  resembles  the  curved  portion  of  the  thoracic  duct ;  it  opens  at 
the  angle  formed  by  the  junction  of  the  right  internal  jugular  and  sub-clavian  veins. 

Sometimes  this  common  trunk  does  not  exist,  and  then  the  lymphatics,  by  the  junc- 
tion of  which  it  is  usually  formed,  enter  the  veins  separately.  Anastomoses  always  ex- 
ist, moreover,  between  the  left  and  right  thoracic  ducts. 

The  Lymphatic  System  of  the  Lower  Extremity. 

The  Lymphatic  Glands  of  the  Lower  Extremity. 

Tlie  lymphatic  glands  of  the  lower  extremity  are  the  anterior  tibial  gland,  the  popliteal 
gland,  and  the  inguinal  glands. 

The  anterior  tibial  gland  is  situated  at  a  variable  height  in  front  of  the  interosseous 
ligament,  generally  at  its  upper  part.  Hewson  has  seen  it  below  the  middle  :  Meckel 
has  found  two  glands  here  ;  but  the  existence  even  of  one  gland  is  not  constant. 

The  popliteal  glands  are  four  in  number ;  one  of  them  is  situated  immediately  beneath 
the  fascia ;  the  other  three  are  placed  deeply  at  variable  heights  along  the  vessels  of  the 
popliteal  space  :  they  are  rather  small. 

The  inguinal  glands  are  the  most  numerous  and  important ;  they  are  situated  in  the 
fold  of  the  groin,  below  Poupart's  ligament,  and  are  generally  grouped  around  the  en- 
trance of  the  internal  saphenous  into  the  femoral  vein,  in  a  sort  of  depression  formed 
between  the  adductor  longus  and  pectineus  on  the  inside,  and  the  psoas  and  iliacus  on 
the  outside.  They  are  not  unfrequently  continued  along  the  internal  saphenous  vein  as 
low  down  as  the  middle  of  the  thigh.  They  are  divided  into  superficial  and  deep.  The 
latter  are  very  variable  in  size  and  number,  and  are  often  wanting :  they  are  sometimes 


620  ANGEIOLOGY. 

continuous  with  the  superficial,  through  the  saphenous  opening  in  the  fascia  lata.  Thff 
number  of  the  superficial  glands  also  varies  much :  it  is  nearly  always  inversely  propor- 
tioned to  the  size  of  the  glands,  which  is  also  subject  to  great  variety  in  diflferent  indi- 
viduals and  at  different  ages.  There  can  be  no  doubt  that  these  differences  in  number 
and  in  size  depend,  ceteris  paribus,  no  less  upon  actual  differences  than  upon  the  subdivis- 
ion of  one  gland  into  several,  or,  rather,  upon  the  union  of  a  certain  number  of  glands 
into  one.  Sometimes  we  find  a  large  circular  gland  situated  around  the  termination  of 
the  saphenous  vein.  The  inguinal  glands,  moreover,  are  placed  at  different  depths  in 
the  substance  of  the  fibrous  layers  which  constitute  the  superficial  fascia.  Several  of 
these  glands  are  frequently  united  to  each  other,  not  only  by  lymphatic  vessels,  but  also 
by  prolongations  of  their  proper  substance. 

The  Lymphatic  Vessels  which  enter  the  Lymphatic  Glands  of  the  Lower  Ex- 
tremity. 

Preparation. — Introduce  the  pipe  into  some  of  the  lymphatic  vessels  between  the  toes, 
over  the  metatarso-phalangal  articulations.  Mascagni  employed  this  method,  which  is 
as  easy  as  introducing  the  pipe  into  the  vessels  which  run  between  the  internal  malleo- 
lus and  the  skin.  A  still  better  method  of  injection,  when  it  proves  successful,  is  to  fill 
the  lymphatic  network  in  the  skin  by  introducing  the  pipe  into  the  dermis  at  any  point 
beneath  the  cuticle.  But  the  limb  requires  to  be  warmed  for  this  injection  to  succeed. 
I  have  made  a  very  beautiful  preparation  by  injecting  the  cutaneous  network  of  lymphat- 
ics upon  the  sole  of  the  foot  in  a  new-born  infant.  The  mercury  ran  as  far  as  the  glands 
situated  along  the  iliac  vessels. 

If  the  pipe  be  inserted  into  the  skin  upon  the  scrotum,  or  into  the  mucous  membrane 
covering  the  glans  penis  in  the  male,  or  into  the  skin  of  the  labia  majora  in  the  female, 
the  mercury  will  reach  the  lymphatic  glands  of  the  groin. 

The  lymphatics  which  ramify  in  the  gluteal  region,  and  those  situated  in  the  sub-cu- 
taneous cellular  tissue  of  the  abdominal  parietes,  may  be  injected  in  the  same  manner. 

The  deep  lymphatics  of  the  leg  open  into  the  anterior  tibial  gland  and  popliteal  glands. 
All  the  superficial  lymphatics  of  the  lower  extremity,  and  also  those  of  the  gluteal  re- 
gion, perineum,  external  genital  organs,  and  sub-umbilical  portion  of  the  parietes  of  the 
abdomen,  terminate  in  the  inguinal  glands. 

Lymphatics  of  the  Lower  Extremities. — The  lymphatics  of  the  lower  extremities,  like 
the  veins,  are  divided  into  superficial  and  deep. 

The  deep-seated  lymphatics  are  fewer  in  number  and  less  accurately  known  than  the 
superficial ;  they  accompany  the  deep-seated  bloodvessels.  It  is  probable  that  every  ar- 
terial and  venous  branch  has  its  corresponding  lymphatics  ;  but  those  only  which  ac- 
company the  great  vessels  have  been  as  yet  discovered.  They  are  divided  into  the  pe- 
roneal, the  anterior  and  posterior  tibial,  and  the  femoral. 

Of  the  anterior  tibial  lymphatics,  two  only  have  been  demonstrated,  although  their  num 
ber  must  certainly  be  greater.  One  of  these  accompanies  the  plantar  arch,  the  dorsal 
artery  and  vein  of  the  foot,  and  the  anterior  tibial  vessels  ;  it  communicates  with  the 
posterior  tibial  and  the  peroneal  lymphatics,  opposite  the  upper  part  of  the  interosseous 
ligament,  and  enters  the  anterior  tibial  gland,  or  more  frequently  perforates  the  interos- 
seous ligament,  and  enters  the  popliteal  glands. 

The  other  anterior  tibial  lymphatic  arises  deeply  from  the  outer  side  of  the  foot,  and 
joins  the  preceding. 

The  posterior  tibial  lymphatics,  two  or  three  in  number,  and  likewise  the  peroneal  lymphat- 
ics, sometimes  unite  into  a  single  trunk,  and  enter  the  popliteal  glands. 

The  branches  which  emerge  from  the  popliteal  glands,  five  or  six  in  number,  traverse 
the  opening  in  the  adductor  muscle,  ascend  along  the  femoral  vein,  and  open  into  the 
deep  inguinal  glands. 

The  superficial  lymphatics,  which  can  be  very  easily  shown  to  arise  from  a  network  in 
the  skin,  run  upward  and  inward,  to  reach  the  inner  side  of  the  leg,  and  then  pass  be- 
hind the  internal  condyle  of  the  femur :  those  which  arise  from  the  outer  side  of  the  foot 
and  leg,  after  ascending  vertically  in  front  of  the  muscles  of  the  anterior  region  of  the 
leg,  cross  over  the  upper  part  of  the  tibia  obliquely  from  without  inward,  so  that  all  the 
superficial  lymphatics  at  last  gain  the  inner  and  back  part  of  the  internal  condyle  of  the 
femur  :  from  this  point  they  incline  forward  like  the  sartorius,  upon  which  they  are  pla- 
ced, and  then  pass  vertically  upward,  and  are  distributed  to  the  different  lymphatic  glands 
of  the  groin. 

A  certain  number  of  lymphatic  vessels  which  commence  upon  the  outer  border  of 
the  foot  (there  are  not  more  than  two  or  three)  pass  over  the  external  malleolus  tc 
reach  the  external  saphenous  vein,  become  sub-aponeurotic  like  that  vein,  and  enter  the 
most  superficial  of  the  popliteal  glands.  These  lymphatics,  which  accompany  the  exter- 
nal saphenous  vein,  are  regarded  by  some  authors  as  forming  part  of  the  deep  set  o* 
vessels. 

Superficial  Lymphatics  of  the  External  Genital  Organs,  Gluteal  Region,  Perineum,  and 


THE    PELVIC    AND   LUMBAR    LYMPHATIC    GLARDS.  621 

Lower  Part  of  the  Abdomen. — The  superficial  lymphatic  vessels  from  these  parts  also  en- 
ter the  inguinal  glands. 

The  superficial  lymphatics  of  the  external  genital  organs  of  the  male  are  divided  into  those 
of  the  scrotum  and  those  of  the  penis.  If  the  skin  of  the  scrotum  be  injected,  several 
8ub-cutaneous  branches  will  be  seen  to  pass  from  the  network  beneath  the  epidermis 
upward  along  the  sides  of  the  penis,  and  then,  after  describing  a  curve  with  the  concav- 
ity directed  downward,  to  open  into  the  inguinal  glands,  generally  into  those  which  are 
nearest  the  middle  line,  but  I  have  seen  them  pass  to  the  glands  surrounding  the  saphe- 
nous opening.  If  we  inject  the  skin  of  the  penis,  and  more  especially  the  membrane 
covering  the  glans,  the  mercury  penetrates  into  the  dorsal  lymphatics  of  the  penis,  and 
reaches  the  innermost  and  highest  of  the  inguinal  glands.  The  injection  from  the  skin 
of  the  penis  enters  the  superficial  lymphatics ;  the  injection  from  the  membrane  cover- 
ing the  glans  enters  only  those  superficial  lymphatics  which  accompany  the  dorsal  blood- 
vessels of  the  penis. 

In  the  female,  injections  of  the  skin  of  the  labia  majora,  and  of  the  mucous  membrane 
of  the  labia  majora,  labia  minora,  and  clitoris,  yield  similar  results  as  the  injection  of 
the  scrotum  and  penis  in  the  male.  We  know  that  diseases  of  the  labia,  nymphai,  and 
clitoris,  like  those  of  the  prepuce,  penis,  and  scrotum,  occasion  enlargement  of  the  in- 
guinal lymphatic  glands. 

The  lymphatics  of  the  perineum  unite  with  the  preceding,  and  with  the  lymphatics  of  the 
lower  extremities. 

The  superficial  lymphatics  of  the  gluteal  region  turn  horizontally  round  the  glutaeus  max- 
imus  and  medius,  and  enter  the  external  and  middle  lymphatic  glands  of  the  groin.  This 
is  the  reason  why  furunculi  or  other  diseases  of  the  skin  upon  the  nates  may  give  rise 
to  enlargement  of  the  inguinal  glands. 

The  superficial  lumbar  lymphatics,  as  well  as  those  of  the  sub-umiilical  portion  of  the 
abdominal  parietes,  have  a  descending  course  :  those  of  the  loins  run  forward  and  down- 
ward, those  of  the  abdomen  vertically  downward ;  they  both  terminate  in  the  outermost 
and  highest  of  the  inguinal  glands  ;  and  hence  diseases  of  the  skin  covering  the  lumbar 
and  sub-umbilical  regions  may  occasion  swelling  of  the  inguinal  glands. 

The  lymphatic  vessels  which  accompany  the  epigastric  and  circumflex  iliac  veins  also 
enter  the  glands  of  the  groin. 

The  Lymphatic  System  of  the  Pelvic  and  Lumbar  Regions. 
The  Pelvic  and  Lumbar  Lymphatic  Glands. 

The  lymphatic  glands  of  the  pelvis  are  divided  into  the  external  iliac,  the  internal  iliac, 
and  the  sacral. 

The  external  iliac  lymphatic  glands,  irregular  in  number,  are  situated  along  the  artery 
of  that  name.  Three  of  them  require  to  be  particularly  noticed ;  they  are  situated  im- 
mediately behind  the  femoral  arch,  one  of  them  on  the  outer  side,  another  in  front,  and 
the  third  on  the  inner  side  of  the  external  iliac  vessels.  It  is  important,  in  reference  to 
the  ligature  of  the  external  iliac  artery,  to  know  that  these  lymphatic  glands  are  subject 
to  enlargement. 

The  internal  iliac  lymphatic  glands  occupy  the  space  between  the  external  and  internal 
iliac  vessels.  The  bladder  has  proper  lymphatic  glands  situated  upon  its  posterior  sur- 
face, and  near  its  summit.  In  the  female,  some  of  the  pelvic  lymphatic  glands  may  be 
regarded  as  belonging  to  the  vagina  and  uterus.  One  tolerably  large  gland,  which  may 
be  said  to  be  constant,  occupies  the  internal  orifice  of  the  obturator  canal,  and  I  have 
often  found  it  inflamed  or  indurated  in  diseases  of  the  uterus. 

The  sacral  lymphatic  glands  occupy  the  sides  of  the  anterior  surface  of  the  sacrum  : 
several  of  them  are  situated  within  the  folds  of  the  meso-rectum,  and  belong  to  the  rec- 
tum itself 

The  lumbar  or  aortic  lymphatic  glands  are  very  numerous,  and  form  a  continuous  chain 
with  the  pelvic  glands  ;  they  occupy  the  angular  interval  between  the  conunon  iliac  ar- 
teries, being  placed  along  those  arteries  themselves,  and  also  surround  the  aorta  and  the 
ascending  vena  cava,  but  more  particularly  the  aorta.  It  is  important  to  note  the  rela- 
tion of  these  lymphatic  glands  with  the  aorta,  for  that  vessel  is  sometimes  found  much 
compressed  and  narrowed  from  enlargements  of  these  glands  by  tubercular  or  cancerous 
deposite. 

There  is  also  a  lymphatic  gland  in  each  intef-transverse  space  on  both  sides  of  the 
lumbar  region  ;  so  that  the  lumbar  lymphatic  glands  may  be  divided  into  the  median  and 
the  lateral. 

The  Lymphatic  Vessels  which  enter  the  Pelvic  and  Lumbar  Lymphatic  Glands. 
The  different  lymphatic  vessels  which  proceed  from  the  inguinal  glands  enter  the  pel- 
vis behind  the  femoral  arch,  and  near  the  femoral  vein.  The  foramina  through  which 
they  pass  are  so  numerous,  that  the  fascia  which  is  perforated  by  them  is  named  the 
cribriform  fascia.     Having  arrived  beneath  the  peritoneum,  they  are  divided  into  two 


633'  ANGEIOLOGY. 

sets,  one  of  which  descends  into  the  cavity  of  the  pelvis,  and  tenninates  in  the  several 
internal  iliac  lymphatic  glands  ;  while  the  other  enters  the  external  iliac  glands,  and 
more  particularly  those  situated  behind  the  femoral  arch.  These  external  iliac  glands, 
moreover,  are  joined  by  the  epigastric  lymphatics,  some  of  which  enter  the  inguinal  glands, 
and  by  the  ilio-lumbar  lymphatics. 

The  lymphatic  glands  of  the  pelvis  also  receive  the  deep  lymphatics  of  the  nates,  which 
accompany  the  gluteal  and  sciatic  arteries  ;  the  lymphatics  corresponding  with  the  ob- 
turator vessels  ;  the  lymphatics  of  the  bladder  and  lower  end  of  the  rectum,  those  of  the 
prostate  and  vesiculse  seminales,  and  the  deep  lymphatics  of  the  penis  in  the  male,  and 
those  of  the  vagina,  clitoris,  and  neck  of  the  uterus,  in  the  female.  The  lymphatics  of 
the  bladder,  before  entering  the  pelvic  glands,  traverse  the  glands  proper  to  itself :  the 
greater  number  of  the  lymphatics  of  the  bladder  run  beneath  the  peritoneum  upon  its 
posterior  surface.  I  have  seen  the  vesical  lymphatics  filled  with  pus.  Some  other 
lymphatics  emerging  from  the  internal  iliac  glands  accompany  the  external  and  internal 
iliac  arteries  and  veins,  ascend  in  front  of  the  sacrum,  pass  through  other  lymphatic 
glands,  and  arrive  at  the  brim  of  the  pelvis.  At  this  point,  the  lymphatics  of  the  right  and 
left  sides  unite  together.  These  vessels  pass  through  one  or  several  series  of  lumbar 
lymphatic  glands,  and  at  last  open  into  the  thoracic  duct.  This  collection  of  lymphatic 
vessels  and  glands  forms  the  internal  and  external  iliac  lymphatic  plexuses.  The  inter- 
nal iliac  lymphatic  plexus  is  placed  in  the  cavity  of  the  pelvis,  and  surrounds  the  inter- 
nal iliac  vessels  :  the  external  iliac  lymphatic  plexus  is  situated  along  the  vessels  of  that 
name. 

All  the  lymphatics  of  the  lower  extremities,  after  having  passed  through  a  greater  oj 
less  number  of  glands,  open  at  last  into  these  lumbar  glands,  so  that  the  vessels  and 
glands  together  may  be  said  to  form  an  uninterrupted  chain.  Thus,  passing  from  plex- 
us to  plexus,  and  from  gland  to  gland,  the  lymphatics  of  even  the  most  distant  parts  ar- 
rive, at  length,  at  the  thoracic  duct. 

The  lateral  lumbar  lymphatic  glands,  viz.,  those  which  occupy  the  spaces  between  the 
transverse  processes  of  the  lumbar  vertebrae,  receive  the  lumbar  lymphatics,  properly  so 
called,  which  correspond  to  the  bloodvessels  of  that  name.  From  these  glands,  commu- 
nicating vessels  pass  to  the  aortic  lumbar  glands.  The  collection  of  lymphatic  vessels 
and  glands  occupying  the  lumbar  region  is  called  the  lumbar  lymphatic  plexus.  The 
following  lymphatic  vessels  also  enter  directly  into  the  lumbar  glands  :  the  lymphatics 
of  the  testicles  in  the  male  ;  the  lymphatics  of  the  ovaries  and  Fallopion  tubes,  and  also 
of  the  body  and  upper  part  of  the  neck  of  the  uterus,  in  the  female  ;  and  the  lymphatics 
of  the  kidneys  in  both  sexes. 

The  Lymphatics  of  the  Testicle. — It  has  been  already  stated  that  the  lymphatics  of  the 
covering  of  the  testicle  enter  the  superficial  inguinal  glands  ;  those  which  belong  to  the 
gland  itself  are  divided  into  the  superficial  and  deep.  The  superficial  lymphatics  may  be 
injected  with  the  greatest  facility  by  puncturing  the  serous  membrane  covering  the  tu- 
nica albuginea ;  the  tunica  vaginalis  will  then  appear  as  if  covered  with  a  coat  of  silver. 
(See  the  beautiful  plates  of  Panizza.)  These  superficial  vessels  have  numerous  commu- 
nications with  the  deep-seated  lymphatics,  so  that  both  sets  are  injected  at  the  same 
time.  All  the  lymphatics  from  the  epididymus  and  the  body  of  the  testicle,  which  are 
very  numerous  and  large,  ascend  with  and  assist  in  forming  the  spermatic  cord,  pass 
through  the  inguinal  canal,  follow  the  course  of  the  spermatic  vessels,  and  enter  the 
lumbar  lymphatic  glands. 

The  Lymphatics  of  the  Uterus. — Having,  in  diseases  of  the  uterus  incidental  to  the  pu- 
erperal state,  frequently  detected  pus  in  the  lymphatics  of  the  uterus  (vide  Anat.  Path., 
liv.  xiii.,  pi.  1,  2,  3),  I  have  been  able  to  trace  the  exact  distribution  of  these  vessels,  and 
would  divide  them  into  superficial  and  deep.  The  superficial  lymphatics  are  situated  im- 
mediately under  the  peritoneum  ;  the  deep  lymphatics  form  several  successive  layers, 
which  occupy  different  planes  within  the  substance  of  the  uterus.  The  IjTnphatics  near 
the  neck  of  this  organ  enter  the  pelvic  and  sacral  lymphatic  glands.  A  certain  number 
of  the  uterine  lymphatics  enter  a  lymphatic  gland  situated  at  the  internal  orifice  of  the 
obturator  canal. 

All  the  uterine  IjTnphatics,  excepting  those  near  the  neck  of  that  organ,  pass  towards 
the  sides  and  upper  border  of  the  uterus  ;  some  run  within  the  substance  of  the  broad  lig- 
aments, and  they  all  reach  the  upper  or  tubal  angles  of  the  viscus.  They  are  joined  by 
the  lymphatics  of  the  ovaries,  broad  ligaments,  and  Fallopian  tubes,  and  then  ascend  in 
front  of  the  corresponding  ovarian  artery  and  veins.  Having  arrived  in  front  of  the  lower 
part  of  the  kidneys,  they  incline  towards  the  middle  line,  and  enter  the  glands  which  are 
situated  in  front  of  the  vena  cava  and  aorta.  Without  having  witnessed  it,  it  is  impos- 
sible to  form  any  idea  of  the  enormous  size  which  the  uterine  lymphatics  may  acquire 
during  pregnancy :  several  of  these  vessels,  when  filled  with  pus,  become  so  dilated  that 
one  would  at  first  sight  believe  that  an  abscess  had  been  formed. 

The  Lymphatics  of  the  Kidneys  and  Supra-renal  Capsules. — These  are  divided  into  super- 
ficial and  deep.  The  superficial  lymphatics  have  never  been  injected  directly  ;  but  if  a 
fine  injection  be  thrown  into  the  renal  arteries  and  veins,  the  injection,  freed  from  col- 


THE    LYMPHATICS    Of   THE    LIVER.  623 

ouring  matter,  passes  into  the  lymphatics.  This  was  the  only  way  in  which  Mascagni 
could  inject  the  superficial  lymphatics  of  the  kidney,  which  he  has  represented  in  his 
beautiful  plates. 

The  deep  lymphatics,  which  are  very  numerous,  pass  out  of  the  fissure  of  the  kidney, 
and  enter  the  glands  in  front  of  and  behind  the  aorta  and  vena  cava. 

The  lymphatics  of  the  supra-renal  capsules  are  remarkable  for  their  size  and  number  ; 
they  unite  with  those  of  the  kidneys,  and  terminate  in  the  same  manner. 

The  Lymphatic  System  of  the  Liver. 
Preparation. — Of  all  the  lymphatic  vessels,  those  of  the  liver  are  the  most  easily  de- 
monstrated. Before  they  are  injected,  they  may  be  rendered  more  apparent,  and  even 
be  filled,  by  throwing  water  either  into  the  hepatic  arteries,  the  vena  ports,  the  hepatic 
veins,  or  the  hepatic  ducts.  In  order  to  inject  them,  it  is  sufficient  to  make  a  superfi- 
cial puncture  in  any  part  of  the  peritoneum  covering  the  liver  ;  but  it  is  most  convenient 
to  operate  upon  one  of  the  lymphatic  trunks  which  run  upon  the  surface  of  that  organ. 
It  is  of  importance  that  the  tube  should  be  introduced  between  the  peritoneal  covering 
and  the  fibrous  coat,  without  perforating  the  latter.  It  is  sufficient  to  inject  from  a  sin- 
gle vessel  in  order  to  fill  all  the  others.  The  mercury  generally  runs  as  far  as  the  near- 
est lymphatic  gland,  the  resistance  in  which  causes  the  fluid  to  flow  back  into  the  sur- 
rounding branches,  even  as  far  as  their  most  delicate  ramifications,  so  that,  in  successful 
injections,  the  whole  surface  of  the  liver  has  a  silvery  aspect ;  the  possibility  of  injecting 
the  lymphatics  of  the  liver,  from  the  trunks  towards  the  branches,  must  lead  us  to  sup- 
pose that  there  are  fewer  valves  in  them  than  in  the  lymphatics  of  other  pjirts  of  the  body. 

The  Lymphatic  Glands  of  the  Liver. 
These  are  situated  along  the  hepatic  vessels,  behind  the  pylorus,  and  are  continuous 
with  the  cceliac  lymphatic  glands.    I  have  seen  them  of  a  jet-black  colour ;  a  liquid  may 
be  expressed  from  them,  resembling  that  contained  in  the  bronchial  lymphatic  glands. 

The  Lymphatic  Vessels  of  the  Liver. 

The  lymphatics  of  the  liver  may  be  divided  into  the  superficial  and  the  deep. 

The  Superficial  Lymphatics. — These  are  subdivided  into  those  of  the  convex  and  those 
of  the  concave  surface. 

The  lymphatics  of  the  convex  surface  of  the  liver  consist  of  a  certain  number  of  trunks, 
some  of  which  belong  to  the  right  and  the  others  to  the  left  lobe.  Some  of  them  run 
from  behind  forward,  others  from  before  backward,  towards  the  posterior  border  of  the 
organ. 

The  first  set,  or  those  which  run  from  behind  forward,  reach  the  suspensory  ligament 
of  the  liver,  and  unite  into  several  trunks,  some  of  which  perforate  the  diaphragm,  enter 
the  anterior  mediastinum,  behind  the  xiphoid  cartilage,  and  tenninate  in  the  mediastinal 
lymphatic  glands  ;  while  others  are  reflected  over  the  anterior  margin  of  the  liver,  to 
gain  the  longitudinal  fissure,  along  which  they  run  as  far  as  the  gastro-hepatic  omentum, 
by  which  they  are  conducted  to  the  lymphatic  glands  placed  round  the  pylorus,  to  tbose 
around  the  cardiac  orifice  of  the  stomach,  and  to  those  which  lie  along  the  lesser  curva- 
ture of  that  organ,  and  near  the  lobulus  Spigelii. 

The  second  set  of  the  lymphatics  of  the  convex  surface  of  the  liver,  or  those  which 
run  from  before  backward,  having  reached  the  posterior  border  of  the  liver,  divide  into 
three  distinct  groups  of  vessels :  those  on  the  left  enter  the  substance  of  the  left  triangu- 
lar ligament  of  the  liver  ;  those  on  the  right  pass  into  the  right  triangular  ligament ;  while 
the  remainder,  which  occupy  the  middle,  enter  the  substance  of  the  coronary  ligament. 

Those  lymphatics  of  the  second  set  that  do  not  perforate  the  diaphragm  enter  the 
lymphatic  glands  along  the  vena  cava,  and  from  thence  reach  the  thoracic  duct.  Some 
of  them  run  along  the  lower  border  of  the  twelfth  rib,  and  open  into  the  glands  situated 
near  its  posterior  extremity,  and  into  another  gland  which  rests  upon  the  twelfth  dorsal 
vertebra. 

Those  lymphatics  of  the  second  set  which  do  perforate  the  diaphragm  pass  through 
its  crura,  and  proceed,  some  to  the  intercostal  lymphatic  glands,  or  into  those  which  lie 
along  the  vena  azygos  and  the  aorta,  and  thence  into  the  thoracic  duct ;  while  others 
enter  that  duct  directly.  I  have  seen  a  veiy  large  lymphatic  trunk  open  directly  into 
the  thoracic  duct,  opposite  the  fifth  dorsal  vertebra.  Mascagni  pointed  out  some  lym- 
phatic vessels  which,  after  having  perforated  the  fleshy  fibres  of  the  diaphragm,  ran  be- 
tween the  pleura  and  that  muscle,  re-entered  the  abdomen  through  the  aortic  opening  in 
the  diaphragm,  and  then  passed  into  the  glands  surrounding  the  aorta  and  vena  cava,  or 
entered  the  thoracic  duct  at  no  great  distance  from  the  reservoir  of  Pecquet,  without 
passing  through  any  lymphatic  glands. 

The  lymphatics  of  the  concave  surface  of  the  liver  consist  of  several  tninks,  which  are  all 
directed  from  before  backward,  and  are  divided  into  three  sets  :  those  which  are  situ- 
ated to  the  right  side  of  the  gall-bladder ;  those  which  surround  it ;  and  those  which  are 
situated  to  its  left  side. 


ANGEIOLOGY. 

Those  situated  on  the  right  of  the  gall-bladder  partly  enter  the  lumbar  glands,  and 
partly  terminate  in  the  glands  around  the  vena  cava  and  aorta. 

Those  which  surround  the  gall-bladder  lorm  a  remarkable  plexus,  vphich  accompanies 
the  hepatic  vessels,  and  terminates  in  the  lymphatic  glands  which  lie  along  those  ves- 
sels, and  in  the  glands  situated  in  the  substance  of  the  gastro-hepatic  omentum.  Among 
this  set  of  lymphatics  I  would  point  out  one  considerable  trunk,  which  runs  in  the  cellu- 
lar tissue  connecting  the  gall-bladder  to  the  liver. 

The  lymphatic  trunks  on  the  left  of  the  gall-bladder  end  in  the  oesophageal  lymphatic 
glands,  and  in  those  which  occupy  the  lesser  curvature  of  the  stomach. 

The  Deep-seated,  Lymphatics  of  the  Liver. — These  vessels  accompany  the  hepatic  ducts 
and  the  vena  portae,  and  are  contained  with  them  in  the  capsule  of  Glisson  ;  they  emerge 
from  the  transverse  fissure  of  the  liver,  penetrate  the  substance  of  the  gastro-hepatic 
omentum,  and  enter  the  lymphatic  glands  situated  along  the  lesser  curvature  of  the 
stomach  and  behind  the  pancreas. 

Those  lymphatics  of  the  liver  which  accompany  the  hepatic  artery  and  duct  and  the 
vena  ports  are  extremely  large,  and  are  often  filled  with  yellow  lymph :  they  are  some- 
times found  distended  with  gas  in  cases  of  commencing  putrefaction.  They  were  known 
long  before  the  lacteals ;  indeed,  they  were  the  first  lymphatic  vessels  that  were  dis- 
covered. 

The  Lymphatic  System  of  the  Stomach,  Spleen,  and  Pancreas. 
The  Lymphatic  Glands  of  the  Stomach,,  Spleen,,  and  Pancreas. 

Those  of  the  stomach  accompany  the  coronary  vessels  along  the  great  and  lesser  cur- 
vatures of  the  stomach  ;  some  of  them  are  situated  within  the  gastro-splenic  omentum, 
and  a  great  number  surround  the  pyloric  and  cardiac  orifices. 

The  lymphatic  glands  of  the  spleen  occupy  the  hilus  of  that  organ. 

The  pancreatic  lymphatic  glands  are  ranged  along  the  splenic  artery,  and,  consequently, 
along  the  upper  border  of  the  pancreas ;  several  of  them  are  grouped  around  the  coeliac 
axis.     They  receive  a  very  great  number  of  lymphatic  vessels. 

The  Lymphatic  Vessels  of  the  Stomach,  Spleen,  and  Pancreas. 

The  lymphatic  vessels  of  the  stomach  are  divided  into  the  superficial  and  deep. 

The  sxiperficial  lymphatics  form  a  network  beneath  the  peritoneum ;  the  deep  lyni 
phatics  arise  from  an  equally  complex  network  situated  in  the  mucous  membrane.  They 
follow  difl'erent  directions  :  a  great  number  of  them  pass  to  the  great  curvature,  and  enter 
the  glands  situated  there  ;  others  proceed  to  the  lesser  curvature,  and  pass  through  the 
glands  in  that  situation.  Several  run  towards  the  spleen,  and  enter  the  splenic  lymphat- 
ic glands  ;  and,  lastly,  others  go  to  the  lymphatic  glands  around  the  pylorus. 

It  has  been  stated  that  the  lymphatics  of  the  stomach  have  been  seen  filled  with  chyle : 
this  is  at  least  doubtful. 

The  Lymphatics  of  the  Spleen. — The  superficial  lymphatics  of  this  organ  cannot  be  seen 
unless  the  splenic  bloodvessels  have  been  previously  injected  with  size  injection :  the 
size  freed  from  the  colouring  matter  will  pass  into  them.  I  have  seen  tallow,  thrown 
into  either  the  arteries  or  veins  of  the  spleen,  pass  into  the  superficial  lymphatics.  It  is 
true  that  the  injection  was  made  forcibly,  and  kept  up  for  some  time.  The  deep  lym- 
phatics of  the  spleen  are  not  known. 

The  proper  lymphatics  of  the  pancreas  are  little  known. 

The  Lymphatic  System  of  the  Intestines. 
The  Lymphatic  Glands  of  the  Intestines. 

The  lymphatic  glands  of  the  small  intestine,  or  the  mesenteric  glands,  are  extremely  nu- 
merous. Several  anatomists,  who  have  had  the  patience  to  count  them,  have  arrived  at 
very  different  results,  partly  on  account  of  individual  varieties,  and  partly  because  sev- 
eral, having  chosen  tuberculated  subjects  for  the  purpose,  have  mistaken  the  tubercles 
for  Ijnnphatic  glands. 

The  mesenteric  glands  are  situated  between  the  folds  of  the  mesentery,  in  the  meshes  of 
the  network  formed  by  the  arteries  and  veins.  Those  which  are  nearest  to  the  intestine 
are  found  in  the  intervals  observed  between  the  vessels  of  the  mesentery  close  to  the  in- 
testine. Those  which  are  most  distant  from  the  intestine  are  situated  near  the  adherent 
border  of  the  mesentery,  along  the  trunk  of  the  superior  mesenteric  artery.  The  largest 
of  these  glands  are  found  near  the  origin  and  termination  of  that  artery.  Thus  we  find, 
below,  a  group  of  large  lymphatic  glands,  the  ileo-colic,  opposite  the  termination  of  the  il- 
eum in  the  colon.  Another  cluster,  named  the  duodenal,  is  situated  above,  in  front  of  the  du- 
odenum :  they  are  extremely  large.  We  generally  find  one  larger  than  the  rest ;  it  is  repre- 
sented in  the  oldest  works  on  anatomy,  and  has  been  sometimes  mistaken  for  the  pancreas. 

The  group  of  ileo-colic  lymphatic  glands  is  remarkable  for  frequently  becoming  inflamed 
in  follicular  enteritis. 

The  lymphatic  glands  of  the  great  intestine,  or  m^so-colic  glands,  much  less  numerous 
than  those  of  the  mesentery,  generally  lie  along  the  vascular  arches  formed  by  the  colic 
art(iries  and  veins :  several  of  them  are  situated  near  the  posterior  border  of  the  intes- 


THE   LYMPHATICS   OF   THE    INTESTINES,  ETC.  -fHI 

tine ;  and  some  are  even  found  upon  the  intestine,  accompanying  those  bloodvessels 
which  run  for  a  short  distance  beneath  the  peritoneal  coat,  and  then  penetrate  the  mus- 
cular coat.  The  meso-colic  lymphatic  glands  are  not  nearly  so  numerous  along  the 
transverse  colon  as  along  either  the  ascending  or  descending  colon.  Those  situated  in 
the  transverse  meso-colon  form  an  uninterrupted  chain  with  the  mesenteric  glands. 

The.  Lymphcaic  Vessels  of  the  Intestines. 

The  Lymphatics  of  the  Small  Intestine.— These  vessels  are  divided  into  two  sets,  the 
lymphatics,  properly  so  called,  and  the  lacteals. 

The  lymphatics,  properly  so  called,  like  those  of  the  stomach  and  great  intestine,  arise 
from  two  sets  of  networks ;  one  in  the  serous,  the  other  in  the  mucous  coats.  The  ves- 
sels which  pass  out  from  these  networks  have  a  remarkable  character,  which  was  well 
described  by  Mascagni ;  instead  of  passing  directly  into  the  mesentery,  they  first  proceed 
for  a  short  distance  along  the  intestine,  and  then  curve  and  enter  the  mesenteric  glands. 

The  lacteals,  or  lacteal  vessels  of  the  small  intestine,  can  be  easily  seen  in  an  animal  that 
has  been  killed  while  the  absorption  of  chyle  is  going  on  in  the  intestine  ;  and  they  have 
occasionally  been  observed  in  the  human  subject,  in  cases  of  accidental  death.  They 
then  appear  as  white,  nodulated,  and  slightly  flexuous  lines,  which  communicate  occa- 
sionally with  each  other,  pass  from  one  mesenteric  gland  to  another,  enter  the  lymphat- 
ic glands  situated  in  front  of  the  aorta  and  vena  cava,  and  terminate  in  the  thoracic  duct 
by  a  variable  number  of  trunks  :  the  lymphatic  plexuses  of  the  left  side  pass  behind  the 
aorta. 

The  lacteals  commence,  according  to  Lieberkuhn,  upon  the  summit  of  each  of  the  villi 
«)f  the  small  intestines,  run  down  to  its  base,  and  then  enter  at  right  angles  mto  the  sub- 
mucous lacteal  vessels,  which  invariably  perforate  the  other  coats  of  the  intestine,  on  its 
concave  border.  This  arrangement  was  very  evident  in  a  case  in  which  the  lacteals  were 
filled  with  tuberculous  matter. — {Anath.  Pathol.,  liv.  ii.,  pi.  2.)* 

The  Lymphatics  of  the  Great  Intestine. — We  may,  with  Mascagni,  divide  these  l)Tnphatics 
into  two  sets,  according  to  the  glands  in  which  they  terminate,  viz.,  those  of  the  coecum 
and  of  the  ascending  and  transverse  colon,  which  pass  through  the  meso-colic  lymphatic 
glands,  and  then  terminate  in  the  mesenteric  glands ;  and  those  of  the  descending  colon 
and  rectum,  which  enter  the  lumbar  lymphatic  glands  together  with  the  lymphatics  of 
the  genital  organs,  and  of  the  lower  extremities. 

The  Lymphatic  System  of  the  Thorax. 

The  Lymphatic  Glands  of  the  Thorax. 

The  thoracic  lymphatic  glands  are  divided  into  those  of  the  parietes  of  the  thorax, 
those  of  the  mediastinum,  and  the  bronchial  or  pulmonary  glands. 

The  lymphatic  glands  of  the  parietes  of  the  thorax  are  very  small,  and  are  thus  arranged : 
t>ie  intercostal  glands  are  situated  on  each  side  of  the  spine  near  the  costo- vertebral  ar- 
ticulations ;  some  are  placed  between  the  two  layers  of  the  intercostal  muscles  :  they 
are  very  smaU,  and  irregular  in  number.  The  sub-sternal  or  mammary  glands  are  found 
at  the  anterior  extremity  of  the  intercostal  spaces  near  the  internal  mammary  vessels, 
and  applied  along  the  borders  of  the  sternum ;  there  is  one  for  each  intercostal  space. 

The  mediastinal  lymphatic  glands  are  divided  into  those  of  the  posterior  mediastinum,  which 
are  arranged  along  the  cEsophagus  and  aorta,  and  form  a  continuation  of  the  intercostal 
glands  :  they  have  been  known  to  become  enlarged  and  press  upon  the  oesophagus,  so  as 
to  cause  dysphagia ;  and  into  those  of  the  anterior  mediastinum,  the  principal  of  which  lie 
upon  the  diaphragm  in  front  of  the  pericardium,  and  around  the  great  vessels  connected 
with  the  base  of  the  heart. 

The  bronchial  or  pulmonary  glands  were  noticed  by  the  oldest  anatomists,  and  espe- 
cially by  Vesalius,  whence  the  name  of  glandula  Vcsdiance,  by  which  they  are  still  known  : 
they  are  remarkable  for  their  situation,  number,  size,  and  colour.  They  are  situated 
along  the  bronchi  and  their  first  divisions.  The  largest  are  generally  placed  opposite 
the  bifurcation  of  the  trachea.  The  smallest  lie  within  the  substance  of  the  lungs,  around 
the  first  divisions  of  the  bronchi ;  some  of  them  are  seen  in  the  inter-lobular  fissures. 

Their  number  is  very  considerable. 

In  disease,  they  may  acquire  such  a  size  as  to  compress  and  narrow  the  bronchi,  and 
thus  prevent  the  passage  of  the  air  through  those  tubes. 

In  infancy  they  do  not  differ  in  colour  from  the  other  lymphatic  glands,  but  they  are 
black  in  the  adult,  and  especially  in  the  aged.  They  are  also  liable  to  become  the  seat 
of  depositions  of  phosphate  of  lime. 

Senac  considers  them  to  be  secreting  glands  quite  distinct  from  the  lymphatic  glands. 
Portal  divided  them  into  true  glands  and  lymphatic  glands  ;  but  no  one  has  been  able  to 
demonstrate  the  excretory  ducts,  which,  according  to  Portal,  proceed  from  the  lymphat- 
ic glands  upon  the  trachea.  The  communications  between  these  and  the  trachea,  ob- 
served in  some  cases  of  disease,  are  altogether  accidental. 

*  See  also  note,  p.  368. 

4K 


ANGEIOLOGY. 

-  The  Lymphatic  Vessels  of  the  Thorax, 

The  lymphatic  vessels  of  the  thorax  are  divided  into  those  of  the  parietes  and  those 
of  the  organs  contained  in  the  thoracic  cavity. 

The  Lymphatics  of  the  Thoracic  Parietes. — We  shall  here  merely  notice  the  deep-seat- 
ed lymphatics.  They  are  divided  into  the  intercostal,  the  sub-sternal  or  internal  mam- 
mary, and  the  diaphragmatic. 

The  intercostal  lymphatics  accompany  the  arteries  and  veins  of  that  name ;  they  re- 
ceive the  lymphatic  vessels  of  the  intercostal  muscles  and  costal  pleura,  run  along  the 
grooves  of  the  ribs,  pass  through  the  intercostal  lymphatic  glands,  reach  the  sides  of  the 
vertebrae,  unite  with  other  lymphatics  from  the  back  of  the  thorax  and  from  the  spinal 
canal,  enter  the  lymphatic  glands  on  the  sides  of  the  vertebral  column,  and  are  for  the 
most  part  directed  downward  to  terminate  in  the  thoracic  duct. 

The  sub-sternal  or  internal  mammary  lymphatics  arise  from  the  supra-umbilical  portion 
of  the  anterior  walls  of  the  abdomen  :  they  pass  into  the  thorax,  behind  the  ensiform 
cartilage,  and  form  two  bundles,  which  run  upon  the  sides  of  the  sternum,  unite  with  the 
anterior  intercostal  and  external  mammary  lymphatics,  and  enter  the  internal  mammary 
lymphatic  glands.  From  the  lowest  of  these  glands  other  lymphatics  proceed,  and  as- 
cend in  succession  from  one  gland  to  another  up  to  the  inferior  cervical  lymphatic 
glands ;  on  the  left  side  they  enter  the  thoracic  duct,  and  on  the  right,  the  great  lym- 
phatic trunk.  Sometimes,  but  rarely,  the  mjimmary  lymphatics  open  directly  into  the 
internal  jugular  and  sub-clavian  veins. 

The  lymphatics  of  the  diaphragm  for  the  most  part  unite  with  the  intercostal  and  he- 
patic lymphatics  ;  the  others  run  forward  between  the  pleura  and  the  fleshy  fibres  of  the 
diaphragm ;  some  of  them  enter  the  inferior  mediastinal  glands,  and  the  others,  the  in- 
ternal mammary  lymphatic  glands. 

The  Lymphatics  of  the  Thoracic  Viscera. — The  lymphatics  of  the  lungs  are  divided  into 
superficial  and  deep  :  the  superficial  lymphatics  may  be  injected  in  the  same  manner  as 
those  of  the  liver ;  they  form  an  extremely  close  network  beneath  the  pleura  pulmonalis, 
and  frequently  present  a  number  of,  as  it  were,  varicose  enlargements  :  these  were  no- 
ticed and  figured  by  Mascagni ;  and  the  frequency  of  their  occurrence  led  him  to  inquire 
whether  such  was  not  the  natural  structure  of  lymphatics.  Some  of  the  vessels  which 
proceed  from  this  network  run  in  the  inter-lobular  fissures,  and  enter  the  lymphatic  glands 
situated  at  the  bottom  of  these  fissures  ;  while  the  others  reach  the  internal  surface  of 
the  lung,  and  terminate  in  the  bronchial  glands. 

These  superficial  lymphatics  also  communicate  with  the  deep  lym^phatics  in  the  cel- 
lular intervals  between  the  lobules  of  the  lung. 

The  deep  lymphatics  of  the  lung  are  very  numerous  :  the  manner  in  which  they  com- 
mence in  the  lobules  is  not  well  known :  they  run  in  the  inter-lobular  cellular  tissue,  and 
all  proceed  towards  the  root  of  the  lung,  in  order  to  terminate  in  the  glands  situated 
around  the  bronchi,  and  in  several  which  lie  along  the  oesophagus.  It  is  doubtful  wheth- 
er a  single  pulmonary  lymphatic  vessel  enters  directly  into  another  lymphatic  gland 
without  first  going  through  a  bronchial  gland. 

Other  lymphatics  proceed  from  these  bronchial  glands  ;  some  of  which  pass  in  front 
of  the  trachea  to  enter  the  tracheal  lymphatic  glands,  while  the  others  proceed  to  the 
lymphatic  glands  upon  the  oesophagus.  On  the  left  side  both  sets  enter  the  thoracic 
duct,  at  a  short  distance  before  its  termination ;  these  are  more  numerous  than  those  on 
the  right  side,  which  enter  the  right  lymphatic  duct.  Some  of  them  terminate  in  the 
thoracic  duct,  before  it  emerges  from  the  thorax ;  severeil  of  these  vessels  are  sdso  seen 
to  enter  the  internal  jugular  and  sub-clavian  veins. 

I  should  observe  that,  in  consequence  of  the  above-mentioned  anatomical  fact,  the 
cervical  lymphatic  glands  sometimes  become  enlarged  in  diseases  of  the  lungs. 

The  Lymphatics  of  the  Heart,  Pericardium,  and  Thymus. — The  lymphatics  of  the  heart 
are  divided  into  superficial  and  deep ;  the  superficial  vessels  commence  by  a  sub-serous 
network,  and,  for  the  most  part,  run  along  the  right  border  of  that  organ  ;  the  deep  lym- 
phatics arise  from  the  internal  membrane  of  the  heart,  in  which  I  have  never  been  able 
to  inject  a  perfect  network  :  they  all  accompany  the  coronary  vessels,  and  all  pass  out 
of  the  pericardium ;  some  of  them  unite  with  the  lymphatics  of  the  lung ;  the  others  en- 
ter the  glands  in  front  of  the  arch  of  the  aorta  and  puhnonary  artery,  and  from  thence 
pass  to  the  thoracic  duct. 

The  lymphatics  of  the  pericardium  and  thymus  enter  the  internal  mammary,  anterior 
mediastinal,  and  bronchial  lymphatic  glands. 

The  Lymphatic  System  of  the  Head. 

The  Lymphatic  Glands  of  the  Head. 

There  are  more  lymphatic  glands  in  the  face  than  in  the  cranium. 

All  the  lymphatic  glands  of  the  cranium  are  found  upon  its  posterior  region  :  some  of 
■"them  are  situated  behind  the  ear,  along  the  attachments  of  the  occipito-frontalis  ;  several 
.are  placed  beneath  the  upper  end  of  the  sterno-mastoid  ;  they  are  very  small,  and  often 


THt;    I.YvIPHATICS    OF    THE    HEAD,    ETC.  627 

escape  notice  in  a  hasty  dissection  :  they  become  veiy  distinct  in  diseases  of  the 
scalp. 

Are  there  any  deep  lymphatics  of  the  cranium  ?  The  pituitary  body,  the  pineal  gland, 
and  the  white  bodies  known  as  the  glandulae  Pacchioni,  have  been  regarded  as  belong- 
ing to  the  lymphatic  system.  Some  authors  have  even  considered  the  tubercles,  so 
frequently  found  in  the  brains  of  infants,  and  which  are  evidently  accidental  formations, 
to  be  of  the  same  nature.  Certain  bodies  found  in  the  carotid  canal,  and  which  are 
evidently  enlargements  of  the  ganglionic  nerves,  have  also  been  described  as  lymphatic 
glands ;  but  this  opinion  is  now  completely  rejected. 

Of  the  lymphatic  glands  of  the  face,  the  largest  occupy  the  base  of  the  lower  jaw,  and 
are  called  the  sub-maxillary  l5Tnphatic  glands  :  several  of  them  are  situated  upon  the 
outer  surface  of  the  maxillary  bone,  along  the  facial  vessels,  in  front  of  the  masseter 
muscle. 

We  find,  also,  in  the  face,  the  parotid  lymphatic  glands,  some  of  which  are  superficial 
and  others  deep,  the  latter  being  situated  in  the  substance  of  the  gland :  we  find  some, 
also,  between  this  gland  and  the  masseter :  lastly,  there  are  the  zygomatic  glands,  situ- 
ated imder  the  zygoma,  and  the  buccinator  lymphatic  glands. 

TJie  Lymphatic  Vessels  of  the  Head. 

These  belong  either  to  the  cranium  or  to  the  face. 

The  Lymphatics  of  the  Cranium. — The  superficial  or  sub-cutaneous  cranial  lymphatics 
are  divided  into  two  sets :  the  temporal  lymphatics,  which  run  along  the  superficial  tem- 
poral artery,  and  pass  through  the  parotid  lymphatic  glands,  from  which  vessels  proceed 
to  the  glands  in  the  anterior  region  of  the  neck  ;  and  the  occipital  lymphatics,  which  fol- 
low the  occipital  artery,  and  terminate  in  the  mastoid  and  the  occipital  lymphatic  glands. 

The  deep  lymphatics  of  the  cranium,  the  lymphatics  of  the  dura  mater,  or  the  meningeal 
lymphatics,  accompany  the  meningeal  vessels,  escape  through  the  foramen  spinale  of  the 
sphenoid  bone,  and  enter  the  jugular  lymphatic  glands. 

Ruysch  appears  to  have  been  the  first  who  noticed  lymphatics  in  the  brain ;  he  has 
named  them  vasa  pseudo-lymphatica.  Mascagni  could  only  show  the  presence  of  the  su- 
perficial lymphatics  of  the  brain  by  injecting  coloured  size  into  the  carotid  arteries.  The 
size  freed  from  the  colouring  material  passed  into  the  lymphatics. 

The  lymphatics  of  the  brain  are  but  little  known.  M.  Fohmann  has  described  and 
figured  a  lymphatic  plexus  situated  between  the  arachnoid  and  pia  mater,  and  precisely 
resembling  those  found  in  other  parts  of  the  body.  This  network  dips  into  the  sulci, 
and  appears  to  be  continued  into  the  substance  of  the  brain,  where  it  is  no  longer  possi- 
ble to  follow  it.  From  this  network  some  small  lymphatic  trunks  proceed,  and  accom- 
pany the  arteries  and  veins  as  far  as  the  foramina,  in  the  base  of  the  cranium,  beyond 
which  M.  Fohmann  was  never  able  to  trace  them ;  so  that  he  inquires  whether  these 
vessels  do  not  form  an  exception  to  the  general  rule  from  their  want  of  connexion  with 
the  absorbent  system  generally,  and  whether  they  do  not  enter  directly  with  the  veins 
upon  which  they  are- placed.  On  the  other  hand,  Mascagni  has  figured  some  lymphatics 
around  the  internal  carotid,  within  the  carotid  canal,  and  also  around  the  vertebral  ar- 
teries and  internal  jugular  vein.  The  existence  of  these  trunks  leads  us  to  suppose 
that  there  must  be  cerebral  lymphatics. 

M.  Fohmann  has  also  found  lymphatics  in  the  choroid  plexuses  of  the  lateral  ventri- 
cles of  the  brain :  these  vessels  were  remarkably  dilated,  so  as  to  present  ampullae. 

The  Lymphatic  Vessels  of  the  Face. — These  are  divided  into  the  superficial  and  deep. 

The  superficial  lymphatics  are  much  more  numerous  than  those  of  the  cranium.  They 
commence  upon  all  parts  of  the  face ;  those  from  the  frontal  region  accompany  the 
frontal  vessels  :  the  others  accompany  the  adjacent  bloodvessels ;  several  of  them  pass 
through  the  buccinator  glands,  and  they  all  finally  enter  the  sub-maxillary  lymphatic 
glands.  The  lymphatics  of  the  face  are  to  be  injected  by  introducing  the  pipe  into  the 
plexus  contained  in  the  skin. 

The  deep  lymphatics  of  the  face  accompany  the  bloodvessels.  They  are  divided  into 
those  of  the  temporal  fossae,  those  of  the  zygomatic  and  pterygo-maxillary  fossae,  and 
those  of  the  nasal  fossae.  The  lymphatics  of  the  pharynx,  velum  palati,  mouth,  tongue, 
and  larynx,  enter  the  deep  parotid  and  the  cervical  lymphatic  glands.  The  lymphatic 
plexuses  of  the  pituitary  membrane,  and  of  the  lingual,  buccal,  and  pharyngeal  mucous 
membranes,  may  be  perfectly  injected.  Indeed,  it  is  only  in  that  way  that  we  can 
demonstrate  the  lymphatic  vessels  which  emerge  from  these  diflTerent  parts 

The  Lymphatic  System  of  the  Cervical  Regions. 
The  Cervical  Lymphatic  Glands. 
The  lymphatic  glands  of  the  neck  are  concentrated  in  the  anterior  region  of  the  neck. 
They  are  divided  into  the  superficial  and  deep. 

The  superficial  lymphatic  glands  of  the  neck  are  found  principally  along  the  external 
jugular  vein  ;  they  are  therefore  situated  between  the  platysma  and  the  stemo-mastoid  ; 
and  in  the  supra-clavicular  triangle,  that  is  to  say,  in  the  triangulfr  interval  between  the 


6!^  ANGEIOLOGY. 

«>- 
clavicle,  the  sterno-mastoid,  and  the  trapezius.    We  also  find  several  very  small  supei- 
ficial  glands  between  the  os  hyoides  and  the  thyroid  cartilage,  and  upon  the  sides  of  the 
larynx. 

The  deep  lymphatic  glands  of  the  neck  are  very  numerous,  and  form  an  uninterrupted 
chain  around  the  internal  jugular  vein  and  the  carotid  artery,  from  the  mastoid  process 
to  the  superior  opening  of  the  thorax,  in  front  of  the  vertebral  column,  and  upon  the 
sides  of  the  pharynx  and  oesophagus. 

The  tracheal  lymphatic  glands  are  also  continuous  with  the  deep  cervical  glands. 

The  cervical  glands  form  a  continued  series  with  the  facial  and  sub-maxillary  lym- 
phatic glands  on  the  one  hand,  and  with  the  lymphatic  glands  of  the  thorax  and  axilla 
on  the  other. 

The  Cervical  Lymphatic  Vessels. 

The  cervical  lymphatics  consist  of  those  which  have  passed  through  the  sub-maxillary 
and  facial  lymphatic  glands,  and  which  afterward  traverse  the  chain  of  glands  along  the 
jugular  veins.  They  are  joined  by  those  of  the  pharynx,  oesophagus,  larynx,  trachea, 
and  thyroid  gland.  They  then  proceed  from  one  lymphatic  gland  to  another,  and  from 
one  plexus  to  another,  down  to  the  lower  part  of  the  neck,  where  they  are  joined  by 
some  lymphatics  from  the  lung,  which  also  pass  through  some  of  the  cervical  glands  : 
they  terminate  on  the  left  side  in  the  thoracic  duct,  and  on  the  right  side  in  the  right 
lymphatic  duct. 

The  Lymphatic  System  of  the  Upper  Extremity. 

The  Lymphatic  Glands  of  the  Upper  Extremity  and  of  the  Upper  Part  of  the 

Trunk. 

There  are  generally  no  lymphatic  glands  in  the  hand  or  forearm,  but  Meckel  found 
several  very  small  ones  along  the  ulnar  and  radial  bloodvessels.  There  are  two  or  three 
which  are  sub-cutaneous  in  the  front  of  the  bend  of  the  elbow,  and  one  or  two  above  the 
internal  condyle  of  the  humerus,  behind  the  basilic  vein ;  in  the  arm  we  also  find  a  se 
ries  of  small  lymphatic  glands,  which  are  never  numerous,  along  the  inner  side  of  the 
humeral  artery. 

The  axillary  lymphatic  glands  are  situated  deeply  in  the  axilla,  and  are  very  numerous , 
some  lie  along  the  great  vessels,  others  are  scattered  through  the  axilla :  they  are  often 
of  a  very  large  size. 

The  following  may  be  regarded  as  appendages  of  the  axillary  glands :  a  small  sub-cla- 
vicular gland,  situated  deeply  beneath  the  costo-coracoid  membrane,  opposite  the  trian- 
gular interval  between  the  pectoralis  major  and  the  deltoid,  and  two  or  three  small  glands 
situated  along  the  attachments  of  the  pectoralis  major,  as  far  as  the  mammary  gland. 

Mascagni  has  figured  a  small  lymphatic  gland  near  the  umbilicus. 

The  Lymphatic  Vessels  of  the  Upper  Extremity  and  of  the  Upper  Half  of  the 

Trunk. 

The  Lymphatics  of  the  Upper  Extremity. — The  superficial  set  of  these  vessels  arise 
from  the  skin  of  the  hand,  and  run  parallel  to  the  fingers  :  they  are,  for  the  most  part,  sit- 
uated upon  the  back  of  the  hand ;  they  cross  obliquely  over  the  metacarpal  bones,  pass 
over  the  carpus,  and  thus  reach  the  forearm. 

In  the /orcarm  they  are  distributed  almost  equally  upon  its  anterior  and  posterior  aspects. 

The  anterior  lymphatics  are  collected  upon  the  inner  and  outer  sides  of  the  forearm  ; 
having  reached  the  elbow,  some  pass  in  front  of  the  epitrochlea  and  its  muscles  ;  others 
in  front  of  the  epicondyle.  In  this  place  they  are  re-enforced  by  the  lymphatics  from 
the  posterior  aspect  of  the  forearm,  which  are  also  collected  into  an  outer  and  innei' 
group.  Not  unfrequently  a  certain  number  of  the  posterior  lymphatics,  which  arise  from 
the  outer  side  of  the  hand  and  forearm,  after  ascending  almost  vertically  for  some  dis- 
tance, pass  obliquely,  or  cross  transversely  inward,  above  and  below  the  olecranon,  and 
unite  with  the  inner  group. 

In  the  arm  some  of  the  inner  group  of  lymphatics  pass  to  the  lymphatic  glands  above 
the  epitrochlea  ;  the  others  run  along  the  inner  border  of  the  biceps  muscle  and  basilic 
vein,  and  then  pass  backward  and  upward  to  reach  the  axillary  glands. 

The  external  lymphatics  cross  very  obliquely  over  the  anterior  aspect  of  the  arm,  to 
terminate,  like  the  preceding,  in  the  axillary  glands.  One  of  them  has  a  remarkable 
course  ;  it  runs  along  the  cephalic  vein,  gains  the  cellular  interval  between  the  pectoral- 
is major  and  the  deltoid,  dips  down  over  the  upper  edge  of  the  pectorahs  minor  and  be- 
low the  costo-coracoid  membrane,  and  describes  a  curve  so  as  to  enter  the  sub-clavicu- 
lar lymphatic  ganglion. 

The  deep  lymphatics  of  the  upper  extremity  exactly  follow  the  course  of  the  bloodves- 
sels ;  they  often  communicate  with  the  superficial  lymphatics,  and  terminate  in  the  ax- 
illary glands.  I  have  seen  some  of  the  deep  lymphatics  of  the  forearm  communicate  at 
the  bend  of  the  elbow  with  the  superficial  lymphatics  on  the  outer  part  of  the  back  of  the 
arm,  and  enter  the  glands  above  the  epitrochlea. 


THE  SKIN.  010111^ 

The  Lymphatic  Vessels  of  the  Upper  Half  of  the  Trunk. — We  have  seen  that  all  the  lym- 
phatics of  the  sub-umbilical  portion  of  the  trunk  enter  the  inguinal  glands  ;  and  so  all  the 
lymphatic  vessels  of  the  supra-umbilical  portion  terminate  in  the  axilla. 

The  anterior  and  lateral  lymphatics  pass  upward  upon  the  pectoralis  major  and  the  ser- 
ratus  magnus,  to  gain  the  axilla. 

The  posterior  lymphatics  are  divided  into  those  of  the  neck  and  those  of  the  back ;  the 
posterior  cervical  lymphatics  descend  upon  the  trapezius  and  the  deltoid,  and  are  reflected 
over  the  posterior  border  of  the  leist-named  muscle,  in  order  to  reach  the  cavity  of  the 
axilla ;  the  posterior  dorsal  lymphatics  run  in  different  directions  ;  some  horizontally,  the 
others  from  below  upward,  to  be  reflected  into  the  axilla  below  the  tendons  of  the  la- 
tissimus  dorsi  and  teres  major. 


NEUROLOGY. 

Neuroloot  is  that  part  of  anatomy  which  treats  of  the  apparatus  of  sensation  and  in- 
nervation :  this  apparatus  consists  of  the  organs  of  the  senses,  of  the  cerebrospinal  axis, 
or  central  portion  of  the  nervous  system,  and  of  the  nerves,  or  peripheral  portion  of  that 
system. 

THE  ORGANS  OF  THE  SENSES. 
The  Skin — its  External  Characters,  Structure,  and  Appendages. — The  Tongue  considered  as 
the  Organ  of  Taste. — The  Organ  of  Smell — the  Nose — the  Pituitary  Membrane. — The  Or- 
gan of  Sight — the  Eyebrows — the  Eyelids — the  Muscles  of  the  Orbit — the  Lachrymal  Ap- 
paratus— the  Globe  of  the  Eye,  its  Membranes  and  Humours — the  Vessels  and  Nerves  of  the 
Eye. — The  Organ  of  Hearing — the  External  Ear — the  Middle  Ear  or  Tympanum — the 
Internal  Ear  or  Labyrinth — the  Nerves  and  Vessels  of  the  Ear. 

The  organs  of  the  senses  are  certain  parts  of  our  bodies  which  are  intended,  by  means 
<n  the  sensibility  they  possess,  to  establish  relations  between  us  and  external  objects. 
The  organs  of  the  senses,  to  use  a  strong  figurative  expression,  are,  as  i«  were,  the 
bridges  which  connect  the  individual  with  the  world  around  him. — (^Meckel's  Anatomy,  by 
Jourdan,  p.  471.) 

The  organs  of  the  senses,  being  placed  between  the  brain  and  surrounding  objects, 
have  the  following  characters  in  common :  they  occupy  the  surface  of  the  body ;  they 
communicate  with  the  brain  by  means  of  nerves  of  greater  or  less  size ;  and,  lastly,  each 
of  them  has  a  peculiar  structure  in  harmony  with  that  particular  quality  of  matter,  the 
perception  of  which  it  is  intended  to  convey  to  us. 

Anatomists  generally  admit  five  organs  of  sense,  which  we  shall  name,  and  then  de- 
scribe in  the  following  order :  the  skin,  or  the  organ  of  tact  and  touch,  the  organ  of  taste 
the  organ  of  smell,  the  organ  of  sight,  and  the  organ  of  hearing. 

The  Skin. 
General  Remarks  on  the  Skin. 
The  skin,  the  proper  organ  of  tact  and  of  touch,  is  a  membrane  which  serves  as  a  cov- 
ering or  integument  to  the  body,  and  is  so  accurately  moulded  upon  it  as  to  preserve  the 
form,  and  yet  conceal  the  inequalities,  of  its  entire  surface.  It  may  be  regarded  as  form- 
ing an  external  surface  or  limit,  endowed  at  the  same  time  with  sensibility  and  a  poicer 
of  resistance ;  enabling  us  by  the  one  to  perceive  such  qualities  of  bodies  as  are  distin- 
guishable by  the  touch,  and  by  the  other  preserving  us,  to  a  certain  extent  from  their  ac- 
tion. It  forms,  moreover,  an  exhalant  surface,  or  sudorific  organ,  by  which  the  system 
is  freed  from  noxious  substances,  and  also  an  inhalant  surface,  by  which  fluids  may  be 
absorbed.* 

External  Characters. 

Examined  in  reference  to  its  external  characters,  the  skin  presents  an  external  or  free 
surface,  and  an  internal  or  adherent  surface. 

The  Free  Surface. — Upon  the/r«e  surface  of  the  skin  the  following  objects  require  at- 
tention :  its  folds,  or  wrinkles,  and  its  furrows  ;  a  peculiar  colour,  which  is  subject  to 

*  Some  ancient  authors,  Marcus  Aurelius  Severinus  among  others,  adhering  closely  to  the  order  of  super- 
imposition,  which  is  sometimes  called  the  anatomical  order,  commenced  the  description  of  the  human  body 
with  the  skin ;  and  the  same  part,  though  for  a  very  different  reason,  is  described  first  by  M.  de  Blainville,  in 
his  Anatomic  Comparie :  that  celebrated  naturalist,  carrying  out  analogical  induction  to  its  utmost  limit», 
makes  the  skin  the  fundamental  organ  of  the  body,  connecting  with  it  all  the  organs  of  the  senses,  which  he 
regards  as  analogous  to  hairs,  and  names  phanerac  (a  word  constructed  by  M.  Blainville  in  opposition  to  the 
term  crypto:,  hidden,  and  derived  from  ipapcfiog,  evident,  manifest,  apparent).  He  considers  that  the  appa- 
ratus of  locomotion  is  a  development  of  the  elastic  element  of  the  skin,  which  becomes  endowed  with  contractili- 
ty ;  the  digestive  and  respiratory  organs  he  regards  as  modifications  of  the  absorbent  apparatus  of  tlie  skin  ; 
and  the  organs  of  secretion  and  generation  as  developments  of  its  e.xhalant  structure.  The  circulatory  appa- 
ratus alone  is  not  derived  by  him  immediately  from  the  external  integuments  ;  yet  he  almost  believes  that  it 
is  an  extension  or  prolongation  of  the  meshes  of  the  cutaneous  cellular  tissue 


'6S0  NEUROLOGY. 

variety  in  different  races  of  men,  and  in  different  individuals  ;  certain  horny  growths,  as 
the  nails  and  hairs,  which  are  appendages  of  the  skin  ;  and,  lastly,  numerous  orifices  for 
the  escape  of  the  cutaneous  secretions,  some  of  them  being  the  orifices  of  the  sebaceous 
foUicles,  others  of  the  sudorific  glands,  while  others,  again,  are  the  foramina,  or  depres- 
sions through  which  the  hairs  protrude.  The  horny  growths  of  the  skin  will  be  noticed 
presently  ;  and  its  colour  and  orifices,  or  pores,  will  be  examined  under  the  head  of  its 
structure. 

We  shall  here  make  a  few  remarks  upon  the  different  folds  or  wrinkles  found  in  the 
surface  of  the  skin  :  they  are  of  several  kinds. 

Some  of  them  may  be  termed  folds  of  locomotion ;  they  are  permanent,  and  are  inhe- 
rent, as  it  were,  in  the  skin  itself,  and  have  distinct  relations  to  the  various  movements 
of  the  body.  They  are  of  two  kinds  :  the  larger  folds  are  observed  around  the  joints,  both 
on  the  aspect  of  flexion,  and  that  of  extension ;  for  example,  over  the  knuckles  and  in 
the  palms  of  the  hands  ;  the  small  folds  are  found  over  the  whole  surface  of  the  skin, 
which  is  divided  by  them  into  irregular  lozenge-shaped  intervals  ;  it  is  to  these  folds  that 
the  skin  owes  its  extensibility. 

Other  folds,  called  wrinkles,  are  produced  by  the  contraction  of  sub-cutaneous  muscles ; 
such  as  the  transverse  wrinkles  produced  by  the  action  of  the  occipito-frontalis,  the  ver- 
tical wrinkles  by  that  of  the  corrugatores  supercilii,  and  the  radiated  folds  caused  by  the 
contractions  of  the  orbicularis  palpebrarum,  the  orbicularis  oris,  and  the  sphincter  ani. 
These  wrinkles,  like  the  contraction  of  the  muscles  by  which  they  are  produced,  are  only 
transitory  ;  but  they  become  permanent  when  their  causes  are  frequently  repeated.  In 
the  same  class  as  these  we  must  include  the  corrugations  of  the  skin  of  the  scrotum, 
from  contraction  of  the  dartos. 

The  folds  or  wrinkles  resulting  from  age  and  from  emaciation  depend  upon  the  skin  be 
coming,  after  more  or  less  distension,  too  much  stretched,  and,  therefore,  too  loose  to  fit 
closely  to  the  parts  beneath.  Hence,  emaciation  in  young  subjects  does  not  produce  the 
same  effects  as  in  the  aged  ;  for  in  the  latter,  the  wrinkles  are  caused  by  the  want  of 
elasticity  in  the  skin,  and  they  are  more  distinct  in  proportion  as  that  property  is  lost. 
In  cases  of  extreme  distension,  when  the  skin  has  been  altered  in  its  texture,  the  wrinkles 
are  more  marked,  and  are  permanent ;  as,  for  example,  those  observed  on  the  abdomen 
of  females  after  pregnancy,  and  of  either  sex  after  dropsy. 

Furrows  between  the  Papilla. — It  is  necessary  carefully  to  distinguish  from  the  folds  or 
wrinkles  of  the  skin  those  more  or  less  regular  but  slight  furrows  which  exist  between 
the  linear  ridges  or  eminences  formed  by  the  cutaneous  papillae  in  the  palm  of  the  hand 
and  the  sole  of  the  foot,  and  which  are  also  found,  though  in  a  less  marked  degree,  in  all 
other  parts  of  the  body. 

Adherent  Surface  of  the  Skin. — In  mammiferous  animals  the  skin  is  lined  throughout 
the  greater  part  of  its  extent  by  a  layer  of  muscular  fibres,  which  are  intended  to  act 
upon  it,  and  constitute  the  cutaneous  muscle  or  panniculus  carnosus ;  but  in  man  the  only 
traces  of  this  structure  are  the  platysma  myoides  and  the  palmaris  brevis. 

The  sub-cutaneous  muscles  of  the  human  subject  are  concentrated  in  the  face.  It 
follows,  therefore,  that,  although  in  animals  the  passions  can  be  expressed  by  move- 
ments of  the  entire  surface  of  the  body,  in  man  their  expression  is  limited  to  the  face. 
It  has  been  erroneously  supposed  that  the  phenomenon  termed  cutis  anserina,  or  goose- 
skin,  a  corrugated  condition  of  the  skin,  in  which  the  bulbs  of  the  hairs  are  rendered 
prominent  by  being  forced  outward,  depends  upon  the  contraction  of  a  layer  of  muscular 
fibres  situated  beneath  the  integument.  But  the  most  careful  examination  has  demon- 
strated no  muscular  fibres  there ;  we  do  not  even  find  a  dartoid  tissue,  such  as  is  ob- 
served wherever  there  exists  a  certain  kind  of  active  contractility  independent  of  the  will. 

Beneath  the  skin  of  the  human  subject  we  find  a  layer  of  adipose  tissue,  panniculus 
adiposus ;  it  varies  in  thickness,  and  is  contained  in  the  meshes  formed  by  the  fibrous 
lamellae,  which  extend  from  the  internal  surface  of  the  skin,  and  are  then  either  attached 
to  the  investing  aponeuroses  where  the  skin  is  said  to  be  adherent,  or  become  expanded 
into  a  very  thin  aponeurotic  membrane,  called  the  fascia  superficialis,  in  which  case  the 
skin  is  movable.  The  quantity  of  sub-cutaneous  adipose  tissue,  and  the  fixed  or  mo- 
vable condition  of  the  skin,  have  a  constant  and  necessary  relation  with  the  functions  of 
each  particular  region.  Thus,  while  adipose  tissue  is  very  abundant  in  the  palm  of  the 
hand  and  sole  of  the  foot,  where  we  always  find  a  cushion  of  fat,  it  is  never  present  in 
the  skin  of  the  eyelids  and  penis. 

When  the  skin  over  any  bony  eminence  is  required  to  be  very  movable,  and  at  the 
same  time  is  exposed  to  continual  friction,  we  find  beneath  it  a  sort  of  synovial  capsule, 
or  bursa,  as  it  is  called ;  some  of  these  bursse  exist  at  birth,  and  belong  to  the  original 
organization  ;  while  others  are  accidental,  and  result  from  friction. 

We  must  regard  the  sub-cutaneous  adipose  tissue  as  a  dependance,  or  even  as  a  con- 
stituent part,  of  the  integument,  for  it  is  impossible  to  separate  one  completely  from  the 
other.  The  adipose  tissue,  in  fact,  penetrates  into,  and  entirely  fills  the  areolar  spaces 
in  the  skin. 

The  cutaneous  vessels  enter  or  pass  out,  and  the  cutaneous  nerves  penetrate  at  the 


STRUCTURE  OP  THE    SKIN.  631 

adherent  surface  of  the  skin,  and  more  particularly  opposite  the  areolas  observed  on  that 
surface  ;  so  that  whenever  the  skin  is  stripped  off  for  a  certain  extent,  it  either  sloughs 
off,  or  its  vitality  is  so  greatly  impaired  as  to  be  incapable  of  completing  the  process  of 
cicatrization.  An  accurate  idea  is,  perhaps,  not  generally  entertained  of  the  enormous 
quantity  of  nervous  filaments  and  of  the  immense  number  of  arteries  which  enter  the 
skin,  or  of  the  number  of  veins  which  issue  from  it.  Its  importance,  both  in  a  healthy  and 
in  a  diseased  condition,  is  sufficiently  explained  by  these  anatomical  facts  regarding  it. 

Structure  of  the  Skin. 

The  skin  consists  essentially  of  the  cutis,  dermis,  or  true  skin  (a,  fig.  226) ;  of  the  pa- 
pillcR,  which  project  upon  its  external  surface  ;  of  the  pigmentum,  or  colouring  matter  (i') ; 
of  the  lymphatic  network ;  and  of  the  epidermis,  or  cuticle  (b) ;  as  accessory  parts,  it  edso 
contains  the  sebaceous  follicles,  as  well  as  arteries,  veins,  lymphatics,  and  nerves ;  and  has 
connected  to  it  the  hairs  and  the  nails. 

The  Cutis  or  Chorion. — The  dermis,  chorion,  or  cutis  vera  (a,  fig.  226  ;  e,  fig.  227),  is  the 
fundamental  part  or  the  basis  of  the  skin ;  and  to  it  the  skin  owes  ^    226 

its  strength,  extensibility,  and  elasticity.  If  the  skin  be  regarded 
as  formed  of  several  distinct  layers,  the  dermis  constitutes  the 
deepest  of these. 

The  thickness  of  the  dermis  varies  in  different  parts,  but  is  always 
in  proportion  to  the  amount  of  resistance  which  it  is  required  to 
offer.  Thus,  in  the  cranium,  it  is  very  thick  and  dense  ;  on  the  face, 
generally,  it  is  thinner  than  on  the  cranium,  but  not  in  every  part 
of  the  face.  Compare,  for  example,  its  density  and  thickness  in 
the  skin  upon  the  lips  with  its  tenuity  and  delicacy  in  that  of  the 
eyelids.  On  the  trunk  it  is  almost  twice  as  thick  behind  as  in  front ; 
and  upon  the  penis,  scrotum,  and  mamma  it  is  much  thinner  and 
finer  than  upon  any  other  part  of  the  anterior  aspect  of  the  body.  skJnofNesro. 

In  the  limbs  the  dermis  is  much  thinner  on  the  surfaces  which  are  turned  towards  the 
median  line  and  on  the  aspect  of  flexion,  than  it  is  on  the  outer  side  of  the  limbs  and  on 
the  aspect  of  extension,  which  are  more  exposed  to  the  action  of  external  objects.  On 
the  palms  of  the  hands  and  soles  of  the  feet,  which  are  almost  incessantly  in  contact 
with  external  objects,  the  dermis  is  very  thick. 

The  thickness  of  the  dermis  varies  in  different  individuals,  and  also  according  to  sex 
and  age.  In  old  persons  it  participates  in  the  general  atrophy  of  the  tissues,  and  be- 
comes so  thin  as  to  be  somewhat  translucent,  and  enables  us  in  certain  regions  to  dis- 
tinguish beneath  it  the  pearly  aspect  of  the  tendons,  and  the  reddish  colour  of  the  muscles. 

The  dermis  has  a  deep  surface,  and  an  epidermic  or  papillary  surface. 

The  deep  surface  presents  a  number  of  conical  depressions,  the  base  of  each  of  which 
corresponds  to  the  sub-cutaneous  layer  of  adipose  tissue,  while  its  summit  is  directed 
towards  the  outer  surface  of  the  skin,  and  is  pierced  with  very  fine  openings.  These 
depressions  or  alveoli,  which  are  most  strongly  developed  in  the  soles  of  the  feet  and 
palms  of  the  hands,  are  filled  with  conical  prolongations  or  masses  of  fat,  which,  when 
inflamed,  give  rise  to  boils,  and  in  a  state  of  gangrene,  constitute  the  slough  from  such 
sores. 

When  examined  in  reference  to  its  structure,  the  dermis  is  found  to  be  composed  of 
bundles  of  ceUulo-fibrous  tissue,  interlaced  with  each  other,  and  becoming  closer  and 
closer  towards  its  external  surface  :  this  fibrous  tissue  is  scarcely  extensible  or  eleistic, 
so  that  the  extensibility  and  elasticity  of  the  skin  are  due,  not  to  the  nature  of  the  der- 
moid tissue,  but  to  the  arrangement  of  its  component  bundles.*  The  elasticity  of  a  tis- 
sue may  depend,  like  that  of  caoutchouc,  upon  the  nature  of  its  material,  or,  like  that  of 
a  spiral  piece  of  brass  wire,  may  result  from  the  arrangement  of  that  material.  The  elas- 
ticity of  the  skin  appears  to  be  of  the  latter  kind. 

The  PapUlm. — Upon  the  external  or  epidermic  surface  of  the  cutis  are  found  a  multi- 
tude of  small  eminences,  which  are  either  arranged  side  by  side,  in  rows  or  ridges  {d, 
fig.  227),  as  in  the  palms  of  the  hands  and  soles  of  the  feet,  or  are  irregularly  scattered 
over  the  surface.  These  eminences  are  called  the  cutaneous  papilla  ;  together,  they  con- 
stitute the  papillary  body  {corpus  papillare).  To  understand  them  properly,  we  must  ex- 
ami  le  a  section  of  a  portion  of  skin  from  the  palm  of  the  hand  or  the  sole  of  the  foot, 
which  section  should  be  made  transversely  to  the  direction  of  the  papillary  ridges  (see 
fig.  227) :  nimierous  small  eminences  are  then  seen  projecting  from  the  dermis  into  the 
substance  of  the  epidermis,  which  may  be  distinguished  from  these  projections  by  its 
transparency  and  its  horny  appearance.  The  papillae  are  still  more  distinctly  seen  by  re- 
moving the  epidermis  from  a  piece  of  skin,  and  then  examining  the  latter  under  a  thin 
layer  of  fluid. 

The  papillae  consist  of  a  spongy  erectile  tissue,i-  containing  nervous  filaments,  arter- 
ies, and  veins. 

*  The  dermoid,  like  other  cellular  and  fibrous  tissues,  is  resolved  into  gelatine  by  boiling.  It  acquires  great 
density  and  strength  in  the  process  of  tanning,  by  which  it  is  converted  into  leather. 

t  It  is  impossible  to  doubt  the  analosv  of  the  papilla;  of  the  skin  to  those  of  the  tongue,  and  even  to  the  in- 


632  NEUROLOGY. 

Tl:e  nerves  of  the  papillae  are  very  numerous.  In  reference  to  this  point,  it  is  observed 
that  the  number  of  nervous  filaments  distributed  to  the  skin  is  always  in  a  direct  ratio 
with  the  number  and  size  of  the  cutaneous  papiUae  ;  and  hence  the  nerves  of  the  skin 
covering  the  palm  of  the  hand  are  exceedingly  numerous. 

Several  anatomists  state  that  they  have  seen  the  nerves  spreading  out  like  pencils  in 
the  papillae  themselves.* 

The  papillae  receive  both  arteries  and  veins  ;  in  successful  injections  with  mercury, 
or  with  glue-size,  spirit-varnish,  or  turpentine,  coloured  with  vermilion,  all  the  papillae 
are  penetrated  by  the  injection,  and  exhibit,  both  in  their  interior  and  on  their  surface,  a 
vascular  network,  which  might  be  called  an  erectile  tissue.  + 

Lymphatics  of  the  Skin. — If  we  introduce  the  pipe  of  the  mercurial  injecting  apparatus 
very  obliquely  beneath  the  epidermis,  the  mercury,  if  the  process  is  successful,  will  run 
into  a  sub-epidermic  network  of  vessels,  and  will  soon  cover  the  skin  with  a  metallic  lay- 
er. These  vessels  are  most  evidently  lymphatics,  for  the  mercury  soon  passes  from 
them  into  the  sub-cutaneous  lymphatic  vessels,  and  from  them  into  the  adjacent  lym- 
phatic glands  :  in  no  case  does  it  enter  the  bloodvegsels. 

Mascagni,  who  has  given  so  many  representations  of  the  vessels  of  the  skin  in  his 
beautiful  plates,  has  delineated  in  several  of  them  this  lymphatic  network,  lying  super- 
ficially to  the  layer  of  bloodvessels. 

The  universal  prejudice  against  microscopical  observations  had  very  improperly 
thrown  some  discredit  upon  the  positive  results  obtained  by  this  great  anatomist,  when 
an  accidentally  successful  injection  enabled  Haase  to  trace  and  delineate  the  cutaneous 
lymphatics  of  the  groin  from  the  skin  to  the  inguinal  glands. t  M.  Lauth,  also,  by  acci- 
dent, injected  the  lymphatic  network  of  the  same  region.  Panizza,  in  1830,  clearly  de- 
monstrated the  arrangement  of  the  superficial  lymphatic  network  upon  the  glans  penis 
and  the  prepuce,  in  his  beautiful  injections  of  that  organ  in  the  human  subject  and  in  an- 
imals. Lastly,  M.  Fohmann  {Essai  sur  les  Vaisseaux  Lymphatiques  do  divers  Ordrcs,  1833) 
has  made  some  special  researches  upon  this  subject,  viz.,  upon  the  lymphatic  network 
in  the  skin  and  in  other  parts.  Two  beautiful  plates,  one  representing  the  skin  of  the 
mamma,  and  the  other  that  of  the  scrotum,  glans  penis,  and  prepuce,  give  a  perfect  idea 
of  the  arrangement  of  this  network,  which,  when  filled  with  mercury,  forms  a  silvery 
layer  beneath  the  epidermis.  From  this  network  branches  are  given  off  which  perforate 
the  dermis  in  all  directions,  and  enter  the  sub-cutaneous  lymphatic  vessels  proceeding 
from  its  internal  surface.  We  have  succeeded  perfectly  in  injecting  the  sub-cutaneous 
lymphatic  vessels  in  the  entire  lower  extremity  of  a  new-born  infant,  merely  by  introdu- 
cing the  pipe  into  the  sole  of  the  foot. 

This  lymphatic  network  is  remarkable  for  being  situated  superficially  to  the  bloodves- 
sels, as  Mascagni  had  correctly  observed,  and  for  being  completely  independent  of  any 
other  system  of  vessels ;  also,  for  its  vessels  being  dilated  into  ampullae  at  various  pla- 
ces, for  being  destitute  of  valves,  and  for  not  opening  anywhere  upon  the  surface  of  the 
skin  ;  so  that,  excepting  from  laceration,  the  mercury  does  not  escape  through  the  pores 
of  the  epidermis.  Lastly,  the  network  generally  consists  of  two  very  distinct  layers,  sit- 
uated between  the  epidermis  and  the  dermis  ;  one  extremely  delicate  and  superficial, 
the  other  lying  immediately  upon  the  dermis,  and  belonging  to  deeper  vessels.^ 

The  Pigmentum. — All  the  different  shades  of  colour  observed  in  the  skin  of  the  sev- 
eral races  of  mankind  belong  to  either  the  white,  the  black,  or  the  copper-coloured  va- 
riety :  they  depend  upon  the  presence  of  a  colouring  matter  called  the  pigmentum,  which 
exists  in  the  European  as  well  as  in  the  negro,  though  in  a  less  marked  degree,  and 
which  is  deposited  beneath  the  epidermis. 

This  colouring  matter,  or  pigmentum  (b',  fig.  226  ;  c,  fi^.  227),  may  be  demonstrated  in 
the  skin  of  the  negro  (represented  in  fig.  226)  with  the  greatest  facility  by  means  of 
maceration.  It  is  tlien  found  not  to  be  contained  in  special  vessels,  as  Bichat  supposed, 
but  to  be  deposited  beneath  the  epidermis,  where  it  constitutes  a  uniform  layer,  that 
either  comes  off  with  the  epidermis  or  remains  attached  to  the  dermis,  but  is  independ- 
ent of  either. II  The  epidermis,  the  papillae,  and  the  chorion  are  of  precisely  the  same 
colour  in  the  negro  as  in  the  white  races.     The  pigmentum  of  the  skin  is  identical  in 

testinal  villi.  Although  we  are  unacquainted  with  their  precise  structure,  it  is  enough  to  know  that  they  are 
composed  of  an  erectile  spong-y  tissue,  in  which  both  nerves  and  vessels  terminate.  The  nervous  lilaraentscan 
be  traced  by  dissection  as  far  as  the  bottom  of  the  alveolar  depressions  in  the  dermis. 

*  Analysis  of  a  former  Memoir  upon  the  Structure  and  Functions  of  the  Skin,  by  MM.  Breschet  and  Rous- 
sel  de  Vauzfime.  These  authors  state  that  they  have  ascertained  that  the  nerves  of  the  skin  terminate  in  loops 
or  arches,  as  had  been  pointed  out  by  MM.  Prevost  and  Dumas,  in  regard  to  the  nerves  of  the  muscles.  We 
shall  elsewhere  see  what  is  to  be  thought  concerning  the  existence  of  thesu  terminal  loops  of  the  nerves  in 
muscles,  and  the  theory  of  muscular  contraction  founded  upon  it. 

t  [The  papillae  are  prolongations  of  the  vascular  and  nervous  chorion.] 

X  De  Vasis  Cutis  et  Intestinorum  Absorbentibus,  LipsiiK,  1789.  In  the  plate  given  iu  this  work,  the  lym- 
phatic plexus  is  very  badly  represented. 

^  According  to  M.  Fohmann,  the  skin  is  composed  of  the  following  parts  proceeding  from  within  outward  : 
1.  The  panniculus  adiposus.  2.  The  internal  layer  of  the  dermis,  characterized  by  its  fibrous  moshes.  3.  A 
vascular  layer  composed  of  lymphatics,  and  the  terminations  of  the  bloodvessels  and  veins,  united  by  a  small 
quantity  of  animal  matter.  4.  A  vascular  network,  formed  exclusively  by  the  ultimate  rami ficatious  of  '  le  lym- 
phatics,    5.  The  rete  mucosum  of  Malpighi.     0.  The  epidermis.  !i  See  not«    .    635. 


THE    PIGMENTUM.  63S 

every  respect  with  the  choroid  pigment  in  the  eye,  and  is  formed  of  black  molecules  in- 
soluble in  water.  Blumenbach  conjectured  that  this  black  matter  was  nothing  more 
than  carbon  :  several  experiments  appeared  to  confirm  this  opinion,  but  it  is  now  gen- 
erally believed  to  be  formed  by  the  colouring  matter  of  the  blood.*  In  the  European  it 
escapes  observation,  because  it  does  not  differ  much  in  colour  from  the  epidermis  and 
dermis. 

The  colour  of  the  skin,  which  is  a  matter  of  such  interest  in  the  natural  history  of 
mankind,  and  which  forms  one  of  the  principal  characters  of  the  several  human  races, 
has  a  tolerably  constant  relation  to  the  colour  of  the  hair :  thus,  individufds  with  light 
hair  have  generally  fairer  skins  than  such  as  have  dark  hair ;  and  thus,  also,  red  hair  is 
accompanied  with  a  somewhat  analogous  colour  of  the  skin.  In  albinoes  the  colouring 
matter  is  deficient  in  the  skin,  as  it  is  in  the  hair,  and  in  the  interior  of  the  eye.  More- 
over, the  transition,  in  regard  to  the  colour  of  the  skin,  from  the  white  to  the  black  races 
of  mankind,  occurs  through  a  succession  of  intermediate  shades  :  thus,  I  have  found  a 
colouring  matter  precisely  similar  to  that  of  the  negro's  skin  beneath  the  epidermis  of 
several  Europeans,  particularly  upon  the  scrotum,  and  upon  the  tanned  faces  of  those 
who  have  lived  exposed  to  a  strong  solar  heat.  In  the  disease  called  black  or  green 
jaundice,  the  skin  of  white  persons  becomes  black  or  olive-coloured.  A  superficial 
chronic  irritation  produced  by  blisters,  or  certain  skin  diseases,  or  by  an  adjacent  wound, 
will  also  sometimes  cause  a  black  discoloration  of  the  skin. 

•  As  to  the  source  of  the  pigment  of  the  skin,  it  is  thought  by  M.  Gauthier  that  it  is 
yielded  by  the  bulbs  of  the  hairs.  M.  Breschet  describes  a  series  of  glandular  organs  for 
secreting  this  pigment,  which,  according  to  him,  are  situated  in  deep  furrows  in  the 
outer  portion  of  the  dermis,  and  are  surmounted  by  a  great  number  of  excretory  tubes, 
from  which  the  globules  of  pigment  are  poured  out  beneath  the  epidermis.  I  have  never 
been  fortunate  enough  to  ascertain  the  existence  of  these  glandular  organs  and  their  ex- 
cretory tubes.  It  is  generally  supposed  that  the  vessels  of  the  cutaneous  papillae  are  the 
source  whence  the  pigment  is  derived  ;  the  mechanism  of  its  formation  must  be  the 
same  as  that  of  the  formation  of  the  choroid  pigment  in  the  eye,  and  it  is  quite  as  little 
understood.* 

The  Epidermis. — The  epidermis,  or  cuticle  (J,  fig.  226  ;  a  b,  fig.  227),  is  the  outermost 
of  the  several  layers  of  the  skin  ;  it  is  a  semi-transparent,  homy  layer,  which  is  moulded 
upon  the  surface  of  the  dermis  and  its  papillae  like  a  coat  of  varnish,  and  protects  them 
from  the  action  of  external  agents.  Its  internal  surface  is,  in  fact,  marked  by  a  multi- 
tude of  little  pits,  into  each  of  which  a  papilla  is  received  ;  so  that  this  surface  of  the 
epidermis  may  be  said  to  form  a  mould  of  the  papillary  surface  of  the  skin.  In  the  skin 
of  the  negro,  the  colouring  matter  occupies  the  little  pits  in  the  epidermis,  and  is  found 
in  greater  abundance  between  the  papillae  than  upon  them. 

In  order  to  obtain  a  good  view  of  the  structure  of  the  internal  surface  of  the  epidermis, 
various  sections  may  be  made  of  the  skin  upon  the  palms  of  the  hands  and  soles  of  the 
feet.  It  will  then  be  seen  that  the  papillas  dip,  as  it  were,  into  the  epidermis,  which  fur- 
nishes a  kind  of  sheath  for  each  of  them.  This  arrangement  is  exceedingly  distinct  in 
the  skin  upon  the  lower  surface  of  the  bear's  foot.  I  have  alluded  to  this  structure  in 
vay  Anatomie  Pathologique  (-'Diseases  of  the  Lymphatics,"  liv.  ii.).  M.  Breschet  has 
recently  observed  it  in  the  skin  of  the  whale,  in  which  animal  the  epidermis  forms  a 
complete  tube  for  each  of  the  papillae.  These  sheaths,  or  tubes,  are  united  by  a  gluti 
nous  matter,  and  may  be  separated,  at  least  in  the  bear,  with  the  greatest  facility. 

The  internal  surface  of  the  epidermis  is  intimately  adherent  to  the  external  surface  oi 
the  dermis  ;  but  this  adhesion  may  be  destroyed  in  the  living  subject  by  the  application 
of  a  blister,  and  after  death  by  maceration.  If  in  a  piece  of  macerated  skin  the  epider- 
mis be  carefully  separated  from  the  true  skin,  it  will  be  seen  that  the  adhesion  of  one  to 
the  other  is  in  part  effected  by  a  number  of  very  delicate  transparent  filaments,  which 
may  be  stretched  to  the  extent  of  several  lines  without  breaking.  On  examining  the  in- 
ternal surface  of  the  epidermis  imder  water,  these  filaments  are  seen  floated  out. 

What,  then,  is  their  nature  1  Are  we  to  regard  them,  with  Cruickshank,  as  prolonga- 
tions of  the  epidermis  which  dip  into  the  areolae  of  the  true  skin"!  or,  with  Beclard,  as 
strings  of  mucus  formed  by  the  stretching  out  of  the  viscid  mucous  matter  situated  be- 
tween the  dermis  and  the  epidermis  1  or,  on  the  other  hand,  are  they  canals  1  and  if  so, 
are  they  to  be  regarded  as  exhalant  vessels,  as  Kaaw,  Boerhaave,  and  W.  Hunter  be- 
lieved'? are  they  exhalant  and  absorbent  vessels  too,  as  Chaussier  and  Bichat  imagined? 
or  are  they  not,  rather,  special  vessels,  the  vasa  sudoris  of  Bidloo,  and  the  vasa  sudatoria 
of  Eichhorn,  the  latter  of  whom  attributed  to  them  both  an  exhalant  and  an  absorbent 
function  1  These  questions  are  not  yet  satisfactorily  solved.  The  very  great  activity, 
both  of  exhalation  and  absorption  of  the  skin,  necessarily  supposes  the  existence  of  some 
special  apparatus  for  these  processes. 

Steno,  Malpighi,  and  others  admitted  the  existence  of  certain  sudoriferous  glands,  sit- 
uated in  the  adipose  cellular  tissue,  and  consisting  of  tubes  which  opened  on  the  exte- 

*  See  note,  p.  635 

4L 


634  NEUROLOGY. 

rior  by  means  of  an  orifice  provided  with  a  valve.    (Vide  Holler,  t.  v.,  lib.  xii.,  p.  42.) 
Fig.  227.  Th.\s  description,  when  somewhat  modified,  agrees  with  the 

statements  recently  made  by  M.  Breschet,  who  has  described 
sudoriferous  glands  {g  g,  figs.  227,  228)  having  a  saccular  form, 
and  situated  in  the  substance  of  the  dermis.  A  spiral  canal* 
(h,  fig.  227),  proceeding  from  each  of  these  sacs,  traverses  the 
dermis  and  epidermis,  and,  after  having  made  several  turns, 
opens  upon  the  external  surface  of  the  skin  (at  i).t 

Besides  these  filaments,  the  deep  surface  of  the  epidermis 
presents  certain  irregularities,  which  may  be  felt  by  the  finger, 
and  which,  under  the  microscope,  appear  pointed  like  thorns  ; 
they  seem  to  be  prolongations  of  the  epidermis,  but  I  have  not 
been  able  to  detennine  their  precise  nature. 

The  external  surface  of  the  epidermis  presents  corresponding 
folds  and  furrows  to  those  already  described  upon  the  free  sur- 
face of  the  skin.  It  also  has  numerous  orifices  or  pores,  visi- 
ble to  the  naked  eye  on  the  palms  of  the  hands  and  soles  of 
the  feet,  and  very  distinctly  seen  by  the  aid  of  a  lens.  Along 
each  of  the  ridges  formed  by  the  rows  of  papillae  are  found  a 
series  of  orifices,  arranged  in  a  regular  manner,  and  resem- 
bling in  appearance  the  puncta  lachrymalia  in  the  eyelids.  If 
the  skin  be  examined  with  a  lens  during  life,  while  the  person 
is  perspiring,  drops  of  the  excreted  fluid  are  seen  to  exude, 
and  form  into  a  small  globule,  which  is  soon  lost  by  evaporation, 
and,  after  a  few  seconds,  another  globule  makes  its  appearance. 
It  is  impossible  to  conceive  how  several  celebrated  anatomists  could  have  denied  the 
existence  of  pores  in  the  skin.  J 

Delia  Torre,  Fontana,  and  Mascagni  believed  that  the  epidermis  was  organized,  and 
that  it  consisted  of  a  network  of  lymphatic  vessels.  But  as  Panizza  has  clearly  proved 
(Osservazioni  Antropo-zootomico  Fisiologiche,  1830,  p.  83),  the  lymphatic  network  always 
lies  beneath  the  epidermis,  which  may,  by  maceration,  be  raised  up  from  it.  After  the 
example  of  Panizza,  I  have  endeavoured  to  inject  the  epidermis  upon  the  soles  of  the 
feet,  and  upon  other  parts  of  the  body,  but  without  being  able  to  find  a  single  vessel. 
As  for  the  opinion  that  the  epidermis  contains  arterial  and  venous  capillaries,  it  is  so  at 
variance  with  the  results  of  observation  that  it  does  not  require  refutation.  The  epi- 
dermis, then,  is  unorganized  [non-vascular]. 

It  is  a  product  of  secretion,  a  layer  of  concrete,  transparent,  and  very  hygrometric 
mucus  ;  a  sort  of  horny  matter,  of  variable  thickness,  capable  of  reproduction  after  hav- 
ing been  destroyed,  and  the  morbid  alterations  of  which  result,  not  from  any  proper  vital 
action  in  itself,  but  from  a  diseased  condition  of  those  living  parts  of  the  skin  by  which 
it  seems  to  be  produced. 

As  to  the  structure  of  the  epidermis,  it  has  been  repeatedly  stated  to  consist  of  imbri- 
cated scales  ;  but  the  most  careful  examination  discloses  nothing  more  than  a  layer  ol 
uniform  structure,  into  which  the  papillae  enter ;  so  that  it  may  be  decomposed,  hypo- 
thetically  and  even  actually,  by  the  aid  of  the  scalpel,  in  some  animals,  into  a  number  of 
agglutinated  tubes  or  sheaths,  each  of  which  belongs  to  a  single  papilla.  The  different 
forms  of  the  fragments  of  epidermis,  detached  either  spontaneously  or  in  consequence  of 
disease,  depend  upon  accidental  circumstances,  and  show  the  continuity  of  this  mem- 
brane in  the  human  subject.^  I  shall  presently  describe  the  relations  of  the  epidermis  to 
the  hair,  the  nails,  and  the  sebaceous  follicles. 

*  Fontana  had  previously  spoken  of  serpentine  vessels,  which  he  had  seen  beneath  the  epidermis  by  meaua 
of  the  microscope. 

+  [The  sudoriferous  glands,  discovered  by  Breschet,  Purldnj6,  and  Wendt,  may  be  seen  best  by  examining 
under  the  microscope  a  thin  perpendicular  section  of  a  piece  of  skin  taken  from  the  palm  of  the  hand  (as  ia 
fig.  227),  and  hardened  in  a  solution  of  carbonate  of  potash.  They  are  situated  in  the  sub-cutaneous  adipose 
cellular  tissue  (/) ;  they  consist  of  a  long  convoluted  tube  (or  of  two  tubes  which  unite  together),  ending  in  an 
efferent  duct  (A),  which  opens  (i)  upon  the  free  surface  of  the  epidermis,  and  is  lined  by  flattened  epidermic 
corpuscules.  Where  the  epidermis  is  thin,  these  ducts  are  nearly  straight,  as  in  the  scalp  (see  Jig.  228),  and 
their  orifices  are  scattered  irregularly  over  the  surface  ;  where  it  is  thick,  they  have  a  spiral  course,  as  in  the 
palm  and  sole  (fig.  227),  where  their  orifices  are  arranged  in  single  rows  on  the  papillary  ridges.  These  spi- 
ral ducts  are  turned  in  opposite  directions  on  the  right  and  left  extremities  ;  the  average  number  of  their  ori- 
fices is  fifty  in  the  square  line  ;  the  filaments  described  in  the  text  as  connecting  the  epidermis  to  the  dermis 
are  the  epidermic  linings  drawn  out  of  these  ducts,  and  out  of  the  sebaceous  and  piliferous  follicles.] 

i  See  note,  p.  supra. 

[^  The  epideiTuic  portion  of  the  skin  has  been  so  long  supposed  to  consist  of  several  distinct  structures,  that 
it  is  still  convenient  to  describe  separately  an  epidermis,  a  pigmentum,  and  a  rete  mucosuni ;  but  modern  re- 
search has  shown  that  these  are  merely  different  layers  of  the  same  structure,  in  different  stages  of  develop- 
ment. The  most  superficial  and  hardest  of  these  layers,  which  is  separated  from  the  skin  in  vesication  during 
life,  and  by  maceration  after  death,  is  the  epidermis  described  in  the  text,  and  by  authors  generally  ;  the 
deeper,  more  recently  formed,  and  softer  portions,  which  may  be  displayed  and  subdivided  into  several  layers 
by  maceration  and  dissection,  constitute  the  pigmentum  and  the  rete  mucosum :  together,  these  insensible, 
extra-vascular,  but  not  inorganic  layers,  form  what  is  now  called  the  epidermis. 

Thus  defined,  the  epidermis  exactly  resembles  the  epithelium  of  mucous  membranes,  in  consisting  of  a 
number  of  adherent  nucleated  corpuscules,  each  of  which  undergoes  an  independent  development.     Ininiedi 


APPENDAGES    OF    THE    SKIN.  '"635 

According  to  M.  Breschet,  certain  minute  reddish  glands  are  situated  among  the  sub- 
cutaneous adipose  vesicles,  and  constitute  the  secreting  apparatus  of  the  epidermis.  Ex- 
cretory ducts  are  said  by  him  to  proceed  from  the  summits  of  these  small  glands,  to  trav- 
erse the  dermis,  and  to  open  at  the  bottom  of  the  furrows  found  upon  its  external  sur- 
face. According  to  the  same  observer,  these  ducts  generally  resemble  rows  of  regular- 
ly-arranged columns,  and  the  glands  are  sometimes  situated  at  unequal  depths  from  the 
surface,  and  communicate  with  each  other  by  intermediate  ducts.  I  have  never  suc- 
ceeded in  verifying  these  observations  ;  and  I  have  equally  failed  in  attempting  to  decom- 
pose the  epidermis  into  a  series  of  layers,  becoming  less  and  less  compact  in  proportion 
to  their  distance  from  the  surface. 

The  Corpus  Mucosum,  or  Corpus  Reticulaire  of  Malpighi. — Malpighi  applied  the  term 
reticulum,  and  others,  following  that  great  anatomist,  have  given  the  names  corpus  retic- 
ulaire, corpus  mucosum,  and  rete  mucosum,  to  a  gelatiniform  layer  {d,  fig.  227)  of  what  is 
regarded  as  a  concrete  mucus,  situated  beneath  the  epidermis  and  perforated  by  the  pa- 
pillae, which  thus  give  it  a  reticulated  appearance.  This  inorganic  [non-vascular]  layer, 
which  Malpighi  first  demonstrated  beneath  the  thick  epithelium  of  the  tongue  of  the  ox, 
after  it  had  been  boiled,  and  which  he  then  supposed  to  exist  also  in  the  skin,  cannot  be 
demonstrated  anatomically ;  so  that  the  expressions  corpus  mucosum,  corpus  reticulaire, 
have  lost  their  original  signification,  and  have  been  interpreted  in  a  different  sense. 
Haller,  and  several  anatomists  quoted  by  him,  regarded  the  corpus  mucosum  as  a  deep 
layer  of  the  epidermis,  some  of  them  confounding  it  with  the  pigmentum,  and  others  dis- 
tinguishing it  from  that  body.  Bichat  considered  the  corpus  mucosum  to  be  an  extreme- 
ly delicate  network  of  vessels,  or  system  of  capillaries,  which  formed,  with  the  papillae, 
an  intermediate  layer  between  the  chorion  and  epidermis,  and  was  partly  intended  to 
convey  the  blood,  and  partly  the  colouring  matter  of  the  skin. 

M.  Gauthier,  in  examining  the  skin  of  the  heel  in  the  negro,  recognised  four  distinct 
layers  in  the  corpus  mucosum,  arranged  in  the  following  manner,  from  within  outward  : 
1.  Vascular  processes  containing  red  blood  {bourgeons  sanguins),  which  are  situated  upon 
and  adhere  to  the  papillae  ;  2.  A  deep  white  layer,  composed  of  serous  vessels,  and 
moulded  upon  the  vascular  processes  and  papillae  ;  3.  A  layer  of  gemmules,  forming  a 
kind  of  coloured  membrane,  excavated  upon  its  deep  surface,  and  separated  from  the 
vascular  processes  and  papillae  by  the  deep  white  layer  ;  4.  A  superficial  white  layer, 
which  he  regards  as  formed  of  serous  vessels,  as  well  as  the  deep  white  layer.  Exter- 
nally to  this  is  the  epidermis.  M.  Dutrochet,  founding  his  opinion  upon  the  examination 
of  the  skins  of  quadrupeds,  admits  the  different  layers  of  M.  Gauthier,  excepting  the  vas- 
cular processes,  which  he  very  properly  regards  as  forming  parts  of  the  papillfe  :  he 
calls  the  deep  white  layer  of  M.  Gauthier  the  epidermic  inembrane,  the  gemmules  he  terms 
the  coloured  layer,  and  the  superficial  white  layer  he  names  the  horny  layer. 

Lastly,  Gall  regarded  the  corpus  mucosum  as  a  layer  of  gray  nervous  matter,  precisely 
similar  to  that  of  the  gray  substance  of  the  brain  and  of  the  nervous  ganglia. 

I  agree  with  Chaussier  that  we  ought  altogether  to  reject  the  corpus  mucosum,  in 
whatever  sense  that  term  may  be  understood  ;  and  I  believe  there  are  good  grounds  for 
supposing  that  the  different  layers  described  as  forming  this  body  belong,  in  reality,  some 
to  the  papillae,  and  others  to  the  epidermis.* 

Appendages  of  the  Skin. 

Under  this  title  may  be  included  the  sebaceous  follicles  and  the  homy  growths,  viz., 
the  nails  and  hairs. 

The  Sebaceous  Follicles. — The  skin  contains  within  its  substance  certain  sebaceous  fol- 
licles {i  i,  fig.  228) ;  these  consist  of  small  pouches,  or  bags,  about  the  size  of  a  millet 
seed,  which  form  projections  beyond  the  epidermis,  but  are  lodged  in  the  substance  of  the 
dermis,  and  open  externally  by  very  small  orifices,  which  are  visible  under  a  lens,  and, 
in  some  persons,  even  to  the  naked  eye.  From  these  orifices  an  unctuous  matter  is  con- 
stantly poured  out  upon  the  surface  of  the  skin,  and  assists  in  preserving  its  pliability ; 
in  some  individuals  this  unctuous  matter  may  be  expressed  from  the  follicles  upon  the 

ately  upon  the  surface  of  the  true  skin,  these  corpuscules  are  soft,  roundish  vesicles,  containing  a  distinct  nu- 
cleus and  peculiar  pigment  granules,  and  adhering  together  by  a  viscid  matter,  the  cytoblastema,  in  which 
they  are  first  developed.  In  approaching  the  surface  of  the  cuticle,  they  become  larger  and  more  compressed, 
their  walls  become  thicker  and  denser,  their  nuclei  less  distinct,  and  their  pigment  paler,  until,  at  length,  they 
form  thethin,  flattened,  horny,  nucleated,  colourless  discs,  whicli,  adhering  to  each  other  firmly  in  an  imbricated 
manner,  constitute  the  upper  and  horny  portion  of  the  epidermis,  from  the  free  surface  of  which  they  are  con- 
stantly being  thrown  off  as  minute  scales,  to  be  continually  replaced  by  others  having  a  similar  origin,  and  un- 
dergoing the  same  changes  :  these  imbricated  scales  were  described  by  Leuwenhoek  and  Baker. 

The  epidermis  is  insoluble,  even  in  boiling  water  ;  but  it  swells  and  becomes  softened  and  transparent,  in 
these  respects  resembling  mucus  and  epithelium  ;  it  consists  of  a  substance  called  keratin. 

The  pigment  granules  contained  in  the  deeper  epidermic  corpuscules  are  the  cause  of  the  colour  in  the 
skin ;  they  are  black  in  the  negro,  &c.,  of  lighter  hues  in  other  dark  races,  and  fawn-coloured  in  the  Euro- 
pean ;  in  all  cases  they  are  darlcest  in  the  deeper  and  newly-formed  corpuscules,  and  fade  as  these  approach 
the  surface  :  in  albinoes  they  are  either  absent  or  colourless.  The  pigment  contains  iron  and  carbon,  both  in 
a  combined  state,  phosphate  of  lime,  and  animal  matter  ;  but  as  it  is  bleached  by  chlorine,  it  contains  no  free 
carbon,  as  supposed  by  some.] 

*  See  note,  p.  634. 


636 


NEUROLOGY. 


Section  of  skin  from  the  head, 
magnified  14  times. 


Fig.  228.  alae  of  the  nose,  in  masses  which  look  like  small  worms. 

These  sebaceous  follicles  are  somewhat  analogous  to 
the  follicles  of  the  mucous  membranes  ;  they  are  not 
found  in  the  palms  of  the  hands  and  soles  of  the  feet ; 
but,  in  all  probability,  they  exist  in  every  part  of  the 
body  :  they  are  especially  observed  in  the  axilla,  on  the 
hairy  scalp,  and  around  the  margins  of  the  anus  and 
vulva,  and  the  openings  of  the  nose  and  mouth  :  they 
are  very  much  developed  in  the  new-bom  infant.  The 
sebaceous  follicles  appear  to  me  to  have  a  glaiidular 
structure  ;  and  this  is  particularly  evident  in  those  of 
the  axilla,  the  organization  of  which  seems  to  me  to  be 
more  complex  than  that  of  those  found  in  other  parts 
The  supposition  that  these  follicles  are  formed  by  the 
reflection  of  the  thin  portion  of  the  skin  is  altogether 
fanciful.* 

The  Nails  and  the  Hair. — In  man  the  horny  growths 
of  the  skin  are  less  developed  than  in  any  animal  expo- 
sed to  similar  atmospheric  conditions  ;  and  in  man,  also, 
we  find  the  highest  development  of  the  sense  of  touch. 
The  nails  of  the  human  subject  are  hard,  yet  flexible 
and  elastic,  semi-transparent  scales,  and  present  the  ap- 
pearance of  laminae  of  horn  :  they  are  situated  upon  the  dorsal  surface  of  the  last  phalan- 
ges, which  are  therefore  called  the  ungual  phalanges ;  and  they  appear  rather  to  be  in- 
tended for  the  support  and  protection  of  the  pulpy  extremities  of  the*ngers.  than  as  weap- 
ons of  attack,  or  instruments  of  defence  and  prehension.  In  a  state  of  civilization  it  is 
customary,  therefore,  to  cut  ofl!'that  part  of  the  nail  which  projects  beyond  the  end  of  the 
finger.  The  ingenuity  of  man  enables  him  to  provide  himself  with  oflfensive  M^eapons 
amply  sufficient  to  compensate  for  the  weakness  of  those  provided  by  nature,  which,  in- 
deed, are  quite  rudimentary  in  him,  and  if  more  fiilly  developed,  would  greatly  interfere 
with  the  delicacy  of  his  sense  of  touch. 

The  peculiarity  of  the  human  nail  consists  in  its  only  covering  the  dorsal  surface  of  the 
last  phalanx,  and  in  its  being  of  considerable  breadth,  corresponding,  in  this  respect,  with 
the  horseshoe-like  enlargement  at  the  end  of  the  phalanx.  It  follows  from  this,  that  the 
whole  of  the  pulp  of  the  finger  is  concerned  in  the  exercise  of  the  sense  of  touch,  t 

The  nail  is  divided  into  the  root,  the  body,  and  the  free  portion  :  the  root  is  that  part  of 
the  nail  which  is  covered  on  both  surfaces ;  the  body  is  that  part  which  has  one  sur- 
face free  ;  while  the  third,  or  entirely /rec  portion,  projects  beyond  the  end  of  the  finger, 
and  has  a  tendency  to  become  incurvated  when  left  to  grow  naturally. 

In  order  to  obtain  a  correct  idea  of  the  anatomy  of  the  nails,  we  should,  by  a  longitu 
dinal  incision,  make  a  vertical  section  of  the  ungual  portion  of  one  of  the  fingers  (see  fig. 
229).  We  shall  then  perceive  that  the  root  is  about  one  fourth  of  the  length  of  the  body 
of  the  nail  (J) ;  that  it  is  also  the  thinnest  part  of  the  nail ;  that  it  diminishes  in  thick- 
ness towards  its  posterior  edge,  which  is  slightly  indented,  and  that  it  increases  towards 
the  body  of  the  nail ;  that  it  is  flexible,  and  is  received  into  a  duplicature  of  the  skin  (c 
c),  to  which  it  is  attached  by  both  surfaces  ;  that  the  posterior  edge  and  lower  surface  of 
the  root  adhere  so  slightly  to  the  skin,  that  they  may  be  said  to  be  merely  applied  to  it ; 
that  the  upper  surface  of  the  root,  though  it  adheres  more  closely  to  the  skin  than  the 
lower  surface,  is  yet  much  less  firmly  attached  to  it  than  the  under  surface  of  the  body 
of  the  nail,  which  cannot  be  torn  off  without  great  violence  ;  that  the  nail  is  separated 
from  the  phalanx  by  a  very  thick  dermis  (c') ;  that  this  skin  is  of  a  white  colour  at  the 
root  of  the  nail,  and  for  some  distance  in  front  of  it,  where  it  occasions  a  semilunar 
white  mark,  visible  through  the  transparent  nail,  and  called  the  lunule  (lunula) ;  and,  lastly, 
that  the  dermis,  which  corresponds  to  the  body  of  the  nail,  is  extremely  vascular,  and 
hence  the  nail  has  a  rosy  hue,  because  its  semi-transparency  enables  us  to  perceive  the 
colour  of  the  subjacent  tissue. 

One  of  the  most  important  points  in  the  anatomy  of  the  nail  is  the  nature  of  its  con- 
nexion with  the  dermis.  The  fold  of  the  skin,  which  is  called  the  matrix  of  the  nail,  is 
Ibrmed  in  the  following  manner :  the  skin  (c,  fig.  229,  being  the  dermis)  is  prolonged 

*  [The  sebaceous  glands  (t't,  _/5^.  228)  are  mtiltilocular  follicles;  their  ducts  are  lined  by  epi.lennic  cor- 
puscules,  and  open  upon  the  surface  of  the  skin  in  parts  without  hairs  ;  where  hairs  exist,  they  open  into  the 
hair  follicles  (c),  to  each  of  which  two  sebaceous  glands  (it)  are  generally  attached.  On  the  face,  very  nii- 
B^ite  hairs  have  been  found  around  the  orifices  of  the  ducts  of  these  glands :  their  secretion  is  albuminous  as 
well  as  fatty.] 

t  The  hoof,  of  which  a  very  perfect  example  is  met  in  the  horse,  is  nothing  more  than  a  nail  which  enclo- 
ses the  united  phalanges  on  all  sides,  like  the  wooden  shoes  sometimes  worn  ;  the  claw  of  carnivorous  animals 
is  a  nail  which  covers  two  thirds  of  the  slender  ungual  phalanx,  is  compressed  at  the  sides,  and  terminates  in 
a  pointed  hook.  The  nail,  properly  so  called,  is  found  only  in  man  and  in  quadrumana,  and  in  the  latter  it 
approaches  in  ch.aracter  to  the  claw.  The  division  of  mammalia  into  ungulatcd  and  unsrniciila'pd  is  exceed- 
ingly natural,  and  is,  in  some  measure,  represented  by  certain  correlative  and  constant  differences  in  all  other 
Darts  of  the  system. — (See  Anatomic  Comparee  de  M.  de  Jilainville.) 


THE    APPENDAGES   OF   THE   SKIN.  $^ 

from  the  finger  on  to  the  dorsal  suiface  of  the  nail,  as  far 
as  the  curved  line  that  marks  the  posterior  boundary  o! 
the  body  of  the  nail ;  from  thence  it  is  reflected  b;ick- 
ward,  folded  upon  itself,  as  far  as  the  posterior  bonlrr 
of  the  root  of  the  nail.  At  this  point  it  is  again  reflected 
forward  upon  itself  by  passing  behind  that  border,  and 
then  (c'  c')  between  the  under  surface  of  the  nail  and  th'i 
dorsal  aspect  of  the  phalanx :  in  consequence  of  this  two- 
fold reflection,  it  follows  that  it  is  always  the  epidennic  ^"''°"  "'"'='"  "^  *"»'• 
surface  of  the  true  skin  that  is  in  contact  with  the  nail :  at  the  anterior  extremity  of  the 
nail  the  skin  again  meets,  as  it  were,  the  epidermis  (a'),  and  becomes  continuous  with 
the  integument  upon  the  tip  of  the  finger.  But  what  is  the  arrangement  of  the  epider- 
mis at  the  point  where  the  skin  is  first  reflected  backward  1  It  is  prolonged  forward 
(a),  slightly  beyond  the  curved  line  formed  by  the  reflection  of  the  dermis,  and  forms  a 
semicircular  zone  or  band,  which  terminates  by  a  smooth  border,  and  jidheres  intimately 
to  the  nail.  As  to  its  arrangement  beyond  this  point  authors  are  not  agreed.  Some  are 
of  opinion  that  it  would  be  prolonged  upon  the  free  surface  of  the  nail,  if  it  were  not  de- 
stroyed by  friction  ;  but  they  overlook  an  objection  to  this  view  to  be  derived  from  the 
accustomed  regularity  of  the  epidermic  border :  others,  again,  believe  that  the  epidermis 
is  reflected  backward  like  the  dermis,  but  differ  among  themselves  cis  to  its  ultimate  dis 
position ;  some,  for  example,  conceiving,  with  Bichat,  that  tlie  epidermis  is  continuous 
with  the  posterior  border  of  the  nail,  and  some  supposing  that  it  is  again  reflected  for 
ward  beneath  the  nail,  together  with  the  dermis  (see  dotted  line),  which,  according  to 
this  hypothesis,  it  never  quits.* 

A  very  simple  experiment  most  clearly  demonstrates  the  nature  of  the  connexion  be- 
tween the  epidermis  and  the  nail :  it  consists  in  submitting  a  finger  to  the  process  of 
maceration,  by  means  of  which  the  nail  and  epidermis  come  off  together  in  the  form  of 
a  partly  epidermic  and  partly  horny  sheath.  In  this  the  epidermis  (a)  is  found  to  be  re- 
flected backward  upon  the  dorsal  surface  of  the  root  of  the  nail,  and  to  become  blended 
with  it  (see  fig.  229)  without  ever  passing  beyond  its  posterior  border ;  while  in  front,  at 
the  limits  between  the  body  and  the  free  portion  of  the  nail,  the  epidermis  (a')  is  mani- 
festly continuous  with  the  deepest  layer  of  the  homy  lamina ;  so  that  it  cannot  be  doubt- 
ed that  there  is  an  identity  of  nature  between  the  nail  and  epidermis. 

Structure  and  Growth  of  the  Nail. — On  examining  the  two  surfaces  of  the  nail,  and  es- 
pecially its  deep  surface  and  posterior  border,  it  is  found  that  they  are  marked  by  very 
distinct  longitudinal  lines  or  striae,  which  appear  to  indicate  a  corresponding  linear  tex- 
ture. It  would  seem,  accordingly,  that  the  nail  was  formed  by  the  agglutination  into 
laminae  of  a  number  of  longitudinal  fibres  ;  but,  if  we  examine  the  free  surface  of  the  nail 
attentively,  we  find  that  it  is  marked  by  curved  striae,  which  intersect  the  longitudinal 
ones.  These  curved  striae  are  particularly  distinct  in  the  not  uncommon  cases  in  which 
the  nail  of  the  great  toe  is  much  hypertrophied,  and  becomes  incurvated  upon  the  plantar 
surface  of  the  toe  :  the  enlarged  nail  is  found  to  consist  of  imbricated  laminae,  received 
one  into  the  other  like  the  several  laminae  in  the  hoof  of  an  animal.  We  may  even  sep- 
arate these  different  layers  by  aid  of  maceration,  and  find  that  they  are  fitted  one  into 
the  other,  the  deepest  being  that  which  was  last  secreted.  The  nails,  therefore,  are 
developed  by  a  method  very  analogous  to  that  by  which  we  have  already  stated  the  teeth 
are  formed.    (See  p.  179.) 

The  nails,  then,  like  the  hoofs  of  animals,  and  like  the  epidermis,  are  products  of  se- 
cretion :  they  receive  neither  vessels  nor  nerves  :  alterations  in  their  texture  are  not  de- 
pendant upon  diseases  inherent  in  themselves,  but  result  from  some  morbid  condition  of 
their  formative  organ.  The  fold  of  the  dermis,  which  is  called  the  matrix  of  the  nail,  is 
not  the  only  part  by  which  the  substance  of  the  nail  is  secreted,  but  the  whole  papillary 
surface  of  the  dermis,  to  which  the  nail  adheres,  is  concerned  in  its  formation.  The 
papillae  are  ananged  in  longitudinal  rows,  and  hence  the  substance  of  the  nail  is  depos- 
ited in  longitudinal  striae. -f 

The  nail  grows  continually  in  length ;  it  does  not  increase  sensibly  in  thickness,  ex- 
cepting during  disease.  The  layers  that  have  been  deposited  the  longest  time  are  the 
most  superficial,  and  occupy  the  free  extremity  of  the  nail,  in  precisely  the  same  manner 
as  the  oldest-formed  ivory  in  the  tooth  is  nearest  to  the  enamel.t 

*  See  note  t,  below. 

f  The  arrangement  of  the  papillary  dermoid  layer  which  covers  the  dorsal  surface  ot  the  ungual  phalanx 
IS  worthy  of  notice  :  it  adheres  intimately  to  the  periosteum,  and  forms  an  extremely  dense,  grayish  stratum, 
penetrated  by  vessels  and  nerves  ;  so  that,  if  the  mode  of  termination  of  the  nerves  in  the  papillse  c.an  ever  be  as- 
certained, it  is,  without  doubt,  beneath  the  nail,  where  these  papillae  present  their  highest  state  of  development. 

t  [The  nails  are  found  by  Schwann  to  consist  of  nucleated  corpuscles,  which,  like  those  of  the  epidermis, 
are  formed  upon  the  surface  of  the  dermis,  where  they  are  soft  and  vesicular,  and  afterward  become  hard, 
flattened,  and  firmly  agglutinated  together,  as  in  the  substance  of  the  nail.  These  corpuscles  are  developed, 
not  only  opposite  the  matrix  of  the  nail,  but  beneath  the  whole  of  its  attached  surface  ;  the  nail  is  thus  elon- 
gated, and,  at  the  same  time,  its  thickness  is  maintained,  notwithstanding  the  flattening  of  the  corpuscles 
formed  at  the  root  as  they  approach  the  surface.  The  thin  layer  of  epidermis,  described  by  Weber,  Lauth, 
and  Gurlt,  as  continued  under  the  whole  attached  surface  of  the  nail,  is  nothing  more  than  the  soft  stratum 
of  growing  corpuscles,  which  pass  insensibly  into  those  of  the  true  epidermis. 

Like  the  epidermis,  the  nails  consist  of  keratin.} 


638  NEUROLOGY. 

The  Hairs. — The  hairs  are  filiform  productions  of  tiie  epidermis,  generally  flexible,  va- 
riable in  length,  size,  and  colour,  and  bearing  different  names,  according  to  the  region  on 
which  they  are  situated.* 

The  surface  of  the  human  body,  with  the  exception  of  the  palms  of  the  hands  and  the 
soles  of  the  feet,  is  covered  by  very  fine  and  short  hairs,  which  form  a  light  down,  as  it 
is  named  ;  but  the  hairs,  properly  so  called,  are  collected  upon  particular  parts  of  the  sur- 
face of  the  body,  where  they  serve  some  special  purpose.  Thus,  they  exist  in  great 
abundance  upon  the  cranium,  where  they  are  called  the  hair ;  on  the  face,  where  they 
form  the  whiskers  and  beard ;  the  hairs  upon  the  margins  of  the  eyelids  are  called  the  eye- 
lashes ;  the  arched  row  over  each  orbit  is  called  the  eyebrow ;  the  hairs  upon  the  lips  con- 
stitute the  mustache. 

On  the  trunk  the  hairs  are  collected,  in  more  or  less  abundance,  around  the  genital  or- 
gans :  they  exist,  also,  in  the  axillae  of  both  sexes  ;  and  on  the  chest,  between  the  breasts, 
in  the  male.  The  hairs  present  well-marked  differences,  according  to  sex,  age,  and  the 
peculiar  race  to  which  the  individual  belongs.  The  pilous  system  is  most  developed  in 
the  Caucasian  race,  and  least  so  in  the  negro. 

The  hair,  eyelashes,  and  eyebrows  exist  before  birth :  before  birth,  also,  the  whole 
body  is  clothed  with  a  very  thick  down,  which  is  shed  during  the  first  few  months  after- 
ward. At  the  period  of  puberty,  hairs  are  developed  upon  the  pubic  region,  and  in  the 
axillae  of  both  sexes,  upon  the  labia  majora  of  the  female,  and  upon  the  scrotum  and 
around  the  anal  orifice  in  the  male  :  the  beard  also  appears  in  the  male,  and  the  ante- 
rior aspect  of  the  trunk,  and  the  limbs  are  covered  with  hairs  of  variable  length  in  dif- 
ferent persons.  I  should  observe,  that  the  development  of  the  hairs  is  not  always  in 
proportion  to  the  personal  strength,  as  is  asserted  by  certain  authors,  who  regard  an 
abundance  of  hair  as  an  attribute  of  strength  and  virility.  But,  although  some  men  with 
hairy  skins  have  robust  constitutions,  a  great  number  are  delicate,  and  are  even  affected 
with  tubercular  phthisis. 

In  mammalia,  the  hairs  upon  the  posterior  or  dorsal  region  of  the  trunk  are  more  de- 
veloped than  those  upon  the  anterior  or  abdominal  aspect,  a  proof  that  they  are  destined 
to  the  quadruped  attitude :  in  some  animals,  which  turn  upon  their  backs  to  protect  them- 
selves, the  hairs  upon  the  abdominal  surface  are  most  highly  developed. 

The  hair  of  the  head  may  grow  to  a  very  considerable  length :  it  has  been  seen  to  reach 
as  low  down  as  the  middle  of  the  leg,  and,  when  thrown  around  the  trunk,  sufficiently 
abundant  to  cover  it  like  a  garment.  The  length  and  the  direction  of  the  hair  upon  the 
head  evidently  prove  that  man  is  destined  for  the  erect  posture  ;  for,  if  he  assumed  the 
attitude  of  a  quadruped,  it  would  trail  upon  the  ground,  and  fall  over  the  face. 

The  hair  also  presents  peculiarities,  or  differences,  in  many  respects ;  for  example,  in 
direction,  some  hair  being  long  and  smooth,  some  crisped  and  woolly  ;  this  latter  kind  is 
peculiar  to  the  negro  race,  and  it  never  grows  to  a  very  great  length  :  also  in  diameter, 
some  hair  being  excessively  fine,  and  some  large  and  coarse. t  It  differs,  again,  as  to 
quantity,  for,  in  general,  the  hair  of  the  head  is  more  abundant  in  the  female  than  in  the 
male,  as  if  the  activity  of  the  pilous  system  was  principally  confined  to  the  hairy  scalp 
in  the  former  sex ;  and,  lastly,  in  its  colour,  from  which  certain  very  important  distinc- 
tions among  men  are  established. 

Every  different  shade  in  the  colour  of  the  hair  may  be  referred  to  three  principal  va- 
rieties, the  black,  the  flaxen,  and  the  red.  The  flaxen  hair  belongs  particularly  to  the 
inhabitants  of  the  north,  and  to  persons  of  lymphatic  and  sanguineous  temperaments ; 
the  black  is  characteristic  of  the  inhabitants  of  the  south,  and  of  those  of  a  bilious  and 
sanguineous  temperament ;  the  red  belongs  to  no  particular  temperament ;  and  in  our 
ideas  of  beauty,  this  coloured  hair,  which  is  usually  accompanied  with  a  disagreeable 
odour  of  the  perspiration,  is  regarded  as  a  natural  misfortune. 

The  beard  and  whiskers  are  peculiar  to  the  male  sex ;  they  occupy  the  lower  part  of 
the  face,  and,  consequently,  leave  uncovered  all  those  parts  which  are  principally  con- 
cerned in  giving  expression  to  the  physiognomy,  viz.,  the  ocular,  nasal,  and  frontal  re- 
gions. We  cannot  insist  too  strongly  on  the  connexion  existing  between  the  develop- 
ment of  the  genital  organs  and  that  of  the  beard.  The  eunuch  is  almost  destitute  of 
that  appendage. 

The  great  attention  rendered  necessary  by  wearing  a  long  beard  and  long  hair  has  led 
to  the  custom  of  cutting  the  hair  and  shaving.  It  is  remarkable  that  the  most  effemi- 
nate nations,  the  Orientals,  for  example,  are  those  among  whom  long  beards  are  in  high- 
est estimation.  The  influence  of  these  different  customs  upon  the  health  are  deservedly 
subjects  of  examination  for  those  who  study  Hygiene. 

Structure  and  Growth  of  Hairs. — The  only  method  of  obtaining  an  accurate  knowledge 
of  the  structure  of  hairs  is  to  study  their  growth.  The  extremity  of  the  hair  which  is 
inserted  into  the  skin  is  contained  in  a  sort  of  follicle,  very  analogous  to  the  dental  folli- 

*  The  spines  of  the  hedgehog,  the  bristles  of  the  boar,  the  hair  of  horses,  the  wool  of  sheep,  and  the  fur  of 
most  mammalia,  are  different  kinds  of  hair. 

t  [The  hair  of  the  head  also  varies  in  its  form;  a  section  being  a  more  or  less  flattened  oval,  or  even  reni 
form,  from  the  hair  being  excavated  along  one  side.    On  the  face,  the  hairs  are  still  more  flattened.] 


THE    ORGAN    OF   TASTE.  639 

'.les.  Tliis  hair-follicle  (e,fig.  230),  which  is  the  formative  organ  of 
-lie  hair,  is  imbedded  in  the  sub-cutaneous  cellular  tissue  (g),  and  is 
prolonged  to  the  surface  of  the  skin  by  a  sort  of  meinbranous  canal, 
which  was  well  described  by  Bichat.  The  hair-follicles  consist  es- 
sentially of  a  pouch  or  sac,  and  a  papilla. 

The  membranous  pouch  or  sac  (c  c),  called  the  bursal  membrane 
by  Heusinger,  forms  a  sort  of  cul-de-sac,  having  a  narrow  neck,  and 
opening  externally  by  a  contracted  orifice,  through  which  the  hair 
(A)  passes  without  adhering  to  it  at  all.  Its  walls  are  sufficiently 
transparent  to  allow  the  hair  contained  in  its  cavity  to  be  seen.  If 
this  cavity  or  sac,  which,  according  to  M.  Dutrochet,  is  formed 
merely  by  the  inversion  of  a  portion  of  the  skin,  be  laid  open,  its  in- 
ternal surface  (c)  is  found  to  be  smooth,  not  adherent  to  the  hair,  but 
separated  from  it  by  a  reddish  liquid,  first  pointed  out  by  Heusinger.  Magnmrf." 

From  the  bottom  of  this  sac,  i.  e.,  from  the  part  farthest  from  the  orifice  through  which 
the  hair  protrudes,  a  papilla  (a),  called  the  pulp  of  the  hair,  arises :  this  papilla  is  of  a 
conical  form,  its  base  being  adherent,  while  its  apex  is  free ;  it  reaches  nearly  to  the 
orifice  of  the  sac,  and  even  projects  beyond  it  in  the  disease  called  plica  polonica. 
Bloodvessels  and  nerves  pass  to  the  bottom  of  the  hair-follicle,  and  are  probably  distrib- 
uted upon  the  papilla. 

It  is  upon  the  papilla  that  the  hair  is  formed.  At  its  commencement  it  resembles  a 
conical  horny  sheath,  which  is  exactly  moulded  upon  the  apex  of  the  papilla.  On  the  in- 
ner side  of  this  horny  cone  another  is  formed,  which  raises  up  the  preceding  one,  and 
so  on  in  succession,  the  entire  hair  constantly  maintaining  a  conical  form.  According 
to  the  experiments  of  Heusinger,  who  plucked  out  at  intervals  the  hairs  from  the  whis- 
kers of  a  dog,  and  afterward  killed  the  animal,  so  as  to  observe  the  successive  changes 
which  took  place  in  the  hair-follicles  during  the  development  of  the  new  hairs,  a  rather 
long  period  elapses  before  the  hair  projects  beyond  the  epidermis ;  but,  when  once  it  has 
overcome  that  obstruction,  its  growth  proceeds  rapidly. 

What  is  the  arrangement  of  the  epidermis  at  the  point  where  the  hair  emerges  beyond 
its  surface  1  According  to  some,  it  is  prolonged  upon  the  hair,  and  forms  its  outer  coat ; 
according  to  others,  it  dips  into  the  cavity  of  the  hair-follicle,  and  is  reflected  upon  the 
base  of  the  hair,  so  as  to  form  upon  it  an  epidermic  tube,  which  falls  off  in  scales  as  the 
hair  is  prolonged  outward ;  according  to  others,  again,  the  epidermis  has  no  connexion 
with  the  hair ;  and  I  am  the  more  inclined  to  subscribe  to  such  an  opinion,  because  the 
hair  is  of  the  same  size  both  before  and  after  it  has  left  the  follicle.* 

The  hair  is  the  product  of  a  secretion,  and,  therefore,  destitute  of  vitality,  being  form- 
ed by  a  series  of  small  horny  cones  fitted  one  into  the  other.  It  is  generally  admitted 
that  it  is  composed  of  a  homy,  colourless,  transparent,  epidermoid  sheath,  containing  a 
sort  of  coloured  pith  in  its  interior.  Bichat  presumed  that  this  central  substance  was 
formed  of  certain  bloodvessels  which  contained  the  colouring  matter ;  but  the  mode  in 
wiiich  the  hair  is  developed  proves  that  it  is  not  tubular,  and  also  that  the  colouring 
matter  itself  is  produced  by  the  papilla  at  the  same  time  as  the  epidermoid  sheath.  The 
white  hairs  of  old  people  are  merely  deprived  of  colouring  matter.  + 

The  Organ  of  Taste. 

The  structure  of  the  tongue,  the  organ  of  taste,  which  has  already  been  described  (see 
j).  332),  presents  a  greater  analogy  to  that  of  the  skin  than  any  other  of  the  organs  of 
liio  senses. 

Tlie  sense  of  taste  resides  essentially  in  the  papillary  membrane  which  covers  the  up- 
i>or  surface  of  the  tongue. t  It  has  already  been  stated  that  the  perforated  eminences 
found  at  the  base  of  the  tongue  are  not  papillae,  but  glands  ;  and  the  true  papillae  have 
been  divided  into  the  large  or  cahciform  papillae,  which  are  arranged  in  the  shape  of  the 
lettov  V  at  the  base  of  the  tongue,  and  the  small  papillae  ;  which  may  be  again  subdivided 
iiiro  the  conical,  the  filiform,  and  the  lenticular  or  fungiform,  according  to  their  respect- 
iv  shapes. 

i>ery  special  sense,  by  which  term  is  understood  ail  such  as  receive  sensations  dif- 
ftrent  from  that  of  touch,  properly  so  called,  presents  for  our  consideration  a  special  ap- 

*■  rThe  root  of  some  hairs  is  larger  than  the  shaft,  and  is  named  the  bulb  ;  this,  however,  does  not  depend 
(.u  thu  hair  being  covered  by  the  epidermis,  a  thin  layer  of  which  (d  d,fig.  230)  lines  the  follicles,  and  is  be- 
liiivdd  to  terminate  at  the  root  of  the  hair.  Into  each  hair-foUicle  one  or  more  sebaceous  glands  (i  i,fig'  227) 
;i.n;r  tlieir  secretion.] 

t  Lllairs,  like  the  nails,  consist,  according  to  recent  researches,  of  nucleated  corpuscles,  which  differ  in 
U.xm,  density,  and  arrangement,  in  different  parts  of  the  hair.  At  the  root,  upon  the  surface  of  the  papilla, 
»h:  re  they  are  first  developed,  they  are  soft  and  vesicular  ;  in  the  central  medullary  part  of  the  shaft  they  are 
b:inkr,  compressed,  and  polyhedral ;  in  the  cortical  part  they  form  an  immense  number  of  very  long  and  fine 
liiirrs,  and,  on  the  outside  of  these,  a  layer  of  short,  hard  scales. 

The  hairs  consist  principally  of  keratin  and  an  oily  matter  ;  besides  which,  they  yield  sulphur,  phosphorus, 
iron,  salts  of  lime,  and  traces  of  manganese,  silica,  and  magnesia.] 

X  [The  mucous  membrane  on  the  under  surface  of  the  tongue,  and  that  covering  the  buccal  surface  of  the 
soft  palate  and  the  immediately  adjacent  parts  of  the  fauces,  also  possess  the  sense  of  taste.] 


649  NEUROLOGY. 

paratus,  on  which  the  impressions  act,  and  a  special  nerve  or  nerves,  adapted  to  receive 
those  impressions  and  transmit  them  to  the  brain. 

The  nmscular  structure  of  the  tongue,  which  at  first  sight  appears  to  be  useful  only  in 
mastication,  deglutition,  and  the  articulation  of  sounds,  is  intimately  connected  with  the 
sense  of  taste,  which  would  have  been  exceedingly  imperfect,  had  not  the  gustatory 
membrane  been  capable  of  being  moved  over  the  bodies  to  be  tasted.  The  gustatory 
apparatus  of  the  tongue  consists,  then,  of  a  papillary  membrane  stretched  over  a  muscu- 
lar surface,  and  united  so  closely  to  it  that  it  is  impossible  to  separate  one  from  the  oth- 
er. Moreover,  this  membrane  is  constantly  kept  in  a  state  of  humidity,  and  occupies 
the  first  cavity  presented  by  the  digestive  apparatus. 

The  Gustatory  Papillary  Membrane. — All  the  elements  of  the  skin  are  found  in  the  gus- 
tatory membrane. 

The  chorion  is  as  dense  as  the  densest  part  of  the  chorion  of  the  skin  :  a  very  great 
number  of  muscular  fibres  are  inserted  into  it,  so  that  the  gustatory  membrane  can  be 
moved  not  only  as  a  whole,  but  each  part  of  it  has  its  own  separate  movements. 

The  papilla,  by  which  the  surface  of  the  tongue  is  rendered  so  rough,  may  be  said  to 
represent  the  papillary  body  of  the  skin  in  a  very  highly-developed  state.* 

The  lingual  papilla  are  supplied  with  nerves,  which  can  be  more  easily  shown  than 
those  in  the  cutaneous  papillee.  Haller  has  traced  them  into  the  papilla; ;  and  I  have  suc- 
ceeded in  doing  the  same,  but  without  being  able  to  ascertain  their  mode  of  termination. 

The  papillae  also  receive  bloodvessels,  which  are  so  abundant  that,  in  successful  injec- 
tions, the  papillary  body  appears  to  be  altogether  vascular. 

The  Lymphatic  Network. — By  making  a  superficial  puncture  into  any  part  of  the  mem- 
brane which  covers  the  dorsum  or  the  borders  of  the  tongue,  we  may  inject  a  lymphatic 
network  upon  it,  precisely  similar  to  that  found  in  the  skin. 

The  mucous  body,  or  rete  mucosum,  does  not  exist  as  a  distinct  membrane  upon  the 
tongue  any  more  than  in  the  skin.  I  have  already  stated  that  it  was  while  examining 
the  boiled  tongue  of  the  ox  that  Malpighi  discovered  a  glutinous  stratum  situated  be- 
tween the  epidermis  and  the  papillae,  and  perforated  by  a  number  of  openings,  corre- 
sponding to  that  of  the  papillae  themselves ;  hence  the  name  of  reticulum  which  he  gave 
it  ;t  but  it  is  as  impossible  to  demonstrate  it  upon  the  tongue  as  in  the  skin. 

The  Pigmentum. — There  is  never  any  black  colouring  matter  in  the  tongue  of  the  hu- 
man subject ;  but  it  is  distinct  upon  the  tongue  of  some  animals,  as  the  ox,  and  can  be 
easily  demonstrated  between  the  papillae  and  the  epithelium.t 

The  Epithelium. — Each  papilla  is  covered  with  a  sort  of  epidermic  sheath,  which,  ac- 
cording to  Haller,  was  discovered  by  Mery  and  Cowper,  and  which  has  been  perfectly 
described  by  Albinus  under  the  name  of  the  periglottis.  This  epidermis,  or  epithelium, 
so  easy  of  demonstration  in  the  lower  animals,  in  which  it  has  the  consistence  of  horn, 
may  be  also  readily  shown  in  the  human  subject,  although,  in  accordance  with  the  great- 
er perfection  of  the  sense  of  taste  in  man,  the  epithelium  is  comparatively  thin.  If  the 
upper  surface  of  the  tongue  be  examined  with  a  lens,  especially  after  maceration,  the 
lingual  epithelium  will  be  seen  to  be  arranged  in  precisely  the  same  manner  as  the  epi- 
dermis of  the  skin,  and  to  form  a  protecting  sheath  for  each  papilla.  In  persons  who 
have  sunk  after  long  abstinence,  the  epithelial  covering  forms  several  imbricated  layers, 
which  can  be  rubbed  off;  the  fur  which  adheres  to  the  tongue  is  in  a  great  measure 
formed  by  this  debris  of  the  epithelium  somewhat  dried.  The  epithelium  of  the  tongue 
can  be  removed  by  friction ;  and,  in  certain  inflammatory  diseases,  the  tongue  is  denuded 
of  it.    When  one  of  the  lingual  papillae  is  thus  exposed,  it  becomes  excessively  painful. 

The  Nerves  of  the  Tongue. — No  other  organ,  perhaps,  of  equal  size,  receives  so  many 
nerves  as  the  tongue  :  one  pair,  the  ninth  or  hypoglossal,  is  exclusively  appropriated  to 
it ;  and  it  also  receives,  on  each  side,  the  glosso-pharyngeal  branch  of  the  eighth,  and 
the  lingual  branch  of  the  fifth  of  the  cerebral  nerves.  Which  of  these  nerves  must  be 
regarded  as  the  nerve  of  taste  in  the  tongue  1  Evidently  the  one  that  is  distributed  to 
the  papillae.  On  this  account,  since  the  time  of  Galen,  the  lingual  branch  of  the  fifth 
pair,  or  the  lingual  nerve,  as  it  is  called,  has  been  regarded  as  the  gustatory  nerve ; 
though  it  would  seem  more  natural  to  admit,  with  Boerhaave,  that  the  hypoglossal  nerve, 
which  is  distributed  exclusively  to  the  tongue,  should,  as  it  were,  preside  over  the  spe- 
cial sense  situated  in  this  organ.  But  the  lingual  nerve  is  found  to  enter  the  tongue  at 
its  corresponding  border,  and  to  spread  out  into  branches  which  pass  vertically  upward, 
and  are  exclusively  distributed  to  the  papillary  membrane  of  the  anterior,  or  free  portion 
of  the  tongue. 

The  ninth  or  hypoglossal  nerve  of  each  side  runs  from  behind  forward,  between  the  ge- 
nio-glossus  and  stylo-glossus  muscles,  and  communicates  with  the  lingual  nerve,  so  as 
to  form  the  lingual  plexus.    It  is  not  certain  that  some  of  the  filaments  of  the  hypoglos- 

*  If  the  epidennic  tubes,  which  are  so  remarkably  distinct  on  the  foot  of  the  bear,  be  removed  from  the  pa- 
pillae, the  latter,  when  exposed,  exactly  resemble  those  of  the  tongue.] 

t  "  Hanc  fabricam  a  Malpighio  inventam,  et  a  Bellino  libenter  acceptam,  scriptores  anatomicorum,  et  phys- 
iologicorum  operum  iconibus  etiam  pictis  expresserunt." — {Haller,  t.  v.,  lib.  xiii.,  p.  107.) 

t  [The  pigment  in  these  cases,  and  the  lingual  rete  mucosum  also,  are  the  lowermost  layers  of  the  ectra 
vascular  squamous  epithelium.] 


THE   NOSE»  641 

sal  nerve  do  not  reach  the  papillae ;  but  there  is  no  doubt  but  that  almost  all  of  them  are 

lost  in  the  intrinsic  muscles  of  the  tongue. 

The  right  and  left  glosso-pharyngeal  nerves  supply  the  base  of  the  tongue,  and  are  ex- 
clusively distributed  to  the  mucous  membrane  covering  that  part.  No  filament  of  the 
glosso-pharyngeal  nerve  is  intended  for  the  muscular  fibres  ;  and  it  is  a  remarkable  fact, 
that  in  one  case  in  which  the  facial  nerve  sent  a  branch  to  the  tongue  supplementary  to 
the  glosso-pharyngejd,  that  branch  was  distributed  precisely  in  the  same  manner  as  the 
glosso-pharyngeal  itself;  that  is,  it  was  exclusively  distributed  to  the  mucous  membrane 
at  the  base  of  the  tongue.  From  what  is  stated  above,  then,  it  is  anatomically  shown 
that  the  lingual  branch  of  the  fifth  nerve  and  the  glosso-pharyngeal  nerve  are  the  specijil 
nerves  of  the  tongue.* 

The  following  case  is  no  less  demonstrative  of  the  same  fact ;  Anf  individual  had  com- 
plete paralysis  of  the  right  half  of  the  tongue.  That  side  of  the  tongue  became  atrophied, 
and  had  scarcely  one  third  of  its  natural  thickness.  Both  its  tactile  and  gustative  sen- 
sibiUty  were  equally  acute  on  the  two  sides  of  the  organ.  After  the  death  of  the  person 
thus  afflicted,  an  acephalo-cyst  was  found  in  the  right  posterior  condyloid  foramen,  which 
had  caused  a  complete  atrophy  of  the  right  hypoglossal  nerve.  The  corresponding  half 
of  the  tongue  had  undergone  the  fatty  degeneration. 

The  Organ  of  Smell. 

The  organ  of  smell  is  situated  in  a  cavity  formed  within  the  bones  of  the  face,  as,  in- 
deed, are  most  of  the  other  senses ;  it  is  placed  at  the  entrance  of  the  respiratory  pas- 
sages, and  above  the  organ  of  taste,  with  which  it  has  many  points  of  relation.  Although 
situated  in  the  median  line,  it  is  a  double  organ.  It  consists  of  an  external  apparatus, 
which  serves  to  protect  the  organ,  to  keep  it  in  the  necessary  state  of  moisture  for  the 
proper  exercise  of  its  functions,  and  to  direct  the  air  towards  that  part  of  it  which  is  en- 
dowed with  the  greatest  olfactory  sensibility  :  this  is  the  nose,  properly  so  called. 

And,  secondly,  of  two  complicated  and  winding  cavities,  the  nasal  fossa,  lined  by  a 
mucous  membrane,  cedled  the  pituitary  membrane,  which  is  the  essential  seat  of  the  sense 
of  smell. 

The  J^ose. 

The  nose  resembles  in  form  a  three-sided  pyramid,  directed  vertically,  and  projecting 
from  the  middle  of  the  face,  so  that  the  olfactory  organ  is  the  most  anterior  of  all  the  or- 
gans of  the  special  senses. 

Its  numerous  varieties  in  shape  and  size  fall  under  the  consideration  of  painters  rather 
than  anatomists  ;  for  these  varieties  have  greater  effect  upon  the  physiognomy  than  upon 
the  exercise  of  its  functions. 

On  each  side  of  the  nose,  at  its  lower  part,  is  observed  a  semicircular  furrow,  having 
its  concavity  directed  downward,  and  forming  the  upper  border  of  the  alse  nasi ;  from 
this  furrow,  on  either  side,  the  naso-labial  furrow  of  the  semeiologists  commences.  The 
lateral  surfaces  of  the  nose  form,  by  their  union,  the  dorsum,  which  is  either  straight, 
convex,  or  concave,  according  to  the  subject ;  differences  which,  in  a  great  measure, 
determine  the  national  or  individual  forms  of  this  part  of  the  face.  The  term  lobe  of  the 
nose  is  applied  to  the  rounded  eminence  in  which  the  dorsum  nasi  terminates  below. 

The  summit,  or  root  of  the  nose,  is  separated  from  the  nasal  protuberance  by  a  trans- 
verse furrow.  The  base  of  the  nose  presents  two  elliptical  or  semilunar  orifices,  called 
the  nostrils  (jiares) :  the  long  diameters  of  these  two  orifices  are  directed  horizontally 
backward  and  outward,  and  they  are  separated  from  each  other  by  an  antero-posterior 
septum  ;  they  are  provided  with  stiff"  hairs,  or  vibrissce,  which  serve  to  arrest  any  small 
particles  floating  in  the  air.t 

The  direction  of  the  nostrils  is  a  proof  that  the  erect  position  is  natural  to  man ;  for, 
if  he  were  to  assume  the  attitude  of  a  quadruped,  only  the  dorsum  of  the  nose  would  be 
directed  towards  odoriferous  bodies.  The  situation  of  the  nostrils  above  the  orifice  of 
the  mouth  explains  how  no  ^llimentary  substance  can  be  introduced  into  that  cavity 
without  having  been  previously  examined  by  the  sense  of  smell. 

The  nose  consists  of  a  skeleton  or  basis,  and  of  certain  muscles ;  it  is  covered  by  the 
skin  externally,  and  by  a  mucous  membrane  internally ;  and  it  receives  both  vessels  and 
nerves. 

The  Structure  of  the  Nose. 
The  basis  or  framework  of  the  nose  is  composed  of  bone,  cartilage,  and  fibrous  tissue. 

*  [The  result  of  the  vast  number  of  experiments  and  observations  made  upon  this  subject,  by  persons  of  op- 
posite opinions,  would  appear  to  be,  that  the  lingual  nerve  (a  branch  of  the  fifth),  and  the  lingual  portion  of 
the  glosso-pharyngeal  nerves,  are  both  of  them  gustatory  nerves,  and  also  nerves  of  ordinary  sensibility  to  the 
tongue.  The  portion  of  the  palate  and  fauces  endowed  with  the  sense  of  taste  derives  its  power  from  the  pal- 
atine nerves,  which  are  given  off  from  a  gangUon  (Meckel's)  connected  with  the  second  division  of  the  fifth 
nerve.] 

t  This  use  of  the  vibrissse  becomes  very  evident  in  serious  diseases  ;  when,  in  consequence  of  the  humed 
respiration,  dry  particles  floating  in  the  air  become  attached  like  a  fine  powder  to  these  hairs.  The  coUectioo 
of  particles  of  dust  around  the  nostrils  often  warns  the  practitioner  of  the  serious  nature  of  a  disease 

4M 


642  NEUROLOGY. 

The  osseous  portion  occupies  the  upper  part  of  the  organ,  and  consists  of  the  proper 
nasal  bones,  and  of  the  ciscending  processes  of  the  superior  maxillary  bones. 

The  cartilaginous  part  consists  of  the  two  lateral  cartilages  of  the  nose,  to  which  we  may 
add  the  cartilage  of  the  septum,  although  it  rather  forms  part  of  the  nasal  fossae  than  of 
the  nose  properly  so  called ;  and,  secondly,  of  the  two  alar  cartilages,  or  cartilages  of  the 
nostrils,  making  five  in  all.  To  this  we  must  add  certain  cartilaginous  nod^iles,  situated 
between  the  lower  part  of  the  cartilages  of  the  alae  and  that  of  the  septum.  Santorini 
described  eleven  cartilages  in  the  nose,  doubtless  because  he  reckoned  certain  cartila- 
ginous nodules,  which  are  sometimes  accidentally  developed  in  the  substance  of  the 
fibrous  tissue.* 

The  fibrous  portion  of  the  nose  consists  of  a  fibrous  layer,  which  occupies  the  interval 
between  the  lateral 'cartilages  of  the  nose  and  the  cartilages  of  the  alae. 

From  this  structure,  it  follows  that  the  nose  is  inflexible  above,  flexible  in  the  middle, 
and  extremely  movable  below.     This  arrangement  has  the  threefold  advantage  of  pro- 
viding against  fractures  of  the  most  prominent  part  of  the  nose,  of  permitting  the  dilata- 
tion of  the  nostrils,  and,  lastly,  in  consequence  of  the  solidity  of  the  highest  and  narrow- 
est part  of  the  n2isal  fossae,  of  ensuring  a  free  passage  to  the  air. 
The  lateral  cartilages  of  the  nose  (a  a,  fig.  231)  are  of  a  triangular  form ;  and  they  are 
Fig.  231.        united  together  along  their  anterior  margins,  which  are  thick  above,  so 
as  to  form  a  sharp  ridge,  which  constitutes  the  dorsum  of  the  nose. 
Along  the  line  of  union  there  is  a  sort  of  furrow  or  groove,  which  can 
be  felt  even  through  the  skin.     By  their  upper  and  posterior  margins, 
they  are  articulated  with  the  nasal  bones ;  I  say  articulated,  because 
there  is  no  continuity  of  substance,  but  the  parts  are  connected  by 
fibrous  tissue,  which  allows  a  considerable  degree  of  motion.     Their 
lower  margins  are  convex,  and  correspond  in  front  to  the  cartilages  of 
the  alae  of  the  nose,  and  behind  to  the  fibrous  tissue  which  occupies  the 
intervals  between  the  cartilages.     The  lateral  cartilages  are  intimately 
united  with  the  cartilage  of  the  septum,  along  the  dorsum  of  the  nose  ; 
so  that  we  might  regard  these  three  pieces  as  forming  a  single  cartilage. 
The  thickest  part  of  each  lateral  cartilage  is  above  and  in  front. 
The  cartilages  of  the  nostrils  are  generally  called,  after  Bichat,  the  filro-cartilages  of 
the  alcR  of  the  nose ;  but  we  have  already  seen  that  some  of  the  fibro-cartilages  of  Bichat 
are  thin  layers  of  ordinary  cartilage,  while  others  consist  merely  of  condensed  fibrous 
tissue.     The  so-called  fibro-cartilages  of  the  nostrils  belong  to  the  former  kind.     There 
is  but  a  single  cartilage  on  each  side  {b  b,fig.  231)  for  the  ala  nasi,  the  lobe,  and  the  in- 
ferior portion  of  the  septum ;  it  consists  of  an  irregular  lamina  folded  upon  itself  into  a 
semi-ellipse  or  parabola,  opening  behind.    We  shall  examine  its  external  and  internal 
portions. 

The  external  portion  (b)  is  extremely  thin,  and  corresponds  to  the  ala  of  the  nose ;  it  is 
not  situated  in  the  substance  of  the  ala,  but  is  placed  above  it,  so  that  its  lower  margin 
corresponds  to  the  curved  furrow  which  forms  the  upper  boundary  of  the  ala.t 

The  internal  portion  (b,fig.  232)  is  thicker  than  the  external,  and  is  situated  upon  a 
lower  plane  than  it :  it  corresponds,  on  the  inside,  to  the  internal  portion  of  the  cartilage 
of  the  opposite  side,  from  which  it  is  separated  above  by  the  cartilage  of  the  septum. 
The  internal  portions  of  the  two  alar  cartilages  are  separated  from  each  other  by  some 
rather  loose  cellular  tissue,  which  allows  them  to  move  upon  each  other,  and  also  per- 
mits the  cartilage  of  the  septum  to  extend  between  them,  without  interfering  with  them 
at  all.  The  internal  portions  of  the  cartilages  of  the  alae  do  not  reach  the  anterior  nasal 
spine,  but  terminate  abruptly  at  a  certain  distance  from  it,  by  forming  a  projection,  which 
is  very  distinct,  especially  in  some  individuals,  and  which  sensibly  elevates  the  mucous 
membrane  at  the  entrance  of  the  nostrils.  At  the  point  of  union  between  the  internal 
and  external  portions  of  each  alar  cartilage,  that  is  to  say,  at  the  summit  of  the  parabola, 
the  cartilage  itself  becomes  wider  and  excavated  behind,  and  assists  in  forming  the  lobe 
of  the  nose.  The  margins  of  these  cartilages  are  irregularly  notched  or  scolloped.  The 
upper  margins  are  united  to  the  other  cartilages  by  means  of  a  fibrous  tissue,  which  al- 
lows them  to  move  frgely,  both  upon  the  cartilage  of  the  septum  and  upon  the  lateral 
cartilages  of  the  nose. 

A  small  cartilaginous  nodule  is  found  on  either  side,  between  the  lobe  of  the  nose  and 
the  cartilage  of  the  septum ;  the  only  use  of  these  nodules  is  to  facilitate  the  movements 
of  the  lobe  upon  the  septum. 

The  cartilage  of  the  septum  nasi  (c,fig.  232)  occupies  the  triangular  interval  between 

the  perpendicular  plate  of  the  ethmoid  bone  and  the  vomer.     It  consists  of  two  parts  : 

one,  wide  and  free,  which  is  that  generally  described ;  the  other,  which  is  narrow,  and 

may  be  called  the  caudal  prolongation  of  the  cartilage,  is  received  into  the  bony  portion 

•  of  the  septum,  between  the  two  lamellae  of  the  vomer 

*  See  note,  infra. 

t  [Two  or  three  cartilaginous  nodules  (e  e,fig.  231)  are  generally  found  appended  in  a  curved  line  to  the 
posterior  extremity  of  this  portion  of  the  cartilage  of  the  ala.l 


THE   PITUITARY    MEMBRANE.  643 

The  fret  portion  of  the  cartilage  is  thick  and  triangular ;  it  has 
the  same  direction  as  the  bony  septum,  and  presents  two  lateral 
surfaces,  covered  by  the  pituitary  membrane  ;  an  anterior  margin, 
of  which  the  upper  half  (c,  fg.  231)  is  blended  with  the  lateral 
cartilages  along  the  dorsum  of  the  nose,  while  its  lower  half  is 
free,  convex,  directed  downward,  and  received  between  the  two 
cartilages  of  the  nostrils  ;  a  superior  and  posterir  margin,  which  is 
extremely  thick  and  rough,  and  is  intimately  united  to  the  corre- 
sponding margin  of  the  perpendicular  plate  of  the  ethmoid  bone 
(e,  Jig.  232) :  the  mode  in  which  this  union  is  effected  is  not  by 
articulation,  but  by  a  continuity  of  tissue,  like  that  between  the 
costal  cartilages  and  the  ribs  ;  lastly,  an  inferior  margin,  which  is 
received  between  the  two  plates  of  the  vomer  (»).  The  groove 
into  which  it  is  received  is  very  deep  ;  and  as  the  two  plates  of 
the  vomer  become  more  and  more  separated  in  extending  forward,  so  does  the  corre- 
sponding margin  of  the  cartileige  increase  in  thickness  ;  hence  the  lower  extremity  of 
the  septum  frequently  projects  considerably  into  one  or  other  of  the  nostrils. 

The  caudal  prolongation  of  the  cartilage  of  the  septum  may  be  seen  by  carefully  exani 
ining  the  retreating  angle  formed  by  the  perpendicular  plate  of  the  ethmoid  and  the  vo- 
mer ;  in  which  situation  the  cartilage  of  the  septum  gives  off  a  considerable  prolonga- 
tion, in  the  form  of  a  band,  which  occupies  the  interval  between  the  two  plates  of  the 
vomer,  and  is  attached  to  the  rostrum  of  the  sphenoid  bone.  This  cartilaginous  band  is 
contained  entirely  within  the  substance  of  the  middle  portion  of  the  bony  septum  :  its 
upper  margin  is  thin,  and,  as  it  were,  toothed ;  the  lower  margin  is  thick  and  rounded. 
The  two  naso-palatine  nerves  are  situated  in  the  same  canal  as  the  cartilage,  and  are 
placed  one  on  each  side  of  it. 

The  muscles  of  the  nose  are  the  pyTamid2ilis  nasi,  the  levator  labii  superioris  alaeque 
nasi,  and  the  transversalis  nasi,  or  compressor  narium,  which  we  have  described  as  a 
dependance  of  the  depressor  alae  nasi,  or  rayrtiformis  :  an  accurate  description  of  these 
muscles  is  still  to  be  desired. 

The  skin  covering  the  nasal  bones  and  the  lateral  cartilages  of  the  nose  has  no  par- 
ticular character :  it  is  thin  and  movable.  That  which  covers  the  alae  and  the  lobe  of 
the  nose  is  very  thick  and  extremely  dense  ;  it  crepitates  under  the  knife,  to  such  a  de- 
gree, that  cartilages  have  been  supposed  to  exist  in  the  substance  of  the  alae.  We  have 
seen,  however,  that  the  cartilages  of  the  nostrils  are  not  prolonged  into  the  alae,  which 
are  composed  essentially  of  the  dense  integument  just  described,  and  which  is  reflected 
inward  upon  itself  around  the  margins  of  the  nostrils. 

I  should  remark,  that  the  antero-posterior  diameter  of  the  opening  of  each  nostril  is 
much  less  than  that  of  the  corresponding  cartilage  ;  this  depends  upon  the  fact  that  the 
skin  is  prolonged  anteriorly,  and  is  reflected  for  some  lines  below  and  behind  the  lower 
margin  of  the  cartilage. 

The  skin  of  the  nose  is  remarkable  for  the  great  development  of  its  sebaceous  follicles. 
The  orifices  of  these  follicles  are  shown  in  many  individuals  by  certain  black  points, 
which  are  nothing  more  than  the  sebaceous  matter  discoloured.  When  forced  out  of 
the  follicles  by  lateral  pressure,  the  masses  of  sebaceous  matter  resemble  in  form  small 
worms. 

The  skin,  which  is  reflected  upon  itself  around  the  margins  of  the  nostrils,  preserves 
the  character  of  integument  as  far  as  where  it  is  provided  with  hairs,  and  then  suddenly 
assumes  the  characters  of  mucous  membranes. 

The  Pituitary  Membrane. 

The  pituitary  or  Schneiderian*  membrane,  the  immediate  seat  of  smell,  is  a  fibro-mucous 
membrane,  which  lines  the  whole  extent  of  the  nasal  fossae,  and  is  prolonged,  with  some 
modifications  of  texture,  into  the  different  cells  and  sinuses  which  open  into  those  fossae. 

When  covered  with  this  membrane,  the  nasal  fossae  present  a  configuration  differing 
in  many  respects  from  that  which  they  have  in  the  skeleton.  Many  of  the  foramina  and 
canals  are  closed,  and  several  are  contracted  in  their  dimensions.  The  irregularities 
of  the  surface  of  the  turbinated  bones  are,  in  some  measure,  concealed.  Besides  this, 
the  mucous  membrane,  where  it  is  reflected  upon  itself,  forms  a  number  of  folds,  some 
of  which  prolong  the  turns  of  the  turbinated  bones  ;  while  others,  more  or  less,  contract 
the  orifices  of  communication  between  the  various  cells  and  sinuses  and  the  nasal  fossae. 

The  pituitary  membrane,  originating,  then,  on  the  one  hand,  from  the  skin,  which  is 
reflected  at  the  margins  of  the  nares,  and  provided  with  hairs  {h,Jig.  233),  is,  on  the  other 
hand,  continuous,  without  any  line  of  demarcation,  with  the  mucous  membranes  of  the 
pharynx  and  velum  palati  (at  t  s),  of  the  Eustachian  tubes  (at  m),  and  of  the  nasal  ducts 
(at  r).     In  the  roof  of  each  nasal  fossa  {u  v)  it  closes  the  foramina  of  the  cribriform  plate 

*  Conrad  Victor  Schneider  (de  Caiarrho)  gave  his  name  to  this  membrane,  because  he  was  the  first  to  refute 
•nccessfuUy  the  erroneous  notion  of  the  ancients,  that  the  secretion  of  the  nasal  fossae  descended  from  llie  ven 
tricles  of  the  brain  ;  the  common  term  cold  in  the  head  still  remains  as  a  vestig-e  of  this  error 


644 


NEUROLOGY. 


Fig.  233. 


of  the  ethmoid  bone,  and  those  of  the  nasal  bones,  so  that  all  the  vessels  and  nerves 
which  pass  through  these  foramina  enter  the  mucous  membrane  by  its  external  surface  ; 
before  it  enters  into  the  sphenoidal  sinus,  it  forms  a  fold  around  the  orifice  of  that  sinus, 
by  which  the  opening  is  narrowed,  so  as  to  have  the  form  of  a  vertical  fissure  (see  the 
bristle  marked  d). 
Upon  the  external  wall  of  each  nasal  fossa  (see  Jig.  233)*  it  covers  a  great  number  of 

parts,  counting  from  below  upward,  viz.,  the 
inferior  meatus,  at  the  upper  and  anterior  part 
of  which  it  meets  with  the  lower  orifice  of 
the  nasal  duct  {r,figs.  233,  234) ;  around  this 
opening  it  forms  a  semilunar  valvular  fold, 
the  free  margin  of  which  is  directed  down- 
ward, and  which  prolongs  the  canal  of  the 
ducts  to  a  greater  or  less  distance  in  differ- 
ent subjects  ;  in  passing  a  probe  into  the  na- 
sal duct  from  the  inferior  meatus,  this  valve 
must,  almost  of  necessity,  be  torn. 

From  the  inferior  meatus  the  pituitary 
ttiembrane  is  reflected  upon  the  inferior  tux' 
hinated  bone  (c  c,figs.  233,  234),  which  appears 
longer  in  the  recent  state,  in  consequence 
of  a  fold  of  the  mucous  membrane  being  con- 
tkiued  in  front,  and  another  still  more  marked  behind  the  bone  :  this  is  the  thickest  part 
of  the  nasal  mucous  membrane. 

In  the  middle  meatus  (t)  the  pituitary  membrane  covers  the  infundibulum,  at  tlie  lower 
extremity  of  which  is  an  ampulla  or  dilatation,  where  the  orifice  of  the  maxillary  sinus  is 
generally  found.  This  orifice  (see  bristle  a,  fig.  234)  has  a  very  different  appearance 
from  that  which  it  presents  in  the  dried  scull :  it  is  extremely  narrow,  scarcely  admit- 
ting the  blunt  end  of  a  common  probe.  It  sometimes  appears  as  if  it  were  wanting ; 
but  it  will  then  be  found  opposite  the  middle  of  the  infundibulum ;  in  this  case,  the  max- 
illary sinus  might  be  said  to  communicate  directly  with  the  frontal  sinus.  Not  unfre- 
quently  the  maxillary  sinus  opens  both  into  the  middle  meatus  and  the  infundibulum 
The  pituitary  membrane  is  prolonged  from  the  infundibulum  into  the  anterior  ethmoidal 
cells  (c  e,  fig.  234),  and  into  the  frontal  and  maxillary  (m  m)  sinuses.  If  we  remove  the 
middle  turbinated  bone,  we  find  a  considerable  projection,  which  bounds  the  infundibu- 
lum above  (n,  fig.  233),  and  corresponds  to  a  large  ethmoidal  cell.  Upon,  the  back  part 
of  this  projection,  on  which  the  middle  turbinated  bone  is  moulded,  an  opening  (see  bris- 
tle) is  often  found  leading  into  this  great  cell,  and  on  its  fore  part  (at  e),  one  or  more  or- 
ifices leading  into  the  anterior  and  superior  ethmoidal  cells. 

From  the  middle  turbinated  bone  {b,  figs.  233,  234),  which  is  continued  backward  hy 

a  fold  of  the  membrane,  the  pituitary  membrane 
passes  into  the  superior  meatus,  where  I  have  fre- 
quently met  with  four  or  five  openings  leading  into 
as  many  of  the  posterior  ethmoidal  cells,  which,  in 
this  case,  did  not  communicate  with  each  other :  I 
have  even  seen  the  orifice  of  an  ethmoidal  cell  upon 
the  superior  turbinated  bone  (a). 

The  pituitary  membrane  dips  into  all  the  etlimoid- 
al  cells,  and  into  the  frontal  sinuses,  either  directly 
or  indirectly,  but  it  does  not  enter  the  spheno-pala- 
tine  foramen,  which,  on  the  contrary,  is  completely 
closed  by  it. 

Upon  the  septum  the  pituitary  membrane  is  remark- 
able for  its  thickness,  being  exceeded  in  this  respect 
only  by  the  membrane  covering  the  inferior  turbinated  bone.  We  do  not  find  in  man 
that  prolongation  or  cul-de-sac,  which  is  so  very  distinct  in  some  animals,  in  front  of 
the  lower  border  of  the  septum ;  but  at  this  point  the  pituitary  membrane  closes  the 
two  superior  orifices  of  the  anterior  palatine  canal. 

Structure. — The  pituitary  membrane  is  a  mucous  membrane,  and  its  peculiarity  con- 
sists in  its  being  extended  over  osseous  and  cartilaginous  surfaces.  Its  free  surface  is 
smooth,  red,  and  scattered  over  with  foramina,  from  which  a  great  quantity  of  mucus 
maybe  expressed.  +  Its  adherent  surface  is  intimately  united  to  the  periosteum  and 
perichondrium  of  the  bones  and  cartilages  of  the  nasal  fossee,  so  that  it  is  classed  among 
the  fibro-mucous  membranes. 

*  [In  this  figure,  portions  of  the  middle  and  inferior  conchse  are  represented  as  cut  away,  to  show  the  parts 
m  the  middle  and  inferior  meatuses.] 

t  [In  the  nasal  fossa;  the  epithelium  of  the  pituitary  membrane  is  columnar  and  ciliated  ;  in  the  sinuses  it 
approaches  the  squamous  in  character,  but  yet  it  is  provided  with  cilia,  the  movements  of  which  have  been 
obserTed  in  the  lower  animals  to  produce  currents  towards  the  openings  of  the  respective  sinuses.] 


Fig.  234. 


THE    ORGANS    OF   SIGHT.  645 

The  pituitary  membrane  is  generally  thicker  than  the  other  mucous  membranes,  so 
that  it  is  very  easy  to  determine  the  highly  vascular  and  truly  erectile  structure  of  this 
membrane.  If  it  be  punctured,  and  the  tube  of  a  mercurial  injecting  apparatus  intro- 
duced, the  mercury  w^ill  immediately  enter  the  cells  of  the  erectile  tissue,  and  from 
thence  pass  into  the  veins  arising  from  those  cells.  If  a  more  superficial  puncture  be 
made,  a  lymphatic  network  will  be  injected,  situated  so  superficially,  that  the  mercury 
exhibits  all  its  metallic  lustre.  This  lymphatic  network  has  no  communication  with  the 
venous  cells  just  mentioned.* 

This  lymphatic  network,  which  is  common  to  all  the  mucous  membranes,  gives  to  the 
non-vascular  layer  by  which  they  are  covered  the  appearance  of  a  serous  membrane. 

The  pituitary  membrane  receives  a  great  number  of  arteries,  which  penetrate  it  by  sev- 
eral points,  and  which  are  almost  all  derived  from  the  same  source,  viz.,  the  internal 
maxillary  artery ;  as,  for  example,  the  spheno-palatine,  the  infra-orbital,  the  superior  al- 
veolar, the  palatine,  and  the  pterygo-palatine.  Some  arise  from  the  ophthalmic  arterj', 
viz.,  the  supra-orbital  and  the  ethmoidal ;  and  others  from  the  facial  artery,  viz.,  the  dor- 
salis  nasi,  the  artery  of  the  alae,  and  the  artery  of  the  septum. 

The  capillary  veins  are  so  numerous,  that  they  in  a  great  measure  form  the  basis  of 
the  pituitary  membrane  ;  the  larger  veins  which  proceed  from  them  follow  the  course  of 
the  arteries,  and  enter,  by  very  large  trunks,  into  the  internal  maxillary,  the  facial,  and 
the  ophthalmic  veins.  There  are  numerous  communications  between  these  last-named 
veins  and  those  of  the  ethmoidal  region  of  the  base  of  the  cranium. 

The  spongy  character  of  the  internal  surface  of  the  nasal  fossae,  and  more  particularly 
of  the  surface  of  the  turbinated  bones,  is  due  to  certain  grooves  and  foramina  intended 
for  the  reception  and  transmission  of  bloodvessels. 

I  am  only  acquainted  with  the  superficial  lymphatic  network  already  noticed.  In  order 
to  inject  it,  it  is  necessary  to  scratch  the  membrane  with  the  injecting  pipe. 

Are  there  any  glands  or  follicles  in  the  pituitary  membrane  1  Steno  has  described  cer- 
tain glands  which  I  have  not  been  able  to  find.  The  follicles  in  this  membrane  are  rather 
difficult  to  be  shown. 

Like  all  the  organs  of  the  special  senses,  the  pituitary  membrane  is  provided  vdth  a 
special  nerve,  called  the  olfactory,  the  nerves  of  the  two  sides  constituting  the  first  pair 
of  cerebral  nerves.  Comparative  anatomy  shows  that  the  development  of  the  olfactory 
nerves  is  in  relation  with  the  development  of  the  sense  of  smell,  and  thus  establishes,  in 
a  most  positive  manner,  the  generally-received  opinion  regarding  the  function  of  this  pair 
of  nerves.  Without  entering  here  into  the  description  of  the  olfactory  nerves,  which 
will  be  given  hereafter,  I  would  observe,  that  they  pass  through  the  foramina  and  canals 
of  the  cribriform  plate  of  the  ethmoid  bone,  at  the  same  time  becoming  enveloped  in 
fibrous  sheaths ;  that  they  enter  the  pituitary  membrane  by  its  external  surface ;  and 
that  they  expand  into  a  plexus  in  its  substance.  The  branches  of  these  nerves  cannot 
be  traced  lovi-er  than  the  middle  turbinated  bones  on  the  one  hand,  and  the  middle  of  the 
septum  on  the  other.  Thus,  while  the  upper  and  extremely  narrow  part  of  each  nasal 
fossa  {s,fig.  234)  is  the  essential  seat  of  the  sense  of  smell,  the  lower  and  much  wider 
part  only  gives  passage  to  the  air  during  the  act  of  respiration. 

Besides  the  special  nerve  of  smell,  the  pituitary  membrane  receives  other  nervous  fil- 
aments, all  of  which  are  derived  from  branches  of  the  fifth  nerve,  viz.,  from  the  internal 
nasal  and  the  frontal  branches  of  the  ophthalmic  division  of  that  nerve,  and  from  the 
spheno-palatine,  the  great  palatine,  the  vidian,  and  the  anterior  dental  branches  of  its 
second  or  superior  maxillary  division.  The  experiments  of  modern  physiologists  have 
shown  that  the  integrity  of  these  different  branches  of  the  fifth  pair  is  necessary  for  the 
perfect  possession  of  the  olfactory  sense.  This,  however,  is  very  different  from  saying 
that  the  seat  of  that  sense  is  in  the  branches  of  the  fifth  pair. 

The  membrane  which  lines  the  several  sinuses,  although  it  is  continuous  with  the  pi- 
tuitary membrane,  does  not  resemble  it  in  character ;  it  is  exceedingly  thin  and  trans- 
parent, and  appears  like  a  serous  rather  than  a  mucous  membrane  ;  that  it  is  a  mucous 
membrane,  is  satisfactorily  established  only  by  certain  pathological  f3,cts.  The  mucous 
membrane  of  the  sinuses  has  a  very  close  resemblance  to  the  conjunctiva.t 

The  Organs  of  Sight.  . 

The  eyes,  or  the  organs  of  sight,  are  situated  at  the  highest  part  of  the  face,  so  that 
they  are  enabled  to  explore  objects  at  a  distance. 

They  are  two  in  number  ;  but  they  co-operate  in  their  function  so  as  to  act  like  a  sin- 
gle organ.  The  result  of  this  is,  that  vision  is  rendered  more  certain,  and  its  field  of 
operation  more  extensive,  at  the  same  time  that,  from  the  unity  of  action  of  both  eyes, 
it  is  single. 

The  eyes  are  protected  by  the  orbital  cavities  in  which  they  are  contained  ;  they  are 
covered  by  the  eyelids,  and  these  are  surmounted  by  the  eyebrows.  They  are  surround- 
ed by  six  muscles,  by  which  they  can  be  moved  in  all  directions  ;  they  are  divided  into 

*  It  was  in  the  pituitary  membrane  of  the  calf  that,  about  ei  jht  vears  ago,  I  first  accidentally  injected  th*- 
tuperficial  lymphatic  network.  '      "  t  See  note,  p.  648. 


646  NEUROLOGY. 

the  straight  and  the  oblique  muscles.  There  is  also  a  secreting  a{5paratus,tKeapparafti# 
of  the  lachrymal  passages,  the  secretion  from  which  lubricates  the  anterior  surface  of  the 
ball  of  the  eye,  and  facilitates  the  exercise  of  its  functions. 

The  study  of  the  organ  of  sight,  therefore,  is  not  limited  to  that  of  the  eyes  alone, 
but  includes  that  of  the  means  of  protection,  viz.,  the  orbital  cavities  (see  Osteology), 
the  eyelids,  and  the  eyebrows  ;  that  of  the  muscles,  or  moving  organs  ;  and  that  of  the 
lachrymal  passages,  or  lubricating  apparatus.  These  accessory  parts,  or  appendages  of 
the  organ  of  vision,  have  been  collectively  named  by  Haller  the  tutamina  oculi.  We  shall 
commence  our  description  with  them. 

The  Eyebrows. 

The  eyebrmjos  are  two  arched  ridges,  which  are  covered  with  short  stiff  hairs,  that  are 
directed  from  within  outward,  and  overlap  each  other ;  the  eyebrows  are  situated  at 
the  lower  part  of  the  forehead,  and  form  the  boundary  of  the  upper  eyelid.  Their  direc- 
tion corresponds  precisely  with  that  of  the  orbital  arch.  The  hairs  upon  them  are  more 
numerous,  and  longer  at  the  inner  extremity,  which  is  called  the  head,  than  at  the  outer, 
which  is  denominated  the  tail  of  the  eyebrow.  The  heads  of  the  two  eyebrows  are  sep- 
arated from  each  other  by  an  interval  which  corresponds  to  the  root  of  the  nose  ;  some- 
times, however,  they  are  blended  together. 

Structure. — The  skin  in  which  the  hairs  of  the  eyebrow  are  implanted  is  thick,  and 
very  closely  united  beneath  to  a  muscular  layer  formed  by  the  frontalis,  the  orbicularis 
palpebrarum,  and  the  corrugator  supercilii,  the  last-named  muscle  being  situated  beneath 
the  other  two.  The  orbital  and  superciliary  arches  serve  as  a  basis  to  support  the  eye- 
brows ;  the  nerves  of  these  parts  are  very  numerous,  and  are  derived  from  the  facial  and 
the  fifth  nerves  ;  their  vessels  arise  from  the  ophthalmic  and  temporal  arteries. 

Uses. — The  eyebrows,  which  give  a  peculiar  character  to  the  human  countenance,  pro- 
tect the  eye,  and,  when  depressed  in  front  of  it,  intercept  a  great  number  of  the  rays  of 
light ;  they  assist  in  a  remarkable  degree  in  giving  expression  to  the  face. 

The  Eyelids. 

The  eyelids  are  two  movable  and  protecting  curtains,  placed  in  front  of  the  ball  of  each 
eye,  which  they  conceal  or  leave  uncovered,  according  as  they  are  in  a  state  of  approx- 
imation or  separation. 

The  eyelids  are  two  in  number — a  superior  and  an  inferior.  In  a  great  number  of  ani- 
mals there  is  a  third  eyelid,  of  which  merely  a  trace  exists  in  man.  The  eyelids  are 
large  enough  to  close  the  base  of  the  orbit  completely,  and  to  intercept  entirely  the  pas- 
sage of  light. 

Each  of  the  eyelids  presents  for  our  consideration  a  cutaneous  surface,  which  is  con- 
vex, and  marked  with  concentric  semilunar  folds  that  become  effaced  when  the  lids  are 
closed  ;  an  ocular  surface  {fig.  235),  which  is  concave,  is  accurately  moulded  upon  the 
ball  of  the  eye,  and  presents  a  series  of  yellowish  vertical  lines,  formed,  as  we  shall  see, 
by  the  Meibomian  glands  ;  an  adherent  border,  which  is  indicated  by  the  orbital  arch  in 
the  upper  eyelid,  but  is  less  clearly  defined  in  the  lower  lid,  in  which  it  is  continuous 
with  the  cheek ;  lastly,  a  free  border,  or  margin,  which,  in  both  eyelids,  is  straight  when 
the  lids  are  closed,  and  curved  when  they  are  open  :  in  the  latter  position  they  enclose 
an  elliptical  space  {rima  palpebrarum),  the  dimensions  of  which  vary  in  different  persons, 
and  hence  give  rise  to  the  expressions  large  eyes  and  small  eyes,  which  have  no  refer- 
ence to  the  actual  size  of  the  globe  of  the  eye,  but  merely  to  the  size  of  that  part  which 
is  exposed  to  view.  The  free  margins  of  the  eyelids  are  not  cut  obliquely  from  before 
backward,  so  as  to  intercept,  when  they  are  closed,  a  three-sided  interval  or  channel, 
which  is  completed  behind  by  the  globe  of  the  eye,  and  which  is  supposed  to  become 
larger  from  without  inward,  in  order  to  conduct  the  tears  towards  the  larchrymal  punc- 
ta.  On  the  contrary,  these  margins  are  cut  horizontally  from  before  backward  (see  sec- 
tion,^^.  240) ;  and  when  approximated,  they  leave  a  narrow  fissure  between  them,  which 
may  serve  as  a  channel  for  the  tears  during  sleep,  quite  as  well  as  the  three-sided  canal 
which  is  generally  supposed  to  exist. 

The  margins  of  the  eyelids,  moreover,  are  tolerably  thick,  and  are  ftirnished  at  their 
anterior  hp  with  three  or  four  rows  of  hard,  stiff,  and  curved  hairs,  which  are  more  nu- 
merous and  longer  on  the  upper  than  on  the  lower  eyelid,  and  at  the  middle  than  at  either 
end  of  each  :  these  are  the  eyelashes.  Their  direction  is  worthy  of  notice  :  in  the  upper 
eyelid  they  are  at  first  directed  downward,  and  are  then  curved  upward,  so  as  to  de- 
scribe an  arc  having  its  concavity  turned  upward  ;  the  eyelashes  of  the  lower  lid  have 
just  the  opposite  arrangement.  From  this  it  follows,  that  the  convexities  of  the  eye- 
lashes of  the  two  lids  are  turned  towards  each  other  ;  and  thus,  when  the  eye  is  shut, 
they  touch  each  other  without  being  able  to  interlace.  Serious  inconvenience  is  pro- 
duced when  the  eyelashes  deviate  from  their  proper  course,  and  are  turned  inward ; 
When  the  eyelashes  are  wanting,  the  free  margins  of  the  lids  are  attacked  with  chronic 
inflammation.  Along  the  posterior  lip  of  the  free  margin  of  each  eyelid,  or,  rather,  along 
the  angular  ridge  formed  by  the  union  of  that  margin  with  the  posterior  surface  of  the 


THE    EYELIDS.  Q47 

lid,  are  placed  a  very  regular  series  of  foramina  {figs.  235,  236),  from  which  the  sebace 
ous  matter  secreted  by  the  Meibomian  glands  may  be  expressed  in  masses  having  the 
form  of  small  worms. 

At  the  junction  of  the  external  five  sixths  with  the  internal  sixth  of  the  free  margins 
of  the  two  eyelids  are  found  two  very  remarkable  tubercles,  the  lachrymal  papillcB  or  tu- 
bercles  {a,fi^.  239 ;  also  seen  in/^«.  235,  236),  each  of  which  is  perforated  by  an  open- 
ing, visible  to  the  naked  eye ;  these  openings  are  the  puncta  lachrymalia,  the  orifices 
of  the  corresponding  lachrymal  canals.  That  part  of  the  free  margin  of  each  eyelid 
which  is  on  the  inner  side  of  the  corresponding  lachrymal  papilla  is  straight,  rounded, 
and  destitute  of  hairs  or  follicular  orifices  :  in  the  space  enclosed  between  this  part  of 
the  eyelids,  and  called  lacv^  lachrytnalis,  is  situated  the  caruncula  lachrymalis  (*,  fig.  239). 
The  upper  eyelid,  moreover,  is  twice  as  deep  as  the  lower  ;  so  that,  when  depressed, 
it  descends  below  the  transverse  diameter,  or  equator  of  the  eye,  to  use  an  expression 
invented  by  Haller.  • 

The  terms  angles  of  the  eye,  or  commissures  of  the  eyelids,  are  applied  to  the  angles 
formed  by  the  junction  of  the  extremities  of  the  free  margins  of  the  eyelids.  The  ex- 
ternal angle,  external  or  temporal  commissure  (b,  fig.  239),  is  also  named  the  little  angle 
(canthus  minor).* 

The  internal  angle,  internal  or  nasal  commissure  (e),  improperly  cedled  the  great  angle 
of  the  eye  {canthus  major),  corresponds  to  the  posterior  border  of  the  ascending  process  ol 
the  superior  maxillary  bone. 

Structure  of  the  Eyelids. — ^The  constituent  parts  of  the  eyelids  are,  the  tarsal  cartilages, 
a  fibrous  membrane,  a  muscular  layer,  two  integumentary  layers,  one  mucous  and  the 
other  cutaneous,  and  certain  follicles,  with  vessels,  nerves,  and  cellular  tissue. 

The  tarsal  cartilages,  which  resemble  in  their  use  the  cylinders  of  wood  attached  to 
the  bottom  of  a  map  or  diagram,  to  prevent  it  from  hanging  in  folds,  are  two  in  number, 
one  for  each  eyelid ;  they  are  cartilaginous  plates,  situated  within  the  free  margin  and 
the  contiguous  portion  of  the  lids.  The  tarsal  cartilage  of  the  upper  eyelid  (a,  figs.  235, 
236)  is  semilunar ;  that  of  the  lower  eyelid  {h)  has  the  form  of  a  small,  narrow  band ; 
neither  of  them  occupies  the  entire  length  of  the  corresponding  lid.  Their  anterior  sur- 
face is  convex,  and  is  covered  by  the  fibres  of  the  orbicularis  palpebrarum  muscle.  Their 
posterior  surface  {fig.  235)  corresponds  to  the  conjunctiva,  and  is  closely  adherent  to  it. 
The  Meibomian  glands  are  situated  between  the  conjunctiva  and  the  cartilage,  or,  rath- 
er, in  the  substance  of  the  cartilage. 

The  adherent  border  of  each  tarsal  cartilage  is  thin,  and  affords  attachment  to  the 
fibrous  membrane  of  the  lids ;  the  adherent  border  of  the  cartilage  of  the  upper  eyelid, 
which  is  convex,  also  gives  attachment  to  the  levator  palpebrae  superioris  muscle.  The 
free  margins  of  these  cartilages  are  their  thickest  parts,  and  occasion  the  thickness  of 
the  free  margins  of  the  eyelids,  t 

The  cutaneous  layer  is  remarkable  for  its  excessive  tenuity  and  semi-transparency : 
the  eyelashes  are  appendages  of  this  part  of  the  integument. 

The  cellular  layer  is  no  less  remarkable  for  the  absence  of  fat  than  for  its  extreme 
delicacy :  it  is  the  type,  indeed,  of  serous  cellular  tissue,  and  is  frequently  the  seat  of 
serous  infiltrations. 

The  muscular  layer  is  formed  by  the  palpebral  portion  of  the,  orbicularis  muscle,  the 
pale  colour  of  which,  as  I  have  already  noticed,  contrasts  with  the  dark-red  hue  of  the 
orbital  portion  of  the  same  muscle.  Besides  this,  the  upper  eyelid  has  an  extrinsic  mus- 
cle, the  levator  palpebrce  superioris  {a,  fig.  237),  the  tendon  of  which,  however,  is  alone 
concerned  in  the  formation  of  that  eyelid,  by  being  attached  to  the  upper  border  of  the 
corresponding  tarsal  cartilage. 

The  fibrous  layer  consists  of  a  fibrous  membrane,  which  arises  from  the  margin  of  the 
orbit,  and  is  attached  to  the  corresponding  borders  of  the  tarsal  cartilages.  This  mem- 
brane is  very  strong  and  unyielding  in  the  outer  half  of  the  base  of  the  orbit,  but  dimin- 
ishes in  thickness  towards  the  inner  half  of  that  base,  especially  on  the  inner  portion  of 
the  upper  eyelid,  where  it  degenerates  into  cellular  tissue. 

The  term  ligament  of  the  external  canthus  might  be  applied  to  a  fibrous  raphe,  which 
extends  horizontally  from  that  angle  to  the  base  of  the  orbit.  This  raphe  bifurcates  op- 
posite the  outer  canthus,  so  as  to  become  attached  to  the  outer  end  of  each  tarsal  car- 
tilage, and  it  exactly  corresponds  to  the  tendon  of  the  orbicularis  palpebrarum,  which  is 
situated  at  the  inner  canthus,  and  which  is  also  bifurcated,  to  join  the  inner  ends  of  the 
same  cartilages. 

(hi  cutting  through  this  raphe,  some  very  strong  fibrous  bundles  are  exposed,  which 
arise  from  the  external  wall  of  the  orbit,  and  spread  out  into  the  substance  of  the  upper 
eyelid. 

*  The  external  commissure  does  not  correspond  to  the  outer  extremity  of  the  transverse  diameter  of  th* 
base  of  the  orbit,  but  is  situated  about  three  lines  nearer  to  the  nose ;  hence  the  necessity  of  dividing  this 
commissure  in  extirpation  of  the  eye. 

t  [The  substance  of  the  tarsal  cartilages  differs  from  that  of  ordinary  cartilage  in  being  more  opaque,  and 
also  in  having  a  few  microscopic  filaments  scattered  through  it ;  in  this  respect  approaching  in  character  to 
fibro-cartilage.] 


648  NEUROLOGY. 

The  expanded  tendon  of  the  levator  palpebrae  superioris,  which  is  subjacent  to  the 
fibrous  layer,  completes  the  fibrous  structure  of  the  upper  eyelid.  The  tarsal  cartilages 
and  the  fibrous  layer  are  situated  upon  the  same  plane. 

The  mucous  layer,  or  palpebral  conjunctiva,  consists  of  a  membrane  which  lines  the 
posterior  surface  {fig.  235)  of  the  eyelids,  and  is,  moreover,  extended  over  the  globe  of 
tig.  235.  the  eye.     This  membrane  is  called  the  conjunctiva,  or  tunica 

adnata,  because  it  connects  the  eyelids  with  the  ball  of  the  eye. 
In  order  to  facilitate  our  description,  we  shall  suppose  it  to 
commence  at  the  free  margin  of  the  upper  eyelid  (a',  fig.  240), 
where  it  is  continuous  with  the  skin  :  having  covered  the  whole 
thickness  of  this  margin,  it  then  lines  the  posterior  surface  of 
the  tarsal  cartilage  (c'),  to  which  it  is  intimately  adherent,  and 
continues  in  the  same  direction  as  far  as  beneath  the  orbital 
arch.  At  this  point  it  is  refldfcted  upon  the  anterior  surface  of 
the  globe  of  the  eye,  so  as  to  form  a  cul-de-sac  between  that  organ  and  the  eyelid :  upon 
the  eyeball,  where  it  is  called  the  ocular  conjunctiva,  it  adheres  to  the  sclerotic  coat  by 
means  of  cellular  tissue,  which  is  at  first  loose,  but  gradually  becomes  closer  and  closer  as 
it  approaches  the  transparent  cornea.  Upon  the  cornea  (d')  its  adhesion  is  so  intimate 
that  some  anatomists  have  denied  its  existence  in  that  situation.  In  fact,  it  can  only  be 
anatomically  demonstrated  in  the  healthy  state  upon  the  margin  of  the  cornea,  but  its  ex- 
istence over  the  whole  of  that  part  of  the  eye  is  shown  in  some  diseases.  After  having 
covered  the  anterior  and  inferior  part  of  the  sclerotic  (c"),  the  conjunctiva  is  reflected 
upon  the  posterior  surface  of  the  lower  eyelid  (b'),  lines  its  tarsal  cartilage,  covers  its 
free  margin,  and  then  becomes  continuous  with  the  skin.  On  the  inner  side  of  the  ball 
of  the  eye  the  conjunctiva  forms  a  small  semilunar  fold,  the  plica  semilunaris  (e,  figs. 
235,  239),  which  has  its  concavity  turned  outward,  and  which  may  be  regarded  as  the 
vestige  of  the  third  eyelid  found  in  animals  :  it  is  misnamed  the  membrana  nictitans  (la 
membrane  clignotante).  On  the  outer  side,  the  conjunctiva  dips  between  the  eyelids 
and  the  ball  of  the  eye,  and  forms  a  deep  cul-de-sac.  Opposite  the  lachrymal  papillae 
the  conjunctiva  passes  into  the  puncta,  and  Hues  the  lachrymal  passages. 

From  what  has  been  stated  above,  it  will  be  seen  that  the  conjunctiva  would  form  a 
shut  sac,  like  the  serous  membranes,  if  the  eyelids  were  supposed  to  be  united.  Like 
the  serous  membranes,  it  covers  two  surfaces  that  rub  one  upon  the  other.  Its  tenuity, 
its  transparency,  and  the  filamentous  adhesions  which  are  sometimes  observed  between 
its  contiguous  surfaces,  have  induced  some  anatomists  to  place  this  membrane  among 
the  serous  rather  than  the  mucous  membranes  ;  but  its  continuity  with  the  skin,  its  ex- 
treme vascularity,  and  its  uses,  which  require  it  to  be  in  contact  with  the  air,  prove  that 
it  should  be  retained  among  the  latter  class  of  membranes.* 

The  glands  found  in  the  eyelids  consist  of  an  appendage  of  the  lachrymal  gland,  which 
will  be  described  with  it,  of  the  Meibomian  glands,  and  of  the  caruncula  lachrymalis. 
The  Meibomian  glands  (m  m,  fig.  236)  are  situated  upon  the  posterior  surface  of  both 
Fig.  236.  eyelids,  opposite  the  tarsal  cartilages ;  they  resemble  yellowish 

vertical  and  parallel  lines,  sometimes  straight  and  sometimes 
curved ;  their  length  is  proportioned  to  the  depth  of  the  cartilages, 
and  they  never  project  upon  the  inner  surface  of  the  eyelids.  Each 
of  these  lines,  of  which  there  are  from  thirty  to  forty  in  each  eye- 
lid, consists  of  a  tortuous  canal,  folded  upon  itself  a  great  number 
of  times,  and  having  a  considerable  number  of  small  follicles  open- 
ing into  it  on  each  side.  All  these  canals  open  very  regularly  upon 
the  posterior  lip  of  the  free  margin  of  the  lid  by  a  row  of  orifices 
arranged  in  a  single  line.  I  have  never  seen  two  rows  of  openings,  as  Zinn  states  he 
has  observed.  If  the  eyelids  be  compressed  over  the  tarsal  cartilages  by  a  pair  of  pin- 
cers, masses  of  a  waxy  substance  exude  from  these  orifices,  having  the  form  of  small 
worms  twisted  frequently  upon  themselves.  Sometimes  these  small  linear  canals  com- 
municate with  each  other  opposite  the  adherent  border  of  the  tarsal  cartilage  ;  at  other 
times  they  bifurcate.  It  is  the  waxy  sercetion  from  the  Meibomian  glands  which  pre- 
vents the  tears  from  trickling  in  front  of  the  eyehds.  These  glands  are  lodged  in  the 
deep  grooves  in  the  tarsal  cartilages ;  they  are,  therefore,  as  visible  upon  the  external 
as  the  internal  surface  of  the  cartilages. 

The  Meibomian  glands  belong  to  the  class  of  sebaceous  follicles,  and  form  a  transition, 
as  it  were,  from  follicles  to  glands. 

The  caruncula  lachrymalis  {c,fig.  235,*  fig.  239)  consists  of  a  small,  oblong  group  of 
follicles,  situated  at  the  inner  angle  of  the  eyelids,  and  on  the  inner  side  of  that  semilu- 
nar fold  of  the  conjunctiva,  which  we  have  spoken  of  as  the  trace  of  a  third  eyelid.  It 
is  about  the  size  of  a  grain  of  wheat.    It  is  interposed  between  the  free  margins  of 

*  The  absence  of  villi  has  been  stated  as  characteristic  of  the  conjunctiva ;  but  villi  or  papillae  are  found 
■pon  that  portion  which  lines  the  superior  tarsal  cartilage. 

[The  epithelium  of  the  conjunctiva  is  squamous,  and  consists  of  several  layers  :  according  to  Henl6,  it  i* 
ciliated  upon  the  inner  surface  of  the  eyelid  ;  but  cilia  have  not  been  observed  upon  the  eyeball.] 


THE   MUSCLES   OF  THE    EYE.  6^ 

tiie  eyelids,  in  that  part  of  those  margins  which  extends  between  the  lachrymal  tuber- 
cles and  the  internal  commissure  ;  but  it  is  upon  a  plane  posterior  to  these  margins,  so 
that  it  does  not  prevent  their  mutual  contact.  It  is  covered  by  a  fold  of  the  conjunctiva, 
which  gives  it  a  reddish  aspect ;  it  presents  a  great  number  of  openings,  through  which 
a  waxy  secretion  exudes,  and  projecting  from  it  are  several  small  hairs,  which  may  be- 
come so  long  as  to  produce  ophthalmia.  The  caruncula  lachrymalis  is  composed  of  se- 
baceous follicular  glands,  of  the  same  nature  as  the  Meibomian  glands.  It  was  for  a 
long  time  considered  to  be  a  second  lachrymal  gland.  In  order  to  obtain  a  good  view 
of  the  orifices,  and  of  the  light-coloured  and  sometimes  very  numerous  hairs  of  the  carun- 
cula lachrymalis,  that  body  should  be  covered  with  ink  or  a  solution  of  carmine,  and 
then  examined  with  a  lens. 

Vessels  and.  Nerves  of  the  Eyelids. — The  arteries  are  the  internal  and  external  palpe- 
bral branches  of  the  ophthalmic,  and  the  palpebral  branches  of  the  temporal,  infra-orbital, 
and  facial  arteries.  I  have  already  said  that  the  palpebral  arteries  form  two  arches,  one 
for  each  eyelid. 

The  veins  have  the  same  name,  follow  the  same  direction,  and  open  into  the  corre- 
sponding venous  trunks. 

The  nerves  are  derived  from  two  sources,  viz.,  the  facial  and  the  fifth  nerve. 

Uses. — The  eyelids  protect  the  eye  from  the  action  of  light  and  air,  and  of  any  parti- 
cles floating  in  the  latter ;  by  a  sweeping  movement,  they  clean  the  surface  of  the  or- 
gan, over  which  they  also  spread  the  lachrymal  fluid,  which  serves  as  a  protection  to  the 
eyeball  against  the  action  of  the  air.  The  eyelids,  from  their  capability  of  being  inter- 
posed between  the  eye  and  external  objects,  place  the  exercise  of  vision  under  the  con- 
trol of  the  will. 

The  Muscles  of  the  Eye,  and  the  Levator  Palpebrce  Superioris. 

The  muscles  of  the  eye  are  six  in  number,  and  are  distinguished  into  the  straight  and 
the  oblique.  There  are  four  straight  and  two  oblique  muscles.  With  these  we  shall 
also  describe  the  levator  palpebrae  superioris. 

Dissection. — Remove  the  roof  of  the  orbit  by  two  cuts  with  the  saw,  meeting  each  oth- 
er at  an  acute  angle  opposite  the  optic  foramen  ;  be  careful  that  the  inner  cut  does  not 
injure  the  cartilaginous  pulley  of  the  superior  oblique  muscle.  Dissect  the  origins  of 
these  several  muscles  from  the  deepest  part  of  the  orbit  with  the  greatest  care.  They 
are  arranged  completely  round  the  optic  nerve  (o,  figs.  237,  238)  and  the  motor  oculi 
nerves.  Those  which  arise  above  the  optic  nerve  are  attached  to  the  dura  mater  and 
periosteum,  but  not  to  the  bone ;  but  those  which  arise  below  the  nerve  adhere  more 
closely  to  the  bone.  The  inferior  or  small  oblique  muscle  is  the  only  one  which  does 
not  arise  from  the  bottom  of  the  orbital  cavity. 

The  Levator  Palpehra  Superioris. 

The  levator  paipebra  superioris  (a,  figs.  237,  238),  much  thinner  and  narrower  than  the 
rectus  superior,  which  is  subjacent  to  it,  arises  from  ^^    237. 

the  bottom  of  the  orbit,  at  the  upper  part  of  the  mar- 
gin of  the  optic  foramen,  or,  rather,  from  the  fibrous 
sheath  given  oflT  from  the  dura  mater  around  the  op- 
tic nerve.  It  arises  by  short  and  radiated  tendinous 
fibres,  to  which  the  fleshy  fibres  succeed,  in  the  form 
of  a  thin,  flat  muscle,  that  passes  outward  in  a  line 
parallel  with  the  axis  of  the  orbit,  is  reflected  upon 
the  globe  of  the  eye,  and  ends  in  an  aponeirrotic  ex- 
pansion, which  is  inserted  in  the  upper  border  of  the 
tarsal  cartilage  of  the  upper  eyelid 

Relations. — It  is  covered  by  the  periosteum  of  the 
roof  of  the  orbit,  it  is  covered  obliquely  at  its  origin 
by  the  ophthalmic  nerve,  and  it  covers  the  superior  rectus  muscle. 

Action. — ^This  muscle  raises  the  upper  eyelid,  and  draws  it  backward,  so  that  the  up- 
per border  of  the  eyelid  is  concealed  under  the  orbital  arch. 

The  Rectus  Superior,  or  Levator  Oculi. 

The  superior  rectus  (5)  has  two  very  distinct  origins.  The  first  resembles  that  of  the 
levator  palpebrae  superioris  in  being  from  the  upper  part  of  the  fibrous  sheath  of  the  optic 
nerve,  but  it  is  on  a  lower  plane  than  that  muscle  ;  the  second  is  from  the  inner  margin 
of  the  sphenoidal  fissure,  i.  e.,  between  that  fissure  and  the  optic  foramen.  The  latter 
origin,  which  is  continuous  with  those  of  the  external  rectus,  appears  to  take  place  from 
the  sheath  furnished  by  the  dura  mater  to  the  third  cranial  or  motor  oculi  nerve. 

The  fleshy  fibres  arising  from  this  radiated  tendon  form  a  flat  bundle,  which  passes  for- 
ward and  outward  in  the  direction  of  the  axis  of  the  orbit,  and  is  reflected  upon  the  eye- 
ball, where  it  becomes  converted  into  a  broad  and  thin  aponeurosis,  and  is  inserted  into 
the  sclerotic  coat,  at  a  short  distance  from  the  cornea. 

This  muscle,  like  all  the  other  recti,  is  in  relation  with  the  periosteum  of  the  orbit, 

4N 


«iv 


650  NEUROLOGY. 

from  which  it  is  separated  towards  the  inner  side  by  the  levator  palpebrae  superioris ;  it 
covers  the  optic  nerve  and  the  eyeball. 

The  Rectus  Inferior,  or  Depressor  Oculi. 
The  inferior  rectus  (c)  arises,  together  with  the  internal  and  external  recti,  by  a  common 
tendon,  called  the  tendon  or  ligament  of  Zinn,  which  is  attached  to  the  lower  half  of  the 
optic  foramen,  and  more  particularly  to  a  depression  which  is  seen  to  the  inner  side  of 
the  sphenoidal  fissure.  Almost  immediately  after  its  commencement  this  tendon  divides 
into  three  branches,  from  the  middle  one  of  which  the  inferior  rectus  muscle  arises,  and 
then  passing  horizontally  forward  and  outward,  is  reflected  upon  the  globe  of  the  eye, 
and  terminates  in  a  similar  manner  to  the  preceding  muscle. 

The  Rectus  Internus,  or  Adductor  Oculi. 
The  internal  rectus  {d)  has  two  very  distinct  origins :  one  from  the  tendon  of  Zinn,  the 
other  from  the  inner  side  of  the  fibrous  sheath  of  the  optic  nerve ;  the  latter  origin  is 
contmuous  with  those  of  the  superior  rectus.  From  these  points  it  passes  forward  along 
the  internal  wall  of  the  orbit,  is  reflected  upon  the  globe  of  the  eye,  and  terminates  like 
the  preceding  muscles. 

The  Rectus  Externus,  or  Abductor  Oculi. 
The  external  rectus  (e)  also  has  a  double  origin :  one  inferior,  derived  from  the  liga- 
ment of  Zinn ;  the  other  superior,  from  the  fibrous  sheath  of  the  sixth  cranial  or  abdu- 
cens  oculi  nerve,  and  continuous  with  the  external  origin  of  the  superior  rectus.  A 
fibrous  arch,  under  which  certain  veins  pass,  unites  these  two  origins,  and  also  serves 
as  a  point  of  attachment  to  the  muscular  fibres.  From  these  points  the  muscle  passes 
obhquely  forward  and  outward  along  the  external  wall  of  the  orbit,  is  reflected  upon  the 
eyebaU,  and  terminates  like  the  other  recti  muscles. 

General  Description  and  Action  of  the  Recti  Muscles. 

The  four  straight  muscles  of  the  eye  arise  from  the  bottom  of  the  orbit,  and  terminate 
upon  the  eyeball,  a  few  lines  from  the  cornea. 

They  all  have  the  same  form,  viz.,  that  of  a  long  isosceles  triangle,  having  its  base 
turned  forward  and  its  apex  backward.  Their  relations  are  also  similar  :  tlius,  they  cor- 
respond, on  the  one  hand,  to  the  periosteum  of  the  orbit,  and  on  the  other  to  the  optic 
nerve  and  the  globe  of  the  eye,  from  which  they  are  separated  by  some  fat  and  vessels. 

In  consequence  of  their  being  inserted  in  front  of  the  transverse  diameter  of  the  eye, 
they  are  all  reflected  upon  the  eyeball ;  this  fact  is  rendered  much  more  evident  when 
the  eye  is  drawn  in  an  opposite  direction  to  that  in  which  the  particular  muscle  under 
examination  would  act.  Their  tendons  are  surrounded  with  a  whitish,  and,  as  it  were., 
elastic  cellular  tissue,  by  which  the  movements  of  these  muscles  are  facilitated.* 

The  recti  differ  from  each  other,  both  in  length  and  thickness.  Thus,  the  internal 
rectus  is  the  shortest  and  thickest,  the  external  rectus  is  the  longest,  and  the  superior 
rectus  is  the  smallest. 

Action. — If  these  muscles  were  not  reflected  upon  the  globe  of  the  eye,  their  action 
would  be  simply  to  draw  it  forcibly  backward  towards  the  bottom  of  the  orbit ;  but,  in 
consequence  of  this  reflection,  they  can  give  it  a  rotatory  motion.  Thus,  the  superior 
and  inferior  recti  rotate  the  eyeball  upon  its  transverse  axis,  while  the  internal  and  ex- 
ternal recti  rotate  it  upon  its  vertical  axis.  After  either  of  these  effects  is  produced,  the 
eye  is  then  drawn  backward.  The  direct  movement  backward  is  produced  by  the  si- 
multaneous contraction  of  the  four  muscles. 

When  any  two  adjacent  recti  act  together,  the  eye  is  moved  in  the  diagonal  of  the  two 
forces  exerted  by  those  muscles  ;  and  hence  the  eye,  and  therefore  the  pupil,  can  pass 
over  all  the  radii  of  the  circle  represented  by  the  base  of  the  orbit ;  this  arrangement  is 
not  only  highly  favourable  to  the  exploratory  power  of  the  eye,  but  also  assists  in  placing 
the  function  of  vision  under  the  control  of  the  will,  since  it  enables  us  to  turn  away  the 
eyes  from  any  offensive  object.  The  straight  muscles  of  the  eye,  as  well  as  the  oblique 
muscles,  also  aid  in  expressing  the  passions  ;  and  hence  the  following  names  have  been 
given  to  them  by  the  ancients.  The  superior  rectus  is  called  superbus  (mirator,  Haller) ; 
the  inferior  rectus,  humilis ;  the  external  rectus,  indignatorius ;  the  internal  rectus,  amor 
torius  seu  bibitorius. 

Lastly,  it  has  been  supposed  that  the  muscles  of  the  eye,  by  compressing  that  organ, 
can  alter  the  distance  between  the  retina  and  the  crystalline  lens  ;  and  a  theory  to  ex- 
plain the  power  we  possess  of  adapting  the  eye  for  distinct  vision  at  different  distances 
has  even  been  constructed  on  the  supposed  possibility  of  this  compression. 

The  necessarily  simultaneous  and  co-ordinate  action  sometimes  of  the  same  muscle, 
and  sometimes  of  different  muscles  in  the  two  eyes,  is  a  remarkable  physiological  fact. 
Thus,  the  contraction  of  the  superior  rectus  of  the  right  eye  is  of  necessity  accompanied 
by  contraction  of  the  corresponding  muscle  of  the  left  eye  ;  while  the  contraction  of  the 
external  rectus  of  one  eye  is  accompanied  by  contraction  of  the  internal  rectus  of  the 

*  [Small  synovial  bursa  have  been  described  as  existing  between  tbese  tendons  and  the  globe  of  the  eye.] 


THE    OBLiaUE   MUSCLES    OF    THE    EYE. 


651 


other  eye,  and  vice  versa :  the  will  can  neither  prevent  nor  disarrange  these  co-ordinate 
contractions.  However,  even  without  much  practice,  it  is  possible  to  overcome  them, 
so  far  as  to  squint  by  endeavouring  to  look  at  the  nose. 

It  is  not  uninteresting  to  remark,  that  the  sixth  cranial  nerve,  or  the  abducens  oculi, 
is  destined  exclusively  for  the  external  rectus  muscle  ;  and  that  the  third  cranial  nerve, 
or  motor  oculi,  supplies  the  three  other  recti,  the  levator  palpebrae  superioris,  and  the 
obliquus  minor.  No  other  muscles  in  the  body  receive  such  large  nerves  in  proportion 
to  their  size  as  those  of  the  eye. 

Tke  Oblique  Muscles  of  the  Eye. 

These  are  two  in  number,  the  superior  or  great  oblique,  and  the  inferior  or  lesser  oblique. 
The  Obliquus  Superior. 

Tke  superior  or  great  oblique  muscle  of  the  eye  (/,  fig.  238)  is  a  long  filiform  muscle, 
which  is  reflected  over  a  pulley  or  trochlea,  and  hence  has  been  jv^.  238. 

termed  the  trocklearis  muscle  ;  it  arises  from  the  fibrous  sheath  of  the 
optic  nerve,  between  the  superior  and  internal  recti,  in  the  same 
manner  and  upon  the  same  plane  as  those  muscles  ;  from  this  point 
it  passes  forward  along  the  i^ngle  formed  by  the  junction  of  the  roof 
with  the  inner  wall  of  the  orbi,  and  forms  a  rounded  muscular  fas- 
ciculus, which  ends  in  a  rounded  tendon  near  the  cartilaginous  pulley 
intended  for  its  reception ;  the  tendon  passes  through  this  pulley,  is  i| 
reflected  upon  itself  at  an  acute  angle,  so  as  to  be  directed  down-  " 
ward,  outward,  and  somewhat  backward ;  gets  beneath  the  superior 
rectus,  where  it  spreads  out,  and  is  then  inserted  into  the  sclerotic 
coat  on  a  level  with  the  longest  transverse  diameter  of  the  eyebsil], 
and,  consequently,  farther  back  than  the  insertion  of  the  recti.  The 
superior  oblique  is  the  longest  muscle  of  the  eye 

The  trochlea,  or  pulley  of  the  superior  oblique,  is  a  small  cartilage, 
which  forms  five  sixths  of  a  short  cylinder  or  ring  ;  the  edges  of  this 
imperfect  cylinder  are  attached  to  the  slight  bony  ridges  which 
bound  a  depression  upon  the  superior  wall  of  the  orbit.  Its  attach- 
ment is  effected  by  means  of  loose  ligamentous  fibres,  so  that  the 
pulley  itself  has  a  certain  degree  of  mobility.  The  gliding  of  the 
parts  is  facilitated  by  a  synovial  membrane,  which  is  reflected  from  the  tendon  upon  the 
pulley,  and  is  prolonged  in  front  of  and  behind  the  latter.  Beyond  the  pulley,  a  whitish 
filamentous  tissue  takes  the  place  of  the  synovial  membrane. 

The  relations  of  the  superior  oblique  are  similar  to  those  of  the  superior  rectus. 

Action. — Like  aU  reflected  muscles,  the  superior  oblique  must  act  from  the  point  of  its 
reflection.  It  follows,  therefore,  that  this  muscle  rotates  the  eye  upon  itself  from  with- 
out inward,  that  is,  around  its  antero-posterior  axis.  From  the  oblique  direction  of  its 
t^don  from  before  backward,  after  it  is  reflected,  it  can  draw  the  eye  forward,  and 
tends  to  bring  it  out  beyond  the  orbit.  This  muscle  is  believed  to  assist  in  the  expres- 
sion of  the  tender  passions  (jnusculus  patheticus).  The  fourth  cranial  nerve,  also  called 
the  trochlear  or  pathetic  nerve,  is  destined  exclusively  for  this  muscle. 

The  Obliquus  Inferior. 

The  inferior  or  lesser  oblique  (g,  fig.  237,  238)  is  the  shortest  muscle  of  the  eye,  and 
the  only  one  which  does  not  arise  from  the  bottom  of  the  orbit ;  it  arises  from  the  inner 
and  anterior  part  of  the  floor  of  that  cavity,  and,  therefore,  from  the  orbital  surface  of  the 
superior  maxillary  bone,  immediately  behind  the  margin  of  the  orbit,  and  often  even 
from  the  lachrjnnal  sac.  From  this  origin  it  passes  backward,  in  the  form  of  a  flat  bun- 
dle, which  turns  round  the  lower  surface  of  the  globe  of  the  eye,  situated  at  first  between 
the  eyeball  and  the  inferior  rectus,  then  between  it  and  the  external  rectus,  and  at 
length  ends  in  an  aponeurotic  expansion,  which  is  blended  with  the  sclerotic,  near  the 
outer  border  of  the  superior  rectus. 

Its  insertion  into  the  sclerotic  is  farther  back  than  that  of  the  superior  oblique,  and, 
therefore,  much  farther  back  than  those  of  the  recti. 

Action. — It  rotates  the  eye  in  the  opposite  direction  to  the  superior  oblique.  Its  turn- 
ing round  the  lower  surface  of  the  eyeball  renders  its  action  extremely  effective.  From 
its  oblique  course  from  before  backward,  it  can  draw  the  eye  slightly  forward. 

The  Lachrymal  Passages. 

The  term  lachrymal  passages  includes  both  the  apparatus  for  secreting  and  that  for  con- 
veying away  the  tears,  consisting  of  a  secreting  organ,  named  the  lachrymal  gland ;  of 
excretory  ducts,  which  pour  out  the  tears  upon  the  conjunctiva  ;  and  of  a  second  set  of 
ducts,  intended  to  absorb  the  tears  and  convey  them  into  the  nasal  fossae,  comprising 
the  puncta  lachrymalia,  the  lachrymal  canals,  the  lachrymal  sac,  and  the  nasal  ducts.  Such 
is  the  order  in  which  we  shall  describe  this  apparatus. 


6S2  NEUROLOGY. 

The  Lachrymal  Gland.  .  ,  ^ 

The  lachrymal  gland  (glandula  innominata  of  the  ancients)  consists  of  two  very  distinct 
parts  :  an  orbital  portion,  situated  in  the  fossa  on  the  roof  of  the  orbit ;  and  a.  palpebral  por- 
tion, which  is  enclosed  in  the  substance  of  the  upper  eyehd. 

The  first  or  orbital  portion  (I,  fig.  207),  the  only  part  generally  described,  is  of  an  irreg- 
ular semi-ovoid  form,  having  its  long  diameter  placed  transversely.  It  varies  in  size  in 
different  subjects,  but  is  generally  about  as  large  as  a  filbert.*  Its  upper  surface  is  con- 
vex, and  corresponds  to  the  fossa  in  the  frontal  bone,  to  which  it  adheres,  especially  in 
front,  by  very  distinct  fibrous  bands  :  its  interior  surface  is  concave,  and  is  in  relation 
with  the  external  rectus,  and  with  a  small  part  of  the  superior  rectus.  Its  anterior  bor- 
der corresponds  to  the  orbital  arch,  or,  rather,  to  the  fibrous  membrane  of  the  eyelid,  im- 
mediately behind  which  it  is  situated  ;  hence  it  maybe  exposed  by  an  incision  along  this 
arch.    By  its  posterior  edge  it  receives  its  vessels  and  nerves. 

The  second  or  palpebral  portion,  though  continuous  with  the  first,  is  separated  from  it 
by  several  fibrous  bands.  It  forms  a  thin  granular  layer,  which  is  covered  and  concealed 
by  a  very  dense  lamina  of  fibrous  tissue  that  appears  to  be  prolonged  into  its  interior. 
This  palpebral  portion  occupies  the  outer  portion  of  the  upper  eyelid,  and  extends  almost 
as  far  as  the  upper  border  of  the  tarsal  cartilage. 

The  Excretory  Ducts  of  the  Lachrymal  Gland. — Before  the  discovery  of  these  excretory 
ducts,  it  was  only  by  inference  that  the  so-called  glandula  in7iominata  was  regarded  as 
the  secreting  organ  of  the  tears.  In  1661  Steno  discovered  these  ducts  in  the  sheep,  m 
which  animal  they  are  large  enough  to  admit  bristles.  He  described  thirteen  or  fourteen 
ducts.  The  difficulty  of  detecting  these  ducts  in  the  human  subject  is  sufficiently  proved 
by  the  fact  that  neither  Morgagni,  Zinn,  nor  Haller  could  ever  find  them ;  the  second 
Monro,  however,  succeeded  in  filling  them  with  mercury,  and  described  them  accurate- 
ly. They  are  from  ten  to  twelve  in  number  ;  they  run  parallel  to  each  other  beneath  the 
palpebral  conjunctiva,  and  open  upon  the  inner  surface  of  the  eyelid  by  a  corresponding 
number  of  orifices  {d,fig.  235),  placed  very  regularly  about  a  line  from  the  tarsal  cartilage, 
along  its  outer  half.  MM.  Chaussier  and  Ribes  have  succeeded  in  filling  them  with  mer- 
cury, by  injecting  them  from  the  gland  towards  the  eyelids.  Having  sought  in  vain, 
both  with  the  naked  eye  and  with  a  lens,  for  the  orifices  of  the  excretory  ducts  of  the 
lachrymal  gland  in  the  human  subject,  I  thought  of  dipping  the  eye  and  eyelids  in  a  so- 
lution of  carmine  or  slightly-diluted  ink  ;  and  I  then  saw  distinctly  a  dozen  openings  ar- 
ranged in  a  line  along  the  point  of  reflection  of  the  palpebral  conjunctiva  upon  the  eye- 
ball, and  occupying  the  outer  half  of  the  eyelid,  t 

The  Lachrymal  Puncta  and  Canals. 
The  puncta  lachrymalia  {a,  fig.  239),  two  in  number,  one  for  each  eyelid,  are  those  small 
Fig  239.  orifices  or  foramina  which  are  visible  to  the  naked  eye  in  the  centre 

of  the  lachrjonal  papillae  :  they  are  perfectly  circular,  are  always 
open,  and  are  directed  backward,  the  upper  one  being  turned  do*n- 
ward,  and  the  lower  one  upward.  These  openings,  which  are  ia^t 
apart  from  each  other  by  the  caruncula  lachrymalis,  are  the  cjq)il- 
lary  orifices  of  two  small  canals,  called  the  lachrymal  canals. 

The  lachrymal  canals  {I  I)  are  small  tubes,  extending  from  the 
puncta  lachrymalia  to  the  lachrymal  sac.  They  are  two  in  num- 
ber, a  superior  and  an  inferior,  each  being  somewhat  larger  than 
the  corresponding  lachrymal  punctum.  Their  angular  course  is  very  remarkable.  They 
pass  at  first  vertically,  the  superior  duct  upward,  and  the  inferior  duct  downward,  and 
after  a  short  course  they  bend  abruptly  at  right  angles,  run  inward,  and  open  by  separate 
orifices,  never  together,  into  the  anterior  and  external  part  of  the  lachrymal  sac.  The 
direction  of  the  second  portion  of  each  of  the  lachrymal  canals  varies  according  as  the 
eyelids  are  closed  or  open  :  the  duct  of  the  lower  eyelid  is  directed  somewhat  obliquely 
upward,  that  of  the  upper  eyelid  downward,  even  when  the  lids  are  completely  closed  ; 
but  they  are  both  very  oblique  when  the  eyelids  are  separated  ;  and  as  this  separation 
is  principally  due  to  the  elevation  of  the  upper  eyelid,  it  follows  that  the  obliquity  of  the 
upper  lachrjrmal  canal  must  be  very  well  marked. 

The  coats  of  the  lachrymal  canals  are  dense  and  elastic,  so  that  they  do  not  collapse 
when  empty,  and  must,  therefore,  act  as  capillary  tubes.  We  do  not  find  any  sphincter, 
either  at  their  palpebral  or  their  nasal  orifice ;  they  appear  to  be  formed  in  the  sub- 
stance of  the  free  margin  of  each  eyelid  ;  they  are  lined  by  a  prolongation  of  the  con- 
junctiva, and  are  covered  by  the  fibres  of  the  orbicularis  palpebrarum  muscle.  Behind 
them  are  found  some  muscular  fibres,  forming  a  dependance  of  a  small  fasciculus,  called 
the  muscle  of  Horner,  or  the  lachrymal  muscle,  which  was  believed  by  that  anatomist  to 
serve  in  drawing  the  lachrymal  ducts  inward. 

*  [It  has  all  the  anatomical  characters  of  a  compound  gland.] 

t  T  find  in  Haller  that  it  was  in  a  human  eye  which  had  been  macerated  for  some  time  in  water  tinged  with 
blood,  that  Monro  (Secundus)  discovered  these  orifices.  After  they  have  been  discovered,  it  is  easy  to  intro- 
duce the  end  of  the  rasrcurial  injecting  pipe  into  them. 


THE    LACHRYMAL    PASSAGES.  658 

The  Muscle  of  Homer. 

Dissection. — ^Turn  the  eyelids  inward,  and  carefully  remove  a  fibrous  layer  which  cov- 
ers this  muscle  upon  the  lachrymal  sac. 

This  small  muscle  arises  from  the  vertical  ridge  of  the  os  unguis,  which  forms  the  pos- 
terior border  of  the  lachrymal  groove ;  from  this  point  it  passes  transversely  outward 
along  the  posterior  tendon  of  the  orbicularis  palpebrarum,  and  divides  into  two  tongues, 
a  superior  and  an  inferior,  which  correspond  to  the  lachrymal  canals,  and  terminate  at 
the  respective  lachrymal  puncta. 

I  regard  these  fibres  as  a  dependance  of  the  orbicularis  palpebrarum. 

The  Lachrymal  Sac  and  Nasal  Duct,  or  Lachrymo-nasal  Canal. 

The  lachrymal  sac  and  nasal  duct  constitute  a  single  canal,  which  extends  from  the  up- 
per part  of  the  lachrymal  groove  to  the  inferior  meatus  of  the  corresponding  nasal  fossa. 

The  lachrymal  sac  (wi),  that  portion  of  the  lachrymo-nasal  canal  which  occupies  the 
lachrymal  groove,  represents  the  half  of  a  cylinder  terminating  above  in  a  cul-de-sac.  It 
is  buried,  so  to  speak,  in  the  substance  of  the  inner  wall  of  the  orbit,  immediately  be- 
hind the  margin  of  that  cavity,  and  is  in  relation  with  the  inner  angle  of  the  eyelids,  the 
caruncula  lachrymalis,  the  adipose  tissue  of  the  orbit,  and  the  tendon  of  the  orbicularis 
muscle.  The  last-named  relation  is  one  of  the  most  important  points  in  the  anatomy  of 
the  lachrymal  sac.  If  a  circular  incision  be  made  through  the  eyelids  from  their  outer 
aigle  along  their  adherent  borders,  and  the  lids  be  then  turned  inward,  by  then  careful- 
ly dissecting  the  tendon  of  the  orbicularis,  it  will  be  found  that  that  tendon  divides  into 
three  branches  ;  that  the  anterior  branch,  called  the  straight  tendon,  is  inserted  in  front 
of  the  ascending  process  of  the  superior  maxillary  bone  ;  that  the  posterior  branch,  which 
is  of  equal  size  with  the  anterior,  is  inserted  into  the  ridge  upon  the  os  unguis,  behind 
the  lachrymal  groove  ;  that  the  middle  branch  ascends  to  be  attached  to  the  upper  part 
of  the  lachrymal  groove  ;  and,  lastly,  that  the  lower  part  of  the  tendon  gives  off  a  fibrous 
expansion,  which  forms  the  outer  side  of  the  lachrymal  sac,  and  which  may  be  regard- 
ed as  a  fourth  tendinous  expansion.  The  muscle  of  Homer  lies  upon  the  posterior  of 
these  tendons,  and  must  be  regarded  as  a  portion  of  the  orbicularis  itself 

The  tendon  of  the  orbicularis  palpebrarum  corresponds  to  the  upper  part  of  the  lachry- 
mal sac,  only  its  cul-de-sac  projecting  above  the  tendon.  The  greatest  part  of  the  sac 
is,  therefore,  situated  below  it. 

The  internal  surface  of  the  lachrymal  sac  presents  the  ordinary  appearance  of  all  ca- 
nals lined  by  mucous  membrane  :  a  considerable  quantity  of  mucus  is  often  found  in  it. 
At  the  anterior  part  of  its  external  wall,  and  at  about  an  equal  distance  from  the  top  and 
bottom,  are  the  two  orifices  of  the  lachrymal  canals  ;  above,  is  the  narrow  cul-de-sac,  in 

hich  it  terminates  in  that  direction  ;  and  below,  it  becomes  continuous  with  the  nasal 
duct :  in  this  place  there  is  rather  frequently  found  a  semilunar,  sometimes  even  a  cir- 
cular valve  ;  this  is  the  kind  of  diaphragm  spoken  of  by  Zinn,  but  the  existence  of  which 
w^denied  by  Morgagni.     Haller  says  that  he  only  met  with  it  once. 

lachrymal  sac  consists  of  a  partly  bony  and  partly  fibrous  canal,  lined  by  a  mu- 
embrane.  The  bony  portion  of  this  canal  is  formed  by  the  groove  upon  the  as- 
ing  process  of  the  superior  maxillary  bone,  and  upon  the  os  unguis  ;  the  last-men- 
led  bone,  which  is  thin  and  pierced  with  foramina,  may  be  easily  perforated ;  and 
hence  the  facility  of  making  an  artificial  passage  for  the  tears.  The  lachrymal  sac  is 
opposite  to  the  middle  meatus  of  the  corresponding  nasal  fossa. 

The  fibrous  portion  forms  the  external  flattened  wall  of  this  canal ;  it  is  very  strong 
and  unyielding,  unless  to  long-continued  extension. 

The  slight  muscular  layer,  described  as  the  muscle  of  Horner,  may  be  regarded  as  be- 
longing to  the  lachrymal  sac :  this  muscle  is  itself  covered  by  a  layer  of  fibrous  tissue. 

The  lining  mucous  membrane  of  the  lachrymal  sac  is  reddish,  and,  as  it  were,  pulpy, 
and  closely  resembles  the  pituitary  membrane  ;*  from  its  close  attachment  to  the  peri- 
osteum of  the  walls  of  the  canal,  it  might  be  called  afibro-mucous  membrane. 

The  nasal  duct  (n),  which  may  be  said  to  be  formed  in  the  outer  wall  of  the  corre- 
sponding nasal  fossa,  extends  from  the  lachrjTnal  sac  to  the  anterior  part  of  the  inferior 
meatus  of  the  nose.  It  is  of  a  cylindrical  shape,  slightly  flattened  on  the  sides,  and  rath- 
er narrower  at  the  middle  than  at  its  extremities.  It  is  directed  vertically,  but  forms  a 
slight  curve,  having  its  concavity  turned  forward  and  outward.  It  may  be  also  readily 
conceived  that  the  relative  breadth  of  the  root  of  the  nose  must  affect  the  direction  of 
this  canal. 

It  corresponds,  on  the  inner  side,  to  the  middle  meatus  of  the  nose,  and  the  inferior  tur- 
binated bone  ;  on  the  outer  side,  to  the  maxillary  sinus,  from  which  it  is  separated  by  a 
very  thin  lamina  of  bone.  This  latter  relation  has  doubtless  led  one  anatomist  to  state 
that  the  nasal  canal  opens  both  into  the  maxiUary  sinus  and  the  nasal  fossa. 

The  nasal  canal  consists  of  a  bony  canal  lined  by  a  fibro-mucous  membrane  ;  the  bony 
canal  is  complete,  and  is  formed  by  the  superior  maxillary  bone,  the  os  unguis,  and  the 
inferior  turbinated  bone.    It  is  very  strong  in  the  part  formed  by  the  superior  maxillary 

*  See  note,  p.  654. 


654  NEUROLOGY. 

bone,  excepting  opposite  to  the  sinus  in  that  bone,  but  it  is  very  thin  and  fragile  where 
it  is  formed  by  the  os  unguis  and  inferior  turbinated  bone.  Its  lining  membrane  is  of  a 
fibro-mucous  structure  ;  it  adheres  very  slightly  to  the  walls  of  the  canal,  and  is  contin- 
uous, on  the  one  hand,  with  the  mucous  membrane  of  the  lachrymal  sac,  and,  on  the 
other,  with  the  pituitary  membrane.*  This  lining  membrane  is  often  prolonged  for  sev- 
eral lines  beyond  the  nasal  duct,  so  as  to  form  a  valvular  fold  (o).  Where  this  fold  ex- 
ists, the  inferior  orifice  of  the  nasal  duct  (see  r,fig.  233)  is  always  closed,  and,  there- 
fore, difficult  to  be  detected,  even  when  the  inferior  turbinated  bone  has  been  taken 
away  or  displaced,  so  that,  in  order  to  discover  it,  it  becomes  necessary  to  introduce  a 
probe  through  the  lachrymal  passages  from  above.  In  catheterism  of  thelift|J  duct 
from  below  upward,  according  to  the  method  practised  by  Laforest,  this  fold  ^Btocous 
membrane  must  of  necessity  be  torn.  ^fe 

It  has  been  stated  by  some  authors,  that  the  lower  orifice  of  the  nasal  duct  isp^e- 
ded  by  an  ampulla,  or  infundibuliform  dilatation.  I  have  met  with  this  disposition,  but 
regarded  it  as  morbid.  I  am  convinced  that  a  great  many  lachrymal  tumours  depend 
upon  contraction  or  obliteration  of  the  lower  orifice  of  this  canal. « 

The  Globe  of  the  Eye. 
The  globe  of  the  eye  {v,fig.  240)  is  situated  in  the  fore  part  of  the  orbital  cavity ;  it  is  retain- 
Fig.  240.  ed  in  this  situation  by  the  optic  nerve  (o),  the  straight 

and  oblique  muscles  {beg),  the  vessels,  the  conjunctifa 
(d),  and  the  eyelids  ;  these  parts,  however,  do  not  con- 
fine it  in  a  fixed  position,  but  allow  it  great  mobility.  In 
fact,  the  eye  can  be  rotated  around  all  its  axes,  and 
can  even  be  drawn  forward  and  backward  (see  Mus- 
cles of  the  Eye).  The  eyes  are  small  in  comparison  to 
the  orbital  cavities  ;  and  they  present  some  slight  dif- 
ferences as  to  size  in  different  persons,  which  have 
not  yet  been  properly  estimated.  The  common  terms. 
large  and  small  eyes  apply  less  to  the  eyeball  than  to 
the  opening  between  the  eyelids.  The  eye  is  propor- 
tionally larger  in  the  foetus  and  new-born  infant  than'in  the  adult  and  aged. 

Inform,  the  globe  of  the  eye  resembles  a  regular  spheroid,  to- the  front  of  which  r?  at- 
tached a  segment  of  a  smaller  sphere  {see  fig.  241) :  by  this  arrangement,  the  anjfero- 
posterior  diameter  of  the  organ  is  increased  to  the  length  of  eleven  lines,  whil^it^l^h- 
er  diameters  are  only  ten  lines.  It  is  said  that  the  form  of  the  eyeball  can  ' 
by  the  contraction  of  its  muscles,  but,  in  consequence  of  the  great  tension  of  tj 
the  alteration  produced  is  so  slight  tj^at  it  scarcely  deserves  to  be  mentioned. 

The  general  relations  of  the  eyeball  are  the  following :  in  front,  it  is  covere 
conjunctiva  and  the  eyelids,  which  defend  it  from  light  and  from  dust,  rather 
external  violence.     It  results,  also,  from  the  obliquity  of  the  margin  of  the  orbit,' 
the  outer  side,  the  eye  projects  considerably  beyond  the  bones.     In  every  other  pi 
its  surface  the  eye  rests  upon  an  elastic  cushion  of  fat  (//),  which  separates  it' 
the  muscles  and  nerves,  fills  up  all  intervals,  and  facilitates  the  movements  of  the  or^ 
The  absorption  of  this  fat  in  emaciated  individuals  causes  the  depression  of  the  eyej 
the  orbital  cavity.    A  membranous  cellular  tissue,  or,  rather,  a  rudimentary  sync 
membrane,  exists  between  the  eye  and  this  fat.  ., 

Structure. — Like  all  the  other  organs  of  the  senses,  the  eye  consists  essentially  of  a 
membrane  provided  with  a  special  nerve,  and  of  a  particular  apparatus,  placed  in  relation 
with  the  external  agent  by  which  the  organ  is  to  be  acted  upon.  In  the  organ  of  vision, 
the  sentient  membrane  is  the  retina,  which  is  the  immediate  seat  of  the  sense  of  sight ; 
the  other  parts  of  the  eyeball  form  nothing  more  than  a  very  comphcated  dioptric  instru- 
ment, a  dark  chamber,  in  which  the  rays  of  light  are  refracted,  and  concentrated  so  as 
to  form  a  vivid  image,  and  which  is,  moreover,  provided  with  a  movable  diaphragm  to 
regulate  the  number  of  rays  to  be  admitted. 

In  an  anatomical  point  of  view,  the  eye  is  said  to  consist  of  certain  membranes  and 
humours.  The  membranes,  counting  from  without  inward,  are  the  sclerotic  coat  and  cor- 
nea, the  choroid  coat  and  iris,  and  the  retina.  The  humours  are,  the  vitreous  body  and  its 
hyaloid  membrane,  the  crystalline  lens  and  its  capsule,  and  the  aqueous  humour. 

The  Sclerotic. 

Dissection. — Clean  the  globe  of  the  eye,  leaving  the  attachments  of  the  muscles  to  the 
sclerotic  coat ;  with  a  pair  of  strong  scissors  divide  this  coat  circularly  into  an  anterior 
and  posterior  portion,  taking  care  to  avoid  the  choroid  coat ;  turn  the  one  portion  for- 
ward and  the  other  backward.  It  is  easier  to  make  this  section,  without  injuring  the 
choroid,  upon  a  slightly  flaccid  eye  than  upon  one  which  is  perfectly  fresh. 

The  sclerotic  {aK%T]pdg,  hard),  or  the  opaque  cornea  {b,fig.  241),  is  the  outermost  of  the 

*  [The  epithelium  of  the  mucous  membrane  of  all  the  lachrymal  passages  is  columnar,  and,  according  to 
Henle,  is  provided  with  cilia,  although  Perkinj6  and  Valentin  failed  to  discover  them  in  these  situations.] 


THE    CORNEA.  655 

coats  of  the  eye,  and  forms,  as  it  were,  the  shell  of  that  organ ;  it  is  of  a  pearly- white 
colour,  and  very  stroag,;. it  is  perforated  behind  to  give  passage  to  the  optic  nerve  (o), 
and  presents  a  circular  opening  in  front  (from  a  to  a),  into  which  the  cornea  is  fitted. 

Its  external  surface  forms  the  outer  surface  of  the  eyeball,  and  therefore  has  the  same 
relations.  Thus,  it  is  covered  in  front  by  the  conjunctiva,  which  adheres  to  it  by  means 
of  very  loose  cellular  tissue,  that  is  liable  to  infiltration.  The  straight  and  oblique  mus- 
cles of  the  eye  are  implanted  into  it.  An  imperfect  or  rudimentary  synovial  capsule 
separates  it  from  the  cushion  of  fat,  and  gives  it  a  smooth  aspect. 

Its  internal  surface  has  a  dull,  rough  appearance,  very  different  from  that  of  its  exter- 
nal surface  :  it  is,  moreover,  of  a  deep-brown  colour,  from  the  choroid  pigment ;  it  cor- 
responds to  the  choroid  coat  (c),  and  is  united  to  it  by  a  very  delicate  cellular  tissue,  and 
by  the  ciliary  vessels.*  The  ciliary  nerves  run  from  behind  forward  between  the  scle- 
rotic and  the  choroid,  occupying  slight  grooves  upon  the  internal  surface  of  the  former. 
Both  the  ciliary  vessels  and  nerves  perforate  the  sclerotic  coat  very  obliquely. 

Structure. — ^The  sclerotic  is  one  of  the  thickest  and  strongest  fibrous  membranes  in 
the  body^  it  is  not  of  uniform  thickness  throughout ;  it  is  thickest  behind,  at  the  entrance 
of  the  optic  nerve,  and  thinnest  in  front,  near  the  cornea.  Like  all  the  fibrous  mem- 
branes, it  is  unyielding ;  and  on  this  depends  the  firmness  and  tense  condition  of  the 
globe  of  the  eye  :  it  is  also  the  cause  of  the  intense  pain  produced  by  inflammation  of 
the  interior  of  the  eye  and  by  certain  cases  of  hydrophthalmia. 

The  older  anatomists  considered  the  sclerotic  to  be  composed  of  two  layers,  the  inner 
of  which  was,  according  to  Zinn,  a  prolongation  of  the  pia  mater,  and,  according  to 
Meckel,  of  the  arachnoid.  But,  independently  of  the  fact  that  the  division  of  the  sclerot- 
ic into  two  layers  is  purely  artificial,  it  may  be  stated  that  neither  the  pia  mater  nor  the 
arachnoid  is  prolonged  upon  the  optic  nerve.  Lastly,  the  sclerotic  has  been  regarded  as 
a  continuation  of  the  dura  mater,  through  the  medium  of  the  neurilemma  of  the  optic 
nerve ;  and  this  view  is  supported  by  dissection,  which  shows  clearly  that  the  sheath 
furnished  by  the  dura  mater  to  the  optic  nerve  is  prolonged  upon  the  sclerotic.  It  has, 
moreover,  been  stated,  but  incorrectly,  that  the  anterior  part  of  the  sclerotic  has  an  ad- 
ditional layer,  formed  by  the  union  of  the  tendons  of  the  recti  muscles. 

The  sclerotic  is  composed  of  fibrous  bundles  which  interlace  in  all  directions. 

Its  use  is  especially  to  protect  the  globe  of  the  eye,  of  which  it  forms  the  covering  and 
determines  the  shape. 

.;-  The  Cornea. 

^' 

The  transparent  cornea  {a  a,  fig.  241)  completes  the  external  shell  of  the  eye  in  front : 
in  reference  to  the  sclerotic  coat,  it  represents  a  segment  of  a  smaller  sphere  superadded 
to  a  larger  sphere ;  its  circumference  is  circular,  or,  rather,  slightly  elliptical,  for  its 
transverse  diameter  is  half  a  line  longer  than  its  vertical  diameter. 

Its  anterior  surface  is  convex,  and  projects  forward  beyond  the  sclerotic  ;  it  is  covered 
by^he  conjunctiva,  which  adheres  to  it  so  closely,  that  the  existence  of  that  membrane 
v^^fm  it  has  Been  denied  by  some  anatomists.! 

■"Ij^o  great  a  convexity  of  the  cornea,  by  increasing  the  refracting  power  of  the  eye, 
^jgftasions  myopia,  or  short-sightedness. 

■  its  posterior  surface  is  concave,  and  forms  the  anterior  wall  of  the  anterior  chamber 
of  the  eye.  A  thin  membrane  (m)  covers  this  surface,  and  is  called  the  membrane  of  the 
aqueous  humour. 

The  circumference  of  the  cornea,  which  is  fitted  into  the  opening  in  the  front  of  the  scle- 
rotic, is  cut  obliquely,  so  that  its  external  surface  is  smaller  than  its  internal  surface ;  the 
oblique  edge  of  the  sclerotic,  to  which  it  corresponds,  is  sloped  in  the  opposite  direction. 

The  cornea  and  sclerotic  adhere  so  closely  that  they  were  for  a  long  time  regarded  as 
forming  but  one  coat ;  but,  independently  of  their  difference  in  appearance  and  texture, 
they  may  be  separated  by  boiling  or  by  long-continued  maceration. 

Structure. — The  cornea  is  thicker  than  the  sclerotic  :  it  may  be  separated  into  a  great 
number  of  lamellas,  united  by  very  thin  layers  of  cellular  tissue  ;  but  this  separation  is 
purely  artificial,  so  that  the  number  of  lamellae  is  indefinite.  The  thinnest  layer  of  fluid 
interposed  between  the  lamella;  is  sufficient  to  impair  the  transparency  of  the  cornea; 
maceration,  accordingly,  gives  it  a  milky  appearance.  The  opacity  of  the  cornea,  which 
occurs  in  some  cases  of  ophthalmia,  depends  upon  the  infiltration  between  the  lamellae 
of  a  certain  quantity  of  fluid,  after  the  absorption  of  which  the  cornea  recovers  its  ori- 
ginal transparency. 

No  vessels  can  be  shown  in  the  cornea,  even  by  the  aid  of  the  finest  injections  of  the 
arteries  and  veins  of  the  eye  :  its  superfi^cial  layer,  which  is  continuous  with  the  con- 
junctiva, contains  a  network  of  lymphatics  communicating  with  those  of  the  conjunc- 
tiva, and  capable  of  being  demonstrated  by  puncturing  any  part  of  the  superficial  layer  of 

*  See  note,  p.  656. 

t  A  careful  dissection,  especially  after  prolonged  maceration,  shows  the  continuity  of  the  most  superficial 
layer  of  the  cornea  with  the  conjunctiva.  A  malformation  sometimes  occurs  iu  which  oni^  part  of  the  cornea 
is  covered  by  a  prolongation  of  the  conjunctiva. 


656 


NEUROLOGY. 


the  cornea.     It  is  useless  to  introduce  the  tube  deeper,  for  the  lymphatic  network  is  en- 
tirely superficial. 

Uses. — The  transparent  cornea  is  the  first  medium  through  which  the  rays  of  light 
have  to  pass  ;  in  consequence  of  its  density  and  its  convexity,  it  refracts  the  rays  of  light, 
and  causes  them  to  converge.  The  density  of  the  cornea  is  the  same  in  different  per- 
sons ;  but  its  convexity  is  subject  to  variations,  upon  which  depend,  in  a  great  measure, 
the  states  of  myopia  (short  sight),  presbyopia  (long  sight),  and  natural  vision. 

The  Choroid  Coat,  and  the  Ciliary  Circle  and  Processes. 

The  choroid  (indicated  by  the  thick  black  hue,  c,Jlg.  241),  so  called  from  its  extreme 
vascularity,*  is  the  second  membrane  of  the  eye,  proceeding  from  without  inward  ;  it 
is  a  vascular  membrane,  covered  with  a  thick  layer  of  pigment :  it  exactly  lines  the 
sclerotic,  and  terminates,  like  it,  at  the  circumference  of  the  cornea. 

Its  external  surface  (c,  jigs.  242,  244)  adheres  to  the  schlerotic  by  means  of  the  ciliary 
vessels  and  nerves,  and  by  a  thin  and  very  delicate  cellular  tissue,  which  is  easUy  lacer- 
ated, and  when  raised  appears  like  a  spider's  web.+  This  surface,  when  magnified,  has 
a  fiocculent  appearance. 

Its  internal  surface  is  in  relation  with,  but  does  not  adhere  to,  the  retina  (r,  fig.  241),  by 
which  it  is  lined  nearly  throughout  its  whole  extent. 

Both  surfaces  of  the  choroid  are  covered  with  a  pigment,  which  resembles  the  pigment 
of  the  skin  of  negroes  ;  this  pigment  is  much  more  abundant  on  the  internal  than  on 
the  external  surface,  and  less  so  behind  than  in  front,  where  it  forms  a  thick  layer,  in 
the  form  of  a  zone  surrounding  the  corona  ciliaris. 

Upon  both  surfaces  are  found  innumerable  longitudinal  and  contorted  lines,  which 
correspond  to  the  vessels  of  the  choroid. 

In  a  great  number  of  animals,  in  the  ox,  for  example,  the  pigment  on  the  interned  sur- 
face of  the  choroid  at  the  back  of  the  eye  is  replaced  by  a  brilliant  metallic-looking  sub- 
stance called  the  tapetum.  When  deprived  of  its  pigment,  the  internal  surface  of  the 
choroid  presents  a  smooth  aspect,  and  is  not  fiocculent  like  the  external  surface.  It  is 
of  a  grayish- white  colour,  and  anteriorly,  where  it  is  covered  by  a  thick  layer  of  pigment, 
it  becomes  white  and  shining  when  the  pigment  is  removed. 

Behind,  the  choroid  is  pierced  by  a  circular  opening  for  the  passage  of  the  optic  nerve  ; 
in  front,  it  terminates  in  the  ciliary  circle  and  ciliary  processes,  which  must  be  regarded  as 
appendages  to  it. 

T'he  Ciliary  Circle. — The  ciliary  circle,  ring,  or  ligament  («,  fig,  241  ;   b,  figs.   242, 
fin.  ail,  244),  IS  a  circular  zone,  from  a  line  to  a 

J j_  line  and  a  half  in  breadth,  of  a  grayish  col- 

our, and  soft  consistence,  which  bounds 
the  choroid  coat  (c  c)  in  front.  It  is  of  con- 
siderable thickness.  Its  external  surface 
corresponds  to  the  sclerotic,  to  which  it  is 
slightly  adherent.  Its  internal  surface  Qpr- 
responds  to  the  ciliary  processes  (e,  fig. 
241) ;  by  its  outer  or  larger  border,  which 
is  distinguished  from  the  choroid  by  a  slight 
ridge,  it  receives  the  ciliary  nerves  (a  a, 
fig.  242),  which  bifurcate,  and  appear  to 
anastomose  with  each  other  before  they 
enter  the  substance  of  the  ciliary  circle  : 
by  its  lesser  or  inner  border,  wliich  corre- 
sponds to  the  iris  (i),  it  adheres  intimately 
to  the  circumference  of  the  cornea,  exactly  where  that  membrane  is  continuous  with  the 
sclerotic  (at  a  a,  fig.  241).  The  older  anatomists  called  this  structure  the  ciliary  liga- 
merU.  From  the  great  number  of  the  nerves  which  enter  the  ciliary  circle,  from  its  gray- 
ish colour,  and  its  pulpy  aspect,  modern  anatomists  have  regarded  it  as  a  nervous  gan- 
glion (annulus  gangliformis,  or  annular  ganglion,  Sammering). 

Fig.  242.  Some  anatomists  describe,  under  the  name  of  the  ciliary  canal, 

or  the  canal  of  Fontana,  a  very  small  and  extremely  narrow  cir- 
cular space  (u  V,  fig.  241),  which  is  formed  between  the  ciliary 
circle,  the  cornea,  and  the  sclerotic.  This  space  can  be  filled 
with  injection,  and  it  is  not  certain  that  it  is  not  the  cavity  of  a 
bloodvessel. 

The  Ciliary  Processes  and  the  Ciliary  Body. — If  the  back  part 

of  the  sclerotic,  choroid,  and  retina  be  cut  away,  or  even  if  the 

fc  globe  of  the  eye  be  merely  divided  into  an  anterior  and  posterior 

*  Choroid  is  synonymous  with  vascular. 

t  [A  serous  cavity  is  said  by  some  to  exist  betvreen  the  sclerotic  and  choroid ; 
the  lining  membrane  of  this  supposed  cavity  is  named  the  arachnoid  membrane 
of  the  eve.] 


THE  IRIS.  ^7 

half  by  a  circular  incision,  on  looking  into  the  anterior  half  a  perfectly  regular  radiated 
disc  {d,  Jig.  241 ;  a  b,  fig.  243)  will  be  seen  around  the  crystalline  lens.  This  disc,  which 
has  been  very  correctly  compared  to  a  radiated  flower,  is  called  the  ciliary  body,  or  cormia 
ciliaris  ;  each  of  the  rays  is  called  a  ciliary  process  or  ray  (rayon  sous-irien,  Chaussier). 
If,  after  a  correct  idea  of  the  arrangement  of  this  radiated  disc  has  been  obtained,  the 
choroid  coat  be  separated  from  the  humours  of  the  eye,  it  will  be  found  that  there  are  two 
perfectly  distinct  discs :  one  of  these  remains  attached  to  the  choroid  coat,  and  constitutes 
the  ciliary  disc  or  ciliary  body  of  the  choroid  (a  b,  fig.  243) ;  the  other  remains  attached  to  the 
vitreous  body  and  to  the  crystalline  lens,  and  is  the  ciliary  zone  of  pig,  243. 

Zinn,  which  may  be  termed,  after  M.  Ribes,  the  ciliary  processes 
of  the  vitreous  body  (a  b,fig.  248).  We  shall  now  describe  the  cil- 
iary processes  of  the  choroid  coat  only,  leaving  the  ciliary  pro- 
cesses of  the  vitreous  body  to  be  described  together  with  that  part 
of  the  eye. 

The  ciliary  processes  of  the  choroid  coat,  so  well  described  by 
Zinn,  who  enumerates  sixty  of  them,  are  regarded  as  so  many 
folds  of  the  internal  layer  of  the  choroid.     They  may  be  divided 

into  great  and  small,  the  latter  occupying  the  intervals  between  

the  former.  They  all  increase  in  size  (from  b  to  a,  fig.  243)  as  Pcterior  or  imemJ  view. 
they  approach  the  outer  border  of  the  iris,  behind  which  they  are  prolonged  without  adhe- 
ring to  it,  and  are  then  bent  forward  upon  themselves,  to  be  attached  to  that  border.  These 
ciliary  processes,  the  sides  of  which  are  turned  towards  each  other,  have,  therefore,  a 
posterior  adherent  or  choroid  portion  (b),  and  an  anterior  free  or  iridian  portion  (a).  The 
free  portion  (c  e,  fi^.  241 ;  a,  fig.  244)  floats  among  the  humours  of  the  eye  like  a  fringe  ; 
,the  slightest  agitation  of  the  vessel  or  of  the  liquid  in  which  the 
ciliary  processes  are  contained  is  immediately  communicated  to 
this  free  portion  of  the  corona  ciliaris. 

The  ciliary  body  or  disc,  which  is  formed  by  the  union  of  all  the 
ciliary  processes  or  rays,  is  in  relation  behind  with  the  vitreous 
body  {v  in  the  centre,  ^^.  241),  and  advances  (e,fig.  241  ;  a,  fig. 
244,  in  which  the  iris  is  removed)  over  the  circumference  of  the 
crystalline  lens.  It  is  not  simply  in  contact  with  the  vitreous  body, 
but  is  rather  firmly  adherent  to  it ;  and  we  shall  afterward  see  that 
they  are  dovetailed  together,  that  is,  the  ciliary  processes  of  the 
vitreous  body  are  fitted  into  the  intervals  between  the  ciliary  pro-  Anterior  view-im  removed 
cesses  of  the  choroid,  and  vice  versa. 

If  the  thick  layer  of  pigment  with  which  they  are  covered  be  removed,  the  ciliary 
processes  of  the  choroid,  when  examined  through  a  lens  under  water,  have  a  white  colour. 
In  their  substance  are  seen  irregular  cells  which  are  filled  with  the  brown  pigment,  and 
which  give  them  a  spongy,  and,  as  it  were,  jagged  appearance.  They  are  evidently  con- 
tinuous with  the  choroid,  which  irxmiediately  around  them  presents  a  zone  of  a  whiter 
colour  than  the  rest  of  the  inner  surface  of  that  membrane. 

Structure  of  the  Choroid  Coat  and  its  Ciliary  Processes. — The  structure  of  these  parts  is 
essenticdly  vascular.  Fine  injections  thrown  into  the  carotid  artery  and  internal  jugular 
vein,  in  young  subjects,  fill  a  beautiful  network  of  vessels  in  this  membrane.  The  vor- 
ticose arrangement  {v,  fig.  244)  of  some  of  these  vessels  is  then  clearly  displayed ;  and, 
indeed,  this  is  very  well  indicated,  without  the  aid  of  an  injection,  by  the  striae  already 
described  as  visible  upon  the  surfaces  of  the  choroid.  The  short  ciliary  arteries  belong 
exclusively  to  the  choroid  coat.  From  a  great  number  of  experiments  made  by  M.  Ribes, 
it  would  appear  that  injections  pushed  into  the  arteries  do  not  enter  the  vdli  and  fringes 
of  the  ciliary  body,  but  that  their  vessels  may  be  filled  from  the  veins  ;  so  that,  accord- 
ing to  this,  the  structure  of  the  free  and  fringed  portion  of  the  ciliary  processes  is  alto 
gether  venous,  like  the  cavernous  or  erectile  tissues.* 

From  the  different  appearance  of  the  external  and  internal  surfaces  of  the  choroid, 
anatomists  have  regarded  this  coat  as  being  composed  of  two  layers,  of  which  the  in- 
ternal is  called  the  membrana  Ruyschiana,  after  Ruysch,  who  has  given  the  best  descrip- 
tion of  it.  According  to  one  view,  which  is  not  altogether  unsupported,  the  internal 
layer  alone  concurs  in  the  formation  of  the  ciliary  processes,  while  the  external  layer 
corresponds  to  the  ciliary  ring. 

The  Iris. 

The  iris  {i,  figs.  242,  243),  so  called  on  account  of  the  varied  colours  which  it  presents, 
is  a  membranous  vertical  septum,  perforated  in  the  centre,  like  the  diaphragm  of  an  op- 
tical instrument.  By  means  of  this  septum  (i,  fig.  241),  the  space  {p)  between  the  cornea 
(m)  and  the  crystalline  lens  (f)  is  divided  into  two  parts  or  chambers,  an  anterior  and  a 
posterior.  The  iris  is  circular,  and  perforated  in  its  centre  by  an  opening  which  consti- 
tutes the  pupil  {p,  fig.  242),  vulgarly,  the  apple  of  the  eye,  and  which  is  surrounded  by 
the  lesser  or  inner  border  of  the  iris ;  the  pupil  is  circular  in  the  human  subject,  and  oblong, 

*  [In  successful  injections,  arterial  as  well  as  venous  ramifications  are  demonstrated  in  the  ciliary  processes. 1 

40 


658  NEUROLOGY. 

either  transversely  or  vertically,  in  the  lower  animals  ;  the  number  of  luminous  rays  suf- 
fered to  impinge  upon  the  retina  are  regulated  by  variations  in  the  size  of  this  opening. 
We  constantly  find  in  several  kinds  of  animals,  and  occasionally  in  the  human  subject, 
small  fringes  attached  to  the  lesser  border  of  the  iris,  which  float  in  the  aqueous  humour. 

The  outer  or  greater  border  of  the  iris  is,  as  it  were,  fitted  in  between  the  ciliary  liga- 
ment, which  projects  beyond  it  slightly  in  front,  and  the  ciliary  processes,  which  encroach 
upon  it  behind  {see  Jig.  241).  The  manner  in  which  it  adheres  to  these  parts  is  not  well 
understood.  There  is  a  true  continuity  of  tissue,  and  yet  they  may  be  separated  by  a 
slight  degree  of  force ;  on  this  is  founded  the  operation  for  artificial  pupil  by  detaching  the 
iris.     The  outer  border  of  the  iris  is  not  continuous  with  the  circumference  of  the  cornea. 

The  anterior  surface  of  the  iris  {i,  fig.  242),  with  its  different  shades  of  colour,  is  the 
part  which  is  seen  through  the  transparent  cornea ;  it  is  plane,  not  convex.  The  inter- 
val between  it  and  the  cornea  constitutes  the  anterior  chamber  of  the  eye  {fig.  241). 
The  form  and  size  of  this  interval  can  be  correctly  estimated  in  a  frozen  eye  ;  it  is  filled 
with  the  aqueous  humour ;  its  longest  diameter  from  before  backward  is  about  one  line. 

When  examined  with  a  lens,  the  anterior  surface  of  the  iris  has  a  flocculent  appear- 
ance, more  distinct  than,  but  similar  to,  that  of  the  external  surface  of  the  choroid.  It 
appears  as  if  it  were  fissured  here  and  there,  and  in  the  human  subject  presents  some 
very  well-marked  radiated  bands.  When  the  pupil  is  contracted  these  radiated  banda 
are  straight,  but  during  its  dilatation  they  become  flexuons.  They  appear  to  interlace, 
and  thus  to  become  blended  with  each  other  near  the  pupil.  It  is  generally  admitted 
that  the  membrane  of  the  aqueous  humour  covers  the  anterior  surface  of  the  iris  ;  but  it 
cannot  be  demonstrated  in  that  situation.  The  colour  of  this  surface  differs  in  different 
individuals,  and  it  has  generally  some  relation  to  that  of  the  hair  ;  upon  these  differences 
depend  the  colour  of  the  eyes,  whether  blue,  black,  gray,  &c.  Whatever  may  be  the 
colour  of  the  iris,  two  shades  of  different  intensity  may  be  distinguished  in  it,  and  occa- 
sion the  appearance  of  two  concentric  coloured  zones  in  this  membrane  ;  the  smaller  and 
deeper-coloured  zone  is  situated  near  the  pupil ;  the  larger  and  lighter-coloured  one  in- 
cludes the  two  outer  thirds  of  the  membrane.  It  is  not  always  easy  to  distinguish  these 
two  zones. 

The  posterior  surface  {i,  fig.  243)  of  the  iris  corresponds  to  the  crystalline  lens,  from 
which  it  is  separated  by  an  interval  filled  with  the  aqueous  humour,  and  called  the  pos- 
terior chamber  of  the  eye  {fig.  241). 

The  two  chambers  of  the  eye,  therefore,  communicate  at  the  pupil  {p). 

The  posterior  surface  of  the  iris  is  covered  by  a  thick  layer  of  pigment,  which  is  con- 
tinuous with  the  pigment  of  the  choroid ;  near  its  outer  border  it  is  also  overlaid  by  the 
free  or  iridian  portion  (c  e)  of  the  ciliary  processes  of  the  choroid,  which  can  be  easily 
turned  back  so  as  to  expose  the  entire  posterior  surface.  It  presents  extremely  well- 
marked  radiated  bands,  which  can  be  well  seen,  even  before  the  choroid  pigment  is  re- 
moved. 

The  aspect  of  the  posterior  surface  of  the  iris  differs  essentially  from  that  of  the  an- 
terior surface  ;  it  is  white  and  smooth,  and  resembles  in  many  respects  the  internal  sur- 
face of  the  choroid.  Some  anatomists  are  of  opinion  that  the  posterior  surface  of  the 
iris  is  covered  by  the  membrane  of  the  aqueous  humour.  If  such  be  the  case,  it  is  difll- 
cult  to  comprehend  how  that  membrane  is  arranged  with  reference  to  the  pigment. 

Structure. — The  iris  is  three  or  four  times  as  thick  as  the  choroid  ;  it  diminishes  in 
thickness  from  its  outer  to  its  inner  border.  Its  real  structure  is  but  little  understood. 
The  old  opinion  of  its  muscularity,  which  was  refuted  by  Weitbrecht  and  Demours,  has 
been  revived  by  M.  Maunoir,  who  admits  two  sets  of  muscular  fibres,  viz.,  radiated  fibres, 
which  correspond  to  the  external  coloured  ring,  and  circular  fibres,  which  correspond  to 
the  internal  coloured  ring,  and  form  a  sort  of  sphincter  around  the  pupil ;  but  no  circular 
fibres  can  be  distinguished  around  the  pupil.  An  appearance  as  if  such  were  the  case, 
is  occasioned  by  a  peculiar  arrangement  of  the  radiated  fibres,  which  seem  to  bifurcate 
opposite  the  internal  coloured  ring,  to  interlace  with  each  other,  and  then  terminate  ab- 
ruptly around  the  pupil ;  so  that  the  inner  border  of  the  iris,  or  the  pupil,  appears  to  be 
formed  by  the  blunt  extremities  of  these  radiated  fibres. 

In  the  ox  and  the  sheep,  the  iris  has  two  very  distinct  sets  of  fibres  :  an  anterior  and 
circular  layer,  which  occupies  the  whole  of  the  anterior  surface  ;  and  a  posterior  and 
radiated  set  of  fibres,  which  converge  from  the  outer  to  the  inner  border.  The  anterior 
set  of  fibres  does  not  exist  in  the  human  subject. 

Another  and  much  more  plausible  opinion  regarding  the  structure  of  the  iris  is,  that  it 
consists  of  a  vascular  or  erectile  texture.* 

If  we  examine  an  oblique  section  of  the  iris  under  a  lens,  we  find,  indeed,  that  it  has 
an  areolar  spongy  structure ;  and  the  extreme  vascularity  of  this  part  also  supports  the 
same  view. 

*  A  case  is  related  of  a  young  man  who  could  produce  contraction  of  the  pupils  by  holding  his  breath. 

[The  muscularity  of  the  fibres  of  the  iris  i.s  now  established  beyond  a  doubt ;  the  fibres  of  the  iris  of  the  pig 
are  described  by  Schwann  as  being  very  minute,  cylindrical,  and  not  beaded  ;  thev  therefore  resemble  the 
muscular  fibres  of  organic  life.] 


THE    MEMBBANA    PUPILLARIS,  ETC.  659 

Arteries  of  the  Iris. — The  arteries  of  the  iris  are  principally  derived  from  the  two  long 
ciliary  arteries,  which  bifurcate  and  anastomose  after  they  have  reached  the  ciliary  liga- 
ment, and  form  a  vascular  circle,  which  gives  off  radiated  vessels  that  converge  from  the 
outer  border  of  the  iris  towards  the  pupil.  There  are  also  some  anastomotic  arches 
near  the  pupil. 

Veins  of  the  Iris. — The  veins  of  the  iris  are  much  more  numerous  than  the  arteries  ; 
they  terminate  in  the  venae  comites  of  the  long  ciliary  arteries,  and  in  the  vasa  vorticosa. 

Nerves. — The  nerves  of  the  iris,  or  ciliary  nerves  {a  a,  fig.  242),  are  very  large  ;  as  we 
have  stated,  they  gain  the  ciliary  circle,  and  then  pass  through  it  in  great  numbers,  to 
enter  the  iris,  and  be  distributed  in  its  substance.  Most  of  these  nerves  are  given  off 
from  the  ophthalmic  ganglion  :  some  of  them  are  derived  directly  from  the  nasal  nerve, 
which  is  a  branch  of  the  fifth  cranial  nerve. 

The  older  anatomists  distinguished  two  layers  in  the  iris :  one  anterior,  which  they  called 
the  membrane  of  the  iris  ;  the  other  posterior,  covered  with  pigment,  which  they  called 
membrana  uvea.  By  examining  an  oblique  section  of  the  iris  with  a  lens,  two  layers  may, 
in  fact,  be  seen,  separated  by  the  spongy  tissue  of  which  I  have  spoken 

The  Memhrana  Pupillaris. 

Dissection. — By  opening  the  eye  of  the  foetus  from  behind,  this  vascular  membrane 
may  be  easily  seen  through  the  vitreous  body  and  the  crystalline  lens. 

In  the  foetus,  the  opening  of  the  pupil  is  closed  by  a  membane,  called  the  membrana 
pupillaris,  which  was  discovered  and  very  well  described  by  Wachendorf,  but  more  per- 
fectly so  by  Haller  and  Soemmering,  and  recently  by  M.  Jules  Cioquet.  It  may  be  seen 
about  the  third  month  of  intra-uterine  life,  and  generally  disappears  towards  the  seventh 
month.  When  persistent,  it  may  occasion  congenital  blindness.  Wachendorf  and 
Soemmering  have  demonstrated  the  vessels  of  this  membrane,  which  are  continuous 
with  those  of  the  iris.  During  the  existence  of  the  membrana  pupillaris,  the  membrane 
of  the  aqueous  humour  forms  a  shut  sac.  From  the  researches  of  M.  Jules  Cioquet  con- 
cerning the  pupillary  membrane,  it  appears  that  it  consists  of  two  thin  layers,  between 
which  the  bloodvessels  are  arranged  in  loops ;  that  the  convexities  of  these  loops  are 
turned  towards  each  other,  but  that  the  loops  which  approach  each  other  from  opposite 
sides  do  not  anastomose  together ;  that  between  these  loops,  and  towards  the  centre  of 
the  pupil,  there  is  a  small  irregular  portion  of  the  membrane  which  is  destitute  of  ves- 
sels, and  is,  therefore,  weaker  than  any  other  part ;  that  the  formation  of  the  pupil  is 
effected  by  the  rupture  of  this  membrane,  and  that  this  rupture  is  occasioned  by  the  re- 
traction of  the  vascular  loops,  which  ultimately  occupy  the  lesser  border  of  the  iris. 

Uses  of  the  Iris. — The  iris  regulates  the  quantity  of  light  that  is  admitted  into  the  in- 
terior of  the  eye.  The  contraction  of  the  pupil  is  an  active  movement,  and  its  dilatation 
is  passive ;  facts  which  are  opposed  to  the  doctrine  of  its  muscularity,  but  support  the 
idea  of  its  being  a  vascular  and  erectile  structure. 

It  has  been  stated  that  the  movements  of  the  iris  are  intended  to  enable  us  to  judge 
of  the  distance  and  size  of  objects,  or,  rather,  to  enable  us  to  see  objects  at  different  dis- 
tances :  this  is  erroneous,  for  the  pupil  remains  of  the  same  size,  under  the  action  of  a 
similar  quantity  of  light,  whether  the  object  looked  at  be  near  or  distant.*  The  effect 
of  narcotics,  and  especially  of  belladonna,  either  applied  topically,  or  taken  internally,  in 
producing  dilatation  of  the  pupil,  is  one  of  the  most  curious  facts  concerning  the  iris. 
The  direct  action  of  the  rays  of  light  upon  the  iris  has  no  influence  upon  the  size  of  the 
pupil,  the  dimensions  of  which  are  altered  either  by  the  action  of  light  upon  the  retina, 
or  in  consequence  of  a  peculiar  condition  of  the  optic  nerve  of  the  brain 

The  Pigment  of  the  Eye. 

It  has  been  stated  that  the  external  surface  of  the  choroid  and  the  internal  surface  of 
the  sclerotic  are  coloured  by  a  very  thin  layer  of  pigment ;  and  also  that  the  internal  sur- 
face of  the  choroid  is  covered  with  a  thicker  layer,  which  is  itself  thickest  on  the  fore 
part  of  that  surface,  near  the  ciliary  body,  between  the  greater  ciliary  processes,  and  be- 
hind the  iris.  By  means  of  this  pigment  the  interior  of  the  eye  is  converted  into  a  true 
dark  chamber.  StUl,  it  may  be  asked  why  the  pigment  is  less  abundant  behind  than  in 
front. 

The  choroid  pigment  is  not  black,  but  of  a  very  dark-brown  colour,  like  bistre ;  in  this 
respect  resembhng  the  pigment  of  the  skin  of  the  negro ;  it  consists  of  molecules  or 
globules  insoluble  in  water. 

The  pigment  of  the  choroid  of  the  iris  is  wanting  in  albinoes.  as  well  as  the  cutaneous 
pigment.     Both  have  the  same  chemical  composition,  t 

*  [The  pupil  certainly  dilates  in  looking  at  distant  objects,  and  contracts  under  the  opposite  circumstances  ; 
but  it  is  by  no  means  certain  that  the  adjustment  of  the  eye  to  objects  at  different  distances  depends  on  these 
alterations  in  the  condition  of  the  iris.] 

t  [The  pigment  of  the  eye  consists  of  nucleated  cells  containing  the  pigment  granules  ;  on  the  inner  surface 
of  the  choroid  these  cells  are  flattened  and  hexagonal,  and  their  sides  fit  accurately  together,  so  as  to  present 
an  appearance  like  mosaic  work  ;  on  the  back  of  the  iris  the  cells  are  irregularly  rounded.  In  albinoes  the 
cells  contain  no  coloured  granules.] 


mi 


NEUROLOGY. 


In  some  animals  the  pigment  of  the  eye  has  a  metallic  lustre,  and  an  iridescent  aspect 
in  a  great  part  of  its  extent. 

The  Retina. 
The  retina  (r,figs.  241,  245),  counting  from  without  inward,  is  the  third  membrane  ol 
the  eye  ;  it  is  the  immediate  seat  of  vision,  and  is  an  essentially  nervous  membrane,  sit- 
uated within  the  choroid  and  the  sclerotic.  Its  external  surface  (jr,fi.g.  245)  corresponds 
to  the  choroid,  from  which  it  is  separated  by  the  pigment,  which,  in  eyes  that  have  un- 
dergone slight  decomposition,  forms  an  irregular  layer  upon  it,  like  a  web.  Dr.  Jacob 
(Philosoph.  Trans.,  1819)  has  described  a  serous  membrane  between  the  retina  and  the 
choroid,  in  the  cavity  of  which  a  dropsical  effusion  may  occur,  and  constitute  what  is 
called  ;)os<enor  staphyloma  of  the  eye.  M.  Weber  believes  that  this  membrane  is  prolonged 
forward  to  the  circumference  of  the  crystalline  lens,  and  is  then  reflected  over  the  pos- 
terior surface  of  the  iris,  where  it  becomes  continuous  with  the  membrane  of  the  aque- 
ous humour.     I  have  not  succeeded  in  demonstrating  the  membrane  of  Jacob.* 

The  internal  surface  (r,  fig.  246)  of  the  retina  is  applied  to  the  vitreous  body,  but  does 
not  adhere  in  the  slightest  degree  to  it. 

The  point  at  which  the  retina  terminates  in  front  is  still  regarded  by  most  anatomists 
as  undetermined.  Several,  with  the  older  authors,  describe  it  as  extending  to  the  cir- 
cumference of  the  crystalline  lens.  Some  entertain  a  modification  of  this  opinion,  be- 
lieving that  an  extremely  thin  membrane  is  given  off  from  the  rim  {r'r",  fig.  241)  in 
which  the  retina  seems  to  terminate,  and  that  this  membrane  advances  upon  the  inner 
surface  of  the  ciliary  body  to  the  front  of  the  capsule  of  the  crystalline  lens,  to  which  it 
is  attached.  M.  Duges,  in  an  excellent  work  upon  the  comparative  anatomy  of  the  or- 
gan of  vision,  expresses  a  somewhat  different  opinion  :  according  to  his  view,  the  retina 
having  reached  the  ciliary  processes,  divides  into  numerous  tongues,  each  of  which  passes 
between  two  of  the  ciliary  processes,  and  terminates  by  expanding  upon  the  circumfer- 
ence of  the  crystalline  lens.  A  careful  examination  has  proved  to  me  distinctly  that  the 
retina  terminates  by  a  defined  edge  (margo  dentatus,  r'r',fig.  241  ;  m,fig.  245)  at  the 
Fie  245  posterior  extremities  of  the  ciliary  processes  of  the  vitreous 

body  (a),  to  which  processes  it  adheres  rather  firmly,  though  it 
can  be  sometimes  separated  from  them  Avithout  laceration. 

Is  the  retina  an  expansion  of  the  medullary  part  of  the  optic 
nerve,  or  is  it  a  special  organ  continuous  with  that  nerve  ! 
Although  the  former  of  these  opinions  appears  more  probable 
than  the  latter,  still  it  is  liable  to  objections.  The  optic  nerve 
is  constructed  in  a  particular  manner  as  it  passes  through  the 
sclerotic,  and  the  corresponding  nervous  substance  is  so  ar- 
ranged that  pressure  upon  the  nerve  does  not  force  the  ner- 
vous substance  into  the  interior  of  the  eye,  though  pressure 
upon  every  other  part  of  the  nerve  causes  a  white  pulpy  matter  to  exude  from  its  divided 
surface. 

The  retina  is  semi-transparent,  like  a  thin  layer  of  opal :  it  scarcely  holds  together, 
and  can  be  torn  with  the  greatest  facility.  It  does  not  appear  to  me  to  be  thicker  be- 
hind than  in  front. 

The  radiated  lines  stated  by  several  of  the  older  anatomists,  and  also  byM.  Duges,  to 
exist  in  the  retina,  can  only  be  distinguished  behind  at  the  entrance  of  the  optic  nerve. 
Tliis  radiated  character  was  evident  in  the  eye  of  an  ox  which  I  recently  examined.  The 
optic  nerve  divided  into  three  thick  diverging  bundles,  which  expanded  into  a  layer  ;  but 
this  filamentous  arrangement  was  soon  succeeded  by  what  appeared,  at  least,  to  be  a 
pulpy  structure. 

Two  layers  are  described  in  the  retina :  an  external,  which  is  pulpy  and  nervous ;  and 
an  internal,  which  is  vascular,  and  is  formed  by  the  ramifications  ol^  the  arteria  centralis 
retinae ;  but  this  subdivision  of  the  retina  is  purely  fictitious.  Soemmering  has  given 
a  good  representation  of  the  vascular  network,  which  seems  in  some  manner  to  support 
the  nervous  substance. 

The  Foramen  Centrale,  the  Fold,  and  the  Limbus  Luteua  vf  the  Retina^ — Soemmering 
was  the  first  to  describe  in  the  retina  a  foramen  {foramen  centrale),  which  had  escaped 
the  researches  of  Ruysch,  Zinn,  and  Haller,  doubtless  because  it  is  concealed  by  the  folds 
formed  by  the  retina  at  this  point. 

It  is  doubtful  whether  these  folds  of  the  retina  result  from  the  collapsed  condition  of 
the  eyeball,  which  necessarily  follows  the  dissection  required  for  the  examination  of  its 
interior ;  or  whether  they  are  really  part  of  its  structure,  and  should  be  regarded  as  the 
vestige  of  the  singular  folds  existing  in  different  kinds  of  animals,  and  especially  in  birds, 
the  visual  powers  of  which  are  thereby  greatly  increased.  However  this  may  be,  the 
foramen,  which  is  always  situated  to  the  outer  side  of  the  entrance  {b,  fig.  246)  of  the 

*  [If  the  posterior  part  of  the  sclerotic  and  choroid  be  carefully  removed  from  a  fresh  eye  (leaving  the  optic 
nerve  untouched),  and  the  eye  be  then  macerated  a  few  hours  in  water,  portions  of  Jacob's  membrane  will 
either  senarate,  or  they  ca"n  easily  be  separated  from  the  outer  surface  of  tlie  retina.] 


THE    VITREOUS   BODY. 


66] 


optic  nerve,  is  surrounded  with  a  zone  of  a  canary-yellow  colour :  this  is  the  limhus  lu- 
teus  foraminis  centralis  {Sammering),  or  the  yellow  spot  of  Sam-  „. 

mering  (a).  ^' 

The  foramen  centrale  and  the  limbus  luteus  exist  in  man  and  the 
quadrumana  only ;  that  is  to  say,  in  those  cases  only  in  which  the 
visual  axes  of  the  two  eyes  are  parallel  to  each  other,  as  in  man. 

I  have  not  found  that  the  yellow  spot  corresponds  to  the  thick- 
est part  of  the  retina. 

It  should,  moreover,  be  observed,  that  the  foramen  centrale,  not 
the  entrance  of  the  optic  nerve,  corresponds  to  the  antero-posterior 
axis  of  the  globe  of  the  eye,  and  is  the  true  centre  of  the  retina. 

The  uses  of  the  central  foramen  and  the  yellow  spot  are  not 
known. 

The  yellow  spot  does  not  exist  in  the  foetus.* 

The  Humours  of  the  Eye. 
The  media  through  which  the  light  passes  in  the  eye,  besides  the  transparent  cornea 
already  described,  are  the  vitreous  body,  the  crystalline  lens,  and  the  aqueous  humour. 

The  Vitreous  or  Hyaloid  Body. 

The  vitreous  or  hyaloid  body  {v,Jigs.  247,  248)  (from  va?.oc,  glass),  so  called  from  its  re- 
semblance to  glass,  is  an  imperfectly  spheroidal,  and  quite  transparent  mass,  which  oc- 
cupies the  posterior  three  fourths  (v,Jig.  241)  of  the  globe  of  the  eye ;  it  is  covered  im- 
mediately by  the  retina  {v,  fig.  245),  which  is  simply  in  contact  with  it,  and  indirectly  by 
the  other  coats  of  the  back  part  of  the  eye,  which  are  accurately  moulded  upon  it.  It  pre- 
sents a  slight  depression  in  front,  for  the  reception  of  the  posterior  surface  of  the  crys- 
talline lens  (/).  The  vitreous  body  and  the  crystalline  lens  together  very  nearly  resem- 
ble in  form  the  entire  globe  of  the  eye,  the  projection  of  the  crystalline  lens  representing 
the  prominence  of  the  cornea  (compare  figs.  241  and  245). 

The  vitreous  body  is  composed  of  a  liquid,  named  the  vitreous  humour,  i  and  of  the  hy- 
aloid membrane. 

The  hyaloid  membrane  {h,fig.  241),  which  was  first  discovered  by  Fallopius,  can  be 
easily  demonstrated  by  puncturing  the  vitreous  body,  and  allowing  the  vitreous  humour 
to  escape.  If  it  be  then  dipped  in  diluted  nitric  acid,  the  membrane  will  become  opaque, 
and  easily  distinguishable.  This  membrane  not  only  forms  a  general  investment  or  cap- 
sule for  the  vitreous  body,  but  gives  off  lamellar  prolongations  from  its  internal  surface, 
which  separate  the  vitreous  humour  into  an  irregular  number  of  compartments,  or  cells. 
The  existence  of  these  cells  can  be  easily  proved  by  moving  the  vitreous  body  between 
the  fingers ;  and  if  this  body  be  frozen,  their  shape  is  shown  by  that  of  the  masses  of  ice 
which  may  be  taken  from  them. 

It  is  generally  admitted  that  all  these  cells  communicate  with  each  other ;  because, 
when  one  of  them  only  is  punctured,  all  the  vitreous  humour  will  gradually  escape. 
Still,  I  have  several  times  observed  that  the  eye  did  not  collapse  when  a  part  of  the  vit- 
reous body  had  escaped  in  the  operation  for  extracting  a  cataract ;  this,  however,  might 
have  depended  upon  any  farther  escape  being  opposed  by  the  approximation  of  the  lips 
of  the  incision. 

The  manner  in  which  the  hyaloid  membrane  is  arranged  with  reference  to  the  crys- 
talline lens  is  still  a  disputed  point.  It  is  generally  admitted  that,  about  a  line  from  the 
margin  of  the  crystalline  lens,  the  hyaloid  membrane  divides  into  two  layers,  one  of 
which  passes  behind  {h,fig.  241)  and  the  other  in  front  of  the 
lens.  The  three-sided  interval  (s  s)  which  exists  all  round  the 
crystalline  lens,  and  which  has  been  described  by  Fran9ois  Petit, 
under  the  name  of  canal  godronne,  is  formed  between  these  two 
layers  and  the  lens.  This  circular  canal,  or  canal  of  Petit,  can 
be  very  easily  shown  by  blowing  air  into  it  (as  in  p,fig.  247) ; 
it  is  then  seen  to  be  constricted  at  intervals,  as  if  by  small  folds 
or  bands,  so  that  it  presents  a  knotted  or  plaited  appearance. 
Other  anatomists,  on  the  contrary,  state  that  the  hyaloid  mem- 
brane does  not  split  into  two  layers,  but  passes  altogether  behind 
the  crystaUine  lens,  in  order  to  cover  the  front  of  the  vitreous  body. 


Fi>.  247. 


It  is  certain  that 


*  [From  recent  researches,  especially  those  of  Valentin  and  Hanover,  the  following  appears  to  be  the  mi- 
nute structure  of  the  retina:  1.  The  membrane  of  Jacob  consists  of  minute  cylindrical  or  prismatic  bodies, 
placed  closely  together,  and  perpendicularly  to  the  surface  of  the  membrane  ;  among  these  are  somewhat  lar- 
ger bodies,  "coni  gemini,"  which  might  be  compared  in  shape  to  two  cylinders  applied  to  each  other  length- 
wise. Both  kinds  of  bodies  are  attached  by  one  extremity  to  the  inner  surface  of  the  choroid,  being  received 
into  exceedingly  minute  sheaths,  which  rise  from  the  surface  of  the  pigment  cells.  2.  The  filaments  of  the 
optic  nerve  spread  out  on  the  inner  surface  of  this  structure,  and,  according  to  Valentin,  have  a  plexiform  ar- 
rangement, but  their  mode  of  termination  seems  doubtful.  This  nen-ous  expansion  is  covered  on  its  outer  and 
also  on  its  inner  surface  by  a  layer  of  ganglionic  globules.] 

t  [The  vitreous  humour,  according  to  Ilerzelius,  contains  98'4  per  cent,  of  water ;  its  solid  matter  consists 
of  albumen,  extractive  matter,  and  chloride  of  sodium.] 


662  NEUROLOGY. 

a  circular  layer,  having  the  form  of  a  radiated  crown,  is  given  off  from  the  anterior  part 
of  the  hyaloid  membrane  ;  this  circular  radiated  disk  w^as  described  by  Petit  and  Cam- 
per, but  it  is  called  the  corona  ciliaris,  or  the  zonula  Zinni :  it  corresponds  accurately  to 
the  ciliary  processes  and  ciliary  body  of  the  choroid  coat. 

The  ciliary  zone  of  Zinn  (a,  Jig.  245,  b,  figs.  247,  248),  or  the  ciliary  processes  of  the  vit- 
Fig.m.  reous  body,  can  be  seen  through  that  transparent  body  {d,fig.  241) 

when  the  several  coats  are  removed  from  the  back  part  of  the 
globe  of  the  eye  :  it  is  completely  exposed  to  view  when  the  cho- 
roid coat  and  the  iris  are  separated  from  the  vitreous  body  {fig. 
248).  It  is  this  structure  which  constitutes  the  beautiful  radiated 
crown  situated  in  front  of  the  vitreous  body  around  the  crystalline 
lens,  and  which  extends  considerably  beyond  the  ciliary  body  of 
the  choroid ;  it  consists  of  alternate  black  and  transparent  rays, 
and  is  generally  regarded  as  a  reverse  impression  of  the  ciliary 
processes  of  the  choroid.  The  ciliary  processes  of  the  vitreous 
body  correspond  to  the  black  lines,  and  the  intervals  between  the 
processes  to  the  transparent  rays. 

The  ciliary  processes  of  the  vitreous  body  are  not  so  thick  as  those  of  the  choroid ; 
but  the  folds  of  which  they  consist  commence  farther  back  than  the  ciliary  processes  of 
the  choroid,  so  that  the  radiated  disc  formed  by  them  is  larger  than  that  formed  by  the 
processes  of  the  choroid.  These  folds  of  the  vitreous  body  have  the  same  spongy  and 
jagged  appearance  as  those  of  the  choroid :  they  have  no  free  portion,  or,  rather,  that 
part  of  the  zone  of  Zinn  (a,  fig.  248)  which  corresponds  to  the  free  portion  of  the  ciliary 
processes  of  the  choroid  is  applied  to  the  crystalline  lens. 

The  cihary  processes  of  the  choroid  and  those  of  the  vitreous  body  are  so  arranged 
that  those  of  the  one  are  received  in  the  intervals  between  those  of  the  other.  It  ap- 
pears to  me  difficult  to  determine  whether  they  are  simply  applied  to  each  other,  or 
whether  their  structure  is  continuous.  However,  on  examining  these  parts  through  a 
lens  while  they  are  being  separated,  it  has  appeared  to  me  that  a  sort  of  cellular  struc- 
ture was  lacerated,  and  that  the  black  pigment,  which  had  been  hitherto  confined,  es- 
caped together  with  a  little  fluid.  M.  Ribes  believes  that,  during  this  separation,  some 
shreds  of  the  hyaloid  membrane  are  drawn  away  with  the  ciliary  processes  of  the  choroid. 
The  inner  border  (a)  of  the  cihary  zone  of  Zinn  is  in  contact  with  the  margin  of  the 
crystalline  lens  (/),  and  adheres  rather  firmly  to  it.  Around  the  outer  border,  which  ex- 
tends beyond  the  ciliary  body  of  the  choroid,  are  found  the  origins  of  certain  radiated 
folds  (i),  which  form,  as  it  were,  the  commencement  of  the  ciliary  processes.  This  bor- 
der adheres  to  the  anterior  margin  of  the  retina  {m,  fig.  245),  which  appears  to  me  to  be 
thickened  and  shghtly  uneven  in  this  situation,  and  not  to  be  continuous  with  the  hya- 
loid membrane. 

From  what  has  been  stated,  it  follows  that  the  canal  of  Petit  is  formed  between  the 
hyaloid  membrane  and  the  zone  of  Zinn,  and  that  the  crystalline  lens  is  fixed  by  this 
zone  to  the  anterior  margin  of  the  vitreous  body  ;  that  the  anterior  surface  of  the  crys- 
talline lens  is  not  covered  by  a  prolongation  of  the  hyaloid  membrane,  besides  its  own 
capsule  ;  and  that  the  retina  does  not  reach  as  far  as  the  margin  of  the  crystalline  lens. 
M.  Jules  Cloquet  has  described,  under  the  name  of  the  hyaloid  canal,  a  cylindrical  pas- 
sage, which  is  formed  by  the  reflection  of  the  hyaloid  membrane  into  the  interior  of  the 
vitreous  body  around  the  nutritious  artery  of  the  lens,  and  which,  like  that  artery,  trav- 
erses the  vitreous  body  from  behind  forward.  I  have  never  been  able  to  see  this  canal. 
No  vessels  have  been  demonstrated  in  the  hyaloid  membrane  ;  it  does  not  receive 
any  from  the  retina,  and  yet  we  cannot  doubt  that  it  is  provided  with  them.  Although 
the  structure  of  the  ciliary  processes  of  the  vitreous  body  is  little  known,  yet,  as  it  is 
probable  that  it  is  similar  to  that  of  the  ciliary  processes  of  the  choroid,  and,  therefore, 
essentially  vascular,  it  may  be,  as  stated  by  M.  Ribes,  that  the  materials  for  the  forma- 
tion and  nutrition  of  the  lens  and  of  the  ciliary  processes  of  the  vitreous  body  are  con- 
veyed to  both  of  these  parts  through  the  vascular  ciliary  processes  of  the  choroid. 

The  Crystalline  Lens  and  its  Capsule. 

The  crystalline  lens  {I,  figs.  241,  244,  245,  248)  is  a  transparent  body,  having  the  form 
of  a  lens,  as  its  name  implies  ;  it  is  situated  at  the  junction  of  the  posterior  three  fourths 
with  the  anterior  fourth  of  the  globe  of  the  eye,  and  is  placed  between  the  vitreous  body, 
which  is  behind,  and  the  aqueous  humour,  which  is  in  front  {see  fig.  241). 

Its  axis  corresponds  to  the  centre  of  the  pupil. 

It  is  shaped  like  a  double  convex  lens,  the  posterior  surface  of  which  is  more  convex 
than  the  anterior.  From  some  very  exact  and  minute  investigations  which  have  been 
made  upon  this  point  by  Fran5ois  Petit  and  others,  it  appears  that  both  the  relative  and 
the  absolute  convexity  of  the  two  surfaces  of  the  crystalline  lens  are  subject  to  great 
varieties  in  different  individuals ;  that,  in  general,  the  posterior  convexity  forms  part  of 
a  circle  from  four  to  five  lines  in  diameter,  while  the  anterior  forms  part  of  one  from  six 
to  nine  lines  in  diameter.    In  some  subjects  the  degree  of  curvature  of  the  two  surfaces 


THE   CRYSTALLINE   LENS   AND   ITS   CAPSULE.  668" 

of  the  crystaDine  lens  is  almost  equal.    In  the  foetus  the  crystalline  lens  approaches  the 
spheroidal  form,  which  is  that  which  it  has  in  fishes. 

The  anterior  surface  of  the  crystalline  lens  corresponds  to 'the  iris,  from  which  it  is 
separated  by  the  aqueous  humour.  It  has  been  incorrectly  stated  by  Winslow  that  the 
crystalline  lens  pushes  the  iris  forward :  there  is  a  space  between  the  crystalline  lens 
and  the  iris  which  constitutes  the  posterior  chamber  of  the  eye.  The  anterior  surface 
of  the  lens  may  be  seen  through  the  pupil,  so  that  slight  shades  of  difference  in  the  col- 
our of  the  lens  may  be  detected.  When  the  pupil  is  very  much  dilated,  the  anterior  sur- 
face of  the  lens  is  entirely  exposed. 

Its  posterior  surface  is  in  relation  with  the  vitreous  body,  which  is  depressed  so  as  to 
receive  it.  This  surface  does  not  adhere  to  the  hyaloid  membrane.  When  dissecting 
a  subject  of  twenty-seven  years  of  age  who  had  suffered  with  hydrophthalmia  in  both 
eyes,  M.  Ribes  found  about  six  grains  of  a  limpid  fluid  between  the  hyaloid  membrane 
and  the  crystalline  lens  ;  so  that  the  space  occupied  by  tliis  fluid  might  have  been  taken 
for  a  third  chamber. 

The  margin  of  the  lens  {I,  fig.  248)  is  set  (like  the  stone  of  a  brooch)  in  the  ciliary  pro- 
cesses (a)  of  the  vitreous  body,  which  cover  and  adhere  to  the  fore  part  of  that  margin, 
so  that  the  lens  is  kept  firmly  in  its  place.  Its  margin  is  surrounded  by  the  canal  of 
Petit  {fig.  247). 

The  crystalhne  lens  presents  different  shades  of  colour  at  different  periods  of  life.  It 
is  reddish  in  the  foetus,  but  is  perfectly  transparent  after  birth  ;  in  the  adult,  it  becomes 
slightly  opaline  at  the  centre  ;  in  the  aged,  it  acquires  a  yellowish  opacity,  which  ap- 
proaches somewhat  to  the  colour  of  amber  or  topaz.  Morbid  opacity  of  the  lens  consti- 
tutes lenticular  cataract. 

The  crystalline  lens  consists  of  a  capsule,  and  of  a  proper  substance  enclosed  within  it. 

The  Substance  of  the  Crystalline  Lens. — When  stripped  of  its  capsule,  the  crystalhne 
lens  is  found  to  have  three  degrees  of  consistence,  at  different  parts :  thus,  at  its  sur- 
face, it  is  almost  of  a  liquid  softness  ;  below  this,  it  is  soft  and  gelatinous,  and  may  be 
crushed  by  the  finger — this  is  the  cortical  layer ;  and,  lastly,  it  is  hard  in  the  centre,  which 
is  called  the  nucleus,  and  closely  resembles  a  mass  of  gum-arabic.  The  most  superficial 
and  fluid  layers  constitute  the  liquor  Morgagni. 

The  substance  of  the  crystalline  lens  consists  of  concentric  layers  {b  c,  Jig.  249),  which 
can  be  very  easily  demonstrated,  even 
without  any  previous  preparation,  but 
are  rendered  most  distinct  by  boiling, 
or  immersion  in  a  diluted  acid.  The 
crystalline  lens  then  separates  into  su- 
perimposed laminae  or  scales,  like  the 
bulb  of  the  onion. 

The  different  degrees  of  consistence 
observed  in  the  substance  of  the  lens 
do  not  depend  upon  differences  in  na- 
ture, but  upon  mere  modifications.  When  hardened  by  an  acid,  the  structure  of  the  lens 
is  exactly  the  same  throughout :  even  the  liquor  Morgagni  appears  to  become  laminated. 

Each  of  these  concentric  lamina;  is  itself  composed  of  radiated  fibres  (a.  Jig.  249), 
which  can  be  readily  seen  without  dissection,  by  placing  one  of  them  upon  a  black  sur- 
face, and  examining  it  through  a  lens,  or  even  by  a  strong  Ught. 

Lastly,  the  crystalline  lens,  when  boiled,  or  submitted  to  the  action  of  an  acid,  splits 
into  three,  four,  or  even  a  greater  number  of  triangular  segments  (ab),  all  of  which  unite 
by  their  summits  at  the  centre  of  the  lens,  so  that  its  anterior  and  posterior  surfaces 
have  a  stellate  appearance.*  Pathologists  have  successfully  applied  this  anatomical 
fact  to  the  explanation  of  the  stellate  forms  of  cataract,  in  which  the  opacity  branches 
out  in  three  or  more  directions. 

What  is  the  nature  of  the  crystalline  lens  1  Is  it  the  product  of  a  secretion  1  or  is  it 
an  organized  structure  1  M.  Duges  has  recently  supported  by  his  authority  and  by  ad- 
ditional facts  the  opinion  of  Dr.  Young,  who  believed  that  the  crystalline  lens  is  not  only 
an  active  organized  structure,  supplied  with  vessels  and  veins,  but  that  it  is  even  mus- 
cular and  possessed  of  contractility,  so  as  to  be  able  of  itself  to  increase  or  diminish  its 
curvatures  and  its  density,  thus  endowing  the  eye  with  the  power  of  adjusting  itself  to 
the  different  distances  %f  the  objects  to  be  seen.  The  substance  of  the  lamina;  of  the 
crystalline  lens  has,  indeed,  a  linear  structure  ;  but  it  does  not  at  all  resemble  muscular 
tissue,  either  in  its  consistence  or  in  its  regularly  stratified  character.  I  conceive, 
therefore,  that  I  am  warranted  in  regarding  the  superimposed  layers  of  the  crystalline 
lens  as  the  solidified  product  of  a  secretion  formed  by  its  capsule,  t 

*  See  note,  infrd. 

t  [The  lines  indicating-  the  divisions  between  the  triangular  segments  of  the  lens  (a,  Jig-  249)  are  called  sep- 
ta; the  septa  of  the  anterior  surface  are  placed  opposite  the  intervals  between  the  septa  of  the  posterior  sur- 
face. The  fibres  of  which  the  laminie  are  composed  have  a  linear  arrangement,  and,  as  discovered  by  Sir  D. 
Brewster,  are  fitted  into  each  other  by  indented  margins  {Jig.  250).  Schwann  has  shown  that  those  fibres 
are  developed  from  rounded,  nucleated  cells,  which  become  elongated  into  fibres,  the  margins  of  which  sub- 


The  capsule  of  the  crystalline  lens  (jt,fig-  241)  is  accurately  fitted  to  the  lens  itself;  iff 
the  healthy  state  it  is  transparent,  but  may  become  opaque,  and  thus  constitute  a  mem- 
branous or  capsular  cataract. 

Its  external  surface  is  free  in  front,  where  it  is  bathed  by  the  aqueous  humour  :  it  is 
merely  in  contact  with  the  hyaloid  membrane  behind,  but  its  circumference  adheres  in- 
timately to  that  membrane,  or,  rather,  to  the  ciliary  zone  of  Zinn. 

Its  internal  surface  does  not  appear  in  the  slightest  degree  adherent  to  the  lens.  If 
an  incision  be  made  into  this  capsule  in  the  living  subject,  the  lens  is  forced  out  merely 
by  the  tonicity  of  the  coats  of  the  eye.  The  anterior  segment  of  the  capsule  is  twice  as 
thick  as  the  posterior :  it  might  be  compared  to  a  layer  of  the  cornea,* 

It  receives  bloodvessels  derived  from  the  arteria  centralis  retinae. t  These  vessels, 
according  to  Meckel,  are  distributed  only  upon  the  posterior  half  of  the  capsule  ;  those 
which  belong  to  the  anterior  half  arise  from  the  vessels  of  the  ciliary  processes. 

Some  anatomists  believe  that  these  vessels  send  ramifications  between  the  different 
concentric  laminae  of  the  crystalline  lens  for  its  nutrition ;  but  I  am  not  aware  that  they 
have  ever  been  demonstrated. 

No  nerves  have  been  discovered  in  the  crystalline  lens.  M.  Duges  believes  that  the 
retina  gives  off  some  net  vous  filaments  which  reach  as  far  as  the  lens,  and  spread  out 
upon  its  capsule ;  but,  after  the  most  careful  examination,  I  am  convinced  that  such  is 
not  the  case. 

The  Aqueous  Humour  and,  its  Membrane. 

The  term  aqueous  humour  is  applied  to  a  perfectly  limpid  and  transparent  fluid,  which 
occupies  the  two  chambers  of  the  eye.  These  two  chambers,  which  have  been  correctly 
understood  only  since  the  discovery  of  the  true  seat  of  cataract  in  the  crystalline  lens, 
correspond  to  that  small  portion  of  the  cavity  of  the  eye  which  is  situated  between  the 
cornea  and  the  lens  {see  fig.  241).  The  space  between  these  two  parts  is  divided  un- 
equally by  the  iris  (i)  into  two  chambers  :  an  anterior  and  larger,  which  is  called  the  an- 
terior chamber;  and  a  posterior  and  smaller,  named  the  -posterior  chamber.  These  two 
chambers  communicate  through  the  pupil  (jpi).  The  existence  of  the  posterior  chamber 
was  long  disputed,  but  it  may  easily  be  proved  by  freezing  the  eye  ;  and  by  the  same 
experiment  we  may  obtain  an  approximation  to  the  relative  capacity  of  the  two  cham- 
bers, which  will  be  found  as  3  to  1,  the  anterior  being  decidedly  the  larger. 

The  total  quantity  of  the  aqueous  humour  is  about  five  grains ;  100  parts  of  it  are 
found  to  contain  981  of  water,  with  traces  of  albumen  and  chloride  of  sodium. 

The  Membrane  of  the  Aqueous  Humour. — It  is  now  generally  admitted  that  the  aqueous 
humour  is  secreted  by  a  special  membrane,  called  the  membrane  of  the  aqueous  humour,  or 
membrane  of  Demours,  although  it  had  been  previously  described  by  Zinn  and  Descemet. 
This  membrane,  according  to  Demours,  hues  the  posterior  surface  of  the  cornea  {m,fig. 
241),  and  is  reflected  upon  the  front  of  the  iris.  At  this  point,  according  to  most  anat- 
omists, it  is  lost,  and  cannot  be  traced  to  the  pupil ;  but,  according  to  others,  it  proceeds 
as  far  as  the  pupil,  and  there  terminates ;  and,  lastly,  some  believe  that  it  is  reflected 
through  the  pupil,  in  order  to  cover  the  posterior  surface  of  the  iris,  where  it  retains  the 
pigment  in  its  situation. 

It  is  easy  to  detach  a  tolerably  thick  and  strong  layer,  of  a  cartilaginous  aspect,  from 
the  posterior  surface  of  the  cornea,  either  after  long-continued  maceration,  or  after  slight 
boiling ;  but  it  is  not  shown  that  this  is  anything  more  than  the  posterior  layer  of  the 
cornea,  which  it  resembles  in  appearance. 

It  is  only  from  analogy  that  the  existence  of  the  membrane  of  the  aqueous  humour 
can  be  admitted. 

We  cannot  demonstrate  anatomically  its  reflection  upon  the  outer  border  of  the  iris ; 
and,  moreover,  it  is  certain  that  it  does  not  exist  upon  either  surface  of  that  membrane. 

According  to  M.  Ribes,  the  aqueous  humour  is  supplied  by  the  vitreous  body,  and  is 
poured  into  the  posterior  chamber  by  the  canals  said  by  him  to  exist  in  the  substance  of 
the  ciliary  processes  of  the  vitreous  body.  This  opinion  is  founded,  1.  Upon  an  exper- 
iment which  consists  in  carefully  removing  the  cornea,  and  suspending  the  eye  by  the 
optic  nerve,  when  the  vitreous  humour  will  exude  from  the  wound  of  the  cornea,  so  that, 
in  less  than  twenty-four  hours,  two  thirds  of  that  body  will  have  escaped  ;  and,  2.  Upon 
the  observation  of  cases  of  imperfect  iris,  in  which,  according  to  M.  Ribes,  the  aqueous 
Fig.  250.  • 

—   -  sequently  become  dentated  ;  the  lens,  therefore,  resembles  some  other  non-vascular  parts 

(as  the  horny  tissues)  in  its  mode  of  growth.  It  consists,  according  to  Berzelius,  of  58"0 
per  cent,  of  water,  3'7  of  extractive  and  salts,  2'4  of  membrane,  and  35"9  of  a  peculiar 
Bubstanee,  which,  except  in  its  colour,  resembles  the  colouring  matter  of  the  blood. 

*  According  to  M.  Ribes,  whom  I  always  have  pleasure  in  quoting,  btcause  his  re- 
searches are  worthy  of  every  confidence,  "  by  examining  the  internal  surface  of  the  crys- 
talUne  capsule  in  a  good  light,  and  with  a  good  lens,  a  series  of  transverse  fissures  are 
observed  around  its  entire  circumference,  where  the  anterior  and  posterior  segments  of 
the  capsule  unite.  I  could  never  satisfy  myself  whether  these  fissures  corresponded  to 
the  ciliary  processes  of  the  vitreous  body,  or  to  the  villous  fringes  of  the  ciliary  processes 
of  the  choroid." 

T  Vide  fig.  v.,  pi.  6,  of  Soemmering's  Icones  Oculi  Humani. 


THE    ORGAN    OP   HEARING. 

Bnrhdur  is  contained  entirely  in  the  posterior  chamber.  He  believes  that  the  free  por- 
tion of  the  vitreous  ciliary  body  has  the  power  of  absorbing  this  liquid. 

M.  Duges  adopts  the  following  modification  of  this  opinion :  the  canal  of  Petit,  accord- 
ing to  him,  is  divided  into  as  many  compartments  as  there  are  ciliary  processes.  It  re- 
sembles, therefore,  a  collection  of  short  canals  directed  from  before  backward,  rather 
than  a  single  circular  canal ;  these  short  canals  communicate  behind  with  the  vitreous 
body,  and  open  in  front  by  certain  slits  or  perforations  existing  in  the  Zone  of  Zinn,  which 
enable  the  aqueous  humour  secreted  by  the  vitreous  body  to  escape  in  front  of  the  crys- 
talline lens. 

Haller  has  stated  all  the  opinions  which  have  been  entertained  regarding  the  produc- 
tion of  the  aqueous  humour,  which  has  been  said  to  be  secreted  by  the  vitreous  body, 
as  believed  by  MM.  Ribes  and  Duges,  by  the  ciliary  processes,  by  the  choroid,  by  the 
iris,  and,  lastly,  by  certain  special  ducts  proceeding  from  without  the  eye,  and  perfora- 
ting the  sclerotic  at  its  junction  with  the  cornea. 

The  Vessels  and  JVerves  of  the  Eye. 

The  arteries  of  the  eye  are  the  following  :  a  considerable  number  of  short  posterior  cil- 
iary arteries,  which  surround  the  optic  nerve,  perforate  the  sclerotic  near  it,  and  ramify 
in  the  choroid,  m  the  ciliary  processes,  and  in  the  iris  ;  the  anterior  short  ciliary,  which 
perforate  the  anterior  part  of  the  sclerotic,  and  are  distributed  to  the  iris  ;  the  long  cilia- 
ry arteries,  two  in  number,  which  run  between  the  sclerotic  and  the  choroid,  as  far  as 
the  outer  border  of  the  iris,  and  then,  bifurcating  and  curving  inward,  anastomose  with 
each  other  around  that  border.  From  the  vascular  circle  thus  formed  most  of  the  ves- 
sels of  the  iris  are  given  off.  The  central  artery  of  the  retina  {arleria  centralis  retina)  en- 
ters the  globe  of  the  eye  through  the  centre  of  the  optic  nerve  (at  the  porus  opticus,  b, 
fig.  246),  and,  sending  off  a  branch  to  the  crystalline  lens,  which  traverses  the  vitreous 
body  from  behind  forward,  covers  the  internal  surface  of  the  retina  with  its  other  rami- 
fications. 

The  veins  correspond  to  the  arteries,  but  are  much  more  numerous.  The  posterior, 
or  short  ciliary  veins,  form  vortices  or  whorls  in  the  choroid,  and  are  hence  called  vasa 
vorticosa  (v,  fig.  244).  All  the  veins  of  the  globe  of  the  eye  open  into  the  ophthalmic  and 
angular  veins. 

The  nerves  of  the  eye  consist  of  a  special  nerve  called  the  optic  nerve,  the  origin,  course, 
and  structure  of  which  will  be  described  hereafter  (see  Cranial  Nerves)  ;  and,  second- 
ly, of  the  ciliary  nerves,  which  are  derived  from  the  fifth  nerve,  either  directly  from  its 
nasal  branch,  or  indirectly  from  the  ophthalmic  ganglion.  These  nerves  (a  a,  fig.  242) 
are  distributed  to  the  ciliary  ligament,  and  to  the  iris. 

The  Organ  of  Hearing 

Hearing  is  that  sense  by  which  we  perceive  the  vibrations  of  the  air,  which  produce 
tound. 

The  organ  of  hearing  is  not  situated  in  the  face,  like  those  of  the  other  senses,  but  is 
contained  in  the  substance  of  the  base  of  the  cranium,  in  the  petrous  portion  of  the  tem- 
poral bone,  its  deep  situation  preserving  it  from  external  violence  :  it  is  composed  essen- 
tially of  a  membranous  and  nervous  apparatus  contained  in  an  extremely  complicated 
osseous  cavity,  named  the  labyrinth  or  internal  ear. 

The  labyrinth  if,  fig.  251)  communicates  with  the  exterior  by  means  of  an  acoustic 
trumpet  formed  by  the  auricle,  or  pinna  (a),  and  external  audita-  p^g  251. 

ry  meatus  (b),  and  named  the  external  ear,  which  may  be  regard- 
ed as  an  apparatus  for  collecting  sonorous  undulations. 

The  term  middle  ear,  or  tympanum,  is  applied  to  a  cavity  (d) 
which  is  placed  between  the  labyrinth  and  the  external  ear,  and 
may  be  considered  as  an  apparatus  for  modifying  sounds,  the 
intensity  of  which  is  increased  or  diminished  by  it,  according 
as  they  happen  to  be  weak  or  loud.*  It  follows,  therefore,  that 
the  ear  is  formed  by  a  succession  of  cayities,  which,  proceed- 
ing from  without  inward,  are,  the  external  ear,  consisting  of 
the  auricle  and  external  auditory  meatus,  of  the  middle  ear,  or 
tympanum,  and  of  the  internal  ear,  or  labyrinth.  I  shall  de- 
scribe the  ear  in  this  order,  and  shall  thus  proceed  from  the  less  to  the  more  complica- 
ted parts  of  this  organ. 

The  External  Ear. 

The  exiexnal  ear  resembles  a  funnel  or  ear-trumpet,  the  expanded  part  of  which  rep- 
resents the  auricle,  while  the  contracted  portion  corresponds  to  the  external  auditory 
meatus.  + 

*  M.  Richerand  (Elemens  de  Physiologie,  first  edit.)  has  drawn  an  excellent  comparison  lictween  the  uses  of 
the  tympanum  in  hearing-,  and  those  of  the  iris  in  vision. 

1  The  external  ear,  properly  speaking,  only  exists  in  mammalia-  and  eren  among-  mammalia,  those  -which 
do  not  hve  constantly  in  the  air  are  not  proirjded  with  it. 

4P 


NEUROLOGY 


The  Auricle. 

The  auricle  of  the  ear  {auricula,  'pimia),  commonly  called  the  ear,  is  placed  at  the  side 
of  the  head,  behind  the  articulation  of  the  lower  jaw,  and  in  front  of  the  mastoid  process ; 
it  is  an  oval  elastic  lamina,  folded  in  various  ways  upon  itself,  and  having  an  undulated 
surface. 

The  auricle  or  pinna  is  free  above,  behind,  and  below,  but  is  so  firmly  attached  in  front 
and  on  the  inner  side,  that  the  two  ears  can  support  the  weight  of  the  entire  body. 

The  individual  varieties  in  the  shape,  direction,  prominence,  and  size  of  the  auricle 
are  generally  known.  Of  these  varieties,  some  are  congenital,  and  others  acquired. 
Among  the  latter  should  be  noticed  the  effects  produced  by  the  habit  of  confining  the 
entire  ear  more  or  less  closely  by  the  head-dress.  The  direction  or  prominence  of  the 
auricle  is  not  without  some  influence  upon  hearing,  the  perfection  of  which  sense,  ac- 
cording to  Mr.  Buchanan,  depends  on  the  kind  of  angle  formed  by  the  auricle  with  the 
side  of  the  face,  and  which  should  be  from  25°  to  30°. 

The  internal  or  mastoid  surface  of  the  auricle  presents  certain  eminences  and  depres- 
sions, which  correspond  inversely  with  those  on  its  external  surface. 
The  external  surface  is  remarkable  for  the  alternate  ridges  and  depressions  observed 
Fig.  252.  upon  it :  at  its  centre,  but  somewhat  nearer  to  the  lower  than  the  up- 

per part,  we  find  the  concha  (a,  fig.  252),  a  funnel-shaped  excavation, 
the  form  and  expansion  of  which  are  familiar  to  all,  and  at  the  fore 
part  of  the  bottom  of  which  is  found  the  orifice  of  the  external  audito- 
ry meatus. 

The  concha  is  bounded  in  front  by  the  tragus  {h  ),  a  triangular  pro- 
cess, the  adherent  base  of  which  is  turned  forward  and  inward,  while 
iM^n~JljiS^  its  free  apex  is  directed  backward  and  outward :  it  advances  like  a 
lid  over  the  orifice  of  the  external  auditory  meatus,  which  is  com- 
pletely closed  by  its  depression.  The  posterior  surface  of  the  tragus, 
which  forms  part  of  the  concha,  is  covered  with  stiff  hairs,  especially 
in  old  subjects  ;  whence  its  name  of  tragus,  from  rpdyog,  a  goat.  The 
use  of  these  hairs  is  to  arrest  any  small  particles  that  are  floating  in  the  air. 

Behind  and  below,  that  is,  opposite  the  tragus,  the  concha  is  bounded  by  the  anti-tra- 
gus  (c),  a  triangular  tongue,  which  is  smaller  than  the  tragus,  and  is  separated  from  it 
by  a  wide,  deep,  and  rounded  notch,  named  the  notch  of  the  concha  (incisura  tragica). 

Behind  and  above,  the  concha  is  bounded  by  the  anti-helix  (e),  a  curved  fold,  which 
commences  above  the  anti-tragus,  being  separated  from  that  part  by  a  slight  depression, 
passes  upward  and  forward,  bifurcates,  and  then  ends  in  the  groove  of  the  helix.  The 
superior  branch  of  the  bifurcation  of  the  anti-helix  is  broad  and  smooth,  while  the  inferi- 
or is  sharp  ;  between  them  is  situated  a  slight  depression,  called  the  scaphoid,  or  navicv^ 
lar  fossa,  but  which  would  be  more  correctly  named  Vae  fossa  of  the  anti-helix  (/). 

The  term  helix  {ili^,  a  roll,  from  kTiiacu,  to  roll  around)  is  applied  to  a  curved  fold 
{g  g),  which  forms  the  external  border  of  the  auricle  :  it  commences  in  the  cavity  of  the 
concha,  which  it  divides  into  two  unequal  parts,  one  superior  and  narrow,  the  other  in- 
ferior and  broader ;  gradually  increasing  in  size,  it  then  passes  upward  and  forward  above 
the  external  meatus,  then  above  the  tragus,  from  which  it  is  separated  by  a  very  distinct 
furrow :  it  next  runs  directly  upward,  curves  backward,  descends  to  form  the  posterior 
margin  of  the  auricle,  and  terminates  by  becoming  continuous  with  the  anti-helix  in 
front,  and  with  the  lobule  {I)  behind. 

The  groove  or  furrow  of  the  helix  is  the  groove  (i)  which  surrounds  the  helix,  and  sep- 
arates it  from  the  anti-helix. 

The  lobule  occupies  the  lower  or  small  extremity  of  the  auricle,  from  the  rest  of  which 
it  is  distinguished  by  its  softness ;  it  is  surmounted  by  the  tragus  in  front,  by  the  anti- 
tragus  behind,  and  by  the  notch  of  the  concha  in  the  middle.  The  lobule  of  the  ear  va- 
ries exceedingly  in  size  in  different  individuals,  and  is  the  part  to  which  ear-rings  are 
generally  appended. 

The  Structure  of  the  Auricle. — The  cartilage  of  the  ear  {figs.  253,  253*)  constitutes  the 


Fig.  253. 


Fig.  253.* 


framework  of  the  auricle,  in  a  great  measure  deter- 
mines its  shape,  and  is  the  cause  of  its  phability  and 
elasticity. 

When  the  skin  is  removed  from  it,  this  cartilage, 
therefore,  presents  certain  eminences  and  depressions, 
corresponding,  with  some  exceptions,  to  those  already 
described  as  existing  upon  the  surface  of  the  auricle. 
The  cartilage  of  the  ear  has  no  part  corresponding  with 
the  lobule  :  again,  the  cartilaginous  fold  which  consti- 
tutes the  helix  terminates  at  the  middle  of  the  concha, 
from  whence  it  is  continued  by  a  fold  of  skin,  which, 
moreover,  covers  it  throughout,  and  increases  its  prominence.  Upon  the  cartilage  of  the 
auricle  we  also  observe  the  following  parts :  1.  A  mammillated  eminence  {a,  fig.  253V 


THE    AURICLE.  667 

called  the  p-ocess  of  the  helix  :  it  is  of  considerable  size,  is  very  dense,  and  arises  from 
the  anterior  margin  of  the  helix,  above  the  tragus.  This  process  gives  attachment  to  a 
ligament. 

2.  A  tail-shaped  tongue  of  .cartilage  (5),  separated  from  that  of  the  anti-tragus  and 
concha  by  a  very  long  fissure,  which  is  occupied  by  ligamentous  fibres.  This  tongue  is 
formed  by  the  united  ends  of  the  helix  and  anti-helix,  and  is  very  thick  and  dense : 
it  may  be  called  the  caudal  extremity  of  the  helix  and  anti-helix ;  it  supports  the  base  of  the 
lobule. 

3.  A  well-marked  thickening,  situated  opposite  the  concha,  and  characterized  by  a 
dead  white  colour.  This  thickening  occupies  a  vertically  elongated  portion  of  the  mas- 
toid surface  of  the  concha,  and  terminates  at  the  lower  part  of  the  auricular  cartilage  : 
it  seems  to  be  intended  to  preserve  the  form  of  the  concha,  which  cannot  be  flattened 
unless  this  thickened  portion  of  the  cartilage  is  first  divided.  Several  fissures  or  notch- 
es are  also  found  in  the  cartilage  of  the  ear,  which  is  thus  imperfectly  divided  into  sev- 
eral pieces  that  are  movable  upon  each  other,  and  united  together  by  ligaments.  The 
principal  fissure,  independently  of  that  already  described  as  existing  between  the  anti- 
tragus  and  the  caudal  extremity  of  the  helix  and  anti-helix,  are,  a  small  vertical  fissure 
upon  the  anterior  margin  of  the  heUx  ;  another  vertical  fissure  upon  the  tragus  ;  several 
irregular  notches  in  the  helix ;  and,  lastly,  a  much  more  important  fissure,  to  which  I 
shall  have  to  allude  in  describing  the  external  auditory  meatus.  It  is  situated  between 
the  helix  and  the  tragus,  and  is  prolonged  upon  the  outer  half  of  the  orifice  of  that  meatus. 

The  skin  of  the  auricle  is  remarkable  for  its  thinness  and  transparency :  hence  the 
sub-cutaneous  vascular  network  can  be  seen  through  it  without  dissection  ;  it  is  no  less 
remarkable  for  its  tension,  and  its  close  adhesion  to  the  cartilage,  upon  which  it  is  mould- 
ed, so  as  accurately  to  reveal  its  form.  The  portion  of  skin  which  covers  the  concha  is 
especially  remarkable  for  its  great  tenuity  and  intimate  adhesion  to  the  cartilage. 

The  skin  upon  the  free  border  of  the  auricle  adheres  but  slightly  to,  and  projects  be- 
yond the  helix ;  the  same  fold  of  skin,  when  doubled  upon  itself  and  prolonged  below  the 
helix,  constitutes  the  lobule,  which,  together  with  the  adjacent  part  of  the  free  border 
of  the  auricle,  is  nothing  more  than  a  duplicature  of  the  skin,  containing  some  soft  fat. 
A  small  quantity  of  fat  is  formed  around  the  entire  circumference  of  the  auricle,  but 
none  exists  in  other  situations. 

The  skin  of  the  ear  is  provided  with  sebaceous  folhcles,  which  can  be  easily  shown  by 
maceration,  after  the  method  employed  by  Soemmering,  and  which  are  most  numerous 
in  the  concha  and  the  scaphoid  fossa. 

The  ligaments  of  the  auricle  are  divided  into  the  intrinsic  and  the  extrinsic  ligaments. 

The  extrinsic  ligaments  are,  the  posterior  ligament,  which  is  a  thick,  tendinous  layer,  ex- 
tending from  the  concha  to  the  mastoid  process  ;  the  anterior  ligament,  which  is  a  triangu- 
lar, very  broad,  and  very  strong  hgament,  arising  from  the  process  of  the  helix  and  the  ad- 
jacent part  of  the  border  of  the  helix,  and  terminating  at  the  zygomatic  arch,  where  it  is 
blended  with  the  superficial  temporal  fascia  ;  and,  lastly,  the  ligament  of  the  tragus,  which 
is  very  strong,  and  extends  from  the  tragus  to  the  adjacent  part  of  the  zygomatic  arch. 

The  intrinsic  ligaments,  the  object  of  which  is  to  keep  the  cartilage  of  the  auricle  fold- 
ed upon  itself,  are,  the  ligament  which  keeps  the  caudal  extremity  of  the  helix  applied 
to  the  concha ;  the  very  strong  ligament  which  extends  from  the  tragus  to  the  helix,  and 
.  unites  the  outer  half  of  the  auditory  meatus  to  the  cartilage  of  the  auricle  ;  some  very 
strong  bundles,  which  are  situated  upon  the  mastoid  surface  of  the  auricle,  and  are  in- 
tended to  preserve  its  convolutions,  for  when  they  are  divided  the  auricle  may  be  un- 
folded ;  lastly,  those  most  remarkable  ligamentous  bundles,  which  occupy  the  fold  pre- 
sented by  the  inferior  branch  of  the  bifurcation  of  the  anti-helix. 

The  three  extrinsic  muscles  of  the  ear,  which  exist  in  a  rudimentary  condition  in  the 
human  subject,  but  are  so  highly  developed  in  timid  animals,  are  intended  to  move  the 
auricle  as  a  whole  (see  Myology). 

The  intrinsic  muscles  move  the  different  parts  of  the  auricular  cartilage  upon  each  oth- 
er. Like  the  extrinsic,  they  are  quite  rudimentary.  There  is  no  difference  in  their  size 
in  savage  and  civilized  races.  They  are  five  in  number,  four  of  them  being  situated  on 
the  concave,  and  one  only  on  the  convex,  or  mastoid  surface  of  the  auricle. 

The  great  muscle  of  the  helix  (helicis  major,  c,  fig.  253)  is  situated  vertically  upon  the 
anterior  part  of  the  helix,  near  the  tragus  ;  it  is  a  narrow,  oblong  tongue,  fleshy  in  the 
middle,  and  tendinous  at  its  extremities  ;  its  fibres  are  vertical. 

The  small  muscle  of  the  helix  (helicis  minor,  d),  the  smallest  of  the  intrinsic  muscles  of 
the  ear,  lies  upon  that  portion  of  the  helix  which  divides  the  concha  into  two  parts. 

The  muscle  of  the  tragus  (tragicus,  e)  is  a  broad  band,  lying  upon  the  external  surface 
of  the  tragus  ;  its  fibres  are  directed  vertically. 

The  muscle  of  the  anti-tragus  (anti-tragicus,/)  is  a  tongue-like  bundle,  which  covers 
the  external  surface  of  the  anti-tragus,  and  is  inserted  by  a  tendon  to  the  upper  part  of 
the  caudal  extremity  of  the  helix.  Its  use  may  be  to  move  this  caudal  extremity  upon 
the  anti-tragus. 

The  fifth  is  the  transverse  muscle  (transversus  auriculae,  a,  fig.  353*),  which  is  situated 

4 


NEUROLOGY. 

on  the  mastoid  surface  of  the  auricle.  According  to  Soemmering,  it  consists  of  a  trans- 
verse layer  of  fibres  of  unequal  length,  which  spread  out  in  a  semicircular  form  from  the 
convexity  of  the  concha  to  the  ridge,  corresponding  to  the  groove  of  the  helix.  I  doubt 
the  muscularity  of  these  fibres,  which  I  am  inclined  to  regard  as  constituting  an  intrin- 
sic ligament  intended  to  preserve  the  fold  of  that  portion  of  the  anti-helix  by  which  the 
concha  is  bounded  behind  and  above. 

The  arteries  of  the  auricle  are  the  posterior  auricular,  a  remarkable  branch  of  which 
passes  through  the  cartilage,  between  the  caudal  extremity  of  the  helix  and  the  concha, 
so  as  to  ramify  in  the  cavity  of  the  concha.  All  the  branches  of  the  posterior  auricular 
arteries  turn  over  the  free  border  of  the  helix,  so  as  to  reach  the  concave  surface  of  the 
auricle.  The  anterior  auricular  arteries  arise  from  the  external  carotid  and  the  tempo- 
ral, and  divide  into  inferior  branches  or  arteries  of  the  lobule  and  ascending  branches. 
The  vei7is  have  the  same  names  and  follow  the  same  course  as  the  arteries. 

The  nerves  of  the  auricle  are  derived  from  the  auricular  branch  of  the  cervical  plexus  ; 
three  or  four  of  them  ramify  upon  the  internal  surface  of  the  auricle.  A  remarkable  branch 
perforates  the  cartilage  between  the  anti-tragus  and  the  caudal  extremity  of  the  helix, 
and  is  distributed  to  the  skin  which  lines  the  concha.* 

The  External  Auditory  Meatus. 

The  external  auditory  meatus  {b,fig.  251)  is  a  partly  cartilaginous  and  partly  osseous 
canal,  extending  from  the  concha  (a)  to  the  membrane  of  the  tympanum  (c).  It  fonns  the 
narrow  portion  of  the  ear-trumpet  represented  by  the  external  ear. 

It  is  about  an  inch  in  length.  Its  section  represents  an  ellipse,  of  which  the  longest 
diameter  is  vertical.  Its  direction  is  transverse,  and  it  describes  a  very  slight  curve, 
having  its  convexity  turned  upward.  Moreover,  near  its  external  orifice  it  is  bent  at  an 
angle  which  projects  upward,  and  hence  it  is  necessary  to  draw  the  auricle  upward  and 
backward,  if  we  wish  to  examine  the  bottom  of  the  external  auditory  meatus. 

The  external  meatus  is  in  relation  with  the  temporo-maxillary  articulation  in  front, 
with  the  mastoid  process  behind,  and  with  the  parotid  gland  below. 

Its  external  orifice,  which  is  vertically  oblong,  more  or  less  widened  out  in  different  in- 
dividuals, and  covered  with  hairs  in  old  age,  occupies  the  anterior  and  inferior  part  of 
the  concha  behind  the  tragus,  which  serves  as  a  lid  for  it.  It  is  bounded  behind  by  a 
sort  of  semilunar  ridge,  which  projects  more  or  less  forward  in  different  individuals,  so 
as  to  contract  its  orifice  to  a  greater  or  less  extent.  In  front  of  the  auditory  meatus 
there  is  an  excavation  or  fossa  concealed  by  the  tragus,  and  named  the  tragic  fossa  of 
the  co7icha ;  it  forms,  as  it  were,  the  vestibule  of  the  meatus. 

The  internal  orifice  of  the  auditory  meatus  is  circular :  it  is  directed  very  obliquely 
downward  and  inward,  and  is  closed  by  the  membrana  tympani. 

Structure. — The  auditory  meatus  consists  of  an  osseous  portion,  and  of  a  cartilaginous 
and  fibrous  part. 

The  osseous  portion  has  been  already  described  with  the  temporal  bone,  as  the  external 
auditory  meatus.  It  is  wanting  in  the  foetus,  and  in  the  new-born  infant,  in  whicli  its 
place  is  supplied  by  the  tympanic  ring  or  circle.  We  have  stated  that,  in  the  adult,  this 
ring  forms  an  osseous  lamina  distinct  from  the  rest  of  the  temporal  bone,  that  it  rests 
behind  upon  the  mastoid  and  styloid  processes,  for  the  latter  of  which  it  forms  the  vagi- 
nal process,  and  that  it  is  separated  in  front  from  the  auricular  portion  of  the  glenoid 
cavity  by  the  fissure  of  Glasserius  ;  this  lamina  forms  both  the  anterior  and  inferior  walls 
of  the  auditory  meatus  and  cavity  of  the  tympanum. 

The  cartilaginous  and  fibrous  portion  forms  the  outer  half  of  the  external  auditory  mea- 
tus, and  may  be  separated  from  the  cartilage  of  the  auricle  by  a  careful  dissection.  If 
an  incision  be  made  over  the  similunar  ridge  which  constitutes  the  outer  border  of  the 
orifice  of  the  auditory  meatus,  it  will  be  seen  that  this  ridge  is  formed  by  the  juxtaposi- 
tion of  two  cartilaginous  borders,  one  of  which  belongs  to  the  concha,  and  the  other  to 
the  auricle,  and  which  are  united  by  fibrous  tissue.  If  the  dissection  be  continued  be- 
tween the  tragus  and  the  corresponding  part  of  the  helix,  the  auricle  may  be  separated 
from  the  auditory  meatus,  exceping  below,  where  their  continuity  is  established  by  means 
of  a  tongue  or  isthmus  of  cartilage. 

The  tragus  belongs  essentially  to  the  auditory  meatus,  the  cartilage  of  that  canal  being 
merely  a  prolongation  of  the  tragus  folded  upon  itself  (see  b,fig.  253*),  so  as  to  form- the 
lower  two  thirds  or  three  fourths  of  a  cylinder.  The  inner  end  of  this  imperfect  cylin- 
der is  attached  to  the  rough  external  rim  oi  the  osseous  portion  of  the  meatus  by  means 
of  a  fibrous  tissue,  which  extends  farther  above  and  behind  than  below  and  in  front,  and 
which  gives  the  cartilage  a  great  degree  of  mobility ;  there  is  a  thick  prolongation  or 
process  at  the  lower  and  anterior  part  of  the  inner  end  of  the  cartilage  of  the  meatus. 

The  fibrous  portion  of  the  auditory  meatus  forms  the  upper  third  or  fourth  of  that  canal, 
and  also  fills  up  the  large  notch  in  the  inner  end  of  the  cartilaginous  portion. 

*  [The  auricle  also  receives  twigs  from  the  posterior  auricular  branch  of  the  facial  nerve,  from  the  auriculo- 
temporal branch  of  the  inferior  maxillary  division  of  the  fifth  nerve,  and  from  a  small  branch  of  the  pneumo- 
fastric  nerve.     See  description  of  those  nerves.] 


THE   TYMPANOM. 

Near  the  tragus  there  are  two  or  three  fissures  or  divisions  in  this  cartilage,  named 
the  fissures  of  Santorini,  which  give  it  some  resemblance  to  the  rings  of  the  trachea  : 
these  fissures  are  at  right  angles  to  the  length  of  the  canal,  and  are  filled  up  with  a 
fibrous  tissue,  which  some  anatomists  have  conceived  to  be  mixed  with  muscular  fibres, 
or  to  consist  entirely  of  muscular  fibres  intended  to  move  the  small  and  partially  separa- 
ted portions  of  the  cartilage.  It  is  evident  that  the  mode  in  which  the  partly  cartila- 
ginous and  partly  fibrous  portion  is  united  with  the  osseous  portion  of  the  canal,  and  also 
the  existence  of  the  fissures  just  described,  have  reference  to  the  mobility  of  the  entire 
canal. 

The  internal  surface  of  the  auditory  meatus  is  lined  by  a  prolongation  of  the  shin, 
which  is  remarkable  for  its  extreme  thinness.  It  becomes  thinner  and  thinner  in  ad- 
vancing from  the  orifice  to  the  bottom  of  the  meatus  ;  and  the  fineness  and  extreme  del- 
icacy of  that  portion  of  the  skin  which  corresponds  to  the  osseous  part  of  the  meatus 
deserves  special  attention.  The  skin  of  the  meatus  is  also  characterized  by  being  cov- 
ered in  all  parts  with  fine  downy  hairs  ;  a  fact  which  proves  that  it  is  of  a  cutaneous 
structure,  and  not  a  mucous  membrane.  In  old  subjects,  there  are  some  tolerably  long 
hairs  at  the  commencement  of  the  auditory  meatus,  as  well  as  upon  the  internal  surface 
of  the  tragus ;  they  prevent  the  entrance  of  dust  and  insects,  which,  moreover,  get  in- 
volved in  the  ceruminous  secretion. 

The  skin  of  the  meatus  is  farther  characterized  by  the  presence  of  a  number  of  se- 
baceous follicles,  or  glands,  called  the  ceruminous  glands,*  the  orifices  of  which  are  vis- 
ible to  the  naked  eye,  and  give  the  skin  an  areolar  appearance.  These  small  glands  oc- 
cupy the  entire  inner  surface  of  the  cartilaginous  and  fibrous  portions  of  the  auditory 
meatus  :  from  their  yellowish-brown  colour,  they  can  be  readily  seen  in  oblique  sections 
of  the  skin.  They  secrete  a  rather  thick  unctuous  substance,  resembling  wax,  whence 
it  is  called  cerumen  {cera,  wax).  It  is  very  bitter,  and  is  partially  soluble  in  water,  with 
which  it  forms  an  emulsion  which  leaves  a  greasy  stain  upon  paper ;  it  sometimes  be- 
comes exceedingly  hard  from  remaining  long  in  the  passage,  and  then  acts  as  a  mechan- 
ical cause  of  deafness.  By  analysis,  this  substance,  according  to  Berzelius,  yields  a 
fatty  oil,  an  albuminous  substance,  and  a  colouring  matter,  and,  according  to  Rudolphi, 
a  bitter  principle  like  that  of  the  bile.  Nature  intended,  says  Soemmering,  that  there 
should  be  a  sufficient  quantity  of  cerumen,  not  only  to  keep  out  insects,  but  also  to  di- 
minish the  intensity  of  sonorous  vibrations.  It  is,  therefore,  a  bad  habit  to  remove  it 
artificially,  unless  there  be  an  abnormal  accumulation  of  this  substance. 

The  Middle  Ear,  or  Tympanum. 

Dissection. — The  cavity  of  the  tympanum  may  be  laid  open,  either  from  its  external 
wall,  by  removing  the  membrana  tympani,  or  from  its  upper  wjdl,  by  cutting  away  the 
anterior  part  of  the  base  of  the  petrous  portion  of  the  temporal  bone  with  a  strong  scal- 
pel ;  the  situation  in  which  this  may  be  done  is  indicated  by  a  fissure,  or,  rather,  a  su- 
ture, which  exists  between  the  petrous  and  squamous  portions  ;  lastly,  the  tympanum 
may  be  opened  from  its  lower  M^all,  by  breaking  down  the  osseous  plate  of  the  auditory 
meatus. 

In  order  to  show  all  the  parts  contained  in  the  cavity  of  the  tjTnpanum,  several  speci- 
mens should  be  prepared  in  different  ways.  It  is  of  importance,  moreover,  to  study  the 
ear  in  the  temporal  bones  of  the  adult  subject  and  the  fcetus,  as  well  in  macerated  speci- 
mens as  in  such  as  have  been  dried  without  previous  maceration. 

The  tympanum,  tympanic  cavity,  or  drum  of  the  ear  {tympanum,  a  drum,  d,  fig.  251),  is 
a  cavity  situated  between  the  external  auditory  meatus  (b)  and  the  labyrinth  or  interned 
ear  (/) ;  it  communicates  with  the  pharynx,  and,  consequently,  with  the  air-passages, 
by  means  of  the  Eustachian  tube  (e,  fig.  255) ;  it  is  prolonged  into  the  mastoid  process, 
by  means  of  the  mastoid  cells  (c),  and  it  is  traversed  by  a  chain  of  small  bones  (1,  2,  3), 
neuned  the  ossicula  audittis. 

The  tympanum  is  placed  in  the  anterior  part  of  the  base  of  the  petrous  portion  of  the 
temporal  bone,  above  the  osseous  lamina  of  the  external  meatus,  and  in  firont  of  the 
mastoid  process ;  it  is  directly  continuous  with  the  osseous  portion  of  the  Eustachian 
tube,  of  which  it  seems  only  to  be  a  dilatation. 

From  its  form,  which  is  otherwise  irregular,  or,  rather,  from  the  two  dry  membranes 
formed  upon  its  opposite  walls,  it  has  been  compared  to  a  military  drum ;  it  is  flattened 
from  without  inward,  so  that  its  transverse  diameter  is  the  shortest.  It  presents  for  our 
consideration  an  internal  and  an  external  wall,  and  a  circumference. 

The  External  Wall  of  the  Tympanum. — This  wall  is  formed  by  the  membrana  tympani, 
and  by  that  portion  of  the  temporal  bone  in  which  the  membrane  is  fitted.  This  portion 
of  the  temporal  bone  is  a  compact  lamina,  which  is  flat  in  the  human  subject,  but  ex 
tremely  prominent  in  some  animals. 

The  membrana  tympani  {c,fig.  251)  is  a  nearly  circular,  semi-transparent  membranous 
septum,  dry-looking  like  parchment,  and  vibratile  ;  it  is  situated  between  the  external 

*  [The  ceruminous  glands  consist  of  a  long-  conToluted  tube,  closed  at  one  end,  and  opening  by  the  other 
upon  the  internal  surface  of  the  meatus.] 


NEUROLOGY. 


auditory  meatus,  at  the  bottom  of  which  it  may  be  seen  in  the  living  subject,  and  the 
cavity  of  the  tympanum.  It  is  directed  very  obliquely  downward  and  inward ;  so  that, 
instead  of  passing  perpendicularly  across  the  auditory  meatus,  it  is  continuous,  at  a 
very  slight  angle,  with  the  upper  wall  of  that  canal.  In  consequence  of  this  obliquity, 
the  membrana  tympani  unites  with  the  lower  waU  of  the  meatus  at  an  angle  of  about  45°, 
and  the  meatus  itself  terminates  in  such  a  manner  that  its  lower  wall  is  much  longer 
than  the  upper. 

The  external  surface  of  the  membrana  t)mipani  is  free,  and  is  directed  downward  and 
outward ;  the  internal  surface  is  turned  upward  and  inward,  and  adheres  very  firmly  to 
the  handle  of  the  bone  of  the  ear,  called  the  malleus,  by  which  it  is  drawn  inward,  so 
that  its  centre  presents  a  funnel-shaped  depression,  which  is  concave  externally  and 
convex  within.  The  circumference  of  the  membrane  is  fitted,  like  a  watch-glass,  into  a 
circular  furrow  formed  at  the  inner  end  of  the  external  meatus  in  the  adult,  and  into  the 
tympanic  ring  in  the  foetus.  Above  and  behind,  near  its  insertion  into  its  bony  frame,  the 
membrana  tympani  is  elevated  by  a  small  process  (the  short  process)  of  the  malleus. 

Immediately  on  the  inner  side  of  the  insertion  of  the  membrana  tympani,  opposite  the 
posterior  extremity  of  a  line  drawn  across  its  middle,  is  situated  a  small  foramen,  the 
orifice  of  a  canal  which  transmits  the  chorda  tympani  nerve. 

Is  the  membrana  tympani  perforated  1  Some  anatomists  have  asserted  that  there  is 
an  aperture  between  the  membrane  and  the  bone,  at  one  point  of  its  circumference  ;  and 
others  have  believed  that  an  oblique  slit  traverses  the  membrane.  But  these  perfora- 
tions do  not  exist  in  the  natural  state  ;  so  that  the  membrana  tympani  forms  a  complete 
septum  between  the  tympanum  and  the  external  auditory  meatus. 

Notwithstanding  its  tenuity  and  transparency,  the  membrana  tympani  consists  of  three 
very  distinct  layers.  The  external  or  epidermic  layer  is  a  prolongation  of  the  epidermic 
portion  only  of  the  skin  which  lines  the  external  meatus. 

The  internal  or  mucous  layer  is  a  prolongation  of  the  extremely  thin  mucous  mem- 
brane which  lines  the  tympanum.  The  handle  of  the  malleus  is  situated  between  this 
and  the  middle  layer. 

The  middle  or  proper  layer,  on  which  the  strength  of  the  membrane  depends,  appears 
to  be  of  a  fibrous  nature.  According  to  Sir  Everard  Home,  it  is  muscular ;  he  states 
that  he  distinctly  saw  muscular  fibres  radiating  from  the  centre  to  the  circumference, 
first  in  the  elephant,  and  afterward  in  the  ox,  and  in  the  human  subject.* 

By  fine  injections  some  very  delicate  vessels  are  demonstrated  in  the  membrane. 
The  network  represented  by  Scemmering,  who  only  injected  the  arteries,  is  not  nearly 
so  dense  as  that  which  may  be  displayed  by  filling  the  veins.  If  a  blue  injection  be 
thrown  into  the  jugular  vein  of  the  foetus,  the  whole  membrane  will  become  of  that  col- 
our, and  will  present  an  exceedingly  fine  vascular  network  under  a  lens.  In  a  new-born 
infant,  which  had  died  with  inflammation  of  the  tympanum,  the  membrane  was  found 
quite  red.  The  bloodvessels  appear  to  be  situated  entirely  in  the  internal  layer ;  they 
run  from  the  circumference  towards  the  centre  of  the  membrane  ;  and  this  arrangement 
has  probably  led  to  the  supposition  of  the  existence  of  radiated  muscular  fibres. 

The  use  of  the  membrana  tympani  is  to  transmit  the  sonorous  vibrations  received 
through  the  external  auditory  meatus  to  the  air  contained  within  the  tympanum,  and  to 
the  ossicula  of  the  ear.  Its  obliquity,  besides  increasing  the  dimensions  of  this  vibratile 
membrane,  has  certainly  some  use  in  the  reflection  of  sonorous  vibrations.  As  it  ad- 
heres to  one  of  the  chains  of  small  bones  of  the  ear,  it  is  influenced  by  their  movements ; 


and  in  this  way  it  maybe  either  stretched  or  relaxed. 

The  Internal  Wall  of  the  Tympanum. — The  inter- 
nal wall  of  the  tympanum  {figs.  254,  255),  which  is 
perfectly  exposed  when  that  cavity  is  opened  from  its 
external  wall,  presents  a  great  number  of  objects  for 
our  consideration.  At  its  upper  part  is  situated  the 
fenestra  ovalis  if,  fig.  254),  the  long  diameter  of  which 
is  directed  transversely,  but  rather  obliquely  down- 
ward and  forward ;  the  upper  border  of  this  fenestra 
if,  fig.  258)  is  semi-elliptical,  while  the  lower  border 
is  straight,  or,  rather,  it  projects  somewhat  into  the 
opening.  The  fenestra  ovalis,  called  also  the  vestib- 
ular orifice  of  the  tympanum,  would  establish  a  free 
communication  between  the  tympanum  and  the  ves- 
tibule if  it  were  not  closed  by  the  base  of  the  stapes 
{d,fig.  255 ;  n,fig.  257),  which  is  accurately  fitted  to  it. 

The  fenestra  ovalis  is  placed  at  the  bottom  of  a 
depression,  which  is  named  the  fossette  of  the  fe- 
nestra, and  the  depth  of  which  depends  upon  the  de- 

*  Philosopliical  Transactions,  p.  23,  1823.  To  his  paper  are 
annexed  three  plates,  representing  the  membrana  tympani  in  the 
elephant,  the  ox,  and  man. 


tig.  254. 


Natural  size. 
(Section  of  the  tympanam.) 


THE   TYMPANUM. 


671 


gree  of  projection  of  the  aqueduct  of  Fallopius,  which  bounds  it  in  front,  by  that  of  the 
promontory,  which  is  below,  and  by  an  osseous  tongue  which  passes  up  to  the  pyramid 
behind. 

Below  the  fenestra  ovalis  is  the  promontory  (r,  figs.  254,  255),  an  eminence  which 
corresponds  to  the  first  turn  of  the  cochlea,  and  has  three  grooves  upon  its  surface, 
that  diverge  above  and  converge  below,  where  they  terminate  in  a  common  canal, 
which  opens  upon  the  lower  surface  of  the  petrous  portion  of  the  temporal  bone,  be- 
tween the  carotid  canal  and  the  groove  for  the  internal  jugular  vein.  This  canal  (ca- 
nalis  tympanicus,  Arnold)  may  be  called  the  canal  ofJacobson,  because  it  contains  Jacob- 
son's  nerve,  a  branch  given  off  from  the  glosso-pharyngeal,  which  establishes  a  very  re- 
markable anastomosis  between  the  glosso-pharyngeal  and  the  nervi  molles  derived  from 
the  vidian  and  great  sympathetic  nerves.*  The  furrows  upon  the  promontory  are  in- 
tended to  lodge  this  anastomosis.     They  are  often  formed  into  complete  canals. 

Behind  the  fenestra  ovalis,  and  opposite  its  transverse  diameter,  is  a  small  projection 
of  variable  size,  called  the  pyramid  {t,figs.  254,  255).  There  is  an  opening  upon  it  which 
is  distinctly  visible  to  the  naked  eye,  and  makes  the  p)Tamid  appear  tubular.  From  thia 
opening  emerges  a  small  cord  (o,  fig.  255),  the  nature  of  which  is  not  known,  but  which 
is  called  the  stapedius  muscle.  A  bristle  passed  into  this  opening  enters  the  canal  of  the 
pyramid,  which  canal  is  generally  described  as  ending  in  a  cul-de-sac,  but  this  is  not  the 
case.  M.  Huguier,  prosector  of  the  faculty,  has  clearly  demonstrated,  in  a  series  of 
preparations,  that  the  canal  of  the  pyramid  is  a  long  passage,  which  passes  backward 
and  downward  below  the  aqueduct  of  Fallopius,  becomes  vertical  like  the  aqueduct,  is 
separated  from  it  only  by  a  thin  lamina  of  bone,  communicates  with  it  by  a  small  open- 
ing, and  at  length  abandons  it  below,  to  open  upon  the  inferior  surface  of  the  petrous 
bone,  on  the  inner  side  of  the  stylo-mastoid  foramen,  at  a  variable  distance  from  it. 
Sometimes  this  canal  bifurcates  below ;  so  that  two  bristles  introduced  into  the  small 
openings  near  the  stylo-mastoid  foramen  will  both  enter  the  canal  of  the  pyramid.  A 
small,  very  short,  and  horizontal  passage,  which  terminates  in  the  diploe  of  the  tem- 
poral bone,  may  be  regarded  as  a  diverticulum  of  this  canal. 

I  have  already  stated  that  a  fibrous-looking  cord,  named  the  stapedius  muscle,  emerges 
from  the  canal  of  the  pyramid.  It  is  not  yet  known  what  structures  are  transmitted 
through  the  divisions  of  this  canal. 

Below  the  fenestra  ovalis,  and  behind  the  promontory,  is  situated  the  fenestra  rotunda 
(*,  figs.  254,  255) ;  it  is  placed  at  the  bottom  of  a  funnel-shaped  depression,  which  was 
well  described  by  M.  Ribes  as  the  fossa  of  the  fenestra  rotunda,  at  the  bottom  of  which 
is  found  a  partly  membranous  and  partly  osseous  lamina,  which  is  the  commencement 
of  the  spiral  septum  of  the  cochlea.  In  a  dry  bone,  which  has  been  previously  macerated, 
the  membranous  part  being  destroyed,  the  fossa  of  the  fenestra  rotunda  communicates 
with  the  vestibule.  Below  this  compound  lamina,  i.  e.,  at  the  lower  part  of  the  fossa 
just  described,  is  found  the  fenestra  rotunda  (*,  fig.  257)  properly  so  called,  which  leads 
into  the  tympanic  scala  of  the  cochlea  (l) ;  whence  the  term  cochlear  orifice  of  the  tym- 
panum is  applied  to  the  fenestra  rotunda,  in  contradistinction  to  the  term  vestibular  orifice, 
which  is  given  to  the  fenestra  ovalis. 

The  fenestra  rotunda  is  closed,  in  the  fresh  state,  by  a  membrane  called  the  secondary 
membrana  tympani,  which  is  said  to  be  composed  of  three  layers — a  middle  layer,  an 
external  or  tympanic,  and  an  internal  or  cochlear  layer.  The  two  last  named  are  mucous 
membranes.} 

Under  the  pyramid,  and  behind  the  fenestra  rotun- 
da, is  seen  a  deep  fossa,  the  sub-pyramidal  fossa  {v,fig, 
254),  remarkable  for  its  constancy,  and  pierced  by 
several  foramina  at  the  bottom. 

Upon  the  internal  wall  of  the  tympanum,  in  front 
of  the  fenestra  ovalis,  somewhat  above  the  trans- 
verse diameter  of  that  opening,  and  under  the  prom- 
inence of  the  aqueduct  of  Fallopius,  is  the  internal 
orifice  (n,  figs.  254,  255)  of  the  canal  (m)  for  the  internal  "\ 
muscle  of  the  malleus,  or  tensor  tympani  muscle.  This 
orifice  is  wide  and  cup-shaped,  and  is  supported  by  a 
hollow  eminence  (z,  jQ.  254),  which  is  itself  sustain- 
ed by  several  ridges ;  so  that  there  is  the  greatest 
analogy  between  it  and  the  hollow  projection  consti- 
tuting the  pyramid.  Both  of  them  transmit  a  tendon. 
One  is  situated  in  front,  and  the  other  behind  the  fe- 
nestra ovalis.  M.  Huguier,  who  has  paid  much  at- 
tention to  this  subject,  has  shown  that  the  cochleari- 

*  This  can  be  clearly  seen  in  some  preparations  in  the  museum 
of  the  Faculty  at  Paris. 

+  [The  internal  or  cochlear  layer  is  merely  apart  of  the  common 
lining  membrane  of  the  labyrinth,  and  is,  most  probably,  a.  fibre-  Natural  size. 

lerous  membrane,  see  p.  681.]  (Section  of  the  tympanum.) 


Fig.  255. 


NEURO1.0GY. 

form,  process  of  anatomists  (n,  fig.  255)  is  nothing  more  than  the  remnant  of  the  hollow 
projection  (x,  fig.  254)  just  described,  one  half  of  which  is  very  thin  and  fragile,  and  is 
sometimes  destroyed  by  long-continued  maceration.  The  so-called  cochleariform  pro- 
cess, therefore,  is  merely  the  reflected  canal  for  the  internal  muscle  of  the  malleus. 

The  Circumference  of  the  Tympanum. — We  shall  examine  this  circumference  above,  be- 
low, in  front,  and  behind. 

Above,  the  tympanum  corresponds  to  the  projection  formed  on  the  anterior  part  of  the 
base  of  the  petrous  portion  of  the  temporal  bone.  In  it  there  is  formed  a  recess,  which 
may  be  named  the  recess  of  the  tympanum,  and  which  is  intended  for  the  reception  of  the 
head  of  the  malleus  {\,fig.  255),  and  the  body  and  posterior  ramus  of  the  incus  (2).  It 
is  thin  and  spongy,  and  is  separated  from  the  squamous  portion  of  the  temporal  bone 
by  a  suture,  which  persists  even  to  the  most  advanced  age.  This  suture  is  traversed  by  a 
great  number  of  canals,  through  which  communicating  vessels  pass  from  those  of  the 
dura  mater  to  those  of  the  tympanum. 

Below,  the  tympanum  is  very  narrow,  and  has  the  form  of  a  trench,  in  which  there  is 
nothing  particular  to  notice.  The  wall  of  the  tympanum  is  here  formed  by  the  osseous 
lamina  of  the  external  meatus. 

At  the  upper  and  back  part  of  the  circumference  of  the  tympanum  is  situated  a  large 
opening  which  leads  into  the  mastoid  cells  (c  c,  figs.  254,  255). 

These  cells  are  extremely  numerous,  and  of  very  unequal  size  ;  they  occupy  the  whole 
of  the  mastoid  portion,  and  the  adjacent  parts  of  the  petrous  portion  of  the  temporal 
bone,  and  are  prolonged  even  above  the  external  meatus.  We  may  therefore  regard 
the  mastoid  portion  of  the  temporal  bone  as  an  appendage  to  the  tympanum.  The  mas- 
toid cells  have  a  very  regular  arrangement  in  the  ox  and  horse,  in  which  animals  they 
are  disposed  in  a  series  radiating  from  the  surface  of  the  mastoid  process  towards  the 
tympanum  ;  their  arrangement  is  much  more  irregular  in  the  human  subject.  Two  large 
cells  are  almost  always  found,  one  near  the  apex,  and  the  other  at  the  posterior  border 
of  the  mastoid  process.  In  one  case  I  found  the  whole  mastoid  process  forming  a  single 
large  cell,  having  extremely  thin  parietes. 

The  mastoid  cells  are  lined  with  a  very  delicate  fibro-mucous  membrane,  which  is  con- 
tinuous with  the  mucous  membrane  of  the  tympanum.  They  contain  air,  and  it  is  only 
in  some  cases  of  disease  that  any  quantity  of  mucus  is  found  in  them. 

The  mastoid  cells  represent,  in  the  auditory  apparatus,  the  cells  and  sinuses  which 
are  connected  with  the  organ  of  smell.  It  may  be  easily  conceived  that  the  intensity  of 
sounds  may  be  increased  by  being  reverberated  from  so  considerable  a  surface. 

In  the  foetus  there  are  no  mastoid  cells  ;  but  there  exists  instead,  in  the  base  of  the 
petrous  portion  of  the  temporal  bone,  a  cavity  prolonged  from  the  recess  already  de- 
scribed in  the  upper  wall  of  the  tympanum,  for  the  ossicula  of  the  ear. 

In  front,  the  tympanum  is  contracted  like  a  funnel,  to  become  continuous  with  the 
Eustachian  tube  (c,  fig.  255) ;  it  might  even  be  said  that  the  tympanum  and  the  Eustachian 
tube  form  together  a  single  funnel-shaped  cavity,  the  expanded  portion  of  which  is  con- 
stituted by  the  tympanum,  and  the  contracted  portion  by  the  tube  of  Eustachius. 

The  canal  for  the  internal  muscle  of  the  malleus  is  formed  in  the  upper  wall  of  the  Eu- 
stachian tube  ;  it  is  a  narrow  tubular  canal  (m),  which,  having  reached  the  anterior  part 
of  the  tympanum,  becomes  applied  to  the  internal  wall  of  that  cavity ;  it  passes  horizon- 
tally backward,  forming  a  projection  upon  this  wall,  and  is  then  reflected  outward,  at  a 
right  angle,  to  form  the  hollow  eminence  already  described.  This  canal  is  separated 
only  by  a  very  thin  osseous  lamina  from  the  Eustachian  tube ;  so  that  the  two  passages, 
placed  one  above  the  other,  have  some  resemblance  to  a  double-barrelled  gun. 

The  Eustachian  Tube. 

The  Eustachian  tube  (more  correctly  called  the  Eustachian  trumpet,  from  tuba,  a 
trumpet,  e,fig.  255),  or  the  guttural  meatus  of  the  ear,  is  a  straight,  funnel-shaped  canal, 
flattened  upon  its  outer  side,  and  about  two  inches  in  length ;  it  extends  from  the  tym- 
panum to  the  upper  and  lateral  part  of  the  pharynx,  where  it  terminates  by  a  free,  ex- 
panded extremity  (wi,  fig.  234),  directed  inward  and  downward,  named  the  guttural  orifice, 
or  the  mouth  of  the  Eustachian  tube.  This  orifice  is  wide  and  dilatable,  of  an  oval  shape, 
the  larger  end  of  the  ovoid  being  turned  upward,  and  being  exceedingly  dilatable  ;  but 
beyond  its  mouth  the  tube  almost  immediately  contracts,  and  will  scarcely  admit  an  or- 
dinary probe.  It  continues  narrow  as  far  as  its  tympanic  orifice,  where  it  again  becomes 
sensibly  dUated.  It  is  directed  obliquely  inward,  forward,  and  downward ;  hence  the 
facility  with  which  the  mucus  of  the  tympanum  flows  into  the  back  of  the  throat. 

The  Eustachian  tube  consists  of  an  osseous  portion  and  of  a  cartilaginous  and  fibrous 
portion. 

The  osseous  portion,  which  is  about  seven  or  eight  lines  in  length,  is  situated  at  the  re- 
treating angle  formed  between  the  squamous  and  petrous  portions  of  the  temporal  bone 

A  triangular  cartilaginous  plate,  formed  into  a  groove,  constitutes  the  inner  half  of  the 
tube  ;  a  fibrous  layer,  which  is  at  first  applied  against  the  circumfiexus  palati  muscle,  and 
is  then  lodged  in  the  groove  between  the  petrous  portion  of  the  temporal  bone  and  the 


THE    OSSICULJlf^OP   THE    EAR.  673 

posterior  border  of  the  sphenoid,  forms  the  external  wall  of  the  canal,  which  is  habitu- 
ally collapsed.  The  base  of  the  triangular  cartilage,  which  forms  the  guttural  orifice  of 
the  tube,  is  notched  in  the  middle,  and  terminates  in  two  thickened  elongated  angles  ;  of 
these,  the  posterior  one,  which  is  more  distinct,  is  movable,  and  may  be  pushed  upward 
and  backward.  The  anterior  angle  is  firmly  fixed  to  the  posterior  margin  of  the  ptery- 
goid process.  As  catheterism  and  injection  of  the  Eustachian  tube  have  become  com- 
mon operations  in  treating  diseases  of  the  ear,  it  is  of  importance  to  define  the  exact 
position  of  its  guttural  orifice  ;  it  is  situated  (m,  fig.  234)  upon  the  side  of  the  pharynx, 
immediately  behind,  and  a  little  above  the  inferior  turbinated  bone. 

The  mucous  membrane  •w\imY\.  lines  the  Eustachian  tube  is  thin,  but  at  the  mouth  of  the 
tube  it  assumes  the  characters  of  the  mucous  membrane  of  the  pharynx  and  of  the  pitui 
tary  membrane,  with  both  of  which  it  is  continuous  ;  it  is  also  continuous  with  the  mu- 
cous membrane  of  the  tympanum  ;  hence  the  close  sympathy  which  exists  between  the 
lining  membrane  of  these  several  parts.* 

The  use  of  the  Eustachian  tube  is  to  renew  the  air  contained  within  the  tympanum , 
but  it  also  gives  exit  to  the  mucous  secretion  of  that  cavity,  t 

Besides  the  orifice  of  the  Eustachian  tube,  and  that  of  the  canal  for  the  internal  mus- 
cle of  the  malleus,  the  anterior  funnel-shaped  part  of  the  circumference  of  the  tympanum 
presents  two  orifices  placed  one  above  the  other  :  the  uppermost  of  these  is  the  internal 
orifice  of  the  canal  for  the  chorda  tympani  nerve  ;  the  lower  one  is  an  oblique  fissure, 
which  transmits  a  fibrous  cord  called  the  anterior  muscle  of  the  malleus.  M.  Huguier  has 
shown  me  a  number  of  preparations  in  which  the  chorda  tympani  nerve  does  not  escape 
through  the  fissure  of  Glasserius,  but  runs  in  a  very  narrow  special  canal,  about  five  or 
six  lines  in  length,  which  is  situated  on  the  inner  side  of  the  Glasserian  fissure,  and 
opens  at  the  base  of  the  scull  in  the  retreating  angle  formed  between  the  squamous  and 
petrous  portions  of  the  temporal  bone,  upon  the  outer  side  of  the  Eustachian  tube,  be- 
hind the  spinous  process  of  the  sphenoid,  and  sometimes  upon  that  bone  itself 

The  fissure  of  Glasserius,  then,  merely  transmits  a  fibrous  bundle,  named  the  anterior 
muscle  of  the  malleus,  and  some  small  arteries  and  veins. 

We  may  now  describe  the  course  of  the  chorda  tympani  nerve. 

In  its  course  this  nerve  passes  through  two  canals,  entering  the  tympanum  by  one,  and 
escaping  from  it  by  the  other.  The  canal  by  which  it  enters  commences  at  the  vertical 
portion  of  the  aqueduct  of  Fallopius,  in  which  the  facial  nerve  is  situated,  passes  upward 
and  forward,  and  opens  immediately  on  the  inner  side  of  the  posterior  margin  of  the 
membrana  tympani,  on  a  level  with  the  horizontal  diameter  of  that  membrane,  and  al- 
most in  the  groove  into  which  it  is  inserted.  Having  entered  the  tympanum  through 
this  canal,  the  chorda  tympani  describes  a  curve,  having  its  concavity  directed  down- 
ward, passfes  between  the  handle  of  the  malleus  and  the  long  ramus  of  the  incus,  enters 
its  proper  canal  upon  the  inner  side  of  the  fissure  of  Glasserius,  and  emerges  at  the  point 
already  mentioned. 

The  Ossicula  of  the  Ear. 

The  tympanum  is  traversed  from  without  inwaM  by  an  osseous  chain,  which  describes 
several  angles,  and  consists  of  four  bones  articulated  with  each  other,  and  extended  from 
the  membrana  tympani  to  the  fenestra  ovalis.  These  little  bones,  forming  the  links  of 
the  chain,  are  named,  from  their  respective  shapes,  the  malleus,  or  Fig.  256. 

hammer  {I,  fig.  256) ;  the  incus,  or  anvil  (2) ;  the  os  orbicular e,  or        ^  a  ^ 

round  bone  (4) ;  and  the  stapes,  or  stirrup  bone  (3) :  the  os  orbicu- 
lare,  however,  appears  to  be  merely  a  tubercle  belonging  to  the 
incus. 

The  Malleus. — The  malleus  {I,  fig.  256)  is  the  most  anterior  of  the  bones  of  the  ear; 
it  is  divided  into  a  head,  a  neck,  and  a  handle,  and  it  has  also  two  processes. 

The  head  of  the  malleus  (a,  fig.  257)  is  situated  in  the  recess  of  the  tympanum,  ir 
front  of  the  incus,  and  above  the  membrana  tympani.  It 
is  ovoid,  and  smooth,  excepting  behind  and  below,  where 
it  is  concave,  in  order  to  be  articulated  with  the  incus. 
Soemmering  has  figured  a  small  fibrous  cord,  which  he 
calls  the  proper  ligament  of  the  malleus,  extending  from 
the  head  of  this  bone  to  the  upper  part  of  the  recess  of 
the  tympanum. 

The  head  is  supported  by  a  constricted  neck  (b),  which 
is  slightly  twisted  and  flattened,  and  serves  also  as  a 
support  for  the  two  processes. 

The  handle  (manubrium,  c)  is  directed  vertically,  and,  Magnified  three  diameters. 

*  [According  to  Dr.  Henl6,  the  mucous  membrane  of  the  Eustachian  tube,  like  that  of  the  upper  part  of  the 
pharynx,  is  covered  with  a  columnar  ciliated  epithelium  ;  but  in  the  tympanum  and  mastoid  cells  the  epithelium 
is  squamous,  and  not  ciliated.] 

t  [The  Eustachian  tube,  by  establishing;  a  communication  between  the  tympanum  and  the  external  air,  en- 
sures an  equal  atmospheric  pressure  on  the  two  surfaces  of  the  membrana  tympani,  so  that  the  necessary  con- 
dition of  that  membrane,  and  of  the  ossicula  auditOs,  as  conductors  of  vibrations,  is  not  interfered  with.] 

4Q 


674  NEUROLOGY. 

with  the  head  and  neck,  forms  a  very  obtuse  angle,  which  retreats  on  the  inner  side ; 
it  is  in  contact  with,  and  adheres  firmly  to  the  internal  surface  of  the  membrana  tyrn- 
pani,  opposite  the  centre  of  which  its  rounded  extremity  is  placed  ;  it  therefore  forms  a 
radius  to  the  circle  represented  by  the  membrana  tympani.  The  lower  part  of  the  handle 
of  the  malleus  is  distinctly  curved,  having  its  concave  side  turned  outward  ;  this  ex- 
plains the  funnel-shaped  depression  upon  the  external  surface  of  the  centre  of  the  mem- 
brana tympani. 

The  processes  of  the  malleus  are  two  in  number :  the  external,  or  short  process  {d),  is 
directed  slightly  outward,  and  rests  against  the  upper  part  of  the  margin  of  the  mem- 
brana tympani,  so  as  to  make  it  project  outward ;  the  other,  or  lo7ig  process,  is  very 
slender  (processus  gracilis  of  Raw,  e),  and  is  shaped  like  a  thorn  (processus  spinosus)  :  rt 
arises  from  the  anterior  part  of  the  neck,  enters  the  Glasserian  fissure,  and  affords  at- 
tachment to  a  muscular  or  fibrous  cord.  I  have  several  times  found  a  simple  ligament- 
ous cord  instead  of  this  process. 

The  Incus. — This  bone  (2,  Jig.  256)  has  been  well  compared  to  a  bicuspid  tooth,  the 
body  of  which  would  be  represented  by  the  body  of  the  incus,  and  the  fangs  by  its  two 
processes. 

The  body  (f,fig.  257)  is  contained  in  the  recess  of  the  tympanum,  behind  the  malleus, 
with  which  it  is  articulated  by  a  very  concave  surface,  directed  forward  and  somewhat 
upward ;  so  that  the  articulation  between  the  head  of  the  malleus  and  the  body  of  the 
incus  is  effected  by  mutual  reception. 

Of  its  two  rami,  the  superior  or  short  one  (g)  is  thick,  conoid,  and  directed  horizontally 
backward :  it  is  situated  upon  the  S£une  plane  as  the  body,  and,  like  it,  is  contained  in 
the  recess  of  the  tympanum,  in  which  it  terminates ;  its  extremity  does  not  appear  to 
me  to  be  free. 

The  inferior,  or  long  ramus  (h),  is  longer  and  thinner  than  the  superior  one  ;  it  passes 
vertically  downward,  parallel  to  the  handle  of  the  malleus,  on  a  plane  internal  and  some- 
what posterior  to  it.  Its  lower  portion  is  bent  into  a  hook,  the  concavity  of  which  is 
turned  inward ;  and  at  its  point  is  formed  a  sort  of  lenticular  and  distinctly  defined  tu- 
bercle (4,  fg.  256  ;  i,  Jig.  257),  which  has  been  regarded  as  a  separate  bone,  and  named 
the  OS  orbiculare,  or  os  lenticulare ;  it  appears  to  me  to  be  merely  a  dependance  of  the  in- 
cus, with  which  I  have  always  found  it  united,  even  in  the  foBtus. 

The  Stapes. — ^The  stapes  (3,  fig.  356),  which  is  shaped  like  a  stirrup,  extends  horizon- 
tally from  the  extremity  of  the  long  process  of  the  incus  to  the  fenestra  ovalis  (see  Jig. 
257),  and  is  situated  upon  a  lower  plane  than  the  rest  of  the  small  bones  of  the  ear. 
Its  head  presents  a  small  articular  cavity,  for  the  reception  of  the  orbicular  tubercle 
of  the  incus.  Its  base  (n)  is  directed  inward,  and  consists  of  a  thin  plate  exactly  corre- 
sponding to  the  fenestra  ovalis,  which  is  rather  accurately  fiUed  up  by  it,  and  to  draw  it 
away  from  which  a  slight  force  is  necessary,  so  that  it  has  a  greater  tendency  to  fall 
into  the  vestibule  than  into  the  cavity  of  the  tjTnpanum.  The  slight  obliquity  of  the 
long  diameter  of  the  fenestra  ovalis  causes  an  inclination  of  the  stapes  in  the  same  di- 
rection. Of  its  two  crura,  or  branches  (fig.  256),  the  anterior  is  the  shorter  and  straight- 
er.  Upon  those  surfaces  of  the  crura  which  are  turned  towards  each  other  there  is 
found  a  groove,  which  appears  to  indicate  the  existence  of  a  membrane  stretched  be- 
tween the  crura.  I  have  found  the  stapes  very  small,  and,  as  it  were,  atrophied.  In 
one  case,  the  two  crura  of  the  stapes  were  united  together. 

Muscles  belonging  to  the  Ossicula  of  the  Ear. 

Most  modem  anatomists  agree  with  Soemmering  in  admitting  four  muscles  for  the 
ossicula  of  the  ear,  viz.,  three  belonging  to  the  malleus,  and  one  to  the  stapes.  The 
incus  has  no  proper  muscle,  because  it  is  merely  an  intermediate  bone  between  the 
malleus  and  the  stapes.  It  is  certain,  however,  that  only  one  of  these  muscles  has  been 
actually  demonstrated,  viz.,  the  internal  muscle  of  the  malleus;  but  it  is  so  easy  to  fall 
into  error  when  examining  such  minute  objects,  that  I  feel  bound  to  suspend  my  judg- 
ment as  to  the  existence  or  non-existence  of  the  other  muscles. 

The  internal  muscle  of  the  malleus,  or  tensor  membrancB  tympani  of  Soemmering  (e,  fig. 
251),  is  an  elongated,  fusiform  muscle,  contained  within  the  bony  canal  formed  in  the 
retreating  angle  of  the  temporal  bone,  above  the  Eustachian  tube,  with  which  it  exactly 
corresponds  in  direction.  It  arises  from  the  cartilaginous  portion  of  the  tube,  from  the 
adjacent  part  of  the  sphenoid  bone,  behind  the  spinous  foramen,  and  from  the  bony  canal 
which  forms  its  sheath.  The  fleshy  fibres  converge  around  a  tendon,  which  appears 
from  among  them,  before  it  passes  out  from  the  bony  canal.  This  tendon  is  reflected  at 
a  right  angle,  like  the  canal  in  which  it  is  contained,  and  then  passes  directly  outward, 
to  be  inserted  into  the  anterior  and  superior  part  of  the  handle  of  the  malleus,  below  the 
processus  gracilis  of  Raw. 

The  muscularity  of  the  band  or  cord  named  the  anterior  muscle  or  ligament  of  the  mal- 
leus, or  the  great  external  muscle  of  Meckel,  is  doubted  by  a  great  number  both  of  pres- 
ent and  former  anatomists.*    I  have  never  seen  anything  more  than  a  fibrous  cord,  which 

"  Fu^re  autem  et  dudum  et  nuper  clari  viri  qui  de  veris  hujus  musculi  fibris  carneis  dubitarunt,  cum 


THE   OSSEOUS   LABYRINTH.  61^ 

cwmmehced  at  the  tip  of  tTie  processus  gracilis  of  the  malleus,  traversed  the  glenoid  fis- 
sure, was  re-enforced  by  other  fibres  arising  from  that  fissure,  and  became  continuous 
with  a  fibrous  layer  arising  from  the  spinous  process  of  the  sphenoid  bone,  and  generally 
regarded  as  the  internal  lateral  ligament  of  the  temporo-maxillary  articulation. 

The  same  remarks  will  also  apply  to  the  small  external  muscle  of  the  malleus,  or  small 
muscle  of  the  malleus  of  Casserius.  This  muscle  is  figured  by  Soemmering,  who  says 
that  he  found  it  exceedingly  developed  in  one  subject.  All  that  I  have  clearly  seen  is  a 
cylindrical  cord,  extending  from  the  upper  part  of  the  frame  of  the  membrana  tympani 
to  the  short  process  of  the  malleus,  or,  rather,  below  it,  according  to  the  observations  of 
Scemmering  {ad  manubrium  mallei,  infra  brevem  ejus  processum).  This  small  muscle 
would  relax  the  membrana  t3TTipani ;  hence  it  has  been  named  by  Soemmering  the  lax- 
ater  membrance  tympani. 

The  muscle  of  the  stapes,  or  stapedius  muscle  (o,  fig.  255),  which  is  the  smallest  in  the 
body,  has,  since  the  time  of  Varolius,  by  whom  it  was  discovered,  been  regarded  as  a 
ligament  by  some  anatomists  ;  nevertheless,  it  is  more  generally  admitted  to  be  muscu- 
lar than  that  last  described.  It  arises  from  some  part  of  the  interior  of  the  pyramid,  and, 
escaping  from  that  process,  passes  forward,  and  terminates  at  the  back  of  the  neck,  or 
constricted  part  of  the  head  of  the  stapes,  behind  its  articulation  with  the  incus.  Soem- 
mering has  not  only  represented  its  fleshy  belly  and  its  tendon,  but  also  (see  fig.  20,  tab. 
11)  a  filament  of  the  facial  nerve  terminating  in  it.  It  is  difficult  to  conceive  that  such 
a  serious  mistake  should  have  been  committed  by  this  great  anatomist.  I  have  exam- 
ined this  cord  under  a  lens,  and  have  never  been  able  to  discover  any  muscular  fibres  in 
it.  We  do  not  conceive  how  a  muscle  should  exist  in  so  delicate  a  cord.  Supposing, 
however,  that  it  does  exist,  it  must  move  the  stapes  in  such  a  way  that  the  posterior  ex- 
tremity of  the  base  of  that  bone  would  be  pushed  into  the  fenestra  ovalis,  while  the  an- 
terior extremity  would  be  carried  outward. 

Movements  of  the  Ossicula. — The  chain  of  small  bones  in  the  ear  is  so  arranged,  that 
any  movement  of  one  of  its  extremities  is  communicated  to  the  entire  chain.  Their  mo- 
tion is  precisely  similar  to  that  of  a  bell-crank.  M.  Huguier  is  incUned  to  believe  that 
the  processus  gracilis  of  Raw  serves  as  a  fulcrum,  around  which  the  malleus  performs 
a  rotatory  movement,  the  effects  of  which  are  transmitted  to  the  stapes  through  the  in- 
cus. The  contraction  of  the  internal  muscle  of  the  malleus,  or  tensor  membranae  tym- 
pani, must  draw  the  handle  of  the  malleus  inward  and  its  head  outward  ;  the  incus,  from 
its  firm  connexion  with  the  head  of  the  malleus,  follows  that  bone,  and  as  it  swings  upon 
its  short  horizontal  process,  its  vertical  process  is  carried  inward,  and  therefore  presses 
the  stapes  into  the  fenestra  ovalis. 

The  Lining  Membrane  of  the  Tympanum. 

The  tympanum  is  lined  by  a  very  thin  membrane,  which  not  only  covers  the  walls  of 
this  cavity,  but  also  forms  a  very  evident  investment  for  the  ossicula,  and  is,  moreover, 
prolonged  into  the  mastoid  cells,  lining  them  throughout,  and  forming  small  duplicatures 
around  the  vessels  by  which  some  of  the  cells  are  traversed.  This  membrane  is  con- 
tinuous with  the  mucQus  membrane  of  the  Eustachian  tube,  and  therefore  indirectly 
with  that  of  the  pharynx.* 

It  serves  at  once  as  an  internal  lining  for  the  tympanum,  and  a  periosteum  for  the  os- 
seous walls  of  that  cavity,  and  should  therefore  be  regarded  as  a  fibro-mucous  membrane. 
It  secretes  a  mucus,  which  in  the  natural  state  simply  moistens  its  surface,  but  in  some 
cases  of  disease  occupies  the  whole  cavity.  The  catarrhal  character  of  the  products  ol 
suppuration  in  the  tympanum,  the  continuity  of  this  lining  membrane  with  the  mucous 
membrane  of  the  pharynx,  and  its  extreme  vascularity,  leave  no  doubt  of  its  being  a  mu 
cous  membrane. 

The  Internal  Ear,  or  Labyrinth. 
The  internal  ear,  or  labyrinth  (f,fig.  251),  the  deep-rooted  and  essential  portion  of  the 
organ  of  hearing,  is  situated  on  the  inner  side  of  the  tympanum,  in  the  substance  of  the 
petrous  portion  of  the  temporal  bone.  It  consists  of  the  osseous  labyrinth,  which  forms 
a  receptacle  for  the  membranmis  labyrinth,  which  is  the  immediate  seat  of  the  sense  of 
hearing.  No  part  of  the  body  has  a  more  conlplex  and  delicate  structure.  The  labyr 
inth  is  composed  of  three  very  distinct  compartments,  which  have  been  named  the  ves 
tibule,  the  semicircular  canals,  and  the  cochlea. 

The  Osseous  Labyrinth. 
Preparation. — This  is  justly  regarded  as  one  of  the  most  difficult  dissections,  even 
when  the  parts  are  previously  known.     The  dissection  should  be  made  upon  temporal 
bones  from  subjects  of  different  ages,  upon  bones  that  have  been  macerated,  upon  oth- 
ers that  have  been  dried  without  maceration,  and  also  upon  bones  in  the  fresh  state. 

inultam  quidem  membranam  a  periosteo  propa^atam,  sulcuin  maxillje  repleri  viderent,  et  processui  longissimo 
circumnasci,  esEterum  in  eo  carneam  naturam  non  deprehenderent.  Neque  mea  erperimenta  remexpediunt 
Musculum  quoties  volui,  ostendi,  num  veras  fibras  viderem,  plerumqiie  dub^us  hxsi."— (Holier,  torn,  v  ,  lib 
TV.,  p.  218.)  ■  ■  *  See  note,  p.  673. 


676 


NEUROLOGY. 


Commence  with  a  foetal  temporal  bone,  in  which  the  labyrinth  can  very  easily  be  isola- 
ted, in  consequence  of  its  being  surrounded  only  by  a  spongy  texture,  readily  yielding  to 
the  knife.  In  the  adult,  the  labyrinth  is,  in  proportion,  much  less  developed  than  in  the 
foetus,  and  is  surrounded  with  so  compact  a  tissue,  that,  in  order  to  cut  it,  it  is  necessa- 
ry to  use  a  chisel,  a  file,  or  a  very  strong  scalpel.  It  is  important  to  have  a  great  num- 
ber of  temporal  bones,  so  as  to  be  able  to  make  several  different  sections. 

Preparation  of  the  Vestibule. — Open  the  vestibule  through  its  upper  wall,  which  corre- 
sponds to  the  upper  surface  of  the  petrous  portion  of  the  temporal  bone,  opposite  the  fe- 
nestra ovalis,  between  the  superior  vertical  semicircular  canal  and  the  internal  auditory 
meatus. 

Preparation  of  the  Semicircular  Canals. — In  the  foetus,  one  of  the  semicircular  canals 
projects  upon  the  base  of  the  petrous  portion  of  the  temporal  bone  ;  it  is  easy  to  isolate 
it,  as  well  as  the  other  canals,  by  removing,  with  a  strong  scalpel,  the  spongy  tissue  in 
which  they  are  imbedded.  It  is  useful  to  have  two  preparations  of  the  semicircular  ca- 
nals ;  one  in  which  the  canals  remain  entire,  and  another  in  which  they  have  been  opened. 

Preparation  of  the  Cochlea. — Remove  layer  by  layer  that  part  of  the  petrous  portion  of 
the  temporal  bone  which  corresponds  to  the  bottom  of  the  internal  auditory  meatus.  A 
layer  of  very  thin  spongy  tissue  shows,  in  the  foetus,  that  we  have  arrived  at  the  coch- 
lea ;  remove  this  spongy  tissue  with  care,  and  expose  the  cochlea,  both  on  its  upper  and 
lower  surfaces.  In  one  preparation,  the  cochlea  should  be  merely  isolated  ;  in  another, 
it  should  be  carefully  opened,  and  for  this  purpose  it  is  sufficient  to  make  a  simple  cut 
into  each  of  its  turns  :  it  is  of  importance  not  to  remove  the  summit  of  the  cochlea. 

The  Vestibule. 
If  a  probe  be  passed  from  the  tympanum  through  the  fenestra  ovalis  {f,fig.  258),  it 
P^    25g  enters  an  ovoid  cavity  (a  b  t,  fig.  259)  called  the 

vestibule. 

The  vestible  is  the  centre  of  the  internal  ear, 
and  forms  an  intermediate  cavity  or  passage  (fo- 
rum fodinaj  metallicas,  Vesalius)  between  the 
semicircular  canals  {op  q,fig.  258),  which  are  on 
its  outer  side,  and  the  cochlea  (Z),  which  is  to  its 
inner  side.  It  is  situated  in  a  line  with  the  axis 
P^  of  the  internal  auditory  meatus.  It  is  remark- 
able for  having  a  great  number  of  both  large  and 
small  openings  into  it. 
The  large  openings  are  seven  in  number:  the  first  is  the  fenestra  ovalis  {ffigs.  258, 
261),  which  would  establish  a  free  communication  between  the  vestibule  of  the  tympa- 
num if  it  were  not  for  the  base  of  the  stapes,  which  closes  it  hermetically,  as  we  may 
be  convinced  by  examining  it  from  the  vestibule,  when  the  stapes  remains  in  its  plac  ♦ 
There  are  five  openings  (o' p'  q',fig.  259  ;  o'  a',  fig.  261)  for  the  three  semicircular  canals  ; 
yi„.  259.  and  the  seventh  is  the  orifice  (/)  of  the  vestibular 

scala  of  the  cochlea.  In  macerated  bones  we 
find,  besides,  an  eighth  opening,  situated  below 
the  fenestra  ovalis,  having  an  oblong  shape,  and 
leading  into  the  highest  part  of  the  fenestra  ro- 
tunda. 

Of  the  small  openings,  the  first  is  the  orifice  (r, 
fig.  259)  of  the  aqueduct  of  the  vestibule,  which 
opens  upon  the  posterior  wall  of  this  cavity  to 
the  inner  side  of  the  common  opening  for  the  two 

„ ,  ^.  .V  ..V  w.   ,,  vertical  semicircular  canals  (i.  e.,  in  the  recessus 

^XgJ^^'Co-iumeTer,"'"  sulciformis).    The  aqueduct  of  the  vestibule  turns 

a  short  distance  around  that  common  opening,  and  then,  bending  at  a  right  angle,  ter- 
minates upon  the  posterior  surface  of  the  petrous  portion  of  the  temporal  bone  by  an 
orifice  already  described  (see  Osteology).  The  other  small  openmgs  m  the  vestibule 
are  foramina  for  the  passage  of  vessels  and  nerves  ;  they  form  the  macula  cribrosa,  which 
corresponds  with  the  bottom  of  the  internal  auditory  meatus. 

The  character  of  the  vestibule  is  irregularly  ovoid,  and  is  divided  by  a  cn»ta  into  two 
fossae  :  one  inferior  and  hemispherical,  named  the  fovea  hemispherica  {a,  fig.  259) ;  the 
other,  superior  and  semi-elliptical,  called  the  fovea  semi-elliptica  (h).  Morgagni  has  de- 
scribed a  third  groove-like  fossa  {recessus  sulciformis),  situated  at  the  mouth  of  the  com- 
mon orifice  of  the  two  superior  semicircular  canals. 

The  Semicircular  Canals. 
The  semicircular  canals,  three  in  number,  represent  three  cylinders  or  tubes  (tubaeformes 
canales,  Simmering),  of  equal  diameters,  and  curved  very  regularly,  so  as  to  describe 

*  CThe  base  of  the  stapes  is  retained  in  its  situation,  and  the  complete  closure  of  the  fenestra  ovalis  is  ef- 
fected, by  the  reflection  of  the  lining  membrane  of  the  tympanum  on  the  one  hand,  and  by  that  of  the  bning 
membrane  of  the  labyrinth  on  the  other.] 


THE    COCHLEA.  677 

portions  of  circles  ;  they  are  situated  within  the  substance  of  the  base  of  the  petrous 
portion  of  the  temporal  bone,  behind  the  vestibule,  into  which  they  open  by  the  five  ori- 
fices already  described. 

They  have  been  named  the  great,  the  middle,  and  the  small  semicircular  canals  ;  terms 
which  have  caused  much  confusion,  because  the  differences  between  them,  in  regard  to 
length,  are  not  alone  sufficient  to  distinguish  them  from  each  other. 

Their  direction  forms  a  much  better  ground  of  distinction  between  them.  Two  are 
vertical,  and  one  is  horizontal :  there  is  an  anterior  and  superior  vertical,  and  a  posterior 
and  inferior  vertical  canal ;  the  horizontal  canal  is  external,  and  is  situated  between  the 
two  others.  ,  .  ^ 

Tlie  superior  vertical  canal  (p,  figs.  258,  260),  which  describes  two  thirds  of  a  circle,  is 
placed  at  the  highest  part  of  the  labyrinth,  immediately  to  the  outer  side  of  the  vestibule. 
A  plane  passing  through  the  two  branches  of  this  canal  would  cut  the  base  of  the  petrous 
portion  almost  at  a  right  angle. 

The  convexity  of  this  canal  is  turned  upward,  and  its  concavity  downward.  In  the 
foetus,  its  concavity  is  free,  so  that  it  can  be  seen  without  any  dissection ;  but  in  the 
adult  it  is  filled  up  with  osseous  tissue. 

The  anterior  and  outer  extremity  {f,figs.  258,  259)  of  this  canal  is  dilated  into  an 
ampulla,  and  opens  separately  at  the  upper  and  outer  part  of  the  vestibule.  The  poste- 
rior and  inner  extremity  unites  with  the  corresponding  extremity  of  the  inferior  vertical 
canal  to  form  a  common  canal  (a,  fig.  260),  which  opens  without  any  dilatation  into  the 
upper  and  inner  part  of  the  vestibule  {a',  fig.  261).  Fig.  260 

The  inferior  vertical  canal  {q,  figs.  258,  260)  is 
placed  at  right  angles  to  the  preceding,  and  par- 
allel with  the  posterior  surface  of  the  petrous 
portion.  It  commences  at  the  inner  and  upper 
part  of  the  vestibule,  by  the  common  canal  (a, 
fig.  260)  already  described,  passes  almost  di- 
rectly outward,  curves  at  first  downward,  and 
then  forward,  and  becomes  dilated  into  an  am- 
pulla {q',  fig.  258)  near  the  vestibule,  into  which 
cavity  it  opens  {q',  fig.  259),  about  the  distance 
of  a  line  from  the  point  at  which  it  commences. 
This  canal,  therefore,  describes  nearly  a  com- 
plete circle  ;  and  hence  the  term  canalis  major 
et  longior,  still  given  to  it  by  Soemmering,  in 
contradistinction  to  the  superior  vertical  semi- 
circular canal,  which  he  calls  minor  et  brevior. 

The  horizontal  canal  (o,  figs.  258,  260),  canalis 
minimus,  brevissimus,  sive  exterior  of  Soemmer-  fc;*^ji_ 
ing,  commences  in  the  vestibule  {o',figs.  258, 
259)  between  the  fenestra  ovalis,  which  is  be- 
low, and  the  ampullar  opening  of  the  superior  vertical  canal,  which  is  ahove  ;  it  becomes 
dilated  into  an  ampulla,  describes  a  horizontal  curve  having  its  convexity  turned  out- 
ward, and  opens  {o',fig.  261)  upon  the  inner  wall  of  the  vestibule,  between  the  common 
opening  (a')  of  the  two  vertical  canals  and  the  proper  opening  ({'')  of  the  inferior  vertical 
canal. 

It  appears,  then,  that  each  of  the  three  semicircular  canals  has  one  of  its  extremities 
dilated  into  an  ampulla,  and  the  other  not  dilated  ;  that  the  two  vertical  canals  unite  by 
their  non-dilated  extremities  ;  that  of  the  five  openings  belonging  to  the  semicircular 
canals,  two  occupy  the  outer,  and  three  the  inner  wall  of  the  vestibule,  and  that  the  three 
last  consist  of  the  common  canal  formed  by  the  two  vertical  canals,  by  the  ampullar  ex- 
tremity of  the  posterior  vertical  canal,  and  by  the  non-ampuUar  extremity  of  the  horizon- 
t£il  canal. 

The  Cochlea. 

The  cochlea  {I,  fig.  258),  or  snail,  so  called  from  its  resemblance  to  the  shell  of  that 
molluscous  animal,  may  be  said  to  consist  of  a  conoid  tube,  which  is  subdivided  into 
two  cavities,  called  scales,  by  a  septum  extending  from  its  base  to  its  apex,  and  is  coiled 
upon  itself  into  a  spiral  containing  two  turns  and  a  half 

The  cochlea  is  the  most  anterior  part  of  the  internal  ear ;  it  is  situated  on  the  inner 
side,  and  in  front  of  the  tympanum  ;  its  base  {d,  fig.  260)  rests  upon  the  bottom  of  the 
internal  auditory  meatus.* 

Its  external  surface  is  blended,  in  the  adult,  with  the  substance  of  the  petrous  portion 
of  the  temporal  bone,  so  that  it  requires  much  skill  to  carve  it  out  vnthout  breaking  into 
its  cavity  :  in  the  foetus,  on  the  contrary,  such  a  dissection  is  extremely  easy,  on  ac- 
count of  the  thin  layer  of  spongy  osseous  tissue  by  which  it  is  separated  from  the  rest 
of  the  bone. 

*  [The  summit  of  the  cochlea  is  directed  forward,  downward,  and  outward.  The  gyri  of  the  cochlea  are 
soiled  in  a  direction  from  below  upward,  a"'  ''""ti  without  inward.] 


C78 


NEUROLOGY. 


The  following  parts  of  the  cochlea  are  separately  described  :  the  tube  of  the  cochlea  or 
lamina  gyrorum,  the  lamina  spiralis,  the  axis  or  columella,  the  two  scala,  and  the  aqueduct. 
The  Tube  of  the  Cochlea. — The  tube  of  the  cochlea  {canalis  spiralis  cochlce,  or  lamina  gy- 
rorum) is  the  compact  lamina  (l,  figs.  258,  262)  which  forms  the  external  walls  of  the 
cochlea.  If  we  imagine  a  hollow  osseous  cone,  coiled  spirally,  cicut  circa  fulcrum  convol- 
vulus {Holler),  or  like  a  winding  staircase  ;  and  farther,  that  the  lowest  turn  of  the  spire 
embraces  the  turn  above  it,  and  that  the  walls  of  the  different  turns  are  blended  with 
each  other,  we  shall  have  a  correct  idea  of  the  tube  of  the  cochlea :  as  before  stated,  the 
spire  thus  formed  describes  two  turns  and  a  half 

The  Spiral  Lamina  of  the  Cochlea. — The  spiral  canal,  or  tube  of  the  cochlea,  is  subdi- 
vided lengthwise  into  two  secondary  cavities  (c  e,  c  e,  figs.  263,  264),  called  scala.  {scala,  a 
staircase),  by  a  septum  (a),  which  is  named  the  spiral  lamina  of  the  cochlea  {lamina  spi- 
ralis cochlea). 

Commencing  at  the  base  of  the  cochlea  {t,  fig.  259  ;  also  fig.  263),  and  at  the  fenestra 
rotunda,  where  it  can  be  very  easily  seen,  the  spiral  lamina  winds  edgewise  around  the 
axis  or  columella  {b  b,  fig.  262),  and  is  continued  without  any  interruption  to  the  summit 
or  cupola  (/)  of  the  cochlea,  the  several  turns  of  which  it  exactly  follows.  Its  internal 
border  is  applied  against  the  axis  of  the  cochlea,  and  adheres  intimately  to  it,  excepting 
above,  where  it  is  free  for  a  short  distance,  and  leaves  a  communication  {n,  fig.  263)  be- 
tween the  two  scalae.  Mar  go  liber  lamina  spiralis  quo  fit  ut  utriusque  scala.  sit  communica- 
tio  {Sammering).  Its  external  border  adheres  to  the  inner  surface  of  the  lamina  gyrorum, 
or  tube  of  the  cochlea.  In  consequence  of  the  conical  form  of  this  tube,  the  lamina  spi- 
ralis would,  if  unrolled,  represent  an  isosceles  triangle,  the  base  of  which  had  corre- 
sponded to  the  fenestra  rotunda,  and  the  apex  to  the  summit  of  the  cochlea. 

The  spiral  lamina  consists  of  two  portions — an  internal  osseous  and  an  external  mem- 
branous portion.* 

The  osseous  portion  {lamina  spiralis  ossea,  d,  figs.  259,  261,  262,  264)  predominates  in 
the  first  turn,  diminishes  gradually  in  the  second,  and 
ceases  at  the  commencement  of  the  third,  where  it  termi- 
nates in  a  kind  of  hook  or  beak  {hamulus  vel  rostrum,  e,fig. 
262).  This  bony  portion  is  thick,  and  consists  of  two  la- 
mellae, between  which  are  found  a  great  number  of  very 
delicate  canals,  through  which  the  nerves  of  the  cochlea 
v  pass.  These  two  lamellae  form  two  distinct  furrows  upon 
1^'  the  columella. 

The  membranous  portion  {lamina  spiralis  membranacea, 
a  a,  figs.  263  to  265)  completes  the  septum,  forming  its 
Cochlea  (dry)  magnified  four  times.       ^y^gj.  ^^^      J^  jg  narrow  in  the  first  tum  of  the  cochlea, 

becomes  broader  in  the  second,  and  constitutes  the  entire  septum  in  the  third 


Fig.  263. 


Cochlea  ( 


The  bony  and  membranous  portions  of  the  spiral  lamina, 
therefore,  represent  two  isosceles  triangles,  so  arranged 
that  the  base  of  the  one  corresponds  to  the  apex  of  the 
other,  and  vice  versa. 

Moreover,  as  Comparetti  remarks,  three  zones  can  be 
distinguished  in  the  membranous  portion  of  the  spiral  lam- 
ina, the  consistence  of  which  diminishes  progressively 
■/  from  the  margin  of  the  osseous  lamina  towards  the  inter- 
nal surface  of  the  tube  of  the  cochlea. 

The  Axis  or  Columella  of  the  Cochlea. — From  the  bottom,  or, 
rather,  from  the  posterior  part  {d,  fig.  260)  of  the  bottom  of 
the  internal  auditory  meatus,  arises  a  bony  process,  which  is  directed  almost  horizontally 
outward ;  it  occupies  the  centre  or  axis  of  the  cochlea,  and  around  it  both  the  tube  and 
spiral  lamina  describe  their  several  turns.  This  bony  process  is  called  the  axis  of  the 
cochlea,  columella,  modiolus,  or  nucleus  {b,  figs.  262,  264).  It  extends  from  the  base  to  the 
summit  of  the  cochlea,  but  undergoes  certain  changes  during  its  course.  Opposite  the 
first  turn  it  is  extremely  thick,  but  becomes  much  thinner  in  the  first  half  of  the  second 
tum.  In  the  second  half  of  the  second  turn,  and  in  the  last  half  turn,  it  is  replaced  by  a 
cup-shaped  lamella,  called  the  infundibulum  (scyphus,  Vieussens,  c,  fig.  262),  the  expand- 
ed portion  of  which  is  turned  towards  the  cupola  (/)  of  the  cochlea.  The  modiolus  or 
axis  of  the  cochlea,  then,  has  three  perfectly  distinct  parts. 

The  base  of  the  modiolus,  which  is  seen  at  the  bottom  of  the  auditory  meatus,  is  marked 
by  a  very  distinct  spiral  tract  {d,  fig.  260),  perforated  with  foramina,  through  which  the 
filaments  of  the  auditory  nerve  are  transmitted.  It  is  the  tractus  spiralis  foraminulentus 
of  Cotugno. 

The  apex  of  the  modiolus,  when  examined  in  a  cochlea  which  has  been  opened  from 
the  under  surface  of  the  petrous  portion  of  the  temporal  bone,  presents  a  decidedly  in- 
fundibuliform  figure.     But  in  a  cochlea  which  has  been  opened  from  its  upper  surface 


*  [In  the  dried  cochlea  [fig.  262),  the  two  seals  communicate  along  their  whole  course.] 


THE  COCHLEA.  679 

ifig.  264),  on  the  contrary,  it  has  the  appearance  of  a  very  slender  stalk,  continuous  with 
the  rest  of  the  modiolus,  and  proceeding  directly  to  the  cupola  of  the  cochlea.  This  two- 
fold structure  depends  upon  the  fact  that  the  terminal  lamella  of  the  modiolus  forms  only 
half  a  funnel,  which  half  is  turned  towards  the  lower  half  of  the  cochlea.  ,  This  terminal 
lamella  of  the  modiolus,  which  has  been  very  well  described  by  Huguier,  is  of  a  triangular 
form,  extends  through  half  a  turn  of  a  spiral,  and  adheres  to  the  inner  surface  of  the 
tube  of  the  cochlea  by  its  external  convex  border.  Its  internal  border  or  margin  is  straight 
and  free,  and  is  the  only  part  of  this  lamella  which  is  seen  when  the  cochlea  is  opened 
from  above,  while  its  convex  border  and  its  surfaces  are  distinctly  seen  when  the  coch- 
lea is  opened  from  below.  The  hamulus  (e,  fig.  262)  of  the  osseous  portion  of  the  lamina 
spirahs  terminates  opposite  the  middle  of  this  free  border  or  margin. 

The  surface  of  the  modiolus  is  marked  like  a  screw  by  two  furrows  correspondmg 
to  the  two  lamellae  of  the  osseous  part  of  the  spiral  lamina ;  this  surface  is  pierced  with 
foramina  for  the  branches  of  the  auditory  nerve. 

If  the  modiolus  be  divided  longitudinally  (fig.  264),  it  wDl  be  seen  that  its  centre  is 
traversed  by  a  number  of  canals,  for  the  passage  of  the  branches  pig.  264. 

of  the  auditory  nerve.  These  canals  open  by  the  foramina  on 
its  surface.  In  the  centre  of  the  half  funnel  formed  by  the  ter- 
milial  lamella  of  the  modiolus  is  an  opening,  through  which  the 
terminal  filament  of  the  cochlear  branch  of  the  auditory  nerve 
passes  out ;  it  is  the  orifice  of  the  tubulus  centralis  modioli. 

The  Scarce  of  the  Cochlea. — The  spiral  lamina  {d  d,  fig.  264)  di- 
vides the  cavity  of  the  tube  of  tne  cochlea  into  two  secondary 
cavities  (c  e,  c  e),  called  the  scala  of  the  cochlea.  They  are  dis- 
tinguished as  the  external,  superior,  or  vestibular  scaia  (scala  ves- 
tibuli,  c  c,  figs.  263,  264),  and  the  internal,  inferior,  or  tympanic 
scala  (scala  tympani,  e  e).    The  first  (c  c,  fig.  265)  communicates  ^ 

directly  with  the  vestibule  (between  t  and  s) ;  the  second,  which  Coehiea  magnified. 

commences  at  the  fenestra  rotunda  (s,  fig.  258),  would  communicate  with  the  tympanum 
if  that  fenestra  were  not  closed  by  a  membrane  ;  hence  the  term  scala  clausa.  The 
tympanic  scala  is  decidedly  larger  than  the  vestibular.  The  section  of  either  of  the  scalae, 
at  right  angles  to  its  axis,  is  semicircular. 

The  two  scalae  conununicate  near  the  summit  of  the  cochlea  (at  n,  figs.  263, 265).  Both 
the  situation  and  nature  of  this  communication  can  be  easily  eiscertained,  and  have  been 
well  described  by  Soenomering,  and  more  recently  by  MM.  Breschet  and  Huguier. 

The  lamina  spirahs,  which,  we  have  seen,  adheres  closely  to  the  modiolus,  continues 
to  wind  spirally  around  the  half-funnel-shaped  termination  of  the  modiolus,  but  when  it 
arrives  opposite  the  concavity  of  this  half  funnel,  it  ceases  to  be  attached  to  that  con- 
cavity, its  internal  border  becomes  free,  and  is  then  continued  on  to  the  inner  surface  of 
the  summit  of  the  cochlea.  It  follows,  therefore,  that  the  free  concave  border  of  the 
lamina  spiralis  is  opposite  to  the  concavity  of  the  infundibulum  ;  and  hence  there  is  an 
interruption  in  the  septum,  in  the  form  of  a  circular  opening,  the  canalis  scalarum  commu- 
nis of  Cassebohm,  the  helicotrema  of  Breschet  {n,figs.  263,  265),  which  establishes  a  com- 
munication between  the  two  scalae  :  moreover,  this  opening  is  not  situated  precisely  at 
the  summit  of  the  scalae,  but  a  little  below  that  point ;  nor  is  the  opening  of  communica- 
tion (between  t  and  s,  fig.  265)  between  the  vestibular  scala  and  the  vestibule  situated  at 
the  lowest  part  of  that  scala. 

The  Aqueduct  of  the  Cochlea. — The  aqueduct  of  the  cochlea  opens  at  one  end  {n,fig.  259) 
into  the  tympanic  scala  of  the  cochlea,  near  the  fenestra  rotunda ;  and  at  the  other,  by  an 
expanded  extremity,  upon  the  lower  border  of  the  petrous  portion  of  the  temporal  bone, 
near  the  jugular  fossa.  It  does  not  appear  to  have  any  such  use  as  was  attributed  to  it 
by  Cotugno.  Like  the  aqueduct  of  the  vestibule,  it  is  merely  a  canal  for  a  vessel,  and 
as  such  was  denominated  by  Wildberg  canalis  vcnosus  cochlea.  The  liquor  Cotunnii 
could  not  pass  through  this  canal,  for  it  is  closed  by  the  dura  mater.  Ilg  has  taken  a 
very  ingenious  view  of  the  structure  of  the  modiolus  and  cochlea.  According  to  that 
author,  the  modiolus  is  not  an  osseous  centre  independent  of  the  lamina  gyrorum,  but 
rather  the  internal  wall  of  the  spiral  tube  of  the  cochlea,  which,  in  describing  its  first 
turn,  intercepts  a  considerable  cylindrical  space  of  about  two  lines  and  a  half  in  diam- 
eter, and  then  a  smaller,  but  still  cylindrical  space,  of  about  half  a  line  in  diameter,  in 
its  second  turn ;  while  in  the  third  turn  there  is  no  space,  and  therefore  the  axis  or 
modiolus  is  wanting,  but  it  is  replaced  by  the  internal  wall  of  the  spiral  tube  of  the 
cochlea  itself  The  terminal  lamella  of  the  modiolus  would  therefore  be  formed  by  the 
internal  wall  of  the  spiral  tube. 

This  view  is  supported  by  the  structure  of  the  bottom  of  the  internal  auditory  meatus, 
on  which  is  found  a  turn  and  a  half  of  a  spiral  groove,  precisely  corresponding  to  the 
spire  of  the  cochlea,  and  by  sections  of  the  cochlea  made  after  Scemmering's  plan,  from 
the  apex  to  the  base.     {Vide figs.  11,  12,  13,  14,  15,  of  Scemmering's  fourth  plate.) 

The  Membranous  Labyrinth. 

The  membranous  labyrinth,  discovered  by  Conipannti  and  .Scarpa,  ha.s  been  correctly 


NEUROLOGY. 

described  and  figured  by  Soemmering.  M.  Breschet  has  recently  enriched  our  knowl- 
edge of  this  intricate  anatomical  subject  with  many  most  interesting  facts.  {Etudes 
anatomiques  et  physiologiques  sur  Vorgane  de  Vouie  et  sur  V audition  dans  Vhomme  et  Us  ani- 
maux  vertebres,  1833.) 

It  is  useless  to  attempt  the  examination  of  the  membranous  labyrinth  in  the  human 
subject  without  some  previous  preparation.  If  the  labyrinth  be  opened,  it  is  found  to 
contain  a  fluid ;  the  eye  can  detect  nothing  else.  By  previously  macerating  it  in  diluted 
nitric  acid,  the  twofold  advantage  is  gained  of  softening  the  bones,  so  that  they  can  be 
cut  with  a  scalpel,  and  of  hardening  and  rendering  opaque  the  nervous  tissues.  Before 
studying  the  membranous  labyrinth  in  the  human  subject,  it  should  first  be  examined  in 
the  large  cartilaginous  fishes,  such  as  the  ray  and  the  turbot,  in  which  it  is  most  highly 
developed.  It  is  then  seen  that  the  semicircular  canals  and  the  vestibule  contain,  be- 
sides a  fluid,  certain  semi-transparent  membranous  tubes  and  sacs,  the  aspect  of  which 
closely  resembles  that  of  the  retina. 
The  membranous  labyrinth  (fig.  265)  is  not  so  extensive  as  the  osseous  labyrinth : 
thus,  it  does  not  enter  the  cochlea,  and  its  diameter  is 
much  less  than  that  of  the  bony  labyrinth.  It  scarcely 
occupies  one  half  the  cavity  of  the  latter. 

The  space  between  the  bony  and  membranous  lab- 
yrinths is  filled  with  a  limpid  fluid,  named,  after  Co- 
tugno,  the  liquor  Cotunnii,  although  it  had  been  no- 
ticed by  several  anatomists  before  that  author.  (De 
aqua  ductibus  auris  human<B  inierna.  Cotugno,  1760.) 
It  is  the  perilymph  of  M.  Breschet. 
There  is  no  air  in  the  labyrinth,  and  it  is  somewhat 
Membranous  labyrinth  (leftside).  singular  that  SO  accuratc  an  anatomist  as  M.  Ribes 

should  have  recently  defended  a  contrary  opinion,  although  it  has  been  repeatedly  refuted. 
The  membranous  labyrinth  is  itself  filled  with  a  fluid  which  was  correctly  described 
by  Scarpa,  and  which  might  be  named  X\\e  fluid  of  Scarpa.  M.  de  Blainville  has  com- 
pared it  to  the  vitreous  humour  of  the  eye,  and  has  named  it  la  vitrinc  auditive :  it  is  the 
endo-lymph  of  M.  Breschet. 

The  membranous  labyrinth  consists  of  membranous  semicircular  canals,  and  of  a  ves- 
tibular portion. 

The  Membranous  Semicircidar  Canals. 

The  membranous  semicircular  canals  {op  q,fig.  265)  were  regarded  as  nervous  cords  by 
Scarpa,  who  first  described  them  ;  they  have  precisely  the  same  form  as  the  osseous 
semicircular  canals,  although  they  do  not  completely  fill  them.  Soemmering  improperly 
calls  them  tubuli  membrano-cartilaginosi.  Each  membranous  canal,  like  the  corresponding 
osseous  one,  has  its  ampulla,  or  ovoid  muscle  {o'  p'  q'). 

The  two  vertical  membranous  canals  unite  at  one  end  into  a  common  canal,  and, 
therefijre,  the  three  membranous  semicircular  canals,  like  their  osseous  investments, 
open  into  the  membranous  vestibule  by  five  distinct  orifices. 

The  membranous  vestibule  consists  of  two  very  distinct  parts,  the  common  sinus  and  the 
saccule. 

The  sinus  communis  vestibuli,  or  vestibular  utricle  (u),*  as  was  first  shown  by  Scarpa, 
forms  the  confluence  of  the  membranous  semicircular  canals  which  open  into  it  by  five 
orifices.  The  utricle  is  situated  in  the  fovea  semi-elliptica  of  the  vestibule,  and  floats, 
as  it  were,  in  the  liquid  of  Cotugno  ;  it  is  distended  by  the  liquid  of  Scarpa,  so  as  to  re- 
semble an  oblong  bulla.  The  liquid  of  Cotugno  separates  it  from  the  base  of  the  stapes, 
as  Scarpa  very  well  pointed  out. 

The  sacculus  vestibuli,  or  vestibular  saccule  (sacculas  proprius  sphaericus,  Soemmering, 
s),  is  much  smaller  than  the  utricle.  Its  connexions  with  the  utricle  have  been  com- 
pared by  Fischer  to  those  of  the  crystalline  lens  with  the  vitreous  body :  it  occupies  the 
fovea  hemispherica  of  the  vestibule,  and  is  therefore  situated  below  the  utricle.  Accord- 
ing to  Soemmering,  it  does  not  adhere  to  the  utricle  ;  that  author  has  even  represented  a 
small  space  between  these  two  parts,  t  According  to  others,  there  is  a  communication 
between  them,  and  the  saccule  is  merely  a  supplementary  cavity  to  the  utricle.  I  have 
not  yet  been  able  to  satisfy  myself  concerning  this  point. 

The  membranous  labyrinth,  then,  is  quite  distinct  from  the  membrane  which  lines  the 
labyrinthic  cavities.  This  periosteal  membrane,  which  analogy  would  lead  us  to  regard 
as  a  fibro-serous  membrane,  is  the  only  membrane  which  is  prolonged  into  the  cochlea. 
We  might,  however,  regard  that  portion  of  the  lamina  spiralis  which  is  next  to  the  in- 
ner surface  of  the  lamina  gyrorum  as  a  portion  of  the  membranous  labyrinth. 

*  Alveus  utriculoaiis  of  Scarpa,  uiriculus  communis  of  ScEmmering,  Hnus  midian  of  M.  Breschet. 

t  Sacculus  teres  cum  utriculo  communi  nuUibi  cohseret,  et  ubi  cultri  apice  aperitur,  sphajricam  ormam  re- 
tinet.  (Explanation  of  fig.  2,  pi.  3.)  According  to  M.  Breschet,  the  sacculus  and  utriculus  adhere  intimately, 
and  he  is  inclined  to  believe  that  their  cavities  even  communicate  ;  but,  from  the  extreme  delicacy  of  tbeM 
•tructures,  he  has  been  unable  to  confirm  this  supposition 


THE    AUDITORY   NERVE,  ETC.  6S1 

The  Calcareous  Matter  of  the  Vestibule. — ^The  examination  of  the  ear  of  fishes,  which 
has  proved  of  such  assistance  in  investigating  the  structure  of  the  human  membranous 
labyrinth,  has  also  led  to  the  inquiry,  whether  there  existed  anything  in  the  human  ear 
analogous  to  the  solid  calcareous  concretions  found  in  the  labyrinth  of  the  ear  of  fishes. 
From  the  researches  of  M.  Breschet,  it  appears  that  the  labyrinthic  stones,  or  otolitkes, 
of  fishes,  are  represented  in  all  the  mammalia,  and,  consequently,  in  man,  by  a  cretace- 
ous powder,  which  he  has  named  otoconia  {ovc,  uroc,  the  ear,  and  Kovig,  dust) ;  and  that 
this  powder  exists  both  in  the  utricle  and  the  saccule,  collected  together  into  two  white 
shining  masses,  which  were  seen  and  described  by  both  Comparetti  and  Scarpa,  but 
were  mistaken  by  them  for  the  dried  acoustic  nerve.  Does  it  fulfil  the  same  uses  as  the 
otolithes  in  fishes  1  or  should  it  be  regarded  as  a  rudimentary  condition  of  an  important 
structure  in  other  animals  ] 

The  Auditory  Jferve  and  the  Vessels  of  the  Ear, 

The  auditory  nerve,  or  special  nerve  of  the  organ  of  hearing,  is  remarkable  for  its  soft- 
ness, and  hence  it  has  been  named  the  portio  mollis  of  the  seventh  cranial  nerve.  The 
auditory  nerve  arises,  at  least  in  part,  from  the  anterior  wall  of  the  fourth  ventricle ; 
having  reached  the  bottom  of  the  internal  auditory  meatus,  it  divides  into  two  branches  : 
an  ajiterior  and  larger,  distributed  to  the  cochlea,  and  a  posterior,  intended  for  the  vesti- 
bule and  semicircular  canals.  The  anterior  or  cochlear  branch  {t,fig.  264)  has  a  spiral 
arrangement,  like  that  portion  of  the  bottom  of  the  auditory  meatus  (d,fig.  260)  to  which 
it  proceeds,  and  it  enters  through  the  foramina  in  the  tractus  spiralis  of  the  lamina  cri- 
brosa.  One  set  of  nervous  filaments  enters  the  small  canals  in  the  centre  of  the  modi- 
olus {b,fig.  264) ;  the  others  are  applied  to  the  surface  of  the  modiolus  {t,Jlg.  263) ;  the 
latter  filaments  spread  out  upon  the  first  turn  of  the  lamina  spiralis  (<,  ^^.  265),  radiating 
in  the  most  regular  manner,  and  having  arrived  near  the  outer  border  of  the  spiral  lam- 
ina, they  each  divide  into  two  or  three  ramuscules,  which  anastomose  together,  so  as  to 
form  a  nervous  expansion.*  These  radiating  filaments  are  more  distinct  upon  the  lower 
than  upon  the  upper  surface  of  the  spiral  lamina. 

Those  filaments  of  the  nerve  which  are  not  spread  out  upon  the  first  turn  of  the  lami- 
na spiralis  pass  through  the  foramina  in  the  centre  of  the  modiolus,  and  spread  out  upon 
the  second  turn,  in  the  same  manner  as  those  already  described.  Lastly,  the  highest 
filaments  emerge  from  the  opening  at  the  apex  of  the  modiolus,  and  terminate  in  a  sim- 
ilar manner.  It  follows,  therefore,  that  the  nerves  of  the  cochlea  successively  diminish 
in  length,  as  the  spiral  lamina  does  in  width  ;  and  thus  the  radiating  nervous  filaments 
resemble  the  strings  of  a  harp,  in  becoming  successively  shorter  and  shorter.  It  is 
probable  that  this  arrangement  is  not  without  its  influence  upon  the  function  of  hearing. 
In  a  temporal  bone  softened  by  the  action  of  nitric  acid,  the  auditory  nerve,  the  modi- 
olus, the  spiral  lamina,  and  the  periosteal  membrane  which  lines  the  cochlea,  may  be 
dissected  with  the  greatest  facility. 

The  posterior  or  vestibular  division  of  the  auditory  nerve  is  subdivided  into  three 
branches,  the  largest  of  which  (v,  fig.  265)  is  distributed  to  the  utricle  {u)  and  to  the  am- 
pullae {o' p')  of  the  superior  vertical  and  horizontal  membranous  semicircular  canals  ;  the 
middle-sized  branch  is  distributed  to  the  sacculus  (s),  and  the  smallest  ends  in  the  am- 
pulla (g')  of  the  inferior  vertical  membranous  semicircular  canal,  t 

Bloodvessels  may  be  traced  into  the  membranous  labyrinth ;  most  of  them  enter  by 
the  internal  auditory  meatus  ;  those  which  belong  to  the  cochlea  pass  through  the  fora- 
mina in  the  modiolus,  and  are  distributed  in  a  radiating  manner  like  the  nerves 


THE  CEREBRO-SPINAL  AXIS. 
General  Observations. 


The  cerebrospinal  axis  constitutes  the  central  portion,  while  the  nerves  form  the  periph- 
eral portion  of  the  nervous  system. 

The  apparatus  of  innervation  formed  by  the  cerebro-spinal  axis  and  the  nerves  togeth- 
er, and  named  the  nervous  system,  is  the  most  important  part  in  the  animal  machine ;  it 
is  the  source  not  only  of  sensation  and  motion,  but  of  the  universal  sympathy  existing 
between  the  several  parts  of  the  animal  economy;  and  that  part  of  it  called  the  brain 
performs  the  highest  function  allotted  to  organized  beings,  by  becoming  the  immediate 
instrument  of  the  soul  in  the  exercise  of  the  intellectual  faculties. 

*  [According  to  observations  made  by  Treviranus,  Gottsche,  and  others,  the  filaments  of  the  cochlear  nerve 
in  animals  do  not  anastomose,  but  terminate  in  isolated  extremities,  which  are  in  some  cases  papillary  (TVe- 
viranus),  and  in  others  club-shaped  (Gottsche) ."^ 

t  [The  nervous  filaments  proceeding-  to  the  utricle  and  saccule  form  a,  fan-like  expansion  upon  those  sacs, 
per.etrate  into  their  interior,  and  spread  out  as  a  nervous  layer  on  their  internal  surface.  EacOi  of  the  nerves 
which  are  distributed  to  the  membranous  ampullar  apjiears  to  bifurcate,  so  as  partially  to  embrace  its  corre- 
sponding ampulla  in  a  transverse  direction  :  the  nervous  filaments  then  penetrate  into  the  ampulla,  and  spread 
out  iip<m  a  transverse  septum,  formed  in  its  interior  by  the  folding  inward  of  the  walls  of  the  cavity,  and  also 
upon  the  adjacent  parts  of  those  walls.     (See  Steifensand,  Mutter's  Arch.,  1835. )J 

4R 


682  NEUROLOGY. 

The  cerebro-spinal  axis  consists  of  that  soft,  pulpy,  elongated,  and  symmetrical  mass 
of  nervous  substance,  which,  becoming  enlarged  at  its  upper  part,  occupies  the  vertebral 
canal  and  the  cavity  of  the  cranium,  and  forms  the  centre  from  which  the  nerves  of  all 
parts  of  the  body  take  their  origin,  or  in  which  they  all  terminate. 

The  structure  of  no  other  organ  in  the  tody  excites  so  much  curiosity,  and,  unfortu- 
nately, there  is  none  whose  structure  is  involved  in  greater  obscurity.  Notwithstand- 
ing the  real  advances  that  have  recently  been  made  in  our  knowledge  of  the  anatomy  of 
the  brain,  we  must  still  acknowledge,  with  Steno,  that  the  human  mind,  which  has  car- 
ried its  investigations  even  into  the  heavens,  has  not  yet  been  able  to  comprehend  the 
nature  of  the  instrument  by  which  its  own  operations  are  performed,  and  that  its  pow- 
ers seem  to  abandon  it  as  soon  as  it  turns  its  attention  to  the  organ  in  which  it  resides. 
Until  the  end  of  the  last  century,  the  study  of  the  central  portion  of  the  nervous  system 
consisted  in  a  simple  enumeration  of  its  parts,  or,  rather,  in  a  more  or  less  imperfect 
description  of  its  external  surface,  and  of  the  different  objects  displayed  by  various  sec- 
tions. The  nomenclature  of  the  different  parts  of  the  encephalon*  is  alone  enough  to 
show  with  what  limited  views  the  researches  of  those  anatomists  must  have  been  made, 
who  did  not  suspect  that  this  pulpy-looking  mass — a  sufficient  definition  of  which  they 
believed  to  be,  that  it  held  an  intermediate  place  between  the  solids  and  the  fluids  of  the 
body — ^was  as  wonderful  in  the  delicacy  and  intricacy  of  its  structure,  as  in  the  impor- 
tance and  elevated  character  of  its  functions.  In  the  present  day,  anatomists  include 
in  the  study  of  the  encephalon  not  only  the  topographical  study  of  its  various  constituent 
parts,  but  also  the  determination  of  the  mode  in  which  those  parts  are  connected  togeth- 
er. To  ascertain  this  latter  point,  apart  from  all  questions  as  to  origin,  formation,  gen- 
eration, and  re-enforcement,  with  which  the  subject  has  lately  been  embarrassed,  should 
constitute  the  special  aim  of  every  inquiry  into  the  anatomy  of  this  part  pf  the  nervous 
system. 

The  central  portion  of  the  nervous  system  consists,  1.  Of  the  spinal  cord;  2.  Of  the  tu- 
ber annulare,  the  ■peduncles  of  the  cerebrum  and  cerebellum,  and  the  tubercula  quadrigemina  ; 
these  together  constitute  a  very  constricted  portion,  which  forms  the  bond  of  union  be- 
tween the  other  parts  of  the  encephalon,  and  which  I  shalll  accordingly  name  le  naeud  de 
I'encephale  ;t  3.  Of  the  cerebellum ;  4.  Of  the  cerebrum. 

The  cerebro-spinal  axis  is  surrounded  by  three  membranes  or  coverings,  called  the 
meninges  (from  /^^vty^,  a  membrane),  which  perform  some  important  functions  in  regard 
to  it,  and  which  must  in  the  very  first  place  occupy  our  attention. 


THE  MEMBRANES  OF  THE  CEREBRO-SPINAL  AXIS. 

General  Remarks. — The  Dura  Mater — the  Cranial  Portion,  its  Structure  and  Uses — the 
Spinal  Portion.  —  The  Arachnoid — its  Cranial  Portion  —  its  Spinal  Portion — the  Sub- 
arachnoid Fluids — their  Uses. — The  Pia  Mater — its  External  Cerebral  Portion. 

But  few  parts  of  the  body  are  so  effectually  protected  as  the  cerebro-spinal  axis  ;  this 
protection  is  afforded  in  part  by  the  vertebral  column,^  and  by  the  cranium,  the  mechan- 
ism of  which  we  have  already  described  as  being  so  eminently  calculated  to  defend  the 
parts  situated  within  them. 

Besides  the  osseous  case  formed  by  the  vertebro-cranial  column,  we  find,  surrounding 
the  cerebro-spinal  axis,  a  fibrous  sheath,  named  the  dura  mater ;  a  serous  membrane, 
called  the  arachnoid ;  and  a  proper  membrane,  named  the  pia  mater,  in  which  the  vessels 
of  the  nervous  centre  ramify. 

The  Duka  Matee.iJ 

Dissection  of  the  Dura  Mater  of  the  Scull. — Make  either  a  crucial  incision,  or  one  ex- 
tending from  before  backward,  or  from  ear  to  ear,  through  the  integuments  of  the  head ; 
turn  back  the  flaps,  taking  care  to  remove  the  periosteum  with  the  hairy  scalp. 

The  bones  of  the  cranium  being  thus  exposed,  the  scull-cap  may  be  removed,  either 
with  a  sort  of  hatchet  (marteau-hachette)  or  a  saw. 

This  hatchet  is  the  most  expeditious  and  the  best  instrument.  There  is  no  fear  of 
shaking  or  lacerating  the  brain,  if  the  instrument  be  properly  used  ;  but  it  is  almost  im- 
possible to  avoid  cutting  the  brain  with  the  saw,  the  only  advantage  of  which  over  the 
other  is,  that  it  makes  an  even  section. 

The  section  should  be  carried  quite  round  the  cranium,  about  a  finger's  breadth  above 

*  From  iv,  in,  and  Kt<pa\ii,  the  head  ;  a  convenient  term,  used  to  signify  that  part  of  the  cerebro-spinal  axis 
which  is  situated  within  the  cranium. 

t  [It  is  necessary  to  bear  in  mind  that  the  equivalent  term,  nodus  encephali,  has  been  assigned  by  Sccmmer- 
ing  to  the  pons  Varolii.] 

t  A  vertebrated  animal  may  also  be  defined  to  be  an  animal  provided  with  an  encephalon  ;  an  inter-vertebra- 
ted  animal  is  one  having  no  encephalon. 

^  The  application  of  the  term  mater  to  the  meninges  of  the  brain  is  derived  from  the  Arabians,  who  regard- 
ed these  membranes  as  the  origin,  or  mothers  of  all  the  other  parts  of  the  body  ;  or,  perhaps,  as  Ilaller  has  ob- 
lerved,  this  use  of  the  term  depends  upon  an  Arabic  idiom,  by  which  the  covering  of  any  body  whatsoever  is 
called  its  mother. 


EXTERNAL    SURFACE    OF   THE    DURA    MATER.  683 

the  orbital  arches,  the  scull-cap  being  raised  and  removed  by  means  of  the  narrow  end 
of  the  hatchet,  or  by  means  of  a  hook  attached  to  the  extremity  of  its  liandle. 

If  the  brain  is  not  to  be  preserved,  a  somewhat  different  method  of  proceeding  is  adopts 
ed.  Two  parallel  cuts  must  be  made  with  the  saw,  one  on  each  side  of  the  superior  lon- 
gitudinal sinus,  along  its  whole  extent.  Each  of  these  cuts  should  then  be  met  by  anoth- 
er, carried  horizontally  through  the  corresponding  side  of  the  scull.  When  the  two  por- 
tions of  bone  included  between  these  sections  are  removed,  there  remains  an  intermedi- 
ate portion  of  bone,  about  an  inch  wide,  extending  from  the  nasal  eminence  to  the  occip- 
ital protuberance.  The  dura  mater  should  then  be  divided  along  the  borders  of  this  in- 
termediate portion  of  bone,  and  the  brain  and  cerebellum  removed. 

If,  however,  it  be  intended  to  preserve  the  brain  and  cerebellum,  after  the  entire  scull- 
cap  has  been  removed  in  the  ordinary  manner,  the  dura  mater  must  be  divided  circularly, 
along  the  cut  edge  of  the  cranium,  the  anterior  extremity  of  the  falx  cerebri  must  be  di- 
vided with  the  scissors,  and  the  whole  fibrous  cap  turned  backward. 

Another  mode,  and  one  which  I  prefer,  is,  to  make  an  incision  through  the  dura  mater, 
along  each  side  of  the  superior  longitudinal  sinus,  and  then  to  divide  the  anterior  ex- 
tremity of  the  falx,  and  reflect  that  part  backward. 

Dissection  of  the  Dura  Mater  in  the  Vertebral  Canal. — This  part  of  the  dura  mater  may 
be  exposed,  either  by  removing  the  arches  of  the  vertebrae,  or  by  taking  away  the  bodies 
of  these  bones.     The  latter  method  is  but  seldom  adopted. 

The  arches  of  the  vertebrae  may  be  removed  by  means  of  a  chisel  and  mallet,  or,  still 
better,  by  the  rachitame. 

An  instrument  has  lately  been  invented,  consisting  of  two  parallel  saws,  slightly  con- 
vex on  their  toothed  edges,  firmly  connected  together,  but  capable  of  being  separated  or 
approximated  as  may  be  desired.  Preference  is  justly  given  to  the  rachitome  over  this 
complicated  instrument.  The  important  object  in  opening  the  spine  is,  to  make  the  sec- 
tion opposite  the  junction  of  the  laminae  with  the  transverse  and  articular  processes. 

In  order  to  display  the  continuity  of  the  cranial  and  spinal  portions  of  the  dura  mater, 
it  is  necessary  to  connect  the  sections  already  made  in  the  head  and  spine,  by  removing 
with  the  saw  the  intervening  portion  of  the  occipital  bone. 

A  beautiful  preparation  of  the  dura  mater  may  be  made  by  removing  the  roof  and  sides 
of  the  scull,  and  the  arches  of  all  the  vertebrae  ;  by  then  taking  out  the  encephalon  and 
spinal  cord  through  incisions  in  the  dura  mater,  which  may  be  readily  concealed ;  and 
by  filling  the  cavity  thus  left  with  tallow,  which  is  afterward  to  be  dissolved  out  by  spir- 
its of  turpentine,  or,  what  is  easier  to  do,  the  cavity  of  the  dura  mater  may  be  filled  with 
fine  sand. 

The  dura  mater  (meninx  crassa,  Galen;  le  meninge,  Chauss.)  is  a  fibrous  membrane 
which  covers  and  protects  the  cerebro-spinal  axis,  and  the  roots  of  all  the  nerves  which 
arise  from  or  terminate  in  that  portion  of  the  nervous  system. 

It  is  the  most  external  of  the  membranes  of  the  brain  and  spinal  cord  (meninx  exteri- 
or, Smmmering) ;  it  consist  of  a  cranial  and  a  spinal  portion. 

The  Cranial  Portion  of  the  Dura  Mater. 

The  cranial  portion  of  the  dura  mater  forms  a  fibrous  sac,  which  lines  the  internal  sur- 
face of  the  bones  of  the  cranium,  forming  their  internal  periosteum,  and  at  the  same  time 
serves  £is  a  covering  for  the  encephalon,  and  separates  its  different  parts  by  means  of 
.prolongations  or  incomplete  septa. 

The  dura  mater  in  the  scuU  presents  for  our  consideration  an  external  and  an  internal 
surface. 

External  Surface  of  the  Dura  Mater. 

Its  external  surface  is  accurately  moulded  upon  the  internal  surface  of  the  bones  of  the 
cranium,  to  which  it  adheres  by  a  multitude  of  small  fibrous  and  vascular  prolongations, 
which  can  be  readily  displayed  by  putting  the  membrane  under  water.  These  prolonga- 
tions give  the  external  surface  of  the  dura  mater  a  rough  appearance,  which  contrasts 
strongly  with  the  smooth  aspect  of  its  internal  surface.  The  ramifications  of  the  mid- 
dle meningeal  arteries  and  veins  are  seen  on  the  external  surface  of  the  membrane,  and 
project  from  it,  as  if  they  were  only  laid  upon  it. 

The  dura  mater  adheres  to  the  parieties  of  the  cranium  with  different  degrees  of 
firmness  in  different  situations. 

Thus,  it  is  generally  less  firmly  adherent  to  the  roof  of  the  scull  than  to  its  base,  where 
it  is  impossible  to  separate  it  from  the  bone.  The  upper  border  of  the  petrous  portion 
of  the  temporal  bone,  the  posterior  border  of  the  lesser  wings  of  the  sphenoid,  and  the 
margin  of  the  foramen  magnum,  are  points  to  which  it  is  very  firmly  attached  ;  but  the 
dura  mater  adheres  more  strongly  opposite  the  sutures  than  in  any  other  situation.  Upon 
the  orbital  plates,  on  the  occipital  fossae,  and  upon  the  squamous  portion  of  each  temporal 
bone,  it  adheres  so  slightly,  that  it  has  been  conceived  to  be  altogether  unattached  in 
those  regions.* 

*  An  erroneous  opinion  for  a  long  time  prevailed  that  the  adhesions  between  the  dura  mater  and  the  hones 


6S4  NEUROLOGY. 

The  firmness  of  the  adhesion  between  the  dura  mater  and  the  bones  varies  at  differ- 
ent periods  of  life,  and  also  the  manner  in  which  it  is  effected.  Thus,  in  old  subjects, 
the  parts  are  so  closely  united,  that  it  is  almost  impossible  to  take  off  the  roof  of  the 
Bcull  without,  at  the  same  time,  removing  portions  of  the  dura  mater.  When  this  hap- 
pens, there  is  ossification  of  the  outermost  layers  of  this  membrane.  In  the  new-born 
infant,  the  adhesion  is  firmer  than  in  the  adult,  especially  opposite  the  sutures. 

As  to  the  mode  in  which  this  adhesion  is  effected,  it  may  be  stated,  that  in  the  infant 
it  appears  to  be  exclusively  by  means  of  vessels ;  in  old  age,  almost  entirely  by  fibrous 
tissue  ;  and  in  the  adult,  by  partly  vascular  and  partly  fibrous  prolongations. 

The  dura  mater  is,  moreover,  attached  to  the  bones  of  the  cranium  by  means  of  the 
fibrous  canals  formed  by  this  membrane  for  the  nerves  and  vessels  which  pass  through 
the  foramina  in  the  base  of  the-  scull. 

The  most  remarkable  prolongations  of  the  cranial  portion  of  the  dura  mater,  except- 
ing that  for  the  spinal  cord,  are  those  given  off  opposite  the  right  and  left  sphenoidal 
fissures.  Each  of  these  prolongations  separates  into  two  layers,  one  of  which  forms  the 
sheath  of  the  corresponding  optic  nerve,  while  the  other  blends  with  the  periosteum 
lining  the  cavity  of  the  orbits. 

The  Internal  Surface  of  the  Dura  Mater. 

The  internal  surface  of  the  cranial  portion  of  the  dura  mater  appears  smoothly  polished, 
and  is  constantly  lubricated  with  serosity ;  its  polished  appearance  is  owing  to  a  layer 
of  arachnoid  with  which  it  is  covered  ;  this  layer  is  so  thin  that  one  might  be  disposed 
to  deny  its  existence,  and  it  is  so  firmly  united  to  the  dura  mater  that  its  demonstration 
is  extremely  difficult.  Excepting  at  the  points  where  the  cerebral  veins  enter  the  dif- 
ferent sinuses,  the  internal  surface  of  the  dura  mater  lined  by  the  arachnoid  is  free,  and 
is  in  contact  with  the  cerebral  arachnoid,  and  indirectly  with  the  outer  surface  of  the 
encephalon. 

From  this  surface  certain  prolongations  or  imperfect  septa  are  given  off,  by  which  the 
cavity  of  the  cranium  is  divided  into  several  compartments.  These  septa  are  three  in 
number,  viz.,  the  falx  cerebri,  the  tentorium  ccrebelH,  and  the  falx  cerehelli. 

The  Falx  Cerebri. — This  is  a  fibrous  lamina  {d,  fig.  220),  which  is  placed  vertically 
along  the  median  line,  is  shaped  like  a  sickle,  and  extends  from  the  foramen  caecum  to 
the  tentorium  cerebelli.  Its  point,  which  is  in  front,  dips  into  the  foramen  caecum,  and 
envelops  the  crista  galli ;  its  base  is  behind,  and  rests  perpendicularly  upon  the  middle 
of  the  tentorium  cerebelli.  The  venous  canal,  called  the  straight  sinus,  is  situated  along 
the  line  in  which  the  falx  and  the  tentorium  meet.  The  upper  border  of  the  falx  is  con- 
vex, and  extends  from  the  foramen  caecum  to  the  internal  occipital  protuberance.  In 
this  border  is  placed  the  superior  longitudinal  sinus. 

The  lower  border  is  concave,  thin,  sharp,  and  free,  and  corresponds  to  the  corpus  cal- 
losum,  touching  that  body,  however,  only  at  the  back  part,  and,  according  to  some  anat- 
omists, making  a  rather  deep  furrow  upon  it.  This  free  border,  which  is  thicker  behind 
than  in  front,  contains  within  it  a  small  vein,  which  has  been  named  the  inferior  longi- 
tudinal si7ius.  The  two  surfaces  of  the  falx  correspond  to  the  internal  surfaces  of  the 
two  hemispheres  of  the  brain.  Not  unfrequently  the  falx  cerebri  is  found  as  if  torn 
through  in  some  points,  and  I  once  observed  the  two  hemispheres  continuous  with  each 
other  through  an  opening  in  this  septum. 

The  use  of  the  falx  is  evidently  to  obviate  the  effects  of  lateral  concussion  of  the 
brain,  and  to  prevent  one  hemisphere  from  pressing  upon  the  other,  while  the  person  is 
lying  upon  his  side. 

The  Tentorium  Cerebelli. — This  is  an  imperfect  horizontal  septum  (le  septum  trans- 
verse, Chauss.),  which  is,  as  it  were,  notched  in  front,  and  which  separates  the  cerebrum 
from  the  cerebellum.  It  is  constantly  in  a  state  of  tension  ;  a  condition  which  depends 
upon  the  permanently  tense  state  of  the  falx  cerebri.  These  two  parts,  indeed,  mutually 
preserve  each  other's  tension,  and  when  either  of  them  is  cut,  the  other  necessarily  be- 
comes relaxed.  It  is,  therefore,  only  when  the  tentorium  is  examined  in  situ,  and  the 
falx  is  left  uninjured,  that  the  anatomy  of  the  former  can  be  properly  understood.  It  is 
then  seen  that  it  represents  two  planes,  inclined  upward,  and  united  in  the  middle  line 
at  an  obtuse  angle,  so  as  to  form  a  sort  of  arch,  upon  the  top  of  which  the  base  of  the 
falx  cerebri  rests.  The  concavity  of  this  arch  corresponds  to  and  is  accurately  fit  ted 
upon  the  convex  upper  surface  of  the  cerebellum  below  ;  the  convexity  corresponds  to 
the  slightly  concave  under  surface  of  the  posterior  lobes  of  the  cerebrum. 

Its  outer  or  convex  border  is  directed  horizontally ;  it  corresponds  behind  to  the  posterior 
portion  of  the  lateral  grooves,  and  in  front  to  the  upper  border  of  the  pars  petrosa.  The 
lateral  sinus  occupies  the  whole  occipital  portion  of  this  border. 

Its  inner  or  concave  border  is  parabolic  ;  between  it  and  the  basilar  groove,  in  front,  a 
small  space  is  intercepted,  which  is  occupied  by  the  nodus  encephali,  being  accurately 

were  the  results  of  disease  ;  and  it  has  even  been  believed  that  a  space  existed  between  the  dura  mater  and 
the  bones  of  the  cranium.  These  errors  resulted  from  a  physiological  hj-pothesis,  vi-hich  attributed  the  move- 
ments of  the  brain  to  contraction  of  the  dura  mater. 


STRUCTURE   OP   THE    DURA   MATER.  66S 

adapted  to  that  part  of  the  brain.  The  extremities  of  the  external  and  internal  borders 
cross  each  other  on  each  side  like  the  letter  X  ;  the  extremities  of  the  outer  border  are 
attached  to  the  posterior  clinoid  processes,  and  form  on  each  side  a  sort  of  bridge,  near 
the  apex  of  the  pars  petrosa,  beneath  which  the  fifth  cranial  nerve  passes  ;  the  extremi- 
ties of  the  inner  border  are  prolonged  above  those  of  the  outer  border,  and  are  attached 
to  the  anterior  clinoid  processes.  They  form  the  sides  of  the  pituitary  fossa,  and  con- 
tain in  their  substance  the  cavernous  sinuses. 

The  Falx  Cerebelli. — This  is  a  small  falciform  fold,  situated  vertically  in  the  median 
line  (le  septum  median  du  ceverlet,  Chauss.) ;  Winslow  remarks  that  it  is  sometimes 
double.  It  extends  from  the  internal  occipital  protuberance  to  the  foramen  magnum, 
and  separates  the  two  hemispheres  of  the  cerebellum.  Its  base,  directed  upward,  cor- 
responds with  and  is  attached  to  the  tentorium  cerebelli ;  its  apex  bifurcates  upon  the 
sides  of  the  foramen  magnum.  Its  posterior  border  corresponds  with  the  internal  crest 
of  the  occipital  bone,  and  its  anterior  border  with  the  bottom  of  the  median  fissure  of  the 
cerebellum. 

Structure. 

The  dura  mater  is  perhaps  the  thickest  and  strongest  of  all  the  membranous  invest- 
ments of  the  viscera.  It  may  be  regarded  as  consisting  of  two  veiy  distinct  fibrous  lay- 
ers :  of  an  external  or  periosteal  layer,  which  forms  the  internal  periosteum  of  the  bones 
of  the  cranium  ;  and  of  an  internal  or  proper  cerebral  layer,  which,  though  blended  with  the 
preceding  throughout  the  greatest  part  of  its  extent,  is  separated  from  it  at  certain  points, 
in  order  to  form  both  the  fibrous  canals,  which  are  called  the  sinuses,  and  also  the  sev- 
eral folds  just  described  as  projecting  from  the  internal  surface  of  the  dura  mater.  Thus, 
the  periosteal  layer  of  the  dura  mater  enters  into  and  lines  the  longitudinal  groove,  but 
the  central  layer  passes  off  from  it  on  either  side ;  and  the  two  laminae  thus  formed  by 
the  right  and  left  portions  of  the  cerebral  layer  approach  each  other,  so  as  to  include 
between  themselves  and  the  periosteal  layer  lining  the  groove  a  long  three-sided  inter- 
val, which  forms  the  superior  longitudinal  sinus. 

The  internal  layer  of  the  dura  mater,  which  is  essentially  fibrous,  must  not  be  con- 
founded with  the  arachnoid  membrane  by  which  its  internal  surface  is  lined,  and  which 
will  be  presently  described. 

The  dura  mater  is  evidently  composed  of  fibrous,  not  of  muscular  tissue,  as  was  for  a 
long  time  believed.* 

It  consists  of  fibres  which  interlace  in  various  directions 

Anatomists  generally  describe,  in  connexion  with  the  dura  mater,  those  white  granu- 
lar bodies  which  are  chiefly  collected  into  clusters  along  the  superior  longitudinal  sinus, 
and  which  are  improperly  called  glands  (the  glands  of  Pacchioni,  from  the  name  of  the 
author  who  first  gave  a  good  description  of  them). 

These  bodies  are  not  found  in  infants,  but  exist  almost  constantly  in  the  adult,  and 
are  very  numerous  in  old  subjects.  They  are  sometimes  single  and  sometimes  collect- 
ed into  groups ;  they  are,  at  first,  formed  upon  the  internal  surface  of  the  dura  mater, 
but  after  a  time  they  displace  the  fibres  of  the  internal  layer,  and  separate  them  into 
small,  parallel,  or  reticulated  fasciculi,  and,  in  this  way,  insinuate  themselves  between 
the  two  layers  of  the  membrane.  In  this  situation  they  form  tumours,  which  project 
upon  the  external  surface  of  the  dura  mater,  and  occupy  corresponding  depressions  form- 
ed in  the  bones  of  the  cranium.  The  rough  and  irregular  depressions  so  frequently 
found  in  the  parietal  bones  of  old  subjects,  and  ascribed  by  the  older  anatomists  to  caries 
of  the  bone,  are  occasioned  by  the  clusters  of  these  granular  bodies. 

These  bodies  often  insinuate  themselves  along  the  obliquely  running  veins  into  the 
substance  of  the  walls  of  the  sinuses,  and  project  into  the  interior  of  the  veins  and  si- 
nuses, so  as  apparently  to  be  in  direct  contact  with  the  blood ;  but  they  are,  in  reality, 
separated  from  that  fluid  by  the  lining  membrane  of  the  vessels  and  sinuses. 

Although  these  bodies  are  principally  collected  along  the  superior  longitudinal  sinus, 
they  are  also  found,  as  Haller  remarks,  opposite  the  anterior  extremity  of  the  straight 
sinus.  I  have  seen  a  small  pedunculated  mass  of  them,  which  projected  into  the  inte- 
rior of  the  horizontal  portion  of  one  of  the  lateral  sinuses,  and  might  have  impeded  the 
circulation. 

I  consider  that  the  bodies  in  question  are  seated  in  the  sub-arachnoid  cellular  tissue  ; 
in  fact,  they  are  often  found  beneath  the  arachnoid,  at  some  distance  from  the  longitu- 
dinal sinus,  along  the  superior  cerebral  veins.  They  always  project  at  first  upon  the  in- 
ternal surface  of  the  dura  mater,  and  then  insinuate  themselves  into  the  substance  of 
that  membrane. 

What  is  the  nature  of  these  bodies  1  Ruysch  noticed  them,  and  considered  them  to 
be  of  a  fatty  nature.     Some  authors  have  likened  them  to  the  granulations  so  frequently 

*  Pacchioni,  who  wrote  a  treatise  of  some  length  upon  this  membrane,  even  went  so  far  as  to  admit  the  exist- 
ence of  three  fleshy  bellies,  viz.,  one  for  each  hemisphere,  and  a  third  for  the  cerebellum.  The  same  author 
gives  a  very  minute  description  of  the  direction  of  the  different  layers  of  fibres  in  the  dura  mater.  I  do  not 
believe  that  there  exists  in  the  history  of  our  science  a  more  striking  example  of  the  misapplication  of  tcitu- 

r;il  anaton.y. 


686  NEUROLOGY. 

found  in  the  choroid  plexuses ;  but  there  is  not  the  slightest  resemblance  between  the 
two.  Pacchioni  regarded  them  as  glands  which  secreted  a  peculiar  lymph.  He  has 
even  described  certain,  so  called,  excretory  ducts,  which  have  been  said  by  others  to 
enter  the  superior  longitudinal  sinus.  Those  clusters  which  project  into  the  sinuses 
have  been  supposed  to  act  as  valves.  It  has  been  said  that  these  bodies  are  lymphatic 
glands  ;  this,  also,  is  erroneous  ;  and,  indeed,  it  is  better  to  confess  our  ignorance  of  their 
nature.  They  occur  so  frequently  that  they  cannot  be  regarded  as  morbid  productions. 
Their  absence  in  the  infant,  and  their  much  greater  abundance  in  the  old  subject  than  in 
the  adult,  are  the  principal  features  in  their  history. 

Vessels. — In  respect  of  the  number  and  size  of  its  vessels,  the  cranial  dura  mater 
seems  to  form  an  exception  to  fibrous  membranes  in  general,  which  are  remarkable  for 
their  slight  vascularity.  It  receives,  in  fact,  the  following  arteries  :  the  middle  menin- 
geal, which  is  a  branch  of  the  internal  maxillary  artery ;  the  anterior  meningeal,  from 
the  ethmoidal  artery ;  and  the  posterior  meningeal,  from  the  ascending  pharyngeal,  or 
pharyngo-meningeal.  Nevertheless,  if  we  consider  that  these  vessels  are  situated  be- 
tween the  dura  mater  and  the  bones,  and  that  they  are  ahnost  entirely  distributed  to  the 
bones,  we  shall  be  able  to  account  for  the  apparent  anomaly  in  the  number  and  size  of 
these  vessels. 

The  veins  of  the  dura  mater  are  two  venae  comites  for  each  meningeal  artery,  and  the 
small  veins  which  enter  the  sinuses  ;  the  venous  sinuses  themselves  are  situated  be- 
tween the  two  layers  of  this  membrane. 

The  lymphatics  form  a  network  upon  the  internal  surface  of  the  dura  mater,  but  do  not 
appear  to  belong  to  the  proper  fibrous  tissue. 

Nerves  of  the  Dura  Mater. — On  consulting  the  various  writers  upon  this  subject,  it  is 
found  to  be  involved  in  the  strangest  perplexity :  some  authors  admit,  while  others  deny 
in  the  most  positive  manner,  the  existence  of  nerves  in  this  membrane  ;  and  those  who 
do  admit  their  existence,  differ  altogether  in  regard  to  their  origin. 

Modem  anatomists,  with  Haller,  Wrisberg,  and  Lobstein,  state  that  there  are  no 
nerves  in  the  dura  mater ;  on  the  other  hand,  Vieussens,  Winslow,  Lieutaud,  Lecat,  Val- 
salva, and  others,  declare  that  they  have  observed  them.  Valsalva  says  that  they  are 
derived  from  the  seventh  pair ;  all  the  other  authors  state  that  they  arise  from  the  fifth ; 
but  they  do  not  agree  as  to  the  exact  point  of  origin,  which,  according  to  some,  is  the 
Gasserian  ganglion ;  and  according  to  others,  either  the  ophthalmic,  or  the  superior  or 
inferior  maxillary  divisions  of  that  nerve.  Chaussier  admits  their  existence,  and  says 
that  they  are  derived  from  the  ganglionic  system ;  but  it  is  evident  that  he  has  been  led 
to  this  conclusion  from  theory,  and  not  from  actual  observation. 

Accident  has  enabled  me  most  distinctly  to  demonstrate  nerves  in  the  dura  mater. 
In  a  head  which  had  been  macerated  in  diluted  nitric  acid,  and  afterward  in  water,  the 
dura  mater  having  become  transparent  and  jelly-like,  I  was  surprised  to  see  within  its 
substance  certain  white  lines  exactly  resembhng  nervous  filaments.  I  cut  down  to  these 
white  lines,  ascertained  that  they  were  nerves,  and  dissected  them  throughout  their 
whole  course.  I  recognised  on  each  side  of  the  middle  line  two  nervous  filaments  which 
came  from  the  fifth  nerves,  and  reached  nearly  to  the  superior  longitudinal  sinus.  There 
was  a  third  nervous  filament  in  the  substance  of  the  tentorium  cerebelli,  but  I  could  not 
ascertain  its  origin.* 

Uses  of  the  Cranial  Dura  Mater. — The  dura  mater  serves  as  an  internal  periosteum  for 
the  bones  of  the  cranium,  with  which  it  has  numerous  vascular  connexions  ;  and  it  also 
covers  and  defends  the  encephalon.  Its  prolongations  separate  from  each  other  the  dif- 
ferent parts  of  the  encephalon,  and  in  some  measure  prevent  the  effects  of  concussion. 
It  also  contains  within  its  substance  certain  venous  canals,  in  which  aU  the  blood  is  re- 
turned from  the  encephalon. 

The  Spinal  Portion  of  the  Dura  Mater. 

The  spinal  portion  of  the  dura  mater  forms  a  long  fibrous  tube,  which  is  prolonged  from 
the  cranial  dura  mater,  and  extends  from  the  occipital  foramen  to  the  termination  of  the 
sacral  canal. 

In  order  to  ascertain  the  capacity  of  this  fibrous  sheath,  it  must  be  first  distended  with 
an  injection :  it  is  then  seen  to  form  a  funnel-shaped  tube,  which  is  of  considerable  size 
in  the  cervical  region,  becomes  contracted  in  the  dorsal  region,  is  again  expanded  in  the 
lumbar  region,  and  terminates  in  the  sacral  region  by  subdividing  into  a  number  of  sheaths 
for  the  sacral  nerves.  When  distended,  the  spinal  portion  of  the  dura  mater  almost  en- 
tirely fills  the  bony  canal  formed  by  the  vertebral  column.  Why  the  cavity  of  the  dura 
mater  (d,  fig.  266,  A  B)  should  be  larger  than  the  spinal  cord  (s),  a  question  the  solution 
of  which  had  exercised  the  ingenuity  of  almost  all  anatomists,  has  been  well  answered 
by  Cotugno — it  is  for  the  purpose  of  containing  a  serous  fluid,  t 

*  [The  tentorium  receives  a  branch  from  the  fourth  cranial  nerve  (see  description  of  that  nerve).] 

t  "  Quidciuid  autera  spatii  est  inter  vaginam  durae  matris  et  meduUam  spinalem,  id  omne  plenum  etiam  sem 

per  est ;  non  medullft.  quidem  ips&  in  viventibus  turgidiori,  non  nube  vaporos^,  quod  in  re  adhuc  obscurft  sus 

picantur  summi  ^nri  ;  sed  aqu&  ei  quidem  simili,  quam  circa  cor  coutinet  pericardium,  quae  caveas  cerebri  ven 

triculorum  adimplet,  quae  auris  labyrinth um,  quae  reliquas  tandem  complet  corooris  caveas,  libero  aeri,  nequa 

" — '  rjf  Ischiade  Nervosa,  p.  U.) 


THE   CRANIAL   PORTION   OF    THE   ARACHNOID. 

The  external  surface  of  the  spinal  portion  of  the  dura  mater,  unlike,  in  this  respect,  to 
the  cranial  portion,  scarcely  adheres  to  the  bony  parietes  of  the  spinal  canal.  Covered 
by  a  plexus  of  veins  behind,  it  has  no  attachment  at  all  to  the  arches  of  the  vertebrae,  nor 
to  the  yellow  ligaments  ;  the  intervals  between  those  parts  and  the  membrane  is  occu- 
pied by  a  soft,  reddish,  adipose  tissue  intermixed  with  veins,  which,  in  the  foetus,  and 
during  infancy,  is  infiltrated  with  serosity.  This  fat,  which  is  most  abundant  in  the  sa- 
cral region,  may  be  most  aptly  compared  to  the  marrow  of  the  long  bones,  with  which 
it  has  so  much  analogy  in  respect  of  its  use.  In  one  class  of  vertebrated  animals,  viz., 
fishes,  a  precisely  similar  kind  of  fat  is  accumulated  in  large  quantities  in  the  cranium, 
always  filling  up  the  spaces  left  by  the  contained  organs. 

In  front,  the  external  surface  of  the  dura  mater  adheres  to  the  posterior  common  ver- 
tebral ligament  by  fibrous  bands  prolonged  from  it  at  intervals. 

On  each  side,  the  spinal  portion  of  the  dura  mater  gives  off  fibrous  sheaths  {I,  fig.  266  ; 
h',  fig.  267)  for  the  roots  of  the  spinal  nerves  (w),  which  sheaths  accompany  the  nerves 
beyond  the  inter-vertebral  foramina,  and  are  lost  in  the  cellular  tissue. 

The  internal  surface  of  this  part  of  the  dura  mater  is  smooth  and  moist,  in  consequence 
of  being  covered  by  a  serous  layer,  viz.,  the  arachnoid  (a).  Down  each  side  of  this  sur- 
face are  seen  the  double  orifices  of  the  several  fibrous  canals,  which  transmit  the  ante- 
rior and  posterior  roots  of  the  spinal  nerves.  It  is  very  rarely  found  entirely  free  from 
adhesions  to  the  arachnoid  ;  and  it  is  necessary  to  be  careful  not  to  confound  these  ad- 
hesions, which  are  always  met  with  at  isolated  points,  with  such  as  are  the  result  of 
morbid  action. 

The  inferior  extremity  of  the  spinal  portion  of  the  dura  mater  is  situated  opposite  the 
bottom  of  the  lumbar  region,  and  it  therefore  extends  much  lower  than  the  spinal  cord ; 
this  extremity  is  formed  into  a  large  ampulla  around  the  cauda  equina,  which  enlarge- 
ment seems  to  be  of  use  only  as  a  reservoir  for  the  cephalo-rachidian  fluid. 

Its  superior  extremity  is  firmly  attached  to  the  margin  of  the  foramen  magnum,  and  is 
continuous  with  the  cranial  portion  of  this  membrane.  In  consequence  of  the  firm  ad- 
hesion of  this  membrane  to  the  margin  of  the  foramen  magnum,  and  of  its  attachment 
to  the  sacrum  by  means  of  the  sheaths  for  the  sacral  nerves,  and  to  the  sides  of  the  ver- 
tebred  column  by  those  for  the  cervical,  dorsal,  and  lumbar  nerves,  it  is  constantly  main- 
tained in  a  state  of  tension  highly  favourable  to  its  use  as  a  protecting  covering  of  the 
spinal  cord. 

Vessels. — The  vessels  of  the  spinal  dura  mater  are  much  less  numerous  than  those  of 
the  cranial  portion ;  for  these  belong  exclusively  to  it,  and  not  to  the  surrounding  bones. 

Its  arteries  arise  from  the  spinal  branches  of  the  arteries  of  the  cervical,  dorsal  lum- 
bar, and  sacral  regions.     Its  veins  terminate  in  the  intra-spinal  veins. 

The  lymphatic  vessels  observed  appear  rather  to  belong  to  the  arachnoid. 

The  nerves  of  this  membrane  have  not  yet  been  demonstrated  ;  but  experiments  upon 
living  animals,  especially  upon  dogs,  have  convinced  me  that  the  cranial,  and  probably, 
also,  the  spinal  portion  of  the  dura  mater,  although  insensible  to  the  knife,  are  extreme- 
ly sensible  to  laceration. 

The  Arachnoid. 
The  cerebro-spinal  axis  is  surrounded  by  a  serous  membrane  named  the  arachnoid, 
which,  like  all  membranes  of  this  kind,  forms  a  shut  sac,  adherent  by  its  external  sur- 
face, but  free  and  smooth  on  its  internal  surface.    We  shall  first  describe  the  cranial,  and 
then  the  spinal  portion  of  the  arachnoid. 

The  Cranial  Portion  of  the  Arachnoid. 

Dissection. — The  arachnoid  may  be  shown  upon  the  convex  surface  of  the  brain  with- 
out any  preparation,  if  the  sub-arachnoid  cellular  tissue  be  infiltrated.  It  can  also  be 
very  easily  demonstrated  by  blowing  air  under  it. 

The  arachnoid  membrane,  which,  from  its  extreme  tenuity,  was  for  a  long  time  con- 
founded with  the  pia  mater,  was  demonstrated  by  Ruysch  upon  the  convex  surface  of 
the  brain  by  injecting  air  beneath  it ;  it  was  shown  by  Varolius  upon  the  base  of  that 
organ,  and  its  arrangement  in  that  situation  was  figured  by  Casserius.  It  was  descri- 
bed first  by  the  Anatomical  Society  of  Amsterdam  as  a  special  membrane  covering  the 
brain,  under  the  name  of  the  arachnoid;  and  Bichat,  reasoning  from  analogy,  demonstra- 
ted that  it  not  only  forms  a  covering  for  the  brain,  but  is  also  reflected  upon  the  dura 
mater,  and  lines  it  through  its  whole  extent.  He  also  believed  that  it  was  continuous 
with  the  lining  membrane  of  the  ventricles,  an  error  which  has  been  successfully  refu- 
ted by  M.  Magendie. 

Like  all  serous  membranes,  the  arachnoid  presents  a  visceral  and  a  parietal  layer 

The  Visceral  Layer  of  the  Arachnoid. 

The  visceral  layer  of  the  cranial  portion  of  the  arachnoid  requires  to  be  exammed  upon 
the  convex  surface  and  the  base  of  the  brain. 

Upon  the  base  of  the  brain,  the  arachnoid  is  separated  from  this  organ  in  a  great  num- 


NEUEOLOGY. 

ber  of  points,  and  more  particularly  as  it  is  passing  from  one  lobe  to  another.  We  shdll 
-examine  in  detail  the  arrangement  of  this  part  of  the  membrane. 

In  the  median  line,  in  frmit,  it  dips  between  the  anterior  lobes  of  the  brain,  but  only  at 
the  fore  part ;  behind,  it  connects  these  lobes  by  passing  directly  from  one  to  the  other ; 
it  covers  the  lower  surface  of  the  optic  nerves  and  optic  commissure,  then  the  tuber 
cinereum  and  the  infundibulum,  for  the  latter  of  which  it  forms  a  sheath,  and  is  then  re- 
flected above  the  pituitary  body ;  from  the  tuber  cinereum  it  passes  across  to  the  pons 
Varolii,  leaving  a  hollow  space  between  it  and  the  brain,  which  is  traversed  by  a  few 
dense  fibrous  filaments. 

I  shall  call  this  space  the  anterior  sub-arachnoid  space ;  it  may  be  regarded  as  the  prin- 
cipal reservoir  of  the  serous  fluid  of  the  cranium. 

In  the  median  line,  lehind,  the  arachnoid  lines  the  furrow  between  the  posterior  lobes 
of  the  brain,  and  is  reflected  from  the  corpus  callosum  upon  the  superior  vermiform  pro- 
cess of  the  cerebellum :  at  this  point  it  meets  with  the  venae  Galeni,  and  generally  forms 
a  circular  fold  around  them,  which  was  compared  by  Bichat  to  the  foramen  of  Wins- 
low  in  the  peritoneum,  and  which  he  supposed  to  be  the  orifice  of  an  arachnoid  canal, 
which  opened  into  the  third  ventricle  beneath  the  velum  interpositum. 

The  arachnoid  covers  the  whole  upper  surface  of  the  cerebellum  ;  and,  having  reached 
the  great  circumference  of  that  organ,  it  passes  like  a  bridge  from  one  hemisphere  to  the 
other,  and  from  the  cerebellum  itself  to  the  posterior  surface  of  the  spinal  cord.  In  thus 
passing  from  one  hemisphere  of  the  cerebellum  to  the  other,  and  from  the  cerebellum 
to  the  spinal  cord,  the  arachnoid  leaves  a  considerable  space  or  reservoir  for  serosity, 
which  may  be  called  the  posterior  sub-arachnoid  space. 

Laterally,  the  arachnoid  covers  the  inferior  surface  of  the  anterior  lobes  of  the  cere- 
brum and  the  olfactory  nerves,  which  are  thus  held  in  contact  with  the  anterior  lobes  ; 
it  then  passes  from  the  anterior  to  the  posterior  lobe,  without  entering  the  fissure  of 
Sylvius,  and  from  the  posterior  lobe  to  the  tuber  annulare  and  the  cerebellum.  It  fol- 
lows, therefore,  that  there  are  certain  small  sub-arachnoid  spaces  which  communicate 
with  the  great  anterior  sub-arachnoid  space  of  the  brain  ;  so  that  in  the  dead  body  there 
exists,  between  the  arachnoid  and  the  pia  mater,  at  the  base  of  the  brain,  a  large  space, 
the  centre  of  which  corresponds  to  the  median  excavation  of  the  base  of  the  cerebrum, 
and  which  is  prolonged  forward  between  the  anterior  lobes  of  the  brain,  laterally  along 
each  of  the  fissures  of  Sylvius,  and  backward,  around  the  peduncles  of  the  cerebellum. 
By  this  last-named  prolongation  a  communication  is  established  between  the  anterior 
and  posterior  sub-arachnoid  spaces.  All  these  spaces  contain  serum  in  the  natural 
state,  and  coagulable  lymph  in  some  cases  of  inflanmiation  of  the  sub-arachnoid  cellular 
tissue. 

The  arachnoid  is  arranged  in  a  uniform  manner  in  reference  to  all  the  nerves  situated 
at  the  base  of  the  brain  ;  it  passes  over  their  lower  surface,  and  therefore  holds  them 
firmly  against  the  under  surface  of  the  brain  ;  but  where  these  nerves  are  separated 
from  the  brain  it  furnishes  a  tubular  prolongation  around  each,  and  again  leaves  them 
as  they  are  about  to  enter  the  foramina  in  the  base  of  the  scull,  and  is  reflected  upon  the 
dura  mater. 

Upon  the  upper  surface  of  the  brain,  the  arachnoid  dips  into  the  median  fissure,  and  is 
reflected  from  one  hemisphere  to  the  other  immediately  below  the  free  margin  of  the  falx 
cerebri ;  and  as  this  margin  is  nearer  to  the  corpus  callosum  behind  than  in  front,  it  fol- 
lows that  the  anterior  portions  of  the  two  hemispheres  are  in  contact  with  each  other 
for  a  certain  distance,  or,  rather,  they  are  merely  separated  by  the  pia  mater. 

The  cerebral  arachnoid  adheres  intimately  to  the  arachnoid  of  the  dura  mater,  along 
the  sides  of  the  superior  longitudinal  sinus,  by  means  of  the  tubular  prolongations  which 
it  forms  around  the  cerebral  veins  that  enter  that  sinus.  This  adhesion  is  also  strength- 
ened by  the  granular  bodies  called  the  glands  of  Pacchioni,  which,  as  we  have  already 
stated,  lie  in  the  substance  of  the  dura  mater. 

Moreover,  on  the  convex  surface,  as  well  as  upon  the  base  of  the  brain,  the  arachnoid, 
in  covering  this  organ,  passes,  like  a  bridge,  from  one  convolution  to  another,  never  dip- 
ping into  the  intermediate  sulci. 

The  cellular  tissue,  which  unites  the  arachnoid  to  the  pia  mater,  is  of  a  serous  nature 
and  extremely  delicate,  so  that  the  two  membranes  can  be  easily  separated,  excepting 
in  cases  of  inflammation.  When  air  is  blown  beneath  the  arachnoid,  the  extreme  tenu- 
ity of  this  cellular  tissue  becomes  evident :  it  is  very  frequently  infiltrated  with  a  serous 
fluid. 

The  sub-arachnoid  cellular  tissue  never  contains  any  fat.  The  fat  which  Ruysch, 
Haller,  and  other  anatomists  say  they  have  observed,  must  have  been  that  yellowish, 
gelatiniform  lymph  so  commonly  met  with  in  cases  of  inflammation.* 

In  some  parts  the  arachnoid  is  lined  by  a  fibrous  tissue,  which  gives  it  great  strength. 
This  fibrous  tissue,  which  may  be  regarded  as  a  prolongation  of  the  neurilemma  of  the 
spinal  cord,  is  especially  distinct  in  the  great  furrows  of  the  brain.    Thus  we  find  it 

*  I  onoe  found  in  an  old  woman  an  adipose  cyst,  about  the  size  of  a  small  grape,  arising  by  a  very  thin  ped- 
icle from  the  upper  surface  of  the  pituitary  body. 


THE  PARIETAL  LAYER  OP  THE  ARACHNOID.  689 

around  the  great  anterior  sub-arachnoid  space,  where  it  constitutes,  as  it  were,  a  very 
strong  fibrous  band,  which  surrounds  the  arterial  circle  of  Willis,  situated  at  the  base  of 
the  brain  ;  it  also  retains  the  different  parts  of  the  brain  in  their  relative  positions,  even 
when  that  organ  is  removed  from  the  cranium,  and  is  laid  with  its  base  uppermost. 
The  Parietal  Layer  of  the  Arachnoid. 

The  internal  surface  of  the  dura  mater  is  lined  with  a  very  delicate  and  closely-ad- 
herent serous  membrane,  which,  owing  to  these  two  qualities,  for  a  long  time  escaped 
the  notice  of  anatomists.  It  was  only  by  reasoning  analogically  from  the  structure  of 
all  other  serous  membranes,  that  Bichat  was  led  to  enter  upon  the  inquiry  which  ended 
in  the  discovery  of  the  parietal  portion  of  the  arachnoid.  This  portion  is  quite  distinct 
from  the  internal  layer  of  the  dura  mater,  the  existence  of  which  we  have  admitted 
with  several  anatomists.  Upon  a  mere  inspection,  we  should  say  that  it  does  not  exist, 
because,  from  its  transparency,  the  fibrous  bundles  of  the  dura  mater  can  be  seen  as  dis- 
tinctly as  if  they  were  not  covered.  But  if  a  very  superficial  incision  be  made  upon  the 
inner  surface  of  the  dura  mater,  some  extremely  thin  shreds  may  be  detached  by  the 
aid  of  the  forceps.  Lastly,  ecchymosis  not  unfrequently  occurs  between  the  dura  mater 
and  the  arachnoid.*  Ossilic  deposites  in  the  dura  mater,  especially  those  found  in  the 
falx  cerebri,  being  found  beneath  the  arachnoid,  sometimes  enable  us  to  detach  this  lat- 
ter membrane  in  the  most  distinct  manner. 

It  still  remains,  however,  to  describe  the  mode  in  which  the  parietal  and  cerebral  por- 
tions of  the  arachnoid  become  continuous  with  each  other.  It  has  been  stated  that  the 
arachnoid  membrane  forms  tubular  prolongations  around  each  of  the  nerves  which  are 
given  off  from  the  base  of  the  brain,  and  around  each  of  the  veins  which  enter  the  dif- 
ferent sinuses  ;  these  prolongations  just  enter  the  fibrous  canals  formed  by  the  dura 
mater  for  these  nerves  and  veins,  and  almost  immediately  terminate  by  being  reflected 
upon  the  dura  mater  itself ;  so  that  the  arachnoid  forms  a  sort  of  cul-de-sac  around  the 
cranial  orifice  of  each  fibrous  sheath  of  the  dura  mater.  In  order  to  see  the  funnel- 
shaped  prolongations  of  the  arachnoid,  it  is  convenient  to  examine  them  when  the  brain 
is  being  lifted  up  from  before  backward,  in  order  to  expose  and  divide  the  nerves  which 
are  attached  to  the  base  of  the  scuU.  The  tubular  prolongations  being  then  dragged 
upon,  they  become  very  distinct.  Not  unfrequently,  the  development  of  adventitious 
false  membrane  on  the  base  of  the  brain  also  extends  along  these  prolongations. 

The  arachnoid  does  not  enter  into  the  interior  of  the  ventricles,  below  the  posterior 
border  of  the  corpus  callosum.  The  arachnoid  canal,  called  the  canal  of  Bichat,  does  not 
exist,  but  it  is  formed  by  the  very  experiment  made  to  demonstrate  it.  The  following 
is  the  statement  of  Bichat  regarding  this  alleged  canal : 

"  The  brain  being  exposed  from  behind  and  allowed  to  remain  in  its  natural  position, 
the  back  part  of  each  posterior  lobe  is  to  be  raised,  and  drawn  gently  outward  ;  the  ve- 
nae Galeni  are  then  seen  emerging  from  the  canal  by  which  they  are  embraced,  and  the 
oval  orifice  of  which  is  now  very  apparent.  Sometimes,  however,  the  margin  of  this 
orifice  embraces  the  veins  so  closely,  that  it  can  only  be  recognised  by  a  small  fissure 
on  each  side,  and  the  parts,  at  first  sight,  would  appear  to  be  continuous.  If  a  probe  be 
then  glided  from  behind  forward  along  these  vessels,  and  when  it  has  penetrated  a  short 
distance,  if  it  he  turned  all  round  the  veins  it  will  destroy  the  adhesions,  and  the  opening  vnH 
become  very  evident. 

"  In  order  to  be  convinced  that  this  opening  leads  into  the  middle  ventricle  of  the 
brain,  a  grooved  director  must  be  introduced  below  the  venae  Galeni  and  pushed  gently 
forward  :  it  will  enter  the  ventricle  without  difficulty.  The  corpus  callosum  and  the  for- 
nix are  then  to  be  removed,  and  the  velum  interpjjsitum  left  untouched.  Next,  dividing 
the  velum  on  the  director,  the  membrane  will  be  found  to  be  smooth  and  polished  in  the 
whole  of  its  course,  and  nowhere  lacerated  by  the  introduction  of  the  director.  Occa- 
sionally some  resistance  is  experienced  to  the  entrance  of  the  director,  which  may  even  be  com- 
pletely arrested :  this  depends  upon  the  fact  that  the  veins  which  enter  the  vena  Galeni  inter- 
lace in  all  directions  within  the  canal,  so  as  to  form  a  network,  which  arrests  the  instrument. 
If  this  be  the  case,  it  should  be  withdrawn,  and,  in  order  to  demonstrate  the  communi- 
cation, some  mercury  should  be  poured  into  the  external  opening,  and,  by  inclining  the 
position  of  the  head,  this  fluid  will  flow  into  the  middle  ventricle.  Air  blown  into  the 
canal  will  also  enter  that  ventricle,  and  will  pass  from  it  into  the  lateral  ventricles  through 
the  openings  behind  the  anterior  pillars  of  the  fornix.  If  the  fornix  be  removed,  and 
the  velum  be  exposed,  the  latter  will  be  seen  to  be  elevated  each  time  that  the  air  is 
blown  in. 

"  The  internal  orifice  of  this  communicating  canal  is  at  the  lower  part  of  the  velum 
interpositum ;  in  order  to  see  it,  this  membrane  must  be  reflected  backward,  either  with 
the  fornix,  the  under  surface  of  which  it  covers,  or  after  it  has  been  separated  fram  that 
part  of  the  brain.     The  pineal  gland  which  adheres  to  the  velum  is  also  to  be  turned 

*  As  to  the  collections  of  blood  which  are  said  to  have  been  met  with  between  the  arachnoid  and  the  dnra 
mater,  M.  Baillarget  has  clearly  shown,  in  several  preparations  which  he  presented  to  the  Anatomical  Soci- 
ety, that  the  supposed  laver  of  arachnoid  is  a  newly- formed  membrane,  having  all  the  appearances  of  a  serous 
membrane. 

4  S 


690  '  VEUROLOGY. 

back  ;  below  and  in  front  of  this  gland  is  then  seen  a  row  of  cerebral  granulations,  ar- 
ranged in  the  form  of  a  triangle,  having  its  point  turned  forward.  The  internal  orifice 
of  the  canal  of  the  arachnoid  is  at  the  base  of  this  triangle." 

Now,  if  we  make  the  dissection  described  by  Bichat,  it  is  easy  to  see  that  there  exists 
at  the  back  part  of  the  brain,  below  the  corpus  callosum,  a  circular  or  oval  opening,  lead- 
ing into  a  sort  of  cul-de-sac,  which  is  of  variable  depth,  and  is  formed  by  the  reflection 
of  the  arachnoid  around  the  venae  Galeni :  it  is  seen,  also,  that  the  bottom  of  this  cul-de- 
sac  may  be  easily  lacerated  by  a  blunt  probe,  which  may  then  be  passed  beneath  th< 
velum  interpositum,  as  Bichat  has  pointed  out ;  but  it  is  through  an  artificial  canal. 
Moreover,  if  a  coloured  liquid  be  injected  into  the  ventricles,  it  can  never  be  made  to 
escape  through  this  imagined  canal  of  Bichat ;  and  so,  on  the  other  hand,  if  a  liquid  be 
thrown  into  the  orifice  of  this  canal,  it  never  enters  the  third  ventricle :  mercury  enters 
only  by  lacerating  the  parts  ;  and  the  same  is  the  case  with  air.  Analogy,  which  has 
so  often  conducted  Bichat  to  beautiful  and  grand  discoveries,  has,  therefore,  misled  him 
in  this  particular. 

Since,  then,  the  arachnoid  canal  of  Bichat  does  not  exist,  it  will  be  necessary  to  de- 
termine how  the  ventricles  communicate  with  the  external  arachnoid  cavity.  This 
question  we  shall  discuss  presently.* 

The  Spinal  Portion  of  the  Arachnoid. 
The  spinal  cord,  besides  its  own  proper  investment,  is  covered  by  a  transparent  mem- 
brane of  extreme  tenuity,  and  only  to  be  demonstrated  properly  by  raising  it  with  the 
forceps,  or  by  subjecting  it  to  the  mode  of  preparation  above  described  :  this  is  the  vis- 
ceral layer  of  the  spinal  portion  of  the  arachnoid. 

The  visceral  layer  (b,  fig.  266,  A  B)  forms  a  membranous  sheath,  which  is  much  larger 
than  the  spinal  cord  (*) ;  hence  it  is  named  the  loose  arachnoid.  It  is 
prolonged  around  the  bundle  of  nerves  called  the  cauda  equina,  and  forms 
around  each  nerve  a  funnel-shaped  sheath,  which  terminates  in  a  cul- 
de-sac  at  the  corresponding  inter-vertebral  foramen,  by  being  reflected 
upon  the  inner  surface  of  the  fibrous  sheath  formed  for  the  nerve  by  the 
dura  mater  (see^^.  266,  B). 

There  exists,  then,  between  the  spinal  cord  and  the  visceral  portion 
of  the  arachnoid  a  considerable  space  (e,  fig.  266,  A  B),  which  can  be 
best  displayed  by  inflating  it,  or  injecting  it  with  some  liquid.  This 
space,  as  we  shall  immediately  show,  contains  a  serous  fluid. 

We  have  seen  that,  opposite  the  median  excavation  at  the  base  of 
the  brain,  the  arachnoid  adheres  to  the  cerebral  pia  mater  only  by  means 
of  long  fibrous  filaments.  The  spinal  arachnoid  also  adheres  to  the  proper  covering  of 
the  cord  by  means  of  fibrous  filaments  ;  but  in  no  part  does  there  exist  any  delicate  sub- 
arachnoid cellular  tissue,  like  that  found  beneath  the  cerebral  arachnoid.! 

Another  peculiarity  in  the  visceral  layer  of  the  spinal  portion  of  the  arachnoid  is  this, 
that  it  adheres  to  the  parietal  layer  in  a  number  of  points. 

The  parietal  layer  (a)  of  the  spinal  portion  of  the  arachnoid  is  arranged  precisely  in  the 
same  manner  as  the  parietal  layer  of  arachnoid  in  the  scull.  It  becomes  continuous 
with  the  visceral  layer  opposite  the  sheaths  which  are  formed  by  the  latter  around  the 
spinal  nerves. 

The  Sub-arachnoid  Fluid. 

There  exists  around  the  spinal  cord  a  serous  fluid,  in  quantity  suflicient  to  occupy  the 
interval  left  between  the  cord  and  the  dura  mater  :  this  fluid  is  seated  in  the  sub-arach- 
noid space  (e).  A  similar  fluid  exists  in  the  ventricles  of  the  brain  and  in  the  sub-arach- 
noid cellular  tissue,  and  fills  the  free  spaces  of  the  cranial  cavity.t 

The  existence  of  the  sub-arachnoid  fluid  was  pointed  out  by  Haller  (Elcmcnta  fhysi- 
ologicB,  t.  iv.,  87),  and  most  explicitly  and  completely  demonstrated  by  Cotugno  (I>e  ischi- 
ade  nervosa  commcntarium),  but  the  fact  was  neglected  by  anatomists,  and  the  fluid  re- 
garded by  some  as  the  result  of  cadaveric  exudation,  and  by  others  as  that  of  a  morbid 
action.  The  existence  of  this  fluid  has  been  again  confirmed  by  M.  Magendie,  who, 
moreover,  has  clearly  proved  that  it  is  seated  in  the  sub-arachnoid  tissue. 

In  order  to  prove  the  existence  of  the  sub-arachnoid  fluid,  or  cephi  o-iaunoian  nuid 

*  [The  existence  of  the  canal  of  Bichat  is  admitted  by  Arnold,  a  recent  authority.  Perhaps  the  opposite 
statements  of  anatomists  concerning  this  canal  may  depend  on  the  fact  that  the  canal  itself,  though  originally 
present,  is  sometimes  closed  subsequently,  and  at  other  times  remains  open.] 

t  [The  spinal  sub-arachnoid  space  is  divided  behind  by  a  thin,  and,  in  some  parts,  cribriform  longitudinal 
septum,  which  extends  from  the  loose  arachnoid  to  the  posterior  median  fissure  of  the  cord.  This  space  is 
probably4i>ied  throughout  by  a  serous  membrane,  which  contains  the  rachidian  fluid,  and  which  might  be 
named  the  internal  arachnoid.  The  septum  just  mentioned  may  be  supposed  to  consist  of  two  layers  of  thJB 
membrane  reflected  from  the  loose  arachnoid  to  the  cord,  and  having  the  same  relation  to  it  as  the  mesentery 
has  to  the  intestine  ;  and  the  membrane  itself  may  be  conceived  to.be  prolonged  through  the  foramen  described 
by  Magendie  at  the  Ijottom  of  the  fourth  ventricle  (see  p.  718),  so  as  to  form  the  lining  membrane  of  the  fourth, 
third,  and  lateral  ventricles ;  and,  farther,  in  case  of  the  existence  of  the  foramen  of  Bichat,  to  become  con- 
tinuous with  the  external  or  true  arachnoid  through  that  foramen.] 


THE    SUB- ARACHNOID   FLUID.  691 

of  Magendie,  it  is  necessary  to  open  the  lumbar  region  of  the  spinal  canal  in  a  certain 
number  of  subjects.  If  an  incision  be  very  carefully  made  through  the  dura  mater,  it 
will  be  seen  that  the  serous  fluid  raises  the  visceral  layer  of  the  arachnoid,  so  as  to  make 
it  protrude  like  a  hernia  through  the  incision  :  if  this  layer  of  arachnoid  be  then  divided, 
the  liquid  will  escape.  Cotunni,  who  performed  this  experiment  upon  tw^enty  subjects, 
collected  from  four  to  five  ounces  of  fluid  in  each  case. 

To  the  objection  that  this  fluid  is  found  after  death,  but  does  not  necessarily  exist  in 
the  living  subject,  we  may  answer  thus  :  There  is  a  space  between  the  spinal  cord  and 
the  dura  mater,  and  the  brain  itself  does  not  exactly  fill  the  cranial  cavity.  Now  in  no 
part  of  the  animal  body  does  there  exist  any  vacuum ;  the  spaces  between  the  solids  are 
always  filled  either  with  liquids  or  gaseous  fluids.  But  if  it  be  said  that  in  this  situation 
the  space  is  filled  by  a  serous  vapour,  the  elasticity  of  which  might  establish  an  equilib- 
rium with  the  external  air,  it  may  be  replied,  that  this  vapour  would  not  be  sufficient  to 
produce  so  large  a  quantity  of  fluid  as  is  found  in  the  spinal  canal. 

Moreover,  all  these  objections,  and  also  the  supposition  that  the  brain  and  spinal  cord 
may  be  smaller  after  death  than  during  life,  are  overthrown  by  the  following  experiment. 
If  the  posterior  cervical  muscles  be  divided  in  a  living  dog,  at  their  occipital  attachments, 
the  posterior  occipito-atlantoid  ligament  will  be  exposed.  The  parts  being  weU  cleansed 
from  blood,  the  ligament  must  be  cut  away,  layer  by  layer,  with  a  scalpel  held  flat  against 
it.  The  ligaments  will  scarcely  be  cut  through  before  a  small  hernial  protrusion,  con- 
taining a  fluid,  will  be  seen ;  this  consists  of  the  visceral  arachnoid  raised  by  the  rush 
of  fluid.  If  a  crucial  incision  be  then  made  in  the  occipito-atlantoid  ligament,  by  the  aid 
of  a  director,*  a  fluid  as  limpid  as  distilled  water  will  be  seen  beneath  the  visceral  layer 
of  the  arachnoid,  which  fluid  is  agitated  by  two  kinds  of  motion,  one  of  which  is  isochro- 
nous with  the  pulse,  and  the  other  with  the  respiratory  movements.  If  the  arachnoid 
be  next  punctured,  the  fluid  will  immediately  escape  in  jets,  and  its  quantity  may  be  as- 
certained. 

The  difficulty  of  not  wounding  the  visceral  layer  of  the  arachnoid  explains  why,  until 
recently,  it  was  thought  that  the  spined  fluid  was  contained  within  the  arachnoid  cavity 
{c,jig.  266),  i.  e.,  between  the  two  layers  of  the  arachnoid  membrane,  although  most  ob- 
servers had  noticed  that  the  serous  fluid  in  the  cranium  occupied  the  sub-arachnoid  cel- 
lular tissue.  It  follows,  therefore,  that  besides  the  fluid  which  is  exhaled  from  the  free 
surface,  i.  e.,  into  the  cavity  of  the  arachnoid,  a  certain  quantity  of  a  similar  fluid  fills  up 
the  areolar  tissue  of  the  sub-arachnoid  space :  in  this  respect  the  arachnoid  differs  es- 
sentially from  other  serous  membranes,  all  of  which  pour  their  secretions  into  their  cav- 
ities, and  not  into  the  subjacent  cellular  tissue. 

This  peculiarity  depends  simply  upon  the  non-adhesion  of  the  arachnoid  to  the  spinal 
cord ;  it  may  be  stated  as  a  law,  that  serous  membranes  exhale  almost  indifferently 
from  either  their  internal  or  their  external  surface,  when  the  latter  surface  is  not  adhe- 
rent. The  arachnoid  exhales  a  fluid  from  both  surfaces  ;  a  certain  quantity  of  fluid  is 
rather  frequently  found  between  its  two  layers  ;  and  although,  in  acute  inflammations, 
the  deposite  of  purulent  matter  or  of  false  membranes  most  generally  takes  place  in  the 
sub-arachnoid  cellular  tissue,  yet  these  morbid  products  are  not  unfrequently  found  in 
the  cavity  of  the  spinal  arachnoid  itself 

The  sub-arachnoid  fluid  exists  not  only  in  the  vertebral  canal,  but  also  within  the  cra- 
nium, in  which  it  fills  up  all  the  spaces  between  the  brain  and  the  dura  mater. 

Now  these  spaces  are  subject  to  much  variety  in  size  in  different  individuals,  or  from 
age  or  from  disease  :  thus,  in  atrophy  of  the  brain  and  spinal  cord,  from  old  age  or  dis- 
ease, the  interval  between  the  dura  mater  and  the  cerebro-spinal  axis  is  augmented,  and 
the  quantity  of  fluid  increases  in  the  same  proportion. 

The  quantity  of  the  sub-arachnoid  fluid  is  in  a  direct  ratio  with  the  progress  of  age  ; 
in  aged  lunatics,  in  whom  the  convolutions  of  the  brain  are  much  atrophied,  the  quanti- 
ty of  this  fluid  contained  within  the  cavity  of  the  cranium  is  very  great,  t 

The  sub-arachnoid  fluid  in  the  cranium  is  not  distributed  equally  around  the  brain,  but 
is  chiefly  seated  at  its  base.  In  order  to  show  this  fluid,  it  is  merely  necessary  to  raise 
up  the  brain  carefully  from  before  backward,  when  it  will  be  seen  distending  all  the  fun- 
nel-shaped prolongations  formed  by  the  arachnoid  around  the  nerves,  and  it  will  escape 
as  soon  as  the  membrane  is  divided. 

As  regards  quantity,  the  sub-arachnoid  fluid  at  the  base  of  the  brain  and  the  fluid  of 
the  ventricles  are  always  directly  proportioned  to  each  other,  but  are  inversely  propor- 
tioned to  the  sub-arachnoid  fluid  upon  the  convex  surface  of  the  brain.  Upon  opening 
the  head  of  infants  who  have  died  from  acute  ventricular  hydrocephalus,  we  sometimes 

*  It  is  highly  important  to  make  the  transverse  incision  very  short,  in  order  to  avoid  injuring-  the  very  large 
vertebral  veins  ;  for  if  these  vessels  be  cut,  the  hemorrhage  will  be  so  abundant  as  to  prevent  the  continuation 
of  the  experiment. 

t  None  of  these  facts  escaped  the  notice  of  Cotugno : 

"  Nee  tantnm  'axe  aqua  complens  ab  occipite  ad  usque  imum  os  sacrum,  tubum  dun-e  matris  .  .  .  sed  et  u 
ipso  redundat  calcarise  cavo  omniaque  complet  intervalla  quae  inter  cerebrum  et  durse  matris  ambitum  )nven> 
antur  ....  quantum  autem  magnitudinis  cerebrum  in  his  perdit,  tantum  a  contactu  subtrahitur  durs  matns 
et  quidquid  loci  decrescendo  reliquit,  aquosus  vapor  coUectus  lotum  adimplet." — (Op.  cit.,  p.  11.  12.) 


692  NEUROLOGY. 

find  the  convex  surface  of  the  brain  dry,  and,  as  it  were,  adhesive.  It  is  of  importance 
to  determine  whether  the  cavities  containing  the  cephalic  and  the  spinal  fluids  commu- 
nicate with  each  other.  There  can  be  no  doubt  that  the  sub-arachnoid  spaces  of  the 
brain  communicate  with  the  sub-arachnoid  space  around  the  spinal  cord ;  but  do  the 
cavities  of  the  ventricles  communicate  with  the  sub-arachnoid  space  1 

Haller  admitted  that  the  fluid  could  flow  from  the  ventricles  into  the  spinal  canal,  and 
he  believed  that  this  was  effected  by  a  communication  between  the  ventricles  and  the 
cavity  of  the  arachnoid  itself*  Cotugno  expresses  the  same  opinion  still  more  distinct- 
ly. Both  Haller  and  Cotugnot  thought  that  this  communication  occurred  at  the  bottom 
of  the  fourth  ventricle,  but  they  neither  indicated  the  exact  situation,  nor  the  mode  in 
which  it  is  effected.  M.  Magendie  has  pointed  out  that  it  occurs  at  this  very  spot,  near 
the  point  of  the  calamus  scriptorius.  Bichat  stated  that  the  communication  between  the 
ventricles  and  the  arachnoid  cavity  was  at  the  so-called  canal  of  Bichat.  The  mode  in 
which  the  fourth  ventricle  communicates  with  the  sub-arachnoid  space  will  be  much 
better  understood  if  stated  in  our  description  of  that  ventricle,  t 

Uses  of  the  Arachnoid  and  of  the  Sub-arachnoid  Fluid. 

Uses  of  the  Arachnoid. — Like  all  serous  membranes,  the  essential  use  of  the  arachnoid 
is  to  lubricate  the  surface  of  the  brain  and  spinal  cord,  and  thus  facilitate  their  move- 
ments. No  other  membrane  more  completely  fulfils  such  a  use,  for  the  arachnoid  is 
moistened  in  both  its  external  and  internal  surfaces.  It  would,  in  fact,  be  an  error  to 
suppose  that  the  serous  secretion  is  poured  out  solely  by  that  surface  of  the  arachnoid 
which  is  turned  towards  the  pia  mater :  the  fluid  is  exhaled  upon  its  internal  surface 
also,  as  in  all  other  serous  membranes,  so  that  we  sometimes  find  serum,  pus,  and  false 
membranes  in  the  cavity  of  the  arachnoid  itself 

Uses  of  the  Sub-arachnoid  Fluid. — The  sub-arachnoid  fluid  forms  a  sort  of  bath  around 
the  spinal  cord,  which  effectually  protects  it  during  the  various  motions  of  the  vertebral 
column.  It  might  be  said  that  the  spinal  cord,  being,  in  reference  to  its  delicacy,  in  con- 
ditions somewhat  analogous  to  those  of  the  foetus  in  utero,  requires  a  similar  method  of 
protection ;  and  in  this  point  of  view  the  sub-arachnoid  fluid  exactly  represents  the  liquor 
of  the  amnios. 

As  to  the  other  uses  which  have  been  attributed  to  it,  they  are  all  more  or  less  hypo- 
thetical. 

If  we  open  the  spinal  canal  of  a  dog,  between  the  atlas  and  the  occipital  bone,  some 
fluid  will  immediately  gush  out ;  air  is  drawn  in,  which  is  forced  out  in  bubbles  during 
expiration,  and  again  enters  during  inspiration.  If  the  animal  be  then  left  to  himself,  he 
will  stagger  like  a  drunken  man ;  he  will  crouch  into  a  comer,  and  remain  in  a  drowsy 
state  for  some  hours.  On  the  next  day  he  will  walk  about  again  perfectly  well.  I  have 
repeated  this  operation  several  times  upon  the  same  dog,  until  at  last  he  became  accus- 
tomed to  it,  at  least  as  far  as  regards  the  physiological  effects  resulting  from  the  remo- 
val of  the  fluid,  by  which  means  the  slight  pressure  usually  exercised  upon  the  spinal 
cord  was  removed. 

The  Pia  Mater. 

The  pia  mater  is  the  innermost  of  the  three  membranes  of  the  encephalon  and  spinal 
cord.  It  consists  of  an  extremely  delicate  membrane,  or,  rather,  of  a  vascular  network, 
which  inunediately  invests  the  nervous  axis,  and  which  may  be  regarded  as  the  nutri- 
tious membrane  of  the  parts  that  are  covered  by  it.  In  fact,  the  arterial  vessels  divide 
into  an  infinite  number  of  branches  within  this  membrane  before  they  enter  the  nervous 
substance,  and  so,  also,  the  veins  which  pass  out  from  the  brain  and  spinal  cord  unite 
into  small,  and  then  into  larger  vessels,  which  form  part  of  this  same  network.  These 
vessels  are  supported  by  a  very  delicate  serous  cellular  tissue  :  to  this  is  added,  in  some 
regions,  a  certain  amount  of  fibrous  tissue,  which  converts  the  membrane  into  a  very 
strong  fibrous  structure,  having  all  the  characters  of  the  neurilemma,  or  proper  invest- 
ment of  the  nerves. 

The  characters  of  the  spinal  portion  of  the  pia  mater  are  so  distinct  from  those  of  the 
cranial  portion,  that  it  will  be  better  to  postpone  the  description  of  the  former  until  we 
are  treating  of  the  spinal  cord,  of  which  it  constitutes  the  proper  covering. 

The  Cranial  Portion  of  the  Pia  Mater. 
This  portion,  or  the  cerebral  pia  mater,  does  not  merely  enclose  the  brain  like  the  arach- 
noid, but  dips  into  the  sulci  or  anfractuosities  on  its  external  surface,  and  penetrates  into 
the  interior  of  the  ventricles.     That  portion  of  the  pia  mater  which  invests  the  brain  is 

*  "  Qua  prodit  de  ventriculo  aqua,  facili  in  medullse  spinalis  circumjectum  spatium  etiam  parat ;  earn  aquam 
enim  difficulter  omnino  in  tertium  ventriculum  et  ad  infundibulum  redderet,  quoad  perpendiculum  oportet  a»- 
cendere  (Haller,  torn,  iv.,  sect.  3,  p.  77)  .  .  .  Non  dubito  quin  coUecta  ex  ventriculis  cerebri  aqua  eo  descen- 
dere  possit." — (Ibid.,  sect.  3,  p.  87.) 

t  "  His  spinae  aquis  eas  etiam  subinde  commisceri,  quas,  sive  a  majoribos  cerebri  ventriculis  per  lacunar  et 
Sylvii  aqueductum,  sive  a  propriis  exhalantibus  arteriis,  cerebelli  ventriculus  accipiat ;  cujus  positio  perpen- 
diculata  et  via  ad  spine  cavum  satis  patens  defluxum  liumoris  in  spinam  manifest!  persuadent." — {Cotugno, 
p.  18,  19.)  t  See  note,  p.  960. 


THE    EXTERNAL   CEREBRAL    PIA    MATER,   ETC.  693 

called  the  external  pia  mater,  and  that  which  is  continued  into  the  ventricles  is  denomi- 
nated the  internal  pia  mater. 

The  internal  pia  mater  cannot  be  satisfactorily  studied  until  the  internal  conformation 
of  the  brain  is  understood,  and  it  will  therefore  be  described  together  with  the  ventricles. 

The  External  Cerebral  Pia  Mater. 

Dissection. — At  the  base  of  the  brain,  the  pia  mater  is  naturally  separated  from  the 
arachnoid  by  a  considerable  space,  which  is  occupied  by  the  sub-arachnoid  fluid  ;  but  it 
is  easy  to  separate  these  two  membranes  everywhere  by  introducing  air  or  water  be- 
tween them.  The  arachnoid  may  be  easily  distinguished  from  the  pia  mater  in  cases 
of  serous  or  purulent  infiltration  into  the  sub-arachnoid  cellular  tissue. 

The  external  pia  mater  is  subjacent  to  the  arachnoid,  and  is  connected  with  it  by  a  very 
delicate  serous  cellular  tissue  ;  it  not  only  covers  the  free  surface  of  each  convolution, 
but  also  dips  into  the  adjacent  sulci ;  it  passes  down  on  one  side  of  a  sulcus,  and  then, 
being  reflected  upon  the  other,  is  continued  over  the  free  surface  of  the  next  convolu- 
tion, and  so  on.  It  follows,  therefore,  that  this  part  of  the  pia  mater  is  in  contact  with 
itself  to  a  great  extent ;  and  also  that  its  superficies  is  much  larger  than  that  of  the 
arachnoid,  so  that  if  the  brain  could  be  unfolded,  as  Gall  supposed,  its  surface  would  be 
entirely  covered  by  the  pia  mater.  These  remarks  apply  equally  to  the  pia  mater  of  the 
cerebellum,  for  every  one  of  the  numerous  leuninae  of  that  organ  is  covered  on  each  side 
by  a  fold  of  the  pia  mater. 

The  internal  surface  of  the  pia  mater  is  in  contact  with  the  brain,  and  is  united  to  it 
by  innumerable  vessels,  which  penetrate  into  the  substance  of  that  organ.  This  adhe- 
sion, however,  is  such,  that  the  pia  mater  can  generally  be  detached  without  injuring 
the  surface  of  the  brain. 

I  do  not  think,  however,  with  some  pathologists,  that  the  adhesion  of  this  membrane 
to  such  a  degree  that  it  cannot  be  removed  without  injuring  the  substance  of  the  brain 
is  any  evidence  of  disease.* 

For  displaying  the  vessels  which  pass  into  the  substance  of  the  brain  from  the  pia 
mater,  an  asphyxiated  subject  is  very  well  adapted.  But  an  injected  condition  of  these 
vessels  may  be  produced  by  allowing  the  head  of  the  subject  to  hang  down  for  some 
hours.  The  pia  mater  will  then  be  not  only  black  from  its  congested  state,  but  it  will  be 
infiltrated  with  serum  ;  and  if  it  be  detached  slowly,  an  immense  number  of  vascular 
filaments,  looking  like  hairs,  will  be  seen  emerging  from  the  substance  of  the  brain,  re- 
markable for  their  extreme  tenuity  and  length,  and  for  having  no  anastomoses.  Some 
drops  of  blood  will  indicate  the  points  upon  the  surface  of  the  brain  from  which  the  ves- 
sels escape,  and  which,  when  examined  through  a  lens,  prove  to  be  foramina. 

The  use  of  the  pia  mater  is  connected  solely  with  the  circulation  of  blood  through  the 
brain.  This  membrane  affords  to  the  vessels  a  very  large  surface,  on  which  the  arteries 
divide  into  their  capillary  branches,  and  the  veins  unite  into  their  larger  and  larger 
trunks.  According  to  my  observations,  five  sixths  of  the  vessels  of  the  pia  mater  belong 
to  the  venous  system. 

The  pia  mater  is  the  nutritious  membrane  of  the  brain,  and  may  thus  be  regarded  as 
its  neurilemma. 

It  will  afterward  be  seen  that  the  internal  pia  mater  is  connected  with  the  arteries 
and  veins  of  the  walls  of  the  ventricles,  ^ust  as  the  external  pia  mater  is  with  the  ex 
ternal  vessels. 


THE  SPINAL  CORD  AND  THE  MEDULLA  OBLONGATA. 

General  View  of  the  Cord — its  Limits  and  Situation — the  Ligamentum  Denticulafum. — Size 
of  the  Spinal  Cord — Form,  Directions,  and  Relations — the  Cord  in  its  proper  Membrane — 
the  proper  Membrane,  or  Neurilemma  of  the  Cord — the  Cord  deprived  of  its  proper  Mem- 
brane.— Internal  Structure  of  the  Cord — Sections — Examination  by  Means  of  Water — and 
when  hardened  in  Alcohol — the  Cavities  or  Ventricles  of  the  Cord. — The  Medulla  Oblonga- 
ta— Situation — External  Conformation — Anterior  Surface,  the  Anterior  Pyramids,  and  the 
Olivary  Bodies — the  Posterior  Surface — the  Lateral  Surfaces — the  Internal  Structure — 
Sections — Examination  by  Dissection,  and  under  Water. — Development  of  the  Spinal 
Cord. — Development  of  the  Medulla  Oblongata. — Comparative  Anatomy  of  the  Spinal 
Cord. — Comparative  Anatomy  of  the  Medulla  Oblongata. 

The  spinal  cord  (fzvelog  jidxiTTig,  medulla  spinalis,  a  b  c,  fig.  268)'is  that  white,  round- 
ish, symmetrical,  nervous  trunk,  which  occupies  the  spinal  canal ;  it  is  continuous  with 
the  encephalon,  of  which  it  has  been  alternately  considered  the  origin  and  the  termina- 
tion. It  is  called  the  medulla,  in  consequence  of  a  rude  analogy  between  it  and  the  mar- 
row of  the  long  bones,  in  regard  to  its  situation  and  consistence.     Chaussier  has  sub- 

*  In  some  cases  the  membranes  are  so  dry  that  the  pia  mater  cannot  be  removed  without  tearing  the  sub 
itance  of  the  brain,  even  when  that  organ  is  perfectly  healthy. 


094  NEUKOLOGY. 

stituted  for  this  term  the  title  of  racfddian  prolongation,  but  the  generally  received  name 
of  spinal  marrow,  which  can  give  rise  to  no  error,  might  be  retained.* 

The  Extent  and  Situation  of  the  Spinal  Cord. 

Authors  are  not  agreed  as  to  the  superior  limit  of  the  spinal  cord.  The  natural  limit 
is  evidently  at  the  groove,  between  the  medulla  oblongata  (a.  Jig.  268)  and  the  pons 
Varolii  (e),  which  groove,  on  account  of  the  great  size  of  the  pons  in  man,  is  much  more 
distinctly  marked  in  him  than  in  those  vertebrated  animals  in  which  the  pons  is  also 
found. 

The  spinal  cord  is  situated  in  the  median  line,  at  the  back  part  of  the  trunk ;  it  is  be- 
hind the  organs  of  digestion,  circulation,  and  respiration,  t 

The  vertebral  column,  the  dura  mater,  the  arachnoid,  and  the  pia  mater  form  a  fourfold 
sheath  for  the  spinal  cord  ;  the  first  being  osseous  ;  the  second,  fibrous  ;  the  third,  serous ; 
and  the  fourth,  or  proper  sheath,  both  fibrous  and  vascular ;  this  last-named  membrane 
is  accurately  adapted  to  the  cord,  so  as  to  support  it,  and  gently  compress  it  on  all  sides. 

The  spinal  cord  is  not  suspended  freely  in  the  vertebral  canal,  but  is  attached  on  each 
side  by  a  ligament  called  the  ligamentum  denticulatum. 

The  Ligamentum  Denticulatum. 
The  ligamentum  denticulatum  (c  c,  fig.  267),  so  called  from  the  toothlike  prolongations 
Fig.  267.  which  proceed  from  its  outer  border,  is  an  extremely  slen- 

der, fibrous  band,  which  runs  along  the  side  of  the  spinal 
cord,  and  adheres  to  the  proper  sheath  of  the  cord  by  its 
inner  border,  which  is  very  thin.  The  outer  edge  is  free, 
thicker  than  the  inner  portion,  and  gives  off  certain  tooth- 
like prolongations,  which  are  attached  to  the  dura  mater  in 
the  intervals  between  the  canals  formed  by  that  membrane 
for  the  spinal  nerves :  the  first  denticulation  of  this  liga- 
ment, which  may  be  regarded  as  its  origin,  is  very  long,  and 
is  found  opposite  the  margin  of  the  foramen  magnum,  be- 
tween the  vertebral  artery  and  the  hypoglossal  nerve  ;  the 
last,  which  is  the  twentieth  or  twenty-first,  forms  the  ter- 
mination of  the  ligament,  and  corresponds  very  nearly  to 
"^3  the  lower  extremity  of  the  spinal  cord.     The  form,  thin- 

ness, and  length  of  these  toothlike  processes  are  subject  to  much  variety. 

The  ligamentum  denticulatum  is  evidently  fibrous,  and  cannot  be  regarded,  as  Bonn 
imagined,  as  a  prolongation  of  the  arachnoid.^ 

The  ligamentum  denticulatum  appears  to  answer  the  twofold  use  of  assisting  in  fixing 
the  spinal  cord,  and  of  separating  the  anterior  (a)  from  the  posterior  {b)  roots  of  the  spi- 
nal nerves. 

The  Dimensions  of  the  Spinal  Cord. 

Tlie  length  of  the  spinal  cord  in  the  adult  is  from  fifteen  to  eighteen  inches.  Its  cir- 
cumference is  twelve  lines  at  the  thinnest  part  and  eighteen  at  the  thickest.  But  it  is 
of  much  less  importance  to  determine  the  actual  dimensions  of  the  spina]  cord  than  to 
estimate  its  relative  size  as  compared  with  that  of  the  brain,  or  in  reference  to  the  ca- 
pacity of  the  vertebral  canal,  or  than  to  examine  the  differences  in  size  which  it  pre- 
sents at  different  parts  of  its  extent. 

If  the  size  of  the  spinal  cord  be  compared  with  that  of  the  whole  body,  throughout  the 
series  of  vertebrated  animals,  we  shall  perceive  that  it  always  bears  a  direct  ratio  to  the 
vital  activity  of  the  animal.  Thus  considered,  the  spined  cord  is  small  in  fishes  and  rep- 
tiles, and  large  in  birds  and  the  mammalia. 

Size  and  Weight  of  the  Spinal  Cord  compared  with  the  Size  and  Weight  of  the  Brain. — It 
was  while  studying  the  spinal  cord  and  the  brain  in  serpents  and  fishes  that  Praxagoras, 
as  quoted  by  Galen,  originated  the  idea  that  the  brain  was  a  production  of  the  spinal  cord. 
All  the  old  anatonusts,  on  the  other  hand,  who  studied  the  brain  and  cord  in  man,  in 
mammalia,  and  in  birds,  regarded  the  medulla  spinalis  as  a  prolongation  or  appendix  of 
the  brain  (tanquam  cerebri  effusionem,  Rufus) ;  indeed,  it  was  for  a  long  time  consid- 

*  The  first  description  of  the  spinal  cord  which  is  worthy  of  notice  was  given  by  Huber  (J.  Huber,  De  Me- 
duUd  Spinali,  Goeltingae,  1741) ;  it  served  as  the  basis  for  the  works  of  Haller  {Elem.  Physiol.,  torn,  iv.,  sect. 
1)  ;  of  Mayer,  who  published  a  l)eaTitiful  plate  of  it  in  1779;  and  perhaps  of  Alexander  Monro,  Secundus  (06- 
servations  on  the  Structure  and  Functions  of  the  Nervous  System,  1783).  Scsmmering-,  Reil,  and  Gall,  who 
so  successfully  studied  the  other  parts  of  the  nervous  system,  have  noticed  the  spinal  cord  in  a  superficial  man- 
ner. Chaussier  (De  V Encephale  en  general  et  en  particulier)  ;  Keuffel,  in  his  inaugural  dissertation  {De  Me- 
dulld  Spinali,  1810,  dedicated  to  Reil,  his  preceptor) ;  and  Rolando  {Richerche  Anatomiche  sulla  Strutlura  dei 
Midollo  Spinale,  Torino,  1824),  have  supplied  many  of  the  deficiencies  in  our  knowledge  of  this  part.  There 
is  a  good  description  of  the  medulla  in  M.  OUivier's  work  upon  the  diseases  to  which  it  is  subject. 

t  The  position  of  the  nervous  axis  behind  the  alimentary  canal  constitutes  one  of  the  great  differences  whicli 
exist  between  the  nervous  system  of  the  vertebrated  and  the  invertebrated  animals  ;  in  the  latter,  the  nervous 
system  lies  below,  i.  «.,  in  front  of  the  alimentary  canal. 

t  It  is  idle  to  inquire  whether  it  should  be  considered  a  prolongation  of  the  dura  mater,  or  an  eztension  at 
the  neurilemma,  or  a  proper  ligament. 


DIMENSIONS   OP   THE   SPINAL   OORD.  695 

ered  that  the  medulla  was  the  principal  nerve  in  the  body,  summus  in  corpote  humano  tier- 
vus.  In  the  present  day,  anatomists  have  returned  to  the  opinion  of  Praxagoras,  and 
the  spinal  marrow  is  generally  regarded  (Reil,  Gall,  Tiedemann)  as  the  fundamental 
part  of  the  nervous  system,  and  that  the  brain  is  merely  a  production,  an  appendage,  or 
an  expansion  of  the  cord.  I  shall  not  here  enter  into  these  purely  speculative  questions 
of  production  or  emanation,  origin,  and  relative  importance,  for  the  spinal  cord  no  more 
produces  the  brain  than  the  brain  produces  it. 

Soemmering  has  shovni  that,  in  man,  the  spinal  cord  is  smaller  in  proportion  to  the 
size  of  the  encephalon  than  in  the  lower  animals  ;  and  of  this  there  can  be  no  doubt ;  but 
it  does  not  follow  that  the  lower  animals  have  a  larger  spinal  cord  than  man  in  propor- 
tion to  the  size  of  their  bodies :  on  the  contrary,  from  actual  observation,  I  should  say 
thiit,  if  we  except  birds,  man  has  a  relatively  larger  spinal  cord  than  any  other  animal. 
Compare,  indeed,  the  medulla  of  the  horse,  or  of  the  ox,  with  that  of  man,  and  it  will  at 
once  be  found  that  the  last  is  the  largest  and  heaviest  in  proportion  to  the  rest  of  the 
body. 

According  to  Chaussier,  the  weight  of  the  spinal  cord  in  the  adult  is  from  the  nine- 
teenth to  the  twenty-fifth  part  of  that  of  the  brain,  and  in  the  newborn  infant  about  the 
fortieth  part.  According  to  Meckel,  this  last  is  also  the  proportion  in  the  adult.  It  must 
be  remembered,  however,  that  Meckel  examined  the  cord  when  deprived  of  its  proper 
membrane,  and,  therefore,  after  the  roots  of  the  nerves  were  detached  from  it. 

Size  of  the  Spinal  Cord  compared  with  the  Capacity  of  the  Spinal  Canal. — The  spinal 
cord  does  not,  by  a  great  deal,  fill  up  the  vertebral  canal,  and  a  considerable  interval  oc- 
cupied by  fluids  exists  between  it  and  the  sides  of  the  canal.  What  is  the  object  of  this 
disproportion  1  and  why  is  there  any  interval  1  We  have  already  stated  (see  Osteol- 
ogy) that  the  dimensions  of  the  canal  are  in  relation,  not  only  with  the  size  of  the  cord, 
but  also  with  the  extent  of  motion  of  the  vertebral  column.  The  opinion  of  Vieussens, 
that  this  space  is  intended  to  allow  of  certain  movements  of  elevation  and  depression  in 
the  spinal  cord  analogous  to  those  which  have  been  observed  in  the  brain,  is  sufficiently 
refuted  by  the  fact  that,  although  the  latter  organ  is  affected  by  movements  synchronous 
with  the  respiration  and  with  the  pulse,  it  still  fills  the  cavity  of  the  cranium.  * 

The  length  of  the  spinal  cord  does  not  correspond  with  that  of  the  vertebral  canal,  for 
the  cord  terminates  near  the  first  lumbar  vertebra  (between  20  and  21,  fig.  268),  while 
the  canal  is  prolonged  into  the  sacrum. 

The  position  of  the  lower  end  of  the  spinal  cord  has  not  been  determined  with  the  pre- 
cision which  so  important  a  question  demands.  According  to  Winslow,  it  terminates 
opposite  the  first  lumbar  vertebra ;  Morgagni  has  seen  it  reach  down  to  the  second  ; 
Keuffel  has  observed  it  to  descend  as  low  as  the  third  lumbar  vertebra  in  one  subject, 
and  to  terminate  opposite  the  eleventh  dorsal  vertebra  in  another.  The  discrepancy  be- 
tween various  authors  upon  this  subject  depends  upon  individual  varieties  in  the  point  of 
termination  of  the  cord,  and  upon  the  different  acceptation  of  the  term  lower  extremity 
of  the  spinal  cord  ;  some  regarding  the  thick  swollen  part  as  the  end  of  the  cord,  while 
others  include  in  it  the  tapering  portion  also.  From  some  experiments  which  I  made 
upon  this  subject  by  thrusting  a  scalpel  horizontally  from  before  backward  through  the 
inter-vertebral  substance  between  the  first  and  second  lumbar  vertebrae,  I  ascertained 
that  there  are  varieties  in  different  subjects  in  regard  to  the  point  of  termination  of  the 
spinal  cord,  and  that  it  was  influenced  by  the  position  of  the  body,  and  by  the  state  of 
flexion  or  extension  of  the  head  and  spine,  but  that,  in  general,  the  widest  part  or  base 
of  the  cone  in  which  the  cord  ends  corresponds  to  the  first  lumbar  vertebra,  and  the  apex 
of  the  cone  to  the  second. 

During  the  early  periods  of  foetal  life,  the  cord  descends  as  low  as  the  sacrum ;  but  in 
foetuses  at  the  full  time,  I  have  never  found  so  marked  a  difference  as  has  been  descri 
bed  by  some  modem  anatomists.  + 

Differences  in  the  Size  of  the  Spinal  Cord  at  different  Points  of  its  Extent.— The  spinal 
cord  is  not  of  uniform  dimensions  throughout  its  whole  extent :  it  is  much  enlarged  at 

*  From  several  experiments  which  I  have  made  upon  this  subject,  it  appeared  that  the  spinal  fluid  seen  (con- 
fined in  its  membranes)  in  the  cervical  region,  between  the  occipital  bone  and  the  axis,  was  agitated  by  move- 
ments synchronous  with  the  pulse  and  the  respiration  ;  but  that,  when  this  fluid  had  been  evacuated,  the  spi- 
nal cord  did  not  move  at  all.  I  have  examined  with  the  greatest  care  the  tumours  existing  in  the  lumbar  re- 
gion in  infants  afilicted  with  spina  bifida  ;  I  could  never  detect  in  them  any  movement  corresponding  with  the 
pulse,  but  the  movement  of  respiration  exerted  a  manifest  influence  upon  them  ;  thus,  when  the  sac  was  emp- 
tied by  compression,  the  cries  of  the  infant,  excited  by  pain,  were  almost  instantly  followed  by  extreme  ten- 
sion of  the  sac.  As  the  spinal  cord  is  not  affected  by  the  great  arteries  at  the  base  of  the  brain,  it  cannot  par- 
ticipate in  the  slightest  degree  in  those  movements  which  are  observed  in  the  spinal  fluid  at  every  puise  of  the 
heart,  and  which  are  communicated  to  that  fluid  by  the  cerebral  arteries. 

t  The  spinal  cord  is  capable  of  elongation  and  retraction  ;  it  is  elongated  during  flexion,  and  returns  to  its 
original  condition  during  extension  of  the  vertebral  column;  the  difference  between  the  two  states  appears  to 
mo  to  be  from  an  inch  to  fifteen  lines. 

In  the  body  of  an  infant  at  the  full  time,  which  was  affected  with  spina  bifida  in  the  sacral  region,  and  died 
a  short  time  after  birth,  the  spinal  marrow  descended  as  low  as  the  sacrum,  and  there  was  no  cauda  equina 
Malacarne  had  already  observed  a  similar  fact ;  this  peculiarity  depends  not  upon  an  arrest  of  development  in 
the  cord,  but  upon  adhesions  contracted  by  it  at  an  early  period  of  foetal  life. — (See  Auat.  Pathol.,  liv.  xvii., 
art  Spina  Bifida.)  vi., 


NEUROLOGY. 

its  upper  part,  opposite  the  basilar  groove,  where  it  constitutes  the  superior  or  occipital 
rachidian  bulb,  or  the  medulla  oblongata  (a) ;  it  becomes  narrowed  immediately  after  hav- 
ing emerged  from  the  foramen  magnum.  This  constriction,  which  is  named  the  neck  of 
the  rachidian  bulb,  is  regarded  by  many  anatomists  as  the  commencement  of  the  spinal  cord. 

Another  oblong  enlargement,  extending  over  a  much  greater  length  than  the  prece- 
ding, and  named  the  middle,  cervical,  or  brachial  rachidian  bulb,  or  cervical  enlargement  (6), 
commences  opposite  the  third  cervical,  and  terminates  opposite  the  third  dorsal  vertebra. 

The  spinal  cord  again  becomes  considerably  contracted  from  the  first  to  the  eleventh 
dorsal  vertebra,  and  then  presents  a  third  enlargement  of  less  extent  than  either  of  the 
other  two,  constituting  the  inferior  lumbar  or  crural  rachidian  bulb,  or  lumbar  enlargement 
(c) ;  it  then  immediately  tapers  like  a  spindle,  and  terminates  in  an  exceedingly  slender 
semi-transparent  cord,  which  has  a  fibrous,  filiform  aspect,  is  concealed  among  the 
nerves  of  the  cauda  equina  {d),  and  is  always  accompanied  by  a  vein.  This  cord  may 
be  distinguished  from  the  surrounding  nerves  by  its  being  situated  in  the  median  line, 
and  by  its  thinness,  its  fibrous  character,  and  its  termination.  It  may  be  traced  as  far 
as  the  base  of  the  sacrum,  when  it  terminates  in  the  dura  mater. 

In  some  cases  the  narrow  portion  of  the  inferior  rachidian  bulb  is  bifurcated,  but  the 
two  branches  of  the  bifurcation  terminate  in  a  single  fibrous  cord.  Huber,  Haller,  and 
Stemmering  describe  the  spinal  cord  as  terminating  below  by  two  small  globular  enlarge- 
ments, of  which  the  superior  is  oval,  and  the  inferior  conical.  They  have  evidently  mis- 
taken an  exception  for  the  rule. 

These  three  enlargements  of  the  spinal  cord  constitute  a  totally  different  structure 
from  that  admitted  by  Gall,  who,  comparing  with  Haller  the  spinal  cord  of  man,  and  the 
vertebrata  generally,  to  the  double  series  of  ganglia  in  annelida  and  insects,  maintained 
that  there  are  as  many  enlargements  of  the  cord  as  there  are  pairs  of  nerves.  A  strict 
examination  into  facts  is  completely  at  variance  with  this  opinion,  for  even  in  the  foetus, 
the  temporary  conditions  of  which  so  frequently  resemble  the  permanent  state  of  the 
lower  animals,  we  find  no  trace  of  this  series  of  enlargements.  An  erroneous  inference, 
together  with  the  aspect  of  the  cord  when  surrounded  by  its  nerves,  have  misled  this 
celebrated  physiologist,  who  should  have  sought  for  the  representatives  of  the  ganglia  of 
insects,  not  in  the  spinal  cord  itself,  but  in  the  series  of  ganglia  on  the  spinal  nerves.* 

The  existence  of  the  three  enlargements  of  the  spinal  cord  above  described  is  in  ac- 
cordance with  two  general  laws  relating  to  the  nervous  system,  viz.,  1.  That  the  size 
of  the  spinal  cord  is  in  proportion  to  the  size  and  number  of  the  nerves  which  arise  from 
and  terminate  in  it,  and  to  the  functional  activity  of  the  organs  to  which  those  nerves 
are  distributed  ;  and,  2.  That  the  exercise  of  sensibility  is  connected  with  larger  nerves 
than  that  of  muscular  contractility. 

Now  the  most  numerous  and  the  most  important  nervous  communications  take  place 
opposite  those  three  enlargements.  The  nerves  of  the  lower  extremities  correspond 
with  the  inferior  or  lumbar  enlargements  ;  those  of  the  upper  extremities,  with  the  mid- 
dle one  ;  and  the  nerves  of  respiration,  the  nerves  of  the  tongue,  and  a  part,  or  perhaps 
the  whole  of  the  nerves  of  the  face,  with  the  superior  enlargement. 

The  cervical  enlargement,  which  corresponds  to  the  upper  extremities,  is  certainly 
larger  than  the  lumbar  one,  but  this  is  because  the  upper  extremities  possess  a  greater 
degree  of  muscular  activity  than  the  lower,  and  also  because  they  are  the  organs  of  touch. 

This  explanation  is  completely  justified  by  comparative  anatomy,  and  is  applicable 
also  to  the  differences  in  the  length  of  the  spinal  cord  .-  thus,  it  is  found  that  in  the  dif- 
ferent species  of  animals,  the  length  of  the  spinal  cord  depends,  not  upon  that  of  the 
vertebral  canal,  nor  upon  the  presence  or  absence  of  a  tail,  but  is  proportionate  to  the 
muscular  energy,  and  to  the  degree  of  sensibility.  Desmoulins,  a  young  anatomist,  too 
soon  lost  to  science,  hsis  established  this  fact  by  incontrovertible  evidence.! 

The  Form,  Direction,  and  Relations  of  the  Spinal  Cord. 
The  spinal  cord  has  the  form  of  a  cylinder  flattened  in  front  and  behind  (D,  fig.  269). 

*  These  supposed  enlargements  are  not  to  be  found  even  in  the  spinal  cord  of  the  calf,  which  Gall  too*  as 
offering  the  type  of  this  structure.  The  committee  of  the  institute  likewise  failed  to  discover  them  in  the  dog, 
the  pig,  the  deer,  the  roe-buck,  the  ox,  and  the  horse,  in  which  Gall  asserted  that  he  had  found  them.  The 
beautiful  researches  of  Tiedemann  into  the  development  of  the  spinal  cord  have  completely  overthrown  Gall's 
opinion,  which  rested  merely  upon  unsubstantiated  analogies. 

[It  may  be  remarked,  that  though  Gall's  anatomical  statement  is  not  correct,  his  view  as  to  the  analogy  is 
more  in  accordance  with  received  doctrines  than  that  of  the  author.] 

t  The  spinal  cord  of  birds  furnishes  a  striking  pioof  of  the  law  which  presides  over  the  development  of  this 
part  of  the  nervous  system.  There  are  no  movements  performed  by  animals  which  require  greater  force  and 
agility  than  those  observed  in  the  act  of  flying.  It  is  therefore  not  astonishing  to  find  that  the  spinal  cord  is 
enlarged  opposite  the  nerves  which  go  to  the  muscles  of  the  wings.  It  would  be  supposed  that  the  portion  of 
the  cord  which  corresponds  to  the  lower  extremities  should  be  much  smaller  than  that  corresponding  to  the 
upper,  but  yet  the  inferior  enlargement  is  equal  to  the  one  for  the  wings,  because,  according  to  a  more  inge- 
nious than  probable  idea,  the  lower  extremities  are  the  organs  of  touch  in  birds. 

The  spinal  cord  of  the  tortoise  most  clearly  confirms  the  law  which  we  have  adopted  from  Desmoulins.  The 
sort  of  calcareous  and  homy  case  in  which  the  trunk  of  that  animal  is  enclosed  is  destitute  of  all  power  of 
motion  or  sensation  ;  and  it  is  found,  the  enlarged  part  of  the  spinal  cord  which  corresponds  to  the  upper  ex 
tremities  is  united  to  that  which  corresponds  to  the  lower  by  an  extremely  slender  portion. 


NEURILEMMA    OP    THE    SPINAL    CORD.  697 

It  exactly  corresponds  in  direction  with  the  vertebral  column,  every  deviation  of  which 
it  closely  follows  ;  and  it  is  an  interesting  fact,  that  it  escapes  compression,  even  in  an- 
gular curvatures  of  the  spine.  ' 

The  right  and  left  halves  of  the  spinal  cord  are  perfectly  symmetrical.  There  is  less 
symmetry  between  the  anterior  and  posterior  halves,  and  still  less  between  the  upper 
and  lower  halves  of  the  cord. 

The  spinal  cord  is  divided  by  anatomists  into  a  body  and  extremities.  The  body  of  the 
cord  requires  to  be  examined,  both  when  covered  by  its  proper  sheath,  and  after  the  re- 
moval of  that  membrane. 

The  Body  of  the  Spinal  Cord  enveloped  in  its  Proper  Membrane. 

The  surface  of  the  cord  everywhere  presents  certain  transverse  folds,  united  by  oth- 
ers running  obliquely,  so  as  to  form  zigzag  folds,  which  were  compared  by  Huber  to  the 
rings  of  a  silkworm,  and  regarded  by  Monro  as  so  many  small  articulations  ;  these  folds 
are  situated  in  the  sheath  of  the  cord,  and  are  precisely  analogous  to  those  which  have 
been  noticed  in  the  tendons  during  relaxation  of  the  muscles,  and  those  which  we  shall 
hereafter  have  to  describe  as  appearing  in  relaxed  nerves  ;  they  are  effaced  by  exten- 
sion of  the  spinal  cord,  and  are  reproduced  when  it  resumes  its  original  length. 

The  existence  of  these  folds  prevents  that  stretching  of  the  cord  which  would  other- 
wise occur  in  the  different  movements  of  the  vertebral  column.  They  endow  the  cord 
with  a  certain  degree  of  elasticity. 

The  spinal  marrow  presents  for  consideration  an  anterior,  posterior,  and  two  lateral 
surfaces. 

The  anterior  surface  presents  in  the  median  line  a  fibrous  band,  which  runs  along  the 
entire  length  of  the  medulla,  and  conceals  the  anterior  median  groove. 

The  posterior  surface,  at  first  sight,  presents  no  trace  of  a  median  groove.  Many 
anatomists,  therefore,  and  especially  Huber,  have  denied  its  existence  ;  but  with  a  little 
care  we  may  detect  a  very  delicate  line  which  indicates  the  situation  of  the  posterior 
median  groove,  to  which  we  shall  presently  advert.  On  each  side  of  the  median  line, 
both  on  the  anterior  and  posterior  surfaces  of  the  cord,  are  seen  the  roots  of  the  spinal 
nerves  (1  to  31,  fig.  268),  which  are  arranged  in  four  regular  lines  down  the  cord,  and  are 
divided  on  either  side  into  the  anterior  {a,  fig.  267)  and  the  posterior  {b)  roots.  The  dif- 
ferences which  we  shall  hereafter  describe  as  existing  between  these  two  sets  of  roots, 
both  in  their  number,  size,  and  mode  of  attachment,  enable  us,  at  first  sight,  to  distin- 
guish between  the  anterior  and  posterior  surfaces  of  the  cord. 

If  these  roots  be  detached,  it  will  be  seen  that  their  place  of  insertion  is  marked  by  a 
series  of  depressed  points,  which  together  constitute  two  furrows  both  upon  the  front  and 
back  of  the  cord,  accurately  described  by  Chaussier  under  the  name  of  the  collateral  fur- 
rows of  the  spinal  cord.  We  cannot  deny  the  existence  of  the  posterior  collateral  fur- 
rows, but  I  do  not  think  that  the  anterior  collateral  furrows  should  be  admitted. 

The  sides  of  the  spinal  cord  are  rounded,  and  narrower  than  either  tlie  anterior  or  the 
posterior  surface :  there  is  no  furrow  upon  these  sides,  as  described  by  some  authors. 
The  two  ligamenta  denticulata  are  attached  to  them. 

"We  must  next  examine  the  proper  membrane  of  the  cord,  or  the  rachidian  pia  mater, 
which  we  shall  name  the  neurilemma  of  the  cord,  from  its  analogy  to  the  neurilemma  of 
the  nerves ;  we  shall  then  describe  the  cord  itself 

J^eurilemma  of  the  Spinal  Cord,  or  Rachidian  Pia  Mater. 

Dissection. — It  is  difficult  to  separate  the  rachidian  pia  mater  from  the  cord,  in  the 
greater  number  of  subjects,  on  account  of  the  softness  of  the  cord  itself,  and  of  the  rapid 
changes  which  it  undergoes  after  death.  In  order  to  succeed  in  doing  so,  it  is  advisable 
to  select  the  body  of  a  person  who  has  died  from  an  acute  disease  or  from  an  accident. 
The  spinal  cord  of  new-born  infants  is  more  fitted  for  this  purpose  than  that  of  adults,  not 
only  from  its  relatively  greater  density  at  that  period  of  life,  but  also  from  its  adhesion 
to  the  neurilemma  being  less  firm. 

In  the  bodies  of  infants,  after  making  a  circular  incision  through  the  neurilemma  op- 
posite the  medulla  oblongata,  the  sheath  may  be  drawn  downward,  in  the  same  manner 
as  an  eel  is  skinned,  or  a  stocking  drawn  off  by  turning  it  inside  out.  When  the  sheath 
is  more  adherent  to  the  cord,  it  must  be  very  carefully  divided  along  each  side  of  the 
median  furrows,  and  then  detached  by  breaking  down,  with  the  handle  of  a  scalpel,  the 
cellular  and  vascular  prolongations  which  connect  it  with  the  cord. 

Although  the  proper  covering  of  the  brain,  or  cerebral  pia  mater,  consists  essentially  of 
an  interlacement  of  vessels,  the  proper  sheath  of  the  spinal  cord,  or  rachidian  pia  mater, 
is  a  fibrous,  and,  therefore,  a  strong  membrane,  which  supports  and  protects  that  part  of 
the  cerebro-spinal  axis,  as  the  neurilemma  does  the  nerves. 

The  external  surface  of  this  membrane  is  surrounded  with  a  network  of  remarkably 
tortuous  bloodvessels  ;  and  vessels  are  also  found  in  its  substance.  The  spinal  cord  is 
visible  through  this  semi-transparent  membrane,  which  is  naturally  of  a  pearly-white 

4T 


698  NEUROLOGY. 

colour,  but  IS  sometimes  dull,  yellowish,  blackish,  or  even  covered  with  black  spots,  es- 
pecially in  the  cervical  region.* 

This  surface  of  the  rachidian  neurilemma  is  also  rough,  being  covered  with  small  cel- 
lular and  fibrous  filaments  which  float  under  water,  and  are  the  remains  of  small  fibrous 
cords,  which  extended  from  the  neurilemma  to  the  arachnoid. 

The  internal  surface  of  the  neurilemma  adheres  to  the  spinal  cord  by  a  great  number 
of  cellular  and  vascular  prolongations,  which  form  areolae  or  meshes  in  its  interior,  and 
which  have  been  well  described  and  figured  by  Keuffel. 

Along  the  anterior  median  furrow,  the  neurilemma  sends  off  a  prolongation,  which,  en- 
tering that  furrow,  lines  one  of  its  walls,  and  is  then  reflected  at  its  bottom,  so  as  to  hne 
the  other  waU ;  within  the  substance  of  the  duplicature  thus  formed,  the  bloodvessels 
penetrate.  A  simple  prolongation  of  the  neurilemma,  of  extreme  tensity,  also  enters 
into  the  posterior  median  furrows,  and  forms  a  line  of  separation  between  the  two  pos- 
terior halves  of  the  spinal  cord. 

The  neurilemma  is  prolonged  below  the  lower  extremity  of  the  spinal  cord  as  a  fibrous 
filament,  very  well  described  by  Huber,  which  is  inserted  into  the  base  of  the  coccyx. 

This  filament  the  older  anatomists  regarded  as  a  nerve,  and  named  it  the  nervus  impar ; 
it  is  very  strong  considering  its  thinness  ;  it  is  always  tense,  and  appears  to  be  intended 
to  fix  the  lower  end  of  the  spinal  cord ;  in  this  respect  serving  a  similar  purpose  with  the 
ligamentum  denticulatum.  Its  upper  part  is  hollow,  and  is  filled  with  a  gray  and  ex- 
tremely soft  substance. 

The  ligamentum  denticulatum,  which  has  been  considered  as  a  prolongation  of  the  prop- 
er membrane  of  the  cord,  is  attached  to  the  external  surface  of  this  membrane  ;  and  the 
proper  neurilemma  of  each  nervous  filament  is  also  given  off  from  this  surface. 

Monro  has  stated  that  a  soft  layer  of  gray  substance  covers  the  white  substance  of  the 
spinal  cord,  and  separates  it  from  its  neurilemma,  but  such  a  layer  does  not  exist. t 

While  the  other  membranes  of  the  spinal  cord  are  much  larger  than  the  part  which 
they  have  to  invest,  the  neurilemma  of  the  cord  is  exactly  moulded  upon  it,  and  even 
exerts  a  certain  degree  of  pressure  upon  it,  as  is  evident  from  the  manner  in  which  the 
substance  of  the  cord  protrudes  when  this  covering  is  punctured ;  this  compression  oc- 
casions the  apparent  consistence  of  the  cord  when  it  is  enveloped  in  its  sheath  ;  a  con- 
dition which  contrasts  so  strongly  with  its  softness  when  that  sheath  has  been  removed. 

This  compression,  as  well  as  the  absolute  inextensibility  of  the  neurilemma,  accounts 
for  the  rarity  of  effusions  in  the  cord,  and  also  for  the  fatal  effects  of  even  the  slightest 
effusions  within  its  substance  when  they  do  occur. 

Structure. — The  proper  membrane  of  the  cord  is  essentially  fibrous ;  nor  has  it  any 
claim  to  be  termed  a  vascular  membrane  (tunica  vasculosa,  Soemmering).  Its  component 
fibres  interlace  in  every  direction,  but  the  majority  of  them  are  longitudinal.  It  is  quite 
evident  that  the  vessels  which  ramify  upon  its  surface,  and  afterward  penetrate  it,  do 
not  belong  to  the  membrane  itself. 

Uses. — The  neurilemma  is  essentially  a  protecting  structure  ;  it  constitutes  the  frame- 
work of  the  spinal  cord,  and  serves,  at  the  same  time,  as  a  support  for  the  nutritious  ves- 
sels of  that  organ ;  in  this  latter  respect  it  has  been  compared  to  the  pi  a  mater  of  the 
brain.  The  transition  from  the  spinal  into  the  cerebral  portion  of  the  pia  mater  takes 
place  gradually.  The  fibrous  character  of  this  tunic  diminishes  upon  the  medulla  oblon- 
gata and  tuber  annulare,  and  is  entirely  lost  opposite  the  peduncles  of  the  brain ;  while 
its  vascular  character,  on  the  contrary,  becomes  gradually  more  and  more  marked  as  it 
passes  from  the  cord  towards  the  brain. 

It  has  been  stated  that  the  neurilemma  is  the  secreting  organ  of  the  spinal  cord ;  one 
might  as  well  say  that  the  testicle  is  secreted  by  the  tunica  albuginea,  and  the  heart  by 
the  pericardium. 

The  Body  of  the  Spinal  Cord  deprived  of  its  J^eurilemma. 

When  the  neurilemma  of  the  cord  is  removed,  the  spinal  nerves  are  also  taken  away. 
We  shall  hereafter  have  to  inquire  whether  this  fact  should  lead  us  to  conclude  that 
the  nerves  do  not  enter  into  the  substance  of  the  cord,  but  merely  come  into  contact 
with  it. 

We  would  observe,  however,  in  this  place,  that  the  posterior  roots  of  the  spinal  nerves 
arise  in  a  perfectly  regular  line,  while  the  anterior  roots  come  off  irregularly  from  differ- 
ent points  of  the  corresponding  medullary  column,  t 

The  Anterior  Median  Grocwe  and  the  Commissure. — The  anterior  median  groove,  or  fissure 

*  These  different  shades  of  colour  are  much  more  common  in  certain  animals,  in  the  sheep,  for  example, 
than  in  man  ;  they  result  from  the  deposition  of  a  colouring  matter,  and  are  in  no  way  connected  with  any 
recent  or  previous  morbid  action. 

t  In  several  subjects,  I  have  most  distinctly  seen  a  very  thin  yellowish  layer  over  the  medulla  oblongata, 
which  dipped  between  the  pyramidal  bodies,  and  filled  up  the  shallow  groove  which  separates  the  olivary  from 
the  pvramidal  bodies. 

X  This  mode  of  origin  of  the  anterior  roots  is  perfectly  distinct  in  the  spinal  cord  of  the  futus  or  new-bom 
infant ;  up  to  this  period,  the  tract  from  which  the  anterior  roots  arise  is  still  formed  of  gray  substance.  Th« 
roots,  which  are  white,  emerge  fmm  this  gray  tract,  and  when  the  neurilemma  is  removed,  their  small,  white, 
ruptured  ends  which  remain  may  be  traced  into  the  substance  of  the  cord. 


THE    SPINAL  CORD   DEPRIVED   OF   ITS   NEURILEMMA. 


Fig.  268. 


(Jig.  26R ;  f,  fig.  269,  D),  penetrates  to  about  one 
third  of  the  thickness  of  the  cord.  At  the  bottom 
of  the  groove,  which  is  occupied  by  a  prolongation 
of  the  neurilenuna  and  a  great  number  of  vessels, 
is  seen  an  extremely  thin  white  layer,  perforated 
with  foramina,  which  is  named  the  anterior  com- 
missure (commissure  longitudinale,  Chaussier).  The 
foramina  in  this  structure  are  intended  for  the  trans- 
mission of  tufts  of  vessels,  which  enter  the  sub- 
stance of  the  cord.  The  alternate  arrangement  of 
these  foramina  greatly  increases  the  difficulty  of 
drawing  out  the  vessels,  and  gives  to  the  commis- 
sure the  appearance  of  being  formed  by  interlacing 
fibres ;  and,  in  fact,  several  anatomists  have  not 
only  admitted  such  an  interlacement,  but  have  ex- 
pressly stated  that  it  was  produced  by  the  spinal 
nerves  themselves.* 

According  to  Gall  and  Spurzheim,  the  bundles  of 
which  this  commissure  consists  are  directed  trans- 
versely, and  are  fitted  into  each  other  like  the  mo- 
lar teeth ;  but  I  repeat,  that  the  most  careful  ex- 
amination demonstrates  nothing  in  the  commissure, 
besides  a  white  lamella,  perforated  for  the  transmis- 
sion of  bloodvessels. 

The  Posterior  Median  Groove. — The  posterior  me- 
dian groove  or  fissure  (a)  not  only  exists,  but  is 
much  deeper  than  the  anterior  one.  Its  narrow- 
ness, and  the  tenuity  of  the  membranous  prolon- 
gation which  enters  it,  have  alone  concealed  it  from 
the  observation  of  anatomists ;  there  is  no  white 
band  analogous  to  that  of  the  anterior  median  fis- 
sure at  the  bottom  of  this  fissure,  but  the  gray  sub- 
stance of  the  commissure  is  all  that  is  seen. 

As  there  are  two  median  furrows,  it  follows  that 
there  are  really  two  distinct  spinal  cords,  connected 
together  by  an  extremely  thin  band  or  commissure. 

The  Furrows  opposite  the  Posterior  Roots  of  the 
Nerves,  or  the  Posterior  Lateral  Furrows. — Immedi- 
ately to  the  outer  side  of  the  line  of  origin  of  the 
posterior  roots  of  the  spinal  nerves,  there  is  a  gray- 
ish line  or  furrow  (i),  which  extends  the  whole 
length  of  the  cord.  If  a  stream  of  water  be  allowed 
to  fall  upon  this  line,  the  continuity  of  the  cord  is 
soon  destroyed,  and  the  water  penetrates  to  the 
centre  of  the  organ. 

But  there  are  no  true  fissures  in  these  situations 
analogous  to  the  anterior  and  posterior  median  fur- 
rows. The  separation  is  effected  by  the  destruc- 
tion of  the  gray  substance,  a  prolongation  of  which 
reaches  to  the  surface  of  the  cord  opposite  these 
points.  We  shall,  nevertheless,  suppose  these  fur- 
rows to  exist  in  accordance  with  the  views  of  Soem- 
mering and  Rolando,  who  divided  each  half  of  the 
spinal  cord  into  two  columns :  a  posterior  column, 
consisting  of  that  portion  (e)  which  is  comprised  be- 
tween the  posterior  median  furrow  (a)  and  the  posterior  roots  (i) ;  and  an  antcro-lateral 
column,  including  all  that  portion  (rf)  which  is  situated  between  the  anterior  median  fur- 
row (/)  and  the  supposed  posterior  lateral  furrow  (r).  We  must  also  admit,  with  Haller, 
Chaussier,  Gall,  and  Rolando,  a  third  column  on  each  side  ;  these  may  be  called  the  pos- 
terior median  columns,  and  are  continuous  with  the  projecting  bundles  which  form  the 
borders  of  the  calamus  scriptorius,  and  which  are  each  limited  externally  by  a  slight 
groove.  These  small  and  exceedingly  narrow  columns,  the  existence  of  which  is  admit- 
ted by  most  anatomists  in  the  cervical  region  only,  are  prolonged  through  the  whole  ex- 
tent of  the  spinal  cord. 

Is  there  an  anterior  lateral  furrow  ?  If  the  line  on  the  outer  side  of  the  attachment  of 
the  anterior  roots  of  the  spinal  nerves  be  closely  examined,  the  appearance  of  a  furrow 
is  seen  along  the  whole  of  the  cord.     But  if  water  be  allowed  to  fall  upon  that  line,  it  is 


*  There  is  uo  physiological  or  pathological  fact  which  demonstrates  the  crossing 
nal  cord. 


eiTect  of  lesions  of  the  spi 


700  NEUROLOGY. 

found  that  there  is  no  fissure  or  furrow  properly  so  called,  and  that  the  jet  of  water  has 
no  more  effect  upon  this  line  than  on  the  adjoining  parts  ;  we  are  therefore  led  to  reject, 
with  Rolando,  both  these  anterior  lateral  furrows  and  the  lateral  tracts  described  by 
Chaussier,  which  would  be  bounded  in  front  by  the  furrow  of  the  anterior  roots,  and  be- 
hind by  that  of  the  posterior  roots  ;  these  lateral  tracts  have,  nevertheless,  become  cele- 
brated, since  so  much  importance  has  been  attached  to  them  by  Sir  C.  Bell  and  Bellin- 
geri  as  the  lateral  columns  of  the  spinal  cord. 

From  what  has  been  stated  above,  it  follows  that  each  half  of  the  cord  is  composed 
of  two  columns,  a  posterior  and  an  antero-lateral,  and  as  an  appendage  to  the  posterior 
column,  of  a  small  column,  which  forms  the  border  of  the  posterior  median  furrows. 

Internal  Structure  of  the  Spinal  Cord. 
The  following  results  regarding  the  structure  of  the  cord  have  been  obtained  by  va- 
rious modes  of  investigation  :  by  making  sections  of  it ;  by  acting  upon  it  with  a  stream 
of  water ;  by  hardening  it  in  alcohol  and  dissecting  it ;  by  studying  its  development ; 
and,  lastly,  by  a  reference  to  its  comparative  anatomy,  which  appears  to  be  necessary  to 
complete  the  knowledge  acquired  by  the  other  means  of  investigation. 

Sections  of  the  Cord. 
'  It  appears,  from  an  examination  of  the  external  structure  of  the  spinal  cord,  that  it 
consists  of  two  white,  juxtaposed  cylinders  ;  that  the  surfaces  by  which  these  cylinders 
correspond  are  flat,  closely  in  contact,  and  united  together  by  a  median  commissure ; 
and  that  each  of  them  may  be  divided  into  two  columns,  the  one  posterior  and  smaller, 
of  which  the  posterior  median  column  is  only  an  appendage;  the  other,  antero-lateral, 
which  forms  two  thirds  of  the  circumference  of  the  cylinder. 

Horizontal  Sections. — If  various  horizontal  sections  be  made  through  different  parts  of 
Fig.  269.  t^^  spinal  cord,  we  see  that  each  half  consists  of  a  cylinder  of  white 
substance,  containing  gray  substance  in  its  interior  (see  Jig.  269,  D) ; 
that  the  median  commissure  is  composed  of  a  white  layer  {white  commis- 
sure) and  a  gray  layer  (gray  commissure) ;  and  that  in  each  section  the 
gray  matter  has  a  tolerably  close  resemblance  in  form  to  the  letter  x,  the 
two  halves  or  curves  of  which  are  joined  in  the  middle  by  a  horizontal 
line,  while  the  extremities  of  the  curves  are  directed  towards  the  ori- 
gins of  the  anterior  and  posterior  roots  of  the  nerves.  The  posterior 
I B  extremities  reach  much  nearer  to  the  surface  than  the  anterior.  We 
perceive,  also,  in  these  different  sections,  that  the  circumference  of  the 
cord  is  not  perfectly  regular,  but  is  somewhat  sinuous,  as  we  shall  pres- 
ently mention. 

The  size  of  the  central  gray  mass  in  each  half  of  the  spinal  cord,  the 
length  and  thickness  of  the  prolongations  or  points,  which  it  sends  off 
towards  the  anterior  and  posterior  roots,  and,  lastly,  the  thickness  of 
the  gray  commissure,  present  many  varieties,  according  to  the  place  of 
section  ;*  and  hence  there  is  a  discrepancy  between  different  authors 
as  to  the  appearances  of  this  section.  Thus,  Huber  compared  the  sec- 
tion of  the  gray  matter  to  an  os  hyoides  ;  Monro,  to  a  cross  ;  Keuffel,  to 
four  rays  converging  towards  a  central  point. 
Rolando  has  given  figures  of  sections  of  the  cord  at  every  part  of  its  length. 
From  sections  of  the  cord  the  general  fact  is  established,  that  the  white  substance  en- 
closes the  gray  matter.  The  thin  layer  of  gray  matter  on  the  surface  of  the  cord  ad- 
mitted by  Monro  has  been  justly  rejected  by  all  anatomists.  The  relative  situation  of 
the  two  substances  in  the  cord,  which  is  the  reverse  of  what  is  observed  in  the  brain, 
has  attracted  the  attention  of  anatomists,  and  various  explanations,  of  greater  or  less 
ingenuity,  but  all  hypothetical,  have  been  given  of  this  fact. 

According  to  Rolando,  there  are  two  kinds  of  gray  matter  in  the  cord,  one  occupying 
the  anterior,  and  the  other  the  posterior  half  of  the  cylinder  ;  and  these  two  halves  are 
fitted  into  each  other  by  a  series  of  indentations,  like  the  bones  of  the  cranium. 

I  have  never  been  able  to  convince  myself  of  the  existence  of  these  two  kinds  of  gray 
matter,  but  I  have  distinctly  observed  the  denticulated  appearance  of  the  circumference 
of  the  gray  matter,  which  indicates  that  the  gray  and  white  matter  mutually  penetrate 
into  each  other. 

The  colour  of  the  gray  substance  varies  considerably.  In  some  subjects  it  is  whitish, 
and  can  only  be  distinguished  from  the  white  matter  by  its  softness,  its  vascularity,  and 
its  not  having  a  fibrous  structure.  The  younger  the  individual,  the  more  marked  is  the 
difference  in  colour  between  the  two  substances. 

The  two  substances  appear  also  to  differ  in  their  relative  proportions  in  different  in- 
dividuals.    Keuffel  has  ascertained  that  the  gray  matter  is  more  abundant  in  man  than 

*  I  would  recommend  five  sections  of  the  cord,  which  appear  to  rae  to  give  a  very  accurate  notion  of  its  in- 
ternal structure  :  the  first  should  be  immediately  below  the  decussation  of  the  pyramids ;  the  second  through 
the  middle  of  the  brachial  enlargement ;  the  third  through  the  dorsal  constricted  part ;  the  fourth  through  the 
middle  of  the  lumbar  enlargement ;  and  the  fifth  near  the  apex  of  the  cone  formed  by  the  lumbar  enlargement. 


INTERNAL  STRUCTURE  OP  THE  SPINAL  CORD.         ^'Wl 

in  the  lower  animals  ;  and  this  fact  would  account  for  the  pre-eminent  sensibility  of  the 
human  subject,  in  accordance  with  the  view  of  BeUingeri,  who  considers  that  the  gray 
matter  is  the  seat  of  sensation. 

These  horizontal  sections  enable  us  not  only  to  determine  the  relative  position  and 
proportions  of  the  white  and  gray  substances,  but  also  to  distinguish  the  superficial  fur- 
rows from  those  which  really  enter  into  the  cord  ;  the  existence  of  these  columns  in  the 
spinal  cord,  which  have  already  been  described,  is  in  this  way  fully  established. 

Vertical  Sections. — The  most  important  of  these  is  one  made  from  before  backward  in 
the  median  line,  so  as  to  separate  the  two  halves  of  the  cord.  Each  of  these  halves  may 
then  be  unfolded  like  a  riband,  on  the  inner  surface  of  which  the  gray  matter  forms  a 
thin  layer. 

A  transverse  vertical  section,  through  the  centre  of  the  cord,  displays  the  mode  of 
origin  of  the  anterior  and  posterior  roots  of  the  nerves. 

Examination  of  the  Spinal  Cord  under  a  Stream  of  Water. 

The  different  sections  above  mentioned  expose  the  general  internal  arrangements  of 
the  cord  rather  than  its  actual  structure. 

Until  lately,  authors  had  regarded  the  spinal  cord  as  consisting  of  a  semi-fluid  pulp, 
which  oozed  out  when  the  neurilemma  was  divided.  Several  had  said,  incidentally,  and 
without  distinguishing  between  the  white  and  the  gray  substance,  that  the  cord  had  a 
fibrous  structure,  and  that  its  fibres  were  directed  longitudinally.  Gall  supposed  the 
cord  to  consist  of  a  series  of  ganglia,  arranged  one  upon  the  other  ;  but  it  is  now  gener- 
ally admitted  that  the  white  matter  is  fibrous,  and  that  its  fibres  have  a  linear  arrange- 
ment ;  and  this  is  clearly  shown  by  examining  this  organ  by  means  of  a  stream  of  water, 
the  force  and  size  of  which  may  be  varied  at  will. 

When  directed  upon  the  surface  of  a  vertical  section,  made  from  before  backward 
down  the  middle  line,  the  stream  of  water  penetrates  the  substance  of  the  cord  through 
the  gray  commissure,  breaks  down  the  central  gray  matter,  and  spreads  the  cord  out 
like  a  riband,  from  which  it  is  very  difficult  to  wash  off  all  the  gray  matter.  When 
treated  in  this  way,  each  half  of  the  cord  is  almost  immediately  subdivided  into  two  col- 
umns, and  if  the  stream  of  water  be  now  directed  upon  the  internal  surface  of  the  col- 
umns themselves,  they  may  be  separated  into  a  great  number  of  wedge-shaped  vertical 
lamellae,  directed  from  the  circumference  to  the  centre,  the  thick  external  backs  of  which 
are  turned  towards  the  surface,  and  the  thin  internal  edges  towards  the  centre  of  the 
cord.  Now,  as  all  these  lamellae  are  not  of  equal  depth  from  back  to  edge,  their  internal 
edges  reach  to  different  distances  from  the  centre  ;  hence  the  denticulated  appearance 
of  the  circumference  of  the  gray  matter  in  a  section ;  and  hence,  also,  the  mistake  of 
Rolando,  in  describing  the  white  matter  as  formed  by  a  medullary  layer,  folded  a  very 
great  many  times  upon  itself* 

According  to  my  observations,  each  lamella  is  completely  independent  of  the  adjacent 
ones  ;  and  pathological  anatomy  fully  confirms  this  observation,  by  showing  that  one  only 
may  be  altered  or  atrophied,  while  the  others  remain  unaffected. 

If  the  action  of  the  stream  of  water  be  continued,  these  medullary  lamellae  are  decom- 
posed into  very  delicate  juxtaposed  filaments,  which  extend  along  the  entire  length  of 
the  cord  ;  they  are  all  independent  of  each  other,  and  are  merely  connected  by  cellular 
tissue  and  some  vessels. 

The  structure  of  the  spinal  cord  is  therefore  filamentous  or  fasciculated ;  its  filaments 
are  almost  perfectly  identical  with  those  which  constitute  the  proper  substance  of  the 
nerves.  Each  filament  in  the  cord  traverses  its  entire  length,  as  each  nervous  filiiment 
extends  along  the  whole  nerve. 

The  very  important  inference  to  be  drawn  from  these  facts  is  the  independence,  not 
only  of  each  lamella,  but,  I  may  venture  to  say,  of  each  filament,  t 

*  Rolando  has  even  counted  these  folds :  he  numbers  fifty  in  the  spinal  cord  of  the  ox,  opposite  the  origin 
of  the  sixth  pair  of  sacral  nerves,  and  about  thirty  opposite  the  third  pair  of  sacral  nerves  ;  both  of  these  ob- 
servations refer  to  the  anterior  columns  only,  for  in  the  two  figures  which  he  gives  of  them  the  posterior  col- 
umns appear  to  have  no  folds.  Rolando  made  his  observations  upon  spinal  cords  which  had  been  macerated 
eil'jcr  in  pure  water  or  in  salt  and  water. 

t  [The  microscopic  structure  of  the  white  and  gray  substances  of  the  brain  and  spinal  cord  has  been  inves- 
tigated by  Fontana,  Ehrenberg,  Weber,  Remak,  Valentin,  and  others.  The  fibres  of  the  white  matter  consist 
of  coherent  threads  of  a  soft,  semi-transparent,  tenacious  substance,  enclosed  in  an  extremely  delicate  homo- 
geneous or  structureless  sheath,  which  is  very  difficult  of  detection :  these  fibres  are  smaller  than  those  of  the 
nerves  ;  they  differ  much  in  size,  but  each  of  them  is  of  uniform  diameter  throughout  ;  when  submitted  to 
the  slightest  pressure  during  examination,  they  have  a  remarkable  tendency  to  become  varicose  or  beaded,  a 
property  which  is  peculiar  to  them  and  to  the  fibres  of  the  olfactory,  optic,  and  auditory  nerves,  which  also  re- 
semble the  fibres  of  the  brain  in  other  respects. 

The  gray  matter  of  the  brain  and  spinal  cord  consists  of  large  reddish  gray  globules,  containing  a  nucleus 
and  one  or  more  nucleoli,  and  having  spots  of  pigment  upon  them,  in  situations  where  the  gray  matter  is  dark- 
er than  usual.  Surrounding  and  attached  to  these  globules  there  are  minute  jointed  fibres,  which  are  marked 
at  intervals  with  granules  (nuclei)  ;  by  Ehrenberg  these  jointed  fibres  were  considered  to  be  of  the  same  na- 
ture as  the  fibres  of  the  white  matter,  differing  from  them  only  in  size  ;  by  Miiller  and  Schwann  they  are  re- 
garded as  organic  nervous  fibres,  resembling  those  found  in  such  abundance  in  the  sympathetic  nerves  and 
ganglia ;  while  by  Valentin  and  others  they  are  supposed,  not  only  in  the  brain,  but  also  in  the  ganglia  and 
nerves,  to  be  the  filaments  of  a  delicate  cellular  tissue. 

The  mode  in  which  the  white  fibres  of  the  brain  and  spinal  cord  end  in  the  gray  substance  is  not  well  made 


I9|tt  NEUROLOGY. 

Examination  of  the  Spinal  Cord  hardened  in  Alcohol. 
When  deprived  of  its  humidity  by  alcohol,  the  spinal  marrow  becomes  very  firm,  ex- 
tensible, and  elastic.  Its  filamentous  texture  becomes  very  apparent,  and  the  filaments 
themselves,  which,  from  the  contraction  of  the  cord,  are  flexuous,  may  be  separated 
from  each  other,  either  by  the  handle  of  the  scalpel,  or  by  slight  traction.  I  have  not 
seen  that  interlacement  of  the  fibres  of  the  cord  which  is  figured  in  the  beautiful  plates 
of  Herbert  Mayo,  and  which,  in  my  opinion,  is  only  apparent,  and  is  produced  by  drawing 
the  parts  under  examination  in  different  directions. 

The  Cavities  or  Ventricles  of  the  Spinal  Cord. 

Several  anatomists  are  of  opinion  that  there  is  a  canal  in  each  half  of  the  spinal  cord.* 

Morgagni  has  slightly  alluded  to  its  existence,  which  he  had  not  leisure  to  trace  for  a 
greater  extent  than  about  five  fingers'  breadth,  t 

Gall  relates  that,  in  examining  the  body  of  an  infant  8iffected  with  spina  bifida,  he  cut 
transversely  through  the  cord,  and  found  that  it  contained  two  canals,  which  he  traced 
into  the  substance  of  the  medulla  oblongata  and  tuber  annulare,  beneath  the  tubercula 
quadrigemina,  and  as  far  as  the  optic  thalami,  where  they  terminated  in  a  pouch  as  large 
as  an  almond.t 

It  is  certain  that,  up  to  the  fourth  month  of  foetal  life,  each  half  of  the  spinal  cord  con- 
tains a  canal  precisely  similar  to  that  which  exists  in  fishes ;  but  after  this  time  the  gray 
matter  takes  the  place  of  the  gelatiniform  fluid  which  had  occupied  the  canal.  However, 
in  one  case  I  found  the  canal  persisting  after  birth. 

The  Medulla  Oblongata. 
Situation. — The  medulla  oblongata,  the  rachidian  bulb,  or  cranial  enlargement,  is  that 
conoid  enlargement  (a,  fig.  268)  which  forms  the  upper  part  of  the  spinal  cord,  crowning 
it  like  the  capitsil  of  a  column :  it  is  situated  upon  the  basilar  groove  of  the  occipital 
bone,  and  connects  the  spinal  cord  with  the  cerebrum  and  cerebellum.  It  was  named 
medulla  oblongata  by  Haller  ;  but  it  has  also  been  called  the  cauda  or  tail  of  the  medulla 
oblongata,  this  term  being  derived  from  a  comparison  of  the  pons  Varolii,  the  four  pe- 
duncles, and  the  medulla  oblongata  to  an  animal,  the  body  of  which  was  represented  by 
the  tuber,  the  arms  by  the  anterior  peduncles,  the  legs  by  the  posterior  peduncles,  and 
the  tail  by  the  rachidian  bulb. 

External  Conformation  of  the  Medulla  Oblongata. 

The  medulla  oblongata  is  received  into  the  deep  groove  on  the  fore  part  of  the  cir- 
cumference of  the  cerebellum  (see  fig.  276),  so  that  its  anterior  part  only  is  exposed. 

In  man  and  the  mammalia  the  medulla  oblongata  is  bounded  above  and  in  front  by  the 
tuber  annulare  or  pons  Varolii  {a,  fig.  270) ;  but  above  and  behind  its  limits  are  quite  arti- 
ficial, for  it  is  prolonged  upward  beyond  the  pons,  cis  we  shall  presently  see.  Its  limits 
below  are  altogether  arbitrary :  the  medulla  oblongata,  in  fact,  does  not  contract  abrupt- 
ly, as  the  term  neck  of  the  bulb,  applied  to  its  lower  extremity,  would  seem  to  imply,  but 
it  is  very  gradually  narrowed,  so  as  to  become  continuous  with  the  spinal  cord. 

A  plane,  which  is  a  tangent  of  the  lower  surface  of  the  condyles  of  the  occipital  bone, 
would  correspond  with  the  lower  boundary  of  the  medulla  oblongata.  ^  I  think,  however, 
that  it  is  more  rational  to  fix  this  boundary  according  to  the  precise  point  where  the  me 
dulla  undergoes  some  decided  modifications ;  and  this  point  is  immediately  below  the 
decussation  of  the  pyramids. 

The  medulla  oblongata  is  from  fourteen  to  fifteen  lines  in  length,  nine  lines  in 

out ;  according  to  Valentin,  they  separate  to  admit  the  gray  globules  between  them,  and  then  unite  with  one 
another  so  as  to  form  loops. 

The  substance  of  the  brain  and  spinal  cord,  according  to  Vauquelin,  contains  80  per  cent,  of  water  ;  its  solid 
constituents  consist  of  albumen,  stearine  and  elaine,  phosphorus  (1-5  per  cent.),  osmazome,  some  acids  and 
salts,  and  sulphur.] 

*  It  is  unnecessary  to  say,  that  the  existence  of  the  single  central  canal  admitted  by  some  authors,  is  quite 
irreconcilable  with  the  real  structure  of  the  cord. 

t  Adversaria  Anat. ,\ol.  i.,  p.  17.  Morgagni  relates  that,  having  separated  the  medulla  oblongata  from  the 
rest  of  the  spinal  cord  by  a  horizontal  section,  he  saw  in  the  substance  of  the  cord,  and  for  the  space  of  about 
five  fingers'  breadth  (etfortasse  etiam  hngius  siquis  tunc  otium  habuisset  ulteriorum  meduUam  e  vertebris  exi- 
mendi),  a  cavity  which  admitted  the  end  of  the  finger ;  everything  appeared  to  be  in  a  natural  state,  except- 
ing this  cavity.  He  adds,  that  he  had  never  met  with  so  large  a  cavity ;  which  seems  to  imply  that  he  had 
seen  cavities  of  this  kind  before. — Negue  enim  alias  tantam  out  qua:  huic  accederet  vidi. 

t  Spina  bifida  and  hydrocephalus  have  no  direct  relation  with  the  persistence  of  the  canals  of  the  spinal 
cord  ;  and  on  this  point,  I  can  remove  all  the  doubts  expressed  by  Keuffel  (De  Medulld  Spinali,  62)  concerning 
Morgagni's  observation.  "  Forsan  nos  quoque,"  says  Keuffel,  "earn  (scilicet  medulla;  spinalis  caveam)  inve- 
nissemus,  si  medullam  spinalem  ex  homine  hydrocephalico  aut  spinJl  l)ifid^  laborante,  inquirere  potuissemus. 
Utinam  hujusmodi  opportunitas,  si  occurreret,  a  nemine  negligatur,  ut  tandem  de  hJlc  re  certiores  fiamus." 
In  five  infants  affected  with  spina  bifida,  and  two  who  died  of  chronic  hydrocephalus,  which  I  examined  for 
this  purpose,  the  spinal  marrow  was  perfectly  normal.  Tiedemann  regards  the  canals  described  by  Gall  as 
produced  by  insufflation. 

t)  I  have  made  experiments  upon  several  subjects,  which  show  that  the  relations  of  the  medulla  oblongata 
to  the  foramen  magnum  vary  according  as  the  head  is  directly  vertical,  flexed,  or  extended  ;  an  instrument 
thrust  horizontally  between  the  atlas  and  occipital  bone  divides  the  medulla  oblongata  at  different  part*  n 
these  various  positions  of  the  head. 


THE  MEDULLA  OBLONGATA,  ETC.  708 

breadth,  and  six  in  thickness  ;  it  is  therefore  much  broader  and  thicker  than  the  spinal 
cord. 

The  medulla  oblongata  is  directed  obliquely,  like  the  inclined  plane  of  the  basilar 
groove,  so  that  it  forms  with  the  spinal  cord  a  very  obtuse  angle,  which  projects  back- 
ward. 

In  shape  it  resembles  a  cone  flattened  in  front  and  behind,  and  having  its  base  turned 
upward  and  its  apex  downward ;  it  has,  therefore,  four  surfaces,  viz.,  an  anterior,  a  pos- 
terior, and  two  lateral. 

Anterior  Surface  of  the  Medulla  Oblongata. 

This  surface  (fig.  270)  is  directed  downward,  and  is  therefore  named  inferior  by  some 
anatomists ;  it  is  convex,  and  is  lodged  in  the  basilar  groove  of 
the  occipital  bone ;  it  can  be  properly  examined  only  after  its  '^'    _' 

neurilemma  has  been  dissected  off,  which  is  easily  done,  because 
its  substance  is  denser  than  the  spinal  cord. 

On  this  surface  we  observe  a  median  furrow  (/),  into  which 
numerous  vessels  enter  :  this  furrow,  which  is  not  nearly  so  deep 
as  the  anterior  median  furrow  of  the  spinal  cord,  with  which  it  is 
continuous,  is  interrupted  by  a  decussation  of  fibres  about  ten  si^ 
lines  below  the  pons  Varolii  (below  n),  and  terminates  above  in 
a  tolerably  deep  fossa  (le  trou  borgne,  or  foramen  cacum,  of  Vicq 
d'Azyr),  at  the  point  where  the  furrow  meets  the  pons.  Not  un- 
frequently  some  transverse  fibres  occupy  the  place  of  this  median 
furrow,  in  which  case  the  anterior  surface  of  the  medulla  ob- 
longata resembles  the  pons  Varolii ;  sometimes  these  transverse  fibres  are  found  upon 
only  a  part  of  the  medulla  oblongata. 

On  each  side  of  this  median  furrow  are  seen  two  eminences,  which  seem  as  if  mould 
ed  in  relief  upon  the  part,  and  which  form  two  planes,  succeeding  one  another  like  steps 
from  within  outward.     The  two  internal  eminences  are  called  the  anterior  pyramids ;  the 
two  external  are  named,  from  their  shape,  the  olivary  bodies. 

The  interior  Pyramids. 

The  anterior  pyramids  ( Vieussens,  b  b),  situated  on  each  side  of  the  median  line,  and 
to  the  inner  side  of  the  olivary  bodies,  are  two  white  pyramidal  bundles  (bandes  medul- 
laires,  Maiacarne),  which  extend  through  the  entire  length  of  the  medulla  oblongata ; 
they  project  in  relief  upon  the  body  of  the  medulla,  and  seem  to  emerge  or  originate 
near  its  narrow  portion  or  neck,  where  they  separate  from  each  other  the  anterior  col- 
umns of  the  spinal  cord,  from  which  columns  they  are  quite  distinct :  at  their  point  of 
emergence  they  are  closely  approximated  and  narrow,  being  about  a  line  and  a  half  in 
width ;  they  pass  somewhat  obliquely  upward  and  outward,  become  more  prominent, 
and  about  three  lines  wide  ;  having  reached  the  pons  Varolii,  they  become  rounded  and 
cylindrical,  and  are  constricted  before  they  enter  the  substance  of  the  pons,  in  which  we 
shall  afterward  trace  them. 

Wniien  the  two  pyramids  are  gently  held  apart,  it  is  said  that  some  transverse  fibres 
are  seen  passing  from  one  to  the  other,  along  the  bottom  of  the  median  furrow ;  and  it 
is  even  stated  that  there  is  a  decussation  of  their  fibres  :  this,  however,  is  only  apparent, 
and  I  cannot  here  too  particularly  caution  the  student  against  those  illusive  appearances, 
which  depend  either  upon  the  existence  of  foramina  for  the  passage  of  vessels,  or  may 
be  produced  by  pulling  about  the  scattered  fibres  in  drawing  the  parts  asunder.  It  wiU 
soon  be  shown  that  there  are  no  transverse  fibres  fiere,  and  that  there  is  no  decussation 
of  fibres  at  an  acute  angle  along  the  whole  length  of  the  anterior  pyramids,  as  was  ad- 
laitted  by  Petit,  Winslow,  Santorini,  and  others. 

The  two  halves  of  the  medulla  oblongata  are,  in  fact,  merely  applied  to  each  other, 
and  agglutinated  together.  There  is  no  decussation  excepting  at  the  point  where  the 
pyramids  emerge. 

The  Olivary  Bodies. 
Upon  the  anterior  surface  of  the  medulla  oblongata,  to  the  outer  side  of  the  anterior 
pyramids,  and  upon  a  plane  somewhat  posterior  to  them,  are  found  two  white  ovoid 
bodies  (corpora  ovata),  sometimes  projecting  in  relief;  these  are  peculiar  to  the  human 
subject,  and  are  more  prominent  in  the  foetus  and  new-born  infant  than  in  the  adult. 
They  were  first  described  by  Eustachius,  and  afterward  more  accurately  by  Vieussens, 
who,  on  account  of  their  shape,  gave  them  the  name  of  olivary  bodies  (corpora  olivaria,  c  c) ; 
they  are  much  shorter  than  the  anterior  pyramids,  being  not  more  than  six  lines  in 
length  ;  they  are  directed  obliquely  downward  and  inward.  The  upper  extremity  of  the 
olivary  body  does  not  reach  the  pons  Varolii,  but  is  separated  from  it  by  a  deep  furrow ; 
the  lower  extremity,  which  is  less  prominent  than  the  upper,  is  bound  down  by  a  bundle 
of  arched  fibres,  the  concave  borders  of  which  are  directed  upward  (processus  arciformes,e). 
The  outer  border  of  the  anterior  pyramids  and  the  series  of  nervous  filaments  which 
unite  to  form  the  hypoglossal  nerve  (9,  fig.  276)  constitute  the  internal  boundary  of  each 


704 


'NEUROLOGY. 


olivary  body ;  and  a  deep  furrow,  directed  vertically,  separates  them  on  the  outer  side 
from  the  inferior  peduncles  of  the  cerebellum  or  the  restiform  bodies.* 

It  is  of  importance  to  observe,  that  that  portion  of  the  olivary  body  which  projects  on 
the  outer  side  of  the  pyramid  is  only  the  external  half  of  the  olivary  body,  its  interned 
half  being  imbedded  in  the  substance  of  the  medulla  oblongata,  so  as  to  reach  behind  the 
anterior  pyramid,  t 

The  Posterior  SurfcLce  of  the  Medulla  Oblongata. 
This  surface  is  partly  concealed  by  the  cerebellum,  being  received  into  a  groove  on 
Fig.  271.  its  under  surface,  and  cannot  be  completely  exposed  unless  the 

medulla  oblongata  be  forcibly  bent  forward,  or  the  middle  part 
of  the  cerebellum  be  divided  vertically.  It  is  then  seen  that  the 
cord  appears  to  open  out  {t,fig.  271)  opposite  the  upper  part  of 
this  surface,  and  to  be  turned  inside  out,  so  that  the  gray  sub- 
stance is  exposed.  In  consequence  of  this  separation  of  the 
posterior  columns  of  the  cord,  there  is  left  between  them  a  shal- 
low, triangular,  or  V-shaped  depression  (;?),  the  bottom  of  which 
is  smooth,  and  forms  the  anterior  wall  of  the  fourth  ventricle  ; 
Herophilus  named  this  depression,  from  its  appearance,  the  cal- 
amus scriptorius. 

A  vertical  median  groove  corresponds  to  the  shaft  of  the  quill ; 
while  its  barbs  are  represented  by  certain  white  medullary  lines, 
which  vary  exceedingly  in  number,  and  are  not  symmetrical ; 
some  of  these  lines  are  lost  upon  the  walls  of  the  ventricle,  and 
others  turn  round  the  lateral  surface  of  the  medulla  oblongata, 
and  constitute,  in  part,  the  origin  of  the  auditory  nerves.  The 
point  of  the  pen  is  represented  by  the  very  acute  inferior  angle 
lormed  by  the  sides  of  the  depression,  which  terminates  below  in  a  cul-de-sac,  the  fos- 
settc  of  the  fourth  ventricle,  also  called  the  ventricle  of  Arantius.  According  to  some  au- 
thors, at  the  point  of  the  calamus  is  situated  the  upper  orifice  of  a  canal,  which  runs 
through  the  whole  length  of  the  spinal  cord ;  such  a  canal,  however,  does  not  exist,  but 
is,  in  fact,  produced  by  the  means  employed  to  demonstrate  it,  for  example,  by  insuffla 
tion,  by  the  introduction  of  a  probe,  or  by  the  weight  of  a  column  of  mercury.  A  slight  V 
shaped  deposite  of  corneous  matter  is  constantly  found  inserted  within  the  corresponding- 
ly-shaped bifurcation  of  the  columns  of  the  cord  :  between  the  branches  of  the  V  is  found 
the  prolongation  of  gray  substance,  which  is  continuous  with  the  gray  matter  of  the  cord. 
The  medullary  columns  which  immediately  bound  the  calamus  on  each  side,  and  which 
result  from  the  separation  of  the  elements  of  the  cord,  are  formed  by  the  posterior  me- 
dian columns  {e,fig.  269,  B  C,  and  _^^.  271),  already  described,  which  become  slightly 
enlarged  where  they  separate  from  each  other,  so  as  to  form  a  mammillary  projection, 
and  then  terminate  insensibly  upon  the  back  of  the  restiform  bodies  :  we  shall  call  the 
upper  part  of  these  columns  the  mammillary  enlargements  of  the  posterior  median  columns^ 
and  not  '■^posterior  pyramids. ''''% 

On  the  outer  side  of  these  mammillary  enlargements  are  found  the  restiform  bodies  (d, 
fig.  269,  C  ;  fig.  271),  which,  as  we  shall  afterward  describe,  pass  to  the  cerebellum,  and 
may  be  said  to  form  its  root ;  they  are  also  called  the  inferior  peduncles  of  the  cerebellum, 
or  processus  a  cerebello  ad  medullam  ohlongatam.  Ridley  named  them  the  restiform  bodies, 
or  cord-like  processes  ;  and  others,  again,  call  them  the  posterior  pyramids. 
Fig.  272.  TheJjateral  Surface  of  the  Medulla  Oblongata. 

These  present  {fig.  272),  in  front,  the  olivary  bodies  (c),  which  we 
have  already  seen  upon  the  anterior  surface.  Behind  them  are  the 
restiform  bodies  (d) ;  and,  lastly,  about  three  lines  below  the  lower 
extremity  of  each  olivary  body,  is  found  an  oblong  projection,  the 
colour  of  which  is  intermediate  between  that  of  the  white  and  that 
of  the  gray  substance  :  this  projection  is  continuous  with  the  gray 
matter  of  the  furrow,  from  which  the  posterior  roots  of  the  spinal 
nerves  arise  ;  and  Rolando,  who  first  directed  attention  to  it,  has 
named  it  the  ash-coloured  tubercle  (tuberculo  cinereo). 

The  arched  fibres,  or  processus  arciformes  {e,fig.  270),  pointed  out 
by  Santorini,  and  still  better  described  by  Rolando,  are  principally 
found  upon  the  lateral  surfaces  of  the  medulla  oblongata ;  they  con- 
sist of  filaments  of  medullary  substance,  which  vary  exceedingly  in 

*  I  do  not  say,  with  some  authors,  that  the  filaments  of  origin  of  the  glosso-pharyngeal  and  pneumogastric 
nerves  (8,  fig.  270)  bound  the  olivary  bodies  behind,  for  these  filaments  arise  from  the  inferior  peduncles  of 
the  cerebellum,  or  the  restiform  bodies,  not  from  the  furrow  between  those  peduncles  and  the  olivary  bodies 

t  In  the  body  of  a  female  who  died  at  the  Maternity,  the  left  pyramidal  and  olivary  bodies  were  not  more 
than  half  their  usual  width.  It  might  have  been  supposed  that  they  were  atrophied  ;  but  the  patient  had  ex- 
hibited no  symptom  indicative  of  so  serious  and  uncommon  a  lesion.  With  a  little  attention,  I  could  easily 
see  that  the  pyramid  was  divided  into  two  portions,  the  anterior  of  which  occupied  the  usual  position,  while 
the  posterior  covered  the  posterior  half  of  tlie  olivary  body. 

I  [The  term  posterior  pyramids  is,  nevertheless,  applied  to  these  bodies  by  many  modern  anatomists.] 


INTERNAI?  STRUCTURE  OP  THE  MEDULLA  OBLONGATA.      705 

number  and  arrangement ;  they  appear  to  arise  from  the  anterior  median  furrow  of  the 
medulla  oblongata,  to  turn  like  a  girdle  around  the  pyramidal  and  olivary  bodies,  and, 
having  reached  the  restiform  bodies,  to  pass  obliquely  upward  and  outward  to  terminate 
upon  the  sides  of  the  restiform  bodies.  These  arched  fibres  sometimes  seem  to  be  en- 
tirely wanting ;  at  other  times  they  are  collected  on  each  side  into  two  bundles  :  one 
superior,  which  turns  round  the  anterior  pyramid,  as  that  body  is  about  to  enter  the 
pons ;  the  other  inferior,  which  covers  and  circumscribes  the  lower  extremity  of  the 
olivary  body.  Lastly,  the  pyramidal  and  olivary  bodies  are  not  unfrequently  found  to  be 
completely  and  regularly  covered  by  a  thin  layer  of  circular  fibres  :  it  will  be  presently 
shown  that  these  fibres  dip  into  the  anterior  median  furrow  of  the  medulla  oblongata, 
and  reach  as  far  as  the  posterior  median  furrow.* 

Internal  Structure  of  the  Medulla  Oblongata. 
The  internal  structure  of  the  medulla  oblongata  should  be  examined  by  means  of  sec 
tions,  by  the  ordinary  method  of  dissection,  by  separating  its  elements  by  means  of  a 
jet  of  water,  and  by  dissecting  it  after  it  has  been  hardened  in  alcohol  or  boiled  in  oil. 

Sections. 

Horizontal  Sections. — Following  the  example  of  Rolando,  we  shall  examine  four  sec- 
tions of  the  medulla  oblongata. 

The  first  should  be  made  immediately  below  the  decussation  of  the  pyramids ;  the 
second,  opposite  the  middle  of  the  decussation  ;  the  third,  through  the  middle  of  the  oli- 
vary bodies  ;  and  the  fourth,  immediately  below  the  pons. 

The  first  section  presents  exactly  the  same  appearances  as  a  section  of  the  spinal  cord. 

The  second  presents  a  very  different  arrangemeirt  :  the  decussating  bundles  of  the 
pyramids  are  of  very  considerable  size,  and  occupy  the  anterior  two  thirds  of  the  sub- 
stance of  the  medulla :  their  section  represents  a  triangle  having  its  base  turned  for- 
ward, and  its  truncated  apex  backward.  The  gray  matter  is  not  circumscribed,  as  in 
the  first  section,  but  appears  to  penetrate  irregularly  into  the  white  substance  of  which 
the  remaining  part  of  the  medulla  consists.  The  white  substance  itself  has  not  the  pure 
whiteness  of  medullary  substance  ;  nor  does  the  gray  matter  resemble  that  of  the  rest 
of  the  spmal  cord,  but  it  is  of  a  yellowish-gray  colour,  and  is  much  denser. 

The  third  section  through  the  middle  of  the  olivary  bodies  {fig.  269,  C)  presents,  be- 
sides the  triangular  section  of  the  pyramidal  bodies  (i),  the  serrated  section  of  the  corpus 
dentatum  (c')  of  the  olivary  bodies  (c) ;  it  enables  us  to  form  an  accurate  idea  of  the  shape 
and  size  of  these  bodies,  which  extend  to  each  side  of  the  median  line  ;  it  shows  that 
they  are  directed  obliquely  inward  and  backward,  and  that  they  consist  of  successive 
layers,  viz.,  of  an  external  white  layer,  of  an  interrupted  yellowish  layer,  and  of  a  sec- 
ond white  layer,  which  lines  the  inner  surface  of  the  yellowish  one.  It  is  seen  that  the 
corpora  dentata  of  the  olivary  bodies  are  interrupted,  or,  rather,  open  on  the  inner  side 
towards  the  median  line,  so  as  to  admit  the  white  fibres  with  which  their  interior  is 
filled.  The  waving  gray  line  seen  on  these  sections  depends  upon  the  yellow  layer  be- 
ing frequently  folded  inward  and  outward  upon  itself;  and  from  this  appearance  the 
terms  corpwi  dentatum,  or  corps  festonne,  have  been  applied  to  the  gray  substance  of  the 
olivary  bodies.  The  remaining  part  (<£)  of  the  medulla  oblongata  consists  of  a  substance 
which  is  of  the  colour  of  coffee  mixed  with  milk,  and  which  offers  more  resistance  to 
the  knife  than  other  parts  of  the  medulla,  and  consists  neither  wholly  of  white  matter 
nor  wholly  of  gray,  but  of  a  mixture  of  both. 

The  fourth  section,  made  immediately  below  the  pons  {fig.  369,  B),  presents  a  trian- 
gular surface,  on  which  we  remark,  at  each  of  the  posterior  angles,  a  thick  white  bun- 
dle, almost  as  large  as  the  posterior  pyramidal  body,  and  which  will  be  hereafter  shown 
to  constitute  one  of  the  roots  of  the  fifth  nerve  :  these  bundles  are  also  seen  upon  the 
third  section  made  through  the  olivary  bodies,  but  they  are  much  smaller  than  in  this 
section.  The  section  of  the  two  anterior  pyramids  {b)  is  circular  at  this  point.  The 
centre  of  this  section  of  the  medulla  consists  entirely  of  a  grayish- white  or  coffee-col- 
oured substance  {d  c'),  covered  by  a  white  layer.  The  grayish-white  substance  belongs 
specially  to  the  medulla  oblongata ;  the  surrounding  white  layer  is  the  continuation  of 
the  columns  of  the  spinal  cord,  t 

The  oblique  sections  display  appearances  corresponding  with  those  of  the  horizontal 
section. 

Vertical  Section. — A  very  interesting  section  of  the  medulla  oblongata  is  a  vertical  one, 
extending  from  before  backward  through  the  median  line.  I  prefer  the  plan  of  forcibly 
separating  the  two  halves  of  the  medulla  to  that  of  dividing  it  with  a  scalpel.  By 
this  means  it  may  be  shown  that  there  are  in  the  median  line  of  the  medulla  some  an- 

*  Ought  we  to  regard  as  a  part  of  this  system  of  arched  fibres  a  small,  slender  cord  which  surrounds  the 
upper  part  of  the  anterior  pyramids,  and  which  in  other  respects  has  a  similar  arrangement  to  the  arched 
fibres  generally  % 

t  The  medulla  oblongata  of  a  child  seven  or  eight  years  old  is  much  better  adapted  for  the  examination  of 
these  sections  than  that  of  an  adult  or  old  subject,  because  the  two  substances  are  blended  in  the  latter ;  a 
stream  of  water  directed  upon  the  sections  will  greatly  assist  the  examination,  by  makiug  the  colours  more 
iistinct 

4  U 


706  NEUROLOGY.  • 

tero-posterior  fibres,  which  appear  to  me  to  vary  in  number  in  different  subjects :  fhesc 
fibres  (o,  Jig.  274)  run  from  behind  forward  through  the  whole  antero-posterior  diameter 
of  the  medulla  ;  having  reached  the  anterior  median  furrow,  they  pass  horizontally  out- 
ward to  cover  the  pyramids  and  olivary  bodies,  and  form  the  arched  fibres  already  de- 
scribed. These  antero-posterior  fibres  are  limited  below  by  the  decussating  fibres  of  the 
pyramids. 

Examination  of  the  Medulla  Oblongata  by  Dissection  under  a  Jet  of  Water,  and  when  hardened 

in  Alcohol. 

The  anterior  pyramids  may  be  separated  by  ordinary  dissection,  and  a  tolerably  accu- 
rate view  obtained  of  their  decussations  ;  and,  moreover,  the  medulla  oblongata  may  be 
divided  into  two  lateral  halves,  and  its  principal  parts  may  then  be  isolated.  The  ex- 
amination of  the  medulla  when  hardened  in  alcohol,  or  boiled  in  oil,  or  in  a  solution  of 
salt,  leads  to  important  results,  by  enabling  us  to  dissect  it  fibre  by  fibre,  and  to  trace 
these  fibres  above  and  below  their  points  of  decussation.  Together  with  these  different 
modes  of  investigation  I  have  employed  another,  viz.,  that  of  acting  upon  the  medulla 
and  its  parts  by  a  jet  of  water,  the  force  and  size  of  which  is  to  be  varied  at  pleasure, 
and  the  drops  of  which  insinuate  themselves  between  the  fibres  and  separate  them  from 
each  other.* 

If  a  stream  of  water  be  directed  upon  the  anterior  pyramids,  the  fasciculated  ar- 
rangement of  their  component  fibres,  all  of  which  are  parallel,  will  be  clearly  demonstra- 
ted ;  and  it  will  also  be  seen  that  these  two  bodies  are  not  mere  medullary  bands,  but 
are  two  three-sided  bundles  occupying  an  angular  groove  between  and  in  front  of  the  two 
ohvary  bodies  {fig.  269,  C). 

The  decussation  of  the  anterior  pyramids  demands  attention,  as  one  of  the  most  impor- 
tant points  in  the  anatomy  of  the  cerebro-spinal  axis. 

On  examining  the  anterior  median  groove  of  the  medulla  oblongata  (see^^*.  270, 276), 
it  will  be  found  that,  at  a  distance  from  the  pons  Varolii  of  about  ten  lines  (Gall  says  an 
inch  and  some  lines),  the  anterior  pyramids  divide  into  three  or  four  bundles,  which  al- 
ternately interlace  in  a  regular  manner  (below  n),  so  as  to  form  a  plaited  structure  of  from 
two  to  four  lines  in  length.  Is  this  decussation  only  apparent  1  and  if  so,  does  the  ap- 
pearance result,  as  has  been  said,  from  the  traction  of  parallel  fibres  in  opposite  direc- 
tions 1  or  do  the  pyramids  commence  by  alternate  bundles  arising  from  each  side  of  the 
middle  line,  and  does  this  alternate  arrangement  occasion  the  appearance  of  a  decussa- 
tion 1  or,  lastly,  do  the  right  and  left  pyramids  actually  cross  like  the  limbs  of  the  letter  X 1 

On  consulting  the  various  authorities  on  this  subject,  it  is  found  that  the  decussation 
of  the  pyramids,  first  pointed  out  by  Aretaeus,  renoticed  by  Fabricius  Hildanus,  and  de- 
monstrated by  Mistichellit  and  Pourfour  Dupetit,t  has  been  admitted  by  Santorini,  Wins- 
low,  Lieutaud,  Duverney,  Scarpa,  and  Soemmering ;  and  that  the  opposite  opinion  has 
been  maintained  by  Morgagni,  Haller,  Vic  d'Azyr,  Sabatier,  Boyer,  Cuvier,  Chaussier, 
and  Rolando.iJ  As  to  Gall  and  Spurzheim,  they  do  not  seem  to  have  had  a  decided 
opinion  upon  this  point ;  for,  after  having  appeared  to  admit  the  decussation  in  some 
passages  of  their  work,  they  say  elsewhere  that  the  small  cords  of  the  pyramids  do  not 
form  a  true  decussation,  but  merely  intersect  and  pass  over  each  other  obliquely. 

In  order  to  settle  the  question  of  decussation,  I  submitted  the  medulla  oblongata  to 
the  action  of  a  jet  of  water  upon  both  its  anterior  and  posterior  surfaces  ;  and  by  then 
examining  it  from  behind  forward,  I  was  able  to  ascertain  that  the  right  and  left  p)Tam- 
idal  bundles  do  most  evidently  decussate  (a,  fig.  273) ;  that  this  decussation  is  effect- 
ed, not  only  from  side  to  side,  but  also  from  before  backward  (i,  fig.  274) ;  that  the  left 
pyramidal  bundle  (i)  passes  downward  to  the  right  side  and  backward  (w),  traverses  the 
gray  matter  of  the  cord,  and  becomes  continuous  with  the  right  lateral  column  of  the 
cord,  and  vice  versa  ;  and,  lastly,  that  the  anterior  pyramids  are  not  in  the  slightest  de- 
gree continuous  with  the  anterior  columns  of  the  spinal  cord. 

The  Olivary  Bodies. — ^When  the  anterior  pyramids  are  removed,  it  is  seen  that  the 
olivary  bodies  {d,  figs.  273,  274)  do  not  consist  merely  of  the  prominent  masses  which 
project  beyond  and  on  the  outer  side  of  the  anterior  pyramids,  but  that  they  extend  in- 
ward to  the  median  hne  behind  the  pyramids,  which  are  received  in  a  slight  concavity 
formed  by  the  anterior  surfaces  of  the  olivary  bodies  {fig.  269,  C).  This  arrangement  is 
very  evident,  without  any  preparation,  in  anencephalous  infants,  or  in  such  as  are  born 

*  If  we  employ  a  stream  of  water  in  the  eiamination  of  a  fresh  medulla  oblongata,  it  may  easily  be  con- 
ceived that  the  results  will  be  much  more  conclusive  than  if  we  had  thus  examined  one  which  had  already 
>  been  subjected  to  different  modes  of  preparation  that  may  have  altered  its  structure. 

t  Trattato  dell'  Apoplessia,  1709.  t  Letters  d'un  Med6cin  des  Hdpitaux,  1710. 

<t  Of  all  who  have  denied  the  reality  of  the  decussation,  Rolando  appears  to  me  to  have  opposed  the  doctrine 
vith  the  greatest  force.    He  examined  the  subject  with  the  greatest  attention  ;  he  made  horizontal  sections 

■  of  the  medulla  oblongata,  but  he  could  never  see  anything  more  than  the  alternate  origin  of  the  fasciculi  which 
.  eoastitute  the  anterior  pyramids ;  he  could  never  find  that  the  bundles  of  the  right  side  passed  over  to  the 

left,  and  vice  versd.     In  reply  to  the  objection,  that  without  admitting  the  decussation  it  is  iinpossible  to  ac- 

■  count  for  the  cross  effects  of  injuries  or  diseases  of  the  brain,  he  states  that  these  are  explained  by  the  inti- 
mate union  between  the  optic  thalanii  and  tubercula  quadrigemina  of  the  two  sides,  and  between  the  two  halves 
of  the  pons  Varolii  and  medulla  oblongata.  The  error  of  Rolando  evidently  arose  from  his  attaching  such  ei- 
Husive  importance  to  sections,  as  a  means  of  determining  the  structure  of  the  medulla  ob\ongata. 


INTERNAL   STRUCTURE    OF  THE   MEDULLA    OBLONGATA.  707 

with  very  imperfectly-developed  brains  ;  the  situation  of  the  atrophied  pyramids  is  then 
occupied  by  two  tracts  of  gray  matter,  and  the  olivary  bodies,  more  developed  than  usual, 
reach  as  far  as  the  median  line. 

When  a  jet  of  water  is  directed  against  the  median  line  between  the  olivary  bodies, 
it  encounters  a  white  and  very  dense  tissue,  upon  which  it  produces  little  effect.* 

As  soon  as  this  tissue  has  been  removed  with  the  knife,  the  water  insinuates  itself 
mto  the  substance  of  the  olivary  bodies,  which,  as  we  have  seen,  are  open  towards  the 
inner  side  ;  each  olivary  body  is  then  spread  out,  its  anterior  half  is  turned  outward,  and 
assumes  the  appearance  of  a  dense  yellowish  layer  folded  upon  itself,  like  a  leaf  while 
within  its  bud ;  after  some  white  lamellae  are  removed  by  the  action  of  the  water,  the 
posterior  half  is  exposed,  and  displays  a  similar  appearance  to  that  of  the  anterior  half 
Rolando  compares  the  arrangement  of  this  yellow  folded  layer,  or  corpus  dentatum  of 
the  olivary  body,  to  a  flattened  purse  {borsa  appiattita),  the  neck  of  which  is  open,  some- 
what constricted,  and  directed  backward  and  towards  the  median  line. 

Gall  and  Spurzheim  regarded  the  olivary  bodies  as  ganglia,  but  these  anatomists  ap- 
pear to  me  to  have  singularly  misappUed  the  term  ganglion,  which  they  have  given  to 
such  dissimilar  parts  as  the  olivary  bodies,  the  corpora  striata,  and  the  tuber  annulare. 

Lastly,  by  directing  the  stream  of  water  against  the  median  line,  and  by  assisting  its 
action  by  gently  drawing  the  parts  asundei.  the  medulla  oblongata  becomes  divided  into 
two  perfectly  similar  halves,  excepting  opposite  the  decussation.  A  beautiful  prepara- 
tion may  thus  be  made,  exhibiting  the  separation  of  the  two  halves  of  the  medualla  ob- 
longata and  spinal  cord,  and  leaving  the  decussation  of  the  anterior  pyramids. 

It  appears,  then,  on  the  one  hand,  that  the  anterior  pyramids  are  not  formed  by  the 
anterior  columns  of  the  spinal  cord ;  and,  on  the  other  hand,  that  the  posterior  columns 
of  the  cord  become  separated  from  each  other  behind  when  they  have  reached  the  me- 
dulla oblongata.  What,  then,  becomes  of  the  white  bundles  of  the  cord  in  the  medulla  ob- 
longata 1 

Having  arrived  opposite  the  neck  of  the  bulb,  the  white  matter  of  the  cord  is  divided 
into  two  bundles  :  one  anterior,  which  forms  the  anterior  pyramid  {b.  Jig.  273),  and  may  be 
called  the  cerebral  bundle,  because  it  passes  up  (i')  to  the  brain  ;  the  other  posterior,  oi 
the  restiform  body  (c  e),  which  may  be  called  the  peduncle  of  the  cerebellum,  because  it  is 
exclusively  intended  (w)  for  that  organ  ;  the  former  is  composed  of  white  bundles,  which 
emerge  from  the  interior  of  the  spinal  cord,  and  the  latter  of  the  anterior  columns,  and 
of  the  remaining  white  bundles  of  the  cord.  The  olivary  bodies  {d)  are  situated  between 
these  two  sets  of  white  fibres. 

When,  by  means  of  the  stream  of  water,  the  anterior  pyramids  and  the  restiform 
bodies  have  been  removed,  it  is  seen  that  each  half  of  the  medulla  oblongata  is  formed 
principally  of  a  very  dense  nucleus,  consisting  of  a  mixture  of  gray  and  white  substances. 
This  nucleus,  or  fasciculus  of  re-enforcement  of  the  medulla  oblongata,  which  we  shall  call 
the  unnamed  fasciculus  (faisceau  innomini)  of  the  medulla,  commences  opposite  the  de- 
cussation of  the  pyramids  by  a  narrow  extremity,  increases  in  size  as  it  proceeds  up- 
ward, passes  above  {I,  fig.  274),  i.  e.,  deeper  than  the  pons,  and  becomes  continuous,  as 
we  shall  afterward  see,  with  the  corresponding  optic  thalamus.  Each  half  of  the  medul- 
la oblongata  has  its  fasciculus  of  re-enforcement,  of  which  the  internal  surface,  viz.,  that 
turned  towards  the  middle  line,  corresponds  to  the  fasciculus  of  the  opposite  side,  but 
is  separated  from  it  by  the  white  fibres  {p,fig.  274)  already  described  (p.  706)  as  passing 
horizontally  from  before  backward,  in  the  median  line  of  the  medulla.  The  posterior 
surface  of  these  fasciculi  {p,fig.  271)  constitutes  the  anterior  wall  of  the  fourth  ventricle. 
The  corresponding  peduncles  of  the  cerebellum,  or  the  restiform  bodies,  embrace  them 
on  the  outside,  and  form,  as  it  were,  grooves  for  them. 

On  examining  thoroughly  the  internal  or  median  surface  of  each  re-enforcing  fascicu- 
lus of  the  bulb,  it  is  found  that  there  are  two  vertical  bands  upon  that  surface,  one  an- 
terior, the  other  posterior ;  and  that  the  fibres  which  pass  horizontally  from  before  back- 
ward in  the  median  line  of  the  medulla  oblongata  are  situated  between  the  bands  of  the 
right  and  left  sides. 

Each  fasciculus  of  re-enforcement  is  divided  above  into  two  parts,  one  of  which  forms 
the  centre  of  the  corresponding  restiform  body,  while  the  other  becomes  continuous  with 
the  optic  thalamus  above  the  pons  Varolii. 

I  have  not  alluded  to  the  olivary  fasciculi  admitted  by  some  anatomists,  for  the  white 
bundles  so  called  do  not  even  come  from  the  olivary  body,  but  form  the  continuation  of 
the  lateral  columns  of  the  spinal  cord,  which  embrace  the  olivary  bodies  on  the  outer 
side,  without  being  re-enforced  by  any  bundles  derived  directly  from  them.t 

*  I  have  frequently  been  led  to  regard  the  white  medullary  substance  which  is  situated  between  the  olivary 
bodies,  and  passes  into  each  of  them,  as  a  transverse  commissure,  which  might  be  called  the  commissure  ot 
the  olivary  bodies. 

t  [The  bundles,  named  faisccaux  innommin^s  in  the  text  (fasciculi  teretes  of  some  other  authors),  which  M. 
Cruveilhier  describes  as  taking  their  rise  at  the  lower  end  of  the  medulla  oblongata,  are  more  generally  con- 
sideied  to  be  prolonged  from  the  lateral  columns  of  the  cord  ;  and  on  comparing  the  statements  of  recent  in- 
quirers concerning  the  anatomy  of  the  medulla  oblongata,  the  following  appears  to  be  the  arrangement  which 
the  columns  of  the  cord  undergo  in  passing  through  it,  viz.,  the  posterior  columns  (including  the  postonor  me 
diau  fasciculi,  which  correspond  with  the  posterior  pyramids)  separate  laterally f'om  one  another  (f,figs.Zi3, 


708  NEUROLOGY. 

Development  of  the  Spinal  Cord. 

As  soon  as  the  spinal  cord  has  passed  through  its  original  condition  of  an  almost 
transparent  pulp,  it  assumes  the  appearance  of  a  lamina,  the  edges  of  which  are  rolled 
back  upon  themselves  so  as  to  enclose  a  canal,  continuous  with  the  cavity  of  the  fourth 
ventricle,  which  might  be  regarded  as  the  expanded  extremity  of  the  canal.  This  canal 
is  narrowed  along  the  middle  by  the  reflection  of  the  pia  mater  into  it :  it  is  thus  con- 
verted into  two  canals,  the  walls  of  which  are  at  first  thin,  but  afterward  increase  in 
thickness,  gradually  encroach  upon  the  caliber  of  the  canals,  which  finally  disappear  be- 
tween the  sixth  and  seventh  month.  At  this  period  a  thin,  white,  outer  layer  covers  the 
whole  medulla :  the  posterior  median  columns  are  very  large,  and  of  a  white  colour, 
while  the  antero-lateral  columns  are  still  semi-transparent,  the  gray  matter  is  soft  and 
diffluent,  like  a  pulp  ;  and,  by  the  slightest  insufllation,  a  canal  may  be  formed  along  the 
centre  of  each  half  of  the  cord. 

The  spinal  cord  occupies  the  whole  length  of  the  vertebral  canal  until  the  third  month ; 
but  after  this  time,  its  lower  extremity  becomes  relatively  higher  up  to  the  period  of 
birth,  when  it  corresponds  to  the  second  lumbar  vertebra. 

The  spinal  cord  is  larger,  in  proportion  to  the  brain,  during  the  early  periods  of  foetal 
hfe,  than  afterward.  The  more  rapid  development  of  the  brain,  at  later  periods,  gives 
that  organ  the  advantage. 

From  studying  the  development  of  the  spinal  cord,  Tiedemann  infers  that  the  white 
substance  exists  before  the  gray,  and  therefore  that  the  latter  cannot  be  the  nutritious 
organ  or  matrix  of  the  white  substance,  as  Gall  had  affirmed. 

It  is  quite  certain  that  the  white  parietes  of  the  medullary  canal  are  developed  pre- 
viously to  the  gray  matter. 

Development  of  the  Medulla  Oblongata. 

During  the  first  three  months  of  intra-uterine  life,  the  upper  limit  of  the  medulla  ob- 
longata is  not  defined,  because  there  is  no  pons  Varolii.  The  foetal  brain,  therefore,  in 
this  condition,  resembles  the  brains  of  birds,  reptiles,  and  fishes.  The  transverse  fibres 
of  the  pons  make  their  appearance  during  the  fourth  month,  and  the  upper  limit  of  the 
medulla  oblongata  is  then  established. 

The  two  halves  of  the  medulla  oblongata  are  perfectly  distinct,  and  each  half  is  divi- 
ded into  three  columns  :  one  for  the  brain  properly  so  called,  viz.,  the  anterior  pyramidal 
bundle  ;  another  for  the  tubercula  quadrigemina,  which  may  be  called,  with  Tiedemann, 
the  olivary  bundle,  remembering,  at  the  same  time,  that  this  term  has  a  very  diiferent 
meaning  from  what  was  attached  to  it  by  Gall ;  and  a  third  or  cerebellar  bundle,  which 
is  the  restiform  body. 

The  anterior  pyramidal  bodies  are  at  first  flattened  like  those  of  mammalia,  but  during 
the  latter  months  they  acquire  their  characteristic  size  and  prominence.  In  the  medulla 
oblongata  of  a  foetus,  from  the  seventh  to  the  ninth  month,  the  anterior  pyramids  are  of 
a  reddish-gray  colour,  while  the  anterior  columns  of  the  spinal  cord  are  as  white  as  they 
appear  afterward.  Those  pyramids,  therefore,  are  not  the  continuation  of  the  anterior 
columns  of  the  cord. 

The  decussation  of  the  pyramids  is  perfectly  distinct  after  the  fourth  week  of  foetal 
existence.* 

The  olivary  bundles  of  Tiedemann,  which  are  situated  to  the  outer  side  of  the  anterior 
pyramids,  and,  like  them,  traverse  the  pons,  gain  the  sides  of  the  tubercula  quadrigemina, 
beneath  which  they  form  an  arch,  which  constitutes  the  upper  wall  of  the  aqueduct  of 
Sylvius.  The  olivary  bodies,  which  are  wanting  in  birds,  reptiles,  and  fishes,  do  not  ap- 
pear until  the  end  of  the  sixth  or  the  commencement  of  the  seventh  month  of  foetal  life. 

The  cerebellar  bundles,  or  restiform  bodies,  are  perfectly  distinct  from  the  preceding. 
The  small  manmiillated  bundles  which  bound  the  sides  of  the  posterior  longitudinal 
groove  can  also  be  distinguished  in  the  foetus. 

Comparative  .Anatomy  of  the  Spinal  Cord. 
Mammalia. — The  spinal  cord  of  mammalia  precisely  resembles  that  of  the  human  sub- 

274),  and  enter  the  cerebellum,  forming  the  principal  part  of  its  inferior  peduncle  (n).  The  fibres  of  the  lat- 
eral columns  are  disposed  of  in  three  ways:  1.  A  part  of  thfem  cross  the  median  plane  to  the  opposite  side  (m. 
Jig.  273),  and  form  the  chief  part  of  the  pyramidal  body  (A)  of  that  side.  2.  Another  set  join  the  inferior  pe- 
duncle of  the  cerebellum.  3.  The  remainin<f  fibres  are  continued  along  the  floor  of  the  fourth  ventricle  l.p,fig 
271),  as  the  fasciculi  innominati  or  fasciculi  teretes.  The  anterior  columns  (a,  fig.  273)  of  the  cord,  on  enter- 
ing the  medulla  oblongata,  are  thrown  aside  by  the  decussating  fibres  coming  from  the  lateral  columns,  and 
then  one  portion  of  each  anterior  column  forms  the  outer  part  of  the  coiTesponding  pyramid  (i) ;  another  por 
tion  {c,fig.  274)  passes  partly  behind  and  partly  on  the  outer  side  of  the  olivary  body,  and  is  then  chiefly  con 
tinued  into  the  fillet  (A)  ;  the  remaining  part  passes  into  the  cerebellum,  joining  its  inferior  peduncle  (n) 
The  connexion  of  the  cerebellum  with  the  anterior  columns  of  the  cord  was  pointed  out  by  Mr.  Solly. — (Phil. 
Trans.,  1836,  p.  567.)  Arnold  describes  the  posterior  pyramids  (fasciculi  gracilea)  as  passing  into  the  crura 
cerebri.  For  farther  details  on  the  anatomy  of  the  medulla  oblongata,  the  reader  is  referred  to  Arnold's 
Bemerkungen  itber  den  Bau  des  Hirns  und  Ruckenmarks,  Zurich,  1838 ;  also  his  Icones  Anatomica,  fasc.  i. , 
and  to  a  paper  by  Dr.  J.  Reid  in  the  Edtn.  Med.  and  Surg.  Journ.  for  January,  1841.] 

*  [The  fourth  or  fifth  month,  accordino-  to  Tiedemann  ;  though  in  one  part  of  his  work  "  week"  has  been, 
by  an  error,  printed  for  "month."] 


COMPARATIVE    ANATOMY    OF   THE   MEDULLA    OBLONGATA.  709 

ject :  its  length,  its  size,  its  enlargements,  are  exactly  proportioned  to  the  size  and  ac- 
tivity of  the  muscles,  and  to  the  sensibility  of  the  organs  with  which  it  is  connected  by 
means  of  the  nerves. 

Birds. — The  spinal  cord  in  birds  is  proportionally  both  longer  and  larger  than  in  other 
animals  ;  and  this  has  reference  to  the  enormous  muscular  effort  required  in  flying.  It 
presents  two  great  enlargements  ;  one  of  these  corresponds  to  the  wings,  and  the  other, 
which  is  larger,  and  contains  a  ventricle,  corresponds  to  the  lower  extremities ;  this 
ventricle  was  known  to  Steno,  who  described  it  under  the  name  of  the  rhomboidal  sinus. 

According  to  Nicolai  {Dissertatio  de  Medulla  Spinali  Avium,  Halle,  1811)  and  Tiede- 
mann,  the  spinal  cord  of  birds  contains  a  central  canal,  which  is  lined  by  a  thin  layer  of 
gray  matter,  not  only  in  the  embryo,  but  also  in  the  adult. 

Reptiles.- — In  all  reptiles  the  spinal  cord  contains  a  canal,  which  is  lined,  according  to 
Tiedemann,  by  a  thin  layer  of  gray  substance.  In  the  batrachian  reptiles  (the  toad,  frog, 
&c.),  the  spinal  cord  occupies  only  the  anterior  or  upper  part  of  the  vertebral  canal.  M. 
Desmoulins  says  (t.  i.,  p.  187)  that  the  gray  matter  in  these  species  surrounds  the  white 
substance.    This  opinion  appears  to  me  to  be  erroneous. 

In  ophidian  reptiles  (serpents),  the  spinal  cord  occupies  the  whole  length  of  the  verte- 
bral canal ;  there  is  no  gray  matter,*  but  its  place  is  occupied  by  a  fluid,  so  that  each 
half  of  the  medulla  contains  a  canal. 

In  the  saurians  (crocodiles,  lizards),  the  spinal  cord  is  slender,  of  almost  uniform  size 
throughout,  and  occupies  the  whole  length  of  the  vertebral  canal. 

The  spinal  cord  of  the  chelonian  (tortoises,  &c.)  is  the  most  remarkable  of  all,  as  re- 
gards its  shape,  and  is  peculiarly  illustrative  of  the  law  which  regulates  the  dimensions 
of  this  organ.  There  are  three  fusiform  enlargements  separated  from  each  other  by  two 
very  narrow  portions  ;  the  middle  enlargement  corresponds  to  the  upper  extremities,  and 
the  inferior  one  to  the  lower  extremities  ;  the  first  constriction  corresponds  to  the  neck, 
the  second  to  the  thorax. 

Fishes. — In  all  f^hcs  the  spinal  cord  occupies  the  entire  length  of  the  vertebral  canal. 
It  is  of  uniform  size  in  its  anterior  five  sixths,  but  diminishes  like  a  cone  in  the  posterior 
sixth.  There  is  no  gray  matter,t  so  that  the  cord  is  hollow.  According  to  Arsaky 
(^Dissert,  de  Piscium  Cerebro)  and  Tiedemann,  the  medullary  canal  is  lined  by  a  thin  layer 
of  gray  matter. 

The  lophius  piscatorius  and  the  male  tetrodon  present  remarkable  anatomical  peculi- 
arities ;  in  the  lophius,  the  spinal  cord  is  diminished  in  size  opposite  the  third  cervical 
vertebra ;  all  at  once  it  becomes  extremely  slender,  and  then  terminates  in  a  point  op- 
posite the  eighth  cervical  vertebra.  Twenty-six  pairs  of  nerves  arise  from  the  enlarged 
portion,  and  only  five  or  six" pairs  from  the  slender  portion.  In  the  tetrodon  there  is  no 
spinal  cord,  properly  so  called,  or,  rather,  this  part  of  the  cerebro-spinal  axis  is  reduced 
to  a  medulla  oblongata,  from  which  arise  thirty-two  pairs  of  nerves. 

From  these  facts,  it  follows  that  the  length  and  size  of  the  spinal  cord  bear  an  exact 
proportion  to  the  muscular  power  and  sensibility  of  the  parts  supplied  by  it ;  and  farther, 
that  the  gray  matter  of  the  cord  is  not  nearly  so  important  as  the  white  substance,  since 
it  is  absent  in  a  great  number  of  species.  J 

Comparative  Anatomy  of  the  Medulla  Oblongata. 

In  the  mammalia  the  medulla  oblongata  is  constructed  upon  the  same  plan  as  in  the 
human  subject,  but  the  anterior  pyramids  are  much  smaller,  and  the  olivary  bodies  ap- 
pear to  be  completely  effaced.  The  tubercula  cinerea  of  Rolando  exist  only  in  man ; 
in  whom  alone  do  we  find  those  white  streaks  of  medullary  substance  upon  the  anterior 
wall  of  the  fourth  ventricle,  which  are  regarded  as  forming,  at  least  in  part,  the  origins 
of  the  auditory  nerves. 

The  medulla  oblongata  of  birds  and  reptiles  presents  no  striking  peculiarities.  In  the 
different  species  its  size  is  always  in  proportion  to  that  of  the  fifth,  and  especially  the 
eighth  pair  of  nerves,  which  take  their  origin  from  this  part. 

In  fishes  a  peculiar  pair  of  lobes  correspond  to  the  medulla  oblongata ;  these  lobes  were 
for  a  long  time  erroneously  supposed  to  be  the  lateral  lobes  of  the  cerebellum,  and  have 
thus  led  to  much  obscurity  concerning  the  anatomy  of  the  encephalon  in  these  animals. 
Desmoulins  calls  them  the  lobes  of  the  fourth  ventricle ;  we  shall  call  them  the  lobes  of 
the  eighth  pair  of  nerves.  In  the  ray  and  sturgeon  this  lobe  is  so  highly  developed,  that 
it  forms  half  of  the  encephalic  mass.  In  the  carp,  besides  the  lateral  lobes  which  are 
traversed  by  some  white  fibres,  there  is  also  a  median  lobe.  Moreover,  as  a  general 
rule,  whenever  the  spinal  cord  has  to  furnish  any  nerves,  there  is  an  enlargement  or  a 
lobe.  In  the  torpedo,  in  which  the  eighth  pair  of  nerves  are  of  enom^ous  size,  and  sup- 
ply the  electrical  organ,  these  lateral  lobes  are  in  an  extraordinary  degree  developed.  In 
the  trigla  there  are  certain  small  lobes  behind  the  cerebellum,  which  correspond  to  the  pe- 
culiar digitiform  prolongations  serving  as  organs  of  progression  in  the  animals  in  question. 

*  [The  spinal  cord  of  serpents  forms  no  exception  to  the  general  rule  ;  gray  matter  has  been  recognised  in 
it,  as  in  the  cord  of  other  vertebrated  animals.  The  same  is  true  of  fishes.— (See  Leuret,  Anatoime  Com- 
parie  du  Systime  Nerveux,  ^c,  Paris,  1839.)]  t  See  note,  siipru.  t  See  note,  supra. 


71©  NEUROLOGY.  . 

The  olivary  bodies  are  most  highly  developed  in  the  human  subject ;  they  exist  also, 
but  are  very  small,  in  some  mammalia ;  they  disappear  in  birds,  reptiles,  and  fishes.  I 
consider  the  olivary  bodies  as  lobes  in  a  rudimentary  state. 


THE  ISTHMUS  OF  THE  ENCEPHALON. 

General  Description  and  Division. — The  Pons  Varolii  and  Middle  Peduncles  of  the  Cere- 
bellum— the  Peduncles  of  the  Cerebrum — the  Superior  Peduncles  of  the  Cerebellum  and  the 
Valve  of  Vieussens — the  Corpora  Quadrigemina. — Internal  Structure  of  the  Isthmus,  viz., 
of  its,  Inferior,  Middle,  and  Superior  Strata. — Sections. — Development. — Comparative 
Anatomy. 

I  SHALL,  with  Ridley,  apply  the  term  isthmus  of  the  encephalon  to  that  narrowed 'and 
constricted  portion  of  the  encephalic  mass  which  is  situated  between  the  cerebrum,  cere- 
bellum, and  medulla  oblongata,  which  corresponds  to  the  free  margin  of  the  tentorium 
cerebelli,  and  comprises  the  pons  Varolii  and  middle  peduncles  of  the  cerebellum,  the 
peduncles  of  the  cerebrum,  the  tubercula  quadrigemina,  the  superior  peduncles  of  the 
cerebellum,  and  the  valve  of  Vieussens. 

The  isthmus  of  the  encephalon  is  the  common  point  of  union  between  the  three  great 
divisions  of  the  cerebro-spinal  axis,  viz.,  the  medulla  spinalis,  the  cerebrum,  and  the 
cerebellum.  It  contains  within  it  the  media  by  which  they  all  communicate,  or,  as  it 
may  be  said,  the  elements  of  each  reduced  to  their  most  simple  expression. 

It  is  of  a  cuboid  form,  and  therefore  presents  six  surfaces  for  our  consideration  : 

An  inferior  surface  (fig.  276),  on  which  we  observe  the  pons  Varolii,  or  tuber  annulare 
(d),  the  middle  peduncles  of  the  cerebellum  (m),  and  the  peduncles  of  the  cerebrum  (//). 

A  superior  surface  {fig.  271),  which  is  covered  by  the  superior  vermiform  process  of 
the  cerebellum,  by  the  velum  interpositum,  and  by  the  posterior  border  of  the  corpus  cal- 
losum.  In  order  to  expose  this  surface,  supposing  the  brain  to  be  with  its  base  upward, 
the  cerebellum  must  be  turned  forward,  and  the  pia  mater  should  be  separated,  taking 
care  to  lift  up  with  it  the  pineal  gland.  Proceeding  from  before  backward,  the  following 
parts  come  into  view:  the  tubercula  quadrigemina  (fg),  resting  upon  them  the  pined 
gland  (c),  the  superior  peduncles  of  the  cerebellum  (shown  in  cut  at  r ;  also  r,  fig.  272), 
and  the  valve  of  Vieussens  il,fig.  271). 

The  lateral  surfaces  {fig.  272)  are  each  divided  into  two  distinct  parts  or  stages,  by  a 
furrow  which  runs  from  before  backward  (the  lateral  furrow  of  the  isthmus) ;  the  inferior 
stage  consists  of  the  pons  Varolii  (a)  and  the  middle  peduncles  of  the  cerebellum  (m), 
while  the  superior  is  narrower,  lies  closer  to  the  median  line  than  the  preceding,  and 
presents  a  triangular  fasciculus  (A),  having  its  base  directed  downward,  and  its  apex  turn- 
ed upward,  so  as  to  reach  the  corresponding  inferior  quadrigeminous  tubercle  or  testis  {g). 

The  anterior  surface  of  the  isthmus  is  continuous  with  the  optic  thalami  {s,  fig.  272). 

The  posterior  surface  is  much  narrower  than  the  anterior,  and  is  continuous  with  the 
base  of  the  medulla  oblongata. 

We  shall  examine  the  several  parts  of  the  isthmus  in  the  following  order :  the  pons 
Varolii  and  middle  peduncles  of  the  cerebellum,  the  peduncles  of  the  cerebrum,  the  superior 
peduncles  of  the  cerebellum,  the  valve  of  Vieussens,  and  the  tubercula  quadrigemina.  The  in- 
ferior peduncles  of  the  cerebellum  have  been  already  described  with  the  rest  of  the  medulla 
oblongata,  under  the  name  of  the  restiform  bodies. 

The  Pons  Varolii  and  Middle  Peduncles  of  the  Cerebellum. 

The  pons  Varolii,  or  tuber  annulare,*  is  that  white  cuboid  eminence  {d,  fig.  276)  situa- 
ted between  the  cerebrum  and  cerebellum,  upon  the  base  of  the  encephalon,  and  form- 
ing, as  it  were,  its  centre  (mesocephale,  Chauss. ;  nodus  encephali,  Scemm.).  From  this 
centre  the  several  parts  proceed  as  follows :  backward,  the  medulla  oblongata  (e) ;  for- 
ward, two  thick  white  bundles,  which  pass  into  the  brain,  and  form  the  anterior  or  cere- 
bral peduncles  {ff);  laterally,  two  thick  bundles,  which  enter  the  cerebeUum,  and  are 
named  the  posterior  peduncles,  or  middle  cerebellar  peduncles  {m). 

The  pons  Varolii,  the  cerebral  and  cerebellar  peduncles,  and  the  medulla  oblongata 
proper,  are  together  called  the  medulla  oblongata  by  some  authors  ;  several  of  the  older 
anatomists,  in  fact,  compared  the  pons  to  the  body  of  an  animal,  of  which  the  anterior 
peduncles  represented  the  arms ;  the  posterior,  the  legs ;  and  the  medulla  oblongata 
proper,  the  tail ;  and  hence  the  terms  still  in  use  of  the  arms,  legs,  and  tail  of  the  so- 
called  medulla  oblongata.  It  was  Varolius  who  compared  this  part  to  a  bridge,  under 
which  the  several  branches  of  a  stream,  supposed  to  be  represented  by  the  peduncles  and 
the  medulla  oblongata,  joined  each  other ;  hence  the  terms  pmis  Varolii  and  pons  cerebelli. 

The  pons  is  free  below,  but  is  blended  above  with  the  upper  portion  of  the  isthmus  ; 
it  is  bounded  in  front  by  the  peduncles  of  the  cerebrum,  and  behind  by  the  meduUa  ob- 
longata ;  and  it  is  continuous,  laterally,  with  the  middle  peduncles  of  the  cerebellum  {m), 

*  The  term  tuber  annulare  is  derived  from  the  fact  that  this  part  of  the  enceohalon  seems  to  embrace  tb« 
several  prolongations  of  the  medulla  oblongata  like  a  ring. 


THE  PEDUNCLES  OP  THE  CEREBRUM,  ETC.  711 

forming  with  them  but  one  system  of  fibres ;  its  lateral  boundaries  are,  therefore,  alto- 
gether artificial. 

The  size  of  the  pons,  which  is  very  considerable  in  the  human  subject,  is  always  in 
relation  with  the  development  of  the  lateral  lobes  of  the  cerebellum ;  comparative  anat- 
omy, embryology,  and  the  study  of  malformations  completely  establish  this  fact.* 

Its  inferior  surface  is  covered  by  the  pia  mater,  which  can  be  easily  stripped  off;  it 
rests  upon  the  anterior  part  of  the  basilar  groove,  and  slopes  backward  and  downward 
like  the  incl»ed  plane  of  that  groove. 

It  presents  along  the  median  line  a  slight  furrow,  which  is  broader  in  front  than  be- 
nind,  and  corresponds  to  the  basilar  artery :  this  groove  appears  as  if  it  were  caused  by 
the  presence  of  the  artery ;  nevertheless,  I  must  say,  that  not  unfrequently  the  basilar 
artery  is  found  to  deviate  to  one  side  or  the  other,  or  to  be  more  or  less  tortuous,  and 
yet  that  the  median  groove  is  as  distinctly  marked  as  usual. 

I  beUeve  there  is  good  ground  for  entertaining  the  opinion  that  this  groove  results  from 
the  prominence  of  the  anterior  pyramids,  which  raise  up  the  surface  of  the  pons  on  each 
side  of  the  median  line. 

The  inferior  surface  of  the  pons  presents  certain  transverse  bundles  or  fibres,  which 
appear  to  cross  each  other  at  very  acute  angles,  and  which,  according  to  Rolando,  may 
be  divided  into  three  sets  :  superior  bundles,  which  turn  upward,  to  constitute  the  upper 
part  of  the  middle  peduncles  of  the  cerebellum ;  inferior  bundles,  which  pass  transversely 
outward ;  and  middle  bundles,  which  are  directed  obliquely  downward  and  outward,  pass 
in  front  of  the  inferior  bundles,  and  then  form  the  anterior  border  of  the  cerebellar  pedun- 
cles. The  origin  of  the  fifth  pair  of  nerves  is  between  the  superior  and  middle  sets  of 
fibres.     Not  uafrequently  the  middle  bundles  are  not  to  be  seen. 

It  follows,  therefore,  that  the  middle  peduncles  of  the  cerebellum  are  merely  the  trans- 
verse fibres  of  the  pons  condensed  and  twisted  upon  themselves.  The  pons  and  these 
peduncles  of  the  cerebellum  constitute  one  and  the  same  system  of  fibres.  We  might 
therefore,  with  Gall,  designate  the  pons  and  the  middle  peduncles  of  the  cerebellum  as 
the  commissure  of  the  cerebellum,  or  corpus  callosum  of  the  cerebellum. 

The  Peduncles  of  the  Cerebrum. 

The  peduncles  of  the  cerebrum  (//,  fig.  276),  sometimes  regarded  as  prolongations  of 
the  cerebrum  to  the  medulla  oblongata  ( processus  cerebri  ad  medullam  oblongatam,  ad  pon- 
tem  Varolii),  sometimes  as  the  arms,  legs,  or  thighs  of  the  cerebrum  {brachia,  crura,  femo- 
ra, cerebri),  and  by  others  as  prolongations  of  the  medulla  towards  the  cerebrum  (proces- 
sus medullm  oblongata  ad  cerebrum),  are  two  thick,  white,  fasciculated  columns,  which 
arise  from  the  anterior  angles  of  the  pons  Varolii,  and  enter  the  substance  of  the  cere- 
brum, after  a  course  of  about  six  lines. 

They  are  cylindrical,  and  in  contact  with  each  other  as  they  emerge  from  the  pons ; 
and  they  gradually  increase  in  size,  and  become  flattened  as  they  advance  forward,  up- 
ward, and  outward.    The  optic  tracts  (s  2,  fig.  272)  circumscribe  and  bound  them  in  front. 

Their  size  corresponds  to  that  of  the  cerebral  hemispheres.  They  are  of  equal  di- 
mensions in  a  well-formed  brain,  but  they  are  liable  to  become  atrophied  with  their  cor- 
responding hemisphere,  as  I  have  had  frequent  occasion  to  observe. 

Each  of  them  is  free  below,  and  on  its  outer  and  inner  side,  but  is  blended  above  with 
the  upper  portion  (A  ifg,  fig.  272)  of  the  isthmus  of  the  encephalon. 

Their  white  fasciculi  are  slightly  divergent,  and  are  often  intersected  at  right  angles 
by  certain  white  tracts,  some  of  which  emerge  from  the  testes  and  the  valve  of  Vieus- 
sens,  while  others  proceed  from  the  internal  surfaces  of  the  peduncles  themselves.  This 
arrangement  Gall  and  Spurzheim  have  named  the  transverse  interlacement  of  the  great 
fibrous  bundles  {see  fig.  272).  Owing  to  the  oblique  and  diverging  direction  of  the  cere- 
bral peduncles,  there  is  left  between  them  a  triangular  inter-peduncular  space  (between  r 
and  t,  fig.  276),  which  is  occupied  in  front  by  the  corpora  manmiillaria  or  albicantia  (z) 
and  the  tuber  cinereum  (v),  and  in  which  is  observed  behind  two  white  triangular  bun- 
dles, separated  from  the  peduncles  by  a  blackish  line.  We  shall  see  that  these  inter-pe- 
duncular bundles  are  merely  the  under  surface  of  the  bundles  of  re-enforcement  of  the 
medulla  oblongata,  or  the  "  faisceaux  innomines"  {I,  fig.  274). 

The  Superior  Peduncles  of  the  Cerebellum  and  the  Valve  of  Vieussens. 

The  superior  peduncles  of  the  cerebellum  (r,  figs.  271,  272, 280)  are  more  commonly  known 
as  the  processus  cerebelli  ad  testes,  a  name  given  to  them  by  Pourfour  Dupetit.  I  should 
observe,  however,  that  this  name  sanctions  an  anatomical  error  ;  for  the  superior  pedun- 
cles of  the  cerebellum  do  not  go  to  the  testes  at  all,  but  pass  under  them,  and  are  cover- 
ed by  the  corresponding  lateral  triangular  bundle  of  the  istlmius  ;  they  should  rather  be 
called  processus  cerebelli  ad  cerebrum  {Drelincourt.) 

The  inferior  peduncles  of  the  cerebellum  consist  of  two  lamellae,  which  arise  from  the 

*  Animals  which  have  no  lateral  lobe  of  the  cerebellum  have  no  pons  Varolii,  and  this  part  is  small  in  such 
as  have  very  small  lateral  cerebellar  lobes.  In  a  young-  girl  ten  years  of  age,  who  had  no  cerebellum,  I  fuund 
that  the  pons  was  also  wanting. 


fj^tf  NEUROLOGY. 

interior  of  the  cerebellum,  one  on  each  side  of  the  median  line,  pass  upward  and  forward 
parallel  to  each  other,  and  appear  to  be  continuous  with  the  testes. 

Their  upfer  convex  surface  is  covered  by  the  cerebellum  {see  fig.  280),  and  is  separated 
from  it  by  a  double  layer  of  the  pia  mater.  Their  inferior  surface  is  free,  and  assists  in 
forming  the  upper  wall  of  the  aqueduct  of  Sylvius.  Their  external  borders  are  each  sep- 
arated from  the  pons  by  a  furrow,  which  we  have  already  described  under  the  name  of 
lateral  furrow  of  the  isthmus.  Their  internal  borders  are  connected  together  by  means  of 
the  valve  of  Vieussens,  which  is  distinguished  by  its  colour  from  the  peduncles. 

Their  inferior  extremities  pass  deeply  into  the  central  white  substance  of  the  cerebellum. 

The  valve  of  Vieussens  {valvula  magna  cerebri,  I,  fig.  271  ;  v,  fig.  280  ;  g  to  w,  fig.  282) 
is  a  thin,  semi-transparent  lamina,  which  occupies  the  interval  between  the  two  superior 
peduncles  of  the  cerebellum  ;  it  is  the  velum  medullar e  or  velum  inter jectum  of  Haller. 

Its  posterior  surface  is  concave,  and  is  in  relation  above  with  the  superior  vermiform 
process  ;  in  its  lower  portion  it  adheres  to  the  transversely-notched  imperfect  lamella 
(linguetta  laminosa,  Malacarne),  in  which  the  superior  vermis  ends. 

The  median  line  of  this  posterior  surface  is  marked  by  a  line  {fig.  271),  which  Rolan- 
do considers  as  the  trace  of  the  line  of  junction  between  the  two  laminae,  of  which,  ac- 
cording to  him,  the  valve  consists. 

The  anterior  surface  is  convex,  and  forms  the  posterior  w^  of  the  aqueduct  of  Sylvius 
(leading  from  v  to  /,  fig.  282). 

The  borders  of  the  valve  ^xe  not  only  in  juxtaposition  with  the  corresponding  borders 
of  the  superior  peduncles  of  the  cerebellum,  but  appear  to  be  continuous  with  them. 

The  superior  extremity  is  narrow,  and  presents  a  transverse  band,  which  may  be  re- 
garded as  the  commissure  of  the  superior  peduncles  of  the  cerebellum  Euid  of  the  fourth 
pair  of  nerves. 

The  inferior  extremity  is  broad,  very  thin,  and  continuous  with  the  central  portion  ol 
the  median  lobe  of  the  cerebellum  (w). 

The  Tuber cula  Quadrigemina. 

Dissection. — Place  the  brain  with  its  base  upward,  turn  the  cerebellum  forward,  and 
remove  the  pia  mater. 

The  term  tubercula  quadrigemina  or  bigemina  (corpora  bigemina,  Soemmering,  optic  lobes 
of  the  lower  animals)  is  applied  to  four  tubercles  {fgfg,figs.  271,  272)  situated  regu- 
larly upon  the  upper  surface  of  the  isthmus,  two  on  each  side  of  the  median  line.  They 
form  two  pairs  :  the  anterior  or  superior  (/)  are  the  larger,  and  are  called  the  nates  (emi- 
nentia.  natiformes) ;  the  posterior  or  inferior  {g)  are  the  smaller,  and  are  called  the  testes 
{eminentia  testiformes). 

These  tubercles  are  placed  between  the  cerebrum  and  cerebellum,  and  are  situated 
above  the  peduncles  of  the  cerebrum,  and,  consequently,  upon  a  plane  anterior  to  that  of 
the  pons,  and  cannot  consistently  be  named  the  tubercles  of  the  mesocephalon,  as  was  done 
by  Chaussier.  The  anterior  part  of  the  aqueduct  of  Sylvius  passes  beneath  them  (.fg,fig- 
282),  and  establishes  a  communication  between  the  third  (l)  and  fourth  (v)  ventricles. 

They  are  comparatively  small,  indeed  merely  rudimentary  in  the  human  subject,  for 
their  development  in  the  animal  series  is  inversely  as  that  of  the  cerebrum  and  cerebel- 
lum.   The  space  which  they  occupy  is  a  parallelogram  of  ten  lines  by  eight. 

The  anterior  tubercles  are  always  larger  than  the  posterior  ;*  they  are  of  a  gray  col- 
our, oblong,  ellipsoid,  and  diverging ;  their  longest  diameter  is  directed  obliquely  forward 
and  outward.  The  posterior  tubercles  are  smaller,  and  more  detached ;  they  are  almost 
hemispherical,  and  of  a  white  colour  ;  but  not  so  white  as  the  fasciculated  medullary  sub- 
stance. 

A  furrow,  curved  like  a  parabola  opening  forward,  separates  the  anterior  from  the  pos- 
terior tubercles.  The  antero-posterior  furrow  along  the  median  line  separates  the  tu- 
bercles of  the  right  from  those  of  the  left  side.  From  this  furrow,  a  small,  grayish,  and 
tolerably  dense  cord  proceeds  backward,  and  descends  perpendicularly  upon  the  valve  of 
Vieussens,  or,  rather,  upon  the  transverse  commissure  by  which  it  is  surmounted,  and 
then  divides  into  two  or  three  branches.  This  cord  might  be  named  the  pillar  of  the 
valve  of  Vieussens  {columella  frenulum). 

The  lateral  triangular  bundle  {h,figs.  271,  272)  of  the  isthmus  terminates  in  the  poste- 
rior tubercle.  This  fasciculus,  which  was  pointed  out  by  Reil  ("  schleife,"  lemniscus, 
fillet),  Tiedemann,  and  Rolando,  who  described  it  as  arising  from  the  olivary  bodies,  pre- 
sents an  anterior  border,  which  is  directed  obliquely  forward  and  outward,  proceeds  along 
the  anterior  tubercle,  and  terminates  in  a  small  body  called  the  corpus  genicidatum  inter- 
num {i,  figs.  271,  272).  Its  posterior  border  inclines  downward,  backward,  and  outward, 
and  forms  a  slight  prominence  above  the  superior  peduncle  of  the  cerebellum,  which  is 
covered  by  it.  Its  base  corresponds  to  the  lateral  groove  of  the  isthmus,  which  separ- 
ates it  from  the  pons  and  the  peduncle  of  the  cerebrum.     Its  apex  extends  to  the  corre- 

*  The  relative  size  of  the  tuberculii  quadrigemina  varies  somewhat  in  different  animals.  The  anterior  tuber 
cles  are  much  larger  than  the  posterior  in  ruminants,  solipeds,  and  rodentia  ;  they  are  smaller  than  the  j>os- 
terior  in  camivora — in  the  dog,  for  example. 


INTERNAL  8TRUCTUEK  OP  THE  ISTHMUS  OP  THE  ENCEPHALON.  713 

sponding  posterior  tubercle  or  testis.  The  anterior  tubercles  or  nates  are  continuous 
with  the  optic  thalami  (a,  fig.  271),  being  separated  from  them  by  a  slight  depression. 
Some  white  fibres  proceed  from  the  anterior  extremity  of  these  tubercles,  and,  as  we 
shall  afterward  see,  form  a  thin  layer  above  the  corresponding  corpus  geniculatum  ex- 
ternum (;'),  and  assist  in  the  formation  of  the  optic  nerves.  These  white  bands  are  gen- 
erally proportioned  to  the  size  of  the  nates.* 

The  Internal  Structure  of  the  Isthmus  of  the  Encephalon. 

Dissection. — By  antero-posterior  and  transverse  sections  of  the  isthmus.  The  parts 
to  be  examined  by  laceration,  by  submitting  them  to  the  action  of  a  stream  of  water,  and 
also  after  they  have  been  hardened  in  alcohol,  or  by  being  boiled  in  oil,  or  a  solution  of  salt. 

The  internal  structure  of  the  isthmus  presents  three  very  distinct  strata  placed  one 
upon  the  other :  an  inferior,  formed  by  the  pons,  the  middle  peduncles  of  the  cerebellum, 
and  the  fasciculated  portion  of  the  peduncles  of  the  cerebrum  ;  a  middle  stratum,  form- 
ed by  the  prolongation  of  the  bundles  of  re-enforcement  of  the  medulla  oblongata  ;  and  a 
superior  stratum,  which  consists  of  the  triangular  lateral  bundles  of  the  isthmus,  the  su- 
perior peduncles  of  the  cerebellum,  the  valve  of  Vieussens,  and  the  tubercula  quadri- 
gemina. 

iTiternal  Structure  of  the  Pons  and  the  Peduncles  of  the  Cerebellum. 

It  has  been  stated  that  the  lower  surface  of  the  pons  presents  some  white  transverse 
fibres  (see  left  side,  fig.  273),  which  twist  g^  ^^^ 

upon  each  other  to  form  the  middle  pedun-  '^   ^^/ 

cles  of  the  cerebellum.  On  making  a  very 
superficial  incision  into  the  pons,  we  find, 
beneath  the  external  layer  of  white  matter, 
which  is  very  thin  behind,  and  a  little  thick- 
er in  front,  a  grayish-yellow  substance, 
which  is  traversed  by  the  transverse  fibres 
of  the  pons,  so  that  the  part  (m,  fig.  274) 
has  a  striated  appearance. 

If  the  handle  of  the  scalpel  be  passed  be- 
neath the  anterior  border  of  the  pons,  so  as 
to  remove  all  that  part  which  projects  be- 
yond the  level  of  the  peduncles  of  the  cere- 
brum, it  will  be  seen  that  the  pons  is  trav- 
ersed longitudinally  by  certain  white  bun- 
dles of  fibres  {b',  figs.  273,  274) ;  and  if,  moreover,  the  handle  of  the  scalpel  be  insinuated 
beneath  the  posterior  border  of  the  pons,  and  all  that  part  be  removed  which  projects  be- 
yond the  pyramidal  bodies  of  the  medulla  oblongata,  these  white  longitudinal  bundles 
which  traverse  the  pons  are  found  to  be  the  prolongation  of  the  pyramids  (i),  and  are 
themselves  continuous  with  the  peduncles  of  the  cerebrum  {n,fig.  282).  By  thus  separ- 
ating the  pons  into  very  thin  horizontal  layers,  it  will  be  found  that  the  longitudinal  {b') 
and  transverse  (m)  fibres  form  several  alternate  layers,  above  which  we  arrive  at  the 
middle  stratum  of  the  isthmus. 

The  peduncles  of  the  cerebrum  are  continuous  with  the  longitudinal  fibres  of  the  pons, 
and  the  middle  cerebellar  peduncles  with  the  transverse  fibres  of  the  same  part ;  the 
gray  matter  of  the  pons  extends  into  the  substance  of%he  latter,  and  gives  them  a  stria- 
ted appearance.  At  the  boundary  between  the  pons  and  the  middle  peduncles  of  the 
cerebellum  there  is  on  each  side  a  very  considerable  longitudinal  bundle,  which  forms 
the  origin  of  the  fifth  nerve,  and  which,  therefore,  does  not  belong  to  the  anterior  pyram- 
idal bodies.!  m 

The  absolute  continuity  of  the  anterior  pyramids  with  the  peduncles  of  the  cerebrum, 
through  the  pons,  may  be  regarded  as  a  type  of  the  structure  of  the  nervous  centre.  The 
two  sets  of  fibres  are  intermixed  in  the  pons,  so  as  to  intersect  each  other  at  right  an- 
gles, but  they  maintain  their  individuality,  t 

The  pons  presents  neither  a  raphe  nor  a  septum  in  the  median  line  :  the  fibres  of  the 
right  half  are  continuous  with  those  of  the  left.    The  white  fasciculated  fibres  {b')  of  the 

*  They  are  very  large  in  the  sheep  ;  it  appears  that  it  was  chiefly  from  the  anatomy  of  the  brain  in  this  an- 
imal that  Gall  founded  his  opinions  as  to  the  optic  nerves,  which  he  regards  as  arising  from  the  tubercula 
quadrigemina.     This  opinion  is  very  doubtful  as  far  as  concerns  the  human  subject. 

t  The  most  anterior  and  the  most  posterior  transverse  fibres  of  the  pons  have  a  very  peculiar  arrangement 
the  anterior  are  inflected  {o,fig.  282)  between  the  peduncles  of  the  cerebrum,  and  completely  occupy  the  in- 
terval between  them  ;  so  that  each  of  these  peduncles  is  embraced  by  a  distinct  ring,  formed  by  the  fibres  of 
the  pons  ;  and,  again,  the  most  posterior  fibres  of  the  pons  dip  between  the  anterior  pyramids,  each  of  which 
is  also  embraced  by  a  distinct  ring. 

t  The  continuity  of  the  pyramids  with  the  peduncles  of  the  cerebrum,  through  the  inferior  portion  of  the 
pons,  was  accurately  described  and  figured  by  Varolius  (Dc  Nervis  Opticis  nonnulksque  aliis,  1573),  by  Vieus- 
sens {NeuTographia  Universalis,  tab.  16),  by  Morgagni  {Adversaria  Anatomica,  v.),  and  by  Vicq  d'Azyr.  Vieus 
lens  showed  this  continuity  by  lacerating  the  pons.  Vicq  d'Azyr  showed  it  by  successively  removing  the  thin 
layers  of  the  pons  by  means  of  a  cutting  instrument.  The  plates  given  by  Gall  surpass  those  of  his  predeces- 
sors in  execution,  but  not  in  a  scieatific  point  of  view. 

4X 


'714  NEUROLOGY. 

peduncles  of  the  cerebrum,  which  are  continuous  with  the  anterior  pyramids  (A),  form 
part  of  the  inferior  stratum  of  the  isthmus  ;  these  fasciculated  fibres  are  parallel  and  per- 
fectly white,  without  any  intermixture  of  gray  matter. 

Internal  Structure  of  the  Middle  Stratum  of  the  Isthmus. 
When  the  pons,  or,  in  other  words,  the  successive  layers  of  the  inferior  portion  or 
etratmn  of  the  isthmus,  have  been  removed,  the  middle  stratum  is  exposed.     This  may 
Fiff.  274.  be  very  easily  displayed  in  a  brain  that  has  been 

well  hardened  in  alcohol.  It  is  then  seen  that  this 
middle  stratum  is  formed  by  a  prolongation  of  the 
fasciculi  of  re-enforcement  \faisceauxinnominis)  of 
the  medulla  oblongata,  which  becomes  enlarged  in 
passing  above  the  pons,  and  still  more  so  opposite 
the  peduncles  of  the  cerebrum,  above  which  we 
shall  trace  them  presently.  This  prolongation  {I, 
fig.  274)  then  passes  through  the  pons  at  right  an- 
gles. It  was  doubtless  to  illustrate  this  arrange- 
ment that  Varolius  described  the  medulla,  when 
viewed  from  below,  as  passing  beneath  the  pons 
like  the  water  of  a  canal  under  a  bridge.  This  re-enforcing  bundle,  pointed  out  by  Ro- 
lando {Recherches  sur  la  Moelle  Alongee,  1822)  under  the  appellation  of  the  middle  fasci- 
culus, has  been  correctly  represented  by  Mr.  Herbert  Mayo. 

Those  portions  (c,  fig.  269,  A)  of  the  bundles  of  re-enforcement  which  correspond  to 
the  peduncles  of  the  cerebrum  are  separated  from  the  superficial  part  of  the  peduncles 
themselves  (a)  by  a  layer  of  black  or  blackish  matter  (5) :  opposite  the  peduncles,  these 
two  bundles  are  intimately  united,*  but  they  soon  diverge  to  enter  the  optic  thalami. 
Are  they  simply  in  juxtaposition,  or  do  they  interlace  at  the  point  in  which  they  appear 
to  be  blended  1  I  am  inclined  to  believe  that  they  do  interlace  ;  but  I  have  not  yet  been 
able  to  demonstrate  this  clearly,  because  they  do  not  consist  of  very  distinct  bundles. 

The  Internal  Structure  of  the  Upper  Stratum  of  the  Isthmus. 

The  superior  peduncles  of  the  cerebellum  are  fasciculated  :  their  lower  extremities  {r,jig. 
274)  assist  in  forming  the  central  nucleus  of  the  cerebellum  ;  their  upper  extremities  (r') 
expand  into  a  great  number  of  fibres,  some  of  which  terminate  upon  the  anterior  wall 
of  the  fourth  ventricle,  on  each  side  of  the  median  line,  while  others  form  a  loop  below 
the  tubercula  quadrigemina. 

Structure  of  the  Tubercula  Quadrigemina. — Reil,  who  first  examined  the  structure  of 
the  tubercula  quadrigemina,  considers  them  as  consisting  of  four  rounded  masses  of 
gray  matter,  placed  upon  the  radiated  fibres  of  a  white  bundle,  which  spreads  out  beneath 
them.  This  white  bundle  (forming  part  of  the  bundle  h,  fig.  274),  which  he  calls  the  ^Z- 
let  or  loop,  is  derived  (c),  according  to  him,  partly  from  the  anterior  pyramidal,  and  part- 
ly from  the  olivary  body  (^d).  It  appears  to  me  to  be  nothing  more  than  the  above-men- 
tioned loop  formed  by  the  superior  peduncles  of  the  cerebellum,  below  the  tubercula 
quadrigemina. 

The  tubercula  quadrigemina  themselves  seem  to  me  to  be  rather  of  a  laminated  than 
of  a  fasciculated  structure.     Mayo  represents  them  as  having  a  fasciculated  texture. 

The  triangular  lateral  fasciculus  of  the  isthmus  (A,  fig.  272)  passes  in  one  direction  be 
tween  the  upper  and  middle  strata  of  the  isthmus,  and  in  another  it  may  be  traced  (form- 
ing the  other  part  of  the  bundle  h,  fig.  274)  downward  as  far  a^s  the  olivary  body.  The 
anterior  fibres  extend  from  the  testis  {g)  to  the  corpus  geniculatum  internum  (»),  pass 
beneath  that  body,  and  penetrate  into  the  interior  of  the  optic  thalamus.  This  triangu- 
lar fasciculus  forms  a  layer  upon  the  superior  peduncle  of  the  cerebellum,  from  which  it 
is  perfectly  distinct. 

Sections  of  the  Isthmus  of  the  EncephaJon. 

A  vertical  section  made  from  before  backward  through  the  median  line  of  the  istnmus 
will  give  an  excellent  view  of  its  three  portions  or  strata :  the  section  should  include  the 
medulla  oblongata  (see  fig.  274).  Upon  it  are  seen  the  white  and  gray  striated  mass 
(m  b'  m)  which  constitutes  the  pons,  the  re-enforcing  fasciculus  (/)  of  the  medulla  oblon- 
gata becoming  much  thicker  opposite  the  peduncles  of  the  cerebrum  than  in  the  pons. 

Transverse  vertical  sections  will  display  the  arrangement  of  the  pyramidal  bodies  and 
the  re-enforcing  fasciculi  as  they  pass  from  the  medulla  oblongata  into  the  isthmus.  In 
these  sections  a  thick  bundle  belonging  to  the  fifth  nerve  is  always  seen. 

Sections  of  the  tubercula  quadrigemina  show  that  they  are  neither  distinct  from  each 
other,  nor  from  the  external  and  internal  corpora  geniculata,  nor  from  the  re-enforcing 
fasciculi  of  the  medulla  oblongata  ;  but  that  these  latter  fasciculi  and  the  tubercula  qua- 
drigemina form  a  single  system,  surmounted  by  masses  of  nervous  matter,  which  are 
the  tubercles  themselves. 

*  IThey  here  constitute  the  so-called  integumentum  (c,fig.  269,  A) :  the  black  snbstance  is  called  the  locut 
tiger  (6),  and  the  suj^rficial  part  of  the  peduncle  is  named  the  crust  or  basis  (o).] 


THE   CEREBELLUM.  715 

Development  of  the  Isthmus  Encephah. 

The  development  of  the  pons  and  of  the  peduncles  of  the  cerebellum  is  in  relation 
with  that  of  the  cerebellum  ;  and  the  development  of  the  cerebral  peduncles  with  that  of 
the  cerebrum. 

In  the  embryo  of  two  months,  the  tubercula  quadrigemina  consist  merely  of  two  lam- 
inae, which  curve  upward  and  outward,  and  become  united  at  the  end  of  the  third  month. 

At  this  period  the  tubercula  quadrigemina  of  the  human  subject  are  in  the  same  con- 
dition as  those  of  the  lower  animals.  They  are  as  yet,  indeed,  only  two  in  number,  one 
on  each  side  of  the  middle  line  ;  and  they  are  hollow,  as  in  birds.  At  first  they  are  com- 
pletely exposed,  but  are  gradually  covered  by  the  hemispheres  of  the  cerebrum,  as  those 
parts  are  prolonged  backward. 

The  transverse  groove  which  divides  the  hitherto  single  pair  of  tubercles  into  an  an 
terior  and  a  posterior  tubercle  on  each  side  does  not  appear  until  about  the  sixth  month, 
at  which  time  the  cavity  in  their  interior  has  been  obliterated  by  the  thickening  of  their 
■parietes.* 

Comparative  Anatomy  of  the  Isthmus. 

The  pons  Varolii  and  middle  peduncles  of  the  cerebellum  exist  only  in  the  human  subject 
and  in  mammalia  generally ;  these  structures,  which  may  be  regarded  as  forming  the  com- 
missure of  the  cerebellum,  are  developed  exactly  in  proportion  to  the  size  of  the  lateral 
lobes  of  that  orgem ;  so  that  they  attain  their  utmost  development  in  the  human  subject, 
and  are  smallest  in  rodentia.  The  pons  and  cerebellar  peduncles  do  not  exist  in  the  re- 
maining three  classes  of  vertebrata  (birds,  reptiles,  and  fishes),  because  those  animals 
have  no  lateral  lobes  of  the  cerebellum. 

The  tubercula  quadrigemina  are  less  developed  in  man  than  in  the  lower  animals.  It 
may  even  be  said  that  the  development  of  these  tubercles  is  inversely  in  proportion  to 
that  of  the  lateral  lobes  of  the  cerebellum  and  the  hemispheres  of  the  cerebrum. 

The  anterior  tubercles  are  a  little  larger  than  the  posterior  in  the  human  subject :  in 
the  ruminants,  solipeds,  and  rodentia,  on  the  contrary,  the  anterior  tubercles  are  twice 
or  three  times  as  large  as  the  posterior.  In  the  carnivora  the  posterior  are  somewhat 
larger  than  the  anterior. 

They  are  covered  by  the  cerebrum  in  the  human  subject  and  the  highest  orders  of 
manomalia,  but  are  in  a  great  measure  exposed  in  the  rodentia  and  cheiroptera. 

In  birds,  reptiles,  and  fishes,  the  tubercles  are  only  two  in  number  (the  tubercula  bige- 
mina),  and  attain  their  maximum  development :  sometimes  they  are  even  larger  than 
the  cerebral  hemispheres  ;  they  are  hollow,  and  form  true  lobes,  which  are  called  the 
optic  lobes,  because,  in  fact,  the  optic  nerves  arise  exclusively  from  them. 

In  birds,  the  optic  lobes  are  situated  at  each  side  of  the  base  of  the  cerebrum.  The 
optic  lobes  of  birds  are  not  the  thalami  optici,  as  was  at  first  believed :  in  this  class  of 
animals  the  optic  thalami  are  thrown  forward. 

In  reptiles,  the  tubercula  quadrigemina  consist,  as  in  birds,  of  two  large,  ovoid,  and 
contiguous  lobes. 

In  fishes,  it  is  extremely  difficult  to  determine  what  are  the  tubercula  quadrigemina ; 
so  much  so,  indeed,  that  the  lobes  of  which  they  are  composed  have  been  taken  some- 
times for  the  cerebral  hemispheres,  and  sometimes  for  the  optic  thalami.  M.  Arsaky 
(De  Piscium  Cerebro)  has  successfully  refuted  both  of  these  errors. 


THE  CEREBELLUM. 


General  Description. — External  Characters  and  Conformation — Furrows,  Lobules,"  Lamina, 
and  Lamellce. — Internal  Conformation — the  Fourth  Ventricle,  its  Fibrous  Layers,  its  In- 
ferior Orifice,  and  its  Choroid  Plexus. — Sections  of  the  Cerebellum,  Vertical  and  Horizon- 
tal.— Examination  by  Means  of  Water,  and  of  the  Hardened  Cerebellum. — General  View 
of  the  Organ. — Development. — Comparative  Anatomy. 

The  cerebellum  {TrapEyKe<j>alic,  Aristotle,  1 1,  fig.  276  ;  h  h,  fig.  280),  or  little  brain,  is 
that  part  of  the  encephalon  which  occupies  the  right  and  left  inferior  occipital  fossae.  It 
exists  in  all  animals  which  have  a  cerebrum  and  spinal  cord,  and,  therefore,  in  all  the 
vertebrata. 

Cases  of  congenital  absence  of  the  cerebellum  are  extremely  rare.t 
Though  for  a  long  time  neglected,  the  anatomical  examination  of  the  cerebellum  was 
commenced  with  considerable  talent  by  Petit,  of  Namur  {Lcttre  d'un  Medecin  des  Hopi- 
tava  du  Roi,  Namur,  1710),  and  Malacarne  {Encephalotomia  nuova  Universale,  Torino, 
1780).  Vicq  d'Azyr  and  Chaussier  have  described  its  external  conformation  with  ex- 
traordinary accuracy ;  and  Reil,  Gall,  and  Rolando,  have  more  particularly  investigated 
its  structure. 

*  In  a  fetus  of  seven  months,  I  found  the  tubercula  qnadrig-emina  not  yet  divided  into  the  nates  and  testes, 
t  Vide  Anat.  Pathol.,  avec  fi^.,  for  a  case  of  absence  of  the  cerebellum. 


#f§  NEUROLOGY. 

The  External  Characters  and  Conformation  of  the  Cerebellutn. 

Situation. — The  cerebellum  is  enclosed  between  the  inferior  occipital  fossae  and  the 
process  of  the  dura  mater,  called  the  tentorium  cerebelli.  It  is  placed  {see  fig.  282)  at 
the  top  of  and  behind  the  spinal  cord,  and  the  isthmus  of  the  encephalon.  It  is  covered 
by  the  cerebrum  in  the  human  subject  only,  whence  the  name  cerebrum  inferius.  It  is 
posterior  to  the  brain  in  the  lower  animals,  and  is  therefore  called  cerebrum  posterius. 

The  dura  mater,  the  arachnoid,  and  the  pia  mater  form  a  threefold  investment  around 
it,  the  arrangement  of  which  has  been  already  described. 

Size  and  Weight. — The  cerebellum  is  larger  in  man  than  in  any  other  species.  It  has 
been  stated  by  Cuvier,  that  its  size  in  the  human  subject  is  so  exactly  proportioned  to 
that  of  the  brain,  that  correct  tables  may  be  formed  of  their  relative  weights ;  but  it  ap- 
pears to  me  that  facts  are  opposed  to  this  view. 

The  mean  weight  of  the  cerebellum,  including  the  pons  Varolii  and  medulla  oblongata, 
is  from  four  to  five  ounces  ;  the  proportion  between  the  cerebrum  and  cerebellum  may 
be  estimated  approximately  to  be  as  7  to  I.* 

According  to  Gall  and  Cuvier,  the  cerebellum  of  the  female  is  proportionally  larger 
than  that  of  the  male.  Gall  believes  that  its  size  is  in  a  direct  ratio  with  the  energy  of 
the  generative  function,  and  that  this  is  indicated  externally  by  the  relative  size  of  the 
inferior  occipital  protuberances.! 

The  cerebellum  is  proportionally  much  smaller  in  the  infant  than  in  the  adult ;  the 
relation  between  the  cerebrum  and  cerebellum  in  the  infant  is  as  20  to  1. 

Density. — The  consistence  of  the  cerebellum  has  been  much  studied  by  anatomists, 
who  are  far  from  being  agreed  upon  this  subject.  The  great  difficulty  depends  upon  the 
■want  of  accurate  means  of  estimating  its  consistence.  In  fact,  it  may  be  readily  con- 
ceived that  the  conversion  of  its  substance  into  a  pulp,  by  letting  weights  fall  upon  it 
from  a  determinate  height,  is  at  once  a  most  inconclusive  and  almost  inapplicable  meth- 
od of  ascertaining  the  point.  Another  source  of  difficulty  consists  in  the  fact  that  the 
cerebellum  is  not  homogeneous ;  so  that  results  obtained  in  reference  to  the  gray  matter 
do  not  apply  to  the  white  substance.  Out  of  fifty  cerebella  which  Malacarne  compared 
•with  the  corresponding  brains,  twenty-three  were  softer  than  the  brains  in  both  the  me- 
dullary and  cortical  substances  ;  in  thirteen  the  cortical  substance  was  equally  firm,  but 
the  medullary  substance  more  consistent  and  elastic  than  that  of  the  brain ;  ten  were 
more  dense  in  texture,  and  the  remaining  five  were  much  harder  than  the  corresponding 
brains.     In  some  cerebella  one  of  the  hemispheres  was  much  more  firm  than  the  other. 

The  results  of  my  observations  are,  that  the  medullary  centre  of  the  cerebellum  is  of 
a  firmer  consistence  than  that  of  the  cerebrum  ;  that  the  gray  substance  of  the  cerebel- 
lum is  softer  than  that  of  the  cerebrum;  and  that  the  gray  substance  of  the  former  be- 
comes softened  in  the  dead  body  with  such  extreme  rapidity,  that  it  is  difficult  to  meet 
with  a  cerebellum  in  which  this  substance  is  in  the  normal  state. 

Form. — The  general  outline  of  the  cerebellum  is  that  of  an  ellipsoid  flattened  from 
above  downward  ;  its  long  diameter  is  transverse,  and  measures  from  three  and  a  half 
to  four  inches  ;  its  antero-posterior  diameter  is  from  two  to  two  and  a  half  inches,  and 
its  vertical  diameter  two  inches  in  the  thickest  part,  and  about  six  lines  in  the  thinnest 
part,  that  is,  at  its  circumference.  The  figure  of  the  cerebellum  may  also  be  compared 
to  that  of  a  heart  on  playing  cards,  the  notch  of  which  is  directed  backward,  and  the 
truncated  apex  forward ;  or,  rather,  as  was  done  by  the  old  anatomists,  to  two  flattened 
spheroids,  united  together  at  their  points  of  contact. 

The  cerebellum  is  perfectly  symmetrical,  but  yet  a  marked  difference  between  the 
right  and  left  half  of  this  organ  is  not  unfrequently  observed.} 

The  cerebellum  presents  for  our  consideration  an  upper  and  a  lower  surface,  and  a 
circumference. 

The  upper  surface  {h  h,  fig.  280)  presents  along  the  median  line  an  antero-posterior  em- 
inence (d),  which  is  rather  prominent  in  front,  but  gradually  disappears  as  it  extends 
backward  :  it  is  named  the  superior  vermiform  process  {vermis  superior).  This  eminence, 
which  covers  the  valve  of  Vieussens  and  the  tubercula  quadrigemina,  should  be  regard- 
ed, as  Malacarne  states,  as  the  upper  part  of  the  median  lobe  of  the  cerebellum. 

On  each  side  {h  h)  the  upper  surface  of  the  cerebellum  forms  an  inclined  plane.  This 
surface  is  separated  from  the  posterior  lobe  of  the  cerebrum  by  the  tentorium  cerebelli. 

*  Chaassier  says,  "  In  a  considerable  number  of  comparative  experiments,  we  sometimes  found  that  the  adult 
cerebellum  was  -^th  or  ^th,  and  at  other  times,  but  rarely,  -pn  th  or  -ryth  the  weight  of  the  cerebrum.    In  the 

infant,  at  birth,  we  found  it  to  be  yV*-^'  tV*^'  PT*'''  "^V^''  ^'^i  ""'''  '"  °"®  '^*'^»  *^®"  3  S*^  '^^  ^"^'^^  weight 
of  the  brain." — {De  VEncephale,^.71.) 

+  In  my  opinion,  this  idea  can  only  be  regarded  as  an  ingenious  hypothesis.  The  aptitude  for  the  generative 
act  is  not  dependant  upon  the  cerebellum,  for  all  invertebrate  animals  are  destitute  of  this  organ  ;  and  in  cer- 
tain vertebrata,  where  the  generative  orgasm  is  quite  remarkable,  the  cerebellum  is  extremely  small.  Some 
observations,  however,  are  quoted,  which  appear  to  show  that  diminution  of  the  occipital  protuberance  ha» 
followed  extirpation  of  the  corresponding  testicle  :  but  it  must  first  be  proved  that  these  observations  are  cor 
red  ;  for  example,  that  the  inequality  of  the  occipital  protuberances  did  not  exist  previously  to  the  castration, 

t  In  four  cases  which  have  come  under  my  own  observation,  atrophy  of  the  right  hemisphere  of  the  cerebrum 
coexisted  with  atrophy  of  the  left  hemisphere  of  the  cerebellum  ;  I  am,  therefore,  led  to  conclude  that  there 
ve  certain  intimate  relations  between  the  opposite  hemispheres  of  these  two  portions  of  the  encephalon. 


THE  FURROWS,  LOBULES,  ETC.,  OF  THE  CEREBELLUM.      717 

The  lower  surface  of  the  cerebellum  {figs.  275,  276)  is  received  into  the  concavity  oi 
the  occipital  fossae,  to  which  it  is  exactly  fitted:  it  is  divided  into. two  rounded,  lateral 
halves  {h,  fig.  275),  the  lobes  of  the  cerebellum,  by  an  antero-posterior  fissure  (a  to  n), 
the  great  median  fissure  of  the  cerebellum  (vallecula,  Haller). 

The  back  part  of  the  cerebellum  is  completely  subdivided  by  this  fissure  {see  fig.  282), 
which  receives  the  falx  cerebelli ;  in  front,  the  fissure  opens  into  a  wide  furrow,  into 
which  the  medulla  oblongata  is  received  {see  fig.  276) ;  in  the  middle  of  the  fissure  is  a 
lozenge-shaped  interval,  at  the  bottom  of  which  is  seen  the  base  of  a  pyramidal  emi- 
nence {a  h  c,  fig.  275),  divided  transversely  pig.  275. 
into  rings  like  a  silkworm,  and  n£imed,  ac- 
cordingly, by  the  older  anatomists,  the  in- 
ferior vermiform  process  {vermis  inferior,  'pyr- 
amid, of  Malacarne).  This  eminence  is  de- 
veloped into  four  prolongations  or  branch- 
es, arranged  in  the  form  of  a  cross ;  the 
posterior  prolongation  (c)  is  tapering,  an(: 
occupies  the  back  part  of  the  great  median 
fissure  ;  the  two  lateral  processes  dip  (on 
each  side  of  h)  into  the  adjacent  portion  of 
the  fourth  ventricle  ;  and  the  anterior  (i) 
tapers  from  behind  forward,  and  terminates 
in  a  mammillary  enlargement  (a),  which  is 
free,  and  projects  into  the  fourth  ventricle.  It  has  been  unnecessarily  distinguished  from 
the  rest  of  the  inferior  vermiform  process  by  Malacarne  and  Chaussier,  under  the  name 
of  the  laminated  tubercle  of  the  fourth  ventricle  {tubercle  lamineux  du  quatrieme  ventricule).* 

The  inferior  vermiform  process  is  merely  the  lower  part  of  the  median  lobe  of  the  cere- 
bellum, of  which  the  superior  vermis  constitutes  the  upper  part.  The  superior  vermis  is 
continuous,  without  any  line  of  demarcation,  with  the  two  hemispheres  of  the  cerebel- 
lum, so  that  the  upper  part  of  that  organ  appears  undivided.  The  inferior  vermis,  which 
seems  at  first  sight  to  be  intended  to  separate  the  two  hemispheres,  nevertheless  forms 
the  means  of  connexion  between  them,  as  may  be  easily  seen  by  drawing  them  apart 
from  each  other. 

The  circumference  of  the  cerebellum  is  somewhat  elliptical,  or,  rather,  resembles  the 
heart  upon  playing  cards  ;  behind  and  in  the  middle  line  it  presents  a  notch  (n),  between 
the  convex  margins  of  which  a  triangular  interval  is  left,  into  which  the  falx  cerebelli 
and  the  internal  occipital  crest  are  received.  At  the  bottom  of  this  notch  the  surface 
of  the  cerebellum  is  transversely  grooved ;  this  part  unites  the  superior  to  the  inferior 
vermiform  process,  and  belongs  to  the  median  lobe  of  the  cerebellum. 

The  rounded  margins  of  the  7iotch  are  continuous  with  the  circumference  of  the  cere- 
bellum. In  front,  the  circumference  of  the  cerebellum  appears  to  be  formed  by  the  pons 
Varolii  {d,fig.  276)  and  middle  cerebellar  peduncles  (m),  which  are  in  relation  with  the 
posterior  surface  of  the  petrous  portion  of  the  temporal  bones,  and  are  therefore  straight, 
and  form  a  truncated  angle,  which  projects  forward,  and  corresponds  to  the  pons  Varolii. 

All  the  bundles  of  fibres  which  connect  the  cerebellum  with  the  cerebrum  and  spinsd 
cord  enter  at  the  anterior  part  of  its  circumference  :  thus,  besides  the  middle  peduncles 
of  the  cerebellum,  we  find  in  this  situation  its  superior  peduncles  (r,  fig.  272),  or  pro- 
cessus ad  testes,  and  its  inferior  peduncles  (cut  at  n),  or  processus  ad  medullam  oblongatam, 
to  which  we  shall  presently  return. 

The  Furrows,  Lobules,  Laminae,  and  Lamellce  of  the  Cerebellum. 

The  whole  surface  of  the  cerebellum  is  traversed  by  curved  lines  or  furrows,  which 
are,  for  the  most  part,  concentric  and  horizontal,  but  not  very  regular. 

These  furrows  are  not  parallel,  but  are  inflected  towards  each  other,  and  intersect  at 
very  acute  angles. 

They  may  be  divided  into  four  sets,  according  to  their  depth.  The  first  set  of  furrows 
are  the  deepest :  they  reach  as  far  as  the  central  nucleus,  and  divide  the  cerebellum  into 
segments  or  lobules  {g,  h,  I,  fig.  275).  omj 

These  segments  are  divided  into  secondary  segments  by  the  second  set  of  furrows. 

The  secondary  segments  are  again  subdivided  into  lamiruB  or  folia,  and  these  lamina 
into  lamella,  by  two  sets  of  yet  smaller  furrows. 

Pourfour  du  Petit,  Malacarne,  and  Chaussier  have  studied  the  sepnents,  laminae,  and 
lamellae  of  the  cerebellum  with  great  care,  and  have  even  counted  them.  The  differen- 
ces in  their  results!  are  not  so  much  a  proof  of  varieties  in  the  structure  of  the  organ 
as  of  the  want  of  some  uniform  method  of  enumeration. 

*  [The  inferior  vermiform  process  is  usually  described  as  consisting  of  three  portions  :  the  pyramid  (.c,fig. 
275),  the  uvula  (6),  and  the  nodulus  (o).] 

t  Winslow  admitted  3  lobules,  Collins  6,  Ponrfour  du  Petit  15,  Malacarne  11,  and  Chaussier  16.  Chaus- 
sier counted  60  laminae,  and  from  600  to  700  lamellae  ;  Malacarne  had  previously  counted  from  700  to  800  la- 
mellae. It  is  a  very  curious  fact  that  Malacarne  only  found  324  lamells  in  an  individual  labouring  under 
mental  alienation 


718  NEUROLOOV 

The  segments  which  occupy  the  circumference  of  the  organ  are  the  largest :  they  rep- 
resent segments  of  an  ellipsoid,  and  are  very  broad  in  the  middle,  and  narrowed  at  each 
extremity.  The  segments  of  the  upper  surface  are  concentric,  and  their  curvature  cor- 
responds to  that  of  the  entire  cerebellum.  The  segments  of  the  lower  surface  are  also 
concentric  in  each  half  or  lobe  of  the  cerebellum,  but  the  curves  of  one  side  are  inde- 
pendent of  those  of  the  other. 

The  laminae  or  folia  of  the  cerebellum  are  applied  to  each  other  like  the  leaves  of  a 
book ;  they  are  separated  from  each  other  in  their  whole  length,  and  are  attached  to  the 
rest  of  the  cerebellum  by  their  adherent  borders  only.  The  lamellae,  however,  are  ar- 
ranged in  a  different  manner,  for  they  pass  from  one  lamina  to  another,  and  even  from 
segment  to  segment.  In  fact,  if  the  segments  of  the  cerebellum  be  drawn  asunder,  the 
furrows  between  them  are  seen  to  be  traversed  obliquely  by  a  great  number  of  lamellae, 
which  extend  from  one  segment  to  another. 

The  arrangement  of  the  segments,  laminae,  and  lamellae  in  the  median  line  deserves 
particular  attention.  Opposite  the  superior  vermiform  process,  they  are  not  interrupted, 
but  are  merely  bent  slightly,  so  that  the  middle  portion  of  each  of  the  anterior  segments 
is,  as  it  were,  drawn  forward,  so  as  to  describe  a  curve,  having  its  concavity  turned 
backward.  Upon  this  surface  some  slight  peculiarities  are  observed  in  the  arrangement 
of  the  parts.  Along  the  median  line  there  seems,  indeed,  to  be  an  interchange  of  lam- 
inae and  lamellae,  some  of  each  of  which  become  thin,  and  end  in  points,  from  which  oth- 
ers appear  to  originate. 

Opposite  the  inferior  vermiform  process  the  two  hemispheres  of  the  cerebellum  are 
connected  together  by  means  of  the  latercd  prolongations  of  that  process.  But  in  front, 
i.  c,  opposite  the  medulla  oblongata,  the  two  hemispheres  of  the  cerebellum  are  perfect- 
ly distinct  from  each  other  (see  Jig.  275).  From  these  facts  we  may  estimate  to  what 
extent  the  comparison  is  correct  which  was  drawn  by  HaUer  between  the  superior  ver- 
miform process  and  the  corpus  callosum. 

At  the  back  part  of  the  cerebellum,  opposite  the  notch  in  that  situation,  the  two  hem- 
ispheres are  connected  by  means  of  certain  small  transverse  rings,  of  which  we  have 
already  spoken. 

The  superior  and  inferior  vermiform  processes  and  the  portion  situated  at  the  bottom 
of  the  notch  constitute  together  the  middle  lobe  of  the  cerebellum,  which  Gall  and  Spurz- 
heim  named  the  primitive  or  fundamental  part  of  the  cerebellum,  because  it  exists  in  all 
vertebrata,  and  because,  in  a  great  number  of  them  (as  in  birds,  reptiles,  and  fishes), 
where  the  lateral  lobes  of  this  organ  are  altogether  wanting,  it  constitutes  the  entire 
cerebellum.  It  is  well  to  add,  that  the  lateral  lobes  are  relatively  larger,  and  the  medi- 
an lobe  smaller  in  man  than  in  other  mammalia. 

A  rudimentary  median  lobe,  and  very  large  lateral  lobes,  are  the  characteristics  of  the 
human  cerebellum,  while  a  very  large  median  lobe,  and  rudimentary  lateral  lobes,  form 
the  characters  of  the  cerebellum  of  the  lower  animals. 

All  the  segments  of  the  cerebellum,  of  which  there  are  from  ten  to  twelve,  might  with 
propriety  be  distinguished  by  particular  names.  The  following  segments,  however,  re- 
quire special  mention :  the  segment  or  lobule  of  the  circumference  {I,  fig.  275),  which  is  the 
largest ;  the  lobules  of  the  medulla  oblongata  (lobuli  medullae  oblongatae),  which  are  situa- 
ted behind  that  part  (see  fig.  276),  are  concave  on  their  internal  surface,  which  is  accu- 
rately adapted  to  the  medulla,  and  convex  on  their  external  and  posterior  surface,  which 
dips  slightly  into  the  foramen  magnum.  These  lobules  (removed  from  f,fig.  275),  which 
have  been  noticed  by  all  qnatomists,  are  separated  from  one  another  by  the  inferior  vermi- 
form process  (the  uvula,  b),  and  each  of  them  terminates  in  front  and  on  the  inner  side  by  a 
mammillated  extremity  (called  the  amygdala  or  tonsil),  which  partially  fills  up  the  fourth 
ventricle.  The  other  inferior  segments  of  each  lobe  of  the  cerebellum  describe  concen- 
tric curves  around  this  segment.  The  lobule  of  the  pneumogastric  nerve  (rf)  is  a  sort  of 
prominent  tuft  (flocculus),  situated  (w,  fig.  276)  behind  the  pneumogastric  nerve  (8),  and 
below  the  facial  and  auditory  nerves  (7). 

The  Internal  Structure  of  the  Cerebellum. 
It  is  convenient  to  include  under  this  head  the  description  of  the  fourth  ventricle,  as 
well  as  that  of  the  substance  of  the  cerebellum. 

The  Fourth  Ventricle. 

Dissection. — Divide  the  median  lobe  of  the  cerebellum  vertically ;  make  a  vertical 
section  of  the  pons  along  the  median  line  ;  draw  asunder  the  medulla  oblongata  from 
the  cerebellum.  By  means  of  the  first  section  the  anterior  wall  of  the  fourth  ventricle  is 
exposed,  and  by  the  second  its  posterior  wall ;  by  drawing  apart  the  medulla  oblongata 
and  cerebellum,  the  ventricle  is  reached  by  its  inferior  extremity,  and  its  whole  depth 
can  be  seen.     It  is  important  to  examine  the  fourth  ventricle  in  all  its  aspects. 

The  fourth  ventricle  {c  to  y,  fig.  282)  is  that  rhomboidal  cavity  situated  between  the 
medulla  oblongata  and  isthmus  of  the  encephalon  (?  n),  which  forms  its  anterior  wall, 
and  the  cerebellum  (w),  which  constitutes  its  posterior  wall.    The  old  anatomists  follow- 


THE   FOURTH    VENTRICLE.  719 

ea  Galen  m  calling  it  the  ventricle  of  the  cerehellum.  Tiedemann  speaks  of  it  as  the  first 
ventricle,  because  it  is  developed  before  the  other  ventricles,  and  is  constant  in  all  mam- 
malia. 

The  fourth  ventricle  terminates  in  a  point  below,  expands  considerably  in  the  middle, 
and  is  again  contracted  at  its  upper  part,  where  it  becomes  continuous  with  the  third 
ventricle. 
.    We  shall  consider  separately  its  anterior  and  posterior  walls. 

The  anterior  or  inferior  wall  is  formed  by  the  posterior  surface  of  the  medulla  oblonga- 
gata  (see^.  271)  and  that  part  of  the  upper  surface  of  the  isthmus  of  the  encephalon 
which  corresponds  to  the  pons.  In  shape  it  resembles  a  lozenge  or  diamond,  truncated 
at  its  upper  point ;  the  upper  borders  of  the  lozenge  being  represented  by  the  superior 
peduncles  of  the  cerebellum  (r  to  g),  and  the  lower  by  the  restiform  bodies  (e)  :  the  poste- 
rior surface  of  the  re-enforcing  fasciculi  {faisceaux  innomines)  of  the  medulla  oblongata 
constitutes  this  anterior  wall,  which  is  lined  by  a  dense  and  easily  separable  membrane. 

The  'posterior  or  superior  wall  represents  a  vaulted  roof,  which  is  formed  above  by  the 
superior  peduncles  of  the  cerebellum  (r  to  g)  and  the  valve  of  Vieussens  {l,  fig.  271 ;  I, 
fig,  275 ;  g  w,  fig.  282),  lower  down  by  the  cerebellum  (w),  and  below  by  a  fibrous  mem- 
brane, continuous  with  the  neurilemma  of  the  spinal  cord. 

Opposite  the  middle,  i.  e.,  the  broadest  part  of  this  posterior  wall  (see_^.  275),  are  sit- 
uated three  mammillary  projections — one  median  and  two  lateral :  the  first  (b,  the  uatu- 
la)  is  the  anterior  segment  of  the  median  lobe  of  the  cerebellum ;  the  other  two  (the 
amygdcdae)  are  formed  by  the  innermost  laminae  of  the  lobule  of  the  medulla  oblongata 
(cut  away  at/).  These  latter  are  not  bathed  in  the  fluid  of  the  ventricle,  but  are  sep- 
arated from  it  by  the  fibrous  membrane  lining  that  cavity. 

The  median  mammillary  projection  (6),  named  by  Malacarne  and  Chaussier  the  lami- 
nated tubercle  of  the  fourth  ventricle,  resembles  a  movable  valve.  It  is  attached  to  the 
cerebellum  by  two  white  pedicles,  which  pass  outward  and  backward  upon  the  lateral 
processes  of  the  crucial  eminence  formed  by  the  inferior  vermis.  Connected  to  its  an- 
terior extremity  (the  nodulus,  a)  are  seen  two  broad  folds  {semilunar  folds,  e),  which  arise 
from  it,  one  on  each  side,  and  become  continuous  with  the  roots  of  the  corresponding 
sub-peduncular  lobules  or  flocculi  {d). 

These  folds,  which  are  quite  distinct  from  the  valvulse  Tarini,  are  extremely  thin  and 
semi-transparent ;  their  convex  borders  adhere  to  the  back  part  of  the  fourth  ventricle  ; 
the  concave  margins  and  their  two  surfaces  are  free.*  The  two  semilunar  folds  and 
the  intermediate  projection,  or  the  nodule,  may  be  compared  to  the  soft  palate,  the  mam- 
millary projection  representing  the  uvula,  t 

Opposite  the  upper  angle  of  its  rhomboidal  cavity,  the  fourth  ventricle  {v,  fig.  282)  be- 
comes continuous  with  the  third  (Z),  through  a  canal,  named  iter  a  tertio  ad  quartum  ven- 
triculum,  or  the  aqueduct  of  Sylvius,  which,  however,  had  been  described  by  Galen  :  this 
aqueduct  is  formed  beneath  the  tubercula  quadrigemina  {f  g)  and  the  valve  of.Vieus- 
sens  {g  w). 

The  lateral  angles  of  the  fourth  ventricle  are  much  elongated,  and  reach  as  far  as  op- 
posite the  inner  extremity  of  the  corpus  dentatum  of  the  cerebellum. 

At  the  inferior  angle  (y)  of  the  fourth  ventricle  is  situated  a  fibrous  layer,  which  con- 
stitutes its  floor,  and  also  an  orifice  of  communication  between  the  ventricle  and  the 
sub-arachnoid  space. 

The  Fibrous  Layers  of  the  Fourth  Ventricle. 

Floor  of  the  Fourth  Ventricle. — On  carefully  drawing  the  medulla  oblongata  away  from 
the  cerebellum,  a  fibrous  layer  is  seen  extending  from  one  to  the  other,  and  forming,  as 
it  were,  the  floor  of  the  fourth  ventricle.  This  layer,  which  is  continuous  with  the  neu- 
rilemma of  the  medulla  oblongata,  consists  of  three  very  distinct  parts  :  of  a  median 
portion,  shaped  like  a  triangular  tongue,  which  passes  horizontally  backward,  and  is  ap- 
pUed  to  the  anterior  extremity  of  the  inferior  vermis,  to  which  it  adheres  ;  and  of  two 
triangular  lateral  portions,  which  form  the  sides  of  the  orifice  of  the  fourth  ventricle,  and 
which  were  described  by  Tarin  as  the  valves  of  the  base  of  the  fourth  ventricle. 

Besides  this  fibrous  layer,  there  is  another  on  each  side,  situated  behind  the  roots  of 
the  pneumogastric  nerve  :  these  layers  adhere  to  those  roots,  and  we  shall  therefore 
name  them  the  fibrous  layers  of  the  pneumogastric  nerves ;  they  close  the  fourth  ventricle 
upon  the  sides  of  the  medulla  oblongata,  and  when  they  are  removed  the  ventricle  is 
quite  open.  They  extend  from  the  restiform  bodies  to  the  lobules  of  the  pneumogastric 
nerves,  and  are  prolonged  upward  upon  the  auditory  nerves. 

The  Inferior  Orifice  of  the  Fourth  Ventricle. 
If  the  medulla  oblongata  and  cerebellum  be  drawn  apart,  there  is  seen  in  the  median 

*  [These  two  folds  constitute  the  posterior  medullary  velum  of  the  cerebellum,  the  valve  of  Vieussens  form- 
ing the  anterior  velum.] 

t  [The  terms  uvv.la  and  amygdalie,  or  tonsils,  have,  as  already  noticed,  been  applied  to  another  series  ot 
three  bodies  which  are  arranged  behind  the  nodule,  the  flocculi  and  the  posterior  vela,  and  consist  of  the  lam- 
inated tubercle  of  the  fourth  ventricle,  and  of  the  inner  portions  of  the  lobes  of  the  medulla  oblongata  (see  p. 
718).]  •  s{  vj'  »»i»<»««>n»^-"iTiv  r-  -  -■ 


71^  NEUROLOGY. 

line,  between  the  inferior  cerebellar  arteries,  a  lozenge-shaped  opening  (at  y,  fig.  282), 
bounded,  in  front,  by  the  base  of  the  calamus  scriptorius  ;  behind,  by  the  anterior  pro- 
longation of  the  inferior  vermiform  process,  which  is  covered  by  the  median  tongue  of 
the  fibrous  layer  ;  and  upon  the  sides,  in  front,  by  the  ragged  edges  of  the  lateral  por- 
tions of  the  fibrous  layer,  and  by  the  internal  surfaces  of  the  lobules  of  the  medulla  ob- 
longata. 

This  opening  was  pointed  out  by  M.  Magendie  as  establishing  a  communication  be- 
tween the  general  ventricular  cavity  and  the  sub-arachnoid  space.  It  has  been  asked, 
Is  it  a  natural  opening,  or  is  it  produced  accidentally  by  the  very  means  employed  in  its 
demonstration  1     The  following  are  the  arguments  on  both  sides  of  the  question  : 

In  opposition  to  the  existence  of  an  opening  in  this  situation,  it  is  urged  that  the  mar- 
gin of  the  orifice  has  none  of  the  characters  of  that  of  a  natural  opening,  the  edges  of 
which  are  generally  smooth  and  rounded ;  but  in  this  orifice  they  are  lacerated,  and  there 
is  almost  always  some  membranous  shreds  at  the  point  of  the  calamus  scriptorius.  If 
the  median  triangular  tongue  of  the  fibrous  layer,  which  is  applied  to  the  inferior  vermis, 
be  detached,  it  is  seen  to  be  merely  a  flap  of  that  membrane,  the  size  of  which  exactly 
corresponds  to  that  of  the  opening,  so  as  to  close  it  completely.  This  point  may  be  ren- 
dered still  more  evident  by  tracing  the  membrane  from  before  backward,  after  having  di- 
vided the  pons  and  medulla  oblongata. 

Again,  the  fibrous  layer,  which  forms  the  floor  of  the  fourth  ventricle,  is  entire  in  the 
dog  and  sheep ;  I  have  found  it  in  the  same  condition  five  or  six  times  in  the  human 
subject ;  and  if  it  be  objected  that,  in  this  case,  there  might  have  been  an  accidental  ob- 
literation of  the  opening,  I  could  answer  that  there  was  no  trace  of  disease,  either  in  the 
cerebro-spinal  axis,  or  in  the  membranes. 

I  may  also  mention  that,  in  several  cases  of  chronic  hydrocephalus,  several  pounds  ol 
fluid  were  found  in  the  ventricles,  and  none  whatever  in  the  sub-arachnoid  space. 

Lastly,  in  the  brains  of  several  infants,  who  had  died  with  all  the  symptoms  of  acute 
ventricular  hydrocephalus,  I  have  found  the  lateral  ventricles  very  large,  but  empty  ;  and 
in  these  cases,  it  has  occurred  to  me  that  the  fibrous  layer  might  have  been  perforated 
opposite  the  inferior  angle  of  the  fourth  ventricle,  and  have  thus  allowed  the  fluid  to 
escape,  which,  in  the  greater  number  of  cases,  is  retained  by  this  layer  within  the  ven- 
tricular cavity. 

Such  are  the  facts  which  appear  to  me  to  militate  against  the  idea  of  the  existence  of 
an  opening  in  the  floor  of  the  fourth  ventricle  ;  but,  on  the  other  hand,  if  we  consider 
that,  in  an  immense  majority  of  instances,  whatever  care  may  be  taken  in  removing  the 
brain  from  the  cranium,  we  always  find  this  opening  both  in  the  foetus  and  in  the  adult ; 
that  in  apoplectic  effusions  into  the  ventricles,  we  always  find  some  bloody  serum  in  the 
sub-arachnoid  space  ;  and  that  if  a  coloured  fluid  be  injected  into  the  ventricles  of  the 
cerebrum,  or  into  the  sub-arachnoid  space  around  the  cord,  it  will  in  either  case  pass 
freely  /rom  one  into  the  other,  we  shall  be  led  to  conclude  that  there  is  a  regular  com- 
munication between  the  cavity  of  the  ventricles  and  the  sub-arachnoid  space,  and  that 
the  orifice  just  described  is  the  channel  of  communication  between  them.* 

The  Choroid  Plexuses  of  the  Fourth  Ventricle. 

The  choroid  ■plexuses  of  the  fourth  ventricle  are  two  in  number ;  they  commence  one  on 
each  side,  by  a  very  slender  extremity,  upon  the  anterior  surface  of  the  sort  of  fibrous 
tongue  which  is  attached  to  the  inferior  vermis  ;  from  this  point  they  pass  in  a  diver- 
ging course  upward,  are  then  inclined  outward,  turn  round  the  sides  of  the  median  emi- 
nence of  the  fourth  ventricle,  pass  horizontally  outward  behind  the  restiform  bodies,  and 
then  behind  the  fibrous  layer  of  the  corresponding  pneumogastric  nerve,  where  they  be- 
come considerably  enlarged,  and  at  length  terminate  upon  the  sub-peduncular  lobes. 

The  inner  surface  of  the  fourth  ventricle  is  smooth,  in  consequence  of  being  lined  by 
a  membrane  resembling  a  serous  membrane,  which  is  much  stronger  over  the  posterior 
surface  of  the  medulla  oblongata  than  at  any  other  point. 

Sections  of  the  Cerebellum. 

On  cutting  through  the  cerebellum,  it  is  found  to  be  composed  (see  figs.  273,  274)  of 
two  substances,  an  external  cortical  or  gray  substance,  and  a  central  or  medullary  substance, 
which  is  white ;  the  gray  substance  is  soft,  and  is  almost  always  torn  off  with  the  mem- 
branes, however  slightly  the  cerebellum  may  be  altered  by  decomposition.  The  white 
substance  is  compact,  and  resists  a  tolerably  firm  pressure.! 

Between  the  gray  and  white  substances  there  is  seen,  upon  a  section  of  the  cerebellum, 
a  narrow  yellowish  band  or  streak,  which  depends  on  the  existence  of  a  layer  of  a  yellow 
substance,  of  much  greater  firmness  than  the  gray  matter,  and  strongly  adherent  to  the 
white  substance.  By  laceration  the  gray  matter  is  destroyed,  and  this  yellow  layer  is 
exposed.    There  are,  therefore,  three  substances  in  the  cerebellum :  the  gray,  the  yellow, 

'  See  note  on  the  sub- arachnoid  space  (p.  690). 

t  For  an  account  of  the  minute  structure  of  these  substances,  see  note,  p.  701. 


SECTIONS   OF    THE    CEREBELLUM.  781 

and  the  white.  I  would  compare  the  yellow  layer  of  the  cerebellum  to  the  yellow  folded 
membrane  of  the  olivary  bodies.* 

A  question  liere  arises,  What  is  the  proportion  between  the  gray  and  the  white  mat- 
ter ?  The  most  superficial  examination  of  the  cerebellum  will  show  that  the  gray  mat- 
ter predominates ;  and  this  can  be  clearly  demonstrated  by  macerating  the  cerebellum 
for  several  days.  The  gray  matter,  which  is  more  easily  decomposed,  becomes  con- 
verted into  a  pulp,  and  the  remaining  nucleus  of  white  substance  scarcely  represents  a 
third,  eitlier  of  the  weight  or  bulk  of  the  cerebellum. 

We  shall  now  proceed  to  describe  the  appearance  of  vertical  and  horizontal  sections 
of  the  cerebellum. 

Vertical  Sections. 

Upon  longitudinal  vertical  sections  of  the  cerebellum,  the  gray  and  white  substances 
present  a  very  elegant  arrangement,  known  by  the  picturesque  name  of  the  arbor  vita ; 
a  title  derived  either  from  the  importance  which  has  been  attached  to  this  structure,  or 
from  its  resemblance  in  figure  to  the  foliage  of  the  tree  so  called.  Upon  a  section  maule 
through  the  median  line,  the  arbor  vita  of  the  middle  lobe  {w,  fig.  282)  is  seen  ;  and  upon 
one  made  on  either  side,  the  arhor  vita  of  the  lateral  lobes. 

The  arbor  vita  of  the  median  lobe  consists  of  a  central  nucleus  of  white  substance,  of  a 
triangular  form,  from  which  two  principal  branches  proceed  :  one  inferior,  which  is  dis- 
tributed to  the  whole  of  the  inferior  vermis  and  the  back  part  of  the  median  lobe  ;  the 
'  other  superior,  which  passes  into  the  whole  of  the  superior  vermis.  These  two  branches 
subdivide  into  six  others,  which  vary  in  direction,  length,  and  thickness,  and  are  them- 
selves subdivided  into  still  smaller  branches,  and  these,  again,  into  the  smallest  ramifica- 
tions. A  slight  enlargement  of  the  white  substance  is  always  observed  opposite  the 
points  of  division. 

A  very  thin  yellowish  layer,  and  outside  this  a  layer  of  gray  matter,  about  a  line  in 
thickness,  covers  each  of  the  ramifications  of  the  white  substance,  and  thus  forms  the 
lamellie,  laminae,  and  segments  of  the  median  lobe. 

This  section  enables  us  to  prove  the  existence  of  the  middle  lobe  of  the  cerebellum 
and  the  continuity  of  the  superior  and  inferior  vermis  ;  it  also  shows  the  general  form 
of  the  middle  lobe,  which  is  rotate  or  wheel-shaped  (the  anterior  extremity  of  the  in- 
ferior vermis,  i.  e.,  the  nodule,  comes  into  contact  with  the  valve  of  Vieussens) ;  the 
number  and  arrangement  of  the  segments,  laminae,  and  lamellae  of  the  cerebellum;  and, 
lastly,  the  nature  of  the  valve  of  Vieussens,  which  is  nothing  more  than  the  uppermost 
subdivision  of  the  central  nucleus,  and  may  be  regarded  as  one  half  of  a  lamella  of  the 
cerebellum. 

The  Arbor  Vita  of  the  Lateral  Lobes. — A  vertical  section  from  the  middle  peduncles  of 
the  cerebellum  towards  the  circumference  displays  the  arbor  vitae  of  the  lateral  lobes. 

In  the  centre  of  each  lobe  is  seen  a  white  central  nucleus,  from  which  fifteen  or  six- 
teen principal  branches  are  given  off,  to  form  the  nuclei  of  a  corresponding  number  of 
the  segments.  These  branches  are  subdivided  into  secondary  branches,  and  those  into 
the  ultimate  ramifications.  A  yellowish  layer  covers  each  of  these  successive  divisions, 
and  upon  that  a  gray  layer,  about  a  line  in  thickness,  is  accurately  moulded. 

Upon  sections  of  this  kind  it  is  easily  seen  that  the  segments  of  the  cerebellum  are 
very  unequal  in  size,  in  direction,  and  in  their  manner  of  division ;  that  the  superior 
segments  are  the  smallest,  the  segments  of  the  circumference  the  largest,!  and  the  in- 
ferior segments  of  an  intermediate  size  ;  that  there  is  no  vacant  space  between  the  seg- 
ments, but  that  both  laminae  and  lamellae  occupy  the  intervals ;  and,  lastly,  that  all  of 
these  segments  curve  forward  upon  themselves,  so  as  to  form  a  series  of  horizontal 
wheels  or  circles,  the  plane  of  which  is  at  right  angles  to  that  of  the  wheel-shaped 
mass  of  the  middle  lobe. 

In  the  centre  of  the  white  nucleus  of  each  half  of  the  cerebellum  is  the  corpus  rhom- 
boideum,  or  corpus  dentalum :%  these  bodies  are  of  an  ovoid  form ;  their  yellowish  invest- 
ing layer  is  dense,  and  folded  backward  and  forward  upon  itself,  and  exactly  resembles 
that  of  the  olivary  bodies ;  and  I  have  been  accustomed  to  speak  of  these  bodies  as  the 
olivary  bodies  of  the  cerebellum.  Gall  and  Spurzheim  regarded  them  as  ganglions  of 
re-enforcement,  and  called  them  tlie  ganglions  of  the  cerebellum.  Their  shortest  or  verti- 
cal diameter  is  about  one  third  of  their  long  or  horizontal  diameter ;  in  one  case,  where 
the  latter  was  fifteen  lines,  the  former  was  five  lines  :  moreover,  the  size  of  the  corpora 
dentata  of  the  cerebellum  varies  in  different  subjects,  and  is  in  proportion  to  the  size  of 

*  Rolando  ( Ossemazioni  suV  Cervetetto,  p.  187,  1823)  appears  to  me  to  have  been  the  first  to  establish  the  fact 
of  the  existence  of  three  substances  :  the  medoHare,  the  cinereo  rossigna,  and  the  cinerea  esterna  e  corticate. 

t  The  segment  of  the  circumference,  which  is  the  largest  of  all,  immediately  divides  into  two  smaller  seg- 
ments ;  it  has  liecu  iucorrecUy  stated  that  there  is  a  horizontal  fissure  along  the  circumference  of  the  cere- 
bellum, extending  from  one  of  the  middle  peduncles  to  the  other. 

t  In  order  to  divide  the  corpus  dentatum,  the  section  must  be  made  opposite  the  corresponding  inferior  pe- 
duncle (if  the  cerebellum.  I  would  recommend  that  one  section  be  made  to  extend  through  the  corpus  denta- 
lum of  the  cerebellum,  and  also  through  the  olivary  body,  so  that  some  idea  may  be  formed  of  the  analogy  be- 
tween these  two  |>arts. 

4Y 


NEUROLOGY. 

the  lateral  lobes  of  that  organ :  they  are,  therefore,  much  less  developed  in  the  lower 
animals  than  in  man. 

The  peduncles  of  the  cerebellum  are  six  in  number,  three  on  each  side,  namely,  a  supe- 
rior, a  middle,  and  an  inferior ;  they  all  originate,  or,  it  may  be  said,  terminate  in  the  cen- 
tral nucleus. 

The  superior  peduncles  of  the  cerebellum  are  generally  known  as  the  processus  cerebelli 
ad  testes ;  ttiey  are  seen  (r,  fg.  280)  in  front  of  the  superior  vermiform  process,  and  seem 
to  pass  up  to  the  tubercula  quadrigemina.  We  shall  afterward  see  that  this  is  only  ap- 
parent. 

The  inferior  peduncles  (processus  cerebelli  ad  medullam  oblongatam)  are,  in  fact,  the  resti- 
form  bodies  ;  they  establish  a  direct  and  intimate  communication  between  the  cerebel- 
lirni  and  the  spinal  cord. 

Lastly,  the  middle  peduncles  {m,  fig.  276),  which  are  anterior  to  the  two  preceding  sets, 
occupy  the  fore  part  of  the  circumference  of  the  cerebellum,  and  are  continued  into  the 
pons  Varolii  without  any  line  of  demarcation.  They  are  called  also  the  cerebellar  pedun- 
dea  {processus  cerebelli  ad  potitem),  and  the  crura  or  legs  of  the  medulla  oblongata. 

Horizontal  Sections. 

Horizontal  sections  of  the  cerebellum  have  been  studied  with  very  great  care,  and  have 
been  well  figured  by  Vicq  d'Azyr ;  they  show  that  the  dimensions  of  the  central  nucleus 
are  much  greater  in  the  horizontal  than  in  the  vertical  direction.* 

Upon  these  sections,  which  should  be  made  parallel  to  the  upper  surface  of  the  cere- 
bellum, is  seen  the  relative  disposition  of  the  laminae,  which  are  sometimes  parallel  and 
sometimes  oblique  in  reference  to  each  other,  and  which  either  extend  around  the  entire 
circumference  of  the  organ,  or  terminate  in  tapering  extremities  and  again  commence, 
and  pass  from  one  segment  to  another. 

Lastly,  these  horizontal  sections  show  the  continuity  of  the  right  and  left  lobes  of  the 
cerebellum  by  means  of  the  middle  lobe.  In  this  middle  lobe  the  lamellae  are  more  ir- 
regular than  in  the  lateral  lobes  ;  they  intersect  each  other  at  various  angles,  and  be- 
come again  united  into  new  combinations,  so  that  several  anatomists  have  admitted  the 
existence  of  a  true  decussation  in  this  middle  portion  of  the  cerebellum. 

The  middle  lobe  also  has  its  medullary  centre,  which  connects  the  lateral  medullary 
centre  in  such  a  manner  that,  by  a  successful  section,  a  sort  of  cerebellar  centrum  ovale 
is  obtained,  analogous  to  the  centrum  ovale  of  Vieussens  in  the  cerebrum. 

Examination  of  the  Cerebellum  by  means  of  a  Stream  of  Water,  and  Dissec- 
tion of  the  Hardened  Cerebellum. 
A  stream  of  water  directed  upon  vertical  sections  of  the  cerebellum  decomposes  the 
white  nucleus  of  each  lateral  lobe  into  a  great  number  of  extremely  thin  leaves,  which 
constitute  the  different  laminae  or  lamellae  of  the  cerebellum.  All  these  laminae  and  la- 
mellae terminate  in  the  central  nucleus  of  the  corresponding  lobe.  Each  lamella  is  fan- 
shaped,  its  adherent  border  being  very  narrow,  concave,  and  applied  io  the  central  nu- 
cleus, with  which  it  is  evidently  continuous,  while  its  convex  margin  corresponds  to  the 
surface  of  the  cerebellum.  The  arrangement  of  these  lamellae  is  very  beautiful  and  cu- 
rious :  some  of  them  ascend  to  form  the  segments,  lamina,  and  lamellae  of  the  upper 
surface  of  the  cerebellum ;  others  descend  to  form  the  corresponding  parts  of  the  lower 
surface,  and  the  intermediate  ones  pass  horizontally  to  the  circumference,  and  are  dis- 
posed in  a  similar  manner.  Opposite  each  point  of  subdivision  there  seems  to  be  an  en- 
largement of  the  white  substance,  but  this  depends  not  upon  an  actual  increase  of  that 
substance,  but  upon  the  divergence  of  the  lamellae. 

The  structure  of  the  cerebellum,  therefore,  considered  generally,  is  laminated.  From 
the  central  white  nucleus  proceed  innumerable  lamina;,  which,  though  in  juxtaposition, 
are  never  blended  together,  and  which  form  groups,  that  are  themselves  subdivided  again 
and  again,  like  the  branches  of  a  tree,  the  ultimate  lamella  always  containing  at  least 
two  leaflets.  Can  anatomy  teach  us  anything  beyond  this  laminated  arrangement  1  In 
each  lamella  certain  radiated  striae  are  seen  ;  and  it  may  be  asked.  Whether  these  prove 
the  existence  of  a  linear  or  fibrous  structure  1  It  is  certainly  true  that  the  lamellae  may 
be  divided  in  the  direction  of  these  striae,  but  it  is  far  from  being  evident  that  they  con- 
sist of  linear  fibres. 

In  the  central  nucleus,  the  laminae,  being  more  firmly  pressed  together,  are  separated 
by  the  stream  of  water  with  greater  difiiculty  than  the  laminae  near  the  surface  :  the 
corpora  dentata  of  the  cerebellum  are  peculiarly  firm.  The  stream  of  water  insinuates 
itself  into  these  bodies  opposite  their  internal  extremity,  which  appears  to  be  naturally 
open,  and  divides  them  into  two  halves,  a  superior  and  an  inferior.  It  is  then  seen  that 
the  dentated  appearance  of  their  section  results  from  the  reduplication  of  the  dense  yel- 
lowish layer  in  which  they  are  enclosed  ;  also,  that  the  white  substance  penetrates  into 
the  interior  of  these  bodies  at  their  internal  surface,  accompanied  by  a  great  number  of 

*  In  each  lobe  of  the  cerebellum  there  is  a  medullary  centre,  that  is,  a  spot  in  which  the  section  of  the  whit* 
substance  is  larger  than  at  other  points. 


GENERAL    VIEW    OF    THE    CEREBELLUM.  723 

vessels ;  and  that  this  white  substance  is  arranged  in  lamellae,  which  terminate  at  three 
different  points  of  the  yellowish  layer,  so  that  each  of  the  corpora  dentata  resembles  a 
small  cerebellum. 

Examination  of  the  Hardened  Cerebellum. — The  examination  of  the  cerebellum,  when 
hardened  by  alcohol,  or  by  boiling  in  oil,  or  salt  and  water,  or  by  maceration  in  a  solu- 
tion of  salt  and  bichloride  of  mercury,  of  the  strength  recommended  by  Rolando,  confirms 
all  the  results  which  have  been  obtained  by  the  preceding  method  of  investigation. 

These  modes  of  preparation,  moreover,  enable  us  to  examine  more  completely  than  in 
any  other  way  the  relations  of  the  central  nuclei  of  the  lobes  to  the  peduncles  of  the  cere- 
bellum. It  is  seen  most  distinctly  that  these  peduncles  (m  n.  Jig.  273 ;  n  r,  fig.  274) 
emerge  from  or  terminate  in  the  central  nuclei  ( p  p),  but  it  is  very  difficult  to  ascertain 
their  precise  arrangement  within  the  nuclei.  All  that  we  know  is  the  fact  that,  as  soon 
as  they  emerge  from  the  central  nuclei,  they  assume  a  fasciculated  character,  and  that 
all  the  lamellae  and  laminae  of  the  cerebellum  seem  to  terminate  in  the  fibres  of  the  mid- 
dle peduncles. 

General  View  of  the  Cerebellum. 

From  the  preceding  statements  we  may  draw  the  following  conclusions  :  The  cerebel- 
lum consists  of  two  lateral  lobes  and  a  middle  lobe  ;  the  lobes  are  formed  by  a  consider- 
able number  of  segments,  which  are  subdivided  into  smaller  segments,  and  these  into 
laminae  and  lamellae  ;  each  lobe  contains  a  central  medullary  nucleus,  upon  which  all  the 
segments  rest,  and  which  constitutes  the  termination  or  the  origin  of  the  several  pedun- 
cles ;  the  substance  of  these  peduncles  is  fibrous  or  fasciculated,  and  that  of  the  central 
nucleus  has  a  similar  character,  but  not  so  well  marked  ;  the  medullary  substance  of 
each  segment  is  formed  by  laminae  applied  to  each  other,  but  not  actually  continuous  ; 
each  of  these  laminae  is  fan-shaped,  and  those  which  constitute  the  central  nucleus  of 
each  segment  become  separated  from  each  other  to  form  the  secondary  segments,  the 
laminae,  and  the  lamellae  ;  the  ultimate  lamellae  of  the  cerebellum  consist  of  two  leaflets 
of  white  matter  covered  externally  by  a  very  thin  yellowish  layer,  which  is  itself  cover- 
ed by  a  rather  thick  layer  of  gray  matter  ;*  the  corpora  dentata,  or  olivary  bodies  of  the 
cerebellum,  consist  of  fibres  or  laminae  of  medullary  substance,  which  are  spread  out  so 
as  to  terminate  at  different  points  upon  the  inner  surface  of  the  dense  yellow  membra- 
nous layer  which  constitutes  their  external  investment. 

A  very  ingenious  explanation  of  the  structure  of  the  cerebellum  has  been  proposed  by 
Gall,  and  is  now  rather  generally  adopted. 

The  opposite  directions  of  the  inferior  and  middle  peduncles  of  the  cerebellum  sug- 
gested to  him  the  idea  of  diverging  and  converging  fasciculi,  and  to  this  he  has  added  his 
theory  regarding  the  ganglia,  which  he  considered  as  apparatuses  of  re-enforcement,  that 
is  to  say,  as  points  of  origin  for  new  fasciculi. 

According  to  Gall,  then,  the  inferior  peduncles  of  the  cerebellum  or  the  restiform  bod- 
ies (n,fig.  274),  which  he  calls  the  primitive  fasciculi  of  the  cerebellum,  are  the  roots,  or 
fasciculi  of  origin  of  the  cerebellum.  After  they  have  penetrated  a  few  lines  into  the 
substance  of  the  organ,  they  meet  with  and  join  the  corpus  dentatum,  which  Gall  regards 
as  a  true  ganglion,  or  apparatus  of  origin  and  re-enforccment  for  a  great  part  of  the  nervous 
mass  of  the  cerebellum.  According  to  him,  a  principal  nervous  fasciculus  corresponds  to 
each  of  the  folds  of  the  corpus  dentatum,  from  which  ganglion  arise  all  those  prolonga- 
tions of  medullary  substance  which,  together  with  the  gray  matter  upon  them,  consti- 
tute the  middle  and  lateral  lobes  of  the  cerebellum. 

Besides  the  preceding  fasciculi,  which  are  named  by  Gall  the  diverging  fasciculi,  and 
are  said  by  him  to  constitute  the  formative  system  of  fibres,  there  are  certain  converging 
fasciculi,  which  constitute  the  uniting  system  of  fibres,  or  the  commissures  of  the  cerebellum. 
These  are  supposed  to  have  no  direct  connexion  either  with  the  primitive  fasciculi  or 
the  corpus  dentatum,  but  to  emanate  from  the  gray  matter  upon  the  surface  of  the  cere- 
bellum, and  to  pass  in  different  directions  (p  q,  fig.  273)  between  the  diverging  fasciculi, 
so  as  to  enter  into  and  constitute  the  middle  peduncles  of  the  cerebellum  (m)  and  the 
pons  Varolii,  which  Gall  regarded  as  forming  together  the  commissure  of  the  cerebellum. 

The  superior  peduncles  of  the  cerebellum  (?•',  fig.  274)  he  considered  as  fasciculi  o*" 
communication  between  the  middle  median  lobe  of  the  cerebellum  and  the  corpora  quad 
rigemina,  and  the  valve  of  Vieussens  as  the  commissure  of  these  peduncles. 

We  can  only  regard  Gall's  view  concerning  the  structure  of  the  cerebellum  as  an  in- 
genious speculation.  Why  should  the  inferior  fasciculi  be  the  roots  or  primitive  bundles 
of  the  cerebellum  rather  than  the  superior  1  Who  has  seen  the  re-enforcement  of  these 
primitive  fasciculi  in  the  corpus  dentatum  1  Why  should  the  corpus  dentatum  be  regard- 
ed as  a  ganglion  1  Whence  is  this  distinction  between  converging  and  diverging  fasci- 
culi 1 1  and,  finally.  Why  are  figure  and  metaphor  employed  in  reference  to  strictly  ana- 
tomical questions  1 

*  [The  white  substance  of  the  laminae  is  said  to  consist  of  two  sets  of  fibres — one  coming  from  the  central 
mass,  and  passing  up  the  centre  of  the  laminie,  and  the  other  set  lying;  upon  the  first,  and  passing  from  one 
lamina  to  another.] 

*  "  These  converging  fibres,"  says  Tiedemann  (French  translation  by  Jourdan,  p.  169j,  "  are  merely  chimer- 


724  NEUROLOGY. 

Another  theory  regarding  the  structure  of  the  cerebellum  has  been  offered  by  Rolan- 
do, who,  by  combining  the  results  derived  from  an  examination  of  the  human  cerebellum, 
when  hardened  in  a  strong  saline  solution,  with  those  furnished  by  the  anatomy  of  the 
brain  of  the  shark,  and  those  obtained  by  studying  the  development  of  the  brain  of  the 
fowl,  was  led  to  regard  the  human  cerebellum  as  formed  by  the  folding  and  refolding  upon 
themselves  of  the  parietes  of  a  large  bladder  or  vesicle,  so  as  to  give  rise  to  innumera- 
ble laminae.* 

The  facts  we  have  already  stated  sufficiently  refute  this  hypothesis.  It  is  quite  cer- 
tain that  the  cerebellum  is  formed  by  the  union  of  one  middle  and  two  lateral  lobes  :  the 
lobes  themselves  are  composed  of  a  considerable  number  of  segments,  which  are  subdi- 
vided into  smaller  segments,  laminae,  and  lamellae.  The  general  structure  of  the  cere- 
bellum is  laminated,  and  these  laminae  are  striated  ;  each  lamella  contains  two  leaflets 
of  white  substance  covered  with  gray  matter.  The  cerebellum  is  connected  with  the 
medulla  oblongata  by  the  inferior  peduncles,  and  with  the  brain  by  the  superior  pedun- 
cles ;  the  middle  peduncles  and  the  transverse  fibres  pf  the  pons  establish  an  intimate 
connexion  between  the  two  lobes  of  the  cerebellum,  t 

Development  of  the  Cerebellum. 

The  cerebellum  does  not  appear  until  some  time  after  the  spinal  cord  :  it  consists,  at 
first,  of  two  laminae  and  plates  prolonged  from  the  cord,  which  approach  each  other  to- 
wards the  median  line  ;  these  are  the  inferior  peduncles  of  the  cerebellum,  or  the  resti- 
form  bodies.  The  human  cerebellum  in  this  condition  has  a  close  resemblance  to  the 
same  organ  in  fishes  and  reptiles.  At  the  fourth  month,  the  cerebellum  forms  a  sort  of 
uniform  girdle,  four  lines  in  width,  around  the  tubercula  quadrigemina  and  the  medulla 
oblongata ;  the  pons  Varolii  is  already  visible  ;  there  is  a  rudiment  of  the  corpus  denta- 
tum,  and  the  surface  of  the  cerebellum  is  entirely  devoid  of  fissures.  At  the  fifth  month 
there  are  four  transverse  fissures :  a  vertical  section  of  the  cerebellum  presents  five 
branches  ;  but  there  are  as  yet  neither  laminae  nor  lamellae,  nor  is  there  any  distinction 
between  the  middle  and  lateral  parts.  At  the  sixth  month,  the  cerebellum  is  divided  by 
the  posterior  notch,  the  different  orders  of  fissures  are  visible,  and  the  corpus  dentatum 
has  acquired  considerable  size.  During  the  last  three  months  of  intra-uterine  existence, 
the  lateral  lobes  generally  acquire  that  predominance  over  the  middle  lobe  which  is  found 
to  hold  after  birth. 

As  the  development  of  the  spinal  cord  precedes  that  of  the  cerebellum,  and  as  the  cer- 
ebellum appears  to  be  formed  by  a  prolongation  of  the  posterior  fasciculi  of  the  cord, 
does  it  follow  that  that  organ  is  a  production  or  an  expansion  of  the  cord  1  Certainly 
not ;  all  that  we  can  conclude  is,  that  they  are  developed  in  succession. 

Reil  and  Tiefdemann  have  advanced  the  opinion  that  the  cerebellum  is  secreted  by  the 
pia  mater,  and  that  the  gray  matter  is  deposited  the  last ;  but  this  is  only  an  assertion 
without  demonstration. 

The  cortical  substance  is  formed  at  the  same  time  as  the  medullary,  and  neither  of 
them  can  be  considered  as  the  product  of  the  other. 

Comparative  Anatomy  of  the  Cerebellum. 

In  fishes  the  cerebellum  is  generally  small,  but  in  the  ray  and  shark  it  is  large,  subdi- 
vided into  convolutions,  and  prolonged  above  the  optic  lobes  in  front,  and  above  the  lobe 
of  the  eighth  pair  of  nerves  behind.  In  the  silures,  as  Weber  has  observed,  the  cere- 
bellum is  relatively  as  large  as  the  human  cerebrum  ;  for  it  covers  the  posterior  half  of 
the  cerebral  lobes,  as  the  cerebrum  in  man  covers  the  cerebellum.  In  all  fishes  the  cer- 
ebellum contains  a  considerable  cavity.  In  some  of  Ihis  class  of  animals  it  is  subdivi- 
ded into  segments,  laminae,  and  lamellae.J 

Reptiles. — There  is  no  cerebellum  in  the  batrachia  (as  in  the  frog,  toad)  and  ophidia 
(serpents) ;  most  anatomists,  however,  admit  its  existence  in  a  rudimentary  state.  It 
is  very  small,  and  shaped  like  a  roof,  or  vaulted,  in  the  chelonians  (tortoise) ;  it  is  very 
long  in  the  saurians  (lizard,  crocodile). 

Birds. — The  cerebellum  is  very  large,  and  represents  an  ellipsoid,  having  its  long  di- 
ameter directed  vertically.  It  is  deeply  and  regularly  traversed  by  horizontal  fissures, 
which  are  curved  downward  on  the  upper  half,  and  upward  on  the  lower  half  of  the  or- 

ical ;  for  the  pons  Varolii,  and  the  meilallary  fibres  of  which  it  consists,  are  found  in  the  foetus  at  the  fourth 
month,  that  is,  at  a  period  when  there  are  no  laminae  nor  lamells,  nor  even  any  leaflets  covered  with  gray  mat- 
ter. Gall,  therefore,  assumes  these  converging-  fibres  to  originate  from  parts  which  do  not  appear  until  after 
those  fibres  themselves."  The  refutation  of  Tiedemami  appears  to  me  to  be  itself  founded  on  an  assumption, 
for  there  is  no  proof  that  the  gray  matter  is  formed  after  the  white. 

"  Osservazioni  sul'  Cerveletto,  p.  187.  In  the  shark,  the  cerebellum  consists  of  a  gray  and  a  white  layer 
united  together  and  folded  a  great  number  of  times  upon  themselves. 

t  It  is  not  yet  ascertained  whether  the  lateral  halves  of  the  cerebellum  act  upon  the  same  or  opposite  sides  of 
the  body  ;  some  cases,  in  which  atrophy  of  one  hemisphere  of  the  cerebrum  coexisted  with  atrophy  of  the  op 
posite  hemisphere  of  the  cerebellum,  would  appear  to  show  that  the  action  of  the  latter  is  not  crossed.  The 
laminated  structure  of  the  cerebellum  and  its  twofold  composition  suggested  to  Rolando  the  idea  of  comparing 
it  to  a  voltaic  pile,  or  electro-motive  apparatus. 

t  [It  is  divided  into  segments  by  deep  transverse  furrows  in  some  cartilaginous  fwhe.^.1 


THE   CEREBRUM.  725 

gan.  They  all  tenninate  opposite  two  small  tubercles  or  appendages,  situated  one  at 
each  extremity  of  the  transverse  diameter.  Upon  a  section  of  the  cerebellum  of  birds 
is  seen  an  arbor  vitae,  composed  of  white  substance  covered  with  gray  matter. 

Mammalia. — In  the  three  classes  already  examined,  the  cerebellum  has  merely  a  mid- 
dle lobe  :  in  all  mammalia  there  are  also  lateral  lobes.  They  are  at  lirst  small,  like  ap- 
pendages, as  in  the  rodentia,  in  which  the  cerebellum  differs  but  little  from  that  of  birds ; 
they  gradually  increase  in  size  as  we  proceed  upward  in  the  scale,  until  they  reach  their 
highest  state  of  perfection  in  man,  the  development  of  whose  cerebrum  and  cerebellum 
exceeds  that  of  the  same  parts  in  all  the  lower  animals.  In  mammalia  the  size  of  the 
lateral  lobes  of  the  cerebellum  is  directly  proportioned  to  that  of  the  oUvary  bodies,  the 
existence  of  which  in  this  class  Vicq  d'Azyr  has  erroneously  denied. 


THE  CEREBRUM,  OR  BRAIN  PROPER. 

Definition — Situation — Size  and  Weight — General  Form. — The  Superior  or  Convex  Surface. 
— The  Inferior  Surface  or  Base — its  Median  Region,  containing  the  Inter-peduncular  Space, 
the  Corpora  Albicantia,  the  Optic  Tracts  and  Commissure,  the  Tuber  Cinereum,  Infundibu- 
lum,  and  Pituitary  Body,  the  Anterior  Part  of  the  Floor  of  the  Third  Ventricle,  the  reflected 
Part  of  the  Corpus  Callosum,  the  Anterior  Part  of  the  Longitudinal  Fissure,  the  Posterior 
Part  of  the  Longitudinal  Fissure,  the  Posterior  Extremity  of  the  Corpus  Callosum  'and  Me- 
dian Portion  of  the  Transverse  Fissure,  and  the  Transverse  Fissure. — The  Lateral  Regions, 
including  the  Fissure  of  Sylvius  and  the  Lobes  of  the  Brain. — The  Convolutions  and  Anfrac- 
tuosities  of  the  Brain,  upon  its  Inner  Surface,  its  Base,  and  its  Convex  Surface — Uses  of  the 
Convolutions  and  Anfractuosities . — The  Internal  Structure  of  the  Brain — Examination  by 
Sections — Horizontal  Sections  showing  the  Corpus  Callosum,  the  Septum  Lucidum,  the  For- 
nix and  Corpus  Fimbriatum,  the  Velum  Interpositum,  the  Middle  or  Third  Ventricle,  the 
Aqueduct  of  Sylvius,  the  Pineal  Gland,  the  Lateral  Ventricles,  their  Superior  and  Inferior 
Portions,  the  Choroid  Plexus,  and  the  Lining  Membrane  and  the  Fluid  of  the  Ventricles — 
Median  Vertical  Section — Transverse  Vertical  Sections — Section  of  Willis. — General  Re- 
marks on  this  Method  of  Examining  the  Brain. — Methods  of  Varolius,  Vieussens,  and 
Gall. — Gall  and  Spurzheim's  Views  on  the  Structure  of  the  Brain. — General  Idea  of  the 
Brain. — Development. — Comparative  Anatomy. 

The  cerebrum  or  brain,  strictly  so  called,  is  that  portion  of  the  encephalon  which  occu- 
pies the  whole  of  the  cavity  of  the  cranium,  except  the  inferior  occipital  fossae.  It  forms, 
as  it  were,  the  crown  or  summit  of  the  spinal  axis,  surmounting  it  {cerebrum  superius), 
and,  at  the  same  time,  lying  in  front  of  (cerebrum  aiiterius)  the  spinal  cord,  as  the  origin 
and  termination  of  which  it  has  been  alternately  regarded.  By  the  pons  Varolii  and  the 
anterior  or  cerebral  peduncles  it  is  intimately  connected  with  the  cerebellum  and  the 
spinal  cord.  The  tentorium  cerebelli  completes  the  cavity  in  which  it  is  enclosed,  and 
separates  it  from  the  cerebellum,  wljich  is  situated  below  its  posterior  lobes.  The  cra- 
oiiim,  the  dura  mater,  the  arachnoid,  and  the  pia  mater  form  a  fourfold  investment  for  it. 

Size  and  Weight  of  the  Cerebrum. 

The  great  size  of  the  cerebrum  is  undoubtedly  one  of  the  most  characteristic  points  in 
the  structure  of  man :  in  several  animals,  the  entire  encephalon  is  relatively  as  large, 
and  even  larger  {ex.,  the  canary  bird,  the  sapajou,  the  dolphin) ;  but  in  reference  to  the 
size  of  the  brain  properly  so  called,  i.  e.,  of  the  cerebral  hemispheres,  even  the  most  fa- 
voured animals  are  much  inferior  to  man.* 

In  the  adult,  the  weight  of  the  cerebrum,  detached  from  the  cerebellum  and  the  pons 
by  a  section  through  its  peduncles,  varies  from  two  to  three  pounds. t  I  believe  it  to  be 
impossible  to  construct  a  table  of  the  comparative  size  and  weight  of  the  brain  and  of  the 
body.  Is  it  not  evident,  indeed,  that  one  element  in  the  comparison,  namely,  the  weight 
of  the  body,  is  subject  to  great  variety  1  Haller  has  recorded  the  results  of  all  the  cal- 
culations which  have  been  made  upon  this  subject,  and  the  diversity  of  those  results  is 
the  best  comment  that  can  be  made  upon  this  mode  of  comparison. 

These  remarks  do  not  apply  to  the  relative  proportions  between  the  cerebrum  and 

•  The  weight  of  the  cerebrum  of  the  horse  and  the  oi  is  scarcely  half  that  of  the  human  cerebrum. 

t  [From  the  statements  given  by  Tiedemanu  (Htm  des  Negers,  <fcc.,  p.  6,  Heidelb.,  1837),  it  appears  that 
the  prevalent  vreight  of  the  brain  (entire  encephalon)  in  the  adult  male  is  about  from  44  to  48  oz.  troy  :  in  the 
adult  female,  from  40  to  44  oz.  The  results  deducible  from  Dr.  Sims's  tables  do  not  materially  differ  from 
the  above. 

In  thirty-nine  males,  varying  in  age  from  22  to  80,  Tiedemann  found  the  minimum  weight  of  the  brain  38  oz. 
20  gr.,  the  maximum  59J  oz. 

In  eleven  females,  from  20  to  80 years  of  age,  the  minimum  was  32  oz.  5  drs.  50  grs.,  the  maiimum  46  oz.  2  drs. 

Th»eitremes,  according  to  Dr.  Sims's  observations,  were  in  about  seventy  males  from  20  to  91  years,  lowest, 
33  oz.  80  grs. ;  highest,  54 "oz.  6  drs.,  troy  weight.  In  ninety  females,  between  the  ages  of  20  and  89,  the  low- 
est was  27  oz.  80  grs.,  the  highest  51  oz.  6  drs.] 


726  NEUROLOGY. 

cerebellum.  According  to  my  own  observations,  the  weight  of  the  cerebellum  is  from 
the  twelfth  to  the  eighth  part  of  that  of  the  cerebrum.* 

It  is  important  to  obtain  some  approximation  to  the  relative  size  of  the  brain  in  differ- 
ent individuals  in  the  two  sexes,  and  at  different  ages. 

It  results,  from  a  great  number  of  facts,  that  the  size  of  the  brain  is  independent  of  the 
stature  of  the  individual ;  that  the  size  of  the  brain  is  also  independent  of  sex,  although, 
since  the  time  of  Aristotle,  it  has  been  the  custom  to  repeat  that  the  female  brain  is 
smaller  than  that  of  the  male ;  that  in  the  fcetus  and  the  infant  the  cerebellum  is  rela- 
tively much  larger  than  the  adult ;  and  that  in  old  age  the  brain  is  often  atrophied  like 
other  organs,  and  then  does  not  completely  fill  the  cranial  cavity. 

Can  the  size  of  the  brain  be  increased  by  exercise,  and  diminished  by  inaction  1  It 
cannot  be  doubted  that  the  brain  must,  in  this  respect,  obey  the  laws  which  regulate  all 
other  organs ;  but  the  bony  parietes  of  the  cranium  must  offer  great  obstruction  to  its 
development ;  indeed,  examples  have  been  recorded  of  compression  of  the  brain,  and 
even  of  death,  produced  by  hypertrophy  of  this  organ. 

If  it  be  true  that  the  power  of  an  organ  depends  upon  its  size,  it  follows  that  the  size 
of  the  brain,  and,  consequently,  the  capacity  of  the  cranium,  must  have  a  tolerably  close 
ralation  to  the  development  of  the  cerebral  functions ;  but  the  activity  of  these  functions 
is  connected  with  so  many  circumstances  besides  the  size  and  quantity  of  brain,  that 
any  estimate  of  the  intellectual  powers  founded  exclusively  upon  these  data  is  very  often 
faulty  and  inexact,  t 

The  Specific  gravity  of  the  brain,  as  compared  with  that  of  water,  is,  according  to  Mus- 
chenbroek,  as  1030  to  1000.  It  would  be  interesting  to  determine  whether  its  specific 
gravity  varies  according  to  age  and  in  disease,  and  also  whether  it  differs  in  different 
animals.  According  to  Soemmering,  the  specific  gravity  of  the  brain  in  old  persons  is 
less  than  in  those  of  middle  age. 

General  Form  of  the  Cei'ehrum, 

The  form  of  the  cerebrum  corresponds  exactly  to  that  of  the  cranial  cavity,  which  is, 
as  it  were,  moulded  on  it ;  it  is,  therefore,  variable  like  that  of  the  cavity  itself,  which, 
during  early  infancy,  is  capable  of  assuming  all  sorts  of  shapes  from  the  application  of 
external  pressure. 

If  the  entire  cranial  cavity,  exceping  the  posterior  occipital  fossae,  be  filled  with  plas- 
ter of  Paris,  an  exact  representation  will  be  obtained  of  the  general  form  of  the  brain 
which  had  been  removed.  The  cerebrum,  therefore,  is  like  the  cranium  of  an  ovoid  fig- 
ure, having  its  large  end  turned  backward,  and  its  small  one  forward.  It  is  divided  on 
its  under  surface  into  lohes,  which  occupy  the  different  compartments  in  the  base  of  the 
cranium.  The  entire  surface  is  marked  by  deep  tortuous  furrows  (see  Jigs.  276,  282), 
called  anfractuosities,  which  occasion  an  appearance  like  that  of  the  convolutions  of  the 
small  intestines,  and  hence  the  term  convolutions  is  applied  to  the  eminences  resembling 
folds,  by  which  the  anfractuosities  are  bounded. 

The  Superior  or  Convex  Surface  of  the  Brain. 

A  median  vertical  fissure  running  from  before  backward,  called  the  longitudinal  fi^ssure, 
divides  the  cerebrum  into  two  exactly  similar  lateral  halves,  which  are  improperly  called 
cerebral  hemispheres,  for  each  of  them  resembles  the  fourth  part  of  an  ovoid  ;  but  would 
be  more  correctly  designated  the  right  and  left  brain,  as  was  done  by  Galen.j  The  lon- 
gitudinal fissure  divides  the  cerebrum  in  its  whole  depth,  both  in  front  and  behind  (x  y, 
fig.  277 ;  also  fig.  282) ;  but  in  the  middle  it  is  interrupted  by  the  corpus  callosum  {d  d). 
There  are  two  brains,  as  there  are  two  spinal  cords  and  two  cerebella.^ 

The  cerebrum  is  therefore  symmetrical,  but  it  is  less  completely  so  than  the  spinal  cord ; 
I  should  even  say  that  a  decided  disproportion  is  very  commonly  observed  between  the 
right  and  left  hemispheres.  It  does  not  appear  that  this  want  of  symmetry  exerts  that 
influence  upon  the  intellectual  faculties  which  was  imagined  by  the  ingenious  Bichat, 
whose  own  unsymmetrical  brain  was  in  direct  contradiction  to  his  doctrine.  It  is,  nev- 
ertheless, possible  that  a  want  of  symmetry,  when  carried  to  a  certain  point,  may  affect 
the  intellect ;  in  the  brains  of  several  idiots,  their  want  of  symmetry  has  been  very  re- 

*  In  three  young  subjects  I  found  as  follows : 


lb. 

oz. 

oz 

Cerebrum     . 

.     .     2 

2 

Cerebellum    . 

•  ^ 

it 

.    .    2 

8k 

" 

.    3J 

"         .     . 

.    .    2 

5 

" 

.    5 

+  Persons  endowed  with  strong  memories  have  always  appeared  to  me  to  have  large  brains  ;  and  the  part 
which  the  memory  performs  in  the  exercise  of  mind  is  of  such  a  nature  that  we  cannot  be  surprised  if  the  persons 
alluded  to  are  frequently  men  of  superior  intellect.  I  have  known  many  persons,  having  heads  of  considera- 
ble size,  who  had  merely  a  good  memory,  but  none  of  the  characteristics  of  genius.  Those  in  whom  tlie  braiu 
is  large  seem  to  me  to  resist  the  power  of  disease  better  than  sucli  as  have  small  brains. 

}  Chaussier  applies  the  terra  lobe  to  the  hemispheres,  reserving  that  of  lobule  for  the  secondary  divisions. 

<)  Galen  inquires  why  there  should  be  two  brains  ;  and  replies,  that  it  is  to  ensure  a  more  perfect  p^form- 
*nce  of  the  cerebral  functions.  I  have  seen  several  hemiplegic  individuals  in  whom  the  whole  of  one  hemi- 
sphere was  atrophied,  but  who,  notwithstanding,  possessed  ordinary  intellectual  faculties. 


THE    BASE    OF    THE   BRAIN. 


727 


markable.     I  have  seen  the  longitudinal  fissure  of  the  brain  deviate  to  the  right  or  left 
Bide  at  an  angle  of  from  15°  to  20°  degrees  from  its  usual  direction. 

Each  cerebral  hemisphere  presents  three  surfaces  for  our  consideration  : 

An  internal  surface  {fig.  282),  which  is  flat,  vertical,  and  separated  from  that  of  the 
opposite  hemisphere  by  the  falx  cerebri ;  but  as  the  falx  does  not  extend  so  low  as  the 
corpus  callosum,  it  follows  that  the  two  hemispheres  are  in  contact  below,  the  pia  mater, 
however,  intervening  between  them.  In  those  rare  cases  of  absence  of  the  falx  cerebri, 
the  corresponding  faces  of  the  two  hemispheres  are  in  contact  with  each  other  through 
out  their  whole  extent.  I  have  seen  one  case  in  which  the  falx  was  imperfect,  and  the 
two  hemispheres  were  united. 

An  external  surface,  which  is  convex,  and  resembles  the  surface  of  the  fourth  part  ot 
an  ovoid,  having  its  great  end  directed  backward ;  it  corresponds  to  the  concavity  formed 
by  the  frontal,  parietal,  and  occipital  bones. 

An  inferior  surface,  which  forms  part  of  the  base  of  the  brain  in  general,  and  will  be 
next  described. 

The  Inferior  Surface  or  the  Base  of  the  Brain. 

The  hase  of  the  brain  {fig.  276),  admirably  described  and  correctly  figured  bv  Soemmer- 
ing in  a  special  treatise  upon  the  p^^^  276. 
subject,*  presents  a  great  number 
of  objects  for  our  consideration.  In 
order  to  obtain  a  perfect  knowledge 
of  it,  it  is  advisable  to  examine  it 
while  the  brain  is  still  enclosed  in 
its  membranes,  and  placed  in  the 
scull-cap,  with  its  base  uppermost ; 
and  also  upon  a  brain  from  which 
the  membranes  have  been  remo- 
ved, and  which  is  placed  in  the 
same  position,  but  on  a  flat  surface. 
In  the  former  case,  the  parts  form- 
ing the  base  of  the  brain  are  press- 
ed together,  and  may  be  studied  as 
a  whole  ;  and  in  the  latter,  they  are 
separated,  and  may  be  examined  in 
detail. 

It  is  at  its  base  that  the  brain  i 
connected  with  the  other  parts  o 
the  cerebro-spinal  axis  by  means 
of  the  right  and  left  peduncles  {ff), 
which  may  be  regarded  as  the  roots 
of  the  two  hemispheres. 

The  Median  Region. — In  the  me- 
dian line,  opposite  the  centre  of 
the  base  of  the  brain,  and  in  front 
of  the  pons  Varolii  (d),  is  situated 
an  excavation,  which  may  be  called 
the  median  excavation  of  the  base  of 
the  brain.  This  excavation  has  already  been  alluded  to  in  the  description  of  the  arach- 
noid membrane  and  the  sub-arachnoid  fluid,  with  which  this  excavation  is  filled  :  it  is 
formed  by  the  brain  being  curved  upon  itself,  and  is  partially  effaced  when  that  organ 
is  placed  with  its  base  uppermost  upon  a  flat  surface :  this  excavation  is  of  a  pyram- 
idal form,  the  apex  being  directed  upward  and  the  base  downward.  The  borders  of 
the  excavation  form  a  hexagon,  and  contain  the  arterial  hexagon  of  the  base  of  the  cra- 
nium, named  the  circle  of  Willis.  The  posterior  borders  of  the  hexagon  are  formed  by 
the  peduncles  of  the  brain,  the  lateral  borders  by  the  inner  part  of  the  posterior  lobes  [c, 
middle  lobest]  of  the  cerebrum,  and  the  anterior  borders  by  the  inner  and  back  part  of 
the  anterior  lobes  {a)  of  the  cerebrum. 

From  the  six  angles  of  this  hexagon,  six  furrows  proceed  in  different  directions :  from 
the  anterior  angle,  the  fissure  which  separates  the  anterior  lobes,  or  the  great  longitudi- 
nal fissure  {x)  of  the  brain ;  from  the  two  anterior  lateral  angles,  the  corresponding  fis- 
sures of  Sylvius  (y  y) ;  from  the  posterior  lateral  angles,  the  two  extremities  (external  to 
//)  of  the  great  cerebral  fissure,  or  great  transverse  fissure  of  the  brain  ;  and  from  the  pos- 
terior angle  (r),  which  corresponds  to  the  interval  between  the  cerebral  peduncles,  the 
longitudinal  groove  {d)  upon  the  pons  Varolii. 

*  Do  basi  Encephali  (Luduiig,  Scriptores  Neurologici,  t.  ii.). 

+  /.  e.,  of  the  middle  lobes  of  anatomists  generally  {c,fig.  276),  which,  it  must  be  remembered,  the  author, 
agreeing  with  Soimraering,  does  not  regard  as  distinct  from  the  posterior  lobes  (b),  and  to  which,  therefore, 
he  does  not  apply  the  term  "  middle  lobes."  This  term  is,  however,  for  the  most  part  added  [between  brack- 
et*] in  the  translation,  as  it  is  generally  used  in  anatomical  descriptions  in  this  country. 1 


728  NEUROLOGY. 

In  the  area  of  this  median  excavation  are  seen  the  inter-pcduncular  space  (above  r),  the 
mammillary  tubercles  {z,  corpora  matnmillaria  vel  albicaniia),  the  oplic  tracts  («)  and  optic 
commissure  (t),  the  posterior  part  of  the  floor  of  the  third  ventricle,  or  the  tuber  cinereum  {v), 
the  infundibulum  (i),  and  the  pituitary  body* 

In  front  of  the  median  excavation  are  situated,  counting  from  behind  forward,  the  an- 
terior part  of  the  floor  of  the  third  ventricle  {lamina  cinerea,  m,fig.  282),  the  under  or  reflect- 
ed portion  of  the  corpus  callosum  (e),  and  the  inferior  part  of  the  longitudinal  fissure  of  the 
cerebrum  (x,  flg.  276). 

Behind  the  median  excavation  is  the  pons  Varolii,  and,  behind  that,  the  middle  part 
(r,  fig.  282)  of  the  great  transverse  fissure,  by  which  the  pia  mater  enters  (above  p)  the 
third  ventricle,  the  thick  posterior  extremity  (/)  of  the  corpus  callosum,  and  the  posterior 
part  of  the  longitudinal  fissure  of  the  cerebrum. 

The  Lateral  Regions  of  the  Base  of  the  Brain. — Upon  each  of  these  regions  are  seen  the 
inferior  surface  of  the  corresponding  anterior  lobe  (a)  of  the  cerebrum,  the  fissure  of  Sylvius 
(y),  by  which  this  lobe  is  separated  from  the  posterior  lobe  [middle  lobe  of  others,  c],  and 
the  inferior  surface  of  the  posterior  lobe  itself  (c  b).     There  is  no  distinct  middle  lobe.t 

I  shall  now  describe,  successively  and  in  detail,  the  several  parts  just  enumerated, 
with  the  exception  of  the  cerebral  peduncles  and  the  pons  Varolii,  which  have  already 
been  noticed  as  constituent  parts  of  the  isthmus  of  the  encephalon. 

The  Median  Region  of  the  Base  of  the  Brain. 
The  Inter-peduncular  Space. 
This  space  (above  r)  is  of  a  gray  colour,  it  is  perforated  by  numerous  openings  for  the 
transmission  of  vessels,  and  is  termed  the  middle  or  posterior  perforated  spot  {locus  per- 
foratus) ;  it  contains  the  origin  of  the  third  pair  of  nerves  (3).  A  longitudinal  groove 
and  two  fasciculi,  separated  from  the  corresponding  cerebral  peduncle  by  a  blackish  line, 
are  seen  in  this  spot.  These  inter-peduncular  fasciculi  are  forrhed  by  a  prolongation  of 
the  fasciculi  of  re-enforcement  {faisceaux  innomines)  of  the  medulla  oblongata. 

The  Corpora  Albicantia. 

The  mammillary  tubercles  {corpora  albicantia  vel  mammillaria,  z)  are  two  small  pisiform, 
or,  rather,  hemispherical  globules,  composed  externally  of  white,  and  internally  of  gray 
substance,  situated  behind  the  tuber  cinereum,  which  is  accurately  adapted  to  their  an- 
terior surface,  also  behind  the  infundibulum,  and  between  the  peduncles  of  the  brain. 
They  are  separated  from  each  other  by  a  deep  fissure,  excepting  at  their  highest  part, 
where  they  are  connected  by  means  of  a  thin  layer  of  gray  matter,  which  is  very  easily 
torn  ;  they  correspond  {z,  fig.  282)  to  the  floor  of  the  third  ventricle  (/). 

It  will  be  hereafter  seen  that  the  white  cov.ering  of  these  small  bodies  is  formed  by  the 
termination  of  the  anterior  pillars  of  the  fornix,  and  hence  the  name  given  them  by  Cas- 
serius,  the  bulbs  of  the  anterior  pillars  of  the  fornix  {bulbi  priorum  crurum  fornicis),  a 
name  which  should  be  preserved.  The  two  corpora  albicantia  are  generally  of  equal 
size.  In  several  cases  of  atrophy  of  one  of  the  hemispheres  of  the  cerebrum,  I  have 
found  the  corresponding  mammillary  tubercles  also  atrophied. 

We  are  completely  ignorant  of  the  function  of  these  bodies. 

In  man  and  the  carnivora  only  are  there  two  mammillary  tubercles,  and  in  all  the  oth- 
er vertebrata  there  is  but  one.  They  attain  their  highest  state  of  development  in  fishes, 
if,  as  stated  by  Vicq  d'Azyr,  they  are  represented  by  the  two  larger  lobes,  which  occupy 
a  corresponding  situation  in  that  class  of  animals.  During  the  early  periods  of  foetal 
life  they  are  blended  together  into  one  tolerably  large  mass,  and  do  not  become  distinct 
from  each  other  until  about  the  seventh  month. 

The  Optic  Tracts  and  Comm,issure. 
At  the  point  where  the  peduncles  of  the  cerebrum  pass  into  the  brain,  each  of  them  is 
surrounded  by  a  white  band,  named  the  optic  trad,  or  tract  of  the  optic  nerve.  Each  of 
those  tracts  commences,  behind,  at  an  eminence  called  the  corpus  geniculatum  externum 
{JifiS-  271),  which  will  be  seen,  hereafter,  to  be  an  appendage  of  that  part  of  the  brain 
named  the  optic  thalamus.  The  corpus  geniculatum  internum  {i,figs.  271,  272)  of  au- 
thors is  merely  a  tubercle  inserted  into  the  bend  or  knee  formed  by  the  corpus  genicula- 
tum externum.  The  optic  tract  (2,  fig.  272),  then,  is  the  continuation  of  the  corpus  ge- 
niculatum externum,  from  which  it  is  distinguished  by  its  whiteness,  which  contrasts 
strongly  with  the  gray  colour  of  that  body :  it  is  at  first  broad,  flattened,  and  thin,  and 
is  applied  to  the  corresponding  cerebral  peduncle,  being  distinguished  from  the  peduncle 
only  by  the  direction  of  its  fibres.  It  then  turns  horizontally  around  the  peduncle,  is  de- 
tached from  it,  and  at  the  same  time  becomes  narrower  and  thicker ;  having  reached 
the  front  of  the  peduncle,  it  changes  its  direction,  passes  forward  and  inward  {s,fig.  276), 
and  is  united  with  its  fellow  of  the  opposite  side,  to  form  the  commissure  or  chiasma  {t) 
of  the  optic  nerves  (2).  The  optic  tracts  may  be  regarded  as  forming  a  commissure  to 
the  two  optic  thalami. 

*  [To  avoid  confusion  in  the  drawinfr,  the  pituitary  body  is  not  represented  mfig.  276  ;  its  point  of  attncb 
meut  is  to  the  infundibulum  (i).]  +  See  note,  p.  "27. 


THE  BASE  OF  THE  BRAIN.  729 

These  tracts  and  the  cerebral  peduncles  of  the  two  sides  enclose  a  lozenge-shaped  in- 
terval, in  which  are  situated  the  posterior  perforated  spot,  the  corpora  albicantia,  the  tu- 
ber cinereum,  the  infundibulum,  and  the  pituitary  body. 

The  Tuber  Cinereum,  the  Infundibulum,  and  the  Pituitary  Body. 

The  terra  tuber  cinereum  (»)  has  been  apphed  by  Soemmering  to  the  soft  gray  mass 
which  occupies  the  triangular  interval  between  the  corpora  albicantia  and  the  optic 
tracts.  It  is  also  called  the  floor  of  the  third  ventricle,  because  it  closes  that  cavity  be- 
hind and  below,  and  the  base  of  the  infundibulum,  because  that  part  is  attached  to  it. 

The  infundibulum  (la  tige  pituitaire,  Lieutaud;  la  tige  sus-sphenoidale,  Chauss.)  is  a 
reddish  process  (i),  about  two  lines  in  length,  directed  very  obliquely  downward  and  for- 
ward (i,  fig.  282),  and  applied  to  the  lower  surface  of  the  tuber  cinereum  :  it  is  broad  at 
its  upper  extremity,  but  soon  diminishes  in  diameter,  and  descends,  to  be  inserted  into, 
and  become  continuous  with,  the  pituitary  body. 

Is  the  infundibulum  hollow,  or  is  it  a  solid  stem  1  The  term  infundibulum,  or  funnel, 
applied  to  this  part  by  the  older  anatomists,  and  the  following  synonymes,  pelvis  colatoria, 
scyphus,  aquce  ductus,  encephali  sentina,  afford  ample  evidence  of  both  their  anatomical 
and  physiological  views  regarding  it.  Galen  and  Vesalius,  who  are  so  often  at  variance, 
are  perfectly  agreed  upon  this  subject,  and  describe  the  infundibulum  with  a  minute  ex- 
actness ;  but  since  the  communication  supposed  by  Galen  to  exist  between  the  nasal 
fossae  and  the  brain  by  means  of  passages  through  the  ethmoid  and  sphenoid  bones,  and 
the  equally  hypothetical  communication  admitted  by  Vesalius,  are  known  to  have  no  ex- 
istence, anatomists  have  rejected  the  notion  of  the  passage  of  a  fluid  from  the  brain  in 
this  direction,  and  they  no  longer  regard  the  infundibulum  as  a  funnel  intended  for  its 
transmission.  Haller  has  collected,  in  some  learned  notes,  the  contradictory  opinions 
of  his  predecessors,  but  has  left  the  question  still  in  doubt.  Nor  has  Soemmering  him- 
self, after  a  long  detail  of  investigation  into  the  subject,  arrived  at  a  more  satisfactory 
result.* 

A  careful  examination  of  the  infundibulum  has  convinced  me  that  there  is,  at  least  in 
a  certain  number  of  cases,  a  funnel-shaped  canal,  precisely  similar  to  that  which  was 
described  and  figured  by  Vesalius :  it  is  wide  above,  where  it  communicates  with  the 
third  ventricle,  and  narrow  below,  where  it  reaches  the  pituitary  body,  a  body  which  the 
ancients  had  not  named,  but  which  Vesalius  called  glan^  pituitam  excipiens.  In  order  to 
demonstrate  this  canal,  the  optic  tract  must  be  turned  backward,  and  the  semi-transpa- 
rent corneous  lamina,  which  forms  the  anterior  part  of  the  floor  of  the  third  ventricle, 
must  be  divided ;  behind  a  white  band,  which  is  quite  distinct  from  the  anterior  com- 
missure of  the  brain,  there  is  then  seen  a  circular  opening  sufficiently  wide  to  admit  the 
blunt  end  of  a  large  probe,  which  may  accordingly  be  passed  through  the  entire  length 
of  the  infundibulum  as  far  as  the  pituitary  body.  Again  :  by  cutting  the  infundibulum 
across,  and  then  blowing  upon  it  through  a  blowpipe,  or  letting  some  drops  of  water 
fall  upon  it,  a  perfectly  circular  opening  may  be  demonstrated,  which  cannot  be  produced 
by  the  means  employed  in  the  demonstration. 

Lastly,  we  may  adopt  the  method  of  Vesalius,  who  filled  the  third  ventricle  with  a 
coloured  liquid,  which  soon  reached  the  pituitary  body.  The  same  experiment  succeeds 
still  better  with  mercury.  Nevertheless,  I  ought  to  state,  that  in  two  cases  of  dropsy 
of  the  third  ventricle,  no  fluid  escaped  from  the  infundibulum  when  it  was  cut  across. 

It  is  easy  to  show  the  structure  of  the  infundibulum.  A  fibrous  and  vascular  mem- 
brane, continuous  with  the  pia  mater,  forms  its  external  covering,  and  this  is  lined  by 
a  thin  layer  of  gray  matter,  which  is  continuous  with  that  of  the  floor  of  the  third  ven- 
tricle.    This  gray  matter  forms  a  solid  cord  when  the  infundibulum  is  not  tubular. 

The  pituitary  bodyi  is  a  small  body,  weighing  from  five  to  ten  grains,  which  occupies 
the  sella  turcica,  or  supra-sphenoidal  fossa  (appendice  sus-sphenoidale  du  cerveau, 
Chauss. ;  hypophysis.  Seem.).  The  better  to  appreciate  its  size,  it  is  convenient  to 
break  down,  with  a  chisel,  the  quadrilateral  plate  which  forms  the  posterior  wall  of  the 
sella  turcica  or  pituitary  fossa,  and  which  is  itself  hollowed  in  front,  so  as  to  increase  the 
antero-posterior  diameter  of  that  cavity.  J 

Enclosed  in  the  sella  turcica,  the  pituitary  body  is  kept  in  that  situation  on  each  side 
by  the  fold  of  the  dura  mater,  which  constitutes  the  cavernous  sinus,  and  above  by  a 
portion  of  the  same  membrane,  which  forms  a  circular  orifice  around  tlie  infundibulum. 

The  coronary  sinus,  which  is  situated  between  the  pituitary  body  and  the  margin  of 
the  sella  turcica  in  front  and  behind,  and  the  cavernous  sinuses  on  each  side,  form  a 
vascular  circle  around  this  body,  but  it  is  not  bathed  in  the  blood,  as  stated  by  some. 

*  Ludwig-,  Script.  Neurolog. ;  Soemmering,  De  basi  Encephali,  p.  41.  "  Quibus  omnibus  absque  partiwa 
studio  rite  mecum  perpensis,  non  potui  non  complecti  illorura  virorum  sententiam,  qui  infundibulum,  si  non 
perfecte  solidum,  certe  non  adeo  conspicuo,  uti  veteres  opinati  sunt,  canali  perforatum  esse,  censuerunt." 
Hunter  and  Cruickshank  say  that  the  infundibulum  is  sometimes  solid,  and  sometimes  tubular. 

t  Not  shown  in  figs.  276,  282. 

t  In  order  to  obtain  a  perfect  examination  of  the  pituitary  body  and  infundibulum,  it  is  well  to  sacrifice  a 
brain  and  the  base  of  the  cranium,  and  to  remove,  by  a  circular  incision,  the  body  of  the  sphenoid  bone,  to- 
gether with  the  corresponding  part  of  the  base  of  the  brain. 

4Z 


7^  NEUROLOGT? 

The  upper  surface  of  the  pituitary  body  is  slightly  excavated,  still  it  is  not  unfrequent- 
ly  convex,  so  as  to  project  more  or  less  above  the  level  of  its  fossa. 

On  removing  the  pituitary  body,  it  is  seen  to  be  formed  of  two  distinct  lobes,  of  which 
the  anterior  is  the  larger,  while  the  posterior  occupies  the  small  cavity  in  the  quadrilat- 
eral plate.  These  two  lobes  have  been  very  well  described  by  the  brothers  Wenzel ; 
they  are  not  of  the  same  colour,  the  posterior  lobe  being  grayish  white,  like  the  gray 
substance  of  the  brain,  and  the  anterior  yellowish  gi-ay. 

If  the  anterior  lobe  be  pressed  between  the  fingers,  a  yellowish-white  pulp  escapes 
from  it,  very  nearly  resembling  mixed  plaster  of  Paris.  An  antero-posterior  section  of 
the  pituitary  body  shows,  also,  that  the  two  lobes  are  perfectly  distinct,  being  separated 
by  a  fibrous  layer.  They  are  provided  with  a  great  number  of  small  vessels.  It  has 
been  stated,  but  not  proved,  that  the  infundibulum  contains  two  canals,  one  for  the  an- 
terior, and  the  other  for  the  posterior  lobe.  It  is  extremely  rare  to  find  any  hard  con- 
cretions in  the  pituitary  body  like  those  met  with  in  the  pineal  gland. 

It  is,  perhaps,  not  uninteresting  to  remark,  that  the  pituitary  body  is  most  highly  de- 
veloped in  fishes,  in  which  animals  it  forms  a  true  lobe ;  and  that  it  is  proportionally 
more  developed  in  mammalia,  birds,  and  reptiles,  than  in  the  human  subject.  It  is  hol- 
low in  all  the  lower  animals. 

It  is  larger  at  the  fourth,  fifth,  and  sixth  months  of  foetal  life  than  after  birth,  and  con- 
tains a  cavity  which  communicates  with  the  third  or  middle  ventricle.  I  pnce  found  a 
considerable  cavity  in  the  pituitary  body  of  an  adult. 

The  functions  of  the  pituitary  body  are  enveloped  in  the  greatest  obscurity.  Its  con- 
stancy in  all  vertebrated  animals  and  its  great  vascularity  are  sufficient  evidence  of  its 
importance.  It  certainly  conamunicates  with  the  third  ventricle,  but  for  what  purpose  % 
Does  it  pour  a  peculiar  fluid  into  that  cavity,  or  does  it  absorb  a  portion  of  the  ventricu- 
lar fluid  1  Whatever  may  be  the  use  of  the  communication  just  alluded  to,  the  pituitary 
body  does  not  communicate  directly  with  the  venous  sinuses  around  it :  it  is  not  a  lym- 
phatic gland,  as  maintained  by  Monro  ;  nor  is  it  a  nervous  ganglion  of  the  great  sympa- 
thetic, as  some  have  recently  conjectured,  because  they  fancied  they  saw  some  very  fine 
nervous  filaments  anastomosing  upon  it.  The  branches  of  the  fifth  and  sixth  nerves, 
which  Litre  and  Lieutaud  say  they  have  seen  penetrating  this  body,  have  not  been  de- 
monstrated. 

The  Anterior  Part  of  the  Floor  of  the  Third  Ventricle. 

The  anterior  part  {m,  Jig.  282)  of  the  floor  of  the  third  ventricle,  which  cannot  be  well 
seen  until  the  commissure  of  the  optic  nerves  is  turned  backward,  forms  an  inclined 
plane  directed  downward  and  backward.  It  consists  of  a  fibrous  layer,  which  is  contin- 
uous with  the  neurilemma  of  the  optic  nerves  ;  and  of  a  very  thin,  semi-transparent,  but 
very  strong  corneous  layer  {lamina  cimrea),  from  which  prolongations  are  given  off  to 
the  upper  surface  of  the  optic  commissure,  and  continued  upon  the  optic  nerves  :  these 
prolongations  might  be  called  the  gray  roots  of  the  optic  nerves.  On  dividing  this  horny 
layer,  the  third  ventricle  (I)  is  laid  open  ;  and  it  is  seen  that  this  layer  forms  a  part  of 
the  general  system  of  gray  substance,  which,  on  the  one  hand,  is  prolonged  upon  the  lat- 
eral wall  of  the  third  ventricle,  and  surrounds  the  anterior  pillars  of  the  fornix,  and,  on 
the  other,  is  continuous  with  the  tuber  cinereum,  above  the  optic  commissure. 

The  Reflected  Portion  of  the  Corpus  Callosum. 

In  front  of  the  anterior  part  of  the  floor  of  the  third  ventricle  is  a  transverse  white 
mass,  which  is  nothing  more  than  the  fore  part  (e  to  m)  of  the  reflected  corpus  callosum. 
Terminating  at  this  cross  tract  are  two  white  fasciculi,  which  commence  on  each  side 
at  the  point  where  the  corresponding  fissure  of  Sylvius  meets  the  great  transverse  fis- 
sure of  the  brain ;  they  then  pass  inward  and  forward,  along  the  outside  of  the  optic 
tracts,  form  the  lateral  boundaries  of  the  anterior  part  of  the  floor  of  the  third  ventricle, 
and  terminate  by  becoming  applied  to,  but  not  blended  with  each  other,  behind  the  re- 
flected portion  of  the  corpus  callosum.  Vicq  d'Azyr  has  described  these  bands  as  the 
veduncles  of  the  corpus  callosum. 

The  Anterior  and  Inferior  Part  of  the  Longitudinal  Fissure. 

This  (x,  fig.  276)  is  situated  in  front  of  the  reflected  })ortion  of  the  corpus  callosum, 
and  can  only  be  seen  in  its  entire  extent  after  the  removal  of  a  very  dense  fibrous  layer 
which  connects,  sometimes  very  firmly,  the  back  part  of  the  right  and  left  anterior  lobes 
of  the  cerebrum.  Not  unfrequently  one  of  these  lobes  is  seen  to  encroach  upon  the  oth- 
er :  the  falx  cerebri,  which  is  very  narrow  in  front,  occupies  only  a  very  small  portion 
of  this  fissure. 

All  the  parts  belonging  to  the  median  region  of  the  base  of  the  brain,  which  we  have 
hitherto  described,  are  situated  in  front  of  the  pons  Varolii ;  those  which  remain  to  be 
examined  are  placed  behind  it :  they  are,  counting  from  behind  forward,  the  back  part  of 
the  longitudinal  fissure,  the  posterior  extremity  of  the  corpus  callosum,  and  the  great  horizontal 
or  transverse  fissure. 


THE  BASE  OF  THE  BRAIN.  781 

The  Back  Part  of  the  Longitudinal  Fissure. 
This  is  bounded  in  front  by  the  posterior  extremity  of  the  corpus  callosum  (/) ;  and  as 
that  extremity  is  at  a  greater  distance  from  the  back  of  the  cerebrum  than  the  anterior 
extremity  of  the  corpus  callosum  is  from  the  front  of  the  brain,  it  follows  that  the  back 
part  of  the  longitudinal  fissure  is  of  much  greater  extent  than  the  fore  part  (see  Jigs.  277, 
282).  Moreover,  this  part  of  the  fissure  is  free  throughout  its  whole  extent,  for  it  is  en- 
tirely occupied  by  the  base  of  the  falx  cerebri,  while  the  fore  part  is  only  partially  filled 
with  the  apex  of  the  falx  :  it  might  even  be  said  that  the  posterior  lobes  have  a  tenden- 
cy to  separate  from  each  other  in  this  situation. 

The  Posterior  Extremity  of  the  Corpus  Callosum,  and  Middle  Portion  of  the  Great  Trans- 
verse Fissure. 

The  posterior  extremity  {f,flg.  282)  of  the  corpus  callosum  is  named  the  bourrelet,*  in 
consequence  of  its  being  so  much  enlarged.  This  enlarged  extremity,  which  we  shall 
afterward  find  is  continuous  with  the  posterior  pillars  of  the  fornix,  constitutes  the  up- 
per border  of  a  fissure  (r),  the  lower  border  of  which  is  formed  by  the  tubercula  quadri- 
gemina  {f  g).  The  pia  mater  (r  to  near  k)  enters  at  this  median  fissure,  and  forms  the 
velum  interpositum,  or  tela  choroidea :  in  this  situation,  also,  is  found  the  conarium  or  pi- 
neal gland ;  and  it  is  here  that  Bichat  described  the  orifice  of  his  arachnoid  canal.  This 
median  fissure  becomes  continuous  with  a  lateral  fissure  on  each  side,  so  as  to  form  the 
great  transverse  cerebral  fissure. 

The  Great  Transverse  Cerebral  Fissure. 

The  great  cerebral  fissure  {Bichat),  or  the  great  transverse  or  horizontal  fissure,  follows  a 
semicircular  direction,  having  its  concavity  directed  forward  ;  it  commences  at  the  fis- 
sure of  Sylvius  on  one  side  {h,fig.  276  ;  above  2,  fig.  282),  turns  round  the  opposite  cere- 
bral peduncle,  and  ends  at  the  opposite  Sylvian  fissure. 

The  peduncle  of  the  cerebrum  and  the  optic  thalamus  may  be  regarded  as  forming  the 
root  of  each  cerebral  hemisphere.  Now  the  lateral  part  of  the  great  transverse  fissure 
passes  round  the  posterior  half  of  this  root,  because  it  is  in  this  situation  that  the  cor- 
responding cerebral  hemisphere  is  turned  inward  upon  itself  It  is  this  reflected  and 
concave  surface  of  the  hemisphere  that  forms  the  outer  border  of  the  corresponding  lat- 
eral portion  of  the  transverse  fissure,  while  the  optic  thalamus  forms  its  inner  border. 
This  fissure  communicates  directly  with  the  inferior  cornua  of  the  lateral  ventricles,  and 
through  it  the  pia  mater  enters  those  ventricles,  to  form  the  internal  pia  mater  of  the  brain. 

The  Lateral  Regions  of  the  Base  of  the  Cerebrum. 
The  base  of  the  cerebrum  is  divided  on  each  side  into  two  lobes,  an  anterior  and  a 
posterior,  separated  by  the  fissure  of  Sylvius,  j 

The  Fissure  of  Sylvius. 

This  is  a  fissure  of  considerable  size  (grande  scissure  interlobulaire,  Chauss.),  which 
commences  at  the  corresponding  anterior  extremity  of  the  great  transverse  fissure,  with 
which  it  forms  an  obtuse  angle.  At  the  point  where  they  meet  is  found  a  white  sub- 
stance,t  perforated  with  large  openings  for  bloodvessels  ;  this  Vicq  d'Azyr  has  named 
the  anterior  perforated  substance  ;  it  is  the  locus  perforatus  anterior  (h). 

The  fissure  of  Sylvius  (y,  fig.  276)  is  directed  outward,  and  describes  a  slight  curve, 
having  its  convexity  turned  forward  :  it  corresponds  to  the  posterior  border  of  the  lesser 
wings  of  the  sphenoid  bone,  which  are  received  into  it. 

The  fissure  of  Sylvius  cannot  be  properly  examined  until  both  the  arachnoid  and  pia 
mater  have  been  removed.  It  is  then  found  to  be  very  deep  ;  it  is  seen  that  the  middle 
cerebral  artery  runs  along  the  bottom  of  it,  that  the  pia  mater  lines  it  throughout,  and 
that  it  soon  divides  into  two  branches,  of  which  the  anterior  is  the  smaller,  and  contin- 
ues in  the  original  course  of  the  fissure  ;  while  the  posterior,  which  is  of  much  greater 
extent,  passes  upward  and  backward,  along  the  convex  surface  of  the  hemisphere,  and 
terminates  after  proceeding  a  variable  distance  ;  the  interval  between  these  two  second- 
ary furrows  is  occupied  by  a  sort  of  island  (insula,  Reil),  which  might  be  called  the  lobule 
of  the  fissure  of  Sylvius,  or  the  lobule  of  the  corpus  striatum. 

This  lobule  is  of  a  triangular  form,  having  its  base  directed  upward  and  its  apex  down- 
ward ;  it  is  marked  by  certain  small  superficial  convolutions,  which  radiate  from  below 
upward.  It  will  be  found  immediately  that  this  lobule  corresponds  to  and  is  moulded 
upon  the  corpus  striatum,  which  is  sometimes  so  large  as  to  push  the  lobule  beyond  the 
fissure,  so  that  it  reaches  the  surface  of  the  brain,  and  appears  to  belong  to  the  ante- 
rior lobe. 

The  Anterior  and  Posterior  Lobes  of  the  Cerebrum. 

Several  anatomists  describe  three  lobes  in  each  hemisphere  upon  the  base  of  the  brain, 

*  Cushion,  thick  border. 

t  [Three,  according  to  other  anatomists:  an  anterior  (a, Jig.  276),  a  middle  (e),  and  a  posterior  (6)  ;  the 
anterior  separated  from  the  middle  by  the  fissure  of  Sylvius  (y),  the  posterior  resting-  ou  the  cerebellum,  or, 
rather,  on  the  tentorium.]  "  I  CLight  gray.] 


732  NEUKOLOGT. 

namely,  an  anterior  (a),  a  middle  (c),  and  a  posterior  (i) ;  but  there  are  only  two  :  an  ante 
rior  (a),  which  rests  upon  the  orbital  plate  of  the  frontal  bone,  is  moulded  upon  its  irregu- 
larities, and  is  received  into  the  concavity  of  that  bone  ;  and  a  posterior  (c  b),  which  rests 
upon  the  corresponding  spheno-temporal  fossa  and  the  tentorium  cerebelli.  The  an- 
terior third  of  this  posterior  lobe,  or  the  portion  which  corresponds  to  the  spheno-tem- 
poral fossa,  is  convex,  and  projects  from  six  to  nine  lines  below  the  level  of  the  inferior 
surface  of  the  anterior  lobe.  The  posterior  two  thirds  are  slightly  concave  ;  they  corre- 
spond to  the  tentorium  cerebelli,  and  are  placed  upon  the  same  level  as  the  anterior  lobe. 
The  convex  sphenoidal  portion  of  the  posterior  lobe  forms  what  is  generally  called  the 
middle  lobe,  and  the  posterior,  or  cerebellar  portion,  what  is  then  named  the  posterior  lobe. 
I  believe  that  it  is  useful,  in  many  respects,  to  apply  the  terms  frontal  horn  (cornu  fron- 
tale)  to  the  anterior  extremity  of  the  cerebrum,  which  is  received  into  the  concavity  of 
the  frontal  bone,  sphenoidal  horn  to  the  anterior  extremity  of  the  posterior  lobe,  and  oc- 
cipital horn  to  the  posterior  extremity  of  the  same  lobe. 

The  Convolutions  and  Anfractuosities  of  the  Cerebrum. 

The  entire  surface  of  the  cerebrum  is  marked  by  a  great  number  of  deep,  winding  fur- 
rows, which  divide  it  into  as  many  oblong  eminences,  turned  in  different  directions,  and 
themselves  subdivided  by  secondary  furrows.  These  eminences  have  some  resemblance 
to  the  convolutions  of  the  small  intestine,  and  have  been  named,  on  this  account,  convo- 
lutions, gyri,  meandri,  processus  enteroidei.  The  furrows  by  which  they  are  separated 
are  called  anfracluosities  or  sulci. 

A  more  accurate  notion  of  the  general  character  of  these  convolutions  and  anfractu- 
osities  may  be  obtained  by  supposing  a  bladder  to  be  expanded  round  a  compact  central 
mass,  at  a  certain  distance  from  it,  and  in  this  condition  too  large  to  be  contained  with- 
in the  cranium ;  and  then,  that  by  means  of  threads  proceeding  from  different  points  of 
the  centre,  the  corresponding  parts  of  the  bladder  are  drawn  inward,  so  that  it  is  folded 
upon  itself,  and  can  now  be  contained  within  the  cranial  cavity.  The  various  winding 
folds  and  furrows  produced  in  the  walls  of  the  bladder  by  drawing  them  from  above  and 
from  all  sides  towards  the  centre,  will  give  some  idea  of  the  arrangement  of  the  surface 
of  the  cerebrum. 

Some  of  the  convolutions  and  anfractuosities  are  constant,  because  their  forms  are  de- 
termined by  those  of  the  central  mass  ;  others  are  subject  to  variety,  and  seem  to  de- 
pend upon  no  determinate  cause  :  these  varieties  occur  not  only  in  different  brains,  but 
also  in  the  two  hemispheres  of  the  same  brain.  In  this  respect  the  human  brain  differs 
from  that  of  the  lower  animals,  in  which  the  cerebral  convolutions  present  much  less 
variety,  though  they  are  not  so  constant  as  Vicq  d'Azyr  has  stated. 

The  human  brain  is  distinguished  from  the  brains  of  the  lower  animals,  not  only  by 
its  size  and  weight,  but  also  by  the  number  and  size  of  its  convolutions.  Tiedemann 
has  given  excellent  representations  of  the  progressive  diminution  of  the  cerebral  convo- 
lutions (which  is  accompanied  by  a  diminution  of  the  cerebellum)  from  the  apes  to  the 
rodentia  and  edentata.*  In  the  human  subject,  as  in  the  series  of  lower  animals,  the 
development  of  the  convolutions  has  always  appeared  to  me  to  be  directly  proportioned 
to  the  development  of  the  entire  brain. 

In  this  point  of  view,  as  in  many  others,  the  human  foetus  presents  a  similar  structure 
to  that  found  in  the  lower  animals.  The  furrows  or  anfractuosities  in  the  brain  of  the 
human  foetus  at  the  fifth  month  are  neither  deeper  nor  more  numerous  than  those  in  the 
brain  of  the  rabbit ;  and  it  is  important  to  study  these  primitive  furrows,  because  they 
correspond  to  certain  anfractuosities  which  ultimately  regulate  the  whole  system  of  con- 
volutions. Thus,  at  the  fifth  month,  the  great  anfractuosity,  which  is  called  the  fissure 
of  Sylvius,  exists,  but  its  borders  are  apart  from  each  other ;  the  islantl  of  Reil,  or  the 
lobule  of  the  corpus  striatum,  is  found  upon  the  surface  of  the  brain,  and  there  is  a  lon- 
gitudinal furrow  at  the  lower  and  back  part  of  the  internal  surface  of  each  hemisphere  , 
it  corresponds  to  the  occipital  prolongation  or  posterior  cornu  of  the  lateral  ventricle  ; 
there  is  also  a  furrow  above  the  corpus  callosum  ;  and,  lastly,  the  furrow  of  the  olfactory 
nerve  is  visible.  At  birth,  all  the  convolutions  exist,  but  they  are  not  completely  devel- 
oped until  about  the  age  of  six  or  seven  years. 

It  is  impossible  to  determine  the  number  of  the  convolutions,  for  they  have  no  appre- 
ciable limits  ;  and  although  some  of  them  end  between  two  adjacent  ones,  it  is  easy  to 
see  that  this  termination  is  merely  apparent,  and  that  near  the  point  where  it  seems  to 
take  place,  the  convolution  is  continued  into  another  without  any  line  of  demarcation. 
The  ancient  comparison,  therefore,  between  the  convolutions  of  the  brain  and  those  of 
the  intestines,  not  only  applies  to  their  direction,  but  also  to  their  continuity. 

There  are  several  orders  of  convolutions.  In  fact,  simple  convolutions  are  seen  to  be 
divided,  excavated,  and  furrowed,  more  or  less  deeply  ;  but  there  are  no  regular  and  con 
secutive  subdivisions,  as  in  the  laminae  of  the  cerebellum.     Vertical  sections  made  in 

*  [See  also  Leuret's  figures  in  the  work  already  referred  to,  in  which  will  be  found  a  comparative  view  of 
the  niunber  and  arrangen^nt  of  the  convolutions  of  the  bnun  in  man  and  mammalia.] 


CONVOLUTIONS    AND    ANPEACTD08ITIE3    OF   THE   BRAIN.  73S 

different  directions  will  show  the  arrangement  of  the  convolutions  much  better  than  the 
most  careful  observations  of  the  external  surface  of  the  brain. 

Each  convolution  presents  to  our  notice  two  surfaces,  a  base  or  adherent  border,  and  a 
free  border.  The  surfaces  of  the  corresponding  convolutions  are  moulded  upon  each 
other,  and  separated  by  a  duplicature  of  the  pia  mater. 

The  base  or  adherent  border  of  each  convolution  is  continuous  with  the  central  portion 
of  the  hemisphere  (see  section,  ^^.  277). 

The  free  border  is  slightly  rounded,  so  that  between  any  two  contiguous  convolutions 
there  is  a  small  groove,  which  is  very  distinct  in  cases  of  purulent  infiltrations  or  depo- 
sitions of  lymph  in  the  sub-arachnoid  cellular  tissue. 

At  the  points  where  these  convolutions  meet,  a  triangular  depression  is  observed. 
These  spaces  are  small  in  the  natural  state,  but  become  very  evident  in  cases  of  atrophy 
of  the  convolutions. 

The  free  border  of  some  convolutions  is  frequently  marked  by  an  oblong  depression  or 
groove,  varying  in  depth  and  extent,  and  following  the  direction  of  the  convolutions ; 
these  depressions  are  sometimes  sharp,  and  radiate  into  three  or  four  branches  ;  at  other 
times  they  are  superficial,  or,  lastly,  deep  and  narrow.  The  arteries  and  veins  which 
pass  over  the  free  borders  of  the  convolutions  form  grooves  upon  them  of  various  depths. 

The  free  borders  of  most  of  the  convolutions  generally  reach  the  surface  of  the  brain ; 
but  besides  the  secondary  convolutions,  several  of  which  remain  concealed  throughout 
their  whole  length,  between  two  adjacent  convolutions,  there  are  some  principal  convolu- 
tions, which  descend  at  one  of  their  extremities  between  two  adjacent  convolutions  ;  and 
there  are  others,  again,  which  are  depressed  at  one  or  at  several  points  of  their  extent. 

The  depth  of  the  convolutions  varies  from  ten  to  fourteen  lines,  but  it  is  extremely 
variable  in  different  individuals  ;  moreover,  there  are  perhaps  not  two  convolutions,  nor 
two  parts  of  the  same  convolution,  which  correspond  in  thickness  in  the  same  brain  ; 
some  are  considerably  swollen,  while  others  are  narrow  ;  there  is  almost  always  an  en- 
largement at  the  point  where  two  convolutions  become  continuous.  Eustachius  and 
Vieussens  have  erred,  then,  in  representing  all  the  convolutions  as  perfectly  similar. 

It  would  be  undoubtedly  curious  to  describe  minutely  all  the  convolutions.  Vesalius, 
who  appears  to  have  entertained  the  idea  of  so  doing,  likened  the  appearance  of  the  sur- 
face of  the  brain  to  those  irregular  forms  which  are  traced  by  unskilful  painters  in  de- 
lineating clouds.  Vicq  d'Azyr  made  an  unsuccessful  attempt  to  elucidate  this  subject ; 
Gall  and  Spurzheim,  who  were  interested  in  giving  a  minute  description  of  each  convo- 
lution, abandoned  the  task  ;  I  have  myself  attempted,  and  so  has  Rolando,  to  describe 
and  name  some  of  them.  The  description,  however,  to  be  understood,  would  require 
the  assistance  of  figures  ;  I  shall,  therefore,  content  myself  with  noticing,  in  this  place, 
the  most  important  convolutions  upon  the  internal  surface,  upon  the  inferior  surface,  and 
upon  the  external  surface,  or  convexity  of  each  hemisphere. 

Convolutions  and  Anfractuosities  upon  the  Internal  Surface. 

The  convolution  of  the  corpus  callosum  is  one  which  predominates  over  all  those  of  the 
internal  surface  of  the  hemisphere  ;  it  is  that  which  embraces  the  corpus  callosum,  and 
hence  its  name.  It  commences  in  front,  below  the  reflected  extremity  of  that  body,  to 
which  it  adheres,  passes  forward  and  upward,  turns  round  its  anterior  extremity,  then 
extends  backward,  and  having  reached  beneath  the  posterior  extremity  of  the  corpus 
callosum,  continues  its  course,  and  is  arranged,  in  a  manner  to  be  presently  described, 
upon  the  lower  surface  of  the  cerebrum. 

It  is  narrow  at  its  anterior  extremity,  which  Rolando  regards  as  the  principal  root  of 
the  olfactory  nerve ;  it  increases  in  size  as  it  proceeds,  and  opposite  the  middle  of  the 
corpus  callosum  it  is  elevated  like  a  crest,  becomes  much  broader,  and  is  marked  by  sev- 
eral furrows,  of  which  some  are  superficial  and  others  deep.  Tlie  circumference  of  this 
broad  crest  is  divided  into  several  branches,  which  become  continuous  either  with  the 
superior  convolutions  of  the  convex  surface,  or  with  the  posterior  and  superior  convolu- 
tions of  the  internal  surface  of  the  hemisphere.  Vicq  d'Azyr  first  pointed  out  this  crest 
of  the  convolution  of  the  corpus  callosum,  and  it  was  named  by  Rolando  processo  enter- 
oido  cristato. 

The  internal  convolution  of  the  anterior  lobe  is  eccentric  in  reference  to  the  one  just  de- 
scribed, upon  which  it  is  moulded,  a  deep  anfractuosity  intervening  between  them.  It  is 
very  large  at  its  origin  in  front  of  the  fissure  of  Sylvius  ;  it  forms  the  internal  part  of  the 
anterior  lobe  of  the  cerebrum,  and  having  arrived  in  front  of  the  crest  of  the  convolution  of 
the  corpus  callosum,  it  passes  upward,  and  becomes  continuous  with  the  convolutions 
of  the  convex  surface  of  the  hemisphere. 

This  convolution  is  divided  throughout  its  entire  extent  by  a  secondary  anfractuosity, 
which  is  at  first  straight,  and  then  sinuous. 

Convolutions  and  Anfractuosities  of  the  Digital  Cavity. 
A  very  deep  longitudinal  furrow,  which  corresponds  to  the  digital  cavity  of  the  lateral 
ventricle,  and,  like  it,  constantly  exists,  extends  from  the  convolution  of  the  corpus  cal- 


734  NEUROLOGY. 

losum,  near  the  posterior  extremity  of  that  body,  directly  backward  along  the  posterior 
lobe  of  the  brain,  which  it  divides  into  a  superior  and  inferior  portion.  This  anfractu- 
osity  of  the  digital  cavity  forms  a  division  between  the  internal  and  inferior  surfaces  of  the 
hemisphere. 

Ti\e  convolutions  of  the  digital  cavity  are  the  two  longitudinal  and  tortuous  convolu- 
tions which  bound  this  anfractuosity ;  the  upper  convolution  belongs  to  the  internal  sur- 
face of  the  hemisphere,  while  the  lower  one  forms  part  of  the  inferior  surface. 

Convolutions  and  Anfractuositics  upon  the  Inferior  Surface. 

The  great  anfractuosity,  called  the  fissure  of  Sylvius,  divides  the  convolutions  of  the 
inferior  surface  into  those  of  the  anterior  and  those  of  the  middle  and  posterior  lobe. 

The  convolutions  of  the  anterior  lobe  constantly  found  are,  the  two  small,  straight,  longi- 
tudinal convolutions  which  bound  the  groove  of  the  olfactory  nerve  {I,  fig.  276),  and  the 
flexuous  convolution,  which  extends  obUquely  forward  and  outward,  along  the  border  of 
the  fissure  of  Sylvius,  and  is  continuous  behind  with  the  external  straight  convolution 
of  the  olfactory  nerve. 

The  small  convolutions  and  intervening  anfractuosities  are  very  irregular,  and  differ 
in  different  individuals,  and  even  on  the  two  sides  in  the  same  individual ;  into  the  de- 
pressions formed  between  these  convolutions  are  received  the  prominent  ridges  seen 
upon  the  orbital  plate  of  the  frontal  bone. 

The  Convolutions  of  the  {Middle  and)  Posterior  Lobe. — The  convolution  which  runs  along 
the  great  transverse  fissure  is  the  continuation  of  the  convolution  of  the  corpus  callosum, 
and  terminates  in  front  by  an  unciform  enlargement,  which  corresponds  to  the  dilated 
extremity  of  the  comu  Ammonis  ;  it  forms  the  outer  boundary  of  the  great  transverse 
fissure.  The  convolution  of  the  corpus  callosum  and  its  continuation,  viz.,  that  of  the 
transverse  fissure,  represent  an  ellipse,  which  is  broken  only  at  the  fissure  of  Sylvius. 

On  the  outer  side  of  this  convolution  is  a  longitudinal  anfractuosity,  which  corresponds 
to  the  lower  wall  of  the  inferior  comu  of  the  lateral  ventricle. 

This  anfractuosity  is  bounded  by  certain  longitudinal  convolutions,  all  of  which  pro- 
ceed from  the  convolution  of  the  transverse  fissure,  and  are  remarkable  for  their  size 
and  windings. 

The  most  internal  of  these  convolutions  forms  the  lower  boundary  of  the  anfractuosity 
which  I  have  said  corresponds  to  the  posterior  comu  of  the  lateral  ventricle. 

From  the  anterior  part  of  the  convolution  of  the  transverse  fissure  some  extremely 
flexuous  convolutions  proceed  from  behind  forward,  assist  in  forming  the  sphenoidal 
horn  (point  of  the  middle  lobe),  and  become  continuous  with  the  convolutions  of  the  ex- 
ternal face  of  the  hemisphere. 

Convolutions  and  Anfractuosities  of  the  Convex  Surface. 

The  convolutions  upon  the  convex  surface  of  the  hemisphere  are,  undoubtedly,  the 
most  complicated  ;  on  separating  the  borders  of  the  fissure  of  Sylvius,  within  which  the 
island  of  Reil  is  contained,  it  is  seen  that  the  fissure  is  triangular,  and  presents  three 
sides  :  an  inferior  border,  formed  by  the  external  convolution  of  the  anterior  lobe  of  the 
cerebrum  ;  a  posterior  border,  directed  very  obliquely  upward  and  backward,  which  ap- 
pears to  receive  all  the  occipital  convolutions,  and  consists  of  a  very  tortuous  convolu- 
tion ;  and  a  superior  border,  also  consisting  of  a  very  winding  convolution,  in  which  the 
majority  of  the  superior  convolutions  terminate. 

The  convolutions  upon  the  convex  surface  of  the  brain  may  be  divided  into  the  frontal, 
the  parietal,  and  the  occipital. 

The  frontal  convolutions  are  three  or  four  in  number,  and  are  directed  from  before  back- 
ward. The  parietal  convolutions  are  three  in  number  ;  they  pass  in  a  serpentine  direction 
from  within  outward,  and  become  continuous  with  the  convolution  which  forms  the  su- 
perior border  of  the  fissure  of  Sylvius.  The  occipital  convolutions  are  directed  from  before 
backward,  and  proceed  either  from  the  posterior  parietal  convolution,  or  from  the  pos- 
terior border  of  the  fissure  of  Sylvius. 

The  occipital  convolutions  are  the  narrowest  anil  the  most  sinuous  of  all,  so  that  the 
sides  of  the  sinuosities  of  each  convolution  are  in  mutual  contact  in  the  greatest  part  of 
their  extent,  and  touch  the  adjacent  convolutions  only  at  the  points  at  which  they  are 
bent.* 

The  frontal  convolutions  are  also  very  flexuous,  and  have  similar  characters  to  the 
occipital,  but  not  so  distinctly  marked.  They  are  larger  than  the  occipital  convolutions, 
but  smaller  than  the  parietal,  which  are,  moreover,  less  tortuous  than  either  of  the  others. 

The  unusual  details  with  which  I  have  described  the  convolutions  can  only  be  justified 
by  the  importance  which  has  recently  been  attached  to  them.  In  the  preceding  descrip- 
tion the  following  points  have  been  noticed  :  Their  general  disposition,  their  windings, 
and  their  mutual  adaptation  ;  their  continuity,  and  the  impossibility  of  drawing  any  pre- 
cise limits  between  them  ;  their  general  configuration,  according  to  a  common  type,  and 
the  want  of  uniformity  in  their  details,  not  only  in  different  brains,  but  also  in  the  oppo- 

*  In  senile  atrophy,  the  occipital  convolutions  are  chiefly  affected. 


FUNCTIONS   OF    THE  CONVOLUTIONS   AND  ANFEACTUOSITIES.         735 

site  hemispheres  of  the  same  brain  ;  their  variable  dimensions  in  different  individuals, 
both  in  respect  of  depth  and  width,  these  being  always  directly  proportioned  to  the  size 
of  the  cerebral  hemisphere  :  the  individual  differences  both  in  the  size  of  the  brain  and 
in  that  of  the  convolutions  are  very  great.*  We  have  also  seen  that  the  internal  surface 
of  the  cranium  is  exactly  moulded  upon  the  surface  of  the  brain,  the  digital  impressions 
in  the  cranial  bones  corresponding  to  the  convolutions,  and  the  ridges  or  eminences  to 
the  small  spaces  intervening  between  the  free  borders  of  the  convolutions. 

Functions  of  the  Convolutions  and  A  nfractuositics. 
'    The  convolutions  and  anfractuosities  render  the  surface  of  the  brain  of  much  greater 
extent  than  it  would  otherwise  have  been.     According  to  Vesalius,  they  are  of  use  in 
multiplying  the  surface,  through  which  the  bloodvessels  carry  nutritious  matter  into  the 
interior  of  the  organ,  t 

The  opinion  that  the  anfractuosities  and  convolutions  are  intended  to  increase  the 
surface  has  been  lately  revived ;  but  the  supposed  object  of  this  increase  is  very  differ- 
ent from  that  stated  by  Vesahus  :  thus,  it  has  been  agreed  that,  as  there  is  an  undoubt- 
ed analogy  between  electrical  phenomena  and  those  manifested  by  the  nervous  system, 
and  as  electrical  phenomena  are  developed,  not  in  proportion  to  the  quantity  of  matter 
concerned,  but  in  proportion  to  the  extent  of  surface,  so  the  energy  of  the  brain's  action 
may  be  in  a  direct  ratio  with  the  extent  of  its  surface.  In  support  of  this  opinion,  the 
phenomena  of  arachnitis  are  quoted,  in  which  disease  delirium  more  frequently  occurs 
than  in  inflammation  of  the  cerebral  substance  itself  Allusion  is  also  made  to  the  folds 
observed  in  the  retinae  of  birds,  which  greatly  increase  the  intensity  of  vision  :  M.  Des- 
moulins,  who  is  a  principal  supporter  of  this  theory  regarding  the  use  of  the  convolu- 
tions, states  that  he  has  observed  these  folds  to  disappear  in  birds  which  had  been  kept 
in  the  dark,  in  the  same  way  that  the  cerebral  convolutions  become  atrophied,  either 
from  the  continued  absence  of  all  cerebral  excitement,  or  from  any  other  cause  of  intel- 
lectual weakness. 

The  anatomists  and  philosophers  of  antiquity,  considering  that  the  convolutions  were 
more  highly  developed  in  man  than  in  the  lower  animals,  concluded  that  tlie  intellectueil 
superiority  of  the  former  was  owing  to  this  circumstance.  Such  was  the  opinion  of 
Erasistratus,  facetiously  refuted  by  Galen4 

Gall  and  Spurzheim  have  recently  revived  this  old  opinion,  and  assuming,  with  some 
philosophers,  the  existence  of  a  plurality  of  mental  functions,  they  have  arrived  at  the 
conclusion  that  there  is  also  a  plurality  of  material  instruments  or  organs,  by  which 
those  functions  are  performed.  These  material  organs  are  supposed  by  them  to  be  the 
convolutions,  upon  which  they  accordingly  placed  numbers  corresponding  to  the  differ- 
ent mental  faculties  admitted  by  their  philosophy :  the  difficulty  was  to  settle  on  the 
number  of  primitive  mental  faculties  and  their  corresponding  organs.  According  to  Gall 
and  Spurzheim,  the  highest  intellectual  faculties  of  man  are  seated  in  the  anterior  lobes 
of  the  cerebrum. 

On  the  other  hand,  from  an  examination  of  the  brains  of  fifty  insane  patients,  M.  Neu- 
mann has  been  led  to  think  that  the  occipital  portion  of  the  cerebrum  is  the  seat  of  in- 
telligence :  this  opinion  derives  some  support  from  a  fact  which  I  have  myself  often  ob- 
served, viz.,  that  atrophy  of  the  brain  of  old  persons  in  insanity  affects  the  occipital 
more  than  the  frontal  convolutions  ;  and  also  by  the  fact,  that,  as  we  descend  in  the  ani- 
mal series,  the  posterior  part  of  the  brain  is  observed  to  be  the  first  to  diminish,  and 
then  entirely  to  disappear. 

It  is  unfortunate  for  the  system  of  Gall  that  the  convolntions  form  a  continuous  whole, 
and  are  not  separated  into  distinct  organs  ;  and  it  is  also  unfortunate  that,  upon  the  base 
of  the  cerebrum,  and  upon  the  internzil  surface  of  each  hemisphere,  there  are  convolu- 
tions as  distinctly  marked  as  those  upon  the  convex  surface  ;  and  yet,  in  the  system  of 
Gall,  the  convolutions  upon  the  base  and  internal  surface  of  the  hemispheres  have  been, 
so  to  speak,  disinherited ;  for  all  the  mental  faculties  have  been  located  by  him  in  the 
convolutions  of  the  convex  surface. 

The  Internal  Structure  of  the  Cerebrum. 

In  order  to  make  as  complete  an  examination  of  the  internal  conformation  of  the  brain 
as  is  possible  in  the  actual  state  of  science,  it  should  be  prosecuted  by  means  of  sections 

*  Comparative  anatomy  fully  confirms  this  fact :  the  convolutions  of  a  small  hemisphere  are  very  sh'ghtly 
developed,  and  they  do  not  exist  at  all  when  the  hemispheres  are  very  thin,  as  in  birds. 

+  The  substance  of  the  brain,  says  Vesalius,  is  not  firm  enough  for  the  arteries  and  veins  to  traverse  it  with 
impunity  ;  on  the  other  hand,  it  is  so  thick  that  bloodvessels  distributed  over  its  surface  would  not  have  been 
sufficient  to  nourish  the  entire  mass  ;  and,  therefore,  nature  has  provided  certain  deep  and  winding  furrows 
upon  the  brain,  into  which  the  pia  mater  can  penetrate,  so  as  to  convey  to  the  deep-seated  parts  the  materials 
for  their  nutrition  ;  for  the  same  Teason,  the  cerebellum  has  been  divided  into  laminse  and  lamella.  Vesalius 
even  states  that  the  division  of  the  cerebrum  into  two  hemispheres  is  for  no  other  purpose  (lib.  vii.,  cap.  4, 
p.  542). 

t  "  Quum  asini  etiam  admodum  multipliciter  cerebrum  habent  complexnra  quod  deccret,  quantum  ad  mo- 
rum  ruditatem  attinet,  omnifariam  simplex  et  minime  varium  nancisi  cwebrum."  If  this  theory  be  true,  says 
Galeu,  the  ass  ought  to  have  a  brain  with  a  smooth  surface,  and  no  convolutions  ;  but  it  has  numerous  and 
deep  convolutions  :  the  intellectual  faculties,  therefore,  are  independent  of  the  convolutions.  The  conclusion 
is  not  obviously  contained  in  the  premises. 


736 


NEUROLOGY. 


in  different  directions ;  by  tearing  the  brain,  and  by  acting  upon  it  with  streams  ol  wa- 
ter ;  and  liy  dissecting  brains  that  have  been  hardened  by  alcohol,  or  by  being  boiled  in 
oil  or  in  a  strong  solution  of  salt. 

Examination  of  the  Internal  Structure  of  the  Brain  by  Sections. 

This  mode  of  examining  the  brain  was  the  one  employed  by  Galen  ;  it  was  revived  by 
Vicq  d'Azyr,  and  is  now  generally  adopted. 

By  means  of  these  different  sections  it  is  easy  to  study  the  internal  conformation  of 
the  brain  in  its  principal  details.  The  other  methods  are  more  especially  adapted  for 
determining  the  connexions  of  the  several  parts  of  the  cerebrum  with  each  other,  or 
with  the  other  portions  of  the  cerebro-spinal  axis.  I  shall  commence  by  an  examina- 
tion of  horizontal  sections  of  the  brain.* 

Horizontal  Sections  of  the  Brain. 
On  making  an  incision  into  the  brain,  this  organ  is  found  to  consist  of  two  substances . 
a  gray  cineritious  or  cortical  substance,  and  a  ichite  or  medullary  substance,  which  is  sur- 
rounded on  all  sides  by  the  gray.t 

First  Section. — A  horizontal  section,  made  so  as  to  remove  the  wpper  half  of  the  supe- 
rior convolutions  of  the  cerebrum,  shows  that  each  convolution  consists  of  a  central  white 
portion,  surrounded  on  all  sides  with  a  layer  of  gray  substance  ;  that  the  gray  substance 
is  accurately  moulded  upon  the  white,  the  form  of  which  determines  that  of  the  corre- 
sponding convolution  ;  that  the  thickness  of  the  gray  matter  varies  from  half  a  line  to  a 
line  and  a  half;  and  that  it  is  far  from  being  uniform,  either  in  the  same  or  in  different 
convolutions.  In  judging  of  the  thickness,  it  is  important  to  have  regard  to  the  direc- 
tion of  the  section  ;  for  it  is  easy  to  understand  that  an  oblique  section  of  the  gray  mat- 
ter will  give  a  very  different  result  from  one  made  perpendicularly.  The  section  de- 
scribed above  also  shows  that  the  convolutions  are  continuous  with  each  other,  and  it 
enables  us  to  comprehend  their  irregular,  complex,  and  sinuous  arrangement  better  than 
could  be  done  without  cutting  into  the  brain. 

The  relative  proporiion  of  the  gray  and  white  substances  in  each  convolution  may  be 
determined  approximately  by  macerating  a  brain  for  some  days  ,  the  gray  substance  be- 
ing softer  and  more  readily  decomposed,  is  thus  converted  into  pulp,  and  may  be  easily 
removed.  The  convolutions  being  thus  reduced  to  the  white  substance  only,  appear 
like  short,  white  lamellas,  arising  from  different  points  of  the  surface  of  the  central  me- 
dullary mass.     I  estimate  the  gray  matter  at  about  five  sixths  of  each  convolution. 

Second  Section. — A  horizontal  section  made  beneath  the  base  of  the  convolutions  of  the 
convex  surface  of  the  hemispheres  presents  an  appearance  like  that  of  a  geographical 

chart  of  a  deeply  and  irregularly  in- 
dented coast ;  an  appearance  which 
cannot  be  described  without  fig- 
ures. It  consists  of  a  central  mass 
of  medullary  substance,  which  is 
narrowed  like  an  isthmus  behind: 
extending  from  this  central  mass 
are  certain  prolongations,  which 
may  be  divided  into  several  orders, 
and  which  are  themselves  subdivi- 
ded, so  as  to  form  the  medullary 
centre  of  each  convolution. 

Third  Section. — A  horizontal  sec- 
tion, made  on  a  level  with,  or,  rath- 
er, just  above,  the  corpus  callosum, 
displays  a  great  medullary  centre  in 
each  hemisphere  (centre  medullaire 
hemispheral ;  centrum  ovale  minus ; 
acb,  acb,  Jig.  277). 

The  two  centres  of  the  opposite 
sides,  together  with  the  corpus  cal- 
losum {d  d),  form  the  centrum  ovale 
of  Vieussens. 

The  centrum  ovale  of  Vieussens  i« 
contracted  in  the  middle  line,  where 
it  is  formed  by  the  corpus  callosum, 
but  is  much  larger  in  each  hemi- 
sphere. The  anfractuosities  by 
which  the  circumference  of  this 
section  is  indented  are  seen  to  be 
deeper  on  the  outside  and  behind,  than  on  the  inside  and  in  front. 

*  The  sections  should  be  made  with  a  very  sharp  instrument,  a  razor,  for  example.  t  See  note,  p.  701. 


THE    CORPUS    CALLOSUM.  737 

By  the  three  horizontal  sections  just  described,  it  is  shown  that  eacn  convolution  (/  f 
f)  consists  of  a  white,  central  portion,  surrounded  by  a  thick  layer  of  gray  substance, 
having  a  precisely  similar  shape  ;  that  it  is  the  gray  matter  which  predominates  in  the 
convolutions  ;  that  the  central  portions  of  all  the  convolutions  are  continuous  with  each 
other,  and  form  the  most  complicated  windings  ;  that  they  all  rest  upon  a  hemispherical 
central  mass,  which  becomes  larger  and  larger  towards  the  corpus  callosum,  on  a  level 
with  which  it  attains  its  greatest  dimensions ;  that  the  centrum  ovale  of  Vieussens, 
which,  however,  is  not  oval,  represents  the  largest  medullary  surface  of  the  brain,  and 
might  be  regarded  as  a  centre,  from  which  all  the  radiations  that  enter  the  convolutions 
are  given  off  in  one  direction,  and,  in  the  other,  all  those  which  establish  connexions  be- 
tween the  brain  and  the  other  parts  of  the  cerebro-spinal  axis  ;  lastly,  that  the  centrum 
ov£ile  and  the  convolutions  are  always  developed  in  a  corresponding  ratio. 

The  Corpus  Callosum. 

If,  when  the  brain  is  resting  upon  its  base,  the  two  hemispheres  be  drawn  asunder,  a 
transverse  white  band  is  seen  at  the  bottom  of  the  longitudinal  fissure,  extending  from 
one  hemisphere  to  the  other,  and  connecting  them  together,  and  forming  their  commis- 
sure :  this  band  is  the  corpus  callosum*  (mesolobe,  Chaussier ;  commissura  cerebri  mag- 
na, maxima,  Rcil,  Soemmering,  d  d).  On  removing  the  upper  part  of  the  two  hemi- 
spheres by  a  horizontal  section  made  about  a  line  or  two  above  the  corpus  callosum,  it 
is  seen  that  each  hemisphere  encroaches  upon  the  corpus  callosum,  and  overhangs  it 
without  adhering  to  it :  the  interval  between  the  hemisphere  and  the  corpus  callosum 
has  been  improperly  termed  the  ventricle  of  the  corpus  callosum.  But  there  is  no  cavity 
here,  nor  is  there  a  smooth  exhalant  and  absorbing  surface  ;  it  is  merely  an  anfractuos- 
ity,  separating  the  corpus  callosum  from  the  convolutions,  and  lined  by  the  pia  mater, 
like  all  other  anfractuosities.  On  continuing  to  remove  successive  portions  of  the  hem- 
isphere, it  is  found  that  it  can  be  separated  without  any  laceration  from  the  corpus  cal- 
losum, much  farther  than  the  point  at  which  the  pia  mater  is  reflected,  and  that  the 
hemisphere  and  corpus  callosum  are  simply  in-  contact  with  each  other  ;  the  fibres  of 
the  hemisphere  are  seen  to  be  longitudinal,  while  those  of  the  corpus  callosum  are 
transverse. 

From  this  observation,  it  follows  that  the  middle  or  free  portion  of  the  corpus  callo- 
sum (shown  in^^.  277)  is  but  a  small  part  of  that  body. 

The  corpus  caUosum  reaches  much  nearer  to  the  anterior  (x)  than  to  the  posterior  (y) 
extremity  of  the  cerebrum,  being  an  inch  and  some  lines  distant  from  the  former,  and 
from  two  to  three  inches  from  the  latter. 

Its  length  is  about  three  inches  and  a  half;  it  is  broader  behind  than  in  front ;  its  breadth 
behind  varies  from  eight  to  ten  lines,  if  we  include  the  part  which  is  covered  by  the  hem- 
ispheres :  its  thickness,  which  can  be  properly  shown  only  upon  a  vertical  section  (see 
Jig.  282),  along  the  middle  line,  is  not  uniform  throughout ;  its  thickest  part  is  at  the 
posterior  extremity  (/),  which  is  about  three  lines  thick :  in  front  of  this  extremity  it 
diminishes  abruptly,  and  is  scarcely  a  line  or  a  line  and  a  half  in  thickness  (d) ;  it  then 
^gradually  increases  from  behind  forward,  and  is  about  two  lines  thick  at  its  anterior  ex- 
tremity, opposite  the  point  of  its  reflection  (c). 

Inform  the  corpus  callosum  resembles  an  arch  or  vault,  so  that  it  would  deserve  the 
*name  of  vault  or  fornix  better  than  the»part  usually  so  called. 

Its  vaulted  form  is  distinctly  shown  upon  a  longitudinal  vertical  section  {fig.  282),  and 
at  the  same  time  it  is  seen  that  the  posterior  extremity  of  the  corpus  callosum  is  rolled 
up,  as  it  were,  so  as  to  form  an  enlargement,  while  its  anterior  extremity  is  merely  re- 
flected downward  and  backward,  and  after  its  reflection  becomes  gradually  thinner  as  it 
descends,  and  terminates  in  a  very  delicate  lamella. 

The  corpus  callosum  presents  for  our  consideration  a  superior  and  an  inferior  surface 
*and  two  extremities.  The  superior  surface  is  convex,  and,  as  it  were,  arched  from  be- 
fore backward  {medxdlaris  arcus) ;  it  has  no  raphe  along  the  median  line,  but  presents  in 
that  situation  a  slight  groove  (e,  fig.  277),  depending  on  the  existence  of  two  white  Ion 
gitudinal  tracts,  one  on  each  side  the  middle  line,  which  were  regarded  by  Lancisi  as 
constituting  a  nerve,  the  longitudinal  nerve  of  Lancisi. 

These  tracts  are  subject  to  variations :  thus,  they  are  sometimes  slightly  flexuous, 
and  contiguous  to  each  other,  and  at  other  times  they  unite,  and  then  separate.  Duver- 
ney  has  described  certain  ash-coloured  longitudinal  tracts,  but  their  existence  has  been 
denied  by  most  anatomists. 

The  white  longitudinal  tracts  are  intersected  at  right  angles  by  transverse  fasciculi, 
which  constitute  the  corpus  callosum. 

The  upper  surface  of  the  corpus  callosum  corresponds  to  the  hemispheres  on  each 
side  ;  it  is  free  in  the  middle,  where  it  corresponds  to  the  arteries  of  the  corpus  callosum 
and  to  the  free  margin  of  the  falx,  which  has  appeared  to  me  to  approach  very  closely  to 

*  According  to  Ilaller,  its  name  is  derived  from  its  whiteness,  which  has  been  compared  to  the  colour  of  a 
cicatrix  ;  according  to  others,  it  was  given  on  account  of  the  consistence  of  this  part,  which  has  been  errone- 
uslv  regarded  as  exceeding  that  of  other  parts  of  the  brain 

5  A 


NEUROLOGY. 

the  posterior  extremity  of  this  body,  but  not  to  touch  it,  so  that  it  could  not  occasion 
any  depression  upon  it. 

The  inferior  surface  of  the  corpus  callosum  is  concave,  and  is  free  over  a  greater  extent 
than  the  superior  ;  it  forms  the  upper  wall  or  roof  of  the  lateral  ventricles  (t  i,  fg.  278, 
in  which  figure  only  the  anterior  and  posterior  extremities,  e  and  d,  of  the  corpus  callo- 
sum are  left).*  This  surface  is  covered  by  the  serous  membrane  of  the  ventricles,  and, 
hke  the  superior  surface,  it  is  fasciculated. 

Along  the  median  line  it  corresponds,  in  front,  to  the  septum  lucidum  {t,  figs.  278, 
282),  and  behind  to  the  fornix  (k),  with  which  it  even  seems  to  be  united  at  this  point. 
In  consequence  of  the  somewhat  regular  arrangement  of  the  fibres  constituting  the  two 
posterior  pillars  of  the  fornix  (r  r,  figs.  278,  279),  which  diverge  in  this  situation,  and 
also  of  that  of  the  transverse  fibres  of  the  corpus  callosum,  the  back  part  {s,fig.  279)  of 
the  inferior  surface  of  the  corpus  callosum  has  received  the  names  of  lyra,  corpus  psal- 
loides,  psalterium. 

The  posterior  extremity  of  the  corpus  callosum  (bourrelet,  Reit),  which,  as  we  have  al- 
ready stated,  is  its  thickest  part,  is  slightly  concave  transversely,  but  presents  no  other 
notch,  excepting  the  median  depression,  between  the  longitudinal  tracts. t 

The  anterior  extremity  of  the  corpus  callosum  does  not  terminate  in  an  enlargement,  like 
the  posterior,  but  it  is  reflected,  and  embraces  the  anterior  extremity  of  the  corpus  stri- 
atum :  it  then  passes  downward  and  backward  (e,  fig.  282),  and  terminates  insensibly  in 
front  of  the  anterior  portion  (m)  of  the  floor  of  the  third  ventricle.  Reil  applies  the  term 
knee  (genu)  to  the  point  of  reflection,  and  that  of  beak  (rostrum)  to  the  posterior  and  thin 
extremity  of  the  reflected  portion.  This  reflected  portion  of  the  corpus  callosum  is  seen 
upon  the  base  of  the  brain,  between  the  anterior  lobes  :  the  convolution  of  the  corpus 
callosum  also  accompanies  its  reflected  portion,  and,  instead  of  being  merely  in  contact, 
becomes  continuous  with  it,  so  that  the  gray  matter  rests  immediately  upon  the  corpus 
callosum.  The  longitudinal  tracts  arise  from  the  reflected  portion  of  the  corpus  callo- 
sum ;  and  the  inferior  peduncles  of  the.corpus  callosum  (Vicq  d'Azyr),  already  mention- 
ed, terminate  upon  this  portion. 

The  right  and  left  borders  of  the  corpus  callosum  enter  deeply  into  the  substance  of 
the  hemispheres. 

Beneath  the  corpus  callosum  are  situated,  in  the  median  line,  the  septum  lucidum  (t  t, 
fig.  278),  \h&  fornix  (k),  the  velum  iyiterpositum  (v,fig.  279),  and  the  median  or  third  ven- 
tricle (c  to  x,fig.  280) ;  and  at  the  side,  the  lateral  ventricles  (i  i,fig.  278).  We  shall  pro- 
ceed to  examine  these  different  parts  in  the  above-mentioned  order.  To  obtain  a  good 
idea  of  their  form  and  relations,  it  is  important  to  study  them  upon  two  brains,  one  rest- 
ing upon  its  convex  surface,  and  the  other  upon  its  base. 

The  Septum  Lucidum. 

The  septum  lucidum,  or  transparent  septum,  so  called  because  it  separates  the  lateral 
ventricles  from  each  other  and  is  semi-transparent,  is  situated  in  the  median  line  (sep- 
tum median,  Chauss.).  It  is  very  well  seen  (t,fig.  282)  when  the  corpus  callosum  has 
been  divided  longitudinally  on  each  side  of  the  middle  line.  It  appears  like  a  thin  lami- 
na given  off  from  the  anterior  and  inferior  part  of  the  corpus  callosum,  and  passing  ver- 
tically downward  in  front  of  the  fornix ;  it  is  of  a  triangular  shape,  broad  in  front  and 
narrow  behind  ;  its  lateral  surfaces  constitute  the'  internal  walls  of  the  lateral  ventricles ; 
its  upper  border  is  continuous  with  the  corpus  callosum,  its  posterior  with  the  fornix, 
and  its  inferior  with  the  reflected  portion  of  the  corpus  callosum  in  front,  and  with  the 
inferior  peduncles  of  that  body  farther  back.  Hence  Vicq  d'Azyr  imagined  that  the  sep- 
tum lucidum  was  a  continuation  of  these  peduncles. 

The  septum  lucidum  is  composed  of  two  very  delicate  and  completely  distinct  lamel- 
lae (t  t,  fig.  278),  between  which,  in  front,  a  cavity  is  enclosed,  containing  a  few  drops 
of  a  serous  fluid ;  this  small  cavity  is  called  the  ventricle  of  the  septum,  the  first  ventricle 
{Wenzel),  the  fifth  ventricle  (Cuvier),  and  the  sinus  of  the  median  septum  (Chauss.) ;  it  is 
not  very  unfrequently  the  seat  of  dropsical  effusion.  I  have  found  it  filled  with  blood  in 
several  subjects  after  death  from  apoplexy. 

As  to  whether  this  ventricle  of  the  septum  communicates  with  the  other  ventricles, 
opinions  are  divided.  Tarin  describes  a  small  fissure  opening  between  the  anterior  pil 
lars  of  the  fornix,  but  the  majority  of  anatomists  have  not.  been  able  to  demonstrate  it 
It  appears  to  me  that  the  absence  of  all  communication  is  a  well-ascertained  fact. 

Each  of  these  lamella;  of  the  septum  lucidum  consists  of  a  medullary  layer,  covered 
on  the  outside  by  the  membrane  of  the  corresponding  lateral  ventricle,  and  on  the  inside 
by  the  membrane  of  the  fifth  ventricle.  The  existence  of  this  last-mentioned  membrane 
is  proved  by  the  smooth  appearance  of  the  ventricle,  and  it  may  be  demonstrated  by  re- 

*  The  best  mode  of  examining  the  lower  surface  of  the  corpus  callosum  is  to  view  it  by  opening  the  ventri- 
cles from  the  base  of  the  brain. 

t  One  is  astonished  to  read,  in  Chaussier's  work,  that  the  notch  of  the  posterior  extremity  of  the  corpus 
■  callosum  is  caused  by  the  alternate  movements  of  elevation  and  depression  of  the  brain.    At  each  elevation, 
according  to  him,  this  extremity  of  the  corpus  callosum  strikes  against  the  free  margin  of  the  falx  cerebri  al- 
though that  margin  is  at  some  slight  distance  from  it. 


THE   FORNIX    AND  CORPUS  FIMBRIATUM. 


739 


Fig.  278. 


moving,  in  succession,  layers  from  the  outer  surface  of  the  lamella.    The  gray  matter  of 
the  third  ventricle  is  prolonged  upon  the  external  surface  of  each  lamella  of  the  septum 

The  Fornix  and  Corpus  Fimbriatum. 

The  fornix  (la  voute  a  trois  piliers,  k,  r  r,  fig.  278)  is  a  medullary  arch,  situated  (i, 
fig.  282)  beneath  the  corpus  callosum, 
with  which  it  is  continuous  behind, 
but  which  it  leaves  in  front,  and  then 
passes  perpendicularly  downward,  de- 
scribing a  curve  within  the  curvature 
of  the  corpus  callosum.  The  interval 
between  the  anterior  part  of  the  fornix 
and  the  corpus  callosum  is  occupied 
by  the  septum  lucidum.  To  the  term 
fornix,  used  by  the  older  writers,  the 
epithet  a  trois  piliers  has  been  improp- 
erly added  by  Winslow,  inasmuch  as 
it  expresses  a  mere  appearance ;  for 
there  are  in  reality /owr  pillars,  the  two 
anteriQf  of  which  are  closely  approxi- 
mated to  each  other,  while  the  two 
posterior  are  widely  apart. 

The  fornix  resembles  an  isosceles 
triangle  {trigone  cerebral),  having  the 
anterior  angle  very  much  elongated 
and  soon  bifurcated  ;  its  posterior  an- 
gles suddenly  diverge,  pass  downward 
and  outward,  and  are  prolonged  (r  r) 
into  the  inferior  or  reflected  portions 
or  descending  cornua  of  the  lateral 
ventricles,  where  they  constitute  Che 
corpora  fimbriata  (s) ;  or,  rather,  the 
fornix  may  be  said  to  be  composed  of 
two  perfectly  distinct  medullary  cords, 
which  are  applied  closely  to  each  other,  become  broader  and  flatter  as  they  proceed 
backward  and  downward,  and  separate  from  each  other  opposite  the  reflected  portions 
of  the  lateral  ventricles,  into  which  they  enter.  The  fornix,  therefore,  resembles  the 
letter  X  placed  horizontally,  the  anterior  limbs  of  which  are  close  to  each  other  (be- 
tween q  q)  and  very  short,  while  the  posterior  limbs  (r  r)  are  very  long  and  widely  apart. 
The  term  fornix  is  really  applicable  only  to  that  portion  which  is  applied  to  the  corpus 
callosum.  Reil,  who  has  described  and  figured  this  part  better  than  any  of  his  prede- 
cessors, not  even  excepting  Vicq  d'Azyr  and  Soemmering,  calls  the  fornix  the  twain-band. 

The  superior  surface  of  the  fornix  corresponds,  in  the  median  line,  to  the  septum  luci- 
dum in  front,  and  to  the  corpus  callosum  behind  :  on  each  side  it  is  free,  and  forms  a  part 
of  the  floor  of  the  lateral  ventricles.  The  choroid  plexuses  (jp  p)  are  sometimes  reflect 
ed  upon  the  surface  of  the  fornix. 

In  order  to  understand  the  relations  of  the  fornix  with  the  corpus  callosum,  it  is  ne- 
cessary to  bear  in  mind  that  it  is  composed  of  two  flat  medullary  bands.  Now  the  inter- 
nal contiguous  borders  of  these  bands  are  turned  upward,  and  adhere  to  the  lower  sur- 
face of  the  corpus  callosum,  so  as  to  form  a  small  vertical  septum,  which  is  continuous 
with  the  back  part  of  the  septum  lucidum.  The  medullary  fibres  of  the  septum  lucidum 
are  therefore  generally  considered  to  be  continuous  with  those  of  the  fornix. 

The  inferior  surface  of  the  fornix  (r  r,  fig.  279)  rests  upon  the  velum,  interpositum  {v), 
which  separates  it  from  the  third  ventricle  (c  b  x,  fig.  280)  and  the  optic  thalami  {I  I),  the 
internal  portion  of  which  bodies  is  covered  by  the  fornix  (see^o'.  278).  It  is  upon  the 
posterior  portion  of  this  inferior  surface,  where  the  two  medullary  bands  of  the  fornix 
separate  from  each  other  to  enter  the  descending  cornua  of  the  lateral  ventricles,  that 
we  find  that  regular  though  variable  arrangement  of  transverse  fibres  (s),  abutting  on 
certain  longitudinal  fibres  (r  r),  which  has  been  named  the  lyra,  corpus  psalloides  or  psal- 
terium.  I  have  already  noticed  this  structure,  which  was  erroneously  regarded  by  Gall 
as  composed  of  the  uniting  fibres  of  the  fornix. 

The  edges  of  the  fornix  are  thin  and  free,  and  are  bordered  by  the  choroid  plexuses. 

The  anterior  pillars  of  the  fornix  {k,  figs.  279,  280),  which  Vieussens,  Tarin,  and  others 
described  as  arising  almost  indifferently  either  from  the  cerebral  peduncles,  or  from  the 
anterior  commissure  (c,  fig.  280,  situated  in  the  third  ventricle),  can  only  be  well  seen 
in  a  longitudinal  vertical  section  of  the  cerebrum  made  exactly  in  the  median  line.  Each 
half  of  the  cei-ebrum  will  contain  the  corresponding  band  of  the  fornix ;  and  it  will  then 
be  seen,  as  was  first  described  by  Santorini,  that  each  anterior  pillar  (seen  below  k  and 
behind  c,fig.  282)  arises  from  the  corpus  albicans  (z)  of  its  own  side  :  hence  these  bodies 


740  NEUROLOGY. 

have  been  called  the  bulbs  of  the  fornix.  The  whole  of  the  white  covering  of  each  of  the 
corpora  albicantia  (/,  fig.  283)  appears  to  be  formed  into  a  thick  white  fasciculus  or  cord, 
which  passes  upward,-  and  may  be  very  easily  traced  with  the  handle  of  the  scalpel 
through  the  soft  gray  matter  which  forms  the  inferior  and  anterior  portion  of  the  wall  of 
the  third  ventricle.  While  passing  through  this  gray  matter  the  cord  describes  a  curve, 
having  its  concavity  turned  backward,  and  is  situated  between  the  optic  thalamus  and 
the  corpus  striatum,  and  behind  the  anterior  commissure  {c,fig.  282  ;  m,  fig.  283) ;  having 
emerged  from  the  gray  matter,  which  is  still  prolonged  along  its  anterior  surface  and 
thus  reaches  the  septum  lucidum  {t),  the  anterior  pillar  is  reflected  backward  {h,  fig.  283) 
in  front  of  the  optic  thalamus,  and  becomes  changed  into  a  flat  band  {k,fig.  282),  which 
is  applied  to  the  thalamus  (/),  and  follows  the  contour  of  that  body  :  at  the  point  where 
the  anterior  pillar  of  the  fornix  changes  from  an  ascending  to  a  horizontal  direction,  it 
forms  half  a  ring  (situated  behind  and  below  k,fig.  282),  which  is  completed  by  the  an- 
terior part  of  the  optic  thalamus.  This  is  the  opening  of  the  foramen  of  Monro,  by  which 
a  communication  is  established  (opposite  q  q,  fig.  278)  between  the  third  and  the  corre- 
sponding lateral  ventricles. 

The  Posterior  Pillars. — Having  arrived  opposite  the  back  part  of  the  optic  thalamus, 
each  of  the  lateral  bands  of  the  fornix,  which  had  already  been  directed  somewhat  ob- 
liquely outward,  passes  abruptly  and  very  obliqely  outward  and  downward  (r  r)  into  the 
descending  cornu  (A)  of  the  corresponding  lateral  ventricle,  and  is  there  divided  y;ito  two 
parts,  one  of  which  forms  the  superficial  medullary  substance  of  the  cornu  ammonis,  or 
hippocampus  major  (m),  while  the  other  follows  the  concave  border  of  the  hippocampus, 
and  takes  the  name  o{  corpus  fimhriatum  (s),  corps  frangi,  corps  borde.  We  shall  again  al- 
lude to  these  parts  in  describing  the  lateral  ventricle. 

I  have  said  that  the  anterior  pillars  arise  from  the  corpora  albicantia,  but  they  have  a 
much  deeper  origin,  which  was  figured  by  Vicq  d'Azyr,  and  has  been  still  better  descri- 
bed by  Reil.  According  to  that  anatomist,  they  arise  within  the  optic  thalami.  I  have 
traced  them  much  farther  than  Reil,  as  far  as  the  tcenia  semicircularis  on  each  side  ;  or, 
rather,  each  tania  semicircularis  {n,  fig.  278),  which  is  situated  in  the  lateral  ventricle  be- 
tween the  corpus  striatum  (i)  and  the  optic  thalamus  {I),  and  which  is  continuous  with 
the  anterior  corpus  quadrigeminum  or  natis  of  its  own  side,  becomes  subdivided  into  two 
bands,  which  may  be  regarded  as  the  roots  of  the  corresponding  anterior  pillar  of  the  for- 
nix. Of  these  two  roots,  one  is  superficial  (w),  and  easily  seen  without  dissection  ;  the 
other  is  deep-seated  {v,  fig.  283),  enters  into  the  substance  of  the  optic  thalamus,  runs 
forward  to  the  corpus  albicanus  (/),  spreads  out  and  forms  the  surface  of  that  body,  and 
then  curves  upward  to  constitute  the  anterior  pillar  of  the  fornix  (A),  at  the  point  where 
it  emerges  from  the  gray  matter. 

The  two  bands  of  the  fornix  also  receive  some  other  white  fibres,  which  greatly  mul- 
tiply its  connexions.  Thus,  as  they  are  traversing  the  gray  matter,  the  anterior  pillars 
receive  additional  medullary  fibres,  some  arising  from  the  gray  matter  itself,  and  others 
from  the  commissure  of  the  optic  nerves  ;  again,  just  as  they  emerge  from  the  gray  mat- 
ter to  become  horizontal,  they  receive  a  considerable  cord,  formed  conjointly  by  the  white 
fibres  covering  the  optic  thalamus  {g,  fig.  283)  by  a  white  band,  which  runs  longitudinal- 
ly along  the  optic  thalamus,  and  is  continuous  with  the  corresponding  peduncle  of  the 
pineal  gland,  and  by  the  superficial  fibres  of  the  taenia  semicircularis,  of  which  I  have  al- 
ready spoken.  These  three  sets  of  fibres  form  a  cord  of  considerable  size,  which  is  bent 
abruptly  backward,  and  becomes  continuous  with  the  fornix.  Lastly,  the  fornix  receives 
or,  perhaps,  it  gives  origin  to,  the  white  radiated  fibres  of  the  septum  lucidum. 

Fig.  279.  ffig  Velum  Interpositum. 

Beneath  the  fornix  is  situated  a  vascu  ar  memorane,  a  pro- 
longation of  the  external  pia  mater  :  this  is  the  velum  interposi- 
tum, or  tela  choroidea  (v,  fig.  279),  so  named  by  Herophilus  from 
its  tenuity,  which  he  compared  to  that  of  the  fcetal  membrane 
called  the  chorion. 

It  is  thus  formed :  the  external  pia  mater,  having  arrived  be- 
low the  enlarged  posterior  extremity  of  the  corpus  callosum, 
penetrates  (at  r,fig.  282)  into  the  interior  of  the  brain  between 
that  body  and  the  tubercula  quadrigemina,  and  forms  a  sort  of 
triangular  web  {v,  fig.  279),  the  base  of  which  is  turned  back- 
ward, and  the  truncated  and  bifurcated  apex  forward.  The  up- 
per surface  of  the  velum  is  covered  by  the  fornix  (reflected  at 
r  r),  to  which  it  transmits  a  great  number  of  vessels.  Its  infe- 
rior surface  forms  the  root  of  the  third  ventricle,  and  corresponds 
on  each  side  to  the  upper  and  to  a  small  part  of  the  inner  sur- 
face of  the  optic  thalami  (/  /).  The  velum  is  also  in  relation  with 
the  venae  Galeni  and  with  the  pineal  gland  {p,  fig.  282),  adhering 
very  closely  to  that  body,  and  forming  a  nearly  complete  invest- 
ment for  it,  so  that  they  are  almost  always  removed  together 


THE   MIDDLE    OR    THIRD    VENTRICLE. 


741 


Sicfiat  Sescribed  his  so-called  arachnoid  canal  as  passing  beneath  the  velum  interposi- 
tum.  Upon  the  lower  surface  of  the  velum,  which  can  only  be  properly  examined  from 
below,  are  found  two  small  trains  of  red  granulations,  precisely  similar  to  the  choroid  plex- 
uses of  the  lateral  ventricles,  with  which  they  are  continuous  in  front :  they  may  be  call- 
ed the  choroid  plexuses  of  the  third  ventricle. 

The  lateral  borders  of  the  velum  are  continuous  with  the  upper  part  of  the  choroid  plex- 
uses {pp,figs.  278,  279)  of  the  lateral  ventricles. 

The  anterior  extremity,  or  apex  of  the  velum,  is  bifid ;  each  branch  of  the  bifurcation 
passes  from  the  third  into  the  corresponding  lateral  ventricle  (behind  k,Jig.  282,  opposite 
q  q,  Jig.  278),  behind  the  anterior  pillar  of  the  fornix,  and  constitutes  the  anterior  extrem- 
ity of  the  choroid  plexus. 

The  velum  interpositum  is  formed  by  the  pia  mater,  supported  by  a  tolerably  strong 
fibrous  layer. 

When  the  fornix  and  the  velum  (as  in  Jig.  280)  are  removed,  we  arrive  at  a  cavity  call- 
ed the  middle  or  third  ventricle. 

The  Middle  or  Third  Ventricle. 
Dissection. — In  order  to  expose  the  third  ventricle  from  the  base  of  the  brain,  the  right 


Fig.  280. 


peduncle  of  the  cerebrum  and  the  right 
corpus  albicans  should  be  separated 
from  those  of  the  left  side  by  a  longi- 
tudinal section  in  the  median  line. 
There  is  another  section,  which  I  rec- 
ommend as  exceedingly  well  adapted 
to  exhibit  all  the  parts  contained  in  the 
third  ventricle  ;  it  is  made  from  before 
backward,  and  on  either  the  right  or 
left  side  of  the  median  line,  so  as  to 
leave  both  of  the  lateral  walls  of  the 
third  ventricle  uninjured. 

The  third  ventricle  (c  to  x,  figs.  280, 
282)  is  situated  in  the  median  line,  near 
the  base  of  the  brain,  between  the  op- 
tic thalmi  (Z  I,  fig.  280)  and  in  front  of 
the  tubercula  quadrigemina  {fg) :  it  ap- 
pears like  a  very  narrow  cavity,  oblong 
from  before  backward,  and  of  greater 
extent  below  than  above  ;  it  is  not  so 
much  a  cavity  as  a  fissure  between  the 
two  optic  thalami.  Vesalius  compared 
this  ventricle  to  a  valley,  the  hills  on 
either  side  of  which  were  very  closely 
approximated  to  each  other,  and  uni- 
ted by  a  sort  of  bridge,  represented  by 
the  commissura  mollis  {h). 

The  superior  orijice  of  the  third  ven- 
tricle is  surrounded  by  a  white  rim  or 
border  (s),  which  forms,  behind  and  on 
either  side,  the  peduncles  of  the  pineal 
gland. 

The  lateral  walls  {I,  fig.  282)  are  plane,  smooth,  and  of  a  gray  colour  ;  they  are  formed 
by  two  very  distinct  parts,  viz.,  above  and  behind  by  the  internal  surface  of  the  optic 
■thalamus,  and  below  and  in  front  by  the  internal  surface  of  a  gray  mass,  which  appears 
to  me  to  deserve  a  particular  description  under  the  name  of  the  gray  mass  of  the  third 
ventricle. 

That  part  of  the  internal  wall  of  the  ventricle  which  is  formed  by  the  optic  thalamus 
is  marked  off  by  a  horizontal  groove  from  the  part  formed  by  this  gray  mass. 

The  internal  surface  of  this  gray  mass  is  smooth,  and  lined  by  the  membrane  of  the 
ventricle.  The  externed  surface  is  continuous  with  the  rest  of  the  brain  ;  below,  it  forms 
the  tuber  cinereum,  or  base  of  the  infundibulum,  passes  around  the  corpora  albicantia, 
the  anterior  pillars  of  the  fornix  and  their  roots,  is  prolonged  upward  upon  the  sides  ot 
the  septum  kicidum,  and  downward  as  far  as  the  upper  surface  of  the  optic  commissure, 
the  posterior  border  of  which  is  imbedded  in  this  gray  mass,  and  receives  from  it  a  short 
white  root  on  each  side. 

The  lateral  walls  of  the  third  ventricle  are  united  together,  opposite  the  anterior  part 
of  the  optic  thalami,  by  a  gray  substance  called  the  soft  commissure,  commissura  rnollis  (b), 
the  gray  commissure,  and  also  the  vascular  commissure  of  the  optic  thalami ;  it  varies  much 
lu  size,  and  is  very  easily  torn  ;  but  I  have  always  found  the  remains  of  it  in  those  cases 


T®!  NEUROLOGY. 

in  which  it  appeared  at  first  sight  to  be  wanting.*  I  regard  the  soft  commissure  as  a 
prolongation  of  the  gray  mass  of  the  third  ventricle,  and  this  substance  appears  to  me  to 
be  of  the  same  nature  as  the  gray  matter  of  the  convolutions. 

The  floor  of  the  third  ventricle  is  of  greater  extent  than  the  walls  of  that  cavity ;  it  is 
concave  upon  its  upper  or  ventricular  surface,  and  convex  below.  We  shall  divide  it 
into  three  portions  :  the  posterior  portion  of  the  floor  (above  n,  fig.  282)  is  deeply  grooved 
along  the  median  line,  forms  an  inclined  plane  sloping  downward  and  forward,  and  cor- 
responds to  the  interval  between  the  peduncles  of  the  cerebrum  ;  its  white  colour,  which 
is  scarcely  concealed  by  the  thin  layer  of  gray  matter  upon  it,  contrasts  strongly  with 
the  distinct  gray  colour  of  the  lateral  walls.  The  middle  portion  of  the  floor  is  funnel- 
shaped,  and  corresponds  to  the  corpora  albicantia  {z),  and  to  the  infundibulum  (i) ;  it  leads 
to  the  canal  in  the  infundibulum.  The  anterior  portion  of  the  floor  (m)  is  inclined  down- 
ward and  backward,  and  is  formed  by  a  very  thin,  semi-transparent  layer  of  gray  sub- 
stance {lamina  cinerea),  which  we  may  call,  with  Tarin,  the  pars  pellucida,  and  which  is 
supported  by  a  fibrous  layer  derived  from  the  pia  mater. 

In  front,  the  third  ventricle  presents  the  anterior  pillars  {k,fig.  280,  below  I,  and  be- 
hind c,  fig.  282)  of  the  fornix,  in  front  of  which  is  situated  a  white  cylindrical  cord  (c), 
directed  transversely,  and  visible  only  in  its  middle  portion  ;  this  is  the  anterior  commis- 
sure, beneath  which  the  ventricle  extends  as  far  as  opposite  the  posterior  border  of  the 
optic  commissure.  Beliind  the  anterior  pillars  of  the  fornix,  and  somewhat  above  the 
anterior  commissure,  are  the  two  openings  by  which  the  third  ventricle  communicates 
with  the  lateral  ventricles  {foramen  Monroi) ;  these  openings  (of  which  one  is  seen  be- 
tween b  and  k,fig.  282)  are  of  an  oval  shape,  are  sometimes  of  unequal  size,  and  become 
much  enlarged  in  chronic  effusion  into  the  ventricles.  The  two  divisions  of  the  ante- 
rior extremity  of  the  velum  interpositum  pass  through  these  openings,  to  become  con- 
tinuous (at  q  q,  fig.  278;  with  the  choroid  plexuses.  Haller  erroneously  regarded  them 
as  accidental ;  an  opinion  that  was  founded  upon  several  pathological  observations,  from 
which  it  appeared  that  the  lateral  ventricles  were  distented  with  a  considerable  quantity 
of  fluid,  while  the  third  ventricle  remained  empty. 

At  the  back  part  of  the  third  ventricle  is  seen  the  posterior  commissure  {x,  figs.  280, 
282),  a  transverse  cylindrical  cord,  situated  in  front  of  the  tubercula  quadrigemina,  and 
below  the  commissure  of  the  pineal  gland,  with  which  it  is  continuous.  The  posterior 
commissure  is  smaller  than  the  anterior ;  it  may  be  regarded  as  a  white  commissure  of 
the  optic  thalami,  for  its  extremities  are  lost  in  their  interior.  It  forms  a  sort  of  bridge 
above  the  anterior  orifice  of  the  aqueduct  of  Sylvius. 

The  Aqueduct  of  Sylvius. 

The  aqueduct  of  Sylvius,  or  aqueduct  of  the  corpora  quadrigemina,  which  was  descn- 
oed  by  both  Galen  and  Vesalius,  and  by  the  latter  quite  as  perfectly  as  by  the  anatomist 
after  whom  it  was  named,  is  a  canal  which  establishes  a  communication  between  the 
third  and  fourth  ventricles  {I  v,fig.  282) — iter  a  tertio  ad  quartern  ventriculum ;  it  passes 
through  the  isthmus  of  the  encephalon,  in  the  median  hue,  below  the  tubercula  quadri- 
gemina (/^).  It  is  directed  obliquely  downward  and  backward.  Its  walls  are  dense, 
and  lined  by  the  membrane  of  the  ventricles.  This  canal  presents  both  on  its  upper  and 
its  lower  wall  a  longitudinal  groove  or  median  furrow,  bounded  by  two  small  longitudi- 
nal cords.  The  median  furrow  on  the  lower  wall  is  continuous  with  the  longitudinal 
gioove  of  the  calamus  scriptorius.  The  brothers  Wenzel  have  given  a  minute  descrip- 
tion of  these  two  furrows,  and  they  have  also  noticed  two  lateral  furrows.  It  was  stated 
by  Vieussens  that  the  opening  of  the  aqueduct  into  the  fourth  ventricle  was  provided 
with  a  valve.     But  his  statement  is  at  variance  with  the  results  of  observation. 

It  follows,  therefore,  from  the  preceding  description,  that  the  third  ventricle  has  four 
openings,  two  of  which  communicate  with  the  lateral  ventricles,  the  third  opens  into  the 
fourth  ventricle,  and  the  fourth  (between  b  and  x,  380)  leads  into  the  infundibulum. 

The  third  ventricle,  moreover,  has  three  conunissures  :  one  composed  of  gray  matter, 
viz.,  the  commissura  mollis,  or  commissure  of  the  optic  thalami ;  the  other  two  of  white 
substance,  one  being  anterior  and  the  other  posterior. 

The  Conarium,  or  Pineal  Gland. 

The  conarium,  pineal  gland,  or  pineal  body,  is  a  small  grayish  body  ( p,  figs.  280,  282) 
situated  in  the  median  plane,  behind  the  posterior  commissure  of  the  third  ventricle,  and 
between  the  nates,  upon  which  it  rests. 

It  is  retained  in  this  situation  by  two  small  medullary  cords,  which  are  Ccdled  its  ped- 
uncles, and  by  the  velum  interpositum,  below  which  it  is  placed,  and  by  which  it  is  almost 
completely  invested  as  with  a  closely-adherent  sheath :  the  adhesion  between  these  parts 
is  so  intimate  that  they  are  almost  always  removed  together ;  and  hence  some  anato- 
mists have  regarded  the  conarium  as  a  dependance  of  that  membrane,  and  others,  who 

*  Out  of  sixty-six  brains  of  subjects  of  all  ages  examined  by  the  brothers  Wenzel,  the  soft  oommissure  was 
found  in  fifty-six.  It  was,  therefore,  wanting  in  ten  cases.  The  facility  with  which  it  is  lacerated  may  have 
misled  these  industrious  investigators  into  a  belief  that  its  absence  was  more  frequent  than  it  actually  is. 


THE   CONARIUM,  OB  PINEAL   GLAND.  /43 

hare  not  been  careful  in  their  examinations,  have  declared  that  it  is  sometimes  want- 
ing in  the  human  subject.  This  body,  however,  always  exists  in  man  and  the  mamma- 
lia. It  is  wanting  in  birds  and  fishes,  and  in  reptiles,  with  the  exception  of  the  tortoise, 
in  which  it  is  so  remarkably  large  that  it  forms  by  itself  a  kind  of  brain. — (Desmoulins, 
Anat.  dti  Syst.  Nerv.,  t.  i.,  p.  211.) 

This  body  is  shaped  like  a  cone,  having  its  adherent  base  turned  forward  and  its  free 
apex  backward ;  hence  its  name  of  conarium  {Oribasius,  Galen) ;  it  has  also  been  com- 
pared to  a  pine  cone,  and  has  been  named  the  pineal  gland,  or  jiineal  body.  Its  form, 
however,  is  subject  to  some  variety ;  it  is  sometimes  spheroidal,  and  at  other  times  cor- 
diform,  from  being  notched  at  the  beise. 

The  pineal  body  is  small,  being  only  about  four  lines  in  length,  and  from  two  to  three 
lines  wide  at  the  beise.  Its  size,  in  the  animal  series,  does  not  appear  to  bear  any  pro- 
portion to  the  size  of  the  cerebrum,  or  of  the  cerebellum,  or  of  the  tubercula  quadrigem- 
ina,  so  that  comparative  anatomy  throws  no  light  upon  this  obscure  subject.  Neither 
age  nor  sex  has  any  influence  upon  the  development  of  this  small  body. 

Relations. — The  conarium  or  pineal  gland,  enclosed  in  the  pia  mater,  Hke  the  cere- 
brum and  cerebellum,  rests  upon  the  slight  triangular  depression  between  the  nates :  the 
venae  Galeni  run  along  its  sides. 

When  stripped  of  the  pia  mater,  it  is  free  in  all  directions,  excepting  at  its  base,  which 
is  connected  with  the  encephalon  by  a  transverse  commissure,  situated  above  the  posteri- 
or commissure  of  the  cerebrum,  and  hy /our  slender  peduncles,  two  of  which  are  superior 
and  two  inferior.  The  superior  peduncles  (s,  Jigs.  280,  282),  which  are  the  only  ones  gen- 
erally described,  form  together  a  sort  of  loop,  the  two  ends  of  which  run  along  the  tops 
of  the  optic  thalami ;  they  have  been  named  the  reins  of  the  pineal  body  {habence).  We 
have  already  seen  that  they  are  continuous  with  the  fornix.  The  inferior  peduncles, 
which  are  distinctly  seen  only  upon  a  longitudinal  vertical  section  through  the  middle  of 
the  cerebrum,  arise  from  the  base  of  the  pineal  body,  pass  vertically  downward  upon  the 
back  part  of  the  internal  wall  of  the  third  ventricle,  and  may  be  traced  to  the  lower  part 
of  that  cavity.* 

Colour  and  CoTisistence. — The  reddish-gray  colour  of  the  pineal  body  contrasts  strong- 
ly with  the  whiteness  of  its  commissure  and  peduncles.  The  colour  and  consistence  of 
this  body  exactly  resemble  those  of  the  gray  matter  of  the  cerebral  convolutions.  If  it 
be  compressed  between  the  fingers,  a  viscid  juice  exudes,  and  certain  small  concretions 
are  found  in  it,  which  I  shall  notice  after  having  described  the  structure  of  this  organ. 

Structure. — At  the  base  of  the  pineal  body  are  seen  some  white  or  medullary  fibres, 
which  arise  from  the  conuuissure  and  from  the  superior  peduncles  of  that  organ.  These 
white  fibres  spread  out  into  a  tuft,  and  terminate  abruptly.  All  the  rest  of  the  conarium 
consists  of  gray  matter.  On  making  a  horizontal  section  of  this  body,  it  is  sometimes  found 
to  be  solid,  and  sometimes  to  be  hollow,  and  to  contain  a  transparent,  viscid  fluid.  The 
cavity  is  lined  by  a  vascular  membrane,  and,  according  to  Meckel,  by  a  layer  of  medul- 
lary substance,  which  I  have  never  seen.  It  has  been  stated  that  it  communicates  with 
the  third  ventricle ;  but  I  am  inclined  to  believe,  with  Santorini  and  Gerardi,  that  the 
conmiunicating  orifice  admitted  by  some  authors  is  the  result  of  traction  upon  the  base 
of  the  conarium  in  attempting  to  remove  the  pia  mater. 

When  the  pineal  body  contains  no  distinct  cavity,  which  is  not  unfrequently  the  case, 
the  viscid  fluid  is  distributed  through  it  as  through  a  sponge. 

As  to  the  nature  of  this  body,  it  appears  to  consist  of  a  soft  gray  substance,  traversed 
by  a  great  number  of  bloodvessels,  having  a  very  close  resemblance  to  the  gray  matter 
of  the  brain,  but  none  whatever  to  glandular  tissues. 

Concretions  of  the  Conarium. — One  of  the  most  curious  circumstances  in  regard  to  this 
body  is  the  existence  in  it  of  certain  hard  concretions,  which  Ruysch  and  others  regard- 
ed as  small  bones,  an  error  which  was  successfully  combated  by  Soemmering.  The 
use  of  them  is  utterly  unknown. 

Are  these  concretions  constant  1  The  brothers  Wenzel  found  them  wanting  in  six 
brains  out  of  one  hundred.  Soemmering  states  that  he  found  them  in  fifteen  brains, 
among  which  were  some  of  very  young  infants,  and  he  adds  that  they  exist  in  the  foetus 
before  the  full  period.  Meckel  says  they  do  not  appear  until  the  sixth  or  seventh  year, 
beyond  which  age  he  always  found  them. 

These  concretions  sometimes  form  a  single  mass  (acervulus,  Sammering),  resembling 
a  granular  lump  of  salt ;  sometimes,  and  most  commonly,  there  are  a  great  number  of 
them. 

They  appear  as  aggregated  granules,  which  the  Wenzels  believed  to  be  connected  by 
means  of  a  proper  membrane.  .     .'      . 

Seat  of  the  Concretions. — When  the  pineal  body  is  hollow,  they  are  found  in  its  interi- 
or ;  but  when  it  is  solid,  they  are  situated  upon  the  surface  of  this  body.  I  have  found 
them  several  times  upon  its  peduncles. 

•■'  Ridley  describes  certain  white  striae,  arising  from  the  pineal  body,  and  terminating  in  the  testes.  Gall 
Bays  that  the  inferior  peduncles  are  directed  backward,  and  somewhat  downward,  to  become  continuou*  with 
the  snb'acent  white  lamina.     Plate  xi.,  text,  p.  223. 


m 


NEUROLOGY. 


They  are  of  an  opaline  yellow  colour  in  old  subjects,  and  are  whitish  in  the  young. 
According  to  Pfaff,  they  consist  of  phosphate  of  lime,  carbonate  of  lime,  and  an  animal 
matter. 

They  were  incorrectly  regarded  as  morbid  deposites  by  Morgagni,  who  supposed,  with- 
out proof,  that  they  might  produce  cerebral  affections  of  greater  or  less  severity. 

Function  of  the  Pineal  Gland. — The  hypothesis  of  Des  Cartes  concerning  the  function 
of  this  body,  which  was  so  completely  refuted  by  Steno,  is  a  striking  example  of  the 
abuse  of  an  imperfect  knowledge  of  anatomy  ;  according  to  Des  Cartes,  the  soul  is  seated 
in  the  pineal  gland,  and  it  directs  all  the  movements  of  the  body  by  means  of  the  pedun- 
cles, which  he  regarded  as  the  gubernacula  or  reins  of  the  soul.  M.  Magendie  thinks 
that  this  body  performs  certain  functions  having  reference  to  the  cerebro-spinal  fluid : 
he  has  regarded  it  as  a  kind  of  plug,  which  would  obstruct  the  orifice  of  communication 
between  the  third  and  fourth  ventricles  ;  but,  in  the  first  place,  it  is  completely  fixed  by 
the  pia  mater  ;  and  in  the  second  case,  even  if  it  were  free,  it  could  not  in  any  case  close 
the  orifice  alluded  to.  Morbid  conditions  of  this  body  will  perhaps  throw  some  light  upon 
its  functions,  but  they  have  not  yet  been  sufficiently  studied.  The  existence  of  a  cavity 
within  the  pineal  gland,  added  to  the  fact  that  it  is  sometimes  the  seat  of  dropsy,  would 
seem  to  indicate  that  its  functions  are  connected  with  secretion. 

The  Lateral  Ventricles. 

Dissection. — The  lateral  ventricles  are  exposed  by  the  same  dissection  as  that  which 
we  have  pointed  out  for  the  examination  of  the  fornix  and  septum  lucidum,  that  is  to 
say,  by  removing  the  upper  parts  of  the  hemispheres  and  dividing  the  corpus  callosum 
on  each  side  of  the  median  line  (as  in  fig.  278,  on  the  left  side).  In  order  to  trace  the 
reflected  portion  or  descending  cornu,  it  should  be  laid  open  by  cutting  through  its  outer 
wall  from  behind  forward.  There  is  also  a  great  advantage  in  studying  this  part  of  the 
lateral  ventricles  from  the  base  of  the  brain. 

The  lateral  ventricles  {fig  h,fig.  278)  are  two  in  number;  they  are  much  larger  than 
the  other  ventricles ;  are  placed  symmetrically  one  on  each  side  of  the  median  line ; 
they  are  separated  from  each  other,  but  communicate  through  the  medium  of  the  third 
ventricle  ;  their  upper  part  is  nearer  to  the  base  of  the  brain  than  to  its  upper  surface, 
and  they  approach  still  nearer  to  the  base  by  their  reflected  portion  or  descending  cornu. 

Each  lateral  ventricle  commences  (/)  in  the  substance  of  the  anterior  lobe  (a),  a  little 
in  front  of  the  third  ventricle,  and  behind  the  anterior  reflected  extremity  of  the  corpus 
callosum  (c),  by  which  it  is  bounded  in  front ;  from  this  point  it  passes  vertically  upward 
and  backward,  describing  a  curve  with  its  convexity  directed  inward  ;  having  reached 
(r)  opposite  the  posterior  part  of  the  third  ventricle,  it  changes  its  direction,  so  as  to 
turn  downward  and  forward  round  the  optic  thalamus  (/),  and  then  terminates  (h)  in  the 
substance  of  the  sphenoidal  portion  of  the  posterior  lobe  [i.  c,  in  the  middle  lobe]  (c)  be- 
hind the  fissure  of  Sylvius,  and,  consequently,  a  little  below  and  behind  the  point  (/)  at 
which  it  commences.  At  the  point  of  its  reflection  it  also  sends  a  prolongation  (g) 
backward  into  the  occipital  portion  of  the  posterior  lobe  (J).  From  this  it  will  be  under- 
stood why  each  lateral  ventricle  has  been  compared  to  a  capital  italic  £  turned  upside 
down,  and  why  the  cavity  is  said  to  have  three  cornua,  viz.,  an  anterior  or  frontal  (/), 
an  inferior,  descending  or  sphenoidal  (A),  and  a  posterior  or  occipital  cornu  (g) ;  on  this  ac- 
count the  lateral  ventricles  are  frequently  denominated  ventriculi  tricornes. 

It  is  also  seen  that  the  ventricles  are  applied  to  each  other  at  their  anterior  extremi- 
ties, but  diverge  behind  like  the  limbs  of  the  letter  x. 

The  general  form  of  the  lateral  ventricles  is  very  well  shown  upon  a  longitudinal  sec- 
tion of  the  cerebrum  through  the  median  line  ;  each  of  these  ventricles  is  then  seen  to 
be  nothing  more  than  an  elliptical  canal  or  passage,  which  runs  around  the  large  ellip- 
soid mass  formed  by  the  optic  thalamus  and  corpus  striatum.  This  elliptical  canal  is 
ooly  interrupted  below  and  in  front  opposite  the  fissure  of  Sylvius.  Anatomists  describe 
in  each  lateral  ventricle  a  superior  portion,  an  inferior  portion,  and  a  posterior  portion  or 
digital  cavity. 

The  Superior  Portion  of  the  Lateral  Ventricle. 

This  portion,  called  the  body  of  the  ventricle  (i),  is  broader  in  front  than  behind,  and 
presents  for  our  consideration  a  superior,  an  inferior,  and  an  internal  wall. 

The  superior  uall,  or  the  roof,  is  formed  by  the  under  surface  of  the  corpus  callosum. 

The  inferior  wall,  or  the  floor,  is  formed  by  the  ventricular  surfaces  of  the  corpus  striatum 
(i)  and  optic  thalamus  {1} ;  between  these  two  bodies  are  found  the  lamina  cornea  and 
t(eni&  scmicircularis  (m). 

The  Corpus  Striatum. — When  examined  from  the  lateral  ventricle,  each  of  the  corpora 
striata  (i  i,figs.  278,  280)  appears  like  a  pear-shaped  or  conoidal  eminence,  having  its 
larger  end  turned  forward,  and  its  other  end,  which  is  very  narrow,  prolonged  backward, 
into  the  reflected  portion  of  the  ventricle.  Its  gray  colour  contrasts  with  the  whiteness 
of  the  surrounding  parts.  Its  free  surface  is  covered  by  the  lining  menibruiie  of  the  ven- 
tricles, and  is  very  regularly  marked  by  certain  large  veins  which  run  neross  it. 


THE  LATERAL  VENTRICLE.  745 

The  ventricular  surface  of  the  corpus  striatum  fonns  only  one  portion  of  this  body, 
which  has  received  its  name  from  the  white  bundles  or  striee  which  traverse  the  gray 
matter,  of  which  it  is  principally  composed. 

The  corpus  striatum,  considered  as  a  whole,  is  an  ovoid  gray  mass,  lodged  in  a  deep 
excavation  formed  opposite  the  insula  or  island  of  Reil,  which  is  situated  in  the  fissure 
of  Sylvius,  and  which  I  propose  to  name  the  lobule  of  the  corpus  striatum.  It  will  be  seen, 
hereafter,  that  the  corpus  striatum  is  covered  on  the  outer  side  by  the  convolutions  of 
the  insula,  that  it  corresponds  on  the  inner  side  with  the  optic  thalamus  and  the  gray 
matter  of  the  third  ventricle,  and  that  it  is  exposed  below,  at  the  back  part  of  the  ante- 
rior lobes  of  the  brain,  behind  the  convolutions  which  form  the  sides  of  the  furrow  for 
the  olfactory  nerve. 

The  aplic  thalami  {I  I,  Jig.  280),  which,  as  we  have  already  seen,  constitute  the  lateral 
walls  of  the  third  ventricle,  form  also,  by  their  upper  surface,  a  part  {I,  fig.  278)  of  the 
floor  of  the  corresponding  lateral  ventricle  ;  this  surface,  which  is  oblong  from  before 
backward,  conunences  about  six  lines  from  the  anterior  extremity  of  the  lateral  ventri- 
cle :  it  is  covered  by  the  choroid  plexus  ( p)  and  the  fornix  (k) :  the  corresponding  ante- 
rior pillar  of  the  fornix  turns  round  its  anterior  extremity,  and  the  interval  between  the 
pillar  and  the  thalamus  forms  the  opening  of  communication  between  the  third  and  the 
corresponding  lateral  ventricle.  The  brownish-white  colour  {couleur  cafe  au  lait)  of 
the  optic  thalamus  distinguishes  it  from  the  corpus  striatum,  which  lies  along  its  outer 
side,  the  lamina  cornea  and  the  taenia  semicircularis  marking  the  limits  between  these 
two  bodies. 

The  lamina  cornea  is  a  thick,  semi-transparent  band,  of  a  homy  aspect,  which  was  com- 
pared by  Tarin  to  a  plate  of  horn,  and  which  appears  to  be  nothing  more  than  a  thick- 
ened portion  of  the  lining  membrane  of  the  ventricle.  Beneath  and  protected  by  it  is 
found  the  vein  of  the  corpus  striatum,  which  receives  the  venous  branches  already  de- 
scribed upon  the  surface  of  that  body.  Beneath  the  vein  is  seen  a  small,  white,  linear 
band  («),  to  which  Willis  first  directed  attention  as  the  limhus  posterior,  and  which  is 
now  called  the  tania  semicircularis. 

I  would  observe,  that  the  lamina  cornea  and  the  taenia  semicircularis  are  two  very 
distinct  structures,  which  most  anatomists  have  erroneously  confounded. 

More  deeply,  the  limits  between  the  corpus  striatum  and  optic  thalamus  are  marked 
by  a  white  layer,  described  by  Vieussens  as  the  geminum  centrum  semicirculare,  or  double 
semicircular  centre. 

The  lateral  portion  of  the  fornix  and  the  choroid  plexus  (see  fig.  278)  must  also  be  re- 
garded as  entering  into  the  formation  of  the  floor  of  the  lateral  ventricle.  This  lateral 
portion  of  the  fornix  resembles  a  band  applied  upon  the  optic  thalamus,  but  separated 
from  it  by  a  fissure  through  which  the  choroid  plexus  becomes  continuous  with  the  ve- 
lum interpositum  :*  the  choroid  plexus  runs  along  the  free  edge  of  this  band,  and  is  some- 
times turned  up  on  to  its  upper  surface. 

The  internal  wall,  or  septum  of  the  lateral  ventricles,  is  much  deeper  in  front,  where  it  is 
formed  by  the  septum  lucidum,  than  behind,  where  it  consists  of  a  small  vertical  portion 
of  the  fornix,  with  which  it  terminates.  We  ought  also  to  regard  as  forming  a  part  of 
the  septum  of  the  lateral  ventricles  a  prolongation  on  each  side  of  the  gray  matter  of 
the  third  ventricle,  which  passes  round  the  corresponding  anterior  pillar  of  the  fornix, 
and  upon  the  lower  part  of  the  septum  lucidum. 

The  Inferior  or  Reflected  Portion  of  the  Lateral  Ventricle. 

Dissection. — ^As  the  reflected  portion  or  descending  cornu  belongs  to  the  base  of  the 
brain,  it  is  well  to  place  the  brain  upon  its  convex  surface,  and  then  proceed  to  open  it. 

This  cornu  may  also  be  reached  from  the  great  transverse  fissure,  by  first  removing 
the  pia  mater  which  enters  there,  and  then  partially  dividing  the  lower  wall  of  the  cornu 
from  the  fissure  of  Sylvius  backward,  and  turning  back  the  lower  wall  on  itself 

The  descending  cornu  {h,fig.  278)  of  the  lateral  ventricle  has  two  walls,  a  superior  and 
an  inferior.  The  superior  wall  {b,fig.  281)  is  concave,  and,  being  moulded  upon  the  pes 
hippocampi  or  cornu  ammonis  (m),  which  forms  the  inferior  wall,  is  named  the  sheath  of 
the  pes  hippocampi. 

Upon  the  inferior  wall  are  found  the  pes  hippocampi  or  cornu  ammonis,  the  corpus  fim- 
briatum,  the  fascia  dentata,  the  great  cerebral  fissure,  and  the  reflected  portion  of  the  choroid 
plexus. 

The  cornu  ammonis  or  ram's  horn,  pes  hippocampi,i  or  foot  of  the  sea-horse,  is  a  conoidal 
eminence  {m,fig.  278)1:  curved  upon  itself,  and  having  its  larger  end  turned  forward,  and 

*  [A  comparison  of  Jigs.  1~S  and  279  will  facilitate  the  comprehension  of  this  statement,  in  the  latter  ^^. 
the  fornix  is  reflected  backward,  and  the  continuity  of  the  choroid  plexus  (p)  with  the  velum  (v)  is  shown.] 

t  [The  term  pes  hippocampi  is  generally  applied  to  the  anterior  part  only  of  this  structure,  the  whole  being 
usually  called  hippocampus  major. 

%  1  have  not  found,  like  Treviranus,  the  medullary  substance  of  the  anterior  extremity  of  the  cornu  ammo- 
nis either  continuous  or  communicating  in  any  manner  with  the  external  root  of  the  olfactory  nerve  ,  I  cannot, 
therefore,  admit  that  the  functions  of  the  cornu  ammonis  have  any  relation  with  those  of  the  nerves  in  ques- 
tion.   Treviranus  believes  that  it  assists  m  the  remembrance  of  olfactory  impressions.     It  is  unfortunate  foi 

5B 


7#6  NEUROLOGY. 

its  small  end  backward.  Its  concave  border,  which  is  directed  inward  and  forward,  is 
bounded  by  a  narrow,  thick,  and  dense  band,  which  forms  a  continuation  of  the  posterior 
pillar  of  the  fornix ;  mis  is  the  tccnia  hippocampi,  so  improperly  named  the  corpus  fimhri- 
atum,  OT  fringed  body  («). 
On  raising  up  the  taenia  hippocampi  {s,Jig:  281),  there  is  seen  beneath  it  a  band  of 
Fig.  281.  gray  matter  (d),  which  runs  along  the  inner  border  of  the  cornu  am- 

monis  :  this  gray  matter,  which  is,  as  it  were,  crenated  by  transverse 
furrows,  has  been  well  described  by  Vicq  d'Azyr,  under  the  name  of 
corps  godronni,  or  fascia  dentata. 

To  obtain  an  accurate  idea  of  the  cornu  ammonis,  it  is  necessary  to 
examine  vertical  sections  of  it,  as  was  done  by  Vicq  d'Azyr,  who  has 
given  very  good  figures  of  such  sections  :  it  is  then  seen  (as  in  fig. 
281)  that  the  hippocampus  major  {m)  is  formed  by  a  reflection  of  the 
hemisphere  inward  upon  itself,  as  the  brothers  Wenzel  have  very  well 
shown ;  and  that  it  is  composed  of  a  convolution  doubled  or  turned 
upon  itself  like  a  horn,  so  that  the  white  convex  part  expands  in  the 
interior  of  the  lateral  ventricle,  while  the  gray  concave  part  is  upon 
the  surface  of  the  cerebrum.* 

The  surface  of  a  vertical  section  of  the  hippocampus  major  also  pre- 
sents a  white  spiral  line  (below  m),  which  is  the  section  of  the  white 
covering  of  this  eminence,  and  a  rather  thick  gray  layer  (a),  which  is  subdivided  into  two 
smaller  layers  by  a  white  streak  (c) ;  all  these  are  arranged  in  a  spiral  manner. 

The  white  layer  which  forms  the  covering  of  the  cornu  anamonis  is  continuous,  on  the 
one  hand,  with  that  which  lines  the  rest  of  the  lateral  ventricle,  and  on  the  other  (by 
means  of  the  corpus  fimbriatum,  s)  with  the  corpus  callosum  and  the  fornix.  Not  un- 
frequently  a  second  pes  hippocampi  is  found  on  the  outer  side  of  the  first,  to  which  it  is 
concentric  ;  it  is  called  pes  accessorius  {eminentia  collateralis).  Meckel  erroneously  re- 
gards it  as  the  result  of  an  arrested  development. 

The  inferior  wall  of  the  descending  portion  of  the  lateral  ventricle  farther  presents  for 
our  consideration, 

The  reflected  or  descending  portion  of  the  choroid  plexus  (see  Jig.  278) ;  and  also  the  great 
transverse  fissure,  through  which  the  choroid  plexus  becomes  continuous  (opposite  s,_^^. 
281)  with  the  external  pia  mater :  the  lower  border  of  this  fissure  is  formed  by  the  hip- 
pocampus major  and  corpus  fimbriatum  ;  and  the  upper  border  by  the  lower  surface  of 
the  optic  thalamus,  which  presents  in  this  situation  the  corpus  gcniculatum  externum  (j, 
fig.  271),  an  oblong  eminence,  which  is  continuous  with  the  optic  tract,  and  the  corpus 
geniculatum  internum  (i),  a  small  rounded  eminence,  which  is  circumscribed  by  the  corpus 
geniculatum  externum. 

The  Posterior  Portion  of  the  Lateral  Ventricle. 

The  digital  or  ahcyroid  cavity  {uyKvpa,  a  hook)  is  the  occipital  portion  (g,  fig.  278)  of 
the  lateral  ventricle.  The  term  digital  cavity  has  arisen  from  its  having  been  compared 
to  the  impression  which  the  finger  would  leave  if  pushed  backward  into  the  substance 
of  the  brain.  It  commences  at  the  point  where  the  ventricle  is  reflected  upon  itself, 
passes  horizontally  backward,  describing  a  curve  with  the  convexity  turned  outward,  and 
becomes  gradually  narrower,  until  it  terminates  in  a  point.  The  dimensions  of  this 
cavity  are  extremely  variable,  not  only  in  different  individuals,  but  even  in  the  same  sub- 
ject. Thus,  a  very  large  digital  cavity  is  often  found  on  the  right  side,  while  on  the  left 
there  is  only  a  trace  of  it. 

Acute  ventricular  hydrocephalus  affects  the  digital  cavity  more  than  any  other  part  of 
the  ventricle,  t  In  some  cases  the  bottom  of  the  digital  cavity  is  not  more  than  half  a 
line  from  the  surface  of  the  brain. 

In  the  natural  state,  the  upper  wall  of  the  digital  cavity  is  exactly  fitted  to  a  conoidai 
eminence,  which  occupies  the  lower  wall  or  the  floor  of  that  cavity,  and  which  differs  in 
its  dimensions  according  to  the  size  of  the  cavity  itself  This  eminence  (n),  which  is 
variously  named  the  unciform  eminence,  colliculus,  calcar,  unguis,  was  very  well  described 
by  Morandjt  under  the  name  of  the  ergot,  and  is  therefore  generally  called  the  ergot  of 
Morand. 

In  form  it  rather  closely  resembles  the  hippocampus  major,  so  that  we  ought,  perhaps, 
to  prefer,  with  Vicq  d'Azyr,  the  name  of  hippocampus  minor.  There  is  not  only  a  cor- 
respondence in  form,  but  also  in  structure,  between  the  two  hippocampi ;  and  the  broth- 
ers W^enzel  appear  to  me  to  have  clearly  shown  that  the  ergot  of  Moraad,  like  the  hip- 

this  hypothesis,  that  the  animal  in  which  the  cornu  ammonis  is  most  developed,  viz.,  the  liare,  is  precisely 
that  in  which  there  is  least  evidence  of  memory. 

*  I  could  never  perfectly  understand  the  structure  of  the  cornu  ammonis  until  I  had  eiamined  it  in  rumi- 
nantia  and  rodentia,  but  especially  in  the  latter,  in  which  it  is  most  developed.  In  the  rodentia  the  reflected 
portion  of  the  hemisphere  is  almost  as  large  as  the  hemisphere  itself,  and  the  connexions  of  the  cornu  amnio- 
nis  with  the  fornix  are  seen  most  distinctly.  It  is  quite  evident  that  the  fornix,  the  curnu  ammonis,  and  the 
corpus  fimbriatum,  form  only  one  system  of  fibres,  and  are  continuous  with  each  other. 

t  It  is  probable  that  this  is  simply  the  mechanical  effect  of  long-continued  tying  upon  the  back. 

t  Mem.  de  I'Acad.  des  Sciences,  1744.     Observ.  Anatomiques  sur  Quelques  Parties  du  Cerveau 


THE    CHOROID   PLEXUSES,  ETC.  747 

pocampus  major,  is  nothing  more  than  a  special  convolution  projecting  into  the  ventri- 
cle. It,  in  fact,  consists  of  a  white  layer,  enclosing  a  thick  mass  of  gray  substance.  A 
longitudinal  anfractuosity,  the  depth  of  which  depends  on  the  prominence  of  the  ergot, 
denotes  on  the  surface  of  the  brain  the  situation  of  the  digital  cavity :  this  anfractuosi- 
ty is  constant,  and  I  have  already  described  it  as  the  anfractuosity  of  the  digital  cavity. 
There  is  also  another  circumstance  which  favours  the  analogy  between  the  ergot  and 
the  hippocampus  major,  and  that  is  their  continuity ;  for  there  is  only  a  depression  be- 
tween them,  and  the  white  layer  which  connects  them  is  continuous  in  both  cases  with 
the  fornix. 

Gredinsh  as  described  several  varieties  of  the  ergot ;  not  unfrequently  it  is  double,  and, 
as  we  have  mentioned,  so  is  the  hippocampus  major.  The  absence  of  the  ergot  is  re- 
garded by  Tiedemann  as  the  result  of  defective  development. 

The  ergot  and  the  digital  cavity  scarcely  exist  except  in  man,  doubtless  because  he 
alone  has  the  occipital  portion  of  the  brain  greatly  developed. 

The  Choroid  Plexuses. 

The  choroid  plexuses  of  the  brain,  which  have  already  been  noticed  in  the  descriptions 
of  the  third  and  lateral  ventricles,  form  a  continuous  system  of  vessels,  as  can  be  easily 
shown  by  examining  the  brain  from  the  base  upward.  Upon  the  under  surface  of  the 
velum  interpositum,  and  on  each  side  of  the  median  line,  are  two  small,  red,  granular 
bands,  running  from  behind  forward,  bordered  by  the  veins  of  the  corpora  striata,  and 
terminating  in  front  upon  the  convexity  of  an  arch  which  forms  the  boundary  of  the  ve- 
lum in  that  direction.  This  arch  is  formed  by  the  junction  of  the  anterior  extremities 
of  the  choroid  plexuses.  It  is  situated  behind  the  anterior  pillars  of  the  fornix,  at  the 
point  where  those  pillars  unite,  and  is  crossed  at  right  angles  by  the  veins  of  the  corpus 
striatum,  which  pass  above  it ;  after  this  junction,  the  choroid  plexuses  again  separate 
and  enter  the  lateral  ventricles  through  the  foramen  (foramen  of  Monro)  which  leads 
from  the  third  to  the  lateral  ventricles ;  within  each  of  the  lateral  ventricles  they  de- 
scribe an  elliptical  curve  {p,  fig.  278),  which  is  accurately  moulded  upon  the  optic  thala- 
mus, and  runs  along  the  fornix  in  the  upper  part  of  the  ventricle,  and  along  the  corpus 
fimbriatum  in  the  descending  comu  or  reflected  portion. 

The  upper  part  of  the  choroid  plexus  is  very  narrow ;  the  lower  part  is  three  or  four 
times  broader  than  the  upper ;  its  upper  and  under  surfaces  are  free,  and  also  its  outer 
border,  which  contains  a  large  vessel ;  its  inner  border  is  continuous  with  the  velum  in- 
terpostum*  in  the  upper  part  of  the  lateral  ventricle,  and  in  the  descending  cornu  with 
the  pia  mater,  at  the  base  of  the  brain. 

The  lining  membrane  of  the  ventricle  adheres  intimately  to  the  inner  border  of  each 
choroid  plexus,  so  that  the  lateral  ventricles  are  completely  closed,  and  no  fluid  can  es- 
cape through  the  semicircular  fissure  which  extends  along  their  entire  course. 

The  choroid  plexuses  are  granular,  or,  rather,  consist  of  vascular  tufts,  which  are  un- 
like any  other  structure  in  the  body,  and  their  uses  are  quite  unknown. 

The  Lining  Membrane  and  the  Fluid  of  the  Ventricles. 

The  middle  and  lateral  ventricles  are  lined  by  a  transparent  and  tolerably  strong  mem- 
brane, of  which  the  horny  lamina  between  the  corpus  striatum  and  thalamus  opticus  is 
a  part.  On  tracing  this  membrane  from  the  third  ventricle,  it  is  seen  to  pass  into  the 
lateral  ventricles  through  the  foramen  (of  Monro),  behind  the  anterior  pillar  of  the  for- 
nix. From  the  third  ventricle  it  dso  descends  into  the  fourth  through  the  aqueduct  of 
Sylvius. 

It  is  extremely  easy  to  demonstrate  this  membrane,  especially  upon  the  septum  luci- 
dum  and  corpora  striata,  and  in  the  digiteil  cavities. 

In  order  to  separate  it  to  any  extent,  it  must  be  dissected  from  without,  by  gradually 
removing  the  layers  of  cerebral  substance  by  which  it  is  covered.  This  separation  oc- 
curs in  acute  ventricular  hydrocephalus,  in  consequence  of  the  pultaceous  softening  of 
the  surrounding  tissue.  In  the  foetus  and  new-born  infant,  this  membrane  can  be  sep- 
arated with  the  greatest  facility,  on  account  of  its  density  and  the  softness  of  the  sur- 
rounding parts. 

Three  questions  present  themselves  regarding  the  ventricular  membrane  :  Is  it  a  se- 
rous membrane  1  Does  it  communicate  with  the  araclmoid,  so  that  it  ought  to  be  re- 
garded as  a  continuation  of  that  membrane  1  How  is  it  arranged  along  the  fissure  of 
each  lateral  ventricle  1 

That  the  ventricular  membrane  is  a  serous  membrane  is  shown  by  the  nature  of  the 
fluid  exhaled  into  the  cavity  of  the  ventricles  ;  by  the  structure  of  the  membrane  itself, 
which  consists  entirely  of  lymphatic  cellular  tissue  ;  and  by  the  diseases  of  the  ventricles, 
which  are  precisely  similar  to  those  of  other  serous  cavities. + 

*  Compare  figs.  278  and  279. 

t  The  occurrence  of  acute  aud  chrouic  serous  eflTusions,  of  purulent  formations,  aud  of  miliary  grannlatlOM 
in  the  ventricles,  are  proofs  of  the  serous  nature  of  their  lining  membrane. 
[The  ventricular  membrane  has  a  ciliated  epithelium  on  its  inner  surface.] 


im 


NEUROLOGY. 


The  number  of  veins  which  are  situated  beneath  the  ventricular  membrane  has  sug- 
gested the  notion  that  it  was  a  prolongation  or  continuation  of  the  pia  mater  ;  but  these 
vessels  do  not  belong  to  the  membrane. 

The  continuity  of  the  ventricular  membrane  with  the  arachnoid  on  the  surface  of  the 
brain  has  not  been  demonstrated.  I  have  already  said  that  the  so-called  canal  of  Bichat 
does  not  exist. 

It  has  been  stated  that  each  lateral  ventricle  is  divided,  both  in  its  direct  and  reflected 
portions,  by  a  circular  fissure  which  turns  round  the  optic  thalamus,  and  through  which  the 
pia  mater  becomes  continuous  with  the  choroid  plexus.  This  fissure  is  closed  by  blood- 
vessels, and  some  very  dense  cellular  tissue,  and  in  the  interior  of  the  ventricle  by  the  li- 
ning membrane,  which  is  firmly  attached  on  both  sides  of  the  fissure  to  the  adherent 
borders  of  the  corresponding  choroid  plexus.  It  cannot  be  admitted  that  it  passes  from 
one  side  of  the  fissure  to  the  other,  so  as  to  enclose  the  plexus. 

It  is  this  membrane  which  prevents  any  fluid  contained  in  the  ventricles  from  infiltra- 
ting into  the  sub-arachnoid  cellular  tissue  at  the  base  of  tlie  brain. 

The  very  frequent  coincidence  of  ventricular  dropsy  with  the  formation  of  false  mem- 
brane in  the  cellular  tissue  at  the  base  of  the  brain  shows  the  relation  between  that  tis- 
sue and  the  lining  membrane  of  the  ventricles,  but  by  no  means  establishes  the  exist- 
ence of  any  direct  communication  between  the  ventricular  cavities  and  the  cellular  tis- 
sue at  the  base  of  the  brain. 

The  Ventricular  Fluid. — The  existence  of  a  serous  fluid  in  the  ventricles  was  general- 
ly admitted  by  the  older  anatomists,  who  named  it  pituita,  and  considered  it  to  be  an 
excrementitious  fluid,  which  was  evacuated  through  the  nasal  fossae.  During  the  last 
century,  anatomists  were  so  convinced  of  its  existence  in  all  subjects,  that  they  regard- 
ed those  cases  in  which  it  was  not  found  as  exceptions  ;  a  recentissimis  cadaveribus  ahest 
nonnunquam,  says  Haller,  in  speaking  of  an  observation  made  by  Verduc  upon  the  brain 
after  death  by  decapitation.  But  the  anatomists  of  the  last  century  differed  from  the 
ancients  in  regarding  the  existence  of  fluid  in  the  ventricles  as  a  post-mortem  phenome- 
non, depending  on  the  condensation,  by  cold,  of  a  vapour  which,  in  their  opinion,  alone 
exists  in  the  ventricles  during  life.  This  vapour,  the  only  use  of  which,  according  to 
the  view  stated,  would  be  to  prevent  adhesion  of  the  opposite  walls  of  the  ventricles, 
was  compared  by  them  to  that  which  is  found  in  the  pleura,  pericardium,  and  peritoneum 
of  a  living  animal. 

The  experiments  of  M.  Magendie  have  proved  the  existence  of  a  ventricular  fluid  du- 
ring hfe  ;  and  farther,  that  it  may  flow  backward  and  forward  into  the  spinal  sub-arach- 
noid space,  through  the  opening  (,y,fig.  282)  in  the  lower  part  of  the  fourth  ventricle. 

The  quantity  of  fluid  in  the  several  spaces  found  in  the  cranial  cavity  is  extremely 
variable,  for  it  increases  or  diminishes  according  to  the  relative  bulk  of  the  brain  in  ref- 
erence to  the  osseous  case  of  the  scull. 

Having  thus  examined  the  brain  by  horizontal  sections,  made  at  different  heights 
from  the  convex  surface  towards  the  base,  it  is  important,  in  order  thoroughly  to  under- 
stand the  parts  we  have  described,  to  study  them  under  different  aspects,  either  by  means 
of  particular  sections,  or  by  the  aid  of  the  various  methods  adopted  by  different  anato- 
mists. 


Jt  Median  Vertical  Section  of  the  Brain. 

Upon  this  section  {fig.  282),  which  divides  the  brain  into  two  perfectly  similar  halves, 
p-    2g2  a  great  many  objects 

are  seen  :  and  first, 
the  optic  thalamus 
and  corpus  striatum, 
which  might  be  said 
to  form  the  central 
nucleus  or  root  of  the 
cc-ebrum. 

The  optic  thalamus 
is  now  seen  to  be 
smooth  and  free  on  its 
inner  surface,  where 
it  forms  the  lateral 
wall  (0  of  tlie  third 
ventricle  ;  it  is  con- 
vex and  free  above, 
where  it  forms  part 
of  the  floor  of  the  lat- 
eral ventricle,  and  it  is  also  free  below,  where  it  presents  to  our  notice  the  corpora  ge- 
niculata.  Behind,  it  is  continuous  with  the  tubercula  quadrigemina,  and  in  front  with 
the  corpus  striatum ;  on  the  outer  side  it  is  blended  with  the  corresponding  cerebral 


VERTICAL   SECTION    OF   THE   BEAIN.  749 

hemisphere,  and  below  it  is  deeply  notched  for  the  reception  of  the  corresponding  cere- 
bral peduncle. 

The  corpus  striatum  forms  a  concentric  curve  along  the  outer  side  of  the  opic  tliala- 
mus  ;  it  commences  in  front  by  a  large  pyriform  extremity,  duninishes  in  size  as  it  pro- 
ceeds backward,  and  terminates  in  a  very  narrow  gray  band,  which  turns  round  the  op- 
tic thalamus  as  far  as  the  termination  of  the  descending  cormi  of  the  lateral  ventricle, 
I  e.,  as  far  as  the  large  end  of  the  cornu  ammonis. 

The-  lateral  ventricle  forms  a  circular  or  elliptical  trench  around  this  central  nucleus, 
formed  by  the  thalamus  opticus  and  corpus  striatum  (see  fig.  278).  It  commences  in  the 
substance  of  the  anterior  lobe  of  the  cerebrum  {anterior  or  frontal  cornu),  mounts  up  upon 
the  corpus  striatum,  passes  horizontally  backward,  and,  becoming  widened,  divides  into 
two  prolongations  :  one  horizontal  (digital  cavity,  occipital  or  posterior  cornu),  which  dips 
into  the  substance  of  the  posterior  lobe,  and  terminates  near  the  surface  of  the  brain ; 
the  other  reflected,  which  runs  from  behind  forward,  and  terminates  behind  the  iissure  of 
Sylvius,  so  that  the  lateral  ventricle  would  describe  an  almost  complete  ellipse  if  it  were 
not  for  the  layer  of  cerebral  substance  which  forms  the  bottom  of  the  fissure  of  Sylvius, 
and  which  separates  the  commencement  (/)  from  the  termination  (Ji)  of  the  ventricle. 

Upon  the  longitudinal  section  is  also  seen  the  regular  curve  of  the  corpus  callosum  (e 
df,fig.  282),  which  nuis  around  the  central  nucleus.  The  unequal  thickness  of  the  dif- 
ferent parts  of  the  corpus  callosum,  its  reflection  in  front  so  as  to  embrace  the  anterior 
extremity  of  the  corpus  striatum,  its  posterior  enlarged  extremity  or  protuberance,  and 
its  continuity  with  the  fornix,  are  shown ;  and  farther,  it  is  seen  that  the  space  between 
the  corpus  callosum  and  the  central  nucleus  of  the  brain  constitutes  the  upper  part  of  the 
lateral  ventricle,  and  that  the  interval  between  the  cornu  ammonis  and  the  nucleus  con- 
stitutes its  reflected  portion. 

In  this  section  we  also  notice  the  septum  lucidum  (J,),  the  fornix  (A),  the  mammillary  tu- 
bercle (c),  the  tuber  cinereum,  the  gray  commissure  (i)  and  gray  mass  of  the  third  ven- 
tricle, the  infundibulum  (i),  the  optic  nerve  (2),  the  section  of  the  anterior  commissure 
(c),  also  that  of  the  posterior  commissure  {x),  and  the  peduncle  («)  of  the  pineal  gland  {p). 

The  longitudinal  section  also  shows  that  the  third  ventricle  is  formed  by  the  juxtapo- 
sition of  the  two  central  nuclei  of  the  cerebral  hemispheres  ;  that  these  hemispheres  are 
only  connected  to  each  other  by  the  corpus  callosum  and  the  commissures,  and  there- 
fore that  it  is  by  studying  these  parts  that  the  system  of  communicating  fibres  between 
the  two  hemispheres  is  displayed. 

It  is  moreover  seen  that  each  hemisphere  may  be  regarded  as  composed  of  a  white 
and  gray  covering  which  surrounds  a  central  nucleus.  And  it  is  between  the  general 
central  nucleus  and  the  hemispheres,  or,  rather,  between  the  fornix  and  its  prolongations 
on  the  one  hand,  and  the  optic  thalami  on  the  other  (as  at  s,fig.  281,  for  example),  that 
the  ventricles  would  communicate  with  the  exterior  if  the  ventricular  membrane  were 
not  firmly  attached  to  the  choroid  plexus  :  it  is  also  in  the  same  situation  that  the  exter- 
nal pia  mater  passes  into  the  internal. 

The  Central  Nucleus. — A  very  curious  preparation  may  be  very  easily  made  upon  this 
vertical  median  section,  to  show  the  central  nucleus  separated  from  the  other  parts.  If 
the  handle  of  a  scalpel  be  introduced  between  the  corpus  striatum  and  the  reflected  por- 
tion of  the  corpus  callosum,  it  will  be  found  that  the  ventricular  membrane  is  the  only 
means  of  connexion  between  them,  and  that  the  corpus  callosum  forms,  at  this  point,  a 
sort  of  outer  case  of  medullary  substance  for  the  corpus  striatum,  the  entire  anterior 
portion  of  which  may  be  exposed  without  breaking  through  any  connecting  fibres.  The 
anterior  part  of  the  corpus  striatum  znay  also  be  exposed  from  below,  that  is  to  say,  by 
dissecting  from  the  base  of  the  anterior  lobe  of  the  cerebrum  towards  the  lateral  ventri- 
cle ;  for  this  purpose,  the  handle  of  the  scalpel  must  be  inserted  along  a  curved  whitish 
line,  the  concavity  of  which  is  turned  forward,  and  which  limits  the  anterior  lobe  behind. 

The  corpus  striatum  can  be  completely  isolated  only  in  front  and  opposite  the  fissure 
of  Sylvius,  in  which  situation  it  is  covered  by  only  a  slight  thickness  of  cerebral  sub- 
stance, which  is  seen  to  consist  of  four  very  distinct  layers,  viz.,  the  external  gray  layer 
of  the  convolutions  ;  a  very  thin  white  layer ;  an  equally  thin  gray  layer  ;  and,  lastly, 
another  layer  of  medullary  substance. 

Transverse  Vertical  Sections. 
I  am  in  the  practice  of  making  five  transverse  sections  of  the  cerebrum  :  the  first,  im 
mediately  in  front  of  the  corpus  callosum ;  a  second  through  the  largest  part  of  the  cor- 
pora striata  ;  a  third  through  the  anterior  part  of  the  optic  thalami ;  a  fourth  through  the 
middle  of  the  thalami ;  and  a  fifth  through  the  occipital  portion  of  the  posterior  lobes.  I 
shall  not  here  enter  into  a  detailed  description  of  these  several  sections,  which  appeal 
to  me  to  convey  a  more  correct  idea  of  the  structure  of  the  brain  than  any  other  sec- 
tions, but  which  cannot  be  well  understood  without  figures.  They  disclose,  in  fact,  a 
medullary  centre  giving  ofll'  three  or  four  prolongations  of  white  substance,  which  con- 
stitute, in  their  turn,  the  medullary  centres  of  a  certain  number  of  convolutions  to  which 
they  are  distributed  ;  this  ramified  disposition  of  the  me;iullary  substance  warrants  the 


^W  NEUROLOGY. 

application  of  the  tern  arbor  vita  of  the  cerebrum  to  the  appearances  seen  upon  these  dif- 
ferent sections. 

The  most  interesting  of  these  sections  is  undoubtedly  that  which  passes  through  the 
cerebral  peduncles,  and  which  discloses  the  following  appearances  : 

Each  hemisphere  is  formed  by  a  medullary  centre,  which  gives  off  three  principal  pro- 
longations, around  which  all  the  convolutions  are  arranged,  and  are  thus  collected  into 
three  groups,  viz.,  a  superior,  an  external,  and  an  inferior  group  ;  the  last  of  these  is  con- 
nected with  the  medullary  centre  by  a  long  narrow  pedicle  which  corresponds  to  the 
white  matter  on  the  outside  of  the  corpus  striatum.  The  corpus  striatum  and  optic 
thalamus  are  situated  opposite  to  this  pedicle  or  prolongation  of  the  medullary  centre. 

The  medullary  centres  of  the  two  hemispheres  are  connected  together  by  the  corpus 
callosum,  which  forms  an  arch  with  the  concavity  directed  downward.  Moreover,  either 
the  section  of  the  septum  lucidum,  or  of  the  fornix,  is  seen  according  to  the  point  at  which 
the  knife  has  been  carried  through. 

The  transverse  section  through  the  corpora  striata  and  optic  thalami  deserves  special 
attention.  If  the  section  be  made  through  the  anterior  part  of  the  corpus  striatum,  and 
therefore  in  front  of  the  optic  thalamus,  the  former  body  presents  an  oval  gray  surface, 
dotted  with  white  points,  which  are  sections  of  medullary  fibres  ;  the  middle  of  this  oval 
surface  is  traversed  by  a  series  of  small,  parallel,  white  fasciculi,  which  are  sections  of 
the  medullary  bands  that  pass  through  the  corpus  striatum.  On  the  outer  side  of  the 
corpus  striatum  are  seen  distinctly  the  four  layers  formerly  mentioned  as  corresponding 
to  the  island  of  Reil.  The  white  layer  which  turns  round  the  outer  surface  of  the  corpus 
striatum  may  be  said  to  be  reflected  upward  to  form  the  septum  lucidum. 

Several  of  these  sections  appear  to  me  to  show  that  certain  white  fibres,  which  arise 
in  the  interior  of  the  corpora  striata,  pass  to  the  circumference  of  the  optic  thalami ;  or  it 
may  be  said  that  certain  white  fibres  arise  in  the  optic  thalami,  spread  out,  and  are  lost 
in  the  substance  of  the  corpora  striata,  beyond  which  it  is  impossible  to  trace  them. 
This  beautiful  section  suggested  to  M.  Foville*  some  ideas  respecting  the  structure  of 
the  brain,  to  which  I  shall  presently  have  occasion  to  refer. 

The  Section  of  Willis. 

Previously  to  the  time  of  Varolius  and  Willis,  anatomists  were  contented  with  making 
successive  horizontal  sections  of  the  brain  from  the  vertex  towards  the  base,  and  study- 
ing minutely  the  parts  thus  exposed ;  and  each  anatomist  believed  that  he  had  described 
different  objects  when  chance  presented  him  with  some  arrangement  that  had  not  been 
previously  described.  Willis  insisted  upon  the  necessity  of  carefully  removing  the  mem- 
branes from  the  surface  of  the  brain,  and  he  objected  to  the  usual  method  of  examining 
this  organ  by  making  sections,  which  destroy  the  connexions  between  its  different  parts  ; 
he  considered  the  brain  to  be  composed  of  farts  folded  upon  themselves,  collected  into  a 
globular  form,  and  connected  to  each  other  by  mutual  prolongations.  He  also  pointed 
out  the  importance  of  first  examining  the  brains  of  animals,  which  are  much  more  sim- 
ple than  the  brain  of  man,  the  size  and  complexity  of  which  render  its  study  one  of  great 
difficulty. 

After  having  made  these  judicious  remarks,  Willis  proceeds  to  describe  the  following 
mode  of  making  the  section  which  he  had  contrived,  for  the  purpose  of  unfolding  the 
cerebrum  and  opening  out  this  spheroidal  mass  into  a  flat  surface  :t 

Place  the  brain,  completely  stripped  of  its  membranes,  upon  its  convex  surface ;  turn 
forward  the  cerebellum  and  the  medulla  oblongata  ;  introduce  the  knife  into  the  fissure 
of  Sylvius,  and  carry  it  backward  as  far  as  the  digital  cavity ;  a  flap  will  thus  be  detached, 
comprising  all  the  lower  wall  of  the  descending  comu  of  the  lateral  ventricle.  Repeat 
this  section  on  the  opposite  side ;  and,  after  having  turned  backward  the  flaps  thus  form- 
ed, another  section  must  be  made  on  each  side  of  the  brain,  extending  from  behind  for- 
ward along  the  corpus  striatum,  on  a  level  with  the  outer  border  of  the  corpus  callosum, 
and  reaching  to  the  anterior  extremity  of  the  lateral  ventricle.  Turn  forward  the  inter- 
mediate flap,  which  wiU  comprise  the  cerebellum,  the  pons  Varolii  and  peduncles,  the 
optic  thalami,  and  the  corpora  striata. 

The  whole  of  the  interior  of  the  ventricle  is  thus  exposed,  so  that  we  can  examine  the 
lower  surface  of  the  corpus  callosum,  and  its  continuity  with  the  centrum  ovale  of  each 
hemisphere,  or  the  centrum  ovale  of  Vieussens  seen  from  below.  The  continuity  of  the 
fornix  with  the  comu  ammonis  is  also  well  displayed.  J 

*  Note  sur  la  Structure  du  Cerveau,  24e  Bulletin  de  la  Soci6t6  Anatomique. — {Nouvelle  Bihliolheque  Midi- 
cale. ) 

t  Tlie  brains  of  animals  being  much  less  complicated  than  that  of  man,  are  more  convenient  for  this  purpose. 
The  brain  of  a  sheep  thus  unfolded  is  represented  by  Willis  in  his  Cerebri  Analome,  fig.  vii. 

t  This  section,  which,  however,  like  all  similar  methods,  is  liable  to  the  objection  that  it  destroys  the  con- 
nexion of  parts,  suggested  toM.  Laurencet  the  idea  of  comparing  the  cerebral  mass  to  a  nervous  loop,  analo- 
gous to  the  loops  described  by  MM.  Prevost  and  Dumas  as  forming  the  terminations  of  the  nerves.  According 
to  this  view,  the  nervous  system  would  represent  an  elongated  ellipse,  one  end  of  which  would  be  represented 
bv  the  brain  and  the  other  by  the  extremities  of  all  the  nerves  ;  but  both  loops  are  equally  inadmissible. 


GALL    AND    SPURZHEIM  S    VIEWS    OF    THE   BEAIN.  '^?tfl 

General  Remarks  upon  the  Method  of  examining  the  Brain  by  successive 

Sections. 

The  method  of  examining  the  brain  by  successive  sections  has  been  carried  farthest 
by  Vicq  d'Azyr,  whose  beautiful  plates  are  entirely  devoted  to  the  demonstration  of  the 
objects  seen  upon  various  sections  of  the  brain  made  in  succession  either  from  below  or 
from  above.  This  method  unfolds  to  us  the  relative  disposition  of  the  gray  and  white 
substances,  shows  the  manner  in  which  the  ventricles  are  formed,  and  displays  to  us  the 
real  nature  of  parts  which,  in  consequence  of  their  projecting  and  being  free  at  some 
part  of  their  surface,  have  received  particular  names. 

But  this  mode  of  examining  the  brain  can  only  be  regarded  as  a  preUminary  means 
calculated  to  give  an  idea  of  this  organ  as  a  whole  ;  and  it  tends  to  perpetuate  the  er- 
roneous opinion  that  the  brain  is  a  pulpy  mass,  consisting  of  a  semi-fluid  substance,  and 
displaying  no  more  evidence  of  contrivance  in  its  structure  than  a  ball  of  wax. 

The  method  adopted  by  Varolius  and  Vieussens,  which  fell  into  disuse  after  the  pub- 
lication of  the  beautiful  work  of  Vicq  d'Azyr,  and  which  consisted  in  determining  the 
connexion  of  the  different  parts  of  the  brain,  has  been  revived  and  improved  by  Gall 
and  Spurzheim,  who  have  thus  opened  up  the  path  which  modern  anatomists  have  so 
eagerly  pursued. 

Methods  of  Varolius,  of  Vieussens,  and  of  Gall,  or  the  Examination  of  the 
Connexions  of  the  Different  Parts  of  the  Brain. 

Varolius  was  the  first  to  perceive  that  the  essential  point  in  the  study  of  the  brain  was 
to  ascertain  the  connexion  of  its  several  parts.  He  was  also  the  first  who  dissected  the 
brain  from  below,  and  who  specially  examined  its  connexion  with  the  spinal  cord ;  he 
described  the  spinal  cord  as  originating  from  the  brain,  not  opposite  the  foramen  mag- 
num, but  from  the  lower  part  of  the  cerebral  ventricles. 

Vieussens  traced  the  bundles  of  the  pyramids  through  the  pons  Varolii  to  the  pedun- 
cles of  the  brain,  and  followed  these  peduncles  through  the  optic  thalami  and  the  corpora 
striata  into  the  centrum  ovale,  which  is  named  after  him.  But  there  his  inquiries  ended, 
for,  according  to  him,  it  was  in  this  centre  that  the  linear  or  radiated  structure  termina- 
ted ;  and  his  preconceived  notion  of  a  nervous  centre  (centrum  ovale),  from  which,  with 
Varolius,  he  described  all  the  fibres  as  proceeding  downward,  prevented  him  from  carry- 
ing his  researches  farther. 

Gall  followed  up  the  investigations  of  Varolius  and  Vieussens,  but  instead  of  dissect- 
ing the  fibres  from  above  downward,  or  from  the  brain  towards  the  medulla,  he  traced 
them  from  below  upward,  or  from  the  medulla  towards  the  brain,  and  followed  them 
through  the  centrum  ovale  as  far  as  the  convolutions. 

The  method  adopted  by  Gall  in  order  to  separate  the  fibres  of  the  cerebrum  and  show 
their  connexions  was  to  scrape  them  with  the  handle  of  a  scalpel.  But,  from  the  nature 
of  this  proceeding,  only  those  white  fibres  can  be  conveniently  traced  which  pass  through 
gray  matter,  but  the  white  fibres  themselves  can  never  be  separated  from  each  other. 
Hardening  the  brain  in  strong  alcohol,  in  nitric  or  muriatic  acid,  or  by  boiling  it  in  oil,  or 
by  macerating,  or  boiling  it  in  a  solution  of  salt,  facilitates  the  separation  of  its  fibres  ; 
but,  as  the  results  obtained  in  these  modes  might  be  considered  as  purely  artificial,  the 
action  of  a  stream  of  water  is  preferable  to  any  of  them. 

The  results  obtained  by  acting  on  the  brain  by  streams  of  water  fully  confirm  those 
which  are  arrived  at  by  the  examination  of  the  hardened  brain. 

Again,  the  anatomy  of  the  fcEtal  brain  and  comparative  anatomy  have  also  aided  in 
throwing  light  upon  the  connexion  between  the  different  parts  of  the  brain. 

As  the  works  of  Gall  were  the  commencement,  if  not  the  foundation,  of  all  that  has 
since  been  done,  I  have  thought  it  necessary  to  give  a  brief  summary  of  his  views  re- 
garding the  structure  of  the  brain  ;  and  as  a  knowledge  of  its  structure  consists  in  a  great 
measure  in  that  of  its  connexions  with  the  cerebellum  and  spinal  cord,  the  examination 
of  these  two  subjects  cannot  properly  be  separated. 

Gall  and  Spurzheim' s  Views  of  the  Structure  of  the  Brain, 
Gall  and  Spurzheim  commence  by  stating,  1.  That  as  the  brain  consists  of  several 
departments,  the  functions  of  which  are  totally  different,  there  are  several  primitive  fas- 
ciculi which,  by  their  development,  assist  in  the  formation  of  that  organ.  2.  That  these 
fasciculi  are  composed  of  medullary  fibres  arising  successively  from  the  gray  matter, 
which,  with  Vicq  d'Azyr,  they  regard  as  the  matrix  or  generator  of  the  white  substance. 
3.  That  there  exist  in  the  brain  a  formative  system  of  fibres,  or  a  formative  apparatus, 
and  systems  of  uniting  fibres,  called  commissures.  In  the  first,  or  formative  system, 
Gall  describes  four  primitive  fasciculi ;  namely,  the  anterior  pyramids,  the  posterior 
pyramids,  the  olivary  fasciculi,  the  longitudinal  fasciculi,  which  assist  in  forming  the  fourth 
ventricle,  and  some  others  which  are  yet  imperfectly  understood.* 

*  It  win  be  observed  that  Gall's  fundamental  statements  are  hypothetical :  that  the  brain  is  developed  from 
certain  primitive  fasciculi,  that  there  is  a  successive  increase  of  these  fasciculi  from  below  upward,  and  that 


752 


NEUROLOGY. 


Formative  Sijstem  of  Fibres. — The  anterior  pyramidal  fasciculi  decussate  at  their  origin, 
but  the  other  fasciculi  arise  on  the  same  side  as  the  hemisphere  to  which  they  belong. 

The  anterior  pyramidal  fasciculi  {h',figs.  273,  274)  are  re-enforced  as  they  pass  through 
the  pons  Varolii  (m),  which  is  tljerefore,  according  to  Gall's  view,  a  ganglion,  named  by 
him  the  ganglion  of  the  anterior  pyramidal  fasciculi ;  these  pyramidal  fasciculi  constitute 
the  cerebral  peduncles  {x,  fig.  283),  and  diverge  (y  y')  so  as  to  enter  the  inferior,  ante- 
rior, and  external  (i  and  m,  fig.  284)  convolutions  of  the  anterior  and  middle  lobes. 

Gall,  in  his  beautiful  plate.  No.  V.,  shows  the  expansion  of  the  fibres  of  the  peduncles, 
their  distribution,  their  unequal  lengths,  and  the  manner  in  which  their  expanded  ex- 
tremities are  covered  with  gray  matter  to  form  the  convolutions. 

It  still  i-emains  to  determine  how  the  superior  convolutions  and  those  of  the  posterior 
lobe  are  formed  :  the  following  are  the  statements  of  Gall  on  this  point : 

The  olivary  bodies  of  the  medulla  oblongata  are  nothing  more  than  ganglia,  from  each 
of  which  a  very  strong  bundle,  the  olivary  fasciculus  (see  p.  708),  emerges,  and  ascend- 
ing behind  the  pons,  where  it  is  considerably  re-enforced,  passes  through  the  gray  mat- 
ter which  lies  upon  the  white  fibres  of  the  cerebral  peduncle,  where  it  again  receives 
some  additional  fibres  ;  this  gray  matter  constitutes  a  rather  firm  ganglion  on  each  side  ; 
these  are  the  optic  thalami,  which,  according  to  Gall,  do  not  assist  in  the  formation  of 
the  optic  nerves,  and  bear  no  proportion  to  them  in  size. 

The  olivary  fascicuh,  which  are  divided  into  very  delicate  filaments  in  traversing  the 
optic  thalamus,  are  again  collected  together  as  they  emerge  from  its  upper  border. 
They  then  pass  through  a  thick  mass  of  gray  matter,  the  corpus  striatum,  half  of  which 
projects  into  the  ventricular  cavity,  while  the  other  half  is  surrounded  by  the  convolu- 
tions of  the  island  of  Reil.  The  radiated  fasciculi  {k,  fig.  284)  are  again  re-enforced  in 
traversing  the  corpus  striatum,  which  is  regarded  by  Gall  as  another  ganglion,  and  are 
then  sufficient  to  form  all  the  posterior  convolutions,  and  also  those  which  are  situated 
along  the  upper  border  of  each  hemisphere,  in  the  median  line  (A  h  h). 

It  therefore  follows,  according  Gall,  that  the  convolutions  are  nothing  more  than  the 


Fig.  283. 


perfecting  of  all  the  preceding  structures,  which 
should  be  regarded  as  preparatory  systems  of  fibres 
destined  to  form  a  whole. 

Uniting  System  of  Fibres  or  Commissures. — Even 
the  oldest  anatomists  regarded  the  corpus  callo- 
sum  as  the  connecting  medium  between  the  two 
hemispheres  ;  Vicq  d'Azyr,  who  described  several 
other  commissures  besides  the  corpus  callosum, 
regarded  them  as  intended  to  establish  sympathet- 
ic connexions  between  the  different  parts  of  the 
brain.  Gall,  taking  a  more  comprehensive  view 
of  this  subject,  attempted  to  determine  what  parts 
of  the  brain  were  connected  by  this  means,  and  to 
discover  the  general  law  which  governs  the  ar- 
rangement of  the  commissures,  wliich  he  believ- 
ed to  be  formed  by  a  system  of  fibres  and  bundles, 
named  by  him  faisceaux  rentrans  ou  convergent. 

We  have  seen  that  Gall  traces  the  pyramidal 
and  olivary  fasciculi  to  the  gray  matter  of  the  con- 
volutions. According  to  him,  all  the  extremities  of 
the  medullary  fibres  penetrate  the  gray  matter, 
which  is  therefore  whiter  internally  than  on  the 
surface.  Gall  acknowledges  that  he  has  not  been 
able  to  determine  their  ultimate  distribution ;  he 
does  not  know  whether  they  terminate  in  the  gray 
matter,  or  turn  back  again  towards  the  interior. 
Nevertheless,  he  considers  it  very  probable  that 
new  medullary  filaments  originate  in  this  gray  lay- 
er, and  that  there  is  thus  produced  a  system  of  fibres 
which  re-enforces  the  preceding  one,  and  is  connected 
with  it  internally.* 

the  graysubstance  is  the  matrix  of  the  white,  are  so  many  suppositions.  Of  the  primitive  fasciculi,  the  anterior 
pyramids  alone  are  well  defined  ;  the  inaccuracy  in  the  representation  of  the  posterior  pyramids  disfigures  his 
sixth  plate. 

*  Nothing  certain  appears  likely  to  arise  from  this  proposition,  and  yet  Gall  immediately  adds  (p.  202),  "  It 
is  certain  that  the  existence  of  two  systems  of  fibres  in  the  brain  can  be  distinctly  demonstrated,  and  that  the 
converging  system  contains  more  fibres  and  stronger  fasciculi  than  the  radiating  system."  On  seeking  for 
his  proofs,  we  find  that  he  infers  that  converging  filires  must  necessarily  exist,  from  the  disproportion  between 
the  white  matter  of  the  hemispheres  and  the  fibres  which  come  to  them  from  the  fasciculi  of  origin.  "The  con- 
verging fibres,'"  says  he, "  at  the  bottom  of  all  the  convolutions,  are  see«  to  enter  between  the  diverging  fibres, 
and  interlace  with  them."  It  is  very  evident,  from  an  examination  of  the  proofs  adduced  by  Gall  in  support 
of  the  existence  of  converging  fibres,  that  the  distinction  between  the  converging  and  diverging  fibres  is  purely 
hypothetical. 


GENERAL    IDEA   OF   THE   BRAIN. 

According  to  Gall,  the  commissures  are,  the  corpus  callosum,  the  fornix,  and  the  ante- 
"ior  and  posterior  commissures. 

The  corpus  callosum  {fd  e,Jig.  283)  is  intended  to  unite  the  convolutions  of  the  two 
hemispheres.  Its  anterior  reflected  portion  unites  the  inferior  convolutions  of  the  two 
anterior  lobes  (fp  a  a).  The  enlarged  posterior  extremity  (e)  receives  the  fibres  (s  «) 
of  the  posterior  convolutions  (b)  and  the  middle  portion  of  those  of  the  middle  convolu- 
tions (c). 

The  anterior  commissure,  which  can  be  so  easily  traced  {m)  through  the  corpus  stria- 
tum into  the  convolution  of  the  sphenoidal  extremity  of  the  posterior  [middle]  lobe,  is 
regarded  by  Gall  as  the  means  of  connecting  certain  corresponding  convolutions  in  the 
sphenoidal  portions  of  the  two  posterior  [middle]  lobes. 

The  posterior  commissure,  which  is  lost  in  the  substance  of  the  optic  thalami,  and 
which  is  much  smaller  than  the  anterior,  fulfils  the  same  purpose  for  those  bodies. 

The  posterior  pillars  (k)  of  the  fornix  are  regarded  by  Gall  as  forming  a  commissure 
for  the  posterior  convolutions  of  the  two  middle  lobes.  The  fornix  appears  to  him  to 
result  from  the  connexion  of  these  parts,  and  he  considers  the  interlacement  called  the 
lyra  to  be  composed  of  the  connecting  filaments.  His  error  here  is  evident,  for  the  for- 
nix results  from  the  juxtaposition  of  two  medullary  cords.  The  fornix  may  be  regarded 
as  an  antero-posterior  (A  h),  but  not  as  a  transverse  commissure. 

The  Ventricles  and  Convolutions. — The  formation  of  ventricles  is  considered  by  Gall  to 
be  the  necessary  result  of  the  divergence  of  some  fasciculi  and  the  convergence  of  others. 

His  description  of  the  convolutions  is  entirely  new,  and  one  cannot  but  regret  that  it 
should  be  disfigured  by  the  hypothesis  of  converging  and  diverging  fibres.  The  follow- 
ing is  his  mode  of  describing  these  parts,  which  he  regards  as  the  completion  and  final 
object  of  the  organization  of  the  brain,  and  as  performing  the  nlbst  elevated  functions. 

Gall  admits  two  layers  in  each  convolution ;  and  he  finds  that  these  two  layers  can 
always  be  readily  separated,  but  only  in  the  median  line.  He  successfully  proves,  in  op- 
position  to  the  commission  of  the  Institute,  that  the  convolutions  are  not  composed  of  a 
white,  soft,  and  pulpy  matter,  resembling  pomade  or  jelly,  but  that  they  have  a  fibrous 
or  linear  structure.* 

Unfolding  of  the  Cerebrum. — The  idea  of  unfolding  the  brain,  which  is  nothing  more 
than  opening  out  the  convolutions,  was  derived  by  Gall  from  his  view  of  the  structure  of 
the  convolutions,  which  he  regarded  as  formed  of  two  layers  united  by  very  delicate  cel- 
lular tissue.  It  was  eilso  suggested  to  him  by  the  examination  of  hydrocephalic  brains, 
in  which  he  conceived  there  was  no  disorganization,  but  merely  an  unfolding  of  the  con- 
volutions. 'Die  following  is  his  method  of  unfolding  the  brain  :  after  having  very  care- 
fully removed  the  meninges,  he  introduced  his  fingers  into  the  great  transverse  fissure 
between  the  optic  thalamus  and  the  hippocampus  major,  and  thus  penetrated  into  the 
lateral  ventricles  :  he  then  pressed  gently  against  the  outside  of  the  ventricles  ;  he  broke 
down  the  white  matter  of  the  hemispheres  until  he  reached  the  base  of  the  convolutions, 
which  then  necessarily  became  unfolded,  so  as  to  be  moulded  upon  the  back  of  his  hand  ; 
the  astonished  spectators  would  have  wondered  less  if  they  had  seen  the  lacerations  ne- 
cessary to  produce  this  result. 

The  unfolding  of  the  brain  is  impossible  if  Gall's  views  be  correct ;  for,  according  to 
him,  the  white  fibres  of  the  brain  are  not  all  of  equal  length,  and  those  which  correspond 
to  the  anfractuosities  are  much  shorter  than  those  corresponding  to  the  convolutions  ; 
besides,  I  am  convinced  that,  in  hydrocephalus,  the  convolutions  are  not  unfolded,  but 
are  atrophied,  flattened,  and  compressed  against  each  other. 

Such  are  the  principal  ideas  of  Gall  regarding  the  structure  of  the  brain,  t  His  system 
undoubtedly  contains  numerous  errors  and  imperfections ;  but,  nevertheless,  it  has  estab- 
lished a  new  era  in  the  study  of  the  anatomy  of  this  organ. 

General  Idea  of  the  Brain. 

1.  The  decussation  of  the  pyramidal  fasciculi  of  the  medulla  oblongata,  their  passage 
through  the  pons  Varolii,  their  continuity  with  the  cerebral  peduncles,  of  which  they 
form  the  lower  portion,  their  passage  through  the  optic  thalamus,  and  their  expansion 
within  the  corpora  striata  {k,  fig.  284),  through  which  they  may  be  traced  (A  h  h)  as  far 
as  the  convolutions,  are  incontestable  facts. 

2.  Again :  it  is  no  less  certain  that  the  fascicuU  of  re-enforcement  of  the  medulla  are 

*  See  note,  p.  75S. 

t  The  following  is  the  completion  of  these  ideas  :  1.  As  the  peripheral  extremities  of  the  nerves  expand  in 
all  the  organs  of  our  body  to  form  an  immense  surface  (and  of  this  expansion  the  retina  is  an  excellent  exam- 
ple), so  do  the  primitive  fasciculi  of  the  brain,  after  being  re-enforced  in  their  passage  through  the  different 
masses  of  gray  substance,  finally  expand  in  the  convolutions,  and  receive  a  covering  of  gray  matter.  2.  There 
are  as  many  particular  systems  as  there  are  different  functions,  but  they  are  all  connected  together  by  anas- 
tomoses. 3.  The  nervous  system  is  double,  but  is  united  into  one  whole  by  the  commissures.  4.  There  is 
not,  and  there  cannot  be,  any  common  centre  of  all  the  sensations,  thoughts,  and  volitions.  5.  Personal  unity 
will  always  remain  a  mystery. 

Each  of  these  propositions  might  form  the  subject  of  ample  commentary.  I  will  merely  remark  the  incon- 
gruity between  the  acknowledged  fact  of  personal  unity,  and  the  singular  proposition  that  there  neither  i^ 
nor  can  be,  any  common  centre  of  all  the  sensations,  tlioughts,  and  volitions. 

5C 


754 


NEUROLOGY. 


prolonged  above  tliB'JiSftS into  the  cerebral  peduncles,  of  which  they  form  the  upper  poi- 
tion  {x,  Jig.  283),  and  become  continuous,  without  any  line  of  demarcation,  with  the  optic 
thalamus.  Do  these  fasciculi  decussate  1  They  remain  distinct  until  they  reach  oppo- 
site the  pons,  behind  the  tubercula  quadrigemina,  where  they  unite  ;  they  appear  to  me 
to  decussate,  but  not  so  evidently  as  the  anterior  pyramids,  and  I  cannot  venture  to  state 
this  positively. 

3.  Fasciculi  of  white  fibres  radiate  in  all  directions  (y  y',Jig.  283)  from  every  part  of 

Fig.  284.  the  surface  of  the  optic 

thalamus  (g  g),  excepting 
its  inner  side,  which  is 
free,  and  corresponds  to 
the  third  ventricle ;  the  an- 
terior of  these  fibres  pass 
directly  forward,  the  mid- 
dle fibres  outward,  and  the 
posterior  fibres  backward, 
forming  the  radiating 
crown  of  Reil  (k,fig.  284). 
As  these  radiating  fibres 
emerge  from  the  optic  tha- 
lamus, they  are  bound 
down,  as  it  were,  by  cer- 
tain white  curved  fibres, 
which  constitute  the  tsenia  semicircularis. 

4.  All  the  white  fasciculi  of  the  corpora  striata,  excepting  those  which  are  continuous 
with  the  anterior  pyramids,  proceed  from  the  optic  thalami.  Some  of  them  appear  to 
me  to  terminate  in  the  corpora  striata  in  the  form  of  extremely  delicate  filaments,  but 
the  greater  number  pass  through  the  corpora  striata  without  either  increase  or  diminu- 
tion, and  then  pass  into  the  hemispheres.  The  corpora  striata  of  Willis  are,  therefore, 
nothing  more  than  gray  pulpy  masses,  which  are  traversed  both  by  the  white  fibres  ra- 
diating from  the  circumference  of  the  optic  thalami,  and  by  those  which  are  derived  from 
the  anterior  pyramids.  The  gray  matter  is  not  arranged  in  alternate  linear  stris  with 
the  Avhite  substance.  So  far  from  thinking,  with  Reil,  Gall,  and  Tiedemann,  that  the 
fibres  which  emerge  from  the  corpora  striata  are  much  more  numerous  than  those  which 
enter  it,  I  have  been  led  to  a  precisely  opposite  conclusion,  namely,  that  a  certain  num- 
ber of  fibres,  proceeding  from  the  optic  thalami,  terminate  in  the  interior  of  the  corpora 
striata,  the  gray  matter  of  which,  in  reference  to  these  fibres,  represents  the  gray  sub- 
stance in  the  convolutions. 

5.  From  the  anatomical  fact  that  a  certain  number  of  white  fibres  terminate  in  the 
corpora  striata,  and  also  from  the  size  of  those  bodies  being  in  some  animals  inversely 
proportioned  to  that  of  the  hemispheres,  it  appears  to  me  to  follow  that  the  corpora  stri- 
ata may  be  regarded  as  internal  convolutions,  in  which  a  certain  number  of  medullary 
fibres  terminate.* 

6.  It  is  extremely  easy,  by  means  of  a  stream  of  water,  to  separate,  and,  as  it  were, 
enucleate  the  corpus  striatum  from  the  sort  of  shell  formed  for  it  by  the  cerebrum  oppo- 
site the  fissure  of  Sylvius.  The  corpus  striatum  is  only  connected  with  the  cerebrum 
by  the  radiating  fibres  which  emerge  from  its  upper  circumference  near  the  corpus  cal- 
losum. 

The  optic  thalamus  and  its  fasciculus  of  origin  present  no  trace  of  a  linear  structure. 
Nor  can  we  discover  in  it  the  concentric  layers  admitted  by  Herbert  Mayo.  With  a  lit- 
tle attention,  certain  extremely  delicate  white  filaments  are  seen  in  the  optic  thalamus, 
which  cannot  be  separated,  on  account  of  their  tenuity  and  the  adhesion  of  the  surrounding 
tissue  to  them.  If  the  term  ganglion  be  applicable  to  any  part  of  the  cerebrum,  it  cer- 
tainly is  so  to  the  optic  thalamus  ;  for  a  nervous  ganglion  is  nothing  more  than  a  pecu- 
liar apparatus  in  which  nervous  filaments  become  separated  and  spread  out,  in  order  to 
enter  into  new  combinations.  We  must  agree  with  Reil  and  Tiedemann  in  regarding 
the  optic  thalami  as  appendages  of  the  cerebral  peduncles  :  Tiedemann  calls  them  the 
enlargements  of  the  cerebral  ■peduncles. 

7.  The  essential  points  to  be  made  out  in  the  structure  of  the  cerebrum  are  the  ulti- 
mate course  of  the  fibres  radiating  from  the  optic  thalami  and  corpora  striata,  and  the 
relations  of  those  fibres  with  the  convolutions  of  the  brain  and  the  corpus  callosum.  I 
by  no  means  agree  with  Reil  in  thinking  that  we  must  not  attach  so  much  importance  to 
the  continuity  of  fibres  in  the  cerebrum,  and  that  their  contiguity  is  a  sufficient  guide  to 
its  anatomy :  on  the  contrary,  I  regard  the  determination  of  their  continuity  as  the  key 
to  the  structure  of  this  organ. 

8.  There  is  no  median  raphe  in  the  corpus  callosum,  the  right  half  of  its  transverse 
fasciculi  being  continued  into  the  left  half,  without  any  line  of  demarcation. 

*  In  several  cases  of  chronic  hydrocephalus,  in  which  the  hemispheres  were  reduced  to  a  very  thin  lamina. 
I  have  found  the  optic  thalami  atrophied,  and  the  corpora  striata  of  enormous  size. 


GENERAL    IDEA    OF    THE    BRAIN.  755 

9.  It  appears,  at  first  sight,  that  the  fibres  of  the  corpus  callosum  {edf,fig.  284),  and 
the  white  radiating  fibres  (k),  which  emerge  from  the  optic  thalami  and  corpora  striata, 
decussate  (as  at  g) ;  but  on  separating  the  fibres  of  the  cerebrum,  either  after  it  has  been 
hardened  in  alcohol  or  by  the  action  of  a  stream  of  water,  it  is  most  distinctly  shown 
that  these  two  sets  of  fibres  are  continuous. 

10.  Again  :  the  continuity  of  the  fibres  of  the  corpus  callosum  with  those  of  the  hem- 
ispheres is  no  less  evident ;  the  middle  fibres  {,s,fig.  283)  of  the  hemispheres  are  seen 
to  pass  transversely  inward,  the  anterior  fibres  (a  p)  backward,  the  posterior  fibres  («) 
forward,  and  the  inferior  fibres  to  bend  and  turn  upward,  to  become  continuous  with  the 
corpus  callosum. 

I  have  in  vain  endeavoured  to  determine  by  actual  dissection  whether  there  is  a  de- 
cussation of  the  fibres  of  the  corpus  callosum  itself;  I  still  entertain  many  doubts  regard- 
ing this  subject ;  we  shall  presently  find,  when  speaking  of  the  development  of  the  brain, 
that  the  corpus  callosum  does  not  appear  until  after  the  hemispheres ;  and  that  compara- 
tive anatomy,  by  showing  that  the  corpus  callosum  does  not  exist  in  the  three  lower 
classes  of  vertebrate  animals,  is  opposed  to  the  idea  that  the  hemispheres  are  composed 
of  certain  fibres  which  decussate  in  the  corpus  callosum. 

11.  The  doctrine  of  converging  and  diverging  fibres,  advanced  by  Gall  and  Reil,*  can- 
not explain  the  continuity  of  the  fibres  of  the  corpus  callosum  with  the  radiating  fibres 
of  the  corpora  striata  and  optic  thalami. 

Tiedemann,  from  his  researches  into  the  anatomy  of  the  foetal  brain,  states  that  the 
corpus  callosum  is  formed  by  the  reunion  of  the  fibres  of  the  cerebral  peduncles  after 
they  have  expanded  to  form  the  hemispheres.  He  says  that  he  has  traced  the  fibres  of 
the  peduncles  as  far  as  the  median  line  of  the  corpus  callosum,  where  those  of  one  side 
unite  and  are  blended  with  those  of  the  other  ;  but  a  careful  examination  of  the  cere- 
brum, either  by  means  of  a  stream  of  water,  or  by  hardening  it,  shows  that  the  fibres  of 
the  corpus  callosum  terminate  in  the  convolutions,  without  presenting  any  sort  of  re 
flection,  or  forming  any  median  raphe. 

12.  The  dissections  of  M.  Foville  seem  to  establish  the  continuity  of  the  coi-pus  callo- 
sum both  with  the  radiating  fibres  of  the  corpora  striata  and  with  the  fibres  of  the  hem- 
ispheres. According  to  his  dissections,  which  consist  essentially  in  transverse  vertical 
sections,  the  radiating  fibres  of  the  optic  thalami  and  corpora  striata  divide  immediately 
into  three  very  distinct  superimposed  planes. 

The^rsf  or  superior  plane  is  reflected  upward  and  then  inward,  so  as  to  describe  a 
curve  with  its  convexity  turned  outward,  passes  horizontally  inward  to  form  the  corpus 
callosum,  and  unites  with  the  corresponding  fibres  of  the  opposite  side. 

The  second  or  middle  plane,  the  plane  of  the  hemisphere,  ascends  parallel  to  the  corpus 
callosum  up  to  the  point  where  the  fibres  of  that  body  are  reflected  inward ;  it  then  con- 
tinues in  an  almost  vertical  direction,  and  thus  reaches  the  gray  matter. 

The  third  or  inferior  plane,  much  smaller  than  either  of  the  preceding,  is  extremely 
thin,  and  follows  a  very  different  course :  immediately  after  emerging  from  the  common 
place  of  origin,  it  descends  on  the  outer  side  of  the  corpus  striatum,  turns  round  its  low- 
er part,  approaches  the  median  line,  and  then  mounts  upward,  in  contact  with  the  cor- 
responding plane  of  the  opposite  side,  through  the  middle  of  the  ventricles,  where  the 
two  juxtaposed  planes  form  the  septum  lucidum. 

13.  Is  the  fornix  an  antero-posterior  commissure  1  In  support  of  this  opinion,  I  may 
state,  that  I  have  seen  the  right  half  of  the  fornix  atrophied  in  a  case  of  destruction  of 
the  convolutions  corresponding  to  the  tentorium  cerebelli. 

14.  The  anterior  commissure  (m,  fig.  283),  which  was  regarded  by  Willis  as  the  com- 
missure of  the  corpora  striata,  and  by  Reil  as  intended  to  connect  the  anterior  convolu- 
tions of  the  middle  lobe  and  some  convolutions  situated  at  the  bottom  of  the  fissure  of 
Sylvius,  belongs  to  the  system  of  converging  fibres,  according  to  Gall,  who  describes 
them  as  commencing  in  the  gray  matter  of  the  convolutions.  According  to  Tiedemann, 
this  commissure  is  a  continuation  of  the  cerebral  peduncles,  each  of  which,  after  having 
traversed  the  corpora  striata,  expands  in  the  corresponding  hemispheres,  and  gives  ofl' 
several  radiating  fasciculi  which  incline  forward  and  inward,  are  collected  together  into 
a  cord,  and  unite  with  those  of  the  opposite  side ;  the  anterior  commissure,  therefore 
according  to  this  view,  is  a  bond  of  union  between  the  radiating  fibres  of  the  cerebra 
peduncles  and  those  of  the  right  and  left  middle  lobes  of  the  brain.  Chaussier  had  al- 
ready derived  the  fibres  of  this  commissure  from  the  cerebral  peduncles.  All  that  is 
certainly  known  regarding  it  is,  that  the  cord  of  which  it  consists  passes  through  the  an- 
terior portion  of  each  corpus  striatum,  and  expands  in  the  anterior  and  inferior  convolu- 
tions of  the  sphenoidal  horn  of  the  posterior  [middle]  lobes,  behind  the  fissure  of  Sylvius. 

15.  The  cornu  ammonis  is  formed  by  the  reflection  of  the  lower  part  of  the  hemi- 
sphere :  the  white  laminae  which  cover  it,  the  corpus  fimbriatum  along  its  border,  and  the 

*  The  following  is  Reil's  statement  on  this  subject:  ;'  Both  of  these  two  systems  of  fibres  spread  out  into 
rays  and  meet  each  other  ;  the  cerebral  peduncles  ascend  from  below,  and  eipand  into  the  form  of  an  invert- 
ed cone  ;  the  system  of  the  corpus  callosum,  on  the  contrary,  comes  from  above,  and  its  fibres  insinuate  them 
selves  between  the  preceding  ones  (see  g,fig.  284),  and  form,  as  it  were,  tlie  lid  of  the  cup." 


756  NEUROLOGY. 

fornix,  constitute  but  one  system,  which  evidently  belongs  to  the  antero-postenor  com- 
missures. 

16.  Each  convolution  is  composed  of  two  precisely  similar  semi-convolutions ;  the 
two  halves,  which  can  be  readily  separated  by  a  stream  of  water,  may  be  decomposed 
into  a  considerable  number  of  striated  lamellae,  arranged  like  a  fan,  the  margin  of  which 
would  correspond  to  the  free  border  of  the  convolution,  and  the  narrow  end  to  the  ad- 
herent border ;  these  striated  lamellae  are  separated  from  each  other  by  vascular  fila- 
ments ;  their  number  seems  to  vary  in  different  subjects  ;  they  seem,  moreover,  to  be 
altogether  independent  of  each  other.  The  stream  of  water  detaches  a  corresponding 
layer  of  gray  matter  with  each  white  lamella.  This  layer  of  gray  matter  is  also  striated, 
and  appears  to  be  composed  of  fibres  implanted  upon  the  white  matter,  as  Mr.  Herbert 
Mayo  has  very  clearly  pointed  out. 

1 7.  It  follows,  therefore,  that  in  the  convolutions,  a  lamellar  striated  arrangement  suc- 
ceeds to  the  fibrous  or  linear  arrangement  of  the  medullary  centres  and  radiating  fibres 
of  each  hemisphere.* 

These  lamellae  are  evidently  continuous  with  the  radiating  fibres  of  the  corpus  striatum 
and  optic  thalamus.  Still,  there  is  in  each  convolution  a  proper  lamella,  the  continuity 
of  which  with  the  radiating  system  of  the  hemispheres  I  have  not  been  able  to  trace. 

18.  We  should  not  regard  the  convolutions  as  so  many  sinuous  eminences  separated 
by  the  anfractuosities  :  on  the  contrary,  the  bottom  of  the  anfractuosity  forms  the  mid- 
dle part  or  fold  of  a  layer  of  white  and  gray  matter,  half  of  which  layer  belongs  to  one 
convolution  and  half  to  the  next  convolution  (n  n,  fig.  284).  Now  it  is  these  white  lamel- 
lae which  line  the  gray  matter  that  appear  to  be  proper  to  each  convolution ;  and  be- 
tween these  proper  lamellae  are  situated  the  white  striated  plates  that  are  continuous 
with  the  radiating  fibres  of  the  hemispheres,t  which  fibres  are  not  arranged  in  lamellae, 
but  merely  in  lines. 

It  follows  from  all  that  has  been  stated,  that  there  are  yet  several  deficiencies  in  our 
knowledge  of  the  anatomy  of  the  brain,  which  prevent  us  from  forming  a  complete  idea 
of  its  structure. 

Development  of  the  Cerebrum.^ 

In  the  early  periods  of  foetal  life,  about  the  end  of  the  second  month,  the  hemispheres 
are  represented  by  a  very  thin  membrane,  which  is  turned  backward  and  inward,  so  as 
to  cover  the  corpora  striata. 

The  optic  thalami,  which  appear  as  enlargements  of  the  cerebral  peduncles,  the  tuber- 
cula  quadrigemina,  and  the  cerebellum,  are  completely  exposed.  The  corpus  callosum 
does  not  yet  exist.  The  human  brain  may,  then,  be  considered  as  resembling  the  brain 
of  fishes. 

Towards  the  end  of  the  third  month,  the  membrane  of  the  hemispheres  has  acquired 
a  farther  development,  and  covers  not  only  the  corpora  striata,  but  also  the  optic  thalami. 
The  tubercula  quadrigemina  and  the  cerebellum  are  still  exposed.  The  anterior  lobes 
only  of  the  cerebrum  are  formed.  The  posterior  lobes  seem  to  be  merely  appendages. 
The  hemispheres,  then,  constitute  at  this  period  a  membranous  sac,  which  is  open  on  the 
inner  side  and  behind,  and  may  be  regarded  as  representing  the  brain  of  reptiles.    The 

*  M.  Leuret  has  been  led  to  the  same  conclusion  regarding  the  lamellar  structure  of  the  convolutions,  by 
studying  the  brain  hardened  by  boiling  it  in  a  solution  of  salt. 

t  iVIr.  Herbert  Mayo  (a  series  of  engravings  intended  to  illustrate  the  structure  of  the  brain  and  spinal 
cord  in  man,  1825),  who  has  followed  the  example  of  Reil,  in  examining  the  brain  with  so  much  care  after  it 
hjis  been  hardened  in  alcohol,  admits  the  existence  of  three  sorts  of  fibres  in  each  convolution,  viz.,  fibres 
■which  pass  from  one  convolution  to  the  next  (u  Uyfig.  283),  and  also  to  more  distinct  convolutions  ;  fibres  which 
come  from  the  commissures  (s  s  p)  ;  and  fibres  derived  from  the  spinal  cord.  According  to  this  anatomist,  the 
fibres  which  pass  from  one  convolution  to  another  constitute  tlje  principal  part  of  each  convolution  ;  the  othej 
white  fibres  which  form  the  centre  of  each  convolution  are  derived  partly  from  the  commissures  and  partly 
from  the  optic  thalami  and  corpora  striata. 

According  to  him,  the  white  fibres  (/  q)  which  form  the  inferior  layer  of  the  cerebral  peduncles  radiate  in 
the  substance  of  the  cerebrum,  and  constitute  its  anterior  and  middle  fibres.  The  fibres  proceeding  from  the 
optic  thalami  form  the  posterior  cerebral  fibres  (y).  There  is,  he  affirms,  one  point  in  which  the  radiating 
fibres  evidently  decussate  with  the  fibres  from  tlie  great  commissure  of  the  brain  or  corpus  callosum  (as  at  g, 
fig.  284).     The  posterior  radiating  fibres  do  not  present  this  decussation. 

The  two  most  remarkable  fasciculi  of  communication  between  the  convolutions  are  the  following :  that 
which  occupies  the  bottom  of  the  fissure  of  Sylvius  (I,  fig.  283  ;  m,fig.  284),  and  which  unites  the  convolu- 
tions of  the  anterior  and  posterior  lobes  ;  and  that  (  p  p,fig.  283  ;  I,  fig.  284)  which  runs  above  the  corpus  cal- 
fosum,  crossing  at  right  angles  the  direction  of  its  fibres,  and  connects  the  anterior  and  superior  with  the  pos- 
terior and  inferior  convolutions. 

Rolando  has  not  been  so  successful  in  his  researches  into  the  structure  of  the  cerebrum  as  in  his  investiga- 
tions into  that  of  the  cerebellum:  the  following  are  the  results  which  he  obtained  by  tearing  the  brain,  and 
by  examining  this  organ  in  the  foetus.  According  to  him,  the  brain  is  composed  of  fibres  arranged  in  layers  in 
tiie  following  order,  proceeding  from  without  inward:  1.  A  white  layer  reaching  into  the  fissure  of  Sylvius, 
and  covered  by  gray  matter  ;  2.  A  layer  from  which  the  fibres  of  the  external  convolutions  arise  ;  3.  A  layer 
which  is  formed  by  the  fibres  of  the  peduncles,  and  supplies  the  convolutions  of  the  inner  border  of  the  hemi- 
sphere ;  4.  A  plane  which  extends  from  the  optic  thalami  to  the  parietes  of  the  lateral  ventricles,  to  form  the 
corpus  callosum  ;  5.  A  system  of  longitudinal  fibres  which  form  the  convolutions  situated  upon  the  inner  sur- 
I'ace  of  the  hemispheres ;  6.  A  system  of  medullary  fibres  which  constitute  the  fornix  and  coniu  ammonis  ;  7, 
Intermil  and  external  corpora  striata,  to  which  must  be  added  the  antenor  commissures,  the  perforated  layer, 
and  the  fasciculus  of  the  external  corpus  geniculatum.  X  Vide  Tiedemann  (translated  by  M.  Jourdan) 


COMPARATIVE    ANATOMY   OF    THE    CEREBRUM.  ?ST 

corpus  callosum  begins  to  appear  under  the  form  of  a  narrow  commissure,  which  unites 
the  two  hemispheres  in  front,  they  being  completely  separated  behind. 

In  the  fourth  and  fifth  months,  the  cerebrum  covers  the  anterior  part  of  the  tubercula 
quadrigemina.  The  posterior  lobe  exists,  the  fissure  of  Sylvius,  which  is  well-marked, 
separating  it  from  the  anterior  lobe.  We  observe  here  and  there  some  small  depres- 
sions, the  traces  of  anfractuosities.  The  olfactory  nerves,  which  are  very  large,  and  are 
said  to  have  been  found  hollow,  as  in  the  lower  animals,  appear  to  arise  from  the  Sylvian 
fissure.  The  corpus  callosum  is  still  very  small,  so  that  the  optic  thalami  and  the  third 
ventricle  are  exposed.  At  this  period  the  human  brain  has  some  analogy  with  that  of 
the  rodentia. 

In  the  sixth  month,  the  cerebrum  covers  the  tubercula  quadrigemina  and  the  greater 
part  of  the  cerebellum.  The  only  traces  of  convolutions  are  found  upon  the  internal 
surface  of  the  hemispheres.  The  corpus  callosum  is  prolonged  backward  with  the  hem- 
ispheres, and  from  being  vertical,  now  becomes  horizontal. 

At  the  seventh  month,  the  corpora  albicantia,  which  had  hitherto  formed  a  single  mass, 
as  in  the  lower  animals,  become  separated.  The  convolutions  are  defined,  and  the  cere- 
brum projects  behind  the  cerebellum. 

The  changes  occurring  in  the  eighth  and  ninth  months  appear  to  be  the  development 
of  the  convolutions  and  the  perfection  of  the  other  parts  of  the  brain.  At  this  period 
the  characters  of  the  human  brain  are  well-defined.  It  may  not  be  impossible,  perhaps,  to 
recognise,  in  the  rapid  phases  of  this  development,  the  characters  of  the  brain  in  the 
different  orders  of  mammalia,  but  it  is  necessary  to  observe  greater  caution  in  admit- 
ting these  analogies  than  has  been  evinced  by  various  naturalists. 

As  the  corpus  callosum  continues  to  be  developed  backward,  it  ends  by  reaching  the 
anterior  tubercula  quadrigemina. 

The  corpora  striata  do  not  exhibit  their  white,  radiating  fibres  until  near  birth,  or  soon 
after  it.  The  originating  fasciculi  of  the  fornix  are  not  seen  in  the  interior  of  the  optic 
thalami  until  the  latter  months  of  intra-uterine  life ;  and  until  then,  also,  the  transverse 
commissures  and  the  white  fibres  of  the  optic  commissure  do  not  appear.* 

The  lateral  ventricles  are  formed  by  the  turning  backward  and  inward  of  the  membrane 
which  constitutes  the  hemispheres.  And  as  this  membrane  is  very  thin  until  the  end  of 
the  third  month,  it  follows  that  at  this  period  the  lateral  ventricles  are  proportionally  much 
larger  than  they  are  afterward.  The  anterior  cornua  of  these  ventricles  are  developed 
before  the  descending  cornua,  and  these  before  the  posterior  cornua.  During  all  this  pe- 
riod, the  anterior  cornua  communicate  with  the  cavities  in  the  olfactory  nerves.  At  the 
sixth  month,  the  lateral  ventricles  are  completely  closed.  The  choroid  plexuses,  which 
exist  in  all  animals  provided  with  lateral  ventricles,  begin  to  appear  as  soon  as  these 
cavities. 

The  distinction  between  the  gray  and  white  matter  does  not  become  evident  until  af- 
ter birth.  Tiedemann  is  of  opinion  that  the  formation  of  the  gray  matter  takes  place 
after  that  of  the  white.  This  appears  to  me  a  pure  hypothesis.  The  two  substances  are 
formed  at  the  same  time  ;  but,  properly  speaking,  they  are  neither  white  nor  gray,  and 
they  do  not  acquire  their  distinctive  characters  until  some  little  time  afterward. 

Comparative  Anatomy  of  the  Cerebrum. 

The  Optic  Thalami  and  Corpora  Striata. 

In  analyzing  the  brains  of  the  lower  animals,  it  is  of  the  utmost  importance  clearly  to 
distinguish  the  hemispheres,  properly  so  called,  from  the  optic  thalami  and  corpora  striata. 

The  optic  thalami  are  recognised  by  their  having  a  ventricle  (the  third)  between  them, 
by  being  connected  by  an  anterior  and  a  posterior  commissure,  and,  moreover,  by  being 
continuous  with  the  cerebral  peduncles. 

The  size  of  the  optic  thalami  is  always  proportioned  to  that  of  the  hemispheres.  In 
fishes,  the  cerebrum  appears  to  be  almost  entirely  formed  by  the  optic  thalami. 

There  are  no  traces  of  corpora  striata  in  fishes.  Their  existence  in  reptiles  cannot 
be  doubted.  They  are  of  enormous  size  in  birds,  in  which  they  constitute  almost  the 
entire  hemispheres.  If  it  be  true  that,  in  the  animal  series,  the  size  of  the  hemispheres 
is  always  directly  proportioned  to  that  of  the  optic  thalami,  such  is  not  the  case  with  the 
corpora  striata,  which,  as  I  have  already  stated,  are  a  kind  of  internal  convolutions,  and 
are  often  inversely  proportioned,  in  size,  to  the  hemispheres,  properly  so  called. 

Thus,  the  corpora  striata  are  very  large  in  proportion  to  the  hemispheres  in  the  ro- 
dentia :  in  this  respect,  as  in  many  others,  the  brain  of  this  order  of  mammalia  approach- 
es very  near  to  that  of  birds.  In  the  higher  orders  of  mammalia,  as  the  carniyora  and 
quadrumana,  the  proportion  between  the  corpora  striata  and  the  hemispheres  is  neariy 
the  same  as  in  the  human  subject. 

*  [Tiedemann  describes  fibres  as  distinctly  appearing-  in  the  corpus  striatum  in  the  sixth  month,  though 
not  so  abundantly  as  afterward.  He  recog:nised'the  anterior  and  posterior  commissures  before  the  end  of  the 
third  month  ;  at  the  same  time,  also,  the  anterior  pillars  of  the  fornix  rising-  from  the  united  mass  of  the  cor- 
pora albicantia  ;  the  fasciculi  from  the  thalami  to  the  corpora  albicantia  were  quite  distinct  in  the  fifth  month, 
and  could  be  recognised  even  somewhat  earlier.] 


758  NEUROLOGY. 

The  Cerebral  Hemispheres  and  Olfactory  Lobes. 

In  Mammalia.  —Man  surpasses  all  the  mammalia  in  regard  to  the  size  of  the  cerebral 
hemispheres  and  the  number  of  their  convolutions. 

The  quadrumana  stand  next  to  man.  The  dolphin,  perhaps,  exceeds  the  ape  in  both 
respects,  and  this  would  tend  to  support  the  relations  of  travellers  respecting  the  won- 
derful intelUgence  of  this  cetaceous  animal. 

In  the  carnivora  and  ruminantia  the  hemispheres  are  smaller,  the  occipital  lobe  of  the 
cerebrum  does  not  exist,  and  the  anterior  part  only  of  the  cerebellum  is  covered.  There 
is  no  fissure  of  Sylvius,  and  no  lobe  of  the  corpus  striatum.  In  all  these  animals,  the 
number  of  the  convolutions  and  the  depth  of  the  anfractuosities  have  appeared  to  me 
to  be  as  great  as  they  are  in  man,  in  proportion  to  the  size  of  the  hemispheres.  I  have 
not  observed  that  regularity  of  the  convolutions  which  several  anatomists  have  pointed 
out  as  contrasting  with  their  irregularity  in  man. 

The  lowest  order  of  mammalia,  namely,  the  rodentia,  have  the  letist  complicated  brain. 
It  is  shaped  like  the  heart  on  playing  cards,  almost  resembling  the  brain  of  birds.  The 
cerebellum  is  completely  exposed,  and  the  tubercula  quadrigemina  are  but  partially  cov- 
ered by  the  cerebrum.  There  are  scarcely  any  traces  of  convolutions,  and  the  hemi- 
spheres are  reduced  to  a  membrane  folded  upon  itself 

The  corpus  callosum  is  extremely  small,  but  the  cornu  ammonis  is  very  large.  These 
two  parts  seem  to  be  developed  inversely  to  each  other.  Thus,  the  corpus  callosum  is 
larger  and  the  cornu  ammonis  is  smaller  in  man  than  in  the  lower  animals. 

In  the  rodentia,  the  gray  matter  of  the  convolutions  is  reflected  beneath  the  fornix.* 

In  all  mammalia,  excepting  the  dolphin,  the  olfactory  nerves,  which  are  so  delicate  in 
man,  form  two  thick  pedicles  lying  under  the  anterior  lobes  of  the  cerebrum,  and  termi- 
nating in  front  by  large  ovoid  bulbs,  corresponding  in  size  to  that  of  the  ethmoidal  fossae ; 
these  enlargements  are  named  olfactory  lobes.  They  are  continuous  with  the  innermost 
convolutions  of  the  sphenoidal  horn  of  the  posterior  lobe,  which  presents,  above  and  be- 
low, certain  white  fibres  or  striae,  that  are  continuous  with  the  cerebral  peduncles. 

The  olfactory  lobes  have  no  relation  with  the  corpora  striata,  as  Cuvier  was  the  first 
to  observe.     In  the  dolphin,  as  in  man,  the  corpora  striata  are  very  much  developed. 

The  development  of  the  olfactory  lobe  is  inversely  proportioned  to  that  of  the  cornu 
ammonis. 

In  Birds. — The  cerebral  hemispheres  in  birds  are  shaped  like  a  heart  on  playing  cards, 
as  in  the  rodentia  ;  there  are  no  lobes  and  no  convolutions,  excepting  a  very  superficial 
longitudinal  furrow,  situated  on  each  side  of  the  median  line.  The  brain  almost  entire- 
ly consists  of  the  corpora  striata.  The  hemisphere  is  formed  by  a  very  thin  gray  lamina, 
upon  which  are  observed  certain  white  radiated  fibres.  This  lamina  commences  at  the 
inner  part  of  the  corpus  striatum,  turns  outward  round  that  body,  and  is  continued  to  the 
upper  part.  The  interval  between  this  lamina  and  the  corpus  striatum  forms  the  lateral 
ventricle.  There  is  no  trace  of  the  corpus  callosum,  but  there  is  evidently  an  anterior 
commissure,  which  expands  in  the  corpora  striata. 

In  all  birds  of  prey,  two  medullary  bands  arise  in  front  of  the  commissure  of  the  optic 
nerves,  and,  having  reached  the  front  of  the  hemispheres,  are  expanded  to  form  the  ol- 
factory lobes.  In  the  other  tribes,  as  in  the  gallinaceae,  there  are  no  olfactory  lobes,  but 
certain  small  cords,  which  are  merely  the  tapered  extremities  of  the  hemispheres. 

In  Reptiles. — The  hemispheres  are  larger  in  the  chelonians  (tortoise)  than  in  birds, 
though  they  are  very  similar  in  many  respects  :  as  in  birds,  there  are  no  olfactory  lobes, 
but  merely  two  bands.  In  the  saurians  (crocodile,  lizard)  the  olfactory  lobe  is  continued 
into  the  tapering  point  of  the  cerebral  lobe  by  a  very  long  pedicle.  The  batrachians  and 
ophidians  have  olfactory  lobes  in  front  of  the  hemispheres,  from  which  they  are  separa- 
ted by  a  circular  constriction. 

In  Fishes. — Like  reptiles,  fishes  have  sometimes  a  single  pair,  sometimes  two  pairs 
of  lobes  in  front  of  the  optic  lobes.  When  there  is  only  one  pair,  it  must  not  be  conclu- 
ded that  they  represent  the  cerebral  hemispheres  ;  if  that  pair  is  continuous  with  the  ol- 
factory nerves,  they  constitute  the  olfactory  lobes.  Whenever  there  is  a  pair  of  lobes 
between  the  olfactory  and  the  optic  lobes,  such  pair  belongs  to  the  hemispheres. 

The  olfactory  lobes  and  the  cerebral  hemispheres  are  so  independent  of  each  other, 
tliat  they  are  often  inversely  proportioned  in  regard  to  size,  so  that  the  cerebral  hemi 
spheres  are  larger  in  man  than  in  any  of  the  lower  animals,  while  the  olfactory  lobes  are 
smaller.  On  the  other  hand,  the  olfactory  lobes  are  the  most  highly  developed  in  the 
ray ;  they  are  united  together,  are  hollowed  in  the  centre,  grooved  on  the  surface,  ac- 
cording to  the  observation  of  Vicq  d'Azyr,  and  present  some  traces  of  convolutions. 
Now,  in  the  ray,  there  are  no  cerebral  hemispheres,  at  least,  unless  we  agree  with  Tiede- 
mann  in  regarding  the  olfactory  lobes  as  anologous  to  the  corpora  striata.  In  some  fish- 
es the  olfactory  lobe  is  supported  by  a  pedicle  of  variable  length.  As  to  the  cerebral 
hemisphere,  it  is  a  mere  tubercle,  which  appears  to  represent  the  optic  thalamus. 

*  [Mr.  Owen  has  discovered  that  the  brain  of  marsupial  animals  resembles  that  of  birds,  in  wanting  the  cor- 
pus callosum  (see  his  Memoir  in  Phil.  Trans.,  1837).] 


THE   NERVES.  7S6 

The  corpus  callosum,  the  fornix,  and  the  septum  lucidum  do  not  exist  either  in  birds, 
reptiles,  or  fishes. 

The  corpora  albicantia,  which  are  wanting  in  birds  and  reptiles,  are  of  enormous  size 
in  fishes,  and  constitute  a  true  lobe,  according  to  Vicq  d'Azyr  and  Arsaky. 

The  encephalon  of  fishes  presents  five  pairs  of  lobes,  which  are,  proceeding  from  be- 
hind forward,  1.  The  lobes  of  the  pneumogastric  nerve,  or  lobe  of  the  medulla  oblongata ; 
2.  The  cerebellum  ;  3.  The  optic  lobes  ;  4.  The  cerebral  hemispheres  ;  5.  The  olfactory 
lobes. 

If  we  now  generalize,  with  M.  de  Blainville,  the  notions'we  have  formed  respecting 
the  encephalon  of  vertebrate  animals,  we  may  regard  the  different  pairs  of  lobes  of  the 
encephalon  as  so  many  pairs  of  ganglia  situated  upon  the  prolongation  of  the  spinal  cord ; 
these  he  names  ganglions  saris  appareil  exterieur.  The  first  or  the  most  anterior  pair 
consists  of  the  olfactory  lobes,  which  are  rudimentary  in  man.  The  second  is  the  cere- 
brum, properly  so  called.  The  third  is  formed  by  the  tubercula  quadrigemina  or  optic 
lobes,  which  are  rudimentary  in  man.  The  fourth  is  the  cerebellum.  The  gangha 
which  constiJ;ute  each  pair  communicate  with  each  other ;  each  gangUon  communicates 
with  that  which  precedes  and  that  which  follows  it  •  and,  lastly,  they  all  communicate 
with  the  spinal  cord.* 


THE  NERVES,  OR  THE  PERIPHERAL  PORTION  OF  THE  NERVOUS 

SYSTEM. 

General  Remarks. — History  and  Classification. — Origin,  or  Central  Extremity. — DiffererU 
Kinds. — Course,  Plexuses,  and  Anastomoses. — Direction,  Relations,  and  Mode  of  Divis- 
ion.— Termination. — Nervous  Ganglia,  and  the  Great  Sympathetic  System. — Conneximu 
of  the  Ganglia  with  each  other,  and  with  the  Spinal  Nerves. — Structure  of  Nerves. — Struc 
ture  of  Ganglia. — Preparation  of  Nerves. 

General  Remarks. 

The  nerves,  which  are  concerned  in  the  transmission  of  sensations  and  of  motor  influ- 
ence, are  white  cords,  attached  to  the  cerebro-spinal  axis  by  one  extremity  (the  central 
extremity),  and  distributed  to  the  different  organs  by  the  other,  or  peripheral  extremity. 
They  have  a  pearly-white  aspect,  like  the  tendons,  with  which  they  were  for  some  time 
confounded.  Their  surface  is  smooth,  and  presents  a  number  of  folds  or  zigzag  marks, 
which  are  effaced  by  extension.!  Lastly,  if  a  nerve  be  cut  across,  it  is  seen  to  be  com- 
posed of  a  certain  number  of  cords,  the  divided  ends  of  which  project  beyond  the  cut 
surface.  By  these  characters  it  will  always  be  easy  to  distinguish  a  nerve  from  any 
other  white  tissue  in  the  body. 

All  the  nerves  are  arranged  in  pairs :  they  differ  from  each  other  in  their  point  of 
junction  with  the  central  portion  of  the  nervoiis  system  ;  in  their  consistence  ;  in  the 
place  at  which  they  emerge  from  the  cranio-vertebral  cavity ;  in  their  distribution  ;  and 
in  their  functions.  These  points  of  difference  have  served  as  the  foundations  of  the  dif- 
ferent classifications  of  the  nerves  proposed  at  various  periods. 

History  and  Classification  of  the  JSTerves. 
The  nerves,  which  had  been  at  first  confounded  with  the  tendons  and  ligaments  under 
the  name  of  white  tissues,  were  distinguished  from  those  parts  by  Herophilus  and  Galen. 
The  subdivision  of  the  nerves  into  the  cerebral  or  cranial  nerves,  which  pass  out  of  the 
foramina  in  the  base  of  the  scull,  and  the  spinal  or  rachidian  nerves,  which  emerge  from 
the  inter- vertebral  foramina,  was  so  natural,  that  it  suggested  itself  to  the  earliest  anat- 
omists who  directed  their  attention  to  this  system.  The  cranial  nerves  alone  have  pre- 
sented some  difficulties  in  their  study  and  their  classification.  Marinus,  whose  work 
has  been  long  regarded  £is  classical,  admitted  only  seven  pairs  of  cranial  nerves,  among 
which  neither  the  olfactory  nor  the  pathetic  were  included.  Achillini  was  the  first  who 
described  the  latter  as  a  special  nerve  ;  and  it  was  Massa  who  classed  the  olfactory  rib- 
and among  the  nerves.  Willis  divided  the  cranial  nerves  (and  his  division  is  still  adopt- 
ed) into  ten  pairs,  including  the  sub-occipital  nerve.  He  also,  like  his  predecessors,  ad- 
mitted thirty  pairs  of  spinal  nerves,  and  regarded  the  great  sympathetic  as  forming  the 
forty-first  pair.  According  to  Willis,  the  olfactory  nerves  form  the  first  cranial  pair ; 
the  optic  nerves,  the  second  ;  the  common  motor  nerves  of  the  eyes,  the  third  ;  the  pa- 
thetic nerves,  the  fourth ;  the  trigeminal  nerves,  the  fifth  ;  the  external  motor  nerves, 
the  sixth  ;  the  facial  and  auditory  nerves  together,  the  seventh ;  the  pneumogastric, 
glosso-pharyngeal,  and  spinal  accessory,  the  eighth  ;  the  hypoglossal  nerves,  the  ninth  ; 
and  the  sub-occipital  nerves,  the  tenth.    This  last  pair,  which  was  with  so  much  reason 

*  [There  is  still  considerable  uncertainty  as  to  the  parts  of  the  encephalon  which  correspond  iu  the  higher 
and  lower  vertebrata.  For  farther  information  on  this  point,  as  well  as  on  the  comparative  anatomy  of  the 
brain  generally,  see  Leuret,  Anatomic  Comparee  du  Systime  Nervevus,  Paris,  1839.] 

\  [These  zig^zag  folds  led  some  anatomists  to  believe  that  the  nerves  have  a  sinuous  arrangement.  Monro 
has  even  commemorated  this  anatomical  error  by  a  figure.  The  sinuous  appearance  common  to  the  nerve* 
and  tendons  disappears  in  both  by  stretching.] 


760  NEUROLOGY. 

classed  by  Haller  among  the  spinal  nerves,  has  been  alternately  and  arbitrarily  removed 
from  one  to  the  other  class  of  nerves.  Soemmering  divided  the  seventh  pair  of  Wilhs 
into  two  distinct  pairs  :  the  seventh,  or  the  facial  nerves  ;  and  the  eighth,  or  the  audi- 
tory nerves  :  he  subdivided  the  eighth  pair  of  Willis  into  three  pairs,  namely,  the  ninth, 
or  the  glosso-pharyngeal ;  the  tenth,  or  the  pneumogastric ;  and  the  eleventh,  or  the 
spinal  accessory  nerves  of  Willis.  But  Soemmering's  modification,  as  well  as  Mala- 
carne's,  who  admitted  fifteen  pairs  of  cranial  nerves,  and  also  Paletta's,  who  described 
as  a  particular  nerve  that  branch  of  the  fifth  pair  which  is  distributed  to  the  temporal 
and  buccinator  muscles,  appear  to  me  to  be  faulty,  because  they  cause  a  confusion  of 
ideas  without  leading  to  any  advantage.  We  shall,  therefore,  adhere  to  the  classifica- 
tion of  Willis,  which  is  most  generally  adopted.  Nevertheless,  with  Vicq  d'Azyr,  we 
shall  prefer  a  nomenclature  founded  upon  the  distribution  of  the  nerves  to  one  which  is 
purely  numerical. 

Willis  conceived  the  grand  idea  of  separating  the  nerves  of  voluntary  from  those  of 
involuntary  motion.  Bichat  seized  upon  this  idea,  which  had  already  been  rendered 
fruitful  by  Winslow  and  Reil ;  he  unfolded  it  even  to  the  minutest  details,  and  appropri- 
ated to  himself,  in  some  measure,  the  distinction  of  the  nerves  into  those  of  organic  and 
those  of  animal  life.  The  cerebro-spinal  nerves  constitute  the  nervous  system  of  ani- 
mal life  ;  the  great  sympathetic  nerve  fonns  by  itself  the  nervous  system  of  organic  life. 
This  last-named  nerve  consists  of  a  series  of  gangha,  or  small  nervous  centres,  distinct 
from  each  other  and  from  the  brain.  Bichat,  moreover,  anticipating  all  the  importance 
of  the  origin  of  the  nerves,  endeavoured  to  class  them,  not  according  to  the  points  at 
which  they  emerged  from  the  cranium,  but  according  to  their  origin,  viz.,  into  the  nerves 
of  the  cerebrum,  which  are  ten  in  number ;  the  nerves  of  the  pons  Varolii,  six  in  num- 
ber ;  and  the  nerves  of  the  spinal  marrow,  thirty-four  in  number ;  the  only  disadvantage 
of  this  classification  consists  in  its  having  been  premature. 

Other  less  important,  and,  in  general,  rather  physiological  than  anatomical  subdivis- 
ions of  the  nerves,  have  been  established.  Thus,  in  reference  to  their  consistence,  the 
nerves  have  been  divided  into  the  hard,  which  are  motor  nerves,  and  the  soft,  which 
are  sensory  ;  the  former  are  said  to  come  from  the  spinal  cord,  the  latter  from  the  brain. 
The  old  distinction  of  the  nerves  into  nerves  of  sc?isatimi  and  nerves  of  motion  has  been 
lately  revived ;  and  we  shall  have  occasion  to  recur  to  it,  as  well  as  to  Sir  Charles  Bell's 
classification  of  the  nerves  into  the  symmetrical  or  primitive,  and  the  superadded  or  respi- 
ratory system. 

The  nerves  might  also  be  classified  according  to  their  size,  but  this  mode  of  distinc- 
tion would  be  completely  useless.  Every  nerve  presents  for  our  consideration  a  central 
oxtremity,  a  course,  and  a  peripheral  extremity. 

The  Central  Extremity  of  the  Jferves. 

The  central  extremity  of  the  nerves  is  that  part  by  which  they  communicate  or  are 
connected  with  the  cerebro-spinal  axis.  It  is  generally  called  the  origin  of  the  nerves. 
The  use  of  such  metaphorical  expressions  as  origin,  production,  and  efflorescence,  has 
not  been  without  disadvantage  to  science ;  for  by  the  majority  of  anatomists  they  are 
employed  not  in  a  figurative,  but  in  a  literal  sense.* 

The  examination  of  the  central  extremity  of  the  nerves  is,  perhaps,  the  most  impor- 
tant part  of  their  study,  because  the  properties  of  the  nerves  depend  in  a  great  measure 
upon  their  point  of  connexion  with  the  central  part  of  the  nervous  system.  This  point 
is,  in  reference  to  each  nerve,  constant  and  invariable,  not  only  in  man,  but  throughout 
the  animal  kingdom,  so  that  its  exact  determination  enables  us  to  establish  what  are  the 
analogous  parts  of  the  encephalon  in  different  species.  * 

Each  nerve  has  an  apparent  and  a  real  central  extremity  or  origin.  The  apparent  ori- 
gin is  the  exact  point  at  which  the  nerve  is  given  off  from  the  surface  of  the  cerebro- 
spinal axis ;  but,  as  several  nerves  can  be  traced  into  the  substance  of  the  cerebro-spinal 
axis  to  a  variable  depth,  it  is  probable  that  all  of  them  have  a  much  deeper  real  origin. 
The  older  anatomists  proceeded  on  this  supposition,  when  they  described  all  the  nerves 
as  originating  from  the  cerebrum,  and  more  particularly  from  the  corpus  callosum,  or, 
rather,  from  the  optic  thalami  and  corpora  striata.  We  are  still  ignorant  of  any  central 
point,  or  sensorium  commune,  forming  the  point  of  termination  or  of  origin  to  all  the  nerves 
of  the  body, 

In  respect  of  their  origin,  we  might  regard  all  the  nerves  as  proceeding  from  the  spi- 
nal cord  :  the  nerves  of  the  face,  and  those  of  the  organs  of  respiration  and  deglutition, 
arise  from  the  medulla  oblongata  and  its  cranial  prolongations  ;  the  nerves  of  the  upper 
extremity  proceed  from  the  cervico-dorsal  enlargement  of  the  cord  ;  and  the  nerves  of 
the  lower  extremity  from  the  lumbar  enlargement :  the  nerves  of  the  trunk  arise  from 
the  spinal  cord,  between  its  three  enlargements.  The  optic  and  olfactory  nerves  alone 
appear  to  form  exceptions  to  this  rule. 

All  the  spinal  nerves  present  the  greatest  uniformity  in  reference  to  their  origin, 

*  Comparative  anatomy,  and  the  anatomy  of  the  fcetus,  prove  the  independent  formation  of  the  different 
parts  of  the  nervous  system. 


DIFFEREIVT   KINDS    OF    NERVES.  761 

course,  and  termination.  The  arrangement  of  the  cranial  nerves,  which  appears  at  first 
sight  to  be  uninfluenced  by  the  laws  which  regulate  the  distribution  of  the  spinal  nerves, 
may  yet  be  referred  to  those  laws  to  a  certain  extent,  notwithstanding  its  apparent  ir- 
regularity and  complexity. 

The  general  remarks  wiiich  follow  apply  more  particularly  to  the  spinal  nerves. 

The  spinal  nerves  arise  by  two  sets  of  roots,  the  anterior  (a,  fig.  267)  and  the  poste- 
rior  (b). 

Gall  advanced  the  notion  that  the  posterior  roots  of  the  spinal  nerves  preside  over  ex- 
tension, and  the  anterior  roots  over  flexion  of  the  trunk  and  limbs,  and  he  explained  the 
predominance  of  extension  over  flexion  by  the  greater  size  of  the  former  roots.*  Al- 
though the  fact  of  this  predominance  appears  to  me  indisputable,  Gall's  explanation  is 
nevertheless  rendered  void,  for  it  supposes  a  separation  of  the  fibres  of  the  anterior  and 
posterior  roots  in  reference  to  their  distribution,  and  no  such  a  separation  exists. 

Sir  Charles  Bell,  having  proved  by  experiments  that  the  facial  nerve  and  the  fifth 
cerebral  nerve  had  different  properties,  the  former  being  devoted  to  motion  and  the  lat- 
ter to  sensation,  was  led  to  examine  whether  there  did  not  exist  something  analogous 
in  the  other  parts  of  the  body  ;  and  the  double  roots  of  the  spinal  nerves  must  have  natural- 
ly suggested  themselves  to  his  mind.  Might  not  the  object  of  this  double  origin  be  to 
concentrate  a  double  property  in  each  pair  of  nerves  1  Experiments  were  instituted, 
and  they  confirmed  the  preconceived  ideas  of  this  ingenious  physiologist.  They  were 
soon  followed  by  the  perfectly  confirmatory  experiments  made  by  Magendie,  who,  by  also 
adducing  facts  in  pathological  anatomy,  threw  so  much  light  upon  this  subject,  that  most 
modern  physiologists  have  admitted  that  the  posterior  roots  belong  to  sensation,  and  the 
anterior  to  motion. 

Now,  notwithstanding  the  imposing  authorities  which  I  have  quoted,  I  must  say  that 
I  am  by  no  means  convinced  of  the  reality  of  this  distinction,  and  that,  in  repeating  both 
Bell's  and  Magendie's  experiments,  the  section  of  the  anterior  and  that  of  the  posterior 
roots  appeared  to  me  to  produce  precisely  the  same  effects. + 

I  have  also  endeavoured  to  determine  the  question  anatomically. 

Some  anatomists  have  thought  that,  after  emerging  from  the  ganglion,  the  filaments 
from  the  two  roots  become  so  intimately  mingled  that  the  smallest  nervous  cord  would 
contain  filaments  from  both  the  anterior  and  the  posterior  roots  ;  as  far  as  I  have  been 
able  to  ascertain,  the  filaments  are  interlaced,  but  never  enter  into  a  regular  combination. 
Again,  in  order  to  render  the  dissection  more  easy  and  conclusive,  having  macerated  a 
portion  of  a  body  in  water  containing  nitric  acid,  and  having  tlius  destroyed  the  neuri- 
lemma or  fibrous  covering  of  the  nerves,  I  endeavoured  to  trace  some  nervous  filaments, 
both  cutaneous  and  muscular,  to  their  origin  ;  but  I  never  could  succeed  in  this,  so  nu- 
merous are  the  combinations  into  which  tlie  filaments  enter.  However,  having  directed 
my  attention  more  particularly  to  certain  filaments  given  off  from  the  cervical  nerves  to 
be  distributed  to  the  scaleni  muscles,  I  succeeded  in  tracing  them  into  the  correspond- 
ing spinal  gangli.  Now  the  filaments  which  proceed  directly  from  the  spinal  ganglia  are, 
according  to  the  theory  just  alluded  to,  exclusively  connected  with  sensation,  and,  con- 
sequently, should  not  be  distributed  to  the  muscles. 

The  question  of  the  anterior  and  posterior  roots  is  connected  with  another  more  gen- 
eral question,  viz..  Are  there  different  kinds  of  nerves  1 

Different  Kinds  of  JVerves. 

The  natural  distinction  of  the  nerves  into  those  of  sensation  and  of  motion  dates  as 
far  back  as  Erasistratus,  who  described  the  sensory  nerves  as  arising  from  the  meninges, 
and  the  motor  from  the  cerebrum  and  cerebellum.  This  opinion  was  often  revived  and 
always  abandoned,  and  it  was  only  when  direct  experiment  appeared  to  confirm  the  an- 
ticipations of  theory  that  it  became  generally  adopted. 

Bichat,  after  the  example  of  Winslow  and  Reil,  divided  the  nervous  system  into  two 
grcErt  sections,  one  of  which  belongs  to  animal  and  the  other  to  organic  life.  The  spinal 
cord  and  encephalon  form  the  common  centre  of  the  nervous  system  of  animal  life  ;  the 
organs  of  the  senses  and  the  muscles  are  under  its  influence.  All  the  organs  supplied 
by  it  are  subject  to  volition  and  consciousness.  The  nervous  system  of  organic  life  is 
formed  by  the  ganglia  of  the  great  sympathetic,  which  Bichat  agrees  with  Winslow  in 
regarding  as  so  many  little  brains.  The  organs  of  digestion,  respiration,  circulation, 
and  secretion  are  under  its  influence.  All  of  the  organs  which  it  supplies  are  withdrawal 
from  the  control  of  the  will  and  of  consciousness. 

The  subdivision  adopted  by  Reil  and  Bichat  prevailed  in  the  science  until  Sir  Charles 
Bell  was  led  back  to  the  opinion  of  the  ancients  by  some  highly  interesting*observations 
and  experiments  ;  he  associated  with  that  opinion  the  ideas  of  Bichat,  and  also  estab- 

*  In  this  matter  Gall  has  caufjht  sight  of  a  truth  which  I  believe  I  have  established  upon  incontestable  evi 
dencc,  in  describing  the  apparatus  of  locomotion  ;  namely,  that  in  all  parts  of  the  body,  excepting  in  the  mus- 
cles of  the  fingers,  the  extensors  are  more  powerful  than  the  flexors. 

t  [The  accuracy  of  the  experiments  has  now  been  amply  confirmed ;  and  there  is  no  doubt  that  the  ante- 
rior are  the  motor,  and  the  posterior  the  sensory  roots  :  no  difference  of  structure  has  been  detected  between 
tbem.J 

5  1) 


762  NEUROLOGY. 

lished  an  entirely  new  class  of  nerves,  wliicli  he  named  nerves  of  expression  or  respiratory 
nerves.  According  to  this  view,  there  are  five  kinds  of  nerves  :  nerves  intended  for  special 
sensations,  as  the  nerves  of  smell,  of  vision,  and  of  hearing  ;  nerves  of  common  sensation; 
nerves  of  volwntari/  motion ;  nerves  of  the  respiratory  movements  ;  and  sympathetic  nerves, 
which  appear  to  unite  the  body  into  a  whole  in  relation  to  its  nutrition,  its  growth,  and 
its  decay.  By  a  still  wider  generalization.  Sir  Charles  Bell  admits  two  systems  of 
nerves,  viz.,  the  the  primitive  or  symmetrical  nerves,  which  exist  in  all  animals,  and  by 
the  aid  of  which  they  feel  and  move  ;  and,  secondly,  the  superadded,  irregular,  or  respi- 
ratory nerves,  the  number  of  which  is  proportioned  to  the  perfection  of  the  general  organ- 
ization. It  is  the  latter  system  of  nerves  that  regulates  the  partly  voluntary  and  partly 
involuntary  act  of  respiration,  and  also  the  several  movements  connected  with  it,  such 
as  those  of  speaking,  laughing,  sighing,  and  sneezing.  According  to  Bell,  these  nerves 
arise  from  a  special  tract  in  the  cord,  and  sometimes  proceed  separately  or  distinct  from 
he  other  nerves,  and  are  sometimes  blended  with  them,  this  occurring  in  such  a  man- 
ner that  neither  their  union  nor  their  separation  in  any  way  impedes  their  functions. 

This  theory  of  superadded  or  respiratory  nerves  is  very  ingenious,  but  altogether  hy- 
pothetical. Besides,  it  is  only  strictly  applicable  to  the  case  of  four  nerves,  viz.,  the 
pneumogastric,  the  glosso-pharyngeal,  the  spinal-accessory,  and  the  facial.  Sir  C.  Bell'a 
opinion  concerning  the  existence  of  a  column  situated  between  the  anterior  and  poste- 
rior roots  of  the  nerves,  along  the  whole  extent  of  the  spinal  cord,  and  giving  origin  to 
certain  filaments  which  combine  with  those  coming  from  the  two  roots  so  as  to  cause 
them  to  participate  in  the  great  phenomenon  of  respiration,  is  quite  gratuitous. 

On  endeavouring  to  decide  whether  there  are  several  kinds  of  nerves,  by  anatomical 
investigation,  it  is  found  that,  excepting  the  olfactory,  optic,  and  acoustic  nerves,  which 
have  altogether  a  peculiar  arrangement,  and  the  ganglionic  nerves,  which  are  generally 
grayer  and  more  slender,  there  is  no  difference  in  the  character  and  structure  of  the 
nerves  of  different  parts  of  the  body.  The  cutaneous  nervous  filaments  are  exactly  sim- 
ilar to  the  muscular  nervous  filaments. 

From  the  law  of  organization,  that  identity  of  structure  is  always  connected  with  iden- 
tity of  function,  I  have  been  led  to  admit  that  the  nerves  are  homogeneous ;  that  the  dif- 
ferent properties  attributed  to  them  belong  to  the  organs  to  which  they  are  distributed ; 
and  that  they  perform  no  other  office  in  the  economy  than  that  of  conductors — conductors  of 
sensation  when  they  are  distributed  to  a  sensory  organ,  and  conductors  of  motor  influence 
when  they  enter  a  motor  organ.*  This  view  of  the  homogeneous  structure  of  the  nerves 
explains  much  more  readily  than  the  opposite  one  all  the  phenomena  of  innervation, 
and,  in  particular,  the  unity  of  all  parts  of  the  nervous  system. 

Moreover,  if  we  admit  the  existence  of  special  nerves  to  preside  over  some  special 
phenomena,  and  to  be  distributed  to  particular  organs,  why  not  admit  them  for  all  special 
actions  and  for  all  organs  1  There  would  then  have  to  be  digestive  nerves,  generative 
nerves,  and  secreting  nerves  of  different  kinds. 

Course^  Plexuses,  and  Anastomoses  of  the  JVerves. 

The  course  of  the  nerves  must  be  examined  both  while  they  are  within  and  while  they 
are  outside  the  cranio-vertebral  cavity.  Within  this  cavity  the  extent  of  their  course 
is  variable  ;  and  their  distribution,  after  they  have  emerged  from  it,  is  more  or  less  com- 
plicated. All,  or  nearly  all,  the  cerebro-spinal  nerves  communicate  with  the  great  sym- 
pathetic system.  When  the  parts  to  which  they  are  destined  are  not  complicated,  their 
distribution  is  very  simple,  as,  for  example,  the  nerves  of  the  thoracic  and  abdominal 
parietes  ;  but  when  those  parts  are  complicated,  the  arrangement  of  the  nerves  is  pro- 
portionally intricate ;  and  they  then  unite  so  as  to  form  certain  interlacements  called 
plexuses,  as,  for  example,  the  thoracic  and  abdominal  plexuses. 

The  nervous  plexuses,  which  Bichat  regarded  as  so  many  centres  in  which  the  branch- 
es of  origin  of  the  nerves  ended,  and  from  which  their  terminal  branches  commen 
ced,  are  Ibrmed  by  the  division  and  subdivision  of  a  certain  number  of  nerves,  wnich 
enter  into  new  combinations,  and  form  an  almost  inextricable  interlacement. 

Within  these  plexuses  there  is  generally  so  intimate  a  combination  of  the  different 
elements  of  which  they  are  composed,  that  it  is  almost  impossible  to  determine  exactly 
what  branches  of  origin  are  concerned  in  the  formation  of  any  particular  terminal  branch. 
A  branch  of  a  nerve  issuing  from  a  plexus  belongs,  therefore,  to  all  the  nerves  which  en- 
ter into  the  composition  of  that  plexus. 

The  plexuses  do  not  consist  of  actual  anastomoses  of  the  nervous  cords ;  nor  do  they, 
as  Monro  believed,  contain  any  gray  matter  :  they  do  not  afford  origin  to  any  new  ner- 
vous frlamenfs,  but  they  merely  give  off  those  which  they  have  received.  The  most 
careful  examination  reveals  nothing  more  than  an  interchange  of  nervous  cords,  which, 
although  they  enter  into  new  combinations,  still  remain  independent  of  each  other. 

*  The  homogeneous  structure  of  the  different  nerves  is  proved  by  the  anatomical  fact,  that  the  same  nerv« 
is  distributed  to  a  great  number  of  organs  having  very  diiferent  functions,  as,  for  example,  the  eighth  pair; 
and  also  by  a  fact  in  comparative  anatomy,  namely,  that  the  same  pair  of  nerves  may,  in.  different  species,  pre- 
side over  totally  different  functions  ;  for  example,  the  fifth  pair. 


DIRECTION    OF    THE   NERVES.  763 

The  term  nervous  anastomoses  is  applied  to  the  communications  by  loops,  or  at  more 
or  less  acute  angles,  which  take  place  between  the  nervous  filaments.  The  older  anat- 
omists, governed  by  the  idea  that  there  existed  a  fluid  circulating  in  the  nerves,  sup- 
posed that  in  the  anastomoses  of  nerves  there  was  a  mixture  of  nervous  fluids,  nearly 
similar  to  that  which  takes  place  in  vascular  anastomoses,  where  two  different  columns 
of  blood  are  intermixed.  They  regarded  the  nervous  anastomoses  as  the  most  active 
source  of  sympathies.  Bichat  also  admits  the  existence  of  these  anastomoses,  in  which, 
he  says,  there  is  not  only  a  contiguity,  but  also  a  continuity  of  nervous  filaments.  Be- 
clard*  defends  the  use  of  the  term  anastomosis,  and  endeavours  to  define  its  meaning 
thus  :  "  There  is  not  merely  an  application  of  nervous  filaments  in  the  anastomoses,  but 
a  true  communication,  a  junction  {abouchement)  of  their  canals,  which,  in  truth,  contain  a 
fixed  substance,  not  a  circulating  fluid,  as  was  formerly  believed." 

But,  on  examining  the  structure  of  the  nervous  anastomoses,  it  is  seen  that  there  is 
simply  a  juxtaposition  of  filaments  derived  from  two  different  sources.  The  examina- 
tion also  proves  most  distinctly  that  the  anastomoses  are  merely  small  plexuses,  so  that 
the  only  difference  between  them  is,  that  in  the  -plexuses  there  is  an  interchange  of  nervous 
cords,  while  in  the  anastomoses  there  is  an  interchange  of  nervous  filaments  or  of  primitive 
fibres.  The  anastomoses,  like  the  plexuses,  are  intended  to  concentrate  the  action  of 
several  nerves  upon  any  given  point,  as  on  a  centre,  from  which  their  action  may  ex- 
tend to  certain  parts  necessarily  connected  in  function. 

The  nervous  loops  described  by  Bichat  upon  all  points  of  the  median  line  of  the  body, 
and  by  the  existence  of  which  he  supposed  that  he  could  explain  the  return  of  sensation 
and  voluntary  motion  to  paralytic  parts  of  the  body,  do  not  exist.  The  only  anastomoses 
in  the  middle  line  with  which  I  am  acquainted  are  those  of  the  two  pneumogastric  nerves 
behind  the  lower  extremity  of  the  trachea,  that  of  the  two  solar  plexuses,  and  that  of 
the  cardiac  nerves. 

The  Direction,  Relations,  and  Mode  of  Division  of  the  Jferves. 

The  nerves  are  very  deeply  situated  at  their  egress  from  the  cranio-vertebral  cavity. 
Thus,  the  brachial  plexus  is  protected  by  the  osseous  girdle  of  the  shoulders,  and  the 
sacral  plexus  by  the  pelvic  bones.  The  nerves  then  pass  into  the  great  cellular  inter- 
vals, which  we  have  already  described  as  existing  in  the  limbs  for  the  reception  of  the 
principal  vessels  and  nerves,  and  for  the  preservation  of  those  parts  from  pressure. 

The  direction  of  the  nerves  is  generally  straight,  and  their  length  corresponds  exact- 
ly with  the  distance  from  their  point  of  origin  to  that  of  their  termination,  so  that,  if  the 
movements  of  the  hmbs  exceed  their  ordinary  extent,  the  nerves  may  suffer  severe  in- 
jury by  being  stretched.  This  straight  direction  is,  in  general,  an  essential  character  of 
a  nerve.  Nevertheless,  a  considerable  number  of  nerves  deviate  from  their  primitive 
direction,!  so  as  to  describe  a  portion  of  a  circle,  or  are  seen  reflected  upon  themselves 
in  a  direction  precisely  opposite  to  their  original  one.  Others  describe  a  zigzag  course, 
like  the  arteries  ;  but  these  flexuosities  are  effaced  in  certain  positions  of  the  body,  or 
during  the  distension  of  particular  organs. 

Although  there  is  but  one  arterial  trunk  for  each  limb,  there  are  always  several  nerves, 
the  number  of  these  being  variable.  As  the  arteries  often  deviate  from  their  original 
direction,  they  describe  certain  turns,  so  as  to  occupy  alternately  the  opposite  sides  of 
a  limb.  Now,  as  the  nerves  pass  in  a  straight  direction,  and  the  arteries  describe  cer- 
tain curves,  it  follows  that  the  same  nerves  cannot  accompany  the  same  arteries  during 
the  whole  of  their  course.  Thus,  when  an  artery  deviates  from  its  primitive  direction, 
it  has  two  satellite  nerves,  one  during  the  first,  and  the  other  during  the  second  part  of 
its  course.  For  instance,  the  crural  nerve  accompanies  the  femoral  artery,  and  the 
sciatic  nerve  the  popliteal  artery.  When  an  artery  bifurcates  or  otherwise  divides,  there 
is  often  a  particular  nerve  for  each  subdivision :  thus,  the  median  nerve  is  the  satellite 
of  the  brachial  artery,  the  radial  nerve  accompanies  the  radial  artery,  and  the  ulnar  nerve 
the  xdnar  artery. 

It  follows,  also,  from  what  has  been  said,  that  the  nerves  have  no  accompanying  ves- 
sel for  a  more  or  less  considerable  portion  of  their  course  ;  such  is  the  case  with  the 
great  sciatic  and  the  pneumogastric  nerves. 

The  relations  of  the  arteries  with  the  nerves  are  constant,  so  that  modem  surgeons 
attach  great  importance  to  these  relations  ;  in  fact,  as  a  nerve,  on  account  of  its  white- 
ness, is  more  easily  recognised  than  an  artery,  as  soon  as  the  former  is  exposed  the 
latter  is  immediately  met  with.  It  is  important,  moreover,  to  determine  with  the  great- 
est accuracy  what  nerves  are  contained  witliin,  and  what  nerves  are  situated  without, 
the  sheath  of  their  corresponding  artery.  Besides  its  principal  nervous  trunk,  an  artery 
is  also  accompanied  by  certain  nervous  filaments,  which  are  closely  applied  to  the  ves- 
sels, which  are  very  difficult  to  separate  from  it,  and  which  often  escape  observation 

*  Anat.  G6n6rale,  p.  659. 

t  I  do  not  think  that  a  straight  direction  is  necessary  for  the  transmission  of  the  nervous  influence,  for  this 
takes  place  in  a  lle.ve(J  limb  along  a  curved  nerve,  as  well  as  in  an  extended  limb  along  astraig'ht  nerve  ,  but 
it  is  probable  ihat  it  sliorteus  the  duration  of  this  trausmission. 


764  NEUROLOGY. 

from  their  tenuity.     These  are  the  filaments  which  render  ligature  of  the  arteries  so 
painful. 

Division  of  the  Nerves. — During  their  course,  the  nerves  do  not  divide,  like  the  vessels, 
by  ramifying  into  smaller  and  smaller  branches ;  but  they  give  off  in  succession,  as  they 
proceed,  branches  to  the  different  parts  through  vehich  they  are  passing,  and  thus  be- 
come gradually  exhausted,  until,  reduced  to  mere  filaments  themselves,  they  terminate 
in  the  same  manner  as  their  branches.  The  subdivision  of  nerves,  therefore,  docs  not  con- 
sist in  a  ramification,  but  in  a  process  of  separation  or  emission.  There  is  one  circumstance 
which  has  attracted  the  attention  of  all  anatomists,  viz.,  that  the  nerves  do  not  diminish 
in  size  in  proportion  to  the  number  of  filaments  given  off  from  them :  some  of  them 
even  appear  to  increase  in  size  after  having  given  off  several  filaments.  This  apparent 
singularity  is  explained,  not  by  the  fact  that  new  filaments  are  added,  but  by  the  flatten- 
ing of  the  nerve,  the  separation  of  its  filaments,  the  addition  of  a  certain  quantity  of  adi- 
pose tissue,  or  the  thickening  of  the  neurilemma. 

Termination  of  JVerves. 

The  distribution  of  the  nerves  is  perfectly  determinate  :  each  nerve,  indeed,  has  its 
own  distinctly  limited  department ;  an  arrangement  which,  connected  with  what  has  al- 
ready been  said  regarding  the  anastomoses,  explains  why  the  nerves  cannot  supply  the 
place  of  each  other.  When  the  principal  arterial  trunk  of  a  limb  is  tied,  the  circulation 
is  re-established  by  the  collateral  vessels  ;  but  when  a  nerve  is  cut  across,  all  the  parts 
to  which  it  is  distributed  are  paralyzed. 

The  termination  of  the  nerves  is,  undoubtedly,  one  of  the  most  important  points  in 
their  anatomy.  In  the  skin,  the  nerves  terminate  in  the  papillae,  not  one  of  which  is 
destitute  of  them  ;  in  the  muscles,  they  terminate  in  extremely  delicate  filaments,  which 
pursue  a  very  long  course  in  the  substance  of  these  organs,  before  they  become  invisible 
to  the  naked  eye  or  to  the  eye  aided  by  a  lens  :  it  has  appeared  to  me  that  each  nervous 
filament  was  so  arranged  as  to  be  in  contact  with  a  very  great  number  of  muscular  fibres, 
situated  either  in  the  same  or  in  different  planes. 

It  is  probable  that  there  is  not  a  single  muscular  fibre  which  is  not  thus  lightly  touched 
by  a  nervous  filament ;  this  anatomical  fact  may  suggest,  instead  of  Reil's  ingenious 
hypothesis  of  an  atmosphere  of  activity  around  each  nervous  filament,  the  important 
conclusion  that  the  nerves  act  upon  the  muscular  fibre  by  the  effect  of  contact.* 

MM.  Prevost  and  Dumas  believe  that  the  nervous  filaments  terminate  by  loops  in  the 
substance  of  muscles  ;  and  upon  their  incomplete  observations  they  have  founded  a  theory 
of  muscular  contraction.  Nervous  loops  may  certainly  be  observed  in  the  substance  of 
the  recti  muscles,  which  they  selected  as  examples  ;  but  these  loops  are  not  the  termina- 
tion of  the  nerves,  for  a  number  of  filaments  are  seen  to  issue  from  them,  and  to  be  dis- 
tributed in  the  manner  just  pointed  out.t 

The  different  organs  vary  much  in  regard  to  the  number  of  nerves  which  they  receive ; 
the  organs  of  the  senses — the  eyes,  the  ears,  the  nasal  fossae,  the  tongue,  and  the  skin — 
stand  first  in  this  respect.  Next  to  these  rank  the  muscles,  which  receive  nerves  in 
proportion  to  the  number  of  their  fibres  and  to  their  activity.  The  organs  of  nutritive 
life  are  far  removed  from  the  preceding  in  regard  to  the  quantity  of  nerves  distributed 
to  them.  No  proper  nerves  have  yet  been  discovered  in  cellular  tissue,  serous  mem- 
branes, tendons,  aponeuroses,  and  articular  cartilages.  All  the  articulations  are  provided 
with  nerves,  called  articular,  which  may  be  traced  into  the  ligaments,  and  even  upon  the 
synovial  membranes. 

The  long  bones,  in  addition  to  their  central  or  medullary  nerve,  have  certain  periosteal 
nerves  which  are  lost  in  the  periosteum,  and  also  proper  nerves  of  the  spongy  tissue, 
which  enter  the  foramina  at  the  extremities  of  these  bones.  •'• 

The  Nervous  Ganglia  and  the  Great  Sympathetic  System. 

The  nervous  ganglia  are  certain  grayish  knots  or  swellings  situated  along  the  course 
of  the  nerves,  and  having  a  rather  close  resemblance  to  the  lymphatic  glands  or  ganglia. 
Considered  generally,  the  ganglia  are  a  kind  of  nervous  centres,  towards  which  a  certain 
number  of  filaments  converge,  and  from  which  they  again  pass  out  under  new  combina- 
tions.   Hence  arose  the  ingenious  idea  of  Winslow,  who  compared  the  ganglia  to  little 

*  This  hypothesis  of  a  nen-ous  atmosphere  was  suggested  to  Reil  by  the  theory  of  a  nervous  fluid,  which  he 
regarded  as  analogous  to  and  almost  identical  with  the  electric  fluid  ;  and  also  by  the  fact  that  the  nervous  ap- 
paratus is  not  able  to  supply  filaments  to  all  the  muscular  fibres. 

t  [The  loops  described  l)y  Provost  and  Dumas  seem  to  have  consisted  of  small  nervous  cords  ;  but  Valentin, 
Emmert,  and  Burdach  have  observed  that  the  ultimate  filaments  (primitive  fibres  of  MiiUcr)  have  a  loop-like 
termination  iu  the  muscles.  In  reference  to  the  nerves  of  sensation,  it  has  been  observed  by  Valentin  and 
Burdach,  that  in  the  frog's  skin  the  primitive  fibres  end  in  loops  ;  this  mode  of  termination  has  also  been  seen 
by  Schwann  in  the  tail  of  the  larva  of  the  toad,  and  in  the  frog's  mesentery.  Schwann  farther  states,  that  in 
both  these  cases  the  nervous  fibres  gave  off  exceedingly  small  fibrils,  on  which  minute  swellings  (ganglia)  were 
placed,  and  which  in  some  situations  formed  a  network.  In  the  papilla:  of  the  human  skin,  Breschet  thought 
he  saw  the  nerves  ending  in  loops ;  and  Gherber  believes  that  he  has  seen  these  terminal  loops  in  the  skin  of 
quadrupeds.  Observers  differ  in  their  account  of  the  mode  of  termination  of  the  optic  and  auditory  nerves  <»«* 
Organs  of  Sight  and  Heaking).] 


CONNEXIONS    QF    THE    GANGLIA.  765 

brains  ;  an  idea  which  was  revived  under  a  modified  form  by  Bichat,  who  made  it  the 
basis  of  his  admirable  chapter  upon  the  nervous  system  of  organic  hfe. 

The  nervous  system  of  invertebrate  animals  is  reduced  to  a  series  of  ganglia  and  gan- 
glionic nerves ;  Swammerdam,  Haller,  and  the  older  anatomists  regarded  this  series  of 
ganglia  as  a  spinal  cord  enlarged  at  intervals.  But  there  is  no  point  of  comparison  be- 
tween these  two  parts ;  in  a  word,  the  enlargements  of  the  spinal  cord  and  brain  cannot 
be  likened  in  any  respect  to  the  ganglionic  enlargements. 

There  are  three  series,  or,  as  some  say,  three  kinds  of  ganglia :  viz.,  the  spiTial  or 
rachidian  ganglia ;  the  intercostal  ganglia ;  and  the  splanchnic  ganglia ;  these  last  are  situ- 
ated near  the  viscera  for  which  they  are  intended. 

The  first  series,  or  the  spinal  ganglia,  belong  to  the  organs  of  relation.  They  are  con- 
stant, regular,  and  symmetrical,  like  the  nerves  upon  which  they  are  placed.  The  other 
two  series  are  destined  for  the  apparatus  of  nutritive  life,  and  constitute  the  great  sym- 
pathetic system,  improperly  called  the  ganglionic  system. 

The  identity  in  nature  between  the  spinal  ganglia  and  the  ganglia  of  the  great  sympa- 
thetic, and  also  between  the  cerebro-spinal  and  the  ganglionic  system  of  nerves,  is  de- 
monstrated by  the  fact  that  in  a  great  number  of  animals  the  ganglia  are  blended,  or,  as 
it  were,  fused  together.  M.  Weber  {Anat.  Comparee  du  Nerf  Sympathique,  1817)  has  ob- 
served, that  in  animals  the  development  of  the  great  sympathetic  is  always  inversely  pro- 
portioned to  that  of  the  spinal  cord.  He  has  established  a  similar  relation  between  the 
great  sympathetic  and  the  pneumogastric  nerve ;  and,  indeed,  in  certain  species  the  latter 
nerve  entirely  replaces  the  former. 

The  experiments  of  M.  Legallois  upon  the  spinal  cord  led  him  to  admit  that  the  vis- 
ceral nerves  are  under  the  influence  of  the  spinal  cord,  and  that  the  roots  of  the  great 
sympathetic  are  in  the  cord. 

There  are  as  many  spinal  ganglia  on  each  side  as  there  are  spinal  nerves.  The  gan- 
glia of  the  great  sympathetic  in  the  sacral,  lumbar,  and  dorsal  regions,  are  as  numerous 
as  the  spinal  ganglia ;  in  the  cervical  region,  there  are  only  two  or  three  sympathetic 
ganglia  to  correspond  to  the  eight  spinal  ganglia.  The  superior  cervical  ganglion  may 
be  supposed  to  represent  several  ganglia. 

In  the  cranium  it  is  difficult  to  find  any  ganglia  corresponding  to  the  spinal ;  still,  the 
Gasserian  ganglion,  and  the  ganglion  of  the  eighth  pair,  may  be  regarded  as  analogous 
to  them. 

On  the  other  hand,  we  may  regard  the  ophthalmic  ganglion,  the  spheno-palatine  or 
Meckel's  ganglion,  the  otic  ganglion,  and  even  the  upper  part  of  the  superior  cervical 
ganglion,  as  forming  the  cranial  ganglia  of  the  sympathetic  system. 

Nevertheless,  it  would,  perhaps,  be  more  rational  to  regard  the  ophthalmic  and  otic 
ganglia  as  quite  independent  of  the  three  above-mentioned  series  of  ganglia,  and  as  con- 
nected with  certain  local  functions.  There  are  a  considerable  number  of  these  local 
ganglia,  which  have  received  no  particular  names,  and  which  I  shall  hereafter  point  out. 

Connexions  of  the  Ganglia  with  each  other,  and  with  the  Cerebro-spinal 

JSTerves. 

The  spinal  ganglia  belong  specially  to  the  posterior  roots  of  the  spinal  nerves ;  but  it 
will  presently  be  seen  that  the  anterior  roots  are  not  altogether  unconnected  with  them. 

From  the  spinal  ganglia  proceed  three  branches,  viz.,  a  middle  branch,  forming  the 
continuation  of  the  spineil  ners'e  ;  an  anterior  or  ganglionic  branch,  proceeding  to  the  cor- 
responding ganglion  of  the  great  sympathetic ;  and  a  posterior  branch,  which  is  distribu- 
ted to  the  muscles  and  skin  on  the  posterior  region  of  the  trunk. 

Each  of  the  ganglia  of  the  great  sympathetic  receive  one  or  several  filaments  from  the 
spinal  ganglia,  and  also  a  connecting  cord  from  the  sympathetic  ganglion  immediately 
above  it ;  and  each  of  them  gives  off  a  connecting  cord  to  the  ganglion  next  below  it, 
and  also  certain  visceral  branches,  which  sometimes  terminate  directly  in  the  viscera, 
and  sometunes,  when  their  distribution  is  complicated,  proceed  to  the  splanchnic  ganglia. 

Not  unfrequently  the  conmiunicating  cords  between  some  of  the  ganglia  of  the  sym- 
pathetic are  wanting,  and  the  continuity  of  this  nerve  is  then  interrupted.  Bichat  relies 
chiefly  upon  this  interruption  in  support  of  his  opinion,  that  the  great  sympathetic  is  not 
a  nerve  properly  so  called,  but  that  each  of  its  ganglia  is  the  centre  of  a  small  special  ner- 
vous system,  equally  distinct  from  the  cerebro-spinal  system  and  from  the  other  ganglia. 

The  splanchnic  ganglia  are  the  centres  or  points  of  convergence  of  a  great  number  of 
nerves,  of  which  some  are  derived  directly  from  the  cerebro-spinal  system,  and  others 
from  the  ganglia  of  the  great  sympathetic.  In  those  splanchnic  ganglia  which  approach 
the  median  line,  the  nerves  of  the  right  side  become  blended  with  those  of  the  left  by  a 
great  number  of  plexiform  branches,  which  have  a  ganglionic  aspect,  surround  the  vis- 
ceral arteries,  and  are  subdivided  with  them  to  enter  the  substance  of  the  viscera. 

It  follows,  then,  from  what  has  been  just  stated,  that  the  great  sympathetic  is  neither 
a  continuous  nerve,  differing  from  other  nerves  only  by  having  enlargements,  as  was  be- 
lieved by  the  older  anatomists,  who  described  the  right  and  left  sympathetic  as  cnnsti- 


766  NEUROLOGY. 

tuting  a  special  pair ;  nor  is  it,  as  Bichat  conceived,  a  linear  series  of  small  nervous 
centres  or  little  brains,  which  give  off  in  all  directions  connecting  filaments,  both  to  the 
spinal  and  to  the  visceral  nerves  ;  it  is  a  series  of  ganglia  connected  with  one  another 
in  their  action,  and  originating  from  each  of  the  spinal  nerves  given  off  from  the  cerebro- 
spinal axis.  It  does  not  arise  from  the  sixth  cerebral  nerve,  nor  from  the  vidian  or 
carotid  filaments,  more  than  from  any  other  spinal  nerve  ;  but  it  takes  its  origin  from 
the  whole  spinal  cord  ;  and  if  it  does  not  diminish  in  size  as  it  recedes  from  the  brain, 
but  even  increases  at  some  points,  this  is  because  it  receives  new  filaments  of  origin 
during  its  course. 

According  to  an  ingenious  hypothesis,  which  is  fully  confirmed  by  anatomical  facts, 
the  viscera,  which  receive  their  nerves  from  the  ganglia  of  the  great  sympathetic,  derive 
their  principle  of  action  from  the  whole  spinal  cord,  so  that  an  affection  of  one  nerve,  or 
of  one  visceral  ganglion,  must  affect  the  whole  ganglionic  system,  in  consequence  of  the 
intimate  connexions  between  all  the  ganglia ;  and  also  the  cerebro-spinal  system,  from 
the  connexions  between  the  sympathetic  ganglia  and  the  spinal  cord.  It  would  follow 
from  this,  that  the  sympathetic  and  the  splanchnic  ganglia  together  constitute  one  vast 
plexus,  which  connects,  in  an  intimate  manner,  the  several  viscera  with  each  other  and 
with  the  rest  of  the  body.  This  mutual  dependance  and  sympathy  is  the  chief  charac- 
teristic of  the  organs  of  nutritive  life,  that  is  to  say,  of  the  organs  which  receive  their 
nervous  filaments  from  the  splanchnic  and  sympathetic  ganglia. 

Structure  of  the  JVerves. 

Prochaska  was  the  first  to  throw  any  light  upon  the  obvious  structure  of  the  nervous 
cords,  and  to  prove  that  they  consisted  of  true  plexuses.  Reil,  not  being  contented  with 
noticing  the  plexiform  arrangement  of  the  nervous  cords,  endeavoured  especially  to  de- 
termine their  structure  ;  and  he  failed  only  because  he  selected  the  optic  nerve  as  the 
type  of  the  other  nerves,  whereas  its  structure  happens  to  be  exceptional. 

Each  nerve  consists  of  a  plexus  enveloped  in  a  common  fibrous  sheath.  If  this  sheath 
be  opened,  and  the  small  nervous  cords  contained  within  it  are  spread  out  by  tearing  the 
cellular  tissue,  it  is  found  that  these  small  cords,  which  at  first  seem  to  be  parallel  and 
in  juxtaposition,  anastomose  in  a  great  number  of  ways,  so  as  to  form  an  extremely 
complicated  plexus.  It  is  also  seen  that  the  cords  are  of  unequal  size,  not  only  in  the 
same  nerve,  but  also  in  different  nerves  ;  they  are  smallest  in  the  branches  of  the  great 
sympathetic  and  pneumogastric,  and  are  largest  in  the  nerves  of  the  arm  and  in  the  great 
sciatic  nerves. 

On  spreading  out  a  nerve,  with  its  component  cords  separated  from  each  other,  upon 
a  plate  of  wax,  and  keeping  those  cords  asunder  by  pins  stuck  at  intervals,  the  absolute 
impossibility  of  following  them  through  their  successive  subdivisions,  and  the  multiplicity 
of  their  combinations,  will  become  quite  apparent. 

The  nerves  consist  essentially  of  two  parts,  viz.,  the  nervous  matter  properly  so  called, 
and  its  envelope  oi  fibrous  sheath,  which  has  been  called  the  neurilemma. 

There  is  a  common  neurilemma  or  common  fibrous  sheath  for  each  nerve.  Besides 
this,  each  small  nervous  cord  and  each  fibre  is  provided  with  a  proper  sheath  or  neuri- 
lermna.  The  neurilemmatic  canals  divide,  subdivide,  and  anastomose  like  the  small 
nervous  cords  themselves. 

The  neurilemmatic  canals  are  composed  of  fibrous  tissue :  their  shining  aspect  (which 
has  caused  them  to  be  frequently  mistaken  for  tendons),  their  strength,  their  inextensi- 
bility,  their  low  degree  of  vitality,  in  fact,  all  their  characters,  clearly  prove  their  fibrous 
nature  and  exclusively  protective  function.* 

The  neurilemma  of  the  nerves  is  continuous  with  the  neurilemma  of  the  spinal  cord. 

Nervous  Matter. — If,  as  was  shown  by  Reil,  a  nerve  be  immersed  in  diluted  nitric  acid. 
Its  neurilemma  will  be  dissolved  (rendered  transparent),  while  its  nervous  matter  will 
become  remarkably  dense  and  opaque.  We  shall  hereafter  see  how  valuable  is  this 
double  property  of  acids  in  their  action  upon  nerves  for  determining  the  true  character 
of  fibres  supposed  to  be  nervous.  In  a  nerve  thus  prepared,  it  is  seen  most  clearly,  that 
the  nervous  filaments  of  which  it  is  composed  are  continually  anastomosing  by  loops  or 
at  certain  angles  ;  and  that  the  addition  of  one  set  of  filaments  to  the  trunk  of  the  nerve, 
or  the  separation  of  others  from  it,  necessarily  interrupts  the  chain  of  their  relations  at 
the  very  point  where  it  seemed  possible  to  ascertain  them,  so  that,  after  every  few  inches, 
the  component  parts  of  a  nerve  are  completely  changed. 

What  is  the  structure  of  the  nervous  matter  1  It  is  not  a  pulp,  but  is  composed  of 
pencils  of  exceedingly  fine  filaments,  which  may  be  compared  to  the  fibres  of  raw  silk  : 
these  filaments  are  parallel  and  in  juxtaposition ;  they  are  free  throughout  the  whole 
length  of  the  nerve,  and  may  be  distinctly  separated  from  each  other ;  when  not  stretched, 
they  are  flexuous  like  a  waved  line.  Each  nervous  filament  reaches  the  entire  length 
of  the  nerve.     In  each  nerve,  the  filaments  of  which  the  fibres  are  composed  pass  con- 

*  It  may  bo  said  that  the  neurilemma  owes  its  fitness  as  a  protecting  organ  as  well  to  its  low  vitality  as  to 
its  strength.  This  low  degree  of  vitality  of  the  neurilemma  is  the  cause  why  nerves  are  constantly  seen  oasn 
ing  through  inflamed  or  degenerated  parts  without  being  aflTected  themselves. 


STRUCTURE  OF  THE  NERVES.  767 

tinually  from  one  fibre  to  another,  and  enter  into  an  immense  number  of  combinations, 
without  ever  becoming  blended  together. 

This  structure,  which  is  so  evident  in  a  nerve  hardened  by  nitric  acid,  is  not  less  dis- 
tinct in  nerves  which  have  undergone  no  preparation.*  On  puncturing  the  neurilemma, 
the  nervous  matter  protrudes  through  the  opening,  precisely  in  the  same  way  as  the 
substance  of  the  spinal  cord  protrudes  under  similar  circumstances.  On  dividing  the 
neurilemma  along  the  whole  length  of  the  nerve,  the  nervous  matter  appears  like  long, 
parallel  filaments,  of  a  milk-white  colour,  which  float  in  water  if  the  nerve  be  immersed 
in  that  fluid. 

Every  nervous  filament  (and  this  is  a  fundamental  point  in  their  anatomy)  has  its 
central  extremity  in  the  cerebro-spinal  axis,  and  its  peripheral  extremity  at  its  point  of 
termination.  During  the  whole  of  its  long  course,  it  only  enters  into  new  combinations 
without  ever  being  interrupted. 

Continuity  is  a  law  of  the  structure  of  the  nervous  filaments  A 

Can  the  nerves  be  injected  1 

The  doctrine  of  a  nervous  fluid,  which  so  long  prevailed  in  the  schools,  led  physiolo- 
gists to  admit  the  existence  of  canals  for  the  circulation  of  this  fluid.  Several  experi- 
mentahsts  stated  that  they  had  collected  the  nervous  fluid,  and  they  even  described  its 
properties  ;  and  anatomists  instituted  no  researches  to  confirm  or  refute  these  asser- 
tions. Malpighi  himself,  who,  in  reference  to  the  study  of  anatomy,  carried  to  such  an 
extent  that  system  of  philosophical  skepticism  which  has  completely  revolutionized  all 
science,  believed  that  he  saw  the  nervous  fluid  escape  from  the  cut  end  of  a  nerve,  like 
a  glutinous  juice,  which  he  compared  to  spirits  of  turpentine. t 

Reil  and  some  others  have  injected  the  neurilemma.  Reil  describes  a  very  ingenious 
method  of  injecting  the  optic  nerve,  which  consists  in  opening  the  transparent  cornea, 
and  injecting  mercury  into  the  globe  of  the  eye  :  the  mercury  passes  through  the  fora- 
mina, which  transmit  the  filaments  of  the  optic  nerve  at  the  point  where  these  become 
continuous  with  the  retina. 

Such  was  the  state  of  our  knowledge  when  Bogros,  prosector  to  the  Faculty,  having 
accidentally  punctured  a  nerve  with  the  tube  of  a  mercurial  injecting  apparatus,  observ- 
ed that  the  mercury  ran  along  the  punctured  nervous  fibre,  and  also  into  the  adjacent 
nervous  fibres  ;  he  repeated  and  varied  his  experiments  in  a  great  number  of  ways,  and 
soon  published  a  memoir,  in  which  he  formally  announced  as  a  demonstrated  fact  that, 
in  each  nervous  fibre,  there  was  a  central  caned  capable  of  being  injected  ;  and,  in  his 
enthusiasm  at  his  discovery,  he  thought  that  he  had  realized  the  desire  of  Ruysch,1:  and 
that  he  could  henceforth  trace  the  nerves  to  their  very  finest  terminations. 

The  work  of  Bogros  was  in  general  received  with  little  favour,  and,  I  think,  has  not 
been  estimated  at  its  real  worth.  Having  renewed  his  experiments,  I  have  arrived  at 
the  following  result :  If,  with  a  pair  of  blunt  pincers,  a  nervous  fibre  be  raised  from  the 
centre  of  the  nerve  to  which  it  belongs  (from  the  middle  of  the  median  nerve,  for  exam- 
ple), and  if  the  tube  of  the  lymphatic  injecting  apparatus  be  inserted  accurately  into  its 
centre,  the  mercury  will  be  seen  to  run  by  jerks,  either  downward  or  upward,  along  the 
centre  of  the  nervous  fibre,  and  to  pass  into  a  variable  number  of  the  adjacent  fibres ;  if 
the  injection  be  a  successful  one,  the  greater  number  of  the  fibres  of  the  nerve  will  be 
injected  throughout  their  whole  length.  Gentle  pressure  with  the  finger,  or  with  the 
handle  of  the  scalpel,  greatly  facilitates  the  progress  of  the  mercury  ;  but  it  often  hap- 
pens that  the  parietes  of  the  canal  through  which  the  mercury  is  passing  yield  at  some 
point,  a  rupture  ensues,  and  the  fluid  is  extravasated. 

When  the  nervous  fibre  has  not  been  punctured  in  the  centre,  the  mercury  is  seen  to 
run  along  the  injected  fibre,  and  even  into  some  of  those  near  it ;  but  the  mercurial  col- 
imin  is  never  regular  ;  it  does  not  occupy  the  centre  of  the  fibre,  but  only  one  side  of  it ; 
and  it  is  soon  extravasated  into  the  neurilemmatic  sheath,  which  in  a  short  time  bursts. 

This  second  kind  of  injection,  which  may  be  made  at  wUl  by  puncturing  the  fibre  su- 

*  I  have  also  examined  this  structure  in  living  animals,  while  endeavouring  to  determine  the  insensibility 
of  the  neurilemma  and  the  sensibility  of  the  nervous  filaments. 

t  [The  nervous  filaments  (primitive  fibres  of  MUUer)  are  simple  tubes,  containing  a  thread  of  a  soft,  semi- 
transparent  substance  ;  they  are  continuous  with  the  white  fibres  of  the  brain  and  spinal  cord  at  the  apparent 
origin  of  the  nerves.  The  primitive  fibres  of  the  nerves  resemble  those  of  the  brain  and  cord  in  the  nature  of 
their  contents,  but  they  are  larger,  and  their  tubular,  homogeneous  sheath  is  much  more  distinct,  and  is  firmer, 
so  that  they  do  not  become  varicose.  The  olfactory,  optic,  and  auditory  nerves,  however,  are  exceptions  to 
this  rule  ;  their  fibres  resembling  those  of  the  brain  and  cord,  in  their  size,  delicacy,  and  liability  to  become 
varicose.  No  differences  have  been  observed  between  the  fibres  of  the  other  cranial  and  spinal  nerves,  nor  yet 
between  those  of  the  motor  and  sensory  roots.  The  sympathetic  nerve,  and  all  which  receive  fibres  from  it, 
contain,  besides  the  ordinary  nervous  fibres,  a  greater  or  less  number  of  jointed  fibres  (gray  fibres,  MUUer ; 
organic  nervous  fibres,  Schmann  ;  cellular  tissue,  Valentin),  exactly  like  those  found  in  the  ganglia  and  in  the 
gray  matter  of  the  brain  and  spinal  cord.] 

t  But,  as  Haller  remarks,  Malpighi  only  saw  this  upon  cutting  through  the  Cauda  equina,  and  never  ob- 
served it  in  the  section  of  any  other  nerves  ;  now,  it  is  extremely  probable  that  he  saw  merely  the  serous  fluid 
which  is  most  commonly  found  in  the  lower  infondibuliform  portion  of  the  spinal  dura  mater :  "  Quam  yehe- 
menter  suspicor  eum  clarum  virum  humorem  vidisse  viscidurn,  quo  infundibulum  durie  membrane  spinalis  fre- 
ciuentissime  plenum  est,  ct  qui  idem  in  spinam  bifidam  auctus  aliit." — (Haller,  Elem.  Physiol.,  t.  iv.,  p.  197.) 

t)  Ruysch  sa.d  that  he  should  have  nothing  to  desire  if  he  could  succeed  in  injecting  the  nerves  as  he  had 
done  the  vessels. 


768  NEUROLOGY. 

perficially,  differs  essentially  from  the  former  one,  obtained  by  introducing  the  pipe  into 
the  centre  of  the  fibre.  In  the  latter  case,  the  small  column  of  mercury  is  uniform  and 
regular,  and  its  metallic  lustre  is,  as  it  were,  observed  ;  the  fluid  runs  rapidly  ;  the  ner- 
vous canal  is  less  easily  ruptured ;  and,  when  this  does  happen,  it  is  preceded  by  a  pro- 
trusion of  the  nervous  matter  ;  then  the  mercury  is  extravasated  into  the  neurilemmatic 
sheath,  and  it  pursues  the  same  course  as  it  would  have  taken  if  the  nervous  fibre  had 
been  punctured  superficially  in  the  first  instance. 

Where  do  the  injections  pass  in  these  two  cases  ■?  In  the  second  method,  that  is  to 
say,  when  the  nerve  is  punctured  superficially,  it  is  the  neurilemma  that  is  injected.  But 
in  the  method  of  central  injection,  is  the  nervous  matter  itself  injected  1  Bogros  be- 
lieved that  it  was,  and  he  even  asserted  that  he  had  seen  a  central  canal  with  the  naked 
eye  ;  but  no  such  canal  exists  ;  and  the  one  which  he  showed  after  desiccation  of  an  in- 
jected nerve  was  artificially  made,  as  we  shall  immediately  find.  How,  indeed,  can  we 
admit  the  existence  of  a  canal  in  nervous  matter,  which  we  have  shown  to  consist  of  a 
pencil  of  parallel  and  juxtaposed  filaments'? 

If,  therefore,  in  the  central  injectiouj  the  mercury  neither  enters  into  the  nervous  mat- 
ter, nor  is  contained  in  the  neurilemma,  where  is  it  situated  1  Is  it  in  lymphatic  ves- 
sels 1  We  do  not  know;  for  lymphatics  have  not  been  shown  by  any  one.  Are  they 
arteries  or  nerves  1  To  this  it  may  be  answered,  that  the  bloodvessels  do  not  follow  the 
direction  of  the  nerves. 

All  this  is  explained  by  the  following  fact :  each  nervous  fibre,  besides  its  common 
neurilemmatic  sheath,  has  also  a  proper  sheath,  in  contact  with  the  neurilemma  by  its 
outer  surface,  and  with  the  bundle  of  nervous  filaments  by  its  inner  surface,  which  is 
smooth  and  moist.  This  sheath  may  be  demonstrated  by  cutting  a  nerve  across,  and 
seizing  one  of  the  tufts  which  project  beyond  the  retracted  neurilemma  ;  a  nervous  fibre 
can  then  generally  without  effort  be  drawn  out  several  inches,  having  a  smooth  surface, 
and  being  completely  freed  from  its  common  neurilemma.  Now  this  fibre  consists  not 
only  of  nervous  matter,  but  also  of  a  proper  sheath  perfectly  distinct  from  the  neurilem- 
ma. It  may  now  be  injected,  and  will  then  present  all  the  characters  of  the  central  in- 
jection already  mentioned  ;  and,  upon  examining  it  with  a  lens,  it  will  be  seen  that  the 
nervous  filaments  of  which  it  is  composed  are  regularly  distributed  around  the  column 
of  mercury. 

It  follows,  then,  that,  in  the  central  injection  of  a  nerve,  it  is  neither  the  neurilemma, 
nor  the  nervous  matter,  nor  the  vessels  that  are  injected,  but  the  proper  sheath  of  each 
nervous  fibre  ;  and  that  the  passage  of  the  injection  from  one  fibre  to  a  great  number  of 
others  depends  on  the  canals  formed  by  the  proper  sheaths  anastomosing  with  each  other. 

I  shall  farther  remark,  that  in  this  injection  the  mercury  evidently  penetrates  into  a 
regular  canal,  and  not  into  one  produced  by  its  own  weight,  for  a  column  of  a  few  lines 
IS  sufficient  for  the  purpose. 

Again,  the  mercury  runs  more  easily  from  the  peripheral  towards  the  central  extrem- 
ity of  a  nerve  than  in  the  opposite  direction,  and  when  the  injection  is  successful,  the 
spinal  ganglia  are  filled  with  the  mercury,  which  is  then  either  extravasated  into  the  cav- 
ity of  the  dura  mater,  or  escapes  by  the  veins.  If  it  be  asked  why  the  mercury  does  not 
pass  into  the  anterior  and  posterior  roots  of  the  nerves  1  I  should  answer,  that  it  is  not 
certain  that  the  fibres  of  these  roots  have  any  proper  sheaths  ;  or,  if  so,  they  are  very 
readily  lacerated.  As  to  the  passage  of  the  mercury  from  the  nervous  ganglia  into  the 
veins,  it  is  probable  that  the  proper  sheaths  terminate  in  the  ganglia,  so  that  the  mercu- 
ry is  extravasated  into  the  tissue  of  which  the  ganglia  consist. 

Injections  afford  a  good  means  of  tracing  the  nervous  filaments  into  the  substance  ot 
organs.  An  injection  thrown  into  the  lingual  branch  of  the  fifth  nerve  penetrates  as  far 
as  the  papillae  of  the  tongue. 

Structure  of  the  Ganglia. 

Meckel,  in  his  excellent  monograph  upon  the  fifth  pair,  advanced  the  opinion  that  the 
nerves  divided  in  the  ganglia  into  a  multitude  of  fibres  which  are  intended  for  a  great 
number  of  parts. 

Zinn  (Acad.  Berlin,  1755)  said  that  the  nerves  not  only  divided  within  the  ganglia  into 
a  great  number  of  fibres,  and  were  directed  by  them  from  the  centre  to  the  circumference, 
but  that  they  were  also  mingled  and  combined  in  the  ganglia  in  such  a  manner  that  a 
great  number  of  fine  fibres  united  into  a  smaller  number  of  fibres  of  greater  diameter. 

But  this  doctrine,  however  specious  it  may  be,  not  resting  upon  any  anatomical  fact, 
was  rejected  by  Haller.  Scarpa  undertook  a  series  of  researches  in  order  to  render  our 
knowledge  more  complete  regarding  this  subject.  Instead  of  boiling  the  ganglia  or  ma- 
cerating them  in  vinegar,  urine,  and  other  hquids,  Scarpa  was  contented  with  macera- 
ting them  in  pure  water  frequently  renewed — a  method  practised  by  Ruysch  in  his  del- 
icate investigations  ;  by  means  of  this  simple  proceeding,  he  was  able  to  demonstrate 
that  the  ganglia  are  formed  by  a  number  of  nervous  filaments  sun'ounded  by  cellular  tis- 
sue, and  by  a  gray  matter  which  is  destroyed  by  maceration.* 

*  [The  gray  mattf  r  of  the  ganglia  consists,  like  that  of  the  brain  and  spinal  cord,  of  reddish  nucleated  glob- 


DESCRIPtieSf   df  "THE   NERVES. 

He  carried  his  researches  not  only  into  the  anatomy  of  the  spinal,  but  also  into  that 
of  the  visceral  ganglia,  and  he  discovered  a  wonderful  uniformity  in  the  structure  of  the 
one  and  the  other.  He  compared  their  structure  to  that  of  the  plexuses  ;  both  of  them 
receive  nerves  from  all  sides,  which  nerves  are  then  intermixed  without  becoming  uni- 
ted ;  and  both  generally  give  off  a  greater  number  of  nerves  than  have  assisted  in  their 
formation. 

The  injection  of  the  nervous  ganglia  from  the  nerves  has  enabled  me  to  discover  that 
these  ganglia  have  a  precisely  similar  structure  to  that  ofthe  lymphatic  glands ;  they 
are  composed  of  cells  communicating  with  each  other,  and  among  which  the  nervous 
fibres  are  scattered. 

In  attempting  to  draw  a  comparison  between  the  nervous  plexuses,  anastomoses,  and 
ganglia,  it  might  be  said  that  in  the  plexuses  there  was  an  exchange  of  nervous  cords, 
in  the  anastomoses,  an  exchange  of  nervous  fibres,  and  in  the  ganglia,  an  exchange  of 
nervous  filaments. 

Preparation  ofthe  Merves. 

For  dissecting  the  nerves,  a  very  emaciated  subject,  either  young  or  old,  should  be 
chosen.     Old  wasted  subjects  appear  to  me  at  least  as  favourable  as  young  subjects. 

The  dissection  of  the  spinal  nerves  is  easy.  Such  is  not  the  case  with  the  cranial 
nerves,  the  dissection  of  which  is  undoubtedly  the  most  difficult  part  of  practical  anat- 
omy. In  order  to  faciUtate  the  study  of  these  nerves,  and  to  aid  in  the  distinction  ofthe 
nervous  filaments  from  small  vessels  and  portions  of  fibrous  tissue  with  which  they  are 
often  confounded,  I  am  in  the  habit  of  submitting  the  head  to  the  action  of  dilute  nitric 
acid.  After  having  macerated  it  for  some  time  in  this  acidulated  fluid,  I  immerse  the 
Pfepafation  in  pure  water,  which  I  renew  from  time  to  time :  the  tissues  generally,  as 
/well  as  the  neurilemma,  become  perfectly  transparent,  and  like  jelly ;  the  nervous  mat- 
/^  ter  alone  remains  whiter  and  more  consistent,  and  then  all  error  becomes  impossible. 
Besides,  the  bones,  when  thus  deprived  of  their  phosphate  of  lime,  may  be  cut  like  the 
soft  "parts.  In  this  way  I  have  succeeded  in  separating  the  entire  cerebro-spinal  nervous 
system  from  the  other  organs,  retaining  the  great  sympathetic  in  connexion  with  the 
rest  of  the  nervous  system. 


DESCRIPTION  OF  THE  NERVES. 

General  Remarks. — Division  into  Spinal,  Cranial,  and  Sympathetic  Nerves. 

The  nerves  are  divided  into  two  very  distinct  sets  :  the  cerebro-spinal  nerves,  whicn 
have  their  origin  or  central  extremity  in  the  spinal  cord  or  its  cranial  prolongations : 
these  are  the  nerves  of  relation  or  of  animal  life  ;  and  the  ganglionic  nerves,  or  nerves  of 
the  great  sympathetic,  which  end  in  or  emanate  from  certain  ganglia :  these  belong  to  the 
system  of  nutrition  or  of  organic  life. 

The  cerebro-spinal  nerves  are  divided  into  the  spinal  or  rachidian,  and  the  cranial 
nerves :  the  first  consist  of  all  those  which  emerge  from  the  inter-vertebral  foramina  ;* 
the  second,  so  improperly  termed  the  cerebral  or  encephalic  nerves,  emerge  from  the 
foramina  at  the  base  of  the  cranium. 

As  the  line  of  demarcation,  which  seems,  at  first  sight,  to  separate  the  cranium  from 
the  spinal  column,  disappears  on  an  analytical  study  ofthe  scull  and  on  a  comparison  of 
it  with  the  vertebrae,  so  it  will  be  found  that  the  cranial  nerves,  notwithstanding  their 
apparent  irregularity,  approach,  in  many  respects,  to  the  simplicity  and  regularity  of  the 
spinal  nerves.  From  such  a  comparison  of  the  cranial  with  the  spinal  nerves  we  shall 
derive  the  general  principle,  that  the  situation  at  which  the  nerves  emerge  from  their 
osseous  cavities  is  altogether  of  secondary  importance,  while  the  fundamental  points  in 
their  anatomy  are  the  exact  situation  of  their  central  extremity,  and  their  mode  of  distri- 
bution to  their  peripheral  extremity ;  we  shall  also  find  that  the  only  ratiofial  basis  of  a 
good  classification  of  the  nerves  must  be  derived  from  the  consideration  of  their  origin. 

In  my  opinion,  the  only  difference  between  the  cranial  and  spinal  nerves  is,  that  the 
former  arise  from  the  medulla  oblongata  and  its  cranial  prolongations,  while  the  latter 
arise  from  the  spinal  cord  below  the  medulla  oblongata.  Just  as  in  the  osteological  di- 
vision of  this  work  I  have  described  the  vertebra  before  the  cranium,  so  I  shall  now  de- 
scribe the  spinal  before  the  cranial  nerves  ;  this  slight  modification  in  the  order  gener- 
edly  adopted  will  enable  the  student  to  pass  from  the  simple  to  the  complex,  and  to  defer 
the  study  of  the  very  complicated  nerves  of  the  cranium  until  he  has  been  accustomed 
to  the  dissection  and  examination  of  other  nerves. 

The  following  is,  therefore,  the  order  I  shall  adopt  in  describing  the  nerves  :  the  spi- 
nal nerves,  the  cranial  nerves,  the  ganglionic  or  visceral  nerves. 

ules,  and  of  grray,  jointed  fibres,  which  surround  and  adhere  to  the  globules,  and  which  are  most  abundant  in 
the  ganglia  of  the  sympathetic.     The  white  fibres  in  the  ganglia  are  like  those  of  the  nerves  with  which  they 
are  continuous ;  they  interlace  among  the  globules,  but  do  not  anastomose  ;  it  has  been  supposed  that  some 
wh'te  fibres  may  originate  or  terminate  in  the  ganglia,  but  this  is  not  established.] 
*  It  will  be  recollected  that  we  have  included  the  sacral  foramina  among  the  invertebral. 

5E 


7TO  NEUROLOGY. 

THE  SPINAL  NERVES.  .  ..      -  . .      • 

Enumeration  and  Classification. — The  Central  Extremities  or  Origins  of  the  Spinal  Nerves 
— Apparent  Origins  —  Deep  or  Real  Origins.  —  The  Posterior  Branches  of  the  Spinal 
Nerves — Common  Characters — the  Posterior  Branches  of  the  Cervical  Nerves,  their  Com- 
mxtn  and  Proper  Characters — the  Posterior  Branches  of  the  Dorsal,  Lumbar,  and  Sacral 
Nerves. — The  Anterior  Branches  of  the  Spinal  Nerves — their  General  Arrangement. 

The  number  of  the  spinal  nerves,  that  is  to  say,  of  the  nerves  which  peiss  through  the 
inter-vertebral  foramina,  including  the  sacral  foramina,  is  entirely  dependant  on  the 
nimiber  of  the  vertebrae.* 

There  are  eight  pairs  (1  to  8,fg.  268)  of  cervical  nerves,  including  the  sub-occipital ; 
twelve  of  dorsal  (9  to  20) ;  five  of  lumbar  (21  to  25) ;  and  six  of  sacral  nerves  (26  to  31) ; 
in  all,  thirty-one  pairs. 

They  all  have  certain  characters  in  common ;  and  there  are  also  characters  proper  to 
certain  regions,  and,  lastly,  characters  proper  to  each  nerve. 

We  shall  proceed  to  examine,  under  these  three  points  of  view,  the  central  extrem- 
ity, the  course,  and  the  termination  of  the  spinal  nerves. 

The  Central  Extremities  or  Origins  of  the  Spinal  Nerves. 

The  Apparent  Origins  of  the  Spinal  J^erves. 

Dissection. — The  same  as  that  of  the  spinal  cord. 

Common  Characters. 

There  are  very  close  analogies,  and  only  slight  differences,  between  the  different  spi- 
nal nerves,  in  regard  to  their  origin  and  course  within  the  spinal  canal.  This  circum- 
stance, added  to  the  fact  that  the  same  dissection  is  required  to  expose  the  origins  of 
the  whole  series  of  spinal  nerves,  has  appeared  to  me  a  sufBcient  reason  for  including 
them  all  in  one  common  description.  Such  a  plan,  the  object  of  which  is  to  study  anal- 
ogous parts  by  comparison,  is  infinitely  preferable  to  one  in  which  the  origin  of  each 
pair  of  nerves  is  separately  described. 

The  spinal  nerves  arise  from  the  spinal  cord  by  a  double  row  of  filaments,  or  by  two 
series  of  roots.  These  roots  are  distinguished  into  the  anterior  (a  a,  Jig.  267),  which 
come  off  from  each  side  of  the  anterior  surface  of  the  cord,  and  the  posterior  (h  b),  which 
come  off  also  from  each  side  of  the  posterior  surface.  The  latter  are  also  named  the 
ganglionic  roots,  because  they  are  more  particularly  connected  with  the  spinal  nervous 
ganglia  {b  b). 

The  ligamentum  denticulatum  (c  c)  is  situated  between  these  two  series  of  roots. 

Immediately  after  leaving  the  cord,  both  the  anterior  and  posterior  roots  are  collected 
Into  a  number  of  groups  corresponding  to  the  number  of  the  spinal  nerves  ;  the  nervous 
cords  of  which  each  group  consists  converge  towards  each  other,  the  superior  cords  de- 
scending to  meet  the  inferior,  which  is  soon  accomplished  from  the  latter  being  less  ob- 
lique in  their  direction.  It  follows,  therefore,  that  the  filaments  of  each  root,  situated 
one  above  the  other,  widely  separated  from  each  other  on  the  inside,  and  approximated 
on  the  outside,  represent  a  triangle,  the  general  inclination  of  which  to  the  axis  of  the 
cord  varies  in  each  particular  region.  Not  unfrequently  the  filaments,  especially  those 
of  the  anterior  roots,  form  two  secondary  groups. 

As  they  are  about  to  enter  the  separate  fibrous  canal  formed  for  them  by  the  dura 
mater,  the  fibres  of  each  of  the  anterior  roots,  and  also  those  of  each  posterior  root,  are 
collected  into  a  flattened  cord.  There  is  one  fibrous  canal  for  each  cord  of  the  anterior 
roots,  and  another  for  each  cord  of  the  posterior  roots.  The  arachnoid  membrane, 
which  forms  a  common  funnel-shaped  sheath  for  both  roots  of  each  spinal  nerve,  is  re- 
flected from  them  at  the  points  where  they  enter  the  fibrous  canals  of  the  dura  mater, 
to  which  the  nervous  cords  are  rather  firmly  attached. 

Although  the  corresponding  groups  of  anterior  and  posterior  roots  approach  each  other 
to  pass  through  the  fibrous  canals  of  the  dura  mater,  there  is  never  the  slightest  com- 
munication between  them.  It  is  curious  to  see  the  long  and  numerous  cords  or  fila- 
ments which  constitute  the  cauda  aquina  running  parallel  to  each  other  without  any  an- 
astomoses, while,  as  soon  as  they  emerge  from  the  spinal  canal,  their  communications 
are  almost  continual. 

Communications  between  the  filaments  of  the  same  series,  whether  anterior  or  pos- 
terior, are  not  rare ;  they  take  place  in  several  different  ways :  thus,  sometimes  two 
filaments  belonging  to  the  same  nerve  unite,  sometimes  the  filaments  of  two  different 
nerves  are  combined,  and  at  others,  again,  a  filament  intermediate  to  two  nerves  bifur- 
cates and  is  divided  between  them. 

Moreover,  the  oblique  direction  of  the  roots  of  the  spinal  nerves,  and  the  variable 
length  of  their  course  within  the  spinal  canal,  are  the  necessary  consequences  of  the 

*  This  relation  between  the  number  of  the  spinal  nerves  and  the  number  of  the  vertebrs  prevails  through- 
.out  the  whole  series  of  vertebrate  animals  ;  and,  accordingly,  there  are  about  sixty  spinal  nerves  in  certain 
Hsuunmalia,  and  several  hundred  in  some  serpents. 


APPARENT    ORIGINS    OP    THE    NERVES.  wl^ 

relative  shortness  of  the  cord,  which,  as  it  terminates  opposite  the  first  lumhaTvertobra. 
cannot  give  origin  to  adl  the  nerves  opposite  the  inter-vertebral  foramina,  through  which 
they  have  to  pass.* 

The  differences  between  the  anterior  and  posterior  roots  may  be  collected  under  the 
following  heads  : 

The  anterior  roots  arise  nearer  to  the  median  line  than  the  posterior  ;  they  approach 
nearer  and  nearer  to  that  line,  towards  the  lower  part  of  the  cord,  so  tba  in  this  situa- 
tion they  arise  from  each  side  of  the  median  fissure. 

While  all  the  posterior  roots  are  given  off  from  a  longitudinal  furrow  of  gray  sub- 
stance, from  which  they  never  deviate,  the  anterior  roots  arise  somewhat  irregularly, 
and,  as  it  were,  confusedly,  from  a  small  white  column  about  half  a  line  in  breadth. 

In  regard  to  size,  the  posterior  roots,  taken  separately,  are  much  larger  than  their 
corresponding  anterior  roots  ;  besides  this,  the  filaments  of  the  posterior  roots  are  more 
numerous,  so  that  the  posterior  roots,  taken  together,  are  larger  than  the  anterior,  as 
Soemmering,  Chaussier,  and  Gall  have  very  well  established.  It  is  difficult  to  conceive 
how  some  authors  should  have  entertained  the  opinion  that  the  proportion  between  them 
is  just  the  reverse,  at  least  in  some  regions ;  this  error  has,  doubtless,  arisen  from  the 
varieties  which  exist  in  different  regions  of  the  medulla,  in  the  relative  sizes  of  the  an- 
terior and  posterior  roots,  but  which  are  never  such  as  to  give  the  advantage  in  point 
of  size  to  the  anterior  roots  :  opposite  the  inter-vertebral  foramina,  the  series  of  cords 
formed  by  the  anterior  roots  have  a  different  arrangement  from  those  formed  by  the  pos- 
terior roots. 

The  cord  formed  by  each  of  the  posterior  roots  immediately  swells  out  and  forms  an 
olive-shaped  ganglion,  which  is  called  a  vertebral  or  spinal  ganglion  {b  b,  Jig.  267).  Haase, 
and  then  Scarpa,  clearly  proved  that,  in  gener£il,  the  posterior  roots  alone  passed  into  the 
spinal  ganglia,  and  hence  they  are  often  denominated  the  ganglionic  roots :  the  spinal 
ganglia  are  situated  in  the  inter-vertebral  foramina,  those  of  the  sacral  region  are  en- 
closed in  the  sacral  canal. 

Though  it  is  generally  to  the  nervous  cord  which  emerges  from  this  ganglion  that  the 
cord  of  the  anterior  root  is  applied  and  united,  yet  I  would  hasten  to  observe,  that  the 
anterior  root  is  not  so  completely  unconnected  with  the  ganglion  as  is  commonly  stated  ; 
thus,  not  unfrequently  the  fibres  of  the  anterior  root  are  united  either  to  the  outer  end  or 
to  the  middle  of  the  ganglion ;  and,  moreover,  in  the  lumbar  and  sacral  regions  there  is 
half  a  ganglion  on  each  root. 

There  are  thirty  pairs  of  spinal  ganglia,  and  occasionally  thirty-one,  when  the  first 
pair  of  cervical  nerves  or  the  sub-occipital  nerves  are  provided  with  them :  the  size  of 
the  ganglia  bears  no  proportion  to  the  diameter  of  the  inter-vertebral  foramina,  but  de- 
pends on  the  number  and  size  of  the  filaments  of  origin  which  pass  into  them,  and  of  the 
nerves  which  are  given  off  from  them. 

The  cord  which  emerges  from  the  ganglion  is  cylindrical,  has  a  plexiform  structure, 
and  a  furrowed  aspect ;  it  is  impossible  to  ascertain  what  part  of  it  belongs  to  the  ante- 
rior and  what  to  the  posterior  root ;  it  gives  off  three  sets  of  branches  :  the  posterior 
spinal  branches,  which  supply  the  muscles  and  integuments  of  the  posterior  spinal  region  ; 
the  anterior  spinal  branches  (see  Jig.  268),  the  true  continuation  of  the  nerve,  which  are 
distributed  to  the  lateral  and  anterior  parts  of  the  trunk,  and  to  the  upper  and  lower  ex- 
tremities ;  and  the  ganglionic  spinal  branches,  which  pass  to  the  ganglia  of  the  great 
sympathetic  (/  i  u). 

The  ganglionic  branches  will  be  described  with  the  ganglia  of  the  great  sympathetic. 
As  the  posterior  branches  have  a  close  analogy  in  their  mode  of  distribution,  and  may 
be  exposed  in  the  same  dissection,  they  will  be  described  under  one  head. 

The  anterior  branches  being  destined  for  dissimilar  parts,  their  individual  distribution 
is  exceedingly  varied  and  complicated,  so  that  a  particular  description  is  requisite,  if  not 
of  the  anterior  branches  of  each  nerve,  at  least  of  those  of  the  several  sets  of  nerves. 

Such  are  the  characters  common  to  all  the  spinal  nerves  at  their  central  extremities, 
during  their  course  within  the  vertebral  canal,  and  at  their  exit  from  the  inter-vertebral 
foramina.    Let  us  next  examine  the  characters  proper  to  the  nerves  of  each  region. 

Proper  Characters  of  the  Apparent  Origins  of  the  Nerves. 

Proper  Characters  of  the  Cervical  Nerves. — The  roots  of  these  nerves  (1  to  8,  Jig.  268) 
are  much  less  oblique  than  those  of  the  other  spinsil  nerves.  The  first  cervical  nerve 
slopes  a  little  upward  and  outward,  like  the  cranial  veins,  which  it  resembles  in  this  re- 
spect. The  second  nerve  is  transverse ;  the  succeeding  nerves  slope  downward  and 
outward,  the  lowest  being  the  most  oblique  ;  but  their  obliquity  never  exceeds  the  depth 
of  a  single  vertebra. 

The  proportion  between  the  size  of  the  posterior  and  anterior  roots  is  as  3  to  1 ;  and 

*  Gall  believed  that  he  had  solved  this  question,  by  saying  that  the  length  and  obliquity  of  the  course  of 
he  spinal  nerves  is  a  necessary  result  of  the  erect  position  of  man.  It  is  certain  that  the  nerves  are  less  ob- 
ique  and  have  a  shorter  course  v^ithin  the  vertebral  canal  in  the  lovirer  animals;  but  this  difference  is  ex- 
plained by  the  greater  length  of  the  spinal  cord  in  them,  and  has  nothing  to  do  with  the  :itf;todf>. 


772  NEUROLOGY. 

this  difference,  which  is  much  greater  than  is  observed  in  any  other  region,  obtains  not 
only  in  reference  to  the  filaments  taken  altogether,  but  also  to  each  particular  filament. 

The  cervical  nerves  increase  rapidly  in  size  from  the  first  to  the  fifth,  and  then  main- 
tain the  same  size  to  the  eighth. 

The  first  cervical  nerve,  so  well  described  by  Asch,  has  some  peculiarities  :  its  pos- 
terior filaments  of  origin  are  much  less  numerous  than  the  anterior,  the  spinal  accessory 
of  Willis  appearing  to  supply  this  deficiency ;  it  is  also  frequently  without  a  ganglion.* 

Proper  Characters  of  the  Dorsal  Nerves. — Excepting  the  first,  which  has  all  the  charac- 
ters of  the  cervical  nerves,  the  roots  of  the  dorsal  pairs  of  nerves  (9  to  20)  present  the 
following  peculiarities  : 

A  small  number  of  filaments  or  roots ;  so  that,  with  the  exception  of  the  sacral,  the 
dorsal  are  the  smallest  of  all  the  spinal  nerves. 

Uniformity  in  the  number  of  the  filaments,  i  e.,  in  the  size  of  their  roots.  The  dorsal 
nerves  are  almost  of  equal  size,  the  twelfth  nerve  alone  being  somewhat  longer  than 
the  rest. 

A  considerable  interval  between  their  roots,  and  a  want  of  regularity  in  this  interval. 
Frequently  a  portion  of  the  spinal  cord,  from  eight  to  ten  lines  in  length,  gives  origin  to 
only  a  small  pair  of  nerves. 

A  more  marked  slenderness  of  the  filaments  of  origin  than  in  any  other  region. 

The  slight  disproportion  between  their  anterior  and  posterior  roots  when  compared 
filament  for  filament. 

The  direction  of  their  roots,  which  remain  in  contact  with  the  cord  for  some  distance, 
and  then  leave  it ;  this  circumstance  is  calculated  to  give  rise  to  errors  concerning  the 
precise  situation  of  their  origin. 

The  length  of  their  course  within  the  spinal  canal ;  this  length  is  equal  to  the  height 
of  at  least  two  vertebrae. 

Proper  Characters  of  the  Lumbar  and  Sacral  Nerves. — The  roots  of  these  nerves  form 
the  Cauda  equina ;  their  characters  are,  the  great  number  of  their  filaments  of  origin, 
which  exceeds  those  of  the  dorsal,  and  even  those  of  the  cervical  nerves. 

The  extreme  closeness  of  these  filaments,  which  form  an  uninterrupted  series. 

The  proportion  between  the  filaments  of  the  anterior  and  those  of  the  posterior  roots, 
which  is  as  2  to  1. 

The  uniformity  in  point  of  size  between  the  two  sets  of  filaments,  the  anterior  fila- 
ments, taken  individually,  being  as  large  as  the  posterior. 

The  continuance  of  the  origin  of  the  posterior  roots  to  take  place  at  the  groove,  while 
the  anterior  approach  nearer  and  nearer  to  the  median  line  towards  the  lower  part  of 
the  cord,  and  almost  touch  those  of  the  opposite  side. 

The  concurrence  of  both  the  anterior  and  posterior  roots  in  the  formation  of  the  spi- 
nal ganglia. 

The  almost  vertical  direction  of  the  roots,  a  character  common  to  both  the  lumbar 
and  sacral  pairs  of  nerves. 

The  singular  length  of  their  course  before  they  emerge  from  the  spinal  canal.t 

The  Real  Origins  of  the  Spinal  Jferves. 

The  apparent  central  extremity  or  origin  of  the  spinal  nerves  is  very  different  from  their 
real  central  extremity  or  real  origin.  On  examining  the  spinal  cord  of  an  adult,  for  the 
purpose  of  determining  this  important  point,  one  is  inclined  to  admit  that  the  point  of 
contact  between  any  nerve  and  the  cord  is  the  real  origin  of  the  nerve,  so  readily  can 
the  latter  be  separated  from  the  cord  without  leaving  any  trace  of  the  separation. 

It  has  even  been  stated  by  some  that  the  nerves  arise  from  the  neurilemma  of  the 
spinal  cord. 

Chaussier  believed  that  the  two  series  of  roots  arose  from  two  lateral  furrows,  one 
anterior  and  the  other  posterior ;  but  Gall  has  with  reason  regarded  these  furrows  as 
formed  by  pulhng  off  the  roots. 

Others  agree  with  the  older  anatomists  in  regarding  the  spinal  cord  as  a  large  nerve 
formed  by  the  junction  of  all  the  nervous  filaments  which  are  given  off  from  it.  But 
this  idea  is  refuted  by  the  fact  that  the  cord  does  not  progressively  diminish  in  size  from 
above  downward,  as  it  must  have  done  if  fonned  by  the  junction  of  the  roots  of  the  spi- 
nal nerves. 

The  ingenious  and  correct  observation  made  by  Vicq  d'Azyr,  that  the  gray  matter  is 
always  found  in  large  quantity  at  those  parts  from  which  a  great  number  of  nerves  ori- 
ginate, and  that  it  bears  a  proportion  to  the  number  of  these  nerves,  and  the  confirma- 
tory observations  of  Gall  and  Spurzheim,  seem  to  prove  that  the  nerves  originate  from 
the  gray  matter.    This  presumption  is  also  strengthened  by  the  consideration,  that  the 

*  According  to  the  principles  of  classification  which  I  have  already  stated,  I  should  range  the  spinal  acces- 
sory nerve  among  the  cervical  nerves,  because  it  originates  from  the  cervical  portion  of  the  spin;il  cord :  iu 
classing  it  among  the  cranial  nerves,  1  yield  to  general  usage. 

t  [Lastly,  the  situation  of  the  ganglia  of  the  sacral  nerves  within  the  sacral  canal,  and  of  the  lowest  of 
them  within  the  cavity  of  the  dura  mater.l 


POSTERIOR  BRANCHES  OP  THE  CERVICAL  NERVES         773 

central  gray  substance  of  the  cord  is  more  abundant  opposite  the  posterior  roots,  which 
are  the  larger,  than  opposite  the  anterior  roots,  which  are  the  smaller.  On  examining 
the  spinal  cord  of  an  adult  by  means  of  a  stream  of  water,  it  is  seen  that,  after  tearing 
away  the  filaments  of  the  nerves,  a  small  conical  depression  remains  where  each  fila- 
ment had  been  attached,  and  that  the  real  origin  of  the  filaments  is  not  in  this  depression, 
but  is  much  more  deeply  seated.  This  is  all  that  can  be  discovered  from  an  examina- 
tion of  the  spinal  cord  of  the  adult ;  but  in  the  foetus,  at  the  seventh  or  eighth  month,  a 
considerable  part  of  the  cord  is  semi-transparent,  so  that  the  already  white  filaments  by 
which  the  nerves  arise  can  be  traced  into  its  interior.  On  making  a  vertical  section 
transversely  through  the  spinal  cord  of  the  foetus,  just  level  with  the  commissure,  and 
then  directing  a  strong  light  on  the  surface  of  the  section,  it  will  be  seen  that  the  great 
number  of  very  delicate  filaments  of  which  the  anterior  and  posterior  roots  of  the  spinal 
nerves  are  composed  traverse  the  central  gray  matter,  are  arranged  like  the  teeth  of  a 
comb,  and  may  be  traced  into  the  posterior  median  columns  ;  these  small  filaments,  are, 
moreover,  all  parallel.  The  white  coimnissure  might  ahnost  be  regarded  as  the  com- 
missure of  these  nerves. 

This  view  is  very  different  from  that  of  Bellingeri,  who,  entertaining  certain  physio- 
logical ideas,  supposes  that  the  anterior  as  well  as  the  posterior  roots  of  the  spinal 
nerves  consist  of  three  sets  of  filaments,  some  of  which  come  from  the  surface  of  the 
cord,  others  from  the  interior  of  the  white  matter,  while  the  third  set  traverse  the  white 
matter,  so  as  to  reach  the  extremities  of  the  cornua  of  the  gray  substance. 

Lastly,  some  anatomists  agree  with  Santorini  in  believing  that  the  nerves  decussate 
at  their  origin ;  but  they  have  not  attempted  to  demonstrate  this. 

The  Posterior  Branches  of  the  Spinal  Nerves. 
Dissection. — Divide  the  integuments  from  the  external  occipital  protuberance  down  to 
the  coccyx.    Dissect  off  the  skin  over  the  spinous  processes  with  great  care,  especially 
opposite  the  trapezius.     Be  particularly  cautious  opposite  the  cellular  interval  between 
the  sjicro-lumbaJis  and  the  longissimus  dorsi. 

Common  Character's. 

The  posterior  branches  of  the  spinal  nerves,  which  are  generally  smaller  than  tne  anit- 
rior  branches,  emanate  from  the  plexiform  cords  which  form  the  continuation  of  the  cor- 
responding spinal  ganglia,  are  directed  backward,  and  immediately  pass  through  tlic  fora- 
mina, which  I  may  regard  as  posterior  inter-vertebral  foramina.*  These  branches  sub- 
divide into  several  twigs,  which  enter  the  great  cellular  intervals  between  the  long  mus- 
cles of  the  back,  and  are  distributed  to  the  muscles  of  the  integuments.  The  greatest 
uniformity  prevails  among  such  of  these  nerves  as  are  distributed  to  the  same  kinds  of 
organs,  and  their  differences  depend  on  peculiarities  in  the  parts  to  which  they  belong. 

We  shall  now  study  in  succession  the  posterior  branches  of  the  cervical,  dorsal,  and 
Iimibar  spinal  nerves. 

The  Posterior  Branches  of  the  Cervical  Serves. 

Common  Characters. 
All  the  posterior  branches  of  the  cervical  nerves  (« to  o',  fig.  300)  pass  transversely 
inward  between  the  complexus  and  the  semi-spinalis  colli,  haviiig  first  given  off  some 
very  small  twigs  :  having  reached  the  sides  of  the  posterior  cervical  ligament,  thoy  per- 
forate the  aponeurotic  attachments  of  the  trapezius  from  before  backward,  lie  close  be- 
neath the  skin,  and  are  directed  transversely  outward.  The  course  of  these  branches, 
therefore,  is  at  first  inward,  and  then  outward.  The  posterior  branch  of  the  first  cervi- 
cal nerve  is  the  only  one  which  presents  any  exception  to  these  general  characters. 

Proper  Characters. 
The  Posterior  Branch  of  the  First  Cervical  Nerve. 

The  posterior  branch  of  the  first  cervical  or  sub-occipital  nerve,  larger  than  the  anterior 
branch,  escapes  between  the  occipital  bone  and  the  posterior  arch  of  the  atlas,  on  the 
inner  side  of  the  vertebral  artery,  with  which  it  is  in  contact,  below  the  rectus  capitis 
posticus  major,  and  in  the  area  of  the  equilateral  triang'e  formed  by  that  with  tlie  two 
oblique  muscles  ;  in  this  situation  (i,  fig.  300)  it  is  concealed  by  a  large  quantity  of  fatty 
tissue,  which  renders  it  rather  difficult  of  dissection ;  and  it  immediately  divides  into 
several  branches,  which  may  be  arranged  into  the  internal,  which  go  to  the  great  and 
small  recti  muscles ;  extertud,  which  supply  the  great  and  small  oblique  muscles ;  and 
inferior  or  anastomotic,  which,  by  uniting  with  the  second  cervical  nerve,  assist  in  the 
formation  of  the  posterior  cervical  plexxts. 

The  branch  to  the  rectus  minor  passes  at  first  between  the  rectus  major  and  the  com- 
plexus, and  then  reaches  the  rectus  minor. 

*  Vide  Osteology  (vertebral  column  in  general).  Tiies--  n.ra  .j.  ;.  are  situated  between  the  transverse 
processes,  and  in  the  dorsal  region  are  cumpliti^d  on  ihu  .uiTs.ue  ii.      .     MsnKrior  costo-transverse  ligament. 


774  NEUROLOGY. 

The  principal  branch  for  the  inferior  oblique,  before  ramifying  in  that  muscle,  forms 
an  arch  or  loop,  which  has  been  well  described  by  Bichat. 

It  follows,  therefore,  that  both  of  the  recti  and  both  of  the  oblique  muscles  are  supplied 
by  the  first  cervical  nerve,  which  gives  no  filament  to  the  complexus,*  and  none  to  the  skin. 

The  Posterior  Branch  of  the  Second  Cervical  Nerve. 

This  is  the  largest  of  all  the  posterior  branches  of  the  cervical  nerves,  and  is  three  or 
four  times  larger  than  the  anterior  branch  of  the  same  nerve  ;  it  emerges  («■,  fig.  300) 
from  the  spine,  between  the  posterior  arch  of  the  atlas  and  the  corresponding  lamina  of 
the  axis,  in  the  same  line  as  the  posterior  branch  of  the  first  nerve,  immediately  below 
the  lower  border  of  the  obliquus  major,  and  is  reflected  upward  between  the  hairy  scalp 
on  the  one  hand,  and  the  occipitalis  muscle  and  epicranial  aponeurosis  on  the  other ;  it 
passes  horizontally  inward  between  the  obliquus  major  and  the  complexus,  perforates 
this  last  muscle  in  the  outer  side  of  its  digastric  portion  (the  biventer  cervicis),  then 
changes  its  direction,  and  turns  outward  between  the  complexus  and  the  trapezius, 
through  which  latter  it  passes  to  become  sub-cutaneous  and  accompany  the  occipital  ar- 
tery ;  it  is  here  called  the  great  occipital  nerve  (occipitalis  major,  a,  fig.  285).  Hither- 
to cylindrical,  this  nerve,  on  becoming  sub-cutaneous,  is  flattened,  and  increased  in 
width,  and  then,  passing  upward,  spreads  out  into  a  considerable  number  of  diverging 
branches,  internal,  middle,  and  external,  which  cover  the  occipital  region  with  their 
ramifications,  and  may  be  traced  even  to  the  parietal  region  :  the  internal  branches  are 
the  shortest,  and  are  successively  lost  in  the  skin  of  the  occipital  region. 

It  supplies  several  branches,  as  follows  :  Some  anastomotic  branches  to  the  first  and  third 
cervical  nerves. 

Opposite  the  lower  border  of  the  obliquus  major,  it  gives  off  a  considerable  muscular 
branch  (w,  fig.  300),  which  is  distributed  to  that  muscle,  to  the  complexus,  and  especial- 
ly to  the  splenius  (w,  fig.  298) ;  the  branches  to  the  splenius  are  of  great  size,  and  spread 
upon  its  deep  surface  into  diverging  twigs,  which  anastomose  both  with  each  other  and 
with  branches  derived  from  the  third  cervical  nerve. 

During  its  passage  between  the  obliquus  major  and  the  complexus,  and  between  the 
last-named  muscle  and  the  trapezius,  the  posterior  branch  of  the  second  cervical  nerve 
supplies  these  different  muscles  with  a  rather  large  number  of  nervous  twigs. 

Its  sub-cutaneous  portion  is  distributed  exclusively  to  the  hairy  scalp.  The  occipi- 
talis muscle,  upon  which  it  ramifies,  does  not  receive  any  branch  from  it :  as  we  shall 
elsewhere  show,  this  muscle  is  supplied  by  the  auricular  branch  of  the  facial  nerve. 
The  subdivisions  of  the  sub-cutaneous  portion  of  the  second  cervical  nerve  may  be  tra- 
ced into  the  hair  follicles,  and  several  of  its  external  branches  anastomose  with  the  mas- 
toid branch  of  the  anterior  cervical  plexus. 

The  Posterior  Branch  of  the  Third  Cervical  Nerve. 

The  posterior  branch  of  the  third  cervical  nerve,  smaller  than  that  of  the  second,  but 
much  larger  than  that  of  the  fourth  nerve,  and  partially  intended  for  the  occipital  region, 
emerges  between  the  transverse  process  of  the  atlas  and  that  of  the  third  cervical  ver- 
tebra, and,  consequently,  farther  outward  than  the  posterior  branches  of  the  first  and  sec- 
ond nerves ;  it  is  immediately  curved,  and  passes  transversely  inward  (t,  fig.  300)  be- 
tween the  complexus  and  the  semi-spinalis  colli.  Having  reached  the  inner  border  of 
the  complexus,  it  divides  into  two  cutaneous  branches  :  an  ascending  or  occipital,  which 
perforates  the  innermost  fibres  of  the  complexus,  passes  vertically  upward  upon  one  side 
of  the  median  line,  applied  to  the  under  surface  of  the  skin,  and  ramifies  upon  the  occip- 
ital region,  near  the  median  line,  and  to  the  inner  side  of  the  branch  from  the  second 
cervical  nerve  ;  and  a  horizontal  or  cervical  branch,  which  perforates  the  aponeurosis  of 
the  trapezius  between  the  complexus  and  the  posterior  cervical  ligament,  and  passes 
horizontally  outward  beneath  the  skin,  to  which  it  adheres,  and  in  the  substance  of 
which  it  terminates 

As  the  posterior  branch  of  the  third  cervical  nerve  emerges  from  the  posterior  inter- 
vertebral foramen,  it  gives  off  an  ascending  branch,  which  forms  an  anastomotic  arch 
with  the  descending  branch  of  the  second  nerve  :  the  succession  of  arches  formed  by  the 
anastomoses  of  the  first,  second,  and  third  nerves,  and  the  very  numerous  branches 
which  arise  from  their  convexities,  constitute  a  plexus,  which  may  be  called  the  posterior 
cervical  plexus :  it  is  situated  beneath  the  complexus,  near  its  external  attachments,  and 
it  supplies  both  that  muscle  and  the  splenius.  The  direct  anastomoses  between  the  pos- 
terior branches  of  the  three  superior  cervical  nerves  appear  to  me  to  be  sometimes  want- 
ing ;  but  then  the  branches  given  off  from  them  still  exist,  and  form  a  plexus  between 
the  splenius  and  the  complexus. 
The  Posterior  Branches  of  the  Fourth,  Fifth,  Sixth,  Seventh,  and  Eighth  Cervical  Nerves. 

The  posterior  branches  of  the  fourth,  fifth,  sixth,  seventh,  and  eighth  cervical  nerves  are  much 
smaller  than  the  preceding,  and  diminish  in  size  successively  from  the  fourth  to  the 

*  [Asch  saw  and  has  described  a  twig  {m,fig.  300)  proceeding  from  the  posterior  branch  of  the  first  cenri- 
«al  nerve  to  the  complexus  muscle  ;  Swan  and  Arnold    Iso  observed  it.] 


POSTERIOR   BRANCHES    OF   THE    DORSAL   NERVES.  TT6 

seventh.  Immediately  after  their  exit  from  the  posterior  inter- vertebral  foramina,  they 
are  reflected  inward  and  downward  in  the  following  manner :  the  fourth  and  fifth  (o')  in- 
cline downward  upon  the  semi-spinalis  colli,  between  it  and  the  complexus ;  the  sixth, 
seventh,  and  eighth  descend  ahnost  vertically  beneath  the  lowest  fasciculi  of  the  semi- 
spinalis  colli,  supply  that  muscle  and  the  raultifidus  spinae,  and  having  reached  the  side 
of  the  median  line,  perforate  the  aponeuroses  of  the  splenius  and  trapezius,  become  ap- 
plied to  the  skin,  and  ramify  in  it. 

The  Posterior  Branches  of  the  Dorsal,  Lumbar,  and  Sacral  JVerve. 

The  Posterior  Branches  of  the  Dorsal  Nerves. — These  are  intended  for  the  dorsal  region  of 
the  trunk,  and  resemble  each  other  closely  in  their  distribution,  presenting  only  a  few  dif- 
ferences connected  with  the  arrangement  of  the  particular  muscular  layers  of  each  region. 

The  posterior  branch  of  the  first  dorsal  nerve  has  the  same  muscular  and  cutaneous  re- 
lations as  the  corresponding  branches  of  the  lower  cervical  nerves ;  it  is  of  the  same 
size,  and  is  distributed  in  precisely  the  same  manner. 

The  posterior  branches  of  the  second,  third,  fourth,  fifth,  sixth,  seventh,  and  ei^A^A  dorsal 
nerves  are  destined  for  the  thorax,  properly  so  called,  and  present  the  greatest  uniformity 
in  their  size  and  distribution. 

They  all  emerge  from  the  posterior  inter-vertebral  foramina,  immediately  on  the  outer 
side  of  the  semi-spinalis  dorsi  and  multifidus  spinae,  and  divide  into  two  branches.  The 
external  or  muscular  branch  is  directed  towards  the  cellular  interval  between  the  sacro- 
lumbalis  and  longissiraus  dorsi,  and  subdivides  into  a  great  number  of  twigs,  which  are 
distributed  to  these  two  muscles  [and  to  the  levatores  costarum].  The  internal  or  mus- 
culo-cutaneous  branch  has  a  very  remarkable  course.  It  is  reflected  inward  over  the  semi- 
spinalis  dorsi,  embracing  the  outer  border  of  that  muscle,  and  supplying  it  with  nervous 
twigs ;  having  reached  the  side  of  the  spinous  process,  it  is  reflected  backward  along 
that  process,  perforates  the  spinal  attachments  of  the  latissimus  dorsi,  and  thus  gains 
the  under  surface  of  the  trapezius  ;  in  this  situation  it  is  reflected  outward  between  the 
latissimus  dorsi  and  the  trapezius,  perforates  the  latter  muscle  very  obliquely,  and  be- 
comes sub-cutaneous  ;  it  then  passes  horizontally  outward  in  the  fonn  of  a  small  nervous 
riband,  the  distinct  fibres  of  which  do  not  disunite  and  spread  out  in  the  substance  of 
the  skin  until  they  have  arrived  at  the  scapular  region.  The  cutaneous  branch,  which 
belongs  to  the  second  dorsal  nerve,  always  corresponds  to  the  triangular  surface  on  the 
spine  of  the  scapula,  over  which  the  aponeurosis  of  the  trapezius  glides. 

In  one  subject  which  I  examined,  the  musculo-cutaneous  divisions  of  the  posterior 
branches  of  the  third,  fourth,  and  fifth  dorsal  nerves  presented  two  ganglia  at  the  point 
where  they  bifurcated  into  their  muscular  and  cutaneous  branches ;  in  another,  the 
ganglia  were  situated  upon  the  cutaneous  branches  belonging  to  the  first  and  third  dor- 
sal nerves.  All  these  cutaneous  branches  are  horizontal,  parallel,  and  separated  from 
each  other  by  an  interval  corresponding  to  the  height  of  one  vertebra.  Such  of  the  pos- 
terior branches  of  the  dorsal  nerves  as  are  in  relation  with  the  trapezius  always  present 
the  preceding  arrangement.  But  the  branches  lower  down  than  that  muscle  are  dis- 
tributed in  the  following  manner : 

The  posterior  branches  of  the  ninth,  tenth,  eleventh,  and  twelfth  dorsal  nerves  are  distribu- 
ted in  precisely  the  same  way  as  the  posterior  branches  of  the  lumbar  nerves,  and,  like 
them,  are  intended  for  the  abdominal  parietes. 

There  is  no  longer  any  internal  or  musculo-cutaneous  branch,  the  external  branch 
representing  both  the  muscular  and  the  cutaneous  branch.* 

Immediately  after  emerging  from  the  inter-vertebral  foramina,  these  posterior  branches 
pass  very  obliquely  downward  and  outward,  gain  the  cellular  interval  between  the  sacro- 
iumbalis  and  the  longissimus  dorsi,  or,  rather,  pass  very  obliquely  through  the  common 
mass  formed  by  the  union  of  the  sacro-lumbalis  and  longissimus  dorsi,  and  almost  al- 
ways communicate  with  each  other  during  their  long  course  through  the  fleshy  fibres ; 
having  arrived  opposite  the  outer  border  of  the  latissimus  dorsi,  or  of  the  common  mass, 
these  branches,  diminished  fully  one  third  in  consequence  of  having  supplied  the  poste- 
rior spinal  muscles,  perforate  very  obliquely  the  aponeurotic  layer  formed  by  the  union 
of  the  aponeuroses  of  the  latissimus  dorsi  and  serratus  posticus  inferior,  with  those  from 
the  internal,  oblique,  and  transverse  muscles  of  the  abdomen,  and  become  sub-cutaneous ; 
they  then  divide  into  some  very  small  internal  cutaneous  filaments,  whicli  are  directed 
inward  upon  the  side  of  the  spinous  processes,  and  some  large  external  cutaneous  fila- 
ments, which  descend  to  terminate  in  the  skin  of  the  gluteal  region.  I  would  especially 
notice  several  large  nerves,  which,  either  joined  together,  or  only  in  contact,  descend 
vertically,  cross  perpendicularly  over  the  crest  of  the  ilium  in  front  of  the  outer  border 
of  the  common  mass  of  the  lumbar  muscles,  and  become  applied  to  the  integuments  of  the 
gluteal  region,  upon  which  they  may  be  traced  as  far  as  the  great  trochanter. 

*  iThe  internal  branches  of  the  four  lower  nerve.s  are  not  absent,  but  are  much  reduced  in  size,  do  not 
reach  the  surface,  and  are  distributed  principally  to  the  multifidus  spinae:  the  external  branches  give  the 
cutaneous  twigs.  (Demonstrations  of  Anatomij,  by  G.  V.  Ellis,  of  whose  labours  in  reference  to  the  anatomy 
of  the  nerves,  free  use  has  been  made  in  this  and  many  of  the  succeeding  notes.)] 


776  NEUROLOGT. 

The  Posterior  Branches  of  the  Lumbar  Nerves. — These  resemble  in  their  distribution  the 
corresponding  branches  of  the  four  lower  dorsal  nerves  ;  they  gradually  diminish  in  size 
from  above  downward ;  the  fifth  is  extremely  small,  and  is  entirely  expended  in  the 
common  mass  of  the  lumbar  muscles. 

The  Posterior  Branches  of  the  Sacral  Nerves. — These  branches  emerge  from  the  poste- 
rior sacral  inter-vertebral  foramina.  It  is  difficult  to  dissect  them,  because  they  are 
extremely  small,  and  penetrate  immediately  into  the  muscular  mass  which  occupies  the 
sacral  groove  ;  they  moreover  decrease  in  size  from  above  downward,  and  are  uniformly 
arranged  in  the  following  manner  :  immediately  after  their  exit  from  the  posterior  inter- 
vertebral foramina,  they  form  anastomotic  arches  with  each  other,  from  which  muscular 
and  cutaneous  filaments  are  given  off.  The  former  are  distributed  to  the  common  mass 
and  the  glutaeus  maxiraus,  and  the  latter  are  intended  for  the  skin  of  the  sacral  region.* 

The  Anterior  Branches  of  the  Spinal  Nerves. 

The  anterior  branches  of  the  spinal  nerves,  which  are  generally  larger  than  the  posterior, 
are  the  true  continuations  of  these  nerves,  and  supply  the  lateral  and  anterior  parts  of 
the  trunk,  and  also  the  upper  and  lower  extremities. 

Such  of  these  branches  as  are  intended  for  the  trunk  of  the  body  have  an  extremely 
uniform  and  very  simple  mode  of  distribution ;  to  this  class  belong  the  intercostal 
nerves :  those,  on  the  other  hand,  which  are  intended  for  the  upper  and  lower  extremi- 
ties, present,  in  their  distribution,  a  degree  of  complexity  which  depends  on  that  of  the 
parts  which  they  supply.  To  this  class  belong  the  anterior  cervical,  anterior  lumbar,  and 
anterior  sacral  branches. 

The  three  last-named  sets  of  branches,  almost  immediately  after  their  exit  from  the 
spinal  canal,  communicate  with  each  other,  so  as  to  form  interlacements  or  plexuses, 
from  which  are  given  off  the  nerves,  that  ultimately  ramify  in  all  parts  of  the  body. 

There  are  four  great  plexuses  :  two  for  the  region  of  the  neck  and  the  upper  extrem- 
ity, viz.,  the  cervical  plexus  (x,fig.  268)  and  the  brachial  plexus  (h),  which  might  be  re- 
garded as  a  single  plexus,  the  cervico-brachial ;  and  two  for  the  lumbar  region  and  the  low- 
er extremity,  viz.,  the  lumbar  (/)  and  the  sacral  or  crural  plexus  (s),  which  also  might  be 
regarded  as  one,  the  lumbosacral  plexus. 

After  these  preliminary  observations,  I  shall  now  describe,  in  succession,  the  anterior 
branches  of  the  cervical,  dorsal,  lumbar,  and  sacral  nerves. 


THE  ANTERIOR  BRANCHES  OF  THE  CERVICAL  NERVES. 

Dissection. — Anterior  Branch  of  the  First,  Second,  Third,  and  Fourth  Cervical  Nerves. — 
The  Cervical  Plexus  —  Its  Anterior  Branch,  the  Superficial  Cervical  —  Its  Ascending 
Branches,  the  Great  Auricular  and  the  External  or  Lesser  Occipital — Its  Superficial  De- 
scending Branches,  the  Supra-clavicular — Its  Deep  Descending  Branches,  the  Nerve  to  the 
Descendins  Noni  and  the  Phrenic — Its  Deep  Posterior  Branches. — The  Anterior  Branches 
of  the  Fifth,  Sixth,  Seventh,  and  Eighth  Cervical,  and  First  Dorsal  Nerves. — The  Brach- 
ial Plexus. — Its  Collateral  Branches  above  the  Clavicle — Its  Muscular  Branches,  Poste- 
rior Thoracic,  Supra-scapular,  opposite  to  the  Clavicle,  the  Thoracic,  below  the  Clavicle,  the 
Circumflex — Its  Terminal  Branches,  the  Internal  Cutaneous  and  its  Accessory,  the  Mus- 
culo-cutaneous,  the  Median,  the  Ulnar,  the  Musculo-spiral  or  Radial. — Summary  of  the 
Distribution  of  the  Branches  of  the  Brachial  Plexus. 

Dissection. — It  is  convenient  to  dissect  the  sub-cutaneous  branches  which  emerge 
from  the  cervical  plexus  before  examining  the  anterior  branches  of  the  cervical  nerves  : 
one  side  of  the  neck  may  be  reserved  for  the  superficial,  and  the  other  for  the  deep 
branches. 

The  Anterior  Branches  of  the  First,  Second,  Third,  and  Fourth  Cervical  Nerves. 

The  Anterior  Branch  of  the  First  Cervical  Nerve. — This  branch  {u.  Jig.  300)  emerges 
from  between  the  occipital  bone  and  the  posterior  arch  of  the  atlas  in  the  groove  for  the 
vertebral  artery,  and  beneath  that  vessel ;  opposite  the  foramen  in  the  transverse  pro- 
cess of  the  atlas,  it  leaves  the  artery,  passes  in  front  of  the  base  of  that  process,  is  re- 
flected downward,  and  descends  to  form  an  anastomotic  arch  with  the  anterior  branch 
of  the  second  nerve.  As  all  the  branches  belonging  to  the  first  nerve  come  off  from  this 
anastomotic  arch,  they  will  be  described  with  the  second  nerve. 

The  Anterior  Branch  of  the  Second  Cervical  Nerve. — This  is  much  smaller  than  the  pos- 
terior branch  of  the  same  nerve  ;  it  passes  horizontally  forward  between  the  transverse 
processes  of  the  atlas  and  axis,  is  reflected  in  front  of  the  axis,  and  divides  into  an  as- 
cending and  a  descending  branch. 

*  Among  the  cutaneous  filaments  which  proceed  from  the  arch  formed  by  the  jposterior  branches  of  the  first 
and  second  sacral  nerves,  there  i*  one  wliich  passes  below  the  posterior  and  inferior  spinous  process  of  the 
ilium,  is  directed  vertically  downward  between  the  glutieus  m:i.\iraQs  and  the  lesser  sacro-sciatic  ligament, 
oerforates  the  gluUeus  muxiiuus,  and  is  then  reflected  outward  in  noutact  with  the  skin. 


THE  CERVICAL  PLEXUS.  777 

The  ascending  branch  curves  upward  in  front  of  the  transverse  process  of  the  atlas,  and 
j^j^astomoses  in  an  arch  with  the  anterior  branch  of  the  first  nerve. 
.,  The  descending  branch  {z,  fig.  298)  subdivides  into  two  others  of  almost  equal  size  :  the 
.'one  internal  (see  also  fig.  300),  which  constitutes  the  internal  descending  cervical  nerve 
(before  s,  fig.  298) ;  the  other  external  (behind  s),  which  anastomoses  with  the  third  nerve 
^.^above  s),  to  form  the  superficial  cervical  nerve  {k)  and  the  great  auricular  nerve  (q). 

Several  large  filaments  for  the  rectus  capitis  anticus  major  are  given  off  from  the  angle 
.of  bifurcation  of  the  ascending  and  descending  branches. 

**  The  anastomotic  arch  formed  by  the  anterior  branches  of  the  first  and  second  cervi- 
cal nerves  gives  off  three  or  four  very  large  grayish  branches  and  several  small  white 
filaments,  which  go  to  the  superior  cervical  ganglion  of  the  sympathetic  ;  above  these  it 
gives  a  short  gray  filament,  which  almost  immediately  swells  into  a  ganglion,  from  which 
a  long,  slender,  descending  filament  proceeds  to  join  the  internal  descending  nerve ;  lastly, 
it  furnishes  two  ascending  filaments,  the  lower  one  of  which  joins  the  pneumogastric 
nerve,  and  the  upper  one  the  hypoglossal  or  ninth  nerve. 

The  Anterior  Branch  of  the  Third  Cervical  Nerve. — This  (above  s,  fig.  298)  is  twice  as 
*  large  as  the  preceding ;  it  at  first  passes  forward  to  emerge  from  the  inter-transverse 
space,  then  downward  and  outward,  and  having  gained  the  under  surface  of  the  stemo- 
mastoid  muscle,  it  expands  into  a  great  number  of  branches,  which  constitute  the  cervi- 
cal plexus  properly  so  called,  and  may  be  divided  into  a  superior  and  an  inferior  portion. 

The  superior  division  passes  outward  and  backward  beneath  the  sterno-mastoid  mus- 
'■■«de,  and  bifurcates  upon  its  posterior  borders.  One  of  the  branches  of  the  bifurcation  as- 
cends, and  is  called  the  mastoid  nerve  (y) ;  the  other,  which  is  reflected  over  the  posterior 
border  of  the  muscle,  anastomoses  by  one  or  two  filaments  with  the  anterior  branch  of 
the  second  cervical  nerve,  and  subdivides  into  the  superficial  cervical  nerve  {k)  and  the 
auricular  nerve  (q) :  both  of  the  branches  of  the  bifurcation  anastomose  with  the  second 
cervical  nerve.  This  superior  division,  moreover,  gives  off  a  small  nerve,  which  as- 
cends between  the  auricular  and  mastoid  nerves  ;  also  a  communicating  branch  to  the 
superior  cervical  ganglion ;  and,  lastly,  a  series  of  branches  («),  which  anastomose  with 
the  spinal  accessory  nerve  of  Willis  (<),  some  immediately,  and  others  while  v/ithin  the 
substance  of  the  sterno-mastoid  muscle.  This  superior  division  of  the  third  nerve  some- 
times joins  the  lowest  branch  of  the  second  nerve. 

The  inferior  or  descending  portion  passes  vertically  downward  in  front  of  the  scalenus 
anticus,  gives  off  a  long  slender  filament  to  the  internal  desccndi7ig  cervical  nerve,  and  ter- 
minates partly  by  anastomosing  with  the  fourth  cervical  nerve  (below  s),  and  partly  by 
becoming  continuous  with  the  clavicular  nerves  (w). 

A  considerable  branch  which  enters  the  levator  anguli  scapulas  may  be  regarded  as  be- 
longing to  this  inferior  portion.  This  branch  for  the  angularis  sometimes  arises  at  the 
point  of  bifurcation  of  the  anterior  branch  of  the  third  nerve. 

The  Anterior  Branch  of  the  Fourth  Cervical  Nerve. — This  branch  (below  s)  is  of  the 
same  size  as  the  preceding  ;  it  gives  off  the  phrenic  nerve  (J),  which  sometimes  arises  in 
the  inter-transverse  space  ;  it  then  passes  downward  and  outward  in  contact  with  the 
scalenus  anticus  for  about  ten  lines,  and  divides  into  two  terminal  branches,  the  one  in- 
ternal, the  other  external,  which  soon  subdivide  and  cover  the  supra-clavicular  triangle 
with  their  diverging  ramifications :  these  branches  constitute  the  supra-clavicular  and 
acromial  nerves  (m).  Just  opposite  its  division  the  anterior  branch  of  the  fourth  cervi- 
cal ner\'e  receives  a  branch  from  the  third,  which  appears  to  be  shared  between  its  two 
terminal  divisions. 

The  fourth  cervical  generally  sends  off  a  small  communicating  branch  to  the  fifth  cer- 
vical nerve. 

The  Cervical  Plexus. 

The  term  cervical  plexus  is  applied  to  the  series  of  anastomoses  (z  s)  formed  by  the  an 
terior  branches  of  the  first,  second,  third,  and  fourth  cervical  nerves. 

Some  anatomists  call  it  the  deep  cervical  plexus,  in  contradistinction  to  the  superficial 
branches  given  off  from  it,  which,  according  to  this  view,  constitute  the  superficial  cervi 
cal  plexus. 

This  plexus,  which  occupies  the  anterior  and  lateral  aspect  of  the  four  superior  cer- 
vical vertebrae,  is  situated  beneath  the  posterior  border  of  the  sterno-cleido-mastoid  mus- 
cle, to  the  outer  side  of  the  internal  jugular  vein,  between  the  rectus  capitis  anticus  ma- 
jor and  the  cervical  attachments  of  the  splenius  and  levator  anguli  scapulae  :  it  is  con- 
cealed by  a  considerable  quantity  of  fat,  and  by  a  great  number  of  lymphatic  glands  :  it 
is  also  covered  by  an  aponeurotic  lamina,  which  adheres  to  it  intimately,  and  is  prolong- 
ed upon  the  nerves  which  emanate  from  it. 

After  the  example  of  Bichat,  this  plexus  may  be  regarded  as  a  centre  in  which  the 
anterior  branches  of  the  four  superior  cervical  nerves  terminate,  and  from  which  a  great 
number  of  branches  proceed.  This  plexus  is  by  no  means  inextricable  ;  it  is  always 
easy  to  determine  the  origin  of  the  branches  which  come  from  it. 

These  branches  consist  of  one  anterior  branch,  the  superficial  cervical  {k) ;  of  ascending 

5  F 


778 


NEUROLOGY. 


branches,  viz.,  the  great  mastoid  (y),  the  small  mastoid,  and  the  great  auricular  (q) ;  and 
of  descending  branches,  subdivided  into  the  deep  and  the  superficial ;  the  deep  ones 
consisting  of  the  itUerjial  descending  branch  (before  s),  the  •phrenic  nerve  (/),  and  the  branch- 
es for  the  trapezius,  levator  anguli  scapula,  and  rhomboideus ;  the  superficial  descending 
branches  are  the  supra-clavicular  and  the  acromial  (m). 

According  to  their  distribution,  they  may  also  be  divided  into  muscular  and  cutaneous 
branches  ;  the  muscular  consist  of  the  internal  descending,  the  phrenic,  the  branches  for 
the  trapezius,  the  levator  anguli,  and  the  rhomboideus  ;  all  the  others  are  cutaneous, 
and  are  flattened  like  ribands. 

The  Ajiterior  Branch. 

The  Superficial  Cervical  JVerve. 

The  superficial  cervical  nerve  (superficialis  colli,  s,  fig.  285),  which  is  often  double, 
Pig.  285.  in  consequence  of  dividing  earlier  than  usual,  is  des- 

tined exclusively  for  the  skin  of  the  neck  and  lower 
part  of  the  face  (sous-mentonniere,  Chauss.),  and  is 
formed  by  the  anastomoses  of  the  second  and  third 
cervical  nerves  ;  it  emerges  from  the  plexus  opposite 
the  middle  of  the  neck,  beneath  the  posterior  border 
of  the  sterno-mastoid,  around  which  it  turns  in  the 
form  of  a  loop,  and  then  passes  horizontally  forward 
between  that  muscle  and  the  platysma,  runs  at  right 
angles  beneath  the  external  jugular  vein,  and  divides 
into  two  branches — one  ascending  and  larger,  the  oth- 
er descending ;  these  two  branches  often  form  two 
distinct  nerves. 

The  descendijig  branch  passes  downward  and  in- 
ward between  the  sterno-mastoid  and  the  platysma,  is 
reflected  upward  so  as  to  form  a  loop,  having  its  con- 
cavity turned  upward,  perforates  the  platysma,  and 
then  lies  in  contact  with  the  skin,  beneath  which  it 
may  be  traced  as  far  as  opposite  the  os  hyoides. 
One  of  its  twigs,  which  appears  to  me  to  be  constant,  having  reached  the  side  of  the 
median  line,  is  reflected  upward  in  front  of  the  anterior  jugular  vein,  ascends  vertical- 
ly, and  may  be  traced  into  the  skin  of  the  supra-hyoid  region. 

The  ascending  branch,  which  sometimes  arises  by  a  common  trunk  with  the  auricular 
nerve,  immediately  divides  into  four  or  five  very  slender  and  slightly  waving  filaments, 
which,  situated  at  first  between  the  sterno-mastoid  and  the  platysma,  generally  perfo- 
rate the  last-named  muscle,  to  become  sub-cutaneous  ;  two  of  these  diverging  filaments, 
which  remain  subjacent  to  the  platysma,  are  very  slender,  and  run  along  the  external 
jugular  vein,  one  in  front  of  and  the  other  behind  that  vessel. 

Ail  the  other  filaments  pass  upward  and  inward  in  contact  with  the  skin,  and  subdi- 
vide into  a  great  number  of  filaments,  which  may  be  traced  as  far  as  the  skin  of  the  chin 
and  lower  part  of  the  cheek ;  I  have  seen  two  of  these  filaments  anastomose  with  the 
facial  nerve.  It  is  important  to  observe,  that  the  cervical  filaments  of  the  facial  nerve 
occupy  a  deeper  plane  than  those  of  the  superficial  cervical  nerve,  and  are  separated 
from  these  latter  in  front  by  the  platysma. 

The  Ascending  Branches. 

The  Auricular  J^erve. 

The  auricular  nerve  (auricularis  magnus,  d,  fig.  285),  the  ascending  anterior  branch  of 
the  cervical  plexus,  arises  from  the  second  and  third  cervical  nerves  by  a  trunk  which 
is  common  to  it  and  to  the  superficial  cervical ;  it  emanates  from  the  plexus  immediate- 
ly above  the  last-named  nerve,  hke  which  it  embraces  the  posterior  border  of  the  sterno- 
mastoid  so  as  to  form  a  loop  with  the  convexity  turned  backward,  and  then  passes  up- 
ward and  a  little  forward  between  the  platysma  and  the  sterno-mastoid,  and  reaches  the 
anterior  border  of  that  muscle  opposite  the  angle  of  the  lower  jaw.  In  this  situation  it 
gives  off"  several  facial  or  parotid  filaments,  and  terminates  by  dividing  into  a  superficial 
and  a  deep  branch. 

The  facial  or  parotid  branches  are  very  slender ;  some  of  them  pass  between  the  parot- 
id and  the  skin,  with  which  they  are  in  contact ;  the  others  pass  through  the  parotid 
gland  from  behind  forward,  and  from  below  upward,  to  be  distributed  to  the  skin  of  the 
cheek  ;  I  have  traced  them  as  far  as  the  skin  which  covers  the  malar  bone  ;  it  has  not 
been  shown  that  some  of  them  terminate  in  the  substance  of  the  parotid,  as  has  been 
stated.* 

The  superficial  auricular  branch  ascends  vertically,  in  the  substance  of  the  very  dense 

*  I  have  seen  two  of  these  parotid  filaments  terminate  in  a  small  abnormal  ganglioii,  from  which  other  fil 
aments  were  given  off  and  distributed  in  the  manner  above  described 


THE    SUPRA-CLAVICULAR    NERVES.  779 

fibrous  tissue  which  connects  the  parotid  to  the  skin  ;  it  gains  the  lower  part  of  the 
concha  opposite  to  the  anti-tragus,  and  then  divides  into  several  filaments,  the  distribu- 
tion of  which  is  remarkable  :  the  largest  passes  above  the  lobule  in  the  fissure  between 
the  concha  and  the  caudal  extremity  of  the  helix,  and  is  distributed  to  the  skin  on  the 
concave  surface  of  the  auricle,  and  especially  to  the  skin  of  the  concha  ;  another  fila- 
ment turns  round  the  margin  of  the  auricle,  and  gains  the  groove  of  the  helix,  which  it 
follows  even  to  its  upper  part. 

The  deep  auricular  branch,  which  may  be  called  the  antenor  mastoid,  perforates  the 
substance  of  the  parotid  gland,  and  gains  the  front  of  the  mastoid  process ;  here  it 
crosses  at  an  acute  angle  over  the  auricular  branch  of  the  facial  nerve,  which  is  more  deep- 
ly seated,  and  with  which  it  anastomoses  by  a  rather  large  branch  ;  it  then  passes  be- 
hind the  posterior  auricular  muscle,  and  divides  into  two  secondary  branches  :  a  poste- 
rior, which  passes  upward  and  backward,  and  may  be  traced  as  far  as  the  outer  border 
of  the  occipitalis  muscle,  where  it  anastomoses  with  a  very  delicate  filament  of  the  ex- 
ternal occipital  nerve  ;  and  an  anterior,  which  runs  upon  the  upper  part  of  the  cranial 
surface  of  the  auricle.  The  superior  filaments  are  reflected  over  the  upper  margin  of 
the  auricle,  and  are  distributed  to  the  skin  which  covers  its  external  or  concave  surface. 
From  what  has  been  just  stated,  it  follows  that  the  auricularis  magnus  gives  off  no 

.  muscular  filament.     The  posterior  auricular  and  occipitalis  muscles  are  supplied  entire- 

"  ly  from  the  auricular  branch  (c)  of  the  facial  nerve. 

The  Mastoid  or  External  Occipital  Kerve. 
The  mastoid  or  external  occipital  nerve  (occipitalis  minor,  b),  the  posterior  ascending 
branch  of  the  cervical  plexus,  rises  from  the  second  cervical  nerve  ;  it  comes  off  from 
the  plexus  above  the  preceding  nerve,  describes  a  loop  with  the  convexity  turned  up- 
ward upon  the  posterior  border  of  the  sterno-mastoid,  ascends  almost  vertically,  parallel 
to  the  great  occipital  nerve  and  to  the  posterior  border  of  the  sterno-mastoid,  crosses 
the  posterior  occipital  attachments  of  that  muscle,  continues  to  ascend  upon  the  occipi- 
fe'tal  region,  and  then  upon  the  parietal  region,  and  may  be  traced  as  far  as  opposite  the 
t  anterior  border  of  the  parietal  bone.     During  this  course  it  is  situated  between  the  sple- 
jiius  and  occipitalis  muscles  and  epicranial  aponeurosis  on  the  one  hand,  and  the  skin  on 
"the  other. 

This  nerve  gives  off  in  the  occipital  region  some  external  branches,  which  are  distrib- 
uted to  the  skin,  and  anastomose  with  a  filament  of  the  auricular  nerve,  but  none  of  them 
pass  to  the  auricle.  The  term  occipito-auricular  (Chauss.)  is,  therefore,  not  applicable  to 
it ;  it  should  rather  be  called  the  external  occipital  (occipitalis  minor,  b),*  to  distinguish 
.  it  from  the  internal  occipital  (occipitalis  major,  a),  given  off  by  the  posterior  branch  of 
the  second  cervical  nerve. 

It  also  supplies  some  internal  branches,  which  anastomose  several  times  with  the  in- 
ternal occipital  nerve,  and  are  distributed  to  the  skin. 

It  gives  no  filament  to  the  occipitalis  muscle,  nor  does  it  anastomose  with  the  facial 
nerve.     The  mastoid  or  external  occipital  nerve  is  essentially  a  cutaneous  nerve. 

We  sometimes  find  a  small  supplementary  branch  between  the  great  auricular  and 
.external  occipital  nerves,  which  runs  parallel  to  them,  and  may  be  called  the  small  mas- 
..  jtoid  nerve  (c). 

The  Superficial  Descending  Branches. 
The  Supra-clavicular  JVerves. 

The  Supra-clavicular  Nerves  {e,fig.  285  ;  u,fig.  298). — The  terminating  branches  of  the 
cervical  plexus  are  two  in  number :  one  internal,  or  the  supra-clavicular  nerve,  properly 
so  called  ;  the  other  external,  or  the  acromial  nerve ;  they  come  off  from  the  plexus  at 
the  posterior  border  of  the  sterno  mastoid,  descend  perpendicularly  towards  the  clavicle, 
and  divide  into  several  branches,  which  again  subdivide  before  reaching  that  bone,  so 
that  they  cover  the  supra-clavicular  triangle  with  their  diverging  filaments.  All  these 
branches  cross  over  the  clavicle  at  almost  regular  intervals,  and  are  lost  upon  the  upper 
and  anterior  part  of  the  thorax. 

The  innermost  or  sternal  branches  cross  very  obliquely  over  the  external  jugular  vein, 
then  over  the  clavicular  and  sternal  attachments  of  the  sterno-mastoid,  and  ramify  in 
the  skin,  where  they  may  be  traced  as  far  as  the  median  line. 

The  external  or  acromial  branches  pass  obliquely  over  the  external  surface  of  the  tra- 
pezius, cross  the  outer  end  of  the  clavicle,  and  are  distributed  to  the  skin  over  the  acro- 
mion and  the  spine  of  the  scapula.  I  have  followed  some  filaments  over  the  top  of  the 
shoulder  as  far  as  the  lower  borders  of  the  pectoralis  major. 

The  intermediate  or  clavicular  branches  cross  the  clavicle  at  right  angles,  are  in  con- 
tact with  the  skin  upon  the  upper  part  of  the  thorax,  and  maybe  traced  to  within  a  short 
distance  of  the  nipple,  t 

*  The  name  mastoid  branch  is  bad,  for  this  branch  has  no  relation  with  the  mastoid  process, 
t  Not  unfrequcntly  the  supra-clavicular  nerve  passes  through  a  foramen  in  the  clavicle,  at  the  junction  of 
the  external  third  with  the  internal  two  thirds  of  that  bone  ;  sometimes,  instead  of  a  bony  canal,  there  is  A 


t80  NEUROLOGY. 

All  these  branches  lie  at  first  beneath  the  platysma,  and  then  become  sub- cutaneous. 
A  layer  of  fascia  and  the  omo-hyoid  muscle  are  interposed  between  them  and  the  scaleni 
muscles  and  brachial  plexus.  Some  loose  cellular  tissue  separates  them  from  the  clav- 
icle, upon  which  they  glide  with  the  greatest  freedom. 

The  Deep  Descending  Branches. 
The  Internal  Descending  Cervical  J^erve. 

The  internal  descending  cervical  nerve  (before  s,  fig.  298),  which  is  destined  exclusively 
for  the  muscles  of  the  sub-hyoid  region,  may  be  considered  as  the  inferior  branch  of  the 
bifurcation  of  the  second  cervical  nerve,  although  the  first  and  third  nerves  each  give  to 
it  a  small  re-enforcing  filament. 

It  passes  vertically  downward,  on  the  outer  side  of  the  internal  jugular  vein,  along 
which  it  runs,  is  joined  on  its  inner  side  by  a  filament  from  the  first  cervical  nerve,  and 
having  reached  a  little  below  the  middle  of  the  neck,  is  reflected  inward  in  front  of  the 
internal  jugular  vein,  and  forms  an  anastomotic  loop,  which  is  sometimes  plexiform,  with 
the  descending  branch  (descendens  noni,  h)  of  the  hypoglossal  nerve  ;  this  is  a  remark- 
able anastomosis,  and  presents  many  varieties  in  its  arrangement.  The  convexity  of 
this  loop  is  turned  downward,  and  from  it  arises  a  branch,  which  sometimes  scarcely  ex- 
ceeds in  size  either  of  the  formative  branches  of  the  loop,  and  which  expands  into  sev- 
eral filaments  {g).  One  of  these  ascends  and  supplies  the  superior  attachments  of  the 
sterno-hyoid  and  omo-hyoid  ;  a  transverse  filament  proceeds  to  the  bodies  of  the  sterno- 
hyoid and  sterno-thyroid  muscles.  Several  filaments  can  be  traced  as  far  as  the  lower 
part  of  the  latter  muscle,  that  is  to  say,  down  to  opposite  the  second  rib.  The  inferior 
fleshy  belly  of  the  omo-hyoid  is  supplied  by  some  twigs  derived  from  the  filaments  which 
enter  its  superior  belly. 

The  Phretdc  or  Diaphragmatic  Jferve. 

The  phrenic  nerve  {I,  figs.  298,  302)  is  a  branch  derived  from  the  fourth  cervical  nerve, 
sometimes  re-enforced  by  a  very  small  filament  from  the  third  nerve,  and  almost  al- 
ways by  a  larger  branch  from  the  fifth.*  Not  unfrequently  one  of  the  formative  branch- 
es of  the  loop  of  the  hypoglossal  nerve  just  described  joins  the  phrenic  nerve.  The  right 
and  left  phrenics  are  rarely  of  the  same  size. 

After  its  origin,  the  phrenic  nerve  descends  vertically  in  front  of  the  inner  border  of 
the  scalenus  anticus,  with  which  it  is  held  in  contact  by  a  fascia.  It  is  round  at  first, 
but  becomes  flattened  as  it  passes  between  the  sub-clavian  vein  and  artery  (I  have  seen 
it  pass  in  front  of  the  vein),  and  is  then  inclined  slightly  inward,  to  enter  the  superior 
orifice  of  the  thorax.  In  the  thorax  (Z,  fig.  302)  it  continues  its  vertical  direction,  runs 
along  the  brachio-cephalic  vein  on  the  left  side,  and  along  the  vena  cava  superior  on  the 
right  side,  is  then  applied  against  the  pericardium,  to  which  it  is  bound  down  by  the 
pleura,  and,  having  reached  the  diaphragm,  ramifies  in  that  muscle.  It  is  accompanied 
by  the  superior  phrenic  artery,  which  is  a  branch  of  the  internal  mammary,  and  the  su- 
perior phrenic  vein. 

The  phrenic  nerve  gives  off  no  branches  in  the  thorax :  at  a  short  distance  from  its 
origin,  it  anastomoses  with  the  great  sympathetic  by  a  transverse  branch :  at  the  lower 
part  of  the  neck,  it  sometimes  gives  off  a  filament,  which  forms  an  anastomotic  arch  with 
a  branch  derived  from  the  fifth  and  sixth  cervical  nerves.  I  have  never  seen  it  com- 
municate with  the  inferior  cervical  ganglion. 

The  distribution  of  this  nerve  in  the  diaphragm  is  curious.  Some  of  its  expanded,  di- 
verging, and  generally  very  long  filaments,  run  between  the  pleura  and  the  diaphragm, 
and  enter  the  muscle  from  its  upper  surface  ;  others  pass  through  the  diaphragm,  run 
between  it  and  the  peritoneum,  and  enter  the  fleshy  fibres  from  below  ;  they  may  be 
traced  as  far  as  the  costal  attachments  of  the  muscle.  The  right  phrenic  nerve  termi- 
nates by  a  transverse  branch  which  passes  behind  the  vena  cava,  and  anastomoses  with 
certain  transverse  branches  of  the  left  phrenic,  before  it  enters  the  pillars  of  the  dia- 
phragm, in  which  it  terminates.  I  have  never  seen  any  filament  of  the  phrenic  nerv6 
pass  either  to  the  oesophagus  or  to  the  solar  plexus. 

The  Posterior  Deep  Cervical  Branches. 
These  are,  an  anastomotic  branch  iv,fig.  298)  from  the  cervical  plexus  to  the  spinal  ac- 
cessory nerve  of  Willis  (t) ;  it  is  of  considerable  size  ;  it  comes  off  from  the  second  nerve 
at  the  same  point  as  the  external  occipital  nerve,  and  an2istomoses  at  an  acute  angle 

tendinous  arch  upon  the  posterior  border  of  the  bone.  In  this  case  the  clavicular  branches  are  not  scattered, 
but  closely  aggregated  together  :  the  internal  branches  then  pass  horizontally  inward  between  the  clavicle  and 
the  skin  as  far  as  the  sternum  ;  and  I  have  even  seen  a  small  twig  enter  the  attachments  of  the  pectoralis  ma 
jor.  The  external  branches  proceed  horizontally  outward  upon  the  anterior  border  of  the  clavicle  as  far  as  the 
acromion. 

*  The  communication  between  the  phrenic  nerve  and  the  fifth  cervical  nerve  occurs  in  many  different  modeg. 
Sometimes  the  phrenic  supplies  the  communicating  filament,  instead  of  receiving  it ;  most  commonly  the 
phrenic  branch  of  the  fifth  arises  by  a  common  trunk  with  the  nerve  for  the  sub-clavius  muscle,  crosses  in 
front  of  the  subclavian  vein,  between  it  and  the  cartilage  of  the  first  rib,  with  which  it  is  in  contact,  and 
•Mscs  behind  the  internal  mammary  artery,  to  join  the  phrenic  nerve  at  a  very  acute  angle. 


THE  BRACHIAL  PLEXUS.  781 

with  the  spinal  accessory,  between  the  cervical  fasciculi  of  the  splenius  and  the  sterno- 
mastoid. 

Also,  a  ira.ncM.jor  the  trapezius,  which  arises  from  the  third  nerve,  passes  obliquely 
downward  and  backward  to  the  deep  surface  of  the  muscle,  and  anastomoses  with  the 
spinal  accessory  of  Willis,  which  it  re-enforces,  and  with  which  it  may  be  traced  as  far 
as  the  lower  angle  of  the  muscle. 

Lastly,  the  branches  for  the  levator  anguli  scapulce  and  the  rhomboideus ;  these  are  rath- 
er small  branches,  which  arise  from  the  back  part  of  the  third  and  fourth  cervical  nerves, 
as  they  emerge  from  between  the  transverse  processes  of  the  vertebrae,  pass  obliquely 
downward  and  backward,  turn  round  the  scalenus  posticus  in  contact  with  it,  and  are 
distributed  to  the  levator  anguli  scapulsD  and  the  upper  part  of  the  rhomboideus.  The 
same  branches  appear  to  supply  both  muscles. 

The  Anterior  Branches  of  the  Fifth,  Sixth,  Seventh,  and  Eighth  Cervical 
AND  First  Dorsal  Nerves. 

These  branches  are  remarkable  for  their  size,  in  which  respect  they  surpass  the  pre- 
ceding, and  are  almost  all  equal.  On  emerging  from  the  inter-vertebral  foramina,  they 
come  into  relation  with  the  two  scaleni  muscles,  which  are  separated  from  each  other, 
and  sometimes  are  perforated  by  them ;  they  give  off  some  very  slender  filaments  to 
these  muscles,  and,  converging,  anastomose  together  so  as  to  form  the  brachial  plexus, 
from  which  all  the  nerves  of  the  upper  extremity  are  derived. 

The  Brachial  Plexus. 

The  brachial  plexus  {h,jig.  268)  extends  obliquely  from  the  lateral  and  inferior  part  ol 
the  neck  to  the  cavity  of  the  axilla,  or,  rather,  to  the  inner  side  of  the  head  of  the  hume- 
rus, where  it  terminates  by  dividing  into  the  nerves  of  the  upper  extremity ;  it  is  formed 
in  the  following  manner : 

The  fifth  and  sixth  cervical  nerves  (5,  6,  fig.  286)  unite  at  a  short  distance  from  the 
scaleni,  and  the  cord  thus  formed  passes  very  obliquely  downward  and  outward,  and 
then  bifurcates. 

Again,  the  eighth  cervical  (8)  and  the  first  dorsal  (1)  nerves  unite  immediately  after 
converging  from  the  scaleni,  and  sometimes  even  between  those  muscles ;  and  the  com- 
mon cord  passes  almost  horizontally  outward,  and  bifurcates  near  the  head  of  the  humerus. 

Between  these  two  anastomotic  cords  is  the  seventh  cervical  nerve  (7),  which  pur- 
sues a  much  longer  course  than  the  others,  and  bifurcates  on  a  level  with  the  clavicle  ; 
the  upper  branch  of  its  bifurcation  joins  the  lower  branch  of  the  bifurcation  of  the  first- 
named  cord,  and  its  lower  branch  unites  with  the  upper  branch  of  the  second-named  cord. 

From  these  several  bifurcations  and  subsequent  anastomoses,  all  of  which  take  place 
at  very  acute  angles,  results  the  interlacement  known  as  the  brachial  plexus. 

The  brachial  plexus  is  broad  at  its  upper  part,  contracted  in  the  middle,  and  broad 
again  at  its  lower  part,  on  account  of  the  divergence  of  its  terminating  branches ;  it  com- 
municates with  the  cervical  plexus  by  a  considerable  branch,  which  it  receives  from  the 
fourth  cervical  nerve,  and  also  by  the  filament  which  it  gives  to  the  phrenic  nerve ;  it  is 
not  so  complicated  but  that  the  origins  of  the  branches  which  emanate  from  it  may  be 
traced ;  I  shall  take  care  to  do  this  for  each  nerve. 

Relations. — At  its  origin  it  is  situated  between  the  scaleni,  which  cover  it  for  a  great- 
er extent  below  than  above.  A  very  strong  aponeurosis,  which  extends  over  it  and  the 
scaleni  also,  completely  isolates  it  from  the  surrounding  parts. 

Lower  down,  it  is  situated  between  the  clavicle  and  sub-clavius  muscle  on  the  one 
hand,  and  the  first  rib  and  upper  part  of  the  serratus  magnus  on  the  other. 

Still  lower,  it  is  contained  in  the  cavity  of  the  axilla,  separated  from  the  pectoral- 
is  major  in  front  by  the  costo-clavicular  aponeurosis,  and  resting  upon  the  scapulo-hu- 
meral  articulation  behind,  from  which  it  is  separated  by  the  tendon  of  the  sub-scapularis. 

The  following  are  its  relations  with  the  axillary  artery :  Between  the  scaleni  and  be- 
low them,  the  artery  is  situated  upon  the  same  plane  as  the  brachial  plexus,  and  lies  be- 
tween the  plexus  and  the  first  rib.  Lower  down  it  is  placed  on  the  anterior  part  of  the 
plexus ;  at  the  lower  extremity  of  the  plexus  it  passes  under  the  angle  of  union  of  the 
two  roots  of  the  median  nerve,  by  which  it  is  embraced ;  the  axillary  vein  always  lies 
in  front  of  the  artery,  and  therefore  has  less  direct  rela- 
tions with  the  plexus. 

The  branches  of  the  brachial  plexus  may  be  divided 
into  the  collateral  and  the  terminal. 

The  terminal  branches  are  five  in  nimiber,  namely,  the 
internal  cutaneous  {g,  fig.  286)  and  its  accessory,  the  mus- 
culo-cutaneous  {b),  the  median  (c),  the  radial  or  musculo- 
spiral  (/),  and  the  ulnar  {d)  nerves.* 

The  collateral  branches  may  be  divided  into  those  giv- 

*  I  think  it  right  to  class  the  circumflex  nerve  among  the  collateral  branches,  and  not,  like  most  authors, 
among  the  terminal  branches  of  the  plexus. 


^^2  NEUROLOGY. 

en  off  above  the  clavicle,  namely,  the  nerve  for  the  suh-clavius,  those  for  t^eJevator  angu 
li  scapula  and  rhomboidcus,  the  posterior  thoracic  or  nerve  for  the  serratus  magnus,  the  su- 
pra-scapular  nerve  (a)  or  nerve  for  the  supra-  and  infra-spinati  muscles,  and  the  superior  sub- 
scapular nerve ;  those  given  off  opposite  the  clavicle,  namely,  the  thoracic  branches ;  and 
those  given  off  in  the  axilla,  namely,  the  circumflex  nerve  (e)  and  the  sub-scapular  branches^ 
which  comprehend  the  nerve  for  the  latissimus  dorsi,  the  nerve  for  the  teres  major,  and  the 
inferior  scapular  nerve. 

One  hranch  only,  namely,  the  nerve  for  the  sub-clavius  muscle,  arises  from  the  front 
part  of  the  brachial  plexus  :  all  the  other  collateral  branches  are  given  off  from  the  back 
of  the  plexus. 

The  Collateral  Branches  of  the  Brachial  Plexus. 

The  Branches  given  off  below  the  Clavicle. 

The  Nerve  for  the  Sub-clavius  Muscle. — This  is  a  small  but  constant  branch,  which 
comes  off  from  the  fifth  cervical  nerve,  immediately  before  its  junction  with  the  sixth, 
passes  vertically  downward  in  front  of  the  sub-clavian  artery,  and  then  enters  perpendic- 
ularly into  the  middle  of  the  sub-clavius  muscle. 

This  small  nerve,  before  reaciiing  the  sub-clavius,  always  gives  off  a  phrenic  branch, 
which  passes  obliquely  inward  in  front  of  the  sub-clavian  vein,  and  anastomoses  with  the 
phrenic  nerve. 

The  Nerve  for  the  Levator  Anguli  Scapula. — This  branch  arises  as  frequently  from  the 
cervical  as  from  the  brachial  plexus ;  in  the  former  case,  it  arises  from  the  fourth  cervi- 
cal nerve,  in  the  latter  from  the  fifth.  It  arises  from  the  nerve  immediately  after  its  exit 
from  the  canal  of  the  transverse  processes,  turns  round  the  scalenus  posticus  to  gain 
the  deep  surface  'oi  the  levator  anguli  scapulae,  enters  the  muscle,  supplies  it  with  a 
great  number  of  filaments,  and  perforates  it  to  reach  the  rhomboideus,  under  which  it 
passes.  One  of  its  terminating  filaments  anastomoses  with  a  filament  from  the  proper 
nerve  for  the  rhomboideus. 

The  Nerve  for  the  Rhomboideus. — ^This  arises  from  the  fifth  cervical  nerve,  immediately 
below  the  preceding ;  I  have  seen  it  arise  by  a  common  trunk  with  the  superior  branch^, 
of  origin  of  the  nerve  for  the  serratus  magnus  ;  it  passes  downward  and  backward  be-  ^ 
tween  the  scalenus  posticus  and  the  levator  anguli  scapulae,  and  then  beneath  the  last-  * 
mentioned  muscle,  nearly  as  far  as  its  scapular  attachments,  in  order  to  get  between  the 
rhomboideus  and  the  ribs  ;  it  may  be  traced  as  far  as  the  lower  part  of  that  muscle.    One 
of  its  filaments  perforates  the  rhomboideus,  and  anastomoses  in  the  trapezius  with  the 
posterior  spinal  nerves. 

The  Nerve  for  the  Serratus  Magnus  {Posterior  Thoracic  Nerve  of  authors  ;  External  Res- 
piratory Nerve,  Sir  C.  Bell). — This  branch,  which  is  very  remarkable  for  the  length  of 
its  course,  is  derived  from  the  fifth  and  sixth  cervical  nerves,  immediately  after  their  exit 
from  the  canal  of  the  transverse  processes  ;  it  arises  by  two  roots,  which  are  sometimes 
equal  and  sometimes  unequal  in  size  ;  it  passes  vertically  downward  behind  the  brachial 
plexus  and  the  axillary  vessels,  in  front  of  the  scalenus  posticus,  reaches  the  side  of  the 
thorax  (e',  fig.  287),  between  the  sub-scapularis  and  the  serratus  magnus,  runs  the  whole 
length  of  the  last-named  muscle,  and  ramifies  in  its  lower  portion. 

During  this  course,  it  gives  off  a  great  number  of  filaments  to  the  muscle :  the  lowest 
of  these  may  be  traced  as  far  as  the  lowest  digitation.     The  branch  which  it  gives  to  the  . 
upper  part  of  the  muscle  is  remarkable  for  its  size. 

I  have  seen  a  branch  from  the  seventh  cervical  nerve  join  the  external  thoracic  nerve  ; 
upon  the  upper  part  of  the  serratus  magnus,  so  that  this  nerve  would  then  be  derived 
from  the  fifth,  sixth,  and  seventh  cervical  nerves. 

The  Supra-scapular  Nerve,  or  Nerve  for  the  Supra-  and  Infra-spinati  Muscles. — This  j 
branch  (a,  fig.  286)  is  given  off  from  the  back  part  of  the  fifth  cervical  nerve  at  its  junc- 
tion with  the  sixth  ;  it  passes  obliquely  backward,  outward,  and  downward,  dips  beneath  ,, 
the  trapezius,  and  then  under  the  omo-hyoid,  the  direction  of  which  it  nearly  follows, 
and  gradually  increases  in  size  as  it  approaches  the  coracoid  notch  of  the  scapula,  and 
passes  by  itself  under  the  ligament  which  converts  this  notch  into  a  foramen  ;  the  supra- 
scapular artery  and  vein,  which  had  hitherto  been  in  contact  with  the  nerve,  leave  it  op- 
posite this  notch  to  pass  above  the  ligament,  and  then  join  it  again  in  the  supra-spinous 
fossa. 

The  nerve  then  runs  from  before  backward  in  the  supra-spinous  fossa,  protected  by  a  .^ 
thick  fibrous  lamella,  reaches  the  free  concave  border  of  the  spine  of  the  scapula,  against" 
which  it  is  held  by  a  fibrous  band,  is  then  reflected  inward  and  downward  over  this  con-  ,j 
cave  border  to  gain  the  infra-spinous  fossa,  and  immediately  divides  into  two  branches,  ,.^ 
one  of  which  spreads  out  in  the  upper  part,  and  the  other  in  the  lower  part  of  the  infra-  ,^ 
spinatus  muscle. 

During  its  course  through  the  supra-spinous  fossa,  the  supra-scapular  nerve  gives  off 
two  supra-spinous  branches,  one  of  which  is  detached  opposite  the  coracoid  notch,  and 
the  other  upon  the  spine  of  the  scapula.    They  both  enter  the  supra-spinatus  muscle.      » 


BRANCHES  BELOW  THE  CLAVICLE.  783 

The  supra-scapular  nerve  is  exclusively  destined  for  the  supra-  and  infra-spinati  mus- 
cles.   It  gives  no  filament  to  the  sub-scapularis. 

The  Superior  Sub-scapular  Nerve. — This  is  a  very  small  branch  which  arises  imme- 
diately above  the  clavicle,  and  passes  downward  and  forward  to  reach  the  upper  border 
of  the  sub-scapularis,  and  then  enters  that  muscle. 

The  Branches  given  off  opposite  to  the  Clavicle. 

These,  which  are  named  the  thoracic  branches,*  are  generally  two  in  number,  one  an- 
terior, the  other  ;?os^mor :  they  arise  from  the  anterior  part -of  the  brachial  plexus,  oppo- 
site the  sub-clavius  muscle.  The  anterior  branch,  or  nerve  for  the  pectoralis  major,  which 
is  the  larger,  passes  downward  and  forward  between  the  sub-clavius  muscle  and  the  sub- 
clavian vein,  and  divides  into  two  branches :  an  external,  or  anastomotic,  which  some- 
times arises  directly  from  the  brachiad  plexus,  and  forms  a  loop  around  the  axillary  ar- 
tery, by  anastomosing  with  the  posterior  thoracic  branch  ;  and  an  internal,  which  runs 
along  the  deep  surface  of  the  pectoralis  major,  and  expands  into  a  great  number  of  re- 
markably long  and  slender  filaments,  which  enter  the  muscle  very  obliquely,  and  may  be 
traced  as  far  as  its  sternal  attachments.  A  very  slender  filciment  is  constantly  foimd 
running  along  the  clavicle. 

The  posterior  thoracic  branch,  or  nerve  for  the  pectoralis  miner,  passes  behind  the  axillary 
artery,  below  which  it  curves  forward,  to  form,  with  the  external  branch  of  the  anterior 
thoracic,  the  anastomotic  loop  of  which  I  have  already  spoken.  From  this  loop  or  arch, 
in  forming  which  the  nervous  filaments  are  separated  from  each  other,  two  sets  of 
branches  proceed :  the  one  set  runs  between  the  pectoralis  major  and  minor,  closely 
applied  to  the  former  muscle,  which  they  then  enter,  diverging  to  its  lowest  part ;  the 
others  pass  beneath  the  pectoralis  minor,  and  penetrate  its  deep  surface ;  some  of  them 
pass  obliquely  through  this  muscle  and  join  the  anterior  thoracic  branches  in  the  pecto- 
ralis major. 

The  Branches  given  off  below  the  Clavicle. 

The  Axillary  or  Circumflex  Nerve. — This  is  no  less  remarkable  for  its  great  size,  which 
has  led  some  anatomists  to  regard  it  as  a  terminal  branch  of  the  brachial  plexus,  than 
for  its  reflected  course  :  it  comes  off  from  the  back  of  the  plexus,  behind  the  musculo- 
spiral  nerve,  or,  rather,  the  circumflex  and  musculo-spiral  nerves  (e  and  f,  fig.  286)  ap- 
pear to  be  the  two  divisions  of  a  trunk  formed  by  filaments  from  the  five  branches  of  the 
brachial  plexus. 

Immediately  after  its  origin,  the  circumflex  nerve  passes  downward  and  outward  (g, 
fig.  288)  in  front  of  the  sub-scapularis,  which  separates  it  from  the  shoulder-joint,  turns 
obliquely  round  the  lower  border  of  that  muscle,  round  the  back  part  of  the  articulation, 
and,  lastly,  round  the  surgical  neck  of  the  humerus,  is  then  reflected  upward,  so  as  to  de- 
scribe a  curve  with  the  concavity  turned  in  the  same  direction,  and  terminates  by  ram- 
ifying in  the  deltoid. 

During  this  curved  course,  the  circumflex  nerve,  accompanied  by  the  posterior  cir- 
cumflex vessels,  passes  at  first  between  the  sub-scapularis  and  the  teres  major,  then  be- 
low the  teres  minor,  on  the  outer  side  of  the  long  head  of  the  triceps  (i.  e.,  next  to  the 
bone),  and  then  lies  in  contact  with  the  deep  surface  of  the  deltoid,  against  which  it  is 
held  by  a  very  dense  layer  of  fascia. 

The  relation  of  the  circumflex  nerve  to  the  articulation  explains  the  possible  occur- 
rence of  laceration  of  this  nerve  in  luxations  of  the  humerus  downward. 

The  collateral  branches  of  the  circumflex  nerve  are  three  in  number.  One  branch  almost 
always  goes  to  the  sub-scapularis.  I  have  already  said  that  the  sub-scapular  nerves 
might  be  regarded  as  branches  of  the  circumflex. 

As  it  turns  round  the  lower  border  of  the  sub-scapularis,  the  circumflex  gives  off  a 
branch  for  the  teres  minor  and  the  cutaneous  branch  of  the  shoulder. 

The  nerce  for  the  teres  minor  enters  that  muscle  by  its  lower  border  ;  it  almost  always 
arises  by  a  common  trunk  with  a  deltoid  branch,  which  runs  upward  and  backward  to 
supply  the  back  part  of  the  deltoid  muscle. 

The  cutaneous  nerve  of  the  shoulder  frequently  arises  by  a  common  trunk  with  the  two 
preceding,  and,  in  this  case,  the  circumflex  nerve  appears  to  bifurcate  ;  it  passes  under 
the  posterior  border  of  the  deltoid,  then  lies  in  contact  with  the  skin  covering  the  back 
part  of  the  top  of  the  shoulder,  and  divides  into  diverging  branches,  some  ascending,  oth- 
ers descending,  and  others  running  horizontally.  A  second,  and  sometimes  a  third  cu- 
taneous branch  perforates  the  fleshy  fibres  of  the  deltoid,  and  is  distributed  to  the  corre- 
sponding skin. 

The  terminal  or  deltoid  branches  of  the  circumflex  nerve  are  given  off  as  that  nerve  is  turn  ■ 
ing  round  the  neck  of  the  humerus,  in  which  situation  it  divides  into  several  diverging 
branches,  the  superior  of  which  ascends,  and  appears  like  the  continuation  of  the  nerve, 
while  the  others  descend,  and  may  be  traced  as  far  as  the  insertion  of  the  muscle  into  the 
humerus. 

*  The  anterior  thoracic  nerves  of  those  who  name  the  nerve  for  the  serratus  magnus  the  posterior  thoracic 


784 


NEUROLOGY. 


Tlie  Sub-scapular  Nerves. — The  nerve  for  the  latissimns  dor  si  is  the  largest  of  the  nerves 
generally  described  as  the  sub-scapular ;  it  comes  off  at  an  acute  angle  from  the  inside  of 
the  circumflex  nerve,  and  descends  vertically  in  the  midst  of  the  cellular  tissue  of  the 
axilla,  between  the  sub-scapularis  and  serratus  magnus,  parallel  to  the  external  thoracic 
nerve,  which  it  greatly  resembles  in  size  and  direction  as  well  as  in  its  length ;  it  then 
passes  in  front  of  the  latissimus  dorsi,  reaches  its  outer  border,  and  may  be  traced  down 
to  the  lower  part  of  that  muscle. 

The  nerve  for  the  teres  major  arises  at  a  very  acute  angle  from  the  preceding  nerve,  to 
the  inner  side  of  which  it  runs  ;  it  passes  to  the  sub-scapularis,  turns  round  its  outer  bor- 
der, and  enters  the  anterior  surface  of  the  teres  major  by  a  great  number  of  filaments. 

The  inferior  sub-scapular  nerve  {I,  Jig-  288)  is  sometimes  multiple,  and  presents  many 
varieties  in  its  origin  and  number.  Thus,  it  sometimes  curves  directly  from  the  brachial 
plexus ;  sometimes  from  a  common  tnmk  with  the  circumflex  nerve.  Again,  it  often 
arises  by  a  common  trunk  with  the  nerve  for  the  teres  major.  Whatever  be  its  origin, 
and  whether  it  be  single  or  multiple,  it  enters  immediately  into  the  sub-scapularis,  and 
terminates  there. 

We  have  seen  that  a  small  branch  given  off  from  the  brachial  plexus  above  the  clavi- 
cle, the  superior  sub-scapular  nerve,  enters  the  same  muscle  at  its  upper  border. 

The  Terminal  Branches  op  the  Brachial  Plexus. 
The  Internal  Cutaneous  Jferve  and  its  Accessory. 
^-  287.  The  internal  cutaneous  nerve  (g,  fig.  286),  the  most  internal 

and  the  smallest  of  the  terminal  branches  of  the  brachial  plex- 
us, arises  by  a  common  trunk  with  the  ulnar  nerve  (</)  and 
the  internal  root  of  the  median  (c) :  concealed  at  first  by  the 
axillary  artery,  it  descends  vertically  (a,  Jig.  288)  to  the  inner 
side  of  the  median  nerve,  and  in  front  of  the  basilic  vein  :  at 
the  upper  part  of  its  course  it  lies  beneath  the  fascia,  but  it 
becomes  sub-cutaneous  at  the  same  time  as  the  basilic  vein 
{b,  fig.  287),  and  is  then  separated  from  the  median  nerve  by 
the  brachial  aponeurosis ;  at  the  middle  of  the  arm,  it  divides 
into  two  terminal  branches,  an  external,  anterior  or  ulnar,  and 
an  internal,  posterior  or  cpitrochlear.  The  internal  cutaneous 
gives  off  only  one  branch  during  its  course  along  the  arm, 
namely,  a  cutaneous  branch,  which  varies  in  size  as  well  as  in 
the  situation  at  which  it  is  given  off:  this  cutaneous  branch 
arises  in  the  cavity  of  the  axilla,  often  anastomoses  with  an 
intercostal  nerve,  is  applied  against  the  skin  on  the  inner  as- 
pect of  the  arm,  and  may  be  traced  as  far  as  the  elbow.* 

Terminal  Branches. — The  anterior,  external  or  ulnar  branch, 
which  is  the  larger,  continues  in  the  vertical  direction  of  the 
trunk  of  the  nerve,  and  divides  into  two  branches,  which  de- 
scend in  front  of  the  elbow-joint,  sometimes  before,  and  some- 
times behind  the  median  basihc  vein  (e),  and  again  subdivide 
into  a  great  number  of  filaments  which  diverge,  and  are  ar- 
ranged in  the  following  manner  :  the  internal  filaments  pass 
obliquely  downward,  inward,  and  backward,  crossing  the  ul- 
nar vein  (m),  and  then  the  ulna,  and  supply  the  skin  covering 
the  inner  and  back  part  of  the  forearm  ;  they  can  be  traced 
nearly  as  far  as  the  region  of  the  carpus  :  the  external  fila- 
ment, which  might  be  called  median,  because  it  follows  the 
median  vein,  descends  vertically,  and  may  be  traced  as  far  as 
the  upper  part  of  the  palm  of  the  hand  ;  one  of  these  filaments 
always  anastomoses  with  a  twig  from  the  ulnar  nerve  at  the 
lower  part  of  the  forearm. 

The  posterior,  internal  or  epitrochlear  branch  (g),  descends  ver- 
tically behind  the  median  basilic  vein,  in  front  of  the  epitroch- 
lea,  and  then  below  it,  so  as  to  embrace  it  in  a  sort  of  loop  ; 
it  then  passes  very  obliquely  downward  and  backward,  cross- 
es the  ulna  below  the  olecranon,  gains  the  dorsal  aspect  of 
the  forearm,  and  runs  vertically  (a,  fig.  289)  down  to  the  wrist. 
Around  the  epitrochlea,  this  internal  branch  gives  off  several 
branches,  which  ramify  upon  the  skin  that  covers  the  inner 
side  of  the  elbow-joint :  one  of  these  branches  is  reflected  up- 
ward between  the  epitrochlea  and  the  olecranon,  and  anasto- 
moses with  the  accessory  nerve  of  the  internal  cutaneous. 

*  I  have  always  found  a  remarkably  long  and  slender  filament  arising  from  the  internal  cutaneous  nerve  at 
the  upper  part  of  the  arm  ;  it  runs  along  that  nerve,  passes  beneath  the  basilic  vein,  and  then  lies  in  contact  with 
the  fascia,  which  it  perforates  near  the  epitrochlea,  and  is  lost  upon  the  synovial  membrane  of  the  elbow-joint. 


THE   MUSCULO-CUTANEOUS  NEEVE.  1^5 

Frequently,  before  reaching  the  epitrochlea,  this  branch  has  already  given  off  a  twig 
which  anastomoses  with  the  same  nerve. 

Summary. — The  internal  cutaneous  nerve,  then,  is  exclusively  intended  for  the  skin.  It 
only  gives  one  small  branch  to  the  arm  :  its  other  divisions  are  intended  for  the  forearm. 
One  of  them  belongs  to  the  dorsal,  and  the  other  to  the  internal  aspect. 

The  Accessory  Nerve  of  the  Internal  Cutaneous. — I  have  applied  this  term  to  a  small 
branch  (cutaneus  minor  internus,  Wrisberg),  which  it  is  difficult  to  discover,  and  which 
would  be  more  properly  classed  among  the  collateral  than  the  terminal  branches  of  the 
brachial  plexus  :  it  arises  above  and  sometimes  below  the  clavicle,  from  the  back  part 
of  the  nervous  cord  formed  by  the  junction  of  the  eighth  cervical  and  first  dorsal  nerves  : 
it  passes  downward  upon  the  sides  of  the  thorax,  and  divides  into  two  branches,  an  ex- 
ternal and  an  internal. 

The  external  branch  (a',  fig.  287),  which  is  the  smaller  one,  passes  vertically  downward, 
and  crosses  the  conjoined  tendons  of  the  teres  major  and  latissimus  dorsi  at  right  an- 
gles ;  it  lies  in  contact  with  the  skin  covering  the  inner  and  back  part  of  the  arm,  and 
may  be  traced  as  low  as  the  elbow. 

The  internal  branch  (c)  anastomoses  with  the  second  intercostal  nerve,  descends  ver- 
tically, crossing  the  conjoined  tendons  of  the  latissimus  dorsi  and  teres  major,  becomes 
applied  to  the  skin,  and  divides  into  several  very  slender  filaments,  which  correspond  to 
the  internal,  anterior,  and  posterior  regions  of  the  arm,  and  may  be  traced  as  far  as  the 
region  of  the  elbow ;  one  of  these  filaments  anastomoses  with  the  internal  cutaneous.* 

The  Musculo-cutaneous  JSTerve. 

The  musculo-cuta?ieous  nerve  (b,  fig.  286),  the  most  external  of  the  terminal  branches 
of  the  brachial  plexus,  and,  with  the  exception  of  the  internal  cutaneous,  the  smallest, 
arises  by  a  common  trunk  with  the  external  root  of  the  median  nerve  (c),  passes  down- 
ward and  outward,  in  front  of  the  humeral  insertion  of  the  sub-scapularis,  and  on  the 
inner  side  of  the  coraco-brachialis,  which  is  perforated  by  it,  and  is  therefore  called  the 
per/orated  muscle  of  Casserius.f  After  emerging  from  the  muscle,  through  which  it  passes 
very  obliquely,t  the  musculo-cutaneous  nerve  {h,fig.  288)  is  situated  between  the  biceps 
and  the  brachialis  anticus,  continues  its  oblique  course,  escapes  from  beneath  the  outer 
border  of  the  tendon  of  the  biceps,  and  then  becomes  sub-cutaneous. 

During  its  course  along  the  arm  it  gives  off  the  following  branches 

The  branches  for  the  coraco-brachialis  are  two  in  number :  one  superior,  which  enters  the 
upper  part  of  this  muscle,  and  is  then  lost  in  the  short  head  of  the  biceps  ;  the  other  in- 
ferior, which,  in  some  subjects,  after  having  furnished  a  certain  number  of  filaments  to  the 
coraco-brachialis,  becomes  applied  to  the  trunk  of  the  musculo-cutaneous  nerve  itself. 

The  branches  for  the  biceps  are  very  numerous  :  not  uncommonly  they  arise  by  a  com- 
mon trunk,  which  then  appears  to  result  from  the  bifurcation  of  the  musculo-cutaneous. 
One  of  these  branches  perforates  the  biceps,  and  passes  transversely  outward  to  reach 
the  elbow-joint,  to  which  it  is  distributed. 

The  branches  for  the  brachialis  anticus  almost  always  arise  by  a  large  common  trunk 
which  appears  to  result  from  a  farther  bifurcation  of  the  nerve,  already  diminished  one 
half,  after  it  has  supplied  the  branches  for  the  biceps.  While  these  last-named  branches 
enter  the  posterior  surface  of  the  corresponding  muscle,  the  branches  for  the  brachialis 
anticus  penetrate  that  muscle  by  its  anterior  surface. 

After  having  given  off  all  these  muscular  branches,  the  musculo-cutaneous  nerve,  re- 
duced to  a  fourth  or  a  fifth  of  its  original  size,  is  distributed  entirely  to  the  skin  ;  it  passes 
vertically  downward  in  front  of  the  elbow-joint,  behind  the  median  cephalic  vein  {a,  fig. 
287),  and  divides  into  two  terminal  branches,  of  which  the  internal  (A)  runs  along  the 
inner,  and  the  external  along  the  outer  side  of  the  radial  vein. 

These  two  branches,  during  their  course  along  the  forearm,  lie  between  the  fascia  of 
the  forearm  and  the  superficial  fascia ;  they  gradually  diminish  in  size  as  they  give  off 
their  filaments  to  the  skin,  and  terminate  in  the  following  manner  : 

The  external  branch  passes  to  the  dorsal  surface  of  the  forearm,  and  may  be  traced  as 
far  as  the  skin  which  covers  the  carpus. 

The  internal  branch  has  a  more  extensive  distribution  ;  it  anastomoses  with  a  branch 
of  the  radial  nerve  at  the  lower  part  of  the  forearm,  and  gives  off  a  deep  or  articular 
branch,  which  divides  into  several  twigs  that  surround  the  radial  artery.  One  of  these 
twigs  expands  into  a  number  of  filaments  which  enter  the  fore  part  of  the  radio-carpal 
articulation  ;  the  others  accompany  the  radial  artery  in  its  oblique  course  upon  the  outer 
side  of  the  carpus,  and  then  spread  out  to  terminate  on  the  back  part  of  the  synovial 
membrane  of  the  wrist-joint.  After  having  given  off  this  very  remarkable  articular 
branch,!^  the  internal  terminal  division  of  the  musculo-cutaneous  nerve  passes  in  front 

*  [And  with  the  internal  cutaneous  branch  of  the  musculo-spiral  nerve.] 
t  [The  nerve  is  also  called  perforans  Casserii.l 

X  Not  unfrequeutly  the  nerve  does  not  perforate  the  coraco-brachialis.     [It  sometimes  has  an  anastomosis 
iMth  the  median  nerve  after  emerging  from  the  coraco-brachialis.] 
t  In  one  subject,  the  articular  filaments  had  some  gangliform  enlargements  on  their  sides  precisely  similar 

5G^ 


me 


NEUROLOGY. 


of  the  tendons  of  the  extensor  brevis  poUicis  and  abductor  longus  poUicis,  in  front  of  and 
more  superficially  than  the  corresponding  branch  of  the  radial  nerve,  and  then  divides 
into  several  twigs,  which  are  intended  for  the  skin  of  the  thenar  eminence.  One  of 
these  branches,  which  runs  along  the  outer  side  of  that  eminence,  may  be  traced  into 
the  skin  upon  the  first  phalanx  of  the  thumb. 

Summary. — The  musculo-cutaneous  nerve,  then,  supplies  certain  muscular  branches, 
which  belong  exclusively  to  the  coraco-brachialis,  the  biceps,  and  the  brachialis  anticus  ; 
the  section  of  this  nerve  would,  therefore,  destroy  the  power  of  flexing  the  forearm  : 
certain  cutaneous  branches  to  the  skin  on  the  outer  side  of  the  forearm  and  hand  ;  and, 
lastly,  some  articular  branches  to  the  elbow  and  to  the  wrist. 

The  Median  Jferve. 
The  median  nerve  (c.  Jig.  286),  one  of  the  terminal  branches  of  the  brachial  plexus, 
arises  from  the  plexus  by  two  very  distinct  roots  between  the  musculo-cutaneous  (i)  on 
the  outer  side,  and  the  ulnar  nerve  {d)  on  the  inner.*  The  internal  root  arises  from  a 
nervous  cord  which  is  common  to  it,  to  the  ulnar,  and  to  the  internal  cutaneous  (g). 
The  external  root  arises  from  a  cord  common  to  it  and  to  the  musculo-cutaneous.  The 
axillary  artery  passes  between  these  two  roots. 

The  trunk  resulting  from  the  union  of  these  two  roots  is  situated  on  the  inner  side 
of  the  axillary  artery ;  it  is  at  first  grooved  to  receive  the  inner  half  of  tho  artery,  but  it 
soon  forms  a  rounded  cord,  proceeds  vertically  downward  (c.  Jig.  288),  gains  the  middle 
and  fore  part  of  the  elbow-joint,  dips  between  the  muscles  on  the  anterior  region  of  the 
forearm  (rf),  and  passes  behind  the  annular  ligament  to  enter  the  palm  of  the  hand  (r), 
where  it  terminates  by  dividing  into  six  branches.  We  shall  examine  it  in  the  arm,  the 
forearm,  and  the  hand. 

•Pifi".  288.  In  the  Arm. 

The  median  nerve  (c),  which  is  straight  and  vertical, 
and  the  satellite  nerve  of  the  brachial  artery,  passes  some- 
what obliquely  downward,  forward,  and  outward,  to  the 
middle  and  fore  part  of  the  elbow-joint. 

Relations. — On  the  inner  side  it  is  sub-aponeurotic,  so 
that  when  the  arm  is  held  away  from  the  side,  and  the 
forearm  is  extended  upon  the  arm,  it  projects  below  the 
skin  like  a  tense  cord,  which  is  very  distinctly  seen  in 
emaciated  subjects. 

On  the  outside,  it  corresponds  at  first  to  the  brachialis 
anticus,  and  is  then  received  in  the  sort  of  groove  formed 
between  the  inner  border  of  the  biceps  and  the  brachialis 
anticus. 

In  front,  it  is  covered  by  the  inner  border  of  the  biceps, 
excepting  in  emaciated  subjects. 

Behind,  it  is  in  relation  with  the  ulnar  nerve  (/),  and  then 
with  the  brachialis  anticus. 

Its  relations  with  the  brachial  artery  are  of  the  greatest 
importance,  in  reference  to  the  application  of  a  ligature  to 
that  vessel.  The  nerve  is  at  first  situated  to  the  outer  or 
radial  side  of  the  axillary  artery,  but  soon  passes  in  front  of 
the  vessel,  and  then  it  crosses  over  slightly,  so  that  at  the 
bend  of  the  elbow  it  is  situated  about  two  lines  to  the  inner 
or  ulnar  side  of  the  artery.  This  last  relation  is  not  con- 
stant :  I  have  seen  the  nerve  on  the  outer  side  of  the  artery 
at  the  bend  of  the  elbow. 

The  following  are  its  relations  with  the  other  nerves :  the 
internal  cutaneous  nerve  runs  along  its  inner  side,  at  first 
immediately  in  contact  with  it,  and  then  separated  from  it 
by  the  fascia  of  the  arm. 

The  ulnar  nerve  runs  behind  it  in  the  upper  third  of  the 
arm,  and  is  then  separated  from  it,  so  that  the  two  nerves 
bound  the  sides  of  a  triangular  interval,  the  base  of  which 
is  below  and  the  apex  above. 

The  median  nerve  does  not  give  any  branch  in  the 
arm.t 

to  those  which  are  met  with  on  the  cutaneous  nerves  in  the  palm  of  the 
hand  ;  the  articular  filaments,  moreover,  have  almost  always  the  grayish 
aspect  of  the  nerves  of  organic  life.  .     ,  ,   ^,  , 

*  These  two  roots  of  the  median  nerve,  when  united  to  the  raiisculo-cu 
taneous  and  the  ulnar,  represent  very  nearly  a  capital  M.  ^ot  unfre 
quently  there  is  a  third  internal  root  for  the  median  nerve. 

t  [Except,  occasionally,  an  anastomotic  branch  to  the  musculo-cutane 
ous,  after  the  latter  has  emerged  from  the  coraco-brachialis.] 


THE    MEDIAN    NERVE   IN    THE   FOREARM   AND    HAND.  787 

In  the  Forearm. 
TTie  median  nerve,  like  the  brachial  artery,  to  the  inner  side  of  which  it  is  generally 
situated,  passes  beneath  the  tendinous  expansion  of  the  biceps,  and  is  separated  from 
the  elbow-joint  by  the  brachialis  anticus. 

It  almost  always  perforates  the  pronator  teres  in  such  a  manner  as  to  leave  only  a 
very  small  tongue  of  fleshy  fibres  behind  it;*  it  then  passes  (rf,  fig.  288)  between  the 
flexor  sublimis  and  flexor  profundus  digitorum,  opposite  the  cellular  interval  between 
the  latter  muscle  and  the  flexor  longus  poUicis  :  at  the  lower  part  of  the  forearm  it  runs 
along  the  outer  border  of  the  flexor  sublimis,  where  it  might  be  easily  exposed  between 
the  tendon  of  the  palmaris  longus  on  the  inside,  and  of  the  flexor  carpi  radialis  on  the 
outside.  I  have  seen  this  nerve  perforate  the  upper  part  of  the  flexor  sublimis,  which 
formed  a  sheath  for  it. 

Branches. — These  are  muscular,  excepting  the  palmar  cutaneous,  which  arises  at  the 
lower  part  of  the  forearm  :  they  supply  all  the  muscles  of  the  anterior  region  of  the  fore- 
arm except  a  part  of  the  flexor  profundus,  and  the  whole  of  the  flexor  carpi  ulnaris, 
which  receive  branches  from  the  ulnar  nerve.  Lastly,  with  the  exception  of  the  palmar 
cutaneous,  the  branches  arise  near  the  bend  of  the  elbow. 

The  branch  for  the  ^pronator  teres  comes  off  from  the  anterior  part  of  the  median  nerve, 
a  little  above  the  elbow-joint,  and  passes  downward  to  enter  the  substance  of  the  mus- 
cle. It  gives  off  several  articular  filaments,  which  dip  from  before  backward,  around  the 
termination  of  the  brachial  artery  and  the  commencement  of  the  radial  and  ulnar  arter- 
ies, form  loops  with  their  concavities  turned  upward  in  the  angle  of  bifurcation  of  the 
brachial,  and  then  enter  the  articulation. 

The  other  collateral  branches  of  the  median  in  the  forearm  arise  from  its  posterioi 
aspect :  they  are  the  branch  for  the  superficial  layer  of  muscles,  which  arises  opposite  the 
elbow-joint,  and  then  divides  successively  into  several  others,  which  enter  the  pronator 
teres,  the  flexor  carpi  radialis,  the  palmaris  longus,  and  the  flexor  sublimis.  The  filaments 
for  the  flexor  sublimis  are  remarkably  slender,  and  are  reflected  upward  below  the  epi- 
trochlea :  they  belong  to  the  upper  part  only  of  this  muscle,  which  is  also  supplied  by 
two  or  three  other  branches,  given  off  in  succession  from  the  median,  a  little  below  the 
bend  of  the  elbow. 

The  branch  for  the  deep  layer  of  muscles  is  a  large  trunk,  which  soon  divides  into  sev- 
eral branches,  viz.,  one  external,  for  the  flexor  longus  pollicis,  the  upper  extremity  of 
which  it  enters  ;  two  internal,  which  enter  the  flexor  profundus,  but  only  supply  its  inner 
half,  the  other  half  receiving  its  nerves  from  the  ulnar  ;t  and  a  middle  branch,  the  inter- 
osseous nerve  (e),  which  requires  a  particular  description.  It  passes  vertically  downward, 
in  front  of  the  interosseous  ligament,  between  the  flexor  profundus  and  the  flexor  lon- 
gus pollicis,  to  both  of  which  it  gives  several  filaments  ;  having  reached  the  upper  bor- 
ders of  the  pronator  quadratus,  it  passes  behind  that  muscle  and  divides  into  a  great 
number  of  filaments,  some  of  which  penetrate  the  muscle  from  behind,  while  others  de 
scend  to  gain  the  lower  part  of  the  muscle.  I  have  seen  the  interosseous  nerve  per- 
forate the  interosseous  ligament,  run  a  very  short  distance  upon  its  posterior  surface, 
then  pass  through  it  again,  and  ramify  in  the  pronator  muscle. 

The  palmar  cutaneous  branch  (i,  fig.  287)  comes  off  from  the  median  nerve  opposite  the 
junction  of  the  three  upper  fourths  with  the  lower  fourth  of  the  forearm,  runs  along  the 
median  nerve,  and  divides  into  two  branches,  which  perforate  the  fascia  of  the  forearm 
immediately  above  the  annular  ligament.  The  external  branch  is  the  smaller,  and  cross- 
es obliquely  over  the  tendon  of  the  flexor  carpi  radialis,  and  terminates  in  the  skin  upon 
the  ball  of  the  thumb  ;t  the  internal  branch,  which  is  larger,  descends  vertically  in  front 
of  the  annular  ligament  and  beneath  the  skin,  from  which  it  is  separated  by  a  layer  of 
adipose  tissue,  and  is  lost  in  the  palm  of  the  hand,  much  sooner  than  might  be  expected 
from  its  size  ;^  it  can  scarcely  be  traced  as  far  as  the  middle  of  the  palm. 

In  the  Hand. 
The  median  nerve,  while  passing  behind  the  annular  ligament  of  the  carpus,  becomes 
considerably  wider  and  flattened ;  it  might  even  be  said  to  increase  gradually  in  size. 
Immediately  after  it  has  passed  below  the  ligament,  still  flattened  out,  it  divides  (r)  into 
two  branches,  one  internal,  the  other  external,  which  are  themselves  subdivided ;  the  in- 
ternal into  two,  and  the  external  into  four  branches,  so  that  in  aU  there  are  six  terminal 
branches. 

*  In  one  case,  in  which  the  humeral  attachments  of  the  pronator  teres  were  as  high  as  those  of  the  supina- 
tor longus,  the  median  nerve  passed  through  the  highest  attachments  of  the  pronator  teres,  and  was  situated 
between  the  brachialis  anticus  and  that  muscle,  which  also  covered  it  at  the  bend  of  the  elbow;  in  this  same 
case,  the  brachial  artery  divided  into  the  radial  and  ulnar  at  the  middle  of  the  arm  ;  and  the  ulnar  artery  ap- 
plied against  the  nerve  had  the  same  relations  as  the  brachial  artery  in  ordinary  cases. 

t  All  the  deep  branches  may  be  traced  as  far  as  the  periosteum  of  the  bones  of  tlie  forearm.  [Some  of  them 
have  been  seen  to  communicate  with  filaments  of  the  ulnar  nerve.] 

t  [This  tirauch  anastomoses  with  the  terminal  cutaneous  division  of  the  musculo-spiral  or  radial  nerve.] 

^  This  sudden  mode  of  termination  is  common  to  all  nerves  of  sensation,  which  are  often  Uist  almost  imme- 
diately in  the  skin  ;  the  nerves  of  motion,  on  the  other  hand,  run  a  very  h)nsr  course  as  filaments  licforf  thev 
terminate  in  the  muscles. 


788  NEUROLOGY. 

Tho,  terminal  branches  of  the  median  nerve.  Of  these  one  only  is  muscular,  and  oe- 
longs  to  the  muscles  of  the  ball  of  the  thumb  ;  the  other  five  are  intended  for  the  integ- 
uments of  the  fingers,  of  vi^hich  they  form  the  palmar  collateral  nerves. 

The  branch  for  the  muscles  of  the  ball  of  the  thumb  is  a  recurrent  nerve  ;  it  arises  from 
the  front  of  the  median,  passes  upward  and  outward,  forming  a  horizontal  curve  with 
the  concavity  turned  upward,  perforates  the  superficial  layers  of  the  flexor  brevis,  im- 
mediately gives  off  a  descending  branch  to  that  muscle,  and,  continuing  to  ascend  itself, 
is  divided  almost  equally  between  the  abductor  brevis  and  the  opponens  pollicis. 

The  External  Collateral  Branch  of  the  Thumb* — This  nerve  passes  obliquely  down- 
ward and  outward,  on  the  inner  side  of  the  tendon  of  the  flexor  longus  pollicis,  crosses 
the  metacarpo-phalangal  articulation,  to  gain  the  external  border  of  the  anterior  surface 
of  the  thumb,  and,  running  along  the  outer  side  of  the  tendon  of  the  long  flexor,  arrives 
at  the  ungual  phalanx.  On  this  phalanx,  it  divides  into  two  branches,  a  dorsal  or  ungiud, 
properly  so  called,  which  turns  round  the  side  of  the  phalanx,  anastomoses  with  the  dor- 
sal collateral  branches  of  the  radial  nerve,  and  is  distributed  to  the  dermis  beneath  the 
nail ;  and  a  palmar,  which  is  lost  in  the  skin  covering  the  pulp  of  the  thumb.  Some  of 
these  latter  filaments  turn  round  the  tip  of  the  phalanx,  and  are  distributed  to  the  skin 
beneath  the  nail.  None  of  the  filaments  of  the  external  collateral  branch  anastomose 
with  those  of  the  internal  collateral. 

The  internal  collateral  branch  for  the  thumb  is  less  oblique  in  its  course  and  larger  than 
the  preceding ;  it  nins  along  the  first  interosseous  space  in  front  of  the  adductor  pollicis, 
and  reaches  the  inner  side  of  the  anterior  surface  of  the  thumb,  along  the  tendon  of  the 
long  flexor,  and  terminates  like  the  preceding  branch.  This  branch  gives  oflf  a  twig  to 
the  adductor  pollicis. 

The  external  collateral  branch  for  the  index  finger  sometimes  arises  by  a  common  trunk 
with  the  preceding ;  it  runs  along  the  first  interosseous  space  in  front  of  the  adductor 
pollicis,  on  the  outer  border  of  the  first  lumbricalis  muscle,  to  which  it  gives  a  filament, 
and  then  divides  into  two  branches,  a  dorsal  and  a  palmar :  the  dorsal  branch,  which  is 
the  smaller,  passes  backward  and  downward,  along  the  outer  border  of  the  first  phalanx, 
unites  with  the  dorsal  collateral  branch  derived  from  the  radial  nerve,  gains  the  poste- 
rior surface  of  the  second  phalanx,  and  terminates  upon  the  third,  near  the  nail.  The 
palmar  branch,  which  forms  the  true  continuation  of  the  trunk  of  the  nerve,  is  arranged 
like  the  corresponding  nerve  of  the  thumb,  and  does  not  anastomose  with  the  internal 
collateral  branch. 

The  common  trunk  of  the  internal  collateral  branch  of  the  index  finger,  and  external  collat- 
eral branch  of  the  middle  finger,  passes  vertically  downward,  in  front  of  the  second  inter- 
osseous space,  at  the  middle  of  which  it  divides  into  two  branches,  one  of  which  forms 
the  internal  collateral  branch  of  the  index  finger,  and  the  other  the  external  collateral  branch 
of  the  middle  finger.  These  collateral  nerves,  like  the  preceding,  divide  into  a  dorsal  and 
a  palmar  branch,  the  latter  of  which  again  subdivides  into  a  sub-ungual  branch  and  a 
branch  for  the  pulp  of  the  finger. 

Tlie  common  trunk  of  these  two  collateral  nerves,  before  bifurcating,  gives  ofT  a  twig 
to  the  second  lumbricalis. 

The  common  trunk  of  the  internal  collateral  branch  of  the  middle  finger,  and  external  col- 
lateral branch  of  the  ring  finger,  passes  somewhat  obliquely  inward,  in  front  of  the  third 
interosseous  space,  and  is  distributed  in  the  same  way  as  the  preceding  branches ;  be- 
fore bifurcating,  it  sometimes  gives  a  twig  to  the  third  lumbricalis  ;  it  receives  an  anas- 
tomotic filament  from  the  ulnar  nerve.  The  bifurcation  of  this  sixth  branch  takes  place 
a  little  below  the  metacarpo-phalangal  articulations. 

Relations. — The  following  are  the  relations  of  the  palmar  and  digital  portions  of  the 
median  nerve  : 

Behind  the  anterior  annular  ligament  of  the  carpus,  the  median  nerve  is  situated  on  the 
outer  side  of  the  tendons  of  the  flexor  sublimis  and  in  front  of  those  of  the  flexor  pro- 
fundus :  like  the  tendons  among  which  it  is  placed,  it  is  at  first  covered  by  the  synovial 
membrane  in  front  and  behind. 

In  the  palm  of  the  hand,  the  median  nerve  is  covered  by  the  palmar  fascia,  and  is  situ- 
ated in  front  of  all  the  flexor  tendons.  The  superficial  palmar  arch  lies  in  front  of  it, 
and  crosses  at  right  angles  over  its  three  internal  branches. 

The  collateral  nerves  of  the  fingers  accompany  the  collateral  vessels,  and  pass  with  them 
from  the  palm  of  the  hand  opposite  the  intervals  between  the  metacarpo-phalangal  ar- 
ticulations. Like  the  vessels  which  run  along  their  outer  side,  these  nerves  occupy  the 
borders  of  the  palmar  aspect  of  the  fingers,  one  on  each  side  of  the  tendinous  groove. 

Summary. — From  what  has  been  stated,  it  follows,  then,  that  the  median  nerve  gives 
off  no  branch  in  the  arm  ;t  that,  in  the  forearm,  it  gives  no  nerve  to  the  skin,  but  sup- 
plies all  the  muscles  of  the  anterior  region,  excepting  the  flexor  carpi  ulnaris  and  the 
inner  half  of  the  flexor  profundus,  which  we  shall  see  are  supplied  by  the  ulnar  ;  and, 
lastly,  that,  in  the  hand,  it  supplies  the  cutaneous  nerves  of  the  palm,  the  external  and 

*  I  have  seen  it  arise  after  the  third  branch,  and  upon  a  plane  anterior  to  that  branch,  tlie  oriijin  of"  which 
It  then  crossed.  t  See  note,  p.  7£6. 


THE  ULNAR  NERVE  IN  THE  ARM  AND  FOREARM.         789 

internal  collateral  nerves  of  the  thumb,  index  finger,  and  middle  fingers,  and  the  exter- 
nal collateral  nerve  of  the  ring  finger,  and  also  the  muscular  nerves  of  the  ball  of  the 
thumb  and  the  nerves  of  the  two  outer  lumbricales,  and  sometimes  that  of  the  third 
lumbricalis. 

The  Ulnar  Jferve. 

The  ulnar  nerve  {d,  fig.  286),  a  little  smaller  than  the  preceding,  behind  which  it  is 
situated,  arises  by  a  trunk  which  is  common  to  it,  to  the  internal  root  of  the  median 
nerve  (c),  and  to  the  internal  cutaneous  nerve  (g-) ;  it  passes  vertically  downward  be- 
hind, and  at  first  in  contact  with  the  median,  but  soon  leaves  that  nerve,  and  runs  some- 
what backward  (/,  fig.  288),  while  the  median  is  directed  forward  and  outward  ;  it  per- 
forates the  upper  fibres  of  the  internal  head  of  the  triceps,  and  enters  the  sheath  of  that 
muscle,  behind  the  internal  inter-muscular  septum.  It  thus  gains  the  groove  between 
the  inner  condyle  of  the  humerus  and  the  olecranon,  passes  between  the  two  origins  of 
the  flexor  carpi  ulnaris,  and  is  reflected  from  behind  forward  in  this  groove,  and  then 
upon  the  inner  side  of  the  coronoid  process  :  having  thus  reached  the  anterior  aspect  of 
the  forearm,  it  passes  vertically  downward  (/)  between  the  flexor  carpi  ulnaris  and  the 
flexor  profundus,  and  gains  the  palm  of  the  hand  (s),  where  it  divides  into  its  terminal 
branches.  As  with  the  median  nerve,  we  shall  examine  the  ulnar  in  succession  in  the 
arm,  the  forearm,  and  the  hand. 

In  the  Arm. 

The  most  important  relation  of  this  nerve  (/)  in  the  arm  is  that  at  its  upper  part  with 
the  median  nerve  and  brachial  artery.  It  runs  along  the  inner  side  of  the  artery,  while 
the  median  nerve  is  situated  in  front  of  the  vessel,  or,  rather,  the  artery  is  situated  be- 
tween the  median  and  ulnar  nerves,  so  that  it  may  be  exposed  immediately  below  the 
axilla,  by  separating  these  two  nerves. 

The  ulnar  nerve  gives  off  no  branch  in  the  arm  ;  the  error  of  those  who  have  stated 
the  contrary  has  arisen  from  the  fact  that  the  branch  given  from  the  musculo-spiral 
nerve  to  the  internal  portion  of  the  triceps  lies  in  contact  with  the  ulnar  nerve  for  a 
great  part  of  its  extent,  so  that  it  would  seem  at  first  sight  to  come  off  from  it. 

The  Forearm. 

The  ulnar  nerve  in  the  forearm  (/)  is  at  first  covered  by  the  fleshy  belly  of  the  flexor 
carpi  ulnaris,  which  separates  it  from  the  skin  ;  it  becomes  sub-aponeurotic  below,  where 
the  fleshy  fibres  of  that  muscle  cease,  and  is  found  between  the  tendon  of  the  flexor  carpi 
ulnaris  on  its  inner  side,  and  those  of  the  flexor  sublimis  on  its  outer  side. 

Its  relation  with  the  ulnar  artery  is  remarkable.  This  vessel  describes  a  curve  so  as 
to  reach  the  outer  or  radial  side  of  the  nerve  ;  but  the  nerve  and  artery  are  in  contact 
in  the  lower  third  only  of  the  forearm. 

The  branches  of  this  nerve  in  the  forearm  are  somewhat  numerous.  Between  the  in- 
ternal condyle  and  the  olecranon,  the  ulnar  nerve  gives  several  very  delicate  articular 
filaments,  which  pass  into  the  elbow-joint ;  it  also  gives  off  branches  for  the  flexor  carpi 
ulnaris ;  one  of  which  is  very  large,  and  may  be  traced  as  far  as  the  lower  part  of  the 
fleshy  belly  of  the  muscle. 

After  its  reflection,  the  ulnar  nerve  gives  a  branch  to  the  flexor  profundus  digitorum, 
subdivides,  and  enters  the  substance  of  that  muscle.  Its  divisions  run  upon  the  anterior 
surface  of  the  muscle  before  penetrating  it.  This  branch  is  intended  for  the  two  inner 
portions  of  the  flexor  profundus,  the  two  outer  portions  receiving  their  filaments  from 
the  median  nerve.* 

At  the  middle  of  the  forearm,  a  small,  long,  and  slender  branch  is  given  off  from  the 
anterior  part  of  the  ulnar  nerve,  and  divides  into  two  filaments,  one  of  which  follows  the 
ulnar  artery  (filament  of  the  ulnar  artery),  while  the  other  perforates  the  fascia  of  the  fore- 
arm, and  anastomoses  with  the  internal  cutaneous  nerve  {anastomotic  filament). 

The  internal  dorsal  nerve  of  the  hand  (x)  is  the  largest  of  the  branches  of  the  ulnar 
nerve,  so  that  it  might  be  regarded  as  a  terminal  branch  of  that  nerve  ;  it  is  exclusively 
intended  for  the  skin  of  the  dorsal  region  of  the  hand.  It  comes  off  opposite  the  junc- 
tion of  the  two  upper  thirds  with  the  lower  third  of  the  forearm,  passes  obliquely  down- 
ward, backward,  and  inward  between  the  ulna,  over  which  it  crosses,  and  the  flexor  car- 
pi ulnaris,  and  emerges  (x,  fig.  289)  from  below  the  tendon  of  that  muscle,  a  very  short 
distance  above  the  lower  end  of  the  ulna.  It  then  descends  vertically  between  the  skin 
and  that  part  of  the  bone,  runs  along  the  inner  side  of  the  carpus,  and  divides  into  two 
dorsal  branches,  an  internal  and  an  external. 

The  internal  dorsal  branch  is  the  smaller ;  it  runs  along  the  ulnar  border  of  the  fifth 
metacarpal  bone,  and  along  the  internal  or  ulnar  side  of  the  dorsal  region  of  the  little 
finger,  of  which  it  forms  the  internal  collateral  dorsal  nerve. 

The  external  dorsal  branch  is  much  larger  ;  it  first  gives  off  a  small  anastomotic  ttmg, 
which  crosses  obliquely  over  the  metacarpal  bone,  and  anastomoses  with  a  correspond- 

^   [The  'Inarmay  communicate  in  this  position  with  filauuiit^  pf  the  antenor  interosseous.! 


"m 


NEUROLOGY. 


ingly  oblique  branch  from  the  radial  nerve,  opposite  the  lower  part  of  the  second  interos 
seous  space.  It  then  descends  vertically  along  the  fourth  interosseous  space,  and  di- 
vides into  two  secondary  branches,  which  again  subdivide  to  form  the  dorsal  collateral 
nerves,  in  the  following  manner  :  one  forms  the  external  collateral  nerve  of  the  little  finger, 
and  the  internal  collateral  nerve  of  the  ring  finger ;  and  the  other  the  external  collateral 
nerve  of  the  ring  finger,  and  the  internal  collateral  nerve  of  the  middle  finger.'^ 

In  the  Hand. 

The  ulnar  nerve  enters  the  palm  of  the  hand  {s,fig.  288),  not  by  passing  behind  the  an- 
terior annular  ligament,  but  in  a  special  sheath,  which  is  common  to  it  and  to  the  ulnar 
artery,  is  situated  on  the  inner  side  of  the  annular  ligament,  and  has  the  pisiform  bone 
to  its  inner  side,  and  unciform  bone  to  its  outer  side.  This  sheath  is  completed  behind 
by  the  ligament  which  extends  from  the  pisiform  to  the  unciform  bone,  and  in  front  by  a 
sort  of  annular  ligament.  The  nerve  is  covered  by  a  synovial  membrane  during  its 
passage  through  this  sheath. 

As  soon  as  it  leaves  this  sheath,  the  ulnar  nerve  divides  into  two  terminal  branches, 
the  one  superficial,  and  the  other  deep. 

The  superficial  terminal  branch,  or  trunk  of  the  palmar  collateral  nerves  of  the  fingers,  im- 
mediately gives  off  a  branch  which  passes  beneath  the  flexor  brevis  digiti  minimi,  pene- 
trates the  deep  surface  of  that  muscle,  and  immediately  divides  into  two  other  branches, 
an  internal  and  an  external.  The  internal  is  the  smaller  branch ;  it  crosses  over  the 
muscles  of  the  ball  of  the  little  finger,  beneath  the  palmaris  brevis,  when  it  exists,  gains 
the  inner  side  of  the  anterior  surface  of  the  little  finger,  and  forms  its  internal  palmar  col- 
lateral nerve,  j  The  external  is  larger;  it  sends  a  communicating  twig  to  the  median 
nerve,  and  bifurcates  to  form  the  external  palmar  collateral  nerve  of  the  little  finger,  and  the 
internal  palmar  collateral  nerve  of  the  ring  finger. 

The  deep  terminal  or  muscular  branch  is  somewhat  larger  than  the  superficial  branch 
Immediately  after  its  origin,  it  is  reflected  outward  below  the  unciform  bone,  perforates 
the  flexor  brevis  digiti  minimi,  and  passes  deeply  into  the  palm  of  the  hand,  so  that  it 
cannot  be  exposed  without  dividing  all  the  tendons  of  the  palmar  region. 

This  branch  describes  a  transverse  curve  or  arch  with  the  concavity  directed  upward, 
in  front  of  the  metacarpal  bones,  corresponding  to  and  situated  within  the  curve  de- 
scribed by  the  deep  palmar  arterial  arch,  which  crosses  it  at  an  acute  angle. 

No  branch  arises  from  the  concavity  of  this  nerve,  but  from  its  convexity  a  great  mmi 
her  are  given  off,  in  the  following  order : 

During  the  passage  of  the  nerve  between  the  pisiform  and  unciform  bones,  three  branch- 
es for  the  three  muscles  of  the  hypothenar  eminence. 

Two  very  remarkable  descending  filaments,  which  supply  the  palmar  interossei  of  the 
third  and  fourth  spaces,  and  end  in  the  third  and  fourth  lumhricalcs.  The  first  and  sec- 
ond lumbricales,  and  frequently  the  third  also,  are  supplied  by  the  median  nerve. 

Three  perforating  branches  pass  backward  between  the  upper  ends  of  the  metacarpal 
bones,  give  some  branches  to  the  palmar  interossei,  proceed  along  the  cellular  interval 
between  the  palmar  and  dorsal  interossei,  supply  the  last-mentioned  muscles,  and  termi- 
nate by  anastomosing  with  the  dorsal  collateral  branches  of  the  ulnar  and  radial  nerves. 

We  may  regard  as  terminal  divisions  of  the  deep  branch,  two  branches,  which  are 
given  to  the  two  portions  of  the  adductor  pollicis,t  and  a  branch  for  the  first  dorsal  inter- 
osseous muscle,  from  which  a  filament  is  given  off  that  enters  the  adductor  poUicis  near 
its  lower  border. 

Summary. — From  what  has  been  stated,  it  appears  that  the  ulnar  nerve  gives  off  no 
branch  in  the  arm ;  that  in  the  forearm  it  supplies  some  articular  branches  to  the  elbow- 
joint,  certain  muscular  branches  for  the  flexor  carpi  ulnaris,  and  the  inner  half  of  the 
flexor  profundus,  and  a  cutaneous  filament  which  anastomoses  with  the  internal  cu- 
taneous nerve ;  that  it  gives  off  to  the  hand  a  dorsal  cutaneous  branch,  from  which  the 
dorsal  collateral  nerves  of  the  little  and  ring  fingers,  and  the  internal  dorsal  collateral  of 
the  middle  finger,  proceed ;  a  palmar  cutaneous  division,  which  supplies  the  palmar  collateral 
nerves  of  the  little  finger,  and  the  internal  palmar  collateral  nerve  of  the  ring  finger ;  and 
a  muscular  division,  which  is  distributed  to  the  three  muscles  of  the  hypothenar  emi- 
nence, to  aU  the  interossei,  among  which  we  may  include  the  adductor  poUicis,^  and  to 
the  two  internal  lumbricales. 

*  [This  latter  branch  often  anastomoses  with  the  dorsal  cutaneous  branch  of  the  radial  nerve.] 

t  I  have  observed  that  it  supplies  the  palmaris  brevis,  when  that  muscle  exists. 

i  The  reader  must  here  be  reminded,  that  1  have  regarded  all  that  portiou  of  the  flexor  brevis  pollicis  (of 
authors)  which  is  situated  to  the  inner  side  of  the  tendon  of  the  flexor  longus  pollicis,  or,  in  other  words,  all 
that  portion  which  is  attached  to  the  internal  sesamoid  bone,  as  belonging  to  the  adductor  pollicis.  (See 
Myology,  p.  190.)  The  distribution  of  the  nerves  favours  this  view ;  for  the  flexor  brevis  is  supplied  by 
the  median  nerve,  while  the  two  portions  of  the  adductor  receive  their  nerves  from  the  ulnar.  [This  general 
statement  is  not  quite  correct ;  the  outer  portion  of  the  adductor  (the  inner_head  of  the  flexor  brevis  of  au- 
thors generally)  also  receives  a  small  branch  from  the  median  nerve  (see  p.  787  ;  also  Swan  and  Ellis).] 

*)  It  is  perfectly  rational  to  consider  the  adductor  pollicis  as  the  first  palmar  interosseous  muscle,  which,  fw 
♦hp  sake  of  increased  power  of  adduction,  is  attached  to  the  third  metacarpal  bone. 


MUSCULO-8PIRAL   NERVE.  r^Bfli^ 

..k.  ■        ,..^   ^^%    A ..         Musculo-spiral  JVerve.  i>i-;'*'I. 

The  musculo-spiral  or  radial  nerve,  which  is  the  largest  of  the  terminal  divisions  of  the 
brachial  plexus,  is  intended  for  the  triceps  extensor  cubiti,  for  the  muscles  of  the  pos- 
terior and  external  region  of  the  forearm,  and  for  the  skin  of  the  arm,  the  forearm,  and 
dorsal  region  of  the  hand. 

It  arises  {f,Jig.  286)  from  all  the  five  nerves  of  which  the  brachial  plexus  is  composed, 
by  a  trunk  which  is  common  to  it  and  to  the  circumflex  nerve,  and  it  issues  from  the 
plexus  behind  the  ulnar  nerve,  to  which  it  is  closely  applied.  Immediately  after  its  ori- 
gin, it  passes  downward,  backward,  and  outward  (b,  fig.  288),  in  front  of  the  conjoined 
tendons  of  the  latissimus  dorsi  and  teres  major,  to  gain  the  groove  of  torsion  or  spiral 
groove  of  the  humerus,  into  which  it  enters,  passing  between  the  long  head  of  the  tri- 
ceps and  the  bone,  then  between  the  external  head  and  the  bone  ;  it  traverses  the  whole 
extent  of  this  groove,  and  is  in  relation  with  the  profunda  humeri  artery  and  vein. 
Leaving  this  groove,  opposite  the  junction  of  the  two  upper  thirds  with  the  lower  third 
of  the  humerus,  it  lies  on  the  external  and  anterior  aspect  of  the  arm,  descends  vertical- 
ly between  the  supinator  longus  and  brachialis  anticus,  and  next  between  the  brachialis 
anticus  and  extensor  carpi  radialis  longior,  crosses  the  elbow-joint  (at  b),  passing  in  front 
of  the  outer  condyle  of  the  humerus  and  the  upper  extremity  of  the  radius,  and  then  di- 
vides into  two  terminal  branches. 

Collateral  Branches  of  the  Musculo-spiral  Nerve. 

During  its  winding  and  spiral  course  along  the  arm,  this  nerve  gives  off  a  great  num- 
ber of  collateral  branches  in  the  following  order : 

Branches  given  off  by  the  Musculo-spiral  Nerve  before  it  enters  the  Spiral  Groove. — The 
first  is  the  internal  cutaneous  branch  (/',  fig.  287)  of  the  musculo-spiral,  which  is  sub- 
aponeurotic at  its  commencement,  but  perforates  the  fascia,  becomes  applied  to  the  skin, 
and  divides  into  two  filjiments,  which  pass  obliquely  backward,  and  may  be  traced  as  far 
as  the  olecranon.* 

There  are  several  considerable  branches  to  the  long  head  of  the  triceps  ;  the  highest  of 
which  is  recurrent,  and  may  be  traced  as  far  as  the  scapular  attachments  of  the  muscle. 
A  very  large  descending  branch  may  be  traced  to  the  olecranon. 

There  is  a  branch  for  the  internal  head  of  the  triceps,  one  division  of  which  is  rather 
large,  and  runs  along  the  inner  border  of  the  humerus  in  front  of  the  muscle,  which  it 
does  not  enter  until  it  approaches  the  elbow. 

Branches  given  off  by  the  Musculo-spiral  after  leaving  the  Spiral  Groove. — These  are  the 
external  cutaneous  branch  of  the  musculo-spiral,  a  very  large  branch  which  perforates  the 
muscular  fibres  of  the  triceps  and  the  brachial  aponeurosis,  then  lies  in  immediate  con- 
tact with  the  skin  of  the  external  region  of  the  arm,  passes  obliquely  backward,  and  di- 
vides into  a  great  number  of  filaments,  which  supply  the  skin  of  the  posterior  region  of 
the  forearm,  and  may  be  traced  down  to  the  carpus. 

The  branch  for  the  external  head  of  the  triceps  and  for  the  anconeus,  which  is  remarkable 
for  its  length,  descends  vertically  between  the  external  and  long  heads  of  the  triceps, 
supplies  the  former  of  these,  enters  the  anconeus,  and  may  be  traced  as  far  as  the  lower 
part  of  that  muscle. 

All  these  branches  are  remarkable  for  being  given  off  at  nearly  the  same  height ;  that 
is  to  say,  near  the  shoulder-joint,  and  for  accompanying  the  trunk  of  the  musculo-spiral 
nerve. 

Branches  given  off  by  the  Musculo-spiral  Nerve  in  the  Forearm. — These  are  the  branches 
for  the  supinator  longus,  and  those  for  the  extensor  carpi  radialis  longior,  which  enter  the 
inner  surface  of  the  upper  part  of  those  muscles. 

Terminal  Branches  of  the  Musculo-spiral  Nerve. 

Reduced  to  one  half,  or  less,  of  its  original  size,  by  the  successive  emission  of  the  pre- 
ceding branches,  the  musculo-spiral  or  radial  nerve  divides  in  front  of  the  elbow  (b,  fig. 
388)  into  two  unequal  branches,  the  one  deep  or  muscular,  the  other  superficial  or  digital. 

The  deep  or  muscular  division  of  the  musculo-spiral  nerve,  or  the  posterior  interosseous, 
is  larger  than  the  superficial  division  ;  it  immediately  gives  off  a  branch  which  passes 
vertically  in  front  of  the  extensor  carpi  radialis  brevier,  and  soon  dips  into  that  muscle  ; 
the  nerve  then  becomes  flattened,  perforates  the  supinator  brevis,  and  pursues  a  very 
oblique  and  spiral  course  around  the  radius  and  within  that  muscle,  to  which  it  gives 
branches  {branches  for  the  supinator  brevis) :  it  then  emerges  from  the  posterior  aspect  of 
this  muscle,  and  immediately  divides  into  a  great  number  of  diverging  branches,  some 
of  which  are  intended  for  the  superficial,  and  the  others  for  the  deep  layer  of  muscles  on 
the  posterior  region  of  the  forearm. 

The  branches  given  to  the  superficial  layer  are,  those  for  the  extensor  communis  digt- 
torum,  which  are  very  numerous  and  diverging,  the  superior  being  also  recurrent;  the 
branch  for  the  extensor  proprius  digiti  minimi ;  and  the  branch  for  the  extensor  carpi  lU- 
*  [Anastomosing  with  the  accessory  of  the  internal  cutaneous.) 


792 


NEUROLOGY. 


naris :  all  these  branches  arise  by  a  common  trunk,  and  enter  the  deep  surface  of  the 
muscles. 

The  branches  for  the  deep  layer  also  arise  by  a  common  trunk  (i,  Jig.  289),  whicli  may  be 
Fig.  289.  regarded  as  the  continuation  of  the  muscular  division  of  the  mus- 

culo-spiral,  considerably  diminished  in  size.  This  common  trunk 
passes  vertically  downward  between  the  superficial  and  deep  lay- 
ers of  muscles,  gives  off  a  branch,  which  enters  the  superficial  as- 
pect of  the  extensor  longus  ■pollicis,  then  passes  between  the  adduc- 
tor longus  and  extensor  brevis  pollicis  on  the  one  hand,  and  the 
extensor  longus  pollicis  on  the  other,  runs  in  contact  with  the  inter- 
im/, osseous  ligament,  and  gives  off  a  first  branch  to  the  extensor  lon- 
gus pollicis,  a  second  which  enters  the  deep  surface  of  the  same 
muscle,  and  a  small  branch  which  enters  the  outer  border  of  the 
entensor  proprius  indicis. 

Reduced  at  length  to  a  very  small  branch,  the  muscular  division 
of  the  musculo-spiral  nerve  enters  the  groove  (at  s)  for  the  tendons 
of  the  extensor  communis  digitorum,  lying  beneath  them,  in  con- 
tact with  the  periosteum ;  it  runs  over  the  carpus,  and  expands  into 
a  number  of  articular  fdaments,  which  enter  the  radio-carpal,  carpal, 
and  carpo-metacarpal  articulations ;  in  this  latter  portion  of  its 
course,  the  nerve  is  of  a  grayish  colour,  swollen,  and,  as  it  were, 
knotted ;  a  condition  which  is  observed  in  all  articular  nerves. 

The  superficial,  cutaneous,  or  digital  division  of  the  musculo-spiral 
nerve,  or  the  radial  nerve  properly  so  called,  forms  the  external  dor 
sal  nerve  of  the  hand,  and  is  about  half  the  size  of  the  muscular  di- 
vision.    It  passes  vertically  downward,  between  the  supinator  lon- 
gus and  the  extensor  carpi  radialis  longior,  along  the  outer  side  of 
the  radial  artery  :  having  reached  the  middle  of  the  forearm,  it  es- 
capes from  beneath  the  tendon  of  the  supinator  longus,  and  runs 
along  the  outer  border  of  that  tendon. 
Situated  at  first  beneath  the  fascia,  it  soon  perforates  it,  becomes  sub-cutaneous,  runs 
vertically  downward,  and,  about  an  inch  and  a  half  above  the  styloid  process  of  the  radius, 
divides  into  an  external  and  an  internal  branch. 

The  external  branch  (o,  figs.  288,  289),  which  is  the  smaller,  runs  along  the  outer  side 
of  the  styloid  process  of  the  radius,  and  then  along  the  outer  border  of  the  carpus,*  of 
the  first  metacarpal  bone,  and  of  the  first  and  second  phalanges  of  the  thumb,  and  termi- 
nates in  the  skin  beneath  the  nail ;  it  is  the  external  dorsal  collateral  branch  of  the  thumb. 
The  internal  branch  (e,  fig.  289),  which  is  much  larger,  passes  obliquely  behind  the  ra- 
dius, crosses  the  tendons  of  the  adductor  longus  and  extensor  brevis  pollicis,  and  divides 
into  three  secondary  branches,  namely,  counting  from  without  inward,  the  internal  dor- 
sal collateral  nerve  of  the  thumb,  and  the  external  and  internal  dorsal  collateral  nerves  of  thf 
index  finger,  t 

Summary. — The  musculo-spiral  nerve  gives  off,  in  the  arm.,  two  cutaneous  branches, 
one  internal,  the  other  external,  the  latter  of  which  is  much  the  larger,  and  may  be  tra- 
ced as  far  as  the  carpus  ;  and  also  muscular  branches  to  the  three  portions  of  the  triceps 
and  to  the  anconeus :  to  the  forearm,  it  supplies  muscular  branches  to  all  the  muscles  of 
the  deep  and  superficial  layers  of  the  posterior  and  external  regions ;  and  to  the  hand, 
certain  cutaneous  branches,  namely,  the  dorsal  collateral  nerves  of  the  thumb  and  index 
finger. 

General  Summary  of  the  Distribution  of  the  Jferves  of  the  Brachial  Plexus. 

The  preceding  description  shows  that  the  brachial  plexus  supplies  the  skin,  the  mus- 
cles, and  the  articulations  of  the  upper  extremity,  including  the  shoulder.  We  shall 
briefly  recapitulate,  first  the  muscular  and  then  the  cutaneous  branches. 

The  Muscular  Branches. — By  its  collateral  branches,  the  brachial  plexus  supplies  the 
scaleni  and  all  the  muscles  which  move  the  shoulder,  excepting  the  trapezius,  which 
receives  its  nerves  from  the  brachial  plexus  and  from  the  spinal  accessory  nerve  of  Wil- 
lis ;  by  its  terminal  branches  it  supplies  all  the  muscles  of  the  arm,  the  forearm,  and  the 
hand. 

Each  of  the  muscles  which  move  the  shoulder  receive  a  special  nerve  ;  thus,  besides  the 
nervous  filaments  for  the  scaleni,  there  is  the  nerve  for  the  sub-clavius  ;  the  nerve  for 
the  levator  anguU  scapulae  ;  the  nerves  for  the  rhomboideus  ;  the  nerve  for  the  serratua 
magnus,  which  is  better  known  as  the  external  thoracic  nerve  ;  the  nerve  for  the  latis- 
simus  dorsi,  which  is  generally  described  as  a  branch  of  the  sub-scapular ;  and  the  nerves 
for  the  pectoralis  major  and  minor. 

The  muscles  which  move  the  arm  upon  the  shoulder  also  receive  their  nerves  from  the 

*  [NVhere  it  sends  an  anastomotic  filament  to  the  palmar  cutaneous  branch  of  the  median.  J 
t  [It  also  supplies  the  external  dorsal  collateral  of  the  middle  finger,  and  often  unites  with  tlie  ulnar  cuta- 
oeius,  to  form  the  dorsal  collaterals  for  the  contiguous  sides  of  the  middle  and  ring  fingers.] 


THE  NERVES  OF  THE  BRACHIAL  PLEXUS.  793 

brachial  plexus  ;  sometimes  there  is  a  separate  nerve  for  each  muscle,  sometimes  the 
same  nerve  supplies  two  muscles.  The  nerve  for  the  deltoid,  or  the  circumflex  nerve, 
also  supplies  the  teres  minor.  The  supra-spinatus  and  infra-spinatus  receive  their  fila- 
ments from  the  same  branch,  viz.,  the  supra-scapulum  nerve.  The  teres  major  receives 
a  branch  from  the  sub-scapular  nerve.* 

Of  the  muscles  which  move  the  forearm  upon  the  arm.  Those  of  the  anterior  region,  oi 
the  flexors,  viz.,  the  biceps,  coraco-brachialis,  and  brachialis  anticus,  receive  their  fila- 
ments from  the  musculo-cutaneous  nerve  ;  the  muscle  of  the  posterior  region,  the  tri- 
ceps, is  supplied  entii  ely  by  the  musculo-spiral  nerve.  The  ulnar  nerve  gives  no  branch 
in  the  arm. 

The  muscles  which  move  the  radius  upon  the  ulna,  and  those  which  move  the  hand  and  the 
fingers,  are  thus  supplied.  The  interosseous  division  of  the  musculo-spiral  nerve  sup- 
plies the  muscles  of  the  posterior  region  of  the  forearm,  viz.,  in  the  superficial  layer,  the 
common  extensor,  the  extensor  proprius  digiti  minimi,  and  the  extensor  carpi  ulnaris ; 
in  the  deep  layer,  the  supinator  brevis,  the  adductor  longus,  extensor  brevis,  and  extensor 
longus  pollicis,  and  the  extensor  proprius  indicis. 

The  muscles  of  the  exterior  region  of  the  forearm,  namely,  the  two  supinators,  and  the 
two  radial  extensors  of  the  carpus,  also  receive  their  branches  from  the  musculo-spiral 
nerve. 

The  muscles  of  the  anterior  region  of  the  forearm  receive  their  filaments  from  the  median 
nerve,  excepting  the  flexor  carpi  ulnaris  and  the  internal  half  of  the  flexor  profundus, 
which  are  supplied  by  the  ulnar  nerve.  The  flexor  profundus,  then,  by  a  peculiarity 
which  not  unfrequently  occurs  in  regard  to  compound  muscles,  receives  its  nerves  from 
two  different  sources. 

The  intrinsic  muscles  of  the  hand  are  supplied  in  the  following  manner  :  Those  of  the 
ball  of  the  thumb  by  the  median  nerve  ;  those  of  the  ball  of  the  little  finger  by  the  ulnar 
nerve  ;  the  two  external  lumbricales  by  the  median  nerve  ;  the  two  internal  lumbricales 
by  the  ulnar  nerve  ;  all  the  interossei,  including  the  adductor  pollicis,  by  the  ulnar  nerve. 

The  Cutaneous  Branches  A — The  skin  which  covers  the  shoulder  on  the  outer  side  re- 
ceives its  nerves  from  the  cervical  plexus. 

The  skin  of  the  external  surface  of  the  arm  receives  its  nerves  from  the  cutaneoiis 
branches  of  the  circumflex  nerve,  and  from  the  external  cutaneous  branch  of  the  mus- 
culo-spiral. The  skin  of  the  anterior  and  internal  regions  of  the  arm  receives  its  nerves 
from  the  internal  cutaneous  branch  of  the  musculo-spiral,  from  the  accessory  nerve  of 
the  internal  cutaneous,  which  anastomoses  with  the  second  intercostal,  from  a  small 
branch  of  the  internal  cutaneous,  and  from  the  humeral  branch  of  the  third  intercostal. 

The  skin  of  the  forearm  receives  its  filaments  from  the  internal  cutaneous,  which 
anastomoses  with  the  cutaneous  filaments  of  the  musculo-spiral,  ulnar,  and  musculo-cu- 
taneous nerves. 

The  skin  of  the  dorsal  region  of  the  hand  and  of  the  fingers  receives  its  filaments  from 
the  dorsal  branches  of  the  radial  nerve,  in  the  two  external  thirds  of  that  region,  and 
from  the  dorsal  branch  of  the  ulnar  nerve  in  the  internal  third. 

The  skin  of  the  palmar  region  of  the  hand  and  fingers  receives  its  filaments  from  the 
median  nerve  in  the  two  external  thirds,  and  from  the  ulnar  in  the  internal  third,  or,  to 
speak  more  precisely,  the  median  nerve  supplies  the  external  and  internal  collateral 
branches  of  the  thumb,  the  index,  and  the  middle  fingers,  and  the  external  collateral 
nerve  of  the  ring  finger ;  the  ulnar  nerve  supplies  the  external  and  internal  collateral 
nerves  of  the  little  finger,  and  the  internal  collateral  branch  of  the  ring  finger. 

Some  of  the  terminal  branches  of  the  median  nerve,  and  the  terminal  divisions  of  the 
internal  cutaneous  and  musculo-cutaneous,  are  lost  in  the  skin  of  the  upper  part  of  the 
palm  of  the  hand. 

The  palmar  collateral  nerves  of  the  fingers  offer  the  following  peculiarities :  the 
branches  which  they  give  to  the  skin  are  placed  either  opposite  to  each  other,  or  alter- 
nately ;  each  of  these  branches  tenninates  separately  in  a  pencil  of  filaments  ;  the  twigs 
from  the  internal  branches  do  not  anastomose  with  those  from  the  external ;  lastly,  the 
terminal  extremities  of  the  external  and  internal  collateral  branches  do  not  anastomose 
with  each  other  in  the  pulp  of  the  finger,  but  expand  separately,  and  are  distributed  to 
the  skin  of  the  pulp  and  to  the  skin  under  the  nail. 

The  branches  which  supply  the  palmar  aspect  of  the  fingers  present  a  very  remark- 
able condition,t  consisting  in  the  presence  of  small,  grayish,  gangliform  bodies,  always 
of  a  crescentic  form.     These  bodies  are  very  numerous  ;  they  are  sometimes  separate, 

*  The  teres  minor  and  the  infra-spinatus  are,  therefore,  supplied  by  two  different  branches,  which  would 
induce  us  to  describe  these  muscles  separately,  did  we  not  see  that  compound,  and  sometimes  even  simpla 
muscles  receivo-two  or  more  distinct  nerves.- 

t  A  beautiful  preparation  of  the  cutaneous  nerves  of  the  upper  extremity  may  be  made  by  removing  Ihs 
skin,  either  by  turning  it  inside  out,  in  the  same  way  as  an  eel  is  skinned,  or  by  making  a  longitudinal  incision 
along  the  outer  side  of  the  limb.  In  both  cases  the  fascia  should  be  removed  with  the  skin.  In  the  first  meth- 
od, by  which  a  very  fine  preparation  may  be  made,  the  everted  skin  represents  a  kind  of  glove,  the  inner  sui- 
face  of  which  is  formed  by  tlie  epidermis,  and  the  outer  by  the  deep  surface  of  the  skin 

X  This  was  pointed  out  in  one  of  the  last  concours  of  tlie  assistants  (aides)  of  the  Faculty,  by  M.M.  AndjaJ, 
ramus,  and  Lacroix,  who  had  to  dissect  the  cutaneous  nerves  of  the  hand. 

5  H 


704  NEUROLOGY. 

and  sometimes  arranged  in  groups  ;  they  do  not  essentially  belong  to  the  nerves,  but  are 
applied  to  them,  and  may  be  separated  from  them  by  slight  force.  They  are,  therefore, 
not  ganglia. 

If  we  consider  that  these  gangliform  bodies  occupy  the  palmar  region  only,  and  are 
never  found  in  the  dorsal  region,  that  they  exist  in  the  sole  of  the  foot  as  well  as  in  the 
palm  of  the  hand,  that  they  have  been  found  upon  the  nerves  which  surround  the  artic- 
ulations, and,  consequently,  upon  nerves  which  are  subject  to  constant  pressure,  that  I 
have  even  found  them  upon  an  intercostal  nerve  which  was  reflected  over  the  side  of 
the  sternum,  and,  lastly,  that  they  do  not  exist  in  the  infant  at  birth,  and  are  more  numer- 
ous in  proportion  as  the  palm  of  the  hand  is  more  callous  we  shall  be  warranted  in  con- 
cluding that  they  are  the  result  of  external  pressure. 


THE  ANTERIOR  BRANCHES  OF  THE  DORSAL  NERVES,  OR  THE  INTER- 
COSTAL NERVES. 

Dissection. — Enumeration. — Common  Characters. — Characters  proper  to  each. 

Dissection. — Search  carefully  for  the  cutaneous  branches,  some  of  which  are  to  be 
found  opposite  the  sides  of  the  sternum,  and  others  about  the  middle  of  the  intercostal 
spaces.  Saw  through  the  sternum  in  the  median  line,  and  open  the  abdomen  through 
the  linea  alba.  Sacrifice  one  half  of  the  thorax,  or,  rather,  break  the  ribs  through  the 
middle,  so  as  to  trace  the  nerves  from  within  outward. 

The  anterior  branches  of  the  dorsal  nerves,  twelve  in  number,  are  intended  for  the  parietes 
of  the  thorax  and  abdomen.* 

These  branches  offer  at  once  a  great  uniformity,  and  a  great  simplicity  in  their  distri- 
bution. I  shall  first  explain  their  common  characters,  and  shall  then  notice  the  pecu- 
liarities Dresented  by  each. 

Common  Characters. 

The  anterior  branches  of  the  dorsal  nerves,  or  the  intercostal  nerves,  separated  from  the 
posterior  branches  by  the  superior  costo-transverse  ligament,  appear  like  flattened  cords, 
which  pass  to  the  middle  of  the  corresponding  intercostal  space  (see^lf^.  268) ;  there  they 
are  situated  between  the  pleura  and  the  aponeurosis,  which  is  continuous  with  the  in- 
ternal intercostal  muscle.  After  proceeding  for  a  certain  distance,  they  pass  between 
the  external  and  internal  intercostal  muscles,  and  approach  the  groove  of  the  rib  above, 
but  they  are  not  lodged  in  it,  for  they  always  lie  below  the  intercostal  vessels. 

At  about  the  same  situation  in  each  space,  that  is  to  say,  about  half  way  between  the 
vertebral  column  and  the  sternum,  the  intercostal  nerves  divide  into  two  branches,  the 
one  intercostal,  and  the  other  perforating  or  cutaneous. 

The  intercostal  branch  is  the  continuation  of  the  trunk  of  the  nerve,  and  is  distinguish- 
ed from  it  only  by  its  smaller  size.  It  runs  along  the  lower  border  of  the  rib  above,  and 
then  that  of  the  corresponding  costal  cartilage ;  it  is  sometimes  situated  on  the  internal 
surface  of  the  cartilage,  and  having  reached  the  forepart  of  the  intercostal  space,  it  per- 
forates this  space  from  behind  forward,  runs  along  the  sternum,  is  inclined  somewhat 
inward  over  that  bone,  and  is  then  reflected  outward,  between  the  pectoralis  major  and 
the  skin,  to  which  latter  it  is  distributed.  These  small  filaments  may  be  called  the  an- 
terior perforating  filaments.  During  its  course,  the  intercostal  nerve  and  its  continua- 
tion give  off  a  great  number  of  nervous  filaments.  Not  unfrequently  the  intercostal 
nerve  gives  off,  in  the  back  part  of  the  space,  a  small  branch,  which  reaches  the  upper 
border  of  the  rib  below.  When  this  branch  does  not  exist,  its  place  is  supplied  by  sev- 
eral twigs  which  have  a  similar  distribution,  some  of  which  even  pass  to  the  intercostal 
space  below,  crossing  obliquely  over  the  internal  surface  of  the  rib.  In  like  manner,  we 
sometimes  find  some  small  twigs  proceeding  from  the  upper  side  of  the  nerve  over  the 
internal  surface  of  the  rib  above,  and  reaching  the  next  intercostal  space.  Lastly,  from 
the  lower  side  of  the  intercostal  nerve  and  its  continuation  a  series  of  twigs  are  given 
off,  which  divide  into  filaments  that  curve  towards  each  other  so  as  to  form  arches  or 
loops,  from  which  the  terminal  filaments  proceed.  In  no  part  of  the  body  are  there  found 
longer  or  more  delicate  nervous  filaments  ;  some  of  them  run  through  half  the  length  of 
an  intercostal  space  without  diminishing  in  size,  and  several  evidently  belong  to  the 
periosteum. 

The  perforating  or  cutaneous  branches  are  often  larger  than  the  intercostal  branches  ; 
they  pass  very  obliquely  through  the  external  intercostal  muscles,  and  after  running  for 
a  certain  distance  between  those  muscles  and  the  serratus  magnus,  each  of  them  divides 
into  two  smaller  branches,  the  one  anterior,  and  the  other  posterior  or  reflected :  the  an- 
terior branches  run  horizontally  forward,  become  sub-cutaneous  by  escaping  between  the 
digitations  of  the  serratus  magnus  in  the  eight  superior  intercostal  spaces,  and  between 
the  digitations  of  the  obliquus  externus  abdominis  in  the  four  lower  spaces,  and  then, 

*  Haller  only  admits  eleven  dorsal  nerves,  because  he  considers,  and  not  without  reason,  the  twelfth  as  a 
Inmbar  nerve. " 


ANTERIOR    BRANCHES    OF    THE    DORSAL    NERVES.  795 

becoming  applied  to  the  skin,  spread  into  a  number  of  filaments,  which  almost  always 
anastomose  with  the  adjacent  filaments  of  the  nerves  above  and  below. 

The  posterior  or  reflected  branches  immediately  perforate  the  serratus  magnus  and  the 
obliquus  externus  abdominis,  are  reflected  upon  themselves,  pass  backward  between 
the  latissimus  dorsi  and  the  skin,  and  after  running  horizontally  for  a  distance  of  one  .or 
two  inches,  are  again  reflected  forward,  and  are  then  lost  in  the  skin. 

Proper  Characters  of  each  of  the  Anterior  Branches  of  the  Dorsal  J^erves. 

The  First  Dorsal  Nerve. — This  nerve  belongs  to  the  brachial  plexus,  into  which  it  en- 
ters immediately  after  its  escape  from  the  inter-vertebral  foramen,  crossing  over  the  neck 
of  the  first  rib  at  an  acute  angle.  P'rom  its  size,  it  resembles  the  lower  cervical  nerves, 
and  diflfers  widely  from  the  remaining  dorsal  nerves.  It  becomes  intercostal  only  by 
giving  off  a  small  intercostal  twig  at  its  exit  from  the  inter- vertebral  foramen.  This  in- 
tercostal branch  is  applied  to  the  under  surface  of  the  first  rib,  which  it  crosses  obliquely 
from  behind  forward,  so  that  it  does  not  reach  the  first  intercostal  space  until  opposite 
the  junction  of  the  rib  with  its  cartilage  ;  it  gains  the  middle  of  this  space  near  the  ster- 
num, at  which  point  it  passes  forward  through  the  space,  like  the  other  intercostal 
nerves,  and  ramifies  in  the  muscles  and  the  skin. 

The  Second  Dorsal  Nene. — This  nerve  crosses  obliquely  over  the  second  rib,  on  the 
outer  side  of  its  neck,  to  reach  the  first  intercostal  space,  and  then  recrosses  the  same 
rib,  about  its  middle,  to  gain  the  second  intercostal  space,  where  it  divides  into  two 
branches  :  the  intercostal,  which  follows  the  lower  border  of  the  second  rib,  and  presents 
nothing  remarkable ;  and  the  -perforating  or  cutaneous  branch,  which  requires  a  special 
description. 

The  perforating  or  cutaneous  branch,  which  is  destined  exclusively  for  the  skin  of  the 
arm,  is  much  larger  than  the  other  branches  of  the  same  kind.  It  emerges  from  the 
thorax  at  the  middle  of  the  second  intercostal  space,  immediately  below  the  second  rib, 
passes  directly  through  that  space,  is  reflected  at  right  angles  over  an  aponeurotic  arch, 
runs  outward,  and  immediately  subdivides  into  two  branches  of  equal  size,  the  one  ex- 
ternal  and  the  other  internal. 

The  external  or  intercosto-humeral  branch  (to  the  left  of  d,  fig.  287)  traverses  the  axilla, 
receives  an  anastomotic  twig  from  the  accessory  nerve  (c)  of  the  internal  cutaneous  of 
the  ann,  reaches  and  crosses  over  the  outer  border  of  the  latissimus  dorsi,  and  divides 
into  two  cutaneous  filaments,  one  of  which  is  distributed  to  the  skin  of  the  posterior  re- 
gion of  the  arm,  while  the  other  lies  in  contact  with  the  skin  of  the  internal  region  of  the 
arm,  runs  parallel  to  the  accessory  nerve  of  the  internal  cutaneous,  and  may  be  traced 
as  low  down  as  the  elbow. 

The  internal  branch  crosses  the  outer  border  of  the  latissimus  dorsi,  lower  down  than 
the  preceding  branch,  becomes  applied  to  the  skin,  and  divides  into  internal  and  posterior 
filaments,  which  are  lost  in  the  skin  of  the  arm. 

The  perforating  branch,  therefore,  of  the  second  dorsal  nerve  completes  the  system 
of  cutaneous  nerves  of  the  arm. 

The  third  dorsal  nerve  is  precisely  similar  to  the  others,  excepting  in  its  perforating, 
cutaneous,  or  intercosto-humeral  branch,  which  is  distributed  to  the  integuments  both  of 
the  thorax  and  arm.  It  is  much  smaller  than  the  preceding ;  it  emerges  (d,fig.  287)  from 
between  the  digitations  of  the  serratus  magnus,  is  reflected  backward  upon  itself,  gives 
a  small  branch  to  the  mamma,  crosses  the  outer  border  of  the  latissimus  dorsi,  below  the 
perforating  branch  of  the  preceding  nerve,  and  having  reached  the  upper  part  of  the 
shoulder,  is  reflected  upon  itself,  describing  a  curve  with  the  concavity  turned  upward, 
and  terminates  in  the  skin  of  the  inner  and  upper  part  of  the  arm. 

The  fourth,  fifth,  sixth,  and  seventh  dorsal  nerves  agree  exactly  with  the  general  descrip- 
tion. The  intercostal  muscles,  the  triangularis  stemi,  the  serratus  magnus,  the  obli- 
quus externus  abdominis,  the  upper  part  of  the  recti  abdominis,  and  the  integuments  of 
the  thorax,  are  supplied  with  nerves  from  these  branches,  in  the  order  and  manner  al- 
ready pointed  out.  I  would  direct  attention  to  the  considerable  number  of  filaments  dis- 
tributed to  the  skin  of  the  mamma  in  the  female.  The  perforating  branches  of  the  fourth 
and  fifth  dorsal  nerves  each  give  a  branch  to  the  mamma,  and  a  posterior  branch,  which 
crosses  the  latissimus  dorsi,  and  is  distributed  to  the  skin  over  the  scapula ;  the  skin  of 
the  mamma  receives  nerves  from  the  third,  fourth,  and  fifth  dorsal  nerves. 

The  eighth,  ninth,  tenth,  and  eleventh  dorsal  nerves  belong  to  the  intercostal  spaces  form- 
ed by  the  false  ribs :  they  leave  those  spaces  at  the  point  where  the  costal  cartilages 
change  their  direction  to  bend  upward  ;  they  perforate  the  costal  attachments  of  the  di- 
aphragm, without  giving  that  muscle  any  filaments,  continue  their  oblique  course  in  the 
substance  of  the  parietes  of  the  abdomen,  for  which  they  are  destined,  and  are  distribu- 
ted to  these  parts,  in  the  same  way  as  the  nerves  in  the  intercostal  spaces,  with  some 
slight  modifications.  Thus,  the  perforating  branches  perforate  the  external  intercostals 
and  the  obliquus  externus  abdominis  in  the  same  line  as  the  perforating  branches  of  the 
preceding  nerves ;  the  intercostal  branches,  properly  so  called,  having  thus  become  ab- 
dormnal,  run  between  the  external  and  internal  oblique  muscles,  just  as,  in  the  upper  spa- 


fBi  NEUROLOGY. 

ces,  they  ran  between  the  external  and  internal  intercostals.  Having  reached  the  rec- 
tus abdominis,  they  give  off  a  cutanemis  or  perforating  branch,  and  then  enter  the  sheath 
of  that  muscle,  through  certain  openings  at  its  outer  border,  and  proceed  between  the 
muscle  and  the  posterior  layer  of  the  sheath  :  at  the  junction  of  the  two  external  thirds 
with  the  internal  third  of  the  rectus,  these  branches  pass  through  it  very  obliquely  to- 
wards the  middle  line,  and  divide  into  muscular  filaments,  which  are  lost  in  the  muscle, 
and  the  lowest  of  wliich  pass  vertically  downward,  and  cutaneous  filaments,  which  per- 
forate the  anterior  layer  of  the  sheath  of  the  rectus,  on  each  side  of  the  linea  alba,  but 
not  always  at  the  same  distance  from  it,  and  are  reflected  horizontally  outward  in  the 
sub-cutaneous  cellular  tissue  lying  immediately  in  contact  with  the  skin. 

The  twelfth  dorsal  nerve  {d,  fig.  290)  might,  according  to  the  opinion  of  Haller,  be  re- 
garded as  the  first  lumbar  nerve.  It  is  larger  than  the  other  dorsal  nerves  ;  it  emerges 
from  the  vertebral  canal  between  the  last  rib  and  the  first  lumbar  vertebra,  passes  in 
front  of  the  costal  attachments  of  the  quadratus  lumborum,  runs  along  the  lower  border 
of  the  twelfth  rib,  proceeds  very  obliquely  downward,  like  that  rib,  perforates  the  apo- 
neurosis of  the  transversalis  muscle,  and,  like  the  preceding  nerves,  divides  almost  im- 
mediately into  two  branches.  The  abdominal  branch,  which  corresponds  to  the  inter- 
costal branch  of  the  other  nerves,  passes  horizontally  forward  between  the  transversalis 
and  obUquus  internus,  supplying  those  muscles,  and  almost  always  gives  off,  below,  an 
anastomotic  branch  to  the  abdominal  or  ilio-inguinal  branch  of  the  lumbar  plexus,  and 
then  penetrates  the  sheath  of  the  rectus,  where  it  is  arranged  like  the  preceding  nerves. 

The  perforating  or  cutaneous  branch  is  remarkable  for  being  larger  than  the  abdominal 
branch,  and  for  its  distribution  ;  it  perforates  very  obliquely,  and  at  the  same  time  gives 
branches  to  the  external  and  internal  oblique  muscles,  becomes  sub-cutaneous,  passes 
vertically  downward,  crosses  at  right  angles  over  the  crest  of  the  ilium,  and  divides  into 
anterior,  posterior,  and  middle  branches,  which  are  distributed  to  the  skin  of  the  gluteal 
region. 

Not  unfrequently  this  gluteal  cutaneous  branch  is  given  off  by  the  first  lumbar  nerve, 
and  then  the  cutaneous  branch  of  the  twelfth  dorsal  nerve  is  arranged  like  those  of  the 
preceding  nerves,  and  ramifies  in  the  skin  between  the  last  rib  and  the  crest  of  the  ili- 
um. There  is  a  mutual  relationship  between  the  twelfth  dorsal  and  the  first  lumbar 
nerves,  so  that  they  are  often  inversely  developed  ;  they  always  communicate  with  each 
other  by  a  branch  called  the  dorsi-lumbar,  but  the  mode  and  place  of  communicati»n  are 
subject  to  many  varieties  :  thus,  it  is  sometimes  effected  by  a  winding  branch  which 
runs  along  the  outer  border  of  the  quadratus  lumborum,  at  other  times  it  takes  place  in 
the  substance  of  the  abdominal  muscles.* 

Summary  of  the  Dorsal  or  Intercostal  JVerves, 

These  nerves  are  distributed  to  the  parietes  both  of  the  thorax  and  the  abdomen,  which 
in  all  respects 'may  be  regarded  as  constituting  a  single  cavity,  the  thoracico-abdominal. 
The  muscular  and  cutaneous  thoracic  branches  from  the  brachial  plexus,  some  small 
branches  derived  from  the  lumbar  plexus,  and  the  posterior  spinal  branches  of  the  dorsal 
nerves,  complete  the  nervous  system  of  the  thoracic  and  abdominal  parietes. 

The  dorsal  nerves  are  divided  into  muscular  nerves,  for  the  muscles  of  the  thoracico- 
abdominal  parietes,  and  for  the  muscles  which  lie  upon  them,  and  into  cutaneous  nerves. 
To  obtain  a  good  idea  of  the  latter,  they  should  all  be  displayed  in  the  same  preparation. 
Several  rows  of  parallel  cutaneous  filaments  will  then  be  seen,  in  the  following  order, 
proceeding  from  before  backward. 

The  anterior  perforating  or  cutaneous  nerves,  which  are  extremely  small,  emerge  at  the 
sides  of  the  sternum  and  of  the  linea  alba,  and  are  reflected  forward. 

The  perforating  or  cutaneous  nerves,  which  might  be  called  middle,  divide  into  orie  set 
of  branches,  which  run  parallel  to  each  other  forward,  towards  the  sternum,  and  another 
set,  also  parallel,  which  run  backward,  towards  the  vertebral  column. 

We  have  elsewhere  stated  that  other  posterior  cutaneous  branches  are  gren  off  from 
the  posterior  branches  of  the  dorsal  nerves.  They  are  parallel,  and  run  outward,  and 
may  be  traced  as  far  as  on  a  level  with  the  axilla. 


THE  ANTERIOR  BRANCHES  OF  THE  LUMBAR  NERVES. 

Enumeration. — The  Lumbar  Plexus — Collateral  Branches,  Abdominal  and  Inguinal. — Ter- 
minal Branches — the  Obturator  Nerve — the  Crural  Nerve  and  its  Branches,  viz.,  the  Mus- 
culo-c^ttaneous — the  Accessory  of  the  Internal  Saphenous — the  Branch  to  the  Sheath  of  the 
Vessels — the  Muscular  Branches — the  Internal  Saphenous. 

Dissection. — In  order  to  see  these  nerves  at  their  exit  from  the  inter-vertebral  forami- 
na, and  also  to  obtain  a  view  of  the  lumbar  plexus,  it  is  necessary  carefully  to  divide  the 

*  In  a  subject  which  had  a  thirteenth  or  lumbar  rib,  there  was  a  tTiirteenth  dorsal  nerve,  of  large  size, 
which  crossed  the  supernumerary  rib,  and  which  corresponded  in  its  distribution  with  both  the  twelfth  dorsal 
and  the  first  lumbar  nerves  ;  it  only  communicated  with  the  first  lumbar  nerve  by  a  very  small  filament ;  it 
gave  off  a  deep  perforating  or  cutaneous  branch  to  the  gluteal  region,  and  also  an  ilio-scrolal  branch.  In  thia 
•abject  there  were  only  four  lumbar  nerves. 


THE    LUMBAR    PLEXUS. 


797 


psoas  muscle,  m  which  they  are  situated ;  the  branches  which  emerge  from  the  plexus 
must  be  dissected  with  the  greatest  care  as  they  are  passing  under  the  femoral  arch, 
and  then  to  their  final  distribution. 

The  anterior  branches  of  the  lumbar  nerves  (21  to  25,  fig.  268)  are  five  in  number,  and 
are  distinguished  as  the  first,  second,  third,  fourth,  and  fifth  :  they  gradually  increase  in 
size  from  the  first  to  the  fifth,  and  form  a  continuation  of  the  series  of  anterior  branches 
of  the  dorsal  nerves  :  after  having  given  off  one  or  two  branches  to  the  lumbar  ganglia 
(tt)  of  the  sympathetic,  and  some  branches  to  the  psoas  muscle,  they  end  by  anastomo- 
sing so  as  to  form  the  lumbar  plexus  (Z). 

The  anterior  branch  of  the  first  lumbar  nerve  (1  I,  fig-  290)  is  the  smallest  of  all,  and  ia 
almost  equal  in  size  to  the  anterior  branch  of  the  Fig-.  290. 

twelfth  dorsal  nerve  ;  immediately  after  emerging 
from  the  inter-vertebral  foramen,  it  divides  into 
three  unequal  branches  ;  two  of  these  (a  and  above 
b)  are  external  and  oblique,  and  constitute  the  ab- 
dmninal  branches  {ilio-scrotal  nerves  of  some  authors) ; 
the  third  is  internal,  vertical,  and  often  very  small ; 
it  is  the  anastomotic  branch  which  joins  the  second 
nerve. 

The  anterior  branch  of  the  second  lumbar  nerve  is  at 
least  twice  as  large  as  the  preceding ;  it  passes  al- 
most vertically  downward,  and  gives  off  an  anterior 
branch,  the  internal  inguinal  (genito-crural  of  Bichat, 
b),  and  an  external  branch,  the  external  inguinal  {in- 
guino-cutaneous  of  Chaussier,  c).  It  is  scarcely  di- 
minished in  size  by  giving  oif  these  nerves,  but  be- 
comes flattened,  plexiform,  and  riband-shaped,  fur- 
nishes some  large  branches  to  the  psoas,  and  anas- 
tomoses with  the  third  nerve. 

The  anterior  branch  of  the  third  lumbar  nerve  is 
twice  as  large  as  the  preceding,  passes  obliquely 
downward  and  outward,  and  is  joined  by  the  branch 
from  the  second  nerve,  which  greatly  increases  its 
size.  The  large  trunk  thus  formed,  after  a  short  course  divides  into  two  unequal  branch- 
es, which  diverge  at  a  very  acute  angle,  and  anastomose  with  two  branches  derived 
from  the  fourth  nerve,  to  constitute  the  crural  (g)  and  the  obturator  (A)  nerves. 

The  anterior  branch  of  the  fourth  lumbar  nerve  is  a  little  larger  than  the  third ;  it  divides 
after  a  short  course  into  three  branches  :  an  external,  which  unites  with  the  external 
bifurcation  of  the  third  to  form  the  crural  nerve ;  a  middle,  which  unites  with  the  internal 
bifurcation  of  the  same  nerve  to  form  the  obturator  nerve ;  and  an  internal,  vertical,  an- 
astomotic branch,  which  joins  the  fifth  nerve. 

The  anterior  branch  of  the  fifth  lumbar  nerve  (5 1)  is  somewhat  larger  than  the  fourth  ;  it 
receives  the  internal  branch  of  that  nerve,  and  with  it  forms  a  large  trunk,  which  enters 
the  sacral  plexus,  and  was  named  by  Bichat  the  lumbosacral  nerve  (i). 

The  Lumbar  Plkxus. 

The  lumbar  plexus  (fig.  290)  (lumbo-abdominal,  Bichat)  is  a  rather  complicated  inter- 
lacement, formed  by  the  anastomoses  of  the  anterior  branches  of  the  lumbar  nerves.  It 
is  narrow  above,  where  it  consists  of  the  sometimes  slender  communicating  cord  be- 
tween the  first  and  second  lumbar  nerves,  and  it  becomes  wider  towards  its  lower  part, 
so  as  to  have  a  triangular  form ;  it  is  situated  upon  the  sides  of  the  lumbar  vertebrae,  be- 
tween the  transverse  processes  and  the  fasciculi  of  the  psoas  muscle. 

The  branches  which  emanate  from  the  lumbar  plexus  are  divided  into  terminal  branch- 
es, namely,  the  crural  (g),  obturator  (A),  and  lumbosacral  nerves  (i) ;  and  collateral  branches, 
improperly  named  musculo-cutaneous ;  these  are  four  in  number ;  they  run  between  the 
psoas  and  iliacus  and  the  peritoneum,  and  reach  the  femoral  arch.  I  shall  divide  these 
collateral  branches  into  two  sets :  an  abdominal  set,  subdivided  into  the  great  (a)  and 
small  (above  b) ;  and  an  inguinal  set,  subdivided  into  the  internal  (i)  and  external  (c).* 

Of  these  collateral  branches,  the  abdominal  only  run  in  the  sub-peritoneal  adipose  tis- 
sue, the  inguinal  branches  being  covered  by  a  layer  of  fascia,  which  keeps  them  in  con- 
tact with  the  psoas  iliac  muscle. 

Collateral  Branches  of  the  Lumbar  Plexus. 
Jlbdominal  Branches. 
The  abdominal  branches  of  the  lumbar  plexus  are  intended  for  the  parietes  of  the  abdo- 

*  A  change  in  the  nomenclature  of  the  collateral  branches  of  the  lumbar  plexus  appeared  to  me  to  be  ne- 
cessary. Bichat,  who  first  distinguished  them  by  special  names,  divides  them  into  external  or  musculo-cuta- 
neous branches,  and  an  internal  or  genito-crural  branch.  Of  the  three  external  branches,  Chaussier  named 
the  external  the  ilio-sr'o'al.  and  the  internal  the  inguino-culaneous  ;  the  intermediate  one,  to  which  he  gave 
no  particular  name,  -  ■  ~  its  old  appellation  of  the  midd/e  JrancA.  ■.-     • 


798  NEUROLOGY. 

men,  and  form  a  continuous  series  with  the  dorsal  nerves,  to  which  they  are  very  anal- 
ogous as  regards  their  distribution.* 

The  great  ahdominal  nerve  {a,  fig.  270)  is  the  most  external,  or,  rather,  the  highest  of 
the  branches  which  come  from  the  lumbar  plexus  (it  is  the  superior  musculo-cutaneous 
nerve  of  Bichat) ;  the  terms  ilio-inguinal  and  ilio-scrotal,  which  are  generally  applied  to 
it,  are  derived  from  the  fact  of  its  giving  a  small  cutaneous  branch  to  the  pubic  region.  + 

It  arises  from  the  first  lumbar  nerve,  of  which  it  may  be  regarded  as  a  continuation ; 
it  immediately  perforates  the  psoas,  becomes  sub-peritoneal,  runs  in  front  of  the  quad- 
r.itus  lumborum  obliquely  downward  and  outward,  through  the  sub-peritoneal  adipose 
tissue,  parallel  to  the  twelfth  dorsal  nerve,  and  thus  reaches  the  crest  of  the  ilium  to 
the  outer  side  of  the  quadratus  lumborum.  It  next  passes  obliquely  through  the  aponeu- 
rotic attachments  of  the  transversalis,  runs  along  the  crest  of  the  ilium  between  that 
muscle  and  the  obliquus  internus,  and  divides  into  two  branches,  the  abdominal  branch, 
properly  so  called,  and  the  pubic  branch. 

The  abdominal  branch,  properly  so  called,  runs  inward  between  the  transversalis  and 
the  internal  oblique,  parallel  to  the  abdominal  branch  of  the  twelfth  dorsal  nerve,  with 
which  it  almost  always  anastomoses,  and  soon  divides,  like  the  lower  intercostal  nerves, 
into  two  filaments,  one  of  which  perforates  the  rectus,  while  the  other,  after  having  en- 
tered the  sheath  of  that  muscle,  perforates  it  and  ramifies  upon  the  skin. 

The  pubic  branch  (a,  fig.  292)  continues  in  the  original  course  of  the  nerve  :  opposite 
the  anterior  superior  spinous  process  of  the  ilium,  and  often  much  beyond  that  point,  it 
receives  an  anastomotic  twig  from  the  small  abdominal  nerve  {¥),  and  sometimes  even 
the  whole  of  that  nerve,  runs  parallel  to  the  femoral  arch,  at  a  variable  distance  above 
it,  meets  with  the  spermatic  cord  in  the  male,  and  the  round  ligament  in  the  female, 
emerges  from  the  anterior  orifice  of  the  inguinal  canal  {a,  fig.  291),  is  reflected  outward 
upon  the  superior  angle  of  that  orifice,  and  then  expands  into  internal  or  pubic  filaments, 
which  are  distributed  to  the  skin  of  the  pubes,  and  external  filaments,  which  supply  the 
skin  of  the  fold  of  the  groin ;  this  pubic  branch  sometimes  divides  behind  the  femoral 
arch  into  two  filaments,  which  escape  separately  from  the  inguinal  ring. 

At  the  point  where  the  great  abdominal  nerve  reaches  the  crest  of  the  ilium,  it  very 
frequently  divides  into  two  branches,  a  gluteal  cutaneous,  which  crosses  obliquely  over 
the  crest  of  the  ilium,  and  an  abdominal,  properly  so  called,  which  is  distributed  in  the 
manner  just  described  ;  in  this  case,  the  great  abdominal  nerve  has  an  analogous  distri- 
bution to  that  of  the  dorsal  nerves. 

The  small  abdominal  or  small  musculo-cutaneous  nerve  (above  b.  Jig.  290),  the  second 
branch  derived  from  the  lumbar  plexus,  counting  from  without  inward  (the  middle  muscu- 
lo-cutaneous of  Bichat),  is  merely  an  accessory  of  the  great  abdominal  nerve,  sometimes 
arising  from  it,  often  applied  to  it,  and  always  anastomosing  with  it.  It  crosses  oblique- 
ly over  the  anterior  surface  of  the  quadratus  lumborum,  and  then  over  the  iliacus,  and  is 
sometimes  directed  obliquely  outward  towards  the  anterior  superior  spine  of  the  ilium, 
to  join  the  pubic  branch  of  the  great  abdominal  nerve,  with  which  it  is  blended  ;  it  some- 
times runs  alone  between  the  transversalis  and  internal  oblique :  having  reached  the 
middle  of  the  femoral  arch,  it  anastomoses  {b',fig.  291)  by  a  single  twig  with  the  pubic 
branch  of  the  great  abdominal  nerve,  runs  along  the  femoral  arch  below  and  parallel  to 
that  branch,  and  terminates  in  the  same  manner,  that  is  to  say,  in  the  skin  of  the  pubes 
and  groin.  I  have  seen  it  give  off  a  small  branch  to  the  lower  part  of  the  rectus  ab- 
dominis. The  small  abdominal  nerve  deserves  the  name  of  ilio-scrotal  as  much  as  the 
great  abdominal.  If  this  denomination  is  to  be  preserved,  it  might  be  called  the  small 
ilio-scrotal. 

The  Inguinal  Branches. 

The  external  inguinal,  or  external  cutaneous  nerve  (c,  fig.  290),  the  third  branch  of  the 
lumbar  plexus,  counting  from  without  inward  (inguino-cutaneoiis,  Chauss. ;  inferior  mus- 
culo-cutaneous, Bichat),  is  intended  exclusively  for  the  integuments  of  the  external  and 
posterior  regions  of  the  thigh.  It  generally  comes  off  from  the  second  lumbar  nerve  :  I 
have  seen  it  arise  by  a  common  trunk  from  the  second  and  third  lumbar  nerves,  and  I 
have  also  seen  it  come  off  from  the  outer  side  of  the  crural  nerve.  It  arises  by  one  and 
often  by  two  cords,  which  unite  as  they  emerge  from  the  psoas,  or  within  the  substance 
of  that  muscle.  In  either  case,  the  nerve  passes  obliquely  through  the  back  part  of  the 
psoas,  crosses  the  iliacus,  being  bound  down  by  a  layer  of  fascia,  and  then  gains  the  an- 
terior superior  spinous  process  of  the  ilium,  below  which  it  emerges  {cfig.  291)  from  the 
abdomen,  passing  behind  the  femoral  arch,  and  apparently  increasing  in  size  during  its 
passage. 

Below  the  femoral  arch  the  nerve  is  sub-aponeurotic,  or,  rather,  is  situated  in  a  sheath 

*  The  varieties  ^¥hich  they  prpsent  as  to  their  number,  origin,  and  divisions,  render  their  description  diffi- 
cult ;  I  shall  point  out  the  most  important  varieties  as  we  proceed. 

t  I  have  frequently  found  the  great  abdominal  branch  divided  into  two  distinct  branches,  which  anastomosed 
upon  the  crest  of  the  ilium,  and  then  had  a  common  distribution.  I  have  seen  the  uppermost  division  lying 
»o  close  to  the  twelfth  dorsal  nerve  that  it  might  have  been  taken  for  a  branch  of  that  nervo. 


THE    INGUINAL   BRANCHES,    ETC.  799 

formed  by  the  deepest  layers  of  the  fascia  lata,  and  divides  into  two  cutaneous  branches 
(c  c,fig.  292),  a  posterior  or  gluteal,*  and  an  anterior  or  femoral. 

The  posterior  or  gluteal  branch  turns  very  obliquely  outward,  downward,  and  backward, 
crosses  the  tensor  vaginae  femoris,  and  is  distributed  to  the  skin  of  the  posterior  region 
of  the  thigh.  It  is  sometimes  derived  from  the  internal  inguinal  nerve,  and  then  emerges 
from  the  abdomen  on  the  outer  side  of  the  external  inguinal  nerve,  crossing  obliquely  in 
front  of  it.  When  the  great  abdominal  nerve  (ilio-scrotal  of  authors)  gives  off  a  cuta- 
neous gluteal  branch,  there  is  only  a  trace  of  this  posterior  branch  of  the  external  ingui- 
nal nerve. 

The  anterior  or  cutaneous  branch  divides  into  two  others,  which  diverge  at  an  acute 
angle  :  one  is  external,  the  other  hiternal ;  the  external  branch  gives  off  a  series  of  fila- 
ments, which  pass  backward  and  downward,  forming  loops  with  their  concavities  turned 
upward,  and  is  then  lost  towards  the  lower  third  of  the  thigh ;  its  place  is  then  supplied 
by  the  internal  branch,  which  had  at  first  descended  vertically,  but  now  turns  outward 
and  backward,  and  is  distributed  over  the  outer  and  fore  part  of  the  knee. 

These  several  divisions  of  the  external  inguinal  nerve  lie  in  contact  with  the  femoral 
fascia,  and  their  ultimate  filaments  are  applied  to  the  skin. 

The  internal  inguinal  nerve  (branche  genito-crurale,  Bichat ;  rameau  sous-pubien, 
Chauss.,  b.  Jig.  290)  arises  from  the  second  lumbar  nerve,  passes  directly  forward 
through  the  psoas,  from  which  it  emerges  at  the  side  of  the  bodies  of  the  lumbar  verte- 
brae, runs  vertically  downward  upon  the  anterior  surface  of  the  muscle  covered  by  a  very 
thin  layer  of  fascia,  and  having  arrived  within  a  greater  or  less  distance  from  the  femo- 
ral arch,  divides  into  two  branches,  an  internal  or  scrotal,  and  an  external  ot  femoral  cuta- 
neous branch  (e).  Not  unfrequently  this  division  takes  place  as  the  nerve  emerges  from 
the  psoas.  Sometimes,  indeed,  the  genito-crural  nerve  is  double,  but  this  arises  merely 
from  its  early  subdivision.  During  its  course,  the  internal  inguinal  nerve  is  crossed  by 
the  ureter  and  covered  by  the  spermatic  vessels.  + 

The  internal  or  scrotal  branch  (e,  fig.  290)  crosses  over  the  front  of  the  femoral  artery, 
gains  the  internal  orifice  of  the  inguinal  canal,  crosses  the  epigastric  artery,  and,  before 
entering  the  inguinal  canal,  gives  off  several  filaments,  which  are  reflected  upward,  and 
dip  into  the  substance  of  the  internal  oblique  and  transversalis ;  the  scrotal  branch  is 
placed  below  the  spermatic  cord,  from  which  it  is  perfectly  distinct,  runs  with  it  through 
the  whole  length  of  the  inguinal  canal  {b,fig.  291),  rests  upon  the  reflected  portion  of  the 
femoral  arch  or  Gimbernat's  ligament,  and  emerges  from  the  external  orifice  of  the  in- 
guinal canal,  opposite  the  lower  end  of  the  external  pillar  :  at  this  point  it  is  reflected, 
passes  vertically  downward  behind  the  cord,  and  ramifies  in  the  skin  of  the  scrotum  of 
the  male,  and  of  the  labia  majora  in  the  female. 

The  femoral  cutaneous  branch  gains  the  crural  ring ;  but  before  entering  the  ring,  it 
gives  off  a  great  number  of  very  delicate  filaments,  which  are  reflected  upward  behind 
the  arch,  to  be  distributed  to  the  lower  part  of  the  psoas-iliac  and  transverse  muscles  : 
it  then  passes  through  the  crural  ring,  in  contact  with  its  outer  angle,  and  crosses  the 
circumflex  ilii  artery  at  its  origin,  just  as  we  have  shown  that  the  scrotal  nerve  crosses 
the  epigastric  artery ;  after  leaving  the  crural  ring  (e,  figs.  291,  292),  it  lies  beneath  the 
fascia,  but  soon  becomes  sub-cutaneous,  anastomoses  with  a  cutaneous  branch  of  the 
crural  nerve,  and  may  be  traced  beyond  the  middle  of  the  thigh,  t 

I  have  already  stated,  in  describing  the  external  inguinal  nerve,  that  the  posterior  or 
gluteal  cutaneous  branch  of  the  external  inguinal  nerve  is  often  given  off  by  the  internal 
inguinal  nerve.  In  that  case,  this  branch  runs  outward,  crosses  the  external  nerve  at  a 
very  acute  angle  under  the  femoral  arch,  and  escapes  from  below  the  arch  on  the  outer 
side  of  that  nerve  to  turn  round  the  tensor  vaginae  femoris.  Not  unfrequently  the  fila- 
ments for  the  lower  part  of  the  internal  oblique  and  transverse  muscles  arise  by  one  or 
more  distinct  branches. 

,  The  Terminal  Branches  of  the  Lumbar  Plexus. 

These  are  three  in  number,  viz.,  the  obturator  nerve,  the  crural  nerve,  and  the  great 
communicating  branch  between  the  lumbar  and  sacral  plexus,  called  the  lumbosacral 
trunk  or  nerve,  which  I  regard  as  a  dependance  of  the  sacral  plexus. 

The  Obturator  JVerve. 
The  obturator  nerve  (A,  fig.  290),  which  is  distributed  exclusively  to  the  external  obtu- 

*  Not  unfrequently  the  external  inguinal  nerve  gives  off  a  third  and  very  small  internal  branch,  which  lies 
immediately  in  contact  with  the  skin  of  the  anterior  region  of  the  thigh,  and  may  be  traced  as  far  as  the  lower 
third  of  that  region.     This  branch  always  anastomoses  with  a  cutaneous  branch  of  the  crural  nerve. 

t  Sometimes  a  small  filament  comes  off  from  the  genito-crural  nerve  while  it  is  still  within  the  substance 
of  the  psoas,  descends  vertically  on  the  inner  side  of  this  nerve,  gives  off  a  filament  which  is  lost  upon  the  ex- 
ternal iliac  artery,  and  then  again  becomes  united  with  the  nerve  from  which  it  had  been  given  off. 

t  In  order  to  assist  the  memory,  by  connecting  these  nerves  with  important  parts,  I  am  in  the  habit  of  call- 
ing the  femoral  cutaneous  branch  of  the  internal  inguinal  nerve  the  branch  of  the  crural  ring,  and  the  scrotal 
branch,  the  branch  of  the  inguinal  canal.  The  scrotal  branch  may  be  cut,  in  relieving  the  stricture  in  inguinal 
hernia,  by  the  division  of  Gimbernat's  ligament ;  and  the  femoral  cutaneous  branch  may  be  wounded  when  the 
external  angle  of  the  crural  ring  is  divided  for  the  relief  of  femoral  hernia. 


800 


NEUROLOGY. 


rator  muscle,  to  the  three  adductors  of  the  thigh,  and  to  the  gracihs,  is  the  smallest  of 


Fig.  291. 


I'^'N- 


\  m 


the  terminal  branches  of  the  lumbar  plexus ;  it  arises  from  the 
third  and  fourth  lumbar  nerves  by  two  equal  branches,  which 
unite  at  an  acute  angle  ;  it  perforates  the  psoas,  passes  under  the 
angle  of  bifurcation  of  the  common  iliac  artery  and  vein,  runs 
along  the  inner  surface  of  the  psoas,  crosses  very  obliquely  over 
the  sides  of  the  brim  of  the  pelvis,  and  is  then  placed  below 
the  external  iliac  vessels,  with  which  it  forms  an  acute  angle, 
and  above  the  obturator  artery :  throughout  the  whole  of  this 
course,  it  is  enveloped  in  the  sub-peritoneal  cellular  tissue  of  that 
region,  and,  thus  flattened  and  enlarged,  reaches  the  internal  ori- 
fice of  the  obturator  or  sub-pubic  canal,  on  emerging  from  which 
it  expands  into  diverging  branches  (A,  fig.  291)  for  the  adductors 
and  the  gracilis  muscle  of  the  thigh. 

Collateral  Branch. — The  obturator  nerve  gives  off  no  branch  in 
the  pelvis :  during  its  passage  through  the  obturator  or  sub-pubic 
canal,  it  gives  two  filaments  to  the  obturator  cxternus ;  one  of  these 
penetrates  the  upper  border  of  the  muscle,  and  the  other  enters 
at  its  anterior  surface.*  The  obturator  intemus  receives  no  fila- 
ment from  the  obturator  nerve. 

Terminal  Branches. — These  are  four  in  number  ;t  three  of  them, 
constituting  a  superficial  set,  pass  under  the  pectineus,  and  are  dis- 
tributed as  follows  :  the  internal  to  the  gracilis,  the  external  to  the 
adductor  longus,  and  the  middle  to  the  adductor  brevis  ;  the  fourth, 
which  is  more  deeply  seated,  belongs  to  the  adductor  magnus. 

The  branch  for  the  gracilis  expands,  as  it  enters  the  muscle,  into 
several  filaments,  the  largest  of  which  (r,fig.  291)  runs  for  some 
distance  upon  the  internal  surface  of  the  muscle  before  termi- 
nating in  it. 

The  branch  for  the  adductor  longus  enters  the  upper  border  and 
deep  surface  of  the  muscle :  a  rather  large  division  (q)  of  this 
branch,  taking  a  different  course,  passes  sometimes  in  front  of 
and  sometimes  behind  the  muscle,  which  is  crossed  by  the  nerve 
in  the  first  case,  and  perforated  by  it  in  the  second ;  the  nerve 
then  divides  into  several  filaments,  some  of  which  anastomose 
with  the  accessory  branch  (at  m)  of  the  internal  saphenous  nerve, 
while  another  anastomoses  with  the  saphenous  nerve  itself,  and 
a  third  terminates  in  the  synovial  membrane  of  the  knee-joint : 
this  is  an  articular  nerve  ;  it  may  unite  with  the  articular  branch 
of  the  nerve  for  the  vastus  internus.  The  anastomotic  division 
of  the  branch  for  the  adductor  longus  is  sometimes  as  large  as  the 
musculfu:  branch  itself  t 

The  branch  for  the  adductor  brevis  crosses  the  upper  border  of 
that  muscle,  expands  upon  it,  but  does  not  enter  it  until  it  reaches 
the  middle  ;  there  is  almost  always  an  anastomotic  twig,  which 
joins  the  internal  saphenous  branch  of  the  crural  nerve.<J 

The  fourth  branch,  or  branch  for  the  adductor  magnus,  is  the  deep' 
est ;  it  passes  between  the  adductor  brevis  and  magnus,  and  ram- 
ifies in  the  last-mentioned  muscle.  II 

*  [It  also  gives  off,  in  this  situation,  articular  filaments  to  the  hip-joint ;  these 
are  small  or  absent  when  the  articular  branches  of  the  accessory  to  the  obturator 
are  large.]  ...  . 

t  [Before  dividing  into  its  terminal  branches,  the  obturator  is  joined  by  its  ac- 
cessory nerve  (see  notes,  infra) ;  it  supplies  a  separate  branch  to  the  pectineus 
■when  that  from  the  accessory  nei-ve  is  wanting.] 

t  See  note,  tn/rd.  ,.     l_, 

^  In  a  great  number  of  subjects  I  have  found  a  small  nervous  cord,  which  sometimes  came  oit  from  the  third 
lumbar  nerve,  sometimes  from  the  obturator  itself,  and  which  may  be  called  the  accessory  of  the  obturator 
nerve,  or  the  nerve  of  the  coxo-femoral  articulation  ;  it  perforates  the  psoas  to  reach  its  inner  surface,  runs  par- 
allel to  and  above  the  obturator  nerve,  gains  the  pul)es,  which  it  crosses  on  the  inner  side  of  the  ilio-pectineal 
eminence,  with  which  it  is  in  contact,  dips  beneath  the  pectineus,  and  anastomoses  with  the  internal  saphenous 
nerve,  passing  into  the  angle  of  bifurcation  of  the  femoral  artery,  where  it  gives  off  the  profunda.  Opposite 
the  pubes  it  gives  off  several  branches,  which  perforate  the  fibrous  capsule  of  the  coxo-femoral  articulation, 
and  are  distributed  to  the  synovial  membranes.  [This  small  accessory  nerve  was  first  described  by  Schmidt. 
As  it  passes  under  the  pectineus  it  partially  supplies  that  muscle  ;  its  anastomotic  branch  is  described  as  uni- 
ting with  the  obturator  nerve  beneath  the  pectineus,  and  not  with  the  internal  saphenous  (see  also  notes  p. 
infra,  et  803).  The  articular  branch  was  believed  by  Schmidt  to  end  in  the  fat  near  the  acetabulum,  w  heii  tne 
accessory  nerve  is  small,  the  articular  filaments  and  the  branch  to  the  pectineus  are  replaced  by  others  from 
the  trunk  of  the  obturator  itself  In  the  pelvis  the  nerve  has  been  seen  to  give  filaments  to  the  levator  am.— 
(Schmidt.  I)e  Ncrvis  Lumbalibus  eorumque  Plexu,  1794  ;  Dr.  Alex.  Thomson,  Lond.  Med.  and  Surg.  Journal, 
tios.  95,  iXi :  'E]V\s,  Demonstrations  of  Anatomt/).'i 

II  [In  the  dissections  of  Schmidt,  Thomson,  and  Ellis,  the  branches  of  the  obturator  nerve  were  found  to 
have  a  much  more  extensive  distribution  than  that  described  in  the  text.  According  to  their  observations, 
»ne  of  the  superficial  branches,  which  is  named  the  long  cutaneous  nerve  (q,fig.  291),  and  which  corresponds 


THE    CRUKAL    NERVE.  8QJ 


^ 


^^;.     •  .  yv.i.  .„>r,i-  The  Crural  J^erve.  .     ^♦.rr**^;r:;. '  - 

The  crural  nerve  {g,]ig.  290)  is  the  external  terminal  hraiu^'.i  ol'  the  lumbar  plexus; 
the  third  and  fourth  lumbar  nerves  arc  almost  entirely  devoted  to  the  formation  of  thja 
large  branch,  which  supplies  all  the  muscles  of  the  anterior  region  of  the  thigh,  and  the 
integuments  of  the  anterior  regions  of  the  thigh,  leg,  and  foot. 

After  emerging  from  the  psoas,  the  crural  nerve  is  lodged  in  the  groove  betw^een  the 
psoas  and  iliacus  ;  it  escapes  from  the  pelvis  with  this  muscle,  in  the  sheath  of  which 
it  is  contained  :  having  arrived  below  the  femoral  arch  (^,  jig.  291),  it  turns  slightly  out- 
ward, becomes  flattened  and  widened,  and  immediately  divides  into  a  great  number  of 
diverging  branches.  The  nerve  sometimes  bifurcates,  and  then  gives  off  these  different 
branches. 

Relations. — In  the  iliac  fossa,  the  crural  nerve  is  covered  by  the  iliac  fascia,  and  is 
separated  by  the  psoas  from  the  external  iliac  artery  and  vein.  Opposite  the  femoral 
arch  it  always  occupies  the  groove  between  the  psoas  and  iliacus,  and  is  situated  on  the 
outer  side  of  the  femoral  artery,  being  separated  from  the  vessel  by  the  psoas,  which  is 
very  narrow  at  that  point.  It  is  of  importance  to  remark,  that  the  crural  nerve  is  not 
contained  in  the  sheath  of  the  femoral  vessels,  but  is  separated  from  them  by  the  iliac 
fascia  (see  ^^.  136). 

Collateral  Branches. — ^In  the  pelvis,  the  crural  nerve  gives  off  from  its  outer  side  a 
great  number  of  small  branches  {iliac  branches),  which  enter  separately  into  the  iliacus 
muscle,  after  having  run  for  some  distance  obliquely  downward  and  outward  upon  the 
surface  of  that  muscle.  Only  one  branch  enters  the  psoas.  One  of  the  branches  for  the 
iliacus  is  very  long,  and  descends  vertically  in  front  of  that  muscle,  into  which  it  enters, 
after  having  turned  round  its  outer  border.  I  have  already  said  that  the  external  ingui- 
nal nerve  {ingiiino-cutaneous  of  authors)  not  unfrequently  arises  from  the  crural  nerve. 

Of  the  terminal  branches  of  the  crural  nerve  there  are  two  which  arise  in  front  of  the 
others :  these  are,  the  musculo-cutaneous  nerve,  and  the  small  nerve  for  the  sheath  of  the 
femoral  vessels.*  The  Other  branches  are,  proceeding  from  without  inward,  the  branch 
for  the  rectus,  the  branches  for  the  vastus  externus,  the  branches  for  the  vastus  internus,  and 
the  cutaneous  branch,  called  the  internal  saphenous  nerve. 

The  Musculo-cutaneous  Crural  Nerve. 

This  nerve  passes  obliquely  downward  and  outward  between  the  sartorius  and  the 
psoas  and  iliacus,  and  immediately  expands  into  muscular  branches,  distributed  exclu- 
sively to  the  sartorius,  and  cutaneous  branches. 

The  muscular  branches  may  be  divided  into  the  short,  which  enter  the  upper  part  of  the 
sartorius,  and  the  long,  which  run  for  some  distance  upon  the  deep  surface  of  that  mus- 
cle, before  passing  into  it. 

The  cutaneous  branches  are  three  in  number  ;  two  of  them  perforate  the  sartorius  at 
different  points,  and  may  be  called  •perforating  branches.  I  shall  call  the  third  the  acces- 
sory branch  of  the  internal  saphenous  nerve. 

The  superior  perforating  cutaneous  or  middle  cutaneous  nerve  {f,fig.  291)  passes,  very 
obliquely,  through  the  upper  part  of  the  sartorius,  and  often,  as  it  emerges  from  that 
muscle,  anastomoses  with  a  branch  from  the  internal  inguinal  (genito-crural)  nerve  ;  it 
then  passes  vertically  downward,  parallel  to  and  on  the  inner  side  of  the  external  ingui- 
nal (external  cutaneous)  nerve ;  it  Hes  in  contact  with  the  femoral  fascia  (/,  Jig.  292), 
or,  rather,  is  contained  in  a  proper  fibrous  sheath.  During  its  course,  the  superior  per- 
forating cutaneous  nerve  gives  off  internal  and  external  cutaneous  filaments,  and  bifur- 
cates, opposite  the  middle  of  the  thigh,  into  two  branches  of  equal  size,  which  run  par- 
allel to  each  other,  gradually  diminishing  in  size,  and  may  be  traced  down  to  the  skin 
over  the  patella. 

io  the  anastomotic  division  of  the  branch  for  the  adductor  longus,  gives  off  cutaneous  branches  (q,fig.  292), 
which  perforate  the  fascia  to  the  inner  side  of  the  sartorius  muscle,  and  supply  the  skin  on  the  inner  part  of 
the  thigh  ;  it  also  gives  anastomotic  branches  to  the  plexus  (m,  Jig.  291 )  formed  in  the  middle  of  the  thigh,  and 
sometimes  an  articular  filament  to  the  knee  {these  anastomotic  and  articular  branches  are  described  in  the 
text,  p.  800)  ;  it  then  ends  in  a  descending  cutaneous  branch,  which  perforates  the  fascia  near  the  knee  (r,fig. 
292),  communicates  with  the  intern.al  cutaneous  and  internal  saphenous  nerves,  and  is  distributed  to  the  skin 
on  the  inner  and  back  part  of  the  two  upper  thirds  of  the  leg.  The  deep  branch  of  the  obturator  gives  off 
within  the  upper  part  of  the  adductor  magnus  an  articular  filament  destined  for  the  knee-joint ;  this  filament 
descends  in  the  substance  of  the  adductor  near  the  linea  aspera,  and  enters  the  popliteal  space,  either  by  per- 
forating the  tendinous  insertion  of  the  muscle  about  its  lower  third,  or  by  coming  forward  on  the  front  of  that 
insertion,  and  then  passing  backward  through  the  opening  for  the  femoral  artery  :  having  reached  the  popli 
teal  space,  it  surrounds  the  artery  with  small  filaments,  and  enters  the  back  part  of  the  knee-joint. 

The  cutaneous  branches  just  stated  to  be  given  off  by  the  superficial  part  of  the  obturator  to  the  thigh  and 
leg,  and  the  articular  filament  given  by  the  deep  branch  of  the  obturator  to  the  knee-joint,  correspond,  in  their 
dittnbulion,  with  the  three  collateral  branches  described  by  M.  Cruveilhier  {p.  803)  as  arising  from  the  in- 
ternal saphenous  nerve  after  it  has  received  a  remarkable  branch  of  origin  from  the  obturator  nerve,  opposite  to 
the  commencement  of  the  profunda  artery  :  these  collateral  branches  of  the  internal  saphenous  were  never 
met  with  in  Mr.  Ellis's  dissections.  In  some  cases,  then,  it  seems  that  part  of  the  obturator  joins  the  internal 
saphenous,  which  afterward  gives  off  cutaneous  branches  to  the  thigh  and  leg,  and  an  articular  filament  to  the 
knee  ;  in  other  c:»ses,  again,  the  obturator  does  not  join  the  internal  saphenous,  the  above-mentioned  branches 
arise  directly  from  the  obturator,  and  the  internal  saphenous  gives  no  collateral  branches.] 

'  LThe  crural  nerve  also  gives  some  small  branches  (s,_^^.  292),  which  pass  inward  behind  the  femoral 
vessels,  enter  the  pectineus  muscle,  and  sometimes  the  psoas  also.1 

51 


802  NEUROLOGY. 

Tlie  inferior  perforating  cutaneous  or  internal  cutaneous  nerve  {I,  fig.  291)  run  along 
the  inner  border  of  the  sartorius,  enclosed  in  its  sheath,  passes  obliquely  through  the 
muscle  at  the  middle  of  the  thigh,  but  perforates  the  femoral  fascia  much  lower  down  {I, 
Jig.  292) ;  it  descends  vertically,  in  contact  with  that  fiiscia,  and  having  arrived  opposite 
the  internal  condyle  of  the  femur,  is  reflected  forward  upon  itself,  describing  a  loop  with 
the  concavity  turned  upward  ;  it  thus  gains  the  patella,  runs  between  the  skin  and  the 
sub-cutaneous  bursa,  and  expands  into  a  number  of  diverging  filaments,  which  anasto- 
mose with  the  reflected  branch  (/ 1)  of  the  internal  saphenous  nerve  on  the  inner  side  of 
the  patella.  A  small  filament  often  remains  in  the  sheath  of  the  sartorius,  anastomoses 
upon  that  muscle  with  a  branch  from  the  accessory  of  the  internal  saphenous  nerve,  per- 
forates the  sheath  of  the  sartorius  opposite  the  knee,  and  anastomoses,  on  the  inner  side 
of  the  joint,  with  the  reflected  branch  of  the  internal  saphenous. 

The  accessory  cutaneous  branch  of  the  internal  saphenous  nerve  arises  from  the  mus:.  Ulo- 
cutaneous  nerve  on  the  inner  side  of  the  perforating  branches,  descends  vertically,  and 
divides  into  two  branches.  The  smaller  of  these  is  superficial  (n,  fig.  291) ;  it  enters  the 
sheath  of  the  sartorius,  runs  along  the  inner  border  of  the  muscle,  escapes  from  the 
sheath  below  the  middle  of  the  thigh,  crosses  the  adductor  and  the  gracilis,  and  is  in 
contact  with  the  internal  saphenous  vein  until  it  reaches  the  inner  side  of  the  knee, 
where  it  anastomoses  with  the  internal  saphenous  nerve.  The  other  branch,  the  satel- 
lite nerve  of  the  femoral  artery,  crosses  obliquely  over  the  nerve  for  the  vastus  internu* 
and  the  internal  saphenous  nerve,  and  is  situated  in  front  of  the  latter,  runs  along  the 
femoral  artery,  covering  the  lower  fourth  of  that  vessel,  and  crosses  very  obliquely  over 
it,  then  passes  over  the  tendon  of  the  adductor  magnus,  and,  having  reached  the  fibrous 
ring  through  which  the  femoral  artery  passes,  it  expands  into  a  great  number  of  fila- 
ments, of  which  one  anastomoses  with  the  preceding  branch  (w),  another  joins  the  obtu- 
rator nerve  (at  m),  and  a  third  unites  with  the  internal  saphenous  nerve  ;  a  sort  of  plex- 
us is  thus  formed  which  gives  origin  to  several  nerves  that  cross  obliquely  over  the  gra- 
cilis, to  be  distributed  to  the  skin  upon  the  posterior  region  of  the  leg. 

The  Small  Nerve  for  the  Sheath  of  the  Femoral  Vessels. 

This  branch,  which  often  comes  oflT  separately  from  the  lumbar  plexus,  is  situated, 
like  the  musculo-cutaneous,  in  front  of  the  other  branches  of  the  crural  nerve ;  it  then 
expands  into  a  great  number  of  very  slender  filaments,  which  surround  the  femoral  ar- 
tery and  vein.  Two  of  these  filaments,  of  which  one  passes  in  front  of  and  the  other 
behind  the  femoral  artery,  unite  to  form  a  small  nerve  {p,fig3.  291,  292),  that  escapes  by 
the  opening  (p)  for  the  internal  saphenous  vein,  and  accompanies  the  vein  for  a  great 
part  of  its  course.  Not  unfrequently,  the  filaments  which  have  passed  between  the  ar- 
tery and  vein  perforate  a  lymphatic  ganglion.  Two  other  filaments  are  distributed  to 
the  adductor  brevis  and  adductor  longus  ;  several  of  them  turn  round  the  deep  femoral 
artery  and  vein,  to  become  sub-cutaneous,  and  anastomose  with  other  accompanying 
branches  of  the  femoral  vessels,  and  more  particularly  with  the  internal  saphenous  nerve. 

This  small  branch  presents  many  varieties.  I  have  seen  it  arise  separately  from  the 
fourth  lumbar  nerve,  and  it  then  runs  along  the  anterior  surface  of  the  crural  nerve. 

The  Nerve  for  the  Rectus  Femoris. 
The  nerve  for  the  rectus  femoris  arises  on  the  inner  side  of  the  preceding,  enters  the 
upper  part  of  the  deep  surface  of  the  muscle,  and  divides  into  a  superior  or  short  branch, 
which  passes  horizontally  outward  in  the  substance  of  the  muscle,  and  an  inferior  or  long 
branch,  which  lies  in  contact  with  its  inner  border,  and  enters  the  muscle  at  the  middle 
of  the  thigh. 

The  Nerve  for  the  Vastus  Externus. 
The  nerve  for  the  vastus  externus  sometimes  arises  by  a  common  trunk  with  the  pre-' 
ceding,  passes  obliquely  downward  and  outward  beneath  the  rectus,  to  which  it  gives  &., 
filament,  and  then  divides  into  two  branches :  one  of  these  immediately  enters  the  upper 
part  of  the  vastus  externus,  and  gives  off,  before  penetrating  it,  a  cutaneous  branch, 
which  perforates  the  fascia  lata  and  lies  in  contact  with  the  skin  of  the  external  region 
of  the  thigh :  the  other  is  longer,  dips  between  the  vastus  externus  and  internus,  and 
enters  the  middle  of  the  former  muscle.  This  last  branch  almost  always  gives  off  a 
sm8dl  twig  to  the  vastus  internus. 

The  Nerves  for  the  Vastus  Internus.* 
These  are  two  in  number  ;  the  one  is  external,  and  descending  vertically,  enters  that 
portion  of  the  vastus  internus  which  corresponds  to  the  anterior  surface  of  the  femur 
(the  crureus  of  authors),  and  may  be  traced  as  far  as  the  lower  part  of  the  muscle :  this 
nerve  furnishes  several  periosteal  and  articular  filaments ;  the  other  is  internal,  and  much 
larger ;  it  often  arises  by  a  common  trunk  with  the  internal  saphenous  nerve,  runs  ver- 
tically downward  in  front  of  the  vastus  internus,  parallel  to  and  on  the  outer  side  of  the 

*  It  will  be  remembered  that,  according  to  my  views,  the  portion  of  the  triceps  which  is  called  the  crurau 
is  not  distinct  from  the  vastus  internus  (see  Mvojlooy). 


THE  INTERNAL  SAPHENOUS  NERVE. 


m 


femoral  artery,  being  in  contact  with  that  vessel  above,  but  separated  from  it  below, 
where  it  enters  the  vastus  intemus.  Before  penetrating  it,  it  gives  off  a  very  remark- 
able articular  and  periosteal  branch,  which  runs  along  the  surface  of  the  muscle,  to  the 
aponeurosis  of  which  it  is  applied  :*  opposite  to  the  knee-joint  it  is  reflected  forward, 
perforates  the  thick  fibrous  layer  which  invests  the  inner  side  of  the  joint,  and  divides 
into  two  filaments,  of  which  one,  the  articular,  is  lost  behind  the  ligamentum  patellae  in 
the  quantity  of  adipose  tissue  which  is  found  there  ;  while  the  other,  or  the  periosteal, 
gains  the  anterior  surface  of  the  patella,  and  is  lost  in  the  periosteum.  This  last  filament 
is  re-enforced  upon  the  inner  border  of  the  patella  by  another  which  passes  out  from  the 
substance  of  the  vastus  intemus. 

The  Internal  Saphenous  Nerve.  ^-  292. 

The  internal  saptienous  nerve  {t  t',fig.  291),  the  satellite  nerve  .; 

of  the  femoral  artery  in  the  thigh,  and  of  the  internal  saphenous 
vein  in  the  leg,  is  at  first  situated  on  the  outer  side  of  the  ar- 
tery, but  soon  passes  in  front  of  that  vessel,  and  is  contained  in 
the  same  fibrous  sheath ;  when  the  artery  passes  through  the 
tendon  of  the  adductor  magnus  to  enter  the  popliteal  space,  the 
nerve  continues  its  vertical  course  in  front  of  that  tendon,  and 
crossing  it  very  obliquely  from  before  backward,  gains  the  back 
of  the  internal  condyle  of  the  femur,  situated  in  front  of  the  ten- 
don of  the  gracilis,  and  separated  from  the  skin  by  the  sartorius ; 
it  then  divides  into  two  terminal  branches  (m,  t',figs.  291,  292). 
This  division  often  takes  place  £is  the  nerve  is  crossing  the  ten- 
don of  the  adductor  magnus. 

Collateral  Branches. — At  its  upper  part,  the  internal  saphenous 
nerve  receives  from  the  obturator  nerve  a  remarkable  branch  of 
origin,  which  passes  from  behind  forward  in  the  angle  formed  by 
the  femoral  artery  and  the  profunda.!  It  then  gives  off  from  its 
inner  side,  at  the  middle  of  the  thigh,  a  cutaneous  femoral  branch, 
which  passes  between  the  sartorius  and  the  gracilis,  runs  back- 
ward and  downward,  and  is  distributed  to  the  skin  of  the  poste- 
rior and  internal  region  of  the  thigh.  Several  filaments  continue 
their  course  to  the  inner  and  back  part  of  the  knee,  anastomose 
with  some  branches  given  off  from  the  saphenous  nerve  in  the 
leg,  and  are  distributed  to  the  skin  of  the  internal  and  posterior 
region  of  the  leg. 

At  the  point  where  the  femoral  artery  perforates  the  adduc- 
tor magnus,  the  internal  saphenous  nerve  gives  off  a  second  or 
tibial  cutaneous  branch,  which  passes  between  the  sartorius  and 
gracilis,  turns  round  the  inner  border  of  the  latter  muscle,  pass- 
es vertically  downward  parallel  to  the  saphenous  nerve,  and  di- 
vides into  several  filaments,  some  of  which  anastomose  with 
that  nerve,  while  the  others  are  distributed  to  the  skin  upon  the 
internal  and  posterior  region  of  the  leg. 

In  the  sheath  of  the  adductor  magnus  the  saphenous  nerve 
gives  off  an  articular  filament,  which  passes  vertically  downward 
in  the  substance  of  the  internal  inter-muscular  septum,  gains  the 
knee-joint,  perforates  the  fibrous  layer,  and  may  be  traced  into 
the  synovial  adipose  tissue. t 

Terminal  Branches. — The  anterior,  reflected,  or  patellar  branch 
(u,  figs.  291,  292)  perforates  the  sartorius^  opposite  to  the  back 
of  the  internal  condyle,  is  reflected  forward  and  downward  in 
a  flattened  form  upon  the  inner  side  of  the  knee-joint,  parallel 
to  and  above  the  tendon  of  the  sartorius,  and  expands  widely 
into  ascending  filaments,  which  pass  in  front  of  the  ligamentum 
patellae,  and  turn  round  the  lower  and  then  the  outer  borders  of 
the  patella ;  into  descending  filaments,  which  cross  obliquely  over 
the  crest  of  the  tibia,  and  ramify  in  the  skin  which  covers  the 
external  region  of  the  leg  ;  and  into  middle  filaments,  which  oc- 
cupy the  space  between  the  two  preceding  sets  ;  they  are  all  dis- 
tributed to  the  skin,  and  several  of  them  anastomose  with  the  cu- 
taneous filaments  upon  the  external  region  of  the  patella. 

*  [In  this  situation  it  sometimes  receives  the  articular  filament  of  the  anasto- 
motic or  long  cutaneous  branch  of  the  obturator  nerve.] 

t  [This  junction  of  part  of  the  obturator  with  the  internal  saphenous  nerve  was  never  seen  in  the  dissec- 
tions of  Mr.  Ellis,  nor  did  the  saphenous  give  any  collateral  branch  in  the  thigh  ;  but  branches  correspond- 
ing in  their  distriliution  to  the  three  collateral  branches  described  in  the  text  arose  from  the  obturator  itself 
(see  also  note,  p.  800.)]  %  See  note,  p.  800. 

^  The  sartorius  is,  therefore,  perforated  in  succession  by  three  cutaneous  branches,  namely,  two  pprf.ii.i- 
ting  branches  from  the  musculo-cutaneous  nerve,  and  one  from  the  internal  st'  •nous. 


804  NEUROLOGY. 

The  posterior  or  straight  branch  {t')  is  larger  than  the  preceding,  and  continues  in  the 
original  course  of  the  nerve  ;  it  almost  always  receives  an  anastomotic  branch  from  the 
obturator  nerve,  passes  in  front  of  the  tendon  of  the  gracilis,  then  between  the  sartorius 
and  that  tendon,  which  it  crosses  very  obliquely,  to  meet  the  internal  saphenous  vein  («), 
whose  direction  it  then  follows  :  having  arrived  opposite  the  junction  of  the  three  upper 
fourths  with  the  lower  fourth  of  the  leg,  it  divides  into  two  branches ;  the  one,  posterior 
and  smaller,  passes  vertically  downward  in  front  of  the  internal  malleolus,  upon  which 
it  ramifies,  some  of  the  filaments  reaching  as  far  as  the  skin  upon  the  inner  side  of  the 
sole  of  the  foot ;  the  other  branch,  which  is  anterior  and  larger,  runs  along  the  internal 
saphenous  vein,  like  it,  is  situated  in  front  of  the  internal  surface  of  the  tibia,  then  in 
front  of  the  internal  malleolus,  and  expands  into  articular  branches,  which  enter  the  tib- 
io-tarsal  articulation,  and  into  cutaneous  filaments,  which  ramify  in  the  skin  upon  the 
inner  side  of  the  tarsus. 

The  following  are  the  relations  of  the  saphenous  nerve  with  the  internal  saphenous 
vein  :  the  nerve  is  at  first  placed  in  front  of  the  vein,  then  crosses  obliquely  under  it  to 
get  behind  it,  and,  lastly,  it  again  returns  to  its  position  in  front  of  the  vessel. 

During  its  course  along  the  leg,  the  posterior  branch  of  the  saphenous  nerve  gives  off 
some  internal  and  some  external  branches  :  the  internal  branches  are  very  small ;  the  up- 
per ones  anastomose  with  the  tibial  cutaneous  branch  of  the  trunk  of  the  internal  saphenous 
nerve,  and  concur  with  it  in  supplying  filaments  to  the  skin  of  the  back  of  the  leg.  The 
external  branches,  three  or  four  in  number,  are  large,  and,  in  this  respect,  diminish  from 
above  downward  ;  their  direction  is  obliquely  downward  and  outward,  in  front  of  the  tibia, 
which  they  cross  ;  their  course  is  a  long  one,  and  they  are  distributed  extensively  to  dif- 
ferent portions  of  the  skin  of  the  leg.  All  these  divisions  are  parallel  to  each  other,  and 
to  the  anterior  reflected  or  patellar  branch  of  the  saphenous  nerve. 


THE  ANTERIOR  BRANCHES  OF  THE  SACRAL  NERVE. 

Dissection. — Enumeration. — The  Sacral  Plexus. —  Collateral  Branches,  viz.,  the  Visceral 
Nerves — the  Muscular  Nerves  —  the  Inferior  Hemorrhoidal — the  Internal  Pudic  and  its 
Branches — the  Superior  Gluteal  Nerve — the  Inferior  Gluteal,  or  Lesser  Sciatic  Nerve — 
the  Nerves  for  the  Pyramidalis,  Quadratus  Femoris,  and  Gemelli. — Terminal  Branch  of 
the  Sacral  Plexus,  or  the  Great  Sciatic  Nerve. — The  External  Popliteal  and  its  Branches 
— the  Peroneal  Saphenous,  Cutaneous,  and  Muscular  Branches — the  Musculo-cutaneous — 
the  Anterior  Tibial. — The  Internal  Popliteal  and  its  Branches — the  Tibial  or  External 
Saphenous — Muscular  and  Articular  Branches — the  Internal  Plantar — the  External  Plan- 
tar.— Summary  of  the  Nerves  of  the  Lower  Extremity. — Comparison  of  the  Nerves  of  the. 
Upper  with  those  of  the  Lower  Extremity. 

Dissection. — Make  an  antero-posterior  section  of  the  pelvis,  as  in  dissecting  the  inter- 
nal iliac  artery. 

The  anterior  branches  of  the  sacral  nerves  (26  to  3\,fig.  268),  which  are  six  in  number, 
communicate  with  the  sacral  ganglia  of  the  sympathetic,  after  they  have  emerged  from 
the  sacral  foramina,  and  present  the  following  arrangement : 

The  first  nerve  (I,  fig-  290),  which  is  very  large,  passes  obliquely  downward  and  out- 
ward, in  front  of  the  pyriformis,  and  is  joined  at  a  very  acute  angle  by  the  lumbo-sacral 
nerve  (i),  to  assist  in  the  formation  of  the  sacral  plexus. 

The  second  nerve,  which  is  as  large  as  the  preceding,  passes  much  more  obliquely 
downward  and  outward,  and  immediately  enters  the  sacral  plexus. 

The  third  nerve  (3),  which  is  scarcely  one  fourth  as  large  as  the  second,  passes  more 
horizontally  outward  to  enter  the  sacral  plexus.  A  considerable  interval,  in  which  is  a 
large  part  of  the  pyriformis,  separates  it  from  the  second  nerve.  A  filament  stretched 
in  front  of  this  muscle  passes  from  the  second  to  the  third  sacral  nerve. 

The  fourth  nerve  (4),  which  is  only  one  third  the  size  of  the  third,  is  divided  and  dis- 
tributed in  the  following  manner :  One  of  its  divisions  assists  in  forming  the  sacral 
plexus  ;  it  gives  off  several  viscer^d  branches,  which  enter  the  hypogastric  plexus  ;  it 
communicates  with  the  fifth  sacral  nerve  by  another  division ;  it  gives  off  one  or  two 
branches  to  the  coccygeus  muscle  ;  and,  lastly,  it  gives  a  cutaneous  coccygeal  branch, 
which  runs  along  the  border  of  the  sacrum,  penetrates  the  great  sacro-sciatic  ligament, 
crosses  that  ligament  very  obliquely,  and  turns  round  its  lower  edge,  perforates  the  coc- 
cygeal attachments  of  the  glutseus  maximus,  passes  very  obliquely  through  the  muscle, 
gives  branches  to  it,  and  then  ends  in  the  integuments. 

The  fifth  and  sixth  nerves,  which  have  no  connexion  with  the  sacral  plexus,  are  ex- 
tremely small ;  the  fifth  is  not  more  than  half  the  size  of  the  fourth  ;  the  sixth  is  so  very 
slender  a  filament,  that  it  has  often  escaped  the  notice  of  anatomists,  and  hence  the  in- 
correct but  prevalent  opinion  that  there  frequently  exist  only  five  sacral  nerves. 

The  fifth  nerve,  at  its  exit  from  the  anterior  sacral  foramen,  divides  into  an  ascending 
branch,  which  comnaunicates  with  the  fourth,  and  a  descending  branch,  which  passes  di- 


COLLATERAL  BRANCHES  OF  THE  SACRAL  PLEXUS.        805 

recfty  downward  to  anastomose  with  the  sixth,  of  which  it  appears  to  form  the  ascend- 
ing branch. 

The  sixlh  nerve  consists  of  a  mere  filament,  which  divides,  while  still  contained  within 
the  sacral  foramen,  into  an  ascending  or  anastomotic  branch,  which  is  merely  the  de- 
scending branch  of  the  fifth  ;  a  descending  or  inferior  coccygeal  branch,  which  passes  ver- 
tically downward  along  the  coccyx  in  the  substance  of  the  sacro-sciatic  ligament,  and  is 
distributed  to  the  skin ;  and  certain  external  branches,  which  perforate  the  sacro-sciatic 
ligament,  and  terminate  in  the  glutaeus  maximus. 

The  Sacral  Plexus. 

The  sacral  plexus  {Jig.  290)  is  formed  by  the  four  upper  sacral  nerves  (1  to  4)  and  the 
lumbo-sacral  nerve  (i)  from  the  lumbar  plexus  ;  the  three  superior  sacred  nerves  pass 
entirely  into  this  plexus  ;  the  fourth  nerve  only  sends  one  of  its  divisions  to  it.  The 
lumbo-sacral  trunk  or  nerve,  which  emanates  from  the  lumbar  plexus,  is  formed  by  the 
whole  of  the  fifth  lumbar  nerve  add0  to  a  branch  from  the  fourth.  This  great  nervous 
trunk  establishes  a  free  connexion  between  the  lumbar  and  sacral  plexuses,  which,  in 
fact,  constitute  only  one  plexus,  which  may  be  called  the  lumbo-sacral.  I  would  here 
recall  to  mind  that  there  is  a  precisely  similar  arrangement  with  regard  to  the  cervical 
and  brachial  plexuses,  to  which  the  lumbar  and  sacral  plexuses  have  an  undoubted  an- 
alogy. 

The  sacral  plexus  is  distinguished  by  its  simplicity  from  most  other  plexuses,  which 
are  always  more  or  less  complicated.  It  is  formed  by  the  convergence  of  five  cords  to- 
wards the  sciatic  notch.  As  the  lumbo-sacral  cord  is  vertical,  and  the  third  and  fourth 
sacral  nerves  are  horizontal,  it  follows  that  the  form  of  the  sacral  plexus  resembles  a 
triangle,  the  base  of  which  measures  the  entire  length  of  the  sacrum,  while  its  apex 
corresponds  to  that  portion  of  the  sciatic  notch  which  is  situated  above  the  spine  of  the 
ischium.  The  great  sciatic  nerve  («)  is  the  continuation  of  this  plexus,  which,  as  Bichat 
judiciously  remarked,  is  merely  the  sciatic  nerve  itself  flattened  from  before  backward, 
the  intricacy  of  arrangement  so  evident  in  the  plexus  representing  that  which  exists  in 
all  nervous  cords. 

The  following  are  the  relations  of  the  sacral  plexus :  It  rests  behind  upon  the  pyri- 
formis,  and  it  corresponds  in  front  to  the  internal  iliac  vessels,  from  which  it  is  separa- 
ted by  a  layer  of  fascia :  these  vessels  also  separate  the  plexus  from  the  rectum  and 
peritoneum. 

Of  the  collateral  branches,  some  are  anterior,  namely,  the  visceral  nerves,  which  enter 
the  hypogastric  plexus ;  the  nerve  for  the  levator  ani ;  the  nerve  for  the  obturator  inter- 
nus ;  the  internal  pudic  nerve  :  the  other  collateral  branches  are  posterior,  namely,  the 
superior  gluteal  nerve ;  the  inferior  gluteal  or  lesser  sciatic  nerve ;  the  nerve  for  the 
pyriformis ;  the  nerve  for  the  geraelli ;  and  the  nerve  for  the  quadratus  femoris.  The 
great  sciatic  nerve  is  the  only  terminal  branch  of  the  sacral  plexus. 

The  Collateral  Branches  of  the  Sacral  Plexus. 

The  Visceral  Jferves. 

Dissection. — After  having  made  a  section  of  the  pelvis  at  one  side  of  the  symphysis, 
turn  the  bladder  and  the  rectum  over  to  the  same  side ;  carefully  detach  the  peritoneum, 
which  is  reflected  from  the  pelvis  upon  these  viscera ;  lacerate  the  cellular  tissue  to 
reach  the  branches  given  off"  from  the  fourth  nerve  ;  and  then  trace  the  rectal  and  vis- 
ceral nerves,  following  the  annexed  description.  It  is  advantageous  to  empty  the  large 
veins  of  the  pelvis,  and  to  soak  it  in  water  for  some  time  previously  to  dissecting  these 
nerves. 

The  visceral  nerves  do  not,  properly  speaking,  come  from  the  sacral  plexus,  but  rather 
directly  from  the  fourth  and  fifth  sacral  nerves ;  they  are  three  or  four  in  number,  and 
pass  upward  upon  the  sides  of  the  rectum  and  bladder  in  the  male,  and  of  the  rectum, 
vagina,  and  bladder  in  the  female  ;  some  of  them  are  distributed  directly  to  those  organs, 
but  the  greater  number  (y,  fig.  302)  enter  the  hypogastric  plexus  (m),  which  will  be  de- 
scribed with  the  sympathetic  system. 

The  JSTervesfor  the  Levator  Ani. 

Besides  several  rectal  and  vesical  filaments  which  go  to  the  levator  ani,  this  muscle 
receives  two  filaments  directly  from  the  fourth  sacral  nerve  (4,  fig.  290) :  the  larger  of 
these  filaments  enters  the  middle  of  the  muscle  ;  the  other,  which  is  smaller,  passes 
upon  the  sides  of  the  prostate  in  the  male,  and  of  the  vagina  in  the  female,  and  termi- 
nates in  the  anterior  portion  of  the  muscle. 

The  Nerve  for  the  Obturator  Internus. 

It  arises  from  the  anterior  part  of  the  sacral  plexus,  and  more  particularly  from  that 
portion  which  belongs  to  the  lumbo-sacral  cord  and  the  first  sacral  nerve ;  it  passes  im- 
mediately behind  the  spine  of  the  ischium,  is  reflected  forward  through  the  small  sciatic 


806  NEUROLOGY. 

notch,  and  expands  into  three  diverging  branches,  which  are  distributed  within  the  mus- 
cle.    In  order  to  expose  this  nerve,  the  lesser  sacro-sciatic  ligament  may  be  divided. 

The  Inferior  Hemorrhoidal  J^erve. 

This  nerve,  which  is  intended  for  the  sphincter  ani  and  the  adjacent  skin,  arises  (from 
4,  Jig.  290)  on  the  inner  side  of  the  internal  pudic  nerve,  of  which  it  is  sometimes  a 
branch,  passes,  like  that  nerve,  behind  the  spine  of  the  ischium,  and  then  between  the 
two  sacro-sciatic  ligaments,  reaches  the  front  of  that  portion  of  the  glutaeus  maxiraus 
which  projects  below  the  great  sacro-sciatic  ligament,  communicates  with  the  superfi- 
cial nerve  of  the  perineum,  gains  the  side  of  the  rectum,  and  opposite  the  upper  border 
of  the  sphincter  expands  into  a  great  number  of  branches  ;  of  these,  some  are  anterior, 
and  often  anastomose  with  one  of  the  divisions  of  the  superficial  perineal  nerve  ;  others 
are  median,  and  pass  upon  the  sides  of  the  sphincter  ani  as  far  as  the  skin,  in  which  they 
terminate ;  lastly,  others  are  posterior,  and  proceed  to  the  back  part  of  the  sphincter. 
The  hemorrhoidal  or  anal  nerve  is  sometimes  di^pbuted  exclusively  to  the  skin  round 
the  anus  ;  it  may  then  be  named  the  anal  cutaneoits  nerve. 

The  Internal  Pudic  JVerve. 

Dissection. — It  is  convenient  to  commence  the  dissection  of  this  nerve  from  within 
outward,  by  dividing  the  lesser  sacro-sciatic  ligament,  and  separating  the  obturator  fas- 
cia from  the  obturator  internus  muscle.  The  superior  branch  of  the  nerve  upon  the  dor- 
siun  of  the  penis  may  then  be  traced  without  taking  it  away.  The  perineal  branches 
must  then  be  very  carefully  dissected,  and  the  continuity  of  these  branches  with  those 
already  dissected  within  the  pelvis  should  be  made  out. 

The  internal  pudic  nerve  (d.  Jig:  293)  arises  from  the  lower  border  of  the  flattened 
band  formed  by  the  nerves  of  the  sacral  plexus  opposite  to  their  junction  ;  it  passes  be- 
hind the  spine  of  the  ischium,  and  then  enters  the  ischio-rectal  fossa  through  the  lesser 
sciatic  notch,  that  is,  between  the  two  sacro  sciatic  ligaments,  on  the  inner  side  of  the 
internal  pudic  artery,  and  divides  into  two  branches  (/,  Jig.  290),  the  injcrior  branch,  or 
'perineal  nerve,  and  the  superior  or  deep  branch,  or  the  dorsal  nerve  oj  the  penis. 

The  Perineal  Nerve. 

The  inferior  branch  or  perineal  nerve  corresponds  to  the  trunk  of  the  internal  pudic  ar- 
tery, and  to  all  its  divisions,  excepting  the  dorsal  artery  of  the  penis.  It  is  the  true  con- 
tinuation of  the  nerve,  and  accompanies  the  trunk  of  the  internal  pudic  arterj",  being  sit- 
uated below  that  vessel ;  it  runs  forward  and  then  upward  between  the  obturator  inter- 
nus and  the  obturator  fascia,  describes  a  curve  having  its  concavity  directed  upward,  and 
placed  on  the  inner  side  of  the  tuberosity  of  the  ischium,  perforates  the  obturator  fascia, 
opposite  to  the  junction  of  the  tuberosity  with  the  ascending  ramus  of  the  ischium,  and 
immediately  divides  into  two  branches  :  an  inferior  or  anterior  superficial  perineal,  which 
corresponds  to  the  superficial  artery  of  the  perineum  ;  and  a  superior,  which  corresponds 
to  the  artery  of  the  bulb,  but  which  has  a  much  more  extensive  distribution ;  I  shaU 
call  it  the  bulbo-urethral  nerve. 

The  Collateral  Branches  of  the  Perineal  Nerve. — During  its  course,  the  perineal  nerve 
gives  off  a  branch  which  might  l>e  called  the  external  perineal  ( posterior  superficial  perin 
eal) ;  this  branch  perforates  the  great  sacro-sciatic  ligament,  passes  by  the  internal  sur 
face  of  the  tuberosity  of  the  ischium,  turns  inward  and  downward,  and  then  beneath 
the  tuberosity,  runs  along  the  crus  of  the  corpus  cavernosum,  and  is  lost  in  the  dartos 
and  scrotum  in  the  male,  and  in  the  substance  of  the  labia  majora  in  the  female.  I  have 
seen  this  nerve  give  a  branch  to  the  coccygeus,  and  two  branches  to  the  sphincter. 

This  external  perineal  branch,  moreover,  presents  many  varieties.  In  some  cases  it 
terminates  by  anastomosing  with  the  superficial  branch  of  the  perineum.  In  one  case, 
in  which  the  external  perineal  branch  was  very  small,  it  was  re-enforced  by  a  branch  from 
the  inferior  gluteal  or  lesser  sciatic  nerve,  which  crossed  the  outer  side  of  the  tuberosity 
of  the  ischium,  and  united,  in  front  of  that  tuberosity,  with  the  external  perineal  branch. 

The  Terminal  Branches  of  the  Perineal  Nerve. — The  superjicial  {anterior  superjicial)  pe- 
rineal nerve  follows  the  superficial  artery  of  the  perineum,  passes,  like  it,  obUquely  in- 
ward and  forward,  through  the  cellular  interval  between  the  ischio-cavernosus,  and 
bulbo-cavernosus,  receives  a  rather  large  filament  from  the  external  perineal  branch,  and 
almost  always  divides  into  several  remarkably  long  filaments,  which  pass  through  the 
dartos,  some  reaching  the  bottom  of  the  scrotum,  while  others,  running  along  the  lower 
surface  of  Uie  penis,  are  distributed  to  the  skin  of  that  organ,  and  may  be  traced  as  far 
as  the  prepuce. 

The  bulbo-urethral  nerve,  the  second  terminal  branch  of  the  perineal  nerve,  passes 
above  and  sometimes  through  the  fibres  of  the  transversus  perinei  muscle,  supplies  some 
small  branches  to  the  anterior  part  of  the  compressor  urethrae  and  the  posterior  part  of 
the  bulbo-cavernosus,  furnishes  a  bulbar  branch  which  dips  into  the  substance  of  the 
bulb,  and  then  expands  into  very  delicate  filaments  on  the  corpus  spongiosum. 


DEEP  BRANCH  OF  THE  INTERNAL  PUDIC,  ETC.  "gOV 

The  Deep  Branch  of  the  Internal  Pudic,  or  the  Dorsal  Nerve  of  the  Perns. 

This  is  the  highest  of  the  terminal  divisions  of  the  internal  pudic  nerve,  and  corre- 
sponds to  the  deep  branch  of  the  internal  pudic  artery.  It  is  at  first  applied,  together 
with  that  vessel,  against  the  internal  surface  of  the  tuberosity  of  the  ischium,  and  pass- 
ing upward  between  the  levator  ani  and  obturator  internus,  gains  the  arch  of  the  pubes  ; 
it  then  runs  forward  among  the  sub-pubic  veins  through  the  several  ligamentous  struc- 
tures below  the  arch,  and  reaches  the  dorsum  of  the  penis,  where  it  is  situated  at  the 
side  of  the  suspensory  ligament.  Having  now  become  the  dorsal  nerve  of  the  penis,  it 
runs  along  that  organ  in  the  median  line,  like  the  dorsal  artery,  but  superficially  to  that 
vessel,  and  divides  into  an  internal  and  an  external  branch. 

The  internal  branch,  or  branch  for  the  glans  penis,  continues  in  the  original  course  of 
the  nerve  upon  one  side  of  the  median  line,  becomes  more  deeply  seated  as  it  runs  for- 
ward, but  without  entering  the  corpus  cavernosum,  and  thus  arrives  at  the  corona  glan- 
dis  ;  at  this  point  it  expands  and  passes  deeply  between  the  base  of  the  glans  and  the 
corpus  cavernosum,  gives  no  filament  to  the  latter,  but  is  entirely  distributed  to  the  glans, 
penetrating  that  part  by  extremely  delicate  filaments,  which  traverse  the  spongy  tissue, 
and  may  be  traced,  at  least  in  a  great  measure,  to  the  papillae  on  the  surface  of  the  glans. 

The  external  or  cutaneous  branch,  which  is  more  superficial,  comes  off  from  the  prece- 
ding at  a  very  acute  angle,  passes  obliquely  upon  the  sides  of  the  penis,  and  expands 
into  a  number  of  very  long  and  slender  filaments,  some  of  which  lie  in  contact  with  the 
corpus  cavernosum,  and  supply  it  with  very  slender  filaments,  "while  others  run  into  the 
sub-cutaneous  cellular  tissue,  and  are  distributed  to  the  skin  of  the  penis ;  a  considera- 
ble number  terminate  in  the  prepuce.  The  external  branch  of  the  dorsal  nerve  of  the 
penis  supplies  the  skin  upon  the  three  upper  fourths  of  the  circumference  of  the  penis. 
The  perineal  branches  supply  that  of  the  lower  fourth.  I  have  not  found  any  branch  of 
the  internal  pudic  nerve  corresponding  to  the  artery  of  the  corpus  cavernosum. 

In  the  female,  when  this  nerve  reaches  the  clitoris,  it  becomes  very  small ;  it  passes 
under  the  arch  of  the  pubes,  between  it  and  the  cms  of  the  clitoris  ;  it  runs  along  that 
crus,  becomes  curved  like  the  clitoris  itself,  upon  the  side  of  which  it  expands  into  fila- 
ments, and  then  ramifies  in  the  substance  of  that  organ  ;  several  of  the  filaments  run 
forward  to  the  skin  of  the  anterior  part  of  the  labia  majora. 

The  superficial  perineal  branch  passes  between  the  constrictor  muscle  and  the  bulb  of 
the  vagina,  and  then  terminates  in  these  parts. 

,  The  internal  pudic  nerve  in  the  female  does  not  appear  to  me  to  be  half  the  size  of  the 
internal  pudic  nerve  of  the  male.  In  one  case  I  found  that  it  consisted  only  of  the  branch 
for  the  clitoris,  the  superficial  branch  being  supplied  by  the  inferior  gluteal  nerve. 

The  Superior  Gluteal  JSTerve. 
The  superior  gluteal  nerve,  which  is  intended  for  the  glutaeus  medius  and  minimus,  and 
the  tensor  vaginae  femoris,  arises  from  the  back  of  the  lumbo-sacral  trunk,  before  its 
junction  with  the  first  sacral  nerve.  I  have  seen  it  arising  by  two  roots,  of  which  one 
came  from  the  lumbo-sacral  nerve  and  the  other  from  the  posterior  surface  of  the  plex- 
us :  it  emerges  from  the  pelvis  (a,  fig.  293)  by  the  upper  and  fore  part  of  the  great  sci- 
atic notch,  in  front  of  the  pyriformis,  is  reflected  upon  this  notch  to  pass  between  the 
glutaeus  medius  and  minimus,  and  divides  into  two  branches ;  the  one  ascending,  which  en- 
circles the  origin  of  the  glutaeus  minimus,  like  the  corresponding  branch  of  the  gluteal  ar- 
tery ;  and  the  other  descending,  which  passes  obliquely  downward  and  outward,  between, 
the  glutaeus  medius  and  minimus,  to  which  it  gives  off  numerous  filaments,  and  thus,  grad- 
ually diminished  in  size,  it  embraces,  as  it  were,  the  posterior  surface  of  the  glutaeus  min- 
imus, and  having  reached  the  external  border  of  that  muscle,  it  passes  downward,  and 
enters  the  sheath  of  the  tensor  vaginae  femoris,  in  which  it  terminates.  Before  entering 
the  sheath  of  the  tensor  vaginae  it  gives  off  a  remarkable  branch,  which  turns  round  the 
anterior  border  of  the  glutaeus  minimus,  and  ramifies  in  that  muscle. 

The  JVervefor  the  Pyriformis. 
This  little  nerve  arises  separately  from  the  posterior  surface  of  the  sacral  plexus,  and 
more  particularly  from  the  third  sacral  nerve  ;  it  divides  into  two  branches,  which  im- 
mediately enter  the  anterior  surface  of  the  muscle. 

The  Inferior  Gluteal  JVerve.  > 

The  inferior  gluteal  nerve  (Bichat),  or  the  lesser  sciatic  nerve  {Boyer),  is  intended  for  the 
glutaeus  maximus,  the  integuments  of  the  posterior  region  of  the  thigh,  and  for  a  part  of 
the  skin  of  the  leg.  It  arises  from  the  back  of  the  sacral  plexus,  sometimes  by  one 
cord,  sometimes  by  several  very  distinct  cords.  It  emerges  from  the  pelvis  (near  c,fig. 
293),  below  the  pyriformis,  together  with  and  on  the  inner  side  of  the  great  sciatic  nerve, 
to  which  it  may  be  regarded  as  an  accessory  ;  it  passes  behind  that  nerve,  and  divides 
into  two  sets  of  branches,  viz.,  muscular  and  cutaneous. 

The  muscular  branches  (c)  are  numerous,  although  exclusively  intended  for  the  glutaeus 
maximus  ;  they  divide  into  ascending  and  external  branches,  which  run  along  the  ante- 


808  NEUROLOGY. 

rior  surface  of  the  muscle,  spread  out  upon  it,  and  may  be  traced  as  far  as  its  upper  oor- 
der,  and  descending  and  internal  branches,  which  pass  between  the  tuberosity  of  the  is- 
chium and  the  muscle,  and  then  enter  the  latter. 

The  cutaneous  branch  (b)  continues  in  the  original  course  of  the  nerve,  behind  the  great 
sciatic,  and  in  front  of  the  glutajus  maximus ;  it  crosses  obliquely,  downward  and  in- 
ward, over  the  tuberosity  of  the  ischium  and  the  origins  of  the  biceps  and  senii-tendi- 
nosus  muscles  ;  considerably  reduced  in  size,  from  having  given  off  several  branches,  it 
assumes  the  name  of  lesser  sciatic  (/),  runs  vertically  downward,  becoming  smaller  and 
smaller,  and  may  be  traced  down  to  the  posterior  region  of  the  leg. 

The  cutaneous  branch,  as  it  emerges  from  the  glutaeus  maximus,  gives  off  a  consid- 
erable recurrent  branch  (e),  which  might  be  regarded  as  a  terminal  branch  of  the  nerve. 
This  branch  is  reflected  upward  so  as  to  describe  a  curve  having  its  concavity  turned 
upward,  and  subdivides  into  two  secondary  branches,  an  internal  and  an  external :  the 
external  branch  is  the  larger,  and  ramifies  in  the  skin  of  the  gluteal  region  ;  the  internal 
or  scrotal  branch  (pudendalis  longus  inferior,  Sammering)  is  a  very  remarkable  one  ;  it  is 
reflected  forward  upon  the  under  surface  of  the  tuberosity  of  the  ischium,  runs  along  at 
some  distance  from  the  ascending  ramus  of  the  ischium  and  the  descending  ramus  ot 
the  OS  pubis,  anastomoses  with  the  superficial  perineal  nerve,  reaches  the  scrotum  above 
the  testis,  and  divides  into  two  branches — an  external,  which  passes  on  the  outer  side, 
and  an  internal,  which  runs  on  the  inner  side  of  the  testis  ;  having  embraced  this  organ, 
they  are  distributed  to  the  skin  of  the  anterior  part  of  the  scrotum  and  the  lower  part  oi 
the  penis.     In  the  female,  this  branch  belongs  to  the  labia  majora. 

All  along  the  thigh,  the  cutaneous  branch  of  the  inferior  gluteal  nerve  gives  off  some 
very  small  external  branches,  and  some  larger  internal  branches,  which  are  reflected 
forward,  describing  curves  having  the  concavity  turned  upward,  and  supply  the  skin  of 
the  internal  region  of  the  thigh. 

In  the  pophteal  space,  the  cutaneous  branch  divides  into  two  filaments,  one  sub-cuta- 
neous, which  may  be  traced,  notwithstanding  its  extreme  tenuity,  as  far  as  the  middle  of 
the  posterior  region  of  the  leg  ;  and  the  other  sub-aponeurotic,  which  perforates  the  fas- 
cia of  the  leg,  runs  along  the  external  saphenous  vein,  and  anostomoses  with  the  exter- 
nal saphenous  nerve. 

The  Jferves  for  the  Quadratus  Femoris  and  the  Gemelli. 

The  superior  gemellus  receives  a  special  nerve  from  the  anterior  part  of  the  sacral  plexus. 
The  nerve  for  the  inferior  gemellus  is  a  branch  of  the  nerve  for  the  quadratus  femoris. 

The  nerve  for  the  quadratus  femoris  is  remarkable.  It  arises  from  the  front  of  the  sa- 
cral plexus,  or,  rather,  from  the  limit  between  this  plexus  and  the  great  sciatic  nerve, 
passes  vertically  downward  in  front  of  the  gemelli  and  obturator  internus,  by  which  it  is 
separated  from  the  great  sciatic  nerve,  and  it  is  placed  in  contact  with  the  os  innomi- 
natum,  to  the  outer  side  of  the  tuberosity  of  the  ischium.  It  gives  off  some  external  pe- 
riosteal and  osseous  branches,  which  enter  the  foramina  in  the  tuberosity  of  the  ischium ; 
some  internal  or  articular  branches,  which  perforate  the  fibrous  capsule  of  the  hip-joint ; 
a  branch  for  the  inferior  gemellus  ;  and  then  terminates  in  the  quadratus  femoris,  which 
it  enters  by  its  anterior  surface. 

The  Terminal  Branch  of  the  Sacral  Plexus,  or  the  Great  Sciatic  Nerve. 

The  great  sciatic  nerve  (grand  femoro-poplite,  Chauss.)  is  intended  for  the  muscles  of 
the  posterior  region  of  the  thigh,  and  for  the  muscles  and  integuments  of  the  leg  and 
foot :  it  is  the  termination  (s,  fig.  290)  of  the  sacral  plexus,  or,  rather,  it  is  the  sacral 
plexus  itself  condensed  into  a  nervous  cord.  The  fifth  lumbar  nerve,  a  branch  of  the 
fourth  lumbar,  the  three  superior  sacral  nerves,  and  a  branch  from  the  fourth,  form  the 
origins  of  this  great  nerve,  which  is  the  largest  in  the  body. 

It  emerges  from  the  pelvis,  through  the  great  sciatic  notch,  below  the  pyriformis  im- 
mediately above  the  spine  of  the  ischium,  passes  vertically  downward  (s,  fig.  293)  be- 
tween the  tuberosity  of  the  ischium  and  the  great  trochanter,  both  of  which  project  so 
as  to  separate  it  from  the  skin,  or,  more  exactly,  it  runs  along  the  outer  side  of  the  tu- 
berosity of  the  ischium,  in  a  very  deep  groove  between  that  process  and  the  margin  of 
the  cotyloid  cavity.  At  its  exit  from  the  pelvis,  it  is  a  flat,  riband-shaped  nerve,  six 
lines  in  breadth,  but  it  soon  becomes  rounded,  runs  vertically  downward  along  the  back 
of  the  thigh,  sloping,  however,  a  little  outward  ;  having  arrived  about  three  or  four  fin- 
gers' breadth  above  the  knee-joint,  it  divides  into  two  branches,  which  are  called  the 
external  popliteal  sciatic  or  the  peroneal  nerve  (i),  and  the  internal  popliteal  sciatic  or  tibial 
nerve  (A). 

The  sciatic  nerve  sometimes  divides  at  its  exit  from  the  pelvis,  but  it  may  do  so  at 
any  other  point  between  that  and  the  popliteal  space.  This  premature  division  is  of 
no  importance  ;  in  fact,  it  always  exists  ;  for  when  there  is  apparently  only  one  trunk, 
the  two  branches  of  the  bifurcation  are  perfectly  distinct  through  the  whole  length  of 
ihe  thigh,  and  are  merely  in  contact  with  each  other.* 

*  When  the  great  sciatic  nerve  divides  within  the  pelvis,  the  upper  division  perforates  the  pyriformis,  while 
'He  lower  emerges  from  below  that  muscle. 


THE  GREAT   SCIATIC    NERVE,   ETC. 


809 


Relations. — Behind.,  the  great  sciatic  nerve  is  covered  by  the  Fig.  293. 

glutaeus  maximus,  and  then  by  the  long  head  of  the  biceps  and 
the  semi-tendinosus  ;  lower  down  it  occupies  the  cellular  inter- 
val between  these  two  last-named  muscles,  and  when  they  sep- 
arate from  each  other  to  form  the  borders  of  the  popliteal  space, 
it  becomes  sub-aponeurotic. 

In  front,  it  corresponds  to  the  gemelli  and  obturator  internus, 
by  which  it  is  separated  from  the  os  coxffi,  to  the  quadratus  femo- 
ris  and  the  adductor  magnus.  During  its  course  it  is  surround- 
ed by  a  large  quantity  of  adipose  cellular  tissue,  but  has  no  ac- 
companying vessel.* 

Collateral  Branches  of  the  Cheat  Sciatic. — The  great  sciatic 
nerve  gives  off  in  the  thigh  five  muscular  and  three  articular 
branches  ;  they  sometimes  arise  separately,  sometimes  by  a 
common  trunk.     They  are  the  following  : 

The  nerve  for  the  long  head  of  the  biceps,  which  divides  into  two 
ascending  branches  for  the  origin  of  that  muscle  from  the  ischium, 
and  descending  branches,  which  run  for  a  long  time  in  front  of  the 
muscle,  and  then  enter  it  by  a  series  of  filaments. 

The  nerve  for  the  semi-tendinosus,  which  runs  upon  the  anterior 
surface  of  the  muscle,  and  does  not  enter  it  until  it  reaches  the 
lower  third  of  the  thigh. 

The  nerves  for  the  semi-membranosus  are  two  in  number  ;  they 
almost  always  anastomose  and  enter  the  internal  surface  of  the 
muscle  at  two  different  points. 

A  nerve  for  the  adductor  magnus,  which  runs  forward  and  then 
inward,  and  enters  near  the  inner  border  of  the  muscle.  We 
have  seen  that  the  adductor  magnus  receives  most  of  its  nerves 
from  the  obturator  nerve.  All  the  preceding  branches  arise  from 
the  upper  part  of  the  sciatic  nerve,  opposite  to  the  quadratus  femo- 
ris,  and  often  by  a  common  trunk. 

A  nerve  for  the  short  head  of  the  biceps  sometimes  arises  at  the 
same  height  as  the  preceding,  but  is  most  commonly  given  off 
from  the  sciatic  nerve  at  the  middle  of  the  thigh.  When  the  sci- 
atic nerve  divides  prematurely,  the  branch  we  are  now  descri- 
bing comes  from  the  external  popliteal.  This  nerve  enters  the 
upper  extremity  of  the  muscle,  expanding  into  diverging  fila- 
ments. 

An  articular  nerve  of  the  knee,  which  often  arises  by  a  common 
trunk  with  the  preceding,  and  is  not  unfrequently  given  off  from 
the  external  popliteal ;  it  passes  vertically  downward  in  front  of 
the  great  sciatic  nerve,  through  some  adipose  tissue,  to  gain  the 
outer  side  of  the  joint ;  having  arrived  above  the  external  con- 
dyle, it  turns  and  divides  into  several  filaments,  which  perforate 
the  fibrous  tissue  of  the  joint,  and  are  distributed  to  the  articular 
adipose  tissue,  where  they  are  scattered,  some  above,  others  be- 
low, and  others  on  the  outer  side  of  the  patella,  t 

The  External  Popliteal  Sciatic  or  Peroneal  J^erve. 

The  external  popliteal  sciatic,  external  popliteal,  or  peroneal  nerve 
{i,fig.  293),  the  external  terminal  branch  of  the  great  sciatic,  is 
intended  for  all  the  muscles  of  the  anterior  and  external  region  of 
the  leg,  and  for  the  skin  on  the  leg  and  on  the  dorsum  of  the  foot. 
It  is  scarcely  half  the  size  of  the  internal  popliteal ;  it  runs  obliquely  downward  and  out- 
ward, behind  the  external  condyle  of  the  femur  through  the  popliteal  space,  and  is  pla- 
ced nearer  to  the  surface  than  the  internal  popliteal  nerve,  which  is  lodged  in  the  inter- 
condyloid  fossa  ;  it  then  crosses  obliquely  over  the  origin  of  the  outer  head  of  the  gas- 
trocnemius, passes  behind  the  head  of  the  fibula,  from  which  it  is  separated  by  the  ori- 
gin of  the  soleus,  turns  horizontally  upon  the  neck  of  that  bone  (at  v),  between  it  and  the 
peroneus  longus,  and  expands  into  four  branches,  two  superior  or  recurrent,  for  the  tib- 
ialis anticus,  and  two  inferior  and  larger,  which  form  the  true  terminations  of  the  nerve. 

Collateral  Branches. 
During  this  course,  the  external  popliteal  nerve  gives  off  two  superficial  collateral 

*  In  three  instances  I  have  found  the  great  sciatic  accompanied  by  a  large  vein,  which  was  continuous  with 
the  popliteal  vein,  and  perforated  the  upper  part  of  the  adductor  magnus,  like  the  profunda  artery.  In  two  of 
these  cases  the  sciati*  nerve  divided  at  its  exit  from  the  pelvis.  I  did  not  note  the  arrangement  of  the  nerve 
in  the  third  case.  It  was  a  remarkable  circumstance  that  there  was  another  popliteal  vein  accompanying  the 
artery  :  in  one  of  the  cases  the  vein  was  in  front  instead  of  behind  the  artery.  t  See  note,  p.  812. 

5K 


810  NEUROLOGY. 

nerves  :  a  saphenous  nerve,  which  we  shall  call  the  peroneal  saphenous^  to  distinguish  it 
from  the  tibial  saphenous,  and  the  peroneal  cutaneous  branch. 

The  Peroneal  Saphenous  Nerve. 

The  peroneal  saphenous  nerve  {n)  presents  many  varieties  in  different  subjects,  both  in 
regard  to  its  size  and  origin.  It  is  generally  smaller  than  the  tibial  saphenous  (/),  of 
which  it  may  be  regarded  as  an  accessory ;  it  arises  in  the  popliteal  space,  descends 
vertically  beneath  the  fascia,  between  the  external  and  internal  popliteal  nerves,  perfo- 
rates the  fascia  opposite  the  middle  of  the  leg,  to  join  the  external  saphenous  vein, 
with  which  it  runs  along  the  tendo  Achillis,  and  terminates  upon  the  outer  side  of  the 
OS  calcis.  During  this  course,  it  gives  off"  several  cutaneous  filaments  and  a  communi- 
cating branch  to  the  tibial  saphenous  nerve :  this  branch  is  of  considerable  size,  and 
comes  off"  while  the  nerve  is  still  beneath  the  fascia.  Having  become  very  slender  after 
giving  these  branches,  the  peroneal  saphenous  nerve  subdivides  opposite  the  lower  part 
of  the  tendo  Achillis,  and  upon  the  outer  side  of  the  os  calcis,  into  several  calcaneal 
branches,  one  of  which  turns  obliquely  round  the  posterior  surface  of  the  os  calcis,  while 
the  others  descend  vertically,  are  reflected  upon  the  under  surface  of  that  bo^e,  and  are 
distributed  to  the  skin  of  the  heel.  Not  unfrequently  the  peroneal  saphenous  nerve  gives 
off  a  malleolar  branch,  which  passes  between  the  external  malleolus  and  the  skin,  and 
anastomoses  in  front  of  the  ankle-joint  {y,fig.  291)  with  a  twig  from  the  muscuJo-cuta- 
neous  nerve.  This  malleolar  branch,  which  often  comes  from  the  last-mentioned  nerve, 
is,  moreover,  remarkable,  like  all  nerves  which  are  subjected  to  strong  pressure,  for  its 
thickness,  its  grayish  colour,  and,  lastly,  for  its  knotted,  and,  as  it  were,  ganglionated 
appearance. 

The  peroneal  saphenous  nerve  is  often  very  small,  and  is  lost  in  the  skin  upon  the 
middle  of  the  leg  :  its  place  is  then  supplied  in  the  lower  two  thirds  of  the  leg  by  the  tib- 
ial saphenous  nerve,  the  size  of  which  is  always  in  an  inverse  ratio  to  that  of  the  pero- 
neal saphenous. 

No  nerve  presents  more  varieties  than  the  peroneal  saphenous ;  they  relate  to  its  size 
and  to  the  point  at  which  it  anastomoses  with  the  tibial  saphenous.  One  of  the  most 
remarkable  varieties  is  that  in  which  the  peroneal  and  tibial  saphenous  nerves,  those  call- 
ed communicating  saphenous  branches  {communicans  fibula,  n;  communicans  tibia,  I)  unite 
in  the  popliteal  space  into  a  single  trunk,  the  external  saphenous  {p),  the  distribution  of 
which  corresponds  to  the  ordinary  distribution  of  the  two  nerves. 

The  Peroneal  Cutaneous  Branch. 
This  comes  off  from  the  external  popliteal  nerve,  behind  the  outer  condyle  of  the  fe- 
mur, passes  vertically  downward  along  the  fibula,  in  contact  with  the  skin,  and  divides 
into  ascending  and  descending  branches,  the  latter  of  which  may  be  traced  as  far  as  the 
lower  part  of  the  leg. 

The  Terminal  Branches  of  the  External  Popliteal  J^erve. 
The  Branches  for  the  Tibialis  Anticus. 

The  two  superior  or  recurrent  branches,  resulting  from  the  subdivision  of  the  external 
popliteal,  pass  horizontally  inward,  behind  the  extensor  communis  digitorum,  and  are 
distributed  to  the  tibialis  anticus  ;  one  of  these  branches  supplies  the  peroneo-tibial  ar- 
ticulation. 

The  Musculo-cutaneous  Branch,  or  External  Peroneal  Nerve 

The  musculo-cutaneous  branch  {x,fig.  291),  the  lowest  of  the  terminal  branches  of  the 
external  popliteal,  is  intended  for  the  muscles  of  the  externail  region  of  the  leg,  and  for 
the  skin  upon  the  dorsum  of  the  foot  (pretibio-digital,  Chauss. ;  peroneus  externus,  Saemm.). 

It  passes  at  first  obliquely,  then  vertically  downward  in  the  substance  of  the  peroneus 
longus,  turns  forward  to  enter  between  the  extensor  longus  digitorum  and  the  peroneus 
longus  and  brevis,  and  perforates  the  fascia  of  the  leg,  above  the  ankle-joint :  having 
thus  become  sub-cutaneous,  it  passes  obliquely  downward  and  inward,  following  the  di- 
rection of  the  extensor  longus  digitorum,  becomes  flattened  and  widened,  and  divides  a 
little  below  the  tibio-tarsal  articulation  into  an  internal  and  an  external  branch  ;  the  lat- 
ter subdivides  into  three  other  branches,  so  that  there  are  in  all  four  terminal  branches, 
which  form  the  dorsal  collateral  nerves  of  the  toes. 

Not  unfrequently  the  musculo-cutaneous  nerve  bifurcates  as  it  escapes  from  beneath 
the  fascia  of  the  leg,  and  its  two  branches  reunite  opposite  to  the  tibio-tarsal  articula- 
tion, so  as  to  describe  an  elongated  ellipse. 

Collateral  Branches. — There  are  two  branches  for  the  peroneus  longus,  of  which  one 
comes  off  from  the  nerve  immediately  after  its  origin,  while  the  other  arises  lower  down, 
and  runs  a  very  long  course  in  the  substance  of  the  muscle  ;  there  is  also  a  branch  for 
the  peroneus  brevis,' which  often  arises  by  a  common  trunk  with  the  preceding. 

In  its  sub-cutaneous  portion,  the  musculo-cutaneous  nerve  supplies  several  filaments 
to  the  skin,  among  which  we  should  distinguish  an  external  malleolar  filament,  which  passes 
between  the  external  malleolus  and  the  skin,  increases  considerably  in  size,  and  becomes 


THE    ANTERIOR   TIBIAL   NERVE,  ETC.  811 

grayish  and  knotted,  like  all  nerves  subjected  to  pressure.  This  filament  often  anastomo- 
ses with  the  malleolar  branch  of  the  peroneal  saphenous  nerve,  and  sometimes  supphes 
the  place  of  that  malleolar  branch. 

Terminal  Branches. — There  are  four  terminal  branches  of  the  musculo-cutaneous  nerve, 
distinguished  numerically  as  the  first,  second,  third,  and  fourth  (see^^.  291).  The^r«( 
or  internal  branch  passes  very  obliquely  forward  and  inward,  to  form  the  internal  dorsal 
collateral  nerve  of  the  great  toe ;  this  nerve,  like  all  nerves  subjected  to  pressure,  increas- 
es in  size  and  becomes  grayish,  and,  as  it  were,  knotted  opposite  the  metatarso-phalan- 
gal  articulation.  The  second  branch,  which  often  arises  by  a  common  trunk  with  the 
first,  supplies  the  external  dorsal  collateral  nerve  of  the  great  toe,  and  the  internal  collateral 
nerve  of  the  second  toe.  The  third  branch  supplies  the  external  collateral  nerve  of  the  sec- 
ond, and  the  internal  collateral  nerve  of  the  third  toe.  These  two  large  branches  are 
often  replaced  by  one  (»)  from  the  anterior  tibial  nerve,  with  which  they  anastomose. 
The  fourth  terminal  branch  or  internal  branch  supplies  the  external  dorsal  collateral  nerve 
of  the  third,  and  the  internal  dorsal  collateral  nerve  of  the  fourth  toe. 

All  the  filaments  from  these  branches  are  distributed  to  the  skin  upon  the  dorsal  re- 
gion of  the  foot  and  digital  phalanges. 

In  a  great  number  of  subjects,  the  tibial  or  external  saphenous  nerve  supplies  the  in- 
ternal collateral  nerve  of  the  little  toe,  and  the  external  collateral  nerve  of  the  fourth 
toe  ;  but  in  others,  these  nerves  are  furnished  by  an  additional  terminal  branch  of  the 
mosculo-cutaneous  nerve  ;  in  all  cases  the  nerves  anastomose  with  each  other. 

The  Anterior  Tibial,  or  Interosseous  Nerve. 

The  anterior  tibial  or  interosseous  nerve  (v  v,fig.  291),  intended  for  the  muscles  on  the 
anterior  region  of  the  leg,  for  the  extensor  brevis  digitorum,  and  for  the  interosseous 
muscles  in  the  foot,  is  as  large  as  the  musculo-cutaneous  nerve  just  described ;  it  runs 
to  the  inner  side  of  that  nerve,  beneath  the  extensor  communis  digitorum,  and  passes 
along  the  interosseous  ligament,  together  with  the  anterior  tibial  artery  lying  in  front  of 
that  vessel.  It  is  placed,  like  the  artery,  between  the  tibialis  anticus  and  the  extensor 
communis  digitorum,  from  which  it  is  separated  below  by  the  extensor  proprius  pollicis 
pedis  ;  it  supplies  a  great  number  of  filaments  to  all  these  muscles,  passes  with  the  ar- 
tery under  the  annular  ligament  of  the  tarsus,  in  the  sheath  of  the  extensor  proprius  pol- 
licis, and  divides  into  two  branches  : 

The  internal  deep  branch  of  the  dorsum  of  the  foot  (v),  which  is  the  true  continuation  of 
the  nerve,  passes  horizontally  forward,  under  the  arteria  dorsalis  pedis,  over  the  first  in- 
terosseous space,  gives  off  a  small  twig  to  the  muscles  of  that  space,  and  divides  into 
two  branches,  which  form  the  deep  external  dorsal  collateral  nerve  of  the  great  toe,  and  the 
internal  dorsal  collateral  nerve  of  the  second  toe.  These  branches  communicate  with  the 
superficial  dorsal  branches  of  the  musculo-cutaneous  nerve,  and  sometimes  supply  their 
place. 

The  external  and  deep  nerve  of  the  dorsum  of  the  foot  runs  outward  between  the  tarsus 
and  the  extensor  brevis  digitorum,  in  which  it  terminates ;  it  gives  off  in  front,  opposite 
the  interosseous  spaces,  a  series  of  very  delicate  filaments,  which  enter  the  posterior 
extremities  of  those  spaces.  The  filaments  for  the  fourth  and  fifth  spaces  often  arise 
by  a  common  trunk.    They  are  extremely  delicate,  and  are  closely  applied  to  the  tarsus. 

The  Internal  Popliteal  Sciatic^  or  Tibial  JVerve. 

The  internal  popliteal  sciatic,  internal  popliteal,  or  tibial  nerve  (h,  fig.  293),  is  intended 
for  all  the  muscles  of  the  back  of  the  leg,  and  for  the  skin  of  the  sole  of  the  foot ;  both 
in  direction  and  size  it  appears  to  be  the  continuation  of  the  great  sciatic  nerve.  It  pass- 
es vertically  downward  in  the  inter-condyloid  fossa  of  the  femur ;  it  is  at  first  placed  be- 
tween the  heads  of  the  gastrocnemius,  it  then  passes  under  that  muscle  and  under  the 
arch  formed  by  the  soleus,  descends,  under  the  name  of  the  posterior  tibial  nerve  {k),  be- 
tween the  soleus  and  the  deep  layer  of  muscles,  inchnes  a  little  inward,  and,  having 
reached  the  termination  of  the  fleshy  belly  of  the  soleus,  gains  the  inner  side  of  the  ten- 
do  Achillis  ;  lower  down,  it  passes  behind  the  internal  malleolus,  against  which  it  is  flat- 
tened and  widened,  and  divides  into  the  internal  and  external  plantar  nerves  (a,  b,  and  c, 
/«■•  294). 

In  the  popliteal  space  it  is  sub-aponeurotic,  in  the  fleshy  portion  of  the  leg  it  is  sep- 
arated from  the  fascia  by  the  double  layer  formed  by  the  gastrocnemius  and  the  soleus, 
and  it  again  becomes  sub-aponeiirotic  along  the  tendo  Achillis.  It  is  in  relation,  in 
front,  with  the  popliteal  and  posterior  tibial  vessels,  which  separate  it,  above,  from  the 
knee-joint  and  popliteus  muscle,  and  lower  down,  from  the  deep  layer  of  muscles  in  the 
leg.*  Behind  the  internal  malleolus,  and  under  the  groove  upon  the  os  calcis,  it  is  en- 
closed in  a  common  fibrous  sheath  with  the  posterior  tibial  vessels,  which  are  placed  in 
front  of  it ;  this  sheath  is  behind  that  for  the  tendons  of  the  tibiahs  posticus  and  flexor 
communis  digitorum. 

*  [The  nerve  is  at  first  at  a  short  distance  to  the  outer  sid«  of  the  artery  ;  lower  down  it  lies  immediately 
behind  the  vessel,  and  still  lower  croises  to  the  imier  side  of  the  artery,  and  is  separated  from  it  by  the  vein.] 


NEXJEOLOGY. 

Its  coilaieral  'IfrancMs  are  very  numerous.  I  shall  div'de  them  info  Itliose  ^ven'ra^dp- 
posite  the  knee-joint,  and  those  supplied  along  the  leg. 

The  Collateral  Branches  of  the  Internal  Popliteal  Jferve,  behind  the  Knee- Joint. 

These  are  six  in  number,  namcl}',  two  anterior,  which  are  very  small,  one  for  the 
plantaris  longus,  and  one  for  the  knee-joint ;  two  internal,  namely,  the  tibial  saphenous 
nerve,  and  the  nerve  for  the  inner  head  of  the  gastrocnemius  ;  two  external,  namely,  the 
nerve  for  the  outer  head  of  the  gastrocnemius,  and  the  nerve  for  the  soleus. 
The  Tibial  Saphenous  Nerve. 

This  is  generally  known  as  the  external  saphenous.  It  is  much  larger  than  the  pero- 
neal saphenous,  which  always  anastomoses  with  it.  I  have  already  said  that  the  mode 
and  situation  of  this  anastomosis  present  many  varieties.  The  tibial  saphenous  nerve 
{communicant  tibia,  I,  Jig.  293)  arises  in  the  popliteal  space,  passes  vertically  downward 
between  the  two  heads  of  the  gastrocnemius,  and  then  upon  their  posterior  surface, 
along  their  fibrous  septum,  between  them  ;  it  is  here  situated  in  a  small  fibrous  canal 
common  to  it  and  to  a  small  artery  and  vein  ;  it  receives,  at  a  variable  height  in  the  leg, 
a  more  or  less  considerable  filament  from  the  peroneal  saphenous  nerve  (or  communicans 
fibulce,  n) ;  it  then  becomes  sub-cutaneous,  forming  the  external  saphenous  nerve  (p), 
runs  along  the  outer  side  of  the  tendo  Achillis,  just  as  the  posterior  tibial  runs  along  its 
inner  side ;  it  now  accompanies  the  external  saphenous  vein,  which  is  accompanied 
above  this  point  by  the  peroneal  saphenous  nerve ;  it  is  reflected  behind  the  external 
malleolus,  in  the  same  manner  as  the  tibial  nerve  is  reflected  upon  the  internal  malleolus, 
then  runs  forward  and  downward  {y,fig.  291)  upon  the  outer  side  of  the  os  calcis,  where 
it  gives  off  several  very  large  external  calcaneal  nerves,  and  terminates  difTerently  in  va- 
rious subjects.  In  some  it  terminates  by  forming  the  dorsal  collateral  nerve  of  the  fifth  • 
toe ;  in  others  it  is  larger,  and  divides  into  two  branches,  of  which  the  external  forms  the 
external  collateral  nerve  of  the  fifth  toe,  while  the  internal,  which  receives  an  anasto- 
motic branch  from  the  musculo-cutaneous  nerve  (z),  passes  horizontally  forward,  crosses 
the  extensor  brevis  digitorum,  and  the  tendons  of  the  long  extensors,  and  divides  into 
two  secondary  branches,  of  which  one  constitutes  the  internal  dorsal  collateral  nerve  of 
the  little  toe,  and  the  other  the  external  dorsal  collateral  nerve  of  the  fourth  toe.  I  may 
point  out  the  thickening,  the  gray  colour,  and  the  knotted,  and,  as  it  were,  ganglionated 
structure  of  the  external  collateral  nerve  of  the  little  toe  opposite  to  the  articulations. 

The  cxtertMl  calcaneal  nerves,  which  may  be  regarded  as  forming  the  termination  of 
the  tibial  saphenous,  are  very  remarkable  ;  they  pass  vertically  along  the  outer  side  of 
the  OS  calcis,  expand  into  several  filaments,  which  are  reflected  upon  the  ridge  which 
separates  the  external  from  the  inferior  surface  of  that  bone,  and  are  distributed  to  the 
skin  upon  the  heel. 

During  its  course  along  the  leg,  the  tibial  saphenous  gives  off  scarcely  a  single  fila- 
ment, but  along  the  outer  border  of  the  foot  it  supplies  a  great  number,  which  run  down- 
ward and  forward,  and  terminate  in  the  skin  covering  the  external  plantar  region. 

The  size  of  the  tibial  saphenous  nerve  is  inversely  proportioned  to  that  of  the  pero- 
neal saphenous  and  musculo-cutaneous  nerves.  Thus,  when  the  peroneal  saphenous 
nerve  is  large,  it  furnishes  most  of  the  external  calcaneal  branches  ;  and  when  the  mus- 
culo-cutaneous nerve  is  large,  it  supplies,  besides  the  external  calcaneal,  the  internal 
dorsal  collateral  nerve  of  the  little  toe,  and  the  external  dorsal  collateral  nerve  of  the 
fourth  toe. 

The  Nerves  for  the  two  Heads  of  the  Gastrocnemius  and  for  the  Soleus. 

The  nerve  for  the  inner  head  of  the  gastrocnemius  often  arises  by  a  common  trunk 
with  the  tibial  saphenous ;  again,  the  nerves  for  the  outer  head  of  the  gastrocneniius 
and  for  the  soleus  often  arise  by  a  common  trunk  :  the  nerves  for  the  gastrocnemius  en- 
ter the  anterior  surface  of  the  head  of  that  muscle,  and  immediately  ramify.  The  nerve 
for  the  soleus  is  the  largest,  and  enters  the  muscle  at  its  upper  arch  ;  all  these  nerves 
ramify  as  soon  as  they  enter  the  muscles  which  they  supply. 

The  Articular  Nerve  and  Nerve  for  the  Plantaris  Longus. 

The  posterior  articular  nerve  of  the  knee  runs  forward  to  enter  the  posterior  ligament 
of  the  articulation  :  one  of  its  filaments  follows  the  direction  of  the  internal  articular  ar- 
tery, and  is  lost  in  the  popliteus.* 

*  [From  the  dissections  of  Mr.  EUjs,  it  appears  that  there  is  an  articular  nerve  to  the  knee-joint  with  each 
articular  artery.  The  superior  external  articular  nerve  is  the  one  described  at  p.  809 ;  it  most  commonly 
arises  from  the  extertial  popliteal.  The  inferior  external  articular  also  arises  from  the  external  popliteal,  and 
sometimes  from  the  ioiatic  nerve  ;  it  is  a  long  branch  which  descends  towards  the  external  condyle,  passes  be- 
low it  on  the  outer  side  of  the  joint,  and  perforates  the  capsule.  The  superior  internal  articular  is  very  small, 
and  is  not  constant ;  it  arises  from  the  internal  popliteal  nerve,  and  passes  on  the  outer  side,  and  then  in  front 
of  (t.  e.,  deeper  than)  the  popliteal  vessels,  and  reaches  with  its  artery  the  inner  side  of  the  joint.  The  infe- 
rior internal  articular  is  the  largest  of  all :  it  arises  from  the  internal  jiopliteal  above  the  joint,  descends  on  the 
outer  side,  and  then  in  front  of  the  popliteal  vessels,  is  applied  to  the  corresponding  artery  upon  the  popliteus 
muscle,  passes  beneath  the  mternal  lateral  ligament,  and  enters  the  inner  side  of  tlie  joint.  The  posterior  ar- 
ticular, or  azygos,  is  given  off  opposite  the  joint  from  the  internal  popliteal,  or  from  the  inferior  internal  ar- 
ticular ;  it  perforates  the  postferior  ligament. — {Ellis's  Demonstrations  of  Anatomy,  p.  675,  67(1.)] 


THE  INTERNAL  PLANTAR  NERVE. 


813 


Tlie  nerve  for  the  ■plantaris  longus  always  arises  separately  from  the  posterior  tibial 
nerve,  and  immediately  dips  into  the  substance  of  the  muscle. 

Collateral  Branches  of  the  Internal  Popliteal  Jferve  in  the  Leg. 

There  are  three  sets  of  collateral  branches  given  off  by  the  posterior  tibial  nerve  in 
the  leg:  namely,  the  nerve  for  the  popliteus  ;  the  nerves  for  the  deep  layer  of  muscles  ; 
the  internal  calcaneal  nerve.  Lastly,  several  very  small  filaments  come  off  from  the 
nerve,  run  along  the  posterior  tibial  artery,  and,  after  a  course  of  variable  length,  perfo- 
rate the  aponeurosis  and  ramify  in  the  skin. 

The  nerve  for  the  popliteus  arises  opposite  the  knee-joint,  runs  forward  on  the  outer 
side  of  the  popliteal  vessels  to  gain  the  lower  border  of  the  muscle,  around  which  it 
#  turns  ;  before  entering  the  muscle,  the  nerve  expands  into  several  branches,  all  of 
which  pass  horizontally  forward  opposite  to  the  interosseous  ligament,  which  they  ap- 
pear to  perforate.  But  with  a  little  care  it  is  seen  that  almost  all  of  these  filaments  are 
lost  in  the  muscle.  I  have,  however,  seen  one  of  them  perforate  the  interosseous  liga- 
ment together  with  the  anterior  tibial  artery,  and  then,  leaving  that  vessel,  return 
through  the  substance  of  the  ligament,  and  terminate  in  the  tibialis  posticus ;  several 
filaments  of  the  popliteal  nerve  are  also  evidently  distributed  to  the  peroneo-tibial  artic- 
ulation, and  to  the  periosteum  of  the  tibia  and  fibula. 

The  nerves  for  the  deep  layer  of  muscles  of  the  leg  consist  of  two  sets.  The  nerve  for  the 
tibialis  posticus  almost  always  arises  by  a  coimnon  trunk  with  the  preceding,  runs  down- 
ward and  forward,  is  applied  to  the  posterior  surface  of  the  muscle,  to  which  it  gives  a 
series  of  filaments  from  its  anterior  aspect ;  the  continuation  of  the  nerve  enters  the 
muscle  about  its  middle,  and  maybe  traced  in  it  as  far  as  its  lower  part.  The  nerves  for 
the  flexor  longus  pollicis  and  for  the  flexor  communis  arise  by  a  common  trunk  a  little  be- 
low the  preceding ;  the  nerve  for  the  flexor  longus  pollicis,  which  is  larger  than  those 
for  the  flexor  communis  and  tibialis  posticus,  accompanies  the  peroneal  artery  as  far  as 
the  lower  part  of  the  leg. 

The  Internal  Calcaneal  Nerve. — ^This  is  a  large  branch  which  comes  off  from  the  inner 
side  of  the  posterior  tibial  nerve,  and  which,  in  cases  of  premature  bifurcation  of  that 
nerve  into  the  internal  and  external  plantar,  comes  from  the  externeil  plantar ;  it  passes 
vertically  downward,  on  the  inner  side  of  the  os  calcis,  and  divides  into  two  diverging 
branches,  which  are  applied  to  the  inner  side  of  the  bone,  are  reflected  upon  its  lower 
surface,  and  are  distributed  to  the  skin  of  the  heel,  one  in  front,  and  the  other  behind. 

The  Terminal  Branches  of  the  Internal  Popliteal  Jferve. 
The  Internal  Plantar  Nerve. 

The  internal  plantar  nerve,  which  is  intended  for  the  muscles  and  skin  of  the  sole  ol 
the  foot,  is  larger  than  the  external  plantar ;  at  its  origin  it  is  situated  behind  the  inter- 
nal malleolus,  in  front  of  the  posterior  tibial  vessels,  which  cross  it  at  an  acute  angle, 
and  occupies  a  groove  which  is  common  to  it  and  to  those  vessels,  and  which  is  quite 
distinct  from  and  lies  behind  the  groove  for  the  tendons.  It  is  reflected  beneath  the  in- 
ternal malleolus,  becomes  horizontal,  reaches  the  calcaneal  groove,  perforates  the  pos- 
terior extremity  of  the  flexor  brevis  digitorum,  and  during  this  passage  through  the 
groove  is  protected  by  a  fibrous  canal,  which  is  subjacent  to  the  grooves  for  the  tendons. 

At  its  exit  from  this  fibrous  canal,  the  internal  plantar  nerve  is  situated  upon  the 


boundary,  between  the  internal  and  middle  plantar  regions,  between 
the  flexor  brevis  pollicis  on  the  inside,  and  the  flexor  brevis  digi- 
torum on  the  outside  ;  having  given  off  a  considerable  branch  (a, 
fig.  294),  which  becomes  the  internal  plantar  collateral  nerve  of  the 
great  toe,  it  perforates  the  aponeurosis  of  the  flexor  brevis  digitorum 
to  enter  the  same  sheath  as  that  muscle,  and  runs  (J)  along  its  in- 
ner border.  Having  reached  the  posterior  extremity  of  the  meta- 
tarsal bones,  it  divides  into  three  branches,  which  form  the  collateral 
nerves  of  the  toes.  Sometimes  there  is  a  fourth  branch  (d),  which 
passes  outward,  to  anastomose  with  the  external  plantar  nerve. 

The  collateral  branches  are  very  numerous.  Some  of  them  are 
cutaneous,  and  perforate  the  plantar  fascia  to  ramify  in  the  skin. 
The  most  remarkable  are,  a  small  calcaneal  cutaneous  nerve,  which 
crosses  the  posterior  tibial  vessels,  to  supply  the  skin  upon  the  in- 
ner side  of  the  os  calcis ;  and  s.  plantar  cutaneous  nerve,  which  emerges 
between  the  flexor  brevis  pollicis  and  the  flexor  brevis  digitorum, 
and  divides  into  two  small  cutaneous  branches,  one  of  which  pro- 
ceeds forward,  while  the  other  runs  backward,  like  a  recurrent 
nerve.  There  are  cilso  some  muscular  collateral  branches,  namely, 
far  the  flexor  brevis  pollicis,  the  abductor  pollicis,  and  the  flexor  brevis 
digitorum.  Lastly,  the  internal  plantar  collateral  nerve  of  the  great 
toe  {a),  which  is  so  large  that  it  might  be  regarded  as  a  terminal 
branch  of  the  internal  plantar  nerve  ;  it  comes  off  from  the  last- 


Fig.  294. 


I 


814  NEUROLOGY. 

named  nerve,  at  its  exit  from  the  covered  canal  formed  for  it  by  the  flexor  brevis  poUicis, 
passes  forward  along  the  outer  side  of  the  tendon  of  the  flexor  longus  poUicis,  below,  i.  e., 
superficial  to  the  inner  portion  of  the  adductor  poUicis  (oblique  adducteur,  Crnveilhier), 
and  gains  the  inner  and  under  surface  of  the  metatarso-phalangal  articulation  of  the 
great  toe  ;  in  this  place  it  is  situated  in  the  furrow  between  the  internal  and  external 
sesamoid  bones  of  that  articulation  ;  it  runs  forward  below  the  inner  border  of  the  former, 
and  then  of  the  second  phalanx  of  the  great  toe,  and,  having  arrived  below  that  bone,  it 
divides,  like  the  collateral  nerves  of  the  fingers,  into  two  branches,  the  one  dorsal  or  un- 
gual, and  the  other  plantar. 

The  terminal  branches  of  the  internal  plantar  nerve  are  three  in  number,  and  are  distin- 
guished as  the  first,  second,  and  third,  counting  from  within  outward.  i 

The  first  terminal  branch,  which  is  the  largest,  runs  along  the  outer  side  of  the  tendon 
of  the  flexor  longus  poUicis,  gives  filaments  to  that  muscle,  passes  between  the  meta- 
tarso-phalangal articulations  of  the  first  and  second  toes,  under  an  arch  which  is  com- 
mon to  it  and  the  corresponding  vessels,  and  divides  into  two  secondary  branches,  which 
form,  the  external  collateral  nerve  of  the  great  toe,  and  the  internal  collateral  nerve  of  the 
second  toe.  Not  unfrequently  this  branch  gives  an  anastomotic  filament  to  the  internal 
coUateral  nerve  of  the  great  toe,  which  passes  beneath  the  metatarso-phalangal  articu- 
lation of  that  toe. 

The  first  terminal  branch  of  the  internal  plantar  nerve  gives  off  the  filament  for  the 
first  lumbricalis ;  it  then  supplies  several  articular  twigs  to  the  metatarso-phalangal  artic- 
ulation of  the  great  toe,  and  a  very  numerous  series  of  cutaneous  filaments. 

The  second  terminal  branch,  much  smaller  than  the  preceding,  passes  somewhat  out- 
ward, crossing  below,  i.  e.,  superficial  to  the  flexor  tendon  of  the  second  toe,  and  then 
forward,  and  bifurcates  opposite  the  metatarso-phalangal  articulations,  to  constitute  the 
external  plantar  collateral  nerve  of  the  second  toe,  and  the  internal  plantar  collateral  nerve 
of  the  third. 

During  its  course,  this  branch  supplies  filaments  to  the  second  lumbricalis,  to  the  meta- 
tarso-phalangal articulation  of  the  second  toe,  and  also  to  the  integuments. 

The  third  terminal  branch  passes  very  obliquely  outward,  crosses  below  the  flexor 
tendon  of  the  third  toe,  and  bifurcates  to  form  the  external  collateral  nerve  of  the  third  and 
the  internal  collateral  nerve  of  the  fourth  toe. 

This  branch  supplies  the  metatarso-phalangal  articulations  of  the  third  and  fourth  toes, 
and  the  corresponding  integuments. 

Summary. — The  internal  plantar  nerve,  therefore,  supplies  branches  to  the  skin  on  the 
inner  part  of  the  sole  of  the  foot,  also  the  plantar  collateral  nerves  of  the  first,  second, 
and  third  toes,  and  the  internal  collateral  nerve  of  the  fourth  toe,  aU  of  which  are  cu- 
taneous branches. 

It  gives  muscular  branches  to  the  flexor  brevis  poUicis,  the  abductor  poUicis,  the  flexor 
brevis  digitorum,  and  to  the  two  internal  lumbricales. 

Lastly,  it  gives  off  a  great  number  oi  articular  filaments  to  the  tarsal,  tarso-metatarsal, 
metatarso-phalangal,  and  phalangal  articulations. 

The  External  Plantar  Nerve. 

The  external  plantar  nerve  (c,  fig.  294),  which  is  smaller  than  the  internal,  is  placed 
with  it  in  the  groove  of  the  os  calcis,  and  perforates  the  flexor  brevis,  under  an  arch  dis- 
tinct from  that  for  the  internal  plantar,  and  which  is  common  to  it  and  the  external 
plantar  vessels ;  it  then  runs  downward  and  outward,  between  the  flexor  brevis  and  flexor 
accessorius,  is  reflected  forward,  and  divides  into  two  branches,  a  superficial  and  a  deep. 

Collateral  Branches. — During  its  course,  the  external  plantar  nerve  gives  off,  immedi- 
ately after  its  origin,  one  large  branch,  which  runs  horizontally  outward,  in  front  of  the 
tuberosities  of  the  os  calcis,  passes  under  the  flexor  accessorius,  and  is  reflected  for- 
ward to  enter  the  abductor  minimi  digiti.  At  the  point  of  its  reflection,  it  gives  off  a 
transverse  branch,  which  is  lost  in  the  posterior  attachment  of  the  muscle.  The  exter- 
nal plantar  also  supplies  the  nerve  or  nerves  for  the  flexor  accessorius. 

Terminal  Branches. — The  superficial  terminal  branch  (c,  fig.  294),  which  is  the  continu- 
ation of  the  trunk  of  the  nerve,  divides  into  two  others,  one  external,  the  other  internal. 

The  external  branch  passes  very  obliquely  outward,  below  the  flexor  brevis  digiti  min- 
imi, crosses  the  tendon  of  the  abductor  brevis  obliquely,  then  runs  along  the  outer  side 
of  the  fifth  metatarso-phalangal  articulation,  and  forms  the  external  collateral  nerve  of  the 
little  toe.  It  supplies  a  great  number  of  cutaneous  nerves,  also  the  nerves  for  the_^ea;or 
brevis  digiti  minimi,  those  for  the  interosseous  muscles  of  the  fourth  space,  and,  lastly, 
some  articular  filaments. 

The  internal  branch  passes  forward,  below  the  flexor  tendon,  foUowing  the  original  di- 
rection of  the  superficial  branch  of  the  external  plantar,  and,  after  a  rather  long  course, 
bifurcates  to  form  the  internal  collateral  nerve  of  the  little  toe,  and  the  external  collateral 
nerve  of  the  fourth  toe ;  hke  the  external  branch,  it  also  gives  off  some  cutaneous  and  ar- 
ticular nerves. 

The  deep  terminal  branch  of  the  external  plantar  passes  above,  i.  e.,  deeper  than  the 


THE    EXTERlPrAt   PLA>rTAR   NERVE.  81§ 

flexor  accessorius,  changes  its  direction,  so  as  to  describfe  an  arch,  having  its  concavity 
turned  inward  and  backward,  and  the  convexity  outward  and  forward,  enters,  together 
with  the  external  plantar  artery,  above  which  it  is  situated,  between  the  adductor  polli 
cis  and  the  interossei,  and  is  lost  in  the  former  muscle. 

Before  reaching  the  adductor  pollicis  it  gives  off  some  articular  filaments  to  the  meta 
tarsal  and  tarso-metatarsal  articulations,  and  also  a  filament  for  the  fourth  lumbricalis. 
Beyond  the  adductor  pollicis  the  nerve  gives  off  the  ^amcw^ /or  the  third  lumbricalis ;  this 
filament,  which  is  remarkable  for  the  length  of  its  course,  passes  horizontally  forward, 
opposite  to  the  third  interosseous  space,  and  passes  through  the  fibres  of  the  transversus 
pedis,  to  reach  its  destination ;  it  then  gives  off  the  filaments  for  the  transversus,  and 
those  for  the  interosseous  muscles  of  the  third,  second,  and  first  spaces. 

Summary  of  the  External  Plantar  Nerve. — The  external  plantar  nerve,  therefore,  sup 
plies  cutaneous  filaments  to  the  outer  side  of  the  sole  of  the  foot,  to  the  fifth  toe,  of  which 
it  forms  both  collateral  nerves,  and  to  the  fourth  toe,  of  which  it  forms  the  external  col- 
lateral nerve.  It  also  gives  off  muscular  nerves  to  the  flexor  accessorius,  the  flexor  bre- 
vis,  and  abductor  digiti  minimi,  to  the  adductor  pollicis,  and  transversus  pedis,  to  all  the 
interossei,  and  to  the  two  external  lumbricales.  Lastly,  it  furnishes  some  articular 
filaments. 

Summary  of  the  Nerves  of  the  Lower  Extremity. — The  lower  extremity  is  supplied  with 
nerves  from  the  lumbar  and  sacral  plexuses. 

The  Lumbar  Plexus. — The  lumbar  plexus  gives  almost  all  its  branches  to  the  lower 
extremity,  viz.,  the  external  and  internal  inguinal  nerves,  the  obturator  nerve,  and  the 
crural  nerve  ;  the  lumbo-sacral  cord  is  also  distributed  to  the  lower  extremity  through 
the  medium  of  the  sacral  plexus. 

The  external  and  internal  inguinal  nerves  are  the  principal  cutaneous  nerves  of  the 
anterior  and  external  regions  of  the  thigh ;  the  obturator  nerve  is  a  muscular  nerve  in- 
tended for  the  obturator  externus,  the  three  adductors,  and  the  gracilis.* 

The  crural  nerve  is  a  musculo-cutaneous  nerve  which  supplies  the  following  parts : 
its  cutaneous  portion  is  distributed  to  the  skin  upon  the  anterior  region  of  the  thigh, 
upon  the  internal  region  of  the  leg,  and  internal  dorsal  region  of  the  foot ;  its  muscular 
portion  supplies  all  the  muscles  of  the  anterior  region  of  the  thigh  ;t  it  also  gives  several 
articular  nerves  to  the  hip  and  knee  joints. 

The  Sacral  Plexus. — The  sacral  plexus  is  entirely  distributed  to  the  lower  extremity, 
excepting  the  internal  pudic  nerve  and  certain  rectal  and  vesico-prostatic  branches  in 
the  male,  and  rectal,  vaginal,  and  uterine  branches  in  the  female. 

The  obturator  internus,  the  pyriformis,  the  gemelli,  and  the  quadratus  femoris,  are 
each  provided  with  a  special  nerve  from  the  sacral  plexus  ;  the  glutaeus  medius  and  min- 
imus, and  the  tensor  vaginae  femoris,  are  especially  supplied  by  the  superior  gluteal 
nerve,  and  the  glutaeus  maximus  by  the  inferior  gluteal  or  lesser  sciatic  nerve.  The 
last-named  nerve  also  furnishes  the  cutaneous  nerves  of  the  posterior  region  of  the  thigh. 

The  great  sciatic  is  the  nerve  of  the  posterior  region  of  the  thigh,  and  of  the  entire 
leg  and  foot.  It  supplies  all  the  muscles  of  the  posterior  region  of  the  thigh  ;  thus,  its 
external  popliteal  or  peroneal  division  supplies  the  muscles  of  the  external  region  of  the 
leg  by  its  musculo-cutaneous  branch,  and  the  muscles  of  the  anterior  region  by  its  in- 
terosseous branch  ;  it  also  supplies  the  external  region  of  the  leg,  and  the  dorsal  region 
of  the  foot. 

Its  internal  popliteal  or  tibial  division  supplies  all  the  muscles  of  the  posterior  region 
of  the  l6g,  the  skin  upon  the  internal  and  external  calcaneal  regions,  and  that  upon  the 
external  dorsal  region  of  the  foot. 

Of  its  terminal  branches,  the  internal  plantar  nerve  is  distributed  to  the  muscles  of  the 
internal  plantar  region  of  the  foot,  to  the  flexor  .brevis  digitorum,  to  the  two  internal 
lumbricales,  and  to  the  skin  of  the  internal  plantar  region  ;  lastly,  it  gives  off  the  col- 
lateral branches  of  the  toes,  excepting  the  two  for  the  fifth  toe,  and  the  external  collat- 
eral branch  of  the  fourth. 

The  external  plantar  nerve  is  distributed  to  the  muscles  of  the  external  plantar  region, 
to  the  flexor  accessorius,  to  all  the  interossei,  to  the  two  external  lumbricales,  to  the 
adductor  pollicis  and  transversus  pedis,  and  to  the  skin  of  the  external  plantar  region  : 
it  also  gives  the  internal  and  external  collateral  nerves  of  the  fifth  toe,  and  the  external 
collateral  nerve  of  the  fourth. 

Comparison  of  the  Nerves  of  the  Upper  and  Lower  Extremities. 
The  lumbo-sacral  plexus,  which  supplies  the  whole  of  the  lower  extremity,  precisely 
corresponds  to  the  cervico-brachial,  which  supplies  the- upper  extremity.  The  lumbar 
corresponds  to  the  cervical,  and  the  sacral  to  the  brachial  plexus.  The  connexion,  or 
sort  of  fusion  of  the  cervical  with  the  brachial  plexus,  and  of  the  lumbar  with  the  sacral 
plexus,  explains  why  it  is  found,  on  comparing  the  nerves  of  the  upper  and  lower  extrem- 

*  [The  obturator  also  supplies  part  of  the  pectineus,  and  sometimes  gives  cutaneous  branches  to  the  thigh 
,»nd  leg,  and  an  articular  filament  to  the  knee  (see  note  II,  p.  800).] 
fAnd  also  a  few  filaments  to  the  iliaciu,  psoas,  and  pectineus.] 


816  NEUROLOGY. 

ity,  that  several  of  the  nerves  arising  from  the  brachial  plexus  are  represented  by  nerves 
from  the  sacral  plexus,  and  that  several  of  those  from  the  cervical  plexus  have  their 
representatives  in  nerves  derived  from  the  lumbar  plexus.  It  will  be  seen,  moreover, 
that  this  analogy  ought  not  to  be  carried  too  far,  and  that  it  is  necessary,  in  making  the 
comparison,  to  exclude  all  nerves  which  belong  to  peculiar  organs  in  both  regions. 
Thus,  the  phrenic,  occipital,  and  auricular  nerves,  branches  of  the  cervical  plexus,  have 
no  representatives  in  the  lower  extremity,  nor  is  there  any  nerve  in  the  upper  extremity 
corresponding  to  the  internal  pudic. 

On  the  other  hand,  there  is  no  objection  to  admitting  that  the  external  and  internal 
inguinal  nerves  in  the  lower  extremity  are  represented  by  the  clavicular  nerves  in  the 
upper  extremity. 

The  crural  nerve,  a  branch  of  the  lumbar  plexus,  has  no  corresponding  branch  in  those 
of  the  cervical  plexus,  but  its  muscular  branches  are  represented  by  the  brachial  portion 
of  the  musculo-spiral  nerve,  and  its  cutaneous  branches  by  the  internal  brachial  cutane- 
ous. The  crural  nerve,  in  fact,  supplies  the  muscles  which  extend  the  leg  upon  the 
thigh,  in  the  same  way  that  the  musculo-spiral  nerve  supplies  the  muscles  which  ex- 
tend the  forearm  upon  the  arm ;  the  internal  saphenous  nerve  supplies  the  skin  of  the 
leg,  just  as  the  internal  brachial  cutaneous  is  distributed  to  the  skin  of  the  forearm. 

The  obturator  nerve,  which  supplies  the  adductors  of  the  thigh,  is  represented  by  the 
thoracic  nerves  and  the  nerve  for  the  latissimus  dorsi,  which  supply  the  pectoralis  ma» 
jor  and  latissimus  dorsi,  the  adductor  muscles  of  the  arm. 

The  gluteal  nerves  are  analogous  to  the  supra-scapular  and  circumflex  nerves.  The 
superior  gluteal,  which  is  distributed  to  the  glutaeus  medius  and  minimus,  corresponds 
to  the  supra-scapular,  which  belongs  to  the  supra-  and  infra-spinatus  ;  and  the  inferior 
gluteal  or  lesser  sciatic  nerve,  which  supplies  the  glutaeus  raaximus  and  the  skin  of  the 
thigh,  corresponds  to  the  circumflex  nerve,  which  is  distributed  to  the  deltoid,  and  the 
skin  of  the  arm. 

The  trunk  of  the  great  sciatic  nerve  represents  by  itself  the  musculo-cutaneous,  the 
ulnar,  and  the  median  nerves,  and  the  musculo-spiral  in  the  forearm. 

The  muscles  of  the  anterior  region  of  the  arm,  that  is  to  say,  the  muscles  that  flex  the 
forearm  upon  the  arm,  receive  their  branches  from  the  musculo-cutaneous  nerve,  just  as 
the  muscles  of  the  posterior  region  of  the  thigh,  or  the  flexors  of  the  leg  upon  the  thigh,, 
receive  theirs  from  the  great  sciatic. 

The  external  popliteal  nerve  represents  the  musculo-spiral  in  the  forearm  :  the  former, 
supplies  the  muscles  of  the  anterior  and  external  regions  of  the  leg,  while  the  latter  is 
distributed  to  the  muscles  of  the  posterior  and  external  regions  of  the  forearm  ;  the  for- 
mer gives  off  the  dorsal  cutaneous  nerves  of  the  foot,  and  the  latter  furnishes  the  dorsal 
cutaneous  nerves  of  the  hand. 

The  internal  popliteal  nerve  represents  the  median  and  ulnar  nerves  together.  The 
muscles  of  the  posterior  region  of  the  leg  are  supplied  by  the  internal  popliteal,  as  the 
muscles  of  the  anterior  region  of  the  forearm  are  supplied  by  the  median  and  the  ulnar. 

The  internal  popliteal  nerve  completes  the  series  of  dorsal  cutaneous  nerves  of  the> 
foot,  just  as  the  ulnar  nerve  completes  the  dorsal  nerves  of  the  hand. 

Lastly,  the  internal  plantar  nerve  gives  off  all  the  plantar  collateral  nerves  of  the  toes,; 
excepting  those  for  the  little  toe,  and  the  external  plantar  collateral  of  the  fourth  toe ; 
it  therefore  represents  the  palmar  portion  of  the  median  nerve ;  and  so  the  external  plan- 
tar represents  the  palmar  portion  of  the  ulnar  nerve,  and  completes  the  series  of  plantar 
collateral  nerves.  .; 


THE  CRANIAL  NERVES. 

Definition  and  Classifi/:ation. — The  Central  Extremities  of  the  Cranial  Nerves — viz.,  of. 
the  Olfactory — of  the  Optic — of  the  Common  Motor  Oculi — of  the  Pathetic — of  the  Tn-^ 
geminal — of  the  External  Motor  Oculi — of  the  Portio  Dura  and  Portio  Mollis  of  the  Sev- 
enth— of  the  Glosso-pharyngeal,  Pneumo-gastric,  and  Spinal  Accessory  Divisions  of  the 
Eighth — and  of  the  Ninth  Nerves. 

The  cranial  nerves  are  those  which  pass  through  the  foramina  in  the  base  of  the  cra- 
nium, not  those  which  arise  from  the  brain,  as  the  rather  generally  adopted  terms  cere- 
bral nerves  and  encephalic  nerves  would  seem  to  indicate. 

We  shall  follow  Willis  and  the  majority  of  anatomists  in  admitting  nine  pairs  of  cra- 
nial nerves,  which  are  almost  indifferently  named,  either  numerically,  from  the  order  of 
their  origin,  counting  from  before  backward,  or  they  are  named  from  their  distribution 
and  uses.    The  following  exhibits  their  nomenclature  upon  both  principles  : 
First  pair,  or  olfactory  nerves. 
Second  pair,  or  optic  nerves. 
Third  pair,  or  common  motor  nerves  of  the  eyes. 
Fourth  pair,  or  pathetic  nerves,  nervi  trochleares. 
Fifth  pair,  or  trifacial  nerves,  nervi  trigemini 


CENTRAL  EXTREMITY    OP   THE   OLFACTORY   NERVE.  817 

Sixth  pair,  or  external  motor  nerves  of  the  eyes,  nervi  abducentes. 

c.        »u      •    J    -J  J  •  *    (  portio  mollis,  or  auditory  nerve, 
Seventh  pair,  divided  mto  {  ^^-^  ^^^^^  ^^  f^^i^,  ^^^^ 

I  pneumogastric  nerve,  or  par  vagum. 

Eighth  pair,  divided  into  <  glosso-pharyngeal  nerve, 

(  spinal  accessory  nerve  of  Willis. 

Ninth  pair,  or  hypoglossal  nerve. 

Scemmering  has  introduced  the  following  modification  of  this  nomenclature.  He  has 
divided  the  seventh  pair  into  two,  viz.,  the  facial  nerves,  which  form  his  seventh  pair, 
and  the  auditory  nerves,  which  he  calls  the  eighth ;  and  then  he  has  divided  the  eighth 
pair  into  three  others,  namely,  a  ninth  pair  formed  by  the  glosso-pharyngeal  nerves,  a 
tenth  formed  by  the  pneumogastric  nerves,  an  eleventh  by  the  spinal  accessory  nerves ; 
the  hypoglossal  nerves,  therefore,  constitute  his  twelfth  pair. 

This  modification  is  founded  on  the  separation  of  nerves  so  completely  distinct  as  the 
fiicial  and  the  auditory,  which  have  only  been  described  together  because  they  enter  the 
same  canal  in  the  base  of  the  cranium,  namely,  the  internal  auditory  meatus. 

Still,  this  modification  is  a  useless  one,  and  it  has  the  greater  inconvenience  of  render- 
ing the  language  employed  obscure,  from  giving  a  double  acceptation  to  the  same  terms. 

It  would  be  more  philosophical  to  name  and  describe  the  cranial  nerves  from  behind 
forward,  so  that  the  hypoglossal  nerves  would  constitute  the  first  pair,  and  the  olfactory 
the  last. 

The  indisputable  analogy  which  exists  between  the  posterior  cranial  and  the  spinal 
nerves,  and,  moreover,  the  example  of  J.  F.  Meckel,  would  fully  warrant  this  innovation 
Nevertheless,  I  think  it  right  to  retain  the  old  usage,  and  to  proceed  from  before  back- 
ward, in  the  enumeration  as  well  as  in  the  description  of  the  nerves. 

As  the  origins  or  central  extremities  of  all  the  cranial  nerves  and  their  course  within 
the  cranium  can  be  studied  upon  the  same  brain,  I  have  thought  it  right  to  describe,  in 
one  article,  all  these  origins  or  central  extremities,  which  will  mutually  illustrate  each 
other  by  their  differences  and  their  anadogies  ;  the  experience  of  the  dissecting-room 
proves,  moreover,  that,  from  want  of  a  sufficient  number  of  brains  to  study  the  origin  of 
each  nerve  in  particular,  this  part  of  anatomy  is  generally  neglected. 

The  Central  Extremities  of  the  Cranial  Nerves. 

Dissection. — Two  preparations  are  required,  namely,  a  brain  removed  from  the  crani- 
um, together  with  the  origins  of  the  nerves  perfectly  preserved  ;  and  the  base  of  a  crani- 
um, together  with  those  parts  of  the  brain  which  are  near  the  origin  of  the  nerves.  The 
first  will  serve  for  the  examination  of  the  central  extremities  of  the  nerves  ;  and  the  sec- 
ond for  tracing  their  course  within  the  cranium. 

While  the  origin  of  all  the  spinal  nerves  is  uniform  and  regular,  that  of  the  cranial 
nerves  appears  to  be  subject  to  no  rule  ;  so  that  the  cranial  nerves  diflfer  as  much  from 
each  other  in  regard  to  their  origin  as  they  differ  collectively  from  the  spinal  nerves  in 
the  same  particular.  We  shall  see  presently,  however,  that  the  origins  of  all  but  the 
special  nerves  of  the  head  may,  to  a  certain  extent,  be  referred  to  the  same  law  of  double 
roots  (one  of  which  is  ganglionic)  which  presides  over  the  origin  of  the  spinal  nerves. 

The  Central  Extremity  of  the  Olfactory  JVerve. 

The  olfactory  nerves,  or  the  first  pair  of  cranial  nerves  (nerfs  ethmoidaux,  Chauss.,  1, 
fig.  276)  are  two  bands,  composed  of  white  and  gray  substance,  which  arise  from  the 
hindermost  convolution  of  the  anterior  lobe  of  the  brain,  run  forward  in  the  anfractuosity 
already  described  as  the  anfractuosity  of  the  olfactory  nerves,  and  expand  in  the  ethmoidal 
groove  into  a  sort  of  ganglion  or  bulb,  from  which  filaments  are  given  off  to  be  distribu- 
ted to  the  pituitary  membrane. 

In  regard  to  their  central  extremity  and  their  course  within  the  cavity  of  the  cranium, 
the  olfactory  nerves  are  singular,  and  their  peculiarities  justify  the  uncertainty  which 
has  for  a  long  time  prevailed,  and  still  prevails,  concerning  their  true  character.  The 
old  anatomists  did  not  regard  them  as  nerves,  but  as  prolongations  of  the  brain,  named 
by  them  caruncula:  or  processus  maxillares,  and  believed  to  be  intended  to  drain  off  the 
mucosity  of  that  organ  :  it  was  Massa,  according  to  Sprengel,  and  Zerbi,  according  to 
Haller,  who  first  connected  them  with  the  other  cranial  nerves  as  the  first  pair.  Com- 
parative anatomy,  which  probably  suggested  to  the  older  anatomists  the  opinion  which, 
they  held  concerning  these  nerves,  has  now  caused  some  doubts  as  to  the  propriety  of 
considering  them  as  nerves,  and  has  given  rise  to  the  opinion  that  they  are  the  repre- 
sentatives of  the  olfactory  lobes  of  the  lower  animals.*  Without  entering  here  into  dis? 
cussions  which  belong  to  philosophical  anatomy,  let  us  examine  the  most  remarkable- 
circumstances  connected  with  the  origin  and  cranial  course  of  this  nerve. 

Apparent  Origin. — The  olfactory  nerves  arise  from  the  cerebrum,  and  this  is  a  char- 

*  When  speaking  of  the  comparative  anatomy  of  the  brain,  it  was  mentioned  that  in  a  great  number  of  anK 
mals  there  existed,  in  front  of  the  cerebral  lobes  or  hemispheres,  a  pair  of  lobes  (olfactory  lobes),  which  were- 
^.ontinuous  with  the  nerves  distributed  to  the  pituitary  membrane,  and  the  development  of  which  oorresponde<li 
to  the  size  of  those  nerves,  and  to  the  relative  state  of  perfection  of  the  sense  of  smell. 

5L 


i^m 


NEUROLOGY. 


acter  which  belongs  exclusively  to  them ;  they  are  the  only  cerebral  nerves,  properly  so 
called. 

They  arise  from  the  hindermost  convolution  of  the  anterior  lobe,  in  front  of  the  ante- 
rior locus  perforatus  {h,fig.  276),  which  is  situated  behind  that  convolution.  This  origin 
consists  of  a  mammilla  or  pyramidal  enlargement,  gray  pyramid,  which  is  regarded  as  the 
gray  root  of  the  nerve.  This  grayish  enlargement,  which  can  be  very  well  seen  by  re- 
flecting the  nerve  backward,  is  prolonged  as  a  linear  tract  of  gray  substance  upon  the 
upper  surface  of  the  nerve. 

Besides  this  gray  enlargement  or  origin,  which  was  so  well  described  by  Scarpa,  there 
are  two  or  three  white  roots,  or,  rather,  certain  white  striae,  very  accurately  represent- 
ed by  Vicq  d'Azyr  ;  these  are  the  external-  or  long  root,  which  is  concealed  in  the  fissure 
of  Sylvius,  and  appears  to  me  to  arise  from  the  posterior  lobe  [middle  lobe]  of  the  cere- 
brum, or,  more  exactly,  from  the  posterior  lip  of  the  fissure  of  Sylvius  ;  and  the  internal 
or  short  root,  which  arises  from  the  innermost  convolution  of  the  anterior  lobe  and  joins 
the  long  root  at  an  acute  angle  ;  between  these  roots  we  often  see  one,  two,  or  even 
three  striae,  which  come  from  the  back  part  of  the  anterior  lobe.  It  would  be  both  use- 
less and  tedious  to  describe  all  the  varieties  of  this  origin. 

Real  Origin. — Anatomists  have  not  confined  themselves  to  the  investigation  of  the 
apparent  origin  of  the  olfactory  nerves,  but  have  also  endeavoured  to  ascertain  their 
deep  or  real  origin.  Willis  described  them  as  arising  from  the  medulla  oblongata,  Rid- 
ley from  the  corpus  callosum,  Vieussens,  Winslow,  and  Monro  from  the  corpora  striata.* 

If,  after  the  example  of  Scarpa,  a  transverse  perpendicular  section  of  the  brain  be 
made  opposite  the  junction  of  the  gray  and  white  roots  of  the  olfactory  nerves,  or  if  a 
stream  of  water  be  directed  upon  the  pyramidal  mammilla  above  described,  or,  lastly,  if 
Herbert  Mayo's  method  be  adopted,  and  the  origin  of  this  nerve  be  examined  in  a  brain 
hardened  in  alcohol,  it  will  be  seen  that,  besides  the  white  superficial  striae,  there  are  a 
great  number  of  deep  and  diverging  white  roots,  which  appear  to  me  to  come  from  the 
anterior  commissure,  and  not  from  the  corpus  striatum.! 

It  would  follow,  therefore,  that  the  olfactory  nerves  arise  by  a  commissure  like  the 
optic  nerves. 

Cranial  Course. — Having  arisen  in  this  manner  by  a  sort  of  bulb  or  gray  enlargement 
{enlargement  or  bulb  of  origin),  the  olfactory  nerve  immediately  tapers,  and  is  received 
into  the  antero-posterior  sulcus  intended  for  it,  which  conducts  it  as  far  as  the  ethmoidal 
groove  or  fossa  {I,  fig.  296),  where  it  forms  an  enlargement  or  bulb,  named  the  ethmoidal 
bulb,  which  is  analogous  in  many  respects  to  its  bulb  of  origin. 

When  seen  from  below,  the  olfactory  nerve  has  the  appearance  of  a  soft,  smooth  band, 
grooved  longitudinally  along  the  middle. t 

But,  on  reflecting  the  nerve  backward,  it  is  found  to  be  prismatic  and  triangular,  that 
its  two  lateral  surfaces  are  concave  and  correspond  to  the  convolutions  which  bound  the 
antero-posterior  sulcus  for  the  nerve,  and  that  its  upper  ridge  is  formed  by  a  Unear  tract 
of  gray  matter  which  connects  the  gray  substance  of  its  bulb  of  origin  with  that  of  the 
ethmoidal  bulb. 

The  arachnoid  has  a  peculiar  arrangement  in  relation  to  this  nerve  :  instead  of  im- 
mediately forming  a  sheath  for  it,  the  arachnoid  passes  below  it,  and  maintains  it  in 
contact  with  its  protecting  sulcus ;  while  the  pia  mater  passes  above  it,  and  lines  the 
sulcus.  The  nerve  is  not  entirely  separated  from  the  brain  until  about  a  few  lines  from 
the  ethmoidal  bulb. 

In  the  human  subject  the  olfactory  nerve  is  not  hollow  in  its  centre,  as  in  the  mam- 
malia ;  when  hardened  by  alcohol,  it  may  be  decomposed  into  white  parallel  fibres,  ex- 
actly similar  to  the  fibres  of  the  white  substance  of  the  brain. 

The  Ethmoidal  Bulb  or  Enlargements. — The  olfactory  nerves,  converging  towards  each 
other,  reach  the  ethmoidal  fossae,  where  each  immediately  expands  into  an  olive-shaped, 
ash-coloured,  and  extremely  soft  bulb  (the  ethmoidal  bulb,  I,  fig-  276),  to  which  Mala- 
carne  first  applied  the  term  ganglion,  and  which  is  formed  in  the  following  manner : 
The  white  filaments  of  which  the  olfactory  band  or  prism  is  composed  spread  out  like  a 
palm  branch  as  they  are  about  to  enter  the  bulb,  and  dip  into  the  gray  or  ash-coloured 
substance,  which  occupies  the  intervals  between  them  :  this  substance  is  precisely  anal- 
ogous to  the  gray  matter  of  the  brain,  but  is  less  consistent ;  it  also  resembles  the  sub- 
stance of  the  nervous  ganglia,  so  that  Scarpa  does  not  hesitate  to  regard  the  ethmoid 
bulb  as  a  ganglion.  From  this  enlargement  are  given  off"  the  olfactory  nerves  properly 
so  called,  which  seem  as  if  they  were  pressed  through  the  foramina  of  the  cribriform 

*  Chaussier,  ■who  adopted  the  latter  opinion,  called  the  corpora  striata  the  olfactory  lobes,  in  contradistinc- 
tion to  the  optic  thalami,  which  he  terms  the  optic  lobes.  But  comjiarative  anatomy  shows  that  there  is  nc 
relation  in  point  of  development  between  the  corpora  striata  and  the  olfactory  nerves. 

t  Scarpa  says  th«t  the  deep  roots  come  from  a  white  cord  placed  in  front  and  below  the  corpora  striata. 
Herbert  Mayo,  in  his  beautiful  plates,  has  represented  these  roots  as  coming  from  the  corpora  striata. 

%  Willis  ami  Santorini  have  noticed  this  groove.     Scarpa  has  observed  three  grooves,  which  he  regards  as 

con-esponding  to  as  many  lines  of  gray  substance.     M.  Hippolyte  Cloquet  {Anat.  Descript.,  t.  ii.,  p.  88)  goes 

still  farther  than  Scarpa,  and  describes  seven  longitudinal  strise,  three  of  which  are  gray,  and  four  white. 

Scarpa  has  very  justly  remarked,  that  the  proportion  of  ash-coloured  or  gray  substance  is  much  more  consid- 

"^ble  in  the  ftetus,  that  it  diminishes  in  the  adult,  and  that  it  scarcely,  if  at  all,  exists  in  the  old  smbject 


CENTRAL  EXTREMITY  OP  THE  OPTIC  NERVE.  819 

plate  of  the  ethmoid  bone.     It  is  said  that  the  gray  matter  sends  prolongations  through 
these  foramina,  bul  this  has  not  been  demonstrated. 

The  Central  Extremity  of  the  Optic  J^erve. 

The  optic  nerves,  or  second  pair  (2,  Jig.  276),  present  certain  peculiarities  in  their  tex- 
ture, and  in  their  cranial  course,  which  distinguish  them  from  all  other  nerves. 

They  have  this  peculiar  character,  that  they  arise  by  a  commissure  (the  optic  com- 
missure), or,  rather,  the  two  optic  nerves  unite  before  they  pass  to  their  respective  des- 
tinations. 

On  turning  the  cerebellum  forward,  it  is  seen  that  the  optic  tracts  (2,  fig.  295)  are 
continuous  with  the  corpora  geniculata  externa  (i),  and,  consequently,  take  their  origin 
from  the  optic  thalami  (a),  of  which  these  bodies  are  a  dependance.  In  some  cases, 
the  white  riband-like  band,  or  optic  tract,  which  constitutes  the  origin  of  the  optic  nerve, 
is  also  continuous  with  the  corpus  geniculatum  internum  (c).  In  the  human  subject,  the 
optic  nerves  never  arise,  either  entirely  or  in  part,  from  the  anterior  tubercula  quadri- 
gemina  (nates) ;  it  is  only  by  induction  that  this  mode  of  origin  has  been  admitted  in  the 
human  subject.* 

The  optic  tract  (2,  fig.  272),  having  arisen  from  the  corpus  geniculatum  externum 
(above  i),  with  which  it  is  continuous,  without  any  other  line  of  demarcation  excepting 
the  difference  of  colour,  assumes  the  appearance  of  a  thin  and  broad  riband,  which  turns 
round  the  cerebral  peduncle  (v),  parallel  to  and  on  the  inner  side  of  the  great  transverse 
fissure  of  the  brain.  During  this  course,  it  lies  in  contact  with  the  peduncle  of  the  cere- 
brum, from  which  it  may  be  separated  without  laceration,  excepting  at  its  outer  border, 
by  which  it  adheres  so  intimately  that  the  peduncle  has  been  supposed  to  supply  it  with 
several  roots. 

As  soon  as  it  gets  beyond  the  peduncle,  the  optic  tract  (»,  fig.  276)  is  condensed  into 
a  flat  cord,  which  leaves  the  peduncle,  passes  inward  and  forward,  and  unites  with  its 
fellow  of  the  opposite  side  to  form  the  chiasma  (square  space  of  Zinn,  t),  or,  rather,  to 
form,  with  the  optic  tract  of  the  opposite  side,  a  commissure  which  is  convex  in  front 
and  concave  behind. 

On  leaving  the  commissure,  it  completely  changes  its  direction  (2),  passing  forward 
and  outward,  to  enter  almost  immediately  into  the  optic  foramen  (2,  fig.  296). 

During  its  course  in  front  of  the  peduncle  of  the  cerebrum,  it  is  in  relation  with  the 
following  parts  :  behind,  with  the  tuber  cinereum  (v),  from  the  interior  of  which  some 
white  fibres  arise,  and  pass  to  the  chiasma  ;  in  front,  with  the  membrane  which  forms 
the  anterior  portion  of  the  floor  of  the  third  ventricle,  and  which  is  prolonged  upon  the 
upper  surface  of  the  chiasma.  ^ 

An  important  question  here  presents  itself,  viz..  Is  there  a  cOTlplete  or  partial  decus- 
sation of  the  optic  nerves  in  the  commissure  1  Do  these  two  nerves  irterlace  without 
decussating,  or,  rather,  is  there  an  intimate  mixture  of  their  fibres  1  Are  the  nerves 
placed  in  simple  juxtaposition  and  united  by  a  transverse  band  1  Lastly,  does  the  chi- 
asma constitute  a  commissure  in  wliich  the  two  optic  tracts  terminate,  or,  rather,  which 
serves  as  a  point  of  origin  for  the  optic  nerves  T  All  these  opinions  have  found  sup- 
porters, and  facts  have  been  quoted  in  favour  of  each  ;  a  circumstance  which  proves, 
not  that  there  are  anatomical  varieties  in  the  structure  of  the  chiasma,  but  that  its  struc- 
ture is  of  a  complex  nature. 

Comparative  anatomy  proves  that  the  optic  nerves  decussate  in  the  commissure  :  in 
fishes,  the  two  nerves  cross  without  uniting  :  it  is  also  proved  by  pathological  facts  ;  in 
a  great  number  of  cases  of  atrophy  of  one  eye,  atrophy  of  the  nerve  extended,  beyond 
the  commissure,  to  the  opposite  optic  tract. 

On  the  other  hand,  in  an  equally  large  number  of  cases  of  atrophy  of  one  eye,  the  dis- 
ease affected  the  optic  tract  of  the  same  side,  so  that  this  would  seem  to  show  that  there 
was  no  decussation. 

Lastly,  in  all  cases  of  atrophy  ctf  one  eye,  the  disease  affects  one  of  the  optic  nerves 
in  particular,  but  the  other  has  always  appeared  to  me  to  be  evidently  reduced  in  size. 

On  attempting  to  determine  the  point,  either  by  the  dissection  of  optic  nerves  harden- 
ed in  alcohol,  or  unravelled  by  means  of  a  stream  of  water,  it  is  seen  that  these  nerves 
present  the  following  threefold  arrangement  at  the  commissure  :  The  external  fibres  of 

*  The  origin  of  the  optic  nerves  varies  in  the  different  classes  of  animals.  In  birds,  in  which  these  nerves 
are  at  their  maximum  development,  they  arise  entirely  from  the  tubercula  quadrigeraina,  which  are  the  optic 
lobes  in  these  animals,  and  are  transposed  from  the  side  to  the  base  of  the  brain.  The  optic  thalami  do  not 
assist  in  forming  these  nerves.  In  rodentia,  a  small  number  of  fibres  from  the  optic  thalami  join  the  mass  of 
those  which  are  derived  from  the  nates.  In  canUTora,  the  number  of  filaments  from  the  tubercula  quadri- 
gemina  and  from  the  optic  thalami  are  almost  equal.  Moreover,  if  it  be  remembered  that  the  tubercula  quad- 
rigemina,  the  corpora  geniculata  externa  ai^  i|lt0ma,  and  the  optic  thalami  th^iulves,  belong  to  the  same 
system  of  organs,  and  form  a  continuation  of  th^'te-enforcing  fasciculi  (faisceimtSl^mnis)  of  the  medulla  ob- 
longata ;  and  if  other  facts  confirmatory  of  the  preceding  also  be  taken  into  conside^n^n,  namely,  that  a  white 
band  proceeds  on  each  side  from  the  natis  to  the  corpus  geniculatum  exter""-  -"■'<  tnother  from  the  testis  to 
the  corpus  geniculatum  internum,  it  wiU  be  easy  to  account  for  these  vu  n.  which  can  all  be  re- 

duced to  the  same  type.     It  is  of  some  importance  in  regard  to  this  quf  '  great  number  of  ciases 

of  atrophy  of  the  optic  nerve,  which  I  have  had  occasion  to  examine  in  t! -     jeo'i  tl"-  coipus  t'cnicu- 

'itum  was  affected,  and  not  the  natig. 


dl 


820  NEUROLOGY. 

the  commissure  do  not  decussate  ;  the  internal  fibres  (and  these  are  the  most  numerous; 
do  decussate  ;  and  the  posterior  fibres  are  continued  from  one  side  to  the  other  like  a 
commissure. 

Structure. — The  optic  nerve  has  a  peculiar  structure.  It  does  not  commence  by  fila- 
ments of  origin  or  distinct  cords,  like  the  other  nerves,  but  the  optic  tracts  and  the  optic 
commissure  are  composed  of  two  medullary  bands,  the  fibres  of  which  are  parallel  and 
in  immediate  contact  with  each  other,  precisely  as  in  the  olfactory  nerves,  and  in  the 
cerebral  substance  ;*  after  leaving  the  commissure,  the  optic  nerves  are  enveloped  in  a 
neurilemmatic  sheath,  from  the  internal  surface  of  which  certain  prolongations  or  septa 
are  given  off,  which  divide  the  interior  of  the  nerve  into  longitudinal  canals,  in  which  the 
medullary  substance  is  contained. 

I'he  optic  nerve,  therefore,  does  not  consist,  like  other  nerves,  of  a  plexiform  group 
of  nervous  filaments  or  cords,  but  of  a  collection  of  canals  dosely  applied  to  each  other, 
so  that  it  has  the  appearance  of  the  pith  of  the  rush  ;  hence,  doubtless,  the  opinion  of 
Eustachius  and  some  other  authors  who  conceived  that  the  optic  nerve  was  traversed 
by  canals  ;  and  hence,  also,  the  error  of  Reil,  who,  having  taken  the  structure  of  the  op- 
tic nerve  as  the  type  of  that  of  all  nerves,  regarded  each  nervous  cord  as  containing  a 
central  canal,  t 

The  Central  Extremity  of  the  Common  Motor  JVerve  of  the  Eye. 

The  apparent  origin  of  the  motor  nerves  of  the  eyes  (3,  fig.  276),  motores  oculorum,  com- 
mon oculo-muscular  nerve,  or  third  pair,  have  a  penicillate  character ;  these  origins  con- 
sist of  a  linear  series  of  very  delicate  filaments  proceeding  from  the  fasciculi  found  be 
tween  the  peduncles  of  the  cerebrum,  in  the  depression  between  the  pons  Varolii  and 
the  corpora  albicantia.     Some  filaments  converge  from  the  cerebral  peduncles  them- 
selves.t    This  origin  extends  about  a  line  and  a  half,  in  a  direction  obliquely  inward 
and  forward.     The  internal  filaments  of  origin  reach  the  middle  line,  so  that  Varolius 
and  Vieussens  believed  that  the  nerves  of  the  right  and  left  sides  are  continuous,  and 
xplained  the  simultaneous  action  of  the  two  eyes  by  this  anatomical  arrangement. 
Real  Origin. — In  a  brain  hardened  by  alcohol,  or,  still  better,  in  the  brain  of  a  foetus, 
Fig.  295.  the  filaments  of  origin  of  the  nerve  (3,  fig.  295)  can  be  easily 

traced  into  the  substance  of  the  median  fasciculi  (d)  found  between 
the  peduncles  of  the  cerebrum,  and  which  have  already  been  shown 
to  be  prolongations  of  the  fasciculi  of  re-enforcement  {fai-sceaux 
innomines)  of  the  medulla  oblongata.  The  filaments  of  the  nerves 
traverse  these  fasciculi  in  a  diverging  manner,  and  descend  to 
aJevel  with  the  pons,  beyond  which  I  have  not  been  able  to  trace 
<ftm,  on  account  of  their  slenderness  and  divergence.  I  have 
never  observed  any  of  them  running  towards  the  corpora  albican- 
tia, and  reaching  the  walls  of  the  third  ventricle  or  the  anterior 
commissure,  as  has  been  stated  by  some.  Nor  have  I  found  that 
they  are  re-enforced,  as  Gall  believed,  in  the  blackish  substance 
{locus  niger)  which  separates  the  peduncles  of  the  cerebrum,  prop- 
erly so  called,  from  the  prolongations  of  the  re-enforcing  fasciculi 
of  the  medulla  oblongata. 

Cranial  Course. — Having  arisen  in  this  manner,  the  fibres  of  the 
motor  oculi  nerve  converge  into  a  flat  bundle,  which  passes  be- 
tween the  posterior  cerebral  and  the  superior  cerebellar  arteries, 
upon  which  latter  it  is  reflected :  on  emerging  from  the  interval 
between  these  two  vessels  it  becomes  rounded,  and  then  passing 
upward,  outward,  and  forward,  enters  the  reticular  sub-arachnoid 
cellular  tissue  at  the  base  of  the  brain,  and  gains  the  side  of  the 
sella  turcica  (3,  fig.  296),  where  it  enters  a  proper  sheath  formed  for  it  by  the  dura  mater. 

The  Central  Extremity  of  the  Pathetic  Nerve. 

The  ncrvi  pathetici  (4,  fig.  276),  nerves  of  the  superior  oblique  muscle  of  the  eyes,  nervi 
trochleares,  the  internal  and  superior  oculo-muscular  nerves,  or  the  fourth  pair,  as  they  are 
variously  called,  are  the  smallest  of  the  cranial  nerves,  and  are  as  remarkable  for  being 

*  See  note,  p.  767. 

t  In  most  fishes,  whose  faculty  of  vision  is  exercised  in  a  less  transparent  medium  than  air,  the  optic  nerve 
IS  iformed  by  a  membrane  folded  upon  itself.  In  birds  of  prey,  the  membrane  is  sometimes  folded  like  a  fan, 
sometimes  like  the  leaves  of  a  book.  These  folds  are  intended  to  increase  the  extent  of  surface,  and  to  aug- 
ment the  power  of  vision.  Malpighi  first  made  this  observation  upon  the  optic  nerve  of  some  fishes.  Des- 
moulins,  who  has  studied  the  point  more  carefully,  has  shown  that  it  is  in  relation  with  the  perfection  of  the 
sense  of  sight.  The  same  thing  is  also  observed  in  the  retina:  thus,  in  the  eagle,  the  retina  presents  two, 
three,  or  four  superimposed  folds,  so  that  each  luminous  ray  acts  upon  sixteen  surfaces  instead  of  upon  two. 

t  In  fact,  the  exterml  fflaments  often  arise  from  the  inner  border,  and  even  from  the  lower  surface  of  the 
cerebral  peduncle,  at  a  certain  distance  from  the  inner  border  ;  in  this  case,  they  do  not  arise  from  the  pedun- 
f.les,  but  merely  pass  throQgh  them.  The  same  is  doubtless  the  case  with  the  filaments  of  origin  which  Rid- 
ley and  Molinelli  state  that  they  have  seen  coming  from  the  pons.  I  have  never  met  with  this  origin  from 
llie  pons,  nor  with  that  accessory  nerve  which  Malacarne  has  described  as  proceeding  from  the  upper  part  of 
'lie  jiedunclo  of  the  cerebellum,  turning  round  the  border  of  the  pons,  and  joining  the  motor  oculi  nerve. 


CENTRAL  EXTREMITY  OP  THE  TRIGEMINAL  NERVE.       821 

exclusively  distributed  to  the  superior  oblique  muscle  of  the  eyes,  as  for  their  origin  and 
for  the  length  of  their  course  within  the  cranium.  The  term  patheticus  is  derived  from 
the  opinion  that  the  superior  oblique  muscle  is  especially  concerned  in  the  expression  of 
love  and  of  compassion.     According  to  Bell,  this  nerve  is  the  respiratory  nerve  of  the  eye. 

The  apparent  origin  of  this  {i,fig.  280)  nerve  is  below  the  tubercula  quadrigemina,  on 
each  side  of  the  valve  of  Vieussens,  sometimes  by  one,  sometimes  by  two,  and  even  by 
three  or  four  roots.  Occasionally  there  are  several  roots  on  one  side,  and  only  a  single 
root  on  the  other.  The  nerves  of  the  two  sides  are  often  united  by  some  white  streaks, 
which  form  a  transverse  commissure  ;  at  other  times  they  do  not  arise  at  the  same  level. 

Real  Origin. — It  has  been  supposed  that  some  fibres  come  from  the  testes,  others  from 
the  cerebellum,  and  that  others  commence  much  lower  down  than  the  apparent  origin  ; 
all  that  can  be  seen  is,  that  these  nerves  {i,fig.  295)  arise  from  the  vdve  of  Vieussens, 
to  which  they  adhere  so  slightly  that  the  least  force  is  sufficient  to  detach  them. 

Cranial  Course. — Immediately  after  its  origin,  the  pathetic  nerve  turns  forward  and 
downward,  around  the  isthmus  of  the  encephalon,  in  front  of  the  anterior  border  of  the 
cerebellum,  and  thus  reaches  the  base  of  the  cranium  (4,  fig.  276),  accompanied  by  the 
superior  cerebellar  artery,  between  the  fifth  and  third  cranial  nerve,  but  much  nearer  to 
the  fifth  ;  it  then  passes  directly  forward  upon  the  side  of  the  sella  turcica  (4,  fig.  296), 
and  perforates  the  dura  mater,  considerably  below  the  third  nerve.  During  its  whole 
course,  it  is  situated  between  the  arachnoid  and  the  pia  mater,  in  the  reticular  cellular  tis- 
sue found  in  this  region. 

Wrisberg  says  that  the  right  pathetic  nerve  is  larger  than  the  left.  Ruysch  states 
that  he  found  this  nerve  double,  which  it  is  difficult  to  believe,  unless  he  meant  to  say 
that  it  bifurcated  at  its  origin.  Vesalius  regarded  this  nerve  as  a  root  of  the  third  cra- 
nial nerve ;  other  anatomists  have  considered  it  as  a  dependance  of  the  fifth. 

The  Central  Extremity  of  the  Trigeminal  J^erve. 

Apparent  Origin. — The  trigeminal  or  trifacial  nerves  (5,  fig.  276),  the  middle  sympathet- 
ic, or  the  fifth  pair,  are  the  largest  of  the  cranial  nerves,  excepting  the  optic  :  they  arise 
at  the  sides  of  the  pons  Varolii,  at  the  point  where  the  pons  becomes  continuous  with 
the  corresponding  peduncles  of  the  cerebellum,  and  exactly  where  the  middle  fibres  of 
the  pons  cross  in  front  of  the  inferior,  to  form  that  peduncle,  so  that  the  fasciculi  of  ori- 
gin appear  to  converge  from  a  narrow  slit  in  the  pons  itself.  This  origin  (^,fig.  295) 
consists  of  two  roots,  the  large  and  the  small  root,  which  have  a  small  prominence  be- 
tween them.  The  large  or  ganglionic  root  is  a  thick,  fasciculated  mass,  which  is,  as  it 
were,  constricted  at  its  point  of  emergence,  but  immediately  expands  into  a  thick,  flat 
bundle,  in  which  we  may  count  about  100  fibres.  On  tearing  off  this  bundle,  all  the  fibres 
do  not  give  way  opposite  the  same  place,  and  a  sort  of  mammillary  prominence  is  left, 
which  Bichat  regarded  as  belonging  to  the  pons,  as  intended  for  the  nerve  to  arise  from, 
and  as  having  the  effect  of  multiplying  the  surfaces  of  origin,  in  consequence  of  its  con- 
vexity. • 

The  small  root,  which  is  non-ganglionic,  is  composed  of  small  and  very  distinct  bun- 
dles, which  arise  from  the  pons,  above  and  behind  the  great  root,  by  several  cords ;  it 
emerges  from  the  pons  through  a  fissure  distinct  from  that  for  the  great  root,  and  gains 
the  upper  border  of  that  root. 

It  will  hereafter  be  seen  that  the  small  root  has  no  share  in  the  formation  of  the  gan- 
gliform  plexus  known  by  the  name  of  the  semilunar  or  Gasserian  ganglion,  and  that  it 
goes  exclusively  to  assist  in  forming  the  inferior  maxillary  division  of  the  fifth  nerve. 

Real  Origin. — Until  modem  times,  the  origin  of  the  fifth  nerve  had  not  been  traced  be- 
yond the  point  of  its  emergence.  Late  authors  have  described  its  real  origin  with  so 
much  detail  that  little  remains  to  be  desired.  Gall,  while  examining  the  fifth  nerve,  first 
in  mammalia  and  then  in  the  human  subject,  saw  that  in  many  the  origin  of  the  nerve  is 
concealed  by  certain  transverse  fibres  of  the  pons  which  do  not  exist  in  the  lower  ani- 
mals. Having  traced  the  nerve  by  clearing  off"  the  fibres  of  the  pons,  he  thought  he  ob- 
served that  the  great  root  divided  into  three  principal  fasciculi,  which  he  conceived  arose 
in  succession  from  the  gray  matter  of  the  pons,  and  which  he  succeeded  in  tracing  as  far 
as  to  the  outer  side  of  the  olivary  body.* 

Rolando,  by  successive  sections  made  through  the  pons  towards  the  medulla  oblongata, 
has  clearly  shown  that  the  great  root  of  the  fifth  nerve  consists  of  only  one  fasciculus, 
which  runs  downward  and  backward,  under  the  form  of  a  thick  cord  (see  fig.  295),  in  the 
substance  of  the  pons,  or,  rather,  at  the  boundary  between  the  pons  and  the  middle  ped- 
uncle of  the  cerebellum,  parallel  to  the  fasciculi  of  the  anterior  pyramid,  and  that  it  pro- 
gressively diminishes  in  size,  until  it  disappears  opposite  to  the  inferior  angle  of  the  fourth 
ventricle.  The  examination  of  this  origin  in  a  brain  hardened  by  alcohol,  or,  still  better, 
in  the  foetal  brain,  confirms  Rolando's  observations,  and  proves  that  the  great  root  of  the 

*  In  the  human  subject,  the  origin  of  the  fifth  nerve  is  extremely  deep-seated ;  it  is  not  so  deep  in  the  car- 
nivora,  and  still  more  superficial  in  ruminantia.  In  oviparous  animals,  which  have  neither  a  pons  Varolii,  nor 
lateral  lobes  of  the  cerebellum,  nor  pyramids,  nor  olivary  b  xiii  s,  the  origin  of  the  fifth  pair  is  seen  without 
any  dissection. 


«^ 


NEUROLOGY. 


^g-  296.  fifth  nerve  comes  from  the  back  part  of  the  mednHa  ob- 

longata,  from  the  interior  of  its  fasciculi  of  re-enforce- 
ment {faisceaux  innominis).*  As  to  the  small  root,  it 
cannot  be  traced  beyond  the  surface  of  the  pons.t 

Cranial  Course. — After  emerging  from  the  pons,  the 
fifth  nerve  passes  upward,  outward,  and  forward,  under 
the  form  of  a  flattened  bundle,  gains  the  upper  border 
of  the  petrous  portion  of  the  temporal  bone  {5,  Jig.  296), 
on  which  there  is. a  depression  that  is  converted  into  a 
canal  for  the  nerve  by  a  fold  of  the  dura  mater ;  the 
nerve  is  reflected  upon  this  border,  and  proceeds  as  will 
presently  be  described. 

The  Central  Extremity  of  the  External  Motor 
Jferve  of  the  Eye. 

The  external  motor  nerves  of  the  eye  (6,  fgs.  276,  295), 
external  oculo-muscular  nerves,  nervi  abducentes,  or  the  sixth  pair,  which  are  distributed 
exclusively  to  the  external  rectus  or  abductor  muscle  of  each  eye,  and  which  are  so  re- 
markable for  their  communications  with  the  sympathetic  system,  are  smaller  than  all 
the  cranial  nerves,  excepting  the  pathetic. 

Apparent  Origin. — The  statements  of  authors  regarding  the  apparent  Origin  of  this  nerve 
have  been  singularly  various  :  some,  with  Morgagni,  describe  it  as  arising  both  from  the 
pons  and  the  anterior  pyramids ;  others,  with  Vieussens,  from  the  pons  alone ;  and  others, 
with  Lieutaud,  from  the  anterior  pyramids  only.  Winslow  states  that  it  arises  between 
the  pons  Varolii  and  the  olivary  body,  and  Haller,  that  it  proceeds  from  the  furrow  be- 
tween the  anterior  p3rramid  and  the  pons. 

The  fact  is  that  this  nerve,  among  some  varieties  of  origin,  presents  two  very  distinct 
roots  (see  Jig.  276) :  one  internal  and  smaller,  which  arises  from  the  pons,  either  at  or 
near  its  lower  border ;  the  other  external  and  larger,  which  appears  to  emerge  on  the 
outer  side  of  the  upper  part  of  the  anterior  pyramid.  These  two  roots  are  fasciculated  : 
not  unfrequently  some  fibres  are  seen  arising  from  the  olivary  body,  or  from  the  furrow 
between  the  two  p)Tamids. 

Real  Origin. — This  is  more  easily  seen  in  mammalia  generally  than  in  man.  In  the 
former,  Gall  has  traced  it  along  the  side  of  the  pyramids.  Mayo  believes  that  the  fibres 
traverse  the  pons,  and  pass  to  the  back  part  of  the  medulla  oblongata.  From  the  tenu- 
ity and  whiteness  of  the  fibres  of  this  nerve,  I  have  not  been  able  to  trace  their  course 
in  the  substance  of  the  medulla. 

Cranial  Cmirse. — This  nerve  runs  upward  and  a  little  outward,  on  the  side  of  the  basi 
lar  groove,  and  perforates  the  dura  mater  (6,  Jig.  296)  opposite  to  and  above  the  apex  of 
the  petrous  portion  of  the  temporal  bone,  to  enter  the  cavernous  sinus  :  the  two  roots  of 
the  nerve  often  unite  before  perforating  the  dura  mater,  but  they  usually  pass  separately 
through  it  and  unite  within  the  sinus. 

The  Central  Extremity  of  the  Seventh  JVerve. 

The  central  extremity  of  the  facial  nerve,  or  portio  dura  of  the  seventh  nerve  (7,  Jig.  270, 
276).  The  facial  nerve  (on  the  inner  side  of  7)  arises  in  the  deep  depression  between 
the  middle  peduncle  of  the  cerebellum  and  the  pons  in  front  of  the  auditory  nerve  (on  the 
outer  side  of  7) :  it  emerges  from  the  front  of  the  restiform  body,  under  the  form  of  a 
fasciculated  band,  some  fibres  of  which  are  at  first  situated  at  a  distance  from  the  gen- 
eral mass,  but  soon  join  it ;  it  then  turns  round  the  lower  borders  of  the  peduncle  of  the 
cerebellum,  against  which  it  is  closely  applied,  and  then  becoming  free,  passes  outward 
and  upward.     It  has  no  neurilemma  up  to  the  point  where  it  becomes  free. 

The  real  origin  of  this  nerve  (7,  Jig.  295)  is  much  deeper  ;  it  may  be  traced  through 
the  restiform  body  into  the  fasciculus  of  re-enforcement,  near  the  median  furrow  of  the 
calamus  scriptorius. 

The  Central  Extremity  of  the  Auditory  Nerve. — The  auditory  nerve,  or  portio  mollis  of  the 
seventh  (on  the  outer  side  of  7,  fig.  275),  is  riband- shaped,  and  non-fasciculated  at  its  origin  : 
it  arises  (7',Jig.  295)  in  the  same  depression  as  the  facial  nerve,  but  behind  that  nerve,  and 
opposite  to  the  restiform  body :  it  presents  two  very  distinct  roots  :  an  anterior,  which 
is  arranged  like  the  facial  nerve ;  and  a  posterior,  which  turns  horizontally  round  the 
back  part  of  the  restiform  body,  appears  upon  the  posterior  surface  of  the  medulla  ob- 
longata (see  ^o-.  271),  and  separates  into  fibres,  which  may  be  traced  as  far  as  the  me- 

*  Vicq  d'Azyr  says  that  the  roots  of  this  nerve  extend  as  far  as  the  cerebellum,  but  this  assertion  has  not 
been  verified.  The  same  anatomist  declares  that  he  has  often  seen  the  fifth  nerve  of  the  right  side  larger  than 
that  of  the  left. 

t  According  to  Dr.  Alcock,  there  is  a  slight  enlargement  at  the  origin  of  the  large  root  of  the  fifth  nerve,  in 
the  lower  part  of  the  floor  of  the  fourth  vRntricle  ;  he  has  also  traced  the  small  root  to  this  enlargement,  from 
which  he  states  that  two  cords  descend,  one  to  the  anterior,  the  other  to  the  posterior  column  of  the  cord.— 
{Cyclop,  of  Anat.  and  Phys.,  art.  Fifth  Pair  of  Nf.rves.) 


CENTRAL   EXTREMITY   OF   THE    EIGHTH    NERVE.  823 

dian  furrow  of  the  calamus  scriptorius,  and  which  represent  some  of  the  barbs  of  the 
quill.  It  is  very  generally  admitted  that  the  auditory  nerves  have  a  tranverse  commis- 
sure, but  this  does  not  appear  to  me  to  be  clearly  demonstrated. 

The  portio  dura  and  the  portio  mollis  of  the  seventh  nerve,  which  arise  so  near  to  each 
other,  follow  the  same  cranial  course  :  they  arise  at  the  same  height  from  the  medulla 
oblongata,  pass  outward  and  upward  in  front  of  the  pneumogastric  or  sub-peduncular 
lobule  of  the  cerebellum,  and  enter  the  internal  auditory  meatus  {7,  fig.  296).  During 
this  course,  the  portio  dura  always  lies  in  front  of  the  portio  mollis. 

The  auditory  nerve  is  the  softest  of  all  the  cranial  nerves  ;  the  difference  between  it 
and  the  facial  nerve,  in  this  respect,  has  led,  in  a  great  measure,  to  the  subdivision  of 
the  nerves  into  the  soft  or  sensory,  and  the  hard  or  motor. 

The  Central  Extremity  of  the  Eighth  Jferve. 

Of  the  three  nerves  on  each  side  which  together  constitute  the  eighth  nerve  (8,  figs. 
370,  276,  295),  the  glosso-pharyngeal  is  the  highest,  the  pneumogastric  is  the  next,  and  the 
spinal  accessory  is  the  lowest. 

The  Central  Extremity  of  the  Glosso-pharyngeal  and  Pneumogastric  Nerves. — ^The  glosso- 
pharyngeal and  pneumogastric  nerves  have  a  common  origin.  They  arise,  like  the  spinal 
nerves,  by  a  hnear  series  of  funiculi  (see  fig.  270),  which  come  off,  not  from  the  furrows 
between  the  olivary  and  restiform  bodies,  but  from  the  restiform  body  itself,  on  a  hne 
with  the  auditory  nerves.  Soemmering  states  that  he  has  seen  some  of  these  funiculi 
arise  from  the  anterior  wall  of  the  fourth  ventricle. 

Moreover,  as  in  the  spinal  nerves,  each  funiculus  of  origin  is  formed  by  the  union  of 
two  or  three  converging  filaments  ;  the  funiculi  of  the  glosso-pharyngeal  nerve,  which 
are  the  highest,  and  which  come  off  immediately  below  the  auditory  nerve,  are  not  dis- 
tinct at  their  origin  from  those  of  the  pneumogastric ;  nor,  as  will  presently  be  stated, 
are  the  funiculi  of  origin  of  the  pneumogastric  distinct  from  those  of  the  spinal  acces- 
sory. The  division  into  the  three  nerves  cannot  be  made  until  after  the  funiculi  are 
finally  grouped. 

It  has  been  stated,  but  without  proof,  that  the  fibres  of  the  glosso-pharyngeal  and 
pneumogastric  nerves  might  be  traced  through  the  restiform  body  as  far  as  the  back  of 
the  medulla  oblongata.  The  funiculi  of  origin  of  these  nerves,  which  are  enveloped  by 
the  neurilemma  at  the  point  where  they  emerge  from  the  medulla,  are  so  small  that, 
when  torn  off,  scarcely  any  trace  of  their  points  of  attachment  can  be  detected  even  by 
the  aid  of  a  lens. 

The  Central  Extremity  of  the  Spinal  Accessory  Nerve  of  Willis. — The  origin  of  the  spiTial 
accessory  nerve  (.s,fig.  295)  is  quite  peculiar,  and  has  obtained  much  notice  from  modem 
anatomists. 

It  arises  from  the  sides  of  the  cervical  region  of  the  spinal  cord,  between  the  anterior 
and  posterior  roots  of  the  cervical  nerves,  and  behind  the  ligamentum  denticulatum. 
Sir  C.  Bell,  who  classes  it  among  the  respiratory  nerves,  strongly  insists  upon  its  ori- 
gin from  that  column  of  the  cord  which  is  situated  between  the  anterior  and  posterior 
columns,  in  a  line  with  the  pneumogastric  and  facial  nerves,  which  column  (the  respira- 
tory tract)  he  assumes  to  give  origin  solely  to  the  respiratory  nerves.  The  funiculi  of 
origin  of  the  spinal  accessory  vary  much  both  in  number  and  size,  and  are  widely  separ- 
a.ted  from  each  other :  the  lowest  as  well  as  the  highest  funiculi  appear  to  me  to  be  con- 
tinuous with  the  posterior  roots  of  the  spinal  nerves  ;  and,  again,  the  -liighest  are  con- 
tinuous above  with  those  of  the  pneumogastric  nerve,  and  appear  to  me  to  establish  a 
transition  between  the  origin  of  that  nerve  and  the  posterior  roots  of  the  spinal  nerves. 

The  lowest  funiculus  of  the  spinal  accessory  is  generally  situated  not  lower  than  the 
fifth  cervical  nerve  ;  it  has  been  seen  to  arise  opposite  the  sixth,  and  even  the  seventh 
cervical  nerve  ;  the  latter  is  the  normal  condition  in  the  ox. 

It  is  of  importance  to  remark  the  connexion  which  exists  between  the  spinal  acces- 
sory nerve  and  the  first  cervical  or  sub-occipital  nen^e.  Almost  always  one  or  two,  and 
frequently  all  of  the  posterior  funiculi  of  the  sub-occipital,  join  the  spinal  accessory.  Not 
unfrequently  a  small  funiculus  joins  the  spinal  accessory  from  the  second  cervical  nerve. 
Opposite  its  connexion  with  the  sub-occipital  nerve,  the  spinal  accessory  sometimes  pre- 
sents a  gangliform  enlargement,  which  was  well  described  by  Huber  (in  ganglion  vix 
hordeaceum  intumescit  ncrvus  accessorius).  In  some  cases  a  filament  proceeds  from  this 
ganglion  and  joins  the  anterior  roots  of  the  sub-occipital  nerve.  Winslow  believed  that 
the  funicuh  of  origin  of  the  spinal  accessory  communicated  with  the  hypoglo.ssal :  this  is 
an  error.  The  greater  number  and  even  the  whole  of  the  funiculi  of  the  sub-occipital 
nerve  have  been  seen  to  join  the  spinal  accessory,  in  which  case,  filaments  from  the  latter 
nerve  always  supply  the  place  of  those  which  are  usually  furnished  by  the  first  cervical.* 

The  Cranial  Course  of  the  Glosso-pharyngeal  and  Pneumogastric  Nerves. — They  pass 
horizontally  outward,  in  contact  with  the  lateral  fibrous  layer  of  the  fourth  ventricle, 
forming  two  groups  having  a  very  small  interval  between  them.  The  two,  three,  or 
four  small  bundles  which  constitute  the  glosso-pharyngeal  nerve  pass  through  a  special 

*  Lobstein,  De  Ntrvo  Spinali.    Vide  Scriptor.  Neurol.,  Minor  de  Ludwig.,  t.  ii. 


824  NEUROLOGY. 

opening  m  the  upper  part  of  the  foramen  lacerum  posterius  (8,  Jig.  296).  The  bundles 
which  form  the  pneumogastric  nerve  are  collected  together  and  pass  through  the  same 
foramen,  but  by  a  distinct  opening  from  the  preceding  one. 

The  cranial,  or,  rather,  the  vertebral  course  of  the  spinal  accessory  nerve  of  Willis,  is  re- 
markable. This  nerve,  which  is  very  small  below,  where  it  is  formed  by  one  or  two 
funiculi,  ascends  vertically  upon  the  side  of  the  cervical  region  of  the  spinal  cord,  to 
which  it  is  closely  applied  below,  just  behind  the  ligamentum  denticulatum,  and  from 
which  it  is  separated  above,  where  it  is  immediately  in  front  of  the  posterior  roots  of  the 
cervical  nerves  ;  it  goes  on  increasing  in  size  as  it  receives  additional  funiculi,  which  are 
blended  with  it ;  having  arrived  a  few  lines  below  the  posterior  lacerated  foramen,  it 
passes  upward  and  outward  to  enter  the  same  opening  as  the  pneumogastric,  being  situ- 
ated below  that  nerve,  and  emerging  with  it  from  the  cranium. 

The  Central  Extremity  of  the  Hypoglossal  Jferve. 

The  hypoglossal  nerves  {9,  figs.  276,  295),  or  ninth  pair,  arise  on  each  side,  from  the  fur- 
row between  the  olivary  and  pyramidal  bodies,  in  the  same  manner  as  the  spinal  nerves, 
i.  e.,  by  a  linear  series  of  funiculi  placed  one  above  the  other. 

The  furrow  from  which  the  funiculi  of  the  ninth  nerve  arise  is  continuous  with  the 
line  formed  by  the  origins  of  the  anterior  roots  of  the  spinal  nerves  ;  no  funiculus  arises 
from  the  line  formed  by  the  posterior  roots.*  The  relation  of  the  origin  of  the  ninth 
nerve  with  the  vertebral  artery  in  front,  and  the  vascular  ramifications  which  surround 
the  funiculi  of  this  origin,  require  to  be  mentioned. 

The  real  origin  of  the  ninth  nerve  cannot  be  traced  beyond  its  apparent  origin.  It  is 
certain  that  no  fibres  come  from  the  pyramids  ;  it  has  appeared  to  me  that  the  fibres  en- 
tered the  substance  of  the  olivary  bodies,  in  which  they  could  not  be  traced  to  any  depth. 

Cranial  Course. — All  the  funiculi  of  origin  of  the  hypoglossal  nerve  commence  by  two 
or  three  filaments,  which  are  immediately  covered  by  the  neurilemma ;  they  are  then 
grouped  into  two  or  three  bundles,  which  pass  horizontally  outward  to  the  anterior  con- 
dyloid foramen,  through  which  (9,  fig.  296)  they  almost  always  pass  separately.  Thus 
the  dura  mater  forms  two  and  sometimes  three  distinct  canals  for  the  hypoglossal  nerve. 


DISTRIBUTION  OF  THE  CRANIAL  NERVES. 

The  First  Pair  or  Olfactory  Nerves. — The  Second  or  Optic  Nerves. — The  Third  or  Common 
Motor  Nerves. — The  Fourth  or  Pathetic  Nerves. — The  Fifth  or  Trigeminal  Nerves — the 
Ophthalmic  Division  of  the  Fifth,  and  its  Lachrymal,  Frontal,  and  Nasal  Branches — the 
Ophthalmic  Ganglion — the  Superior  Maxillary  Division  of  the  Fifth,  and  its  Orbital  Branch 
— the  Spheno-palatine  Ganglion,  and  its  Palatine,  Spheno-palatine,  and  Vidian  Branches — 
the  Posterior  and  Anterior  Dental,  and  the  Terminal  Branches  of  the  Superior  Maxillary 
Nerve — the  Inferior  Maxillary  Division  of  the  Fifth — its  Collateral  Branches,  viz.,  the 
Deep  Temporal,  the  Masseteric,  Buccal,  and  Internal  Pterygoid,  and  Auriculo-temporal — 
its  Terminal  Branches,  viz.,  the  Lingual  and  Inferior  Dental — the  Otic  Ganglion. —  The 
Sixth  Pair  or  External  Motor  Nerves. — The  Seventh  Pair — the  Portio  Dura  or  the  Facial 
Nerve — its  Collateral  Branches — its  Terminal  Branches  viz.,  the  Temporo-facial  and 
Cervico-fascial — the  Portio  Mollis  or  Auditory  Nerve. — The  Eighth  Pair — its  First  Por- 
tion of  the  Glosso-pharyngeal  Nerve — its  Second  Portion  or  the  Pneumogastric  Nerve,  di- 
vided into  a  Cranial,  Cervical  Thoracic,  and  Abdominal  Part — its  Third  Portion,  or  the 
Spinal  Accessory  Nerve. — The  Ninth  Pair  or  the  Hypoglossal  Nerves. — General  View  of 
the  Cranial  Nerves. 

The  First  Pair,  or  the  Olfactory  Nervks. 

Dissection. — Harden  the  nerve  in  dilute  nitric  acid.  Examine  the  pituitary  membrane, 
not  from  its  free  surface,  but  from  the  surface  which  adheres  to  the  periosteum.  The 
nerve  ramifies  between  the  periosteum  and  the  pituitary  membrane. 

Before  the  time  of  Scarpa,  the  olfactory  pedicles  or  bands  and  the  ethmoidal  bulb  were 
the  only  parts  well  known ;  the  passage  of  the  olfactory  nerves  through  the  foramina  of 
the  cribriform  plate,  and  their  distribution  in  the  pituitary  membrane,  were  scarcely 
noticed. 

Passage  of  the  Olfactoy  Nerves  through  the  Cribriform  Plate. — I  must  here  remind  the 
student  that  the  cribriform  plate  of  the  ethmoid  bone  is  perforated  by  foramina,  or,  rather, 
by  different  sets  of  canals  which  ramify  in  its  substance  ;  that  some  of  these  canals  ter- 
minate directly  upon  the  roof  or  upper  wall  of  the  nasal  fossae,  and  that  the  others  are 
divided  into  an  internal  set,  which  pass  along  the  septum  and  end  by  becoming  grooves, 
and  an  external  set,  which  descend  on  the  superior  and  middle  turbinated  bones,  and  on 
the  rough  quadrilateral  surface  in  front  of  them. 

The  olfactory  nerves  arise  from  the  ethmoidal  bulb  {I,  figs.  296,  297)  by  a  considera- 

*  tin  the  ox  and  dog  Mayer  discovered  a  small  posterior  root  with  a  ganglion  for  this  nerve  ;  and  he  states 
that  he  once  found  a  small  posterior  root  on  one  side  in  the  human  subject.] 


THE  OPTIC   NERVES.  825 

Ftg  297.  ^^^  number  of  white  bundles,  which  immediately  pass  through  the 

"  cribriform  plate,  and  divide  and  ramify  {i.,jig.  297)  in  the  same 

way  as  the  bony  canals  themselves ;  the  dura  mater  forms  a 
sheath  for  each  of  the  subdivisions  of  the  nerve,  and  supports 
their  soft  substance.  All  these  nervous  filaments  are  distributed 
upon  the  septum  (cZ)  and  upon  all  the  external  wall  (a,  fig.  299)  of 
each  nasal  fossa  ;  the  anterior  run  forward,  the  middle  vertically 
downward,  and  the  posterior  backward.  Some  of  them  only  in- 
terlace as  they  leave  the  cribriform  plate.  They  all  expand  into 
very  delicate  pencils.  They  are  situated  between  the  periosteum 
and  the  pituitary  membrane,  and  none  of  them  reach  either  the 
inferior  turbinated  bone,  or  the  maxillary,  sphenoidal,  or  ethmoidal  sinuses  ;  on  the  inner 
wall  of  each  fossa  they  do  not  pass  lower  than  the  middle  of  the  septum ;  and  on  the 
outer  wall  they  do  not  descend  below  the  middle  turbinated  bone.* 

With  regard  to  the  ultimate  termination  of  the  fibres  of  the  olfactory  nerve,  there  has 
been  a  difference  of  opinion  ;  some  believe  that  they  terminate  in  papillae  like  those  of 
the  skin  ;  and  others  imagine  that  they  expand  into  a  membrane,  like  the  optic  nerve  in 
the  retina  and  the  auditory  nerve  in  the  membranous  labyrinth.  I  have  never  seen 
them  terminate  otherwise  than  by  pencils  of  extremely  delicate  filaments  very  closely 
apphed  to  each  other. 

Function. — The  olfactory  nerves  are  the  essential  organs  of  smell.  Their  distribution 
proves  that  the  sense  of  smell  resides  essentially  and  exclusively  in  the  roof  of  the  nasal 
fossae  and  the  immediately  adjacent  parts. 

The  Second  Pair,  or  the  Optic  Nerves. 

The  optic  nerves  have  already  been  described  from  their  origin  to  the  optic  commis- 
sure, and  from  the  commissure  to  the  optic  foramina  (2,  Jig.  296) ;  they  pass  through 
these  foramina  together  with  the  ophthalmic  arteries  which  are  below  them  ;  they  are 
also  accompanied  by  a  sheath  formed  by  the  dura  mater  and  by  a  prolongation  of  the 
arachnoid,  the  latter  being  immediately  reflected  from  them. 

The  optic  nerve,  which  is  flattened  up  to  this  point,  becomes  rounded  on  emerging 
from  the  optic  foramen,  and  is  received  in  a  fibrous  ring  formed  by  the  origins  of  the 
muscles  of  the  eye  ;  it  here,  also,  changes  its  direction  shghtly,  for,  instead  of  passing 
obliquely  forward  and  outward,  it  runs  almost  directly  forward  to  the  globe  of  the  eye, 
which  it  enters  behind,  and  somewhat  below,  and  to  the  inner  side  (see  o,  Jigs.  237,  238, 
240).  There  is  a  very  evident  circular  constriction  at  the  point  where  the  optic  nerve 
enters  the  eye.t 

During  its  course  in  the  orbit,  the  optic  nerve  is  surrounded  by  a  great  quantity  of 
adipose  tissue,  which  separates  it  from  the  muscles  and  nerves.  The  ophthalmic  gan- 
glion and  the  ciliary  nerves  and  vessels  are  in  immediate  contact  with  it.  It  is  accom- 
panied, as  far  as  the  sclerotic,  by  a  fibrous  sheath  given  off  from  the  dura  mater,  so  that 
this  nerve  differs  from  all  others,  in  being  provided  with  two  protecting  sheaths,  name- 
ly, a  proper  neurilemma,  and  a  sheath  formed  by  the  dura  mater.  A  section  of  the  optic 
nerve  also  presents  throughout  its  course  that  peculiar  appearance  resembling  the  pith 
of  the  rush,  which  we  have  already  described  as  commencing  at  the  commissure  (see 
Central  Extremity  of  the  Optic  Nerve). 

As  it  enters  the  ball  of  the  eye  the  nerve  loses  its  two  sheaths,  which  appear  to  be- 
come continuous  with  the  sclerotic,  and  is  thus  reduced  to  its  pulp,  which  spreads  out 
to  form  the  retina.  In  some  subjects  the  retina  presents  a  distinctly  radiated  appear- 
ance around  the  abrupt  termination  of  the  nerve  (see  Globe  of  the  Eye — Retina). 

Function. — The  optic  nerves  are  the  nerves  of  vision  ;  their  continuity  writh  the  retina 
leaves  no  doubt  of  this  being  their  function. 

The  Third  Pair,  or  the  Common  Motor  Nerves  of  the  Eyes. 

Dissection. — All  the  nerves  of  the  orbit  should  be  studied  together.  The  frontal  and 
lachrymal  branches  of  the  ophthalmic  nerve  and  the  fourth  nerve  may  be  first  examined ; 
then  the  orbital  portion  of  the  nasal  branch  of  the  ophthalmic,  which  will  afterward  be 
traced  into  the  nasal  fossae  ;  next,  the  common  and  external  motor  nerves  ;  and,  lastly, 
the  ophthalmic  ganglion  and  the  optic  nerve. 

The  common  motor  nerve  has  already  been  traced  {^,Jigs.  298,  301)  from  its  origin  with- 
in the  peduncles  of  the  cerebrum  to  the  side  of  the  quadrilateral  plate  of  the  sphenoid 
bone,  below  and  to  the  outer  side  of  the  posterior  clinoid  process  ;  in  this  situation  (3, 
Jig.  296)  it  is  received  into  a  groove  formed  for  it  by  the  dura  mater ;  it  then  perforates 
that  membrane,  enters  the  cavernous  sinus,  passes  through  it  from  behind  forward  and 

*  In  mammalia,  and  particularly  in  the  horse,  a  cord  arises  from  the  olfactory  nerve,  runs  downward  and 
forward  alon?  the  septum,  parallel  to  and  in  front  of  the  naso-palatine  nerve,  and  terminates  in  the  small  in- 
cisory  cavity  which  exists  in  the  arch  of  the  palate  in  the  lower  animals,  and  is  thought  by  M.  Jacobson  to  be 
the  seat  of  a  sixth  sense. 

t  M.Arnold,  in  his  beautiful  plates  of  the  nerves  of  the  head,  has  represented  two  very  delicate  filament* 
as  establishing  a  communicativ^n  between  the  suoorior  maxillary  and  the  optic  nerves. 

5M 


826  NEUROLOGY. 

a  little  outward,  and  before  entering  the  orbit  divides  into  two  branches  of  unequal  size, 
of  which  one  is  superior  and  the  other  inferior. 

The  following  are  its  relations  in  the  cavernous  sinus  :  it  is  situated  in  the  substance 
of  the  external  wall  of  the  sinus,  to  the  outer  side  of  the  internal  carotid  artery,  above 
the  external  motor  nerve,  and  to  the  inner  side  of  the  fourth  nerve  and  of  the  ophthalmic 
branch  of  the  fifth ;  it  enters  the  orbit  at  the  innermost,  and,  consequently,  the  widest 
part  of  the  sphenoidal  fissure. 

It  has  no  immediate  relations  with  the  other  nerves  that  pass  through  the  cavernous 
sinus,  until  it  is  about  to  enter  the  orbit ;  at  this  point  it  receives  some  very  delicate  fil- 
aments from  the  cavernous  plexus  of  the  sympathetic,  and  an  equally  small  filament 
from  the  ophthalmic  branch  of  the  fifth  nerve;  after  which,  the  external  motor  nerve* 
becomes  situated  below  the  common  motor,  while  the  frontal  and  pathetic  nerves  cross 
above  it ;  the  nasal  branch  of  the  ophthalmic  is  in  contact  with  its  outer  side,  and  then 
passes  between  its  two  divisions. 

As  the  common  motor  nerve  passes  through  the  sphenoidal  fissure,  the  tendon  of  the 
external  rectus  forms  a  fibrous  ring  around  it,  which  is  quite  distinct  from  the  ring  be- 
longing to  the  optic  nerve ;  this  fibrous  ring  also  surrounds  the  external  motor  nerve 
and  the  nasal  branch  of  the  ophthalmic. 

The  superior  terminal  division  of  the  third  nerve  is  much  smaller  than  the  inferior ;  it 
passes  below  the  superior  rectus  of  the  eye,  and  immediately  expands  into  a  great  num- 
ber of  filaments,  one  of  which  is  very  large,  and  runs  along  the  outer  border  of  that  mus- 
cle. Almost  all  these  filaments  are  intended  for  the  superior  rectus,  which  they  enter 
by  its  under  surface.  Several  of  them  are  very  small,  and  run  along  the  inner  border 
of  the  superior  rectus,  to  be  distributed  to  the  levator  palpebrse  superioris.  The  fila- 
ments for  this  last  muscle  are  proportionally  much  smaller  and  less  numerous  than  those 
for  the  superior  rectus. 

The  inferior  terminal  division  is  the  true  continuation  of  the  nerve  both  as  regards  its 
size  and  direction  ;  it  runs  between  the  optic  nerve  and  the  external  motor  nerve,  which 
is  in  contact  with  it,  and  which  lies  between  it  and  the  external  rectus  muscle,  and  al- 
most immediately  subdivides  into  three  branches :  an  internal,  which,  passing  beneath 
the  optic  nerve,  gains  the  internal  surface  of  the  internal  rectus,  and  ramifies  in  that 
muscle  ;  a  median,  which  penetrates  the  inferior  rectus  ;  and  an  external  branch,  which 
is  the  smallest,  and  runs  along  the  outer  side  of  the  inferior  rectus  as  far  as  the  inferior 
oblique,  and  enters  that  muscle  at  its  posterior  border,  and  almost  at  right  angles.  The 
short,  thick  filament  which  enters  the  ophthalmic  ganglion  proceeds  from  the  branch  for 
the  inferior  oblique  muscle.  This  filament  for  the  ganglion  sometimes  arises  separately, 
and  appears  to  be  a  fourth  branch  of  the  inferior  division  of  the  third  nerve. t 

Function. — The  common  motor  nerve  supplies  all  the  muscles  of  the  eye,  excepting 
the  superior  oblique  and  the  external  rectus.  It  is  remarkably  large,  and  is  proportion- 
ed to  the  activity  and  frequency  of  contraction  in  these  muscles.  That  the  muscular 
nerves  do  not  terminate  in  loops  or  arches  may  be  well  seen  in  these  muscles. 

The  Fourth  Pair,  or  the  Pathetic  Nerves. 

The  pathetic  nerve  {4:,  figs.  298,  301)  is  remarkable  for  its  extreme  slenderness,  for  its 
origin  upon  the  side  of  the  valve  of  Vieussens,  for  the  length  of  its  cranial  portion,  and 
for  its  winding  course  around  the  peduncle  of  the  cerebrum  ;  it  enters  (4,  Jig.  296)  an 
opening  in  the  dura  mater  upon  the  anterior  extremity  of  the  inner  or  concave  border  of 
the  tentorium  cerebelli,  on  the  outer  side  of  the  common  motor  nerve  ;  it  runs  in  the  sub- 
stance of  the  external  wall  of  the  cavernous  sinus,  to  the  outer  side  and  a  little  below 
the  level  of  the  common  motor  nerve  (3),  and  directly  above  the  ophthalmic  division  (a) 
of  the  fifth,  to  which  it  sends  otf  a  filament,  and  then,  running  along  the  upper  surface 
of  that  nerve,  communicates  with  it  by  several  twigs  ;  it  then  enters  the  orbit  together 
with  the  frontal  nerve,  the  principal  branch  of  the  ophthalmic,  through  the  widest  part 
of  the  sphenoidal  fissure,  passes  inward  and  forward,  leaves  the  frontal  nerve,  crosses 
obliquely  over  the  superior  branch  of  the  common  motor  nerve  and  the  back  part  of  the 
levator  palpebra;  superioris  and  superior  rectus  of  the  eye,  to  reach  the  superior  oblique, 
and,  having  previously  ramified,  enters  the  upper  border  of  that  muscle.  During  its  course 
in  the  orbit,  this  nerve,  like  the  frontal  branch  of  the  ophthalmic,  is  in  contact  with  the 
periosteum. 

The  union  of  the  ophthalmic  branch  and  the  pathetic  nerve  is  so  intimate  that  it  has 
been  imagined  that  the  lachrymal  nerve  is  always  derived  entirely  from  the  pathetic,  and 
not  from  the  ophthalmic  itself  But  a  careful  dissection  shows  that  this  is  generally  in- 
correct.   However,  I  have  found  the  pathetic  nerve  in  several  subjects  giving  offa branch, 

*  It  appears  to  me  that  there  is  a  communication  between  the  common  and  external  motor  nerves  in  the 
cavernous  sinus. 

t  I  have  seen  the  branch  for  the  inferior  rectus  arise  by  two  roots,  one  from  the  branch  for  tlie  internal 
rectus,  and  the  other  from  the  branch  for  the  inferior  oblique.  I  have  seen  the  branch  for  the  inferior  oblique 
give  off  a  supernumerary  branch  to  the  inferior  rectus.  Lastly,  sometimes  the  branches  for  the  inferior 
oblique  and  inferior  rectus  are  united,  so  that  the  inferior  division  of  the  third  nerve  was  subdivided  into  two 
branches  onlv 


THE    TKIGEMINAL    NERVES. 

which  united  with  another  from  the  ophthalmic  nerve  to  constitute  the  lachrymal  nerve 
This  anastomosis  took  place  at  the  bottom  of  the  orbit.  Another  and  well-founded  view  re- 
gards the  pathetic  nerve  and  the  ophthalmic  branch  of  Willis  as  forming  a  single  nerve  ;  in 
fact,  in  certain  subjects  they  interlace  so  intimately  that  it  is  impossible  to  separate  them. 
The  Branch  for  the  Tentorium  Cercbelli. — The  pathetic  nerve,  while  still  contained  in 
the  substance  of  the  external  wall  of  the  cavernous  sinus,  gives  off  a  branch  which  runs 
backward  in  the  substance  of  the  tentorium  cerebelli,  and  may  be  traced  as  far  as  the 
lateral  sinus,  near  which  it  divides  into  two  or  three  filaments.  In  several  subjects  I 
found  that  the  branch  for  the  tentorium  was  formed  by  a  twig  which  arose  from  the  oph- 
thalmic nerve,  became  applied  to  the  pathetic  nerve,  then  divergpd  from  it,-  and  passed 
backward  in  the  substance  of  the  tentorium.  It  appears,  then,  that  the  nerve  of  the  ten- 
toriarti  has  a  retrograde  course.* 

Function. — The  fourth  pair  of  nerves  is  intended  for  the  superior  oblique  muscle  only 
of  the  eye.  It  has  been  supposed  that  this  muscle  has  a  special  nerve  to  enable  it  to  ex- 
press certain  mental  emotions,  and  especially  love  and  pity ;  but,  as  Soemmering  remarks, 
it  exists  in  all  mammalia,  in  birds,  and  even  in  fishes. 

Camper  states  that  the  vital  functions  of  the  pathetic  survive  those  of  the  other  nerves, 
and  that  this  circumstance  influences  the  direction  of  the  eyes  in  dying  persons. 

According  to  Sir  C.  Bell,  the  pathetic  is  the  respiratory  nerve  of  the  eye.  Its  origin 
is  situated  at  the  highest  part  of  the  respiratory  tract.  According  to  the  same  physi- 
ologist, it  is  the  nerve  of  expression  ;  it  associates  the  muscles  of  the  eye,  and  estab- 
lishes certain  relations  between  the  eye  and  the  respiratory  system. 
The  Fifth  P.ur,  or  the  Trigeminal  Nerves. 
The  Twrvu$  trigeminus  (trifacial,  Chauss.,  5,  fig.  296),  which,  as  already  stated,  arises 
from  the  side  of  the  pons  Varolii  by  two  distinct  roots,  gains  the  upper  border  of  the  pe- 
trous portion  of  the  temporal  bone,  over  which  it  is  reflected,  and  near  the  apex  of  which 
there  is  a  depression  for  the  reception  of  the  nerve :  a  bridge-like  fold  of  the  dura  ma- 
ter converts  this  depression  into  a  canal.  The  nerve,  which  increases  in  width  as  it 
passes  over  the  upper  border  of  the  petrous  bone,  continues  to  get  wider  while  upon  the 
upper  surface  of  the  same  bone,  and  runs  downward,  forward,  and  outward  ;  its  fibres 
inunediately  spread  out  and  interlace  to  enter  the  concave  surface  of  a  grayish  semilu- 
nar enlargement  called  the  semilunar  or  Gasserian  ganglion.  All  the  fibres  of  origin  of 
the  fifth  nerve  do  not  assist  in  the  formation  of  this  ganglion ;  for,  on  reflecting  the  nerve 
from  within  outward,  a  flat  cord  {b,  fig.  299)  is  seen  below  the  ganglion,  and  giving  no 
fibre  to  it ;  and,  on  tracing  this  cord  upon  the  side  of  the  pons  Varolii,  it  is  found  to  con- 
sist of  the  small  root  of  the  fifth  nerve,  which  is  at  first  placed  on  the  inner  side  of  this 
nerve,  and  then  turns  round  it  to  gain  its  under  surface. 

This  very  remarkable  disposition  estabhshes  a  complete  analogy  between  the  fifth  cra- 
nial nerve  and  the  spinal  nerves,  which,  as  we  have  seen,  have  ganghonic  roots  (the 
posterior  roots)  and  non-ganglionic  roots  (the  anterior). 

The  Gasserian  ganglion  (behind  a  b  c,  fig.  298  ;  c,  fig.  299)  is  lodged  in  a  special  de- 
pression in  the  petrous  portion  of  the  temporal  bone  {fig.  296),  and  it  adheres  so  closely 
to  the  dura  mater  that  it  is  impossible  to  separate  the  ganglion  without  tearing  it.  From 
its  convex  surface,  which  is  directed  forward  and  outward,  proceed  three  plexiform  ner- 
vous trunks,  which  diverge  like  the  toes  of  a  bird  ;  these  are,  proceeding  from  before 
backward,  the  ophthalmic  nerve  of  Willis  (a,  figs.  296, 298,  &c),  the  superior  maxillary  nerve 
(i),  and  the  inferior  maxillary  nerve  (c) :  the  non-ganglionic  root  (J,  fig.  299)  of  the  fifth 
nerve  goes  directly  to  the  inferior  maxillary  division  (c)  of  the  nerve  :  the  opiithalmic  and 
the  superior  maxillary  divisions  often  arise  by  a  common  trunk.  Several  scattered  fila- 
ments are  given  ofl!"  from  the  three  divisions  of  the  2i^_._  398. 
nerve,  but  soon  join  them  again.  Communicating 
filaments  are  sometimes  seen  between  the  superi- 
or and  inferior  maxillary  divisions  as  these  latter 
enter  their  respective  foramina. 

The  ganglionic  nature  of  the  Gasserian  gangli- 
on cannot  be  doubted ;  for,  like  all  ganglia,  it  con- 
sists of  a  grayish,  pulpy  matter,  in  which  the  ner- 
vous fibres  are  spread  out,  and,  as  it  were,  entan- 
gled, to  enter  into  new  combinations. 

The  Gasserian  gangliont  gives  off"  several  fila- 
ments for  the  dura  mater,  which  may  be  traced 
into  the  substance  of  the  tentorium  cerebelli:  a 
<^rtain  number  of  filaments  appear  to  be  destined 

*  Arnold  has  described  the  branch  {f,Jig.  296)  for  the  ten- 
torium cerebelli,  which  is  derived  from  the  fifth  nerve,  and  not 
that  which  comes  from  the  pathetic. 

t  The  Gasserian  ganglion  might  serve  as  a  type  for  demon- 
strating the  structure  of  all  ganglia,  so  easy  is  the  separation 
of  the  gray  matter  and  white  fibres. 


NEUROLOGY. 

for  that  part  of  the  dura  mater  which  covers  the  petrous  portion  of  the  temporal  bone 
and  the  sphenoid  bone.  In  order  to  demonstrate  these  twigs,  the  dura  mater  must  bt 
previously  rendered  transparent  by  maceration  in  diluted  nitric  acid. 

The  Ophthalmic  Division  of  the  Fifth  J^erve. 
The  ophthalmic  nerve  of  Willis,  or  ophthalmic  division  of  the  fifth  nerve  (nerf  orbitaire, 
Winslow;  orbito-frontal,  Chauss.,  a,  fig.  296,  &c.),  is  the  highest  and  smallest  of  thfl 
three  divisions  :  it  passes  forward,  outward,  and  upward,  in  the  substance  of  the  exter- 
nal wall  of  the  cavernous  sinus,  in  which  situation  it  has  a  plexiform  structure.  It  is 
there  divided  into  an  external  branch,  called  the  lachrymal  nerve  {e,  fig.  296),  a  middle 
branch,  the  frontal  nerve  (continuation  of  a),  and  an  internal  hranch,  or  the  nasal  nerve ; 
these  three  branches  enter  the  orbit  through  different  parts  of  the  sphenoidal  fissure. 
Before  this  division,  the  ophthalmic  nerve  gives  off  a  retrograde  filament  (nervus  recur- 
rens  inter  laminas  tentorii,  Arnold,  f,fig.  296),  which  passes  backward,  closely  applied 
to  the  twig  furnished  by  the  pathetic  nerve  to  the  tentorium  cerebeUi,  and  running  paral- 
lel to  that  twig,  enters  the  tentorium. 

The  Lachrymal  or  Lachrymo-palpebral  Nerve. 

Dissection. — First  expose  the  nerve  in  the  orbit,  and  then  trace  it  backward  to  its  ori- 
gin. This  dissection  is  difficult,  unless  the  parts  have  been  macerated  in  diluted  nitric 
acid.     The  nerve  is  then  to  be  traced  into  the  substance  of  the  upper  eyelid. 

The  lachrymal  nerve  (c,  fig.  296),  the  smallest  of  the  three  branches  of  the  ophthalmic, 
comes  off  from  the  outer  side  of  that  nerve,  in  the  substance  of  the  external  wall  of  the 
cavernous  sinus,  where  it  is  difficult  to  discover  its  origin  and  course,  on  account  of  its 
intimate  adhesion  to  the  dura  mater ;  it  enters  the  orbit  through  the  narrowest  part  of 
the  sphenoidal  fissure,  runs  along  (below  s,fig.  300)  the  upper  border  of  the  external  rec- 
tus, passes  through  the  lachrymal  gland,  to  which  it  gives  several  filaments,  pierces  the 
fibrous  layer  of  the  upper  eyelid,  descends  vertically  within  that  eyelid,  between  its 
fibrous  layer  and  the  orbicularis  muscle,  and  divides  into  two  principal  cutaneous  fila- 
ments :  a  palpebral,  which  runs  along  the  lower  border  of  the  tarsal  cartilage  ;  and  an  as- 
cending temporal,  which  is  lost  in  the  integuments  upon  the  anterior  temporal  region. 
During  its  course,  the  lachrymal  nerve  gives  off  a  malar  branch,  which  may  be  regarded 
as  resulting  from  a  bifurcation  of  the  nerve.  This  branch  perforates  the  malar  bone, 
and  anastomoses  with  the  facial  nerve  upon  the  cheek.* 

The  lachrymal  branches,  properly  so  called,  are  extremely  small.  The  real  termination 
of  the  lachrymal  nerve  is  in  the  upper  eyelid,  and  hence  the  term  lachrymo-palpebral  has 
been  given  it. 

I  have  already  said  that  the  lachrymal  nerve  not  unfrequently  arises  by  two  filaments, 
one  of  which  is  derived  from  the  ophthalmic  of  the  fifth,  and  the  other  from  the  pathetic 
nerve  (Mr.  Swan  describes  this  as  the  usual  condition).  In  a  specimen  which  I  have 
now  before  me,  there  are  two  lachrymal  nerves,  one  of  which  arises  in  the  ordinary 
manner,  that  is  to  say,  from  the  ophthalmic  division  of  the  fifth,  while  the  other,  which 
is  external  and  smaller,  arises  both  from  the  pathetic  and  the  frontal  nerve.  These  two 
lachrymal  nerves  anastomose  with  each  other. 

The  Frontal  Nerve. 

The  frontal  nerve  (fronto-palpebral,  Chauss.)  may  be  regarded  as  the  continuation  of 
the  ophthalmic  (a,  fig.  296)  both  in  size  and  direction  ;  it  enters  the  orbit  at  the  highest 
and  broadest  part  of  the  sphenoidal  fissure,  together  with  the  pathetic  nerve. t 

It  passes  horizontally  forward,  between  the  periosteum  and  the  levator  palpebrae  su- 
perioris,  crossing  that  muscle  at  an  acute  angle,  and  divides  at  the  bottom  of  the  orbit 
into  two  unequal  branches,  which  do  not  diverge  until  they  reach  the  front  of  that  cavity  ; 
these  are  the  internal  frontal  and  the  external  frontal.X 

The  External  Frontal  or  Supra-orbital  Nerve  (r,figs.  296,  &c.). — This  is  larger  than  the 
internal  branch ;  it  passes  out  of  the  orbit  through  the  supra-orbital  foramen,  and  ex- 
pands into  ascending  or  frontal,  and  descending  or  palpebral  branches.  The  palpebral 
branches  are  very  numerous,  and  descend  vertically  in  the  substance  of  the  upper  eye- 

*  Authors  speak  of  a  filament  from  the  lachrymal  nerve  which  anastomoses  with  the  superior  maxillary 
nerve  near  the  anterior  extremity  of  the  infra-orbital  fissure.     I  have  never  seen  this  filament. 

[Before  reaching  the  lachrymal  gland,  the  lachrymal  nerve  may  give  off  one  or  two  communicating  filaments, 
to  join  the  temporal  filaments  of  the  orbital  branch  (t,fig.  300)  of  the  superior  maxillary  nerve,  before  these 
latter  perforate  the  outer  wall  of  the  orbit.] 

t  The  orbital  nerves  which  enter  the  sphenoidal  fissure  are  divided  into  two  sets  :  those  which  pass  thro'igh 
the  fibrous  ring  of  the  external  rectus,  namely,  the  common  motor  nerve,  the  nasal  branch  of  the  ophthalmic, 
and  the  external  motor  nerve  ;  and  those  which  pass  above  and  to  the  outer  side  of  the  preceding,  immediately 
below  the  lesser  ring  of  the  sphenoid  bone,  between  the  periosteum  and  the  superior  rectus,  namely,  the  fron- 
tal branch  of  the  ophthalmic,  the  pathetic,  and  the  lachrymal  branch  of  the  ophthalmic  ;  the  latter  nerve  pass- 
es separately  through  the  sphenoidal  fissure. 

X  Not  unfrequently  a  third  branch  arises  from  the  inner  side  of  the  frontal  nerve  ;  this  might  be  called  the 
fronto-nasal ;  it  passes  obhquely  inward  and  forward,  crosses  over  the  superior  oblique,  anastomoses  with  the 
external  nasal  nerve,  emerges  from  the  orbit  below  the  pulley  for  the  tendon  of  the  superior  oblique,  and  ter- 
minates with  the  external  nasal  nerve  in  the  upper  eyelid.  [This  fronto-nasal  branch  may  arise  from  the  in- 
ternal frontal  nerve.] 


THE    NASAL    NERVE.  829 

lid  ;  one  of  these  branches  runs  horizontally  outward  under  the  orbicularis  palpebrarum, 
to  anastomose  with  the  branches  of  the  facial  nerve.  The  frontal  hraiKhes  are  generally 
two  in  number,  an  external  and  an  internal.  They  form  the  true  continuation  of  the  ex- 
ternal frontal  nerve,  which  almost  always  bifurcates  as  it  passes  through  the  supra-orbi- 
tal foramen ;  they  are  reflected  upward ;  the  external,  which  is  the  larger,  passes  between 
the  frontal  muscle  and  the  periosteum ;  the  internal  {h,  Jig.  285)  lies  between  the  muscle 
and  the  skin  ;  they  both  run  somewhat  obliquely  upward  and  outward,  spread  out  into 
ramifications,  which  diverge  from  each  other  at  acute  angles,  and  may  be  traced  as  far 
as  the  lambdoidal  suture.  Almost  all  these  ramifications  are  distributed  to  the  skin. 
Some  of  them  are  periosteal,  and  these  require  for  their  proper  demonstration  that  the 
parts  should  be  macerated  in  diluted  nitric  acid :  it  is  doubtful  whether  any  of  them  ter- 
minate in  the  frontal  portion  of  the  occipito-frontalis  muscle.  In  some  subjects  there  is 
a  very  remarkable  osseous  frontal  branch,  which  enters  an  opening  in  the  supra-orbital  fo- 
ramen, and  passes  along  a  canal  formed  in  the  substance  of  the  frontal  bone ;  it  as- 
cends vertically  like  the  canal,  gives  off  a  succession  of  small  periosteal  filaments,  and  at 
length,  emerging  from  the  canal  opposite  to  the  frontal  eminence,  becomes  sub-cutaneous. 

The  Internal  Frontal  or  Supra-trochlear  Nerve  is,Jigs.  296,  301). — This  is  almost  always 
smaller,  but  is  sometimes  as  large  as  the  external  frontal ;  its  size  appears  to  me  to  be 
inversely  proportioned  to  that  of  the  external  nasal  and  external  frontal  nerves  togeth- 
er ;  it  is  often  divided  into  two  branches  ;  it  passes  out  of  the  orbit  between  the  supra- 
orbital foramen  and  the  pulley  of  the  superior  oblique  (hence  it  is  called  the  supra-troch- 
lear nerve),  and  divides  into  ascending-  or  frontal  filaments,  which  ramify  in  all  that  portion 
of  the  integuments  of  the  forehead  which  lies  between  the  branches  of  the  right  and  left 
external  frontal  nerves,  and  into  descending  or  palpebral  and  nasal  filaments,  which  de- 
scend vertically  ;  the  former  set  in  the  upper  eyelid,  and  the  latter  upon  the  dorsum  of 
the  nose,  where  they  anastomose  with  the  branches  of  the  nasal  nerve.* 

When  there  are  two  internal  frontal  nerves,  the  inner  one  of  them  enters  a  fibrous 
ring  formed  in  the  upper  part  of  the  pulley  for  the  superior  oblique,  and  divides  into  pal- 
pebral and  nasal  twigs,  while  the  outer  one  supplies  the  frontal  filaments.  This  outer 
nerve  sometimes  perforates  the  orbital  arch  from  behind  forward  in  a  special  canal :  I 
have  seen  it  pass  from  without  inward  to  enter  the  frontal  sinus,  then  run  along  the  an- 
terior wall  of  the  sinus,  and  finally  emerge  through  a  special  foramen  at  the  side  of  the 
nasal  eminence.  This  nerve  gave  no  branch  in  the  sinus,  although  it  was  situated  be- 
tween its  anterior  wall  and  the  lining  membrane. 

I  have  seen  the  frontal  nerve  divided,  from  its  entrance  into  the  orbit,  into  four  branch- 
es, of  which  the  two  outer  ones  corresponded  to  the  external  frontal,  and  the  two  inner 
ones  to  the  internal  frontal  nerve. 

The  Nasal  Nerve. 

Dissection. — The  orbital  portion  of  this  nerve  is  easily  exposed  between  the  optic  nerve 
and  the  superior  rectus.  The  external  nasal  branch  can  also  be  easily  traced  upon  the 
frontal  region.  In  order  to  see  the  internal  nasal  branch  in  the  corresponding  nasal  fos- 
sa, an  antero-posterior  vertical  section  of  the  head  must  be  made  on  one  side  of  the  sep- 
tum nasi ;  this  section  will  also  serve  for  the  demonstration  of  all  the  deep  nerves  of  the 
face. 

The  nasal  nerve  (above  t,fig.  301),  which  is  intermediate  in  size  between  the  other 
two  branches  of  the  ophthalmic,  viz.,  the  frontal  and  lachrymal  nerves,  arises  from  the 
inner  side  of  the  ophthalmic,  sometimes  even  as  that  nerve  is  entering  the  cavernous  si- 
nus ;  it  is  at  first  applied  to  the  inner  side  of  the  ophthalmic  nerve,  and  then  to  the  outer 
side  of  the  common  motor  nerve,  together  with  which  it  enters  the  orbit,  passing  be- 
tween the  superior  and  inferior  branches  of  that  nerve.  It  then  runs  inward  and  for- 
ward, crosses  obliquely  over  the  optic  nerve,  passes  below  the  superior  rectus,  then  be- 
low the  superior  oblique,  gains  the  internal  wall  of  the  orbit,  and  divides,  near  the  upper 
border  of  the  internal  rectus,  into  two  branches,  named  the  internal  and  the  external  na- 
sal nerve. 

Before  its  entrance  into  the  orbit,  the  nasal  nerve  gives  off  a  long  and  slender  filament 
(sometimes  two),  which  enters  the  ophthalmic  ganglion ;  it  also  furnishes  one  or  more 
ciliary  nerves,  which  run  on  the  inner  side  of  the  optic  nerve,  and  are  distributed  like 
the  ciliary  nerves  derived  from  the  ophthalmic  ganglion. 

The  external  nasal  nerve  (palpebral,  Chauss.).  This  branch  it,Jigs.  296,  301)  runs  for- 
ward, following  the  original  direction  of  the  nerve  below  the  superior  oblique,  and  emer- 
ges from  the  orbit  by  passing  under  the  cartilaginous  pulley  for  the  tendon  of  that  mus- 
cle (infra-trochlearis  nerve,  Arnold)  •  it  is  sometimes  joined  by  that  division  of  the  fron- 
tal nerve  which  I  have  named  the  fronto-nasal  (note,  p.  828),t  and  divides  into  the  fol- 
lowing branches  :  palpebral  filaments,  which  run  downward  and  outward  in  the  orbicu- 
laris palpebrarum,  and  form  anastomotic  arches  at  the  free  margin  of  the  upper  eyelid  ; 
a  great  number  of  nasal  twigs,  which  pass  upon  the  dorsum  of  the  nose,  and  anastomose 

*  [The  supra-trochlear  nerve  supplies  filaments  to  the  cornigator  sapercilii,  and  to  the  orbicularis.! 

t  I  hare  seen  the  external  nasal  nerve  give  off  a  branch  which  ran  inward,  anastomosed  with  the  fronto-na- 
nal,  perforated  the  roof  of  the  orbit,  ran  for  about  an  inch  beneath  the  dnrn  mater,  pcrfonited  the  frontal  bonf 
ab)ve  and  to  the  outer  side  of  the  frontal  sinus,  and  was  distributed  to  t'l  ■  -i';ui  up'i;i    'i  ■  '•>rfhead. 


S30  NECROLOGY. 

with  the  filaments  of  the  facial  nerve,  which  accompany  the  angular  vein ;  ani  frontal 
twigs,  which  anastomose  with  those  of  the  internal  frontal  nerve.* 

The  Internal  Nasal  or  Ethmoidal  Nerve  (u,  fig.  296). — The  course  of  this  nerve  is  very 
remarkable.  It  enters  the  anterior  internal  orbital  canal,  which  conducts  it  into  the  eth- 
moidal groove,  on  the  internal  surface  of  the  basis  cranii  ;t  it  is  then  reflected  forward 
upon  the  side  of  llie  crista  gaili,  passes  through  the  ethmoidal  fissure  into  the  corre- 
sponding nasal  fossa,  becomes  sensibly  increased  in  size,  and  divides  into  two  filaments, 
in  internal,  or  nerve  for  the  septum,  and  an  external,  or  naso-lobar  nerve. 

The  internal  filament,  or  anterior  nerve  of  the  teptum  nasi  {a,  fig.  297),  enters  the  fibro- 
mucous  membrane  upon  the  anterior  part  of  the  septum,  and  divides  into  several  very 
slender  filaments,  which  may  be  traced  below  the  middle  of  the  septum. 

The  external  filament,  or  nerve  of  the  external  wall  of  the  nasal  fossa  (u,  fig.  299),  runs 
along  the  anterior  border  of  the  septum,  and  divides  into  two  terminal  filaments,  one  of 
which  passes  upon  the  fore  part  of  the  external  wall  of  the  nasal  fossa,  and  ramifies  upon 
the  turbinated  bones  ;  while  the  other  and  larger  filament  (e,  naso-lobaire,  Chauss.)  fol- 
lows the  original  course  of  the  nerve,  and  passes  behind  the  nasal  bone,  which  is  mark- 
ed with  a  groove,  and  frequently  even  by  a  canal  for  the  reception  of  the  nerve ;  from 
this  latter  filament  several  twigs  proceed,  which  perforate  the  nasal  bone  more  or  less 
obliquely,  and  are  distributed  to  the  skin  of  the  nose ;  having  reached  the  lower  border 
of  the  nasal  bone,  it  passes  forward,  increasing  in  size,  through  the  fibrous  tissue  which 
unites  the  bone  to  the  lateral  cartilage  of  the  nose,  and  then  ramifies  in  the  skin  cover- 
ing the  ala  and  lobe  of  the  nose,  where  I  have  seen  it  anastomose  with  the  facial  nerve. 

While  within  the  cavity  of  the  cranium,  the  internal  nasal  nerve  lies  beneath  the  dura 
mater,  and  is  perfectly  distinct  from  the  olfactory  nerve,  with  which  it  never  anastomoses. 

The  Ophthalmic  Ganglion  and  its  Branchcs.X 
Dissection. — The  ophthalmic  ganglion  may  be  exposed  in  several  ways  :  for  example, 
♦jither  in  dissecting  the  branch  given  by  the  common  motor  nerve  to  the  inferior  oblique 
anuscle,  or  directly  by  removing  the  adipose  tissue  between  the  external  rectus  and  the 
»ptic  nerve.  The  long  branch  from  the  nasal  nerve  to  the  ophthalmic  ganglion  and  the 
;iliary  nerves  can  also  be  exposed  with  the  greatest  ease. 

The  ophthalmic  or  ciliary  ganglion  (behind  i,fig.  298)  is  a  small,  grayish,  and  flattened 
enlargement,  of  a  lenticular  form  (the  lenticular  ganglion),  applied  to  the  outer  side  of  the 
optic  nerve,  and  situated  about  two  or  three  lines  from  the  optic  foramen,  in  the  midst 
of  a  great  quantity  of  adipose  tissue,  which  renders  its  dissection  difficult.  It  varies 
much  in  size,  and  sometimes  consists  of  a  simple  miliary  enlargement,  which  forms  a 
point  of  origin  and  termination  for  a  certain  number  of  nerves.  For  the  convenience  of 
description,  this  ganglion  is  said  to  have  four  angles,  two  posterior  and  two  anterior  ; 
by  its  posterior  and  superior  angle  it  receives  a  long  slender  branch  {its  long  root),  given 
off  from  the  nasal  nerve  while  still  contained  within  the  cavernous  sinus.  Not  unfre- 
quently  a  second  long,  but  extremely  slender  root,  is  furnished  by  the  nasal  nerve  to  the 
ophthalmic  ganglion.  By  its  posterior  and  inferior  angle  it  receives  a  short,  thick  branch, 
which  comes  from  the  inferior  division  of  the  common  motor  nerve  {its  short  root).  From 
its  two  anterior  angles  it  gives  off  two  small  bundles  of  nerves,  named  the  ciliary  nervet 
{i,  fig.  298  ;  x,  fig.  301).  Lastly,  the  ophthalmic  ganglion  has  a  ganglionic  or  soft  root,  or, 
rather,  a  communicating  filament,  between  this  ganglion  and  the  superior  cervical  gan- 
glion of  the  sympathetic ;  this  soft  root  arises  frohi  the  cavernous  plexus,  and  passes 
.■sometimes  to  the  long  or  nasal  root  of  the  ophthalmic  ganglion,  and  sometimes  to  the 
ophthalmic  ganglion  itself 

The  ciliary  nerves  are  remarkable  for  their  tortuous  course,  in  which  respect  they  re- 
semble the  ciliary  arteries ;  and  also  for  being  collected  into  two  bundles,  the  one  supe- 
rior, which  is  generally  composed  of  four  filaments,  and  the  other  inferior,  composed  of 
five  or  six.  The  ciliary  nerves  do  not  anastomose  before  they  reach  the  globe  of  the 
eye,  with  the  exception,  however,  of  the  ciliary  nerve,  which  is  derived  directly  from 
the  nasal  nerve,  and  which  anastomoses  with  an  inferior  ciliary  nerve  from  the  ophthal- 
mic ganglion.  Having  reached  the  sclerotic,  the  ciliary  nerves  perforate  the  coat  more 
or  less  obliquely,  around  the  entrance  of  the  optic  nerve,  excepting  two  or  three,  which 
enter  the  globe  of  the  eye  near  the  attachment  of  the  muscle ;  after  having  perforated 
the  sclerotic,  they  become  flattened  or  riband-shaped,  and  run  forward  {a,  fig.  242)  par- 
allel to  each  other,  between  the  sclerotic  and  the  choroid  coats,  slightly  adhering  to  the 
former  of  these  membranes,  on  which  grooves  exist  for  their  reception ;  on  approaching 
the  ciliary  circle  or  ligament  (h),  they  bifurcate,  and  divide  into  filaments,  which  anasto- 
mose with  the  neighbouring  filaments,  and  appear  to  be  lost  in  the  ciliary  circle,  which 

*  [It  also  supplies  branches  to  the  lachrymal  sac  and  caruncula,  and  to  the  parts  of  tha  inner  canthns.] 
t  Not  unfrequently  the  internal  nasal  nerve,  while  within  the  ethmoidal  groove,  gives  off  a  recurrent  net* 
vous  twig,  which  enters  the  orbit  by  a  small  canal,  in  front  of  the  anterior  internal  orbital  canal,  and  anasto- 
moses with  the  external  nasal  or  infra-trochlear  nerve.  I  have  seen  this  small  nerve  anastomose  with  the 
tronto-nasal  branch,  which  I  have  already  described  (note,  p.  828)  as  an  unusual  branch  of  the  frontal  nerve. 
t  The  connexions  of  the  ophthalmic  ganglion  with  the  nasal  nerve,  as  well  as  with  the  common  motor  nerve, 
have  induced  me  to  describe  it  here. 


SUPERIOR    MAXILLARY   DIVISION    OP    THE    FIFTH    NERVE.  831 

has  been,  and  not  without  some  reason,  considered  by  modern  anatomists  as  a  nervous 
ganglion,  ganglion  annulare  (annulus  gangliformis  seu  ganglion  annulare,  Sammering).  I 
have  seen  some  of  these  ciliary  nerves  pass  through  the  ciliary  circle  and  enter  the  iris ; 
they  are  not  distinctly  seen  to  enter  the  ciliary  processes.* 

The  Superior  Maxillary  Division  of  the  Fifth  Merve. 

Dissection. — Saw  through  the  zygomatic  arch,  turn  down  the  masseteric  muscle,  and 
remove  the  roof  of  the  orbit ;  first  dissect  the  lachrymal,  malar,  and  temporal  twigs  of 
the  orbital  branch  of  the  nerve  ;  then  clean  out  the  orbital  cavity,  remove  the  upper  wall 
of  the  zygomatic  fossa  to  reach  the  spheno-maxillary  fossa  by  means  of  two  cuts  joined 
at  an  acute  angle  in  the  foramen  rotundum.  Detach  the  origins  of  the  pterygoid  mus- 
cles ;  lastly,  trace  the  nerve  into  the  infra-orbital  canal  and  on  the  face. 

The  superior  maxillary  nerve  Q),figs.  298,  300,  301),  the  second  or  middle  division  of 
the  fifth  nerve,  both  in  position  and  size,  runs  forward  to  enter,  after  a  very  short  course, 
the  foramen  rotundum,  by  which  it  is  conducted  into  the  spheno-maxillary  fossa  ;  from 
thence  it  passes  into  and  traverses  the  whole  length  of  the  infra-orbital  canal,  where  it 
is  named  the  infra-orbital  nerve  (/) ;  having  reached  the  fore  part  of  that  canal,  it  bends 
downward,  and  ramifies  in  the  cheek.  It  is  plexiform  at  its  origin  and  in  the  foramen 
rotundum,  but  is  fasciculated  throughout  the  rest  of  its  course. 

Its  collateral  branches,  taken  in  the  order  of  their  origin,  are  the  orbital  nerve  ;  certain 
nerves  which  are  given  off  from  the  enlargement  called  Meckel's  ganglion,  namely,  the 
palatine,  spheno-palatine,  and  vidian  or  pterygoid  nerves ;  the  posterior  dental  nerves, 
and  the  anterior  dental  nerve  ;  lastly,  several  small  filaments  come  off  either  from  the 
ganglion  of  Meckel  or  from  the  superior  maxillary  nerve  itself,  and,  surrounding  the  in- 
ternal maxillary  artery,  assist  in  the  formation  of  its  plexus. 

The  Orbital  Nerve. 
This  branch  [t,  jig.  300)  comes  off  immediately  in  front  of  the  foramen  rotundum,  from 
the  upper  side  of  the  superior  maxillary  nerve,  passes  through  the  spheno-maxillary  fis- 
sure, along  which  it  proceeds  to  enter  the  orbit ;  it  then  runs  along  the  floor  of  tl>e  orbit, 
and  divides  into  two  branches :  the  one  ascending,  the  lachrymal  branch  of  the  orbital 
nerve,  which  enters  the  lower  surface  of  the  lachrymal  gland,  anastomoses  with  the 
lachrymal  branch  (s)  of  the  ophthalmic  nerve  (a),  and  sends  off  some  branches  to  the 
upper  eyelid,  near  its  external  angle  ;  the  other  branch  is  the  temporo-malar,  which  pass- 
es horizontally  forward,  enters  a  small  canal  in  the  malar  bone,  and  subdivides  into  a 
malar  filament,  which  perforates  the  bone,  and  is  distributed  to  the  skin  upon  the  malar 
region,!  and  a  temporal  filament,  which  perforates  the  orbital  portion  of  the  malar  bone, 
and  dips  into  the  anterior  part  of  the  temporal  muscle,  in  which  it  anastomoses  with  the 
anterior  deep  temporal  nerve,  a  branch  of  the  inferior  maxillary.  I  have  sometimes 
seen  two  temporal  filaments  pass  through  the  malar  bone  at  two  different  points.^ 

The  Spheno-palatine  Ganglion  and  its  Branches. 

After  having  given  off  the  orbital  nerve,  and  while  it  is  still  contained  in  the  spheno- 
maxillary fossa,  the  superior  maxillary  nerve  gives  off  from  its  lower  side  a  thick  branch, 
frequently  two,  and  occasionally  several  branches,  from  which  a  great  number  of  diver- 
ging nerves  immediately  proceed ;  these  are  the  three  palatine  nerves,  the  spheno-pala- 
tine nerves,  and  the  vidian  nerve  ;  at  the  point  where  these  nerves  diverge  is  found  an 
enlargement  which  the  elder  Meckel,^  whose  name  is  connected  with  the  description  of 
the  fifth  pair,  regarded  as  a  ganghon,  and  which  is,  therefore,  called  Meckel's  ganglion, 
or  the  spheno-folatine  ganglion  (situated  before  s,fig.  299  ;  below  b,fig.  301). 

In  a  certain  number  of  cases,  I  have  sought  in  vain  for  the  ganglionic  structure  in  this 
enlargement,  i.  e.,  for  gray  matter  with  white  filaments  scattered  through  it.  It  appear- 
ed then  to  be  nothing  more  than  the  common  trunk  or  starting-point  of  a  great  number 
of  nerves  ;  in  the  majority  of  cases,  however,  a  quantity  of  gray  matter  certainly  exists, 
but  is  so  arranged  that  the  nerves  may  generally  be  traced  quite  through  the  enlarge- 
ment, so  that  they  clearly  are  not  given  off  from  the  ganglion  itself,  but  come  directly 
from  the  superior  maxillary  nerve.  II 

*  Tiedemann,  from  the  results  of  observations  in  comparative  anatomy,  believes  that  the  arteries  vv'hich  ram- 
ify in  the  retina  are  accompanied  by  very  delicate  nervous  filaments,  derived  from  the  ophthalmic  ganglion  and 
the  ciliary  nerves  :  he  has  seen  a  nervous  filament  penetrate  the  optic  nerve  with  the  arteria  centralis  retinje  ; 
and  he  states  that  the  ciliary  arteries  are  accompanied  by  very  delicate  nervous  filaments,  which  he  has  tra- 
ced into  the  retina  as  far  as  the  zone  of  Zinn.  Tiedemann  also  says  that  he  has  seen,  only  once,  it  is  true,  a 
rather  large  nervous  filament  proceed  from  Meckel's  ganglion,  and  join  the  thick  and  short  branch  which  is 
pveu  oflFfrom  the  third  pair  to  assist  in  the  formation  of  the  ophthalmic  ganglion. 

t  It  is  said  that  this  twig  anastomoses  with  the  facial  nerve  in  the  malar  region  ;  I  have  never  been  fortu- 
nate enough  to  discover  this  anastomosis. 

X  [Both  of  these  temporal  filaments  maybe  joined  by  communicating  twigs  from  the  lachrymal  nerve  withia 
the  orbit ;  one  of  them  anastomoses  with  the  anterior  deep  temporal  nerve,  as  above  mentioned  ;  the  other, 
having  entered  the  temporal  fossa  through  the  malar  bone,  ascends  on  the  temporal  surface  of  that  bone,  turns 
outward,  perforates  the  temporal  fascia  about  an  inch  above  the  zygoma,  anastomoses  with  filaments  of  the 
facial  nerve,  and  of  the  auriculo-temporal  branch  of  the  inferior  maxillary  nerve,  and  is  lost  in  the  skin  on  the 
temple.]  t)  Mem.  de  I'Acad.  de  Berlin,  1749 

II  In  one  case  the  ganglion  of  Meckel  was  in  contact  with  the  internal  surface  of  the  superior  maxillary 
nerve      In  the  same  case  a  filament  proceeded  from  the  upper  part  of  the  ganglion,  and  joined  the  branch 


.flB  NEUROLOGY. 

I  shall  now  describe,  in  succession,  the  branches  which  proceed  from  Meckel's  ganglion. 

The  Palatine  Nerves. 
These  nBrves  {gg,fig-  299;  g,Jig.  301)  are  three  in  number:  an  anterior  palatine, 
which  is  the  largest,  a  posterior  palatine  [the  middle  of  some  authors],  which  is  the  next 
in  size,  and  an  intermediate  nerve  [the  posterior  of  some  authors],  which  is  the  smallest ; 
these  nerves  are  continuous  with  Meckel's  ganghon  ;  it  is  most  evident  that,  in  the 
greater  number  of  cases,  they  arise  directly  from  the  lower  part  of  the  superior  maxil- 
lary nerve. 

The  anterior  or  great  palatine  nerve  immediately  enters  the  posterior  palatine  canal, 
through  the  whole  length  of  which  it  passes,  and,  having  reached  the  lower  orifice  of 
that  canal,  is  reflected  forward,  and  terminates  by  bifurcating  on  the  hard  palate. 

During  its  course,  it  gives  off  an  inferior  nasal  branch  (lower  f,  Jig.  299),  which  is  dis- 
Fig.  299.  tributed  over  the  middle  meatus  and  the  middle  and  inferior 

turbinated  bones :  the  twig  for  the  inferior  turbinated  bone 
may  be  traced  to  the  fore  part  of  that  bone  ;  it  also  gives  off 
the  anterior  palatine,  and  several  small  twigs,  which  perfo- 
rate the  inner  wall  of  the  maxillary  sinus,  and  are  distributed 
to  the  last  molar  teeth  ;  lastly,  at  its  exit  from  the  posterior 
palatine  canal,  and  even  sometimes  while  yet  within  that 
canal,  it  sends  off  a  staphyline  branch,  which  spreads  into 
several  filaments,  all  of  which  run  backward  in  the  soft  pal- 
ate, and  divide  into  superior  filaments  distributed  to  the  mu 
cous  membrane  on  the  nasal  surface  ;  and  inferior,  which  run  beneath  the  mucous  mem- 
brane on  the  buccal  surface  of  the  soft  palate.  Of  the  two  terminal  branches  of  the  an- 
terior palatine  nerve,  both  of  which  occupy  the  hard  palate,  the  external  runs  near  the 
alveolar  border,  and  the  internal  near  the  median  line  ;  they  enter  into  the  midst  of  the 
glandular  layer  of  the  palate,  and  are  ultimately  distributed  to  the  glands,  to  the  mucous 
membrane  of  the  hard  palate,  and  to  the  gums. 

The  posterior  [middle]  palatine  nerve,  the  next  in  size,  enters  a  special  canal :  on  es- 
caping from  which  it  passes  backward,  beneath  the  mucous  membrane  of  the  nasal  sur- 
face of  the  soft  palate,  to  which  it  is  distributed. 

The  same  is  the  case  with  the  intermediate  [posterior]  or  small  palatine  nerve,  which 
is  extremely  slender. 

I  have  seen  a  palatine  nerve  enter  the  maxillary  sinus,  run  beneath  its  lining  mem- 
brane, pass  vertically  through  the  maxillary  tuberosity  behind  the  last  molar  tooth,  and 
ramify  upon  the  hard  palate. 

The  Spheno-palatine  or  Posterior  Nasal  Nerves. 

Dissection. — ^Make  a  vertical  section  of  a  head,  previously  macerated  in  dilute  nitric 
acid,  strip  off  the  pituitary  membrane  lying  upon  the  septum  and  the  turbinated  bones, 
and  examine  the  nerves  from  the  internal  or  deep  surface  of  that  membrane. 

The  spheno-palatine  nerves  are  very  slender ;  they  enter  the  corresponding  nasal 
fossae  through  the  spheno-palatine  foramen,  and  have  been  traced  by  Scarpa  with  his 
customary  exactness.  They  are  all  situated  in  the  pituitary  membrane,  or,  rather,  be- 
tween the  periosteum  and  the  mucous  membrane,  and  cannot  be  readily  seen  until  this 
fibro-mucous  membrane  has  been  removed  from  the  bones  which  it  covers  ;  the  nervous 
filaments  are  then  seen  through  the  semi-transparent  fibrous  layer.  For  this  purpose, 
preparations  macerated  in  diluted  nitric  acid  are  indispensable.  The  spheno-palatine 
nerves  are  distributed  to  the  septum  nasi  and  the  external  wall  of  the  corresponding  na- 
sal fossa ;  they  are  divided  into  internal  and  external. 

There  is  only  one  internal  spheno-palatine  nerve,  viz.,  the  nerve  of  the  septum  nasi,  or 
ine  naso-palatine  of  Scarpa  {b,fig.  297) ;  it  passes  inward,  in  front  of  the  sphenoidal  si- 
nus, and  below  the  orifice  of  that  sinus,  to  gain  the  septum  nasi ;  it  is  then  directed  at 
first  almost  vertically  downward,  but  afterward  almost  horizontally  forward,  as  far  as 
the  superior  orifice  of  the  anterior  palatine  canal,  which  it  enters,  and  then  passes  into 
a  special  canal,  quite  distinct  from  the  anterior  palatine  canal,  and  parallel  to  the  one 
for  the  naso-palatine  nerve  of  the  opposite  side.  According  to  M.  Hippolyte  Cloquet, 
the  two  naso-palatine  nerves  terminate  in  the  upper  part  of  a  ganglion,  which  he  calls 
the  naso-palatine,  and  do  not  reach  the  mouth ;  but  in  some  researches  which  I  have 
made  on  the  subject,  I  have  failed  in  detecting  this  ganglion. t 

The  nerves  can  be  distinctly  seen  to  enter  the  mucous  membrane  of  the  hard  palate 
behind  the  incisor  teeth,  and  upon  that  prominence  of  the  mucous  membrane  against  which 
the  point  of  the  tongue  is  so  often  applied.  I  have  never  seen  any  anastomoses  either 
between  the  two  naso-palatine  nerves,  or  between  these  and  the  anterior  palatine  nerves. 

given  by  the  external  motor  nerve  to  the  sympathetic.     I  have  not  been  able  to  discover  the  filaments  which 
are  said  to  establish  a  communication  between  Meckel's  ganglion  and  the  optic  nerve. 

t  I  find  that  it  is  stated  by  Arnold,  whom  I  have  so  often  quoted,  because  his  works  are  above  all  praise  fijr 
their  rigorous  accuracy,  that  the  spheno-palatine  ganglion  docs  not  exist ;  and  he  observes,  with  reason,  that 
the  subjoined  description  of  M.  Hippolyte  Cloquet  is  very  imperfect.  "  It  consists  of  a  small ,  reddish,  fungous 
mass,  rather  hard,  as  if  fibro-cartilaginous,  and  surrounded  by  adipose  cellular  tissue  " 


THE    PTERYGOID    NERVE,    ETC.  833 

Anatomists  are  not  agreed  as  to  whether  the  naso-palatine  nerve  gives  off  any  fila- 
ments upon  the  septum.  I  have  failed  in  detecting  any  ramification  of  the  nerve  in  a 
great  number  of  preparations,  in  which  tlie  pituitary  membrane  had  been  rendered  trans- 
parent by  long  maceration  in  diluted  nitric  acid.  Rather  frequently  a  filament  was  given 
off  from  the  upper  part  of  the  nerve,  and  then  joined  it  again.  Three  times  only  did  I 
observe  a  twig  running  upward  from  the  anterior  part  of  the  nerve. 

The  external  spheno-palatine,  or  superior  nasal  nerves  (upper  /,  fig.  299),  so  called  to 
distinguish  them  from  thfe  inferior  nasal  branch  of  the  anterior  palatine  nerve,  are  three 
or  four  in  number  ;  they  are  directed  vertically  along  the  back  part  of  the  outer  wall  of 
the  corresponding  nasal  fossa,  and  spread  out  into  filaments,  which  extend  over  the  tur- 
binated bones  and  the  meatus  ;  these  filaments  can  only  be  seen  from  the  deep  surface 
of  the  pituitary  membrane.* 

I  have  never  been  able  to  find  the  anastomoses  between  the  internal  and  external 
spheno-palatine  nerves  and  the  divisions  of  the  olfactory  nerve,  which  are  admitted  by 
some  anatomists. 

The  Vidian  or  Pterygoid  Nerve. 

The  vidian  nerve  {v,figs.  300,  301)  arises  from  the  back  part  of  Meckel's  ganglion,  and 
enters  the  vidian  or  pterygoid  canal,  after  emerging  from  which  it  perforates  the  carti- 
laginous plate  of  the  foramen  lacerum  anticus,  and  divides  into  a  superior  cranial  branch, 
the  great  superficial  petrosal  nerve,  and  an  inferior,  deep,  or  carotid  branch.  The  subdivis- 
ion of  the  pterygoid  nerve  often  occurs  at  its  origin  from  Meckel's  ganglion. 

The  inferior  or  carotid  branch,  which  is  much  larger  than  the  superior,  forms  the  con- 
tinuation of  the  nerve :  it  enters  the  carotid  canal,  and  is  applied  to  the  outer  side  of 
the  carotid  artery,  where  it  anastomoses  with  the  nerves  which  establish  a  communica- 
tion between  the  superior  cervical  ganglion  and  the  external  motor  nerve  of  the  eye, 
and  assists  in  the  formation  of  the  carotid  plexus  ;  a  flattened  gangliform  enlargement 
is  seen  at  the  point  of  anastomosis.  I  have  sometimes  seen  two  carotid  branches,  one 
of  which  was  very  small. 

The  superior  or  cranial  branch,  the  great  superficial  petrosal  nerve,  enters  the  cranium 
between  the  temporal  and  sphenoid  bones,  runs  backward  and  outward  {v,  fig.  296)  be- 
neath the  dura  mater,  in  a  groove  on  the  upper  surface  of  the  petrous  portion  of  the 
temporal  bone,  passes  through  the  hiatus  Fallopii  into  the  aqueductus  Fallopii  or  canal 
for  the  facial  nerve  (part  of  7),  and  anastomoses  with  that  nerve. t  I  say  that  it  anasto- 
moses, because  there  is  a  sort  of  fusion  of  the  two  nerves,  and  not  a  simple  juxtaposi- 
tion. The  branch  called  the  chorda  tympani,  which  comes  off  from  the  facial  nerve  at 
some  distance  from  the  point  of  fusion,  should  not  be  regarded  as  a  prolongation  of  the 
superficial  petrosal  nerve,  supposed  in  that  case  to  be  merely  applied  to  the  facial  nerve.t 

The  Posterior  Dental  Nerves. 

Dissection. — These  nerves  can  be  readily  seen  without  any  dissection  through  the 
bone,  when  this  is  rendered  transparent  by  nitric  acid.  They  must  be  examined  both 
from  the  external  surface  of  the  bone,  and  from  the  interior  of  the  sinus. 

The  posterior  dental  or  alveolo-dental  nerves  (e,figs.  298,  300,  301)  are  two  in  number, 
a  superior  and  an  inferior ;  sometimes  there  are  three ;  they  arise  from  the  superior 
maxillary  nerve,  sometimes  by  a  common  trunk,  sometimes  separately,  just  as  that 
nerve  is  about  to  enter  the  infra-orbital  canal :  they  run  forward  and  downward,  at  first 
in  contact  with  the  maxillary  tuberosity,  and  give  off  some  filaments  to  the  buccinator 
muscle,  and  to  the  gums,  and  some  which  are  distinctly  distributed  to  the  mass  of  fat  in 
the  cheek  ;  they  then  enter  certain  canals  in  the  substance  of  the  maxillary  tuberosity, 
and  become  flattened  or  riband-shaped. 

The  posterior  and  superior  dental  nerve  passes  from  behind  forward,  through  the  base 

*  Bock,  and  Arnold  after  him,  have  described,  under  the  name  of  the  pharyngeal  branch,  a  rather  large 
branch,  which  may  be  regarded  as  belonging  to  the  external  spheno-palatine  nerves  ;  it  enters  into  the  ptery- 
go-palatine  canal,  formed  between  the  under  surface  of  the  sphenoid  and  the  sphenoidal  process  of  the  palate 
bone,  passes  backward  and  inward,  and  divides  into  several  filaments,  which  are  distributed  to  the  upper  part 
of  the  pharynx.  [Some  of  these  superior  nasal  branches  are  said  to  supply  the  lining  membrane  of  the  pQS<.e- 
rior  ethmoidal  and  the  sphenoidal  sinuses.] 

t  I  have  seen  the  superior  branch  of  the  vidian  formed  by  three  very  distinct  filaments:  anatomists  are  still 
undecided  as  to  whether  the  inferior  or  carotid  branch  is  derived  from  the  ganglion  of  Meckel,  or  from  tlie  su 
perior  cervical  ganglion.  According  to  Arnold,  it  resembles  the  organic  system  of  nerves  in  its  colour,  soft- 
ness, and  structure.  I  cannot  coincide  in  this  opinion,  for  it  appears  to  me  that  the  cranial  and  carotid  branch, 
es  of  the  vidian  are  analogous  in  every  respect. 

t  Arnold,  who  regards  this  opinion  of  Hippolyte  Cloquet,  which  is  adopted  by  Hirsel,  as  erroneous,  states 
that,  at  the  junction  of  the  cranial  branch  of  the  vidian  with  the  facial  nerve,  there  is  a  gangliform  swelling, 
in  which  he  finds  some  analogy  to  the  inter- vertebral  ganglia,  and  which  he  considers  to  be  a  transition  be- 
tween a  gangliform  stalk  and  a  true  ganglion. 

According  to  Arnold,  the  superficial  or  cranial  branch,  and  the  deep  or  carotid  branch  of  the  vidian,  do  not 
come  from  a  common  trunk,  but  are  merely  juxtaposed,  and  are  distinct  throughout  their  entire  extent.  The 
carotid  branch  is  soft  and  reddish,  presents  all  the  characteristics  of  the  ganglionic  nerves,  and  is  intended  to 
establish  a  communication  between  the  superior  cervical  and  the  spheno-palatine  ganglion.  The  cranial  or  sui 
perficial  petrosal  branch,  on  the  contrary,  presents  all  the  characters  of  the  cerebro-spinal  nerves  ;  it  i«of  t 
white  colour  and  firm  consistence. 

5N 


834  NEUROLOGY. 

of  the  malar  eminence  of  the  superior  maxillary  bone,  and  anastomoses  on  a  level  with 
the  canine  fossa  with  a  filament  from  the  anterior  dental  nerve. 

The  posterior  and,  inferior  dental  nerve,  which  is  larger  than  the  preceding,  runs  in  a 
curved  direction  below  the  malar  eminence,  the  concavity  of  the  curve  being  directed 
upward,  and  anastomoses  with  the  posterior  and  superior  dental  nerve,  on  a  level  with 
the  canine  fossa.  No  filament  is  given  off  from  the  upper  side  of  these  nerves,  but  they 
give  off  a  great  number  of  filaments  downward,  which  anastomose,  and  form  a  series  of 
very  remarkable  meshes  or  areolae ;  these  meshes,  and  the  'dental  nerve  which  come 
from  them,  are  situated  within  the  substance  of  the  bone,  but  are  much  nearer  to  the 
sinus  than  to  the  outer  surface  of  the  bone.  It  is  from  these  meshes  that  the  extremely 
delicate  filaments  arise  which  form  the  dental  nerves  of  the  molars  and  bicuspids ;  their 
number  corresponds  to  that  of  the  fangs  of  these  teeth.* 

Some  filaments  evidently  terminate  in  the  substance  of  the  superior  maxillary  bone  ; 
no  other  bone  in  the  body  has  so  large  a  number  of  proper  filaments. 

The  Anterior  Dental  Nerve. 

The  anterior  dental  or  alveolo-dental  nerve  {j,fig.  298)  is  the  only  branch  given  off  by 
the  superior  maxillary  nerve  while  within  the  infra-orbital  canal  ;t  it  arises  about  five  or 
six  lines  from  the  anterior  orifice  of  that  passage.  It  is  so  large  that  it  may  be  regarded 
as  resulting  from  the  bifurcation  of  the  infra-orbital  nerve.  It  soon  enters  a  special  ca- 
nal formed  for  it  in  the  superior  maxillary  bone,  gives  off  on  the  outer  side  a  small 
branch  which  anastomoses  with  the  posterior  and  superior  dental  nerve,  passes  at  first 
horizontally  inward,  and  then  vertically  downward,  turning  round  the  margin  of  the  an- 
terior opening  of  the  corresponding  nasal  fossa,  and  is  reflected  upon  the  floor  of  that 
fossa ;  during  the  whole  of  this  course,  it  is  situated  within  the  substance  of  the  superior 
maxillary  bone ;  its  horizontal  portion  is  superficial,  and  its  vertical  portion  is  deep- 
seated,  having  merely  a  thin  bony  lamella  between  it  and  the  pituitary  membrane. 
Having  arrived  on  a  level  with  the  floor  of  the  nasal  fossa,  about  two  lines  from  its  an- 
terior opening,  it  expands  into  a  great  number  of  ascending  and  descending  filaments ;  the 
aseending  filaments  are  reflected  upward  within  the  anterior  nasal  spine,  where  they  ter- 
minate. They  appear  to  me  to  send  off  a  small  ramification  to  the  pituitary  membrane. 
The  descending  filaments  terminate  by  supplying  the  dental  nerves  for  the  incisor,  canine, 
and  first  bicuspid  teeth.  A  great  number  of  filaments  are  also  lost  in  the  substance  of 
the  bone. 

I  have  never  seen  any  filaments  from  the  dental  nerves  entering  the  membrane  of  the 
maxillary  sinus. 

The  Terminal  Branches  of  the  Superior  Maxillary  Nerve. 

Having  reached  the  anterior  orifice  of  the  infra-orbital  canal,  the  superior  maxillary 
nerve,  the  component  bundles  of  which  had  been  merely  in  juxtaposition,  immediately 
expands  {i,fig.  301)  into  a  pencil  of  diverging  filaments  beneath  the  levator  labii  supe- 
rioris.  These  filaments  {i,fig-  285)  may  be  divided  into  ascending  or  palpebral,  which 
pass  upward  and  outward  beneath  the  orbicularis  palpebrarum,  and  are  distributed  to  the 
skin  and  conjunctiva  of  the  lower  eyelid ;  a  great  number  of  internal  or  nasal  filaments, 
which  run  upon  the  side  of  the  nose,  and  are  distributed  to  the  skin  of  that  organ  ;  one 
of  them  runs  along  beneath  the  septum  ;  and,  lastly,  into  descending  or  labial  filaments, 
which  are  the  most  numerous,  and  which  enter  the  substance  of  the  upper  lip,  and  are 
distributed  to  the  skin  and  the  mucous  membrane  :  all  these  filaments,  and  especially  the 
labial,  interlace  and  anastomose  with  the  facial  nerve,  so  as  to  form  a  plexus,  named  the 
infra-orbital,  to  which  we  shall  return  in  describing  the  facial  nerve. 

I  have  seen  the  nasal  and  the  palpebral  filaments  arise  together  from  the  superior  max- 
illary nerve,  before  it  had  given  off  the  anterior  dental,  enter  a  special  canal  situated  on 
the  inner  side  of  the  infra-orbital  canal,  emerge  opposite  the  line  of  demarcation  between 
the  cheek  and  the  nose,  and  then  expand  into  their  nasal  and  palpebral  divisions ;  while 
the  labial  filaments  had  their  usual  arrangement. 

The  Inferior  Maxillary  Division  of  the  Fifth  J^erve. 
Dissection. — As  this  nerve  must  be  examined  both  upon  its  internal  and  its  external 
aspect,  it  must  be  dissected  in  both  directions.  An  antero-posterior  section  of  the  head 
in  the  median  line  will  enable  us  to  see,  on  the  internal  surface  of  the  nerve,  the  chorda 
tympani,  the  otic  ganglion,  and  the  origins  of  all  the  other  branches  which  come  from 
the  inner  side  of  the  inferior  maxillary  nerve,  viz.,  the  nerve  of  the  internal  pterygoid, 
the  lingual  nerve,  and  the  dental  nerve.  In  order  to  see  the  distribution  of  the  deep 
temporal,  the  masseteric,  the  buccal,  the  internal  pterygoid,  and  the  auriculo-temporal 
nerves,  the  inferior  maxillary  nerve  must  be  exposed  from  its  outer  side,  by  breaking 
down  the  zygomatic  arch,  reflecting  down  the  masseter,  which  is  to  be  detached  as  far 

*  In  those  molar  teeth  which  have  two  or  three  roots,  the  nervous  filaments  snbdiii'ide  and  anastomose  with 
each  other  in  the  substance  of  the  dental  pulp. 

t  Sometimes,  however,  I  have  seen  the  posterior  and  superior  dental  nerve  arise  within  the  infra-orbital 
'lanal. 


THE  DEEP  TEMPORAL  NERVE,  ETC.  835 

back  as  the  sigmoid  notch,  by  sawing  through  the  base  of  the  coronoid  process,  and 
turning  the  temporal  muscle  upward,  and  then  by  carefully  dividing  the  external  ptery- 
goid muscle,  through  which  the  buccal  nerve  passes. 

The  inferior  maxillary  nerve  (c,  figs.  296,  &c.),  the  most  posterior  and  the  largest  di- 
vision of  the  fifth  nerve,  passes  outward  and  a  little  forward,  and,  after  a  very  short 
course  within  the  cranium,  escapes  through  the  foramen  ovale  into  the  zygomatic  fossa, 
where  it  divides  successively  into  seven  branches.  The  non-ganglionic  root  (i,  fig.  299) 
of  the  fifth  nerve  is  connected  exclusively  with  the  inferior  maxUlary  division  (c)  of  its 
other  root,  beneath  which  it  lies,  from  which  it  can  be  distinguished  by  not  having  a 
plexiform  structure,  with  which  it  is  not  blended  until  it  emerges  from  the  foramen  ovale. 
Of  the  seven  branches  of  the  inferior  maxillary  nerve,  three  are  external,  namely,  the  an- 
terior and  posterior  deep  temporal,  the  masseteric,  and  the  buccal ;  one  is  posterior,  name- 
ly, the  auriculo-temporal ;  one  is  internal,  the  internal  pterygoid  ;  and  two  are  inferior,  the 
lingual  or  gustatory,  and  the  inferior  dental.  These  nerves  may  also  be  divided  into  col- 
lateral branches,  including  the  first  five,  and  the  terminal  branches,  namely,  the  lingual  and 
the  inferior  dental ;  the  otic  ganglion,  described  by  Arnold,  is  connected  vidth  this  nerve.* 

The  Collateral  Branches  of  the  Inferior  Maxillary  Nerve. 

The  Deep  Temporal  Nerve. 

The  first  external  branch,  or  the  deep  temporal  -nerve,  arises  from  the  outer  side  of  the 
inferior  maxillary  nerve,  passes  horizontally  outward  and  forward  between  the  roof  of  the 
zygomatic  fossa,  with  which  it  is  in  contact,  and  the  eternal  pterygoid  muscle.  Having 
arrived  at  the  ridge  which  separates  the  temporal  from  the  zygomatic  fossa,  it  anasto- 
moses with  several  temporal  branches  derived  from  the  buccal  and  masseteric  nerves, 
and  forms  a  sort  of  plexus  with  them.  The  branches  which  emerge  from  this  plexus 
ascend  vertically  in  the  deep  layers  of  the  temporal  muscle,  in  which  most  of  them  ter- 
minate. 

Some  twigs  anastomose  with  the  temporal  filaments  derived  from  the  lachrymal  branch 
of  the  ophthalmic  nerve,  and  from  the  orbital  branch  of  the  superior  maxillary  nerve. t 
One  and  sometimes  two  filaments  perforate  the  temporal  fascia,  about  a  finger's  breadth 
above  the  zygomatic  arch,  and  then  ascend  beneath  the  skin,  to  anastomose  with  the 
auriculo-temporal  and  the  facial  nerves.t 

The  Masseteric  Nerve. 

The  second  external  branch,  or  the  masseteric  nerve,  arises  from  the  same  point  as  the 
last  nerve,  and  greatly  exceeds  it  in  size  ;  it  comes  off  at  an  acute  angle,  passes  horizon- 
tally backward  and  outward  in  contact  with  the  roof  of  the  zygomatic  fossa,  between  it 
and  the  external  pterygoid  muscle  ;  it  is  then  reflected  downward  over  the  upper  part  of 
that  muscle  to  gain  the  sigmoid  notch  of  the  lower  jaw,  upon  which  it  is  again  reflected, 
and  then  descends  vertically,  between  the  rcimus  of  the  jaw  and  the  masseter,  or,  rather, 
in  the  substance  of  the  deep  layers  of  that  muscle,  down  to  the  insertion  of  which  it  may 
be  traced.  During  its  course  along  the  upper  wall  of  the  zygomatic  fossa,  the  masse- 
teric nerve  gives  off  a  small,  deep  temporal  branch,  which  runs  along  the  periosteum, 
passes  into  the  temporal  fossa,  and  sends  off  an  articular  branch  to  the  temporo-max- 
illary  articulation. 

The  Buccal  or  Bucco-lahial  Nerve. 

The  third  external  branch  {g,  fig.  300),  the  buccal,  or,  rather,  the  bucco-lahial  nerve 
(Chauss.),  is  very  remarkable  on  account  of  its  size  and  the  extent  of  its  distribution, 
which  gives  it  some  resemblance  to  the  corresponding  portion  of  the  facial  nerve.  It 
arises  from  the  outer  side  of  the  inferior  maxillary  nerve,  by  one,  two,  and  sometimes 
three  roots,  which  perforate  the  external  pterygoid,  and  join  together  as  they  emerge  from 
that  muscle ;  from  thence  it  runs  downward  between  the  coronoid  process  of  the  lower 
jaw  and  the  tuberosity  of  the  upper  jaw,  gives  several  twigs  to  the  external  pterygoid 
muscle,  and  also  some  branches  to  the  temporal  muscle,  of  which  one  ascends  and  an- 
astomoses with  the  deep  temporal  nerve,  whUe  another  descends  and  is  distributed  to 
the  same  muscle,  near  its  insertion  into  the  coronoid  process  ;  the  buccal  nerve  itself 
sometimes  perforates  the  lowest  part  of  the  insertion  of  the  temporal  muscle,  and  having 
reached  the  back  part  of  the  buccinator,  it  expands  into  a  great  number  of  diverging 
branches,  like  the  facial  nerve. 

The  ascending  branches  are  distributed  to  the  skin  of  the  malar  and  buccal  regions  j 
one  of  them  forms  an  anastomic  arch  with  the  facial  nerve  behind  the  duct  of  Steno. 
This  anastomosis  is  very  remarkable.  The  middle  branches  pass  horizontally  forward 
on  a  level  with  the  commissure  of  the  lips,  and  terminate  in  the  skin  ;  several  of  them 
form  a  sort  of  plexus  around  the  inferior  coronary  artery  of  the  lip.  The  lowest  of  the 
descending  branches  pass  vertically  downward,  and  even  a  little  backward,  upon  the  outer 
surface  of  the  buccinator,  also  beneath  the  deep  surface  and  upon  the  outei"  surface  of 

*  We  sometimes  find  a  communicating  filament  between  the  superior  and  inferior  maxillary  nerves  imme- 
diately before  they  enter  their  respective  foramina. 
+  [There  is  hence  a  communication  between  the  branches  of  the  three  divisions  of  the  fifth  nerve.] 
i  [This  cutaneous  filament  is  one  of  the  temporal  filaments  of  the  orbital  branch  of  the  superior  maxillary 
Qerve.  —  lEllis's  VemonstraUons  ;  see  note,  p.  8.31.)] 


«36 


NEUROLOGY. 


the  triangularis  oris,  and  are  entirely  lost  either  in  the  skin  or  in  the  mucous  membrane 
It  is  doubtful  whether  the  buccal  nerve  partially  terminates  in  the  orbicularis  oris,  the 
triangularis  oris,  and  the  zygomaticus  major.  AH  the  filaments  which  enter  these  mus- 
cles, and  which  appear  at  first  sight  to  terminate  in  their  substance,  pass  through  them 
to  supply  the  mucous  membrane  ;  their  branches  anastomose  with  the  mental  nerve  be- 
neath the  triangularis  oris ;  several  filaments  are  lost  in  the  buccinator. 

The  Internal  Pterygoid  Nerve. 
The  internal  collateral  branch  (<,  fig-  299),  or  nerve  for  the  internal  pterygoid  muscle, 
which  is  very  slender,  comes  off  from  the  inner  side  of  the  inferior  maxillary  nerve  in 
contact  with  a  grayish  body,  named  the  otic  ganglion,  runs  downward  and  inward  along 
the  inner  surface  of  the  internal  pterygoid  muscle,  and  ramifies  in  it. 

The  Auricula-temporal  Nerve. 

The  posterior  collateral  branch,  or  the  auricula-temporal  nerve  (the  auricular  or  superfi- 
cial temporal  nerve  of  authors),  is  very  large,  flattened,  and  plexiform  at  its  origin  (be- 
hind c,  fig.  298  ;  r,  fig.  299) ;  it  sometimes  arises  by  a  great  number  of  distinct  roots  ;  it 
passes  backward  and  a  little  downward  behind  the  neck  of  the  condyle  of  the  lower  jaw, 
and  divides  into  two  branches,  a  superior  or  ascending,  and  an  inferior  or  descending  branch. 

The  superior  or  ascending  branch,  the  superficial  temporal  nerve,  turns  round  the  back 
of  the  neck  of  the  condyle,  and  ascends  vertically  between  the  articulation  and  the  ex- 
ternal auditory  meatus  ;  having  become  sub-cutaneous,  it  divides  into  several  filaments 
(r,  fig  285),  which  may  be  traced  up  to  the  highest  part  of  the  temporal  fassa. 

During  its  course  this  nerve  gives  off  a  very  remarkable  anastomotic  branch,  which 
arises  behind  the  neck  of  the  condyle,  and  is  reflected  upon  it  so  as  to  run  forward  be- 
neath the  facial  nerve,  with  which  it  is  blended  opposite  to  the  posterior  border  of  the 
masseter.  This  anastomotic  branch  is  sometimes  double.  It  may  be  regarded  as  one 
of  the  origins  of  the  facial  nerve,  which  increases  considerably  in  size  after  having  re- 
ceived it. 

This  branch  is  one  of  the  principal  communications  between  the  facial  nerve  and  the 
fifth  nerve,  and  modern  physiologists  have  justly  attached  great  importance  to  it. 

The  ascending  branch  also  gives  off  some  plexiform  branches  to  the  temporo-max- 
illary  articulation,  and  several  filaments  to  the  auditory  meatus  and  the  auricle.  In  the 
temporal  region  it  anastomoses  with  a  very  small  filament,  which  is  derived  from  the 
deep  temporal  nerve,  and  which  perforates  the  temporal  fascia.* 

It  accompanies  the  temporal  artery,  for  which  it  forms  a  sort  of  plexus,  and  then  di- 
vides into  cutaneous  filaments,  which  reach  the  crown  of  the  head. 

The  inferior,  descending,  or  auricular  branch  is  as  large  as  the  preceding ;  it  forms  a 
plexus  around  the  internal  maxillary  artery,  behind  the  condyle,  and  sometimes  presents 
small  ganglia  ;  it  divides  into  several  branches,  some  of  which  pass  through  the  parotid 
gland  and  are  distributed  to  the  lobe  of  the  ear,  while  the  others  anastomose  with  some 
filaments  of  the  auricularis  magnus  nerve  derived  from  the  cervical  plexus.  One  of 
these  branches  joins  the  dental  nerve,  before  that  nerve  enters  the  dental  canal ;  an- 
other branch  terminates  in  the  temporo-  maxillary  articulation. 

The  Terminal  Branches  of  the  Inferior  Maxillary  Nerve. 
The  Lingual  Nerve. 
The  lingual  or  gustatory  nerve  {n,figs.  298,  300;  n  n',fig.  301)  passes  downward  and 
Fig.  300.  forward  :  it  is  at  first  situated  between  the  exter- 

nal pterygoid  muscle  and  the  pharynx,  but  it  soon 
passes  between  the  two  pterygoids  {fig.  300),  then 
between  the  internal  pterygoid  and  the  ramus  of 
the  lower  jaw  {fig.  298),  and  then  runs  forward 
along  the  upper  border  of  the  sub-maxillary  gland, 
between  it  and  the  buccal  mucous  membrane,  and 
above  the  mylo-hyoid  muscle ;  it  then  passes  be- 
neath the  sub-lingual  gland,  which  it  crosses,  to 
pass  to  its  inner  side,  and,  accompanied  by  the 
Warthonian  duct,  which  lies  to  its  inner  side  and 
crosses  it  at  a  very  acute  angle,  it  gains  the  corre- 
sponding border  of  the  tongue,  and  ramifies  in  the 
substance  of  that  organ. 

During  its  passage  between  the  two  pterygoids 
the  lingual  nerve  is  joined  by  that  branch  of  the  fa- 
cial nerve  which  is  known  as  the  chorda  tympani  {x, 
fig.  298),  and  which  unites  to  it  behind,  forming  a 
very  acute  angle  opening  upward ;  this  branch  of  the 
facial,  which  may  be  regarded  as  one  of  the  roots 

*  tThis  perforating  cutaneous  fUament  is  one  of  the  temporal  filaments  of  the  orbital  branch  of  the  superior 
maxillary  nerve  (see  notes,  p.  831,  835J.1 


THE  INFERIOR  DENTAL  NERVE,  ETC.  837 

of  the  lingual,  remains  in  contact  with  that  nerve  for  some  time,  and  is  at  last  blended 
with  it. 

The  lingual  nerve  also  receives,  sometimes  before,  and  sometimes  after  being  joined 
by  the  chorda  tympani,  a  very  considerable  anastomotic  branch  from  the  inferior  dental : 
this  branch  is  rarely  wanting. 

After  receiving  these  two  branches,  the  lingual  nerve  becomes  considerably  increased 
in  size,  and  during  its  course  gives  off  several  filaments  to  the  tonsils,  the  mucous  mem- 
brane of  the  cheeks  and  the  gums. 

Opposite  the  sub-maxillary  gland,  the  lingual  nerve  presents  a  very  remarkable  gan- 
glion, generally  described  as  the  sub-maxillary  ganglion  {aitVLdtei  behind  X,  fig.  300);  the 
trunk  of  the  nerve  does  not  enter  into  its  formation,  but  it  appears  to  be  formed  only  by 
its  inferior  filaments.  It  has  been  gratuitously  supposed  that  this  ganglion  is  formed 
exclusively  by  the  chorda  tympani,  which,  according  to  such  a  view,  after  running  in 
mere  contact  with  the  lingual  nerve,  becomes  detached  from  it  (opposite  n)  to  enter  the 
ganglion  (x) :  we  have  stated  that  there  was  equally  little  reason  to  suppose  that  the 
chorda  tympani  was  the  continuation  of  the  cranial  branch  of  the  vidian.  The  sub-max- 
illary ganglion,  the  size  of  which  is  very  variable,  gives  off  a  great  number  of  filaments, 
most  of  which  are  distributed  to  the  sub-maxillary  gland ;  one  of  these  filaments  accom- 
panies the  Warthonian  duct. 

Having  reached  the  sub-lingual  gland,  the  lingual  nerve  supplies  that  gland  with  a 
great  number  of  filaments,  which  dip  into  it  and  form  a  plexus  of  very  delicate  meshes. 

In  the  tongue,  the  lingual  nerve  is  situated  at  the  lateral  border  of  that  organ,  and  on 
a  plane  above  that  of  the  hypoglossal  nerve,  with  which  it  communicates  by  an  anasto- 
motic branch,  forming  a  loop.  It  becomes  gradually  diminished  in  size  by  giving  off  a 
very  numerous  series  of  filaments  {n',fig.  301),  which  turn  round  the  border  of  the  tongue, 
pass  forward  and  upward,  perforate  the  muscles  of  that  organ,  and  spread  out  into  pen- 
cils, the  filaments  of  which  may  be  traced  into  the  papillae  of  the  mucous  membrane. 
The  nerve,  reduced  to  a  single  filament,  terminates  at  the  point  of  the  tongue 

The  Inferior  Dental  Nerve. 

The  inferior  dental  nerve  {m,fig.  298),  larger*  than  the  lingual,  descends  with  it,  at  first 
between  the  two  pterygoid  muscles,  and  then  between  the  internal  pterygoid  and  the  ra- 
mus of  the  lower  jaw  :  in  this  situation  it  is  kept  in  contact  with  the  bone  by  a  layer  of 
fibrous  tissue,  which  is  improperly  called  the  internal  ligament  of  the  temporo-maxillary 
articulation,  and  which  separates  the  nerve  from  the  lingual  nerve  and  the  internal  pter- 
ygoid muscle ;  it  soon  enters  the  dental  canal,  which  it  traverses  (m)  throughout  its 
entire  extent,  accompanied  by  the  inferior  dental  artery,  and  protected  by  a  fibrous  ca- 
nal ;  during  its  course  it  supplies  the  molar  and  the  bicuspid  teeth,  giving  a  twig  to  each 
prong,  and  having  reached  the  mental  foramen,  divides  into  a  mental  and  an  incisor  branch. 

The  Myloid  Branch. — As  it  enters  the  inferior  dental  canal,  the  nerve  gives  off  a  small 
branch,  the  myloid  branch  {z,  fig.  300),  which  arises  from  its  posterior  border,  opposite 
the  corresponding  artery,  is  received  into  a  furrow  upon  the  inner  surface  of  the  ramus 
of  the  jaw,  against  which  it  is  retained  by  a  layer  of  fibrous  tissue,  and  then,  emerging 
from  this  furrow,  passes  upon  the  upper  surface  of  the  mylo-hyoid  muscle,  in  which  it 
ramifies.  A  great  number  of  filaments  from  the  myloid  nerve  enter  the  anterior  belly  of 
the  digastric  muscle. t 

The  mental  branch  {t,fig.  285),  the  continuation  of  the  inferior  dental  nerve,  as  far  as 
size  is  concerned,  passes  through  the  mental  foramen,  and  expands  into  diverging  fila- 
ments, which  are  distributed,  in  reference  to  the  lower  lip,  in  the  same  way  as  the  infra- 
orbital branch  is  to  the  upper  lip.  These  filaments  interlace  with  the  facial  nerve,  and 
form  with  it  a  sort  of  mental  plexus ;  they  are  intended  for  the  skin  and  the  mucous 
membrane  of  the  lower  lip  :  most  of  them  pass  to  the  free  border  of  that  lip. 

The  inrisor  dental  branch,  which  is  extremely  small,  continues  in  the  original  course 
of  the  inferior  dental  nerve,  and  subdivides  to  supply  the  canine  and  two  corresponding 
incisor  teeth. 

The  inferior  dental  nerve  represents  in  the  lower  jaw  the  infra-orbital  portion  of  the 
superior  maxillary  nerve  in  the  upper  jaw. 

The  Otic  Ganglion. 

I  cannot  terminate  the  description  of  the  inferior  maxillary  nerve  without  noticing  a 
ganglion  recently  described  by  Arnold,  under  the  name  of  the  olic  ganglion,  which  he 
compares  to  the  ophthalmic  ganglion,  and  which  has  served  him  as  the  basis  of  an  inge- 
nious theory  respecting  the  nerves  of  the  head.  The  following  is  the  position  of  the 
ganglion,  as  indicated  by  Arnold  :  "The  otic  ganglion  is  situated  (behind  I, fig.  299)  im- 
mediately below  the  foramen  ovale,  on  the  inner  side  of  the  third  or  inferior  maxillary 

*  I  have  observed  that  thi.s  nerve  was  much  smaller  in  old  than  in  young-  subjects. 

t  [Filaments  are  also  given  to  the  sub-maxillary  gland  ;  according  to  Ellis,  some  branches  pass  through 
the  mylo-hyoid  muscle  and  enter  the  genio-hyoid ;  and  it  is  stated  bv  Alcock  that  a  branch  reaches  the  de- 
pzecsor  labii  inferioris.] 


888  NEUROLOGY. 

division  (c)  of  the  fifth  nerve,  a  little  above  the  origin  of  the  superficial  temporal  or  au- 
ricular nerve  (auriculo-temporal),  at  the  spot  where  the  inferior  maxillary  nerve  gives  off 
from  its  external  surface  the  deep  temporal  and  buccal  nerves,  and  where  the  small  root 
of  the  fifth  unites  intimately  with  the  large  root.  On  the  inner  side,  this  ganglion  is 
covered  by  the  cartilaginous  portion  of  the  Eustachian  tube,  and  by  the  origin  of  the  ex- 
ternal peristaphyline  {circumflexus  palati)  muscle  ;  behind,  it  is  in  contact  with  the  mid- 
dle meningeal  artery.  Its  external  surface  rests  upon  the  inner  side  of  the  inferior  max- 
illary nerve." 

There  can  be  no  doubt  that  in  the  situation  indicated  by  Arnold,  there  is  a  thin  and 
not  very  well-defined  layer  of  reddish,  pulpy  tissue,  placed  upon  the  inner  side  of  the  in- 
ternal pterygoid  nerve,  and  which  presents  the  chief  characters  of  ganglionic  tissue  ;  for 
it  is  traversed  by  nervous  filaments,  which  proceed  from  it  as  from  a  centre,  and  run  in 
various  directions. 

Its  connexions  with  the  inferior  maxillary  nerve  are  effected  by  its  direct  adhesion  to 
that  nerve,  which  adhesion,  according  to  Arnold,  takes  place  by  means  of  several  very 
short,  nervous  filaments  {short  root),  which  appear  to  come  from  the  small  root  of  the  fifth 
pair,  and  also  by  its  adhesion  to  the  internal  pterygoid  nerve  ;  so  that,  at  first  sight,  the 
ganglion  would  appear  to  originate  from  that  nerve,  or  the  nerve  from  the  ganglion. 

The  otic  ganglion  is  also  connected  with  the  glosso-pharyngeal  by  means  of  a  filament, 
which  Arnold  describes  under  the  name  of  the  small  superficial  petrosal  nerve,  to  distin- 
guish it  from  the  great  superficial  petrosal,  or  cranial  branch  of  the  vidian.  This  fila- 
ment, which  proceeds  from  the  nerve  of  Jacobson,  or  tympanic  branch  of  the  glosso-pha- 
ryngeal, is  compared  by  Arnold  to  the  Imig  root  of  the  ophthalmic  ganglion :  it  passes 
out  of  the  cavity  of  the  tympanum  by  a  special  canal,  in  front  of  the  hiatus  Fallopii,  runs 
forward  and  outward  (from  7  towards  c,  fig.  296),  emerges  from  the  cranium  through  a 
special  foramen,  between  the  petrous  portion  of  the  temporal  bone  and  the  spinous  pro- 
cess of  the  sphenoid,  and  proceeds  (above  I,  Jig.  300)  to  enter  the  otic  ganglion.*  Ar- 
nold admits  a  third  root  for  the  otic  ganglion,  namely,  a  soft  root,  which  he  traces  from 
the  nervous  plexus  that  surrounds  the  middle  meningeal  artery,  and  is  derived  from  the 
great  sympathetic. 

The  preceding  filaments  may  be  regarded  as  the  filaments  of  origin  of  the  otic  gan- 
glion.t 

The  Branches  which  proceed  from  the  Otic  Ganglion. — The  principal  filament  from  the 
otic  ganglion  runs  backward  and  upward  towards  the  canal  which  contains  the  internal 
muscle  of  the  malleus,  and  is  lost  in  that  muscle.  This  twig  must  be  carefully  distin- 
guished from  the  small  superficial  petrosal  nerve,  which  is  placed  above  it.  Some  other 
filaments  join  the  auriculo-temporal  nerve,  which  generally  arises  by  two  roots. 

Lastly,  the  otic  ganglion  sends  off  a  twig  to  the  circumflexus  palati  muscle. 

The  Sixth  Pair,  or  External  Motor  Nerves  of  the  Eyes. 

The  very  simple  distribution  of  the  external  motor  nerve  of  the  eye,  or  sixth  crania} 
nerve,  contrasts  strongly  with  that  of  the  fifth  nerve  ;  it  arises  from  the  furrow  between 
the  pons  Varolii  and  the  medulla  oblongata,  immediately  forms  two  fasciculi  or  roots,  a 
large  and  a  small,  which  unite  in  the  cavernous  sinus  ;  they  pass  vertically  upward,  per- 
forate the  dura  mater  {b,  fig.  296)  at  the  side  of  the  basilar  groove  by  one  or  two  open- 
ings, to  the  inner  side  of  and  below  the  fifth  nerve,  gain  the  apex  of  the  petrous  portion 
of  the  temporal  bone,  over  which  they  turn,  and  then  pass  horizontally  forward  to  enter 
the  cavernous  sinus.  During  the  course  of  the  nerve  through  that  sinus,  it  rests  upon 
its  lower  wall,  crosses  (above  6,  fig.  301)  on  the  outer  side  of  the  vertical  portion  of  the 
internal  carotid  artery,  around  which  it  turns,  and  then  runs  along  its  horizontal  portion. 
The  sixth  nerve  forms  a  most  important  anastomosis,  on  account  of  which  it  was  for  a 
long  time  regarded  as  the  origin  of  the  great  sympathetic.  As  it  crosses  the  internal 
carotid  in  the  cavernous  sinus,  it  communicates  by  one  or  two  filaments  with  the  supe- 
rior cervical  ganglion.  It  also  communicates,  at  the  same  point,  with  the  ophthalmic 
division  of  the  fifth  nerve. 

Lastly,  it  enters  the  orbit  through  the  widest  part  of  the  sphenoidal  fissure,  passes 
through  the  fibrous  ring  which  is  common  to  it  and  to  the  inferior  division  of  the  com- 
mon motor  nerve,  crosses,  at  an  acute  angle,  beneath  the  ophthalmic  nerve,  and  gains 
the  inner  surface  of  the  external  rectus,  and  penetrates  that  muscle,  after  having  ex- 
panded into  a  pencil  of  very  delicate  filaments. 

We  shall  again  advert  to  the  communication  between  this  nerve  and  the  superior  cer-'» 
vical  ganglion. 

*  This  small  superficial  petrosal  nerve  is  very  distinct  from  the  great  superficial  petrosal  nerve,  being  situ 
ated  in  front  of  and  parallel  to  that  nerve.  In  a  subject  which  I  dissected  in  J826,  I  found  this  small  nerve 
presenting  the  following  peculiarity  :  it  had  a  well-marked  nodule  or  ganglion,  which  gave  off  a  filament  to 
the  middle  meningeal  artery,  and  some  small  twigs,  which  appeared  to  me  to  be  lost  in  the  substance  of  the 
sphenoid  bone  ;  but  I  did  not  discover  the  connexions  of  this  nerve. 

t  Arnold  admits  an  indirect  communication  between  the  otic  gan!>;lion  and  the  acoustic  nerve  through  the 
intervention  of  the  facial  nerve.  The  existence  of  this  communication  appears  to  me  very  doubtful,  as  well 
as  the  communication  of  the  otic  ganglion  with  the  great  sympathetic,  by  means  of  the  twigs  on  the  middle 
meningeal  artery 


THE    FACIAL    NERVE.  839 

The  Seventh  Pair  of  Nerves 
The  Portio  Dura,  or  the  Facial  JVerve. 

We  have  already  traced  the  facial  nerve,  or  the  portio  dura  of  the  seventh,  from  its  on 
gin  to  the  internal  auditory  meatus,  which  it  enters  together  with  the  auditory  nerve  (7, 
Jig.  296),  which  nerve  lies  below  and  behind  the  facial,  and  forms  a  groove  for  its  recep- 
tion. Having  reached  the  bottom  of  the  internal  auditory  meatus,  this  nerve  follows  the 
long  course  of  the  facial  canal,*  or  aqueduct  of  Fallopius,  a  winding  passage  which  is 
formed  in  the  petrous  portion  of  the  temporal  bone,  and  which  opens  by  one  end  into  the 
internal  auditory  meatus,  and,  by  the  other,  upon  the  lower  surface  of  the  pars  petrosa 
at  the  stylo-mastoid  foramen. 

The  facial  nerve  traverses  this  canal,  which  is  exclusively  appropriated  to  it ;  it  is  at 
first  directed  outward  (n,  fig.  296),  and,  after  proceeding  for  about  a  line,  bends  sudden- 
ly, and  runs  backward,  in  the  substance  of  the  internal  wall  of  the  cavity  of  the  tympa- 
num, above  the  fenestra  ovalis.  Having  reached  the  back  of  the  tympanum,  it  forms 
another  bend,  and  passes  vertically  downward  (o,  figs.  298,  300)  to  the  stylo-mastoid  fo- 
ramen. It  follows,  therefore,  that  the  facial  nerve  describes  two  curves,  like  the  aque- 
duct of  Fallopius,  and  is  horizontal  in  its  first  two  portions  and  vertical  in  the  third. 

On  emerging  from  the  stylo-mastoid  foramen,  the  facial  nerve  runs  forward  in  the 
substance  of  the  parotid  gland,  and,  after  a  course  of  about  five  or  six  hues,  divides  into 
two  terminal  branches,  the  temporo-facial  (g,  fig.  285)  and  the  cervico-facial  (/),  which 
expand  into  a  great  number  of  diverging  filaments,  and  cover  the  temples,  the  whole  of 
the  face,  and  the  upper  part  of  the  neck,  with  their  radiations  and  anastomoses. 

The  facial  nerve  gives  off  and  receives  certain  collateral  branches  before  and  others 
after  its  exit  from  the  stylo-mastoid  foramen. 

The  Collateral  Branches  of  the  Facial  Nerve,  before  its  Exit  from  the  Stylo-mastoid  Foramen. 

In  the  internal  auditory  meatus  the  facial  nerve  receives  some  twigs  from  the  auditory, 
a  remarkable  anastomosis,  which  deserves  the  attention  of  physiologists. 

Opposite  to  the  hiatus  Fallopii,  i.  e.,  at  the  first  bend  formed  by  the  Fallopian  aque- 
duct, the  facial  nerve  is  joined  by  the  cranial  branch  of  the  vidian,  or  the  great  super- 
ficial petrosal  nerve  (c>  figs.  296,  300).  According  to  MM.  Ribes,  Hippolyte  Cloquet, 
and  Hirzel,  this  branch  is  applied  to  the  facial  nerve,  but  does  not  anastomose  with  it, 
and  is  detached  from  it  lower  down  to  constitute  the  chorda  tympani  nerve  ;  and  as  the 
cranial  branch  of  the  vidian  arises  from  the  spheno-palatine  ganglion,  and  the  chorda 
tympani  is  supposed  to  enter  the  sub-maxillary  ganglion,  it  is  seen  that,  according  to 
this  view,  the  cranial  branch  of  the  vidian  and  the  chorda  tympani,  which  is  regarded 
as  its  prolongation,  would  establish  a  communication  between  the  spheno-palatine  and 
sub-maxillary  ganglia.  It  is  by  no  means  proved,  however,  that  the  chorda  tympani  en- 
ters the  sub-maxiUary  ganglion ;  and,  again,  the  supposed  connexion  between  the  cra- 
nial branch  of  the  vidian  and  the  chorda  tympani  is  opposed  to  facts.  The  cranial 
branch  of  the  vidian  and  the  facial  nerves,  indeed,  are  not  in  mere  juxtaposition,  but 
anastomose  and  are  blended  with  each  other,  and  the  chorda  tympani  has  no  sort  of  re- 
lation to  the  former  of  these  nerves.  This  independence  of  the  branch  of  the  vidian 
nerve  and  the  chorda  tympani  can  be  most  clearly  seen  when  the  parts  have  been  ma- 
cerated in  diluted  nitric  acid.t 

If  an  explanation  must  be  given  of  this  remarkable  anastomosis  between  the  vidian 
and  facial  nerves,  I  would  say  that  the  cranial  branch  of  the  vidian  may  be  regarded  as 
a  remote  origin  or  a  re-enforcing  branch  of  the  facial  nerve. 

The  facial  nerve,  according  to  Soemmering  and  those  who  have  followed  him,  gives 
off  a  twig  to  the  internal  muscle  of  the  malleus,  and  another  to  the  small  muscle  of  the 
stapes ;  but,  in  the  first  place,  the  existence  of  a  stapedius  muscle  is  doubtful,  and,  con- 
sequently, the  existence  of  a  corresponding  nervous  twig  must  also  be  so,  and,  in  the 
second  place,  the  internal  muscle  of  the  malleus  is  not  supplied  from  the  facial  nerve, 
but  from  the  inferior  maxillary  division  of  the  fifth  nerve,  and  more  especially  from  that 
pulpy,  reddish  tissue,  named  by  Arnold  the  otic  ganglion. 

Before  leaving  the  aqueduct  of  Fallopius,  the  facial  nerve  (n,fig.  296)  gives  a  remark- 
able filament,  named  the  chorda  tympa7ii,  which  pursues  a  recurrent  course  (y)  from  be- 
low upward  in  a  peculiar  canal,  parallel  to  the  aqueduct  of  Fallopius,  enters  the  cavity 
of  the  tympanum  through  an  opening  to  the  inner  side  of  and  behind  the  attachment  of 
the  membrana  tympani,  passes  downward  and  forward  through  the  cavity  of  the  tym- 

*  For  what  purpose  is  this  long-  course  within  the  petrous  portion  of  the  temporal  bone  ?  Those  physiolo- 
gists who  believe  the  facial  nerve  to  be  of  a  mixed  nature,  that  is,  both  sensory  and  motor,  have  laid  great 
stress  upon  this  point,  which  they  conceive  to  be  favourable  to  their  views ;  but  there  is  not  the  slightest 
shadow  of  a  proof  that  the  facial  nene  possesses  these  two  properties. 

t  Arnold  has  pointed  out,  at  the  junction  of  the  cranial  branch  of  the  vidian  with  the  facial  nerve,  a  gangli- 
form  swelling,  which  he  regards  as  a  transition  between  a  gangliform  enlargement  and  a  true  ganglion  ;  from 
this  swelling,  which  he  compares  to  the  ganglia  of  the  posterior  roots  of  the  spinal  nerves,  he  says  a  filament 
is  given  off  to  anastomose  with  the  auditory  nerve  at  the  bottom  of  the  internal  .auditory  meatus.  I  have  not 
been  fortunate  enough  to  discover  this  filament ;  nor  have  I  ever  seen  any  gangliform  appearance  at  the  junc- 
tion of  the  vidian  and  facial  nerves. 


840  NEUKOLOGY. 

panum,  between  the  handle  of  the  malleus  and  the  vertical  ramus  of  the  incus,  and 
emerging  from  that  cavity  {x,fig.  298),  not  through  the  Glasserian  fissure,  but  through  a 
special  opening  already  described  (see  Organ  of  Hearing — Cavity  of  the  Tympanum),  is 
applied  to  the  lingual  nerve  («),  of  which  it  may  be  regarded  as  a  late  origin,  or  re-enfor- 
cing branch. 

The  facial  branch  also  receives,  in  the  aqueduct  of  Fallopius,  opposite  to  where  it  gives 
off  the  chorda  tympani,  a  very  remarkable  branch  from  the  pneumogastric  nerve,  which 
Arnold  has  named  the  auricular  branch  of  the  pneumogastric. 

The  Collateral  Branches  of  the  Facial  Nerve,  after  its  Exit  from  the  Stylo-mastoid  Foramen. 

Before  its  terminal  division,  the  facial  nerve  gives  off  two  branches,  the  posterior 
auricular  and  the  styloid.     I  have  never  seen  any  parotid  branch,  properly  so  called. 

The  posterior  auricular,  which  would  be  better  named  the  auriculo-occipital,  comes  ofl 
from  the  nerve  within  the  stylo-mastoid  foramen,  and  is  immediately  applied  against  the 
mastoid  process,  turning  round  over  its  anterior  and  then  its  outer  surface  ;*  as  it  lies  in 
front  of  the  mastoid  process,  it  anastomoses  with  a  remarkable  twig  from  the  deep  auric- 
ular branch  of  the  auricularis  magnus  from  the  cervical  plexus  ;t  after  this,  it  divides 
into  two  branches  :  an  ascending  or  auricular  branch  {m,  fig.  299),  properly  so  called, 
which,  having  first  supplied,  then  perforates  the  posterior  auricular  muscle,  turns  round 
the  auricle,  and  terminates  in  the  superior  auricular  muscle  ;  and  a  horizontal  or  occipital 
branch  («,  fig.  285),  which  is  larger,  and  forms  the  continuation  of  the  nerve  ;  it  passes 
immediately  beneath  the  posterior  auricular  muscle,  to  which  it  gives  some  filaments, 
then  runs  exactly  along  the  superior  semicircular  line  of  the  occipital  bone,  and  termi- 
nates by  giving  off  from  its  upper  side  a  series  of  small  filaments,  which  are  lost  in  the 
occipital  portion  of  the  occipito-frontalis  :  they  can  be  traced  as  far  as  the  median  line, 
but  none  of  them  are  distributed  to  the  skin. 

The  styloid  branch  arises  from  the  back  of  the  facial  nerve,  at  its  exit  from  the  stylo- 
mastoid foramen,  and  enters  the  stylo-hyoid  muscle,  after  having  run  along  its  upper 
border. 

The  posterior  mastoid  or  digastric  branch  often  arises  by  a  common  trunk  with  the  pre- 
ceding, enters  the  posterior  belly  of  the  digastric  muscle,  and  sends  off  an  anastomotic 
twig  to  the  glosso-pharyngeal  nerve. 

The  Terminal  Branches  of  the  Facial  Nerve. 

The  Temporo-facial  Nerve. 

The  temporo-facial  nerve  {g,  fig.  285)  passes  upward  and  forward  in  the  substance  of 
the  parotid,  forming,  with  the  trunk  of  the  facial  nerve,  an  arch  having  its  concavity 
turned  upward  ;  it  crosses  the  neck  of  the  condyle  of  the  lower  jaw,  and  receives  in  this 
situation,  by  its  deep  surface,  one,  or  sometimes  two  branches  from  the  auriculo-tempo- 
ral  nerve,  a  branch  of  the  inferior  maxillary.  This  anastomotic  branch  establishes  a 
very  important  connexion  between  the  fifth  and  facial  nerves. 

The  temporo-facial  nerve,  which  is  flattened  and  plexiform  where  it  is  joined  by  the 
branch  from  the  fifth,  afterward  expands  into  a  number  of  filaments,  which  anastomose 
with  each  other,  so  as  to  form  arches,  from  the  convexity  of  which  a  number  of  diverging 
filaments  of  unequal  size  proceed  like  rays,  and  cover  the  whole  space  comprised  be- 
tween a  vertical  line  drawn  in  front  of  the  ear,  and  a  horizontal  line  corresponding  to  the 
base  of  the  nose. 

All  these  branches,  which  anastomose  several  times  with  each  other,  and  form  a  suc- 
cession of  arches  somewhat  resembling  those  of  the  mesenteric  arteries,  may  be  divided 
into  the  temporal,  the  orbital,  and  the  infra-orbital  or  buccal  branches. 

The  temporal  branches  ascend,  cross  over  the  zygomatic  arch  at  right  angles,  and  cov- 
er with  their  ramifications  the  whole  of  the  temporal  and  frontal  regions,  anastomosing 
with  filaments  from  the  frontal  branch  of  the  first  [from  the  orbital  branch  of  the  second], 
and  from  the  auriculo-temporal  branch  of  the  third  division  of  the  fifth  nerve. 

All  these  branches  lie  between  the  skin  and  the  temporal  aponeuroses  ;  some  of  them 
supply  the  skin,  but*  the  majority  are  distributed  to  the  frontal  portion  of  the  occipito- 
frontalis  muscle,  below  which  they  are  situated,  and  may  be  traced  as  far  as  the  median 
line. 

The  orbital  branches  may  be  divided  into  the  superior  palpebral,  which  are  remarkably 
long,  and  pass  beneath  the  orbicularis  palpebrarum,  to  ramify  in  that  muscle  and  the 
corrugator  supercilii.  Several  of  these  anastomose  with  twigs  from  the  supra-orbital 
nerve  :  the  middle  palpebral  branches.  Which  gain  the  outer  angle  of  the  eyelids,  and  are 
distributed  between  the  upper  and  lower  eyelids,  and  the  superior  palpebral  branches, 
which  are  generally  named  the  malar  branches  ;  they  pass  horizontally  forward,  opposite 
to  the  lower  part  of  the  orbicularis  palpebrarum,  and  are  reflected  upward,  to  enter  the 

*  This  little  nerve  is  lodged  in  the  furrow  between  the  mastoid  and  vaginal  processes  (see  Osteology, 
p.  43). 

t  [It  is  also  joined,  according  to  Arnold,  by  a  filament  from  the  auricular  branch  of  the  pneumogastric  (sea 
note,  p.  844). 


THK    CERVICO- FACIAL    NERVE.  841 

substance  of  the  lower  eyelid,  between  the  palpebral  aponeurosis  and  the  palpebral  por- 
tion of  the  orbicularis,  in  which  they  terminate. 

They  may  be  traced  as  far  as  the  free  border  of  the  tarsal  cartilage,  where  they  anas- 
tomose with  each  other. 

The  infra-orbital  or  buccal  branches  of  the  temporo-facial  are  given  off  from  one  or  two 
large  branches  which  accompany  the  Stenonian  duct ;  they  expand  into  a  great  number 
of  filanients,  which  may  be  divided  into  a  superficial  and  a  deep  set :  the  superficial  branch- 
es ran  beneath  the  skin,  and  above  the  orbicularis  oris,  the  two  zygomatic,  and  the  le- 
vator labii  superioris,  all  of  which  they  supply ;  there  can  be  no  doubt  that  they  also 
give  cutaneous  filaments  ;  these  are  very  small,  and  very  long,  and  may  be  followed  as 
far  as  the  hair  follicles  in  the  upper  lip  ;  some  of  these  superficial  branches  reach  the 
lower  eyelid,  several  accompany  the  facial  and  angular  veins,  anastomose  with  twigs 
from  the  infra-trochlear  branch  of  the  nasal  nerve,  and  ascend  as  far  as  the  pyramidalis 
nasi,  in  which  they  terminate. 

The  deep  branches  pass  beneath  the  levator  labii  superioris,  send  off  numerous  fila- 
ments to  that  and  the  levator  anguli  oris,  and  form,  together  with  the  terminal  divisions 
of  the  infra-orbital  branch  of  the  superior  maxillary,  a  very  remarkable  plexus,  which 
may  be  called  the  infra-orbital. 

This  plexus  is  formed  by  the  interlacement  of  the  radiating  branches  of  the  facial 
nerve  with  those  of  the  infra-orbital  branch  of  the  superior  maxillary  division  of  the  fifth 
nerve.  Now,  as  the  facial  nerve  radiates  from  without  inward,  and  the  infra-orbital 
from  above  downward,  it  follows  that  the  branches  of  these  two  nerves  meet  each  other 
at  right  angles.  This  arrangement  can  be  rendered  more  evident  by  pulling  the  two 
sets  of  nerves  in  the  direction  of  their  length.  Most  of  these  branches  interlace  with- 
out anastomosing,  and  proceed  directly  to  their  destination.  The  destination  of  the 
facial  nerve  is  evidently  rather  to  the  muscles  than  to  the  skin ;  that  of  the  infra-orbital 
branch  of  the  fifth  nerve  is  rather  to  the  skin  and  mucous  membrane  than  to  the  mus- 
cles ;  nevertheless,  it  cannot  be  doubted  that  the  facial  nerve  supplies  some  cutaneous 
filaments,  and  that  the  fifth  nerve  gives  some  twigs  to  the  muscles.  Besides,  there  are 
some  undoubted  anastomoses  between  these  two  nerves.  The  facial  also  communicates 
very  freely  with  the  buccal  nerve,  a  branch  of  the  inferior  maxillary. 

The  infra-orbital  branches  of  the  temporo-facial  nerve  supply  the  two  zygomatics,  the 
levator  labii  superioris,  the  levator  labii  superioris  alaeque  nasi,  the  depressor  alae  nasi, 
the  transversalis  nasi,  the  levator  anguli  oris,  and  the  orbicularis  oris.  I  would  also 
point  out  a  very  remarkable  branch,  which  enters  the  substance  of  the  ala  of  the  nose, 
and  appears  to  be  intended  for  that  sort  of  sphincter  muscle  found  in  the  cutaneous  fold 
of  the  alae.  This  branch  anastomoses  with  the  naso-lobar  branch  of  the  internal  nasal 
nerve. 

The  infra-orbital  branches  of  the  fifth  nerve  are  distinguished  from  the  infra-orbital 
branches  of  the  facial  nerve,  by  their  direction  ;  by  being  more  deeply  seated  ;  by  being 
much  larger ;  and  by  being  arranged  in  successive  layers,  which  are  three  in  number  : 
a  sub-cutaneous,  a  sub-mucous,  and  a  muscular ;  this  last  set  perforates  the  orbicularis 
oris,  in  which  some  filaments  appear  to  terminate.  Among  the  infra-orbital  branches 
of  the  fifth  nerve,  there  is  one  which  may  be  called  the  nerve  of  the  sub-septum,  which 
runs  on  the  side  of  the  median  line,  as  far  as  the  tip  of  the  nose,  where  it  terminates. 
Lastly,  the  infra-orbital  branches  of  the  fifth  give  a  dorsal  branch  for  the  nose,  and  two 
ascending  palpebral  branches,  which  can  be  easily  distinguished  from  the  palpebral 
branches  of  the  facial  nerve. 

The  Ccrvico-facial  Nerve. 

The  ccrvico-facial  nerve  (/,  fig.  285),  which  is  smaller  than  the  temporo-facial,  follows 
the  original  course  of  the  facial  nerve,  and,  like  it,  runs  downward  and  forward  in  the 
parotid  gland  ;  opposite  to  the  angle  of  the  lower  jaw  it  divides  into  three  or  four  branch- 
es, which  subdivide  into  secondary  branches,  which  may  be  arranged  into  the  buccal,  men- 
tal, and  cervical  sets. 

The  buccal  branches  run  horizontally  forward  in  front  of  the  masseter,  to  which  they 
give  off"  some  small  filaments,  and  then  anastomose  with  each  other  and  with  the  infra- 
orbital branches  of  the  temporo-facial  nerve.  A  very  beautiful  anastomosis  is  found  be- 
tween the  buccal  branch  of  the  inferior  maxillary  and  one  of  these  buccal  branches  of 
the  cervico-facial  nerve  :  we  have  already  pointed  out  a  similar  anastomosis  between 
an  infra-orbital  branch  of  the  temporo-facial  and  this  same  buccal  branch  of  the  inferior 
maxillary. 

The  mental  branches  are  intended  for  the  lower  lip.  They  are  reflected  upward,  so  as 
to  describe  an  arch  having  its  concavity  directed  upward  ;  they  are  at  first  situated  be- 
neath the  platysma  myoides,  then  pass  beneath  the  triangularis  oris,  and  form,  with  the 
mental  branch  of  the  inferior  maxillary  division  of  the  fifth  nerve,  an  interlacement  or 
mental  plexus,  which  has  a  close  analogy  with  the  interlacement  of  the  infra-orbital 
branches  of  the  facial  with  those  of  the  superior  maxillary  division  of  the  fifth  nerve,  but 
is  less  comnlicated. 

50 


842  NEUROLOGY. 

Thus,  the  mental  branches  of  the  facial  nerve  are  more  superficial  than  those  of  the 
fifth,  and  their  filaments  are  smaller  ;  the  radiating  branches  of  the  facial  nerve  run  at 
first  forward  and  then  upward,  while  those  of  the  fifth  nerve  run  directly  upward.  The 
mental  brandies  of  the  facial  nerve  perforate  the  quadratus  rnenti  and  the  orbicularis 
oris,  to  which  muscles  they  are  almost  entirely  distributed  ;  they  also  send  several  long 
and  slender  filaments  to  the  point  of  the  chin,  some  of  which  are  cutaneous.  The  men- 
tal branches  of  the  fifth  nerve  are  chiefly  situated  between  the  muscles  and  the  mucous 
membrane,  to  w  hich  latter  they  are  distributed,  more  especially  to  the  free  borders  of 
the  lower  lip. 

The  cervical  branches  of  the  cervico-facial  run  forward  in  the  supra-hyoid  region,  be- 
neath the  platysma,  and,  describing  arches  with  their  concavities  turned  upward,  they 
pass  upward  and  forward  to  terminate  near  the  chin.  Among  these  branches,  there  is 
one  which  passes  vertically  downward  to  anastomose  with  the  superficial  cervical  nerve 
of  the  cervical  plexus. 

The  cervical  branches  of  the  facial  nerve  are  separated  from  the  cervical  branches  of 
the  cervical  plexus  by  the  platysma,  and  they  are  all  distributed  to  that  muscle  and  the 
levator  labii  superioris. 

Summary. — The  facial  nerve  supplies  all  the  cutaneous  muscles  of  the  cranium  and 
of  the  face,  and,  therefore,  section  and  compression  of  this  nerve  cause  complete  paral- 
ysis of  these  muscles  :  it  is  the  nerve  of  expression,  or  the  respiratory  nerve  of  the 
face  {Bell) ;  it  also  evidently  gives  off  some  cutaneous  filaments,  especially  near  the 
commissure  of  the  lips,  and  this  may  explain  the  numbness  which  I  have  known  to  oc- 
cur in  individuals  affected  with  hemiplegia  of  the  face  ;  lastly,  it  furnishes  a  great  num- 
ber of  anastomotic  filaments  (whence  it  has  been  called  the  small  sympathetic) ;  these 
are  given  to  the  branches  of  the  cervical  plexus,  to  the  auditoiy  nerve,  to  the  pneumo- 
gastric,  and  more  especially  to  the  fifth  nerve. 

The  anastomoses  of  the  facial  with  the  fifth  nerve  merit  special  notice  ;  they  are  ef- 
fected with  the  frontal  and  nasal  nerves  of  the  ophthalmic  or  first  division  of  the  fifth  ; 
with  the  superior  maxillary  or  second  division  by  means  of  the  infra-orbital  nerves  and 
the  cranial  branch  of  the  vidian,  which  latter  I  even  regard  as  one  of  the  origins  of  the 
facial  nerve  ;  and  with  the  inferior  maxillary  or  third  division  of  the  fifth  by  means  of 
the  mental  nerve,  the  buccal  nerve,  and  more  especially  the  auriculo-temporal  nerve. 
The  branch  given  by  the  auriculo-temporal  to  the  facial  nerve  may  be  regarded  as  one 
of  the  origins  of  the  last-mentioned  nerve. 

Notwithstanding  these  numerous  anastomoses,  the  facial  nerve  and  the  fifth  nerve 
cannot  supply  the  place  of  each  other.  Anatomy  shows  no  difference  in  the  structure 
of  these  nerves,  but  a  great  difference  in  their  distribution  ;  the  facial  nerve  being  in- 
tended for  the  muscles,  while  the  fifth  is  distributed  to  the  integuments  and  the  organs 
of  the  senses. 

Function. — The  facial  is  a  nerve  of  motion.  This  fact  may  be  deduced  from  its  ana- 
tomical description  no  less  than  from  physiological  experiments  and  the  effects  of  disease. 

The  Portio  Mollis,  or  the  Auditory  J^erve. 

The  auditory  nerve  (7,  figs.  296,  301),  which  we  have  already  traced  as  far  as  the  in- 
ternal auditory  meatus,  enters  that  canal  with  the  facial  nerve,  for  which  it  forms  a 
groove,  and  divides  into  two  cords,  which  remain  distinct  throughout  the  whole  extent 
of  the  passage,  but  continue  in  contact  with  each  other,  and  at  length  pass  through  the 
foramina  in  the  cribriform  plate  already  described  as  existing  at  the  bottom  of  the  meatus 
(see  Osteology). 

In  order  to  understand  the  farther  distribution  of  the  auditory  nerve,  the  cribriform 
plate  of  the  auditory  meatus  must  be  examined  with  the  same  attention  as  was  devoted 
by  Scarpa  to  the  cribriform  plate  of  the  ethmoid,  with  which  it  has  so  many  analogies. 
As  the  cribriform  plate  of  the  ethmoid  presents  a  particular  fissure  for  the  passage  of  the 
ethmoidal  branch  of  the  ophthahnic  nerve,  so  the  cribriform  plate  of  the  internal  auditory 
meatus  presents  a  special  opening  for  the  passage  of  the  facial  nerve  ;  and  again,  the 
auditory,  like  the  olfactory  nerve,  seems  as  if  it  were  pressed  through  the  foramina  of 
the  cribriform  plate  to  enter  the  internal  ear. 

Of  the  two  terminal  branches  of  the  auditory  nerve,  the  anterior  is  intended  for  the 
cochlea,  the  posterior  for  the  vestibule  and  semicircular  canals. 

The  cochlear  branch  turns  spirally,  like  that  part  of  the  bottom  of  the  auditory  meatus 
to  which  it  belongs,  and  which  is  called  the  tractus  spiralis.  It  then  turns  upon  itself, 
as  observed  by  Valsalva,  and  presents  somewhat  of  a  ganglionic  appearance.  From  this 
sort  of  enlargement  the  cochlear  filaments  proceed  ;  those  which  belong  to  the  first  turn 
of  the  cochlea  run  along  the  surface  of  the  modiolus  ;  the  others  enter  the  canals  of  the 
modiolus,  and  are  distributed  on  the  second,  and  the  succeeding  half  turn  at  the  summit 
of  the  cochlea.  I  have  already  described  the  very  regular  manner  in  which  these  fila- 
ments spread  upon  the  spiral  septum,  the  subdivision  of  each  of  them  into  two  or  three 
filaments,  which  anastomose  with  each  other  lite  the  ciliary  nerves,  and  the  gradual  dim- 
inution in  the  length  of  these  filaments  from  the  base  to  the  apex  of  the  cochlea ;  so  that, 


THE    GLOSSO-PHARYNGEAL    NERVE. 


it  we  suppose  the  spiral  septum  spread  out,  it  might  be  compared  to  a  harpsichord,  the 
longest  strings  of  which  would  be  represented  by  the  filaments  at  the  base  of  the  trian- 
gle formed  by  the  septum,  and  the  shortest  by  those  at  its  apex  (see  Internal  Eae,  p.  681). 

The  vestibular  branch  divides  into  three  parts,  the  largest  of  which  enters  the  utricle 
and  the  ampullce  of  the  superior  vertical  and  horizontal  membranous  canals,  the  middle, 
sized  branch  passes  to  the  sacculus,  and  the  smallest  branch  to  the  ampulla  of  the  pos- 
terior or  inferior  vertical  semicircular  canal. 

Function. — The  auditory  nerve  is  exclusively  the  nerve  of  hearing. 

The  Eighth  Pair  op  Nerves. 

The  First  Portion,  or  Glosso-Pharyngeal  JVerve. 

Dissection. — Remove,  by  a  triangular  section,  the  posterior  half  of  the  border  of  the 

foramen  lacerum  posterius ;   carefully  detach  the  jugular  vein,  in  front  of  which  the 

nerves  are  situated,  examine  the  connexions  of  the  glosso-pharyngeal  with  the  pneumo- 

gastric  and  spinal  accessory  nerves. 

The  glosso-pharyngeal  nerve  {pharyngo-glossal),  the  anterior  portion  of  the  eighth  nerve 
(8,  Jigs.  296,  301),  the  ninth  nerve  of  some  authors,  is  intended  for  the  pharynx  and  the 
tongue. 

Having  arisen  from  the  restiform  body,  above  and  on  a  line  with  the  pneumogastric,* 
by  a  series  of  roots  which  are  continuous  with  the  roots  of  that  nerve,  the  glosso-pharyn- 
geal emerges  from  the  foramen  lacerum  posterius  through  a  fibrous  canal  which  is  prop- 
er to  it,  and  which  is  situated  in  front  of  the  canal  that  is  common  to  the  pneumogastric 
and  spinal  accessory  nerves ;  it  is  placed  to  the  inner  side  of  the  internal  jugular  vein, 
from  which  it  is  separated  by  a  cartilaginous  and  sometimes  osseous  lamina. 

During  its  passage  through  this  canal  it  presents  a  ganglionic  enlargement,  which  was 
described  by  Andersh  under  the  name  of  ganglion  petrosum,  and  is  now  more  generally 
known  as  the  ganglion  of  Andersh. 

This  ganglion  is  situated  in  a  depression  on  the  petrous  portion  of  the  temporal  bone 
{receptaculum  ganglii  petrosi) ;  from  it  the  nerve  pro-  Pig.  301. 

ceeds  as  a  rounded  cord,  which  descends  vertically 
(I,  fig.  301)  behind  the  styloid  muscle  in  front  of  the 
internal  carotid,  then  between  the  stylo-pharyngeus 
and  the  stylo-glossus,  and  passing  forward  so  as  to 
describe  a  curve  with  its  concavity  turned  upward, 
runs  in  front  of  the  posterior  pillar  of  the  fauces  and 
behind  the  tonsil,  and  then  passing  beneath  the  hyo- 
glossus  muscle  (2),  ramifies,  to  enter  the  base  of  the 
tongue  and  supply  the  mucous  membrane. 

During  this  course  it  gives  off  the  nerve  of  Jacob- 
son,  and  an  anastomotic  twig  to  the  facial  nerve  ;  it 
communicates  with  the  spinal  accessory  and  the 
pneumogastric ;  it  gives  off  a  muscular  branch  to 
the  digastricus  and  stylo-pharyngeus,  and  it  supplies 
some  carotid  filaments,  and  some  pharyngeal  and 
tonsillar  branches. 

The  Nerve  of  Jacobson. — In  order  to  facilitate  the 
study  of  the  course  of  this  nerve,  I  shall  first  de- 
scribe the  canals  through  which  it  passes  : 

Upon  the  ridge  which  separates  the  jugular  fossa 
from  the  carotid  canal,  to  the  outer  side  of  the  aqueduct  of  the  cochlea,  is  found  an  open- 
ing, which  is  the  inferior  orifice  of  the  canal  of  Jacobson.  This  canal  runs  backward 
and  upward  into  the  substance  of  the  internal  wall  of  the  cavity  of  the  tympanum,  in 
front  of  the  fenestra  rotunda  ;  there  it  branches  into  three  canals  :  one  descending,  which 
opens  into  the  carotid  canal ;  and  two  ascending  canals,  an  anterior,  which  runs  forward 
and  upward,  and  opens  into  the  groove  for  the  great  superficial  petrosal  or  cranial  branch 
of  the  vidian  nerve,  and  a  posterior,  which  at  first  ascends  vertically  behind  the  fenestra 
ovalis,  then  curves  suddenly  and  becomes  horizontal,  and  opens  upon  the  upper  surface 
of  the  pars  petrosa  in  a  groove  parallel  to  and  on  the  outer  side  of  the  groove  for  the 
cranial  branch  of  the  vidian  nerve. 

The  nerve  of  Jacobson,  which  comes  off  from  the  petrosal  ganglion,  or  ganglion  of  An- 
dersh, enters  this  canal.  In  one  subject  I  found  it  to  consist  of  two  filaments,  one  from 
the  pneumogastric,  and  the  other  from  the  glosso-pharyngeal.  t 

This  nerve  soon  divides  into  three  filaments  corresponding  to  the  three  branches  of  the 

*  Several  modern  physiologists,  believing  the  glosso-pharyngeal  to  be  a  mixed  nerve,  sensory  in  its  lingual 
portion,  and  motor  in  its  pharyngeal,  have,  therefore,  supposed  it  to  have  tviro  distinct  roots  :  a  larger,  which 
is  near  the  par  vagum,  and  a  smaller,  v^hich  lies  near  the  facial  nerve ;  and,  from  analogy,  they  regard  the 
former  as  the  sensory,  and  the  latter  as  the  motor  root. 

t  In  another  subject  it  was  formed  by  the  anastomoses  of  a  twig  from  the  auricular  branch  of  the  pneumo- 
gastric with  a  twig  from  the  glosso-pharyngeal. 


844  ■.i''.i:.:   il/    NEUROLOGY. 

canal ;  the  descending  filament  joins  the  carotid  plexus ;  of  the  two  ascending  lilaments, 
one  anastomoses  with  the  cranial  branch  of  the  vidian,  or  the  great  superficial  petrosal 
nerve  {v,  Jig.  300),  while  the  other  constitutes  the  small  superficial  petrosal  nerve,  which 
reaches  the  upper  surface  of  the  pars  petrosa  in  front  of  the  preceding,  and  terminates 
in  the  reddish  tissue  known  as  the  otic  ganglion.* 

It  follows,  therefore,  that  the  nerve  of  Jacobson  connects  the  glosso-pharyngeal  nerve 
with  the  superior  maxillary  division  of  the  fifth  nerve  (especially  with  the  spheno-pal- 
atine  ganglion  through  the  intervention  of  the  vidian  nerve),  with  the  otic  ganglion  of 
the  inferior  maxillary  division,  and  with  the  superior  cervical  ganglion  of  the  sympathetic. 

The  anastomotic  branch  to  the  facial  nerve  arises  from  the  ganglion  of  Andersh  imme- 
diately below  the  nerve  of  Jacobson  ;  it  runs  downward  and  outward  behind  the  styloid 
process,  is  then  reflected  upward,  so  as  to  describe  a  loop  with  its  concavity  turned  up- 
ward, and  anastomoses  with  the  facial  immediately  after  the  exit  of  that  nerve  from  the 
stylo-mastoid  foramen.  This  branch  appears  to  me  to  be  the  remaining  trace  of  a  con- 
siderable branch  of  the  facial  nerve,  which  I  have  seen  partially  supplying  the  place  of 
the  glosso-pharyngeal  (see  the  Tongue,  p.  646). 

The  Anastomosis  of  the  Glosso-pharyngeal  with  the  Spinal  Accessory  and  Pneumogastric 
Nerves. — Most  commonly  the  glosso-pharyngeal  runs  along  the  pneumogastric,  or,  more 
correctly,  along  the  anastomotic  branch  of  the  spinal  accessory.  Sometimes  it  is  com- 
pletely separated  from  these  nerves,  and  merely  communicates  with  them  by  means  of 
its  pharyngeal  branches. 

The  Branch  for  the  Bigastricus  and  Stylc-hyoideus. — This  branch  comes  off  from  the  outer 
side  of  the  nerve,  and  bifurcates  ;  one  of  its  divisions  enters  the  posterior  belly  of  the  digas- 
tricus,  and  the  other  supplies  the  stylo-pharyngeus  and  stylo-hyoideus.  It  has  already  been 
stated  that  this  branch  anastomoses  with  the  facial  nerve  in  the  digastric  muscle. 

The  Carotid  Filaments. — These  are  very  numerous ;  they  descend  along  the  internal 
carotid  artery,  and,  having  reached  the  point  of  bifurcation  of  the  common  carotid,  anas- 
tomose with  the  carotid  filaments  of  the  superior  cervical  ganglion,  and  assist  in  form- 
ing the  arterial  plexus.  I  have  not  been  able  to  trace  them  below  the  bifurcation  of  the 
common  carotid.     Some  of  these  filaments  are  described  as  joining  the  cardiac  nerves. 

The  Pharyngeal  Branches. — These  are  two  or  three  in  number  ;  they  anastomose  with 
the  pharyngeal  branches  of  the  pneumogastric,  to  constitute  the  pharyngeal  plexus.  These 
branches  evidently  supply  the  middle  and  superior  constrictors.  The  filaments  for  the 
latter  muscles  are  reflected  upward  upon  the  posterior  surface  of  the  pharynx. 

The  tonsillar  branches  are  very  numerous,  and  form  a  sort  of  plexus. 

The  Lingual  Branches. — After  having  given  off  the  different  branches  above  mentioned, 
the  glosso-pharyngeal,  reduced  to  half  its  original  size,  enters  the  base  of  the  tongue,  and 
then  r-amifies  ;  some  of  its  lingual  branches  lie  close  beneath  the  mucous  membrane  ; 
others  traverse  the  upper  layers  of  the  muscular  substance  of  the  tongue  to  proceed  to 
the  mucous  membrane  in  front  of  the  preceding  branches  ;  they  are  all  intended  for  the 
mucous  membrane  ;  the  internal  branches  proceed  from  without  inward  at  the  side  of  the 
median  line,  while  the  external  runs  along  the  border  of  the  tongue  ;  I  have  never  seen 
any  filament  terminating  in  the  muscular  fibres. 

Function. — From  its  distribution,  this  nerve  must  be  regarded  as  a  motor  nerve  for  the 
pharynx,  and  a  sensory  nerve  for  the  base  of  the  tongue. 

The  Second  Portion  of  the  Eighth  J^erve,  or  the  Pneumogastric  Jferve. 

Dissection. — Lay  open  the  back  part  of  the  foramen  lacerum  posterius,  and  afterward 
examine  the  nerve  in  the  different  parts  of  its  course  successively. 

The  pneumogastric  nerve,  called  also  the  vagus  nerve,  the  par  vagum,  and  the  tenth  era/- 
niaX  nerve  of  some  modern  authors,  is  the  principal  branch  of  the  eighth  nerve  (8,  fig.  301), 
and  is  one  of  the  most  remarkable  nerves  in  the  body,  both  on  account  of  the  extent  of 
its  distribution,  and  of  the  importance  of  the  organs  supplied  by  it.  It  supplies  branches, 
on  the  one  hand,  to  the  larynx,  the  lungs,  and  the  heart ;  and,  on  the  other,  to  the  pharynx, 
the  oesophagus,  the  stomach,  and  the  solar  "plexus. 

It  has  already  been  stated  that  this  nerve  arises  from  the  upper  part  of  the  medulla  ob- 
longata, upon  the  restiform  bodies,  and  in  a  line  with  the  posterior  roots  of  the  spinal 
nerves  ;  that  its  filaments  of  origin  converge,  and  then  unite  at  first  into  seven  or  eight 
fasciculi,  and  then  into  a  single  cord,  which  passes  towards  the  foramen  lacerum  poste- 
rius, through  which  it  emerges  from  the  cranium.  The  pneumogastric  nerve  then  mns 
vertically  {p,fig.  301)  in  the  neck  along  the  vertebral  column,  enters  the  thorax,  runs 
along  the  oesophagus,  with  which  it  passes  through  the  diaphragm,  and  terminates  on 
the  stomach  and  in  the  solar  plexus. 

We  shall  now  proceed  to  examine  this  nerve  while  it  is  within  the  foramen  lacerum 

*  Arnold  admits  six  filaments  for  the  nerve  of  Jacobson,  and,  consequently,  six  small  ducts  as  branches  of 
the  canal  of  Jacol)son  ;  these  six  filaments  consist  of  the  three  described  in  the  text  above,  and  of  a  twig  for 
the  fenestra  rotunda,  one  for  the  fenestra  ovalis,  and  one  for  the  Eustachian  tube.  I  have  distinctly  seen  the 
twig  for  the  fenestra  ovalis,  that  is  to  say,  a  twig  which  reaches  the  margin  of  the  fenestra  ovalis,  but  cannot 
be  traced  any  farther.  I  have  also  seen  the  twig  which  passes  to  the  Eustachian  tube  ;  but  I  have  not  yet 
been  able  to  find  the  twig  for  the  fenestra  rotunda. 


THE    PNEUMOGASTEIC   NERVE.  845 

posterius  ;  as  it  is  emerging  from  that  foramen ;  and  as  it  descends  in  the  neck,  in  the 
thorax,  and  in  the  abdomen. 

The  Pneumogastric  Nerve  witfdn  th£  Foramen  Lacerum  Posterius. 

At  the  foramen  lacerum  posterius,  the  pneumogastric  nerve  passes  through  the  same 
opening  as  the  spinal  accessory,  which  lies  in  contact  with  it ;  a  fibrous,  cartilaginous, 
or  bony  septum  separates  it  from  the  glosso-pharyngeal,  which  lies  in  front  of  it ;  and  an- 
other cartilaginous  and  often  bony  septum  separates  it  from  the  internal  jugular  vein. 

As  it  is  passing  through  the  foramen  it  presents  a  well-marked  ganghonic  structure ; 
I  would  say,  rather,  a  gray  substance  containing  white  nervous  filaments,  but  without  any 
observable  swelling  :  hence  most  anatomists  have  denied  the  existence  of  a  ganglion  at 
this  spot. 

To  this  ganglion,  the  ganglion  of  the  pneumogastric,  which  may  be  compared  to  the 
Gasserian  ganglion  and  to  the  inter-vertebral  ganglia,  the  spinal  accessory  nerve  is  ap- 
phed,  and  is  connected  with  it  by  several  very  delicate  filaments.  I  have  already  sta- 
ted that,  not  unfrequently,  the  highest  roots  of  the  spinal  accessory  nerve  join  the  pneu- 
mogastric directly. 

This  ganglion  gives  off  an  anastomotic  twig,  which  enters  the  petrosal  ganglion  of  the 
glosso-pharyngeal :  I  have  not  always  found  this  filament ;  it  also  gives  an  anastomotic 
branch  to  the  facial  nerve,  viz.,  the  auricular  branch  of  the  pneumogastric  of  Arnold.  This 
branch  might  be  called,  the  branch  of  the  jugular  fossa ;  it  can  be  very  well  seen  through 
the  coats  of  the  jugular  vein  when  that  vessel  is  laid  open.  It  runs  along  the  anterior 
part  of  the  jugular  fossa,  between  it  and  the  internal  jugular  vein,  gives  off  an  anasto- 
motic twig  to  the  nerve  of  Jacobson,  enters  the  temporal  bone  through  an  opening  in  the 
jugular  fossa,  near  the  styloid  process,  and  traverses  a  very  short  canal,  which  conducts 
it  directly  into  the  Fallopian  aqueduct,  in  which  it  anastomoses  with  the  facial  nerve.* 

The  Pneumogastric  Nerve,  at  its  Exit  from  the  Foramen  Lacerum  Posterius. 

At  its  exit  from  the  foramen  lacerum  posterius,  the  pneumogastric  nerve  presents  the 
appearance  of  a  plexiform  cord,  which  is  often  accompanied  by  the  gray  matter  of  the 
ganglion  for  the  space  of  about  six  lines  or  an  inch.  This  plexiform  cord  has  certain 
important  connexions  with  the  spinal  accessory,  the  ninth  or  hypo-glossal  nerve,  the  glos- 
so-pharyngeal nerve,  and  the  superior  cervical  ganglion. 

It  is  joined  by  one  of  the  branches  of  bifurcation  of  the  spinal  accessory,  which  we 
shall  name  the  internal  or  anastomotic  branch  ol  the  spinal  accessory  nerve  ;  it  becomes 
applied  to  the  pneumogastric  nerve,  and  may  be  distinguished  from  it  for  a  considerable 
distance. 

It  also  anastomoses  with  the  hypo-glossal,  at  the  point  where  it  is  crossed  by  that 
nerve,  and  at  other  times  above  that  point.  This  anastomosis,  moreover,  is  subject  to 
great  variety  ;  sometimes  it  takes  place  by  a  very  small  filament,  at  other  times  by  two 
or  three  twigs,  which  form  a  sort  of  plexus. 

It  also  anastomoses  with  the  glosso-pharyngeal.  The  examination  of  this  anastomo- 
sis, after  the  parts  had  been  macerated  in  diluted  nitric  acid,  enabled  me  to  see  that  it 
is  not,  properly  speaking,  effected  with  the  pneumogastric  nerve,  but  with  the  anasto- 
motic branch  of  the  spinal  accessory.  Nothing  can  be  more  variable  than  these  anasto- 
moses, which  are  sometimes  wanting  on  one  side,  and  which  are  rather  frequently  ef- 
fected through  the  intervention  of  the  pharyngeal  branches. 

Lastly,  the  pneumogastric  nerve  commu)iicates  with  the  great  sympathetic  by  one  or 
two  branches  in  man  and  some  mammalia  ;t  in  the- other  classes  of  animals  the  con- 
nexion is  so  intimate  that  it  is  altogether  impossible  to  separate  the  pneumogastric  from 
the  superior  cervical  ganghon. 

The  connexions  of  the  pneumogastric  with  the  spinal  accessory  and  superior  cervical 
ganghon  are  two  very  important  points  in  its  anatomy,  t 

The  Pneumogastric  Nerve  in  the  Neck. 

In  the  cervical  region,  the  pnemnogastric  nerve  {p,figs.  298,  300,  301)  is  situated  in 
front  of  the  vertebral  column,  the  praevertebral  muscles  intervening  between  them,  upon 
the  side  of  the  pharynx  and  oesophagus,  and  between  the  internal  and  then  the  common 
carotid,  which  are  on  its  inner  side,  and  the  jugular  vein,  which  is  on  its  outer  side  ;  it  is 
placed  behind  these  vessels.    It  is  closely  applied  to  the  carotid  artery,  being  in  the  same 

*  I  have  seen  this  branch,  immediately  after  its  origin,  enter  the  sheath  of  the  glosso-pharyngeal  nerve,  run 
along  its  ganglion,  and  then  curve  backward  to  enter  the  jugular  fossa.  Arnold,  who  first  described  this  anas- 
tomotic branch,  represents  it  as  divided  into  three  filaments  :  an  ascending,  which  anastomoses  with  the  trunk 
of  the  facial  nerve  ;  a  descending,  which  anastomoses  with  the  posterior  auricular  branch  of  the  same  nerve  ; 
and  a  middle  {u,fig.  299),  which  ramifies  upon  the  external  auditory  meatus. 

t  I  have  seen  the  pneumogastric  nerve  communicate  with  the  great  sympathetic,  by  filaments  which  come 
off  at  different  heights  from  the  cervical  ganglion ;  two  proceeded  from  tlie  upper  part  of  the  superior  cervical 
ganglion,  and  then  ascended  ;  and  two  came  from  the  lower  part  of  the  ganglion,  and  descended  to  unite  with 
the  pneumogastric.  I  have  met  with  a  case  in  which  the  superior  cervical  ganglion  was  applied  in  its  whole 
extent  so  closely  to  the  pneumogastric  that  it  was  impossible  to  separate  them. 

t  [The  pneumogastric  also  receives  a  filament  from  the  anastomotic  loop  of  the  first  and  second  cervical 
iif  rvcs  (see  p.  777). J 


846  NEUROLOGY. 

sheath :  it  is  separated  from  the  cervical  portion  of  the  great  sympathetic  (i),  which  lies 
behind  and  to  the  outer  side  of  it,  by  a  great  quantity  of  cellular  tissue. 

During  this  course  it  supplies  the  pharyngeal  branch,  the  superior  laryngeal  nerve,  and 
the  cardiac  filaments. 

The  Pharyngeal  Branch,  or  Small  Pharyngeal  Nerve. — This  is  often  double,  and  is  then 
distinguishable  into  a  superior  and  an  inferior ;  it  comes  off  at  a  little  distance  from  the 
foramen  lacerum  posterius,  but  its  real  origin  is  variable.  In  some  cases  it  arises  ex- 
clusively from  the  pneumogastric ;  at  other  times  exclusively  from  the  anastomotic 
branch  of  the  spinal  accessory,  which,  as  already  stated,  does  not  become  immediately 
blended  with  the  pneumogastric  ;  and  it  often  arises  both  from  the  pneumogastric  and 
the  spinal  accessory :  lastly,  the  glosso-pharyngeal  sometimes  gives  it  a  filament.  It 
passes  behind  the  internal  carotid,  gives  off"  some  carotid  filaments,  which  join  the  more 
numerous  twigs  from  the  glosso-pharyngeal,  and  then  anastomoses  with  the  ramifica- 
tions of  the  glosso-pharyngeal,  and  with  several  large  branches  from  the  superior  cervi- 
cal ganglion,  to  form  the  pharyngeal  plexus,  which  is  one  of  the  most  remarkable  plex- 
uses in  the  body,  and  to  which  the  varied  and  frequent  nervous  phenomena  observed  in 
that  region  must  be  referred.  I  shall  recur  to  this  plexus  when  describing  the  great 
sympathetic. 

The  Superior  Laryngeal  Nerve  {x',fig.  301). — This  is  larger  than  the  pharyngeal  branch ; 
it  comes  off"  from  the  inner  side  of  the  pneumogastric*  as  a  rounded  cord,  which  may  be 
traced  as  high  as  the  ganglion  of  the  nerve  ;  it  passes  downward  and  inward  upon  the 
side  of  the  pharynx,  behind  the  internal  and  external  carotid  arteries,  which  it  crosses 
obliquely :  it  then  turns  forward  and  inward  to  gain  the  thyro-hyoid  membrane,  passing 
above  the  upper  margin  of  the  inferior  constrictor  of  the  pharynx ;  it  runs  for  some 
time  between  the  thyro-hyoid  muscle  and  the  thyro-hyoid  membrane,  perforates  the  lat- 
ter at  the  side  of  the  median  line,  and  then  enters  the  substance  of  the  ar)rteno-epiglot- 
tid  fold  of  mucous  membrane,  where  it  terminates  by  dividing  into  a  great  number  of  fil- 
aments. 

During  its  course,  it  gives  off  a  branch  which  is  called  the  external  laryngeal  (y),  and 
which  I  have  seen  arise  directly  from  the  pneumogastric  itself;  this  branch  communi- 
cates with  the  superior  cervical  ganglion  by  one  or  two  filaments,  and  passes  inward  and 
downward  upon  the  side  of  the  larynx.  It  gives  off  one  or  two  filaments,  which  anasto- 
mose with  the  superior  cardiac  nerve,  behind  the  common  carotid ;  Haller  calls  this 
communication  between  the  external  laryngeal  and  the  great  sympathetic  the  laryn- 
geal plexus. \  The  external  laryngeal  nerve  also  gives  off  several  branches  to  the  infe- 
rior constrictor  of  the  pharynx,  some  to  join  the  pharyngeal  plexus,  and  some  twigs  to 
the  thyroid  gland  ;  it  then  passes  downward  and  forward  between  the  inferior  constric- 
tor and  the  thyroid  cartilage,  and  terminates  by  ramifying  in  the  crico-thyroid  muscle. 

The  terminal  expansion  of  the  superior  laryngeal  nerve  is  remarkable  for  its  radiated 
arrangement ;  it  is  preceded  by  a  flattening  and  thickening  of  the  nerve.  These  ex- 
panded branches  are  all  sub-mucous,  and  may  be  arranged  into  the  anterior  or  epiglottid, 
and  the  posterior. 

The  anterior  or  epiglottid  branches  are  numerous  and  small ;  they  run  upon  the  margin, 
and  on  the  fore  part  of  the  epiglottis  ;  some  of  them  reach  its  free  extremity,  others  run 
between  the  fibro-cartilage  of  the  epiglottis  and  the  adipose  tissue,  called  the  epiglottid 
gland ;  some  of  them  perforate  the  epiglottis,  and  ramify  upon  its  posterior  surface. 

Among  these  anterior  terminal  filaments  of  the  superior  laryngeal  nerve  there  is  at 
least  one  which  runs  forward  under  the  mucous  membrane  covering  the  base  of  the 
tongue,  and  may  be  traced  as  far  as  the  two  rows  of  glands,  which  are  arranged  like  the 
letter  V.  These  filaments  of  the  superior  laryngeal  nerve  to  the  tongue  are  placed  be- 
tween the  lingual  branches  of  the  right  and  left  glosso-pharyngeal  nerves,  with  which 
they  have  probably  been  confounded. 

The  posterior  or  laryngeal  filaments  contained  in  the  aryteno-epiglottid  fold  are  more 
numerous  than  the  anterior  branches ;  they  are  divided  into  the  mucous  filaments,  the 
arytenoid  filament,  and  the  anastomotic  or  descending  filameiit. 

The  mucous  filaments  are  very  numerous,  and  run  upward  in  the  aryteno-epiglottid 
fold ;  some  of  them  lie  beneath  the  external,  and  others  beneath  the  internal  layer  of 
mucous  membrane  of  this  fold.  They  are  intended  for  these  two  layers,  and  they  ter- 
minate, for  the  most  part,  at  the  superior  orifice  of  the  larynx :  their  number  explains 
the  exquisite  sensibility  of  this  opening.  Some  of  these  mucous  filaments  may  be  traced 
into  the  substance  of  the  arytenoid  glands. 

The  filatnent  for  the  arytenoid  muscle  is  very  liable  to  be  confounded  with  the  mucous 

*  It  arises,  therefore,  on  the  opposite  side  to  the  anastomotic  branch  of  the  spinal  accessory,  which  has  not 
appeared  to  me  to  assist  in  its  formation.  I  have  seen  the  superior  laryngeal  arise  by  two  roots,  the  larger  of 
which  came  from  the  pneumogastric,  while  the  other,  which  was  very  small,  came  from  the  glosso-pharyn- 
geal. It  appears  to  me  that  M.  BischofTs  remarks  concerning  the  origin  of  the  superior  laryngeal  nerve  on  a 
level  with  tlie  spinal  accessory,  would  apply  to  the  pharyngeal  branch  of  the  pneumogastric. 

t  The  superior  laryngeal  nerve  (x',Jig.  301)  forms  a  loop  behind  the  carotids,  like  tliat  formed  by  the  hypo- 
glossal (d)  in  front  of  them,  but  lower  down  in  the  neck  ;  that  portion  of  the  nerve  which  runs  between  the 
thyro-hyoid  membrane  and  the  thyro-hyoid  muscle  is  exceedingly  tortuous  in  some  positions  of  the  larynx. 


THE  PNEUMOGASTRIC  NERVE  IN  THE  THORAX,  ETC.       847 

filaments  ;  it  perforates  the  muscle  from  behind  forward,  and  is  partly  distributed  to  it 
and  partly  to  the  lining  membrane  of  the  larynx. 

The  descending  or  anastomotic  filament,  which  is  small,  but  of  variable  size,  descends 
vertically,  between  the  mucous  membrane  on  the  one  hand,  and  the  thyro-  and  crico- 
arytenoid muscles  on  the  other,  gains  the  posterior  surface  of  the  cricoid  cartilage,  and 
anastomoses  upon  it  with  the  recurrent  laryngeal  nerve.  This  remarkable  anastomosis 
was  known  to  Galen.* 

Thus,  the  superior  laryngeal  nerve  chiefly  belongs  to  the  mucous  membrane  of  the 
larynx ;  but  it  gives  branches  to  the  arytenoid  and  crico-thyroid  muscles :  the  branch 
for  the  latter  comes  from  the  external  laryngeal  division  of  this  nerve. 

The  Cardiac  Branches  of  the  Pneumogastric  Nerve  of  the  Neck. — These  vary  both  in 
number  and  size  in  different  subjects,  and  even  upon  the  two  sides  of  the  same  body  : 
they  come  off  at  different  heights  from  the  trunk  of  the  pneumogastric  ;  some  of  them, 
after  a  course  of  variable  extent,  join  the  superior  cardiac  nerves,  either  in  the  neck  or 
in  the  thorax ;  the  others  pass  directly  to  the  cardiac  plexus.  The  most  remarkable  of 
the  cervical  cardiac  branches  of  the  pneumogastric  is  that  which  comes  off  at  the  lower 
part  of  the  neck,  a  little  above  the  first  rib  ;  on  the  right  side,  it  descends  in  front  of  the 
common  carotid,  and  then  in  front  of  the  brachio-cephalic  artery,  below  which  it  anasto- 
moses with  the  superior  cardiac  nerve.  On  the  left  side,  it  passes  in  front  of  the  arch 
of  the  aorta,  and  anastomoses  below  that  vessel  with  the  superior  cardiac  nerve  of  that 
side.   This  branch  sometimes  goes  directly  to  the  cardiac  plexus :  it  is  sometimes  double. 

The  Pneumogastric  Nerve  in  the  Thorax. 

The  thoracic  portion  of  the  pneumogastric  nerve  presents  this  peculiarity,  that  it  differs 
remarkably  on  the  right  and  left  sides. 

On  the  right  side,  the  nerve  {p,fig-  302)  enters  the  thorax  between  the  sub-claviaa 
vein  and  artery  :  lower  down,  it  passes  behind  the  brachio-cephalic  vein  and  the  supe- 
rior cava,  and  behind  the  phrenic  nerve,  at  the  side  of  the  trachea,  or,  rather,  in  the 
groove  between  the  trachea  and  oesophagus  :  it  then  passes  behind  the  root  of  the  lung, 
where  it  becomes  flattened  and  enlarged,  gives  off  a  great  number  of  branches,  and  ap- 
pears to  expand,  in  order  to  unite  in  a  different  arrangement.  Below  the  root  of  the 
lung  the  right  pneumogastric  is  always  divided  into  two  flattened  branches,  which  run 
along  the  right  side  of  the  cesophagus,  join  together  at  a  short  distance  from  the  dia- 
phragm, and  pass  behind  the  cesophagus,  with  which  canal  the  common  trunk  enters  the 
abdomen. 

On  the  left  side,  the  pneumogastric  enters  the  thorax  between  the  common  carotid  and 
the  sub-clavian  artery,  in  the  triangular  interval  between  those  vessels,  internal  to  and 
then  behind  the  phrenic  nerve,  behind  the  brachio-cephalic  vein,  and  to  the  left  of  the 
arch  of  the  aorta  ;t  it  then  passes  behind  the  left  bronchus,  upon  which  it  ramifies,  and 
unites  again  into  one  or  two  branches,  which  pass  in  front  of  the  oesophagus,  and  enter 
the  abdomen  with  it. 

In  the  thorax  the  pneumogastric  gives  off  the  recurrent  or  inferior  laryngeal  nerve,  a 
cardiac  branch,  some  tracheal  and  oesophageal  branches,  and  branches  to  the  anterior  and 
posterior  pulmonary  plexuses. 

The  Recurrent  or  Inferior  Laryngeal  Nerve.t 

This  nerve  (r,  fig.  302),  so  called  on  account  of  its  reflected  course,  arises  in  front  of 
the  arch  of  the  aorta  on  the  left  side,  and  of  the  sub-clavian  artery  on  the  right  side  :  it 
is  sometimes  so  large  that  it  may  be  regarded  as  resulting  from  the  bifurcation  of  the 
pneumogastric  :  it  is  reflected  below  and  then  behind  the  arch  of  the  aorta  on  the  left 
side,  and  the  sub-clavian  artery  on  the  right,  so  as  to  form  a  loop  or  arch,  which  has  its 
concavity  turned  upward,  and  which  embraces  the  corresponding  vessel.  Having  thus 
changed  its  course  from  a  descending  to  an  ascending  one,  the  recurrent  nerve  enters 
the  groove  {q,fig.  301)  between  the  trachea  and  the  oesophagus,  and  continues  to  ascend 
as  high  as  the  lower  border  of  the  inferior  constrictor  muscle  of  the  pharynx ;  it  then 
passes  beneath  that  muscle,  gives  some  filaments  to  it,  runs  behind  the  lesser  cornu  of 
the  thyroid  cartilage  and  the  crico-thyroid  articulation,  along  the  outer  border  of  the 
posterior  crico-arytenoid  muscle,  and  terminates  by  ramifying  in  the  muscles  of  the 
larynx. 

During  its  course,  the  recurrent  nerve  gives  off  the  following  collateral  branches :  at 
the  point  of  its  reflection,  it  gives  several  cardiac  filaments,  which  unite  with  the  cardiac 
branches  of  the  pneumogastric  and  great  sympathetic.  It  is  important  to  remark  the 
intimate  connexion  which  exists  between  the  recurrent  and  the  cardiac  nerves  :  some 
very  considerable  anastomoses  are  almost  always  found  between  the  superior  and  infe- 

*  See  note,  p.  848. 

t  The  relation  of  the  pneumogastric  with  the  arch  of  the  aorta  explains  the  stretching  and  atrophy  of  this 
nerve  in  aneurisms  of  that  portion  of  the  vessel. 

1  Those  anatomists  who  regard  the  superior  laryngeal  nerve  as  a  dependance  of  the  spinal  accessory  be- 
lieve that  the  inferior  or  recurrent  laryngeal  has  a  similar  origin.  I  may  repeat,  and  with  still  more  reason,  in 
reference  to  this  nerve,  what  I  have  already  stated  in  regard  to  the  superior  laryngeal,  that  it  is  impossible  to 
'«monstrate  this  continuity  by  dissection. 


848  NEUROLOGY. 

rior  cardiac  nerves  and  the  recurrent  nerve  :  sometimes,  indeed,  the  recurrent  nerve 
forms  the  point  at  which  the  superior  and  middle  cardiac  nerves  meet,  and  from  which 
the  inferior  cardiac  nerve  is  given  off;  the  anastomoses  between  the  recurrent  and  car- 
diac nerves  sometimes  form  a  true  plexus. 

The  recurrent  also  gives  oesophageal  branches,  which  are  much  more  numerous  on  the 
left  than  on  the  right  side,  so  that  the  left  recurrent  nerve  is  much  smaller  in  the  larynx 
than  the  right  nerve. 

It  also  gives  tracheal  branches,  which  chiefly  supply  the  posterior  or  membranous  por- 
tion of  that  canal. 

And,  lastly,  some  pharyngeal  filaments,  all  of  which  are  destined  for  the  inferior  con- 
strictor. 

Excepting  an  anastomotic  branch*  for  the  superior  laryngeal  nerve,  all  of  the  terminal 
branches  of  the  recurrent  nerve  are  intended  for  the  muscles  of  the  larynx,  and  are  thus 
distributed : 

The  branch  for  the  posterior  crico-arytenoid  simply  enters  that  muscle. 

The  branch  for  the  arytenoid,  runs  between  the  cricoid  cartilage  and  the  posterior  crico- 
arytenoid muscle,  and  then  ramifies  in  the  arytenoid.  It  has  already  been  stated  that 
the  last-named  muscle  is  also  supplied  by  the  superior  laryngeal  nerve. 

The  branch  for  the  lateral  crico-arytenoid  and  thyro-arytenoid  muscles  is  the  true  termina- 
tion of  the  nerve  ;  it  passes  on  the  outer  side  of  these  two  muscular  bundles,  which,  as 
formerly  stated,  constitute  a  single  muscle  in  the  human  subject,  and  then  enters  them 
by  very  delicate  filaments.  I  have  distinctly  seen  a  very  delicate  filament  entering  the 
crico-th)Toid  articulation. 

After  the  pneumogastric  has  given  off  the  recurrent  nerve,  and  often  before  doing  so, 
it  furnishes  certain  cardiac  branches  (thoracic  cardial) ;  these  are  subdivided  into  the 
pericardial,  which  run  upon  the  outer  surface  of  the  pericardium,  and  are  lost  in  it  and 
in  the  cellular  tissue  which  replaces  the  thymus  ;  and  into  the  cardiac  branches,  properly 
so  called,  which  assist  in  the  formation  of  the  cardiac  plexus. 

The  pneumogastric  also  gives  off  certain  anterior  pulmonary  branches,  which  run  in 
front  of  the  bronchus  and  of  the  pulmonary  arteries  and  veins,  cross  obliquely  over  them, 
and  then  enter  the  substance  of  the  lung,  following  the  ramifications  of  the  air-tubes  and 
bloodvessels  ;  these  pulmonary  branches  form  what  is  called  the  anterior  pulmonary  plex- 
us. I  have  seen  several  of  them  extend  some  considerable  distance  beneath  the  serous 
membrane,  covering  the  inner  surface  of  the  lungs,  before  they  entered  the  substance 
of  those  organs. 

Behind  the  bronchus,  and  along  the  oesophagus,  the  pneumogastric  nerve  gives  off 
posterior  branches,  consisting  of  a  great  number  of  esophageal  branches  ;  of  some  tracheal 
branches,  which  principally  supply  the  back  or  membranous  portion  of  the  trachea  ;  and, 
lastly,  of  posterior  pulmonary  or  bronchial  branches,  which  form  the  posterior  pulmonary 
plexus. 

The  posterior  pulmonary  plexus  is  one  of  the  most  remarkable  in  the  body  ;  in  it  the 
pneumogastric  nerve  appears  to  be  decomposed  and  expanded ;  there  is  a  right  and  a 
left  pulmonary  plexus.  The  left  is  much  larger  than  the  right.  The  two  plexuses  are 
not  independent  of  each  other,  but  are  connected  by  free  anastomoses  :  this  remarkable 
disposition  establishes  a  community  of  function  between  the  two  nerves,  and  explain* 
how  one  of  them  may  supply  the  place  of  the  other. 

The  pulmonary  plexuses,  which  are  completed  by  filaments  from  the  great  sympathetic, 
are  situated  behind  the  root  of  each  lung,  or,  to  speak  more  exactly,  behind  the  bronchi 
(whence  the  name  of  bronchial  plexuses).  A  few  of  the  twigs  emerging  from  them  follow 
the  pulmonary  arteries,  and  appear  to  be  lost  in  their  coats  ;  the  others  accompany  the 
bronchi,  some  of  them  passing  behind  these  canals,  and  others,  being  reflected  forward 
in  the  angles  formed  by  their  bifurcation,  run  along  their  anterior  aspect,  and  terminate 
in  their  parietes.  They  may  be  traced  as  far  as  the  ultimate  ramifications  of  the  aii- 
tubes.  In  large  animals  they  can  be  easily  seen  entering  the  circular  muscular  fibres 
which  surround  the  bronchial  tubes,  t 

Below  the  pulmonary  plexus,  the  pneumogastric  merely  gives  off  certain  cesophagcal 
branches,  which  surround  the  oesophagus  in  very  great  numbers.  The  right  and  left 
pneumogastric  nerves  anastomose  with  each  other ;  but  the  communicating  arches  do 
not  constitute  those  circular  anastomoses,  which  have  been  so  decidedly  said  to  explain 
the  pain  caused  by  swallowing  too  large  a  morsel  of  food. 

The  Pneumogastric  Nerve  in  the  Abdomxn. 
The  two  pneumogastrics  enter  the  abdomen  with  the  oesophagus,  the  left  nerve  being 
in  front  and  the  right  nerve  behind  that  canal,  and  are  distributed  in  the  following  manner : 

*  [This  anastomotic  branch  is  superficial,  and  joins  the  descending  filament  from  the  superior  laryngeal 
nerve,  beneath  the  mucous  membrane  on  the  back  of  the  larynx,  and  sometimes  sends  filaments  into  the  ary- 
tenoid muscle  ;  there  is,  generally,  a  second  anastomosis  between  the  superior  and  inferior  laryngeal  nerves 
on  the  side  of  the  larynx,  between  the  thyroid  cartilage  and  the  thyro-arytenoid  muscle.] 

t  I  have  seen  a  nerve  from  the  pulmonary  plexus  pass  through  some  of  the  fibres  of  the  oesophagus  and  ram- 
ify iu  the  aorta. 


SPJNAL    ACCESSORY    NERVE    OF    WILLIS.  849 

The  left  nerve  {q,fig.  302),  which  is  situated  in  front  of  the  cardia,  expands  into  a  very- 
great  number  ot  diverging  filaments,  some  of  which  extend  over  the  great  cul-de-sac, 
and  others  over  the  anterior  surface  of  the  stomach ;  but  the  greater  number  gain  the 
lesser  curvature,  and  divide  into  two  sets  or  groups  ;  one  of  these  leaves  the  lesser  cur- 
vature, enters  the  gastro-hepatic  omentum,  is  conducted  by  it  to  the  transverse  fissure 
of  the  liver,  and  enters  that  gland.  The  other  group  continues  in  the  lesser  curvature, 
and  may  be  traced  as  far  as  the  duodenum. 

The  right  pneumogastric  (p'),  situated  behind  the  cardia,  gives  a  much  smaller  number 
of  branches  to  the  stomach  than  the  left,  and  joins  the  solar  plexus  (z),  of  which  it  may 
be  regarded  as  one  of  the  principal  origins. 

Summary  of  the  Distrilmtion  of  the  Pneumogastric  Nerve. — This  nerve,  it  wiU  be  seen, 
has  an  extremely  complicated  distribution. 

Within  the  foramen  lacerum  posterius,  it  anastomoses  with  the  spinal  accessory  ;  with 
the  facial  nerve  by  means  of  the  auricular  branch  of  Arnold,  or  the  branch  of  the  jugular 
fossa ;  and  with  the  nerve  of  Jacobson,  and,  therefore,  with  the  glosso-pharyngeal  nerve, 
by  a  twig  from  the  same  auricular  branch. 

At  its  exit  from  the  foramen  lacerum  posterius,  it  anastomoses  with  a  Isirge  branch  of  the 
spinal  accessory  ;  with  the  hypo-glossal ;  with  the  glosso-phyrangeal ;  and  with  the  su- 
perior cervical  ganglion. 

In  the  neck,  it  gives  off  the  pharyngeal  branch  or  small  pharyngeal  nerve,  the  superior 
laryngeal  nerve,  and  the  superior  cardiac  branches  of  the  pneumogastric. 

In  the  thorax,  it  gives  off  the  recurrent  or  inferior  laryngeal  nerve,  which  supplies 
some  cardiac,  oesophageal,  pharyngeal,  tracheal,  and  laryngeal  branches ;  the  inferior 
cardiac  branches  ;  and  the  pulmonary  or  bronchial  branches. 

In  regard  to  its  structure,  the  pneumogastric  differs  essentially  from  the  other  cerebro- 
spinal nerves,  by  the  tenuity  of  its  filaments  and  by  their  plexiform  arrangement ;  and 
in  both  of  these  particulars,  as  well  as  in  its  distribution,  it  rather  resembles  the  nerves 
of  organic  than  those  of  animal  life.  In  the  description  of  the  sympathetic  it  will  be 
seen  how  intimate  are  its  relations  with  the  pneumogastric  nerve. 

Functions  of  the  Pneumogastric. — From  the  manner  in  which  the  pneumogastric  is  dis- 
tributed, it  follows  that  it  is  a  nerve  both  of  sensation  and  ot  motion ;  for  it  supplies 
both  the  lining  membrane  of  the  respiratory  and  digestive  passages,  and  the  muscles 
and  muscular  coats  of  the  same  canals.  Anatomy  does  not  confirm  the  ingenious  idea 
of  Bischoff,  that  the  pneumogastric  is  essentially  a  nerve  of  sensation,  and  that  the  por- 
tion which  appears  to  be  motor  really  belongs  to  the  spinal  accessory.  Physiologists 
have  studied  the  influence  of  the  pneumogastric  upon  the  larynx,  the  lungs,  the  heart, 
and  the  stomach  in  an  infinite  variety  of  ways  ;  it  appears,  from  some  experiments 
which  I  made  upon  this  subject,  that  animals  in  which  both  pneumogastrics  are  simul- 
taneously cut  die  almost  immediately,  when  they  are  permitted  to  eat  as  much  as  they 
please  ;  for,  the  contractility  of  the  stomach  and  oesophagus  being  destroyed,  the  food, 
after  having  filled  the  stomach,  distends  the  oesophagus,  and  passes  from  it  into  the  larynx. 

The  Third  Portion  of  the  Eighth  Jferve,  or  the  Spinal  Accessory  JN'&rve  oj 

Willis. 

We  have  already  described  the  very  remarkable  origin  of  the  spmal  accessory  nerve 
at  the  side  of  the  cervical  portion  of  the  spinal  cord,  between  the  anterior  and  posterior 
roots  of  the  spinal  nerves,  or,  rather,  immediately  in  front  of  the  posterior  roots,  of 
which  it  appears  to  be  a  dependance  :  we  particularly  alluded  to  the  arrangement  of  its 
highest  filaments  of  origin,  which  come  from  the  restiform  bodies,  and  are  continuous 
above  with  the  roots  of  the  pneumogastric,  so  that  they  sometimes  even  join  that  nerve, 
and  below  with  the  posterior  roots  of  the  spinal  nerves. 

Lastly,  we  have  pointed  out  the  varieties  of  its  origin,  its  connexions  with  the  first 
pair  of  cervical  nerves,  of  which  it  almost  always  forms  the  posterior  roots,  its  ascend- 
ing course  to  the  foramen  magnum,  through  which  it  enters  the  cranium,  and  its  exit 
from  the  scull  by  the  foramen  lacerum  posterius. 

It  emerges  from  the  foramen  lacerum  posterius  by  an  opening  quite  distinct  from  that 
for  the  glosso-pharyngeal,  but  common  to  itself  and  the  pneumogastric  nerve,  behind 
which  it  is  situated  {9,  fig.  301).  While  passing  through  the  foramen  lacerum  poste- 
rius, it  lies  in  contact  with  the  ganglionic  enlargement  of  the  pneumogastric,  and  is  con- 
nected with  the  ganglion  by  very  delicate  filaments,  but  it  neither  assists  in  the  forma- 
tion of  that  enlargement,  nor  is  blended  with  it :  at  its  exit  from  the  foramen  it  divides 
into  two  branches  of  equal  size ;  an  internal  or  anastomotic,  which  remains  in  contact 
with  the  pneumogastric,  and  is  distributed  with  it,  and  a  muscular  branch*  (cut  off  in 
%.  301). 

The  Anastomotic  Branch. — So  intimately  are  the  spinal  accessory  and  pneumogastric 
nerves  connected,  or,  as  it  -were,  fused  together,  that,  up  to  the  time  of  Willis,  they  were 

"  It  is  well  to  observe,  that  as  they  are  passing  through  the  foramen  lacerum  posterius,  the  pneumogastric 
and  spinal  accessory  nerves  adhere  to  the  dura  mater,  in  the  iame  manner  as  the  Gasserian  ganglion. 

5  P 


850  NEUROLOGY. 

regarded  as  a  single  nerve.  Willis  first  described  the  former,  perhaps  erroneou§^^,  as  a 
separate  nerve,  under  the  name  of  nervus  accessorius  ad  par  vagum,  sive  nerviis  spinalis. 
In  an  excellent  thesis,  published  in  1822,*  M.  Bischoff  endeavoured  to  prove  that  the 
pneumogastric  or  par  vagum  and  spinal  accessory  form  but  a  single  nerve,  analogous  to 
the  spinal  nerves  in  every  respect ;  the  spihal  accessory  being  the  nerve  of  motion,  and 
the  par  vagum  the  nerve  of  sensation :  "  Nervus  accessorius  Willisii  est  nervus  moto- 
rius,  atque  eandem  habet  rationera  ad  nervum  vagum  quam  antica  radix  nervi  spinalis 
ad  posticam.  Omnis  motio  cui  vagus  praeesse  videtur,  ab  ilia  portione  accessorii  quae 
ad  vagum  accidit,  efEcitur.  Itaque  vox  quoque,  sive  musculorum  laryngis  et  glottidis 
motus,  ab  accessorio  pendet,  et  eo  nomine  accessorius  nervus  vocalis  vocari  potest." 

To  this  view  there  are  serious  objections :  in  the  first  place,  it  is  opposed  to  the  law 
that  the  anterior  roots  preside  over  motion  and  the  posterior  over  sensation  ;  for  the 
filaments  of  origin  of  the  spinal  accessory  evidently  form  part  of  the  posterior  roots. 
Again,  how  can  it  be  supposed  that  two  nerves,  which,  like  the  spinal  accessory  and 
pneumogastric,  arise  so  distinctly  from  the  same  line,  that  it  is  often  difficult  to  separate 
them,  can  have  such  opposite  functions  ! 

Must  we  suppose  that  the  law  which  regulates  the  anterior  and  posterior  roots  of  the 
spinal  nerves  ceases  to  operate  at  the  medulla  oblongata  1  or  must  we  admit,  with  Ar- 
nold, that  there  is  not  only  a  decussation  of  fibres  from  side  to  side  in  the  medulla  ob- 
longata, but  also  from  before  backward,  so  that  the  posterior  columns  of  the  medulla  ob- 
longata become  the  motor  and  the  anterior  the  sensory  1  Still,  even  with  this  hypothe- 
sis, it  must  be  remembered  that  the  spinal  accessory  arises  in  part  below  the  point  where 
this  antero-posterior  decussation  is  supposed  to  exist.  There  evidently  is  an  antero- 
posterior decussation  opposite  to  the  two  anterior  pyramids,  as  I  have  elsewhere  stated 
(see  Medulla  Oblongata),  but  the  other  columns  of  the  spinal  cord  are  not  concerned  in  it. 

However  this  may  be,  the  anastomotic  branch  of  the  spinal  accessory  may  be  traced, 
after  maceration  in  dilute  nitric  acid,  along  the  outer  side  of  the  pneumogastric.  In  a 
great  number  of  cases,  it  evidently  gives  off  the  small  pharyngeal  nerve,  which  sometimes 
arises  exclusively  from  the  pneumogastric,  and  sometimes  from  both  the  pneumogastric 
and  the  spinal  accessory.  Scarpa  declares  the  last  arrangement  to  be  constant  and 
normal,  and  has  represented  it  in  several  figures.  In  some  subjects,  the  spinal  accessory 
appears  to  have  no  share  in  the  pharyngeal  nerve,  but  then  its  anastomotic  branch  be- 
comes applied  to  the  pneumogastric  below  the  origin  of  the  pharyngeal  nerve. 

The  anastomotic  branch  appears  to  me  to  have  no  share  in  the  formation  of  the  supe- 
rior laryngeal  nerve  ;  and  the  same  is  the  case  with  regard  to  the  recurrent  nerve.  It 
appears  to  me  anatomically  impossible  to  prove  the  continuity  of  the  spinal  accessory 
and  the  superior  and  recurrent  laryngeal  nerves  ;  I  cannot,  therefore,  admit  that  the  spi- 
nal accessory  supplies  the  intrinsic  muscles  of  the  larynx. 

The  spinal  accessory  generally  gives  off  a  number  of  twigs,  which  unite  in  front  of  the 
reddish,  and,  as  it  were,  ganglionic  trunk  of  the  pneumogastric  nerve,  to  form  a  small 
plexus,  which  adheres  to  that  nerve,  and  ends  in  the  hypo-glossal  nerve. 

Lastly,  there  are  so  many  varieties  in  the  mode  of  communication  between  the  pneu- 
mogastric and  spinal  accessory  nerves,  that  it  is  extremely  difficult  to  refer  them  to  any 
general  law. 

The  Muscular  Branch. — This  nerve  descends  vertically  between  the  internal  jugular 
vein  and  the  occipital  artery,  beneath  the  digastric  and  stylo-hyoid  muscles ;  it  runs  back- 
ward and  outward  {t,  figs.  285,  298),  beneath  the  sterno-mastoid,  generally  perforating 
that  muscle,  but  sometimes  merely  running  along  its  deep  surface,  passes  obliquely 
across  the  supra-clavicular  triangle,  and  terminates  in  the  deep  surface  of  the  trapezius. 

While  perforating  the  sterno-mastoid,  the  spinal  accessory  nerve  gives  several  branches 
to  that  muscle,  which  anastomose  with  others  from  the  third  cervicd  nerve,  and  form  a 
sort  of  plexus  within  the  muscle. 

On  emerging,  somewhat  reduced  in  size,  from  the  sterno-mastoid,  it  receives  a  branch 
{v,  fig.  298)  from  the  anastomosis,  between  the  second  and  third  cervical  nerves,  by  which 
its  size  is  greatly  increased :  it  assists  in  the  formation  of  the  cervical  plexus,  and  some- 
times of  the  posterior  auricular  nerve. 

Having  reached  the  anterior  surface  of  the  trapezius,  it  receives  two  considerable 
branches,  derived  from  the  third,  fourth,  and  fifth  cervical  nerves,  which  appear  to  me 
to  re-enforce  it.  It  gives  off  ascending  filaments  to  the  occipital  portion  of  the  muscle  ; 
and  descending  filaments,  which  continue  in  the  original  course  of  the  nerve  in  front  of 
the  muscle,  approach  its  scapular  attachments,  and  may  be  traced  down  to  its  inferior 
angle.  The  muscular  branch  of  the  spinal  accessory  belongs  exclusively  to  the  sterno- 
mastoid  and  trapezius  muscles.  It  has  been  incorrectly  stated  that  it  supplies  other  mus- 
■des,  such  as  the  rhomboidei,  the  levator  anguli  scapulae,  the  complexus,  the  splenius, 
and  the  sub-scapularis,  and  that  it  is  also  distributed  to  the  skin. 

In  front  of,  or,  rather,  in  the  substance  of  the  trapezius,  the  spinal  accessory  anasto- 
fjoaoses  with  the  posterior  branches  of  the  spined  nerves. 

*  Ne-vi  Accessorii  Willisii  Anatomia  etPhysiologia.    Bischoff.    Darmstadii. 


THE    HYPO-GLOSSAL    NERVE.  851 

Summary. — ^The  spinal  accessory  gives  branches  to  the  stemo-mastoid,  the  trapezius, 
and  the  phar)Ttx ;  it  is  believed  also  to  send  some  to  the  larynx  by  means  of  its  anasto- 
motic branch  with  the  pneumogastric.  It  communicates  with  the  second,  third,  fourth, 
and  fifth  cervical  nerves. 

Function. — In  reference  to  its  muscular  branch,  Sir  C.  Bell  has  classed  the  spinal  ac- 
cessory among  the  respiratory  nerves,  under  the  name  of  the  superior  respiratory  nerve  of 
the  trunk ;  for,  according  to  that  anatomist,  it  arises  from  the  lateral  column  of  the  cord, 
between  the  anterior  and  posterior  columns. 

With  regard  to  the  anastomotic  branch  of  this  nerve,  which  becomes  blended  with  the 
par  vagum,  M.  BischofT  lays  down  the  following  proposition  (page  95) :  "  Nervum  acces- 
sorium  nimirum  nervum  motorium  esse,  ideoque  in  partes  vagi  adscisci,  ut  motus,  qui- 
bus  hie  qui  sensificus  tantummodo  nervus  est,  praeesse  videatur,  ipse  perficiat :  eundem 
ergo  praeesse  motibus  quoque  musculorum  laryngis,  indeque  nerviun  esse  vocalem.". 
This  idea,  which  was  suggested  to  him  by  theory,  he  endeavoured  to  confirm  by  experi- 
ment. The  section  of  all  the  roots  of  the  spinal  accessory  proved  to  be  very  difficult ; 
but,  after  many  fruitless  attempts,  he  at  length  succeeded  in  dividing  them  on  both 
sides.  The  hoarseness  produced  by  section  of  all  the  roots  of  the  right  side  gradually 
increased  as  he  divided  those  of  the  left  side,  and  when  all  had  been  cut,  the  natural 
voice  of  the  animal  was  changed  to  a  very  hoarse  sound,  which  could  not  be  called  the 
voice. 

I  have  already  said  that  anatomy  affords  no  proof  that  the  laryngeal  nerves  are  derived 
from  the  spinal  accessory ;  nor  does  it  show  that  the  muscular  fibres  of  the  bronchi, 
oesophagus,  and  stomach,  receive  their  filaments  from  it. 

The  Ninth  Pair,  ok  Hypo-glossal  Nerves. 

The  hypo-glossal,  or  great  hypo-glossal  nerve,  the  ninth  cranial,  or  the  twelfth  nerve 
of  some  modem  authors,  arises  on  each  side  from  the  furrow  between  the  olivary  and 
pyramidal  bodies,  by  a  row  of  filaments  collected  into  two  very  distinct  fasciculi,  which 
proceed  to  the  anterior  condyloid  foramen  (q,  fig.  296),  perforate  the  dura  mater  separ- 
ately, and  join  together  so  as  to  emerge  from  the  canal  in  the  form  of  a  rounded  cord.* 

After  leaving  the  anterior  condyloid  canal,  the  hypo-glossal  nerve  (d,  fig.  301)  descends 
vertically  between  the  internal  carotid,  which  is  on  its  inner  side,  and  the  internal  jugu- 
lar on  its  outer  side.  At  first  it  lies  behind  the  pneumogastric  (8  to  p) ;  it  then  crosses 
very  obliquely  over  the  outer  side,  and  lower  down  it  gets  in  front  of  that  nerve,  around 
which,  therefore,  it  describes  a  semi-spiral. 

Having  arrived  below  the  posterior  belly  of  the  digastric  muscle,  the  hypo-glossal 
changes  its  direction  and  runs  forward  and  downward  {d,  fig.  300),  crossing  in  front  of 
the  internal  and  external  carotids  [and  hooking  beneath  the  occipital  artery] ;  it  is  then 
reflected  upward  to  reach  the  under  surface  of  the  tongue  {d,  near  x),  and  thus  describes 
a  loop  having  the  concavity  turned  upward,  parallel  to  and  below  the  digastricus,  and 
almost  ten  lines  above  the  os  hyoides. 

Relations. — It  is  situated  deeply  in  its  vertical  portion,  where  it  runs  along  the  verte- 
bral column,  becomes  superficial  in  its  middle  portion  (d,  fig.  298),  where  it  is  merely 
separated  from  the  skin  by  the  platysma  and  the  prominence  of  the  sterno-mastoid,  and 
again  becomes  deep-seated  anteriorly,  where  it  rests  on  the  hyo-glossus  muscle,  and  is 
covered  by  the  anterior  belly  of  the  digastricus  and  by  the  stylo-hyoideus,  and  then  by 
the  sub-maxillary  gland  and  the  mylo-hyoideus,  after  which  it  enters  the  genio-glossus, 
and  is  lost  in  the  substance  of  the  tongue. 

The  relations  of  the  hypo-glossal  nerve  and  the  lingual  artery  are  worthy  of  remark. 
The  nerve  is  at  first  parallel  to  and  above  the  artery,  is  soon  separated  from  it  by  the 
hyo-glossus,  and  then  rejoins  it  in  front  of  that  muscle.  In  the  substance  of  the  tongue, 
the  artery  lies  to  the  outer  side  of  the  genio-glossus,  while  the  nerve  runs  forward 
through  the  fibres  of  the  muscle. 

The  Collateral  Branches  of  the  Hypo-glossal  Nerve. 

Some  of  these  are  anastomotic.  Thus,  as  it  crosses  the  three  divisions  of  the  eighth 
nerve,  the  hypo-glossal  lies  in  contact  with  the  pneumogastric  nerve,  with  which  it 
sometimes  communicates  by  very  delicate  filaments.  Most  commonly  the  anastomosis 
between  these  two  nerves  forms  a  true  plexus,  t  This  communication  is  sometimes 
eftected  with  the  anastomotic  branch  of  the  spinal  accessory,  sometimes  with  the  pneu- 
mogastric itself 

The  hypo-glossal  is  also  connected  by  a  very  small  anastomotic  twig  to  the  superior 
cervical  ganglion. 

It  also  receives  three  filaments  from  the  nervous  loop  formed  by  the  union  of  the  first 
and  second  cervical  nerves,  namely,  two  from  the  first  nerve  and  one  from  the  second. 
The  superior  filament  from  the  first  nerve  ascends,  an  arrangement  which  it  is  difficult 
to  understand,  for  it  passes  in  a  direction  towards  the  roots  of  the  hypo-glossal ;  if  it  be 

*  The  vertebral  artery  is  situated  in  front  nf  the  filaments  of  the  hypo-glossal. 

t  [In  connexion  with  this  fact,  it  may  be  observed  that  the  descendens  noni  (a  branch  of  the  hypo-|floaaal 
ttBr\-ol  sometimes  arises  in  part  or  entirely  from  the  pneumogastric,  lower  down  in  the  neck.] 


85S  NEUROLOGY. 

supposed  that  this  filament  is  derived  from  the  hypo-glossal,  then  it  is  directed  towards 
the  roots  of  the  first  cervical  nerve. 

Opposite  to  the  anterior  border  of  the  hyo-glossus  it  gives  off  a  very  remarkable  anas- 
tomotic branch,  which  forms  an  arch  with  the  lingual  nerve. 

The  other  collateral  branches  which  it  gives  off  are  the  descending  branch ;  a  small 
muscular  infra-hyoid  branch ;  and  the  branches  for  the  hyo-glossvs  and  stylo- glossus. 

The  descending  branch  {ramus  descendens  noni,  h,figs.  298, 300,  301).  This  is  the  most 
remarkable  branch  of  the  hypo-glossal  nerve.*  It  comes  off  at  the  point  where  the 
nerve  changes  its  direction,  descends  vertically  in  front  of  the  internal  carotid  and  then 
of  the  common  carotid,  curves  outward,  and  anastomoses  upon  the  internal  jugular  vein 
with  the  descending  branch  of  the  cervical  plexus  {z,fig.  298),  so  as  to  form  a  loop,  hav- 
ing its  concavity  turned  upward.  From  the  convexity  of  this  loop  two  branches  proceed, 
.of  which  one  is  distributed  to  the  omo-hyoid,  while  the  other  (5^)  divides  into  two  twigs, 
one  of  which  enters  the  outer  border  of  the  stemo-hyoid,  while  the  other  penetrates  the 
deep  surface  of  the  sterno-thyroid  muscle.  I  have  seen  one  of  these  branches  come  di- 
rectly from  the  hypo-glossal. t 

It  is  equally  important  to  study  both  the  mode  of  origin  and  anastomosis  of  the  de- 
scending branch  of  the  ninth  ner^'e.t  The  origin  of  this  branch  is,  in  fact,  almost  en- 
tirely from  the  anastomotic  branches  of  the  first  and  second  cervical  nerves,  which,  after 
having  been  in  contact  with  the  hypo-glossal,  are  given  off  from  it  to  constitute  the  de- 
scending branch.  This  arrangement  is  especially  evident  in  preparations  that  have  been 
macerated  in  diluted  nitric  acid.  I  should  state,  however,  that  it  is  not  equally  evident 
in  all  subjects ;  and  that  some  filaments,  derived  from  the  hypo-glossal  itself,  always  join 
those  from  the  cervical  nerves.  It  has  appeared  to  me  that  the  most  internal  of  the  fila- 
ments derived  from  the  hypo-glossal  nerve  itself  followed  a  retrograde  course  ;  that  is  to 
say,  that  it  ran  from  below  upward,  as  if  it  arose  at  the  terminal  extremity  of  the  hyi^o- 
glossal,  and  then  left  that  nerve  to  join  the  descendens  noni  at  the  point  where  that 
branch  is  given  off. 

The  branches  from  the  first  and  second  cervical  nerves  to  the  hypo-glossal  should  be 
regarded  as  late  origins  of  that  nerve,  which  is  sensibly  increased  in  size  after  being 
joined  by  them.  I  have  seen  the  third  and  even  the  fourth  cervical  nerve  assist  in  the 
formation  of  the  descendens  noni ;  the  branch  from  the  fourth  nerve  arose  partly  from 
the  phrenic. 

The  mode  of  anastomosis  of  the  descendens  noni  with  the  descending  branch  of  the 
cervical  plexus,  or,  rather,  of  the  third  cranial  nerve,  is  subject  to  much  variety. 

The  following  is  the  most  frequent  arrangement : 

All  the  filaments  composing  these  two  descending  branches  unite  together,  with  the 
exception  of  the  uppermost  filament,  which  describes  a  loop  having  its  concavity  turned 
upward,  and  resembhng  a  vascular  anastomosis  :  so  that,  if  we  suppose  it  to  be  derived 
from  the  loop  of  the  Kypo-glossal,  it  would  be  directed  towards  the  origin  of  the  cervical 
nerves  ;  and  if,  on  the  contrary,  we  suppose  it  to  arise  from  the  cervical  nerves,  it  would 
be  directed  towards  the  origin  of  the  hypo-glossal.  This  arrangement,  which  I  have  had 
the  opportunity  of  observing  in  many  parts  of  the  nervous  system,  appears  to  me  to  con- 
stitute a  mode  of  anastomosis  well  worthy  the  attention  of  physiologists.  I  am  induced 
to  regard  it  as  intended  to  establish  connexions  between  the  different  points  of  the  spinal 
cord.^ 

*  See  note,  last  page. 

t  [Another  branch  is  described  and  figured  by  Arnold  as  descending  in  front  of  tlie  vessels,  and  joining  the 
cardiac  nerves  in  the  thorax.] 

X  There  are  certain  cases  in  which  the  descendens  noni  is  analyzed  by  nature  ;  namely,  when  the  branch 
from  the  second  cervical  nerve  is  not  applied  to  the  hypo-glossal,  but  remains  at  a  distance  from  it.  In  this 
case,  the  filaments  derived  from  the  hypo-glossal  join  themselves  to  this  branch  ;  one  of  them  ascends  towards 
the  origin  of  the  second  cervical  nerve,  and  the  others  proceed  towards  its  termination.  In  one  case,  the  hypo- 
glossal gave  a  very  small  twig  to  the  first  cervical  nerve,  before  receiving  its  accustomed  branch  from  that 
nerve  ;  the  descending  branch  from  the  cervical  plexus  was  replaced  by  tEree  branches  derived  from  the  first, 
second,  third,  and  fourth  cervical  nerves,  which  formed,  together  with  the  descendens  noni  and  its  branches,  a 
succession  of  loops,  in  front  of  the  external  and  common  carotids.  In  another  case,  the  three  superior  cervical 
nerves  assisted  in  forming  the  descendens  noni.  The  following  is  a  detailed  description  of  that  case,  which 
throws  considerable  light  upon  the  connexions  between  the  hypo-glossal  and  cervical  nerves.  One  large  branib 
proceeded  from  the  anastomotic  arch  of  the  first  and  second  cervical  nerves  ;  this  large  branch,  as  soon  as  't 
reached  the  hypo-glossal  nerve,  divided  into  three  filaments  of  unequal  size  :  an  ascending,  which  was  directed 
towards  the  origin  of  the  hypo-glossal  nerve  ;  a  middle,  which  became  blended  with  that  nerve  ;  and  a  descend- 
ing, which  was  the  largest,  and  which  merely  ran  along  in  contact  with  the  same  nerve.  At  the  point  where 
this  last-named  filament  left  the  hypo-glossal  to  form  the  descendens  noni,  it  evidently  received  a  twig  from 
the  hypo-glossal  itself,  which  came  from  the  lower  part  of  that  nerve,  and  was  reflected  upon  the  descendens 
noni  in  a  retrograde  manner,  so  that  this  twig,  derived  from  the  hypo-glossal,  had  one  end  at  the  terminal  ex- 
tremity of  that  nerve,  i.  e.,  in  the  muscles  of  the  tongue,  and  the  other  end  in  the  muscles  of  the  infra-hyoid 
region.  In  this  same  case,  the  descending  branch  of  the  second  cervical  nerve  divided  into  three  filaments, 
one  of  which  joined  the  hypo-glossal  nerve,  another  formed  an  anastomotic  arch  with  the  third  cervical  nerve, 
while  the  third  filament  passed  downward  to  assist  m  forming  the  descending  branch  of  the  cervical  plexus. 
Lastly,  the  third  cervical  nerve  in  this  case  gave  off  an  ascending  branch,  which  anastomosed  with  the  seo(md, 
and  a  descending  branch,  which  assisted  in  forming  the  descending  branch  of  the  cenical  plexus  ;  there  were 
therefore  two  loops  or  arches,  one  internal  and  the  other  external ;  they  were  situated  opposite  to  the  bifurca- 
tion of  the  common  carotid  artery. 

i,  This  mode  of  anastomosis  may,  perhaps,  have  some  relation  to  that  reflex  action  of  the  spinal  cord,  which 


GENERAL    VIEW   QF    THE    CRANIAL    NERVES,  853 

The  Small  Muscular  Branch  of  the  Infra-hyoid  Region. — This  nerve  comes  off  at  the 
posterior  border  of  the  hyo-glossus,  and  ramifies  in  the  upper  part  of  the  muscles  of  the 
infra-hyoid  region ;  a  small  transverse  filament  runs  along  the  hyoid  attachments  of  these 
muscles.    This  small  nerve  may  be  regarded  as  an  accessory  to  the  descendens  noni. 

'The  Branches  for  the  Hyo-glossus  and  Stylo-glossus. — As  the  hypo-glossal  nerve  comes 
into  contact  with  the  hyo-glossus,  it  becomes  flattened  and  widened,  and  gives  off  sev- 
eral ascending  branches,  most  of  which  ramify  in  the  hyo-glossus,  though  several  end  in 
the  stylo-glossus. 

The  Terminal  Branches  of  the  Hypo-glossal  Nerve. 

Opposite  to  the  anterior  border  of  the  hyo-glossus  the  hypo-glossal  nerve  gives  off 
some  twigs  to  the  under  surface  of  the  genio-hyoideus ;  it  then  enters  the  genio-hyo- 
glossus,  and  expands  (d,  near  x,  fig.  300)  into  a  great  number  of  filaments,  which  run  for- 
ward, perforate  that  muscle  at  successive  points,  and  are  lost  in  the  substance  of  the 
tongue.  It  is  impossible  to  follow  these  filaments  to  the  papillary  membrane  of  the 
tongue.  Some  of  them  anastomose  with  the  lingual  («)  nerve,  a  branch  of  the  inferior 
maxillary  division  of  the  fifth ;  several  accompany  the  lingual  artery. 

The  relations  of  the  lingual  portions  of  the  hypo-glossal  nerve  with  the  lingual  of  the 
fifth  are  worthy  of  attention.  The  lingual  nerve  occupies  the  under  part  of  the  border 
of  the  tongue,  runs  along  the  stylo-glossus,  and  may  be  traced  as  far  as  the  apex  of  the 
organ  :  it  is  sub-mucous  in  the  whole  of  its  extent.  The  hypo-glossal  nerve  is  situated 
on  a  much  lower  plane,  and  occupies  the  under  surface  of  the  tongue,  on  each  side  of 
the  median  Une. 

Function. — The  hypo-glossal  is  a  muscular  nerve  :  it  regulates  the  movements  of  the 
tongue,  while  the  lingual  of  the  fifth  and  the  glosso-pharyngeal  confer  sensibility  upon  it. 
This  fact  is  most  clearly  established  by  anatomical,  physiological,  and  pathological  ob- 
servations. Like  all  nerves  having  a  simple  distribution,  the  hypo-glossal  has  not  a 
plexiform  structure. 

General  View  of  the  Cranial  Nerves. 

All  the  spinal  nerves  present  the  greatest  regularity  in  arising  from  two  series  of  roots, 
in  having  a  ganglionic  enlargement  on  their  posterior  roots,  and  even  in  their  course 
and  termination,  the  differences  or  modifications  of  which  depend  on  the  different  struc- 
ture of  the  parts  to  which  they  are  distributed  ;  but  the  greatest  irregularity  appears  to 
prevail  in  reference  to  the  origin,  the  course,  and  the  termination  of  the  cranial  nerves. 
From  the  comparison  which  has  been  made  between  the  scull  and  the  vertebrae,  and 
from  the  possibility  of  resolving  the  bones  of  the  cranium  into  a  certain  number  of  cra- 
nial vertebrae,  anatomists  have  entertained  the  idea  of  drawing  a  parallel  between  the 
cranial  and  the  spinal  nerves.  It  has  been  conceived  that  the  number  of  cranial  nerves 
ought  to  be  regulated  by  the  number  of  cranial  vertebras  admitted  by  different  anato- 
mists ;  and,  moreover,  that  in  order  to  draw  a  fair  comparison  between  these  two  sets 
of  nerves,  the  special  nerves  of  the  face,  namely,  the  olfactory,  the  optic,  and  the  auditory 
nerves,  should  be  entirely  disregarded. 

Now  we  have  already  shown  (see  Osteology)  that  there  are  three  cranial  vertebrae, 
between  which  there  are  two  inter- vertebral  foramina ;  that  the  anterior  inter-vertebral 
foramen  is  represented  by  the  sphenoidal  fissure,  to  which  we  must  annex  the  foramen 
rotundum  and  the  foramen  ovale ;  and  that  the  posterior  inter- vertebral  foramen  is  rep- 
resented by  the  foramen  lacerum  posterius,  together  with  the  anterior  condyloid  foramen. 

This  being  premised,  we  shall  admit  two  pairs  of  cranial  nerves,  an  anterior  and  a 
posterior. 

The  posterior  cranial  pair  consists  on  each  side  of  the  eighth  and  ninth  nerves,  namely, 
of  the  pneumogastric,  glosso-pharyngeal,  spinal  accessory,  and  hypo-glossal  nerves. 
The  pneumogastric  and  the  glosso-pharyngeal,  each  of  which  has  a  ganglion  analogous  to 
the  inter- vertebral  ganglia,  represent  the  posterior  roots  of  a  spinal  nerve,  while  the  spi- 
nal accessory  and  the  hypo-glossal,  which  have  no  ganglion,  represent  the  anterior  root. 
The  two  last-named  nerves  are  exclusively  motor,  while  the  pneumogastric  and  the 
glosso-pharyngeal  appear  to  me  to  be  mixed  nerves,  that  is,  both  sensory  and  motor. 

The  anterior  cranial  pair  is  composed  on  each  side  of  the  fifth  nerve,  the  ganglion  of 
which  is  quite  analogous  to  the  inter- vertebral  ganglia,  and  the  large  portion  of  the  root 
of  which  accurately  represents  the  posterior  root  of  a  spinal  nerve  ;  and  of  the  third  or 
conmion  motor  nerve  of  the  eye,  of  the  fourth  or  pathetic  nerve,  of  the  sixth  or  exter  • 
nal  motor  nerve  of  the  eye,  of  the  portio  dura  of  the  seventh,  and,  lastly,  of  the  non- 
ganglionic  portion  of  the  fifth.  All  these  last-named  nerves  are  the  nerves  of  motion  ; 
while  the  ganglionic  portion  of  the  fifth  is  the  nerve  of  sensation. 

Moreover,  as  the  spinal  nerves  communicate  with  the  ganglia  of  the  great  s3Tnpa- 
thetic,  it  is  of  importance,  for  the  completion  of  our  comparison,  to  determine  the  com- 
munications of  the  two  cranial  pairs  of  nerves  with  the  same  system  of  ganglia.     Now 

Dr.  Marshall  Hall  believes  to  be  the  cause  of  certain  instinctive  motions.     ("  On  the  Reflex  Functions  of  the 
.Medulla  Oblongata  and  MeduUa  Spinalis."— PAtZ.  Trans..  1833.) 


854  NEUROLOGY. 

I  regard  the  superior  cervical  ganglion  of  the  great  sympathetic  as  common  to  the  ivm 
supposed  cranial  pairs  and  to  the  three  superior  cervical  pairs  ;  in  fact,  the  superior  cer 
vical  ganglion  communicates  with  all  the  branches  of  the  posterior  cranial  pair,  except- 
ing the  spinal  accessory,  viz.,  with  the  pneumogastric,  the  glosso-pharyngeal,  and  the 
hypo-glossal ;  and  it  also  communicates  with  the  anterior  cranial  pair,  and  more  partic- 
ularly with  the  fifth  and  sixth  nerves. 

As  to  the  ophthalmic,  spheno-palatine,  otic,  and  sub-maxillary  ganglia,  which  Arnold 
regards  as  annexed  to  the  organs  of  the  senses,  viz.,  the  ophthalmic  to  the  eye,  the 
spheno-palatine  to  the  nose,  the  otic  to  the  ear,  and  the  sub-maxillary  to  the  organ  of 
taste,  and  which  Bichat  described  as  the  cephalic  portion  of  the  great  sympathetic,  [  am 
of  opinion  that  they  are  mere  local  ganglia,  which  do  not  form  part  of  the  general  sym- 
pathetic system  :  besides,  the  ophthalmic  and  the  otic  ganglion  only  can  be  shown  to  be 
connected  with  the  organs  of  any  sense  :  it  is  impossible  to  show  that  the  spheno-pala- 
tine ganglion,  the  very  existence  of  which  as  a  ganglion  is  often  doubtful,  has  any  con- 
nexions with  the  organ  of  smell,  or  that  the  sub-maxillary  ganglion,  which  is  much 
more  closely  connected  with  the  sub-lingual  gland,  has  any  relations  with  the  organ  of 
taste. 


THE  SYMPATHETIC  SYSTEM  OF  NERVES. 
General  Remarks. — The  Cervical  Portion  of  the  Sympathetic. — The  Superior  Cervical  Gan- 
glion— its  Superior  Branch,  Carotid  Plexus,  and  Cavernous  Plexus — its  Anterior,  Exter- 
nal, Inferior,  and  Internal  Branches. — The  Middle  Cervical  Ganglion. — The  Inferior  Cer- 
vical Ganglion. — The  Vertebral  Plexus. — The  Cardiac  Nerves  :  Right,  Superior,  Middle, 
and  Inferior,  Left. — The  Cardiac  Ganglion  and  Plexuses. — The  Thoracic  Portion  of  the 
Sympathetic. — The  External  and  Internal  Branches. — The  Splanchnic  Nerves,  Great  and 
Small. — The  Visceral  Ganglia  and  Plexuses  in  the  Abdomen,  viz.,  the  Solar  Plexus  and 
Semilunar  Ganglia. — The  Diaphragmatic  and  Supra-renal ;   the  Coeliac,  the  Superior 
Mesenteric,  the  Inferior  Mesenteric,  and  the  Renal,  Spermatic,  and  Ovarian  Plexuses. — 
The  Lumbar  Portion  of  the  Sympathetic. — The  Communicating,  External,  and  Internal 
Branches. — The  Lumbar  Splanchnic  Nerves  and  Visceral  Plexuses  in  the  Pelvis. — The 
Sacral  Portion  of  the  Sympathetic. — General  View  of  the  Sympathetic  System. 
We  have  seen  that  the  nerves  arising  from  the  cerebro-spinal  axis  are  distributed  to 
the  organs  of  the  senses,  to  the  skin,  to  the  muscles,  in  short,  to  all  the  organs  of  ani- 
mal life.    The  pneumogastric  nerve  alone  is  distributed  to  the  organs  of  respiration,  and 
the  upper  part  of  the  alimentary  canal,  viz.,  the  pharynx,  the  oesophagus,  and  the  stom- 
ach.    We  shall  now  see  that  all  the  internal  organs,  which  are  beyond  tlie  influence  of 
volition  and  consciousness,  are  provided  with  a  special  nervous  apparatus,  which  is  call- 
ed the  great  sympathetic,  the  sympathetic  system,  the  ganglionic  system,  or  the  nervous  sys- 
tem of  organic  or  nutritive  life. 

The  sympathetic  system  consists  of  two  long,  knotted  cords  (/to  v,fig.  268,  in  which 
figure  these  cords  are  represented  as  if  drawn  outward  away  from  their  natural  position) 
extended  one  on  each  side  of  the  vertebral  column,  from  the  first  cervical  to  the  last 
sacral  vertebra ;  these  cords  are  enlarged  opposite  each  vertebra,  to  form  a  series  of 
ganglia,  which  communicate  with  all  the  spinal  and  cranial  nerves  on  the  one  hand,  and 
give  off  all  the  visceral  branches  on  the  other.  The  sympathetic  system  consists  es- 
sentially of  two  distinct  parts  :  of  a  central  portion,  formed  by  the  two  cords  ;  and  of  a 
visceral,  median,  or  prevertebral  portion,  consisting  of  certain  plexuses  and  ganglia,  which 
communicate  with  the  central  cords,  surround  the  arteries  as  if  in  sheaths,  penetrate 
the  viscera  with  them,  and  establish  a  communication  between  the  sympathetic  cords 
of  the  right  and  left  sides.  We  cannot  pay  too  much  attention  to  the  connexion  be- 
tween the  ganglionic  nerves  and  the  arteries,  which  always  serve  as  a  support  for  these 
nerves,  and  for  which,  according  to  some  anatomists,  the  nerves  are  exclusively  des- 
tined. 

Each  half  of  the  sympathetic  system  may  be  described  in  two  ways  :  either  as  a  con- 
tinuous cord,  having  ganglia  at  intervals  upon  it,  or  as  a  series  of  ganglia  or  centres, 
which  may  first  be  examined  independently  of  each  other,  and  around  which  all  the  fila- 
ments that  enter  or  emerge  from  them  may  then  be  arranged. 

The  first  method,  which  is  the  more  natural  one,  was  adopted  by  the  older  anato- 
mists, who  described  the  sympathetic  in  the  same  way  as  other  nerves ;  according  to 
the  second  method,  which  is  the  one  adopted  by  Bichat,  all  the  ganglia,  whatever  situa- 
tion they  may  occupy,  are  included  in  the  sympathetic  system ;  the  ophthalmic,  the 
spheno-palatine,  and  other  cranial  ganglia  would,  according  to  this  view,  be  comprised 
in  the  sympathetic  system. 

I  believe  that  the  better  mode  of  description  is  one  which  associates  the  idea  of  a 
centre  with  that  of  a  cord.  In  fact,  as  the  sympathetic  system  consists  of  a  double  line, 
it  is  natural  to  describe  it  as  a  nervous  cord,  having  two  extremities,  one  cephalic,  the 
other  pelvic  ;  and  as  each  ganglion  forms  the  point  of  termination  or  of  origin  to  a  great 


THE    SUPERIOR   CERVICAL   GANGLION. 


856 


number  of  nervous  filaments,  these  bodies  may  very  properly  be  regarded  as  central 
points.  The  visceral  portion  of  the  sympathetic  nerves  will  be  described  with  the  gan- 
glia to  which  they  are  connected.  * 

I  shall  describe  in  succession  the  cervical,  the  thoracic,  the  abdominal,  and  the  pelvic 
portion  of  the  s}aTipathetic.  I  have  already  said  that  I  do  not  recognise  any  proper  ce- 
phalic portion  of  this  system  of  nerves,  for  the  ophthalmic  and  the  other  cranial  ganglia 
seem  to  me  to  belong  to  a  totally  different  class 

The  Cervical  PortioiWf  the  Sympathetic  System. 
The  cerw:a„  portion  of  the  sympathetic  {ft,  fig-  302)  has  this  peculiarity,  that,  instead 
of  being  composed  of  as  many  ganglia  as  there  are  j?i^.  302. 

vertebrae,  it  has  only  two  or  three.  This  may  be 
explained  by  supposing  that  the  superior  cervical 
ganglion  represents  by  itself  the  ganglia  which  are 
wanting.  It  will  hereafter  be  seen  that  the  lumbar 
ganglia  are  rather  frequently  fused  in  a  similar  man- 
ner. The  cervical  portion  of  the  sympathetic  is 
situated  on  the  anterior  region  of  the  vertebral  col- 
umn, behind  the  internal  and  common  carotid  ar- 
teries, the  internal  jugular  vein,  and  the  pneumo- 
gastric  nerve  (p).  It  is  connected  to  all  these  parts, 
and  to  the  praevertebral  muscles,  by  some  very 
loose  cellular  tissue,  a  layer  of  fascia  intervening 
between  them  ;  it  commences  by  a  large  fusiform 
ganglion,  the  superior  cervical  ganglion  (/) ;  this  is 
succeeded  by  a  nervous  cord  of  variable  size,  which 
terminates  in  the  middle  cervical  ganglion  (a)  when 
that  exists,  but  when  it  is  absent  in  the  inferior  cer- 
vical ganglion  (t),  which  is  continuous  with  the  first 
thoracic  ganglion,  either  directly  or  through  the 
medium  of  two  or  three  very  remarkable  nervous 
loops,  or  frequently  by  both  methods  of  connexion. 
We  shall  proceed  to  examine  the  three  cervical 
ganglia. 

The  Superior  Cervical  Ganglion. 

Dissection. — Remove  the  corresponding  ramus  of 
the  lower  jaw  ;  separate  the  ganglion  very  careful- 
ly from  the  pneuraogastric,  glosso-pharyngeal,  and 
hypo-glossal  nerves,  behind  which  it  is  placed.  In 
order  to  trace  the  superior  or  carotid  branch,  make 
an  antero-posterior  median  section  of  the  head ; 
open  the  foramen  lacerum  posterius  from  behind, 
in  the  manner  indicated  for  exposing  the  pneumo- 
gastric,  and  then  examine  the  ganglion  and  its  su- 
perior branch  from  the  inner  side. 

The  superior  cervical  ganglion  (/)  is  olive-shaped 
or  fusiform :  it  is  situated  in  front  of  the  second 
and  third  cervical  vertebrae,  from  which  it  is  sep- 
arated by  the  rectus  capitis  anticus ;  it  is  behind 
the  internal  carotid  artery,  and  the  glosso-pharyn- 
geal, pneumogastric,  and  hypo-glossal  nerves  ;  its 
upper  extremity  is  about  ten  or  twelve  lines  distant 
from  the  lower  orifice  of  the  carotid  canal ;  it  is 
said  to  have  been  found  two  inches  from  it. 

It  is  larger  than  the  other  cervical  ganglia  {gan- 
glion cervicale  magnum),  but  it  varies  much  both  in 
its  length  and  its  other  dimensions  ;  thus,  its  low- 
er extremity  has  been  seen  to  reach  the  fourth, 
fifth,  and  even  the  sixth  cervical  vertebra.  Its  col- 
our is  grayish,  and  its  surface  smooth  :  not  unfre- 
quently  it  is  bifurcated  at  its  lower  extremity ;  it 
is  rather  often  double.  Lobstein  has  figured  a  case  of  this  kind  ;  and  there  were  also  two 
superior  cervical  ganglia,  one  placed  above  the  other,  in  a  case  of  hypertrophy  of  these 
ganglia,  examined  and  represented  by  myself — (Anat.  Path.,  liv.  i.,  pi.  3.) 

These  cases  of  a  double  superior  cervical  ganglion  evidently  depend  on  subdivision  ol 
the  single  ganglion  usually  existing. 

The  branches  which  end  in  or  emerge  from  the  superior  cervical  ganglion  may  be  di- 
'  vided  into  superior,  inferior,  external,  internal,  and  anterior.    I  shall  divide  them  into  those 


856  NEUROLOGY. 

which  communicate  with  the  cranial  and  cervical  nerves,  those  which  communicate 
with  the  other  cervical  ganglia,  and  into  arterial  and  visceral  branches.  The  superior 
cervical  ganglioR  also  gives  off  several  twigs  to  the  muscles  of  the  prevertebral  region. 

The  superior  cervical  ganghon  communicates  with  the  cranial  nerves  by  means  of  its 
superior  or  carotid  branch  and  its  anterior  branches.  It  communicates  with  the  cervical 
nerves  by  its  external  branches.  It  communicates  with  the  other  cervical  ganglia  by 
its  inferior  branch.  Its  visceral  and  arterial  Ranches  are  the  pharyngeal,  the  cardiac, 
and  the  branches  for  the  external  carotid,      ^j^ 

The  Superior  or  Carotid  Branch  from  the  Inferior  Cervical  Ganglion. 

The  superior  or  carotid  branch,  or  the  branch  of  communication  with  the  nerves  which 
constitute  the  anterior  cranial  pair,  has  been  for  a  long  time  regarded  as  the  origin  of 
the  sympathetic  nerve ;  and  as,  previously  to  the  time  of  Meckel,  the  anastomosis  of 
this  carotid  branch  with  the  sixth  cranial  nerve,  or  external  motor  of  the  eye,  was  the 
only  one  known,  it  was  supposed  that  the  sympathetic  arose  from  the  sixth  nerve  ;  the 
discovery  of  the  vidian  nerve  by  the  elder  Meckel  has  led  to  the  admission  of  two  ori- 
gins or  roots  of  the  sympathetic,  namely,  one  from  the  fifth  and  another  from  the  sixth 
cranial  nerve. 

Since  the  researches  of  modern  anatomists,  the  study  of  the  superior  or  carotid  branch 
of  the  superior  cervical  ganglion  has  become  one  of  the  most  complicated  points  in  the 
anatomy  of  the  nervous  system. 

This  carotid  branch  appears  to  be  a  prolongation  of  the  superior  cervical  ganglion  ;  it 
tapers  as  it  approaches  the  carotid  canal,  into  which  it  enters,  after  having  divided  into 
two  branches,  one  of  which  runs  on  the  inner  side  and  the  other  on  the  outer  side  of 
the  artery.  These  branches  communicate  with  each  other,  subdivide,  and  unite  to  form 
the  carotid  plexus,  and  having  reached  the  cavernous  sinus,  form  a  plexus,  named  the 
cavernous  plexus,  which  gives  off  the  communicating  branches  to  the  sixth  and  fifth  nerves, 
and  also  the  small  plexuses  which  surround  the  internal  carotid  and  its  branches.* 

Laumonier,  and  after  him  Lobstein  and  several  others,  described  a  ganghon,  named 
the  carotid  ganglion,  in  the  first  turn  of  the  carotid  canal ;  but  it  is  in  vain  to  search  for 
it,  unless  some  slight  enlargements  on  the  external  and  internal  branches,  wherevei 
they  give  off  or  receive  twigs,  are  to  be  regarded  as  ganglionic.  + 

During  their  course  in  the  carotid  canal,  the  external  and  internal  divisions  of  the  ca- 
rotid portion  of  the  sympathetic  give  off  the  following  branches  : 

An  Anastomotic  Twig  to  the  Nerve  of  Jacobson. — This  comes  off  from  the  external 
branch,  and  is  very  small ;  it  perforates  the  external  wall  of  the  carotid  canal,  enters 
the  cavity  of  the  tympanum,  and  anastomoses  with  the  nerve  of  Jacobson,  a  branch  of 
the  glosso-pharyngeal. 

An  Anastomotic  Twig  to  the  Spheno-palatine,  or  McekeVs  Ganglion. — This,  like  the  pre- 
ceding, comes  from  the  external  division  of  the  carotid  branch  of  the  sympathetic,  and 
passes  to  the  vidian  or  pterygoid  branch  of  the  superior  maxillary  nerve.  We  have  al- 
ready spoken  of  this  twig,  under  the  name  of  the  carotid  or  deep  branch  of  the  vidian 
nerve.  Anatomists  differ  as  to  whether  it  should  be  regarded  as  passing  from  the  fifth 
nerve  to  the  superior  cervical  ganglion,  or  from  the  superior  cervical  ganglion  to  the 
fifth  nerve.  Arnold,  on  account  of  its  grayish  colour  and  slight  consistence,  regards  it 
as  coming  from  the  superior  cervical  ganglion,  while  he  believes  the  great  superficial 
petrosal  nerve,  i.  e.,  the  cranial  branch  of  the  vidian,  also  from  its  colour  and  consist- 
ence, to  belong  to  the  cerebro-spinal  system  of  nerves,  and  to  be  a  branch  of  the  fifth 
nerve.  I  have  already  said  that  I  have  never  found  sufficient  difference  between  the 
superior  petrosal  and  carotid  branches  of  the  vidian  to  warrant  this  distinction.  These 
two  nerves  are,  moreover,  perfectly  distinct  from  each  other  as  far  as  the  spheno-pala- 
tine ganglion,  in  which  they  terminate. 

It  is  important  to  observe  that  the  two  branches  of  the  vidian  nerve  terminate  in  the 
enlargement  called  the  spheno-palatine,  or  Meckel's  ganglion :  the  connexion  of  this 
ganglion  with  the  superior  cervical  ganglion  has  not  been  overlooked  by  those  anato- 
mists who  regard  the  spheno-palatine  enlargement  as  a  ganglion,  and  who  consider  the 
cranial  ganglia  as  forming  part  of  the  sympathetic  system. 

Anastomotic  Branches  to  the  Sixth  Nerve. — Several  branches,  generally  three,  turn  round 
the  convex  side  of  the  second  curve  of  the  internal  carotid,  reach  the  outer  side  of  that 
artery,  and  anastomose,  either  separately,  or,  after  having  united  together,  with  the  sixth 
or  external  motor  oculi  nerve.  The  nerves  join  at  an  acute  angle  opening  backward, 
within  the  cavernous  sinus,  and  at  the  point  where  the  sixth  nerve  crosses  the  carotid  ; 
as  this  nerve  becomes  flattened  and  widened  opposite  to  the  artery,  it  has  been  imagined 
that  it  was  really  enlarged,  and  that  this  augmentation  was  due  to  the  addition  of  fila- 
ments from  the  sympathetic  nerve  ;  but  the  enlargement  is  only  apparent,  and,  notwith- 
standing the  difference  in  colour,  I  should  be  inclined  to  admit  that  the  communicating 

*  The  carotid  branch  is  sometimes  single,  and  turns  spirally  around  the  artery,  being:  placed  at  first  behind, 
then  on  the  outer  side,  next  on  the  inner,  and  a^ain  on  the  outer  side  of  the  vessel. 

t  Arnold,  whose  authority  upon  such  a  subject  is  of  great  weight,  has  never  seen  this  ganglion  ;  he  very 
properly  remarks,  that  even  those  anatomists  vho  admit  the  existence  of  it  aro  not  agreed  as  to  its  situation 


THE    CAVERNOUS    PLEXUS,    ETC. 

filaments  between  the  sixth  nerve  and  the  carotid  branches  of  the  sympathetic  are  fur- 
nished by  the  sixth  nerve,  and  have  a  reflected  course.  I  have  seen  the  three  commu- 
nicating filaments  between  the  upper  part  of  the  sympathetic  and  the  sixth  nerve  form 
a  ganglifonn  enlargement  as  they  were  about  to  join  the  latter ;  and  it  was  this  gangli- 
form  enlargement  which  gave  origin  to  the  plexus  surroimding  the  internal  carotid  ar- 
tery and  its  branches. 

The  Cavernous  Plexus. 

The  cavernous  plexus,  in  which  the  two  divisions  of  the  carotid  branch  of  the  superior 
cervical  ganglion  at  length  terminate,  is  situated  on  the  inner  side  of  the  carotid  artery, 
at  the  point  where  that  vessel  enters  the  cavernous  sinus.  From  this  grayish  plexus, 
which  is  intermixed  with  small  vessels  (plexus  nervoso-arteriosus,  Walter),  a  consider- 
able number  of  filaments  proceed,  some  of  which  establish  a  communication  between  it 
and  the  fifth  nerve,  while  others  surround  the  internal  carotid,  and  accompany  all  its 
ramifications.  The  following  very  numerous  branches  emerge  from  the  cavernous 
plexus  : 

Some  communicating  Filaments  to  the  Third  Nerve  or  External  Motor  Oculi,  before  the  Di- 
vision of  that  Nerve. — These  filaments  pass  above  the  sixth  nerve,  to  which  they  appear 
to  be  applied.* 

A  Filament  of  Communication  with  the  Ophthalmic  Ganglion. — This  arises  from  the  an- 
terior part  of  the  cavernous  plexus,  enters  the  orbit  between  the  third  nerve  and  the  oph- 
thalmic division  of  the  fifth,  and  unites  sometimes  with  the  long  root  of  the  ophthalmic 
ganglion,  which  we  have  stated  to  be  derived  from  the  nasal  branch  of  the  ophthalmic, 
and  sometimes  with  the  ophthalmic  ganglion  itself 

This  root  had  been  described  and  figured  by  Lecat,  before  Bock,  Ribes,  and  Arnold 
recalled  the  attention  of  anatomists  to  it. 

It  follows,  from  the  arrangement  just  described,  that  the  ophthalmic  ganglion  has  three 
roots,  two  cerebro-spinal  and  one  ganglionic. 

Communicating  Filaments  of  the  Fifth  Nerve. — Some  of  these  pass  to  the  Gasserian  gan- 
glion, and  others  to  the  ophthalmic  division  of  the  fifth.t 

The  Filaments  which  accompany  the  Internal  Carotid  Artery  and  its  Branches. — These 
are  extremely  delicate,  but  they  are  beautifully  distinct  in  some  subjects.  They  may 
be  followed  even  upon  the  branches  of  the  internal  carotid. 

Anatomists  admit  the  existence  of  a  plexus  for  the  ophthalmic  artery,  and  for  each  of 
its  subdivisions.     It  is  even  supposed  that  there  is  one  for  the  arteria  centralis  retinae. t 

Several  authors  have  described  a  certain  number  of  filaments  proceeding  from  the 
cavernous  plexus  to  the  pituitary  body  (filets  sus-sphenoidaux,  Chaussier).  I  have  nev- 
er been  fortunate  enough  to  discover  them,  nor  yet  the  ganglion  (the  ganghon  of  Ribes) 
which  is  said  to  exist  upon  the  anterior  communicating  artery  of  the  brain,  and  which 
is  found  at  the  point  of  junction  of  the  right  and  left  trunks  of  the  sympathetic. 

It  follows,  from  what  has  been  stated,  that  the  superior  cervical  ganglion,  by  means 
of  its  upper  or  carotid  branch,  communicates  with  most  of  the  nerves  of  the  anterior  cra- 
nial pair ;  namely,  with  the  fifth  nerve,  by  means  of  the  Gasserian  ganglion,  of  the  oph- 
thalmic division  of  the  fifth,  and  of  the  ophthalmic  ganglion,  either  directly  or  indirectly ; 
also  by  means  of  the  superior  maxillary  division  of  this  nerve,  through  the  intervention  of 
the  spheno-palatine  ganglion  ;  secondly,  with  the  third  nerve  ;  and,  lastly,  with  the  sixth. 

The  Anterior  Branches  from  the  Superior  Cervical  Ganglion. 

The  anterior  branches  of  the  superior  cervical  ganglion  establish  a  communication  with 
the  different  nerves  of  the  posterior  cranial  pair,  excepting  the  spinal  accessory  nerve, 
which  does  not  appear  to  have  any  direct  communication  with  it. 

The  glosso-pharyngeal  and  pneumogastric  nerves  communicate  with  the  superioi 
cervical  ganglion  at  two  different  points,  viz.,  at  their  ganglia,  and  by  their  branches. 

The  communication  of  the  superior  cervical  ganglion  with  the  ganglia  of  the  glosso-pha 
ryngeal  and  pneumogastric  nerves  has  been  pointed  out  by  Arnold  ;  it  is  difficult  to  dem 
onstrate  it  through  the  dense  tissue  which  surrounds  these  ganglia. 

On  the  contrary,  it  is  extremely  easy  to  demonstrate  the  communications  of  the  glos- 
so-pharyngeal nerve  and  the  plexiform  cord  of  the  pneumogastric  with  the  superior  cer- 
vical ganglion.  I  have  already  said  (see  Pneumogastric  Nerve)  that  in  one  case  I  found 
the  pneumogastric  so  closely  applied  to  the  whole  length  of  the  superior  cervical  gangli- 
on, that  it  was  impossible  to  separate  them.  The  communication  of  the  superior  cervi- 
cal ganglion  with  the  hypo-glossal  is  quite  as  evident  as  the  preceding. 

The  filaments  of  communication  with  the  nerves  forming  the  posterior  cranial  pair  do 
not  always  proceed  from  the  superior  cervical  ganglion  itself,  but  sometimes  from  its  ca. 
rotid  branch. 

*  I  have  never  seen  the  communication  between  the  superior  cervical  ganglion  and  the  facial  nerve  noticed 
by  some  anatomists. 

t  I  may  here  again  notice,  that  in  two  subjects  I  have  seen  a  twig  from  the  spheno-palatine  ganglion  join 
the  communicating  branches  between  the  sixth  nen-e  and  the  sympathetic. 

t  M.  Ribes,  Miimoires  de  la  Societfi  Medicale  d'EmuIatiun,  t.  vii. 

.5Q 


NEUROLOGY. 

The  External  Branch  from  the  Superior  Cervical  Ganglion 

The  external  branches  of  the  superior  cervical  ganglion  establish  a  communicatton  be- 
tween it  and  the  first,  second,  and  third  cervical  nerves ;  they  are  large,  have  a  gray  colour, 
and  a  ganglionic  structure  ;  we  may  regard  them  as  true  prolongations  of  the  superior 
cervical  ganglion ;  the  principal  of  them  enter  the  angle  of  bifurcation  of  the  second  cer 
vical  nerve,  into  its  ascending  and  descending  branches ;  the  others,  which  are  very 
small,  join  the  first  cervical  nerve.  They  constitute  a  true  ganglionic  plexus,  and  often 
form  two  distinct  groups. 

Frequently  the  superior  cervical  ganglion  communicates  only  with  the  first  and  sec- 
ond cervical  nerves.  At  other  times  it  also  communicates  with  the  third  and  fourth 
nerves  by  means  of  a  long  and  very  oblique  branch.  In  one  case  it  communicated  di- 
rectly with  the  phrenic  nerve. 

The  Inferior  Branch  from  the  Superior  Cervical  Ganglion. 

The  inferior  branch  from  the  superior  cervical  ganglion,  or  the  branch  of  communica 
tion  with  the  middle  cervical  ganglion,  is  a  white  cord,  resembling  a  spinal  nerve,  ex- 
cepting in  a  few  cases,  in  which  it  appears  to  be  a  prolongation  of  the  tissue  of  the  ganglion 
itself:  when  the  lower  extremity  of  the  superior  cervical  ganglion  is  divided  into  two 
parts,  its  inferior  branch  arises  from  the  external  division.  It  varies  much  in  size  in 
different  subjects  :  it  descends  vertically  in  front  of  the  spinal  column,  behind  the  com- 
mon carotid,  the  internal  jugular  vein,  and  the  pnemnogastric  nerve,  to  which  it  is  uni- 
ted by  a  very  loose  cellular  tissue. 

Having  reached  the  inferior  thyroid  artery,  the  cord  of  the  sympathetic  passes  behind 
that  vessel,  and  enters  the  middle  cervical  ganglion,  when  that  exists  ;  but  when  it  is  ab- 
sent, the  cord  continues  on  to  join  the  inferior  cervical  ganglion.  As  it  descends,  it  most 
commonly  receives  some  twigs  from  the  third  and  fourth  cervical  nerves,  which  twigs  we 
have  already  said  occasionally  enter  the  superior  cervical  ganglion.  At  its  origin,  it 
gives  off  on  the  inner  side  two  filaments,  which  join  the  superior  cardiac  nerve,  and  in- 
crease its  size ;  and  an  anastomotic  twig  to  the  external  laryngeal  nerve,  a  branch  of 
the  superior  laryngeal.  Not  unfrequently  the  superior  cardiac  nerve  arises  entirely  from 
the  communicating  branch  between  the  superior  and  middle  cervical  ganglia,  that  branch 
appearing  to  bifurcate. 

The  communication  between  the  superior  and  middle  cervical  ganglia  is  subject  to 
much  variety.  I  have  seen  a  small  ganglion  upon  it  opposite  to  the  inferior  thyroid  ar- 
tery ;  from  this  ganglion,  which  rested  upon  the  artery,  and  which  might  be  regarded  as 
the  vestige  of  a  middle  cervical  ganglion;  two  cords  proceeded,  an  anterior,  which  join- 
ed the  cardiac  nerve,  and  a  posterior,  which  ended  in  the  inferior  cervical  ganglion : 
both  of  these  had  a  gangliform  structure.  The  cord  of  the  sympathetic  is  not  uncom- 
monly found  enlarged  at  intervals  into  ganglionic  nodules. 

The  Internal  Branches,  or  Carotid  and  Visceral  Branches. 

The  internal  branches  from  the  superior  cervical  ganglion  are  divided  into  those  which 
accompany  the  external  carotid  and  its  ramifications,  and  those  which  are  distributed  to 
the  viscera. 

The  Carotid  Branches. — It  has  been  stated  that  from  the  upper  extremity  of  the  supe- 
rior cervical  ganglion  certain  branches  are  given  off,  which  surround  the  internal  carot- 
id, and  are  prolonged  upon  its  ramifications. 

From  the  inner  border  of  the  same  ganglion  other  branches  proceed,  which  embrace 
the  external  carotid  and  the  ramifications  of  that  vessel. 

These  nerves  are  of  a  gray  colour  (subruji),  of  a  soft  texture  (nervi  molles  et  pene  mu- 
cosi,  Scarpa),  and  of  a  knotted  and  gangliform  structure  (rami  gangliformes,  Neubauer) ; 
they  come  off  from  the  ganglion  opposite  to  the  origin  of  the  facial  artery ;  they  pass  in- 
ward behind  the  external  and  internal  carotids,  and  form  a  sort  of  gray  plexus,  which  ex- 
tends as  far  as  the  origin  of  the  internal  and  external  carotid  ;*  they  turn  like  a  loop 
around  the  former  of  these  vessels,  and  anastomose  with  the  carotid  filaments  from  the 
glosso-phaiyngeal,  and  from  the  pharyngeal  and  superior  laryngeal  branches  of  the  pneu- 
mogastric.  None  of  the  branches  from  this  plexus  are  prolonged  upon  the  conmuon  ca- 
rotid ;  they  all  pass  upon  the  external  carotid  and  its  different  ramifications,  forming  as 
many  plexuses  as  there  are  vessels,  and  are  distributed  with  those  vessels  to  the  neck 
and  the  face.  Thus,  there  is  a  thyroid  plexus,  which  surrounds  the  superior  thyroid  ar- 
tery, and  may  be  traced  into  the  thjToid  body ;  a  lingual  plexus,  which  enters  the  sub- 
stance of  the  tongue,  and  is  supposed  to  anastomose  with  the  lingual  branch  of  the  infe- 
rior maxillary  division  of  the  fifth,  and  even  with  the  hypo-glossal  nerve ;  and  &  facial 
plexus,  which  is  supposed  to  anastomose  with  the  facial  nerve.  Anatomists  have  par- 
ticularly directed  their  attention  to  the  branches  which  enter  the  sub-maxillary  gland  ; 
some  imagining,  and  others  regarding  it  as  certain,  that  these  branches  communicate 
with  the  sub-maxillaiy  ganglion.  I  have  never  been  fortunate  enough  to  discover  this 
communication. 

*  At  this  division  there  is  frequently  a  gangliform  enlargement,  which  Arnold  proposes  to  call  the  inter-ca- 
rotid ganglion. 


THE   MIDDLE   AND    INFERIOR    CERVICAL   GANGLIA.  8S9 

There  is,  moreover,  a  pharyngeal  plexus,  an  occipital  plexus,  and  an  auricular  plexus  : 
the  elder  Meckel*  has  even  described  an  anastomosis  between  the  facial  nerve  and  the 
sympathetic  filament  which  accompanies  the  posterior  auricular  artery.  Lastly,  the 
temporal  artery,  and  the  internal  maxillary  artery  and  its  divisions,  are  also  surrounded 
(hederae  ad  modum,  Scarpa)  by  small  nervous  plexuses  ;  these  plexuses  are  sometimes 
so  well  developed,  that  the  elder  Meckel  states  that  the  arteries  of  the  face  have  larger 
nervous  plexuses  than  any  others  in  the  body.  These  plexuses  appear  to  me  to  be  pe- 
culiarly remarkable  for  containing  a  mixture  of  white  fibres  and  nervi  molles,  which 
proves  their  double  origin. 

All  these  plexuses  present  gangliform  enlargements  at  various  points,  as  is  shown  in 
the  splendid  plate  in  Scarpa's  work.t  This  author  has  figured,  after  Andersh,  a  gangli- 
on which  he  believes  to  be  constant  at  the  division  of  the  external  carotid  and  temporal 
arteries.     A  twig  from  the  facial  nerve  terminates  in  this  ganghon.f 

The  Visceral  Branches. — All  these  come  off  from  the  inner  side  of  the  ganglion,  and 
divide  into  pharyngeal,  laryngeal,  and  cardiac  branches. 

The  pharyngeal  branches  are  certain  thick  ganglionic  cords  which  arise  from  the  upper 
and  inner  part  of  the  superior  cervical  ganglion,  pass  transversely  inward,  and  combine 
with  the  pharyngeal  branches  of  the  glosso-pharyngeal  and  pneumogastric  nerves  to 
form  one  of  the  most  remarkable  plexuses  in  the  body,  which  is  distributed  to  the  pha- 
rynx. To  this  plexus  must  be  relterred  all  those  highly  important  nervous  phenomena 
which  are  manifested  in  connexion  with  the  pharynx,  more  particularly  the  sensation  of 
thirst. 

•  The  laryngeal  branches  unite  with  the  superior  laryngeal  nerve  and  its  divisions.  In  a 
case  in  which  the  external  laryngeal  nerve  arose  separately  from  the  pneumogastric  and 
not  from  the  superior  laryngeal,  it  had  as  many  filaments  of  origin  from  the  superior 
cervical  ganglion  as  from  the  pneumogastric  itself 

The  cardiac  branches  form  the  superior  cardiac  nerve,  to  which  I  shall  recur  after  hav 
ing  described  the  middle  and  inferior  cervical  ganglia. 

The  Middle  Cervical  Ganglion. 

The  middle  cervical  ganglion  {a,  Jig.  302)  is  wanting  in  a  great  number  of  subjects,  and 
then  the  branches  usually  given  off  from  and  received  by  it  are  given  off  and  received 
by  the  cords  which  connect  the  superior  and  inferior  cervical  ganglia,  or  by  the  inferior 
cervical  ganglion  itself  The  middle  cervical  ganglion  is  sometimes  double ;  at  othe'' 
times  it  is  in  quite  a  rudimentary  state. 

It  is  situated  on  a  level  with  the  fifth  or  sixth  cervical  vertebra,  in  front  of  the  inferior 
thyroid  artery,  opposite  to  the  first  curve  of  that  vessel,  and  sometimes  behind  it ;  its 
relation  to  this  artery,  which  is  very  nearly  constant,  induced  Haller  to  name  it  the  thy- 
roid ganglion :  however,  I  have  frequently  seen  it  eight  lines  above  that  artery.  Its 
form  and  size  are  extremely  variable,  not  only  in  different  subjects,  but  even  upon  oppo- 
site sides  of  the  same  subject.'  Sometimes  it  is  a  simple  gangliform  enlargement. 
Scarpa  has  figured  a  middle  cervical  ganglion  almost  as  large  as  the  superior,  and,  like 
it,  olive-shaped.     I  have  never  seen  it  as  large  as  this.^ 

The  middle  cervical  ganglion,  when  it  exists,  receives, 

Above,  the  cord  which  communicates  with  the  superior  cervical  ganglion ;  below,  the 
cord  of  communication,  often  multiple,  with  the  inferior  cervical  ganglion  ;  on  the  out 
side,  three  branches,  derived  from  the  third,  fourth,  and  fifth  cervical  nerves :  not  un- 
frequently  the  communicating  branch  from  the  fourth  cervical  nerve  belongs  to  the 
phrenic  ;  on  the  inside,  the  middle  cardiac  nerve,  or  great  cardiac  of  Scarpa,  which  I  shall 
presently  describe. 

The  size  of  the  middle  cervical  ganglion  has  always  appeared  to  me  to  be  proportioned 
to  that  of  its  filaments  of  communication  with  the  cervical  nerves. 

The  Inferior  Cervical  Ganglion. 
Neubauer  has  given  an  excellent  description  of  the  inferior  cervical  ganglion,  under 
the  name  of  the  first  thoracic  ganglion,  rather  an  appropriate  title  for  it,  because  it  is  fre- 
quently continuous  with  the  first  thoracic  ganglion  (as  at  i,  fig.  302) ;  and,  secondly,  be- 
cause it  is  situated  in  front  of  the  transverse  process  of  the  seventh  cervical  vertebra 
and  of  the  head  of  the  first  rib.  This  ganglion  is  constant ;  it  is  deeply  seated  behind 
the  origin  of  the  vertebral  artery,  by  which  it  is  completely  concealed.  Ii 

*  M6moires  de  I'Acad.  de  Berlin,  1752.  t  Tabulae  Neurologicae,  tab.  iii.,  1794. 

T  Arnold  has  described  and  figured  a  twig  from  the  plexus  which  surrounds  the  middle  meningeal  or  spheno- 
spinous  artery,  and  which,  according  to  this  laborious  inquirer,  terminates  in  the  otic  ganglion  ;  he  also  de 
scribes  some  nervous  twigs  passing  from  the  plexus  of  the  ascending  palatine  artery  to  the  sub-maxillary 
ganglion.  In  this  way  he  establishes  a  connexion  between  the  sympathetic  system  and  these  two  cranial  gan- 
glia. I  have  devoted  great  care  to  this  subject,  but  have  never  been  able  to  make  out  these  communicating 
filaments,  even  though  all  the  difficult  dissections  have  been  made  upon  specimens  previously  macerated  in 
diluted  nitric  acid. 

1)  I  believe  that  it  is  incorrect  to  regard  as  a  middle  cervical  ganglion  those  ganglionic  nodules,  without 
either  afferent  or  efferent  filaments,  which  are  rather  frequently  found  at  various  points  on  the  trunk  of  the 
sympathetic. 

H  It  is  not  rare  to  see  the  inferior  cervical  ganglion  describe  around  the  vertebral  artery  a  half  ring,  which 
is  completed  in  front  by  a  gray  cord  extended  from  one  end  of  the  ganglion  to  the  other. 


860  NEUROLOGY. 

It  is  of  a  semilunar  shape,  its  concave  border  being  turned  upward  and  its  convex  one 
downward ;  at  its  internal  extremity  it  receives  the  trunk  of  the  sympathetic  ;  at  its  ex- 
ternal extremity  it  receives  a  large  nerve  which  accompanies  the  vertebral  artery,  and 
which  may  be  called  the  vertebral  nerve ;  at  the  same  extremity  it  also  receives  some 
communicating  branches  from  the  fifth,  sixth,  and  seventh  cervical  nerves,  and  often 
from  the  first  dorsal.  Several  branches  proceed  from  its  convex  border,  which  is  turned 
downward  ;  some  pass  in  front  of  and  others  behind  the  sub-clavian  artery,  which  they 
embrace  like  loops.  Most  of  these  inferior  branches  are  the  communicating  branches 
between  the  inferior  cervical  and  the  superior  thoracic  ganglion,  and  they  exist  even 
when  the  two  ganglia  are  directly  continuous  with  each  other.  One  of  the  branches 
sometimes  joins  the  recurrent  laryngeal  branch  of  the  pneumogastric  ;  the  most  remark- 
able of  the  inferior  branches  constitutes  the  inferior  cardiac  nerve,  which  is  rather  fre- 
quently derived  from  the  superior  thoracic  ganglion. 

To  complete  the  description  of  the  cervical  portion  of  the  sympathetic,  we  have  now 
only  to  speak  of  the  vertebral  nerve  and  of  the  cardiac  nerves. 

The  Vertebral  Plexus. 
The  vertebral  plexus  or  vertebral  nerve  occupies  the  canal  which  is  formed  for  the  verte- 
bral artery  in  the  transverse  processes.  It  is  generally  said  that  this  nerve  arises  from 
the  inferior  cervical  ganglion  ;  that  it  traverses  the  entire  length  of  the  canal  formed  for 
the  vertebral  artery,  enters  the  cranium  with  that  vessel,  and  then  unites  with  its  fel- 
low of  the  opposite  side  to  form  the  basilar  plexus,  which  divides  and  subdivides  around 
the  terminal  ramifications  of  the  basilar  artery,  like  the  plexuses  which  are  formed 
around  the  internal  carotid  ;  but  such  is  not  a  correct  description  of  the  nerve.  It  ap- 
pears to  me  to  be  formed  by  the  junction  of  filaments  derived  from  the  third,  fourth,  and 
fifth  cervical  nerves,  gradually  to  increase  in  size  from  above  downward  as  it  receives 
new  filaments,  then  to  pass  behind  the  artery,  to  emerge  from  the  canal  also  behind  the 
vessel,  and,  finally,  to  enter  the  inferior  cervical  ganglion.  I  conceive  that  this  branch 
is  intended  to  establish  a  communication  between  the  third,  fourth,  and  fifth  cervical 
nerves  and  the  inferior  cervical  ganglion.  I  have  never  found  upon  these  branches  the 
swellings  or  gangli  which,  according  to  M.  Blainville's  ingenious  idea,  might  be  intend- 
ed to  supply  the  place  of  the  cervical  sympathetic  ganglia,  and  to  destroy  the  appear- 
ance of  irregularity  which  exists  in  the  cervical  region  in  this  respect. 

The  Cardiac  Jferves. 

Dissection. — This  comprises  the  dissection  of  the  cardiac  nerves,  from  their  origin  to 
the  point  where  the  aorta  and  pulmonary  artery  cross  each  other  ;  and  from  that  point 
to  the  extreme  divisions  of  the  nerves.  For  this  purpose,  after  having  previously  ex- 
posed the  cervical  ganglia  and  the  cardiac  nerves,  the  preparation  should  be  macerated 
in  diluted  nitric  acid  ;  all  the  internal  nerves  which  proceed  from  the  ganglion  should 
then  be  carefully  dissected,  so  as  to  preserve  their  relations  with  the  cardiac  branches 
of  the  pneumogastric  and  recurrent  nerves ;  we  must  then  examine  the  nerves  which 
pass  in  front  of  the  aorta,  those  which  run  between  that  vessel  and  the  pulmonary  ar- 
tery and  trachea,  and,  lastly,  those  which  pass  behind  the  pulmonary  artery  ;  we  should 
study,  at  the  same  time,  their  relations  with  the  anterior  and  posterior  cardiac  plexuses. 

The  cardiac  nerves,  or  nerves  of  the  heart,  which  are  distinguished  into  the  right  and 
the  left,*  arise  essentially  from  the  cervical  ganglia.  These  ganglionic  nerves  are  then 
joined  by  several  branches  from  the  pneumogastric ;  they  all  converge  upon  the  origin 
of  the  aorta  and  pulmonary  artery  to  form  the  cardiac  plexuses,  which  give  off  the  right 
and  left  coronari/  plexuses  ;  these  latter  plexuses  surround  the  coronary  arteries,  and  their 
branches  are  scattered  over  the  surface  of  the  heart,  but  do  not  enter  its  substance  un- 
til they  have  advanced  a  considerable  distance  beneath  the  serous  membrane  by  which 
the  heart  is  covered. 

Such  is  the  most  general  idea  that  can  be  given  of  the  cardiac  nerves  and  plexuses, 
which  afford  one  example  of  the  most  remarkable  of  the  median  anastomoses.  Scarpa 
first  described  and  figured  them  correctly  in  his  plates,  which  will  always  be  models  for 
anatomical  drawings.  No  nerves  present  so  many  varieties,  in  number,  size,  and  ori- 
gin, as  the  cardiac  nerves  ;  and  on  this  subject  especially,  the  want  of  a  work  upon  ana- 
tomical varieties  is  especicilly  felt.  For  my  part,  I  declare  that  I  have  never  found  the 
cardiac  nerves  in  my  dissections  as  they  are  represented  in  Scarpa's  magnificent  plates, 

*  The  history  of  flie  nerves  of  the  heart  is  singular.  The  ancient  philosophers,  with  Aristotle,  influenced 
by  certain  preconceiited  ideas,  staled  that  the  heart  was  the  source  of  all  the  nerves  in  the  body.  Galen  re- 
futed this  opinion,  and  J^dmitted  that  the  heart  had  but  one  very  small  nerve,  which  descended  from  the  brain. 
Vesalius  considered  that  this  slender  nerve  came  from  the  recurrent,  and  represented  it  in  a  figure.  Fallo 
pius  first  described  the  nerves  of  the  heart,  and  says  that  he  showed  his  audience  "  insignem  nervorum  plexum 
»  quo  ahundans  copia  nervosa  materia  totam  cordis  basim  complexatur,  pergue  ipsam  plures  propagines  parvo- 
rum  nervorum  dispergit."  Behrends,  in  1792,  defended  a  thesis  in  which  he  endeavoured  to  demonstrate  that 
the  heart  has  no  nerves,  cornervis  carere.  Such  was  the  amount  of  knowledge  on  this  subject  when,  in  1794, 
Scarpa  published  his  splendid  work,  and  settled  the  state  of  science  on  this  point. — (.Tabulae  Neurohgicee  ad 
Illustrandam  Anatomiam  Cardiacorum  Nervorum,  Noni  Nervorum  Cerebri,  Glosso-pharyngax  et  Pharynga:i  ex 
Octavo  Cerebri.) 


THE    RIGHT    CARDIAC    NERVES.  Wfl 

which  have  served  as  the  type  for  all  descriptions.  I  have  minutely  described  the  cardiac 
nerves  in  eight  different  subjects  ;  these  eight  descriptions  present  very  great  differen- 
ces, at  least,  until  one  arrives  at  the  account  of  the  cardiac  plexuses  ;  the  ultimate  dis- 
tribution of  the  nerves  of  the  heart  appeared  to  be  the  same  in  all  these  subjects. 

All  the  cardiac  nerves  are  gray,  but  they  are  not  all  soft,  as  declared  by  Scarpa,  who 
called  them  nervi  molles.  Sometimes  the  right,  and  sometimes  the  left  cardiac  nerves, 
are  the  larger  ;  the  nerves  of  the  two  sides  are  inversely  proportioned  to  each  other  in 
this  respect,  and  there  is  evidently  a  mutual  dependance  between  them.  In  one  case,  in 
which  tlie  middle  and  inferior  cardiac  nerves  of  the  right  side  were  wanting,  and  the 
superior  cardiac  nerve  very  small,  their  places  were  supplied  by  some  large  branches 
from  the  right  recurrent  nerve,  and  by  the  left  cardiac  nerves,  which  were  largely  de- 
veloped. 

Anatomists  follow  Scarpa  in  describing  three  cardiac  nerves  on  each  side  :  a  superior, 
named  by  him  the  superficial  cardiac  nerve,  which  is  derived  from  the  superior  cervical 
ganglion  ;  a  middle,  called  by  him  the  great  or  deep  cardiac  nerve,  which  arises  from  the 
middle  cervical  ganglion  ;  and  an  inferior,  or  small  cardiac  nerve,  proceeding  from  the 
inferior  cervical  ganglion.  Although  this  is  the  usual  arrangement,  it  is  often  impossible 
to  distinguish  three  nerves,  in  consequence  of  the  anatomical  varieties  which  I  have  al- 
ready mentioned.  There  is  frequently  no  middle  cardiac  nerve  properly  so  called  ;  at 
other  times  there  is  no  inferior  cardiac  nerve,  or,  rather,  they  are  both  in  a  rudimentary 
state  ;  lastly,  the  superior  cardiac  nerve,  if  not  entirely  wanting,  may  be  extremely  small, 
and  may  join  the  middle  cardiac  nerve.  Sometimes  all  the  cardiac  nerves  of  one  side 
unite  into  a  single  trunk,  or  else  into  a  plexus  situated  behind  the  sub-clavian  artery, 
upon  the  side  of  the  trachea  ;  the  recurrent  nerve  assists  in  forming  this  plexus,  from 
which  three,  four,  or  more  branches  are  given  off  to  be  distributed  to  the  heart  in  the 
usual  manner.  One  of  the  most  important  points  in  the  history  of  the  cardiac  nerves  is 
their  sort  of  fusion  with  the  pneumogastric,  which  is  so  intimate  that  the  cardiac  branch- 
es of  the  pneumogastric,  and  those  which  come  from  the  ganglia,  form  a  single  system. 
There  is  a  similar  fusion  between  the  superior,  middle,  and  inferior  cardiac  nerVes  of 
each  side,  and  between  the  nerves  of  the  two  sides. 

The  recurrent  nerve,  in  particular,  appears  sometimae  to  be  distributed  equally  to  the 
larynx  and  the  heart,  so  large  and  numerous  are  the  cardiac  branches  given  off  from  it ; 
it  will  hereafter  be  seen  that  there  is  an  equally  intimate  connexion  between  the  pneu- 
mogastric nerve  and  the  solar  plexus. 

I  shall  first  describe  in  detail  the  right  cardiac  nerves,  and  shall  then  briefly  point  out 
the  differences  between  them  and  the  left  cardiac  nerves. 

The  Right  Cardiac  Nerves. 

The  Superior  Cardiac  Nerve. — Its  origin  is  very  variable.  Most  commonly,  it  arises 
from  the  internal  division  of  the  bifurcated  lower  extremity  of  the  superior  cervical  gan- 
glion, the  cord  of  communication  between  the  superior  and  the  next  cervical  ganglion 
forming  the  external  division.  At  other  times  it  arises  from  the  communicating  cord. 
In  a  great  number  of  cases  it  has  several  origins,  being  formed  by  two  or  three  very 
small  filaments,  which  come  from  the  inner  side  of  the  superior  cervical  ganglion  ;  by  a 
branch,  often  a  large  one,  from  the  cord  of  communication  ;  and  by  two  filaments  from 
the  pneumogastric  nerve.  In  one  of  these  latter  cases  the  cardiac  branch  from  the  cord 
of  conmiunication  presented  a  very  distinct  ganglion. 

Whatever  may  be  its  origin,  the  superior  cardiac  nerve  passes  obliquely  doTvnward  and 
inward,  behind  the  common  carotid,  from  which  it  is  separated  by  a  very  thin  layer  of 
fascia,  so  that  it  is  almost  impossible  to  include  it  in  applying  a  ligature  to  that  artery ; 
it  runs  along  the  trachea,  very  often  receives  a  branch  from  the  trunk  of  the  sympathet- 
ic, and  crosses  in  front  of  the  inferior  thyroid  artery,  or  sometimes  divides  into  two  branch- 
es, one  of  which,  the  anterior,  passes  in  front  of  the  artery,  while  the  posterior  joins  the 
recurrent  nerve.*  At  the  lower  part  of  the  neck  the  superior  cardiac  nerve  runs  along 
the  recurrent  laryngeal  nerve,  with  which  it  may  be  confounded  ;  it  enters  the  thorax, 
passing  behind  and  sometimes  in  front  of  the  sub-clavian  artery,t  runs  along  the  brachio- 
cephalic trunk,  gains  the  back  of  the  arch  of  the  aorta,  gives  off  a  certain  number  of  fila- 
ments, which  pass  in  front  of  that  part  of  the  vessel,  then  runs  obliquely  downward  and 
to  the  lelt  between  the  arch  of  the  aorta  and  the  trachea,  anastomoses  very  fi-equently 
with  the  middle  and  inferior  cardiac  nerves  and  with  the  branches  of  the  recurrent,  and 
divides  into  two  sets  of  filaments  ;  some  of  these  pass  between  the  aorta  and  the  pul- 
monary artery,  and  others  between  the  right  puhnonary  trunk  and  the  trachea ;  they  both 

*  The  trunk  of  the  sympathetic,  havin?  reached  the  inferior  thyroid  artery,  sometimes  divides  into  two 
branches,  one  of  which  passes  in  front  of  that  artery,  to  join  the  superior  cardiac  nerve,  while  the  other  passes 
behind  it  to  the  inferior  cervical  ganglion  ;  not  nnfrequently  the  superior  OM-diac  nerve  presents  a  ganglionic 
enlargement,  which  occupies  the  whole  or  a  part  of  the  thickness  of  the  nerve. 

t  The  superior  cardiac  nerve  often  bifurcates  so  as  to  embrace  the  sub-clavian  artery  in  a  complete  ring. 
At  other  times  the  superior  cardiac  nerve  passes  liehind  the  sub-clavian  artery,  and  the  cardiac  branch  of  the 
pneumogastric  in  front  of  it,  so  as  to  form  beneath  the  sub-clavian  an  anastomotic  loop,  which  lies  to  the  inner 
side  of  the  one  formed  by  the  recurrent  nerve.  Most  commonly  the  cardiac  branch  of  the  pneumogastric  anas 
tomoses  with  the  superior  cardiac  nerve,  between  the  arch  of  the  aorta  and  the  trachea. 


862  NEUROLOGY. 

anastomose  with  the  left  cardiac  nerves,  and  are  arranged  as  we  shall  soon  describe.  In 
some  rare  cases,  the  right  superior  cardiac  nerve  goes  directly  to  the  cardiac  plexus, 
without  anastomosing  with  the  middle  and  inferior  cardiac  nerves. 

During  its  course  along  the  neck,  the  right  superior  cardiac  nerve  receives  the  small 
superior  cardiac  branches  of  the  pneumogastric,  and  gives  off  several  filaments,  some  to 
the  pharynx,  others  to  the  trachea  and  the  thyroid  body,  while  several  assist  in  forming 
the  plexus  of  the  inferior  thyroid  artery ;  it  often  gives  off  three  or  four  branches  which 
anastomose  with  the  recurrent  nerve. 

In  the  thorax,  the  superior  cardiac  nerve  is  joined  by  the  cardiac  branch  given  off  by 
the  pneumogastric  in  the  lower  part  of  the  neck,  and  which  is  sometimes  of  very  consid- 
erable size,  and  evidently  re-enforces  the  cardiac  nerve ;  this  branch  of  the  pneumogas- 
tric sometimes  terminates  directly  in  the  cardiac  plexus. 

The  Middle  Cardiac  Nerve. — This  nerve  arises  from  the  middle  cervical  ganglion,  or, 
when  that  is  absent,  from  the  trunk  of  the  sympathetic,  at  a  variable  distance  from  the 
inferior  cervical  ganglion.  It  is  rather  frequently  the  largest  of  the  cardiac  nerves,  and 
has,  therefore,  been  called  by  Scarpa  the  great  cardiac  nerve  {magnus,  jirofundus).  At 
other  times  it  is  in  a  rudimentary  state,  and  is  replaced  either  by  the  superior  or  the  in- 
ferior cardiac  nerve,  or  by  branches  from  the  recurrent :  it  frequently  divides  into  sev- 
eral twigs,  between  which  the  sub-clavian  passes  ;  it  almost  always  anastomoses  with  the 
superior  and  inferior  cardiac  nerves  of  the  same  side,  runs  along  the  recurrent  nerve,  for 
which  it  might  be  mistaken,  and  with  which  it  is  always  connected,  and  then  terminates 
in  the  cardiac  plexus. 

The  Inferior  Cardiac  Nerve. — This  is  generally  smaller  {cardiacus  minor)  than  the  pre- 
ceding nerve,  though  it  is  sometimes  larger ;  it  usually  arises  from  the  inferior  cervical 
ganglion,  but  rather  fequently  from  the  first  thoracic  ;  it  accompanies  the  middle  cardi- 
ac nerve,  anastomoses  with  that  nerve,  and,  like  it,  descends  vertically  in  front  of  the 
trachea,  and  terminates  in  the  cardiac  plexus. 

The  connexion  of  the  middle  and  inferior  cardiac  nerves  with  the  recurrent  nerve  de- 
mands especial  attention.  Sometimes  the  recurrent  sends  off  certain  large  branches 
which  join  the  cardiac  nerves,  and  form  their  principal  origin.  I  have  seen  the  middle 
and  inferior  cardiac  nerves  united  together,  crossing  over  the  recurrent  nerve  at  right 
angles,  and  adhering  intimately  to  it  without  presenting  that  admixture  of  filaments  which 
constitutes  an  anastomosis.* 

The  Left  Cardiac  Nerves. 

The  peculiarities  of  the  left  cardiac  nerves  maybe  stated  in  a  few  words  :t  in  the  neck, 
they  are  situated  in  front  of  the  oesophagus,  on  account  of  the  position  of  that  canal. 
The  connexions  between  the  cardiac  nerves  and  the  recurrent  on  the  left  side  appear  to 
me  more  numerous  than  those  on  the  right.  In  one  case,  the  superior  and  inferior  car- 
diac nerves  gave  off  a  series  of  four  rather  large  filaments,  which  ran  along  the  recur- 
rent, left  that  nerve  opposite  to  its  point  of  reflection,  and  then  terminated  in  the  usual 
manner.  I  ascertained  that,  in  this  case,  the  two  nerves  were  merely  in  contact,  and 
did  not  anastomose. 

In  the  thorax,  the  superior  and  middle  cardiac  nerves  of  the  left  side  descend  between 
the  carotid  and  sub-clavian,  and  then  run  upon  the  concavity  of  the  arch  of  the  aorta  ; 
the  inferior  cardiac  nerve,  which  is  the  largest  of  all  the  cardiac  nerves  in  a  subject 
which  I  have  now  before  me,  passes  to  the  left  of  the  trunk  of  the  pulmonary  artery, 
turns  round  its  back  part,  and  embraces  it  in  a  loop,  so  as  to  enter  that  portion  of  the 
cardiac  plexus  which  is  situated  between  the  aorta  and  the  right  division  of  the  pulmo- 
nary artery.  Lastly,  on  the  left  side,  more  commonly  than  on  the  right,  the  anterior 
pulmonary  plexus  sends  off  some  filaments  to  this  same  part  of  the  cardiac  plexus. 

The  Cardiac  Ganglion  and  Plexuses. 

We  have  seen  that  the  cardiac  nerves  of  the  same  side  anastomose  with  eacn  other 
on  the  sides  or  in  front  of  the  trachea.  Besides  this,  the  right  cardiac  nerves  anasto- 
mose with  the  left  upon  the  concavity  of  the  arch  of  the  aorta  ;  also  in  front  of  the  tra- 
chea, above  the  right  pulmonary  artery  ;  and,  lastly,  in  the  anterior  and  posterior  coro- 
nary plexuses. 

Wrisberg  was  the  first  to  describe  a  ganglion  in  the  situation  of  the  first-named  anas- 
tomosis, that  is  to  say,  upon  the  concavity  of  the  arch  of  the  aorta,  between  that  vessel 
and  the  pulmonary  artery,  to  the  right  of  the  remains  of  the  ductus  arteriosus.  This 
ganglion,  which  is  by  no  means  constant,  is  named  the  cardiac  ganglion  ;  it  is  joined  [so 
as  to  form  the  superficial  cardiac  plexus]  by  the  superior  cardiac  nerve  of  the  right  side, 

*  It  is  especially  in  these  anastomoses  between  the  cardiac  and  recurrent  nerves  that  I  have  been  able, 
from  the  different  aspect  of  the  iiljuaents  of  each,  to  ascertain  that  the  anastomoses  of  nerves  are  often  mere- 
ly apparent,  and  consist  of  a  simple^uxtaposition  of  two  nerves  without  any  communication  of  their  component 
fasciculi,  which  can  be  traced  uninterruptedly  from  their  entrance  to  their  emergence.  The  same  observa- 
tion applies  also  to  some  of  the  anastomoses  between  nerves  of  the  same  kind. 

t  In  one  subject,  three  filaments  arose  from  the  left  superior  cervical  ganglion,  and  united  in  a  small  gan- 
glionic nodule,  which  also  received  a  twig  from  the  laryngeal  nerve.  This  ganglionic  nodule  gave  off  several 
pharyngeal  twigs,  and  also  the  superior  cardiac  nerve 


THORACIC  PORTION  OP  THE  SYMPATHETIC  SYSTEM.       863 

by  the  same  nerve  of  the  left  side,  and  sometimes  also  by  the  right  and  left  cardiac 
branches  given  off  from  the  pneumogastric  nerves  in  the  lower  part  of  the  neck. 

The  second  anastomosis,  or  that  which  takes  place  in  front  of  the  trachea,  above  the 
right  pulmonary  artery,  and  behind  the  arch  of  the  aorta,  has  been  known,  since  the  time 
of  Haller,  as  thJB  great  cardiac  plexus  (magnus,  profundus  plexus  cardiacus,  Scarpa).  A 
ganglionic  enlargement  is  not  unfrequently  found  at  the  junction  of  the  principal  branch- 
es. This  great  cardiac  plexus  is  chiefly  formed  by  the  middle  and  inferior  cardiac  nerves 
of  both  sides  :  [it  also  receives  part  of  the  right  superficial  nerves.]  Lastly,  all  the  car- 
diac nerves  end  in  the  third  set  of  anastomoses,  namely,  those  upon  the  anterior  and 
posterior  coronary  arteries  around  the  root  of  the  aorta. 

Great  as  the  variety  may  be  in  the  course  and  size  of  the  cardiac  nerves  up  to  the 
origin  of  the  great  vessels  from  the  heart,  there  is  as  constant  a  uniformity  in  their  ar- 
rangement around  those  vessels,  and  in  their  ultimate  distribution  to  the  heart. 

Upon  the  origin  of  the  great  vessels,  the  cardiac  nerves  are  arranged  in  three  layers 
or  sets. 

The  superficial  layer  of  nerves  is  the  smallest ;  it  occupies  the  anterior  surface  of  the 
arch  of  the  aorta,  and  especially  its  right  side  ;  the  nerves  are  visible  without  any  dis- 
section through  the  transparent  pericardium  ;  they  all  pass  {v)  to  the  anterior  coronary 
artery,  to  the  right  side  of  the  infundibulum  of  the  right  ventricle.  In  this  superficial 
layer,  the  superficial  cardiac  plexus,  may  be  included  the  ganglion  of  Wrisberg,  when  it 
exists,  and  its  several  branches,  which  in  a  great  measure  assist  in  forming  the  anterior 
coronary  plexus. 

The  middle  layer  of  nerves  is  composed  of  two  very  distinct  parts,  viz.,  of  the  great  or 
deep  cardiac  plexus  of  Haller,  which  is  situated  between  the  trachea  and  the  arch  of  the 
aorta,  above  the  right  pulmonary  artery  ;  and  of  a  much  smaller  part,  situated  below  the 
great  cardiac  plexus,  from  which  it  is  derived,  and  between  the  right  pulmonary  artery 
and  the  arch  of  the  aorta.  In  order  to  obtain  a  good  view  of  this  layer,  the  arch  of  the 
aorta  must  be  cut  through. 

The  deep  layer  of  nerves  is  situated  between  the  right  pulmonary  artery  and  the  bifur- 
cation of  the  trachea.  The  trunk  of  the  pulmonary  artery  must  be  divided  in  order  to 
expose  it. 

The  Anterior  and  Posterior  Coronary  Plexuses. — ^The  whole  of  the  superficial  cardiac 
plexus  or  superficial  layer  of  nerves  ends  in  the  anterior  coronary  plexus  (»)  which  sur- 
rounds the  right  coronary  artery.  The  middle  and  posterior  layers  unite  below  the  right 
pulmonary  artery,  in  front  of  the  auricles,  to  form  a  plexus,  which  might  more  properly 
be  named  the  great  or  deep  cardiac  plexus  than  the  interlacement  so  called  by  Haller. 
From  this  plexus,  into  which  the  left  inferior  cardiac  nerve  enters  directly,  the  follow- 
ing branches  proceed :  anterior  auricular  branches,  which  are  very  numerous ;  certain 
branches  which  pass  between  the  aorta  and  the  pulmonary  artery  to  gain  the  right  side 
of  the  infundibulum,  and  join  the  anterior  coronary  plexus,  which,  as  we  have  seen  al- 
ready, is  derived  from  the  superficial  cardiac  plexus  ;  lastly,  the  branches  for  the  poste- 
rior coronary  plexus,  which  surrounds  the  origin  of  the  left  coronary  artery,  and  divides, 
like  that  vessel,  into  two  secondary  plexuses,  one  of  which  runs  round  the  left  auriculo- 
ventricular  furrow,  while  the  other  (»')  enters  the  anterior  ventricular  furrow. 

The  nervous  filaments  from  these  plexuses  soon  leave  the  ramifications  of  the  arter- 
ies ;  they  proceed  separately ;  they  are  all  equally  small,  and  can  be  seen  without  any 
dissection,  like  white  lines,  extending  from  the  base  towards  the  apex  of  the  heart. 
They  all  belong  to  the  ventricular  portion  of  the  heart ;  a  few  of  them,  however,  ascend 
on  the  posterior  surface  of  the  auricles,  which  are  much  more  abundantly  supplied  upon 
their  anterior  surface. 

The  cardiac  nerves  are  not  entirely  distributed  to  the  heart ;  several  of  them  are  lost 
in  the  coats  of  the  aorta,  some  join  the  anterior  pulmonary  plexus,  and  some  ramify  in 
the  pericardium. 

The  Thoracic  Portion  of  the  Sympathetic  System. 
In  the  thorax,  the  trunk  of  the  sympathetic  (i  t,  fig.  302)  consists,  on  each  side,  of  a 
grayish  cord,  having  as  many  nodules  or  ganglia  upon  it  as  there  are  vertebrae.  This 
cord  is  situated,  not  in  front  of  the  dorsal  vertebrae,  but  in  front  of  the  heads  of  the  ribs, 
to  which  the  gangUa  for  the  most  part  correspond :  the  two  superior  thoracic  ganglia 
are  the  largest,  and  are  almost  always  united ;  the  succeeding  ganglia  are  almost  of 
equal  size,  the  twelfth  being  next  in  size  to  the  first  and  second.  The  ganglionic  struc- 
ture is  observed  throughout  the  whole  extent  of  this  part  of  the  sympathetic,  so  that 
the  cords  of  communication  between  the  ganglia  may  be  said  to  be  merely  prolongations 
of  the  ganglia.  In  some  subjects  the  ganglia  cannot  be  distinguished  from  the  portions 
of  the  sympathetic  trunk  above  and  below  them,  except  by  the  branches  which  enter 
and  converge  from  those  points  ;  it  would,  therefore,  be  a  serious  anatomical  error  to 
regard  the  portions  of  the  trunk  between  the  ganglia  as  mere  filaments  of  communica- 
tion. In  some  subjects  the  cords  between  the  ganglia  are  divided  into  two  or  three  fila- 
ments.    The  varieties  observed  in  the  number  of  the  thoracic  ganglia  are  rather  appa- 


864  NEUROLOGY. 

rent  than  real :  tliey  depend,  some  upon  fusion  of  the  first  thoracic  ganglion  with  the 
inferior  cervical  ganglion,  or  of  the  first  and  second  thoracic  ganglia ;  others  upon  fusion 
of  two  central  ganglia,  or  upon  that,  which  is  more  common,  of  the  last  thoracic  with 
the  first  lumbar  ganglion  ;  upon  a  transposition  of  the  last  thoracic  ganglion,  which  is 
then  found  upon  the  first  lumbar  vertebra  ;  and,  lastly,  upon  the  two  inferior  thoracic 
ganglia  being  situated  in  the  last  intercostal  space.  Besides  this,  the  three  lowest  tho- 
-acic  ganglia  are  subject  to  much  variety,  both  in  situation  and  in  shape  ;  and  the  same 
may  be  said  of  the  mode  of  connexion  between  the  twelfth  thoracic  and  the  first  lumbar 
ganglion. 

The  thoracic  portion  of  the  sympathetic  lies  beneath  the  pleura  and  the  very  thin 
fibrous  layer  by  which  that  membrane  is  strengthened.  It  can  be  distinctly  seen  with- 
out any  dissection,  in  consequence  of  the  transparency  of  these  layers.  The  intercos- 
tal arteries  and  veins  pass  behind  it ;  on  the  right  side,  the  vena  azygos  runs  along  it. 

The  thoracic  portion  of  the  sympathetic  gives  off  external  branches,  or  branches  of 
communication  with  the  dorsal  nerves  ;  and  the  internal  branches,  which  are  intended 
for  the  aorta  and  the  abdominal  viscera. 

The  External  or  Spinal  Branches. 

There  are  at  least  two  spinal  branches  from  each  ganglion,  one  superficial  and  larger, 
which  is  connected  to  the  outer  angle  of  the  ganglion  ;  the  other  deep  and  smaller, 
which  is  attached  to  its  posterior  surface  :  there  is  sometimes  a  third  filament  of  com- 
munication. Not  unfrequently  these  branches  unite  into  a  single  trunk,  before  reaching 
the  ganglion. 

I  regard  these  anastomotic  branches  (e  e),  between  the  spinal  nerves  and  the  ganglia 
of  the  sympathetic,  not  as  branches  furnished  by  the  ganglia  to  the  spinal  nerves,  nor 
simply  as  means  of  communication  between  one  and  the  other,  but  rather  as  branches 
of  origin  of  the  sympathetic  :  this,  indeed,  is  clearly  demonstrated  by  the  arrangement 
of  these  spinal  branches  of  the  sympathetic,  which  are  always  proportioned  to  the  size 
of  the  ganglia  from  which  they  arise.  In  general,  each  ganglion  communicates  only 
with  the  corresponding  spinal  nerve  ;  not  unfrequently,  however,  a  ganglion  receives  a 
twig  from  the  intercostal  nerve  immediately  below  it.* 

The  branches  of  conununication  from  the  dorsal  nerves  to  the  thoracic  ganglia  of  the 
sympathetic  are  horizontal,  or,  rather,  they  are  inclined  obliquely  downward  and  inward, 
excepting  those  which  ascend  to  the  first  thoracic  ganglion,  and  those  which  descend  to 
join  the  last  thoracic  ganglion.  These  branches  are  white,  like  the  nerves  of  the  cere- 
bro-spinal  system,  and  not  gray,  like  the  ganglionic  nerves.  On  examining  their  ulti- 
mate distribution  in  the  sympathetic  ganglia,  and  their  connexions  with  the  dorsal  and 
intercostal  nerves,  after  the  parts  have  been  macerated,  first  in  diluted  nitric  acid  and 
then  in  water,  it  is  seen  that  these  branches  are  evidently  reflected  funiculi  of  the  spi- 
nal nerves  ;  and  that  the  nerves,  immediately  after  having  given  off  these  branches,  are 
proportionally  diminished  in  size  ;  that,  having  reached  the  ganglia,  the  communicating 
branches  divide  into  filaments,  of  which  some  ascend,  and  may  be  traced  upon  the  trunk 
of  the  sympathetic  above  the  ganglion,  and  appear  to  be  continuous  with  the  descending 
filaments  derived  from  the  spinal  nerve  above,  while  the  others  descend  to  pass  upon  the 
portion  of  the  sympathetic  trunk  below  the  ganglion  ;  and,  lastly,  that  these  white  fila- 
ments run  upon  the  surface  of  the  sympathetic,  and  contrast  with  the  gray  colour  of  the 
central  portion  of  that  nerve. 

The  Internal,  or  Aortic  and  Splanchnic  Branches. 

The  internal  branches  of  the  first  five  or  six  thoracic  ganglia  are  exclusively  intended  fo~ 
the  aorta ;  some  of  them  appear  to  enter  the  pulmonary  plexus. 

Some  of  the  internal  branches  of  the  last  six  thoracic  ganglia  are  intended  for  the  aorta, 
and  the  remainder,  which  are  the  principal,  unite  to  form  the  splanchnic  nerves  or  nerves 
of  the  abdominal  viscera.     I  have  never  seen  any  of  them  pass  to  the  oesophagus. 

The  Aortic  Branches. — The  aortic  branches  consist  of  very  small  filaments,  of  which 
two  or  three  proceed  from  each  ganglion.  They  accompany  the  intercostal  arteries, 
around  which  they  form  small  plexuses.  These  filaments  are  much  longer  on  the  right 
than  on  the  left  side,  on  account  of  the  position  of  the  aorta  ;  they  pass,  some  in  front 
and  others  behind  that  vessel,  upon  which  it  soon  becomes  impossible  to  follow  them. 
The  aortic  branch  from  the  fourth  thoracic  ganglion  is  the  only  one  of  any  considerable 
size  ;  it  appears  to  be  shared  between  the  aorta  and  the  pulmonary  plexus.  A  number 
of  these  aortic  filaments  sometimes  converge  towards  certain  small  knots  or  ganglia, 
which  are  arranged  in  front  or  along  the  sides  of  the  aorta,  and  give  off  a  number  of  fil- 
aments. 

The  first  thoraci©  ganglion  sends  some  twigs  to  the  cardiac  plexuses  ;  and  not  unfre- 

*  In  one  subject  I  found  a  yery  remarkable  disposition  of  the  branches  for  the  four  inferior  thoracic  gang-lia. 
Some  small  twigs  from  these  four  ganglia  terminated  in  a  minute  gangliform  structure,  which  gave  off  the 
branches  to  the  spinal  nerves.  It  will  be  seen  that  the  same  arrangement  frequently  occurs  in  the  lumbal 
region. 


THE    SPLANCHNIC    NERVES.  ISIJJJ 

quently  the  inferior  cardiac  nerve  proceeds  from  this  ganglion.  Some  filaments  from  the 
same  ganglion  are  distributed  to  the  lower  part  of  the  longus  colli  muscle. 

Lobstein  (De  Nerco  Magna  Sympathetica,  p.  19)  describes  a  very  delicate  filament  from 
this  ganglion,  which  perforates  the  anterior  common  vertebral  ligament,  and  enters  the 
substance  of  one  of  the  vertebrae.  A  similar  filament  appears  to  me  to  be  given  off  by 
all  the  cervical,  thoracic,  lumbar,  and  sacral  s)Tnpathetic  ganglia.  The  vertebrae  like  the 
other  bones,  are  provided  with  nerves,  which  are  overlooked  in  a  hasty  examination 
from  their  excessive  tenuity. 

The  Splanchnic  Branches. — ^These  constitute  the  splanchnic  nerves,  which  require  a 
separate  description. 

The  Splanchnic  Jferves. 

The  splanchnic  nerves  are  divided  into  the  great  splanchnic  and  the  small  splanchnic 
or  renal  * 

The  Great  Splanchnic  Nerve. — ^The  great  splanchnic  is  a  white  nerve,  and  has  no  re- 
semblance to  the  ganglionic  nerves.  It  is  formed  in  the  following  manner :  a  thick 
branch  derived  from  the  sixth  and  seventh  thoracic  ganglia,  sometimes  also  from  the 
fifth,  and  even  from  the  fourth  ganglion  (see  fig.  302),  passes  downward  and  inward  upon 
the  side  of  the  dorsal  vertebrae  :  this  branch  is  joined  by  a  series  of  three  or  four  smaller 
branches  given  off  not  only  from  the  succeeding  thoracic  ganglia,  but  also  from  the  com- 
municating cords  between  them ;  these  branches  {g  g)  are  parallel  to  each  other,  and 
pass  obliquely  downward  and  inward.  The  eleventh  and  twelfth  thoracic  ganglia  never 
assist  in  the  formation  of  the  great  splanchnic  nerve. 

The  branches  just  mentioned  unite  on  each  side  to  constitute  the  great  splanchnic 
nerves,  which  have  the  same  relation  to  the  thoracic  ganglia  that  the  cardiac  nerves 
have  to  the  cervical  ganglia :  it  is  important  to  remark  that  the  ganglionic  nerves  of  the 
thoracic  viscera  are  derived  from  the  cervical  ganglia  of  the  sympathetic,  and  that  the 
ganglionic  nerves  of  the  abdominal  viscera  are  given  off  from  the  thoracic  ganglia. 

In  general,  the  great  splanchnic  nerve  arises  by  four  roots ;  but  not  unfrequently  it 
arises  only  by  two,  which  then  represent  the  four  origins. 

If,  after  having  macerated  the  parts  in  diluted  nitric  acid,  an  attempt  be  made  to  de- 
termine exactly  the  highest  point  from  which  the  great  splanchnic  nerve  originates,  it 
will  be  seen  that  the  white  filaments  of  which  this  nerve  is  composed  are  already  dis- 
tinct opposite  the  third  thoracic  ganglion,  and,  moreover,  that  they  are  merely  in  contact 
with  the  trunk  of  the  sympathetic  and  with  the  ganglia,  and  are  continuous  with  the 
coomiunicating  branches  from  the  spinal  nerves.  Anatomy,  therefore,  most  clearly 
proves  that  the  splanchnic  nerve  is  continuous  with  the  spinal  nerves. 

Thus  formed  and  completed  opposite  to  the  eleventh  rib,  the  great  splanchnic  nerve 
passes  downward  and  inward  in  front  of  the  vertebral  column ;  it  becomes  flattened  and' 
widened,  perforates  the  diaphragm,  the  fibres  of  which  separate  to  allow  it  to  pass 
through,  and  immediately  terminates  in  the  semilunar  ganglion  {x).  An  oUve-shaped 
ganglion  is  not  unfrequently  found  upon  the  great  splanchnic,  at  a  short  distance  before 
the  nerve  passes  through  the  diaphragm.* 

The  Small  Splanchnic,  or  Renal  Nerves.-^  think  it  proper  to  include  in  the  same  de- 
scription the  lesser  splanchnic  nerve  of  authors,  and  the  posterior  renal  nerves  of  Walter, 
the  distinction  between  these  nerves  appearing  to  me  to  be  quite  arbitrary.  They  are 
two,  ani  sometimes  three  in  number.  The  highest  is  named  the  small  splanchnic  (h) ;  it 
arises  from  the  eleventh  thoracic  ganglion,  and  sometimes  from  both  the  tenth  and  the 
eleventh.  The  lowest,  which  is  the  renal  nerve  of  authors,  is  larger  than  the  preceding, 
and  is  derived  from  the  twelfth  thoracic  ganglion  (f) :  it  often  gives  off  a  small  fileunent 
to  the  first  lumbar  ganglion,  and  in  a  great  number  of  cases  this  is  the  only  means  of 
communication  between  the  thoracic  and  the  lumbar  ganglia  of  the  sympathetic.  In 
such  a  case,  the  series  of  ganglia  is  said  to  be  interrupted ;  but  a  complete  interruption 
never  exists. 

The  small  splanchnic  or  renal  nerves  exactly  resemble  the  separate  or  single  origins 
of  the  great  splanchnic,  with  which  they  form  a  continuous  series.  They  arise  in  the 
same  manner,  from  the  two  or  three  inferior  thoracic  ganglia.  They  pass  inward  and 
downward,  parallel  to  and  on  the  outer  side  of  the  great  splanchnic,  perforate  the  crus 
of  the  diaphragm  either  to  the  outer  side  of  or  at  the  same  point  as  the  great  nerve,  and 
enter  the  renal  and  aortic  plexuses ;  they  are  often  shared  between  these  two  plexuses 
and  the  great  splanchnic  nerve.  The  highest  of  the  small  splanchnic  nerves  rather  fre- 
quently anastomoses  with  the  great  splanchnic,  or  even  becomes  entirely  blended  with  it.t 

*  Lobstein  has  recorded  a  case  (p.  2)  mwhich  this  unusual  ganglion  on  the  great  splanchnic  was  of  a  semi- 
lunar shape,  and  gave  off,  from  its  convex  side,  seven  or  eight  slender  filaments,  which  accompanied  the  aorta 
and  were  all  lost  in  the  diaphragm  ;  he  has  also  mentioned  another  case,  in  which  three  filaments  arose  from 
this  ganglion,  two  going  to  the  solar  plexus,  and  the  third  to  the  mesenteric  plexus. 

t  Among  the  numerous  varieties  which  I  have  observed  in  the  formation  of  the  small  splanchnic  nerves,  I 
would  especially  notice  the  following:  a  twig  from  the  eleventh  thoracic  ganglion,  and  one  from  the  great 
splanchnic  nerve,  terminated  in  a  small  ganglion ;  from  this  ganglion  were  given  oflf  several  filaments  that 
were  lost  ni)on  the  aorta,  and  also  a  small  cord  which  joined  with  a  twig  from  the  twelfth  thoracic  ganglion, 
and  was  di.itributed  in  the  ordinary  manner. 

5R 


866  NEUROLOGY. 

The  Visceral  Ganglia  and  Plexuses  in  the  Abdomen. 

As  the  semilunar  ganglia  and  the  visceral  plexuses  in  the  abdomen  form  the  continuation 
of  the  splanchnic  nerves,  it  is  not  only  theoretically,  but  practically  convenient  to  enter 
upon  their  description  now. 

The  central  point  of  all  these  ganglia  and  plexuses  is  situated  at  the  epigastrium,  and 
is  formed  by  a  ganglionic  plexus,  named  the  solar  or  epigastric  plexus. 

The  Solar  or  Epigastric  Plexus. 

The  solar  plexus  (opposite  x,fig.  302)  is  formed  by  an  uninterrupted  series  of  ganglia, 
extending  from  the  great  splanchnic  nerve  of  the  one  side  to  its  fellow  of  the  opposite  side. 
From  this  point  as  from  a  centre  proceed  a  great  number  of  branches,  which  have  been 
compared  to  the  rays  of  the  sun,  and  hence  the  term  solar  plexus. 

This  solar  plexus,  which  is  regarded  by  physiologists  as  the  centre  of  the  nervous  sys- 
tem of  nutritive  life,  is  deeply  seated  in  the  epigastric  region,  and  might  therefore  be 
called  the  epigastric  nervous  centre ;  it  is  situated  in  the  median  line,  in  front  of  the  aorta, 
around  the  coeliac  axis,  and  above  the  pancreas  ;  it  is  bounded  on  each  side  by  the  supra- 
renal capsules,  and  is  of  too  irregular  a  shape  to  be  clearly  defined.  The  ganglia  of 
which  it  is  composed,  the  solar  ganglia,  are  as  irregular  and  variable  as  the  plexus  it- 
self They  consist  of  thick  and  swollen  cords,  or  ganglionic  arches  or  circles,  arranged 
in  a  network,  in  the  meshes  of  which  are  found  some  lymphatic  glands  easily  distin- 
guishable from  the  nervous  ganglia  and  cords.  Anatomists,  in  general,  describe  only  the 
two  extreme  ganglia  of  the  solar  plexus,  in  which  the  great  splanchnic  nerves  terminate ; 
these  are  the  semilunar  ganglia  (x),  so  called  from  their  shape,  but  which  are  subject  to 
much  variety  both  in  form  and  size.  Their  convex  border,  which  is  turned  downward, 
is  divided  into  several  teeth,  from  each  of  which  a  pencil  of  nerves  is  given  off;  a  great 
number  of  filaments  are  also  given  off  from  their  concave  border,  which  is  directed  up- 
ward. These  ganglia  are  situated  close  to  the  supra-renal  capsules ;  they  are  often 
without  any  regular  form,  and,  as  it  were,  divided  into  fragments. 

A  single  glance  at  the  solar  plexus  will  suffice  to  convince  us  of  the  impossibility  of 
extirpating  it,  as  some  experimenters  pretend  to  have  done,  in  living  animals. 

The  great  splanchnic  nerve  of  each  side  (g),  a  part  of  the  small  splanchnic  nerves  (A), 
and  the  right  pneumogastric  nerve  (j)'),  end  in  the  solar  plexus.  I  have  also  seen  the 
right  phrenic  enter  this  plexus. 

From  it,  as  from  a  centre,  plexuses  are  given  off  for  all  the  arteries  arising  from  the 
fore  part  of  the  aorta,  and  also  for  the  renal  and  spermatic  arteries.  The  plexuses  for 
the  renal  arteries  and  the  inferior  mesenteric  artery  are  completed  by  the  visceral  nerves 
derived  directly  from  the  lumbar  ganglia.  There  are  two  diaphragmatic  plexuses,  a  coeliac 
plexus,  a  superior  and  an  inferior  mesenteric  plexus,  renal  plexuses,  spermatic  or  ova- 
rian plexuses,  and  supra-renal  plexuses. 

All  the  nerves  given  off  from  the  solar  ganglia  are  gray,  and  very  small ;  they  are  al- 
ways plexiform,  and  are  generally  strong  on  account  of  the  thickness  of  their  neurilemma. 

The  Diaphragmatic  and  Supra-renal  Plexuses. 

The  diaphragmatic  or  phrenic  plexuses  are  small ;  they  are  given  off  from  the  upper  part 
of  the  solar  plexus,  and  reach  the  phrenic  arteries,  with  which  they  enter  the  diaphragm ; 
they  at  first  lie  beneath  the  peritoneum,  but  afterward  dip  into  the  substance  of  the  fleshy 
fibres  of  the  muscle,  and  do  not  exactly  follow  the  course  of  the  vessels.  In  some  cases 
I  have  been  able  to  ascertain  that  they  anastomose  with  the  filaments  of  the  phrenic 
nerve  :  they  always  run  in  nearly  the  same  direction. 

The  diaphragmatic  plexus  of  the  right  side  is  larger  than  that  of  the  left.  I  have  seen 
two  ganglia,  upon  the  right  cms  of  the  diaphragm,  which  formed  the  origin  of  the  right 
diaphragmatic  plexus  and  of  some  hepatic  nerves. 

I  arrange  the  plexuses  of  the  supra-renal  bodies  with  the  preceding,  because  they  have 
so  many  relations  with  them.  They  arise  directly  from  the  semilunar  ganglia,  by  two 
very  delicate  pencils  of  nerves,  which  reach  the  back  of  the  supra-renal  arteries,  and  are 
lost  in  the  substance  of  the  supra-renal  bodies.  Several  filaments  from  the  diaphrag- 
matic plexuses  join  them,  passing  in  front  of  the  arteries.  The  supra-renal  plexuses  are 
large  in  proportion  to  the  size  of  the  organs  they  supply. 

The  Cceliac  Plexus. 
The  coeliac  plexus  is  one  of  the  principal  divisions  of  the  solar  plexus,  of  which  it  is 
•  the  immediate  prolongation,  so  that  it  is  almost  impossible  to  distinguish  one  from  the 
■  other  ;  it  surrounds  the  coeliac  axis,  and  immediately  divides,  like  it,  into  three  plexuses, 
.the  coronary  of  the  stomach,  the  hepatic,  and  the  splenic. 

The  Coronary  Plexus  of  the  Stomach. — This  is  given  off  from  the  upper  part  of  the  solar 

t  plexus ;  it  receives  some  filaments  from  the  right  pneumogastric,  before  that  nerve  joins 

;.  the  solar  plexus ;  of  these  filaments,  some  ramify  upon  the  cardia,  while  the  remainder 

follow  the  coronary  artery  along  the  lesser  curvature  of  the  stomach,  and  anastomose 

■jwith  the  pyloric  filaments  of  the  hepatic  plexus.     It  follows,  therefore,  that  the  stomach 


THE    SUPERIOR   MESENTERIC    PLEXUS.  867 

is  principally  supplied  by  the  pneuraogastric  nerve.  The  filaments  from  the  coronary 
plexus  of  the  stomach,  as  well  as  those  of  the  pneumogastric  nerve,  after  having  run  for 
some  distance  beneath  the  peritoneum,  perforate  the  muscular  coat  of  the  stomach,  and 
appear  to  be  partly  lost  in  it  and  partly  in  the  mucous  membrane. 

The  hepatic  plexus  is  of  very  considerable  size,  and  might  be  divided,  after  the  example 
of  Lobstein,  into  an  anterior  and  a  posterior  plexus.  The  anterior  accompanies  the  hepat 
ic  artery,  and  is  formed  by  some  twigs  from  the  right  pneumogastric,  and  by  seven  or 
eight  large  gray,  cylindrical  filaments  from  the  left  semilunar  ganglion,  which  are  joined 
by  two  or  three  branches  from  the  right  semilunar  ganglion. 

The  posterior  hepatic  plexus  accompanies  the  vena  portae,  and  is  derived  almost  entirely 
from  the  right  semilunar  ganglion ;  it  is  also  composed  of  grayish,  thick,  cylindrical  cords. 
I  would  especially  notice  one  cord,  which  is  remarkable  both  from  its  size  and  its  course  ; 
it  arises  directly  from  the  solar  ganglion  of  the  right  side,  passes  in  a  horizontal  and 
curved  direction  to  reach  the  gastro-hepatic  omentum,  and  continues  horizontally  be- 
tween the  layers  of  that  omentum,  in  front  of  the  lobulus  Spigelii ;  it  then  ascends  to 
the  transverse  fissure  of  the  liver,  becomes  situated  beneath  the  vena  portae,  and  may 
be  traced  along  that  vein  into  the  interior  of  the  liver.  I  have  seen  this  great  he- 
patic branch  come  directly  from  two  ganglia  situated  upon  the  right  crus  of  the  dia- 
phragm. 

Before  reaching  the  liver,  the  hepatic  plexus  gives  off  a  secondary  plexus  of  consider- 
able size,  around  the  right  gastro-epiploic  artery,  the  right  gastro-epiploic  plexus ;  it  is 
considerably  augmented  by  filaments  which  are  derived  immediately  from  the  solar 
plexus,  and  perforate  the  pancreas. 

The  hepatic  plexus  also  furnishes  branches  to  the  pylorus  and  the  lesser  curvature  of 
the  stomach,  to  the  pancreas,  to  the  great  curvature  of  the  stomach,  and  to  the  great 
omentum.  The  pylorus,  therefore,  and  the  great  curvature  of  the  stomach,  are  supplied 
almost  exclusively  by  the  hepatic  plexus.* 

The  hepatic  plexus  likewise  gives  off  a  small  cystic  plexus,  which  is  easily  seen  beneath 
the  peritoneum,  surrounding  the  cystic  artery  as  far  as  the  gall-bladder. 

Diminished  in  size,  from  having  given  off  a  series  of  branches  and  plexuses,  the  he- 
patic plexus  gains  the  transverse  fissure  of  the  liver,  divides  like  the  hepatic  artery  and 
vena  portae,  and  may  be  traced  for  some  distance  in  the  capsule  of  Glisson. 

All  the  nerves  of  the  liver  are  gray,  but  very  strong. 

The  Splenic  and  Pancreatic  Plexuses. — The  splenic  plexus  is  not  so  remarkable  for  the 
number  as  for  the  size  of  the  filaments  of  which  it  is  composed ;  it  surrounds  the  splenic 
artery,  furnishes  some  twigs  to  the  pancreas,  and  it  also  gives  off  the  left  gastro-epiploic 
plexus,  which  is  smaller  than  the  right,  is  situated  upon  the  great  curvature  of  the  stom- 
ach, and  supplies  that  organ  and  the  great  omentum.  The  splenic  plexus  also  gives  off 
nervous  filaments  to  the  great  cul-de-sac  of  the  stomach,  and  being  thus  very  much  di- 
minished in  size,  reaches  the  hilus  of  the  spleen,  within  which  organ  it  can  be  easily  tra- 
ced in  man,  and  still  more  easily  in  the  larger  animals,  along  the  ramifications  of  the 
bloodvessels. 

These  nerves  are  gray,  and  very  strong.  The  numerous  filaments  which  pass  to  the 
pancreas,  and  form  a  plexus  around  its  arteries,  constitute  the  pancreatic  plexus,  which 
may  be  regarded  as  a  dependance  of  the  splenic  plexus. 

The  Superior  Mesenteric  Plexus. 

The  superior  mesenteric  plexus,  which  may  be  regarded  as  the  lower  division  of  the  bi- 
furcation of  the  epigastric  plexus,  is  the  largest  of  all  the  abdominal  plexuses  ;  it  sur- 
rounds the  superior  mesenteric  artery,  forming  an  extremely  thick  plexiform  sheath  for 
it ;  it  passes  below  the  pancreas,  enters  the  substance  of  the  mesentery  {w)  with  the 
artery,  and  divides,  like  that  vessel,  into  a  great  number  of  secondary  plexuses,  which 
are  distributed  to  all  the  parts  supplied  by  the  artery,  namely,  to  the  whole  of  the  small 
intestine,  excepting  the  duodenum,  and  to  the  right  portion  of  the  great  intestine. 

Without  entering  into  tedious  and  useless  details,  I  shall  content  myself  with  a  few 
remarks  upon  the  general  distribution  of  these  nerves. 

The  mesenteric  nerves  are  remarkable  for  their  length,  their  number,  and  their 
strength.  I  am  certain  that  their  neurilemmatic  sheath  is  proportionally  much  thicker 
than  that  of  other  nerves.  They  are  placed  at  variable  distances  from  the  vessels,  and 
proceed  in  a  straight  line  in  the  substance  of  the  mesentery  towards  the  intestine,  with- 
out giving  off  any  filaments :  at  a  short  distance  from  the  concave  border  of  the  intes- 
tine, they  either  pass  directly  to  the  bowel,  or  else  they  anastomose  at  an  angle  or  in 
an  arch  ;  from  the  convexity  of  these  anastomotic  arches  the  filaments  for  the  intestine 
are  given  off. 

There  is  never  more  than  one  series  of  anastomotic  nervous  arches  in  the  mesentery, 
whatever  may  be  the  number  of  rows  of  vascular  arches  ;  the  single  nervous  arch  al- 

*  The  cardia  and  the  lesser  curvature  of  the  stomach  are  the  parts  which  are  the  most  abundantly  provided 
with  nerves.    The  pylorus,  to  which  we  attribute  such  great  .".ensibility,  has  incomparably  fewer. 


NEUROLOGY. 


ways  cdiTesponds  fb  the  vascular  arch  nearest  to  the  intestine :  the  filaments  ■which 
proceed  from  it  are  exceefl'ngly  minute.* 

The  nervous  filaments  pt  netrate  the  intestine  by  its  adherent  border,  run  for  some 
time  between  the  serous  ai  .d  muscular  coats,  perforate  the  latter,  to  which  they  give 
some  twigs,  then  spread  out  lO  the  fibrous  coat,  and  finally  terminate  in  the  mucous  mem- 
brane 

The  Inferior  Mesenteric  Plexus. 

The  inferior  mesenterf  pit  ms  (n)  is  formed  by  some  twigs  from  the  epigastric  plexus, 
:r,  rather,  from  the  sup(  ric;  mesenteric  plexus,  with  which  it  is  continuous  on  the  front 
lif  the  abdominal  aorta ;  ai  l,  secondly,  by  some  branches  from  the  lumbar  sympathetic 
4;anglia,  which,  as  hereai'^tr  stated,  constitute  the  lumbo-aortic  plexus.  The  meshes  of 
..he  inferior  mesenteric  plexus  are  by  no  means  so  close  as  those  of  the  superior  mesen- 
teric plexus. 

The  inferior  mesenteric  plexus,  like  the  artery  by  which  it  is  supported,  supplies  the 
Left  half  of  the  transverse  arch  of  the  colon,  the  descending  colon,  the  sigmoid  flexure, 
and  the  rectum :  of  its  filaments,  those  which  accompany  the  left  colic  arteries  are  re- 
markable for  their  tenuity,  their  length,  and  for  giving  no  branches  in  their  course  to 
the  intestine.  I  would  particularly  notice  the  twig  which  accompanies  the  left  superior 
colic  artery.  It  is  not  uninteresting  to  remark,  that  these  nerves  are  more  numerous  in 
the  iliac  meso-colon,  which  supports  the  sigmoid  flexure,  than  at  any  other  point. 

The  inferior  mesenteric  plexus,  thus  diminished  by  having  given  off  other  smaller 
plexuses,  terminates,  like  the  inferior  mesenteric  artery,  by  bifurcating ;  the  two  divis- 
ions of  this  bifurcation  are  called  the  hemorrhoidal  plexuses ;  they  surround  the  two  divis- 
ions of  the  artery,  viz.,  the  superior  hemorrhoidal  arteries,  and  terminate  partly  in  the 
hypo-gastric  plexus  and  partly  in  the  rectum. 

The  Renal  and  Spermatic,  or  Ovarian  Plexuses. 

The  renal  plexuses  are  extremely  complicated :  they  are  formed  by  branches  from  the 
solar  plexus,  and  by  the  two  or  three  small  splanchnic  or  renal  nerves,  and  terminate 
almost  exclusively  by  surrounding  the  renal  artery. 

The  two  spermatic  plexuses  in  the  male,  and  ovarian  plexuses  in  the  female,  are  derived 
principally  from  the  renal  plexuses.  The  spermatic  plexuses  are  destined  exclusively  for 
the  testicles ;  the  ovarian  plexuses,  like  the  arteries  of  the  same  name,  are  distributed 
both  to  the  ovaries  and  the  uterus.  The  intimate  connexions  between  the  nerves  of  the 
kidneys  and  testicles  in  the  male,  and  those  of  the  kidneys,  ovaries,  and  uterus  in  the 
female,  deserve  the  most  particular  attention  of  anatomists. 

The  Lumbar  Portion  of  the  Sympathetic  System. 

The  lumhar  portion  of  the  trunk  of  the  sympathetic  {II,  fig-  302)  is  situated  in  front  of  the 
vertebral  column,  along  the  inner  border  of  the  psoas  muscle.  The  ganglia  of  this  re- 
gion are  therefore  nearer  the  median  line  than  the  thoracic  ganglia ;  but  the  inferior  lum- 
bar ganglia  not  unfrequently  deviate  from  their  ordinary  position,  and  approach  the  lum- 
bar nerves  as  these  emerge  from  the  spinal  canal :  in  this  case,  they  are  concealed  by  the 
psoas  muscle.  The  lumbar  ganglia  of  the  sympathetic  vary  much  in  size  ;  some  of  them 
are  so  small  that  they  would  escape  notice,  if  their  grayish  colour  did  not  distinguish  them 
from  the  rest  of  the  trunk  of  the  sympathetic. 

The  number  of  these  ganglia  is  also  variable ;  there  are  rarely  more  than  four. 
Two  or  three  ganglia  are  often  blended  into  a  gangliform  cord ;  this  fusion  may  be  easily 
recognised  by  the  arrangement  of  the  communicating  filaments  between  it  and  the  lum- 
bar spinal  nerves. 

In  one  subject,  the  twelfth  thoracic  ganglion  on  the  right  side  was  blended  with  the 
first  lumbar  ganglion :  a  small  filament,  corresponding  in  length  to  the  thickness  of  two 
vertebrae,  established  a  communication  between  this  ganglion  aiid  a  large  gangliform 
cord,  which  represented  by  itself  the  four  inferior  lumbar  ganglia.  On  the  left  side,  the 
second  and  third  lumbar  ganglia  were  united,  and  the  fifth  was  blended  with  the  first 
sacral.  This  fusion  of  the  lumbar  ganglia  almost  constantly  exists,  and  it  establishes  a 
close  analogy  between  the  lumbar  portion  of  the  sympathetic  and  the  cervical  portion, 
which,  as  we  have  already  seen,  has  only  three,  and  frequently  only  two  ganglia.  It 
proves  that  the  superior  cervical  ganglion  may  be  regarded  as  representing  five  superior 
cervical  ganglia  and  the  ganglia  corresponding  to  the  two  sets  of  cranial  nerves,  and 
that  the  inferior  cervical  ganglion  may  be  viewed  as  the  representative  of  two  lower  cer- 
vical ganglia,  when  the  middle  ganglion  is  wanting. 

Moreover,  the  trunk  of  the  sympathetic  is  not  unfrequently  interrupted  either  between 
the  twelfth  thoracic  and  the  first  lumbar  ganglion,  or  between  the  last  lumbar  and  the 

'  In  one  case  I  found  a  very  remarkable  anastomosis.  Four  filaments,  proceeding  from  four  opposite  points, 
converged  towards  a  common  centre  ;  but,  as  they  were  about  to  cross,  they  diverged  from  one  another  so  as 
to  intercept  a  lozenge-shaped  space.  Two  of  these  might  lie  regarded  as  filaments  of  origin,  and  the  other 
two  ;i5  terminating  filaments 


LUMBAR   PORTION    OF    THE    SYMPATHETIC  SYSTEM.  869 

first  sacral  ganglion :  this  interruption  is,  however,  more  apparent  than  real,  for.  as  I 
have  already  stated,  the  continuity  between  the  twelfth  thoracic  and  the  first  lumbar 
ganglion  is  always  established  by  means  of  a  small  twig  from  the  renal  nerve. 

The  branches  of  the  lumbar  ganglia  may  be  divided  into  the  branches  of  communi- 
cation between  the  ganglia  ;  the  external  branches,  and  the  internal  branches :  besides 
these,  there  are  some  small  and  very  delicate  filaments,  which  enter  the  bodies  of  the 
yertebrse. 

The  Communicating  Branches  between  the  Ganglia. 

These  communicating  branches  consist  of  one  or  more  white  cords  extending  between 
every  two  ganglia ;  they  scarcely  ever  have  the  gray  appearance  and  ganglionic  struc- 
ture usually  found  in  similar  branches  of  conununication :  the  communicating  filament 
between  the  fourth  and  fifth  lumbar  ganglion  is  often  wanting. 

The  External  Branches. 

These  are  the  branches  (at  d)  which  communicate  with  the  lumbar  nerves.  I  c6n- 
ceive  that  they  are  furnished  by  the  lumbar  spinal  nerves  to  the  lumbar  ganglia  of  the 
sympathetic.  There  are  generally  two,  but  sometimes  three  for  each  ganglion ;  they 
arise  from  the  anterior  branches  of  the  several  lumbar  nerves,  as  they  emerge  from  the 
inter- vertebral  foramina  ;*  they  accompany  the  lumbar  arteries,  along  the  grooves  upon 
the  bodies  of  the  lumbar  vertebrae,  and  terminate  in  the  corresponding  ganglia ;  they  are 
usually  directed  obliquely  downward. 

In  general,  each  ganglion  receives  branches  not  only  from  the  corresponding  lumbar 
nerve,  but  also  from  the  nerve  next  above  it.  Thus,  two  branches  end  in  the  second 
lumbar  ganglion,  one  from  the  first,  and  another  from  the  second  lumbar  nerve ;  the 
third  ganglion  receives  filaments  from  the  second  and  third  lumbar  nerves  ;  when  one 
ganglion  is  wanting,  its  place  is  supplied  by  the  next,  which  receives  its  own  proper 
branches,  and  also  those  belonging  to  the  absent  ganglion.  One  ganglion  not  unfrequent 
ly  communicates  with  three  lumbar  nerves. 

When  several  ganglia  are  united  into  one,  it  is  easy  to  conceive  that  this  single  gan- 
glion must  receive  aU  the  filaments  corresponding  to  those  ganglia.  It  is  also  easy  to 
understand  that  these  filaments  must  be  directed  more  or  less  obliquely  either  upward 
or  downward,  and  that  they  will  correspond  in  length  to  the  distance  between  the  lum- 
bar nerves  and  the  single  ganglion,  the  superior  filaments  being  directed  downward, 
and  the  inferior  filaments  upward. 

A  very  remarkable  condition  of  the  branches  of  communication  between  the  lumbar 
nerves  and  the  sympathetic  ganglia  consists  in  the  existence  of  certain  ganglia  or  swell- 
ings upon  them ;  and  the  ahnost  indefinite  anomalies  observed  in  this  particular  are  no 
less  remarkable.  I  have  found  as  many  as  three  ganglionic  nodules  upon  the  same 
communicating  branch:  sometimes,  when  the  two  or  three  communicating  branches 
reach  the  side  of  a  vertebra,  they  unite  in  a  ganglion,  from  which  two  or  three  other 
branches  are  given  off  to  the  proper  sympathetic  ganglion,  t 

Moreover,  these  ganglia,  like  all  the  irregular  ganglia,  rarely  present  that  peculiar 
character  which  is  common  to  the  regular  ganglia,  namely,  that  of  forming  a  centre  in 
which  a  certain  number  of  filaments  end,  and  from  which  others  are  given  off. 

The  Internal,  or  Aortic  and  Splanchnic  Branches. 
The  internal  branches  from  the  lumbar  ganglia  are  the  aortic  and  the  lumbar  splanchnic 
branches,  and  form  a  continuous  and  uninterrupted  series  with  the  aortic  and  splanchnic 
branches  from  the  thoracic  ganglia ;  so  that  the  internal  branches  from  the  first  (/)  and 
sometimes  from  the  second  lumbar  ganglion  join  the  branches  from  the  eleventh  and 
twelfth  thoracic  ganglia,  to  form  a  small  splanchnic  nerve,  which  is  shared  between  the 
solar  and  the  renal  plexus.  Some  small  gangliform  nodules  are  occasionally  found  upon 
the  course  of  these  branches,  among  which  are  some  very  delicate  filaments,  which  evi- 
dently pass  into  the  bodies  of  the  lumbar  vertebrae.  All  these  internal  branches  assist 
in  the  formation  of  the  lumbar  splanchnic,  or  pelvic  visceral  nerves. 

The  Lumbar  Splanchnic  Serves  and  the  Visceral  Plexuses  in  the  Pelvis. 

The  lumbar  splanchnic  nerves  (at  k)  pass  inward  in  front  of  the  aorta,  below  the  su- 
perior mesenteric  artery,  and  anastomose  with  each  other  and  with  those  of  the  opposite 
side  to  form  a  very  complicated  plexus,  which  is  completed  by  a  very  considerable  pro- 
longation from  the  superior  mesenteric  plexus. 

This  plexus  (n),  which  may  be  called  the  lumbo-aortic  plexus,  surrounds  all  that  por- 
tion of  the  aorta  which  is  included  between  the  superior  and  inferior  mesenteric  arteries ; 
in  the  intervals  between  the  nervous  filaments  are  found  lymphatic  glands,  which  should 
be  carefully  distinguished  from  some  nervous  ganglia  which  form  part  of  the  plexus. 

The  lumbo-aortic  plexus  is  bifurcated  below ;  one  portion  of  it  passes  upon  the  infe- 

*  These  communicating  branches  frequently  arise  in  the  substance  of  the  psoas  muscle  from  twigs  derived 
from  the  lumbar  plexus. 

f  This  dispositiou  is  well  seen  in  the  beautiful  plate  of  the  sympathetic  published  by  M.  Manec. 


NEUROLOGY. 

rior  mesenteric  artery  to  constitute  the  greater  part  of  the  inferior  mesenteric  plexiis 
(below  n) ;  while  the  other  portion  descends  upon  the  aorta,  and  even  a  little  below  the 
bifurcation  of  that  vessel,  and  ends  between  the  common  iliac  arteries,  in  front  of  the 
sacro-vertebral  angle,  from  which  it  is  separated  by  the  common  iliac  veins.  Some  fila- 
ments are  prolonged  around  the  common  iliac  and  the  external  and  internal  iliac  arter- 
ies and  their  branches. 

The  aortic  portion  of  the  lumbo-aortic  plexus  bifurcates  below  into  two  secondary  plex 
if  arm  cords,  one  right  and  the  other  left,  which  pass  downward  upon  the  sides  of  the  rec 
turn  and  bladder,  and  enter  the  right  and  left  hypogastric  plexuses,  which  are  almost 
entirely  formed  by  these  cords. 

The  Hypogastric  Plexuses. 

The  hypogastric  plexuses  (m)  are  among  the  great  plexuses  of  the  body ;  they  supply 
the  rectum  and  the  bladder  in  both  sexes,  and  also  the  prostate  and  testicle  in  the  male, 
and  the  vagina,  uterus,  and  Fallopian  tubes  in  the  female. 

There  are  two  hypogastric  plexuses,  one  on  the  right,  the  other  on  the  left  side.  They 
are  situated  upon  the  lateral  and  inferior  surfaces  of  the  rectum  and  bladder  in  the  male, 
and  of  the  rectum,  vagina,  and  bladder  in  the  female  ;  they  are  distinct  from  each  other, 
and  are  connected  not  by  median  anastomoses,  which  I  have  never  been  able  to  detect, 
but  through  the  lumbo-aortic  plexus,  by  the  bifurcation  and  spreading  out  of  which  they 
may  be  said  to  be  formed.  The  hypogastric  plexuses,  from  the  enlargement  and  areolar 
disposition  of  their  component  cords,  very  closely  resemble  the  solar  plexus. 

Each  plexus  is  formed  essentially  by  one  of  the  two  divisions  of  the  lumbo-aortic 
plexus  ;  it  is  also  joined  by  some  filaments  from  the  inferior  mesenteric  plexus,  by  some 
very  small  twigs  from,  the  sacral  ganglia,  among  which  those  derived  from  the  third  sa- 
cral ganglion  are  especially  remarkable ;  and,  lastly,  by  some  twigs  from  the  anterior 
branches  of  the  sacral  nerves  (see  Sacral  Nervks). 

Formed  by  a  combination  of  filaments  from  these  different  sources,  each  hypogastric 
plexus  gives  off  a  hemorrhoidal,  a  vescical,  a  vaginal,  a  uterine,  and  a  spermatic  or  ova- 
rian plexus  ;  all  of  these  plexuses,  like  the  hypogastric  plexus  itself,  are  found  on  each 
side  of  the  body. 

The  inferior  hemorrhoidal  plexuses  are  blended  with  the  superior  hemorrhoidal  plex- 
uses, which,  as  already  stated,  are  the  terminations  of  the  inferior  mesenteric  plexus ; 
they  pass  behind  and  in  front  of  the  rectum.  The  filaments  belonging  to  the  anterior 
branches  of  the  sacral  nerves  may  be  distinguished  from  those  belonging  to  the  sympa- 
thetic system  by  the  difference  in  the  colour  of  the  two  kinds  of  nerves. 

The  vesical  plexuses  are  composed  of  a  great  number  of  exceedingly  small  filaments. 
They  are  situated  upon  the  sides  of  the  posterior  fundus  (bas-fond)  of  the  bladder,  on  the 
outer  side  of  the  ureters,  and  are  divided  into  two  sets,  viz.,  ascending  vesical  nerves, 
which  pass  upward  upon  the  sides  of  the  bladder,  embrace  the  outer  and  inner  surfaces 
of  the  ureters,  and  ramify  upon  the  anterior  and  posterior  surfaces  of  the  bladder ;  and 
horizontal  vesical  nerves,  which  run  forward  upon  the  sides  of  the  fundus  of  the  bladder, 
externally  to  the  large  plexus  of  veins  found  in  that  situation,  and  spread  out  into  ex- 
tremely delicate  filaments,  of  which  some  enter  the  substance  of  the  bladder,  especially 
at  its  neck,  while  the  others,  in  considerable  numbers,  turn  round  the  prostate  gland, 
and  are  distributed  within  it ;  one  of  the  prostatic  filaments  may  be  traced  into  the  mem- 
branous portion  of  the  urethra. 

The  Plexuses  for  the  Vesictila  Seminales,  and  Vasa  Deferentia,  and  Testicles. — Some  of 
the  filaments  situated  on  the  inner  side  of  the  ureters  surround  the  vesiculae  seminales, 
and  are  lost  in  them  ;  these  are  very  small ;  two  or  three  remarkably  large  filaments  run 
upward  along  each  vas  deferens  ;  having  reached  the  inguinal  ring,  they  unite  with  the 
corresponding  spermatic  plexus,  which  is  a  production  of  the  renal  plexus,  and  descend 
to  the  testicle. 

The  branches  for  the  prostate,  vesiculae  seminales,  vasa  deferentia,  and  testicles,  are 
represented  in  the  female  by  the  utero-vaginal,  ovarian,  and  tubal  nerves. 

The  Uterine  Nerves. — Notwithstanding  the  figures  of  the  sympathetic  published  by 
Walter,  in  which  the  nerves  of  the  uterus  are  well  represented,  and  notwithstanding  the 
still  more  explicit  description  given  of  them  by  Hunter,  most  anatomists  continue  to  en- 
tertain doubts  regarding  the  existence  of  the  uterine  nerves.  Lobstein,  in  his  work  on 
the  Sympathetic,  published  in  1822,  even  denied  them  altogether ;  but  Tiedemann,  in  the 
same  year,  published  two  beautiful  figures,  representing  the  nerves  of  the  gravid  uterus.* 

The  uterine  nerves  are  derived  from  several  sources.  I  have  already  stated  that  the 
plexuses  surrounding  the  ovarian  arteries,  which  are  productions  of  the  renal  plexuses, 
are  distributed,  like  the  vessels  by  which  they  are  supported,  both  to  the  uterus  and  the 
ovaries. 

It  appears  to  me  that  the  ovarian  nerves  and  vessels  have  a  similar  arrangement,  that 
is  to  say,  that  the  uterine  branches  derived  from  the  ovarian  plexuses  are  larger  than  the 
ovarian  nerves  properly  so  called. 

*  Tabula  Nervorum  Uteri,  Heidelberg,  1822,  folio. 


GENERAL   VIEW    OF    THE   SYMPATHETIC    SYSTEM.  8H 

The  tubal  nerves  are  also  derived  from  the  ovarian  plexuses. 

The  uterine  nerves  derived  from  the  hypogastric  plexuses  are  divided  into  ascending 
branches,  which  run  upward  along  the  lateral  borders  of  the  uterus,  pass  forward  and 
backward  upon  the  surfaces  of  that  organ,  and  terminate  in  its  substance  ;  and  into  de- 
scending branches,  which  run  along  the  sides  of  the  vagina,  and  terminate  in  it.  These 
vaginal  nerves  appear  to  be  inseparably  blended  with  the  vesical  and  hemorrhoidal 
nerves.* 

Such  are  the  divisions  of  the  hypogastric  plexuses  ;  analogy,  rather  than  direct  obser- 
vation, has  led  to  the  admission  of  the  existence  of  gluteal,  ischiatic,  and  internal  pudic 
plexuses ;  in  fact,  of  plexuses  around  all  the  branches  of  the  internal  iliac  arteries. 

The  Sacral  Poetion  of  the  Sympathetic  System. 

The  sacral  portion  of  the  sympathetic  (s  s,  fig.  302)  is  formed  on  each  side  by  a  cord  en- 
larged at  intervals,  and  situated  on  the  inner  side  of,  and  along  the  anterior  sacral  fo- 
ramina. 

It  forms  a  continuation  of  the  lumbar  portion  of  the  sjnnnpathetic ;  but  sometimes  there 
appears  to  be  an  interruption  in  the  ganglionic  chain,  between  the  fifth  lumbar  ganglion 
and  the  first  sacral.  This  interruption  is  merely  apparent ;  it  is  never  complete.  The 
sacral  trunks  of  the  sympathetic  of  the  right  and  left  sides  gradually  approach  each  other 
as  they  descend,  corresponding  in  this  respecf  to  the  anterior  sacral  foramina. 

The  sacral  ganglia,  which  are  rarely  five,  more  commonly  four,  and  sometimes  three 
in  number,  are  occasionedly  collected  into  a  small  gangliform  enlargement,  situated  be- 
tween the  first  and  second  anterior  sacral  foramen ;  the  first  sacral  ganglion  is  some 
times  double,  and  at  other  times  it  rather  resembles  a  gangliform  cord  than  a  true  gan- 
glion. 

The  mode  of  connexion  between  the  first  sacral  and  the  last  lumbar  ganglion  is  sub- 
ject to  much  variety.  +  The  manner  in  which  the  sacral  portion  of  the  sympathetic  terr- 
minates  is  also  somewhat  variable.  The  following  is  the  arrangement  most  generally 
admitted :  a  filament  proceeds  from  the  last  sacral  ganglion,  which  is  usually  the  fourth, 
and  forms  an  anastomotic  arch  with  its  fellow  of  the  opposite  side,  in  front  of  the  base 
of  the  cocc)rx.  At  their  point  of  junction  is  often  found  a  small  ganglion  (ganglion  inp- 
par,  c),  from  which  certain  terminal  filaments  are  given  off.  Sometimes  there  is  neither 
a  coccygeal  ganglion  nor  any  anastomosis,  properly  so  called,  but  the  terminal  filaments 
are  distributed  in  the  usual  way.  I  have  not  been  able  to  trace  these  filaments  beyond 
the  periosteum  of  the  coccyx  and  the  sacro- sciatic  ligaments. 

Like  the  other  ganglia  of  the  sympathetic,  the  sacral  ganglia  present  communicating 
branches  with  each  other ;  rather  large  external  branches  derived  from  the  corresponding 
sacral  nerves ;  internal  branches,  which  anastomose  with  those  of  the  opposite  side,  in 
front  of  the  sacrum,  and  surround  the  middle  sacral  artery.  Some  of  these  filaments  I 
have  distinctly  seen  entering  the  substance  of  the  sacrum ;  and^  lastly,  very  small  ante- 
rior branches  (y),  some  of  which  join  the  hypogastric  plexuses,  while  the  others  termi 
nate  directly  upon  the  rectum. 

General  View  of  the  Sympathetic  System. 

The  following  dissection  is  necessary,  in  order  to  present  a  correct  general  idea  of  the 
S)mapathetic  system. 

Take  a  spinal  column  which  has  been  macerated  in  diluted  nitric  acid,  remove  the 
bodies  of  the  vertebrae,  leaving,  if  it  be  wished,  the  inter- vertebral  substances ;  be  very 
careful  to  preserve  the  branches  of  communication  between  the  sympathetic  and  the  cra- 
nial and  spinal  nerves. 

It  is  then  clearly  seen  that  the  two  gangliated  trunks  of  the  S3rmpathetic  are  connect- 
ed with  the  cerebro-spinal  axis  by  as  many  roots,  or  small  groups  of  roots,t  as  there  are 
cranial  and  spinal  nerves ;  it  is,  moreover,  no  less  evident  that  the  communicating 
branches  between  the  ganglionic  chain  and  the  spinal  nerves  do  not  proceed  from  the 
ganglia,  but  from  the  spinal  nerves ;  so  that  it  may  be  stated  as  a  demonstrated  ana- 
tomical fact,  that  the  sympathetic  system  has  its  origin  in  the  cerebro-spinal  system  <) 

*  [Dr.  Lee  has  recently  examined  minutely  the  distribution  of  the  nerves  of  the  unimpregnated  and  fravid 
uterus.  He  has  described  (Anatomy  of  the  Nerves  of  the  Uterus,  with  plates,  1841,  and  Proceedings  of  the 
Royal  Society,  No.  49)  several  large  uterine  plexuses  ;  also,  several  "  large  ganglia  on  the  uterine  nerves,  and 
on  those  of  the  vagina  and  bladder ;"  and,  farther,  ''  two  great  ganglia  situated  on  the  sides  of  the  neck  of  the 
uterus."]  1  •  •     J   u 

t  In  one  case,  the  continuation  of  the  lumbar  portion  of  the  sympathetic  deviated  outward,  and  joined  the 
fifth  lumbar  nerve  ;  a  very  small  filament  only  formed  the  communication  between  the  last  lumbar  ganglion 
and  the  first  sacral.  In  another  case,  these  two  filaments  proceeded  from  the  last  lumbar  ganglion  of  the  right 
side,  t'ae  inner  of  which  joined  the  first  sacral  ganglion  of  the  opposite  side,  crossing  over  the  sacro-vertebral 

t  It  must  be  remembered  that  there  are  always  two,  and  sometimes  three  communicating  branches  between 
the  sympathetic  and  each  of  the  spinal  nerves. 

4  These  facts  in  human  anatomy  are  in  perfect  accordance  with  the  observations  in  comparative  aiiatomr 
made  by  Meckel  and  Weber,  namely,  that  the  development  of  the  sympathetic  system  is  in  direct  ratio  with 
that  of  the  cerebro-spinal  system  ;  tliat  the  former  is  more  developed  in  man  than  in  any  other  animal,  and  19 
proportionally  larger  in  the  fietus  than  in  the  adult. 


872  NEUROLOGY. 

The  sympathetic  trunks  of  the  right  and  left  side  generally  anastomose  below  in  front 
of  the  coccyx ;  it  has  been  somewhat  hastily  affirmed  that  they  anastomose  above,  either 
upon  the  pituitary  body,  or  upon  the  anterior  communicating  artery  of  the  brain ;  the 
true  anastomoses  of  the  two  halves  of  the  sympathetic  system  are  in  the  central  and 
median  plexuses. 

If,  after  having  acquired  this  general  idea  of  the  trunks  of  the  sympathetic,  its  neuri- 
lemma be  removed  by  continued  maceration  in  water,  the  connexions  of  the  branches 
given  from  the  spinal  nerves  to  the  ganglia,  with  the  branches  given  from  the  ganglia  to 
the  viscera,  may  then  be  ascertained  :  it  then  becomes  evident,  that  the  greater  number 
of  the  branches  from  the  spinal  nerves  do  not  penetrate  to  the  centre  of  the  ganglia,  but 
expand,  as  it  were,  upon  their  surface,  and  divide  into  two  sets  of  filaments ;  of  these, 
some  are  applied  to  the  surface  of  a  ganglion,  and  proceed  directly  to  form  the  internal 
or  visceral  branches  ;*  while  the  others  assist  in  forming  the  cords  of  communication 
between  one  ganglion  and  another,  and  divide  into  ascending  and  descending  filaments, 
of  which  the  latter  are  the  more  numerous.  They  all  run  along  the  outer  side  of  the  cords 
of  communication,  and  afterward  become  visceral  branches  themselves  ;  it  is  doubtful 
whether  any  filament  arises  in  the  interior  of  a  ganglion  ;  the  continuity  of  them  all  can 
be  traced  completely  through  these  bodies. 

It  follows,  therefore,  that  it  is  anatomically  shown  that  the  visceral  nerves  given  off 
from  the  sympathetic  are  connected  or  belong  to  a  very  great  nimiber  of  spinal  nerves 
at  once,  and  always  to  spinal  nerves  much  higher  than  that  portion  of  the  sympathetic 
from  which  the  visceral  branches  are  immediately  given  off;  and  again,  that  the  vis- 
ceral or  splanchnic  nerves,  the  actual  origins  of  which  we  have  seen  to  be  so  complica- 
ted and  so  remote  from  their  apparent  origins,  always  run  a  very  long  course  before 
reaching  their  destination.  Thus,  the  splanchnic  nerves  of  the  thorax  or  the  cardiac 
nerves  are  derived  from  the  cervical  ganglia ;  the  splanchnic  nerves  of  the  abdomen  are 
given  off,  for  the  most  part,  by  the  thoracic  ganglia  ;  and  most  of  the  splanchnic  nerves 
of  the  pelvis  proceed  from  the  lumbar  ganglia.  Nevertheless,  the  proper  ganglia  of  each 
splanchnic  cavity  complete  the  visceral  nerves  belonging  to  that  cavity.  Thus,  the  first 
thoracic  ganglion  assists  in  the  formation  of  the  cardiac  nerves ;  the  superior  lumbar 
ganglia  in  that  of  the  visceral  nerves  of  the  abdomen  ;  and  the  sacral  ganglia  in  that  of 
the  pelvic  nerves. 

The  visceral  nerves  sometimes  pass  directly  to  the  viscera  from  the  ganglia  of  the 
sympathetic,  and  sometimes  indirectly,  after  being  mingled  and  combined  in  plexuses. 

There  is  no  relation  between  the  branches  which  enter  and  those  which  pass  out  of 
the  several  visceral  plexuses,  so  that  the  branches  which  proceed  from  the  ganglia  and 
trunk  of  the  sympathetic  to  those  plexuses  must  be  regarded,  not  as  branches  of  forma- 
tion, but  as  branches  of  communication. 

The  visceral  plexuses  are  also  formed  in  a  very  peculiar  manner,  not  only  by  inter- 
laced nerves,  but  by  nerves  and  ganglia,  and  these  nerves  themselves  present  a  gangli- 
onic structure  altogether  different  from  the  fasciculated  and  plexiform  structure  of  other 
nerves. 

There  are  four  great  visceral  plexuses  :  the  pharyngeal  plexus,  the  cardiac  plexus,  the 
solar  plexus,  and  the  hypogastric  plexus  ;  the  largest  of  all  these  is  the  solar  plexus, 
which,  both  in  an  anatomical  and  in  a  physiological  point  of  view,  deserves  the  title  of 
the  abdominal  brain,  which  was  given  to  it  by  Wrisberg.  These  four  great  plexuses 
may  also  be  very  properly  regarded  as  nervous  centres,  to  which  all  the  physiological 
and  pathological  phenomena  of  the  nutritive  system  are  singly  or  collectively  referred. 

These  visceral  plexuses  differ  as  much  from  the  ganglionic  chain  formed  by  the  two 
trunks  of  the  sympathetic  as  these  trunks  differ  from  the  spinal  cord  itself :  in  these 
plexuses  a  sort  of  fusion  is  effected  between  the  cerebro-spinal  and  the  sympathetic  sys- 
tems, and  also  between  the  trunks  of  the  sympathetic  belonging  to  the  two  sides  of  the 
body. 

The  pneumogastrie  assists  in  the  formation  of  three  of  these  jdexuses  ;  namely,  the 
pharyngeal,  the  cardiac,  and  the  solar  plexus.  In  man  there  is  a  tendency  to  fusion  of 
the  pneumogastrie  with  the  sympathetic,  and  in  the  lower  animals  this  fusion  is  still 
more  complete  ;  it  is  in  those  animals  in  which  the  sympathetic  is  the  least  developed 
that  the  par  vagum  acquires  its  greatest  development,  and  supplies  the  place  of  the  for- 
mer in  reference  to  the  intestinal  canal. 

The  glosso-pharyngeal  nerve  also  assists  in  the  formation  of  the  pharyngeal  plexus, 
and  the  sacral  nerves  contribute  to  that  of  the  hypogastric  plexus. 

The  visceral  plexuses  differ  essentially  from  those  formed  by  the  cerebro-spinal  nerves. 
In  the  latter,  the  branches  which  emerge  from  the  plexus  are  precisely  the  same  branch- 
es that  entered  it,  only  combined  in  a  different  manner.  However  inextricable  they 
may  be,  the  plexuses  of  the  spinal  nerves  are  merely  points  in  which  a  number  of  affe- 
rent branches  converge  and  combine  together.  In  the  visceral  plexuses,  on  the  contra- 
ry, there  is  no  relation,  either  in  size  or  structure,  between  the  afferent  branches  and 
the  plexuses  themselves. 

*  Some  filaments  from  the  spinal  nerves  are  seen  to  croFS  at  right  angles  over  the  anterior  surface  of  the 
gang^iia,  and  then  to  join  the  visceral  nerves  ilirectlv. 


GENERAL    VIEW    OF    THE    SYMPATHETIC    SYSTEM. 


873 


The  nerves  derived  from  the  sympathetic  system  differ  eilso  in  their  mode  of  distribu- 
tion from  the  nerves  of  the  cerebro-spinal  system.  In  general,  they  form  a  plexiform 
sheath  around  the  vessels,  and  enter  with  them  into  the  substance  of  organs.  This  ar- 
rangement has  induced  some  anatomists  to  believe  that  the  sjrmpathetic  nerves  belong 
essentially  and  exclusively  to  the  vascular  system,  and  are  lost  upon  the  coats  of  the 
arteries ;  others  hold  an  opposite  opinion,  and  deny  altogether  that  the  sympathetic 
nerves  enter  the  coats  of  those  vessels.  From  some  researches  which  I  have  made  on 
this  subject,  I  believe  that  there  are  proper  filaments  for  the  coats  of  the  vessels,  but 
that  these  are  very  few  in  number,  and  that  by  far  the  larger  number  of  the  nervous  fila- 
ments are  intended  for  the  several  organs.  It  is  not  uninteresting  to  remark,  that  the 
s)Tnpathetic  nerves  always  accompany  the  arteries,  and  never  the  veins ;  the  trunk  of 
the  vena  portae  forming  the  only  exception  to  this  rule. 

A  gray  colour  and  a  soft  texture  are  not,  as  is  generally  stated,  the  peculiar  character- 
istics of  the  nerves  of  the  sympathetic  system ;  the  gray  colour  is  observed  only  in  a 
portion  of  this  system  ;  and  the  softness,  which  only  very  rarely  accompanies  the  gray 
colour,  is  confined  to  a  very  minute  portion  of  it  indeed. 

There  are  gray  cords,  which  are  nothing  more  than  prolonged  ganglia,  and  are  not 
nerves,  properly  so  called  ;  when  examined  they  present  no  nervous  structure,  that  is 
to  say,  they  contain  no  white  funiculi  which  can  be  decomposed  into  primitive  filaments 
as  fine  as  the  silk  fibre.  Almost  all  the  sympathetic  nerves  are  of  a  white  colour,  which 
is  sometimes  conceeiled  by  an  unusually  thick  neurilemma.  The  structure  of  the  white 
nerves  of  the  sympathetic  system  does  not  differ  from  that  of  the  cerebro-spinal  nerves  ; 
except  that  the  funicidi  of  the  former  are  smaller,  and  their  arrangement  is  more  deci- 
dedly plexiform.*  Lastly,  there  are  some  mixed  nerves,  partly  gray  and  partly  white, 
which  partake  of  the  structural  characters  of  both  the  gray  and  the  white  nerves,  t 

*  See  note,  p.  840. 

+  I  am  much  indebted  to  M.  C.Bonamy,  my  private  prosector,  for  the  zeal  and  ability  with  which  he  ha» 
assisted  me  in  the  numerous  dissections  required  for  the  compilation  of  this  work. 


SOURCES  FROM  WHICH  THE  ILLUSTRATIVE  ENGRAVINGS  HAVE  BEEN  TAKEN. 


Figs.  1  to  7,  8t,  9  to  20,  24,  25,  28  to  30,  33,  34,  36, 
38,  41  to  45,  47,  48t,  49  to  53,  57  (Sue). 

Figs.  21  to  23,  37  (Gordon). 

Figs.  26,  27,  35,  58t  to  60t,  61  to  70,  71t,  72  to  84, 
106  to  110,  lilt,  112,  113, 114t,  115,  116t  to  123t,  124 
to  126,  127t,  128  to  133,  141t,  147t,  155,  161,  163t, 
169t,  170,  171t,  191t,  192,  194,  195  (Bourgery). 

Figs.  39,  40,  46t,  54  to  56  (Ckeselden). 

Figs.  85  to  94  (Hunter). 

Fig.  95  (d.)  (Retzius). 

Fig.  97  (d.)  (Goodsir). 

Fig.  98  (Serres). 

Figs.  99,  101,  102  (Blake). 

Fig.  lOO  (T.  Bell). 

Figs.  103  (d.)  to  105  (d.),  286  (Cloquet). 

Figs.  136t,  138,  181  (Morion). 

Fig.  UOf  (Watts). 

Figs.  142,  173  to  175,  178, 231,  233,  234,  257  (Sam- 
mrring). 

Figs.  145,  160, 182, 187, 189,220,221,223t(We6er). 

Figs.  152,  153  (Boyd). 

Figs.  154t,  198  to  206,  208  to  218  (Tiedemann). 

Fig.  156  (No.  2)  (Krause). 

Fig.  156  (No.  3)  (Dallinger). 

Figs.  157  to  159,  162  (Boehm). 


Fig.  172  (Reisseissen). 

Fig.  180  (d.)  (Wagner). 

Fig.  183  (A.  Cooper). 

Fig.  185  (Holier). 

Figs.  207,  232t,  235  to  240,  242  to  246,  248,  249, 
251t,  252  to  256,  258  to  265,  266,  269  to  275,  284,  285, 
296tto301t  (Arnold). 

Fig.  219t  (Walter). 

Fig.  222t  (Caldani). 

Fig.  226  (Harvey). 

Figs.  227,  228  (Gurlt) 

Fig.  250  (Brewster). 

Fig.  268  (Cruveilhier). 

Figs.  281t,  283,  295  (Mayo). 

Figs.  289t,  290t  (Saan). 

Fig.  302t  (Manec). 

Figs.  143  (d.),  144  (d.),  164*  (d.),  179  (d.),  193+, 
197,  241  (d.),  276  to  280,  282  (Models,  Castt,  and  Di 
agrams  in  the  Museum  of  Anatomy,  University  College). 

Figs.  31,  32,  96, 98*  (d.),  134  (d.),  135  (d.),  137  (d.), 
139  (d.),  146  (d.),  148  (d.),  149  (d.)  to  151  (d.),  156 
(No.  1,  d.),  164,  176  (d.)  to  178  (d.),  184  (d.),  186  (d.), 
190  (d.),196  (d.),218*  (d.),224  (d.),225  (d.),229  (d.), 
230  (d.),  247  (d.),  267  (d.),  287  (d.),  288  (d.),  291  (d.) 
to  293  (d.)  (Original). 


Figs.  165  to  168  (Kieman). 

The  mark  (t),  affixed  to  the  number  of  a  figure,  indicates  that  such  figure  differs  in  some  respects  from  the 
(aiginal.  The  letter  (d.),  similarly  aflixed,  signifies  that  the  figure  is  intended  as  a  diagram  or  plan.  Th« 
asterisk  (*),  used  occasionally,  serves  to  distinguish  between  two  figures  bearing  the  same  number 

5S 


««#***'<' 


'*ll^- 


INDEX. 


Abdomen,  aponeurosis  of,  anterior,  300. 

posterior,  305. 

superficial,  297. 

regions  of,  352. 

Abducens,  nerve.     See  Nerve,  Motor  Ocul. 
Abductor  muscles.     See  Muscles. 
Accessory  ligaments.     See  Ligaments. 

nerves.     See  Nerves. 

Acetabulum,  88. 

Acini  of  glands.     See  those  glands. 

Acromion  process,  76. 

Adductor  muscles.     See  Muscles. 

Adipose  tissue,  175. 

Alee  of  sphenoid  bone,  lesser,  37. 

greater,  37. 

vespertilionis,  475. 

Alimentary  canal,  322. 

appendages  of,  384. 

coats  of,  322. 

direction  and  situation  of,  323. 

divisions  of,  322. 

——————  dimensions  of,  323. 

form  of,  323. 

•  membranes  of,  323. 

'  muscular  fibres  of,  323. 

structure  of,  323. 

Alveoli,  53,  58. 
Amphiarthroses,  113. 

■  characters,  ligaments,  and  motions,  113 

Ampulla  of  semicircular  canals,  677. 

Amygdala,  333.     See  Tonsils. 
Amygdaloid  fossa,  331. 
Anastomoses  of  arteries,  496. 

lymphatics,  614. 

nerves,  762. 

veins,  574. 

Anastomotic  artery,  brachial,  544. 

femoral,  565. 

ATUitomy,  objects  and  divisions  of,  1,  2. 
descriptive,  1. 

general,  1,  2. 

Anfractuosities.    See  Cerebrum. 

Angeiology,  479, 

Angle,  sacro-vertebral,  26. 

of  the  femur,  93. 

facial,  of  Camper,  45. 

occipital,  of  Daubenton,  45. 

of  the  jaw,  58. 

changes  daring  growth,  59. 

of  the  pubes,  89. 

Angles  of  bones,  9. 
AtucIc  joint,  168. 

ligaments  of,  169. 

Ankle.     See  Tarsus. 

Annular  ligaments.     See  Ligament!. 

Anti-helix,  and  its  fossa,  666. 

tragus,  666. 

Antrum  Highmori,  52. 

pylori,  355. 

Anus,  380. 

muscles  of,  380. 

structure  of,  380 

Aorta.     See  Arteries. 
Aponeurology,  294. 
Aponeuroses  in  general,  294. 
classification  of,  294. 

containing,  294. 

definition  of,  294. 

functions  of,  296. 

insertion  of,  294. 

structure  of,  296. 

■  tensor  muscles  of,  295. 
Aponeuroses  in  particular,  297. 
—————  abdominal  anterior,  300. 

layers  of,  301. 


Aponeuroses,  cervical,  superficial,  299. 

cephalo-pharyngeal,  346. 

costo-clavicular,  137. 

of  the  cranium,  299. 

cremasteric,  302. 

cribriform,  309. 

deltoid,  315. 

dorsal  of  the  foot,  314. 

metacarpus,  318 


interosseous,  of  foot,  314. 
hand,  318. 


■  epicranial,  298. 

■  external  oblique,  301 

■  of  the  eyehds,  647. 
face,  299. 

■  femoral,  309. 

septa  of,  310. 

sheath  for  vessels,  310. 

'  muscles,  311. 


posterior,  305. 
superficial,  297. 


brachial,  316. 
buccinator,  298. 
buccinato-pharyngeal,  235. 
cervical,  deep,  299. 


-  of  the  fore-arm,  316. 
-gluteal,  311. 

-  hypothenar,  319. 

•  iliac,  306. 

•  infra-spinous,  315. 

•  intercostal,  360. 

■  inter-muscular  of  thigh,  310. 

•  of  internal  oblique,  304. 
■of  the  leg,  312. 

lower  extremity,  309. 

superficial,  297. 


■  lumbar,  or  posterior  abdominal,  30i6. 

•  lumbo-iliac,  306. 

-  masseteric,  298. 

-  of  the  neck,  299. 

-  obturator,  309. 

-  occipito-frontal,  298. 

-  occipito-pharyngeal,  346. 
-palmar,  319. 
-parotid,  298. 

■  pedal,  314. 

■  pelvic  lateral,  308. 
superior,  308. 

■  of  the  pelvis,  306. 
proper,  307. 

•  perineal,  deep,  307. 
superficial,  306. 


■  petro-pharyngeal,  346. 

■  of  the  pharynx,  346. 

'  plantar,  external,  314. 

internal,  314. 

■  interosseous,  315. 
middle,  314. 


—  prasvertebral,  299. 

—  of  the  quadratus  lumborum,  306. 

—  recto-vesical,  308. 

—  of  the  serratus  posticus,  300. 
shoulder,  315. 

•  spermatic  cord,  304. 


sub-peritoneal,  305. 

sub-scapular,  315. 

superficial,  2i97. 

of  abdomen,  297. 

supra-clavicular,  299. 

supra-spinous,  315. 

temporal,  298. 

thenar,  319. 

of  the  thorax,  300. 

of  transversalis,  305. 

of  the  upper  extremity,  316. 

superficial,  297. 


■  of  velum  palati,  346. 
-  vertebral,  205. 

■  vesical,  309. 


Aponeurotic  sheaths  for  muscles,  296. 
tendons,  296. 
vessels,  296. 


Apparatus,  hyoid,  109. 
Apparatttses  of  human  body,  general  view  of,  3,  4. 
Appendices  epiploicse,  372. 
Appendix,  ensiform,  or  xiphoid,  65. 
vermiformis,  373 


876 


INDEX. 


Appendix,  vermiformis,  development  of,  384. 

structure  of,  373. 

Aqueductus  Fallopii,  43,  839. 

vestibuli,  44. 

cochlea;,  44. 

Sylvii,  719,  742 

Aqueous  humour,  65.5. 

membrane  of,  655. 

Arachnoid,  687. 

canal  (of  Bichat),  687. 

cranial  portion  of,  ©7. 

internal,  691. 

loose,  690. 

membrane  of  eye,  656  (note). 

spinal  portion  of,  690. 

uses  of,  692. 

Arbor  vitas  uterina,  465. 
Arch,  aortic,  502. 

of  colon,  374. 

crural,  302. 

femoral,  302. 

gluteal,  3U. 

orbital,  36. 

palatine,  329. 

pubic,  89. 

sub-pubic,  307. 

■ zygomatic,  61. 

Arches,  alveolar,  174. 

dental,  174. 

zygomatic,  61. 

Arm,  bone  of,  78. 

compared  -with  thi^h  bone,  107. 

Arteries  in  general,  496. 

anastomoses  of,  496. 

branches  of,  497. 

coat  of,  external  or  cellular,  498. 

internal,  498. 

. middle,  proper,  or  elastic,  498. 

— ..— - —  course  or  direction  of,  496. 

definition  of,  496 

division  of,  496. 

form  of,  496. 

nerves  of,  497. 

nomenclature  of,  495. 

origin  of,  496. 

preparation  of,  497. 

relations  with  other  parts,  497. 

retia  mirabilia  of,  496. 

satellite  muscles  of,  497. 

sheaths  for,  499. 

structure  of,  499. 

termination  of,  498. 

varieties  of,  496. 

vasa  vasorum  of,  499. 

venae  comites  of,  497. 

vessels  of,  499. 

Artery  or  Arteries  in  particular,  497. 

of  particular  organs  or  tissues. 

gans,  Sec. 
acromial,  descending,  542. 

supra-scapular,  538. 

transverse,  542. 

acromio-thoracic,  542. 

of  ala  nasi,  518. 

alar  thoracic,  542. 

alveolar,  524. 

anastomotic,  brachial,  544. 

-  great,  of  thigh,  564. 


See  those  or- 


angular,  of  face,  517,  529 
aorta,  501. 

abdominal,  503. 

arch  of,  502. 

ascending,  503. 

branches  of,  503 

descending,  503. 

sinuses  of,  501. 

thoracic,  503. 

valves  of,  486. 

arising  from  abdominal  aorta,  606. 

'■ —  arch  of  aorta,  513. 

varieties  of,  513. 


origin  of  aorta,  504. 
termination  of  aorta,  552. 
thoracic  aorta,  505. 


articular,  of  hip,  564. 

knee,  inferior,  565. 

middle,  or  azyg»s,  565. 

superior,  565. 


-  ascending  cervical,  538 
pharyngeal,  520. 


Arteri;  auricalar,  anterior,  521. 
posterior,  519. 


aiiliary,  531,  542. 
axis,  coeliac,  507. 

thyroid,  535. 

azygos,  or  middle  articular  of  knee  565. 
basilar,  534. 
brachial,  543. 
brachio-cephalic,  531. 
bronchial,  505. 

'  distribution  of,  421. 


buccal,  524. 
of  bulb,  558. 
calcaneal,  external,  570. 
inferior,  571 


capsular,  inferior,  513. 

middle,  513. 

superior,  513. 


cardiac,  503. 

carotid,  common,  left  and  right,  514. 

general  distribution  of,  530. 


■  external  or  facial,  515. 
-  internal,  525. 
•  superficial,  515. 


carpal,  radial,  anterior,  546. 

posterior  dorsal,  546. 

ulnar,  anterior,  549. 

posterior  dorsal,  549. 


central  of  retina,  597,  665. 
cerebellar,  inferior,  anterior,  534. 
posterior,  534. 


■  superior,  635. 


cerebral,  anterior.  529. 

■  communicating  anterior,  529. 

•  posterior,  529. 


middle,  530. 

posterior,  537. 

cervical,  ascending,  538. 

deep,  540. 

princeps,  519, 

superficial,  539. 


cervico-spinal,  538. 
choroid,  anterior,  530. 
posterior,  536. 


ciliary,  anterior,  527. 

middle,  or  long,  528. 

posterior,  or  short,  528,  665. 


circle  of  Willis,  536 
circumflex,  femoral,  external,  564. 
internal,  563. 


iliac,  560. 
humeral,  anterior,  543. 
posterior,  543. 


of  clitoris,  558. 
coccygeal,  552. 
coeliac  (axis),  507. 
colic,  left,  511. 

right,  510. 

collateral,  of  fingers,  radial,  547. 
ulnar,  549. 


humeral,  external,  543. 

internal,  543. 

of  knee.     See  Articular. 

of  toes,  from  external  plantar,  57 

internal  plantar,  572 

comites.     See  Satellite. 
communicating,  cerebral,  anterior,  529. 

posterior,  529,  535 


palmar,  548. 
plantar,  572. 
of  Willis,  529. 


coronary  of  heart,  left  or  anterior,  504. 

right  or  posterior,  504. 


•  lips,  inferior,  5l7. 
superior,  518. 

•  stomach,  507. 


of  corpus  callosum,  529. 

cavemosum,  558. 


cremasteric,  560. 

crural,  560. 

cystic,  508. 

deep,  brachial  or  humeral,  544. 

cervical,  540. 

femoral,  563. 

temporal,  522. 

deferential,  452. 

dental,  anterior,  524. 

inferior,  523. 

superior,  524. 

■  diaphragmatic,  inferior,  506. 


INDEX. 


877 


Artery,  diaphragmatic,  superior,  539. 

digital,  collateral,  radial,  547 

ulnar,  549. 


of  foot,  572. 


dorsal,  carpal,  radial,  547. 
ulnar,  549. 


■  of  foot,  568. 
—  index  finger,  548. 
metacarpal,  radial,  547. 
ulnar,  549. 


•  metatarsal,  569. 

•  of  nose,  529. 

—  penis,  558. 

—  scapula,  538. 

—  tarsus,  572. 

—  thumb,  548. 

—  toe,  great,  572. 
tongue,  518. 


-  dorsi-spinal,  of  inferior  intercostals,  507. 

superior  intercostals,  540 

-  emulgent,  512. 

■  epigastric,  559. 
Superficial,  562. 

■  epiploic,  510. 

■  ethmoidal,  anterior,  528. 
posterior,  528.  • 

■  facial,  517. 

•  femoral,  559. 

deep,  563. 


Artery,  magna  pollicis,  of  hand,  547. 

malar  cutaneous,  521. 

malleolar,  externa],  567. 

internal,  567. 


mammary,  external,  542. 

internal,  539. 

■  masseteric,  521,  523. 
'  mastoid,  520. 
posterior,  519. 

maxillary,  external,  517. 

internal,  522. 

general  distribution  of,  525. 

of  median  nerve,  549. 


mediastinal,  540. 

medullary,  506. 

meningeal,  anterior,  528. 

middle  or  great,  522. 

of  ascending  pharyngeal,  620. 

posterior,  519,  514. 

small,  523. 


-  of  fissure  of  Sylvius,  529. 
-of  fraenum  lingua;,  519. 

-  frontal,  529. 

of  temporal,  520. 

•  gastric,  inferior,  509. 

superior,  509. 

■  gastro-duodenal,  508. 

epiploic,  left,  509. 

right,  508. 


hepatic,  508. 

•  gluteal,  inferior,  556. 
superior,  556. 


•  hemorrhoidal,  557. 

inferior,  557. 

middle,  554. 

-superior,  511. 


-  helicine,  456. 

■  hepatic,  508. 

—  in  the  liver,  391,  392. 

■  humeral,  543. 

deep,  inferior,  544. 

deep,  superior,  544. 

■hyoid,  of  lingual,  518. 

superior  thyroid,  515  (note). 

•  hjrpogastric,  553. 

•  iliac,  common,  552. 

external,  559. 

internal,  553. 

general  distribution  of,  558. 


—  mental,  523. 
--  mesenteric,  inferior,  511. 
•  superior,  510. 


metacarpal,  radial,  546. 
■  ulnar,  549. 


•  metatarsal,  569. 
■  muscular,  of  orbit,  528. 
thigh,  562. 

•  musculo-phrenic,  540. 
for  mylo-hyoideus,  523. 
nasal,  528. 

•  dorsal,  529. 


--  lateral,  518. 
—  of  pterygo-palatine,  524. 
of  septum,  518. 


nutritious,  of  femur,  542. 

fibula,  570. 
humerus,  545. 
tibia,  569. 


■  obturator,  554. 

•  occipital,  519. 

•  (Esophageal,  505. 

•  omphalo-mesenteric,  511. 
ophthalmic,  525. 

'  orbital,  of  temporal,  521. 
ovarian,  512. 
palatine,  inferior,  517. 
—  superior,  524. 


■  ileo-colic,  511. 

■  ilio-lumbar,  555. 

■  incisory,  inferior,  523. 
superior,  524. 

•  infra-orbital,  524. 

or  sub-scapular,  542. 

spinous,  542. 

'  innominate,  531. 

■  intercostals,  anterior,  540. 

aortic  or  inferior,  505. 

superior,  540. 

•  interlobular,  of  liver,  391. 

•  interosseous,  dorsal,  of  foot,  569. 
—  hand,  547. 


of  forearm,  anterior,  548. 

posterior,  549. 

palmar,  547 

■ plantar,  572. 

recurrent,  of  forearm,  549. 

■  of  the  intestines,  great,  511. 
■  small,  510. 


intra-spinal,  534. 

ischiatic,  556. 

of  labia  pudendi,  558. 

labial,  inferior,  517. 

superior,  517. 

lachrymal,  526. 

laryngeal,  inferior,  516. 

superior,  516. 

lingual,  518. 

lumbar,  506. 

magna  pollicis,  of  foot,  572. 


■  palmar,  deep,  546. 

'  palmar,  interosseous,  548. 

superficial,  547. 

■  recurrent,  547. 


•  palpebral,  inferior,  528. 
superior,  528. 

•  pancreatic,  great  (from  splenic),  509. 
small  (from  mesenteric),  510, 

•  pancreatico-duodenal,  508. 

■  parietal,  519,  521. 

■  parotid,  520. 

•  of  penis,  558. 
dorsal,  558. 

'  perforating,  of  forearm,  549 

palmar,  548. 

peroneal,  570. 

plantar,  anterior  and  posterior,  569. 

572. 
•  of  thigh,  564. 


•  pericardiac,  495. 

perinaeal,  superficial,  557. 
transverse,  557. 

peroneal,  570. 

anterior,  570. 

•  perforating,  570. 


■  pharyngeal,  ascending  or  inferior,  520. 

■  pharyngo-meningeal,  520. 
•  phrenic,  inferior,  507. 

■  superior,  539. 


■  for  phrenic  nerve,  539. 

■  plantar,  external,  571. 
'  internal,  571. 


■  popliteal,  564 

•  prevertebral,  520. 

•  princeps  cervicis,  519. 
—  pollicis,  547. 


profunda  cervicis,  549. 

femoris,  563. 

humeri,  inferior,  545. 

superior,  544. 


pterygoid,  of  facial,  517. 
internal  maxillary,  523. 


INDEX. 


Artery,  pterygo- palatine,  524.  "^tffl^ 

pudic,  external  inferior;  562.'' 

superior,  56?. 


internal,  557. 

—  in  the  female,  558. 


pulmonary,  500. 

'~  left  branch  of,  501. 

right  branch  of,  501. 

'  distribution  of,  431. 


pyloric,  inferior,  508. 

superior,  508. 

radial,  546. 

■  collateral  of  fingers,  547. 


recurrent,  540. 

radialis  indicis,  548. 

radio-cubital,  549. 

palmar,  547. 

ranine,  518. 

of  receptaculum,  525. 

— recurrent  interosseous,  of  forearm,  549. 

palmar,  547. 

radial,  546. 

tibial,  anterior,  668. 

internal,  569. 


'  ulnar,  anterior,  549. 
'  posterior,  549. 


■  renal,  512. 
distribution  of,  439. 

■  of  retina,  central,  527. 

■  sacral,  lateral  inferior,  556. 
superior,  556. 


middle  or  anterior,  552. 

satellite  of  median  nerve,  549. 

phrenic,  540. 

sciatic,  556. 

ulnar,  548. 

• scapular,  inferior,  542. 

posterior,  538. 

■  superior,  538. 


—  sciatic,  556. 

—  for  sciatic  nerve,  556. 
scrotal,  557. 

—  of  septum  of  nose,  518. 
' ventricles  of  heart,  504. 

—  short,  of  stomach,  511. 

—  sigmoid,  511. 
spermatic,  511. 

—  spheno-palatine,  524. 
spinous,  522. 

—  spinal,  534,  609. 
anterior,  534. 

■  general  distribution  of,  609. 


Artery,  thoracic  htuneral,  or  deltoid,  of  acromio-tbora 
cic,  542. 

inferior,  542. 

long,  542. 


-  thymic,  540. 

-  thyroid  axis,  537. 

inferior,  537. 

middle,  515. 

of  Neubauer,  537. 

superior,  516. 

•  tibial,  anterior,  567. 

posterior,  570. 

recurrent,  567. 

•  tibio-peroneal,  569. 
'  tonsillar,  521. 

■  transverse,  of  perineum,  556. 

neck,  539. 

face,  521. 

•  shoulder,  538. 


■  tympanic,  522. 

•  ulnar,  548. 

collateral,  543. 

of  fingers,  649. 

recurrent,  anterior,  549. 

posterior,  549. 

'  umbilical,  553. 

•  uterine,  554. 

■  vaginal,  554. 

• of  liver,  392. 

■  vasa  brevia,  of  stomach,  609. 

•  for  vertebrae,  504. 

•  vertebral,  533. 

•  vesical,  553. 

■  vidian,  524. 


Arthrodia,  114. 

characters,  ligaments,  and  motions,  115 
Arthrology,  111. 
Articular  surfaces,  in  general,  111. 

-  of  particular   articulations, 
those  articulations. 


Se« 


posterior,  534. 

re-enforcing,  cervical,  534. 

lumbar,  504. 

thoracic,  504. 

of  spinal  cord,  504,  634. 

— ^ —  splenic,  509. 

in  spleen,  405. 

for  sterno-mastoid,  516,  519. 

stylo-mastoid,  519. 

sub-clavian,  left  and  right,  531. 

sub-diaphragmatic,  504. 

sub-lingual,  518. 

■  for  sub- maxillary  gland,  517. 


—— —  sub-mental,  517. 
— — —  sub-scapular,  542. 

superciliary,  527. 

superficial,  of  neck,  546. 

palm,  547. 

perineum,  556. 

superficialis  voIk,  547. 

supra-orbital,  527. 

renal,  inferior,  512. 

middle,  512. 

■  superior,  512. 


.  sural,  565. 


scapular,  538. 
'  spinous,  538. 


tarsal,  dorsal,  or  external,  568. 

internal,  568. 

temporal,  521. 

■ deep  anterior,  524 

middle,  521. 

•  posterior,  523. 


superficial,  521. 


testicular,  511. 

■  distribution  of,  536. 


thoracic  acromial,  542. 
alar,  542  (note). 


•  borders,  112, 

structure  of,  177. 

■  cartilages.  111. 
structure  of,  177. 

■  cavities,  10. 

supplementary,  128. 

processes,  or  eminences,  10. 

of  Tertebrse,  20,  22. 

—  union  of,  116. 


Articular  arteries.     See  Arteries. 

nerves.     See  Nerves. 

Articulations  in  general,  111-116. 

■  amphiarthroses,  113. 

arthrodia,  1 14. 

classification  of,  113. 


condylarthrosis,  114. 

definition  of.  111. 

diarthroses,  113. 

enarthrosis,  114. 

ginglymus,  114. 

gomphosis,  114. 

harmonia,  114. 

— ■  immovable,  113. 
— -  meningoses,  113 

mixed,  113. 

movable,  113. 

movements  of,  113. 

—  by  mutual  reception,  113. 
schindylesis,  114. 

—  sutures,  114. 

—  symphyses,  114. 

—  synarthroses,  114. 

—  synchondroses,  113. 

—  syneuroses,  113. 

—  syssarcoses,  113. 

—  trochlear,  114. 
•  trochoid,  114. 


Articulations  in  particular,  113. 

acromio-clavicular,  135. 

mechanism  of,  136. 


'  of  ankle.     See  Tibio-tarsal, 
■  astragalo-scaphoid,  171. 
'  of  astragalus  with  os  calcis,  170. 
■  movements  of,  153. 


atlanto-axoid,  117. 

'  mechanism  of,  124. 


'odontoid,  117. 


'  of  atlas  and  axis,  117. 

articular  processes  of, 

118 


INDEX. 


879 


Arttculations,  calcaneo-cuboid,  173. 

carpal,  in  general,  147. 

.  —  mechanism  of,  148. 

of  each  row,  147. 

of  two  rows  together,  147. 

■  pisiform  and  cuneiform,  147. 


■  carpo- metacarpal,  in  general,  149 

mechanism  of,  150. 

first,  149. 

mechanism  of,  150. 

fifth,  150. 

mechanism  of,  150. 

second,  third,  &  fourth, 

150. 
•  carpo-metacarpal,  of  the  thumb,  150. 
■  mechanism  of,  150. 


■  chondro-costal,  132. 

•  sternal,  in  general,  131. 

in  particular,  131. 

movements  of,  133. 


■  coccygeal,  120. 

■  condyloid,  of  occiput  and  atlas,  116. 
•  coraco-clavicular,  135. 

•  mechanism  of,  136. 


'  of  the  costal  cartilages,  132. 

•  movements  of,  132. 


■  costo-clavicular,  138. 
mechanism  of,  138. 

■  costo-transverse,  131. 
vertebral,  131, 

in  general,  131. 


in  particular,  131. 

movements  of,  131. 

proper,  131. 

of  first  rib,  131. 

of  eleventh  and  twelfth 

ribs,  131. 

•  coxo-femoral,  159. 
movements  of,  161. 

•  cranial,  124. 
■  mechanism  of,  125. 


—  cranio-vertebral,  120. 
mechanism  of,  123. 

—  crico-arytenoid,  426. 
thyroid  426. 

—  of  the  elbow,  143. 

—  of  the  extremities,  upper,  135. 
lower,  153. 

—  of  the  face,  126. 

—  of  the  fingers,  in  general,  151. 

—  of  the  head,  with  vertebral  column. 

Cranio-vertebral. 

—  of  the  hip.     See  Coxo-femoral. 

—  humero-cubital,  141. 
•  movements  of,  142. 

■  of  jaw,  lower.     See   Temporo-maxillary, 


128. 


upper,  126. 

with  cranium,  126. 


•  of  the  knee,  162. 
mechanism  of,  166. 

•  of  larynx,  425. 

■  of  metacarpal  bones,  carpal  ends  of,  148. 

digital  ends  of,  149. 

with  carpus,  149. 

•  metacarpo-phalangal,  151. 
movements  of,  152. 

•  of  metacarpus  in  general,  148. 

■  of  metatarsal  bones,  tarsal  ends  of,  175. 
digital  ends  of,  175. 

'  mechanism  of,  175. 


■  metatarso-phalangal,  175. 
movements  of,  177. 

■  occipito-atlantoid,  116. 
•  mechanism  of,  122. 


axoid,  117. 


■  peroneo-tibial,  inferior,  167. 

middle,  168. 

superior,  168. 

mechanism  of,  168. 

■  of  the  pelvis,  154. 

mechanism  of,  156. 

'  phalangal,  of  fingers,  153. 

movements  of,  153, 


toes,  177 

movements  of,  177. 


Articulations,  radio-cubital,  mechanism  of,  144. 

inferior,  142, 

movements  of,  144. 

— middle,  143. 

movements  of,  143. 

— —  superior,  142. 

•  movements  of,  144. 


•  sacro-coccygeal,  120. 

iliac,  154. 

sciatic,  155. 

vertebral,  120, 

•  scapulo-humeral,  138. 
-—-  movements  of,  139. 

•  of  the  shoulder,  135. 

■  sterno-clavicular,  136. 

mechanism  of,  137. 


■  syndesmo-odontoid,  117. 
'  tarsal,  in  general,  170. 

•  mechanism  of,  173 


of  first  row,  171. 

of  second  row,  171. 

movements  of,  173. 

of  two  rows  together,  172. 

movements  of,  173. 

--  tarso-metatarsal,  in  general,  174. 

movements  of,  173. 

in  particular,  173. 

—  temporo-maxillary,  128. 

•  mechanism  of,  129, 


•  of  the  thorax,  130. 

'  mechanism  of,  132. 
■  movements  of,  134. 


■  thyro-hyoid,  425. 


tibio-tarsal,  168. 

mechanism  of,  169, 170. 

tracheo-cricoid,  426, 

of  the  vertebral  column,  115. 

mechanism 

121-123. 
movements 

122. 


of, 


■  of  the  vertebris  with  each  other,  115. 

bodies  of,  115. 

articular  processes  of,  116. 

laminae  of,  116. 

spinous  processes  of,  116. 

-^— ^— — —  peculiar,  1 16. 

■  of  the  wrist,  145.    See  Radio-carpal 


Astragalus,  100, 

Atlas,  23, 

Auditory  process,  44. 

meatus,  internal,  44. 

external,  44, 

nerve.     See  Nerve,  portio  molHt. 
Auricle  or  auricula  of  ear,  666.    See  Ear. 
Auricles  of  heart.     See  Heart. 
Auricular  surface  of  os  coxse,  91. 
Axis  (vertebra), 24, 

Basilar  process,  34, 
groove,  35. 
Bicipital  groove,  78, 

tuberosity,  81, 


Bi-parietal  suture,  46, 
Biventer  cervicis,  205, 

maxiOae  inferioris,  245, 


Bladder,  440. 

bas-fond  of,  442. 
coats  of,  442. 
development  of,  443. 
functions  of,  444. 
fundus,  inferior,  442, 

superior,  or  summit.  443. 


—  ligaments  of,  anterior,  441, 
■  posterior,  441. 


sacculated  and  fasciculated,  444. 

sphincter  of,  443. 

structure  of,  443. 

trigone  of,  443. 

uvula  of,  443. 

■  vessels  and  nerves,  444, 


•j)ubic,  155, 

■  radio-carpal,  145, 

•  movements  of,  145 


-  cubital,  142. 


Bones  in  general,  5-18. 

-  arteries  of,  three  kinds,  14,  15. 

-  asymmetrical,  8. 

-  broad  or  flat,  9. 

diploe  of,  13. 

ossification  of,  17. 

structure,  internal,  13. 

tables  of,  13. 

vitreousi  35. 


880 


INDEX. 


flonei,  eavities  of,  9,  10. 

'■ articular,  10. 

alveolar,  10. 

cotyloid,  10. 

glenoid,  10. 

trochleae,  10 


non-articular,  10. 

canals  or  conduits,  iO. 

fosse,  10. 

furrows,  grooves,  or  chan- 
nels, 10. 

notches,  10. 

sinuses  or  cells,  10. 


Bones,  coronal,  35, 

costae.     See  Ribs. 
of  cranium,  33. 
cubital,  79. 
cuboid,  101. 
cuneiform,  carpal,  83. 

tarsal,  external,  102. 

internal,  102. 

middle,  103. 


ossification  of,  17. 


—  changes  in,  after  maturity,  18. 

—  chemical  composition  of,  14. 
--  description  of,  mode  of,  11. 

—  development  of,  15. 

cartilaginous  stage,  15. 

— mucous  stage,  15. 

osseous  stage,  16. 

symmetry  of,  17. 


■  direction  of,  absolute  and  relative,  7. 
•  eminences  of,  9. 

articular,  9. 

condyles,  9 

■  heads  and  necks,  9. 


-non-articular,  9 

apophyses,  9. 

epiphyses,  9. 

-  marginal,  18, 


-ossification  of,  16. 


•  lines  and  crests,  9, 

■  mammillary     process- 

es, 9. 

■  processes,  10. 

■  prominences,  9, 

•  spines  or  spinous  pro- 

cesses, 9. 

•  tuberosities,  9. 


—  foramina  of,  11. 

~  growth,  mode  of,  18. 

--  long,  8. 

extremities  and  shafts  of,  9. 

marrow  or  medulla  of,  10. 

medullary  canal  of,  10. 

membrane  of,  13. 


-structure  of,  internal,  10. 
•ossification  of,  16. 


~  nerves  of,  14. 

nomenclature  of,  6. 

number  of,  6. 

• nutrition  of,  18. 

ossific  points  of,  16. 

ossification  of,  16, 17. 

eminences  and  cavities  of,  17. 

■ three  kinds  of,  17. 

regions  of,  9. 

shape  and  symmetry  of,  8. 

short,  9. 

ossification  of,  18. 

structure,  internal,  of,  IS. 

situation  of,  general,  6. 

size,  weight,  and  density  of,  7. 

structure  of,  internal,  13. 

-microscopic,  11. 


—  of  ear,  673. 

—  epactal,  50. 

—  ethmoid,  40. 
development  of,  41. 

—  efface,  51. 

—  femur,  93. 

development  of,  95 

—  fibula,  98. 

development  of,  99. 

—  of  fingers.     See  Phalanges. 

—  of  foot,  99. 

—  of  forearm,  79,  80. 

—  frontal,  35. 
development  of,  36. 


•of hand,  82. 

■  of  haunch,  89. 

■  humerus,  78. 
development  of,  79. 


■  hyoid,  109. 
development  of,  111. 

■  ilium,  89. 

•  incus,  674. 

■  ischium,  89. 

■  of  jaw,  lower,  57. 
upper,  61. 


jugal,  54. 

lachrymal,  56. 

development  of,  56. 


•  of  leg,  96. 

•  lenticular,  674. 

•  malar,  54. 
-  development  of,  55. 


malleus,  673. 

maxillary,  inferior,  57. 

development  of,  58 

superior,  51. 

•  development  of,  53. 


substance  of,  areolar,  11. 

cancellated,  or  spongy,  11. 

■ compact,  11. 

reticulated,  11, 13. 


surfaces,  angles,  and  bordeni  of,  8, 

symmetrical,  8. 

torsion  of,  99. 

veins  and  lymphatics  of,  14. 

Bones  in  particular,  18-111. 

of  arm,  78. 

astragalus,  100. 

atlas,  23. 

development  of,  31. 

axis,  24. 

-  development  of,  31. 


—  calcaneum,  100. 

—  of  carpus  or  wrist,  82. 

development  of,  84. 

first  row  of,  83. 

second  row  of,  83. 

—  clavicle,  74. 
development  of,  75. 


coccyx,  20. 

development  oi,  31. 


■  of  metacarpus,  84. 

development  of,  85. 

: first,  85. 

second,  third,  and  fourth,  85. 

fifth,  85. 


■  of  metatarsus,  103. 

development  of,  104. 

first,  103. 

second,  third,  and  fourth,  103 

■  fifth,  103. 


•  nasal,  55. 
development  of,  56. 

•  navicular,  of  carpus,  83. 
>  tarsus,  101. 


•  occipital,  33. 

development  of,  34. 


•  orbicular,  674. 

•  OS  calcis,  100. 

carinse,  33. 

hyoides,  110. 

iimominatum,  I 


•  development  of,  90. 


-  magnum,  83. 

•  planum,  40. 

•  prorae,  and  os  puppis,  33. 
quadratum,  53 

■  unguis,  55 


-  ossa  triquetra,  or  Wormiana,  50 

-  ossicula  auditfis,  673. 
•  palate,  63. 

development  of,  54. 

■  parietal,  41. 

development  of,  42. 


'  patella,  95. 

development  of,  96. 

•  of  pelvis,  87. 

•  perone.     See  Fibula. 

■  phalanges  of  fingers,  86. 

•  development  of,  87 


■  pisiform,  83. 

■  of  pubes,  90. 

■  radius.  81. 


■  toes,  104. 

-  development  of,  104 


JXBBX 


881 


BoHtM,  radius,  development  of,  89. 

ribs,  67. 

— ^-^— ^  development  of,  68. 

false  and  true,  67. 

rotula,  95. 

sacrum,  26. 

-  development  of^  SS. 


scaphoid  of  carpus,  83. 
tarsus,  101. 


'  scapula,  75. 

'  development  of,  75. 


-  semilunar,  83. 
sesamoid,  96. 

of  foot,  176. 

of  gastrocnemius,  165. 

of  hand,  153. 

'  of  knee  or  patella,  06. 


of  shoulder,  73. 

sphenoid,  36. 

development  of^  38. 


-  spheno-occipital,  36. 

-  spongy.     See  Turbinaitd. 

-  sternum,  64. 

development  of,  65. 

-  styloid,  43. 

-  of  tarsus,  99. 

development  of,  103. 

first  row  of,  100. 

second  row  of,  101. 

temporal,  42. 

development  of,  44. 

mastoid  portion  of,  43. 

petrous  portion  of,  43. 

squamous  portion  of,  43. 


Condi,  for  anterior  muscle  of  malleus,  679. 

—  arachnoid,  of  Bichat,  978. 

—  carotid,  43. 

—  for  chorda  tympani,  67S. 

—  crural,  310. 

—  dental,  inferior,  50 

—  of  Fontana,  656. 

—  godronn6,  661. 

—  hyaloid,  661. 

—  incisive,  52. 

—  infra-orbital,  51. 

—  inguinal,  306. 

—  for  internal  muscle  of  malleus,  43,  679. 

—  of  Jacobson,  671. 

—  maxillary,  superior,  51. 
inferior,  60. 


—  medullary  of  long  bones,  13. 

—  nasal,  653. 

—  of  Nuck,  465. 

—  palatine,  anterior,  53. 
posterior,  M. 


•  of  thigh,  93. 

•  of  thorax,  64. 
'  tibia,  96. 

development  of,  98 

'  of  toes.     See  Phalanges. 

■  trapezium,  63. 

■  trapezoid,  83. 

'  turbinated,  ethmoidal,  41. 

inferior,  56. 

'  development  of,  56. 


middle,  41. 
sphenoidal,  37. 
superior,  41. 


tympanic,  45. 

ulna,  79. 

development  of,  81. 

unciform,  83. 

of  vertebral  column.    See  Vertebra,  Vertebra, 

and  Vertebral  Column. 

vomer  or  ploughshare,  57. 

— '         development  of,  S7. 

Wormian,  50. 

zygomatic,  54. 

Borsa  appiattita,  706. 

Brain.     See  Cerebrum,  Cerebellum,  IsthmtU,  and  Me- 

dulla  Oblongata. 
Bronchi,  417. 

structure  of,  420. 

Bronchia  or  bronchial  tubes,  418. 

relations  of,  with  lobules,  418. 

structure  of,  420. 

Bronchial  arteries,  420. 

ultimate  distribution,  490 

glands  (lymphatic),  430. 

tubes,  418. 

veins,  420. 

ultimate  distribution,  430 


mucous  membrane,  342. 

characters  of,  343. 


fiucco-labial  furrow,  326 

Bulbs  of  fornix,  or  corpora  albicantia,  728. 

Bulbus  arteriosus,  494. 

Bursa  synovial  of  tendo  Achillis,  283. 

of  ligamentum  patella,  164. 

over  patella,  311. 

Bursa  mucosse  (so  called),  175. 

synovial,  175. 

around  eyeball,  649. 

near  shoulder  joint,  143. 

" hip  joint,  161. 

knee  joint,  164. 

•  sub-cutaneous,  630. 

Calamus  scripforius,  703. 

Calcaneum,  100. 

Calcar,  736. 

Canal,  alimentary     See  Alimentary  Canal. 


of  Petit,  661. 

pterygo- palatine,  38. 

pterygoid,  38. 

sacral,  27. 

for  tensor  tympani  muscle,  43,  87L 

tympanic,  673. 

vertebral,  30. 

vidian,  38. 

of  Wirsung,  401. 

zygomatic,  55. 
Canals  of  bones,  12. 

dental,  superior,  51. 

lachrymal,  652. 

palatine,  accessory,  54. 

semicircular,  576.    See  Semicireuha-  Cmak. 
Canine  fossa,  51. 
Canthi  of  eyelids,  647. 
Capitula  laryngis,  426. 
Capitulum  costae,  68. 

ligaments.    See  Ligament 

Capsule  of  GUsson,  478. 
lens,  663. 


Capsules,  synovial,  1 14. 

of  particular  joints. 


See  those  joints. 


supra-renal,  445.    See  Supra-renal  Capsule*. 

atrabiliary,  445. 


Caput  coecum  coli,  37l 

gallinaginis,  464< 
Cardia,  442. 

nerves 


Carotid  arteries. 
-—  nerves. 


See  Nerves. 
See  Arteries. 
See  Nerves. 
See  Arteries. 


Carpal  arteries. 
Carpus,  bones  of,  82. 

bones  of  first  row  of,  83. 

compared  with  first  t 

of  tarsus,  108. 

second  row  of,  83. 

compared  with  second! 

of  tarsus,  108. 


■  compared  with  tarsus,  107. 
'  sheaths  for  tendons  on,  316. 


Cartilage,  chemical  composition  of,  174. 

cricoid,  423. 

of  ear,  666. 

ensiform,  65. 

structure  of,  174. 

thyroid,  433. 

xiphoid,  65. 
Cartilages,  articular,  111. 

characters  of,  111. 
structure  of,  174. 


—  chemical  composition  of,  174. 


■  arytenoid,  424. 

-  costal,  69. 

articulations  of,  133. 

■  falciform,  of  knee,  162. 
'  inter-articular,  1 12. 
structure  of,  174. 

temporo-maiillary,  128. 

-^-— ~^>— .-.-  acromio-clavicular,  136 
stemo-clavicular,  137. 

of  wrist,  143. 

of  knee  joint,  168. 


'  inter-osseous,  113. 

•  structure  of,  174. 


5T 


■  of  larynx,  423. 

ossification  of,  435. 

of  nose.     See  Nose. 


882 


INDEX. 


Cartilages,  semilunar,  of  knee,  163. 

tarsal,  of  eyelids,  647. 

Caruncula  lachrymalis,  647. 

Carunculx  myrtiformes,  468. 

Cauda  equina,  770. 

Caudal  extremity  of  helix  and  antihelix,  667. 

Cavernous  body.     See  Corpus  Cavemosum. 

Cavity,  coronoid,  80. 

cotyloid,  88. 

digital  or  ancyroid,  947. 

glenoid,  of  scapula,  76. 

temporal  bone,  43. 

olecranoid,  80. 

of  omentum,  478. 

sigmoid,  great  and  lesser,  81. 

supplementary,  of  temporo-maxiUary  articula- 
tion, 128. 

'  of  shoulder  joint,  139. 


•  trochanteric,  95. 


Cavities,  articular,  10. 

supplementary,  128. 

orbital,  62. 

glenoid,  of  tibia,  97. 

•  nou-articular,  11. 


Cells  of  bones,  11. 

ethmoidal,  42. 

frontal,  36. 

sphenoidal,  39. 

Cellular  tissue,  298. 

lymphatics  of,  613. 

Central  foramen  of  retina,  661. 
Centrum  ovale  minus,  736. 

of  Vieussens,  736,  752. 

semicirculare  geminum,  746. 

Cerebellar  arteries.     See  Arteries. 

veins.    See  Veins. 

Cerebellum,  715. 

arbor  vitie,  lateral  and  median,  721. 

commissures  of,  723. 

comparative  anatomy,  724. 

corpus  callosum  of,  711. 

dentatum  or  rhomboideum,  721. 

development  of,  724. 

falx  of,  684. 

fasciculi,  converging  and  diverging,  724. 

fibres  of,  formative  and  uniting,  724. 

fissure  of,  median,  717. 

furrovrs  of,  717. 

Gall's  views  of,  724. 

ganglia  of,  721. 

general  view  of,  724. 

internal  structure  of,  718. 

examined  by  hardening,  722. 

• ■ sections,  721. 

water,  722. 


Cerebrum,  anfractuosities,  uses  of,  735. 

arbor  vitae  of,  750. 

base  of,  727. 

lateral  regions,  731. 

median  excavation  of,  727. 

region,  727. 

commissures,  753.     See  Commissur* 

comparative  anatomy  of,  757. 

convolutions  or  gyri,  732. 

of  digital  cavity,  733. 

inferior  surface,  733. 

superior  surface,  734. 

internal  surface,  733. 


■  structure  of,  755. 
•  uses  of,  734. 
Gall's  views  of,  754 


•  crura  of,  723. 

•  development  of,  756. 

•  falx  of,  684. 

-  fibres  of,  formative  or  diverging,  752. 
radiating,  754. 

uniting  or  converging,  752. 

general  idea  of,  754. 

-  fissure,  longitudinal,  726. 

Sylvian,  727. 

transverse,  great,  727. 


'  ganglia  of,  752. 
hemispheres  of,  726. 

•  nuclens  of,  749 


•  internal  structure  of,  735. 

examined  by  hardening,  75ff. 

sections  of,  736. 

■— water,  750 


laminae  and  lamellae  of,  717. 
structure  of,  722  (note). 

lobe,  sub-peduncular,  718. 

lobes,  lateral  and  median,  717. 

lobule  of  circumference,  718. 

medulla  oblongata,  718. 

pneumogastric  nerve,  718. 

lobules  or  segments,  717. 

medullary  centre  of,  722. 

peduncles  of  inferior,  704,  722. 

middle,  710,  722. 

superior,  711,  722. 

sections  of,  720. 

—  horizontal,  722. 


vertical,  721. 

size  and  weight  of,  716. 
substances,  gray,  white,  and  yellow,  721. 
surface,  upper,  716. 
lower,  717. 


-  tentorium  pf,  684. 

ventricle  of.     See  Ventricle,  fourth. 

Cerebr  jI  axteries.     See  Arteries. 
— —-  nerves.     See  Nerves,  cranial. 

peduncles,  substance,  &c.    See  Cerehrvm. 

veins.     See  Veins. 

Cereiro-spinal  axis,  681. 

. •  divisions  of,  682. 

membranes  of,  682.   See  Arachnoid, 

Dura  Mater,  and  Pia  Mater. 
Cerebrum,  725. 

anfractuosities  or  sulci,  732. 

of  digital  cavity,  733. 

inferior  surface,  733. 

internal  surface,  734. 

superior  surface,  734. 


Foville's  views  of,  755. 

Gall's  views  of,  751. 

general  idea  of,  753. 

Mayo's  views  of,  754 

Rolando's  views  of,  759. 

■  lobes  of,  731  (note),  735. 

•  medullary  centres  of,  737. 

•  peduncles  of,  710. 

transverse  fibres  of,  711. 

course  of,  in  brain,  753. 

■  structure  of,  713. 


■  section,  vertical  median,  748. 
-Willis's,  750. 


•  sections  of  horizontal,  736. 

vertical,  transverse,  750. 

general  remarks  on,  751 


■  size  and  weight,  725. 

compared  to  that  of  ceio 

bellum,  725. 
•  substance,  gray  or  cortical,  702  (note). 

•  white  or  medullary,  702  (note^ 


■  surface,  inferior,  or  base,  727. 

■  superior,  or  convex,  727. 


unfolding  of,  by  Gall,  753. 
ventricles  of,  753.     See  Ventricle. 
Cervical  arteries.     See  Arteries. 


■  ganglia.     See  Ganglion. 

■  nerves.     See  Nerves. 

■  plexuses.     See  Plexuses. 
vertebrce.    See  Vertebra  and  Vertebra 


Cervix  uteri,  465. 
Cheeks,  328. 

development  of,  328. 

muscles  of,  328. 

structure  of,  328. 

vessels  of,  328. 


Chemical  composition  of  tissues,  &c.    See  thoM  t» 

sues,  &c. 
Chiasma,  optic,  728,  819. 
Chorda  tympani  nerve,  836. 

-  canal  for,  672. 


Chorda  tendineae,  483. 

vocales,  426. 

inferior  or  true,  427. 

superior  or  false,  427. 


Chorion,  631. 

Choroid  coat  of  eye,  657. 

structure  of,  657. 


•  pigment,  659. 

■  plexuses,  747.    See  Plexuses. 

■  veins  of  brain,  586. 
eye,  657. 


Ciliary  body,  crown,  or  disc,  656. 
canal,  656. 

circle,  ligament,  or  ring,  656. 

processes  of  the  choroid  coat,  656 

zone  of  Zinn,  657. 


INDEX. 


883 


OfrcteofWilliB,  727. 
Circular  sinus  of  Ridley,  587. 
Circumflex  arteries.     See  Artenei, 

veins.     See  Veins. 

Clavicle,  74. 
Clitoris,  471. 

artery  of,  558. 

crura,  glans  and  prepuce  of,  471. 

ligaments  and  muscles  of,  471. 


—  nerve  of.  807. 


Cochlea,  677. 

aqueduct  of,  679. 

axis,  columella,  or  modiolus  of,  678. 

lamina  gyrorum,  or  tube  of,  678. 

• spiralis  of,  membranous  and  osseous, 

678 


nerves  of,  681. 
■  scalae  of,  tympanic  and  vestibular,  677. 


Cochleariform  process,  44. 
Coccygeal  vertebrse,  18,  27. 
Coccyx,  27. 
Ccecal  appendix,  373. 
Cacum,  371. 

appendix  vermiformig  of,  373. 

development  of,  383. 

• internal  surface,  373. 

structure,  378. 

Collateral  arteries.     See  Arteries. 

nerves.     See  Nerves. 

Colon,  373. 

arch  of,  374. 

ascending,  374. 

— — -  descending,  374. 
— —  development  of,  384. 

' flexures  of,  iliac  and  sigmoid,  371. 

— —  internal  surface  of,  376. 

longitudinal  bands  of,  374. 

lumbar,  left  and  right,  374. 

structure  of,  378. 

transverse,  375. 

Columella  of  cochlea,  708. 

valve  of  Vieussens,  712. 

Columnce  cameae,  483. 

of  rectum,  377. 

Columns,  fronto-nasal,  127. 

zygomato-jugal,  127. 

jugal,  127. 

pterygoid,  127. 

• of  face,  127. 

of  vagina,  469. 

•  of  spinal  cord.    See  Spinal  Cord. 

Comites,  arteriae.     See  Arteries,  satellite. 

nervi.     See  Nerves,  satellite. 

venae,  572. 

Commissura  mollis,  740. 
Commissure,  anterior,  of  brain,  741. 

antero-posterior,  753. 

external  and  internal,  of  eyelids,  647. 

■  great  transverse,  of  brain,  735. 
of  lips,  326. 

longitudinal,  of  brain,  or  fornix,  737. 

optic,  729. 

'  of  pineal  body,  742. 

posterior,  of  brain,  742. 

soft  or  gray,  741. 

of  spinal  cord,  anterior,  698. 

gray  and  white,  699. 

at  Sylvian  fissure,  746. 

Commissures  of  brain,  742.  See  Commissure. 
Common  mass  of  posterior  spinal  muscles,  201. 
Communicating  arteries.     See  Arteries. 

nerves.     See  Nerves. 

Comparison  of  arm-bone  with  thigh-bone,  105. 

■ arteries  of  upper  and  lower  extremities, 

572. 

bones  of  upper  and  lower  extremities, 

105. 

carpus  and  tarsus,  107. 

development  of  upper  and  lower  extrem- 
ities, 109. 

enamel  and  ivory  of  teeth,  183. 

first  rows  of  carpus  and  tarsus,  108. 

hand  and  foot,  107. 

■ leg  with  forearm,  105. 

lower  parts  of  radius  and  tibia,  107. 

metacarpus  and  metatarsus,  108. 

■  nerves  of  upper  and  lower  extremities, 

815. 

permanent  and  temporary  teeth,  187. 

phalanges  of  fingers  and  toes,  109. 


Comparison  of  second  rows  of  caipus  and  tarsus,  108. 

shoulder  with  pelvis,  105. 

■ teeth  and  bones,  177. 

epidermoid  appendages,  177 


upper  and  lower  molar  teeth,  181 

upper  parts  of  ulna  and  tibia,  107, 

Compressor  muscles.    See  Muscles. 
Conarium,  742. 
Concha  of  ear,  I 


■  tragic  fossa  of,  I 
■  nose,  inferior,  56. 

middle,  41. 

■  superior,  41. 


Concha,  ethmoidal,  41. 
Condylarthrosis,  characters,  &c.,  114. 
Condyle,  10. 

humeral,  78. 


Condyles,  occipital,  34. 

of  lower  jaw,  58. 

femur,  95. 

tibia,  97 


Condyloid  foramen,  anterior,  34. 

— posterior,  34. 

fossa,  34. 

Confluences  of  the  sinuses,  588. 
Coni  vasculosi  testis,  452. 
Conjunctiva,  648. 

Constrictor  muscles.     See  Muscles. 
Conus  arteriosus,  481. 
Convolutions  of  brain.    See  Cerebrum. 
small  intestines,  364. 


Coracoid  process,  76. 

Cordiform  tendon  of  diaphragm,  213. 

Cornea,  opaque,  655. 

transparent,  655. 


Comicula  laryngis,  424. 
Comu  Ammonis,  745. 
Cornua  of  hyoid  boue,  109. 

lateral  ventricle.    See  Ventrieh 

styloid,  109. 

thyroid  cartilage,  424. 

Corona  ciliaris,  656. 

radians  of  Reil,  755. 

of  glans  penis,  461. 

Coronal  bone,  35. 

Coronary  arteries.     See  Arteries. 

ligaments.     See  Ligaments. 

veins.     See  Veins. 


Coronoid  cavity,  80. 

process  of  lower  jaw,  58. 
ulna,  80. 


Corpora  albicantia,  728. 

structure  of,  738. 


Arantii,  486. 
bigemina,  712. 
lutea,  462. 
mammillaria,  728. 
olivaria,  or  ovata,  706. 
quadrigemina,  712. 
restiformia,  707. 
Corpus  bulbosum,  461. 

artery  of,  558. 

nerve  of,  806. 


—  callosum,  artery  of,  529. 

■  —  bourrelet  or  cushion  of,  731 

of  cerebellum,  711. 

extremity,  anterior,  737. 

posterior,  731. 


■  genu  or  knee,  737. 
-  peduncles  of,  730. 

■  reflected  portion,  anterior,  730. 

■  rostrum  or  beak,  737. 
•  convolution  of,  733. 

■  ventricle  of,  737. 

■  longitudinal  tracts  of,  737 

■  fibres  of,  753. 


—  cavernosiun  penis,  455. 

1 crura  of,  455. 

nerves,  456. 

structure,  455. 

■  vessels,  456. 


■  dentatum  cerebeUi,  721. 
meduUae,  705. 


fimbriatum,  739. 

—  uteri,  464. 


geniculatum  externum,  728. 
internum,  712. 


Highmori,  450. 
luteum,  462. 
•  mucosuiD  of  skin,  635- 


INDEX. 


Corpus  papillare  of  skin,  689. 

psalloides,  738. 

.  reticulare  of  skin,  635. 

I spongiosum  urethrse,  460. 

striatum,  744. 

fibres  of,  753. 

lobule  of,  731. 

rein  of,  745. 

Costal  cartilages,  69. 
Costa,  67.    See  Ribs. 

of  scapula,  76. 

Cotyloid  cavity,  88. 

cavities  in  general,  11. 

Crania,  national,  44. 

Cianial  nerves,  in  general.    See  Nerves. 

in  particular.    See  Nerves. 

— —  ganglia.     See  Ganglia. 

arachnoid.     See  Arachnoid. 

dura  mater.     See  Dura  Mater. 

Cranium,  aponeuroses  of,  299. 

area  of,  45. 

articulations  of,  125. 

—  base  of,  exterior  of,  45. 

interior  of,  46. 

———  bones  of,  34. 

circulation  of,  arterial,  531. 

—  venous,  562. 


-  development  of,  50. 

-  external  surface  o.'',  45. 

■  lymphatic  system  of,  627. 

-  in  general,  45. 

-  internal  surface  of,  46. 

-  mechanism  of,  126. 

■  regions  of,  45. 

■  sutures  of,  in  general,  154. 
particular.    See  Sutures. 


-varieties  of,  45. 
-  vault  of,  45. 


Crest  of  ilium,  89. 

pubes,  89. 

tibia,  97. 

urethra,  459. 

Crests,  occipital,  35. 

Cribriform  plate  of  ethmoid  bone,  40. 

Crijtta  gaUi,  40. 

ilii,  89. 

vestibuli,  676. 

Crura  of  clitoris,  471. 

corpus  cavemosum,  455. 

diaphragm,  212. 

cerebri,  711. 

Crural  arch,  309. 

ring,  310. 

septum,  310. 

Crust  of  cerebral  peduncles,  713  (note). 

Crusta  petrosa,  182. 

Crypts  of  Lieberkuhn,  369. 

Cuneiform  bone  of  carpus,  83. 

Cutaneous  nerves.    See  Nerves. 

Cuticle,  633. 

Cutis,  or  cutis  vera,  631. 

anserina,  630. 

Cystic  duct,  397. 
Cijslis  fellea,  396. 

Uo'tns,  446. 

tissue  of,  446  (note). 

Deltoid  impression,  78. 
Wfrt/a;  arteries.     See  Arteries. 
— —  canal,  inferior,  57. 

canals,  superior,  31. 

nerves.     See  Nerves, 

veins.    See  Veins. 

Dentata  (vertebra),  24. 

Denies.     See  Teeth. 

Depressor  muscles.    See  Muscles. 

Development  of  particular  bones,  organs,  or  parts 

body.     See  those  bones,  organs,  &c. 
Diaphragm,  218. 
Diarthroses,  114. 
Digastric  fossa,  43. 

groove,  43. 

Digestive  apparatus,  general  view  of,  3. 
D^tal  arteries.    See  Arteries. 

nerves.     See  Nerves. 

Diploe,  14. 

Diploic  canals.  591. 

veins,  585,  591. 

Dissection  of  different  parts.     See  those  parts. 
Oorsal  arteries.     See  Arteries. 


Dorsal  ligaments.    See  Ligament*. 

nerves.     See  Nerves. 

veins.     See  Veins. 

vertebrae.     See  Vertebra  and  Verttirtt. 

Dorsum  ilii,  or  external  iliac  fossa,  88. 

lingua;,  337. 

manus,  82. 

nasi,  64l. 

——pedis,  99. 

Duct,  common  biliary,  398. 

'        internal  surface,  399. 

structure,  399. 


•  cystic,  397. 

structure,  399. 

'  ejaculatory,  452. 
'  hepatic,  395. 

internal  surface,  3W. 

structure,  399. 


—  lymphatic,  right,  619. 

—  nasal,  653. 

—  pancreatic,  402. 

—  parotid,  341. 

—  Stenonian,  341. 

—  thoracic,  618. 
■  right,  619. 


Warthonian,  342. 

Ducts,  biliary,  398. 

lactiferous  or  galactophorona,  473. 

prostatic,  458. 

of  Rivinus,  342. 

Ductus  arteriosus,  500. 

communis  choledochus,  398. 

ejaculatorius,  452. 

venosus,  600. 

Duodenum,  361. 

curvatures  of,  362. 


~  glands  of,  370. 
—  lymphatic  glands  of,  625. 
•  structure  of.     See  Smalt  Intestine. 


Dura  mater,  682. 

cranial  portion  of,  683. 
cranial  nerves  of,  686. 

sinuses  of,  584. 

structure  of,  685. 

uses  of,  686. 

vessels  of,  ( 


dissection  of,  682. 
spinal  portiou  of,  686. 
vessels  of,  687. 


Ear,  auricle  of,  666. 

cartilage  of,  666. 
ligaments  of,  667. 

muscles  of,  extrinsic.     See  MtudUf 
auricular. 

intrinsic,  668. 


skin  of,  668. 

vessels  and  nerves,  668. 

•  drum  of.     See  Tympanum. 

external.     See  auricle  and  meatus  of. 

general  view  of,  666. 

internal,  or  labyrinth  of     See  Labyrinth. 

meatus  of  external,  668. 

cartilaginous  and  fibrous  portion  of,  688. 

—  glands  of,  669. 

osseous  portion  of,  44. 


—  skin  of,  6. 

—  internal,  44. 
.  bottom  of,  680. 


middle.    See  Tympanum. 

ossicula  of,  673. 

movements  of,  674. 
muscles  belonging  to,  674. 

tympanum  of.     See  T)/mpanum. 

vessels  of,  680. 
Eighth  cranial  nerve.    See  Nerves,  glosso-pharyngsal, 

pneumogastric,  and  spinal  accessory. 
J^aeulatory  duct,  452. 
Elastic  tissue,  structure  of,  174. 

chemical  composition  of,  174. 


ligaments,  general  characters  of.  112. 
■  of  vertebrsB,  115. 


Elbow-joint,  143. 
Eminence,  jugular,  34. 

nasal,  35. 

frontal,  35. 

ilio-pectineal,  89. 

hypothenar,  261. 

thenar,  260. 

unciform  of  lateral  ventricle,  730 


INOB2. 


88$ 


Eminenlia  collateralis,  746. 
EminentitB  natiformes,  712. 

testiformes,  712. 

Enamel  of  teeth.     See  Teeth. 
Enarlhroses,  114. 

Encephalic  nerves.    See  Nerves,  craniai. 
Encephalon,  arteries  of,  in  general,  535. 

isthmus  of.     See  Isthmus. 

£mio-cardium,  488. 

lymph,  680. 

Ensiform  process,  cartilage  or  appendix,  65. 
Epactal  bones,  50. 
Epicondyle,  79. 
Epidermis,  633. 
Epididymis,  451. 

globus  major,  451. 

—  minor,  451. 


-  structure,  451. 


Epigastric  region,  352. 
Epiglottis,  425. 
Epiploon,  i78.    See  Omentum. 
Epithelium  ciliated,  323. 

columnar,  323. 

squamous,  323. 

of  particular  membranes.     See  those  mem- 
branes. 
Epitrochlea,  80. 

Erectores  muscles.    See  Mutdt*. 
Ergot,  736. 
Ethmoid  bone,  40. 
Ethmoidal  bulb,  818. 

cells  or  sinuses,  40. 


—  fossa,  48. 

groove,  40. 

labyrinth,  40. 


EustacJaaa  tube,  or  trumpet,  672. 

cartilaginous  and  fibrous  portion,  672. 

mucous  membrane,  673  (note}. 

osseous  portion,  44,  672. 

Extensores  muscles.     See  Muscles. 
Extremities,  lower,  aponeuroses  of,  306. 

articulations  of,  153. 

arteries  of,  557. 

7 bones  of,  87. 

development  of,  104. 

lymphatic  system  of,  619. 

nerves  of,  797. 

veins  of,  603. 

upper,  aponeuroses  of,  315. 

arteries  of,  531. 

■        articulations  of,  135. 

bones  of,  74. 

——— development  of,  87. 

■  lymphatic  system  of,  628. 

nerves  of,  781. 

•^— ^— veins  of,  593. 

upper  and  lower,  arteries  of,  compared,  572. 

bones  of,  compared,  105. 

— — ^— —  developmont   of,    compa- 
red, 109. 
aeires  of,  oMnpared,  815. 


Eye,  645. 

appendages  of,  646. 

— —  brows,  646. 

— —  chamber  of,  anterior,  658. 

■ posterior,  658. 

globe  of,  654. 

humours  of,  aqueous,  664. 

crystalline,  662. 


■  vitreous,  66l. 

■  lashes,  646. 
'  Uds.  646. 

cartilages  of,  647. 

commissures  or  canthi,  647. 

glands,  648. 

mucous  membrane,  647. 

muscles  of,  647. 

uses  of,  647. 

vessels  and  nerves,  648. 

■  membranes  of,  654. 

of  aqueous  humour,  655. 

arachnoid  of,  656  (note). 

•  capsule  of  lens,  662. 

choroid  coat,  656. 

cornea,  655. 

hyaloid,  661. 

■ —  iris,  657. 

Jacob's,  661. 

pupillary,  659. 

retina,  660. 


Eye,  membrane,  Raysch's,  659. 

sclerotic  coat,  654. 

of  vitreous  humour,  661. 

muscles  of,  oblique,  651. 

recti,  or  straight,  651. 

action  of,  651 


nerve  of.     See  Nerve,  optic. 

pigment  of,  660. 

vessels  of,  665. 

Face,  area  of,  46. 

bones  of,  51. 

cavities  of,  62. 

circulation  of,  arterial,  530. 

venous,  593. 


'  development  of,  general,  63. 

regions  of,  63,  64. 


in  general,  60. 

lymphatic  system  of,  626. 

movements  of,  238. 

muscles  of,  231. 

regions  of,  60. 

Facial  angle  of  Camper,  45. 

nerve.     See  Nerve,  portio  dura. 

Fallopian  aqueduct,  43. 

hiatus,  44. 

ligament,  302. 

tubes,  463. 

fimbriae  of,  463. 

structure  and  uses  of,  463. 


Fascia. 


Fall  of  umbilical  vein,  475. 

cerebelli,  684. 

cerebri,  684. 
See  Aponeurosis. 

—  cervical,  209. 

—  cremasteric,  302. 

—  cribriform,  309, 621. 

—  dentata,  476. 

—  iliac,  302. 

—  infundibuliform,  of  cord,  302. 

—  intercolumnar,  of  inguinal  ring,  301. 

—  lata,  309. 

iliac  portion,  310. 

pubic  portion,  311. 

structure,  311. 


obturator,  308. 

propria  (sub-peritoneal  fascia),  803-30$ 

recto-vesical,  308. 

spermatic,  304, 

superficial,  297,  630. 

tensor  muscles  of,  294. 

transversalis,  305. 

Fasciculi,  muscular,  193. 

of  medulla.     See  MeduUa. 


Fauces,  arches  of,  330. 
isthmus  of,  330. 
pillars  of,  330. 


Femur,  93. 
Fenestra  ovalis,  670. 

rotunda,  and  its  fossa,  671 


Fibres,  muscular,  involuntary,  324. 
voluntary,  193. 


nervous,  767. 
Fibrous  tissue,  298. 
fV6ro-cartilage  of  epiglottis,  425. 
cartilages,  177. 

of  particular  joints.     See  those  joiata 

FOula,  98. 

Fifth  cranial  nerve.    See  Nerve,  trifacial 
Filaments,  muscular,  193. 
nervous,  767. 


FiOet,  712. 

FinU>ri<B  of  Fallopian  tubes,  463. 

Fingers,  86. 

phalanges  of,  86. 

— >-  and  toes,  phalanges  of,  compared,  130. 
First  cranial  nerve.    See  Nerve,  olfactory. 
Fissure,  Glasserian,  43. 

glenoidal,  43. 

incisive,  53. 

orbital,  63. 

pterygo-maxillary,  55. 

spheno-maxiUary,  39,  52,  55. 

-  sphenoidal,  39. 

Sylvian,  730. 

Fissures  of  brain,  liver,  etc.    See  tbose  oigani* 

Flexor  muscles.     See  Muscles. 

Flocculus,  718. 

Fluid,  ventricular,  744. 

of  Scarpa,  680. 


886 


INDEX. 


Fluid,  sub-arachnoid,  144. 
Folds,  aryteno-epiglottid,  433. 

glosso-epiglottid,  336. 

pharyngeo-epiglottid,  426. 

Follicles,  dental,  184. 
of  Goodsir,  183. 

intestinal.     See  Intestines. 

Lieberkuhn's,  379. 

sebaceous,  635. 

— solitary,  370. 

of  stomach,  360. 

tubular,  360. 

uterine,  471. 

Fontanelles  of  scull,  49. 
Foot,  bones  of,  99. 

compared  with  hand,  106. 

Foramen,  of  Bichat,  688. 

ofBotal,  486. 

centrale  of  retina,  660. 

caecum  of  frontal  bone,  36. 

Morgagni  {in  tongue),  333. 

'  medulla  oblongata,  703- 


condyloid,  anterior,  34. 
posterior,  34. 


infra-orbitary,  59. 
lacerum  superius,  39. 

posterius,  44,  47,  49. 

anterius,  47. 


magnum,  34. 
mastoid,  43. 
mental,  57. 
of  Monro,  740. 
nutritious  of  humerus,  78. 
ulna,  79. 


radius,  81. 

femur,  93. 

tibia,  96. 

fibula,  99. 

obturator,  88. 
occipital,  34. 

optic,  37. 

orbital,  internal  anterior,  36. 
posterior,  36. 


ovale  of  heart,  487. 

■  sphenoid  bone,  38. 


parietal,  42. 

rotundum,  38. 

spheno-palatine,  54. 

spheno-spinosum  or  spinosun,  38. 

Etylo-mastoid,  43. 

superciliary,  36. 

supra-orbitary,  36. 

vertebral,  20,  21. 

of  Winslow,  476. 

Foramina  Thebesii,  488. 

malar,  54. 

of  bones,  11. 

inter-vertebral,  20,  30. 

posterior,  775  (note). 

sacral,  27. 

Forearm,  bones  of,  79. 

compared  vdth  leg,  105. 

Fornix,  739. 

• bulbs  of,  740. 

pillars  of  anterior,  739. 

— posterior,  740. 

Fossa,  amygdaloid,  331. 

canine,  51. 

digastric,  43. 

ethmoidal,  48. 

iliac,  external,  88. 

internal,  88. 

infra-spinous,  76. 

ischio-rectal,  309. 

jugular,  43. 

lachrymal,  36. 

mental,  58. 

myrtiform,  49. 

navicularis  of  urethra,  461. 

vulva,  470. 

ear,  670. 


■  ovalis  of  heart,  488. 

■  parietal,  43. 

■  perineal,  309. 

■  pituitary,  37,  48. 

•  pterygoid,  38. 

■  scaphoid.    See  Navicularis. 

■  spheno-maxillary,  60. 

•  sub-lingual,  57,  60. 

■  sub-maxillary,  57,  60. 


Fossa,  ffub-pynmidal,  671. 

sub-scapular,  75. 

supra-sphenoidal,  37. 

supra-spinous,  76. 

temporal,  47. 

zygomatic,  60. 
Fossa  of  bones,  II. 

-  condyloid,  34. 

-  frontal,  36. 

-  internal  iliac,  91. 

-  nasal,  63. 

-  middle  lateral,  or  spheno-temporal,  48 

-  occipital,  35. 
Fourchette  of  sternum,  65. 

vulva,  470. 


Fourth  cranial  nerve.  See  Nerve,  pathette. 
Fovea  hemispherica,  676. 
-  semi-elliptica,  676. 
Frcenum  labii,  324. 

lingus,  336. 

prsputii,  455. 


Frontal  bone,  35. 

cells  or  sinuses,  37. 
eminence,  35. 
fosss,  36. 


Fronto-JMgaH  suture,  48. 

maxillary  suture,  59. 
nasal  suture,  59. 
—  columns,  127. 


parietal  suture,  45,  47. 

sphenoidal  suture,  48. 

Fundus  of  stomach,  bladder,  Ac.     See  those  organ*. 
Furrow,  mylo-hyoidean,  57. 

mento-labial,  326. 

bucco-labial,  326. 


Furrows  of  heart  and  spinal  cord.    See  those  organa. 

Galactophorous  ducts,  473. 
Galea  capitis,  208. 
Gai2-bladder,  396. 

structure  of,  397. 


use  of,  400. 


Ganglia,  lymphatic.     See  Lymphatic  Glands. 
Ganglia,  nervous,  in  general.     See  Nerves,  ganglia  oj 
Ganglia,  nervous,  in  particular,  765. 

abdominal,  865. 

of  brain,  753. 


cervical,  sympathetic.     See  Ganglion. 

cranial,  765. 

•  sympathetic,  854. 


-  intercosttj,  765. 
■  lumbar,  sympathetic,  868. 
external    and    intemtl 

branches  of,  860. 

-  spinal  or  rachidian,  765. 

-  splanchnic,  765. 

-  sympathetic,  765. 

— —  connexions  of,  766. 

structure  of,  768. 


-thoracic,  864. 

external  branches,  864. 

'  internal  branches,  804. 


-vertebral,  761. 


Ganglion  of  Andersh,  843. 

annulare  (of  eye),  831. 

cardiac,  862. 

carotid,  856. 

of  cerebellum,  722. 


cervical,  inferior,  859. 

middle,  859. 

superior,  855. 

^ —  branches  of,  anterior,  857. 

. external,  858. 

inferior,  858. 

— internal,  858. 

——  superior,  856. 


■  ciliary,  830. 


—  Gasserian,  827. 

—  of  glosso-pharyngeal,  843. 

—  impar,  871. 

—  inter-carotid,  858. 

—  lenticular,  830. 

—  Meckel's,  831. 

—  naso-palatine,  831. 

—  ophthalmic,  and  branches,  830. 

—  otic,  and  branches,  837. 

—  petrosal,  843. 

—  of  pneumogastric,  845. 

—  of  Bibes,  857. 

—  of  root  of  hypoglossal,  823  (note). 


INDEX. 


887 


(hmglioH  of  root  of  spinal  accessory,  823. 

semilunar  abdominal,  866. 

of  fifth  nenre,  827. 

solar,  866. 

'         spheno-palatine,  and  branches,  831. 

sub-maxillary,  837. 

thoracic,  first,  859. 

thyroid,  859. 

Gasserian  ganglion,  827. 

Genial  processes,  58. 

Ginglymus,  angular  and  lateral,  114. 

Glabella,  35. 

*iland,  accessory,  of  parotid,  341. 

epiglottid  (so  called),  430. 

lachrymal,  652. 

• parotid,  340.     See  Parotid  Gland. 

pineal.     See  Pineal  Gland. 

pituitary,  729. 

prostate,  459. 

•  structure,  459. 

sub-lingiial.     See  Sub-lingual  Glana. 

sub-maxillary,  342.    See  Sub-maxillary  Gland. 

thymus,  415. 

•  thyroid,  433. 


Glands,  agminated,  370. 

arytenoid,  433. 

Brunner's,  370. 

buccal,  329. 

ceruminous,  669. 

conglobate  (lymphatic),  614. 

Cowper's,  460. 

duodenal,  370. 

epiglottid,  430. 

of  Havers,  113. 

—  in  knee,  163. 

intestinal.     See  Intestines. 

labial,  328. 

laryngeal,  432. 

lingual,  337. 

lymphatic,  in  general,  616. 

particular. 

Glands. 


Groove,  superior  petrosal,  44. 

of  torsion,  of  humertu,  78. 

Grooves  of  bones,  12. 

calcaneal,  100. 

carotid,  37. 

cavernous,  37. 

for  lateral  sinuses,  34. 

on  back  of  radius,  81. 

sacral,  92. 

of  spinal  cord.    See  Spinal  Cori, 

vertebral,  29. 

Gubemaculum  dentis,  189. 

testis,  44«. 


Gula,  344. 

Gulf  of  the  internal  jugular,  583, 

Gums,  329. 

HabentB  of  pineal  body,  742. 
Hamular  process  of  sphenoid  bone,  37. 
cochlea,  678. 


Hand,  bones  of,  82. 

compared  with  foot,  107. 

Hairs,  description  of,  general,  638. 

follicles  of,  638. 

structure  and  growth,  638  (note). 
Harmonia,  114. 
Harmonic  sutures,  114. 
Haunch  bone,  89. 
Heads  of  bones,  9. 

particular.    See  those  bonoa. 


See      Lymphatic 


mammary,  472. 

Meibomian,  648. 

molar,  329. 

odoriferous,  of  prepuce,  453. 

oesophageal,  352. 

of  Pacchioni,  585,  685. 

palatine,  329. 

Peyer's,  370. 

salivary,  340.    See  Salivary  Glands. 

solitary,  370. 

sudoriferous,  633. 

synovial  (so  called],  113. 

of  trachea,  416. 

tubular,  360,  370. 

Tyson's,  454. 

of  uterus,  467. 

of  Vesalius  (bronchial),  625. 


Glandula  socia  parotidis,  341. 
Glans  clitoridis,  471. 

penis,  460. 

corona  of,  460. 

— -  structure  of,  461. 

Glasserian  fissure,  43. 
Globuli  Arantii,  486. 
Globus  major,  451. 

minor,  451. 

Glomeruli,  437. 

GJoMo-epiglottid  folds  or  ligaments,  430. 

pharyngeal  nerve.     See  Nerve. 

Glenoid  cavities  in  general,  11. 

ligaments.    See  Ligaments. 

Glottis,  430. 

differences  in  size  of,  435, 

Gomphosis,  114. 
Groove,  basilar,  34. 

bicipital,  78. 

cuboid,  100. 

dental  primitive,  184. 

■  secondary,  184. 


■  digastric,  43,  47. 

-  ethmoidal,  40. 

-  inferior  petrosal,  49. 

-  lachrymo-nasal,  51. 

■  longitudinal,  of  cranium,  47 

■  mylo-hyoidean,  50. 
•  obturator,  88. 

-  optic,  37. 

■  sub-pubic,  88. 


Heart,  479. 

auricles  of,  external  surface,  482. 

interior  of,  486. 

muscular  fibres  of,  490L 

musculi  pectinati,  404. 

orifices  of,  484. 


'  auriculae  of,  482. 

—  interior  of,  487. 


•  bone  in,  489. 

■  cellular  tissue,  493. 

■  chordae  tendineee,  483. 
-  columnae  cameae,  483. 

■  conformation  of,  external,  480. 
internal,  482. 


■  development  of,  492. 

■  fibrous  framework  of,  488. 
'  foramen  of  Botal,  486. 
ovale,  486. 

'  remains  of,  486. 


■  foramina  Thebesii,  487. 

-  fossa  ovalis,  486. 

-  function,  492. 

-  furrow,  auriculo-ventricular,  481. 

inter-auricalar,  482. 

ventricular,  anterior  and   port*- 

nor,  481. 
.  muscular  fibres  of,  488. 
structure  of,  488. 

■  nerves  of,  492. 

•  separation  of,  into  right  and  left  hearts,  490. 

■  septum,  inter-auricular,  482. 
ventricular,  481. 


•  serous  coat,  external,  487. 
internal,  487. 

sounds  of,  493. 

•  structure  of,  487. 

■  tubercle  of  Lower,  486, 

•  valve,  Eustachian,  486. 

mitral,  484, 

of  Thebesius,  486, 

tricuspid  or  Iriglochin,  484, 

■  valves  of,  auriculo-ventricular  left,  484, 

right,  485, 

— ^ semilunar.     See  Sigmoid. 

■  sigmoid,  aortic,  484. 

pulmonary,  484. 


ventricles  of,  external  surface,  480, 

interior  of,  483. 

muscular  fibres  of,  488. 

. musculi  papillares,  484. 

orifices  of,  483. 


vessels  of,  491. 

zones,  fibrous,  of,  488. 
Heel,  bone  of,  100. 
Helicotrema,  679. 
Helix,  and  its  furrow  or  groove,  666. 

cartilaginous  process  of,  667. 

Hemorrhoidal  arteries.     See  Arteries. 
nerves.     See  Nerves. 


Hepatic  artery,  in  the  liver,  394,  395. 


888 


INDEX. 


Hepatic  duct,  395. 

in  the  liver,  394,  395. 

Hiatus  Fallopii,  44. 

Hilus  of  spleen,  <fcc.     See  those  organs. 

Hip-joint,  1S9. 

ligaments  of,  160. 

Horizontal  plate  of  palate  bone,  53. 

Human  body,  general  view  of,  1-4. 

Humerus,  78. 

Humours  of  eye.     See  Eye. 

Hymen,  469. 

Hyoid  bone  or  apparatus,  109. 

■Hypo- glossal  nerve.     See  Ntne. 

/ieo-coscal  valve,  372. 

development  of,  384. 

structure  of,  373. 

uses  of,  373. 

colic  valve,  372. 

Ileum,  362. 

structure  of.    See  Intestine,  small. 

Iliac  arteries.     See  Arteries. 

flexure,  371. 

fossa,  external,  88. 

internal,  88. 

region,  352. 

veins.     See  Veins. 

/Ko-pectineal  eminence,  89. 
Ilium,  89. 

Impression,  deltoid,  78. 
Incisive  canal,  52. 

fissure,  53. 

Incisura  tragica,  666. 
Incus,  674. 

Indented  sutures,  115. 
/n/ra-orbital  canal,  51. 

foramen,  59. 

nerves.    See  Nerves. 

spinous  fossa,  76. 

Infundibula  of  kidneys,  439. 
Infundibulum  of  base  of  brain,  729. 

cochlea,  678. 

nasal  fossa,  41,  62. 

right  ventricle  of  heart,  481 

Inguinal  canal,  304. 

ring,  303. 

Insula  of  Reil,  745. 

Iniegumentum,  713  (note). 

/nier-articular  cartilages.    See  Cartilages. 

auricular  furrow,  482, 

septum,  482. 

columnar  fascia,  301. 

condyloid  notch,  95. 

costal  arteries.     See  Arteries. 

nerves.     See  Nerves, 

spaces,  71. 

lobular  fissures,  spaces,  and  vessels  of  liver,  301 

of  lungs,  414. 

osseous  arteries.     See  Arteries, 


cartilages,  112. 

ligaments.     See  Ligaments. 

muscles.     See  Muscles. 

•  nerves.     See  Nerves. 

spaces  of  hand,  84. 

foot,  106. 

•  peduncular  space,  711,  728. 
spinous  ligaments,  119. 

■  trochanteric  line,  94. 

•  ventricular  furrow,  480. 
septum,  480. 

•  vertebral  foramina,  20,  30. 
■  substance  or  disc,  115. 

ligaments,  115. 


Intestine,  laxge,  370. 

. coats  of,  378,  379. 

development  of,  383. 

divisions  of,  371. 

■ follicles  of,  379. 

functions  of,  382. 

lymphatic  glands  and  vewek,  379. 

structare  of,  378. 

tubuli  of,  379. 

vessels  and  nerves  of,  379, 

Intestine,  small,  361. 

coats  of,  366, 


convolutions  of,  364. 
crypts  of,  370. 
development  of,  383. 
divisions  of,  361. 
follicles  of,  agmiuated,  369. 


Intestine,  small,  follicles  of,  Lieberkuhn'a,  37ft>)i|N^- 

solitary,  369.  «^    ' 

functions  of,  370, 

glands  of,  366. 

■ lymphatic  glands  of,  624. 

lymphatics  of,  624. 

papillae  of,  367. 

• properly  so  called,  363. 

structure  of,  365. 

tubuli  of,  370. 

valves  of,  366. 

vessels  and  nerves  of,  370. 

villi  of,  367. 

Intestines  in  general,  361. 

development  of,  383. 


JnZra-lobular  veins  of  liver,  395  (note). 

spinal  veins.     See  Veins. 

Iris,  657. 

layers  of,  659. 

muscular  fibres  of,  658  (note). 

structure,  658.- 

uses  of,  659. 

vessels  and  nerves  of,  659. 

Ischiadic  notch,  89. 
Ischio  rectal  fossas,  308. 
Ischium,  89, 
Island  of  Reil,  745. 
Isthmus  faucium,  325. 

ovalis  (heart),  486. 

of  the  encephalon,  710. 

comparative  anatomy,  715. 

■ development  of,  715. 

divisions  of,  710. 

fasciculus  of,  triangular,  710-711. 

furrow,  lateral,  of,  710. 

internal  structure  of,  713. 

lower  stratum,  713, 


--  middle  stratum,  713. 
upper  stratum,  713. 


sections  of,  713, 

Iter  dentis,  188, 

Ivory  of  teeth.     See  Teeth. 

Jacob's  membrane,  660, 

structure  of,  661. 


Jaw,  lower,  57. 

articulations  of,  128, 


upper,  bones  of,  51, 

—  articulations  of,  126, 


Jejunum,  362. 

— ; structure  of.     See  Small  Intestme. 

Joints.     See  Articulations. 
Jugal  columns,  127. 

bone,  54. 

Jugular  eminence,  34. 

fossa,  43. 

veins.     See  Veins. 

internal,  sinus  of,  583. 

Kidneys,  436, 

-  acini,  438, 
--  adipose  capsule  of,  437 

-  calyces  of,  439, 

-  coat  of,  437. 

-  cortical  substance  of,  438. 

-  development  of,  440. 

-  functions  of,  440. 

-  glomeruli,  437. 

-  hilus  or  fissure,  436. 

-  papillae,  437. 
■-  pelvis  of,  440. 

-  pyramids  of,  Ferreim'a,  437, 
Malpighi's,  437. 


■  tubes  of,  convoluted,  437, 
'  straight,  437. 


tubular  portion,  438. 

—  structure  of,  438, 


•  vessels  and  nerves,  438, 


See  thoM 


Knee-joint,  arteries,  ligaments,  and  nerves, 
parts. 

Labia  pudendi,  470. 
Labyrinth,  ethmoidal,  40, 

fluids  of,  679. 

lining  membrane  of,  680. 

membranous,  679. 

osseous,  675.      See   Cochlea,  Semi-ciraikm 

Canals,  and  Vestibule. 

Lacerated,  foramen  anterior,  47. 

posterior,  44. 


IKDEX. 


Lacerated,  foramen  superior,  39. 
Lacerti  teretes  of  heart,  483. 
Lachrifmal  bone,  56. 

canals,  651. 

caruncula,  647. 

gland,  651. 

groove,  or  fossa,  36,  651. 

papills,  or  tubercles,  645. 

passages,  651. 

mucous  coat  of,  654. 


■  puncta,  652. 
sac,  653. 


Lachrymo-aasal  groove,  51. 

canal,  652. 

Lacteals,  611. 

of  intestines,  612. 

Lactiferous  ducts,  473. 
Lacuna  magna,  460  (note). 
Lacuna  of  urethra,  460. 
Lacus  lachrymalis,  647. 
Lambdoidal  suture,  46. 
Lamina  cinerea,  730. 

of  cornea,  745. 

cribrosa  of  ethmoid,  40. 

of  internal  auditory  meatus,  678,  680. 

gyrorum,  677. 

papyracea,  41. 

spiralis,  membranous  and  osseous,  677. 

Laryngeal  nerves.     See  Nerves. 
Larynx,  422. 

articulations  of,  426. 

cartilages  of,  423. 

ossification  of,  435. 


Ligaments  of  auricle,  intrinsic,  667. 

of  bladder,  anterior,  308,  440. 

■ posterior,  440,  475. 

broad,  of  liver,  386. 

uterus,  465. 

'  calcaneo-cuboid,  inferior,  173. 
internal,  173. 
superior.  172. 


•  scaphoid,  inferior,  172. 
superior,  172. 


of  canthus,  external,  647. 
capsular,  acromin-clavicular,  135. 

atlanto-axoid,  119. 

carpo- metacarpal  of  thumb,  150. 

■of  little  finger,  ISO. 


hip-joint,  160. 
knee-joint,  166. 
occipito-atlautoid,  118. 
axoid,  119. 


-  development  of,  435 

•  functions  of,  435. 

•  glottis,  430. 

•  m  general,  429. 

•  ligaments  of,  425. 

•  mucous  membrane  and  glands  of,  475. 

•  muscles  of,  427. 
'  sinus  of,  434. 

'  surface,  external,  429. 
internal,  430. 


■  ventricle  of,  427. 

'  vessels  and  nerves,  435. 


Leg,  articulations  of,  168. 

bones  of,  96. 

compared  with  forearm,  105. 

fascia  of,  311. 

Lemniscus,  711. 

Lens.     See  Crystalline  Lens. 
Levator  muscles.     See  Muscles. 
Levers,  three  orders  of,  in  body,  199. 
Ligamenta-lsXs.  of  uterus,  475. 

subflava,  general  characters,  112. 

of  vertebral  column,  115. 

Ligaments  in  general,  1 13. 

articular,  112. 

capsular,  1 12. 

interosseous,  112. 

membranous,  112. 

structure  of,  174. 

yellow  or  elastic,  112. 

Idgaments  in  particular,  113. 

accessory,  of  shoulder-joint,  139. 

hip-joint,  160. 

knee-joint,  165. 

•  Weitbrecht,  144. 


'  alar,  of  axis  (or  odontoid),  119. 

of  knee,  165. 

'  of  ankle-joint,  lateral,  anterior  external,  1 69. 

external  proper,  169. 

internal,  169. 

posterior,  169. 


annular,  of  radius,  142, 

atlas,  117. 

carpus,  anterior,  318, 

dorsal,  318. 


tarsus,  dorsal  and  lateral,  313. 

arjrteno-epiglottid,  426. 
astragalo-calcaneal,  interosseous,  171. 
•  external,  171. 


posterior,  171. 

scaphoid,  superior,  172. 


atlanto-axoid,  anterior,  117. 
■  posterior,  117. 
capsular,  117. 


odontoid,  transverse  or  annular,  117, 
crucial,  117. 


scapulo-humeral,  137. 

sterno-clavicular,  136. 

■  of  each  row  of  carpal  bones,  147. 

-  two  rows  of  carpal  bones,  147. 
carpo-metacarpal,  dorsal,  150. 

palmar,  150. 

interosseous,  with  os  mag 

num,  150. 
of  little  finger,  150. 

thumb,  150. 

cervical,  posterior,  of  quadrupeds,  117. 
check,  of  axis  (or  odontoid),  119. 
chondro-sterual,  anterior,  131. 

interosseous,  131. 

posterior,  131. 

■  superior  and  inferior,  131 


'  xiphoid,  131. 


ciliary,  656. 

conoid,  135. 

coraco-acromial.  140. 

clavicular,  anterior,  or  trape7oid,  136 

posterior,  or  conoid.  136 

coraco-humeral,  139. 


—  coracoid,  139. 

—  costo-clavicular,  138. 
coracoid,  1 39. 

■  transverse,  interosseous,  131 
posterior,  131. 


—  superior,  131. 


■vertebral,  anterior,  131. 

inferior,  131. 

interosseous,  131. 

stellate,  131. 

superior,  131. 


cotyloid,  of  hip-joint,  159. 


crico-arytenoid,  426. 

thyroid,  middle  and  lateral,  436 


crucial,  of  atlas,  117. 

knee-joint,  164. 


of  cuneiform  bones  of  tarsus,  170. 

and  scaphoid,  171 


third  and  cuboid,  l7l 

deltoid,  169. 

dorsal,  annular,  of  carpus,  318. 
■  tarsus,  313. 


carpo-metacarpal,  149. 

•  of  carpus,  149. 

—  metacarpus,  149. 

—  metatarsus,  175. 

■  tarso-metatarsal,  175. 

•  of  tarsus,  171. 


elbow-joint,  external  lateral,  141. 

internal  lateral,  141. 

anterior,  141. 

■  posterior,  142. 


falciform,  303 
Fallopius's,  302 
of  Ferr^in,  427. 
Gimbernat's,  303. 
glenoid,  carpal  anterior,  148. 
■  posterior,  148 


metacarpo-phalangal,  152. 
metatarso-phalangal,  175. 
phalangal,  of  fingers,  153. 
toes,  176. 


scapulo-humeral,  138. 


of  auricle,  anterior  and  posterior,  667. 


5U 


glosso-epiglottid,  425. 

of  hip-joint,  anterior  superior,  160. 

— accessory.  160. 

cotyloid,  160. 

iuter-articular,  161. 


890 


Ligaments  of  hip-joint,  round,  161. 

capsular,  160. 

—  I  of  humero-cubital,  141. 

hyo-epiglottid,  425. 

ilio-lurabar,  156. 

inter-articular,  acroinio-claTicular,  135. 

of  hip-joint,  160. 

of  shoulder-joint,  137. 

sterno-clavicular,  136. 

temporo-maxillary,  128. 

of  wrist,  143. 


osseous,  astragalo-calcaneal,  171. 

of  carpal  bones,  147. 

carpo-metacarpal,  149. 

costo- transverse,  131. 

vertebral,  131. 


of  forearm,  144. 

—  knee-joint,  164. 

—  leg,  169. 

—  OS  magnum  and  metacar- 

pus, 149. 

■  metacarpal,  149. 

■  metatarsal,  175. 
peroneo-tibial,  168. 
pubic,  156. 
radio-cubital,  143. 
sacro-iliac,  155. 
tarsal,  of  first  row,  171. 

■  second  row,  171. 


tarso-metatarsal,  175. 

vertebral,  115. 

clavicular,  137. 

spinous,  116. 

vertebral,  115. 

of  knee-joint,  163. 

accessory,  166. 

adipose  (so  called),  166. 

alar,  166. 

anterior,  163. 

capsular,  163. 

crucial  anterior,  164. 

•  posterior,  163. 


■  inter-articular,  163. 

osseous,  164. 

lateral,  external,  163. 
internal,  163. 


■  mucous  (so  called),  166. 
•  posterior,  163. 
transverse,  163. 


of  laryni,  425. 
—  malleus,  673. 

metacarpo-phalangal,  glenoid,  152. 

lateral,  152. 

■of  thumb,  152. 


of  metacarpus,  148. 
metatarso-phalangal,  glenoid,  176. 
—  lateral,  176. 


of  metatarsus,  175. 

occipito-atlantal  anterior,  superficial,  116. 

deep,  116. 

capsular,  117. 

lateral,  117. 

posterior,  116. 


'  axoid,  lateral,  120. 
middle,  120. 


odontoid,  lateral,  120. 
middle,  120. 

orbicular,    of   acromio-clavicular   articula- 
tion, 137. 

■ of  hip-joint,  158. 

scapulo-humeral,  139. 

sterno-clavicular,  137. 

palmar  of  carpo-metacarpal  joints,  149. 

carpus,  147. 

-  metacarpus,  148. 


of  patella,  164. 


perineal,  307. 

peroneo-tarsal,  anterior  external,  170. 

external,  170. 

posterior,  170. 


—  of  peroneo-tibial  articulations,  167,  168. 

—  perpendicular,  170. 

—  phalangal  of  fingers,  glenoid,  153. 
■  lateral,  153. 


toes,  glenoid,  177. 
lateral,  177. 


of  pisiform  and  cuneiform  bones,  147. 

plantar  inferior,  174. 

of  metatarsus,  176. 

tarso-metatarsal,  176. 


Ligaments,  plantar  of  tarsus,  172 

Poupart's,  302. 

proper,  of  scapula,  anterior,  140. 

posterior,  140. 


-  pterygo-maxillary,  235. 

-  pubic  anterior,  155. 

inferior,  155. 

interosseous,  155. 

posterior,  155. 

superior,  155. 

triangular,  155. 

■  radiated  chondro-sternal,  133. 

■  of  radio-carpal  articulation,  145. 
cubital  articulations,  144. 

■  recto-uterine,  467. 

■  round,  of  forearm,  144. 
hip-joint,  161. 

■  uterus,  466. 


■  sacro-coccygeal,  anterior,  120. 
posterior,  120. 


■  iliac,  anterior,  154. 

interosseous,  154. 

posterior  vertical,  155. 

superior,  154. 

sciatic,  great,  155. 

small,  155. 


vertebral,  120. 


—  scaphoid  and  cuboid,  172. 

—  of  shoulder-joint,  136. 

—  spheno-maxillary,  129. 

—  stellate,  costo-vertebral,  130. 
'  or  radiated,  chondro-stemal,  13L 


•  stylo-maxillary,  129. 
mylo-hyoid,  129. 

■  sub-pubic,  or  inferior  pubic,  156. 

•  supra-spinous,  119. 

■  suspensory  of  clitoris,  471. 
'  penis,  456. 


—  liver,  386,  475. 

—  of  first  row  of  tarsal  bones,  171 . 
second  row  of  tarsal  bones,  171. 

—  tarso-metatarsal,  dorsal,  174. 

interosseous,  174. 

oblique  of  fifth  toe,  175. 

plantar,  174. 

—  of  temporo-maxillary  articulation,  lateral 

external,  128. 

—  internal,  129. 

—  thyro-arytenoid,  or  chords  vocales,  427. 
epig:lottid,  425. 

hyoid,  middle  and  lateral,  425. 

—  tibio-tarsal,  anterior,  169. 
internal,  169. 

posterior,  169. 


■  of  tragus,  667. 

•  transverse  of  atlas,  117. 

knee,  163. 

metacarpus,  149. 

•  trapezoid,  136. 

■  triangular  of  perinaeum,  307. 

penis,  455. 

symphysis  pubis,  156. 

urethra,  307. 

wrist,  143. 


■  of  two  rows  of  tarsal  bones,  171. 

■  vertebral,  anterior  common,  116. 
interosseous,  116. 

•  posterior,  116. 


—  yellow  elastic,  117. 


-  vesico-uterine,  467. 

-  of  Weitbrecht,  144. 

—  Winslow,  164. 

—  wrist-joint,  external  anterior,  146. 

—  internal  anterior,  146. 

middle  anterior,  146. 

■ external  lateral,  146. 

. internal  lateral,  146. 

posterior,  146. 


of  Zinn,  650. 


Ligamentum  arcuatum  of  diaphragm,  213 

denticulatum,  694. 

fibulae  anterius,  170. 

medium,  170. 

perpendiculare,  170. 

posterius,  170. 

gastro-phrenicum,  354. 

latum  pulmonis,  413. 

longum  plantae,  173. 

mucosum  of  knee-joint,  164. 

nnchffi,  202. 


INDEX. 


891 


Ligamentum-piteXIs,  164. 

phrenico-lienale,  403. 

proprium  anterius  scapuls,  140. 

posterius  scapula,  140. 

teres  of  forearm,  144. 

■  '■  hip-joint,  161. 

lambs.    See  Extremities. 

Limbus  luteus,  660. 

Line,  inter-trochanteric,  94. 

mylo-hyoidean,  57. 

naso-labial,  327. 

Lines,  semicircular  of  occipital  bone,  S3> 

-— ^— — ^— OS  cuxse,  88. 

Litua  alba,  301. 

cervical,  300. 

aspera,  94. 

Ups,  325. 

— —  development  of,  326. 

movemeuts  of,  238 

muscles  of,  326. 

structure  of,  326. 

uses  of,  327. 

vessels  of,  327. 

Liquor  Cotunni,  680. 

• Morgagni,  663. 

of  Scarpa,  680. 

Liver,  385. 

acini  of,  390. 

circumference  of,  389. 

•  coats  of,  390. 

colour  and  fragility,  389. 

development  of,  399. 

ducts  of,  391  (notes). 

excretory  apparatus  of,  395. 

figure,  386. 

fissures,  387. 

functions,  400. 

groove  for  vena  cava,  389 

hilusof,  388. 

ligament,  broad  or  suspensory,  386. 

coronary,  390. 

falciform,  386. 

triangular,  left  and  right,  390 

lobes,  387. 

lobules  or  granules,  388. 

arrangement  of,  391. 

'  structure  of,  394  (note). 


-  lymphatics  of,  393. 
-nerves  of,  393. 
-porta  of,  388. 

-  proper  tissue,  390  (note). 

■  situation,  385. 

■  size,  385. 
-structure  of,  390. 

-  surface,  inferior  or  plane,  386. 
•  superior,  386. 


Lungs,  vessels  and  nerves  of,  421. 

weight  of,  absolute  and  specific,  410. 

Lymphatic  duct,  right,  619. 

-  glands  in  general,  616. 

preparation  of,  617. 

structure  of,  617. 

in  particular,  619. 

axillary,  628. 

bronchial,  625. 

cervical,  deep,  628. 

superficial,  627. 


■  of  cranium,  626. 

•  duodenal,  624. 

■  of  face,  626. 

■  ileo-colic,  624. 

•  iliac,  external,  622. 

internal,  622. 

■inguinal,  619. 

■  intercostal,  625. 

■  of  intestine,  great,  624. 
—  small,  624. 


of  liver,  623. 

of  lower  extremity,  620. 

lumbar,  621. 

mammary,  625. 

mediastinal,  625. 

mesenteric,  625. 

meso-colic,  624. 

of  pancreas,  624. 

parotid,  627. 

of  pelvis,  621. 

popliteal,  619. 

pulmonary,  625. 

sacral,  621. 

of  spleen,  624. 

of  stomach,  624. 

.sub-maxillary,  627. 

sub-sternal,  625. 

tibial  anterior,  619. 

tracheal,  627. 

of  upper  extremity,  628. 

■ part  of  trunk,  628. 

■  hearts  of  lovfcr  animals,  617. 

'  networks,  superficial  and  deep,  613. 

■  plexuses,  612. 
system,  611. 


vessels  of,  392. 

arrangement  of,  393. 

Lobes  and  lobules  of  organs.     See  thorn  organs. 
Lobule  of  ear,  666. 
Lobulus  caudatus,  389. 

quadratus,  389. 

SpigeUi,  389. 

Locus  niger,  751. 

perforatus  anterior,  731. 

middle  or  posterior,  727. 

Longissimus  dorsi.     See  Muscles. 

Longitudinal  fissures  of  liver,  &c.    See  those  organs. 

vein  of  spine.     See  Vein*. 

Luette  of  bladder,  459. 
Lumbar  nerves.     See  Nerves. 

region  of  abdomen,  352. 

veins.     See  Veins. 

vertebne.     See  Vertebra  and  Vertebra. 

Lungs,  409. 

air-ceUs  of,  415. 

air-tubos  of,  416. 

cellular  tissue  of,  inter-lobular,  415. 

development  of,  421. 

external  conformation  of,  411. 

^,  fissures  of,  inter-lobular,  411. 

foetal,  421. 

functions,  422. 

lobes  of,  411. 

lobules  of,  415. 

structure  of,  419. 

lymphatic  system  of,  421. 

root  of,  412. 

size  of,  409. 

■ structure  of,  413. 


vessels  in  general,  611. 

aflferent,  614. 

'  anastomoses  of,  614. 

branches  of,  614. 

coat  of  external,  616. 

'  internal,  616. 


course  and  direction,  614. 
'  deep  and  superficial  sets  of,  618. 
■  efferent,  614. 

origin  of,  in  different  tissues,  612. 
•  preparation  of,  617. 

structure  of,  616. 

terminations  of,  614. 

valves  of,  617. 

vessels  of,  616. 

in  particular,  618. 

of  bones,  16. 

of  brain,  628. 

of  cellular  tissue,  613. 

cervical,  628. 

'  posterior,  639. 


of  cranium,  637. 

dorsal,  629. 

of  dura  mater,  627. 

epigastric,  622. 

of  external  genitals,  male  and  &• 

male,  620. 
of  face,  627. 
gluteal,  620. 
of  heart,  626. 
ilio-lumbar,  622. 
intercostal,  626. 
of  intestines,  great,  625. 
■  small,  625. 


of  kidneys,  622. 

of  lining  membrane  of  bloodvessels, 

613. 
of  liver,  deep,  623. 

superficial,  623. 


'  of  lower  extremity,  deep  and  super* 
ficial,  619. 
lumbar,  lateral,  622. 

■  superficial,  620. 


of  lungs,  deep  and  superficial,  626. 


892 


INSEJX. 


Lymphatic  vessels,  mammary,  internal,  626. 

meningeal,  627. 

of  mucous  membranes,  612. 

occipital,  627. 

of  pelvis,  621. 

pericardiac,  626. 

periuaeal,  620. 

peroneal,  620. 

of  serous  and  sysovial  tissues,  613, 

of  skin,  613. 

of  spleen,  624. 

of  stomach,  624. 

sub-sternal,  626 

supra-renal,  622, 

temporal,  626. 

of  testicles,  622. 

thorax,  625. 

thymic,  626. 

thyroid,  627. 

tibial,  anterior  and  posterior,  620. 

of  upper  extremity,  628. 

•  part  of  trunk,  628. 


uterine  628. 


Lyra,  738. 

Macula  cribrosa,  676l 
Malar  foramina,  54. 

process,  51. 

bone,  54. 

Malleolus,  external,  97. 

internal,  98. 

Malleus,  and  ligament  of,  673. 

muscles  of,  673. 

Mamma,  471. 

adipose  tissue  of,  473. 

development  of,  474. 

fibrous  tissue  of,  473. 

glandular  tissue  of,  473. 

lactiferous  ducts  of,  473. 

■  of  the  male,  473. 


vessels  and  nerves  of,  474. 

Mammary  gland.     See  Mamma. 
Mammillm.     See  Nipples. 
Mammillary  enlargements  of  posterior  median  colunms 
of  spinal  cord,  704. 

of  inferior  vermis,  716,  718. 

tubercles,  426. 

Manubrium  of  malleus,  673. 

of  sternum,  65. 

Marrow  of  bones,  12. 

Massa  camea  Jacobi  Sylvij,  291. 

Mastoid  foramen,  43. 

portion  of  temporal  bone,  43. 

process,  43. 

Maxillary  arteries.     See  Arteries. 

bone,  inferior,  57. 

superior,  51. 

canal,  superior,  51. 

inferior,  58. 

nerves.     See  Nervet. 


tuberosity,  51. 

Jlfar^o-dentatus,  660. 
MeeUus  of  nose,  inferior,  54. 

middle,  41. 

•  superior,  41. 

auditorius  externus,  44. 

iutemus,  44. 

urinarius,  female,  471. 

male,  461. 


See  Bar. 
See  Ear. 


Mechanism  of  particular  joints. 
Mediastinum,  anterior,  414. 
posterior,  413. 


See  those  joints. 


Medulla  oblongata,  702. 


comparative  anatomy  of,  709. 

development  of,  708. 

external  conformation  of,  702. 

anterior  surface,  703. 

lateral  surfaces,  704. 

—  posterior  surface,  704. 


'  faisccaux  innomines  of,  706. 

at  base  of  brain,  706. 

•  in  isthmus,  715. 


fasciculi  graciles,  708  (note). 

olivary,  708  (note). 

re-enforcing,  708. 

teretes,  708  (note). 

•  pyramidal,  702,  704, ' 

fibres  of,  antero-posterior,  707. 

arched,  704. 

decussation  of,  706. 


MeduUa  oblongata,  foramen  caecum  of,  703. 

furrow  of  median,  anterior,  703. 

posterior,  704. 

■  internal  structure  of,  706. 


—  neck  of,  702. 

sections  of,  705. 

of  long  bones,  12. 

spinalis.     See  Spinal  Cord. 


examined  by  hardening,  706. 

sections,  705. 

water,  706. 


Medullary  canal  of  long  bones,  13. 
membrane,  14. 


Meibomian  glands,  648. 
Membrana  nictitans,  648. 

pupillaris,  659. 

Ruyschiana,  657. 

sacciformis,  143. 

tympani,  669. 

secundaria,  670. 


uvea,  659. 


Membrane,  hyaloid,  661. 

obturator,  or  sub-pubic,  155. 

Membranes  of  cerebro-spinal  axis.     See  ATodmotd, 
Dura  Mater,  and  Pia  Mater. 

of  eye.     See  Eye. 

fibro-mucous       See    Tibro-mucous    Mem- 

branes. 

—  fibro-serous.    See  Fibro-serous  Membranes 

— — — ^  mucous.     See  Mucous  Membranes. 
— ^^^—  serous.     See  Serous  Membranes. 
^— — ^—  synovial.     See  Synovial  Membranes. 
Membranous  labyrinth,  679, 

part  of  urethra,  458. 

Meningeal  arteries.    See  Arteries. 
Meninges,  681. 
Meningoses,  113. 
Meniscus,  113. 
Mental  fossa,  57. 

foramen,  57. 

process,  56. 

Mesentery,  364,  477. 

left  layer,  475. 

right  layer,  475. 


Meso-cxcxim,  471. 
■   colon,  iliac,  475. 

left  and  right,  475. 

transverse,  375. 

layer,  inferior,  476. 

—  superior,  477 


'  ■    -  ga-strium,  478. 
— —  rectum,  475. 
Metacarpus,  bones  of,  84. 

■ differential  characters,  89. 

general  characters,  85. 


■  compared  with  metatarsus,  109. 


Metatarsus,  bones  of,  103. 

characters,  general,  103. 

differential,  102. 


compared  with  metacarpus,  109. 

Milk  teeth.     See  Teeth. 

Modiolus  of  cochlea,  678. 

Mom  Veneris,  470. 

Morsus  diaboli,  and  fimbriie  of  Fallopian  tube,  463. 

Motores  oculi  nerves.    See  Nerves. 

Mouth,  component  parts  of,  422. 

situation,  dimensions,  &c.,  422. 
Movements  of  joints.     See  Articulations. 
in  general,  148. 


lips  and  face,  238. 


Mucous  bursae  (so  called),  175. 

membranes,  in  general,  421. 

chemical  composition,  42L 

epithelium,  421. 

■  of  particular  organs.     See  thoa 

organs. 
—  structure,  421. 


Mucro,  65. 
MultifiduM  spinae.     See  Muscles- 
Muscles  in  general,  190. 

action  of,  194. 

angle  of  incidence  on  bones,  195. 

antagonist,  196. 

aponeuroses  of,  193. 

arrangement,  physiological,  of,  291. 

attachments  of,  192. 

— fixed,  191 

movable,  193. 


broad,  190. 
conge.nen<ns.  197. 


IKDEX. 


Miuehs,  direction  of,  191. 

'  figure  of,  191. 

insertion  of,  into  other  puts,  19t. 

long,  191. 

momeutum  of,  195. 

nerves  of,  763. 

nomenclature  of,  190. 

number  of,  190. 

orde'  of  description  of,  197. 

origin  and  termination  of,  198. 

preparation  of,  197. 

relations  of,  to  other  ports,  101 

satellite,  192. 

sheaths  for,  296. 

short,  191. 

structure  of,  193. 

tendons  of,  193. 

uses  of,  194. 

volume  of,  190. 

in  particular,  196-291. 

——^—  of  particular  organs,  parts,  or  regions, 
those  organs,  parts,  or  regions. 
'  abductor  brevis  pollicis,  260. 

digiti  minimi,  262. 

pedis,  289. 


See 


'  indicia,  264. 

'  longus  pollicis,  258. 

•  oculi,  650. 

■  pollicis,  287. 

—  pedis,  277. 


•  accelerator  urinse,  456. 
'  accessorious  pedis,  280. 

ad  sacro-lumbalem,  877. 


•  adductor  brevis  femoris,  276. 

digiti  minimi  (opponens),  281. 

longus  femoris,  276. 

magnus  femoris,  276. 

oculi,  650. 

pollicis  manOs,  288. 

pedis,  288. 


anconeus,  258. 

anterior  auriculs,  230. 

antitragieus,  667. 

articulo-spinalis,  201. 

arytenoideus,  429. 

obliquus,  429. 

transversus,  430. 


•  aryteno-epiglottideus,  430. 
'  attoUens  auriculam.  231. 
•  oculum,  650. 


—  attrahens  auriculam,  231. 

—  auricularis  anterior,  231. 
posterior,  231. 

--  superior,  231. 


•  azygos  uvulie,  332. 
'  basio-glossus,  338. 


biceps  cruris  vel  femoris,  ! 

flexor  cubiti,  245. 


—  biventer  cervicis,  201. 

—  brachialis  anticus,  246. 

—  buccinator,  235. 

—  bulbo-cavernosus,  456. 

—  caninus,  236. 

—  cerato-glossus,  338. 

—  chondro-glossus,  338. 

—  ciliaris,  232. 

—  circumflexus  palati,  332. 

—  coccygeus,  381. 

—  complexus,  205. 
minor,  205. 

—  compressor  narium,  233. 
nrethrffi,  460. 

in  the  female,  470. 


—  vente  dorsalis  penis,  460. 


-  constrictor  inferior,  346. 

iiiedius,  347. 

superior,  347. 

—  vagince,  469. 


—  coraco-brachialis,  246. 

—  coTrngator  supercilii,  232. 

—  cremaster,  210,450. 

—  crico-arytenoideus  lateralis,  428. 

posticus,  428. 

CBsophageus,  352. 

thyroideus,  421. 

—  crotaphyte,  S40. 

—  crureus,  273. 

—  cutanei,  294. 

—  deltoideus,  241. 

—  depresssor  alae  nasi,  334. 


Muscles,  depressor  angali  oris,  837. 

labii  inferioris,  237. 

superioris  alsque  nasi,  234. 


oculi,  650. 
urethrjE  (Santorini),  460. 
in  the  female,  470. 


diaphragma,  218. 

digastricus,  228. 

elevatores  nrethno  (Santorini),  400. 

erector  clitoridis,  471. 

penis,  456. 

spinee,  202. 

extensor  brevis  digitorum  pedis,  286. 

pollicis,  259. 

carpi  radialis  brevior,  255. 

longior,  355. 


'  ulnaris,  258. 


—  communis  digitorum,  866. 

—  digiti  minimi,  257. 

—  indicis,  259. 

—  longus  digitorum  pedis,  278. 
pollicis,  259. 

—  ossis  metncarpi  pollicis,  258. 

—  primi  internodii  pollicis,  258. 

—  proprius  auricularis,  256. 
indicis,  259. 

—  pollicis  pedis,  279. 


secundi  internodii  pollicis,  958. 


flexor  accessorius,  290. 

brevis  digiti  minimi,  262. 

minimi  pedis,  289. 


digitorum  pedis,  389 
pollicis,  262. 

■  pedis,  287. 


carpi  radialis,  850. 
ulnaris,  250. 

longus  digitorum  pedis,  335. 

pollicis,  253. 

pedis,  886. 

perforans,  251. 

'  pedis,  285. 


perforatus,  252. 

pedis,  390. 


profundus  digitorum,  252. 

sublimis  digitorum  331. 

frontalis,  230. 

gastrocnemius,  281. 
•  gemellus  inferior,  267. 
superior,  267. 

genio-hyoglossus,  338. 
hyoideus,  229. 

glosso-staphylinus,  332. 

glutseus  niaximus,  264. 

medius,  265. 

minimus,  266. 


gracilis,  275. 

helicis  major,  667. 
minor,  667. 

Homer's,  653. 

Houston's,  457. 

hyo-glossus,  338. 

iliacus,  215. 

indicator,  260. 

infra-costales,  232. 
spinatus,  243. 

intcr-costales  externi,  222. 
intemi,  222. 


■  ossei  manAs,  263. 

dorsales,  264. 

'  palmares,  264. 


■  pedis  dorsales,  290. 
plantares,  290. 


■  spinales  colli,  286. 

■  transversales  colli,  917. 
—  lumborum,  218 


ischio-bulbosus,  457. 

in  the  female,  470. 


cavernosus,  456. 

in  the  female,  471. 


coccygeus,  380. 


latissimus  dorsi,  198. 
laxatOT  tympani,  675. 
levator  anguli  oris,  236. 

scapulae,  201. 


ani,  380. 

labii  inferioris,  237. 

superioris,  236. 

alasque  nasi,  333 


menti,  237. 
oculi,  640. 


894 


INDEX. 


Muscles,  levator  palati,  332. 

palpebrae  superioris,  233,  648. 

— — — —  prostatae,  382. 

UTulte,  337. 

levatores  costarum  breviores,  222. 

—  longiores,  222. 


Muscles,  rectus  oculi  superior,  649. 
retrahens  auriculam,  230. 
rhomboideus  major,  200. 
minor,  200. 


lingualis  (Albinus  and  Douglas),  337. 

inferior,  337. 

superficialis,  337. 


-  longissimus  dorsi  in  tie  loins,  208. 

1 neck,  203. 

•  thorax,  203 


-longus  colli,  218 
-  lambricales  manOs,  253. 
•  pedis,  290 


accessory  fibres  to,  203,  204. 


-  mallei  externus  magnus,  673. 
parvus,  673. 


intemus,  674. 


-  masseter,  239. 

-  multifidus  spins  in  the  loins,  202,  (note). 
__ back,  203. 

■  neck,  204. 


-mylo-hyoideus,  229. 
-mjrrtiformis,  234. 

-  naso-labialis,  234. 

-  obliquus  abdominis  extemus,  208. 
■  intemus,  209. 


-  capitis  inferior,  206. 
superior,  206. 

-  oculi  inferior,  651. 
superior,  651. 


-  obturator  extemus,  268. 
■  intemus,  267 


occipitalis,  230. 
occipito-frontalis,  230. 

pharyngeus,  338. 


-  omo-hyoideus,  226. 

-  opponens  digiti  minimi,  262. 
—  poUicis,  260. 


-  orbicularis  oris,  235. 

'  palpebrarum,  231. 


-  palato-glossus,  332. 

pharyngeus,  332. 

staphylinus,  332. 

-palmaris  brevis,  261. 
longus,  250. 


-  palpebralis,  231. 

-  patheticus,  651. 
-pectineus,  275. 


-■ —  pectoralis  major,  220. 
minor,  221. 


perforatus  Casserii,  253. 
peri-staphylinus  extemus,  332. 
intemus,  332. 


peroneus  brevis,  280. 

longus,  280. 

tertius,  vel  anticus,  279. 


petro-pharyngeus,  348. 
pharyngo-staphylinus,  332. 
plantaris,  282. 
platysma  myoides,  224. 
popliteus,  283. 
pronator  quadratus,  253. 

radii  teres,  249. 

rotundas,  249. 


psoas-iliacus,  214 

magnus,  215 

parvus,  216. 


pterygoideus  extemus,  241 
internus,  240. 


pterygo-pharyngeus,  347. 
pubio-urethralis,  457. 
pyramidalis  abdominis,  212. 
nasi,  233. 


-  pyriformis,  266. 

-  quadratus  femoris,  268. 
-  lumborum,  216, 


—  meuti,  237. 


-  rectus  abdominis,  210 

capitis  anticus  major,  218. 

-  minor,  218. 


lateralis,  217. 
posticus  major,  206. 
minor,  206. 


•  femoris,  270. 

intemus,  272. 


•  oculi  extemus,  650. 

internus,  650. 

inferior,  650. 


-risorius  Santorini,  284. 

-  sacro-lumbalis,  in  the  loins,  203. 

in  the  thorax,  204. 

on  the  chest,  204. 


-  salpingo-pharyngeus,  338. 
■sartorius,  272. 

-  scalenus  anticus,  217. 

posticus,  218. 

-scalptor  ani,  275. 


scapulo-hyoideus,  226. 

semi-spinalis  colli,  204  (note). 

dorsi,  204  (note). 


■  membranosus,  270. 
'  tendinosus,  270. 


-  serratus  anticus,  223. 

-  parvus,  223. 


■  magnus,  221. 
-  posticus  inferior,  201 . 
■  superior,  201. 


•  soleus,  282. 
-  spheno-pharyngeus,  338. 
■  sphincter  ani  extemus,  380. 
■  intemus,  380. 


(esophagi,  350. 
vaginse,  470. 
vesicae,  442. 


-spinales  posteriores,  201. 

■ action  of,  203. 

'         general  view  of,  203. 

in  the  loins,  201. 

neck,  204. 

'  thorax,  204. 


■  spinalis  dorsi,  204. 

•  cervicis,  204. 


-  splenius  capitis,  202. 
-colli,  202. 


■stapedius,  671. 

■  sterno-cleido-mastoideus,  224. 

hyoideus,  226. 

thyroideus,  227. 

-  stylo-glossus,  337. 

hyoideus,  229. 

alter,  230. 


pharyngeus,  346. 


-  sub-clavius,  221. 
scapularis,  244. 

-  super-ciliaris,  232. 

■  supinator  radii  brevis,  256. 
longus,  254. 

-  supra-costales,  221. 

spinatus,  243. 

-suralis,  281. 

-  temporalis,  239. 

-  tensor  palati,  332. 

tarsi,  or  Homer's,  653. 

tympani,  671. 

vagina;  femoris,  271. 

-  tensors  of  fasciae,  296. 

-  teres  major,  198. 
minor,  243. 

-  thyro-arytenoideus,  428. 

epiglottideus,  428. 

hyoideus,  227. 

-  tibialis  anticus,  278. 
-  posticus,  284. 


•  trachelo-mastoideus,  204. 
■tragicus,  667. 

■  transversalis  abdominis,  210. 
-cervicis,  205. 


—  colli,  204. 
-  nasi,  234. 


■  transverso-spinalis,  202. 

— in  the  loins,  202. 

in  the  neck,  204. 

in  the  thorax,  204 


transversus  auriculae,  667. 

nasi,  234. 

pedis,  290. 

perinaei,  381. 

■  alter,  457. 


'  pollicis  pedis,  290. 


-trapezius,  198. 

-  triangularis  nasi,  234. 

oris,  237. 

stemi, 


-  triceps  adductor  femoria^  274. 


INDEX. 


Muscles,  triceps  extensor  cruris,  273. 

cubiti,  247. 

femoralis,  272. 

-  femoris  (auctor),  272. 


suralis,  281. 

-  trochlearis,  651. 

-  of  the  ureters,  445. 


vastus  externus,  273. 

intemus,  273. 


Nerves,  sensory,  common,  759,  7fl8. 

—  special,  762. 

spinal,  759. 

structure  of,  766. 

symmetrical,  760. 

sympathetic,  762,  764. 

structure  of,  767. 


•  Wilson's,  457. 

-  which  move  the  arm  upon  the  shoulder,  292. 

fingers,  293. 

foot  upon  the  leg,  293. 

forearm  upon  the  arm,  293. 

hand  upon  the  forearm,  293. 

leg  upon  the  thigh,  292. 

lower  jaw,  292. 

OS  hyoides,  292. 

pelvis,  292. 

radius  upon  the  ulna,  293. 

ribs,  292. 

: shoulder,  292. 

skin,  293. 

thigh  upon  the  pelvis,  292. 

toes,  293. 

■ vertebro-cranial  column,  292, 

—  walls  of  thorax  and  abdomen, 

292. 


•  zygomaticus  major,  236. 
■  minor,  236. 


Muscular  fibres,  filaments,  and  fasciculi,  198  (note). 
fibres  of  particular  organs.     See  those  organs, 

sheaths,  296. 

tissue,  involuntary,  198. 

structure,  322. 

voluntary,  198. 

— — ^ chemical  composition,  199. 

structure,  198. 


Musculi  pectinati,  486. 

papillares,  484. 

Musculo-cutaneoMs  nerves.    See  Nerves. 
Myology,  190. 

Nails,  636. 

lunule  of,  636. 

matrix,  636. 

structure  and  growth  of,  637. 

Nares,  anterior,  60. 

posterior,  60. 

Nasal  arteries.     See  Arteries. 
bone,  55. 

•■  cartilages.    See  Nose. 
duct  and  canal,  653. 

■-  eminence,  35. 

fossie,  62. 

meatuses,  41. 

nerves.     See  Nerves. 

process,  51. 

spine,  anterior  and  posterior,  82,  54. 

Nates  (of  brain),  712. 
Navicular  fossae.     See  Fossa. 
Necks  of  bones,  10. 

particular.    See  those  bones. 

Nerves  in  general,  759. 

anastomoses  of,  762. 

of  animal  life,  761. 

central  extremity  of,  760. 

classification  of,  759. 

course  of,  762. 

cranial,  759. 

different  kinds  of,  761. 

direction  of,  763. 

division  of  into  sets,  769. 

fibres  and  filaments  of,  767. 

'         ganglia  of,  765. 

connexions  of,  765. 

different  kinds  of,  765. 

structure  of,  768. 

ganglionic,  764. 

mode  of  division  of,  764. 

motor,  759. 

neurilemma  of,  766. 

of  organic  life,  761. 

origin  of,  apparent  and  real,  758. 

plexuses  of,  762.     See  Plexuses 

preparation  of,  769. 

relations  of,  763. 

respiratory,  760,  762. 

roots  of,  anterior  or  motor,  762. 

posterior  or  sensory,  762. 


termination  of,  764. 
in  particular,  769. 
abdominal,  great,  798. 

small,  799. 

abducens  oculi.    See  Motor  Oculi,  extemai. 
accessory,  of  internal  cutaneous,  785. 
saphenous,  801. 


'  obturator,  801  (note). 

'  spinal,  distribution  of,  849. 

function  of,  851. 

■  ganglion  of,  824. 


—  origin  of,  823. 

—  vertebral  course,  824. 


acromial,  778. 
alveolo-dental,  anterior,  834. 
posterior,  834. 


anal  cutaneous,  806. 

aortic,  sympathetic,  863. 

articular  of  ankle,  812. 

of  elbow,  785,  786. 

hip-joint,  800. 

of  knee,  anterior,  802. 

external,  808. 


of  wrist,  785. 

auditory.     See  Portio  Mollis. 
auricular,  anterior,  836. 
■  great,  778. 


•  internal,  812. 

•  from  obturator,  801. 

■  recurrent,  809. 

■  posterior,  or  azygos,  6U. 


of  pneumogastric,  845. 

■  posterior,  840. 


auriculo-occipital,  840. 
■  temporal,  836. 


axillary,  or  circumflex,  783. 
azygos,  of  knee-joint,  813. 
buccal,  835. 

of  facial,  841. 

bucco-labial,  835. 
bulbo-urethral,  806. 
calcaneal,  external,  812. 
'  internal,  813. 


cardiac,  great,  861. 

inferior,  left,  861. 

right,  861. 


lesser,  861. 

middle,  left,  862. 
right,  861. 

of  pneumogastric,  in  neck,  647. 

in  thorax,  837. 

•  of  recurrent  laryngeal,  837. 

—  superficial,  861. 

—  superior,  left,  861. 
-  right,  860. 


of  sympathetic,  860. 

carotid  branch  of  vidian,  833. 
of  sympathetic,  765. 

cerebral.    See  Cranial. 

cervical,  branches  of,  anterior,  776,  781. 
posterior,  773. 


■  number  of,  771. 
•roots  of,  771. 


cervical,  first,  anterior  branch  of,  776. 

posterior  branch  of,  773. 

second,  anterior  branch,  776. 

posterior  branch,  774. 


—  third,  anterior  branch,  777. 

posterior  branch,  774. 

—  fourth,  anterior  branch,  777. 
posterior  branch,  774. 

—  fifth  to  eighth,  anterior  branches,  781 

posterior  branches,  774 

-of  facial,  841. 

—  internal  descending,  780. 

—  superficial,  778. 


cervico-facial,  839,  841. 
chorda  tympani,  836. 

.  canal  for,  672. 


ciliary,  659,  830. 

nasal,  830. 

ophthalmic,  830. 

circumflex,  782. 


«96 

Nerves,  clavicular,  783.  "^''^    "  ^    .  W 

of  clitoris,  807. 

for  cochlea,  842. 

collateral  dorsal  of  fingers,  790. 

. of  thumb,  798. 

of  toes,  811. 

palmar  of  fingers,  788,  790. 

■  thumb,  788. 


rNDEX. 


•  comnmnicating  fibular,  811. 
tibial,  811. 

for  complexus,  773. 

for  coxo-femoral  articulation,  800  (note). 

cranial,  in  general,  816. 

central,  extremities  of,  817. 

classification  of,  816. 

distribution  of,  832. 

general  view  of,  853. 

nomenclature  of,  817. 

cranial,  in  particular,  832. 
first.     See  Olfactory. 

second.     See  Optic. 

third.     See  Motor  UcuH,  common. 

fourth.     See  Pathetic. 

fifth.     See  Trifacial. 

sixth.     See  Motor  Oculi,  external. 

seventh.     See  Portio  Dura  and  Pord'o 

Mollis. 

eighth.     See  Pneumogastric,  Glosso- 

pharyngeal, and  Spinal  Accessory. 

ninth.     See  Hypo-glossal. 

crural,  801. 

for  crureus,  802. 

cutaneous,  accessory  of  saphenous,  801 . 

— anal,  806. 

external,  of  arm,  785. 

'  of  musculo-spiral,  791. 

■of  thigh,  799. 


•  of  intercostal,  794. 
■  internal,  of  arm,  784. 

accessory  of,  785. 

of  musculo-spiral,  791. 

of  thigh,  801. 

■  of  Wrisberg,  785. 


■long,  of  obturator,  801  (note), 
-middle,  of  thigh,  801. 
•  of  musculo-cutaneous  of  arm,  785. 
■palmar,  787. 

■  perforating,  of  intercostal,  794. 
of  thigh,  803. 


—  plantar,  813. 

—  radial,  792. 

—  of  shoulder,  784. 

—  of  S(Emmering,  807. 

—  tibial,  803. 
■  ulnar,  dorsal,  789. 


deep  palmar,  789. 

■ plantar,  814. 

temporal,  835. 

dental,  anterior,  834. 

inferior,  837. 

posterior,  833. 

descendens  noni,  853. 

descending  cervical,  779. 
internal,  777. 

diaphragmatic,  780. 

digastric,  840. 

digital,  of  median,  788 
of  radial,  792. 

of  ulnar,  789. 

dorsal,  branches  of,  anterior,  794. 
-  posterior,  77S 


~  number  of,  771. 

—  roots  of,  772. 

—  collateral  of  fingers,  790,  792. 
—  toes,  8)1. 

—  of  foot,  deep  external,  811. 
—  internal,  811. 


—  of  hand,  external,  792. 
internal,  790. 

—  intercostal.    See  Intercostal. 

—  of  penis,  806. 


■  dorsi-lumbar,  796. 

-  to  dura  mater,  835. 

•  encephalic.     See  Crtmidl. 

■  ethmoidal,  830. 

■  facial.    See  Portio  Dvra. 

branches,  collateral,  839. 

summary  of,  848. 

•  to  femoral  artery,  802. 

-  frontal,  828. 


Nerves,  frontal,  external,  829. 

—  internal,  829 

—  osseous,  829 


-  fronto-nasal,  829  (nole^ 

-  for  gastrocnemius,  812. 

-  for  gemelli,  808. 

-  genito-crural,  799 

■  glosso-pharyngeal,  distribution  of,  843. 

function  of,  845. 

ganglion  of,  844. 

origin  and  cranial  course, 

823. 

■  gluteal,  inferior,  807. 
•  superior,  807. 


•  gustatory,  836. 

•  hemorrhoidal,  inferior,  806. 
■  to  hip-joint,  800  (note), 
-hypo-glossal,  distribution,  851. 

function,  853. 

ganglion,  823. 

origin  and  cranial  course,  824 


-  ilio  inguinal,  798. 

scrotal,  798. 

small,  798. 

-  incisor,  837. 

•  infra-hyoid,  of  hypo-glossal,  852. 

orbital,  831,  841. 

of  facial,  841. 


trochlear,  830. 


■  inguinal,  external,  797. 
■  internal,  797. 


■  ingnino-cutaneous,  797. 

■  intercostal,  794. 

muscular,  794. 

perforating,  794. 

summary  of,  796. 


■  costo-humeral,  795. 

■  osseous,  anterior,  of  forearm,  79d. 
of  leg,  811. 

■  posterior,  of  foreann,  790. 


■  ischiadic,  802. 

lesser,  802. 


■  of  Jacobson,  838. 

■  lachrymal,  828. 
of  orbital,  831. 


lachrymo-palpebral,  888. 
•  laryngeal,  anastomotic,  847. 

external,  846. 

inferior,  or  recurrent,  847. 

superior,  846. 

'  of  sympathetic,  859. 


■  to  latissimus  dorsi,  784. 

■  levator  angul  i  scapulae,  782. 
•  ani,  805. 


■  lingual,  836. 

•  of  glosso-pharjmgeal,  844. 


■  longitudinal,  of  Lancisi,  737. 

■  lumbar,  branches  of,  anterior,  796. 
posterior,  776. 


number  of,  772. 
roots  of,  772. 


■  lumbo-sacral,  797. 
'  malar,  831. 
of  facial,  840 

■  masseteric,  835. 

■  mastoid,  great,  779. 
■  small,  780. 


•  maxillary,  inferior,  834. 

superior,  831. 

terminal  blanches  of,  834L 


■  median,  786. 

in  arm,  786.^ 

in  forearm,  787. 

■  in  hand,  787. 


-  mental,  837 

of  facial,  841. 

■  motor  oculi,  common,  distribution  of,  825. 
function  of,  826. 


origin  and  cranial  course, 

820. 
external,  distribution,  838. 

origin  and  cranial  course. 

822. 


•  musculo-cutaneous,  brachial,  786, 

. crural,  801. 

— dorsal,  775. 

■  of  leg,  810. 


-  lumbar,  inferior,  798. 

— middle,  798. 

superior,  798 


INDEX. 


Nerves,  musuulo-spiral,  786,  791. 

myloid,  837. 

nasal,  829. 

• external,  829. 

internal,  830. 

— — posterior,  832. 

superior,  833. 

■  of  nasal  fossa,  external,  830. 

naso-lobar,  830. 

palatine,  832. 

obturator,  799. 

accessory  of,  800  (note). 


articular  of,  to  hip,  800. 

'  knee,  801  (not«). 


'  long  cutaneous,  801  (note). 


■  to  obturator  iiitemus,  805. 

■  occipital,  external,  779. 
great,  777. 

-  small,  780. 


■  oculo-muscular.  See  Motor  Oculi  and  Pathetic. 

■  oesophageal,  847. 

■  olfactory,  bulb  of,  817. 
distribution  of,  824. 

function  of,  825. 

origin  and  cranial  conrse,  818. 

structure  of,  818. 

■  ophthalmic,  827. 

■  optic,  chiasma  or  commissnre  of,  819. 

distribution  of,  825. 

function,  825. 

origin  and  cranial  course,  819. 

roots  of,  gray,  608. 

'  structure,  820. 


Nerves,  popliteal,  sciatic,  external,  808. 
internal,  811. 


portio  dura,  distribution,  839, 

function,  843. 

"^ ■ origin  and  cranial  course,  82S. 

mollis,  distribution,  681,  842. 

function,  842. 

origin  and  cranial  course,  63S. 

structure,  768. 


•  pterygoid,  833 

internal,  836. 


•  pudendal,  long,  808. 

•  pudic,  internal,  806. 
■  in  female,  807 


pulmonary,  anterior  and  posterior,  848. 

to  pyrifonnis,  807. 

for  quadratus  femoris,  I 


—  radial,  or  musculo-spiral,  790. 
proper,  791. 

—  to  rectus  femoris,  802. 

—  recurrent,  of  knee,  810. 
^— ^— ^^—  laryngeal,  648. 

lesser  sciatic,  8081 


--  terminations  of,  671. 
tracts  of,  819. 


■  orbital,  831. 

of  facial,  840. 


'  palatine,  anterior,  832. 

middle,  832. 

posterior,  832. 

■  palmar  collateral,  769,  790. 
'  cutaneous,  768. 


•  palpebral,  inferior,  840. 
■  superior,  840. 


of  particular  organs,  parts,  or  tissues.     See 

those  organs,  &c. 

par  Tagnm.     See  Pneumogastric. 

pathetic,  distribution,  826. 

function,  826. 

origin  and  cranial  course,  820. 

to  pectineus,  801  (note),  802  (note). 

■  pectoralis  major,  783. 

•  minor,  783. 


•  perforans  Casserii,  786. 
■  perforating,  of  hand,  790. 

cutaneous,  of  inter-costalsj 

thigh,  802. 


'  perineal,  806. 

superficial,  anterior,  806. 

posterior,  806. 


-  peroneal,  808. 

cutaneous,  810. 

external,  810. 

saphenous,  810. 

'  petrosal,  superficial,  great,  833. 

small,  838. 

■  pharyngeal,  of  glosso-pharyngeal,  844. 
'  pneumogastric,  646. 


small,  846,  850. 

of  spheno-palatine,  833  (note). 

sympathetic,  859. 


■  phrenic,  780. 

■  plantar,  collateral,  813,  814, 
external,  814. 

■  deep,  814. 


internal,  813. 


'  for  plantaris  longus,  812. 

'  pneumogastric,  in  abdomen,  846. 

anastomoses  of,  845. 

cranial  course,  823. 

fibrous  layers  of,  719. 

in  foramen  lacerum,  645. 

functions  of,  849. 

ganglion  of,  845. 

in  neck,  845. 

origin  of,  823. 

summary  of,  849. 

in  thorax,  847. 


■  popliteal,  external,  808. 
internal,  812. 


■  renal,  865. 

•  respiratory,  external,  782. 

of  eye,  891. 

superior,  of  trunk,  850. 


■  to  rhomboideus,  782 

■  sacral,  branches  of,  anterior,  804. 
posterior,  777. 


—  number  of,  772. 
roots  of,  772. 


'  saphenous,  external,  812. 

internal,  803. 

accessory,  of,  802 


—  peroneal,  810. 


'  satellite,  of  femoral  artery,  803. 
•  ulnar  artery,  790. 


■  sciatic,  great,  808. 
lesser,  801. 


■  of  septum  nasi,  anterior,  830. 
posterior,  832. 


■  to  serratus,  ' 

■  of  sheath  of  femoral  vessels,  SOS, 

■  soft  (nervi  molles),  845. 

■  spheno-palatine,  external,  833. 
—  internal,  832. 


•  spinal,  770. 

—  accessory  of  Willis. 


—  branches  of,  in  general,  771 

anterior,  771. 

ganglionic,  771. 

posterior,  773. 


See  AcctMorf, 


■  classification  of,  770. 

■  number  of,  770. 
•  origin  of,  apparent,  770. 

real,  772. 


plexuses  of,  776. 


—  roots  of,  anterior,  or  non-ganglionic,  77L 
—  roots  of,  posterior,  or  ganglionic,  Til 


'  splanchnic,  great,  865. 

lesser,  865. 

lumbar,  869. 


■  splenic,  867. 
-  to  splenius,  843. 

■  sternal  cutaneous,  780. 
•  styloid,  840. 

■  to  sub-clavius,  782. 

■  sub-occipital,  anterior  branch,  778. 
•  posterior,  776. 


■  scapular,  inferior,  784. 
superior,  783. 


■  of  sub-septum,  841. 


superficial  cardiac,  862.  • 

cervical,  776. 
petrosal,  great,  633. 
lesser,  637. 


■  temporal,  835. 


•  supra-clavicular,  779. 

orbital,  828. 

scapular,  782. 

'  trochlear,  829. 


5X 


to  supra  and  infra-spinati,  782. 

sympathetic,  in  general,  761. 

characters  of,  871. 

structure  of,  766. 

in  particular,  854. 

abdominal,  851. 

I  cervical,  855. 
lumbar,  848. 


898 


INDEX. 


Nervei,  sympathetic,  sacral,  871. 

—  thoracic,  868. 

temporal,  deep,  835. 

of  facial,  839. 

--  superficial,  836. 


•  temporo-facial,  839. 
malar,  831. 


'  to  tensor  tympani,  837. 

vagins  femoris,  807. 


•  tentorium  cerebelli,  ffl7. 
■  teres  major,  874. 
minor,  783. 


•  thoracic,  783. 

anterior,  783. 

—  posterior,782. 


-tibial,  811. 

anterior,  811. 

cutaneous,  802. 

posterior,  811. 

saphenous,  813» 

•  to  trapezius,  781. 

•  trifacial,  distribution  of,  827. 

divisions  of,  827. 

ganglion  of,  821. 

'  origin  and  cranial  course,  821. 


root  of,  large,  821. 

small,  821. 

■trigeminal.     See  Tfifaeiat. 

■  trochlear.     See  Pathetic. 

■  tympanic,  of  Jacobson,  838. 
•  ulnar,  789. 

in  the  arm  and  fo(re8rm>  789. 

-  hand,  790. 


-  for  ulnar  artery,  790. 

-  uterine,  870. 

-  vaginal,  870. 

-  for  vasti  femoris,  802. 

-  vertebral  (sympathetic),  860. 

■  vesical,  870. 

■  vestibular,  843. 

■  vidian,  833. 

■  visceral,  abdominal,  866. 

cervical,  845. 

pelvic,  869 

■  sacral,  805 


Nervi  moUes,  845. 

Nervous  system,  central  portion,  681. 

peripheral  portion,  769.1 

Nervut  impar,  698. 
Neurilemma  of  nerves,  766. 

spinal  cord,  697. 

Neurology,  629. 

Ninth  nerve.     See  Nerve,  hypoglossal. 

Nipples,  472. 

glands  and  papillte  of,  473. 

Noduli  Arantii,  479. 
Nodulus  of  cerebellum,  716  (note). 
Nodus  encephali  (Soemmering),  844- 
Ncsud  de  I'encephale,  844. 
Nost,  general  description,  641. 

bones  of,  55,  641. 

cartilages  of,  641. 

mucous  membrane  of«  MStt 

'    muscles  of,  643. 

septum  of,  56,  642. 

skin  of,  643. 

Nostrils,  641. 

cartilages  of,  641. 

Notch,  inter-cocSyloid,  91. 

ischiatic,  89. 

-—^—  sacro-sciatic,  89. 

great,  15S. 

small,  156. 

sciatic,  89. 

'  sigmoid,  57. 

Notches,  vertebral,  20,  31. 
Nutritious  arteries.    See  Arteries. 

foramina  of  bones.    See  Fontmen. 

Nympha,  471. 

■Obligue  muscles.     See  Musclet. 
'Obturator  foramen  and  groove,  88. 

nerve.    See  Nerves. 

'  Occipital  angle  of  DaubentOB,  45. 

bone,  33. 

condyles,  33< 

crests,  34. 

foramen,  34. 

fossae,  34. 

'  nerves.    See  iVerM*. 


Occipital  protuberances,  34. 
veins.     See  Veins. 
Occt7>ito-atlantoid  articulations,  118 
ligaments,  118. 


'  axoid  articulations,  119. 
'  ligaments,  l20. 


parietal  suture,  46, 
OcuZo-muscular  nerves.    See  Nenitt,  Motwr  Oaii  tad 

Pathetic. 
Odontoid  process,  26. 
Odontogeny,  184. 
Odontology,  177. 
(Esophagus,  350.  • 

glands  of,  352. 

ihooous  membrane,  352. 

muscular  coat,  351. 

structure  of,  351. 

uses,  352. 

vessels  and  nerves,  3S3, 
OUcranoid  cavity,  80, 
Olecranon  process,  80. 
Olfactory  nerve.     See  Nervtt 


■  lobes,  758. 


Olivary  process,  37, 
bodies,  703. 

corpus  dent&taiB  of,  704. 

sections  of,  704. 

structure  of,  706. 


fasciculi,  705. 


Omentum,  colic,  478  (note). 
-  gastro-colic,  478. 

hepatic,  476. 

—  splenic,  408. 


■  great,  476. 

layers  of,  anterior,  476. 

-posterior,  476. 


«ac  of,  477. 

vessels  and  nerves  of,  478. 


lesser,  476. 

layer  of,  anterior,  476. 

posterior,  476. 


Operculum  laryngis,  426, 
Ophthalmic  nerve,  828. 
Optic  thalami,  727,  745. 

fibres  of,  746, 


tracts,  820. 

Orbicular  ligaments  of  joints.-    See  Ligaments. 
Orbital  arch,  36. 
cavities,  6 
fissure,  53. 

foramina,  internal,  36. 
process  of  palate  bone,  6S. 
processes  of  frontal  bone,  36. 
plate,  36. 
Orbits,  62. 

Organ  of  hearing,  665.    See  Ekir. 
sight,  645,    See  Eye. 

smell,  641,    See  Nose,  &aA  Pituitary  Mttnbrcoi*. 
taste,  639.     See  Tongue. 
touch,  629.     See  Skin. 
the  voice,  422.     See  Larynx. 
Organs,  anatomical  elements  of,  320. 
colour  and  consistence  of,  321. 
development  of,  321, 
of  digestion,  322, 
direction  and  relations  of,  3S1. 
dissection  of,  322, 
functions  of,  322, 
of  generation,  female,  46], 
male,  446. 


genito-urinary,  435, 
nomenclature,  320, 
number,  320. 
of  respiration,  409. 
of  the  senses,  629. 
situation,  320. 
size  and  figure,  321. 
structure  of,  321. 
urinary,  435. 
Os,  bone.    See  Bone,  oi. 
tincsE,  465. 
uteri,  465. 
Ossa  pisiformia,  or  lingualia.  111. 

triquetra,  or  Wormiana,  50. 

Ossicula  auditOs,  669. 

movements  of,  675. 
muscles  belonging  to,  674. 


Ossification  of  bones.    See  those  bones 
Osteology,  5. 
Osteogeny,  16. 


INDEX. 


899 


Ottia  of  Fallopian  tube,  463. 
Ottium  internum  of  uterus,  465. 
Otoconia  and  otolithes,  843. 
Ova  of  Naboth,  466. 
Ovarian  vesicles,  463. 
Ovaries,  461. 

•  ligaments  of,  461. 


-  structure,  463. 


Ovum,  462 

Palate,  bone,  53. 

hard,  330. 

development,  330. 

structure,  330. 

uses,  330. 

soft,  330. 

-  aponeurosis  of,  331. 
—————  development  of,  333. 

glands  of,  333. 

— — — —  mucous  membrane  of,  SSS. 

muscles  of,  331, 
pillars  of,  331. 

■  structure  of,  331 


—  uses  of,  331. 
—  vessels,  &c.,  of,  333. 


Palatine  aponeurosis,  331. 

arch,  329. 

canals,  52,  54. 

accessory,  53,  54. 

glands,  330. 

•  process,  52. 


Palm  of  hand,  83. 

Palmar  arteries.    See  Arteries. 

ligaments.    See  Ligament*. 

nerves.    See  Nerve*. 

Pancreas,  400. 

development  of,  409. 

duct  of,  402. 

function  of,  402. 

lesser,  402. 

structure  of,  401. 

1 vessels  and  nerves  of,  408. 

Panniculus  adiposus,  629. 

camosus,  629. 

Papula,  conjunctival,  648. 

dental,  181. 

(Goodsir),  183. 

of  kidney,  437. 

— — —  lachrymal,  646. 

of  skin,  630. 

~  of  small  intestine,  367. 

of  stomach,  361. 

of  tongue,  333. 

Par  vagum.     See  Nerve,  pneumogoitric 
Parietal  bone,  41. 

foramen,  41. 

■-  fossa,  41. 

protuberance,  41. 

Parotid  dnct,  341. 

gland,  340. 

development  of,  340  (note). 

structure  of,  340. 

Pars  mastoidea  of  temporal  bone,  43. 

petrosa  of  temporal  bone,  43. 

squamosa  of  temporal  bone,  43. 

Patella,  95. 

ligament  of,  97. 

Pathetic  nerve.     See  Nerve*. 


Patte  d'oie,  270,  271. 

Peduncles  of  cerebellum  and  cerebram. 

gans. 
Pelvis,  aponeuroses  of,  306. 

articulations  of,  154. 

•^—^  axes  of,  90. 

•  circumferences  of,  92. 

•  compared  with  shoulder,  lOS. 
. development  of,  general,  93. 

'  in  general,  90, 

■  great  or  false,  90. 

of  the  kidney,  439. 

: structure  of,  439. 

little  or  true,  90. 

brim  of,  92. 

strait,  superior,  92, 

■  inferior,  92. 


See  those  or- 


mechanism  of,  158-159. 
regions  of,  90. 
'  varieties  of,  sexual,  90. 


excavation  or  cavity  of,  12S. 
outlet  of,  92. 


Penis,  454. 

corpus  cavemosum  of,  455. 

glans  of,  461. 

ligament,  suspensory  or  triangular,  45A 

muscles  of,  457. 
Perforated  spot,  anterior,  734. 

■  posterior,  730. 

Perforating  arteries.    See  Arteries. 
nerves.    See  Nerve*. 


Pert-cardium,  494. 

structure,  494. 
vessels,  495. 


Peritoneum,  474. 

folds  of,  478. 

general  description  of,  478. 

portion  of,  parietal,  478. 

sub-umbilical,  474. 

supra-umbili(^,  474 

visceral,  477. 


structure  of,  479. 
Permanent  teeth.  See  Teeth. 
Perone,  98. 

Peroneal  arteries.     See  Arteries. 
See  Nerve*. 


Pes  accessorius,  746. 

hippocampi,  745. 

Petrosal  nerves.  See  Nerves.  ^ 
Petrous  portion  of  temporal  bone,  4S. 
process,  43. 


'  glottis,  640. 
•  lymph,  679. 
'  osteum,  296. 

'  alveolo-dental,  338. 


Pharyngeal  nerves.    See  Nerve*. 
Pharynx,  344. 

aponeuroses  of,  346. 

development  of,  349. 

mucous  membrane  of,  319. 

muscles  of,  346. 

extrinsic,  346. 

intrinsic,  346. 

supernumerary,  346. 


uses,  349. 

vessels  and  nerves,  349. 
Pia  mater,  692. 

cerebral,  692. 

spinal,  or  rachidian,  697. 


Pigmentum  of  skin,  632  (note) 
eye,  659, 


Pillar  of  valve  of  Vieussens,  712. 
Pillars  of  diaphragm,  212. 

-  fauces,  or  palate,  331. 
fornix,  740. 


Pineal  gland  or  body,  742. 

-  commissure  and  peduncles  of,  743. 

-  concretions,  743. 
function  of,  744. 


Pisiform  bone,  83. 

Pt<utM,  749. 

Pituitary  body  or  gland,  729. 

-  fossa,  37. 

—  membrane,  643. 

follicles  of,  645. 

nei  ves  of,  645. 

structure,  644. 

vessels  of,  645. 

Plantar  ligaments.    See  Ligaments. 
nerves.    See  Nerves. 


Plaques  gaufries,  '. 

Plate,  cribriform,  of  ethmoid  bone,  40. 

-  horizontal,  of  palate  bone,  53. 

-  orbital,  35. 

-  perpendicular,  of  ethmoid  bone,  41. 

Pleura,  costal,  diaphragmatic,  mediastinal,  and  polnto 
nary,  413. 

structure  and  uses  of,  413. 


Pleura:,  413. 

Plexuses  of  lymphatics,  614. 

of  nerve,  762,  et  infra. 

auricular,  858. 

brachial,  781. 

general  view  Ofnerrei  of,  79S> 


'  bronchial,  848. 
•  cardiac,  deep,  860. 
great,  863. 


'  carotid,  856. 


■  superficial,  862. 


—  cavernous,  856. 

—  cervical,  777. 
deep,  777. 


900 


INDEX. 


Plexuses,  cervical,  posterior,  774. 

superficial,  777. 

— ■^-—  cervico-brachial,  77(i 

coeliac,  866. 

coronary,  of  heart,  anterior  and  posterior,  863, 

of  stomach,  866. 


'  diaphragmatic,  I 
'  epigastric,  866. 
'  facial  (sympathetic),  858. 
'  gastro-epiploic,  left,  868. 
•  right,  867. 


—  hemorrhoidal,  inferior,  890. 
snporior,  868. 


■  hepatic,  867. 

•  hypogastric,  870. 

■  infra-orbital,  841. 

•  laryngeal,  846. 
'  lingual,  858. 

'  lymphatic,  612, 

.  lumbar,  797. 

'  lumbo-aortic,  868,  869. 

sacral,  776. 

'  mental,  837. 
'  mesenteric,  inferior,  868. 
superior,  867. 


■  nervous,  762. 

■  occipital,  859. 

■  ovarian,  868. 

•  pharyngeal,  846,  859. 

•  phrenic,  866. 

■  pulmonary,  anterior  and  poBtraior,  848. 

•  renal,  868. 

■  sacral,  805. 

•  solar,  866. 

■  spermatic,  868. 

■  splenic,  867. 

'  supra-renal,  866. 

•  thyroid,  858. 

•  tympanic,  843. 

•  uterine,  870. 
'  vertebral,  860. 


vesical,  870. 

visceral  of  abdomen,  866. 

pelvis,  805,  869 


■  of  veins,  575,  et  infrd. 
alveolar,  589. 
choroid,  of  brain,  747. 

fourth  ventricle,  730. 

■  third  ventricle,  741. 
-  reflected  portion  of,  746. 


■  hemorrhoidal,  601. 

■  intra-spinal,  609. 

•  lingual,  590. 

■  masseteric,  590. 

•  pampiniform,  598. 
'  pharyngeal,  591. 

•  pterygoid,  590. 

■  spermatic,  598. 

'  spinal,  deep,  609. 
■  longitudinal,  609. 

-  transverse,  609. 


'  tonsillar,  333. 
'  uterine,  602. 
'  vaginal,  60S. 
■  vesico-prostatic,  601. 
urethral,  602. 


Plica  semilunaris,  648. 
Pneumo-gastric  nerve.    See  Nene. 
Pomum  Adami,  424. 
Pons  Varolii,  or  cerebelli,  710. 

internal  structure  rf,  718. 

Porta,  388. 

Portia  dura  nerve.    See  Nerve. 

mollis  nerve.    See  Nerve. 

Prepuce,  454. 

of  clitoris,  471. 

frcenum  of,  454. 

Process,  acromion,  76. 

auditory,  44. 

basilar,  34. 

cochleariform,  44,  673. 

-  coracoid,  76. 
— — —  coronoid,  of  lower  jaw,  58. 

of  ulna,  80. 

ensiform,  65. 

of  fifth  metatarsal  bone,  104.    

'  genial,  58. 


—  gracilis  of  Raw,  673. 

—  hamular,  of  sphenoid  bone,  37. 
of  cochlea.  678. 


Process,  of  helix,  667. 

■  malar,  51. 

■  mastoid,  43. 

■  mental,  58. 

■  nasal,  51. 

■  odontoid,  26. 
'  olecranon,  80. 


—  olivarv,  37. 

—  orbital,  external,  36. 
■  internal,  36. 


—  of  palate  bone,  M. 


palatine,  52. 
'  petrous,  43. 
'  pyramidal,  54. 
'  scaphoid,  101. 
'  styloid,  of  temporal  bone,  4S. 

ulna,  80. 

■  radius,  81. 

fibula,  99. 


'  vaginal,  of  temporal  bone,  44. 


—  vermiform,  inferior,  716. 
■  superior,  716. 


'  zygomatic,  of  temporal  bone,  43. 
of  malar  bone,  55. 


Processes  of  bones,  9. 

ciliary,  of  choroid  coat,  656. 

vitreous  humour,  661 


calcaneal,  101. 
clinoid,  37. 
pterygoid,  37. 
spinous,  of  ilium,  89. 
spinous,  of  vertebne,  21. 
Processus  a  cerebello  ad  meduUam,  704. 

pontem,  721. 

testes,  711. 


'  a  cerebro  ad  meduUam,  710. 
•  arciformes,  703. 
—  gracilis  of  Raw,  673. 


Profunda  artery.    See  Arteries. 
vein.     See  Veins. 


Promontory  of  sacrum,  26,  92. 

tympanum,  671. 

Pronator  muscles.     See  Musclet, 
Protuberances,  occipital,  34. 
parietal,  42. 
Psalterium,  738. 
Pterygoid  canal,  37. 

columns,  126. 

fossa,  37. 

processes,  37. 

P/ery^o-maxillary  fissure,  52. 
palatine  canal,  38,  52. 


Pubes,  90. 

Pubic  arch,  89. 

Pudic  arteries.     See  Arteries. 

Pulmonary  arteries.    See  Arteries. 

veins.     See  Veins. 

Puncta  lachrymalia,  647. 
Pupil  of  eye,  657. 
Pupillary  membrane,  659. 
Pyloric  valve,  355. 
Pylorus,  354. 

antrum  of,  354. 

Pyramid  of  cerebellum,  or  of  Malacame,  717. 

of  tympanum,  and  its  canal,  671. 

Pyramids,  anterior,  703. 

decussation  of,  706. 

sections  of,  706. 


■  of  kidney,  437. 


posterior,  704. 

sections  of,  706. 


Quadrati  muscles.     See  Muscles. 

Rachis.     See  Vertebral  Column. 

Rachidian  bulb,  proper.    See  Medulla  Oblongata. 

bulbs,  697. 

veins.    See  Veins,  spinal. 

Radial  nerve.     See  Nerve. 
Radiating  crown  of  Reil,  744. 
Radius,  81. 

^  and  tibia,  lower  parts  of,  compared,  107. 

Ra/ni  of  lower  jaw,  57. 
Ramus  of  pubes,  90. 

ischium,  91. 

Receptaculi  arteriie,  525. 
Receptaculum  chyli,  618. 

ganglii  petrosi,  843. 


Recess  of  tympanum,  672. 
Recessvs  sulciformis,  676. 


INDEX. 


901 


Recti  muscles.    See  Muteltt, 
Rectum,  376. 

columns  of,  377. 

curves  of,  377. 

■  internal  surface,  378. 


muscular  coat  of,  377. 

structure  of,  377. 

Recurrent  arteries.     See  Arteriet. 

nerves.    See  Nerves. 

Renes.     See  Kidneys. 

succenturiati.    See  Supra-renal  Capsules. 

Respiratory  apparatus,  409. 

nerves,  in  particular.    See  Nerves. 

Restiform  bodies,  704. 
Rete  of  Malpigbi,  640. 

mucosum,  640. 

of  tongue,  646. 

yasculosum  testis,  451. 

Reiia  mirabilia,  496. 
Retina,  660. 

artery  of,  660. 

folds  of,  660. 

foramen  centrale,  and  limbnt  Inteua  of,  660. 

• margo  dentatus,  660. 

structure  of,  660  (note). 

termination  of,  660  (note). 

Ribs,  angles  of,  68. 

characters  of,  general,  67. 

— special,  68. 

false,  67. 

movements  of,  134. 

supernumerary,  32. 

true,  67. 

torsion  of,  67. 

tubercle  of,  68. 

Rima  glottidis,  434. 

palpebrarum,  646L 

Ring,  crural,  310. 

inguinal,  310. 

umbilical,  308. 

Rostrum  of  cochlea,  676. 

of  corpus  callosum,  787. 

Rotula,  95. 

Rugee,  vaginal,  468. 

Sac,  lachrymal,  652. 
Sacculus  vestibuli,  680. 

or  sinus  laryngis,  434. 

Sacral  arteries.     See  Arteries. 

canal,  27. 

foramina,  27. 

nerves.    See  Nerves. 

vertebne.    See  Vertebra  and  Vertebra.. 

Socro-coccygeal  vertebne,  26. 

sciatic  notch,  92. 

vertebral  angle,  or  promontory,  90. 

Sacrum,  26. 

promontory  of,  26. 

— — —  small  comua  of,  27. 
Saliva,  396. 
Salivary  glands,  340. 
Saphenous  nerves.    See  Nerves, 
Satellite  arteries.    See  Arteries. 

• —  nerves.    See  Nerves. 

Scaphoid  bone  of  carpus,  83. 

of  tarsus,  101. 

'  process,  101. 
Scapula,  75. 

Scapular  arteries.    See  Arteries. 
Schindylesis,  114. 
Sciatic  notch,  89. 

spine,  89. 

Scrobiculis  cordis,  354,  482. 

Scrotum,  447. 

Second  cranial  nenre.    See  Nerve,  optic. 

Sella  turcica,  37. 

Semen,  453. 

Semi-circular  canals,  and  their  ampulle,  677. 

membranous,  680. 

lines  of  occipital  bone,  33. 


lunar  bone,  83. 

■  ganglion,  of  fifth  nerve,  843. 


Seminiferous  tubes,  454. 

Septa,  inter-muscular,  294. 

— ^— — ^-^— — ^— —  of  arm,  315. 

of  thigh,  306. 

Septum  crarale,  303. 

of  dartos,  446. 

inter-auricular,  482. 


Seytum,  inter-ventricular  (of  brain),  518. 
(of  heart),  481 


•  lucidum,  738. 


layers  of,  738. 

ventricle  of,  738. 

nasal,  artery  of,  518. 

cartilaginous,  642. 

osseous,  56,  62. 


pectiniforme,  454, 

Serrati  muscles.     See  Muscles. 
Sesamoid  bones,  96. 

of  hand,  153. 

of  foot,  177. 

of  gastrocnemius,  164. 

Seventh  cranial  nerve.    See  Nerve,  Portio  Dura,  aiui 

Portio  Mollis. 
Sheath  of  brachial  vessels,  316. 

-  femoral  vessels,  310. 

-  for  muscles,  296. 
of  arm,  316. 

thigh,  311. 


■  synovial,  178. 

■  for  tendons,  397. 
around  carpus,  319. 

-  -  tarsus,  314. 


•  for  vessels,  396. 


'  structure  of,  397. 


Shoulder,  aponeuroses  of,  315. 

bones  of,  73. 

compared  -with  pelvis,  105. 

development  of,  general,  77. 

in  general,  77. 


Sigmoid  cavities,  great  and  small,  80. 

-  flexure,  371. 

-  notch,  57. 

-  valves,  484. 

Sinus,  or  sinuses,  aortic,  498. 

basilar,  587. 

of  bones,  1 1 . 

of  bulb  of  urethra,  459. 

cavernous,  587. 

circular,  of  Ridley,  588. 

common,  of  vestibule,  680. 

confluences  of,  588. 

■     coronary,  of  heart,  577. 

of  Ridley,  587. 

of  dura  mater,  583. 

ethmoidal,  43. 

frontal,  36. 

of  internal  jugular,  583 

lateral,  or  transverse,  584. 

of  larynx,  or  sinus  of  Morgagui,  584- 

longitudinal,  inferior,  586. 

superior,  584. 


—  maxillary,  52. 
-^  of  Morgagni,  461. 

—  occipital,  anterior,  587. 
posterior,  587. 


'  ophthalmic,  587. 
'  petrosal,  inferior,  586. 
superior,  566. 


—  prostatic,  459. 

—  sphenoidal,  40. 

—  straight,  585. 

—  transverse,  or  lateral,  984. 

—  of  urethra,  459. 

—  uterine,  602. 
>-  of  Valsalva,  498. 

—  of  veins,  575. 

—  of  vena  ports,  599. 

—  venosus  (heart),  492. 
Sixth  cranial  nerve.    See  Nerve. 
Skeleton,  general  view  of,  5. 

natural,  5. 
artificial,  5. 


Skin,  629. 

appendages  of,  635. 
characters,  external,  629. 
Spine,  cutis  or  dermis  of,  630. 

epidermis  of,  632  (note). 

follicles,  sebaceous,  627. 

functions  of,  627. 

glands,  sudoriferous,  632. 

lymphatics  of,  631. 

papilla  of,  639. 

pigmentum  of,  631,  632  (note). 

pores  of,  632. 

rete  mucosum,  633  (note). 

structure  of,  630-634. 

true,  630. 


^P^2 

Skull,  33      See  Cranium  and  Face. 

Socio  parotidis,  341. 

Sole  of  foot,  102. 

Solitary  glands.    See  Glands. 

Space,  inter-peduncular,  711,  728. 

Spaces,  inter-costal,  71. 

osseous,  hand,  84. 

foot,  106. 


INDEX. 


'  sub-arachnoid,  688. 


Sphenoidal  cells,  or  sinuses,  39. 

fissure,  39. 

Sphenoid  bone,  37. 
S;)Aeno-frontal  suture,  47. 

jugal  suture,  47. 

maxillary  fissure,  39,  5S. 

'  fossa,  60. 


■  occipital  bone,  36. 
~  suture,  47. 


palatine  foramen,  54. 

parietal  suture,  47. 

spinous  foramen,  39. 

temporal  fossae,  48. 

suture,  47. 

Sphincter  muscles.     See  Muscles. 

Spinal  accessory  nerre.     See  Nerve,  accessory. 

arteries.     See  Arteries. 

cord,  693. 

— ■ arachnoid  of,  690. 

enlargements  of,  cervical,  lumbar,  and  oc- 
cipital, 697. 
■  enveloped  in  its  proper  membrane,  697. 

extent  and  situation  of,  694. 

form,  direction,  and  relations  of,  696. 

furrows  or  grooves,  698. 

— ^— — ^—  membrane  proper,  or  neurilemma  of,  697. 

pia  mater  of,  697. 

■  sections  of,  700. 

structure  of,  internal,  700. 

examined  by  hardening,  702. 

■  sections,  700. 

water,  701. 

substance,  gray  and  white,  702. 

•  minute  structure,  702  (note). 


•  ventricles  of,  702. 


See  Vertebral  Column. 


muscles,  posterior.     See  Muscles. 

nerves.     See  Nerves. 

veins  and  plexuses.    See  Veirts. 

Spine,  nasal,  anterior,  52. 

posterior,  54« 

of  ischium,  89. 

of  pubes,  89. 

of  scapula,  75. 

sciatic,  89. 

or  spinal  column,  18. 

of  tibia,  97. 

Spinous  foramen  of  sphenoid,  39. 

processes  of  ilium,  89. 

of  vertebrsE,  19,  31. 

Splanchnic  nerves.    See  Nerves. 
Splanchnology,  320. 
Spleen,  403. 

cells  of,  405. 

coats  of,  405. 

• corpuscules  of,  407. 

development  of,  407. 

•  fissure,  or  hilus,  405. 

functions,  408. 

lymphatics  of,  407. 

size  of,  differences  in,  403. 

■  structure  of,  405. 

vessels  and  nerves,  405,  408. 

Spleens,  supernumerary,  403. 
Splenic  artery,  406. 

omentum,  405. 

veins,  406. 

Spongy  bones.    See  Bone*. 
Stapes,  674. 
Stenonian  duct,  341. 
Sternum,  64. 
Stomach,  352. 

alveoli  of,  361. 

coat  of,  cellular  or  fibrous,  357. 

mucous,  356. 

muscular,  356. 

nervous  (so  called),  356, 

-  serous,  or  peritoneal,  357. 

culs-de-sac  of,  354. 

curvatures  of,  354. 

development  of,  361. 

extremities  of,  354. 


Stomach,  follicles  of,  360. 
function,  361. 
glands  of,  360. 
granular  appearance  of,  397. 


'  lymphatic  system  of,  360. 
'  orifices  of,  355. 
'  papillse  or  villi,  359. 
■  structure  of,  356. 
'  surface  of,  external,  353. 
'  internal,  355. 


tuberosity  of,  355. 

tubnli  of,  360. 

vessels  and  nerves  of,  360. 
Structure  of  tissues  and  organs.     See  those  organs  and 

tissues. 
Styloid  bone,  43. 

process  of  temporal  bone,  43. 

fibula,  99. 

radius,  81. 

ulna,  80. 


Sui-arachnoid  fluid,  690. 

uses  of,  692. 


■  space,  cranial,  anterior,  688. 
'  posterior,  686. 


spinal,  689  (note). 


lingual  fossa,  58. 

gland,  343. 

ducts  of,  343. 


maxillary  fossa,  58. 

gland,  342. 

duct  of,  342. 


synovial  adipose  tissue,  113. 

Sulci.     See  Cerebrum,  anfractuositiet  of. 
Super-ciliary  foramen,  36. 

ridge,  35. 

Superficial  petrosal  nerves.     See  Nerves. 
Supplementary  cavity  of  shoulder-joint,  139. 

of  temporo-maxillary  joint,  138. 

Supro-orbitary  foramen,  36,  59. 

renal  capsules,  development  of,  445. 

structure,  446. 

sphenoidal  fossa,  37. 

spinous  fossa,  76. 
Sustentaculum  tali,  101. 
Suture,  coronal,  or  fronto-parietal,  45,  47. 

ethmoido-frontal,  48. 

ethmo-sphenoidal,  48. 

fronto-jugal,  48,  59. 

maxillary,  59. 

nasal,  59. 

sphenoidal,  48. 

lambdoidal,  or  occipito-paxiet^,  40. 

maxiUary,  59. 

palatine,  60. 

petro-occipital,  47. 
sphenoidal,  48. 


■  sagfittal  or  bi-parietal,  46. 

■  spheno-frontal,  47. 

jugal,  47. 

parietal,  47. 

temporal,  48. 

■  squamous,  47. 

■  temporo-parietal,  47. 

■  transverse  or  spheno-occipital,  46,  49. 


Sutures,  114. 

indented,  squamous,  and  harmonic,  114. 

cranial,  in  general,  154. 
Sympathetic  ganglia  in  particular.     See  Ganglia^ 

nerves.     See  Nerves. 

plexuses,  in  particular.     See  Plexuset, 

system,  in  particular.    See  Ganglia  and 

Nerves. 
Symphyses,  characters  of,  114. 
Sympftysis  menti,  57. 

pubis,  89,  155. 

sacro-iliac,  155. 


Synarthroses,  114. 

characters,  ligaments,  and  motioni,  llSk 


Synchondroses,  113. 
Syndesmology,  111. 
Syneuroses,  li3. 
Synovia,  112. 
Synovial  bnrsae,  178. 

capsules,  113. 

of  particular  joints.  See  thov  joints 


'  fringes,  112. 

■  in  the  knee,  164. 


■  glands  (so-called),  112. 
membranes,  articular,  general  characters  of, 
112. 


INDXX. 


903 


Synovial  membranes,  bursal,  178,  298. 

■ minute  structure  of,  178. 

vaginal,  178,  299. 

sheaths  for  tendons,  178,  298. 

Syssarcostf,  114. 

Taenia  hippocsunpi,  746. 

semicircularis,  740,  745. 

Tarsus,  bones  of,  99. 

• first  row  of,  100. 

• ^_^____  compared  with  first  row 

of  carpus,  107. 
-^—————  second  row  of,  101. 
'  compared  with  second 

row  of  carpus,  107. 


■ compared  with  carpus,  108, 

sheaths  for  tendons  on,  313. 

Teeth,  177. 

arteries  of,  182. 

bicuspid,  179. 

bulbs  of,  181. 

canine,  180. 

cement  of,  182. 

changes  in,  after  eruption,  190. 

■ characters  of,  general,  179. 

— differential,  179. 

classification  of,  178. 

compared  with  bones,  183  (note). 

epidermoid  appendage*,  177. 


-  compound,  182. 

-  conformation  of,  external,  179. 
— internal,  181. 

-  cortical  portion  of,  181. 
substance  of,  proper,  182. 

■  crowns  of,  179. 

-  crusta  petrosa  of,  182,  and  note. 

■  cuspid,  179. 

-  development  of,  183. 
different  stages  of,  184. 

■  distinguished  from  bones,  177. 

■  enamel  of,  182. 

chemical  composition  of,  183. 

development  of,  186. 

structure  of,  183  (note). 

■  fangs  of,  178. 
■  formation  of,  186. 


Teeth,  wisdom,  181. 

uses  of,  189. 

two  sets  of,  189. 

Tela  choroidea,  731. 

Temporal  arteries.     See  Arteriei. 

bone,  42. 

fossa,  47. 

nerves.    See  Nerves. 


Temporo-pditietaX  suture,  47. 
Tendo  AchiUis,  283. 
Tendon  of  Zinn,  650. 

straight  of  orbicularis  palpebranun,  053 

Tendons  of  muscles,  193. 

structure  of,  299. 

Tensor  muscles.    See  Muscles. 
Tentorium  cerebelU,  684. 
Testes  (of  brain),  712. 
Testicles,  446. 

coverings  of,  446. 

excretory  duct  of,  452. 

proper  coat  of,  449. 

structure  of,  449. 

tubuli  of,  450. 

tunica  albuginea,  449. 

erythroides,  447. 

propria,  449. 

vaginalis,  447, 


-  vessels  and  nerves  of,  iSl. 


Testis,  coni  vasculosi  of,  452. 
mediastinum,  450. 
rete  vasculosum,  451. 
tubuli,  450. 


Testicular  artery,  451. 
Thalami  optic,  742. 

structure  of,  744. 


TAt^Abone  93. 

compared  with  arm  bone,  lOS. 
nird  cranial  nerve.    See  Nerve. 
Thoracic  arteries.    See  Arteries. 
Thorax,  aponeuroses  of,  300. 

-  articulations  of,  130. 

-  bones  of,  64. 
development  of,  geikersl,  73. 


-  follicles  of,  185. 
(Goodsir).  183  (note). 

-  general  idea  of,  190. 

-  incisor,  179 

-  ivory  of,  183.   ~ 

chemical  compomtion  of,  182. 

development  of,  165. 

structure  of,  183  (note). 

-milk.     See  Temporary. 
'  molar,  180. 

great  and  small,  180. 

upper  and  lower  compared,  181. 

■  multi-cuspid,  181. 

■  nerves  of,  181. 

•  number  of,  177. 

■  permanent,  177. 

decadence  of,  190. 

development  of,  190. 

differences  of,  from  temporary,  190. 

eruption  of",  189. 

— ■ follicular  stage  of,  184. 

origin  of  pulps  and  sac*  of,  164. 

papillary  stage  of,  184. 

—  saccular  stage  of,  185. 

■  provisional.    See  Temporary. 

■  pulps  of,  181. 
•  origin  of,  184. 


■  quadri-cuspid,  181. 

-  sacs  of,  186. 
origin  of,  184. 

-  simple,  183. 

■  structure,  general,  181. 
—  minute,  183. 

■  supernumerary,  187. 
tartar  of,  183. 

•  temporary,  177. 

development  of,  183. 

differences  of,  from  permanent,  190. 

■  eruption  of,  183. 

follicular  stage  of,  180. 

origin  of  pulps  and  sacs  of,  184. 

papillary  stage  of,  184. 

saccular  stage  of,  184. 

shedding  of,  188. 


-  general  description  of,  70. 

-  mechanism  of,  132. 

-  movements  of,  in  general,  134. 

one  rib  of,  132. 

7%yro-arytenoid  ligaments.    See  Chords  Yoctiei 
Thyroid  arteries.    See  Arteries.  • 

— —  veins.    See  Veins. 


Tibia,  ' 

and  ulna,  upper  parts  of,  compared,  107. 

radius,  lower  parts  of,  compared,  107. 

Tibial  arteries.    See  Arteries, 

nerves.    See  Nerves. 
Tissue,  adipose,  175. 

bony,  12,  13. 

cartilaginous,  174. 

ceUular,  298. 

elastic,  174. 

fibro-cartilaginoni,  17i. 
cellular,  298. 


fibrous,  298. 
ligmmentous,  174. 
muscular,  198. 
nervous,  757. 
tendinous,  289. 
Toes,  articulations  of,  174. 
bones  of,  104. 
phalanges  of,  104. 
Tongue,  332. 

bone  of,  333. 
development  of,  336. 
dorsum  of,  332. 
frsnum  of,  333. 
lymphatics  of,  646. 
median  cartilage  of,  333. 
mucous  membrane  of,  646. 
muscles  of,  333. 

extrinsic,  334. 

intrinsic,  334. 


—  nerves  of,  646. 

—  papills  of,  333. 

—  rete  mucosum  of,  646. 

—  structure  of,  334. 

—  uses  of,  339. 
■  vessels,  339. 


Ton-tils,  333. 

of  cerebellum,  718. 

Torcular  lIeroi)hili,  5S8. 


INDEX. 


TrabecuJa  of  corpus  cavernosum,  455. 
—————  spleen,  405. 
Trachea,  416. 

cervical  portion,  416. 

glands  of,  416. 

structure  of,  416. 

thoracic  portion,  416. 
-  vessels  and  nerves,  416. 


Tractus  spiralis  foraminulentus,  678. 
Tragic  fossa,  668. 
Tragus,  666. 

■  -  ligament  of,  666. 
Transversahs  muscles.     See  Muscles. 
Transverse  arteries.     See  Arteries. 

muscles.     See  Muscles. 

suture,  46,  47. 

veins.     See  Veins. 

7V«njti«rjo-spinalis  muscle.     See  MuseU. 
Trapezium,  83. 
Trapezoid  bone,  83. 

ligament,  136. 

Triangulares  muscles.     See  Muscles. 
Triceps  muscles.     See  Muscles. 
Trifacial,  or  trigeminal  nerve.     See  Nerve. 
Trochanteric  cavity,  or  fossa,  95. 
Trochanters  of  femur,  95. 

of  humerus,  79.  ' 

Trochlea,  femoral,  95. 

humeral,  79. 

of  orbit,  651. 

Trochlear  articulations,  characters  of,  &c.,  114. 

nerve.     See  Nerve,  pathetic. 

Trochoid  articulations,  characters  of,  &c.,  114. 
Tube,  Eustachian.     See  Eustachian  Tube. 

Fallopian,  463. 

T^ber  annulare.     See  Pons  Varolii. 

cinereuni,  729. 

Tubercle,  ash-coloured,  of  Rolando,  703. 
lachrymal,  645. 

laminated,  717. 

of  Lower,  488. 

Tidtercles  of  Santorini,  in  larynx,  424. 

in  nose,  640. 

Tuberrula  quadrigemina,  or  bigemina,  712, 

structure  of,  714. 

T\iberosities,  calcaneal,  102. 

of  femur,  95. 

of  humerus,  79. 

■  of  tibia,  97. 

Tuberositi/,  bicipital,  81. 

of  ischium,  89. 

maxillary,  51. 

Tubes  of  Bellini,  437. 

TViu/t  of  intestine.    See  Intestine. 

recti,  of  kidney,  437. 

of  testicle,  452. 

seminiferi,  452. 

'  of  stomach,  361. 

'     uriniferi,  convoluted,  437. 

straight,  437. 

T\ibulus  centralis  modioli,  679. 
Ttmica  adnata,  648. 

albuginea  testis,  449. 

conjunctiva,  648. 

erythroides,  448. 

propria  testis,  449. 

Ruyschiana,  657. 

sclerotica,  654. 

vaginalis  testis,  448. 

vasculosa  testis,  449  (note). 

Tunics  of  eye.     See  Eye. 
Turbinated  bone,  inferior,  56. 

-  middle,  41, 

superior,  or  ethmoidal,  41. 

'  sphenoidal,  38. 


Ti/mpanic  bone,  circle,  or  ring,  45 
T)/mpanum,  bones  in,  674. 

circumference  of,  672. 

lining  membrane  of,  670. 

membrane  of,  675. 

secondary,  671. 


•  orifice  of,  cochlear,  671. 
vestibular,  670. 


—  recess  of,  672. 

—  wall  of,  external,  669. 
internal,  670. 


Ulna,  79. 

and  tibia,  upper  parts  of,  compared,  107, 

Vmbilicus,  308. 


Unciform  bone,  83. 

eminence,  730. 


Unguis,  730. 
Urachus,  443. 
Ureter,  440. 

structure  of,  441. 

orifices  of,  444. 

muscles  of,  445. 

valve  of,  444. 

Urethra,  female,  469, 

muscles  of,  470, 


male,  457. 

bulb  of,  459. 

dilatations,  or  sinuses,  459. 

internal  surface,  459. 

lacunee,  460. 

membranous  portion,  459. 

muscles  of,  457. 

prostatic  portion  of,  457. 

spongy  portion  of,  459. 

structure  of,  460. 


Urinary  apparatus,  435, 

Uterine  veins,  467. 

Uterus,  464. 

cavity  and  mouth  of,  465, 
cervix  or  neck  of,  465, 
coat,  mucous,  467, 
-  serous,  467, 


•  development,  468. 

■  follicles  of,  466. 

•  functions  of,  468. 

■  fundus  of,  466. 

•  glands,  tubular,  of,  468  (note). 

■  gravid,  fibres  of,  467. 
sinuses  of,  467. 

-  vessels  and  nerves  of,  464. 


■  ligaments  of,  broad,  466. 
round,  466. 

•  nerves  of,  468. 

•  structure  of,  466. 
vessels  of,  468. 


Utriculus  vestibuli,  681. 
Uvea,  670. 
Uvula,  332. 

vesicae,  459. 

cerebelli,  715  (note). 

Vagina,  468. 

bulb  of,  469. 


—  columns  and  rugse  of,  468. 

—  development  of,  469. 

—  mucous  membrane  of,  469. 

—  muscles  of,  469. 
structure  of,  468. 


Vaginal  process  of  temporal  bone,  44. 
Valve  of  Bauhin,  372. 

•  Eustachian,  486. 

•  ileo-ccecal,  372. 
colic,  372, 

■  mitral,  484, 

■  pyloric,  352, 

■  of  Thebesius,  486. 

■  tricuspid,  484. 

■  of  Vieussens,  711. 
'  columella  of,  71S. 


Valves  of  Kerkringius,  365. 

of  heart.     See  Heart. 

of  intestines.     See  Intestine 

of  lymphatics,  617. 

semilunar,  or  sigmoid,  464. 

of  Tarin,  720. 

of  veins,  575. 
Valvula  conniventes,  365. 
Vas  aberrans,  452. 
deferens,  452. 

structure,  452. 


Vasa  afferentia,  lymphatic,  614. 
brevia,  arterial,  509. 
venous,  599. 


■  efferentia  of  epididymis,  451. 
•  lymphatic,  614, 


'  sudatoria,  634. 
•  vasorum  of  arteries,  520, 
of  veins,  576, 


—  vorticosa,  587.  665. 
Veins,  in  general,  573, 

—  anastomoses  of,  574, 
branches  of,  575. 

—  coats  of,  576. 

—  course  of,  574. 


INDEX. 


905 


Veins,  deep,  574. 

method  of  description  of,  577. 

nerves  of,  576. 

^^—  origin  of,  574. 

plexuses  of,  574. 

preparation  of,  576. 

relations  of,  with  arteriei,  575. 

satellite,  574. 

sinuses  of,  575. 

structure  of,  576. 

sub-cutaneous,  574. 

superficial,  574. 

termination  of,  575. 

valves  of,  575. 

varieties  of,  575. 

vasa  vasorum  of,  575. 

vessels  of,  575. 

in  particular,  577. 

abdominal  sub-cutaneoiu,  604. 

of  ala  of  nose,  588. 

alveolar,  589. 

angular,  588. 

of  the  arm,  superficial,  594. 

articular,  of  knee,  603. 

ascending  cervical,  580. 

lumbar,  606. 

auricular  anterior,  590. 

posterior,  590. 

axillary,  593. 

azygos,  general  remarks  on,  60) 

great,  605. 

lesser,  606. 

lumbar,  607. 


■  basilic,  595. 

■  brachial,  597. 

•  brachio-cephalic,  left  and  right,  *;  * 

■  bronchial,  left,  420. 
right,  420,  606. 

-  distribution  of,  421. 


'  buccal,  589. 

■  calcaneal,  internal,  604. 

■  capsular,  inferior  and  middle,  591 

■  cardiac,  great,  578. 
small,  578. 


cava,  ascending  or  inferior,  596. 

descending  or  superior,  51H 

cephalic,  595. 

■  of  thumb,  594. 


•  cerebral,  inferior,  anterior,  587. 

lateral,  584. 

'  median,  586. 


internal,  585. 
superior,  585. 

■  median,  SSC 


■  cerebellar,  anterior  lateral,  58* 
inferior  lateral,  5Sa 


'  cervical,  ascending,  580. 
deep,  580. 


■  choroid,  586. 

of  eye,  658. 

•  ciliary,  587. 

'  circumflex,  brachial,  598. 

femoral,  603. 

•  iliac,  603. 


'  colic,  left  and  right,  599. 

■  coronary  of  the  heart,  anterior,  578. 

great,  578. 

lips,  inferior,  589. 

—  superior,  589. 


stomach,  362. 

•  of  the  corpus  cavemosum,  601. 
striatum.  586. 


deep  cervical,  580. 

—  femoral,  603. 


•  dental,  anterior,  589 

inferior,  590. 

superior,  589 

■  diaphragmatic,  601. 

'  diploic,  585,  591. 

•  dorsal  of  the  foot,  deep,  602. 
external,  603. 

internal,  603. 


'  nose,  588. 
-  penis,  601. 


'  dorsi-spinal,  608. 

■  of  the  dura  mater,  583. 

■  at  the  elbow,  595. 
•  emulgent,  598. 

■  epigastric,  deep,  603. 
superficial,  60S 


Veins,  facial,  588. 

posterior,  589, 


of  the  falx  cerebri,  586. 

•  femoral,  603. 
deep,  603. 

•  frontal,  587. 

■  of  Galen  in  brain,  584. 
■  heart,  577. 


•  gastro-epiploic,  361. 
■  gluteal,  601. 

•  of  hand,  superficial,  594. 

•  hemorrhoidal,  inferior,  601. 
'  middle,  601. 

--superior,  601. 


—  head,  general  remarks  on,  592. 

—  hepatic,  600. 

in  the  liver,  391,  398. 

—  hypo-gastric,  601. 

—  iliac,  common,  600. 

eriemal,  603. 

internal,  601. 

—  ilio-lumbar,  607. 

—  infra-orbital,  589. 

—  innominate  of  Meckel,  579. 
■  of  Vieussens,  578. 


■  inter-costal,  607. 

superior,  left,  606. 

right,  606. 


lobular,  of  liver,  391  (note). 


—  of  intestines,  599. 

—  intra-lobular,  of  liver,  393  (note). 

spinal,  609. 

anterior,  longitudinal,  609. 

■  transverse,  609. 


-  lateral,  610. 

—  posterior,  longitudinal,  610. 
•  transverse,  610. 


■jugular,  581. 

anterior,  582. 

external,  581. 


compared  with  cranial,  610. 


—  internal,  or  deep,  583. 
posterior,  607. 


•  laryngeal,  inferior,  580. 
—  superior,  582. 


'  lingual,  590. 

'  longitudinal  of  scull,  inferior,  586. 

spine.     See  Intraspinal. 

■  of  lower  extremity,  deep,  602. 

superficial,  603. 


lumbar,  or  vertebro-lumbar,  5'17. 

ascending,  606. 

azygos,  607. 


'  mammary,  internal,  580. 
masseteric,  anterior,  589. 
•  posterior,  590. 


'  mastoid,  584,  590. 
■  maxillary,  external,  588. 
'  intornal,  589. 


—  median  of  the  fom,  595. 

basilic,  595. 

cephalic,  595. 

—  mediastinal,  580,  60C. 

—  medullary,  610. 

—  meningeal,  591. 
■  middle,  590. 


■  mesaraic,  599. 
'  mesenteric,  inferior  or  smaL,  &(*^ 
superior  or  gre.  t,  59^ 


'  nasal,  588. 

•  obturator,  601. 

■  occipital,  deep,  590. 

superficial,  589. 


■  (esophageal,  606. 

■  omphalo-mesenteric,  599. 

■  ophthalmic,  587. 

■  orbital,  external,  589. 

■  ovarian,  598. 

•  palatine,  inferior,  589. 
su-perior,  589. 


palmar,  593. 
'  palpebral,  external,  589. 
'  inferior,  588. 


•  pancreatic,  402. 

•  parotid,  590. 

•  of  particular  organs  or  tissues. 

gans  or  tissues. 

•  of  pelvis,  in  female,  602. 
male,  601. 


of  penis,  601. 

5Y 


906 


INDEX. 


Veins,  pericardiac,  580. 

peroneal,  602. 

pharyngeal,  591. 

phrenic,  inferior,  598. 

. superior,  580. 

plantar,  602. 

popliteal,  602. 

portal,  or  vena  porta,  597,  599. 

branches  of  origin  of,  598. 

in  the  liver,  390. 

■  sinus  of,  599. 


profunda  cervicis,  580. 
femoris,  603. 


—  pterygoid,  590. 

—  pudic,  external,  604. 
internal,  601. 

—  pulmonary,  577. 
'  distribution  of,  421. 


■  rachidian.    See  Spinal. 

■  radial  cutaneous,  595. 
deep,  594. 

•  ranine,  590. 

■  renal,  597. 

'  sacral,  lateral,  607. 
middle,  607. 


'  salvatella,  594. 
'  of  Santorini,  585. 
'  saphenous,  external,  605. 
'  internal,  603. 

'  second,  604. 


'  satellite,  of  lingual  nerve,  590. 
■  scapular,  superior,  582. 
posterior,  582. 


^—  sciatic,  601. 

scrotal,  601. 

semi-azygos,  606. 

short,  of  stomach,  599. 

spermatic,  left  and  right,  598. 

spheno-palatine,  589,  591. 

spinal,  605. 

'—  deep.     See  Intraspinal. 

general  remarks  on,  611. 

posterior,  deep.     See  Inira^spinal. 

■  superficial,  608. 


■  superficial,  60S. 

in  neck,  608. 

—  posterior,  608. 


■  of  spinal  cord,  610. 
•  splenic,  599. 

■  distribution  of,  406. 


■  stylo-mastoid,  590. 

sub-clavian,  left  and  right,  593. 
mental,  589. 

supra-orbital,  588. 

renal,  inferior  and  middle,  598 


scapular,  581. 

sural,  603. 

temporal,  589. 

deep,  590. 

middle,  589. 

•  superficial,  589. 


•  temporo-maxillary,  589. 
■ofThebesius,  578. 

•  thymic,  580. 

•  thyroid,  inferior,  580. 

middle,  591. 

superior,  591. 

•  tibial,  anterior,  602. 
-posterior,  602. 


tibio-peroneal,  602. 
tonsillar,  333. 
transverse,  cervical,  582. 

facial,  590. 

humeral,  582. 


■  ulnar  cutaneous,  anterior,  595. 
—  posterior,  595. 


■  deep,  592. 


•  umbilical,  600. 

■  of  upper  extremity,  deep,  592. 
superficial,  593. 

•  uterine,  467,  601,  602. 

■  vaginal,  602. 

•  vasa  brevia,  599. 
vorticosa,  587. 

■  ventricular,  cerebral,  586. 

■  of  vertebra,  610. 

■  vertebral,  581. 

•  vertebro-costal,  inferior,  606. 

superior,  left,  606. 

— i right,  605 


Veins,  vertebro-lumbar,  607. 

vesical,  female,  602. 

male,  601. 


vidian,  589. 

Velum  interpositum,  731,  740. 

meduUare,  anterior,  713. 

posterior,  718  (note). 


palati,  331.     See  Palate,  soft. 

pendulum  palati,  331. 

Vena  cava  inferior,  or  ascending,  596. 
superior,  or  descending,  578. 


Venm  comites,  572, 

minimse,  508. 

Venous  plexuses.    See  Plexuses. 

system  generally,  572. 

Venter  ilii,  or  internal  iliac  fossa,  88. 
Ventricle  of  Arautius,  704. 

of  corpus  callosum,  737. 

fifth,  738. 

fourth,  718. 

choroid  plexuses  of,  720. 


—  fibrous  layers  of,  719. 
--  fossette  of,  704. 

■  laminated  tubercle  of,  717 
•  orifice,  inferior,  719. 

■  semilunar  fold  of,  719. 
valves  of  base  of,  719. 


■  of  larynx,  424. 

■  lateral,  744. 

body  of,  744. 

comu  anterior,  744. 

descending,  744. 

posterior,  744. 


■  of  septum  lucidum,  738. 
•third,  729,  741. 

choroid  plexuses  of,  741. 

commissure  of,  anterior,  742. 

posterior,  742. 

-  soft  or  gray,  729,  741. 


■  floor  of,  anterior  part  of,  729. 

middle  and  posterior  part  of, 

729. 
•  openings  of,  742. 


Ventricles,  cerebral,  fluid  of,  744. 

lining  membrane  of,  747. 

Gall's  views  regarding,  750. 

— — of  heart.     See  Heart. 

of  spinal  cord,  701. 


Ventriculus,  352. 

succenturiatus,  362. 

Vermiform  appendix,  373. 

process,  inferior,  716. 

superior,  716, 


Vertebra,  cervical,  first,  23. 

second,  24. 

seventh,  25. 


dentata,  24. 

dorsal,  first,  25. 

eleventh  and  twelfth,  85. 

general  description  of,  19. 

lumbar,  fifth,  26. 

prominens,  25. 

Vertebra,  articular  processes  of,  in  different  regiou,  S8» 

articulations  of.     See  Articulatiom. 

bodies  of,  in  different  regions,  20. 

cervical,  19. 


• characters  of,  general,  19. 

distinctive,  20. 
proper,  22. 


—  coccygeal,  19. 

—  development  of,  31. 

—  dorsal,  19. 

—  false,  19. 

—  foramen  of,  in  different  regions,  19. 

—  internal  structure  of,  31. 

—  laminse  of,  in  different  regions,  20. 

—  ligaments  of.     See  Ligaments. 

—  lumbar,  19. 

—  notches  of,  in  different  regions,  80. 
--  number  of,  19, 

—  sacral,  19, 

-►  sacro-coccygeal,  26. 

union  of,  32. 


spinous  processes  of,  in  different  regions,  SS, 

transverse  processes  of,  in  diflferent  region*, 

23. 
■true,  19. 


Vertebral  canal,  30. 

column,  19. 

articulations  of,  115-123. 


INDEX. 


90*2 


Vertebral  column,  curvatuiea  of,  28. 

deTelopment  of,  32. 

'  dimensions  of,  28. 

figure  and  aspects  of,  29. 

'  moTements  of  entire,  121-123. 


grooves,  20. 
ligaments. 


See  Ligaments. 
See  Veins. 


Vertebro-costaX  veins. 
Yerumontanum,  461. 
Vesica  fellea,  394. 

urinaria,  440. 

Vesicles,  Graafian,  461. 
Vesicula  seminales,  453. 

efferent  duct  of,  454. 

structure,  454. 

Vestibule  of  ear,  676. 

aqueduct  of,  676. 

calcareous  matter  of,  681. 

crista  of,  676. 

■         fovea  and  recessus  sulcifonnis,  676. 

membranous,  680. 

openings  into,  676. 

sacculus  of,  680. 

— ; sinus,  common,  or  utricle  of,  680. 

Visceral  nerves.    See  iferves. 
Vitreous  table  of  cranial  bones,  35. 


Vocal  cords,  426. 
Vomer,  57. 
Vulva,  470. 

development  of,  471. 

fourchette,  470. 

mucous  membrane,  471. 

parts  of,  470. 


Wings  of  sphenoid  bone,  lesser,  37. 
great,  38. 


Ingrassius,  37 

Womb.  See  Uterus. 
Wormian  bones,  50. 
Wrist.    See  Carpus. 

Xiphoid  cartilage,  or  appendix,  65. 

Zinn,  zone  of,  655. 
Zonula  Zinni,  655. 
Zygoma,  61. 
Zygomatic  arch,  61. 

bone,  54. 

canal,  55. 


-  fossa,  61. 

-  process  of  temporal  bone,  42. 
malar  bone,  55. 


THE  END. 


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